JP2000105493A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of improving its maintainability by enabling maintenance from one surface of the image forming device. SOLUTION: In this image forming device provided with a photoreceptor on which electrostatic latent images of plural colors are formed, a developing means to form a colored image by developing the electrostatic latent images, an intermediate transfer body by which the colored image formed by the developing means is successively laid over, a transfer means for transferring the colored image formed on the intermediate transfer body to a recording medium and a fixing means for fixing the colored image transferred to the recording medium by the transferring means, the photoreceptor and the intermediate transfer body are constituted by an endless belt laid in a nearly perpendicular direction by holding rollers which are at least positioned on upper and lower sides by incorporating one arranged on the lower side, and are attachable and detachable in a perpendicular line direction in a photoreceptive unit provided with the photoreceptor 2 and an intermediate transfer unit provided with the intermediate transfer body 7c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus for superimposing and transferring a plurality of color images on an intermediate transfer belt to obtain a color image.

[0002]

2. Description of the Related Art An image forming apparatus forms an electrostatic latent image for each color-separated document information or document light, and develops the electrostatic latent image with toner of a color complementary to the color separation color. There is a device that forms a color image by superimposing a visible image that has been subjected to visible image processing with an agent for each color separation image. In a color image forming apparatus, as a configuration for performing superimposed transfer, there is a configuration using a transfer belt that can be brought into contact with a photoconductor (for example, Japanese Patent Application Laid-Open
-289666). The publication discloses a photoreceptor belt wrapped around a pair of pulleys arranged in a vertical line,
A configuration including an intermediate transfer belt in which an extended surface including a transfer position is set to be inclined with respect to the photosensitive belt is shown. In the above configuration, the visible image formed on the photoreceptor belt is primary-transferred and superimposed on the intermediate transfer belt for each color separation, and the superimposed visible image is collectively secondary-transferred to recording paper or the like. ing.

[0003]

When the intermediate transfer belt is used as an image superimposing member, the space occupied by the transfer mechanism can be reduced as compared with a drum or the like. In the configuration of the above publication, the extended surface including the transfer position where the intermediate transfer belt is in contact with the photoreceptor belt is inclined, and one and the other of the inclined surfaces, and further, are positioned below the inclined surfaces. It is hung on a pulley. Therefore,
The shape formed by all the extended surfaces of the intermediate transfer belt is an upward triangle. In the case of such a shape formed by the extended surface, maintainability is deteriorated. Since the photoreceptor belt is hung around pulleys positioned in the vertical direction, the extending surface is in the vertical direction, and can be pulled out upward. However, if the photoreceptor belt is still mounted, even if an attempt is made to pull up the intermediate transfer belt, the intermediate transfer belt will interfere with the photoreceptor belt due to the shape formed by the extended surface, and cannot be pulled up. In recent years, in addition to reducing the space occupied by the transfer mechanism including the photoconductor, improvement in maintainability has been desired. As a countermeasure for this, it is required that if an operator stands on one side of the image forming apparatus, for example, the front of the image forming apparatus, maintenance work such as replacement of each mechanical component can be performed without changing its position. You. However, in the above configuration, depending on the maintenance target, the image forming apparatus cannot be pulled out from one surface.

On the other hand, in a mechanism using a belt, it is necessary to apply a tension to the belt to prevent the transfer position from shifting due to slippage. However, depending on the arrangement of the tension roller for applying the tension, the following is required. There is a problem. In the configuration of the above publication, if a tension roller is disposed near the rear of the primary transfer position in the moving direction of the photosensitive belt, the photosensitive belt approaches the intermediate transfer belt. This makes the image primarily transferred to the intermediate transfer belt susceptible to the electrostatic force of the photoreceptor belt,
The temporarily transferred image on the intermediate transfer belt is easily disturbed. Such a phenomenon also occurs when a tension roller is disposed near the rear of the primary transfer position in the moving direction of the intermediate transfer belt. When a tension roller is disposed near the front of the secondary transfer position in the moving direction of the intermediate transfer belt,
Due to the arrangement of the recording paper entry guide member near that position, if the distance between the intermediate transfer belt and the guide member changes, the electrostatic attraction force at the secondary transfer position is located ahead of the secondary transfer position. This makes it easier to operate, and the image in the unfixed state is disturbed. In particular, the toner in the image is easily scattered by the discharge at the time of low temperature and low humidity, and the disturbance of the image becomes remarkable. Furthermore, the angle of entry of the recording paper guided by the entry guide member and the distance between the entry guide member and the intermediate transfer belt are extremely important factors for preventing image scattering and image disturbance due to flutter of thick paper. However, if the position and angle of the intermediate transfer belt are changed by the tension roller, it becomes difficult to determine the structure of the approach guide member. In particular, since the amount of displacement of the belt when a tension roller is used varies depending on the belt length, variations in the precision of parts used in the mechanism, and the like, subtle adjustment control corresponding to this is hardly possible. For this reason, the above-described image disturbance becomes remarkable.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional image forming apparatus using a belt, an object of the present invention is to provide a structure capable of improving maintenance by enabling maintenance work from one side of the image forming apparatus. An object of the present invention is to provide an image forming apparatus having the same.

Another object of the present invention is to provide a structure capable of preventing an image from being disturbed even when there is variation in the amount of overhang of a belt when a tension roller is used as a tension applying member of the belt. An object of the present invention is to provide an image forming apparatus having the same.

Still another object of the present invention is to provide an image forming apparatus in which, when a tension roller for applying tension to a belt adjacent to a recording paper entrance guide member is provided, the distance between the entrance guide member and the belt does not change. An object of the present invention is to provide an image forming apparatus having a configuration that can prevent disturbance.

[0008]

According to the first aspect of the present invention,
A photoreceptor on which electrostatic latent images of a plurality of colors are formed; developing means for developing the electrostatic latent images into colored images; and intermediate transfer capable of sequentially overlapping the colored images formed by the developing means. Body, a transfer unit that transfers the colored image formed on the intermediate transfer body to a recording medium, and an image forming apparatus that includes a fixing unit that fixes the colored image transferred to the recording medium by the transfer unit. The photoreceptor unit having the photoreceptor and the intermediate transfer unit having the intermediate transfer member were suspended in a substantially vertical line by at least upper and lower holding rollers including one disposed below. The photosensitive member and the intermediate transfer member are constituted by an endless belt,
The photosensitive member and the intermediate transfer member are characterized in that they are detachable along the vertical line direction.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, one of the holding rollers for the photosensitive member has a diameter of 15 mm or more and a wrap angle of 20 degrees or more. It is characterized by comprising a tension roller which is disposed between the adjacent holding rollers at the shortest interval and adjusts the tension of the photoconductor.

According to a third aspect of the present invention, in the image forming apparatus of the first aspect, one of the holding rollers of the intermediate transfer member has a diameter of 15 mm or more and a winding angle of 20 degrees or more, And a tension roller for adjusting the tension of the intermediate transfer member, which is disposed between the holding rollers adjacent to each other at the shortest interval.

[0011]

FIG. 1 is a schematic diagram for explaining a main configuration of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, the image forming apparatus is a color printer, and the color printer 1 has a belt-shaped photoconductor (hereinafter, referred to as a photoconductor) inside a housing.
A photosensitive belt 2). Photoreceptor belt 2
Represents a main part of a photoreceptor unit detachably provided in the housing, and a pulley 3 corresponding to a holding roller vertically arranged including one positioned below,
3 '. The extension surface of the photoreceptor belt 2 wrapped around the pulleys 3 and 3 'is set in a substantially vertical direction, and the extension surface faces a developing device described later. Among the holding rollers 3 and 3 ', the holding roller indicated by reference numeral 3 is a drive roller, and the photosensitive belt 2 is moved in the direction of the arrow in the figure by this roller.

Around the photoreceptor belt 2, there are provided a charging device 4, a writing device 5, a developing device 6, a transfer unit 7, and a cleaning means 8 for executing an electrophotographic process along the moving direction. The photosensitive belt 2 is uniformly charged by the charging device 4 along the moving direction, and the writing device 5 forms an electrostatic latent image corresponding to image information.

The electrostatic latent image is processed into a visible image by a developing device 6, and the visible image is transferred by a transfer unit 7. After the transfer, the photosensitive belt 2 is removed of the residual developer and residual charges by the cleaning unit 8 and moves toward the charging device 4 to prepare for the formation of the electrostatic latent image again. In this embodiment,
Since the printer is a color printer, an electrostatic latent image formed on the photoreceptor belt 2 is formed for each color separation, and the visible image processing is also performed on the electrostatic latent image for each color separation. For this reason,
The developing device 6 includes a plurality of developing tanks 6A and a developing roller 6B capable of supplying toner of a color complementary to the color-separated electrostatic latent image.

The transfer unit 7 is provided in a transfer unit that is detachably provided in the housing and has a transfer belt 7C, which will be described later, as a main part. The transfer unit 7 is vertically arranged including one located below. Pulley 7 corresponding to the holding roller
A belt 7C (hereinafter referred to as an "intermediate transfer belt"), which is wound around A and 7B, and one of the pulleys 7A is moved in a direction indicated by an arrow by a corresponding drive pulley. The extension surface of the intermediate transfer belt 7C wound around the pulleys 7A and 7B is set in a substantially vertical direction, and the extension surface faces the photoreceptor belt 2. The transfer unit 7 includes the photosensitive belt 2
A primary transfer unit is provided at a position facing the recording paper, and a secondary transfer unit is provided in the vicinity of a recording paper entry guide member 14 provided in a paper supply unit described later. In the primary transfer section, a pair of transfer rollers 9 is provided inside the intermediate transfer belt 7C, and the transfer roller 9 applies a transfer bias to electrostatically transfer the visible image on the photoreceptor belt 2 to electrostatic. Transcribe. In this embodiment, a pressing roller 10 is provided inside the photoreceptor belt 2 facing the transfer roller 9 so as to face the center of the transfer roller 9 in the parallel direction.

The secondary transfer section is provided with a pressing roller 11 disposed inside the intermediate transfer belt 7C.
The transfer roller 12 opposes the pressure roller 11 with the intermediate transfer belt 7C interposed therebetween. In the moving direction of the intermediate transfer belt 7C, a cleaning unit 13 that removes the developer and the charge remaining after the transfer is disposed behind the secondary transfer unit.

A recording paper entry guide member 14 is provided in front of the secondary transfer portion in the moving direction of the intermediate transfer belt 7C. The entry guide member 14 is a component of the sheet feeding device 15.
The recording paper accommodated in A is fed out by a feed-out roller 15B and fed toward the entry guide member 14, and a plurality of guide rollers 15C are arranged in the middle of the feeding path. In the vicinity of the secondary transfer unit, a fixing unit 16 is provided, which is swingably supported so as to be able to be opened from the housing of the color printer. In the fixing unit 16, a fixing device 16A and a fixing device are provided. A paper discharge roller 16B for discharging the recording paper is disposed.

The photosensitive belt 2 and the intermediate transfer member 7
C is wound around three holding rollers including the pressing rollers 10 and 11, has a diameter of 15 mm or more (minimum diameter: 25.4 mm), and has a belt winding angle of 20 mm.
The degree is set to be equal to or higher than the degree (31 degrees for the pressing roller 10 and 43 degrees for the pressing roller 11).

Since only one pulley is disposed below the photosensitive belt 2 and the intermediate transfer belt 7C wound around each holding roller, the photosensitive belt 2 and the intermediate transfer belt 7C are extended in a downward triangular shape by the three holding rollers. Will be.

Since the present embodiment has the above configuration,
At the time of maintenance such as replacement of the photosensitive belt 2 or the intermediate transfer belt 7C, as shown in FIG.
To the housing of the color printer. When the fixing unit 16 is opened, the photoconductor unit including the photoconductor belt 2 and the intermediate transfer belt 7 </ b> C and the intermediate transfer unit are opened above the arrangement positions.
Alternatively, the intermediate transfer belt 7C can be pulled up and can be detached. In other words, the photoreceptor belt 2 and the intermediate transfer belt 7C both have a substantially vertical extending surface by pulleys 3, 3 'and 7A, 7B, which are holding rollers arranged vertically, and further have a downward triangular shape. Since the extending surface is formed, there is no interference between adjacent belts. Therefore, in the case of the color printer,
Each belt can be pulled out from the upper wall corresponding to the same surface, so the space occupied by the belt can be reduced, and the belt can be removed from different directions during maintenance, facilitating maintenance work. It becomes possible to do.

Next, another embodiment of the present invention will be described.

In another embodiment of the present invention, each of the above-mentioned holding rollers is disposed between the adjacent holding rollers at the shortest interval between the holding rollers around which the photosensitive belt 2 and the intermediate transfer belt 7C are wound. It is characterized in that a holding roller constituted by a tension roller is arranged separately from the above. In FIG. 3 for explaining another embodiment of the present invention, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. In FIG.
The photoreceptor belt 2 in the photoreceptor unit includes a pressing roller 10 and a tension roller 17 in addition to the pulleys 3 and 3 'as holding rollers. The pulleys 3, 3 'and the pressing roller 10 located on the photoconductor unit side
Both have a diameter of 15 mm or more and a belt wrap angle of 20
Degrees, and in this embodiment, the pulleys 3 and 3 '
Has a diameter of 31.5 mm, and the pressing roller 10 has a diameter of 21.5 mm.
5.4 mm, and the winding angle of the belt around the pressing roller 10 is set to 31 degrees.

Pulley 7 located on the intermediate transfer unit side
A, 7B and the pressing roller 11 each have a diameter of 15 mm.
As described above, the winding angle of the belt is set to 20 degrees or more. In this embodiment, the pulleys 7A and 7B
mm, the diameter of the pressing roller 11 is 25.4 mm, and the winding angle of the belt around the pressing roller 11 is set to 45 degrees. With the setting of the diameter and the winding angle, the photoreceptor belt 2 and the intermediate transfer belt 7C maintain a downward triangular shape in which the extending surfaces between the pulleys 3 and 3 'and 7A and 7B are substantially vertical. .

The distance between the pulley 3 ′ and the pressing roller 10, where the distance between the holding rollers is shortest on the photosensitive unit side, is
In addition to these holding rollers, a tension roller 17 is disposed as another holding roller. The tension roller 17 is located at a position upstream of the primary transfer portion (the area indicated by the symbol A in FIG. 3) in which the photoreceptor belt 2 and the intermediate transfer belt 7C are in contact with each other to apply tension. Therefore, the intermediate transfer belt 7C after the primary transfer and the photosensitive belt 2 do not approach each other as shown by the two-dot chain line in FIG. Thereby, it is possible to prevent the transfer image from being disturbed due to the contact from the photosensitive belt 2 to the unfixed transfer image, which occurs when the photosensitive belt 2 approaches the intermediate transfer belt 7C after the primary transfer.

On the other hand, on the intermediate transfer unit side, a tension roller 18 is disposed between the pulley 7B, which has the shortest interval between the holding rollers, and the pressing roller 11, as another holding roller in addition to the holding rollers. I have. The tension roller 18 is located on the downstream side in the belt moving direction from a secondary transfer portion (the area indicated by the symbol B in FIG. 3) where the intermediate transfer belt 7 </ b> C and the entry guide member 14 are close to each other, and applies tension. 3, it is possible to prevent a situation in which the intermediate transfer belt 7 </ b> C inadvertently overhangs the entry guide member 14, as shown by a two-dot chain line in FIG. 3. Thus, when the distance between the intermediate transfer belt 7C and the guide member 14 changes, the image in the unfixed state is disturbed by the electrostatic attraction force from the secondary transfer portion ahead of the secondary transfer portion. This can be prevented from occurring. In addition, since the position of the intermediate transfer belt 7C facing the entrance guide member 14 does not change, the entrance guide member 14 is optimized so that recording paper, including thick paper, does not contact the intermediate transfer belt 7C before the secondary transfer. It can be formed under various conditions.

[0025]

According to the first aspect of the present invention, a photoreceptor is formed by extending a stepless belt, which is suspended in a substantially vertical direction by holding rollers located at least vertically including at least one below, in a downward triangle shape. And an intermediate transfer member,
It is possible to remove in the same direction without extending surfaces that interfere with each other in the vertical direction. This eliminates the need to perform maintenance work in different directions, thereby improving maintainability.

According to the second and third aspects of the present invention, since the tension roller is disposed between the holding roller adjacent to the photosensitive belt and the intermediate transfer belt at the shortest interval, the photosensitive belt or the intermediate transfer belt is transferred. There is no inadvertent overhang. As a result, it is possible to prevent the electrostatic force from easily acting upon overhang and prevent the unfixed image from being carelessly disturbed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a main configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the operation of the image forming apparatus shown in FIG.

FIG. 3 is a schematic diagram for explaining a main configuration of an image forming apparatus according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoreceptor belt provided in photoreceptor unit 3, 3 'Pulley corresponding to holding roller 7 Transfer unit 7A, 7B Pulley corresponding to holding roller 7C Intermediate transfer provided in intermediate transfer unit Belt 9 Transfer roller of primary transfer section 10, 11 Press roller 12 Transfer roller of secondary transfer section 17, 18 Tension roller

Claims (3)

[Claims] A photosensitive member on which a plurality of electrostatic latent images are formed;
Developing means for developing the electrostatic latent image into a colored image, an intermediate transfer member capable of sequentially overlapping the colored images formed by the developing means, and a colored image formed on the intermediate transfer member. An image forming apparatus comprising: a transfer unit for transferring to a recording medium; and a fixing unit for fixing the colored image transferred to the recording medium by the transfer unit. The image forming apparatus includes: a photoconductor unit including the photoconductor and the intermediate transfer member. The provided intermediate transfer unit, the photosensitive member and the intermediate transfer member are configured by an endless belt suspended in a substantially vertical line by a holding roller positioned at least vertically including one disposed below, An image forming apparatus, wherein the photosensitive member and the intermediate transfer member are detachable along the vertical line direction. 2. The image forming apparatus according to claim 1, wherein one of the holding rollers of the photoreceptor has a diameter of 15 mm or more and a winding angle of 20 degrees or more, and is arranged at the shortest interval between the holding rollers. An image forming apparatus comprising: a tension roller disposed between adjacent holding rollers to adjust the tension of a photoconductor. 3. The image forming apparatus according to claim 1, wherein one of the holding rollers of the intermediate transfer body has a diameter of 15 mm.
The winding angle is set to 20 degrees or more, and the tension roller is arranged between the holding rollers adjacent to each other at the shortest interval between the holding rollers to adjust the tension of the intermediate transfer member. Image forming apparatus.