JPH08314267A - Developing device - Google Patents

Abstract

PURPOSE: To prevent toner scattering so as to prevent the internal part of a product from getting dirty or an image from being soiled by scattered toner by providing a member having elasticity and having small frictional resistance in a gap between a developing roller and a bristle cutting blade out of a range corresponding to an image forming area. CONSTITUTION: Developer held on the surface of the developing roller 25a is carried white it is bristle-cut to be in specified thickness by the bristle-cutting blade 25d. The blade 25d is adjusted to form a specified gap with the roller 25a and screwed. A toner scattering preventing seal 28 having the elasticity and having the small frictional resistance is provided in the gap out of the image forming area between the blade 25d and the roller 25a. The seal 28 is fixed in contact with the roller 25a in a state where it is compressed and deformed as the blade 25d is fixed by screwing to fix the blade 25d.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an electrophotographic apparatus, such as an optical printer or a copying machine, which uses electrophotographic technology, and in particular, it prevents toner scattering and reduces print quality due to toner drop due to scattered toner. It relates to the means to prevent.

[0002]

2. Description of the Related Art In order to form a stable image, it is necessary to make the contact between the developer and the photosensitive member uniform, and conventionally, there has been a means for controlling the height of the developer on the surface of the developing roller by a cutting blade. Has been taken. Also, due to the miniaturization of the device,
As in Japanese Patent Laid-Open No. 7-49610, there is proposed a method of forming a spike cutting blade on a plate.

[0003]

However, in order to form a stable image in the entire image area, the above-mentioned prior art restricts the developer height in a wider range than the area corresponding to the image forming area. It is necessary to provide a gap between the spike-cutting blade and the developing roller, but outside this image area, the formation of the developing brush is not stabilized, and in order to stabilize it, the area is wider than the necessary image area. Since the gap is provided, the toner is scattered from the gap between the spike cutting blade and the developing roller. In this way,
There is a problem that the toner scattered from the developing device stains the inside of products such as printers and copying machines, and eventually the toner accumulated inside the device falls and stains the image.

The object of the present invention is to prevent toner scattered from the gap between the spike-cutting blade and the developing roller outside the image forming area, and to stain the inside of products such as printers and copiers, and stain the image with scattered toner. In order to prevent the occurrence of a clear image.

[0005]

The above object is achieved by providing a member having flexibility and a small frictional resistance in the gap between the developing roller and the cutting blade outside the range corresponding to the image forming area. it can.

A member having flexibility and a small frictional resistance, which is provided in the gap between the developing roller and the cutting blade, can be achieved by using a member which is easily plastically deformed. Further, the member having flexibility and having a small frictional resistance, which is provided in the gap between the developing roller and the bristle cutting blade, can be achieved by providing it at a position which is always in contact with the developing brush formed on the developing roller.

Further, the flexible member provided in the gap between the developing roller and the cutting blade and having a small frictional resistance is provided for regulating the height of the developer held on the developing roller. This can be achieved by compressing and plastically deforming with the cutting blade and fixing it in the gap between the developing roller and the spike cutting blade.

[0008]

In the developing device of the present invention, a member which has flexibility, has a small frictional resistance, and is plastically deformed is provided in the gap between the developing roller and the cutting blade outside the image forming area. Due to the added flexibility, it adheres to both the developing roller and the edge-cutting blade, and without forming an extra gap, it is possible to provide a gap only for the part necessary for image formation. It is possible to prevent the toner from being scattered. Further, since this member has a low frictional resistance with the developing roller, it does not hinder the rotational driving of the developing roller and has no adverse effect on the image quality. In addition, since a member having such a small frictional resistance generally has low adhesiveness, its fixing method is often a problem.
By using the plastically deformable member, a member thicker than the gap between the developing roller and the spike-cutting blade can be fixed at the same time by fixing the developing roller and the spike-cutting blade and compressing and plastically deforming the member. As such a member, a porous fluororesin can be used. By using a fluororesin, the frictional resistance is reduced, and since it is porous, it is possible to compress the voids inside the member, and as a result, a member that is flexible and can be easily plastically deformed is used. You can get it.

Further, when a sealing material for preventing toner scattering is provided in the gap between the developing roller and the cutting blade, the toner adheres to and accumulates on the side surface of the sealing material, and the accumulated toner eventually falls. The problem of smearing the image occurs.This is because the member provided in the gap between the developing roller and the edge-cutting blade is always in contact with the developing brush formed on the developing roller, so that the developing brush scratches the adhered toner. Since the toner is collected and collected, the problem that the toner adheres to the sealing material can be prevented.

[0010]

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

FIG. 6 is a vertical cross-sectional view of a color laser printer to which the present invention is applied, in which a photosensitive belt 2 is stretched around rotating rollers 3, 4 and 5 at the center of the printer body 1 to rotate. It is held freely. The rotating roller 3 for driving the belt rotates so as to convey the photosensitive belt at a speed of about 70 mm / s. The rotating rollers 3 and 4 are arranged so as to form a flat developing area on the photosensitive belt.
5 is arranged so as to form a toner image transfer area described later. Further, the rotating roller 3 guides the photosensitive belt 2 so as to form a stable exposure surface for the scanning exposure described later on the photosensitive belt 2.

A charger 6 for corona discharge, a laser beam scanning exposure unit 7, and a belt cleaner 16 are arranged below the photosensitive belt 2. The laser beam 7a generated from the scanning exposure unit 7 under the control of the video signal given from the higher-order image signal generator is a photosensitive member in the direction crossing the surface of the photosensitive belt 2 which rotates along the surface of the rotating roller 3. The surface of the belt 2 is scanned and exposed to form an electrostatic latent image in the rotating direction of the photosensitive belt 2.

On the upper side of the photoconductor belt 2, developing devices 8 to 11 are removably arranged so as to oppose the developing region in which the photoconductor belt 2 rotates flat, and the developing devices 8 to 11 are detachably arranged.
The surface of the photoconductor belt 2 is rubbed with the developer magnetic brush formed in 1. to develop the electrostatic latent image. The developing device 8 uses a developer containing yellow (Y) toner, and the developing device 9
A developer containing magenta (M) color toner is used for the developing device 10, a developer containing cyan (C) color toner is used for the developing device 10, and a black (K) color developer is used for the developing device 11. A developer containing toner is used. Then, these developing devices 8 to 11 are selectively acted on the photoconductor belt 2 in accordance with the corresponding color of the electrostatic latent image to develop each electrostatic latent image into a toner image of a corresponding color. In order to develop each electrostatic latent image, one developing device 8 (9 to 11) is selected and acts on the photosensitive belt 2 for about 5 seconds.

The intermediate transfer drum 12 is arranged so as to rotate while contacting the photosensitive belt 2 positioned in the printer body 1 in the toner image transfer area.
The toner image formed on the surface of is transferred in this toner image transfer area. The intermediate transfer drum 12 is rotated by the rotational drive of the photoconductor belt 2 in contact therewith. Around the intermediate transfer drum 12, a pre-charger 13, a transfer roller 14, and a drum cleaner 15 are arranged so as to face the outer peripheral surface of the intermediate transfer drum 12, and toner images of respective colors are superposed on the outer peripheral surface from the photosensitive belt 2. The images are sequentially transferred to form a color toner image.

The precharger 13 is a corona discharger,
A corona discharge is generated by being urged to give a charge for supporting the transfer of the completed color toner image onto the recording paper 17 on the surface of the intermediate transfer drum 12. Drum cleaner 15
Is movable toward and away from the surface of the intermediate transfer drum 12, and in the process of forming a color toner image by transferring a plurality of single-color toner images from the photosensitive belt 2 onto the intermediate transfer drum 12 in a superimposed manner, the outer peripheral surface After the color toner image completed on the outer peripheral surface is transferred to the recording paper 17, it is operated so as to come into contact with the surface of the intermediate transfer drum 12.

The paper feed mechanism is arranged in a space below the scanning exposure unit 7, and the recording paper 1 stored in the paper feed cassette 18 is provided.
7 is extracted by the paper feed roller 19 and sent out. A registration roller 20 that aligns the color toner image formed on the surface of the intermediate transfer drum 12 and the conveyance timing of the recording paper 17 onto which the toner image is transferred is provided between the paper feed roller 19 and the transfer roller 14, and is a paper feed roller. The recording paper 17 sent from 19 is sent to the transfer roller 14 with the conveyance timing adjusted. The registration roller 20 is the recording paper 17
At about 70 mm / s (the same speed as the photosensitive belt 2). A transport guide 21, a fixing device 22, and a paper discharge roller 23 are provided downstream of the transfer roller 14, and a paper discharge tray 24 on which a printed matter (recording paper 17 with toner fixed) sent from the paper discharge roller 23 is placed. Are formed on the upper surface of the printer body 1. Next, details of the developing devices 8 to 11 will be described. Since the four developing devices 8 to 11 have basically the same configuration, the developing device 8 will be described as an example.
FIG. 2 shows a state in which the constituent parts of the developing device 8 are separated.

The developing frame 25e of the developing unit 25 is a non-replaceable component fixed to the printer body, and includes a developing roller 25a and a conveying roller 25b which are arranged to face the photosensitive belt 2 with a predetermined developing gap. Prepare,
A brush cutting blade 25d formed of a non-magnetic material that defines the height of a developing brush formed by the developer 26k held on the surface of the developing roller 25a, and a developer transferred from the developing roller 25a to the conveying roller 25b. 26k transport roller 2
Peeling blade 25 made of non-magnetic material for peeling from 5b
c.

The developing cartridge 26 is a developing unit 25.
In the new state, a new developer 26k is stored in the developer container 26p, and the lower surface of the developer container 26p is closed by a seal that can be peeled off by pulling out from the lateral direction. Has been. The developer container 26p is provided so that the developer does not spill when the developer cartridge 26 is transported, and the developer container 26p can simplify the packing means of the developer cartridge 26. The toner cartridge 27 is a replacement part that fits in the developing cartridge 26, and the lower surface of the new state is closed by a seal that can be peeled off by pulling out from the lateral direction. Inside the toner cartridge 27, there are a toner replenishing roller 27 a and a toner stirring blade 27 b.
Is provided with an engagement stopper 27c for fitting and fixing at a predetermined position of the developing cartridge 26, and the toner replenishing roller 27a rotates when the toner concentration of the developer 26k in the developing cartridge 26 becomes lower than the predetermined concentration. Then, the toner 27d is replenished in the developing cartridge 26.

In this developing device, as shown in FIG. 3, a developing cartridge 26 is attached to the developing unit 25, fixed at a predetermined position by an engaging lever 26j, and a toner cartridge 27 is attached to the developing cartridge 26. The toner lever 27 pushes down the shutter lever 26e of the developing cartridge 26 in a direction in which the shutter lever 26e rotates about a fulcrum while the fixing stopper 27c fixes the developer supplying port 26c. It moves around the fulcrum to the open position, and the developing operation is possible in this state. The developing shutter 26d is normally pressed by a force that closes the developer supply port 26c by a reaction force of a spring. Therefore, when the shutter lever 26e cannot be pushed down by the toner cartridge 27, the developing shutter 26d always closes the developer supply port 26c.

Further, as shown in FIG. 5, when the toner cartridge 27 is mounted on the developing cartridge 26 mounted on the developing unit 25, the engagement lever 26j of the developing cartridge 26 cannot be released.

That is, the toner cartridge 27 is pulled out, whereby the force of pushing down the shutter lever 26e of the developing cartridge 26 is released, and the developing shutter 26 is released.
The developing shutter 2 by the reaction force of the spring attached to d.
6d closes the developer supply port 26c, and the developing cartridge 26 is pulled out in this state.

Although illustration is omitted, when the number of printed sheets reaches the end of the life of the developer, the operation panel of the printer body 1 is informed of the replacement of the developer, and the operation of replacing the developer is performed. The toner cartridge 27 is replaced with the developing cartridge 2
6, the developer supply port 26c of the developing cartridge 26 is closed by the developing shutter 26d.
It is possible to replace the developer without spilling even in the work of extracting the developer. Also, a new developer cartridge 2
By mounting 6 on the developing unit 25 and peeling off the seal blocking the lower surface of the developer container 26p, new developer can be supplied to the developing cartridge 26, so that the developer can be replaced easily.

The developing unit 25 is the most expensive component that needs to be maintained with high precision in the developing device. However, if the developing cartridge 26 is replaced as described above, the developing unit 25 is permanently installed. Can be installed and used.

The operating condition of this developing device is shown in FIG. The developer 26k in the developing cartridge 26 is a mixture of a magnetic carrier and an insulating toner. The stirring screw 26b uniformly mixes and stirs the carrier and the toner, and the stirring supply roller 26a from the developer supply port 26c into the developing unit 25. Is supplied to the developing roller 25a. The developing roller 25a is driven before the stirring and supplying roller 26a rotates, and the developer 26k held on the surface thereof by the magnetic force of the developing roller 25a has a predetermined thickness by the spike cutting blade 25d. While being cut off, it is conveyed in the direction of arrow A and rubs against the photoconductor belt 2 to develop the electrostatic latent image formed on the surface of the photoconductor belt 2.

The developer 26k which has passed through the developing area is transferred from the developing roller 25a to the carrying roller 25b and carried to the upper part of the developing unit 25, and is peeled off from the carrying roller 25b by the peeling blade 25c and falls, so that the developing cartridge 26 And is collected in the developing cartridge 26. Also, the guide base 26i
Part of the developer 26k guided to the inside flows into the toner concentration detecting container 26n, and by the toner concentration detecting element 26f,
The toner density of the developer 26k is converted into a voltage and is constantly detected. The voltage change detected by the toner concentration detecting element 26f with respect to the toner concentration of 1% of the developer 26k is 0.5 V, and when the toner concentration of the developer 26k is low, the voltage detected by the toner concentration detecting element 26f becomes high. If the toner concentration is high, the voltage will be low. That is, when the voltage detected by the toner concentration detecting element 26f is higher than the predetermined voltage, the toner replenishing roller 2 in the toner cartridge 27 is
7a is rotated and the toner 27d is supplied to the developing cartridge 26.
Supply to.

When the developing process in the developing device 8 is completed, the rotation of the stirring and feeding roller 26a is stopped, and the developer 2
Although the supply of 6k to the developing roller 25a is stopped, the developing roller 25a conveys the developer 26k already supplied to the upper portion of the spike-cutting blade 25d, and therefore, the rotation continues for 2 seconds even after the stirring and supplying roller 26a is stopped. The developer collecting operation is performed so that the developer 26k does not exist in the portion of the developing roller 25a facing the photosensitive belt 2. By this developer collecting operation, the toner images formed on the other developing devices 9 to 11 on the photosensitive belt 2 are not disturbed.

FIG. 1 shows a bottom view of the developing device 8, a partial view of an AA vertical cross section shown in the drawing, and an enlarged view of a portion B thereof.

The cutting blade 25d is a developing roller 25a.
And it is adjusted so that a predetermined gap is provided and screwed. This ear cutting blade 25d and developing roller 25a
There is flexibility in the gap outside the image forming area of
Further, a toner scattering prevention seal 28, which is a member having a small frictional resistance, is provided. As shown in the partial view of the AA cross section,
The toner scattering prevention seal 28 is in contact with the developing roller 25a in a state of being compressed and deformed by fixing the spike cutting blade 25d with a screw for fixing the spike cutting blade 25d,
Fixed.

In this embodiment, a porous fluororesin is used as the member of the toner scattering prevention seal 28, and polytetrafluoroethylene having a small friction coefficient is used among the fluororesins. A fluororesin such as vinylidene, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene-6-fluoropropylene copolymer, or the like can be used, but is not limited thereto.

Further, as a member having a small frictional resistance with the developing roller, a soft material whose surface is coated with these fluororesins can be used. Further, as another method, it is effective to coat the surface of the developing roller 25a with a fluororesin. As described above, since the toner scattering prevention seal 28 reduces the frictional resistance with the developing roller 25a, it does not have any influence on the rotation of the developing roller 25a and has flexibility. It is possible to prevent the toner from scattering by sealing the gap between the developing roller 25a and the spike cutting blade 25d without any gap. Further, the porous fluororesin used in this example has an internal pore size of 0.5 μm or less, which is sufficiently smaller than the toner size of about 10 μm used in this example. There is no adverse effect such as toner clogging.

Further, the toner scattering prevention seal 28 is provided at a position corresponding to the outside of the image forming area. However, the developing brush formed by the developer 26k held on the surface of the developing roll 25a is the toner scattering prevention seal. It is formed to a position where it always contacts 28 (not shown). That is, the developing brush formed of the developer 26k held on the surface of the developing roller 25a is always held and conveyed on the surface of the developing roller 25a during the developing operation, and the toner scattering prevention seal 2
Since the side surface of 8 is rubbed, the toner does not adhere to and accumulate on the side surface of the toner scattering prevention seal 28.

[0032]

According to the present invention, by reducing the frictional resistance between the toner scattering prevention seal 28 and the developing roller 25a, there is no effect on the rotation of the developing roller 25a, and the toner scattering is prevented. Since the prevention seal 28 has flexibility, the developing roller 25a and the cutting blade 25d
It is possible to prevent the toner from scattering by sealing the gap without gap. As a result, it is possible to prevent the toner scattered from the gap between the spike cutting blade 25d and the developing roller 25a without adversely affecting the image quality. It is possible to prevent the image from becoming dirty and form a beautiful image. Further, the developing brush formed of the developer 26k held on the surface of the developing roller 25a always rubs the side surface of the toner scattering prevention seal 28 while being held and conveyed on the surface of the developing roller 25a during the developing operation. The toner does not adhere to and accumulate on the side surface of the toner scattering prevention seal 28, and the accumulated toner does not drop and stain the image.

[Brief description of drawings]

FIG. 1 is a bottom view of a developing device according to the present invention and a partial vertical sectional view thereof.

FIG. 2 is a vertical cross-sectional side view of the developing device according to the present invention with its constituent parts separated.

FIG. 3 is a vertical cross-sectional side view showing a state in which a developing cartridge and a toner cartridge are attached to a developing unit in the developing device according to the present invention.

FIG. 4 is a vertical cross-sectional side view showing an operating state of the developing device according to the present invention.

FIG. 5 is a perspective view showing a state where a developing cartridge and a toner cartridge are attached to a developing unit in the developing device according to the present invention.

FIG. 6 is a vertical sectional side view of a color laser printer to which the developing device according to the present invention is applied.

[Explanation of symbols]

2 ... Photosensitive belt, 8-11 ... Developing device, 25 ... Developing unit, 25a ... Developing roller, 25d ... Spike blade, 26 ... Developing cartridge, 26a ... Agitation supply roller, 26c ... Developer supply port, 26d ... Development shutter,
26e ... Shutter lever, 26f ... Toner concentration detecting element, 26n ... Toner concentration detecting container, 26j ... Engaging lever, 27 ... Toner cartridge, 27c ... Engaging stopper, 28 ... Toner scattering preventing seal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tomio Hayano Inventor Tomio Hayano 1-1-1 Higashitaga-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Electric Appliances Division, Taga Headquarters (72) Inventor Katsumi Mikami Hitachi, Ibaraki 1-1-1, Higashitaga-cho, Higashi-shi Incorporated company Hitachi, Ltd.

Claims (5)

[Claims] 1. A developing roller for holding a developer supplied from a developer replenishing port of a developing cartridge on its surface to act on an electrostatic latent image surface, and a height of the developer held by the developing roller. In a developing device having a controlling ear cutting blade, a member having flexibility and small frictional resistance is provided in a gap between the developing roller and the ear cutting blade outside a range corresponding to an image forming area. Developing device. 2. The developing device according to claim 1, wherein the member is a member that is easily plastically deformed. 3. The developing device according to claim 1, wherein the member is a porous fluororesin. 4. The developing device according to claim 1, wherein the member is provided at a position which is always in contact with a developing brush formed on the developing roller. 5. The developing roller and the spike-cutting blade according to claim 2, wherein the member is compressed and plastically deformed by a spike-cutting blade provided to regulate the height of the developer held by the developing roller. A developing device, which is fixed in the gap of the.