JPH06324562A - Developing device - Google Patents

Abstract

PURPOSE:To enable development at invariable concentrations by providing within an area of rotation a member for reducing or neutralizing the amount of charge of a developer remaining on the surface of a developing roller. CONSTITUTION:In a developing device 4, a developing roller 12, a developer supply roller 13 and an agitator 14 are drivingly rotated and a developer in a developer container 11 is made uniform by the agitator 14 and bonded to the periphery of the developing roller 12 by means of the developer supply roller 13. As the developing roller 12 is rotated, the developer 15 is rubbed by means of a blade 16 being in sliding contact with the surface of the roller 12 and is therefore positively or negatively charged so as to bond to the peripheral surface of a photoreceptor drum 1. Part of the developer 15 which remains on the surface of the developing roller 12 is slid against a charge neutralizing member 11b serving also as a leakage arrestor 17 and thus its amount of charge is reduced or becomes zero, and it then enters the developer container 11 and a new developer 15 is bonded again to the drum.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a copying machine, a facsimile,
The present invention also relates to a developing device used in a printer or the like.

[0002]

2. Description of the Related Art FIG. 5 is a schematic side sectional view of a conventional developing device, in which reference numeral 1 denotes a photosensitive drum which is an image bearing member. Around the photoconductor drum 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged in this order in opposition thereto. The photosensitive drum 1 is rotationally driven in the direction of the arrow, the surface of the photosensitive drum 1 is charged by a charger 2, and the photosensitive drum 1 is exposed by an exposure device 3 in accordance with an image to be formed.
After the electrostatic latent image is formed, the developing device 4 attaches the developer to visualize it, and transfers the developer to the surface of the recording paper (not shown) or the like at a position facing the transfer device 5. After letting
The residual developer on the surface is removed by the cleaning device 6,
The above process is repeated again.

The developing device 4 has a length substantially equal to the axial length of the photosensitive drum 1 and a developer container 11 having an L-shaped cross section.
A developing roller 12 having appropriate elasticity is arranged facing the opening 11a in the above, and a developer supply roller 13 and an agitator 14 are arranged from the opening 11a toward the inner back side thereof, The developer 15 supplied into the container 11 is evenly distributed to the entire inside of the developer container 11 by the agitator 14, and the developer 15 is adhered to the developing roller 12 by the developer supply roller 13, and further, the developer roller. Twelve developers 15 are attached to the surface of the photosensitive drum 1.

A blade 16 which is in sliding contact with the peripheral surface of the developing roller 12 and charges the developer 15 on the upper surface of the opening 11a.
However, at the lower edge of the opening 11a, a developer leakage prevention tool 17
Are provided respectively. The blade 16 is in sliding contact with the peripheral surface of the developing roller 12 to charge the developer 15 adhering to the surface thereof so that the developer 15 can be reliably adhered to the peripheral surface of the photosensitive drum 1.

Next, the operation of such a conventional developing device will be described. In FIG. 5, the photosensitive drum 1 is charged on its entire surface at a position facing the charging device 2, and then exposed at a position facing the exposing device 3 to form an electrostatic latent image and facing the developing device 4. To do. In the developing device 4, a developer container
The developer 15 contained in 11 is agitated by the agitator 14 and uniformly dispersed in the entire longitudinal direction, and then adhered to the surface of the developing roller 12 by the developer supply roller 13.

The developing roller 12 is rotated in the direction of the arrow, and the surface of the developing roller 12 is slidably contacted by a blade 16 to charge the developer adhering to the surface to, for example, a positive pole or a negative pole. In the process of rolling contact with the photosensitive drum 1, the developer is attached to the surface of the photosensitive drum 1. Developing roller 12
Is again rotated to the developer supply region in the developer container 11 and the developer 15 is attached by the developer supply roller 13, and the above-described process is repeated. On the other hand, the photoconductor drum 1 to which the developer 15 is attached is visualized by the developer 15, and is developed on the surface of the recording paper passing between the photoconductor drum 1 and the transfer device 5 at a position facing the transfer device 5. Reversely attach the agent. The photoconductor drum 1 has a developer 15 remaining at a position facing the cleaning device 6.
After being removed, the above process is repeated again.

[0007]

By the way, if the developer 15 charged by the blade 16 is entirely transferred to the photoconductor drum 1 at a position facing the photoconductor drum 1, no problem occurs. 12 As it remains on the surface, a new developer 15 is again attached and charged by the blade 16, so the developer 15 newly attached and the development that is slid on the blade 16 many times. Agent
The difference in the amount of electrified charge between 15 and 15 is different, the amount of the developer 15 attached to the surface of the developing roller 12 is different, the amount of the developer attached to the surface of the photosensitive drum 1 is different, and uneven density occurs in the output image. There was a problem. The present invention has been made in view of the above circumstances, and an object of the present invention is to develop a developing device capable of developing without unevenness in light and shade by making the amount of developer supplied from a developing roller to a photosensitive member uniform. To provide.

[0008]

SUMMARY OF THE INVENTION A developing device according to the present invention rotates a photosensitive member holding an electrostatic latent image, a surface of the photosensitive member and a developer receiving region, and adheres to the surface. In a developing device equipped with a developing roller for adhering the developed developer to the surface of the photoconductor, in the middle of a rotation region in which the developing roller rotates from the position facing the photoconductor to the developer receiving region,
It is characterized in that a member for reducing or neutralizing the charge amount of the developer remaining on the surface of the developing roller is provided.

[0009]

According to the present invention, as a result, the developer remaining on the surface of the developing roller has its charge amount reduced or reduced to zero before a new developer is attached. The difference in the amount of electrified charge between the developer and the newly attached developer is reduced, and the developer can be uniformly supplied to the photoconductor to eliminate the uneven density of the output image.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic side sectional view of a developing device according to the present invention, in which reference numeral 1 denotes a photosensitive drum which is an image carrier. Around the photoconductor drum 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged in this order in opposition thereto. After the photosensitive drum 1 is rotationally driven in the direction of the arrow, the surface of the photosensitive drum 1 is charged by the charger 2, and then the photosensitive drum 1 is exposed corresponding to the image to be formed by the exposing device 3 to form an electrostatic latent image. After the developer 15 is made visible by the developing device 4, the developer 15 is transferred to the surface of the recording paper (not shown) or the like at a position facing the transfer device 5, and then the cleaning device 6 is operated. Then, the residual developer on the surface is removed, and the above process is repeated again.

The developing device 4 has a length substantially equal to the axial length of the photosensitive drum 1 and a developer container 11 having an L-shaped cross section.
Developing roller 12 having appropriate elasticity facing the opening 11a of
A developer supply roller 13 and an agitator 14 are provided from the opening 11a toward the inner back side thereof, and the developer 15 supplied into the developer container 11 is developed by the agitator 14 Evenly distributed throughout the container 11, and also the developer supply roller 13
The developer 15 is attached to the developing roller 12, and the developer roller 12 attaches the developer 15 to the surface of the photosensitive drum 1.

FIG. 2 is a plan view showing the combined state of the photosensitive drum 1 and the developing roller 12, and FIG. 3 is a partially enlarged perspective view of the same. The photosensitive drum 1 is attached to the shafts 1a protruding from both ends thereof. A flange portion 1c having an annular groove 1b is provided in the central portion. On the other hand, the developing roller 12 has a shaft 12b protruding from both ends thereof, and a flange portion of the photosensitive drum 1 attached to the shaft 12b.
A flange 12c having a thickness substantially equal to the width dimension of the annular groove 1b provided in 1c and larger than the diameter of the developing roller 12
Is provided, and the outer peripheral surface of the roller body 12a is brought into rolling contact with the photosensitive surface of the photosensitive drum 1 while the flange 12c is engaged in the annular groove 1b of the flange portion 1c.

As a result, the peripheral surfaces of the photosensitive drum 1 and the developing roller 12 are regulated so that their rotation centers are parallel to each other, and the peripheral surfaces thereof are in rolling contact with each other. The amount of developer adhered to the peripheral surface of No. 1 is made uniform, and uneven developer adherence is eliminated.

A blade 16 is provided on the upper edge of the opening 11a of the developer container 11 to charge the developer 15 on the surface of the developing roller 12 by sliding contact with the peripheral surface of the developing roller 12, and a developing blade is provided on the lower edge of the opening 11a. A leak preventing tool 17 for the agent 15 is provided respectively. Blade 16
Is configured to slide on the peripheral surface of the developing roller 12 to charge the developer 15 adhering to the surface of the developing roller 12 to ensure that the developer 15 adheres to the peripheral surface of the photosensitive drum 1.

FIG. 4 is a partially enlarged side view of the photoconductor drum 1, the developing roller 12, and the developer leakage preventive tool 17. The developer leakage preventive tool 17 is a ridge having an arc-shaped cross section provided at the lower edge of the opening 11a. A pressing member 17a having elasticity and a charge neutralizing member 17b are laminated and fixed on the surface of the portion 11b.
Then, the charge neutralizing member 17b is brought into sliding contact with the peripheral surface of the photosensitive drum 1 at an appropriate pressure so that the charge amount of the developer adhered to the surface of the photosensitive drum 1 is reduced or reduced to zero. There is. For example, when the developer 15 is negatively charged, for example, silicon is used as the material of the blade 16, and Teflon or the like is used as the charge neutralization member 17b. Reduce or neutralize.
When the developer 15 is charged to the positive pole, the materials of the blade 16 and the charge neutralizing member 17b may be reversed.

Next, the operation of the developing device according to the present invention will be described. The photosensitive drum 1 is rotationally driven in the arrow direction by a drive motor (not shown), and is charged on the entire circumferential surface at a position facing the charger 2, and an electrostatic latent image is formed on the surface at a position facing the exposure device 3. After being formed, a developer is formed at a position facing the developing device 4.
15 is attached and visualization is performed.

In the developing device 4, the developing roller 12, the developer supplying roller 13 and the agitator 14 are rotationally driven,
The developer in the developer container 11 is homogenized by the agitator 14 and then adhered to the peripheral surface of the developing roller 12 by the developer supply roller 13. When the developing roller 12 rotates, the developer 15 is rubbed by the blade 16 that is in sliding contact with the surface of the developing roller 12, and the developer 15 is charged to the positive pole or the negative pole. It is attached to the surface. Part of the developer 15 remaining on the surface of the developing roller 12 is a leakage preventive tool.
The charge neutralizing member 17b also serving as 17 is slidably contacted with the charge neutralizing member 17b to reduce or reduce the charge amount to zero, and then the developer container 11 is entered and a new developer 15 is attached again, and the above process is repeated. .

Developer adhering to the surface of the developing roller 12
Since the charge state of 15 is once neutralized or reduced at a position facing the charge neutralizing member 17b, the same charge as that of the newly attached developer 15 is charged and the remaining developer 15 is charged. The difference in charge amount between the new developer 15 and the new developer 15 is reduced, and the developer 15 is evenly attached to the photosensitive drum 1,
There is no shading in the image.

Further, the photosensitive drum 1 and the developing roller 12 are so arranged that their main body parts are in rolling contact with each other with the flange portion 12c of the developing roller 12 fitted in the annular groove 1b of the flange portion 1c of the photosensitive drum 1. Therefore, both of them are rotated with their rotation centers being constrained in a parallel state, and uneven density due to axis deviation is also suppressed.

[0020]

As described above, in the apparatus of the present invention, the developing roller is attached to the photoconductor because the neutralizing member is provided for reducing or reducing the charge amount of the developer adhered to the developing roller to zero. After the developer is attached, before the new developer is attached to the surface again, the charge amount of the residual developer is reduced or reduced to zero, and the developer is newly attached to the developing roller. The difference from the charge amount of the developer is reduced, and the problem that the developer is fixed to the developing roller is eliminated.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a developing device according to the present invention.

FIG. 2 is a schematic plan view showing a combined state of a photosensitive drum and a developing roller.

FIG. 3 is a partially enlarged perspective view showing a coupling portion between a photosensitive drum and a developing roller.

FIG. 4 is a partially enlarged view of a photosensitive drum, a developing roller and a charge neutralizing member.

FIG. 5 is a schematic side sectional view of a conventional developing device.

[Explanation of symbols]

 1 Photoconductor Drum 2 Charging Device 3 Exposure Device 4 Developing Device 5 Transfer Device 6 Cleaning Device 11 Developer Container 12 Developing Roller 13 Developer Supplying Roller 14 Agitator 15 Developer 16 Blade 17 Leakage Prevention Tool 17a Pressing Member 17b Charge Neutralizing Member

Claims (1)

[Claims] 1. A photoconductor that holds an electrostatic latent image, and a developing roller that rotates to face the surface of the photoconductor and a receiving area of the developer and attach the developer attached to the surface to the surface of the photoconductor. And a charge amount of the developer remaining on the surface of the developing roller in the middle of a rotation region where the developing roller rotates toward the developer receiving region from the position where the developing roller faces the photoconductor. A developing device provided with a member for reducing or neutralizing