JPS6340805A - Inclination detector - Google Patents

Abstract

PURPOSE:To enable measurement of an inclination with a desired surface as reference, by a method wherein the light from a light emitting element is projected on a mirror surface fixed on an object to be detected and the reflected light thereof is focused on a position detecting element by a light receiving optical system to detect a signal. CONSTITUTION:Light emitted from a light emitting element 1 is turned to a parallel light by a collimation optical system 3 to be incident into a mirror surface 41 inclined by an angle theta1. The reflected light thereof forms a spot at a point P1 on a light receiving surface of a detecting element 2a by a focusing optical system 3. The reflected light of the light incident into a mirror surface 42 inclined by an angle theta2 forms a spot at the point P2 on a light receiving surface of a detecting element 2b. Distances l1 and l2 are detected from the center of the light emitting element 1 to the points P1 and P2 thereby enabling measurement of the inclination of an object to be detected with the mirror surfaces 41 and 42 fixed thereon.

Description

[Detailed description of the invention] Background of the invention The present invention relates to a tilt detection device.

A conventional tilt detection device is a tilt sensor that detects the tilt with respect to the direction of electric power. These tilt sensors include capacitance type, shield plate type (photoelectric type), magnetic fluid type, and bubble level (photo detection type).

Among these, the magnetic fluid type can also be used as an acceleration sensor.

In any of the above-mentioned methods, the conventional tilt sensor utilizes 1 gravity, so there is a problem in that it can only measure the deviation (inclination) of the tilted surface (the upward facing surface) from the horizontal plane. Also, since it uses two gravity forces, it is always affected by inertial force, so there is a limit to how fast the response speed can be increased.

SUMMARY OF THE INVENTION The present invention provides an apparatus that can measure tilt based on any plane by using only optical techniques.

The tilt detection device according to the present invention includes two light emitting elements, a projection optical system for converting the output of one light emitting element into parallel light, and a mirror im for reflecting the projected light in conjunction with a tilted object. , a light receiving optical system that collects reflected light from the Wt surface, and a position detection element that receives the focused light and outputs a signal according to its position.

In the above configuration, the direction of reflection of the projected light changes depending on the inclination of the mirror surface, and the convergence position of one reflected light on the position detection element changes. Since the convergence position of the reflected light has a certain relationship with the inclination angle of the mirror [al, by detecting this convergence position, the inclination of the mirror surface, that is, the inclination of the object to be detected in conjunction with the mirror surface can be detected.

According to this invention, since the inclination of the object to be detected is detected optically and electrically, it is possible to detect the inclination without being influenced by gravity or inertial force. Therefore, it is possible to detect not only the inclination with respect to the seven horizontal planes, but also the inclination with respect to any reference plane, and the response speed is improved. Furthermore, since the optical system is used for I'll, the apparatus can be made compact and lightweight. By using a position detection element, it is possible to detect not only the position in the primary direction but also the position in the two-dimensional direction, so it is also possible to measure the inclination of the object to be detected in two directions.

DESCRIPTION OF THE EMBODIMENTS FIGS. 1 and 2 show an apparatus for detecting tilt in one direction. The light emitting element 1 is composed of a semiconductor laser, a gas laser, a light emitting diode, or the like. At the upper and lower positions of this light emitting element 1 in FIG.
2b is placed. As a position detection element, a PSD (Position ψ sensitive device: Po5ition 5 sensitive device) as described later is used.
vice) or a photodiode (PD) array.

These light-emitting cords 1 and position-detecting cords 2a.

An optical system 3 is placed in front of the lens 2b. The optical system 3 includes a collimating optical system for collimating the light emitted from the light emitting element 1 and projecting it onto a mirror surface 41 (or 42, etc.), and a position detecting element 2a or 2a for condensing the reflected light from the mirror surface. and a focusing optical system for forming a spot on 2b. For one-dimensional (one direction) tilt detection, a cylindrical lens is used as a collimating optical system.

In the case of two-dimensional (two-direction) tilt detection, a Fresnel lens, a school glass lens, or the like may be used. If the light emitted from the light emitting element 1 is collimated, this optical system is not necessarily 8-dimensional. As shown in FIG. 1, one optical system can serve as both the collimating optical system and the focusing optical system, or they can be provided separately.

The mirror surface is fixed to the object whose inclination is to be detected, or is provided via a suitable mechanism, and is configured to move in conjunction with the inclination of the object. Position of mirror without tilt (
The reference plane) is indicated by a chain line M, the position where the upper part is tilted forward (in the direction of the optical system 3) is indicated by reference numeral 42, and the position where the upper part is inclined backward is indicated by reference numeral 41. It is preferable that the center of inclination (rotation center) O of this mirror surface is on the optical axis of the projected light from the light emitting element 1.

The light emitted from the light emitting element 1 is converted into parallel light by the collimating optical system 3 and projected onto the rotation center O of the mirror surface. As shown by the reference numeral 41, the upper part of the mirror surface faces backward at an angle θ1.
If the reflected light is tilted by 2θ1, the reflected light is shifted (tilted) by 2θ1 relative to the incident light.

The light is focused by the focusing optical system 3 and forms a spot at a point P1 on the light receiving surface of the upper position detection element 2a. As shown by reference numeral 42, when the L portion of the mirror surface is tilted forward by θ2, 2
The reflected light is focused on a point P2 of the lower position detection element 2b-1=. The distance 1° C.2 from the center of the light emitting element 1 to each point P 2 is a function of the inclination angles θ 2 , θ 2 of the mirror surface.

Further, the direction of inclination of the mirror surface is determined depending on which of the position detection elements 2a and 2b the reflected light is detected. Therefore, by detecting the distance , 12, the inclination angle θ
, θ, etc. can be measured.

When the inclination of the mirror surface is limited to the front or the rear, only one of the one position detection elements 2a and 2b may be provided.

FIG. 3 shows the position detection principle and detection circuit when a PSD is used as the position detection element.

As PSD itself is well known, Lateral Photo Erf'cct on a semiconductor surface
There are two types: one for one-dimensional 21' measurement, which has electrodes along two opposing sides of the light-receiving surface, and one for two-dimensional meter t11'l, which has electrodes on four sides. . In any case, the photocurrents obtained from each electrode are mutually calculated (added).

One-dimensional measurement (for example, PSD
(obtaining the position in the Y direction of the light focused on the PSD) or two-dimensional measurement (obtaining the position in the X and Y directions of the light focused on the PSD).

In FIG. 3, photocurrent Y1. obtained from a pair of electrodes 11 provided on PSD 2a for one-dimensional measurement. Y2 is amplified by the amplifier 12, and then sent to the subtraction circuit 13. An adder circuit 14 calculates their difference and sum, respectively. Further, in the division circuit 15, the subtraction result is divided by the addition result to obtain a signal representing the position of the spot P1 in the Y-axis direction.

FIG. 4 shows an example of another position detection element.

This position detection element 21 is a PD array, and has a large number of P
D21a are arranged concentrically and radially. The position of the spot can be determined by which PD 21a detects the focused spot of the reflected light. The PDs may be arranged like the eyes of the base, or may be arranged in any other arbitrary arrangement.

Figure 5 shows a PSD for two-dimensional measurement around one light emitting element 1.
(Electrodes are not shown) A position detection device is shown in which four electrodes 22a to 22d are arranged. When the position detection elements shown in FIGS. 4 and 5 are used, two-dimensional (two-direction) inclination detection becomes possible.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show an embodiment of this invention.
FIG. 1 is an overall configuration diagram, and FIG. 2 is a front view of a light emitting element and a position detecting element. FIG. 3 is a block diagram showing the configuration of a PSD for one-dimensional measurement and a position detection circuit, and FIGS. 4 and 5 are front views showing examples of the configuration of a two-dimensional position detection element. 1... Light emitting element. 2a, 2b, 22a to 22d-PSD (position sensitive and devices). 3...Optical system, 41.42. M...Mirror surface. 21...PD array position detection element. 21a-PDo Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kenji Ushiku (1 other person) Figure 1 Figure 3

Claims (1)

[Scope of Claims] A light emitting element, a projection optical system for projecting the output of the light emitting element, a mirror surface for reflecting the projected light in conjunction with an inclined object to be detected, and a light receiving device for condensing the reflected light from the mirror surface. A tilt detection device comprising: an optical system; and a position detection element that receives focused light and outputs a signal according to its position.