JPH05232800A - Developing device and image forming device equipped with it - Google Patents

Abstract

PURPOSE:To refrain from applying stress to a developer when the transport amount of developer is restricted and the developer is charged electrostatically. CONSTITUTION:A developer holding member 42 formed cylindrically from a mesh-form sheet is installed rotatably while confronting a photo-sensitive drum 15 which bears a latent image, and a fur brush 44 is furnished in contact with the inside of this developer holding member 42 for transporting tone developer and charging electrostatically, and a voltage impressing means 48 is provided to impress a bias voltage on the developer holding member 42 and supply latent image with developer which is transported up by the for brush 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image or a magnetic latent image using powder toner, and an image forming apparatus equipped with this developing device.

[0002]

2. Description of the Related Art In a developing device having a structure for visualizing a latent image with a one-component developer, a metal blade is brought into contact with a rotatable developer holding member to charge the developer and form a layer of the developer. is doing. The developer layer on the developer holding member thus formed is supplied to the latent image formed on the photosensitive drum to develop the latent image.

[0003]

However, in the prior art, since the metal blade is brought into contact with the developer holding member to charge the developer and form a layer, the developer is easily stressed and the development is unstable. There is a problem of turning into.

Therefore, an object of the present invention is to provide a developing device capable of being charged and supplied to a developer without applying stress, and an image forming apparatus equipped with this developing device.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a developing electrode rotatably provided facing an image bearing member carrying a latent image and formed in a tubular shape by a mesh thin plate. And a rotatable fur brush which is provided in contact with the inner surface of the developing electrode to convey and charge the developer, and a developer which is applied by a bias voltage to the developing electrode and is conveyed by the fur brush. To the latent image.

[0006]

The developer is charged to a predetermined polarity by the fur brush, the charged developer is conveyed to the mesh-shaped developing electrode by the fur brush, and the conveying force pushes the developer to the opposite side of the developing electrode. By applying a bias voltage to, it is possible to develop without using a developer thin layer forming means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 2 shows the internal structure of an electrophotographic image forming apparatus using a semiconductor laser.

The image forming apparatus (laser printer) is connected to a host system (not shown) which is an external output device such as an electronic calculator or a word processor via a transmission controller such as an interface circuit. When a print start signal is received from the host system, the image recording operation is started, and the image is recorded on a sheet as a material to be transferred and output. This image forming apparatus has the following configuration.

That is, reference numeral 1 in the drawing denotes a main body of the image forming apparatus, and an electrophotographic process unit 3 as an image forming means for forming an image is arranged on the upper side of the main body 1 and is provided on the upper front side. The paper discharge unit 6 is formed.
Further, the lower part of the inside of the apparatus main body 1 is provided with the paper feed cassettes 7a,
It is a cassette housing portion 8 for housing b. The paper discharge unit 6 is a recess formed on the front upper surface of the apparatus body 1. Further, the apparatus main body 1 located on the left side of the paper discharge unit 6
A control panel 11 is arranged on the upper surface of the left frame portion of the. Next, the electrophotographic process unit 3 for performing a series of image forming operations such as charging, exposure, development, transfer, peeling, cleaning and fixing will be described.

A drum-shaped photosensitive member 15 as an image bearing member is arranged at a substantially central portion of the unit 3, and a charging means 16 composed of a scorotron is provided around the photosensitive member 15 along its rotation direction. An exposure unit 17a of a laser exposure unit 17 as an exposure unit (electrostatic latent image forming unit),
A magnetic brush type developing means 18 for performing a developing step and a cleaning step, a transfer roller 19, a cleaning means 20 composed of a blade and an auger are sequentially arranged.

Further, in the apparatus main body 1, the paper P fed from the paper feeding cassettes 7a and 7b through the paper feeding means 22 and 52 is provided between the photoconductor 15 and the transfer roller 19. A paper transport unit 24 is formed which leads to the paper discharge unit 6 provided on the upper surface side of the apparatus main body 1 via the image transfer unit 23.

Further, the image transfer portion 2 of the paper transport path 24
A pair of aligning rollers 25 and a pair of conveying rollers 26 are arranged on the upstream side of 3, and a fixing unit 27 and a pair of discharging rollers 28 and 29 as a discharging means are arranged on the downstream side.

When the print start signal is received by the host system, the drum-shaped photoconductor 15 rotates and the photoconductor 15 is charged by the charging means 16. Next, the laser beam a modulated by receiving the dot image data from the host system is scanned and exposed on the photoconductor 15 using the laser exposure unit 17 including the polygon mirror scanner 30 to form an image signal on the photoconductor 15. Form a corresponding electrostatic latent image. The electrostatic latent image on the photoconductor 15 is developed and visualized by toner as a developer of the developing device 18.

On the other hand, the paper P taken out from the paper feeding cassette 7a or 7b in synchronization with the toner image forming operation.
Is transferred through the aligning roller pair 25, and the toner image previously formed on the photoconductor 15 is transferred to the paper P by the function of the transfer roller 19. Then paper P
Is sent to the fixing unit 27 through the paper transport path 24. The fixing unit 27 includes a heat roller 31 accommodating the heater lamp 12 and a pressure roller 32 pressed by the heat roller 31.
The toner image is fused and fixed on the paper P by passing between the two. Then, after this, the pair of discharge rollers 28, 29
The sheet is discharged to the sheet discharge unit 6 via.

After transferring the toner image on the paper P,
The residual toner remaining on the photoconductor 15 is removed by the cleaning unit 20 including a blade to remove the memory, and is conveyed in the drum axial direction by the auger and collected in a box (not shown). By the way, the developing device 18 is configured as shown in FIG. That is, reference numeral 41 in the drawing denotes a developing container, and the developing container 41 contains a toner as a component as a developer.

Further, in the developing container 41, a developer holding member 42 as a developing electrode is provided rotatably, which is cylindrically formed of a mesh thin plate. A casing 47 is provided inside the developer holding member 42, and the first conveying screw 43 is provided inside the casing 47.
Further, the first fur brush roller 44 is rotatably arranged. The outer surface of the developer holding member 42 and the fur brush roller 44 are in contact with each other.

A second conveying screw 45 and a fur brush roller 46 are rotatably arranged outside the developer holding member 42. The outer surface of the developer holding member 42 and the second fur brush roller 46 are in contact with each other. The first and second conveying screws 43 and 45 convey one-component toner in opposite directions, and deliver the toner at both ends thereof.

The first far brush roller 44 is also used.
A first bias applying means 48 is connected to the
The bias applying means 48 applies a DC bias voltage to the first far brush roller 44.

Further, the developer holding member 42 has a second
Is connected to the second bias applying means 49, and a DC bias voltage is applied by the second bias applying means 49.

In this embodiment, the toner conveyance amount is set so that the toner always stays in the developing nip portion of the first far brush roller 44, and the excess toner moves on the developer holding member 42. The toner that has been peeled off by the fur brush roller 44 or the toner that has been peeled off is mixed with new toner by the conveying screw 45, and this toner is conveyed again to the fur brush roller 44 by the conveying screw 43. Incidentally, in this embodiment, the fur brush roller 4 is used.
3, 46 are conductive and have a thickness of 600D / 100F,
Density 100000F / inch ² Are used. The developer holding member 42 is a stainless steel plate having a thickness of 0.15 mm, the mesh hole diameter is circular with a diameter of 86 μm, and the pitch is 151 μm.

The surface of the developer holding member 42 is 5 to 10
By applying a resistance or insulation coating of about 0 μm, it is possible to suppress the transfer of electric charge (discharge) with the photosensitive drum 12, and as a component for improving the chargeability of the toner during the coating. Blending a known charge control agent is also effective in improving the developing characteristics.

Further, the toner is negatively charged with an average particle size of 6 μm, an organic photoconductor is used as the photoconductor drum 12, and the surface potential is −550V. Further, a developing bias voltage of −200V is applied to the developer holding member 42, and a bias voltage of −300V is applied to the fur brush roller 44. In addition, the rotation direction of the fur brush roller 44 is
The direction is opposite to that of the photosensitive drum 15.

Further, the entire developing container 41 is replaced with the photosensitive drum 15
By bending the developer holding member 42 as a structure to be pressed against, the developing gap between the photosensitive drum 15 and the developer holding member 42 is maintained at 10 μm. On the other hand, it rotates in the direction opposite to the photosensitive drum 15, that is, in the width direction at a speed of 1.5 times.

During development, the toner is fed by the rotation of the first feeding screw 43, and the toner is supplied to the fur brush roller 44 through the through hole 47a in the partition wall of the casing 47. This toner is conveyed by the rotation of the fur brush roller 44, rubs between the inner wall surface of the casing 47 and the fur brush roller 44, and is charged to a predetermined polarity.

The proper amount of toner charged to the predetermined polarity is further conveyed to a position facing the developer holding member 42. The toner is supplied to the photoconductor drum 15 through the mesh of the developer holding member 42 by the pressure of the fur brush roller 44 and the electric field between the fur brush roller 44 and the developer holding member 42, and the electrostatic latent image is generated. Develop the image. As described above, by rotating the far brush roller 44,
Since the toner is charged by rotating the toner, the stress at the time of charging the toner can be reduced. Further, the toner remaining on the developer holding member 42 is a far brush roller.
The rotation of the la 46 removes the stress on the toner so that it is removed.

[0026]

As described above, according to the present invention, the supply of the developer to the developing electrode and the stress applied to the developer at the time of charging the developer are reduced, and stable and uniform development is performed. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a developing device that is an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an image forming apparatus including the developing device of FIG.

[Explanation of symbols]

15 ... Photosensitive drum (image carrier), 42 ... Developer holding member (developing electrode), 44 ... Fur brush, 48 ... Voltage applying means.

Claims (3)

[Claims] 1. A developing electrode, which is rotatably provided so as to face an image bearing member carrying a latent image and has a cylindrical shape by a mesh-shaped thin plate, and is provided in contact with the inner surface side of the developing electrode. A rotatable fur brush that conveys and charges the developer, and a voltage applying unit that applies a bias voltage to the developing electrode and supplies the developer conveyed by the fur brush to the latent image. A developing device. 2. An image bearing member carrying a latent image, an image forming means for forming a latent image on the image bearing member, a rotatably provided facing the image bearing member, and a cylinder made of a mesh thin plate. -Shaped developing electrode, a rotatable fur brush which is provided in contact with the inner surface of the developing electrode and which conveys the developer and charges the developing electrode, and applies a bias voltage to the developing electrode to generate the fur brush. An image forming apparatus comprising: a voltage applying unit that supplies the developer conveyed by the latent image to the latent image. 3. The developing device according to claim 1, further comprising a removing far brush that comes into contact with the outer surface of the developing electrode and removes the developer remaining on the developing electrode.