JPH0223172A - Picture image forming device - Google Patents

Abstract

PURPOSE:To form a both sides or a multiple picture image of a sheet having an unknown size such as a hand operated sheet, by arranging the detection means detecting a sheet size along the sheet carrying path at the upstream side in the sheet carrying direction of an intermediate sheet housing device. CONSTITUTION:The size of the sheets S carried to an intermediate tray 15 is detected with a detection means 46, and the seat size information is memorized with a memory means 50 by the signal from the means 46. And by means of a control means 49, based on the sheet size information memorized with the means 50, the sheets S, having various sizes and carried to the tray 15, are nippedly held with a carrying means 16 while the tips are slid at a given distance apiece, and then a first and a second drive means M1-M3 are controlled so that every one piece is re-feeded apiece with a re-feeding means 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer. The present invention relates to an image forming apparatus that stacks images in a staggered manner.

(0) Prior Art Conventionally, there has been known an image forming bag W (hereinafter referred to as a copying machine) in which sheets on which images have been formed are stacked on an intermediate tray with the edges of the sheets shifted by a predetermined distance. , 14th
As shown in the figure, the machine body 2 is equipped with a cassette 3 that is detachably attached to the machine body 2 and a platen 4 on which a document is placed. is installed. Then, the paper feed roller 5
A register roller pair 6 is disposed downstream of the roller pair 6, and a copying section 7 is disposed downstream of the roller pair 6. Also,
A fixing device 9 is disposed downstream of the copying section 7, and a flapper 10 is disposed downstream of the fixing device 9. Furthermore, a pair of paper discharge rollers 11 for discharging the sheet S to the outside of the machine body 2 is disposed downstream of the flapper 10, and a re-conveyance path 12 is disposed branching off from the flapper 10. 12 includes a pair of transport rollers 13, an intermediate tray 15, upper and lower reelers lea and 16b, and an upper roller le.
a is a lower roller 16b driven and rotated by a spring (not shown);
A pair of transport rollers 16, a guide 17, which are urged to press against
A sheet end sensor 19 and a pair of refeed rollers 20 consisting of upper and lower rollers 20a and 20b are provided. Furthermore, a reversing path 12 a is connected to the re-conveying path 12 from the downstream side of the flapper 10 to the upstream side of the pair of conveying rollers 13 . Further, the copying section 7 has a cylindrical photosensitive drum 21, and a negative charger 22 is provided around the drum 21.
, a developing device 23, a transfer charger 25, and a cleaner 26 are provided. Note that the copying machine 1a is equipped with a sheet size sensor (not shown) that detects the size of the sheet S stored in the cassette 3 when the cassette 3 is installed, and the conveyance timing and rotation amount of each roller pair are , is performed based on sheet size information from the sheet size sensor.

In the case of single-sided copying, when a start key (not shown) is pressed, the paper feed roller 5 starts rotating and feeds the sheet S from the cassette 3. Then, the sheet S is conveyed by a pair of register rollers 6 in synchronization with the image on the photosensitive drum 21 of the copying section 7, and the image on the photosensitive drum 21 is transferred by the transfer charger 25. Further, the sheet S has an image fixed thereon by a fixing device 9, is guided by a flapper 10 to a pair of discharge rollers 11, and is discharged to the outside of the machine body 2 by the pair of rollers 11.

Furthermore, in the case of double-sided copying, the sheet S on which the image has been copied on the first side by the same operation as described above is guided by the flapper 10 to a pair of paper ejection rollers 11, and the pair of rollers 11 transfers the image to the machine body 2.
When a sensor (not shown) detects that the sheet is transported outward and its rear end has passed through the flapper 10, the pair of sheet discharge rollers 11 is reversed. As a result, the sheet S is conveyed to the re-feeding path 12 through the reversing path 12a, held between the pair of conveying rollers 13 and conveyed to the pair of conveying rollers 16, and then conveyed by the pair of rollers 16 to the pair of re-feeding rollers 20. Based on the sheet size information from the sheet size sensor, the sheet is conveyed until the trailing edge passes through the pair of conveying rollers 13 and falls onto the intermediate tray 15. Then, the pair of conveying rollers 16 is reversed, and the sheet S is held between the pair of rollers 16 with its leading end protruding from the pair of rollers 16 by a predetermined distance. By a similar operation, the sheets S are sequentially stacked onto the intermediate tray 15 with their leading edges shifted by a predetermined distance. Then, from the intermediate tray 15, the sheet S
When refeeding, the sheets S are conveyed by the pair of conveying rollers 16 while being overlapped until the trailing edge of the lowest and first sheet S passes through the nip of the pair of rollers 16, and the sheet S is started at a predetermined timing. The roller pair 20 refeeds it to the register roller pair 6. Furthermore, an image is formed on the second surface of the sheet S by the same operation as described above, and the sheet S is discharged to the outside of the machine body 2 by a pair of paper discharge rollers 11. Thereafter, as described above, the sheet S is conveyed to the refeeding roller pair 20 by the conveying roller pair 16, which rotates until the rear end of the lowest sheet S passes through the nip of the conveying roller pair 16, and the sheet S is conveyed to the refeeding roller pair 20,
0, an image is formed on the second surface in the same manner as described above, and the paper is discharged to the outside of the machine body 2.

(C) Problems to be Solved by the Invention By the way, in the copying machine 1a described above, by installing the cassette 3 in the machine body 2, the sheet size sensor detects the size of the sheet S stored in the cassette 3. , When the manual feed function is added, the size of the manual feed sheet cannot be detected. Therefore, since predetermined operations cannot be performed on the intermediate tray 15, there is a drawback that double-sided or multiple copying of manually fed sheets is not possible.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus in which the size of a sheet is detected by a detection means during a sheet conveyance path, thereby solving the above-mentioned problems.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances. For example, referring to FIGS. 1 and 2, the sheet (S) on which an image has been formed is Alternatively, a re-conveying path (12) for re-conveying sheets to form multiple images, an intermediate sheet storage device (15) disposed in the re-conveying path (12), and sheets loaded on the intermediate sheet storage device (15). A conveyance means (16) that shifts the leading edge of the sheet (S) by a predetermined distance and holds it; a first drive means (Ml) that drives the conveyance means (16); a refeeding means (20) for refeeding the sheets (S) to be processed one by one; and the refeeding means (20).
An image forming apparatus (1) comprising a second driving means (M2, M3) for driving the intermediate sheet storage device (M2, M3).
15) Detection means (46) for detecting the size of the sheet arranged along the sheet conveyance path on the upstream side in the sheet conveyance direction
and a storage means (50) for storing sheet size information detected by the detection means (46); and a storage means (50) for storing sheet size information detected by the detection means (46);
5) The conveying means (16) shifts the leading ends of the sheets (S) of various sizes by a predetermined distance and holds them, and the re-feeding means (20) re-feeds them one by one. The first and second driving means (Ml,
A control means (49) for controlling M2, M3).

(f) Effect Based on the above configuration, the size of the sheet (S) conveyed to the intermediate tray (15) is detected by the detection means (46), and the storage means (5o) is stored in accordance with the signal from the detection means (46). Store sheet size information. And the control means (
49) shifts the leading edge of sheets (S) of various sizes conveyed to the intermediate tray (15) by a predetermined distance by a conveyance means (16) based on the sheet size information stored in the storage means (50). clamping, then refeeding means (
16), the first and second driving means (Ml, M2, M3) are controlled to refeed one sheet at a time.

(F) Examples Examples of the present invention will be described below with reference to the drawings.

Note that the same parts as those described above are given the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, the copying machine 1 is equipped with two cassettes 30 and 31 inside the machine body 2, the cassette 30 is attached with a feeding roller 32, and the cassette 31 is equipped with a feeding roller 32. A paper feed roller 33 is attached. A separation section 35 consisting of a conveyance roller and a separation roller is disposed downstream of the paper feed roller 32, and a separation section 35 consisting of a conveyance roller and a separation roller is disposed downstream of the paper feed roller 33. 36 are disposed, and a pair of conveying rollers 37 is disposed downstream of these separating portions 35 and 36. Further, the machine body 2 is provided with a manual feed tray 39, and a paper feed roller 40 is attached to the tray 39. Further, on the downstream side of the roller 40, a separating section 41 consisting of a conveying roller and a separating roller is arranged, and on the downstream side of the separating section 41, a manual feeder that communicates with the upstream side of the pair of registration rollers 6 is provided. A route 42 is provided. The copying machine 1 also includes a sheet end sensor 46 facing the flapper 10 and consisting of a detection lever 43 and an optical sensor 45. In the figure, 47 is a pair of transport rollers whose drive can be controlled, and 48 is a transport roller.

In addition, the upper and lower rollers 20a of the refeed roller pair 2o,
20b are adapted to be driven separately.

On the other hand, the copying machine 1 includes a control section 49, as shown in FIG. 2, and the control section 49 includes a storage section 50 consisting of a ROM and a RAM. A sheet end sensor 46 is connected to the input section of the control section 49, and the output section includes a motor M1 that drives the transport roller pair 16, a motor M2 that drives the upper roller 20b of the refeed roller pair 20, A motor M3 etc. that drive the lower roller is connected, and a timer T is further connected to the input/output section.

Next, the operation of this embodiment will be explained along the flowcharts shown in FIGS. 3 to 6.

When manual paper feeding and screen copying are selected using an operation unit (not shown) and a start key (not shown) is pressed, the paper feeding roller 40 starts rotating and feeds the sheet S from the manual feeding tray 39 to the separation unit 41. , the sheets S are separated one by one by the separating section 41 and conveyed to the pair of registration rollers 6. Then, the sheet S is conveyed by a pair of registration rollers 6 in synchronization with the image on the photosensitive drum 21, and the image on the photosensitive drum 21 is transferred by a transfer charger 25. Then, the sheet S is conveyed to the fixing device 9, and the sheet S is transported to the fixing device 9.
The image is fixed. Furthermore, the sheet S is conveyed to the flapper 10 by the conveyance roller 48, and
0, the paper is guided to a pair of paper discharge rollers 11. At this time, the control unit 49 determines whether or not there is a sheet S based on the signal from the sheet end sensor 46, that is, whether the sensor 46 detects the sheet S
81), and if it is determined that there is a sheet S, the timer T is set to 1 equal to the process speed and the timer T is started (82). For example, the process speed is set to 1. and start.

Note that the control unit 49 counts every clock of the timer T. Then, the sheet S guided to the paper ejection roller pair 11 is conveyed to the outside of the machine body 2 by the roller pair 11, and the sheet edge sensor 46 detects that the trailing edge of the sheet S has passed the flapper 10. In other words, when the sensor 46 no longer detects the sheet S (S3), the control unit 49 stops the timer T and sets the counted value (X,)
That is, the length of the sheet S is stored in the storage unit 50 (84), and the paper ejection roller pair 11 is reversed. Then, the sheet S is conveyed to the re-conveying path 12 through the reversing path 12a, and is then held between the pair of conveying rollers 13 and conveyed to the pair of conveying rollers 16 (see FIG. 7(a)). The unit 49 rotates the upper and lower rollers 20a and 20b of the transport roller pair 16 and the paper refeed roller pair 20 in the normal direction 35) (Fig.
(see I2.b)), a distance sufficient for the trailing edge of the sheet S to pass through the pair of conveying rollers 13 and fall onto the intermediate tray 15, i.e., I2. -x.

+β is transported (S6) (see FIG. 7(b)).

Note that β is the distance from the end of the guide plate forming the re-conveying path on the downstream side of the conveying roller pair 13 to the conveying roller pair 16, and β is the amount of displacement of the leading edge of the sheet (see FIGS. 8 and 9). ), and the control unit 49 controls the transport roller pair 16
Then, the upper and lower rollers 20a and 20b are reversely rotated 57) (see FIG. 7(e)), and the sheet S is moved upstream by β, -xn (S8), and the movement of the sheet S is completed. Then, the control unit 49 stops the transport roller pair 16 and the upper and lower rollers 20a, 20b and locks them so that they do not rotate (S9).As a result, the sheet S has its leading end protruding from the transport roller pair 16 by the β length. The roller pair 1
6 (see FIG. 7(d)). Then, the control unit 49 determines whether or not the desired number of sheets S has been stacked on the intermediate tray 15 (5IO), and performs the operations from S5 onwards until the desired number of sheets S is stacked on the tray 15 (5IO).
(See Figures 7(e) to (h)). As a result, a desired number of sheets S are placed on the intermediate tray 15 with their leading edges separated by a predetermined distance (I
2) When the sheets S are stacked in a staggered manner (see FIG. 10) and then re-fed from the intermediate tray 15, the control unit 49 controls the upper and lower rollers of the transport roller pair 16 and the re-feed roller 20. Rotate 20a and 20b forward (Sll) (first
(See Figure 1(a)). As a result, the sheet S remains overlapped by the pair of transport rollers 16 and 47 and is transferred to the pair of refeed rollers 2.
0 by a predetermined distance 122-n12+1 (812), where n is the number of sheets S to be stacked. Then, the control unit 49 stops the transport roller pair 16 and the upper and lower rollers 20a and 20b (S13), so that the lowest and foremost sheet S is transferred to the refeed roller pair 20a, 20b.
Further, the control unit 49 makes the pair of conveying rollers 16 free to rotate, and the upper roller 20
a to the locked state, and further rotate the lower roller 20b in the normal direction (314) (see FIG. 11(c)). As a result, the lowest sheet S is re-fed by the lower roller 20b by a predetermined distance (x, -12) toward the pair of registration rollers 6 (315) (see FIG. 11(a)), and then Part 4
9 sets the lower roller 2ob in a free state 516), whereby the sheet S is copied a second time on the blank surface by the same operation as described above, and is ejected from the machine body 2. Then, the control unit 49 determines whether or not the sheet feeding is completed (517), and if it is determined that it has been completed, it rotates the pair of conveying rollers 16 and the upper and lower rollers 20a, 20b in the normal direction (818), leaving the sheets S superimposed. After conveying by β, the conveyance roller pair 16 and the upper and lower rollers 20a, 20b are stopped (S19) (see FIG. 11(e)).Then, the control unit 49 determines whether or not a predetermined number of sheets have been fed. 820), and if it is determined that the predetermined number of sheets have been fed, the operation ends.

Also, if it is determined that the specified number of sheets are not being fed,
The control unit 49 determines whether it is the paper feeding timing (321).
, if it is determined that it is the paper feeding timing, the operations after 814 described above are performed.

In addition, when performing multiple copying three or more times, 1. In the same manner as described above, the leading edges of the sheets S are stacked on the intermediate tray 15 by shifting them by a predetermined distance, and after refeeding the lowest and first sheet S as described above, the other sheets S are stacked on top of each other and are moved toward the upstream side. The upper sheet S is returned to the position where it protrudes by an amount a from the pair of transport rollers 16 (see FIG. 13), and the re-fed sheet S is copied a second time by the same operation as described above, and transferred to the intermediate tray. The sheet S is stacked again on top of the sheets S stacked on No. 15. Thereafter, by the same operation, 1 from the predetermined number of times.
The sheets S that have been copied a few times and stacked on the intermediate tray 15 are sequentially re-fed starting from the lowest sheet S by the same operation as described above, are copied a predetermined number of times, and are then removed from the machine 2. is discharged to.

In the above embodiment, two pairs of conveyance rollers 16.47 are arranged on the intermediate tray 15, but the present invention is not limited to the number of conveyance roller pairs.

Further, in the above-described embodiments, a copying machine is used as the image forming apparatus, but the present invention is not limited to this and can be applied to any image forming apparatus such as a laser beam printer or a facsimile.

(G) As described in detail, according to the present invention, the first drive means and the second drive means are controlled based on the sheet size information detected by the detection means and stored in the storage means. With this configuration, the size of the sheet can be detected on the upstream side of the intermediate tray, and double-sided or multiple image formation can be performed on a sheet of unknown size, such as a manually fed sheet.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an image forming apparatus according to the invention, and FIG. 2 is a block diagram showing a control means according to the invention. Further, FIGS. 3 to 6 are flowcharts showing the operation of the present invention. Furthermore, FIGS. 7 to 13 are diagrams showing the operation of the present invention. FIG. 14 is a front sectional view showing a conventional example. 1.1a... Image forming device 12... Re-conveying path 15... Intermediate sheet storage device 16... Conveying means 20... Re-feeding means 46... Detecting means
49...Control means 50...Storage means Ml
...first driving means, M2. M3...Second driving means S...Seat

Claims (1)

[Scope of Claims] 1. A re-conveyance path for re-conveying sheets on which images have been formed to form double-sided or multiple images, an intermediate sheet storage device disposed in the re-conveyance path, and the intermediate sheet storage device a conveyance means that shifts the leading edge of the sheets stacked on the sheet by a predetermined distance and pinches them; a first drive means that drives the conveyance means; and a refeeder that refeeds the sheets held by the conveyance means one by one. and a second driving means for driving the refeeding means, wherein the size of the sheets arranged along the sheet conveyance path on the upstream side in the sheet conveyance direction of the intermediate sheet storage device a detection means for detecting sheet size information detected by the detection means; and a storage means for storing sheet size information detected by the detection means; based on the sheet size information stored in the storage means, sheets of various sizes to be conveyed to the intermediate tray are control means for controlling the first and second driving means so that the leading end of the sheet is shifted by a predetermined distance and held by the means, and the sheet is re-fed one by one by the re-feeding means; image forming apparatus.