JP2851424B2 - 3D coordinate measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a three-dimensional coordinate measuring apparatus, and more particularly to a three-dimensional coordinate of an object whose physical position fluctuates along a light-section line, for example, a moving or vibrating object, at high speed and with high accuracy. The present invention relates to an improvement in an apparatus for measuring a three-dimensional coordinate of an object to be measured at a high speed and with high accuracy, the reflectance of which is extremely different due to a paint color of the object to be measured, and the like.

2. Description of the Related Art In the production process of mechanical parts and products, there are many demands for detecting the three-dimensional coordinates of a moving or vibrating object at high speed in order to measure and inspect its dimensions. In particular, when the object to be measured has a three-dimensional shape, the three-dimensional shape of the object to be measured is detected at a high speed in order to grasp the characteristics of the shape. There is a strong demand for efficient and accurate measurement of Conventional measuring means detects the shape of a moving object at high speed by projecting pulsed slit light on the surface of an object and calculating only the vicinity of the binarized slit light image. (JP-A-64-78109).

The conventional measuring means having the above configuration binarizes the center position of the light cutting line and then obtains it by thinning, so the detection resolution capability of the center position of the light cutting line is 0.5 pixel, and the shape detection accuracy is poor. In addition, a special camera controller or arithmetic control unit for partially reading out the TV camera signal is required, and the apparatus becomes expensive.

Further, as a method devised by the present inventors, in a light cutting method using a slit light source and a TV camera, the center of gravity of a light cutting line is detected for each horizontal scan of the TV camera, and three-dimensional coordinates are referred to with reference to a table. There is a device that detects in real time.

However, this device continuously projects slit light and captures the reflected light with a TV camera for 1/30 second, so if the object to be measured moves in 1/30 second, the image will be blurred, and three-dimensional coordinate detection is appropriate. Not.

In addition, when there is disturbance light having a wide wavelength range such as sunlight in a factory or the like, a sufficient sn ratio (hereinafter, referred to as s / n) cannot be obtained only by a pass filter that transmits only the wavelength of the slit light source. There are cases.

DISCLOSURE OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, to correctly detect the three-dimensional coordinates of an object moving at a high speed, and to detect an object having a greatly different reflectance that has not been found conventionally. The slit light projection intensity is set over a wide range so that a good reflection signal can be obtained, and the appropriate slit light projection intensity is automatically set for DUTs with different reflectivities. It is another object of the present invention to provide a three-dimensional coordinate measuring apparatus capable of performing a measurement and a correct three-dimensional coordinate measurement even under disturbance light such as sunlight.

A three-dimensional coordinate measuring apparatus according to a first aspect of the present invention includes a slit light source that projects slit light at a predetermined angle toward a surface of an object to be measured, and a light cutting line formed on the surface of the object to be measured by the slit light. A pulse signal generation circuit for supplying a pulse light emission command for pulse driving the slit light source in synchronization with a field signal of the TV camera, outputting a calculation period setting signal, and a horizontal scanning of the TV camera. An A / D conversion circuit for converting a video signal output from a TV camera into a digital video signal Vi in synchronization with a video signal, and a threshold setting circuit for setting a threshold for extracting a light cutting line from the video signal A light-section line extraction circuit that outputs a light-section line extraction signal only while the digital video signal Vi exceeds the threshold value, and a horizontal address that indicates the position of a horizontal pixel of a video element of the TV camera. A horizontal address generation circuit for generating Ki, and a cumulative addition circuit for cumulatively calculating the video signal Vi output through the A / D conversion circuit during a period in which the light cutting line extraction signal is output from the light cutting line extraction circuit. While the optical cutting line extraction signal is being output from the optical cutting line extracting circuit,
An accumulative multiplication circuit for accumulating a product Vi × Ki of a video signal Vi output through an A / D conversion circuit and a horizontal address Ki output from a horizontal address generation circuit, and an output ΣVi of the accumulative multiplication circuit × Ki is divided by the output ΣVi of the accumulative addition circuit, the calculated value Ks is output as a horizontal light cutting position, a horizontal light cutting position detection circuit, and the horizontal synchronization signal of the TV camera is counted, and the vertical light cutting position Ls is calculated. The vertical light cutting position detection circuit to be detected, and the correspondence between the horizontal light cutting position and the vertical light cutting position and the actual three-dimensional coordinate value of the surface of the DUT are determined in advance.
A lookup table that outputs a three-dimensional coordinate value of the surface of the object to be measured based on the horizontal light cutting position Ks and the vertical light cutting position Ls that are stored in a table by correcting the lens distortion of the TV camera and stored. And a storage circuit that can write the three-dimensional coordinate values output from the look-up table for a specific period in synchronization with the operation period setting signal.

The three-dimensional coordinate measuring apparatus according to the first aspect of the present invention having the above-described configuration is configured such that the height and the width set by the pulse signal generation circuit are directed toward the surface of the object whose position physically fluctuates (for example, moves or vibrates). A pulse slit light is projected. Since the light cut line image by the pulse slit light enters the TV camera only for a short period of the pulse, the slit light image obtained by the TV camera becomes a sharp image without blur. As a result, the position of the horizontal cutting line of the slit light image can be accurately detected, so that the three-dimensional coordinates can be correctly detected.

Furthermore, the average projection energy of the slit light by pulse slit light projection is 1: 50,000 or more (output of light source (corresponding to pulse height) Variable range 1: 50 × Pulse width variable range 1: 1,
(000 or more), it is possible to detect a good reflection signal even for an object to be measured having a very large difference in reflectivity, such as a painted body of an automobile. The three-dimensional coordinate value storage circuit stores the three-dimensional coordinate values output from the look-up table in a specific period during which the calculation period setting signal output from the pulse signal generation circuit is output (this period corresponds to the TV used). For example, CCD TV cameras are generally
Since an image captured in a certain field period is output as a video signal in a frame period immediately after the field, one frame period immediately after the field on which the pulsed slit light is projected is the above-described specific period. )
Since only writing is possible, the three-dimensional coordinate value of the DUT at the moment when the pulse is projected is correctly measured.

Then, the video signal is sequentially output from the TV camera in synchronization with the horizontal scanning, and each time the output of one horizontal scanning video signal from the TV camera is completed, the light cutting on the horizontal scanning line is immediately performed. The horizontal cutting position Ks and the vertical cutting position Ls of the line are detected. In particular, the present invention is a horizontal light cutting position
Uses the load averaging method to detect Ks and achieves accurate position detection.

Further, the present invention converts the three-dimensional coordinate values (X, Y, Z) of the light cutting line measurement point P present on this scanning line corresponding to each of the cutting positions Ks and Ls into almost the same values as the detection of Ks and Ls. It is characterized in that three-dimensional coordinate values of many points P0, P1,... Along the light cutting line are obtained simultaneously and in real time.

The present invention relates the correspondence between the horizontal light cutting position Ks and the vertical cutting position Ls and the actual three-dimensional coordinate values (X, Y, Z) of the surface of the device under test, by using the distortion of the lens used in the TV camera. The results are measured in advance, and the results are tabulated and stored in a look-up table. Then, based on the detected horizontal light cutting position Ks and vertical light cutting position Ls, three-dimensional coordinates of the surface of the object to be measured accurately and at high speed without special calculation and without being affected by lens distortion. Value (X, Y,
Z) is output.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are a block diagram and a timing chart, respectively, showing a first embodiment of the present invention, and FIGS. 3 and 4 are blocks each showing a second embodiment of the present invention. 5 and 6 (a) are a block diagram and a flowchart, respectively, showing a third embodiment of the present invention, and FIG. 6 (b) is a diagram of a TV camera with multiple reflection. FIGS. 7 (a) and 7 (b) are diagrams each showing a state of a video signal of a TV camera, and FIGS. 7 (a) and 7 (b) are diagrams showing a video signal intensity of a TV camera with respect to a slit light projection intensity. 9 (a), (b),
(C) is a diagram showing the change of vmax, W, ΔVi with respect to the slit light projection intensity, FIG. 10 is a diagram showing the incident energy of the slit light and sunlight to the TV camera, and FIG. 11 and FIG. FIG. 13 is a block diagram showing a fourth embodiment of the present invention, and FIG. 13 is a block diagram showing a fifth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION According to a second aspect of the present invention, the pulse signal generation circuit outputs an operation period setting signal only within one frame period immediately after a field period in which a pulse driving light emission command is output to a slit light source. The data is output to a storage circuit. CCD TV
Generally, a camera outputs an image captured during a certain field period as a video signal within one frame period immediately after the field, so that the coordinate value at the time of emitting the pulse slit light is correctly stored in the storage circuit.

By the calculation synchronized with the pulse slit light projection, even if the object is moving or vibrating at high speed, its three-dimensional coordinates can be detected correctly and in real time.

A third invention of the present invention is that the pulse signal generation circuit includes a start signal generation circuit that outputs a start signal for instructing a start of measurement in accordance with a position of the device under test in a measurement area, and immediately after the start signal is generated. A light emission command for pulse driving the slit light source is output in a field where the light appears.

In the three-dimensional coordinate measuring apparatus according to the third aspect of the present invention, the pulse signal generating circuit outputs a start signal for instructing the start of measurement in accordance with the position of the device under test in the measurement area by the start signal generating circuit. Along with the input of the field signal of the TV camera, by detecting the odd and even states of the field, while outputting a light emission command for pulse driving the slit light source during a field period that appears immediately after the start signal is input, An operation period setting signal is output to the storage circuit during one frame period immediately after the field where the pulse generation command is output. Since the CCD type TV camera outputs an image captured in a certain field period as a video signal in a frame period immediately after the field, the coordinate value at the time of pulse slit light emission is correctly stored in the storage circuit. . By the calculation synchronized with the pulse slit light projection, even if the object is moving or vibrating at high speed, its three-dimensional coordinates can be detected correctly and in real time.

Further, the average intensity (energy) of the projected slit light can be changed to an extremely large range by the pulse slit light projection. When a semiconductor laser is used as the slit light source, the stable variable range of the output is about 1:50, so the projection intensity (energy) of the slit light when continuously projecting the slit light is about 1:50. Automotive bodies are painted in white to black and glossy, so their light reflectivity can vary greatly and can be as high as 1: 1,000 or more. For this reason, continuous projection of slit light makes it impossible to obtain stable reflected light of slit light irrespective of the white to black body color. However, when this pulse projection is used, the average output of light can be controlled by the magnitude of the pulse width.

Because the CCD camera accumulates the light energy input within one field period, when the pulse width of the slit light is τ and the pulse height is h, just h × τ / τ _f
This is equivalent to the projection of continuous slit light having the intensity of.
Here, τ _f is one frame time.

Now, the range of h is about 1:50 of the variable range of the laser described above, and the range of τ / τ _f can be easily set to 1: 1,000 or more. Therefore, the variable range of the average intensity (energy) is eventually 1: 50 × 1,000 = 1: 50,000 or more. As a result, a good reflected light can be obtained even on a measured object having extremely different reflectances, such as glossy white and black, and correct three-dimensional coordinate measurement can be realized.

A fourth invention of the present invention includes a control circuit for controlling a projection intensity of slit light based on at least one of a light cutting line width detected at each horizontal scan and a maximum intensity of the light cutting line. It is characterized by.

Even if the intensity of the projected slit light is constant, at least one of the width and the maximum intensity increases as the reflectance of the measured object increases, even if the intensity of the projected slit light is constant. Therefore, by controlling the projection intensity of the slit light so that the width or the maximum intensity of the light cutting line detected every horizontal scanning becomes a preset value, it is possible to always obtain a constant reflected light. The projection intensity (energy) of the slit light can be controlled by changing at least one of the width and the height of the pulse light. Further, the intensity of the slit light may be determined so that the product of the light cutting line width and the maximum intensity for each horizontal scan has a preset value.

A fifth aspect of the present invention is characterized in that the fifth aspect of the present invention includes a control circuit for controlling the slit light projection intensity based on the output ΔVi of the accumulation circuit.

Since the output ΣVi of the accumulative addition circuit is an integral value of the light-section line intensity, it is more precise than the simple use of the light-section line width or the maximum value of the light-section line intensity for setting the slit light projection intensity for the following reasons. Automatic intensity setting.

As shown in FIGS. 7 (a) and 7 (b), the intensity v of the signal for one horizontal scan when observing the light cutting line by the TV camera is approximately the same as that when the semiconductor laser is used as the slit light source. The form of the Gaussian distribution of the following equation can be expressed as v = V ₀ · exp (−K ₀ −K _i ) / B).

Here, K ₀ is the horizontal coordinate of the TV camera when the intensity v becomes maximum (V ₀ ).

For example, when the driving current of the semiconductor laser as the slit light source is increased to increase the slit light projection intensity, V _{0 in the} above equation increases (B generally also increases). FIG. 8 shows this state. When the drive current is further increased, the CCD of the TV camera is generally saturated, and the signal intensity v is also saturated as shown in FIG. At this time, the relationship between the projection intensity (or drive current) and the maximum signal output vmax, the width W of the signal v crossing the threshold value, and the area ΔVi exceeding the threshold value are as shown in FIG.

As shown in FIG. 9 (a), vmax saturates at a high projection intensity, and is more susceptible to the superposition of noise. In addition, although W is unlikely to be saturated, it is quantized stepwise as shown in FIG. 9B according to the number of pixels of the TV camera. On the other hand, since ΔVi is an integral value, the saturation with respect to the projection intensity is small, and the change is smoother than the width W. For this reason, the automatic setting of the projection intensity can be precisely performed over a wide range by using the area ΔVi.

According to a sixth aspect of the invention, when projecting slit light with a pulse,
Only during the slit light projection period, the shutter of the TV camera is opened, and as described below, reflected light can be s / n well under disturbance light having a wide wavelength characteristic such as sunlight, as described below. Can be detected.

The TV camera converts the incident light into one frame time τ _F (τ _F =
33.3 msec) and output the result as a video signal. Now, pulse slit light (pulse width τ _P )
And _sl (joule / sec) and a _su (joule / sec), respectively,
When there is no shutter, the incident energy (Asl) of the pulse slit light and the incident energy (Asu) of the sunlight in one frame time are respectively calculated by time integration. Next, s / n becomes _{Asl / Asu = τ P a sl} / τ F a su.

Next, when the shutter of the TV camera is opened only during the pulse projection time τ _P , the incident energy of the pulse slit light to the TV camera (Asl ′) and the incident energy of sunlight (Asu ′) are respectively Next, s / n is expressed by _{Asl '/ Asu' = τ P} a sl / τ P a su = a sl / a su.

From this, for example, the pulse emission time τ _P is 33.3 μse
When c, at 1/1000 times the size of the solar energy a _su per pulse unit of the slit light time energy a _sl per unit time, s / n when the TV camera does not operate the shutter
Is 33.3 × 10 ⁻¹⁶ × a _sl /(33.3×10 ⁻³ × a _sl / 1000) = 1
Becomes On the other hand, when the shutter is operated, s / n is greatly improved to _asl / ( _asl / 1000) = 1000 under the same conditions. (Refer to FIG. 10.) According to a seventh aspect of the present invention, a window is set for an arbitrary range within a horizontal scanning period of a TV camera, and a coordinate calculation is performed only for a light cutting line existing in the window. It is characterized by the following. The purpose of this is to eliminate the influence of multiple reflection of slit light generated in a concave object or the like. When the shape of the object is known, it is often possible to predict in advance how multiple reflections will occur. In such a case, by setting a window in advance at the portion where the primary reflection signal is generated, a higher order (secondary, third order) can be obtained.
Next, three-dimensional coordinates can be accurately detected without being affected by reflection.

First Embodiment FIGS. 1 and 2 show a preferred first embodiment of a three-dimensional coordinate measuring apparatus according to the present invention. (Corresponding to the first and second inventions).

The apparatus of the first embodiment includes a slit light source 12 and a TV camera 14.

As shown in FIG. 1, a pulse slit light having a pulse width and a pulse height is synchronized with the field signal of the TV camera set by the pulse signal generation circuit 1 from the slit light source 12 toward the three-dimensional device under test. Is projected at a predetermined angle, and a light cutting line formed on the object to be measured is photographed using the TV camera 14.

When using a TV camera with a CCD area sensor,
A case where three-dimensional coordinates are calculated in real time by projecting pulse slit light will be described. In this case, in order to correctly obtain three-dimensional coordinates from the image of the TV camera obtained by pulse projection of the slit light, the pulse projection must start and end in the field immediately before one frame period in which the calculation is performed. .
This is because the CCD camera accumulates the energy of light input during a certain field period and outputs an image detected as a video signal in view of one frame period immediately after the field.

Hereinafter, a case where pulse emission is performed in an even-numbered field and coordinate calculation is performed in the next one frame (odd-numbered field + even-numbered field) will be described with reference to FIGS.

As shown in FIG. 2, assuming that a start signal is input from the start signal generation circuit 50 to the field detection circuit 51 in the pulse signal generation circuit 1 in the odd field of the TV camera, the odd field detection circuit 51 As shown in the figure, the end point (a ₁ ) of the odd field which is started after the start signal is input is detected, and this detection signal is supplied to the light emission signal generation circuit 52. The emission signal generating circuit 52 a predetermined pulse width τ from the pulse width setting circuit 53 in is given, the light emission signal having a pulse width τ in synchronization with the a ₁ point is generated. This light emission signal is supplied to the drive circuit 54. A predetermined pulse height h is given to the drive circuit 54 from the pulse height setting circuit 55, whereby the drive circuit 54 outputs a drive signal having a pulse width τ and a pulse height h to the slit light source. As a result, the pulse slit light is projected into the next even field (between a _{1 and} b ₁ ) in which the start signal is input. A stationary slit image is captured by the TV camera even with a vibrating object by the pulse slit light projection. On the other hand, the light emission signal is also input to the calculation period setting circuit 56 at the same time. The calculation period setting circuit 56 is supplied with the field start signal of an odd field detection circuit 51, thereby calculating the period setting circuit 56, the first frame period after leaving the light emitting signals (in this case b ₁ ~b ₍₂ ) An operation period setting signal is supplied to the storage circuit 48.

The coordinate calculation circuit composed of circuits 20 to 46 repeats the coordinate calculation in real time, and inputs the calculated coordinate values from the coordinate table to the recording circuit 48, so that the calculation period setting signal is stored. The coordinate calculation result during the period input to the circuit 48 becomes valid and is stored in the storage circuit 48. As a result, the coordinate values calculated during the first one frame period after the emission of the pulse slit light are correctly stored in the storage circuit 48.

By the calculation synchronized with the pulse slit light projection, even if the object is moving or vibrating at high speed, its three-dimensional coordinates can be detected correctly and in real time.

Further, since pulse light emission of the light source is used, it is possible to detect three-dimensional coordinates of a vibrating object without using a TV camera having a special function of a shutter function.

Further, by this pulse slit light projection, the average energy of the projected slit light can be changed to an extremely large range. When a semiconductor laser is used for the slit light source 12,
Since the stable variable range of this output is about 1:50, the projection intensity (energy) of the slit light when continuously projecting the slit light is about 1:50. Automotive bodies are painted in white to black and glossy, so their light reflectivity can vary greatly and can be as high as 1: 1,000 or more. For this reason, continuous projection of slit light makes it impossible to obtain stable reflected light of slit light irrespective of the white to black body color. However, when this pulse projection is used, the average output of light can be controlled by the magnitude of the pulse width.

This is because the CCD camera accumulates the light energy input within one frame period, and when the pulse width of the slit light is τ and the pulse height is h, the intensity of h × τ / τ _f is just continuous. This is equivalent to the projection of slit light.

Now, the range of h is about 1:50 of the variable range of the laser described above, and the range of τ / τ _f can be easily set to 1: 1,000 or more. ×
1,000 = 1: 50,000 or more. As a result, a good reflected light can be obtained even on a measured object having extremely different reflectances, such as glossy white and black, and correct three-dimensional coordinate measurement can be realized.

It should be noted that the present invention is not limited to the above embodiment, and the odd field detection circuit 51, light emission signal generation circuit 52, pulse width setting circuit in FIG.
Of course, part or all of the pulse height setting circuit 55, the pulse height setting circuit 55, and the operation period setting circuit 56 can be executed by software of a host computer provided outside.

In the above example, one frame (odd + even field) in which pulse emission is performed in an even field and coordinate calculation is continued.
However, the pulse emission may be performed in the odd field and the coordinate calculation may be performed in the subsequent one frame (even number + odd number field). Further, the field of pulse emission may not be determined in advance, and light may be emitted in a field immediately after a start signal is input, and calculation may be performed in one frame immediately after the start signal.

The horizontal address generating circuit 28 of the first embodiment is formed by using a counter, counts a clock signal output from the TV camera 14, and uses this count value Ki in the horizontal direction representing the horizontal position of the image sensor. The address is output to the accumulative multiplication circuit 32.

The accumulation circuit 30 is configured using a hardware multiplication accumulator. While the light-section-line extracting circuit 22 extracts and outputs a video signal exceeding the threshold determined by the threshold setting circuit 24 as a light-section line, the A / D conversion circuit 2
The output Vi of 0 is multiplied by the value “1”, and the accumulated value is Are sequentially output.

This accumulation operation is performed anew repeatedly each time a horizontal synchronization signal is output from the TV camera 14.

Therefore, the accumulation value is output from the accumulation circuit 30 every time the TV camera 14 outputs the horizontal scanning video signal.

The accumulative multiplication circuit 32 is configured using a hardware multiplication accumulator. And the light cutting line extraction circuit
A / D converter 2
The signal Vi output from 0 is multiplied by the horizontal address Ki output from the horizontal address generation circuit 28, and the accumulated value is multiplied. Are sequentially output.

This accumulation operation is repeatedly performed each time a horizontal synchronization signal is output from the TV camera 14.

Therefore, the accumulated multiplication circuit 32 outputs the calculated value every time the TV camera 14 outputs a horizontal scanning video signal.

Then, the two accumulated operation values ΣVi and ΣVi × Ki
Is input to a horizontal light cutting position detection circuit 38 'composed of a divider, where the latter is divided by the former,
The horizontal light cutting position Ks is determined.

The vertical light cutting position detection circuit 38 of the first embodiment is configured using a counter, and detects the number of the horizontal line currently being scanned by the TV camera 14, that is, the vertical light cutting position Ls.

In the first embodiment, the accumulative multiplying circuit 32 of the accumulative adding circuit 30 is constituted by hardware, and its operation delay time is several tens nsec. Therefore, in the first embodiment, even in the latest case, several tens nsec after the end of the horizontal scanning,
Vi, ΣVi × Ki, Ls can be detected.

Further, in the first embodiment, when a commercially available standard hardware divider is used as the horizontal light cutting position detection circuit 38 ', since the division time is several μsec, it is within 5 to 6 μsec after the end of the effective horizontal scanning. , The horizontal light cutting position Ks can be detected. Then, the horizontal light cutting position Ks and the vertical light cutting position Ls of each point P detected in this way are input to the lookup table 40. The lookup table 40 of the first embodiment stores the horizontal light cutting position Ks and the vertical light cutting position Ls, and the three-dimensional coordinate values (X, Y, Z) at each point on the surface of the actual three-dimensional device 10 to be measured. The correspondence is stored in a table in advance after correcting the lens distortion of the TV camera.

Then, each time the horizontal light cutting position Ks and the vertical light cutting position Ls are input, the corresponding three-dimensional coordinate values (X, Y, Z) are output to the storage circuit 48.

Therefore, according to the first embodiment, each time the horizontal and vertical light cutting positions Ks and Ls are detected, the measurement point P of the DUT 10 is performed without performing any special calculation or software processing.
, The three-dimensional coordinates (X, Y, Z) can be quickly output as accurate values corrected for lens distortion.

In the first embodiment, the lookup table 40
Is composed of an X coordinate table 42, a Y coordinate table 44, and a Z coordinate table 46. Each of the tables 42, 44, and 46 is formed using a ROM in which a correspondence table between the Ks and Ls and each of the three-dimensional coordinate values X, Y, and Z is stored in advance.

At the end of each effective horizontal scanning period, Ks,
When Ls is input to each of the tables 42, 44 and 46, the corresponding tables 42, 44 and 46 output the corresponding three-dimensional coordinates (X, Y, Z) after several hundred nanoseconds, and this is the pulse generation circuit. Is written to the storage circuit 48 only during the period when the calculation period setting signal is input.

In the first embodiment, the storage circuit 48 stores the TV camera 14
And the semiconductor memory having an address corresponding to each number of the horizontal line.

Then, at the address specified by the vertical light cutting position Ls (horizontal line number of the TV camera 14) output from the vertical light cutting position circuit 38, the three-dimensional coordinates (X, Y, Z) are sequentially stored. Specifying a memory address directly without using a computer in this way is called DMA (Direct Memory Addressing).

When data is directly stored in the semiconductor memory as described above, several hundred nanometers are input after the coordinate value is input to the memory.
Data storage ends in sec. That is, within one microsecond after the end of the effective horizontal scanning period, the three-dimensional coordinates (X,
The storage of (Y, Z) is completed.

In this way, according to the apparatus of the first embodiment, the three-dimensional coordinate value (X,
The detection and storage operation of (Y, Z) can be completed about 6 to 7 μsec after the effective horizontal scanning period of the TV camera 14, that is, within the retrace period.

As a result, according to the first embodiment, the three-dimensional coordinate value of one point can be detected in the horizontal scanning cycle (63.5 μsec) of the TV camera 14, and the three-dimensional coordinate value of each point along the light section line is calculated. It can be measured in real time.

Further, in the first embodiment, software processing by a microcomputer can be used for division for detecting the horizontal light cutting position Ks and writing of X, Y, and Z coordinate values to the semiconductor memory. .

In this case, since about 20 μsec is required for division and 20 μsec for writing to the memory, these processes cannot be performed within the retrace time as it is.

However, first, ΣVi and ΣVi × Ki are taken into a microcomputer, divided to obtain a horizontal light cutting position Ks, and then this Ks is stored in a separately provided latch circuit for one horizontal scanning period, and the latch output is output. The lookup table 40
To enter.

By doing so, the output of the lookup table 40 is held for one horizontal scanning period. Therefore, during this holding period, X, Y, Z output from the lookup table 40.
The coordinate values may be written to the semiconductor memory using a microcomputer only during the period when the operation period signal from the pulse generation circuit is input.

Such a method stores coordinate data of a measurement point existing on the horizontal line during the next horizontal line scanning period, and is one of pipeline processes. By performing such processing, even when a microcomputer is used to calculate the horizontal light cutting position Ks and write data to the semiconductor memory, there is a delay of one horizontal scan, but the three-dimensional coordinate value of one point is not changed. The detection memory is stored in the horizontal scanning time (6
(3.5 μsec) period, and the three-dimensional coordinate value of each point along the light-section line can be measured in real time.

Second Embodiment An apparatus according to a second embodiment of the present invention comprises a first device as shown in FIG.
Unlike the embodiment, the control circuit 5 includes a cumulative light-section line intensity storage circuit 6, an average value calculation circuit 7, a comparator 8, a cumulative light-section line intensity setting device 9, and a microcomputer 10. The microcomputer 10 is one of the pulse signal generation circuits.
Are connected to a pulse width setting circuit 53 and a pulse height setting circuit 55.

In the apparatus of the second embodiment having the above configuration, as shown in FIG. 4, the cumulative light section intensity output ΔVi for each horizontal scan is stored in the cumulative light section line intensity storage circuit 6, and the average intensity for one frame time is stored. Is calculated by the average value calculation circuit 7.
This value is stored in the comparator 8 by the cumulative light section line intensity setting unit 9.
The microcomputer 10 sets the pulse width and the pulse height of the slit light so that the upper limit and the lower limit set values are preset, and the values fall within the set values. That is, when the average intensity per frame time is out of the range of the upper limit and the lower limit, at least one of the pulse width τ and the pulse height h of the slit light is changed by a predetermined amount, and the average intensity is set to the set value. Try to stay within the range. For example, the pulse width can be minutely changed with one horizontal scanning time (63.5 μsec) as the basic change amount, and the pulse height can be minutely changed with 1/64 of the rated value as the basic change amount at 6 bits. Therefore, when the average intensity is larger than the upper limit, the pulse width or the pulse height is set to 63.5 μsec or 1/64 for each pulse emission.
The pulse width or the pulse height is fixed when the average intensity falls below the upper limit set value.
Similarly, when the average intensity is smaller than the lower limit set value, the pulse width or the pulse height is increased by each basic change amount. Here, for example, when the average intensity does not fall within the set value range within the variable range of only the pulse width, the pulse height may be sequentially changed next.

Furthermore, if the average intensity is significantly different from the upper and lower limit set values, changing the pulse width or height for each pulse emission as described above requires a long time for the average intensity to fall within the set value range. Become. In this case, the convergence of the average intensity within the set value range can be expedited by setting the amount obtained by multiplying each basic change amount by a coefficient proportional to the deviation amount between the average intensity and the set value as the change amount, The time required for the measurement can be reduced.

Since ΔVi is an integral value of the light-section line intensity, it is practically possible to perform a precise automatic intensity setting as compared to simply using the light-section line width and the maximum value of the light-section line intensity for the slit light projection intensity setting. Demonstrate meaningful effects.

Third Embodiment In a device according to a third embodiment of the present invention, a window circuit 15 includes a window setting circuit 11 and a gate circuit 13 as shown in FIG. A window is set for a necessary range for each horizontal scan of the TV camera. This range is a range in which the primary reflection component is imaged when the slit light is projected on the object to be measured, and can be determined in advance when the shape of the object to be measured is known. Only the light cutting line in this window is the gate circuit
It is extracted at 13 and output to the accumulation circuit 30 and the accumulation circuit 32. Therefore, the apparatus of the third embodiment is shown in FIG.
(B) As shown in the figure, the window is preset so as to remove the secondary, tertiary, and so on multiple reflections, so that the three-dimensional coordinates can be detected without being affected by the multiple reflections. Practically significant effects that cannot be achieved.

Fourth Embodiment A device according to a fourth embodiment of the present invention uses a TV camera 14 having an electronic shutter function as shown in FIGS. 11 and 12, and outputs a light emission signal generation signal for pulse emission to the TV camera. To the shutter control input circuit. The shutter can be opened only during the pulse light emission period to measure the three-dimensional coordinates of a vibrating or moving object with greatly different reflectance under s / n under disturbance light having components in a wide wavelength range such as sunlight. However, this embodiment is different from the above embodiments, and the other embodiment has the same operation and effect.

Fifth Embodiment In a fifth embodiment of the present invention, as shown in FIG. 13, a control circuit 105 includes a light-section line width storage circuit 101 and a maximum signal strength detection circuit.
102, maximum signal strength storage circuit 103, microcomputer
Consists of 100.

In the fifth embodiment having the above configuration, the microcomputer 100 is connected to the pulse width setting circuit 53 and the pulse height setting circuit 55 of the pulse signal generation circuit. The maximum intensity of the light cutting line signal for each horizontal scan is detected by the maximum signal intensity detection circuit 102, and the maximum intensity value of the light cutting line signal for the number of horizontal scanning lines is stored in the maximum signal intensity storage circuit 103. On the other hand, the output of the light cutting line extraction circuit 22 corresponds to the light cutting line width, and this value is stored in the light cutting line width storage circuit 101 for the number of horizontal scanning lines. The stored light-section line widths and maximum signal intensities for the number of horizontal scanning lines are input to the microcomputer 100, and are subjected to predetermined signal processing (for example, the light-section line width and the maximum signal strength in each one-frame period). The microcomputer calculates the average value, calculates the average value of the product of the light-section line width and the maximum signal intensity within one frame period, and makes the result equal to a predetermined set value.
100 sets the pulse width and pulse height of the slit light. The relationship between the light cutting line width and the slit light projection intensity (pulse height) of the maximum signal intensity is shown in FIG.
The result is as shown in FIG. Further, the product of the light-section line width and the maximum signal strength is approximately as shown in FIG. 9 (c), and is substantially the same as that of the above embodiment using the light-section line width, the maximum signal strength or their product. The slit light projection intensity can be controlled with the same accuracy and more easily.

By the way, when the object to be measured vibrates or moves at high speed, the slit light pulse width is kept narrow and the slit height is changed to control the slit light projection energy to obtain a sharp image without blur. Can be. For example, if the DUT oscillates with an amplitude of ± 1 mm and a frequency of 10 Hz, the measurement error must be measured with accuracy of ± 0.1 mm without blur, that is, as a stationary object. In the case of ± 0.02 mm, the pulse width needs to be about 500 μsec.

On the other hand, if the reflectance of the DUT changes over a wide range,
As mentioned above, since the variable range of the pulse height is relatively narrow,
By mainly changing the pulse width, the slit light projection energy can be controlled over a wide range, so that it is possible to measure an object to be measured having any reflectance. In this case, if the product of the pulse height and the pulse width is used, control over a wider range becomes possible.

INDUSTRIAL APPLICABILITY In the present invention, even when the object to be measured moves and vibrates at a high speed, and even when the reflectance of the object to be measured greatly changes, the three-dimensional coordinate value of the surface of the object to be measured can be calculated in real time. In addition, since it can be accurately detected, dimensional measurement and inspection can be performed in-line in the production process of mechanical parts and products. Therefore,
In addition to promoting the automation of the production process, the inspection accuracy is greatly improved as compared with the case of the operator.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-78108 (JP, A) JP-A-62-220803 (JP, A) JP-A-1-284982 (JP, A) JP-A-63-78 279110 (JP, A) JP-A-1-242906 (JP, A) JP-A-63-149507 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11 / 30

Claims (7)

(57) [Claims] 1. A slit light source for projecting slit light at a predetermined angle toward the surface of an object to be measured, a TV camera for photographing a light cutting line formed on the surface of the object to be measured by the slit light, A pulse light emission command for pulse driving the slit light source is supplied in synchronization with a field signal of the camera, and a pulse signal generation circuit for outputting an operation period setting signal is output from the TV camera in synchronization with horizontal scanning of the TV camera. An A / D conversion circuit for converting a video signal into a digital video signal Vi; a threshold setting circuit for setting a threshold for extracting a light cutting line from the video signal; A light-section line extraction circuit that outputs a light-section line extraction signal only while the value is exceeded, and a horizontal address that generates a horizontal address Ki that indicates the position of the horizontal pixel of the video element of the TV camera The generation circuit and the video signal Vi output through the A / D conversion circuit during the period when the light-section line extraction signal is output from the light-section line extraction circuit.
And a video signal Vi output through the A / D conversion circuit while the optical cut line extraction signal is being output from the optical cut line extraction circuit.
And a cumulative multiplication circuit for accumulating a product Vi × Ki of the horizontal address Ki output from the horizontal address generation circuit; and A horizontal light cutting position detection circuit that outputs the calculated value Ks as a horizontal light cutting position, and counts the horizontal synchronization signal of the TV camera to determine the vertical light cutting position.
The vertical light cutting position detection circuit that detects Ls, and the correspondence between the horizontal light cutting position and vertical light cutting position and the actual three-dimensional coordinate value of the surface of the DUT are tabulated by correcting the lens distortion of the TV camera. A lookup table that outputs three-dimensional coordinate values of the surface of the device under test based on the detected horizontal light cutting position Ks and the detected vertical light cutting position Ls, and a three-dimensional coordinate value output from the lookup table. ,
A storage circuit that enables writing only for a specific period in synchronization with the operation period setting signal, wherein the three-dimensional coordinates of the surface of the object to be measured are measured in real time along the light-section line. Coordinate measuring device. 2. The apparatus according to claim 1, wherein said pulse signal generation circuit outputs an operation period setting signal only in a frame period immediately after a field period in which a pulse driving light emission command is output to a slit light source. 3D coordinate measuring device. 3. The pulse signal generating circuit includes a start signal generating circuit for outputting a start signal for instructing a start of measurement in accordance with a position of an object to be measured in a measurement area, and appears immediately after the start signal is generated. The three-dimensional coordinate measuring apparatus according to claim 1, wherein a light emission command for pulse driving the slit light source is output to a field. 4. A control circuit for controlling a projection intensity of slit light based on at least one of a light cutting line width and a maximum intensity of the light cutting line detected for each horizontal scan. The three-dimensional coordinate measuring device according to claim 1. 5. The three-dimensional coordinate measuring apparatus according to claim 1, further comprising a control circuit for controlling a slit light projection intensity based on an output ΣVi of said accumulation circuit. 6. The three-dimensional coordinate measurement according to claim 1, wherein the TV camera has an electronic shutter function that is opened only during a period when a pulse generation command is generated from the pulse generation circuit. apparatus. 7. The three-dimensional coordinate measuring apparatus according to claim 1, further comprising a window circuit for setting a window for each horizontal scan of the TV camera and extracting only a light cutting line within the window.