JP4088044B2 - Color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus such as a printer, a facsimile machine, and a copying machine capable of forming a color image using electrophotographic technology. In particular, the present invention relates to improvements in the drive mechanism of the image carrier and intermediate transfer member.
[0002]
[Prior art]
In general, an image forming apparatus using an electrophotographic technique includes a photosensitive member as an image bearing member having a photosensitive layer on an outer peripheral surface, a charging unit that uniformly charges the outer peripheral surface of the photosensitive member, and a charging unit. Exposure means for selectively exposing the outer peripheral surface charged in this manner to form an electrostatic latent image, and adding a toner as a developer to the electrostatic latent image formed by the exposure means to form a visible image The image forming apparatus includes developing means for forming a (toner image) and transfer means for transferring the toner image developed by the developing means onto a recording material such as paper to be transferred.
In the apparatus for forming a color image, as a transfer unit, a plurality of color toner images formed on the photosensitive member are sequentially primary transferred and superimposed, and the toner image formed as a color image is further transferred. An intermediate transfer body for secondary transfer onto a recording material such as a target sheet is provided. Alternatively, there is a rotating body that sequentially transfers a plurality of color toner images to the recording material while holding the recording material, and such a rotating body is also included in the intermediate transfer body. .
In such a color image forming apparatus, if the rotation of the image carrier (photosensitive member) and the intermediate transfer member is not stable, a plurality of color toners on the intermediate transfer member (or the recording material held on the intermediate transfer member) As a result, the accuracy of image superimposition is reduced, leading to a reduction in image quality.
[0003]
In view of this, a color image forming apparatus described in Japanese Patent Application Laid-Open No. 2000-147853 has already been proposed for the purpose of stabilizing the rotation of the image carrier and the intermediate transfer member.
FIG. 4 shows a drive mechanism in the color image forming apparatus.
This driving mechanism rotationally drives a driving pulley 3 of an intermediate transfer member (not shown, but arranged on the left side in FIG. 4) via a belt 2 by a motor 1. 3a is a drive shaft of the intermediate transfer member. A small pulley 3 b is integrally provided on the pulley 3, and the drive gear 7 of the image carrier is further rotationally driven through the small pulley 3 b, the belt 4, the pulley 5, and the gear 6. ing. Reference numeral 7a denotes a drive shaft of an image carrier (not shown, but arranged on the left side of FIG. 4).
In order to stabilize the rotation of the image carrier and the intermediate transfer member, a fly hole 3c is provided on the drive shaft 3a of the intermediate transfer member, and a flywheel 7c is provided on the drive shaft 7a of the image carrier.
[0004]
[Problems to be solved by the invention]
Flyholes are large because they cannot play their role unless they are heavy.
In the drive mechanism in the conventional color image forming apparatus shown in FIG. 4, heavy and large flywheels 3c and 7c must be provided on the drive shaft 3a of the intermediate transfer member and the drive shaft 7a of the image carrier, respectively. There is a problem that the whole apparatus becomes heavy and becomes large.
[0005]
An object of the present invention is to solve the above-described problems and provide a light-weight and small color image forming apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a color image forming apparatus according to claim 1, wherein an image carrier and an image formed on the surface of the image carrier are primarily transferred, and the image is further transferred to a recording material to be transferred. In an apparatus provided with an intermediate transfer member for secondary transfer, and a drive mechanism having a motor for rotationally driving these image carrier and intermediate transfer member,
An intermediate transfer member having a smaller number of teeth than the number of teeth of the image carrier driving gear fixed coaxially with the image carrier, and the image carrier driving gear fixed coaxially with the driving roller of the intermediate transfer member. A drive gear, and a drive gear fixed to the output shaft of the motor;
The image carrier driving gear and the intermediate transfer body driving gear are directly meshed with each other, and the intermediate transfer body driving gear and the driving gear are directly meshed with each other and coaxially with the intermediate transfer body driving gear. Only characterized by the provision of a flywheel .
[0007]
[Function and effect]
2. The color image forming apparatus according to claim 1, wherein the image carrier and the image formed on the surface of the image carrier are primarily transferred, and the image is further transferred to a recording material to be transferred. And a drive mechanism having a motor that rotationally drives the image carrier and the intermediate transfer member.
An intermediate transfer member having a smaller number of teeth than the number of teeth of the image carrier driving gear fixed coaxially with the image carrier, and the image carrier driving gear fixed coaxially with the driving roller of the intermediate transfer member. A drive gear, and a drive gear fixed to the output shaft of the motor;
The image carrier driving gear and the intermediate transfer body driving gear are directly meshed with each other, and the intermediate transfer body driving gear and the driving gear are directly meshed with each other and coaxially with the intermediate transfer body driving gear. Since only the flywheel is provided , this apparatus eliminates the need to provide a flywheel for the drive shaft of the image carrier and the drive shaft of the intermediate transfer member, and is coaxial with the intermediate transfer member drive gear. It would be enough to have one flywheel on top.
Therefore, according to the color image forming apparatus of the first aspect, the weight and size can be reduced .
Further, the number of teeth of the intermediate transfer body driving gear, since Tsu less kuna than the number of teeth of said image bearing member driving gear, an intermediate transfer member drive gear and the flywheel are compared with the image bearing member driving gearing Will rotate at high speed.
As the rotational speed of the flywheel increases, the higher the stability, the higher the rotational stability compared to the case where the flywheel is provided directly on the drive shaft of the image carrier and the drive shaft of the intermediate transfer member. Will be obtained.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a reference example partially provided with a configuration that is a premise of the embodiment of the present invention will be described.
<First Reference Example >
FIG. 1 is a schematic front view showing the main part of the first reference example .
[0009]
This image forming apparatus is an apparatus capable of forming a full-color image. The image carrier 10 and an image formed on the surface of the image carrier 10 are primarily transferred (T1), and this image is further transferred. An intermediate transfer member 20 that performs secondary transfer (T2) to the recording material S, and a drive mechanism 30 having a motor 31 that rotationally drives the image carrier 10 and the intermediate transfer member 20.
[0010]
The image carrier 10 is composed of a photosensitive member having a photosensitive layer on its outer peripheral surface, and around the photosensitive member 10, the outer peripheral surface of the photosensitive member 10 is aligned along the rotation direction (the arrow direction in the drawing). Charging means 11 for charging in this manner, and exposure means (not shown) for selectively exposing the outer peripheral surface of the photoreceptor 10 uniformly charged by the charging means 11 to form an electrostatic latent image. The electrostatic latent image formed by the exposure unit is applied with a toner as a developer to form a visible image (toner image), the intermediate transfer body 20, and the photosensitive material after the primary transfer (T1). A cleaning means 13 for removing toner remaining on the surface of the body 10 is disposed.
An image carrier driving gear 14 for driving the image carrier 10 is coaxially fixed to the end of the image carrier 10.
[0011]
The developing means 12 is a rotary developing unit, and a developing roller 12Y for yellow, a developing roller 12C for cyan, a developing roller 12M for magenta, and a developing roller 12K for black with respect to a main body 12a which is a rotating body. And the main body 12a is rotated at a 90 ° pitch in the direction of the arrow, whereby the surface of the photoconductor 10 can be selectively developed.
[0012]
The intermediate transfer member 20 is constituted by an intermediate transfer belt on which a toner image formed on the photoreceptor 10 is subjected to primary transfer T1, and this toner image is further subjected to secondary transfer T2 to a recording material S to be transferred.
The intermediate transfer belt 20 is stretched around a drive roller 21, a guide roller 22, a tension roller 23, and a secondary transfer backup roller 24, and is driven to rotate (circulate) in the direction of the arrow shown in the drawing. The primary transfer portion T 1 is formed between the driving roller 21 and the guide roller 22, and the secondary transfer portion T 2 is formed at the pressure contact portion between the secondary transfer backup roller 24 and the secondary transfer roller 25.
The secondary transfer roller 25 can be brought into contact with and separated from the secondary transfer backup roller 24 (and therefore with respect to the intermediate transfer belt 20), and a secondary transfer portion T2 is formed when contacted.
Therefore, when forming a color image, a toner image of a plurality of colors is superimposed on the intermediate transfer belt 20 with the secondary transfer roller 25 being separated from the intermediate transfer belt 20, and then a color image is formed. The secondary transfer roller 25 contacts the intermediate transfer belt 20, and the sheet S is supplied to the contact portion (secondary transfer portion T2), whereby the image is transferred onto the sheet.
A cleaning unit 26 is capable of coming into contact with and separating from the intermediate transfer belt 20 and removes toner remaining on the intermediate transfer belt 20 after the secondary transfer.
An intermediate transfer member drive 27 for driving this, that is, for driving the intermediate transfer member 20, is fixed to the end of the drive roller 21 on the same axis.
[0013]
The driving mechanism 30 branches and transmits the power from the motor 31 to an image carrier driving gear 14 for driving the image carrier 10 and an intermediate transfer body driving gear 27 for driving the intermediate transfer body 20. A common branch gear 32 and a flywheel 33 provided coaxially with the branch gear 32 are provided.
[0014]
A drive gear 31a is fixed to the output shaft of the motor 31. The drive gear 31a and the branch gear 32 mesh with each other, whereby the branch gear 32 is rotationally driven, and the branch gear 32 and the image carrier are driven. The image carrier 10 is rotationally driven by meshing with the gear 14.
Further, the branch gear 32 is integrally provided with a small-diameter gear 32a, and a timing belt 34 is stretched between the gear 32a and the intermediate transfer body drive gear 27, thereby driving the intermediate transfer body. The gear 27 (and hence the intermediate transfer member 20) is driven to rotate.
As can be seen from the above, the branch gear 32 is the final stage power transmission gear with respect to the image carrier driving gear 14 and the intermediate transfer body driving gear 27.
Further, the branch gear 32 is configured by a gear whose number of teeth is smaller than that of the image carrier driving gear 14 and smaller than that of the intermediate transfer body driving gear 27.
[0015]
According to the color image forming apparatus as described above, the following operational effects can be obtained.
(A) The image carrier 10 and an intermediate transfer member 20 that performs a primary transfer T1 on the image formed on the surface of the image carrier 10, and further performs a secondary transfer T2 on the recording material S to be transferred; A drive mechanism 30 having a motor 31 that rotationally drives the image carrier 10 and the intermediate transfer member 20 is provided. The power from the motor 31 is intermediate between the image carrier drive gear 14 for driving the image carrier 10 and the intermediate. Since a common branch gear 32 that branches and transmits to the intermediate transfer body drive gear 27 for driving the transfer body 20 is provided, and a flywheel 33 is provided coaxially with the branch gear 32. It is not necessary to provide a flywheel for each of the image carrier 10 and the intermediate transfer member 20, and it is sufficient to provide one flywheel 33 coaxially with the branch gear 32.
Therefore, according to this color image forming apparatus, it is possible to reduce the weight and size.
(B) Since the branch gear 32 is the final stage power transmission gear with respect to the image carrier drive gear 14 and the intermediate transfer member drive gear 27, the branch gear 32, the image carrier drive gear 14, and the intermediate transfer gear. Drive unevenness does not occur with the body drive gear 27.
Therefore, the rotation stabilizing action by the flywheel 33 is reliably transmitted to the image carrier drive gear 14 and the intermediate transfer member drive gear 27, and as a result, the rotation of the image carrier 10 and the intermediate transfer member 20 is reliably stabilized. .
(C) Since the number of teeth of the branch gear 32 is smaller than the number of teeth of the image carrier driving gear 14 and smaller than the number of teeth of the intermediate transfer body driving gear 27, the branch gear 32 and the flywheel 33 are The image carrier driving gear 14 and the intermediate transfer member driving gear 27 rotate at a higher speed.
As the rotational speed of the flywheel increases, a higher stability can be obtained. Therefore, higher rotational stability can be obtained compared to the case where flywheels are provided directly on the image carrier 10 and the intermediate transfer body 20, respectively. Become.
[0016]
<Second Reference Example >
FIG. 2 is a schematic front view showing a main part of the second reference example . In the figure, the same or corresponding parts as those in the first reference example are denoted by the same reference numerals.
This reference example is different from the first reference example in that the intermediate transfer member drive gear 27 (and hence the intermediate transfer member 20) is driven to rotate by the meshing of the branch gear 32 and the intermediate transfer member drive gear 27. The timing belt 35 is stretched between the small-diameter gear 32a of the branch gear 32 and the image carrier driving gear 14, so that the image carrier driving gear 14 (and hence the image carrier 10) is driven to rotate. There is no change in other points.
Same effect as the first reference example can be obtained by such a reference example.
[0017]
Next, an embodiment of the present invention will be described.
Figure 3 is a schematic front view showing an essential part of the implementation in the form of a color image forming apparatus according to the present invention. In the figure, the same or corresponding parts as those in the first reference example are denoted by the same reference numerals.
Is different from this embodiment is the first reference example, the branch gear 32 and the intermediate transfer body driving gear 27 constituted by a gear of a common (shared), the gear 31a and the middle between the transfer member drive gear of the motor 31 The intermediate transfer body drive gear 27 (and therefore the intermediate transfer body 20) is rotationally driven by meshing with the 27 (branch gear 32), and the branch gear 32 (intermediate transfer body drive gear 27), the image carrier drive gear 14, and the like. , The image carrier driving gear 14 (and hence the image carrier 10) is configured to be rotationally driven.
The intermediate transfer member 20 is stretched by a driving roller 21, a secondary transfer backup roller 24, and a driven roller 28.
That is, in this embodiment, the image carrier 10 and the intermediate transfer member 20 on which the image formed on the surface of the image carrier 10 is primarily transferred, and this image is further transferred to a recording material to be transferred. And a drive mechanism 30 having a motor 31 that rotationally drives the image carrier 10 and the intermediate transfer member 20,
The number of teeth less than the number of teeth of the image carrier driving gear 14 fixed coaxially with the image carrier 10 and the image carrier driving gear 14 fixed coaxially with the driving roller 21 of the intermediate transfer member 20. A number of intermediate transfer member drive gears 27, and a drive gear 31a fixed to the output shaft of the motor 31,
The image carrier driving gear 14 and the intermediate transfer member driving gear 27 directly mesh with each other, and the intermediate transfer member driving gear 27 and the driving gear 31a directly mesh with each other, and the intermediate transfer member driving gear. 27, the flywheel 33 is provided only on the same axis.
Also according to such an embodiment, the same effect as the first reference example can be obtained.
Further, since the branch gear 32 and the intermediate transfer member drive gear 27 are constituted by a common (shared) gear, and the flywheel 33 is provided coaxially with this gear, the intermediate transfer member drive gear 27 (that is, the intermediate transfer member drive gear 27). The transfer body 20) is rotated stably by the direct action of the flywheel 33, and the number of teeth of the branch gear 32 (intermediate transfer body drive gear 27) is smaller than the number of teeth of the image carrier drive gear 14. Therefore, high rotational stability can be obtained for the image carrier 10 as well.
[0018]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the gist of the present invention.
[0019]
【The invention's effect】
By the color image forming apparatus according to claim 1 Symbol mounting lever, it is possible to reduce the weight and size.
Further , the rotation of the image carrier and the intermediate transfer member is reliably stabilized .
[0020]
[Brief description of the drawings]
1 is a schematic front view showing an essential part of the first reference example.
2 is a schematic front view showing an essential part of the second reference example.
Schematic front view showing an essential part of the implementation in the form of a color image forming apparatus according to the present invention; FIG.
FIG. 4 is an explanatory diagram of a conventional technique.
[Explanation of symbols]
10 Photoconductor (image carrier)
14 Image carrier drive gear 20 Intermediate transfer belt (intermediate transfer member)
27 Intermediate transfer member drive gear 30 Drive mechanism 31 Motor 32 Branch gear 33 Flywheel

Claims (1)

An image carrier, an intermediate transfer member on which the image formed on the surface of the image carrier is primarily transferred, and the image is further transferred to a recording material to be transferred, and the image carrier and the intermediate transfer member. In an apparatus provided with a drive mechanism having a motor for rotational driving,
An intermediate transfer member having a smaller number of teeth than the number of teeth of the image carrier driving gear fixed coaxially with the image carrier and the image carrier driving gear fixed coaxially with the driving roller of the intermediate transfer member. A drive gear, and a drive gear fixed to the output shaft of the motor;
The image carrier driving gear and the intermediate transfer member driving gear directly mesh with each other, and the intermediate transfer member driving gear and the driving gear directly mesh with each other, and are coaxial with the intermediate transfer member driving gear. A color image forming apparatus provided with only a flywheel .

Images