JP2007147557A - Angle detecting sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detecting sensor capable of detecting angles of gradient correctly and stably, even under the conditions where the angle detecting sensor repeats attitude variations, while attempting reduction in size and weight. <P>SOLUTION: The angle detecting sensor consists of a base, a casing, a light receiving element, and a light-shielding body. The light receiving element is prepared at the base. The light-shielding body is supported by the inner-wall bearing face of a cylindrical form of the casing with adjustable displacement so as to shield the light receiving element by the light-shielding body. The light receiving element has a circular acceptance region, and the acceptance region includes four accepting planes by quadrisecting the area. According to the tilting of the angle detecting sensor, the light-shielding body is displaced by gravity. If the light-shielding body is displaced, the amount of light received of each acceptance plane also varies and each acceptance plane outputs analog signals corresponding to each amount of light received. The analog signals, output from each acceptance plane, are processed by a signal processing circuit to detect tilting angles of the angle detecting sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an angle detection sensor that is attached to an optical device such as a camera and is suitable for detecting its posture.

  Conventionally, as this kind of angle detection sensor, one using an optical sensor is known. This angle detection sensor has a property in which a light shielding object such as a sphere is arranged between a light source and an optical sensor, and the light shielding object displaced by the action of the posture of the device and the action of gravity blocks light input to the optical sensor. Is used to detect the attitude of the device (Patent Documents 1 and 2).

In addition, as an angle detection sensor using an optical sensor, a fan-shaped reflecting plate that rotates about an axis in accordance with a change in the posture of the device and gravity reflects the light from the light source toward the optical sensor. A device that detects the posture of the camera is also known (Patent Document 3).
Japanese Patent Laid-Open No. 9-292219 Japanese Patent Laid-Open No. 11-63981 JP 11-37739 A

  However, since the conventional angle detection sensor has a large space in which the light shielding object can be displaced, the light shielding object is susceptible to not only gravity but also acceleration due to frequent posture changes of the device. That is, the acceleration caused by frequent changes in the posture of the device, together with the size of the space where the light shield can be displaced, has a non-negligible effect on the position of the light shield. As a result, the signal output from the optical sensor includes an error, and an accurate inclination angle cannot be detected.

  In addition, an angle detection sensor using a sphere or the like requires an internal space composed of, for example, a hemispherical surface for moving the sphere or the like, and it has been difficult to reduce the size.

  Furthermore, an angle detection sensor using a reflector can detect only a rough angle by itself, and it is necessary to use a plurality of angle detection sensors in order to detect an accurate angle.

  The present invention has been made to solve these problems at the same time, and an object of the present invention is to obtain a small and lightweight angle detection sensor capable of stably detecting an accurate posture.

  An angle detection sensor according to the present invention includes a light receiving element having a light receiving area composed of a plurality of light receiving surfaces, a light blocking body that can block the light receiving area and that can be displaced by its own weight, and a cylindrical shape that supports the light blocking body in a displaceable manner. And a casing having an inner wall supporting surface, wherein at least one of the plurality of light receiving surfaces is shielded by a light shielding body that is displaced along the inner wall supporting surface, and an inclination angle around a cylindrical axis of the casing is detected. To do.

  The light shielding body is preferably cylindrical, and it is even better if the cylindrical shape has an axial length shorter than the radius. Thereby, the size of the angle detection sensor can be reduced. The light shield may be a sphere.

  The light shield has a first end face facing the light receiving element and a second end face opposite to the light receiving element, and the shapes of the first end face and the second end face are convex curved surfaces. preferable. By reducing the contact area between the casing and the light shielding body, friction can be reduced, and accurate tilt angle measurement can be performed.

  Further, the light shield is a cylindrical body that is slidably contacted with the inner wall support surface of the casing over the entire circumference and is rotatably supported with respect to the central axis of the inner wall support surface of the casing. The cylindrical through-hole having a shorter diameter may have a shape having a central axis parallel to the central axis of the light shielding body and opening near the outer edge of the light shielding body. Stable inclination angle detection can be performed by reducing unnecessary displacement of the light shield.

  The light receiving area is preferably circular, and the light receiving surface is preferably divided into four equal parts by two orthogonal straight lines.

  The inner wall surface facing the light receiving element side of the casing may be a concave curved surface, and the storage chamber forming the inner wall support surface may be filled with a liquid that transmits light. This is to reduce the friction between the casing and the light shielding body.

  The angle detection sensor is preferably provided with a light source that illuminates the light receiving area, and the light source may be a thin light emitter.

  The angle detection sensor uses an amplifier that amplifies an analog signal output from the light receiving area, an A / D converter that converts the analog signal output from the amplifier into digital data, and data output from the A / D converter. And a circuit for calculating the tilt angle of the light receiving element.

  According to the present invention, accurate posture detection can be stably performed even under a situation in which the device repeats posture changes, and since the configuration is simple, it is possible to reduce the cost, size, and weight.

  Embodiments of an angle detection sensor according to the present invention will be described below with reference to the accompanying drawings.

  1 and 2 show a first embodiment, FIG. 1 is a front view of an angle detection sensor, and FIG. 2 is a side view of the angle detection sensor.

  The angle detection sensor 10 includes a base 11, a casing 20, a light receiving element (for example, a photodiode) 30, and a light shielding body 40. The base 11 has a square base front surface 12, and a transparent casing 20 having a cylindrical inner wall support surface 21 and a flat inner wall surface 22 is attached to the base front surface 12. A square recess 13 for installing the light receiving element 30 is provided at the center of the base front surface 12. A square light-receiving element 30 is fitted in the recess 13. The depression 13 has such a depth that the installed light receiving element 30 does not protrude from the base front surface 12. The light shielding body 40 is disposed on the cylindrical inner wall support surface 21 of the casing 20 so as to be displaceable so as to shield the light receiving element 30.

  A circular light receiving region 31 is formed on the light receiving element 30 which is square. The light receiving region 31 includes four light receiving surfaces 30a, 30b, 30c, and 30d. The light receiving surfaces 30a, 30b, 30c, and 30d are formed by a straight line that passes through the center of the light receiving element 30 and is parallel to any side of the light receiving element 30, and a straight line that passes through the center of the light receiving element 30 and is orthogonal to the straight line. The light receiving region 31 is a quadrant obtained by dividing the light receiving region 31 into quarters.

  The light receiving surfaces 30a, 30b, 30c, and 30d output analog signals when irradiated with light. The analog signal changes according to the area where the light receiving surfaces 30a, 30b, 30c, and 30d receive light.

  The light shield 40 has a cylindrical shape. The light shield 40 is slidably provided on a cylindrical inner wall support surface 21 formed between the base front surface 12 and the casing 20 so as to shield the light receiving region 31. The diameter of the light shielding body 40 is preferably approximately ½ of the diagonal length of the light receiving element 30. However, the diameter of the light shield 40 may be appropriately changed as long as the tilt angle can be detected.

  When the casing 20 is disposed on the base 11 as described above, the light shielding body is limited in displacement in the direction perpendicular to the respective light receiving surfaces, and is displaced only on a plane on the light receiving element 30. Since the displacement in the vertical direction destabilizes the amount of light received at each light receiving surface, the tilt angle can be stably measured by limiting this.

  In the present embodiment, the angle detection sensor 10 is installed such that the top is vertically upward in FIG. When the angle detection sensor 10 is tilted around the cylindrical axis of the casing 20, the light blocking body 40 moves to the lowest position in the figure of the casing 20 due to gravity. As a result, the region of the light receiving region 31 that is exposed to light changes, and the analog signals output from the light receiving surfaces 30a, 30b, 30c, and 30d vary. By measuring analog signals output from the light receiving surfaces 30a, 30b, 30c, and 30d and selecting the light receiving surface that outputs the lowest voltage, the inclination angle of the angle detection sensor 10 can be detected in steps of about 90 degrees. it can.

  The light source 50 may be provided inside or outside the angle detection sensor 10. The light source 50 projects light to the light receiving area 31. Thereby, even if external light does not reach the angle detection sensor, the inclination of the angle detection sensor 10 can be detected. As the light source, for example, an LED is suitable.

  As described above, according to the first embodiment, it is possible to stably detect the tilt angle of the angle detection sensor 10 in increments of 90 degrees. Furthermore, since the inner wall support surface 21 of the casing 20 is cylindrical, a small angle detection sensor 10 can be obtained.

  A second embodiment will be described with reference to FIG. FIG. 3 is a block diagram of the angle detection sensor 10 including a signal processing circuit 60 that processes an analog signal from each light receiving surface.

  In the present embodiment, a signal processing circuit 60 is added to the first embodiment. Other structural requirements are the same as those in the first embodiment.

  The signal processing circuit 60 includes an amplifier 61, an A / D converter 62, and an arithmetic circuit 63, and has a function of calculating an inclination angle by processing an analog signal output from each light receiving surface. The analog signals output from the respective light receiving surfaces are amplified by the amplifiers 61, respectively. The analog signal amplified by the amplifier 61 is converted into digital data by an A / D converter 62 that performs digital conversion. The data output from the A / D converter 62 is processed by the arithmetic circuit 63 to detect the tilt angle of the angle detection sensor 10.

The arithmetic circuit 63 performs the calculation according to the equation (1). Va is a light-receiving surface 30a, Vb is 30b, Vc is 30c, and Vd is a voltage value output from 30d. θ is the calculated tilt angle of the angle detection sensor 10 obtained by calculation. The calculation inclination angle θ of the angle detection sensor 10 is obtained by calculating the output voltage value from each light receiving surface using the following equation.
θ = −tan ⁻¹ ((Vd−Vb) / (Va−Vc)) + 135 (1)

  When the signal processing circuit 60 is provided inside the angle detection sensor 10, the tilt angle can be detected without providing a separate signal processing circuit outside the angle detection sensor 10. If the signal processing circuit 60 is provided outside the angle detection sensor 10, the angle detection sensor 10 can be downsized.

  As described above, according to the second embodiment, the tilt angle can be detected with higher accuracy than the detection angle by the angle detection sensor 10 in the first embodiment, for example, with an accuracy of about 2.5 degrees pitch. . Note that third to seventh embodiments described later also include a signal processing circuit 60.

  A third embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view of an angle detection sensor in which the light shield has a substantially elliptical cross section.

  In the present embodiment, the shape of the light shielding body in the first embodiment is changed to have a substantially elliptical cross-sectional shape. Other structural requirements are the same as those in the first embodiment.

  The light shield 40 a has a first end face 41 facing the light receiving element 30 and a second end face 42 opposite to the light receiving element 30. The first end surface 41 is a convex curved surface with respect to the base front surface 12, and the second end surface 42 is a convex curved surface with respect to the inner wall surface 22. It is preferable that the diameter of the light shield 40 a is approximately ½ of the diagonal length of the light receiving element 30. However, the diameter of the cross section parallel to the light receiving region 31 of the light blocking body 40a may be appropriately changed as long as the inclination angle can be detected.

  As described above, in the third embodiment, the surfaces 41 and 42 of the light shielding body 40a are convex curved surfaces, so that the friction generated between the light shielding body 40a and the casing 20 or the base 11 is the first embodiment. Therefore, the angle can be detected quickly and accurately.

  A fourth embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view of an angle detection sensor in which the light shield has a circular through hole 43. FIG. 6 is a front view of the light shield 40b. FIG. 7 is a perspective cross-sectional view of an angle detection sensor in which the light shield 40b has a circular through hole 43. As shown in FIG.

  In the present embodiment, the shape of the light shielding body in the first embodiment is changed to a cylindrical shape having a through hole. Other structural requirements are the same as those in the first embodiment.

  The light shielding body 40 b is a columnar body that is slidably contacted with the cylindrical inner wall support surface 21 of the casing 20 over the entire circumference and is rotatably arranged with respect to the central axis of the cylindrical inner wall support surface 21. A circular through hole 43 having a diameter shorter than the radius of the cylindrical body is formed in the light shielding body 40b. The central axis of the through hole 43 is parallel to the central axis of the light shield 40b. The through hole 43 opens near the outer edge of the light blocking body 40b. However, the diameter of the through hole 43 may be appropriately changed as long as the inclination angle can be detected.

  Since the portion where the through hole 43 is located is relatively light in weight in the entire light shielding body 40b, even if the casing 20 is inclined around the cylindrical axis, it is always located on the upper side in the drawing due to gravity. The light receiving surface where the through hole 43 is located receives light, and the light receiving surface where it is not located is shielded. As a result, the amount of light received by each light receiving surface changes, an analog signal corresponding to the amount of received light is output, and the angle is detected.

  As described above, in the fourth embodiment, since the light blocking body 40b is in contact with the inner wall support surface 21 of the casing 20 over the entire circumference, it does not fluctuate abnormally with respect to the rapid movement of the angle detection sensor. . Thereby, the analog signal output from each light-receiving surface is stabilized, and the measurement accuracy is improved as compared with the first embodiment.

  A fifth embodiment will be described with reference to FIG. FIG. 8 is a cross-sectional view of an angle detection sensor in which the light shield is spherical.

  In the present embodiment, the shape of the light shield in the first embodiment is changed. Other structural requirements are the same as those in the first embodiment.

  In the present embodiment, the light shielding body in the first embodiment is formed into a spherical shape. The diameter of the light shield 40c is preferably approximately ½ of the diagonal length of the light receiving element 30. However, the diameter of the light blocking body 40c may be changed as appropriate as long as the inclination angle can be detected. If the light shielding body 40c is spherical, the friction generated between the light shielding body 40c and the casing 20 or the base portion 11 is reduced, and quick and accurate angle detection is possible.

  As described above, by making the light shielding body 40c spherical, the friction generated between the light shielding body 40c and the casing 20 or the base portion 11 is smaller than that of the first embodiment, and quick and accurate angle detection is possible. It becomes.

  A sixth embodiment will be described with reference to FIG. FIG. 9 is a cross-sectional view of an angle detection sensor in which the inside of the casing 20 is configured by a curved surface 22a.

  In the first embodiment, the inner wall surface 22a of the casing 20 has a concave shape with respect to the base front surface 12 in the first embodiment. Other structural requirements are the same as those in the first embodiment.

  By making the inner wall surface 22a into a concave shape, the friction generated between the light blocking body 40 and the inner wall surface 22a is less than in the first embodiment in which the inner wall surface 22 is flat, and quick and accurate angle detection is possible. It becomes possible.

  A seventh embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view of an angle detection sensor including a thin light source.

  In this embodiment, the light source 50 is a thin light source in the first embodiment. Other structural requirements are the same as those in the first embodiment.

  The axial length of the light source 50a in the present embodiment is shorter than the thickness of the casing 20 and the base portion 11 plus the axial length. By providing this thin light source 50a, the angle detection sensor can be miniaturized. As the light source 50a, for example, a thin LED or a surface light emitting element is suitable.

  As described above, according to the seventh embodiment, it is possible to obtain a smaller angle detection sensor than the first embodiment, which can detect the tilt angle without providing a light source outside.

  In any of the first to seventh embodiments, the number of light receiving surfaces may be two. In this case, the light receiving surface is a bisector that bisects the light receiving region 31 with respect to the area by a straight line that passes through the center of the light receiving element 30 and is parallel to any side of the light receiving element 30. As a result, the angle detection sensor can be detected in a range of 0 to 180 degrees while the configuration of the angle detection sensor is made simpler than that of the first embodiment. Further, the light receiving element 30 may not be square, and may be circular, for example.

  In any of the first to seventh embodiments, the storage chamber formed by the casing 20 in which the light blocking body 40 is stored and the base 11 may be filled with a liquid that transmits light. As a result, friction between the light shield 40 and the casing 20 or the front surface 12 of the base is reduced, and abrupt displacement of the light shield 40 is reduced, thereby enabling stable angle detection.

  In any of the first to seventh embodiments, the angle detection sensor 10 may be installed with an inclination of 45 degrees to the left or right around the cylindrical axis of the casing 20. In this case, it can be used as a tilt sensor by providing a circuit for processing that the light receiving surface with the smallest output voltage is located at the lowest position. The circuit configuration is simpler than that of the signal processing circuit 60 in the second embodiment, and the angle detection sensor can be reduced in size, weight, and cost.

  FIG. 11 is a graph showing the relationship between the angle of inclination of the angle detection sensor and the voltage value of the analog signal output from each light receiving surface.

  The horizontal axis indicates the tilt angle of the angle detection sensor 10, and the vertical axis indicates the voltage value output from each light receiving surface. When the angle detection sensor 10 is tilted around the cylindrical axis of the casing 20, the light shielding position on the light receiving region 31 by the light shielding body 40 is changed, and the output voltage value from each light receiving surface is changed by the change in the light shielding position.

  FIG. 12 is a graph showing the relationship between the tilt angle of the angle detection sensor and the calculated tilt angle obtained by the calculation process.

  The horizontal axis represents the tilt angle of the angle detection sensor 10, and the vertical axis represents the value of the calculated tilt angle θ output from the calculation circuit. The inclination angle of the angle detection sensor 10 matches the calculated inclination angle θ, and accurate inclination angle detection is possible.

It is a front view of the angle detection sensor in 1st Embodiment. It is a side view of the angle detection sensor in a 1st embodiment. It is a block diagram of an angle detection sensor provided with the signal processing circuit which processes the analog signal from each light-receiving surface in 2nd Embodiment. It is sectional drawing of the angle detection sensor in which the light-shielding body has a substantially elliptical cross section in 3rd Embodiment. It is sectional drawing of the angle detection sensor in which the light-shielding body has a circular through-hole in 4th Embodiment. It is a front view of the light-shielding body in 4th Embodiment. It is a perspective sectional view of an angle detection sensor in which a light-shielding body has a circular through hole in a 4th embodiment. It is sectional drawing of the angle detection sensor whose light-shielding body is a sphere in 5th Embodiment. It is sectional drawing of the angle detection sensor with which the inside of a casing is comprised in a curved surface in 6th Embodiment. It is sectional drawing of an angle detection sensor provided with a thin light source in 7th Embodiment. It is the graph which showed the relationship between the inclination angle of an angle detection sensor, and the voltage value of the analog signal output from each light-receiving surface. It is the graph which showed the relationship between the inclination angle of an angle detection sensor, and the calculation inclination angle calculated | required by the calculation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Angle detection sensor 20 Casing 30 Light receiving element 31 Light receiving area 40 Light-shielding body 60 Signal processing circuit

Claims (13)

A light receiving element having a light receiving region composed of a plurality of light receiving surfaces;
A light-shielding body capable of shielding the light-receiving region and being displaceable by its own weight;
A casing having a cylindrical inner wall support surface for supporting the light-shielding body in a displaceable manner,
The light shielding body is displaced along the inner wall support surface according to an inclination angle around a cylindrical axis of the casing, whereby at least one of the plurality of light receiving surfaces is shielded to detect the inclination angle. An angle detection sensor.   The angle detection sensor according to claim 1, wherein the light shielding body has a cylindrical shape.   The angle detection sensor according to claim 2, wherein an axial length of the light shield is shorter than a radius.   The light shielding body has a first end face facing the light receiving element and a second end face opposite to the light receiving element, and the first and second end faces are convex curved surfaces. The angle detection sensor according to claim 1.   The light-shielding body is a cylindrical body that is in sliding contact with the inner wall support surface over the entire circumference and is rotatably supported with respect to the central axis of the inner wall support surface, and has a diameter shorter than the radius of the light-shielding body. 2. The angle detection sensor according to claim 1, wherein the cylindrical through-hole has a central axis parallel to the central axis of the light shielding body and opens closer to the outer edge of the light shielding body.   The angle detection sensor according to claim 1, wherein the light shield is a sphere.   The angle detection sensor according to claim 1, wherein the light receiving region is circular.   8. The angle detection sensor according to claim 7, wherein the light receiving surface is obtained by dividing the circular light receiving region into four equal parts by two orthogonal straight lines.   The angle detection sensor according to claim 1, wherein an inner wall surface of the casing facing the light receiving element is a concave curved surface.   The angle detection sensor according to claim 1, wherein a storage chamber that forms the inner wall support surface is filled with a liquid that transmits light.   The angle detection sensor according to claim 1, further comprising a light source that illuminates the light receiving region.   The angle detection sensor according to claim 11, wherein an axial length of the light source is shorter than a thickness obtained by adding an axial length of each of the casing and the base. An amplifier for amplifying an analog signal output from the light receiving region;
An A / D converter that converts an analog signal output from the amplifier into digital data;
The angle detection sensor according to claim 1, further comprising a circuit that calculates the tilt angle using data output from the A / D converter.

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