JPH0721404B2 - Width and step detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a two-dimensional (x) system that combines a light source of a laser or a light emitting diode (LED) and a two-dimensional optical position detector, which uses a light cutting method. , z) The present invention relates to a method for detecting a width between work and a step difference using a position detection sensor.

[Conventional technology]

The appearance of a two-dimensional position detecting sensor equipped with a two-dimensional optical position detector by the light cutting method is as shown in FIG. 8th
In the figure, (1) is a light source by a laser or a light emitting diode, and the light from this light source (1) passes through a condenser lens (2), a mirror (3), a scanning mirror (4) and a mirror (5). After entering the object (6) and receiving a part of the reflected light (7) (scattered light) from this incident part by the light receiving lens (9) provided in the lens holder (8), the two-dimensional light position Focus on the detector (10). The optical position detector (10) is attached to the sensor head (13) via a mounting bracket (11). The above components are housed in the sensor head (13).

FIG. 9 is a block diagram showing the hardware that processes the signal from the two-dimensional optical position detector (10). The data normalized by the divider (27) is the A / D converter (30).
After that, it is taken into the CPU bus as processing data. In the figure, (21) is a preamplifier that amplifies the signal from the optical position detector (10), (22) is a bandpass filter (BPF) composed of operational amplifiers, and (23) is a bandpass filter (22). Half-wave rectifier circuit, which rectifies the output signal, (24)
Is a low-pass filter (LP) that converts the output signal of the half-wave rectifier circuit (23) into a continuous analog signal of the current signal. These (21) to (24) are 4ch output X of the optical position detector (10). , X
It is provided for each of a, Y, and Ya. In the measurement, X,
Z is used, but here, X and Y are used for calculation. (twenty five),
(26) is a subtracter and an adder each composed of an operational amplifier, etc., (27) is a divider that receives outputs from the subtractor (25) and the adder (26), and (28) is division Bowl (27)
A sample and hold circuit (S / S) for sampling the analog signal of the calculation result of and holding it for the time required for signal conversion.
H) and (29) are analog switches (ASW) composed of field-effect transistors, and (30) is an A / D converter that outputs the converted digital signal as processed data to the CPU bus. There is.

A sensor using a two-dimensional optical position detector based on the light section method can detect the distance (Z) from the reference position and the width direction displacement (X). Based on this detection result, the signal processed and normalized as shown in FIG. 9 (that is, the A / D converter (3
The value of the step and the width can be calculated from the output signal from (0)), which is conventionally obtained from the intersection of the tangents of the data.
This conventional method is shown in FIGS. 10 and 11 (a) to (f).
It will be described based on. FIG. 10 is a flow chart of an algorithm showing signal processing for detecting width and step, and FIGS. 11 (a) to (f) are output signals X and Y in the block diagram of FIG.
Signal waveforms (described later) are shown for each axis, and the width and step are calculated in the same process by the segment method based on the differential data array. That is, as shown in the figure, when the waveform relating to the surface of the work as an object has a shape (image waveform) (41), first, the light quantity at the sampling point (42) is checked (step 10
1) A data array is created from a set of point sequences (step 102) (see FIG. 11 (a)). Next, based on the differential data array, the data group is segmented (43) (step 103) (FIG. 11 (b)), and the representative segment (44) in the horizontal and vertical directions is determined (step). 104)
(Fig. 11 (c)). Then, based on the data belonging to the representative segment (44), the regression line (4
5) is calculated (step 105) (FIG. 11 (d)). Finally, the intersection (46) of two horizontal and vertical straight lines is calculated (step 106) (Fig. 11 (e)), and each coordinate (the output signal is x, z in the measurement, but here it is calculated. Output signal x, y
I am trying. Note that x = (X−Xa) / (X + Xa), y = (Y
−Ya) / (Y + Ya)), the difference between the coordinate values of the intersection (46) is calculated as the width w of the object in the x direction and the step H of the object in the y direction (step 107) (FIG. 11 (f )).

[Problems to be Solved by the Invention]

The conventional method of irradiating an object with light and receiving the reflected light from the object to detect the width and step is configured as described above, and output signals x, y (Fig. 9) Because of the nature of the divider (27) in Fig. 9, the detection of width is a measurement of the same width, as shown in Fig. 12 for showing the signal waveforms taken along the axis and for defining "width". However, the waveforms were shaped like (41a), (41b), and (41c), so that the width dimensions varied as Wa, Wb, and Wc. Step H
As for Fig. 13, there were variations such as Ha, Hb, and Hc.

Further, the above-mentioned conventional method, if it is only necessary to detect the indentation, when trying to detect something like a through hole without a bottom, there is also a problem that it is difficult to determine how reliable the data is and it is not possible to accurately detect. there were.

The present invention has been made to solve the above problems, and an object thereof is to obtain a width and step detection method capable of accurately and stably detecting the width and step.

[Means for Solving the Problems]

The width and step detection method according to the present invention is a method for detecting a width and step by irradiating an object with light and receiving reflected light from the object to detect the width and step, wherein the irradiation The first step of obtaining the position of the side wall of the step portion from the change in the amount of light received from the sampling point group of the collected light, and then obtaining the width between the side wall surfaces from this position, and the variation of the light amount at the sampling point is small. The second step is to obtain straight lines in the stable region portion, then obtain respective intersections of the respective straight lines and the positions of the both side wall surfaces, and then obtain a step between the intersections.

[Action]

In the present invention, since the change in the amount of light received from the work is detected, the position of the side wall surface of the step portion can be detected. Therefore, the vertical line at this position can be obtained without variation and the width can be accurately obtained. You can Further, the step can be accurately obtained by obtaining the intersection of the vertical line and the regression line having no variation in the stable region of the sampling point.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the width and the level difference (for example, the width and the level difference between the works) are detected. For the width detection, the light amount is checked as a pre-normalization step rather than the image data (normalized data), and the position is set at the bottom. It is detected by counting the number of data to be processed, and the step is detected from the image data. This is to obtain a straight line by the method of least squares as in the prior art, but the step is obtained from the intersection of the vertical line indicating the width and the straight line.

FIG. 1 is a flow chart of the width detection algorithm, second
11A and 11B are diagrams showing signal waveforms similar to FIG. 11, and when the waveform formed by the sampling points (42) of the irradiated light has a shape (61), first the sampling points are shown. Regarding the light quantity of (42), after checking the number that the signal is above a certain level (step 201), the number of sampling points (42) which are the step portion, that is, the dark (DARK) portion (62) is counted (step). 202). Next, find the x-coordinates (eg, left end is X _L , right end is X _R ) of both ends of the dark (DARK) portion (62) (for example, the gap portion) where the light quantity (signal level) of the sampling point (42) is dark. (step 203) (FIG. 2 (a)), then obtains the width of the gap _{(w = X L -X R)} ( step 204) (FIG. 2 (b)). However, the steps 201 to 204 are the sampling points (4
2) The side wall surface of the stepped portion (6
3), the position X _L, obtains the X _R, then the position X _L of (64), X _R
The first step (205) for obtaining the width w between the side wall surfaces (63) and (64) is constituted.

FIG. 3 is a flowchart of an algorithm for detecting a step, and FIGS. 4 (a) to 4 (e) are signal waveforms similar to FIGS. 11 (a) to 11 (f), which are formed by sampling points (42). If the waveform to be generated is shape (61), first sampling point (42)
, The left regression line (72) of the left stable region (stable and small variation) (71) is calculated (step 301) (Fig. 4 (a)), and then the dark light ( 62) Find the x-coordinates (eg, left end is X _L , right end is X _R ) of both ends of (for example, the gap) (step 30)
2) (Fig. 4 (b)). Then the right regression line (7) of the right stable region part (73) where the sampling point (42) can be trusted.
4) is calculated (step 303) (FIG. 4 (c)), and then x
Calculate the Y coordinate Y _L of the intersection (76) of the vertical straight line (75) with the coordinate X _L and the left regression line (72), and the vertical straight line (77) with the x coordinate X _R and the right regression The Y coordinate Y _R of the intersection (78) with the straight line (74) is calculated (step 304) (FIG. 4 (d)). Then obtains the level difference _{H (H = Y R -Y L} ) ( step 305)
(Fig. 4 (e)). Then, these steps 301-305
, Each stable region part (71) of the sampling point (42),
The straight lines (72) and (74) are obtained in (73), and then the straight lines (72) and (74) and the vertical lines (75 at the positions X _L and X _R of the side wall surfaces (63) and (64) are determined. ), (77) intersection (76), (7
The second step (306) for obtaining the step 8 and obtaining the step H between the intersections (76), (78) is constituted.

FIG. 5 shows a signal waveform in which the output signals x and y are taken on each axis and defines the “width”. By detecting the end positions X _L and X _R of the dark portion (62), the width ( w = X _L −X _R ) can be detected. The value of the width w is not affected by the unstable signal waveform shape (61a), (61b) or (61c).

In FIG. FIG. 6 is to define a "step", both end positions X _L of the dark portion (62), X _R and the vertical bar (75), (77) is obtained, more stable region portion (71), (73) From regression line (72), (74)
Is calculated on the left and right, and the Y coordinates of the intersections (76) and (78) of the two straight lines
The step H is obtained from Y _L and Y _R.

By the way, in the above embodiment, as shown in FIG.
The case where the positions of both ends of the (K) part (62) are detected is explained, and the definition of the dark part (62) is the sample point group with the lowest signal level (the part of the valley seen in the waveform). On the other hand, the same applies when a threshold value C is provided for the signal level and the end sampling point when a certain level or higher (or lower) is detected as shown in FIG.

In the above embodiment, the case where the width of the concave portion is obtained has been described, but the present invention can be applied to the case where the width of the convex portion is obtained. Further, the step may be zero.

〔The invention's effect〕

As described above, according to the present invention, it is possible to stably and accurately detect the width and the step, and the respective positions.

[Brief description of drawings]

FIG. 1 is a flow chart for width detection showing an embodiment of the present invention, FIGS. 2 (a) and 2 (b) correspond to FIG. 1, and are explanatory diagrams showing signal waveforms, and FIG. 3 is for step detection. 4 (a) to 4 (e) correspond to FIG. 3 and are explanatory diagrams showing signal waveforms, FIGS. 5 and 6 are explanatory diagrams for defining width and step, and FIG. 7 is FIG. 8 is an explanatory view showing another embodiment of the present invention, FIG. 8 is an external view of a two-dimensional position detecting sensor, and FIG.
FIG. 11 is a block diagram, FIG. 10 is a flowchart showing a conventional width and step detecting method, and FIGS.
Corresponding to FIG. 10, an explanatory view showing signal waveforms, and FIGS. 12 and 13 are explanatory views for defining a width and a step in the related art, respectively. (6) …… Target object, (7) …… Reflected light, (42) …… Sampling point, (63), (64) …… Step side wall surface, (71), (73) …… Stable area part , (72), (74) …… straight line, (76), (78) …… intersection, (205) …… first process, (306) …… second process, w …… width, H …… step , X _L , X _R …… The position of the side wall of the step. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A method of detecting a width and a step by irradiating an object with light and receiving reflected light from the object to detect a width and a step, and a sampling point group of the irradiated light. The first step of obtaining the position of the side wall of the step portion from the change in the amount of light received from the side, and then the width between the side wall surfaces from this position, and the straight line in each stable region portion where the variation in the light amount at the sampling point is small And a second step of obtaining each intersection between each straight line and the positions of the both side wall surfaces, and then obtaining a step between the intersections.