JPS6323375A - Light emitting diode - Google Patents

Abstract

PURPOSE:To manufacture light emitting diode optimum for various applications enabling its optical beam to be controlled by the shape of junction part of both semiconductor layers of the light emitting diode by a method wherein the junction part of semiconductor layers is exposed at one end of light emitting diode while the junction part is shaped into a specified type. CONSTITUTION:A junction part B taken into specified shape is exposed to one end of a light emitting diode to control the shape of optical beams emitted from the light emitting diode by the shape of junction part. In other words, the optical beams being emitted from a recouple of both semiconductor layers 30, 32, the junction part B can be taken into e.g. a slit shape so that the light emitting diode may externally emit optical beams corresponding to the slit shape. The shape of junction part B can be taken into arbitrary type such as a round, square, slit, etc., according to the applications of light emitting diode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light emitting diode, and particularly to a light emitting diode having an improved structure for regulating irradiated light from the light emitting diode into a predetermined luminous flux υ1.

[Prior Art] Light-emitting diodes are well known as electrical-optical conversion elements.
It is widely used as various indicators, photoelectric sensors, etc.

This type of light-emitting diode generally includes a diode that emits visible light, which is mainly used in a display device, or an infrared diode, which is mainly used as a photocoupler, photoinluctor, or other photoelectric sensor.
Many types of light emitting diodes are used depending on various uses.

FIG. 4 shows an example of a conventional semiconductor junction type light emitting diode, in which two types of semiconductor layers 10.1 with different polarities are used.
2 is arranged in the fi layer, and the desired light emitting action is performed at the junction between both semiconductor layers 10 and 12.

At J3 in FIG. 4, the first semiconductor layer 10 is made of a P-type GaAS semiconductor, and the second semiconductor layer 12 is made of N! 1! Ga
Both As semiconductors have a square thin layer shape.

Electrode metals 11514.16 are provided on both end faces of both semiconductor layers 10.12 by vapor deposition or other methods, and high voltage side lead wires 18.16 are provided on both metal fii 4.16, respectively. The low voltage side lead wires 20 are connected to each other by bonding. In the figure, both metal films 14 and 16 each consist of a gold vapor deposited film.

According to the conventional device shown in FIG. 4, both lead wires 18.2
The holes and electrons injected from the two-handed conductor layer 10.
They recombine at the junction of 12, and at this time, a light emission phenomenon occurs due to the electron excitation energy.

In conventional equipment, metal 1! In order to effectively inject holes on the A14 side, the metal film is formed in a substantially cross shape, and the light emitted from the a3f to the junction described above is emitted from the end surface of the first semiconductor layer 10 in the direction of the arrow. The light is irradiated upward as shown at A. Therefore, desired display or photoelectric detection can be performed using this irradiation light.

[Problems to be Solved by the Invention] However, in the conventional device described above, since the light emitted from the light emitting diode is irradiated to the outside from the end face of the semiconductor layer 10, this light flux is relatively easily diffused and narrowed down sharply. There was a problem in that it was difficult to obtain a light beam. Conventionally, the light emitted from the light emitting diode is diffused only by being focused into a light beam having a desired diameter by a guide or collimator lens provided in the optical path that guides the light. No consideration was given to light diffusion.

In particular, it is desirable for light-emitting diodes used in displays etc. to widen the visual field of display light through appropriate light diffusion, and from the standpoint that diffusion as a light source is necessary, conventional methods have been used to regulate the luminous flux of irradiated light. It wasn't a problem.

However, photoelectric sensors basically require a sharply focused light beam;
It is conceivable to provide a guide hole in the base substrate that fixes the light emitting diode to regulate the light flux outside the light emitting diode, or to obtain a sufficiently focused light beam using a collimator lens or the like. I was able to do that.

However, in recent years, as light-emitting diodes have come to be used as extremely high-precision photoelectric sensors, a problem has arisen in that the desired resolution cannot be obtained by the light beam focusing effect applied externally to the light-emitting diodes. In addition, in order to obtain sufficiently high resolution, the external connection device for the light emitting diode, such as a collimator lens, must be configured as a lens with a sufficiently large focal length, and the photoelectric sensor itself must be configured as a lens with a sufficiently large focal length. There was a problem with increasing the size.

In FIG. 5, a photoelectric linear encoder is shown as -(4) of such a precision photoelectric sensor.

In the figure, the linear encoder includes a measurement grating 22 and a reference grating 24, and both path elements 22 and 24 have a configuration in which a light transmitting part and a light shielding part are aligned at a predetermined grating bit.

Therefore, by moving either one of the two track elements 22.2/I according to the length to be measured, it becomes possible to measure the length while the two track elements are moving relative to each other.

In order to electrically detect the relative shift of the grating, the above-mentioned light emitting diode 100 is provided on one side of the pair 22 and 24, and the emitted light is focused into a light beam by the collimator lens 26. , Ryojiko 22.24
Transparent.

On the other hand, a light-receiving element 26 such as a phototransistor is provided on the opposite side of both the terminals 22 and 24, and electrically detects the change in brightness of the transmitted light and outputs an electrical signal to the outside via a preamplifier 28. It can be supplied to a processing circuit.

FIG. 6 shows the output signal waveform of the preamplifier 28, in which the electrical output signal has a substantially sinusoidal shape as shown in response to the relative displacement of the pair of terminals 22 and 24. Although not shown in the figure, an external processing circuit counts this sine wave signal, thereby making it possible to perform measurement with an accuracy determined by the grating pitch and the number of divisions in the processing circuit.

The output signal of the waveform t in Figure 6 is the DC component and the AC valve AC.
In such a linear encoder, the ratio of both signal components is a predetermined value, usually I'
1. It is desired that it is above OJ, i.e. AC/DC
It is known that a good measurement effect cannot be obtained unless the AC component ratio is greater than or equal to 1.0.

It is known that such a ratio depends on the lattice spacing G between the two pairs of 22 and 24 elements, and characteristic 2 in FIG.
00 indicates the AC/DC ratio with respect to the grating spacing G, and as is clear from the figure, in the past, it was understood that the grating spacing G had to be extremely narrow; for example, the grating pitch was set to 10 μm/10 μm Tf 1 degree. In this case, the distance between both terminals 22 and 24 must also be 10 μm or less, which means that both terminals 22 and 24 must be held and slidably supported extremely precisely, requiring a great deal of effort in processing and assembling the parts. I needed it. The inventor of the present invention confirmed that such a lattice spacing G is related to the diameter of the light beam irradiated to both the beams 22 and 24. It was concluded that the lattice spacing G can be set with more margin.

In addition, in order to narrow down the light beam, the focal length F of the collimator lens 26 is related, as is well known, and as shown in FIG. Although it is focused,
At this time, the diffusion angle θ of the light beam is expressed as θ-D/F. In order to reduce the diffusion angle θ and make a sufficiently long parallel ray 1 It is understood that the focal length F needs to be increased.

However, as mentioned above, the diameter of the irradiation surface of the conventional light emitting diode 100 is determined by the outer shape of the semiconductor layer forming the light emitting diode 100, and as a result, in the conventional method, the focal length fiF needs to be sufficiently increased. , there was a problem that the irradiation unit for the grating pair 22 and 24 became large.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an improved light emitting diode that can regulate the irradiated light in the light emitting diode itself and obtain irradiated light that is less diffused and can be focused easily. It is in.

[Means for Solving the Problems] In order to achieve the above object, the present invention exposes the junction of semiconductor layers of different polarities that perform the light emitting function of the light emitting diode on one end face of the light emitting diode, and By setting the shape of the part to a predetermined shape, the shape of the light beam irradiated from the light emitting diode is regulated by the shape of the joint part.

[Example code] Preferred embodiments of the present invention will be described below based on the drawings.

1 and 2 show preferred embodiments of the light emitting diode according to the present invention.

The light emitting diode according to the embodiment has a substantially rectangular substrate shape, the first semiconductor layer 30 is made of N-type GaAS, and the second semiconductor layer 32 is formed by forming a layer on the first semiconductor layer 30. Junction is arranged. The second semiconductor layer 32 is of P type G.
The P-type semiconductor layer is made of aAS and is doped with, for example, IZn. Therefore, it is understood that the two-handed conductors 111M30.32 become semiconductors having mutually different polarities, and that light is emitted at the junction B thereof.

According to the combination of semiconductor layers in Example J3, near-infrared light is mainly emitted, but of course, in the present invention, GaP or (GaAI)As may be used as these semiconductors in addition to the above-mentioned GaAs. is also possible,
Emit visible light if necessary.

Further, in the present invention, the two-handed conductor layers 30, 32 can be arranged with their polarities, that is, P type and N type, reversed.

Both hands 4) The end faces of the body layer 30.32 are provided with metal films 34 and 36 for electrodes, and according to the embodiment, these metal films 34 and 36 for electrodes are formed by vapor deposition of gold. However, if necessary, these electrode metal films 34 and 36 can be formed on the end faces of the semiconductor layers 30 and 32 by any other method such as spackling.

A low-voltage side lead wire 38 and a high-voltage side lead wire 40 are bonded to the metal films 34 and 36 for both electrodes, respectively, and electrons and holes are injected into each semiconductor ff30.32 via both electrodes. .

Therefore, the holes and electrons injected in this way recombine at the joint surfaces of the two-handed conductor layers 30 and 32, and at this time, the electron excitation energy causes light emission at a predetermined frequency, and in the embodiment, near-infrared light is emitted. emits light.

Of course, in the embodiment, since the electrode metal film 36 is electrically connected only to the second semiconductor layer 32, an insulating film 42 is formed on the upper surface of the second semiconductor layer 32. 5i3N4 (silicon nitride) or the like is used.

A characteristic feature of the present invention is that the junction B is exposed on one end surface of the light emitting diode and has a predetermined shape, and the shape of the junction B regulates the shape of the light beam emitted from the light emitting diode. That is what we are doing.

That is, the light beam is generated by recombination at the joint B between the two-handed conductor layers 30 and 32, and by forming the joint B into a slit shape, for example, as shown in the figure,
It becomes possible to emit a light beam corresponding to the shape of this slit to the outside from the light emitting diode.

In the present invention, the shape of the junction B can be any shape, and can be round, square, slit, or any other shape depending on the use of the light emitting diode.

The light emitting diode shown in FIGS. 1 and 2 is formed for a photoelectric linear encoder, and for this purpose, it is preferable that the new surface of the light beam is in the shape of an elongated slit, and the shape of the junction B also emits light. It is formed thinly along the end face of the diode.

In the example, the outer shape of the semiconductor layer forming the light emitting diode has a planar dimension of about 200 x 600 μm, and on this end face, the shape of the junction B in the example has a slit width W of 50 μm and a slit width of 400 μm. It is formed.

FIG. 3 shows a photoelectric linear encoder in which the light emitting diode according to the present invention described above is used, and has an encoder structure similar to the conventional device shown in FIG. 5 described above. The measurement grating 22 and the reference grating 24, which move relative to each other according to the length of the object to be measured, form a grating pair, and the light beam passes through optical slits formed in both of the tracers 22 and 24. At times, changes in the brightness of this light beam are electrically detected to measure a predetermined amount of relative movement.

The light beam is formed by a light emitting diode 100 according to the present invention and a collimator lens 26 that focuses the light beam, while the light receiver is composed of a light receiving element 26 such as a first transistor, and the detected electric signal is sent to a preamplifier 28. is supplied to an external processing circuit.

As is clear from FIG. 3, the shape of the junction of the light-emitting diode 100 according to the invention has a slit shape, and the slits are arranged in alignment with the optical gratings of the double strands 22, 24.

Therefore, a short slit width corresponds to the scale movement direction X, which affects the resolution of the encoder. As a result, as is clear from the diffusion angle θ in FIG. The diameter is regulated to be extremely small in the present invention, and in the example, since the slit width of the joint portion is approximately 5011 m, it is limited to 1/8 of the conventional width, and as a result, , significantly reduce the diffusion angle θ, or use the collimator lens 2.
It becomes possible to shorten the focal length gap of 6.

Therefore, as shown in FIG. 3, by using the present invention, it is possible to significantly reduce the size of the light emitter of the linear encoder.

At J3 in Fig. 3, the joint portion of the embodiment has a sufficiently long length in the slit longitudinal direction Y, and in the case of a linear encoder, it does not affect the resolution in the Y direction at all, but is rather sufficient. In order to secure a sufficient amount of light M, it is necessary to have a sufficiently large emission length in the longitudinal direction Y of the slit, and the embodiment shown in FIG. This is extremely useful for providing a sharply focused light beam in the direction of scale movement X.

be.

As described above, by sufficiently confining the light beam from the light emitter according to the present invention, for example, in the photoelectric linear encoder shown in FIG.
There is an advantage that the gap G between the two positions can be set relatively large.

In FIG. 7 mentioned above, the ratio AC/DC of the output signal waveform to the grating bit G is shown, but the characteristic in this example is shown by 202, and the grating interval G is set to 50μ.
It is clear that even if the width is expanded to about m, a sufficiently practical output signal of 4q can be obtained.

As described above, according to the present invention, the diameter or shape of the light beam was not considered at all inside the light emitting diode, and the light beam was regulated by a light shielding plate or a guide provided outside the light emitting diode. On the other hand, according to the present invention, by regulating the light beam itself emitted from the light emitting diode, it is possible to miniaturize the device and improve the luminous efficiency. Since the beam Jl system uses the shape of the junction between both semiconductor layers, a light emitting diode that can obtain a good light beam can be produced extremely easily without increasing the manufacturing process or the like.

[Effects of the Invention] As explained above, according to the present invention, a light beam can be regulated using the shape of the junction between both semiconductor layers of a light emitting diode, and it is easy to create a light emitting diode that is optimal for various uses. It has the advantage of being 1q.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a preferred embodiment of the light emitting diode according to the present invention, Fig. 2 is a sectional view taken along the line ■-■ of the light emitting diode shown in Fig. 1, and Fig. 3 is the light emitting diode shown in Figs. An explanatory diagram showing a state in which a diode is used as a photoelectric linear encoder, Fig. 4 is a perspective view showing an example of a conventional light emitting diode, and Fig. 5 is a photoelectric linear encoder using a light emitting diode in the conventional device shown in Fig. 4. Figure 6 is a diagram of the output signal waveform of the linear encoder shown in Figure 5, Figure 7 is a characteristic diagram of the grating pitch and AC/DC signal ratio of the output signal in the photoelectric linear encoder, and Figure 8 is a diagram of the output signal ratio of the light emitting diode. FIG. 3 is an optical characteristic diagram of a collimator lens that focuses a light beam. 30.32... Semiconductor layer B... Junction.

Claims (1)

[Claims] (1) Semiconductor layers of different polarities are arranged in a bonded manner, metal films for electrodes are formed on the end faces of both semiconductor layers, and light emission is performed at the junction of both semiconductor layers by the injection current supplied from the electrodes. The diode is characterized in that the junction between the two semiconductor layers is exposed on one end face of the light emitting diode, and the junction has a predetermined shape, so that the light irradiated by the light emitting diode is limited by the shape of the junction. light emitting diode.