JPS5821266A - Both side recording system - Google Patents

Abstract

PURPOSE:To reduce the size of a device by providing a sheet turning over and returning means which turns over the sheet recorded on the front side and returns the same from a discharging part to between a feeding part and an image forming part. CONSTITUTION:The copying paper which is recorded on the front side is discharged to a discharging part C by a discharge roller pair 24, and is then returned through a switch-back passage 26 to the midway of a feeding line 20. The copying paper returned to the line 20 is again fed in the state of rear side up to the transfer part where the toner images on a drum 2 are transferred thereon. Here, the images are formed consecutively on the front side of n(n>=2) sheets, and the n sheets recorded with the front side are successively turned over and are returned by the above-described sheet turning over and returning means in such a way that the rear side comes to the image forming side whereby images are formed on the rear side of the n sheets recorded with the front side after the images are formed on the front side of the n sheets. Such both side recording operations on the n sheets as one block are repeatedly executed, whereby the multiple sheets are subjected to both-side recording.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a double-sided recording system for forming and recording images on both sides of a single sheet.

Conventionally, copying machines and the like that were capable of forming and recording images on both sides of a sheet were developed, for example, by the Japanese Patent Publication Publication No. 53-9.
As known from Japanese Patent No. 7843, an intermediate tray is arranged between the paper feed cassette and the paper output tray, and each sheet is fed from the paper feed section to the image forming section and images are formed and recorded on the surface of each sheet. are once stacked and stored in the intermediate tray, and after the recording on the front side is completed, the sheets after the surface recording that are stacked and stored in the intermediate tray are sent out and sent again to the image forming section, and the other side of each of the sheets is Double-sided recording is performed by forming and recording an image on the paper.

In such a device, an intermediate tray for double-sided recording must be placed between the paper feed cassette and the paper ejection tray, which increases the size of the device. In addition, electrostatic adsorption force due to corona charge during the transfer process during surface recording acts between sheets stacked in the intermediate tray after surface recording, and the sheets after surface recording are fed from the intermediate tray. When the rollers feed out the sheets one by one, there is a risk that a large number of sheets may be sent out at once. Therefore, a means is required to sufficiently eliminate static electricity from the sheets stacked and stored in the intermediate tray. Furthermore, the sheets after front side recording are once stacked and stored in an intermediate tray, and then sent out one by one from either the upper or lower side and used for the next recording on the remaining back side. Sequence control becomes complicated, and loss time occurs between switching between recording on the front side and recording on the back side. Further, since the sheets on which images have been formed are stacked and pressure is applied to them by the paper feed roller, there is also the problem that the back surface of this pressure section is stained by the image on the surface of the sheet below.

Purpose This invention provides a sheet that has been recorded on its front surface and is transferred from the paper ejection section to between the paper feed section and the image formation section into a series of paper feed section, image formation section, and paper ejection section, and an image formed by the image formation section on the back surface of the sheet. A sheet turning/returning means is provided to turn over and return the sheet to undergo formation, image formation is performed on n (n≧2) sheets in succession on the front side of the sheet, and the sheet after the surface recording is turned over and returned to the back side through the sheet turning/returning means. The images are formed on the front side of the n-th sheet, and then the images are formed on the back sides of the n sheets after the front side is recorded. It is an object of the present invention to provide a double-sided recording method that can eliminate the above-mentioned drawbacks of the conventional method by repeatedly performing recording operations as one block and performing double-sided recording on a large number of sheets.

Embodiment FIG. 1 shows an example of an electronic copying machine according to the present invention. In the figure, reference numeral 1 denotes a copying machine main body, and a photosensitive drum 2 is provided approximately at the center thereof so as to be driven to rotate in the direction of the arrow. Around the drum 2, a charging charger 3, an exposure slit part 4, a developing device 5, a transfer charger 6, a separation charger 7, a separating claw 8, a cleaning device 9, and an eraser lamp 10 are installed.
They are arranged sequentially in the 0-rotation direction, act on the same part of the surface of the drum in sequence as it rotates 20 times, and form an image forming section A that transfers a toner image onto copy paper that is synchronously conveyed. .

In the image forming section A, the portion of the surface of the photosensitive drum 2 that has been cleaned by the cleaning device 9 is first neutralized by the eraser lamp 10 and then charged by the charging charger 3 . A laser optical system 12 (described later) is connected to this charged surface of the drum 2 through the exposure slit section 4.
An electrostatic latent image (image pattern) is formed by sequentially irradiating image information from Next, this electrostatic latent image is developed with toner by a developing device 5, and the developed toner image is transferred by a transfer charger 6 onto a synchronously fed copy paper. Furthermore, the copy paper after the transfer is separated from the surface of the drum 2 by the separation charger 7 and the separation claw 8. After the copy paper has been separated and the surface of the drum 2 has been transferred, residual toner is scraped off by the cleaning device 9, and then the process returns to the static elimination process using the eraser lamp IO described above.

The laser optical system 12 diffracts the laser beam from the laser 13 using a modulator 14 to control on/off, the beam diameter is controlled by a lens system 15, and the lens system 15 is controlled by a polygon mirror 16 rotating at high speed. The reflected laser beam is irradiated onto the surface of the drum 2 through the exposure slit section 4 and scanned, thereby forming an image pattern as the electrostatic latent image on the surface of the drum 2.

On the left side of the image forming section A, there is a paper feed section B that feeds the copy paper between the transfer section, that is, the photosensitive drum 2 and the transfer charger 6, and on the right side of the image forming section A, there is a paper feed section B that feeds the copy paper between the photosensitive drum 2 and the transfer charger 6. A fixing device 17 that heats and fuses the transferred toner image on the copy paper separated from the drum 2 and a paper discharge section O that discharges the copy paper that has passed through the fixing device 17 are arranged in substantially horizontal rows near the bottom of the drum 2. It is arranged like this. In the paper feed section B, paper feed force plates (18a and 18b) for storing two types of copy paper Pa and pb of different sizes are mounted on top and bottom of the copying machine main body l in a state that they protrude to one side. By selectively driving the rollers 19a and 19b, one of the copy sheets pa and pb is fed to the paper feed path 20, passed through the intermediate roller pair 21 and the timing roller pair 22, and then to the transfer section below the photoreceptor drum 2. , the toner image is fed in synchronization with the movement of the toner image on the drum 2. Reference numeral 11 denotes a manual insertion section for copy paper.

Note that the cassettes 18a and 18b may be of the same size, or the size signal may be obtained from the cassettes.

The paper feed rollers 19a and 19b are driven by transmitting driving force from a power source (not shown) via a clutch mechanism including a known spring clutch and a solenoid, and the paper feed timing signal is based on the actuation timing of this solenoid. given as. In addition, the intermediate roller pair 21 is initially stopped, temporarily stops the copy paper pa or pb sent to the paper feed path 20 from one of the paper feed force rollers 18a and 18b, and is driven at an appropriate timing. is sent to the timing roller pair 22. The timing roller pair 22 is also initially stopped, and the copy paper Pa or pb sent from the intermediate roller pair 21 is temporarily stopped and outputted in synchronization with the toner image formed on the photoreceptor drum 2. The timing roller is driven by a timing roller activation signal and sent to the transfer section.

23 is a conveyor belt that sends the copy paper sent out from the transfer unit to the fixing device 17, and 24 is a discharge roller that discharges the copy paper sent out from the fixing device 17 to the paper discharge unit 0. The paper ejection section C is provided with a paper ejection tray 25 that receives and stacks the ejected copy sheets and stores them in a stacked manner. To the middle of 20, fuser 17
A sheet turning/returning means is provided for turning over and returning the copy paper after the front side recording has been subjected to image formation (toner image transfer) by the image forming section A on the back side.

The sheet turning and returning means is formed as a unit that is detachably attached to the lower flat space E provided below the paper feed section B1, image forming section A, and fixing device 17 of the copying machine main body 1. ing. The sheet is ejected from the sheet ejection section C, which has the sheet ejection tray 25 removably attached to one end of the copying machine main body 1 of the sheet turning and returning means, which protrudes toward the copy paper ejection side, and from the ejection roller pair 24. A switchback method is used to flip the copy paper after recording on the front side, and the copy paper discharged from the discharge roller pair 4 is selectively sent to either the paper discharge tray 25 side or the switchback passage 26 side. A guide pawl 27 is provided which can be switched to guide. The switchback passage 26 is a horizontal passage that is open at the top and slightly curved in a downwardly convex state that is shorter than the minimum number of copies used, and is provided with an introduction roller that introduces the copy paper sent downward from the guide claw 27 section. pair 28, 29 and the copy paper fully inserted into the short passage 26 and stretched;
It has a pair of delivery rollers 29 and 30 which share the one roller 29 and send out from the rear end.

Further, a portion of the sheet turning and returning means inserted into the flat space E at the lower part of the copying machine main body is provided with a portion of the sheet turning and returning means that receives the turned copy sheet sent out from the pair of sending rollers 29 and 30 of the switchback path 26, and A conveyor belt 31 that returns to the middle of the conveyor belt and a plurality of auxiliary rollers 3 in contact with the conveyor surface.
2, and the transport roller pair 33 are the feed roller pair 29.3.
They are sequentially arranged from 0 to the paper feed path 20 side. Paper feed path 20
A feeding port 34 for the copy paper to be turned over and returned is provided at a position before the intermediate roller pair 21 on the way, and the copy paper fed from the transport roller pair 33 to the feeding port 34 is fed into the feeding port 34. A curved copy paper return guide 35 is provided toward the intermediate roller pair 21 side of the paper feed path 20 to smoothly enter the copy paper in the upside down state. This guide 35 is fixedly installed within the main body l of the copying machine. The reversed copy paper fed into the paper feed path 20 from its feed port 34 is conveyed by a pair of conveying rollers 33 until it is sandwiched between a pair of intermediate rollers 21 . After receiving the same timing adjustment as described above (synchronization with the toner image on the photosensitive drum 2) by the timing roller pair 22, the toner image is sent to the transfer section, and the toner image is transferred or recorded on the back side in the same way as the front side.

The paper discharge tray 25 is designed to be able to be directly attached to the copying machine body J as shown in FIG. 3 after being removed from the sheet turning and returning means and the same means being removed from the copying machine body 1. Reference numeral 36 indicates a pair of auxiliary ejection rollers disposed in front of the mounting portion of the paper ejection tray 25 of the sheet turning and returning means, and reference numeral 37 indicates a pair of auxiliary ejection rollers 3 from the ejection roller pair 24 together with the guide claw 27.
6 side and the switchback path 26 side, respectively, are auxiliary feed rollers arranged at each copy paper path branching portion to the switchback path 26 side.

The copying machine main body 1 is further provided with a process control logic (paL) at its upper corner for sequentially controlling mainly mechanical operations of the copying machine. Further, the copying machine main body 1 is placed on a base 38. The base 38 is provided with a control unit (OU) that provides control signals to the process control logic (poL) and data signals to the laser optical system 12. This control unit (OU) receives various signals from an external computer, word processor, or storage device such as a magnetic disk (not shown). As a result, modulation control for the modulator 14 of the laser optical system 12 and control signals (synchronization signals with the laser optical system 12, etc.) for the process control logic (POL) are performed within the control unit (OU). processed and output. The base 38 is provided with a diskette 39 for mounting the storage device and sending signals to a control unit (oty), as well as 1. A connection section with external equipment such as the external computer or word processor is also provided.

The operation when copying on both sides of a sheet of copy paper will be described below.

Copy paper Pa in paper feed force (cera) 18a, 18b.

Either Pb is sent to the paper feed path 20 by the operation of the paper feed roller 19a or 191). After the copy paper is synchronized by adjusting the timing of the pair of intermediate rollers 21 and the pair of timing rollers 22, it is fed into a transfer section between the photosensitive drum 2 and the transfer charger 6, and the toner image on the drum 2 is transferred to the surface. Ru. The copy paper after transfer is transferred to the drum 2 due to the stiffness of the paper itself and the separate charger 7.
and is sent to the fixing device 17 by the conveyor belt 23. At this point, the toner image on the surface of the copy paper is fixed, and recording on the surface is completed.

The copy paper after front side recording is discharged to the paper discharge section 0 by the pair of discharge rollers 24, but the switchback is caused by the guide claw 27 being at the position shown by the broken line in FIG. Guided to aisle 26,
After being turned over, the conveyor belt 31 and auxiliary roller 32
Then, the paper is returned to the middle of the paper feed path 20 through the feed port 34 by the pair of transport rollers 33 . This paper feed path 20
After being synchronized by adjusting the timing of the intermediate roller pair 21 and the timing roller pair 22, the copy paper returned to the printer is sent back to the transfer section between the photosensitive drum 2 and the transfer charger 6, and the copy paper is transferred to the back side. The toner image on drum 2 is transferred.

The copy paper with the toner image transferred to the back side is separated from the drum 2 and sent to the fixing device 17 by the conveyor belt 23, where the toner image on the back side is fixed, in the same way as after the toner image was transferred to the front side. As a result, the copy paper completes recording on both sides and is ejected to the paper ejection section C via the ejection roller pair 24, but the guide claw 27 moves to the solid line position in FIG. By returning to its original state, it is guided toward the auxiliary discharge roller pair 36, and the roller pair 36
The paper is then discharged to the paper discharge tray 25.

Next, when double-sided recording is performed on a large number of sheets in succession, the processing speed becomes considerably slow if double-sided recording is performed on a single sheet, so in this invention, in particular, copying of n (n≧2) sheets is While continuously feeding paper and recording on the surface,
After recording on the front side, the copy sheets are sequentially turned over and sent back, and after recording on the front side of the nth sheet, recording is performed on the back side of one sheet of copy paper, and this double-sided recording operation is repeatedly executed as a -block. Both sides of a sheet of copy paper are recorded.

For example, to explain the case where n is 3 (the number of copies of copy paper to be recorded on both sides in a - block (hereinafter referred to as the block number of sheets less than or equal to C)), first, from the paper feed section B to the image forming section A, the first
Copy sheets P□ IPIIIP in the figure are sequentially and continuously fed, and recording can be continuously performed on their surfaces. Each copy paper P1 jP@ recorded on this surface
+ Ps is at the position shown by the broken line in Figure 1 until the copy paper P passes the front side recording due to the double-sided recording instruction with the number of blocks 3, so all the guide claws 27 are in the switchback path 2.
6, the paper is turned over and returned to the paper feed path 20, and the image forming section A sequentially records the back side. After the first copy paper P
When the copy paper is ejected to PI + P, the guide claw 27 is returned to the solid line position in FIG.
i*Pg is discharged to the paper discharge tray 25.

The image forming pattern exposed onto the photoreceptor drum 2 from the laser optical system 12 is determined in advance based on information such as the front, back, number of blocks n, etc., and is output in that order.

For example, when recording a continuous page with a block number of 3 and a portion of it, the first front side recording.

For the reverse side, pages 1 and 3.5 are sequentially output, and for the back side, pages 2, 4, and 6 are output sequentially, and the second time is Table 7.9.
．． After 11 pages, the back 8, 10, and 12 pages are output in sequence. Also, when recording for 3 copies using 3 blocks,
For the first front side record, all 1 page is output, and for the back side record, all 2 pages are output, and for the second time, all 3 pages are output for the front side record, and 4 pages are output for the back side record. .

If the block number n is as small as 3 compared to the length of the 4-copy paper double-sided recording circulation path Q shown by the broken line in FIG. After the toner image is transferred to the surface of the first copy paper P, the first copy paper P1 after surface recording is immediately sent to the transfer section between the photosensitive drum 2 and the transfer charger 6, thereby eliminating loss time. . This fast return method is more effective when the number of blocks is smaller, and is even more effective when double-sided recording is performed on a single sheet of copy paper.

Figure 4 shows the copy paper PI when the number of block sheets is n=3.
+ pH + p, the general standard of double-sided recording processing speed is shown. In other words, normal recording processing speed 13
For 0ss/a, the pair of intermediate rollers 21 between the feed roller pair 29 and 30 of the switchback path 26 and the paper feed path 20
The copy paper return speed is set to 600/8, which is about 4.6 times faster.

The copy paper size is 210 m5 (A4 horizontal feed), and the distance between the paper feed rollers 19a, 19b and the intermediate roller 21 is 100 m.
m, the distance from the intermediate roller 21 to the pair of switchback passage introduction rollers 28.29 is 650 songs, and the return distance from the pair of switchback passage delivery rollers 29.30 to the intermediate roller 21 is 1400 songs.

As a result, while the surface recording of P,', P,', P,' is performed sequentially with the normal interval time T, the surface recording of the third sheet P,' is performed after the same interval time T, Since the back side recording P,' of the first sheet is performed, and the back side recording pj', p,'' of the second and third sheets continues, there is no loss time due to double-sided recording.

If the desired number of sheets to be double-sided recorded is an integral multiple of the number of blocks, it is sufficient to repeat the block type double-sided recording by that multiple. On the other hand, if the number is less than the integral multiple of the number of blocks, then Block type double-sided recording is performed, and for sheets whose number is less than the block number, double-sided recording is performed for one sheet. For example, the number of blocks n=3
, and the desired number of sheets is 4, the fourth
As shown at P41 in the figure, after one-time block method double-sided recording is completed, recording is performed on the front side of the fourth copy paper at normal recording processing time intervals, and then one-time recording including fast reverse processing is performed. P4 after a predetermined recording processing time on the back side of
As shown by ', recording on the back side of the fourth copy sheet is completed.

In this case, as is clear from FIG. 4, there is a loss time between recording on the front side of the fourth copy sheet and recording on the back side. Of course, it is also possible to perform double-sided recording using a block method for double-sided recording of fewer sheets than the number of blocks, but a corresponding loss time will occur depending on the number of sheets that is a fraction of the number of sheets in the block. .

In order to solve this problem, double-sided recording for the desired number of sheets can be completed without excess or deficiency by using block type double-sided recording processing.

First, the number of blocks can be set arbitrarily. Next, for each set number of blocks, in order to immediately start recording on the back side of the first sheet after finishing recording on the front side of the set number of blocks,
The copy paper return speed is made variable according to the copy paper size and the number of blocks.

Figure 5 shows a general example of the return speed corresponding to each set number of blocks when the copy paper return speed is variable. Same conditions. The return speed is 600ss/a for blocks up to 3 sheets, which is the same as in Figure 4, but when the block number is 4 sheets, it is 300ss/8.5.
200wm/a for 6 sheets, 150s for 6 sheets
ll/B 17 sheets is 130ss/a, 8 sheets is 9518.9 sheets is 80ss/a, PR in Figure 5.
,,PR,.

..., IPR, the return speed is changed as the number of blocks n increases, and after recording p4', p,',...sP@' on the surface of the set number of blocks, 1 Recording on the back side of the first sheet is made immediately.

Assuming that the number of sheets in the block is 4, the recording on the surfaces of the 4 sheets of photocopying paper is PI' + Pg' +
After proceeding with Ps' sP, f, immediately record P, # on the back side.

P: + P, , p;' are performed in sequence, and double-sided recording of the four sheets is completed. The required time in this case is approximately 29 seconds,
As in the case of FIG. 4, n=3 is fixed and the last one is recorded independently on both sides of four sheets.

This significantly reduces the time required for double-sided recording, which is approximately 35 seconds.

In addition, in a normal recording device, it is undesirable to increase the number of sheets in the machine from the viewpoint of post-processing in the event of trouble. Therefore, if the number of sheets recorded in one recording is, for example, 9, Rather than setting the number of blocks n = 9, it is better to set n = 3 and repeat it 3 times.Also, even when the return speed is made variable and the number of blocks is made variable, the number of variable steps at that speed can also be changed. Less is better. Therefore, for example, in a machine where the number of basic blocks is n = 2, the fraction during recording is O or 1, so it is only necessary to provide a speed change mechanism that sets the final number of blocks to n = 3.
Similarly, in a machine with the number of basic blocks n = 3, the fraction is 0,
1.2, it is sufficient to provide a transmission mechanism that allows n=4 and n=5. That is, in a machine where the number of basic blocks is n=H, if the number of stages (N stages) from N to 2N-1 can be varied, the number of gears can be reduced and efficiency is improved.

Effects According to the present invention, a sheet turning and returning means is provided for turning over and returning the sheet after surface recording from the sheet discharge section to the middle of the sheet feeding path, and - first, image formation on the front surface of the sheet is continuously performed in units of the number of blocks. While performing the front side recording, each sheet after the front side recording is turned over and returned through the sheet turning and returning means so that the back side becomes the image forming surface, and then one block after the front side recording is performed after the front side recording in units of the number of blocks. By recording on the back side of a number of sheets and repeating this double-sided recording operation in blocks of sheets, double-sided recording is performed on a large number of sheets. +÷t -□- There is no need for an intermediate tray that is once stacked and stored. Therefore, the device does not become larger, and by not stacking the sheets after recording on the front side, there is an increase in the size of the sheets.As the sheets are stacked and are pressed by the paper feed roller, the image on the lower sheet stains the back side of the upper sheet. There will be no more. Furthermore, front side recording and back side recording for each block number of sheets are performed continuously by circular transport in which the sheets after front side recording are turned over and returned in order, thereby eliminating the loss time required to switch between front side recording and back side recording. Sequence control for double-sided recording is also easy.

[Brief explanation of the drawing]

FIG. 1 shows a cross section 7 showing an example of an electronic copying machine according to the present invention.
2 is a sectional view of the sheet turning and returning means removed from the copying machine main body, FIG. 3 is a sectional view of a part of the copying machine main body with the sheet turning and returning means removed, and FIG. FIG. 5 is a sheet processing speed diagram in block type double-sided recording. A...Image forming section, B...Paper feeding section, 0...Paper discharging section, D
... Sheet turning over and return means, 1... Copying machine body, 2
... Photosensitive drums 18a, 18b... Paper feed cassette, 25... Paper output tray, P jL * P t'
* P 1 1 P * s P * ”'Copy paper

Claims (1)

[Claims] (1) A paper feed section, an image forming section that forms an image on the surface of the sheet fed from the paper feed section, a paper ejection section from which the recorded sheet is ejected after passing through the image formation section, and a paper ejection section that A sheet turning/returning means is provided between the paper feeding section and the image forming section for turning over and returning the sheet after the front surface recording to have an image formed on the back surface by the image forming section, n(
n≧2) sheets in succession, and the n sheets after the surface recording are sequentially turned over and returned through the sheet turning and returning means so that the back side becomes the image forming surface, and image formation is performed on the front side of the nth sheet. Next, image formation is performed on the back sides of the n sheets after the front side recording, and double-sided recording is performed on a large number of sheets by repeatedly executing the double-sided recording operation on these n sheets as a block. Double-sided recording method featuring