JPH02232677A - Transfer device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of use in JT industry) The present invention relates to a transfer device for an image forming apparatus that employs an electrophotographic process. (Prior art) Image formation using electrophotographic processes such as copying machines! lt
In general, the developed image formed on the photosensitive drum (*carrier) is transferred onto transfer paper (transfer material) via a transfer device. Various types of such transfer devices have been proposed and put into practical use. For example, as shown in FIG. The transfer paper P, which is adsorbed and held by the holding sheet 101, is brought into contact with the photosensitive drum, and a corona discharge is applied from inside the holding sheet lot toward the photosensitive drum via a transfer charger, and the photosensitive drum There is one that transfers the developed image above onto transfer paper P. In this case, if a cylindrical holding sheet lot is brought into contact with a cylindrical photosensitive drum, generally a line contact will occur, and in one transfer, the transfer to the transfer paper P and the peeling of the transfer paper P from the photosensitive drum are performed at the same time. Not only does the transfer become extremely unstable, JQI often causes unevenness in the transferred image quality, and the transfer efficiency also deteriorates. For this reason, the holding sheet 1 of the photosensitive drum and transfer equipment is
01 needs to be brought into surface contact through the transfer paper P, and as shown in Japanese Patent Publication No. 63-34468, a suppressing means is disposed inside the holding sheet 101, and A device in which the holding sheet lot is deformed so as to protrude outward by a suppressing means so that the photosensitive drum and the holding sheet 101 come into contact with each other through the transfer paper P is widely used. (Invention or attempt to solve!!B) However, in the above conventional technology, the holding sheet 101 is free to deform in the vicinity of the supporting member lOO that fixes the holding sheet lOl of the holding sheet 101 and in other parts. Since the contact area between the holding sheet 101 and the photosensitive drum via the transfer paper P varies depending on the location. Therefore, the pressing force of the suppressing means may be insufficient on the transfer paper Pf disposed on the holding sheet 101 near the support member lOO, and sufficient surface contact of the transfer paper P with the photosensitive drum cannot be obtained, resulting in poor image quality. There was a drawback that (transfer omission) was more likely to occur.As a countermeasure, the holding sheet l. It may be possible to separate the transfer area of O1 from the support member 100, or it would be necessary to increase the external size of the holding sheet 101 in order to secure the transfer area, resulting in an increase in the size of the apparatus. Another possible measure would be to elastically connect one or both ends of the holding sheet 101 to the support member 100 via a tension spring or the like. The degree of freedom of movement of the holding sheet 101 in the circumferential direction is too large, resulting in color misalignment during multiple transfers.
Since it is not an easy task to attach it to the support member 100, if a skilled and dedicated worker is required, it may be necessary to attach the holding sheet 101 to the support member 100 while pulling the holding sheet 101 to take up the slack. Therefore, the tension of the holding sheet 101 varies depending on the location or depending on the operator, making it extremely difficult to set the pressing force by the suppressing means. The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a transfer device that is easy to manufacture, is small, and does not degrade in performance. (!!Means for solving the problem) In order to achieve the above object, the present invention. In a transfer device that holds a transfer material on a cylindrical outer surface, brings the transfer material into contact with an image-rejecting member, and transfers the developed image on the image-receiving member onto the transfer material, fixing devices are attached to both ends of the transfer device. At least one of the fixing members is configured to be swingable, and the pair of fixing members are arranged in close proximity to each other to form a cylindrical shape, and a flexible holding sheet that holds the transfer material on the outer surface of the cylinder; Both ends of the cylindrical part of the holding sheet are pulled in the circumferential direction from the inside to guide and support them, and the supporting member of the holding sheet is formed with an attachment part for the fixing member of this holding sheet, and the inner side of the holding sheet The image forming apparatus is characterized in that it has a suppressing means disposed in the image bearing member for deforming a part of the holding sheet outward to bring the holding sheet into surface contact with the image carrier via the transfer material. (Function) This is because the fixing member on at least one end side of the holding sheet is configured to be swingable and is attached to the supporting member. The holding sheet on the swingable end side can be freely deformed without being affected by the supporting member, and the supporting member simply expands the diameter of the cylindrical end of the cylindrical holding sheet from the inside and pulls it in the circumferential direction. Since it only provides guidance and support, the ends of the cylindrical holding sheet can also freely deform outward. Therefore, the holding sheet can be uniformly deformed outward by the suppressing means, and the transfer material held by the holding sheet can be brought into uniform surface contact with the image carrier. (Example) Examples of the present invention will be described below based on the attached drawings. First, with reference to FIG. 9 and FIG. 10, an outline of the double ffi forming operation of an image forming apparatus that employs a drum-shaped transfer device and is capable of color copying will be explained. In this image forming apparatus, a primary charger 2 uniformly charges a photosensitive drum l, which is an image rejection member rotating in the direction of the arrow in FIG. Only the image light corresponding to the image information is irradiated by an exposure means consisting of a device, etc.
An electrostatic latent image is formed on the photosensitive drum l. The electrostatic latent image is visualized as a toner image on the photosensitive drum l by, for example, a mobile developing device M4. The mobile developing device 4 includes a magenta color developer, a cyan color developer, a yellow color developer,
There are four current t-bases 4M, 4C, 4Y, and 4B that store the four colors of black developer separately, and a guide ( (not shown), a desired developing device is conveyed to a developing position facing the outer peripheral surface of the photosensitive drum 1, and the electrostatic latent image on the photosensitive tram 1 is developed. The toner image on the photosensitive drum 1 is transferred onto a transfer paper (transfer material) P, and the transfer paper P is moved while being held by a transfer device 5, which will be explained in detail later, and brought into contact with the photosensitive drum l. At this point, the toner image is transferred onto the transfer paper P by this transfer device M5. The transfer paper P is supplied to the transfer device 5 by the registration roller 6 in synchronization with the toner image on the photosensitive drum l, and after the transfer is completed, the photosensitive drum 1 is cleaned of residual toner on the surface by the cleaning device 3. The image is then submitted to the color image process again. The transfer device W15 has a cylindrical shape, and a part of the transfer tram 20 is in contact with the photosensitive drum 1, and the transfer paper P is fed through the registration roller 6, which applies an electric charge to the outer surface of the transfer drum 20. a transfer paper adsorption stage 21 for adsorbing the transfer paper, and a transfer charger 22 disposed inside the transfer drum 20 for transferring the toner image on the photosensitive drum 1 to the transfer paper P in contact with the photosensitive drum 1. JR is comprised of a pressurizing means 23 and the like for the transfer paper P that brings the transfer paper P in contact with the photosensitive tram l into surface contact with the photosensitive tram l to increase transfer efficiency and perform stable transfer to the transfer paper P. ．． That is, the transfer paper P attracted to the outer surface of the transfer drum 20 by the attraction means 21 of the transfer device 5 is transferred to the photosensitive drum 1.
When the transfer tram 20 rotates and is conveyed to the position,
The transfer charger 22 is brought into contact with the photosensitive drum 1 via the pressing means 23, and the M1th color toner image formed on the photosensitive drum 1, for example, a toner image developed by the magenta color developer 4M, is transferred to the transfer charger 22. The image is transferred onto the transfer paper P via the transfer paper P. Then, before the transfer paper P hits the photosensitive drum l again as the transfer drum 20 rotates, the photosensitive drum l
An electrostatic latent image is formed by the second color image light, and this electrostatic latent image is visualized as a black toner image by, for example, a black color developer 4B. Then, the toner image is transferred again to the transfer paper P, and the same operation is performed with the image light L.
When the number of toner images has been applied, the transfer paper P is separated from the transfer drum 20 by the separation charger 7 and conveyed to a fixing device (not shown), where the toner image is fixed. Here, as shown in FIG. lever 3l
and a spring member 32 that pulls the pressure lever 3l counterclockwise in the figure and presses the tip of the pressure lever 3 against the inner surface of the transfer drum 20.
The tip of the pressure lever 3l moves onto the transfer drum 2 according to the elastic force of the
A transfer material holding sheet 43, which will be described later, disposed on the outer surface of the photosensitive drum 1 is deformed so as to protrude outward to bring the transfer paper P into surface contact with the photosensitive drum l. Next, the transfer tram 20 of the transfer device M5 will be described in more detail according to FIGS. 1 to 5.
The transfer device 5 according to the ml embodiment of the present invention will be explained. The transfer drum 20, as shown in FIG.
As shown in FIG. 5, the transfer holding sheet 43 and the like are disposed in a cylindrical shape as shown in FIG. The transfer paper holding sheet 43 is made of an ET tra material, and as shown in FIG. Mounting parts 43A and 43B are provided. A fixing member 44 made of a band-shaped rigid body is attached to the attachment portion 43A at one end along the entire length of the transfer paper holding sheet 43, and the fixing member 44 has attachment screws 48. The holes 45, . . . for moving and storing the heads of the screws 48 are formed halfway through the transfer paper holding sheet 43 and the fixing member 44. It has been done. In addition, a band-shaped elastic member 46 made of foamed urethane, rubber, etc. is attached to the mounting portion 43B on the other end side to hold the transfer paper holding sheet 43.
The elastic member 46 and the transfer paper holding sheet 43 have seat holes 45, . It is provided. Further, a fixing member 47 is attached to the elastic member 46, which is made of a band-shaped rigid body and has screw holes formed in positions facing the seat holes 45, .
The thickness of the attachment parts at both ends of the is the same. Therefore, one end of the transfer paper holding sheet 43 can be rigidly fixed, and the other end can be fixed flexibly in accordance with the deformation of the elastic member 46. On the other hand, as shown in FIG. 4, the connecting plate 41 of the supporting member 42 also has a screw hole 41a for attaching the transfer paper holding sheet 43.
．． ... is formed. In order to attach the transfer paper holding sheet 43 to the support member 42, the transfer paper holding sheet 43 is wrapped around the short cylindrical ring 40 of the support member 42 in a cylindrical shape, and the transfer paper holding sheet 43 is wrapped around the short cylindrical ring 40 of the support member 42. After positioning the mounting parts 43A, 43B of the sheet 43 on the connecting plate 4l of the support member 42, insert the screws 48, . and screw them into the screw holes 41a, . . . of the connecting plate 4l. Here, as shown in FIGS. 2 and 43, the seat holes 45 at both ends of the transfer paper holding sheet 43, . screw hole 4
The relationship between rjj and distance jtfl between the transfer paper holding sheets 1a and 41a is 1. =1. +α (however α>
0), and the allowance length α in this formula is the amount by which a predetermined tension (tension state) is applied to the transfer paper holding sheet 43 when the transfer paper holding sheet 43 is attached to the support member 42. It is for giving. In determining this margin α, expansion and contraction of the transfer paper holding sheet 43 due to environmental changes are taken into consideration. Also, consideration has been given to prevent color misalignment from occurring during multiple transfers of the transfer paper P. That is, the transfer paper holding sheet 4
for. It is also possible to give a predetermined tension (tension state) to this transfer paper holding sheet 43 by attaching the contact portion with the short cylindrical rings 40, 40 to the short cylindrical rings 40, 40. However, in the present invention, this tensioning is abolished, and instead, the transfer paper holding sheet 43 is made to have a predetermined tension (tension state) by controlling the above-mentioned margin length α. By configuring the transfer drum 20 as described above, the work of assembling the transfer paper holding sheet 43 and the support member 42 becomes easy, and the work time can be shortened. Further, it becomes possible to uniformly apply a predetermined tension to the transfer paper holding sheet 43 without requiring skilled workers. In particular, since there is no adhesive or other attachment between the transfer paper holding sheet 43 and the short cylindrical ring 40, 40 of the support member 42, the transfer paper holding sheet 43 can freely move outward even in this vicinity. It is deformable. Furthermore, since the attachment parts 43A and 43B of the transfer paper holding sheet 43 are also provided with an elastic member 46 on one side, the transfer paper holding sheet 43 around the attachment part 43A can also be freely deformed. ing. For this reason, suppression. Transfer paper holding sheet 4 with 1,000 steps 23
There is almost no difference in the degree of freedom of deformation depending on the location, and transfer defects are less likely to occur, and the transfer paper holding sheet 4
3 can be used almost entirely for transfer, so the transfer tram 20 can also be made small, and the transfer device 5 as a whole can be made small. In this embodiment, the transfer paper holding sheet 43
The elastic member 46 is used only in the attachment part 43A on one end side, or may be used on the other end side, which makes the transfer paper holding sheet 43 more freely deformable. Since the entire area of the transfer paper holding sheet 43 can be used for transfer, the transfer device 2!5 can be further downsized. Next, a second embodiment of the present invention will be explained with reference to FIGS. 6 to 8. Components having the same functions as those in the first embodiment are given the same reference numerals in this embodiment as in the first embodiment, and their explanations will be omitted. The difference between this embodiment and the first embodiment is as shown in FIG. Transfer paper holding sheet 43
Fixing members 44.44 are attached to the mounting portions of both, and the transfer paper holding sheet 43 is attached via the fixing members 44.44.
is fixed to the connecting plate 4l of the support member 42, and 2
A rigid movable member 49 is connected to one fixed member 44 via a pin 49a, and one end of the transfer paper holding sheet 43 is attached to the movable member 49. Therefore, as shown in FIG.
9 can rotate around the pin 49a, the transfer paper holding sheet 43 can be freely deformed even in the vicinity of the fixing member 44. The same effect can be obtained by using the elastic member 46 as in the tJ41 embodiment. In addition, in this embodiment, the transfer paper holding sheet 43 is attached to the rigid movable member 49.
Since the transfer paper holding sheet 43 can be fixed in place, it is possible to prevent the transfer paper holding sheet 43 from waving or wobbling in this attachment part, and since the elastic member 46 is not used as in the first embodiment, the 8A elastic member 4
There is no elastic deterioration that is characteristic of 6. Also. As a modified embodiment of this embodiment, as shown in FIG.
At the same time, a block member 50 made of a rigid body is attached to the transfer paper holding sheet 43 near one of the fixing members 44 and 44 along the fixing member 44, and the fixing member 4
It is also possible to prevent waving, twisting, etc. of the transfer paper holding sheet 43 that tends to occur near the transfer paper holding sheet 43. In this embodiment, the moving member 49 and the block member 5
0 is provided only on one fixing member 44 side, but it is of course possible to provide it on both sides, and in this case the effect will be doubled. (Effects of the Invention) As is clear from the above description, according to the present invention, the holding sheet can be attached to the supporting member so as to generate a uniform tension, and the holding sheet can be prevented from deforming outward. hand. Since the holding sheet is configured so that it can be freely deformed outward by the pressing means even in the vicinity of the contact area between the holding sheet and the support member, almost the entire holding sheet can be used for transferring the transfer material. The device can be made smaller while maintaining performance. In addition, attachment of the holding sheet to the support member is easy, as it is only necessary to attach the holding sheet fixing member to the attachment part of the support member, and the holding sheet can be easily attached to the support member in a uniform state. , there will be no transfer defects.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a transfer paper holding sheet of a transfer device according to the first embodiment, Fig. 2 is a perspective view of a transfer paper holding sheet of the transfer device, and Fig. 3 is a side view of a transfer drum of the transfer device. Figure 4 is a perspective view of the support member of the transfer device, Figure 5 is a perspective view of the transfer paper holding sheet of the transfer device when it is deformed into a cylindrical shape, and Figures 6 to rIS8 are the second implementation. FIG. 9 is an enlarged partial cross-sectional view showing the state in which the transfer material holding sheet of the transfer device according to the example is attached to the support member, FIG. 9 is a cross-sectional view of the main parts around the image carrier of the image forming device, and FIG. Cross section, 11th
The figure shows the conventional technology. L... Photosensitive drum (image carrier), 5... Transfer device 23... Pressure means (suppressing means), 41... Connecting plate (attachment part), 42... Support member, 43 ...Transfer paper holding sheet (holding sheet), 4
6... Elastic member (fixing member), 49... Block member (fixing member), P... Transfer material. Patent Applicant Canon Inc. Representative Patent Attorney Ryo Yamashita Figure 1 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] In a transfer device that holds a transfer material on a cylindrical outer surface, brings the transfer material into contact with an image carrier, and transfers the developed image on the image carrier onto the transfer material, a fixing device attached to both ends of the transfer device is used. At least one of the members is configured to be swingable, the pair of fixing members are brought close together to form a cylindrical shape, and a flexible holding sheet holds a transfer material on the outer surface of the cylinder; Both ends of the cylindrical portion of the sheet are pulled in the circumferential direction from the inside to guide and support the sheet, and a supporting member of the holding sheet is formed with a mounting portion for the fixing member of the holding sheet, and a supporting member of the holding sheet is formed inside the holding sheet. 1. A transfer device comprising: a pressing means disposed to deform a part of the holding sheet outward to bring the holding sheet into surface contact with an image carrier via a transfer material.