JP3583282B2 - Color image forming equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus that forms a color image on a transfer sheet material such as transfer paper using a plurality of color toners.
[0002]
[Prior art]
As an intermediate transfer member of the first conventional color image forming apparatus, there is, for example, an intermediate transfer drum for a color image forming apparatus described in JP-A-4-287070. This conventional intermediate transfer drum for a color image forming apparatus is constructed by lining a conductive sponge on the outer peripheral surface of a metal drum, so that the photosensitive drum, the intermediate transfer drum, the transfer roller, etc. Eccentricity can be absorbed by deformation of the conductive sponge of the intermediate transfer drum, transmission of vibration to other parts can be prevented, and unevenness such as jitter can be prevented from occurring in output prints. It is described.
[0003]
As a second conventional color image forming apparatus, for example, there is an electrophotographic apparatus disclosed in Japanese Patent Application Laid-Open No. 5-150574. In the electrophotographic apparatus according to the second conventional example, the intermediate transfer member is formed by a loop belt (seamless belt) having no electric connection and is driven by a plurality of rollers. Is what it is.
[0004]
[Problems to be solved by the invention]
However, in the intermediate transfer drum for a color image forming apparatus according to the first conventional example, since the outer peripheral surface of the conductive sponge is covered with the conductive rubber, the surface roughness of the rubber is large, so that the toner image is not formed. Inferior in transferability, easily causing dropout or transfer scattering at the time of transfer, and the conductive rubber expands or contracts due to environmental temperature or heat, and color misregistration easily occurs between toner images of each color. There was a problem.
[0005]
Further, in the electrophotographic apparatus according to the second conventional example, since the intermediate transfer body is a seamless belt stretched over a plurality of rollers, color misregistration occurs due to meandering of the belt and fluctuation of rotation of the driving roller. If the assembly accuracy is increased to prevent this, the cost of the electrophotographic apparatus will be significantly increased. Further, when slippage occurs due to abrasion between the belt and the roller, the rotation also fluctuates, which also causes a color shift, which causes a problem that image quality is deteriorated and durability is deteriorated.
[0006]
In view of the above problems, an object of the present invention is to provide a color image forming apparatus that forms a high-quality image by preventing so-called voids and color shifts, and that is inexpensive and has excellent durability. Is what you do.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a color image forming apparatus according to the present invention includes a photosensitive member for forming an electrostatic latent image, and a developing device for developing the electrostatic latent image on the photosensitive member to form a toner image. A color image forming apparatus comprising: an intermediate transfer member configured to perform multiple transfer of a plurality of color toner images from the photoconductor; and a transfer device configured to perform secondary transfer of the multiple transferred toner image to a transfer sheet material. A body formed of a cylinder and having conductivity; a sponge-shaped conductive elastic body provided concentrically laminated outside the cylinder base; and a concentric circular outside the conductive elastic body. A transfer sheet material formed of a non-stretchable resin film provided by laminating on the cylinder base, a shaft provided in a center hole provided at both ends of the cylinder base, the conductive elastic body, and the transfer sheet material. And a pair of disc members passing therethrough, wherein both end portions in the axial direction of the transfer sheet material are formed longer than both end portions in the axial direction of the cylinder base and the conductive elastic body, Both ends in the axial direction of the transfer sheet material are fixed on the circumferential surface of the disk member having a diameter slightly smaller than the inner diameter by being tightened from the outside in the radial direction by an annular member, and the transfer sheet material is fixed by the annular member. It is characterized in that it is held in a cylindrical shape while keeping a state of being pulled outward.
[0008]
According to the color image forming apparatus having such a configuration, since the transfer sheet material formed of the non-stretchable resin film is provided concentrically laminated outside the sponge-shaped conductive elastic body, the transfer sheet material is provided. Since the non-stretchable resin film has finer surface roughness than rubber, it is more excellent in transferability than rubber, and hardly causes dropout or transfer scattering during transfer. Further, since the transfer sheet material is not deformed by temperature or heat unlike rubber, the size of the transfer sheet material is easily controlled, and color shift and the like hardly occur.
[0009]
Further, in the present invention, the intermediate transfer body is not a seamless belt type that is stretched over a plurality of rollers, but a cylinder type is used. Therefore, it is possible to prevent a color shift or the like without increasing the assembly accuracy so much. Therefore, an inexpensive color image forming apparatus can be provided.
[0010]
Furthermore, as in the case of a seamless belt-type intermediate transfer member stretched over a plurality of rollers, abrasion causes slippage between the rollers and color misregistration, thereby lowering image quality and deteriorating durability. Therefore, a color image forming apparatus having excellent durability can be provided.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIGS. 1 to 5 are views referred to for explaining a color image forming apparatus according to a first embodiment of the present invention.
[0012]
In the color image forming apparatus shown in FIG. 1, an electrostatic latent image is formed on the photosensitive surface (circumferential surface) of the photoconductor 6 by the laser light R emitted from the laser light unit 9. The developing devices 15 to 18 develop, for example, magenta (red), yellow (yellow), cyan (blue), and black (black) color toners. It is designed to be multiply transcribed on the surface.
[0013]
The intermediate transfer body 1 on which the color toner image has been multi-transferred onto the circumferential surface from the photoreceptor 6 is transferred to a transfer paper (transfer sheet material) 10 which is sandwiched between a transfer roller device 7 and the multi-color toner image. Is secondary-transferred. The transfer paper 10 on which the color toner image has been secondarily transferred passes through the transfer roller device 7, where the charge is erased, separated from the intermediate transfer body 1, and sent to the fixing device 20 to fix the color toner image.
[0014]
The cross-sectional structure of the intermediate transfer body 1 as shown in FIG. 2 has a cylindrical aluminum base 2 made of aluminum and conductive on the innermost side as shown in FIG. A sponge-like conductive elastic body 3 having conductivity is provided concentrically laminated outside the conductive elastic body 3, and a seamless, non-stretchable resin film is provided outside the conductive elastic body 3. The formed transfer sheet materials 4 are provided so as to be concentrically stacked.
[0015]
The cylinder base 2 may be formed of a rigid body such as an iron-based material or a conductive resin, instead of aluminum.
As a material of the transfer sheet material 4, for example, polyetheretherketone (PEEK), polycarbonate, fluororesin, or the like can be used. Further, in order to form the transfer sheet material 4 seamlessly, the transfer sheet material 4 can be formed seamlessly by molding it into a drum shape by an extrusion molding method.
[0016]
The conductive elastic body 3 is elastically deformed by contact with the photoreceptor 6 and is used to secure an amount of nip (amount of contact) therebetween, and has a volume resistivity of 10 ⁸ Ω · cm or less. It is preferable to use This is because if the volume resistivity is larger than 10 ⁸ Ω · cm, transfer cannot be performed at a transfer voltage that is normally used.
[0017]
In particular, the volume resistivity of the conductive elastic body 3 is preferably in the range of 10 ⁶ to 10 ⁷ Ω · cm. If the volume resistivity is higher than 10 ⁷ Ω · cm, it is difficult to obtain a uniform resistance value over the entire surface. If it is not stable, and if it is lower than 10 ⁶ Ω · cm, the resistance value differs between the surface on which the toner is mounted and the surface on which the toner is not mounted, and the current tends to partially concentrate, thereby deteriorating the transfer sheet material 4.
[0018]
The hardness of the conductive elastic body 3 is preferably F95 degrees or less, and in the present embodiment, the hardness of the conductive elastic body 3 is F50 degrees. This is because if the hardness of the conductive elastic body 3 is larger than F95 degrees and is too hard, hollowing out occurs.
[0019]
In the present embodiment, the conductive elastic body 3 is formed into a cylindrical shape by bonding both ends of a sheet-shaped material. However, the conductive elastic body 3 is formed into a cylindrical shape from the beginning even if both ends are not bonded. ) May be used.
[0020]
As the volume resistivity of the transfer sheet material 4, a material having an area of 10 ⁸ to 10 ¹³ Ω · cm is used. This is because if the volume resistivity is smaller than 10 ⁸ Ω · cm, the surface electric field density of the transfer sheet material 4 increases and reverse transfer (transfer from the intermediate transfer body 1 to the photoreceptor 6) increases, resulting in 10 ¹³ Ω. When the size is larger than cm, the secondary transfer efficiency decreases and the separation of the transfer paper 10 from the intermediate transfer body 1 deteriorates. Particularly, the volume resistivity of the transfer sheet material 4 is preferably in a range of 10 ¹⁰ to 10 ¹² Ω · cm.
[0021]
As shown in FIG. 4, both ends of the transfer sheet material 4 in the axial direction are formed longer than both ends of the cylinder base 2 and the conductive elastic body 3 in the axial direction. Both ends of the length are radiused by a ring-shaped annular member 14 such as a barrel tag on a circumferential surface 12a of a disk member 12 having a circumferential surface 12a having a diameter slightly smaller than the inner diameter of the transfer sheet material 4. It is to be tightened and fixed from the outside in the direction.
[0022]
By fixing both ends of the transfer sheet material 4 in the axial direction to the circumferential surface 12a of the disk member 12 in this manner, the transfer sheet material 4 is pulled outward even if the conductive elastic body 3 is soft. It can be held in a cylindrical shape while keeping it.
[0023]
FIG. 5 is an exploded perspective view of the intermediate transfer body 1 before both ends of the intermediate transfer body 1 in the axial direction are fixed to the pair of disc members 12 and assembled as shown in FIG. 4 and 5, the shaft 11 is inserted into the center hole of the disk member 12 to form the rotation shaft of the intermediate transfer body 1.
[0024]
According to the color image forming apparatus having such a configuration, since the surface roughness of the transfer sheet material 4 is finer than rubber, the transfer sheet material 4 is more excellent in transferability than rubber, and it is unlikely to cause dropout or transfer scattering during transfer. Further, the transfer sheet material 4 is not deformed by temperature or heat unlike rubber, so that the dimensional control is easy and color shift and the like hardly occur.
[0025]
Further, in the present embodiment, since the intermediate transfer body 1 is not a belt-shaped one but a cylinder-shaped one, the color shift can be prevented without increasing the assembling accuracy of the apparatus. A color image forming apparatus can be provided.
[0026]
Further, as in the case of the intermediate transfer member of the seamless belt type according to the second conventional example, slippage occurs due to abrasion between the belt and the roller, which may cause deterioration in image quality and deterioration in durability due to color misregistration. Therefore, a color image forming apparatus having excellent durability can be provided.
[0027]
Further, the rotation speed can be kept constant by utilizing the inertia of the cylinder base 2, and the color shift of the image due to the rotation fluctuation can be minimized. In addition, the use of the seamless transfer sheet material 4 eliminates the need for a retracting mechanism or a fixing mechanism at the joints at both ends of the transfer sheet material, such as when the sheet-like transfer sheet material is wound around the conductive elastic body 3. As a result, the color image forming apparatus can be manufactured at low cost.
[0028]
Further, by adopting the intermediate transfer method using the intermediate transfer body 1, the sheet is not limited to a thin sheet as in the method of forming a color image by directly wrapping the sheet around the drum. As in the monochrome image forming apparatus that does not wind the paper, the range of selection of the sheet thickness is widened.
[0029]
FIG. 6 is a view showing an intermediate transfer member 1 according to a second embodiment of the color image forming apparatus according to the present invention. In the first embodiment, both ends in the axial direction of the intermediate transfer body 1 are fixed to the circumferential surface 12a of the disk member 12 by the annular member 14, whereas the second embodiment is different from the second embodiment. In the first embodiment, both ends in the axial direction of the transfer sheet material 4 of the intermediate transfer body 1 are annularly arranged and embedded in the circumferential surface 12a of the disk member 12, and the foam 22 imparts an expanding force to the outside of the radius. Is different in that it is fixed from the radial inside by its expanding force.
[0030]
In the first and second embodiments, both ends in the axial direction of the transfer sheet material 4 of the intermediate transfer body 1 are formed on the circumferential surface 12 a of the disk member 12 by the annular member 14 and the foam 22. Although the transfer sheet material 4 is fixed, both ends in the axial direction of the transfer sheet material 4 may be fixed with screw members such as screws, or the transfer sheet material 4 may be fixed by using both the annular member 14 and the screw member. You may make it fix both ends.
[0031]
【The invention's effect】
As described above, according to the color image forming apparatus of the present invention, there is provided a color image forming apparatus which forms a high quality image by preventing so-called hollow holes and color misregistration and is inexpensive and excellent in durability. can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram illustrating a color image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view of an intermediate transfer member 1 in FIG.
FIG. 3 is a sectional view taken along line III-III of the intermediate transfer body 1 in FIG.
FIG. 4 is a cross-sectional view of one of both end portions in the axial direction of the intermediate transfer body 1 in FIG.
FIG. 5 is an exploded perspective view of the intermediate transfer member 1 before final assembly.
FIG. 6 is a cross-sectional view of an intermediate transfer member 1 according to a second embodiment of the color image forming apparatus according to the present invention at one of both ends in the axial direction thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Intermediate transfer body 2 Cylinder base 3 Conductive elastic body 4 Transfer sheet material 6 Photoconductor 7 Transfer roller device 9 Laser light unit 10 Transfer paper 11 Shaft 12 Disk member 12a Circumferential surface 14 Ring member 15-18 Developing device 20 Fixing device 22 foam

Claims (3)

A photoreceptor for forming an electrostatic latent image;
A developing device that develops an electrostatic latent image of the photoconductor to form a toner image;
An intermediate transfer member that performs multiple transfer of a plurality of color toner images from the photoconductor,
A color image forming apparatus having a transfer device for secondary-transferring the multiple-transferred toner image to a transfer sheet material,
The intermediate transfer member,
A cylindrical base body formed in a cylindrical shape and having conductivity,
A sponge-like conductive elastic body provided concentrically laminated outside the cylinder base,
A transfer sheet material formed of a non-stretchable resin film that is provided concentrically laminated outside the conductive elastic body,
The cylinder base, the conductive elastic body and a pair of disk members provided at both end portions of the transfer sheet material, a shaft is inserted through a center hole,
Both ends in the axial direction of the transfer sheet material are formed longer than both ends in the axial direction of the cylinder base and the conductive elastic body,
Both ends of the transfer sheet material in the axial direction are fixed to the circumferential surface of the disk member having a diameter slightly smaller than the inner diameter by being tightened by a ring member from the outside in the radial direction, and the transfer sheet material is fixed to the ring member. color image forming apparatus is characterized in that so as to be held in a cylindrical shape while keeping the state of being pulled outwardly by. A photoreceptor for forming an electrostatic latent image;
A developing device that develops an electrostatic latent image of the photoconductor to form a toner image;
An intermediate transfer member that performs multiple transfer of a plurality of color toner images from the photoconductor,
A color image forming apparatus having a transfer device for secondary-transferring the multiple-transferred toner image to a transfer sheet material,
The intermediate transfer member,
A cylindrical base body formed in a cylindrical shape and having conductivity,
A sponge-like conductive elastic body provided concentrically laminated outside the cylinder base,
A transfer sheet material formed of a non-stretchable resin film that is provided concentrically laminated outside the conductive elastic body,
The cylinder base, the conductive elastic body and a pair of disk members provided at both ends of the transfer sheet material, the shaft is inserted through a central hole,
Both ends in the axial direction of the transfer sheet material are formed longer than both ends in the axial direction of the cylinder base and the conductive elastic body,
A foam that has an axial length at both ends in the axial direction of the transfer sheet material and is provided on the circumferential surface of the disk member having a diameter slightly smaller than the inner diameter, and is arranged in an annular shape around the circumference to apply an expanding force to the outside of the radius. A color image forming apparatus which is fixed from the radially inner side by its expanding force, and is held in a cylindrical shape while keeping a state in which the transfer sheet material is pulled outward by the foam. . A photoreceptor for forming an electrostatic latent image;
A developing device that develops an electrostatic latent image of the photoconductor to form a toner image;
An intermediate transfer member that performs multiple transfer of a plurality of color toner images from the photoconductor,
A color image forming apparatus having a transfer device for secondary-transferring the multiple-transferred toner image to a transfer sheet material,
The intermediate transfer member,
A cylindrical base body formed in a cylindrical shape and having conductivity,
A sponge-like conductive elastic body provided concentrically laminated outside the cylinder base,
A transfer sheet material formed of a non-stretchable resin film that is provided concentrically laminated outside the conductive elastic body,
The cylinder base, the conductive elastic body and a pair of disk members provided at both end portions of the transfer sheet material, a shaft is inserted through a center hole,
Both ends in the axial direction of the transfer sheet material are formed longer than both ends in the axial direction of the cylinder base and the conductive elastic body,
Both ends in the axial direction of the transfer sheet material were fixed on the circumferential surface of the disk member having a diameter slightly smaller than the inner diameter by a screw member, and the transfer sheet material was pulled outward by the screw member . A color image forming apparatus characterized in that the state is maintained in a cylindrical shape while keeping the state.

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