JP2014094808A - Automatic document feeder - Google Patents

Abstract

An automatic document feeder capable of shortening the time interval for each paper feed is provided.
A document is fed to a registration roller, and the document that has reached the registration roller is fed to a position in front of the document reading unit by the registration roller. Then, the document that has reached the position in front of the document reading unit is conveyed to the discharge port through the document reading unit, and the next document is fed before the trailing edge of the document being conveyed passes the registration roller. Start paper.
[Selection] Figure 6

Description

  Embodiments described herein relate generally to an automatic document feeder mounted on an image forming apparatus.

  An automatic document feeder mounted on an image forming apparatus such as an MFP (Multifunction Printer) picks up documents placed on a paper feed tray one by one and supplies them to a registration roller. The document is conveyed to the front position of the reading unit, and the document that has reached the front position of the document reading unit is conveyed through the document reading unit of the MFP main body to the discharge port.

JP 2006-247873 A

  With the recent improvement in the image forming speed of the MFP, it is strongly desired to shorten the time interval from feeding a document to feeding the next document.

  An object of the embodiment is to provide an automatic document feeder that can shorten a paper feeding time interval.

  An automatic document feeder according to an embodiment includes a paper feed tray on which a document is placed, a paper feed unit that feeds documents placed on the paper feed tray one by one, and a paper feed by the paper feed unit. A registration roller that feeds a document to be moved to a position in front of the document reading unit, a conveying unit that discharges the document that has reached the position in front of the document reading unit through the document reading unit, and a document that is being conveyed by the conveying unit Control means for starting the feeding of the next original by the paper feeding means before the trailing end of the registration roller passes.

1 is a perspective view showing an external appearance of an MFP according to an embodiment. 1 is a block diagram of a control circuit of an MFP according to an embodiment. The figure which shows the structure of one Embodiment in cross section. The perspective view which shows the structure of the paper supply means and registration roller of one Embodiment. The perspective view which shows the structure of the conveyance means after the middle part of one Embodiment. The flowchart which shows the control which CPU of one Embodiment performs. The time chart which shows operation | movement of one Embodiment. The figure which shows the conveyance before reading of one Embodiment. The figure which shows the conveyance after a reading & reading of one Embodiment, and the following paper feeding.

Hereinafter, an embodiment will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a composite digital copying machine, so-called MFP (Multifunction printer), which has a plurality of functions such as a copy function, a scan function, and a print function. The MFP 1 includes an automatic document feeder (ADF) 2 that can be opened and closed at a position covering the upper document table. The MFP 1 includes an operation panel 3 including a display and various keys on the front side, and includes a plurality of paper feed cassettes 4 in which sheets of different sizes are accommodated at the bottom.

  A control circuit of the MFP 1 is shown in FIG. A ROM 10, a RAM 12, a hard disk drive (HDD) 13, a network interface 14, an automatic document feeder 2, an operation panel 3, a scanner unit 15, and a print unit 16 are connected to a CPU 10 that is the center of control. The ROM 11 stores various control programs necessary for controlling the MFP 1. The RAM 12 stores various data. The network interface 14 is connected to a communication network such as a LAN. The scanner unit 15 optically reads an image of a document placed on the document table and an image of a document fed from the automatic document feeder 2. The printing unit 16 prints an image read by the scanner unit 15 and an image input via the network interface 14 on a sheet supplied from the sheet feeding cassette 4.

  The automatic document feeder 2 has a CPU 20 as a control unit, and is disposed on the document table 5 and the document reading unit 6 of the MFP 1 as shown in FIG. The document table 5 is formed of a transparent glass plate, the document reading unit 6 is formed of a transparent glass window, and the optical system of the scanner unit 15 is disposed on the lower surface side of the document table 5 and the document reading unit 6.

In FIG. 3, reference numeral 21 denotes a paper feed tray on which a plurality of originals D1, D2,. A pickup roller 22 is disposed at the back of the paper feed tray 21. The pickup roller 22 descends and contacts the documents D1, D2,... And rotates to pick up the documents D1, D2,. The picked-up document D1 enters between the paper feed roller 23a and the driven roller 23b in contact therewith, and is sent to the registration roller 24a upon receiving the rotation of the paper feed roller 23a.
Picking up the document D1 and transporting it to the registration roller 24a is called feeding.
The registration roller 24a temporarily receives the leading edge of the document D1 fed from the paper feeding roller 23a together with the driven roller 24b, and places the leading edge of the document D1 in front of the document reading unit 6 at a predetermined timing considering the scanning operation of the MFP1. Feed to position. When the document D1 is transported by the registration roller 24a, the intermediate transport roller 25a and the pre-reading roller 26a arranged in a curved transport path from the registration roller 24a to the document reading unit 6 also operate in conjunction with each other. A driven roller 25b is in contact with the intermediate conveyance roller 25a, and a driven roller 26b is in contact with the pre-reading roller 26a.
Conveying the document D1 from the registration roller 24a to a position in front of the document reading unit 6 is referred to as conveyance before reading. The length L of the conveyance path from the registration roller 24a to the pre-reading roller 26a is set to the same length as or longer than the letter size such as a postcard, which is the minimum document size.

  The document D1 that has reached the position in front of the document reading unit 6 is sent to the document reading unit 6 upon receiving a rotation of the intermediate conveyance roller 25a and the pre-reading roller 26a at a predetermined timing (reading start instruction from the MFP 1). It passes through the document reading unit 6 while being in contact with the glass surface of the reading unit 6. At this time, the image on the document D1 is optically read by the scanner unit 15 through the document reading unit 6.

Along with this conveyance, the rear end portion of the document D1 existing between the registration roller 24a and the driven roller 24b is extracted from between the two rollers. The document D1 that has passed through the document reading unit 6 is subjected to back-up by the rotation of the intermediate conveyance roller 25a and the pre-reading roller 26a, and further receives retraction by the rotation of the post-reading roller 27a disposed downstream of the document reading unit 6. The paper is discharged to a discharge port where the paper discharge roller 28a is disposed. The driven roller 27b is in contact with the post-reading roller 27a, and the driven roller 28b is in contact with the paper discharge roller 28a. The discharge port communicates with the paper discharge tray 29.
Discharging the document D1 that has reached the position before the document reading unit 6 through the document reading unit 6 is referred to as conveyance after reading & reading.

  A reversing flapper 30 and a reversing tray 31 for reversing the document D1 at the time of double-sided reading are disposed at the discharge port. The document D1 reversed by the reversing flapper 30 and reversing tray 31 is again fed by the conveying path from the paper discharge roller 28a to the intermediate conveying roller 25a, and the reversing flapper 32 and the reversing registration roller 33a arranged on the conveying path. It is sent to the document reading unit 6. A driven roller 33b is in contact with the reverse registration roller 33a.

  An empty sensor 41 is disposed in the vicinity of the paper feed tray 21. A length sensor 42 and a registration sensor 43 are arranged on the conveyance path between the paper supply roller 23a and the registration roller 24a. A pre-reading sensor 44 is disposed between the pre-reading roller 26 a and the original reading unit 6.

  An empty sensor 41 that detects whether or not the documents D1, D2,... Are placed on the paper feed tray 21 is disposed in the vicinity of the paper feed tray 21. A length sensor 42 for detecting the length along the conveyance direction of the documents D1, D2,... Is disposed in the conveyance path between the paper feed roller 23a and the registration rollers 24a, and the documents D1, D2,. A registration sensor 43 for detecting whether or not it has reached 24a is arranged. Between the pre-reading roller 26a and the original reading unit 6, a pre-reading sensor 44 for detecting whether or not the originals D1, D2,...

  The positional relationship between the length sensor 42 and the registration sensor 43 is that the position of the length sensor 42 is in front of the position of the registration sensor 43 in the conveyance direction of the documents D1, D2,. These sensors 41, 42, 43, and 44 output an on signal when the documents D1, D2,... Are detected, and output an off signal when the documents D1, D2,. Hereinafter, outputting an ON signal is referred to as ON, and outputting an OFF signal is referred to as OFF.

  FIG. 4 shows the configuration of the sheet feeding means including the pickup roller 22, the sheet feeding roller 23a, the driven roller 23b, and the registration roller 24a and the driven roller 24b.

  That is, the roller 51 is attached to the rotation shaft of the paper feed motor 50, and the roller 51 is engaged with the first one-way clutch 53 and the second one-way clutch 54 via the annular belt 52. The first one-way clutch 53 is connected to a rotation shaft 55 of the paper feed roller 23 a, and the rotation shaft of the pickup roller 22 is engaged with the rotation shaft 55 via an annular belt 56. The second one-way clutch 54 is connected to the rotation shafts 57 of the plurality of registration rollers 24a.

  The first one-way clutch 53 transmits the rotational force (power of the paper feed motor 50) to the rotary shaft 55 when the paper feed motor 50 rotates forward and the belt 52 rotates in the direction of the solid line arrow. When the belt 50 rotates in the reverse direction and the belt 52 rotates in the direction of the broken line arrow, the rotational force is not transmitted to the rotating shaft 55. Therefore, only when the paper feed motor 50 rotates in the forward direction, the power is transmitted to the paper feed roller 23a via the first one-way clutch 53 and the rotary shaft 55, and the paper feed roller 23a rotates in the direction of the arrow so that the document D1 Feed paper. Further, the rotation of the paper feed roller 23a at this time is transmitted to the pickup roller 22 via the belt 56, and the pickup roller 22 rotates in the direction of the arrow to pick up the document D1.

  The second one-way clutch 54 does not transmit the rotational force (power of the paper feed motor 50) to the rotary shaft 57 when the paper feed motor 50 rotates in the forward direction and the belt 52 rotates in the direction of the solid line arrow. When the paper motor 50 rotates in the reverse direction and the belt 52 rotates in the direction of the broken line arrow, the rotational force is transmitted to the rotating shaft 57. Therefore, only when the paper feeding motor 50 is rotated in the reverse direction, the power is transmitted to the registration roller 24a via the second one-way clutch 54 and the rotating shaft 57, and the registration roller 24a rotates in the direction of the broken line arrow to feed the document D1. I do.

  Further, FIG. 5 shows the configuration of the conveying means after the middle including the intermediate conveying roller 25a, the driven roller 25b, the pre-reading roller 26a, the driven roller 26b, the post-reading roller 27a, the driven roller 27b, the reverse registration roller 33a, and the driven roller 33b. Shown in

  That is, the roller 61 is attached to the rotation shaft of the read motor 60, and the rollers 63 and 64 are engaged with the roller 61 via the annular belt 62. Further, rollers 66 and 67 are engaged with the roller 63 via an annular belt 65. Then, the rotation shaft 71 of the intermediate conveyance roller 25 a is engaged with the roller 66, and the rotation shaft 72 of the pre-reading roller 26 a is engaged with the roller 67. The rotation shaft 73 of the reverse registration roller 33a is engaged with the roller 63, and the rotation shaft 74 of the post-reading roller 27a is engaged with the roller 64. When the read motor 60 operates, the intermediate conveyance roller 25a, the pre-reading roller 26a, the reverse registration roller 33a, and the post-reading roller 27a rotate in the direction of the arrow, respectively, and the original D1 is conveyed.

The CPU 20 of the automatic document feeder 2 has the following means (1) as a main function.
(1) While the document D1 that has reached the position in front of the document reading unit 6 is conveyed through the document reading unit 6 to the discharge port (during conveyance after reading and reading), the trailing edge of the document D1 is registered Control means for starting the feeding of the next document D2 by the paper feeding means before passing through the roller 24a. Specifically, before the trailing edge of the document D1 passes the registration roller 24a, specifically, when the length sensor 42 changes from on to off (when document detection by the length sensor 42 changes from on to off), Or when the document reading unit 6 starts reading, or when a certain time has elapsed from any one of these timings.

Next, control executed by the CPU 20 of the automatic document feeder 2 will be described with reference to the flowchart of FIG. 6 and the time chart of FIG.
When the documents D1, D2,... Are placed on the sheet feed tray 21, the empty sensor 41 is turned on (YES in step 101). When the start button on the operation panel 3 is turned on in this state (YES in step 102), the CPU 20 lowers the pickup roller 22 and causes the paper feed motor 50 to perform forward rotation (step 103). When the paper feed motor 50 rotates in the forward direction, the pickup roller 22 and the paper feed roller 23a rotate, and only one document D1 on the paper feed tray 21 is picked up and fed toward the registration roller 24a.

  When the fed document D1 reaches the registration roller 24a, the registration sensor 43 is turned on (YES in step 104). The CPU 20 transports the leading edge of the document D1 to a position before the document reading unit 6 at a predetermined timing based on the registration sensor 43 being turned on, and reads the document D1 existing at the position before the document reading unit 6 as a document. The process of reading & conveying after reading through the unit 6 to the discharge port is executed (step 105).

  That is, in the pre-read conveyance process, the paper feed motor 50 is rotated in the reverse direction to rotate the registration roller 24a, and then the read motor 60 is operated to rotate the intermediate conveyance roller 25a and the pre-read roller 26a. As shown, the leading edge of the document D1 is conveyed to a position in front of the document reading unit 6.

  In the reading and reading conveyance process, when the leading edge of the document D1 reaches the front position of the document reading unit 6 and the pre-reading sensor 44 is turned on, the operations of the paper feed motor 50 and the read motor 60 are stopped. Then, after waiting for a reading start instruction from the MFP 1 and receiving the reading start instruction, the read motor 60 is operated at a predetermined reading speed according to the resolution of the scanner unit 15, the print magnification, and the like, and the intermediate transport roller 25a, before reading The roller 26a and the post-reading roller 27a are rotated, and as shown in FIG. 9, the document D1 existing at the position in front of the document reading unit 6 passes through the document reading unit 6 and is conveyed to the discharge port. With this conveyance, the rear end portion of the document D1 existing between the registration roller 24a and the driven roller 24b is extracted from between the two rollers. The registration roller 24a and the driven roller 24b are rotated in response to the extraction. The document D1 conveyed to the discharge port is discharged to the discharge tray 29 by the discharge roller 28a.

  On the other hand, the CPU 20 monitors the state of the length sensor 42 with the start of the pre-read conveyance (step 106). Then, when the length sensor 42 changes from on to off, or when the document reading unit 6 starts reading the document D1, or when a certain time elapses from any one of these timings, the CPU 20 The state, that is, the presence or absence of the document on the paper feed tray 21 is confirmed (step 107).

  If the empty sensor 41 is on and there is still a document on the sheet feed tray 21 (NO in step 107), the CPU 20 returns to step 103 and starts feeding the next document D2 as shown in FIG. To do. If the empty sensor 41 is off and there is no document on the paper feed tray 21 (YES in step 107), the process is terminated.

  If the reading speed of the preceding document D1 is slower than the feeding speed of the succeeding document D2, the document D2 may catch up with the document D1 to cause a jam. In such a situation, by securing the above-mentioned fixed time and setting the fixed time to a value that takes into account the difference between the reading speed and the paper feed speed, the optimum paper feed timing can be set to prevent jamming. Can do.

  As described above, when the preceding document D1 is being read and transported after reading, the document D1 is started by feeding the next document D2 before the trailing edge of the document D1 passes through the registration roller 24a. The time interval from the feeding of one document to the feeding of the next document D2 can be shortened. Even if the image formation of the MFP 1 is fast, appropriate paper feeding can be performed without delay.

  Further, since the pickup roller 22 and the paper feed roller 23a are driven by the forward rotation operation of the paper feed motor 50, and the registration roller 24a is driven by the reverse rotation operation of the same paper feed motor 50, the number of driving motors is increased. Can be reduced. Thereby, cost can be reduced.

  The above embodiment is presented as an example, and is not intended to limit the scope of the invention. The novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... MFP, 2 ... Automatic document conveying apparatus, 3 ... Operation panel, 4 ... Paper feed cassette, 5 ... Original plate, 6 ... Original reading part, 20 ... CPU, 21 ... Paper feed tray, 22 ... Pickup roller, 23a ... Paper feeding roller, 24a ... registration roller, 25a ... intermediate transport roller, 26a ... pre-reading roller, 27a ... post-reading roller, 28a ... discharge roller, 29 ... discharge tray, 41 ... empty sensor, 42 ... length sensor, 43 ... Registration sensor 44 ... Pre-reading sensor 50 ... Feeding motor 53 ... First one-way clutch 54 ... Second first one-way clutch 60 ... Read motor

Claims (5)

A paper feed tray on which documents are placed;
A paper feed means for feeding the originals placed on the paper feed tray one by one;
A registration roller for feeding a document fed by the sheet feeding unit to a position in front of the document reading unit;
Conveying means for discharging the document that has reached a position in front of the document reading unit through the document reading unit;
Control means for starting the feeding of the next document by the paper feeding means before the trailing edge of the document being conveyed by the conveying means passes through the registration rollers;
An automatic document feeder characterized by comprising: The paper feeding means is
A pickup roller for picking up the documents placed on the paper feed tray one by one;
A paper feed roller for conveying a document picked up by the pickup roller toward the registration roller;
A paper feed motor for driving these pickup roller and paper feed roller;
including,
The automatic document feeder according to claim 1. The paper feeding means is
A first one-way clutch that transmits power during forward rotation of the paper feed motor to the pickup roller and the paper feed roller and does not transmit power during reverse rotation of the paper feed motor to the pickup roller and the paper feed roller;
A second one-way clutch that transmits power when the paper feed motor is reversed to the registration roller, and does not transmit power when the paper feed motor is reversed to the registration roller;
Further including
The automatic document feeder according to claim 2. The conveying means is
A pre-reading roller that conveys a document that has reached a position in front of the document reading unit toward the document reading unit;
A post-reading roller that conveys the document that has passed through the document reading unit toward the discharge unit;
A read motor for driving these pre-reading roller and post-reading roller;
including,
The automatic document feeder according to any one of claims 1 to 3, wherein A length sensor for detecting the length of the conveyed document at a position before the registration roller;
A registration sensor for detecting whether a document fed from the sheet feeding means has reached a position in front of the registration roller;
A pre-reading sensor for detecting whether the leading edge of the document conveyed by the registration roller has reached a position in front of the document reading unit;
Further comprising
The control unit is configured to supply the sheet feeding unit when document detection by the length sensor changes from on to off, or when the document reading unit starts reading, or when a certain time elapses from any one of these timings. Starts feeding the next document using
The automatic document feeder according to any one of claims 1 to 4, wherein the automatic document feeder is provided.

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