JP4339165B2 - Light receiving center detection method, distance measuring device, angle measuring device, and optical measuring device - Google Patents

Description

  The present invention relates to a light receiving center detection method, a distance measuring device, an angle measuring device, and an optical measuring device.

  As a conventionally known optical measuring apparatus, it measures the distance and tilt angle of an object to be measured using the principle of triangulation, and includes a distance measuring optical system and an angle measuring optical system. In the distance measuring optical system, the light from the light projecting element converged by the lens is projected obliquely onto the object to be measured, and the reflected light is converged by the lens to form an image on the imaging surface of the imaging means. Has been. Then, the light receiving center position of the spot of the reflected light on the imaging surface is obtained based on the imaging signal corresponding to the received light amount for each pixel output from the imaging means, and based on the position displacement of the light receiving center position, The distance is to be measured.

In addition, the angle measuring optical system projects light from the light projecting element, which has been collimated by the lens, obliquely onto the object to be measured, and the reflected light is converged by the lens to be connected to the imaging surface of the imaging means. It is configured to image. Then, the light receiving center position of the spot of the reflected light on the imaging surface is detected based on the image pickup signal corresponding to the amount of light received for each pixel output from the image pickup means, and the light receiving center position is detected based on the position displacement of the light receiving center position. The tilt angle of the measurement object is measured.
JP-A-8-240408

  Here, there are a so-called sub-pixel method, a center of gravity method (volume center of gravity method, area center of gravity method) and the like as a light receiving center position detecting method in a conventional optical measuring apparatus. The sub-pixel method is a method in which a pixel having the highest received light amount level is specified based on an imaging signal from an imaging unit, and the position of the pixel is determined as a light receiving center position. The volume centroid method is a method of determining a volume centroid position calculated by applying the following formula to an imaging signal indicating a received light amount level equal to or greater than a predetermined threshold among imaging signals from the imaging means as a light receiving center position. .

<Formula 1>
Volume centroid position = {Σ (mI) / Σm}
I: Same as in the case of the area centroid position m: Coefficient according to the light reception level of each pixel

  By the way, in the optical measuring apparatus, for example, the light projection optical axis from the light projecting element is shaken due to vibration from the outside, the light projection state is changed by the operation of APC (Auto Power Control) for the light projecting element, The reflection state may change due to the displacement of the position of the measurement object. Due to these factors, the spot of reflected light (hereinafter referred to as “light receiving spot”) imaged on the imaging surface of the imaging means may be shaken or fluctuated (for example, the shape of the light receiving spot or the distribution of received light amount varies). . Therefore, as in the conventional configuration, in the sub-pixel method or the center-of-gravity method based on one threshold value, the measurement result differs for the object to be measured having the same distance and inclination angle according to the variation in the shape of the light receiving spot. There was a risk of it. In particular, since the optical measurement device is used to measure a minute distance displacement and tilt angle displacement, variations in the spot shape and the like greatly affect the measurement.

  The present invention has been completed based on the above circumstances, and a light receiving center detection method, distance, and distance that can obtain a more accurate measurement result even when the light receiving spot is shaken or fluctuated. An object is to provide a measuring device, an angle measuring device, and an optical measuring device.

As a means for achieving the above object, the light receiving center detecting method according to the first aspect of the present invention causes the light emitted from the light projecting means to be received by the imaging surface of the imaging means, and is output from the imaging means to output the imaging. A light receiving center detection method for detecting a light receiving center position on the imaging surface based on an imaging signal corresponding to an amount of light received for each pixel on the surface, wherein each pixel is detected based on an imaging signal from the imaging means. The received light amount level is compared with each of a plurality of thresholds having different levels, and for each of the threshold values, an extraction process for extracting a pixel group having a received light amount level equal to or greater than the threshold value, and the center of gravity position detection process of detecting the center of gravity position (centroid position or volume barycentric position), respectively, based the extracted by the threshold to the amount of received light level of the pixel groups, detected by the gravity center position detection processing And performing the determination process for determining a plurality of averaged center position of the center of gravity position as the light receiving center position as a.

A distance measuring device according to a second aspect of the present invention is a distance measuring light projecting means for projecting light on a measured object, and light reflected from the distance measuring light projecting means and diffusely reflected or specularly reflected by the measured object. A converging lens that converges the reflected light, and a distance measuring imaging unit that receives light passing through the converging lens on an imaging surface and outputs an imaging signal corresponding to the amount of received light for each image on the imaging surface; A light receiving center detecting means for detecting a light receiving center position of the reflected light on the image pickup surface based on an image pickup signal output from the distance measuring image pickup means, and from the distance measuring light projecting means to be measured. The light projecting optical path to the object and the reflected light path from the object to be measured to the distance measuring imaging unit are configured to form a predetermined angle, and based on the light receiving center position detected by the light receiving center detecting unit Object to be measured In the distance measuring device for measuring a distance, the light receiving center detecting means compares the received light amount level at each pixel with a plurality of thresholds having different levels from each other based on an imaging signal from the distance measuring imaging means, for each of these thresholds, an extraction means for extracting a pixel group at the threshold value or more in the amount of received light level, the center of gravity position based the on the light receiving amount level of the pixel groups extracted by the threshold values in the extraction unit Centroid position detection means for detecting (area centroid position or volume centroid position), and determination means for determining a center position obtained by averaging the plurality of centroid positions detected by the centroid position detection means as the light receiving center position. Are characterized by comprising the above.

The invention according to claim 3, in the distance measuring apparatus according to claim 2, wherein the plurality of threshold values, there is the distance detectable minimum light receiving quantity level or at the measuring pickup means, said distance measuring image pickup means Threshold value setting means for setting in a range lower than the maximum received light amount level on the imaging surface is provided.

An angle measuring apparatus according to a fourth aspect of the invention includes an angle measuring light projecting unit that projects light onto a measured object, and reflected light that is projected from the angle measuring light projecting unit and regularly reflected by the measured object. A converging lens that converges the light, light that has passed through the converging lens is received by the imaging surface, and an imaging device for angle measurement that outputs an imaging signal corresponding to the amount of light received for each image on the imaging surface, and the angle measurement A light receiving center detecting means for detecting a light receiving center position of the reflected light on the imaging surface based on an imaging signal output from the image pickup means, and based on the light receiving center position detected by the light receiving center detecting means. In the angle measuring device for measuring the tilt angle of the object to be measured, the light receiving center detecting means sets the received light amount level at each pixel based on the imaging signal from the angle measuring imaging means. of Compared with the values respectively for each of those thresholds, and extracting means for extracting a pixel group was the threshold value or more in the amount of received light level, the light receiving amount of each pixel group the extracted by the threshold values in the extraction unit A center-of-gravity position detection unit that detects a center-of-gravity position (area center-of-gravity position or volume center-of-gravity position) based on the level, and a center position obtained by averaging the plurality of center-of-gravity positions detected by the center-of-gravity position detection unit And determining means for determining as a feature.

A fifth aspect of the present invention, the angle measuring device according to claim 4, wherein the plurality of threshold values, the there is at an angle measuring imaging means capable of detecting a minimum received light quantity level above, the angle measuring image pickup means Threshold value setting means for setting in a range lower than the maximum received light amount level on the imaging surface is provided.

An optical measuring apparatus according to a sixth aspect of the present invention is an optical measuring apparatus that irradiates a measured object with light and measures the tilt angle and distance of the measured object based on the reflected light. An angle measurement light projecting unit that irradiates light as substantially parallel light toward the light, and a converging lens that converges the reflected light for angle measurement that is projected from the angle measurement light projecting unit and regularly reflected by the measured object; An imaging unit that receives light passing through the convergent lens on an imaging surface and outputs an imaging signal corresponding to the amount of light received for each image on the imaging surface, and an irradiation direction of light from the angle measuring light projecting unit A distance measuring light projecting means arranged to irradiate the object to be measured with light as substantially parallel light from a direction inclined at a predetermined angle with respect to the object, and the object to be measured projected from the distance measuring light projecting means Reflected light for distance measurement diffusely or specularly reflected by A converging lens for converging, an imaging unit that receives light that has passed through the converging lens on an imaging surface, and outputs an imaging signal corresponding to the amount of light received for each image on the imaging surface, and is output from the imaging unit A light receiving center detecting means for detecting a light receiving center position of each of the reflected light for angle measurement and the reflected light for distance measurement on the imaging surface based on an imaging signal, and detected by the light receiving center detecting means. In the optical measuring device that measures the tilt angle and distance of the object to be measured based on the light receiving center position, the light receiving center detecting unit is configured to detect the angle measuring reflected light and the distance measuring reflected light from the imaging unit. The received light level at each pixel is compared with each of a plurality of thresholds having different levels based on the imaging signal, and the received light amount level equal to or higher than the threshold is determined for each threshold. Extraction means for extracting a group of pixels were Le, respectively detected gravity center position (the centroid position or volume centroid position) based the light-receiving amount level of the pixel groups extracted by the threshold values in the extraction unit The center of gravity position detecting means, and a determining means for determining, as the light receiving center position, a center position obtained by averaging the plurality of center of gravity positions detected by the center of gravity position detecting means. .

  In the configuration of claim 6, the “converging lens”, “imaging unit”, and “light receiving center detection unit” may be different for angle measurement and distance measurement, or may be common.

Further, the configuration of claim 6 includes the following.
<Configuration A> “An optical measurement device that irradiates light to an object to be measured and measures the tilt and distance of the object to be measured based on the reflected light,
A light projection means for angle measurement used for angle measurement;
A distance measuring projection means used for distance measurement;
A collimator lens that changes light from the angle measurement light projecting means and the distance measurement light projecting means into substantially parallel light;
Light from the angle measuring light projecting means and the distance measuring light projecting means, which is arranged closer to the angle measuring light projecting means and the distance measuring light projecting means than the collimator lens. A branching unit that guides the reflected light from the measured object in a direction different from the angle measuring light projecting unit and the distance measuring light projecting unit side while guiding the measured object in the direction;
A converging lens for converging the specularly reflected light;
The regular reflection light (angle measurement regular reflection light) by the light from the angle measurement light projecting means out of the regular reflection light converged by the convergent lens is received by the imaging surface, and each pixel on the imaging surface is received. Imaging means for angle measurement that outputs an imaging signal corresponding to the amount of received light;
Of the specularly reflected light converged by the converging lens, specularly reflected light (distance measuring specularly reflected light) from the distance measuring light projecting means is received by the imaging surface, and each pixel on the imaging surface is received. Distance measuring imaging means for irradiating distance measuring regular reflection light for outputting an imaging signal corresponding to the amount of received light;
Based on the imaging signal output from the angle measurement imaging means, an angle measurement light receiving center detection means for detecting a light reception center position of the angle measurement reflected light on the imaging surface;
Based on the imaging signal output from the distance measuring imaging means, a distance measuring light receiving center detecting means for detecting a light receiving center position of the distance measuring reflected light on the imaging surface;
The tilt angle of the object to be measured is measured based on the light receiving center position detected by the angle measuring light receiving center detecting means, and detected by the angle measuring light receiving center detecting means and the distance measuring light receiving center detecting means, respectively. Measuring means for measuring the distance to the object to be measured based on the received light receiving center position,
An optical measuring device arranged such that an optical path from the distance measuring light projecting means to the object to be measured has a predetermined angle with respect to a base axis,
The angle measuring light receiving center detecting means and the distance measuring light receiving center detecting means are configured to detect the reflected light (angle measuring reflected light and distance measuring reflected light) corresponding to the reflected light (angle measuring imaging means). The received light amount level at each pixel is compared with each of a plurality of threshold values having different levels based on the image pickup signal from the distance measuring image pickup means), and the received light amount level is equal to or higher than the threshold value for each threshold value. An extraction means for extracting the pixel group that was present;
Centroid position detection means for detecting a centroid position (area centroid position or volume centroid position) based on the received light amount level of each pixel group extracted by each threshold in the extraction means;
An optical measuring apparatus comprising: a determining unit that determines a center position obtained by averaging the plurality of barycentric positions detected by the barycentric position detecting unit as the light receiving center position. "

  A seventh aspect of the present invention is the optical measurement apparatus according to the sixth aspect, wherein the plurality of threshold values are equal to or higher than a minimum received light amount level that can be detected by the imaging unit, and are the maximum on the imaging surface of the imaging unit. Threshold setting means for setting in a range below the received light level is provided.

<Invention of Claims 1, 2, 4 and 6>
According to this configuration, the received light amount level at each pixel on the imaging surface of the image sensor is compared with each of a plurality of threshold values having different levels, and the received light amount level is equal to or higher than the threshold value for each threshold value. The center of gravity of each pixel group (area centroid position or volume centroid position) is detected, and the center position obtained by averaging these centroid positions is used as the light receiving center position of the light receiving spot on the imaging surface. decide.
In this way, by obtaining a center position averaged from a plurality of barycentric positions based on a plurality of thresholds having different levels, it is possible to obtain an accurate measurement result by suppressing measurement errors due to shaking and fluctuations in the light receiving spot. .

<Invention of Claims 3, 5 and 7>
According to this configuration, the plurality of threshold values can be freely set by the threshold setting unit within a range that is equal to or higher than the minimum light reception level that can be detected by the imaging unit and lower than the maximum light reception level on the imaging surface of the imaging unit. Therefore, it is possible to set an appropriate threshold value for the characteristics of shaking and fluctuation of the light receiving spot.

<Embodiment 1>
A first embodiment corresponding to claims 1 to 3 of the present invention will be described with reference to FIGS.

1. Configuration of the present embodiment (1) Overall configuration Reference numeral 20 denotes a laser light source for distance measurement, to which a laser drive circuit 21 is connected. The laser driving circuit 21 supplies a driving current Ib to the distance measuring laser light source 20 based on a control signal Sa from the CPU 11 to perform a lighting operation. The distance measuring laser light source 20 can be driven intermittently or continuously.

  The distance measurement laser light L emitted from the distance measurement laser light source 20 is converted into parallel light through the collimator lens 22 (the distance measurement laser light source 20 and the collimator lens 22 are the “light projection means” of the present invention, It constitutes "distance measuring light projecting means"). The arrangement positions of the distance measuring laser light source 20 and the collimator lens 22 are adjusted so that the parallel light is incident on the surface of the measured object W in the reference posture from an oblique direction. That is, the distance measuring laser beam L is incident at an incident angle θ degree (> 0 degree) (therefore, “the light projecting optical path from the distance measuring projecting means to the object to be measured and the object to be measured” To the reflected light path from the distance measuring light receiving means to form a predetermined angle ”).

  The specularly reflected light L ′ of the distance measuring laser light L on the surface of the workpiece W (object to be measured) is converged by a converging lens 23 arranged in a line-symmetrical position with respect to the collimator lens 22, and an image sensor 24 (imaging means, Irradiated on the imaging surface of the distance measuring imaging means). Hereinafter, the irradiation image of the regular reflection light L ′ is referred to as a “light receiving spot”.

The converging lens 23 is arranged so that the focal position F of the regular reflection light L ′ that has passed through the converging lens 23 is located in front of the imaging surface of the imaging device 24. Here, the reason why the condensing position of the regular reflection light L ′ is not matched with the imaging surface of the image sensor 24 is that the position of the light receiving spot of the regular reflection light L ′ on the imaging surface according to the distance of the work W is determined. This is because the distance of the workpiece W is calculated from the light receiving center position of the light receiving spot as will be described later. Therefore, the condensing position F of the regular reflection light L ′ may be configured to be located behind the imaging surface of the imaging device 24.
The focusing position of the regular reflection light L ′ is adjusted by moving the convergence lens 23 along the optical path of the regular reflection light L ′ or by replacing the convergence lens 23 with another convergence lens having different characteristics. Can do.

(2) Processing in CPU for Distance Measurement The imaging element 24 transmits to the CPU 11 an imaging signal Sb composed of a digital signal sequence corresponding to the light receiving spot of the regular reflection light L ′ formed on the imaging surface. The CPU 11 supplies the control signal Sa to the laser drive circuit 21 described above to turn on the distance measuring laser light source 20 in pulses. Further, the CPU 11 captures the imaging signal Sb from the imaging device 24 in synchronization with the transmission of the control signal Sa, and detects the light receiving center position N of the light receiving spot on the imaging surface of the regular reflection light L ′ for distance measurement based on this. For example, the distance from the convergent lens 23 to the workpiece W is measured. This light receiving center detection process will be described in detail later.

(3) Distance measurement In this embodiment, the distance of the workpiece W is measured using the principle of triangulation.
First, based on the imaging signal Sb transmitted from the imaging device 24 in synchronization with the lighting operation of the distance measuring laser light source 20, the light receiving center position N is detected by a light receiving center detection process described later. Then, the distance of the workpiece W is measured from the separation interval between the light receiving center position N and the reference position O in the image sensor 24.

More specific description will be given below.
For example, when in the position of A in 1 measured object W in FIG. (Distance d1), the light receiving center position is formed on the imaging surface of the image sensor 24 at the time of lighting operation of the distance measuring laser light source 20 N1 Is away from the reference position O by d1 ′ (not shown in the figure because the light receiving center position N1 and the reference position O coincide with each other), and based on this, the distance d1 is measured.

When the object to be measured W is at the position B (distance d2) in FIG. 1 (refer to FIGS. 2 and 4 for details), it is formed on the imaging surface of the image sensor 24 when the distance measuring laser light source 20 is turned on. Since the received light receiving center position N is separated from the reference position O by d2 ′, this is measured as the distance d2.
When the workpiece W is at the position C (distance d3, tilt angle θ1 degree) in FIG. 1 (see FIGS. 3 and 4 for details), the imaging surface of the image sensor 24 is turned on when the distance measuring laser light source 20 is turned on. Since the light receiving center position N formed on the upper side is separated from the reference position O by d3 ′, the distance is measured as d3.

2. Light receiving center detection process As described above, the light projecting optical axis from the light projecting element is shaken due to external vibration, or the light projecting state is changed by the operation of APC (Auto Power Control) for the light projecting element. The reflection state may change due to the displacement of the position of the object to be measured. Due to these factors, the light receiving spot on the imaging surface of the imaging means may be shaken or fluctuated (for example, the shape of the light receiving spot or the distribution of received light amount varies) (see the left figure in FIG. 5). This embodiment, in order to cope with such problems, CP U 11 executes a receiving center detection process shown in the flowchart of FIG.

  When the CPU 11 takes in the image signal Sb from the image sensor 24, the CPU 11 executes the control shown in FIG. First, in step S1, a pixel group (hereinafter referred to as “first pixel group G1”) indicating a received light amount level equal to or higher than the first threshold Th1 is extracted. Next, in step S2, a pixel group (hereinafter referred to as “second pixel group G2”) indicating a received light amount level equal to or higher than a second threshold Th2 smaller than the first threshold is extracted. Further, in step S3, a pixel group (hereinafter referred to as “third pixel group G3”) having a light reception amount level equal to or higher than a third threshold Th3 that is smaller than the second threshold is extracted. Therefore, at this time, the CPU 11 functions as the “extraction means” of the present invention.

  Next, in step S4, the area centroid positions P1, P2, and P3 are calculated by applying the following Expression 2 to each of the first pixel group G1, the second pixel group G2, and the third pixel group G3. Accordingly, at this time, the CPU 11 functions as the “center of gravity position detecting means” of the present invention.

<Formula 2>
Area centroid position = {Σ (MI) / ΣM}
I: Position vector of each pixel in the Kth (threshold number K = 1, 2, 3) pixel group M: Number of the Kth pixel group

  In step S5, the center position (X, Y) obtained by averaging the area centroid positions P1 (x1, y1), P2 (x2, y2), and P3 (x3, y3) by applying Expression 3 shown below. The center position (X, Y) is calculated and determined as the light receiving center position N of the light receiving spot. Therefore, at this time, the CPU 11 functions as the “determination means” of the present invention.

<Formula 3>
Center position (X, Y)
X = (x1 + x2 + x3 + ...) / K
Y = (y1 + y2 + y3 + ...) / K
Note that, for each of the first pixel group G1, the second pixel group G2, and the third pixel group G3, the following formula 4 may be applied to calculate the volume centroid positions P1, P2, and P3 (see FIG. 7) .

<Formula 4>
Volume centroid position = {Σ (mI) / Σm}
I: Same as Equation 2 m: Coefficient according to the light reception level of each pixel

  The volume centroid method according to Equation 4 can calculate the centroid position in each pixel group more accurately. For example, when the workpiece W is a specular reflector, the received light amount level of the pixels in the light receiving spot is set. Is almost uniform, and even the area centroid method according to Equation 3 can calculate the centroid position with the same accuracy as the volume centroid method according to Equation 4. Therefore, in such a case, by adopting the area centroid method according to Equation 3, it is possible to reduce the processing load of the light receiving center detection processing and to achieve high speed processing.

  Each of the first to third threshold values Th1, Th2, Th3 is equal to or higher than the minimum received light amount level (dark cut level) that can be detected by the image sensor 24 in the threshold setting unit 12 (shown only in FIG. 1) connected to the CPU 11. Thus, it can be set to be changeable within a range that is lower than the maximum received light amount level on the imaging surface of the imaging device 24. In the present embodiment, the level lower than the maximum received light amount level is lower than the maximum received light amount level by a predetermined percentage (%). Therefore, by starting the distance measuring device and setting the maximum received light amount level based on the imaging signal Sb from the image sensor 24 before setting the threshold, a level lower than the maximum received light amount level can be set. In the threshold setting unit 12, the number of thresholds can also be changed.

3. Advantages of the present embodiment (1) The left diagram of FIG. 5 shows two patterns of received light amount level distributions V 1 and V 2 due to blurring and fluctuations in the light receiving spot. Here, when the area centroid position is calculated by one threshold value, for example, the first threshold value Th1, as in the prior art, and this is used as the light receiving center position of the light receiving spot, as shown in the right diagram of FIG. In the pattern, the light receiving center position may deviate greatly from P1 (x1, y1) and P1 ′ (x1 ′, y1 ′). Similarly, the above-described subpixel method may cause a large shift.
On the other hand, in the present embodiment, the area gravity center positions P1, P2, and P3 (P1 ′, P2 ′, and P3 ′) are calculated based on the first to third threshold values Th1, Th2, and Th3, respectively, and these are averaged. The center position thus obtained is determined as the light receiving center position N (N ′). Therefore, it is possible to suppress the positional deviation of the light receiving center position N due to the shake or fluctuation of the light receiving spot as much as possible, and it is possible to perform accurate distance measurement.

  (2) Further, in the present embodiment, the threshold level setting unit 12 is at least the minimum received light amount level (dark cut level) that can be detected by the image sensor 24 and is the maximum received light amount level on the imaging surface of the image sensor 24. It can be changed freely within the range below the lower level. Therefore, it is possible to set an appropriate threshold value for the characteristics of shaking / fluctuation of the light receiving spot.

<Embodiment 2>
A second embodiment of the distance measuring device will be described with reference to FIGS. In addition, about the part same as Embodiment 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
In the present embodiment, after the light from the distance measuring laser light source 20 is converted into parallel light by the collimator lens 22, the parallel light is irradiated onto the work W, and the diffuse reflected light LD on the surface of the work W is applied to the convergence lens 23. Thus, the light is condensed and irradiated onto the image pickup surface of the image pickup device 24.
The imaging element 24 is disposed behind the condensing position P of the diffusely reflected light that has passed through the converging lens 23 and converted into converging light, and transmits the diverging light through the converging lens 23. The imaging surface of the imaging element 24 is irradiated.

  As shown in FIG. 8 to FIG. 11, the irradiation position of the diffuse reflected light LD on the imaging surface of the image sensor 24 is arranged at a position that matches the condensing position of the reflected light LD in the optical path of the reflected light LD. Compared to the case, the position is shifted in the direction intersecting the reflected light path. Further, the direction of deviation is a direction away from the optical axis with the reflected light path as the center. In short, by disposing the image pickup device 24 behind the condensing position of the diffusely reflected light LD along the reflected light path, the amount of deviation of the irradiation position is amplified. With this configuration, the resolution (measurement accuracy) in distance measurement can be improved.

  Even in such a configuration, the same effect as that of the first embodiment can be obtained by applying the light receiving center detection process (FIG. 6) of the first embodiment to the detection of the light receiving center.

<Embodiment 3>
An embodiment of an angle measuring device according to claims 1, 4 and 5 will be described with reference to FIG.
The angle measuring device 50 according to the present embodiment measures the tilt angle of the workpiece W using an autocollimator method.
The light from the light projecting element 51 (angle measuring light projecting means) is converted into parallel light by the collimator lens 52, and this parallel light is reflected by the half mirror 53 to the direction of the workpiece W located on the optical axis LC. Lead. The parallel light irradiated to the workpiece W is regularly reflected and transmitted through the half mirror 53, and is condensed by the converging lens 54 onto the imaging surface 55A of the imaging element 55 (angle measuring imaging means). . The image signal Sa from the image sensor 55 is output to the CPU 56.

  The CPU 56 gives the control signal Sb to the light projecting element 51 to emit light, and gives the control signal Sc to the image pickup element 55 and drives it at a timing synchronized therewith to receive the image pickup signal Sa. Then, the CPU 56 detects the light receiving center position N of the irradiated image (light receiving spot) on the imaging surface 55A of the regular reflection light L specularly reflected on the workpiece W, based on the received imaging signal Sa. Since the light receiving center position N is displaced according to the change in the tilt angle of the work W, the tilt angle of the work W can be measured from the positional deviation between the light receiving center position N and the origin O at the center of the imaging surface 55A, for example. It becomes possible. Note that the present embodiment also includes a threshold setting unit 57 similar to the threshold setting unit 12 of the first embodiment.

  Here, also in the present embodiment, the same effect as that of the first embodiment can be obtained by applying the light receiving center detection process (see FIG. 6) described in the first embodiment in detecting the light receiving center position.

<Embodiment 4>
Embodiment 4 of the optical measuring device according to claims 1 and 6 (configuration A described above) and 7 of the present invention will be described with reference to FIGS.

1. Configuration of Optical Measuring Device In the present embodiment, the tilt angle and distance of the workpiece W are measured, and the configuration is as shown in FIG. Light emitted from the angle measuring laser light source 111 and the distance measuring laser light source 121 is transmitted through a dichroic mirror 131 (light converging means), a beam splitter 132 and a collimator lens 133 (corresponding to a collimator lens and a converging lens). The object to be measured) is irradiated with both lights, and the specularly reflected light is passed through a collimator lens 133, a beam splitter 132, and a dichroic mirror 134 (light splitting dichroic mirror), for example, an angle measuring image pickup device 112 (for example, a two-dimensional CCD). (Illumination means for angle measurement) and an image pickup surface of a distance measurement image pickup element 122 (distance measurement image pickup means) that is also a two-dimensional CCD, and the CPU 104 tilts the workpiece W based on the irradiation position (light receiving center position). And the distance are calculated. The surface of the workpiece W may be a mirror surface or a non-mirror surface.

  Both laser light sources 111 and 121 emit light having different wavelengths, for example, the angle measuring laser light source 111 emits laser light having a wavelength λ1, while the distance measuring laser. The light source 121 emits laser light having a wavelength λ2. Laser drive circuits 113 and 123 are connected to the laser light sources 111 and 121, respectively, and drive currents Ia and Ib are supplied to the laser light sources 111 and 121 based on control signals Sa and Sb from the CPU 104, respectively. (An angle measuring light source 111 and a laser driving circuit 113 constitute an angle measuring light projecting means, and a distance measuring laser light source 121 and a laser driving circuit 123 constitute a distance measuring light projecting means). The laser light sources 111 and 121 can be driven intermittently or continuously.

  The dichroic mirror 131 is configured to transmit light having a wavelength λ1 and reflect light having a wavelength λ2, so that the laser light of the angle measuring laser light source 111 passes through the dichroic mirror 131 and is beam splitter. The light from the distance measuring laser light source 121 is reflected by the dichroic mirror 131 and travels toward the beam splitter 132.

  Further, the laser light from the angle measuring laser light source 111 is incident on the incident surface of the dichroic mirror 131 perpendicularly, and the laser light from the distance measuring laser light source 121 is incident obliquely on the incident surface of the dichroic mirror 131. (Corresponding to a configuration in which the distance measuring light projecting unit is arranged so that light from the distance measuring light projecting unit is obliquely irradiated to the object to be measured). Thus, the light axis of the angle measuring laser light source 111 is made parallel to the optical axis (base line axis) LC (L′ C ′) of the optical system, and the light axis of the distance measuring laser light source 121 is the light of the optical system. The state is inclined with respect to the axis LC (L′ C ′).

  The laser light reflected from the beam splitter 132 is converted into parallel light by the collimator lens 133 and is irradiated onto the workpiece W. At this time, the laser beam from the angle measurement laser light source 111 is irradiated perpendicularly to the surface of the workpiece W when the workpiece W is in an attitude without tilting, whereas the laser beam for distance measurement is used. Since the laser light from the laser light source 121 is inclined with respect to the optical axis LC (L′ C ′) of the optical system, the light is irradiated obliquely onto the surface of the workpiece W. The spot diameter of the laser light irradiated onto the workpiece W is smaller in the laser light from the laser light source 121 than in the laser light from the laser light source 111, and the laser light from the laser light source 121 is the laser light from the laser light source 111. Irradiation is within the irradiation range.

  The specularly reflected light from the workpiece W is collected by the collimator lens 133, and is specularly reflected by the angle measuring laser light source 111 (the specularly reflected light for angle measurement) by the dichroic mirror 134 having the same characteristics as the dichroic mirror 131. ) Forms an image on the imaging surface of the angle measurement imaging device 112 to form a light receiving spot. Further, the regular reflection light (distance measurement regular reflection light) from the distance measurement laser light source 121 is reflected by the dichroic mirror 134 and applied to the imaging surface of the distance measurement image sensor 122. Since the imaging surface of the distance measuring image sensor 122 is disposed behind the focal position F of the specularly reflected light, a light image having a predetermined size is formed on the imaging surface. Here, the reason why the imaging surface of the distance measuring image sensor 122 is not coincident with the focal position F is that the optical path to the focal position F changes according to the distance of the workpiece W. This is because the distance of the workpiece W can be calculated.

  The angle measuring image sensor 112 and the distance measuring image sensor 122 transmit to the CPU 104 image signals Sc and Sd that are digital signal sequences corresponding to the positions of the respective light receiving spots formed on the imaging surface.

  The CPU 104 transmits the control signals Sa and Sb to the laser drive circuits 13 and 23 described above, captures the imaging signal Sc from the angle measurement imaging device 112 in synchronization with the transmission of the control signal Sa, and transmits the control signal Sb. The image pickup signal Sd from the distance measuring image pickup element 122 is captured in synchronization with the above. Then, the inclination of the workpiece W and the distance from the collimator lens 133 to the workpiece W are measured based on the imaging signals Sc and Sd. Note that this embodiment also includes a threshold setting unit 136 similar to the threshold setting unit 12 of the first embodiment.

2. Operation of the present embodiment The configuration of the present embodiment is as described above. Next, the operation will be described.
(1) Inclination detection In this embodiment, the inclination is measured by using a well-known autocollimation method. Here, the light reception center detection process of FIG. The position is detected, and the tilt direction and tilt angle of the workpiece W are calculated based on the light receiving center position.

(2) Distance measurement In the distance measurement, first, the angle of the workpiece W is detected by the above-described inclination measurement. Then, based on the imaging signal Sd from the distance measuring imaging element 122, the process shown in FIG. 6 described in the first embodiment is executed to detect the light receiving center position (center of gravity position). And it correct | amends based on the inclination calculated by inclination measurement, and calculates the distance of the workpiece | work W from the distance and direction of the said gravity center position and a reference | standard position.

  For example, when the workpiece W is at the position (1) (distance d1, inclination angle 0) in FIG. 13 (see FIG. 14 for details), the light receiving spot formed on the imaging surface of the angle measuring image sensor 112. Since the position S1 coincides with the reference position Ra, the inclination angle is measured as 0 °. Further, since the optical image L1 on the imaging surface of the distance measuring image sensor 122 is d1 'away from the reference position Rb, the distance d1 is measured based on this.

  When the workpiece W is at the position (2) (distance d2, inclination angle 0) in FIG. 13 (see FIG. 15 for details), the condensing spot (on the imaging surface of the angle measuring image sensor 112) ( Since the position S2 of the light receiving spot) coincides with the reference position Ra, the inclination angle is measured as 0 °. Further, since the optical image L2 on the imaging surface of the distance measuring image sensor 122 is d2 'away from the reference position Rb, this is measured as the distance d2.

  When the workpiece W is at the position (3) in FIG. 13 (distance d2, inclination angle θ1) (see FIG. 16 for details), the position of the light receiving spot formed on the imaging surface of the angle measuring image sensor 112. Since S3 is separated from the reference position Ra by the distance d, the inclination angle θ1 is measured based on this distance. Further, the optical image L3 on the imaging surface of the distance measuring image sensor 122 is separated from the reference position Rb by d3 '. Here, since the workpiece W is inclined at the position (3), the optical image L3 formed on the imaging surface of the distance measuring image sensor 122 is formed at a position different from the optical image L2 at the position (2). Is done. Accordingly, since the CPU 104 calculates the distance by performing correction based on the inclination angle θ1, the distance is eventually measured as d2.

  According to the present embodiment, since the distance and the inclination are measured based on the regular reflection light from the work W, the inclination and the distance of the work W are measured regardless of the specular body or the non-specular body. It can be performed. In addition, the laser light sources 111 and 121 are configured to emit light having different wavelengths, and the laser light is separated by the dichroic mirrors 131 and 134 so that the imaging surfaces of the imaging elements 112 and 122 are irradiated. Since it is configured, laser light is not erroneously irradiated.

  In the present embodiment, the spot diameter of the laser light applied to the workpiece W is set so that the laser light 121 of the laser light source 121 is smaller than the laser light of the laser light source 111, and the laser of the laser light source 121 is used. The configuration is such that the light is irradiated within the laser light irradiation range of the laser light source 111, so that the irradiation position (measurement position) of the laser light on the workpiece W is substantially constant regardless of the distance and inclination of the workpiece W. can do.

  In the above configuration, a laser beam having the same wavelength may be emitted from both laser light sources 111 and 121. In this case, the control signals Sa and Sb are supplied from the CPU 104 to the laser drive circuits 113 and 123 so that the laser light sources 111 and 121 are alternately turned on, and a beam splitter is disposed in place of the dichroic mirrors 131 and 134, for example. You just have to do it. Further, as described above, the CPU 104 transmits the control signals Sa and Sb to the laser drive circuits 113 and 123, and captures the image pickup signal Sc from the angle measurement image pickup device 112 in synchronization with the transmission of the control signal Sa. The imaging signal Sd from the distance measuring image sensor 122 is captured in synchronization with the transmission of Sb. The tilt of the workpiece W and the distance from the collimator lens 133 to the workpiece W are measured based on the imaging signals Sc and Sd. If it does in this way, for example, a laser beam will be radiate | emitted alternately, interference of light will be suppressed and the effect that a measurement precision improves will be acquired.

  Further, as shown in FIG. 17, a configuration may be adopted in which a diverging lens 135 is disposed in front of the distance measuring image pickup element 122 so that specularly reflected light from the work W once condensed is diverged. In this way, since the optical image formed on the imaging surface is made larger, the amount of movement of the optical image when the workpiece W is displaced is increased, resulting in improved resolution and high-precision measurement. be able to. Further, it is more desirable to irradiate the peripheral portion of the diverging lens 135 with the regular reflection light. This is because the aberration is larger in the peripheral portion than in the central portion of the lens 135, and the specularly reflected light is further diverged, so that it can be measured with extremely high accuracy.

  Even in such a configuration, the same effect as that of the first embodiment can be obtained by applying the light receiving center detection process (FIG. 6) of the first embodiment to the detection of the light receiving center.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings, and various modifications can be made without departing from the scope of the invention.

The schematic diagram which showed the whole structure of the distance measuring device which concerns on Embodiment 1. FIG. Schematic showing work position and reflected light path Schematic showing work position and reflected light path Schematic showing work position and reflected light path Schematic diagram showing the relationship between received light level distribution and barycentric position by area barycentric method Flow chart showing light receiving center detection processing Schematic diagram showing the relationship between the received light level distribution and the center of gravity position by the volume center of gravity method The schematic diagram which showed the whole structure of the distance measuring device which concerns on Embodiment 2. FIG. Schematic showing work position and reflected light path Schematic showing work position and reflected light path Schematic showing work position and reflected light path The schematic diagram which showed the whole structure of the angle measuring device which concerns on Embodiment 3. FIG. The schematic diagram which showed the whole structure of the optical measuring device which concerns on Embodiment 4. FIG. Schematic showing work position and reflected light path Schematic showing work position and reflected light path Schematic showing work position and reflected light path Schematic diagram showing a modification of the fourth embodiment

Explanation of symbols

12, 57, 136... Threshold setting unit (threshold setting means 13, 23... Laser driving circuit 20, 121... Distance measuring laser light source 21... Laser driving circuit 23, 54. Imaging means)
50 ... Angle measuring device 51, 111 ... Projecting element (angle measuring light projecting means)
53. Half mirror (branching means)
55... Imaging device (imaging means, imaging means for angle measurement)
55A ... Imaging surface 112 ... Angle measurement imaging device (angle measurement imaging means)
113, 123 ... laser drive circuit 131, 134 ... dichroic mirror (branching means)
122. Image sensor for distance measurement (image sensor for distance measurement)
132 ... Beam splitter (branching means)
133 ... Collimator lens 134 ... Dichroic mirror 104 ... CPU (light receiving center detecting means, extracting means, barycentric position detecting means, determining means)
G1 to G3: Pixel group N: Light receiving center position W: Workpiece (object to be measured)

Claims (7)

The light emitted from the light projecting means is received on the imaging surface of the imaging means, and the light receiving on the imaging surface is output based on the imaging signal output from the imaging means and corresponding to the amount of light received for each pixel on the imaging surface. A light receiving center detection method for detecting a center position,
A pixel group in which the received light level at each pixel is compared with each of a plurality of thresholds having different levels based on an imaging signal from the imaging means, and the received light level is equal to or higher than the threshold for each of the thresholds. Extraction process to extract
And the center of gravity position detection process of detecting each position of the center of gravity based the on the light receiving amount level of the pixel groups extracted by the threshold values in the extraction process,
And a determination process of determining a center position obtained by averaging a plurality of the gravity center positions detected by the gravity center position detection process as the light reception center position. Distance measuring light projecting means for projecting light on the object to be measured;
A converging lens that converges reflected light that is projected from the distance measuring light projecting means and diffusely or specularly reflected by the measured object;
Distance measuring imaging means for receiving light that has passed through the convergent lens on an imaging surface and outputting an imaging signal corresponding to the amount of light received for each image on the imaging surface;
A light receiving center detecting means for detecting a light receiving center position of the reflected light on the image pickup surface based on an image pickup signal output from the distance measuring image pickup means, and from the distance measuring light projecting means to be measured. A light projecting optical path to an object and a reflected light path from the object to be measured to the distance measuring imaging means are configured to form a predetermined angle,
In the distance measuring device for measuring the distance of the object to be measured based on the light receiving center position detected by the light receiving center detecting means,
The light receiving center detecting unit compares the received light amount level at each pixel with a plurality of thresholds having different levels based on an imaging signal from the distance measuring imaging unit, and for each threshold, the threshold Extraction means for extracting a pixel group having the above received light amount level;
A center-of-gravity position detecting means for detecting each position of the center of gravity based the on the light receiving amount level of the pixel groups extracted by the threshold values in the extraction means,
A distance measuring device comprising: determining means for determining, as the light receiving center position, a center position obtained by averaging a plurality of the gravity center positions detected by the gravity center position detecting means. Wherein the plurality of threshold values, the distance A is detectable minimum light receiving quantity level or at the measuring pickup means, is set at a low level the range from the maximum received light quantity level on the imaging surface of the distance measuring image pickup means The distance measuring device according to claim 2, further comprising a threshold setting unit. Angle measuring light projecting means for projecting light on the object to be measured;
A converging lens that converges the reflected light projected from the angle measuring light projecting means and regularly reflected by the measured object;
An angle measuring imaging unit that receives light passing through the convergent lens on an imaging surface and outputs an imaging signal corresponding to the amount of light received for each image on the imaging surface;
A light receiving center detecting means for detecting a light receiving center position of the reflected light on the imaging surface based on an imaging signal output from the angle measuring imaging means;
In the angle measuring device for measuring the tilt angle of the object to be measured based on the light receiving center position detected by the light receiving center detecting means,
The light receiving center detecting means compares the received light amount level at each pixel with a plurality of thresholds having different levels based on the imaging signal from the angle measuring imaging means, and for each threshold value, the threshold value Extraction means for extracting a pixel group having the above received light amount level;
A center-of-gravity position detecting means for detecting each position of the center of gravity based the on the light receiving amount level of the pixel groups extracted by the threshold values in the extraction means,
An angle measuring apparatus comprising: a determining unit configured to determine, as the light receiving center position, a center position obtained by averaging a plurality of the barycentric positions detected by the barycentric position detecting unit. Wherein the plurality of threshold values, the there is detectable minimum light receiving quantity level or at an angle measuring image pickup means is set at a lower level below the range from the maximum received light quantity level on the imaging surface of the angle measuring image pickup means The angle measuring apparatus according to claim 4, further comprising a threshold setting unit. An optical measuring device that irradiates a measured object with light and measures the tilt angle and distance of the measured object based on the reflected light,
Angle measuring light projecting means for irradiating light as substantially parallel light toward the object to be measured;
A converging lens that converges the reflected light for angle measurement projected from the angle measurement light projecting means and specularly reflected by the measured object;
Imaging means for receiving light that has passed through the converging lens on the imaging surface and outputting an imaging signal corresponding to the amount of light received for each image on the imaging surface;
Distance measuring light projecting means arranged to irradiate the object to be measured with light as substantially parallel light from a direction inclined by a predetermined angle with respect to the light irradiation direction from the angle measuring light projecting means;
A converging lens that converges the distance measurement reflected light that is projected from the distance measurement light projecting means and diffusely or specularly reflected by the measured object;
Imaging means for receiving light that has passed through the converging lens on the imaging surface and outputting an imaging signal corresponding to the amount of light received for each image on the imaging surface;
A light receiving center detecting means for detecting a light receiving center position of each of the reflected light for angle measurement and the reflected light for distance measurement on the imaging surface based on an imaging signal output from the imaging means,
In the optical measuring device that measures the tilt angle and distance of the object to be measured based on the light receiving center position detected by the light receiving center detecting means,
The light receiving center detecting means sets the received light amount level at each pixel for each of the angle measurement reflected light and the distance measurement reflected light based on an imaging signal from the imaging means, and a plurality of thresholds having different levels from each other. And for each of those threshold values, an extraction means for extracting a pixel group having a light reception amount level equal to or higher than the threshold value;
A center-of-gravity position detecting means for detecting each position of the center of gravity based the on the light receiving amount level of the pixel groups extracted by the threshold values in the extraction means,
An optical measuring apparatus comprising: a determining unit that determines a center position obtained by averaging the plurality of barycentric positions detected by the barycentric position detecting unit as the light receiving center position. Threshold setting means is provided in which the plurality of threshold values are equal to or higher than a minimum received light amount level that can be detected by the imaging means and set to a level lower than the maximum received light amount level on the imaging surface of the imaging means. The optical measuring device according to claim 6, wherein

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