JPH04107485A - Developing device - Google Patents

Abstract

PURPOSE:To prevent toner getting on air flow generated in accordance with the rotation of a stirring blade from being splashed to the outside of a developing container by providing a means which uniformizes a gap between the lower part of a developing roll and a housing and a gap between the lower part of the stirring blade and the housing. CONSTITUTION:A member 11 is disposed in the rotating shaft direction of the developing container 1 on the bottom plate 1a of the developing container 1. Then, the uniform gaps are formed between the bottom plate 1a of the container 1 and the outside circumference part of the developing roll 4 and between the bottom plate 1a and the outside circumference part of the stirring blade 3. The developing roll 4 in the container 1 is oppositely arranged at a slight interval between a photosensitive drum 9 through an aperture part. That means, the prescribed uniform gap (t) is formed between the inside of the bottom plate 1a of the container 1 and the lower part of the outside circumference of the roll 4 and between the bottom plate 1a and the lower part of the outside circumference of the blade 3 by the member 11. Thus, the toner whose electrostatic coupling force with carrier is weak is prevented from flowing to the aperture part by the air flow generated in accordance with the rotation of the developer stirring blade.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device for an electrophotographic recording device.

(Prior Art) Conventionally, in an electrophotographic recording device, a charged photoreceptor drum is irradiated with a light source to form an electrostatic latent image on its surface, and toner is deposited on the electrostatic latent image. After development, the topu image is transferred onto a recording medium δ.

The electrophotographic recording apparatus described above is equipped with a developing device for applying toner to an electrostatic latent image formed on a photosensitive drum to form a visible image.

FIG. 3 is a schematic diagram of a conventional developing device.

In the figure, 1 is a two-component developer 2 consisting of toner and magnetic carrier (hereinafter, a mixture of toner and magnetic carrier is referred to as "developer"; otherwise, "toner" or "magnetic carrier" is referred to as "developer"). ), 3 is a stirring blade for stirring the developer 2 provided in the developer container 1, and 4 is provided in the developer container 1 and supports the developer 2 on its surface. A developing roll 5 that conveys toner to the photosensitive tram 9 is a regulating member that regulates the thickness of the developer 2 carried on the developing roll 4 .

Further, 6 is a toner concentration sensor that detects the toner concentration in the developer 2, and 7 is a toner replenishment roll that replenishes the inside of the developer container 1 with the toner replenished by the toner cartridge 8.

In the developing device having the above configuration, the developer 2 in the developing container 1
When the toner and the magnetic carrier are stirred by the stirring blade 3, the toner and the magnetic carrier are charged to opposite polarities due to frictional charging. Then, the toner concentration sensor 6 detects the mixing ratio of toner and magnetic carrier, that is, the toner concentration, and maintains it within a predetermined range.

In this state, the developer 2 is attracted to the magnet 4a in the developing roll 4, has a constant thickness tl by the regulating member 5, and is supported on the surface of the developing roll 4.

When the developing roll 4 rotates, the magnetic carrier and the toner carried thereby move to a position facing the photosensitive drum 9.

On the other hand, the surface of the photosensitive drum 9 is uniformly charged by a charger and selectively exposed to light by a light source to form an electrostatic latent image.

Therefore, if the composition of the magnetic carrier and toner is configured so that the toner in the developer 2 is charged to the same polarity as the surface of the photosensitive drum 9, a Coulomb force is created between the exposed area and the developer 2. act. At this time, since the magnetic carrier is captured by the magnetic force of the magnet 4a in the developing roll 4, only the toner is attracted to the surface of the photosensitive drum 9 and developed.

(Problem to be Solved by the Invention) However, in the conventional developing device described above, since the agitating blade 3 is provided to maintain the toner concentration of the developer 2 within a predetermined range and make it uniform, the developing device It scatters outside of container 1. That is, when the stirring blade 3 rotates, an air flow as shown by the arrow F in FIG. The developer container 1 passes through the gap between the inner surface of the bottom plate la of the developer container 1 and the developer roll 4.
The developer may land on the opening periphery 1b or be scattered outside the developer container 1. Then, the scattered toner contaminates other devices inside the electrophotographic recording apparatus and prevents normal image formation, and the toner that falls onto the medium feeding path stains the recording medium.

The present invention solves the above-mentioned problems of the conventional developing device and provides a developing device that can prevent the toner carried by the air flow generated by the rotation of the stirring blade from scattering outside the developing container. The purpose is to

(Means for Solving the Problem) For this purpose, in the developing device of the present invention, an opening is formed at least in the front surface of the housing facing the electrostatic latent image carrier, and the electrostatic latent image is formed in the opening. A developing roll is rotatably disposed within the housing so as to be close to and face the carrier.

A stirring blade is further rotatably disposed within the housing so as to be close to and face the developing roll, and stirs the developer within the housing.

Further, a means is provided for making uniform the gaps formed between the lower part of the developing roll and the casing, and between the lower part of the stirring blade and the casing. For this purpose, a separate member is provided on the bottom surface of the casing, or the bottom surface of the casing itself is deformed.

Further, the size of the gap is approximately the same as the thickness of the developer supported on the developing roll.

(Function) According to the present invention, as described above, an opening is formed in at least the front surface of the casing facing the electrostatic latent image carrier, and the opening is formed close to and facing the electrostatic latent image carrier in the opening. A developing roll is rotatably disposed within the housing, and a stirring blade is rotatably disposed close to and facing the developing roll to agitate the developer within the housing. do.

Therefore, the developer inside the housing is stirred by the stirring blade, held by the developing roll, and sent to the electrostatic latent image carrier.

Means is provided for making uniform the gaps formed between the lower part of the developing roll and the casing, and between the lower part of the stirring blade and the casing, and the size of the gap is determined by the size of the developing roller supported on the developing roll. The thickness is almost the same as that of the agent.

Therefore, even if an airflow is generated by the rotation of the stirring blade, the gap between the developing roll and the bottom plate of the casing at the opening is covered with the developer, so that the toner flies on the airflow. Things will disappear.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a developing device showing an embodiment of the present invention.

In the figure, 1 is a developing container, 2 is a two-component developer consisting of toner and magnetic carrier, 3 is a stirring blade, 4 is a developing roll as a developer supply means, and 5 is a regulating member that regulates the amount of developer supplied. . Further, 6 is a toner density sensor, 7 is a toner supply roll, 8 is a toner cartridge, and 9 is a photosensitive tram as an image carrier. The developer container 1 is disposed adjacent to the photosensitive drum 9 and has an opening in the side wall of the surface facing the photosensitive drum 9.

A member 11 is attached to the bottom plate 1a of the developer container 1.
is disposed in the direction of the rotation axis of the developer container 1 to form a uniform gap between the bottom plate 1a of the developer container 1 and the outer periphery of the developing roll 4, and between the bottom plate 1a and the outer periphery of the stirring blade 3. The developing roll 4 in the developing container 1 is disposed opposite to the photosensitive drum 9 with a slight distance therebetween via the opening. When performing development, the photosensitive drum 9, the developing roll 4, and the stirring blade 3 are rotated in the C direction, the D direction, and the E direction by a drive source (not shown). At this time, the developer collected around the developing roll 4 adheres to it due to the magnetic force of the sleeve 4a, and only the toner is transferred to the portion facing the photosensitive drum 9.

The regulating member 5 controls the thickness of the developer 2 carried on the surface of the developing roll 4 (the carrier is attached to the developing roll 4 and the toner is attached to this carrier, so the thickness of the magnetic carrier and the toner). regulate.

Here, the member 11 forms a predetermined uniform gap between the inside of the bottom plate 1a of the developing container 1 and the lower outer periphery of the developing roll 4, and between the bottom plate 1a and the lower outer periphery of the stirring blade 3.

The member 11 is made of a non-magnetic material such as aluminum material, synthetic resin, com material, etc., and the gap t is
When the thickness of the developer 2 held above is t, t>g
The number is set so that

Making the gap as close as possible to Ll has a great effect in reducing toner scattering, but when 1<1°, the tip of the developer 2 on the developing roll 4 comes into contact with the surface of the member 11. In this case, the conveyance of the developer 2 on the developer roll 4 deteriorates, a part of the developer 2 may flow out of the developer container 1 from the developer container opening periphery 1b, and the rotational load torque of the developer roll 4 increases. Resulting in. For this reason, a flexible film lla is disposed on the surface of the member 11 facing the developing roll 4 so as to be uniformly adhered in the direction of the rotation axis. The film I
la is a gap t so that the tip does not come into contact with the photosensitive drum 9;
Even if the gap t2 is made larger than t, and the gap t2 is gradually decreased as the distance from the tip increases, the amount of developer 2 on the developing roll 4 can be increased.
The gap is narrowed to a small value t3 in the developer container 1, and thereafter the gap is arranged so as to be larger than tl. The film lla is preferably a plastic film, other synthetic resin made of non-magnetic material, rubber, or the like.

In the developing device configured as described above, when the stirring blade 3 rotates, an air flow shown by an arrow F is generated in the developer container 1, and even if there is toner riding on this air flow, the gap between the film lla and the developing roll 4 is 1. .3, the film lla and the developer 2 are in pressure contact, so the movement of the toner is prevented.

Therefore, the toner carried by the air flow generated by the 30 rotations of the stirring blade is prevented from scattering outside the developer container 1 and staining the inside of the electrophotographic recording apparatus.

FIG. 2 is a schematic diagram of a developing device showing another embodiment of the present invention.

In the figure, the bottom plate 1a is formed so that the gaps between the bottom plate 1a of the developer container 1 and the lower part of the outer periphery of the developing roll 4 and between the bottom plate 1a and the lower part of the outer periphery of the stirring blade 3 are the same as in FIG. It is. Furthermore, a film lla similar to that shown in FIG. 1 is adhered to the inner surface of the developer container bottom plate 1a in the direction of the rotation axis.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, an opening is formed in at least the front surface of the casing facing the electrostatic latent image carrier, and the electrostatic latent image carrier is formed in the opening. A developing roll is rotatably disposed within the housing so as to be close to and facing the developing body, and a stirring blade is rotatably disposed so as to be close to and facing the developing roll. Means is provided to equalize the gaps formed between the lower part of the roll and the two casings, and between the lower part of the stirring blade and the casing, and the size of the gap is determined based on the size of the developer carried on the developing roll. The thickness is almost the same.

Therefore, toner having a weak electrostatic bond with the carrier is prevented from flowing into the opening due to the air flow generated as the developer stirring blade rotates.

Therefore, it is possible to suppress contamination of other devices within the electrophotographic recording apparatus and deterioration of image quality.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a developing device showing an embodiment of the present invention, and FIG.
Figure 3 is a schematic diagram of a developing device showing another embodiment of the present invention.
The figure is a schematic diagram of a conventional developing device. DESCRIPTION OF SYMBOLS 1... Developing container, 1a... Bottom plate, 1b... Opening periphery, 2... Two-component developer, 3... Stirring blade, 4...
・Developing roll, 4a... Sleeve, 5... Regulating member,
6... Toner density sensor, 7... Toner supply roll, 8... Toner cartridge, 9... Photosensitive drum,
Ila...film. Patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Scope of Claims] (a) A casing having at least an opening on the front surface facing the electrostatic latent image carrier; (b) A casing that faces the electrostatic latent image carrier in close proximity to the electrostatic latent image carrier at the opening. (c) a developing roll rotatably disposed within the casing; (c) a developing roll rotatably disposed within the casing so as to be close to and opposite to the developing roll; a stirring blade for stirring; (d) means for making uniform gaps formed between the lower part of the developing roll and the housing, and between the lower part of the stirring blade and the housing, and (e) dimensions of the gap. A developing device characterized in that the thickness of the developer is approximately the same as the thickness of the developer carried on the developing roll.