DE102010064640B3 - Method for measuring a measurement target - Google Patents

Abstract

There is provided a method of measuring a soldering area, comprising the steps of: irradiating a plurality of color illuminations onto a circuit board to obtain a plurality of color images; Creating a saturation map by means of a chroma information obtained from the color images of each color; Setting a soldering area in the saturation map by means of a light intensity information obtained from the color images of each color; Generating a saturation value for each color in the soldering area; Creating a variance map using the saturation information for each color and the saturation average for each color; and comparing a variance value on the variance map with a critical value to make a solder card showing the soldering area in which a solder is formed.

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

Embodiments of the present invention relate to a method for measuring a measurement target. In particular, embodiments of the present invention relate to a method of measuring a measurement target designed to increase accuracy.

DISCUSSION OF THE BACKGROUND

In general, at least one printed circuit board is used in an electronic device. The printed circuit board typically has a base plate, a pad part and a drive chip electrically connected to the pad part.

A terminal is disposed under the driver chip for electrical connection to the pad portion, and the terminal is typically electrically connected to the pad portion via a solder formed on the pad portion. Therefore, a method of manufacturing the circuit board necessarily includes forming the solder on the interface part.

A quantity of the solder formed on the pad part may affect the electrical connection between the pad part and the terminal. If the solder is formed too large, a short-circuit defect can occur between adjacent connection surface parts; if the solder is made relatively small, this can cause a poor electrical connection between the pad part and the terminal.

As described above, since the quantity of solder formed on the pad part can have a significant effect on the electrical connection between the pad part and the terminal, there is a need for a method of accurately measuring a quantity of the solder formed on the circuit board.

In general, methods for examining solder on printed circuit boards by means of color illuminations on the circuit board and their reflection from the US 2006/0291713 A1 and US 2006/0153439 A1 known.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method of measuring a measurement target configured to accurately measure a portion of the measurement target.

Embodiments of the present invention further provide a method of measuring a solder area configured to accurately measure a portion of a solder formed on a circuit board.

Embodiments of the present invention further provide a method for correcting the uniformity of each color before measuring a soldering area for each color, so that the accuracy of measurement of the soldering area increases.

Additional features of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

In one embodiment of the present invention, a method for measuring a measurement target on a printed circuit board is disclosed. The method comprises obtaining a three-dimensional height information of the printed circuit board by means of a first image which is photographed while grating pattern light is irradiated onto the printed circuit board by means of a first illumination unit, determining a first region protruding on the printed circuit board at a height greater than one or as a reference level, as a measurement target based on the obtained height information, obtaining color information of the printed circuit board by means of a second image which is photographed while light generated by a second illumination unit is irradiated onto the printed circuit board, setting the first color information of the first one Area determined from the obtained color information of the circuit board as a measurement target as Reference color information, and comparison of the reference color information with color information of a region from which the first region is excluded, for judging whether or not the measurement target is formed in the region except the first region.

The method may further comprise dividing the reference color information of the first area and the color information of the area excluding the first area into first and second clusters. The comparison of the reference color information with the color information of the area from which the first area is excluded for judging whether or not the measurement target is formed in the area from which the first area is excluded may check whether the second cluster is the one or not, and, if the second cluster belongs to the first cluster, the judgment that an area corresponding to the second cluster belongs to the measurement target area.

The first and second clusters may include a feature extracted from the obtained color information by a color coordinate system, the feature having hue and / or color saturation and / or light intensity.

The method may further include obtaining a second color information of a second area in which a predetermined comparison object is arranged to protrude on the circuit board based on the measured color information of the circuit board, obtaining a third color information of a third area in which the measurement target is not is formed, based on the measured color information of the printed circuit board, and the division of the first, second and third color information of the first, second and third area respectively into a first, second and third cluster. The comparison of the reference color information with the color information of the area from which the first area is excluded to judge whether or not the measurement destination is formed in the area except the first area may be to check whether color information of a predetermined area A portion on the circuit board from which the first, second and third areas are excluded, belongs to the first cluster, and if the color information belongs to the first cluster, the judgment that the measurement target is formed on the predetermined portion.

The method may further include obtaining visibility information based on N grid pattern lights in accordance with movement of a grid unit and comparing visibility information of the first area and visibility information of a area from which the first area is excluded to judge whether the measurement destination is in the area of which the first region is recessed, formed or not.

In a further embodiment of the present invention, a method for measuring a measurement target on a printed circuit board is disclosed. The method comprises obtaining three-dimensional height information and visibility information of the printed circuit board by means of a first image photographed while irradiating grating pattern light on the printed circuit board by means of a first illumination unit, determining a first area on the printed circuit board at a height which is greater as a measurement point by means of the obtained altitude information, and comparing first visibility information of the first area with second visibility information of a area from which the first area is excluded, for judging whether the measurement target is in the area of which the first area is excluded, is formed or not.

In still another embodiment of the present invention, a method of measuring a soldering area is disclosed. The method comprises irradiating a plurality of color illuminations onto a circuit board to obtain a plurality of color images, forming a saturation map by means of the obtained color images, and extracting a soldering area by the saturation map.

The irradiation of the color illuminations onto the printed circuit board to obtain the color images may include the irradiation of a red illumination, a green illumination and a blue illumination to obtain a red image, a green image and a blue image, respectively.

The creation of the saturation map by the obtained color images may include obtaining color tone information and / or saturation information and / or light intensity information for each color by color coordinate conversion of the color images and saturation map by saturation information for each color.

Extraction of the soldering area by the saturation card may include excluding a wiring pattern area and / or a dark solder resist area from the saturation map using the light intensity information for each color and setting the soldering area.

The extraction of the soldering area by the saturation map may include the production of a saturation value for each color in the soldering area, the creation of a variance map by means of the saturation information for each color and the saturation average for each color, and the comparison of a variance value on the variance map to create a solder card on which the soldering area is shown, in which a solder is formed. Each of the variance values for pixels can be obtained from the equation "Variance value for each pixel = abs (R-RA) + abs (G-GA) + abs (B-BA)". , R ',' G 'and' B 'are saturation information for each pixel, while' RA ',' GA 'and' BA 'are saturation average values for each color.

Prior to irradiating the color illuminations to the printed circuit board to obtain the color images, the method may further include irradiating the color illuminations on a target to obtain a plurality of illumination images for colors, obtaining a light intensity for each pixel with respect to each of the illumination images for colors, and setting a color Compensation ratio for each color corresponding to a ratio between the light intensity for each pixel and an arbitrary reference light intensity for each pixel. Before creating the saturation map by means of the obtained color images, the method may include compensating the color images by means of the compensation ratio for each color. The reference light intensity may correspond to an average light intensity of each of the color images.

Prior to irradiating the color illuminations to the circuit board to obtain the color images, the method may include irradiating the color illuminations on a solder formed on the circuit board to obtain a plurality of solder images for each color, obtaining a light intensity for each color of the solder based on each of the solder images each color, and setting a compensation ratio for each color of the solder according to a ratio between the light intensity for each color of the solder and an arbitrary reference light intensity. Prior to creating the saturation map using the obtained color images, the method may include compensating the color images by the compensation ratio for each color of the solder. The reference light intensity may correspond to an average light intensity of a plurality of soldering intensities for each color.

Prior to irradiating the color illuminations to the printed circuit board to obtain the color images, the method may include setting a compensation ratio for each color of the color illuminations to correct the color uniformity for the color illuminations and setting a compensation ratio for each color of a solder uniformity correction solder for the color illuminations. Prior to preparing the saturation map using the obtained color images, the method may include multiplying each color image by the compensation ratio for each color of the color illuminants and the compensation ratio for each color of the solder.

As described above, an area corresponding to a height greater than or equal to a predetermined reference height H1 is determined as a soldering area, and a color information of the soldering area is set as reference color information for comparing the color information of the soldering area with another area , An area corresponding to a height below the reference height H1, which may be omitted, is thus part of the soldering area, whereby the soldering area can be measured accurately.

In addition, although the solder is spread thinly on the base plate, which is common in the formation of a solder, the soldering area can be accurately measured.

In addition, when the color information of the first area AR1, a soldering area corresponding to a height greater than or equal to a predetermined reference height H1, and the color information of the second and third areas AR2 and AR3 are obtained and packaged in clusters a section whose integration into the soldering area is unclear can be assessed more clearly.

Furthermore, a soldering area can be more accurately determined by means of visibility information.

Furthermore, a soldering area can be more accurately determined by the irradiation of lattice patterns in different directions.

Furthermore, a shape is precisely measured three-dimensionally and an area is precisely assessed two-dimensionally and an area can be determined in three-dimensional and two-dimensional real time, so that reduce effects depending on the equipment, such as lighting, or a condition of a printed circuit board, and make it robust against noise.

Further, the saturation map and the variance map are created by the color images obtained by the color illuminations, and the soldering area is set by the saturation map and the variance map, thereby increasing the accuracy of the measurement of the soldering area. In addition, before the measurement of the soldering area, at least one method of correcting the color uniformity for the color illuminations and correcting the solder uniformity for the color illuminations is performed, thereby increasing the accuracy of the measurement of the soldering area.

The foregoing general description and the following detailed description, by way of example and explanation, serve to further explain the claimed invention.

list of figures

• 1 ist eine schematische Darstellung, in der eine Vorrichtung zur Messung einer dreidimensionalen Form dargestellt ist, die für ein Verfahren zur Messung einer dreidimensionalen Form gemäß einem Ausführungsbeispiel der vorliegenden Erfindung verwendet wird.
• 2 ist ein Flussdiagramm, in dem ein Verfahren zur Messung eines Lötbereichs gemäß einem Ausführungsbeispiel der vorliegenden Erfindung gezeigt ist.
• 3 ist eine Querschnittdarstellung, in der ein Abschnitt einer Leiterplatte dargestellt ist, auf dem ein Lot ausgebildet ist.
• 4 ist ein Flussdiagramm, in dem ein Ausführungsbeispiel eines Verfahrens zum Erhalt einer zweidimensionalen Farbinformation, das in dem Verfahren zur Messung des Lötbereichs in 2 enthalten ist, gezeigt ist.
• 5 ist ein Flussdiagramm, in dem ein Verfahren zur Messung eines Lötbereichs gemäß einem weiteren Ausführungsbeispiel der vorliegenden Erfindung gezeigt ist.
• 6 ist eine schematische Darstellung, in der eine Vorrichtung zur Messung einer dreidimensionalen Form dargestellt ist, die für ein Verfahren zur Messung einer dreidimensionalen Form gemäß einem weiteren Ausführungsbeispiel der vorliegenden Erfindung verwendet wird.
• 7 ist ein Flussdiagramm, in dem ein Verfahren zur Messung eines Lötbereichs gemäß noch einem weiteren Ausführungsbeispiel der vorliegenden Erfindung gezeigt ist.
• 8 zeigt ein rotes Bild, ein grünes Bild und ein blaues Bild entsprechend jeweils einer roten Beleuchtung, einer grünen Beleuchtung und einer blauen Beleuchtung.
• 9 ist ein Bild, das ein Beispiel einer Sättigungskarte zeigt.
• 10 ist ein Bild, das ein Beispiel einer Varianzkarte zeigt.
• 11 ist ein Bild, das ein Beispiel einer Lötkarte zeigt.
• 12 ist ein Flussdiagramm, in dem ein Verfahren zur Korrektur der Farbgleichmäßigkeit gemäß einem Ausführungsbeispiel der vorliegenden Erfindung gezeigt ist.
• 13 ist ein Bild, das eine rote Beleuchtung zeigt, die man durch die Verwendung eines grauen Ziels als Zielobjekt erhält.

The appended drawings, which are included for ease of understanding the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

• 1 FIG. 13 is a schematic diagram showing a three-dimensional shape measuring apparatus used for a three-dimensional shape measuring method according to an embodiment of the present invention. FIG.
• 2 FIG. 10 is a flowchart showing a method of measuring a soldering area according to an embodiment of the present invention. FIG.
• 3 is a cross-sectional view in which a portion of a printed circuit board is shown, on which a solder is formed.
• 4 FIG. 11 is a flow chart showing an embodiment of a method of obtaining two-dimensional color information used in the method of measuring the soldering area in FIG 2 is shown.
• 5 FIG. 10 is a flowchart showing a method of measuring a soldering portion according to another embodiment of the present invention. FIG.
• 6 FIG. 13 is a schematic diagram showing a three-dimensional shape measuring apparatus used for a three-dimensional shape measuring method according to another embodiment of the present invention. FIG.
• 7 FIG. 10 is a flowchart showing a method of measuring a soldering area according to still another embodiment of the present invention. FIG.
• 8th shows a red picture, a green picture and a blue picture, each corresponding to a red illumination, a green illumination and a blue illumination.
• 9 is an image showing an example of a saturation map.
• 10 is an image showing an example of a variance map.
• 11 is an image showing an example of a solder card.
• 12 FIG. 10 is a flowchart showing a color uniformity correction method according to an embodiment of the present invention. FIG.
• 13 is an image that shows a red illumination that is obtained by using a gray target as the target.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention will now be described in more detail with reference to the accompanying figures, in which embodiments of the present invention are shown. However, the present invention may be embodied in several ways and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are intended to aid the thoroughness and completeness of this disclosure and to those skilled in the art appreciate the scope of the present invention. The size and relative size of layers and regions may be exaggerated in the figures for the sake of clarity.

If an element or layer is referred to as being "on another element or layer or as being" connected to "or" coupled to "another element or layer, it may be directly on the other element or layer be, or be connected or coupled to it, or there may be intervening elements or layers. Conversely, if an element is considered to be "immediately upon" another element or layer, or "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. Like reference numerals refer to like elements throughout. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Although the terms "first," "second," "third," etc. are used herein to describe various elements, components, regions, layers, and / or sections, they are intended to be used herein to describe Elements, components, regions, layers, and / or sections should not be limited to these terms. These terms are only for the purpose of distinguishing one element, component, region, layer or section from another region, layer or other section. A first element, a first component, a first region, a first layer or a first section, which is referred to below, could therefore also be referred to as a second element, second component, second region, second layer or second section, without to depart from the teachings of the present invention.

Spatial terms such as "below," "below," "lower," "above," "upper," and the like may be used herein to more readily describe a ratio of one element or feature to another element / other elements or another feature / feature as shown in the figures. Terms related to space are intended to include, in addition to the orientation shown in the figures, different orientations of the device in use or in operation. For example, if the device is upside down in the figures, elements described as being "below" or "below" other elements or features would be aligned "above" the other elements or features. The example term "below" can therefore encompass both an "over" and "under" orientation. The device may be otherwise oriented (rotated 90 ° or otherwise rotated) and the spatial description used herein may be construed accordingly.

The technical vocabulary used here is only for the description of certain embodiments and is not intended to limit the present invention. The singular forms "a / e" and "the" used below are also intended to include the plural, unless clearly dictated by the context. If the terms "comprising" or "having" are used in this patent specification, they are used to denote the presence of the specified features, integers, steps, operations, elements and / or components, although it is not excluded that there is still one or several other features, integers, steps, operations, elements, components, and / or groups thereof.

Embodiments of the invention will now be described with reference to cross-sectional views which are schematic illustrations of idealized embodiments (and intervening structures) of the present invention. It is therefore to be expected, for example, by the manufacturing technology and / or tolerances, deviations from the shapes of the representations. Embodiments of the present invention should therefore not be construed as limiting to particular forms or regions illustrated herein, but may, for example, be subject to variations in shape as a result of manufacturing. For example, an implanted region depicted as a rectangle typically has rounded or curved features and / or an increase in the concentration of the implant at its edges rather than a binary change from an implanted to an unimplanted region. Likewise, in an implanted implanted region, implantation may occur in the region between the embedded region and the surface through which implantation occurs. The regions shown in the figures are therefore schematic and their shapes are not intended to represent the actual shape of a region or device and are not intended to limit the scope of the present invention.

All terms (including technical and scientific terms) used herein, unless otherwise defined, mean the meaning of a person skilled in the art to which this invention belongs. The meaning of terms defined in common dictionaries should be construed as meaningful in the context of the relevant art and not idealized or overly formalized unless expressly so defined herein.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 FIG. 13 is a schematic diagram showing a three-dimensional shape measuring apparatus used for a three-dimensional shape measuring method according to an embodiment of the present invention. FIG.

According to 1 For example, a three-dimensional shape measuring apparatus used for measuring a three-dimensional shape according to an embodiment of the present invention may include a measuring stage portion 100 an image photographing section 200 a first illumination unit comprising a first and second illumination section 300 and 400 has a second illumination unit 450 , an image holding section 500 , a module control section 600 and a central control section 700 exhibit.

The measuring stage section 100 can be a level 110 that is a measurement target 10 carries, and a stage transfer unit 120 that the stage 110 transmits, exhibit. In one embodiment, a measurement location may be in the measurement target 10 according to a movement of the measurement target 10 with respect to the image photographing section 200 and the first and second illumination sections 300 and 400 through the stage 110 to be changed.

The picture photographing section 200 is above the level 110 arranged so that he from the measurement target 10 receives reflected light and an image of the measurement target 10 measures. The picture photographing section 200 thus receives the light coming from the first and second illumination section 300 and 400 exit and from the measurement target 10 is reflected, and photographs a plan image of the measurement target 10 ,

The picture photographing section 200 can a camera 210 , an imaging lens 220 , a filter 230 and a lamp 240 exhibit. The camera 210 gets that from the measurement target 10 reflected light and photographed the plan image of the measurement target 10 , The camera 210 For example, it may include a CCD camera or a CMOS camera. The imaging lens 220 is under the camera 210 arranged so that they are the target of the measurement 10 reflected light on the camera 210 maps. The filter 230 is under the imaging lens 220 arranged so he gets that from the measurement target 10 reflected light filters and the imaging lens 220 supplied with the filtered light. The filter 230 For example, it may have a frequency filter, a color filter, or a light intensity control filter. The lamp 240 can be circular under the filter 230 be arranged so that they are the measurement target 10 supplied with light, giving a specific image, such as a two-dimensional shape of the measurement target 10 , photographed.

The first lighting section 300 may, for example, on a right side of the image photographing section 200 be arranged so that he respect the stage 110 that the measurement target 10 wears, is oblique. The first lighting section 300 may be a first light source unit 310 , a first grid unit 320 , a first grating transfer unit 330 and a first condenser lens 340 exhibit. The first light source unit 310 may comprise a light source and at least one lens for generating light, wherein the first grid unit 320 under the first light source unit 310 is arranged so that it from the first light source unit 310 generated light in a first grid pattern light having a grid pattern converts. The first grating transfer unit 330 is with the first grid unit 320 connected, making them the first lattice unit 320 transmits, and may for example comprise a piezoelectric transmission unit or a precise linear transmission unit. The first condenser lens 340 is under the first grid unit 320 arranged so that they are the first grid pattern light coming out of the first grid unit 320 exit, on the measurement target 10 collects.

The second lighting section 400 For example, on a left side of the image photographing section 200 be arranged so that he respect the stage 110 that the measurement target 10 wears, bevels. The second lighting section 400 may be a second light source unit 410 , a second lattice unit 420 , a second grating transfer unit 430 and a second condenser lens 440 exhibit. The second lighting section 400 substantially corresponds to the first illumination section described above 300 , whereby more detailed explanations can be omitted.

When the first grating transfer unit 330 the first grid unit 320 successively moved N times and in the first illumination section 300 N first grid pattern lights on the measurement target 10 can be irradiated, the image photographing section 200 successively the N first grid pattern lights that are from the first measurement target 10 be reflected and photographed N first pattern images. When the second grating transfer unit 430 the second grid unit 420 successively moved N times and in the second illumination section 400 N first grid pattern lights on the measurement target 10 In addition, the Bildfotografierabschnitt 200 successively the N second grating pattern lights coming from the first measurement target 10 be reflected and photograph N second sample images. "N" is a natural number and can be 4, for example.

In one embodiment, the first and second illumination sections become 300 and 400 as a lighting device that generates first and second grating pattern lights. Alternatively, there may be more than three or three lighting sections. In other words, the grating pattern light may be directed to the measurement target in different directions 10 are irradiated and it can be photographed various pattern images. For example, when three illumination sections are arranged in an equilateral triangular shape, the image photographing section 200 is the center of the equilateral triangular shape, so can three grid pattern lights in different directions on the measurement target 10 be irradiated. For example, if four lighting sections are arranged in a square shape, the image photographing section 200 the center of the square shape forms, four grid pattern lights in different directions can point to the measurement target 10 be irradiated. The first illumination unit may also have eight illumination sections, and grid pattern lights may be in eight directions to the measurement target 10 be beamed so that a picture is photographed.

The second lighting unit 450 emits light to obtain a two-dimensional image of the measurement target 10 to the measurement target 10 one. In one embodiment, the second lighting unit 450 a red lighting 452 , a green lighting 454 and a blue lighting 456 exhibit. The red lighting 452 , the green lighting 454 and the blue lighting 456 can be circular over the measurement target 10 be arranged so that each red light, green light and blue light is irradiated, taking, as in 1 shown, can be arranged at different heights.

The picture holding section 500 is with the camera 210 of the picture photograph section 200 electrically connected so that the pattern images corresponding to the first illumination unit of the camera 210 and the resulting pattern images are saved. Furthermore, the picture holding section obtains 500 the two-dimensional images corresponding to the second illumination unit of the camera 210 and stores the obtained two-dimensional images. The picture holding section 500 For example, it may have an image system similar to that in the camera 210 photographed N first pattern images and N second pattern images and stores the images.

The module control section 600 is for controlling the measuring stage section 100 , the image photographing section 200 , the first lighting section 300 and the second illumination section 400 with the measuring stage section 100 , the image photographing section 200 , the first lighting section 300 and the second illumination section 400 electrically connected. The module control section 600 For example, it may include a lighting control device, a grid control device, and a step control device. The lighting control device controls the first and second light source units 310 and 410 such that they generate light, and the grid control device controls the first and second grid transfer units 330 and 430 such that they are the first and second lattice unit 320 and 420 move. The stage control device controls the stage transfer unit 120 such that they are the stage 110 moved up and down and left and right.

The central control section 700 is for controlling the image holding section 500 and the module control section 600 with the picture holding section 500 and the module control section 600 electrically connected. In particular, the central control section receives 700 the N first pattern images and the N second pattern images from the image holding system of the image holding section 500 to process the images so that a three-dimensional shape of the measurement target can be measured. Furthermore, the central control section 700 a lighting control device, a grid control device, and a stage control device of the module control section 600 exhibit. The central control section may thus comprise an image processing panel, a control panel and an interface panel.

The following is a method for measuring the measuring target formed on a printed circuit board 10 be described in detail by means of the above-described apparatus for measuring a three-dimensional shape, by using a solder as an example of the measurement target 10 is used.

2 FIG. 10 is a flowchart showing a method of measuring a soldering area according to an embodiment of the present invention. FIG. 3 is a cross-sectional view in which a portion of a printed circuit board is shown, on which a solder is formed.

According to 1 to 3 For measuring a soldering area, first of all a three-dimensional height information of the printed circuit board is obtained 900 by means of a first image which is photographed, while grating pattern light is applied to the printed circuit board by means of a first illumination unit 900 is irradiated (see step S110). For example, the grating pattern light may be irradiated in at least two directions.

The three-dimensional height information can be obtained by executing a bucket algorithm with respect to the first image obtained by irradiating grating pattern lights corresponding to the N successive movement of the first and second grating units 320 and 420 receives.

Then, a first area AR1, which is at a height greater than or equal to a reference height H1, on a base plate 910 the circuit board 900 protrudes, determined by means of the obtained height information as a soldering area (see step S120).

If an area corresponding to a height greater than a predetermined or equal to a predetermined minimum elevation wave may generally be regarded as a soldering area, then the reference altitude H1 may be set as the predetermined minimum altitude threshold.

Thereafter, a color information of the printed circuit board is obtained 900 by means of a second image that is photographed while a light is coming from a second illumination unit 450 is generated on the circuit board 900 is irradiated (see step S130).

The second lighting unit 450 generates light to obtain a two-dimensional image of the measurement target 10 , In one embodiment, the second lighting unit 450 a red lighting 452 , a green lighting 454 and a blue lighting 456 each generating red light, green light and blue light. The second image can be obtained by using not only a color camera but also a black and white camera. In the 1 shown camera 210 can thus have a black and white camera. In a further embodiment, the second lighting unit 250 have a lighting unit with monochromatic light. The second image can be obtained by means of a color camera, whereby the in 1 shown camera 210 a color camera may have.

The color information may, for example, comprise RGB information (red, green and blue) or CMY information (C = cyan, M = magenta, Y = yellow). The first color information may also have color information corresponding to another color combination. The first color information can be obtained by a pixel unit of the first area AR1.

• 4 ist ein Flussdiagramm, in dem ein Ausführungsbeispiel eines Verfahrens zum Erhalt einer zweidimensionalen Farbinformation, das in dem Verfahren zur Messung des Lötbereichs in 2 enthalten ist, gezeigt ist.

In this case, the color information of the circuit board can be 900 obtained as follows:

• 4 FIG. 11 is a flow chart showing an embodiment of a method of obtaining two-dimensional color information used in the method of measuring the soldering area in FIG 2 is shown.

According to 4 is used to obtain the color information of the PCB 900 first that of the second lighting unit 450 generated light on the circuit board 900 is irradiated so that the second image is photographed (refer to step S132).

Then, the RGB information or the CMY information is extracted from the photographed second image (refer to step S133). In one embodiment, upon receipt of the photographed second image by the in 1 shown picture holding section 500 the RGB information or the CMY information by means of the in 1 extracted image processing disk are extracted.

Thereafter, the extracted RGB information or CMY information is filtered to obtain the filtered RGB information or CMY information (see step S134). In one embodiment, data other than a mean value in the image processing disk is excluded from the extracted RGB information or CMY information based on a selected criterion, and the remaining data other than the dissimilar data is finally determined as RGB information or as CMY information.

According to 1 to 3 is then a first color information of the first area AR1, based on the obtained color information of the circuit board 900 is determined as the soldering area, set as the reference color information (refer to step S140).

Thereafter, the reference color information and a color information of a region from which the first region AR1 is excluded are compared to judge whether or not the solder is formed in the region from which the first region AR1 is excluded (refer to step S150 ).

In order to obtain a region having color information substantially corresponding to the reference color information, the color information of other regions may be used.

5 FIG. 10 is a flowchart showing a method of measuring a soldering portion according to another embodiment of the present invention. FIG.

According to 3 and 5 after setting the first color information of the first area AR1 as reference color information in step S140, second color information of a second area AR2 in which a predetermined excellent comparison object is obtained is obtained 920 is arranged, based on the measured color information of the circuit board 900 (see step S142). The comparison object 920 may correspond to a contact point of the circuit board.

Since the second color information of the second area AR2 can be obtained from the color information, the second color information can be in substantially the same form as the first color information. The second color information may include RGB information or CMY information. The second color information may also have color information corresponding to another color combination.

Thereafter, third color information of a third area AR3 in which no measurement target is formed is obtained from the measured color information of the printed circuit board 900 (see step S144). The third area AR3 corresponds to a surface area having no height.

Since the third color information of the third area AR3 can be obtained from the color information, the third color information can have substantially the same shape as the first color information and the second color information. For example, the third color information may include RGB information or CMY information. The third color information may also have color information corresponding to another color combination.

Then, the first, second and third color information of the first, second and third areas AR1, AR2 and AR3 are divided into first, second and third clusters (refer to step S146).

The first, second and third color information indicate the color information of each area, the color information having a characteristic tendency for each area. The first, second and third color information can thus form a specific cluster for each area.

The cluster may have a feature extracted from the obtained color information by means of a color coordinate system. The first, second and third clusters may, for example, have hue and / or color saturation and / or light intensity (HSI), which are converted by the RGB information or the CMY information. The method for converting the RGB information or the CMY information into the HSI information can be carried out by known methods, so that further explanations can be omitted.

A cluster algorithm may be applied to the first, second and third regions AR1, AR2 and AR3 with at least one piece of information of each HSI information of the regions, such that the first, second and third regions AR1, AR2 and AR3 are respectively in the first, second and subdivide third clusters.

As described above, after dividing the first, second and third areas AR1, AR2 and AR3 into the clusters according to the color information in the comparison of the reference color information and the color information of the area from which the first area AR1 is excluded, it is judged whether the Lot in the area from which the first area AR1 is excluded (refer to step S150) checks for color information of a predetermined portion of the circuit board 900 from which the first, second and third areas AR1, AR2 and AR3 are excluded belongs to the first cluster or not, and if the color information belongs to the first cluster, it can be judged that the solder is formed on the predetermined portion.

If a predetermined section on the base plate 910 belonging to the first, second and third areas AR1, AR2 and AR3 corresponding to a range AR4 of a lot below the reference level H1 (hereinafter referred to as "fourth area"), the fourth area AR4 belongs to a group belonging to the group of the first area AR1 divided into the first cluster according to the first color information, since color information of the fourth area AR4 is similar to the first color information of the first area AR1. That is, the fourth area AR4 can be divided into the first cluster which is equal to the first area AR1.

Accordingly, as compared with a method for judging an area corresponding only to a height greater than or equal to a predetermined reference height as a soldering area, an area corresponding to a height smaller than the predetermined reference altitude may be Soldering area also be included in the soldering area, so that the soldering area can be determined correctly.

Although in 5 For an example of splitting ranges into three clusters, the number of clusters can be two or more than four or four.

• Zuerst erhält man eine Farbinformation eines als Lötbereich vorbestimmten Bereichs, von dem der erste Bereichs AR1 ausgenommen ist, um die Referenzfarbinformation des ersten Bereichs AR1 und die Farbinformation des vorbestimmten Bereichs jeweils in einen ersten und zweiten Cluster zu unterteilen. Dann wird beim Vergleich der Referenzfarbinformation und der Farbinformation des Bereichs, von dem der erste Bereich AR1 ausgenommen ist, zur Beurteilung, ob das Lot in dem Bereich, von dem der erste Bereich AR1 ausgenommen ist, ausgebildet ist oder nicht (vgl. Schritt S150), überprüft, ob der zweite Cluster dem ersten Cluster angehört oder nicht, wobei, falls der zweite Cluster dem ersten Cluster angehört, beurteilt werden kann, dass der dem zweiten Cluster entsprechende Bereich dem Lötbereich angehört.

For example, if the number of clusters is four, the soldering range can be determined as follows:

• First, a color information of a predetermined range as the soldering area, of which the first area AR1 is excluded, is obtained to divide the reference color information of the first area AR1 and the color information of the predetermined area into first and second clusters, respectively. Then, in comparing the reference color information and the color information of the area from which the first area AR1 is excluded, to judge whether or not the solder is formed in the area from which the first area AR1 is excluded (refer to step S150). , checks if the second cluster belongs to the first cluster or not, and if the second cluster belongs to the first cluster, it can be judged that the area corresponding to the second cluster belongs to the soldering area.

Upon receipt of the color information of the printed circuit board 900 In step S130, visibility information may additionally be used. The visibility represents a ratio of the amplitude B _i (x, y) to the mean value A _i (x, y) in luminance signals of an image, and has an approximate tendency to increase as the reflectance increases. Visibility V _i (x, y) is defined as follows: $${\text{V}}_{\text{i}}\left(\text{x}\text{, y}\right)={\text{B}}_{\text{i}}\left(\text{x}\text{, y}\right)/{\text{A}}_{\text{i}}\left(\text{x}\text{, y}\right)$$

The grid pattern light will be applied to the circuit board in different directions 900 so that different types of pattern images are photographed. As in 1 ₂ , the image holding section 500 extracts N brightness levels I ⁱ ₁ , I ⁱ ₂ ,..., I ⁱ _N in each position i (x, y) in an XY coordinate system of N in the camera 210 photographed pattern images and produces an average brightness A _i (x, y) and visibility V _i (x, y) by means of an N-bucket algorithm.

$$V_i\left(x,y\right)=\frac{B_i}{A_i}=\frac{\sqrt{{\left(2I_1^i-I_2^i-I_3^i\right)}^2+3{\left(I_2^i-I_3^i\right)}^2}}{\left(I_1^i+I_2^i+I_3^i\right)}$$

For example, if N = 3 and N = 4, visibility can be made as follows: $$A_i\left(x.y\right)=\frac{I_1^i+I_2^i+I_3^i}{3}$$

$$V_i\left(x.y\right)=\frac{B_i}{A_i}=\frac{\sqrt{{\left(2I_1^i-I_2^i-I_3^i\right)}^2+3{\left(I_2^i-I_3^i\right)}^2}}{\left(I_1^i+I_2^i+I_3^i\right)}$$

$$V_i\left(x,y\right)=\frac{B_i}{A_i}=\frac{2\sqrt{{\left(I_1^i-I_3^i\right)}^2+{\left(I_2^i-I_4^i\right)}^2}}{\left(I_1^i+I_2^i+I_3^i+I_4^i\right)}$$

If N = 4, the visibility is made as follows: $$A_i\left(x.y\right)=\frac{I_1^i+I_2^i+I_3^i+I_4^i}{4}$$

$$V_i\left(x.y\right)=\frac{B_i}{A_i}=\frac{2\sqrt{{\left(I_1^i-I_3^i\right)}^2+{\left(I_2^i-I_4^i\right)}^2}}{\left(I_1^i+I_2^i+I_3^i+I_4^i\right)}$$

The color information such as the first, second and third color information described above has a characteristic tendency for each area, and also the visibility information prepared as described above has a characteristic tendency for each area. Therefore, in addition to the color information, the visibility information for measuring the soldering area can optionally be used. Also, only the visibility information without color information can be used to measure the soldering area.

Specifically, the visibility information can be obtained on the basis of N grating pattern lights according to the movement of the grating unit, and then the visibility information for the first area and the visibility information for the area from which the first area is excluded are compared with each other to judge whether the measurement target is formed in the region from which the first region is excluded or not.

The visibility information of the circuit board can be determined by means of the in 2 received first image. For since the first image has all the information for obtaining the visibility information described above, the visibility information can be obtained from the first image.

As in 5 described, the first, second and third regions AR1, AR2 and AR3 can be divided into the first, second and third clusters by means of the obtained visibility information, whereby it can be judged whether a predetermined portion of the base plate 910 of which the first, second and third areas AR1, AR2 and AR3 are excluded, belongs to the first cluster or not.

After determining the soldering area in the manner described above, the predetermined soldering area can be used in various methods. For example, the quantity of the area to be soldered is produced, and it can be judged by means of the manufactured quantity whether the circuit board on which the solder is formed is good or bad.

As described above, an area corresponding to a height greater than or equal to a predetermined reference height H1 is determined as a soldering area, and color information of the soldering area is set as reference color information, so that the color information of the soldering area coincides with another area is compared. An area corresponding to a height below the reference height H1, which may be omitted, is therefore part of the soldering area, whereby the soldering area can be measured accurately.

In addition, although the solder is spread thinly on the base plate, which is common in the formation of a solder, the soldering area can be accurately measured.

When the color information of the first area AR1, a soldering area corresponding to a height greater than or equal to a predetermined reference height H1 and the color information of the second and third areas AR1 and AR2 is obtained and packaged in clusters, it is possible In addition, a section whose integration into the soldering area is unclear, more clearly assess.

Furthermore, a soldering area can be more accurately determined by means of visibility information.

Furthermore, a soldering area can be more accurately determined by the irradiation of grid pattern lights in different directions.

Further, a shape is precisely measured three-dimensionally and an area is precisely two-dimensionally evaluated and an area can be determined three-dimensionally and two-dimensionally in real time, so that effects depending on the equipment such as illumination or a condition of a circuit board decrease and robustness with respect to Noise can be achieved.

6 FIG. 13 is a schematic diagram showing a three-dimensional shape measuring apparatus used for a three-dimensional shape measuring method according to another embodiment of the present invention. FIG.

According to 6 can a device 1100 For measuring a three-dimensional shape used for a method of measuring a three-dimensional shape according to another embodiment of the present invention, a step 1120 an image photographing section 1130 , a first lighting unit 1140 , a second lighting unit 1150 and a control section 1160 exhibit.

The stage 1120 carries a measurement target 1110 such as a circuit board, and moves in accordance with a control of the control section 1160 , so the measurement target 1110 to a place of measurement. A measurement location in the measurement target 1110 can according to a movement of the measurement target 1110 with respect to the image photographing section 1130 and the first lighting section 1140 through the stage 1120 to be changed.

The picture photographing section 1130 is above the level 1120 arranged and obtained from the measurement target 1110 reflected light, giving an image of the measurement target 1110 is photographed. The picture photographing section 1130 is, for example, in one direction over the step 1110 arranged substantially perpendicular to a reference surface of the step 1120 is.

The picture photographing section 1130 For example, a camera and an imaging lens may be used to photograph the image of the measurement target 1110 exhibit. The camera gets that from the measurement target 1110 reflected light, so that the image of the measurement target 1110 is photographed, and may for example comprise a CCD camera or a CMOS camera. The imaging lens is located under the camera, so that of the measurement target 1110 reflected light is imaged on the camera.

The picture photographing section 1130 gets from the measurement target 1110 reflected light onto which a pattern illumination falls, from a first illumination unit 1140 is irradiated, and photograph a pattern image of the measurement target 1110 , In addition, the image photographing section receives 1130 from the measurement target 1110 reflected light onto which a color illumination falls, that of a second illumination unit 1150 is irradiated, and photographed a color image of the measurement target 1110 ,

The first lighting unit 1140 is so above the level 1120 arranged that they respect the stage 1120 is oblique at a predetermined angle. The first lighting unit 1140 is used to measure a three-dimensional shape of the measurement target 1110 and generates pattern illumination to illuminate the measurement target 1110 , The first lighting unit 1140 For example, the pattern illumination irradiates at an inclination of about 30 degrees with respect to a normal line of the reference surface of the step 1120 one.

To increase the accuracy of measurement, several first lighting units 1140 present that radiate the pattern illumination in different directions. A variety of first lighting units 1140 may be along a circumferential direction at substantially the same angle from the center of the image photographing section 1130 can be arranged from considered. The device 1100 For example, six first lighting units can be used to measure a three-dimensional shape 1140 which are spaced about 60 degrees apart. Alternatively, the device 1100 for measuring a three-dimensional shape first lighting units 1140 different numbers, such as 2, 3, 4, 8, etc. have. The first lighting units 1140 The pattern illumination in substantially the same time interval radiates in different directions with respect to the measurement target 1110 one.

Every first lighting unit 1140 can be a light source 1142 and a grid element 1144 for generating the pattern illumination. The of the light source 1142 generated lighting is converted into the pattern lighting while passing through the grid element 1144 occurs. The grid element 1144 Moves n times by 2π / n by means of a grating transfer unit, such as a piezoelectric actuator (PZT actuator), so that the pattern illumination, in which the phase transition has occurred, is generated. "N" is a natural number greater than or equal to 2. The first lighting unit 1140 emits the pattern illumination for each movement to the measurement target 1110 while holding the grid element 1144 moved n times. The first lighting unit 1140 may further comprise a projection lens (not shown) for focusing the grating element 1144 trained pattern illumination and for projecting the focused pattern illumination on the measurement target 1110 exhibit.

The second lighting unit 1150 serves to obtain a two-dimensional image of the measurement target 1110 and creates the color illumination and radiates it to the measurement target 1110 one. The second lighting unit 1150 may have a plurality of color lighting parts for producing different color illuminations. The second lighting unit 1150 can, for example, a red lighting part 1152 creating a red lighting, a green lighting part 1154 who has a green lighting generated, and a blue lighting part 1156 which produces a blue illumination. The red lighting part 1152 , the green lighting part 1154 and the blue lighting part 1156 are circular above the measurement target 1110 arranged so that each of the red lighting, the green lighting and the blue lighting on the measurement target 1110 be irradiated.

The control section 1160 controls the elements described above completely. In particular, the control section controls 1160 the movement of the stage 1120 such that the measurement target 1110 is placed at the measurement location. The control section 1160 operates the first lighting units in succession 1140 , The control section 1160 moves the grid element 1144 every first lighting unit 1140 gradually and controls the first lighting unit 1140 such that the color lighting for each movement towards the measurement target 1110 is irradiated. The control section 1160 controls the second lighting unit 1150 such that the color illumination is at the measurement target 1110 is irradiated, so that you get a two-dimensional image of the measurement target 1110 receives. The control section 1160 controls the image photographing section 1130 such that it displays the pattern image by means of the pattern illumination provided by the first illumination unit 1140 radiated and the measurement target 1110 is reflected, photographed and that he took the color image, by means of the pattern illumination, by the second lighting unit 1150 radiated and the measurement target 1110 is reflected, photographed. Furthermore, the control section measures 1160 by the pattern image and the color image included in the image photographing section 1130 were photographed, the three-dimensional shape of the measurement target 1110 ,

Hereinafter, a method for measuring a soldering area on a printed circuit board by means of the apparatus for measuring a three-dimensional shape will be described.

7 FIG. 10 is a flowchart showing a method of measuring a soldering area according to still another embodiment of the present invention. FIG.

According to 6 and 7 is used to measure a soldering area on a circuit board 1110 First, a variety of color lighting on the circuit board 1110 is irradiated to obtain a plurality of color images (refer to step S1100). After successively irradiation of the color illuminations on the circuit board 1110 by means of the second illumination unit 1150 Thus, one obtains the color image corresponding to each color illumination by means of the image photographing section 1130 , After the illumination of red lighting, green lighting and blue lighting on the circuit board 1100 by means of the red lighting part 1152 , the green lighting part 1154 and the blue lighting part 1156 that in the second lighting unit 1150 For example, according to each color illumination, a red image, a green image, and a blue image are obtained.

8th shows a red picture, a green picture and a blue picture, each corresponding to a red illumination, a green illumination and a blue illumination.

Out 8th it becomes apparent that distributions of a red image 1210 , a green picture 1220 and a blue picture 1230 within a field of view because the chromatic aberration has different wavelengths according to the use of the red illumination, the green illumination, and the blue illumination.

Then, the HSI information for each color containing hue, chroma and light intensity is obtained by the color coordinate conversion of the obtained color images. The method for converting an RGB information into the HSI information can be carried out by means of known methods, so that further explanations can be omitted.

Prior to the color coordinate conversion of the obtained color images, the color saturation can be facilitated by applying a mean value filter to the obtained color images.

Thereafter, saturation information for each color of the HSI information becomes a saturation map 1300 created (see step S1110). An example of the created saturation card 1300 is in 9 shown.

The saturation card 1300 can by means of the saturation information for each pixel with respect to the red image 1210 , the green picture 1220 and the blue picture 1230 to be created. In particular, the saturation card 1300 on the basis of the color saturation for each pixel obtained by the following equation 1. $$\text{saturation}=(11-3\cdot \text{min}\left(\text{R}\text{,G}\text{, B}\right)/\left(\text{R}+\text{G}+\text{B}\right)$$

According to Equation 1, R 'corresponds to saturation information for each pixel in the red image 1210 , G 'is a saturation information for each pixel in the green image 1220 , and 'B' a saturation information for each pixel in the blue image 1230 ,

The saturation map created from Equation 1 has a range of about 0 to about 1 and represents a base color when the saturation map 1300 the value 1 approaches. Because the lot 1310 typically approaching an achromatic color, an area that is on the saturation map 1300 has a value close to 0, can be essentially judged as a soldering area.

But next to the lot 1310 also a wiring pattern 1320 , a dark soldermask 1330 , etc. of an achromatic color may be a range of the wiring pattern 1320 , an area of the dark solder mask 1330 , etc. in the saturation card 1300 be confused with the soldering area.

Therefore, after the creation of the saturation card 1300 an unnecessary area, such as the wiring pattern 1320 , the dark soldermask 1330 , etc. from the saturation card 1300 be excluded.

The area of the wiring pattern 1320 and / or the area of the solder resist 1330 Thus, by means of the light intensity information for each color, the HSI information is removed from the saturation map 1300 excluded, so that a first soldering area is set (refer to step S1120).

The first soldering area can be determined by the light intensity information based on the HSI information obtained by the color coordinate conversion of the color images. Especially with regard to the color saturation, the solder can 1310 , the wiring pattern 1320 and the dark soldermask 1330 only slightly different from each other while the difference in light intensity is large. Namely, since the reflectivity of the metal wiring pattern 1320 compared to the lot 1310 is high, it is determined that the light intensity of the wiring pattern 1320 bigger than the lot 1310 is, and there the reflexivity of the dark solder mask 1330 compared to the lot 1310 is low, it is determined that the light intensity of the dark solder resist 1330 significantly lower than that of the lot 1310 is. Therefore, an area in which the light intensity compared to the lot 1310 is large or small, due to the difference in light intensity can be removed, so that the superfluous area, such as the wiring pattern 1320 , the dark soldermask 1330 , etc. from the saturation card 1300 can be removed.

Then, a saturation average value is created for each color in the first soldering region (refer to step S1130). That is, based on the designated first soldering area, the saturation average value for each color becomes the red image, respectively 1210 , the green picture 1220 and the blue picture 1230 , in the 8th are shown produced. Since the produced saturation value for each color corresponds to the saturation value for the first soldering area in which, after the judgment, the solder 1310 is substantially formed, the produced saturation value can be used as a criterion for the color saturation of the solder 1310 consider.

Thereafter, by means of the saturation information for each color and the saturation average for each color, a variance map 1400 created (see step S1140). An example of the created variance map 1400 is in 10 shown.

The variance map 1400 can be determined by the saturation information for each pixel of the red image 1210 , the green picture 1220 and the blue picture 1230 and the saturation average for each color of the red image 1210 , the green picture 1220 and the blue picture 1230 create. In particular, the variance map can be 1400 on the basis of a variance value for each pixel represented by the following Equation 2: $$\text{variance}=\text{Section}\left(\text{R-RA}\right)+\text{Section}\left(\text{G GA}\right)+\text{Section}\left(\text{B-BA}\right)$$

According to Equation 2, R 'corresponds to a saturation information for each pixel in the red image 1210 , G 'is a saturation information for each pixel in the green image 1220 , and 'B' is a saturation information for each Pixel in the blue picture 1230 , Furthermore, RA 'corresponds to a saturation average value for the first soldering area in the red image 1210 , 'GA' a saturation value for the first soldering area in the green image 1220 and, BA 'a saturation average value for the first soldering area in the blue image 1230 ,

According to Equation 2, as the difference between the color saturation and the saturation value of the color image for each pixel becomes larger, the variance value of the associated pixel is determined to be larger, and when a difference between the color saturation and the saturation average value of the color image is obtained for each pixel becomes smaller, it is determined that the variance value of the associated pixel is smaller. That is, if the variance value for each pixel is smaller, then the eventuality that the associated pixel corresponds to the lot increases and, conversely, the eventuality that the associated pixel corresponds to the lot decreases when the variance value for each pixel is larger.

After that, the variance values for pixels on the variance map 1400 compared to each other to get a solder card 1500 on which the second soldering area is illustrated, in which the solder is substantially formed (see step S1150). An example of the created solder card 1500 is in 11 shown.

A method for determining the second soldering area may include setting an arbitrary critical value as a variance value by a user, judging that the corresponding pixel does not correspond to the soldering area when the variance value for the corresponding pixel exceeds the critical value, and judging that the corresponding pixels corresponds to the soldering area, if the variance value for the associated pixel does not exceed the critical value. In this case, an Otsu algorithm using a statistical method can be used as a variance value to set the critical value. The algorithm of Otsu corresponds to a method which has the setting of a cost function and considering a value indicating the minimum value of the cost function as a critical value in the determination of the critical value. If a gray value in an image is divided into two classes, the critical value corresponds to a discrete level value in the histogram due to the representation of the gray value distribution in the image in a histogram, and a section below the level value can be added to the class 1 and an area above the level value in the class 2 organize. Thus class can 1 can be judged as a soldering area and can be class 2 are judged to be an area not associated with the soldering area, so that the second soldering area is set in this way.

As described above, the second soldering area becomes the comparison on the variance map 1400 Thus, areas excluding the soldering area, such as a pattern area, can be effectively removed, so that the soldering area may possibly be specified accurately. In the formation of the solder card 1500 For example, the solder card can be formed more accurately by a method of removing a small spot, a limit weighting method, and so on.

Because the second lighting unit 1150 arranged to irradiate the color illumination in a circle over the printed circuit board, it may be that the light intensity for each area on the image in the photographing section 1130 photographed color image is detected unevenly. The color uniformity is corrected for each color illumination to reduce the unevenness of the light intensity for each area, so that the reliability for the measurement of the soldering area can be increased.

The color uniformity is corrected for the color illuminations prior to obtaining the color images in 8th and, by calibrating a gray target, compensation information for each color for correcting the color uniformity is prepared, and the light intensity information for each color can be corrected by the compensation information for each color.

12 FIG. 10 is a flowchart showing a color uniformity correction method according to an embodiment of the present invention. FIG. 13 is an image that shows a red illumination that is obtained by using a gray target as the target.

According to 6 . 12 and 13 At first, for correcting the color uniformity, the color illuminations are irradiated on a gray target so as to obtain a plurality of illuminating images for each color (refer to step S1200). After the successive irradiation of the color illuminations on the gray target by means of the second illumination unit 1150 Thus, one obtains the illumination images for colors corresponding to the color illuminations by means of the image photographing section 1130 , After irradiating the red lighting, the green lighting and the blue lighting on the gray target by means of the red lighting part 1152 , the green lighting part 1154 and the blue lighting part 1156 , the in the second lighting unit 1150 For example, a red illumination image, a green illumination image, and a blue illumination image corresponding to each color illumination are obtained.

This is how it works, for example 13 in which the obtained red illumination image is shown, it can be seen that the light intensity varies at locations within the field of view.

Then, the light intensity for each pixel with respect to the illumination image for each color is obtained (refer to step S1210). That is, one obtains and stores the light intensity information for each pixel based on the red illumination image, the green illumination image, and the blue illumination image.

Thereafter, a compensation ratio for each color is set according to a ratio between the light intensity for each pixel and an arbitrary reference light intensity for each pixel (refer to step S1220). The reference light intensity can be set as the average light intensity of the illumination image for each color. For example, an average light intensity of all the pixels within the field of view of the illumination image for each color is set as the reference light intensity. Alternatively, the reference light intensity may be set as a user-desired arbitrary value. The compensation ratio for each color with respect to each pixel can be expressed in Equation 3, for example. $$\begin{array}{l}\text{compensation ratio}=(\text{mean light intensity of the lighting}\\ \text{picture for each}\text{colour})/\left(\text{Light intensity of the associated pixel}\right)\end{array}$$

Then, the compensation ratios for each color of all the pixels within the field of view are database-enhanced, so that the compensation information for each color is created and stored (refer to step S1230). The stored compensation information for each color may be used to increase the accuracy of the measurement of the solder area that will be processed later. For example, after the irradiation of the color illuminations on the circuit board to obtain the color images and before the saturation map is formed by the color images, each pixel of the color images is compensated by the compensation ratio for each color. That is, each pixel of the color images is multiplied by the compensation ratio for each color, so that the unevenness of the light intensity of the color illumination itself is compensated and a mistake in the measurement of the soldering area is reduced.

In accordance with the properties of a solder ball contained in the solder, a deviation of the light intensity for each color in the soldering area may occur. To reduce the deviation of the light intensity for each color of the solder, the solder uniformity for the color illuminations can be corrected, so that the reliability of the measurement of the soldering area can be increased.

Correction of the solder uniformity for the color illuminations may be made prior to receipt of the inks 8th shown color images done. In particular, the color illuminations are radiated onto the solder formed on the printed circuit board, so that soldering images are obtained for each color. For example, after the red illumination, the green illumination and the blue illumination are irradiated, the solder formed on the circuit board is obtained by means of the red illumination part 1152 , the green lighting part 1154 and the blue illumination part 1156 that in the second lighting unit 1150 a red solder image, a green solder image, and a blue solder image corresponding to each color illumination. Thereafter, the light intensity for each color of the solder is obtained from each of the solder images for colors. That is, one obtains the light intensity for each color of the solder due to the red solder image, the green solder image, and the blue solder image. The light intensity for each color of the solder can be obtained from a pixel corresponding to the solder or from a plurality of pixels included in a predetermined area of the solder. Then, a compensation ratio for each color of the solder is set according to a ratio between the light intensity for each color of the solder and an arbitrary reference light intensity, and the set compensation ratio for each color of the solder is stored. The reference light intensity may be set as the average light intensity of a plurality of soldering light intensities for each color. For example, the reference light intensity is set as an average light intensity of a red soldering light intensity obtained from the red soldering image, a green soldering light intensity obtained from the green soldering image, and a blue soldering light intensity obtained from the blue soldering image.

The compensation ratio obtained by the method described above for each color of the solder can be used to increase the accuracy of the measurement of the soldering area to be processed later. For example, after the color illuminations are irradiated onto the circuit board to obtain the color images and before the saturation map is formed by means of the color images, the color images are compensated by the compensation ratio for each color of the solder. That is, each of the color images is multiplied by the compensation ratio for each color of the solder, so that the unevenness of the light intensity for colors of the solder is compensated and a mistake in the measurement of the soldering area is reduced.

In this case, before obtaining the color images, the compensation ratio for each color of the color illuminations for correcting the color uniformity for the color illuminations and the compensation ratio for each color of the solder correcting solder for the color illuminations are predetermined by the above-described method and before the saturation map is formed For example, each of the color images is multiplied by the compensation ratio for each color of the color illumination and the compensation ratio for each color of the solder, so that the reliability of the measurement of the solder region is significantly increased.

As described above, the saturation map and the variance map are created by the color images obtained by the color illuminations, and the soldering area is set by the saturation map and the variance map, thereby increasing the accuracy of the measurement of the soldering area. In addition, before the measurement of the soldering area, at least one method of correcting the color uniformity for the color illuminations and correcting the solder uniformity for the color illuminations is performed, thereby increasing the accuracy of the measurement of the soldering area.

Various modifications and variations can be made in the present invention by those skilled in the art without departing from the spirit or scope of the invention. The present invention thus covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (8)

A method of measuring a solder area (1300), comprising: Irradiating a plurality of color illuminations onto a circuit board (1110) to obtain a plurality of color images (1210, 1220, 1230); Creating a saturation map (1300) by means of a chroma information obtained from the color images (1210, 1220, 1230) of each color; Setting a soldering area (1310) in the saturation map (1300) by means of a light intensity information obtained from the color images (1210, 1220, 1230) of each color; Generating a saturation average for each color in the solder region (1310); Creating a variance map (1400) using the saturation information for each color and the saturation average for each color; and Comparing a variance value on the variance map with a level value for creating a solder card (1500) showing the solder region (1310) in which a solder is formed. Method according to Claim 1 wherein irradiating the color illuminations onto the printed circuit board (1110) to obtain the color images (1210, 1220, 1230) respectively emit a red illumination, a green illumination and a blue illumination to obtain a respective red image (1210) of a green image (1220) and a blue image (1230). Method according to Claim 1 wherein hue information, saturation information and / or light intensity information for each color is obtained by color coordinate conversion of the color images (1210, 1220, 1230). Method according to Claim 1 wherein the step of defining a solder region (1310) comprises excluding a wiring pattern region (1320) and / or a dark solder mask region (1330) from the saturation map (1300) based on the light intensity information, wherein regions of particularly high light intensity information and / or particularly small light intensity information are relative be excluded to the light intensity information of the soldering area. Method according to Claim 1 Calculating each of the pixel variance values using the following equation: variance value for each pixel = abs (R-RA) + abs (G-GA) + abs (B-BA), where R, G and B are saturation information for each pixel and RA, GA and BA are saturation values for each color. Method according to Claim 1 wherein, prior to irradiating the color illuminations to the printed circuit board (1110) to obtain the color images (1210, 1220, 1230), the method further comprises the steps of: irradiating the color illuminations onto a target to obtain a plurality of illumination images for colors; Detecting a light intensity for each pixel with respect to each of the illumination images for colors; and setting a compensation ratio for each color corresponding to a ratio between the light intensity for each pixel and an arbitrary reference light intensity for each pixel, the compensation ratio being defined as a mean light intensity of an illumination image for each color to a light intensity of an associated pixel, and before the saturation map is created (1130) by means of the obtained color images (1210, 1220, 1230), further comprising compensating the color images (1210, 1220, 1230) by means of the compensation ratio for each color. Method according to Claim 1 wherein, prior to irradiating the color illuminations to the circuit board (1110) to obtain the color images (1210, 1220, 1230), the method further comprises the steps of: irradiating the color illuminations onto a solder formed on the circuit board (1110) to obtain a plurality of solder images for every color; Detecting a light intensity for each color of the solder from each of the solder images for each color; and determining a compensation ratio for each color of the solder corresponding to a ratio between the light intensity for each color of the solder and any reference light intensity, wherein the compensation ratio is defined as an average light intensity of light intensities for each color of the solder to the light intensity for each color of the solder, and before creating the saturation map (1300) using the obtained color images (1210, 1220, 1230), further comprising compensating the color images (1210, 1220, 1230) for the compensation ratio for each color of the solder. Method according to Claim 1 wherein, prior to irradiating the color illuminations to the printed circuit board (1110) to obtain the color images (1210, 1220, 1230), the method further comprises the steps of: defining a first compensation ratio for each color of the color illuminations to correct the color uniformity for the color illuminations; Compensation ratio is defined as an average light intensity of an illumination image for each color to a light intensity of an associated pixel; and determining a second compensation ratio for each color of solder to correct the solder uniformity for the color illuminations, wherein the second compensation ratio is defined as an average light intensity of light intensities for each color of the solder to the light intensity for each color of the solder; and before creating the saturation map (1300) using the obtained color images (1210, 1220, 1230), further comprising multiplying each color image by the compensation ratio for each color of the color illuminations and the compensation ratio for each color of the solder.

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