JPH0651631A - Developing device - Google Patents

Abstract

PURPOSE:To surely detect the quantity of one-component toner in a developing device by using a conductive thin layer triboelectrified by contacting with toner. CONSTITUTION:The toner 20 in a housing 30 is carried to the side of a subroller 50 while being stirred by a rotary blade 60, to develop a latent image on a photosensitive drum 10 by a developing roller 40. The toner 20 stirred in the housing 30 is rubbed on the conductive thin layer 70 to electrostatically charges the larger 70. The capacitor 81 of a toner quantity detecting circuit 80 is charged by the electrostatic charge of the conductive thin layer 70 and discharged by a discharge switch 82. When discharge timing by the discharge switch 82 is longer than a specified time, a control part 83 allows a toner empty display unit 84 to operate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a printer, a facsimile, an electrophotographic copying machine, and more particularly, to an electrostatic latent image formed on a photosensitive member.
The present invention relates to a developing device that develops using component-based toner.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a laser printer, a one-component toner, especially a non-magnetic toner, is used to develop an electrostatic latent image formed on a photosensitive drum. The development method is adopted.

In a developing device using a non-magnetic one-component toner, toner is contained in a housing, and the toner is agitated by an agitating member so that it is triboelectrically charged. The triboelectrically charged toner is supplied to the surface of the developing roller arranged in the housing,
A thin layer of toner is formed on the surface of the developing roller by the blade pressed against the developing roller. The thin layer of toner formed on the surface of the developing roller is conveyed to the photosensitive drum. A predetermined bias voltage is applied to the developing roller with respect to the photosensitive drum. When a thin layer of toner conveyed on the surface of the developing roller contacts the photosensitive drum, the toner on the surface of the developing roller is It is attached to the electrostatic latent image on the photoconductor drum by the bias voltage applied to. As a result, the latent image on the photosensitive drum is developed with toner.

In such a one-component developing device, a light transmission type sensor is usually used for measuring the amount of toner in the housing. In such an optical sensor, for example, a light emitting portion is provided on the bottom surface of a portion of the housing where the toner is stored, and a light receiving portion is provided on the upper surface facing the light emitting portion. Then, the amount of toner in the housing is measured based on the amount of light received by the light receiving unit.

[0005]

However, in such a developing device, since the optical sensor is used for detecting the toner amount, the light emitting surface and the light receiving surface of the optical sensor are
If the toner is contaminated, the toner amount may not be accurately detected. For this reason,
A rotary blade that stirs the toner is provided with a cleaning member that slidably contacts the light emitting surface and the light receiving surface of the optical sensor to clean the respective surfaces. However, even such a cleaning member cannot remove fine toner from the light emitting surface and the light receiving surface, and the amount of toner in the housing cannot be accurately detected.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a developing device capable of accurately detecting the amount of toner in the housing.

[0007]

The developing device of the present invention is
A housing containing a component type toner, a stirring member for stirring and charging the toner in the housing, and a stirring member are disposed in the housing, and a thin layer of the one component type toner is formed on the surface thereof to form a photoconductor. A developing roller for carrying the toner to a conductive member, and a conductive member disposed in the housing so as to be frictionally charged by the toner stirred by the stirring member,
A means for detecting the charge amount of the conductive member, a display means for indicating that the amount of toner in the housing is decreasing,
And a control unit that controls the display unit based on the detection result of the charge amount detection unit, whereby the above object is achieved.

[0008]

The toner in the housing is agitated by the agitating member and frictionally charged. At the same time, the toner is brought into sliding contact with the conductive member, so that the conductive member is triboelectrically charged. The charge amount of the conductive member is detected by the charge amount detection means to estimate the toner amount in the housing. Then, when the amount of charge on the conductive member is small, it is determined that the amount of toner in the housing has decreased, and the control unit operates the display unit.

[0009]

EXAMPLES The present invention will be described below with reference to examples. As shown in FIG. 1, the developing device of the present invention includes a housing 30 that accommodates the one-component non-magnetic toner 20.
The housing 30 is provided with an opening 31 at a portion facing the photoconductor drum 10.

The photosensitive drum 10 in the housing 30
A developing roller 40 made of a conductive elastic material is provided in the side portion close to. The developing roller 40 is in contact with the photoconductor drum 10 through the opening 31, and the developing roller 40 is rotated synchronously with the photoconductor drum 10 so that their contact surfaces move in the same direction. . A sub-roller 50, which is in pressure contact with the lower part of the developing roller 40, is arranged on the far side of the developing roller 40 from the photosensitive drum 10. The sub-roller 50 is rotated in the same direction as the developing roller so that the contact surfaces of the developing roller 40 move in opposite directions.

Three agitating chambers 32 each having an arcuate bottom surface are continuously provided in the horizontal direction on the side farther from the developing roller 40 than the sub roller 50. A rotary blade 60 is provided in each stirring chamber 32, and each rotary blade 6
In the case of 0, the toner 20 in the stirring chamber 32 is stirred to be negatively charged. The toner that has sequentially passed through the stirring chambers 32 by the rotating blades 60 is supplied to the sub roller 50.

A bias voltage of, for example, + 400V is applied to the sub-roller 50, and a voltage of + 200V, which is lower than the bias voltage applied to the sub-roller 40, is applied to the developing roller 40 to which the sub-roller 50 is pressed. ing.

The charged toner supplied to the sub roller 50 is conveyed to the surface of the developing roller 40 by the electric field between the sub roller 50 and the developing roller 40.

Above the sub roller 40, the developing roller 4
A blade 41 for thinning the toner conveyed on the 0 surface is provided so as to be in sliding contact with the developing roller 40. The charged toner, which is conveyed while thinning the surface of the developing roller 40, comes into contact with the portion of the photosensitive drum 10 where the electrostatic latent image is formed by pressure, and is biased by the bias voltage applied to the developing roller 40. Attached to 10. As a result, the latent image on the surface of the photoconductor drum 10 is developed with toner. The toner carried on the surface of the developing roller 40 without being attached to the photosensitive drum 10 is scraped off by the sub roller 40.

On the arcuate bottom surface of each stirring chamber 32,
Each conductive thin layer 70 is covered. As the conductive thin layer 70, for example, a coat made of conductive fluorine is used. The conductive thin layer 70 is in contact with the toner 20 which is stirred and charged by the rotating blade 60 in the stirring chamber 32. When the toner 20 is present in the agitating chamber 32, the toner 20 is agitated by the rotating blade 60 so that the toner 20 flows and the conductive thin layer 7 is discharged.
0 is charged by friction with the toner 20.

A toner amount detection circuit 80 arranged outside the housing 30 is connected to the conductive thin layer 70. The toner amount detection circuit 80 includes a conductive thin layer 70 by frictional charging.
Has a capacitor 81 interposed between the conductive thin layer 70 and the ground, and a discharge switch 82 connected in parallel with the capacitor 81 so as to accumulate the electric charge generated in the capacitor. . In the capacitor 81, when the accumulated charge amount reaches a predetermined value, the discharging switch 82 operates,
The electric charge accumulated in the capacitor 81 is discharged. The output between the discharge switch 82 and the ground is the control unit 8
3, the control unit 83 monitors the timing at which the discharge switch 82 is operated. Control unit 8
Toner empty indicator 84 is connected to 3,
The control unit 83 operates the toner empty indicator 84 when the discharge switch 82 is not operated for a predetermined time.

In the developing device having such a structure, when the three stirring chambers 32 in the housing 30 are filled with the toner 20, the toner 20 is conveyed to the sub roller 50 while being stirred by the rotating blade 60. It The toner 20 stirred in the stirring chamber 32 is brought into sliding contact with the conductive thin layer 70 provided on the bottom surface thereof, and the conductive thin layer 70 is charged by friction with the toner 20. The electric charge generated by the charging is charged in the capacitor 81 of the toner amount detection circuit 80. When the toner 20 is agitated in the agitation chamber 32, the charge amount of the conductive thin layer 70 sequentially increases, and the charge amount charged in the capacitor 81 sequentially increases. And
When the amount of charge in the capacitor 81 reaches a predetermined value, the discharging switch 82 is operated to discharge the charge in the capacitor 81. After that, the toner 230 remains in the stirring chamber 32.
By being stirred, the capacitor 81 is sequentially charged, and the same operation is repeated.

Toner 20 conveyed to sub-roller 50
Are supplied to the surface of the developing roller 40 due to the contact between the sub roller and the developing roller 40 and the bias voltage difference therebetween, and the blade 41 forms a thin layer of toner on the surface of the developing roller 40. Then, the latent image on the photosensitive drum 10 is developed by the thin toner layer. When the toner in the housing 30 is sequentially consumed in this way, the amount of the toner 20 in the stirring chamber 32 decreases, and the triboelectric charge amount of the toner on the conductive thin layer 70 decreases. As a result, it takes a long time for the amount of charge charged in the capacitor 81 to reach a predetermined value. The control unit 83 uses the discharge switch 82.
When the discharge switch 82 has not been operated for a predetermined time in consideration of the increase in the operation interval of, the toner empty indicator 84 is operated as if the toner amount in the housing 32 has decreased by a predetermined amount. Let As a result, it is notified that the amount of toner in the housing 30 is below the predetermined value.

FIG. 2 shows a developing device according to another embodiment of the present invention. In this developing device, a toner amount detection circuit 80 having a current limiting resistor 85 connected to the conductive thin layer 70 and an ammeter 86 connected to the resistor 85 is used, and the output of the ammeter 86 is used. Are given to the control unit 83.

In this embodiment, the toner 20 in the stirring chamber 32 is
When the conductive thin layer 70 is charged by, a current flows through the ammeter 86 of the toner amount detection circuit 80, and the current is detected by the ammeter 83. Then, when a predetermined amount of current flows, the control unit 83 determines that a sufficient amount of toner is present in the stirring chamber 32 and does not operate the toner empty indicator 84. When the amount of toner in the stirring chamber 32 decreases and the amount of charge on the conductive thin layer 70 decreases, the amount of current flowing through the ammeter 86 also decreases, and when the amount of current falls below a predetermined value, the control unit 83 The toner empty indicator 84 is operated. This informs that the amount of toner in the housing 30 is decreasing.

In the above-described embodiment, the conductive thin layer 70 coated on the bottom surface of the housing 30 is used as the conductive member that is frictionally charged with the toner. However, the conductive thin layer 70 is not limited to this. The rotary blade 60 may be made of a conductive material to detect the charge amount when the rotary blade 60 is frictionally charged by the toner.

[0022]

As described above, the developing device of the present invention uses the conductive thin layer that causes frictional charging by contacting the toner that moves while being stirred in the housing, so that the toner sensor can be used without using the toner sensor. Empty detection of. The conductive thin layer has a simple structure as compared with the toner sensor, is not bulky, and does not require cleaning. Therefore, cost reduction and downsizing of the developing device can be achieved.

[Brief description of drawings]

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

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

[Explanation of symbols]

 10 Photoconductor Drum 20 Toner 30 Housing 40 Developing Roller 50 Sub-roller 60 Rotating Blade 70 Conductive Thin Layer 80 Toner Amount Detection Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keio Fujita 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Inventor Yuuki Ito 1-2-2 Tamatsukuri, Chuo-ku, Osaka Within Mita Engineering Co., Ltd.

Claims (1)

[Claims] 1. A housing containing a one-component toner, an agitating member for agitating and charging the toner in the housing, and a thin layer of the one-component toner disposed on the surface of the housing. A developing roller that forms a sheet and conveys it to a photoconductor, a conductive member disposed in the housing so as to be frictionally charged by the toner stirred by the stirring member, and a detection amount of the conductive member. And a control unit for controlling the display unit based on a detection result of the charge amount detection unit, and a display unit for displaying that the toner amount in the housing is decreasing.