JP3244607B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus,
In particular, the present invention relates to an optical printer configured to remove a toner remaining on a photoconductor by always bringing a blade into close contact with the photoconductor.

[0002]

2. Description of the Related Art In an optical printer for forming an image by using an electrophotographic technique, a surface of a photoreceptor such as a drum or a belt is uniformly charged, and the surface of the photoreceptor is formed by exposing the surface to a laser beam. In this configuration, a toner image is formed by developing an electrostatic latent image, and then the toner image is transferred and fixed on paper to form an image. On the other hand, the toner remaining on the photoconductor after the toner image has been transferred onto the paper is removed by a rectangular blade that is always in close contact with the photoconductor, and then the charge remaining on the photoconductor is erased by an erase lamp. After removal, the process proceeds to the subsequent steps of charging, exposure, development, and transfer so that an image can be repeatedly formed. By the way, since the photoreceptor is a regular exchange product, in the case of a belt-shaped photoreceptor, it is very effective to form the photoreceptor from a sheet material in consideration of manufacturing cost and economical efficiency.

In such a photoreceptor, since a photosensitive layer is applied to a sheet material and then formed into a cylindrical shape by joining both ends of the sheet, a seam remains as a step on the front and back surfaces of the belt. Accordingly, there has been a problem that the speed of the photoconductor fluctuates due to a load fluctuation due to an impact when the blade passes through the seam, and the electrostatic latent image is disturbed and appears as density unevenness on the image. For this reason, for example, as disclosed in Japanese Patent Application Laid-Open No.
Means for mounting the cleaning member not parallel to the longitudinal direction has been proposed.

[0004]

However, in the case of a belt-shaped photoreceptor, in order to stably bring the blade into close contact with the photoreceptor, a blade receiver for receiving the pressing force of the blade by a spring on the back surface of the photoreceptor facing the blade. Set up a table,
It is configured to keep the contact angle, pressing force, etc. of the blade constant. However, the photoreceptor is sandwiched between the blade and the blade cradle, which causes a shock when the seam of the photoreceptor passes through the gap. A defect that disturbs the image and causes density unevenness on the image occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a good image by alleviating an impact when a seam of a photoreceptor passes between a blade and a blade cradle and reducing a speed fluctuation of the photoreceptor. It is to provide an electrophotographic apparatus which can be used.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to mount a blade at an angle .theta. With respect to the direction of a seam formed on the surface of a photoreceptor, and to tilt a blade support at an angle .phi. And attach the
The blade support in the direction of the seam on the photoreceptor surface.
Blade inclination direction opposite to the configuration Ru is inclined of that, or the configuration which has been subjected to rounded sides flaps portion of the photoreceptor inlet side and the outlet side, between which is sandwiched the blade and blade cradle seam of the photoreceptor This can be achieved by alleviating the impact when passing through and reducing fluctuations in the speed of the photoconductor.

[0007]

According to the present invention, the impact when the seam of the photoreceptor passes between the blade and the blade cradle is dispersed, so that the fluctuation of the photoreceptor speed is reduced, and as a result, the density unevenness is reduced. No good images can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional side view of a color laser printer. A photosensitive belt 2 located at a central portion in a printer main body 1 forms a part of a belt cartridge 7 formed as a cartridge. Rotating roll 4,
5 and a tension roll 6 so as to be rotatably held.

The driving roll 3 and the tension roll 6 are arranged so as to form a flat developing area on the photosensitive belt 2, and the tension roll 6 and the rotating roll 5 are arranged so as to form a toner image transfer area described later.

The rotating roll 4 guides the photosensitive belt 2 so as to form a stable exposure surface on the photosensitive belt 2 for scanning exposure described later.

A driving roll 3 for driving the belt rotates so as to convey the photosensitive belt 2 at a speed of about 70 mm / s.

Under the photosensitive belt 2, a corona discharge type charger 8 and a scanning exposure unit 9 for a laser beam 9a are provided.
In addition, a blade 10 for removing toner remaining on the surface of the photosensitive belt 2 and an erase lamp 11 for removing charges remaining on the surface of the photosensitive belt 2 are arranged.

The surface of the photosensitive belt 2 is uniformly charged with a potential of about -600 V by a charger 8 and controlled by a video signal supplied from a higher-level image signal generator to generate a laser beam generated from a scanning exposure unit 9. Reference numeral 9a denotes an electrostatic latent image having a pixel density of about 300 dpi in the direction of rotation of the photosensitive belt 2 by being repeatedly deflected in a direction crossing the surface of the photosensitive belt 2 at a period of 1.225 ms to scan and expose the surface of the photosensitive belt 2. To form

On the upper side of the photosensitive belt 2, a developing device 12 is provided so as to face a developing area where the photosensitive belt 2 rotates flat.
To 15 are detachably arranged, and the respective developing devices 12 to
The electrostatic latent image is developed by rubbing the surface of the photosensitive belt 2 with the developer magnetic brush formed in 15. The gap between the photosensitive belt 2 and the developing devices 12 to 15 can be managed by contacting both ends of stays 22 and 23 fixed to the side plate of the belt cartridge 7 with gap rings provided in each developing device.

The developing device 12 uses a developer mixed with yellow (Y) toner, the developing device 13 uses a developer mixed with magenta (M) toner, and the developing device 14 A developer mixed with cyan (C) toner is used, and a developer mixed with black (B) toner is used for the developing device 15.

The developing devices 12 to 15 are selectively acted on the photosensitive belt 2 in accordance with the corresponding color of the electrostatic latent image, thereby developing each electrostatic latent image into a toner image of a corresponding color. .

In order to develop each electrostatic latent image, one developing device 12 (13 to 15) is selected to act on the photosensitive belt 2 for about 5 seconds.

The intermediate transfer drum 17 is arranged so as to rotate while being in contact with the photosensitive belt 2 positioned in the printer main body 1 at the toner image transfer area, and the toner image formed on the surface of the photosensitive belt 2 The image is transferred in the image transfer area.

The intermediate transfer drum 17 also rotates at a speed of about 70 mm / s. This speed is equal to the rotation speed of the photosensitive belt 2, and the movements of the photosensitive belt 2 and the intermediate transfer drum 17 are synchronized.

Around the intermediate transfer drum 17, a pre-charger 18, a transfer roll 19 and a drum cleaner 20 are arranged so as to face the outer peripheral surface of the intermediate transfer drum 17. The toner images are sequentially transferred so as to be superimposed to form a color toner image.

The preliminary charger 18 is a corona discharger,
Corona discharge is generated by urging the surface of the intermediate transfer drum 17 to provide a charge that assists the transfer of the completed color toner image onto the recording paper 21.

The drum cleaner 20 includes an intermediate transfer drum 17
Is movable toward and away from the surface. In the process of forming a color toner image by superimposing and transferring a plurality of single-color toner images from the photosensitive belt 2 to the intermediate transfer drum 17, the drum cleaner 20 is operated so as to be separated from the outer peripheral surface of the intermediate transfer drum 17. The completed color toner image is recorded on the outer peripheral surface of the intermediate transfer drum 17 on a recording paper 21.
After the transfer to the intermediate transfer drum 17, the drum cleaner 20 removes toner remaining on the surface of the intermediate transfer drum 17.
It is operated to touch this surface.

The paper feed mechanism is installed in a space below the scanning exposure unit 9 and is provided with the recording paper 2 stored in the paper feed cassette 24.
1 is extracted by the paper feed roll 25 and sent out. A registration roll 26 for adjusting the transport timing of the color toner image formed on the surface of the intermediate transfer drum 17 and the recording paper 21 for transferring the toner image is provided between the paper feed roll 25 and the transfer roll 19. The recording paper 21 fed from 25 is sent to the transfer roll 19 with the transport timing adjusted.

The registration roll 26 holds the recording paper 21 by about 70
It rotates so as to convey at mm / s (the same speed as the photosensitive belt 2).

A transfer guide 27 is provided downstream of the transfer roll 19.
And a fixing unit 28 and a paper discharge roll 29. A paper discharge tray 30 on which the printed material (the recording paper 21 on which the toner image is fixed) sent from the paper discharge roll 29 is placed is a printer main body 1.
Formed on the upper surface of the substrate.

The printer body 1 has a built-in control circuit for controlling the operation of the color laser printer, but its illustration is omitted.

The photosensitive belt 2 is formed into a belt shape by applying a photosensitive layer to a sheet material such as PET and joining the both ends of the sheet after considering the economics such as manufacturing cost. Therefore, a seam 31 as shown in FIG.

As shown in FIG. 3, a pressing force is applied to the blade 10 by a spring 33 attached to a blade holder 32, and a cartridge side plate 35 of the belt cartridge 7 is formed.
A pressing force is applied about a support shaft 34 supported by the photosensitive belt 2 as a rotation center, and a cleaning force is applied to the photosensitive belt 2 such that the photosensitive belt 2 is sandwiched between the photosensitive belt 2 and a blade receiving base 36 on the back surface. The seam 31
When passing through, impact occurs. For this reason, the speed of the photosensitive belt 2 fluctuates due to load fluctuation. On the photosensitive belt 2, a seam 31 is detected and an image for two colors (in the case of a color image) or an image for two pages (in the case of a single color) is formed on the other surface of the photosensitive belt 2 Can be.

The blade 10 is always in close contact with the surface of the photosensitive belt 2, and after transferring the toner image formed on the surface of the photosensitive belt 2 to the outer peripheral surface of the intermediate transfer drum 17, the toner remaining on the photosensitive belt 2 without being transferred When the toner is removed, the state of contact at the seam 31 changes rapidly, so that the load on the photosensitive belt 2 fluctuates.

Further, the photosensitive belt 2 is stretched by rotating rolls 4 and 5, and the blade receiving base 36 is connected to a joint 31.
Also, when the sheet passes through, an impact is generated, and the load on the photosensitive belt 2 fluctuates.

The laser beam 9a is controlled by a video signal supplied from an image signal generator, and forms a desired electrostatic latent image by rotating the photosensitive belt 2 at a constant rotation speed. When a color image or a monochrome image is continuously printed in this process, the seam 31 passes between the blade 10 and the blade receiving base 36 during the formation of the electrostatic latent image, and the speed of the photosensitive belt 2 is reduced. Fluctuates and disturbs the electrostatic latent image being formed, and appears as density unevenness in the toner image. Therefore, the seam 31 is
It is necessary to alleviate the impact when passing through the zero and blade receiving base 36.

FIG. 4 shows a state where the seam 31 of the photosensitive belt 2 is
The blade 10 was inclined at an angle θ (in the experiment, inclined from 0.5 to 5 degrees), and the blade support 36 was inclined at an angle φ (in the experiment, inclined from 1 to 10 degrees). 1 shows the configuration. The blade 10 is tilted downward to the right with respect to the seam 31 of the photosensitive belt 2, and
6 is inclined to the lower left, so that the shock generated when the seam 31 passes between the blade 10 and the blade cradle 36 is dispersed. As a result of the experiment, it was confirmed that when the angle was set, the impact was reduced as shown in the figure. The angle at which the impact force was the smallest as a result of this experiment was θ = 1 degree and φ = 3. However, if both the blade and the blade holder are provided at an angle with respect to the photosensitive member seam, the impact force is small. It has been confirmed that the occurrence of the occurrence can be reduced as compared with the case where the joints are parallel.

Conventionally, since the blade 10 and the blade holder 36 are mounted in parallel with the seam 31, an impact when the seam 31 passes largely appears as a temporary speed fluctuation of the photosensitive belt 2 as shown in FIG. I was

On the other hand, when the blade 10 and the blade holder 36 are attached to the seam 31 at an angle,
Since the impact when the seam 31 passes is dispersed, the speed fluctuation of the photosensitive belt 2 is reduced as shown in FIG.

Here, FIGS. 5 and 6 take time on the horizontal axis,
The vertical axis indicates the rate of change of the speed V of the photosensitive belt 2 with respect to the set speed V0.

Therefore, by adopting the above configuration, the impact when the seam 31 passes can be reduced and the speed fluctuation of the photosensitive belt 2 can be reduced, so that a good image without density unevenness can be obtained.

In this embodiment, the configuration in which the blade receiving base 36 is inclined has been described. In addition, as shown in FIG.
When the ratio of the seam 31 to the step H is changed, the density unevenness is improved as shown in FIG. In particular, if the ratio of the radius R to the step H is set to 20 or more, a good image with less density unevenness can be obtained.

In addition, there is an effect of reducing density unevenness by reducing the friction coefficient μ of the blade receiving base 36, and the relationship is as shown in FIG. In particular, the blade holder 36
Is less than 0.2, the density unevenness is reduced. In order to make the friction coefficient μ of the blade holder 36 equal to or less than 0.2, a metal having a surface roughness of 1 μm or less by buffing or the like is used for the blade holder 36. In addition, a desired friction coefficient can be obtained by coating the blade receiving base 36 with a fluorine resin or the like.

As described above, the speed fluctuation of the photosensitive belt 2 is caused by the sharp step H of the seam 31 generated on the front and back surfaces of the photosensitive belt 2.
Therefore, as shown in FIG. 9, for example, a polyester resin, an acrylic resin, or the like may be applied on the seam 31 to form the step H gently.

[0041]

According to the present invention, it is possible to reduce the impact when the seam of the photosensitive member passes between the blade and the blade holder. Image can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a color laser printer according to the present invention.

FIG. 2 is a sectional view showing a joint of the photosensitive belt according to the present invention.

FIG. 3 is a side view showing a blade mounting method according to the present invention.

FIG. 4 is an explanatory view showing a mounting state of a blade and a blade receiving base according to the present invention.

FIG. 5 is an explanatory diagram of a speed variation of a photosensitive belt caused by attaching a conventional blade and a blade receiving base.

FIG. 6 is an explanatory diagram of speed fluctuation of the photosensitive belt due to attachment of the blade and the blade receiving base according to the present invention.

FIG. 7 is a diagram illustrating the relationship between the ratio of the roundness R of the corner portion of the blade receiving base and the step H of the seam and the image quality (density unevenness) according to the present invention.

FIG. 8 is an explanatory diagram showing the relationship between the friction coefficient of the blade holder according to the present invention and the image quality (density unevenness).

FIG. 9 is a cross-sectional view showing a state where a seam of the photosensitive belt according to the present invention is coated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printer body, 2 ... Photosensitive belt, 3 ... Drive roll,
4, 5: rotating roll, 6: tension roll, 7: belt cartridge, 8: charger, 9: scanning exposure unit,
10 ... blade, 11 ... erase lamp, 12-15 ...
Developing device, 17: intermediate transfer drum, 18: preliminary charger,
19: transfer roll, 20: drum cleaner, 25: paper feed roll, 26: registration roll, 28: fixing device, 29 ...
Discharge roll, 31 ... seam, 32 ... blade holder,
33 ... spring, 34 ... support shaft, 35 ... cartridge side plate, 3
6 ... Blade cradle.

Continued on the front page (72) Inventor Katsumasa Mikami 1-1-1 Higashitagacho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Electrical Equipment Division, Taga Headquarters (72) Inventor Tetsuro Akasaki Higashitagamachi, Hitachi City, Ibaraki Prefecture No. 1-1, Hitachi, Ltd. Electrical Equipment Division, Taga Headquarters (56) References JP-A-54-110847 (JP, A) JP-A-63-301984 (JP, A) JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 21/00 350

Claims (2)

(57) [Claims] 1. A charging device for charging a belt-shaped photoconductor, an exposure device for exposing the charged photoconductor to form an electrostatic latent image, and a developing device for developing the electrostatic latent image to form a toner image on the photoconductor. Developing means for forming, transfer means for transferring the toner image to the transfer material, fixing means for fixing the transfer material on which the toner image has been transferred, and cleaning means for removing the toner remaining on the photoreceptor after the transfer with a blade. An electrophotographic apparatus having a configuration in which the blade is attached at an angle θ with respect to a seam direction generated on the surface of the photoreceptor. Attach the table at an angle φ to the direction of the seam generated on the back of the photoreceptor, and attach the blade.
Move the cradle to the direction of the seam
An electrophotographic apparatus characterized by being inclined in a direction opposite to the inclination direction of the card . 2. A belt for uniformly charging a belt-shaped photosensitive member.
Forming a latent image by exposing the charged photosensitive member
Exposure means, and develops the electrostatic latent image to form a toner image on the photoreceptor.
Developing means for forming and transfer for transferring a toner image to a transfer material
Means and a fixing means for fixing the transfer material on which the toner image has been transferred.
Step and blade to remove toner remaining on photoreceptor after transfer
Cleaning means for removing the blade,
Incline to angle θ with respect to the seam direction generated on the surface of the light body
In the electrophotographic apparatus having the attached structure, the blade
A blade support on the back surface of the photoreceptor opposite to
Of the blade cradle parallel to the direction perpendicular to the optical element transport direction.
The photoreceptor inflow side or the photoreceptor inflow side and discharge side
The corners on both sides are rounded, the radius of the roundness is R, and the photoconductor
When the height of the seam formed on the back surface is H, the relation of R> H
Electrophotographic apparatus being characterized in that the engagement.