JPH05296745A - Form measuring device - Google Patents

Abstract

PURPOSE:To provide a form measuring device that is able to perform a job for form measurement in a short time. CONSTITUTION:A form measuring device illuminates a surface of solder S from different angles as selecting plural pieces of light emitting diodes 2 optionally, photographing a light regularly reflected on the surface of the solder S, and it seeks the position of an image of regular reflected light from the secured image, thereby measuring a three-dimensional form of the solder S. Then, plural pieces of these light emitting diodes 2 are lighted simultaneously, illuminating the solder S zonally, and the secured image is divided into grid form, forming plural pieces of picture domains, and partial inclination information of the solder S predetermined to each image domain is made to correspond thereto, the form of the solder S is operated on the basis of each brightness of these image domains and the inclination information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring method, and more particularly to a shape measuring apparatus for measuring an object to be measured having a mirror surface such as solder for joining electronic parts on a substrate.

[0002]

2. Description of the Related Art Conventionally, the inspection of the soldering state of electronic parts has mainly been based on visual inspection. In recent years, in order to abolish such manual work, an inspection device and a shape measuring device for automation have been developed.

As an apparatus for measuring the shape of solder, there is, for example, one described in Japanese Patent Application No. Hei 2-239909 by the present applicant. That is, in this type of shape measuring apparatus, for example, a cover having a large number of LEDs inside is used to cover the electronic components, and the LEDs are turned on one by one. Then, the shape measuring device reflects the light of the LED on the surface of the solder and takes in the specularly reflected light into the camera. The shape measuring principle of the above-described shape measuring apparatus will be described with reference to FIGS. 8A and 8B and FIGS. 9A and 9B.

First, the light source (LED) irradiates the measuring object O with light, and the image at this time is picked up by the image pickup device P. The captured image captures the light specularly reflected on the solder surface. Then, a bright point in this image is obtained as tilt information from the positional relationship between the light source and the imaging device. Therefore, the information on the inclination is obtained by the following equation. Θ _i = 90− (θ _j + θ _i ) / 2 That is, from the predetermined incident angle θ _{i of} light with respect to the measurement object O of the light source and the angle θ _j of the image pickup device P, the bright point of the imaged image is determined. The inclination θ is obtained.

Next, the position of the light source is changed, and the changed image is captured by the image pickup device P. At this time, by changing the position of the light source, the incident angle of light with respect to the measuring object O is changed to θ _{i + 1} . That is, the inclination θ _{i + 1} of the bright point of the image captured at this time is obtained by the following equation. Θ _{i + 1} = 90− (θ _j + θ _{i + 1} ) / 2 Hereinafter, similarly, Θ ₃ , Θ ₄ , ..., Θ _x are obtained.

Next, the shape of the surface O of the object to be measured is obtained by obtaining the inclinations Θ ₁ , Θ ₂ , ..., Θ _x . When measuring the shape, information in the height direction is necessary. Here, the outer shape of the measurement object is expressed by the equation z = f (x, y), where z is the height of an arbitrary coordinate (x, y). This equation can be obtained by integrating the slope. Next, a specific work for measuring the shape of the solder will be described based on FIGS. 9 to 13.

FIG. 9 shows an example of bright spots generated on the surface of the solder S. In the figure, symbols A to D indicate bright points. These bright points A to D are lit L
As the EDs are switched, they are generated one by one along the extending direction of the lead R.

First, when the point A appears, the center of gravity (representative point) G _{1 of} the point A and the inclination Θ ₁ formed by the point A are obtained. When the bright points B to D of the other LEDs appear, the centers of gravity G _{2 to} G _{4 of} the respective points and the inclinations Θ _{2 to} Θ ₄ formed by the respective points are similarly obtained. Then, when not only four points A to D but also five or more measurement points are set, the centers of gravity G ₅ , G ₆ , ... And the inclination Θ ₅ , depending on the number of measurement points.
Θ ₆ , ... Is required. In addition, the region where the inclination is 0, that is, the substrate surface is, for example, the boundary position G ₀ between the solder S and the substrate
It is determined based on.

Here, in FIG. 9, the solder S is raised on the surface of the substrate, extends along the protruding direction of the lead R, and inclines low as it goes away from the tip of the lead R. ..

In FIG. 9, G ₀ and G ₁ , G ₁ and G ₂ , ... Are not connected. Therefore, the midpoint C between G ₀ and G _1
0, G ₁ and the midpoint C ₁ of G _2, G ₂ and the middle point C ₂ with G _3, ... are sequentially calculated. Here, assuming the inclination of the surface from C ₁ to C ₂ to be Θ ₂ , the surface shape of the solder S is measured. Here, the length from C ₀ to C ₁ is L ₁ , the length from C ₁ to C ₂ is L ₂ , .... At this time, the height Z ₁ of C ₁ is calculated by the following formula. Z ₁ = L ₁ × tanΘ ₁ below, the height Z ₂ of C ₂ is calculated by the following equation. _{Z 2 = L 2 × tanΘ 2} + Z 1 Eventually, the height Z _i of C _i is calculated by the following equation.

By connecting the detection results, the cross-sectional shape of the solder S can be calculated as shown in FIG. This Figure 1
At 0, the LED row in the same direction as the lead R was sequentially turned on, but by turning on the other LED rows, the overall shape of the solder S is detected as shown in FIG. You can also

Further, as shown in FIG. 12, the image data may be divided into a grid pattern. In this case, the light intensity of a region divided in a grid pattern is calculated for each image, and the inclination Θ obtained from the position of the LED corresponding to the image with the brightest point is set as the inclination of the region. After that, the data of this inclination
The height information is calculated from the data as shown in FIG. 12, and the shape as shown in FIG. 13 is calculated.

[0013]

By the way, in the conventional shape measuring apparatus as described above, the partial shape and the height of the solder S are sequentially synthesized to obtain the overall shape of the solder S. Therefore, it is necessary to control the blinking of the LEDs one by one. Further, it takes much time to calculate the shape of the solder S, and it takes much time to measure the shape. An object of the present invention is to provide a shape measuring device capable of performing shape measurement in a short time.

[0014]

In order to achieve the above object, the present invention illuminates a measuring object from different angles while arbitrarily selecting a plurality of light sources, and specularly reflects the surface of the measuring object. In a shape measuring device for measuring the three-dimensional shape of an object to be measured by capturing light and determining the position of an image of specularly reflected light from the obtained image, a plurality of light sources are simultaneously turned on to illuminate the object to be measured in a band shape. Then, the obtained image is divided into a grid shape to form a plurality of image areas, and each image area is made to correspond to the partial inclination information of the measurement object that is determined in advance. It is to calculate the shape of the measuring object based on and. By doing so, the present invention provides
The purpose is to enable shape measurement in a short time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of the shape measuring apparatus of the first embodiment. LEDs 2 as light sources are arranged in a semi-spherical cover 1 that blocks ambient light every 10 degrees in the meridian direction and every 5 degrees in the latitudinal direction. The LEDs 2 ... Are connected to the control device 3 so that they can be turned on independently. Also,
Below the cover-1 is an X- as a mounting table for mounting a substrate.
A Y table 4 is provided. Also, this XY test
The bull 4 is controllably connected to the controller 3. Further, a camera 5 as an image pickup unit is arranged in the direction of the perpendicular of the cover-1. The camera 5 is connected to the image processing device 6 so that the captured image signal can be transmitted, and the image processing device 6 is also connected to the monitor 7 so that the processing result can be displayed on the monitor 7. The image processing device 6 is also connected so as to operate according to a command from the control device 3.

The control device 3 has a light control function for deciding the lighting order of the LEDs 2 ... And lighting the LEDs 2. Then, the control device 3 combines the LEDs 2 for each latitude and simultaneously turns on the LEDs 2 arranged in a line in the latitude direction. Further, each row of the LEDs 2 is lit in a ring shape, and the lighting of the LEDs 2 is switched in order from the upper side to the lower side of the cover-1.

The image processing device 6 has a function of taking in image data output from the camera 5 and storing it at a predetermined address. Further, the image processing device 6 divides the image data evenly in a grid pattern to form a plurality of image areas.
Further, the image processing device 6 associates the inclination information of the measuring object with each image area in advance, and calculates the shape of the measuring object based on the brightness of each image area and the inclination information. The image processing device 6 and the above-mentioned control device 3 constitute the arithmetic control means 8.

Next, the operation of the above-mentioned shape measuring apparatus using this apparatus will be described. First, the substrate 10 to which the electronic component 9 as the measurement object is soldered is placed on the XY table 4. When the substrate 10 is placed, the control device 3 moves to XY
The table 4 is driven so that the soldering portion comes to the center of the screen imaged by the camera 5. This is the substrate 10 in advance
Are positioned on the XY table 4, and the XY table 4 is driven based on the information.

After the object to be measured is aligned with the image pickup position in this way, the control device 3 causes the LED provided on the cover-1.
2 ... are lit in sequence from the top (in a ring shape) for each row on the same latitude. At this time, the images of the soldered portions illuminated for each row are sequentially captured by the camera 5.

The screens at this time are shown in FIGS. 2 (a) to 2 (d). FIG. 2A shows an image when, for example, the uppermost row of LEDs 2 ... Is lit. Illumination light is specularly reflected according to the relationship between the light source angle and the imaging angle, and a bright portion A is generated at the outer edge portion of the surface of the solder S. Similarly, when the LEDs 2 are switched and turned on, as shown in FIGS. 2 (b) to 2 (d),
Bright portions B to D occur depending on the inclination of the solder S.
The positions where these bright portions B to D appear change to a portion inside the solder S and closer to the axis of the lead R as the row of LEDs 2 ...

Next, the image thus picked up is the image data.
Data is transmitted to the image processing device 6 and stored therein. The image processing device 6 measures the shape based on the stored image data.

The image data stored here is divided into a grid pattern as shown in FIG. 3 to form a plurality of image regions (hereinafter referred to as regions) H _n (n = 1 to k). The areas H _n are set to have equal sizes and are composed of a plurality of pixels. Then, in FIG. 3, the overall size of the area H _n is a whole solder S in the entire region H _n, the substrate 10
And a part of the lead R are set to be included.

Next, the average value of the brightness of the pixels in each area H _n is obtained, and the area having the brightness equal to or higher than a predetermined value is selected. The area having the brightness equal to or higher than the predetermined value is a portion where light is specularly reflected based on the relationship between the light source angle and the imaging angle as described above, and the inclination thereof is calculated by the following formula. θ _n = 90− (θ _j + θ _i ) / 2 That is, from the angle of incidence θ _{i of the} light to the measurement object of the light source and the imaging angle θ _j , the inclination Θ of the region having the brightness equal to or more than the predetermined value _n is obtained.

Next, as shown in FIG. 3B, the image data captured by changing the light source angle is divided into a grid pattern at the same positions as in the previous case, and the brightness of the pixels in each region is divided. The average value of is calculated and the area having the brightness equal to or higher than a predetermined value is selected. By changing the angle of the light source, the incident angle of light on the measurement object is changed to θ _{i + 1} . That is, the inclination of this area is obtained by the following equation. θ _{n + 1} = 90− (θ _j + θ _{n + 1} ) / 2

Hereinafter, similarly, θ ₃ , θ ₄ , ..., θ _x will be obtained. FIG. 4 shows an example of the tilt information of each area H _i obtained as described above. The boundary between the solder S and the substrate a is obtained by using the epi-illumination mechanism built in the camera 5, and the region having the inclination of 0 ° is determined based on this boundary.

In order to obtain the height information from the tilt information, first, the center W _x of each area in the Y-direction row is calculated. Relative to the front of the inclination 0 ° in the region of a slope area (reference area), the distance to the area H ₁ L _1, the inclination theta ₁ Tosureba height Z ₁ region H ₁ under formula Can be calculated. Z ₁ = L ₁ × tan θ _{1 and} below Similarly, the height Z _m of the area having the tilt information is obtained.
Further, the height information is obtained by changing the region row in the Y direction by the above method.

A shape as shown in FIG. 5 is calculated from the height information of each area thus obtained. The height information of each area is created by superimposing the height of the area on the height information having a low value. That is, for example, the tilt information is 20
The height information of the area of 0 ° is a value obtained by adding the value of the height Z _i when θ _i = 20 ° to the height information of the area of which the inclination information is 10 °.

That is, in the shape measuring apparatus as described above, the LEDs 2 are controlled to be turned on collectively for each row on the same latitude, and are turned on in a ring shape in order from the top. Further, the image data stored in the image processing device 6 is divided into a lattice shape as shown in FIG. 3, and the average value of the brightness of the pixels in each area H _n is obtained. Then, an area having a brightness equal to or higher than a predetermined value is selected, and the inclination and height of the portion where light is regularly reflected are obtained.

Therefore, the individual blinking control of the LEDs 2 is not required, the blinking control of the LEDs 2 is simplified, and the three-dimensional shape of the solder S can be calculated in a short time. Although only one camera 5 is provided in this embodiment, for example, as shown in FIG.
By appropriately arranging ..., it is possible to prevent the occurrence of a blind spot in the measurement range.

Further, although only one object of shape measurement is described in this embodiment, this is for the purpose of simplifying the explanation of the operation. When actually measuring the soldering shape, windows can be set for a plurality of objects (for example, the lead portion of an electronic component), and the respective shapes can be measured at once. Since a plurality of shapes can be measured at once in this way, the measurement speed can be increased.

Further, in this embodiment, as the light source, the LEDs 2 ...
However, other illumination may be used as the light source. Further, for example, it is possible to divide the light flux of one or a plurality of light sources and guide the divided light flux to the cover-1 with the optical fiber. The present invention can be variously modified without departing from the scope of the invention.

[0033]

As described above, the present invention is obtained by illuminating the measuring object from different angles while arbitrarily selecting a plurality of light sources and imaging the light specularly reflected on the surface of the measuring object. In a shape measuring device for measuring a three-dimensional shape of a measurement target by obtaining a position of an image of specularly reflected light from an image, a plurality of light sources are simultaneously turned on to illuminate the measurement target in a band shape, and the obtained image is gridded. To form multiple image areas,
The shape information of the measurement target is calculated based on the brightness and the tilt information of each image region by associating the partial tilt information of the measurement target determined in advance with each image region. Therefore, the present invention has an effect that shape measurement can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

2A to 2D are explanatory views showing specularly reflected light when the illumination angle of an LED is sequentially changed.

3A to 3D are explanatory views showing a state in which image data is divided into a grid pattern.

FIG. 4 is an explanatory diagram showing a correspondence between a grid and inclination information.

FIG. 5 is an explanatory diagram showing an example of measurement results.

FIG. 6 is an explanatory diagram showing a modified example.

FIG. 7 is an explanatory diagram showing another modification.

8A and 8B are explanatory views showing the measurement principle.

FIG. 9 is an explanatory diagram showing an operation.

FIG. 10 is an explanatory diagram showing an operation.

FIG. 11 is an explanatory diagram showing an operation.

FIG. 12 is an explanatory diagram showing an operation.

FIG. 13 is an explanatory diagram showing an example of measurement results.

[Explanation of symbols]

1 ... Cover, 2 ... LED (light source), 3 ... Control device, 4 ...
XY table, 5 ... Camera (imaging means), 6 ... Image processing device, S ... Solder (measurement object).

Claims (1)

[Claims] 1. An object to be measured is illuminated from different angles while arbitrarily selecting a plurality of light sources, the light specularly reflected on the surface of the object to be measured is imaged, and an image of specularly reflected light is obtained from the obtained image. In a shape measuring device for determining a position and measuring a three-dimensional shape of the measurement object, a plurality of the light sources are simultaneously turned on to illuminate the measurement object in a strip shape, and the obtained image is divided into a grid shape. A plurality of image areas are formed, and each image area is made to correspond to partial inclination information of the measurement object determined in advance, and the shape of the measurement object is determined based on the brightness of each image area and the inclination information. A shape measuring device characterized by calculating.