JPH0526620A - Defective action detecting method for laser sensor - Google Patents

Abstract

PURPOSE:To provide the method for checking the defective action 1 the detecting element of a noncontact type laser sensor. CONSTITUTION:An auxiliary detecting member is fitted at the preset position on the table of a digitizer. The laser beam of a laser sensor 8 is reflected by a reflecting mirror 12 and focused and projected on picture elements of a CCD detecting element 9 with a condensing lens 8a to form a focal point. The angle thetai of the reflecting mirror 12 against each group of picture elements and the Z-axis distance Zi from the reflecting mirror 12 of a sensor are read from a memory circuit, the output distribution value of each group picture elements when the light is received is compared with the normal output distribution of each group of picture elements, the position of defective picture elements is stored, and the function of the CCD is confirmed in advance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type sensor, and more particularly to a method for detecting a malfunction of an element of a laser light type sensor, that is, a failure of a detecting element.

[0002]

2. Description of the Related Art A defect of a pixel of a detection element of a laser sensor used in a non-contact digitizer has not been checked before operation.

[0003]

For this reason, if the sensitivity of the pixels of the CCD, such as defectiveness of the CCD, or partial destruction occurs in the detection element, the detection accuracy becomes poor, and the digitizer does not function properly.
In some cases, there may be a collision between the sensor and this machine. The present invention has been made in view of the above problems in the related art, and an object of the present invention is to detect a malfunction of a detection element in advance to determine whether or not it can be used and detect a malfunction of the detection element as a reliable sensor. It is intended to provide a method.

[0004]

In order to achieve the above object, the present invention provides a detection element for a laser beam reflected by a mirror provided at a laser beam irradiation position of the sensor and capable of changing a reflection angle by a turning means. Is controlled so as to sequentially irradiate the detection areas of the divided areas, and it is inspected whether or not the detection output of each position of the detection element is normal.

[0005]

Before the digitizer starts measuring, a detection assisting member composed of a turning means and a reflecting mirror is mounted on a table, a laser sensor is positioned above the reflecting mirror, and the turning means sequentially turns the reflecting mirror at a predetermined angle. The Z-axis position is controlled so that the reflected light is focused on the pixels obtained by dividing the detection area, and the output value of each pixel of the pixel group at this time is lower than the set value. ..

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below with reference to FIGS. A model 2 is mounted on a guide surface on the bed 1, a table 3 that can be controlled to move in the X-axis direction is placed, and top beams 5 are mounted on columns 4 established on both sides of the bed 1 to form a gate-shaped column. Has been formed. A spindle head 6 whose movement is controllable in the Y-axis direction is suspended on the top beam 5, and a quill 7 is supported so that the movement of the Z-axis can be controlled. A non-contact type laser sensor 8 is attached to the quill 7. The laser light of the laser sensor 8 is convergent light that focuses on the measurement point by the projection lens, and the reflected light from the model is converged on the pixel of the detection element, for example, the CCD detection element 9 by the light receiving lens 8a and focused. Be done. An output of a predetermined level can be obtained from the pixels received by the CCD detection element 9. Then, this output is sent to and stored in the control device 10.

The detection assisting member for detecting the quality of the operation of the detection element is a reflection mirror 12 whose output shaft of the pulse motor 11 controlled by the control device 10 has a surface including the shaft center thereof as a reflection surface.
Is attached, and is formed into a unit that can be attached and removed freely. The mounting position of the table 3 is defined so that the turning axis of the reflecting mirror 12 is exactly at a predetermined position on the table 3. The CCD detection element is, for example, 1
It is assumed that 5000 pixels each having 7 μm of pixels are arranged in a straight line. The pixel arrangement direction of the CCD detection element 9 is orthogonal to the output shaft of the pulse motor 11 of the detection assisting member.

In order to irradiate each pixel of the CCD detection element 9 with a predetermined amount of light or more, the reflected light passes through the center of the lens 8a and the reflection mirror 12 with respect to the laser light in the vertical direction.
The reflection mirror 1 when the upper focal point is away from the center of rotation of the reflection mirror by a predetermined distance and the reflected light traces on the pixel.
The angle θi of 2 is regulated by the pulse motor 11. Also C
The distance Zi between the sensor 8 and the reflection mirror 12 is adjusted by controlling the quill 7 along the Z-axis corresponding to the angle θi so that the focus is always focused on the pixel of the CD detection element 9.

The NC control device 10 includes the following. In FIG. 4 showing the control diagram, reference numeral 21 denotes a pixel group in which several CCD detection elements 9 are set, or an angle of the reflection mirror 12 when reflected light is incident on each pixel through the center of the condenser lens 8a. MDI for inputting the calculated value of θi and the Z-axis position Zi of the sensor 8 when focusing on the pixel group center of the CCD detection element, 22 is a memory circuit for storing the input calculated value, and 23 is a command value Comparison calculation circuit with the current value,
24 is a Zi (X, Y) function generation circuit,

Reference numeral 25 is a Z-axis drive circuit, 26 is a servo motor for moving the Z-axis (quill 7) up and down, and 27 is a Z-axis encoder. 28 is a pulse generator, 29 is a rotation indexing circuit for the reflection mirror, and 30 is the number of times 1 for each rotation indexing of the reflection mirror until the division number n is set by setting several pixels of the CCD detection element 9 as a set. A reflection mirror index frequency addition / comparison circuit for adding and comparing with n, and 31 is the number of times the reflection mirror 12 is indexed n.
When 1 is reached, 1 is added and the set number of times, for example, 3, that is, the number of repetitions 3 is compared.

Reference numeral 32 is a reflection mirror indexing power addition and comparison circuit 3
A program for sequentially instructing θi and Zi each time they are added with 0, issuing a command to reverse the reflection mirror 12 to the initial position when it becomes a multiple of n, and completing the check when the number of repetitions reaches 3 (3n) It is an analysis unit. Reference numeral 35 is an X-axis drive circuit, 36 is an X-axis drive servo motor, 37 is a Y-axis drive circuit, and 38 is a Y-axis drive servo motor.

Reference numeral 40 denotes a storage circuit for sequentially storing the output distribution of the pixel group of the CCD detection element 9 of the sensor 8 for each set, and 41 calculates the average distribution value of the set number when the number of repetition reaches the set value. An average value calculation circuit, 42 is a pixel distribution comparison / determination circuit that compares the set distribution value with the average distribution value and determines whether or not the operation state is good for each pixel, and 43 stores the address of a defective pixel if the determination result indicates that there is a defective pixel. Defective pixel address storage circuit.

In such a structure, assuming that the reflected laser light has a width several times larger than the pixel pitch, the pixels arranged in one line have one point at the center as the maximum output, and the output is gradually output on both sides thereof. Draw the output curve of the falling normal distribution. Therefore, assuming that a stable value of the output level, for example, 1/2 or more of the normal output is output, the angle θi of the reflection mirror 12 is calculated so that the reflected light moves at a pitch of 35 μ and the Z-axis distance Zi is calculated. Is calculated in advance M
It is assumed that it is input to the DI 21 and stored in the storage circuit 22. It is assumed that the program analysis unit 32 has a built-in program for changing θi and Zi by one pitch and returning θi and Zi to initial values in order to repeat one cycle.

In the control flow chart shown in FIG. 5, step S
In 1, the program analysis unit 32 commands the check position of the quill 7. In step S2, the X-axis and Y-axis values of the auxiliary member are read out from the memory circuit 22, and the motors 36 and 38 are rotated by the X-axis drive circuit 35 and the Y-axis drive circuit 37 by the function generator 24 to detect the quill 7. Position directly above. In step S3, the sensor power supply is turned on. In step S4, the program analysis unit 32 commands Z ₁ for the initial position of the pixel edge of the CCD detection element 9. Storage circuit 2 in step S5
Zi is read from 2, and the quill 7 is positioned by driving the servo motor 26 by the Z-axis drive circuit 25 from the function generator 24.

The command value is compared with the comparison operation circuit 23 by the feedback of the output of the encoder 27, and accurate positioning is performed. In step S6, the program analysis unit 32 commands the angle θ _{1 of the} reflection mirror with respect to the first set of pixels at the end of the CCD detection element 9. Step S
Corresponding to the number of pulses to drive the reflecting mirror turning indexing circuit 29 with a pulse of the pulse generator 28 reads the theta ₁ from the memory circuit 22 drives the pulse motor 11 indexes the angle of the reflecting mirror at 7.

In step S8, the output distribution of the pixel group of the first set of the CCD detection element 9 upon which the reflected light of the laser beam of the sensor 8 is incident is stored in the storage device 40. In step S9, the reflection mirror index frequency addition / comparison circuit 30 adds 1 and it is determined in step S10 whether i + 1 is smaller than n. In this case, n is 5000/5 = 1000. If YES, the program analysis unit 32 commands the Z-axis Zi + 1 in step S11. Step S1
In step 2, Zi + 1 is read from the memory circuit 22, the function generator 24 rotates the motor 26 in the Z-axis drive circuit 25, and the current value of the encoder 27 and the command value are matched.

In step S13, the program analysis unit 32 commands the angle θi + 1 of the reflection mirror 12. In step S14, θi + 1 is read from the memory circuit 22 and the reflection mirror rotation indexing circuit 29 is read by the pulse generator 28.
The pulse motor 11 is rotated to index the reflection mirror 12. Then, the process proceeds to step S8. If NO in step S10, i + 1 is n in step S15.
To determine if. If YES, the process proceeds to step S4, and the reflection mirror 1
The angle of 2 and the Z axis position of the quill are returned to the initial θi and Zi, and then the second step is continued.

If NO in step S15, it is determined in step S16 whether i + 1 is smaller than 2n. If YES, steps S11, S12, S1 are performed again.
3 ... is repeated. If NO in step S16, it is determined in step S17 whether i + 1 is equal to 2n. If YES, the process proceeds to step S4, and the program analysis unit 32 similarly continues the third step. If NO in step S17, step S1
3n = i + 1 is compared in 8, and if NO, step S
The process proceeds to 11 and continues until YES. If YES, the average distribution value of the three detection values of each set of pixels stored in the storage circuit 40 is sequentially calculated by the average value calculation circuit 41 in step S19.

In step S19, the detected values of each set stored in the storage circuit 40 three times are sequentially calculated as the average value calculation circuit 41.
The average distribution value is calculated at. The distribution value set in step S20 and the pixel output distribution comparison / determination circuit 42 make a determination,
If there is a defective pixel, it is stored in the defective pixel address storage circuit 43 in step S21. In step S22, it is determined whether or not the comparison of all the sets of pixel divisions is completed. If NO, the process proceeds to step S19 to sequentially perform the comparison, and step S22.
If YES, the process ends. Then, the defective pixel is excluded and used, but if it is fatal, it is replaced.

In this embodiment, the pixels of the CCD detecting elements are arranged in one row, but in the case of arranging the pixels in a plurality of rows, the sensor is controlled to position X and Y after the check of one row is completed. It is possible to perform the same operation by shifting the lines. In the element of the embodiment, since there are 5000 sets of 7 μm, θi and Zi values are stored in the storage circuit of the control device 9 so that the light spots move in a pitch of 7 μm in the range of 35 mm and the Zi values are set. You may make it check pixel by pixel.

[0021]

Since the present invention is constructed as described above, the present invention has the following effects. Since the function of the sensor 8 can be confirmed and the degree of deterioration can be grasped before starting the actual operation, it is possible to minimize damage such as loss of time for data re-acquisition due to a defect and deterioration of reliability due to inaccurate execution. You can hold it down. Furthermore, by detecting a sensor failure in advance, it is possible to prevent damage to the sensor and machine.

[Brief description of drawings]

FIG. 1 is a diagram showing a laser sensor and a detection assisting member.

FIG. 2 is a diagram showing an optical path of a laser beam at the time of detection.

FIG. 3 is a diagram showing a digitizer.

FIG. 4 is a control block diagram.

FIG. 5 is a control flowchart.

FIG. 6 is a flow chart of control.

[Explanation of symbols]

 7 Quill 8 Sensor 9 CCD detection element 11 Pulse motor 12 Reflection mirror

Claims (1)

Claim: What is claimed is: 1. A laser beam reflected by a mirror provided at a laser beam irradiation position of a laser type sensor and capable of changing a reflection angle by a swivel means, at a position where a detection area of a detection element of the sensor is divided. A method for detecting malfunction of a laser sensor, comprising controlling the turning means so as to sequentially irradiate and inspecting whether or not the detection output at each position of the detection element is normal.