JPH07125298A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To output an image of a high quality at a high speed by efficiently supplying toner under a recording edge. CONSTITUTION:An edge electrode 1 as toner flow control means of an image forming apparatus has control electrodes 4 and a control voltage applying circuit 8 disposed on an insulation sheet 2 made of polyimide having a thickness of 25mum. The many electrodes 4 are formed at an internal of 125mum from the edge of one end of the electrode 1 with a width of 100mum and a thickness of 1mum. The electrode 1 is opposed to the electrode 4 of a support 20 side at a downstream side of toner conveying by rotation of a toner carrier roller, and so disposed that the sheet 2 is brought into contact with the toner on the roller at the edge, and brought into pressure contact with a toner layer by a retaining member 7.

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 which can be used in copying machines, printers, plotters, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses, an electrode having a plurality of openings (hereinafter referred to as apertures) is used, and a voltage is applied to the electrode based on image data. U.S. Pat. No. 3,689,935 discloses controlling toner particles so that they can pass through the aperture and forming an image on a support by the toner particles that have passed.

This image forming apparatus comprises a flat plate made of an insulating material, a continuous reference electrode formed on one surface of the flat plate, and a plurality of control electrodes insulated from each other formed on the other surface. , An aperture electrode body having at least one row of apertures formed through each of the control electrodes, and a means for selectively applying a potential between the reference electrode and the control electrode. A means for supplying charged toner particles so that the flow of toner particles passing through the aperture is modulated by an electric potential, and a means for positioning the support in the particle flow path so that the support and the aperture electrode body can move relative to each other. It consists of and.

Further, as proposed in Japanese Patent Publication No. 1-503221, there is one in which the passage of toner is controlled by a grid electrode matrix to obtain an image on a support.

However, according to these devices, the toner particles are clogged in the apertures to deteriorate the recording quality, and
I couldn't make the recording speed too fast.

[0006] The applicant of the present invention further studied, and, as already filed in the application of Japanese Patent Application No. 4-254494, brings the carrier holding the toner into contact with the toner flow controller such as the aperture electrode body. An image forming apparatus is also proposed in which the recording characteristics can be greatly improved by arranging the same. According to this apparatus, the aperture of the aperture electrode body is not clogged, and the image quality is remarkably improved, and the image forming apparatus can be downsized and reduced in cost.

[0007] The applicant of the present invention filed Japanese Patent Application No. 5-47848.
As described in the specification and drawings of No. 6, by eliminating small holes and mesh stitches from the toner flow control body,
We have proposed an image forming apparatus that uses an edge electrode body that is easy to manufacture and does not clog, and as a result is inexpensive and that can output high-quality images over a long period of time.

[0008]

However, in the image forming apparatus using the edge electrode body as the toner flow control body as described above, the toner is supplied from the control electrode side to below the edge which is the toner flow control section. It was as a result,
When a voltage that causes toner to fly toward the support is applied to the control electrode, part of the supplied toner adheres to the edge due to the electric field formed between the edge electrode body and the toner carrier.
It hindered the supply of toner below the edge and reduced the print speed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of outputting a high-quality image at high speed.

[0010]

In order to achieve this object, an image forming apparatus of the present invention comprises an edge electrode body for controlling the flow of charged toner, and a toner carrier for supplying the charged toner to the edge electrode body. The body and the toner carrier have a back electrode provided on the opposite side with the edge electrode body sandwiched therebetween, and by controlling the charged toner to pass while flying in the vicinity of the edge electrode body, An image is formed on a support disposed on the opposite side of the toner carrier from the edge electrode body, and the toner flying toward the support is the toner of the edge electrode body. The edge electrode body is configured and arranged so that it can pass near the end located on the upstream side in the supply direction.

[0011]

In the edge electrode body of the image forming apparatus of the present invention having the above-described structure, the toner flying toward the support passes near the edge of the edge electrode body located upstream in the toner supply direction. Configured and arranged to obtain. As a result, a part of the toner adheres to the back of the edge electrode body due to the electric field between the edge electrode body and the toner carrier, and holds the toner under the edge. A large amount of toner can be controlled because the toner stays under the edge which is under the control electric field.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of an image forming apparatus of the present invention, in which an edge electrode body 1 as toner flow control means is provided.
A back electrode 22 is disposed on the upper side of. The back electrode 22 is installed so as to be vertically movable within a predetermined range,
It is biased downward by the pressing spring 23. A pressing member 7 having a thickness of 0.5 mm is fixed to the upper surface of the edge electrode body 1, and when the supporting body 20 is conveyed to the gap between the back electrode 22 and the pressing member 7 by this, the pressing member 7 is pressed. With the member 7, the gap between the support 20 and the edge electrode body 1 is 0.5.
The edge electrode body 1 can be held by the pressing spring 23 via the holding member 5 and the support body 20 while being kept at mm.

A toner supply device 10 is arranged below the edge electrode body 1 along the longitudinal direction of the edge electrode body 1, and at the carry-in side of the edge electrode body 1.
A transport roller 29 for transporting the support 20 between the edge electrode body 1 and the back electrode 22 is rotatably arranged, and further, the support 20 transported beyond the back electrode 22 advances. The fixing device 26 is arranged at the front.

Next, the respective components will be described in detail. In the toner supply device 10, the toner case 11 also serving as a housing of the entire device, the toner 16 housed in the toner case 11, and the supply roller 12 are provided. And a toner carrying roller 14 and a toner layer regulating blade 18. Here, the toner carrying roller 1
Reference numeral 4 is for carrying the toner 16 and carrying it toward the edge electrode body 1. The supply roller 12 is for supplying the toner 16 to the toner carrying roller 14.
Then, the supply roller 12 and the toner carrying roller 14
Is rotatably supported in the toner case 11 in the direction of the arrow shown in FIG. Also,
The toner layer regulating blade 18 is the toner carrying roller 1
The amount of toner 16 carried on the roller 4 is adjusted so as to be uniform on the roller surface, and the toner 16 is pressed against the toner carrying roller 14.

In the edge electrode body 1, as shown in FIG. 2, a control electrode 4 and a control voltage applying circuit 8 are formed on a 25 μm thick insulating sheet 2 made of polyimide. A large number of control electrodes 4 are formed with a width of 100 μm and a thickness of 1 μm at intervals of 125 μm from the recording edge portion 6 which is one end of the edge electrode body 1. In the edge electrode body 1, as shown in FIG. 1, the control electrode 4 is made to face the support body 20 on the downstream side of the toner conveyance by the rotation of the toner carrying roller, and the insulating sheet 2 carries the toner at the recording edge portion 6. It is arranged so as to be in contact with the toner on the roller, and is pressed against the toner layer by the pressing member 7.

The control electrode 4 is connected to a control voltage applying circuit 8 as shown in FIG. This control voltage application circuit 8 controls the control electrode 4 to 0 based on the image signal.
It is configured to apply a voltage of V or + 50V.

Further, a DC power source 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power source is + with respect to the back electrode roller 22.
A voltage of 1 kV can be applied.

Next, the operation of the image forming apparatus configured as described above will be described.

First, by rotating the toner carrying roller 14 and the supply roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying roller 14 to be negatively charged. The toner is carried on the toner carrying roller 14. Toner 1 carried
The layer 6 is thinned by the layer regulating blade 18 and is conveyed toward the edge electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied below the recording edge portion 6 of the edge electrode body 1.

Here, in accordance with the image signal, the control voltage applying circuit 8 adds + to the control electrode 4 corresponding to the image portion.
A voltage of 50V is applied. As a result, due to the potential difference between the control electrode 4 and the toner carrying roller 14, an electric force from the control electrode 4 toward the toner carrying roller 14 is generated near the recording edge 6 portion corresponding to the image portion and on the back surface of the control electrode. A line is formed. As a result, the negatively charged toner on the back surface of the control electrode receives an electrostatic force in the direction of higher potential, and adheres to the back surface portion 9 of the control electrode shown in FIG. As a result, the toner conveyance is delayed, and the toner is not transferred to the recording edge 6
Collect below. This toner is transferred from above the toner carrying roller 14 to the recording edge portion 6 by the electric field between the recording edge and the control electrode.
And is drawn to the control electrode 4 side. The extracted toner 16 further flies toward the support body 20 due to an electric field formed between the support body 20 and the edge electrode body 1 due to the voltage applied to the back electrode 22, and on the support body 20. To form pixels.

A voltage of 0V is applied from the control voltage application circuit 8 to the control electrode 4 corresponding to the non-image portion.
As a result, since no electric field is formed between the toner carrying roller 14 and the control electrode 4, the toner 16 on the toner carrying roller 14 is not subjected to electrostatic force. Therefore, the toner passes through without adhering to the back surface of the control electrode, and does not receive the electrostatic force in the direction of the control electrode to pass through the recording edge portion 6.

Further, the support 20 is fed by one pixel in the direction perpendicular to the recording edge while the toner 16 forms one row of pixels on the surface thereof. Then, the toner image is formed on the entire surface of the support 20 by repeating the above process. Then, the formed toner image is fixed on the support 20 by the fixing device 26.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, although the control voltage corresponding to the non-image portion is set to 0V in the above embodiment, it may be a negative voltage. In this case, an image with less fogging can be obtained.

Further, in the above-mentioned embodiment, the one having the recording edge portion which is linear is used as the toner flow control means.
This is a step difference as shown in FIG.
It is also possible to use a saw-toothed blade as shown in (b). In this case, even if the support is transported in a direction perpendicular to the arrangement of the control electrodes, there is an effect that a space is less likely to be generated between dots formed on the support.

Further, although the control electrode is arranged on the side of the insulating sheet facing the support in the above embodiment, it may be on the toner supply side. In this case, since the distance between the control electrode and the toner carrier is close to the thickness of the insulating sheet, the control electric field of the same strength can be formed with a lower control voltage.

[0028]

As is apparent from the above description, according to the image forming apparatus of the present invention, since the control electrode is not provided on the upstream side of the toner supply, the toner is supplied to the toner supply surface of the control electrode of the edge electrode body when the toner is turned on. Does not interfere with the toner supply to the recording edge portion. Further, since the control electrode is arranged on the downstream side of the toner supply, if the toner adheres to the toner supply surface of the edge electrode body at the time of turning on, the toner is collected under the recording edge, so that the toner supply efficiency is good. Therefore, a high-quality image can be output at high speed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a top view showing a configuration of an edge electrode body.

FIG. 3 is a diagram showing a periphery of a recording edge of an edge electrode body of the image forming apparatus.

FIG. 4 is a top view showing a modified example of the edge electrode body.

[Explanation of symbols]

 1 Edge Electrode 4 Control Electrode 6 Recording Edge 8 Control Voltage Application Circuit 14 Toner Carrier Roller 22 Back Electrode Roller 24 DC Power Supply

Claims (1)

[Claims] 1. An edge electrode body for controlling the flow of charged toner, a toner carrier for supplying charged toner to the edge electrode body, and the toner carrier provided on the opposite side of the edge electrode body. And a back electrode that is provided on the opposite side of the edge electrode body so as to control the passage of the charged toner while flying in the vicinity of the edge electrode body. In an image forming apparatus for forming an image on a body, the toner flying toward the support can pass through the edge electrode body in the vicinity of an end located upstream of the edge electrode body in the toner supply direction. An image forming apparatus characterized by comprising and arranging.