JPS61264768A - Device for driving recording element array - Google Patents

Abstract

PURPOSE:To correct any difference in recorded data in a recording element array without substantially increasing the scale of circuits, by providing a line memory for storing picture signals, a memory circuit in which a number of times of recording in one-line scanning is set as a correction data based on the amount of data recorded in each element and a control circuit supplying the picture signals to a driving circuit for driving the recording element array according to the correction data. CONSTITUTION:Picture signals inputted from a picture signal input terminal 4 are stored in a line memory 5. The stored signals are read out for (n) times during one line scanning and inputted into a control circuit 7. The control circuit 7 selectively supplies the picture signals to a driving circuit 3, based on correction data from a memory circuit 6. That is, the picture signals are recorded for (n) times while one line is scanned, and the period of time for which electric current is applied to each element is changed by changing the number of times of recording. Further, more times of recording are performed for the elements emitting smaller amount of light, while fewer times of recording are performed for the elements emitting larger amount of light, so that any difference in amount of light among the various elements is properly corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording element array driving apparatus such as a light emitting element array driving apparatus used in an optical writing head of an electrophotographic process.

BACKGROUND ART Conventionally, a light emitting element array driving device as this type of device is
The configuration was as shown in Figure 6.

Based on the image signal applied from the image signal input terminal 1o4, the current from the power input terminal 101 is controlled by the drive circuit 102 and applied to the light emitting element (LED) array 1o3.

Problems to be Solved by the Invention However, with the conventional configuration, there is a phenomenon in which variations in the light emission of the I4D array occur due to variations in the characteristics of each LED element and drive circuit. The problem was that it was growing.

This problem arises from the fact that in order to correct variations in the characteristics of each LED element and drive circuit, it is generally necessary to have a correction circuit for each element and control the current application time or applied current value for each element. It happened for a reason. Further, this is equally true not only for IICDs but also for recording elements such as heat-sensitive elements.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a recording element array driving device that can correct recording variations in a recording element array without significantly increasing the circuit scale. shall be.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention includes a line memory for storing image signals, and a memory for setting the number of recordings in one line scan as correction information based on the recording amount for each recording element. and a control circuit that supplies an image signal to a drive circuit for the recording element array based on the correction information.

The image signal output from the active line memory is read out a predetermined number of times by the control circuit during one line scan based on correction information for each recording element stored in the storage circuit, and is supplied to the drive circuit.

Embodiment FIG. 1 shows an embodiment of the present invention, in which L is used as a recording element.
1 is a schematic block diagram showing an LED array driving device using an ED.

This LED array drive device is an L
It has an ED array 1, a power input terminal 2, a drive circuit 3 for driving the LED array, and a drive circuit 3 that stores -line image signals input from the terminal 4, and operates in synchronization with a clock signal from a clock terminal CLK. The line memory 5 is also provided with a line memory 5. Further, this device includes a storage circuit 6 in which correction information for the image signal is stored and operates in synchronization with a clock signal from a clock terminal OLE, similar to the line memory 6, and an image signal inputted from the line memory 5. The control circuit 7 controls the correction information based on the correction information in the storage circuit 6 and supplies the control information to the drive circuit 3.

In the line memory 5, image signals are read out a plurality of times (for example, n times) in synchronization with a clock signal during -line scanning, thereby dividing one line scanning time into n divisions. Further, as shown in FIG. 2, for example, the control circuit 7 includes an AND gate 71L that performs a logical AND operation between the image signal input from the line memory 5 and the correction information input from the storage circuit 6.
The output is supplied to the drive circuit as a corrected image signal (or converted image signal).

The storage circuit 6 stores, for each LICD element, correction information on the number of times of recording according to the amount of light emitted, corresponding to the number of readings n, so that each LED can obtain the same output for the same line input image signal. I remember it as. This memory circuit 6
For example, the configuration shown in FIG. 3 is taken. This memory circuit 6 is arranged horizontally as 1, 2, .・・・・・・a, b,・
・・・・・・Arranged in bits corresponding to p and each LED element, 1, 2 degrees in the vertical direction...3...xl,...
・x2t...n and the readout times for this memory circuit 6 (
(corresponding to the recording amount in the LED array) is stored as address information. For example, for an element that emits a small amount of light, such as the first LID element, on information "1" is written so that it emits light for all reading times, while for the second LED element, Thus, off information "0" is written to elements that emit a large amount of light so as to stop emitting light at an early readout time, thereby forming correction information as a whole. The correction information is used to correct the input image signal, so that the amount of light emitted from each LzD element is made uniform for input image signals on the same line.

Next, the operation will be explained.

The image signal input from the image signal input terminal 4 is stored in the line memory 6. Thereafter, it is read out once during line scanning and input to the control circuit 7. The control circuit 7 selectively supplies the image signal to the drive circuit 3 based on the correction information from the storage circuit 6 . That is, in this embodiment, recording is performed n times during -line scanning, and by changing the number of recordings, the current application time of each element is changed. Furthermore, by performing recording more times for elements that emit less light and fewer times for elements that emit more light, variations in light amount of each element are corrected.

The operation for correcting variations in the amount of light emitted will be explained with reference to FIGS. 3 and 4. As already mentioned, the number of readings and the number of recordings during -line scanning are both n, and the memory circuit 7 has each light emitting element 1°2.3. ...a, ...b
, . . . correction information that takes into account variations in the amount of light emitted by p is stored. Here, in the line memory 5, as shown in FIG.
Assume that an image signal pix as shown in is input. Then, the control circuit 7 reads this image signal from the line memory 5 n times during one line scan, while reading the correction information corresponding to each readout from the storage circuit 7, and calculates the logical product between both data. The calculation result is output to the drive circuit 3 as a recording image signal p1x (corrected image signal). Looking at the corrected image signals output in this way for each number of recording times, the results are as shown in Fig. 4). That is, for the first light emitting element, data "1°" for turning it on for all reading times is stored in the memory circuit 7.
The corrected image signal can also be driven for all recording ports.

On the other hand, the light emitting element corresponding to the 1st bit has x1
A drive signal is emitted up to the X++th time, but no drive signal is emitted from the X++1st time onwards. Further, a drive signal is emitted to the light emitting element corresponding to the fifth bit up to x2 times, but no drive signal is emitted from x2,011 times. Note that since the second and p-th pits have 0'' data from the beginning, the corresponding light emitting elements are not driven.

In this way, while the first input image signal pix is read out once, each bit is converted into bits based on the correction information n, and is supplied to the drive circuit 3 as a corrected image signal pix.

If such operations are taken into consideration comprehensively, as shown in FIG. 6, recording is performed n times during -line scanning time to, and the element with a smaller amount of emitted light is This means that by increasing the number of times x2 is recorded, the total amount of light emitted during -line scanning is made the same.

Although the above description is about light amount variation correction, the present invention can be used for all operations that control the amount of light emitted by each element.

Effects of the Invention As is clear from the above explanation, according to the present invention, image signals selectively supplied based on correction information set for each recording element in advance are recorded multiple times during one line scan, so that each Since the current application time can be controlled for each recording element without having a current application time control circuit for each recording element, it is possible to control the recording amount for each recording element and correct recording variations. .

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an m*) array driving device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the control circuit shown in FIG. 1, and FIG. 3 is a block diagram showing an example of the control circuit shown in FIG. FIG. 4(a) shows an example of an input image signal to the line memory shown in FIG.
(b) is a diagram showing an example of a corrected image signal output from the control circuit in response to this input image signal, FIG. 6 is a light emission time timing chart of the device shown in FIG. 1, and FIG.
FIG. 1 is a schematic block diagram showing an example of an ED array driving device. 1...LED array, 3...drive circuit, 6...line memory, 6...memory circuit, 7...control circuit . Name of agent: Patent attorney Toshio Nakao and one other IR
Toshi-ku Keiwa - Etsuha Goro
False, Ward-7-7 Beak t

Claims (1)

[Claims] a recording element array in which a plurality of recording element arrays are arranged; a drive circuit for driving the recording element array; a line memory for storing image signals; and a storage circuit for storing read count information set for each recording element; a control circuit that reads the image signal inputted from the line memory for the number of times of reading for each corresponding recording element based on the number of readings information inputted from the storage circuit, and selectively supplies the readout signal to the drive circuit; A recording element array drive device comprising: