JPH0121804Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light emitting device used in an optical printer.

[Conventional technology]

FIG. 4 is a perspective view showing an example of the arrangement of light emitting devices in an optical printer, and in the figure, 1 indicates the light emitting devices;
2a and 2b are focusing fiber lenses, and 3 is a photosensitive drum.

The light-emitting device 1 has a light-emitting element array, which will be described later. Since it is difficult to obtain a long array length with strict precision in this light-emitting element array, in an optical printer, a plurality of light-emitting devices 1 are arranged in two rows in a staggered manner. The light from the light emitting element array of each light emitting device 1 in row A is imaged on the photosensitive drum 3 via the focusing fiber lens 2a, and the light from the light emitting element array of each light emitting device 1 in row B is focused. A desired array length is obtained by forming an image on the photosensitive drum 3 via the optical fiber lens 2b, and aligning the lights of the light emitting element arrays of the light emitting devices 1 in the A and B rows in a line on the photosensitive drum 3. I'm trying to get it.

Note that l is the imaging area of the light emitting element array of each light emitting device 1. In addition, focusing fiber lens 2
Figures a and 2b are each formed by arranging several rows of converging single fibers at equal pitches and cutting the fibers so as to obtain the same magnification.

FIG. 5a is a perspective view of a single conventional light emitting device used as described above, and FIG. 5b is a plan view of the light emitting element array. This light emitting element array 5 is formed by monolithic technology using gallium arsenide phosphide (GaAsP) as a base material, and has light emitting elements 6 ₁ to 6 _o arranged in a line on the surface. ing.

This light emitting element array 5 is not shown in the figure because when the light emitting elements 6 ₁ to 6 _o are integrated at a high density, it is difficult to take out all the electrodes 7 ₁ to 7 _o from one side of the element row. Take out every other element alternately from both sides.

In other words, each electrode 7 ₁ of the light emitting elements 6 ₁ , 6 ₃ . . . 6 _o-1 ,
7 ₃ . . . 7 _o-1 are taken out from one _side of the element array, and each electrode _{7 2 , 7 4 .}

These electrodes 7 ₁ , 7 _{3 .} . . 7 _o-1 are connected to thick film conductors 8 ₁ to 8 _o formed on the base substrate 4 via bonding wires 9 ₁ to 9 _o .

Note that the light emitting elements 6 ₁ to 6 _o are usually positive electrodes, and negative electrodes are formed on the back surface of the light emitting element array 5.

[The problem that the idea aims to solve]

By the way, in each light-emitting element of the light-emitting element array 5 in this type of light-emitting device, the light emission center position, that is, the part showing the peak value of light intensity, is usually biased toward each electrode, and therefore, the conventional light-emitting device described above When the electrodes 7 1 - _{7 o} of the light emitting elements 6 ₁ - 6 _o are taken out alternately on both sides of the element row as in the device, the x-coordinate when the light intensity reaches the maximum is as shown in Fig. 3. It will not match.

In other words, in the group of light emitting elements 6 ₁ , 6 _{3 .} . . 6 _o-1 and the group of light emitting elements 6 _{2 ,} 6 ₄ . As a result, the light emitted from the light emitting elements ₆₁ to _6o is not imaged in a straight line on the photosensitive drum 3, but is formed in a zigzag pattern as shown by point 6a in FIG. .

[Means to solve problems]

The present invention provides a light-emitting device having a structure in which a plurality of light-emitting elements are arranged in a line and the electrodes of each light-emitting element are taken out alternately on both sides of the element row, in which the shape of adjacent light-emitting elements is is characterized in that one side on the electrode side is narrow, one side on the opposite side from the electrode is wide, and the middle part is constricted, so that the light emitting center positions of each light emitting element are aligned almost on the same line. shall be.

[Effect]

According to the above configuration, the shapes of adjacent light emitting elements are such that one side on the electrode side is narrow, one side on the opposite side from the electrode is wide, and the middle part is constricted. The light emission center positions are aligned approximately on the same line, and images can be formed on the same line on the photosensitive drum.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In the following description, the same parts as those in the above-mentioned prior art will be described using the same reference numerals.

FIG. 1 is a plan view. In the figure, 4 is a base substrate, 5 is a light emitting element array mounted on this base substrate 4, 6 ₁ to 6 _o are light emitting elements, and 7 ₁ to 7 _o are each light emitting element 6. ₁ to 6 _o electrode, and this electrode 7 ₁ to
7 _o are taken out alternately on both sides of the element row every other element.

8 ₁ to 8 _o are thick film conductors formed on the base substrate 4, and 9 ₁ to 9 _o are bonding wires connecting the electrodes 7 ₁ to 7 _o and the thick film conductors 8 ₁ to 8 _o , respectively. .

The reason why the light emitting elements 6 ₁ to 6 _o do not form images on the same straight line on the photosensitive drum 3 in the conventional light emitting device is because
This is due to the fact that the x coordinates at which the light intensity of each of the light emitting elements 6 ₁ to 6 _o reaches its maximum are shifted as described above.

Therefore, in this embodiment, as shown in the figure, the shape of the light emitting elements 6 ₁ to 6 _o is such that one side of the electrodes 7 ₁ to 7 _o is narrow in width, the opposite side is wide, and the middle part is constricted. The shape is similar to that of the original.

Figure 2 shows the light intensity function I(x), the light emitting element area function S(x), and the luminescence amount function T(x).
This shows a function of I(x)S(x), and according to this, each x coordinate when the light intensity of each light emitting element 6 ₁ to 6 _o becomes maximum coincides. In other words, the light emission center positions are arranged substantially on the same line, and the light from the light emitting elements 6 ₁ to 6 _o can be imaged on the same line on the photosensitive drum 3.

Here, the structure of the light emitting element array 5 will be explained with reference to the cross-sectional view shown in FIG.

A GaAsP epitaxial wafer is used as the substrate wafer 10, and a SiO ₂ film 11 is coated on this substrate wafer 10.
Selective thermal diffusion of Zn is performed through the light emitting device 6,
6 ₁ to 6 _o are formed. In addition, the p-side electrodes 7, 7 ₁
~7 Al for _o , Au-Ge-Ni for n-side electrode 12
This can be achieved by using .

[Effect of idea]

According to the present invention described in detail above, in a light emitting device having a light emitting element array having a structure in which a plurality of light emitting elements are arranged in a line and the electrodes of each light emitting element are taken out alternately on both sides of the element row, Adjacent light emitting elements are shaped so that one side on the electrode side is narrow, one side on the opposite side from the electrode is wide, and the middle part is constricted, so that the light emitting center position of each light emitting element is almost the same. They are lined up in a line, which has the effect that images can be formed on the same line on the photosensitive drum.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the present invention, Fig. 2 is a diagram showing functions of light intensity, light emitting area, and light emitting amount, Fig. 3 is a cross-sectional view of a light emitting element array, and Fig. 4 is an optical printer. FIG. 5 is a perspective view showing an example of arrangement of light emitting devices in FIG.
FIG. 6 is a perspective view, b is a plan view of a light emitting element array, and FIG. 6 is a diagram showing a light intensity distribution function of a conventional light emitting device. DESCRIPTION OF SYMBOLS 1... Light emitting device, 2a, 2b... Focusing fiber lens, 3... Photosensitive drum, 4... Base substrate, 5... Light emitting element array, 6... Light emitting element, 7
...Electrode, 8...Thick film conductor.

Claims (1)

[Claims for Utility Model Registration] In a light-emitting device having a light-emitting element array having a structure in which a plurality of light-emitting elements are arranged in a line and the electrodes of each light-emitting element are taken out alternately on both sides of the element row, adjacent The shape of each light emitting element is such that one side on the electrode side is narrow, one side on the opposite side from the electrode is wide, and the middle part is constricted, so that the light emitting center position of each light emitting element is aligned almost on the same line. A light emitting device characterized by: