JPH07253316A - Angle detector - Google Patents

Abstract

PURPOSE:To enable the utilizing of the area of a photodetecting part effectively without using a part requiring high position accuracy by supporting two photodetectors with the equal photodetecting area at a fixed angle to determine an angle of a support to a light source based on each quantity of received light. CONSTITUTION:An angle detector 10 has two detectors 12 and 14 supported on adjacent side parts of a support (triangular column) 16. When an apex angle of the support is representd by 2alpha, the quantities of light received of the detectors 12 and 14 are proportional to a projection area when an angle between the apex angle oriented direction (equally divided line of apex angle) and a light source 18 is not zero. For example, the quantity of received light (output A) of the detector 14 is proportional to a cos (theta+alpha) and the quantity of received light (output B) of the detector 12 is proportional to a cos (theta-alpha). When an output difference D of the detectors 12 and 14 standardized by all outputs is given as (A-B)/A, theta=tan<-1> (D/Tanalpha) is obtained. Thus, the angle theta of the tip of the apparatus 10 in the direction to the light source 18 is determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical angle detecting device.

[0002]

2. Description of the Related Art An angle detecting device is used in combination with two angle detecting devices to detect a position coordinate (two-dimensional position coordinate) of an article (light source), a rotation angle of an article (pivoting angle of the article), and the like. The detected angles (positional coordinates and rotation angles) are used, for example, as information input to an input device of a computer. Various types of angle detecting devices used in this way have been proposed so far. For example, as an angle detection device having a movable part, a device that rotates a cylindrical body having a slit and a light receiving element in the cylindrical body detects that the slit matches the direction of the light source, and detects the angle from the position. In some cases, the angle of the light receiving element is changed so that the amount of light received from the light source is maximized, and the angle is continuously detected from the position showing the maximum amount of received light. As the angle detecting device having no movable part, for example, a position detecting device (PSD: position sensitive device) is used, and
There is an angle detection device in which a lens is arranged in front of the SD, light from the light source is condensed by the lens, and the angle of the light source is detected from the position where the light spot enters the PSD.

Since the former angle detecting device has a movable part, it has a complicated structure, is prone to failure, and generally takes a long time for detection. The latter angle detecting device does not have the problems of the former, but the PSD
Are relatively expensive, and lenses have to be used.

In order to solve the above-mentioned problems of the angle detecting device, the applicant of the present invention has previously filed a two-part photodetector (two-part pin photo diode) (for one-dimensional angle detection) and a four-part photo detector (four-part pin photo). It has been proposed to use a diode) (for two-dimensional angle detection) for angle detection. The two-divided photodetector has two light-receiving portions arranged side by side, and each light-receiving portion electrically detects the amount of incident light, and the four-divided photodetector has four light-receiving portions vertically and horizontally. In addition, each light receiving portion electrically detects the amount of incident light independently. In order to detect the angle, a diaphragm (aperture) is placed in front of these photodetectors, and the incident light always enters each light receiving part within the predetermined angle range to be detected, and at the same time, from each light receiving part. It is necessary to set the aperture so that it is not the only one. The angle calculation is performed based on the difference in the amount of light detected in each light receiving portion (for example, when standardizing when using two photodetectors, the ratio of the difference between the amounts of light and the sum of the amounts of light). In the two-division or four-division photodetector, it has been found that the light amount difference (ratio of the light amount difference and the light amount sum) is almost proportional to the incident angle, and the angle is calculated from this relation.

On the other hand, instead of arranging a diaphragm opening in front of the photodetector, a light-shielding plate is vertically arranged between the light receiving portions of the photodetector, and the light source enters the photodetector based on the amount of light received by each light receiving portion. An angle detection device for detecting the incident angle of the incident light has also been proposed as a prior application by the present applicant.

[0006]

The angle detecting device using these photodetectors has an advantage that it is not necessary to use a lens and the photodetector is relatively inexpensive as compared with the PSD, but the photodetector is used as a diaphragm. There is a problem that a high positional accuracy is required when the opening of or is provided, and the cost is increased. Further, in the angle detection device provided with the aperture for the diaphragm, the diameter of the diaphragm (when the diaphragm is circular) has to be relatively large in order to obtain a sufficient amount of light, and as a result, the photodetector also has a larger area for receiving light. I had to use the one with. For example, in the case of a two-divided photodetector, a photodetector area that is approximately twice the aperture area is required, and in the case of a four-divided photodetector, approximately four times the photodetector area is required. There is a problem that the unit price of the photodetector having a large light receiving portion naturally increases.

Therefore, it is an object of the present invention to provide an angle detecting device using a photodetector which can effectively utilize the area of a light receiving portion without the need of using a component requiring high positional accuracy. is there.

[0008]

In order to achieve the above-mentioned object, the present invention provides at least two photodetectors having the same light receiving area for receiving light from a light source, and a support for supporting each photodetector at an angle. The angle detecting device is adopted, which has a body and a computing means for computing an angle at which the support body tilts with respect to the light source based on the amount of light received by each of the photodetectors.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of an angle detecting device according to a first embodiment of the present invention, and FIG. 2 is a plan view thereof. 1 and 2, the angle detection device 10 includes two photodetectors 12 and 14 and a triangular prism 16 that supports the two photodetectors 12 and 14 on adjacent side portions.

Next, the detection principle of the angle detection device 10 of the present invention will be described with reference to FIG. In FIG. 2, the apex angle of the support of the triangular prism sandwiched by the photodetectors 12 and 14 is 2α, and the direction in which the apex angle is directed (that is, the bisector of the side portion to which the photodetectors 12 and 14 are fixed and the light source 18). When the angle formed is θ, when θ is zero, the light from the light source is evenly incident on both photodetectors 12 and 14, so the amount of light received by each photodetector 12 and 14 is equal, but θ is not zero. Sometimes, a difference occurs in the amount of received light, and the amount of received light is proportional to the projected area of each photodetector 12, 14 with respect to the light source 18.
That is, in the case of FIG. 2, the amount of light received by the photodetector 14, and thus its output, is proportional to COS (θ + α),
The amount of light received by the photodetector 12, and thus its output, is proportional to COS (θ−α).

Now, let the output of one photodetector 14 be A and the output of the other photodetector 12 be B,
If the output difference of the photodetectors 12 and 14 normalized with respect to all outputs is D {= (A−B) / (A + B)}, the following formula is established. D = {COS (θ−α) −COS (θ + α)} / {COS (θ−α) + COS (θ + α)} = {− 2 · SIN (2θ / 2) · SIN (−2α /
2)} / {2 ・ COS (2θ / 2) ・ COS (-2α / 2)} = 2 ・ SINθ ・ SINα / 2 ・ COSθ ・ COSα = TANα ・ TANθ Therefore, θ = TAN ^-1 (D / TANα)

In this way, the angle formed by the tip direction of the detector with respect to the light source can be obtained from the differential output normalized with respect to all outputs. In particular, when the apex angle of the triangular prism is 90 °, θ = T
AN ⁻¹ (D), which can be obtained by a simple relational expression.

(Embodiment 2) In Embodiment 1 using two photodetectors, angle detection is effective in a range of up to ± 45 ° (when the apex angle of the triangular prism is 90 °), but it will be described below. If one photodetector is added as in the second embodiment, the angle detection range can be expanded to ± 90 °. 3 is a perspective view of an angle detection device according to a second embodiment of the present invention, and FIG. 4 is a plan view thereof.

In FIGS. 3 and 4, the angle detection device 20 is shown.
Consists of three photodetectors 22, 24, 26 and a rectangular parallelepiped 28 that supports these three photodetectors 22, 24, 26 on adjacent portions (two of which are on opposite sides), respectively. In this configuration, for example, the photodetectors 22 and 24 can detect an angle range from 0 ° to 90 °, and the photodetectors 24 and 26 can detect −90 °.
The angle range from 0 to 0 ° can be detected and combined ± 90 °
The angle range of can be detected. Of course, similar detection can be performed by attaching a photodetector to each of the trapezoidal surfaces as well as the upright solid. However, in that case, the detection range becomes shorter than ± 90 °.

(Third Embodiment) In the second embodiment, three photodetectors are fixed to a rectangular parallelepiped and an angle range of ± 90 ° can be detected, but this is one-dimensional detection. In the third embodiment, two-dimensional angle detection can be detected by adding two more photodetectors. FIG. 5 is a perspective view of the angle detection device according to the third embodiment of the present invention.

In FIG. 5, the angle detection device 30 includes three photo detectors 32, 34, 36, 38, 40, and
These five photo detectors 32, 34, 36, 3
A rectangular parallelepiped 42 for supporting 8 and 40 in adjacent portions (two pairs of photodetectors are on opposite sides)
Consists of. In this configuration, for example, the photo detector 3
Two-dimensional angle detection can be performed by using the output difference between 2 and 34 and the output difference between the photodetectors 32 and 36.

(Embodiment 4) In Embodiment 4, Embodiment 3
The two-dimensional angle detection can be performed similarly to. Figure 6
[Fig. 8] is a perspective view showing an angle detection device according to a fourth embodiment of the present invention. In FIG. 6, the angle detection device 50 is composed of four photodetectors 52, 54, 56 and 58 and a quadrangular pyramid 60 that supports these four photodetectors 52, 54, 56 and 58 on adjacent sides. With this configuration, for example, two-dimensional angle detection can be performed by using the output difference between the photo detectors 52 and 56 and the output difference between the photo detectors 54 and 58.

(Fifth Embodiment) A fifth embodiment is a modification of the first embodiment. Instead of the triangular prism-shaped support in the first embodiment,
It uses a support having an inwardly bent surface. Figure 7
[Fig. 8] is a perspective view showing an angle detection device according to a fifth embodiment of the present invention. In FIG. 7, the angle detection device 70 includes two photodetectors 72 and 74 and a support body 76 that supports the two photodetectors 72 and 74 on the inwardly folded surfaces, respectively.

[0020]

As described above, according to the present invention,
An angle detection device using a photodetector that can effectively use the area of the light receiving portion can be obtained without using a component that requires high positional accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view of an angle detection device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the angle detection device according to the first embodiment.

FIG. 3 is a perspective view of an angle detection device according to a second embodiment of the present invention.

FIG. 4 is a plan view of an angle detection device according to a second embodiment.

FIG. 5 is a perspective view of an angle detection device according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing an angle detection device according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing an angle detection device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 10 Angle Detection Device 12, 14 Photo Detector 16 Support 18 Light Source

Claims (8)

[Claims] 1. A photodetector for receiving light from a light source, the photodetector having an equal light receiving area, a support for supporting each photodetector at an angle, and the support based on the amount of light received by each of the photodetectors. An angle detecting device, comprising: a calculating means for calculating an angle of inclination with respect to the light source. 2. The angle detection device according to claim 1,
The angle detection device, wherein the support has a triangular prism shape, and each of the photodetectors is fixed to a portion corresponding to one side of the support. 3. The angle detection device according to claim 2,
The vertical angle of the support of the triangular prism is 2α, the angle between the bisector of the side where each photodetector is fixed and the light source is θ, and the outputs of the photodetector are A and B, respectively.
And the output difference of the photodetector normalized by the total output of the photodetector is D {= (A−B) / (A + B)}, the angle θ can be obtained by θ = TAN ⁻¹ (D / TANα). Characteristic angle detection device. 4. The angle detection device according to claim 2,
An angle detecting device, wherein an angle formed by a fixed portion of each of the photodetectors is a right angle. 5. The angle detection device according to claim 1,
The support is a rectangular parallelepiped, and the photodetector is fixed to at least three surfaces of the rectangular parallelepiped.
An angle detection device characterized in that the first surface and the second surface of the two surfaces are adjacent to each other, and the third surface is adjacent to the first surface and opposite to the second surface. 6. The angle detection device according to claim 5,
An angle detection device in which the photodetectors are fixed to five surfaces of the rectangular parallelepiped. 7. The angle detection device according to claim 1,
The angle detector, wherein the support is a quadrangular pyramid, and four photodetectors are fixed to respective side portions of the quadrangular pyramid. 8. The angle detection device according to claim 1,
An angle detecting device, wherein the support has two surfaces bent inward, and a photodetector is fixed to the two surfaces.