JPH1124430A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an intermediate transfer body to be smoothly moved an to obtain an excellent-quality projected image even when an OHP sheet is used by alternately providing the intermediate transfer body with a first surface area having first smoothness and a second surface area having second smoothness. SOLUTION: Plural photoreceptors 9 are cylindrical, rotated synchronously with the movement of an intermediate transfer body 1 while being brought into contact with the transfer body 1 and are arranged at an equal interval in the moving direction of the transfer body 1. The transfer body 1 is provided with first and second surface areas 11 and 12. The length of the area 11 is made shorter than the interval between the photoreceptors 9 to each other. The area of the transfer body 1 other than the area 11 is the second surface area 12 where projections are arrayed in order to reduce friction with the photoreceptors 9. Thus, since the number of photoreceptors 9 brought into contact with the area 11 is <=1 at any point of time, the transfer body 1 is smoothly moved even when the flat area 11 where the projections are not arrayed, exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus having an intermediate transfer member for transferring a toner image transferred on a surface to a recording medium again.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for forming a full-color image has been known, and an image forming apparatus having an intermediate transfer member has been conventionally known. An image forming apparatus for forming a full-color image usually has four photoconductors, and the four photoconductors sequentially transfer images of four colors at the same position on the surface of the intermediate transfer body. The intermediate transfer member moves cyclically in the image forming apparatus while contacting the four photoconductors. If the friction with the photoconductors is large, the direction of the stress received from each of the four photoconductors is determined by the mounting direction of the photoconductors. The intermediate transfer member may not be able to move smoothly due to slight differences due to errors and the like. In this case, there is a possibility that the intermediate transfer member may be damaged, or the alignment of the images of the four colors may be misaligned, resulting in poor color reproducibility. In order to prevent this, generally, small regular projections are formed on the surface of the intermediate transfer member to reduce friction.

[0003]

However, when an image is formed on an OHP sheet by the above-described image forming apparatus, the structure of the toner for forming the image is formed by the projections formed on the surface of the intermediate transfer member. , OHP sheets tend to be scattered, so that the projected image of the OHP sheet may not reproduce the original color.

A method for solving this problem is disclosed in Japanese Unexamined Patent Publication No. 5-21.
No. 6322 and Japanese Patent Application Laid-Open No. 8-334916, this method requires the use of a special OHP sheet coated with a resin for improving image quality on the surface of a normal OHP sheet. Also, a new problem arises in that a background portion on which no image is formed becomes dark. In view of the above circumstances, the present invention provides an image in which the intermediate transfer body can move smoothly, and a high quality projected image can be obtained even when an OHP sheet whose surface is not coated with a resin for improving image quality is used. It is an object to provide a forming device.

[0005]

In order to achieve the above object, an image forming apparatus according to the present invention comprises a plurality of image carriers having a toner image formed on a surface thereof, and a plurality of image carriers which are in contact with each other. Each of the primary transfer positions and the intermediate transfer body that moves cyclically via a predetermined secondary transfer position, and the toner image formed on each image carrier is transferred to the surface of the intermediate transfer body at each primary transfer position. Primary transfer means for primary transfer, secondary transfer means for secondary transfer of a toner image transferred to the surface of the intermediate transfer member to a predetermined recording medium at a secondary transfer position, and simultaneously with secondary transfer or from secondary transfer A fixing means for fixing the toner image transferred onto the recording medium onto the recording medium, the intermediate transfer member alternately repeats in the intermediate transfer member moving direction. With multiple smoothness And having a first surface area at most in contact with one of the image bearing member simultaneously out of the body, and a second surface region having a second smoothness lower than the first smoothness.

In the present invention, the term "circularly moving intermediate transfer member" refers to a belt-shaped intermediate transfer member circulating in an image forming apparatus and a rotating drum-shaped intermediate transfer member. Both cases are included.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention. This image forming apparatus 10 includes:
An intermediate transfer body 1 having an endless belt-like structure is provided, and the intermediate transfer body 1 circulates in the image forming apparatus 10.
Further, the image forming apparatus 10 is provided with a transfer fixing device including a heat roll 2 and a pressure roll 3, which is a secondary transfer unit and a fixing unit according to the present invention.
The image forming apparatus 10 includes a supply tray 5 and a sheet feeder 6. The recording medium 4, which is an OHP sheet or paper, enters the supply tray 5, and the recording medium 4 is supplied by the sheet feeder 6. To the transfer fixing device. Further, the image forming apparatus 10 includes a strip finger 7 and an unloading tray 8.
Is peeled off, and the peeled recording medium 4 is carried out to the carry-out tray 8. Further, the image forming apparatus 10 is provided with a photoreceptor as an image carrier according to the present invention and a primary transfer unit according to the present invention, but is omitted in FIG. explain.

FIG. 2 is a schematic diagram showing the structure of the surface of the intermediate transfer member 1 shown in FIG. The intermediate transfer member 1 has an endless belt-like structure as described above. Two lines A shown in FIG. 2 represent the same line on the intermediate transfer body 1, and a portion sandwiched between the two lines A represents the entirety of one intermediate transfer body. This intermediate transfer body 1 has a first surface area 1
The first surface region 12 has first and second surface regions 12, and the second surface region 12 has regularly arranged projections 121 that are coarser than the first surface region 11. The two circles of the two-dot chain line on the right side of FIG.
FIG. 3 is an enlarged view of a second surface region 12. The first surface region 11 is a flat region where no protrusion 121 is formed. Also, the protrusions 121 arranged in the second surface area
Are arranged for the purpose of reducing the friction with the photoreceptor, like the intermediate transfer member of the conventional image forming apparatus.

The intermediate transfer body 1 does not necessarily need to have regular projections, but may have a second surface area 12.
However, any region may be used as long as the surface roughness is larger than that of the first surface region 11. The intermediate transfer body 1 is an intermediate transfer body 1
May have a plurality of first surface regions 11 sandwiched by the second surface regions 12 during one cycle. FIG.
FIG. 2 is a schematic diagram illustrating a relationship between a photoconductor, a primary transfer unit, and an intermediate transfer body that are not illustrated in FIG. 1.

The photosensitive member 9 is cylindrical, and rotates in synchronization with the movement of the intermediate transfer member 1 while being in contact with the intermediate transfer member 1. A plurality of photoconductors 9 are arranged at regular intervals in the moving direction of the intermediate transfer body 1, and three photoconductors 9 are illustrated here. Further, the primary transfer means 13 is arranged at a position facing the photoconductor 9 with the intermediate transfer body 1 interposed therebetween. The length of the first surface region 11 in the moving direction of the intermediate transfer member 1 is shorter than the interval between the photoconductors 9 and, as shown in FIG.
The area of the intermediate transfer body 1 other than the first surface area 11 is a second surface area 12 on which projections are arranged in order to reduce friction with the photoconductor 9. As a result, the number of the photoconductors 9 that come into contact with the first surface region 11 is always one or less at any time, so that the flat regions are not provided with projections for reducing friction with the photoconductors 9. Even if the first surface region 11 exists, the intermediate transfer body 1 moves smoothly.

As described above, the intermediate transfer member 1 may have a plurality of first surface regions 11 sandwiched between the second surface regions 12 while making a round of the intermediate transfer member 1. In this case, by setting the interval between the plurality of first surface regions 11 to an appropriate interval, the number of the photoconductors 9 in contact with the first surface region 11 is always one or less at any time.
Returning to FIG. 1, the description will be continued. Primary transfer means 1 shown in FIG.
3, a toner image is formed on the surface of the intermediate transfer member 1. The image forming apparatus 10 includes a synchronization unit (not shown), and the movement of the intermediate transfer body 1 and the transfer by the primary transfer unit 13 are synchronized by the synchronization unit. Thereby, when the recording medium 4 is an OHP sheet, the OH
Since it is necessary to prevent the transmitted light of the P sheet from being scattered, the toner image is primarily transferred to the first surface area 11 which is a flat surface area shown in FIG. Also, the recording medium 4
Is paper, it is not necessary to consider the scattering of light, so that it is formed on any one of the first surface area 11 and the second surface area 12, and the image quality is reduced in the middle of the surface. In order to avoid a change, it is formed so as not to protrude the boundary between the surface regions.

When the intermediate transfer body 1 has only one first surface area 11, the place where the toner image for transfer and fixing to the OHP sheet is formed is limited to one place. The production speed of the image to be fixed is low. Therefore, it is desirable to increase the production speed by using the intermediate transfer body 1 having a plurality of first surface regions 11 sandwiched by the second surface regions 12 while making a round of the intermediate transfer body 1. Further, the OHP sheet is used in an arrangement in which the short side of the OHP sheet is along the moving direction of the intermediate transfer body 1,
The first surface area 1 is large enough to fit the entire OHP sheet.
1, the area of the first surface region 11 is reduced to O while maintaining the production speed of the image fixed on the OHP sheet.
The size of the image forming apparatus 10 can be reduced by reducing the size of the image forming apparatus 10 by shortening the interval between the photoconductors 9, as compared with the case where the HP sheet is used so that the long side of the OHP sheet is along the moving direction of the intermediate transfer body 1. Can also be reduced.

The recording medium 4 is conveyed from the supply tray 5 to the transfer / fixing device via the sheet feeder 6 in synchronization with the movement of the toner image to the transfer / fixing device along with the movement of the intermediate transfer member 1. In this transfer fixing device, the recording medium 4 is associated with the intermediate transfer body 1, and the heat and pressure of the heat roll 2 and the pressure roll 3 cause the toner image formed on the intermediate transfer body 1 by the primary transfer means 13 to be recorded on the recording medium 4. The recording medium 4 is stuck on the intermediate transfer body 1 with the toner image interposed therebetween. With the movement of the intermediate transfer member 1, the recording medium 4 is conveyed while being stuck to the intermediate transfer member 1, and when approaching the unloading tray 8, the recording medium 4 is peeled off by the strip fingers 7 and is unloaded onto the unloading tray 8. It is carried out.

The process in which the toner forming the toner images formed on the first and second surface areas is transferred and fixed to the recording medium will be described below. FIG. 4 is a schematic diagram illustrating a process in which the toner constituting the toner image formed on the second surface area is transferred and fixed. Since the protrusions 121 are arranged on the surface of the intermediate transfer body 1, as shown in FIG. 4A, when the toner 20 forming the toner image enters between the protrusions 121, the transfer and fixing device Even when the intermediate transfer body 1 and the recording medium 4 are pressed against each other by receiving heat and pressure, the toner 121 is not sufficiently spread by the protrusions 121 as shown in FIG. Therefore, as shown in FIG. 4C, the toner 20 is fixed on the recording medium 4 in a state having a three-dimensional structure. Even in the case of an image formed with such a toner 20, when viewed with reflected light, color reproducibility is sufficient. However, when a projected image is formed by using transmitted light, light is scattered by the three-dimensional structure of the toner 20 and color reproducibility is poor. In particular, color reproducibility is poor in an image having a clear image structure, such as when a halftone on the highlight side is formed by halftone dots or lines.

FIG. 5 is a schematic diagram showing a process in which the toner constituting the toner image formed on the first surface region 11 is transferred and fixed. As shown in FIG. 5A, the first surface region 11 does not have any protrusions arranged in the second surface region 12 and has a flat surface structure. Therefore, when heat and pressure are applied to the intermediate transfer body 1 and the recording medium 4 by the transfer fixing device, the toner 20 is sufficiently supplied between the recording medium 4 and the intermediate transfer body 1 as shown in FIG. Will be spread. As a result, the toner 20 is transferred and fixed onto the recording medium 4 without a three-dimensional structure as shown in FIG. The image formed by the sufficiently spread toner 20 as described above transmits light without being scattered. Therefore, even when a projected image is formed using transmitted light, color reproducibility is good.

[0016]

EXAMPLE An example in which the above embodiment is actually implemented will be described. First, an intermediate transfer member was prepared by the method described below. FIG. 6 is a schematic process diagram showing a production process when an intermediate transfer member is produced. Silicon resin was applied to the entire base layer 31 of the intermediate transfer body 30. The surface of the projection forming die 33 for an intermediate transfer body having a high halftone dot area ratio (for example, a halftone dot area ratio of 80%) has a structure in which holes 331 are regularly arranged (enlarged view (FIG. 3C )), The intermediate transfer member projection forming die 33 is applied to the first surface area as shown in FIG. 6A before the silicon resin layer 32 applied to the entire base layer 31 is dried. The image was placed on the intermediate transfer member 30 such that the image was in contact with the silicone resin layer 32 except for the region indicated by. After the silicon resin was dried, as shown in FIG. 6B, the second transfer surface 34 having regular protrusions was formed by peeling off the protrusions 33 for forming an intermediate transfer body. The first surface region 35 having a flat surface structure is dried by drying the region where the projection forming die 33 for the intermediate transfer member is not placed while the surface structure of the applied silicon resin remains flat. Formed.

An image was formed on an OHP sheet by an image forming apparatus using the intermediate transfer member 30, and the transmittance of the OHP sheet was measured.

[0018]

[Table 1]

As shown in Table 1, when the toner image formed on the second surface area 34 whose surface was processed by the projection forming die 33 for the intermediate transfer member was transferred and fixed as in the prior art,
The transmittance of the HP sheet was as low as 60% or less. However, when the image formed on the first surface area 35 which was dried while the silicon resin surface was kept flat was transferred and fixed.
The transmittance of the HP sheet becomes a high value of 82%, and the OH
The value was sufficient to reproduce the color in the projected image of the P sheet.

[0020]

As described above, according to the image forming apparatus of the present invention, the intermediate transfer member can move smoothly, and good quality can be obtained even if an OHP sheet whose surface is not coated with a resin is used. It is possible to obtain a proper projected image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic diagram illustrating a surface structure of an intermediate transfer member illustrated in FIG.

FIG. 3 is a schematic diagram illustrating a relationship between a photosensitive member and an intermediate transfer member.

FIG. 4 is a schematic diagram illustrating a process of transferring and fixing a toner constituting a toner image formed on a second surface region.

FIG. 5 is a schematic diagram illustrating a process in which a toner constituting a toner image formed on a first surface region is transferred and fixed.

FIG. 6 is a schematic view illustrating a method for producing an intermediate transfer member.

[Explanation of symbols]

 Reference Signs List 1, 30 Intermediate transfer member 2 Heat roll 3 Pressure roll 4 Recording medium 5 Supply tray 6 Sheet feeder 7 Strip finger 8 Unloading tray 9 Photoreceptor 11, 35 First surface area 12, 34 Second surface area 13 Primary transfer means 121 Projection 33 Projection making type for intermediate transfer body

Claims (4)

[Claims] A plurality of image carriers having a toner image formed on a surface thereof, a primary transfer position in contact with each of the plurality of image carriers, and a predetermined secondary transfer position. An intermediate transfer member that moves cyclically, a primary transfer unit that primarily transfers the toner image formed on each image carrier to the intermediate transfer member at each of the primary transfer positions, and an image that is transferred to the intermediate transfer member. Secondary transfer means for secondary transfer of the toner image to a predetermined recording medium at the secondary transfer position, and simultaneously with the secondary transfer or later than the secondary transfer,
A fixing unit for fixing the toner image transferred onto the recording medium onto the recording medium, wherein the intermediate transfer body is alternately repeated in the intermediate transfer body moving direction. A first surface region having at least one image carrier at the same time and having a second smoothness lower than the first smoothness. An image forming apparatus having a surface region. 2. The image forming apparatus according to claim 1, wherein the second surface region has regularly arranged projections that are coarser than the first surface region. 3. The image forming apparatus according to claim 1, wherein the second surface area is an area having a larger surface roughness than the first surface area. 4. The intermediate transfer member according to claim 1, wherein the intermediate transfer member has a plurality of the first surface regions sandwiched by the second surface regions while making a round of the intermediate transfer member. Image forming device.