JP2003162147A - Developing device and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the developer sealing constitution of a developing device where a blade lower seal for sealing space between a developing blade and a developing container is not brought into contact with the developing blade at the acting position of the developing blade where the developing blade is brought into press-contact with a developing roller, whereby a gap at this part is stably sealed. <P>SOLUTION: The developing device has an extension area obtained by extending the edge position of the developing blade 332 toward the end side in the longitudinal direction of the blade 332 further than the edge position of a blade supporting plate 353 at both ends in the longitudinal direction of the blade 332, and the supporting plate 353 has a chamfer part 359 whose angle part is removed in order to eliminate a level difference between the surface of the developing blade and the plate 353 in the extension area, and at least an end seal 352 is brought into contact with the chamfer part 359 so as to seal it. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus and a developing device for the electrophotographic image forming apparatus.

Here, the electrophotographic image forming apparatus forms an image on a recording medium by using an electrophotographic image forming system. Then, examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, a word processor, and the like.

The developing device is a unit in which a developing means for developing a latent image formed on an electrophotographic photosensitive drum and members associated therewith are unitized.

[0004]

2. Description of the Related Art Conventionally, the following structure is known as a multicolor image forming apparatus for forming a multicolor image on a recording medium by an electrophotographic method. It arranges a plurality of developing devices, which store developers of different colors, on a rotating mechanism with respect to the electrophotographic photosensitive drum. Then, the latent image is developed by making a developing device containing a developer of a predetermined color face the photosensitive drum, and the developed image is transferred to a recording medium. Further, by performing these developing and transferring operations for each color, a multicolor image is obtained on the recording medium.

There is a cartridge structure in which the developing device is detachable from the main body of the image forming apparatus so as to reduce the maintenance work of the user.

Since the developing device has a mechanism for coating the developing roller, which is the developing means, with the developer, and stores the developer inside, there is a gap between the members so that the developer does not leak out of the developing device. A seal member is disposed at a position where the seal can be formed. The conventional seal configuration is as follows.

(1) In the case of a gap between the developing blade and the developing container, a foaming member having elasticity is usually arranged to seal the gap (seal under blade).

(2) In the case of a gap between the developing roller and the developing container, in order to improve the sliding condition with the rotating developing roller, the surface layer is sealed with a member made of a raised member such as felt (end seal). ).

(3) A gap is formed between the lower blade seal and the end seal due to the variation in the positioning (pasting) tolerance of the lower blade seal and the end seal. By designing this part at the position where the end seal and the lower blade seal are inserted in advance, the side surface of the lower blade seal is crushed by the end seal so that no gap can be created even if the sticking positions of the seal members are misaligned. I was doing.

[0010]

In the above construction, since the developing blade is a thin elastic member, it is attached to the developing container which is joined to the blade supporting sheet metal for reinforcement and stores the developer.

Conventionally, a blade lower seal, which is a foaming member, has been arranged and sealed in the gap between the developing blade and the developing container, but this has the following problems.

(1) The developing blade is in contact with the lower blade seal with a certain amount of penetration, and the developing blade is pushed by the pressure of the lower blade seal. Therefore, the contact pressure of the developing blade against the developing roller becomes high due to the influence of the blade lower seal.

(2) Since the under-blade seal must be arranged at a position where there is no blade supporting sheet metal on the surface of the developing blade, there must be some distance between the developing blade tip and the blade supporting sheet metal tip. Because of that,
There was a restriction on the setting of the free length of the developing blade.

(3) Due to the arrangement relationship between the developing container and the developing blade, the seating surface of the developing container cannot be secured between the tip of the developing blade and the tip of the blade supporting sheet metal, and the lower blade seal should be arranged. It could be difficult.

The present invention solves the above-mentioned problems.
The purpose is to keep the under-blade seal that seals between the developing blade and the developing container from contacting the developing blade at the position where the developing blade presses the developing roller, and to stably seal the gap in this part. The present invention provides a developer seal structure for a developing device.

[0016]

A typical constitution according to the present invention for achieving the above object is to provide a developing roller for developing a latent image formed on an electrophotographic photosensitive drum, and the developing roller. An elastic developing blade that is pressed against the developing roller to apply a thin layer of developer, a blade support member that is joined to the developing blade to reinforce the developing blade, the developing roller, the developing blade, and A frame body for holding a blade support member, and a lower blade seal for filling and filling a gap between the blade support member and the frame body, and at both ends in the longitudinal direction of the developing blade, the tip of the developing blade. The position has an extension region extended to the longitudinal end side from the tip position of the blade support member, and the blade support member has the development blade surface in the extension region. Has a chamfer corner portions are removed to eliminate the step between, wherein at least said end seal to seal in contact with the chamfer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a color image forming apparatus according to the present invention will be described below with reference to the drawings.

In the following description, the front side of the apparatus refers to the surface on the upstream side of conveyance of the recording medium from the transfer process to the fixing process (right side in FIG. 1), and the left and right sides of the apparatus main body and the process cartridge are the front side of the apparatus. Seen from the left or right. The longitudinal direction is a direction that is parallel to the surface of the recording medium and intersects (substantially orthogonal) the conveying direction of the recording medium.

First Embodiment (Outline of Image Forming Operation of Color Image Forming Apparatus) First, the overall configuration of the color image forming apparatus will be schematically described with reference to FIG.

FIG. 1 is an embodiment of a color electrophotographic image forming apparatus embodying the present invention, and is a vertical cross-sectional view showing a schematic structure of a color laser beam printer in which a developing cartridge, a drum cartridge, and an intermediate transfer body unit are mounted in an image forming apparatus main body. It is a side view.

As shown in FIG. 1, the main body of this color image forming apparatus irradiates an optical image based on image information from an exposing means 3 to form an image agent image on an image carrier (hereinafter referred to as "photosensitive drum") 1. (Hereinafter referred to as “toner image”) is formed. And
In synchronism with the formation of the toner image, the transfer material is conveyed by a conveying means including a pickup roller 18, a conveying roller pair 19, a registration roller pair 7, etc., and the toner image formed on the photosensitive drum 1 is transferred to the intermediate transfer body 5a. Transcribed.

Next, the toner image on the intermediate transfer member 5a is transferred to the transfer material by the second transfer means, and the transfer material is conveyed to the fixing means 8 having the pressure roller 8a and the heating roller 8b to transfer the transfer toner. The image is fixed and discharged to the discharge unit 10.

The image forming process will be described in more detail.

The photosensitive drum 1 is rotated in the direction of the arrow (counterclockwise) in FIG. 1 in synchronism with the rotation of the intermediate transfer belt 5a, and the surface of the photosensitive drum 1 is uniformly charged by the charging device 2 and exposed. For example, light irradiation of a yellow image is performed by the means 3 to form a yellow electrostatic latent image on the photosensitive drum 1.

The exposing means is performed through the following steps. The exposure unit 3 irradiates a light image on the photosensitive drum 1 by irradiating light based on image information read from an external device or the like, and includes a laser diode, a polygon mirror, a scanner motor, an imaging lens, and a reflection mirror. Is stored.

When an image signal is given from an external device or the like, the laser diode emits light according to the image signal and illuminates the polygon mirror as the image light. The polygon mirror is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror selectively exposes the surface of the photoconductor drum 1 through an imaging lens and a reflection mirror, and as a result, the image is formed on the photoconductor drum. Form an electrostatic latent image.

Simultaneously with the formation of the electrostatic latent image, the yellow developing cartridge 4Y is rotationally moved to the developing position and a predetermined bias voltage is applied to attach the yellow toner to the electrostatic latent image for development. After that, a bias voltage having a polarity opposite to that of the toner is applied to the pressing roller (primary transfer roller) 5j of the intermediate transfer belt 5a to primarily transfer the yellow toner image on the photosensitive drum 1 onto the intermediate transfer belt 5a.

When the primary transfer of the yellow toner image is completed as described above, the next developing cartridge is rotationally moved and positioned at a position facing the photosensitive drum. By repeating the above steps for each of magenta, cyan, and black colors, four color toner images are superimposed on the intermediate transfer belt 5a.

During this time, the secondary transfer roller 11 is not in contact with the intermediate transfer belt 5a. At this time, the cleaning charging roller 5f as a cleaning unit is also positioned in a non-contact state with the intermediate transfer belt 5a.

After the formation of the four color toner images on the intermediate transfer belt 5a, the secondary transfer roller 11 is pressed against the intermediate transfer belt 5a as shown in FIG. Further, in synchronism with the pressure contact of the secondary transfer roller 11, the transfer material, which has been waiting at a predetermined position near the registration roller pair 7 which is a feeding means, enters the nip portion between the intermediate transfer belt 5a and the secondary transfer roller 11. Sent out.

Here, immediately before the registration roller pair 7, there is provided a pre-registration sensor 14 which detects the leading end of the transfer material to shut off the rotational driving force of the registration roller pair 7 and makes the transfer material stand by at a predetermined position. ing.

A bias voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 11, so that the toner images on the intermediate transfer belt 5a are collectively transferred to the surface of the transferred transfer material.
Next is transcribed.

The transfer material to which the toner image is secondarily transferred is conveyed to the fixing means 8 via the conveying belt unit 12 and fixed, and is conveyed along the discharge guide 15 by the discharge roller pair 13 to the discharge roller. By the pair 9, the sheet is discharged to the discharge section 10 above the color image forming apparatus A, and the image formation is completed.

On the other hand, after the secondary transfer is completed, the cleaning charging roller 5f is pressed against the intermediate transfer belt 5a, and a predetermined bias voltage is applied to the surface of the intermediate transfer belt and the residual toner remaining after the secondary transfer to eliminate the residual charge.

The discharged residual toner is electrostatically retransferred from the intermediate transfer belt 5a to the photosensitive drum 1 through the primary transfer nip portion, and the surface of the intermediate transfer belt 5a is cleaned. The residual toner remaining after the secondary transfer retransferred to the photosensitive drum 1 is removed and collected by the cleaning blade 6 for the photosensitive drum 1.

The collected residual toner follows a conveyance route for conveying the waste toner, which will be described later, and a waste toner box.
Collected in 16 and accumulated.

(Developing Cartridge) Developing Cartridge 4
Is a developing device that visualizes the electrostatic latent image on the photoconductor drum 1. In the present embodiment, four developing cartridges capable of developing each color of yellow, magenta, cyan, and black. It is composed of 4Y, 4M, 4C and 4Bk.

As shown in FIG. 1, the developing cartridge 4 includes a rotary unit 301 which rotates about an axis.
Removably held by the mounting means formed on the
At the time of image formation, each developing cartridge 4 is rotationally moved about the shaft while being held by the rotary unit 301, and the predetermined developing cartridge 4 is stopped at a position facing the photosensitive drum 1, and further, a developing roller 305 described later. Is positioned so as to contact the photosensitive drum 1, and then a visible image is formed corresponding to the electrostatic latent image on the photosensitive drum 1.

During color image formation, the intermediate transfer belt 5
The rotary unit 301 rotates once for each rotation of a, and the developing process is performed in the order of the yellow developing cartridge 4Y, the magenta developing cartridge 4M, the cyan developing cartridge 4C, and then the black developing cartridge 4Bk.

FIG. 2 is a sectional view of the developing cartridge 4, and FIG. 3 is a perspective view thereof. In the developing cartridge 4, the toner in the developing container 302 forming the frame is sent to the toner supply roller 304 by the toner stirring means 303, and the toner supply roller 304 rotating clockwise in the drawing and the developing roller 305 are pressed against the outer circumference. A thin layer of toner is applied to the outer periphery of the developing roller 305 that rotates clockwise in the drawing by the blade 332.
In addition, the toner is charged (triboelectrically charged).

By applying a developing bias to the developing roller 305 facing the photosensitive drum 1 on which the latent image is formed, toner development is performed on the photosensitive drum 1 according to the latent image. Toner development is also performed on the magenta developing cartridge 4M, the cyan developing cartridge 4C, and the black developing cartridge 4Bk by the same mechanism as described above.

Further, each developing roller of each developing cartridge 4
305 is connected to a high-voltage power supply for each color development and a drive (not shown) provided in the printer main body when each development cartridge is rotationally moved to the development position, and a voltage is sequentially and selectively applied for each color development. And the drive is connected.

(Seal Structure of Developer Cartridge) Next, the seal structure of the developer cartridge 4 will be described in the order of attaching the seal member to the developer container.

FIG. 4 shows a state in which the developing container 302 is assembled to a state before the seal member is attached. Developer container
A toner supply roller 304 and a bush member 350 for sealing a concave portion provided for incorporating the toner supply roller 304 into the developing container 302 are attached to the toner supply roller 302 in advance.

FIG. 5A shows the developing blade 332 and the developing container 302.
Blade lower seal 351 which is a seal member filling the space
And a state in which an end seal 352, which is a seal member for filling a gap between the developing roller 305 and the developing container 302, is attached. The lower blade seal 351 is made of an elastic foam member and is attached to the developing container 302 with a double-sided tape (not shown). As shown in FIG. 5 (b), the end seal 352 has a surface layer on the surface of which is a raised layer 361 such as felt and an elastic foam layer 3 below the raised layer 361.
63, an adhesive layer 362 for sticking them between the raised layer 361 and the elastic foam layer 363, and an adhesive layer 364 such as a double-sided tape under the elastic foam layer 363, which is a total of four layers. The seal 352 is attached to the developing container 302.

Next, the structures of the developing blade 332 and the developing blade supporting plate (developing blade supporting member) 353 are shown in FIG.
Will be described using.

The developing blade 332 is made of stainless steel or phosphor bronze having a thickness of about 0.1 mm. The developing blade support plate 353 is made of a steel plate having a thickness of 1 to 2 mm. The developing blade 332 and the developing blade support plate 353 are positioned on a support base (not shown) through the positioning holes 354, and are joined by spot welding the points 355 of "*" shown in FIG. 6B.

FIG. 7 shows a state in which the developing blade 332 and the blowout preventing sheet 356 are attached to the developing container 302. In the developing blade 332, the positioning boss 357 of the developing container 302 is fitted into the positioning hole 354 of the developing blade 332 so that the developing container 302
And is fixed to the developing container 302. In addition, the blow-out prevention sheet 356 that fills the gap formed between the developing roller 305 and the developing container 302 is the sticking surface 3 of the developing container.
It is attached to 58 (see Fig. 2). Blowout prevention sheet
356 is an elastic sheet made of resin such as PET having a thickness of about 0.5 mm.

FIG. 8 shows a state in which the developing roller 305 is attached to the state where the developing cartridge 4 has been assembled up to this point.

Next, the structure of the seal member will be described. FIG. 9A shows the arrangement of the lower blade seal 351 and the end seal 352. Lower blade seal 351 and end seal 352
Is designed in advance so as to be arranged in the developing container 302 so as to invade at the overlapping portion indicated by 360 in FIG. 9A. To attach both seal members to the developing container 302, the lower blade seal 351 is first attached to the developing container 302, and then the end seal 352 is the developing container.
As shown in FIG. 9B, the end seal 352 is attached to the developing container 302 from above in a state where the overlap portion 360 of the lower blade seal 351 is laterally aligned in the direction of the arrow in the figure, as shown in FIG. 9B. Paste it on. When the lower blade seal 351 is released from the side-by-side state, the lower blade seal 351 and the end seal 352 are in close contact with each other on the side surface 390 and there is no gap, so it is possible to prevent toner from leaking from the joint portion of both seal members. You can

Next, the state where the developing blade 332 is arranged in the developing container 302 from the state where the above-mentioned seal member is attached is shown in FIG.
Shown in 10.

Here, the positions of the developing blade 332 and the developing blade supporting plate 353 are indicated by a chain double-dashed line. Figure 10 (a),
In FIG. 6B and FIG. 6C, the relationship between the tip positions of the developing blade 332 and the developing blade support plate 353 is β at the tip position of the developing blade 332 at both ends than at the tip position of the developing blade support plate 353. It has an extension area α extended by the distance of. In this area α, a chamfered portion 359 is provided on the developing blade supporting plate 353 in order to eliminate a step between the rear surface of the developing blade supporting plate 353 and the rear surface of the developing blade 332.

FIG. 10B shows a sectional view of the chamfered portion 359. Since the chamfered portion 359 is in contact with both the blade lower seal 351 and the end seal 352, and the sealing member comes into contact with the chamfered portion 359, the gap in this portion is surely suppressed, and the toner in this portion is prevented. Leakage can be prevented. The chamfered shape 359 can be formed by removing the corner portion of the developing blade supporting plate 353 by cutting or chamfering by pressing. Further, as shown in FIG. 10 (b), a developing blade support plate 35 formed by chamfering
It has been experimentally confirmed that if the flat portion 370 at the tip of 3 is 0.5 mm or less, the seal member comes into contact along this portion and the toner does not leak.

[Second Embodiment] FIG. 11 shows a second embodiment. In this case, the overlapping portion 360 of the lower blade seal 351 and the end seal 352 is located above the chamfer 359 of the developing blade support plate 353, and only the end seal 352 contacts the chamfer 359. However, the lower blade seal 351 is not in contact.

As described above, it is experimentally known that if the flat surface portion 370 of the developing blade supporting plate 353 is 0.5 mm or less, the sealing property can be secured.
In the chamfering process by the press, the larger the volume collapsed by the chamfering, the more the deformation is extended to other portions. Therefore, when the accuracy such as the flatness of the developing blade support plate 353 is emphasized, the flat surface portion 370 is 0.5 It may be larger than mm.

However, since the surface of the end seal 353 is the raised layer, toner leakage is relatively unlikely to occur even when the above-mentioned flat portion 370 is large, and the contact area between the chamfered portion 359 and the end seal 352 is large. By taking this, it is possible to sufficiently secure the toner sealing property of this portion.

[Other Embodiments] In the above-described embodiment, an example in which the developing device is used as a developing cartridge and which is attachable to and detachable from the main body of the image forming apparatus is shown. However, the above-mentioned sealing structure is effective because the toner sealing property can be improved.

[0058]

As described above, according to the present invention, the under-blade seal for sealing between the developing blade and the developing device frame is provided with the developing blade at the position where the developing blade is in pressure contact with the developing roller. It is possible to provide a developer sealing structure of a developing device that stably seals a gap in this portion without making contact with each other.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electrophotographic image forming apparatus.

FIG. 2 is a sectional view of a developing cartridge.

FIG. 3 is a perspective view of a developing cartridge.

FIG. 4 is a perspective view of a developing cartridge before a seal member is attached.

FIG. 5 is a diagram in which a seal member is attached to a developing cartridge.

FIG. 6 is a diagram showing a configuration of a developing blade.

FIG. 7 is a diagram in which a developing blade is attached to the developing cartridge.

FIG. 8 is a diagram in which a developing roller is arranged in a developing cartridge.

FIG. 9 is a diagram showing a sticking configuration of a seal member.

FIG. 10 is a diagram showing a positional relationship between a seal member and a developing blade.

FIG. 11 is an explanatory diagram of the second embodiment.

[Explanation of symbols]

A ... Color image forming apparatus 1 ... Photosensitive drum 2 ... Charging device 3 ... Exposure means 4 ... Development cartridge 4Bk ... Black developing cartridge 4C: Cyan developing cartridge 4M Magenta developer cartridge 4Y ... Yellow developing cartridge 5a ... Intermediate transfer member 5f ... Cleaning charging roller 5j ... Primary transfer roller 6 ... Cleaning blade 7 ... Registration roller pair 8 ... Fixing means 8a ... Pressure roller 8b ... Heating roller 9 ... Ejection roller pair 10… Ejection section 11… Secondary transfer roller 12… Conveyor belt unit 13… Ejection roller pair 14… Sensor before cash register 15… Discharge guide 16… Waste Toner Box 18… Pickup roller 19… Conveyor roller pair 301… Rotary unit 302 ... Development container 303 ... Toner stirring means 304 Toner supply roller 305 ... Developing roller 332 ... Development blade 350… Bush member 351… Seal under the blade 352… End seal 353 ... Development blade support plate 354… Positioning hole 355 ... point 356… Blowout prevention sheet 357… Positioning boss 358… Sticking surface 359… Chamfer 360… Overlap part 361… Brushed layer 362 ... Adhesive layer 363… Elastic foam layer 364 ... Adhesive layer 370… Flat section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasushi Yoshino             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2H077 AD06 AD13 AD17 AD23 BA08                       BA09 CA12 EA11 FA22 GA13

Claims (6)

[Claims] 1. A developing roller for developing a latent image formed on an electrophotographic photosensitive drum, and an elastic developing blade pressed against the developing roller to apply a thin layer of developer to the developing roller. A blade supporting member that is joined to the developing blade to reinforce the developing blade, a frame body that holds the developing roller, the developing blade and the blade supporting member, and a space between the blade supporting member and the frame body. An under-blade seal for filling the gap, and an extension in which the tip position of the developing blade is extended to the end portion in the longitudinal direction from the tip position of the blade supporting member at both longitudinal ends of the developing blade. An area, the blade supporting member has a chamfered portion with corners removed to eliminate a step between the developing blade surface and the developing blade surface, Developing apparatus is characterized in that at least the end seal seals in contact with the take part. 2. A chamfered portion, which has edge seals at both ends of the developing roller to fill and seal a gap between the developing roller and the frame, and has a corner portion of the developing blade supporting member removed. The developing device according to claim 1, wherein both the under-blade seal and the end seal are in contact with each other to seal. 3. The developing device according to claim 1, wherein the chamfered portion has a chamfered shape of a sheet metal member. 4. The width in which the tip of the chamfered portion is a flat surface is
The developing device according to claim 1, wherein the developing device has a thickness of 0.5 mm or less. 5. An image forming apparatus, which develops a latent image formed on an electrophotographic photosensitive drum and transfers the image to a recording medium to form an image, according to any one of claims 1 to 4. An electrophotographic image forming apparatus comprising: the developing device according to item 1; and a transporting unit that transports the recording medium. 6. The electronic device according to claim 5, wherein the developing device is attachable / detachable to / from the image forming apparatus main body, and has mounting means for detachably mounting the developing device to the image forming apparatus main body. Photo image forming apparatus.