JP2000098765A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent malfunction caused by such a state that foreign material, etc., stick on an intermediate transfer belt. SOLUTION: The device is provided with a hole 5h formed in the intermediate transfer belt 5a in order to detect the TOP position of an image, a patch 5i arranged in the hole 5h and a photointerrupter 5j for making the image pass through the hole 5h, besides, the device is provided with a cleaning means 5k for cleaning the foreign material heaped on the patch 5i and a container 5m for storing the foreign material 5n cleaned by the cleaning means 5k, and the container 5m is arranged on the upstream side of the cleaning means 5k in the moving direction R5 of the intermediate transfer belt 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic color image forming apparatus such as a color copying machine or a color printer, and more particularly to a color image forming apparatus having an intermediate transfer unit.

[0002]

2. Description of the Related Art In a color image forming apparatus using an intermediate transfer belt, an intermediate transfer body unit in which an intermediate transfer belt is stretched around a plurality of rollers is mounted on the main body of the image forming apparatus. After superimposing toner images of four colors of yellow, magenta, cyan, and black on the intermediate transfer belt (primary transfer), the toner images are collectively and secondarily transferred to a transfer material.

The intermediate transfer belt has a head position of an image,
That is, in order to detect the TOP position, a hole is formed in a corner or the like of the intermediate transfer belt, or a reflective material is attached.

However, foreign matters such as undeveloped developer and waste toner leaking from the developing device are scattered by the wind of the cooling fan inside the current color image forming apparatus. When this foreign matter adheres to the TOP position detecting portion of the intermediate transfer belt,
Since the TOP position cannot be detected, the above-described primary transfer and secondary transfer cannot be performed.

For this reason, some image forming apparatuses are provided with a means for cleaning foreign substances adhering to the detection unit of the TOP position. However, there is no container for collecting the cleaned foreign substances, or the position of the container is determined by the cleaning means. On the other hand, the foreign matter is scattered again because it is not on the upstream side of the intermediate transfer belt, and the cleaning effect is reduced.

Further, when a method of wiping the intermediate transfer belt by using a malt plane, felt, or the like as a cleaning means is adopted, it is expected that a problem occurs due to variation in pressure at which the cleaning member contacts the intermediate transfer belt. If the contact pressure is too low, cleaning cannot be performed, and if the contact pressure is too high, color misregistration at the time of superimposition of toner images of each color and an increase in required driving torque tend to occur because the intermediate transfer belt is not driven smoothly. In addition, the cleaning means has to be periodically replaced due to a decrease in wiping force due to wear of the cleaning means.

SUMMARY OF THE INVENTION Accordingly, a main object of the present invention is to provide a color image forming apparatus capable of preventing a malfunction due to a foreign substance or the like adhering to an intermediate transfer belt.

Another object of the present invention is to provide a color image forming apparatus in which cleaning means for removing foreign matter on an intermediate transfer belt can be easily provided.

Another object of the present invention is to provide a cleaning means for removing foreign matter on the intermediate transfer belt, which results in poor cleaning due to variations in surface pressure when the cleaning means comes into contact with the intermediate transfer belt, and a smooth drive of the intermediate transfer belt. An object of the present invention is to provide a color image forming apparatus capable of preventing a color shift at the time of superimposing toner images of a plurality of colors and an increase in required driving torque due to non-printing.

[0010]

The above object is achieved by a color image forming apparatus according to the present invention. In summary, the present invention is directed to a color image forming apparatus including an intermediate transfer body unit having a plurality of rollers and an intermediate transfer belt stretched over the rollers, and detects a head formed on the intermediate transfer belt. Means for cleaning the holes for use, and a container for accommodating foreign matter cleaned by the cleaning means, wherein the container is arranged on the upstream side of the cleaning means with respect to the moving direction of the intermediate transfer belt. This is a color image forming apparatus.

Preferably, the cleaning means is attached to a part of the container. It is preferable that the cleaning unit and the container are integrally attached to the intermediate transfer body unit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a color image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Overall Configuration of Color Image Forming Apparatus] FIG. 1 is an overall configuration diagram showing an embodiment of an electrophotographic color image forming apparatus (hereinafter, simply referred to as "image forming apparatus") according to the present invention.

First, an overall configuration of the image forming apparatus A will be schematically described with reference to FIG. The image forming apparatus A shown in FIG. 1 is a four-color laser beam printer.

The image forming apparatus A includes a drum type electrophotographic photosensitive member (hereinafter, referred to as a "photosensitive drum") as a first image carrier.
1). The photosensitive drum 1 is driven to rotate counterclockwise in FIG. 1 by a driving unit (not shown). A charging device 2 for uniformly charging the surface of the photosensitive drum 1 in order according to its rotation direction around the photosensitive drum 1, and irradiating a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1 A developing device 4 for attaching toner to the electrostatic latent image to develop it as a toner image, and a second device to which the toner image on the photosensitive drum 1 is primarily transferred.
And a cleaning device 6 for removing post-transfer toner remaining on the surface of the photosensitive drum 1 after the primary transfer.

Here, the photosensitive drum 1, the charging device 2, and the cleaning device 6 are integrated into a cartridge to form a process cartridge B, and the image forming apparatus main body 1
4 is detachable.

In addition, a recording medium (transfer material) S is fed toward the intermediate transfer body unit 5 and a feeding means 7 for feeding the transfer material S, and a toner image is transferred onto the transfer material S after the secondary transfer. Is provided.

Hereinafter, the elements constituting the image forming apparatus will be described in more detail.

The photosensitive drum 1 is provided with an organic photoconductor (OP) on an outer peripheral surface of, for example, an aluminum cylinder having a diameter of 47 mm.
C photoreceptor).

The photosensitive drum 1 is rotatably supported at both ends by support members, and is rotated in the direction of the arrow by a driving force transmitted from a driving motor (not shown) to one end. Driven.

The charging device 2 is described in, for example,
A so-called contact charging type as shown in JP-A-149669 can be used. The charging member is a conductive roller formed in the shape of a roller. The roller is brought into contact with the surface of the photosensitive drum 1, and a charging bias voltage is applied to the roller by a power supply (not shown). This is to uniformly charge the surface of the body drum 1.

The exposure means 3 has a polygon mirror 3a, and the polygon mirror 3a is irradiated with image light corresponding to an image signal by a laser diode (not shown). The polygon mirror 3a is rotated at a high speed by a scanner motor (not shown), and selectively exposes the surface of the charged photosensitive drum 1 to the reflected image light via the imaging lens 3b, the reflection mirror 3c, etc. It is configured to form an electrostatic latent image.

The developing device 4 accommodates a rotating member 4A rotatable around a shaft 4d and four developing devices mounted thereon, ie, toners of yellow, magenta, cyan, and black, respectively. Developing units 4Y, 4M, 4
C, 4Bk.

When an electrostatic latent image on the photosensitive drum 1 is developed, a predetermined developing device of a color to be attached to the electrostatic latent image is arranged at a developing position.

That is, a predetermined developing unit is stopped at a developing position opposed to the photosensitive drum 1 by the indexing rotation of the rotating body 4A, and the developing sleeve 4b of the developing unit is further provided with a minute gap (300 μm) with respect to the photosensitive drum 1. Then, the electrostatic latent image on the photosensitive drum 1 is developed.

This development is performed as follows. That is, the feeding mechanism 4e feeds the toner in the container of the developing device corresponding to the color to be developed.
The toner is applied to the outer periphery of the rotating developing sleeve 4b by the rotating applying roller 4a and the toner regulating blade 4c, and a charge is applied to the toner (friction charging).

By applying a developing bias between the developing sleeve 4b and the photosensitive drum 1 on which the electrostatic latent image is formed, toner is attached to the electrostatic latent image and developed as a toner image. is there. Further, each of the developing units 4Y, 4M, 4
The developing sleeve 4b of C, 4Bk is connected to a high-voltage power source for developing each color provided in the image forming apparatus main body 14 when each developing unit is arranged at the developing position, and develops each color. A voltage is selectively applied every time. Each of the developing devices 4Y, 4M, 4C, and 4Bk is configured to be individually detachable from the rotating body 4A.

An intermediate transfer unit 5 serving as a second image carrier transfers a plurality of toner images, which are sequentially primary-transferred and superimposed sequentially from the photosensitive drum 1, to a transfer material S in a batch. It is.

The intermediate transfer body unit 5 has an intermediate transfer belt 5a running in the direction of arrow R5. The intermediate transfer belt 5a of this embodiment is a belt having a circumference of about 440 mm, and is stretched over three rollers of a driving roller 5b, a secondary transfer facing roller 5c, and a driven roller 5d. Further, a pressing roller 5g is provided which is close to the driven roller 5d and presses the intermediate transfer belt 5a against the photosensitive drum 1 and which is retracted so that the intermediate transfer belt 5a is separated from the photosensitive drum 1.

The intermediate transfer belt 5a runs in the direction of arrow R5 by the rotation of the driving roller 5b. Further, at a predetermined position outside the intermediate transfer belt 5a, that is, downstream of the secondary transfer opposing roller 5c, a cleaning unit 5e that can be brought into contact with and separated from the surface of the intermediate transfer belt 5a is provided. Then, the transfer residual toner remaining after the secondary transfer is removed.

The cleaning unit 5e brings the charging roller 5f into contact with the intermediate transfer belt 5a to apply a charge to the toner which is opposite to that at the time of transfer. The toner to which the opposite charge has been applied is electrostatically attached to the photosensitive drum 1, and thereafter, is collected by a cleaning device 6 for the photosensitive drum 1, which will be described later. The method of cleaning the intermediate transfer belt 5a is not limited to the above-described electrostatic cleaning, but may be a mechanical method such as a blade or a fur brush, or a method using both of them.

After the toner developed on the photosensitive drum 1 by the developing device 4 is primarily transferred to the intermediate transfer belt 5a, the cleaning device 6 is a so-called untransferred toner remaining on the surface of the photosensitive drum 1 without being primarily transferred. Is to be removed.

In the cleaning device 6 shown in FIG. 1, the transfer residual toner is accumulated in the cleaning container 11a.

The feeding means 7 feeds the transfer material S to the image forming section, and contains a plurality of transfer materials S. Pickup roller (half moon roller) during image formation
The feed roller 7e, the feed roller 7f, and the retard roller 7g are driven and rotated in accordance with the image forming operation to separate the transfer material S in the paper feed cassette 7a by one sheet and to be transported along the guide plate 7c by the transport roller pair 7b. You. The leading end of the transfer material S abuts against the pair of registration rollers 7d and temporarily stops. After forming a loop, the rotation of the intermediate transfer belt 5a and the image writing position are synchronized, and the registration roller pair 7d re-feeds the sheet to the intermediate transfer body 5. Will be done.

The fixing device 8 fixes a plurality of toner images secondary-transferred onto the transfer material S. As shown in FIG. 1, a heating roller 8b which is driven and rotated is pressed against the transfer material S by pressing against the heat roller 8b. And a pressure roller 8a for applying heat and pressure to the pressure roller 8a. That is, the transfer material S that has passed through the secondary transfer roller 11 that collectively transfers the toner on the intermediate transfer belt 5a is transported on the transport belt unit 12, and when passing through the fixing device 8, the pressure roller 8a and the heating roller 8b And heat and pressure are applied by the heating roller 8b. Thus, the toner images of a plurality of colors are fixed on the surface of the transfer material S.

Next, an image forming operation in the image forming apparatus having the above configuration will be described.

The photosensitive drum 1 is rotated in the direction of the arrow (counterclockwise) in FIG. 1 in synchronism with the rotation of the intermediate transfer belt 5a, and the surface of the photosensitive drum 1 is uniformly charged by the charging device 2 and exposed. The yellow image is irradiated by the means 3 to form a yellow electrostatic latent image on the photosensitive drum 1. At the same time as the formation of the electrostatic latent image, the developing device 4
To place the yellow developing device 4Y at the developing position,
Applying a voltage of the same polarity and substantially the same potential as the charging polarity of the photoconductor drum 1 so that the yellow toner adheres to the electrostatic latent image on the photoconductor drum 1 to cause the yellow toner to adhere to the electrostatic latent image for development I do. Thereafter, a voltage having a polarity opposite to that of the toner is applied to the pressing roller (primary transfer roller) 5g of the intermediate transfer body unit 5 to primarily transfer the yellow toner image on the photosensitive drum 1 onto the intermediate transfer belt 5a.

When the primary transfer of the yellow toner image is completed as described above, the next developing unit rotates and moves to the developing position facing the photosensitive drum 1, and the magenta and yellow toner images are moved in the same manner as in the case of yellow. The formation, development, and primary transfer of an electrostatic latent image are sequentially performed for each color of cyan and black, and four color toner images are superimposed on the intermediate transfer belt 5a.

During this time, the secondary transfer roller 11 is not in contact with the intermediate transfer belt 5a. At this time, the charging roller 5f of the cleaning unit 5e is also in a non-contact state with the intermediate transfer belt 5a.

After the four color toners are completed on the intermediate transfer belt 5a, the secondary transfer roller 11 is moved to the intermediate transfer belt 5a.
a (in the state of FIG. 1), and the intermediate transfer belt 5a
The transfer material S waiting at a predetermined position near the registration roller pair 7d is sent out to the nip between the intermediate transfer belt 5a and the secondary transfer roller 11 in synchronization with the rotation of the transfer roller S.

Here, a voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 11, and the toner image on the intermediate transfer belt 5a is transferred onto the surface of the transfer material S conveyed at once. Transcribe.

The transfer material S thus secondary-transferred in this manner is
Reaches the fixing device 8 via the conveyor belt unit 12,
Here, after the toner image is fixed, the pair of paper discharge rollers 13
The sheet is conveyed along a sheet ejection guide 15 by a sheet ejection roller 16, and is discharged by a sheet ejection tray
0, and the image formation is completed.

Next, the cleaning means for the intermediate transfer belt and the container for the cleaning means, which are characteristic parts of the present invention, will be described in more detail with reference to FIGS.

As shown in FIG. 2, a hole 5h for detecting the image TOP, that is, the head position of the image, is formed in the intermediate transfer belt 5a near the end of the intermediate transfer belt 5a. A patch 5i is attached to the hole 5h to prevent current leakage when the hole 5h comes into contact with the photosensitive drum 1.

A photo interrupter 5j, which is a leading position detecting means, is attached to the intermediate transfer body unit 5 with the end of the intermediate transfer belt 5a interposed therebetween, and the hole 5h passes through a position corresponding to the photo interrupter 5j. sometimes,
The image TOP can be detected.

However, as described above, foreign matter such as undeveloped developer and waste toner leaking from the developing device is scattered by the air of the cooling fan (not shown) inside the current color image forming apparatus. If this foreign matter adheres to the patch 5i attached to the hole 5h, the optical path of the photointerrupter 5j is blocked, so that the TOP position cannot be detected.
The above-described primary transfer and secondary transfer cannot be performed.

Therefore, as shown in FIG. 3, a malt plane, a felt, a blade, a fur brush or the like is used as a cleaning means 5k for the hole 5h.
The patch 5i attached to the detection hole 5h is brought into contact with the patch 5i, and the foreign matter 5n is cleaned by running the intermediate transfer belt 5a.

Further, the collecting foreign matter container 5m is disposed upstream of the intermediate transfer belt 5a in the running direction with respect to the cleaning means 5k. Thus, by arranging the container 5m on the upstream side of the cleaning unit 5k, it is possible to capture the entire amount of foreign matter. If the container 5m is arranged at a position other than the upstream side of the cleaning means 5k, it is difficult to capture the entire amount of foreign matter, and the foreign matter that has not been captured is scattered again.
The detection of the OP position becomes impossible, and a problem occurs that the primary transfer and the secondary transfer cannot be performed. On the other hand, according to the present embodiment, the above problem can be prevented by disposing the container 5m on the upstream side in the intermediate transfer belt traveling direction with respect to the cleaning unit 5k.

Further, when a method of wiping the intermediate transfer belt 5a by using a malt plane, felt, a blade, a fur brush or the like as the cleaning means 5k, the pressure at which the cleaning means 5k contacts the intermediate transfer belt 5a varies. This is expected to cause a problem. For example, if the contact pressure is too low, cleaning cannot be performed, and if the contact pressure is too high, color misregistration at the time of superimposing toner images of each color and an increase in driving torque tend to occur because the intermediate transfer belt 5a is not driven smoothly. Become. Further, in order to reduce the wiping force due to wear of the cleaning means 5k, the cleaning means 5k is periodically checked.
Had to be replaced. Further, since foreign matter 5n accumulates in the container 5m, it is necessary to periodically empty the foreign matter 5n.

Therefore, as shown in FIG. 4, for example, the upper end portion of a trapped foreign matter container 5m formed in a square shape,
The cleaning means 5k is integrally attached as a cleaning unit 50 to the upper end 5m1 on the downstream side in the running direction of the intermediate transfer belt 5a indicated by reference numeral 5.

According to this structure, the wear state of the cleaning means 5k can be easily checked at the time of regular cleaning of the container 5m. Also, by mounting the cleaning unit 50 on the intermediate transfer body unit 5 instead of the image forming apparatus main body, the positioning accuracy with respect to the intermediate transfer belt 5a can be improved, so that the surface pressure of the cleaning unit 5k varies. This can prevent the occurrence of inconvenience caused by the above.

[0052]

As is apparent from the above description, according to the present invention, the means for cleaning the head detecting hole formed in the intermediate transfer belt, and the means for accommodating the foreign matter cleaned by the cleaning means. With respect to the moving direction of the intermediate transfer belt, by arranging the container on the upstream side of the cleaning unit, it is possible to prevent malfunction due to foreign matter or the like adhering to the intermediate transfer belt, By integrally attaching the cleaning means and the container to the intermediate transfer body unit, a cleaning means for removing foreign matters on the intermediate transfer belt can be easily maintained, and the cleaning means can be attached to the intermediate transfer belt. Improper cleaning due to variations in surface pressure at the time of contact, color misregistration at the time of superimposing toner images of multiple colors due to the intermediate transfer belt not being driven smoothly, and required driving torque. Can of preventing a large, it is possible to obtain a good image.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of an electrophotographic color image forming apparatus according to the present invention.

FIG. 2 is a perspective view showing an intermediate transfer unit in the color image forming apparatus of FIG. 1;

FIG. 3 is a side view illustrating an intermediate transfer body unit including a cleaning unit and a container.

FIG. 4 is a perspective view showing a cleaning unit in which a cleaning unit and a container are integrally formed.

[Explanation of symbols]

 Reference Signs List 5 intermediate transfer body unit 5a intermediate transfer belt 5b, 5c, 5d roller 5h hole 5i patch 5k cleaning means 5m container 50 cleaning unit

Claims (3)

[Claims] 1. A color image forming apparatus including an intermediate transfer body unit having a plurality of rollers and an intermediate transfer belt stretched over the rollers, wherein a head detection hole formed in the intermediate transfer belt is formed. Cleaning means, and a container for storing foreign matter cleaned by the cleaning means, wherein the container is arranged upstream of the cleaning means with respect to a moving direction of the intermediate transfer belt. Color image forming apparatus. 2. The color image forming apparatus according to claim 1, wherein said cleaning means is attached to a part of said container. 3. The color image forming apparatus according to claim 1, wherein said cleaning means and said container are integrally attached to said intermediate transfer unit.