JPH11143252A - Intermediate transfer body and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer body capable of preventing trouble such as an image defect from occurring because a fault such as the damage and the peeling of a surface layer is easily found out by visual observation, and an image forming device provided with the intermediate transfer body and improved in the detection accuracy of the density difference of a toner image whose density is low to middle so that the accuracy of density control is improved. SOLUTION: This intermediate transfer body 2 is used in a color image forming device where the images of plural colors formed on a 1st image carrier are primarily transferred successively from the first color to the intermediate transfer body 2 being a 2nd image carrier, and then the images formed on the transfer body 2 are secondarily transferred to transfer material altogether so as to obtain a color image. In such a case, by making material constituting the transfer body 2 incorporate paint or coating the surface of the transfer body 2 with the paint, the transfer body 2 is colored. This image forming device is provided with the intermediate transfer body.

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 and an intermediate transfer member used for the same. In particular, the transferable image (toner image) formed on the photoconductor, which is the first image carrier, is once primarily transferred onto the intermediate transfer body, which is the second image carrier, and the third image is transferred to the intermediate transfer body by the third transfer. An image forming apparatus such as a copying machine, a printer, and a facsimile that obtains an image-formed product (copy / print) by pressing a transfer material as an image carrier with a contact transfer member and performing a secondary transfer to the transfer material, and an intermediate transfer used for the same About the body.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an intermediate transfer member has a plurality of intermediate transfer members by forming a transferable image on a first image carrier and repeating a primary transfer process of the image onto the intermediate transfer member. A device for forming a color image (or a multi-color image) composed of a color developer and then secondary-transferring the image collectively to a transfer material to output an image-formed product in which color image information is synthesized and reproduced; Or is effective as an image forming apparatus having a color image forming function,
It is possible to obtain an image free from overlapping deviation (color deviation) of each component color image.

In the above-described image forming apparatus, high voltages such as a primary transfer bias, a secondary transfer bias, and a cleaning bias are applied to an intermediate transfer member during image formation. The intermediate transfer body has a structure in which a high-resistance surface layer is provided on a low-resistance elastic layer.Even if there are minute scratches or peeling on the surface layer, high pressure leaks and image formation is not performed normally, causing image defects. May cause. Therefore, it is important to manufacture the intermediate transfer member so that the surface layer is not scratched or peeled off.

Some full-color printers requiring high-precision density stability are provided with density detection means to detect the density of a toner image on a photoreceptor in the main body of the apparatus and to automatically control the density. .

However, with the recent miniaturization of the apparatus, the photoreceptor has also been reduced in size and diameter, and a density detector has been arranged around the photoreceptor in addition to a charger, a developing device and a cleaner. Is very difficult.

To solve the above problem, for example, there is a method of arranging a density detecting means on the intermediate transfer body and detecting the density of the toner image primarily transferred on the intermediate transfer body.

[0007]

However, in the above-described structure, the appearance of the intermediate transfer member may be black or very dark depending on the material used.

In the course of manufacturing an intermediate transfer member, it is difficult for even a skilled worker to confirm defects such as minute scratches or peeling on the surface layer of the high-concentration intermediate transfer member by visual inspection. Will be shipped without noticing the defective product. Furthermore, after shipping, if it is damaged during transportation or installation, it is almost impossible for unskilled service personnel or users to find the defect, and the image is installed without being aware of the defect. It may cause a defect.

Further, the image forming apparatus which performs density detection on the intermediate transfer member has the following problem. Images in the low-density region are particularly sensitive to the human eye, and require precision in density control. However, there is also a problem that the control accuracy of the low- to moderate-density toner image primarily transferred on the high-density intermediate transfer member is reduced if the detection accuracy of the density difference is reduced.

Accordingly, an object of the present invention is to provide an intermediate transfer member which can easily detect defects such as scratches and peeling of the surface layer by visual observation, thereby preventing troubles such as image defects, and the like. An object of the present invention is to provide an image forming apparatus in which the accuracy of density control is improved because the detection accuracy of the density difference between toner images of density to medium density is improved.

[0011]

SUMMARY OF THE INVENTION The present invention provides a first aspect.
The image formed on the image carrier is primarily transferred to the intermediate transfer member as the second image carrier in a plurality of colors sequentially from the first color, and then the image formed on the intermediate transfer member is transferred to a transfer material. In the intermediate transfer body used in a color image forming apparatus that obtains a color image by batch secondary transfer, a paint is contained in a material constituting the intermediate transfer body, or a surface is coated with a paint on the surface of the intermediate transfer body. And an intermediate transfer member characterized by being colored.

Further, the present invention is the above-mentioned intermediate transfer member, characterized in that the color after coloring is rendered achromatic.

Further, the present invention is the above-mentioned intermediate transfer member, characterized in that a colorless coating is applied to the surface after coloring.

In particular, according to the present invention, the reflection density of the surface is 0.2
The intermediate transfer member is characterized by being in the range of 0.8 to 0.8.

With the above-described structure, defects such as scratches and peeling of the surface layer can be easily detected by visual inspection in the manufacturing process of the intermediate transfer member. In addition, since a service person or a user can easily find a defect on the surface layer even without a skilled worker, it is possible to prevent a trouble of the apparatus such as an image defect beforehand.

Further, the present invention is an image forming apparatus having the above-mentioned intermediate transfer member.

With the above configuration, in an image forming apparatus which performs density detection on an intermediate transfer member, the detection accuracy of the density difference is improved for low to medium density toner images, and thus the accuracy of density control is improved. However, it is possible to obtain a printer output with a stable image density.

[0018]

[Embodiment 1] An embodiment according to the present invention will be described below.

FIG. 3 is a schematic sectional view of an electrophotographic color image forming apparatus (laser printer or copier) using an intermediate transfer member.

The apparatus applies electric charges to the photosensitive member 1, the primary charger 7, the laser exposure device 5, the developing devices 8, 9, the intermediate transfer member 2, the secondary transfer belt 3, the fixing device 12, and the developer on the intermediate transfer member. It is composed of a cleaning bias applying roller 4 which is a charging means for applying.

For example, the surface of the photoreceptor is uniformly charged to -550 V by the primary charger 7, and then the image pattern is exposed by a laser exposure device to form an electrostatic latent image. The exposed photoconductor surface has an unexposed partial potential (VD) of -550 V and an exposed partial potential (VL) of -180 V. The developing sleeve of the developing device is supplied with a
A developing bias of 350 V is applied, and the VL
The portion is developed with negatively charged negative toner, and the electrostatic latent image is visualized. The photosensitive member and the intermediate transfer member rotate at a constant speed, a primary transfer bias is applied to the intermediate transfer member, and the toner image on the photosensitive member is transferred to the photosensitive member 1 and the intermediate transfer member 2 at the primary transfer nip portion.
Is transferred to the intermediate transfer member 2 by the potential difference and the pressure.
By repeating the above process for the four color toners of yellow (Y), magenta (M), cyan (C), and black (K), an image in which four color plates overlap on the intermediate transfer body 2 is formed. . Next, the secondary transfer belt 3 is attached to the intermediate transfer body 2.
Is pressed, a secondary transfer bias is applied, and at the same time, when paper or the like is passed as the transfer material P, the toner image is transferred to the paper. When the paper passes through the fixing device 12, the toner image is fixed on the paper at the same time as the color mixture, and a full-color image is obtained.

FIG. 1 shows the intermediate transfer member 2 according to the present invention. The support is composed of a metal core L1 made of metal such as aluminum and an elastic layer L2 having a thickness of 5 mm. For example, urethane rubber is selected as the elastic layer L2, and carbon black is mixed as a reinforcing agent or in order to satisfy electrical characteristics. In this embodiment, by further mixing titanium oxide so as to adjust the surface to have a medium gray color, defects such as scratches and peeling of the surface can be easily detected by visual observation.

[Embodiment 2] Another embodiment of the present invention will be described below.

Description of items common to the first embodiment is omitted.

In this embodiment, a density detecting means is provided on the intermediate transfer member to control the density of an output image. An optical sensor 13 is disposed between the primary transfer position and the secondary transfer position on the intermediate transfer member. The optical sensor 13 includes a pair of a light emitting element and a light receiving element. The light receiving element detects reflected light of light emitted from the light emitting element toward the surface of the intermediate transfer member. When the toner image is formed on the intermediate transfer member, the output voltage of the light receiving element is equivalent to the sum of the densities of the intermediate transfer member and the toner image. The output value with the reflected light from the obtained toner image is obtained, and the density of the patch formed on the intermediate transfer body is obtained from the difference between the output signal values.
The developing bias output value is corrected so as to obtain the desired density.

FIG. 4 is a graph showing the relationship between the toner image formed on the intermediate transfer member and the output voltage of the light receiving element when the reflection density on the surface of the intermediate transfer member is a dark color such as around 1.0. In this case, since the range of the output voltage is narrow, the resolution with respect to the density is low, and the accuracy of the density control is low.

In this embodiment, as shown in FIG. 2, the elastic layer L2 of the intermediate transfer member 2 is made of fluorine rubber, and carbon black is mixed as a resistance adjuster. In this embodiment, as the surface layer L3, a light gray paint obtained by mixing, for example, a fluororesin with titanium oxide was applied at a thickness of 10 μm, and the reflection density of the surface was set at around 0.6, as shown in the graph of FIG. Therefore, the range of the output voltage value is widened, the detection accuracy of a low density portion particularly sensitive to human eyes is improved, and the stability of the halftone density during the density control can be expected.

Further, since the color is achromatic without having a specific color, the sensor output values for the yellow, magenta and cyan toner images are not biased depending on the color.

Further, since the surface is colored by painting, the color can be adjusted without affecting the electric characteristics of the elastic layer L2.

[Embodiment 3] A third embodiment of the present invention will be described.

The description of items common to the first embodiment is omitted.

FIG. 2 shows the intermediate transfer member 2 in this embodiment. As the elastic layer L2, nitrile butadiene rubber (NB
R) is selected, carbon black is mixed as a reinforcing agent or to satisfy electrical characteristics, and titanium oxide is further mixed so that the reflection density of the surface is in the range of 0.2 to 0.8. It was adjusted. In this embodiment, the surface layer L3 is coated with a colorless fluororesin of 10 μm. This makes it possible to increase the releasability of the surface layer of the intermediate transfer member, reduce dirt on the intermediate transfer member, and durably maintain the density of the intermediate transfer member.

In the embodiments described so far, the intermediate transfer drum has been described as an example. However, the present invention is not limited to a drum-shaped intermediate transfer member, and the same effect can be obtained with a belt-shaped intermediate transfer member. . Although the belt transfer method is used as the secondary transfer means, the effect of the present invention does not change even if a conventional corona transfer or transfer roller method is used.

In the present embodiment, the negative process is described as an example, but the present invention is also applicable to a positive process.

The material of the intermediate transfer member and the thicknesses of the elastic layer and the surface layer are not limited to those of the present embodiment, and similar effects can be obtained by optimizing each system.

Although the method of coating is not specified, any method such as dipping or spray coating may be used.

[0037]

As described above, according to the intermediate transfer member of the present invention, defects such as scratches and peeling of the surface layer can be easily detected by visual inspection in the process of manufacturing the intermediate transfer member.

Further, since a service person or a user can easily find a defect on the surface layer even without a skilled worker, it is possible to prevent troubles in the apparatus such as image defects.

In particular, the reflection density of the surface after coloring is 0.2
In the image forming apparatus that performs density detection on the intermediate transfer member by setting the range to 0.8, the accuracy of density control can be improved by improving the detection accuracy of the density difference between the low density and the medium density toner images. It is possible to obtain a printer output with improved image density.

Further, by making the color after coloring an achromatic color, the output value of the density detection sensor is not biased for each toner color, which leads to an improvement in the accuracy and stability of density control.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of another embodiment of the present invention.

FIG. 3 is a schematic sectional view of an image forming apparatus having an intermediate transfer member of the present invention.

FIG. 4 shows a relationship between a toner image density and a light receiving element output value.

FIG. 5 shows a relationship between a toner image density and a light receiving element output value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 Intermediate transfer member 3 Secondary transfer belt 4 Bias applying roller 5 Laser exposure device 6 Cleaner 7 Primary charging roller 8 Black developing device 9 Color developing device 12 Fixing device 13 Optical sensor 14 Bias power supply 16 CPU L1 Support L2 Elasticity Layer L3 Surface P Transfer material

Claims (6)

[Claims] 1. An image formed on a first image carrier is primary-transferred sequentially from a first color to a plurality of colors on an intermediate transfer body as a second image carrier, and then formed on the intermediate transfer body. In the intermediate transfer body used in a color image forming apparatus that obtains a color image by collectively secondary transferring the transferred image to a transfer material, a material constituting the intermediate transfer body contains a paint, and is colored. Intermediate transfer member. 2. An image formed on a first image carrier is primary-transferred sequentially from a first color to a plurality of colors on an intermediate transfer body as a second image carrier, and then formed on the intermediate transfer body. In the intermediate transfer body used in a color image forming apparatus that obtains a color image by collectively and secondarily transferring the formed image to a transfer material, the surface of the intermediate transfer body is coated with a paint and colored. Intermediate transfer member. 3. The intermediate transfer member according to claim 1, wherein the color after coloring is achromatic. 4. The intermediate transfer member according to claim 1, wherein a colorless coating is applied to the surface after coloring. 5. The intermediate transfer member according to claim 1, wherein the surface has a reflection density of 0.2 to 0.8. 6. An image forming apparatus comprising the intermediate transfer member according to claim 1.