JPH0713412A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of reducing the rotational torque of a developing device without deteriorating image quality as the image forming device using the developing device. CONSTITUTION:The image forming device uses the developing device 14, where a latent image formed on a latent image carrier 11 is developed and visualized with developer carried by a developer carrier 21 by pressing the developer carrier 21 to the latent image carrier 11. A developer holding layer 23 recovering the developer left on the developer carrier 21 after development and supplying the developer to the developer carrier 21 is provided at a position under the carrier 21 in the developing device 14.

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 such as an electrophotographic printer.

[0002]

2. Description of the Related Art In a conventional developing device, particularly in a developing device for forming a uniform thin layer of a developer on a developer carrying member and supplying it to the latent image carrying member, the developer located close to the latent image carrying member. A carrier, a developer replenishing member for replenishing the developer to the developer, and a layer thickness regulating means that abuts on the developer carrier to thin the developer on the developer carrier. Developing devices are known.

Many of such developing devices are known that use a one-component toner, that is, a developer that is composed of only toner and does not contain carrier particles. In order to obtain good printing in this developing device, it is important that the layer of the developer formed on the developer carrying member is a uniform thin layer and is uniformly charged.

Therefore, conventionally, as shown in FIG.
A roller-shaped developer replenishing member (reset roller) 2 that is in contact with the developer carrying member 1 with a predetermined nip is opposed to form a uniform thin layer of toner. Reference numeral 3 denotes a layer thickness regulating member that is brought into pressure contact with the developer carrying member 1 to frictionally charge the developer and charge-charge it by applying a voltage.

[0005]

The developer replenishing member 2 is
A rotating body formed by rolling a conductive elastic body into contact with the developer carrier 1 with a certain nip width. Since both the developer carrying member 1 and the developer replenishing member 2 are rotating members and rotate in the same direction indicated by an arrow in FIG. 5 at a peripheral speed ratio, a drive motor having a large torque is required. Was there.

An object of the present invention is to provide an image forming apparatus equipped with a developing device capable of reducing the rotational torque without degrading the image quality.

[0007]

In order to achieve the above-mentioned object, in the present invention, a developer carrying member is pressed against a latent image carrying member, and the latent image carrying member is carried by the developer carried by the developer carrying member. In an image forming apparatus using a developing device for developing and visualizing a latent image formed on a body, the development remaining on the developer carrying body after development at a position below the developer carrying body of the developing device. A constitution (first constitution) is characterized by having a developer retaining layer for collecting the developer and supplying the developer to the developer carrying member.

In the image forming apparatus having the first structure, the developer holding layer is arranged along a part of the outer periphery of the developer carrying member (second structure).

Further, a developer supply amount regulating member is added to the developing device of the image forming apparatus having the above-mentioned first structure in order to prevent the supplied developer from directly going to the developer retaining layer. (3rd structure).

[0010]

Since the load on the conventional roller-shaped developer replenishing member is eliminated, the load of rotational torque is reduced, and the drive motor can be small. Therefore, the device can be downsized and the cost can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 4 is a side view showing an outline of the structure of an electrophotographic apparatus (image forming apparatus) to which the present invention is applied.
1 is a latent image carrier such as a photosensitive drum, 12 is a charging means such as a scorotron, 13 is a latent image writing means such as a laser optical unit, 14 is a one-component developing device, 15 is a transfer means such as a corotron, and 16 is heat fixing. Fixing means such as a container, 17 is a cleaning means such as a blade cleaner. Recording by this electrophotographic apparatus is performed in the following procedure.

At the time of recording, the surface of the latent image carrier 11 rotating counterclockwise as indicated by the arrow is uniformly charged by the charging means 12, and then the surface is made to respond to the image information by the latent image writing means 13. An electrostatic latent image is formed by exposing. This electrostatic latent image is developed by the one-component developing device 14 and becomes a toner image.

On the other hand, the recording sheet 100 accommodated in the sheet accommodating section is fed out at a timing which is the same as the above process and is sent between the latent image carrier 11 and the transfer means 15, where the recording by the transfer means 15 is performed. The toner image is transferred onto the paper 100. After that, the recording sheet 100 is fixed to the fixing means 16
To the stacker (not shown) after the toner image fixing is completed there.

Further, the residual toner remaining on the latent image carrier 11 after the transfer is removed by the cleaning means 17, and the residual potential on the latent image carrier 11 is removed by the discharging means (not shown). The details of the structure and operation of the one-component developing device used in the electrophotographic apparatus having such a structure and operation will be described below with reference to FIGS.

FIG. 1 is a side view of the one-component developing device 14. The one-component developing device 14 is a developer carrying member 21 which is a conductive member.
A layer thickness regulating member 22, a developer retaining layer 23, a developer hopper 24, and a developer supply amount regulating member 25.

The developer carrying member 21 conveys and supplies the developer to the developing section 26 by rotating around the rotary shaft 21a. The rotating shaft 21a is connected to a power source (not shown), and the developer carrier 21 is provided between the developer carrier 21 and the latent image carrier 11 so that electric fields in opposite directions are generated between the image portion and the background portion of the latent image. Voltage is applied to. For example, when an organic photoconductor is used as the latent image carrier 11, the image portion potential is about -100V,
Since the background portion potential is about −600V, a voltage of −300V is applied to the developer carrier 21.

As the material of the developer carrying member 21, urethane rubber, silicon rubber, NBR, porous urethane sponge or the like having conductivity can be used.

The layer thickness regulating member 22 is pressed against the latent image carrier 11 to frictionally charge the developer. In addition, the layer thickness regulating member 2
A voltage of -400 V is applied to the second electrode 2 in order to increase the amount of the electric charge by the charge injection charging. The layer thickness regulating member 22 is formed of a leaf spring whose stainless steel (SUS304) tip is round-etched.
It is attached so that the pressing pressure to 1 is 35 gf / cm.

The developer-holding layer 23 collects the developer remaining on the developer-carrying member 21 after development and supplies the developer to the developer-carrying member 21 to provide the developer-carrying member 21 on the developer-carrying member 21. It has the function of making the layer thickness of the developer uniform. The developer retaining layer 23 is a sheet-like member made of a conductive urethane sponge having a thickness of 10 mm, and a voltage is applied to the developer retaining layer 23. The developer retaining layer 23 has such a simple structure, and the roller-shaped developer replenishing member which is conventionally required can be eliminated, and the cost can be reduced.

Various conductive urethane sponges can be considered, but in this example, a cell having a cell number of about 40 cells / inch and a volume resistivity of 10 ⁴ Ω · cm was used. The developer-holding layer 23 having such a configuration is arranged on the device bottom plate 26 below the developer-carrying body 21 so that a part thereof extends along the outer diameter of the developer-carrying body 21, and the contact depth of the portion along the outer diameter. The size (compression amount) is 2 mm. The portion of the developer retaining layer 23 that does not extend along the developer carrier 21 forms an angle of about 30 ° with respect to the horizontal line.

The developer supply amount regulating member 25 is for preventing the developer dropped from the developer hopper 24 from directly falling on the developer holding layer 23. After stopping before the amount regulating member 25, it goes to the developer retaining layer 23. The shape of the developer supply amount regulating member 25 is as shown in FIG.

The developer supply amount regulating member 25A shown in FIG. 2 (A)
Is a goodwill formed of a 20 μm mylar film, and the developer supply amount regulating member 25B of FIG. 2B is a brush formed of rayon fibers having a thickness of 6 denier / filament. Mylar film and rayon fiber made of these materials are suitable for preventing excess developer from going to the developer retaining layer 23 due to its elasticity.

Further, since the resistance value of these materials can be controlled, it is possible to prevent the developer from being inappropriately charged by controlling the resistance value. It is suitable that the resistance values are both about 10 ⁴ Ω · cm (when a voltage of 100 V is applied) (such that the charging series negatively charges the toner with respect to the toner).

The developer has a volume resistivity of 4 × 10 ¹⁴ Ω · c.
m, average particle diameter 10 μm, and 0.5% silica external additive polyester toner.

An image obtained by using the one-component developing device 14 having the above-mentioned structure is compared with the conventional one, and the result is as shown in FIG. Further, the rotating torque could be reduced to 50% of the conventional value. Specifically, when a 5-phase stepping motor is used as a drive motor and the above-mentioned polyester toner having a particle size of 10 μm and silica external addition of 0.5% is used as a developer, a static torque of 1 kgf · cm, which was 2 kgf · cm in the past, is used.
reduced to cm.

For the developer carrying member 21, brush fibers having conductivity can be used in addition to the above-mentioned conductive elastic body. The brush fiber is, for example, a rayon fiber in which carbon is uniformly dispersed, and is made into a band shape having a thickness of 15 mm, and the resistance value is 10 per fiber.
Set to ³ Ω · cm. When this brush fiber was used, the same effect as described above was obtained as a result of image formation.

[0028]

As described above, according to the present invention, it is possible to reduce the rotational torque, and it is possible to realize the same image quality as the conventional one at a low cost. It should be noted that, in the present embodiment, the image forming apparatus using the one-component toner has been described, but the present invention is an alternative to the reset roller, and an image forming apparatus using a toner other than the one-component toner is used. Also by using this means, the same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a side view of a one-component developing device according to an embodiment of the present invention.

2A and 2B are shape explanatory views of a developer supply amount regulating member according to an embodiment of the present invention, FIG. 2A shows one using a mylar film, and FIG. 2B shows one having a brush shape. .

FIG. 3 is an explanatory diagram of effects of the present invention.

FIG. 4 is a side view showing a schematic structure of an electrophotographic apparatus to which the present invention is applied.

FIG. 5 is a side view showing an outline of a conventional one-component developing device.

[Explanation of symbols]

 11 latent image carrier 14 one-component developing device 21 developer carrier 22 layer thickness regulating member 23 developer retaining layer 24 developer hopper 25, 25A, 25B developer supply amount regulating member

Claims (3)

[Claims] 1. A latent image carrier (11) is attached to a developer carrier (2).
In an image forming apparatus using a developing device that presses 1) and develops a latent image formed on the latent image carrier (11) with a developer conveyed by the developer carrier (21) to visualize the latent image. , At the lower position of the developer carrying member (21) of the developing device,
An image having a developer retaining layer (23) for collecting the developer remaining on the developer carrying member (21) after development and supplying the developer to the developer carrying member (21). Forming equipment. 2. The image forming apparatus according to claim 1, wherein the developer retaining layer (23) extends along a part of the outer periphery of the developer carrying member (21). 3. The developing device of the image forming apparatus according to claim 1, further comprising a developer supply amount regulating member (25) for preventing the supplied developer from directly going to the developer retaining layer. A characteristic image forming apparatus.