JP3263564B2 - Contact type charger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type charger for charging a photosensitive member in an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, a charger, an exposure device, a developing device, a transfer device, a cleaning unit, and a static eliminator are arranged on the outer periphery of a photoreceptor, and the outer periphery of the photoreceptor is charged in the process of rotating the photoreceptor. Irradiates the charged portion of the photoreceptor with light corresponding to a print signal from an exposure device to form an electrostatic latent image, and develops the electrostatic latent image on the photoreceptor with a developing device. The image is transferred to paper by a transfer device, the transferred image on the paper is fixed by a fixing device, and the toner remaining on the outer periphery of the photoconductor is wiped by a cleaning unit for the next image formation, and the charge of the photoconductor is removed. 2. Description of the Related Art There is an electrophotographic apparatus in which static elimination is performed by a static eliminator.

[0003] There are a non-contact type and a contact type as a charger used in such an electrophotographic apparatus. Non-contact type chargers require ozone countermeasures because ozone is generated by corona discharge. In recent years, there has been a strong demand for reduction in size and weight and cost reduction for personal use.

Here, an example of a conventional contact type charger is shown in FIG.
Shown in As shown in FIG. 1A, the contact type charger 100 includes a support member 102 formed of a conductive and flexible material and connected to a power supply.
When the photosensitive member 103 is mounted on the main body to which the support member 102 is attached, the charging sheet 101 is elastically bent and the reaction force of the photosensitive sheet 10
3.

[0005]

However, if the photosensitive member 103 is inadvertently mounted, the charging sheet 101 has a resistance to the rotation of the photosensitive member 103 (right side) as shown in FIG. 7B. When the photosensitive member 103 rotates in the direction of the arrow (clockwise) as shown in FIG. 3C, the leading end of the charging sheet 101 is raised to the opposite side by friction with the photosensitive member 103. In the so-called against contact state, the photosensitive member 103
To the photosensitive member 103 depending on the position of the charging sheet 101 in the longitudinal direction. This has an effect on the uniformity of the electric charges charged on the outer periphery of the photoconductor 103, and causes a problem of image quality deterioration.

[0006]

According to the first aspect of the present invention,
A charging sheet formed of a conductive and flexible material and connected to a power source; and a support for supporting the charging sheet.
A support, and the support presses the charged sheet at an angle to extend from the outer periphery of the photoconductor toward the rotation direction advancing side of the photoconductor from the rotation center of the photoconductor, and is a contact type charger tip further said photosensitive body electrophotographic apparatus the charge sheet to be flexed in the direction of rotation advancing side you supported while for pressing the outer peripheral surface of the photosensitive member. According to a second aspect of the present invention, in the contact-type charger according to the first aspect, the charging sheet is pushed by a bent portion formed by a bent end portion of a thin piece of the support. Bent.

[0007]

In the assembling process, the photoconductor and the charged sheet relatively approach each other. During this approach, the photosensitive sheet is exposed at a position where the leading end of the charged sheet is closer to the photoconductor in the rotational direction than the rotation center of the photoconductor. When the support and the photoreceptor are assembled at a fixed position, the charged sheet is bent further toward the rotational direction of the photoreceptor by contact with the photoreceptor, and the reaction force is generated by the reaction force. Resiliently contacts the photoreceptor.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. First, the overall structure of the electrophotographic apparatus is shown in FIG. 1 is a main body of the electrophotographic apparatus. In the center of the main body 1 is a CGL layer and a CT on an aluminum tube having an outer shape of 16 mm.
A photoreceptor 2 having an L layer formed thereon is rotatably provided, and an exposure device 3 for forming an electrostatic latent image on the photoreceptor 2 is provided below the main body 1.
Is provided. The exposure device 3 deflects laser light emitted from a laser diode (not shown) and having a frequency of 780 nm by a polygon mirror 5 driven by a polygon motor 4, and deflects the deflected light through an fθ lens 6 to a mirror 7. 8, the light is reflected on the photoreceptor 2 through an fθ lens 9 and a dustproof glass 10.

The main unit 1 includes a process unit 1.
1 and a fixing device 12 are mounted. The process unit 11 includes a case 1 in which the photoconductor 2 is rotatably held.
3, a contact type charger 14 for charging the outer peripheral surface of the photoreceptor 2 to form an image, a developing unit 15 for developing an electrostatic latent image on the photoreceptor 2, and cleaning the outer peripheral surface of the photoreceptor 2 The cleaning unit 16 is mounted.

Here, the structure of the process unit 11 will be described in detail with reference to FIG. The developing device 15 includes:
The case 13 has a toner container 17 formed integrally therewith. The toner container 17 includes a developing roller 18.
A toner supply roller 19 for uniformly supplying toner to the outer periphery of the developing roller 18 and a toner supply paddle 20 for stirring non-magnetic one-component toner in the toner container 17 are rotatably supported. A toner layer forming blade 21 having a silicon chip 21a at its tip, which contacts the developing roller 18, is provided. The developing roller 1
No. 8 has an outer shape defined as 16 mm and a hardness of 70 ° (AS
KER-C), made of a conductive elastic material (urethane elastomer) having a specific resistance of 1 × 10 ⁷ Ω · cm, and
A voltage of 0 V is applied.

The cleaning unit 16 includes a waste toner container 22 formed integrally with the case 13, a plate-like support member 23 fixed to the waste toner container 22,
A cleaning blade 24 fixed to the support member 23 to wipe off residual toner adhering to the outer periphery of the photoreceptor 2
And The cleaning blade 24 is formed of a urethane elastomer having a hardness of about 65 ° (JIS-A), and has a free length of 8 mm and a thickness of 1.8 mm.

As shown in FIG. 4, the fixing device 12 includes a heating roller 2 and a case 25 attached to the main body 1.
6, the pressure roller 27, and a pair of paper discharge rollers 28 are rotatably mounted.

Further, a paper feed tray 29 is detachably mounted on the upper part of the main body 1. A paper feed roller 31 for pulling out the paper 30 inserted from the paper feed tray 29 is rotatably provided at an upper part of the main body 1, and below the paper feed roller 31 is urged by a spring 32 to support a spindle. 3
A paper pressing plate 34 is provided to prevent double feeding of the paper 30 by rotating about the fulcrum 3 and contacting the paper feed roller 31. Furthermore, a cover 35 for opening and closing the upper surface of the main body 1
Are provided rotatably on the axis of the paper feed roller 31. The cover 35 has a pair of transport rollers 36 and a transfer roller 3 elastically contacting the photosensitive member 2.
7 are rotatably held. This transfer roller 37
Has an outer shape of 12 mm and a hardness of 30 ° (ASK
ER-C), formed of a urethane foam material having a specific resistance of 1 × 10 ⁸ Ω · cm and an average cell diameter of about 150 μm.
A voltage of 0 kV is applied.

Here, the structure of the contact type charger 14 will be described with reference to FIGS. This contact type charger 1
Reference numeral 4 includes a charging sheet 38 formed of a conductive and flexible material, and a support 39 that supports the charging sheet 38. As shown in FIG. 2A, the support 39 in this embodiment has a thin piece 41 made of polyethylene terephthalate to which a double-sided adhesive tape 40 is adhered to the inner surface. A bent portion 42 is formed at the tip of the thin piece 41 so as to be bent in the shape of "". In the state where the thin piece 41 is adhered to the back of the support 39 and the back of the charging sheet 38, FIG.
As shown in (b), the charging sheet 38 is bent by the bent portion 42 of the thin piece 41, and the angle between the upper portion of the charging sheet 38 and the upper surface of the support 39 is determined as α. The angle α is an angle at which the charging sheet 38 extends from the outer periphery of the photosensitive member 2 toward the rotation direction advancing side of the photosensitive member 2 with respect to the rotation center 2a of the photosensitive member 2 (see FIG. 1B). It is. Although not shown, a guide portion for positioning the support 39 is formed in the case 13 of the process unit 11. The case 1 is provided at both ends of the support 39.
3 are formed with screw holes 43 into which mounting screws (not shown) inserted from both side ends are screwed.

The charging sheet 38 is formed of a urethane foam material as a base material containing carbon or the like. The hardness of this material is 30 ° (ASKER-
C), the specific resistance is 5 × 10 ⁷ Ω · cm, and the average bubble diameter is about 4
0 μm. Further, the thickness of the charging sheet 38 is 1 mm,
The free length is set to 7 mm. And the support 39
Is made of a zinc-plated metal material. Such a contact type charger 14 has a DC component of -780 V,
The AC component has a voltage of 600 V (peak-to-peak voltage).
9, the photosensitive member 2 is uniformly charged to -530 V via the charging sheet 38.

In such a configuration, when assembling the process unit 11, the contact type charger 14 is connected to the case 1.
3 and is fixed by screwing mounting screws inserted from both side ends of the case 13 into the screw holes 43. Subsequently, the photoconductor 2 is assembled in the case 13. In this case, the angle formed between the upper portion of the charging sheet 38 and the upper surface of the support 39 is defined as α, and the angle α is determined by moving the charging sheet 38 from the outer periphery of the photoconductor 2 to the rotation center 2 a ( 1 (b), the angle of the photosensitive member 2 extends toward the rotation direction advancing side.
When the photosensitive member 2 approaches the contact type charger 14 from the state shown in FIG. 3A, the photosensitive sheet 2 is exposed at a position where the leading end of the charging sheet 38 is closer to the rotation direction advance side of the photosensitive member 2 than the rotation center of the photosensitive member 2. As shown in FIG. 1B, when the support 39 and the photoconductor 2 are supported at fixed positions, the charging sheet 38 is further exposed to light by contact with the photoconductor 2. Body 2
And is elastically pressed against the photoreceptor 2 in a so-called abutting state. At this time, the support 39
Is between the upper surface of the charging sheet 38 and the upper surface of the charging sheet 38 is α
Smaller than. The difference between α and β is the biting depth (2.5 mm or more) of the charging sheet 38 into the photoconductor 2.

Accordingly, as shown in FIG. 1B, even if the photosensitive member 2 rotates in the direction of the arrow, the leading end of the charging sheet 38 does not occur in the direction opposite to the rotating direction of the photosensitive member 2.
The charging sheet 38 can be brought into uniform contact with the outer periphery of the photoconductor 2. Thereby, the photoconductor 2 is uniformly charged,
The charged portion is irradiated with light from the exposure device 3 to form an electrostatic latent image. When the portion where the electrostatic latent image is formed reaches the outer periphery of the developing roller 18, the one-component toner is frictionally charged due to friction between particles of the one-component toner and friction between the toner layer forming blade 21 and the developing roller 18. The component toner is attracted to the electrostatic latent image, where the electrostatic latent image is developed as a toner image. The toner image on the photoconductor 2 is transferred by the transfer roller 37 onto the sheet 30 fed by the feed roller 31 and transported by the transport roller 36. The transferred image on the sheet 30 that has passed through the transfer roller 37 is
The sheet 30 is heated by the pressure roller 6 and is pressed and fixed by the pressure roller 27, and the sheet 30 after the fixing is discharged by the discharge roller 28.

Thereafter, the toner remaining on the photosensitive member 2 is wiped off by the cleaning blade 24 to form the next image. In this case, even if the toner that cannot be completely wiped out remains, the charging sheet 38 of the contact type charger 14 is pressed in with a biting depth of 2.5 mm or more in the state of contact with the whiz, so the charging sheet 38 remains. The outer periphery of the photoconductor 2 is charged evenly while removing the toner.

The cleaning blade 24 approaches the upstream side of the charging sheet 38, and the optical path through which the laser beam passes approaches the downstream side.
As a result, the charging sheet 38 is tilted in a desired direction, so that the support 39 can be mounted in a straight posture without tilting. Thereby, as shown in FIG. 1B, the width L of the contact type charger 14 can be reduced, and accordingly, the optical path of the contact type charger 14, the cleaning blade 24, and the laser beam are narrowed. it is possible to contribute to miniaturization of the entire electrophotographic apparatus was arranged in the space.

[0020]

[0021]

[0022]

The present invention relates to a support for supporting a charged sheet.
Wherein the support is bent at an angle at which the charged sheet extends from the outer periphery of the photoconductor toward the rotation direction advancing side of the photoconductor from the center of rotation of the photoconductor, and the leading end of the charged sheet is bent. since There it supports the charge sheet as further flexed in the rotational direction advancing side of the photosensitive member in a state to be pressed against the outer peripheral surface of the photosensitive member, assembling a support for supporting the charging sheet and the photoreceptor In the process, the leading end of the charged sheet can be made to interfere with the outer periphery of the photoconductor at a position closer to the rotation direction advance side of the photoconductor than the rotation center of the photoconductor,
Therefore, in a state where the support and the photoconductor are supported at a fixed position, the charged sheet can be further bent toward the rotation direction advance side of the photoconductor by contact with the photoconductor to make elastic contact with the photoconductor. it can. Therefore, the charging sheet can be pressed against the photoconductor in a state in which the charging sheet is bent in a forward direction that does not oppose the rotation direction of the photoconductor, so that the outer circumference of the photoconductor can be uniformly charged.

[Brief description of the drawings]

FIGS. 1A and 1B show the relationship between a photoconductor and a contact-type charger in one embodiment of the present invention, wherein FIG. 1A is a side view showing a process of assembling the photoconductor, and FIG. It is a side view which shows the relationship between a photoreceptor and a contact type charger.

FIG. 2 shows an assembly structure of a contact type charger.
(A) is a side view which shows an assembly process, (b) is a side view which shows an assembly completion state.

FIG. 3 is a perspective view showing a contact charger.

FIG. 4 is a vertical sectional side view showing the structure of the electrophotographic apparatus.

FIG. 5 is a vertical sectional side view showing a structure of a process unit.

FIG. 6 shows a conventional example, in which (a) shows a contact type charger;
Side view, (b) photoconductor and contact band during assembly
The side view which shows the relationship with an electric appliance, (c) is a feeling at the time of driving.
It is a side view which shows the relationship between an optical body and a contact-type charger.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhisa Takeda 570, Ohito, Oni-cho, Tagata-gun, Shizuoka Prefecture Inside Tech Onito Plant (56) References JP-A-8-62941 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 15/02

Claims (2)

(57) [Claims] 1. A charge sheet formed of a conductive and flexible material and connected to a power supply, and a support for supporting the charge sheet , wherein the support is
An angle at which the sheet extends from the outer periphery of the photoconductor toward the rotation direction advancing side of the photoconductor from the rotation center of the photoconductor
Press bending, benzalkonium be supported in a state for pressing the charge sheet to the outer circumferential surface of the front <br/> Symbol photoreceptor so that the tip of the charge sheet is further flexed in the rotational direction advancing side of the photosensitive member and the A contact-type charger. 2. The charging sheet according to claim 1, wherein the charging sheet is pressed and bent by a bent portion formed by a front end portion of the flakes of the support, which is bent in a V shape. Contact type charger.