JPS622675A - Light emitting diode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light emitting diode, and more particularly to a light emitting diode with improved luminous efficiency.

(Prior Art) A light emitting diode is a semiconductor element that emits light from the PN junction by applying a DC voltage to the PN junction. Since they are much smaller in size than ordinary lamps, they have been widely used in recent years as light sources for displaying various information.

FIG. 6 is a diagram showing an example of the configuration of a conventional light emitting diode chip (hereinafter referred to as an LED chip). In the figure, 1 is a chip with each side Q and a size of about 3 mm, 2 is an anode electrode, and 3 is a cathode electrode. The cathode electrode 3 is
Usually, the entire bottom surface of the chip 1 can be formed as an electrode, and the anode electrode 2 is usually attached to the center of the light emitting surface 10 by wire boarding. L configured like this
When a DC voltage is applied between the electrodes 2 and 3 of the ED chip, light is emitted from the entire chip. As it is, it is not commercially viable, so the entire chip 1 is covered with a transparent mold, and lead wires for the anode and cathode are provided to form a light emitting diode (LED) as a commercial product.

(Problems to be Solved by the Invention) When a chip as shown in FIG. Part of the light emission is blocked by the electrode 2, resulting in poor light emission efficiency.

This light shielding by the electrode 2 reduces the illuminance and causes uneven illumination. In recent years, scanners that read image information using line image sensors have been developed, but in such scanners, uniformity of illumination in one direction poses a problem. When an array incorporating LED chips as light emitting elements is used as a light emitting means, in the conventional LED array, the electrode is formed approximately in the middle of the light emitting surface, so that uneven illuminance occurs in one direction. This illuminance unevenness could not be eliminated even if the shape of the electrode was made smaller.

The present invention has been made in view of these points, and
The purpose is to realize a light emitting diode that does not cause unevenness in illuminance on the light emitting surface at least in the direction of the light emitting diode.

(Means for Solving the Problems) The present invention, which solves the above problems, is characterized in that the electrodes attached to the light emitting surface are provided offset from the center of the chip.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

The embodiment shown in the figure shows only the light emitting surface, and the other shapes are the same as the conventional example shown in FIG.

(a) shows an example in which one anode electrode ti (hereinafter simply referred to as an electrode) is provided, and (a) shows an example in which two electrodes are provided. Note that the shaded areas in the figure indicate the electrodes. (stomach)
In the case of the embodiment shown in (B), the electrode 11 is formed at one corner of the light emitting surface 10, and in the case of the embodiment shown in (B), the electrode 11 is formed at one corner of the light emitting surface 10.
2.13 are formed at two opposing corners of the light emitting surface 10, respectively.

When the electrodes are provided offset from the center of the light emitting surface 10 in this way, the central portion of the light emitting surface is not blocked by the electrodes. Furthermore, light is not blocked in the diagonal direction (A-A' direction) in the figure. Therefore, by arranging LEDs or LED chips in the diagonal direction, it is possible to obtain illumination light with uniform brightness at least in this diagonal direction, and the length of the uniform illumination can also be freely set. Can be done. Note that when an LED array is configured by arranging LED chips in one row, all the LED chips may be arranged on a common base electrode as the cathode electrode portion, and only the anode electrode may be attached to each LED independently. Therefore, according to the present invention, a light source suitable for use in illuminating a line-type image sensor can be obtained.

FIG. 2 is a diagram showing a method for manufacturing a light emitting diode according to the present invention. Portions L1 to L12 surrounded by rectangles in the figure each constitute an ED chip.

The shaded area in the figure is the electric bridge section. A rectangular electrode portion as shown in the figure is formed at the boundary of each LED chip, and
When divided and cut out, each LED chip has a shape as shown in FIG. 1(A). According to this manufacturing method, the number of electrodes to be attached can be reduced to 1/4 of the conventional one, and the area of the electrodes can be increased, making it easier to manufacture LED chips and significantly reducing the number of manufacturing steps. .

In the above description, the shape of the electrode portion is rectangular, but it is not limited to this, and may be any shape as long as it is biaxially symmetrical. However, it is necessary to consider the shade area. FIG. 3 is a diagram showing various shapes of the electrode portion. (A) is a circle, (B) is a polygon, and (C) is a quadrilateral.

Any type of biaxially symmetrical type may be used.

In the above description of the manufacturing method, an example is taken in which an electrode is placed at one corner of the LED chip, but an LED as shown in FIG. 1 (b) having electrodes at two diagonally opposite corners,
It is also possible to manufacture chips.

In this case, as shown in FIG. 4, the number of electrodes is doubled compared to the manufacturing method shown in FIG. Therefore, the number of electrodes is reduced to 1/2 of the conventional case. Further, in the above explanation, the case where the electrodes are provided at any of the four corners of the UED chip is taken as an example, but the present invention is not limited to this, and the electrodes may be formed offset from the center of the light emitting surface. For example, it can be in any position. For example, L with a shape as shown in Figure 5.
It may be an ED chip. The shaded area in the figure is the electrode.

In either case, since light is not blocked in two diagonal directions, the degree of freedom in design increases when manufacturing an LED array, which is advantageous in manufacturing.

(Effects of the Invention) As explained in detail above, according to the present invention, the electrode is provided at a position shifted from the center of the light emitting surface (secondly, since the central part of the light emitting surface is not blocked from light, a uniform According to the present invention, by arranging the LED chips in one row without providing R1'i in at least one diagonal direction, it is possible to realize a light emitting diode with uniform illuminance in the row direction. It is possible to realize a light source for illumination, and it is suitable for use in a line-type image sensor.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a method for manufacturing a light emitting diode according to the present invention, FIG. 3 is a diagram showing various shapes of electrode parts, and FIG. 5 is a diagram showing another method of manufacturing a light emitting diode according to the present invention, FIG. 5 is a diagram showing various shapes of electrodes, and FIG. 6 is a diagram showing an example of a conventional structure of an LED chip. 1... Chip 2... Anode electrode 3...
・Cathode electrode 10... Light emitting surface 11-13...
Electrode L1~l-+? ...ED chip patent applicant Konishi Rokushaoku Kogyo Co., Ltd. Agent Patent attorney Fuji Ijima 1 person 1st figure

Claims (2)

[Claims] (1) A light emitting diode characterized in that the electrodes attached to the light emitting surface are arranged offset from the center of the chip. (2) The light emitting diode according to claim 1, wherein no electrode is provided in at least one diagonal direction of the chip.