JPH0375764A - Electrophotographic printer having led head - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of a light emitting LED head without depending on characteristics by providing an exposing time correcting section and correcting the exposing time in such a manner that the light of the exposure of an average level value is emitted from the LED. CONSTITUTION:The exposing data quantities 5 of the respective LEDs 4 are received in a data holding section 1 and are transmitted to the exposing time correcting section 2. The correcting section 2 judges an LED driving section 3 in such a manner that the light 5 of the exposure of the average level value is emitted from the LEDs 4. The corresponding driving signal is applied to the driving section 3 to operate the LEDs 4. The light 5 of the exposure generated in such a manner is detected by an exposure detecting section 6 and is fed back to the correcting section 2 according to the exposure. Then, the correcting section 2 resets exposure correcting time according to the fed back quantity. The exposing time of the LEDs is incorporated into the device in this way without being largely dependent upon the characteristics of the LEDs and the adjustment is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrophotographic printers having light emitting diode (LED) heads, and more particularly to exposure time correction of LED heads.

[Conventional technology]

Conventionally, this type of LDE head has exposure time correction! Yonaku,
The configuration had only a data holding section and an LED driving section.

[Problem to be solved by the invention]

In the conventional LED head described above, each L during exposure
Since the ED exposure level is greatly influenced by the characteristics of each individual LED, it is necessary to perform a unit test on each individual LED, and there are disadvantages in that it is difficult to adjust the LED head as a device.

[Means to solve the problem]

The electrophotographic printer of the present invention includes an LED head section, a data holding section, an exposure time correction section, an LED driving section, and an LED
It has an exposure amount detection section.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic diagram of the present invention, and FIG. 2 is a diagram showing signals output from the exposure time correction section of FIG. 1. TMIN + TMAX on the time axis in Figure 2 is the LED during that time.
These are the minimum and maximum values of the driving time within a range in which the printing results of the device do not give a visually strange feeling even when exposed to light. The data holding unit 1 of the first part receives the exposure-on data of each LED,
It is transmitted to the exposure time correction section 2. The exposure time correction unit 2
So that light 5 with an average level of exposure comes out from ED4.
This is to determine the LED driving section 3, and a driving signal 7 corresponding to the average exposure amount shown in FIG. 2(a) is set and applied to the LED driving section 3 to operate the LDE 4.

As a result, an exposure amount 5 is generated, and the exposure amount detection section 6 applies feedback to the exposure time correction section 2 according to the exposure amount. In the exposure time correction section 2, the exposure correction time is reset steplessly or in multiple steps according to the amount of feedback.For example, when the exposure amount 5 is small, driving for a smaller exposure amount is performed as shown in FIG. 2(b). TMIN < T O < 71≦TM for signal 8
Set with the time of Ax.

Conversely, when the exposure amount 5 is large, the drive signal 9 for the large exposure amount is set to T VIN≦T 2 < as shown in FIG. 2(b).
It is possible to correct the LED exposure time with a configuration of 0 or more, which is set at a time such that T O < TMAX.

〔Effect of the invention〕

As explained above, the present invention has the advantage that by correcting the exposure time of the LED head, it is possible to easily fine-tune the device without being greatly dependent on the characteristics of individual LEDs.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the peripheral portion of the LED head of the present invention, and FIGS. 2(a) to 2(C) are waveform diagrams of signals output from the exposure time correction section of FIG. 1. 1... Data holding section, 2... Exposure time correction section, 3.
...LED drive unit, 4...LED, 5...exposure amount,
6... Exposure amount detection unit, 7... Drive signal for average exposure amount, 8... Drive signal for small exposure amount, 9
... Drive signal for multiple exposure amounts.

Claims (1)

[Claims] LED head section, data holding section, exposure time correction section, LE
An electrophotographic printer with an LED head, characterized by including a D drive section and an LED exposure amount detection section.