JPS6010964A - Driving method of led array light source - Google Patents

Abstract

PURPOSE:To improve the quality of a picture by shifting a P type area of an even number bit and a P type area of an odd number bit for a prescribed timing so as to drive them dividedly thereby avoiding a one-dot lateral line from being thick. CONSTITUTION:Only the P type areas 18(1),18(3),-18(2n-1) of an odd number bit are controlled for ON/OFF for a prescribed time by using a normal data and an LED extinguishing data is given all to the P type areas 18(2),18(4),-18(2n) of an even number bit at first. Then a photosensitive body 1 is moved by a required shift amount DELTAl, and the LED extinguishing data is given to all the P type areas 18(1),18(2),-18(2n) during the shift. After the photosensitive body 1 is moved by DELTAl, the normal data is given to the P type areas of the even number bit this time, the areas are subject to ON/OFF-control for a prescribed and the LED extinguishing data is given to the P type areas of the odd number bit. Thus, the irradiated position on the photosensitive body 1 is formed zigzag at each P area of the odd number bits and the even number bits and the luminance peak is coincident with the odd number bit and the even number bit.

Description

TECHNICAL FIELD The present invention relates to a method for driving an LED array light source for an optical writing head in a non-impact printer using an electrophotographic method.

Prior Art First, Figure 1 shows an overview of a printer that uses an LED array as a light source.After the surface of a photoreceptor drum 1 is uniformly charged by a charger 2, an optical writing device incorporating an LED play and an imaging element is used. 0N- of each LED element in head 3
An electrostatic latent image is formed on the photoreceptor drum 1 by optical switching by OFF. Thereafter, the latent image is visualized by the developing unit 4 and transferred by the transfer charger 7 onto the transfer paper 6 fed by the paper feed roller 5. After transfer, transfer paper 6
is sent to a fixing unit 9 by a conveyor belt 8 and fixed thereon, and is ejected by a paper ejecting roller 10. On the other hand, the surface of the photosensitive drum 1 is cleaned by the cleaning unit 11 in preparation for the next image formation.

Here, as shown in FIGS. 2 and 3, the optical writing head 3 consists of an LED array 12 and an imaging element, such as a SELFOC lens 13. The LED array chips are pasted in the center of this ceramic substrate 15 and the light emitting part 1 is arranged.
6 is common. As shown in FIG. 4, the structure of L and ED is that a P wall region 18 is provided on the surface layer of an N-type indirect transition type crystal 17, and an electrode 1 for conducting current is provided to this P wall region 18.
9 is provided. 20 is an insulating film, and 21 is an N-type electrode. When viewed from above, the P wall regions 18 are arranged in a row at predetermined intervals, as shown in FIG. 5, and the electrodes 19 for each P wall region 18 are arranged alternately on both sides of the row. . The reason why the electrodes 19 are arranged alternately is that the pitch of the P wall regions 18 is determined depending on the writing density, for example, 10.
This is because the pitch is very narrow at 100 μm pitch per book/wl.

When an LED array having such a pattern is made to emit light, the light emitting state is not uniform, and the luminance peak is distributed around the electrode 19 as shown in FIG. 6.

That is, FIG. 6 shows the luminance distribution in a direction perpendicular to the array direction in FIG. 5. In this case, when looking at the brightness distribution of the adjacent P wall region 18, since the electrode 19 is in the opposite direction, it becomes as shown by the dotted line in FIG. In this regard, even if the brightness peak shifts, there is no problem as long as the electrode 19 is arranged only on one side of the P wall region 18 rows.
As mentioned above, from the viewpoint of space, it is necessary to assume that the electrodes 19 are arranged alternately. For this reason, when all the P wall regions 18 arranged in the - column are turned on, the peaks of brightness appear in a staggered manner corresponding to the alternate arrangement of the electrodes 19. As a result, photoreceptor drum 1
The upper spot shape ends up being a spot shape extending in the sub-scanning direction (rotation direction of the photoreceptor drum 1).

Therefore, for example, if a negative-positive development process is adopted in which areas exposed to light are developed, the horizontal one-dot line will be thicker than the vertical line, resulting in a reduction in image quality.

Purpose The present invention has been made in view of the above points, and an object of the present invention is to provide an LED array light source driving method that can eliminate the thickening of one dot horizontal line and improve image quality. .

Configuration 1 First, the basic principle of the present invention will be explained based on FIGS. 7 to 9. The arrangement of the P-wall region 18 is the same as that in FIG. 5, but as shown in FIG.
g(1), 18(3),..., 18(2n 1), 18(2), 18(4),... in the P type region of even bits.
. , 18(2n) to distinguish them.

Therefore, first, the odd bit P wall regions 18(1), 18(
3), . . . , 18 (2n-1) are subjected to constant exposure time 0N10FF control using regular data. FIG. 8(,) shows the irradiation position on the photoreceptor 1 when all of these are turned on, and P(1), P(3), ..., P(2n 1) are the P-type regions 18(), respectively. 1), 18(3),..., 18(2
n-1). At this time, LED off data is given to all the even bit P wall regions 18(2), 18(4), . . . , 18(2n). Next, the time ΔQ/v for the photoreceptor 1 to move by the required shift amount of 68 minutes (however,
(2) is the linear velocity of the photoreceptor 1), all the P-type regions 18 (
1) to 18 (2n) are given LED off data. Here, the required shift amount ΔQ corresponds to the shift amount of the brightness peak in FIG.

After such a predetermined timing has elapsed, only the even-numbered bit P wall regions 18(2), 18(4), and 18(2n) are subjected to ON10FF control using regular data for a constant exposure time. At this time, the P wall regions 18(1), 18(3) of odd bits
, . . . , 18 (2n-1) are all given LED turn-off data. Therefore, as shown in FIG. 8(b), the irradiation position on the photoreceptor 1 is determined by P(
1), P(3), ..., P(2n-1) and those with even bits P(2), P(4), ..., P (2n)
and are staggered by Δα in the sub-scanning direction. Comparing this with FIG. 7, the direction of deviation is relatively
This is the direction without 9. In this case, since the shift amount ΔQ matches the shift amount of the brightness peak in FIG. 6, the brightness peaks of the odd bits and even bits overlap and match as shown in FIG. 9, and the brightness peak The lines PL will be aligned in a straight line. Therefore, the one-dot horizontal line does not become thicker in the sub-scanning direction. In other words, by dividing and driving the odd-numbered bit P-type region and the even-numbered bit P-type region with a predetermined timing shift, the luminance peaks can be aligned in a straight line as in the case where all the electrodes 19 for the P wall region 18 are arranged on one side. It can be modified as desired.

In this respect, the arrangement of the P wall region 18 itself is not in a straight line, but in an 8th straight line.
Although the objective can be achieved by structural improvement such as arranging in a staggered manner as shown in FIG. It's easy to do.

By the way, as shown in FIG. 10, the P wall region 18 consisting of 2n bits per line is divided into N blocks of B(1) to B(N), with each block having 2m bits, and each block is sequentially divided and driven. It is usually done. In this case, the P wall regions (1), (3), ..., (2ml) of odd bits of each block B(1) to B(N) are connected to the shift register driver 22 with a latch. , P wall regions (2), (4), . . . , (2m) of even bits of each block B(1) to B(N) may be controlled by connecting to a shift register driver 23 with a latch. . A NOR gate 24 is connected to the shift register driver 22, and the NOR gate 24 outputs odd bit data and even/odd select signals.
A signal inverted by the OT gate 25 is input.

On the other hand, the shift register driver 23 has a NOR gate 2
6 is connected, and even number bit data and even number/odd number select signals are input. As a result, first block B
After driving (1) with even bit data, block B (
2), B(3), . . . , B(N) are similarly driven with each even-numbered pitch l-data. During this period, all odd-numbered bit data are kept in the OFF state. 11th
In the figure, Tz (ON) indicates the exposure time of even bits of block B (1), and T1 (OFF) indicates the O of block B (1).
Indicates FF time. After driving with such even bit data, an odd number is selected, and after driving block B (1) with odd bit data, blocks B (2), B (3)
, . . . , B (N) are similarly driven with each odd bit data. While the odd bits are being driven with normal data in this way, all the odd bits are kept in the OFF state. T1' (ON) in FIG. 11 indicates the odd bit exposure time of block B(1). 1. Effects As mentioned above, the present invention is arranged so that each irradiation position is staggered so that the brightness peaks on the photoreceptor surface due to the P wall area of even number bits and the P wall area of odd number bits are on a straight line. Since the bits and odd-numbered bits are driven separately with a predetermined timing shift, the luminance peaks are aligned in a straight line while maintaining the structure in which the P wall regions are arranged in a line, eliminating the thickening of one dot horizontal line in the sub-scanning direction, and creating an image. It is something that can improve quality.

[Brief explanation of drawings]

Fig. 1 is a schematic side view of the printer, Fig. 2 is a front view of its optical writing head, Fig. 3 is a side view, Fig. 4 is a sectional view showing the LED structure, and Fig. 5 is a plan view showing a conventional example. , FIG. 6 is a brightness distribution characteristic diagram, FIG. 7 is a plan view showing an embodiment of the present invention, FIGS. 8(a) and (b) are front views showing the operation, FIG. 9 is a brightness distribution characteristic diagram, FIG. 10 is a circuit diagram, and FIG. 11 is a timing chart. 1...Photoreceptor, 18...P wall area, 19...electrode 1" Konn also 2 Figure 1 Ia Shigomo Kunji 5 Figure

Claims (1)

[Claims] P wall regions are arranged in a line in an N-type indirect transition type crystal, and this P
In an LED array light source that has electricity-conducting electrodes arranged alternately on both sides of a row of wall regions and moves relative to a photoreceptor,
The P-wall regions of even-numbered bits and the P-walls of odd-numbered bits are arranged so that the irradiation positions are staggered so that the brightness peaks on the photoreceptor surface due to the P-wall regions of even-numbered bits and the P-wall regions of odd-numbered bits are on a straight line. 1. A method for driving an LED array light source, characterized in that the regions are driven in a divided manner with a predetermined timing shift.