JPH09319212A - Electrostatic latent image developing device for image forming machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing device capable of preventing the photoreceptive layer of a photoreceptor drum from being damaged by shavings produced by friction between a developing roller and a developer regulating means while preventing the functional defect of a developer regulating means. SOLUTION: This device is equipped with the developing roller 53 disposed in a developing housing and giving developer to an electrostatic latent image formed on the photoreceptor drum 42 in a developing area, a replenishing roller 54 supplying the developer to the peripheral surface of the roller 53 in a developer holding area, and a developer regulating means 56 regulating the quantity of the developer held on the peripheral surface of the roller 53 in a developer regulating area. In such a case, the roller 53 is driven and rotated from a lower side to an upper side in the developing area, the rollers 53 and 54 are driven and rotated from the upper side to the lower side in the developer holding area, and the developer regulating means 56 is disposed under the roller 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image developing device for developing an electrostatic latent image into a toner image in an image forming machine such as an electrostatic copying machine or a laser printer.

[0002]

2. Description of the Related Art In an image forming machine, an electrostatic latent image developing device in which an electrostatic latent image formed on a peripheral surface of a photosensitive drum is developed into a toner image by a developer consisting of a one-component toner is widely used. Has been done. This type of electrostatic latent image developing device is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-36277. The electrostatic latent image developing device disclosed in this publication has a developing housing, a developer which is disposed in the developing housing and holds a developer on a peripheral surface in a developer holding area, and the held developer faces a photosensitive drum. A developing roller for carrying the electrostatic latent image by carrying it to a developing area, a replenishing roller for supplying the developer to the peripheral surface of the developing roller in the developer holding area, and the developing roller. And a developer regulating means for regulating the amount of the developer retained on the peripheral surface of the developing roller in a developer regulating region located between the developer retaining region and the developing region. The developing roller is configured to be rotationally driven from the upper side to the lower side in the developing area. Therefore, the developer regulation area is located above the developer holding area, and the developer regulation area is set. Means are disposed above the developing roller.

[0003]

Since the developing roller is generally composed of a synthetic rubber material such as urethane rubber, the peripheral surface of the developing roller is scraped off at the upper portion by the developer regulating means in pressure contact. There is a problem that the shavings are conveyed to the developing area and damage the photosensitive layer of the photosensitive drum. Further, in the case where the developer regulating means is constituted by a rubber blade, there is a problem that the rubber blade is scraped and the scrap is conveyed to the developing area to damage the photosensitive layer of the photosensitive drum.

In order to solve the above problem, the developing roller is rotationally driven from the lower side to the upper side in the developing area so that the developer regulation area is located below the developer holding area. Conceivable. According to this structure, the developer adhered to the peripheral surface of the developing roller in the developer holding area and scraped off in the developer regulating area collects on the bottom wall of the developing housing, and the lower side of the nip between the developing roller and the replenishing roller is retained. If the developer stays in the developer, the developer regulating means will malfunction and it will not be possible to form a uniform thin layer of the developer on the peripheral surface of the developing roller.

The present invention has been made in view of the above facts, and its main technical problem is to prevent the occurrence of malfunction of the developer regulating means, and at the same time, by the friction between the developing roller and the developer regulating means. It is an object of the present invention to provide an electrostatic latent image developing device capable of preventing damage to the photosensitive layer of a photosensitive drum due to shavings generated.

[0006]

In order to achieve the above main technical problems, according to the present invention, a developing housing and a developer holding area disposed in the developing housing for holding a developer on a peripheral surface thereof are provided. A developing roller for conveying the held developer to a developing area facing the photoconductor drum and applying it to an electrostatic latent image, and a developing roller disposed in the developing housing on the peripheral surface of the developing roller in the developer holding area. A replenishing roller for supplying the developer, and a developer regulating means for regulating the amount of the developer retained on the peripheral surface of the developing roller in the developer regulating region located between the developer retaining region and the developing region. In the electrostatic latent image developing device of the image forming machine, the developing roller is rotationally driven from the lower side to the upper side in the developing area, and the developing roller and the replenishing roller are both upper side in the developer holding area. From down An electrostatic latent image developing device for an image forming machine is provided, wherein the developer regulating means is arranged below the developing roller. It

Further, according to the present invention, there is provided an electrostatic latent image developing device for an image forming machine in which the peripheral speed of the supply roller is set to be higher than the peripheral speed of the developing roller.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an electrostatic latent image developing device 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 equipped with an electrostatic latent image developing device constructed according to the present invention.

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

As shown in FIG. 2, the process unit 4 includes a photoconductor unit 40 and a developing unit as an electrostatic latent image developing device which is swingably supported by the photoconductor unit 40 via a support shaft 5. And 50. The photoreceptor unit 40 includes a photoreceptor support means 41. The photoreceptor support means 41 is provided with a pair of side wall members 411 (in FIG. 2, spaced apart in the front-rear direction (direction perpendicular to the paper surface)). (Only the rear side wall member is shown) and a connecting member 412 connecting the lower portions of the pair of side wall members 411. The photoconductor supporting means 41 configured in this way
Are integrally molded of synthetic resin. The support portion 4 having a mounting hole 414 at the upper end portion of the pair of side wall members 411 forming the photosensitive member support means 41 on the developing unit 50 side.
13 are provided respectively. By inserting a support shaft 5 made of a metal bar disposed in a later-described developing housing of the developing unit 50 into a mounting hole 414 provided in the supporting portion 413, the photosensitive unit 40 and the developing unit 50 can be connected to each other. Is swingably supported.

The photoreceptor unit 40 has a photoreceptor drum 42 having a photosensitive layer formed on a peripheral surface. The rotating shaft 421 of the photosensitive drum 42 is rotatably supported by a pair of side wall members 411 constituting 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 developing unit 50 described later. In the developing region, which is a contact portion (nip portion) with a developing roller to be rotated, the developing roller is driven to rotate upward from the lower side. The connecting member 412 of the photoconductor supporting means 41 is provided with a charging corona discharger 43 facing the lower peripheral surface of the photoconductor drum 42. A paper dust removing brush 44 that comes into contact with the peripheral surface of the photoconductor drum 42 is disposed on the upstream side in the rotation direction of the body drum 42.

Between the pair of side wall members 411 constituting the photoconductor supporting means 41, the transfer paper fed obliquely from the upper left in FIG. 2 is directed to the transfer area 422 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. A plurality of guide ribs 451a are integrally formed on the upper surface of the lower guide plate 451 at intervals in the longitudinal direction (the direction perpendicular to the paper surface in FIG. 2). The lower guide plate 451 is also provided with a plurality of reinforcing ribs 45 on the lower surface at intervals in the longitudinal direction (the direction perpendicular to the paper surface in FIG. 2).
1 b is integrally formed, and the reinforcing rib 451 b is configured to abut on the support shaft 5. Therefore,
Even if the lower guide plate 451 is pressed by the upper surface thereof and bends, the reinforcing ribs 451b abut on the support shaft 5 to prevent the lower guide plate 451 from bending. Also, the lower guide plate 451
Is a pair of side wall members 41 constituting the photoconductor supporting means 41.
1 serves as a connecting member for connecting the upper portions to each other, and the rigidity of the photosensitive member supporting means 41 can be improved. Further, in the illustrated embodiment, since the lower guide plate 451 is integrally formed with the pair of side wall members 411, the positional relationship with respect to the photosensitive drum 42 rotatably supported by the pair of side wall members 411 can be determined with high precision. Can be maintained.

A post-transfer guide plate 46 for guiding the transfer paper transferred in the transfer area 422 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 for connecting the pair of side wall members 411 constituting the photoconductor supporting unit 41 to each other, and can improve the rigidity of the photoconductor supporting unit 41.

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

In the developing housing 51, a developing roller 53, a supply roller 54, a stirring means 55 and a developer regulating means 56 are provided. The developing roller 53 is
A rotating shaft 531 provided in the developing chamber 515 of the developing housing 51 and rotatably mounted on the front and rear side walls 512 constituting the developing housing 51, and a solid synthetic rubber roller fixed to the outer peripheral surface of the rotating shaft 531 532. The rotating shaft 531 can be formed from an appropriate metal material such as stainless steel. Solid synthetic rubber roller 53
2 is made of a relatively flexible and conductive material, for example, a conductive solid synthetic rubber such as urethane rubber. In the illustrated embodiment, a solid synthetic rubber roller 5 is used.
The surface roughness of the peripheral surface of 32, that is, the ten-point average roughness Rz specified in JIS B 0601 is set to 5.0 to 12.0. The volume resistance of the solid synthetic rubber roller 532 is set to about 10 ⁴ to 10 ⁹ Ω · cm. The roller hardness of the solid synthetic rubber roller 532 is set to 60 to 80 in Asker C hardness in the illustrated embodiment. The roller 532 of the developing roller 53 configured as described above is exposed through a right opening formed in the developing housing 51, and is exposed to the photosensitive drum 42.
Is positioned opposite to. The peripheral surface of the roller 532 constituting the developing roller 53 is pressed against the peripheral surface of the photosensitive drum 42 in the developing region, and the peripheral surface of the roller 532 is slightly elastically compressed at the pressed nip. ing. Rotating shaft 53 of developing roller 53
1 is driven to rotate from the lower side to the upper side in a direction indicated by an arrow by a driving unit (not shown), that is, in a developing area which is a contact portion between the roller 532 and the photosensitive drum 42. The rotation of the rotation shaft 531 causes the roller 532 to rotate.
Is also rotationally driven in the direction shown 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 535. In the illustrated embodiment, a constant voltage of 300 V is applied to the rotating shaft 531 of the developing roller 53.

The replenishing roller 54 is disposed in the developing chamber 515 of the developing housing 51 in parallel with the developing roller 53, and is rotatably mounted on the front and rear side walls 512 constituting the developing housing 51. Axis 541,
And a roller 542 fixed to the outer peripheral surface of the rotating shaft 541. The rotating shaft 541 can be formed of an appropriate metal material such as stainless steel, similarly to the rotating shaft 531 of the developing roller 53. The roller 542 is made of foam such as foamed silicone or foamed urethane. The roller 542 is a roller 5 of the developing roller 53 in a developer holding region 533 which is a nip portion with the developing roller 53
32. Roller 54 of supply roller 54
The hardness of the foam constituting the developing roller 2 is considerably smaller than the hardness of the roller 532 constituting the developing roller 53 (for example, about 35 in Asker C hardness), and the roller 542 is pressed against the roller 532 of the developing roller 53. It is desirable that the roller 542 be elastically compressed by about 0.1 to 0.6 mm in the nip area. Roller 5
42 also has conductivity, and its volume resistance is 10 ² to 1
It is set to about 0 ⁶ Ω · cm. The rotating shaft 541 of the replenishing roller 54 is 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. Rotary axis 5
Due to the above rotation of the roller 41, the roller 542 is also driven to rotate in the direction shown by the arrow. In the illustrated embodiment,
The rotation shaft 541 of the supply roller 54 has the developing roller 53
A constant voltage of 450 V, which is higher than the applied voltage, is applied.

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

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

The developer regulating means 56 is provided with a flexible elastic blade 561 which is pressed against the peripheral surface of the roller 532 which constitutes the developing roller 53. The blade 561 has, for example, a thickness of 0.1 to 0.2.
The developing roller 53 is formed of a stainless steel plate or a spring steel plate having a length of about mm, and has a longitudinal dimension substantially equal to the length of the roller 532 constituting the developing roller 53. Blade 56
1 is attached to a blade mounting portion 511a provided at a base end of the bottom wall 511 constituting the developing housing 51 at an open end on the photoconductor unit 40 side. That is, the blade 56
1 has a blade mounting portion 511 a and a holding plate 56.
2 and fixed by screws 563. The distal end of the blade 561 is bent, and the bent portion is configured to be pressed against the peripheral surface of the roller 532 constituting the developing roller 53 in the developer regulating region 534.

The developing housing 51 is provided with a lid 57 for covering the opened upper part. The lid 57 is made of a synthetic resin, and is fixed to an upper surface of the front and rear side walls 512, the left side wall 513, and the upper surface of the connecting member 517 constituting the developing housing 51 by an adhesive. A regulating portion 571 that extends in the front-rear direction (a direction perpendicular to the paper surface in FIG. 2) and protrudes toward the developing chamber 515 is integrally formed on the inner surface of the lid 57 at a position facing the supply roller 54. A predetermined interval is provided between the lower end of the regulating portion 571 and the outer peripheral surface of the roller 542 constituting the supply roller 54. In the illustrated embodiment, 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 sheet member having flexibility and elasticity, such as ETP) resin, and has substantially the same length as the axial length of the roller 532 constituting the developing roller 53. One end of the sheet-shaped sealing member 58 is connected to the connecting member 517.
Is fixed to the developing roller 53 by a fixing means such as an adhesive.
2 is elastically brought into contact with the peripheral surface. The sheet-shaped sealing member 58 thus configured is provided together with the blade 561 of the developer regulating means 56 on the developing housing 5.
The developer is prevented from scattering from the opening on the side of the photoconductor unit 40.

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

As shown in FIG. 1, at the bottom of the housing body 21 which constitutes the machine housing 20 of the printer 2,
A laser unit 24 is provided. The laser unit 24 applies laser light corresponding to print data from, for example, a word processor connected to the printer 2 to the photosensitive drum 4 in the exposure area 423 of the process unit 4.
Irradiate the photosensitive layer No. 2 to form an electrostatic latent image. A fixing roller pair 25 is disposed on the downstream side of the post-transfer guide plate 46 on the housing body 21 constituting the body housing 20 of the printer 2, and a discharge roller pair 26 is disposed on the downstream side of the fixing roller pair 25. Are arranged. Further, a discharge tray 27 is provided downstream of the discharge roller pair 26.

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

The printer 2 in the illustrated embodiment is configured as described above, and its operation will be described below. Each of the above members starts to operate based on a print command from a word processor (not shown) or the like, and the charging corona discharger 4
3, the surface photosensitive layer of the photosensitive drum 42 is substantially uniformly charged to a specific polarity. Next, a laser beam corresponding to print data from a word processor or the like is emitted from the laser unit 24 to the charged surface of the photosensitive layer of the photosensitive drum 42, and an electrostatic latent image is formed. The electrostatic latent image thus formed on the photosensitive layer of the photosensitive drum 42 is developed into a toner image by the developing operation of the developing unit 50. The developing operation of the developing unit 50 is described below.
Details will be described later. On the other hand, the transfer paper placed on the paper feed tray 28 is 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.
1 and the toner image formed on the photosensitive drum 42 is transferred onto the surface thereof. The transfer paper on which the toner image has been transferred is guided by the guide plate 46 after the transfer, and is conveyed to the fixing roller pair 25. The transfer paper on which the toner image has been heated and fixed by the fixing roller pair 25 is discharged onto a discharge tray 27 by the discharge roller pair 26.

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 supply roller 54, and the stirring means 5
5 are rotationally driven in directions indicated by arrows by drive means (not shown). Stirring member 55 constituting stirring means 55
2 and the stirring sheet member 553 rotate in the direction indicated by the arrow, the developer accommodated in the stirring chamber 514 passes over the partition wall 516 while being stirred, and
Is supplied into the developing chamber 515 from above. At this time, the regulating portion 571 formed on the inner surface of the lid 57 causes
The amount of the developer supplied into the developing chamber 515 is limited so as not to be excessive. The developer supplied by the agitating unit 55 in this manner rides on the roller 542 of the supply roller 54 and is transported to the nip portion which is the developer holding area 533 with the roller 532 of the developing roller 53. Since the supply roller 54 and the developing roller 53 rotate in the same direction from the upper side to the lower side in the developer holding area 533 which is a nip portion as described above, the supply roller 54 and the developing roller 53
The developer is sufficiently supplied to the developer, and the shortage of the developer can be prevented. Further, the supply roller 54 and the developing roller 5
3 is a developer holding area 533 which is a nip portion as described above.
, The motor can be driven reliably without requiring a large driving force.

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

In the developer 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 retain it on the peripheral surface of the roller 532. The developer is regulated to the required amount to form a thin layer. The developer regulated in the developer regulating area 534 by the blade 561 of the developer regulating means 56 and scraped off on the bottom wall 511 of the developing housing 51 is rotated by the supply roller 54 in the direction shown by the arrow. The partition wall 516 without stopping
Along the guide surface 516b.

As described above, it is held on the peripheral surface of the roller 532 which constitutes 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 developed developer is transferred to the developing area 535 as it rotates in the direction of the arrow.
Transported to In the developing area 535, the 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, an 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 indicated by the arrow in FIG. 2. Therefore, in the developing area 535, the peripheral surface of the photosensitive drum 42 and the roller
Both of them are moved from the lower side to the upper side in the same direction. The peripheral speed V2 of the roller 532 and the photosensitive drum 4
2 is set to 1.2V1 ≦ V2 ≦ 2.5V1, so that a sufficient amount of developer is conveyed to the developing area 535 by the rollers 532 of the developing roller 53, and the peripheral speed of the photosensitive drum 42 is changed. The developer that once adhered to the non-image portion of the electrostatic latent image is appropriately peeled off by the rubbing action of the peripheral surface of the roller 532 against the surface, so that a good toner image having an appropriate development density and no fogging can be obtained. Obtainable. On the other hand, a roller 532 constituting 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 535 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 supply roller 54 is set to be higher than the peripheral speed of the developing roller 53, the developer is moved in the nip portion. The adhesive force of the transfer developer can be weakened and collected, so that a so-called ghost caused by the non-transfer developer adhered to the developing roller 53 can be prevented.

Although the electrostatic latent image developing device according to 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 is applied to, for example, an electrostatic copying machine. It is also possible to make various changes or modifications without departing from the scope of the technical idea of the present invention.

[0030]

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

That is, according to the present invention, the developing roller is rotationally driven from the lower side to the upper side in the developing area, and the developing roller and the replenishing roller are both rotationally driven from the upper side to the lower side in the developer holding area. Since the developer regulating means is disposed below the developing roller, the developing roller scraped by the friction between the developing roller and the developer regulating means or the scrap of the developer regulating means. Immediately falls and is not conveyed to the developing area located above the developer regulating means. Therefore, it is possible to prevent the photoconductor from being damaged by the scraped off slag, and to prevent the generation of black spots in the transferred image due to the slag. As described above, when the developing roller is rotationally driven from the upper side to the lower side in the developer holding area and the developer regulating means is arranged below the developing roller, the development regulated by the developer regulating means is scraped off. The developer tries to collect on the bottom wall of the developing housing, but the supply roller is driven to rotate from the upper side to the lower side in the developer holding area, so the scraped developer does not remain and the supply roller rotates. Accordingly, the developer is conveyed along the bottom wall of the developing housing, so that the developer does not stay below the nip between the developing roller and the replenishing roller. Therefore, it is possible to prevent occurrence of malfunction of the developer regulating means due to the developer staying below the nip between the developing roller and the replenishing roller.

Further, according to the present invention, since the developing roller and the replenishing roller both rotate in the same direction from the upper side to the lower side in the developer holding area which is the nip portion as described above, the replenishing roller to the developing roller moves. The developer is supplied sufficiently,
It is possible to prevent the developer shortage. Further, according to the present invention, since the developing roller and the replenishing roller both rotate in the same direction from the upper side to the lower side in the developer holding area which is the nip portion as described above, the developer passes through both the nip portions. Since the toner is held by the developing roller and conveyed to the developer regulating area and the developing area, they are rubbed against each other and sufficiently charged when passing through the nip portion, so that the occurrence of so-called fog is prevented. Further, since the developing roller and the replenishing roller both rotate in the same direction in the developer holding area, which is the nip portion, as described above, they can be reliably driven without requiring a large driving force.

Further, in the present invention, since the peripheral speed of the replenishing roller is set to be higher than the peripheral speed of the developing roller, the developer passes through the developing area in order to move the developer in the nip portion which is the developer holding area. At this time, the adhesive force of the non-transfer developer attached to the developing roller can be weakened and recovered, and so-called ghost caused by the non-transfer developer attached to the developing roller can be prevented. .

[Brief description of drawings]

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

2 is a sectional view of a process unit including the electrostatic latent image developing device of FIG.

[Explanation of symbols]

 2: printer 4: process unit 5: support shaft 20: body housing 21: housing body 23: cover 24: laser unit 25: fixing roller pair 26: discharge roller pair 27: discharge tray 28: paper feed tray 29: paper feed Roller 30: Friction pad 31: Transfer roller 40: Photoconductor unit 41: Photoconductor support means 42: Photoconductor drum 43: Corona discharger for charging 44: Paper dust removal brush 45: Guide plate pair before transfer 46: Guide after transfer Plate 50: developing unit 51: developing housing 52: coil spring 53: developing roller 54: replenishing roller 55: stirring means 56: developer regulating means 57: lid 58: sheet-shaped seal member 411: side wall member of photosensitive member supporting means 412 : Connecting member of photoconductor supporting means 422: Transfer area 423: Exposure area 514: Stirring chamber 515: Development chamber 17: connecting the developer housing member 533: the developer holding zone 534: the developer regulating zone 535: blade of the developer regulating means: the developing zone 561

Front Page Continuation (72) Inventor Yukiko Terada 1-22-28 Tamazo, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Hiromitsu Ogawa 1-2-28 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Incorporated (72) Inventor Masahiro Masaki Exhibition 1-22 Tamatsukuri Chuo-ku, Osaka Mita Industrial Co., Ltd.

Claims (2)

[Claims] 1. A developing housing, and a developer holding area disposed in the developing housing, which holds a developer on a peripheral surface thereof and conveys the held developer to a developing area facing a photosensitive drum to electrostatically discharge the developer. A developing roller for applying the latent image, a replenishing roller arranged in the developing housing for supplying the developer to the peripheral surface of the developing roller in the developer holding area, the developer holding area and the developing area. In an electrostatic latent image developing device of an image forming machine, comprising: a developer regulating means for regulating the amount of developer retained on the peripheral surface of the developing roller in a developer regulating area located between the developing roller and the developing roller. The developing roller is rotationally driven from the lower side to the upper side, and the developing roller and the replenishing roller are both rotationally driven from the upper side to the lower side in the developer holding area. The regulatory measures are Is disposed on the lower side of the developing roller, an electrostatic latent image developing device of an image forming machine, characterized in that. 2. The electrostatic latent image developing device of an image forming machine according to claim 1, wherein the peripheral speed of the supply roller is set to be higher than the peripheral speed of the developing roller.