JPH10213962A - Electrostatic latent image developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give fluidity to developer existing in space formed by a nip part between a supply roller and a developing roller and the wall of a developing housing opposed to the nip part and to prevent the developer from retaining by applying bias voltage on an electrode member disposed on a wall surface opposed to the nip part. SOLUTION: The electrode member 60 is disposed on the upper surface of the bottom wall 511 of the developing housing opposed to the nip part between the supply roller and the developing roller 53. In the member 60, a conductive layer 62 is formed on the surface of a sheet member 61 by vapor depositing conductive material such as aluminum. Bias voltage higher than applied voltage on the supply roller is applied on the conductive layer 62 of the member 60 from a power source 430 through a harness, a terminal 63, a machine screw 565 and a regulating blade 561. Therefore, electric field is generated from the conductive layer 62 of the member 60 toward the supply roller. As a result, the developer which is going to retain in the space formed by the member 60, the supply roller and the developing roller 53 has the fluidity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic latent image developing apparatus for developing an electrostatic latent image formed on an image carrier into a toner image in an image forming machine such as an electrostatic copying machine or a laser printer. .

[0002]

2. Description of the Related Art An electrostatic latent image developing apparatus in which an electrostatic latent image is developed into a toner image by a developer comprising a one-component toner in an image forming machine is widely used. An electrostatic latent image developing device of this type includes a developing housing having a developing chamber and a stirring chamber, and a developer that is disposed in the developing chamber and holds the developer on a peripheral surface in a developer holding area, and develops the held developer. A developing roller for transporting the electrostatic latent image to the developing area, and a supply roller disposed in contact with the peripheral surface of the developing roller in the developer holding area and supplying the developer to the peripheral surface of the developing roller. ,
A stirring means disposed in the stirring chamber for stirring the developer supplied through the developer supply opening and for sending the stirred developer to the development chamber; and a stirring means positioned between the developer holding area and the development area. A developer regulating unit that acts on the peripheral surface of the developing roller in the developer regulating region and regulates the amount of developer retained on the peripheral surface.

[0003]

In the electrostatic latent image developing apparatus constructed as described above, a nip portion between the supply roller and the developing roller and a wall of the developing housing facing the nip portion are provided. The developer tends to stay in the space formed by the above. If the developer stays in this way and a developer conveyance failure occurs, the developer leaks from the developing housing, the developer is blocked, and the replenishing roller formed of the foam is clogged. Further, when the developer stays, the developer deteriorates. When the deteriorated developer adheres to the peripheral surface of the developing roller and is conveyed to the developing area to perform the developing action, it causes an image defect.

The present invention has been made in view of the above-mentioned circumstances, and a main technical problem is that a space formed by a nip portion between a supply roller and a developing roller and a wall of a developing housing facing the nip portion. An object of the present invention is to provide an electrostatic latent image developing device which can impart fluidity to a developer existing in the developer and prevent the developer from staying.

[0005]

According to the present invention, in order to attain the above-mentioned main technical objects, a developer is provided on a peripheral surface in a developer holding area provided in the developer housing. A developing roller for transporting the held developer to a developing area and applying it to an electrostatic latent image; and a developing roller disposed in contact with a peripheral surface of the developing roller in the developer holding area to transfer the developer around the developing roller. A supply roller that supplies the developer to the surface, and a developer regulating unit that regulates the amount of developer retained on the peripheral surface of the developing roller in a developer regulating region located between the developer retaining region and the developing region. An electrostatic latent image developing apparatus, wherein an electrode member is disposed on a wall surface of the developing housing facing a nip portion between the replenishing roller and the developing roller, and a bias voltage is applied to the electrode member. Electrostatic latent The developing device is provided.

Further, according to the present invention, there is provided an electrostatic latent image developing device wherein a bias voltage applied to the electrode member is set to a value higher than a bias voltage applied to the supply roller.

Further, according to the present invention, there is provided an electrostatic latent image developing device in which the electrode member is disposed on a wall surface of the developing housing facing the nip portion on the side of the developer regulating region. .

According to the present invention, the developer regulating means includes a regulating blade formed of a conductive material having a mounting portion and a regulating portion attached to the developing housing, and a developing roller mounted on the regulating portion. There is provided an electrostatic latent image developing device including a regulating member made of an insulating material acting on a peripheral surface, wherein the regulating blade and the electrode member are electrically connected.

Further, according to the present invention, there is provided an electrostatic latent image developing device, wherein the electrode member is disposed on a wall surface of the developing housing opposite to the developer regulating area facing the nip portion. Provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an electrostatic latent image developing device constituted according to the present invention will be described in detail with reference to the accompanying drawings. In the illustrated embodiment, an example is shown in which the electrostatic latent image developing device configured according to the present invention is applied to a printer as an image forming machine.

FIG. 1 schematically shows an embodiment of a printer constructed according to the present invention. Printer 2
Is a small and low-speed laser printer used as a printing device such as a word processor in this embodiment, and includes a body housing 20 made of synthetic resin.
Is provided. The body housing 20 includes a box-shaped housing main body 21 whose upper part is open, and a cover 23 pivotally mounted on a shaft 22 provided on the upper part of the housing main body 21. The process unit 4 is detachably mounted at a substantially central portion of the body housing 20 configured as described above.

As shown in FIG. 2, the process unit 4 includes a photosensitive unit 40 and an electrostatic latent image developing device which is supported by the photosensitive unit 40 via a support shaft 5 so as to be swingable. Developing unit 50. The photoreceptor unit 40 includes a photoreceptor support means 41, and the photoreceptor support means 41 is provided with a pair of side wall members 411 spaced apart in the front-rear direction (only the rear side wall member is shown in FIG. 2). Shown) and the pair of side wall members 4
11 connecting members 412a, 412b connecting the lower portions
It has. The connecting members 412a and 412b are
The inner surfaces facing each other are arranged in parallel to form a charging means mounting space 412c in which a charging means described later is arranged between the two. The charging means mounting space 412c is located to face a charging area described later. The photoconductor supporting means 41 thus configured is integrally formed of a synthetic resin. At the upper end of the pair of side wall members 411 constituting the photoconductor supporting means 41 on the developing unit 50 side, mounting holes 4 are provided.
14 are provided. By inserting a support shaft 5 made of a metal bar disposed in a later-described developing housing of the developing unit 50 into a mounting hole 414 provided in the supporting portion 413, the photosensitive unit 40 and the developing unit 50 can be connected to each other. Is swingably supported.

The photosensitive unit 40 includes a photosensitive drum 42 having a photosensitive layer formed on a peripheral surface. The photosensitive drum 42 has a rotating shaft 421. The rotating shaft 421 is rotatably supported by a pair of side wall members 411 constituting the photosensitive member supporting means 41. That is, it is driven to rotate so as to sequentially pass through the charging area 422, the electrostatic latent image forming area 423, the developing area 424, and the transfer area 425. Charge area 422
The charging means 43 is disposed in the charging means mounting space 412c, which is located at a position opposite to the lower peripheral surface of the photosensitive drum 42. The charging means 43 includes a charging corona discharger 431 serving as a charger disposed in parallel with the photoreceptor drum 42 along the axial direction, and a charger holding member made of synthetic resin for mounting and holding the charging corona discharger. Member 43
The charging device holding member 432 is fitted in the charging means mounting space 412c and is positioned at a predetermined position. The grid of the charging corona discharger 431 constituting the charging means 43 is 850 in the illustrated embodiment.
V power supply 430. In addition, the charging area 4
A foreign matter collecting brush 44 that is in contact with the peripheral surface of the photoconductor drum 42 is provided between the photoconductor drum 42 and the transfer area 425 along the axial direction of the photoconductor drum 42. This paper dust collecting brush 44
Is made of acrylic fiber or the like, and has substantially the same length as the axial length of the photosensitive drum 42, is formed integrally with the charger holding member 432, and is disposed along the axial direction of the photosensitive drum 42. It is mounted on the brush support member 440. The upper end of the charger holding member 432 is formed between the charging corona discharger 431 disposed in the charging area 422 and the foreign matter collecting brush 44 so as to protrude so as to be close to the peripheral surface of the photosensitive drum 42. And forms a toner intrusion prevention wall 47. This toner intrusion prevention wall 47
When the residual toner adhered to the peripheral surface of the photosensitive drum 42 and removed by the foreign matter collecting brush 44 together with foreign matter such as paper dust falls without being reliably captured by the foreign matter collecting brush 44, the charging corona It has a function of preventing intrusion on the discharger 431. As a result, the toner whose movement is blocked by the toner intrusion prevention wall 47 is
The toner is deposited on the horizontal piece near the toner intrusion prevention wall 47 of the brush support member 440.

The transfer paper fed from diagonally upper left in FIG. 2 is directed to a transfer area 425 on the peripheral surface of the photosensitive drum 42 between a pair of side wall members 411 constituting the photosensitive member support means 41. A lower guide plate 451 that constitutes one of the pre-transfer guide plate pair 45 that guides the lower guide plate 451 is provided, and the lower guide plate 451 is integrally formed with the pair of side wall members 411. A plurality of guide ribs 451a are integrally formed on the upper surface of the lower guide plate 451 at intervals in the longitudinal direction (the direction perpendicular to the paper surface in FIG. 2). The lower guide plate 451 is also provided with a plurality of reinforcing ribs 45 on the lower surface at intervals in the longitudinal direction (the direction perpendicular to the paper surface in FIG. 2).
1 b is integrally formed, and the reinforcing rib 451 b is configured to abut on the support shaft 5. Therefore,
Even if the lower guide plate 451 is pressed by the upper surface thereof and bends, the reinforcing ribs 451b abut on the support shaft 5 to prevent the lower guide plate 451 from bending. Also, the lower guide plate 451
Is a pair of side wall members 41 constituting the photoreceptor support means 41.
1 serves as a connecting member for connecting the upper portions to each other, and the rigidity of the photosensitive member supporting means 41 can be improved. Further, in the illustrated embodiment, since the lower guide plate 451 is integrally formed with the pair of side wall members 411, the positional relationship with respect to the photosensitive drum 42 rotatably supported by the pair of side wall members 411 can be determined with high precision. Can be maintained. Note that the lower guide plate 4 in the illustrated embodiment is used.
Numeral 51 functions as a member for preventing the photosensitive drum 42 from contacting the photosensitive layer when the process unit 4 is attached and detached, and also functions as a member for preventing the developing unit 50 from touching a later-described developing roller. It also has a function of preventing toner scattered from the surface of the roller from adhering to the transfer paper or the transfer path of the transfer paper.

A post-transfer guide plate 46 for guiding the transfer paper transferred in the transfer area 425 to a fixing means described later is disposed between the pair of side wall members 411 constituting the photosensitive member supporting means 41. The post-transfer guide plate 46 is formed integrally with the pair of side wall members 411. Therefore, the post-transfer guide plate 46 functions as a connecting member for connecting the pair of side wall members 411 constituting the photoconductor supporting unit 41 to each other, and can improve the rigidity of the photoconductor supporting unit 41. The post-transfer guide plate 4 in the illustrated embodiment.
6 can also function as a contact preventing member for the photosensitive layer of the photosensitive drum 42 when the process unit 4 is attached or detached.

Next, the developing unit 50 as an electrostatic latent image developing device will be described. The developing unit 50 in the illustrated embodiment includes a developing housing 51 in which a developer composed of one-component toner is stored. The developing housing 51 has a bottom wall 511 and a front wall and a rear wall 512 (FIG. 2) formed to stand upright from front and rear ends (ends in a direction perpendicular to the paper surface in FIG. 2) of the bottom wall 511.
Only the rear side wall) and a left side wall 513, which are integrally formed of a synthetic resin and define a stirring chamber 514 and a developing chamber 515. A stirring chamber 51 is provided on a bottom wall 511 of the developing housing 51.
A partition wall 516 provided in the front-rear direction (the direction perpendicular to the paper surface in FIG. 2) between the developing chamber 4 and the developing chamber 515 is integrally formed. Both left and right surfaces of the partition wall 516 are formed on arcuate guide surfaces 516a and 516b. Between the front and rear side walls 512 constituting the developing housing 51, a connecting member 517 provided at the upper part on the side of the developing chamber 515 is provided, and is formed integrally with the front and rear side walls 512. A toner supply hole 518 is formed in the rear side wall 512 of the developing housing 51.
8 is fitted with a cap 519. At the upper end of the developing housing 51 on the side of the developing chamber 515, the support shaft 5 is provided so as to penetrate the front and rear side walls 512. The photosensitive unit 4 is provided at both ends of the support shaft 5.
A pair of side wall members 41 constituting the photosensitive member supporting means 41
By fitting the mounting holes 414 provided in the first support portion 413, the photoconductor unit 40 and the developing unit 50 are supported so as to be able to swing mutually. The photoconductor unit 4
0 and the developing housing 51
A coil spring 52 serving as a spring means is interposed between the front end and the rear end of the photosensitive member supporting means 41 and the developing housing 5.
Numerals 1 are urged to draw each other with the support shaft 5 as a fulcrum. The developing housing 51 is open above and to the right, that is, on the photoconductor unit 40 side.

In the developing housing 51, a developing roller 53, a supply roller 54, a stirring means 55 and a developer regulating means 56 are provided. The developing roller 53 is
A rotating shaft 531 provided in the developing chamber 515 of the developing housing 51 and rotatably mounted on the front and rear side walls 512 constituting the developing housing 51, and a solid synthetic rubber roller fixed to the outer peripheral surface of the rotating shaft 531 532. The rotating shaft 531 can be formed from an appropriate metal material such as stainless steel. Solid synthetic rubber roller 53
2 is made of a relatively flexible and conductive material, for example, a conductive solid synthetic rubber such as urethane rubber. In the illustrated embodiment, a solid synthetic rubber roller 5 is used.
The surface roughness of the peripheral surface of No. 32, that is, the ten-point average roughness Rz specified in JIS B 0601 is set to 5.0 to 12.0. The volume resistance of the solid synthetic rubber roller 532 is set to about 10 ⁴ to 10 ⁹ Ω · cm. The roller hardness of the solid synthetic rubber roller 532 is set to 60 to 80 in Asker C hardness in the illustrated embodiment. The roller 532 of the developing roller 53 configured as described above is exposed through a right opening formed in the developing housing 51, and is exposed to the photosensitive drum 42.
Is positioned opposite to. The peripheral surface of the roller 532 constituting the developing roller 53 is pressed against the peripheral surface of the photosensitive drum 42 in the developing region, and the peripheral surface of the roller 532 is slightly elastically compressed at the pressed nip. ing. Rotating shaft 53 of developing roller 53
1 is driven to rotate from the lower side to the upper side in a direction indicated by an arrow by a driving unit (not shown), that is, in a developing area which is a contact portion between the roller 532 and the photosensitive drum 42. The rotation of the rotation shaft 531 causes the roller 532 to rotate.
The roller 532 is also driven to rotate in the direction indicated by the arrow, and the peripheral surface of the roller 532 is sequentially moved through the developer holding area 533, the developer regulating area 534, and the developing area 424. In the illustrated embodiment, a bias voltage of 400 V is applied to the rotating shaft 531 of the developing roller 53.

The replenishing roller 54 is disposed in the developing chamber 515 of the developing housing 51 in parallel with the developing roller 53, and is rotatably mounted on the front and rear side walls 512 constituting the developing housing 51. A shaft 541;
And a roller 542 fixed to the outer peripheral surface of the rotating shaft 541. The rotating shaft 541 can be formed of an appropriate metal material such as stainless steel, similarly to the rotating shaft 531 of the developing roller 53. The roller 542 is made of foam such as foamed silicone or foamed urethane. The roller 542 is a roller 5 of the developing roller 53 in a developer holding region 533 which is a nip portion with the developing roller 53
32. Roller 54 of supply roller 54
The hardness of the foam constituting the developing roller 2 is considerably smaller than the hardness of the roller 532 constituting the developing roller 53 (for example, about 35 in Asker C hardness), and the roller 542 is pressed against the roller 532 of the developing roller 53. It is desirable that the roller 542 be elastically compressed by about 0.1 to 0.6 mm in the nip area. Roller 5
42 also has conductivity, and its volume resistance is 10 ² to 1
It is set to about 0 ⁶ Ω · cm. The rotating shaft 541 of the replenishing roller 54 is rotated from the upper side to the lower side in a direction indicated by an arrow by a driving unit (not shown), that is, in a developer holding area 533 which is a nip portion between the roller 542 and the roller 532 of the developing roller 53. I'm sullen. Rotary axis 5
Due to the above rotation of the roller 41, the roller 542 is also driven to rotate in the direction shown by the arrow. In the illustrated embodiment,
The rotation shaft 541 of the supply roller 54 has the developing roller 53
A bias voltage of 400 V which is higher than the applied voltage is applied.

The peripheral speed V1 of the photosensitive drum 42, the peripheral speed V2 of the developing roller 53, and the peripheral speed V3 of the replenishing roller 54 are set in a relationship of V1 <V2 <V3.
In the illustrated embodiment, the relationship between the peripheral speed V1 of the photosensitive drum 42 and the peripheral speed V2 of the developing roller 53 is as follows.
1.2V1 ≦ V2 ≦ 2.5V1, the peripheral speed V2 of the developing roller 53 and the peripheral speed V3 of the replenishment roller 54 are set.
Is set to be 1.0V2 ≦ V3 ≦ 2.0V2. When the peripheral speed V2 of the developing roller 53 becomes 1.2 V1 or less, the supply of the developer to the photosensitive drum 42 becomes insufficient, and the image density is reduced. When the peripheral speed V2 of the developing roller 53 becomes 1.2 V1 or less, the scraping action of the developing roller 53 against the non-transferred developer attached to the photosensitive drum 42 after the transfer is reduced. This causes a so-called offset fog to occur because the photoreceptor drum 42 cannot be removed. On the other hand, when the peripheral speed V2 of the developing roller 53 becomes 2.5 V1 or more, the driving torque of the developing roller 53 increases, and the developer is scattered by centrifugal force. Further, when the peripheral speed V3 of the supply roller 54 becomes 1.0 V2 or less, the supply of the developer to the developing roller 53 becomes insufficient, which causes a decrease in image density. Also, the peripheral speed V of the supply roller 54
When 3 is 1.0 V2 or less, the action of scraping the peripheral surface of the developing roller 53 by the replenishing roller 54 is weak. Therefore, if the non-transferred developer adhered to the photosensitive drum 42 adheres to the developing roller 53 after the transfer, It becomes difficult to remove the adhered developer, and the adhered developer causes a so-called ghost phenomenon that appears during the next development. On the other hand, when the peripheral speed V3 of the supply roller 54 becomes 2.0 V2 or more, the supply roller 54
, The developer tends to stay above the nip portion between the supply roller 54 and the developing roller 53, which causes a shortage of the developer supply to the developing roller 53.

In the stirring chamber 514 of the developing housing 51, a stirring means 55 is provided. The stirring means 55
A rotating shaft 551 rotatably mounted on the front and rear side walls 512 constituting the developing housing 51, a stirring member 552 fixed to the rotating shaft 551, and An elastic stirring sheet member 553 attached to the stirring member 552 is included.
The stirring member 552 is formed of a synthetic resin,
A plurality of openings are provided in a longitudinal direction (a direction perpendicular to the paper surface in FIG. 2). The stirring sheet member 553 is made of, for example, polyethylene terephthalate (PET) having flexibility and elasticity.
P) It is formed of resin, and is fixed to the edge of the tip of the stirring member 552 by an adhesive or the like. The stirring means 55 thus configured is continuously driven to rotate in a direction indicated by an arrow in FIG. 2 by a driving means (not shown).

Next, regarding the developer regulating means 56,
This will be described with reference to FIG. The developer regulating means 56 includes a regulating blade 561 made of a thin steel plate having flexibility and being pressed against the peripheral surface of the roller 532 constituting the developing roller 32. Regulator blade 561
Is made of, for example, a conductive plate material such as a stainless steel plate or a spring steel plate having a thickness of about 0.1 to 0.2 mm, and has a longitudinal dimension substantially the same as the length of the roller 532 constituting the developing roller 53. doing. Regulator blade 56
1 has a mounting part 561a and a regulating part 561b. A regulating portion 561b constituting the regulating blade 561
A regulating member 562 made of an insulating material such as urethane rubber is mounted on the surface (on the side facing the developing roller 32). The restricting member 562 has a semicircular shape with a radius of about 1 mm in the illustrated embodiment.
Has a length substantially the same as the length in the longitudinal direction, and a flat portion is attached to the surface of the regulating portion 561b with an adhesive. The mounting portion 561a of the regulating blade 561 is connected to the photoconductor unit 40 on the bottom wall 511 of the developing housing 51.
It is sandwiched and attached to the blade attachment portion 511a provided at the side open end by the holding plate 563. A contact plate 564 is provided between the mounting portion 561a of the regulating blade 561 and the blade mounting portion 511a of the developing housing 51. Blade mounting portion 511 of developing housing 51
a, the attachment plate 564 of the backing plate 564 and the regulating blade 561
The a and the holding plate 563 are provided with a plurality of screw insertion holes at predetermined positions at positions corresponding to each other in the longitudinal direction. A blade mounting portion 511 of the developing housing 51 is inserted into a plurality of screw insertion holes provided in each of the above members.
A plurality of metal screws 565 are inserted from the side a, and a female screw 56 formed in a screw insertion hole provided in a holding plate 563 with a screw portion 565 a formed at the tip of the screw 565.
3a, the mounting portion 561a of the regulating blade 561 is connected to the blade mounting portion 51 of the developing housing 51.
1a is clamped and fixed by a holding plate 563. The blade mounting portion 511a and the mounting portion 561a of the regulating blade 561 are provided above the backing plate 564.
A seal member 566 made of a sponge material or the like is provided in the space defined by the above.

In the illustrated embodiment, an electrode member 60 is disposed on the upper surface of the bottom wall 511 of the developing housing 51 facing the nip between the supply roller 54 and the developing roller 53. This electrode member 60 is formed by forming a conductive layer 62 by vapor deposition of a conductive material such as aluminum on the surface of a sheet member 61 having a thickness of 0.1 to 0.2 mm made of, for example, a polyethylene terephthalate (PETP) resin film. The length in the longitudinal direction is substantially the same as the length of the supply roller 54 and the developing roller 53. In addition,
The electrode member 60 may be made of a metal plate such as aluminum. One end of the electrode plate 60 is connected to the supply roller 5.
4 is located substantially below the axis of the developing housing 5.
It is stuck on the upper surface of the bottom wall 511 with an adhesive. The electrode member 60 mounted on the bottom wall 511 of the developing housing 51 is connected to the blade mounting portion 511 a and the metal plate 5.
64, and the other end is sandwiched between the backing plate 564 and the mounting portion 561a of the regulating blade 561. Therefore, the conductive layer 62 of the electrode member 60 is electrically connected to the regulating blade 561. The regulating blade 56
A terminal 63 is attached to the screw 565 for attaching the fixing member 1 to the blade attaching portion 511 a, and the terminal 63 is connected to a power supply 430 of a charging corona discharger 431 constituting the charging means 43 by a harness 65. For this reason, in the illustrated embodiment, the conductive layer 6 of the electrode member 60 is used.
2, a bias voltage of 850 V higher than the voltage (400 V) applied to the supply roller 54 is applied from the power supply 430 via the harness 65, the terminal 63, the screw 565, and the regulating blade 561. Accordingly, an electric field is generated from the conductive layer 62 of the electrode member 60 toward the replenishing roller 54, and as a result, the developer flows into the space formed by the electrode member 60 and the replenishing roller 54 and the developing roller 53. Nature occurs. The bias voltage applied to the electrode member 60 is desirably set to a value higher than the voltage applied to the replenishing roller 54. However, since an electric field may be generated in the space, the voltage applied to the replenishing roller 54 It does not need to be higher and may be an AC voltage.

The developing housing 51 is provided with a lid 57 that covers the open upper part. The lid 57 is made of a synthetic resin, and is fixed to an upper surface of the front and rear side walls 512, the left side wall 513, and the upper surface of the connecting member 517 constituting the developing housing 51 by an adhesive. A regulating portion 571 that extends in the front-rear direction (a direction perpendicular to the paper surface in FIG. 2) and protrudes toward the developing chamber 515 is integrally formed on the inner surface of the lid 57 at a position facing the supply roller 54. A predetermined interval is provided between the lower end of the regulating portion 571 and the outer peripheral surface of the roller 542 constituting the supply roller 54. In the illustrated embodiment, a sheet-shaped seal member 58 is attached to the connecting member 517 constituting the developing housing 51. The sheet-shaped sealing member 58 is made of, for example, polyethylene terephthalate (P
It is made of a sheet member having flexibility and elasticity, such as ETP) resin, and has substantially the same length as the axial length of the roller 532 constituting the developing roller 53. One end of the sheet-shaped sealing member 58 is connected to the connecting member 517.
Is fixed to the developing roller 53 by a fixing means such as an adhesive.
2 is elastically brought into contact with the peripheral surface. The sheet-shaped sealing member 58 thus configured is provided together with the blade 561 of the developer regulating means 56 on the developing housing 5.
The developer is prevented from scattering from the opening on the side of the photoconductor unit 40. In the illustrated embodiment, the supply roller 5
An electrode member 600 is provided on the lower surface of the lid 57 facing the nip portion between the developing roller 4 and the developing roller 53. This electrode member 6
Reference numeral 00 denotes a sheet member 6 made of a polyethylene terephthalate (PETP) resin film in the same manner as the electrode member 60.
The conductive layer 602 is formed by vapor deposition of a conductive material such as aluminum on the surface of the developing roller 01, and has a longitudinal dimension substantially equal to the length of the supply roller 54 and the developing roller 53. The electrode member 600 is also connected to the power supply 430 of the charging corona discharger 431 constituting the charging means 43. Therefore, a bias voltage of 850 V higher than the voltage (400 V) applied to the supply roller 54 is applied to the electrode member 600. Accordingly, an electric field is generated from the conductive layer 602 of the electrode member 600 toward the replenishing roller 54, and as a result, the developer flowing to the space formed by the electrode member 600, the replenishing roller 54 and the developing roller 53 flows. Nature occurs. The bias voltage applied to the electrode member 600 is desirably set to a value higher than the voltage applied to the supply roller 54. However, since an electric field may be generated in the space, the voltage applied to the supply roller 54 It does not need to be higher and may be an AC voltage.

The process unit 4 configured as described above is detachably mounted on the body housing 20 of the printer 2 as shown in FIG. That is, the upper part of the housing main body 21 constituting the body housing 20 is opened by turning the cover 23 constituting the body housing 20 of the printer 2 around the axis 22 counterclockwise in FIG. Next, the process unit 4 is mounted in the housing body 21 from above. The housing body 21
Inside, a positioning means (not shown) capable of mounting the photoconductor unit 40 of the process unit 4 at a predetermined position is provided. The process unit 4 is connected to the body housing 20.
When the cover 22 is attached to the housing body 21 of the
By turning clockwise in FIG. 1 around two directions, the upper part is closed.

As shown in FIG. 1, a lower part of a housing body 21 constituting a body housing 20 of the printer 2 includes:
A laser unit 24 is provided. The laser unit 24 irradiates the photosensitive layer of the photosensitive drum 42 with a laser beam corresponding to print data from, for example, a word processor connected to the printer 2 in the electrostatic latent image forming area 423 of the process unit 4, Form a latent image. A fixing roller pair 25 is disposed on the downstream side of the post-transfer guide plate 46 on the housing body 21 constituting the body housing 20 of the printer 2, and a discharge roller pair 26 is disposed on the downstream side of the fixing roller pair 25. Are arranged. Further, a discharge tray 27 is provided downstream of the discharge roller pair 26.

A paper feed tray 28 on which transfer paper is placed is disposed on a cover 23 constituting the body housing 20 of the printer 2 at an upper left portion in FIG. A paper feed roller 29 is provided downstream of the paper feed tray 28,
The paper feed roller 29 is driven to rotate in a direction indicated by an arrow in FIG. A friction pad 30 for separating sheets is provided opposite to the sheet feeding roller 29. Further, a non-contact type transfer roller 31 is provided in the transfer area 422 so as to face the photosensitive drum 42. The transfer roller 31 is formed of conductive urethane foam, and is rotatably supported by the cover 23. The transfer roller 31 is provided with collars (not shown) made of an insulating material such as a synthetic resin having an outer diameter larger than that of the transfer roller 31 at both ends thereof, and the collars are arranged in contact with the peripheral surface of the photosensitive drum 42. Has been
Accordingly, the transfer roller 31 is driven to slide while the photosensitive drum 42 rotates. The gap between the peripheral surface of the transfer roller 31 and the peripheral surface of the photosensitive drum 42 is 0.5 m.
m. A constant current of, for example, 10 μA is applied to the transfer roller 31 configured as described above.
An upper guide plate 452 constituting the other of the pre-transfer guide plate pair 45 is disposed on the cover 23.

The printer equipped with the electrostatic latent image developing device in the illustrated embodiment is configured as described above, and its operation will be described below. Each of the above members starts operating based on a print command from a word processor (not shown) or the like, and is charged by a corona discharger 43 for the photosensitive drum.
Is charged to a specific polarity substantially uniformly. Next, a laser beam corresponding to print data from a word processor or the like is emitted from the laser unit 24 to the charged surface of the photosensitive layer of the photosensitive drum 42, and an electrostatic latent image is formed. The electrostatic latent image thus formed on the photosensitive layer of the photosensitive drum 42 is developed into a toner image by the developing operation of the developing unit 50. The developing unit 5
The developing action of 0 will be described later in detail. On the other hand,
The transfer paper placed on the paper feed tray 28 is fed to a paper feed roller 29.
And the friction pads 30 are fed one by one.
Then, the transfer paper is guided by the pre-transfer guide plate pair 45 and is conveyed between the photosensitive drum 42 and the transfer roller 31, and the toner image formed on the photosensitive drum 42 is transferred to the surface thereof. The transfer paper on which the toner image has been transferred is transferred to the post-transfer guide plate 46.
And is conveyed to the fixing roller pair 25. The transfer paper on which the toner image has been heated and fixed by the fixing roller pair 25 is discharged onto a discharge tray 27 by the discharge roller pair 26. On the other hand, when the peripheral surface of the photosensitive drum 42 that has passed through the transfer area 425 passes through the foreign matter collecting brush 44, foreign matter such as paper dust adhered to the peripheral surface is removed by the foreign matter collecting brush 44. At this time, residual toner adhering to the peripheral surface of the photosensitive drum 42 is removed together with foreign matter such as paper dust. The removed residual toner may fall without being reliably captured by the foreign matter collecting brush 44. If the dropped toner accumulates on the charging corona discharger 431, it causes charging unevenness. In the illustrated embodiment, the toner intrusion prevention wall 47 causes the dropped toner to move toward the charging corona discharger 431. Intrusion is prevented.

Next, the developing operation of the developing unit 50 will be described. By starting the operation of the developing unit 50,
The developing roller 53, the supply roller 54, and the stirring means 5
5 are rotationally driven in directions indicated by arrows by drive means (not shown). Stirring member 55 constituting stirring means 55
2 and the stirring sheet member 553 rotate in the direction indicated by the arrow, the developer accommodated in the stirring chamber 514 passes over the partition wall 516 while being stirred, and
Is supplied into the developing chamber 514 from above. At this time, the regulating portion 571 formed on the inner surface of the lid 57 causes
The amount of the developer supplied into the developing chamber 514 is limited so as not to be excessive. The developer supplied by the agitating unit 55 in this manner rides on the roller 542 of the supply roller 54 and is transported to the nip portion which is the developer holding area 533 with the roller 532 of the developing roller 53. Since the supply roller 54 and the developing roller 53 rotate in the same direction from the upper side to the lower side in the developer holding area 533 which is a nip portion as described above, the supply roller 54 and the developing roller 53
The developer is sufficiently supplied to the developer, and the shortage of the developer can be prevented. The replenishing roller 54 and the developing roller 5
3 is a developer holding area 533 which is a nip portion as described above.
, The motor can be driven reliably without requiring a large driving force.

As described above, the developer conveyed to the developer holding area 533, which is a nip portion between the supply roller 54 and the developing roller 53, is supplied to the roller 53 constituting the developing roller 53.
2 and is conveyed toward the developer regulating area 534. At this time, the supply roller 54 and the developing roller 53
Are rotated in the same direction from the upper side to the lower side in the developer holding area 533 which is the nip portion as described above, so that the developer is held by the developing roller 53 through both nip portions, and the developer is regulated. Since they are conveyed to the 534 and the developing zone 535, they are rubbed against each other when passing through the nip portion and are sufficiently charged, so that the occurrence of so-called fog is prevented.

In the developer regulating area 534, a regulating member 562 mounted on the surface of the blade 561 constituting the developer regulating means 56 acts on the developer held on the peripheral surface of the roller 532 of the developing roller 53. And the roller 532
The developer held on the peripheral surface is regulated to a required amount to form a thin layer. In the developer regulation area 534, the bottom wall 51 of the development housing 51 is regulated by the regulation member 562 attached to the blade 561 of the developer regulation means 56.
The developer scraped off on top of the partition wall 51 is rotated by the supply roller 54 in the direction indicated by the arrow.
6 along the guide surface 516b.

As described above, the regulating member held on the peripheral surface of the roller 532 constituting the developing roller 53 in the developer retaining area 533 and the regulating member mounted on the regulating blade 561 of the developer regulating means 56 in the developer regulating area 534. 562
The developer formed in a thin layer by the action of is transported to the developing area 424 with rotation in the direction of the arrow. In the developing area 424, a developer is applied to the electrostatic latent image on the electrostatic photosensitive member disposed on the peripheral surface of the photosensitive drum 42,
The electrostatic latent image is developed into a toner image. For example, the electrostatic latent image has a non-image area charged to about +600 V and + 12V.
It has an image area charged to about 0 V, and toner as a developer is attached to the image area (so-called reversal development). The photosensitive drum 42 and the developing roller 53 are driven to rotate in a direction indicated by an arrow in FIG.
In the developing area 535, the peripheral surface of the photosensitive drum 42 and the peripheral surface of the roller 532 constituting the developing roller 53 are both moved upward from below in the same direction. Roller 532
And the peripheral speed V1 of the photosensitive drum 42 are as follows.
Since 2V1 ≦ V2 ≦ 2.5V1, a sufficient amount of developer is conveyed to the developing area 535 by the roller 532 of the developing roller 53, and the peripheral surface of the roller 532 slides on the peripheral surface of the photosensitive drum 42. The developer that has once adhered to the non-image portion of the electrostatic latent image is appropriately peeled off by the rubbing action, so that a good toner image having an appropriate development density and no fog can be obtained. On the other hand, the used developer held on the peripheral surface of the roller 532 constituting the developing roller 53 and passing through the developing area 424 is transferred to the surface of the replenishing roller 54 at the nip portion between the developing roller 53 and the replenishing roller 54. It is. Since the peripheral speed of the supply roller 54 is set to be higher than the peripheral speed of the developing roller 53, the developer is moved in the nip portion. The adhesive force of the transfer developer can be weakened and collected, so that a so-called ghost caused by the non-transfer developer adhered to the developing roller 53 can be prevented.

The developing action is performed as described above, and the developer regulated by the developer regulating means 56 in the developer regulating area 534 and scraped off on the bottom wall 511 of the developing housing 51 is moved by the arrow of the supply roller 54. It is desirable that the toner is conveyed toward the partition wall 516 by rotation in the direction shown by the arrow, but the nip between the supply roller 54 and the developing roller 53 and the bottom wall 5 of the developing housing 51 facing the nip.
It is difficult to impart fluidity to all the developers existing in the space formed by the step 11. Therefore, the developer existing in the space tends to stay, and blocking of the developer occurs. However, in the illustrated embodiment, the electrode member 60 is disposed on the upper surface of the bottom wall 511 of the developing housing 51 facing the nip portion between the replenishing roller 54 and the developing roller 53. The power supply 430 is provided to the layer 62 and the regulating blade 561.
850 V higher than the applied voltage (400 V) to the replenishment roller 54 is applied via the harness 65, the terminal 63, and the screw 565 to the replenishment roller from the conductive layer 62 of the electrode member 60 and the regulating blade 561. An electric field is generated toward. As a result, the developer that tends to stay in the space flows due to the electric field and flows toward the supply roller 54.
The developer flowing toward the supply roller 54 in this manner is conveyed toward the partition wall 516 by the rotation of the supply roller 54 in the direction indicated by the arrow. In the illustrated embodiment, the bias voltage applied to the electrode member 60 is set to a value higher than the voltage applied to the replenishing roller 54. However, since an electric field may be generated in the space, the replenishing roller 54 may be used. It is not necessary to be higher than the voltage applied to the AC voltage, and the AC voltage may be used.

In the illustrated embodiment, an electrode member 600 is also provided on the lower surface of the lid 57 facing the nip between the supply roller 54 and the developing roller 53. Since a bias voltage of 850 V higher than the applied voltage (400 V) to the supply roller 54 is applied, an electric field is generated from the electrode member 600 toward the supply roller 54. As a result, the developer existing in the space formed by the nip portion between the replenishing roller 54 and the developing roller 53 and the lid 57 opposed to the nip portion generates fluidity due to the electric field, and does not stagnate. Fluidized. In the illustrated embodiment, the bias voltage applied to the electrode member 600 is set to a value higher than the voltage applied to the replenishing roller 54. However, since an electric field may be generated in the space, the replenishing roller 54 may be used. It is not necessary to be higher than the voltage applied to the AC voltage, and the AC voltage may be used.

Although the present invention has been described based on the embodiment in which the present invention is applied to a printer, the present invention is not limited to the illustrated embodiment. For example, the present invention can be applied to an electrostatic copying machine. Various changes or modifications can be made without departing from the scope of the technical idea of the present invention.

[0035]

The electrostatic latent image developing device according to the present invention is constructed as described above, and has the following operational effects.

That is, according to the present invention, the electrode member is disposed on the wall surface of the developing housing opposite to the nip between the supply roller and the developing roller, and a bias voltage is applied to the electrode member. An electric field is generated toward the supply roller. As a result, an electric field is generated in a space formed by the electrode member, the supply roller, and the developing roller. As a result, the developer existing in the space has fluidity due to the electric field, and is always allowed to flow without stagnation.

Further, since the bias voltage applied to the electrode member is set to a value higher than the bias voltage applied to the replenishing roller, the flow of the developer toward the replenishing roller is promoted by the potential difference. The rollers are more effectively conveyed.

Further, according to the present invention, since the electrode member is disposed on the wall surface of the developing housing facing the nip portion on the side of the developer regulating region, the developing member present on the developer regulating region side is provided. It is possible to reliably prevent the stagnation of the developer, and it is possible to prevent the occurrence of an image defect due to a so-called fogging phenomenon caused by the stagnation of the developer in the developer regulation area.

Further, according to the present invention, the developer regulating means for regulating the amount of developer held on the peripheral surface of the developing roller in the developer regulating area has a mounting portion attached to the developing housing and a regulating portion. A regulating blade formed of a conductive material, and a regulating member made of an insulating material attached to the regulating portion and acting on the peripheral surface of the developing roller, wherein the regulating blade and the electrode member are electrically connected. Since the connection is made, a bias voltage having the same potential as that of the electrode member is also applied to the regulating blade, so that an electric field can be effectively applied by the developer existing on the developer regulating region side.

Further, according to the present invention, since the electrode member is disposed on the wall surface of the developing housing opposite to the developer regulating region facing the nip portion,
Since the developer existing on the side opposite to the developer regulation area side is not caused to flow and stay, the supply of the developer from the supply roller to the developing roller is reliably performed.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing an embodiment of an image forming apparatus equipped with an electrostatic latent image developing device configured according to the present invention.

FIG. 2 is a cross-sectional view of an image forming machine equipped with the electrostatic latent image developing device configured according to the present invention shown in FIG.

FIG. 3 is a perspective view of a main part of a developer regulating unit and an electrode plate constituting the electrostatic latent image developing device shown in FIG. 2;

[Explanation of symbols]

 2: printer 4: process unit 5: support shaft 20: body housing 21: housing body 23: cover 24: laser unit 25: fixing roller pair 26: discharge roller pair 27: discharge tray 28: paper feed tray 29: paper feed Roller 30: Friction pad 31: Transfer roller 40: Photoconductor unit 41: Photoconductor support means 42: Photoconductor drum 43: Charging means 44: Foreign matter collecting brush 45: Guide plate pair before transfer 46: Guide plate after transfer 47: Toner Intrusion prevention wall 50: developing unit 51: developing housing 52: coil spring 53: developing roller 54: supply roller 55: stirring means 56: developer regulating means 57: lid 58: sheet-shaped seal member 60: electrode member 431: charging Corona discharger 411: Side wall member of photoconductor support unit 412: Connecting member of photoconductor support unit 42 : Charging area 423: electrostatic latent image forming area 424: developing area 425: transfer area 470: toner intrusion prevention wall 514: stirring chamber 515: developing chamber 517: connecting member of developing housing 533: developer holding area 534: developer Control area 561: Control blade 561a: Mounting section of control blade 561b: Control section of control blade 562: Control member 600: Electrode member

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuki Miyaji 1-2-28 Tamatsukuri, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. Mita Kogyo Co., Ltd.

Claims (5)

[Claims] 1. A developing housing, and a developer holding area provided in the developing housing, for holding the developer on a peripheral surface in a developer holding area, transferring the held developer to the developing area, and applying the held developer to an electrostatic latent image. A developing roller, a replenishing roller disposed in contact with the peripheral surface of the developing roller in the developer retaining area and supplying the developer to the peripheral surface of the developing roller; and a supply roller between the developer retaining area and the developing area. And a developer regulating means for regulating an amount of developer held on a peripheral surface of the developing roller in a developer regulating area located at a position between the supply roller and the developing roller in the developing housing. An electrostatic latent image developing device, wherein an electrode member is provided on a wall surface facing a nip portion with a roller, and a bias voltage is applied to the electrode member. 2. The electrostatic latent image developing device according to claim 1, wherein a bias voltage applied to said electrode member is set to a value higher than a bias voltage applied to said supply roller. 3. The electrostatic latent image developing device according to claim 1, wherein said electrode member is provided on a wall surface of said developing housing on a side of said developer regulating region facing said nip portion. 4. The developer regulating means includes: a regulating blade formed of a conductive material having a mounting portion and a regulating portion attached to the developing housing; and a developer blade attached to the regulating portion and acting on a peripheral surface of the developing roller. The electrostatic latent image developing device according to claim 3, further comprising a regulating member made of an insulating material, wherein the regulating blade and the electrode member are electrically connected. 5. The electrostatic latent image developing device according to claim 1, wherein the electrode member is provided on a wall surface of the developing housing opposite to the developer regulating region facing the nip portion.