JPH08292689A - Electrophotographic device - Google Patents

Abstract

PURPOSE: To uniformly secure cleaning force in the longitudinal direction and to obtain a good image with high reliability by forming a cleaning blade into a shape capable increasing strength on both ends of the blade supporting board of the cleaning blade. CONSTITUTION: The cleaning blade has the shape capable of increasing the strength on both ends of the blade supporting board 10b, and a triangle shape is provided on both ends of the board 10b based on the flexibility chart of the blade. For example, width W1 is about 0.2 to 0.5mm, length (l) is about 15 to 30mm, and thickness is about 1.5 to 2.0mm. The shape coming close to the triangle whose height is gradually high and which does not have a step is the best. The toner, which is not transferred to the photoreceptor and remains, leaks from the part of the step if any step exists, and defective cleaning occurs and the stripe occurs on the image. Consequently, the shape by which the strength on both ends of the board 10b of the blade is increased, is suitable, and thereby, the remaining toner can be surely cleaned.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Optical printers using electrophotography are
By uniformly charging the surface of the photoconductor such as a drum or belt and exposing it to laser light, the electrostatic latent image formed on the surface of the photoconductor is developed to form a toner image. The image is created by transferring and fixing to. On the other hand, after the toner that has not been transferred to the photoconductor belt after the toner image is transferred to the paper is removed by a cleaning blade that is in close contact with the photoconductor belt at all times, the charge remaining on the photoconductor is erased. Removed with
By moving to the next charging, exposure, development, and transfer processes, it is possible to repeatedly create images.

Generally, the cleaning method is roughly divided into two, that is, a means using a fur brush and a blade. Among them, the means using a blade includes a counter and trailing. In particular, as disclosed in Japanese Patent Publication No. 4-73798, in which a blade is used for cleaning a belt-shaped photosensitive member, a configuration in which the belt is pressed against a horizontal portion of the belt and used is disclosed. Although not disclosed in the above-mentioned publication, the blade is a spring attached to the blade supporting plate, and a pressing force is applied around the support shaft supported by the cartridge side plate as the center of rotation, so that the blade receiver on the back surface of the photosensitive belt is received. The required cleaning force is evenly applied to the photosensitive belt by sandwiching the photosensitive belt with the stand. Further, the blade ensures a proper contact angle with the photoconductor belt.

[0004]

However, if the dynamic pressing force, that is, the cleaning force, that the blade is brought into close contact with the photosensitive belt, the rigidity of the cleaning blade, and the contact angle become improper, the image is not transferred to the photosensitive belt. There is a problem of image defects in which the residual toner is not cleaned and streaky stains appear on the image. Since both ends of the conventional cleaning blade are not fixed, the strength is weakened, the dynamic pressing force of both ends, that is, the cleaning force is reduced, and the above-mentioned problems occur. Further, in the high-resolution electrophotographic apparatus, the particle size of the toner is further reduced, so that the above-mentioned problems are likely to occur. Where spring pressure UP
Although a means is conceivable, there has been a problem that a secondary problem such as shortening of life such as peeling of the photoconductor of the photoconductor belt occurs.

In order to stably bring the blade into close contact with the photosensitive belt, the photosensitive belt is provided with a blade pedestal on the back surface of the photosensitive belt opposite to the blade for receiving the pressing force of the blade by the spring, so that the cleaning force is uniform. Is configured to keep. However, as described above, the blade of the cleaning blade and the blade support plate have the same width in the longitudinal direction, and the blades are free on the outer sides of both ends. As a result, the toner remaining without being transferred to the photoreceptor belt is not cleaned, and a problem occurs that streaks are generated on the image.

An object of the present invention is to obtain a highly reliable and good image by ensuring a dynamic pressing force of the blade, that is, a cleaning force, in the longitudinal direction for bringing it into close contact with the photoreceptor belt. To provide a device.

[0007]

[Means for Solving the Problems] A structure in which the strength of both ends of a blade supporting plate of a cleaning blade is increased, or a shape of a blade linear pressure portion that is in close contact with a photosensitive belt is concave. Or, the support plate shape of the blade in the longitudinal direction has a convex shape from both ends in the center, or a combination of the above, so that the cleaning force remains constant and even without being transferred to the photoreceptor belt. Toner can be reliably cleaned.

[0008]

According to the present invention, the dynamic pressing force of the cleaning blade, which is in close contact with the photosensitive belt, that is, the cleaning force is uniform in the longitudinal direction, and the cleaning performance of the cleaning blade is improved. As a result, a good image without streaky stains can be obtained.

[0009]

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 vertical cross-sectional side view of a color laser printer, in which a photosensitive belt 2 located in the center of the printer body 1 forms a part of a belt cartridge 7 formed as a cartridge, and a drive roll 3 is provided. , Is stretched around the rotating rolls 4, 5 and the tension roll 6 and is rotatably held. Drive roll 3 and tension roll 6
Are arranged so as to form a flat development area on the photoreceptor belt 2. Further, the tension roll 6 and the rotation roll 5 are arranged so as to form a toner image transfer area described later. Further, the rotating roll 4 guides the photosensitive belt 2 so as to form a stable exposure surface for scanning exposure, which will be described later, on the photosensitive belt 2. Drive roll 3 for driving the belt
Rotates so as to convey the photosensitive belt 2 at a predetermined speed.

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

The surface of the photosensitive belt 2 is uniformly charged with a predetermined electric potential by a charger 8, and a laser beam 9a generated from a scanning exposure unit 9 under the control of a video signal given by an upper image signal generator. Is the photoconductor belt 2
The surface of the photoreceptor belt 2 is scanned and exposed by being repeatedly deflected in a direction traversing the surface of the photoreceptor belt 2 to form an electrostatic latent image of a predetermined pixel density in the rotating direction of the photoreceptor belt 2.

On the upper side of the photoconductor belt 2, the developing devices 12 to 15 are detachably arranged so as to oppose to the developing region in which the photoconductor belt 2 rotates flatly.
2-15 developer magnetic brush formed by photoconductor belt 2
The surface of is rubbed to develop an electrostatic latent image. Photoconductor belt 2
The gap between the developing devices 12 to 15 can be managed by contacting both ends of the stays 22 and 23 fixed to the side plate of the belt cartridge 7 with the gap ring provided in each developing device.

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

Each of the electrostatic latent images is developed into a toner image of a corresponding color by selectively operating the developing devices 12 to 15 on the photosensitive belt 2 in accordance with the corresponding color of the electrostatic latent image. To do.

A developing device 1 for developing each electrostatic latent image.
One of 2 to 15 is selected, and the time to act on the photosensitive belt 2 is about 5 seconds.

The intermediate transfer drum 17 is arranged so as to rotate while attracting and contacting with the photosensitive belt 2 positioned in the printer main body 1 by electrostatic force in the toner image transfer area. The toner image formed on the surface of the photoconductor belt 2 is transferred in this toner image transfer area.

The intermediate transfer drum 17 also rotates at a predetermined speed. This is a speed equal to the rotation speed of the photoconductor belt 2, and the motions of the photoconductor belt 2 and the intermediate transfer drum 17 are synchronized.

Around the intermediate transfer drum 17, a pre-charging device 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. Toner images are sequentially transferred so as to be polymerized to form a color toner image.

The precharger 18 is a corona discharger,
A corona discharge is generated by being urged to provide a charge for supporting the transfer of the completed color toner image onto the recording paper 21 on the surface of the intermediate transfer drum 17.

The drum cleaner 20 is an intermediate transfer drum 17.
Of the photosensitive belt 2 which can be moved toward and away from the surface of
From the intermediate transfer drum 17 to the intermediate transfer drum 17 in a superimposed manner, in the process of forming a color toner image, it is operated away from the outer peripheral surface of the intermediate transfer drum 17, and completed on the outer peripheral surface of the intermediate transfer drum 17. After the transferred color toner image is transferred onto the recording paper 21, it is operated so as to be in contact with the surface of the intermediate transfer drum 17 in order to remove the residual toner.

The paper feeding mechanism is installed in the space below the scanning exposure unit 9 and the recording paper 2 stored in the paper feeding cassette 24 is provided.
1 is extracted by the paper feed roll 25 and sent out. A registration roll 26, which aligns the color toner image formed on the surface of the intermediate transfer drum 17 and the conveyance timing of the recording paper 21 onto which the toner image is transferred, is provided between the paper feed roll 25 and the transfer roll 19 and The transfer timing of the recording paper 21 sent from 25 is adjusted and sent to the transfer roll 19.

The registration roll 26 rotates so as to convey the recording paper 21 at a predetermined speed (the same speed as the photosensitive belt 2 and the intermediate transfer drum 17).

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

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

In consideration of manufacturing cost and other economical factors, such a photoreceptor belt 2 may be formed by applying a photosensitive layer to a sheet material such as PET and then joining both ends of the sheet to form a belt shape. For this reason, there are seams 16 as shown in FIG. Blade 10
Reference numeral a is a spring 31 attached to the blade support plate 10b, and a pressing force is applied to the support shaft 32 supported by the cartridge side plate 33 as a rotation center, and the blade 10a secures a contact angle θ with the photosensitive belt 2. The photoconductor belt 2 is sandwiched between the photoconductor belt 2 and the blade pedestal 34 on the back surface of the photoconductor belt 2 so that a necessary cleaning force is applied to the photoconductor belt 2.

An image of two colors (in the case of a color image) or two pages of an image (in the case of a single color) is detected on the surface of the photosensitive belt 2 at the other portions by detecting the seam 16 on the photosensitive belt 2. ) Can be formed.

The cleaning blade 10 shown in FIG. 4 is shaped so as to increase the strength of both ends of the blade supporting plate 10b. Triangular shapes based on the deflection diagram of the blade are provided at both ends of the blade support plate 10b. In this embodiment,
The width W ₁ is about 0.2 to 0.5 mm, and the length l ₁ is 15 to 30 mm.
The thickness is about 1.5 to 2.0 mm. It is best to have a shape close to a triangle with no step and the height gradually increasing. If there is even a small step, the toner remaining on the photoconductor belt 2 without being transferred from the step portion slips off and cleaning failure occurs. However, streaks occur on the image. FIG. 7 shows the static pressing force distribution of the blade 10a and the influence of the image quality. The current cleaning blade having no triangular shape at both ends of the blade supporting plate 10b also shows that the pressing force distribution satisfies the region where a good image can be obtained. However, this pressing force distribution is static, and as shown in FIG. 8, when cleaning actually starts, the dynamic pressing force, that is, the cleaning force, particularly decreases at both ends of the blade 10a, and streaks appear on the image. appear. Therefore, it is necessary to keep the dynamic pressing force, that is, the cleaning force uniform, and a cleaning blade of the present embodiment, which has a shape in which both ends of the blade supporting plate 10b are increased in strength, is suitable as shown in FIG. As a result, the toner that has not been transferred to the photoreceptor belt and remains can be reliably cleaned, and a good image without streaky stains can be obtained. However, the cleaning blade 10 is
Thickness is about 1.5-2.0 mm, length is about 150-170 mm, hardness of blade 10a is about 70-75 °, spring 3
This is an example in the case of the cleaning blade 10 in which the pressing force of 1 is about 0.8 to 1.5 kg.

In FIG. 5, the blade 10a on the side that is in close contact with the photosensitive belt 2 is concave, and the width W ₂ at both ends is increased from the center by about 0.1 to 0.2 mm. Furthermore, FIG.
In the longitudinal direction of the cleaning blade, the central height H is raised from both ends to a convex shape of about 0.1 to 0.3 mm.
Although the same effects are obtained in each of FIGS. 4, 5, and 6, the cleaning performance can be improved even in a structure in which they are combined.

[0030]

According to the present invention, the dynamic pressing force of the cleaning blade, which is in close contact with the photoreceptor belt, that is, the cleaning force is uniform in the longitudinal direction, the cleaning performance of the cleaning blade is improved, and the streak pattern is formed. It is possible to obtain a good image with high reliability and free from stains.

[Brief description of drawings]

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

FIG. 2 is a side view showing a cleaning blade attaching method according to the present invention.

FIG. 3 is an explanatory view showing a conventional cleaning blade.

FIG. 4 is an explanatory diagram showing a cleaning blade according to a first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a cleaning blade according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a cleaning blade according to a third embodiment of the invention.

FIG. 7 is a diagram for explaining the relationship between the static pressure distribution of the cleaning blade and the image quality (cleaning failure).

FIG. 8 is a diagram illustrating the relationship between the dynamic pressure distribution (cleaning force) of the cleaning blade and the image quality (cleaning failure).

[Explanation of symbols]

1 ... Printer body, 2 ... Photosensitive belt, 3 ... Drive roll, 4, 5 ... Rotation roll, 6 ... Tension roll, 7 ...
Belt cartridge, 8 ... Charger, 9 ... Scanning exposure unit, 10 ... Cleaning blade, 11 ... Erase lamp, 12-15 ... Developing device, 16 ... Seam, 17 ... Intermediate transfer drum, 18 ... Precharger, 19 ... Transfer Roll, 2
0 ... Drum cleaner, 25 ... Paper feed roll, 26 ... Registration roll, 28 ... Fixer, 29 ... Paper discharge roll, 31 ... Spring, 32 ... Spindle, 33 ... Cartridge side plate, 34 ... Blade pedestal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isamu Terashima 1-1-1, Higashitaga-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Electric Appliances Division, Electric Appliances Division Taga Headquarters (72) Tetsuro Akasaki Higashi-taga, Hitachi-shi, Ibaraki 1-1-1 Machi In the electrical equipment division of Hitachi Ltd., Hitachi, Ltd. (72) Inventor Tomio Hayano 1-1-1 Higashitaga-cho, Hitachi, Ibaraki Prefecture Inside the electrical equipment division of Hitachi, Ltd. Taga Headquarters

Claims (3)

[Claims] 1. A charging unit for uniformly charging a belt-shaped photosensitive member, an exposing unit for exposing the charged photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image on the photosensitive member. A developing unit that forms a toner image, a transfer unit that transfers the toner image to a transfer material, a fixing unit that fixes the transfer material on which the toner image is transferred, and a toner that remains on the photoconductor after the transfer is removed by a blade. An electrophotography having a blade support plate, which is equipped with a cleaning means and a charge removing means for removing charges remaining on the photoconductor after transfer, and which is attached by inclining the blade with respect to the rotational direction of the photoconductor so as to be a counter. In the apparatus, a blade pedestal is provided on the back surface of the photosensitive belt facing the cleaning blade, and the strength is increased by adjusting the shape of the blade support plate to the deflection diagram of both ends of the cleaning blade. Electrophotographic apparatus being characterized in that the that shape. 2. A charging unit for uniformly charging a belt-shaped photosensitive member, an exposing unit for exposing the charged photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image on the photosensitive member. A developing unit that forms a toner image, a transfer unit that transfers the toner image to a transfer material, a fixing unit that fixes the transfer material on which the toner image is transferred, and a toner that remains on the photoconductor after the transfer is removed by a blade. In an electrophotographic apparatus having a cleaning means and a charge removing means for removing charges remaining on the photoconductor after transfer, the blade being attached so as to be inclined with respect to the rotation direction of the photoconductor so as to serve as a counter. An electrophotographic apparatus having a blade pedestal on the back surface of the photosensitive belt facing the cleaning blade, wherein the center of the linear pressure portion of the cleaning blade is concave. 3. A charging unit for uniformly charging a belt-shaped photosensitive member, an exposing unit for exposing the charged photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image on the photosensitive member. A developing unit that forms a toner image, a transfer unit that transfers the toner image to a transfer material, a fixing unit that fixes the transfer material on which the toner image is transferred, and a toner that remains on the photoconductor after the transfer is removed by a blade. In an electrophotographic apparatus having a cleaning means and a charge removing means for removing charges remaining on the photoconductor after transfer, the blade being attached so as to be inclined with respect to the rotation direction of the photoconductor so as to serve as a counter. , Having a blade pedestal on the back surface of the photosensitive belt opposite to the cleaning blade, the shape of the blade support plate in the longitudinal direction,
An electrophotographic apparatus having a convex shape in the center from both ends.