JPS58181063A - Both-side copying machine - Google Patents

Abstract

PURPOSE:To refeed a one-side copied sheet and to execute a reverse side copy without any failure from the first transfer paper sheet, by using an intermittently driven belt in place of the intermediate tray of a both-side copying machine. CONSTITUTION:A transfer paper sheet having a toner image on one side in transfer stations 6, 7 is sent to a switch-back station (d) with a changeover claw 27a. The rear end is changed into the front end there, and then, fed to the feedback (g) belt 31 intermittently driven at each sheet. The one-side copied sheets stacked with the front ends each shifted little by little in the feed direction are refed with a roll 33, inverted upside down on an inversion station (f), and a toner image is transfered onto the reverse side of each sheet at transfer stations 6, 7. The both-side copied sheet is ejected onto a ejection tray 25 by displacing the claw 27.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a double-sided copying machine capable of copying on both the front and back sides of copy paper.

BACKGROUND TECHNOLOGY Conventionally, in the past, as known from Japanese Patent Publication No. 53-97843, an intermediate tray was disposed between upper and lower paper feed cassettes and a paper output tray, so that copies could be made on both the front and back sides of copy paper. The light-polluted copy papers supplied from the paper feed section to the image forming section and copied onto the front surface are once stacked and stored in the intermediate tray, and after the copying on the front surface is completed, the front surface copies are stacked and stored in the intermediate tray. The second copy paper is fed out one after another, re-sent to the image forming section, and copied on the back side of each copy paper, making it possible to make copies on both the front and back sides. and paper output F
Since an intermediate tray for double-sided copying must be provided between the copying machine and the copying machine, the size of the copying machine increases. In addition, in the intermediate tray, the copy sheets after front side copying, which tend to have residual electrostatic adsorption force due to corona charge in the transfer process during front side copying, are stacked and stored in an orderly manner. When I try to send or take out a single sheet of copy paper for backside copying, the sheets are electrostatically attracted to each other without being misaligned, so it is difficult to send out a single sheet, and multiple sheets overlap. It is also difficult to sort out the entire exposed photographic paper sent out one by one, and there is a risk that a plurality of sheets of copy paper after front-side copying will be used for back-side copying at the same time.

Furthermore, when the paper feed roller feeds the copy sheets stacked in the intermediate tray after front side copying to one sheet, the copy paper comes into pressure contact with the paper feed roller and is rubbed strongly against other sheets. and because of copying images, etc., they become contaminated with each other.

Purpose This invention is to switch back and return a sheet of paper after the front side has been copied by the normal copying means to the image forming unit side of the copying means, and then send it back to the image forming unit in a reversed state and make a copy on the back side. A double-sided copying auxiliary means is provided, and the return section of the double-sided copying auxiliary means can be driven independently, and the duplexing means is intermittently driven to continuously copy a fixed amount each time, so that the double-sided copying means receives one after another. After copying the surface of each copy paper,
In the process of returning to the image forming unit, the returning unit is returned in an overlapping state that is misaligned by one drive amount, and the copy paper after the first surface copy reaches a predetermined return position. It is an object of the present invention to provide a double-sided copying machine which eliminates the above-mentioned drawbacks of the conventional copying machine by sequentially sending back each copy paper stocked in the process after front-side copying to an image forming section so that back-side copying can be continuously performed. That is.

Embodiment FIG. 1 is an internal mechanism diagram showing an example of a double-sided electrophotographic copying machine according to the present invention. In the figure, a photosensitive drum 2 is provided approximately at the center of the main body of the machine, such as a flywheel, so as to be driven to rotate in the direction of the arrow. Around the drum 2, there are a charging charger 3, an exposure slit section 4, a developing device [5, a transfer charger 6, and a separation charger 7].
, a separation claw 8, a cleaning device 9, and an eraser lamp lO are sequentially arranged in the direction of rotation of the drum 2 shown by the arrow, and act on the same part of the surface of the drum in sequence as the drum 20 rotates. In this image forming section a, a portion of the surface of the photoreceptor drum 2 that has been cleaned by the cleaning device 9 is First, the static electricity is removed by the eraser lamp 10, and then the static electricity is charged by the charging charger 3. The image of the document placed on the document placement glass 12 on the top surface of the main body l is exposed to light by the scanning optical system 13 through the exposure slit section 4 on this charged surface of the drum 2, forming an electrostatic latent image. do. 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 copying paper by a charger 6.
transcribed by. 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 being removed, the process returns to the static elimination process using the eraser lamp IO described above.

Reference numeral 14 denotes a document pressure bonding plate, which is attached to the main body 1 so as to be able to be opened and closed relative to the document placement glass 12. 15 is an imaging lens in the scanning optical system 13.

On the left side of the image forming section a is a paper feeding section 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 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 0 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 in such a way that it constitutes a normal copying means. The paper feed section (18m, 18b) accommodates two different sizes of copy paper P& and PB.
It is mounted on the top and bottom of the copying machine with its extension extending to one side of the main body.
When the paper feed rollers 19a and 19b are selectively driven, one of the copy sheets Pa+Pb is sent out to the paper feed path 20, passes through a pair of temporary stop adjustment rollers 21 and a pair of auxiliary timing rollers 22, and then passes under the photosensitive drum 2. The toner image is sent to the transfer section in synchronization with the movement of the toner image on the drum z.

Reference numeral 11 denotes a manual insertion section for copy paper.

The paper feed rollers 19m and 19b are driven by transmitting driving force from a power source (not shown) via a known clutch mechanism including a 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 pair of temporary stop adjustment rollers 21 is initially stopped, and once receives the copy paper P1 or pb fed from one of the paper feed cassettes (tea and 18m) to the paper feed path 20, and corrects the skew. The pair of 0 auxiliary timing rollers 22, which are driven at appropriate timings together with the pair of 0 auxiliary timing rollers 22, which feed the pair of auxiliary timing rollers 22, are also initially stopped, and the pair of temporary stop adjustment rollers 2
The copy paper (P & or PI) sent from the photosensitive drum 2 is temporarily stopped and transferred by being driven by a timing roller activation signal output in final synchronization with the toner image formed on the photoreceptor drum 2. Send it to the department.

Reference numeral 23 denotes a conveyor belt that sends the copy paper sent out from the transfer section to the fixing unit 17, and 24 a discharge roller that discharges the copy paper sent out from the fixing section 17 to the paper discharge section O. The paper ejection section O is provided with a paper ejection tray 25 that receives and stacks and stores ejected copy sheets.

Below the copying means, there is a double-sided copying auxiliary means for returning the copy paper after the front side has been copied by the copying means to the image forming unit a side, and causing the image forming unit to send the copy paper with the front side reversed and make a copy on the back side. It is provided. The double-sided copying auxiliary means includes a switchback unit d that exchanges the leading edge and trailing edge of the copy paper after front side copying and returns it to the image forming unit 1 side, and a switchback unit d that switches back and returns the front end of the copy paper after front side copying to form an image. It becomes entangled with the front-back reversal section f, which is sent back to section a in a reversed state.

The switchback unit d is formed in a horizontally elongated shape and is detachably attached to a lower flat space e provided below the paper feed section 1, the image forming section a, and the fixing device 17 of the copying machine main body L. There is. switchback unit) (a paper discharge unit in which the paper discharge tray 25 is removably attached to one end protruding from the copying machine main body 1 toward the copy paper discharge side, and the discharged copy paper is sent to the tray 25) A paper discharge section O having a pair of rollers 34, a switchback section 26 that switches back the copy paper after surface copying discharged from the pair of discharge rollers 24, and a switchback section 26 that switches back the copy paper discharged from the pair of discharge rollers 24. A paper passing direction switching gate 27 is provided with a guide claw 27m that allows the paper to pass to the paper discharge tray 25 side or to be received by the switchback section 26 in accordance with a selection signal for single-sided copying or double-sided copying before the copying operation. The switchback section 26 has a switchback path 26m which is open at the top and has a short length of the minimum copy paper used and is curved downward in a convex state, and a switchback passage 26m that is open at the top and has a short length of the minimum copy paper used. It has a pair of introduction rollers 28, 29 for introducing the paper, and a pair of delivery rollers 29, 30 for sending out the copy paper from the rear end by sharing the one glue 29 and pulling the copy paper completely into the short switchback path 26&. ing.

Further, in the portion of the switchback unit d that is inserted into the flat space below the copying machine main body, the copy paper whose leading and trailing ends have been exchanged and which has been sent out from the pair of delivery rollers 29 and 30 of the switchback passage 26 & is placed in the image forming section. A return section (g) consisting of a return bell (31) that returns the paper to side a and a plurality of auxiliary rollers 32 in contact with the conveying surface thereof, and a return section (g) that sends the returned copy paper to the paper feed path 2o and sends the copy paper to the paper feed path 2o. A pair of back side copy paper feeding rollers 33 for feeding and returning the sheet from the sheet to the image forming section a are sequentially arranged from the pair of sending rollers 29 and 30 of the switchback path 26 & toward the sheet feeding section side in the sheet feeding path 20. Temporary stop adjustment q- from paper feed roller pair 33 to paper feed path 20'' II!
The paper feed path 20V is guided to a position in front of the paper feed roller pair 21, and the copy paper after the surface copying sent out from the paper feed roller pair 33 is guided.
c The reversing section f for reversing the front and back and sending it back is fixedly installed inside the copying machine main body l. The reversing section f is formed by a curved passage 16 that allows the returned copying paper after front-side copying to smoothly enter the pair of temporary stop adjustment rollers 21 into the paper feed path 2o with the front and back sides reversed. .

As shown in FIGS. 2 and 3, the double-sided copying means includes a gear 36 connected to the drive side of the pair of discharge rollers 24 of the main body 1.
In contrast to the intermediate gear 37 that meshes with the switchback unit and reverses the direction of rotation, the passive gear 37 provided in the switchback unit
8 are engaged with each other when unit)+1 is installed, and other parts of the return section g except for the return bell) 31 are driven simultaneously with the copying means, and the return belt 31 is driven independently by a stepping motor 43. There is. The rotation of the passive gear 38 is first caused by the timing belt 39 at the paper discharge port i.

The rotation of the roller 29 is transmitted to the other pair 34 and the roller 29 of the switch pack section 26, and the rotation of the roller 29 is transmitted to the back copy paper feed roller pair 3 by the gear 40° 41 and the timing belt 42.
3, and the system speed in the copying means (for example, 13611/a@o, the number of copies per unit time is 25 sheets/vals, the copying cycle is 2.4
g+.07 sheets) On the other hand, the return belt 31 is driven intermittently for a fixed amount each time the copying means continuously makes copies. For example, in a case where the transmission by the timing belt 44 from the motor 43 to the return belt 31 is represented by a pulley ratio of 1:1, and the diameter p of the used pulley is 318 cm, the motor 43 is driven by a two-phase excitation method. Then, when the stepping angle α of the motor 43 is 18°, the driving amount t of the return belt 31 per pulse is 0.5 m from α, and the driving amount t of the return belt 31 per pulse is 0.5 m. , 36 pulses are sent to the motor 43, and the return bell 31 is intermittently driven to 1811a.Thus, each copy sheet after the surface copy that is sequentially sent from the switchback section 26 onto the return belt 31 at the system speed is returned. 1g each time the surface copy is continuously made in the copying means, and is returned to the image forming section a side by the belt 31, and 18. In a state where the destination position is shifted, the following items are sequentially returned with overlaps with the preceding items (FIG. 4).

Now, let the length of the paper path on the return belt 31 be SSO■, and consider the case where copy paper is fed horizontally in A4 size. 3
By the time 3 copies have been reached and the preparation for backside copying is completed, which allows feeding of backside copies, there will be (5801IJ21 (lI&I) ÷ 18M - 20 of the sheets
From the distance M) up to the point of sheet restriction, a maximum of 20 sheets of copy paper after front side copying are stored.

When the back side copying is ready, the first copy sheet on the return bell) 31 is placed at a predetermined position 1i1iK in the return unit g after the start of frontside copying.
When the original is reached (Fig. 4), it is detected by the photo sensor 35's detection operation, and the front side of the original is replaced in order to replace the original for back side copying or to flip the front and back sides of the original before starting back side copying. 1kIvI When the copy preparation completion state is detected, both the manual copying and double-sided copying auxiliary means are temporarily stopped, and the start of backside copying is performed by operating a backside copying switch (not shown). The paper feeding station in the means is kept inoperative so that normal paper feeding from the cassettes 18&, 18b is not performed.

As a result, in the image forming section a, only the copy paper after front side copying, which is stocked on the return bell) 31, is turned over by the back side copy paper feed roller pair 33 via the reversing section f. Then, while the paper feed path 20 is being stopped, the adjustment roller pair 21. After the timing is adjusted by the pair of auxiliary timing rollers 22, the sheets are sent back at appropriate timing and are successively copied onto the back side. The time interval during which each copy sheet on the return belt 31 reaches the pair of paper feed rollers 33 and is subjected to reverse side copying is 18 m/7. 5w/sea m2
．． 4 Sea and Nasho, since back side copying is performed at a rate of one page every 24 seconds, it is equivalent to the normal copying cycle in the case of front side copying, and a large number of back side copies can be achieved with the same efficiency.O After back side copying The guide claw 27&, which had been switched to receive the copy paper after front side copying into the switchback unit (l) due to the double-sided copying operation, is returned to its original position by the operation signal of the back side copy start switch, etc. Depending on the situation, the maximum number of copies that can be made by making double-sided copies 0- times when the paper is passed from the paper ejection roller pair 24 to the paper ejection section O, and sent out onto the paper ejection tray 25 via the paper ejection roller pair 34 is the maximum number of copies that can be made by This is 20 copies, which is equal to the maximum number of copies that can be stocked on the belt 31, but in the case of general copying work, copying of more than 20 copies is rarely done, so there is no practical problem. Of course, it can be arbitrarily set depending on the length and the amount of one drive.

If the required number of copies for one double-sided copying is less than 20 copies, after the required number of front side copies are completed, the first copy sheet will be held for 20 minutes until it reaches the predetermined position on the return bell (31) where the back side is ready for copying. It will take the same amount of time as for copying the front side, but between the time the front side copy is completed and the back side copy preparation is completed, one original is replaced for the back side copy, or the front and back sides are reversed, and the back side copy is completed. Since you can start copying the back side as soon as preparation is complete, there is no wasted time.

The means for detecting that the copy paper after front side copying has reached the back side copying ready position on the return bell 31 is the tl of the 7-off sensor 35, a reed switch, a microswitch, or an ultrasonic sensor. In addition, various drive and transmission means using various other dedicated motors, solenoids, clutches, ratchets, etc. can be used for independent intermittent drive of the return bell (31).

In the case of the above embodiment, in order to make double-sided copies of 20 or more copies,
The double-sided copying operation must be repeated as many times as necessary for each set of 20 copies. If double-sided copying is performed with a set of 20 or more copies, trouble may occur depending on the method of transition from front-side copying to back-side copying, but when the duplex copying switch is operated, the number of copies set The easiest way to deal with this is to compare the number of copies with the maximum number of copies, and if the number of copies set is greater than the maximum number of copies, issue a warning with a lamp or buzzer and prevent the copying operation from starting.

The pair of rear copy paper feed rollers 33 collides the copy paper after front copy, which has been sent back from the middle of the paper feed path 20 to the image forming section a, against the pair of pause adjustment rollers 21 to correct the direction of the leading edge. In order to prevent skewing due to and K and to properly adjust the timing of feeding and returning to the image forming section a, the speed is slightly faster than the system speed, for example, 15 to 306 H/I.
It is desirable to drive with @O.

The copy sheets after the front side copying are returned in an overlapping state on the low-speed return bell) 31, and are shifted from each other by, for example, 1g, and each copy is made from the earliest one to the next. By ensuring that each sheet is bitten into the back side copying paper feed sealer pair 33, it is supposed to be used for backside copying of one sheet. However, in reality, it is difficult to pull out stacked copy sheets one by one from the first copy sheet below without pulling the top copy sheet, so appropriate gates, brake members, etc. Therefore, it is desirable to prevent the next copy sheet from accompanying the first copy sheet.

Alternatively, instead of the upper roller of the pair of rear copy paper feed rollers 33, a pad 51 made of polyurethane rubber or the like that is in pressure contact with the lower roller 33 may be provided as shown in FIGS. 6 and 7;
As shown in FIG. 9, the reversing p-rollers are arranged on both sides of the upper p-roller 33 and fixed to its support shaft 52, and have a slightly smaller diameter than the upper roller 33 and are driven in the opposite direction to the conveying direction. 53 may be provided to separate subsequent copy sheets and prevent double feeding, and if used in conjunction with the gate and brake member described above, prevention of double feeding becomes even more reliable.

Furthermore, as another double-feed prevention means, the distance t (FIG. 10) between the final auxiliary roller 32 and the back side copy paper feeding roller pair 33 in the return section g can be set to It is slightly shorter, for example, in the case of A4 size horizontal feed, 19
When setting 2vsx<1<210m, the first vI zero paper is bitten into the paper feed roller pair 33 by the start of return synchronized with the front surface copying by the copying means, and is therefore always sent to the next reversing section f. On the other hand, the subsequent copy paper is forcibly stopped just before it is bitten by the pair of rollers 33, being sandwiched between the return bell 31 (which is stopped until the next copying time) and the auxiliary roller 32. , double feed will never occur.

In addition, as shown in FIG. 11, the distance t is set between the back copy paper feed roller pair 33 and the temporary stop adjustment roller pair 21, and the paper feed roller pair 33 is driven intermittently in the same manner as the return bell) 31. Then, while the complete prevention of double feeding is achieved between the paper feed roller pair 33 and the temporary stop adjustment roller pair 21, the distance 192 + between both roller pairs 33 and 21 is then achieved.
u < 1 < 210w can also be used as the return range for stocking copy paper after surface copying, so the maximum stock amount,
In other words, the maximum number of copies possible with - times of double-sided copying is A4
In the case of cross-feeding, the number of copies can be increased to 30 or more.

Effects According to the present invention, the copy paper after front side copying is switched back to the image forming unit side of the copying unit, and is sent back to the image forming unit with the front side reversed and a copy is made on the back side. A double-sided copying auxiliary means is provided, and the return section of the double-sided copying auxiliary means can be driven independently, so that it is intermittently driven for a fixed amount each time continuous copying is performed in the copying means. In the process of returning each sheet of copy paper after front side copying is returned to the image forming unit in a stacked state whose position is shifted by one drive amount of the returning unit, the first copy paper after front side copying is returned to the specified position. On the condition that the paper reaches the return position, each of the copy sheets stocked in the return process after front side copying is sequentially sent back to the image forming section so that the back side copies can be made continuously.1. Efficient double-sided copying in which front-side copies and back-side copies are continuously made to a large number of sheets is possible without providing an intermediate tray, and the need for an enlarged apparatus is eliminated. In addition, when the copy sheets after front side copying are stocked during the process of returning them to the image forming section, there is always a certain amount of misalignment due to the intermittent drive of the returning section, and a large number of sheets of copy paper are stored in the intermediate tray. The degree of adhesion is slight compared to when sheets are stacked and stocked in an orderly manner, and when copy sheets are returned at low speed after surface copying, only the first one is always sent to the paper feed roller, which is sent back to the image forming section at system speed. Since it is bitten and used for back-side copying, it is easy to prevent double feeding during back-side copying, and it is also possible to prevent stains due to pressure contact between the paper feed roller and the copy paper stocked on the intermediate tray as in the past. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an internal mechanism diagram of a double-sided electrophotographic copying machine showing an embodiment of the present invention, FIGS. Figure 6 and Figure 7 are partial side views and sectional views of other embodiments, and Figures 8 and 9 are partial side views and cross-sectional views of another embodiment. A cross-sectional view, FIG. 10 is a partial side view showing another embodiment, and FIG. 10 is a partial side view showing still another embodiment. 43...Step motor Fig. 2 Fig. 4 Fig. 1 Fig. 5

Claims (1)

[Claims] (1) A paper feed section, an image forming section that forms a copy image of the original on one side of the copy paper supplied from the paper feed section, and a paper discharge section that discharges the copy paper after it has been copied through the image forming section. A double-sided copying means is attached to the copying means, which returns the copy paper after the front side has been copied by the copying means to the image forming unit and sends it back to the image forming unit in a reversed state to receive a copy on the back side; The copying auxiliary means includes a switching gate section that switches the paper feeding direction between the paper ejection section and the auxiliary means, a switchback section that switches the leading edge and trailing edge of the copy paper placed in the receiver and sends it out, and a switchback section that switches the copy paper sheet after switching back It consists of a return section that returns the copy paper to the image forming section, and a reversing section that reverses the copy paper returned to the image forming section and sends it back to the image forming section in good condition. The copying means is driven intermittently for a fixed amount each time continuous copying is performed, and each copying paper after surface copying is sequentially inserted into the double-sided copying auxiliary means, and in the process of returning it to the image forming section, the above-mentioned return is performed. If the paper is returned in an overlapping state with misalignment due to one drive amount, and the copy paper after the first front copy reaches the specified return position, the paper after the front copy that is stocked in the return process is A double-sided copying machine characterized in that each copy sheet is sequentially sent back to an image forming section so that the back side can be continuously copied.