JP2998104B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a circulating automatic document feeder for automatically feeding large and small size documents, an image forming means for forming an image by scanning with an optical system, The present invention relates to an image forming apparatus having a re-sending function of re-feeding a transfer sheet transferred on one side to transfer the original to both sides of a fed transfer sheet.

[Conventional technology]

Conventionally, a recirculating automatic document feeder (RDH)
Originals of different sizes such as A3 size and A3 size are mixed, and these originals are automatically fed, so that the first original is transferred to one side (first side) of the transfer paper. 2. Description of the Related Art There is known a single-sided original-double-sided copying machine (image forming apparatus) configured to transfer an original to the other side (second side) of the transfer paper.

In such an image forming apparatus, a transfer sheet suitable for the larger document size is automatically selected from the first and second documents (JP-A-63-309976) or by using the operation unit. When the first document is A4 size and the second document is A3 size, the transfer paper is set to A3 size.

On the other hand, because of the configuration of the apparatus, the transfer direction of the transfer paper when the image is transferred to the first surface and the transfer surface to the second surface of the transfer paper are opposite to each other. If the original is A3 size, the A4 size original is transferred to the first half of the transfer paper in the transport direction (left side in FIG. 6 (a)). When the original is A3 size and the second original is A4 size, the A4 size original is transferred to the first half of the transfer sheet in the transport direction (the right side in FIG. 6B).

Further, the image forming apparatus is provided with a paper folding unit for folding the A3 size transfer paper into the A4 size, so that the transferred transfer paper is folded in a Z-shape.

[Problems to be solved by the invention]

However, in the case of Z-folding with leading edge binding to the leading end side in the transfer paper transport direction at the time of forming the first surface image, the first half in the transfer paper transport direction at the time of forming the second screen image is folded in half and overlapped with the latter half. Therefore, when the first document is A3 size and the second document is A4 size as shown in FIG. 6B, the A4 size document portion is folded into a Z-shape, and the A4 size document is folded. Is difficult to read.

Similarly, in the case of Z-folding with rear-end binding that binds to the rear end side of the transfer paper conveyance direction during the first-side image formation, the first half in the transfer paper conveyance direction during the first-side image formation is folded in half, and When the first document is A4 size and the second document is A3 size as shown in FIG. 6 (a), the A4 size document portion is folded in a Z-shape. , A4 size originals are hard to see.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in order to prevent a transfer image corresponding to a small size document from being folded when originals of different sizes are transferred to both sides of a transfer sheet. The purpose of the present invention is to provide an image forming apparatus which facilitates reading of a document by appropriately switching the transfer position of the image forming apparatus, and improves the appearance.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a circulating automatic document feeder for automatically feeding large and small size documents, image forming means for forming an image by scanning with an optical system, and feeding the document. To transfer to the first and second sides of transfer paper
An image forming apparatus having a resending function of conveying the transfer paper transferred to the surface in the reverse direction with the rear end in the transfer paper conveyance direction at the time of forming the first surface image and re-feeding the paper to the image forming means; Preliminary feeding means for pre-feeding the originals, detecting means for detecting the size of each original at the time of the preliminary feeding, storage means for storing the detected original sizes, and Transfer sheet selecting means for selecting to feed a transfer sheet of a size corresponding to image formation of a large-size document among large-size documents, and leading-edge binding or binding at the leading end side in the transfer paper transport direction at the time of first-side image formation It is possible to perform rear-end binding that binds to the rear end side in the transfer paper transport direction at the time of the first-side image formation. Or, the original to be bound on the front end and transferred to both sides of the transfer paper In order to transfer the small-size document to the rear half of the transfer paper in the transfer paper transport direction in the case of the large-size and small-size orders, the optical system is configured to control the paper feeding timing to the forming means when transferring the small-size document. And timing control means for making the scanning relatively earlier than the scanning start.

[Action]

According to the image forming apparatus having the above configuration, the original placed on the circulating automatic original feeder is pre-fed, the original size of each original is detected at the time of the preliminary feeding, and the detected original size is stored. Then, among the original sizes of the originals to be transferred onto both sides of the transfer paper, a transfer paper having a size corresponding to image formation of a large-size original is selected and fed. When the originals to be transferred on both sides of the rear end binding (hereinafter referred to as right binding) and on both sides of the transfer paper are in the order of small size and large size, the paper feeding timing to the image forming means at the time of transferring the small size original is optical. The small-sized document is transferred to the second half of one side of the transfer sheet relatively early with respect to the start of scanning of the system, and the large-size document is transferred to the other side of the selected transfer sheet. The sheet is fed again to the image forming means.

On the other hand, if the originals to be transferred to both sides of the transfer paper are in the order of large size and small size, the large size original is transferred to one side of the transfer paper, and the small size When the original is transferred, the paper feed timing to the image forming means is advanced relatively to the start of scanning of the optical system, and the small-size original is transferred to the rear half of the other side of the selected transfer paper. .

〔Example〕

FIG. 2 is a schematic configuration diagram showing an example of the image forming apparatus according to the present invention.

The image forming apparatus has a contact glass 20 and a recirculating automatic document feeder (RDH) 21 on its upper surface, an optical system L, an image forming means P, and a re-feeding mechanism Q inside. A paper folding unit R and a staple unit S are provided. Then, when the operation unit (not shown) sets the double-sided copy mode, originals of different sizes such as A4 size and A3 size mixedly loaded on the RDH 21 are sequentially transferred to both sides of the transfer paper, and thereafter, the paper is folded. The unit R is configured to be folded into a Z-shape (hereinafter, referred to as a Z-fold).

The RDH 21 includes a document table 211, a paper feed roller 212, a registration roller 213, a conveyance belt 214, a conveyance roller 215, and a discharge roller 2.
16, 218, a discharge guide unit 217, a document size sensor 219, and the like. When the number of originals and the original size of each original are detected by preliminarily circulating a plurality of originals mixed in the original 211 and detecting the number of originals and the original size of each original, one sheet from the lowest original is fed by the feed roller 212 and the registration roller 213. The number of documents and the size of each document are detected and stored by a document size sensor 219 described later. Thereafter, the document is again placed on the document table 211 via the discharge guide 217 by the transport belt 214 and the discharge rollers 216 and 218.
When the original is to be transferred onto a transfer sheet, the original is transported one by one from the lowermost original, sent out onto the contact glass 20, and stopped at a predetermined position on the contact glass 20 by the transport belt 214. After this, the original is transported
The document is again placed on the document table 211 by the discharge rollers 214 and 218.

The document size sensor 219 is composed of, for example, a plurality of photo sensors, detects the number and size of each document sent from the document 211, and outputs the detection signal to the control system. That is, the document size sensor 219
For example, a photo sensor is arranged side by side in the width direction of a document path, the width of the document is detected based on the state of the photo sensor that detects the document, and the number and size of the document are detected based on the detection time of the passing document. The document size is detected based on these widths and dimensions.

The optical system L includes a light source including a halogen lamp 22 and a reflecting plate 23, reflecting mirrors 24, 25, 26, a lens unit 27, and fixed mirrors 28, 2.
Consists of 9,30. Then, the original set on the RDH 21 is supplied toward the contact glass 20, and is stopped at a predetermined position on the contact glass 20 to start the transfer operation. After the reflected light is guided to the lens unit 27 through the reflecting mirrors 24 to 26, the photosensitive drum 31 described below is exposed through the fixed mirrors 28 to 30.

The image forming means P includes a photosensitive drum 31, a charging device 32, a blank lamp 33, developing devices 34 and 35 for multicolor copying,
A transfer device 36, a separation device 37, a cleaning device 38 and the like are provided. After the surface of the photosensitive drum 31 is uniformly charged by the charging device 32, the surface is exposed by the reflector to form an electrostatic latent image. The electrostatic latent image is developed with toner by the developing device 34 or the developing device 35, and thereafter, the transfer device 36
Is transferred to the transfer paper by the separation unit 37, and is separated from the photosensitive drum 31 by the separation device 37. Further, as a sheet feeding mechanism, sheet feeding cassettes 39 and 40 and sheet feeding rollers 41 and 42 are arranged in order from the upstream in the feeding direction.
A pair of registration rollers 43 and 44 are provided, and transfer paper is fed to the photosensitive drum 31 by these paper feed mechanisms, and transfer is performed. Further, the cleaning device 38 cleans the toner remaining on the surface of the photosensitive drum 31 after the transfer. A transport belt 45, a fixing device 46, a discharge roller 47, and the like are disposed downstream in the transport direction of the transfer paper after the transfer. Then, the transfer paper after the transfer to one side is fixed to the fixing device 46.
Is conveyed to the re-feeding mechanism Q in order to perform transfer to the other surface.

The resending mechanism Q includes a switching guide 48 to the resending side, a switching guide 49 for double-sided switching, a reversing guide section 50, a reversing belt 51 for switchback, a switchback guide section 52, an intermediate tray section 53, and a frontward roller 54. , A forward belt 55, a re-feed roller 56, and the like. When the mode is set to the two-sided copy mode, the original is first transferred onto one side, and the switching guide 4
The transfer paper conveyed to the re-sending mechanism Q via 8,49 is a reversing belt
It is once conveyed to the switchback guide section 52 by 51.
Thereafter, the transfer paper is inverted and conveyed to the intermediate tray 53 through the inversion guide 50 by the inversion drive of the inversion belt 51, and is temporarily stocked.

Then, the contact glass 20 of the next original is
When the automatic supply to the upper side is started, the transfer paper is conveyed to the registration roller pair 44 by the front-advancing roller 54, the front-advancing belt 55, and the re-feed roller 56, and is brought into a standby state. Is fed to the photosensitive drum 31 with the top facing up. Then, when the original is transferred to the other surface, the transfer paper is fixed by the fixing device 46 and then conveyed to the paper folding unit R via the discharge roller 47.

The paper folding unit R includes a transport roller 57, a switching guide 58 to the paper folding side, a transport guide section 59, a stopper section 60, a paper folding section 61, a discharge guide section 62, a transport roller pair 63, and the like. Then, the transfer paper conveyed via the discharge roller 47 is conveyed to the stopper 60 via the switching guide 58 and the conveyance guide 59 and is temporarily held. Next, the transfer paper is Z-folded by the paper folding section 61 at the leading end of the first surface in the carrying direction (corresponding to the trailing end of the second surface in the carrying direction) by left binding. The sheet is conveyed to the staple unit S through the roller pair 63.

The staple unit S includes a switching guide 64, a discharge roller unit 65, a shift tray 66, a paper alignment mechanism 67, and a stapler 68.
And a staple tray 69 and the like. The transfer guide transported via the transport rollers 63 is switched by the switching guide 64 between being discharged to the shift tray 66 and transported to the paper alignment mechanism 67. The transfer paper conveyed to the paper alignment mechanism 67 is stapled (stitched) by the stapler 68 for each copy, and then discharged to the staple tray 69.

Next, an example of a block configuration of a control system of the image forming apparatus will be described with reference to FIG.

The selection instructing unit 1 outputs setting contents such as the mixed mode and the duplex copy mode, which are instructed by using an operation unit (not shown), to the CPU 6 through the interface circuit 5.
When the print key 2 is turned on, a start signal indicating the start of transfer is output to the CPU 6 through the interface circuit 5. The registration driving unit 3 drives the registration roller pair 44 based on a timing signal input from the CPU 6 through the interface circuit 5 to feed the photosensitive drum 31. The driving unit 4 controls the RDH2 based on a control signal input from the CPU 6 through the interface circuit 5.
1, for driving the optical system L, the retransmission mechanism Q, and the like.

When the CPU 6 is set to the mixed mode and the double-sided copy mode, the RDH 21 is driven to preliminarily circulate the placed document from the lowermost document in order to make a full cycle, and a detection result from the document size sensor 219 at the time of the preliminary circulation. Has the function of detecting the number of originals and the original size of each original, and the function of storing the detected original size in the memory 7 corresponding to each original. Also, the CPU 6 transfers the transfer paper corresponding to the image formation of the large-size document out of the two originals transferred to both sides of the transfer paper based on the storage result of the memory 7 after the preliminary circulation. It has a function of selecting the paper to be fed to the drum 31 and a function of switching the paper feed timing of the transfer paper when the originals to be transferred on both sides of the transfer paper are of a small size or a large size, as described later. That is, if the document is right-bound and the document is in A4 size, then A3 size,
In order to transfer the A-size original to the latter half of the A3-size transfer paper, the paper feed timing to the image forming means P is relatively advanced with respect to the start of scanning of the optical system L when the A4-size original is transferred. I have. Similarly, if the document is bound in the left direction and the document is in the order of A3 size and A4 size, the A4 size document is transferred to the image forming means P during the transfer of the A4 size document so that the A4 size document is transferred to the latter half of the A3 size transfer paper. The paper feed timing is set to be relatively advanced with respect to the start of scanning of the optical system L. That is,
The scanning of the optical system L is started when the rear half of the A3-size transfer paper is fed to the photosensitive drum 31. In addition, the first half of the A3 size transfer paper is transported in advance and stopped,
The transfer of the transfer paper may be resumed at the timing of starting the scanning of the optical system L.

Also, if the originals are both A3 size or A4 size,
The original is transferred to both sides of the transfer sheet as usual.

The memory 7 includes a RAM or the like, and stores a document size corresponding to each document.

Next, an example of the operation of the image forming apparatus will be described with reference to the flowchart of FIG. Note that this flowchart describes the case where the A4 size and the A3 size are mixed and the set magnification is 100%. In addition, the original is sequentially transferred from the lowest place where it is placed. That is, the transfer is performed from the back surface (first surface) of the transfer paper.

When the print key 2 is turned on after the magnification is set to 100% and the duplex copy mode is set, the RDH 21 is driven, and the originals mixedly loaded on the RDH 21 are once preliminary circulated and the number of originals is detected. Then, the count value N indicating the number of originals is stored, and the original size of each original is detected according to the detection result of the original size sensor 219. The detected original size is the first original. The lowermost document is replaced with the Nth document, and is stored in the memory 7 so as to correspond to each document (steps S1 to S4).

Subsequently, it is determined whether or not the count value N is an odd number. If the count value N is an odd number (YE in step S5)
S), if the lowest (Nth) document is A4 size, A4 size transfer paper is selected; if it is A3 size, A3 size transfer paper is selected, and this Nth document is selected as above. After one-side transfer to the transfer paper, the sheet is directly discharged to the sheet folding unit R. If the transfer paper is A3 size, Z folding is performed,
If the size is A4, Z folding is not performed, and 1 is subtracted from the count value (N = N-1) (steps S6, S7, S
8).

Next, the document sizes of the Nth document and the (N-1) th document after the subtraction are compared, and if both document sizes match (YES in step S9), that is, if both documents are A4 size A4 size transfer paper on the other hand, A3 size transfer paper on the other hand
After the transfer sheet having the size is selected, the N-th document is transferred to the back surface (first surface) of the transfer sheet, and then conveyed to the re-feed mechanism Q. The image is transferred to the front surface (second surface) (Step S10 to Step S12).

Thereafter, in step S13, 2 is subtracted from the count value N (N = N−2), and it is determined whether the count value N after the subtraction is 0, and if the count value N is 0 (step S1).
Since the transfer of all the mixed originals is completed, the transfer operation is completed and the original is discharged to the paper folding unit R. On the other hand, if the count value N is not 0 (N in step S14)
O), and return to step S9 again.

If the document sizes of the Nth document and the (N-1) th document do not match (NO in step S9), these document sizes are compared, and the Nth document is replaced with the (N-1) th document. If the size is smaller than the size (YES in step S15), the A3 size transfer paper is selected, and the Nth document is placed on the back side of the transfer paper (first side) as shown by the hatched portion in FIG. 4B) is transferred to the first half of the sheet in the conveying direction of FIG.
Is transferred onto the front surface (second surface) of the transfer paper (steps S16 to S18).

Next, 2 is subtracted from the count value N in step S19 (N = N−2). If the count value N is 0 (YES in step S20), the transfer operation is completed and the sheet is discharged to the sheet folding unit R. Then, as shown in FIG. 4C, the Z-folding is performed by the left binding that binds the leading end of the transfer paper back surface (the first surface) in the transport direction. If the count value N is not 0 (step
(NO in S20), and returns to step S9 again.

On the other hand, if the N-th document is larger than the (N-1) -th document size (NO in step S15), the A3 size transfer paper is selected, and the N-th document is shaded in FIG. Is transferred to the back surface (first surface) of the transfer paper (step
S21, S22). Subsequently, the N-1 th original is shown in FIG.
As shown by the shaded area, the transfer position is shifted to the rear half of the transfer paper surface (second surface) in the conveyance direction, and the transfer paper is transferred to the front surface.
2 is subtracted from the count value N (N = N−2) (steps S23 and S24), and if the count value N is 0 (step S23).
25, YES), the transfer operation is completed, the sheet is discharged to the paper folding unit R, and as shown in FIG. 5 (c), the Z of the transfer sheet is bound by the left binding to bind the leading end of the back surface (first surface) in the transport direction. Folding is performed. On the other hand, if the count value N is not 0 (NO in step S25), the process returns to step S9 again.

As described above, when performing Z-folding with left binding, when the size of the N-th document is larger than the size of the (N-1) -th document (NO in step S15), for example, the first sheet (N
If the (1st) original is in A4 size and the 2nd (Nth) original is in A3 size, the A4 size original is copied in the second half of the front (second side) transfer paper transport direction. Therefore, as shown in FIG. 5C, even if the Z-folding is performed by the paper folding unit R, the A4 size original after the transfer is not folded. When performing Z-folding with left binding, the first (N-1) th original is A3 size, the second (Nth)
If the originals are in A4 size order, the back side (1st
Since the A4 size original is copied in the first half of the transfer paper transport direction of the A side, the Z-folding is performed by the paper folding unit R as shown in FIG. The manuscript will not be folded.

Note that, for example, even when the B5 size and the B4 size are mixedly loaded, the processing of the above flowchart can be performed in the same manner as the case of the mixed loading of the A4 size and the A3 size.

As the means for detecting the size of the original, a plurality of light emitting elements and light receiving elements are provided below the contact glass 20 in association with each other, and the light emitted from the light emitting elements to the original by the light receiving elements is reflected on the original surface. Alternatively, the reflected light may be detected. That is, for example, one of the plurality of light-emitting and light-receiving elements is disposed below the B4 document device position in order to distinguish between the B5 size and the B4 size, and the other is arranged in the B row size and A In order to discriminate between the row size and the A3 size and the A4 size, the document is arranged below the mounting position of the A4 document outside the row B size. Then, the document size is identified based on the detection state of each light receiving element.

In the above description, Z-folding in left binding has been described. However, the present invention is sufficiently applicable to Z-folding in right binding. In this case, when the size of the document transferred on both sides of the transfer paper is in the order of small size and large size, the timing of the small size may be controlled. For example, in the flowchart of FIG. 3, the magnitude relation of step S15 may be reversed.

The Z-folding is not limited to the paper folding unit R and may be performed manually.

〔The invention's effect〕

The present invention relates to a case where the originals to be transferred on both sides of the rear end binding (right binding) and the transfer paper are in the order of small size and large size, or the originals to be bound at the front end (left binding) and both sides of the transfer paper are large size. In the case of the small size document, the image forming means feeds the image at the latter half of the transfer sheet in the transfer direction of the transfer sheet in advance of the scanning timing of the optical system at the time of transferring the small size document. Therefore, even if the Z-fold is performed as the post-processing paper folding, the transfer portion of the small-sized document is not folded by the Z-fold, so that the document is easily read and the appearance is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a control system of the image forming apparatus according to the present invention, FIG. 2 is a schematic configuration diagram illustrating an example of the image forming apparatus according to the present invention, and FIG. 4 and 5 are flowcharts showing an example of the operation of the apparatus.
FIGS. 6A and 6B are diagrams for explaining the operation of the image forming apparatus according to the present invention, and FIGS. 6A and 6B are diagrams for explaining a conventional problem. 1 ... Selection instruction unit, 2 ... Print key, 3 ... Registration drive unit, 4 ... Drive unit, 5 ... Interface circuit, 6 ... CPU, 7 ... Memory, 21 ... Circulation type automatic document feed Device (RDH), 44: Registration roller pair, 219: Document size sensor, L: Optical system, P: Image forming means, Q
...... Resending mechanism, R ... Folding unit, S ... Staple unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-309976 (JP, A) JP-A-2-74961 (JP, A) JP-A-2-89068 (JP, A) 61549 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 510-534 G03G 15/00 303 G03G 15/36 G03G 21/00 370-540 G03G 21/02- 21/04 G03G 21/14 G03G 21/20 G03G 15/00 106

Claims (1)

(57) [Claims] 1. A recirculating automatic document feeder for automatically feeding large and small size documents, image forming means for forming an image by scanning with an optical system, and first and second transfer papers for feeding the document. The transfer paper transferred to the first side is transferred to the first side to transfer to the second side.
An image forming apparatus having a re-sending function of conveying the sheet in the reverse direction with the rear end portion in the transfer sheet conveying direction at the time of forming the surface image and re-feeding the sheet to the image forming means; Means, a detecting means for detecting the size of each document at the time of the preliminary feeding, a storage means for storing the detected size of the document, and a large-size document of the large-size document transferred to both sides of the transfer paper. Transfer selecting means for selecting to feed a transfer sheet of a size corresponding to image formation, and leading edge binding to the leading end side in the transfer sheet transport direction at the time of first-side image formation or transfer sheet transport direction at the time of first-side image formation It is possible to perform binding on the rear end side. When the originals to be bound on the rear end and transferred to both sides of the transfer paper are in the order of small size and large size, or when the originals to be bound at the front end and transferred to both sides of the transfer paper are large. If the size is smaller, Timing for feeding the image forming means relative to the start of scanning of the optical system at the time of transfer of the small-size document so as to transfer the original to the second half of the transfer paper in the transfer paper transport direction. An image forming apparatus comprising a control unit.