JPH06297750A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To obtain a high density image by increasing the amt. of charged particles by extinding the contact time of the support like charged particle layer with an electric field control means by arranging the control part of the electric field control means so as to shift the same toward the downstream side of the rotary direction of a support with respect to the straight line connecting the support of charged particles and a counter electrode. CONSTITUTION:The toner 16 supplied from a supply roller 12 is slid with a carrier roller 14 and negatively charged to be supported on the roller 14 and formed into a thin layer by a layer prescribing blade 18 to be fed to an aperture electrode body 1 being an electric field control means. For example, voltage of +50V is applied to a control electrode 4 from an applying circuit 8 to form a line of electric force in the vicinity of an aperture 6 and the toner 16 is drawn out toward the control electrode 4. The toner 16 flies toward a support 12 by an electric field to be accumulated thereon to form a pixel. In this case, the center of the aperture 6 is arranged so as to be shifted toward the downstream side in the rotary direction of the carrier roller 14 with respect to the straight line connecting the centers of both of the carrier roller 14 and a counter electrode roller 22.

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 the 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. Means for selectively applying an electric potential between the reference electrode and the control electrode, and an aperture electrode body having apertures which are formed through the three members for each of the control electrodes and are arranged in at least one row And means for supplying charged toner particles so that the flow of the toner particles passing through the aperture can be modulated by the applied potential, and the support and the aperture electrode body are relatively moved to move the support in the particle flow path. And means for positioning to.

As an improved version thereof, in the application of Japanese Patent Application No. 4-254494, the aperture electrode body and the toner carrying body are arranged in contact with each other, and the toner carrying body and the control electrode of the aperture electrode body are arranged. An image forming apparatus has been proposed in which an image is formed by controlling a toner flow by an electric field formed between and.

[0005]

However, the conventional image forming apparatus as described above has the following problems in image recording. That is, at the time of recording, there is a problem that toner adheres to the toner carrier due to a mirror image force and the amount of toner supplied to the aperture electrode body decreases, and it is difficult to record a good image having a high density.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an image forming apparatus capable of excellent printing.

[0007]

In order to achieve this object, according to the image forming apparatus of the present invention, a carrier for holding and supplying charged particles, and the carrier are arranged via the charged particles. An image forming apparatus including an electric field control unit having a control unit for controlling the flow of charged particles by an electric field, and the electric field control unit being an opposing electrode arranged with an image receptor interposed therebetween, wherein the carrier is The control unit of the electric field control means is arranged on the downstream side in the rotation direction of the carrier with respect to the straight line connecting the counter electrode and the counter electrode.

[0008]

In the image forming apparatus of the present invention having the above-mentioned structure, the contact time between the charged particle layer on the carrier and the electric field control means becomes longer, which increases the adhesion of the charged particles to the carrier. Can be lowered. Therefore, a large amount of charged particles can be supplied to the electric field control means, and good recording can be performed.

[0009]

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 according to the present invention, in which a columnar shape as a counter electrode having a gap of 1 mm above the aperture electrode body 1 as an electric field control means. A back electrode roller 22 is rotatably arranged on a chassis (not shown), and is configured to be able to convey the support body 20 inserted into the gap. Further, a toner supply device 10 is arranged below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, a support body conveyed by the back electrode roller 22. A fixing device 26 is disposed at the destination of the movement of 20.

Next, the respective constituent elements will be described in detail. In the toner supply device 10, the toner case 11 also serving as the housing of the entire device, the toner 16 accommodated in the toner case 11, and the supply roller 12 are provided. And a toner carrier roller 14 as a carrier, and a toner layer regulating blade 18. Here, the toner carrying roller 14 carries the toner 16 and conveys it toward the aperture electrode body 1.
The numeral 2 supplies the toner 16 to the toner carrying roller 14.

The supply roller 12 and the toner carrying roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in FIG. Further, the toner layer regulating blade 18
Is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14. .

As shown in FIG. 2, the aperture electrode body 1 includes a polyimide insulating sheet 2 having a thickness of 25 μm, and a plurality of apertures 6 having a diameter of 100 μm formed in a row, and each of the apertures 6 on the upper surface of the insulating sheet 2. A control electrode 4 having a thickness of 1 μm is formed around the opening of the aperture 6. As shown in FIG. 3, the aperture electrode body 1 is arranged so that the control electrode 4 faces the support body 20 and the insulating sheet 2 contacts the toner 16 on the toner carrying roller 14 at the aperture position. And a straight line l connecting the center of the toner carrying roller 14 and the center of the back electrode roller 22.
On the other hand, the center of each aperture 6 is the toner carrying roller 14
Are arranged on the downstream side in the direction of rotation of.

A control voltage application circuit 8 is connected between the control electrode 4 and the toner carrying roller 14.
The control voltage application circuit 8 is configured to apply a voltage of 0 V or +50 V to the control electrode 4 based on the image signal.

Further, a DC power supply 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power supply can apply a voltage of +1 kV to the back electrode roller 22. It is like this.

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 and is negatively charged. The toner is carried on the toner carrying roller 14. The carried toner 16 is thinned and charged by the layer regulating blade 18, and then is conveyed toward the aperture 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 aperture 6.

At this time, in this embodiment, a straight line l connecting the center of the toner carrying roller 14 and the center of the back electrode roller 22.
On the other hand, since the center of the aperture 6 is arranged on the downstream side in the rotation direction of the toner carrying roller 14, the toner layer carried on the toner carrying roller 14 is not transferred to the insulating sheet 2 of the aperture electrode body 1. Sliding contact for a relatively long time reduces the adhesion of the toner to the toner carrying roller 14 due to the image force of the toner, so that a large amount of toner can be supplied to the aperture of the aperture electrode body 1 and the toner charge amount can be increased. Can be improved.

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, an electric force line from the control electrode 4 toward the toner carrying roller 14 is formed in the vicinity of the aperture 6 corresponding to the image portion due to the potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner receives an electrostatic force in the direction of higher electric potential, passes through the aperture 6 from the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 further flies toward the support 20 due to the electric field formed between the support 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and the toner 16 on the support 20 rises. To form pixels.

At this time, according to the present embodiment, since a large amount of toner is supplied to the aperture 6 of the aperture electrode body 1, it is possible to form a good image with high density, and the control voltage application circuit 8 is also provided. Therefore, a good image can be formed even if the control voltage applied to the control electrode 4 is low.

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 carrying roller 1
Toner 16 on 4 is not subjected to electrostatic force, so aperture 6
Do not pass through.

Further, the support 20 is fed by one pixel in the direction perpendicular to the aperture row 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.

If an insulating toner is used in the image forming apparatus constructed as described above, the toner carrying roller 14 is used.
The insulation between the control electrode 4 and the control electrode 4 is maintained, and the aperture 6 does not cause dielectric breakdown.

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 of the aperture corresponding to the non-image portion is set to 0V in the above embodiment, this may be a negative voltage. In this case, an image with less fogging can be obtained. Further, in the above embodiment, the aperture electrode body is used as the electric field control means, but, for example,
It is also possible to use a knitted electrode body as described in JP-A-1-503221.

[0026]

As is apparent from the above description, according to the image forming apparatus of the present invention, the adhesive force of the charged particles to the carrier can be reduced, so that a large amount of charged particles can be controlled by the electric field control means. And good recording characteristics are possible.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a configuration of an aperture electrode body used in the image forming apparatus of the present invention.

FIG. 3 is a detailed cross-sectional view showing a configuration in the vicinity of a toner carrying roller and an aperture electrode body.

[Explanation of reference numerals] 1 aperture electrode body 2 insulating sheet 4 control electrode 6 aperture 8 control voltage application circuit 14 toner carrying roller 22 back electrode roller 24 DC power supply

Claims (1)

[Claims] 1. A carrier for holding and supplying charged particles, an electric field control unit having the controller arranged via the charged particles and having a controller for controlling the flow of the charged particles by an electric field, and the electric field. In the image forming apparatus composed of the control means and the counter electrodes arranged with the image receptor interposed therebetween, the control unit of the electric field control means controls the carrier of the carrier with respect to the straight line connecting the carrier and the counter electrode. An image forming apparatus, wherein the image forming apparatus is arranged on the downstream side in the rotational direction with a shift.