JPH08129301A - Developing device - Google Patents

Abstract

PURPOSE: To stably obtain a high quality image by keeping the thickness of a toner layer formed on the surface of a developing roller optimum. CONSTITUTION: When the developing roller 24 is rotated, toner 14 stuck on the surface of the developing roller 24 is carried toward the contact part B of the developing roller 24 with a blade 30. At this time, the quantity of the toner 14 supplied to a wedge-shaped space C is regulated by a projecting part 34 projectingly formed on the under surface side of an elastic member 32. Thus, the lifting up of the blade 30 (elastic member 32) caused by the pressure rise of the toner 14 in the space C can be prevented.

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 for developing an electrostatic latent image formed on a surface of a photoconductor using a developer.

[0002]

2. Description of the Related Art With reference to FIG. 8, in a conventional developing device 1, one end of a metal blade 2 is fixed to a developing tank 3 and the other end is elastically pressed against the surface of a developing roller 4, whereby The thickness of the developer 5 attached to the surface of the developing roller 4 is regulated.

[0003]

In the conventional developing device 1, the wedge-shaped space 6 formed by the blade 2 and the developing roller 4 is wide open toward the inside of the developing tank 3, so that the space 6 is formed. The developer 5 may be excessively supplied. When the developer 5 is excessively supplied to the space 6, the pressure of the developer 5 in the space 6 increases and the blade 2 is lifted, and the thickness of the developer layer formed on the surface of the developing roller 4. However, there is a problem that the image quality is deteriorated due to the increase in thickness.

There is also a problem that the developer 5 is fused to the blade 2 in the vicinity of the contact portion between the blade 2 and the developing roller 4 and the thickness of the developer layer becomes uneven. Therefore, a main object of the present invention is to provide a developing device capable of preventing deterioration of image quality.

[0005]

SUMMARY OF THE INVENTION The present invention is for developing an electrostatic latent image formed on the surface of a photoreceptor with a developer, and a developing tank containing the developer therein. In a developing device including a developer carrier for supplying the developer adhered to the surface of the photoreceptor to the photosensitive member, and a blade for regulating the thickness of the developer adhered to the surface of the developer carrier, the blade is a developer carrier. A plate-shaped elastic member pressed against the surface of the body, and a protrusion provided on one main surface of the elastic member so as to regulate the amount of the developer conveyed to the contact portion between the elastic member and the developer carrier. And a developing unit.

[0006]

The amount of the developer conveyed to the contact portion between the elastic member and the developer carrying member is regulated by the protrusion provided on the one main surface of the elastic member, so that the blade (elastic member) It is possible to prevent the developer from being excessively supplied to the wedge-shaped space formed by the developer carrier. Therefore, it is possible to prevent the thickness of the developer layer formed on the surface of the developer carrier from increasing due to the elastic member being lifted by the pressure of the developer. Further, it is possible to prevent the developer from being fused to the elastic member in the vicinity of the contact portion between the elastic member and the developer carrying member.

[0007]

According to the present invention, deterioration of image quality can be prevented. The above-mentioned objects, other objects, features and advantages of the present invention 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 one component for a 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 that is a developer is attached to form a visible image, and includes a housing 16. An accommodating container 18 for accommodating the toner 14 is disposed on the upper portion of the housing 16, and a developing tank 22 having an opening 20 on the lower side surface thereof is formed inside the housing 16 and below the accommodating container 18. A developing roller 24 as a developer bearing member for contacting the photosensitive drum 12 and supplying the toner 14 to the photosensitive drum 12 is disposed in the opening 20, and inside the developing tank 22, from the container 18 to the developing tank 22. A supply roller 26 for supplying the toner 14 supplied to the developing roller 24 is arranged.
Further, a voltage applying device 28 is connected to the developing roller 24. A blade 30 for regulating the thickness of the toner 14 attached to the surface of the developing roller 24 is provided above the opening 20.

As shown in FIG. 2, the blade 30 includes a plate-shaped elastic member 32 made of metal such as stainless steel or phosphor bronze, and the elastic member 32 is provided on one main surface (lower surface) of the elastic member 32. The protrusion 34 is formed by bending itself. In addition, the protrusion 34 of the elastic member 32
The portion 36 closer to the free end is formed so as to gradually become thinner toward the free end. The other end (fixed end) of the elastic member 32 is fixed to the housing 16 (FIG. 1) so that one end (free end) of the elastic member 32 elastically comes into pressure contact with the surface of the developing roller 24.

The developing device 10 is mounted in an image forming apparatus such as a copying machine or a printer, and the pressing device 38 presses the developing roller 24 against the photosensitive drum 12 with a force of about 1 to 3 kgf. A proper developing nip (1-2 mm) is maintained in the developing area A. A charging device 40, a cleaning device 42, and the like are arranged around the photosensitive drum 12.

The developing device 10 can be applied to both the reversal development process in a printer or the like and the forward development process in a copying machine or the like.
The reversal development process using the developing device 10 will be described. The photosensitive drum 12 and the toner 14 may be either positively charged or negatively charged.
In this embodiment, a positively charged organic photosensitive drum is used as the photosensitive drum 12, and a positively charged non-magnetic toner containing styrene-acrylic resin as a main component is used as the toner 14.

When the developing roller 24 and the supply roller 26 are rotated in the arrow direction by driving a motor (not shown), the toner 14 is supplied to the developing roller 24 by the supply roller 26. At this time, frictional charging occurs between the toner 14 and the supply roller 26 and the developing roller 24, and the toner 14 is positively charged. Here, when the supply roller 26 is made of a conductive material such as a metal shaft on which conductive urethane foam is laminated, it is possible to prevent the charging performance of the toner 14 from being deteriorated due to overcharge of the supply roller 26. The toner 14 supplied to the developing roller 24 is electrostatically adsorbed on the surface of the developing roller 24,
As the developing roller 24 rotates, the developing roller 24 is conveyed toward the contact portion B between the developing roller 24 and the blade 30 (elastic member 32). At this time, the amount of the toner 14 supplied into the wedge-shaped space C (FIG. 2) formed by the developing roller 24 and the blade 30 (elastic member 32) is regulated by the protrusion 34.

The toner 14 conveyed to the contact portion B is regulated in thickness by the blade 30 (elastic member 32) so as to have a thin layer (10 to 30 μm) and is again charged by friction. Then, the thinned toner 14 is conveyed toward the developing area A as the photosensitive drum 24 rotates. On the other hand, the surface potential of the photosensitive drum 12 is maintained at +700 V by the charging device 40, the surface of the photosensitive drum 12 is exposed by an optical writer (not shown), and an electrostatic latent image is formed on the exposed portion. The electrostatic latent image is toner-developed in the developing area A by the toner 14 attached to the surface of the developing roller 24. At this time, the developing roller 24 is
A developing bias voltage of +300 V is applied by the voltage applying device 28.

According to this embodiment, it is possible to prevent the toner 14 from being excessively supplied to the wedge-shaped space C by the protrusion 34 (FIG. 2), so that the pressure of the toner 14 in the space C increases and the elastic member. 32 can be prevented from being lifted, and the thickness of the toner 14 conveyed to the developing area A can be prevented from increasing. In addition, the elastic member 3 near the contact portion B
It is possible to prevent the toner 14 from being fused to the second toner. Therefore, a high quality image can be stably obtained.

In the embodiment described above, the blade 30 having the projection 34 formed by bending the elastic member 32 itself is used, but such a blade 3 is used.
Instead of 0, the blades 44, 46, 4 as shown below
8, 50 or 52 (FIGS. 3 to 7) or the like may be used. The blade 44 shown in FIG. 3 has a developer amount regulating member (hereinafter, referred to as “regulating member”) 56 having a regulating surface 54 for regulating the amount of the toner 14 conveyed to the contact portion B on the lower surface of the elastic member 32. Is fixed.

The blade 46 shown in FIG. 4 has a regulating member 58 having a regulating surface 54 and an elastic member 3 having a friction coefficient with the toner 14 such as urethane, silicon, nylon or the like.
2 and the toner 14 (preferably the friction coefficient between the toners 14) and is made of a material having excellent wear resistance, and a part of the material is formed in the contact portion B between the elastic member 32 and the developing roller 24. It is intervened between. According to this blade 46, since the thin layer of the toner 14 is formed by using the regulating member 58 having a large friction coefficient with the toner 14, the pressure contact force of the elastic member 32 to the developing roller 24 can be reduced, and therefore, Even when the developing roller 24 is not used for a long period of time, the problem that the developing roller 24 is deformed by the pressure contact force of the elastic member 32 does not occur.

In the blade 48 shown in FIG. 5, the end portion of the regulating member 58 in the blade 46 shown in FIG.
No. 2 is projected forward from the free end, and the thickness of the tip portion is formed thin. According to this blade 48, since the thickness of the tip portion thereof is extremely thin, it is possible to prevent the toner 14 from adhering to the tip portion and to prevent the image from being disturbed due to toner scattering or the like.

The blade 50 shown in FIG. 6 has a friction coefficient with the toner 14 such as urethane rubber which is larger than the friction coefficient between the elastic member 32 and the toner 14 (preferably the friction coefficient between the toners 14) and has a high resistance. It includes a substantially plate-shaped elastic member 60 made of a material having excellent wear resistance. A projecting portion 63 having a substantially triangular cross section having a regulation surface 62 for regulating the amount of the toner 14 conveyed to the contact portion B is integrally formed at the free end side end portion of the elastic member 60. The lower surface of the developing roller 2
Pressed to No. 4. With this blade 50, the pressure contact force of the elastic member 60 against the developing roller 24 can be reduced similarly to the blade 46 or 48 shown in FIG. 4 or 5.

In the blade 52 shown in FIG. 7, the free end side end of the elastic member 60 in the blade 50 shown in FIG. 6 is projected beyond the contact portion B, and the thickness of the end portion is thin (0.1 mm). It was formed. According to this blade 52, the pressing force of the elastic member 60 against the developing roller 24 can be reduced similarly to the blade 46, 48 or 50 shown in FIG. 4, 5 or 6, and the blade 48 shown in FIG. Similarly, it is possible to prevent the toner 14 from adhering to the tip of the blade 60.

[Brief description of drawings]

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

FIG. 2 is an illustrative view showing a blade used in the embodiment in FIG.

FIG. 3 is an illustrative view showing a modified example of a blade.

FIG. 4 is an illustrative view showing a modified example of a blade.

FIG. 5 is an illustrative view showing a modified example of a blade.

FIG. 6 is an illustrative view showing a modified example of a blade.

FIG. 7 is an illustrative view showing a modified example of the blade.

FIG. 8 is an illustrative view showing a conventional technique.

[Explanation of symbols]

 10 ... Developing device 12 ... Photosensitive drum 14 ... Toner 24 ... Developing roller 30, 44, 46, 48, 50, 52 ... Blade 32, 60 ... Elastic member 34, 63 ... Projection 56, 58 ... Developer amount regulating member

Claims (6)

[Claims] 1. A developing tank for developing an electrostatic latent image formed on a surface of a photoconductor with a developer, the developing tank containing the developer therein, and the developing tank adhered to the surface thereof. In a developing device including a developer carrying member that supplies a developer to the photosensitive member, and a blade that regulates the thickness of the developer attached to the surface of the developer carrying member, the blade is the developer carrying member. A plate-shaped elastic member pressed against the surface of the elastic member, and protruding to one main surface of the elastic member so as to regulate the amount of the developer conveyed to the contact portion between the elastic member and the developer carrying member. A developing device, comprising: a protrusion provided. 2. The developing device according to claim 1, wherein the protrusion is provided integrally with the elastic member by bending the elastic member. 3. The developing device according to claim 1, wherein the elastic member has a thin free end protruding forward from the contact portion by a predetermined length. 4. The developing device according to claim 1, wherein the protrusion includes a developer amount regulating member fixed to the one main surface of the elastic member. 5. A friction coefficient of the developer amount regulating member with the developer is set to be larger than a friction coefficient of the elastic member with the developer, and the friction coefficient is set between the elastic member and the developer carrying member. The developing device according to claim 4, wherein the developer amount regulating member is interposed. 6. The elastic member according to claim 4, wherein the elastic member has a free end, and the developer amount restricting member has a thin-walled portion protruding forward from the free end by a predetermined length. Development device.