JPH0415665A - Image forming device - Google Patents

Abstract

PURPOSE:To shorten a carrying path for refeeding a sheet and to eliminate the need of a by-pass carrying path by refeeeding a transfer sheet whose one- surface is completely transferred without being stacked on a stacking means, when the set value of a number of both surface transfer sheets setting means is one, that is, the number of the transfer sheets whose both surface is transferred is one. CONSTITUTION:A number of sheets setting part 102 is provided on a controller 101, and the number of the transfer sheets which are fed from a manual tray 35 to a photosensitive body by the tenkey 34b of an operating panel 34 and whose both surfaces have the transfer of a developed image is set as the set value. When the set value is one, that is, the number of sheets whose both surfaces are transferred is one, the transfer sheet whose one surface is completely transferred and which is ejected from a fixing roller is directly fed to a switch back carrying unit 61 without being stacked on the manual tray 35. Thus, the carrying path for refeeding the sheet can be shortened when both surfaces are transferred, and further, the by-pass carrying path can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image forming apparatus, and more particularly to a transport path for transfer paper in the apparatus.

[Conventional technology]

In general, in image forming devices such as copying machines, as their transfer functions become more diverse, they are not limited to just one-sided transfer of transfer paper, but also require double-sided transfer or composite transfer. Various measures have been taken to correspond to the above-mentioned various transfer forms.

As a conventional image forming apparatus of this type, the one described in Japanese Patent Application Laid-open No. 111955/1983 as shown in FIG. 12 is known, for example. In FIG. 12, reference numeral 1 indicates the paper feed strength, and the transfer paper 2 placed in the paper feed cassette 1 is conveyed by the paper feed roller 3, and the paper feed timing is controlled by the registration roller 4. Thereafter, the paper is fed to the photosensitive drum 5.

On the other hand, a scanning optical system 6 is provided on the surface of the photoreceptor drum 5.
An electrostatic latent image of the document 8 on the document table 7 is formed by
As the photoreceptor drum 5 rotates clockwise in the figure, the electrostatic latent image on the photoreceptor drum 5 is developed by the developer 9. As described above, the developed image on the photosensitive tram 5 is transferred to the transfer paper 2 supplied to the photosensitive drum 5, and after passing through the fixing device 10 and fixing the developed image, the discharge roller The paper is conveyed by the group 11 and discharged onto the paper discharge tray 12 . Note that reference numeral 13 is a conveyor belt that conveys the transfer paper 2 after transfer to the fixing device 10.

The above is a case of single-sided transfer of the transfer paper 2, but below, a case of double-sided transfer of the transfer paper 2 will be explained.

That is, as described above, the transfer paper 2 that has been transferred on one side and is discharged from the fixing device 10 is guided by the first flapper 14 that has been switched downward, is conveyed upward along the reversing wheel 15, and is then discharged. The sheet is conveyed downward by the lower pair of discharge rollers lla and llb of the roller group 11, and placed on the intermediate tray 16 with the transfer surface facing upward. Further, when the number of transfer sheets 2 sequentially accumulated on the intermediate tray 16 reaches a predetermined number, the transfer sheets 2 are sequentially transferred to the registration rollers 4 from the uppermost one by the paper refeed roller 17 and the conveyance roller 18.
The paper is fed to the photoreceptor drum 5 via the . At this time, the transfer paper 2 fed from the intermediate tray 16 to the photosensitive drum 5 is transferred to the paper re-feed roller 17,
Of course, when passing through the conveyance roller 18, the front and back sides are reversed. In this conventional example, when the number of sheets of transfer paper 2 to which double-sided transfer is performed is one, the second flanper 19 of the intermediate tray 16 is switched downward, and the transfer paper 2 on which one-sided transfer has been performed is bypassed. The paper is directly fed to the transport roller 18 via the transport path 20, and the transfer paper generated when the transfer paper 2 is once placed on the intermediate 1-lay 16 and then re-fed. This is to prevent jamming or skewing of the number 2.

[Problem to be solved by the invention]

However, in such a conventional image forming apparatus, when the number of sheets of transfer paper 2 to be transferred on both sides is one,
Since the transfer paper 2 was fed to the photoreceptor drum 5 via the bypass conveyance path 20, the conveyance path for refeeding the paper became long and the processing speed decreased, and the bypass conveyance path 20 was also installed. The need to do so increases the manufacturing cost of the device, and furthermore, there is a problem in that it is not possible to save space within the device.

[Purpose of the invention]

The present invention has been made against the background of the problems of the prior art as described above, and the set value of the double-sided transfer sheet number setting means is 1.
In the case of , that is, when the number of sheets of transfer paper to which double-sided transfer is to be performed is one, the conveyance path for re-feeding is shortened by re-feeding the transfer paper on which one-sided transfer has been performed without stacking it in the stacking means, Furthermore, by eliminating unnecessary bypass conveyance paths,
It is an object of the present invention to provide an image forming apparatus that has a high processing speed, and at the same time can reduce manufacturing costs and save space within the apparatus.

[Structure of the invention]

In order to achieve the above object, the present invention includes an image carrier, an image forming means for forming a latent image on the image carrier and developing the latent image to form a developed image, and a transfer paper that has not been transferred. a transfer paper mounting means for placing the transfer paper on the transfer paper mounting means; a paper feeding means for feeding the transfer paper of the transfer paper mounting means to the image carrier; and a paper feeding means for transferring the developed image on the image carrier to the transfer paper fed to the image carrier. a transfer means, a fixing means for fixing the developed image transferred to the transfer paper, and a reversing means for transporting the transfer paper on which the developed image is fixed by the fixing means along a conveyance path and reversing the front and back of the transfer paper; The transfer sheet is configured to be able to manually feed the transfer paper, stacks the transfer paper that has been transferred on one side and is fed from the reversing means, and conveys the transfer paper along a conveyance path that constitutes a part of the conveyance path of the reversal means; comprising a stacking means for feeding paper to the image bearing member, and a double-sided transfer sheet number setting means for setting the number of sheets of transfer paper fed from the stacking means to the image bearing member and on which a developed image is transferred to both sides as a set value, In an image forming apparatus that repeatedly performs double-sided transfer of transfer paper in accordance with a set value of a double-sided transfer number setting means, when the set value of the double-sided transfer number setting means is 1, transfer papers that have been transferred on one side are stacked. This feature is characterized in that it does not stack on the means.

Hereinafter, the present invention will be specifically explained based on examples. 1 to 11 are diagrams showing an embodiment of an image forming apparatus according to the present invention.

First, the configuration will be explained. In FIG. 1, reference numeral 31 is a copying machine main body as an image forming apparatus, and the copying machine main body 31
displays a document placement table 32 provided at the top, a paper ejection tray 33 on which transferred transfer paper ejected from the inside is placed, a copy start button 34a, a numeric keypad 34b, and the number of sheets set and the occurrence of a jam. An operation panel 34 having a display section 34C, etc., a manual feed tray 35 attached to the front side of the copying machine main body 31 so as to be openable and closable, a mounting section 36 for mounting a toner cartridge and a discharge toner tank (not shown), and transfer paper. When replenishing, etc., the fulcrum parts 37a, 37
The door unit 37 is opened and closed centering on b.

Note that the manual feed tray 35 serves as a cover for the copying machine body 31 when it is normally closed, and when it is opened toward the front in the figure, it becomes a tray for almost horizontal manual paper feed, and guides transfer paper that is manually fed from the outside. (Details will be explained later).

In FIGS. 2(a) and 2(b), reference numeral 38 is a recording section, and the recording section 38 includes automatic paper feed sections 39A, 39B, 39
The transfer paper P is automatically fed from one of the transport paths 40 through the transport path 40. Automatic paper feed section 39A-3
9C is a paper feed cassette 41 in which the untransferred transfer paper P is placed with the paper surface facing up and down, and a plurality of paper feed cassettes 41 placed on the paper feed cassette 41, which will be described with reference numerals A and BSC omitted, respectively. A pickup roller 42 is attached to the paper feed cassette 41 so as to pick up the uppermost transfer paper P among the transfer papers P of The paper feed roller 43 is housed in the door unit 37 shown in the figure. As mentioned above, the paper feed rollers 43A to 43C are housed in the door unit 37 shown in FIG. 1, and therefore, in FIG. When opened to the front side, the paper feed force centers 41A to 41C can be pulled out together with the pickup rollers 42A to 42C in the direction of arrow A in FIGS. 2(a) and 2(b), allowing transfer paper P to be replenished or replaced. can be easily done. In addition, the paper feed cassettes 41A to 41A of the automatic paper feed sections 39A to 39C described above
41C constitutes a transfer paper placing means for placing an untransferred transfer paper P, and pink up rollers 42A to 42C and paper feed rollers 43A to 43C move the transfer paper P of the above-mentioned transfer paper placing means to the conveyance path 40. This constitutes a paper feeding unit that conveys the paper through the photoreceptor drum 44 as an image carrier, which will be described later.

On the other hand, the above-mentioned recording section 38 is composed of the above-mentioned photosensitive drum 44 as an image carrier, an electrostatic charger 45, an exposure optical system 46, and a development system 47, although a detailed explanation will be omitted since it has a well-known configuration. An image forming unit 48, a transfer charger 49 that transfers the developed image formed on the photoreceptor drum 44 by the image forming unit 48 to the untransferred transfer paper P fed by the automatic paper feeding sections 39A to 39C, and an automatic transfer charger 49. The transfer paper P fed from the paper feed units 39A to 39C is conveyed from a predetermined position to the transfer charger 49, and the developed image is transferred by the registration roller pair 50 that controls the timing of conveyance of the transfer paper P and the transfer charger 49. a fixing roller 51 that heats the transferred transfer paper P to fix the developed image, and constantly rotates in the paper ejection direction to eject the fixed transfer paper P;
It is composed of a conveyor belt 52 and the like that conveys the transfer paper P from the transfer charger 49 to the fixing roller 51. Here, among the components of the recording section 38 described above, the image forming unit 4
8 exposes the photoreceptor drum 44 charged by the charger 45 with original reflected light containing image information by an exposure optical system 46 including a light source and a first and second scanner 53, 54 including a plurality of mirrors; After forming a latent image on the photoreceptor drum 44, the latent image is developed by a developing system 47 to form a developed image (developed image) on the photoreceptor drum 44. Further, the registration roller pair 50 is configured to rotate intermittently in order to send out the transfer paper P in synchronization with the developed image on the photosensitive drum 44. Note that it is preferable to provide a carry-in roller that constantly rotates in the carry-in direction at the center of the transfer paper P in the width direction of the transfer paper P just before the pair of registration rollers 50 to prevent the transfer paper P from skewing. The image forming unit 48 described above forms an image forming means that forms a latent image on the photosensitive drum 44 as an image carrier and develops the latent image to form a developed image, and the transfer charger 49 forms a developed image. The photosensitive drum 44 is attached to the transfer paper P fed to the photosensitive drum 44 as an image carrier.
constitutes a transfer means for transferring the developed image. Further, the fixing roller 51 constitutes a fixing means for fixing the developed image transferred to the transfer paper P. Note that the copying machine main body 31 can be separated into an upper recording section 38 and a lower automatic paper feeding section 39, and FIG. 2(b) shows the recording section 38 opened by rotating the upper part of the copying machine main body 31. Indicates the condition.

Here, FIG. 3 is an enlarged view of the main part of section m in FIG. 2(a), and the configuration of the switch hack conveyance unit 61 will be explained based on FIG. 3. That is, the automatic paper feeding sections 39A to 39C and the registration roller pair 50 shown in FIG. 2(a)
In FIG. 3, the conveyance path between
and a switchback conveyance path 62,
The conveyance path 40 carries the transfer paper P conveyed by the relay roller 63.
The switch hack transport path 62 is provided with the switch hack transport unit 61 described above. Specifically, the switchback conveyance unit 61 is made of an elastic body (
For example, Mylar), the double-sided feed channel 40.6
A backflow prevention member 65 is supported in a cantilever manner by a guide plate 64 at the connecting portion of No. 2 in a state that only allows transport of the transfer paper P from the transport path 40 to the switch bank transport path 62. Transfer paper P when passing through member 65
A relay sensor 66 is installed to detect the leading and trailing edges of the transfer paper P and is installed to detect that the transfer paper P is carried into the switch hack conveyance path 62, and a relay sensor 66 is installed in the switch hack conveyance path 62 to detect the presence or absence of the transfer paper P. switch eight sensor 67,
A friction pad 68 made of foamed polyurethane rubber or the like and placed approximately in the center of the switch hack conveyance path 62, and a friction pad 68 made of, for example, Nosolesox-based rubber and vertically opposed to the friction pad 68 with the switch hack conveyance path 62 in between. a contact/separate roller 69 that rotates in forward and reverse directions to switch the conveyance direction of the transfer paper P;
abuts on and separates from the friction band 68 to transport and stop the transfer paper P on the friction band 68.
It is driven and swung by the approaching/separating solenoid mechanism 70 shown in the figure and a solenoid (not shown), and guides the leading edge of the transfer paper P sent out to the registration roller pair 50 side by the approaching/separating roller 69 in the vicinity of the approaching/separating roller 69. A clamper 71 that can be clamped between the plate 64 and the clamper 71 is provided. The switch bank conveyance unit 61 configured in this way includes the automatic paper feed sections 39A to 39C shown in FIG.
The transfer paper P fed in the first conveyance direction shown by the arrow D1 through the conveyance path 40 is carried into the switch bank conveyance path 62 by normal rotation of the contact/separation roller 69 (clockwise rotation in the figure). By reversing the approaching/separating roller 69, the transfer paper P is ejected from the switch hack conveyance path 62 in the second conveyance direction indicated by the opposite arrow D2 while maintaining the orientation of the paper surface with respect to the direction. It is supplied to a pair of rollers 50. Note that, hereinafter, the reversal of the conveying direction of the transfer paper P in the switch hack conveying unit 61 will be simply referred to as a switch hack.

As described above, the contact/separate solenoid mechanism 70 moves the contact/separate roller 69 up and down to convey and stop the transfer paper P on the friction band 68, and as shown in FIG. A bracket 73 supports the solenoid 72 that moves the solenoid 72 and the approaching/separating roller 69, and the bracket 73 is supported at the lower end in the figure, and the lower end is rotatably supported on the frame 31a of the copying machine main body 31 via a support shaft 74. is,
Furthermore, it consists of an arm member 75 whose upper end is connected to the protruding end of the plunger 72a, and a spring 76 interposed between the upper end of the arm member 75 and the above-mentioned frame 31a. Then, when the solenoid 72 is OFF,
Since the plunger 72a is free in the axial direction, the arm member 75 rotates clockwise in the figure around the support shaft 74 due to the biasing force of the spring 76, and moves the contact/separation roller 69 upward to move the friction pad 68. separate from On the other hand, when the solenoid 72 is turned on, the plunger 72a is driven by the solenoid 72 and moves to the left in the figure, the arm member 75 rotates counterclockwise in the figure about the support shaft 74, and at the same time the approaching/separating roller 69 is moved downward to come into contact with the friction pad 68, and the contact/separation roller 69 is rotated in forward and reverse directions by a stepping motor (not shown) or the like. Further, the above-mentioned backflow prevention member 65, which is a component of the switchback conveyance unit 61, curves upward in FIG.
0 into the switchhuck conveyance path 62, and when the conveyance of the transfer paper P into the switchhuck conveyance path 62 is completed, the transfer paper P returns to its initial position due to its elastic force to prevent the transfer paper P from flowing backwards, and the transfer paper P It has a function to prevent the paper from folding and jamming when the switch is hacked.

On the other hand, in FIG. 2, on the downstream side of the fixing roller 51,
A separation claw 81, a paper discharge sensor 82, and a paper discharge switching claw 83 are provided, and the separation claw 81 has a function of peeling off and separating the transfer paper P from the fixing roller 51 with the tip of the claw brought close to the fixing roller 51. The paper ejection sensor 82 is connected to the fixing roller 51
The passage of the transfer paper P and the presence or absence of the transfer paper P are detected on the exit side of the transfer paper P, and paper discharge information is output to a controller 101, which will be described later. On the other hand, the paper ejection switching pawl 83 is driven by a solenoid or the like (not shown), and in the case of one-sided transfer of the transfer paper P, is switched to the position shown by the imaginary line in the figure, and the ejection switching claw 83 switches the transfer paper P ejected from the fixing roller 51. The sheet is guided to the sheet discharge tray 33 through the single-sided sheet discharge path 84. Further, in the case of double-sided transfer, the paper discharge switching claw 83 is switched to the position shown by the solid line in the figure, and the transfer paper P discharged from the fixing roller 51 is transferred to the double-sided paper refeed path 83.
5 to the aforementioned conveyance path 40. Further, the duplex paper refeed path 85 is partially constituted by the manual feed tray 35 in a closed state, and as shown by the imaginary line in FIG. 2, when the manual feed tray 35 is opened in the direction of arrow B in the figure, , the lower part of the double-sided paper feed path 85 becomes a manual paper feed path. Specifically, the double-sided paper refeed path 85 is connected to the manual feed tray 3.
5 and a guide member 86 opposed thereto, the manual tray 35 normally functions as a conveying member in the closed state, and functions as a manual tray only when manual feeding is in the open state. Furthermore, as shown in FIGS. 2 and 5, at the bottom of the double-sided paper refeed path 85, there is a gathering roller 87 such as a sponge roller, and a pair of jogger fences 88A, 88.
8B, tip stopper 89, calling roller 90, paper feeding roller 9
1 and a tray sensor 92 are installed. and,
The transfer paper P discharged from the fixing roller 51 and entered into the double-sided paper refeeding path 85 is moved by a shifting roller 8 that constantly rotates in the paper refeeding direction.
7. Stacked in position by jogger fences 88A, 88B and tip stopper 89, calling roller 90
Then, the paper is fed to the conveyance path 40 again by the paper feed rollers 91. The tray sensor 92 detects the presence or absence of the transfer paper P stacked in front of the leading end stopper 89 and the paper width during double-sided transfer of the transfer paper P, and detects that the transfer paper is inserted into the manual tray 35 during manual transfer. Further, an opening/closing sensor 93 is provided on the upper side of the double-sided sheet refeeding path 85, and the opening/closing sensor 93 detects opening/closing of the manual tray 35.

Based on the detection signal of the opening/closing sensor 93, the manual feed tray 35 is locked so as not to be opened by a tray lock (not shown) when refeeding the transfer paper P stacked in the double-sided paper refeed path 85. In addition, each of the above-mentioned members,
The shifting roller 87 of the device can be swung by a solenoid or the like, and the transfer paper P in the double-sided paper refeed path 85 can be moved as necessary.
It has a function of bringing the leading edge of the transfer paper P into contact with the leading edge stopper 89 and aligning the longitudinal direction of the transfer paper P,
The jogger fences 88A and 88B are driven by a stepping motor or the like in the paper width direction when the transfer paper P is stacked, and have the function of aligning the width direction of the transfer paper P. 88
B causes the transfer paper P to be transferred to the double-sided paper refeed path 85 as described above.
Stacked in place within. In addition, the tip stopper 89
can be swung as shown by the arrow in Fig. 5 by a solenoid, etc., and when the transfer paper P is stacked, it functions as abutment for the transfer paper P as described above, and serves for paper refeeding and manual paper feeding. In some cases, it has a function of tilting forward and guiding the transfer paper P in the paper feeding direction. Furthermore, in the case of manual paper feeding, the jogger fences 88A and 88B are fixed at a distance corresponding to the paper width of the transfer paper P that is manually fed,
It functions as a guide for the transfer paper P. Note that the above-mentioned shifting roller 87, jogger fences 88A, 88B, and tip stopper 89 constitute the stacking section 94 of the manual tray 35, and the calling roller 90 and paper feeding roller 91 constitute the paper refeeding section 95 of the manual tray 35. .

As described above, in the case of double-sided transfer of the transfer paper P, the transfer paper P discharged from the fixing roller 51 is switched to the position shown by the solid line in FIG. 2(a). The paper is guided to the double-sided paper refeeding passage 85 by the paper ejection switching claw 83, and after being stocked in the two-sided paper refeeding passage 85, it is conveyed by the paper feed roller 91 and double-sided paper is recycled on the upstream side of the relay roller 63. The paper is fed to the conveyance path 40 that merges with the paper feed path 85 . Then, the transfer paper P fed to the conveyance path 40 is
In FIG. 3, the relay roller 63 transports the switch hack transport path 62 in the first transport direction indicated by the arrow D1.
The paper is further conveyed by the contact/separation roller 69 along the switch hack conveyance path 62 in the second conveyance direction shown by the arrow D2, and then fed to the photosensitive drum 44 shown in FIG. 1 via the registration roller pair 50. It is papered. At this time, the fixing roller 5
The transfer paper P discharged from 1 rotates approximately 180° in a loop along the double-sided paper refeeding path 85, and is therefore stocked with its front and back reversed relative to the photoreceptor drum 44. The paper is conveyed to the switch hack conveyance path 62 while being inverted. Then, the transfer paper P is conveyed by a contact/separation roller 69 to a pair of registration rollers 50 and placed on a photosensitive drum 44.
The paper is fed to the photosensitive drum 4 by the transfer charger 49.
The developed image No. 4 is transferred to the untransferred back side, and the double-sided transfer of the transfer paper P is completed. Furthermore, transfer paper P on which double-sided transfer has been completed
Needless to say, the sheet passes through the fixing roller 51, is guided by the sheet discharge switching claw 83 which has been switched to the position shown by the imaginary line in FIG. 2(a), and is discharged onto the sheet discharge tray 33.

That is, in this embodiment, the paper ejection switching claw 83 and the double-sided paper refeed path 85 transport the transfer paper P on which the developed image has been fixed by the fixing roller 51 as a fixing means, and turn the transfer paper P upside down. The reversing means constitutes a reversing means, and at the same time, the reversing means has a double-sided paper refeeding path 85 as a conveyance path along which the transfer paper P on which the developed image is fixed is conveyed.

Furthermore, the above-mentioned manual feed tray 35 is configured to be able to manually feed the transfer paper P, and in the closed state stacks the transfer paper P of the single-sided transfer method fed from the above-mentioned reversing means, and also transports the transfer paper P. Double-sided paper refeed path 85 as a path
This constitutes a stacking means that conveys the paper along the same direction and feeds the paper to the photosensitive drum 44 as an image carrier. As described above, the double-sided paper refeeding path 85 has the functions of a reversing means and a conveying path for the stacking means. Therefore, in this embodiment, the conveying path of the stacking means is the conveying path of the reversing means. It forms part of the route.

Here, FIG. 6 is a schematic diagram when the contact/separation roller 69 of the switch bank conveyance unit 61 switches back the transfer paper P. In the figure, the transfer paper P conveyed by the contact/separation roller 69 and the contact/separation roller The friction coefficient of 69 is μ1, Fig. 2 (a)
Here, the friction coefficient between the transfer paper P2 clamped by the clamper 71 and the friction pad 68 is μ1, and the friction coefficient between the transfer papers P, P, and P2 is μ2. The transfer sheets identified by the symbols P1 and P2 in the figure will be explained in detail in the explanation of the function in the next section, but Pl is the transfer sheet to be conveyed to the pair of registration rollers 50 in FIG. In FIG. 3, P2 is conveyed by a relay roller 63, inserted between the transfer paper P1 and the friction pad 68, and further clamped by a clamper 71 and placed in the switch hack conveyance path 62. Showing paper. Then, when the relationship μm〉μm〉μ2 holds between the above-mentioned friction coefficients, the transfer paper P
The transfer paper P1 can be conveyed by the contact/separation roller 69 while the transfer paper P1 is held on the friction pad 68 in a standby state. Therefore, it is necessary to select the materials of the contact roller 69 and the friction band 68 in accordance with the material of the transfer paper P, and in this embodiment, 0.7>μm>0
．． 4, so μm〉1゜6.1.2〉μr〉1.0
The approaching/separating roller 69 and the friction pad 68 are respectively formed of materials that satisfy the following.

FIG. 7 shows drive units 38a, 39a, and 61a that respectively drive each member and device constituting the recording unit 38, automatic paper feed unit 39, switch hack transport unit 61, stack unit 94, and paper refeed unit 95. , 94a, 95a, separation claws 81, and paper ejection switching claws 83, respectively, and a controller 101 to which these drive parts are connected. 66, switch hack sensor 6
7, the paper ejection sensor 82 and the opening/closing sensor 93 are connected,
Signals from each of these sensors are input so that the members and devices in each section mentioned above operate accurately. The controller 101 is provided with a sheet number setting section 102, and the sheet number setting section 102 is operated by the ten key 34b of the operation panel 34 shown in FIG. The number of sheets of transfer paper P fed to the drum 44 is set as a set value, and the number setting section 102 also controls the recording section 38 via the controller 101.
, automatic paper feed section 39, switch pack transport unit 61,
A signal is output to the separation claw 81, paper ejection switching claw 83, stack section 94, and paper refeed section 95, and the transfer paper P is output in accordance with the set value.
Both sides of the image are transferred repeatedly. Further, when the setting value set in the sheet number setting unit 102 is 1, the transfer paper P that has been transferred on one side and discharged from the fixing roller 51 is directly fed into the switchback conveyance unit without stacking it on the manual feeding tray 35. The paper is fed to the photosensitive drum 44 via the photosensitive drum 61. That is, the above-mentioned sheet number setting section 102 selects transfer sheets that are stacked on a manual tray 35 as a stacking means, are fed from the manual tray 35 to a photosensitive drum 44 as an image carrier, and a developed image is transferred onto both sides. It constitutes a double-sided transfer sheet number setting means for setting the number of sheets P as a set value, and further includes a sheet number setting section 10.
The configuration is such that when the setting value of 2 is 1, the transfer paper P on which one side has been transferred is not stacked on the manual feed tray 35.

Next, the effect will be explained. Note that FIGS. 8 to 11 are drawings in which the automatic paper feed section 39 and the photosensitive drum 44 are added to FIG. 3 in order to explain the operation of this embodiment, respectively, and FIG. - The operation of this embodiment will be explained based on FIG. It goes without saying that the functions of the following parts are controlled by the controller 101 shown in FIG.

First, based on the above-mentioned FIGS. 8 to 11, in the case of single-sided transfer of the transfer paper P, that is, in FIG. The paper is fed to the recording section 38 via the hack transport unit 61,
After forming a developed image on one side of the transfer paper P, the paper output tray 3
The case of discharging in step 3 will be explained. That is, in this embodiment, in the first stage of one-sided transfer, in FIG. 2(a), the developed image formed on the photoreceptor drum 44 by the image forming unit 48 is transferred to the untransferred transfer paper P. , when feeding the untransferred transfer paper P from the automatic paper feeding sections 39A to 39C to the photosensitive drum 44, the automatic paper feeding sections 39A to 39C
Transfer paper P supplied from 39C is conveyed to a predetermined position in a first conveyance direction with the paper surface facing up and down, and then the transfer paper P is conveyed with the paper surface facing upward and downward. The transfer paper P is conveyed to a pair of registration rollers 50 in a second conveyance direction in which the transfer paper P is held and retreated, and is held by the pair of registration rollers 50 until it is transferred by the transfer charger 19.

More specifically, in FIG. 1, before the copy start button 34a is turned on, the data in FIGS.
As shown in (e), the untransferred transfer paper P is fed to the switch-huck conveyance unit 61 and further waits in front of the pair of registration rollers 50. That is, in FIG. 8(a), one of the automatic paper feeding units 39A to 39C shown in FIG. -4IC
The uppermost sheet of the transfer paper P placed on the paper is conveyed to the relay roller 63 by the paper feed roller 43C, and when the leading edge of the transfer paper P is detected by the relay sensor 66, as shown in FIG. 8(b). , the contact/separation roller 69 is the friction pad 68
move away from Next, the leading edge of the transfer paper P is moved to the contact/separation roller 69.
When the roller enters the nip of the transfer paper P, the contact/separation roller 69 approaches the friction pad 68 and comes into contact with the transfer paper P, as shown in FIG.
) begins to rotate clockwise. When the rear end of the transfer paper P passes the backflow prevention member 65, the contact/separation roller 69 moves as shown in FIG.
), the transfer paper P is reversed and switch-hacked. Then, as shown in FIG. 8(e), the transfer paper P is conveyed by a carry-in roller (not shown), and stopped while being held in the nip of the pair of registration rollers 50, to perform standby for single-sided transfer.

Continuing, in FIG. 1, the copy start button 34a
is turned on, and the switch bank of the transfer paper P to be fed next is performed. This will be explained based on FIGS. 9(a) to 9(f).

In other words, as shown in FIG. 9(a), upon copy start, the next transfer paper P' placed on the paper feed center 41C is conveyed to the relay roller 63 by the paper feed roller 43C. Ru. On the other hand, the transfer paper P held by the pair of registration rollers 50 and waiting is conveyed to the photosensitive drum 44 side at a predetermined timing by the rotation of the pair of registration rollers 50, and after the transfer is completed, the transfer paper P is shown in FIG. 2(a). At this point, the image is sent to a fixing roller 51 . During this time, as shown in FIG. 9(b), when the leading edge of the transfer paper P' conveyed to the relay roller 63 is detected by the relay sensor 66, the approaching/separating roller 69 is separated from the friction pad 68. Next, when the transfer paper P' enters the nip of the contact/separation roller 69, the contact/separation roller 69 closes the friction pad 6.
8, comes into contact with the transfer paper P', and rotates clockwise in the figure as shown in FIG. 9(c).

Then, when the rear end of the transfer paper P' passes through the backflow prevention member 65, the approaching/separating roller 69 is reversed as shown in FIG. 8(d), and the transfer paper P' is switch-hacked.

At the same time, the paper feed roller 43C starts feeding the second transfer paper P'' after a predetermined time. Then, when the leading edge of the second transfer paper P'' is detected by the relay sensor 66, the paper feed roller 43C starts feeding the second transfer paper P'' in the same manner. As shown in FIG. 9(e), the contact/separation roller 69 separates from the friction pad 68, and this second sheet of transfer paper P'' continues to be conveyed by the relay roller 63, so that its leading edge touches the friction band 6B and the previous transfer. It gets in between the paper P'.

Next, the rear end of the previous transfer paper P' is placed on the registration roller pair 5.
0, the contact/separate roller 69 comes close to the friction pad 68 and rotates as shown in FIG. 9(f), and the second transfer paper P''
Starts switch bank operation.

In this way, the transfer paper P conveyed from the automatic paper feeding section 39 to the switchback conveyance unit 61 is switchhacked one after another in the switchback conveyance unit 61, and then transferred to the photoreceptor drum 44 via the registration roller pair 50.
As a result, one-sided transfer of the transfer paper P is performed continuously and the paper is discharged to the paper discharge tray 33. At this time, in FIG. 2(a), the lowermost automatic paper feeder 39C, which has been continuing to feed paper, is replaced, for example, by the upper automatic paper feeder 39C, as necessary.
B and a different size of transfer paper P may be supplied, and in this case, Fig. 10 and Fig.
This will be explained based on FIG.

In other words, in FIG. 10(a), the previous automatic paper feed section 39C shown in FIG. A transfer paper Pd having a different size from the transfer paper P is fed to the switch hack conveyance unit 61.

At this time, when the transfer paper P that was waiting in front of the registration roller pair 50 separates from the registration roller pair 50 due to the rotation of the contact/separation roller 69 and the rear end in the traveling direction is detected by the sui-nochi hasoku sensor 67, the clamper 71 is activated. At the same time, the approaching/separating roller 69 is reversed as shown in FIGS. 10(b) and 10(c), and the transfer paper P is held by the clamper 71 after a predetermined period of time. On the other hand, the paper feed roller 43B conveys the uppermost sheet of the transfer sheets Pd of different sizes stacked on the paper feed force center 41B to the relay roller 63. Next, when the leading edge of the transfer paper Pd is detected by the relay sensor 6G, the contact/separation roller 69 separates from the friction pad 68 to prepare for the entrance of the transfer paper Pd.

When the leading edge of the transfer paper Pd enters between the transfer paper P held by the contact/separation roller 69 and the clamper 71, the contact/separation roller 69 approaches the friction pad 68 and rotates as shown in FIG. 10(e). , the rear end of the transfer paper PdO is the backflow prevention member 65
When the transfer paper Pd passes through, the contact/separation roller 69 is reversed and the transfer paper Pd is switched back, as shown in FIG. 1O(f). Then, as shown in FIGS. 10(g) to 10(h), the paper feed roller 43B starts transporting the next transfer paper Pd after a predetermined time, and in the same way, transfer papers Pd of different sizes are sequentially switched be done. Here, the reason why another transfer paper Pd can switch hack on the transfer paper P clamped by the clamper 71 is because the relationship of the friction coefficients between them is μ,〉μ,〉, as explained in FIG. This is because it is μ2. In this case, the symbols P and Pd in FIG. 10 correspond to the symbols P2 and Pl in FIG. 6.

Clamp, resist''-' Then, as shown in FIGS. 11(a) to 11(c), the clamper 71 releases the transfer paper P, and the contact roller 6
9 rotates clockwise in the figure, the transfer paper P is separated from the clamper 71, and when the rear end of the transfer paper P is detected by the switch hack sensor 65, the clamper 71 rotates downward and the approaching/separating roller 69 rotates counterclockwise,
The transfer paper P reaches the nip between the pair of registration rollers 50 and stops, and waits for transfer.

Continuing, double-sided transfer of the transfer paper P will be explained.

In the stack and FIG. 2(a), after the recorded image is fixed by the fixing roller 51, the ejected transfer paper P is transferred to the duplex refeeding path by switching the ejection switching claw 83 to the duplex refeeding path 85 side. 85, and is conveyed by a shifting roller 87 until its tip abuts a tip stopper 89, and is stacked. Note that if the double-sided transfer mode is not in effect, the transfer paper P is discharged onto the paper discharge tray 33. Here, when a plurality of sheets of transfer paper P are stacked, the jogger fences 88A and 88B align the sides of the transfer paper P in conjunction with the stacking operation of one sheet at a time, and align the side of the transfer paper P in the lateral direction with respect to the paper refeeding direction. Align the resist. When the double-sided transfer mode starts, first, the leading end stopper 89 falls down, and the transfer paper P, which has been stacked at the paper re-feeding position after the single-sided transfer has been completed, is sent to the paper feeding roller 91 by the calling roller 90, and is separated one by one. and transported to the switch hack transport path 62.

At this time, the transfer paper P discharged from the fixing roller 51 rotates approximately 180 degrees in a loop along the double-sided paper refeeding path 85, and therefore is in a state where the front and back sides are reversed with respect to the photoconductor door J, 44. Stocked. Then, when refeeding, the transfer paper P is conveyed to the switch hack conveyance path 62 with the front and back sides reversed as described above, and is further switch hacked by the switch hack conveyance unit 61, so that in the recording section 38, It is possible to transfer the back side. The transfer paper P on which the reverse side transfer has been completed is discharged to the paper discharge tray 33 by the paper discharge switching claw 83 which has been switched to the paper discharge tray 33 side, and the series of double-sided transfer operations is completed.

In this embodiment, during double-sided transfer, the size of the transfer paper P stacked in the double-sided paper refeed path 85 is changed from A6 (postcard) to A4Y (Y is horizontal feeding), and LT (letter size).
-Y (however, the length is less than 216 dragons) and transfer paper of longer length (e.g. B4, Al-T, A3)
etc.) are transferred on both sides one sheet at a time, and are re-fed without being stacked in the both-side re-feed path 85. That is, in the case of double-sided transfer, most of the transfer paper P used is small in size up to A4, and when considering space saving in the copying machine main body 31, the paper P used is stacked in the double-sided paper refeed path 85. It is more preferable to set the size of the transfer paper P as described above.

Next, manual paper feeding using the manual tray 35 will be explained based on FIG. 2(a).

hand! In FIG. 2(a), when the tip of the manual tray 35 is rotated in the direction of arrow B in the figure and the manual tray 35 is opened horizontally as shown by the broken line, it can also be used for manual paper feeding. be able to. That is, when the manual feed tray 35 is opened as described above, this is detected by the opening/closing sensor 93 and the manual feed mode is set, the paper ejection switching claw 83 is switched to the paper ejection tray 33 side, and the double-sided transfer mode is automatically disabled. becomes. Then, the shifting roller 87 moves upward, the jogger fences 88A and 88B retreat to both sides, and the manually fed plural sheets of transfer paper P are stacked at the position where their leading ends abut against the leading end stopper 89. At this time, the trace sensor 92 provided in the jogger fences 88A, 88B shown in FIG. 5 detects the presence or absence of the transfer paper P and the paper width, and then
8B returns to the size position of the transfer paper P and aligns the sides of the stacked transfer paper P. Note that the jogger fences 88A and 88B may be operated manually. Then, the stacked transfer paper P is sent to the paper feed roller 91 by the pick-up roller 90 by the tip stopper 89 falling forward at the same time as paper feeding starts, and is separated and sent to the relay roller 63, and then transported to the switch bank. It is conveyed to the road 62.

The explanation of the operation during double-sided transfer described above is based on a case where there are multiple setting values set in the sheet number setting section 102 shown in FIG. In the embodiment, the setting value of the number setting section 102 is 1.
That is, when the number of sheets of transfer paper P subjected to double-sided transfer is one, the following operation is performed. In FIG. 2(a), the shifting roller 87 moves upward, and in FIG. The paper is not stacked on the tray 35, but is sent to the paper feed roller 91 by the pick-up roller 90, and fed as it is to the switch hack conveyance path 62 by the relay roller 63. Further, the transfer paper P is switch hacked by a switch hack conveyance unit 61 in a switch bank conveyance path 62, and is transferred to a pair of registration rollers 50.
After being transferred via
The double-sided transfer of the transfer paper P is completed.

As described in detail above, in this embodiment, the controller 101 is provided with the sheet number setting section 102, and the operation panel 34
Using the numeric keypad 34b, set the number of sheets of transfer paper that is fed from the manual tray 35 to the photosensitive drum 44 and on which the developed image is transferred to both sides. When the number of sheets of paper P is 1,
The transfer paper P discharged from the fixing roller 51 and having been transferred on one side is not stacked on the manual feed tray 35, but is directly fed to the switch hack conveyance unit 61. Therefore, during double-sided transfer, it is possible to shorten the conveyance path for paper refeeding, and furthermore, it is possible to eliminate unnecessary bypass conveyance paths in the conventional example. As a result, the processing speed during transfer can be increased, and at the same time the copying machine main body 3
It is possible to reduce manufacturing costs and save space within the copying machine main body 31.

〔effect〕

According to the present invention, a double-sided transfer sheet number setting means is provided, and when the setting value of the setting means is 1, that is, when there is one sheet of transfer paper to which double-sided transfer is to be performed, the transfer paper on which one-sided transfer has been performed is stacked in the stacking means. Since I try to refeed the paper without letting it
It is possible to shorten the conveyance path for paper refeeding and eliminate unnecessary bypass conveyance paths. Therefore, the processing speed targeted by the present invention is high, and at the same time, the manufacturing cost is reduced by a.
It is possible to provide an image forming apparatus that can reduce the amount of noise and save space within the apparatus.

[Brief explanation of drawings]

1 to 11 are diagrams showing one embodiment of an image forming apparatus according to the present invention, FIG. 1 is an external perspective view thereof, and FIGS. 2(a) and 2(b) are cross-sectional views showing its configuration. Figure 3 is an enlarged view of the main part of the section ■ in Figure 2 (a), Figure 4 is a configuration diagram of the solenoid mechanism that moves the approaching and separating rollers up and down, Figure 5 is a perspective view of the manual feed tray, Figure 6 is a schematic diagram for explaining the coefficient of friction between the transfer paper, the contact/separation roller, and the friction pad, Figure 7 is a bronch diagram showing the connection of the controller, each sensor, and each drive unit, and Figures 8 to 8. 11 each has the same explanation of its operation. FIG. 12 is a configuration diagram showing a conventional example. 35... Manual feed tray (stack means), 41
A, 41B, 41C... Paper feed cassette/1 (transfer paper @ placement means), 44... Photosensitive drum (image carrier), 48...
...image forming unit (image forming means), 49...
...Transfer charger (transfer means), ...Sheet number setting section (double-sided transfer number setting means) P...Transfer paper. agent

Claims (1)

[Claims] an image bearing member, an image forming means for forming a latent image on the image bearing member and developing the latent image to form a developed image, a transfer paper placing means for placing an untransferred transfer paper; a paper feeding means for feeding the transfer paper of the paper mounting means to the image carrier; a transfer means for transferring the developed image on the image carrier to the transfer paper fed to the image carrier; a fixing means for fixing the developed image;
a reversing means for conveying the transfer paper on which the developed image has been fixed by the fixing means along a conveyance path and reversing the front and back sides of the transfer paper;
The transfer sheet is configured to be able to manually feed the transfer paper, stacks the transfer paper that has been transferred on one side and is fed from the reversing means, and conveys the transfer paper along a conveyance path that constitutes a part of the conveyance path of the reversal means; comprising a stacking means for feeding paper to the image bearing member, and a double-sided transfer sheet number setting means for setting the number of sheets of transfer paper fed from the stacking means to the image bearing member and on which a developed image is transferred to both sides as a set value, In an image forming apparatus that repeatedly performs double-sided transfer of transfer paper in accordance with a set value of a double-sided transfer number setting means, the set value of the double-sided transfer number setting means is 1.
1. An image forming apparatus characterized in that, when the transfer paper has been transferred on one side, the transfer paper is not stacked on the stacking means.