JPH0635304A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a developer from leakage from both ends of a developer thin layer forming means (a cylindrical stick) provided on the developing device of an image forming device. CONSTITUTION:A developer leakage prevention unit 30 is embedded to a developing sleeve 26 attached to a developing device main body and both ends of the cylindrical stick 28 which is the developer thin layer forming means brought into a pressurized-contact to the sleeve. Furthermore, the developer leakage prevention means 30 is constituted of the developer leakage prevention member 31 where an upper curved surface 31a is slid into a pressurized-contact with the periphery surface of the developing sleeve 26 and a plane 32b on the right side is in a sliding contact with the left edge surface of the cylindrical stick 28 and an elastic member 32 stuck to it. The space between the developing sleeve 26 and the cylindrical stick 28 is sealed by the developer leakage prevention unit 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer leakage preventing means of a developing device installed in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Generally, an electrophotographic image forming apparatus such as a copying machine or a printer includes a platen on which a document is placed, a document irradiation lamp reciprocating below the platen, a reflection mirror, and a fixed projection lens and a reflection mirror. A configured scanning optics,
A photosensitive drum that is charged with a predetermined potential by a band electrode and rotates, a developing device that applies toner to an electrostatic latent image formed on the surface of the photosensitive drum by the scanning optical system to develop the electrostatic latent image, and the photosensitive drum. A transfer pole that transfers a toner image onto a recording sheet surface that is a transfer material that is conveyed toward the lower side of the body drum surface, a separation pole and a removing electrode, and fixes the toner image transferred onto the recording sheet surface. The fixing device is composed of a fixing device and a cleaning device for removing toner, paper dust and the like remaining on the surface of the photoconductor after transfer.

Then, desired toner images are successively recorded on the surface of the recording paper which is intermittently conveyed along a predetermined conveying path.

FIG. 4 shows a cross section of the main part of the developing device 6.
Is a main body of the developing device that forms the housing of the developing device 6, 22 is a first stirring member, 23 is a second stirring member, 24 is a supply roller, 26 is a developing sleeve, and 28 is developing applied to the peripheral surface of the developing sleeve 26. A cylindrical rod which is a developer thin film forming means having rigidity for regulating the amount of the developer, 28a is a spring plate for regulating the amount of the developer conveyed, and the cylindrical rod 28 has no developer on the developing sleeve 26. It is pressed with a constant load in the state. 27 is a scraper that cuts off the ears of the developer, 25 is a stirring partition plate,
Reference numeral 21 is an upper lid integrally attached to the upper surface of the developing device main body.

The toner replenished in the developing device 6 is sufficiently agitated and mixed with the carrier by the second stirring member 23 rotating in the direction of the arrow and the first stirring member 22 rotating so as to overlap each other in the opposite direction. The upper developer D is sent to the developing sleeve 26 via the supply roller 24.

The first stirring member 22 and the second stirring member 23 are screw-shaped members having a spiral angle of left-handed rotation in the opposite arrow directions, and are conveyed to the inner side by the thrust of the first stirring member 22. The toner and the carrier successively pass over the stirring partition plate 25 whose upper edge is slanted downward in the direction toward the back of the drawing, and the second
It moves to the side of the stirring member 23 and is conveyed to the front side of the drawing by its thrust, and becomes a homogeneous developer D that is triboelectrically charged by the mixing action of the toner and the carrier during that time, and is a sponge-like supply roller that rotates in the arrow direction The toner is adhered in a layered manner on the peripheral surface of the developing sleeve 26 which rotates clockwise by the arrow 24.

Then, the toner conveyed by the developing sleeve 26 is applied to the electrostatic latent image formed on the peripheral surface of the adjacent photosensitive drum 3 with a predetermined gap from the surface of the developing sleeve 26 to form a toner image. Is developed. The rotations of the first and second stirring members 22, 23, the supply roller 24, and the developing sleeve 26 are transmitted to each other by a drive transmission mechanism mounted on the side surface of the developing device main body 20.

The toner scattered in the image forming apparatus is sucked by a suction provided at a proper position.

[0009]

However, as shown in FIG. 4, a developer having a thickness of about 50 .mu.m is provided between the peripheral surface of the developing sleeve 26 and the peripheral surface of the cylindrical rod 28 which is a developer thin layer forming means. Due to the formation of the thin layer D, there is inevitably a gap on the outside in the left-right direction of this thin layer. Further, there is a gap between both side ends of the cylindrical rod 28 held by the developing device body 20 and the developing device body 20, and the toner separated from the developer D by the developing sleeve 26 rotating at high speed is developed from each gap. It leaks out of the vessel 6 and scatters. As a countermeasure against such a problem, conventionally, an elastic member such as a moltoprene material or rubber is embedded between both side ends of the cylindrical rod 28 and the developing device main body 20 in order to close the above-mentioned gaps. When a moltoprene material is used, it is sandwiched between the peripheral surface of the developing sleeve 26 and the peripheral surface of the cylindrical rod 28, and when a rubber material is used, slippage is poor, and the peripheral surface of the developing sleeve 26 and the cylindrical rod are used. A problem that the side end surface of 28 is pressed more than necessary, and in any case, the operation of the developing sleeve 26 or the cylindrical rod 28 is adversely affected and a predetermined thin developer layer is not formed on the peripheral surface of the developing sleeve 26. have.

The present invention solves the above problems and provides a developing device capable of preventing the developer from leaking from the vicinity of both side ends of the developer thin layer forming means (cylindrical rod) provided in the developing device. Is the task objective.

[0011]

[Means for Solving the Problems]
It is achieved by any means.

(A) In a developing device of an image forming apparatus for applying toner to an electrostatic latent image formed on an image bearing member to develop the electrostatic latent image, the developing device holds a peripheral surface of a developing sleeve held by the developing device main body. And a developer thin layer forming means for forming a thin layer of the developer on the peripheral surface of the developing sleeve by pressing against the developing sleeve, and one surface is provided between both side ends of the developer thin layer forming means and the developing device main body. A developer leakage preventing member, which is pressed against the peripheral surface of a developing sleeve and has the other surface slidingly contacting the side end surface of the developer thin layer forming means.

(B) A developing device as described in item (a), wherein the phases of both end portions of the developer thin layer forming means are matched with both end portions of the magnet of the developing sleeve.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side view showing the construction and arrangement of a developer leakage prevention member of FIG. 1, a front view of FIG. 2 and FIG.
4 will be described with reference to the side sectional view showing the configuration of the image forming apparatus and the side sectional view showing the main configuration of the conventional developing device in FIG.
However, the present invention is not limited to this embodiment. Each member of the developing device having the same function as the conventional one is represented by the same symbol.

Since the function and operation of the developing device 6 are exactly the same as those of the conventional device, the description thereof will be omitted and only the differences between the present invention and this invention will be described.

As shown in FIG. 3, an electrophotographic image forming apparatus 18 is provided.
A platen glass P for placing a document M is provided on the upper surface of the main body 1, and a scanning optical device 2 is provided below the platen glass P in the main body 1. The scanning optical device 2 includes a reciprocating document irradiation lamp 2a, a first mirror 2b, second and third mirrors 2c forming a V shape, a fixed lens 2d and a fourth mirror 2e. A photoconductor drum 3 is rotatably provided in the center of the inside of the main body 1 in the direction of the arrow, and in the periphery thereof, a belt electrode 4 for uniformly charging the photoconductor 3a along the rotation direction and a toner replenishing device. 5, a developing device 6 which is replenished with toner and has a developing sleeve 6a therein;
A transfer electrode 7, a separation electrode 8, a charge eliminating electrode 9, and a cleaning device 10 are sequentially arranged. Paper cassette 11,
Two types of recording papers of different sizes are housed in 11 'and set in the main body 1. 12 is a paper cassette 11
Is a first paper feed roller that feeds the recording paper stored in to a standby position before the second supply roller 13, and is a roller 12a that is rotated via a belt to prevent double feeding of the recording paper.
12a and a stop roller (also referred to as a separating roller) 12b. 13 is an appropriate timing so that the recording paper fed by the first paper feed roller 12 is temporarily stopped at the standby position, and then the leading edge of the visible image on the photoconductor 3a and the leading edge of the recording paper are aligned at the transfer position. The second paper feed roller 14 that feeds paper toward the transfer position again, and 14 is a guide plate for guiding the recording paper fed by the first paper feed roller 12 to the position of the second paper feed roller 13, It is opened and closed by operating a lever (not shown) so that the jammed paper can be taken out by inserting a hand. Reference numeral 15 is a conveying device that conveys the recording paper after transfer to a fixing position, and the fixing device 16 is a heating roller.
16a and pressure roller 16b. Reference numeral 17 denotes a paper discharge roller that discharges the recording paper after fixing to the outside of the main body.

When the copy button is operated in the above apparatus, the original M on the platen glass P is exposed and scanned by the scanning optical device 2, and an electrostatic latent image of the original M is formed on the photoconductor 3a of the photoconductor drum 3. It This electrostatic latent image is developed by the developing device 6.
Is converted into a visible image by the transfer electrode 7 and transferred to the recording paper fed from one of the paper feed cassettes 11 and 11 'of the main body 1. After the transfer, the recording sheet is separated from the photoconductor 3a by the separation electrode 8 and is fixed by the transport device 15.
The sheet is conveyed to 16, is fixed there, and is ejected by the ejection roller 17. In this way, desired toner images are successively recorded on the recording paper surface.

The developer leakage preventing members provided at both ends of the developer thin layer forming means (cylindrical rod) of the present invention are constructed and arranged as follows.

As shown in FIGS. 1 and 2, the developer leakage prevention unit 30 is composed of a developer leakage prevention member (hereinafter simply referred to as a leakage prevention member) 31 and an elastic member 32. The leakage prevention member 31 is a molded member made of, for example, a polyacetal resin having excellent lubricity, and its upper surface has an arc with a radius equal to the outer circumference circle of the developing sleeve 26 and a thickness t shown in FIG.
And a flat surface 31b having a curved surface 31a formed with a width d shown in FIG. 2 and the right side surface of FIG. 1 is in sliding contact with the left end surface of the cylindrical rod 28.
Are formed. The elastic member 32 attached to the leakage prevention member 31 is, for example, a member having elasticity made of urethane foam material, and the bottom surface portion which is the surface opposite to the curved surface 31a of the leakage prevention member 31 and the left surface which is the surface opposite to the flat surface portion 31b are previously formed. It is attached to the surface portion in an L-shape with double-sided tape or the like.

In this way, the leakage prevention member 31 is previously prepared.
Developer leakage prevention unit with elastic member 32 attached to the
Reference numeral 30 indicates a predetermined position of the developing device main body 20 such that the curved surface 31a of the leakage prevention member 31 faces the peripheral surface of the developing sleeve 26 and the flat surface portion 31b is in sliding contact with the left end surface of the cylindrical rod 28. insert. The developer leakage prevention unit 30 inserted and embedded in the developing device main body 20 is applied with a predetermined pressing force from the bottom surface direction indicated by the arrow to the peripheral surface of the developing sleeve 26 by the elastic force of the elastic member 32 attached in an L shape. From the direction of the left side surface which is pressed and is indicated by the arrow, it is slidably contacted toward the right side end surface of the cylindrical rod 28. Although illustration is omitted, the developer leakage prevention unit 30 similar to that described above is inserted and embedded in the left end surface of the cylindrical rod 28, the right end portion of the developing sleeve 26, and the developing device main body 20.

Therefore, the developer leakage prevention unit 30 provided symmetrically at two end portions on both sides of the cylindrical rod 28 causes a gap between the developing sleeve 26 and the cylindrical rod 28 pressed against the developing sleeve 26 and both end portions of the cylindrical rod 28. Since it is blocked, the developer D and the toner are prevented from leaking.

Since both ends of the magnetic range of the developing sleeve and both end faces of the cylindrical rod 28 are incorporated in the developing device main body 20 so as to coincide with the lines indicated by P to P ₁ , they are shown in FIG. The flat surface portion 31 b of the leakage prevention member 31 shown in FIG.
It is adapted to coincide with the left end of the thin layer of the developer D formed on the peripheral surface of. Therefore, the leakage prevention member 31 is embedded without a gap to further prevent the developer D and the toner from leaking. For the sake of accuracy, the position of the flat surface portion 31b of the leakage prevention member 31 is preferably within the magnetic range of the developing sleeve 26.

The leakage prevention member 31 molded of polyacetal resin having an extremely high lubricity comes into sliding contact with the peripheral surface of the developing sleeve 26 and both end surfaces of the cylindrical rod 28 at a predetermined pressing force to operate. Therefore, it operates extremely smoothly without affecting the rotation of the developing sleeve 26 and the operation of the cylindrical rod 28. In this way, the developer D and the toner are prevented from leaking from both side ends of the cylindrical rod 28, so that a good toner image is always developed on the peripheral surface of the photosensitive drum 3. Although the present invention has been described by taking the developing device of the mono-black image forming apparatus as an example, it goes without saying that the present invention is also applied to the developing device of the color image forming apparatus.

[0024]

EFFECT OF THE INVENTION Developer thin layer forming means (cylindrical rod) of the present invention
Since a developer leakage prevention unit that acts on both end faces of the developing sleeve and the peripheral surface of the developing sleeve is provided, the leakage of the developer into the image forming apparatus is prevented and the operation of the developing sleeve and the columnar rod is not affected, resulting in extremely smooth Can operate.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the configuration and arrangement of a developer leakage prevention member according to an embodiment of the present invention.

FIG. 2 is a front view of the above.

FIG. 3 is a side sectional view showing the configuration of the image forming apparatus.

FIG. 4 is a side sectional view showing a main configuration of a conventional developing device.

[Explanation of symbols]

 3 Photoreceptor Drum 6 Developing Device 18 Image Forming Device 20 Developing Device Main Body 26 Developing Sleeve 30 Developer Leakage Prevention Unit 31 Developer Leakage Prevention Member 31a Curved Surface 31b Flat Surface 32 Elastic Member D Developer

Claims (2)

[Claims] 1. A developing device of an image forming apparatus for applying a toner to an electrostatic latent image formed on an image bearing member to develop the electrostatic latent image, the developing device being held by a developing device main body and provided on a peripheral surface of a developing sleeve. A developing agent thin layer forming means for pressing and forming a developing agent thin layer on the peripheral surface of the developing sleeve is provided, and one surface is developed between both side ends of the developing agent thin layer forming means and the developing device main body. A developer leak preventing member, which is pressed against the peripheral surface of the sleeve and has the other surface slidably contacting the side end surface of the developer thin layer forming means. 2. A developing device according to claim 1, wherein the phases of both end portions of the developer thin layer forming means are matched with both end portions of the magnet of the developing sleeve.