JP3210725B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless belt which is wound and rotated by applying tension to a plurality of rollers which carry a toner image or transfer paper and transport it to the next process area, and one of the rollers. And a cleaning means for pressing the cleaning member against the surface of the endless belt to clean the surface, wherein the cleaning member is disposed opposite to the roller via an endless belt, and the end of the endless belt is opposed to the roller. And an image forming apparatus provided with a tape-shaped reinforcing member.

[0002]

2. Description of the Related Art Conventionally, endless belts used in image forming apparatuses include photosensitive belts and transfer belts in color image forming apparatuses. In this type of image forming apparatus, rubber-based, resin-film-based, and metal-based belt materials are used. In a color image forming apparatus, a resin film based on a transfer belt or the like, which has low elongation and a high electric resistance, is widely used. Is used.

The belt of such an image forming apparatus has a structure in which a belt shift restricting member is provided at an end of the belt to prevent the shift of the belt because image shift or the like occurs when the shift occurs, thereby deteriorating the image quality. are doing. However, when the belt shift regulating member is provided, particularly in the case of a resin film-based member, an end crack may occur due to stress concentration near the regulating member.

Accordingly, Japanese Utility Model Laid-Open No. 2-95070 discloses a reinforcing member 5 attached to an end of a belt 50 as shown in FIG.
It is described that the time until the occurrence of an edge crack is lengthened by sticking No. 1.

[0005]

However, when the reinforcing member 51 is adhered, a step 52 is formed on the belt 50. When the belt 50 is a hard and hardly stretchable belt such as a polycarbonate resin, there is a problem that a slight step such as a step 52 or an end crack is generated in a short time due to an edge or a burr of a roller corner. Was.

Further, as shown in FIG. 7, when the belt biasing force is large, the belt biasing regulating member 54 may ride on the roller 53 and be damaged. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which solves the above-mentioned conventional problems, suppresses belt cracks, prolongs the life of the belt, and prevents waving to stabilize the running property of the belt.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a method of applying a tension to a plurality of rollers which carry a toner image or a transfer paper and transport it to a next process area, and which are wound around and rotated. Endless belt and one of the rollers
And a cleaning means for pressing the cleaning member against the surface of the endless belt to clean the surface, wherein the cleaning member is disposed opposite to the roller via an endless belt, and the end of the endless belt is opposed to the roller. In the image forming apparatus in which a tape-shaped reinforcing member is provided, the roller is formed to have a width wider than the width of the endless belt, and a region where the reinforcing member faces has a smaller diameter than a central region. Is provided, and a contact area of the cleaning member with the endless belt reaches an area where the reinforcing member faces.

According to the present invention, a belt shift regulating member is provided on a surface of the reinforcing member facing the roller,
In the step of the roller, another step having a smaller diameter than the step is provided in a region where the belt shift regulating member faces, and the contact area of the cleaning member with the endless belt is shifted toward the belt. It is effective if the regulating member reaches the opposing region.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing a color copying apparatus as an image forming apparatus according to the present invention, and FIG.
FIG. 3 is an enlarged view around an intermediate transfer belt. First, the configuration and operation of the color copying apparatus will be described.

A color image reading apparatus (hereinafter, referred to as a color scanner) 1 forms an image of a document 3 on a color sensor 7 via an illumination lamp 4, a mirror group 5, and a lens 6, and forms a color image of the document. Information, for example, Blue
(Abbreviated as B), Green (abbreviated as G), and Red (abbreviated as R) are read for each color separation light and converted into electrical image signals. The B, G, and R obtained by the color scanner 1
The color conversion processing is performed by an image processing unit (not shown) based on the color separation image signal intensity level of the color separation image. Black (hereinafter,
Bk), Cyan (same as C), Magenta
(Same, M) and Yellow (Same, Y) color image data are obtained.

A color image recording device (hereinafter, referred to as a color printer) 2 described below converts this into Bk,
Visualization of C, M, and Y is performed, and these are superimposed to form a four-color full-color image.

Next, an outline of the color printer 2 will be described. The writing optical unit 8 converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on the photosensitive drum 9 as a latent image carrier. .

The photosensitive drum 9 rotates in a counterclockwise direction as shown by an arrow. Around the photosensitive drum 9, a photosensitive member cleaning unit (including a pre-cleaning neutralizer) 10 and a neutralizing lamp 1 are provided.
1, charging device 12, potential sensor 13, Bk developing device 14, C
Developing device 15, M developing device 16, Y developing device 17, developing density pattern detector 18, intermediate transfer belt 19 as a carrier
And so on. Each developing device includes a developing sleeve 14 a, 15 a, 16 a, 17 a that rotates so that the developer faces the photoconductor 9 in order to document the electrostatic latent image, and a developing paddle that rotates so that the developer is pumped up and agitated. 14
b, 15b, 16b, and 17b, and toner concentration detection sensors 14c, 15c, 16c, and 17c of the developer. Order of developing operation (color image forming order)
Will be described below using examples of Bk, C, M, and Y. However, the image forming order is not limited to this.

When a copying operation is started, reading of Bk image data starts at a predetermined timing of the color scanner 1, and based on this image data, optical writing / latent image formation by laser light starts (hereinafter, Bk image). The electrostatic latent image based on the data is called a Bk latent image, and the same applies to C, M, and Y). In order to enable development from the front end of the Bk latent image, the rotation of the developing sleeve 14a is started before the front end of the latent image reaches the developing position of the Bk developing unit 14, and the Bk latent image is developed with Bk toner. Thereafter, the developing operation of the Bk latent image area is continued, but when the rear end of the Bk latent image has passed the Bk developing position, the developing operation is disabled. This is completed at least before the leading end of the C latent image based on the next C image data arrives.

The Bk toner image formed on the photoreceptor 9 is transferred onto the surface of an intermediate transfer belt 19 driven at a constant speed with the photoreceptor (hereinafter, transfer of the toner image from the photoreceptor to the intermediate transfer belt is referred to as belt transfer). Name). The belt transfer is performed by applying a predetermined bias voltage to the transfer bias roller 20 while the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other. In addition, on the intermediate transfer belt 19, Bk, C, M, and Y toner images sequentially formed on the photoconductor 9 are sequentially aligned on the same surface to form a belt transfer image by superimposing four colors, and then collectively on transfer paper. Perform transcription. The configuration and operation of the intermediate transfer belt unit will be described later.

In the photosensitive member 9, the process proceeds to the step C after the step Bk. At a predetermined timing, the reading of the C image data by the color scanner 1 starts, and the C latent image is formed by writing the laser light with the image data.

The C developing device 15 is moved with respect to its developing position.
After the trailing edge of the previous Bk latent image has passed and before the leading end of the C latent image has arrived, the rotation of the developing sleeve 15a is started to develop the C latent image with C toner. Thereafter, the development of the C latent image area is continued, but when the rear end portion of the latent image passes, the development is inactivated as in the case of the Bk developing device. This is also the next M
This is completed before the leading end of the latent image reaches.

In the steps M and Y, the operations of reading image data and forming / developing a latent image are the same as those in the steps Bk and C described above.

Next, the intermediate transfer belt unit will be described. The intermediate transfer belt 19 is wound around a drive roller 21, a belt transfer bias roller 20, a driven roller 21a, and a cleaning opposing roller 21b and given tension, and is driven and controlled by a drive motor (not shown) as described later. .

The belt cleaning unit 22 includes a brush roller 22a and a rubber blade 2 which are opposed to the cleaning opposing roller 21b with the intermediate transfer belt 19 interposed therebetween.
The second color, the third color, and the fourth color after the belt transfer of the BK image of the first color are formed by the cleaning member configured as the cleaning member 2b, the mechanism 22c for contacting and separating from the belt, and the like. During this time, the paper transfer unit 23 is moved by the contact / separation mechanism 22c to the paper transfer bias roller 23a,
It comprises a roller cleaning blade 23b, a mechanism 23c for contacting and separating from the belt, and the like. The bias roller 23 a is normally separated from the surface of the intermediate transfer belt 19, but the biasing roller 23 a takes a timing when the superimposed images of four colors formed on the surface of the intermediate transfer belt 19 are collectively transferred onto the transfer paper. A predetermined bias voltage is applied to the paper transfer bias roller 23a when pressed by 23c, and transfer to paper is performed, or at the same time, the transfer to paper is performed by contacting the surface of the photoconductor 9 charged by the charger 12 with the charger.

The transfer paper 24 is fed by a feed roller 25 and a registration roller 26 at the timing when the leading end of the four-color superimposed image on the intermediate transfer belt surface reaches the paper transfer position.

The intermediate transfer belt 19 can be moved in one of the following three modes after the belt transfer of the first color Bk toner image is completed up to the rear end. Operate by a combination of efficient methods according to the size (in terms of copy speed, etc.).

1) Constant speed forward system After the belt transfer of the Bk toner image, the forward movement is continued at a constant speed. 2. When the front end position of the Bk image on the surface of the intermediate transfer belt 19 reaches the belt transfer position at the contact portion with the photoconductor 9 again, the front end portion of the next C toner image on the photoconductor 9 side is just at that position. The image is formed with appropriate timing.

As a result, the C image is transferred onto the intermediate transfer belt 19 in a state of being accurately aligned with the Bk image. 3. After that, proceed to the M and Y image processes by the same operation,
A four-color superimposed belt transfer image is obtained.

4. Following the step of transferring the Y toner image belt for the fourth color, the image on the surface of the intermediate transfer belt
The color superimposed toner image is collectively transferred to the transfer paper 24 as described above.

2) Skip forward movement method When the belt transfer of the Bk toner image is completed, the photosensitive member 9
Then, the belt 19 is separated from the surface and skipped at a high speed in the forward direction as it is, and after moving a predetermined amount, the original forward speed is returned. As a result, the intermediate transfer belt 19 is brought into contact with the photosensitive member 9 again.

2. And B on the surface of the intermediate transfer belt 19
When the leading end position of the k image reaches the belt transfer position again, an image is formed on the side of the photoreceptor 9 at a timing such that the leading end of the next C toner image is exactly at that position.

As a result, the C image is transferred to the Bk image while being accurately positioned and superimposed on the Bk image. 3. Thereafter, the operation proceeds to the M and Y image processes by the same operation.
A color transfer belt transfer image is obtained.

The four-color superimposed toner image on the surface of the belt 19 is collectively transferred onto the transfer paper 24 at the same forward speed following the transfer step of the Y toner image belt for the fourth color.

3) Reciprocating (quick return) method When the belt transfer of the Bk toner image is completed, the photosensitive member 9
The belt 19 is separated from the surface, and the forward movement is stopped, and at the same time, the belt 19 is returned at a high speed in the reverse direction. The return is
After the front end position of the Bk image on the surface of the belt 19 passes through the position corresponding to the belt transfer in the reverse direction and further moves by a predetermined distance, it is stopped and put into a standby state.

2. Next, when the leading end of the C toner image on the photoconductor 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is started again in the forward movement direction. Further, the belt 19 is brought into contact with the surface of the photoconductor 9 again.

Also in this case, the belt transfer is performed under the condition that the C image is accurately overlapped with the Bk image on the surface of the belt 19. 3. Thereafter, the operation proceeds to the M and Y image processes by the same operation.
A color transfer belt transfer image is obtained.

4. Following the belt transfer process of the Y toner image for the fourth color, the toner is moved forward at the same speed without returning, and the four-color superimposed toner image on the surface of the belt 19 is collectively transferred to the transfer paper 24.

The transfer paper 24 on which the four-color superimposed toner image is collectively transferred from the intermediate transfer belt surface is conveyed to a fixing device 28 by a paper conveyance unit 27, and is controlled by a fixing roller 28a and a pressure roller 28b controlled to a predetermined temperature. The toner image is melted and fixed, and is carried out to the copy tray 29 to obtain a full color copy.

After the transfer of the toner image onto the transfer paper 24, the intermediate transfer belt 19 presses the cleaning unit 22 again by the contacting / separating mechanism 22c to clean the surface or at the same time to charge the photosensitive member 9 charged by the charger 12. The surface is brought into contact with the surface, and the surface is cleaned by the cleaning unit 22.

The surface of the photoreceptor 9 after the belt transfer is cleaned by the photoreceptor cleaning unit 10 and is uniformly discharged by the discharge lamp 11. After the toner image is transferred onto the transfer paper 24, the intermediate transfer belt 19 presses the cleaning unit 22 again by the contact / separation mechanism 22c, and at the same time, makes the cleaning unit 22 come into contact with the surface of the photoconductor 9 charged by the charger 12 so that the cleaning unit 22 To clean the surface.

At the time of repeat copying, the color scanner 1
The operation of (1) and the image formation on the photoconductor 9 are performed on the first sheet Y (4
The process proceeds to the second Bk (first color) image process at a predetermined timing following the (color) image process.

In the intermediate transfer belt 19, a second Bk toner image is formed in a region where the surface of the intermediate transfer belt 19 has been cleaned by the cleaning unit 22 following the batch transfer process of the first four-color superimposed image onto transfer paper. The belt is transferred. Thereafter, the operation is the same as that of the first sheet.

The transfer paper cassettes 30, 31, 32,
Transfer papers of various sizes are stored in 33, and are fed and conveyed in the direction of the registration rollers 26 at a timing from a storage cassette of the size paper designated by an operation panel (not shown). A manual feed tray 34 for OHP paper, thick paper, or the like may be provided.

The above is the description of the copy mode for obtaining four full colors. However, in the case of the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the case of the single-color copy mode, only the developing device of the color is set in the developing operation state until the predetermined number of sheets is completed, and the intermediate transfer belt 19 is moved to the photosensitive member 9.
The belt cleaner 22 is driven at a constant speed in the forward movement direction while being in contact with the surface, and the belt cleaner 22 performs the copying operation while being kept in contact with the intermediate transfer belt 19.

FIG. 3 is a partially enlarged sectional view of the intermediate transfer belt 19 and the cleaning opposing roller 21b. FIG.
, A reinforcing member 40 is adhered to at least one end of the intermediate transfer belt 19. As the reinforcing member 40, an adhesive tape based on a polyester film is generally used, but it is necessary to select a reinforcing member 40 having a higher mechanical strength than a belt material, particularly a material having high bending resistance. is there. Moreover, the thickness of the reinforcing member 40 is 25 to
A belt having a thickness of 200 μm is effective. If the belt is too thick, the rigidity of the belt becomes too high. In particular, where the diameter of the wound roller is small and the winding angle is large, the belt may be wavy and wrinkled.

By the way, the intermediate transfer belt 19 is made of a polycarbonate resin. In the case of a hard and less stretchable belt made of a polycarbonate resin or the like, end cracks due to slight steps of the belt, edges of the roller corners or burrs, etc. occur in a short time. As described above, there is a problem that such a problem occurs.

Therefore, in the present invention, the cleaning opposing roller 21b is provided with a step 41 in which the contact area b of the reinforcing member 40 has a smaller diameter than the central area a. This step 4
1 is formed at a height H1 equal to or greater than the thickness of the reinforcing member 40. Further, the step 41 has stripe-like scratches on the intermediate transfer belt 19 due to the edges and burrs of the corners 41a, thereby shortening the life of the intermediate transfer belt 19. Therefore, as shown in FIG. It is formed with a roundness of about 0.3 mm.

Thus, even if a step is formed on the intermediate transfer belt 19 by attaching the reinforcing member 40, the step on the intermediate transfer belt 19 is eliminated by providing the step 41 on the cleaning opposing roller 21b. The occurrence of edge cracks in the transfer belt 19 in a short time can be prevented. In the conventional example shown in FIG. 6, when the reinforcing member 51 is attached to the belt 50, an air space portion indicated by reference numeral 55 is formed. At this time, if the roller 53 is a cleaning opposing roller, the contact angle of the cleaning blade greatly affects the cleaning performance. Therefore, the allowable contact range of the cleaning blade is closer to the center than the air layer 55, and the belt roller The support unit becomes large, which causes problems in space and cost. Further, when the air layer 55 is formed, stress concentrates in the vicinity thereof, so that end cracks are easily generated. In the present invention, since an air layer cannot be formed, end cracks are unlikely to occur, and the allowable contact range of the cleaning blade may be within the contact area b of the reinforcing member 40. However, step 40
If the difference between the height H1 and the thickness of the reinforcing member 40 is too large,
Since the contact pressure of the blade becomes weak, the height H1 of the step 40 is increased.
The difference between the thickness of the reinforcing member 40 and the thickness of the reinforcing member 40 is preferably in the range of 0 to 0.05 mm. However, if there is room for cleaning, the difference may be ± 0.02 mm or the like.

In this embodiment, a belt shift regulating member 42 is adhered to the end of the intermediate transfer belt 19, and the contact area c of the belt shift regulating member 42 on the cleaning opposing roller 21 b is larger than the roller diameter of the step 41. Another step 43 having a small diameter is also provided. The step 43 is formed at a height H2 equal to or greater than the thickness of the belt deviation regulating member 42, and the corner of the step 43 is formed with a radius of about 0.05 to 0.3 mm.

FIG. 5 is a graph showing the time required for the belt to crack with respect to the width of the reinforcing member. Since a normal belt is a replacement part, if it is 10 mm or more, there is no practical problem. Further, by applying the crack to the surface side of the intermediate transfer belt 19, the crack generation time can be further lengthened.

In the intermediate transfer belt 19, assuming that the maximum image width of the transfer paper is e and the cleaning width of the cleaning blade is d, the maximum image width e, the central area a, the cleaning width d, and the contact area of the belt deviation regulating member 42 When the width is set wider in the order of the inner span of c, the inclination of the belt shift regulating member 42 when the belt shift is large can be reduced, and the belt life can be increased. Further, when the cleaning width is set to d ′ and set within the contact area c of the belt shift regulating member 42, the belt 4 is adjusted by the cleaning blade.
2 can be prevented from riding on the roller. By setting the width of the blade to be larger than the width of the restricting member, it is possible to prevent this riding. Conventionally, a separate member is provided to prevent the vehicle from running. However, since such a separate member is not required, space saving and parts reduction (cost reduction) are possible.

Although the roller providing the step has been described for the cleaning opposing roller 21b, it is preferable that the driving roller 21, the belt transfer bias roller 20, and the driven roller 21a be configured in the same manner.

[0049]

As described above, according to the present invention, by preventing the belt surface from waving and smoothing, the belt life is increased, the transfer stability is achieved by making the transfer pressure uniform, and the belt-drive roller adhesion force is increased. Since the running of the belt can be stabilized, good image quality can be obtained over a long period of time.
Furthermore, meandering of the belt can be reduced with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color copying apparatus.

FIG. 2 is an enlarged view around a photoconductor and an intermediate transfer belt.

FIG. 3 is a partially enlarged sectional view of an intermediate transfer belt and a cleaning opposing roller.

FIG. 4 is a partially enlarged explanatory view of a step corner portion in FIG. 3;

FIG. 5 is a graph showing a time required until a belt crack occurs with respect to a reinforcing member width.

FIG. 6 is a partially enlarged sectional view of a conventional belt and roller.

FIG. 7 is an explanatory diagram when the shift occurs.

[Explanation of symbols]

 19 Intermediate Transfer Belt 21b Cleaning Opposite Roller 40 Reinforcing Member 41 Step 42 Belt Deviation Control Member 43 Other Step

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-98284 (JP, A) JP-A-3-55565 (JP, A) JP-A-2-22903 (JP, U) JP-A-3-23 73541 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 5/02 B65H 5/00

Claims (2)

(57) [Claims] An endless belt that is wound and rotated by applying tension to a plurality of rollers that carry a toner image or a transfer sheet and convey it to a next process area;
And a cleaning means for pressing the cleaning member against the surface of the endless belt to clean the surface, wherein the cleaning member is disposed opposite to the roller via an endless belt, and the end of the endless belt is opposed to the roller. In the image forming apparatus in which a tape-shaped reinforcing member is provided, the roller is formed to have a width larger than the width of the endless belt, and a step in which a region facing the reinforcing member has a smaller diameter than a central region. Wherein the contact area of the cleaning member with the endless belt reaches an area where the reinforcing member is opposed to the image forming apparatus. 2. A belt shift regulating member is provided on a surface of the reinforcing member facing the roller, and the step of the roller has a diameter smaller than that of the step in an area where the belt shift regulating member faces. 2. The image forming apparatus according to claim 1, wherein another step is provided, and a contact area of the cleaning member with the endless belt reaches an area where the belt shift regulating member faces. apparatus.