JPH023121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for extracting a photosection line from a photosection image optically detected by a photosection method.

FIG. 1 shows an example of the optical system configuration for the light sectioning method. In the figure, numeral 1 is an observation target whose shape is to be measured, and as an example, a case where a soldered surface 1a on a printed board is inspected is shown. 2 is a slit projector for projecting a slit image 3 thereon. 4 is an image detector for detecting the projected slit 3, and is, for example, a TV camera.

FIG. 2 is an explanatory diagram of the prior art closest to the present invention. FIG. 2a shows an example of an output image from the image detector 4. In this figure, the bright parts of the slit image are drawn in black. The slit image optically detected in this manner is a two-dimensional optical image having brightness and darkness.
In order to realize automatic measurement and automatic inspection using this optical image, the optical cutting line (waveform) is extracted from this,
It needs to be processed electrically. When detecting the optical image in Fig. 2a with a TV camera, for example, the TV
If one scanning line of the camera is indicated by a broken line 5, its video signal 6 is shown in FIG. 2b. The video signal V reaches its maximum value at the position y=Yi where the scanning line 5 crosses the slit image.
Has Vmax. Therefore, for each scanning line within the detection range, the y-coordinate Y at which the video signal has the maximum Vmax
By finding , one cutting line can be extracted as shown in Figure 2c. 2 with bright and dark like this
If a one-dimensional optical cutting line can be extracted from a dimensional image, it can then be displayed on a monitor or judged by an automatic inspection circuit.

However, this conventional technology is based on the premise that the light-cut image always exists with appropriate brightness, and some parts of the light-cut image may become blind spots due to the shape of the object. Alternatively, if the object has a partially mirrored surface and the surface is in a direction that allows the projected light to enter the image detector in a specular reflection state, the disadvantage is that the original light cutting line cannot be detected. have. As an example, FIG. 3 shows video signals of two scanning lines. Figure 3a is an example of a video signal that detects a blind spot when the object is viewed from the image detector, but the brightest part of the light-cut image that should originally exist does not exist, and as a result, Among the noise in the video signal, the position Y' at the moment of the highest output is erroneously detected as the position of the optical cutting line. Figure 3b shows a case where the object is a mirror surface and the slit projection light enters the image detector in a specular reflection state, the output of the image detector is saturated, and at the maximum value (saturation value) the video signal is flat. This becomes a burden and prevents correct detection of the y-coordinate.

As described above, in the conventional technology, when the optically sectioned image is interrupted or conversely is too bright and the image detector is saturated,
This method has the disadvantage that the optical cutting line cannot be extracted correctly.

A first object of the present invention is to provide an optical section line detection device that can extract an uninterrupted section line even if the object to be detected is partially mirror-like.

The first feature of the present invention is that the maximum value of the video signal is detected and the position signal Y on the scanning line where the maximum value is detected is output. When exceeding the set value V ₁ close to the detector saturation value, this set value V ₁
The two position signals Y on the scan line coincident with ₁ and
The purpose is to output the average value Y' of _Y2 in priority to the position signal.

In other words, if the video signal exceeds the set value V ₁ , the video signal will exceed the set value on that scanning line.
The video signal and the set value V ₁ should match at two points: when exceeding V ₁ from bottom to top and when passing from top to bottom. Therefore, these two positions Y ₁
The original cutting line exists between and Y ₂ . Therefore, the average value of position signals Y ₁ and Y ₂ Y′ = (Y ₁ + Y ₂ )/
2, the original cutting line can be detected.

A second object of the present invention is to
To provide an optical cutting line detection device that does not cause false detection even if there is a blind spot.

A second feature of the present invention, in addition to the first feature described above, is that when the maximum value of the video signal is less than the second set value _V2 , the output of the position signal Y is canceled.

That is, the maximum value of the video signal, which is less than the low set value _V2 due to the blind spot of the detection target, has nothing to do with the original cutting line. Therefore, this position signal Y is erased and outputted as zero or undefined to prevent erroneous detection.

FIG. 4 shows the basic configuration of an embodiment of the present invention.
The light cutting and extraction circuit receives the video signal V from the image detector,
The set values V ₁ , V ₂ (V ₁ > V ₂ ) and the trigger signal Hd for each scan of the image detector (horizontal synchronization signal in the case of a TV camera) are input, and the maximum value position detection circuit 7 and center position detection are performed. It is composed of a circuit 8 and a selection circuit 9.

As illustrated in Fig. 5a, the function first detects the maximum value position when the maximum value Vmax of the video signal is within the range of the first and second set values _V1 and _V2 . The y position Y is determined by the circuit 7. Further, when Vmax is larger than _V1 (in the case of FIG. 5b), the center position detection circuit 8 first detects that V=
Y position Y ₁ becomes V ₁ , finally y becomes V=V ₁
Find the position Y ₂ and further find the center position by setting Y′=(Y ₁ +Y ₂ )/2. During one scan, if V in the circuit 8 becomes V ₁ or more, the selection circuit 9 outputs the output of the circuit 8; on the other hand, if V does not become V ₁ or more, the selection circuit 9 The output of the circuit 7 is outputted as the position of each optical cutting line.
Further, if V does not exceed V ₂ during one scan, the selection circuit 9 outputs zero or an undefined output.

The embodiment shown in Fig. 4 is described in more detail in Fig. 6.
It is a diagram. The details of the operation will be explained in more detail using FIG. 6.

The maximum position detection circuit 7 includes a peak holder 10,
It is composed of a comparator 11, a one-shot circuit 12, an AND circuit 13, a register 14, a comparator 16, and a flip-flop 17. on the other hand,
The center position detection circuit 8 includes a comparator 18, a flip-flop 19, and one-shot circuits 20, 2.
1, a _Y1 register 22, a _Y2 register 23, and an AND circuit 24. Also, y at each moment
It has a counter 15 to know the position. In the maximum position detection circuit 7, the video signal V enters a peak holder 10, which holds the peak value of V up to a certain moment during one scan. Comparator 11 compares this held peak value with V at that moment, and outputs a signal to one shot circuit 12 when V becomes greater than the held peak value by a predetermined value or more. On the other hand, V is compared with V ₂ in a comparator 16, and outputs when V≧V ₂ . By ANDing this with the output of the one-shot circuit 12 in an AND circuit 13, it is possible to detect the moment when V≧V ₂ and V reaches its peak. This is used as a load signal for the register 14, and the instantaneous value of the counter 15, which is reset by the trigger signal Hd, is stored in the register 14.
Therefore, at the end of one scan, the video signal V holds the y-coordinate position Y where the maximum value Vmax is shown.

In the center position detection circuit 8, the video signal V is compared with a set value _V1 by a comparator 18, and its output is input to the set side S of a flip-flop 19. Note that the flip-flop 19 is reset by the trigger signal Hd. Therefore, the one-shot circuit 20 initially performs V≧ in one scan.
Detect the moment when V ₁ . Add this to register 22
By using this as a load signal, the register 22 holds the position Y ₁ on the y coordinate where V≧V ₁ first. On the other hand, the one-shot circuit 21 detects the instant when V≧V ₁ no longer holds, and if this is used as a load signal for the register 23, the register 23 will contain y when V≧V ₁ no longer holds at the end of one scan. Position _Y2 on the coordinates is held. 24 is an average value circuit that calculates Y'=(Y ₁ +Y ₂ )/2.

The output of flip-flop 19 can be used to detect whether the condition V≧V ₁ existed during one scan. Furthermore, since the flip-flop 17 uses the trigger signal Hd as a reset signal and the output of the comparator 16 as a set signal, it can be used to detect whether the case of V≧V ₂ exists during one scan. Therefore, in the selection circuit 9, these are used as condition signals, and V
If ≧V ₁ exists, the hold value Y′ of 24 is
If V ₂ <V≦V ₁ , hold value Y of 14,
If there is no case where V≧V ₂ , a signal representing zero or indeterminate is output.

In this embodiment, the details of the image detector 4 are not mentioned, but it may be a TV camera, a secondary solid-state imaging device, a combination of a one-dimensional solid-state imaging device and an optical scanning method, a photomultiplier tube, etc. It may be any combination of a light receiver and an optical scanning method.

In addition, as for the optical configuration of the light section method, oblique illumination and oblique detection are illustrated in Fig. 1, but this is not possible with any configuration such as illuminating from a direction perpendicular to the surface to be measured and detecting from an oblique or horizontal direction. It's okay to be.

Furthermore, although the embodiments shown in FIGS. 4 and 6 are illustrated as having dedicated hardware for achieving each means, these means can all be processed by a program using a microcomputer. Can be done.

According to the present invention, it is possible to prevent erroneously extracting a light section line even when the image detector is saturated because the light section image is too bright. Further, according to a preferred embodiment of the present invention, there is no possibility of false detection due to blind spots in the video signal. in this case,
Although the photosection line is not extracted in areas darker than V ₂ ,
This is better than false detection due to noise.
This is desirable for automatic shape measurement and automatic shape inspection.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the optical system configuration of the light sectioning method, FIG. 2 is a diagram explaining the function of a conventional technique similar to the present invention, FIG. Figure 4 is a diagram showing the basic configuration of an embodiment of the present invention, Figure 5 is a diagram explaining the functions of an embodiment of the invention, and Figure 6 is a diagram showing the specific configuration of an embodiment of the invention. It is. 1...observation target, 2...slit floodlight, 3...
...Projected slit, 4... Image detector (TV camera), 5... Scanning line, 6... Video signal, 7...
Maximum value position detection circuit, 8... center position detection circuit,
9...Selection circuit, V...Video signal (same as 6),
V ₁ ...First set value, _V2 ...Second set value, Hd
...Trigger signal.

Claims (1)

[Claims] 1. A means for projecting slit light onto a printed board;
an image detector that detects a light section image obtained by the slit light; and an image detector that performs multiple scans on the light section line, and for each scanning point, an image detector that detects a light section image obtained by the slit light. In an optical cutting line detection device comprising a means for detecting the maximum value of a video signal, and a maximum position outputting means for outputting a position signal on a scanning line where the maximum value is detected as a point on the optical cutting line on the scanning line, each For scanning points, the video signal is the set value.
When V ₁ is exceeded, the average value of the two position signals Y ₁ and Y ₂ on the scanning line that matches this set value V ₁ is given priority to the maximum position output means and output as a point on the optical cutting line on the scanning line. An optical cutting line detection device characterized in that it is provided with means for detecting. 2 The maximum position output means outputs the second set value V ₂
2. The optical cutting line detection device according to claim 1, further comprising means for erasing an output below the threshold.