JPH0156682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables inspection using only the brightness information of the object to be inspected, such as inspection of the soldered surface on the surface of a printed circuit board or inspection of connections between components and patterns mounted on a thick film module. The present invention relates to a three-dimensional shape detection device for detecting three-dimensional shapes that cannot be detected at high speed.

First, a conventional example will be explained with reference to the drawings.

Fig. 1 is a block diagram of an example of a conventional three-dimensional shape detection device, Fig. 2 is a partial perspective view of an example of the three-dimensional shape to be detected, and Fig. 3 is an image signal obtained by a television camera along the same optical cutting line. 4 are partial perspective views of other examples of the same three-dimensional shape to be detected.

This conventional device irradiates planar slit light SLT from a white light source 1 through a slit 2 and a condensing lens 3 onto the soldered part of a mounted component P on a printed circuit board PRT, as shown in FIG. To,
A projection light beam to the vicinity of the soldered portion S between the lead wire L and the land R of the component P is imaged by a television camera 5 (via the imaging lens 4) installed diagonally upward laterally.

The optical cutting line OSL of the projected light beam indicates the contour shape of the cross section of the part near the soldering part S that is irradiated with the slit light SLT, so by moving the sample table 6 in the x-axis direction, the lead By sequentially detecting the three-dimensional shape (soldering shape) in each part of the line L, the entire three-dimensional shape can be identified.

The screen captured by the television camera 5 is the third
As shown in the figure, the brightness of the part of the optical line broken OSL is high, and the brightness is high in the horizontal scanning direction of the television camera 5.
Since HSCN is from bottom to top (in Figure 3,
In order to improve the detection accuracy by increasing the resolution in the vertical direction), the shape of each optical cutting line OSL is determined by obtaining all position (time) data up to the brightest point for each screen. You can only get it if you apply it.

Therefore, it takes a considerable amount of scanning time just to detect one optical section line OSL, so it takes a very long time to detect the entire shape. for example,
Assuming that the scanning time is 20 ms per scanning line, it takes 20 ms x 256 ≒ 5 seconds to obtain a three-dimensional image of one object surface with 256 x 256 pixels and 8-bit gradation, which is a large practical problem. It becomes a constraint.

Furthermore, if the target object is axially symmetrical, the shape of the object can be detected without any problem by aligning the light spot scanning with the axially symmetrical direction and performing detection from one direction perpendicular to this up to half of the object. In the case of an object having a complex shape and not axially symmetrical, or in the case of a single object shape even though it is axially symmetrical, it is necessary to detect the entire surface of the object.

For example, in the case of an uneven object as shown in FIG. 4, the portion on the opposite side of the detection direction that is shadowed by the convex portion CVX cannot be detected. To solve this problem, the object must be rotated 180 degrees on a horizontal plane and detected again from the same direction, or a similar detection means must be provided on the opposite side. However, in the former case, the detection (inspection) time further increases, and in the latter case, it is difficult to physically arrange the detection means, and the cost increases significantly, resulting in practical problems. It was hot.

An object of the present invention is to eliminate the drawbacks of the prior art described above, improve detection time and detection performance, and provide an economical three-dimensional shape detection device.

The feature of the present invention is to irradiate the surface of an object with a laser beam that has passed through an optical polarizer to which ultrasonic excitation vibration has been applied, to scan a light spot in a straight line, and to ray the trajectory of this light spot on the surface of the object. is shunted into a reference light and a position detection light, and the ratio of each electrical signal subjected to photoelectric conversion is calculated for each light intensity, and this is used as the light cutting line signal to sequentially apply it to other positions on the object surface. There is provided a three-dimensional shape detection device configured to detect the three-dimensional shape of an object by obtaining the three-dimensional shape of the object.

Embodiments of the present invention will be described below based on the drawings.

FIG. 5 is a block diagram of an embodiment of the three-dimensional shape detecting device according to the present invention, and FIG. 6 is a three-dimensional shape diagram using optical cutting lines.

Here, 10 is the laser light source related to the laser scanning unit, 11 is the aperture lens, 12 is the optical deflector, 13 is the sweep oscillator, 14 is the condensing lens, and 15 is the photoelectric detection Imaging lens according to section 16
is the same half mirror, 17 is the same light spot position detection filter, 18 and 19 are the same condensing lens, 20 and 2
1 is the same photoelectric converter, 22 and 23 are the same amplifiers,
24 is a divider related to the image data input section; 25
is the same A-D (analog-digital) converter,
26 is a processing unit, 27 is a three-dimensional display related to the display unit, 28 is a pulse generator related to the sample moving unit, 29 is the same pulse motor, and 30 is the same sample table (for example, an XY table). .

First, the laser beam from the laser light source 10 is
The aperture lens 11 focuses the beam into a spot-like beam of an appropriate size, and the beam is incident on the optical deflector 12.

The optical deflector 12 uses the excitation vibration of an ultrasonic wave (of the same frequency as the sweep signal frequency of the sweep oscillator 13) generated by converting a high-frequency electric signal from the sweep oscillator 13 with a piezoelectric vibrator to deflect the acousto-optic medium. The refractive index of the laser beam changes periodically and diffracts the incident laser beam. Since the diffraction angle is proportional to the frequency of the ultrasonic wave, light deflection is possible.

That is, when the laser beam diffracted in this way is projected onto the surface of the three-dimensional object Q to be detected through the condensing lens 14, the light spot is scanned in a straight line (in the x-axis direction) on that part. It turns out.

Detection of the locus of this light spot scanning involves dividing the optical path of the imaging lens 15, which is provided in a direction perpendicular to the light spot scanning direction (x-axis direction), into two with a half mirror 16.
A light spot position detection filter 17 whose transmittance changes depending on the light spot position is inserted into one of them, and a condensing lens 18,
The output of the photoelectric converters 20, 21 (e.g., from a photomultiplier) is transmitted to the amplifier 2 through 19.
This is done by comparing the light spot intensities amplified to a desired level in steps 2 and 23.

First, the light spot intensity from the optical path in which the light spot position detection filter 17 is inserted is determined by the transmittance of the position detection filter 17 in proportion to the height of each light spot position projected onto the surface of the object Q. By making it change, it is detected as a detection electric signal Z corresponding to a position detection optical signal containing position information in the height direction on the surface of the object Q. Such a filter is
For example, it can be realized by optical glass having different thicknesses in the vertical direction, or by coating a flat glass with paint or the like having a predetermined transmittance by varying the thickness in the vertical direction.

Note that the output electrical signal X from the amplifier 23 on the optical path side into which nothing is inserted is an unprocessed signal corresponding to the light spot intensity at each position in the light spot scanning direction.

Since each of these signals Z and X changes depending on the surface condition of the object or changes in the light intensity of the light source, detection We are trying to improve performance.

That is, the ratio Z/X (optical section line signal) of the signals Z and 26.

The processing unit 26 controls the pulse generator 28 and operates the pulse motor 29 every time one optical cutting line signal is input.
in the direction perpendicular to the light cutting line (y-axis direction)
Move the test table 30 to .

The above-mentioned operations are performed in sequence, and the three-dimensional display 27 is able to display the three-dimensional shape three-dimensionally as shown in FIG. can.

In the above embodiment, detection is performed from a direction perpendicular to the light spot scanning direction, but it is not necessarily perpendicular and does not necessarily prevent detection from other directions.
Furthermore, detection is possible not only from one direction but also from two or more directions.

FIG. 7 is a block diagram of the main part of another embodiment of the three-dimensional shape detection device according to the present invention, and shows a convex portion.
This makes it possible to detect CVX from two opposite directions that shadow each other.

In this embodiment, each photoelectric detection unit 22A, 23A (in the implementation of FIG. 5, an imaging lens 15, a half A mirror 16, a position detection filter 17, condensing lenses 18, 19, photoelectric converters 20, 21, and amplifiers 22, 23) are provided, and a laser scanning section 10A (in the embodiment shown in FIG. 5, a laser light source 10, (corresponding to the aperture lens 11, optical deflector 12, sweep oscillator 13, and condensing lens 14), and the respective signals Z and The three-dimensional shape of the whole image can be detected by inputting the three-dimensional shape separately using switches 24a and 24b.

In each of the above embodiments, the optical deflector can scan the light spot at a sweep frequency of about 15 kHz, so the detection time of the optical cutting line is approximately 70 μs/line, compared to 20 ms/line in the conventional example described above. The speed can be increased by approximately 300 times compared to the conventional method, and the detection performance will be significantly improved.

In addition, when multiple photoelectric detection sections are provided,
As mentioned above, it is possible to detect three-dimensional shapes with complex unevenness, and it can also be applied to visual recognition of robots and automation of three-dimensional shape inspections that cannot be inspected using black and white grayscale images.

As described above in detail, according to the present invention, it is possible to implement an economical three-dimensional shape detection device that significantly improves detection time and detection performance, and the effects are remarkable.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an example of a conventional three-dimensional shape detection device, Fig. 2 is a partial perspective view of an example of the three-dimensional shape to be detected, and Fig. 3 is an image signal obtained by a television camera along the same optical cutting line. 4 is a partial perspective view of another example of the same three-dimensional shape to be detected, FIG. 5 is a block diagram of one embodiment of the three-dimensional shape detection device according to the present invention, and FIG. FIG. 7, which is a three-dimensional diagram using lines, is a block diagram of the main parts of another embodiment. 10... Laser light source, 11... Aperture lens,
12... Optical deflector, 13... Sweep oscillator, 14...
... Condenser lens, 15 ... Image forming lens, 16 ... Half mirror, 17 ... Light spot position detection filter, 1
8, 19... Condenser lens, 20, 21... Photoelectric converter, 22, 23... Amplifier, 24... Divider,
25...A-D converter, 26...processing device, 27
... Three-dimensional display, 28 ... Pulse generator, 29 ... Pulse motor, 30 ... Sample table, 10A ... Laser scanning section, 22A, 23A ...
...Photoelectric conversion section, 24a, 24b...switch.

Claims (1)

[Scope of Claims] 1. Laser scanning means for irradiating a laser beam passed through an optical deflector onto the surface of an object whose three-dimensional shape is to be detected to scan a light spot on the part; Means for shunting the reflected light into two systems; and a light spot position that receives one of the shunted reflected lights and changes the light transmission intensity in accordance with the light spot position in a direction perpendicular to the light spot scanning of the object. means for obtaining light spot position detection light through a light intensity conversion element; and photoelectric detection means for using the other shunted reflected light as a reference light and converting the reference light and the position detection light into corresponding electrical signals. , means for determining an electrical signal ratio corresponding to the position detection light and reference light, and means for converting the signal ratio into an analog-to-digital signal as an optical cutting line signal;
sample moving means for sequentially moving the object in a direction orthogonal to the light spot scanning direction and the light spot position direction for each light section line signal; A three-dimensional shape detection device characterized by having means for obtaining shape information. 2. The three-dimensional shape detection device according to item 1, characterized in that photoelectric detection means are provided in each of two directions perpendicular to the light spot scanning direction or in a plurality of directions intersecting with the light spot scanning direction. 3. A three-dimensional shape detection device characterized by performing recognition processing of a three-dimensional shape of an object based on the analog-to-digital converted digital signal.