JP2795345B2 - Electrostatic image developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing apparatus that forms an image via an electrostatic image and is applied to an image forming apparatus such as a laser printer or an electrophotographic apparatus. About.

[Technological background]

For example, a laser printer generally includes a charging device for uniformly charging the surface of a photoconductor, an exposure optical device for performing exposure to form an electrostatic image on the surface of the photoconductor, and a toner An electrostatic image developing device for forming a toner image by developing the toner image, a transfer device for transferring the toner image to a transfer material, a fixing device for fixing the toner image on the transfer material, A cleaning device for removing toner remaining on the photoconductor.

The photoconductor has, for example, a rotating drum shape or a rotating belt shape, and the electrostatic image formed on the surface thereof is sequentially developed through the electrostatic image developing device with the rotation movement of the photoconductor. You.

However, in order to achieve good development without fogging, it is required that the toner has a stable triboelectric charging property. Therefore, in an electrostatic image developing device, the developer is agitated by stirring the developer. An agitating member for frictionally charging in an appropriate range is provided.

If the stirring of the developer is insufficient, a phenomenon that the replenishment toner accumulates at the upper portion and forms a cavity inside (hereinafter, referred to as a “kama phenomenon”) occurs, and the transport of the developer layer to the developing area occurs. There is a problem of instability.

[Conventional technology]

The following means are conventionally known as means for stirring the developer.

Means in which a screw-shaped stirring member is rotatably disposed in the developing container, and is rotated by a driving system disposed outside the developing container.

Means for disposing a cantilever vibration plate in a developing container and vibrating the vibration plate using the rotational force of a developing roller.

[Problems to be solved by the invention]

However, in the above-mentioned means, since the drive system of the stirring member is disposed outside the developing container, a separate means for transmitting the rotational driving force is required, which complicates the structure and has a problem of increasing the size. .

Further, in the above-mentioned means, there is a problem that the stirring becomes insufficient when the amount of the developer in the developing container is small.

By the way, when the amount of the developer in the developing container is less than a certain amount, the frictional charging property of the toner becomes unstable, and the amount of the toner supplied to the developing area also decreases, which causes a decrease in image density. Means for detecting the quantity are needed.

However, conventionally, since the amount of the developer is detected by directly measuring the weight of the developer, there has been a problem that the configuration of the detecting means is considerably complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrostatic image developing apparatus which can sufficiently agitate a developer with a simple structure and can easily detect the amount of the developer. Is to do.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an electrostatic image comprising a developing roller for transporting a developer layer carried on an outer peripheral surface thereof to a developing area, and a stirring member for stirring the developer. In the developing device, the stirring member is formed by connecting a single or a plurality of ring portions with a connecting portion, and a pressing member that applies an elastic force to a pressing shaft that protrudes outward from the center of the ring portion is used to form the ring portion. Are arranged so as to elastically contact the outer peripheral surface of the developing roller, and the ring portion is rotated following the rotation of the developing roller.

Further, a developer amount detecting means including a magnet provided on the stirring member for detecting the developer amount based on the rotation speed of the stirring member is provided.

 Further, the stirring member is made of a magnetic material.

[Action]

Due to the action of the pressing member, the ring portion of the stirring member is arranged in a state of elastically abutting on the outer peripheral surface of the developing roller via the pressing shaft, so that when the developing roller rotates, the ring portion of the stirring member develops. The developing roller receives the rotational frictional force from the roller and rotates following the rotation of the developing roller.
Therefore, the developer is sufficiently agitated by the agitating member that is driven and rotated via the ring portion.

As described above, since the stirring member is driven to rotate following the rotation of the developing roller, it is not necessary to provide a dedicated drive system for driving the stirring member to rotate outside the developing container.

And, since the rotation speed of the stirring member changes depending on the resistance force received from the developer, the resistance at the time of stirring is large if the amount of the developer is large, so that the slip of the ring portion of the stirring member with respect to the developing roller increases, As a result, the rotation speed of the stirring member decreases. On the other hand, when the amount of the developer is small, the resistance at the time of stirring becomes small, so that the slip of the ring portion with respect to the developing roller is reduced, and as a result, the rotation speed of the stirring member is increased. Therefore, the developer amount can be detected based on the rotation speed of the stirring member.

Since the amount of developer is detected based on the rotation speed of the stirring member, the structure of the developer amount detecting means is simpler than that of the means for detecting the weight of the developer amount.

When the stirring member is made of a magnetic material, in the case of a developing roller having magnetism, in addition to the elastic force of the pressing member, the ring itself of the stirring member is elastically moved on the outer peripheral surface of the developing roller by the developing roller and the magnetic force. And the pressure contact force between the ring portion and the developing roller is sufficient.

[Specific configuration of the invention]

 Hereinafter, the configuration of the present invention will be specifically described.

1 and 2 are schematic views showing an example of the electrostatic image developing device according to the present invention.

In FIG. 1, reference numeral 10 denotes a developing roller, 20 denotes a stirring member, 30 denotes a regulating blade, 40 denotes a developing container, 50 denotes a developing area, and 60 denotes a rotating drum-shaped photoconductor.

The developing roller 10 has a cylindrical developer carrier (hereinafter also referred to as a “developing sleeve”) 11 made of a non-magnetic material and rotated in the direction of arrow A, and an arrow B arranged inside the developing sleeve 11. Magnet roller 12 driven to rotate in the direction
And

These developing sleeve 11 and magnet roller 12
Extends outside from the side wall of the developing container 40 and is connected to a drive system (not shown) including gears and the like.

The stirring member 20 is formed by connecting a single or a plurality of ring portions 21 with a connecting portion 22, and the ring portion 21 is disposed in a state of elastically abutting on the outer peripheral surface of the developing roller 10. The connecting portion 22 extends along the axial direction of the ring portion 21 at a position displaced from the center of the ring portion 21 to the outer peripheral side. The stirring member 20 is preferably made of a magnetic material.

In the example shown in the drawing, a pressing shaft 26 projecting outward from the center of the ring portion 21 is constantly moved in a direction approaching the outer peripheral surface of the developing roller 10, that is, the developing sleeve 11 by a pressure contact member 24 which has received elastic force by a spring 23. Pressed. Accordingly, the ring portion 21 is rotated following the rotation of the developing sleeve 11, and the connecting portion 20 is rotated around the holding shaft 26. The developer 80 is stirred by such rotation of the stirring member 20. When the stirring member 20 is made of a magnetic material, the ring portion 21 of the stirring member 20 itself is developed by the magnetic force of the magnet roller 12.
Since the outer peripheral surface of the developing unit 11 is elastically brought into contact with the outer peripheral surface of the developing unit 11, the pressing force between the ring unit 21 and the developing sleeve 11 is sufficient.

Further, as shown in FIG. 3, a pressing shaft 26 of the stirring member 20 may be constantly pressed in a direction approaching the developing sleeve 11 by an elastic plate 25 made of a phosphor bronze plate.

The pressing member 24 or the elastic plate 25 has a pressing direction in which the ring portion 21 presses the ring portion 21 against the developing sleeve 11.
A force may be applied to any part of the stirring member 20. However, it is preferable to suppress the center of rotation as in the example shown in the drawing, in that the rotation center does not cause resistance.

Further, as shown in the example of the drawing, by pressing the holding shaft 26 outwardly of the ring portion 21, friction between the inner wall of the developing container 40 and the ring portion 21 is prevented, and displacement in the axial direction is prevented. This is advantageous in terms of regulation.

Although the number of the ring portions 21 is not particularly limited, at least one end of the stirring member 20, preferably at both ends, a ring portion is provided.
Preferably, 21 is present. Also, one ring portion 21
, The number of turns is preferably, for example, about 1 to 5.

The toner or toner and carrier triboelectrically charged by being agitated by the agitating member 20 in the developing container 40 are layered on the surface of the developing sleeve 11 by the magnetic force of the magnet roller 12, and the developing sleeve 11
Move following the rotation of. Then, the thickness is regulated by the regulating blade 30 to form a developer layer having a constant thickness, and this developer layer is supplied to the development region 50.

This developer layer is supplied to the development area 50, where the arrow F
The electrostatic latent image on the photoreceptor 10 rotated and moved in the direction shown by the arrow is developed to form a toner image.

FIG. 4 is a schematic view of an example of the developer amount detecting means 70. The developer amount detecting means 70 detects the rotation speed of the stirring member 20, and detects the amount of the developer remaining in the developing container 40 based on the detection signal. In the illustrated example, the developer amount detecting means 70 includes a magnet 71 provided on the stirring member 20 (see also FIGS. 1 and 2) and a magnetic sensing reed switch 72 fixed to the developing container 40 ( 1 and 2), a pulse generating circuit 74, a monostable multivibrator 75, and a microprocessor 76. In the pulse generating circuit 74, C is a capacitor, R is a resistor, D is a diode, and E is a DC power supply.

In the developer amount detecting means 70, the stirring member 20
Each time the magnet 71 rotates, the magnet 71 turns on the reed switch 72, and at this time, a discharge circuit of the capacitor C is formed.
Therefore, each time the reed switch 72 is turned on, the capacitor C of the pulse generation circuit 74 is discharged, and a trigger pulse is generated. This trigger pulse causes the monostable multivibrator 75 to oscillate. Therefore, the output pulse interval of the monostable multivibrator 75 is consequently
(Inversely proportional) to the rotational speed of the motor.

FIG. 5 shows an example of the correlation between the output pulse interval of the monostable multivibrator 75 and the amount of the developer in the developing container 40. As can be understood from the figure, the output pulse interval of the monostable multivibrator 75 decreases as the developer amount decreases. X indicates the lower limit of the allowable developer amount, and Y indicates the output pulse interval of the monostable multivibrator 75 when the developer amount reaches the lower limit X.

Microprocessor 76 is a monostable multivibrator
When the output pulse interval of the monostable multivibrator 75 becomes Y or less, that is, when the developer amount becomes less than the lower limit value X, the developer amount is automatically detected by detecting the output pulse interval of 75. When this happens, a display lamp or the like is turned on to notify the operator of toner supply.

In the present invention, the developer amount detecting means 70 is not limited to the above configuration, and various other configurations can be adopted.

According to the apparatus having the above configuration, when the developing roller 10 rotates, the ring portion of the stirring member 20 elastically abutted against the outer peripheral surface of the developing roller 10 by the action of the pressing member 24 or the elastic plate 25 as the pressing member. The rotation of the developing roller 10 follows the rotation of the developing roller 10 by receiving the rotational frictional force from the developing roller 10. Therefore, the developer in the developing container 40 is sufficiently stirred by the rotation of the stirring member 20.

Since the ring portion 21 of the stirring member 20 is configured to be driven to rotate following the rotation of the developing roller 10, the developing container
It is not necessary to provide a dedicated drive system for rotationally driving the stirring member 20 outside the stirrer 40, so that the apparatus can be simplified.

The rotation speed of the stirring member 20 changes depending on the resistance force received from the developer. Therefore, if the amount of the developer is large, the resistance at the time of stirring is large, and the slip of the ring portion 21 of the stirring member 20 with respect to the developing roller 10 increases. As a result, the rotation speed of the stirring member 20 decreases. On the other hand, when the amount of the developer is small, the resistance force at the time of stirring becomes small, so that the developing roller
The slip of the ring portion 21 with respect to 10 decreases, and as a result, the rotation speed of the stirring member 20 increases. Therefore, the developer amount can be detected by the developer amount detecting means 70 based on the rotation speed of the stirring member 20.

Since the amount of developer is detected based on the rotation speed of the stirring member 20, the structure of the developer amount detecting means 70 is simpler than the means for detecting the weight of the amount of developer.

The developer applicable to the electrostatic image developing device according to the present invention may be any one of a one-component developer composed of only a magnetic toner or a non-magnetic toner and a two-component developer composed of a toner and a carrier. Is also good.

〔The invention's effect〕

As described above in detail, according to the present invention, the ring portion of the stirring member is elastically brought into contact with the outer peripheral surface of the developing roller by the action of the pressing member, and the ring portion follows the rotation of the developing roller. , The agitation member does not need a dedicated drive system, and the structure is simplified.
The pressing shaft, to which the elastic force is applied by the pressing member, is set to protrude outward from the ring portion, thereby preventing the friction between the inner wall of the developing container and the ring portion and restricting the axial displacement. be able to.

Further, when the developer amount detecting means detects the developer amount based on the rotation speed of the stirring member, the structure is simpler than when the weight of the developer is detected.

When the stirring member is made of a magnetic material, the ring portion can be sufficiently pressed against the developing roller having magnetism in addition to the elastic force of the pressing member.

[Brief description of the drawings]

FIGS. 1 and 2 are front views and cross-sectional plan views, respectively, illustrating an example of an electrostatic image developing apparatus according to the present invention. FIG. 4 is a vertical sectional front view for explaining another example of the image developing apparatus, FIG. 4 is an explanatory view showing a main part of a developer amount detecting means, and FIG. 5 is an output pulse interval of a monostable multivibrator of the developer amount detecting means. FIG. 5 is an explanatory diagram showing a relationship between the developer amount and the developer amount in the developing container. 10: developing roller, 11: developing sleeve 12: magnet roller, 20: stirring member 21: ring portion, 22: connecting portion 23: spring, 24: pressing member 26: holding shaft, 30 … Regulatory blade 40… Developer container, 50… Development area 60… Photoconductor, 70… Developer amount detection means 71… Magnet, 72… Reed switch 74… Pulse generation circuit 75… Monostable Multivibrator 76 Microprocessor 80 Developer C Capacitor R Resistance D Diode E DC power supply

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/08

Claims (3)

(57) [Claims] 1. An electrostatic image developing apparatus comprising: a developer layer carried on an outer peripheral surface thereof; a developing roller for transporting the developer to a developing area; and a stirring member for stirring the developer. However, a single or a plurality of ring portions are connected by a connecting portion, and the pressing portion that applies an elastic force to a pressing shaft protruding outward from the center of the ring portion causes the ring portion to have an outer peripheral surface of the developing roller. An electrostatic image developing device, wherein the ring portion is rotated following the rotation of the developing roller. 2. A static electricity detecting device according to claim 1, further comprising a developer amount detecting means including a magnet provided on said stirring member for detecting the developer amount based on a rotation speed of said stirring member. Electro-image developing device. 3. The electrostatic image developing device according to claim 1, wherein the stirring member is made of a magnetic material.