JPH07295351A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate need for specially providing an image forming device with an electrostatic charger, a developing roller and the like, to miniaturize the whole of the device and to reduce the manufacturing cost thereof. CONSTITUTION:When a photoreceptive drum 12 is rotated in a direction shown by the arrow, the surface thereof is electrostatically charged to have, positive polarity by a bias voltage impressed on the electrical; conductive part 26a of an elastic blade 26. Besides, toner 24 is triboelectrifically charged to have the negative polarity by the insulating part 26b of the blade 26. Moreover, toner thin layer 36 is formed on the surface of the drum 12 by the blade 26. When the photoconductive layer 12c of the drum 12 is exposed by an LED head array 34, an electrostatic latent image is formed at the exposed part and the toner 24 on the electrostatic latent image is transferred on a recording material 38 by a transfer roller 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus,
In particular, the present invention relates to an image forming apparatus applied to a printer, a copying machine, a facsimile, or the like.

[0002]

2. Description of the Related Art A conventional image forming apparatus 1 shown in FIG. 6 includes a photosensitive drum 2 which is rotated by a motor (not shown). A discharge lamp 3, a charger 4 and an exposure lamp are provided around the photosensitive drum 2. 5, toner box 6a and developing roller 6
A developing device 6, a transfer device 7, a cleaning device 8 and the like having the same b are sequentially provided. When the surface of the photoconductor drum 2 uniformly charged by the charger 4 is irradiated with the light image from the exposure lamp 5, an electrostatic latent image is formed on the surface of the photoconductor drum 2 according to its photoconductive property. To be done. The electrostatic latent image is developed with toner by the developing device 6. And
The toner image formed on the surface of the photoconductor drum 2 is transferred by the transfer device 7 to the recording material 9 conveyed between the photoconductor drum 2 and the transfer device 7. The toner and charges remaining on the surface of the photoconductor drum 2 after the transfer is removed by the cleaning device 8 and the charge eliminating lamp 3.

[0003]

In the prior art, many components such as the static elimination lamp 3, the charging device 4, the exposure lamp 5, the developing device 6, the transfer device 7 and the cleaning device 8 were required. There is a problem that the whole is large and the manufacturing cost is high. Therefore, a main object of the present invention is to provide an image forming apparatus capable of downsizing the entire apparatus and reducing the manufacturing cost.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a photosensitive member, a developer container in which a developer is stored, a developer is triboelectrically charged, and a thin layer of the developer is formed on the surface of the photosensitive member. An image forming apparatus comprising: a means, an exposing means for exposing a surface of a photoconductor to form an electrostatic latent image, and a transferring means for transferring a developer on the electrostatic latent image onto a recording material, which is a thin layer forming means. Has a first portion to which a bias voltage is applied and a second portion which is provided downstream of the first portion in the displacement direction of the photoconductor and to which the bias voltage is not applied, and the bias voltage applied to the first portion The image forming apparatus is configured such that the photosensitive member is charged by, and the developer is frictionally charged by the second portion.

[0005]

The bias voltage applied to the first portion of the thin layer forming means uniformly charges the surface of the photoreceptor, and the second portion of the thin layer forming means triboelectrically charges the toner. Therefore, it is not necessary to separately provide a charger and a developing roller. When the polarity of the bias voltage applied to the first portion is opposite to the charge polarity of the developer, the developer in the exposed area can be transferred to the recording material. In this case, even if a part of the developer is charged to the same polarity as the charging polarity of the photoconductor under the influence of the bias voltage applied to the first part, the polarity of the developer is changed by the frictional charging by the second part. It is possible to stabilize the polarity opposite to the charging polarity of the photoconductor.

[0006]

According to the present invention, since the number of parts can be reduced, the entire apparatus can be downsized and the manufacturing cost can be reduced. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0007]

EXAMPLE An image forming apparatus 10 of this example shown in FIG.
Is applied to a printer, a copying machine, a facsimile, or the like, and includes the photosensitive drum 12. The photosensitive drum 12 includes a transparent cylinder 12a, and a transparent conductive layer 12b and a photoconductive layer 12c are provided on the outer peripheral surface of the transparent cylinder 12a.
Are formed in this order. The photosensitive drum 12 is rotated in the arrow direction by a motor (not shown). A developing device 14 and a transfer device 16 are arranged around the photosensitive drum 12 in this order from the upstream side in the rotation direction of the photosensitive drum 12, and an exposure device 18 is arranged inside the photosensitive drum 12. It

The developing device 14 includes a toner box 22 having an opening 20 in the lower part thereof, and a developer 24 such as an insulating toner (hereinafter simply referred to as "toner") 24 is accommodated in the toner box 22. . An elastic blade 26 is attached to a downstream side portion of the opening edge of the toner box 22 in the rotation direction of the photoconductor drum 12 so that an abdomen near the free end thereof contacts the surface of the photoconductor drum 12 with a predetermined pressure. To be The toner 24 in the toner box 22 is directly supplied to the photosensitive drum 12 through the opening 20.

The elastic blade 26 includes a conductive portion 26a and an insulating portion 26b arranged downstream of the conductive portion 26a in the rotation direction of the photosensitive drum 12. In this elastic blade 26, a conductive portion 26a made of a conductive material such as metal and an insulating portion 26b made of an insulating material such as rubber or resin film are joined using a joining material such as a double-sided tape or an adhesive. Or by including a conductive additive in a part of the insulating portion 26b made of an insulating material such as rubber or resin film. In the latter case, the portion containing the conductive additive is the conductive portion 26.
a. Here, stainless steel or copper is used as the metal, butyl rubber, chloroprene rubber, urethane rubber, silicon rubber, nitrile rubber, styrene rubber or butadiene rubber is used as the rubber, and polyethylene or the like is used as the resin film. Olefin resin,
Polyacetal resin such as polyvinyl alcohol, acrylic resin such as ethylene-vinyl acetate copolymer, cellulose resin such as polycarbonate, polyamide resin such as nylon 6 or polyvinyl halide resin such as polyimide is used. Conductive additives include carbon graphite, ferrite, aluminum powder, copper powder,
Bronze powder, stainless steel powder, titanium oxide, tin oxide, metal powder or metal fiber, etc. may be used.

A bias power source 28 is connected to the conductive portion 26a, and the bias voltage of the bias power source 28 charges the surface of the photosensitive drum 12 to a predetermined polarity (positive polarity in this embodiment). Further, the toner 24 is triboelectrically charged to a predetermined polarity (negative polarity in this embodiment) by at least the insulating portion 26b. The charging polarity of the toner 24 is determined by the materials of the toner 24 and the insulating portion 26b.

The transfer device 16 includes a transfer roller 30,
A bias power supply 32 is connected to the transfer roller 30.
However, as the transfer device 16, a device using a corona discharger whose transfer voltage is controlled by a grid electrode may be used. The exposure device 18 includes the LED head array 34.
And the like, the light image from the LED head array 34 is applied to the photoconductive layer 12c of the photosensitive drum 12. An exposure point A is a point on which the light image is irradiated.

In operation, when the photosensitive drum 12 is rotated in the direction of the arrow by a motor (not shown), the surface of the photosensitive drum 12 is subjected to the electric field action of the bias voltage applied to the conductive portion 26a, as shown in FIG. Is positively charged. Further, the toner 24 supplied to the photosensitive drum 12 through the opening 20 of the toner box 22 is at least the insulating portion 26b of the elastic blade 26 (in this embodiment, both the conductive portion 26a and the insulating portion 26b).
Is negatively charged by friction. Here, even if a part of the toner 24 is positively charged by the electric field effect of the bias voltage, when the toner 24 comes into contact with the insulating portion 26b due to the rotation of the photosensitive drum 12, the toner 24 is uniformly negative. Can be triboelectrically charged. In this way, the surface of the photosensitive drum 12 is uniformly charged with the positive polarity, and the toner thin layer 36 that is uniformly charged with the negative polarity is formed on the surface of the photosensitive drum 12. Then, the thin toner layer 36 is conveyed to the exposure point A (FIG. 1). Exposure device 18
When the surface (exposure point A) of the photosensitive drum 12 is exposed by, only the surface potential V _L of the exposed portion becomes low potential, and a well type potential of the electrostatic latent image is formed as shown in FIG. .

In the transfer step, the toner 24 on the electrostatic latent image is transferred onto the recording paper 38 supplied from the paper supply means (not shown). The bias voltage V _T applied from the bias power source 32 to the transfer roller 30 is | V _S |> | V when the potential of the non-exposed portion of the photosensitive drum 12 is V _S and the potential of the exposed portion is V _L. It is set to satisfy _T │> _│VL │ (FIG. 3). Therefore, as shown in FIG. 3, the toner 24 in the non-exposed portion is subjected to the Coulomb force F _D toward the photosensitive drum 12, and the toner 24 in the exposed portion is subjected to the Coulomb force F _P toward the recording paper 38 side. , Only the toner 24 in the exposed portion is selectively transferred to the recording paper 38. The recording paper 38 on which the image is transferred is discharged to the outside after the image is fixed through a fixing device (not shown).

According to this embodiment, the elastic blade 26 to which the bias voltage is applied charges the photosensitive drum 12 and the toner 24, and further forms the toner thin layer 36 on the surface of the photosensitive drum 12. Therefore, it is not necessary to separately provide a charger or a developing roller. Therefore, the entire apparatus can be downsized and the manufacturing cost can be reduced.

In the above embodiment, the conductive portion 26
The insulating portion 2 is provided on the downstream side of the photosensitive drum 12 in the rotational direction of a.
Although the elastic blade 26 having 6b is used, the elastic blade 40 or 42 as shown in FIG. 4 or 5 may be used instead of the elastic blade 26. Elastic blade 4
0 (FIG. 4) is an elastic blade body 4 made of an insulating material.
4, a bar-shaped or strip-shaped conductive member 46 extending in the axial direction of the photosensitive drum 12 is provided at a position spaced apart from the tip of the conductive member 4 by a bias power supply 28. On the other hand, the elastic blade 42 (FIG. 5) is such that the conductive portion 48b is provided downstream of the conductive portion 48a in the rotation direction of the photosensitive drum 12 via the insulating portion 50, and the conductive portion 48a is biased. The power supply 28 is connected. Since the conductive portion 48b is shielded from the conductive portion 48a by the insulating portion 50, the conductive portion 48b is separated.
No electric field is formed in b.

Further, in the above embodiment, the photosensitive drum 1
2 is positively charged and the toner 24 is negatively charged. On the contrary, the photosensitive drum 12 is negatively charged and the toner 24 is positively charged. You may However, even in this case, the transfer bias voltage V _T is | V _S |> | V _T |> | V _L |
Must be set to satisfy (Fig. 3).

Further, in the above embodiment, the exposure device 18
However, the exposure device 18 may be arranged outside the photoconductor drum 12. Further, instead of the photosensitive drum 12, a photosensitive belt or the like may be used.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention.

FIG. 2 is an illustrative view showing a contact portion between a photosensitive drum and an elastic blade.

FIG. 3 is an illustrative view showing a well type potential of an electrostatic latent image in an exposed portion.

FIG. 4 is an illustrative view showing another elastic blade.

FIG. 5 is an illustrative view showing another elastic blade.

FIG. 6 is an illustrative view showing a conventional technique.

[Explanation of symbols]

 10 ... Image forming device 12 ... Photosensitive drum 14 ... Developing device 16 ... Transfer device 18 ... Exposure device 22 ... Toner box 24 ... Toner 26 ... Elastic blade 26a ... Conductive portion 26b ... Insulating portion 28, 32 ... Bias power source 30 ... Transfer roller 36 ... Toner thin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/08 C 15/24

Claims (4)

[Claims] 1. A photoreceptor, a developer accommodating container accommodating a developer, a thin layer forming means for frictionally charging the developer and forming a thin layer of the developer on the surface of the photoreceptor, and the photoreceptor. Exposure means for exposing the surface of to form an electrostatic latent image,
And an image forming apparatus including a transfer unit that transfers the developer on the electrostatic latent image onto a recording material, wherein the thin layer forming unit includes a first portion to which a bias voltage is applied, and the first portion. A second portion which is provided on the downstream side in the displacement direction of the photoconductor and to which the bias voltage is not applied, the photoconductor is charged by the bias voltage applied to the first part, and the second part is provided. An image forming apparatus in which the developer is triboelectrically charged. 2. The transfer means has a transfer electrode to which a bias voltage V _T is applied, the potential V _S of an unexposed portion of the photosensitive member, the potential V _L of an exposed portion of the photosensitive member and the bias. The voltage V _T and | V _S |> | V _T |> | V _L
The image forming apparatus according to claim 1, wherein the image forming apparatus is set to satisfy the condition of |. 3. The polarity of the bias voltage applied to the first portion of the thin layer forming means and the charge polarity of the developer charged by the thin layer forming means have opposite polarities.
The image forming apparatus according to claim 1. 4. The photoconductor has a translucent substrate, and a translucent conductive layer and a photoconductive layer formed in this order on the surface of the translucent substrate, and the photoconductive layer is formed by the exposing means. The image forming apparatus according to claim 1, wherein exposure is performed from the light-transmitting substrate side.