JP2003029589A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately set a cleaning operation period by appropriately setting the finishing time of operation to remove toner adhering to the image carrier of an image forming device. SOLUTION: This image forming device is equipped with a cleaning work control means having a cleaning work performing means for performing cleaning work that the toner attracted and held on toner attracting and holding members CLp and CLt is reversely shifted to toner adhering rotating members PR, B and T2b and the toner on the surfaces of the members PR, B and T2b is shifted to the member B to which the toner is recovered by the cleaner CLb so as to recover the toner to the cleaner CLb, a cleaning work starting means for starting the cleaning work in set timing and a cleaning work finishing means for finishing the cleaning work according to a detected concentration signal from a toner concentration sensor SN1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary toner image carrier on which a toner image is formed on a rotating surface, an intermediate toner image carrier on which the toner image is intermediately transferred, and the intermediate toner image carrier. And an image forming apparatus provided with a sheet transfer device for transferring the toner image on the surface of the recording sheet to a recording sheet. The present invention relates to an image forming apparatus including a toner adsorption holding member that ejects the toner that is temporarily adsorbed and retained at the timing of, and a toner recovery cleaner that recovers the ejected toner. The present invention is
It can be applied to image forming apparatuses such as electrophotographic copying machines, laser beam printers, and electrostatic recording devices. Further, the present invention is particularly preferably applicable to an image forming apparatus having a plurality of primary toner image carriers.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, and a facsimile, when forming a color image, a plurality of primary toner image bearing members (Y ( Yellow), M (magenta), C (cyan), K (black primary toner image carrier)
And the toner images of the respective colors formed on the plurality of primary toner image bearing members are transferred onto the intermediate toner image bearing member (intermediate transfer belt, intermediate transfer drum, or other intermediate transfer member) in an overlapping manner. An image forming apparatus of the type that transfers a toner image on the surface of an image carrier to a recording sheet has been conventionally known. When a plurality of such primary toner image bearing members (photoconductors) are used, a plurality of respective primary toner image bearing members (photoconductors) and the intermediate toner image bearing members (intermediate transfer belt or intermediate transfer drum, etc.) are used. If a cleaner that cleans the residual toner on the surface of each of the intermediate transfer members) is provided, the number of cleaners increases, which makes it difficult to downsize the image forming apparatus and reduce the manufacturing cost. It was

The following techniques (J01) and (J02) are conventionally known as methods for solving the above-mentioned problems. (J01) Japanese Patent Application Laid-Open No. 11-249452 In this publication, a toner holding means for temporarily adsorbing and holding the residual toner remaining on the image carrier after the transfer is provided, and the adsorbing means holds the toner from the toner holding means at a predetermined timing. A technique is disclosed in which the held toner is discharged and collected by a cleaner provided on an intermediate toner image carrier (intermediate transfer member). (J02) Japanese Patent Application Laid-Open No. 11-311894 In this publication, the toner adhering to the brush is returned to the photoconductor at the end of a series of jobs (image forming operation) and when a certain number of images are recorded. There is described a cleanerless technique in which the cleaning operation is performed by recovering the toner returned to the developing device.

[0004]

(Problems of the prior art) In the above prior art, since there is no criterion for determining the end time of the discharged toner collection, if the cleaning operation takes a sufficient time, the productivity of image recording decreases. If the time is not taken, the cleaning may be insufficient and the image quality may be deteriorated. The present invention has been made in view of the above circumstances (and the examination results).
Primary toner image carrier (photoconductor) and intermediate toner image carrier (intermediate transfer belt, intermediate transfer drum, or other intermediate transfer member)
A cleaner is provided on one of the toner image bearing members including
An image forming apparatus that temporarily attracts and holds the toner to another toner image carrier, and that is provided with a toner attracting and holding member that ejects the attracted and held toner at a predetermined timing, and collects the ejected toner in the cleaner. In the above, the subject is the contents described in (O01) below. (O01) To properly determine the cleaning operation period by appropriately determining the end time of the cleaning operation.

[0005]

The present invention devised to solve the above problems will now be described. The elements of the present invention are to facilitate correspondence with the elements of the embodiments described later. Note that the reference numerals of the elements of the embodiments are enclosed in parentheses. The reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention and not to limit the scope of the present invention to the embodiments. (Invention) In order to solve the above problems, an image forming apparatus of the present invention is characterized by having the following constituent requirements (A01) to (A010). (A01) A primary toner image carrier (PR, Py, ...) having a toner image formed on its surface and carrying the formed toner image.
Pk) and the primary toner image carrier (PR, Py to Pk)
A plurality of toner image carriers (P, B1 to B3) to which the toner image on the surface of the toner image is transferred.
R, B; Py to Pk, B; Py to Pk, B1 to B3),
(A02) A sheet transfer device (T) for transferring the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S).
2), (A03) a cleaner (CLb, CL3) disposed adjacent to the surface of the intermediate toner image carrier (B, B3) for collecting the toner adhering to the surface into a toner recovery container,
(A04) The primary toner image carrier (PR, Py to Pk)
A toner adsorbing / holding member (CL) that is disposed adjacent to the surface of the
p, CLy to CLk), (A05) Each toner image carrier (PR, B; Py to Pk, B; Py to Pk, B1, B)
2) transfer bias control means (C1) for applying a transfer bias for transferring the toner between (A06), the toner on the surface of the primary toner image carrier (PR, Py to Pk), and the toner adsorption holding member (CLp). , CLy to CLk), and an adsorption bias applying means (C3A) for applying an adsorption transfer bias for transferring to the toner adsorption holding member (CL).
p, CLy to CLk), the toner adsorbed and held by
Reverse transfer bias applying means (C) for applying a reverse transfer bias for reverse transfer to the next toner image carrier (PR, Py to Pk)
3B), toner adsorption transfer control means (C3), (A
07) Cleaner bias control means (C) for applying a cleaning bias for collecting the toner on the surface of the intermediate toner image carrier (B, B3) to the cleaner (CLb, CL3).
4), (A08) Sheet transfer device bias control means for applying a sheet transfer bias for transferring the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S) to the sheet transfer device (T2). (C2), (A09) The toner image carrier (PR, Py) that carries the toner image transferred to the recording sheet (S) by the sheet transfer device (T2).
To Pk, B, B1 to B3), a toner density sensor (SN1) for detecting the toner density on the surface of the toner, and (A010) the toner attracted and held by the toner attracting / holding member (CLp, CLy to CLk). The reverse transfer bias applying means (C3B) of the control means (C3) reversely transfers to the primary toner image carrier (PR, Py to Pk) and the surface of the primary toner image carrier (PR, Py to Pk). The toner on the surface of the intermediate toner image carrier (B, B1 to B3) is moved to the cleaner bias by the transfer bias control means (C1). Cleaning work execution means (C6B) for executing the cleaning work to be collected by the cleaner (CLb, CL3) by the control means (C4), and at the set timing. Serial and cleaning operation starting means for starting the cleaning operation (C6A), the toner concentration sensor (SN1) of the detected concentration signal cleaning work end means for ending the cleaning operation in accordance with (C6
Cleaning work control means (C6) having C).

(Operation of the Present Invention) In the image forming apparatus of the present invention having the above construction, the toner adsorption / transfer control means (C3)
Is the primary toner image carrier (PR, Py) by the transfer bias for adsorption applied by the adsorption bias applying means (C3A).
To Pk) toner on the surface of the toner adsorption holding member (CL
p, CLy to CLk) and the toner transfer holding members (CLp, CLy to CL) by the reverse transfer bias applied by the reverse transfer bias applying means (C3B).
The toner that is temporarily adsorbed and held by k) is reversely transferred to the primary toner image carrier (PR, Py to Pk). The transfer bias control means (C1) is provided for each toner image carrier (P
A transfer bias is applied between R, B; Py to Pk, B; Py to Pk, B1 to B3) to transfer the toner. The cleaner bias control means (C4) applies the cleaning bias to the intermediate toner image carrier (B, B1 to B1).
B3) The toner adhered to the surface is cleaned by the cleaner (CLb,
CL3) collects the toner in a toner collecting container. The sheet transfer device bias control means (C2) applies a sheet transfer bias to the sheet transfer device (T2) to record the toner image on the intermediate toner image carrier (B, B1 to B3) on the recording sheet (S). Transfer to. The toner concentration sensor (SN1) uses the sheet transfer device (T2) to transfer the recording sheet (S).
The toner density on the surface of the toner image carrier (PR, Py to Pk, B, B1 to B3) carrying the toner image transferred to is detected. The cleaning work starting means (C6A) of the cleaning work control means (C6) starts the cleaning work at the set timing. The cleaning operation executing means (C6B) uses the reverse transfer bias applying means (C3B) of the toner adsorption / transfer control means (C3) to set the toner adsorbed and held by the toner adsorption / holding members (CLp, CLy to CLk) to 1 The toner on the surface of the primary toner image carrier (PR, Py to Pk) is reversely transferred to the next toner image carrier (PR, Py to Pk) and is transferred to the intermediate toner image carrier (C1) by the transfer bias control means (C1). B, B1 to B3) to move the toner on the surface of the intermediate toner image carrier (B, B1 to B3) to the cleaner (CL) by the cleaner bias control means (C4).
b, CL3). The cleaning operation ending means (C6C) ends the cleaning operation according to the detected density signal of the toner density sensor (SN1). Therefore, it is possible to prevent the cleaning work from being performed for an unnecessarily long time in a state where the detected density of the toner density sensor (SN1) is lowered, and to prevent the deterioration of the image forming work efficiency.

The present invention having the above-mentioned constituents (A01) to (A010) can be provided with the following constituents (A011) to (A014). (A011) The intermediate toner image carrier (B, B1 to B3)
The sheet transfer device (T2) having a sheet transfer roll (T2b) for transferring the toner image on the recording sheet (S),
(A012) A toner adsorbing / holding member (CLt) for a transfer roll, which is disposed adjacent to the surface of the sheet transfer roll (T2b) and temporarily adsorbs and holds the toner adhering to the surface of the sheet transfer roll (T2b), (A013) Adsorption bias applying means (C5A) for applying an adsorption transfer bias for transferring the toner on the surface of the sheet transfer roll (T2b) to the toner adsorption holding member (CLt), and the toner adsorption holding member (CLt). Reverse transfer bias applying means (C5) for applying a reverse transfer bias for reversely transferring the toner adsorbed and held on the sheet transfer roll (T2b).
Toner adsorption transfer control means (C) for a transfer roll having B)
5), (A014) The toner that is attracted and held by the toner attracting and holding member (CLt) by the reverse transfer bias applying means (C5B) of the transfer roll toner adsorption and transfer control means (C5) is the sheet transfer roll (T2b). The toner on the surface of the sheet transfer roll (T2b) to the intermediate toner image carrier (B, B1 to B3) by the sheet transfer device bias control means (C2), and the cleaner bias control means. The cleaning work executing means (C6) for executing the cleaning work for collecting the toner on the surface of the intermediate toner image carrier (B, B1 to B3) by the cleaner (CLb, CL3) by (C4).
B).

In the present invention having the above structural requirements (A011) to (A014), the sheet transfer device (T2) is constituted by a sheet transfer roll (T2b), and the surface of the sheet transfer roll (T2b). The toner adsorbing / holding member (CLt) for the transfer roll, which is arranged adjacent to, temporarily adsorbs and holds the toner adhering to the surface of the sheet transfer roll (T2b). The attraction bias applying means (C5A) of the transfer roll toner attraction transfer control means (C5) applies the attraction transfer bias to the sheet transfer roll (T2).
The toner on the surface of (b) is transferred to the toner adsorption holding member (C5).
A) and reverse transfer bias applying means (C5
B) applies a reverse transfer bias to reversely transfer the toner attracted and held by the toner suction holding member (CLt) to the sheet transfer roll (T2b). The cleaning operation executing means (C6B) is a reverse transfer bias applying means (C5) of the transfer roll toner adsorption transfer control means (C5).
The toner attracted and held by the toner suction holding member by B) is reversely transferred to the sheet transfer roll (T2b),
The sheet transfer device bias control means (C2) moves the toner on the surface of the sheet transfer roll (T2b) to the intermediate toner image carrier (B, B1 to B3), and the cleaner bias control means (C4). The toner on the surface of the intermediate toner image carrier (B, B1 to B3) is collected by the cleaner (CLb, CL3).

The present invention having the above-mentioned constituents (A01) to (A010) can be provided with the following constituents (A015) and (A016). (A015) A plurality of the primary toner image carriers (PR, Py to Pk) on which toner images of different colors are formed, (A016)
A plurality of primary intermediate toner image carriers (B, B1) to which toner images are transferred from the plurality of primary toner image carriers (Py to Pk).
To B3), the primary intermediate toner image carrier (B, B1) in which the toner adsorption holding member is arranged adjacent to the surface.
To B3) and the plurality of primary intermediate toner image bearing members (B
The toner image on the surface of (1, B2) is secondarily transferred.
The second intermediate toner image carrier (B3), wherein the cleaners (CLb, CL3) are arranged adjacent to the surface.
The intermediate toner image carrier (B1), and the intermediate toner image carrier (B3),

In the present invention having the above-mentioned structural requirements (A015) and (A016), a plurality of the primary toner image bearing members (Py to
Toner images of different colors are formed on Pk). Intermediate toner image carrier (B1 to B3) primary intermediate toner image carrier (B
1, B2) are the plurality of primary toner image carriers (Py to
The toner image is transferred from Pk). The toner adhering to the surface of the primary intermediate toner image carrier (B1, B2) is adsorbed and held by the toner adsorbing and holding members (CL1, CL2) arranged adjacent to the surface thereof. A secondary intermediate toner image carrier (B3) to which the toner images on the surfaces of the plurality of primary intermediate toner image carriers (B1, B2) are secondarily transferred.
Is a cleaner (CL3) placed adjacent to its surface
Thus, the toner adsorbed on the surface is collected.

The image forming apparatus of the present invention has the following constituent elements (A01), (A02 ') to (A04'), (A05), (A).
06 ')-(A010'). (A01) A primary toner image carrier (PR, Py, ...) having a toner image formed on its surface and carrying the formed toner image.
Pk) and the primary toner image carrier (PR, Py to Pk)
A plurality of toner image carriers (P, B1, B2) to which the toner image on the surface of the toner image is transferred.
R, B; Py to Pk, B; Py to Pk, B1 to B3),
(A02 ') a sheet transfer roll (T2b) for transferring the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S), (A03') the sheet transfer roll (T2)
A cleaner (CLb, CL) disposed adjacent to the surface of b) for collecting the toner adhering to the surface into a toner recovery container
3), (A04 ′) The plurality of toner image bearing members (PR,
B; Py to Pk, B; Py to Pk, B1 to B3), which are arranged adjacent to the surface of the toner image carrier and temporarily adsorb and retain the toner adhering to the surface of the toner image carrier (CLp, CLy to CLk, CL1, CL2), (A0
5) Each of the toner image bearing members (PR, B; Py to Pk,
B; transfer bias control means (C) for applying a transfer bias for transferring toner between Py to Pk and B1 to B3)
1), (A06 ') Each of the plurality of toner image carriers (PR,
B; Py to Pk, B; Py to Pk, B1 to B3), the toner on the surface of the toner adsorption holding member (CLp, CLy to
CLk, CL1, CL2) and a biasing means for applying attraction (C3A) for applying a transfer bias for attraction for transferring to CLk, CL1, CL2, and the toner suction holding members (CLp, CLy to CLk,
The toners adsorbed and held by CL1 and CL2 are respectively attached to the toner image carriers (PR, B; Py to Pk, B; Py to Pk,
B1 to B3) has a reverse transfer bias applying means (C3B) for applying a reverse transfer bias for reverse transfer to toner adsorption transfer control means (C3), (A07 '), and the toner on the surface of the sheet transfer roll (T2b) is cleaned by the cleaner. (CLb, C
Cleaner bias control means (C4) for applying a cleaning bias for collection to L3), (A08 ') a sheet transfer bias for transferring the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S). Sheet transfer device bias control means (C2) for applying to the sheet transfer roll (T2b), (A09 ') The sheet transfer roll (T2)
b) A toner concentration sensor (S which detects the toner concentration on the surface)
N1), (A010 ′) the toner suction holding member (CL
(p, CLy to CLk, CL1, CL2), the toner image carrier (PR, B; Py to Pk) is held by the reverse transfer bias application means (C3B) of the toner adsorption transfer control means (C3). , B; Py to Pk, B1
To B3), the toner image bearing members (PR,
B; Py to Pk, B; Py to Pk, B1 to B3) surface toner is moved by the transfer bias control means (C1), and the toner on the surface of the intermediate toner image carrier (B, B3) is transferred to the sheet transfer device. Bias control means (C2) moves to the sheet transfer roll (T2b), and the cleaner bias control means (C4) executes a cleaning operation for collecting toner on the surface of the sheet transfer roll (T2b) to the cleaner (CLt). Cleaning work executing means (C6B) and cleaning work starting means (C6) for starting the cleaning work at a set timing.
Cleaning work control means (C6) having A) and cleaning work end means (C6C) for ending the cleaning work in response to the detected density signal of the toner density sensor (SN1).

The above structural requirements (A01), (A02 '), (A
In the image forming apparatus of the present invention including 04 '), (A05), (A06') to (A010 '), the toner attracting and transferring control means (C3) is attracted by the attracting bias applying means (C3A). A plurality of toner image carriers (PR, B; Py to Pk, B; Py to Pk, B1 to B) depending on the transfer bias for use.
3) The toner on the surface of the toner adsorption holding member (CL
p, CLy to CLk, CL1, CL2) and the toner transfer holding member (CL) by the reverse transfer bias applied by the reverse transfer bias applying means (C3B).
The toner temporarily adsorbed and held on p, CLy to CLk, CL1, CL2) is the toner image carrier (PR, B;
Py to Pk, B; Py to Pk, B1 to B3). The transfer bias control means (C1) includes the toner image carriers (PR, B; Py to Pk, B; Py to Pk, B).
1 to B3), a toner image transfer bias is applied to transfer the toner. The cleaner bias control means (C4) is
By applying a cleaning bias, the toner on the surface of the sheet transfer roll (T2b) is removed from the cleaner (C).
Lt). Sheet transfer device bias control means (C
2) applies a sheet transfer bias to the sheet transfer roll (T2b) to apply the intermediate toner image carrier (B,
The toner image on B3) is transferred to the recording sheet (S). The toner concentration sensor (SN1) detects the toner concentration on the surface of the sheet transfer roll (T2b).

The cleaning work starting means (C6A) of the cleaning work control means (C6) starts the cleaning work at the set timing. The cleaning work execution means (C6B) performs the following work. (1) The toner suction holding member (CLp, CLy to CL)
The toners adsorbed and held on the toner image carrier (PR, CL, CL2) are applied to the toner image carrier (PR,
B; Py to Pk, B; Py to Pk, B1 to B3). (2) Each of the toner image carriers (PR, B; Py to Pk,
B; Py to Pk, B1 to B3) surface toner is moved by the transfer bias control means (C1), and the toner on the surface of the intermediate toner image carrier (B, B3) is moved to the sheet transfer device bias control means (C2). Is moved to the sheet transfer roll (T2b). (3) The cleaner bias control means (C4) causes the cleaner (CLt) to collect the toner on the surface of the sheet transfer roll (T2b). The cleaning work ending means (C6C) of the cleaning work control means (C6) is provided with the toner concentration sensor (SN).
The cleaning operation is completed in response to the detected concentration signal of 1).

The image forming apparatus of the present invention has the following constituent elements (A01 '), (A02), (A03 "), (A04"),
(A05), (A06 ″), (A07 ″), (A08), (A0
9) and (A010 ″) are provided. (A01 ′) A plurality of primary toner image carriers (P1) having a toner image formed on the surface thereof and carrying the formed toner image.
R, Py to Pk) and the primary toner image carrier (PR, Pk)
y to Pk) and a plurality of toner image carriers (PR, B; Py to Pk, B; Py to Pk, B1) including an intermediate toner image carrier (B, B1 to B3) to which the toner image on the surface is transferred. ~ B
3), (A02) a sheet transfer device (T2) for transferring the toner image on the intermediate toner image carrier (B, B3) to a recording sheet (S), (A03 ″) the plurality of toner image carriers (P2)
R, B; Py to Pk, B; Py to Pk, B1 to B3), and a cleaner (CLb, CL3) is disposed adjacent to the surface of the toner image carrier and adheres to the surface. The toners carried by the cleaner (CLb, CL3) are collected in the toner collecting container by the cleaners (B, B3), (A04 ″) The toner images other than the cleaner-carrying toner image carrier (B, B3) Carrier (PR, P
y to Pk, B1, B2) for temporarily adsorbing and holding the toner adhering to the surface thereof (CL)
p, CLy to CLk, CL1, CL2) are arranged adjacent to the surface of the toner image carrier (PR, Py) with a holding member.
To Pk, B1, B2), (A05) each of the toner image carriers (PR, B; Py to Pk, B; Py to Pk, B1 to B)
3) Transfer bias control means (C1) for applying a transfer bias for transferring toner between them, (A06 ″) the toner image carrier (PR, Py to Pk, B1, B2) with the holding member.
The toner on the surface of the toner adsorption holding member (CLp, C
Adsorption bias applying means (C3) for applying an adsorption transfer bias for transferring to Ly to CLk, CL1, CL2)
A) and the toner adsorption / holding member (CLp, CLy to
The toners adsorbed and held on CLk, CL1, CL2) are held by the toner image carrier (PR, Py to Pk, B) with the holding member.
1, B2) has a reverse transfer bias applying means (C3B) for applying a reverse transfer bias for reverse transfer, and toner adsorption transfer control means (C3), (A07 ″) surface of the toner image carrier with cleaner (B, B3) Cleaner bias control means (C4), (A08) for applying a cleaning bias for collecting the toner of No. 2 to the cleaners (CLb, CL3)
Sheet transfer device bias control means (C2) for applying a sheet transfer bias for transferring the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S) to the sheet transfer device (T2), (A09). ) The toner image carrier (PR, Py to Pk, B, B) carrying the toner image transferred to the recording sheet (S) by the sheet transfer device (T2).
1 to B3), a toner concentration sensor (SN1) for detecting the toner concentration on the surface, (A010 ″) the toner attracted and held by the toner attracting and holding members (CLp, CLy to CLk, CL1, CL2) to the toner attracting transfer. Control means (C3)
By the reverse transfer bias applying means (C3B), the toner image carrier (PR, Py to Pk, B1,
B2) and the toner on the surface of the toner image bearing member (PR, Py to Pk, B1, B2) with the holding member is cleaned by the transfer bias control means (C1) with the toner image bearing member (B, B3) with a cleaner. To a cleaning operation executing means (a cleaning operation executing means for causing the cleaner bias control means (C4) to collect the toner on the surface of the cleaner-attached toner image carrier (B, B3) to the cleaner (CLb, CL3). C6B), a cleaning work starting means (C6A) for starting the cleaning work at a set timing, and a cleaning work ending means (C6C) for ending the cleaning work according to the detected density signal of the toner density sensor (SN1). )
Cleaning work control means (C6) having and.

The above constituent elements (A01 '), (A02), (A
03 ″), (A04 ″), (A05), (A06 ″), (A0
7 ″), (A08), (A09), and (A010 ″), the image forming apparatus of the present invention includes a plurality of toner image carriers (PR,
B; Py to Pk, B; Py to Pk, B1 to B3), and a toner image carrier with a cleaner in which a cleaner (CLb, CL3) is disposed adjacent to the surface thereof. (B, B3) is the cleaner (CLb, CL) to which the toner attached to the surface is applied with a cleaning bias by the cleaner bias control means (C4).
By 3), the toner is collected in the toner collecting container. A toner image carrier (PR, Py to Pk, B1, B2) other than the toner image carrier with cleaner (B, B3) and a toner adsorption holding member (CLp, CLy to CLk, CL1, CL).
In the toner image carrier (PR, Py to Pk, B1, B2) with the holding member 2) arranged adjacent to the surface, the toner adhering to the surface of the toner image carrier (CLp, CLp,
CLy to CLk, CL1, CL2) are temporarily adsorbed and held.

The attracting bias applying means (C3A) of the toner attracting and transferring control means (C3) applies the attracting transferring bias to the toner image carrier (PR, Py.
The reverse transfer bias applying means (C3B) for transferring the toner on the surface of Pk, B1, B2) to the toner adsorption holding members (CLp, CLy to CLk, CL1, CL2) is the toner adsorption holding members (CLp, CLy). CLk, CL
1, CL2) is reversely transferred to the toner image carrier (PR, Py to Pk, B1, B2) with the holding member. The transfer bias control means (C1) includes the toner image carriers (PR, B; Py to Pk, B; Py to P).
An image transfer bias is applied between k and B1 to B3) to transfer the toner. The sheet transfer device (T2) transfers the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S).

Sheet transfer device bias control means (C2)
Applies a sheet transfer bias to the sheet transfer device (T2) to transfer the toner image on the intermediate toner image carrier (B, B3) to the recording sheet (S). The toner concentration sensor (SN1) is the toner image carrier (PR, Py to Pk, B, B1 to B3) that carries the toner image transferred to the recording sheet (S) by the sheet transfer device (T2).
The toner density on the surface of is detected. Cleaning work starting means (C6A) of the cleaning work control means (C6)
Starts the cleaning work at the set timing.

The cleaning work executing means (C6B) is
Do the following: (1) The toner suction holding member (CLp, CLy to CL)
k, CL1, CL2), the toner adsorbed and held on the toner image carrier (PR, Py to Pk, B1, Reverse transfer to B2). (2) Each toner image carrier (PR; Py to Pk; Py)
The toner on the surfaces (Pk, B1, B2) is moved to the cleaner-attached toner image carrier (B, B3) by the transfer bias control means (C1). (3) The cleaner bias control means (C4) causes the cleaner (CLt) to collect the toner on the surface of the toner image bearing member (B, B3) with the cleaner. The cleaning work ending means (C6C) of the cleaning work control means (C6) is provided with the toner concentration sensor (SN).
The cleaning operation is completed in response to the detected concentration signal of 1).

Further, the image forming apparatus of the present invention is characterized by having the following constituent elements (B01) to (B06). (B01) A plurality of toner-adhering rotating members (PR, B, T2b; Py-) which rotate in contact with each other and adhere a toner image to the surface.
Pk, B, T2b; Py to Pk, B1 to B3, T2
b), (B02) the plurality of toner adhering rotary members (PR,
B, T2b; Py to Pk, B, T2b; Py to Pk, B
1 to B3, T2b), the toner adhering rotary members (PR, B, T2b; Py to Pk, B, T) that rotate in contact with each other.
2b; Py to Pk, B1 to B3, T2b), a toner transfer bias applying member for transferring toner, (B03) the plurality of toner adhering rotation members (PR, B, T2b; Py to
Pk, B, T2b; Py to Pk, B1 to B3, T2b)
A cleaner (CLb, CLt) for collecting the toner adhering to any one or more of the toner adhering rotary members, (B04) other than the toner adhering rotary member (B, T2b) for collecting the toner by the cleaner (CLb; CLt). Toner adhering rotary member (PR, T2b; Py to Pk, T2b; Py to
Pk, B1, B2, T2b) toner adsorption holding members (CLp, CLt;
CLy to CLk, CLt; CLy to CLk, CL1, C
L2, CLt; CLy to CLk, CL1 to CL3),
(B05) The plurality of toner adhering rotary members (PR, B, T
2b; Py to Pk, B, T2b; Py to Pk, B1 to B
3, T2b), a toner concentration sensor (SN1) for detecting the concentration of the toner adhering to the surface of the toner adhering rotary member, (B06), the toner adsorption holding member (CLp, CLt; CLy to CLk). , CLt; CLy ~
CLk, CL1, CL2, CLt; CLy to CLk, C
The toner adsorbed and held on L1 to CL3 is a toner adhering rotary member (PR, B, T2b; Py to Pk, B, T2b;
Py to Pk, B1 to B3, T2b) and the toner adhering rotary member (PR, B, T2b; Py to P)
k, B, T2b; Py to Pk, B1 to B3, T2b) The toner adhering rotary member (B; B3; T2) whose toner is collected by the cleaner (CLb, CLt).
b), the cleaner (CLb, CL3, C
Lt) cleaning work execution means (C6B) for executing cleaning work for collecting toner, cleaning work start means (C6A) for starting the cleaning work at a set timing, and detection of the toner concentration sensor (SN1) Cleaning work control means (C6) having a cleaning work ending means (C6C) for ending the cleaning work in accordance with a density signal.

In the image forming apparatus of the present invention having the above structural requirements (B01) to (B06), a plurality of toner adhering rotating members (PR,
B, T2b; Py to Pk, B, T2b; Py to Pk, B
1 to B3, T2b), the toner attached to the surface of any one or more toner adhering rotary members is directly collected by the cleaner (CLb, CLt). A toner adhering rotary member (PR, T2b; Py to Pk, other than the toner adhering rotary member whose toner is directly collected by the cleaner).
In T2b; Py to Pk, B1 to B3), the toner adhering to the surface of the toner is held by the toner adsorption holding members (CLp, CL).
t; CLy to CLk, CLt; CLy to CLk, CL
1, CL2, CLt; CLy to CLk, CL1 to CL
It is temporarily adsorbed and held by 3). Cleaning work starting means (C6) of the cleaning work control means (C6)
In A), the cleaning work is started at the set timing. The cleaning work executing means (C6B) is configured to operate the toner adsorption holding members (CLp, CLt; CLy to CL).
k, CLt; CLy to CLk, CL1, CL2, CL
t: CLy to CLk, CL1 to CL3), the toner adsorbed and held on the toner adhering rotary member (PR, B, T2b; P)
y-Pk, B, T2b; Py-Pk, B1-B3, T2
b) and the toner-adhering rotating member (P
R, B, T2b; Py to Pk, B, T2b; Py to P
k, B1 to B3, T2b) surface toner is transferred to the toner adhering rotary member (B; B3; T2b) where the toner is collected by the cleaner (CLb, CLt), and the cleaner (CLb, CL3, CLt) is transferred. Perform a cleaning operation to collect the toner. The cleaning operation ending means (C6C) ends the cleaning operation according to the detected density signal of the toner density sensor (SN1).

When the cleaning operation is completed in response to the detected density signal of the toner density sensor (SN1),
The cleaning operation can be terminated when the detected toner density value becomes a certain value or less. Further, it is possible to configure so that the cleaning operation is ended after a set period of time has elapsed from the time when the value of the detected toner density becomes a certain value or less. The set period can be configured to be shortened or extended according to set conditions. Further, when the ratio between the detected density of the toner density sensor SN1 before starting the cleaning operation and the detected density after the cleaning operation is started and the density of the discharged toner is detected, or when there is a difference within a certain range, cleaning is performed. It can be configured to finish the work. By adopting such a configuration, it is possible to prevent the cleaning from being performed for an unnecessarily long time and prevent the deterioration of the image recording efficiency. In the present invention, the toner density sensor SN1 can also be used as a sensor for reading the image density of the patch image for adjusting the image density.

The position of the toner density sensor SN1 can be adjusted in the main scanning direction perpendicular to the paper feed direction, and the distribution of the number of writing dots in the main scanning direction is detected during image recording to determine the number of writing dots. Position with the largest number (position in main scanning direction)
It is possible to move the toner concentration sensor SN1 to detect the toner concentration. In this case, in general, the toner density at the toner density detection position becomes the highest, so when the toner density at that position becomes less than or equal to a predetermined value, the cleaning is terminated, so It is also possible to make the toner density at a place below the predetermined value. When the maximum value of the density detected by the toner density sensor SN1 during the cleaning operation is small, it is possible to lengthen the interval until the start of the next cleaning operation.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiments) Next, specific examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. Absent. (Embodiment 1) FIG. 1 is an overall explanatory view of Embodiment 1 of an image forming apparatus of the present invention. In FIG. 1, the image forming apparatus U is
An automatic document feeder U1 and an image forming apparatus main body (copier) U2 having a platen glass PG supporting the automatic document feeder U1 are provided. The automatic document feeder U1 has a document feed tray T on which a plurality of documents Gi to be copied are stacked and placed.
G1 and the original feed tray TG1 to the platen glass P
It has a document discharge tray TG2 from which a document Gi conveyed through a copy position (document reading position) on G is discharged. The image forming apparatus main body U2 has a UI (user interface) through which a user inputs and operates an operation command signal such as copy start, an exposure optical system A, and the like. Reflected light from a document transported on the platen glass PG by the automatic document transport device U1 or a document (not shown) manually placed on the platen glass PG is transmitted through the exposure optical system A to a CCD ( R (red), G (green),
It is converted into a B (blue) electric signal. An IPS (image processing system) outputs the RGB electrical signals as Y signals.
(Yellow), M (magenta), C (cyan), K
It is converted into (black) image data and temporarily stored, and the image data is output to the laser drive circuit DL at a predetermined timing.

The surface of the drum-shaped photosensitive member PR that rotates and moves in the direction of the arrow Ya is uniformly charged by the charging roll (charging member) CR, and the latent image forming position Q1, the developing area Q2, and the primary transfer area Q3. Sequentially pass through.

A ROS (latent image forming device) driven by the laser drive circuit DL exposes and scans the surface of the photoconductor PR at the latent image forming position Q1 by the laser beam L, and an electrostatic latent image is formed on the surface of the photoconductor PR. To form. When forming a full-color image, electrostatic latent images corresponding to four-color images of Y (yellow), M (magenta), C (cyan), and K (black) are sequentially formed, and in the case of a monochrome image, K is formed.
Only the electrostatic latent image corresponding to the (black) image is formed. To write the latent image on the photoconductor PR by the laser beam L, the belt position sensor SNb is set by using the reference mark Bm (see FIG. 1) provided on the non-image portion of the intermediate transfer belt (intermediate toner image carrier) B described later. Is started after a lapse of a predetermined time from detection. When forming a full-color image with the rotary developing device, the respective colors are superposed, so that the time from the detection of the reference mark Bm by the belt position sensor SNb to the start of the latent image writing by the laser beam L is the same for each color. .

The rotary type developing device G is sequentially moved to the developing area Q2 in accordance with the rotation of the rotation shaft Ga, and is rotated Y.
(Yellow), M (magenta), C (cyan), K
It has four (black) color developing devices GY, GM, GC and GK. The developing devices GY, GM, GC, and GK for the respective colors have a developing roll GR that conveys the developer to the developing area Q2, and the electrostatic latent image on the photoconductor PR passing through the developing area Q2 is tonered. The image Tn is developed. The toner image forming device (PR + CR + ROS +) is formed by the photoconductor PR, the charging roll CR, the ROS (latent image forming device), the developing device G, and the like.
G) is configured.

Below the photoconductor PR, a pair of left and right slide rails SR, SR are used to form a slide frame F1 (2
It is supported so as to be slidable back and forth (direction perpendicular to the image plane). A belt frame F2 of the belt module BM is supported on the slide frame F1 so as to be vertically rotatable around a hinge shaft F2a. The belt module BM includes a plurality of belt support rolls (Rd, Rt, Rf, T2a) that rotatably support the intermediate transfer belt (transfer toner image carrier) B, a primary transfer roll T1, and a contact roll. It has T2c and the belt frame F2 that supports them. The plurality of belt support rolls (Rd, Rt, Rf, T2a)
Includes a belt driving roll Rd, a tension roll Rt, an idler roll (free roll) Rf and a backup roll T2a, and the contact roll T2c is in contact with the backup roll T2a.

The belt module BM is rotatable up and down around the hinge shaft F2a, and when it is rotated downward, the belt module BM does not come into frictional contact with the photoconductor PR together with the slide frame F1. Body U2
You can get in and out of. The primary transfer roller T1 configured as the primary transfer device receives the toner image Tn on the surface of the photoconductor PR when a transfer voltage having a polarity opposite to the charging polarity of the toner is applied by the power supply circuit E controlled by the controller C.
Is primarily transferred to the intermediate transfer belt B in the primary transfer area Q3. In the case of a full-color image, the toner images Tn of the respective colors sequentially formed on the surface of the photoconductor PR are primary-transferred one after another on the surface of the intermediate transfer belt B in the primary transfer area Q3, and finally, a full-color multiple toner image. Are formed on the intermediate transfer belt B. When forming a monochromatic monocolor image, only one developing device is used, and the monochromatic toner image is primarily transferred onto the intermediate transfer belt B. After the first transfer,
The surface of the photoconductor PR is destaticized by the destaticizing roll JR, and the residual toner is cleaned by a brush-shaped photoconductor toner adsorption holding member CLp configured as a photoconductor cleaner.

Below the backup roll T2a, a secondary transfer slide frame Fs slidable forward and backward (a direction perpendicular to the paper surface) by a pair of left and right slide rails SR, SR is provided with respect to the main body U2 of the image forming apparatus. It is detachably supported. A secondary transfer elevating frame Ft of the sheet transfer unit Ut is supported on the secondary transfer slide frame Fs so as to be vertically rotatable around a hinge axis Fta. The sheet transfer unit Ut can be moved in and out of the image forming apparatus main body U2 without being in frictional contact with the belt module BM in a state of being rotated downward.
The sheet transfer unit Ut includes a secondary transfer roll (that is, a sheet transfer roll that transfers toner to a recording sheet) T2b, a brush-shaped roll toner suction holding member CLt configured as a secondary transfer roll cleaner, and a roll. Support lever Lr, post-transfer sheet guide SG2,
The sheet transport belt BH and the secondary transfer elevating frame Ft that supports the sheet transport belt BH are provided.

The roll support lever Lr is a lever for supporting the secondary transfer roll (sheet transfer roll) T2b and the roll toner suction holding member CLt, and is rotated around a hinge axis La by a motor (not shown) or the like. The secondary transfer roll T2b is moved between a secondary transfer area that contacts the intermediate transfer belt B and a standby position that is separated from the intermediate transfer belt B. The secondary transfer roll T2b
A secondary transfer area Q4 is formed by the contact area of the intermediate transfer belt B, and the secondary transfer roll T2b, the backup roll T2a, and the contact roll T2.
The secondary transfer device T2 is constituted by c. The intermediate transfer belt B, the primary transfer device T1, and the secondary transfer device T2 constitute a transfer device (B + T1 + T2) that transfers the toner image on the surface of the photoconductor PR to the recording sheet S.

The recording sheets S stored in the paper feed tray TR1 are taken out by the pickup roll Rp at a predetermined timing, separated one by one by the separating roll Rs, and conveyed to the registration roll Rr. The cash register roll Rr
The recording sheet S conveyed to the pre-transfer sheet guide S is timed to move the primary-transferred multiple toner image or single-color toner image to the secondary transfer area Q4.
It is conveyed from G1 to the secondary transfer area Q4. When the recording sheet S passes through the secondary transfer area Q4, the secondary transfer device T2
A secondary transfer voltage having the same polarity as the charging polarity of the toner is applied to the contact roll T2c from the power supply circuit E controlled by the controller C. The secondary transfer device T2 secondarily transfers the color toner images, which are primary-transferred overlappingly on the intermediate transfer belt B, to the recording sheet S collectively in the secondary transfer area Q4. Therefore, the toner image forming device (P
R + CR + ROS + G) and the transfer device (B + T1)
+ T2), a toner image is formed on the toner image forming surface of the recording sheet S.

On the intermediate transfer belt B after the secondary transfer, the residual toner is collected by the belt cleaner CLb. Further, the toner adhering to the surface of the secondary transfer roll T2b is primarily adsorbed and held by the roll toner adsorbing and holding member CLt. The secondary transfer roll T2b and the belt cleaner CLb are arranged so as to be able to separate from and contact (separate and contact) with the intermediate transfer belt B, and when a color image is formed, an unfixed toner image of the final color is formed. On the intermediate transfer belt B 1
It is separated from the intermediate transfer belt B until the next transfer. The roll toner suction holding member CLt is
The contact and separation movement is performed together with the secondary transfer roll T2b. The recording sheet S to which the toner image is secondarily transferred is conveyed to the fixing area Q5 by the post-transfer sheet guide SG2 and the sheet conveying belt BH. The fixing area Q5 includes a heating roll (fixing heating rotating member, recording sheet holding rotating member) Fh and a pressure belt (fixing pressing rotating member, recording sheet holding rotating member) Fp (a pair of recording sheet holding rotating members Fh and Fp) is a region formed by a pressure contact region (recording sheet holding portion). The recording sheet S has the heating roll Fh and the pressure belt Fp when passing through the fixing area Q5.
It is heated and fixed by a fixing device F having The recording sheet S on which the toner image is fixed is recorded on the recording sheet discharge tray TR.
Emitted to 2. The symbols Rp, Rs, Rr, SG1, S
The sheet conveying device SH is constituted by the elements indicated by G2 and BH.
(Rp, Rs, Rr, SG1, SG2, BH) are configured.

(Belt cleaner CLb) FIG.
2A is a diagram showing the belt cleaner shown in FIG. 2A, showing the state in which the belt cleaner is in contact with the intermediate transfer belt and has moved to a cleaning position for cleaning the toner on the intermediate transfer belt. FIG. It is a figure which shows the state which moved to the standby position separated from the belt. In FIG. 2, the belt cleaner CLb is arranged so as to face the portion of the intermediate transfer belt B wound around the belt drive roll Rd. The belt cleaner CLb
Is a cleaning case 1 which is rotatable about a hinge shaft 1a, a tension spring 2 which operates to rotate the cleaning case 1 in a counterclockwise direction at all times, and the cleaning case 1 is separated from and in contact with the intermediate transfer belt B. It has a cam 3 for making it.

The belt cleaner CLb has a cleaning blade 4 whose edge (tip) contacts the intermediate transfer belt B on the belt driving roll Rd, a cleaning brush 5 rotatably supported in the cleaning case 1, and Metal brush cleaning roll 6
And a scraper member 7 that comes into contact with the surface of the brush cleaning roll 6 and mechanically scrapes the toner from the brush cleaning roll 6, and a toner transport auger 8 that carries the scraped toner to a toner collecting device (not shown). Have

The toner remaining on the intermediate transfer belt (intermediate toner image carrier) B that has passed through the secondary transfer area Q4 is belt cleaner CLb together with the intermediate transfer belt B.
Is transported to the position. The toner remaining on the intermediate transfer belt B receives a mechanical scraping force from the cleaning brush 5 rotating in the direction opposite to the direction of the intermediate transfer belt B, and the adhesion force with the intermediate transfer belt is weakened. The toner whose adhesion has been weakened moves to the cleaning brush 5 by a bias having a polarity opposite to the charging potential of the toner applied to the cleaning brush 5, and the toner that has not moved to the cleaning brush 5 is provided downstream of the cleaning brush. It is scraped off by the blade 2. In the first embodiment, the bias potential of V1 = + 500V is applied to the cleaning brush 5 when the − (minus) charged toner is collected,
When collecting + (plus) charged toner, V2 = -7
A bias potential of 00V is applied.

The toner adsorbed on the cleaning brush 5 is carried to the contact portion with the brush cleaning roll 6 arranged so as to contact the cleaning brush 5. To the brush cleaning roll 6, a bias having a polarity opposite to the charging potential of the toner and having a larger absolute value than the bias applied to the cleaning brush 5 is applied,
The toner reaching the contact portion is cleaned by the cleaning brush 5.
Under the action of an electric field formed between the brush cleaning roll 6 and the brush cleaning roll 6, the electrostatic charge moves to the surface of the brush cleaning roll 6. In the first embodiment, when the − (minus) charged toner is collected on the brush cleaning roll 6 (when the bias potential of V1 = + 500V is applied to the cleaning brush 5), V3 = + 700.
When the bias potential of V is applied and the + (plus) charged toner is collected (when V2 = −700V), V4 is applied.
A bias potential of = -900V is applied. The toner adhered to the brush cleaning roll 6 is mechanically mechanically brushed by a scraper member 7 (see FIG. 2) provided in one direction of the doctor (a direction facing the rotation of the brush cleaning roll) at a position downstream of the contact portion. Scraped from 6. The toner scraped off is cleaned by the cleaning brush 5 and the brush cleaning roll 6.
By the toner conveying auger 8 provided below the
The toner is carried to a toner collecting device (not shown).

(Toner suction holding members CLp and CL
t) FIG. 3 is an enlarged view of a main part of FIG. In FIG. 3, the photoconductor toner attracting / holding member CLp and the roll toner attracting / holding member CLt are brush-like members. The toner attracting / holding member CLp for each photoconductor is
V5 = + 500V when attracting (minus) charged toner and when discharging the attracted and held + charged toner
V is applied when the + (plus) charged toner is attracted and when the − charged toner is discharged.
A bias potential of 2 = -700V is applied. Further, a bias potential of V5 = + 700V is applied to the roll toner adsorption / holding member CLt when adsorbing the − (minus) charged toner and discharging the adsorbed / held + charged toner, and the + (plus) charged toner is V2 = -9 when adsorbing and when discharging charged toner
A bias potential of 00V is applied.

(Explanation of Control Section of First Embodiment) FIG. 4 is an explanatory view of a control section of the first embodiment of the image forming apparatus of the present invention, and is a block diagram of each function provided in the control section (functional block diagram). It is the figure shown with. In FIG. 4, the controller C is an I / O (input / output interface) for inputting / outputting signals to / from the outside and adjusting the input / output signal level,
A ROM (read only memory) in which programs and data for performing necessary processing are stored, a RAM (random access memory) for temporarily storing required data, and a program stored in the ROM. It is configured by a computer having a CPU (central processing unit) that performs processing, a clock oscillator, and the like, and various functions can be realized by executing the programs stored in the ROM.

(Signal Output Element Connected to the Controller C) The controller C is connected to the UI (user interface), the toner concentration sensor SN1, the fixing device temperature sensor SN2, a belt position sensor (not shown), and other signal output elements. The output signal of is input. The UI
Is a display unit UI1, a copy start key UI2, a copy number setting key UI3, a magnification setting key UI4, a ten-key UI
5. Equipped with a sheet type designation key.

(Control element connected to the controller C) The controller C controls the IPS, main motor drive circuit D1, developing device rotation drive circuit D2, heating roll drive circuit D3, power supply circuit E, and other control elements. They are connected and output their operation control signals. The power supply circuit E is a charging power supply circuit E1, a CLp power supply circuit E2,
Development bias power supply circuit E3, intermediate transfer power supply circuit E
4, sheet transfer power supply circuit E5, CLb power supply circuit E
6, a CLt power supply circuit E7, a heater power supply circuit E8, and the like. The main motor drive circuit D1 rotationally drives the main motor M1, and the main motor M1 drives the photoconductor (primary toner image carrier) PR, charging roll CR, intermediate transfer belt (intermediate toner image carrier) B, primary The transfer roll T1 is rotationally driven. The developing device rotation drive circuit D2 rotates the developing device G via the developing device rotation motor M2, and moves the developing devices Gy to Gk of each color to the developing area Q2. The developing roll driving circuit D3 is a developing roll G of each developing unit Gy to Gk via a GR (developing roll) driving motor M3.
Rotate R. Fh (heating roll) drive circuit D4
Drives the heating roll Fh of the fixing device F to rotate through the Fh (heating roll) drive motor M4.

The charging power source E1 applies a charging bias or the like to the charging roll CR (charge roll). CLp
The power supply circuit E2 applies a toner attraction bias and a toner ejection bias for ejecting the attracted and held toner to the toner attraction and holding member CLp for the photoconductor. The developing bias power source E3 applies a developing bias to the developing roll of each developing device D that has moved to the developing area Q2. The primary transfer power source E4 applies a primary transfer bias to the primary transfer roll T1 that primarily transfers the toner image on the surface of the photoconductor (primary toner image carrier) to the intermediate transfer belt (intermediate toner image carrier) B. Apply. The sheet transfer power supply circuit E5 transfers the toner image on the intermediate transfer belt (intermediate toner image carrier) B onto the recording sheet S or transfers the toner on the secondary transfer roll T2b to the intermediate transfer belt (intermediate toner image carrier). ) A transfer bias is applied to the contact roll T2c when it is moved to the surface. The CLb power supply circuit E6 applies a toner collecting bias to the cleaning brush 5 and the brush cleaning roll 6 of the belt cleaner CLb. The CLt power supply circuit E7 applies a toner suction bias and a toner discharge bias for discharging the held toner to the roll toner suction holding member CLt. The heater power supply circuit E8 applies heater driving power to the heater housed inside the heating roll Fh of the fixing device F.

(Function of Controller C) The controller C has a function of executing processing according to an input signal from the signal output element and outputting a control signal to each of the control elements. That is, the controller C has the following functions. C1: Transfer Bias Control Unit The transfer bias control unit C1 applies a transfer bias to the primary transfer device to transfer the toner between the toner image carriers. C2: sheet transfer roll bias control means (sheet transfer device bias control means) The sheet transfer roll bias control means C2 transfers the toner image on the intermediate transfer belt (intermediate toner image carrier) B to the recording sheet S. A bias is applied to the sheet transfer roll.

C3: Toner Adsorption Transfer Control Means The toner adsorption transfer control means C3 has an adsorption bias applying means C3a and a reverse transfer bias applying means C3b.
A bias for toner transfer is applied between the photoconductor (primary toner image carrier) PR and the toner adsorption / holding member CLp for the image carrier. C3a: Adsorption bias applying means C3a The adsorption bias applying means C3a applies an adsorption transfer bias for transferring the toner on the surface of the photoconductor (primary toner image carrier) PR to the toner adsorption holding member CLp. C3b: Reverse transfer bias applying means C3b reversely transfers the toner attracted and held by the toner attracting / holding member CLp for the photoconductor (for the primary toner image carrier) to the photoconductor (primary toner image carrier) PR. Apply reverse transition bias. C4: Cleaner Bias Control Means The cleaner bias control means C4 applies a cleaning bias for collecting the toner on the surface of the intermediate transfer belt (intermediate toner image carrier) B to the belt cleaner CLb, the cleaning brush 5 and the brush cleaning of the belt cleaner CLb. Apply to roll 6.

C5: Toner transfer control means for rolls The toner transfer control means for rolls C5 has an attraction bias applying means C5A and a reverse transfer bias applying means C5b, and a secondary transfer roll T2b and a roll toner attracting / holding member CLt. A bias for toner transfer is applied between and. C5A: Adsorption bias applying means C5A The adsorption bias applying means C5A is a secondary transfer roll T2.
The toner on the surface b of the roll toner adsorption holding member C
A transfer bias for adsorption that transfers to Lt is applied. C5b: Reverse transfer bias applying means C5b applies a reverse transfer bias for reversely transferring the toner attracted and held by the roll toner suction holding member CLt to the secondary transfer roll T2b.

C6: Cleaning work control means. The cleaning work control means C6 has a cleaning work start means C6A, a cleaning work execution means C6B, and a cleaning work end means C6C, and at the set timing, the toner adsorption holding member CLp for the toner image carrier and the roll toner. A toner cleaning operation of transferring the toner held by the suction holding member CLt to the belt cleaner CLb and collecting the toner is performed. C6A: Cleaning Work Starting Means Cleaning work starting means C6A includes a job starting means C6A1 and a continuous printing starting means C6A.
2, the cleaning operation is started at the set timing. C6A1: Start means at job start The start means at job start C6A1 is set under a condition (detected temperature of the fixing device temperature sensor SN2) when a start signal of a job (image forming operation) is input (when a copy start key is input). The cleaning operation is started when Tf and the set temperature Tr of the set image recordable temperature satisfy Tr−Tf ≧ 100 ° C.). C6A2: Continuous Printing Start Unit The continuous printing start unit C6A2 starts the cleaning operation every time the number of continuous print sheets reaches 48.

C6B: Cleaning Work Execution Means The cleaning work execution means C6B uses the reverse transfer bias applying means C3b of the toner adsorption / transfer control means C3 to cause the toner adsorbed and held by the toner adsorbing / holding member CLp for the image carrier. The toner on the surface of the primary toner image carrier PR is reversely transferred to the primary toner image carrier PR and is moved to the intermediate transfer belt (intermediate toner image carrier) B by the transfer bias control means C1 to perform the intermediate transfer. The toner on the surface of the belt (intermediate toner image carrier) B is transferred to the belt cleaner C by the cleaner bias control means C4.
A cleaning operation for collecting Lb is performed.

C6C: Cleaning Work Completion Means The cleaning work completion means C6C is a cleaning toner density detection means C6C1 for detecting the toner density SN1a at the time of cleaning operation, and a cleaning operation completion for storing the toner density threshold value Ns for determining the cleaning operation completion. The toner concentration threshold storage unit C6C2 for determination is provided, and the cleaning operation is terminated when the detected concentration signal SN1a of the toner concentration sensor SN1 is SN1a ≦ Ns with respect to the set threshold Ns. For example, when the toner density is detected at a level of 0 to 255 and the detection value SN1a is 0 to 44, the toner density is 0% and the detection value SN1a is 2
In the case of 21 to 255, if the toner density is 100%,
When the detected value SN1a becomes Ns (= 50) or less (that is, when SN1a ≦ 50), the cleaning operation is ended.

C6C1: Toner concentration detecting means during cleaning The toner concentration detecting means C6C1 during cleaning detects the toner concentration SN1a during the cleaning operation based on the input signal from the toner concentration sensor SN1. C6C2: Toner density threshold storage means for cleaning operation end determination Toner density threshold storage means C for cleaning operation end determination
The 6C2 stores a toner density threshold value Ns for determining the end of the cleaning operation, which is used to determine the timing to stop the cleaning operation during the execution of the cleaning operation.

(Operation of First Embodiment) In the first embodiment of the image forming apparatus having the above-described structure, negative (-) charged toner, that is, negatively charged toner is used. A bias of +500 V is applied to the body toner suction holding member CLp and the roll toner suction holding member CLt to collect the negatively charged toner. These biases are applied by the attracting bias applying means C3A and C5A of the toner attracting and transferring control means C3 and the roll toner transferring control means C5 shown in FIG. When the image forming apparatus is used in such a state, the adsorbed toner is accumulated on the toner adsorbing / holding member CLp for the image carrier and the toner adsorbing / holding member CLt for the roll, and the cleaning performance deteriorates.

Therefore, in the first embodiment, the fixing device detection temperature Tf and the set temperature Tr detected by the fixing device temperature sensor SN2 at the start of the job (that is, when the copy start key UI2 (see FIG. 4) is input) are set. If the following expression (1) is satisfied, cleaning is started. Tr−Tf ≧ T (= 100 ° C.) ………………………………………… (1) That is, when the above formula (1) is satisfied, the time until completion of warm-up (fixing) Heating roll Fh of device F
The time until the heater reaches the fixing possible temperature is considerably long, so the cleaning operation is performed during that time. When the number of continuous prints reaches 48 or more during execution of the job, the job is interrupted and the cleaning operation is performed. When the cleaning operation is performed at the timing as described above, it is possible to prevent the print efficiency from being lowered due to the unnecessary cleaning operation.

When the cleaning operation is executed,
As a timing for ending the operation, there may be a method of executing the cleaning operation for a set time and then ending the cleaning operation. In that case, the cleaning time may be longer than necessary. However, by ending the cleaning operation according to the detected toner concentration as in the first embodiment, it is possible to prevent the cleaning operation from being performed for an unnecessarily long time, and it is possible to prevent a decrease in print efficiency. .

(Timing Chart of Main Parts of First Embodiment) FIG. 5 is a diagram showing an example of a timing chart of operations of main parts at the time of starting a job of the image forming apparatus of the first embodiment. FIG. 6 is a diagram showing an example of a timing chart of operations of other main components at the time of starting a job of the image forming apparatus of the first embodiment. The flowcharts corresponding to the timing charts of FIGS. 5 and 6 will be described later. Reference numerals ta to t shown in FIGS. 5 and 6 and FIG.
The meanings of f, t1, and t2 are as follows. ta: Time required for the toner adsorption / holding member CLp for the image carrier to rotate once. tb: time required for the surface of the photoconductor PR to move from the position of the toner adsorption / holding member CLp for the image carrier (see FIG. 3) to the position of the charging roll CR (see FIG. 3). That is, the time required for the toner discharged from the toner adsorption / holding member CLp for the image carrier to move to the position of the charging roll CR. tc: Time required for the surface of the photoconductor PR to move from the position of the toner adsorption / holding member CLp for the image carrier to the position of the toner density sensor. That is, the toner discharged from the toner adsorption / holding member CLp for the image carrier is the toner concentration sensor SN.
The time it takes to move to position 1.

Td: The time required for the surface of the photoconductor PR to move from the position of the toner adsorption / holding member CLp for the image carrier to the position of the primary transfer device T1. That is, the time required for the toner ejected from the toner adsorption / holding member CLp for the image carrier to move to the position of the primary transfer device T1. te: time required for the toner ejected from the image carrier toner adsorption / holding member CLp to move to the position of the secondary transfer device T2. tf: Time required for the toner discharged from the toner adsorption / holding member CLp for the image carrier to move to the belt cleaner CLb. tg: Time required for the surface of the secondary transfer roll T2b to move from the roll toner adsorption holding member CLt to the secondary transfer area Q4. That is, the roll toner adsorption holding member CL
The time required for the toner discharged from t to move to the secondary transfer area Q4.

T1: toner holding member CL for image carrier
-700V application time to p, that is,-(minus)
Toner ejection time. During this time, the time tc has elapsed from the start time of applying −700 V to CLp, the toner concentration sensor SN1 detects the − (minus) discharge toner concentration on the surface of the photoconductor PR, and then the detected toner concentration is the threshold value. The time until the time when it is detected that
(Time required for CLp to make one rotation) plus time. t2: +50 to the toner adsorption / holding member CLp for the image carrier
0V application time, that is, + (plus) toner discharge time. During this time, the toner concentration sensor SN1 detects the + (plus) ejected toner concentration on the surface of the photoconductor PR after the time tc has elapsed from the start time of + 500V application to CLp,
It is the time obtained by adding the time until the time when it is detected that the detected toner concentration has dropped below the threshold value thereafter and the time ta (the time required for CLp to make one rotation).

In the example of the timing charts shown in FIGS. 5 and 6, when the copy start key UI2 (see FIG. 4) is input, the following operation is performed. (1) The main motor M1 is turned on. (2) The rotation of the polygon mirror of the ROS (not shown), the heating roll Fh, the toner adsorption / holding member CLp for the image carrier, etc. is also started. (3) The bias of −700 V for discharging − (minus) toner is started to the toner adsorption / holding member CLp for the image carrier. (4) The belt cleaner CLb moves to the cleaning position where it contacts the intermediate transfer belt B. This is cam 3 (Fig. 2
(See) rotation.

(5) Roll toner adsorption holding member CLt
The application of a bias of −900V for − (minus) toner discharge is started. (6) The contact roll T2c of the secondary transfer device T2 is
A bias of + 500V for transferring − (minus) charged toner for transferring − (minus) charged toner discharged from the CLt to the surface of the secondary transfer roll T2b is applied. The bias application time of +500 V is tg + t1. (7) The cleaning brush 5 of the belt cleaner CLb ejected from the CLt to the surface of the secondary transfer roll T2b and further transferred to the intermediate transfer belt B- (minus)
A bias of +500 V is applied to collect the charged toner.

(8) In FIG. 6, after the time te elapses after the copy start key UI2 is turned on to the secondary transfer device T2, the negative (-) charge is discharged by the toner suction holding member CLp for the image carrier. The toner reaches the secondary transfer device T2. Therefore, the contact roll T2c of the secondary transfer device T2 is configured such that the − (minus) charged toner discharged at CLp is transferred to the secondary transfer roll after a time te has elapsed since the copy start key UI2 was turned on. To prevent this, a bias of -700V is applied only for time t1,
Further, in order to prevent the + (plus) charged toner from transferring to the secondary transfer roll, + 500V for a time t2.
Bias is applied. (9) In FIG. 6, after the time tf has elapsed since the copy start key UI2 was turned on, the- (minus) charged toner discharged by the toner adsorption / holding member CLp for the image carrier is applied to the cleaning brush 5 of the belt cleaner CLb. To reach. Therefore, a bias of + 500V is applied to the cleaning brush 5 only for the time t1 in order to collect the − (minus) charged toner discharged at CLp after the time tf has elapsed since the copy start key UI2 was turned on. Further, subsequently, a bias of −700 V is applied for a time t2 in order to collect the + (plus) charged toner.

(Description of Flowchart of Cleaning Operation at Job Start of First Embodiment) FIG. 7 is a flowchart of a main routine of a job of the image forming apparatus of the first embodiment. Each ST (step) in the flowchart of FIG.
The process is performed according to the program stored in the ROM of the controller C. Further, this processing is executed by multitasking in parallel with other various processing of the image forming apparatus. In ST (step) 1 of FIG. 7, it is determined whether or not the copy start key is turned on. If no (N), ST1 is repeatedly executed. If yes (Y), move to next ST2. The following process is executed in ST2. (1) Start rotation of the main motor M1, secondary transfer roll rotation drive motor, ROS polygon mirror rotation drive motor, and other motors. That is, warm-up is started. (2) Heating heater built in the heating roll Fh, ROS
Start warming up the laser diode, etc.

In ST3, the heating roll F of the fixing device F
It is determined whether the detected temperature Tf of h and the set temperature Tr of the image recordable temperature are Tr−Tf ≧ T (= 100 ° C.). If yes (Y), move to ST4; if no (N), S
Move to T5. In ST4, the cleaning operation is executed. This ST4 subroutine will be described later.
In ST5, it is determined whether the warm-up is completed. If no (N), ST5 is repeatedly executed. If yes (Y), move to ST6. In ST6, the job (image forming operation) is executed. This image forming operation is performed in the same manner as a normal image forming apparatus operation. During the job execution, the cleaning operation is executed every time the continuous print number reaches 48. When the job in ST6 is completed, the process returns to ST1.

The cleaning operation of ST4 and the execution of the job of ST6 are performed by controlling the toner adsorption / holding member CLp for the image carrier, the primary transfer device T1, the secondary transfer device T2, and the roll toner adsorption. Since the control of the holding member CLt, the control of the belt cleaner CLb, etc. are executed by multitasking (parallel processing), ST5 can be omitted. In that case, directly from ST4 to ST6
However, the printing efficiency will be higher if this is done.

FIG. 8 is a flowchart of the ST4 cleaning operation subroutine shown in FIG. 7, and is a flowchart of the bias control of the toner adsorption / holding member for the image carrier during the cleaning operation. The flowchart of FIG. 8 is executed by multitasking in parallel with other flowcharts. In ST11 of FIG. 8, the following processing is performed. (1) A bias of -700 V is applied to the toner adsorption / holding member CLp for the image carrier to eject the-(minus) charged toner. (2) Turn on the clock timer TM1. In ST12, it is determined whether TM1> tc. TM1
When> tc, the toner discharged in ST11 has reached the position of the toner concentration sensor SN1.
If the answer is NO in ST12, ST12 is repeatedly executed. If yes (Y), move to ST13.

At ST13, the toner concentration sensor SN1
Detection density SN1a and toner concentration setting value Ns are SN1
It is determined whether or not a ≦ Ns. ST14 for no (N)
Move on to. In ST14, it is determined whether TM1 ≧ 5ta. If no (N), the process returns to ST13. ST14
In the case of YES (Y), after the TM1> tc is satisfied (after the discharged (-) charged toner reaches the position of the toner concentration sensor SN1), the toner adsorption / holding member CLp for the image carrier is 5 This means that the rotation time (ta × 5) has elapsed. In this case, even if SN1a ≦ Ns is not satisfied, the process proceeds to ST17.

If YES in ST13, if SN1a≤Ns, the detected toner concentration SN1.
It means that a is equal to or less than the set value (threshold value) Ns. In the case of this yes (Y), it moves to ST15. ST1
In step 5, TM2 = ta is set in the timer TM2.
In ST16, it is determined whether or not the timer TM2 has timed out. If no (N) in ST16, ST
16 is repeatedly executed. If the answer is YES (Y) (time is up), the toner concentration S detected in ST13 is detected.
After N1a becomes the set value (threshold value) Ns or less, time t
It means that “a” has elapsed (that is, (−) toner has been ejected while CLp makes one further rotation after SN1a ≦ Ns is satisfied). In addition, ST14, ST15
Can be omitted. Yes in ST16 (Y)
In the case of, move to ST17.

In ST17, the following process is executed.
(1) The measured time of the timer TM1, that is, the (−) charged toner discharge execution time t1 is stored in the (−) toner discharge execution time storage memory. (2) A + 500V (+) charged toner discharge bias is applied to the toner adsorption / holding member CLp for the image carrier. In ST18, it is determined whether the measured time TM1 of the timer TM1 is TM1> t1 + ta. If no (N), ST18 is repeatedly executed. ST18
In the case of yes (Y), it takes time t after the + 500V (+) charged toner discharge bias is applied to CLp.
It means that a (the time from the position of CLp to the position of the toner concentration sensor SN1) has elapsed. At this time, the process proceeds to ST19.

At ST19, the toner concentration sensor SN1
Detection density SN1a and toner concentration setting value Ns are SN1
It is determined whether or not a ≦ Ns. ST20 for no (N)
Move on to. In ST20, it is determined whether TM1 ≧ t1 + 5ta. If no (N), the process returns to ST19. S
If YES in T19, TM1> t
Time after which 1 + tc is reached (after the discharged (+) charged toner reaches the position of the toner density sensor SN1), the toner adsorption / holding member CLp for the image carrier is rotated 5 times (ta
It means that x5) has passed. In this case, SN1
Even if a ≦ Ns is not satisfied, the process proceeds to ST23.

In ST19, if YES (Y), if SN1a≤Ns, the detected toner density SN1.
It means that a is equal to or less than the set value (threshold value) Ns. In the case of this yes (Y), it moves to ST21. ST2
At 1, the timer TM3 is set to TM3 = ta.
In ST22, it is determined whether or not the timer TM3 has timed out. If no (N) in ST22, ST
22 is repeatedly executed. If yes (Y) (time up), the toner concentration S detected in ST19 is detected.
After N1a becomes the set value (threshold value) Ns or less, time t
It means that a has elapsed (that is, (+) toner has been ejected for one more rotation of CLp after SN1a ≦ Ns). In addition, ST21, ST22
Can be omitted. Yes at ST22 (Y)
In the case of, move to ST23.

In ST23, the following processing is executed. (1) The time obtained by subtracting the (-) charged toner discharge execution time t1 from the measurement time TM1 of the timer TM1, that is,
The (+) toner discharge execution time t2 is stored in the (+) toner discharge execution time storage memory. (2) +50 to the toner adsorption / holding member CLp for the image carrier
The application of the 0 V (+) charged toner discharge bias is stopped. Next, the process returns to ST5 of the main routine of FIG. In addition,
As described above, ST5 can be omitted. If ST5 is omitted, the process returns to ST6.

FIG. 9 is a flowchart of the ST4 cleaning operation subroutine shown in FIG. 7, and is a flowchart of the bias control of the intermediate transfer roll during the cleaning operation. The flowchart of FIG. 9 is executed by multitasking in parallel with other flowcharts. S in FIG.
At T31, it is determined whether TM1> td. ST31
In, the measured time TM1 of the timer TM1 is TM1> td
Judge whether or not. If no (N), ST31 is repeatedly executed. If yes (Y) in ST31,
-700V is applied to the toner attracting / holding member CLp for the image carrier.
Time td from application of the (-) charged toner discharge bias (time until the (-) charged toner discharged at CLp moves from the position CLp to the position of the primary transfer unit T1)
Has passed. At this time, the process proceeds to ST32.

At ST32, the primary transfer unit T1 is +50.
By applying 0 V, the (−) charged toner on the surface of the photoconductor (primary toner image carrier) PR is primarily transferred to the intermediate transfer belt B. In ST33, it is determined whether or not TM1 ≧ td + t1. If no (N), ST33 is repeatedly executed.
If YES in ST33, TM1 ≧
After td (toner adsorption / holding member CL for image carrier)
This means that the time t1 has elapsed since the (−) charged toner ejected at p reached the position of the primary transfer device T1. At this time, the (+) charged toner ejected by the toner adsorption / holding member CLp for the image carrier reaches the position of the primary transfer device T1. In this case, the process proceeds to ST34.

At ST34, the primary transfer unit T1 is set to -70.
Applying 0V (+) charged toner transfer bias,
PR of (+) charged toner to photoconductor (primary toner image carrier)
To the intermediate transfer belt B. T in ST35
It is determined whether M1 ≧ td + t1 + t2. In the case of no (N), ST35 is repeatedly executed. If YES in ST35, after TM1 ≧ td + t1 is satisfied (after the (+) charged toner ejected by the toner adsorption / holding member CLp for the image carrier reaches the position of the primary transfer unit T1. ) It means that time t2 has elapsed. At this time, the (+) charged toner ejected to the photoconductor (primary toner image carrier) PR by the toner adsorption / holding member CLp for the image carrier is transferred to the intermediate transfer belt B by the primary transfer device T1. become. In this case, the process proceeds to ST36. ST3
At 6, the primary transfer bias for the (+) charged toner of the primary transfer device T1 is stopped. Next, the process returns to ST5 of the main routine of FIG. As described above, ST5 can be omitted. If ST5 is omitted, the process returns to ST6.

FIG. 10 is a flowchart of a subroutine of the ST4 cleaning operation of FIG. 7 and is a flowchart of bias control of the secondary transfer roll and the toner adsorption / holding member for the roll during the cleaning operation. This FIG.
6 corresponds to the time chart of the applied bias of CLt and the applied bias of the contact roll T2c in FIG. The flowchart of FIG. 10 is executed by multitasking in parallel with other flowcharts. Further, in the first embodiment, the toner discharge processing of the roll toner suction holding member CLt is performed in synchronization with the toner discharge processing of the image carrier toner suction holding member CLp, but it may be performed without synchronization. Is also possible.
In ST41 of FIG. 10, the following processing is performed. (1) A bias of -900V is applied to the roll toner adsorption / holding member CLt in order to eject the-(minus) charged toner. (2) The secondary transfer roll (sheet transfer device) T2b is grounded. (3) A transfer bias of +500 V is applied to the contact roll T2c.

In ST42, it is determined whether or not the application of the +500 V (+) charged toner discharge bias to the toner adsorption / holding member CLp for the image carrier is started. No (N)
In this case, ST42 is repeatedly executed. If yes (Y), the process moves to ST43. In ST43, the discharge of the (+) charged toner of the roll toner suction holding member CLt is started in synchronization with the start of the discharge of the (+) charged toner of the toner suction holding member CLp for the image carrier. + 700V is applied to the holding member CLt. Then S
At T44, it is determined whether TM1 ≧ tg + t1. If no (N), ST44 is repeatedly executed. In the case of yes (Y), since the (+) charged toner discharged from CLt to the secondary transfer roll T2b has reached the secondary transfer area Q4, the (+) charged toner is transferred to the intermediate transfer belt B. Need to be transferred. If yes (Y), the process moves to ST45. In ST45, a (+) charged toner transfer bias of −700 V is applied to the contact roll T2c to move the toner on the secondary transfer roll T2b onto the intermediate transfer belt B.

At ST46, it is determined whether or not the measurement time TM1 of the timer TM1 ≧ tg + t1 + t2. No (N)
In this case, ST46 is repeatedly executed. In the case of yes (Y), the last part of the (+) charged toner discharged from CLt to the secondary transfer roll T2b has passed the secondary transfer area Q4. In the case of this Yes (Y), ST47
Move on to. In ST47, the bias application to the contact roll T2c is stopped. In the processing up to this point, the toner discharge from the roll toner suction holding member CLt and the transfer processing of the discharged toner to the intermediate transfer belt B are completed.
Next, it is necessary to apply a bias for preventing transfer of the toner discharged from the toner adsorption / holding member CLp for the image carrier to the secondary transfer roll T2b side.

At ST48, it is determined whether TM1 ≧ te. If no (N), ST48 is repeatedly executed. In the case of Yes (Y), the (−) charged toner discharged from the image carrier toner adsorption / holding member CLp to the photoconductor (primary toner image carrier) PR has reached the secondary transfer region Q4. become. In this case, the process proceeds to ST49. ST4
9, in order to prevent the (−) charged toner on the intermediate transfer belt B from transferring to the secondary transfer roll T2b, a transfer prevention bias of + 500V is applied to the contact roll T2c. In ST50, it is determined whether or not TM1 ≧ te + t1. If no (N), ST50 is repeatedly executed. In the case of Yes (Y), the (+) charged toner ejected from the image carrier toner adsorption / holding member CLp to the photoconductor PR has reached the secondary transfer area Q4, and therefore the (+) charged toner is used. Must be prevented from being transferred to the secondary transfer roll T2b. If yes (Y), the process moves to ST51.

At ST51, the contact roll T2
A (+)-charged toner transfer prevention bias of −700 V is applied to c. TM1 ≧ te + t1 + t2 in ST52
Judge whether or not. If no (N), ST52 is repeatedly executed. In the case of Yes (Y), the last part of the (+) charged toner discharged from the image carrier toner adsorption / holding member CLp to the photoconductor PR has passed through the secondary transfer area Q4 (time in FIG. 6). See chart). In the case of this yes (Y), it moves to ST53. In ST53, the bias application to the contact roll T2c is stopped. With the above processing, the bias application control of the secondary transfer device T2 and the roll toner adsorption / holding member CLt during the cleaning operation is completed.

FIG. 11 is a flowchart of the ST4 cleaning operation subroutine shown in FIG. 7, and is a flowchart of the bias control of the belt cleaner CLb during the cleaning operation. The flowchart of FIG. 11 is the same as that of FIG.
It corresponds to the time chart of the brush bias of the cleaner. It should be noted that FIG. 6 shows only the time chart of the cleaning brush of the belt cleaner CLb, and the timing chart of the brush cleaning roll 6 is omitted because the screen space is insufficient. The flowchart of FIG. 11 is executed by multitasking in parallel with other flowcharts. In ST61 of FIG. 11, the following processing is performed. (1) The cam drive motor that rotationally drives the cam 3 (see FIG. 2) is driven to move the cleaner to the cleaning position (the position shown in FIG. 2A). (2) A +500 V (−) charged toner collecting bias is applied to the cleaning brush 5. The (-) charged toner collected at this time is the roll toner adsorption holding member CL.
The toner ejected from t. (3) A + 700V (-) charged toner collecting bias is applied to the brush cleaning roll 6. The (-) charged toner collected at this time is the toner ejected from the roll toner adsorption holding member CLt.

Next, in ST62, TM1 ≧ tg + (t
f-te) + t1 is determined. If no (N), ST62 is repeatedly executed. If yes (Y),
Since the (+) charged toner discharged from the roll toner adsorption / holding member CLt has reached the belt cleaner CLb, it is necessary to transfer the (+) charged toner from the intermediate transfer belt B to the belt cleaner CLb. If yes (Y), the process moves to ST63. In ST63, the following process is executed. (1) A bias of −700V for (+) charged toner is applied to the cleaning brush 5 so that the (+) charged toner on the intermediate transfer belt B (roller toner attracting / holding member CL).
The toner ejected from t) is collected. (2) -900V is applied to the brush cleaning roll 6 to move the toner on the cleaning brush 5 onto the brush cleaning roll 6. The toner transferred to the brush cleaning roll 6 is scraped by the scraper member (see FIG.
(Refer to 7) Scraped by 7 and toner transport auger 8
(See FIG. 2), the toner is carried to a toner collecting device (not shown).

In ST64, it is determined whether or not the measurement time TM1 of the timer TM1 ≧ tg + tf-te + t1 + t2. If no (N), ST64 is repeatedly executed.
If yes (Y), CLt to secondary transfer roll T2b
This means that the last portion of the (+) charged toner discharged to the belt cleaner CLb has reached the belt cleaner CLb. This Jesus (Y)
In the case of, move to ST65. The following process is executed in ST65. (1) Stop applying bias to the cleaning brush 5. (2) Stop applying bias to the brush cleaning roll 6. By the processing up to this point, the roll toner adsorption holding member C
The process of collecting the toner discharged from Lt ends. next,
It is necessary to collect the toner discharged from the toner adsorption / holding member CLp for the image carrier.

At ST66, it is determined whether TM1 ≧ tf. If no (N), ST66 is repeatedly executed. In the case of Yes (Y), the (−) charged toner discharged from the toner adsorption / holding member CLp for the image carrier to the photoconductor (primary toner image carrier) PR has reached the belt cleaner CLb. . In this case, the process proceeds to ST67. S
At T67, the following process is executed to collect the (−) charged toner on the intermediate transfer belt B. (1) A +500 V (−) charged toner collecting bias is applied to the cleaning brush 5 so that the (−) charged toner on the intermediate transfer belt B (toner adsorption / holding member C for image carrier).
The toner ejected from Lp) is collected. (2) + 700V is applied to the brush cleaning roll 6 to move the toner on the cleaning brush 5 onto the brush cleaning roll 6.

Next, in ST68, TM1 ≧ tf + t1
Judge whether or not. In the case of no (N), ST68 is repeatedly executed. In the case of Yes (Y), since the (+) charged toner discharged from the toner adsorption / holding member CLp for the image carrier has reached the belt cleaner CLb, the above (+)
Transfer charged toner from intermediate transfer belt B to belt cleaner CL
It is necessary to transfer to b. If yes (Y), the process moves to ST69. The following process is executed in ST69. (1) A bias of −700V for (+) charged toner is applied to the cleaning brush 5 so that the (+) charged toner on the intermediate transfer belt B (roller toner attracting / holding member CL).
The toner ejected from t) is collected. (2) -900V is applied to the brush cleaning roll 6 to move the toner on the cleaning brush 5 onto the brush cleaning roll 6.

In ST70, it is determined whether or not the measurement time TM1 of the timer TM1 ≧ tf + t1 + t2. No (N)
In the case of, ST70 is repeatedly executed. In the case of Yes (Y), the last part of the (+) charged toner discharged from the image carrier toner adsorption / holding member CLp to the photoconductor PR has reached the belt cleaner CLb. In the case of this yes (Y), it moves to ST70. The following process is performed in ST70. (1) Stop applying bias to the cleaning brush 5. (2) Stop applying bias to the brush cleaning roll 6. By the processing up to this point, the roll toner suction holding member CLt and the image carrier toner suction holding member CLt
The process of collecting the toner discharged from p is completed.

(Embodiment 2) FIG. 12 is an overall explanatory view of an image forming apparatus according to Embodiment 2 of the present invention and corresponds to FIG. 1 of Embodiment 1. In the description of the second embodiment, constituent elements corresponding to those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. This Example 2
Is different from Example 1 in the following points, but is configured similarly to Example 1 in other points. The image forming apparatus of the first embodiment is a color copying machine equipped with a rotary developing device, but the image forming apparatus shown in FIG. 12 is a tandem type color printer. In FIG. 12, the color printer U has a toner dispenser device Ua for supplying toner. Color printer U Y (yellow), M (magenta), C (cyan), K
(Black) toner image forming devices UY, UM, UC, U
K latent image forming device ROSy, ROSm, ROSc, RO
Sk emits a laser beam for image writing according to the laser drive signal of the laser drive circuit DL of each color. The controller C outputs control signals for the laser drive circuit DL and the power supply circuit E.

In FIG. 12, a drum-shaped photosensitive member (primary toner image bearing member) P of the K (black) toner image forming device UK is shown.
Around the k, a charging roll CRk as a charging device, a developing device Gk, a toner adsorption holding member CLk for an image carrier, and the like are arranged. Then, the other toner image forming devices UY, U
M, UC of the photoconductor (primary toner image carrier) Py, P
Also around m and Pc, charging devices CRy, CRm and CRc, and developing devices Gy and G similar to those around the photoconductor Pk, respectively.
m, Gc, toner adsorption holding members CLy, CL for image carrier
m, CLc, etc. are arranged. Toner suction holding members CLk, CLy, CLm, CL for the image carrier of the second embodiment
c is the toner adsorption / holding member C for the image carrier of the first embodiment
It has the same configuration as Lp.

In FIG. 12, the photoconductors (primary toner image bearing members) Py, Pm, Pc and Pk are uniformly charged by the charging rolls CRy, CRm, CRc and CRk, respectively, and then the latent image forming device is formed. ROSy, ROSm, ROS
An electrostatic latent image is formed on the surface by the laser beam output from c and ROSk. The photoconductors Py, Pm, Pc,
The electrostatic latent image on the surface of Pk is the developing device Gy, Gm, Gc, Gk.
Is developed into toner images of Y (yellow), M (magenta), C (cyan), and K (black). The developing devices Gy, Gm, Gc, and Gk are configured to be replenished with toner from toner cartridges (not shown) of the respective colors mounted on the toner dispenser device Ua.

The toner images on the surfaces of the photoconductors Py, Pm, Pc and Pk (see FIG. 12) are transferred to the intermediate transfer belt (intermediate toner image bearing) by the primary transfer rolls T1y, T1m, T1c and T1k as primary transfer devices. A color image is formed on the intermediate transfer belt B by sequentially transferring the images onto the body B. In the case of only black image data, only the K (black) photoconductor Pk and the developing device Gk are used, and only a black toner image is formed. After the primary transfer, photoconductors Py, Pm, Pc, Pk
The residual toner on the surface is the toner adsorption holding member CL for the photoconductor.
It is primarily adsorbed and held by y, CLm, CLc, and CLk.

Photosensitive members Py, Pm, Pc, Pk of the respective colors
The intermediate transfer belt B and the belt drive roll R are located below
d, tension roll Rt, backup roll T2a
A plurality of belt supporting rolls (Rd, Rt, T2a,
Rf, Rw) are arranged. The intermediate transfer belt B is supported by the plurality of belt supporting rolls so as to be rotatable and movable in the arrow Ya direction.

A sheet transfer unit Ut is arranged below the backup roll T2a. Secondary transfer roll (sheet transfer roll) T of the sheet transfer unit Ut
The intermediate transfer belt B is interposed between the backup roll T2a and the backup roll T2a so that the secondary transfer roll T2b can be separated from the backup roll T2a. A next transfer area Q4 is formed. A brush-shaped roll toner suction holding member CLt is in contact with the secondary transfer roll T2b. The roll toner adsorption / holding member CLt of the second embodiment is configured similarly to the roll toner adsorption / holding member CLt of the first embodiment, and has the same operation. Below the intermediate transfer belt B, the paper feed tray TR1 and the paper feed tray T are provided.
Sheet conveyance path S for conveying the sheet S taken out from R1
An H1, a sheet circulation path SH2, and a sheet reversal path SH3 are arranged.

Sheets S stored in the paper feed tray TR1
Are picked up by a pickup roll Rp at a predetermined timing, separated one by one by a separating roll Rs,
The sheet is conveyed to the registration roll Rr by the conveying roller Ra on the sheet conveying path SH1. The recording sheet S conveyed to the registration roll Rr is secondarily transferred from the pre-transfer sheet guide SG1 at the same timing as the first-transferred multiple toner image or single-color toner image is moved to the second transfer area Q4. It is transported to the area Q4.

A contact roll T2c is in contact with the backup roll T2a, and when the recording sheet S passes through the secondary transfer area, the contact roll T2c has the same polarity as the charging polarity of the toner at the same timing. A secondary transfer voltage is applied. At this time, the toner image is transferred from the intermediate transfer belt B to the recording sheet S. The rolls T2a to T2c constitute a secondary transfer device T2. The intermediate transfer belt B after the secondary transfer is cleaned by the belt cleaner CLb. The belt cleaner CLb of the second embodiment has the same structure as the belt cleaner CLb of the first embodiment.

The recording sheet S to which the toner image is secondarily transferred is conveyed to the fixing device F through the post-transfer sheet guide SG2 and the conveying belt BH. On the recording sheet S, the toner image is heat-fixed when passing through the fixing area Q5 where the heating rolls Fh and Fp of the fixing device are in pressure contact with each other. Alternatively, the sheet is conveyed to the sheet circulation path SH2. The recording sheet conveyed to the sheet discharge roller Rh is discharged to the sheet discharge tray TR2. Seat circuit SH
The recording sheet conveyed to No. 2 is conveyed to the sheet inversion path SH3 by the switching gate G2, inverted, and then switched back to be retransmitted from the sheet circulation path SH2 to the secondary transfer area Q4 through the registration roll Rr.

(Operation of Second Embodiment) As in the first embodiment, the color printer U of the second embodiment having the above-described configuration has the same structure as that of the first embodiment when each photoconductor (primary toner image carrier) is operated during the job (image forming operation). ) The toner adhering to the surface of Py, Pm, Pc, Pk is the toner adsorption holding member CLk, CLy, C for the image carrier.
It is temporarily adsorbed and held by Lm and CLc. Also, 2
The toner adhering to the surface of the next transfer roll T2b is temporarily adsorbed and held by the roll toner adsorbing and holding member CLt. The belt cleaner CLb is the intermediate transfer belt B.
The toner adhering to the surface is collected.

The toner attracted and held by the image carrier toner attracting and holding members CLk, CLy, CLm and CLc and the toner attracted and held by the roll toner attracting and holding member CLt at the time of the job are the same as those in the first embodiment. At the time of the cleaning operation executed at the timing, it is discharged in the same manner as in the first embodiment and is collected by the belt cleaner CLb. The timing of ending the toner discharging step in the cleaning operation is the same as in the first embodiment, after the toner densities of the toner density sensors SNy, SNm, SNc, and SNk become equal to or less than the threshold value, the toner adsorption holding member C for the image carrier is further used.
It is said that the time for Ly to CLk to make one rotation has elapsed. Further, the toner ejection period of the second embodiment is similar to that of the first embodiment, even if the detected density of the toner does not fall below the threshold value, the toner adsorption / holding member C for the image carrier.
When the time required for Ly to CLk to rotate 5 times has elapsed, the process ends. The color printer U according to the second embodiment determines the toner discharge period during the cleaning operation based on the toner density detection value, as in the second embodiment. It is possible to prevent the efficiency from decreasing.

(Third Embodiment) FIG. 13 is an overall explanatory view of an image forming apparatus according to a third embodiment of the present invention and corresponds to FIG. 12 of the second embodiment. In the description of the third embodiment,
The constituent elements corresponding to those of the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The third embodiment differs from the second embodiment in the following points, but is configured similarly to the second embodiment in other points. In the image forming apparatus of the second embodiment, the intermediate toner image carrier is composed of the intermediate transfer belt B, but in the image forming apparatus of the third embodiment, two drum-shaped primary intermediate toner image carriers B1. , B2 and one drum-shaped secondary intermediate toner image carrier B3. The primary intermediate toner image carrier B
1, B2 and the secondary intermediate toner image carrier B3 are members having a dielectric layer formed on the surface of a cylindrical aluminum sleeve, and a bias is applied to the aluminum sleeve. Further, in the second embodiment, the charger is composed of the charging rolls CRy to CRk, whereas in the third embodiment, the charger is composed of the charging corotron (discharger) CCy to CCk. In the third embodiment, the toner concentration sensors SNy to SNk of the second embodiment are omitted.

The primary intermediate toner image carrier B1 is a photosensitive member (1
The primary toner image carrier Py, Pm and the secondary intermediate toner image carrier B3 are in contact with each other in the primary transfer areas Qy, Qm.
Then, the photoconductors (primary toner image carrier) Py, Pm
The Y (yellow) and M (magenta) toner images formed on the primary transfer areas Q1y and Q1m are primarily transferred to the primary intermediate toner image carrier B1 in an overlapping manner and then transferred to the intermediate transfer area Q31. The image is transferred to the secondary intermediate toner image carrier B3. The primary intermediate toner image carrier B2 is a photosensitive member (1
The primary toner image carrier Pc, Pk and the secondary intermediate toner image carrier B3 are in contact with each other in the primary transfer areas Qc, Qk.
Then, the photoconductors (primary toner image carrier) Pc, Pk
The C (cyan) and K (black) toner images formed above are 1
In the secondary transfer areas Qc and Qk, the primary intermediate toner image carrier B
In the intermediate transfer area Q32, the secondary intermediate toner image carrier B3 is Y (yellow), M
It is transferred onto the (magenta) toner in an overlapping manner. Y, M, which are transferred and superposed on the secondary intermediate toner image carrier B3
The toner images of the four colors of C and K are the secondary intermediate toner image carrier B
3 is transferred onto the recording sheet S passing through a sheet transfer area Q4 which is a pressure contact area between the third transfer roller T2 and the secondary transfer roller T2.

The primary intermediate toner image bearing members B1 and B
The toner adsorption / holding member C for the primary intermediate toner image carrier is provided downstream of the intermediate transfer areas Q31 and Q32 in the rotation direction of 2.
L1 and CL2 are arranged. Further, adjacent to the surface of the secondary intermediate toner image carrier B3, the sheet transfer area Q
A toner adsorbing / holding member CL3 for the secondary intermediate toner image bearing member is disposed downstream of the toner feeding / holding member CL4.

In the image forming apparatus according to the third embodiment of the present invention having the above-described structure, the toner discharged from the toner adsorption / holding members CLy, CLm for the image bearing member during the cleaning operation is the photoconductor (primary toner image bearing member). ) Py and Pm are transferred to the primary intermediate toner image carrier B1 and further transferred to the secondary intermediate toner image carrier B3. The toner ejected from the primary intermediate toner image carrier toner adsorption / holding member CL1 to the primary intermediate toner image carrier B1 is transferred to the secondary intermediate toner image carrier B3. The toner discharged from the toner adsorption / holding members CLc, CLk for the image carrier is transferred from the photoconductors (primary toner image carriers) Pc, Pk to the primary intermediate toner image carrier B2, and the secondary intermediate toner image carrier is carried. Transferred to body B3. Further, the toner discharged from the toner suction holding member CL2 for the primary intermediate toner image carrier to the primary intermediate toner image carrier B2 is transferred to the secondary intermediate toner image carrier B3. The toner transferred to the secondary intermediate toner image carrier B3 and the toner ejected from the secondary intermediate toner image carrier toner attracting / holding member CL3 are the secondary transfer roll T2.
b is transferred to the surface. The secondary transfer roll (sheet transfer roll) T2b is configured to be cleaned by the roll cleaner CLt. Further, a toner concentration sensor SN1 is arranged on the upstream side of the cleaner CLt in the sheet conveying direction along the surface of the secondary transfer roll T2b.

In the third embodiment shown in FIG. 13, the toner suction holding members CLy to CLk, CL are used during the cleaning operation.
1 to CL3 to toner image bearing members Py to Pk, B1 to B
The toner ejected to No. 3 is transferred to the surface of the secondary transfer roll T2b, the toner concentration is detected by the toner concentration sensor SN1, and cleaned by the cleaner CLt. The color printer U of the third embodiment is the same as that of the second embodiment.
Similarly, the toner discharge period during the cleaning operation is determined based on the toner density detection value. Therefore, it is possible to prevent the useless cleaning operation from being executed and prevent the printing efficiency from decreasing.

(Modifications) Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, but is within the scope of the gist of the present invention described in the claims. Thus, various changes can be made. A modified embodiment of the present invention is illustrated below. (H01) In Examples 1 and 2, the cleaner CLb is configured as a toner adsorption / holding member for temporarily holding toner, and the roll toner adsorption / holding member C in Examples 1 and 2 is used.
It is possible to configure Lt as a cleaner for collecting toner. (H02) In the third embodiment, the toner adsorbing / holding member CL1 for the primary intermediate toner image carrier is configured as a cleaner for collecting toner, and the cleaner CL3 for the intermediate toner image carrying member is used for temporarily adsorbing toner. It can be configured as a member. (H03) In the third embodiment, the roll cleaner CLt can be configured as the roll toner adsorption / holding member, and the secondary intermediate toner image carrier toner adsorption / holding member CL3 can be configured as the toner recovery cleaner. .

[0099]

The image forming apparatus of the present invention described above can achieve the following effects. (E01) The cleaning operation period can be appropriately set by appropriately setting the end time of the cleaning operation. For this reason, it is possible to prevent wasteful cleaning operation and prevent deterioration of print production efficiency.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of a first embodiment of an image forming apparatus of the present invention.

FIG. 2 is an explanatory view of the belt cleaner shown in FIG. 1, and FIG. 2A is a diagram showing a state where the belt cleaner comes into contact with the intermediate transfer belt and moves to a cleaning position for cleaning toner on the intermediate transfer belt. 2B is a diagram showing a state in which the belt cleaner CLb has moved to a standby position separated from the intermediate transfer belt.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is an explanatory diagram of a control part of the first embodiment of the image forming apparatus of the present invention, and is a block diagram (functional block diagram) showing each function of the control part.

FIG. 5 is a diagram illustrating an example of a timing chart of operations of main components at the time of starting a job of the image forming apparatus according to the first embodiment.

FIG. 6 is a diagram illustrating an example of a timing chart of operations of other main components at the time of starting a job of the image forming apparatus according to the first embodiment.

FIG. 7 is a flowchart of a job main routine of the image forming apparatus according to the first exemplary embodiment.

8 is a flowchart of a subroutine of the ST4 cleaning operation of FIG. 7 and is a flowchart of bias control of the toner adsorption / holding member for the image carrier during the cleaning operation.

9 is a flowchart of a subroutine of the ST4 cleaning operation of FIG. 7, which is a flowchart of bias control of the intermediate transfer roll during the cleaning operation.

10 is a flowchart of a subroutine of the ST4 cleaning operation of FIG. 7 and is a flowchart of bias control of the secondary transfer roll and the toner adsorption / holding member for the roll during the cleaning operation.

11 is a flowchart of a subroutine of the ST4 cleaning operation of FIG. 7, which is a flowchart of bias control of the belt cleaner CLb during the cleaning operation.

FIG. 12 is an overall explanatory diagram of an image forming apparatus according to a second embodiment of the present invention and is a diagram corresponding to FIG. 1 of the first embodiment.

FIG. 13 is an overall explanatory diagram of an image forming apparatus according to a third embodiment of the present invention and is a diagram corresponding to FIG. 12 of the second embodiment.

[Explanation of symbols]

B, B1 to B3 ... Intermediate toner image carrier, C1 ... Transfer bias control means, C2 ... Sheet transfer device bias control means, C3 ... Toner adsorption transfer control means, C3A ... Adsorption bias application means, C3B ... Reverse transfer bias application Means, C4 ... Cleaner bias control means, C5 ... Transfer roll toner adsorption transfer control means, C5A ... Adsorption bias application means, C5B ... Reverse transfer bias application means, C6 ... Cleaning work control means, C6A ... Cleaning work start means, C6B ... Cleaning work executing means, C6C ... Cleaning work ending means, CLb, CL3 ... Cleaner, CLp, CLy to CLk, CL1, CL2 ... Toner suction holding member, CLt ... Transfer roll toner suction holding member, PR, B; Py -Pk, B; Py-Pk, B1-B3 ...
Toner image carrier, PR, Py to Pk ... Primary toner image carrier, S ... Recording sheet, SN1 ... Toner density sensor, T2 ... Sheet transfer device, T2b ... Sheet transfer roll,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/16 103 G03G 21/00 312 21/14 372 F term (reference) 2H027 DA03 DA09 DA12 DA32 DA35 DA38 DA39 DA39 DA44 DD03 DE02 DE07 DE09 EA03 EA09 EA12 EB04 EC06 EC09 EC10 EC18 EC20 ED24 ED25 ED27 EE07 EE08 EF04 EF06 EF09 ZA07 2H030 AA01 AA04 AB02 AD01 AD03 AD17 BB02 B01 H06B01 GA01B01 GA01B01 GA01B01 GA02B01 BB06 GA02B01 BB02 BB02 BB56 BB56 2BB02 BB56 BB56 BB56 BB56 BB56 BB56 BB56 BB02 BB56 BB02 HF14 HF16 JA01 JA05 JA14 KA17 KA20 KA28 KA33 KA40 KB03 KB04 KB05 KB11 KC01 KC02 KF02 KF03 KG04 KG06 KG07 KG08 KH01 KH07 KJ02 2H200 FA01 FA02 GA12 GA14 J02 C29 G02 B22 H08B22 H22B22 H08B02 H02B22 H08 GB02 GB30 GB33 GB33 HA33 HA34 JC18 JC19 JC20 LA12 LB03 LB12 LB18 LB38 LB39 LB40 NA02 NA09 PA03 PA10 PA15 PA18 PA22 PB07 PB19 PB22 PB3 2 PB35 PB39

Claims (6)

[Claims] 1. An image forming apparatus characterized by comprising the following constituent requirements (A01) to (A010), and a toner image formed on a surface of (A01) and a primary member carrying the formed toner image. A plurality of toner image bearing members including a toner image bearing member and an intermediate toner image bearing member onto which a toner image on the surface of the primary toner image bearing member is transferred; (A02) a toner image on the intermediate toner image bearing member Sheet transfer device that transfers to recording sheet,
(A03) A cleaner disposed adjacent to the surface of the intermediate toner image carrier to recover the toner adhering to the surface into a toner recovery container, (A04) disposed adjacent to the surface of the primary toner image carrier. (A05) transfer bias control means for applying a transfer bias for transferring the toner between the respective toner image carriers, (A06) the toner adsorption holding member for temporarily adsorbing and holding the toner adhering to the surface Adsorption bias applying means for applying an adsorption transfer bias for transferring the toner on the surface of the next toner image carrier to the toner adsorption holding member, and the toner adsorbed and held on the toner adsorption holding member by the primary toner image carrier. (A07) Toner on the surface of the intermediate toner image bearing member Cleaner bias control means for applying a cleaning bias for collecting the cleaning bias to the cleaner,
(A08) Sheet transfer device bias control means for applying a sheet transfer bias for transferring the toner image on the intermediate toner image carrier to a recording sheet to the sheet transfer device, (A09) Transferring to the recording sheet by the sheet transfer device A toner concentration sensor for detecting the toner concentration on the surface of the toner image carrier that carries the toner image, and (A010) the reverse transfer bias of the toner adsorption transfer control means for adsorbing and holding the toner adsorbed and held by the toner adsorption holding member. The transfer means reversely transfers the toner to the primary toner image carrier and the toner on the surface of the primary toner image carrier is moved to the intermediate toner image carrier by the transfer bias control means, and the surface of the intermediate toner image carrier is transferred. Cleaning operation for performing cleaning operation for recovering the toner of the same by the cleaner bias control means to the cleaner Cleaning work control means having execution means, cleaning work start means for starting the cleaning work at a set timing, and cleaning work end means for ending the cleaning work in response to a density signal detected by the toner density sensor. 2. The image forming apparatus according to claim 1, further comprising the following constituent features (A011) to (A014).
(A011) The sheet transfer device including a sheet transfer roll that transfers the toner image on the intermediate toner image carrier onto a recording sheet, and (A012) the sheet transfer roll that is disposed adjacent to the surface of the sheet transfer roll. (A013) A toner adsorption holding member for a transfer roll that temporarily adsorbs and holds the toner adhering to the surface, Transfer bias toner transfer control means having a reverse transfer bias applying means for applying a reverse transfer bias for reversely transferring the toner attracted and held by the toner suction holding member to the sheet transfer roll, (A014) By the reverse transfer bias applying means of the transfer transfer toner transfer control means, the toner is held by the toner suction holding member. The transferred toner is reversely transferred to the sheet transfer roll, the toner on the surface of the sheet transfer roll is moved to the intermediate toner image carrier by the sheet transfer device bias control means, and the intermediate toner image is moved by the cleaner bias control means. The cleaning operation executing means for executing a cleaning operation for collecting the toner on the surface of the carrier by the cleaner. And a cleaning operation control means for starting the cleaning operation at a set timing, and a cleaning operation ending means for ending the cleaning operation in accordance with a density signal detected by the toner density sensor. 3. The image forming apparatus according to claim 1, further comprising the following constituent features (A015) and (A016).
(A015) a plurality of primary toner image carriers on which toner images of different colors are formed; and (A016) a plurality of primary intermediate toner image carriers on which toner images are transferred from the plurality of primary toner image carriers. And the toner image on the surface of the plurality of primary intermediate toner image carriers and the toner image on the surface of the plurality of primary intermediate toner image carriers are secondarily transferred. A second intermediate toner image carrier having the secondary intermediate toner image carrier having the cleaner disposed adjacent to a surface thereof; 4. The following constituent elements (A01), (A02 ') to
An image forming apparatus comprising (A04 '), (A05), and (A06') to (A010 '), and a toner image is formed on the surface of (A01) and carries the formed toner image. A plurality of toner image bearing members including a primary toner image bearing member and an intermediate toner image bearing member onto which the toner image on the surface of the primary toner image bearing member is transferred, (A02 ') on the intermediate toner image bearing member A sheet transfer roll for transferring a toner image onto a recording sheet; (A03 ') a cleaner arranged adjacent to the surface of the sheet transfer roll for collecting the toner adhering to the surface into a toner recovery container; A toner adsorbing / holding member which is disposed adjacent to the surface of the toner image carrier and temporarily adsorbs and holds the toner adhering to the surface of the toner image carrier, (A05) transferring the toner between the respective toner image carrier Transfer bias Transfer bias control means for applying, (A06 ') suction bias applying means for applying a suction transfer bias for transferring the toner on the surface of each of the plurality of toner image carriers to the toner suction holding member, and the toner suction holding member (A07 ') toner adsorption transfer control means having a reverse transfer bias applying means for applying a reverse transfer bias for reversely transferring the toner adsorbed and held on the toner image carrier, (A07') cleaning the toner on the surface of the sheet transfer roll with the cleaner Cleaner bias control means for applying a cleaning bias to be collected to (A08 ') transfer roll bias control means for applying a sheet transfer bias for transferring the toner image on the intermediate toner image carrier to a recording sheet to the sheet transfer roll, (A09 ') Toner concentration sensor for detecting toner concentration on the surface of the sheet transfer roll (A01
0 ') The toner attracted and held by the toner attracting and holding member is reversely transferred to the toner image carrier by the reverse transfer bias applying means of the toner adsorption and transfer control means, and
The toner on the surface of the next toner image carrier is moved to the intermediate toner image carrier by the transfer bias control unit, and the toner on the surface of the intermediate toner image carrier is moved to the sheet transfer roll by the bias applying unit for the transfer roll, Cleaning operation executing means for executing a cleaning operation for collecting the toner on the surface of the sheet transfer roll by the cleaner bias control means, cleaning operation starting means for starting the cleaning operation at a set timing, and the toner concentration Cleaning work control means having a cleaning work end means for ending the cleaning work in accordance with a concentration signal detected by the sensor. 5. The following constituent elements (A01 ′), (A02),
(A03 ″), (A04 ″), (A05), (A06 ″), (A
07 ″), (A08), (A09), and (A010 ″), and a plurality of (A01 ′) toner images formed on the surface and carrying the formed toner images. A plurality of toner image bearing members including a primary toner image bearing member and an intermediate toner image bearing member onto which a toner image on the surface of the primary toner image bearing member is transferred, (A02) on the intermediate toner image bearing member A sheet transfer device that transfers a toner image onto a recording sheet,
(A03 ″) A toner image bearing member of the plurality of toner image bearing members, a cleaner is disposed adjacent to the surface of the toner image bearing member, and the toner adhering to the surface is collected in the toner collecting container by the cleaner. (A04 ″) A toner image carrier other than the cleaner-bearing toner image carrier, which is a toner image carrier for temporarily adsorbing and retaining the toner adhering to the surface, is adjacent to the surface. Toner image carrier with a holding member arranged in parallel (A05)
Transfer bias control means for applying a transfer bias for transferring toner between the respective toner image carriers, (A06 ″) transfer for adsorption for transferring the toner on the surface of the toner image carrier with the holding member to the toner adsorption holding member Toner adsorption transfer having an adsorption bias application unit for applying a bias and a reverse transfer bias application unit for applying a reverse transfer bias for transferring the toner adsorbed and held by the toner adsorption holding member to the toner image carrier with the holding member. Control means,
(A07 ″) Cleaner bias control means for applying a cleaning bias for collecting the toner on the surface of the toner image carrier with the cleaner to the cleaner, (A08) A sheet for transferring the toner image on the intermediate toner image carrier to a recording sheet Sheet transfer device bias control means for applying a transfer bias to the sheet transfer device, (A09) Detecting the toner concentration on the surface of the toner image carrier that carries the toner image transferred to the recording sheet by the sheet transfer device. Toner concentration sensor, (A010 ″) The toner attracted and held by the toner attracting and holding member is reversely transferred to the toner image carrier with the holding member by the reverse transfer bias applying means of the toner adsorption and transfer control means, and the holding member. The toner on the surface of the toner image bearing member is cleaned by the transfer bias control means. Cleaning work execution means for carrying out cleaning work by moving to the holding body and collecting toner on the surface of the toner image carrier with the cleaner by the cleaner bias control means, and starting the cleaning work at a set timing Cleaning work control means having a cleaning work start means for carrying out the cleaning work, and a cleaning work end means for ending the cleaning work in response to a detected density signal of the toner density sensor. 6. An image forming apparatus comprising the following constituent features (B01) to (B06); (B01) a plurality of toner adhering rotary members that rotate in contact with each other and onto which toner images adhere. (B02) Toner transfer bias applying means for transferring the toner between the toner adhering rotary members of the plurality of toner adhering rotary members, which rotate in contact with each other, and (B03) At least one of the plurality of toner adhering rotary members. A cleaner for collecting the toner attached to the rotating member, (B
04) A toner adsorbing / holding member for temporarily adsorbing and holding the toner adhering to the toner adhering rotary member other than the toner adhering rotary member whose toner is collected by the cleaner, (B05) any one of the plurality of toner adhering rotary members A toner concentration sensor for detecting the concentration of toner adhering to the surface of one or more toner adhering rotary members, (B06) reversely transferring the toner adsorbed and held by the toner adsorbing and holding member to the toner adhering rotary member, and adhering the toner. Cleaning work executing means for transferring the toner on the surface of the rotating member to the toner adhering rotating member where the toner is collected by the cleaner, and performing cleaning work for collecting the toner by the cleaner, and the cleaning work at a set timing. Cleaning operation starting means for starting and a density signal detected by the toner density sensor Cleaning operation control means and a cleaning operation ending means for ending the cleaning operation according.