JP2572637B2 - Configuration of Optical Distance Sensor for Surface Condition Detection - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical distance detecting device for detecting a distance to a surface of an object, and more particularly to an inclination, unevenness, edge, and the like of the surface of the object. The present invention relates to a configuration of an optical distance detection sensor suitable for detecting or tracking a ridge line or the like.

(Prior Art) For optical distance detection, a bright spot image position generated by projecting a light beam on the surface of an object is detected by an image position detecting means, and a bright spot image is detected based on the principle of triangulation. A method for determining a three-dimensional position of a point is widely used. A point measurement type distance sensor that detects the distance in the light beam projection direction, a light cutting method that obtains distance information along the bright line by projecting slit light, that is, a light-section method that obtains a cross-sectional shape, and a lattice point or ring shape A method of projecting such light and extracting information on the inclination, projection, edge, and the like of the surface of the target object from the state of the observed lattice point or annular pattern distortion or the like has been attempted.

(Problems to be Solved by the Invention) In order to detect a surface state of an object such as an inclination or an edge using a point measurement type distance detection sensor which has been widely used conventionally, mechanical movement of the distance sensor is required. However, it is difficult to speed up the extraction and tracking of the features of the surface of the object. In the light cutting method, although a cross-sectional shape can be obtained by one slit scan, the feature extraction characteristic has directionality, and tracking requires rotation of a sensor or the like. Image processing is required for observing distortion of the projected pattern of annular light or lattice point light, which is disadvantageous in increasing the speed. In addition, a new sensor that projects an annular light and obtains distance information in all directions at once has been proposed. However, this sensor also has a shortage of light amount and it is difficult to improve the resolution in the angle direction.

(Means for Solving the Problems) In order to solve the above-mentioned problems, it is possible to extract the inclination of the surface of the object, the state of the edge, and the like at a high speed, and to obtain a detection characteristic in an isotropic direction. A light beam scanning and projecting means for projecting onto a target object surface along a scanning cylindrical surface generating line and generating a luminescent spot on the target object surface, and two axial directions perpendicular to the center axis of the scanning cylindrical surface and orthogonal to each other An optical distance detection sensor is provided by providing a target point direction detecting means for detecting the direction of the bright point with respect to.

(Operation) The light beam is scanned by the light beam scanning and projecting means so that its passing locus forms a cylindrical surface (scanning cylindrical surface).
Bright spots are sequentially projected and generated on an annular object surface provided as an intersection between the object surface and the scanning cylindrical surface. Two orthogonal to each other in a plane perpendicular to the central axis of the scanning cylindrical surface;
The azimuth of the luminescent spot with respect to the axial direction is detected by the reference point azimuth detecting means.

(Effect of the Invention) According to the present invention, distance information along an annular trajectory around a point of interest on the surface of an object can be acquired at high speed. Has no directivity in detection characteristics. Since the beam light is used as the probe light, the problem of insufficient light quantity does not occur. Since the light beam is sequentially scanned along the scanning cylindrical surface, advantages such as improvement in resolution in the angular direction can be obtained. Therefore, features such as the inclination and edge of the object surface and the direction thereof can be extracted with isotropic detection characteristics without being affected by the direction, and a distance sensor suitable for tracking the surface of the object can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1A and 1B are a plan view and a side view, respectively, of an embodiment of the configuration of an optical distance sensor for detecting a surface state according to the present invention. Light beam B from the configured source S from a laser diode or the like, the light beam scanning unit S _B, is projected in the direction of the generatrix of the scanning cylindrical surface of radius r, is rotated scanned along the scan cylindrical surface. Light beam scanning means S _B
Specific configuration of is detailed below with reference to FIGS. 4 and 5, for example, a mirror M _A M _R is disposed at a position of the central axis A _X and on the radius r of the distance sensor, These are the central axes
All you have to do is rotate around A _X. The light spots T, T ', T "on the surface of the object O are generated by the light beams B, B', B" projected along the scanning cylindrical surface generating line. The distance sensor central axis A _X plurality of one-dimensional gauge azimuth detector D disposed around the, x-direction x _m and y-direction orientation y _m of bright point T is detected.

3-dimensional coordinate value of the bright point T and (x, y, z), the following relationship between the x-direction orientation x _m and y-direction orientation y _m which is detected by the 1-dimensional gauge azimuth detector D is satisfied.

The position of the bright point in the z direction can be calculated by the following equation by modifying equation (1) and eliminating θ.

z = ar / (x _m ² + y _m ² ) ^1/2 (3) The x value and the y coordinate value of the luminescent spot are determined by substituting the value of z in the expression (3) into the expression (2). be able to.

These operations can be executed by converting the values x _m and y _m of the output signal from the one-dimensional target direction detector D from analog to digital and inputting them to a computer. When x _m and y _m are obtained as analog signals, these operations can also be performed by using an analog operation circuit. An example of a block diagram of an arithmetic circuit for that purpose is shown in FIG. High-speed and continuous execution can be achieved by using an analog arithmetic circuit.

Outputs x _m and y _m from the one-dimensional target direction detector D are multipliers X
Is multiplied by After the multiplication results x _m ² and y _m ² are added by the adder 、, the square root calculator Gives the square root. The value of the square root thus obtained is input to the divider ÷ and used as a divisor for dividing the radius r of the scanning cylindrical surface. The output from the divider ÷ is input to a coefficient unit a, where the distance z is obtained, and is multiplied by the outputs x _m and y _m from the one-dimensional target direction detector D to calculate x and y.

As the one-dimensional target direction detector D, one having a structure in which a cylindrical lens and a one-dimensional image position detecting element (line sensor) are combined can be used. In particular, by using a one-dimensional target direction detector (Japanese Patent Application No. 61-194743) having a structure in which a parallel plane mirror is arranged between an imaging lens and a one-dimensional image position detecting element, an optical system based on the present invention is provided. The distance sensor can be significantly reduced in size. In FIGS. 1A and 1B, the one-dimensional target direction detector D is arranged outside the cylindrical surface (scanning cylindrical surface) drawn by the projection light beam B, but is arranged inside the scanning cylindrical surface. You may. Further, instead of a plurality of one-dimensional target direction detectors, a configuration may be adopted in which a two-dimensional target direction detector is arranged such that the detection center of the two-dimensional target direction detector is located within the scanning cylindrical plane.

FIG. 2A and FIG. 2B are a plan view and a side view, respectively, showing the configuration of an optical distance sensor for detecting a surface state when the two-dimensional target direction detector is used. 2-dimensional gauge azimuth detector D ₂ is constituted by two-dimensional semiconductor image position detector (area sensor) and the imaging optical system (lens). 1A and FIG.
The configuration is the same as that shown in FIG.
X-direction orientation x _m and y directions azimuth of the bright point T formed on
y _m is detected by a single two-dimensional target direction detector D ₂ .

In FIGS. 4 and 5 illustrates a specific configuration example of a light beam scanning means S _B used in the present invention.

Light beam scanning means S _B shown in Fig. 4, and the distance sensor central axis A _X, the mirror in the position of the light beam projected cylindrical surface M _A and M
The _R, arranged so that they are parallel to each other, has a structure to rotate on the center axis of the distance sensors rotation axis A _X. Incidentally, a suitable concave mirror instead of parallel mirrors M _R to the position of the light beam projection plane arranged by so as to converge the incident beam, the upper surface of the object is possible to form a sharp bright spot Become.

Light beam scanning means S _B shown in Fig. 5, a conical surface mirror M _C over the entire circumference at the position of the light beam projected cylindrical surface fixedly arranged,
Only mirror M _B on the central axis has a structure for rotating a can reduce the inertia of the moving parts, it can be realized a possible scanning speed response.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view and a side view, respectively, showing the configuration of an optical distance detector sensor for a surface state detector based on the present invention when a one-dimensional gauge azimuth detector is used. FIG. 2B is a plan view and a side view showing the configuration of an optical distance detector sensor for a surface state detector based on the present invention when a two-dimensional target direction detector is used, and FIG. FIG. 4 is a block diagram of an analog arithmetic circuit for calculating the position of a luminescent spot from the obtained azimuth signal of the luminescent spot. FIGS. 4 and 5 are perspective views showing a specific configuration example of a light beam scanning means used in the present invention. (Reference Numerals) S ...... source, B, B ', B " ...... light beam, S _B ...... light beam scanning unit, T, T', T" ...... bright spots, D ...... 1 dimensional gauge azimuth detector, I ...... luminescent spot image, x _m ...... x direction detecting orientation, y _m ...... y direction detecting azimuth, r ...... scan cylindrical surface radius, a ...... 1 dimensional gauge azimuth detector nodes and image Distance from the surface, O: object, A _X: central axis of cylindrical surface, x, y, z: three-dimensional coordinate value, D _2: two-dimensional target point direction detector, ×: multiplier , Σ …… Adder, ÷ …… Divider, a… Coefficient unit, M _A , M _R … Mirror, M _C … Conical mirror.

Claims (3)

(57) [Claims] 1. A light beam scanning and projecting means for projecting a light beam on a target object surface along a generatrix direction of a scanning cylindrical surface to generate a bright spot on the target object surface, and A configuration of an optical distance sensor for detecting a surface state of an object, comprising: a reference point direction detecting means for detecting a direction of the bright spot with respect to two axial directions orthogonal to each other in a vertical plane. 2. A method according to claim 1, wherein said reference point azimuth detecting means is arranged around a central axis of said scanning cylindrical surface, and each azimuth detecting direction is:
2. A configuration of an optical distance sensor for detecting a surface state according to claim 1, further comprising a plurality of one-dimensional reference point azimuth detecting means arranged in a direction perpendicular to the center axis of the scanning cylindrical surface and orthogonal to each other. . 3. The two-dimensional target point direction detecting means having a detection center on the central axis of the scanning cylindrical surface and detecting the direction of a bright point with respect to an axial direction orthogonal to each other. The structure of the optical distance sensor for detecting a surface state according to claim 1, wherein: