JP2833524B2 - Developing device - Google Patents

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 suitable for an electrophotographic printing device.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. In this conventional example, a developing roller 51 for developing an electrostatic latent image on a photosensitive drum D, and a developing toner T
Supply roller 52 for supplying toner, a toner supply unit 53 for constantly supplying a predetermined amount of toner T to the toner supply roller 52, and a toner blade for setting the thickness of the toner layer on the developing roller 51 to an appropriate thickness. The developing device 50 includes a housing 54 and a housing 55 for housing and holding these components.

Further, a toner storage chamber 53A and a developing chamber 56 are provided inside the housing section 55, and these are communicated with each other via a supply port 55A. The toner T is filled in the toner storage chamber 53A, and the toner T is supplied from the toner supply port 55A to the developing chamber 56A.
Is provided with a toner mixer 53B to be fed to the side. The above-described toner replenishing section 53 is provided in the toner storage chamber 53A.
And a toner mixer 53B.

On the other hand, a developing roller 51, a toner supply roller 52, and a toner blade 54 are disposed inside the developing chamber 56. The toner blade 54 is protruded from the inside of the housing 55, and has a front end that is
The developing roller 51 is brought into contact with the outer peripheral surface of the developing roller 51 with a predetermined pressing force in a state facing the rotation direction of the developing roller 51. Reference numeral 57 denotes a seal member that prevents toner from leaking from below the developing roller 51.

In the conventional example, first, the toner T stored in the toner storage chamber 53A is sent from the supply port 55A to the developing chamber 56 by the rotation of the toner mixer 53B in the direction of arrow d. The toner T sent into the developing chamber 56 is
The toner is supplied from the toner supply roller 52 rotating in the direction of the arrow to the developing roller 51 rotating in the same direction.

Further, the toner T supplied to the developing roller 51 is thinned by the toner blade 54 and is triboelectrically charged at the same time. Then, by causing the developing roller 51 to face the photosensitive drum D with the thinned toner T attached, the electrostatic latent image formed on the photosensitive drum D is developed.

[0007]

Conventionally, a developing device has
If the developing operation is performed while the unused toner is sufficiently stored in the toner storing section, the amount of toner entering the developing chamber from the supply port by the toner mixer tends to increase. In such a case, the conventional developing device supplies the toner to the back of the contact surface of the toner blade with the developing roller,
This toner sometimes pressed the toner blade toward the developing roller. Then, due to this pressing, the toner blade cannot set the toner layer on the developing roller to a constant thickness.For example, the thickness of the toner layer on the developing roller is reduced, and the printed image is blurred. Alternatively, there is an inconvenience that a part of the image falls off white and print quality deteriorates.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing apparatus suitable for improving the image quality of a printing apparatus by solving the disadvantages of the conventional example.

[0009]

According to the first aspect of the present invention,
A developing roller that rotates in a predetermined direction for developing an electrostatic latent image on the photosensitive drum, a toner supply roller that supplies toner for development to the development roller, and a predetermined amount of toner that is constantly supplied to the toner supply roller A toner replenishing section, a toner blade for setting a thickness of a toner layer on the developing roller to an appropriate thickness, and a housing section for storing and holding each of the sections, and the toner blade has a front end formed on the developing roller. The toner blade is provided so as to be in contact with the developing roller in a direction opposite to the rotation direction, and both ends in the longitudinal direction of the toner blade are sealed with rubber or sponge in contact with the inner wall of the housing.

An opposing wall opposing a surface of the toner blade on the side of the toner replenishing portion is provided so as to project from the inside of the housing.
Both ends of the opposing wall are integrally brought into contact with the inner wall of the housing, and the front end of the opposing wall is brought close to the front end of the toner blade, and the sponge is uniformly in contact with the entire front end of the toner blade. Is provided at the tip of the opposing wall.

The invention according to claim 2 has the same structure as the invention according to claim 1, and has a tip of the toner blade.
However , it is bent toward the facing wall.

[0012]

According to the present invention, first, toner is supplied from the toner supply section to the toner supply roller. Then, toner for development is attached to the outer peripheral surface of the developing roller via the toner supply roller. The adhered toner is leveled by a toner blade into a layer having an appropriate thickness, and the rotation of the developing roller develops an electrostatic latent image previously formed on the outer peripheral surface of the photosensitive drum at a location facing the photosensitive drum. .

At this time, the toner blade has an opposing wall behind the contact surface with the photosensitive drum, and the toner blade and the opposing wall are fixed at one end to a housing part.
The unfixed end portions are uniformly in contact with each other via a seal member, and a space is formed between the toner blade and the opposing wall, where the toner does not enter.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The present embodiment is a developing device 10 that is provided in an electrophotographic printing apparatus and visualizes an electrostatic latent image formed on an outer peripheral surface of a photosensitive drum.

In this embodiment, a developing roller 1 rotating in a predetermined direction for developing an electrostatic latent image formed on the outer peripheral surface of a photosensitive drum D, and a developing toner T is supplied to the developing roller 1. A toner supply roller 2 and a toner supply unit 3 that constantly supplies a predetermined amount of toner T to the toner supply roller 2
A toner blade 4 for setting the thickness of the toner layer on the developing roller 1 to an appropriate thickness; an opposing wall 8 disposed opposite to the toner blade 4; and a housing for accommodating and holding these components. 5 is provided.

To describe each part in detail, first, the housing part 5 is a cartridge type container which is formed to be slightly wider than the photosensitive drum D and is detachable from the printing apparatus. Inside the housing 5, there are provided a toner storage section 3 </ b> A containing the toner T and a developing chamber 6 adjacent to the toner storage section 3 </ b> A and located on the photosensitive drum D side. The toner storage section 3A and the developing chamber 6 are separated by an internal wall disposed inside the housing section 5, and a supply port 5A is provided in the internal wall. The configuration is such that the section 3A and the developing chamber 6 communicate with each other.

The developing chamber 6 includes a developing roller 1, a toner supply roller 2, a toner blade 4 and an opposing wall 5, which will be described later.
And are arranged.

The developing roller 1 is a cylindrical member arranged in parallel with the center axis of the photosensitive drum D provided in the printing apparatus. The developing roller 1 has approximately the same length as the photosensitive drum D, and is rotatably supported by the housing 5. Further, the developing roller 1 is energized by a rotating force via an engaging portion (not shown) provided outside the housing portion 5 which engages with a driving source provided in the printing apparatus, and a developing operation is performed. At this time, the photosensitive drum D is rotated in the direction of arrow a in the figure, and is closely opposed to the photosensitive drum D in a state where the toner T supplied from the toner supply roller 2 is uniformly adhered on the outer peripheral surface. T
Is attached to the photosensitive drum D.

Adjacent to the developing roller 1, a toner supply roller 2 is provided in the housing 5. The toner supply roller 2 is a cylindrical member having substantially the same length as the developing roller 1 and is in contact with the outer peripheral surface of the developing roller 1 with a predetermined pressing force. The toner supply roller 2 is rotatably supported by the housing 5 and has an engaging portion (not shown) provided outside the housing 5 for engaging with a driving source provided in the printing apparatus. When the developing operation is performed, the toner T rotates in a direction indicated by an arrow b in the drawing, and causes the toner T supplied from the toner supply unit 3 to adhere to the developing roller 1. At this time, the toner supply roller 2 is rotating in the same direction as the developing roller 1 and is in contact with the developing roller 1 in a pressed state.
The toner T can be satisfactorily adhered to the toner.

A toner blade 4 is disposed above the developing roller 1 in a state where the toner blade 4 is implanted inside the housing 5. The toner blade 4 is used for the developing roller 1 described above.
And an end portion (hereinafter referred to as a front end portion) which is substantially opposite to the planting side on the outer peripheral surface of the developing roller 1.
Near the abutment.

As shown in FIG. 1, the toner blade 4 is disposed so as to face in the direction opposite to the rotation direction a of the developing roller 1, and faces the moving direction of the outer peripheral surface of the developing roller 1 during rotation. It is in a state. As a result, the toner T adhered on the outer peripheral surface of the developing roller 1 can be satisfactorily thinned.

The tip of the toner blade 4 is bent toward the toner replenishing portion 3 and uniformly contacts a seal member 9 provided at the tip of the opposite wall 8 described later. In addition, a sealing process is performed between both ends in the longitudinal direction of the toner blade 4 and the inside of the housing 5. More specifically, soft members such as rubber or sponge (not shown) are provided at both ends in the longitudinal direction of the toner blade 4, and are in contact with the inner wall of the housing unit 5 via the soft members. As a result, it is possible to effectively prevent the toner T from passing from both ends in the longitudinal direction of the toner blade 4.

An opposing wall 8 is provided on the side of the toner supply section 3 of the toner blade 4 in a state of being close to and opposing the toner blade 4. The opposing wall 8 protrudes downward from the inner wall of the housing unit 5 at a position above the toner supply roller 2, and both ends (both ends in the front and back directions of the paper surface of FIG. 1) correspond to the housing unit. 5 is integrally in contact with the inner wall.

The tip of the opposing wall 8 is close to the tip of the toner blade 4, and a seal member 9 is attached to the tip of the opposing wall 8 on the toner blade 4 side. The seal member 9 is made of a sponge material, is provided uniformly in the width direction of the opposing wall 8, and contacts the bent tip of the toner blade 4 as described above. With these structures, a closed small space is formed between the toner blade 4 and the opposing wall 8.

The toner replenishing section 3 comprises the above-mentioned toner storing section 3A and a toner mixer 3B disposed in the toner storing section 3A. The toner storing section 3A is a space formed to have a predetermined size, and the space T is filled with the toner T. As shown in FIG. 1, the toner storage section 3A has a substantially U-shaped cross section, and has a downwardly curved shape.

Further, the toner mixer 3B is composed of a rotating shaft located substantially at the center of the toner storage section 3A, and a stirring member rotating about the rotating shaft. Toner mixer 3
The rotation shaft of B is disposed in parallel with the developing roller 1 described above, and is rotatably supported by the housing 5. In addition, a rotational force is applied to the rotating shaft via an engaging portion (not shown) provided outside the housing portion 5 which engages with a driving source provided in the printing apparatus, and the rotating shaft is used during a developing operation. Is rotated in the direction of arrow d in the figure, and the stirring member is rotated accordingly, and the toner storage section 3A is rotated.
The toner inside is scooped up from the supply port 5A toward the developing chamber 6 so as to be scooped up.

Reference numeral 7 denotes a seal blade. The seal blade 7 has a function of scraping off toner remaining on the outer peripheral surface of the developing roller 1 after development on the photosensitive drum D. . In other words, the width of the seal blade 7 is set to be substantially equal to the width of the developing roller 1, and the end of the seal blade 7 that is in contact with the developing roller 1 is oriented in the same direction as the movement of the outer peripheral surface when the developing roller 1 rotates. , The toner T remaining on the outer peripheral surface of the developing roller 1 is effectively scraped off, and the toner T
Is housed inside the housing 5.

The operation of this embodiment will be described below with reference to FIG.

First, a rotational force is applied to the toner mixer 3B in the direction of arrow d, whereby the toner T in the toner storage section 3A is fed into the developing chamber 6 through the supply port 5A. The toner T sent into the developing chamber 6 from the supply port 5A
Is supplied onto the toner supply roller 2 and further sent from the toner supply roller 2 to the developing roller 1 side. At this time, the toner supply roller 2 and the developing roller 1 are rotating in the same direction, and the abutting portions of the toner supply roller 2 and the developing roller 1 are slid to perform the operation of attaching the toner T.

Then, with the rotation of the developing roller 1, the toner T adhered on the outer peripheral surface of the developing roller 1 reaches a contact portion between the toner blade 4 and the outer peripheral surface of the developing roller 1,
As it passes through this abutment, it is thinned and
It is triboelectrically charged.

Thereafter, the frictionally charged toner T passes through the contact portion with the toner blade 4 and is conveyed to a position close to and opposed to the photosensitive drum D, where the toner T is formed on the outer peripheral surface of the photosensitive drum D. The latent image is developed into a visible image.

The toner T remaining on the outer peripheral surface of the developing roller 1 after the development passes between the seal blade 7 and the contact by the rotation of the developing roller 1. At this time, the toner T remaining inside the housing 5 is scraped off by the seal blade 7. Thus, a series of development operations ends.

When the amount of the toner T in the toner storage section 3A is large, the amount of the toner T sent into the developing chamber 6 through the supply port by the rotation of the toner mixer 3B becomes excessive. If the excessive amount of the toner T is accumulated in the developing chamber 6 to a height reaching the toner blade 4, the opposite wall 8 provided on the toner supply unit 3 side of the toner blade 4 is used. Accordingly, it is possible to prevent the toner blade 4 from being pressed against the developing roller 1 by the toner T.

That is, the tip of the toner blade 4 and the opposing wall 8 are in contact with each other via the seal member 9, whereby the toner T
Since a closed small space is formed in which toner does not enter, it is possible to effectively prevent the toner blade 4 from being pressed toward the developing roller 1 by the toner T.

Since the tip of the toner blade 4 is bent toward the facing wall 8, the tip of the toner blade 4 comes into contact with a sealing member 9 provided at the tip of the facing wall 8 from the tip of the toner blade 4. It is possible to effectively prevent the toner T from entering the small space portion from the contact portions.

Further, since the sealing member 9 is attached to the tip of the opposing wall 8 on the side of the toner blade 4, the sealing member 9 comes into contact with the tip of the toner blade 4 from the front, and the small portions mentioned It is possible to effectively prevent the toner T from entering the space.

Further, since the sealing member 9 is formed of a sponge, when the tip of the toner blade 4 comes into contact with the sealing member, the tip of the toner blade 4 is stuck in the sealing member, and the toner T is more effectively prevented from entering. can do.

As described above, by equipping the printing apparatus with this embodiment, a toner layer is always formed with a constant thickness on the outer peripheral surface of the developing roller. Since the development is performed on the outer peripheral surface of the printing apparatus, the printing apparatus can improve the image quality.

[0039]

According to the present invention, an opposing wall is provided on the toner replenishing portion side of the toner blade, and the tips of the toner blade and the opposing wall are in contact with each other via a sealing member.
A small space in which toner does not enter can be formed on the toner supply section side of the toner blade. The small space prevents the toner blade from being pressed from the opposite side of the developing roller even when the amount of toner inside the toner replenishing unit is large and excessively supplied.

Thus, the toner blade removes the pressing force of the toner from behind, and can maintain the state in which the toner blade is in contact with the developing roller with a more stable pressing force than in the related art. A toner layer is formed on the surface with a thickness that is more stable than before, and accordingly, development can be performed on the outer peripheral surface of the photosensitive drum D with a fixed amount of toner.
Further, by equipping the printing apparatus with the present invention, it is possible to maintain a more stable print density than before and improve image quality.

When the tip of the toner blade is bent toward the facing wall, the tip of the toner blade comes into contact with a sealing member provided at the tip of the facing wall from the tip of the toner blade. In order to effectively prevent the toner from entering the small space portion, it is possible to further effectively prevent the toner blade from being pressed against the developing roller by the toner.

Further, when the sealing member is formed of sponge, when the tip of the toner blade comes into contact with the sponge, the tip of the toner blade is stuck in the sponge, and the toner is more effectively prevented from entering the small space. Further, it is possible to effectively prevent the toner blade from being pressed against the developing roller by the toner.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one embodiment of the present invention.

FIG. 2 is a schematic sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Development roller 2 Toner supply roller 3 Toner supply part 4 Toner blade 5 Housing part 8 Opposing wall 9 Sponge (seal member) 10 Developing device D Photosensitive drum T Toner

Claims (2)

(57) [Claims] A developing roller that rotates in a predetermined direction for developing an electrostatic latent image on a photosensitive drum; a toner supply roller that supplies toner for development to the development roller; A toner replenishing unit that constantly replenishes toner, a toner blade that sets the thickness of the toner layer on the developing roller to an appropriate thickness, and a housing unit that stores and holds these components. A developing device equipped with a front end thereof in a direction facing the rotation direction of the developing roller and abutting against the developing roller, wherein both ends in the longitudinal direction of the toner blade are attached to an inner wall of the housing portion. Sealing with rubber or sponge in contact with each other, and opposing walls opposing a surface of the toner blade on the toner replenishing portion side protruding from the inside of the housing, and both ends of the opposing wall. A sealing member made of a sponge, which is integrally brought into contact with the inner wall of the housing, makes the tip of the opposing wall close to the tip of the toner blade, and uniformly contacts the entire tip of the toner blade. A developing device, wherein the developing device is provided at a tip of an opposing wall. 2. The developing device according to claim 1, wherein a tip of said toner blade is bent toward said opposed wall.