JPH03253866A - Form inverting device - Google Patents

Abstract

PURPOSE:To enable form inversion matching print timing by make forms pass by each other at the time of the inversion and carrying one form while carrying the other onto an inversion table, and holding the form at the time of the inversion according to the form size and adjusting the timing. CONSTITUTION:A setting means 17b sets the inversion timing of each form size with the output of a form size detecting means 17a and a driving means 17 drives a paper feed roller 13, a return roller 14, and a plural-form feeding preventive roller 16 at the timing set for forms of A4, B4, and A3 sizes. The forms pass by each other when inverted and are carried out of the inversion table while carried onto the inversion table, and the forms are held temporarily according to the form sizes when inverted, so that the timing can be adjusted. Consequently, intervals of forms can be shortened and the idle time becomes short; even if the number of sheets of paper varies according to the size of the form, the form can be inverted according to the print timing of a copying machine main body.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a paper reversing device for reversing a sheet for double-sided printing in a copying machine, a laser printer, or the like.

<Prior Art> In a conventional printing device such as a copying machine capable of double-sided printing, a sheet of paper printed on one side is conveyed to a paper reversing device, and the sheet is reversed and returned to the main body of the copying machine at a constant speed.

Then, the registration rollers print on the opposite side of the paper in accordance with the printing timing of the copying machine main body, and the paper is ejected.

As shown in FIG. 12(a), the paper reversing device includes a reversing table 60 that changes the direction of the sheet and reversing it, and a transport roller that transports the paper 61a from the copying machine main body to the reversing table 60 along a transport path 62. G3a, 63b and the paper 61a on the inversion table 6
Paper feed roller 6 that is carried into 0 or carried out from the reversing table 60
4a, 64b, and return conveyance rollers 66a, 66b that return the paper 61a to the copying machine main body along the conveyance path 65. One is driven and the other is driven.

Here, the paper reversing operation is first shown in FIG. 12(a).

As shown in (b), the paper 61a is transported by the transport rollers 63a,
b and paper feed rollers 64a and 64b, the paper is transported to the reversing table 60. In Figures (c) and (d), while the paper 61a is being carried in, the next paper 61b is being conveyed from the main body of the copying machine. At this time, the distance between the sheets is as follows.

L=J+k Q: Length of paper: Distance traveled during the reversal time of the paper required when switching the conveyance path (e), (r), (g)
The direction of rotation of the paper 61a is switched, and the paper 61a is carried out from the reversing table 60 to the return conveyance path 65. In the same figure (h), paper 6
When the sheet 1a is completely unloaded from the reversing table 60 and the reversing is completed, the rotation direction of the paper feed rollers 64a, 64b is switched again, and immediately the next sheet 61b starts to be conveyed to the reversing table 60.

<Problem to be Solved by the Invention> However, in a copying machine, the printing speed changes depending on the paper size and the number of sheets processed changes, but the paper reversing device reverses each sheet one by one at a constant speed. It will take a long time. Therefore, when making double-sided copies, the copying machine must perform its own double-sided printing process that is compatible with the paper reversing device, resulting in the problem that the copying machine's full printing processing capabilities cannot be utilized. be.

In view of the above, an object of the present invention is to provide a paper reversing device capable of reversing a sheet in synchronization with the printing timing of a printing device regardless of the paper size.

<Means for Solving the Problems> The means for solving the problems according to the present invention are as shown in FIGS. 1 to 4,
A paper feed roller 13 that feeds the paper 3 printed on one side and conveyed from the printer main body l to the reversing table I2, and the paper feed roller 1
3, and a double-feed prevention roller I6 that prevents double-feeding of the paper 3 in the return conveyance path 15 from the paper reversing device main body IO to the printing device main body 1,
The paper feed roller 13, return roller I4, and double feed prevention roller 16 are driven in synchronization with the printing timing of the printing device main body l according to the paper size. The control unit I7 includes a paper size detection means 17a for detecting the paper size, and a setting means for setting the reversal timing in synchronization with the print timing according to the paper size.
7b, and a driving means 17c for driving the paper feed roller 13, return roller 14, and double feed prevention roller 16 by the output from the setting means 17b.

<Operation> In the two-leg problem solving means, the paper size detection means 17
Based on the output from a, the setting means 17b sets the reversal timing for each paper size. Then, according to this reversal timing, the driving means 17 moves A4°B4. For each A3 size paper 3, the paper feed roller I3 is activated at the set timing.
, drives the return roller 14 and the double-feed prevention roller I6.

That is, a sheet 3a with one-sided printing printed on one side is fed from the copying machine main body 1 to the reversing table I2 by the sheet feeding roller I3, and the next sheet 3b is conveyed to the front of the reversing table 12.

Then, the paper feed roller 13 is stopped, the return roller 14 is driven, and the paper 3a is sent out to the return conveyance path I5. Then, the next sheet 3b that has been conveyed is sent to the reversing table I2 by the sheet feeding roller 13. At this time, the return roller I4 is stopped, and the paper 3a is transported through the return transport path 15 by the drive of the double-feed prevention roller I6, but the paper 3a
The rear end still remains in the reversing table 12, and while the two sheets of paper are shifted, the sheets are fed to the reversing table 12 and returned from the reversing table 12 to the copying machine main body l at the same time.

Further, the next sheet 3c is fed from the copying machine main body l to the reversing table 12, and the interval between these sheets is equal to the distance Mk traveled during the sheet reversing time required when switching the conveyance path (L =k) Anything is fine.

Therefore, in the paper reversing device of the present invention, the sheets can be carried into the reversing table and taken out from the reversing table at the same time by allowing the sheets to pass each other during reversing, and depending on the paper size, the sheets are temporarily put on standby during reversing to adjust the timing. This makes it possible to shorten the distance between sheets of paper and reduce idle time.

Moreover, even if the number of sheets processed changes depending on the paper size,
Since the paper can be reversed in accordance with the printing timing of the copying machine itself, you can make full use of the copying machine's capabilities.

<Embodiment> Hereinafter, an embodiment in which the present invention is applied to a copying machine as a printing device will be described based on the drawings.

FIG. 1 is a schematic diagram of a paper reversing device used in a copying machine showing an embodiment of the present invention, FIG. 2 is a control block diagram of the paper reversing device, and FIG. 3 is a perspective view of a paper feed roller and a return roller. Figure 4 is a perspective view of the electric transmission prevention roller, Figures 5 (a) to (f)
is a diagram showing the operation when paper is reversed, Fig. 6 is a timing chart when printing on both sides of A4 paper, Fig. 7 is a timing chart when printing on both sides of B4 paper, and Fig. 8 is a timing chart when printing on both sides of A4 paper.
3 Timing chart when printing on both sides of paper, No. 9
The figure is a diagram showing the time course of paper conveyance in the present invention.
FIGS. 0 and 11 are diagrams showing the time course of paper conveyance in the prior art.

[Schematic structure of copying machine] As shown in Fig. 1, the copying machine capable of double-sided printing of this embodiment has a photoreceptor 2 rotatably disposed in a copying machine body 1, and a paper 3 is fed to the photoreceptor 2. A paper feed section 4 , a registration roller 5 that temporarily waits for the paper 3 sent from the paper feed section 4 and conveys the paper 3 in accordance with the rotation of the photoreceptor 2 , and transfers the toner image from the photoreceptor 2 onto the paper 3 a transfer unit 6 that transfers the transferred paper 3 to a fixing roller 7, a conveyor belt 8 that sends the transferred paper 3 to a fixing roller 7, and a conveyor belt 8 that transports the transferred paper 3 to a fixing roller 7;
A paper reversing device main body 10 is provided at the lower part of the copying machine main body 1. Further, a paper detection switch 11 for detecting passage of the paper 3 is disposed on the front side of the registration roller 5 in the paper traveling direction.

[Schematic configuration of paper reversing device] The paper reversing device main body lO includes a paper feed roller I3 that feeds the paper 3 printed on one side and conveyed from the copying machine main body l to the reversing table 12, and a paper feed roller I3 in the opposite direction to the paper feed roller 13. The return roller 14 rotates to
The paper feeding roller I3, the return roller 14, and the double feeding prevention roller 16 are arranged in the printer main body 1 according to the paper size. The paper feed roller 13, return roller 14 and double feed prevention roller 16 are activated in synchronization with the printing timing of
A control section 17 is provided to drive the.

The control section 17 includes a paper size detection means 17a that detects the paper size, and a setting means 17 that sets the reversal timing in synchronization with the printing timing according to the paper size.
b, and a drive means +7c for driving the paper feed roller 13, return roller 14, and double feed prevention roller 16 by the output from the setting means 17b.

The details of each of the above components will be explained below.

[Components forming a part of the copying machine] The paper feed section 4 includes a cassette 4a containing paper 3, and a cassette 4a that feeds the paper 3 from the cassette 4a to the main body of the copying machine! It consists of a paper feed roller 4b that feeds paper inside.

A branch path 19 is formed between the fixing roller 7 and the paper ejection roller 9 for conveying the paper 3 to the paper reversing device main body 10 when double-sided copying is performed, and the conveyance path is switched to the branch path 19. A switching lever 20 is provided for this purpose.

[Transport path of paper reversing device] A transport path 21 from the branch path I9 to the reversing table 12 is formed on the paper reversing device main body IO side, and a pair of transport paths 21 for transporting the paper 3 to the reversing table 12 are formed on the transport path 2I. First and second conveyance rollers 22a22b are arranged.

Then, the first conveyance roller 22a and the second conveyance roller 22b
A paper length detection switch 23 for detecting the leading and trailing ends of the paper 3 passing through is arranged between the paper length detection switch 23 and the paper length detection switch 23 .

[Reversing Table The reversing table I2 is formed at the tip of the conveying path 21 and temporarily places the paper 3 conveyed by the conveying rollers 22a and 22b. A stopper 24 that comes into contact with the leading edge of the paper 3 to stop the advance of the paper 3 is fixed to the stopper 24.
can be moved according to the paper size, and a detection switch 25 for detecting the presence or absence of the paper 3 on the reversing table 12 is disposed in front of the stopper 24.

"Paper feed roller and return roller" The paper feed roller 13 is a paper feed roller rotatably supported by the paper reversing device main body 10 between the second conveyance roller 22b and the reversing table 12, as shown in FIG. These are a pair of left and right cylindrical rollers that are externally fitted onto the shaft 26.When a torque of a certain level or more is applied to the paper feed roller 13, the paper feed roller 1
Torque limiter 2 for cutting off torque transmission to 3
7, and the return roller 14 is disposed above and opposite to the paper feed roller 13.

The return roller 14 is formed into a horseshoe shape and is externally fixed to a return roller shaft 28 that is rotatably supported by the paper reversing device main body IO. Then, the arc portion 14 of the return roller 14
A has a high coefficient of friction so that it is easy to send out the paper 3 from the reversing table 12, and an arc portion 14b has a low coefficient of friction so that the paper 3 is fed to the reversing table 12 by the paper feed roller I3. When this happens, it is made so that there is no resistance. Further, a pair of discs 29 are loosely fitted on the return roller shaft 28 in the vicinity of the return roller 14, and the discs 29 contact the paper feed roller 13 to prevent the paper 3 from entering the reversing table 12. It's easy.

One ends of the paper feed roller shaft 26 and the return roller shaft 28 are mounted on bearings 30a, 30 fixed to the paper reversing device main body 10.
A first gear 32 is rotatably inserted into the feed roller shaft 26 and meshes with a drive gear 31 connected to a drive motor (not shown) at the other end of the paper feed roller shaft 26.

Further, a clutch 33 for stopping the rotation of the paper feed roller I3, and a one-way clutch 34 for preventing the paper feed roller shaft 26 from reversing when the return roller I4 is activated while the paper feed roller I3 is stopped. installed.

A second gear 35 that meshes with the drive gear 31 and a clutch 36 for stopping the rotation of the return roller 14 are attached to the other end of the return roller shaft 28 .
is rotatably supported by the sheet reversing device main body 10.

[Return Conveyance Path] The return conveyance path 15 is a path leading from the reversing table 12 to the registration rollers 5, and includes the double feed prevention roller I6 and first, second, and third return conveyance rollers 38a38b, 38c. ing. Further, the upper roller of the second conveyance roller 22b also has a function of conveying the paper 3 to the return conveyance path 15.

[Double Feed Prevention Roller] The double feed prevention roller 16, as shown in FIG. The side gluing roller 16a is equipped with a torque limiter 41.

One ends of the lower roller shaft 39 and the upper roller shaft 40 are rotatably inserted into bearings 42a and 42b fixed to the sheet reversing device main body 10, and a double-feed prevention roller drive motor is connected to the other end of the upper roller shaft 40. (not shown), a gear 44 integrated with the drive gear 43, and a clutch 45 for stopping the rotation of the retard roller 16b are attached. It is rotatably supported by the paper reversing device main body 10 by 46a. Further, a driven gear 48 is attached to the other end of the lower roller shaft 39 and meshes with a transmission gear 47 that meshes with a gear 44 of an upper roller shaft 40, and is rotatably supported by the paper reversing device main body 10 by a bearing 46b. ing.

The first, second and third return conveyance rollers 38a, 38
b and 38c are simultaneously stopped from rotating by a return conveyance roller clutch (not shown) attached to the first return conveyance roller 38a. Then, each return conveyance roller 38a, 3
Detection switches 49a, 49b, 49c for checking the jam and passage of paper 3 are located on the front side of paper 3 in the paper advancing direction of 8b, 38c.
are arranged.

[Control Unit] The control unit j7 is a general one-chip microcomputer, and includes a CPU, a ROM in which print timing for each paper size is programmed, and a RAM. The input side is connected to a paper selection switch 50 on the copying machine main body l or a document size detection sensor 51 for detecting the paper size, and a paper detection switch 11 on the front side of the registration roller 5 for paper conveyance. , and a paper length detection switch 23 in the transport path 21 are connected.

On the output side of the control unit 17, a registration roller 5 and first and second conveyance rollers 22a, 22b, which are activated after a certain period of time has passed when the paper detection switch 11 is turned on, and a paper feeder, which is activated when the paper length detection switch 23 is turned on. A roller 13, a return roller 14 that operates only once after a certain period of time has passed after the output of the paper length detection switch 23 is turned off, and a double-feed prevention roller 16 that operates for the length of one sheet of paper, and the double-feed prevention roller. A return conveyance roller 38a operates in synchronization with I6.

38b and 38c are connected.

The paper size detection means 17a includes a paper selection switch 5.
It has a function of determining the size of paper to be printed on based on the output from 0, etc.

The setting means 17b performs the driving according to a sheet reversing program for each sheet size stored in the ROM in advance in synchronization with the printing timing of the copying machine main body l, for the sheet size determined by the sheet size detecting means 17a. It has a function of activating the means 17c.

The driving means 17c operates the registration roller 5 and the first and second conveyance rollers 22 when the paper detection switch 11 is turned on.
a, 22b and stops the registration roller 5 after a certain period of time after the paper detection switch 11 is turned off, a function that drives the paper feed roller 13 when the paper length detection switch 23 is turned on, and a paper length detection switch 23. is turned off to stop the paper feed roller 13 after a certain period of time has elapsed, and after a certain period of time has elapsed, the return roller 14 and double feed prevention roller 16 are driven, and then the return conveyance rollers 38a, 38b, 38
It has the function of driving c.

These drive timings are executed by counting the time set for each paper size by the setting means +7b based on a timer.

[Operation] In the above configuration, the operation of the paper feed roller 13 and the return roller 14 when the paper 3 is reversed will be explained based on FIG. 5.

First, the setting means 17b sets the reversal timing for each paper size based on the output from the paper size detection means 17a. Then, according to this reversal timing, the driving means 17 drives the paper feed roller 13, the return roller 14, and the double-feed prevention roller 16 at the set timing for the paper 3 of each paper size.

In other words, as shown in FIG.
2i sheets have been fed, and the next sheet 3b is already being conveyed through the conveyance path 21 by the conveyance rollers 22a and 22b.

In (b) and (c) of the same figure, since the paper 3a has passed the paper length detection switch 23, the switch 23 is turned off, the drive of the paper feed roller 13 is stopped, the return roller 14 is driven, and the paper 3a is turned off. is sent out to the return conveyance path 15.

At this time, since the paper feed roller 13 has a one-way clutch 34, the paper feed roller I3 rotates as the return roller 14 rotates, but this rotation is not transmitted to the drive gear 31 of the paper feed roller shaft 26. .

In FIG. 3D, the next sheet 3b that has been conveyed turns on the sheet length detection switch 23, so that the sheet feed roller I3 is driven. At this time, the return roller 14 is stopped;
The paper 3a is conveyed through the return conveyance path 15 by the drive of the double-feed prevention roller 16.

In Figures (e) and (f), the trailing edge of the sheet 3a still remains in the reversing table I2, but the leading edge of the next sheet 3b is fed into the reversing table 12 by the drive of the paper feed roller I3. Ori, 2
While the sheets of paper pass each other, the sheets are simultaneously fed to the reversing table 12 and returned from the reversing table 12 to the copying machine main body l.

At this time, the next sheet 3c is fed from the copying machine main body l to the reversing table I2, and this interval is equal to the distance k traveled during the sheet reversing time required when switching the conveyance path (L= k).

[Operation for A4 Paper] Next, the operation of the paper reversing device for each paper size will be explained. The rollers are activated.

That is, for A4 paper 3, the paper size is determined by the paper size detection means 17a based on the output of the paper selection switch 50, and the printing timing for A4 size is set by the setting means 17b.

Then, as shown in Fig. 6, 1°5 se from the copying machine body 1.
A print signal is output at intervals c. This output drives the paper feed roller 4b, and the paper 3 is fed from the paper feed cassette 4a.
is called. Then, after the paper feed roller 4b is temporarily stopped, it is driven again and the paper 3 is transferred to the paper detection switch I+.
The leading edge of the paper 3 is pressed against the resisting rollers 5 and forms a loop, reducing the variation in the leading edge.

Then, after a certain period of time has passed after the paper detection switch 11 is turned on, the registration rollers 5 and the transport rollers 22a, 2
2b rotates and the paper 3 is conveyed to the photoreceptor 2, where it is transferred, fixed, and printed on the surface. At this time, the next sheet 3 is being fed in the same way. The printed paper 3 is
The paper is sent to the transport path 21 by the switching lever 20, passes through the first transport roller 22a, and passes the paper length detection switch 23.

Then, the drive motor of the paper feed roller 13 is driven, the drive gear 31 is rotated, and the first gear 32 and the second gear 35 are rotated.

At the same time as the paper length detection switch 23 is turned on, the clutch 33 of the paper feed roller shaft 26 is turned on, but the clutch 36 of the return roller shaft 28 remains off.
only rotates. Then, the paper 3 is sent to the reversing table 12 by the paper feed roller 13. At this time, the third sheet 3 is conveyed to the photoreceptor 2 by the registration rollers 5.

After the paper 3 passes the paper length detection switch 23 and a certain period of time has elapsed, the paper feed roller 13 stops, and at the same time, the clutch 36 of the return roller 14 is turned on and the return roller I4 rotates, and at the same time, the electric transfer prevention roller 4 is also turned on. rotated, paper 3
is sent back from the reversing table 12 to the conveyance path I5. and,
The return roller 14 is set to 1 when the paper length detection switch 23 is turned off.
After a certain period of time has elapsed, the return conveyance rollers 38a, 38b, and 38c rotate to convey the paper 3 to the front of the registration roller 5. At this time, the third sheet 3 has already passed through the registration rollers 5 and is conveyed to the photoreceptor 2.

When the paper 3 transported from the reversing table 12 for printing on the back side passes through the paper detection switch 11 and is turned on, it is immediately returned to the transport rollers 38a and 38b.

38c is stopped. After the paper 3 is temporarily stopped by the registration roller 5 for a certain period of time to match the rotation of the photoconductor 2, the registration roller 5 rotates and conveys the paper 3 to the photoconductor 2, the back side is printed, and after transfer and fixing. , and is discharged to the outside of the copying machine main body l by the paper discharge roller 9. Subsequently, the second and third sheets 3 are printed on both sides and are discharged one after another.

In this way, while the surface of the first sheet 3 is being printed and being conveyed to the sheet reversing device main body 10, the second sheet 3 is
The surface of the image is printed. While the first sheet 3 is being conveyed from the paper reversing device main body IO to the copying machine main body 1, and the second sheet 3 is being conveyed to the paper reversing device main body IO, the surface of the third sheet 3 is It will be printed. When the back side of the first sheet 3 is being printed, the second sheet 3 is conveyed to the copying machine main body 1, and the third sheet 3 is transported to the paper reversing device main body I.
Transported to O. While the back side of the second sheet 3 is being printed, the third sheet 3 is conveyed to the copying machine main body l.

[Operation for B4 paper] Furthermore, for B4 paper 3, as shown in FIG. 7, when the paper size detection means 17a determines that the paper size is B4,
The printing timing for B4 size is set by the setting means 17b.

That is, when a print signal is output from the copying machine main body 1 at an interval of 2.3 seconds, the paper feed roller 4b rotates for a certain period of time. When the paper 3 is fed from the paper cassette 4a and the paper detection switch 11 is turned on, the paper feed roller 4b stops, the paper 3 is pressed against the registration roller 5, forms a loop, and stops at -. . Then, after a certain period of time has passed after the paper detection switch 11 is turned on, the registration roller 5, the paper feed roller 4b, and the transport rollers 22a, 22
b rotates at the same time.

As soon as the paper 3 passes the paper detection switch 11 and is turned off, the registration roller 5 is stopped.

The paper 3, which has been conveyed to the photoreceptor 2 and whose surface has been printed, is transported to the conveyance path 2.
1, and the paper length detection switch 23 is turned on, at the same time the paper feed roller 13 rotates.

At this time, the second sheet 3 is fed, the sheet detection switch 11 is turned on, the registration rollers 5 are rotated, and the second sheet 3 is conveyed to the photoreceptor 2 and surface printing is performed.

On the other hand, the first sheet 3 carried into the reversing table 12 is kept on standby for a while on the reversing table 12. During this time, the third sheet of paper 3 is fed, is conveyed to the photoreceptor 2 by the registration roller 5, and is printed on its surface, and the second sheet of paper 3 passes through the conveyance path 21 and turns on the paper length detection switch 23. . Then, the paper feed roller 13 rotates, and the second sheet 3 is carried into the reversing table 12.

At this time, the first sheet of paper 3 is detected by the paper length detection switch 23.
When a certain period of time has elapsed after passing through and turning off, the return roller 14 and the double-feed prevention roller 16 rotate. Since the paper feed roller 13 and the return roller 14 are rotating in the same direction, the second sheet 3 is transported into the reversing table 12 by the paper feed roller 13, and the second sheet 3 is transported to the reversing table 12.
The second sheet of paper 3 is carried out from the reversing table 12 by the return roller 14 while passing by the second sheet of paper 3, and is transported to the return conveyance path 15.
sent to.

The return roller 14 rotates once and takes out the first sheet 3 from the reversing table 12, and then stops. At this time, since the third sheet 3 is being conveyed to the photoconductor 2 by the registration rollers 5, the electric transfer prevention roller 1
6 is temporarily stopped, and the paper 3 is temporarily put on standby in the return conveyance path 15.

After a certain period of time has elapsed, the double-feed prevention roller 6 rotates again, and at the same time, the return conveyance rollers 38a, 38b, and 38c also rotate to convey the paper 3 to the registration roller 5, where it is temporarily put on standby. During this time, the second sheet 3 is on standby within the reversing table 12.

Then, when the third sheet 3 is conveyed through the conveyance path 21 whose surface is printed and passes through the sheet length detection switch 23, the sheet feed roller 13 rotates and conveys the sheet 3 to the reversing table 12. 2
When a certain period of time has elapsed since the first sheet of paper 3 passed through the paper length detection switch 23 and was turned off, the return roller 14 rotates to transfer the second sheet of paper 3 to the third sheet of paper 3 in the same manner as described above.
It passes by and is carried out from the inversion table 12. At this time, 1
The back side of the sheet 3 is printed and then discharged to the outside of the copying machine main body 1. Then, the second and third sheets 3 are similarly printed on both sides and then discharged.

[Operation for A3 paper] Furthermore, as shown in Fig. 8, for A3 paper 3, a print signal is output from the copying machine body 1 at an interval of 2.725 seconds, and the inversion table is output at the same timing as for A4 paper 3. Transported to +2. Then, when the paper 3 is carried into the reversing table 12 and the paper feed roller 13 stops, the return roller 14 and double feed prevention roller 16 rotate at the same time, and the paper 3 is transferred to the reversing table 12.
sent from. When the return roller 14 rotates once and stops, the double-feed prevention roller 16 also stops, and the paper 3 is temporarily put on standby. At this time, the second sheet 3 is being conveyed to the photoreceptor 2 by the registration rollers 5.

Then, the paper 3 that was waiting at - time is transferred to the double feed prevention roller 1.
6 and the return conveyance rollers 38a, 38b, and 38C are rotated to convey it to the registration roller 5, and -
After being put on standby for a while, it is transported to the photoreceptor 2 and printed on the back side.

Here, FIG. 9 shows the time course of paper conveyance for each paper size. Note that FIG. 10.11 shows the passage of time in a conventional sheet reversing device for comparison with the present invention. The relationship between these times and printing speed is shown in Tables 1-
Shown in Table 3. Table 1 is for the present invention, and Table 2.3 is for the conventional case. At this time, the specifications of the copying machine are such that the paper feed speed is 2.
The printing speed is 60 mm/sec, and the printing speed for each paper size is as shown in Table 4.

(2) Reversing device return speed is 500mm/5ee (3) Minimum idle time of paper reversing device is 0.65 secondsTable 1
(This invention).

A4 3 sheets, A4R 3 sheets B4 3 sheets, A3 2 sheets Note (1) It is assumed that one sheet of paper can enter the conveyance path.

However, consider that A4 size can hold two sheets.

(2) Reversing device return speed is 260m/5ec (3) Allowance time ty = 2.08- ((Tr/ 2-2.3-
twr) 10 Tsb) (4) The minimum idle time of the paper reversing device is 0.7 sec.
Table 4 (Copier specifications) Table 3 (Conventional) Notes (1) Assuming that one sheet of paper can fit in the conveyance path.

However, consider that A4 can hold two sheets of paper.

(2) The reversing device return speed is 500mm/5ec (3) Allowance time Ty = 1.08-((Tr/2-2.31tw
r)-t-Tsb)+2.3l-Tc However, the synchronization time is the processing time per side of the paper, the rotation time is the time required for the paper to go around from the registration roller to the registration roller via the reversing device, and the idle time is the synchronization time. It is the time obtained by subtracting the reversal time from

From the above results, the paper reversing device of the present invention can pass the sheets of paper during reversal, carry the paper into the reversing table, and take it out from the reversing table at the same time, and depending on the paper size, the paper is temporarily on standby during reversing. Since the distance between the sheets can be adjusted, the distance between sheets can be shortened, and idle time can be reduced. In contrast, with conventional machines, the paper must be reversed one by one, so the timing cannot be adjusted when reversing, and the printing speed etc. must be adjusted on the copying machine itself, making it difficult to process double-sided printing. The speed will become slower.

Therefore, even if the number of sheets to be processed changes depending on the paper size, the paper can be reversed in accordance with the printing timing of the copying machine main body, so that the copying machine can make full use of its capabilities.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in this 3M, a stopper is provided on the inversion table 12 (the paper 3 is retained on the inversion table 12 above, but the paper 3 may be inverted one by one without providing a stopper.

Further, the paper reversing device of the present invention may be applied not only to copying machines but also to printers.

<Effects of the Invention> As is clear from the above description, according to the present invention, there is a paper feed roller that feeds the paper that has been printed on one side and is conveyed from the printer main body to the reversing table, and a paper feed roller that rotates in the opposite direction to the paper feed roller. and a double-feed prevention roller that prevents double-feeding of paper in the return conveyance path from the paper reversing device main body to the printing device main body, and the paper feed roller, return roller, and double-feed prevention roller A control unit (3) is provided to drive the paper feed roller, return roller, and double feed prevention roller in synchronization with the printing timing of the printer main body in accordance with the printing timing. and a setting means for setting a reversal timing synchronized with the printing timing according to the paper size, and a driving means for driving the paper feed roller, return roller, and double feed prevention roller by the output from the setting means. , it is possible to pass the paper during reversing and carry it into the reversing table and take it out from the reversing table at the same time.
Since the timing can be adjusted by temporarily holding the paper during reversal according to the paper size, it is possible to shorten the interval between the paper and reduce the idle time.

Therefore, even if the number of sheets to be processed changes depending on the paper size, the paper can be reversed to match the printing timing of the copying machine itself, making it possible to utilize 100% of the capabilities of the copying machine. It has a positive effect.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a paper reversing device used in a copying machine showing an embodiment of the present invention, FIG. 2 is a control block diagram of the paper reversing device, and FIG. 3 is a perspective view of a paper feed roller and a return roller. ,
Figure 4 is a perspective view of the electric transmission prevention roller, and Figures 5 (a) to (f).
) is a diagram showing the operation when paper is reversed, Figure 6 is a timing chart when printing on both sides of A4 paper, Figure 7 is a timing chart when printing on both sides of B4 paper, and Figure 8 (
Timing chart when printing on both sides of IA3 paper,
FIG. 9 is a diagram showing the time course of paper conveyance in the present invention;
10 and 11 are diagrams showing the elapse of time during sheet conveyance in the conventional technique, and FIGS. 12(a) to 12(h) are diagrams illustrating the conventional operation when reversing the sheet. One, 172 control unit, 17a: paper size detection means, 1
7b: Setting means, 17c: Driving means.

Claims (1)

[Claims] A paper feed roller that feeds the paper that has been printed on one side and has been transported from the printing device main body to the reversing table, a return roller that rotates in the opposite direction to the paper feeding roller, and a return transport path from the paper reversing device main body to the printing device main body. a control unit that is provided with a double-feed prevention roller that prevents double-feeding of paper, and that drives the paper feed roller, return roller, and double-feed prevention roller in synchronization with the printing timing of the printer main body according to the paper size; is established,
The control section includes a paper size detection means for detecting the paper size, a setting means for setting a reversal timing synchronized with the printing timing according to the paper size, and an output from the setting means to control the paper feed roller, return roller, and the like. A paper reversing device comprising: a drive means for driving a double-feed prevention roller.