JPH08245003A - Paper feeding timing controller of image forming device - Google Patents

Abstract

PURPOSE: To assuredly successively feed, with high efficiency, a plurality of papers whose feeding intervals are different. CONSTITUTION: A tab paper insertion mode setting key is arranged on the operation panel of a copier main body 1. Tab paper is fed from the paper feeding tray 61 of a paper feeder 6, and normal paper is fed from a paper feeding tray 62 in a tab paper insertion mode. When a paper feeding switch is executed between the tab paper and the normal paper during a copying process, a paper feeding interval is calculated by adding or subtracting difference of carrying time based on the difference between the lengths of carrying passages to a pair of resist rollers between the paper feeding tray 61 and the paper feeding tray 62, to or from the paper feeding interval of the previously fed paper, and paper fed this time is fed at predetermined timing based on the calculated result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a plurality of paper feeding units for accommodating paper sheets having different paper passing forms, and is used for performing image forming processing by alternately feeding paper sheets from both paper feeding units. The present invention relates to a paper feed timing device of an image forming apparatus that controls paper feed timing.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus provided with a plurality of paper feed units having different paper feed path lengths to a pair of registration rollers, when the paper feed units are switched during continuous copying, the above paper feed path lengths differ. A paper feed control method has been proposed that corrects the deviation of the paper feed timing based on the above, and prevents a decrease in processing efficiency during continuous copying.

For example, in Japanese Unexamined Patent Publication No. 2-147547, when sheets of the same size are separately stored in a plurality of sheet feeding units, the sheet is first conveyed in a continuous copying process using sheets of this size. If you feed paper from a paper feed cassette with a long path length and then switch to another paper feed cassette midway, the first paper feed timing of the paper feed cassette will change to the previous paper feed cassette and the current paper feed cassette. There is shown a paper feed control method for delaying a paper feed path difference caused by a difference in paper feed path length between the paper feed path and the paper feed path length so that the subsequent paper does not overlap the previous paper when the paper feed cassette is switched.

[0004]

By the way, in an image forming apparatus such as a copying machine, a tab paper is recently placed on a predetermined position (predetermined page) of a copy from a user side as the apparatus becomes multifunctional and highly functional. There is a demand for a function for automatically inserting.

Even in a conventional copying machine, if tab paper and normal transfer paper (hereinafter referred to as plain paper) are set in a plurality of paper feeding units, it is possible to feed tab paper and plain paper respectively. However, since it does not have a dedicated processing mode, it is not possible to copy while inserting the tab sheet into the predetermined position automatically.

Therefore, it is conceivable to provide a dedicated processing mode for automatically inserting a tab sheet at a predetermined position of a copy (hereinafter referred to as a tab sheet insertion mode) to enhance the functionality of the copying machine. When the above is embodied, there arises a problem of sheet feeding timing due to the difference in sheet shape and sheet feeding position.

That is, as the time required for the image forming process differs between the tab sheet and the plain sheet, the sheet feeding interval during continuous sheet feeding also differs. For this reason, when tabbed paper and plain paper are mixed and continuously fed, the paper feed interval must be changed when switching between tabbed paper and plain paper. (1) Copying efficiency does not become appropriate just by changing the paper feed interval for the paper that should be fed this time. (2) Since the copying process of the currently fed paper is faster than the copying process of the previously fed paper. There is a possibility that a problem may occur in which both sheets overlap each other during the processing to cause a jam.

Here, the cause of the difference in the time required for the image forming process between the tab paper and the plain paper will be described. For example, in the case where the paper feed cassettes are arranged in multiple stages, the conveyance from each paper feed cassette to the registration roller pair is performed. Since the path lengths are different, the conveyance time from the paper feed cassette to the pair of registration rollers differs depending on the paper feed cassette that stores tab paper and plain paper.

Further, since the tabs of the tab sheet are projected on the side edges in the longitudinal direction of the sheet, the tab sheet ends are aligned with the registration roller pair at the time of primary sheet feeding, and the sheet alignment process at the time of discharging to the discharge tray is performed. Considering paper processing such as punching and stapling, when feeding tabbed paper,
Paper is fed from the paper feed cassette in a horizontal direction (direction that is longer than the carrying direction), with the side edge without tabs on the front side, and after fixing processing, the side edge with tabs is on the front side. It becomes necessary to reverse (switch back) the direction.

When tab sheets and plain paper are mixed and continuous copying is performed, switchback processing may be performed for all, but if this is done, it takes a long time to perform copying processing for each sheet, Since it violates the request for high-speed copying processing, it is desirable to perform switchback processing only on tab paper. However, if only the tab paper is switched back, the transport time in the ejection process after image formation becomes longer for the tab paper than for the plain paper,
The transport time also varies in the discharge process.

As described above, since the time required for the image forming process from the start of sheet feeding to the completion of sheet discharging differs between the tab sheet and the plain sheet, the sheet feeding interval during continuous sheet feeding also changes accordingly.

As a solution to the above problem, the above-mentioned Japanese Patent Laid-Open No.
Although it is possible to adopt the paper feed control method described in Japanese Patent Laid-Open No. 147547, this paper feed control method considers only the optimization of the transport time at the time of paper feed, and therefore, the tab paper in the ejection process. It is difficult to reliably prevent a paper jam that occurs due to a difference in transport time between the paper and plain paper.

It is also conceivable to apply a paper feed control method in which every time the type of paper is switched, the preceding paper is completely ejected and then the subsequent paper is fed, but this method switches the paper. Each time unnecessarily lengthens the paper feed interval,
Copying efficiency will decrease.

The present invention has been made in view of the above problems, and provides a paper feed timing control device for an image forming apparatus capable of reliably and highly efficiently mixing and continuously feeding different types of paper. The purpose is to

[0015]

According to the first aspect of the present invention,
A first sheet storage section for storing a first sheet in which normal sheet conveyance is performed and a second sheet storage section for storing a second sheet in which sheet transfer is performed for a longer time than the above-described normal sheet conveyance A paper feed timing control device of an image forming apparatus in which each paper is fed to a paper feed path by being selectively switched from the paper storage unit of the first paper feed unit, and the first paper is fed at a first paper feed interval. And the second sheet is set to the second sheet longer than the first sheet feeding interval.
Paper feed means for feeding paper at a paper feed interval of
Switching instructing means for instructing switching of paper feeding with other sheets,
When a paper switching instruction is issued between the second paper and the second paper, a paper feed adjusting means for setting the paper feed interval of the first paper after the switching instruction to the paper feed interval of the previously fed paper. It is equipped with.

According to a second aspect of the present invention, in the sheet feeding timing control device, the first sheet storage section is configured such that it takes a first sheet conveyance time to convey the sheet to the image forming section. The second paper storage unit is configured such that it takes a second transfer time longer than the first transfer time to transfer the paper to the image forming unit, and the paper feed adjusting unit transfers the first paper to the second paper. When the switching to the sheet is instructed, the sheet feeding interval of the first sheet of the second sheet after the switching instruction is set to the first sheet feeding interval by the first transport time and the second transport time. When the switching is performed from the second sheet to the first sheet with the sheet feeding interval added with the time difference, the sheet feeding interval of the first sheet after the switching instruction is changed to the second sheet feeding interval. The paper feed interval is obtained by subtracting the time difference from the paper feed interval.

[0017]

According to the first aspect of the invention, when the sheets are continuously fed from the first sheet storage section, the first sheet is the first sheet.
When the paper is fed at the paper feed interval T _A of, and the paper is continuously fed from the second paper storage unit, the second paper is fed at the second paper feed interval T _B. Further, when a sheet switching instruction is issued between the first sheet and the second sheet during continuous sheet feeding, the first sheet after the switching instruction is fed at the sheet feeding interval of the sheet previously fed. It

That is, when the sheet switching is instructed from the first sheet to the second sheet during continuous sheet feeding, the first sheet of the second sheet after switching is fed at the first sheet feeding interval T _A. Paper and second
When the sheet switching is instructed from the sheet to the first sheet, the first sheet after the switching is fed at the second sheet feeding interval T _B.

According to the second aspect of the present invention, when the switching from the first sheet to the second sheet is instructed, the first second sheet after the switching instruction is the first sheet feeding. The time difference Δ between the first transport time T1 and the second transport time T1 ′ in the paper interval T _A.
T1 = | T1-T1 '| feeding interval T _B obtained by adding' =
When the sheet is fed at (T _A + ΔT1) and switching from the second sheet to the first sheet is instructed, the first sheet of the first sheet after the switching instruction has the second sheet feeding interval T. Time difference from _B above Δ
Is fed by feeding interval T _A obtained by subtracting _{T1 '= (T B -ΔT1)} .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall block diagram showing an example of a copying machine (image forming apparatus) equipped with a paper feed timing control device according to the present invention.

The copying machine shown in the figure is a mode in which a copy can be made while inserting a tab sheet (special sheet having tabs protruding on the side edges of the sheet) at a specified position (page) (hereinafter referred to as "copy"). , Tab paper insertion mode) can be set,
In the copy process in this tab sheet insertion mode, the copy position of the original (normal original page or tab sheet inserted page)
The sheets to be fed are switched to plain sheets and tab sheets in accordance with the above, and the image forming process is performed based on the preset copying process.

In the figure, a contact glass 11 as a document placing plate is attached to the upper surface of the main body 1 of the copying machine, and an automatic document feeder 2 for automatically feeding a document on the contact glass 11 is opened and closed. It is arranged as possible. The automatic document feeder 2 also functions as a tab sheet insertion position input means, as will be described later.

An operation panel (not shown) is provided on the upper surface of the copying machine main body 1, and various copy modes such as double-sided copying, reduction / enlargement, selection of the number of copies, paper size and paper feed tray, The tab sheet insertion mode can be set.

An optical mechanism 3 is provided in the upper part of the copying machine main body 1, an image forming device 4 is provided in the middle part, and a sheet re-feeding device 5 is provided in the lower part. Further, a paper supply device 6 for supplying paper for image formation is disposed on the right side surface of the main body, and a paper processing device for performing processing such as sorting, punching and stapling on the paper (copy) after image formation on the left side surface. 7 are provided.

The automatic document feeder 2 includes a document placing portion 21, a document feeding portion 22, a document feeding portion 23, from the left end side to the right end side.
The document reversing unit 24 and the first document discharging unit 25 are arranged in this order. The document placing section 21 is a part on which a document is set. The document feeding section 22 is arranged so that the originals set on the document placing section 21 are transferred to the contact glass 1 one by one from the upper surface side.
It is one that is sent to the top. A document set detection sensor 221 and a registration switch 222 are provided at appropriate places of the document feeding section 22.
Are provided, and the presence or absence of a document on the document placement section 21 is detected by the document set detection sensor 221.
In step 2, whether or not the document is fed is detected.

The document feeder 23 conveys the document fed by the document feeder 22 to a predetermined document placement position on the contact glass 11, ejects the document after the copying process, and turns it over. Then, the original document is conveyed to the original document reversing section 24 so as to be conveyed to the original document placement position. A second document ejection unit 231 is provided on the upper surface of the document conveyance unit 23 for ejecting the document after completion of copying in the reverse page order of the document set on the document placement unit 21.

The document reversing unit 24 is provided with a reversing guide 241 forming a reversing path, and the document conveyed from the document conveying unit 23 is reversed so that the document is reversed upside down and set at the document placing position. While returning to the transport unit 23,
The document conveyed from the document conveying unit 23 is fed to the first document discharging unit 2
5 or the second document output unit 231.

The first original document ejecting section 25 is an ejecting section for ejecting the original document after completion of copying without changing the page order of the original document set on the original document placing section 21.

The optical mechanism 3 comprises a first optical system 31, a second optical system 32, a lens system 33 and a reflecting mirror 34, and divides the original image into slits and guides it to the image forming apparatus 4. The first optical system 31 includes a halogen lamp, a reflector, and a reflecting mirror, and illuminates a document placed at the document placement position, and guides reflected light from the document to the second optical system 32. The second optical system 32 is composed of two reflecting mirrors, and guides the reflected light from the document, which is guided through the first optical system 31, to the lens system 33. The lens system 33 forms an original image on the photosensitive drum 41 of the image forming apparatus 4. The reflecting mirror 34 guides the reflected light from the original that has passed through the lens system 33 to the photosensitive drum 41.

The first optical system 31 and the second optical system 32 are reciprocally movable along the contact glass 11 with a predetermined space by a drive motor (not shown), and are placed at the document placing position. The original is scanned in the main scanning direction (direction A in the figure), and the entire original image is projected on the photosensitive drum 41.

The image forming apparatus 4 includes a photosensitive portion including a photosensitive drum 41, a main charging portion 42, a developing portion 43, and a transfer portion 4 around the photosensitive drum 41 in order from the upstream side in the rotation direction.
4, a separation unit 45, a cleaning unit 46, a conveyance unit 47, a fixing unit 48, a conveyance path switching unit 49, and a sheet feeding unit 50 are arranged, and the conveyance unit 46 is a lower portion of the photoconductor drum 41 and The sheet feeding section 50 is arranged on the downstream side of the separating section 45, and is arranged on the lower side of the photosensitive drum 41 and on the upstream side of the transfer section 44. The fixing unit 48 and the transport path switching unit 49 are arranged in this order at the downstream end of the transport unit 47.

The photosensitive drum 41 forms an electrostatic latent image of the original image irradiated by the optical mechanism 3. The main charging unit 42 uses the photosensitive drum 41 to form the electrostatic latent image.
Is charged to a predetermined potential. The developing section 43 electrostatically attracts toner to the latent image of the original formed on the photosensitive drum 41 to make the original image visible. Transfer unit 4
Reference numeral 4 denotes an image formed by transferring the visible image (toner image) of the document formed on the photosensitive drum 41 to the sheet fed from the sheet feeding device 6 via the sheet feeding unit 50. The separation unit 45 separates the image-formed sheet from the photosensitive drum 41. The cleaning unit 46 removes the toner remaining on the photosensitive drum 41 after the image formation.

Further, the conveying section 47 conveys the sheet separated from the photosensitive drum 41 to the fixing section 48, and the fixing section 48 comprises a heating roller 481 and a pressure roller 482 which are pressed against each other and are transferred onto the sheet. The toner image is fused and fixed by heat.

Further, the transport path switching section 49 switches the transport path of the sheet after the image formation and switches back the transport direction of the sheet to discharge it. As described below,
In the tab sheet insertion process of the tab sheet insertion mode, the conveyance path switching unit 49 is provided with a switchback function in order to eject the tab sheet by reversing the front and rear of the conveyance direction.

The transport path switching section 49, as shown in FIG.
The discharge path R1 is composed of a switching plate 491 having a triangular cross section and guide plates 492 to 494 arranged opposite to each side of the switching plate.
Three conveyance paths, that is, the circulation path R2 and the reverse discharge path R3, are formed, and the conveyance roller pairs 495 to 497 are provided at the input end and the two output ends of the conveyance path switching unit 49, respectively.

The switching plate 491 is a discharge position (a position that shields the circulation path R2; indicated by a dotted line in the figure) and a circulation position (a position that shields the discharge path R1; a solid line in the figure) by a solenoid (not shown). The switch passage 491 is switched between the discharge path R1 and the circulation path R2 by switching the position of the switch plate 491.

The discharge path R1 is a conveyance path for discharging the copy-processed paper to the paper discharge port 12 provided at an appropriate place on the left side surface of the apparatus main body 1, and the circulation path R2 is the first copy (two-sided copy). It is a conveyance path for conveying the paper (copying on the front side) finished (hereinafter referred to as single-sided copied paper) to the re-feeding device 5 side, and the reversal discharge path R3 transfers the switched-back paper to the paper discharge port 12 described above. This is the transport path for discharging.

When a single-sided copying process is performed on plain paper, the switching plate 491 is set at the discharge position and the fixing unit 4
The plain paper discharged from the sheet 8 is discharged to the sheet processing device 7 through the discharge path R1. Further, when the double-sided copy process is performed on the plain paper, the switching plate 491 is set to the circulation position in the first copy (front surface copy), and the plain paper discharged from the fixing unit 48 is passed through the circulation path R2. In the second copying (back side copying), the switching plate 491 is conveyed to the sheet re-feeding device 5, the switching plate 491 is switched to the discharging position, and the plain paper discharged from the fixing unit 48 is transferred to the paper processing device 7 through the discharging path R1. Is discharged.

The tab sheet switchback in the tab sheet insertion processing is performed by setting the switching plate 491 at the circulation position and controlling the driving of the conveying rollers. That is,
When the tab sheet is fed, the switching plate 491 is set to the circulation position, and the tab sheet ejected from the fixing section 48 is conveyed to the sheet re-feeding device 5 side through the circulation path R2. At this time,
The conveying roller pair 497 conveys the tab sheet by at least the lengthwise length thereof to the sheet re-feeding device 5 side, and then the driving direction is reversed with the tab sheet held therebetween. As a result, the tab sheet is reversed in the front-back direction and is discharged to the sheet processing device 7 through the reverse discharge path R3.

The sheet conveying section 50 is composed of a pair of registration rollers 501 and a sheet guide 502 which form a conveying path.
The sheet that is primarily fed from the sheet feeding device 6 in order to transfer / form an original image on the sheet is set to the photosensitive drum 41 at a predetermined timing.
It is a secondary paper feed. A paper guide 503 for the paper fed from the paper supply device 6 and a paper guide 504 for the paper re-fed from the paper refeeding device 5 are joined at the upstream end of the paper guide 502. When double-sided copy processing is performed on plain paper, in the first copy (front surface copy), the paper fed from the paper supply device 6 is conveyed to the registration roller pair 501 via the paper guide 503,
In the second copying (back side copying), the single-sided copied sheet re-fed from the sheet re-feeding device 5 is conveyed to the registration roller pair 501 via the sheet guide 504.

The sheet re-feeding device 5 includes sheet guide parts 51, 5
5, the paper reversing unit 52, the intermediate tray 53, and the paper re-feeding unit 54. In the double-sided copying mode, the second copying (back side copying) is performed on the single-sided copied paper.
The single-sided copied sheet is re-fed to the image forming apparatus 4. The paper guide unit 51 guides the single-sided copied paper conveyed through the circulation path R2 of the conveyance path switching unit 49 to the paper inverting unit 52, and the paper inverting unit 52 guides the front and back sides of the single-sided copied paper. Inverted, intermediate tray 5
Reference numeral 3 temporarily stores the one-sided copied paper.

The sheet reversing section 52 is provided for reversing the one-side copied sheet an odd number of times during re-feeding. The one-side copied sheet is turned upside down a total of three times in the circulation path R2 of the transport path switching section 49, the sheet reversing section 52, and the sheet guide section 55 of the re-feeding device 5, and the second copying side is the first time. It is designed to be the opposite of the copy surface.

Further, the paper refeed unit 54 is provided with the intermediate tray 53.
The single-sided copied paper stored in the paper is re-fed at a predetermined timing, and the paper guide section 55 guides the re-fed single-sided copied paper to the paper conveyance section 50 of the image forming apparatus 4. Is.

The paper feeding device 6 is composed of three lifting type paper feeding trays 61, 62, 63 and one manual insertion tray 64 which are vertically arranged in multiple stages, and constitutes the tab paper feeding means according to the present invention. ing. The paper tray 61 having the maximum capacity is arranged at the lowermost stage, the manual insertion tray 64 is arranged at the uppermost stage, and the paper trays 61, 62, 63 or the manual insertion tray 64 store plain paper or tab paper.

The paper feed trays 61 to 63 are respectively capable of moving up and down, and the paper placing bases 611 to 631 and the paper placing bases 611 to 61, respectively.
Sheet feeding units 612 to 632 for feeding the sheets placed on the sheet 31
The sheet feeding units 612 to 632 are provided on the upper portions of the sheet placing tables 611 to 631 on the leading edge side of the sheet.
A paper discharge port 65 is provided on the downstream side of the paper feed unit 611 of the lower paper feed tray 61, and the paper from the paper supply device 6 is fed from the paper discharge port 65 to the paper transport unit 50 of the image forming apparatus 4. It is supposed to be done. In addition, the paper feeding device body 6
A paper guide portion 66 is provided above the paper discharge port 65 on the front side surface (the left side surface in the drawing) of the above. The paper guide section 66 conveys the paper fed from the manual insertion tray 64 and the upper and middle paper feed trays 62 and 63 to the paper discharge port 65.

Each of the sheet feeding units 612, 622, 632 is equipped with pickup rollers 612A, 622A, 632A and sheet feeding rollers 612B, 622B, 632B, and the sheets placed on the sheet trays 611-613 or the manual tray 64 are placed. Of the uppermost sheet of paper, the pickup roller 6
12A to 632A to pick up and feed rollers 612B to 6
Paper is fed by 32B. The paper fed from the lower paper feed tray 61 is conveyed from the paper discharge port 65 to the paper conveyance section 50 in the apparatus main body 1, and is fed from the manual insertion tray 64 and the upper and middle paper feed trays 62 and 63. The sheet is conveyed to the sheet discharge port 65 by the sheet guide unit 66, and then is conveyed from the sheet discharge port 65 to the sheet conveyance unit 50 in the apparatus main body 1.

As described above, since the paper feed trays 61 to 63 have different conveyance path lengths from the paper feed start position to the registration roller pair 501, the conveyance time to the registration roller pair differs between the paper feed trays 61 to 63. There is. Also, the paper feed tray 6
When the sheets set to 1 to 63 are tab sheets, a switchback process is performed at the time of ejection in the tab sheet insertion process, and thus the tab sheet takes a longer ejection time than plain paper.

Therefore, the transport time and the discharge processing time differ depending on the position of the paper feed tray and the type of paper set in each paper feed tray, and accordingly the paper feed of the paper feed trays 61 to 63 during continuous paper feed. Different intervals are set.

For example, when the lower paper feed tray 61 is a plain paper tray and the middle paper feed tray 62 is a tab paper tray, the tab paper has a longer transport time and a longer ejection processing time than the plain paper. The time required for processing from the start of paper feeding to the end of discharge is long. Therefore, the sheet feeding interval T _B for continuous sheet feeding to the sheet feeding tray 62 is set longer than the sheet feeding interval T _A for continuous sheet feeding to the sheet feeding tray 62.

FIG. 3 is a diagram showing an example of the sheet feeding interval of the plain paper tray, and FIG. 4 is a diagram showing an example of the sheet feeding interval of the tab sheet tray.

In FIGS. 3 and 4, sheet positions s, a,
b and e are a paper feed start point, an image formation start point, a discharge process start point, and a discharge end point, respectively. Further, the sheet feeding timing tr (r = 1, t2, ... N) indicates the sheet feeding timing of the r-th sheet, and the symbols to are from sheet feeding start to image formation start, from image formation start to discharge start, and discharge processing start, respectively. It is a period corresponding to each process from (1) to completion of discharge (including switchback processing during this period). Further, T _A indicates a paper feed interval during continuous paper feed on plain paper, and T _B indicates a paper feed interval during continuous paper feed on tab paper.

As described above, since the conveyance path to the registration roller pair 501 is long for the tab sheet and there is a switchback process, it takes a longer time than the plain sheet process, so that the tab sheet is fed. The interval T _B is longer than the paper feed interval T _A for plain paper.

The sheet processing device 7 performs sheet processing such as simple sheet discharging, sorting, punching and stapling. A sheet discharging tray 71 is provided on the upper surface and a sorter section 72 including a plurality of bins 721 is provided on the left side surface. Is provided,
A paper processing unit 73 that performs punching and stapling processing is provided in the lower portion of the apparatus, and a paper guide unit 74 that conveys a paper is provided above the paper processing unit 73.

FIG. 5 is a block diagram relating to paper feed timing control in the tab paper insertion mode of the copying machine according to the present invention. In the figure, the same members as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

The CPU 100 is a control unit for centrally controlling the copying operation of the main body of the copying machine, and controls the drive of the optical mechanism 3, the image forming device 4 and the paper feeding device 6 to perform the image forming process and the tab sheet inserting process for each original. Is to do. Also, C
The PU 200 is a control unit for centrally controlling the document transport operation of the automatic document transport device 2. CPU100 and CPU200
Are capable of communicating data with each other, and are capable of communicating necessary information with each other.

The CPU 200 is an original set detection sensor 22.
The presence / absence of a document to be processed is determined based on the detection signal 1 and the number of fed documents is counted by the built-in counter 202 based on the detection signal from the registration switch 222. In the tab paper copy mode,
Data of the tab sheet insertion position is read in advance by the automatic document feeder 2. To read this data,
For example, a document in which a special document with a read code or a read mark is inserted at the tab sheet insertion position (inserted page) is conveyed by the automatic document feeder 2 and the special document detection switch 223 detects the above-mentioned special document. Be seen. CPU20
0 calculates the tab sheet insertion position based on the detection signal of the special document detection switch 223 and the detection signal of the registration switch 222, stores the calculation result in an internal memory (not shown), and sends it to the CPU 100.

Further, the CPU 100 constitutes the paper feed timing control means according to the present invention. CPU100
In the tab sheet insertion mode, the tab sheet insertion position detection unit 101 (discriminating means) determines whether or not the current copy processing is the switching position between the plain sheet and the tab sheet for each copy processing, that is, the current sheet feeding. When it is determined whether the paper to be fed is the same as the previously fed paper and it is determined that the paper to be fed this time is different from the previously fed paper, the paper feed interval calculation unit 1
The paper to be fed this time is fed at the paper feed timing based on the paper feed interval calculated by 02 (paper feed interval calculation means).

The tab sheet insertion position detector 101 detects the tab sheet insertion position data read from the CPU 200 in advance before the actual copying process and the CPU 200 in the actual copying process.
Based on the data of the number of transported originals input from, it is determined whether or not the switching position is between the normal original and the tab sheet. Further, the paper feed interval calculation unit 102 calculates the paper feed interval (T _A or T _B ) when continuously feeding the previously fed paper, the transport time TF1 for the plain paper feed tray 61, and the tab paper feed tray. The feeding interval of the sheets to be fed this time is calculated from the conveyance time TF2 for 62.

In the tab sheet insertion mode, the CPU 100 feeds plain paper from the sheet feeding device 6 during copying of a normal document, and from the sheet processing device 6 during copying at the tab sheet insertion position. Feed tab paper. Also, C
When the PU 100 feeds the tab sheet, the PU 100 conveys the conveyance path switching unit 4
When the tab sheet is conveyed to the conveyance roller pair 497 via the circulation path R2 while the switching signal of 9 is sent to switch the conveyance path to the circulation path R2, the driving direction of the conveyance roller pair 497 is changed at a predetermined timing. Invert to switch back the tab sheet conveyance direction.

Next, the paper feed timing control in the tab paper insertion mode will be described. In this embodiment, the case where the lower paper feed tray 61 is a plain paper tray and the middle paper feed tray 62 is a tab paper tray will be described as an example. It should be noted that the plain paper continuously fed from the plain paper tray is copied according to the diagram shown in FIG. 3, and the tab paper continuously fed from the tab paper tray is copied according to the diagram shown in FIG. Shall be given.

FIG. 6 is a diagram in the case where the tab sheet and the plain sheet are continuously fed at the corresponding sheet feeding intervals during the continuous sheet feeding in the tab sheet copying mode.

Since the paper feed interval T _B for the tab sheet is longer than the paper feed interval T _{A for} the plain paper, when the plain paper is switched to the tab paper, the paper feed interval T _{B as} shown in FIG.
Even if the tab sheet is fed with, the tab sheet does not catch up with the plain sheet during the copying process (the tab sheet discharge processing start P _B is always after the plain sheet discharge end point), and the paper jam problem occurs. However, the sheet feeding interval at the time of switching the tab sheet becomes unnecessarily long and the processing efficiency is lowered. On the other hand, when the tab sheet is switched to the plain sheet, when the plain sheet is fed at the sheet feeding interval T _A , the plain sheet catches up with the tab sheet in the process of (the plain sheet ejection processing is started during the tab sheet ejection processing period. P _a enters.), which may cause a paper jam.

Therefore, in the tab sheet insertion mode, in order to carry out continuous copying without causing a paper jam and at a suitable processing efficiency, when the plain paper or the tab sheet is continuously fed, the plain sheet or the tab sheet is supplied. The paper may be fed at the paper feed interval T _A or the paper feed interval T _B corresponding to the paper, but when the paper is switched between the plain paper and the tab paper, a special paper feed interval different from the above paper feed intervals T _A and T _B is used. It is necessary to feed plain paper or tab paper at the paper feed intervals T _A ′ and T _B ′.

FIG. 7 is a time chart when the tab sheet copy mode and the plain sheet are fed at a sheet feed interval different from that during continuous sheet feed in the tab sheet copy mode.

In the figure, the vertical axis indicates the type of continuously fed paper, and the horizontal axis indicates time. Also, s,
Reference characters a, b, and e are a paper feed start point, an image formation start point, a discharge process start point, and a discharge end point of each sheet, and T1 and T3 are s-a and b-e in plain paper copy processing. , T1 'and T3' are the time required between sa and bee in the tab sheet copying process, and T2, respectively.
Is the time required between a and b in the copying process of plain paper and tab paper. Further, T _A and T _B are the paper feed intervals when the plain paper and the tab paper are continuously fed, T _A ′ is the paper feed interval when the plain paper is fed next to the tab paper, and T _{B ′.} ′ Is the paper feed interval when the tab paper is fed next to the plain paper.

The period between the paper feed start point s and the image formation start point a includes the transport times TF1 and TF2 of plain paper or tab paper up to the registration roller pair 501, and as described above, for tab paper. Since the transport time TF2 is longer than the transport time TF1 for plain paper, T1 '> T1.
Further, the period between the discharge process start point b and the discharge end point e includes the switchback process in the transport direction, and the tab sheet is reversed as described above, so that T2 ′> T2. The period between the image forming start point a and the discharge processing start point b is almost the time from when the secondary sheet feeding to the photosensitive drum 41 is started to when the sheet passes through the fixing section 48, and the processing speed during this period is constant regardless of the type of sheet. Therefore, the tab paper and the plain paper are the same.

In the tab sheet insertion mode, in order to carry out continuous copying with suitable processing efficiency without causing a sheet jam, as shown in FIG. Since it is preferable to start the discharge process of the next sheet at the same time as the discharge end point e or after a certain time δ, calculate the sheet feeding intervals T _A ′ and T _B ′ at the time of sheet switching that satisfies this. , As follows.

That is, in the figure, T1 + T2 + T
3 = Ts, T1 '+ T2 + T3' = Ts', T1'-T
When 1 = ΔT1, the paper feed intervals T _A ′ and T _B ′ are given by the following equations (1) and (2).

[0069]

[Equation 1]

On the other hand, since the sheet feeding intervals T _A and T _B are given by the following equations (3) and (4), these equations (3) and
By substituting the equation (4) into the equations (1) and (2), the sheet feeding intervals T _A ′ and T _B ′ are respectively given by the following (5),
Equation (6) is obtained.

[0071]

[Equation 2]

[0072]

(Equation 3)

In the above equations (5) and (6), ΔT
Since 1 corresponds to the difference between the transport time TF2 for tab sheets and the transport time TF1 for plain paper, as can be seen from both equations, when two types of sheets having different sheet feeding intervals are switched and fed, the transport time is When switching from a long paper to a paper with a short transportation time, feed the paper that should be fed this time at the paper feeding interval that is the paper feeding interval for the previously fed paper plus the difference of the transportation time, and It is understood that when the sheet is switched to a sheet having a long transport time, the sheet to be fed this time should be fed at the sheet feed interval obtained by subtracting the difference in the transport time from the sheet feed interval for the sheet previously fed.

In this embodiment, the transport time T for the tab sheet is
Since F2 has set the sheet cassette to be longer than the transfer time TF1 on plain paper, when switching on plain paper from the tab paper, the difference in transfer time to the paper feed interval T _B for the tab sheet Delta] T1 (= T1 When the plain paper is fed at the paper feed interval T _A ′ obtained by adding “−T1> 0) and the plain paper is switched to the tab paper, the difference ΔT1 in transport time is subtracted from the paper feed interval T _A for the plain paper. The tab sheet is fed at the sheet feeding interval T _B ′.

FIG. 8 is a flow chart for determining the paper feed interval of each paper in the tab paper insertion mode. In the tab paper insertion mode, the CPU 100 calculates the paper feed interval according to the flowchart of FIG.
Each sheet is fed at a predetermined feeding timing based on the calculation result.

In the paper feed interval calculation processing, first, the type of paper to be fed this time is determined (S1). If it is plain paper (YES in S1), the type of paper fed last time is determined. If the previous paper is also plain paper (YES in S2), the plain paper is continuously fed, so the paper feed interval T _A at the time of continuous feed of plain paper is the control value of the paper feed interval. It is set to TC (S3).

If the previously fed sheet is a tab sheet (S
2 is NO), a difference ΔT1 = | T1′−T1 | between the transport time T1 for plain paper and the transport time T1 ′ for tab paper is calculated (S4), and the paper feed interval T during continuous feeding of tab paper is calculated. the conveying time difference _{B ΔT1} = | T1'-T1 |
Is added to calculate the sheet feeding interval T _A ′ (S5), and this sheet feeding interval T _A ′ is set to the sheet feeding interval control value TC (S6).

On the other hand, if the sheet to be fed this time is a tab sheet (NO in S1), the type of the sheet previously fed is determined (S7), and if the previous sheet is also a tab sheet (S7). YES), the tab sheet is continuously fed, so that the sheet feeding interval T _B at the time of continuously feeding the tab sheet is set to the control value TC of the sheet feeding interval (S11).

If the previously fed paper is plain paper (S
No in step 7), the difference in transport time ΔT1 = | T1′−T1 |
Is calculated (S8), and further, the transport time difference ΔT1 = | T1′−T from the paper feed interval T _A when the plain paper is continuously fed.
The paper feed interval T _B ′ is calculated by subtracting 1 | (S9), and this paper feed interval T _B ′ is set to the paper feed interval control value TC (S10).

Then, in the tab sheet insertion mode, C
Each time the PU 100 feeds a sheet, the sheet feeding interval is calculated according to the flowchart of FIG. 8, and each sheet is fed at a predetermined feeding timing based on the calculation result.

In the present embodiment, since the plurality of paper feed trays 61 to 63 arranged in the paper supply device 6 and the manual insertion tray 64 have different conveyance path lengths to the registration roller pair 501, this is accompanied. Although the case where the transport time of the sheet to the forming and forming apparatus 4 is different has been described, when the transport time from each sheet feeding tray is the same, the time difference Δ of the transport time is given.
Since T1 is "0", as is clear from the above equations (5) and (6), the sheets to be fed this time at the time of sheet switching should be fed at the sheet feeding interval previously fed. You can do it.

Further, in the above embodiment, the case where the plain paper and the tab paper are mixed and continuously fed is described, but the present invention is not limited to the combination of the types of the paper, and a plurality of feeding papers are used. When a plurality of papers with different paper feed intervals are stored in the paper tray, if these papers are mixed and continuously fed, it can be applied to any paper. For example, depending on the presence or absence of so-called margin shift processing, such as when continuously feeding a plurality of plain papers with different paper feed intervals due to differences in paper size and paper quality and performing copy processing by shifting the image forming position with respect to the paper. It can also be applied to the case where a plurality of plain papers having different paper feed intervals are continuously fed.

[0083]

As described above, according to the first aspect of the invention, the image formation in which the first sheet and the second sheet having different sheet feeding intervals are selectively switched and continuously fed is formed. The paper feed timing control device of the apparatus, and when the paper switching is instructed between the first paper and the second paper, the paper feeding interval of the first paper after the switching instruction was previously fed. Since the paper feed interval is set, the second paper feed interval is long.
Even when the first sheet having a short sheet feeding interval is fed after the second sheet is fed, the conveyance interval between the first sheet and the second sheet during the image forming process is ensured, and the jam is surely performed. In addition, the sheet feeding interval at the time of switching sheets is not unnecessarily lengthened, and continuous feeding of the first and second sheets having different sheet feeding intervals can be efficiently performed.

According to the invention described in claim 2, the first
When switching from the second sheet to the second sheet is instructed,
After the switching instruction, the first sheet of the second sheet is fed at the sheet feeding interval obtained by adding the time difference between the first feeding time and the second feeding time to the first sheet feeding interval. When switching to the first sheet is instructed, the sheet feeding interval of the first sheet after the switching instruction is set to the sheet feeding interval obtained by subtracting the time difference from the second sheet feeding interval. Therefore, the unnecessary deviation of the sheet feeding interval caused at the time of sheet switching due to the conveyance time difference is appropriately corrected, and the continuous sheet feeding can be performed with a suitable sheet feeding efficiency.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an example of a copying machine (image forming apparatus) including a paper feed timing control device according to the present invention.

FIG. 2 is a schematic configuration diagram of a transport path switching unit.

FIG. 3 is a diagram showing an example of a paper feed interval of a plain paper tray.

FIG. 4 is a diagram showing an example of a sheet feeding interval of a tab sheet tray.

FIG. 5 is a block diagram relating to paper feed timing control in a tab paper insertion mode of the copying machine according to the present invention.

FIG. 6 is a diagram when tab sheets and plain sheets are continuously fed at corresponding sheet feeding intervals during continuous sheet feeding in a tab sheet copying mode.

FIG. 7 is a time chart when the tab sheet copy mode and the plain sheet are fed at a sheet feed interval different from that during continuous sheet feed in the tab sheet copy mode.

FIG. 8 is a flowchart for setting a paper feed interval for each paper in the tab insertion mode.

[Explanation of symbols]

 1 Copying Machine Main Body 11 Contact Lens 14 Tab Paper Insert Mode Setting Key 15 Copy Key 2 Automatic Document Feeding Device 21 Document Loading Unit 22 Document Feeding Unit 23 Document Feeding Unit 24 Document Reversing Unit 25 First Document Ejecting Unit 221 Document Set Detection Sensor 222 Registration switch 223 Special document detection switch 3 Optical mechanism 31 First optical system 32 Second optical system 33 Lens system 34 Reflecting mirror 4 Image forming device 41 Photosensitive section (photosensitive drum) 42 Main charging section 43 Developing section 44 Transfer section 45 Separation Unit 46 Cleaning Unit 47 Conveying Unit 48 Fixing Unit 49 Conveying Path Switching Unit 497 Conveying Roller Pair 50 Paper Conveying Unit 5 Refeeding Device 6 Paper Feeding Device 65 Paper Discharging Port 61, 62, 63 Elevating Feeding Tray 64 Hand Inserting tray 611, 612, 613 Paper loading table 612, 622, 632 Paper feeding section 6 Paper guide part 7 the sheet processing apparatus 100, 200, 300 CPU 101 tab sheet insertion position detection unit 102 feeding interval calculating unit

Claims (2)

[Claims] 1. A first sheet storage section for storing a first sheet, which is normally transported, and a second sheet, which is longer than the regular sheet transport and is transported. A paper feed timing control device of an image forming apparatus, in which each paper is fed to a paper feed path by being selectively switched from a second paper storage section for storing the first paper. Paper feeding means for feeding the second paper at a paper feeding interval and a second paper feeding at a second paper feeding interval longer than the first paper feeding interval, and feeding the first paper and the second paper When the switching instruction means for instructing switching and the sheet switching between the first sheet and the second sheet are instructed, the sheet feeding interval of the first sheet after the switching instruction is set to the sheet feeding rate of the sheet previously fed. A paper feed timing control device for an image forming apparatus, comprising: a paper feed adjusting unit configured to perform a paper feed interval. 2. The paper feed timing control device for an image forming apparatus according to claim 1, wherein the first paper storage unit is configured to require a first carrying time for carrying the paper to the image forming unit. The second paper storage unit is configured such that it takes a second transfer time longer than the first transfer time to transfer the paper to the image forming unit, and the paper feed adjusting unit transfers the first paper to the second paper. When the switching to the sheet is instructed, the sheet feeding interval of the first sheet of the second sheet after the switching instruction is set to the first sheet feeding interval by the first transport time and the second transport time. When it is instructed to switch from the second sheet to the first sheet with the sheet feeding interval added with the time difference, the first sheet of the first sheet after the switching instruction is given.
The paper feed timing control device of the image forming apparatus, wherein the paper feed interval is set to a paper feed interval obtained by subtracting the time difference from the second paper feed interval.