JPH08129302A - Developing device - Google Patents

Abstract

PURPOSE: To improve image quality by making the length from a supporting member to a developer carrier in both end parts in the width direction of the elastic member of a regulating member regulating the thickness of a developer shorter than that in the central part in the width direction. CONSTITUTION: The regulating member 26 for regulating the thickness of toner stuck to the surface of a developing roller 20 includes a plate-like elastic member 32 and the supporting member 34 supporting the elastic member 32 and having an L-shaped cross-sectional path. The supporting member 34 includes a fixing part 44 for fixing the elastic member 32 on a housing and an energizing part 46 energizing the elastic member 32. The energizing part 46 is formed with a curved bottom surface and when the elastic member 32 is supported by the supporting member 34, the length (effective length) L1 from the supporting member 34 to the developing roller 20 in both end parts in the width direction of the elastic member 32 is made shorter than the effective length L2 in the central part in the width direction. Thus, the press-contact force of the abutting part 36 of the elastic member 32 with the developing roller 20 is made uniform over the entire length in the width direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a developing device incorporated in, for example, a copying machine, a printer or a facsimile to develop an electrostatic latent image formed on the surface of a photoconductor with a developer.

[0002]

2. Description of the Related Art A conventional developing device 1 of this type shown in FIG.
Includes a housing 3 that houses the developer 2 therein. The opening 4 is formed on the side surface of the housing 3, and the opening 4
Is provided with a developing roller 6 for supplying the developer 2 to the photoconductor drum 5, and above the opening 4, the thickness of the developer 2 attached to the surface of the developing roller 6 is regulated. A regulating member 7 is provided. As shown in FIG. 8, the regulating member 7 is a plate-shaped elastic member 8 made of metal such as stainless steel.
Further, the support member 9 for supporting the elastic member 8 above the opening 4 is included, and the lower end surface of the support member 9 is formed horizontally. Therefore, the length from the regulating member 9 to the developing roller 6 is uniform in the width direction of the elastic member 8.

[0003]

In the prior art, since the length from the supporting member 9 to the developing roller 6 is made uniform in the width direction of the elastic member 8, the pressure contact force of the elastic member 8 to the developing roller 6 is made. Was smaller at both widthwise end portions than at the widthwise central portion of the elastic member 8. Therefore, the developing roller 6
There is a problem that the thickness of the developer layer formed on the surface in the width direction of the toner is uneven, and a high quality image cannot be obtained.

Therefore, a main object of the present invention is to provide a developing device capable of improving image quality.

[0005]

SUMMARY OF THE INVENTION The present invention is a developer for developing an electrostatic latent image formed on the surface of a photoconductor, the developer being attached to the surface of the photoconductor. In a developing device including a carrier and a regulating member that regulates the thickness of the developer adhered to the surface of the developer carrier, the regulating member has one end in the length direction or the vicinity thereof pressed against the surface of the developer carrier. A plate-shaped elastic member and a support member that supports the other end of the elastic member in the length direction or the vicinity thereof, and the length from the support member to both ends of the elastic member in the width direction to the developer carrying member. Is made shorter than that in the central portion in the width direction, so that the pressure contact force of the elastic member with respect to the developer carrying member is made uniform over the entire length in the width direction of the elastic member.

[0006]

The thickness of the developer adhering to the surface of the developer carrier is regulated by the regulating member. The regulating member includes an elastic member and a supporting member. One end in the lengthwise direction of the elastic member or its vicinity is pressed against the surface of the developer carrier, and the other end in the lengthwise direction of the elastic member or its vicinity is supported by the supporting member. To be done.
Since the length from the supporting member to the developer carrying member at both widthwise end portions of the elastic member is shorter than that at the widthwise central portion, the pressure contact force of the elastic member against the developer carrying member is the width of the elastic member. It can be held uniformly over the entire length of the direction.

[0007]

EFFECTS OF THE INVENTION Since it is possible to prevent unevenness in the thickness of the developer layer formed on the surface of the developer carrying member, it is possible to improve the image quality. The above objects of the present invention, other objects,
Features and advantages will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing device 10 of this embodiment shown in FIG. 1 has an electrostatic latent image formed on the surface of a photosensitive drum (photosensitive plate, photosensitive belt or the like) 12 which is an electrostatic latent image carrier. The toner 14 is attached to form a visible image, and includes a housing 16 that accommodates the toner 14 therein. An opening 18 is formed on a side surface of the housing 16, and a developing roller 20 and a developing roller 20 for contacting the photosensitive drum 12 and supplying the toner 14 to the photosensitive drum 12 are provided inside the housing 16 and near the opening 18. A supply roller 22 for supplying the toner 14 is provided. Further, in the center of the inside of the housing 16, an agitator 24 for stirring the toner 14 and supplying the toner 14 to the supply roller 22 is provided.
Is provided. When the negative-polarity toner 14 is used as the material of the developing roller 20, the toner 14 is formed on a triboelectric charging series such as urethane.
When a positive polarity toner 14 is used, a material which is more negative than the toner 14 on the triboelectric charging series such as a CR rubber sponge is used.

A regulating member 26 for regulating the thickness of the toner 14 adhering to the surface of the developing roller 20 and the toner 1 passing through the regulating member 26 are provided above the opening 18.
A shield member 28 is attached by a mounting screw 40 to prevent the flying of the toner particles 4 onto the non-latent image portion of the photosensitive drum 12. Further, below the opening 18, the opening 1
8 from the gap between the inner surface of the lower part of 8 and the developing roller 20.
Toner leakage prevention member 30 for preventing toner from leaking
Is provided.

As shown in FIG. 2, the regulating member 26 includes a plate-like elastic member 32 made of, for example, stainless steel or phosphor bronze, and a supporting member 34 having a substantially L-shaped cross section for supporting the elastic member 32. An abutting portion 36 that abuts the developing roller 20 by smoothly finishing the edge portion is formed at one end (lower end) in the length direction of the elastic member 32, and the elastic member 32 is provided at the other end (upper end) in the length direction. A mounting portion 38 for mounting the elastic member 32 to the housing 16 is formed by bending itself at a right angle. A plurality of holes (four in this embodiment) 42 for passing the mounting screws 40 are formed in the mounting portion 38.

On the other hand, the supporting member 34 urges the elastic member 32 so that the fixing portion 44 for fixing the elastic member 32 to the housing 16 and the elastic member 32 (contact portion 36) can be pressed against the developing roller 20. A hole (not shown) corresponding to the hole 42 of the elastic member 32 is formed in the fixed portion 44, including the biasing portion 46 that operates. The urging portion 46 is formed such that the lower end surface thereof is curved so that the length in the center portion in the width direction is shorter than the length in both end portions in the width direction. Therefore, when the elastic member 32 is supported by the support member 34, the elastic member 32
From the supporting member 34 at both ends in the width direction of the developing roller 2
The length L ₁ up to 0 (hereinafter referred to as “effective length”) L ₁ becomes longer than the effective length L ₂ at the center portion in the width direction, and the elastic member 32 (contact portion 36) is pressed against the developing roller 20. The force is made uniform over the entire length in the width direction.

The shielding member 28 is made of urethane rubber, silicon rubber, stainless steel, phosphor bronze or the like in a plate shape or a sheet shape, and one end (lower end) of the shielding member 28 is in the vicinity of a contact portion between the developing roller 20 and the photosensitive drum 12. The other end (upper end) is fixed to the elastic member 32 so as to be located at.
Therefore, the elastic member 32, the developing roller 20, and the shielding member 28 form a closed space A (FIG. 3).

The developing device 10 as described above is mounted in an image forming apparatus such as a copying machine, a printer or a facsimile, and the developing roller 20 is pressed against the photosensitive drum 12 with a predetermined pressure by a pressing device (not shown) (see FIG. 1). Thereby, an appropriate developing nip is maintained in the developing area B (FIG. 3). Around the photoconductor drum 12, a charger 48 for uniformly charging the surface of the photoconductor drum 12,
A light image irradiating means 50 for irradiating a light image on the surface of the photosensitive drum 12 to form an electrostatic latent image, a transfer device 52 for transferring the toner image developed by the developing device 10 to a sheet (not shown), and A cleaning device 54 for removing the toner 14 remaining on the surface of the photoconductor drum 12 is arranged in this order from the upstream side in the rotation direction of the photoconductor drum 12, and the developing roller 20 is on the downstream side of the light image irradiation means 50. Is arranged on the upstream side of the transfer device 52.

The developing device 10 can be applied to both a reversal development process in a printer or the like and a normal rotation development process in a copying machine or the like.
The reversal development process using the developing device 10 will be described. However, here, a negatively charged organic photosensitive drum is used as the photosensitive drum 12, and a negative polarity toner is used as the toner 14.

The developing roller 2 is driven by a motor (not shown).
0, the supply roller 22 and the agitator 24 are rotated in the arrow direction (FIG. 1), the toner 1 in the housing 16
4 is agitated by the agitator 24 and supplied to the supply roller 22. The toner 14 supplied to the supply roller 22 is negatively charged by frictional charging with the supply roller 22 or the developing roller 20, and then adheres to the surface of the developing roller 20. The toner 14 attached to the surface of the developing roller 20 is removed by the developing roller 20 and the regulating member 26.
At the contact portion C (FIG. 3) with the (elastic member 32), the thickness is regulated by the elastic member 32, and the toner is frictionally charged again. At this time, as described above, since the pressure contact force of the elastic member 32 to the developing roller 20 is made uniform over the entire width direction, the toner 1 thinned at the contact portion C is formed.
The thickness of 4 can be made uniform over the entire length in the width direction. The toner 14 thinned in the contact portion C and charged to a predetermined potential is conveyed to the developing area B as the developing roller 20 rotates. If uncharged or reverse polarity toner 14 'is present on the surface of the developing roller 20 during this conveyance process, the toner 14' may fly into the space A, but the space A is closed by the shielding member 28. Therefore, the problem that the flying toner 14 'adheres to the surface (non-latent image portion) of the photosensitive drum 12 outside the developing area B does not occur.

On the other hand, the photoconductor drum 1 is charged by the charger 48.
The surface of the photosensitive drum 12 is uniformly charged, and the surface of the photoconductor drum 12 is exposed by the light image irradiation means 50 to form an electrostatic latent image on the exposed portion. Then, this electrostatic latent image is developed with toner 14 on the surface of the developing roller 20 in the developing area B. Uncharged or reverse polarity toner 14 '
In the developing area B, due to friction between the developing roller 20 and the photoconductor drum 12, the toner is charged to an appropriate charging polarity (negative polarity). The toner image thus formed on the surface of the photoconductor drum 12 is transferred onto a sheet (not shown) by the transfer device 52, and the toner 14 remaining on the surface of the photoconductor drum 12 is removed by the cleaning device 54. Further, the toner 14 not used for the development in this developing step is returned to the inside of the housing 16 again, and scraped off by the supply roller 22 which contacts the developing roller 20 and rotates.

According to this embodiment, the lower end surface of the urging portion 46 of the support member 34 (FIG. 2) is formed to be curved, and the effective length L ₁ at both widthwise ends of the elastic member 32 is set to the widthwise center. By making it shorter than the effective length L _{2 in the} portion, the pressure contact force of the elastic member 32 (contact portion 36) to the developing roller 20 is made uniform over the entire length in the width direction. The thickness of the toner 14 thus formed can be made uniform, so that the image quality can be improved.

Further, since the toner 14 'which has been blown off by the shielding member 28 can be prevented from adhering to the non-latent image portion of the photosensitive drum 12, so-called "fog" can be prevented from occurring on the output image. Although the lower end surface of the urging portion 46 of the support member 34 is formed to be curved in the above-described embodiment, the urging portion 4 is formed as shown in FIG. 4, for example.
The lower end surface of 6 may be provided with a step, or the lower end surface of the biasing portion 46 may be formed in a V shape as shown in FIG. 5, for example. Even in these cases, the elastic member 32
Since the effective length L ₁ at both ends in the width direction can be made shorter than the effective length L ₂ at the center in the width direction,
The pressure contact force of the elastic member 32 (contact portion 36) to the developing roller 20 can be made uniform over the entire length in the width direction, so that the image quality can be improved.

Further, in the above embodiment, the case where the so-called reverse pressure contact type regulating member 26 in which the free end of the elastic member 32 is located on the upstream side in the rotation direction of the developing roller 20 with respect to the fixed end is used. However, in the present invention, as shown in FIG. 6, for example, when a so-called forward pressure contact type regulating member 26 in which the free end of the elastic member 32 is located on the downstream side in the rotation direction of the developing roller 20 with respect to the fixed end is used. Can be similarly applied to.

When the forward pressure contact type restricting member 26 is used, as shown in FIG.
The shielding member 56 made of a material such as silicone, nylon, etc., which has a friction coefficient with the toner 14 larger than the friction coefficient between the elastic member 32 and the toner 14 (preferably the friction coefficient between the toners 14) and has excellent wear resistance. May be fixed to the lower surface of the elastic member 32, and may be interposed between the developing roller 20 and the elastic member 32 in the contact portion C. When such a shielding member 56 is used, friction between the regulating member 26 (shielding member 56) and the toner 14 at the contact portion C increases, so that the pressure contact force of the elastic member 32 with the developing roller 20 can be reduced. Therefore, even when the developing roller 20 is not used for a long period of time, the problem that the developing roller 20 is deformed by the pressure contact force of the elastic member 32 does not occur.

Further, in the above embodiment, the elastic member 32 is used.
Although the edge portion (contact portion 36) is pressed against the developing roller 20, the abdomen of the elastic member 32 may be pressed against the developing roller 20 instead. Even in this case, the length from the support member 34 to the developing roller 20 is the effective length of the elastic member 32.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is a perspective view showing a regulating member used in the embodiment of FIG.

FIG. 3 is an illustrative view showing a state in which a toner layer is formed on the surface of a developing roller.

FIG. 4 is a perspective view showing a modified example of the restriction member.

FIG. 5 is a perspective view showing a modified example of the restriction member.

FIG. 6 is a perspective view showing a modified example of the restriction member and the shielding member.

FIG. 7 is an illustrative view showing a conventional technique.

FIG. 8 is a perspective view showing a restricting member in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Developing device 12 ... Photosensitive drum 14 ... Toner 16 ... Housing 20 ... Developing roller 26 ... Regulation member 28 ... Shielding member 32 ... Elastic member 34 ... Supporting member 46 ... Energizing portion

Claims (1)

[Claims] 1. A developer carrier for developing an electrostatic latent image formed on the surface of a photoconductor, the developer carrying body depositing the developer adhered to the surface to the photoconductor, and the developer. In a developing device including a regulating member that regulates the thickness of the developer attached to the surface of the carrier, the regulating member has a plate whose one end in the length direction or the vicinity thereof is pressed against the surface of the developer carrier. Elastic member,
A support member that supports the other end of the elastic member in the length direction or the vicinity thereof, and the width from both ends of the elastic member in the width direction to the developer carrying member is the width direction central portion. The developing device is characterized in that the pressure contact force of the elastic member with respect to the developer carrying member is made uniform over the entire length in the width direction of the elastic member by making it shorter than that.