JPH0521262U - Developing device for electrophotographic device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a magnetic brush type developing device, to prevent the developer from falling from the developing device and the toner cloud from leaking out. A first developer leakage prevention member is provided at a lower end portion of an opening of a developing casing so that the tip is close to the surface of the photoconductor, and the tip is further provided below the first leakage prevention member. The second leakage prevention member is disposed so as to be positioned toward the photoconductor side with respect to a perpendicular line passing through the tip of the first leakage prevention member.
Provide a leak prevention member. The second leakage prevention member is the first
Has a receiving portion for receiving the developer falling from the leakage prevention member.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a developing device for an electrophotographic apparatus, and more particularly, to a developing device having means for preventing a developer from falling through an opening of a casing of the developing device and a toner cloud from leaking.

[0002]

[Prior Art]

 A magnetic brush developing device is often used as a developing device for an electrophotographic apparatus such as a copying machine or a printer. A magnetic brush developing device magnetically adsorbs a one-component or two-component developer on a rotating developing sleeve to form a developer brush, and the brush is rubbed against the surface of the photoreceptor to make it contact the photoreceptor. The formed electrostatic image is developed.

In such a developing process, when the developer brush comes into contact with the photoconductor, some of the developer is detached from the surface of the sleeve and falls, or becomes a toner cloud, and is discharged from the casing opening to the outside of the developing device. It may leak, pollute the inside of the electrophotographic device, or cause a malfunction. For this reason, in the prior art, a leakage prevention member is provided at the lower end of the casing opening in the vicinity of the surface of the photosensitive member and extends axially along the surface of the photosensitive member so as to receive the developer dropped from the sleeve. This prevents leakage of the product to the outside of the device.

[0004]

[Problems to be solved by the device]

 However, even with such means, it was not possible to satisfactorily achieve the complete leakage prevention and drop prevention of the developer.

Therefore, an object of the present invention is to provide a developing device having a simple structure, which completely prevents the developer from leaking from the developing device and prevents the contamination of the developer in the electrophotographic apparatus. With the goal.

[0006]

[Means for Solving the Problems]

 The present invention has been made in view of the above problems, and provides an electrophotographic apparatus including a casing having an opening facing a surface of a photoconductor and a developing sleeve disposed in the casing and supplying a developer to the photoconductor. In the developing device, a first developer leakage prevention member which is arranged at a lower end portion of the opening so that a tip thereof is close to the surface of the photoconductor, and which prevents the developer from falling from the opening; A developer that is arranged below the leak prevention member so that its tip is positioned toward the photoconductor side with respect to a perpendicular line passing through the tip of the first leak prevention member and falls from the first leak prevention member. It is characterized by having a second leakage prevention member having a receiving portion for receiving.

[0007]

[Action]

 According to such means, the developer which is about to leak from the sleeve opening is prevented from leaking by the first leak prevention member. Most of the developer is guided by the receiving portion of the first leakage prevention member and returned to the inside of the sleeve, for example, but some of the developer is deposited on the tip portion of the first leakage prevention member. The accumulated developer gradually becomes a lump and separates from the first leakage prevention member and falls. The second leak prevention member receives the dropped developer by its receiving portion, and reliably prevents the developer from leaking out of the developing device.

[0008]

【Example】

 Hereinafter, the developing device according to the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a photosensitive drum having an electrophotographic photosensitive member on its surface, which rotates in a direction indicated by an arrow A when actuated by a driving device (not shown). Corona charging device 2 that uniformly charges the surface of the photoconductor to a specific polarity along the periphery of the photoconductor drum 1 according to the rotating direction of the photoconductor drum 1, and projects an optical image on the charged surface of the photoconductor to form an electrostatic latent image. , An image exposure device 3 for forming an electrostatic latent image, a developing device 10 for developing an electrostatic latent image into a visible toner image, and a charge opposite in polarity to the toner image is applied from the back side of the transfer paper fed by the timing roller 4. Then, the transfer corona discharger 5 that transfers the toner image on the photoconductor drum onto the transfer paper, the AC corona separation device 6 that neutralizes and separates the transfer paper after transfer from the surface of the photoconductor, and the separated transfer paper is next. A conveyor belt 7 for conveying to a sequential fixing device, a cleaning device 8 for cleaning the developer remaining after the transfer, and a static eliminator 9 for uniformly exposing the surface of the photoreceptor after cleaning to eliminate the charge are arranged.

The developing device 10 is roughly divided into a casing 11 for storing a developer therein, a developing sleeve 12 arranged in the casing 11, and a toner supply device 13 for supplying toner into the casing. . For simplicity of the drawing, the developer is not shown. The image sleeve 12 is a non-magnetic rotatable sleeve that rotates in the direction indicated by arrow B when actuated. On the surface of the sleeve 12, the developer is adsorbed by the magnetic force of the magnet device 14 fixedly arranged in the sleeve 12 to form a developer brush (magnetic brush). Reference numeral 15 is a doctor blade for controlling the height of the brush of the developer brush, 16 is a scraping blade for removing the developer on the sleeve 12 that did not contribute to the development, and 17 is a stirring member for stirring the developer in the casing 11. Indicates.

The casing 11 forms an opening 111 facing the photoconductor drum 1, and a part of the peripheral surface of the developing sleeve 12 faces the photoconductor drum 1 with a predetermined gap from the opening 111. As a result, the developer brush formed on the sleeve 12 rubs the surface of the photosensitive drum 12 to develop the electrostatic image.

At the lower end of the opening 111 of the casing 11, the first developer leakage prevention member 20 is fixed to the bottom of the casing 11 so that the tip of the opening 111 approaches the surface of the photosensitive drum 1. The first developer leakage prevention member 20 is composed of a plate-shaped member extending over the entire width of the opening 111, and its tip is separated from the surface of the photosensitive drum 111 by several mm (for example, 1 to 3 mm). An elastic body such as rubber or a flexible, preferably porous member 21 such as sponge or felt is provided in the interior of the container. Such a member 21 functions to prevent damage to the photoreceptor due to contact that may occur when the developing device is attached or detached. The first developer leakage prevention member 20 is inclined so as to descend in the direction away from the photosensitive drum 1, and the developer released from the sleeve 12 is received by the receiving portion 22 and guided inside the casing 11.

As particularly shown in FIG. 2, the tip b of the member 21 is located closer to the photosensitive drum than a perpendicular line a passing through the developing position of the photosensitive drum 1 (a position facing the current image sleeve 12). This is important for appropriately preventing the developer from falling from the opening 111.

Below the first leakage prevention member 20, a second leakage prevention member 30 is arranged with its rear end fixed to the bottom portion of the casing 11. In the illustrated example, the prevention members 20 and 30 are fixed to the casing 11 by a common fastener such as a screw. The member 30 is a plate member having a substantially L-shaped cross section and extends over the entire width of the opening 111. Similar to the first leakage prevention member 20, the tip of the second leakage prevention member 30 is separated from the surface of the photosensitive drum 111 by a few mm (for example, 1 to 3 mm) by an elastic body such as rubber or a sponge or felt. A flexible, preferably porous member 31 such as The tip c of the member 31 is located toward the photoconductor side with respect to the perpendicular line passing through the tip b of the first leakage prevention member, and as a result, the developer is temporarily dropped from the tip b of the first leakage prevention member 20. Even so, it is prevented from falling out of the developing device. The developer received by the second leakage prevention member 30 is stored in the receiving portion 32. The accumulated developer is discarded by removing the prevention member 30 at the time of maintenance of the apparatus.

The tip members 21 and 31 of the first leakage prevention member 20 and the second leakage prevention member 30, respectively, serve to prevent the damage of the photoconductor as described above, and the toner cloud from the developing device. Acts to prevent the leakage of. The toner cloud that tries to leak through the gap between the opening 111 of the developing device 1 and the photoconductor drum 1 is blocked by the members 21 and 31 and is prevented from leaking to the outside. Particularly in the case of a porous member, fine toner particles are captured by the fine pores of this member, and leakage to the outside is further prevented. Further, by arranging the member 31 so as to be in contact with or close to the upper wall 41 of the transfer material passage as in the illustrated example, the airflow between the inside and outside of the developing device can be more effectively blocked.

[0015]

[Effect of the device]

 As described above, according to the present invention, by arranging the first and second leakage prevention means below the casing opening so that the tips of the first and second leakage prevention means sequentially approach the surface of the photoconductor, the developer from the casing opening is prevented. It is possible to completely prevent falling and leakage of the toner cloud, and it is possible to keep the inside of the electrophotographic device clean for a long time without contaminating the inside of the electrophotographic device.

[Brief description of drawings]

FIG. 1 is a schematic front view showing an example of a developing device of an electrophotographic apparatus according to the present invention.

FIG. 2 is an enlarged view of a portion of FIG.

[Explanation of symbols]

 1 Photosensitive Drum 10 Developing Device 11 Casing 12 Developing Sleeve 20 First Leakage Preventing Member 30 Second Leakage Preventing Member 111 Opening

Claims (1)

[Scope of utility model registration request] 1. A developing device of an electrophotographic apparatus, comprising: a casing having an opening facing a surface of a photoconductor; and a developing sleeve arranged in the casing to supply a developer to the photoconductor, at a lower end portion of the opening. A first developer leakage prevention member that is arranged so that its tip is close to the surface of the photoconductor and that prevents the developer from falling through the opening, and the tip is below the first leakage prevention member.
A second leakage prevention member which is arranged so as to be positioned toward the photoconductor side with respect to a vertical line passing through the tip of the leakage prevention member and which has a receiving portion for receiving the developer falling from the first leakage prevention member. And a developing device for an electrophotographic apparatus.