JP3457152B2 - Image forming device - Google Patents

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 such as a copying machine or a printer, and more particularly to an intermediate transfer drum or a photosensitive drum used in the image forming apparatus.

[0002]

2. Description of the Related Art In conventional image forming apparatuses such as copying machines and printers, especially color copying machines and color printers, for example, a primary toner image formed on a photoconductor is primarily transferred onto an intermediate transfer body. 1 on this intermediate transfer member
There is an intermediate transfer method in which a secondary toner image formed by secondary transfer is secondary transferred to a transfer sheet material such as transfer paper, and various types of intermediate transfer members have been proposed. ,It has been implemented.

Conventionally, there are roughly two types of intermediate transfer members: a system using an endless (seamless) conductive transfer belt and a system using a cylindrical transfer drum. The main ones of conventional intermediate transfer members are shown below, and they will be briefly described.

FIG. 7 is a diagram showing an image forming apparatus of a system using an endless electroconductive transfer belt. The image forming apparatus shown in the figure has a structure in which an endless conductive transfer belt 50 as an intermediate transfer member is stretched around a plurality of (three) backup rollers 53.

In FIG. 7, reference numeral 54 is a photosensitive member, 5
6 is a transfer paper, and 58 is a fixing device. The image forming apparatus using such an endless transfer belt 50 has an advantage that the apparatus can be downsized, but the transfer belt 50 is easily misaligned or wrinkled. There is a large possibility of being disturbed, or there is a problem that the assembly is very difficult in order to prevent the occurrence of shifts and wrinkles.

FIG. 8 is a diagram showing a system using a cylindrical transfer drum as an intermediate transfer member. As shown in the figure,
The transfer drum 60 as an intermediate transfer member is formed on the drum base 61 formed of aluminum, rubber, or the like.
A transfer film 62 forming a cylindrical peripheral surface is attached, and a tension coil spring 64 is provided between both ends 62a, 62a of the transfer film 62 to apply tension to the transfer film 62 to prevent the occurrence of deviations and wrinkles. The transfer film 62 can be prevented and the dimensional change due to the temperature change can be absorbed.

[0007]

However, in the conventional transfer drum 60 as shown in FIG. 8 described above, the tension coil spring 64 extending in the circumferential direction is provided in a part of the circumference to increase the diameter. Inevitably, there is a problem that the device becomes large.

In order to solve this problem, as shown in FIG. 9, one of both end portions 62a, 62a of the transfer film 62 is provided with one of the recesses 67 formed in a part of the transfer drum 66 in the circumferential direction. It is conceivable that the transfer film 62 is attached to the rising surface 67a (on the left side in the drawing) and the other end 62a of the transfer film 62 is pressed against the bottom surface 67b of the recess 67 by the pressing spring 68. By doing so, the circumferential length of the transfer drum 66 can be made small, that is, the diameter can be made small, so that the enlargement of the apparatus can be prevented.

However, in the transfer drum 66 shown in FIG. 9, the end portion 62a of the transfer film 62 on the side to which the pressing force is applied by the pressing spring 68 is bent at a substantially right angle by the corner portion 66a of the transfer drum 66. Therefore, in order to generate tension in the circumferential direction of the transfer film 62, the pressing force of the transfer drum 66 in the radial direction is applied by the pressing spring 68.
When added to a, the transfer film 6 is formed by the corner portion 66a.
Since the tension in the circumferential direction of 2 is reduced, if the pressing force is increased in order to generate the tension, the transfer film 62 in the corner portion 66a may be damaged due to an excessive force. .

In view of the above problems, the present invention provides an image forming apparatus capable of preventing an increase in size of the apparatus and preventing local damage of a film member forming a cylindrical peripheral surface of an intermediate transfer drum. Is an issue.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a photoconductor which develops an electrostatic latent image by exposure to form a primary toner image, and the photoconductor to the primary toner image. An intermediate transfer drum that has a cylindrical peripheral surface that forms a secondary toner image by being primarily transferred onto the transfer sheet material, and an intermediate transfer drum that transfers the secondary toner image to a transfer sheet material. intermediate transfer drum, and a film member forming the cylindrical peripheral surface is adhered to the outermost layer, before
A cylindrical elastic body is formed inside the film member in the radial direction.
Elastic layer, and a member accommodating portion whose cross section is formed in a U shape recessed from a part of the cylindrical peripheral surface in the circumferential direction and which has two rising surfaces and extends in the axial direction. A shaft member that is housed so as to be retracted inward from the leading end of the rising surface of the member housing part and has both ends rotatably supported; and a shaft member that is connected to both ends of the shaft member to rotate the shaft member. And a rotational urging means for urging, wherein one end of the film member in the circumferential direction is attached to one of the two rising surfaces of the member storage portion, and the other end is attached to the shaft member. By rotating the shaft member, the other end of the film member is pulled in the tangential direction of the intermediate transfer drum.

According to the image forming apparatus having such a configuration,
By rotationally biasing the shaft member housed in the member housing portion by the rotating biasing means, the other end portion of the film member having one end stuck to one of the pair of rising surfaces of the member housing portion is the shaft member. The film member can be attached to the outermost surface layer portion of the intermediate transfer drum to form a cylindrical peripheral surface by pulling the film member in the tangential direction of the intermediate transfer drum by being rotated together with the shaft member. It is possible to reliably prevent the film member from being displaced or wrinkled.

Therefore, like the conventional transfer drum 60 (see FIG. 8), the tension coil spring 6 extending in the circumferential direction.
Even if the number 4 is not provided, it is possible to prevent the film member from being displaced or wrinkled, so that it is possible to prevent the diameter of the intermediate transfer drum from increasing and the apparatus from increasing in size.

Further, since the other end of the film member is wound around the arc surface by the rotation of the shaft member and pulled in the tangential direction of the cylindrical peripheral surface of the intermediate transfer drum, the conventional transfer drum 66 ( As shown in FIG. 9), no excessive force is applied by the corner portion 66a of the drum base 61, etc., so that the film member of the intermediate transfer drum can be prevented from being locally damaged.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 6
FIG. 1 is a diagram showing a color image forming apparatus and an intermediate transfer drum according to a first embodiment of an image forming apparatus according to the present invention.

FIG. 1 is a diagram showing a main part of a color image forming apparatus. In the figure, of the two photoconductors 6a and 6b, the photoconductor 6a on the left side of the diagram, for example, intermediately transfers a color image (primary toner image) formed by magenta (red) and black (black). Multiple transfer (1
Next, the photosensitive member 6b on the right side of the drawing is, for example, a color image (1) formed by yellow (yellow) and cyan (blue).
By secondary transfer (primary transfer) of the next toner image) onto the surface of the intermediate transfer drum 1, a secondary toner image is formed on the cylindrical peripheral surface of the intermediate transfer drum 1.

The intermediate transfer drum 1 on which a secondary toner image is formed by multiple-transferring a color image onto the surface from the two photoconductors 6a and 6b is a transfer sheet that is sandwiched between the transfer roller 7 and the transfer sheet. The multiple color images (secondary toner images) are secondarily transferred onto the (transfer sheet material) 10. After the transfer paper 10 on which the color image is secondarily transferred passes through the transfer roller 7, the separation device 8 removes the charge and separates it from the intermediate transfer drum 1, and the transfer device 12 sends it to the fixing device on the left side of the drawing. To be

The structure of the intermediate transfer drum 1 has a conductive cylinder 2 made of aluminum on the innermost diameter side, and a sponge-like conductive elastic body 3 having conductivity is provided outside the conductive cylinder 2. Are attached, and both ends of the conductive elastic body 3 in the circumferential direction are abutted and fixed to the outside of the locking member 16.

A sheet-shaped non-stretchable transfer film 4 (film member) is attached and provided on the outer side of the conductive elastic body 3, and one of both ends in the circumferential direction of the transfer film 4 is provided. The inside of the locking member 16 is bent and locked, and the other is wound around a shaft member and fixed with tension applied thereto as described later. As the material of the transfer film 4, for example, a high resistance material such as polyetheretherketone (PEEK material), polycarbonate, or fluororesin can be used.

By the way, the diameter of the intermediate transfer drum 1 is determined so as to have a circumferential length slightly longer than the length of the legal size paper. For example, the diameter of the intermediate transfer drum 1 is 11.
It is preferred within the scope of 8~140mm ^φ.

Next, the structure of the intermediate transfer drum 1 will be described in more detail. 2 is a perspective view of the intermediate transfer drum 1, and FIG. 3 is an exploded perspective view of the intermediate transfer drum 1. As shown in the figure, the intermediate transfer drum 1 includes a cylindrical conductive cylinder 2 made of aluminum, and a pair of circular shapes provided at both ends of the conductive cylinder 2 to close the openings at both ends. A locking member 1 provided along the length direction of the flange member 14 and the conductive cylinder 2 for locking both ends of the conductive elastic body 3 and the transfer film 4 in the circumferential direction.
6 and a shaft member 18 that is inserted into the shaft holes 14a of the pair of circular flange members 14 to support the intermediate transfer drum 1.
It has a sponge-like conductive elastic body 3 having conductivity and a sheet-like non-stretchable transfer film 4. The circular flange member 14 is made of a synthetic resin material such as POM (polyacetal).

As shown in FIG. 4, the locking member 16 has a substantially U-shaped cross section, and has a rising portion 16a on both sides and a bottom portion 1.
By 6b, a member housing portion 17 that is recessed from the cylindrical peripheral surface of the transfer film 4 is defined inside them.

As shown in FIG. 4, a shaft member 20 is housed in the member housing portion 17, and both ends of the shaft member 20 are circular at both ends of the intermediate transfer drum 1 as shown in FIG. It is inserted into the support hole 14b of the flange member 14 and is rotatably supported. As shown in FIG. 4, the shaft member 20 has a flat surface portion 20a formed by linearly forming a part of the circular shape in the cross section in the circumferential direction.

As shown in FIG. 3, a rotating lever 22 is connected to both ends of the shaft member 20 so as to extend in a perpendicular direction.
The turning lever 22 is arranged outside the circular flange member 14 as shown in FIGS.
One end of a tension coil spring (elastic tension means) 24 is connected to the tip of the rotating lever 22 opposite to the shaft member 20, and the other end of the tension coil spring 24 is provided on the circular flange member 14. It is locked to the locking pin 26.

The tension coil spring 24 is a circular flange member 14 at the end of the intermediate transfer drum 1 on the back side of the paper surface in FIG.
Also, they are provided in the same direction as in FIG. 5 and inclined by the same angle. The rotating lever 22 and the tension coil spring 24 are
A rotation urging unit that urges the shaft member 20 to rotate is configured.

As shown in FIG. 4, one end portion 4a in the circumferential direction of the transfer film 4 is fixed to the rising portion 16a on the left side of the locking member 16 in the drawing by an adhesive. The other end portion 4b in the circumferential direction of 4 is attached and fixed to the flat surface portion 20a of the shaft member 20 with an adhesive.

Therefore, as shown in FIG. 5, when the rotating lever 22 rotates counterclockwise in the figure by the tensile force of the tension coil spring 24, the shaft member 2 is rotated as shown in FIG.
0 rotates in the direction of the arrow, and the other end 4b of the transfer film 4 attached to the flat surface portion 20a of the shaft member 20 also rotates in the same direction.

As a result, the transfer film 4 is pulled in the tangential direction of the outer diameter of the intermediate transfer drum 1 while being wound around the arcuate portion of the shaft member 20.
As shown in FIG. 5, since a predetermined tensile force T can be applied in the circumferential direction of the transfer film 4, it is possible to prevent the transfer film 4 from being displaced or wrinkled.

In the above embodiment, the case where the present invention is applied to an intermediate transfer drum used in a color printer or the like has been described. However, the present invention applies to exposure and transfer paper used in a monochrome printer or the like. It can also be applied to a photosensitive drum in which the transfer is performed by one transfer body.

Further, in the above embodiment, the shaft member 2
The end portion of the transfer film 4 was adhered to the flat surface portion 20a formed in 0 with an adhesive, but the transfer film 4 was adhered to the cylindrical peripheral surface of the shaft member 20 without forming the flat surface portion 20a, or was adhered. The transfer film 4 may be fixed by a mechanical fixing means such as a screw instead of the agent.

Further, in the above embodiment, the shaft member 2
Although the rotation urging means for urging 0 to rotate is constituted by the rotating lever 22 and the tension coil spring 24, the rotation urging means may have any other structure as long as it can exhibit the same function. May be used.

Further, although the tension coil spring 24 is used as the elastic tensioning means in the above-described embodiment, another type of spring may be used as the elastic tensioning means, or a synthetic rubber may be used instead of the mechanical elastic body. Other elastic materials such as a body may be used.

[0033]

As described above, according to the present invention,
By rotationally biasing the shaft member housed in the member housing portion by the rotating biasing means, the other end portion of the film member having one end stuck to one of the pair of rising surfaces of the member housing portion is the shaft member. The film member can be attached to the outermost surface layer portion of the intermediate transfer drum to form a cylindrical peripheral surface by pulling the film member in the tangential direction of the intermediate transfer drum by being rotated together with the shaft member. It is possible to reliably prevent the film member from being displaced or wrinkled.

Therefore, the tension coil spring 6 extending in the circumferential direction like the conventional transfer drum 60 (see FIG. 8).
Even if the number 4 is not provided, it is possible to prevent the film member from being displaced or wrinkled, so that it is possible to prevent the diameter of the intermediate transfer drum from increasing and the apparatus from increasing in size. Therefore, the cost increase of the device can be prevented.

Further, since the other end of the film member is wound around the arc surface by the rotation of the shaft member and pulled in the tangential direction of the cylindrical peripheral surface of the intermediate transfer drum, the conventional transfer drum 66 ( As shown in FIG. 9), no excessive force is applied to the corner portion 66a or the like, so that the film member of the intermediate transfer drum can be prevented from being locally damaged.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a color image forming apparatus using an intermediate transfer drum 1 according to a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view of an intermediate transfer drum 1 in FIG.

FIG. 3 is an exploded perspective view of the intermediate transfer drum 1 in FIG.

FIG. 4 is a sectional view taken along line IV-IV of the intermediate transfer drum 1 in FIG.

5 is a view of the intermediate transfer drum 1 in FIG. 2 as viewed in the direction of arrow V. FIG.

6 is a sectional view of the intermediate transfer drum 1 in FIG. 2 taken along the line VI-VI.

FIG. 7 is a schematic configuration diagram showing an image forming apparatus using a conventional endless transfer belt 50.

FIG. 8 is a schematic configuration diagram showing a conventional transfer drum 60.

9 is a schematic configuration diagram showing a transfer drum 66 that can be considered from the transfer drum 60 shown in FIG.

[Explanation of symbols]

1 Intermediate transfer drum 2 Conductive cylinder 3 Conductive elastic body 4 Transfer film 4a One end 4b the other end 6a, 6b photoconductor 7 Transfer roller 8 Separation device 10 Transfer paper 12 Conveyor 14 Circular flange member 14a shaft hole 14b Support hole 16 Locking member 16a rising part 16b bottom 17 Component storage 18 Shaft member 20 shaft members 20a flat part 22 Rotating lever 24 tension coil spring 50 transfer belt 53 Backup roller 54 photoconductor 56 transfer paper 58 Fixing device 60 transfer drum 61 drum base 62 Transfer film 62a end 64 tension coil spring 66 transfer drum 67 recess 67a Rising surface 67b bottom 68 Pressing spring

Claims (4)

(57) [Claims] 1. A photoconductor that develops an electrostatic latent image by exposure to form a primary toner image, and a primary toner image is primarily transferred from the photoconductor to form a secondary toner image. An image forming apparatus having an intermediate transfer drum having a cylindrical peripheral surface and secondarily transferring the secondary toner image onto a transfer sheet material, wherein the intermediate transfer drum is attached to an outermost surface layer portion, and A film member forming a peripheral surface, an elastic layer in which an elastic body is formed in a cylindrical shape on the inner side in the radial direction of the film member, and a cross section recessed from a part of the cylindrical peripheral surface in the circumferential direction from the cylindrical peripheral surface A member housing portion formed in a U shape and having two rising surfaces and extending in the axial direction, and a member housing portion housed so as to be retracted inward from a tip of the rising surface of the member housing portion and rotatably supported at both ends. And a shaft member to be attached to both ends of the shaft member. And a rotation urging unit that urges the shaft member to rotate so as to rotate the shaft member. One end portion of the film member in the circumferential direction is attached to one of the two rising surfaces of the member storage portion, and the other. An image forming apparatus, wherein an end portion is attached to the shaft member, and the other end portion of the film member is pulled in a tangential direction of an intermediate transfer drum by rotating the shaft member. 2. The image forming apparatus according to claim 1, wherein a flat surface portion is formed by linearly forming a part of a circular shape in a cross section of the shaft member in a circumferential direction. 3. The rotating biasing means includes a pair of rotating levers, one end of each of which is fixed to both ends of the shaft member and the other end of which extends in a direction perpendicular to the shaft member; One end is connected to the other end, the other end is fixed to both ends of the intermediate transfer drum, and is arranged along the circumferential direction of the intermediate transfer drum to rotate the other end of the rotating lever. The image forming apparatus according to claim 1, further comprising a pair of elastic tensioning means for urging. 4. A circular flange for closing the end portion of the intermediate transfer drum is provided, the elastic tensioning means is housed in a concave portion formed concentrically on the flange, and one end portion of the elastic tensioning means is the 4. The image forming apparatus according to claim 3, wherein the image forming apparatus is connected to the other end of the rotating lever, and the other end of the elastic pulling means is fixed by a locking pin provided in the recess of the flange.