JPH04362976A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To closely contact a developing roller and a photosensitive drum, or the developing roller and the surface of a developing blade, without providing a layer having elasticity on the surface of the developing roller, and simultaneously, to obtain an electrophotographic device having a long service life. CONSTITUTION:In the developing device having the developing roller 1 and the developing blade 3, the developing roller 1 is composed of a pipe 21, a shaft 23 constituting a rotary shaft, and a flange 22 elastically supporting the pipe 21 on the rotary shaft 23, and the developing blade 3 is made of a material having high hardness. Thus, a constitution that the electrophotographic device having the long service life can be produced at low cost, can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a developing device for an electrophotographic non-impact printer. especially,
The present invention relates to a developing device that uses non-magnetic one-component toner.

0002

2. Description of the Related Art The printing process of an electrophotographic non-impact printer consists of charging, exposure, development, transfer, fixing, neutralization, and cleaning processes.

[0003] Applying static charge uniformly to the surface of the photoreceptor in a dark place,
Light is irradiated onto the charged photoreceptor. Then, the resistance of the photosensitive layer in that area decreases, and the charge (-) escapes. Here, an invisible electrostatic latent image corresponding to the printed image is formed between the areas exposed to light and the areas not exposed to light. When the (-) charged toner is brought into contact with the photoreceptor, the toner adheres to the electrostatic latent image due to electrostatic force. Lay paper on top of this,
Charges of opposite polarity to the toner (
When a charge (+) is applied to the paper, the toner is attracted to the charge and moves to the paper. That is, the toner image formed on the photoreceptor surface is transferred onto the paper. Heat and pressure are applied to the toner transferred onto the paper to fuse it to the paper.

The image forming (charging, exposure, development, transfer) section will be explained below. FIG. 3 is a mechanical diagram showing the image forming section of the electrophotographic printer. As shown in the upper part of FIG. 3, the developing device of an electrophotographic printer includes a toner cartridge 31, a stirring shaft 32, a toner guide plate 33, a sponge roller 34, a developing roller 35, a photosensitive drum 36, a developing blade 37, a charger 38, and a cleaning blade. 39 and auger shaft 40.

The toner cartridge 31 contains toner 4 inside.
When the cartridge 31 is filled with toner 41 and set in the developing device, the toner 41 inside is fed into the developing device from inside the cartridge 31, and all the toner 4
Only the toner cartridge can be replaced after 1 is consumed.

[0006] The stirring shaft 32 is connected to the toner cartridge 3.
It is provided below the toner supply port No. 1. The stirring shaft 32 has a shape in which a coiled wire is wound around the shaft.

The toner guide plate 33 has a plurality of small round holes and is provided below the stirring shaft 32. A sponge roller 34 is arranged below, a developing roller 35 is arranged in contact with the sponge roller 34, and a photosensitive drum 36 is arranged in contact with the developing roller 35.

The developing blade 37 is attached to the surface of the developing roller 35 so as to be in contact with a certain pressure, and a sealing material is pasted on the upper part of the developing blade 37 to prevent the toner 41 from leaking.

The cleaning blade 39 is constructed by bonding a rubber material to a sheet metal, and the edge portion of the rubber material is in contact with the surface of the photosensitive drum 36. An auger shaft 40 with spiral blades is located below the cleaning blade 39, and is connected to the stirring shaft 32 via an auger shaft inside a side plate (not shown).

The charger 38 uniformly charges the surface of the photosensitive drum 36, and is placed near the drum, and a print head 42 is provided next to it. A transfer device 43 is arranged directly below the photosensitive drum 36, and the paper 44 is configured to pass between the photosensitive drum 36 and the transfer device 43.

Next, the operation will be explained. When the toner cartridge 31 is set in the developing device, the toner 41 inside falls onto the stirring shaft 32 and the toner guide plate 33. The fallen toner 41 is uniformly supplied in the axial direction by the stirring shaft 32 and sent to the sponge roller 34 through the hole in the toner guide plate 33.

When the main motor (not shown) is driven, all the shafts connected to the main motor with gears rotate in the direction of the arrow. Toner 41 on the surface of the sponge roller 34
is supplied to the developing roller 35. The toner 41 on the surface of the developing roller 35 is made into a thin layer by the developing blade 37.
It is supplied to the photosensitive drum 36. The surface of the photosensitive drum 36 is charged (-) by the charger 38, and only the area where the light from the print head 42 hits is tilted toward the (+) side. Then,
Since the toner 41 on the surface of the developing roller 35 is negatively charged, the toner 41 is supplied only to the area hit by the light from the print head 42, and an image is formed.

The image on the photosensitive drum 36 is transferred from the surface of the photosensitive drum 36 to the surface of the paper 44 by a transfer device 43 when the paper 44 passes directly under the photosensitive drum 36, and is fixed by a fixing device (not shown).

After the image has been transferred to the paper 44, the cleaning blade 39 removes all the toner 41 remaining on the surface of the photosensitive drum 36 to form the next image.

The toner 41 removed by the cleaning blade 39 is sent to a side plate (not shown) by an auger shaft 40, and is again supplied to the stirring shaft 32 by the auger shaft 40 in the side plate.

[0016] In such a developing device, the
As described in the 6070 publication, the developer blade 37 is made of metal coated with a material that is separated from the toner 41 with respect to the friction zone sequence. Specifically, a synthetic resin, a resin and injection material, or a metal coated with a polymer is used as the coating material.

[0017]

However, in such a developing device, the entire surface of the developing roller is coated with an elastic layer in order to ensure proper contact between the surface of the photosensitive drum and the surface of the developing roller. Here, the elastic layer on the surface of the developing roller needs to be formed uniformly and not easily peeled off. Furthermore, if this elastic layer is formed of rubber or the like, the deposition resistance of this rubber layer will be 10 to the 6th power Ω to 1
It needs to be within an extremely narrow range of 0 to the 8th power Ω. Since it is technically difficult to satisfy such conditions, there has been a problem that the developing roller and, by extension, the electrophotographic apparatus become expensive.

The coating material of the developing blade 37, which is a synthetic resin, a resin and an injection material, or a polymer, is
It is easily scraped by the abrasive material contained in the toner, and after a short period of use, the developing blade becomes uneven, making it impossible to form a uniform toner layer on the developing roller. That is, there was a problem that the life of the developing blade was short and high print quality could not be maintained.

[0019]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has a developing blade and a developing roller that is in contact with the developing blade, and the toner formed on the developing roller is In an electrophotographic developing device that develops an electrostatic latent image on a photosensitive drum in a layer, the developing roller is configured to be elastically supported by a shaft that is a rotation axis of the roller. be.

The second invention includes a developing blade and a developing roller that is in contact with the developing blade, and an electronic device that develops an electrostatic latent image on a photosensitive drum with a toner layer formed on the developing roller. The photographic developing device is characterized in that the developing blade is made of a material with high hardness.

[0021]

[Operation] Since the present invention is constructed so that the roller is supported by the elastic flange as described above, the developing roller body can be held elastically even without providing an elastic layer over the entire surface of the developing roller. Therefore, the developing device and the developing roller can be brought into contact with each other reliably. In the present invention, since the developing blade is made of a material with high hardness as described above, wear of the developing blade can be reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an electrophotographic developing apparatus for explaining an embodiment of the present invention. The electrophotographic developing device includes a developing roller 1, a developing blade 3 that comes into contact with the developing roller 1 to adjust the adhesion thickness of toner 2 on the developing roller 1, a holder 4 that holds the developing blade 3, and a holder 4. It has a spring 5 that adjusts the pressing force of. Developing roller 1
contacts the photosensitive drum 6 and supplies toner onto the photosensitive drum 6 to a predetermined thickness.

The developing roller 1 is composed of a pipe 21, an elastic flange 22, and a shaft 23 provided at the center of the elastic flange 22, as shown in FIG.

[0024] The pipe 21 is formed of an aluminum pipe, a brass pipe, or a stainless steel pipe. Note that any material other than metal may be used as long as it is hard and conductive. The surface of the pipe 21 is treated with sand blowing, etc., and has a thickness of 2 μm to 10 μm.
It is preferable to have a surface roughness between .

Here, when the pipe 21 is made of aluminum, it is preferable to anodize the surface, but when it is made of a metal pipe other than aluminum, it is preferable to coat the surface with a resin coating layer such as polycarbonate. is preferred. Here, the resin coat layer is provided with a thickness of 30 μm or less. The reason why the coat layer should be 30 μm or less is because even if the coat material is an insulator (including a high-resistance material of 10 to the 10th power Ωcm or more), if the coat thickness is 30 μm or less, the electrical insulation will be insufficient. This is because it exhibits semiconductivity. Thereby, the charges accumulated on the surface of the pipe 21 can be effectively released through the elastic flange 22, which will be described next.

The elastic flanges 22 support both ends of the pipe 21. The elastic flange 22 is made of conductive rubber, sponge, resin, or metal treated with a spring, and holds the pipe 21 with elasticity or flexibility. Since the pipe 21 is held elastically by the elastic flange 21 in this manner, it can rotate eccentrically even if it is fixed to the shaft 23 serving as the rotation axis. The developing roller 1 rotates while being in contact with the photosensitive drum 6 in an elastic state. The developing roller 1 is supplied with a developing bias voltage or grounded. Therefore, the developing roller is required to be semiconductive.

The developing blade 3 is formed of a metal plate such as an aluminum plate, a brass plate, or a stainless steel plate, a glass plate, a ceramic plate, or the like. The surface roughness of the surface of the developing blade 3 that comes into contact with the developing roller 1 is treated by sand blasting or the like.
Preferably, the average roughness is between 2 μm and 10 μm. Even if the developing blade 3 is made of a material with intermediate characteristics in the friction band series, the surface roughness of the developing blade 3 and the developing roller 1 allows the toner to adhere well to the surface of the developing roller 1. The developing blade 3 is held by a holder 4 and is pressed toward the developing roller 1 by a spring 5. The toner 2 is made into a thin layer by the developing blade 3 during the rotation of the developing roller 1. The thinned toner layer on the developing roller 1 adheres to the photosensitive drum 6 according to the electrostatic latent image on the photosensitive drum 6, forming a toner image on the photosensitive drum 6. Here, it is preferable that the developing blade 3 is formed of a glass plate because the glass material has positive polarity characteristics in the friction band series and has excellent characteristics for negatively charging the toner 2.

In a non-contact type developing device in which the developing roller 1 and the photosensitive drum 6 are arranged at a certain distance, a spacer is inserted between the developing roller 1 and the photosensitive drum 6, so that the developing roller Even if the rotating shafts of the developing roller 1 and the photosensitive drum 6 are eccentric, it is absorbed by the elastic flange 22 of the developing roller 1, making it possible to maintain a constant interval.

[0029]

[Effects of the Invention] As explained in detail above, according to the present invention, the following effects can be obtained.

First of all, since the developing roller is composed of an elastic flange and a hard pipe, there is no need to cover the surface of the developing roller with an elastic layer. Therefore, the developing roller can be manufactured easily and at low cost.

Second, since the surface of the developing roller is roughened, a thin toner layer can be efficiently formed on the surface of the developing roller.

Thirdly, since an insulating layer of 30 μm or less is formed on the surface of the developing roller made of an electrically conductive material, this surface becomes semiconductive and the charges accumulated on the surface can be effectively discharged. Furthermore, since this insulating layer can be made of a highly hard material such as resin, it is more resistant to abrasion and has a longer service life than a conventional developing roller whose surface is coated with rubber or the like.

Fourthly, since the developing blade is made of a material with high hardness, it is possible to extend the life of the developing blade, thereby facilitating maintenance of the electrophotographic developing apparatus.

Fifth, since the developing blade is made of a material with high hardness, there is no wear on the contact surface even if the developing blade constantly applies pressure to the developing roller formed of an elastic flange and a hard pipe. It is particularly suitable for use in a developing roller formed of the elastic flange and hard pipe of the invention.

[Brief explanation of drawings]

FIG. 1 is a side view of an electrophotographic developing device showing an embodiment of the present invention.

FIG. 2 is an external view of a developing roller used in the present invention.

FIG. 3 is a cross-sectional view of a general electrophotographic device.

[Explanation of symbols]

1 Developing roller 3 Developing blade 4 Holder 5 Spring 6 Photosensitive drum 21 Pipe 22 Elastic flange 23 Shaft

Claims (8)

[Claims] 1. An electrophotographic developing device comprising a developing blade and a developing roller in contact with the developing blade, and which develops an electrostatic latent image on a photosensitive drum with a toner layer formed on the developing roller. . An electrophotographic developing device, wherein the developing roller is elastically supported by a shaft that is a rotation axis of the roller. 2. The electrophotographic developing device according to claim 1, wherein the surface of the developing roller is made of metal. 3. The electrophotographic developing device according to claim 2, wherein the developing roller has a surface roughness of 2 to 10 μm. 4. The electrophotographic developing device according to claim 1, wherein the surface of the developing roller has a high resistance layer having a thickness of 30 μm or less. 5. The electrophotographic developing device according to claim 1, wherein the elastic body has electrical conductivity. 6. An electrophotographic developing device comprising a developing blade and a developing roller in contact with the developing blade, which develops an electrostatic latent image on a photosensitive drum with a toner layer formed on the developing roller. . An electrophotographic developing device, wherein the developing blade is made of a material with high hardness. 7. The electrophotographic developing device according to claim 6, wherein the material with high hardness is glass or ceramic. 8. The electrophotographic developing device according to claim 6, wherein the roller contacting surface of the developing blade has a surface roughness of 2 μm to 10 μm.