JPH04279353A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus obtaining an image having no irregularity between pixels by simple drive circuit constitution. CONSTITUTION:An aperture electrode body 1 has an insulating layer 2, a reference electrode 3 and a control electrode 4 and a large number of apertures piercing them are formed in one row. A back electrode 11 feeding a support 10 in a contact state is arranged on the side of the control electrode 4 of the aperture electrode body 1. The control electrode 4 is connected to a control voltage drive circuit 8 and, when the ratio of the ON-voltage applying time and OFF-voltage applying time to the control electrode 4 is controlled according to the density data of an image signal by said circuit 8, the toner projection amount to the support 10 is modulated according to a potential applying time and gradation is expressed on the support 10.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to copying machines, printers,
The present invention relates to an image forming apparatus that can be used for plotters, facsimile machines, etc.

0002

2. Description of the Related Art Conventionally, an image recording apparatus that controls passage of toner particles through an aperture by applying an image signal to an electrode having an aperture to obtain an image on a support has been proposed in US Pat. No. 3,689,935. has been done. This proposal consists of a continuous reference electrode on one side with an insulator layer in between, and a plurality of control electrodes insulated from each other on the other side, with each insulated control electrode penetrating through three layers. an aperture electrode body having at least one row of apertures formed therein; means for selectively applying a potential between the control electrode and the reference electrode; and means for selectively applying a potential between the control electrode and the reference electrode; It consists of means for projecting modulated charged particles and means for moving the support and the aperture electrode body relative to each other.

In this system, the density of the toner particle flow is
It was modulated by the potential applied to each control electrode, and was expressed in gradations on the support.

0004

However, the above configuration requires analog operation in the control electrode drive circuit, resulting in drawbacks such as complexity of the circuit configuration and image unevenness due to variations in drive elements.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide an image forming apparatus that can obtain images without variations between pixels with a simple drive circuit configuration. There is a particular thing.

[0006]

[Means for Solving the Problems] In order to achieve this object, the image forming apparatus of the present invention has a means for selectively applying a potential between a control electrode and a reference electrode in accordance with density data of an image signal. It is characterized by comprising means for controlling the potential application time.

[0007]

According to the present invention having the above-described structure, the amount of toner projected onto the support is modulated in accordance with the potential application time, and gradation is expressed on the support.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment embodying the present invention. As shown in detail in FIG. 2, the aperture electrode body 1 has a reference electrode 3 on the toner supply source side of the insulating layer 2 and a control electrode 4 on the support side.
A large number of apertures 6 penetrating the control electrode 4 are formed in a row corresponding to the width of the support 10 (FIG. 1).

In FIG. 1, a back electrode 11 is disposed on the control electrode 4 side of the aperture electrode body 1, and is conveyed while contacting the support 10. Each control electrode 4 is connected to a control voltage drive circuit 8 that generates a voltage based on an image signal. Configure. Further, the back electrode 11 is connected to a high voltage power source 12.

On the reference electrode 3 side of the aperture electrode body 1,
A toner supply device 14 is arranged.

Control electrode drive circuit 8 is shown in detail in FIG.

The data input section 80 includes a data processing section 81
bit length equal to the number of apertures 6 for one column x
It is connected to a shift register 82 with eight times the capacity. Shift register 82 is connected to timing control circuit 83 via shift clock signal line 90. The signals output in parallel from the shift register 82 are connected to a latch circuit 84. The latch circuit 84 has latches for bytes equal to the number of apertures 6, and is connected to a latch signal line 91 from the timing control circuit 83. A comparator 85 having an 8-bit capacity receives as input the output of the latch circuit 84 for each aperture and the output of the 8-bit counter 86, and its output is connected to a high voltage switching element 87. The high-voltage switching elements are connected to an on-voltage source 88 of -150V and an off-voltage source 89 of +50V, and each output of the switching element 87 is connected to a respective control electrode 4.

The operation of the above configuration will be explained in detail below.

Positively charged toner particles are supplied by the toner supply device 14 to the vicinity of the aperture 6 on the reference electrode 3 side. At this time, when an on-voltage (-150V) is applied to the control electrode 4 according to the image signal, lines of electric force are formed in the aperture 6 of the applied control electrode 4 from the back surface to the front surface of the aperture 6. The positively charged toner is drawn out from the back surface of the aperture electrode body 1 to the front surface, and is further flown onto the support body 10 by the flying electric field formed by the back electrode 11 and held therein, and is transferred to the image area. form.

By applying an off voltage (+50V) to the control electrode 4 of the aperture electrode body 1 corresponding to the non-image area, lines of electric force are created in the aperture 6 from the front surface toward the reference electrode 3 on the back surface. This prevents toner from passing through the aperture. By repeating this process while transporting the support 10, a toner image is formed on the entire surface of the support 10.

When forming a pixel with a high density, the proportion of the on-voltage application time in one pixel formation time is increased, and when forming a pixel with a low density, the proportion is reduced, but the operation is This will be explained in detail based on FIG.

In FIG. 3, an image signal having gradation information inputted from a data input section 80 is sent to a data processing section 8.
1, each pixel is converted to 256 gradation data of 8 bits and sent to a shift register according to the arrangement of the images. When the pixel data for one column is complete, a latch signal is sent from the timing control circuit 83, and the data is held in the latch and continues to be output to the comparator. At the same time, the counter starts counting the clock signal 92 from 0 toward 255, when the formation of pixels for one column is completed. At this time, the comparator compares the count signal output from the 8-bit up counter with the pixel gradation data from the latch circuit, turns on the output until the counter output value exceeds the gradation data value, and then Turn it off until the counter finishes counting to 255. When the output from the comparator is on, the switching element 87 applies an on voltage to the control electrode 4, and when the output from the comparator is off, the switching element 87 applies an on voltage to the control electrode 4.
ff voltage is applied to the control electrode 4.

In this manner, the ratio of the on-voltage application time and off-voltage application time to the control electrode 4 is controlled in accordance with the grayscale data of the image signal within the pixel formation time for one column. As a result, the amount of toner projected onto the support 10 is modulated according to the potential application time, and gradation is expressed on the support 10.

[0020]

[Effect of the invention] As is clear from the detailed description above,
According to the present invention, since the toner flow drive time is controlled by a clock signal, it is possible to provide an image forming apparatus that can obtain an image without variations between pixels with a simple drive circuit configuration.

[Brief explanation of the drawing]

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

FIG. 2 is a perspective view showing an aperture electrode body.

FIG. 3 is a block diagram showing a configuration for controlling potential application time to a control electrode.

[Explanation of symbols] 1 Aperture electrode body 2 Insulating layer 3 Reference electrode 4 Control electrode 6 Aperture 8 Control voltage drive circuit 10 Support 11　Back electrode 12 High voltage power supply 14 Toner supply device 80 Data input section 81 Data processing section 82 Shift register 83 Timing control circuit 84 Latch circuit 85 Comparator 86 Counter 87 High voltage switching element 88 ON voltage source 89 Off voltage source

Claims (1)

[Claims] Claim 1: Consisting of a continuous reference electrode on one side with an insulator layer in between, and control electrodes formed insulated from each other on the other side, each of the plurality of insulated control electrodes has three layers. an aperture electrode body having at least one row of apertures formed therethrough; means for selectively applying a potential between the control electrode and the reference electrode; and means for supplying charged toner near the apertures of the reference electrode; In an image forming apparatus comprising a means for relatively moving a support and an aperture electrode body, the means for selectively applying a potential between the control electrode and the reference electrode applies a voltage to the gray scale data of the image signal. An image forming apparatus comprising means for controlling a potential application time accordingly.