JPH11211460A - Range measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a range measuring device capable of performing a highly precise range finding even if a secondary multiple reflected light is present. SOLUTION: This device is provided with a light source 1; a one-dimensional photodetector 9 for converting a received light energy into an electric signal according to the position and intensity of the light; an imaging means for imaging the reflected light of the optical beam from the light source reflected by the surface of a matter to be measured on the light receiving surface of the photodetector 9 as a light spot; a first projection control means for controlling the optical beam emitted from the light source to a first axial direction by a first rotating mirror 13; a second projection control means for controlling the light leaving the first projection control means to a second axial direction by a second rotating mirror 12; and a light receiving control means for controlling the imaging of the light spot formed in a position where the optical beam from the light source 1 is emitted to the matter to be measured onto the photodetector by a third rotating mirror 14 synchronized with the second rotating mirror 12 of the second projection control means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device (range sensor), and more particularly to a technology which is effective when applied to a distance measuring technology in various manufacturing and processing devices, measurement and inspection devices, and the like.

[0002]

2. Description of the Related Art A non-contact type distance sensor is known as a distance measuring device (distance sensor) incorporated in various types of manufacturing and processing devices, measurement and inspection devices, and the like. Examples of the non-contact type distance sensor include an ultrasonic sensor and a range sensor (laser range sensor) using a laser, and a laser range sensor is used for applications requiring high speed and high accuracy. FIG. 3 is a diagram for explaining the basic principle of a conventional laser range sensor. In the figure, 1 is a light source, 2
Is a light beam emitted from the light source 1, 3 is an object to be measured, 7 is
Is a light reflected on the surface of the measuring object 3, 8 is an optical component, 9 is a light receiving element, and 10 is a light receiving surface of the light receiving element 9.
As shown in FIG. 1, in the conventional laser range sensor, a light spot is generated on the surface of the measuring object 3 by the light beam 2 emitted from the light source 1, and light (reflected light 7) from this light spot
Is imaged as a light spot on a light receiving surface 10 of a light receiving element 9 by an optical component (light receiving lens) 8. At this time, as shown in FIG. 4, the imaging position on the light receiving surface 10 changes depending on whether the measurement target 3 is near or far. In FIG. 4, if the correspondence between the distance to the measurement object (3a, 3b) and the image formation position is checked in advance using a measurement object with a known distance, the image formation position is compared with the unknown distance. You can know the distance from.

Here, the light receiving element 9 is provided on the light receiving surface 1.
An element that can convert the position of a light spot imaged to 0 into an electric signal, for example, a one-dimensional CCD (charge coupled device)
And one-dimensional PSD (posision sensitive device). A mirror, a prism, a lens, and the like are generally used as the optical component 8 for guiding the reflected light 7, but FIG. 3 shows a laser range sensor using only a lens as the optical component. The laser range sensor is described in, for example, "How to Use Optical Components and Points to Consider" (published by Tetsuo Sueda, Optronics).

FIG. 5 is a diagram showing a schematic configuration of a conventional laser range sensor. The laser range sensor shown in FIG. 5 has two scanner mirrors (1) on the scanning side (light projection side).
2, 13), and a two-dimensional light receiving element 11 is provided on the light receiving side instead of the one-dimensional light receiving element 9. In the laser range sensor shown in FIG. 5, by controlling the scanner mirror 13 and the scanner mirror 12 to scan the light beam 3 from the light source in the X-axis direction and the Y-axis direction, the distance of the two-dimensional area is controlled. Can be measured.

[0005]

The point that determines the distance measurement accuracy of the laser range sensor is whether or not the imaging position of the light spot on the light receiving surface 10 of the light receiving element 9 can be accurately known. When the light receiving element 9 is formed of a one-dimensional CCD, the light receiving surface 10 is composed of a plurality of pixels arranged on a straight line, and the amount of light received by each pixel can be obtained as an electric signal. Therefore, if the peak position of the light amount or the weighted average position of the light amount is obtained by the electric signal processing, it is possible to know which pixel position corresponds to the imaging position of the light spot. Light receiving element 9 is one-dimensional PS
In the case of D, the PSD output is subjected to the electric signal processing to obtain the weighted average position of the light amount as a ratio to the PSD length, so that the imaging position of the light spot can be known.
This is shown in FIG.

As described above, in principle, the laser range sensor receives the light (regular reflected light 7) reflected only once on the surface of the measurement target 3 by the light receiving element 9 and determines the distance to the measurement target 3. Measuring. If the surface of the measuring object 3 is glossy, the light beam reflected on the surface of the measuring object 3 may be reflected on another surface (multiple reflection) and then return to the sensor. In some cases, it may not be possible to correctly know the imaging position of the regular reflected light 7. In this case, the distance measurement accuracy is significantly deteriorated.

In order to explain the cause of this deterioration in more detail, the reason why multiple reflections affect measurement accuracy will be described. When there is multiple reflection, since there are a plurality of light spots on the light receiving surface 10, the peak of the regular reflected light 7 is not always the highest in the method using the peak position of the light amount. Cannot be obtained correctly. Further, in the method using the weighted average position of the light quantity, the weighted average shifts to the side where the multiple reflected light exists, so that the imaging position of the regular reflected light 7 cannot be correctly obtained. This is shown in FIG. Depending on the number of times of reflection before the light exits the light source 1 and returns to the light receiving element 9, this multiple reflection is like a secondary (two times) multiple reflection, a third order (three times) multiple reflection, a fourth order (four times) multiple reflection. are categorized. FIG. 8 shows an example of multiple reflection.
A state where the secondary multiple reflected light 15 is generated is shown. As shown in FIG. 9, the secondary multiple reflected light 15 is likely to occur when the measurement target 3 is L-shaped. In particular, in the conventional range sensor shown in FIG. 5, the influence of the secondary multiple reflected light cannot be avoided. There is a problem that the distance to the object 3 cannot be measured accurately.
Further, in the conventional range sensor shown in FIG.
The two-dimensional light receiving element 11 is required.
No. 1 had a problem that the structure was complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a distance measuring device that can accurately measure a distance even when there is a secondary multiple reflected light. It is to provide a technology that enables measurement. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0009]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. That is, the present invention relates to a distance measuring device, wherein a light source, a one-dimensional light receiving element for converting received light energy into an electric signal corresponding to the position and intensity of light, and a light beam emitted from the light source are measured. An image forming means for forming an image of the reflected light reflected on the surface of the object as a light spot on the light receiving surface of the light receiving element; and a first rotating mirror, which is emitted from the light source by the first rotating mirror. A first rotation control means for controlling the light beam in a first axis direction; and a second rotating mirror, the first light control means controlling the light beam in the first axis direction by the second rotation mirror. A second light emitting control means for controlling the light beam in the second axial direction; and a third rotating mirror synchronized with a second rotating mirror of the second light emitting control means, wherein the third rotating mirror is provided. The light beam emitted from the light source irradiates the object to be measured. Characterized in that it comprises a light receiving control means for controlling the imaging onto the one-dimensional light receiving element on the light spot formed at the positions.

Further, the present invention is characterized in that a two-dimensional light receiving element is used instead of the one-dimensional light receiving element.

Further, in the present invention, the second rotating mirror and the third rotating mirror are integrally formed, and the second rotating mirror and the third rotating mirror are integrated with each other.
The light emission control means (or the light reception control means) is characterized in that the light emission control means (or the second light emission control means) is also used.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, components having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted.

[First Embodiment] FIG. 1 is a diagram showing a schematic configuration of a distance measuring apparatus according to a first embodiment of the present invention. 1, reference numeral 1 denotes a light source, 2 denotes a light beam emitted from the light source 1, 3 denotes an object to be measured, 7 denotes reflected light reflected on the surface of the object 3 to be measured, 8 denotes an optical component, 9 denotes a light receiving element, and 12 denotes a light receiving element. , 13,
Reference numeral 14 denotes a scanner mirror. In the distance measuring device of the present embodiment, two scanner mirrors (first rotating mirror 13 and second rotating mirror 12) are added to the light projecting side, and one scanner mirror ( A third rotating mirror 14) is added, and a one-dimensional light receiving element 9 is used as a light receiving element. In the distance measuring device of the present embodiment, on the light projecting side, the light beam 3 from the light source is scanned in the X-axis direction by the scanner mirror 13 of the first light projecting control means, and The scanner mirror 12 scans the light beam 3 from the light source scanned in the X-axis direction by the scanner mirror 13 in the Y-axis direction to generate a light spot on the surface of the measurement target 3. On the light receiving side, light from a light spot generated on the surface of the measurement target 3 (reflected light 7 reflected by the measurement target 3) is scanned in the Y-axis direction by the scanner mirror 14 of the light reception control unit. . The reflected light 7 reflected by the measurement target 3 scanned by the scanner mirror 14 is coupled onto a one-dimensional light receiving element 9 via an optical component 8 such as a lens. Here, the scanner mirror 12 and the scanner mirror 14 are controlled in synchronization.

When the scanner mirror 14 is not provided as in the conventional range sensor shown in FIG.
The reflected light 7 reflected by the optical element 8 forms an image at a corresponding point of the two-dimensional light receiving element 11 through the optical component 8. However, in the present embodiment, when the scanner mirror 13 is fixed and only the scanner mirror 12 is moved, the same as the distance measuring device that measures the distance of the one-dimensional area is used, so that the measurement target 3 In order to measure the distance to the object, one-dimensional coordinates (horizontal coordinates in the present embodiment) are sufficient, and two-dimensional coordinates are not required. By moving the scanner mirror 13 as in the present embodiment, it is possible to obtain the same effect as when the distance is measured by moving the one-dimensional light receiving element (9 shown in FIG. 1). Further, by adding angle information of the scanner mirror 13, a distance on a two-dimensional plane can be measured.

As described above, according to the present embodiment, the one-dimensional light receiving element 9 can be used as the light receiving element. Therefore, as the light receiving element, a distance measuring device (laser range sensor) shown in FIG. 5 is used. There is no need to use a simple two-dimensional light receiving element 11, and the configuration can be simplified. Further, according to the present embodiment, it is possible to measure the distance more accurately than by moving the one-dimensional light receiving element 9 and measuring the distance.

Further, as in the present embodiment, by synchronizing the scanner mirror 12 and the scanner mirror 14, when the secondary multiple reflection light (15 shown in FIG. 8) is reflected by the scanner mirror 14, Since an image is formed at a position shifted up and down on the light receiving element depending on the reflection position, it is not observed as a light receiving amount distribution on the one-dimensional light receiving element 9. Thereby, the influence of the secondary multiple reflection light can be removed, and therefore, according to the distance measuring device of the present embodiment, even if the measurement target 3 is one in which the secondary multiple reflection light is likely to occur, the measurement is performed. The distance to the target 3 can be accurately measured.

[Second Embodiment] FIG. 2 is a diagram showing a schematic configuration of a distance measuring apparatus according to a second embodiment of the present invention. 1, reference numeral 1 denotes a light source, 2 denotes a light beam emitted from the light source 1, 3 denotes an object to be measured, 7 denotes reflected light reflected on the surface of the object 3 to be measured, 8 denotes an optical component, 9 denotes a light receiving element, and 12 denotes a light receiving element. , 13 are scanner mirrors. The distance measuring apparatus according to the present embodiment includes the scanner mirror 12 of the second light emitting control unit of the first embodiment and the scanner mirror (third rotating mirror) 14 of the light receiving control unit of the first embodiment. The distance measuring apparatus according to the first embodiment is different from the distance measuring apparatus according to the first embodiment in that the distance measuring apparatus is integrally configured.
Even if the scanner mirror 12 and the scanner mirror 14 are integrally formed, the same operation and effect as those of the distance measuring device of the first embodiment can be obtained. However, in the distance measuring device of the present embodiment, the second light emitting control means (or the light receiving control means) of the first embodiment is replaced by the light receiving control means (or the second light emitting control means) of the first embodiment. ).

In each of the above embodiments, the case where the one-dimensional light receiving element 9 is used as the light receiving element has been described. However, the present invention is not limited to this, and the two-dimensional light receiving element (FIG. It is also possible to use 11) shown in FIG. Even when a two-dimensional light receiving element is used as the light receiving element, the secondary multiple reflected light (15 shown in FIG. 8)
When the light is reflected by the scanner mirror 12, the imaging position on the light receiving element changes depending on the reflection position. Here, in the case of the regular reflected light 7, an image is formed on a predetermined straight line, whereas in the case of the secondary multiple reflected light, an image is formed at a position distant from the straight line. Therefore, by examining the distribution of received light on a predetermined straight line on the two-dimensional light receiving element, only the distribution of received light of the regular reflected light can be observed. Furthermore, the straight line on which the regular reflected light forms an image may be in any position and orientation as long as it is on the two-dimensional light receiving element. Therefore, the regular reflected light necessary when using the one-dimensional light receiving element is used. There is no need to adjust the position so that an image is formed on the light receiving element.
As described above, even in the distance measuring devices of the above-described embodiments using the two-dimensional light receiving element as the light receiving element, the influence of the secondary multiple reflection light can be removed. Even if light easily occurs, the distance to the measurement target 3 can be accurately measured. As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Of course, it is.

[0019]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) According to the present invention, the scanner mirror on the light emitting side and the scanner mirror on the light receiving side are synchronized to reduce the influence of the secondary multiple reflected light, so that the secondary multiple reflected light is generated. It is possible to measure a distance with high accuracy for a measurement object having a shape that is easy to be formed and a glossy object that is likely to generate secondary multiple reflected light. (2) According to the present invention, the light beam from the light source is scanned by the two scanner mirrors in the X and Y axis directions on the light projecting side. Distance measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a distance measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a distance measuring device according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining the basic principle of a conventional laser range sensor.

FIG. 4 is a diagram for explaining the principle of distance measurement of a conventional laser range sensor.

FIG. 5 is a diagram showing a schematic configuration of a conventional laser range sensor.

FIG. 6 is a diagram illustrating an imaging position calculated from a received light amount distribution when there is no multiple reflected light.

FIG. 7 is a diagram illustrating an imaging position calculated from a received light amount distribution when there is multiple reflected light.

FIG. 8 is a diagram illustrating a state in which secondary multiple reflected light is generated as an example of multiple reflection.

FIG. 9 is a diagram illustrating an L-shaped measurement target as a measurement target in which secondary multiple reflected light is likely to be generated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Light beam, 3, 3a, 3b ... Measurement object, 7 ... Regular reflected light, 8 ... Optical parts, 9 ... Light receiving element,
10: light receiving surface of light receiving element, 11: two-dimensional light receiving element, 1
2, 13, 14: scanner mirror, 15: secondary multiple reflected light.

Claims (3)

[Claims] 1. A light source, a one-dimensional light receiving element for converting received light energy into an electric signal corresponding to the position and intensity of light, and a light beam emitted from the light source is reflected by a surface of an object to be measured. Imaging means for imaging the reflected light as a light spot on the light receiving surface of the light receiving element; and a first rotating mirror, and a light beam emitted from the light source by the first rotating mirror is provided on a first axis. A first light emitting control means for controlling the light beam in the first direction, and a second rotating mirror. The light beam controlled in the first axis direction by the first light emitting control means by the second rotating mirror is provided on the second axis. A second light emitting control means for controlling the direction of light, and a third rotating mirror synchronized with a second rotating mirror of the second light emitting control means, and the third light emitting mirror emits light from the light source. Formed at the position where the reflected light beam irradiates the measurement object Distance measuring apparatus comprising: a light receiving control means for controlling the imaging onto the one-dimensional light receiving element on the pot. 2. A light source, a two-dimensional light receiving element for converting received light energy into an electric signal corresponding to the position and intensity of light, and a light beam emitted from the light source is reflected by a surface of a measurement object. Imaging means for imaging the reflected light as a light spot on the light receiving surface of the light receiving element; and a first rotating mirror, and a light beam emitted from the light source by the first rotating mirror is provided on a first axis. A first light emitting control means for controlling the light beam in the first direction, and a second rotating mirror. The light beam controlled in the first axis direction by the first light emitting control means by the second rotating mirror is provided on the second axis. A second light emitting control means for controlling the direction of light, and a third rotating mirror synchronized with a second rotating mirror of the second light emitting control means, and the third light emitting mirror emits light from the light source. Formed at the position where the reflected light beam irradiates the measurement object Distance measuring apparatus comprising: a light receiving control means for controlling the imaging onto the two-dimensional light receiving element on the pot. 3. The second rotating mirror and the third rotating mirror are integrally formed, and the second light emitting control means (or the light receiving control means) is provided with the light receiving controlling means (or the light receiving control means). 3. The distance measuring apparatus according to claim 1, wherein the distance measuring apparatus also functions as two light projection control means.