US20030068078A1 - Automatic filter changer for use on surface mounter inspection camera - Google Patents
Automatic filter changer for use on surface mounter inspection camera Download PDFInfo
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- US20030068078A1 US20030068078A1 US10/024,788 US2478801A US2003068078A1 US 20030068078 A1 US20030068078 A1 US 20030068078A1 US 2478801 A US2478801 A US 2478801A US 2003068078 A1 US2003068078 A1 US 2003068078A1
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- Prior art keywords
- item
- circuit board
- filter
- image
- physical features
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K13/00—Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
- H05K13/08—Monitoring manufacture of assemblages
- H05K13/081—Integration of optical monitoring devices in assembly lines; Processes using optical monitoring devices specially adapted for controlling devices or machines in assembly lines
- H05K13/0812—Integration of optical monitoring devices in assembly lines; Processes using optical monitoring devices specially adapted for controlling devices or machines in assembly lines the monitoring devices being integrated in the mounting machine, e.g. for monitoring components, leads, component placement
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/956—Inspecting patterns on the surface of objects
Definitions
- the invention relates to visualization of printed circuit boards and parts presenting characteristic visualization problems.
- the invention is particularly, but not exclusively, useful for recognizing by computer vision physical features of any of several types of printed circuit boards or electronic parts, where each type of board or part presents a different characteristic visualization problem.
- Automated printed circuit board assembly equipment such as the Automated Component Mounter from Assembléon, utilize computer vision systems to inspect and accurately place printed circuit boards and parts to be mounted on those boards.
- the inspection of these items typically requires visualizing an item, recognizing the physical features of the item and analyzing the physical characteristics of the physical features.
- An empty printed circuit board or card is typically picked out of a storage location and computer vision equipment, including a camera and frontal lighting, is employed by the assembly machine to inspect the physical features on the board. Certain of these physical features are called fiducials, which are provided to precisely register the parts that will be installed on the board. Other such physical features on the circuit board are solder paste contact pads. If the inspected board is not rejected, the assembly machine then places it into position to receive parts for mounting.
- Each part to be mounted is then picked out of a storage location and computer vision equipment, again including a camera and frontal lighting, is employed by the assembly machine to inspect the part. If the part is not rejected, the assembly machine then steers the placement of the part with proper registration to its mounting position on the board or card.
- CCD charge coupled device
- aspects of the invention may be found in a method and apparatus in which a filter is automatically deployed when inspecting circuit boards and parts of a certain type.
- the filter corrects characteristic problems encountered when visualizing the physical features of items of that type.
- the contrast in a image between silver fiducials and a light colored printed circuit board, or between silver contacts and a light colored part may be improved by linearly polarizing the illumination of the circuit board and imaging the board or part through a linear polarizing filter oriented in a different direction than the illumination filter.
- the contrast between contacts of one color and a background of another color in an image of a part may be improved by imaging the part through a color filter.
- the glare in an image of a circuit board or part may be reduced by imaging the board or part through a circular polarizing filter.
- the effect of reflected infrared radiation on a CCD camera may be reduced in an image of a circuit board or part by imaging the board or part through a filter rejecting infrared.
- an aspect of the invention may be found in the following method for visualizing an item having physical features on a background.
- the item is illuminated with electromagnetic radiation, using an illumination source.
- An image is formed of the electromagnetic radiation reflected from the item, which image has characteristic defects depending on the type of item being visualized.
- the reflected electromagnetic radiation is automatically filtered to remove the characteristic defects from the image, thereby improving the contrast between the physical features and the background in the filtered image.
- circuit board or part may be recognized in the filtered image for the purpose of inspection.
- FIG. 1 A block diagram illustrating an exemplary computing environment in accordance with the present disclosure.
- FIG. 1 A block diagram illustrating an exemplary computing environment in accordance with the present disclosure.
- FIG. 1 A block diagram illustrating an exemplary computing environment in accordance with the present disclosure.
- the filter is moved linearly into position.
- Another aspect of the invention may be found in a circuit board or card on which is surface mounted a part that has been recognized in accordance with the method. Through use of the method, recognized physical features of the mounted part are placed in registration with contact pads of the board or card.
- FIG. 1 is a schematic elevational cross-section view of visualization, recognition and placement apparatus in accordance with the invention
- FIG. 2 is a top view of illumination and reption parts of FIG. 1, as viewed from the lines 2 - 2 ;
- FIG. 3 is a cross-section view of visualization, recognition, placement and linear filter deployment apparatus in accordance with the invention, with the filter retracted;
- FIG. 4 is a cross-section view with the filter deployed
- FIG. 5 is a cross-section view of another embodiment of the invention, showing a rotational filter deployment apparatus
- FIG. 6 is a top view of the rotational filter deployment apparatus of FIG. 5.
- FIG. 1 of the drawing an embodiment of the present invention for visualization of parts having metallic objects against a dielectric or nonmetallic poorly contrasting background, is explained in conjunction with a conventional computer vision system 10 recognizing a usually two dimensional Ball Grid Array (BGA) 12 of small high melt solder balls 14 carried by a ceramic dielectric substrate 16 .
- BGA Ball Grid Array
- BGA 12 is held by a gripper or manipulator 18 of a pick and place machine (not shown) over an upwardly looking camera 20 of computer vision system 10 .
- the camera 20 forms and provides an electronic image to computer vision system 10 , which system utilizes the electronic image to recognize and inspect the solder balls 14 of the BGA 12 , as to existence, size and spacing. If the BGA 12 passes inspection, the vision system 10 steers the translation and placement of BGA 12 by manipulator 18 on a circuit board or card 22 , with the recognized solder balls 14 of the BGA in registration with contact pads 24 of the board or card 22 .
- the light box 26 is used to provide generally upwardly and inwardly directed polarized illumination I of BGA 12 , in conjunction with a polarization filter 28 in front of the lens 30 of camera 20 , in order to allow for proper visualization by camera 20 , and proper recognition by vision system 10 of solder balls 14 .
- a preferred embodiment of light box 26 has a central aperture 32 through which camera 20 looks upward via polarization filter 28 , and four upwardly and outwardly inclined trapezoidal faces 34 , 36 , 38 , 40 of a frusto-pyramid, each face forming a separate source of polarized light.
- the faces 34 , 36 , 38 , and 40 comprise polarization filters 40 , 42 , 44 , and 46 over respective milk glass diffuser panels 50 , over LED arrays 52 .
- the downwardly directed component of light reflected from the white or light colored substrate 16 is substantially uniformly distributed in polarization and a substantial amount of light reflected downward from the substrate 16 passes through polarization filter 28 and reaches the lens 30 of camera 20 .
- the solder balls 14 appear substantially black and the substrate 16 appears substantially white, providing good contrast for reliable recognition of solder balls 14 .
- This contrast producing effect is thought to be due to a preservation of polarization in reflection of electromagnetic radiation from shiny metal objects versus a the smearing of polarization in reflection of electromagnetic radiation from dielectric objects.
- a printed circuit board assembly machine will inspect parts of different types during the assembly of a single circuit board. If some of the parts being inspected have a light colored substrate, while others have a black substrate, an additional problem arises. Because the effect of the linear polarizing filter 28 is to cause the solder balls 14 appear substantially black in the electronic image formed by camera 20 , the solder balls may not be easily recognized on parts having a black substrate, when viewed through such a filter. In this situation, it is desirable to deploy the filter 28 in front of the lens 30 of camera 20 when visualizing parts with a white substrate, and retract the filter when visualizing parts with a black substrate.
- circuit board assembly machine handles printed circuit boards or cards.
- Some circuit boards are manufactured with a fiberglass substrate, which is typically green in color. Such a substrate provides good contrast with the silver or gold colored fiducials used to register the parts installed on the circuit board.
- other circuit boards or cards handled by the same assembly machine may have a white, or other light colored, ceramic substrate, which provides poor contrast with the metallic fiducials.
- the technique described above for deploying a filter when appropriate to achieve reliable recognition of solder balls on parts having either light colored or dark colored substrates can also be used to reliably recognize metallic fiducials on either light colored or dark colored printed circuit boards and cards.
- the control system of a circuit board assembly machine typically utilizes a specification file for each type of item (printed circuit board, card or part) it handles.
- This file contains information on the characteristics of each type of item. Information from that file, such as the number and location of physical features (fiducials and contact pads on boards and cards, or contacts on parts), is provided to the computer vision system for the inspection process.
- the specification file would also contain information indicating whether a filter should be used when inspecting an item of that type and, for the embodiment shown in FIG. 5, specifying which type of filter is to be used.
- FIG. 3 of the drawing an embodiment of the invention employing a linear filter deployment apparatus 60 is shown with the filter retracted.
- a filter 61 is attached by linkage 64 to linear actuator 65 .
- the linear actuator 65 When energized by the circuit board assembly machine control system, the linear actuator 65 will adopt the configuration shown, with the filter retracted from the optical axis of the camera 20 .
- the linear actuator 65 When de-energized by the control system, the linear actuator 65 will adopt the configuration shown in FIG. 4 of the drawing, with the linkage extended and the filter 61 deployed in front of the lens 30 of camera 20 .
- the action of the actuator 65 will be the opposite of that described above: when the actuator 65 is energized, the filter 61 will be deployed and when the actuator 65 is de-energized, the filter 61 will be retracted. While the above description discusses the use of a linear actuator to deploy filter 61 , it should be understood that a solenoid could also be employed in an embodiment of the invention.
- Filter 61 in FIGS. 3 and 4 could be the linear polarization filter 28 shown in FIG. 1, employed in combination with linearly polarized illumination, as described above, to correct the visualization problem associated with metallic physical features on a light colored background.
- filter 61 could be one of several other types of filter chosen to correct other characteristic problems, as will now be described. These other types of filters can be used to equal effectiveness with polarized or non-polarized illumination.
- filter 61 could be chosen to be a red color filter. Such a filter would pass the red light reflecting from the red physical features while blocking the green light reflecting from the background, causing the physical features to appear substantially white and the background to appear substantially black in the image from a monochrome camera.
- CCD charge coupled device
- items that are especially reflective in the infrared spectrum may present a different characteristic visualization problem.
- a CCD is very sensitive to radiation in the infrared spectrum
- the electronic image of such an item may be washed out, with both the physical features and the background of the item appearing as light gray objects in the image, preventing the computer vision system from being able to recognize the physical features on the item.
- filter 61 could be chosen to be an infrared filter, which blocks infrared radiation and passes visible light. Blocking the infrared radiation would allow the CCD to form an electronic image only from the visible light reflected from the item, resulting in better contrast between the physical features and background of the item in the filtered image.
- filter 61 could be chosen to be a circular polarizing filter. Such a filter restricts the rotation component of the illumination reflected from the item, thereby reducing glare from the item and allowing correct recognition of the physical features on the item.
- FIG. 5 of the drawing An embodiment of the invention allowing one of several filters to be deployed is illustrated in FIG. 5 of the drawing.
- a rotational filter deployment apparatus 70 is shown, which is a filter wheel 75 mounted on the shaft of stepper motor 76 . Also visible in FIG. 5 are filters 61 and 63 mounted on the filter wheel 75 in registration with apertures 72 and 74 .
- stepper motor 76 In response to signals from the assembly machine control system, stepper motor 76 will rotate to a specified position, thereby deploying the appropriate filter for the part being visualized.
- the rotational filter deployment apparatus 70 is shown in more detail in FIG. 6.
- Filter wheel 75 can be seen to have, in this embodiment of the invention, four apertures 71 , 72 , 73 , and 74 .
- Apertures 72 , 73 , and 74 are covered by filters 61 , 62 , and 63 , respectively, while aperture 71 is not covered with a filter.
- the hub of filter wheel 75 is mounted to the shaft of stepper motor 76 .
- Lens 30 is seen through aperture 74 .
- motor 76 is described above as a stepper motor, it should be understood that servo motors could also be used in an embodiment of the invention to position filter wheel 75 in response to signals from the assembly machine control system.
- FIGS. 3, 4 and 5 show embodiments of the invention being used for visualization of a BGA package, it should be appreciated that the techniques of the invention can be used to improve visualization of other types of packages and of printed circuit boards and cards.
Abstract
Description
- This application is a continuation-in-part of prior co-pending application U.S. Ser. No. 09/970,960, filed Oct. 4, 2001.
- The invention relates to visualization of printed circuit boards and parts presenting characteristic visualization problems. The invention is particularly, but not exclusively, useful for recognizing by computer vision physical features of any of several types of printed circuit boards or electronic parts, where each type of board or part presents a different characteristic visualization problem.
- Automated printed circuit board assembly equipment, such as the Automated Component Mounter from Assembléon, utilize computer vision systems to inspect and accurately place printed circuit boards and parts to be mounted on those boards. The inspection of these items typically requires visualizing an item, recognizing the physical features of the item and analyzing the physical characteristics of the physical features.
- An empty printed circuit board or card is typically picked out of a storage location and computer vision equipment, including a camera and frontal lighting, is employed by the assembly machine to inspect the physical features on the board. Certain of these physical features are called fiducials, which are provided to precisely register the parts that will be installed on the board. Other such physical features on the circuit board are solder paste contact pads. If the inspected board is not rejected, the assembly machine then places it into position to receive parts for mounting.
- Each part to be mounted is then picked out of a storage location and computer vision equipment, again including a camera and frontal lighting, is employed by the assembly machine to inspect the part. If the part is not rejected, the assembly machine then steers the placement of the part with proper registration to its mounting position on the board or card.
- Characteristic problems can arise, however, when the computer vision system attempts to inspect certain types of circuit boards, cards or parts. Some boards or cards are made of a light colored ceramic material and have gold or silver fiducials or solder paste contact pads. These colors do not provide sufficient visual contrast for current computer vision systems to reliably recognize the fiducials or contact pads.
- A similar problem is encountered with parts that have silver or gold metallic contacts on a white or light colored ceramic background, preventing the contacts from being reliably recognized.
- Other parts have contacts of one color on a background of another color, which colors, when imaged by a monochrome camera, lack sufficient contrast to permit reliable recognition of the contacts.
- Another characteristic problem encountered with certain types of parts is glare from the contacts and the background, again preventing reliable recognition of the contacts.
- Yet another problem arises because the charge coupled device (CCD) cameras typically used in computer vision systems are extremely sensitive to infrared. As a result, images of parts that are especially reflective in the infrared spectrum are washed out and difficult to recognize reliably.
- The predecessor of the present application teaches an inventive technique for recognizing the physical features of parts having metallic contacts on a light colored background. However, a printed circuit board assembly machine often must handle, in turn, a mixture of circuit boards and parts, each exhibiting a different one or more of the recognition problems described above. Currently, there are no techniques in use in printed circuit board assembly machines that overcome the variety of recognition problems thereby encountered.
- In a printed circuit board assembly machine handling several types of circuit boards and parts, aspects of the invention may be found in a method and apparatus in which a filter is automatically deployed when inspecting circuit boards and parts of a certain type. The filter corrects characteristic problems encountered when visualizing the physical features of items of that type.
- The contrast in a image between silver fiducials and a light colored printed circuit board, or between silver contacts and a light colored part, may be improved by linearly polarizing the illumination of the circuit board and imaging the board or part through a linear polarizing filter oriented in a different direction than the illumination filter.
- The contrast between contacts of one color and a background of another color in an image of a part may be improved by imaging the part through a color filter.
- The glare in an image of a circuit board or part may be reduced by imaging the board or part through a circular polarizing filter.
- The effect of reflected infrared radiation on a CCD camera may be reduced in an image of a circuit board or part by imaging the board or part through a filter rejecting infrared.
- More specifically, an aspect of the invention may be found in the following method for visualizing an item having physical features on a background. The item is illuminated with electromagnetic radiation, using an illumination source. An image is formed of the electromagnetic radiation reflected from the item, which image has characteristic defects depending on the type of item being visualized. The reflected electromagnetic radiation is automatically filtered to remove the characteristic defects from the image, thereby improving the contrast between the physical features and the background in the filtered image.
- The physical features of the circuit board or part may be recognized in the filtered image for the purpose of inspection.
- Further aspect of the invention may be found in an apparatus for visualizing an item having physical features on a background. One or more sources illuminate the item with electromagnetic radiation. An image forming device forms an image of electromagnetic radiation reflected from the item, which image has a characteristic defect depending on the type of item being visualized. An actuator positions a filter such that the image is formed of electromagnetic radiation passing through the filter, thereby removing the characteristic defect from the image and improving the contrast between the physical features and the background in the image.
- In one exemplary embodiment of the invention the filter is moved linearly into position.
- In another exemplary embodiment of the invention several available filters are mounted on a wheel and rotated into position.
- Another aspect of the invention may be found in a circuit board or card on which is surface mounted a part that has been recognized in accordance with the method. Through use of the method, recognized physical features of the mounted part are placed in registration with contact pads of the board or card.
- Other aspects of the invention will become apparent upon perusal of the following detailed description when taken in conjunction with the appended drawing, wherein:
- FIG. 1 is a schematic elevational cross-section view of visualization, recognition and placement apparatus in accordance with the invention;
- FIG. 2 is a top view of illumination and reption parts of FIG. 1, as viewed from the lines2-2;
- FIG. 3 is a cross-section view of visualization, recognition, placement and linear filter deployment apparatus in accordance with the invention, with the filter retracted;
- FIG. 4 is a cross-section view with the filter deployed;
- FIG. 5 is a cross-section view of another embodiment of the invention, showing a rotational filter deployment apparatus; and
- FIG. 6 is a top view of the rotational filter deployment apparatus of FIG. 5.
- Referring to FIG. 1 of the drawing, an embodiment of the present invention for visualization of parts having metallic objects against a dielectric or nonmetallic poorly contrasting background, is explained in conjunction with a conventional
computer vision system 10 recognizing a usually two dimensional Ball Grid Array (BGA) 12 of small highmelt solder balls 14 carried by a ceramicdielectric substrate 16. - BGA12 is held by a gripper or
manipulator 18 of a pick and place machine (not shown) over an upwardly lookingcamera 20 ofcomputer vision system 10. Thecamera 20 forms and provides an electronic image tocomputer vision system 10, which system utilizes the electronic image to recognize and inspect thesolder balls 14 of theBGA 12, as to existence, size and spacing. If theBGA 12 passes inspection, thevision system 10 steers the translation and placement ofBGA 12 bymanipulator 18 on a circuit board orcard 22, with the recognizedsolder balls 14 of the BGA in registration withcontact pads 24 of the board orcard 22. - As is conventional, prior to placement of the
BGA 12 and other surface mount components on the circuit board orcard 22 thecontact pads 24 are coated with a eutectic solder paste, and after the placement of theBGA 12 and other surface mount components on circuit board orcard 22, heat is applied to card with placed BGA and other components to fuse the solder paste into fillets (not shown) firmly surface mounting the BGA to the circuit board or card. - In the poorest contrast situation when the
solder balls 14 are silver colored and thesubstrate 16 is white or light colored, thelight box 26 is used to provide generally upwardly and inwardly directed polarized illumination I ofBGA 12, in conjunction with apolarization filter 28 in front of thelens 30 ofcamera 20, in order to allow for proper visualization bycamera 20, and proper recognition byvision system 10 ofsolder balls 14. - As shown in FIG. 2, a preferred embodiment of
light box 26 has acentral aperture 32 through whichcamera 20 looks upward viapolarization filter 28, and four upwardly and outwardly inclinedtrapezoidal faces faces polarization filters glass diffuser panels 50, overLED arrays 52. - With the direction of linear polarization passed by
polarization filter 28 taken as 0°,polarization filters polarization filters solder balls 14 has a polarization at 90°, which is, or is nearly, orthogonal with the polarization direction that would be passed bypolarization filter 28. Therefore no light reflected bysolder balls 14 reach thelens 30 ofcamera 20. - On the other hand, the downwardly directed component of light reflected from the white or light
colored substrate 16 is substantially uniformly distributed in polarization and a substantial amount of light reflected downward from thesubstrate 16 passes throughpolarization filter 28 and reaches thelens 30 ofcamera 20. As a result, in the electronic image formed bycamera 20, thesolder balls 14 appear substantially black and thesubstrate 16 appears substantially white, providing good contrast for reliable recognition ofsolder balls 14. This contrast producing effect is thought to be due to a preservation of polarization in reflection of electromagnetic radiation from shiny metal objects versus a the smearing of polarization in reflection of electromagnetic radiation from dielectric objects. - A printed circuit board assembly machine will inspect parts of different types during the assembly of a single circuit board. If some of the parts being inspected have a light colored substrate, while others have a black substrate, an additional problem arises. Because the effect of the linear
polarizing filter 28 is to cause thesolder balls 14 appear substantially black in the electronic image formed bycamera 20, the solder balls may not be easily recognized on parts having a black substrate, when viewed through such a filter. In this situation, it is desirable to deploy thefilter 28 in front of thelens 30 ofcamera 20 when visualizing parts with a white substrate, and retract the filter when visualizing parts with a black substrate. - A similar problem arises when the circuit board assembly machine handles printed circuit boards or cards. Some circuit boards are manufactured with a fiberglass substrate, which is typically green in color. Such a substrate provides good contrast with the silver or gold colored fiducials used to register the parts installed on the circuit board. However, other circuit boards or cards handled by the same assembly machine may have a white, or other light colored, ceramic substrate, which provides poor contrast with the metallic fiducials. The technique described above for deploying a filter when appropriate to achieve reliable recognition of solder balls on parts having either light colored or dark colored substrates can also be used to reliably recognize metallic fiducials on either light colored or dark colored printed circuit boards and cards.
- The control system of a circuit board assembly machine typically utilizes a specification file for each type of item (printed circuit board, card or part) it handles. This file contains information on the characteristics of each type of item. Information from that file, such as the number and location of physical features (fiducials and contact pads on boards and cards, or contacts on parts), is provided to the computer vision system for the inspection process. In an assembly machine employing the techniques of the invention, the specification file would also contain information indicating whether a filter should be used when inspecting an item of that type and, for the embodiment shown in FIG. 5, specifying which type of filter is to be used.
- Referring now to FIG. 3 of the drawing, an embodiment of the invention employing a linear filter deployment apparatus60 is shown with the filter retracted. A
filter 61 is attached bylinkage 64 tolinear actuator 65. When energized by the circuit board assembly machine control system, thelinear actuator 65 will adopt the configuration shown, with the filter retracted from the optical axis of thecamera 20. When de-energized by the control system, thelinear actuator 65 will adopt the configuration shown in FIG. 4 of the drawing, with the linkage extended and thefilter 61 deployed in front of thelens 30 ofcamera 20. - For some types of linear actuators, the action of the
actuator 65 will be the opposite of that described above: when theactuator 65 is energized, thefilter 61 will be deployed and when theactuator 65 is de-energized, thefilter 61 will be retracted. While the above description discusses the use of a linear actuator to deployfilter 61, it should be understood that a solenoid could also be employed in an embodiment of the invention. -
Filter 61 in FIGS. 3 and 4 could be thelinear polarization filter 28 shown in FIG. 1, employed in combination with linearly polarized illumination, as described above, to correct the visualization problem associated with metallic physical features on a light colored background. Or, filter 61 could be one of several other types of filter chosen to correct other characteristic problems, as will now be described. These other types of filters can be used to equal effectiveness with polarized or non-polarized illumination. - If the item being visualized has, for example, red physical features on a green background,
filter 61 could be chosen to be a red color filter. Such a filter would pass the red light reflecting from the red physical features while blocking the green light reflecting from the background, causing the physical features to appear substantially white and the background to appear substantially black in the image from a monochrome camera. - If
camera 20 employs a charge coupled device (CCD) to form the electronic image, items that are especially reflective in the infrared spectrum may present a different characteristic visualization problem. Because a CCD is very sensitive to radiation in the infrared spectrum, the electronic image of such an item may be washed out, with both the physical features and the background of the item appearing as light gray objects in the image, preventing the computer vision system from being able to recognize the physical features on the item. For this type of item, filter 61 could be chosen to be an infrared filter, which blocks infrared radiation and passes visible light. Blocking the infrared radiation would allow the CCD to form an electronic image only from the visible light reflected from the item, resulting in better contrast between the physical features and background of the item in the filtered image. - If glare is characteristically encountered when visualizing certain items, the image produced by
camera 20 will again be washed out. In these situations, filter 61 could be chosen to be a circular polarizing filter. Such a filter restricts the rotation component of the illumination reflected from the item, thereby reducing glare from the item and allowing correct recognition of the physical features on the item. - While the preceding discussion has described recognizing contacts on electronic parts or fiducials and contact pads on printed circuit boards and cards, it should be understood that the physical features being recognized on other items may not be contacts or fiducials. For example, when a lens is to be mounted over a light emitting diode, the lens will be inspected for mounting features that allow it to be attached to the circuit board or card. Similarly, a circuit board or card may be inspected for the presence and accurate placement of thermoset adhesive glue dots, which serve to mount parts that are not soldered to the board.
- If the items being handled by a circuit board assembly machine each exhibit a different characteristic problem, then one of several different filters must be deployed, depending on the item being inspected, to allow reliable recognition of the physical features of that item. An embodiment of the invention allowing one of several filters to be deployed is illustrated in FIG. 5 of the drawing. A rotational
filter deployment apparatus 70 is shown, which is afilter wheel 75 mounted on the shaft ofstepper motor 76. Also visible in FIG. 5 arefilters filter wheel 75 in registration withapertures stepper motor 76 will rotate to a specified position, thereby deploying the appropriate filter for the part being visualized. - The rotational
filter deployment apparatus 70 is shown in more detail in FIG. 6.Filter wheel 75 can be seen to have, in this embodiment of the invention, fourapertures Apertures filters aperture 71 is not covered with a filter. The hub offilter wheel 75 is mounted to the shaft ofstepper motor 76.Lens 30 is seen throughaperture 74. - While
motor 76 is described above as a stepper motor, it should be understood that servo motors could also be used in an embodiment of the invention to positionfilter wheel 75 in response to signals from the assembly machine control system. - While FIGS. 3, 4 and5 show embodiments of the invention being used for visualization of a BGA package, it should be appreciated that the techniques of the invention can be used to improve visualization of other types of packages and of printed circuit boards and cards.
- While the embodiments discussed above show only a single filter deployment apparatus in use, it should be understood that, in yet another embodiment of the invention, multiple filters could be deployed together by multiple filter deployment apparatuses, to improve visualization of items that present multiple characteristic problems.
- It should now be appreciated that the objects of the invention have been satisfied. While the invention has been described in particular detail, it should also be appreciated that numerous modifications are possible within the intended spirit and scope of the invention. In interpreting the appended claims it should be understood that:
- a) the word “comprising” does not exclude the presence of other elements or steps than those listed in a claim;
- b) the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.
- c) any reference signs in the claims do not limit their scope; and
- d) several “means” may be represented by the same item of hardware or software implemented structure or function.
Claims (18)
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/024,788 US20030068078A1 (en) | 2001-10-04 | 2001-12-19 | Automatic filter changer for use on surface mounter inspection camera |
PCT/IB2002/004046 WO2003032705A1 (en) | 2001-10-04 | 2002-09-30 | Automatic filter changer for use on surface mounter inspection camera |
JP2003535520A JP2005505942A (en) | 2001-10-04 | 2002-09-30 | Automatic filter changer for use on surface mounter inspection cameras. |
EP02772667A EP1438883A1 (en) | 2001-10-04 | 2002-09-30 | Automatic filter changer for use on surface mounter inspection camera |
CNA02819389XA CN1561659A (en) | 2001-10-04 | 2002-09-30 | Automatic filter changer for use on surface mounter inspection camera |
KR10-2004-7004978A KR20040062558A (en) | 2001-10-04 | 2002-09-30 | Automatic filter changer for use on surface mounter inspection camera |
TW91122831A TW545089B (en) | 2001-12-19 | 2002-10-03 | Automatic filter changer for use on surface mounter inspection camera |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/970,960 US6765185B2 (en) | 2001-10-04 | 2001-10-04 | Computer vision recognition of metallic objects against a poorly contrasting background |
US10/024,788 US20030068078A1 (en) | 2001-10-04 | 2001-12-19 | Automatic filter changer for use on surface mounter inspection camera |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/970,960 Continuation-In-Part US6765185B2 (en) | 2001-10-04 | 2001-10-04 | Computer vision recognition of metallic objects against a poorly contrasting background |
Publications (1)
Publication Number | Publication Date |
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US20030068078A1 true US20030068078A1 (en) | 2003-04-10 |
Family
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Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US09/970,960 Expired - Fee Related US6765185B2 (en) | 2001-10-04 | 2001-10-04 | Computer vision recognition of metallic objects against a poorly contrasting background |
US10/024,788 Abandoned US20030068078A1 (en) | 2001-10-04 | 2001-12-19 | Automatic filter changer for use on surface mounter inspection camera |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
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US09/970,960 Expired - Fee Related US6765185B2 (en) | 2001-10-04 | 2001-10-04 | Computer vision recognition of metallic objects against a poorly contrasting background |
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US (2) | US6765185B2 (en) |
EP (1) | EP1438570A1 (en) |
JP (1) | JP2005504986A (en) |
KR (2) | KR20040053152A (en) |
CN (1) | CN1564937A (en) |
WO (1) | WO2003031957A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110025843A1 (en) * | 2009-07-31 | 2011-02-03 | Mesa Imaging Ag | Time of Flight Camera with Rectangular Field of Illumination |
US9128036B2 (en) | 2011-03-21 | 2015-09-08 | Federal-Mogul Corporation | Multi-spectral imaging system and method of surface inspection therewith |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050018403A1 (en) * | 2003-06-25 | 2005-01-27 | Foo Chong Seng | BGA ball vision enhancement |
US8223200B1 (en) | 2009-06-09 | 2012-07-17 | Hormel Foods Corporation | Package vision evaluation system |
US9627306B2 (en) | 2012-02-15 | 2017-04-18 | Cypress Semiconductor Corporation | Ball grid structure |
KR20150090699A (en) * | 2014-01-29 | 2015-08-06 | 한화테크윈 주식회사 | Apparatus for inspecting component |
CN106354038A (en) * | 2016-09-06 | 2017-01-25 | 江苏艾科瑞思封装自动化设备有限公司 | Intelligent control system of micro-assembly equipment |
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2001
- 2001-10-04 US US09/970,960 patent/US6765185B2/en not_active Expired - Fee Related
- 2001-12-19 US US10/024,788 patent/US20030068078A1/en not_active Abandoned
-
2002
- 2002-09-25 KR KR10-2004-7005065A patent/KR20040053152A/en not_active Application Discontinuation
- 2002-09-25 WO PCT/IB2002/003987 patent/WO2003031957A1/en not_active Application Discontinuation
- 2002-09-25 JP JP2003534890A patent/JP2005504986A/en not_active Withdrawn
- 2002-09-25 CN CN02819762.3A patent/CN1564937A/en active Pending
- 2002-09-25 EP EP02800681A patent/EP1438570A1/en not_active Withdrawn
- 2002-09-30 KR KR10-2004-7004978A patent/KR20040062558A/en not_active Application Discontinuation
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US3713741A (en) * | 1972-01-03 | 1973-01-30 | Western Electric Co | Methods of and apparatus for locating solder faults |
US5044072A (en) * | 1990-04-13 | 1991-09-03 | Air-Vac Engineering Company, Inc. | Vision system apparatus and method for component/pad alignment |
US5249356A (en) * | 1991-03-20 | 1993-10-05 | Matsushita Electric Industrial Co., Ltd. | Method and apparatus for mounting electronic component |
US5524152A (en) * | 1992-03-12 | 1996-06-04 | Beltronics, Inc. | Method of and apparatus for object or surface inspection employing multicolor reflection discrimination |
US6028303A (en) * | 1996-11-14 | 2000-02-22 | Nikon Corporation | Polarizing filter control mechanism to reduce reflected light |
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US20110025843A1 (en) * | 2009-07-31 | 2011-02-03 | Mesa Imaging Ag | Time of Flight Camera with Rectangular Field of Illumination |
US8803967B2 (en) * | 2009-07-31 | 2014-08-12 | Mesa Imaging Ag | Time of flight camera with rectangular field of illumination |
US9344705B2 (en) | 2009-07-31 | 2016-05-17 | Heptagon Micro Optics Pte. Ltd. | Time of flight camera with rectangular field of illumination |
US9128036B2 (en) | 2011-03-21 | 2015-09-08 | Federal-Mogul Corporation | Multi-spectral imaging system and method of surface inspection therewith |
Also Published As
Publication number | Publication date |
---|---|
KR20040053152A (en) | 2004-06-23 |
KR20040062558A (en) | 2004-07-07 |
EP1438570A1 (en) | 2004-07-21 |
WO2003031957A1 (en) | 2003-04-17 |
JP2005504986A (en) | 2005-02-17 |
CN1564937A (en) | 2005-01-12 |
US6765185B2 (en) | 2004-07-20 |
US20030066952A1 (en) | 2003-04-10 |
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Legal Events
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Owner name: ASSEMBLEON N.V. COMPANY, NETHERLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KONINKLIJKE PHILIPS ELETRONICS N.V. COMPANY;REEL/FRAME:012878/0827 Effective date: 20020305 |
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