US20090216486A1

US20090216486A1 - Method for measuring three-dimension shape

Info

Publication number: US20090216486A1
Application number: US12/453,321
Authority: US
Inventors: Min Young Kim; Hee Tae Kim; Byung Min Yoo; Se Hyun Han; Seung Jun Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-01-26
Filing date: 2009-05-07
Publication date: 2009-08-27
Also published as: DE102007063932B4; DE102007004122B4; US7545512B2; US20070177159A1; DE102007004122A1; JP2007199070A; JP5733923B2; US20130128280A1; JP2010243508A

Abstract

A method of measuring a 3D shape, which can measure a 3D shape of target objects on a board by searching a database for bare board information when a measuring object is not set to a normal inspection mode or by performing bare board teaching when the board is supplied from a supplier having not the bare board information is provided. The method of measuring a 3D shape includes operation S100 of measuring a brightness of a first illumination source 41a, operation S200 of measuring a phase-to-height conversion factor, operation S300 of determining whether the measurement is performed in a normal inspection mode, operation S400 of measuring a 3D shape of a board 62 according to the normal inspection mode, operation S500 of determining whether bare board information about the board 62 is included, operation S600 of performing bare board teaching when the bare board information is excluded, operation S700 of measuring the 3D shape of target objects on the board 62 when the bare board information is included or bare board teaching information is generated, and operation S800 of analyzing whether the board 62 is normal or abnormal by using 3D shape information. Therefore, the 3D shape of target objects on the board may be more readily measured.

Description

RELATED APPLICATIONS

This application is a Continuation patent application of co-pending application Ser. No. 11/656,458, filed on 23 Jan. 2007. The entire disclosure of the prior application, Ser. No. 11/656,458, from which an oath or declaration is supplied, is considered a part of the disclosure of the accompanying Continuation application and is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
A method of measuring a 3D shape, which can measure 3D shape of target objects on a board by searching a database for bare board information when inspection option is set to the teaching-based inspection mode or by performing bare board teaching when the board from a supplier having not the bare board information is inspected.
2. Description of the Related Art
A method of measuring a 3D shape according to a conventional art will be described with reference to FIG. 1.
FIG. 1 is a flowchart illustrating a method of measuring a 3D shape according to the conventional art. Referring to, FIG. 1, to measure a 3D shape of a measuring object, in operation S10, a grating pattern illumination is emitted towards a reference surface by emitting a light generated from an illumination source (not shown) towards a grating device (not shown) to acquire a reference phase corresponding to the reference surface. In operation S11, a grating is moved by a fine pitch using a piezoelectric actuator (not shown) and emitted towards the reference surface and a grating pattern image is acquired using a charged coupled device (CCD) camera and a grabber (not shown). In operation S12, when the grating pattern image is acquired by the grabber, a bucket algorithm is applied to the grating pattern image. In operation S13, the reference phase with respect to the reference surface is acquired.
In operation S15, when the reference phase corresponding to the reference surface is acquired, a measuring object is placed on a moving table and a light generated from the illumination source is emitted towards a measuring surface of the measuring object to acquire a phase of the measuring object. In operation S16, the grating is moved by a fine interface using the piezoelectric actuator to apply the bucket algorithm, and the grating pattern image reflected from the measuring surface is acquired via the CCD camera and the grabber. In operation S17, the bucket algorithm is applied to the grating pattern image. In operation S18, an object phase of the measuring object is acquired.
When the object phase is acquired, the object phase is deducted from the reference phase in operation S21, and a moire phase is acquired in operation S21. When the moire phase is acquired, the moire phase is unwrapped in operation S22, and actual height information of the measuring object is acquired by using a result of unwrapping. Through the above-described operations, the 3D shape of the measuring object is acquired.
However, the conventional 3D shape measuring method has a problem in that an operator may feel tired a lot, and a productivity may be reduced since each of measuring conditions is manually calculated and then measurement is performed when a totally new measuring object, not an ongoing measuring object, is measured.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a method of measuring a 3D shape which can measure 3D shape of target objects according to the normal inspection mode when a measuring object is set to the normal inspection mode, and also can measure the 3D shape of target objects on the board by searching a database for bare board information when the inspection option is set to the teaching-based inspection mode or by performing bare board teaching when the board is inspected from a supplier having not the bare board information, and thereby can improve a productivity of electronic board manufacturing line.
Another objective of the present invention is to improve the measurement quality of the 3D shape of target objects by measuring their 3D shape with a regular brightness of an illumination source at each illumination level, which is predefined prior to the machine operation.
To accomplish the above objects of the present invention, there is provided a method of measuring a 3 dimensional (3D) shape, the method including: measuring a brightness of a first illumination source by controlling via a central control unit a module control unit and an image acquisition unit; measuring a phase-to-height conversion factor by controlling via the central control unit the module control unit and the image acquisition unit after the brightness measuring process of the first illumination source is completed; determining whether the measurement is performed in a normal inspection mode after the brightness of the first illumination source and the phase-to-height conversion factor are measured and calculated; measuring a 3D shape of a board according to the normal inspection mode by controlling, via the central control unit, the module control unit and the image acquisition unit when it is the normal inspection mode as a result of the determination; searching a database and determining, via the central control unit, whether bare board information about the board is in the database when it is not the normal inspection mode as a result of the determination; performing bare board teaching by controlling, via the central control unit, the module control unit and the image acquisition unit when the bare board information is not in the database; measuring the 3D shape of the board according to a teaching-based inspection mode by controlling, via the central control unit, the module control unit and the image acquisition unit when the bare board information is in the database or when bare board teaching information is generated by performing the bare board teaching; and analyzing via the central control unit whether 3D shape of target objects on the board is normal or abnormal by using the measured 3D shape information of the objects according to the normal inspection mode and the teaching-based inspection mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become apparent from the following description of a preferred embodiment given in conjunction with the accompanying drawings, in which:

FIG. 1 is a flowchart illustrating a method of measuring a 3D shape according to a conventional art;

FIG. 2 is a diagram illustrating a 3D shape measuring system for a 3D shape measuring method according to the present invention;

FIGS. 3A through 3C illustrate a configuration of a board, a bare board, and a calibration target;

FIG. 4 is a flowchart illustrating a method of measuring a 3D shape according to the present invention;

FIG. 5 is a flowchart illustrating an operation of measuring a brightness of a first illumination source shown in FIG. 4;

FIG. 6 is a flowchart illustrating an operation of measuring a phase-to-height conversion factor shown in FIG. 4;

FIGS. 7A and 7B are flowcharts illustrating an operation of measuring a 3D shape of a board according to a normal inspection mode shown in FIG. 4;

FIGS. 8A and 8B are flowcharts illustrating a bare board teaching operation shown in FIG. 4; and

FIGS. 9A and 9B are flowcharts illustrating an operation of measuring a 3D shape of a board according to a teaching-based inspection mode shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 is a diagram illustrating a 3D shape measuring system for a 3D shape measuring method according to the present invention. As shown in FIG. 2, the 3D shape measuring apparatus includes a central control unit 10, a module control unit 20, an image acquisition unit 30, at least one pattern projector 40, a second illumination source 50, an X-Y table 61, a table moving device 60, and a camera 70. Hereinafter, a configuration of each element will be described.
A charge coupled device (CCD) camera or a complementary metal oxide semiconductor (CMOS) camera is utilized for the camera 70. A second illumination source 50, an optical filter 71, and a lens 72 are provided below the camera 70. A plurality of light emitting diodes (LEDs) formed in a shape of a circle or a circular lamp is utilized for the second illumination source 50, and the second illumination source 50 is utilized as an illuminator to measure particular shape of specific locations on a board 62 or a bare board 63 which corresponds to a measuring object.
The table moving device 60 drives the X-Y table 61 which is positioned below the camera 70 and thereby moves the board 62, the bare board 63, or a calibration target 64 to predefined measurement locations so that the camera 70 may take images of the board 62, the bare board 63 or the calibration target 64.
At least one pattern projector 40 of the 3D shape measuring system, which is indicated by a solid line and a dotted line as shown in FIG. 2, is provided. Each of the at least one pattern projector 40 is provided to be inclined in one side or another side of the camera 70 which takes images of the board 62, the bare board 63 or the calibration target 64. In this instance, the pattern projector 40 includes an illumination part 41, a grating moving device 42, a grating device 43, and a lens 44. The illumination part 41 includes a first illumination source 41 a and a plurality of lenses 41 b and 41 c. An illumination generated from the first illumination source 41 a passes through the plurality of lenses 41 b and 41 c, and is emitted toward the grating device 43 and then toward the board 62, the bare board 63 or the calibration target 64.
The image acquisition unit 30 receives the image taken by the camera 70 and transmits the received image to the central control unit 10. The module control unit 20 includes a table controller 21, a grating controller 22, and an illumination controller 23. The illumination controller 23 controls the first illumination source 41 a of the illumination part 41 or the second illumination source 50, the grating controller 22 controls the grating moving device 42, and the table controller 21 controls the table moving device 60.
The central control unit 10 includes a control board 11, an image processing board 12, and an interface board 13. The central control unit 10 transmits/receives a control signal or control information to the module control unit 20 and the image acquisition unit 30 via the interface board 13, the image processing board 12 processes an image received from the image acquisition unit 30, and the control board 11 generally controls the 3D shape measuring apparatus of the present invention. Also, the central control unit 10 searches a database 80 for bare board information of a new board supplier or stores the bare board information which is acquired in a teaching-based inspection mode.
Hereinafter, a method of measuring 3D shape of target objects on the board 62 by using the 3D shape measuring system constructed as above will be described with reference to FIGS. 2 through 4.
FIG. 2 is a diagram illustrating a 3D shape measuring system for a 3D shape measuring method according to the present invention, FIGS. 3A through 3C illustrate a configuration of a board, a bare board, and a calibration target, and FIG. 4 is a flowchart illustrating a method of measuring a 3D shape according to the present invention.
As shown in FIGS. 2 through 4, an initial setup operation of the 3D shape measuring system according to the present invention is performed before measuring the 3D shape. For the initial setup operation, in operation S100, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to measure a brightness of the first illumination source 41 a. In operation S200, when the brightness of the first illumination source 41 a is completely measured, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to measure a phase-to-height conversion factor. Through operations S100 and S200, the initial setup operation of the 3D shape measuring system is completed.
In operation S300, after the brightness of the first illumination source 41 a and the phase-to-height conversion factor are measured for the initial setup operation of the 3D shape measuring system, the central control unit 10 determines whether the measurement is performed in a normal inspection mode. When an operator selects a normal inspection mode or a teaching-based inspection mode, by using input information via an input device, such as a keyboard (not shown), or by using an job program pre-installed in the 3D shape measuring system, the central control unit 10 recognizes and determines the selected mode.
In operation S400, when the central control unit 10 determines it is the normal inspection mode in operation S300, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to measure the 3D shape of target objects on the board 62 according to the normal inspection mode. Conversely, when the central control unit 10 determines it is not the normal inspection mode in operation S300, the central control unit performs operation S500 of searching the database 80 for bare board information of the board 62.
In operation S510 of operation S500, the table controller 21 of driving the table moving device 60 controls the X-Y table 61 to move the board 62 to a measurement location. In operation S520, when the board 62 is moved to the measurement location, the central control unit 10 controls the illumination controller 23 to switch on the second illumination source 50. In operation S530, when the second illumination source 50 is switched on and thereby the camera 70 takes a picture of the board 62 and the image acquisition unit acquires an image, the central control unit 10 calculates location information about a particular part of the board 62. In this instance, the particular part of the board 62 or the bare board 63 indicates a mark (not shown) which can be distinguishable for each manufacturer or each product adopting the board 62 or the bare board 63. In operation S540, when the location information about the particular part of the board 62 is calculated, the central control unit 10 searches the database 80 for bare board information which is identical to the image information of the particular part. In operation S550, it is determined whether the database 80 contains the bare board information about the board 62 to be currently measured.
In operation 600, when the database 80 excludes the bare board information in operation S500, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to perform a bare board teaching.
In operation 700, when the database 80 includes the bare board information in operation S500 or bare board teaching information is generated in operation S600, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to measure the 3D shape of target objects on the board 62. When the 3D shape of the board 62 is measured in each of operations S400 and S700, the central control unit 10 analyzes whether the board 62 is normal or abnormal by using information about the measured 3D shape in operation S800 and thereby badness of a solder 62 e, which is formed on the board 62 after measuring the 3D shape of the board 62, is determined. As described above, since the 3D shape of target objects on the board 62 is measured according to the normal inspection mode or the teaching-based inspection mode, the 3D shape of target objects on the board may be more readily and efficiently acquired.
Hereinafter, operations S100, S200, S400, S600, and S700 in a method of measuring a 3D shape according to the present invention will be sequentially described in detail
As shown in FIGS. 2 through 5, in operation S110 of operation S100, the central control unit 10 sets a range of an illumination adjustment command value and then a brightness of the first illumination source 41 a is adjusted by the illumination controller 23 of the module control unit 20 according to the set adjustment command value.
The calibration target 64 is utilized to adjust the brightness of the first illumination source 41 a. As shown in FIG. 3C, the calibration target 64 includes a plane surface 64 a and a stepped difference 64 b, and is formed in a gray color. Also, the calibration target 64 is applied when measuring the brightness of the first illumination source 41 a or calculating the phase-to-height conversion factor in the initial setup operation for measuring the 3D shape. In operation S111, to measure the brightness of the first illumination source 41 a using the calibration target 64, the table controller 21 of the module control unit to drive the table moving device 60 drives the X-Y table 61 and the calibration target 64 is moved to a measurement location. In this instance, the measurement location indicates a location where the camera 70 may take an image of the calibration target 64.
In operation S112, when the calibration target 64 is moved to the measurement location, the first illumination source 41 a is switched on by the illumination controller 23 of the module control unit 20. In operation S113, when the first illumination source 41 a is switched on, the central control unit 10 sets the ranges of the illumination adjustment command value. In this instance, when a user inputs information about the adjustment command value using an input device, such as a keyboard (not shown), and the like, the central control unit 10 recognizes the input information and sets the range of the adjustment command value. In operation S114, when the range of the illumination adjustment command value is set, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the set adjustment command value.
In operation S120, when the brightness of the first illumination source 41 a is adjusted, the grating controller 22 of the module control unit 20 to drive the grating moving device 42 moves the grating device 43 an N number of times and the camera 70 takes an image of the calibration target 64 for each movement and the image acquisition unit 30 acquires the image of the calibration target 64. In operation S130, when the image acquisition unit 30 acquires N images of the calibration target 64, the acquired image is received via the image processing board 12 and the interface board 13 of the central control unit 10 and average-process of the received images is performed, and an average image is calculated. In this instance, the average image process acquires an average image where a grating pattern is eliminated from the N number of images taken by the camera 70 every time the grating device 43 is moved the N number of times to acquire the image of the calibration target 64. In the present invention, the image of the calibration target 64 is acquired by moving the grating device 43 at least four times and the average image process is performed.
In operation S140, when the average image of the calibration target 64 is calculated, the central control unit 10 sets a representative brightness value of the calculated average image to an illumination brightness of a corresponding illumination adjustment command value. In operation S150, when the illumination brightness is set, the central control unit 10 determines whether the adjustment command value is maximum. When the illumination adjustment command value is maximum within the set range of the adjustment command value, the central control unit 10 determines the brightness adjustment of the first illumination source 41 a is completed.
In operation S160, when the illumination adjustment command value is maximum, the central control unit 10 defines the illumination brightness corresponding to each adjustment command value. In operation S170, when the illumination brightness corresponding to each adjustment command value is defined, the central control unit 10 generates the illumination brightness corresponding to each adjustment command value into an illumination index table. In this instance, the illumination index table defines the illumination brightness according to each adjustment command value. Therefore, when measuring the 3D shape of the board 62 or the bare board 63 by using the first illumination source 41 a, the illumination brightness may be linearly adjusted by using the brightness index table, and thus the measurement quality of a 3D shape may be improved.
When a plurality of first illuminations sources 41 a is provided as indicated by a solid line and a dotted line as shown in FIG. 2, in operation S161 of operation S160, the central control unit 10 determines whether the plurality of first illumination sources 41 a is provided. In operation S162, when the plurality of first illumination sources 41 a is provided, any one of the plurality of first illumination sources 41 a is switched off and any one of remaining first illumination sources 41 a is switched on. Specifically, when any one of the plurality of first illumination sources 41 a indicates the first illumination source 41 a indicated by the solid line in FIG. 2, the remaining first illumination source 41 a is indicated by the dotted line in FIG. 2.
In operation S163, when the remaining first illumination source 41 a is switched on, the central control unit 10 determines whether the adjustment command value of the remaining first illumination source 41 a is maximum. In operation S164, when the adjustment command value of the remaining first illumination source 41 a is maxim, the central control unit 10 compares the illumination brightness values corresponding to each of the adjustment command value of any one of the plurality of first illumination sources 41 a and the adjustment command value of the remaining first illumination source 41 a, and selects a smaller illumination brightness value between them as the brightness of the total illumination system according to each adjustment command value. In operation S165, when the illumination brightness of the total illumination system corresponding to each adjustment command value is determined, the central control unit 10 calculates new adjustment command value of each first illumination corresponding to the selected illumination brightness of the total illumination system, and then redefines the illumination adjustment command values of the plurality of first illumination sources 41 a corresponding to the selected illumination brightness of the total illumination system. Through the above-described operations, the illumination brightness defined for each adjustment command value is generated into the illumination index table.
In operation S200, when the brightness measurement of the first illumination source 41 a is completed, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to measure the phase-to-height conversion factor. As shown in FIGS. 2 through 4 and FIG. 6, operation S210 of controlling, by the central control unit 10, the illumination controller 23 of the module control unit 20 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value of the total illumination system is performed.
More specifically, to adjust the brightness of the first illumination source, in operation S211, the table controller 21 of driving the table moving device drives the X-Y table 61 and thus the calibration target 64 is moved to the measurement location. In operation S212, when the calibration target 64 is moved to the measurement location, the first illumination source 41 a is switched on by the illumination controller 23. In operation S213, when the first illumination source 41 a is switched on, the central control unit 10 selects an adjustment command value. In operation S214, when the adjustment command value is selected, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a to the illumination brightness corresponding to the selected adjustment command value.
In operation S220, when the first illumination source is adjusted, the central control unit 10 determines whether a measurement portion of the calibration target 64 corresponds to a plane surface 64 a. Whether the measurement portion of the calibration target 64 corresponds to the plane surface 64 a is determined by the central control unit 10 by using the image, taken by the camera 70, in a state where the second illumination source 50 is switched on. When the measurement portion of the calibration target 64 does not correspond to the plane surface 64 a, the central control unit 10 drives the table moving device 60 to move the plane surface 64 a of the calibration target 64 to a focus location of the camera 70 or the plane surface 64 a is manually moved by the operator.
In operation S230, when the measurement portion of the calibration target 64 corresponds to the plane surface 64 a, the central control unit 10 sets the plane surface 64 a of the calibration target 64 as an inspection area. In operation S240, when the plane surface 64 a of the calibration target 64 is set as the inspection area, the grating controller 22 of driving the grating moving device 42 moves the grating device 43 the N number of times, emits a grating pattern illumination towards the plane surface 64 a for each movement and takes an image of the calibration target via the camera 70, which is reflected from the plane surface 64 a. The image acquisition unit 30 acquires the taken images of the plane surface 64 a. In operation S250, when the image acquisition unit 30 acquires the images of the plane surface 64 a, the central control unit 10 acquires a phase map of the plane surface 64 a by using an N-bucket algorithm and the acquired images, and also stores the phase map of a first reference surface m. Information, such as the phase map of the first reference surface m, is stored in a storage device (not shown), such as a hard disk that connects with the control board 11 of the central control unit 10, and the like.
When the phase map of the first reference surface m of the plane surface 64 a is stored, operation S220 is re-performed. In operation S260, when the measurement portion does not correspond to the plane surface 64 a, the central control unit 10 sets a stepped difference 64 b of the calibration target 64 as the inspection area. In operation S270, when the stepped difference 64 b is set as the inspection area, the grating controller 22 of driving the grating moving device 42 moves the grating device 43 the N number of times, emits a grating pattern illumination towards the stepped difference 64 b for each movement and takes an image of the calibration target 64 via the camera 70, which is reflected from the stepped difference 64 b. The image acquisition unit 30 acquires the taken images of the stepped difference 64 b. In operation S280, when the image acquisition unit 30 acquires the images of the stepped difference 64 b, the central control unit 10 acquires a phase map of the stepped difference 64 b by using an N-bucket algorithm and the acquired images.
In operation S290, when the phase map of each of the plane surface 64 a and the stepped difference 64 b are acquired in each of operations S250 and S280, the phase-to-height conversion factor of each pixel is calculated and stored by using the acquired phase maps. In this instance, the phase-to-height conversion factor is required to convert a phase into a height value when calculating a phase of each point by using the N-bucket algorithm and then calculating the height value of a corresponding point by using the calculated phase. To calculate the phase-to-height conversion factor of each pixel, the central control unit 10 calculates a relative height phase of the stepped difference 64 b with respect to the first reference surface m by using phase information about the first reference surface m and the phase map of the stepped difference 64 b. When the relative height phase of the stepped difference 64 b is calculated, the central control unit 10 calculates the phase-to-height conversion factor by using the relative height phase of the stepped difference 64 b, pattern period information of the stepped difference 64 b, and a known height of the stepped difference 64 b of the calibration target 64.
Operation S290 is performed with respect to each of the plurality of first illumination sources 41 a when the plurality of first illumination sources 41 a as indicated by the solid line and the dotted line in FIG. 2 is provided. More specifically, when the plurality of first illumination sources 41 a is provided, in operation S291, the phase-to-height conversion factor of each pixel is calculated by using the phase map, which is acquired according to the grating pattern illumination generated from any one of the first illumination sources 41 a.
In operation S292, when the phase-to-height conversion factor of each pixel is calculated, the central control unit 10 determines whether the plurality of first illumination sources 41 a is provided. In operation S293, when the phase-to-height conversion factor of each pixel according to any one of the plurality of first illumination sources 41 a is calculated, the central control unit 10 controls the illumination controller 23 of the module control unit 20 to switch off any one of the plurality of first illumination sources 41 a where the phase-to-height conversion factor is calculated, and switch on a remaining first illumination source 41 a.
In operation S294, when the remaining first illumination source 41 a is switched on, the central control unit 10 determines whether the phase-to-height conversion factor of each pixel according to the grating pattern illumination from the remaining first illumination source 41 a is calculated. In operation S295, when the phase-to-height conversion factor of each pixel is calculated, the central control unit 10 stores the phase-to-height conversion factor of each pixel according to each of the plurality of first illumination sources 41 a.
When the phase-to-height conversion factor of each pixel was not calculated, the central control unit 10 returns to operation S210 of controlling the illumination controller 23 of the module control unit 20 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value.
When the illumination index table is generated and the phase-to-height conversion factor is calculated, operation S400 of measuring the 3D shape of target objects on the board 62 according to the normal inspection mode is performed. More specifically, in operation S410 of operation S400, as shown in FIGS. 2 through 4 and FIGS. 7A and 7B, the table controller 201 of driving the table moving device 60 drives the X-Y table 61, and the board 62 is moved to the measurement location.
In operation S420, when the board 62 is moved to the measurement location, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value. In operation S430, when the brightness of the first illumination source 41 a is adjusted, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to acquire the phase map of the board 62, and calculates the relative height phase with respect to a first reference surface m. In operation S440, when the relative height phase with respect to the first reference surface m is calculated, the central control unit 10 calculates a phase histogram by using the relative height phase with respect to the first reference surface m, and calculates the 3D shape of target objects on the board 62 by using the calculated phase histogram.
In operation S442 of operation S440 in FIG. 7A, when a single first illumination source 41 a is provided, and in this instance, the relative height phase with respect to the first reference surface m of the board 62 according to the grating pattern illumination generated from the first illumination source 41 a is calculated, the central control unit 10 calculates a phase histogram by using the relative height phase with respect to the first reference surface m. In operation S443, when the phase histogram is calculated, the central control unit 10 separates a second reference surface n and a solder 62 e from the calculated phase histogram, and calculates a centroid of the second reference surface n and the solder 62 e.
In this instance, the method of calculating the centroid of the second reference surface n and the solder 62 e initially separates the second reference surface n and the solder 62 e by using pre-stored dimensional information of the board 62. When the second reference surface n is calculated, the central control unit 10 separates the solder 62 e by using the calculated second reference surface n. When the second reference surface n and the solder 62 e are separated, the central control unit 10 calculates the centroid of the second reference surface n and the solder 62 e by using a centroid method.
In operation S444, when the centroid of the second reference surface n and the solder 62 e is calculated, the central control unit 10 calculates a representative height of the solder 62 e by using the centroid of the second reference surface n and the centroid of the solder 62 e. In operation S445, when the representative height of the solder 62 e is calculated, the central control unit 10 calculates a volume, a height distribution, and an positional offset of the solder 62 e by using the calculated representative height.
Hereinafter, performing operation S440 in FIGS. 7B when the plurality of first illumination sources 41 a is provided will be described in detail.
In operation S441, when the plurality of first illumination sources 41 a is provided, and the relative height phase with respect to the first reference surface m of the board 62 according to the grating pattern illumination generated from any one of the plurality of first illumination sources 41 a and the relative height phase with respect to the first reference surface m of the board 62 according to the grating pattern illumination generated from the remaining first illumination source 41 a are calculated, the central control unit 10 calculates a combined height phase where noise is removed from the relative height phase with respect to the first reference surface m according to each of the plurality of first illumination sources 41 a, and stores the calculated combined height phase.
In operation S442, when the combined height phase is stored, the central control unit 10 calculates a phase histogram by using the stored combined height phase, which is the same as when only the single first illumination source 41 a is provided. In operation S443, the central control unit 10 separates the second reference surface n and the solder 62 e from the calculated phase histogram, and calculates the centroid of the second reference surface n and the solder 62 e. Next, as described above, in operation S444, the central control unit 10 calculates the representative height of the solder 62 e by using the centroid of the second reference surface n and the centroid of the solder 62 e. In operation S445, when the representative height of the solder 62 e is calculated, the central control unit 10 calculates a volume, a height distribution, and an positional offset of the solder 62 e by using the calculated representative height.
In this instance, the height distribution of the solder 62 e is calculated based on the second reference surface n, and the volume of the solder 62 e is calculated by multiplying the phase-to-height conversion factor of each pixel and phase information of the solder 62 e, and summing up the results of the multiplications. Also, the positional offset of the solder 62 e is calculated depending upon how far the solder 62 e is located from the center of a conductive pad 62 d by using location information of the solder 62 e which is calculated by using the volume of the solder 62 e. Based on the calculated volume, height, distribution and positional offset information of solder, the goodness and badness of the board is determined automatically.
In operation S600, when the bare board information is excluded in operation S500, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to perform a bare board teaching.
As shown in FIGS. 2 through 4, and FIGS. 8A and 8B, the bare board 63 is moved to the measurement location in operation S600. Specifically, in operation S610, the table controller 21 of driving the table moving device 60 drives the X-Y table 61 whereby the bare board 63 is moved to the measurement location. To distinguish the bare board 63 from the board 62, the bare board 63 includes a base plate 62 a, a conductive pattern 62 b, a solder mask 62 c, and the conductive pad 62 d.
In operation S620, when the bare board 63 is moved to the measurement location, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value. In operation S630, when the brightness of the first illumination source 41 a is adjusted, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to acquire the phase map of the bare board 63, and calculates the relative height phase with respect to the first reference surface m. In this instance, the first reference surface m indicates the base plate 62 a of the bare board 63, and is calculated by using pre-given bare board information.
In operation S640, when the relative height phase with respect to the first reference surface m is calculated, the central control unit 10 stores location information and image information about a particular part of the bare board 63, as bare board information, in the database 80.
In this instance, operation S640 may be performed in a different way with respect to when only a single first illumination source 41 a is provided and when a plurality of first illumination sources 41 a is provided. Initially, performing operation S640 when the single first illumination source 41 a is provided will be described. In operation S642, when the relative height phase with respect to the first reference surface m is calculated, the central control unit 10 stores the relative height phase with respect to the first reference surface m as height phase information of the bare board 63. In operation S643, when the height phase information is stored, the central control unit 10 determines whether teaching with respect to all areas of the bare board 63 is completed. In operation S644, when the teaching with respect to all areas of the bare board 63 is completed, the central control unit 10 controls the illumination controller 23 of the module control unit 21 to switch off the first illumination source 41 a and switch on the second illumination source 50. In operation S645, when the second illumination source 50 is switched on, the central control unit 10 controls the image acquisition unit 30 to acquire the image with respect to the particular part of the bare board 63 using the camera 70, and stores the acquired image, and also calculates location information with respect to the particular part of the bare board 63, and stores the calculated location information and the image information in the database 80.
Hereinafter, performing operation S640 when the plurality of first illumination sources 41 a is provided will be described. In this instance, in operation S641, when the relative height phase with respect to the first reference surface m of the bare board 63 according to any one of the plurality of first illumination sources 41 a and the relative height phase with respect to the first reference surface m of the bare board 63 according to a remaining first illumination sources 41 a are calculated, the central control unit 10 calculates the combined height phase where noise is removed from the relative height phase with respect to each first reference surface m. Operations after calculating the combined height phase are identical when only the single first illumination source 41 a is provided. In operation S642, when the combined height phase is calculated, the central control unit 10 stores the calculated combined height phase as height phase information.
In operation S643, when the height phase information is stored, the central control unit 10 determines whether teaching with respect to all areas of the bare board 63 is completed. In operation S644, when the teaching with respect to all areas of the bare board 63 is completed, the central control unit 10 controls the illumination controller 23 of the module control unit 21 to switch off the plurality of first illumination sources 41 a and switch on the second illumination source 50. In this instance, all of the plurality of first illumination sources 41 a is switched off. Also, in operation S645, when the second illumination source 50 is switched on, the central control unit 10 controls the image acquisition unit 30 to acquire the image with respect to the particular part of the bare board 63 using the camera 70, and stores the acquired image, and also calculates location information with respect to the particular part of the bare board 63, and stores the calculated location information in the database 80.
Hereinafter, operation S700 of measuring the 3D shape of target objects on the board 62 according to a teaching-based inspection mode when the bare board information is included in operation S500 will be described with reference to FIGS. 2 through 4, and FIGS. 9A and 9B.
In operation S710 of operation S700, bare board information corresponding to the board 62 is read from the database 80. In operation S720, when the bare board information of the board 62 is read, the central control unit 10 controls the illumination controller 23 of the module control unit to switch off the second illumination source 50 when the second illumination source 50 is switched on. In operation S730, when the second illumination source 50 is switched off, the table controller 21 of driving the table moving device 60 drives the X-Y table 61 whereby the board 62 is moved to the measurement location.
In operation S740, when the board 62 is moved to the measurement location, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value. In operation S750, when the brightness of the first illumination source 41 a is adjusted, the central control unit 10 controls the module control unit 20 and the image acquisition unit 30 to acquire the phase map of the board 62 and calculates the relative height phase with respect to the first reference surface m. In operation S760, when the relative height phase with respect to the first reference surface m is calculated, the central control unit 10 calculates the phase histogram by using the relative height phase with respect to the first reference surface m, and calculates the 3D shape of the board 62.
In this instance, operation S760 may be performed in a different way with respect to when only a single first illumination source 41 a is provided and when a plurality of first illumination sources 41 is provided.
Initially, performing operation S760 when only the single first illumination source 41 a is provided will be described. In operation S762, when the relative height phase with respect to the first reference surface m of the board 62 according to the grating pattern illumination generated from the first illumination source 41 a is calculated, the central control unit 10 stores the relative height phase with respect to the first reference surface m as height phase information of the board 62. In operation S763, when the height phase information of the board 62 is stored, the central control unit 10 separates height phase information of the solder 62 e in a corresponding inspection location by using the height phase information of the bare board 63 in the database 80 and the height phase information of the board 62 stored in operation S762. When the height phase information of the solder 62 e is separated in the corresponding inspection location, the central control unit 10 calculates actual height information from the relative height phase information of the solder 62 e, and calculates a volume, a height distribution, and an positional offset of the solder 62 e by using the calculated actual height information. Specifically, in operation S764, when the height phase information of the solder 62 e is separated, the central control unit 10 calculates the actual height information from the separated height phase information of the solder 62 e, and calculates the volume, the height distribution, and the positional offset of the solder 62 e.
Hereinafter, performing operation S760 when the plurality of first illumination sources 41 a is provided will be described. In operation S761, when the relative height phase with respect to the first reference surface m of the board 62 according to any one of the plurality of first illumination sources 41 a and the relative height phase with respect to the first reference surface m of the board 62 according to a remaining first illumination source 41 a are calculated, the central control unit 10 calculates a combined height phase where noise is removed from the relative height phase with respect to each first reference surface m. Following operations will be identical when only the single first illumination source 41 a is provided and thus only a brief description will be made below.
In operation S762, when the combined height phase is calculated, the central control unit 10 stores the calculated combined height phase as height phase information. In operation S763, when the height phase information is stored, the central control unit 10 separates height phase information of the solder 62 e by using the height phase information of the bare board 80 stored in the database 80 and the height phase information of the board 62 stored in operation S762. In operation S764, when the height phase information of the solder 62 e is separated, the central control unit 10 calculates actual height information from the separated height phase information of the solder 62 e and calculates the volume, the height distribution, and the positional offset of the solder 62 e.
In a method of measuring a 3D shape, operations S420, S620, and S740 of adjusting the brightness of the first illumination source 41 a, to determine goodness and badness of the board 62, will be further described in detail with reference to FIGS. 7A through 9B.
Operations S420, S620, and S740 may be performed in a different way with respect to when a single first illumination source 41 a is provided and when a plurality of first illumination sources 41 a is provided. Hereinafter, performing operations S420, S620, and S740 when the single first illumination source 41 a is provided will be described with reference to FIGS. 7A, 8A, and 9A.
In operations S422, S622, and S742 of operations S420, S620, and S740, the central control unit 10 controls the illumination controller 23 to switch on the first illumination source 41 a. In operations S423, S623, and S743, when the first illumination source 41 a is switched on, the central control unit 10 selects a pre-input adjustment command value. In operations S424, S624, and S744, when the adjustment command value is selected, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value.
Hereinafter, operations S420, S620, and S740 when the plurality of first illumination sources 41 a is provided will be described with reference to FIGS. 7B, 8B, and 9B.
In operations S421, S621, and S741 of operations S420, S620, and S740, the central control unit 10 determines whether any one of the plurality of first illumination sources 41 a is selected. In operations S422, S622, and S722, when the selected first illumination source 41 a is determined, the central control unit 10 controls the illumination controller 23 to switch on the selected first illumination source 41 a. In operations S423, S623, and S743, when the selected first illumination source 41 a is switched on, the central control unit 10 selects the pre-input adjustment command value. In operations S424, S624, and S744, when the adjustment command value is selected, the central control unit controls the illumination controller 23 to adjust the brightness of the first illumination source 41 a according to the selected adjustment command value.
In operations S425, S625, and S745, when any one of the plurality of first illumination sources 41 a is not selected, the central control unit 10 controls the illumination controller 23 to switch on a remaining first illumination source 41 a. In operation S426, S626, and S746, when the remaining first illumination source 41 a is switched on, the central controls unit 10 selects the pre-input adjustment command value. In operations S427, S627, and S747, when the adjustment command value is selected, the central control unit 10 controls the illumination controller 23 to adjust the brightness of the remaining first illumination source 41 a according to the selected adjustment command value.
When the brightness of the first illumination source 41 a is adjusted, operations S430, S630, and S750 of calculating the relative height phase with respect to the first reference surface m are performed respectively. In this instance, operations S430, S630, and S750 may be performed in a different way with respect to when a single first illumination source 41 a is provided and when a plurality of first illumination sources 41 a is provided. Hereinafter, performing operations S430, S630, and S750 when the single first illumination source 41 a is provided will be described with reference to FIGS. 7A, 8A, and 9A.
In operations S431, S631, and S751, when the brightness of the first illumination source 41 a is adjusted, the grating controller 22 of driving the grating moving device 42 moves the grating device 43 the N number of times and the camera 70 takes an image, which is reflected by emitting a grating pattern illumination generated from the first illumination source 41 a, every movement, and the image acquisition unit 30 acquires the taken image. In operations S432, S632, and S752, when the image acquisition unit 30 acquires the image, an inspection area is expanded. A concept of expanding the inspection area is applied to calculate the height of the solder 62 e based on the second reference surface n of the board 62 that includes the conductive pattern 62 b, the solder mask 62 c, the conductive pad 62 d, and the solder 62 e, which are formed on the base plate 62 a, as shown in FIG. 3A. In this instance, the second reference surface n indicates the height from a bottom surface of the board 62 to a top surface of the solder mask 62 c and the conductive pad 62 d, and the height corresponding to a centroid from the first reference surface m to the solder mask 62 c and the conductive pad 62 d. Also, as shown in FIGS. 3A and 3B, when an area A is set as the inspection area of the board 62 or the bare board 63 and the inspection is started, the inspection area is expanded to an area B so as to calculate a height value of the second reference value n.
In operations S433, S633, and S753, when the image acquisition unit 30 acquires the image in operations S431, S631, and S751, the central control unit 10 calculates a phase map by using an N-bucket algorithm, and stores the calculated phase map. In operations S434, S634, and S754, when the phase map is calculated and stored, the central control unit 10 calculates the relative height phase with respect to the first reference surface m in a corresponding inspection location by using a difference between a pre-stored phase map of the first reference surface m and the phase map stored in the central control unit 10.
Hereinafter, performing operations S430, S630, and S750 when the plurality of first illumination sources 41 a is provided will be described with reference to FIGS. 7B, 8B, and 9B.
In operations S431, S631, and S751, when the brightness of any one of the plurality of first illumination sources 41 a is adjusted, the grating controller 22 of driving the grating moving device 42 moves the grating device 43 the N number of times and the camera 70 takes an image, which is reflected by emitting a grating pattern illumination generated from the first illumination source 41 a, every movement, and the image acquisition unit 30 acquires the taken image. In operations S432, S632, and S752, when the image acquisition unit 30 acquires the image, an inspection area is expanded. In operations S433, S633, and S753, when the image acquisition unit 30 acquires the image in operations S431, S631, and S751, the central control unit 10 calculates a phase map by using an N-bucket algorithm and stores the calculated phase map. In operations S434, S634, and S754, when the phase map is calculated and stored, the central control unit 10 calculates the relative height phase with respect to the first reference surface m in a corresponding inspection location by using a difference between a pre-stored phase map of the first reference surface m and the phase map stored in the central control unit 10.
In operations S435, S635, and S755, when the brightness of a remaining first illumination source 41 a is adjusted, the grating controller 22 of driving the grating moving device 42 moves the grating device 43 the N number of times and the camera 70 takes an image, which is reflected by emitting a grating pattern illumination generated from the remaining first illumination source 41 a, every movement, and the image acquisition unit 30 acquires the taken image. When the image according to the remaining first illumination source 41 a is acquired by the image acquisition unit 30, the relative height phase according to the remaining first illumination source 41 a is calculated by performing operations S436, S636, and S756 of expanding the inspection area, operations S437, S637, and S757 of calculating and storing the phase map using N-bucket algorithm, and operations S438, S638, and S758 of calculating the relative height phase with respect to the first reference surface m.
When the relative height phase is calculated with respect to when the single first illumination source 41 a is provided to the 3D shape measuring system and when the plurality of first illumination sources 41 a is provided thereto, the 3D shape of target objects on the board 62 can be measured by using the calculated relative height phase. Also, goodness and badness of the solder 62 e of the board 62 can be determined by using the result of the measurement.
According to the present invention, there is provided a method of measuring a 3D shape which can measure 3D shape of target objects on a board according to a normal inspection mode when a measuring object is set to the normal inspection mode, and also can measure the 3D shape of target objects on the board by searching a database for bare board information when the measuring object is not set to the normal inspection mode or by performing bare board teaching when the board is supplied from a supplier having not the bare board information, and thereby can improve a productivity of electric circuit boards.
Also, according to the present invention, it is to improve a measurement quality of a 3D shape by measuring the 3D shape while maintaining a brightness of an illumination source, which is applied to measure the 3D shape, to be regular for each operation.
Although a few exemplary embodiments of the present invention have been shown and described, the present invention is not limited to the described exemplary embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method of measuring a 3 dimensional (3D) image, the method comprising:

measuring a brightness of a first illumination source by controlling, by a central control unit, a module control unit and an image acquisition unit;

measuring a phase-to-height conversion factor by controlling, by the central control unit, the module control unit and the image acquisition unit when the brightness of the first illumination source is measured;

determining by the central control unit whether the measurement is performed in a normal inspection mode when the brightness of the first illumination source and the phase-to-height conversion factor are measured;

measuring a 3D shape of target objects on a board according to the normal inspection mode by controlling, by the central control unit, the module control unit and the image acquisition unit when it is the normal inspection mode as a result of the determination;

searching a database and determining, by the central control unit, whether bare board information about the board is included in the database when it is not the normal inspection mode but teaching-based inspection mode as a result of the determination;

performing bare board teaching by controlling, by the central control unit, the module control unit and the image acquisition unit when the bare board information is excluded in the database;

measuring the 3D shape of target objects on the board according to a teaching-based inspection mode by controlling, by the central control unit, the module control unit and the image acquisition unit when the bare board information is included in the database or when bare board teaching information is generated in the performing of the bare board teaching; and

analyzing by the central control unit whether the board is normal or abnormal by using information about the measured 3D shape of target objects on the board when the 3D shape of target objects is measured according to the normal inspection mode and the teaching-based inspection mode.