JPS63172287A - Method for correcting light quantity of light emitting diode array - Google Patents

Abstract

PURPOSE:To eliminate unevenness in the quantity of light on the light receiving side even if an optical axis is shifted by measuring the quantity of light emitted from a light emitting diode through a lens array and adjusting a light emitting time based on the measured value. CONSTITUTION:Under the united state of a light emitting diode (LED) array head 3 with a self-focusing lens array (SLA) 9, respective LEDs 7 are turned on and the quantity of light emitted through the SLA 9 is individually measured in each LED and the measured value is stored in a road-only memory (ROM). Then, the LED array head 3 and the SLA 9 are built in an LED printer and the memory is also built in a light quantity correcting circuit. In case of recording an image, the measured values of light quantity emitted from respective LEDs 7 are read out from the memory, the light emitting time is adjusted by addition/subtraction on the basis of the measured values and the quantity of incident light upon the surface of a photosensitive drum 1 on the light receiving side is corrected so as to be fixed. Even if the optical axis of the LEDs 7 is shifted from that of the SLA 9, unevenness in the quantity of light on the light receiving side can be sharply reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for correcting light-emitting diode arrays in printers and the like that use light-emitting diode arrays as light sources.

[Conventional Techniques@] With the spread of Japanese word processors and combi coaters, more and more people are printing out sentences, figures, and various data created by these devices, and various output devices have been developed for this purpose. It has come to be.

A laser printer is a typical non-impact printer that forms an electrostatic latent image on a photoreceptor. A laser printer scans the surface of a photosensitive drum with a laser beam at high speed, and forms an electrostatic latent image of image data by controlling the on/off of the laser beam. The formed electrostatic latent image is developed by a developing device to create 1 to ner images. The toner image is transferred to the printing paper and fixed.

Laser printers can perform printing operations at high speed. However, an optical system such as a polygon mirror is required for beam scanning, making the apparatus expensive and large. Another disadvantage is that a sophisticated control circuit is required to correct the optical system.

Therefore, recording apparatuses such as printers have been developed in which scanning of an optical image on a photoreceptor is performed using a light emitting diode (LED).

FIG. 3 shows the basic structure of an LED printer device using this LED. This device includes a photosensitive drum 1 for forming electrostatic latent images and toner images.

A charger 2, an LED array head 3, a developer 4, a transfer device 5, a cleaning device 6, a self-focusing lens array 9 (hereinafter referred to as 5LA), and the like are arranged around the photosensitive drum 1.

The charger 2 is used to uniformly charge the photosensitive drum 1 with positive or negative charges, and is usually called a charge controller. The LED array head 3 is an LED
7 are arranged in a row on the surface facing the photosensitive drum 1, and the 6LFD 7 corresponds to each printing dot. A drive circuit (not shown) is arranged in the LED array head 3, and this drives each LED.
7 are independently controlled to light up.

Between the LED array head 3 and the surface of the photosensitive drum facing it, a converging 5LA9 is connected to the LED array head 3.
When the blinking operation of the LED 7 is repeated in order in accordance with the image information for each line, the blinking information of the light is supplied to the photosensitive drum 1 one line at a time. Become. At this time, the photosensitive drum 1 is rotating in the direction of the arrow. As a result, the surface of the photosensitive drum 1 is moving in the sub-scanning direction, and L
When the ED array head 3 is driven, an electrostatic latent image is formed on the drum surface using a rask scan method.

The developing device 4 develops the electrostatic latent image thus formed with toner to create a toner image. The created toner image is transferred onto printing paper 8 by the action of transfer device 5. The transfer device 5 is a corona discharge device like the charger 2, and is usually called a transfer colodron. The printing paper 8 has been fed from a paper supply tray (not shown), and after the toner image is transferred, it passes through a fixing section (not shown), where the image is fixed. The print paper that has been fixed is discharged onto a paper discharge tray, which is also not shown.

In such an LED printer, if there is variation in the amount of output light from each of the LEDs 7, the variation will directly appear as unevenness in the density of the image, degrading the image quality.

Therefore, conventionally, the output light amount of each LED 7 is measured in advance, and the measured value is stored in a read-only memory or the like, and each LE
When D7 is turned on, the contents of this read-only memory are read out and the light emitting time of each LED7 is adjusted, so that all LEDs
A method is used to correct the amount of output light to be constant.

[Problems to be Solved by the Invention] However, the LEDs 7 used in the LED printer are arranged at a pitch of 16/1 mrn so as to have a resolution of 16 dots per III, for example. Also, 5L
As shown in the cross-sectional perspective view of FIG. 4, A9 is constructed such that two rows of convergent rod lenses 10 having a diameter of about 1 mm are stacked in two rows so that light passes through them in the longitudinal direction, and are held by a support frame 11. There is. Therefore, as the accuracy of the light amount correction of the LEDs 7 as described above improves, the unevenness of the light O due to the misalignment of the optical axes between each LED 7 and each convergent rod lens 10 becomes noticeable. That is, each LED 7 and the rod lens 10
Let Δy be the deviation of the optical axis with respect to the rod lens 10, as Δy increases, the unevenness of the light mother on the light receiving side increases as shown in FIG. For this reason, even if the output light amount of the LED itself can be adjusted to a constant value, light display unevenness occurs on the light receiving side due to the deviation of the optical axis, and there is a problem in that unevenness in image shading cannot be resolved as it is.

An object of the present invention is to provide a light zero correction method for a light emitting diode array that can eliminate unevenness in the amount of light on the light receiving side even if the optical axis is misaligned.

[Means for Solving the Problems] According to the present invention, the amount of light output from each light emitting diode is measured through an SLA, and the light emitting time during lighting is adjusted based on the measured value.

[Function] Even if there is a deviation in the optical axis from the SLA, the light emitting time of each light emitting diode is adjusted so that there is no excess or deficiency in the light display due to the deviation, and the light is corrected to a constant light Φ as a whole. Ru.

[Example] FIG. 1 is a flowchart showing the procedure of the light amount correction circuit of the present invention, and each LED 7 is lit with the IED array head 3 and SLA 9 integrated before being incorporated into the LE printer. , 5LA9 is measured for each LED. The measured value is then stored in a read-only memory. Thereafter, the ED array head 3 and 5LA9 are incorporated into the LED printer, and the read-only memory is also incorporated into the light amount correction circuit.

Therefore, when a lighting command is input to each LED 7 when actually recording an image, the output light measurement value of that LED 7 is read out from the read-only memory, and the light emission time is adjusted based on that measurement value. , the amount of input light on the photosensitive drum surface on the light receiving side is corrected to be constant.

FIG. 2 is an explanatory diagram showing a comparison between the unevenness of light amount due to the correction method of the present invention and the unevenness of light display due to the conventional correction method. It can be seen that while the (luminous intensity x light emission time) changes significantly, the correction method of the present invention reduces the amount to less than 1/3 of that of the conventional method.

Note that in the above embodiment, only the case where the LED array and SLA are used is explained.
Needless to say, the present invention can be applied to all devices that use a set of light sources.

[Effects of the Invention] As explained above, in the present invention, the output light amount of the light emitting diode is measured through the convergent lens, and the light emitting time is adjusted based on the measured value, so that the light emitting diode and the convergent lens are Even if there is a misalignment of the optical axis, the unevenness of the amount of light on the light receiving side can be significantly reduced, and the image quality of an LED printer or the like can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing the correction procedure of the present invention, Fig. 2 is an explanatory diagram showing a comparison between the correction results according to the present invention and the conventional correction results, Fig. 3 is a schematic configuration diagram of an LED printer, and Fig. 4 is FIG. 5 is a cross-sectional perspective view showing the structure of the convergent lens, and is an explanatory diagram showing uneven light display due to optical axis misalignment between the convergent lens and the light emitting diode. 3...LED array head, 7...LED, 9...
・Self-focusing lens array, 10...Convergent Rondo lens. Applicant's agent Takahisa Kimura (Xl 5.um) Tsukino r-cho Figure 5

Claims (1)

[Claims] The amount of light output from each light emitting diode in a light emitting diode array in which multiple light emitting diodes are arranged in a row is measured in advance, and based on the measured value, the amount of light output when each light emitting diode is lit is constant. In a light intensity correction method for a light emitting diode array that corrects the light emission time and guides the light to the light receiving side via a lens array placed in front of the light emission direction, the output light intensity of each light emitting diode is measured through the lens array, and based on the measured value. A light intensity correction method for a light emitting diode array, which is characterized by adjusting the light emitting time when the light is turned on.