JPH0631487Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a developing device used in, for example, an electrophotographic copying machine to develop an electrostatic latent image formed on a photoconductor with a toner.

(Prior Art) A developing device for developing an electrostatic latent image formed on a photoconductor with a toner usually has a developing roller disposed so as to face the photoconductor. The developing roller has a cylindrical developing sleeve and a magnet arranged in the developing sleeve. When the developing sleeve rotates, a developer composed of toner and carrier is formed on its peripheral surface. It is conveyed to the vicinity of the photoconductor by the brush. Then, a bristling portion is formed at the position where the developing sleeve and the photoconductor are opposed to each other, and only the toner of the developer on the developing sleeve adheres to the electrostatic latent image of the photoconductor, and the electrostatic latent image becomes the toner. It is developed.

In such a developing device, due to the centrifugal force of the rotation of the sleeve, the toner of the developer carried on the peripheral surface is scattered around. Since the triboelectric charge of the scattered toner is unstable with respect to the carrier, the scattered toner adheres to the photoconductor regardless of the electrostatic latent image on the photoconductor and causes background stains.
Further, when the scattered toner scatters around the photoconductor, there is a possibility that the charging device and the exposure device for forming an electrostatic latent image on the photoconductor are stained. When images are formed more frequently, the scattered toner accumulates on the developing device and its vicinity, and the accumulated scattered toner falls on the transfer paper transport path, causing local background stains. Therefore, various proposals have been made to prevent the scattered toner from leaking from the inside of the developing device so that the scattered toner does not adhere to the photoconductor, or to prevent the scattered toner from adhering and accumulating on the wall surface of the developing device.

Japanese Unexamined Patent Publication No. 60-69665 discloses a device for removing the toner adhering to the upper wall surface of the developing device. In this device, the toner adhering to the upper wall surface can be dropped, but at the time of this drop, the toner is scattered, and the scattered toner may adhere to the photoconductor. Further, the toner attached to the upper wall surface passes through the developing area (the contact portion between the drum and the developer) without being captured by the carrier because it is almost in an uncharged state. If this toner adheres to the drum or drops downward, it will cause background stains.

In Japanese Patent Laid-Open No. 59-21619, a floating plate is arranged along the peripheral surface of the developing sleeve for the purpose of suppressing the scattered toner. Since the floating plate covers the upper area of the developing sleeve over a wide area, the area of the developing sleeve in contact with the developer is large and the rotational resistance of the developing sleeve increases. Therefore, high torque is required to rotate the developing sleeve at a predetermined speed. When the floating plate comes into contact with the developer, the carrier itself may be separated from the developing sleeve and scattered. There is a possibility that scattered toner may accumulate on the upper surface of the floating plate.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and its object is to prevent scattered toner from leaking from the developing device and adhering to the photoconductor with a simple structure. It is to provide a developing device capable of preventing the above.

(Means for Solving Problems) In the developing device of the present invention, in order to develop the electrostatic latent image on the photoconductor with toner, the developer on the peripheral surface is supplied onto the photoconductor by the rotation thereof. A developing sleeve rotatably arranged facing the photoconductor, a spike cutting plate arranged to regulate the amount of the developer supplied onto the photoconductor by the developing sleeve, and a circumference of the developing sleeve. Magnetic means disposed within the developing sleeve to form a magnetic brush on the surface;
A lid that covers an area that is above the developing sleeve and that is on the downstream side of the spike cutting plate in the rotational direction of the developing sleeve and that faces the photoconductor; and a lid that scatters in the lid toward the photoconductor. To accommodate the developer flowing down along it, a toner reservoir is provided inside the lid on the downstream side in the developing sleeve rotation direction and below the photoconductor proximity position, and a base end portion is attached to the toner reservoir. The tip extends toward the downstream side in the rotational direction of the developing sleeve so that the tip comes into sliding contact with the developer of the developing sleeve at a position close to the rising portion of the magnetic brush in the developing area. And a flexible toner scattering prevention blade for sealing the developing sleeve above the area facing the photoconductor together with the lid, thereby achieving the above object.

(Embodiment) An embodiment of the present invention will be described below.

As shown in FIG. 1, the developing device 20 of the present invention is disposed in the vicinity of, for example, the photosensitive drum 10 disposed at the center of the electrophotographic copying machine. The photoconductor drum 10 has a photoconductor 11 on its outer peripheral surface and forms an electrostatic latent image on the photoconductor 11. The photoconductor drum 10 rotates in the direction indicated by arrow A.

The developing device 20 includes a developing roller 21 arranged to face the photoconductor drum 10 and an agitating roller 22 for supplying a developer to the developing roller 21. The developing roller 21 has a cylindrical developing sleeve 21a and a magnet body 21b fixedly arranged in the developing sleeve 21a. The developing sleeve 21a rotates in the forward direction (the direction indicated by the arrow B) with respect to the rotation direction of the photoconductor drum 10, and at the position closest to the photoconductor drum 10, the photoconductor 11 is rotated.
Toner development of the electrostatic latent image of. The magnet body 21b is, for example, 5
Has two magnets. Both poles of each magnet are developing sleeve 21
It is located in the radial direction of a. The polarity of the outer circumference of each magnet is
The polarities of the adjacent magnets are different from each other on the outer peripheral side.

The stirring roller 22 is arranged so as to face the developing roller 21, and rotates in the direction indicated by arrow C. Then, the toner supplied from the upper toner hopper 30 is mixed and agitated with the carrier by its rotation, the toner is frictionally charged, and the mixed and agitated developer is used as the developing sleeve 21a of the developing roller 21.
Supply to the peripheral surface.

A spike cutting plate 23 is arranged above the top of the developing roller 21. The bristle cutting plate 23 has a developing sleeve 21a at its lower end.
Is arranged so that it has a predetermined gap with the peripheral surface of
The developer conveyed on the peripheral surface of the developing sleeve 21a is regulated to a predetermined amount.

A lid body 24 is arranged downstream of the position of the bristle cutting plate 23 in the rotational direction of the developing sleeve 21a so as to cover the upper region thereof. The lid body 24 forms a predetermined space from the top of the developing sleeve 21a to the upper region on the downstream side of the developing sleeve 21a in the rotational direction, and covers the lid. The lower portion of the lid body 24 is located on the downstream side in the rotation direction of the developing sleeve 21a and substantially above the developing position of the developing sleeve 21a, and the lower portion bends into the space inside the lid body 24, and goes upward. A toner stay 24a that opens is formed. The bent end edge portion 24b of the lower portion of the lid forming the toner stay 24a is extended upward, and its extending direction is substantially the same as the tangential direction at the upstream position of the developing position of the developing sleeve 21a in the rotational direction. .

A base end of a toner scattering prevention blade 25 made of a flexible material is attached to the bent end edge 24b. The blade 25
Is extended downward from the bent edge portion 24b (toward the developing sleeve 21a side), and the tip end portion thereof is connected to the developing sleeve 21a.
Sliding on the conveyed developer on the peripheral surface of a.

The toner scattering prevention blade 25 may have flexibility, but is preferably insulative. As the blade, for example, urethane rubber having a thickness of 0.1 to 0.5 mm is used.

A fur brush seal 26 has a base end portion attached to the outer peripheral surface of the lid body 24. The tip of the fur brush seal 26 is in sliding contact with the outer peripheral surface of the photosensitive drum 10.

In the developing device 20 having such a configuration, the electrostatic latent image formed on the photoconductor 11 of the photoconductor drum 10 is toner-developed as in the conventional developing device. That is, the toner supplied from the hopper 30 is agitated with the carrier by the agitating roller 22 and frictionally charged, and together with the carrier, the developing sleeve of the developing roller 21.
21a is supplied to the outer peripheral surface. The developing sleeve 21a conveys the developer on the peripheral surface to the vicinity of the photoconductor drum 10 by its rotation. The developer conveyed on the developing sleeve 21a is
A magnetic brush is formed by the magnet body 21b in the developing sleeve 21a after the transport amount is regulated by the bristle cutting plate 23. In the magnetic brush, the spikes are formed by the magnets of the magnet body. The toner carried on the peripheral surface of the developing sleeve 21a is
As shown in FIG. 2, the photoconductor 11 is brought into contact with the ears of the developing region closest to the photoconductor 11, and the electrostatic latent image on the photoconductor 11 is developed with toner. The tip of the toner scattering prevention blade is in sliding contact with the developer at a position closest to the developing area.

During such rotation of the developing sleeve 21a, the toner of the developer that has passed through the spike cutting plate 23 may be scattered by the centrifugal force before it reaches the blade 25. After floating in the space covered by 24,
The toner is stored in the toner stay 24a. The toner scattering prevention blade is in sliding contact with the developer conveyed on the peripheral surface of the developing sleeve, and there is no possibility that scattered toner leaks to the photosensitive member side.

(Effect of the Invention) In the developing device of the present invention, since the toner scattering prevention blade is always in sliding contact with the developer on the peripheral surface of the developing sleeve, the scattered toner enters the developing area of the developing sleeve. There is no fear, and scattered toner, that is, toner with unstable triboelectric charging, does not adhere to the photoconductor. Therefore, there is no risk of background fogging on the image in the future.

In addition, in the developing device of the present invention, the toner scattered in the space inside the lid is stored in the toner reservoir, so that there is no possibility that toner will accumulate between the toner scattering prevention blade and the developer on the peripheral surface of the developing sleeve.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the developing device of the present invention, and FIG. 2 is an enlarged view of the main part thereof. 10 …… photosensitive drum, 11 …… photosensitive member, 20 …… developing device,
21 ... Developing roller, 21a ... Developing sleeve, 21b ... Magnetic body, 22 ... Stirring roller, 23 ... Spike plate, 24 ... Lid body,
24a: Toner stays, 25: Toner scattering prevention blade.

Claims (1)

[Scope of utility model registration request] 1. In order to develop the electrostatic latent image on the photoconductor with toner, the developer is rotatably arranged facing the photoconductor so that the developer on the peripheral surface is supplied onto the photoconductor by the rotation thereof. Developing sleeve, a spike cutting plate arranged to regulate the amount of developer supplied onto the photoconductor by the developing sleeve, and the developing sleeve so as to form a magnetic brush on the peripheral surface of the developing sleeve. A magnetic means disposed inside the cover, a lid for covering a region of the upper part of the developing sleeve facing the photoconductor in a downstream side portion of the ear cutting plate in the rotation direction of the developing sleeve, and the lid inside the photoconductor side. A toner reservoir arranged at the downstream side in the developing sleeve rotation direction inside the lid body and below the photoconductor so as to accommodate the developer that is scattered and flows down along the lid body; Attach the base end to the toner reservoir The tip extends toward the downstream side in the rotation direction of the developing sleeve so that the tip comes into sliding contact with the developer of the developing sleeve at a position close to the bristles of the magnetic brush in the developing area. ,
A developing device, comprising: a flexible toner scattering prevention blade that seals an upper part of the developing sleeve facing the photoconductor together with the lid.