JPS5821269A - 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 and returns the sheets recorded on the front side from a discharging part to the midway of a feeding line and executing recording on the rear side of the number of sheets in one block. CONSTITUTION:The copying paper which is recorded on the front side is returned to the mid-way of a feeding line 20 through its feed port 34. The paper returned to the line 20 is again fed in the state of the rear side up into a transferring part, where the toner images on a drum 2 are transferred thereon. Here, images are formed consecutively on the front side of n (n>=2) sheets and the n sheets recorded on the front side are successively turned over and the images are formed on the rear side of the n sheets recorded on the front side after the image formation on the front side of the n sheets. Such recording operations on both sides of the n sheets as one block are executed repeatedly. According to the information on the selected n number of the sheets and on the sizes of the sheets, the returning speed of said sheets is made variable.

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, in copying machines, etc., which were able to form images on both sides of a single sheet and record them, for example,
As is known from Japanese Patent No. 843, an intermediate retray is arranged between a paper feed cassette and a paper output tray, and each sheet fed from the paper feed section to the image forming section and imaged on the surface thereof is stored. ,
Once the sheets are stacked and stored in the intermediate tray, and the recording on the front side is completed, the sheets after the front surface recording, which are stacked and stored in the intermediate tray, are sent out and sent again to the image forming section, and images are created on each other side of the sheets. By recording, it is possible to record on both sides.

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 in the transfer process during surface recording acts between the sheets stacked in the intermediate tray after surface recording, and the sheets after surface recording are transferred from the intermediate tray to the sheets after surface recording. When feeding out one sheet at a time by a paper feed roller, there is a risk that a large number of sheets may be fed out at once. For this reason, intermediate i
A means is required to sufficiently eliminate static electricity from the sheets stacked and stored in the lay. Furthermore, the sheets μ after four recordings on the front side 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 for double-sided recording becomes complicated, and loss time occurs during switching between recording on the front side and recording on the back side. In addition, since the image-formed sheets are stacked and pressure is applied to them with a 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 turning device is provided to turn over and return the sheet to undergo formation, and continuously perform image formation on n (n≧2) sheets on the front surface, and turn over and return the sheet after the surface recording. The sheets are sequentially turned over and returned through a stage so that the back side becomes the image forming surface, and image formation is performed on the front side of the n-th sheet, and then image formation is performed on the back side of the nth sheet after the front side recording. By performing double-sided recording on a large number of n sheets, the above-mentioned drawbacks of the conventional method can be overcome. By making the sheet return speed variable, the number of sheets recorded on both sides in one block (hereinafter referred to as the number of sheets in the block) can be arbitrarily set, and it is also effective in processing fractional sheets of the number of sheets in the block when recording a large number of sheets on both sides. The purpose is to provide a double-sided recording method.

Embodiment FIG. 1 shows an example of an electronic copying machine according to Poko's invention. In the figure, reference numeral 1 denotes a copying machine main body, and a photosensitive drum 2 is provided approximately in the center thereof so as to be driven to rotate in the direction of the arrow. Around the drum 2, there are a charger 3 for charging, a slit section 4 for exposure, a developing device 5, a charger for transfer, a jar 6, a charger 7 for separating static electricity, and a separation claw 8.
, a cleaning device 9 and an eraser lamp 10 are sequentially disposed in the rotational direction of the drum 2, and as the drum rotates 20 times, they sequentially erase the same part of the surface of the drum and erase the copy paper that is being conveyed synchronously. Transferring the toner image, image area A
is doing.

In this image forming section A, the portion of the surface of the photosensitive drum 2 that has been cleaned by the cleaning device 9iK is first neutralized by an eraser and a bulb 10, and then charged by a charging charger 3. This charged surface of the drum 2 is sequentially irradiated with image information from a laser optical system 12, which will be described later, through the exposure slit section 4 to form an electrostatic latent image (image pattern). Next, this electrostatic latent image is developed with toner by a developing device 5, and the developed toner image is transferred onto a synchronously fed copy paper by a transfer charger and a roller 6. The copy paper is separated from the top five surfaces of the drum 2 by a separation charger 7 and a 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 a cleaning device 9, and then the above-mentioned eraser lamp 10
Return to the static electricity removal process.

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 laser beam is transmitted through the lens system 15 by a polygon mirror 16 rotating at high speed. Then, the beam is reflected and irradiated onto the surface of the drum 2 through the exposure slit section 4 and scanned, thereby forming an image pattern as the charged latent image on the surface of the drum 2.

On the left side of the image forming section A is a paper feed section B that feeds the copy paper into the transfer section, that is, between the photosensitive drum 2 and the transfer charger 6, and on the right side of the image forming section A is the A fixing device 17 that heats and fuses the transferred toner image on the copy paper separated from the drum 2 after transfer, and a paper discharge section C that discharges the copy paper that has passed through the fixing device 17 are located approximately near the bottom of the drum 2, respectively. They are arranged horizontally in rows.The paper feed section B has paper feed force cells 18a and 18b that store two types of copy paper Pa and pb of different sizes. The paper feed rollers 19a+19b are mounted on the top and bottom in a state that extends to the side.
By selectively driving the copy paper P a +
Pb is sent out to the paper feed path 20, and the intermediate roller pair 2
1 and a pair of timing rollers 22 to a transfer section below the photosensitive drum 2 in synchronization with the movement of the toner image on the drum 2. Reference numeral 011 is a manual insertion section for copy paper. Note that the cassettes 18a and 18bll'j may be of the same size, and the size signal may be obtained from the cassette.

- The paper feed rollers 19a and 19b are driven by transmitting the driving force from a power source (not shown) through a clutch mechanism such as a well-known spin-sink latch and a hydraulic current, and the paper feed timing is determined by A signal is given as the activation timing of this solenoid. In addition, the intermediate roller pair 21 is initially stopped, and the paper feeding force is 18.
Either one of a and tab temporarily stops pb and is driven at an appropriate timing, so that the timing roller pair 22
send to The timing roller pair 22 is also initially stopped, and temporarily stops the copy paper P, a or Pl:1 sent from the intermediate roller pair 21, and synchronizes it with the toner image formed on the photoreceptor drum 2. The timing roller is driven by the timing roller operation signal output from the timing roller and sent to the transfer section.

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

The sheet turning and returning means D is formed as a unit that is detachably attached to the lower flat space E of the copying machine main body 1, which is provided below the paper feed section B1, the image forming section A, and the fixing device 17. It has been. At one end of the sheet turning and returning means protruding from the copying machine main body 1 toward the copy paper ejection side,
A paper discharging section C to which the paper discharging Louis i5 is removably attached, a switchback path 26 for turning over the copy paper after surface recording discharged from the discharging roller pair 24 in a so-called switchback method, and a discharging roller pair 24. A guide claw 27 is provided that can be switched to selectively guide the ejected copy paper to either the paper ejection tray 25 side or the switchback path 26 side. The switchback passage 2'6 is open at the top and shorter than the minimum copy paper used, forming a slightly curved horizontal passage with a downward convex state, and is fed downward from the 27° portion of the guide claw. A pair of introduction rollers 28 and 29 introduce the incoming copy paper into the short path 26, and a pair of delivery rollers 29 share the one roller 29 to send out the copy paper from the rear end.・It has 30.

In addition, a switchback passage 2 is provided in the portion of the sheet turning and returning means that is inserted into the flat space E at the bottom of the copying machine main body.
A conveyor belt 31 that returns and feeds the flipped copy paper sent out from the pair of feed rollers 29, , and 30 of No. 6 to the middle of the paper feed path 20, a plurality of auxiliary rollers 32 in contact with the conveyance surface thereof, and a pair of conveyor rollers. 33 is a pair of delivery rollers 29
．． They are sequentially arranged from 30 to the paper feed path 20 side. A feeding port 34 for the copy paper to be turned over and returned is provided at a position before the pair of intermediate rollers 21 in the middle of the paper feeding path 20.

The feed port 34 has a curved copy paper return guide that allows the copy paper sent from the transport roller pair 33 to the feed port 34 to smoothly enter the intermediate roller pair 21 side of the paper feed path 20 with the copy paper turned over. 35 are provided. This guide 35 is fixedly installed within the copying machine main body 1. The copy paper sent into the paper feed path 20 from the feed port 34 and returned through the back gate is to be transported by the transport roller pair 33 until it is sandwiched between the intermediate roller pair 21,
After receiving the same timing adjustment as described above (synchronization with the toner image on the fi light drum 2) by the intermediate roller pair 21 and 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. I try to accept it.

The paper discharge tray 25 can also be directly attached to the copying machine main body 1 as shown in FIG. 3 after removing it from the sheet turning and returning means and removing the same from the copying machine main body 1. Reference numeral 36 indicates a pair of auxiliary ejection rollers disposed in front of the paper ejection tray 5 attachment section of the sheet turning and returning means, and reference numeral 37 indicates a pair of auxiliary ejection rollers from the ejection roller pair 24 to the auxiliary ejection roller pair 3 together with the guide claw 27.
This is an auxiliary feed roller arranged at each copy paper path branching portion to the 6 side and the switchback path 26 side.

Inside the copying machine main body 1, there is further located at the top corner a process for controlling the sequence of the main mechanical operations of the copying machine.
Control logic (POL) is provided.

Further, the copying machine main body 1 is placed on a base 38.

This base 38 is provided with a control unit (OU) that provides a control signal to the process control logic (POL) and a data signal to the laser optical system 12. It is being

゛This control unit) (OU) Ha, Il
Displays and receives various signals from an external computer, word processor, or storage device such as a magnetic disk. As a result, the modulator 14 of the laser optical system 12
Control signals (synchronization signals with the laser optical system 12, etc.) for the modulation control and process control optical system (POL) are controlled by the control unit) (O
Processed in U) and output. The base 38 is provided with a diskette 39 to which the storage device is attached and which sends signals to the control unit (OU), as well as a connection section with external equipment such as the external computer or word processor (not shown). The following describes the operation when copying on both sides of a sheet of copy paper. .

Copy paper Pa in 18 a r 18 b
.

pb is the paper feed roller 19ai or i'9.
The paper is fed to the paper feed path 20 by the operation b. After the copy paper is synchronized by timing adjustment of the pair of intermediate rollers 21 and the pair of timing rollers 22, it is fed into the transfer section between the photosensitive drum 2 and the transfer charger 6, and the surface of the copy paper is coated on the drum 2. The toner image is transferred. The copy paper after transfer is
The paper is separated from the drum 2 by its own stiffness and the separation charger 7, and is sent to the stabilizer 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 surface recording is discharged to the paper discharge section O by the discharge roller pair 24, but because the guide claw 27 is at the position of the broken line, the copy paper is guided to the switchback passage 26, and is guided to the switchback passage 26. After the paper is turned over at 26, the paper is transferred to the feed path 2 by the conveyor belt 31, the auxiliary roller 32, and the conveyor roller pair 33.
0, it is returned through the navel inlet 34.

The copy paper returned to the paper feed path 20 is placed face down by an intermediate roller pair 21 and a timing roller pair 22.0.
After synchronization by timing adjustment, the toner image on the drum 2 is transferred to the back side of the photosensitive drum 2 and the transfer portion between the photosensitive drum 2 and the transfer charger 6.

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. be done. As a result, the copy paper completes recording on both sides and is ejected to the paper ejection section 0 via the ejection roller pair 24, but the guide claw 27 is instructed to record both sides of the copy paper as shown in the solid line in Figure 1. By returning to the position, it is guided to the auxiliary discharge roller pair 36 side, 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 one sheet, so in this invention, in particular, n (n≧2) While continuously feeding sheets of copy paper and recording on the front side, the copy paper after recording on the front side is sequentially turned over and sent back.
After recording on the front side of the n-th copy paper, recording is performed on the back side of the nth copy paper, and by repeatedly executing this double-sided recording instruction as one push, double-sided recording is performed on a large number of copy papers. ing.

For example, to explain the case where the number of right copy sheets for double-sided printing in one block (hereinafter referred to as the number of sheets in the block) is 3, first, from the paper feed section B to the image forming section A, the first
Copy sheets P1, P2, and P3 in the figure are sequentially and continuously fed, and recording is continuously performed on their surfaces. Each copy paper recorded on this surface pl r P2
+ P3 is in the switchback path 2 because the guide claw 27 is at the position shown by the broken line in FIG.
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. The first copy paper P.

When the paper is discharged to the paper discharge section C by the discharge port-ra pair 24 after being recorded on both sides, the guide claw 27 is returned to the solid line position in FIG. Copy paper PHr
P2 + P3 are 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, if the number of blocks is 3 and consecutive gifts are partially recorded, 1 + 3t5 pages will be output sequentially for the first front side recording, and 2 and 4.6 pages will be output sequentially for the back side recording. The second time, the front page 7, page 9111, and the back page 8, 10.
．． Output 12 pages in sequence. In addition, when recording for 3 copies with 3 blocks, all 1 sheet is printed for the first front side recording.
For the back side recording, all two pages are output, and for the second time, all three pages are output for the front side recording, and for the back side recording, four pages are output.

If the block number n is as small as 3 compared to the length of the 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 copy paper P3, the first copy paper P after the 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 less than 7, and is even more effective when recording on both sides of a single sheet of copy paper.

Figure 4 shows copy paper P1 when the number of block sheets is n=3.
A general example of the double-sided recording processing speed for 1F2 1P3 is shown. That is, the normal recording processing speed is 130
ss/s, from the feed roller pair 29.30 in the switchback path 26 to the intermediate roller pair 2 in the middle of the paper feed path 20.
The copy paper return speed up to 1 is 600 ss/s, which is about 4.
It is set to 6 times. The copy paper size is 21011B.
・(, A4 horizontal feed), paper feed slot, -ra 19 a w i
The distance between 9b and the intermediate roller 21 is xoOm, and the switchback passage is introduced from the intermediate roller 21.Roller pair 28s
29 to 65012B, the return distance from the switchback path 29.30 to the intermediate roller 21 is 14 (l [JWI).

Based on this, P1', + P2''',' p
a7 and the front side recording are performed sequentially with the normal interval time T, whereas the back side recording P of the first sheet is performed after the same interval time T from the front side recording P3' of the third sheet.
1'' is performed, and the back side of the second and third sheets is recorded p 2/l,
P3”, so there is no loss time for recording both sides.

The desired number of sheets for double-sided recording is the same as the number of blocks.

If it is several times as many times as that, then the block type double-sided recording can be repeated for that multiple number of times.However, if the number is less than an integer multiple + the number of blocks, then the integer multiple is 'block type double-sided recording. If the number of sheets to be recorded is smaller than the number of blocks, double-sided recording will be performed for one sheet.For example,
If the number of block sheets is set to n = 3 and the desired number of sheets is 4, the normal recording processing time interval after the completion of double-sided recording by one block method, as shown by P4/ in Fig. 4. Recording is performed on the front side of the fourth sheet of copy paper, and then, after a predetermined recording processing time for the back side of the fourth sheet including fast reverse processing, recording is performed on the back side' of the fourth sheet of copy paper as shown at P4''. ends.

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 block-based double-sided recording processing for double-sided recording of a number of sheets that is smaller than the number of blocks, but loss time will occur depending on the degree of 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 a desired number of sheets can be completed without any shortage by using a block type double-sided recording process. Therefore, in the present invention, the number of blocks can be set arbitrarily. Next, for each set number of blocks, the copy paper size and number of blocks must be adjusted so that the back side of the first sheet is recorded immediately after the front side of the set number of blocks has been recorded. Accordingly, the speed at which the copy paper is returned is made variable.
゛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.
The conditions are the same as in the case of FIG. The return speed is 600 ss/s when the number of blocks is up to 3, which is the same as in Figure 4, but when the number of blocks is 4, it is 300 ss/s.
ss/s, when there are 5 pieces, it is 200 Peng/B when there are 16 pieces, it is 1
50 lie / 8% 1.30Mb when 7 pieces
/B, 8 sheets @Id9'5wb/s.

When there are 9 sheets, it is 80 m/s, and PH1 + PH1 is shown in Figure 5.
As shown by r...1PR9, the return speed is changed as the number of blocks n increases, and recording is performed on the surface of the set number of blocks? 41, P,,...,P9
' After that, recording on the back side of the first sheet is immediately performed.

Assuming that the number of sheets in the block is 4, the recording on the surfaces of 4 sheets of copy paper is P L' + P'2' r
After proceeding to P 3' rp, /, the recording on the back side is immediately performed sequentially as P1, P2, HP3' t P4, and recording on both sides of the four sheets is completed.The time required in this case is approximately 29 seconds. As in the case of Fig. 4, when n = 3 is fixed and the last one is recorded on both sides independently, the time required to record both sides of four sheets is significantly reduced, compared to about 35 seconds. .

In addition, in a normal recording apparatus, it is not preferable to increase the number of sheets existing in the machine in consideration of post-processing in the event of trouble.

Therefore, if the number of recorded sheets is 9, for example, rather than setting the block number n = 9, it is better to set it to n-3 and repeat it 3 times.Also, by making the return speed variable, the number of blocks can be varied. It is also preferable that the number of speed variable steps in the Tokiba stand is also small. Therefore, for example, in a machine with the basic block number n = 2, the fraction at the time of recording is O or 1; therefore, it is sufficient to provide a speed change mechanism that changes the final block number to n = 3, and the basic i-lock number Similarly, for a machine with n = 3, the fraction is 0. l.

2, it is sufficient to provide a transmission mechanism that can set n = 74 and n = 5. That is, the number of basic blocks "n=N
In this machine, if the number of stages (N stages) can be varied from N to 2N-1, the speed change R'lk can be reduced and efficiency is improved.

Effects According to the present invention, there is provided a sheet turning and returning means 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 one block of sheets. After recording the surface, each sheet was turned over through the sheet turning means and turned over so that the back side became the image forming surface.

Then, after the front surface recording in units of 1 block number □, recording is performed on the back sides of the 1 block number of sheets after the front surface recording, and repeating this double-sided recording operation in units of 1 block number □. Accordingly, since double-sided recording is performed on a large number of sheets, there is no need for an intermediate tray for temporarily storing the sheets after front-surface recording, as in the prior art. Therefore, the device does not become large in size, and since the sheets 4 after surface recording are not stacked, there is no need to eliminate static electricity to prevent the sheets from being attracted, and the sheets after surface recording are stacked and subjected to pressure by the paper feed roller. , the back side of the upper sheet is locked to the image on the front side of the lower sheet, and the front and back side recordings for each number of sheets are performed continuously by circular transfer in which the sheets after front side recording are arbitrarily turned over and returned in order. There is no loss time to switch between front side recording and back side recording, and there is no sequence required for double-sided recording.
Control is also simple.

In particular, in this invention, the return speed of the sheet after the front surface recording is made variable according to the selected professional, information on the number of vines, and information on the sheet size, so there is no loss in switching between front surface recording and half surface recording. The number of blocks can be arbitrarily set for various sheet sizes without causing problems, and the number of blocks can be selected so that no odd number of sheets occurs during double-sided recording of a large number of sheets, or the number of block sheets that minimizes the loss time even if a fractional number of sheets occurs. By doing so, double-sided recording of a large number of sheets can be achieved in a time-efficient manner.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of an electronic copying machine according to the present invention, FIG. 2 is a cross-sectional view of the sheet turning and returning means removed from the copying machine body, and FIG. 4 and 5 are sheet processing speed diagrams in block double-sided recording. A: image forming section, B: feeding section. Paper section, 0...Paper output section, D
... Sheet turning over and return means, 1... Copying machine body,
2... Photosensitive drum, 18 a + 18 b...
Paper cassette, 25...paper output tray, Pa+Pb*P
1 1F'2 +P3 ''', 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 sheet is ejected after being recorded after passing through the image formation section, and a paper feed section that is fed from the paper ejection section. A sheet turning/returning means is provided between the paper section and the image forming section to turn over and return the sheet after the surface recording is performed so that an image is formed on the back surface by the image forming section. n≧2)
The nth sheet after recording the surface? - sequentially turning over and returning the sheets through the sheet turning and returning means so that the back side becomes the image forming surface, forming an image on the front side of the nth sheet, and then forming an image on the back side of the nth sheet after recording the front side; By repeatedly performing the double-sided recording operation on these n sheets as a block four, it is possible to perform double-sided recording on a large number of sheets.
A double-sided recording method characterized in that the return speed of the sheet is variable according to information on the selected number n of sheets and information on the width of the sheet.