JPH0791950A - Photodetecting sensor - Google Patents

Abstract

PURPOSE:To obtain a sensor which is small with an angle of visibility expanded by utilizing a refraction phenomenon of light generated on the interface of a medium varied in the density. CONSTITUTION:Light 6 made incident from a slit 2 refracts toward the normal on the interface of a medium 1 and reaches one side of a photodetector 3 in close contact with the bottom part of a medium 1 to generate electrical signal. The signal is passed through a signal processing circuit 15 to drive a motor for driving so that a correction is made to turn the normal of a sensor to a light source. When the normal of the sensor falls on the same straight line as the light source, the incident light travels straight without refraction from the slit 2 to generate an electrical signal of equivalence in the photodetector 3 on both sides when it is cast on the top alone of a light shielding wall 4 provided on the interface of the elements 3 or when the thickness of the light shielding water 4 is smaller as compared with the width of the slit 2. The signal is synchronized with a circuit 15 to be down to zero and the motor will not rotate. Thus, the movement of the light source is always tracked thereby making it possible to hold the direction of the sensor in front of the light source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving sensor used for tracking a light source moving in space.

[0002]

2. Description of the Related Art Sunlight is an essential light source that feeds all living things on the earth. Therefore, the desire to stably incorporate this sunlight indoors was remarkable throughout the east and west of ancient times. Sunlight is much larger than artificial light,
It also includes all wavelengths of light, from ultraviolet to infrared, and its energy is inexpensive. Generally, in order to effectively use the sunlight, it is not convenient to use a light source that moves in the sky. For example, when sunlight is taken indoors and used for lighting, or in a laboratory that uses ultraviolet rays contained in sunlight, or for healthy lighting, indoor cultivation of vegetables, etc., leave the sunlight completely stationary. Need to be kept. The sun is a light source that moves from the east to the west at a rate of 15 degrees per hour when viewed from the ground due to the rotation of the earth. The maximum altitude of the day also changes daily depending on the season. Therefore, in order to track the sunlight, it is necessary to decompose the position of the sun into a horizontal azimuth angle and a height elevation angle, and to detect each with a sensor. It is necessary to keep the sun facing the detector all day long, and the light receiving sensor is used for this purpose.

A cross-sectional perspective view of a conventional light receiving sensor is shown in FIG.
The operation will be described below. The light incident from the slit 2 opened on the upper surface of the space closed by the light shield, the sunlight hits one point on the opposite side of the slit, that is, the plurality of light receiving elements 3 arranged side by side on the bottom surface of the box. A signal such as a change in electromotive force or electric resistance is given to the light receiving element in that portion. This signal passes through a signal processing circuit to activate a driving device for controlling the direction of the light receiving sensor to correct the direction.

However, in such a conventional light receiving sensor, the inside of the box closed by the light shield is a space, and since the medium is the same as the outside to the light, the light goes straight through the slit 2. For that purpose, the base has a limited length from one end to the other of the light receiving elements arranged in a line at the bottom of the inside, and the angle of the apex of an isosceles triangle having the slit 2 on the top as the apex is the operating range of the incident light. , That is, the viewing angle, which cannot be so large due to the structure. There was a problem that the sensor would not work if this angle was exceeded.

[0005]

However, when tracking the sunlight in a direction completely different from the direction of the light receiving sensor, or when capturing a light source appearing in the nighttime space, the viewing angle should be as small as possible. This is where a wide light receiving sensor is desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly accurate light receiving sensor which dramatically expands the operating range of the light receiving sensor, that is, the viewing angle.

[0007]

In order to solve the above-mentioned problems, the present invention utilizes a phenomenon in which light travels in different media and changes its traveling direction to be refracted, whereby the size is reduced and the viewing angle is dramatically expanded. It was possible to provide the received light sensor.

A typical one is shown in FIG. A medium 1 is, for example, transparent glass or transparent resin. The shape is a rectangular parallelepiped, and a slit 2 is formed at the center of the upper surface, and the light receiving elements 3 are arranged at the center of the slit 2, that is, at the center of the extension of the normal of the surface of the slit 2 and at the front and rear in the direction perpendicular to the slit 2. The light receiving element is, for example, a CDS, a phototransistor, an image pickup element, or the like. Further, in order to reduce the mutual influence of the light receiving elements 3 as much as possible, a thin notch 4 is formed in the middle to a certain depth, and a black film or the like is inserted thereinto to provide a light shielding wall. As a result, the boundary between the light-receiving element 3 and the light-shielding wall 4 provided at a constant distance from the slit 2 on the surface of the light-receiving sensor is arranged on an extension of the normal line to the surface of the slit 2. . This light-receiving sensor is wholly completely shielded by the light shield 5 except the slit 2.

[0009]

[Operation] The operation of this light receiving sensor will be described. Output electric signals of a plurality of light receiving elements which detect light sources scattered in a wide range on a straight line or in a wide range of a two-dimensional space, for example, a plurality of light receiving elements are supplied to a signal processing circuit 15 to direct the light receiving sensor in the direction of the light source. On the other hand, the structure for activating the driving power to the position where it faces directly in front is as shown in FIG. 2 as described above. The medium 1 is not a space but a material such as glass or resin, which is a transparent material having a high density with respect to the space. A slit 2 is formed in the center of the surface of the medium 1, but when the light receiving element such as a phototransistor is small, a pinhole is used instead of the slit. Medium 1
Two light-receiving elements 3 are attached to the medium 1 in close contact with each other with the center of the bottom surface of the as a boundary. Further, the medium 1 is completely sealed except for the slit 2 by a light shield.

Because of the above-mentioned structure, when a light ray, for example, sunlight is incident from the normal direction of the slit, it goes straight in the medium without being bent, and two light receiving elements provided on the opposing surface are received. Illuminate the middle of the elements 3 to each other,
No detection signal is given to either of the light receiving elements, or there is no difference in the output of the same numerical value. Therefore, its combined output is zero. This is a state in which the light receiving sensor is correctly facing the light source. When the incident light from the slit is inclined with respect to the normal, when it enters the medium 1 having a high density with respect to the space, the light is refracted inward, that is, on the normal side according to the law of refraction. When the angle of incidence gradually increases and finally approaches 90 degrees, this is a viewing angle close to 180 degrees back and forth with respect to the slit, and the incident light is refracted at the boundary surface of the medium 1, but It does not spread beyond the critical angle of reflection. Therefore, if the light receiving element is arranged within the range of this critical angle, the incident light from the light source can cover near 180 degrees in front of the sensor. In other words, the viewing angle is 180
It can be extended to near degrees, which is a significant effect. In reality, the viewing angle is slightly hindered due to the thickness of the edge due to the structure of the slit. Further, if a thin cut is made in the middle of the light receiving elements on the normal line of the slit at a constant interval from the slit, and a light shielding curtain is inserted to form a light shielding wall, there is an effect of reducing light leakage between the light receiving elements.

[00011]

Embodiments of the present invention will be described with reference to FIGS. 2, 3, 5, and 6.
It is shown in FIG. 9, FIG. 10, FIG. 2 uses a transparent resin medium 1 and is easy to process and inexpensive. The effects are as described in the previous section,
A further supplementary explanation will be given. Incident light 6 entering from the slit 2 is refracted to the normal side at the boundary surface of the medium 1 as shown in the figure, and reaches one side of the light receiving element 3 arranged in close contact with the bottom of the medium 1. The light receiving element on the side receiving the light outputs an electric signal. Here, the electric signal passes through the signal processing circuit 15 and operates a driving motor connected thereto to correct the normal line of the light receiving sensor so as to face the light source. The internal structure of the signal processing circuit is omitted. When the incident light is incident from the side opposite to the normal line, an electric signal is induced in the other light receiving element, which is the opposite of the former case. This is the same as operating the drive motor connected through the signal processing circuit in the opposite direction to the former,
Correct the light receiving sensor so that its normal line is on the same line as the light source. When the normal line of the light receiving sensor is on the same straight line as the light source, the incident light from the light source goes straight through without being refracted from the slit and irradiates only the top of the light shielding wall formed at the boundary of the light receiving element, or light is shielded. When the thickness of the wall is narrower than the width of the slit 2, an equal amount of electric signal is generated in the light receiving elements 3 on both sides across the light shielding wall. This is combined in the signal processing circuit and the signal becomes zero, and the drive motor does not rotate in either direction. By always tracking the movement of the light source in this way, the direction of the light receiving sensor can always be kept in a position directly facing the light source.

The embodiment shown in FIG. 3 will be described. Making a light shielding wall by making a notch at a certain depth in the center of an integrated medium is likely to be damaged during the work, and making the notch of the light shielding wall sufficiently narrow has some drawbacks in the work. or,
When the medium is resin, it is relatively soft, and the slits of the incident light window are exposed to the outside, so that they are easily damaged. In addition, when the slits are installed, or when the slits are formed on an extremely thin metal plate, there is a risk that the adhesive may enter and the slits may be polluted. Also, when the slit is formed by a metal spraying technique or the like, when the medium is resin, there is a problem due to the working temperature. The one shown in FIG. 3 is made in consideration of this point. The two pieces of the cut medium 1 and the medium 10 made of glass are bonded and integrated as shown in the figure. Since the light shielding film can be sandwiched between the mutual adhesive surfaces of the resin medium 1, a sufficiently thin light shielding wall can be formed. Since the slits formed on the surface are also glass surfaces, they are not easily scratched and can be easily cleaned even if they become dirty. Further, since a sufficiently thin slit can be formed by a metal spraying technique or the like, a very sensitive light receiving sensor can be obtained by waiting for the thin light shielding wall 4.

FIG. 5 shows the medium 1 of FIG. 3 which is not a rectangular parallelepiped but is inclined outward. Slit 2
When the angle of incidence of the incident light from is increased, the component reflected from the boundary surface of the slit 2 increases, and the refracted component gradually weakens. The distance up to 3 can be shortened to compensate for the attenuated amount.

FIG. 6 shows a combination of four mediums 1 having orthogonal slits. At each boundary surface of the medium 1, light-receiving elements are optically insulated from each other with a light-shielding film interposed therebetween as in the above-described examples. This can track the azimuth and elevation with a single light-receiving sensor when tracking a spatial light source, for example, sunlight.

The structure shown in FIG. 9 has the same structure as that of FIG. 6, but the medium 1 is inclined outward to compensate for the attenuation of refracted light when the incident angle is large. The one shown in FIG. 10 is made by embedding a phototransistor in the medium 1 and can be made extremely small. In FIG. 11, the one shown in FIG. 2, FIG. 3, FIG. 5, etc. is cut into two from the center of the width of the slit, and each slit is symmetrically provided on only one side. This is used as a set of two toy eyes.

[00016]

As described above in detail, in the present invention, the viewing angle of the light receiving sensor can be dramatically expanded by utilizing the refraction of light generated at the boundary surface of the mediums having different densities.
Further, since the optical path of the incident light is not in space but in the medium, there is no concern about dew condensation in this part. In addition, it has many features such as being able to make the whole very small. Even if the outside of the slit is protected by thin glass or the like to prevent dust from adhering to the slit, its performance is not affected at all.

[Brief description of drawings]

FIG. 1 is a side sectional view of a conventional light receiving sensor.

FIG. 2 is a side sectional view of the present invention.

FIG. 3 is a side sectional view of another example of the present invention.

FIG. 4 is a plan view showing a slit of the present invention.

FIG. 5 is a side sectional view of another example of the present invention.

FIG. 6 shows a perspective view of only a medium portion of another example of the present invention.

FIG. 7 is a plan view showing the slit of FIG.

FIG. 8 is a plan view showing another example of the slit shown in FIG.

[Element 9] A perspective view is shown by a modification of the present invention shown in FIG.

FIG. 10 is a side sectional view of another example of the present invention.

FIG. 11 is a side sectional view of another example of the present invention.

12 is a plan view showing the slit of FIG. 11. FIG.

[Explanation of symbols]

 1 medium 2 slit 3 light receiving element 4 light shielding wall 5 light shield 6 incident light 7 incident angle 8 normal 10 medium such as hard transparent glass 15 signal processing circuit 16 space

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[Procedure amendment]

[Submission date] July 12, 1994

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side sectional view of a conventional light receiving sensor.

FIG. 2 is a side sectional view of the present invention.

FIG. 3 is a side sectional view of another example of the present invention.

FIG. 4 is a plan view showing a slit of the present invention.

FIG. 5 is a side sectional view of another example of the present invention.

FIG. 6 is a perspective view partially transparent view of another example of the present invention.

FIG. 7 is a plan view showing the slit of FIG.

FIG. 8 is a plan view showing another example of the slit shown in FIG.

FIG. 9 shows a perspective view of a modification of the invention shown in FIG.

FIG. 10 is a side sectional view of another example of the present invention.

FIG. 11 is a side sectional view of another example of the present invention.

12 is a plan view showing the slit of FIG. 11. FIG.

[Explanation of symbols] 1 is medium 2 is slit 3 is light receiving element 4 is light shielding wall 5 is light shielding object 6 is incident light 7 is incident angle 8 is normal line 10 is normal transparent glass etc. 15 is signal processing circuit 16 is space

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A light receiving sensor utilizing refraction of light generated at a boundary surface of media having different densities.