JPS62258558A - Controller of plot head for electronic picture - Google Patents

Abstract

PURPOSE:To suppress the deterioration in the picture quality due to the variaton of spot intervals of a plot head by providing a control means controlling the print density parameter in response to the interval of a print spot. CONSTITUTION:A picture signal from a memory 20 is latched by a latch circuit 22 via a shift register 21. A control section 23 outputs an enable signal representing the on-time operated based on the information relating to the interval of light spots 26 to each AND circuit 24. The output of each AND circuit goes to '1' over the on-time by the enable signal and a transistor 25 is turned on. The light spot 26 is lighted by the controlled on-time through the turning-on of the transistor 25. The variaton in the luminous quantity is reduced by a span being twice the average spot interval through the control and the uneven density of image is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an electrophotographic plotting head that suppresses deterioration in image quality due to variations in spot spacing of the plotting head.

[Conventional technology]

Some electrophotographic plot heads are constructed from, for example, a light emitting diode array. FIG. 4 shows an electrophotographic device that employs this light emitting diode array.
, light emitting diode array 3 and rod lens array 4
An exposure means 5, a developing device 6, a transfer means 7, a static eliminating means 8, and a cleaning device 9 are provided, and a fixing device 10 is provided downstream of the transfer means 7.

In the above configuration, after uniformly charging the photoreceptor drum 1 with the charger 2, when the light emitting diode array 3 is driven according to an image signal, output light passes through the rod lens array 4 and exposes the photoreceptor drum 1. to form an electrostatic latent image on its surface. This electrostatic latent image is developed as a toner image by a developing device 6, and the toner image is transferred onto recording paper by a transfer means 7. The toner image transferred to the recording paper 4 is fixed by a fixing device 10 to complete the recording. On the other hand, the photoreceptor drum 1
After the static electricity is removed in step 1, it is cleaned in cleaner 9.

FIG. 5 shows the light emitting diode array 3, which has 64 light emitting spots 31.31A, 31r--- in the main scanning direction.
112 (for example, in the case of A2 sipes) are arranged.

[Problem that the invention seeks to solve]

However, according to the conventional electrophotographic apparatus, as shown in FIG. 5, the semiconductor chip 32.32A.

When manufacturing the light emitting diode array 3 by cutting 32B--------- from a wafer and pasting it on a substrate, the spot spacing varies (120 μm) as shown between semiconductor chips 32A and 326, for example. )
Therefore, when the spot spacing becomes large, there is an insufficient amount of light, and for example, in the case of reversal development, the density of the image formed decreases in that area, resulting in a deterioration in image quality.

In Figure 6 (a), the distance between spots 4 and 5 is the standard value of 1.3.
It shows that the light intensity is doubled and all spots are 1.
If the same value (standard value) is set for 2.3, -. Figure 6 (
B) shows that there is no variation in the interval between spots 1.2.3, . . . , and all spots 1.2.
3, . . . - emit light with a standard value.

These problems are not unique to light emitting diode arrays, but are also common to electrophotographic devices that use heating element arrays or charging element arrays (stylus heads).

- [Means for Solving the Problems] The present invention has been made in view of the above, and in order to suppress the deterioration of image quality due to variations in the spacing of the printing spots due to light emission, heat generation, charging, etc. Print density parameters (light emission amount, heat generation amount, amount of charge, etc.) depending on the interval between
The present invention provides a control device for an electrophotographic plot designed to control.

Hereinafter, a control device for an electrophotographic plotting head according to the present invention will be described in detail.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which a memory 20 storing an image signal, an image signal inputted from the memory 20 as a serial signal 1nS, and a parallel signal 1. a shift register 21 that outputs a
The AND circuit 24 outputs under the AND condition of the output of 2 and the enable signal ■ of the control unit 23;
Switching transistor 2 is turned on by the output of
5, and a light emitting spot 26 that lights up when the switching transistor 25 is turned on.

The control unit 23 stores information regarding the intervals between the light emitting spots and controls the operation of each circuit.

To explain the operation in the above configuration, memory 2
The serial image signal I- from 0 is transferred to the shift register 21.
, the parallel image signal 11. It is latched by the launch circuit 22 as p. The control unit 23 calculates the ON time (
Outputs enable signal ■E with duty ratio). Second
Figure (A) shows this, and the luminous spot 26. ．． 26□,
Luminous spots 264 and 2 in 263・---1---
6. If the gap is larger than other gaps, the control unit 23 inputs data 231.23! , 23. Based on -..., an enable signal (2) is output to the corresponding AND circuit 24, which increases the on-time of the light emitting spots 264 and 265 at both ends of the large interval by 1.3 times (130%) as the standard. The control unit 23 simultaneously controls the light emitting spots 264 and 26. The light emission amount is 0.7 times (70%) and 1.3 times (1
31 stones), and an enable signal V controlled to be 0.7 times (70%). This enable signal (2) causes the AND circuit 24 to become "1" for a time period corresponding to its on time, turning on the switching transistor 25 (when the image signal is "1").

By turning on the light emitting spot 26 (26,, 26□,
263-...-) emit light based on the controlled on-time, and emit light with the amount of light shown in FIG. 2(b). Figure 2 (b) shows light-emitting sub-nods 264 and 26. indicates that the interval is 1.3 times the standard value, and at the same time, the light intensity is 1.3 times the standard value, and 0.7 in both directions (in the main scanning direction).
It shows that the control is repeated in the following order: 1.3 times, 1.3 times, 0.7 times, etc. With this control, variations in the amount of light can be reduced when viewed over a span (interval) that is twice the average spot interval g (2Xg), and density unevenness in the image can be reduced.

FIG. 3 shows another embodiment in which the spot spacing is large, W
In this embodiment, the amount of correction of the amount of light is made smaller as the distance from S9 increases, and the influence of parts with large intervals on parts with uniform intervals is avoided as much as possible.

Although the above embodiment has been described as an example of a plotting head having a light emitting diode array, it goes without saying that the present invention can also be applied to the control of the heating element of a thermal head, the control of the charging element of the throat of a stylus, etc.

〔Effect of the invention〕

As described above, according to the control device for an electrophotographic plot head of the present invention, the print density parameter is controlled according to the spacing of the printing spots, so that deterioration in image quality due to variations in the spacing of the printing spots can be avoided. It can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention. Figure 2 (a), (
B) is an explanatory diagram showing a control state according to the present invention. FIG. 3 is an explanatory diagram showing another embodiment of the present invention. FIG. 4 is an explanatory diagram showing an electrophotographic recording device. FIG. 5 is an explanatory diagram showing a light emitting diode array. FIGS. 6A and 6B are explanatory diagrams showing conventional control states. Explanation of symbols 20--Memory 21--Shift register 22--Launch circuit 23--Control section 26 (26,, 26□, 26:lt'--)-・・・
・-Light-emitting Subop Patent Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Hei 1) Tadao (Ino)

Claims (1)

[Scope of Claims] An electrophotographic plot head having an array of printing spots driven in accordance with an image signal, further comprising a control means for controlling a printing density parameter according to an interval between the printing spots. A control device for an electrophotographic plot head, characterized in that: