JPH03289681A - Optical printer - Google Patents

Abstract

PURPOSE:To always irradiate a photosensitive body with the light of an optimum light quantity even when the variation of surface potential to exposure is changed and even when the performance of an exposing device is deteriorated by measuring the surface potential before and after test exposure and deciding the light quantity so that the optimum surface potential may be obtained. CONSTITUTION:The surface potential of the photosensitive body 1 before and after the test exposure which is designated by a test exposure designating means 7 is measured by a photosensitive body potential measuring means 4. A light quantity control means 5 decides the optimum light quantity of the exposing device 3 based on the measured surface potential of the photosensitive body 1 before and after the test exposure, and the photosensitive body 1 is irradiated with the light of the optimum light quantity which is decided from the exposing device 3 in the case of forming a desired electrostatic latent image on the photosensitive body 1. Even when the variation of the surface potential to the exposure is changed because of the change of temperature and humidity and even when the performance of the exposing device 3 is deteriorated, the photosensitive body 1 is always irradiated with the light of optimum light quantity with which the optimum surface potential is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical printer equipped with an exposure device that irradiates a charged photoconductor with light to form an electrostatic latent image on the photoconductor. .

[Prior Art] As a conventional optical printer equipped with an exposure device, there is one described, for example, in Japanese Patent Application Laid-Open No. 62-246080.

This optical printer measures the surface potential of the photoconductor only when it is not exposed to light, and based on the surface potential, adjusts the energization time of the exposure device so that the optimal photoconductor surface potential is obtained after exposure. It controls the

[Problems to be Solved by the Invention] However, in the conventional optical printer, the amount of change in surface potential with respect to exposure of a specific amount of light changes due to changes in temperature and humidity. There were problems in that the desired surface potential could not be obtained and stable image density and resolution could not be obtained.

Further, even if the performance of the exposure device deteriorates, even if the exposure is carried out for a predetermined energizing time, the amount of exposure will be insufficient and the desired surface potential will not be obtained.

The present invention has been made by focusing on the above-mentioned conventional problems, and it is possible to always obtain an optimal photoreceptor surface potential even when changes in temperature and humidity occur, deterioration in the performance of the exposure device, etc.
An object of the present invention is to provide an optical printer that can obtain stable image density and resolution.

[Means for Solving the Problems] An invention related to an optical printer that is distantly related to the above object includes an exposure device that irradiates a charged photoconductor with light to form an electrostatic latent image on the photoconductor. An optical printer comprising: a photoreceptor potential measuring means for measuring the surface potential of the photoreceptor;
A test exposure instruction means for instructing the exposure device to perform a test exposure, and forming a desired electrostatic latent image on the photoreceptor based on the surface potential of the photoreceptor before and after the test exposure. , a light amount control means for controlling the light amount of the exposure device so as to obtain an optimum surface potential.

Here, the light amount control means subtracts a predetermined specific potential from the surface potential before the test exposure, and the optimum surface potential for forming a desired electrostatic latent image on the photoreceptor. an optimum surface potential calculation means for calculating, and a correlation determination means for determining a correlation between the surface potential of the photoconductor and the light amount of the exposure device from the surface potential before and after the test exposure. The method may further include a light amount calculating means for calculating a light amount of the exposure device when forming a desired electrostatic latent image on the photoreceptor from the obtained optimum surface potential and the determined correlation. preferable.

Note that the optical printer in this application is a concept that includes not only a general printing device but also a copying device.

[Effect: The surface potential of the photoreceptor before and after the test exposure instructed by the test exposure instruction means is measured by the photoreceptor potential measuring means.

The light amount control means determines the optimum light amount of the exposure device based on the measured surface potential of the photoreceptor before and after the test exposure.

When forming a desired electrostatic latent image on the photoreceptor, the determined optimum amount of light is irradiated from the exposure device.

Therefore, the amount of light before and after the test exposure can be measured and the amount of change in surface potential can be ascertained, so even if the amount of change in surface potential with respect to exposure changes due to changes in temperature or humidity, the performance of the exposure device may deteriorate. However, the photoreceptor can always be irradiated with the optimum amount of light that provides the optimum surface potential.

[Embodiments] Hereinafter, embodiments of the present invention will be described based on the construction drawings to FIG. 3.

As shown in FIG. 1, an optical printer includes a photoreceptor 1 on which an electrostatic latent image is formed, a charger 2 that charges the surface of the photoreceptor 1, and an exposure device that irradiates light onto the photoreceptor 1. 3, and a potential measurement sensor 4 for measuring the surface potential of the photoreceptor.

A light amount control circuit 5 that controls the amount of light from the exposure device 3 based on the measured surface potential is connected to the potential measurement sensor 4 and the exposure device 3. The amount of light is determined by adjusting the exposure time of the exposure device 3.

The light amount control circuit 5 includes a CPU and a memory (not shown). 5 Optimum surface potential V of the photoreceptor 1. an optimum surface potential calculation means for determining the correlation between the surface potential V of the photoconductor 1 and the light intensity of the exposure device 3, a correlation determining means for determining the potential ■-light intensity curve, and the determined potential V- Light intensity curve and optimum surface potential determined ■.

Optimum light intensity. The light amount calculation means for calculating the amount of light is executed by the CPU operating based on a program stored in the memory in the light amount control circuit 5.

An exposure instruction circuit 7 that instructs the exposure device 3 to perform exposure is connected to the light amount control circuit 5 .

The exposure instruction circuit 7 instructs the exposure device 3 to perform exposure according to instructions from an operator, and also instructs test exposure.

The exposure device 3 is connected to an exposure pattern generation circuit 6 that instructs an exposure pattern.

The exposure pattern generation circuit 6 can generate exposure pattern data desired by the operator and specific exposure pattern data for the test exposure.

The exposure device 3 is an LED II, as shown in FIG.

11, . . . , a data latch 8 that holds exposure pattern data from the exposure pattern generation circuit 6, and AND gates 9, 9 . . . that add signals from the data latch 8 and the light amount control circuit 5. ...and AND gate 9.9. The drivers 10, 10 . . . open the LED II, 11° . . . in response to signals from . It is equipped with...

The photoreceptor potential measuring means is constituted by a potential measuring sensor 4, the light amount control means is constituted by a light amount control circuit 5, and the test exposure instruction means is constituted by an exposure instruction circuit 7.

Next, the operation of this embodiment will be explained.

When the optical printer is started, the photoreceptor is charged by the charger 3.

A potential measurement sensor 4 measures the surface potential V of the charged photoreceptor 1.

The optimum surface potential calculation means of the light amount control circuit 5 calculates the optimum surface potential V when forming a desired electrostatic latent image based on ■□.

Calculate.

Measured surface potential V1 and optimal surface potential V. Which potential difference a is always almost constant, so the optimal surface potential V can be calculated using the following formula:
. is calculated.

V□-a=V0 Next, specific exposure pattern data is output from the exposure pattern generation circuit 6 to the exposure device 3, and at the same time, the exposure instruction circuit 7
As a result, the exposure device 3 is instructed to perform test exposure.

Then, LED II of exposure device 3, 11. ...of which...
a specific LEDI corresponding to the specific exposure pattern data;
I, 11. ...only emit light.

A specific electrostatic latent image is formed on the surface of the photoreceptor 1 in accordance with the specific exposure pattern data.

The potential measurement sensor 4 measures the surface potential v2 of the exposed portion of the photoreceptor 1.

As shown in FIG. 3, the correlation determining means of the light amount control circuit 5 determines the relationship between the surface potential V and the light amount based on the initially measured surface potential 1 and the subsequently measured surface potential V2. A potential V-light intensity curve showing the correlation is determined.

The light amount calculation means of the light amount control circuit 5 calculates the determined potential V.
- Optimal light intensity based on the light intensity curve and the calculated optimum surface potential V0. Calculate.

When printing the print data desired by the operator, the photoreceptor 1 is neutralized and then charged again by the charger 2 . And LEDII, 11. - is the calculated optimal light amount. It emits light for the exposure time corresponding to the time.

Optimal surface potential ■ for photoreceptor 1. A desired electrostatic latent image is formed.

Therefore, the surface potential before and after the test exposure■□.

■ After measuring 2 and understanding the amount of change in surface potential, determine the optimal surface potential V. Since the amount of light is determined to obtain the optimum amount of light, even if the amount of change in surface potential with respect to exposure changes due to changes in temperature or humidity, or even if the performance of the exposure device 3 deteriorates, the amount of light will always be optimal. can be irradiated onto the photoreceptor.

The reason why a specific exposure pattern is used during the test exposure is that the surface potential v2 of the photoreceptor 1 after the test exposure is always obtained from the same electrostatic latent image during the test exposure. This is to minimize unstable factors when determining the correlation between (1) and the amount of light.

In this embodiment, the exposure device was configured with an LED. However, the present invention does not limit the exposure device to a light emitting element such as an LED. For example, the exposure device is not limited to a light emitting element such as an LED. It may also be applied to devices that operate on

[Effects of the Invention] According to the present invention, the amount of light is determined to obtain the optimum surface potential after measuring the surface potential before and after test exposure and understanding the amount of change in surface potential. Even if the amount of change in surface potential in response to exposure changes due to changes in light or humidity, or even if the performance of the exposure device deteriorates, the optimal amount of light can always be irradiated onto the photoreceptor, resulting in stable image density and resolution can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of an optical printer, FIG. 2 is a block diagram of an exposure device, and FIG. 3 is a graph showing the relationship between surface potential and light amount. position measurement sensor, 5... light amount control circuit, 6... pattern generation circuit, 7... exposure instruction circuit.

Claims (1)

[Claims] 1. In an optical printer equipped with an exposure device that irradiates a charged photoreceptor with light to form an electrostatic latent image on the photoreceptor, the surface potential of the photoreceptor is measured. a photoreceptor potential measuring means; a test exposure instruction means for instructing the exposure device to perform a test exposure; 1. An optical printer comprising: a light amount control means for controlling the light amount of the exposure device so that an optimum surface potential is obtained when forming an electrostatic latent image. 2. The optical printer according to claim 1, wherein the test exposure instruction means instructs the exposure device to form a specific electrostatic latent image on the photoreceptor. 3. The light amount control means subtracts a predetermined specific potential from the surface potential before the test exposure to determine the optimum surface for forming a desired electrostatic latent image on the photoreceptor. an optimum surface potential calculating means for calculating a potential; and a correlation determining means for determining a correlation between the surface potential of the photoconductor and the light amount of the exposure device from the surface potential before and after the test exposure. , from the determined optimal surface potential and the determined correlation,
3. The optical printer according to claim 1, further comprising a light amount calculating means for calculating a light amount of the exposure device when forming a desired electrostatic latent image on the photoreceptor.