JPS61255366A - Method for controlling quantity of light of led - Google Patents

Abstract

PURPOSE:To compensate the temp. characteristic of gallium arsenide LED and to supply always specified exposing energy so that imaging quality is maintained by detecting the temp. of an LED array and changing the duty ratio of a quantity of light control signal according to the temp. change. CONSTITUTION:An LED control part 1 feeds imaging information and the quantity of light control signal 7 to the LED array 3. The signal 7 is of a chopper type and the duty ratio thereof is controlled by the control part 1. The temp. of the LED array 3 changing with the frequencies of imaging is detected by a temp. sensor 6 and is fed to the control part 1. The control part 1 makes the control action to increase the duty ratio of the signal 7 with an increase in the temp. of the array 3 and to decrease the duty ratio with a decrease in the temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an LED light quantity control system, and in particular to an LED light quantity control system in an exposure type printing apparatus using 1c LEDs.

[Conventional technology]

Conventionally, this type of LED exposure type printing apparatus has an LED control unit 11 and a large number of LEDs 2 integrated as shown in FIG.
It consisted of an ED array 3 and a photosensitive drum 5. Third
The figure is a block diagram showing an example of the conventional LEDi 1 light D 31 arrangement. The LED control unit 11 sends print information and a light emission signal 4 to the LED array 3, and creates a latent image of this print information on the photosensitive drum 5. do.

[Problem that the invention seeks to solve]

To achieve high quality printing, it is desirable that the exposure energy given to the photosensitive drum 5 be within a certain range determined by the characteristics of the photosensitive drum 5.

Its exposure energy t-! It is determined by the product of the light emission energy from the LED 2 and the light emission time TO. Here, the luminescence time T
is uniquely determined by the size of one printed dot, the rotational speed of the photosensitive drum 50, and the size of the LED 2.

At present, most of the LEDs commonly used are 2fl gallium foliar type. Fig. 4 is a diagram showing an example of the characteristics of the temperature and luminous energy of a typical LED. As the temperature rises, the luminous energy decreases.

Therefore, in conventional LED exposure type printing devices, even if the temperature changes due to the energization of the 7j LED 2 depending on the printing frequency, this is not compensated for, so the exposure energy changes and the printing quality cannot be maintained constant. There are drawbacks.

[Defined means of solving problems]

The present invention includes an LED based on the LED quantity control system of the present invention, an LED array in which a large number of the LEDs are integrated, a constant temperature sensor attached to the LED array, and a light quantity control signal to the LED array using the output of the temperature sensor as input. It also includes an LED control section that outputs.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing an embodiment of the 0LED light amount control system of the present invention, and FIG. 2 is a time chart showing a comparison between the light amount control signal in FIG. 1 and the light emission signal in FIG. 3.

In FIG. 1, an LED control section 1 is attached to an LED array 3 and receives the output of a constant temperature sensor 6 as input. Further, the LED array 3 receives a light amount control signal 7 from the LED control section 1 as input, and the light amount of the LEDs 2 is controlled.

Next, the operation of this embodiment will be explained.

The LED control section 1 sends print information and a light amount control signal 7't- to the LED array 3. The light amount control signal 7 is in the form of a chip, as shown in FIG.
g D $3 Controlled by control section 1.

The temperature of the LED array 3, which changes depending on the printing frequency or VC, is detected by the temperature sensor 6 and sent to the LED control section 1. The LED control unit 1 performs a control operation such that when the temperature of the LED array 3 rises at 9 o'clock, the duty ratio of the light amount control signal 7 is increased, and when the temperature decreases, the duty ratio is decreased.[Effects of the Invention] As explained above, the present invention compensates for the temperature characteristics of the gallium arsenide LED by detecting the temperature of the LED array and changing the duty ratio of the light amount control signal according to the change in temperature, so that the temperature characteristics of the gallium arsenide LED are always constant. This has the effect of supplying exposure energy to maintain printing quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the LED quantity control method of the present invention, and FIG. 2 shows a comparison of the light amount control signal in FIG. 1 and the light emission signal in FIG. FIG. 3 is a block diagram showing an example of a conventional LED exposure type printing apparatus, and FIG. 4 is a diagram showing an example of the temperature and emission energy characteristics of a general LED. 1.11...LEDfllt! + Gobe, 2...
...I, ED, 3...LED array,
4... Light emission signal, 5... Photosensitive drum,
6... Temperature sensor, 7... Light amount control signal. Agent Patent Attorney Hara Uchi −′′″′°)−−：
5' Minej Kaimine4Tfi

Claims (1)

[Claims] The present invention includes an LED, an LED array in which a large number of the LEDs are integrated, a temperature sensor attached to the LED array, and an LED control unit that receives the output of the temperature sensor as an input and outputs a light amount control signal to the LED array. Features LED light amount control method.