JP3465177B2 - Image forming machine and process unit applied to it - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention develops an electrostatic latent image formed on a photosensitive layer of a photosensitive drum such as an electrostatic copying machine or a laser printer into a toner image and transfers the toner image onto a transfer paper. The present invention relates to an image forming machine and a process unit applied to it.

[0002]

2. Description of the Related Art An image forming machine of this kind is arranged rotatably and a photosensitive drum which sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and is arranged in the charging area. A charger that charges the peripheral surface of the photosensitive drum to a specific polarity, and a developing device that is disposed in the developing area and develops the electrostatic latent image formed on the peripheral surface of the photosensitive drum into a toner image in the electrostatic latent image forming area. The image forming apparatus includes an apparatus and a transfer unit that is arranged in the transfer area and transfers the toner image formed on the peripheral surface of the photosensitive drum to a transfer paper. In the image forming machine of such a type, the position of each area changes depending on whether the transfer paper is passed through the upper side or the lower side of the photosensitive drum. Generally, a structure in which the transfer paper passes under the photosensitive drum is often used. In this case, the transfer area is located under the photosensitive drum, so the charging area is above the photosensitive drum. Will be located. Also,
In the type in which the transfer paper is passed over the photosensitive drum, the transfer area is located above the photosensitive drum, and therefore the charging area is located below the photosensitive drum.

[0003]

Therefore, in the image forming machine in which the toner remaining on the peripheral surface of the photoconductor drum that has passed through the transfer area is collected by the developing device, the photoconductor is If the foreign matter such as paper powder attached to the peripheral surface of the drum is collected by the developing device together with the toner, the subsequent image quality will be deteriorated. Therefore, it has been proposed to dispose a foreign matter collecting brush between the charging area and the transfer area to remove foreign matter such as paper dust attached to the peripheral surface of the photosensitive drum. However, it is desirable that the foreign matter collecting brush removes only foreign matter such as paper dust and allows the residual toner adhering to the peripheral surface of the photosensitive drum to pass therethrough, but the residual toner may be scraped off. There is no problem if the scraped residual toner is reliably captured by the foreign matter collecting brush, but most of the toner is dropped because the particles are smaller than the foreign matter such as paper dust. Therefore, in the image forming machine configured such that the charging area is located below the photosensitive drum, the toner scraped off by the foreign matter collecting brush is deposited on the upper surface of the charger provided in the charging area. When the toner is deposited on the upper surface of the charger, uneven charging occurs, which causes a defective image.

The present invention has been made in view of the above facts, and its main technical problem is to provide a charging area and a transfer area in a structure in which the charging area is located below the photosensitive drum. Even if the residual toner removed together with the foreign matter falls from the peripheral surface of the photoconductor drum by the foreign matter collecting brush disposed between and, it is possible to prevent the residual toner from being deposited on the charger arranged in the charging area. An image forming machine and a process unit of the image forming machine.

[0005]

According to the present invention, in order to achieve the above main technical problems, the present invention sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area. A photosensitive drum, a charger arranged in the charging area to charge the peripheral surface of the photosensitive drum to a specific polarity, and a peripheral surface of the photosensitive drum in the developing area arranged in the developing area. A developing device that develops the electrostatic latent image formed on the toner image into a toner image, and a transfer unit that is disposed in the transfer area and transfers the toner image formed on the peripheral surface of the photosensitive drum to a transfer paper. In the image forming machine, the charging area is defined on the lower side of the photosensitive drum, and a foreign matter collecting brush is provided between the charging area and the transfer area, the brush being in contact with the peripheral surface of the photosensitive drum. , Between the charger arranged in the charging area and the foreign matter collection brush The toner intrusion prevention wall is provided so that the upper end is close to the peripheral surface of the photosensitive drum, and the toner invasion prevention wall is formed of a film member, and is attachable to and detachable from the grid holding member that constitutes the charger. There is provided an image forming machine characterized by being mounted on a grid member mounted on. Further, according to the present invention, the photosensitive drum which is rotatably arranged and sequentially passes through the charging area, the electrostatic latent image forming area, the developing area and the transfer area, and the photosensitive drum which is arranged in the charging area. A charger for charging the peripheral surface to a specific polarity, and a developing device disposed in the developing area for developing the electrostatic latent image formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area into a toner image. A transfer unit for transferring the toner image formed on the peripheral surface of the photoconductor drum to the transfer paper, the transfer region being defined in the lower side of the photoconductor drum. In an image forming machine provided with a foreign matter collecting brush that comes into contact with the peripheral surface of the photosensitive drum between the charging area and the transfer area, the charger and the foreign matter collecting brush arranged in the charging area. Between the toner and the peripheral surface of the photosensitive drum, the upper end of which is disposed close to An image forming method, comprising: a stop wall, the toner intrusion prevention wall being formed of a film member, and being attached to a grid holding member to which the grid member constituting the charger is detachably attached. Machine is provided.

Further, according to the present invention, a photosensitive drum which is rotatably disposed and sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a lower side of the photosensitive drum. And a charger for charging the peripheral surface of the photoconductor drum to a specific polarity, which is disposed in the charging area, and formed in the peripheral surface of the photoconductor drum in the electrostatic latent image forming area, disposed in the developing area. Image forming machine in which a developing device for developing the electrostatic latent image into a toner image and a foreign matter collecting brush arranged between the charging area and the transfer area and contacting the peripheral surface of the photosensitive drum are unitized. In the process unit of
A photosensitive drum that sequentially passes through an electrostatic latent image forming area, a developing area, and a transfer area, and a peripheral surface of the photosensitive drum, which is arranged in the charging area defined below the photosensitive drum, has a specific polarity. A charging device for charging, a developing device disposed in the developing area for developing the electrostatic latent image formed on the peripheral surface of the photosensitive drum into a toner image in the electrostatic latent image forming area, the charging area and the developing area. In a process unit of an image forming machine in which a foreign matter collecting brush arranged between the transfer area and in contact with the peripheral surface of the photoconductor drum is unitized, the charger and the foreign matter collecting arranged in the charging area A toner intrusion prevention wall is provided, the upper end of which is arranged close to the peripheral surface of the photosensitive drum between the brush and the toner intrusion prevention wall, and the toner intrusion prevention wall is formed of a film member and constitutes the charger. A grid that is detachably attached to the grid holding member. Member is mounted, the process unit of the image forming apparatus is provided, characterized in that. Further, according to the present invention, the photosensitive drum which is rotatably disposed and sequentially passes through the charging area, the electrostatic latent image forming area, the developing area and the transfer area, and the photosensitive drum defined on the lower side of the photosensitive drum. A charger arranged in the charging area for charging the peripheral surface of the photosensitive drum to a specific polarity, and an electrostatic charger formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area arranged in the developing area. A process unit of an image forming machine in which a developing device for developing a latent image into a toner image and a foreign matter collecting brush arranged between the charging area and the transfer area and contacting the peripheral surface of the photosensitive drum are unitized. At the upper end of the peripheral surface of the photosensitive drum between the charger and the foreign matter collecting brush disposed in the charging area. The prevention wall is formed of a film member,
A process unit of an image forming machine is provided, which is mounted on a grid holding member that detachably mounts a grid member that constitutes the charger.

[0007]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an image forming machine constructed according to the present invention will be described in detail below with reference to the accompanying drawings. In the illustrated embodiment, a printer will be described as an example of an image forming machine configured according to the present invention.

FIG. 1 schematically shows an embodiment of a printer constructed according to the present invention. Printer 2
Is a small-sized low-speed laser printer used as a printing device such as a word processor in this embodiment, and is a machine housing 20 molded of synthetic resin.
It is equipped with. The machine body housing 20 includes a box-shaped housing body 21 having an open upper side, and a cover 23 rotatably mounted on a shaft 22 arranged at an upper portion of the housing body 21. The process unit 4 is detachably attached to a substantially central portion of the machine housing 20 configured as described above.

As shown in FIG. 2, the process unit 4 includes a photoconductor unit 40 and a developing unit 50 which is swingably supported by the photoconductor unit 40 via a support shaft 5.
It has and. The photoconductor unit 40 includes a photoconductor support means 41. The photoconductor support means 41 has a pair of side wall members 411 (only the back side wall member in FIG. 2 is spaced apart in the front-rear direction). Shown), and a connecting member 412 for connecting the lower portions of the pair of side wall members 411, respectively.
a, 412b. The connecting members 412a and 412b have inner surfaces facing each other arranged in parallel with each other, and a charging device mounting space 41 in which a charging device to be described later is arranged therebetween.
2c is formed. This charger mounting space 412c is
It is located opposite to a charging area described later. The photoconductor supporting means 41 configured as described above is integrally formed of synthetic resin. Supporting portions 413 each having a mounting hole 414 are provided at the upper ends of the pair of side wall members 411 forming the photosensitive member supporting means 41 on the developing unit 50 side. By inserting the support shaft 5 made of a metal rod disposed in the developing housing of the developing unit 50, which will be described later, into the mounting hole 414 provided in the supporting portion 413, the photoconductor unit 40 and the developing unit 50 are mutually connected. It is swingably supported by.

The photoconductor unit 40 includes a photoconductor drum 42 having a photoconductive layer formed on its peripheral surface. The photosensitive drum 42 is provided with a rotating shaft 421, which is rotatably supported by a pair of side wall members 411 forming the photosensitive member supporting means 41, and is driven by a driving means (not shown) in a direction indicated by an arrow. That is, the charging area 422, the electrostatic latent image forming area 423, the developing area 424, and the transfer area 425 are sequentially driven to rotate. Charged area 422
In the charging means mounting space 412c located at, a charging device 43 is mounted to face the lower peripheral surface of the photosensitive drum 42. In the illustrated embodiment, the charger 43 is composed of a charging corona discharger arranged in parallel with the photosensitive drum 42 along the axial direction, and holds the grid member 431 and the grid member 431. The grid holding member 432 is made of synthetic resin, and the grid member 43 is detachably attached to the grid holding member 432. Charging means 4 configured in this way
3, the grid holding member 432 is the charging device mounting space 4
It is positioned at a predetermined position by being fitted and attached to 12c. In addition, the charging area 422 and the transfer area 425 are
A foreign matter collection brush 44 that comes into contact with the peripheral surface of the photoconductor drum 42 is arranged along the axial direction of the photoconductor drum 42. The paper dust collecting brush 44 is made of acrylic fiber or the like and has a length substantially the same as the axial length of the photosensitive drum 42. The paper dust collecting brush 44 is integrally formed with the grid holding member 432 and extends in the axial direction of the photosensitive drum 42. The brush supporting member 440 is mounted on the brush supporting member 440. In the illustrated embodiment, the upper end of the grid holding member 432 approaches the peripheral surface of the photosensitive drum 42 between the charging corona discharger 431 arranged in the charging area 422 and the foreign matter collecting brush 44. Thus, the toner intrusion prevention wall 47 is formed. The toner intrusion prevention wall 47 is attached to the peripheral surface of the photosensitive drum 42 and is removed by the foreign matter collecting brush 44 together with foreign matter such as paper dust. In addition, it has a function of preventing the intrusion onto the charging corona discharger 431. If the upper end of the toner intrusion prevention wall 47 is in contact with the peripheral surface of the photosensitive drum 42, the residual toner adhering to the peripheral surface of the photosensitive drum 42 may be scraped off. It is desirable that the upper end of 47 be as close as possible without contacting the peripheral surface of the photosensitive drum 42. According to the experiments conducted by the present inventors, the toner intrusion prevention wall 47
1.0 mm between the upper edge of the
It has been found that by positioning with a gap of about 2.0 mm, it is possible to reliably prevent the toner scraped by the foreign matter collecting brush 44 from entering the charging corona discharger 431 side. The toner scraped off by the foreign matter collection brush 44 and blocked from moving toward the charging corona discharger 431 by the toner intrusion prevention wall 47 is accumulated on a horizontal piece of the brush support member 440 near the toner intrusion prevention wall 47. Will be done.

Next, another embodiment of the toner intrusion prevention wall will be described with reference to FIG. The toner intrusion prevention wall 470 shown in FIG. 3 is formed of a film member having a flexible elasticity such as a polyethylene terephthalate (PETP) resin film, and the lower end portion thereof is a grid member 431 which constitutes the charging corona discharger. It is attached by a fixing means such as an adhesive or a double-sided adhesive tape. Therefore, the film member forming the toner intrusion prevention wall 470 is attached to and detached from the grid holding member 432 together with the grid member 431. The grid member 43
In the state where 1 is mounted on the grid holding member 432, the upper end of the film member forming the toner intrusion prevention wall 470 is 1.0 mm to the peripheral surface of the photosensitive drum 42.
It is positioned with a gap of about 2.0 mm. As in the embodiment shown in FIG. 3, the toner intrusion prevention wall 470 is formed of a film member, and the charging corona discharger 43 is formed.
By using a configuration in which the grid member 431 constituting the above is mounted with an adhesive or a double-sided adhesive tape or the like, it becomes easy to manage the gap with the peripheral surface of the photosensitive drum 42. The film member forming the toner intrusion prevention wall 470 is the grid member 4 forming the charging corona discharger 43.
It may be attached to a grid holding member 432 that holds 31.

Between the pair of side wall members 411 forming the photoconductor supporting means 41, the transfer paper fed from diagonally upper left in FIG. 2 is directed to the transfer area 425 on the peripheral surface of the photoconductor drum 42. A lower guide plate 451 that constitutes one of the pre-transfer guide plate pair 45 that guides by means of is provided. The lower guide plate 451 is integrally formed with the pair of side wall members 411. On the upper surface of the lower guide plate 451, a plurality of guide ribs 451a are integrally formed at intervals in the longitudinal direction (direction perpendicular to the paper surface in FIG. 2). In addition, the lower guide plate 451 has a plurality of reinforcing ribs 45 on the lower surface at intervals in the longitudinal direction (direction perpendicular to the paper surface in FIG. 2).
1b is integrally formed, and the reinforcing rib 451b is configured to come into contact with the support shaft 5. Therefore,
Even if a pressing force acts on the upper surface of the lower guide plate 451 and the lower guide plate 451 tries to bend, the reinforcing rib 451b can be prevented from coming into contact with the support shaft 5 and causing the bend. Also, the lower guide plate 451
Is a pair of side wall members 41 constituting the photoconductor supporting means 41.
1 functions as a connecting member that connects the upper portions of the photosensitive member 1 to each other, and the rigidity strength of the photoconductor 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 is highly accurate. Can be maintained at. The lower guide plate 4 in the illustrated embodiment
51 also functions as a member for preventing contact with the photosensitive layer of the photosensitive drum 42 when the process unit 4 is attached and detached, and also as a member for preventing contact with the developing roller of the developing unit 50, which will be described later. It also has a function of preventing the toner scattered from the surface of the roller from adhering to the transfer paper or the transfer paper conveyance path.

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 integrally formed with the pair of side wall members 411. Therefore, the post-transfer guide plate 46 functions as a connecting member that connects the pair of side wall members 411 forming the photoconductor supporting unit 41 to each other, and the rigidity strength of the photoconductor supporting unit 41 can be improved. The post-transfer guide plate 4 in the illustrated embodiment
6 can also function as a contact prevention 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 that accommodates a developer including one-component toner. The developing housing 51 includes a bottom wall 511 and front and rear side walls 512 (see FIG. 2) which are formed to stand upright from the front and rear ends of the bottom wall 511 (ends in the direction perpendicular to the paper surface in FIG. 2).
(Only the rear side wall is shown in FIG. 3) and a left side wall 513, which are integrally molded of synthetic resin and define a stirring chamber 514 and a developing chamber 515. The bottom wall 511 forming the developing housing 51 has a stirring chamber 51.
4 and the developing chamber 515 are integrally formed with a partition wall 516 provided in the front-rear direction (direction perpendicular to the paper surface in FIG. 2). Both left and right sides of the partition wall 516 are formed into arc-shaped guide surfaces 516a and 516b. Between the front and rear side walls 512 constituting the developing housing 51, a connecting member 517 disposed on the upper side of the developing chamber 515 side is provided, and is integrally formed on the front and rear side walls 512. A toner supply hole 518 is formed in the rear side wall 512 which constitutes the developing housing 51.
8 is fitted with a cap 519. The support shaft 5 is disposed at the upper end of the developing housing 51 on the side of the developing chamber 515 having the above-described structure so as to pass through the front and rear side walls 512, and the photoconductor unit 4 is provided at both ends of the support shaft 5.
0 of the pair of side wall members 41 constituting the photosensitive member support means 41
By fitting the mounting hole 414 provided in the first supporting portion 413, the photoconductor unit 40 and the developing unit 50 are swingably supported with respect to each other. The photoconductor unit 4
0 lower end of the photoconductor supporting means 41 and the developing housing 51
A coil spring 52, which is a spring means, is interposed between the lower end of the photoconductor and the front end and the rear end of the photoconductor support means 41 and the developing housing 5.
1 are urged so that they are pulled toward 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 side of the photoconductor unit 40.

In the developing housing 51, a developing roller 53, a replenishing roller 54, a stirring means 55 and a developer regulating means 56 are arranged. The developing roller 53 is
A rotary shaft 531 arranged 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. And 532 are included. The rotating shaft 531 can be formed of a suitable metal material such as stainless steel. Solid synthetic rubber roller 53
Reference numeral 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
The surface roughness of the peripheral surface of 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. Further, 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 thus configured is exposed through the right side opening formed in the developing housing 51 to expose the photosensitive drum 42.
Positioned opposite to. The peripheral surface of the roller 532 that constitutes the developing roller 53 is brought into pressure contact with the peripheral surface of the photosensitive drum 42 in the developing area, and the peripheral surface of the roller 532 is slightly elastically compressed in the pressed nip portion. ing. Rotating shaft 53 of developing roller 53
1 is rotationally driven from the lower side to the upper side in a developing area which is a contact portion between the roller 532 and the photosensitive drum 42 by a driving means (not shown). The rotation of the rotating shaft 531 causes the roller 532 to rotate.
Is also rotationally driven in the direction indicated by the arrow, and the peripheral surface of the roller 532 is moved sequentially in the developer holding area 533, the developer regulating area 534 and the developing area 424. In the illustrated embodiment, a constant voltage of 300 V is applied to the rotary 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. Axis 541,
It includes a roller 542 fixed to the outer peripheral surface of the rotating shaft 541. The rotary shaft 541 can be formed of an appropriate metal material such as stainless steel, like the rotary shaft 531 of the developing roller 53. The roller 542 is made of foam such as foam silicon or foam urethane. The roller 542 is the roller 5 of the developing roller 53 in the developer holding area 533 which is a nip portion with the developing roller 53.
It is pressed against 32. Roller 54 of supply roller 54
The hardness of the foam forming 2 is considerably smaller than the hardness of the roller 532 forming the developing roller 53 (for example, Asker C hardness is about 35), 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 region. Also, the 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 rotationally driven from the upper side to the lower side in a developer holding area 533 which is a nip portion between the roller 542 and the roller 532 of the developing roller 53 by a driving unit (not shown). Be punished. Rotating shaft 5
By the above rotation of 41, the roller 542 is also rotationally driven in the direction indicated by the arrow. In the illustrated embodiment,
The developing roller 53 is attached to the rotation shaft 541 of the supply roller 54.
A constant voltage of 450 V, which is higher than the applied voltage to, 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 to have 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
1.2V1 ≦ V2 ≦ 2.5V1 is set, and the peripheral speed V2 of the developing roller 53 and the peripheral speed V3 of the supply roller 54 are set.
The relationship with is set to 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, which causes a decrease in image density. Further, when the peripheral speed V2 of the developing roller 53 becomes 1.2 V1 or less, the scraping action of the developing roller 53 on the non-transfer developer adhering to the photosensitive drum 42 after transfer is reduced, so that the non-transfer developer is removed. This causes so-called offset fogging that occurs because the toner cannot be removed from the photoconductor drum 42. On the other hand, when the peripheral speed V2 of the developing roller 53 is 2.5 V1 or more, the driving torque of the developing roller 53 increases and the developer scatters due to the 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 replenishing roller 54 has a weak scraping effect on the peripheral surface of the developing roller 53, and therefore, when the non-transferred developer adhering to the photosensitive drum 42 adheres to the developing roller 53 after transfer, It becomes difficult to remove the adhering developer, and the adhering 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
As the driving torque of the developer increases, the tendency of the developer to stay above the nip portion between the replenishing roller 54 and the developing roller 53 becomes strong, which causes insufficient supply of the developer to the developing roller 53.

A stirring means 55 is arranged in the stirring chamber 514 of the developing housing 51. The stirring means 55
Is disposed in parallel with the replenishing roller 54, is rotatably mounted on the front and rear side walls 512 constituting the developing housing 51, and a stirring member 552 fixed to the rotating shaft 551. It includes an elastic stirring sheet member 553 attached to the stirring member 552.
The stirring member 552 is made of synthetic resin,
A plurality of openings are provided in the longitudinal direction (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) is made of resin, and is fixed to the tip edge of the stirring member 552 with an adhesive or the like. The stirring means 55 configured in this manner is continuously driven to rotate in the direction indicated by the arrow in FIG. 2 by a driving means (not shown).

The developer regulating means 56 is provided with a blade 561 having a flexible elasticity which is brought into pressure contact with the peripheral surface of the roller 532 which constitutes the developing roller 32.
The blade 561 has a thickness of 0.1 to 0.2 mm, for example.
The developing roller 53 is made of a stainless steel plate or a spring steel plate, and has substantially the same longitudinal dimension as the length of the roller 532 forming the developing roller 53. Blade 561
Is a bottom wall 5 whose base end constitutes the developing housing 51.
11 is attached to the blade attachment portion 511a provided at the open end of the photoreceptor unit 40 side. That is, the blade 561
The base end portion of the blade mounting portion 511a and the pressing plate 562
It is clamped by and fixed by a screw 563. The tip of the blade 561 is formed in a bent shape, and this bent portion is configured to be pressed against the peripheral surface of the roller 532 forming the developing roller 53 in the developer regulation area 534.

A lid 57 is attached to the developing housing 51 to cover the opened upper portion. The lid 57 is made of synthetic resin, and is fixed to the upper surfaces of the front and rear side walls 512, the left side wall 513, and the connecting member 517, which form the developing housing 51, with an adhesive. A regulating portion 571 is integrally formed on the inner surface of the lid 57 at a position facing the replenishing roller 54, extending in the front-rear direction (direction perpendicular to the paper surface in FIG. 2) and projecting to the developing chamber 515 side. A predetermined gap is provided between the lower end of the restriction portion 571 and the outer peripheral surface of the roller 542 that constitutes the replenishing roller 54. In the illustrated embodiment, the sheet-shaped sealing member 58 is attached to the connecting member 517 that constitutes the developing housing 51. The sheet-shaped sealing member 58 is made of, for example, polyethylene terephthalate (P
It is made of a flexible elastic sheet member such as ETP resin and has a length substantially the same as the axial length of the roller 532 constituting the developing roller 53. The sheet-like seal member 58 has one end portion thereof connected to the connecting member 517.
The roller 53 is fixed to the developing roller 53 by a fixing means such as an adhesive, and the other end is curved to form the developing roller 53.
It is elastically brought into contact with the peripheral surface of 2. The sheet-like seal member 58 thus configured is provided with the blade 561 of the developer regulating means 56 together with the developing housing 5.
The developer is prevented from scattering from the opening of the first photosensitive member unit 40 side.

The process unit 4 configured as described above is detachably mounted in the machine housing 20 of the printer 2 as shown in FIG. That is, by turning the cover 23 constituting the machine housing 20 of the printer 2 around the shaft 22 in the counterclockwise direction in FIG. 1, the upper part of the housing main body 21 constituting the machine housing 20 is opened. Next, the process unit 4 is mounted in the housing body 21 from above. The housing body 21
Positioning means (not shown) for mounting the photoconductor unit 40 of the process unit 4 at a predetermined position is provided therein. The process unit 4 in the body housing 20
Once installed on the housing body 21 of the
By turning clockwise two times in FIG. 1, the upper part is closed.

As shown in FIG. 1, at the bottom of the housing body 21 which constitutes the body housing 20 of the printer 2,
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 to electrostatically discharge the photosensitive layer. Form a latent image. Further, a fixing roller pair 25 is arranged on the downstream side of the post-transfer guide plate 46 in a housing main body 21 constituting the machine housing 20 of the printer 2, and a discharge roller pair 26 is arranged on the downstream side of the fixing roller pair 25. Is provided. Further, a paper discharge tray 27 is arranged on the downstream side of the discharge roller pair 26.

A cover 23, which constitutes the machine housing 20 of the printer 2, is provided with a paper feed tray 28 on the upper left side in FIG. A paper feed roller 29 is disposed on the downstream side of the paper feed tray 28,
The paper feed roller 29 is rotationally driven in the direction shown by the arrow in FIG. A friction pad 30 for separating the sheet is arranged so as to face the sheet feeding roller 29. Further, in the transfer area 422, a non-contact type transfer roller 31 is arranged so as to face the photosensitive drum 42. The transfer roller 31 is made 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 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 done,
Therefore, the transfer roller 31 is slid and driven by the rotation of the photosensitive drum 42. The gap between the peripheral surface of the transfer roller 31 and the peripheral surface of the photosensitive drum 42 is 0.5 m.
It is set to about m. A constant current of, for example, 10 μA is applied to the transfer roller 31 thus configured.
The cover 23 is provided with an upper guide plate 452 which constitutes the other of the pre-transfer guide plate pair 45.

The printer 2 in the illustrated embodiment is configured as described above, and its operation will be described below. The above-mentioned members start operating based on a print command from a word processor (not shown) or the like, and the charging corona discharger 4
By 3, the surface photosensitive layer of the photosensitive drum 42 is substantially uniformly charged to a specific polarity. Next, the surface of the charged photosensitive layer of the photosensitive drum 42 is irradiated with laser light corresponding to print data from a word processor or the like from the laser unit 24, 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 action of the developing unit 50. Regarding the developing action of the developing unit 50,
It will be described in detail later. On the other hand, the transfer papers placed on the paper feed tray 28 are fed one by one by the action of the paper feed roller 29 and the friction pad 30. Then, the transfer paper is guided by the pre-transfer guide plate pair 45 and the photosensitive drum 42 and the transfer roller 3
The toner image formed on the photosensitive drum 42 is transferred onto the surface of the photosensitive drum 42. The transfer sheet onto which the toner image has been transferred is guided by the post-transfer guide plate 46 and conveyed to the fixing roller pair 25. The transfer paper on which the toner image is heated and fixed by the fixing roller pair 25 is discharged onto the paper discharge tray 27 by the discharge roller pair 26. On the other hand, when the peripheral surface of the photoconductor drum 42 that has passed through the transfer area 425 passes through the foreign matter collecting brush 44, foreign matter such as paper dust attached to the circumferential surface is removed by the foreign matter collecting brush 44. At this time, a part of the residual toner adhering to the peripheral surface of the photoconductor drum 42 is removed together with the foreign matter such as paper dust. The removed residual toner may fall without being reliably captured by the foreign matter collection brush 44. When the dropped toner accumulates on the grid member 431 of the charging corona discharger 43, it causes charging unevenness. In the illustrated embodiment, the toner intrusion prevention wall 47 (470) prevents the falling toner from falling on the grid member. Invasion to the 431 side is prevented. The residual toner attached to the peripheral surface of the photoconductor drum 42 that has passed through the foreign matter collection brush 44 is collected by the developing roller 53.

Next, the developing action of the developing unit 50 will be described. By starting the operation of the developing unit 50,
The developing roller 53, the replenishing roller 54 and the stirring means 5
5 are rotationally driven in the directions indicated by arrows by driving means (not shown). Stirring member 55 that constitutes 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 is stirred and passes over the partition wall 516 to replenish the supply roller 54.
Is supplied into the developing chamber 514 from above. At this time, due to the restriction portion 571 formed on the inner surface of the lid 57,
The amount of developer supplied into the developing chamber 514 is limited so as not to become excessive. The developer thus supplied by the agitating means 55 rides on the roller 542 of the replenishing roller 54 and is conveyed to the nip portion which is the developer holding area 533 with the roller 532 of the developing roller 53. Since the replenishing roller 54 and the developing roller 53 both rotate 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, the replenishing roller 54 and the developing roller 53 move in the same direction.
The developer is sufficiently supplied to the developer, and the shortage of the developer can be prevented. Further, the supply roller 54 and the developing roller 5
3 is the developer holding area 533 which is the nip portion as described above.
Since they rotate in the same direction, they can be surely driven without requiring a large driving force.

As described above, the developer conveyed to the developer holding area 533, which is the nip portion between the replenishing roller 54 and the developing roller 53, constitutes the developing roller 53.
It is held on the peripheral surface of No. 2 and conveyed toward the developer regulation area 534. At this time, the supply roller 54 and the developing roller 53
As described above, both rotate in the same direction from the upper side to the lower side in the developer holding area 533 which is the nip portion, so that the developer is held by the developing roller 53 through both the nip portions and is held in the developer regulating area. Since it is transported to the developing area 524 and the developing area 424, it is sufficiently charged by being rubbed against each other when passing through the nip portion, so that so-called fogging is prevented.

In the developer regulation area 534, the blade 561 of the developer regulation means 56 acts on the developer retained on the peripheral surface of the roller 532 of the developing roller 53 to be retained on the peripheral surface of the roller 532. The developer is regulated to the required amount to form a thin layer. The developer regulated by the blade 561 of the developer regulation means 56 in the developer regulation area 534 and scraped off on the bottom wall 511 of the developing housing 51 is rotated by the replenishing roller 54 in the direction indicated by the arrow. The partition wall 516
The sheet is conveyed along the guide surface 516b. It is collected by the developing roller 53 in the developing area 424.

As described above, it is held on the peripheral surface of the roller 532 constituting the developing roller 53 in the developer holding area 533, and is formed into a thin layer in the developer controlling area 534 by the action of the blade 561 of the developer controlling means 56. The developer thus developed is rotated in the developing area 424 along with the rotation in the direction of the arrow.
Be transported to. In the developing area 424, a developer is applied to the electrostatic latent image on the electrostatic photoconductor disposed on the peripheral surface of the photoconductor drum 42, and 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 an image area charged to about +120 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 the direction shown by the arrow in FIG. 2, and therefore, in the developing area 424, the peripheral surface of the photosensitive drum 42 and the roller 5 forming the developing roller 53.
Together with the peripheral surface of 32, they are moved in the same direction from below to above. The peripheral speed V2 of the roller 532 and the photosensitive drum 4
Since the peripheral speed V1 of 2 is set to 1.2V1 ≦ V2 ≦ 2.5V1, sufficient developer is conveyed to the developing area 424 by the roller 532 of the developing roller 53, and the peripheral speed of the photosensitive drum 42 is increased. By the rubbing action of the peripheral surface of the roller 532 against the surface, the developer once attached to the non-image portion of the electrostatic latent image is appropriately peeled off, and thus a good toner image having an appropriate developing density and no fog is formed. Obtainable. On the other hand, the roller 532 that constitutes the developing roller 53
The used developer that has been held on the peripheral surface of the developing roller 53 and has passed 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. Since the peripheral speed of the replenishing roller 54 is set to be higher than the peripheral speed of the developing roller 53, the developer is moved in the nip portion. It is possible to weaken the adhesive force of the transfer developer and collect it, so that it is possible to prevent the occurrence of so-called ghost caused by the non-transfer developer attached to the developing roller 53.

Although the present invention has been described based on the embodiment applied to a printer, the present invention is not limited to the illustrated embodiment, and can be applied to an electrostatic copying machine, for example. Various variations or modifications are possible without departing from the scope of the technical idea of.

[0031]

Since the image forming machine and the process unit of the image forming machine according to the present invention are configured as described above, the following operational effects are achieved.

That is, according to the present invention, a foreign matter collecting brush which comes into contact with the peripheral surface of the photosensitive drum is provided between the charging area defined on the lower side of the photosensitive drum and the transfer area. In a process unit of an image forming machine or an image forming machine, in which a foreign matter collecting brush that comes into contact with the peripheral surface of the photosensitive drum is provided between the charger and the foreign matter collecting brush. Even if the residual toner removed by the foreign matter collection brush along with the foreign matter such as paper dust is not reliably captured by the foreign matter collection brush, it is equipped with a toner intrusion prevention wall that is arranged with its upper end close to the surface. The toner entry prevention wall prevents falling toner from entering the charger side. Therefore, it is possible to prevent the occurrence of problems such as uneven charging caused by the accumulation of toner on the upper surface of the charger.

Further, according to the present invention, the toner intrusion prevention wall is formed of a film member and is attached to the grid member which constitutes the charger or the grid holding member which holds the grid member. It becomes easy to manage the gap between the body drum and the peripheral surface.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an embodiment of an image forming machine configured according to the present invention.

FIG. 2 is a sectional view of an image forming machine configured according to the present invention shown in FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the toner intrusion prevention wall included in the image forming machine shown in FIG.

[Explanation of symbols]

2: Printer 4: Process unit 5: Support shaft 20: Airframe housing 21: Housing body 23: Cover 24: Laser unit 25: Pair of fixing rollers 26: Ejection roller pair 27: Output tray 28: Paper feed tray 29: Paper feed roller 30: Friction pad 31: Transfer roller 40: Photoconductor unit 41: Photoreceptor support means 42: photoconductor drum 43: Charger (corona discharger for charging) 44: Foreign object collection brush 45: Pre-transfer guide plate pair 46: Post-transfer guide plate 47: Toner intrusion prevention wall 50: Development unit 51: Development housing 52: Coil spring 53: developing roller 54: Supply roller 55: stirring means 56: developer control means 57: Lid 58: Sheet-shaped sealing member 431: Grid member for charging corona discharger 411: Side wall member of photoconductor supporting means 412: Connection member for photoconductor supporting means 422: charged area 423: electrostatic latent image forming area 424: Development area 425: Transfer area 470: Toner intrusion prevention wall 514: stirring chamber 515: Development room 517: Connecting member of developing housing 533: developer holding area 534: Developer regulated area 561: blade

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 64-50089 (JP, A) JP 4-267282 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 21/00 G03G 21/10-21/12 G03G 15/02-15/02 103 G03G 15/00 550 G03G 21/16-21/18

Claims (4)

(57) [Claims] 1. A photosensitive drum which is rotatably arranged and sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a peripheral surface of the photosensitive drum which is arranged in the charging area. A charger for charging to a specific polarity, a developing device arranged in the developing area for developing an electrostatic latent image formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area into a toner image, and the transfer device. A transfer means for transferring a toner image formed on the peripheral surface of the photosensitive drum to a transfer paper, the charging area being defined below the photosensitive drum, In an image forming machine provided with a foreign matter collecting brush which comes into contact with the peripheral surface of the photosensitive drum between the transfer area and the transfer area, between the charger and the foreign matter collecting brush arranged in the charging area. At the top of the toner drum, a toner intrusion prevention wall is arranged with its upper end close to the peripheral surface of the photosensitive drum. And Bei, preventing the toner invasion
The wall is formed by a film member, and the charger is
A grease that is detachably attached to the constituent grid holding members.
An image forming machine, characterized in that the image forming machine is mounted on a head member . 2. A photosensitive drum which is rotatably arranged and sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a peripheral surface of the photosensitive drum which is arranged in the charging area. A charger for charging to a specific polarity, a developing device arranged in the developing area for developing an electrostatic latent image formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area into a toner image, and the transfer device. A transfer means for transferring a toner image formed on the peripheral surface of the photosensitive drum to a transfer paper, the charging area being defined below the photosensitive drum, In an image forming machine provided with a foreign matter collecting brush which comes into contact with the peripheral surface of the photosensitive drum between the transfer area and the transfer area, between the charger and the foreign matter collecting brush arranged in the charging area. At the top of the toner drum, a toner intrusion prevention wall is arranged with its upper end close to the peripheral surface of the photosensitive drum. And Bei, preventing the toner invasion
The wall is formed by a film member, and the charger is
A grid holder that detachably mounts the constituent grid members.
An image forming machine mounted on a holding member . 3. A photosensitive drum which is rotatably arranged and sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and the charging area defined below the photosensitive drum. A charger arranged to charge the peripheral surface of the photosensitive drum to a specific polarity, and an electrostatic latent image formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area arranged in the developing area. In a process unit of an image forming machine, a developing device for developing a toner image and a foreign matter collecting brush arranged between the charging area and the transfer area and contacting a peripheral surface of the photosensitive drum are unitized. The toner intrusion prevention wall is provided between the charging device disposed in the charging area and the foreign matter collecting brush, the toner intrusion prevention wall having an upper end disposed close to the peripheral surface of the photosensitive drum.
The wall is formed by a film member, and the charger is
A grease that is detachably attached to the constituent grid holding members.
A process unit of an image forming machine, characterized in that the process unit is mounted on a head member . 4. A photosensitive drum which is rotatably arranged and sequentially passes through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and the charging area defined below the photosensitive drum. A charger arranged to charge the peripheral surface of the photosensitive drum to a specific polarity, and an electrostatic latent image formed on the peripheral surface of the photosensitive drum in the electrostatic latent image forming area arranged in the developing area. In a process unit of an image forming machine, a developing device for developing a toner image and a foreign matter collecting brush arranged between the charging area and the transfer area and contacting a peripheral surface of the photosensitive drum are unitized. The toner intrusion prevention wall is provided between the charging device disposed in the charging area and the foreign matter collecting brush, the toner intrusion prevention wall having an upper end disposed close to the peripheral surface of the photosensitive drum.
The wall is formed by a film member, and the charger is
A grid holder that detachably mounts the constituent grid members.
A process unit of an image forming machine , which is mounted on a holding member .