JPH11161010A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a developing device stably/excellently carry out the form a thin layer of a developer for a developer carrier at all times and to carry out the development without unevenness by providing a developer infiltration preventing member for preventing the infiltration of the developer to the side of the surface without being brought into contact with the developer carrier of a developer regulating member, between it and a developer chamber frame. SOLUTION: An elastic sheet member 7 is fixed as a developer infiltration preventing member, in the whole area in the longitudinal direction of the part of a developing chamber frame 1, corresponding to the upper part of an elastic blade member 3 as a developer regulating member and hung toward the top end part 3b of the elastic blade member 3 to make a space part S a closed state. Since the elastic sheet member 7 as the developer preventing member exists, the infiltration of a toner into the space part S between the blade member 3 and the part of the developing chamber frame 1 present on the blade member 3 is prevented. The length of the elastic sheet member 7 is set longer than that of the top end part 3b of the blade member 3, when the elastic sheet member 7 and the top end part 3b are brought into contact with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic process or an electrostatic recording process, and a method for forming an electrostatic image formed on the surface of an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric by toner. The present invention relates to a developing device for developing.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed and put into practical use as a developing device of a dry type one-component developing system.

In recent years, in small copiers and the like, an elastic member such as a rubber plate or a metal plate as a developer regulating member is brought into contact with a rotating sleeve (developing sleeve) as a developer carrying member, and the contact portion is used. It regulates the amount of toner as a developer on the sleeve, triboelectrically charges it, and then, under the action of a magnetic field,
A developing method (elastic blade coat system development) of developing the electrostatic image on the surface of the image bearing member with toner in a very close proximity to the image bearing member on which the electrostatic image is formed and facing the image bearing member without contact is used.

FIG. 4 shows an example of such a developing device. A is the overall reference number of the developing device, 1 is a developer chamber frame (developer container frame), and 2 is a developer as a developer carrier, which is disposed inside the developer chamber frame 1 with its side exposed to the outside. The sleeve is driven to rotate at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow. Although not shown in the figure, a magnet roller as a magnetic field generating means is inserted and arranged in the developing sleeve 2, and a predetermined developing bias is applied to the developing sleeve 2 from a power supply unit (not shown).

Reference numeral 3 denotes an elastic blade member such as a rubber plate or a metal plate as a developer regulating member. This blade member 3
Above the developing sleeve 2, the base side 3 a is fixedly supported by the developer chamber frame 1 (upper container part), and the front end side 3 b
Is extended into the developer chamber to be counter-positioned in the rotation direction of the developing sleeve 2 so as to bend against the upper surface of the developing sleeve against elasticity and abut against the upper surface of the developing sleeve. Resiliently. 4 is a contact part.

Reference numeral 5 denotes a developer stirring member disposed in the developer chamber, which is rotationally driven clockwise by an arrow at a predetermined peripheral speed by a drive system (not shown).

Reference numeral 6 denotes a toner as a developer contained in the developer chamber, which is agitated by the rotation of the developer agitating member 5, conveyed in the direction of the developing sleeve 2, and supplied to the developing sleeve 2.

Reference numeral B denotes a rotary drum type image carrier, for example, an electrophotographic photosensitive drum, which is rotated at a predetermined peripheral speed in a clockwise direction indicated by an arrow. A process device for forming an electrostatic image of image information on the drum B is provided.
It is omitted in the figure.

The developing device A is disposed with the developing sleeve 2 approaching a drum B as an image carrier with a predetermined small gap.

The thickness of the toner supplied to the rotating developing sleeve 2 is regulated by a contact portion 4 between the developing sleeve 2 and a blade member 3 serving as a developer regulating member. As a coat. It is also triboelectrically charged.

The thin toner layer 5a is conveyed to a developing portion which is a portion of the drum B and the developing sleeve 2 which is in close proximity to each other by the subsequent rotation of the developing sleeve 2. Selectively moves to the drum B side in response to the electrostatic image under the action of the magnetic field and the developing bias, and the electrostatic image on the surface of the rotating drum B is sequentially developed as a toner image. The toner on the developing sleeve 2 that has not been subjected to the development is returned to the developing chamber by the subsequent rotation of the developing sleeve 2 and is conveyed.

The toner image on the surface of the rotating drum B is transferred onto a recording material by a transfer means (not shown), and the recording material is discharged as an image formed matter via a fixing means (not shown). After the transfer of the toner image to the recording material, the surface of the drum B is cleaned by the cleaning unit and is repeatedly used for image formation.

As in the developing device A, the elastic blade member 3 as a developer regulating member is brought into direct contact with the developing sleeve 2 as a developer carrier to regulate the layer thickness of the toner as a developer. Therefore, it is possible to form a very thin toner layer 5a on the developing sleeve 2 at the same time as applying a sufficient charge to the toner to develop an electrostatic image, and it is expected that the life of the toner layer is prolonged.

[0014]

By the way, in the developing device A as described above, the blade member 3 as the developer regulating member is elastically brought into contact with the developing sleeve 2 as the developer carrier. A certain amount of space S is required between the blade member 3 and the developing chamber frame 1 above the blade member (the side of the blade member that does not contact the developing sleeve). Therefore, the following problem may occur.

That is, since the elastic blade member 3 is in contact with the developing sleeve 2 via the toner layer, the developing sleeve 2
The upper toner layer includes the elastic blade member 3 and the developing sleeve 2.
Of the contact portion 4. In particular, the toner that has deteriorated during use for a long time and has reduced fluidity enters the space S between the blade member 3 and the portion of the developing chamber frame 1 above the blade member, and the entered toner is subjected to vibration or the like. When the elastic blade member 3 is compressed and aggregated, the elastic blade member 3 is pressed. Therefore, the contact pressure at the contact portion 4 between the elastic blade member 3 and the developing sleeve 2 is locally increased, or the elastic blade member 3 is distorted. Uneven toner coating occurs on the sleeve 2 and appears as image unevenness.

Further, even when toner coating unevenness does not occur, the elastic blade member 3 is pressed against the developing sleeve 2 more than necessary, so that scraping of the elastic blade member 3 and deterioration of toner are promoted.

Further, the toner that has entered the space S between the blade member 3 and the portion of the developing chamber frame 1 above the blade member is aggregated there and is not used for development. The space S between the blade member 3 and the portion of the developing chamber frame 1 above the blade member is a useless space.

Accordingly, an object of the present invention is to provide a developing device of this type with a developer regulating member (elastic blade member) 3 and a surface of the developer regulating member which is not in contact with the developer carrier (developing sleeve) 2. By preventing the developer (toner) 6 from entering the space (space) between the developing chamber frame 1 and the developer control member 3 and the developer carrier 2, the contact state is kept constant. The purpose is to constantly and satisfactorily form a thin layer of the developer on the developer carrier 2 so as to execute development without unevenness, and to extend the life of the developer regulating member and the developer.

[0019]

SUMMARY OF THE INVENTION The present invention is a developing device having the following configuration.

(1) A developer carrier rotatably supported and a developer regulating member that elastically contacts the developer carrier and regulates the amount of the developer applied on the developer carrier are provided. ,
In a developing device in which the tip of the developer regulating member extends in the direction of the developer chamber, the developer carrying member of the developer regulating member is disposed between the developer regulating member and the developer chamber frame inside the developer chamber. A developing device provided with a developer intrusion preventing member for preventing the developer from intruding into a surface that is not in contact with the developing device.

(2) The developing device according to (1), wherein the developer intrusion preventing member is fixed to at least one of the side of the developing magnification regulating member and the side of the developer chamber frame. apparatus.

(3) The developing device according to (1) or (2), wherein the developer intrusion preventing member is integrated with one of the developing magnification regulating member side and the developer chamber frame side. Developing device.

(4) Any one of the above (1) to (3)
3. The developing device according to claim 1, wherein the developer intrusion preventing member is an elastic body.

(5) In the developing device described in (4), the developer intrusion regulating member is located at a contact portion between the developer regulating member and the developer carrier, and the developer regulating member and the developer chamber frame. A developing device having a configuration of being sandwiched by a body and regulating the contact pressure between the developer regulating member and the developer carrying member by its own hardness.

(6) Any one of the above (1) to (4)
4. The developing device according to claim 1, wherein the developer intrusion preventing member is configured to press the developer regulating member against the developer carrier.

According to the above configuration, since the developer does not enter between the developer regulating member and the developer chamber frame, the contact state between the developer carrying member and the developer regulating member is always kept constant, and the developer can be used for a long time. Also, a stable developer coat can be obtained. Further, the deterioration of the developer regulating member and the developer can be prevented, and the life of the apparatus can be extended.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 (FIG. 1) In this embodiment, as shown in FIG. 1, a longitudinal direction of a developing chamber frame 1 portion above an elastic blade member 32 serving as a developer regulating member. An elastic sheet member (polyethylene terephthalate, trade name Mylar) is fixed as a developer intrusion preventing member 7 over the entire area, and is hung down toward the tip 3b of the elastic blade member 3 to close the space S. .

The other construction of the developing device is the same as that of the developing device A shown in FIG.

The presence of the elastic sheet member 7 as a developer intrusion preventing member causes the space S between the blade member 3 and the developing chamber frame 1 above the blade member to enter the space S. Intrusion of toner is prevented. Elastic sheet member 7
Is pressed by the toner 6 in the developing chamber and does not enter the space S (behind the blade member 3), the length of the elastic sheet member 7 is determined by the length of the elastic sheet member 7 and the tip 3b of the blade member 3. When touched, the elastic sheet member 7 was set to be longer, and the setting was made so as not to affect the toner supply to the developing sleeve 2 in the developing chamber.

Actually, when the long-term durability was performed with the developing device A in which the elastic sheet member 7 was extended by 2 to 3 mm from the position where the elastic sheet member 7 was in contact with the tip 3b of the blade member 3, the blade member 3 and the developing chamber frame There is no intrusion of toner into the space S between the body 1 and the blade member 3, resulting in distortion of the blade member 3.
No toner coat unevenness on the developing sleeve 2 occurred. The amount of scraping of the blade member 3 was 1/3 of the conventional one. When the contact pressure between the blade member and the developing sleeve 2 was measured, no change was observed in the contact pressure before and after the endurance.

<Embodiment 2> (FIG. 2) In this embodiment, as shown in FIG. 2, an unsupported tip 3 of an elastic blade member 3 as a developer regulating member is used.
The b side was extended and bent upward, and the extended bent portion 8 was used as a developer intrusion prevention member. Therefore, the elastic blade member 3 is one in which the developer intrusion member 8 is integrated.

In the present embodiment, the other construction of the developing device is the same as that of the developing device A shown in FIG.

The length of the bent portion of the elastic blade member 3, that is, the length of the developer intrusion preventing member 8, is determined by the space between the blade member 3 and the developing chamber frame 1 when the blade member 3 is in contact with the developing sleeve 2. The length was set sufficiently longer than the most open portion d of the portion S to prevent the toner from entering the space S.

With this configuration, long-term durability was confirmed, and the same effects as in Example 1 were obtained. Further, by forming the tip of the blade member 3 to be bent, the strength itself of the blade member 3 was increased, and a stable toner coat was obtained.

<Embodiment 3> (FIG. 3) In this embodiment, as shown in FIG.
Are fixed to an elastic blade member 3 as a developer regulating member, and the position thereof is just the contact portion 4 between the developing sleeve 2 and the blade member 3. When the developing sleeve 2 and the blade member 3 are in contact with each other, the developer intrusion prevention member 9 is sandwiched between the blade member 3 and the developing chamber frame 1 and is compressed by 25% from the actual dimension h. It has become. FIGS. 3B and 3C are enlarged views of the vicinity of the blade member before and during contact.

In the case of the present embodiment, the other configuration of the developing device is the same as that of the developing device A of FIG.

In this embodiment, the developer intrusion prevention member 9 is made of an elastic foam (urethane foam resin, trade name: maltoprene), and its hardness is 100 to 500 g at a 25% compression load ratio.
/ Cm ^2, and the contact pressure (linear pressure) between the developing sleeve 2 and the blade member 3 was regulated to 10 to 20 g / cm.

The same effects as those of the first and second embodiments were obtained by long-term use of this configuration.

Further, according to this configuration, the contact pressure between the blade member 3 and the developing sleeve 2 is reduced as in the prior art.
The load on the blade member 3 is reduced because the compression repulsion force of the moltoprene 9 as a developer intrusion preventing member is used instead of the elasticity of the developing sleeve itself. The effect of not affecting the toner coat on No. 2 was also obtained.

Further, since the thickness of the blade member 3 can be reduced, and the pressure can be applied by the foamed elastic body, the area of the nip in the contact portion 4 increases, and the ability to apply a tribo to the toner is increased, so that stable developing performance is obtained. Was also obtained over a long period of time.

In the present embodiment, moltoprene is used as the developer intrusion preventing member 9, but the same effect can be obtained by using other elastic materials.

[0042]

As described above, according to the present invention, the developer carrier rotatably supported and the developer applied to the developer carrier are brought into elastic contact with the developer carrier. A developer regulating member for regulating an amount of the developer regulating member, and a front end of the developer regulating member extending in the direction of the developer chamber, the surface of the developer regulating member and a surface of the developer regulating member not in contact with the developer carrier; By preventing the developer from entering between the side and the developing chamber frame portion and maintaining the contact state between the developer regulating member and the developer carrier constant, the developer can be thinned relative to the developer carrier. It was possible to stably and satisfactorily perform layer formation and to execute development without unevenness. Further, the life of the developer regulating member and the developer can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a developing device according to a first embodiment.

FIG. 2A is a schematic cross-sectional view of a developing device according to a second embodiment;
(B) is a partially enlarged view

FIG. 3A is a schematic cross-sectional view of a developing device according to a third embodiment;
(B) and (c) are enlarged views of the vicinity of the blade member before and during contact, respectively.

FIG. 4 is a schematic cross-sectional view of a conventional developing device.

[Explanation of symbols]

 A Overall Code of Developing Apparatus 1 Developing Room Frame 2 Developing Sleeve (Developer Carrier) 3 Elastic Blade Member (Developer Restricting Member) 4 Contact Section 5 Developer Stirring Member 6 Toner (Developer) 7.8.9 Developer entry member S Space B Rotary drum type image carrier

Claims (6)

[Claims] A developer carrier rotatably supported;
A developer regulating member that elastically contacts the developer carrying member and regulates an amount of the developer applied on the developer carrying member; a tip of the developer regulating member extends in a direction of the developer chamber; In the apparatus, between the developer regulating member and the developer chamber frame in the developer chamber, a developer intrusion preventing device that prevents the developer from entering the side of the developer regulating member that is not in contact with the developer carrier. A developing device comprising a member. 2. The developing device according to claim 1, wherein the developer intrusion prevention member is fixed to at least one of the side of the developing magnification regulating member and the side of the developer chamber frame. 3. The developing device according to claim 1, wherein the developer intrusion prevention member is integrated with one of the side of the developing magnification regulating member and the side of the developer chamber frame. 4. The developing device according to claim 1, wherein the developer intrusion prevention member is an elastic body. 5. The developing device according to claim 4, wherein the developer intrusion restricting member is located at a contact portion between the developer restricting member and the developer carrying member, and is provided between the developer restricting member and the developer chamber frame. A developing device, wherein the developing device has a configuration in which the abutment pressure between the developer regulating member and the developer carrying member is regulated by its own hardness. 6. The developing device according to claim 1, wherein the developer intrusion preventing member is configured to press the developer regulating member against the developer carrying member. apparatus.