JPS58201006A - Detector of three-dimensional shape - Google Patents

Abstract

PURPOSE:To shorten detecting time and to improve detecting performance by branching the reflected light of a laser beam from the surface of a material into two systems and detecting the three-dimensional shape of the subject from the ratio of electric signals of both systems. CONSTITUTION:The titled detector is constituted by a laser light source 10, a polarizer 12, a sweeping oscillator 13, focusing lenses 14, 18, 19, an image formation lens 15, a half mirror 17, an optical point position detecting filter 17, a photoelectric converter 20, 21, a divider 24, a processing part 26, a three-dimensional display 27, and a pulse generator 28. In said configuration, a laser beam is diffracted by the polarizer 12, the optical path of the image formation lens 15 which is reflected by the surface of the object is divided into two optical pathes by the half mirror 16 and these are detected as electric signals Z, X respectively. The divider 24 finds Z/X, the processing part 26 outputs each light cutting line signal and the display 27 displays the three-dimensional shape of the object.

Description

[Detailed Description of the Invention] ,' The present invention performs inspection using only the brightness information of the inspection target, such as inspection of solder surfaces on a printed circuit board or connection inspection 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 according to the drawings.

FIG. 1 is a block diagram of an example of a conventional three-dimensional shape detection device, and FIG. 2 is a partial perspective view of an example of the three-dimensional shape to be detected.
FIG. 3 is an image signal diagram of the same optical cutting line taken by a television camera, and FIG. 4 is a partial perspective view of another example of the same three-dimensional shape to be detected.

This conventional device uses a light source 1 of white light to pass a slit 2.
A planar slit light SLT is irradiated through the condensing lens 3, and the projected light beam is directed diagonally horizontally upward toward the vicinity of the soldering part S between the lead wire and the land R of the component P, as shown in Fig. 2. An image is captured by an installed television camera 5 (via an imaging lens 4).

The optical cutting line O8L 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, By sequentially detecting the three-dimensional shape (the shape of the solder) in each part of the lead wire, the overall three-dimensional shape can be identified.

As shown in FIG. 3, the screen imaged by the television camera 5 has high brightness at the portion of the light beam break O8L, and the horizontal scanning direction H8CN of the television camera 5 is "2" from the bottom (in FIG. 3). , in order to increase the resolution in the vertical direction and improve the detection accuracy), the shape of each optical cutting line OSL is determined by calculating the data for the entire position (C time) up to the brightest point for each screen. can be obtained for the first time.

Therefore, it takes a considerable amount of scanning time just to detect one optical cutting line O8L, so it takes a very long time to detect the entire shape. for example.

If the scanning time is 20 m5 per scanning line, obtaining a three-dimensional image of one object plane with 256 x 256 pixels and 8-bit gradation requires a time of 20 m5 x 256'' - i5 seconds, which is a major practical limitation. .

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 if 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 1800 times 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, detection (inspection)
The time required is further increased, and in the latter case, it is difficult to physically arrange the detection means, and the cost is significantly increased, which is a practical problem.

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 that a laser beam to which ultrasonic excitation vibration is applied and passed through an optical polarizer is irradiated onto the object surface to scan a light spot in a straight line, and the light beam of the trajectory of this light spot on the object surface is 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.

An embodiment of the present invention will be described below with reference to 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 a laser light source related to the laser scanning section, 11
12 is the same aperture lens, 12 is the same optical deflector, 13 is the same sweep oscillator, 14 is the same condensing lens, 15 is the imaging lens related to the photoelectric detection section, 16 is the same half mirror 117 is , the same light spot position detection filter, 18.19 the same condensing lens, 20°21 the same photoelectric converter, 22.23 the same amplifier, 24 the divider related to the image data input section, 25 is the same A-DC analog-to-digital) converter, 26 is,
The processing unit 27 is a three-dimensional display related to the display unit, 2
8 is a pulse generator related to the sample moving unit; 21j is the same pulse motor; 30 is the same sample table (for example, an XY table).

First, a laser beam from a laser light source 10 is focused by an aperture lens 11 into a spot-shaped beam of an appropriate size, and is incident on an optical deflector 12 .

The optical deflector 12 converts the high frequency electrical signal from the sweep oscillator 13 using a piezoelectric vibrator to generate an ultrasonic wave (sweep oscillator 1
The refractive index of the acousto-optic medium changes periodically due to the excitation vibration of the same frequency as the sweep signal frequency of #3), causing the incident laser beam to diffract. 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 laser beam is projected in a straight line (in the X-axis direction) for that part.
Light spot scanning will be performed.

The detection of the locus of this light spot scanning is carried out by 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 by a half mirror 16; A light spot position detection filter 17 whose transmittance changes according to ) output to amplifier 2
This is done by comparing the light spot intensities amplified to the desired level in step 2.23.

First, the light spot intensity from the optical path in which the light spot position detection filter 17 is inserted is 1. For example, the transmittance of the position detection filter 17 is proportional to the height of each light spot position projected on 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 can be realized, for example, by using optical glass that has different thicknesses in the vertical direction, or by coating flat glass with paint or the like having a predetermined transmittance by varying the thickness in the vertical direction. be able to.

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, the signal ratio Z/X is taken to compensate for and normalize the above conditions and changes, and detection We are trying to improve performance.

That is, the ratio Z/X (optical section line signal) of the above-mentioned signals Z and Part 26
Enter.

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

The above operations are performed in sequence, and the three-dimensional display 27 is able to three-dimensionally display the three-dimensional shape 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 prevent detection from other directions. can also be detected.

FIG. 7 is a block diagram of the main parts of another embodiment of the three-dimensional shape detection device according to the present invention, in which a convex portion (9) is detected from two opposite directions that shadow each other with respect to the CVX. It is possible.

In this embodiment, a convex portion CV of a three-dimensional object Q to be detected is
Each photoelectric detection unit 22A, 23A is placed in two opposite directions that shadow each other with respect to Transducer 20.21 and amplifier 22.
23), and a laser scanning unit 10A (corresponding to the laser light source 10, aperture lens 11, optical deflector 12, sweep oscillator 13, and condenser lens 14 in the embodiment shown in FIG. 5). Detects the optical cutting line of the object, and divides the respective signals Z and is possible.

In each of the above embodiments, the optical deflector is capable of scanning a light spot at a sweep frequency of about 15 kHz, for example, so the detection time of the optical cutting line is about 70 μS/line, compared to 20 m5/line of the conventional example described above. On the other hand, 10) it becomes possible to increase the speed by about 300 times, and the detection performance is greatly improved.

In addition, when multiple photoelectric detectors are installed, it becomes possible to detect 3D shapes with complex unevenness as described above, which is useful for visual recognition of robots and 3D shape inspection that cannot be performed with black and white gradation images. It can also be applied to automation, etc.

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 also improves detection performance, and its effects are remarkable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of a conventional three-dimensional shape detection device, and FIG. 2 is a partial perspective view of an example of the three-dimensional shape to be detected.
Fig. 3 is an image signal diagram of the same optical cutting line taken by a television camera, Fig. 4 is a partial perspective view of another example of the same three-dimensional shape to be detected, and Fig. 5 is a three-dimensional shape detection device according to the present invention. FIG. 6 is a block diagram of an embodiment of the present invention, and FIG. 6 is a three-dimensional shape diagram of the embodiment. FIG. 7 is a block diagram of the main parts of another embodiment (11
) be. 10... Laser light source, 11... Aperture lens, 12
... Optical deflector, 13 ... Sweep oscillator, 14 ... Condenser lens, 15 ... Image forming lens, 16 ... Half mirror 117 ... Light spot position detection filter, 18.19.
...Condensing 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, IOA... Laser scanning unit, 22A , 23A, . . . photoelectric conversion section b 24
a #24 b...Switch. Agent Patent attorney Kosaku Fukuda (and 1 other person) (12) 1st Sen Figure 3 #Dokuni

Claims (1)

[Claims] 1. A laser beam to which ultrasonic excitation vibration is applied and passed through an optical deflector is irradiated onto the surface of an object whose three-dimensional shape is to be detected, and a light spot is scanned in a straight line on the relevant part. A position detection light and a position detection light obtained by branching the reflected light from the surface of the object into two systems and changing the light intensity from one of them according to the position of the light spot in the height direction of the object. A photoelectric detection unit obtains electrical signals corresponding to each of the reference lights directly without any processing from the other side, and calculates the ratio of the electrical signals corresponding to the position detection light and reference light, and uses this as a light cutting line signal for the corresponding one. An image data input section that converts and outputs digital signals, a processing section that processes and analyzes the digital signals, and performs necessary control over each section; A three-dimensional shape comprising: a sample moving unit that sequentially moves the object in the direction; and a display unit that displays information on the three-dimensional shape of the object based on each optical cutting line signal from the processing unit. Detection device. 2. In the item described in claim 1. A three-dimensional shape detection device configured by providing photoelectric detection sections in each of two directions perpendicular to the light spot scanning direction or in a plurality of directions intersecting the light spot scanning direction.