JP2009294151A - Inclination sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inclination sensor for accurately detecting the slope of a mounted member. <P>SOLUTION: Light emitted by a laser diode 110 is applied to a first collimator lens 130 via a beam splitter 120 and a reflective surface 121. The first collimator lens 130 converts incoming light into parallel light. The parallel light passes through an inclined mirror 140, the collimator lens 130, and the reflective surface 121, and is condensed on an imaging surface 151. A weight body 142 is rockable relative to the beam splitter 120 since the weight body 142 is connected to a frame body 144 via an elastic member 143. When this inclination sensor 100 is inclined relative to gravitation, a mirror surface 141 is not parallel to a surface of the beam splitter 120 mounted with the inclined mirror 140. Because of this, the optical path of light incident on the mirror surface 141 and that of reflected light are not the same. An inclination angle θ of the inclination sensor 100 is measured by measuring a difference between the optical paths on the imaging surface 151. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tilt sensor that detects the tilt of an attached member.

2. Description of the Related Art Conventionally, a tilt sensor including a swingable electrode and a fixed electrode is known. When the tilt sensor tilts, the swingable electrode swings according to the tilt, and the distance from the fixed electrode changes. Since the amount of charge accumulated between the electrodes changes due to the change in the interval, an inclination sensor that detects the inclination by detecting the change in the amount of charge is known.
JP 2003-329444 A

  However, when the tilt sensor is miniaturized in accordance with the demand for miniaturization of the device, the amount of charge that can be accumulated between the electrodes decreases. As a result, the amount of change in charge caused by the oscillation of the electrode is also reduced, so that the S / N ratio of the signal output from the tilt sensor is lowered according to the amount of change in charge.

  An object of this invention is to obtain the inclination sensor which can detect the inclination of the attached member correctly.

  The tilt sensor according to the first invention of the present application has a light splitter that transmits incident light or changes a traveling direction thereof, a mirror that reflects incident light, and an elastic member that supports the mirror, and depends on the direction of gravity. The tilting mirror that changes the reflection direction of the incident light after the elastic member is deformed and the position detection unit that detects the position irradiated with the incident light, and the light whose traveling direction has been changed by the light splitter It is guided to the tilting mirror and reflected toward the position detection unit by the tilting mirror.

  An image sensor is suitable for the position detection unit.

  The position detection unit preferably detects the inclination by comparing the light incident position when the elastic member is not deformed with the light incident position when the elastic member is deformed.

  A first lens that converts incident light into parallel light; and a light-emitting element that projects light onto the light splitter; the first lens is provided between the light splitter and the tilt mirror; It is preferable to convert light traveling from the light splitter toward the tilt mirror into parallel light.

  Second and third lenses that convert incident light into parallel light and a light emitting element that projects light onto the second lens are further provided, and the second lens is disposed between the light emitting element and the light splitter. The third lens is provided between the light splitter and the position detector, and detects the light emitted from the light splitter. It is preferable to collect light toward the part.

  As described above, according to the present invention, an inclination sensor capable of accurately detecting the inclination of an attached member is obtained.

  A first embodiment according to the present invention will be described below with reference to FIGS.

  The tilt sensor 100 includes a laser diode 110 that is a light emitting element that emits laser light, a first collimator lens 130 that is a first lens that converts diffused light into parallel light, and a tilt mirror whose reflection angle changes due to its own weight. 140, an image sensor 150 that forms an interference fringe measurement unit, for example, a CCD, and an optical splitter that splits incident light, that is, a beam splitter 120.

  The inclined mirror 140 includes a rectangular tube-shaped frame body 144, a weight body 142 that is a rectangular parallelepiped having a constant weight, and an elastic member 143 that is provided inside the frame body 144 and connects the frame body 144 and the weight body 142. It consists of. The weight body 142 has a constant weight, one side forms a mirror surface 141, and is provided inside the frame body 144. The elastic member 143 connects the side surface perpendicular to the mirror surface 141 in the weight body 142 and the inner side surface of the frame body 144. The tilting mirror 140 is integrally formed of silicon.

  The beam splitter 120 is a rectangular parallelepiped and has a reflecting surface 121 that is a plane passing through the two sides. Part of the light incident on the reflecting surface is transmitted through the reflecting surface 121, and the rest is reflected.

  The laser diode 110 is attached to a specific surface of the beam splitter. On the surface of the beam splitter 120, the first collimator lens 130 is attached to a surface that is orthogonal to the surface to which the laser diode is attached and does not intersect with the reflection surface 121. The imaging element 150 is attached to the back surface of the surface to which the first collimator lens 130 is attached so that the imaging surface 151 faces the surface.

  A frame body 144 of the tilt mirror 140 is attached to the back surface of the surface of the first collimator lens 130 attached to the beam splitter 120. That is, the weight 142 and the mirror surface 141 can swing with respect to the beam splitter 120.

  The laser diode 110, the first collimator lens 130, and the image sensor 150 are fixed to the beam splitter 120.

  The imaging element 150 transmits an image formed on the imaging surface 151 to the tilt angle calculation unit 160. The tilt angle calculation unit 160 calculates the tilt angle of the tilt sensor 100 using the image transmitted from the image sensor 150.

  By directly providing the laser diode 110, the first collimator lens 130, the tilting mirror 140, and the image sensor 150 on the beam splitter 120, the tilt sensor 100 can be reduced in size.

  Further, by using a surface emitting laser diode as the laser diode 110, the inclination sensor 100 can be further reduced in size.

  Next, the function and operation of the tilt sensor 100 will be described with reference to FIGS.

  The light emitted from the laser diode 110 enters the beam splitter 120. A part of the incident light is reflected by the reflecting surface 121 and is irradiated to the first collimator lens 130. The first collimator lens 130 converts incident light into parallel light.

  The parallel light enters the inclined mirror 140 and is reflected by the mirror surface 141. The light reflected by the mirror surface 141 passes through the first collimator lens 130 again. Part of the light that has passed through the first collimator lens 130 passes through the reflecting surface 121 and is condensed toward the imaging surface.

  Since the weight body 142 having the mirror surface 141 is connected to the frame body 144 via the elastic member 143, the weight body 142 can swing with respect to the beam splitter 120. When the tilt sensor 100 is not tilted with respect to gravity, the mirror surface 141 is parallel to the surface to which the tilt mirror 140 is attached in the beam splitter 120 (see FIG. 1). The reflected light at this time is called reference light, and is indicated by a broken line in FIG. The inclination angle calculation unit 160 stores in advance the position where the reference light is irradiated on the imaging surface.

  On the other hand, when the tilt sensor 100 is tilted with respect to gravity, the mirror surface 141 is not parallel to the surface of the beam splitter 120 to which the tilt mirror 140 is attached. Therefore, the optical paths of the light incident on the mirror surface 141 and the reflected light are not the same (see FIG. 2). The reflected light at this time is called measurement light, and is indicated by a one-dot chain line in FIG.

  Thereby, in the imaging surface 151, a shift | offset | difference arises between the position where reference light is irradiated, and the position where measurement light is irradiated. By measuring this deviation, the tilt angle θ of the tilt sensor 100 is measured.

The image sensor 150 captures an image of the irradiated light and transmits it to the tilt angle calculator 160. The inclination angle calculation unit 160 compares the irradiation position of the reference light stored in advance with the irradiation position of the measurement light in the received image, and measures the deviation amount at the irradiation position, whereby the inclination angle of the inclination sensor 100 is measured. The inclination direction of the inclination sensor 100 is measured by measuring θ and measuring the deviation direction.
The equation for calculating the inclination angle θ from the deviation y is as follows.
θ = y / (2 × f)
Here, f is the focal length of the first collimator lens 130.

  In this embodiment, since the measurement light needs to be applied to the imaging surface 151, the distance between the laser diode 110 and the beam splitter 120 is determined by the first collimator lens 130 using the diffused light from the laser diode 110. The distance is limited such that the light can be condensed on the imaging surface 151.

  According to this embodiment, a signal with a high S / N ratio can be obtained with a small number of parts.

  Next, a second embodiment will be described with reference to FIGS. The description of the same configuration as that of the first embodiment is omitted.

  The tilt sensor 200 includes a laser diode 210 that is a light emitting element that emits laser light, second and third collimator lenses 230 and 270 that are second and third lenses that convert diffused light into parallel light, and its own weight. It is mainly composed of an inclined mirror 240 whose reflection angle changes, an image sensor 250 that forms an interference fringe measurement unit, for example, a CCD, and a light splitter that splits incident light, that is, a beam splitter 220.

  The tilt mirror 240 includes a frame body 244, a weight body 242, and an elastic member 243. A mirror surface 241 is formed on one surface of the weight body 242. Since the configuration of the beam splitter 220 is the same as that of the first embodiment, description thereof is omitted.

  The second and third collimator lenses 230 and 270 are attached to two surfaces that are orthogonal to each other among the surfaces that do not intersect the reflecting surface 221 on the surface of the beam splitter 220, that is, the surfaces that face the reflecting surface 221. In the beam splitter 220, the inclined mirror 240 is attached to a surface that is orthogonal to the surface to which the second collimator lens 230 is attached and that faces the surface to which the third collimator lens 270 is attached.

  The tilt mirror 240 is attached to the beam splitter 220 by fixing the frame body 244 to the surface of the beam splitter 220. That is, the weight body 242 and the mirror surface 241 are swingable with respect to the beam splitter 220.

  A laser diode 210 is attached to the back surface of the second collimator lens 230 attached to the beam splitter 220.

  In the third collimator lens 270, an imaging element 250 is attached to the back surface of the surface attached to the beam splitter 220 so that the imaging surface 251 faces the surface.

  That is, the laser diode 210, the second and third collimator lenses 230 and 270, and the image sensor 250 are fixed to the beam splitter 220.

  The image sensor 250 transmits the image formed on the imaging surface 251 to the tilt angle calculator 260.

  Next, the function and operation of the tilt sensor 200 will be described with reference to FIGS.

  The diffused light emitted by the laser diode 210 enters the second collimator lens 230 and is converted into parallel light. The parallel light enters the beam splitter 220. A part of the incident light is reflected by the reflecting surface 221 and enters the inclined mirror 240. The incident light is reflected by the mirror surface 241 and enters the beam splitter 220. Part of the light incident on the beam splitter 220 passes through the reflecting surface 221 and enters the third collimator lens 270. The third collimator lens 270 collects incident light toward the imaging surface 251.

  Since the weight body 242 having the mirror surface 241 is connected to the frame body 244 via the elastic member 243, the weight body 242 can swing with respect to the beam splitter 220. When the tilt sensor 200 is not tilted with respect to gravity, the mirror surface 241 is parallel to the surface on which the tilt mirror 240 is attached in the beam splitter 220 (see FIG. 3). The reflected light at this time is referred to as reference light, and is indicated by a broken line in FIG. The inclination angle calculation unit 260 stores in advance the position where the reference light is irradiated on the imaging surface.

  On the other hand, when the tilt sensor 200 is tilted with respect to gravity, the mirror surface 241 is not parallel to the surface on which the tilt mirror 240 is attached in the beam splitter 220. For this reason, the optical paths of the light incident on the mirror surface 241 and the reflected light are not the same (see FIG. 4). The reflected light at this time is called measurement light, and is indicated by a one-dot chain line in FIG.

  Thereby, in the imaging surface 251, a shift | offset | difference arises between the position where reference light is irradiated, and the position where measurement light is irradiated. By measuring this deviation, the tilt angle θ of the tilt sensor 200 is measured. The inclination angle θ is calculated in the same manner as in the first embodiment.

  According to the present embodiment, since the second collimator lens 230 is provided between the laser diode 210 and the beam splitter 220, the diffused light from the laser diode 210 is not diffused more than necessary, and the position of the laser diode 210 is limited. Not.

  In addition, according to these embodiments, since the signals output from the tilt sensors 100 and 200 are signals output from the image sensors 150 and 250, compared with the conventional tilt sensor that outputs the charge accumulated between the electrodes. Thus, a signal having a high S / N ratio can be obtained.

  In addition, since these embodiments use light interference, it is possible to measure a minute inclination angle by adjusting the elasticity of the elastic members 143 and 243.

  The inclined mirrors 140 and 240 do not have to be made of silicon, and may not be formed integrally.

It is the figure which showed notionally the cross section of the inclination sensor by 1st Embodiment. It is the figure which showed notionally the cross section when an inclination sensor inclines. It is the figure which showed notionally the cross section of the inclination sensor by 2nd Embodiment. It is the figure which showed notionally the cross section when an inclination sensor inclines.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Inclination sensor 110 Laser diode 120 Beam splitter 130 1st collimator lens 140 Inclination mirror 150 Imaging element 160 Inclination angle calculation part

Claims (5)

A light splitter that transmits incident light or changes a traveling direction thereof; and
An inclined mirror that includes a mirror that reflects incident light and an elastic member that supports the mirror, the elastic member deforms according to the direction of gravity, and changes a reflection direction of incident light;
A position detection unit that detects a position irradiated with incident light,
A tilt sensor in which the light whose traveling direction is changed by the light splitter is guided to the tilt mirror and reflected toward the position detection unit by the tilt mirror.   The tilt sensor according to claim 1, wherein the position detection unit is an image sensor.   The position detection unit detects an inclination by comparing a light incident position when the elastic member is not deformed with a light incident position when the elastic member is deformed. The tilt sensor described in 1. A first lens that converts incident light into parallel light;
A light emitting element that projects light onto the light splitter;
2. The tilt sensor according to claim 1, wherein the first lens is provided between the light splitter and the tilt mirror, and converts light traveling from the light splitter toward the tilt mirror into parallel light. Second and third lenses for converting incident light into parallel light;
A light emitting element that projects light onto the second lens;
The second lens is provided between the light emitting element and the light splitter, and converts light from the light emitting element toward the light splitter into parallel light,
2. The tilt sensor according to claim 1, wherein the third lens is provided between the light splitter and the position detection unit, and collects light emitted from the light splitter toward the position detection unit. .

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