KR19980018906A - IMAGE-FORMING MACHINE AND PROCESS UNIT ADAPTED THERETO - Google Patents

Abstract

A photosensitive drum 42 sequentially passing through the charging region 422, the electrostatic latent image forming region 423, the developing region 424, and the transfer region 425, and the charger 43 disposed in the charging region 422. And a developing apparatus 50 arranged in the developing region 424 and a transfer means arranged in the transfer region 425, and a charging region 422 is defined below the photosensitive drum 42, An image forming machine in which a foreign matter recovery brush 44 is disposed between the 422 and the transfer area 425 in contact with the circumferential surface of the photosensitive drum 42, and the charger 43 and the foreign matter recovery brush 44 are disposed. The toner penetration preventing wall 47 is disposed so that its upper end approaches the circumferential surface of the photoconductive drum 42 between and.

Description

Image forming machine and process unit applied thereto

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for developing an electrostatic latent image formed on a photosensitive layer of a photosensitive drum such as an electrostatic copying machine and a laser printer to a toner image, and transferring the toner image onto a transfer sheet, and a process unit applied thereto. .

This type of image forming machine has a photosensitive drum which is freely rotated and passes sequentially through a charging area, an electrostatic latent image forming area, a developing area and a transfer area, and a charging which is disposed in the charging area and charges a specific polarity on the circumferential surface of the photosensitive drum. And a developing apparatus for developing the electrostatic latent image formed on the circumferential surface of the photosensitive drum in the electrostatic latent image forming region as a toner image, and the toner image disposed on the circumferential surface of the photosensitive drum on the transfer paper. And a transfer means.

In the image forming apparatus of this type, the positions of the above-described regions vary depending on whether the transfer paper passes through the upper side or the lower side of the photosensitive drum.

In general, a structure in which a transfer sheet passes through the lower side of the photosensitive drum is used. In this case, since the transfer sheet is located below the photosensitive drum, the charging region is located above the photosensitive drum.

In addition, in the form of the transfer paper passing through the upper side of the photosensitive drum, the transfer area is configured to be located above the photosensitive drum, so that the charging region is located below the photosensitive drum.

In the image forming apparatus in which the toner remaining on the circumferential surface of the photosensitive drum which has passed through the transfer area is recovered by the developing apparatus, foreign substances such as paper powder or the like adhered to the circumferential surface of the photosensitive drum during transfer, etc. If it is collected together with the developing apparatus, the subsequent image quality is deteriorated.

Here, a proposal has been made to arrange a foreign matter recovery brush between the charging region and the transfer region to remove foreign substances such as paper powder adhering to the circumferential surface of the photosensitive drum.

By the way, the foreign matter recovery brush preferably removes only foreign substances such as paper powder and passes the remaining toner attached to the circumferential surface of the photosensitive drum, but it may scrape off the acid toner.

If the scraped residual toner is firmly captured by the foreign matter collection brush, there is no problem. However, most of the toner falls because the toner has fewer particles than foreign substances such as paper powder.

Therefore, in the image forming apparatus in which the charging region is located below the photosensitive drum, the toner scraped off by the foreign matter collection brush is deposited on the upper surface of the charger disposed in the charging region.

If toner accumulates on the upper surface of the charger, charging irregularity occurs, which causes image defects.

An object of the present invention is to configure the charging region to be located below the photosensitive drum, in which residual toner removed together with foreign matter from the circumferential surface of the photosensitive drum is dropped by a foreign matter recovery brush disposed between the charging region and the transfer region. The present invention provides an image forming apparatus and a process unit of an image forming apparatus capable of preventing deposition on a charger disposed in an island charging region.

1 is a front view schematically showing one embodiment of an image former constructed in accordance with the present invention;

FIG. 2 is a sectional view of an image former constructed in accordance with the present invention shown in FIG.

3 is a cross-sectional view showing another embodiment of the toner penetration preventing wall provided in the image forming machine shown in FIG.

* Explanation of symbols for main parts of the drawings

4 process unit, 20 gas housing, 42 photosensitive drum, 43 charger, 44 foreign material recovery brush, 46 post-transfer guide plate, 47, 470: toner penetration barrier, 50 developing device, 422 charging area 423: electrostatic latent image forming area, 424: developing area, 425: transfer area, 431: grid member, 432: grid holding member

In order to achieve the above object, according to the present invention, the rotation is freely arranged, and the photoconductor drum sequentially passes through the charging region, the electrostatic latent image forming region, the developing region and the transfer region, and the peripheral surface of the photosensitive drum disposed in the charging region. A charger for charging to a specific polarity, a developing apparatus for developing an electrostatic latent image formed on the circumferential surface of the photosensitive drum in the developing area and forming the toner image in the electrostatic latent image forming area, and formed on the circumferential surface of the photosensitive drum in the transfer area. An image forming machine having transfer means for transferring a toner image onto a transfer paper, the charging area being defined below the photosensitive drum, and having a foreign matter brush disposed in contact with the circumferential surface of the photosensitive drum between the charging area and the transfer area; A circular table of a photoconductive drum in between a charger disposed in a charging region and a foreign material recovery brush An image forming machine is provided, comprising a toner penetration preventing wall disposed at an upper end of the surface.

Further, according to the present invention, the photosensitive drum is arranged freely in rotation and passes through the charging area, the electrostatic latent image forming area, the developing area, and the transfer area, and the charged area defined below the photosensitive drum, and the circumferential surface of the photosensitive drum is disposed. A charging device for charging with a specific polarity, a developing device for developing an electrostatic latent image formed on the circumferential surface of the photosensitive drum in a developing area and forming a toner image in a developing latent image forming area, and disposed between the charging area and the transfer area, and the photosensitive member. A process unit of an image forming machine in which a foreign matter collection brush in contact with the circumferential surface of a drum is united, wherein the toner disposed so as to have an upper end approaching the circumferential surface of the photosensitive drum between the charger disposed in the charging area and the foreign matter recovery brush. A process unit of an image forming machine is provided, which is provided with an intrusion prevention wall.

Further, according to the present invention, the above-described toner penetration preventing wall is formed by a film member, and is provided in the image forming apparatus or the process unit of the image forming apparatus mounted on the charger holding member for holding the charger.

EXAMPLE

Next, an embodiment of an image forming apparatus constructed in accordance with the present invention will be described in detail with reference to the accompanying drawings.

In addition, in the illustrated embodiment, a printer is described as an example of an image forming apparatus constructed in accordance with the present invention.

1 schematically shows an embodiment of a printer constructed in accordance with the present invention.

The printer 2 is a small-sized low-speed laser printer used as a printing device such as a word processor in the present embodiment, and has a gas housing 20 formed of synthetic resin.

The gas housing 20 includes a box-shaped housing main body 21 having an open upper side and a cover 23 freely rotatable on a shaft 22 disposed above the housing main body 21.

The process unit 4 is freely attached to and detached from the substantially center portion of the gas housing 20 configured as described above.

As shown in FIG. 2, the process unit 4 includes a photosensitive member unit 40 and a developing unit 50 supported by the photosensitive unit unit 40 so as to be able to swing through a support shaft 5.

The photosensitive member unit 40 is provided with the photosensitive member support means 41, and this photosensitive member support means 41 is spaced in the front-back direction, and has a pair of side wall member 411 arrange | positioned (inside side wall in FIG. 2). Only members are shown) and connecting members 421a and 412b for connecting lower portions of the pair of side wall members 411, respectively.

In addition, the connecting members 412a and 412b form a charging means mounting space 412c in which inner surfaces facing each other are arranged in parallel and between which the charging means described later is disposed.

This charging means mounting space 412c is located opposite to the charging region described later.

The photoconductor support means 41 comprised in this way is integrally formed with synthetic resin.

Support portions 413 having mounting holes 414 are provided at the upper ends of the pair of side wall members 411 constituting the photosensitive member support means 41 on the developing unit 50 side.

The photosensitive member unit 40 and the developing unit 50 are inserted into the mounting hole 414 formed in the supporting portion 413 through the support shaft 5 made of the metal rod material disposed in the developing housing described later of the developing unit 50. Are mutually swingable.

The photosensitive member unit 40 is provided with the photosensitive drum 42 in which the photosensitive layer was formed in the circumferential surface.

The photosensitive drum 42 has a rotating shaft 421, the rotation of which is freely supported by a pair of side wall members 411 constituting the photosensitive member supporting means 41, not shown. The driving means is rotated so as to sequentially pass through the direction indicated by the arrow, that is, the charging region 422, the electrostatic latent image forming region 423, the developing region 424, and the transfer region 425.

In the charging means mounting space 412c located in the charging region 422, a charger 43 is disposed facing the lower circumferential surface of the photosensitive drum 42. As shown in FIG.

The charger 43 is constituted by a charging corona discharger arranged in the axial direction in parallel with the photosensitive drum 42 in the illustrated embodiment, and includes a gridmember 431 and a grid member 431. It consists of a grid holding member 432 made of synthetic resin for holding, the grid member 431 is attached to the grid holding member 432 and can be detachably mounted.

The charger 43 configured as described above is positioned at a predetermined position by fitting the grid holding member 432 into the charger mounting space 412c.

Further, between the charging region 422 and the transfer region 425, a foreign matter recovery brush 44 in contact with the circumferential surface of the photosensitive drum 42 is disposed along the axial direction of the photosensitive drum 42. This foreign matter recovery brush 44 is made of acrylic resin or the like, has a length substantially equal to the axial length of the photosensitive drum 42, is formed integrally with the grid holding member 432, and the axial direction of the photosensitive drum 42. It is mounted to the brush support member 440 disposed according to.

In the illustrated embodiment, the upper end of the grid holding member 432 is the circumference of the photosensitive drum 42 between the charging corona discharger 43 and the foreign matter recovery brush 44 disposed in the charging region 422. It protrudes so as to approach the surface, and constitutes the toner intrusion preventing wall 47.

The toner penetration preventing wall 47 is adhered to the circumferential surface of the photosensitive drum 42 so that the residual toner removed together with the foreign matter such as the paper powder by the foreign matter recovery brush 44 is not reliably captured by the foreign matter recovery brush 44. It has a function which prevents invasion on the above-mentioned corona discharger 43 when it falls without a fall.

In addition, if the upper end of the toner penetration preventing wall 47 is in contact with the circumferential surface of the photosensitive drum 42, the residual toner adhering to the photosensitive drum 42 may be scraped off. It is preferable that the upper end of is approached as far as possible without contacting the circumferential surface of the photosensitive drum 42.

According to the experiments of the inventors, the foreign matter recovery brush 44 is located at an interval of about 1.0 mm to 2.0 mm between the upper end of the toner penetration preventing wall 470 and the circumferential surface of the photosensitive drum 42. It has been found that the toner scratched by the toner can be securely prevented from entering the charging corona discharger 43 side.

In addition, the toner that is scraped off by the foreign matter collection brush 44 and blocked by movement of the toner intrusion prevention wall 47 toward the corona discharger 43 for charging is the toner intrusion prevention wall 47 of the brush support member 440. It accumulates in the life part of the vicinity.

Next, another embodiment of the above-described toner penetration preventing wall will be described with reference to FIG.

The toner penetration preventing wall 470 shown in FIG. 3 is formed of a film member having a flexible elasticity, such as a polyethylene terephthalate (PETP) resin film, for example, and a lower end thereof includes a grid member constituting a charging corona discharger ( 431 is adhered to by means of fixing means such as adhesive or double-sided adhesive tape.

Therefore, the film member constituting the toner intrusion preventing wall 470 is attached to and removed from the grid holding member 432 together with the grid member 431.

In addition, the upper end of the film member constituting the toner penetration preventing wall 470 with the grid member 431 mounted to the grid holding member 432 is 1.0 mm to 2.0 mm on the circumferential surface of the photosensitive drum 42. It is positioned at intervals of.

As shown in the embodiment shown in Fig. 3, the toner penetration preventing member 470 is formed of a film member and is mounted on the grid member 431 constituting the corona discharger 43 for charge by adhesive or double-sided adhesive tape. Management of the space | interval with the circumferential surface of the photosensitive drum 42 becomes easy.

In addition, the film member constituting the toner penetration preventing wall 470 may be attached to the grid holding member 432 holding the grid member 431 constituting the charging corona discharger 43.

Between the pair of side wall members 411 constituting the photosensitive member supporting means 41, a pair for guiding the transfer paper supplied to the left inclined upward toward the transfer region 425 on the circumferential surface of the photosensitive drum 42 in FIG. The lower guide plate 451 constituting one side of the pre-transfer guide plate 45 is disposed, and the lower guide plate 451 is formed integrally 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 ground in FIG. 2).

In addition, the lower guide plate 451 is integrally formed with a plurality of reinforcing ribs 451b at intervals in the longitudinal direction (the direction perpendicular to the ground in Fig. 2) on the lower surface, and the reinforcing ribs 451b are formed as described above. It is comprised so that the support shaft 5 may contact.

Accordingly, even if the lower guide plate 451 tries to bend due to the pressure applied to the upper surface thereof, the reinforcing rib 451b abuts against the support shaft 5, thereby preventing the occurrence of warpage.

Further, the lower guide plate 451 functions as a connecting member for interconnecting the upper portions of the pair of side wall members 411 constituting the photosensitive member supporting means 41 and improves the rigidity of the photosensitive member supporting means 41. There is a number.

Again, in the illustrated embodiment, since the lower guide plate 451 is integrally formed with the pair of side wall members 411, the photosensitive drum 42 with which the rotation is freely supported by the pair of side wall members 411 is provided. The positional relationship can be maintained with high accuracy.

In addition, the lower guide plate 451 in the illustrated embodiment also functions as a contact preventing member of the photosensitive drum 42 to the photosensitive layer when the process unit 4 is attached and detached, and the developing unit 50 will be described later. It also functions as a contact preventing member to the developing roller, and also serves to prevent scattering toner from the surface of the developing roller, which will be described later, from being attached to the transfer paper or the transfer path of the transfer paper.

Between the pair of side wall members 411 constituting the photosensitive member support means 41, a post-transfer guide plate 46 for guiding the transfer paper transferred in the transfer area 425 to the fixing means described later is provided. The post-transfer guide plate 46 is formed integrally with the pair of side wall members 411.

Accordingly, the post-transfer guide plate 46 can function as a connecting member for interconnecting the pair of side wall members 411 constituting the photosensitive member supporting means 41 and can improve the rigidity of the photosensitive member supporting means 41.

The post-transfer guide plate 46 in the illustrated embodiment can also function as a contact preventing member of the photosensitive drum 42 against the photosensitive member when the process unit 4 is attached and detached.

Next, the developing unit 50 as the electrostatic latent image developing apparatus will be described.

The developing unit 50 in the illustrated embodiment includes a developing housing 51 in which a developer made of one-component toner is accommodated.

The developing housing 51 is formed of a front wall and a rear wall 512 which are formed by standing up from the bottom wall 511 and the front and rear terminals of the bottom wall (the terminal portion in the direction perpendicular to the ground in Fig. 2). Only the rear side wall is shown in FIG. 2). The left side wall 513 is integrally formed by a synthetic resin and defines a stirring chamber 514 and a developing chamber 515.

The bottom wall 511 constituting the developing housing 51 has a partition wall 516 provided between the stirring chamber 514 and the developing chamber 515 in the front-rear direction (the direction perpendicular to the ground in FIG. 2). It is molded integrally.

The left and right surfaces of the partition wall 516 are formed with arc-shaped guide surfaces 516a and 516b.

A connecting member 517 disposed on the upper side of the developing chamber 515 is provided between the front and back side walls 512 constituting the developing housing 51 and is integrally formed on the front and back side walls 512.

In addition, a toner supply hole 518 is formed in the rear side wall 512 constituting the developing housing 51, and a cap 519 is fitted into the toner supply hole 518.

The support shaft 5 is disposed through the front and rear side walls 512 at the upper end of the developing chamber 51 of the developing housing 51 configured as described above, and the photosensitive member 40 is disposed at both ends of the supporting shaft 5. The photosensitive member unit 40 and the developing unit 50 are allowed to oscillate by fitting to the mounting holes 414 formed in the supporting portion 413 of the pair of side wall members 411 constituting the photosensitive member supporting means 41 of the photosensitive member. Supported.

In addition, between the lower end of the photosensitive member supporting means 41 of the photosensitive member unit 40 and the lower end of the developing housing 51, the coil spring 52 which is a spring means is interposed in the front terminal part and the rear terminal part, respectively. By this coil spring 52, the photosensitive member support means 41 and the developing housing 51 are urged to mutually draw | support the support shaft 5 as a support point.

The developing housing 51 is open above and to the right, that is, at the photosensitive unit 40 side.

In the developing housing 51, the developing roller 53, the supply roller 54, the stirring means 55, and the developer regulating means 56 are disposed.

The developing roller 53 is disposed in the developing chamber 515 of the developing housing 51, and the rotating shaft 531 freely mounted on the front and back side walls 512 constituting the developing housing and the rotating shaft 531. It includes a solid synthetic rubber roller 532 fixed to the outer circumferential surface of the.

The rotating shaft 531 may be formed of a suitable metal material such as stainless steel.

The solid synthetic rubber roller 532 is made of a relatively flexible and conductive material such as a conductive solid synthetic rubber such as urethane rubber.

In the illustrated embodiment, the roughness of the surface of the circumferential surface of the solid synthetic rubber roller 532, that is, the ten point roughness roughness Rz specified in Japanese Industrial Standard (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.

In addition, the roller hardness of the solid synthetic rubber roller 532 is set to 60-80 as the Asker C hardness in the illustrated embodiment.

The roller 532 of the developing roller 53 configured as described above is exposed through the right opening formed in the developing housing 51 so as to face the photosensitive drum 42 described above.

Then, the circumferential surface of the roller 532 constituting the developing roller 53 is in compression contact with the circumferential surface of the photosensitive drum 42 in the developing region, so that the nip of the roller 532 in this compressed contact nip portion The circumferential surface is slightly elastically compressed.

The rotating shaft 531 of the developing roller 53 is driven to rotate from the lower side to the upper side in the direction indicated by the arrow by the driving means (not shown), that is, the developing region which is the contact portion between the roller 532 and the photosensitive drum 42. .

The roller 532 is also rotated in the direction indicated by the arrow by the rotation of the rotating shaft 531, and the circumferential surface of the roller 532 is a developer holding area 533, a developer regulating area 534, and a developing area. 424 will be moved sequentially.

In the illustrated embodiment, a constant voltage of 300 V is applied to the rotation shaft 531 of the developing roller 53.

The supply roller 54 is arranged in parallel with the developing roller 53 in the developing chamber 515 of the developing housing 51, and is freely rotated on the front and back side walls 512 constituting the developing housing 51. The attached rotary shaft 541 and the roller 542 fixed to the outer circumferential surface of the rotary shaft 541 are included.

The rotary shaft 54l can be formed of a suitable metal material such as stainless steel similarly to the rotary shaft 531 of the developing roller 53.

The roller 542 is composed of a foam such as foamed silicone or urethane. The roller 542 is in compression contact with the roller 532 of the developing roller 53 in the developer holding area 533 which is the nip of the developing roller 53.

The hardness of the foam constituting the roller 542 of the supply roller 54 is considerably less than the hardness of the roller 532 constituting the developing roller 53 (for example, about 35 in Asuka C hardness) and the roller ( It is preferable that the roller 542 is elastically compressed in contact with the roller 542 in the nip region by about 0.1 to 0.6 mm in the nip region.

The roller 542 also has conductivity, and its volume resistance is set to about 10 ² to 10 ⁶ Ω · cm.

The rotary shaft 541 of the replenishment roller 54 is a developer holding area 533 in the direction indicated by the arrow by the driving means (not shown), that is, the nip of the roller 542 and the roller 532 of the developing roller 53. It is rotated from the upper side to the lower side.

By the above-mentioned rotation of the rotating shaft 541, the roller 542 is also driven to rotate in the direction shown by the arrow.

In the illustrated embodiment, a constant voltage of 450 V higher than the voltage applied to the developing roller 53 is applied to the rotation shaft 541 of the supply roller 54.

The relationship between the circumferential speed V1 of the photosensitive drum 42, the circumferential speed V2 of the developing roller 53, and the circumferential speed V3 of the supply roller 54 is set to VlV2V3.

In the illustrated embodiment, the relationship between the circumferential speed V1 of the photosensitive drum 42 and the circumferential speed V2 of the developing roller 53 is set to 1.2 V1 ≤ V2 ≤ 2.5 V1, and the circumferential speed V2 of the developing roller 53 is shown. And the relationship with the circumferential speed V3 of the supply roller 54 are set to 1.0 V 2 ≤ V 3 ≤ 2.0 V 2.

When the circumferential speed V2 of the developing roller 53 is 1.2 V1 or less, supply of the developer to the photosensitive member dream 42 becomes insufficient, which causes a decrease in image density.

When the circumferential speed V2 of the developing roller 53 is 1.2 V1 or less, the scraping effect of the developing roller 53 with respect to the non-transfer developer adhered to the photosensitive drum 42 after transfer is reduced. Can be removed from the photosensitive drum 42, so-called offset and blur occurs.

On the other hand, when the circumferential speed V2 of the developing roller 53 becomes 2.5 V1 or more, the driving torque of the developing roller 53 is great and causes the developer to scatter by centrifugal force.

Moreover, when the circumferential speed V3 of the supply roller 54 becomes 1.0 V2 or less, it will become a supply shortage of the developer to the developing roller 53, and will cause the image density to fall.

When the circumferential speed V3 of the supply roller 54 becomes 1.0 V2 or less, the effect of scraping off the circumferential surface of the developing roller 53 by the supply roller 54 is weak. When the developer adheres to the developing roller 53, it becomes difficult to remove this adhesion developer, and this adhesion developer causes so-called ghost phenomenon that appears during the next development.

On the other hand, when the circumferential speed V3 of the supply roller 54 becomes 2.0V2 or more, the drive torque of the supply roller 54 increases, and the developer stays in the upper part of the nip of the supply roller 54 and the developing roller 53. This tends to increase, which causes a shortage of developer supply to the developing roller 53.

In the stirring chamber 514 of the developing housing 51, the stirring means 55 is arrange | positioned.

The stirring means is arranged in parallel with the replenishing roller, the rotating shaft 551 is freely rotatably mounted on the front and rear side wall 512 constituting the developing housing 51, and the stirring member 552 fixed to the rotating shaft 551. ) And a stirring sheet member 553 having elasticity attached to the stirring member 552.

The stirring member 552 is formed of synthetic resin, and has a plurality of openings in the longitudinal direction (the direction perpendicular to the ground in Fig. 2).

The stirring sheet member 553 is formed of flexible elasticity, for example, polyethylene terephthalate (PETP) resin, and is fixed to the front edge of the stirring member 552 by an adhesive or the like.

The stirring means 55 comprised in this way is continuously rotated in the direction shown by the arrow in FIG. 2 by the drive means not shown.

The developer regulating means 56 includes a braid 561 having flexible elasticity in compression contact with the circumferential surface of the roller 532 constituting the developing roller 53.

The braid 561 is made of, for example, a stainless steel sheet or a spring steel sheet having a thickness of about 0.1 to 0.2 mm, and has a lengthwise dimension substantially the same as the length of the roller 532 constituting the developing roller 53. have.

The braid 561 is attached to the braid attachment portion 51la provided at the photosensitive unit 40 side open terminal of the bottom wall 51l of which the basic terminal thereof constitutes the developing housing 51.

That is, the basic terminal portion of the braid 561 is fitted by the braid attachment portion 511a and the pressing plate 562 and is fixed by the screw 563.

The tip portion of the braid 561 is bent, and the bent portion is configured to be in compression contact with the circumferential surface of the roller 532 constituting the developing roller 53 in the developer regulating region 534.

The housing 51 is equipped with a lid 57 covering the open top.

The lid 57 is made of synthetic resin and is fixed to the top surface of the front side wall and the rear side wall 512 and the left side wall 513 and the connecting member 517 by an adhesive.

On the inner surface of the lid 57, a restricting portion 571 which extends in the front-back direction (the direction perpendicular to the ground in FIG. 2) at the position opposite to the supply roller 54 described above and protrudes toward the developing chamber 5l5 is integrated. It is formed.

Further, a predetermined interval is formed between the lower end of the restricting portion 571 and the outer wind circumferential surface of the roller 542 constituting the above-mentioned supply roller 54.

In the illustrated embodiment, the sheet-like sealing member 58 is attached to the connecting member 517 constituting the developing housing 51.

The sheet-like sealing member 58 is formed of a sheet member having flexible elasticity, such as polyethylene terephthalate (PETP) resin, for example, and is approximately equal to the axial length of the roller 532 constituting the developing roller 53. Have the same length

One end of the sheet-like sealing member 58 is fixed to the connecting member 517 by fixing means such as an adhesive, and the other end thereof is curved to the circumferential surface of the roller 532 constituting the developing roller 53. It is in elastic contact.

The sheet-like sealing member 58 configured as described above, together with the braid 561 of the developer regulating means 56, prevents the developer from scattering from the photosensitive unit 40 side opening of the developing housing 51. .

The process unit 4 comprised as mentioned above is attached so that attachment and detachment may be carried out to the gas housing 20 of the printer 2, as shown in FIG.

That is, the housing main body 21 constituting the gas housing 20 by turning the cover 23 constituting the gas housing 20 of the printer 2 around the shaft 22 in a counterclockwise direction in FIG. 1. ) Is open at the top.

Subsequently, the process unit 4 is mounted upward in the housing main body 21.

In addition, in the housing main body 21, positioning means (not shown) which can mount the photosensitive member 40 of the process unit 4 in a predetermined position is provided.

After attaching the process unit 4 to the housing main body 21 of the gas housing 20, the cover 23 is rotated clockwise around the shaft 22 in the clockwise direction in FIG.

As shown in FIG. 1, the laser apparatus 24 is arrange | positioned under the housing main body 21 which comprises the gas housing 20 of the printer 2. As shown in FIG.

The laser device 24 supplies a laser beam corresponding to printing data from a word processor, for example, to the printer 2 in the electrostatic latent image forming region 423 of the process unit 4. Irradiate the photosensitive layer to form an electrostatic latent image.

In the housing main body 21 constituting the gas housing 20 of the printer 2, a fixing roller 25 is arranged on a downstream shaft of the post transfer guide plate 46, and on the downstream side of the fixing roller 25, The discharge roller 26 is arrange | positioned.

Again, a paper discharge plate 27 is disposed downstream of the discharge roller 26.

In the cover 23 constituting the gas housing 20 of the printer 2, a paper feed plate 28 for placing a transfer sheet on the upper left side in FIG. 2 is disposed.

A paper feed roller 29 is disposed downstream of the paper feed plate 28, and the paper feed roller 29 is rotationally driven in the direction indicated by the arrow in Fig. 2 by driving means (not shown).

The friction pad 30 for separating the paper is disposed opposite the paper feed roller 29.

In the transfer area 422 described above, a non-contact transfer roller 31 is disposed to face the photosensitive drum 42.

The transfer roller 31 is made of conductive foam urethane, and the rotation is freely supported by the cover 23.

The transfer roller 31 has a collar, each of which is not shown, made of an insulating material such as a synthetic resin having an outer diameter greater than that of the transfer roller 31 at both ends thereof, and is provided with collars, and the collar contacts the circumferential surface of the photosensitive drum 42. As a result, the transfer roller 31 slides along with the rotation of the photosensitive drum 42 and operates accordingly.

The distance between the circumferential surface of the transfer roller 31 and the circumferential surface of the photosensitive drum 42 is 0.5.

mm is set.

A constant current of, for example, 10 μA is applied to the transfer roller 31 configured as described above. In the cover 23, an upper guide plate 452 constituting the other side of the transfer plate 45 is arranged.

The printer 2 in the illustrated embodiment is configured as described above, and the operation thereof will be described next.

Each member starts to operate based on a printing command from a word processor or the like not shown, and the surface photosensitive layer of the photosensitive drum 42 is substantially uniformly charged with specific polarity by the charging corona discharger 43. .

Next, a laser beam corresponding to printing data from the word processor or the like is irradiated to the surface of the photosensitive layer of the charged photosensitive drum 42 to the laser device 24 to form an electrostatic latent image.

In this way, the electrostatic latent image formed on the photosensitive layer of the photosensitive drum 42 is developed into a toner image by the developing action by the developing unit 50.

In addition, the developing operation of the developing unit 50 will be described later in detail.

On the other hand, the transfer paper mounted on the paper feed plate 28 is supplied one by one by the action of the paper feed roller 29 and the friction pad 30.

The transfer sheet is guided by the pre-transfer guide plate 45 to be 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 sheet on which the toner image is transferred is guided to the guide plate 46 after transfer and is conveyed to the fixing roller 25.

The transfer paper on which the toner image is heat-fixed by the fixing roller 25 is discharged onto the paper discharge tray 27 by the discharge roller 26.

On the other hand, the circumferential surface of the photosensitive drum 42 that has passed through the transfer area 425 has foreign matter such as paper powder attached to the circumferential surface when the foreign matter recovery brush 44 passes through the foreign matter recovery brush 44. Is removed by

At this time, a part of the residual toner adhering to the circumferential surface of the photosensitive drum 42 together with the foreign matter such as paper powder is also removed.

The residual toner foreign matter recovery brush 44 which has been removed is reliably caught, and may fall.

If the toner in the drop is deposited on the grid member 431 of the corona discharger 43 described above, it causes charge unevenness. However, in the illustrated embodiment, the toner intrusion preventing walls 47 and 470 cause the drop toner to fall. Intrusion into the grid member 431 side is prevented. Further, the residual toner adhering to the circumferential surface of the photosensitive drum 42 passing through the foreign matter recovery brush 44 is recovered by the developing roller 53.

Next, the developing operation of the developing unit 50 will be described.

By starting operation of the developing unit 50, the developing roller 53, the replenishing roller 54, and the stirring means 55 are driven to rotate in the directions indicated by the arrows, respectively, by driving means (not shown).

The developer accommodated in the stirring chamber 514 while the stirring member 552 and the stirring sheet member 553 constituting the stirring means rotates in the direction indicated by the arrow, and stirs over the partition wall 516 while being supplied to the supply roller 54. Is supplied into the developing chamber 515 from above. In addition, at this time, the restriction part 571 formed in the inner surface of the lid 57 is restrict | limited so that the quantity of the developer supplied in the developing chamber 515 may not become excessive.

As described above, the developer supplied by the stirring means 55 rides on the roller 542 of the supply roller 54 and is a nip which is a developer holding area 533 with the roller 532 of the developing roller 53. Is returned to the unit.

Further, 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 the nip as described above, the developing roller 53 from the supply roller 54 is developed. Supply of the developer to the substrate) can be sufficiently performed to prevent the developer shortage.

Further, since the supply roller 54 and the developing roller 53 rotate in the same direction in the developer holding region 533 serving as the nip as described above, it 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 of the supply roller 54 and the developing roller 53 is held on the circumferential surface of the roller 532 constituting the developing roller 53 It is conveyed toward the developer restriction area 534.

At this time, since 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 as described above, the developer rotates the developing roller through both nip portions. It is held at 53 and conveyed to the developer regulating region 534 and the developing region 535, so that when passing through the nip, they are mutually rubbed and sufficiently charged, thus preventing the occurrence of so-called blurring.

In the developer regulating region 534, the braid 561 of the developer regulating means 56 acts on the developer held on the circumferential surface of the roller 532 of the developing roller 53 to act as a circumference of the roller 532. The developer retained on the surface is regulated to the required amount to form a thin layer.

Further, in the developer regulating region 534, the developer regulated by the braid 561 of the developer regulating means 56, and the developer scratched on the bottom wall 511 of the developing housing 51, the supply roller 54 Is rotated in the direction indicated by the arrow, and thus it is conveyed along the guide surface 516b of the partition wall 516 without remaining.

The developing roller 53 is also recovered in the developing region 424.

As described above, the braid of the developer regulating means 56 in the developer regulating region 534 is held on the circumferential surface of the roller 532 constituting the developing roller 53 in the developer holding region 533. The developer formed in the thin layer by the action of 561 is conveyed to the developing region 424 with the rotation in the arrow direction.

In the developing area 424, a developer is applied to an electrostatic latent image on the electrostatic photosensitive member disposed on the circumferential surface of the photosensitive drum 42, so that the electrostatic latent image is developed into a toner image.

For example, the electrostatic latent image has a non-image area charged at about +600 V and an image area charged at about +20 V, and toner as a developer is attached to the image area (so-called reverse phenomenon).

The photosensitive drum 42 and the developing roller 53 are rotationally driven in the direction indicated by the arrow in FIG. 2, and thus, the developing roller 53 constitutes the circumferential surface of the photosensitive drum 42 and the developing roller 53. Like the circumferential surface of the roller 532, it moves in the same direction from the bottom to the top.

1.2 V 1 ≤ V 2 ≤ the circumferential speed V 2 of the roller 532 and the circumferential speed V 1 of the photosensitive drum 42.

Since it is set to 2.5V1, sufficient developer is conveyed to the developing area 424 by the roller 532 of the shape roller 53, and at the same time, friction action of the circumferential surface of the roller 532 against the circumferential surface of the photosensitive drum 42 is carried out. By this means, the developer once adhered to the non-image portion of the electrostatic latent image is appropriately peeled off, thereby obtaining a good toner image having an appropriate development concentration ratio and no blur.

On the other hand, the spent developer, which is held on the circumferential surface of the roller 532 constituting the developing roller 53 and passes through the developing zone 424, is supplied from the nip between the developing roller 53 and the supply roller 54. It is conveyed to the surface of the roller 54.

Further, since the circumferential speed of the supply roller 54 is set to be larger than the circumferential speed of the developing roller, the non-transfer developer attached to the developing roller 53 when passing through the developing region 424 to move the developer in the nip. It is possible to recover the adhesion by weakening the adhesion force, thereby preventing the occurrence of so-called ghost caused by the non-transfer developer adhering to the developing roller 53.

As mentioned above, although this invention was demonstrated based on embodiment applied to the printer, this invention is not limited to embodiment shown, For example, it can be applied to an electrostatic copying machine, and the deviation of the technical thought of this invention is not carried out. Various variations or modifications can be made without modification.

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

That is, according to the present invention, a foreign material recovery brush is disposed between the charging region and the transfer region defined below the photosensitive drum, and the foreign matter recovery brush is placed in contact with the circumferential surface of the photosensitive drum. An image forming apparatus or a process unit of an image forming apparatus having a foreign matter recovery brush arranged in contact with a circumferential surface, the toner intrusion preventing wall having an upper end approaching the circumferential surface of the photosensitive drum between the charger and the foreign matter recovery brush provided. Therefore, even if the residual toner removed together with the foreign matter such as the paper powder by the foreign matter recovery brush is not reliably adhered to the foreign matter recovery brush, the toner intrusion prevention wall prevents the falling toner from entering the charger side.

Therefore, it is possible to prevent occurrence of irrationality such as charging irregularity caused by deposition of toner on the upper surface of the charger.

Further, according to the present invention, the above-described toner penetration preventing wall is formed by the film member, and is attached to the grid member constituting the charger or the grid holding member holding the grid member, so that the interval between the circumferential surface of the photosensitive drum and the circumferential surface is managed. Becomes easy.

Claims (6)

Rotation is freely disposed and disposed in the photosensitive drum 42 and the charging region 422 sequentially passing through the charging region 422, the electrostatic latent image forming region 423, the developing region 424 and the transfer region 425 A charger 43 that charges the circumferential surface of the photosensitive drum 42 to a specific polarity, and an electrostatic force formed in the developing region 424 and formed on the circumferential surface of the photosensitive drum 42 in the electrostatic latent image forming region 423. And a developing device 50 for developing a latent image into a toner image, and transfer means for transferring a toner image formed in the transfer area 424 on the circumferential surface of the photosensitive drum 42 onto a transfer paper, and a charging area 422. The image forming machine which is provided under this photosensitive drum 42, and arrange | positions the foreign material collection brush 44 which contacts the circumferential surface of the photosensitive drum 42 between the charging area 422 and the transfer area 425. In the charging area 422, the charge between the charger 43 and the foreign matter recovery brush 44 An image forming machine comprising: a toner penetration preventing wall (47) (470), the upper end of which is disposed close to the circumferential surface of the photosensitive drum (42). The grid member 431 according to claim 1, wherein the toner penetration preventing members (47) (470) are formed by a film member and are attached to the grid holding member (432) constituting the charger (43). And an image forming machine. 2. The grid holding member according to claim 1, wherein the toner penetration preventing members (47, 470) are formed by a film member, and the grid holding member (50) is mounted to enable attachment and detachment of the grid member (431) constituting the charger (43). And an image forming machine (432). On the photosensitive drum 42 and the lower side of the photosensitive drum 42, rotation is freely arranged and sequentially passes through the charging region 422, the electrostatic latent image forming region 423, the developing region 424, and the transfer region 425. A charger 43 arranged in the prescribed charging region 422 to charge the circumferential surface of the photosensitive drum 42 with a specific polarity, and a photosensitive drum disposed in the developing region 424 and in the electrostatic latent image forming region 423. A developing apparatus 50 for developing the electrostatic latent image formed on the circumferential surface of the 42 to toner image, and disposed between the charging region 422 and the transfer region 425 and contacting the circumferential surface of the photosensitive drum 42. In the processor unit of the image forming unit in which the foreign matter recovery brush 44 is unitized, the circumference of the photosensitive drum 42 between the charger 43 disposed in the charging region 422 and the foreign matter recovery brush 44 Toner intrusion preventing walls (47, 470) are arranged to approach the top of the surface, characterized in that Is a process unit of the image forming machine. 5. The grid member 431 according to claim 4, wherein the toner penetration preventing members (47, 470) are formed by a film member and are attached to the grid holding member (432) constituting the charger (43). And an image forming machine. 5. The grid holding member 432 according to claim 4, wherein the toner penetration preventing members (47, 470) are formed by a film member and are mounted to enable the attachment and detachment of the grid member (431) constituting the charger (43). And an image forming machine.