JPH06115151A - Recording device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a recording apparatus using an intermediate transfer drum, and recording capable of preventing the contact fluctuation between the photosensitive drum and the intermediate transfer drum to improve the printing quality and the life of the apparatus. Provide a device. An intermediate transfer drum in which an electrostatic latent image is formed on a surface of a charged photosensitive drum 10 by laser beam exposure, the electrostatic latent image is developed by each color developing device, and the developed toner image of each color is pressed against the photosensitive drum 10. In the color recording apparatus of the type that sequentially transfers the image to the shaft 20, the shaft 10a of the photosensitive drum 10
Is supported so as to be displaceable in the incident direction of the laser beam, whereby the contact pressure between the photosensitive drum 10 and the intermediate transfer drum 20 can be managed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color recording apparatus using an intermediate transfer drum.

[0002]

2. Description of the Related Art FIG. 8 is a side view showing an outline of the structure of a conventional color recording apparatus, and its structure and action are as follows. First, a recording sheet 1 is sent by a recording command from a control unit (not shown).
00 feeding operation is started. That is, the pick roller 2 provided in the feeding unit takes out the recording paper 100 from the paper cassette 1, conveys it to the nip portion of the registration roller 3, and puts it on standby.

Around the photosensitive drum 10, a charger 16,
An exposure system 50, YMCK color developing units 11 to 14, and a cleaner 15 are provided, and a toner image is formed on the photosensitive drum 10 in order of YMCK every rotation of the drum by a known electrophotographic process.

The photosensitive drum 10 includes an intermediate transfer drum 20.
Are opposed to each other. The intermediate transfer drum 20 rotates while contacting the photosensitive drum 10. Each YMCK toner image on the photosensitive drum 10 is transferred (primarily transferred) onto the intermediate transfer drum 20 each time it is formed. The residual toner on the surface of the photosensitive drum 10 after the transfer is completed is cleaned by the cleaner 15.

When the transfer of all four colors of YMCK onto the intermediate transfer drum 20 is completed, the registration roller 3 rotates and sends the recording paper 100 to the transfer roller 30. Here, the transfer roller 30 is pressed against the intermediate transfer drum 20 with the recording paper 100 interposed therebetween, and the color images are collectively transferred (secondary transfer) to the recording paper 100.

When the transfer onto the recording paper 100 is completed, the transfer roller 30 is separated from the intermediate transfer drum 20. The cleaner blade 25 cleans the intermediate transfer drum 20. After cleaning, the cleaner blade 25
Are separated from the intermediate transfer drum 20.

The recording paper 100 is finally sent to the fixing device 40, and the color toner image is fixed on the recording paper 100 by the heat and pressure of the fixing roller 41 and the pressure roller 42. By repeating the above operation, color recording is performed one after another.

[0008]

As described above, in order to transfer the toner image from the photosensitive drum to the intermediate transfer drum,
The photosensitive drum needs to rotate while contacting the intermediate transfer drum. At this time, a shake error may occur around the axis due to manufacturing problems of both drums, and in this case, large contact pressure fluctuations occur between the photosensitive drum and the intermediate transfer drum. Since this fluctuation in contact pressure causes deterioration of print quality and shortening of the life of the apparatus, it is necessary to release the contact pressure by some means.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color recording apparatus capable of preventing fluctuations in contact pressure between a photosensitive drum and an intermediate transfer drum and improving printing quality and life of the apparatus.

[0010]

In order to achieve the above object, in the present invention, an electrostatic latent image is formed on a surface of a charged photosensitive drum by laser beam exposure, and the electrostatic latent image is developed by each color developing device. In a color recording apparatus of a type that sequentially transfers the formed toner images of respective colors to an intermediate transfer drum that is in pressure contact with the photosensitive drum, a shaft of the photosensitive drum is supported so as to be displaceable in a laser beam incident direction. To do.

[0011]

Since the shaft of the photosensitive drum is movable in the incident direction of the laser beam, the fluctuation of the contact pressure between both drums due to the runout error around the shaft, which has been a problem in the past, can be released to the shaft of the photosensitive drum. Therefore, it is possible to prevent deterioration of printing quality and shortening of the life of the apparatus.

[0012]

Embodiments of the present invention will be described below with reference to FIGS.

1 to 4 show a first embodiment.

FIG. 1 is a side view showing an outline of the structure of a recording apparatus according to the first embodiment of the present invention. In the drawing, reference numeral 60 is a photosensitive drum shaft support structure. In addition, the same reference numerals are used for other members similar to those in the related art. The photosensitive drum shaft support structure 60 includes a linear guide 61 that supports the shaft 10a of the photosensitive drum 10,
A spring 62 for urging the linear guide 61 in the direction of arrow A to press the photosensitive drum 10 against the intermediate transfer drum 20.
It has and. The structure and operation of the photosensitive drum shaft support structure 60 will be described in detail with reference to FIG.

The linear guide 61, which supports the shaft 10a of the photosensitive drum through the hole 61a, is guided by the guide bar 63 and is movable in the direction of arrow B (the hole 61b of the linear guide 61).
Is fitted to the guide bar 63), the support portions 64 at both ends of the guide bar 63 are attached to the side frames 65 of the device.
It is fixed to. Reference numeral 65a is a positioning hole into which a part of the support portion 64 fits. The arrow B direction coincides with the incident direction of the laser beam from the exposure system 50. 66 is a support plate for the spring 62, the tip of which is the side frame 65.
Engaged with the hole 65b.

As described above, the shaft 10a of the photosensitive drum 10 is supported so as to be displaceable in the incident direction of the laser beam, and the photosensitive drum 10 is biased by the spring 62 and is in contact with the intermediate transfer drum 20 at an appropriate pressure. Therefore, the pressure fluctuation at the contact point of both drums is absorbed by the displacement of the shaft 10a. The displacement of the shaft 10a is the displacement of the surface of the photosensitive drum 10, but since this displacement is the displacement in the incident direction of the laser beam, the disturbance of the image on the surface of the photosensitive drum hardly occurs.

Although the contact pressure is applied by compression of the spring in FIGS. 1 and 2, the spring may be arranged below the photosensitive drum shaft and applied by pulling the spring.

3 and 4 show application examples of this example. Figure 3
FIG. 4 is a side view, and FIG. 4 is a detailed view of essential parts of FIG.

When the blade type cleaner 15 is used for cleaning the photosensitive drum, the positional deviation between the photosensitive drum and the cleaning blade may become a problem. In such a case, as shown in FIGS. 3 and 4, the end surface of the cleaner 15 is fixed to the side surface of the linear guide 61 so that the photosensitive drum 10 and the cleaning blade can be integrated and simultaneously displaced. Even when the change in the gap amount between the developing device and the photosensitive drum poses a problem, although not shown, a unit in which the photosensitive drum and the developing device are integrated may be similarly configured.

A second embodiment is shown in FIGS.

FIG. 5 is a side view showing the outline of the photosensitive drum shaft support structure 70 of this embodiment, and FIG. 6 is a perspective view showing the details of the photosensitive drum shaft support structure 70.
The swing arm 71 and the spring 72 are provided.
The swing arm 71 is rotatable around a support shaft 73, and the shaft 10 a of the photosensitive drum 10 is supported by the tip of the swing arm 71. The spring 72 is the swing arm 7
The leading end of the photosensitive drum 10 is biased so that the photosensitive drum 10 is in contact with the intermediate transfer drum 20 with an appropriate pressure.

In FIG. 6, 65c is a hole for supporting the spindle 73, 71a is a hole for fitting the shaft 10a, and 71b is a hole for fitting the spindle 73. As described above, in the case of this example, the shaft 10a of the photosensitive drum is supported by the swing arm 71 and is displaced in an arc shape. However, if the length of the swing arm 71 is set sufficiently larger than the displacement of the shaft 10a, The moving direction of the shaft 10a can be made substantially a straight line in the incident direction of the laser beam, and the same effect as the previous example can be obtained.

This is shown in the following mathematical expression using FIG. In FIG. 7, the maximum swing angle θ of the swing arm has a relation of y = r sin θ with respect to the length r of the swing arm and the maximum relief amount y of the drum. From this, the drum horizontal displacement maximum amount x becomes x = r−r cos θ = r−r cos (sin ⁻¹ (y / r)).

Specifically, for example, arm length r = 100
mm, maximum clearance y = 1 mm, horizontal displacement maximum x
= 0.005 mm, which corresponds to 5000 dpi, which is sufficient performance for a general color laser printer having a maximum of several hundreds dpi. When this swing arm is used, as the contact pressure applying means,
A torsion spring may be used in addition to the illustrated spring. In this case, the torque generated by the torsion spring is applied to the swing arm 71.
To generate a contact pressure.

Also in the case of this example, when a positional deviation between the photosensitive drum and the cleaning blade or a change in the gap amount between the developing device and the photosensitive drum poses a problem, a cleaner and a developing device are integrated with the photosensitive drum. Just do it.

[0026]

As described above, according to the present invention, it is possible to easily control the contact pressure between the photosensitive drum and the intermediate transfer drum. In particular, color shift in an apparatus using a color developing system, It is possible to significantly improve print unevenness and extend life.

[Brief description of drawings]

FIG. 1 is a side view showing an outline of the structure of a recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a photosensitive drum shaft support structure of the first embodiment of the present invention.

FIG. 3 is a side view showing an application example of the first embodiment of the present invention.

FIG. 4 is a detailed view of a main part of FIG.

FIG. 5 is a side view showing an outline of a photosensitive drum shaft support structure according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing details of the support structure of FIG.

FIG. 7 is an operation explanatory view of the photosensitive drum shaft support structure according to the second embodiment of the present invention.

FIG. 8 is a side view showing an outline of the structure of a conventional color recording apparatus.

[Explanation of symbols]

 10 Photosensitive Drum 10a Shaft 11, 12, 13, 14 YMCK Each Color Developing Device 20 Intermediate Transfer Drum 50 Exposure System 60, 70 Photosensitive Drum Shaft Support Structure

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication G03G 15/01 111 A 114 A 21/00 118

Claims (1)

[Claims] 1. An electrostatic latent image is formed on a surface of a charged photosensitive drum (10) by laser beam exposure, the electrostatic latent image is developed, and the developed toner image is transferred to an intermediate transfer drum (20).
In the recording apparatus of the transfer type, the axis (10a) of the photosensitive drum (10) is supported so as to be displaceable in the laser beam incident direction.