JPH04166709A - Surface-state observing apparatus - Google Patents

Abstract

PURPOSE:To judge the surface state of the solid bounded by a curved surface by emitting the lights having the different colors from spot light sources in the directions corresponding to the different bearing angles and elevation angles from an object to be observed on the object under observation at the same time. CONSTITUTION:In a printed-board inspecting apparatus, the images of a positioning board 20S and a board under inspection 20T are picked up and compared. Whether each part 21T of the board 20T is correctly mounted and soldered or not is inspected. In this constitution, the lights having the different colors are generated from a plurality of spot light sources 28 and emitted on an object to be observed at the different incident bearing angles and incident elevation angles based on the control signal from a processing part 26 in a light projecting part 24 at the same time. The light sources 28 are arranged at the upper part of the inspecting position so that the light sources on dashed lines a1 - a5 are aligned in the same elevation angle and the light sources on dashed lines b1 and b2 are aligned in the same bearing angle.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to detecting the orientation of each curved surface element in a curved body consisting of a set of a large number of curved surface elements whose surface curved shapes are oriented in different directions. In particular, the present invention relates to a curved surface property observation device suitable for inspecting the shape of a soldered part of a component mounted on a printed circuit board.

<Prior Art> As a curved body having a multi-oriented curved surface, soldering of components mounted on a printed circuit board is a typical example of the surface shape of the part. Conventionally, this soldering part is inspected by visual inspection, and the soldering is in good or bad condition.
That is, the presence or absence of solder, amount, solubility, short circuit, poor continuity, etc. are determined by this visual inspection.

However, in such a visual inspection method, the occurrence of inspection errors is unavoidable, the judgment results vary depending on the person conducting the inspection, and there is a limit to the inspection processing capacity.

Therefore, in recent years, various automatic inspection devices that can automatically perform this type of inspection have been proposed. - By the way, the surface shape of a soldering part is a three-dimensional shape with three-dimensional expansion, and in order to inspect this, it is essential to be able to detect three-dimensional shape information.

FIG. 8 shows an example of an automatic inspection apparatus that satisfies this condition, in which a plate-shaped slit light l is irradiated from a light source such as a laser onto the soldering area on the board 2. By irradiating this slit light l, soldering is performed on the board 2 including the parts.
A light section line 3 that is distorted along the three-dimensional shape is generated on the surface of the , and a reflected light image of the light section line 3 is captured by an imaging device 4 to determine the distorted state of the imaged pattern. By checking, the soldering detects the three-dimensional shape of the part.

However, in the case of this inspection method, only the shape information of the portion irradiated with the slit light 1 is obtained, and it is difficult to grasp the three-dimensional shape of the other portions. Moreover, since the surface of the soldering part is not fixed with respect to the orientation direction or the vertical direction of the board 2, at least four combinations of the light source and the imaging device 4 are required, which makes the device complicated. , and requires high-precision assembly work.
There is a problem with not increasing costs.

Therefore, as a method to solve this kind of problem, the surface of the curved surface to be inspected is irradiated with light with different incident angles, and each reflected light image from the surface of the curved surface is imaged, and the curved surface is There is a method of detecting the orientation of each curved surface element. The principle of this method is one of three-dimensional image information detection [active sensing method].
It belongs to In other words, this method focuses on the fact that when a light beam with a certain pattern is projected onto an inspection object, the pattern of the reflected light beam obtained from the inspection object undergoes deformation corresponding to the three-dimensional shape of the inspection object. in,
This method estimates the shape of the object to be inspected from the deformation pattern.

FIG. 9 is a diagram explaining the principle of this method, and shows the positional relationship between an observation system consisting of a light source 5 and an imaging device 6, and a curved object 7 to be observed.

In the figure, when a light beam 8 is projected from a light source 5 onto the surface of a curved surface body 7 at an incident elevation angle i, a reflected light beam 9 at an angle i' (=i) enters the imaging device 6 placed directly above. detected. This means that it has been detected that the curved surface elements of the curved surface body 7 illuminated by the light beam 8 are oriented at an elevation angle of i with respect to the reference plane lO. Therefore, if the surface properties of the curved body 7 or the soldering are composed of a large number of curved elements oriented in different elevation angle directions like a surface, then
If a plurality of light sources with different incident elevation angles are used to project light onto the surface of the curved surface body 7, a group of curved surface elements corresponding to each incident elevation angle is detected by the imaging device 6, and thereby each curved surface element on the surface of the curved surface body 7 is detected. It is possible to detect whether the soldering is oriented at various elevation angles, that is, whether the soldering is due to the surface texture of the part.

Also, the light source 5 or the incident elevation angle is 2 from i + Δi to i − Δi.
If a beam of light 8 having a width of Δi is projected, a reflected beam of light 9 having a width corresponding to the width will be detected by the imaging device 6. That is, in this case, it is possible to detect a curved surface element having an elevation angle with respect to the reference plane lO or an angle having a width from 10 Δ1 to i−Δ1.

Furthermore, as shown in FIG. 1O, if the projector is configured with a plurality of light sources 11, 12, 13 having different elevation angles of incidence on the curved surface body 7, the angle of incidence of the light beams 14, 15, 16 from each light source can be adjusted. This means that curved surface elements with orientation can be detected in greater detail.

Based on the above principle, a device for inspecting the appearance of soldering parts using a plurality of annular white light sources has been proposed (Japanese Patent Application Laid-open No. 293657/1983).

Figure 11 shows the inspection principle.
Annular white light sources 17, 18.degree. 19 are arranged horizontally at different height positions with respect to the reference plane 10.

Now, the radius of each light source 17, 18, and 19 is rl.

(However, n = 1.2.3), the height with respect to the reference surface 1o, (n = 1.2.3), the incident elevation angle of each light beam to the curved surface body 7 is i, (n = 1.2゜3)
Therefore, each curved surface element having an elevation angle of 17 in the curved surface body 7 can be detected by the imaging device 6. At this time, since the size of the curved surface element is sufficiently small compared to the total optical path length from each light source 17, 18° 19 to the imaging device 6 via the surface of the curved surface body 7, the incident elevation angle, that is, the angle of incidence to be detected is determined by the following formula. What is necessary is to determine the elevation angle of the curved surface element.

In this inspection method, soldering is carried out using light sources 17, 18.
9 are turned on and off at different timings.

<Problem to be solved by the invention> However, with this method, not only is it not possible to inspect curved surface properties at high speed, but it also requires a large amount of memory and memory to store each image obtained at different light emitting timings. , a calculation device to process these images as the same visual field image, a control device to flash each light source momentarily, etc. are required, which is technically complex, and also increases cost and This poses an issue in terms of reliability.

This invention was made by focusing on the above problem, and is a curved surface property observation device that can observe the curved surface properties of curved objects such as soldering parts in a short time, and also reduces costs and improves reliability. The purpose is to provide

<Means for Solving the Problems> The present invention is a surface texture observation device that introduces a curved body to be observed into an observation position and observes the surface texture of the curved body, which includes a light projection device and an imaging device. It has The light projection device includes a plurality of point light sources that simultaneously project light of different colors, and each point light source is arranged in each direction corresponding to a different azimuth angle and elevation angle when viewed from the observation position. . Further, the imaging device is disposed directly above the observation position so as to be able to capture a reflected light image of the surface of the curved body.

<Operation> Since light of different colors is simultaneously projected onto the observation object from point light sources in each direction corresponding to different azimuth and elevation angles when viewed from the observation object, the imaging device captures the reflected light image from the surface of the curved object. can be obtained simultaneously for each color, and the surface properties of the curved object can be determined at high speed using the imaged pattern.

<Embodiment> FIG. 1 shows a schematic configuration of a printed circuit board inspection apparatus according to the present invention.

The board inspection apparatus of the illustrated example has each component 21 on the positioning board 2O3 obtained by imaging the positioning board 2O3.
Compare the parameters (judgment data) of the inspection area of S with the parameters (inspection data) of the inspection area of each component 21T on the substrate 2OT to be inspected obtained by transporting the substrate 20T to be inspected. The X-axis table section 22., is for inspecting whether each of these components 21T is correctly mounted and soldered. Y-axis table section 23. Light projecting section 24° imaging section 25. The configuration includes a processing section 26 and the like.

The X-axis table section 22 and the Y-axis table section 23 are each equipped with a motor (not shown) that operates based on a control signal from the processing section 26, and when driven by these motors, the X-axis table section 22 or the imaging section 25 in the X direction, and the Y-axis table section 23 or the conveyor 27 supporting the substrates 2O3, 20T is moved in the X direction.

These substrates 2O3 and 20T are imaged by the imaging section 25 while receiving irradiation light from the light projecting section 24.

The light projection unit 24 includes a plurality of point light sources 28 that generate light of different colors based on a control signal from the processing unit 26 and simultaneously irradiate the inspection target at different incident azimuths and elevation angles. , the luminous flux emitted from each point light source 28 is projected onto the substrate 2O3, 20T, and an image of the reflected light is obtained by the imaging section 25 and converted into an electrical signal.

FIGS. 2 and 3 show a specific example of this light projecting section 24, in which the above-mentioned point light sources 28 are arranged in a dotted manner on the inner surface of a hood 29 having a dome shape. The hood 29 has a bottom opening facing downward, and an imaging section 25 located in an opening 30 on the top surface.

The point light source 28 may be a white light source covered with filters of different colors, but is of course not limited to this as long as it can project light of different colors.

Each point light source 28 is arranged above the inspection position in each direction corresponding to a different azimuth angle and elevation angle when viewed from the inspection position, and in FIG. 3, - point chain #I a I
- Each point light source 28 on a s is located in the direction of the same elevation angle, - dotted chain line S, b2. The point light sources 28 above b, . . . are located in the same azimuth direction.

Note that the point light sources 28 do not necessarily need to be provided in all azimuth directions as in the above embodiment, but may be provided only in a specific range of azimuth directions, as shown in FIG.

In the case of this embodiment, the presence or absence and position of the curved surface element to be detected can be directly determined.

Further, when the point light source 28 is provided over all azimuth angles,
It is not necessary that all the point light sources 28 project light of different colors; for example, for a range of 90° in azimuth angle, each point light source 28 may be configured to project light of a different color, and the remaining For the angular range of the same point light source 28
A combination of these may be used repeatedly.

FIG. 5 shows the principle of detecting the azimuth angle of the surface of the inspection object 48, and shows the geometrical relationship between an arbitrary point light source 28 and the inspection object 48 viewed from above.

In the same figure, when a light beam 49 is projected from a point light source 28 onto the surface of an inspection object 48 at an incident azimuth angle of 49, the reflected light beam enters the imaging unit 25 located directly above the inspection object 48. detected.

Thereby, it is detected whether the curved surface elements in the inspection object 48 illuminated by the light beam 49 are oriented at an azimuth angle of j with respect to the coordinate axis 50.

Therefore, if the surface shape or soldering of the inspection object 48 is made up of many curved surface elements oriented in different azimuth directions like a surface, a plurality of point light sources 2 with different incident azimuth angles may be used.
8 onto the surface of the inspection object 48, the imaging section 25 detects a group of curved surface elements corresponding to each incident azimuth. This makes it possible to detect the azimuth angle at which each curved surface element on the surface of the inspection object 48 is oriented.

Also, whether the point light source 28 or the incident azimuth is j−Δj to j+Δj
If the beam 49 with a width of 2Δj is projected, a reflected beam 49 with a width corresponding to the width will be imaged. In this case, the azimuth with the coordinate axis 50 is A curved surface element having an angle of width up to Δj will be detected.

Thus, as shown in FIG. 6, if the light projecting unit 24 is configured by arranging the point light sources 28 in each direction corresponding to a different azimuth angle when viewed from the inspection object 48, the light flux 49 from each point light source 28 will be This means that curved surface elements with an orientation corresponding to the incident azimuth angle can be detected in greater detail.

Note that the principle of elevation angle detection has already been explained in the description of the conventional technology, and the same explanation will not be repeated here.

Next, the imaging section 25 is equipped with a color television camera 32 located directly above the inspection position, and the reflected light from the substrate 2O3 or 20T is converted into three primary color signals R, G, and B by this color television camera 32. and is supplied to the processing section 26.

The processing section 26 includes an A/D conversion section 33. Memory 38° Teaching table 352 Image processing section 34° Judgment section 36. X
, Y table controller 37° imaging controller 31
．． CRT display section 41. Printer 42. Keyboard 40.
Floppy disk device 43. Control unit (CPU) 3
9, and when in the teaching mode, the color signal R9G for the positioning board 2O3,
A color pattern formed by the reflected light of each colored light projected on a predetermined area of each component 21S that is in good soldering condition is detected, a judgment data file is created, and an inspection is performed. In the mode, color signals R, G, and B for the board to be inspected 20T are processed, similar color patterns are detected in predetermined areas of each component 21T on the board, and a data file to be inspected is created.

Then, this inspected data file and the judgment data file are compared, and based on the comparison result, the inspected board 2OT
For the above predetermined component 21T, it is automatically determined whether the soldering part is good or bad.

Figure 7 (1) shows the solder 44 when the soldering is good, Figure 7 (2) shows the solder missing, and Figure 7 (3) shows the solder 44 when the component is missing. The relationship between the cross-sectional form and the imaging patterns 45 to 47 in each case is shown in association with each other, and each imaging pattern 45 to 47
Since there is a clear difference between the two, it is possible to judge whether the parts are grown or not and whether the soldering is good or bad.

Returning to FIG. 1, when the A/D converter 33 is supplied with the color signals R, G, and B from the image pickup section 25, it converts them into analog and digital signals and outputs them to the control section 39. The memory 38 includes a RAM and the like, and is used as a work area for the control section 39. The image processing section 34 performs image processing on the image data supplied via the control section 39 to create the above-mentioned inspected data file and judgment data file, and supplies these to the control section 39 and the judgment section 36.

The teaching table 35 is connected to the control unit 3 during teaching.
When a judgment data file is supplied from the control unit 9, it is stored, and when the control unit 39 outputs a transfer request during inspection, the judgment data file is read out in response to this request and is sent to the control unit 39 or the judgment unit. 36 etc.

The determination unit 36 compares the determination data file supplied from the control unit 39 at the time of inspection with the data file to be inspected transferred from the image processing unit 34, and determines the quality of the board 2 to be inspected.
At 0T, it is determined whether the soldering condition is good or bad, and the determination result is output to the control section 39.

The imaging controller 31 includes an interface for connecting the control section 39 with the light projecting section 24 and the imaging section 25, and controls each point light source 2 of the light projecting section 24 based on the output of the control section 39.
Control is performed such as adjusting the amount of light of 8 and maintaining the mutual balance of the light outputs of each hue of the color television camera 32 of the imaging section 25.

The X, Y table controller 37 includes an interface for connecting the control section 39 with the X-axis table section 22 and the Y-axis table section 23, and controls the X-axis table section 22 and the Y-axis table section 23 based on the output of the control section 39. control.

The CRT display section 41 is equipped with a cathode ray tube (CRT), and when image data, judgment results, key manual data, etc. are supplied from the control section 39, they are displayed on the screen. When the printer 42 is supplied with the determination result etc. from the control unit 39,
This is printed out in a predetermined format. The keyboard 40 is equipped with various keys necessary for inputting operation information, data regarding the positioning board 2O3, data regarding the component 21S on this positioning board 2O3, etc., and the information and data input from this keyboard 40 are controlled. 39.

The control unit 39 includes a microprocessor, etc.
It operates according to the procedure described below.

First, when inspecting a new substrate to be inspected 20T, the control section 39 controls each section of the apparatus to turn on the light projecting section 24 and the imaging section 25 in order to execute teaching, and also sets the imaging conditions and data processing conditions. Arrange. Next, Y-axis table section 2
When the positioning board 2O3 is set on the controller 3, the controller 3
9 controls the X-axis table section 22 and the Y-axis table section 23 to position the positioning board 2O3, and then moves the imaging section 2
5 to image the positioning board 2O3. The three primary color signals R, G, and B obtained by this imaging operation are A/D converted by an A/D converter 33, and the conversion results are stored in a memory 38 in real time.

Accordingly, the control unit 39 transfers the image data corresponding to each hue from the memory 38 to the image processing unit 34, and the image processing unit 34 converts the image data of each hue into binary values using an appropriate threshold value for each hue. Detect the color pattern of the reflected light. The control unit 39 also controls the image processing unit 34 and checks the brightness of each part (electrode, etc.) in the imaged pattern of each component 21S to identify the position of the electrode and polarity mark of each component 21S. let

Thereafter, the control unit 39 creates a determination data file necessary for inspecting the board to be inspected 20T based on each of the color patterns and the identification results, and stores this in the teaching table 35. , end teaching.

Next, when shifting to the inspection mode, the control unit 39 takes in the date data of the day and the ID number (identification number) of the board to be inspected 20T from the teaching table 35 and the keyboard 40, and reads out the judgment data file from the teaching table 35. , and supplies this to the determination section 36.

Thereafter, the control section 39 checks whether the substrate to be inspected 20T is set on the Y-axis table section 23 after adjusting the imaging conditions and data processing conditions.

If set, the control unit 39 causes the image processing unit 34 to sequentially detect each color pattern and identify the electrodes and polarity marks as described above, and then compares each color pattern with the above identification results. Create a data file to be inspected based on this. The control unit 39 then transfers the inspected data file to the determining unit 36, compares the inspected data file with the determined data file, and determines whether the inspected board 2O
The quality of soldering is determined for a predetermined component 21T on the T, and the determination results are supplied to the CRT display section 41 and printer 42 for display and printing out.

<Effects of the Invention> As described above, the present invention configures a light projection device with a plurality of point light sources that simultaneously project light of different colors, and
Since each point light source is placed in each direction corresponding to a different azimuth and elevation angle when viewed from the observation position, the imaging device can simultaneously obtain images of reflected light from the surface of the curved surface for each color. The surface properties of a curved object can be determined at high speed using an imaged pattern. Also, unlike the conventional example of turning on and off each light source in chronological order, it does not require a large memory capacity, nor does it require calculations to combine images with time lags or control to determine the timing of the blinking of the light sources. and
The invention achieves remarkable effects such as reducing costs and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the overall configuration of a board inspection apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the configuration of the light projecting section, and FIG. 3 is an illustration showing the arrangement of point light sources. FIG. 4 is a bottom view of the light projecting section showing another arrangement of point light sources, FIGS. 5 and 6 are explanatory diagrams showing the principle of detecting the azimuth angle, and FIG. An explanatory diagram showing the relationship between the soldering condition and the imaged pattern, FIG. 8 is an explanatory diagram showing a conventional example,
FIG. 9 and FIG. 10 are explanatory diagrams showing the principle of detecting the elevation angle;
FIG. 11 is an explanatory diagram showing a conventional example. 24... Light projecting section 25... Imaging section 26.
... Processing unit 28 ... Point light source patent applicant
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Claims (1)

[Scope of Claims] A surface texture observation device for introducing a curved surface object to be observed into a predetermined observation position and observing the surface shape of the curved surface object, comprising: a light projection device and an imaging device; The light projection device includes a plurality of point light sources that simultaneously project light of different colors, and each point light source is arranged in each direction corresponding to a different azimuth angle and elevation angle when viewed from the observation position, The imaging device is a surface texture observation device that is arranged directly above the observation position so as to be able to capture a reflected light image of the surface of the curved object.