JP2003072052A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive color image forming apparatus capable of raising the printing speed and reducing the cost. SOLUTION: This image forming apparatus comprises an image forming means using an electrophotographic method for transferring a toner image on an image carrier body to a transferring material and an image forming means using an inkjet method. A sensor for detecting the tip of the transferring material is disposed in the vicinity of a portion where the transferring material having the toner image transferred by the electrophotographic method and passing through a fixing device is conveyed to the image forming means using the inkjet method. The conveyance speed of the transferring material passing through the image forming means using the inkjet method is controlled by a motor of which the speed can be varied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, which combines an electrophotographic type image forming means and an ink jet type image forming means to enable high speed operation and cost reduction.

[0002]

2. Description of the Related Art Conventionally, there are an electrophotographic color copying machine composed of a scanner and a printer, and a color printer using an ink jet alone. However, although the colorization of the scanner has been advanced with the network and IT, in recent years, Electrophotographic color printers, which take advantage of the high printing speed, have been lagging in terms of cost. Further, although the color printer using an inkjet printer is low in price, it has a problem that it is difficult to operate at high speed and is not suitable for office use.

[0003]

SUMMARY OF THE INVENTION The present invention is a combination of electrophotographic and inkjet image forming means,
It is an object of the present invention to provide an inexpensive color image forming apparatus capable of increasing the printing speed and reducing the cost.

[0004]

The objects of the present invention are achieved by the following constitutions.

(1) In an image forming apparatus having an electrophotographic image forming means for transferring a toner image on an image carrier to a transfer material and an ink jet image forming means, the toner image is transferred by the electrophotographic method. Is
A sensor for detecting the tip of the transfer material is arranged near the transfer material that has passed through the fixing device and reaches the image forming means by the inkjet method, and the transfer speed of the transfer material when passing the image forming means by the inkjet. Is controlled by a speed-variable motor (first invention).

(2) In an image forming apparatus having an electrophotographic image forming means for transferring a toner image on an image carrier to a transfer material, and an ink jet image forming means, the toner image is transferred by the electrophotographic method. Is
When the transfer material that has passed through the fixing device passes through the image forming means of the inkjet method, the transfer material is conveyed at a high speed in a region where a color image is not formed, and at a predetermined conveyance speed in a region where a color image is formed. An image forming apparatus characterized by being conveyed (second invention).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The image forming apparatus of the present invention separates a read image into a color image and a monochrome image, forms the color image by an inkjet system, and forms the monochrome image by an electrophotographic system.

First, the image forming apparatus according to the present invention will be described. In the description of the embodiments of the present invention, the technical scope of the present invention is not limited by the terms used in the present specification.

In the following description of the embodiment,
The image transferred from the intermediate transfer belt to the transfer material is called a first toner image (back surface image), and the image transferred directly from the image carrier to the transfer material is called a second toner image (front surface image).

FIG. 1 is a schematic diagram showing an example of the overall configuration of the image forming apparatus. In the figure, 10 is an image carrier, 11 is a scorotron charger which is a charging unit, 12 is an exposure optical system which is an image writing unit, 13 is a developing unit which is a developing unit, and 14
Is a cleaning device for cleaning the surface of the image carrier 10, 15 is a cleaning blade, 16 is a developing sleeve, 20 is an intermediate transfer belt, 1 is an image forming means,
Image carrier 10, scorotron charger 11, exposure optical system 1
2, a cartridge system composed of the developing device 13, the cleaning device 14, etc., and can be pulled out forward along a guide rail (not shown). Reference numeral 40 is a fixing device, and 70 is an image reading device.

The image carrier 10 comprises a cylindrical metal base made of, for example, an aluminum material and a conductive layer, a-Si, on the outer periphery thereof.
Layer or a photosensitive layer such as an organic photoreceptor (OPC) is formed, and is rotated counterclockwise as indicated by an arrow in the figure with the conductive layer grounded.

The intermediate transfer belt 20 has a volume resistivity of 10 ⁶
It is an endless belt of -10 ¹² Ω · cm, and has a conductive material dispersed in engineering plastics such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy, and has a thickness of 0.1. A seamless belt having a two-layer structure in which a semi-conductive film substrate having a thickness of ˜1.0 mm is coated with fluorine to a thickness of 5 to 50 μm, preferably as a toner filming prevention layer, is provided. In addition to this, a semi-conductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can be used as the base of the belt.

The traveling of the intermediate transfer belt 20 is performed by the rotation of the drive roller 21 by a drive motor (not shown).
A tension roller 22 and a first transfer roller 23 transfer the toner image on the image carrier 10 to the surface of the intermediate transfer belt 20 and the transfer material P. 25 is a separation static eliminator that assists in separating the transfer material P from the intermediate transfer belt 20, 26 is a driven roller, and 27 is a transfer device, which retransfers the toner image on the intermediate transfer belt 20 to the back surface of the transfer material P. Reference numeral 24 is an earth roller provided so as to face the transfer device via the intermediate transfer belt 20. Reference numeral 2 denotes a belt unit, which is composed of an intermediate transfer belt 20, a driving roller 21 which is also a separation roller, a tension roller 22, a driven roller 26, a first transfer roller 23, an earth roller 24, and the like. Can be pulled out.

The fixing device 40 has a first fixing roller 41 and a second fixing roller 42 which are heating means.

Reference numeral 32 is a paper feed cassette, 30 is a delivery roller, 31 is a timing roller, 33 is a transfer material conveying roller, 34 is a paper charger, and 35 is an earth roller.

A DC voltage having the same polarity as the toner is applied to the paper charger 34, and the transfer material P is charged to have the same polarity as the toner.

The cleaning device 28 has a cleaning blade 29 which can be brought into contact with and released from the intermediate transfer belt 20, and removes the toner remaining on the peripheral surface of the belt after the toner image on the intermediate transfer belt 20 is transferred. remove.

Reference numerals 51, 53, and 54 denote conveyance guides, 60 denotes a front head for color ink jet recording, and 61 denotes a back head. Both heads are horizontally arranged in the main scanning direction (front and back direction of paper), not shown. Slide along the guide. 57 is an ink chamber. 62, 63, 64, 65,
Reference numeral 66 is a conveyance roller, 67 is a paper discharge roller, and 69 is a registration sensor, which detects the leading edge of the transfer material P. The inkjet head 6 for the front surface, the head 61 for the back surface, the transport rollers 64, 65, and the like constitute the inkjet image forming unit 6. 72 is a paper discharge tray.

FIG. 2 is a block diagram of a process relating to image formation. In the figure, S1 is C capable of detecting color information.
A scanner composed of a CD or the like (arranged in the image reading device 70 in FIG. 1), S2 is an image processing unit of the image information read by the scanner S1, and determines whether the original is monochrome or contains color. If it is determined that the color is included, the sub-scanning area including the color is counted, and a command is issued to change the paper feed timing or change the transport speed of the transfer material at the time of creating a color image according to the count. S3 is a laser drive (DRV) that operates the exposure optical system 12 (see FIG. 1) of the image forming unit 1, S4 is a head DRV that operates an inkjet head, and S5 is a sheet feeding / conveying speed during color image formation by inkjet. , A paper feed / transport control unit for controlling paper feed timing, resist timing, inkjet head operation, and the like, and S6 is an interface (PCI-I) for transmitting / receiving read image data to / from a network.
F) and S7 are sensors related to paper feed and conveyance, and S8 is a conveyance speed variable motor.

Next, a technique for color-separating color information by spot color in the case where a red-colored image is included in a document according to the present embodiment will be described with reference to FIG.

FIG. 3A is a block diagram relating to image processing of monocolor original information. In the figure, W1 is a lens, W2 is a CCD, W3 is an A / D converter, and W4 is a color separation table, which is a block for color separation and luminance / density conversion.
In this embodiment, the lens S1, the CCD W2, the A / D converter W3 and the like constitute the scanner S1 (see FIG. 2). The color separation table W4 is included in the image processing unit S2 (see FIG. 2).

The original information passes through the lens W1, the red component transmitted light is supplied to the CCD W2, and the red component signal R
Is output. The signal R is converted into a digital signal Vr in the A / D converter W3 (shading correction is performed at the same time), is supplied to the color separation table W4, and red,
Separated into white and black color signals. The output of the color separation table W4 (which uses a high-speed ROM and has predetermined data written therein) is composed of color code data and density data.

That is, in FIG. 2, the document is read by the scanner S1. The image processing unit S2 counts the number of sub-scanning areas including the color information (red system) of the document, and the information is sent to the paper feed / transport control unit S5 in accordance with the counted numerical value. Variable speed, paper feed timing,
And the timing of ink jet recording are controlled. An image forming command is issued from the image processing unit S2 to the red-type head DRVS4, and print scanning is performed by the front head 60 (see FIG. 1) or the back head 61 (see FIG. 1).

On the other hand, when there is no color information, the image processing unit S2 issues a command for image formation only by the electrophotographic method via the laser DRVS3.

Returning to FIG. 1, the transfer rollers 64 and 6 are provided on the transfer material P on which a monochrome image by an electrophotographic method is placed.
5, an ink jet head 6 for the surface of the ink jet
0 to the back side head 61 performs scanning of red printing. In this case, the transfer material is conveyed at a high speed in the area that does not include the color information where the head scanning is unnecessary, and in the area that includes the color information that requires the head scanning,
The sheet is conveyed at a predetermined conveying speed, or the feeding timing is changed to avoid a rear impact of the transfer material.

The signal of the document information scanned by the scanner S1 (see FIG. 2) is processed by the image processing section S2 and the laser D
After entering the RV S3 (see FIG. 2), as shown in FIG. 1, the image is formed as a toner image on the image carrier 10 by the image forming means 1 through the exposure optical system 12. The toner image is transferred onto the intermediate transfer belt 20 or the transfer material P, and the transfer material P is conveyed toward the inkjet image forming unit 6 via the fixing device.

When there is color information, the transfer material P is sent by the conveying rollers 62 and 63 along the guides 51 and 53, and the transfer sensor P included in the sensors S7 (see FIG. 2) is used to detect the transfer material P. The tip is detected, and the position (registration) with respect to the ink droplet ejection is adjusted.

Further, in FIG. 2, a part of the signals processed by the image processing section S2 is sent to the paper feed / transport control section S5.
The paper feed / conveyance control unit S5 has a function of varying the conveyance speed of the transfer material P when passing through the inkjet image forming unit 6 (see FIG. 1) by controlling the motors S8 of the drive system.

When ink jet printing is performed, the image processing section S2 counts the number of sub-scanning areas containing color information, and linearly counts according to the counted number (as the color printing rate increases). By delaying the paper feed timing from the paper feed cassette 32, it is possible to avoid a rear-end collision with the transfer material printed by the inkjet image forming unit 6.

In FIG. 1, ink is sent from the ink chamber 57 to the front head 60 or the back head 61 by a feeding device (not shown), and nozzles 601 and 611 are used to perform color printing on both sides of the transfer material P. Is discharged to the
Ink is promptly replenished to an ink transfer passage (not shown) from the ink chamber 57 to the nozzles 601 and 611.

In the present embodiment, the process of forming an image by the ink jet of the spot color configuration is described by limiting to the red printing color. However, by the configuration in which a plurality of full color heads are provided, FIG. The image forming process as shown in () is also possible.

When there is no color information, the transfer material passes through the inkjet image forming section 6 at a speed higher than the conveying speed at the time of color image formation, and is discharged to the discharge tray 72 by the discharge roller 67.

FIG. 3B is a block diagram relating to image processing of full-color document information. In the figure, W1 is a lens, W3 is an A / D converter, and W4 is a color separation table, which is a block for color separation and luminance / density conversion. W2, W
5 and W6 are red, green and blue CCD, W7
Is a dichroic mirror.

The document information passes through a lens W1 and is separated by a dichroic mirror W7 into red, green, and blue color separation images, and the transmitted light of each color separation image is C.
It is supplied to CDW2, W5, W6, and the respective signals R,
G and B are output. The signals R, G, B are converted into digital signals Vr, Vg, Vb by the A / D converter W3 (shading correction is performed at the same time), and are supplied to the color separation table W4, where red, green, blue, white, Separated into black color signals. Color separation table W4 (High speed ROM
Is used and predetermined data is written), the output is composed of color code data and density data. The color separation table W4 is included in the image processing section S2 (see FIG. 2), and image formation is performed by the same control as in the case of the monocolor image formation process described above.

As described above, according to the present invention, when the original does not include color information, the image formation is performed only by the electrophotographic image formation process capable of high-speed processing, and the image is transferred to the transfer material to be fixed and discharged. Although it is completed in the paper process, when the color information is included, the transfer material that has undergone the electrophotographic process is conveyed at a predetermined conveying speed to add a color image by the ink jet method, and the color information is not included. In the area, since the transfer material is conveyed at a high speed, the printing speed is increased, and at the same time, the inkjet method can be adopted for the color, so that the cost can be reduced.

Next, the image forming process (image forming step) will be described with reference to FIG. The scorotron charger 11 applies a potential to the image carrier 10 which starts to rotate when image recording is started.

Then, image writing is started on the image carrier 10 through the exposure optical system 12 in response to the image signal from the image reading device 70, and an electrostatic latent image corresponding to the original image is formed. The electrostatic latent image is reversely developed by the developing device 13.

The toner image formed on the image carrier 10 is transferred onto the intermediate transfer belt 20 as a first toner image by the first transfer roller 23 to which a DC voltage having a polarity opposite to that of the toner is applied. After that, the image carrier 10 is cleaned by the cleaning device 14, and the next image forming cycle is started. On the other hand, the transfer material P is the cassette 32.
Is fed by the feed roller 30, is fed to the timing roller 31 via the transfer material feeding roller 33, is fed by the driving of the timing roller 31, and is charged to the same polarity as the toner by the paper charger 34, and the intermediate transfer belt is fed. 20 is synchronized with the first toner image on 20 (the cleaning blade 29 is released from contact when the first toner image passes through the cleaning device 28), and is superimposed on the first toner image. It is fed to the area of the first transfer roller 23 in a sucked state.

After the first toner image is transferred onto the intermediate transfer belt 20, the second toner image is formed on the image carrier 10 which has entered the next image forming cycle, and the second toner image is
In synchronization with the transfer material P superimposed on the first toner image on the intermediate transfer belt 20, the first transfer roller 23 to which a voltage having a polarity opposite to that of the toner is applied is directly transferred to the surface of the transfer material P. .

Further, the transfer material P is supported and conveyed by the intermediate transfer belt 20 and is subjected to the action of the transfer device 27. As a result, the first toner image on the intermediate transfer belt 20 is retransferred to the back surface of the transfer material P, and the transfer processing on both the front and back surfaces is completed. The transfer material P on which the toner images are placed on the front and back surfaces is subjected to the charge removal action of the separation charge eliminator 25, is then curvature-separated from the intermediate transfer belt 20 by the curvature separation portion KT of the drive roller 21, and is conveyed to the fixing device 40. .

Thereafter, the intermediate transfer belt 20 is cleaned by the blade 29 which is in contact with the intermediate transfer belt 20.

In the fixing device 40, the toner image on the transfer material P is melted by applying heat and pressure while nipping and transferring the transfer material P at the nip portion T between the first fixing roller 41 and the second fixing roller 42. After fixing, the image formation on both front and back surfaces of the transfer material P is completed.

When a color image is added to a monochrome image, the transfer material P that has passed through the fixing device 40 is conveyed by the conveyance guide 5.
1 is conveyed by the conveyance rollers 62 and 63. Furthermore, the leading edge of the transfer material P is detected by the registration sensor 69, and the transfer material P is synchronized with the color inkjet. The transfer material P is transported to the transport rollers 64 and 65 at a high speed in an area that does not require color scanning and does not include color information, and at a predetermined transport speed in an area that requires inkjet scanning. By the inkjet of the front head 60 or the back head 61 which slides in the main scanning direction (front and back direction of the paper) along a guide (not shown) provided between the transport rollers 64 and 65, color images are transferred onto the transfer material. Printing is performed.

The transfer material P to which the color image is added is sent along the carrying guide 54, and is sent to the paper discharge tray 72 by the paper discharge roller 67.

[0045]

By combining the electrophotographic image forming means and the ink jet type image forming means, it is possible to provide an inexpensive color image forming apparatus capable of increasing the printing speed and reducing the cost of a general document containing a color image.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus.

FIG. 2 is a block diagram of a process related to image formation.

FIG. 3A is a block diagram relating to image processing of mono-color original information. (B) is a block diagram relating to image processing of full-color document information.

[Explanation of symbols]

1 Image forming means 10 Image carrier 2 Belt unit 20 Intermediate transfer belt 40 fixing device 6 Inkjet image forming section 60 Surface head 61 Back head

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/36 G03G 21/00 372 3F049 21/14 382 F term (reference) 2C055 KK00 KK05 KK06 2C056 EA30 EB12 EB26 EB58 EC12 EC31 EC80 EE06 EE08 2C058 AB03 AC07 AC08 AC12 AC14 AD01 AE02 AE09 AF04 AF12 AF15 AF18 AF20 AF23 GA08 GB01 GB14 GB31 GB47 GC01 GE01 GE20 GE23 GF00 2H027 CA02 ED02 A02 A029A02 A02 A029A02 3F049 AA10 EA10 EA22 EA24 EA28 LA01 LB01

Claims (6)

[Claims] 1. An image forming apparatus having an electrophotographic image forming means for transferring a toner image on an image carrier onto a transfer material and an ink jet image forming means, wherein the toner image is transferred by the electrophotographic method. A sensor for detecting the front end of the transfer material is arranged in the vicinity of the transfer material that has passed through the fixing device and reaches the image forming means by the inkjet method, and the transfer material is conveyed when passing through the image forming means by the inkjet. An image forming apparatus characterized in that the speed is controlled by a variable speed motor. 2. The image forming apparatus according to claim 1, wherein the image forming unit of the ink jet system is for full color having a plurality of heads. 3. The image forming apparatus according to claim 1, wherein the image forming unit of the ink jet system is a spot color having one kind of head whose print color is limited. 4. The image forming apparatus according to claim 3, wherein the spot colors correspond to each other by a technique of color-separating color information. 5. An image forming apparatus having an electrophotographic image forming means for transferring a toner image on an image carrier onto a transfer material and an ink jet type image forming means, wherein the toner image is transferred by the electrophotographic method. When the transfer material that has passed through the fixing device passes through the image forming means of the inkjet method, the transfer material is conveyed at a high speed in a region where a color image is not formed, and a predetermined conveying speed in a region where a color image is formed. An image forming apparatus characterized in that the image forming apparatus is conveyed by. 6. The image forming apparatus according to claim 5, wherein in the area where the color image is formed, the number of sub-scanning areas by inkjet is counted, and the paper feed timing is changed according to the counted numerical value. .