JPH1195567A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of forming a stable image of high quality by suppressing the damage caused by long use of an intermediate transfer body and a member abutted thereon, to a level as low as possible. SOLUTION: The image forming device is provided with a latent image forming means for forming an electrostatic latent image on an image carrier uniformly charged by an electrifying means, a developing means for developing the electrostatic latent image, to form an actual image, the intermediate transfer belt (intermediate transfer body) 11 as a medium to which the actual image is transferred, a transfer means for transferring the actual image on the belt 11 to a transfer material and a fixing means for fixing the actual image on the transfer material. In the image forming device, the intermediate transfer body 11 is revolved in a direction where a coefficient of friction with a cleaning blade 16 abutted on the surface of the intermediate transfer body 11 is small. Thus, the edge chipping, wearing, rolling up, etc., of the cleaning blade 16 can be prevented, the damage to the belt 11 can be suppressed as little as possible and the driving torque of a device can be suppressed comparatively low and stabilized as well.

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 provided with an intermediate transfer member or a transfer material carrier.

[0002]

2. Description of the Related Art Heretofore, a multicolor image forming apparatus provided with, for example, an intermediate transfer belt as a transfer member has been known, and its operation will be described below with reference to a schematic sectional view shown in FIG.

In FIG. 1, reference numeral 1 denotes a photosensitive drum 1 as an image carrier, and the surface of the photosensitive drum 1 is uniformly charged to, for example, -700 V by a primary corona charger 2. Thereafter, among the image components obtained by color-converting the respective color components of the document, first, the image exposure 3 of the magenta component is irradiated onto the photosensitive drum 1, and an electrostatic latent image is formed on the photosensitive drum 1.

The developing device is composed of developing devices 4a, 4b, 4c and 4d containing magenta, yellow, cyan and black developers, respectively. These developing devices 4a to 4d It is configured so that it can be separated.

[0005] The electrostatic latent image corresponding to the magenta component on the photosensitive drum 1 is developed by the magenta developing device 4a and visualized as a magenta toner image.

Next, the magenta toner image on the photosensitive drum 1 is primarily transferred to the intermediate transfer belt 11 by an electric field generated by a bias applied to the primary bias roller 8. Thereafter, image exposure, development, and primary transfer to the intermediate transfer belt 11 corresponding to each color of yellow, cyan, and black are sequentially repeated, so that toner images of four colors are multiplex-transferred to the intermediate transfer belt 11. During this time, the intermediate transfer belt 1
The cleaning blade 16 and the secondary transfer bias roller 12, which are the first cleaning means, are separated from the intermediate transfer belt 11.

On the other hand, the transfer material P is fed at a predetermined timing, and the multi-toner image on the intermediate transfer belt 11 is collectively transferred onto the transfer material P by the electric charge due to the bias applied to the secondary transfer bias roller 12. Is done. Then, the transfer material P having received the transfer of the multiplex toner image is conveyed to the fixing device 14 by the conveying belt 13 and heated and pressed by passing between the fixing roller 14a and the pressure roller 14b of the fixing device 14. The multi-toner image is fixed, thereby obtaining a color image.

The transfer residual toner remaining on the photosensitive drum 1 after the primary transfer of the toner image of each color to the intermediate transfer belt 11 is removed by the cleaning device 5, and the photosensitive drum 1 is exposed to light by the pre-exposure lamp 15. Is discharged to be used for image formation of the next color.

A developing device 4a is provided on the intermediate transfer belt 11.
To 4d or the like, toner remaining as it is when the transfer material P is jammed in the middle of the transfer material, secondary transfer residual toner remaining at the time of secondary transfer, etc.
These toners are removed by the cleaning blade 16.

On the other hand, an image forming apparatus using a transfer belt as a transfer material carrier is used.
This will be described below based on the schematic sectional view shown in FIG.

In FIG. 1, reference numeral 1 denotes a photosensitive drum 1 serving as an image carrier, and the surface of the photosensitive drum 1 is uniformly charged to, for example, -700 V by a primary corona charger 2. Thereafter, a laser exposure 3, which is an image exposure corresponding to the original, is irradiated onto the photosensitive drum 1 to form an electrostatic latent image on the photosensitive drum 1.

Next, the electrostatic latent image is developed by the developing device 4 to be visualized as a toner image. The toner image is exposed to the transfer material P fed at a predetermined timing from the back side of the transfer belt 21. The image is transferred by a bias roller 12 arranged opposite to the drum 1. Incidentally, a bias is applied to the bias roller 12 from a high voltage power supply 20.

The transfer material P to which the toner image has been transferred
Is conveyed to the fixing device 14, and the fixing device 14 fixes the toner image to obtain a final image.

The transfer residual toner remaining on the photosensitive drum 1 is removed by a drum cleaning device 5, and the residual potential is removed by irradiation of light from a pre-exposure lamp 15 to prepare for the next image formation.

On the other hand, the developing device 4
The toner scattered from the transfer material P and the toner which is transferred when the transfer material P causes a paper jam on the way may adhere thereto. These are removed by cleaning means such as the cleaning blade 16 and the back surface of the transfer material P. , And a decrease in electrostatic attraction force between the transfer belt 21 and the transfer material P can be prevented.

[0016]

The image forming apparatus using an intermediate transfer belt as an intermediate transfer member has the following problems.

That is, when the polishing process is included in the manufacturing process of the intermediate transfer belt, when the surface is enlarged, the surface shape is not uniform, and irregularities are likely to occur in a certain direction.

FIG. 2 shows an enlarged cross section of the intermediate transfer belt 11. The intermediate transfer belt 11 has a two-layer structure including a base layer 11a and a surface layer 11b. Even if the surface of the intermediate transfer belt 11 having such a configuration is polished to keep the thickness of the base layer 11a and the surface shape constant, the cross section is enlarged as shown in FIG. The surface of the base layer 11a has irregularities, and the surface layer 1
1b, the surface layer 11b usually has a thickness of 5 to 30 μm.
Since it is as thin as about m, the surface roughness of the lower base layer 11a tends to affect the shape of the surface 11b.

The following problems are likely to occur due to the surface roughness of the intermediate transfer member as described above.

As a cleaning device for the intermediate transfer belt or the like, a cleaning blade is often used from the viewpoint of simplicity of configuration and low cost. In this case,
If the surface roughness of the surface of the intermediate transfer belt is large, the edge of the tip of the cleaning blade is caught and chipping or polishing of the edge is likely to occur, resulting in poor cleaning,
Since the residual toner is secondarily transferred as a part of the image as it is, in many cases, a vertical line is formed on the transfer material, and the image quality is greatly reduced.

Further, it is possible that the cleaning blade is turned up to cause a partial or entire cleaning failure. In such a case, in addition to the above-described problems, the driving torque of the intermediate transfer belt also increases due to an increase in the contact area between the cleaning blade and the intermediate transfer belt and an increase in the pressing force. This causes a situation in which the operation itself of the apparatus stops, and the operation itself of the apparatus stops.

Usually, when polishing a belt-shaped object,
Since a disk-shaped grindstone rotating while the belt is fitted in a cylindrical mold is brought into contact with the belt and polished, irregularities having micro-directionality are formed on the polished surface of the belt surface. Therefore, when the polishing direction on the intermediate transfer belt 11 matches the direction in which the coefficient of friction with respect to the cleaning blade 16 increases as shown in FIG.

Problems such as wear on the surface of the intermediate transfer belt, small cracks, and peeling of the surface layer due to friction between the intermediate transfer belt and a contact member such as a cleaning blade are likely to occur. This phenomenon is more remarkable when the intermediate transfer belt rotates in a direction in which the friction coefficient increases with respect to a member that comes into contact with the intermediate transfer belt, as in the case described above, in which the unevenness of the surface of the belt has directionality. Easy to occur.

Since the driving torque of the intermediate transfer belt is large and unstable, it is necessary to provide a margin for the torque of a motor for driving the apparatus.

The above problem can be solved by reducing the surface roughness of the intermediate transfer belt to a level that does not cause any problem. However, the polishing time is lengthened, the grain size of the grindstone is initially coarse, and Since it is necessary to reduce the size or increase the number of steps, the cost is increased. or,
In the case where the object to be polished is a rubber, the polishing ability is particularly limited.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to form a high-quality and stable image by minimizing damage due to durability of an intermediate transfer member and members abutting the intermediate transfer member. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

Also, the image forming apparatus shown in FIG. 7 using a transfer belt as a transfer material carrier has the same problem as the image forming apparatus shown in FIG. 1 using an intermediate transfer belt as an intermediate transfer member. .

Accordingly, an object of the present invention is to provide an image forming apparatus capable of forming a high-quality and stable image by minimizing damage due to durability of a transfer material carrier and a member abutting thereon. It is in.

[0029]

In order to achieve the above object, the present invention is directed to a latent image forming means for forming an electrostatic latent image on an image carrier uniformly charged by a charging means. Developing means for developing the electrostatic latent image to form a visible image, an intermediate transfer member as a medium to which the visible image is transferred, and transferring the visible image on the intermediate transfer member to a transfer material And an image forming apparatus having a fixing unit for fixing a visible image to a transfer material, wherein the intermediate transfer body is rotated in a direction having a small friction coefficient with respect to a member abutting on the surface of the intermediate transfer body. Features.

According to a second aspect of the present invention, in the first aspect of the present invention, the surface of the intermediate transfer member is polished.

According to a third aspect of the present invention, in the first or second aspect of the invention, the intermediate transfer member has a multilayer structure of two or more layers.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a friction coefficient of a surface layer of the intermediate transfer member is made smaller than a friction coefficient of a layer inside the surface layer.

According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, the surface layer of the intermediate transfer member contains a fluorine resin.

According to a sixth aspect of the present invention, in the first to fourth or fifth aspects, the intermediate transfer member is an endless belt-shaped intermediate transfer belt.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, any one of the layers of the intermediate transfer belt contains rubber or an elastomer.

According to an eighth aspect of the present invention, in the first to fourth or fifth aspects, the intermediate transfer member is an endless drum-shaped intermediate transfer drum.

A ninth aspect of the present invention is characterized in that, in the eighth aspect of the present invention, any one of the layers of the intermediate transfer drum includes a rubber, an elastomer, or a sponge layer.

According to a tenth aspect of the present invention, there is provided a latent image forming means for forming an electrostatic latent image on an image carrier which is uniformly charged by a charging means, and developing the electrostatic latent image to form a visible image. Developing means for forming, a transfer material carrier for electrostatically transferring the developed image to a transfer material in a nip portion between the image carrier and transporting the transfer material, and transferring the developed image to the transfer material. In an image forming apparatus having a fixing unit for fixing, the transfer material carrier is rotated in a direction having a smaller coefficient of friction with respect to a member abutting on the surface of the transfer material carrier.

According to an eleventh aspect of the present invention, in the invention of the tenth aspect, the surface of the transfer material carrier is polished.

According to a twelfth aspect of the present invention, in the tenth or eleventh aspect, the transfer material carrier has a multilayer structure of two or more layers.

According to a thirteenth aspect, in the twelfth aspect, the friction coefficient of a surface layer of the transfer material carrier is made smaller than a friction coefficient of a layer inside the surface layer.

According to a fourteenth aspect, in the twelfth or thirteenth aspect, the base layer of the transfer material carrier is made of rubber or elastomer.

According to a fifteenth aspect of the present invention, in the twelfth or thirteenth aspect, the surface layer of the transfer material carrier contains a fluorine-based resin.

Therefore, according to the first aspect of the present invention, the intermediate transfer member is rotated in a direction having a small coefficient of friction with respect to a member abutting the surface of the intermediate transfer member. , Abrasion, turning over, and the like, damage to the intermediate transfer member can be suppressed to a small value, and the driving torque of the apparatus can be suppressed to a relatively low value to stabilize the device.

According to the second aspect of the present invention, by polishing the surface of the intermediate transfer member, the thickness of the intermediate transfer member can be made constant, and the surface roughness can be reduced.

According to the third aspect of the present invention, since the intermediate transfer member has a multi-layer structure, various functions can be separately provided in each layer, and the intermediate transfer member can be constituted by an optimum material suitable for the purpose. .

According to the fourth aspect of the present invention, since the friction coefficient of the surface layer of the intermediate transfer member is smaller than the friction coefficient of the layer inside the surface layer, the intermediate transfer member can be driven stably without slip. .

According to the fifth aspect of the present invention, since the surface layer of the intermediate transfer member contains a fluorine-based resin, the releasability of the intermediate transfer member from toner and paper powder and the cleaning property are enhanced.

According to the sixth aspect of the present invention, since the intermediate transfer member is an endless belt-shaped intermediate transfer belt, the degree of freedom of arrangement in the main body of the image forming apparatus is increased, and the intermediate transfer belt in the secondary transfer portion is provided. Can be set large, so that the transfer material can be prevented from electrostatically sticking to the intermediate transfer belt.

According to the seventh aspect of the present invention, since any layer of the intermediate transfer belt contains rubber or elastomer, friction between the intermediate transfer belt and a pulley (particularly, a driving pulley) that stretches the intermediate transfer belt is provided. The force is increased, and the intermediate transfer belt can be driven stably without slipping. In addition, since the intermediate transfer belt has appropriate elasticity, the deviation of the transfer material carrier can be controlled without adding a special device. be able to.

According to the ninth aspect of the present invention, since any one of the layers of the intermediate transfer drum contains a rubber, an elastomer, or a sponge layer, the surface of the intermediate transfer drum can be given an appropriate elasticity. As a result, an appropriate nip width can be secured in the primary and secondary transfer portions, and damage due to contact between the intermediate transfer drum and the image carrier can be suppressed.

According to the tenth aspect of the present invention, the transfer material carrier is rotated in a direction in which the coefficient of friction is smaller with respect to a member abutting the surface of the transfer material carrier. , Abrasion, turning over, and the like, damage to the transfer material carrier can be suppressed to a small value, and the driving torque of the apparatus can be suppressed to a relatively low level to stabilize the apparatus.

According to the eleventh aspect, by polishing the surface of the transfer material carrier, the thickness of the transfer material carrier can be made constant, and the surface roughness can be kept small.

According to the twelfth aspect of the present invention, since the transfer material carrier has a multi-layer structure, various functions can be separately provided in each layer, and the transfer material carrier can be constituted by an optimum material suitable for the purpose. Can be.

According to the thirteenth aspect, the friction coefficient of the surface layer of the transfer material carrier is made smaller than the friction coefficient of the layer inside the surface layer, so that the transfer material carrier can be driven stably without slip. Becomes

According to the fourteenth aspect of the present invention, since the base layer of the transfer material carrier is made of rubber or elastomer, the frictional force between the transfer material carrier and the pulley (particularly the drive pulley) that stretches the transfer material carrier is large. As a result, the transfer material carrier can be driven stably without slipping, and the transfer material carrier has an appropriate elasticity, so that the deviation of the transfer material carrier can be controlled without adding a special device. be able to.

According to the fifteenth aspect of the present invention, since the surface layer of the transfer material carrier contains a fluorine resin, the releasability and cleaning property of the transfer material carrier against toner and paper dust are enhanced. Can be

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION

[First invention] An embodiment of the first invention will be described below with reference to the accompanying drawings.

<First Embodiment> The first embodiment of the present invention can be suitably implemented in the image forming apparatus shown in FIG.
The operation of the image forming apparatus shown in FIG. 1 is the same as described above, and the description thereof will not be repeated here.

In the image forming apparatus shown in FIG. 1, reference numeral 11 denotes an intermediate transfer belt, and reference numeral 16 denotes a cleaning blade for the intermediate transfer belt 11. As shown in FIG. 2, the intermediate transfer belt 11 is formed by polishing the surface of a rubber base layer 11a to have a constant thickness, and then coating the surface with a surface layer 11b. In the intermediate transfer belt 11 having a two-layer structure including the base layer 11a and the surface layer 11b, the friction coefficient of the surface layer 11b is set smaller than that of the base layer 11a.

Here, the base layer 1 of the intermediate transfer belt 11
EPDM rubber, chloroprene rubber,
Epichlorohydrin rubber, silicone rubber, NBR rubber, and modified rubbers thereof are used. As the material of the surface layer 11b, a material containing a fluororesin (for example, a material containing PVDF, PTFE, tetrafluoroethylene, etc.) is used from the viewpoint of high releasability and low friction coefficient.

In this embodiment, EPDM rubber is used for the base layer 11a of the intermediate transfer belt 11, and the base layer 11a is coated with a coating material in which a PVDF resin is dispersed to form a surface layer 11b. .

A cleaning blade 16 as a cleaning means for the intermediate transfer belt 11 was brought into contact with the intermediate transfer belt 11 in the counter direction. The cleaning blade 16 was made of polyurethane rubber.

The rotation direction of the intermediate transfer belt 11 was set in the direction indicated by the arrow in FIG. 4 so that the friction of the unevenness due to the polishing of the intermediate transfer belt 11 with respect to the cleaning blade 16 was reduced. The intermediate transfer belt 11
The pulleys 9, 10, and 19 are supported at both ends by bearings (not shown) so that sliding resistance is reduced.

In order to confirm the effect of the present embodiment, a durability comparison was made between the case shown in FIG. 4 and the case shown in FIG. Table 1 shows the results.

[0066]

In Table 1, the number of durable sheets is obtained by intermittently forming an image of A4 width one sheet, and K means 1000 (for example, 10K means 10,000 sheets). As for the cleaning failure of the evaluation item, the cleaning state was evaluated by rotating the intermediate transfer belt while the magenta toner was uniformly placed on the intermediate transfer belt. The durability was performed under two kinds of environments: normal temperature and low humidity (N / L) and high temperature and high humidity (H / H).

When the rotation direction of the intermediate transfer belt is in the order of decreasing the friction coefficient with respect to the contact of the cleaning blade, cleaning failure did not occur up to 70K in a normal temperature and low humidity (N / L) environment. In the case of eyes, slight cleaning failure occurred at 60K. At this time, when the edge of the cleaning blade was observed with a microscope, small chips were found, and peeling of the surface layer was partially confirmed on the intermediate transfer belt. This phenomenon is caused by high temperature and high humidity (H /
H) Accelerated in the environment, occurring at 40K in the converse.

The turning-up of the blade did not occur normally in a normal temperature and low humidity (N / L) environment, but occurred at a temperature of 80 K in a reverse direction, and did not occur in a high temperature and high humidity (H / H) environment. It did not occur, but it occurred at 60K in the reverse order. This is considered to be caused by high frictional resistance between the intermediate transfer belt and the cleaning blade due to moisture between the intermediate transfer belt and the cleaning blade in a high temperature and high humidity (H / H) environment.

As can be seen from the above description, in an image forming apparatus using an intermediate transfer belt, if the intermediate transfer belt is driven to rotate in a direction having a smaller coefficient of friction with respect to the cleaning blade that comes into contact with the belt, the edge of the cleaning blade is Chipping, abrasion, turning over, and damage to the intermediate transfer belt can be suppressed.

<Second Embodiment> Next, a second embodiment of the first invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the main part of the image forming apparatus according to the present embodiment. In FIG. 5, the same elements as those shown in FIG. Omitted.

In this embodiment, an intermediate transfer drum 17 is used as an intermediate transfer member, and the other configuration is the same as that shown in FIG. Note that any layer of the intermediate transfer drum 17 includes a rubber, elastomer, or sponge layer.

By forming the intermediate transfer member by the intermediate transfer drum 17 as in the present embodiment, the deviation and the driving of the belt can be reduced as compared with the case where the intermediate transfer member is formed by a belt-like member. There is no possibility of slippage with the pulley.

When the belt partially expands and contracts due to its driving and load, the toner image of each color is slightly shifted and transferred in a multiplex manner. However, such a problem can be solved by forming the intermediate transfer member with the drum-shaped intermediate transfer drum 17 as in the present embodiment.

In the present embodiment, the edge of the cleaning blade 16 is chipped, worn, and turned up by rotating the intermediate transfer drum 17 in a direction in which the coefficient of friction is reduced with respect to the cleaning blade 16 in contact therewith. And damage to the intermediate transfer drum 17 can be suppressed.

<Third Embodiment> Next, a third embodiment of the first invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of a main part of the image forming apparatus according to the present embodiment. In this figure, the same elements as those shown in FIG. Omitted.

In the first and second embodiments, the cleaning blade is used as the cleaning means for the intermediate transfer member. However, in this embodiment, the fur brush 18 is used as the cleaning means for the intermediate transfer belt 11 as shown in FIG. Is used.

Various materials can be used as the material of the fur brush 18. In this embodiment, rayon in which carbon is dispersed is used. It is configured to rotate.

Although the fur brush 18 is higher in cost than a blade, development such as turning up of the blade does not occur, and a fatal problem with respect to the operation of the image forming apparatus hardly occurs.

The fur brush 18 makes it easy for the charged toner to separate from the intermediate transfer belt 11 by being electrically biased or dropped to the ground. However, the toner alone cannot completely remove the toner. is there. For example, when image formation is continuously performed in a low-humidity environment, the toner in the developing units 4a to 4d is frictionally charged and the toner cannot be removed if the charge amount increases,
The toner has adhered to the intermediate transfer belt 11 with a large electrostatic attraction force.

In the case where the image forming operation is stopped due to the paper jam of the transfer material P after the multi-transfer of the four colors of toner on the intermediate transfer belt 11, a large amount of toner needs to be cleaned. There is. In such a case, the density of the fur brush 18 is increased,
To make the fibers thicker or harder, to increase the speed,
Alternatively, the cleaning performance can be improved by increasing the amount of the fur brush 18 biting into the intermediate transfer belt 11.

However, the measures described above naturally increase the damage to the intermediate transfer belt 11. Therefore, even when cleaning is performed using the fur brush 18, the damage to the intermediate transfer belt 11 can be suppressed by rotating the intermediate transfer belt 11 in a direction in which the friction coefficient decreases with respect to the rotating fur brush 18. Can be.

In the above embodiment, the case where the cleaning blade and the fur brush are used as the members that contact the intermediate transfer member has been described. However, the members that contact the intermediate transfer member are not limited thereto. Instead, for example, the present invention can be similarly applied to a case where a static elimination member for the intermediate transfer belt or a pressure roller for maintaining tension is employed. [Second invention] An embodiment of the second invention will be described below with reference to the accompanying drawings.

<Embodiment 1> Embodiment 1 of the present invention can be suitably implemented in the image forming apparatus shown in FIG.
The operation of the image forming apparatus shown in FIG. 7 is the same as described above, and a description thereof will not be repeated here.

In the image forming apparatus shown in FIG. 7, 21 is a transfer belt, and 16 is a cleaning blade for the transfer belt 21. As shown in FIG. 8, the transfer belt 21 is configured such that the surface of a rubber base layer 21a is polished so as to have a constant thickness, and the surface is coated with a surface layer 21b. In the transfer belt 21 having a two-layer structure including the base layer 21a and the surface layer 21b, the surface layer 2
The friction coefficient of 1b is set smaller than that of the base layer 21a.

Here, the base layer 21a of the transfer belt 21
EPDM rubber, chloroprene rubber, epichlorohydrin rubber, silicone rubber, NBR rubber, and modified rubbers thereof are used as the material. As the material of the surface layer 21b, a material containing a fluororesin (for example, a material containing PVDF, PTFE, ethylene tetrafluoride, or the like) is used from the viewpoint of high releasability and low friction coefficient. The transfer belt 2
1 is polished.

In the present embodiment, the base layer 21a of the transfer belt 21 is made of EPDM rubber, and the base layer 21a is coated with a paint in which a PVDF resin is dispersed to form the surface layer 21b.

The cleaning blade 16 as a means for cleaning the transfer belt 21 was brought into contact with the transfer belt 21 in the counter direction. Incidentally, polyurethane rubber was used as a material of the cleaning blade 21.

The rotation direction of the transfer belt 21 is shown in FIG.
As shown in FIG. 0, the direction of the arrow is set so that the friction of the unevenness due to the polishing of the transfer belt 21 with respect to the cleaning blade 16 is reduced. The pulleys 9 and 10 on which the transfer belt 21 is stretched are supported at both ends by bearings (not shown) so that sliding resistance is reduced.

Thus, in order to confirm the effect of the present embodiment, a durability comparison was made between the case shown in FIG. 10 and the case shown in FIG. Table 2 shows the results.

[0090]

In Table 2, the number of durable sheets is obtained by intermittently forming an image of A4 width on one sheet, and K means 1000 (for example, 10K means 10,000 sheets). As for the cleaning failure of the evaluation item, the cleaning state was evaluated by rotating the transfer belt in a state where the toner was intentionally placed uniformly on the transfer belt.

Further, each time the drive load torque was measured, only the transfer belt unit (with a cleaning blade) was taken out of the main body of the image forming apparatus and measured with a torque gauge. The durability was performed under two kinds of environments: normal temperature and low humidity (N / L) and high temperature and high humidity (H / H).

In the case where the rotation direction of the transfer belt is in the order of decreasing the friction coefficient with respect to the contact of the cleaning blade,
50 cleaning failures under normal temperature and low humidity (N / L) environment
K did not occur, but in the case of reverse, slight cleaning failure occurred at 40K. At this time, when the edge of the cleaning blade was observed with a microscope, small chips were found, and peeling of the surface layer was partially confirmed on the transfer belt. This phenomenon was accelerated in a high-temperature, high-humidity (H / H) environment, and occurred at 20 K in a reverse order.

[0093] In addition, the blade turn-up did not occur under the normal temperature and low humidity (N / L) environment, but occurred under the high temperature and high humidity (H / H) environment at 31 K at a reverse angle. This is considered to be caused by high frictional resistance between the transfer belt and the cleaning blade in a high temperature and high humidity (H / H) environment due to moisture between the transfer belt and the cleaning blade.

On the other hand, the driving load torque of the transfer belt unit is larger in the reverse direction than in the normal direction, and is lower than normal temperature and low humidity (N /
L) High temperature / humidity (H / H) is larger than under the environment. The latter development is due to the large friction coefficient between the transfer belt and the cleaning blade as described above. Also, the reason why the driving load torque is increased in durability is considered that a part of the convex portion is cut off due to friction on the surface of the transfer belt and the contact area with the cleaning blade is increased.

As can be seen from the above description, in an image forming apparatus using a transfer belt, if the transfer belt is driven to rotate in a direction with a smaller coefficient of friction with respect to the cleaning blade abutting on the transfer belt, the edge of the cleaning blade may be cut off. Abrasion, turning over and damage to the transfer belt can be suppressed.

<Second Embodiment> Next, a second embodiment of the second invention will be described with reference to FIG. FIG. 11 is a sectional view of a main part of the multicolor image forming apparatus.

The present invention is applicable to a multi-color image forming apparatus of a type in which a plurality of photosensitive drums are arranged as shown in FIG.

In FIG. 5, reference numerals 1a, 1b, 1c, and 1d denote photosensitive drums, which are not shown. Around the respective photosensitive drums 1a to 1d, a primary charger and an image exposing device are provided as shown in FIG. , A developing device, a drum cleaner, and the like.

In the present multicolor image forming apparatus, after the original is separated into colors, the photosensitive drums 1a to 1d are irradiated with image exposures corresponding to the magenta, yellow, cyan and black components, respectively, to form a latent image. Each latent image is magenta,
The toner images are developed with yellow, cyan, and black toners, and the respective toner images are sequentially transferred onto the transfer material P in a superimposed manner to obtain a color image.

Thus, also in the present embodiment, the same configuration as in the first embodiment can be adopted, and the same effect as in the first embodiment can be obtained.

Third Embodiment Next, a third embodiment of the second invention will be described with reference to FIG. FIG. 12 is a sectional view of a main part of the multicolor image forming apparatus.

The present invention is applicable to a multicolor image forming apparatus as shown in FIG.

As shown in FIG. 12, four developing units 4a, 4b, 4c and 4d are arranged around the photosensitive drum 1, and magenta, yellow, cyan and black toners are provided in each of the developing units 4a to 4d. Are stored respectively.

In the present multicolor image forming apparatus, a latent image is formed on the photosensitive drum 1 by image exposure corresponding to magenta, and this latent image is developed as a magenta toner image by the magenta developing unit 4a. At this time, the other developing device 4
b to 4 d are separated from the photosensitive drum 1. Thereafter, similarly, yellow, cyan, and black toner images are sequentially developed on the photosensitive drum 1, and these toner images are collectively transferred to a transfer material fed at a predetermined timing.

Thus, also in the present embodiment, it is possible to adopt the same configuration as in the first and second embodiments.
The same effects as in the first and second embodiments can be obtained.

<Fourth Embodiment> Next, a fourth embodiment of the second invention will be described with reference to FIG. FIG. 13 is a cross-sectional view of a main part of the image forming apparatus according to the present embodiment. In this figure, the same elements as those shown in FIG. Omitted.

In the first to third embodiments described above, the cleaning blade is used as a cleaning means for the transfer material carrier such as the transfer belt.
The fur brush 18 is used as a cleaning means for the transfer belt 21 as shown in FIG.

Various materials can be used for the fur brush 18. In this embodiment, rayon in which carbon is dispersed is used, and the fur brush 18 is moved in the counter direction with respect to the transfer belt 21. It was configured to rotate.

Although the fur brush 18 is higher in cost than the blade, development such as turning up of the blade does not occur, and a fatal problem with respect to the operation of the image forming apparatus hardly occurs.

The fur brush 18 is electrically biased or dropped to ground so that the charged toner is easily separated from the transfer belt 21. However, the toner may not be completely removed by itself. . For example, when image formation is continuously performed in a low humidity environment, the developing device 4
When the toner in a to 4d is frictionally charged and the amount of charge increases, the toner cannot be removed, and the toner adheres to the transfer belt 21 with a large electrostatic attraction force.

In such a case, the density of the fur brush 18 is increased, the fiber of the fur brush 18 is made thicker or harder, the speed is increased, or the fur brush 18 bites into the transfer belt 21. It is possible to improve the cleaning performance by increasing.

However, such measures as described above naturally increase the damage to the transfer belt 21. Therefore, even when cleaning is performed using the fur brush 18, damage to the transfer belt 21 can be suppressed by rotating the transfer belt 21 in a direction in which the friction coefficient decreases with respect to the rotating fur brush 18. .

The fur brush can be used instead of a cleaning blade as a transfer belt cleaning means in the multicolor image forming apparatus shown in FIGS.

Further, in the above embodiment, the case where the cleaning blade and the fur brush are used as the members that contact the transfer material carrier has been described, but the members that contact the transfer material carrier are not limited thereto. For example, the present invention can be similarly applied to a case where a charge removing member of a transfer belt, a pressure roller for maintaining tension, or the like is employed.

[0115]

As is apparent from the above description, claim 1
According to the invention described above, the intermediate transfer member is rotated in a direction having a small coefficient of friction with respect to a member abutting the surface of the intermediate transfer member. Thus, it is possible to obtain an effect that the damage to the intermediate transfer member can be suppressed to a small value, and the driving torque of the apparatus can be suppressed to a relatively low value to stabilize the device.

According to the second aspect of the present invention, by polishing the surface of the intermediate transfer member, it is possible to make the thickness of the intermediate transfer member constant and to suppress the surface roughness to a small value.

According to the third aspect of the present invention, since the intermediate transfer member has a multi-layer structure, various functions can be separately provided in each layer, and the intermediate transfer member can be constituted by an optimum material suitable for the purpose. The effect is obtained.

According to the fourth aspect of the invention, since the friction coefficient of the surface layer of the intermediate transfer member is made smaller than the friction coefficient of the layer inside the surface layer, the intermediate transfer member can be driven stably without slip. The effect is obtained.

According to the fifth aspect of the present invention, since the surface layer of the intermediate transfer body contains a fluorine-based resin, the effect of improving the releasability and cleaning property of the intermediate transfer body against toner and paper dust is obtained. Can be

According to the sixth aspect of the present invention, since the intermediate transfer member is an endless belt-shaped intermediate transfer belt, the degree of freedom of arrangement in the main body of the image forming apparatus is increased, and the intermediate transfer belt in the secondary transfer portion is provided. Can be set large, so that the effect of preventing the transfer material from electrostatically sticking to the intermediate transfer belt can be obtained.

According to the present invention, since any layer of the intermediate transfer belt contains rubber or elastomer, friction between the intermediate transfer belt and a pulley (particularly, a driving pulley) that stretches the intermediate transfer belt is provided. The force is increased, and the intermediate transfer belt can be driven stably without slipping. In addition, since the intermediate transfer belt has appropriate elasticity, the deviation of the transfer material carrier can be controlled without adding a special device. The effect that it can be obtained is obtained.

According to the ninth aspect of the present invention, since any one of the layers of the intermediate transfer drum contains a rubber, an elastomer, or a sponge layer, the surface of the intermediate transfer drum can have an appropriate elasticity. As a result, an appropriate nip width can be secured in the primary and secondary transfer portions, and the effect of suppressing damage due to contact between the intermediate transfer drum and the image carrier can be obtained.

According to the tenth aspect of the present invention, the transfer material carrier is rotated in a direction in which the coefficient of friction is smaller with respect to a member abutting the surface of the transfer material carrier. In addition to preventing wear, turning over, and the like, damage to the transfer material carrier can be suppressed to a small value, and the driving torque of the apparatus can be suppressed to a relatively low value to stabilize the device.

According to the eleventh aspect, by polishing the surface of the transfer material carrier, the thickness of the transfer material carrier can be made constant and the surface roughness can be reduced.

According to the twelfth aspect of the present invention, since the transfer material carrier has a multi-layer structure, various functions can be separately provided in each layer, and the transfer material carrier can be constituted by an optimum material suitable for the purpose. Is obtained.

According to the thirteenth aspect, since the friction coefficient of the surface layer of the transfer material carrier is smaller than the friction coefficient of the layer inside the surface layer, the transfer material carrier can be driven stably without slip. Is obtained.

According to the fourteenth aspect of the present invention, since the base layer of the transfer material carrier is made of rubber or elastomer, the frictional force between the transfer material carrier and the pulley (particularly, the driving pulley) that stretches the transfer material carrier is large. As a result, the transfer material carrier can be driven stably without slipping, and the transfer material carrier has an appropriate elasticity, so that the deviation of the transfer material carrier can be controlled without adding a special device. The effect that it can be obtained is obtained.

According to the fifteenth aspect of the present invention, since the surface layer of the transfer material carrier contains a fluororesin, the releasability and cleaning property of the transfer material carrier against toner and paper dust are improved. Is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a partially enlarged cross-sectional view of an intermediate transfer belt.

FIG. 3 is a partial cross-sectional view illustrating a relationship between a surface shape (a reverse eye) of an intermediate transfer belt and a cleaning blade.

FIG. 4 is a partial cross-sectional view illustrating a relationship between a surface shape (first order) of an intermediate transfer belt and a cleaning blade.

FIG. 5 is a sectional view of a main part of a multicolor image forming apparatus according to a second embodiment of the first invention;

FIG. 6 is a sectional view of a main part of a multicolor image forming apparatus according to Embodiment 3 of the first invention.

FIG. 7 is a sectional view of a main part of the image forming apparatus according to the first embodiment of the second invention;

FIG. 8 is a partially enlarged cross-sectional view of the transfer belt.

FIG. 9 is a partial cross-sectional view showing a relationship between a surface shape (a reverse side) of the transfer belt and a cleaning blade.

FIG. 10 is a partial cross-sectional view illustrating a relationship between a surface shape (first order) of a transfer belt and a cleaning blade.

FIG. 11 is a sectional view of a main part of a multicolor image forming apparatus according to Embodiment 2 of the second invention.

FIG. 12 is a sectional view of a main part of a multicolor image forming apparatus according to Embodiment 3 of the second invention.

FIG. 13 is a sectional view of a main part of an image forming apparatus according to Embodiment 4 of the second invention;

[Explanation of symbols]

 1, 1a to 1d Photosensitive drum (image carrier) 2 Primary charger (charging means) 3 Image exposure (latent image forming means) 4 Developing device (developing means) 4a to 1d Developing device (developing means) 8, 12 Bias roller (Charging means) 11 Intermediate transfer belt (intermediate transfer body) 11a Base layer 11b Surface layer 14 Fixing device (fixing means) 16 Cleaning blade 17 Intermediate transfer drum (intermediate transfer body) 18 Fur brush 21 Transfer belt (transfer material carrier) 21a Base layer 21b Surface layer P Transfer material

[Table 1]

[Table 2]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 27:12

Claims (15)

[Claims] 1. A latent image forming means for forming an electrostatic latent image on an image carrier uniformly charged by a charging means, and a developing means for developing the electrostatic latent image to form a visible image And an intermediate transfer body as a medium to which the visible image is transferred, a transfer unit for transferring the visible image on the intermediate transfer body to a transfer material, and a fixing unit for fixing the visible image to the transfer material. The image forming apparatus according to claim 1, wherein the intermediate transfer body is rotated in a direction having a small coefficient of friction with respect to a member abutting the surface of the intermediate transfer body. 2. The image forming apparatus according to claim 1, wherein a surface of said intermediate transfer member is polished. 3. The image forming apparatus according to claim 1, wherein the intermediate transfer body has a multilayer structure of two or more layers. 4. The image forming apparatus according to claim 3, wherein a friction coefficient of a surface layer of the intermediate transfer member is smaller than a friction coefficient of a layer inside the surface layer. 5. The image forming apparatus according to claim 3, wherein the surface layer of the intermediate transfer member contains a fluorine resin. 6. The image forming apparatus according to claim 1, wherein the intermediate transfer member is an endless belt-shaped intermediate transfer belt. 7. The image forming apparatus according to claim 6, wherein one of the layers of the intermediate transfer belt contains rubber or an elastomer. 8. An image forming apparatus according to claim 1, wherein said intermediate transfer member is an endless drum-shaped intermediate transfer drum. 9. The image forming apparatus according to claim 8, wherein any one of the layers of the intermediate transfer drum includes a rubber, an elastomer, or a sponge layer. 10. A latent image forming means for forming an electrostatic latent image on an image carrier uniformly charged by a charging means, and a developing means for developing the electrostatic latent image to form a visible image When,
A transfer material carrier for electrostatically transferring the developed image to the transfer material at a nip portion between the image carrier and the transfer material, and a fixing unit for fixing the developed image to the transfer material; The image forming apparatus according to claim 1, wherein the transfer material carrier is rotated in a direction in which a coefficient of friction is small with respect to a member abutting the surface of the transfer material carrier. 11. The image forming apparatus according to claim 10, wherein a surface of said transfer material carrier is polished. 12. The image forming apparatus according to claim 10, wherein the transfer material carrier has a multilayer structure of two or more layers. 13. The image forming apparatus according to claim 12, wherein a friction coefficient of a surface layer of the transfer material carrier is smaller than a friction coefficient of a layer inside the surface layer. 14. The transfer material carrier according to claim 1, wherein the base layer is made of rubber or elastomer.
14. The image forming apparatus according to 2 or 13. 15. The transfer material carrier according to claim 12, wherein the surface layer of the transfer material carrier contains a fluorine-based resin.
3. The image forming apparatus according to 3.