JP3444575B2 - Rangefinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates the surface of an object to be measured with laser light, receives the reflected light of the laser light from the surface of the object to be measured, and uses a triangulation method to measure the distance to the object to be measured. More specifically, the present invention relates to a range finder capable of determining the accuracy of distance data based on the quality of the surface state of an object to be measured.

[0002]

2. Description of the Related Art A rangefinder of this type, as shown in FIG.
The laser light emitted from the laser light generator 72 is applied to the lens 7
The surface of the object to be measured 71 is irradiated with the reflected light through the lens 74 and the CCD sensor 7 through the lens 74.
The distance can be calculated by receiving light at 5 and determining the peak pixel position.

Further, as shown in FIG. 8, the CCD sensor 7
In the case where there is only one, the reflected laser light is affected by the unevenness of the reflection on the surface of the object to be measured, and the distance detection accuracy is significantly reduced. Therefore, as shown in FIG.
Further, another CCD sensor 77 and a lens 76 are provided symmetrically to the lens 74 and the light receiving signals of the CCD sensors 75 and 77 are used to reduce the influence of uneven reflection on the surface of the object to be measured. .

[0004]

As described above, even with a rangefinder having two CCD sensors on the left and right, if the surface of the object to be measured has flaws or dust, the distance detection accuracy is remarkably high. There is a problem of decrease.

The present invention has been made in view of the above,
It is an object of the present invention to provide a range finder capable of determining the quality of the surface state of an object to be measured and improving the reliability of the accuracy of distance data.

[0006]

[0007]

[0008]

[0009]

[0010]

[0011]

In order to achieve the above object, the present invention irradiates a surface of a sheet-shaped object to be measured which is conveyed in a fixed direction with laser light and receives reflected light of the laser light from the surface of the object to be measured. A distance meter for measuring a distance to an object to be measured using a triangulation method, the laser light generating means for irradiating the surface of the object to be measured with laser light, and the laser light generating means for sandwiching the laser light generating means. First and second storage type light receiving means which are disposed on both sides of the light generating means and which receive the reflected light of the laser light on the surface of the object to be measured, and the light reception signals of the first and second storage type light receiving means. Based on, the determination means for determining the quality of the surface state of the object to be measured, and if the determination result of the determination means is defective, control is performed so as to discard the measured distance data, or the determination result is added to the distance data. Control means for controlling to output If the case where the judgment result of the serial determination section become, or if defective is defective continues for a predetermined time, the gist that it has a measurement position moving means for moving the measurement position substantially perpendicular to the conveying direction of the workpiece And

In such a structure, according to the present invention, when the surface condition of the object to be measured is defective or not.
If the case continues for a predetermined time , the measurement position is moved in a direction substantially perpendicular to the conveyance direction of the object to be measured, and the measurement is performed on another surface portion that avoids a portion having a poor surface condition.

[0014]

[0015]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a range finder according to an embodiment of the present invention. The range finder shown in the figure uses the laser light from the laser light generator 5 for the lens 7 and the slit 8.
CCD which irradiates the surface of the DUT 1 through the lens and reflects the reflected light through the lenses 9 and 11 to form a light receiving means.
Light is received by the sensors 13 and 15, and this light reception signal is used to calculate the distance.
The quality is supplied to the quality determination unit 17, the distance to the DUT 1 is measured using the triangulation method, the quality of the surface state of the DUT 1 is determined, and the output control unit 19 further determines the surface of the DUT 1. When the determination result of the state is good, the distance data is discarded or the distance data is output with the determination result added. In addition,
The DUT 1 is, for example, a steel plate, and is conveyed in a predetermined direction indicated by an arrow 3.

Further, the distance meters of the present embodiment configured as described above are arranged on both upper and lower sides with the object to be measured 1 interposed therebetween,
The distance between the front surface and the back surface of the DUT 1 is calculated by each distance meter, and the DUT 1 is calculated from these distance data.
Can be calculated.

In the present embodiment, distance measurement is performed at high speed and in a large amount at a pitch of 2 to 10 mm in the conveying direction of the object to be measured 1, and the average value thereof is calculated to calculate distance data or thickness data. That is, since the DUT 1 such as a steel plate rarely changes its surface shape and thickness rapidly,
By obtaining the average value, it is possible to obtain the measured value of the distance or the thickness.

Further, the distance calculation / good / bad judgment unit 17 judges the quality of the surface state of the DUT 1. When the judgment result is bad, the judgment result is added to the distance data and output. Alternatively, by discarding the distance data as necessary and using the average value before and after the discarded distance data, the abnormal distance data can be deleted and accurate distance data can be obtained.

In the present embodiment, the laser light generator 5
When irradiating the DUT 1 with laser light, the spot of the laser light is several mm, but the same data as a spot of several tens of mm like a rangefinder or a thickness meter using other radiation. The moving average of the pitch data of several mm can be obtained so that the data can also be collected. Also in this case, the abnormal data is deleted to improve the measurement accuracy of the distance data or the thickness data.

FIG. 2 is a diagram for explaining the quality judgment processing in the distance calculation / quality judgment section 17. The distance calculation / quality determination unit 17 determines whether the surface state of the DUT 1 is good or bad when the shape of the steel plate or the like as the DUT 1 is flat and has no inclination.
It is performed by comparing the signal peak values of 3 and 15.

That is, when the object to be measured 1 is a flat surface such as a steel plate, the amount of reflected laser light from the surface of the object to be measured 1 is almost the same as that of the CCD sensors 13 and 15, The peak values of the received light signals photoelectrically converted by the CCD sensors 13 and 15 also become substantially the same level. Therefore, CCD
If the respective peak values of the received light signals measured by the sensors 13 and 15 are PEAK13 and PEAK15 as shown in FIG. 2, the ratio of both peak values (PEAK13 / PEAK1
5) is almost 1.

However, as shown in FIGS. 3 and 4, when there is dust or scratches on the surface of the DUT 1, the difference between the two peak values is very different. Therefore, the light of both peak values (PEAK13 / PEAK15) is calculated, and it is judged whether or not this ratio is within a specific range including 1 as shown below. If the surface condition of 1 is good and it is out of the specific range, it is determined as bad.

A <PEAK13 / PEAK15 <b However, a <1, b> 1.

By the way, when the shape of the steel plate as the DUT 1 is inclined or the steel plate itself is inclined, the surface of the DUT 1 is free from dust and scratches by the above method. However, since there is a large difference between the peak values, the quality judgment based on the ratio of both peak values causes many false judgments and cannot be used.

Therefore, as shown in FIG. 5, two CCDs are used.
The laser light generator 5 responds to the detection signals of the sensors 13 and 15.
Performs the sum of products operation with the matching data of the same shape as the light intensity distribution of the laser beam from, and finds the peak position of the matching degree, which is this value, and obtains the second-order approximation data near the peak value from this matching degree data. The resolution of less than or equal to 1 pixel is obtained from this, and the quality of the surface state of the DUT 1 can be determined by using this processing.

That is, when there is no dust or scratches on the surface of the DUT 1, even if the steel plate as the DUT 1 is tilted, the positions of the light receiving pixels of the CCD sensors 13 and 15 are displaced, and the laser is not generated. A reflected photoelectric signal corresponding to the light intensity distribution of the laser light from the light generator 5 is obtained from the CCD sensor as indicated by 71 in FIG. 5B, but the surface of the DUT 1 has dust or scratches. In this case, a reflected light photoelectric signal which is considerably different from the light intensity distribution of the laser light is obtained from the CCD sensor as shown by 72 in FIG.

Therefore, in order to determine whether the surface of the DUT 1 is good or not, that is, whether the surface has flaws or dust, based on such a difference in waveform, the laser beam from the laser beam generator 5 is determined. 5 (a), which has the same shape as the light intensity distribution of
Create matching data as shown at 73 in (b),
The detection signal from the CCD sensor is subjected to a sum-of-products operation with this matching data to obtain a matching degree, and the value of this matching degree at the peak pixel position is compared with the matching degree at a pixel position distant from the peak pixel position by a predetermined position. Then, since the change in the light intensity of the reflected light of the laser light is found, the quality of the surface of the DUT 1 is determined based on the comparison result.

More specifically, as shown in FIG. 5B, the detection signal 71 from the CCD sensor in the normal case where there is no dust or scratch on the surface of the DUT 1 is summed with the matching data 73. The matching degree of the calculation result is shown in FIG.
As shown by a waveform 74 on the right side of (b), the peak value MAT1 of the matching degree 74 and the matching degree data MAT at a position separated by a predetermined distance X from the peak position.
When 2 is compared and the ratio of both is calculated, the ratio is large in the normal case where there is no dust or scratch on the surface of the DUT 1 as shown in FIG. As shown in a), when the surface of the DUT 1 has dust or scratches, the matching degree as a result of multiply-accumulate the detection signal 72 from the CCD sensor with the matching data 73 is shown in FIG.
As shown by the waveform 75 on the right side of (a), the peak value MAT1 of the matching degree 75 and the matching degree data MAT at a position separated by a predetermined distance X from the peak position.
When 2 is compared and the ratio between the two is calculated, if there is dust or scratches on the surface of the DUT 1 as shown in the figure, this ratio is relatively small.

Therefore, when the ratio of the matching degree is calculated, if the ratio is small, the surface of the object to be measured 1 has dust or scratches, and the surface condition of the object to be measured 1 is poor. If the ratio is large, it can be determined that the surface condition of the DUT 1 is good without dust and scratches. Since the matching degree data for determining the quality of the surface state of the DUT 1 changes considerably depending on the surface state of the DUT 1, the light intensity distribution of the laser light, the matching data, etc., the predetermined distance X and the matching degree. It is necessary to set the values of MAT1 and MAT2 so that they can be freely changed according to the situation.

As shown in FIG. 6, when there is a linear flaw or the like on the surface of the DUT 1 substantially parallel to the conveying direction 3 of the DUT 1, as shown in FIG. It is preferable to move the range finder in a direction substantially perpendicular to the transport direction to perform the measurement, but in order to perform such a move in a direction substantially perpendicular to the transport direction, the range finder is mounted on a trolley (not shown). Then
If the surface of the DUT 1 has scratches or dust, the trolley moves the rangefinder in a direction substantially perpendicular to the transport direction of the DUT 1 to avoid scratches, dust, etc. By performing the measurement at the position, it is possible to reduce the data of the defective portion due to flaws or dust on the surface of the DUT 1 as much as possible.

As described above, when the range finder is moved by the trolley, when measuring the DUT 1 having many scratches and dust on the surface, the measurement position must be frequently moved. Since it disappears and affects the life of the trolley, the life can be extended by arranging the range finder to move only when the surface condition continues to be defective for a certain number of times or more. If the movement distance is, for example, about 5 to 10 mm, the movement of the measurement position to this extent is within the allowable error.

[0034]

As described above, according to the present invention,
The surface of the sheet-like object to be measured, which is conveyed in a certain direction, is irradiated with laser light, the reflected light from the surface of the object to be measured is received, and the distance to the object to be measured is determined using the triangulation method. A distance meter for measurement, which is provided on both sides of the laser light generating means so as to sandwich the laser light generating means and a laser light generating means for irradiating the surface of the object to be measured with the laser light, First and second storage type light receiving means for receiving the reflected light from the surface of the object to be measured, and the quality of the surface state of the object to be measured is determined based on the light receiving signals of the first and second storage type light receiving means. The determining means; if the determination result of the determining means is defective, the control means controls so as to discard the measured distance data or outputs the distance data by adding the determination result, and the determining means. or if defective determination result is poor If the case made has continued for a predetermined period of time,
Since there is a measuring position moving means for moving the measuring position in a direction substantially perpendicular to the conveying direction of the measured object, the surface state of the measured object is defective or may be defective for a predetermined time.
If you continue, you can move the measurement position in a direction almost perpendicular to the conveying direction of the object to be measured, and you can perform measurement on another surface part avoiding the part with poor surface condition, and continue accurate measurement. can do. Furthermore, it is possible to reduce the movement operation that frequently occurs in the case of the object to be measured having a poor surface condition, and to suppress the decrease in the life of the movement mechanism.

[0035]

[0036]

[0037]

[0038]

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a distance meter according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining quality determination processing in a distance calculation / quality determination unit used in the rangefinder of FIG.

FIG. 3 is a diagram showing disturbance of reflected light when dust is present on the surface of the object to be measured.

FIG. 4 is a diagram showing the turbulence of reflected light when there is a flaw on the surface of the object to be measured.

5 is a diagram for explaining a process of determining the quality of the surface of the object to be measured based on the matching degree obtained by multiplying and summing the detection signals of the CCD sensor with the matching data in the rangefinder of FIG. Is.

FIG. 6 is an explanatory diagram when there is a linear flaw or the like on the surface of the object to be measured.

FIG. 7 is a diagram illustrating an operation of moving the rangefinder in a direction substantially perpendicular to the conveyance direction of the measured object when there are linear scratches on the surface of the measured object.

FIG. 8 is a diagram showing a configuration of a conventional rangefinder that irradiates the surface of the object to be measured with laser light and receives the reflected light.

9 is a diagram showing a configuration in the case where two light receiving means are provided in the range finder of FIG.

[Explanation of symbols]

1 DUT 5 Laser light generator 7,9,11 lens 13,15 CCD sensor 17 Distance calculation / quality judgment unit 19 Output control unit

Claims (2)

(57) [Claims] 1. A laser beam is applied to the surface of a sheet-shaped object to be measured which is conveyed in a fixed direction, the reflected light from the surface of the object to be measured is received, and the object is measured using a triangulation method. A distance meter for measuring a distance to an object to be measured, the laser light generating means for irradiating the surface of the object to be measured with laser light, and the laser light generating means arranged on both sides of the laser light generating means. , First and second storage-type light receiving means for receiving the reflected light of the laser light on the surface of the measurement object, and the surface state of the measurement object based on the light-receiving signals of the first and second storage-type light receiving means And a control means for controlling to discard the measured distance data or to output the distance data with the determination result added when the determination result of the determination means is defective. And the judgment result of the judging means is bad. That case, the distance meter and having a measurement position moving means for moving the measurement position substantially perpendicular to the conveying direction of the object to be measured. 2. A sheet-shaped object to be measured conveyed in a fixed direction is irradiated with laser light, the reflected light from the surface of the object to be measured is received, and the object is measured using a triangulation method. A distance meter for measuring a distance to an object to be measured, the laser light generating means for irradiating the surface of the object to be measured with laser light, and the laser light generating means arranged on both sides of the laser light generating means. , First and second storage-type light receiving means for receiving the reflected light of the laser light on the surface of the measurement object, and the surface state of the measurement object based on the light-receiving signals of the first and second storage-type light receiving means And a control means for controlling so as to discard the measured distance data or output the distance data by adding the determination result when the determination result of the determination means is defective. And the determination result of the determination means is defective. If the case that continues for a predetermined time, distance meter and having a measurement position moving means for moving the measurement position substantially perpendicular to the conveying direction of the object to be measured.