JP3117574B2 - Automatic document feeder and image forming apparatus for juxtaposed documents - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder in which originals are arranged side by side and an image forming apparatus having the same. More specifically, for example, originals stacked on a platen are separated and fed. An automatic document feeder (ADF) for arranging a plurality of (normally two) documents on an image reading unit (platen);
The present invention relates to an image forming apparatus that includes a DF, reads this document, and forms an image on one copy sheet. Note that the document side-by-side includes a document that is arranged and read on a platen, a document that is read while passing two consecutive sheets through a reading position, and the like.

[0002]

2. Description of the Related Art In an automatic document feeder provided in an image forming apparatus such as a copying machine or the like, an image reading unit of the image forming apparatus simultaneously reads images of two originals. Continuous feeding control (hereinafter referred to as 2i) in which the stacked originals are fed to the image reading unit of the image forming apparatus two sheets at a time in a continuous state.
n1 control).

In this 2-in-1 control, Japanese Patent Application Laid-Open No. 3-174
As shown by reference numeral 553, the trailing edge of the preceding document and the trailing edge of the succeeding document are set in the middle of feeding before being set so that the interval between the two documents set in the image reading unit of the image forming apparatus becomes small. A little overlap is made with the tip. Then, the feeding speed of the original by the second feeding means for feeding the preceding original is made faster than the feeding speed of the original by the first feeding means for feeding the succeeding original, and the overlap is made. Is canceled immediately before the following document reaches the second feeding means, and the preceding and following documents are sent to the reading unit by the second feeding means.

[0004]

According to the automatic document feeder described above, if the document interval is set to zero, two documents can be easily set, but the nip operation to the document feeding means is difficult. Inconvenience may occur.

That is, in order to overlap the originals, the preceding original is stopped with the trailing end of the preceding original remaining slightly upstream of the second feeding means, and then the leading end of the succeeding original is left behind. However, in order to prevent a collision between the leading edge and the trailing edge of the document at this time, the trailing edge of the document remaining upstream of the second feeding means is prevented. An escape recess is formed.

Due to the escape recess, when the original is first sent to the feeding means, there is a possibility that the leading end of the original may not be guided well to the feeding means.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic document feeder and an image forming apparatus in which originals are arranged side by side so that an interval between a preceding original and a succeeding original is properly maintained.

[0008]

SUMMARY OF THE INVENTION To solve the above-mentioned problems, the present invention is an automatic document feeder installed in a main body having an image reading section, wherein a first feed rotation for feeding a sheet document is provided. Means, a second feeding rotation means downstream of the first feeding rotation means and further feeding the fed sheet document, the first feeding rotation means, Control means for controlling the movement of the second feeding rotation means, wherein the preceding first sheet document is rotated in a reverse direction by the second feeding rotation means to adjust the amount according to the type of the sheet document. Only to the upstream side, and the subsequent second sheet document
After controlling the first feeding rotation unit to feed the first sheet document until it overlaps the rear end thereof, the first sheet document and the second sheet document are fed simultaneously. When the first sheet document is returned to the upstream side in the automatic document feeder in which the first sheet document is fed faster so that the overlap is cancelled, The automatic document feeder and the main body, wherein a rear end of a first sheet document is displaced from an inside of a guide forming a sheet path connecting the first feeding rotation unit and the second feeding rotation unit. It is characterized in that it leads to a space formed between the apparatus and the apparatus.

Further, the second feeding / rotating means is a conveyance belt arranged on a platen glass on which a sheet original is set.

Further, the second feeding / rotating means can feed the sheet document faster than the first feeding / rotating means, and the overlap is canceled immediately before the leading end of the succeeding sheet document reaches the transport belt. It is characterized by being performed.

[0011]

After the preceding document fed by the first feeding rotation means is further fed to a predetermined position by the second feeding rotation means, the preceding automatic document feeding outside the sheet path on the upstream side is performed. It is returned to the space formed between the device and the main device, and waits. The leading edge of the following document to be fed and the trailing edge of the preceding document are conveyed together in an overlapped state, and the overlap is canceled by changing the feeding speed of both documents, so that a predetermined document interval is set. You.

The amount of return of the preceding document performed to adjust the document interval is controlled by control means so as to change according to the type of document.

Accordingly, the interval between the preceding document and the following document during the continuous feeding control is always constant regardless of the type of the document, and the distance between the preceding document and the following document becomes large.
A state in which the preceding document and the following document overlap does not occur.

As a result, the images of the preceding document and the following document arranged in the image reading section of the image forming apparatus can be correctly read, and no image is lost.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. <Embodiment 1> FIG. 1 shows the overall configuration of an automatic document feeder according to Embodiment 1 of the present invention.

The automatic document feeder 1 is mounted on an upper part of an image forming apparatus (copier) 2 (an upper part of a main body) and separates originals 5 stacked on an original table 3 one by one. The sheet is fed onto a platen glass (image reading unit) 6 installed on the upper part of the image forming apparatus 2.

The originals 5 stacked on the original platen 3 are sent to the separation device 9 in order from the bottom sheet by a half-moon-shaped feeding roller 7 rotating counterclockwise.

The separating device 9 comprises a feed roller 9A rotating in a counterclockwise direction and a retard belt (endless belt) 9B rotating in a counterclockwise direction. When a plurality of originals 5 are sent to the separation device 9, only the lowermost sheet is sent downstream by the feed roller 9A, and the other originals 5 are returned to the original table 3 by the retard belt 9B.

The originals 5 separated one by one by the separating device 9 are sent to the nip portion of the registration roller pair 10 which is not rotating, and the skew is corrected. Thereafter, the document 5 is conveyed to a predetermined position on the platen glass 6 by the registration roller pair 10 and the conveyance belt (endless belt) 11 which start rotating at a predetermined timing.

The image forming operation of the image forming apparatus 2 is performed while the original 5 is set at a predetermined position on the platen glass 6. After the completion of the image forming operation, the original 5 positioned on the platen glass 6 is transported by a conveyor belt 11 rotating counterclockwise and a discharge roller pair 12 rotating in the paper discharge direction.
Is discharged onto a discharge tray (not shown) outside the apparatus.

When the document feeding operation is performed, the stopper 15 for restricting the sliding of the document 5 loaded on the inclined document table 3 is lowered by the stopper solenoid 30 so as to allow the document 5 to slide. I do.

The original 5 that has passed through the registration roller pair 10 in the original feeding operation is guided by the lower guide 16 between the transport belt 11 and the platen glass 6. At this time, the mylar 16a is pushed away. Mylar 16a
Has a rear end fixed to a roller guide, and a front end is free and deflected upward.

Each of the pulleys of the feed roller 7, the feed roller 9A of the separation device 9, and the retard belt 9B of the separation device 9 is driven to rotate by the rotation power of the separation motor 25. The driving roller pulley 11 </ b> A of the registration roller pair 10 and the conveyor belt 11 is driven to rotate by the rotation power of the belt motor 26. The paper discharge roller pair 12 is driven to rotate by the rotational power of the paper discharge motor 27.

The belt motor 26 includes a belt clock interrupter 22 for counting the number of rotations of the belt motor and an electromagnetic brake 29 for applying a braking force to the motor shaft of the belt motor. The paper discharge motor 27 is provided with a paper discharge clock interrupter 23 for counting the number of rotations of the paper discharge motor.

Next, referring to FIG. 2, a document feeding operation in the automatic document feeding apparatus 1 during 2-in-1 control (continuous feeding control) will be described.

First, the first original (previous original) 5A is fed and sent to the nip portion of the registration roller pair 10 that has stopped rotating (the state shown in FIG. 2A).

Next, the first original 5A is fed by the registration roller pair 10 and the transport belt 11 to a position where the rear end 5A2 of the original slightly passes through the nip portion of the registration roller pair 10. Subsequently, the second original (subsequent original) 5B
Is fed to the nip portion of the registration roller pair 10 which stops rotating after the first original 5A is conveyed (the state shown in FIG. 2B).

Next, the first original 5A and the second original 5B are simultaneously transported by the registration roller pair 10 and the transport belt 11, and the trailing end of the first original 5A passes through the lower guide 16. At this point, the conveyance is stopped (the state shown in FIG. 2C).

Next, in this state, the conveyor belt 11 is rotated clockwise (reverse rotation) to return the first original 5A by a fixed amount in the direction of arrow A, and the first original 5A and the second original 5A. 5B
To reduce the interval.

In this case, since the rear end of the first original 5A has passed through the lower guide 16, when the original 5A is returned in the direction of arrow A by the transport belt 11, the mylar 16a
And the rear end of the original enters the lower guide 16.

As described above, when returning the first original 5A by a certain amount, the automatic original feeder 1 changes the value of the return amount X shown in FIG. 3 according to the size (length) of the original 5A. I have.

That is, when the first original 5A and the second original 5B are simultaneously conveyed, it is necessary to prevent the original from buckling due to the pushing of the second original 5B. The transport speed V1 of the transport belt 11 that transports the first document 5A is set slightly higher than the peripheral speed V2 of the registration roller pair 10 that transports the second document 5B (V1> V).
2) Yes.

However, there is a difference in the conveyance speed between the first original 5A and the second original 5B until the second original 5B passes through the nip portion of the registration roller pair 10.
The larger the size (length) of 5B, the greater the effect of the difference in transport speed between the first original 5A and the second original 5B, and the greater the distance between the originals 5A and 5B.

Therefore, in the automatic document feeder 1, a registration sensor (document size detecting means) 17 is provided immediately before (upstream side) the pair of registration rollers 10 to detect a document from the registration sensor 17. 1 based on the signal
The size of the original 5A is measured, and the value of the return amount X is changed according to the measured original size as described above. Thereby, the interval between the originals can be made constant regardless of the length of the sheet.

When the first original 5A is returned by a certain amount in this manner, the registration roller pair 10 and the conveyor belt 11 are again rotated (forward rotation), and the first original 5A and the second original 5A are rotated.
The original 5B is fed to a predetermined position on the platen glass 6. At this time, the first original 5A and the second original 5B are located on the platen glass 6 with a predetermined interval L (state shown in FIG. 2D). The interval L is calculated based on the amount of overlap between the trailing end 5A2 of the original 5A and the leading end 5B1 of the original 5B, the original size, and the difference in feed speed between the belt 11 and the roller 10.

In this state, the image forming operation of the image forming apparatus 2 is performed, and the images of the first original 5A and the second original 5B are simultaneously formed.

When the image forming operation in the image forming apparatus 2 is completed in this way, the first original 5A and the second original 5B are discharged outside the machine by the transport belt 11 and the discharge roller pair 12. The paper is discharged onto the tray.

At the time of this paper ejection, the first original 5A and the second original 5B are detected by a paper ejection sensor 19 installed immediately before (upstream) the paper ejection roller pair 12.

FIG. 4 shows the overall configuration of the control circuit of the automatic document feeder 1.

A CP for controlling the entire automatic document feeder 1
U (one-chip microcomputer with built-in ROM, RAM, etc.) 20, input ports I1 to I5, a document detection sensor 21 for detecting the presence or absence of the document 5 loaded on the document table 3, a document table Document 5 fed from 3
Sensor 17, for detecting the original 5 discharged from above the platen glass 6 to the outside of the machine, a belt clock interrupter 22 provided for the belt motor, and provided for the paper discharge motor. The output clock interrupters 23 are electrically connected to each other.

The output ports O1 to O6 of the CPU 20 are connected to the separation motor 125, the belt motor 26, the paper discharge motor 27, the electromagnetic brake 29 provided on the belt motor 26, the original via the drivers D1 to D6, respectively. Stopper solenoids 30 for driving the stoppers 15 that regulate the sliding of the originals 5 stacked on the table 3 are electrically connected to each other.

The CPU 20 is provided with a non-volatile memory 31 whose memory contents can be rewritten from the outside. The memory 31 stores the value of the return amount X of the first original 5A that differs depending on the original size. That is, corrections for performing return control for each document size are stored.

Next, the control operation of the CPU 20 will be described with reference to FIGS. <Document Feeding in 2-in-1> See FIG. 5 First, the separation process (S1) and the feeding process (S2) of the first document 5A are performed, and the rear end 5A2 of the document A is downstream from the register roller pair 10 by a predetermined distance. Transport until it is located on the side. Subsequently, the separation process (S3) of the second document 5B is performed, and the document 5B is transported to the nip portion of the registration roller pair 10 (the state shown in FIG. 2B). Next, a feeding process (S4) for the first original 5A and the second original 5B is performed, and the originals 5A and 5B are set at the exposure position on the platen glass 6 in a state of being adjacent to each other (FIG. d) condition). Thereafter, when a paper discharge request (S5) is made due to the end of the image forming operation of the image forming apparatus, a paper discharge process (S6) of the originals 5A and 5B is performed to perform 2i.
The document feeding operation at n1 ends. <Document Separation Processing> See FIG. 6 First, it is determined whether or not the separation processing is for the first document 5A (S1). As a result, in the case of the separation process of the first document 5A, the separation motor 25 is turned on (S2), and at the same time, the stopper solenoid 30 is turned on (S3). In the case of the separation process of the second original 5B, the separation motor 25
Only ON is set (S4).

Next, when the registration sensor 17 detects the leading edge of the document (S5), the separation loop timer is started (S6). Then, after the timer set time ends (S7), the separation motor 25 is turned off (S8). As a result, the first original 5A or the second original 5B is
At 0, the operation is stopped in a state where a predetermined amount of loop is formed, and the skew during separation is corrected. <Normal Document Feeding Process> See FIG. 7 First, the registration motor pair 10 and the transport belt 11 are driven, and the belt motor 26 is turned on in a normal rotation so as to feed the document 5 after the separation process (S1). . At the same time, a document size check counter counting by a clock signal input from the belt clock interrupter 22 is started, and measurement of the document size is started (S2).

Next, the rear end of the original 5 is
Is passed (S3), the document size check counter is stopped (S4), and the document size is determined by a document size check subroutine described later based on the count data (S5). At the same time, a stop counter 1 for stopping the original 5 at a predetermined position on the platen glass 6 is started (S6), and after the counter 1 finishes counting (S7), the rotation of the belt motor 26 is turned off (S8). ) And the electromagnetic brake 29 is turned on (S
9) End the paper feeding process. <Feeding Process of First Document in 2-in-1> See FIG. 8 First, in order to drive the registration roller pair 10 and the transport belt 11 to feed the first document 5A after the separation process,
The normal rotation of the belt motor 26 is turned on (S1). At the same time, a document size check counter that counts with a clock signal input from the belt clock interrupter 22 is started to start measuring the document size (S
2).

Next, when the trailing end 5A2 of the first original 5A has passed the registration sensor 17 (S3), the original size check counter is stopped (S4), and based on the count data, an original size check subroutine to be described later is executed. The size of the document is determined in advance (S5). At the same time, the rear end 5A2 of the first original 5A is
The stop counter 2 for stopping the nip portion at a position downstream from the nip portion by a predetermined distance (for example, 29 mm) is started (S
6) After the count of the counter 2 is completed (S7), the rotation of the belt motor 26 is turned off (S8), and the electromagnetic brake 29 is turned on (S9), and the first original is fed in 2in1. The process ends. <Document Size Check Process> See FIG. 9 First, a corrected document size value is calculated by adding the document size check counter data to the distance from the nip position of the registration roller pair 10 to the registration sensor 17 (S
1). At this time, since the document is being conveyed by the registration roller pair 10 and the conveyance belt 11, the feed amount and the count value by the belt clock interrupter 22 surely match.

Next, the calculated document size value is compared with each of the document size data D1 to D7 (S2 to S7) to determine that the document size is A3, B4, A4R, B5.
A size determination is made as to which of R, A4, B5 and A5. <Feeding Processing of First and Second Documents in 2-in-1> See FIG. 10 First, the registration roller pair 10 and the conveyor belt 11 are driven to feed the first document 5A and the second document 5B. The belt motor 26 is turned on in the normal rotation to feed the sheet (S1). At the same time, the stop counter 3 is started to stop the first document 5A and the second document 5B in a state of straddling the lower guide 16 and the platen glass 6 (the state of FIG. 2C) ( S2) After the count of the counter 3 is completed (S3), the rotation of the belt motor 26 is turned off (S2).
4). At the same time, the electromagnetic brake 29 is turned on (S
5).

Next, after a predetermined time elapses (S
6), the electromagnetic brake 29 is turned off (S7), the belt motor 26 is simultaneously turned reversely on (S8), and a return counter for controlling the return of the first original 5A by a predetermined amount is started (S9). After the counting by the counter is completed (S10), the rotation of the belt motor 26 is turned off again (S11), and at the same time, the electromagnetic brake 29 is turned on (S12).

Next, after a predetermined time has elapsed (S
13) The electromagnetic brake 29 is turned off (S14), and the belt motor 26 is turned on for normal rotation (S15). A stop counter 1 for simultaneously stopping the first and second originals 5A and 5B at predetermined positions on the platen glass 6.
Is started (S16), and after the counting of the counter 1 is completed (S17), the rotation of the belt motor 26 is turned off (S18) and the electromagnetic brake 29 is turned on (S16).
19) The feeding process of the first and second originals in 2in1 is ended.

In this process, since the return counter value must be variable depending on the document size, the default value of the return counter value for each size is burned in advance in the ROM, and the correction value by the machine or environment is further stored. By adding (adding) to the default value, more accurate sheet interval control is possible.

The correction value is stored in a non-volatile memory 31 in the CPU 20 and can be rewritten from outside the CPU 20. <Original Document Discharge Processing> See FIG. 11 First, the time when the paper output sensor 19 detects the leading edge of the original (S1), and at the same time as detecting the leading edge of the original, the discharging roller pair
2 is driven to rotate the discharge motor 27 (S
2). Next, the detection of the trailing end of the document by the paper discharge sensor 19 is performed (S3).

When the trailing edge of the document is detected,
The discharge counter 1 corresponding to a distance of 10 mm from the nip center of the discharge roller pair 12 is started from 9 (S4).
The sheet discharge speed is set to be low until the counting of the sheet discharge counter 1 is completed (S5). When the count of the discharge counter 1 ends (S6), the discharge motor 2
7 is turned off (S7), and the paper discharge process ends.

At the time of this sheet discharge processing, the count amount by the sheet discharge counter (= discharge clock interrupter 23) and the feed amount by the sheet discharge roller pair 12 surely coincide with each other. (Return counter set SUB) ... FIG.

The return counter setting subroutine will be described.

In this return counter setting subroutine, the value of C
The “return amount” for each document size is called by referring to the size data held in the RAM in the PU, and the “return amount correction value” for each device stored in the nonvolatile memory (EEPROM) is obtained. Correction is performed by calculating the return amount for each size, and the corrected return amount for each document size is converted into the movement amount of the transport belt 10 driven by the belt motor 26 and set as a return counter. The calculation formula in that case is shown below. [Return counter] = [correction storage value for each device] × [Default value of return counter for A5] ÷ [Return counter for detected document size] <Second Embodiment> In the first embodiment, the nonvolatile counter is used. Only one type of correction storage value is stored in the rewritable memory element of the gender, and in (return counter set SUB), the arithmetic correction for each document size is performed according to the length of the document in the feed direction. In the embodiment, if the capacity of the non-volatile rewritable memory has a margin, a plurality of correction values for each document size can be stored and corrected.

The above (return counter set SUB) in the case of the second embodiment is as follows. (Return counter set SUB) ... FIG.

The return counter setting subroutine in the second embodiment will be described.

In this return counter setting subroutine, the value of C
The “return amount” for each document size is called by referring to the size data held in the RAM in the PU, and the “return amount” for each device and document size stored in the non-volatile memory (EEPROM) is referred to. The correction value is called and corrected, and the corrected return amount for each document size is converted into the movement amount of the transport belt 10 by driving the belt motor BELTTMTR and set as a return counter. The calculation formula in that case is shown below. [Return counter] = [correction storage value for each device] + [correction storage value for each document size] <Third Embodiment> In the second embodiment, a nonvolatile rewritable memory element (such as an EEPROM) is used. Although it is used as a storage unit for the correction value at the time of the sheet return control, in the third embodiment, other values are used.
The analog VR is converted to the A
After connecting to the / D conversion function port and A / D converting the set value of the analog VR, the data can be used as a correction value at the time of sheet return control.

FIG. 14 is a block diagram showing a circuit configuration of the third embodiment.

FIG. 14 is a block diagram showing a circuit configuration of a control device of the automatic document feeder of the third embodiment.

The control circuit is mainly composed of a one-chip microcomputer (E1) 40 having a built-in ROM, RAM, etc., and has input ports I1 to I5 of the microcomputer E1.
Are input with signals from various sensors. The output ports O1 to O6 of the microcomputer E1 are connected to drivers D1 to D6, respectively.
Each load is connected to the load 6 via a corresponding one of the loads. Separation motors (SR) for driving the separation roller 6 and the separation conveyance roller 7, respectively
MTR), a registration roller 9, a belt motor (BELTMTR) 30 for driving the conveyor belt 10, and a belt clock interrupter (BPI) for counting the number of rotations of the belt motor (= the number of rotations of the registration roller 9 and the conveyor belt 10). 31, an electromagnetic brake (BK) 32 for stopping the drive shaft of the belt motor, and a stopper drive solenoid (ST) for driving a document stopper (not shown)
PSL) 33, a discharge motor (EJCTMTR) 35 for driving the discharge roller 13, and a discharge clock interrupter (EPI) for counting the number of rotations of the discharge motor (= the number of rotations of the discharge roller 13). 36, a document detection sensor 37 for detecting that a document is placed on the sheet stacking table 3, a registration sensor 15 (S1) disposed upstream of the registration roller 9, and a registration sensor 15 (S1) disposed upstream of the discharge roller 13. The paper ejection sensor (S2) 39.

A non-volatile memory element (EEPROM) for storing a correction value and the like for correcting a return control for each original size, which will be described later, is arranged in the control device EI. Is configured so that the contents of the memory can be rewritten. Fourth Embodiment Next, a fourth embodiment will be described with reference to FIGS. Since the configuration and the flowchart of the apparatus shown in the first embodiment of the first invention are the same as those of the present invention,
Its illustration and description are omitted. (2nd1 First Document Feeding Process) FIG. 15 The 2nd1 first document feeding process will be described.

Feed processing of the first original at 2 in 1 (2 in 1)
1_1entsq), the belt motor 2 is driven to drive the registration roller pair 10 and the transport belt 11 to transport the document from the sheet path SP1 to the sheet path SP2.
At the same time as the normal rotation of 6 (ent 1), a size check counter counting by a clock signal input from the belt clock interrupter 22 is started, and the measurement of the document size is started (ent 2). Then, the original is conveyed, and the trailing end of the original has passed the registration sensor S1 (en
At the same time as t3), the size check counter is stopped (ent4), and the document size is determined by the size check subroutine based on the data (ent5).
In (ent 3), the maximum document transport length determined in advance in real time is compared with the document size length (ent 6). If the document size length is longer than the maximum document transport length, ent 10 And the subsequent document conveyance is immediately stopped by the work continuation prevention means. If a negative determination is made in ent 6, the processing is continued as it is, and the stop counter 1 for stopping the document at a predetermined position (20 mm in this embodiment) downstream from the nip center of the registration roller pair 10 is set. After the start (ent 7) and the end of the counter 1 (ent 8), the drive of the belt motor 26 is turned off, and the drive of the electromagnetic brake 29 is turned on at the same time (ent 9). Is completed. (Feeding process of the 1-2 sheet at 2 in 1)... The feeding process of the 1-2 sheet at 2 in 1 will be described.

2in11-2nd sheet feeding process (2in1_1-
2entsq), the registration roller pair 9 and the conveyance belt 10 are driven to move the original to the sheet paths SP1 and SP2.
, The belt motor 26 is turned on in the normal direction so as to be conveyed to the sheet path SP3, and at the same time, a size check counter for detecting the document size is started (ent
1) A stop counter 3 is started (ent 2) in order to stop in a state where two originals are straddled over the sheet paths SP2 and SP3 (FIG. 2C), and after the counter 3 ends ( ent 3), the drive of the belt motor 26 is turned off, and at the same time, the drive of the electromagnetic brake BK is turned on (ent 4). Further, after a predetermined time has elapsed (ent 5), the electromagnetic brake 2
9 is turned off, and the belt motor 26 is turned on in the reverse direction (ent 6).
At the same time, a return counter setting for controlling the return of the first document by a predetermined amount is called and the return counter is started (ent 7), and after the end of the counter (ent 8), the drive of the belt motor BELTMTR is turned off again. At the same time, the drive of the electromagnetic brake BK is turned on (ent 9). Further, after a lapse of a predetermined time (ent 10), the electromagnetic brake 29 is turned off, the belt motor 26 is normally rotated on (ent 11), and the registration sensor S1 detects the rear end of the document (en 10).
At t12), the size check counter is stopped, and the document size is determined in the size check subroutine (ent13). At (ent 12), the maximum original transport length determined in advance in real time is compared with [determined original size length + previous original size length + inter-sheet size] (ent
14) If the document size length is longer than the maximum document transport length, control is transferred to ent 18 and the subsequent document transport is immediately stopped by the work continuation prevention means. en
If a negative determination is made at t14, the stop counter 1 for stopping the first and second originals at a predetermined position on the platen glass 16 is started at the same time (ent 15), and the counter 1 ends. After that (ent 16), the drive of the belt motor 26 is turned off and the drive of the electromagnetic brake 29 is turned on at the same time (ent 17), thereby completing the 2 in 11th sheet feeding process.

At this time, since the value of the return counter needs to be variable depending on the document size, as described above, the default value of the return counter value for each size is previously printed on the ROM, and By calculating a correction value based on the size of the original in the paper feeding direction and the default value, it is possible to perform highly accurate paper interval control.

The correction value is stored in a non-volatile writable memory on the control device, and is configured to be externally rewritable. (Return counter set SUB) ... FIG.

The return counter setting subroutine will be described.

In this return counter setting subroutine, the value of C
The return amount for each document size is called by referring to the size data held in the RAM in the PU, and the return amount correction value for each device stored in the nonvolatile memory (EEPROM) is returned for each size. The amount is corrected by calculating the amount, and the corrected amount of return for each document size is converted into the amount of movement of the transport belt 10 driven by the belt motor 26 and set as a return counter. Fifth Embodiment FIG. 18 shows the entire configuration of an automatic document feeder according to a fifth embodiment of the present invention.

In the automatic document feeder 1 of the present embodiment, taking into account that the document transport time by the registration roller pair 10 and the like changes when the thickness of the document 5 differs, the automatic document feeder 1 of the first embodiment described above. The feeding device 1 is further provided with a unit for detecting the thickness of the original 5, and the first original 5 </ b> A
Is set according to the size of the document 5 and the thickness of the document 5.

Here, as means for detecting the thickness of the document 5, a displacement detection sensor 32 for detecting the displacement of the movable roller 10A of the pair of registration rollers 10 is provided, and the displacement from the displacement detection sensor 32 is set. The thickness of the first original 5A is measured based on the amount information.

The movable roller 10A of the pair of registration rollers 10 is urged by a pressure spring (leaf spring) 33 against the fixed roller 10B at a predetermined pressure.

Next, FIGS. 19 to 22 show the flow of sheet materials when a plurality of sheet materials are continuously fed using the automatic sheet material feeding device and the sheet materials are simultaneously image-formed.
This will be described with reference to FIG.

First, the plurality of sheets 5 placed on the sheet loading table 5 are sent to the separating section 9 by the half-moon roller 7 and separated one by one from the lowermost part. Then, it reaches the pair of registration rollers 10 and temporarily stops at the nip (see FIG. 2A).

Assuming that the first sheet material of the above-mentioned sheet material is 5A, the sheet material 5A is fed in the direction to the conveying section 11 by the registration roller pair 10. Then, when the trailing end slightly advances from the nip portion of the registration roller pair 10, it stops again. Next, the second sheet material 5B is separated and fed by the separation unit 9 in the same manner as the above operation, and stops once it comes into contact with the nip portion of the registration roller pair 10 (see FIG. 19). At this time, the distance between the tip of the trailing edge and the sheet material 5B of the sheet material 5A and L _1.

Then, the sheet material 5A and the sheet material 5
When the rear end of the first sheet material 5A passes through the lower guide 16, the conveyance of the sheet material is stopped again. (See FIG. 20). At this time, assuming that the sheet conveying speed of the registration roller pair 10 is V ₁ and the sheet conveying speed of the conveying belt 11 is V ₂ , the sheet members 5A, 5B
When the sheet material 5A is conveyed from the state shown in FIG. 19 to the state shown in FIG.
Is sandwiched are transported at the transportation speed of V _1, the sheet material 5A
There is conveyed at the conveying speed of V ₂ by the conveyor belt 11.
If the distance corresponding to the transport length of the sheet material by the speed difference between .DELTA.1 _1, distance L ₂ between the tip of the trailing edge and the sheet material 5B of the sheet material 5A state as shown in FIG. 20 is L ₁ +
Δ1 ₁ to become. Further, as shown in FIG. 22, when the sheet materials 5A and 5B are conveyed until the leading end of the sheet material 5B reaches the nip portion of the conveyance unit 11, the separation corresponding to the conveyance length of the sheet material due to the speed difference at this time. distance as .DELTA.1 _2, distance L ₃ between the sheet G ₁ and the sheet material G ₂ on the platen glass 6 becomes L ₂ + _{Δ1 2.}

In the ordinary two-in-one mode, L ₃ = 0
Therefore, in the present apparatus, the sheet material 5A,
5B interval adjustment is performed. That is, by the conveying belt 11 from the state as shown in FIG. 20 is only the reverse rotation amount corresponding to the distance L ₃ for transporting the sheet material 5A in the opposite direction (see FIG. 21). The distance between the sheet material 5A and the sheet material 5B is adjusted by adjusting the amount of conveyance in the opposite direction at this time. The user can arbitrarily set the amount of conveyance in the reverse direction using external input means.

When the conveyance in the reverse direction is completed, the first sheet material 5A and the second sheet material 5B are both placed on the platen glass 6 which is a predetermined image reading area by the registration roller pair 10 and the conveyance belt 11. And the information is read. After the reading is completed, the sheet materials 5A, 5B
Is discharged from the platen glass 6 by the conveyor belt 11 and discharged onto the discharge table 5a outside the apparatus by the discharge roller 12.

In this apparatus, as described above, the amount of the first sheet material 5A in the state shown in FIG.
The gap with B is adjusted.

The following describes how the first sheet material 5A is retracted in order to set the interval to "zero". In this apparatus, as described above, the transport speed of the registration roller pair 10 is V ₁ , the transport speed of the transport belt 11 is V _2, and the relationship between the transport speeds is V ₁ <V ₂ . Further, the sheet material 5A in the state shown in FIG.
To the spacing between the tip of the trailing edge and the sheet material 5B and L _1.

[0080] In FIG. 20, a pair of registration rollers 10 by a distance which is conveying the sheet 5B, i.e., when the distance from the nip portion of the registration roller pair 10 to the tip of the sheet material 5B and L _4, the time required for the conveying t is t = L ₄ / V ₁ (1) The distance to convey the sheet material 5A by the conveyor belt 11, i.e. the distance from the nip portion of the registration roller pair 10 from the point of the distance L ₁ to the rear end of the sheet material 5A L
When _5, the distance L _{5 represents, L 5 = V 2 · t} = V 2 · (L 4 / V 1) becomes ... (2). Accordingly, the distance from the nip portion of the registration roller pair 10 until the trailing edge of the sheet material 5A becomes L ₁ + L _5.

Therefore, the distance L ₂ between the rear end of the sheet material 5A and the front end of the sheet material 5B in FIG. 20 is L ₂ = (L ₁ + L ₅ ) −L ₄ = ｛L ₁ + V ₂ · (L ₄ / V ₁ )｝ − L ₄ (3)

When the sheet is conveyed again in the state as shown in FIG. 20, the distance until the leading end of the sheet 5B reaches the nip portion of the conveying belt 11 is equal to the distance L _{2 as shown} in FIG. Therefore, if the time required for the conveyance is T, T = L ₂ / V ₁ (4) In this case, if the conveyance distance of the sheet material 5A that is conveyed by time T by the conveyor belt 11, _{L 3, L = V 2 ·} T = V 2 · (L 2 / V 1) becomes ...... (5). The distance L ₃ corresponds to the distance between the tip of the trailing edge and the sheet material 5B of the sheet material 5A that is maintained on the platen glass 6 (interval).

Therefore, the rear end of the sheet material 5A is set at the distance L
If it is retracted by _three , the distance L between the rear end of the sheet material 5A maintained on the platen glass 6 and the front end of the sheet material 5B
₃ becomes "zero".

Accordingly, the interval L ₃ is given by the following equation (5): L ₃ = {L ₁ + (V ₂ / V ₁ ) · L ₄ −L ₄ } · V ₂ / V ₁ / ... (6) Become. Therefore, the conveying speed V ₁ of the registration roller pair 10,
Once the transport speed V ₂ and the distances L ₁ and L ₄ of the transport unit 11 are determined, the distance L _{3 that} is the amount of transport in the reverse direction can be obtained. The distances L ₁ and L ₄ are determined by a count timer.

[0085] Thus, depending on the sheet size, it varies the time to be bound by the registration roller 10, in consideration of the duty time by the sheet size, L ₃
To adjust. Since the long restraint time longer sheet, a longer L _3.

[0086]

According to the present invention, the trailing end is guided to the space formed between the automatic document feeder and the main body, which is outside the guide for returning the preceding document and forming the sheet path, and remains. Therefore, a relief portion at the rear end can be provided in a portion that does not adversely affect the feeding path of the following document. In order to change the return amount according to the type of sheet document and to support various types of sheets, it is necessary to provide a sufficiently large path for the trailing end of the sheet to return. As described above, according to the present invention, a sufficient return space is secured by guiding the sheet path from the inside of the guide forming the sheet path to the space formed between the automatic document feeder and the main body. It can handle various types of seats.

Further, since the return amount of the preceding document is changed to a value corresponding to the type of the document based on the document type information, the interval between the preceding document and the following document is always constant regardless of the type of the document. There is no increase in the interval between the line documents, and no overlap between the preceding document and the subsequent document.

Therefore, the images of the preceding document and the following document are correctly read by the image reading section of the image forming apparatus, and the image is not lost. In addition, the document is not damaged due to contact between the documents.

[Brief description of the drawings]

FIG. 1 is a vertical side view showing the entire configuration of an automatic document feeder according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view for explaining the operation of the automatic document feeder at the time of 2 in 1 control.

FIG. 3 is an enlarged vertical cross-sectional side view of a main part for explaining a returning operation of a preceding original at the time of 2 in 1 control in the automatic original feeding apparatus.

FIG. 4 is a block diagram showing an overall configuration of a control circuit in the automatic document feeder.

FIG. 5 is a diagram showing a <2in> of a CPU in the automatic document feeder.
1 is a flowchart illustrating an operation of “1 original feeding”.

FIG. 6 is a flowchart showing a <document separation process> operation of the CPU.

FIG. 7 is a flowchart showing a <normal document feeding process> operation of the CPU.

FIG. 8 is a flowchart showing a <2nd in 1st original document feeding process> operation of the CPU.

FIG. 9 is a flowchart showing a <document size check process> operation of the CPU.

FIG. 10 is a flowchart showing the operation of the first CPU and the second original feeding process in 2in1 by the CPU;

FIG. 11 is a flowchart showing a <document discharging process> operation of the CPU.

FIG. 12 is a flowchart of a return counter setting routine.

FIG. 13 is a flowchart of a second example of the return counter setting routine.

FIG. 14 is a block diagram of an automatic document feeder according to a third embodiment.

FIG. 15 is a flowchart illustrating a process of feeding a first original in 2in1 according to the fourth embodiment.

FIG. 16 is a flowchart of a process of feeding the first to second originals in the 2in1 mode.

FIG. 17 is a flowchart of a return counter setting routine.

FIG. 18 is a vertical sectional side view showing the entire configuration of an automatic document feeder according to a fifth embodiment of the present invention.

FIG. 19 is a detailed operation explanatory view of FIG. 2 (FIG. 2 (b)).

FIG. 20 is a detailed operation explanatory view of FIG. 2 (FIG. 2 (c)).

FIG. 21 is a detailed operation explanatory diagram of FIG. 2;

FIG. 22 is a detailed operation explanatory diagram of FIG. 2;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 automatic document feeder 2 image forming device 5 sheet document 5A preceding sheet document 5B trailing sheet document 6 platen glass (image reading unit) 10 registration roller pair (first feeding rotation unit) 11 transport belt (second Feeding rotation means) 16 lower guide (retreat means) 17 registration sensor (document size detection means) 20 CPU (control means) 26 belt motor 32 displacement amount detection sensor (document thickness detection means)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-174553 (JP, A) JP-A-1-294130 (JP, A) JP-A-4-32859 (JP, A) JP-A-4-32859 338982 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 107 G03B 27/58-27/64 B65H 9/00-9/20 B65H 29/54-29 / 70

Claims (4)

(57) [Claims] 1. An automatic document feeder installed in a main body device having an image reading unit, comprising: a first feeding rotation unit for feeding a sheet document; and a downstream of the first feeding rotation unit. A second feeding rotation means for further feeding the fed sheet original, and a control for controlling movements of the first feeding rotation means and the second feeding rotation means. Means for returning the preceding first sheet document to the upstream side by an amount corresponding to the type of the sheet document by rotating the second feeding rotation means in the reverse direction, and After controlling the first feeding rotation unit to feed the document until it overlaps the rear end of the first sheet document, the first sheet document and the second sheet document are simultaneously So that the overlap is canceled when feeding In the automatic document feeder, in which the first sheet document is fed faster, the rear end of the first sheet document is moved to the first position when returning the first sheet document to the upstream side. Feeding rotation means and the second
Wherein the guide is guided to a space formed between the automatic document feeder and the main body device, which is outside the guide for forming a sheet path connecting the feeding rotation means. Feeding device. 2. The automatic document feeder according to claim 1, wherein the second feeding rotation unit is a transport belt disposed on a platen glass on which a sheet document is set. 3. The second feeding / rotating means can feed the sheet document faster than the first feeding / rotating means, and the overlap is canceled immediately before the leading edge of the following sheet document reaches the transport belt. 3. The automatic document feeder according to claim 2, wherein the document is arranged side by side. 4. The automatic document feeder according to claim 1, further comprising: an image reading unit that copies images of two originals arranged inside the main body unit and arranged in the image reading unit on one sheet. An image forming apparatus, comprising: an image forming unit.