WO2014184149A1 - Workpiece handling system and method - Google Patents

Workpiece handling system and method Download PDF

Info

Publication number
WO2014184149A1
WO2014184149A1 PCT/EP2014/059670 EP2014059670W WO2014184149A1 WO 2014184149 A1 WO2014184149 A1 WO 2014184149A1 EP 2014059670 W EP2014059670 W EP 2014059670W WO 2014184149 A1 WO2014184149 A1 WO 2014184149A1
Authority
WO
WIPO (PCT)
Prior art keywords
belt
platen
light sources
workpiece
rollers
Prior art date
Application number
PCT/EP2014/059670
Other languages
French (fr)
Inventor
Jeffrey Richard Willshere
Diming YANG
Michael John Rogers
Original Assignee
Dtg International Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dtg International Gmbh filed Critical Dtg International Gmbh
Publication of WO2014184149A1 publication Critical patent/WO2014184149A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q7/00—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting
    • B23Q7/14—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines
    • B23Q7/1426—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines with work holders not rigidly fixed to the transport devices
    • B23Q7/1447—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines with work holders not rigidly fixed to the transport devices using endless conveyors
    • B23Q7/1452—Arrangements for handling work specially combined with or arranged in, or specially adapted for use in connection with, machine tools, e.g. for conveying, loading, positioning, discharging, sorting co-ordinated in production lines with work holders not rigidly fixed to the transport devices using endless conveyors comprising load-supporting surfaces
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67703—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations between different workstations
    • H01L21/67706—Mechanical details, e.g. roller, belt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q16/00—Equipment for precise positioning of tool or work into particular locations not otherwise provided for
    • B23Q16/02—Indexing equipment
    • B23Q16/12—Indexing equipment using optics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/24—Arrangements for observing, indicating or measuring on machine tools using optics or electromagnetic waves
    • B23Q17/2433—Detection of presence or absence
    • B23Q17/2447—Detection of presence or absence of a workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
    • B65G47/00—Article or material-handling devices associated with conveyors; Methods employing such devices
    • B65G47/74—Feeding, transfer, or discharging devices of particular kinds or types
    • B65G47/84—Star-shaped wheels or devices having endless travelling belts or chains, the wheels or devices being equipped with article-engaging elements
    • B65G47/841—Devices having endless travelling belts or chains equipped with article-engaging elements
    • B65G47/843—Devices having endless travelling belts or chains equipped with article-engaging elements the article-engaging elements being suction or magnetic means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/10—Segmentation; Edge detection
    • G06T7/13—Edge detection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/68—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for positioning, orientation or alignment
    • H01L21/681—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for positioning, orientation or alignment using optical controlling means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6838—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping with gripping and holding devices using a vacuum; Bernoulli devices

Definitions

  • the present invention relates to a workpiece handling system for and a method of handling workpieces, typically substrates, for example, solar or fuel cell wafers.
  • the present invention provides a workpiece handling system for handling workpieces, comprising : a workpiece support unit which is operative to support a workpiece in a processing operation, wherein the workpiece support unit comprises a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the body to transfer workpieces thereon to and from the platen, and a drive arrangement which drives the belt to transfer workpieces; and an imaging unit for imaging a supported workpiece, wherein the imaging unit comprises a plurality of discrete light sources which are arranged to illuminate respective edge features of the supported workpiece through the belt, and a plurality of detectors arranged in correspondence to the respective light sources to detect transmitted illumination from respective ones of the light sources, whereby images of each of the respective edge features can be acquired.
  • the body of the platen includes an air-permeable section which is operably connected to a vacuum or reduced pressure source, such that, on application of a vacuum or reduced pressure to the air-permeable section, the supported workpiece is drawn to the platen and maintained in fixed relation to the platen.
  • the air-permeable section comprises a porous component, optionally a sintered component.
  • the air-permeable section comprises an apertured component including an array of through bores therein.
  • the belt is an endless belt, a section of which is driven over the platen.
  • the belt is optically transmissive of light from the light source.
  • the belt is formed of silicone.
  • the belt includes a layer of silicone on an outer surface thereof.
  • the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
  • the belt includes a support web, optionally a woven web.
  • the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
  • the belt includes a plurality of through apertures arranged in spaced relation thereover.
  • the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
  • the apertures are more closely spaced in an intermediate region of a width of the belt.
  • the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel, and a third group of apertures which is located intermediate the first and second groups of apertures.
  • first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
  • the third group of apertures extends across a central region which is about one half of the width of the belt.
  • the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
  • the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
  • the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, such that rotation of the at least one of the rollers causes rotation of the belt, and a drive which is operable to drive the at least one of the rollers.
  • one of the rollers is driven, and the other of the rollers is free to follow the first roller.
  • the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
  • the belt aligner comprises a sensor which acts to detect one edge of the belt, an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and a controller which is operative to cause the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
  • controller is operative to switch the direction of tracking of the belt when the edge of the belt is no longer visible to the sensor.
  • the light sources provide light in the visible spectrum.
  • the light has a wavelength of from about 640 nm to about 680 nm.
  • the light sources provide diffuse light.
  • the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and thereby illuminate edge features of the respective one of the workpieces.
  • the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
  • the imaging unit comprises a plurality of cameras, which each support a plurality of detectors and are movably disposed relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources.
  • the cameras are moved in unison.
  • the cameras each support two detectors for detecting edge features at two spaced locations.
  • the cameras are disposed to at least one lateral side of the platen.
  • the cameras are disposed to opposite lateral sides of the platen.
  • the cameras are movable longitudinally relative to a direction of travel over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
  • the cameras are pre-aligned to one of the longitudinal positions in dependence upon the kind of workpiece to be handled, and, in movement between the inoperative and operative positions during image acquisition, the cameras are moved only in a single direction laterally to one of the lateral positions.
  • the light sources are mounted within the platen.
  • the light sources are mounted below the platen.
  • the detectors are operative to acquire images simultaneously.
  • the present invention provides a method of handling workpieces, comprising the steps of: providing a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the platen to transfer workpieces thereon to and from the platen, and a drive arrangement for driving the belt; providing an imaging unit comprising a plurality of discrete light sources which are arranged to illuminate respective edge features of a supported workpiece through the belt, and a plurality of detectors which are arranged to detect transmitted illumination from respective ones of the light sources; driving the belt to transfer a workpiece onto the platen; moving the detectors to operative, image acquisition positions in correspondence with respective ones of the light sources; and acquiring images of each of the respective edge features of the supported workpiece.
  • the body of the platen includes an air-permeable section which is operably connected to a vacuum or reduced pressure source, and the method further comprises the step of: applying a vacuum or reduced pressure to the air-permeable section to draw the supported workpiece to the platen and maintain the workpiece in fixed relation to the platen.
  • the air-permeable section comprises a porous component, optionally a sintered component.
  • the air-permeable section comprises an apertured component including an array of through bores therein.
  • the belt is an endless belt, a section of which is driven over the platen.
  • the belt is optically transmissive of light from the light source.
  • the belt is formed of silicone.
  • the belt includes a layer of silicone on an outer surface thereof.
  • the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
  • the belt includes a support web, optionally a woven web.
  • the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
  • the belt includes a plurality of through apertures arranged in spaced relation thereover.
  • the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
  • the apertures are more closely spaced in an intermediate region of a width of the belt.
  • the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel of the belt, and a third group of apertures which is located intermediate the first and second groups of apertures.
  • first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
  • the third group of apertures extends across a central region which is about one half of the width of the belt.
  • the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
  • the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
  • the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, whereby rotation of at least one of the rollers causes rotation of the belt.
  • one of the rollers is driven, and the other of the rollers is free to follow the first roller.
  • the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
  • the belt aligner comprises a sensor which acts to detect one edge of the belt, and an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and the method further comprises the step of: causing the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
  • the direction of tracking of the belt is switched when the edge of the belt is no longer visible to the sensor.
  • the light sources provide light in the visible spectrum.
  • the light has a wavelength of from about 640 nm to about 680 nm.
  • the light sources provide diffuse light.
  • the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and illuminating edge features of the respective one of the respective workpieces.
  • the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
  • the imaging unit comprises a plurality of cameras, which each support a plurality of detectors, and the method further comprises the step of: moving the cameras relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources.
  • the cameras are moved in unison.
  • the cameras each support two detectors for detecting edge features at two spaced locations.
  • the cameras are disposed to at least one lateral side of the platen.
  • the cameras are disposed to opposite lateral sides of the platen. In one embodiment the cameras are movable longitudinally relative to a direction of travel of the belt over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
  • the method further comprises the steps of: pre-aligning the cameras to one of the longitudinal positions in dependence upon the kind of workpiece to be handled; and moving the cameras in only a single direction laterally to one of the lateral positions between the inoperative and operative positions during image acquisition.
  • the light sources are mounted within the platen.
  • the light sources are mounted below the platen.
  • the detectors are operative to acquire images simultaneously.
  • Figure 1 illustrates a perspective view of a workpiece handling system in accordance with a preferred embodiment of the present invention
  • Figure 2 illustrates a plan view of the workpiece handling system of Figure i ;
  • Figure 3 illustrates a plan view of the workpiece handling system of Figure 1, with the transport belt removed;
  • Figure 4 illustrates a longitudinal sectional view (along section I-I in Figure 2) of the workpiece support unit of the workpiece handling system of Figure i ;
  • Figure 5 illustrates a plan view of the transport belt of the workpiece handling system of Figure 1 ;
  • Figure 6 illustrates a side view of the transport belt of Figure 5.
  • Figure 7 illustrates a plan view of the transport belt of Figure 5, laid flat prior to fabrication in endless form.
  • the workpiece handling system comprises a workpiece support unit 3 which is operative to support a workpiece W in a processing operation, an infeed unit 5 for feeding workpieces W in succession to the workpiece support unit 3 for processing and an outfeed unit 7 for feeding workpieces W from the workpiece support unit 3 following processing.
  • the workpiece support unit 3 comprises a platen 9 which supports a workpiece W thereon during a processing operation, here a printing operation.
  • the platen 9 comprises a body 10, here having a substantially planar upper surface, and a belt 12 which extends over the upper surface of the body 10 and is operable to transfer workpieces W to and from the platen 9, here in a transport axis.
  • the body 10 includes an air-permeable section 15 which is operably connected to a vacuum or reduced pressure source, such that, on application of a vacuum or reduced pressure to the air-permeable section 15, a supported workpiece W is drawn thereto and maintained in fixed relation.
  • the air-permeable section 15 comprises a porous component, here formed by sintering.
  • the air-permeable section 15 could comprise an apertured component which includes an array of through bores therein.
  • the platen 9 further comprises a drive arrangement 19 which drives the belt 12 to transfer workpieces W.
  • the belt 12 is an endless belt, a section of which is driven over the upper surface of the platen 9.
  • the belt 12 is formed of silicone, but in other embodiments could include a layer of silicone on an outer surface thereof.
  • the outer surface of the belt 12 has a shore hardness (Shore D) of 40. In preferred embodiments the outer surface of the belt 12 has a shore hardness (Shore D) of from about 30 to about 50.
  • the belt 12 includes a support web, here in the form of a woven web.
  • the belt 12 has a thickness of about 0.7 mm. In preferred embodiments the belt 12 has a thickness of from about 0.2 mm to about 1.5 mm, preferably from about 0.2 mm to about 1.0 mm, more preferably from about 0.4 mm to about 1.0 mm, still more preferably from about 0.5 mm to about 0.9 mm, and yet still more preferably from about 0.6 mm to about 0.8 mm.
  • the belt 12 includes a plurality of through apertures 25, here arranged in spaced relation over a surface thereof, by which a vacuum or reduced pressure is transferred from the platen 9 to a workpiece W when supported thereon, such as to fix the workpiece W to the platen 9 for processing.
  • the apertures 25 have an average diameter of about 1.5 mm. In preferred embodiments the apertures 25 have an average diameter of from about 0.5 mm to about 2.5 mm, and preferably from about 1.0 mm to about 2.0 mm.
  • apertures 25 are more closely spaced in an intermediate region of the belt 12 in the direction of travel.
  • the belt 12 includes first and second groups of apertures 25a, b which are located at edge regions of the belt 12 in the direction of travel, and a third group of apertures 25c which is located intermediate the first and second groups of apertures 25a, b.
  • first and second groups of apertures 25a, b each extend across a region which is about one quarter the width of the belt 12.
  • the third group of apertures 25c extends across a central region which is about one half of the width of the belt 12.
  • the groups of apertures 25a-c are arranged such that the belt 12 includes a plurality of non-apertured regions 27 along the length thereof in the direction of travel. As will be described in more detail hereinbelow, the non-apertured regions 27 are arranged such that no apertures 25 are within the field of view of the detectors 65a, b of the cameras 61, 63.
  • the non-apertured regions 27 have a width, lateral to the direction of travel of the belt 12, of at least about 5 mm, preferably at least about 7 mm, more preferably at least about 10 mm.
  • the belt 12 is sufficiently optically transparent to visible light as to enable transmission of illumination therethrough.
  • the drive arrangement 19 comprises first and second rollers 31, 33 which are disposed adjacent opposite ends of the platen 9 and receive the belt 12 thereon, such that rotation of at least one of the rollers 31, 33 causes rotation of the belt 12, and a drive (not illustrated) which is operable to drive the at least one of the rollers 31, 33.
  • one of the rollers 31, 33 here the first roller 31, is driven, and the other of the rollers 31, 33, here the second roller 33, is freely rotatable to follow the first roller 31.
  • the drive arrangement 19 comprises a belt aligner 41 which maintains the belt 12 at a predefined location on the rollers 31, 33.
  • the belt aligner 41 comprises a sensor 43 which acts to detect one edge of the belt 12, an actuator 45 which acts to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track in a respective one of the directions along a length of the rollers 31, 33, and a controller 47 which is operative to cause the actuator 45 to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track in one direction along a length of the rollers 31, 33, and, when the edge of the belt 12 is no longer visible to the sensor 43, to cause the actuator 45 to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track back in the other direction along a length of the rollers 31, 33, and repeatedly cause the belt 12 to be tracked in the opposite directions in order to maintain the belt 12 at a predefined location.
  • the workpiece handling system further comprises an imaging unit 51 for imaging a workpiece W
  • the imaging unit 51 comprises a plurality of discrete light sources 53a-d, 55a-d which are arranged within the platen 9 for illuminating respective edges of the supported workpiece W.
  • the light sources 53a-d, 55a-d are grouped in correspondence to the size and/or shape of workpieces W to be processed by the workpiece handling system.
  • the groups of light sources 53a-d, 55a-d are arranged such as to illuminate the respective edges of workpieces Wl, W2 of two different sizes, being rectangular and of 125x125 mm and 156x156 mm in size.
  • the light sources 53a-d, 55a-d provide light, here diffuse light, in the visible spectrum.
  • the light is red light having a peak wavelength of 660 nm and a spectral half-width of 20 nm. In preferred embodiments the light has a wavelength of from about 640 nm to about 680 nm.
  • the light sources 53a-d, 55a-d could provide infra-red light, preferably in the near infra-red region.
  • the imaging unit 51 further comprises a plurality of, in this embodiment first and second cameras 61, 63 which are configured to acquire images of the respective edges of a supported workpiece W as illuminated by the respective light sources 53a-d, 55a-d.
  • the cameras 61, 63 each comprise a plurality of detectors 65a, b in correspondence to the respective light sources 53a-d, 55a-d, whereby images of each of the respective edges of the workpiece W can be acquired simultaneously using the cameras 61, 63.
  • the imaging unit 51 further comprises a drive assembly 71 which is operative to move the respective cameras 61, 63 laterally (X) and transversely (Y) relative to the platen 9.
  • the drive assembly 71 comprises first and second drive units 73a, b which each comprise a first actuator 75 which is operable to move the respective camera 61, 63 laterally (X) and a second actuator 77 which is operable to move the respective camera 61, 63 transversely (Y).
  • the cameras 61, 63 can be pre-aligned laterally (X) relative to the platen 9 in dependence upon the kind of workpiece W to be imaged, here positions PI for the first kind of workpiece Wl and positions P2 for the second kind of workpiece W2, whereby, in an image acquisition step, the cameras 61, 63 are simultaneously driven only transversely (Y) relative to the platen 9, in this embodiment in a single operation, and the cameras 61, 63 are aligned with the respective light sources 53a-d, 55a-d in the platen 9.
  • This arrangement is particularly advantageous, in enabling image acquisition from different kinds of workpieces W in a very short cycle time, being determined by the time for the cameras 61, 63 to be simultaneously driven transversely (Y) to the image acquisition positions inboard of the platen 9 and returned to positions laterally outboard of the platen 9.
  • this arrangement in detecting transmitted light, provides for an accurate determination of an edge of the workpiece W, in that the image comprises two regions of marked contrast, being a dark region corresponding to the workpiece W through which light is not transmitted and a light region which corresponds to the transmission of light beyond the edge of the workpiece W. Given this marked contrast, no significant image processing is required to identify that part of the image which corresponds to the edge of the workpiece W, as is typically required from a reflectance measurement.
  • this arrangement allows for the cameras 61, 63 to have a low profile, thereby typically requiring the platen 9 to be separated from processing equipment, in this embodiment a printing screen, by not more than about 15 mm.
  • the spacing between an upper surface of the camera 61, 63 and a lower surface of the printing screen thereabove is not more than about 3 mm and the spacing between a lower surface of the camera 61, 63 and an upper surface of the platen 9, here the surface of the belt 12, is not more than about 5 mm.

Abstract

A workpiece handling system for and method of handling workpieces, the system comprising : a workpiece support unit which is operative to support a workpiece in a processing operation, wherein the workpiece support unit comprises a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the body to transfer workpieces thereon to and from the platen, and a drive arrangement which drives the belt to transfer workpieces; and an imaging unit for imaging a supported workpiece, wherein the imaging unit comprises a plurality of discrete light sources which are arranged to illuminate respective edge features of the supported workpiece through the belt, and a plurality of detectors arranged in correspondence to the respective light sources to detect transmitted illumination from respective ones of the light sources, whereby images of each of the respective edge features can be acquired.

Description

WORKIPECE HANDLING SYSTEM AND METHOD
The present invention relates to a workpiece handling system for and a method of handling workpieces, typically substrates, for example, solar or fuel cell wafers.
In one aspect the present invention provides a workpiece handling system for handling workpieces, comprising : a workpiece support unit which is operative to support a workpiece in a processing operation, wherein the workpiece support unit comprises a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the body to transfer workpieces thereon to and from the platen, and a drive arrangement which drives the belt to transfer workpieces; and an imaging unit for imaging a supported workpiece, wherein the imaging unit comprises a plurality of discrete light sources which are arranged to illuminate respective edge features of the supported workpiece through the belt, and a plurality of detectors arranged in correspondence to the respective light sources to detect transmitted illumination from respective ones of the light sources, whereby images of each of the respective edge features can be acquired.
In one embodiment the body of the platen includes an air-permeable section which is operably connected to a vacuum or reduced pressure source, such that, on application of a vacuum or reduced pressure to the air-permeable section, the supported workpiece is drawn to the platen and maintained in fixed relation to the platen.
In one embodiment the air-permeable section comprises a porous component, optionally a sintered component.
In another embodiment the air-permeable section comprises an apertured component including an array of through bores therein. In one embodiment the belt is an endless belt, a section of which is driven over the platen.
In one embodiment the belt is optically transmissive of light from the light source.
In one embodiment the belt is formed of silicone.
In one embodiment the belt includes a layer of silicone on an outer surface thereof.
In one embodiment the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
In one embodiment the belt includes a support web, optionally a woven web.
In one embodiment the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
In one embodiment the belt includes a plurality of through apertures arranged in spaced relation thereover.
In one embodiment the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
In one embodiment the apertures are more closely spaced in an intermediate region of a width of the belt.
In one embodiment the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel, and a third group of apertures which is located intermediate the first and second groups of apertures.
In one embodiment the first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
In one embodiment the third group of apertures extends across a central region which is about one half of the width of the belt.
In one embodiment the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
In one embodiment the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
In one embodiment the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, such that rotation of the at least one of the rollers causes rotation of the belt, and a drive which is operable to drive the at least one of the rollers.
In one embodiment one of the rollers is driven, and the other of the rollers is free to follow the first roller.
In one embodiment the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
In one embodiment the belt aligner comprises a sensor which acts to detect one edge of the belt, an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and a controller which is operative to cause the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
In one embodiment the controller is operative to switch the direction of tracking of the belt when the edge of the belt is no longer visible to the sensor.
In one embodiment the light sources provide light in the visible spectrum.
In one embodiment the light has a wavelength of from about 640 nm to about 680 nm.
In one embodiment the light sources provide diffuse light.
In one embodiment the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and thereby illuminate edge features of the respective one of the workpieces.
In one embodiment the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
In one embodiment the imaging unit comprises a plurality of cameras, which each support a plurality of detectors and are movably disposed relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources. In one embodiment the cameras are moved in unison.
In one embodiment the cameras each support two detectors for detecting edge features at two spaced locations.
In one embodiment the cameras are disposed to at least one lateral side of the platen.
In one embodiment the cameras are disposed to opposite lateral sides of the platen.
In one embodiment the cameras are movable longitudinally relative to a direction of travel over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
In one embodiment the cameras are pre-aligned to one of the longitudinal positions in dependence upon the kind of workpiece to be handled, and, in movement between the inoperative and operative positions during image acquisition, the cameras are moved only in a single direction laterally to one of the lateral positions.
In one embodiment the light sources are mounted within the platen.
In one embodiment the light sources are mounted below the platen.
In one embodiment the detectors are operative to acquire images simultaneously.
In a further aspect the present invention provides a method of handling workpieces, comprising the steps of: providing a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the platen to transfer workpieces thereon to and from the platen, and a drive arrangement for driving the belt; providing an imaging unit comprising a plurality of discrete light sources which are arranged to illuminate respective edge features of a supported workpiece through the belt, and a plurality of detectors which are arranged to detect transmitted illumination from respective ones of the light sources; driving the belt to transfer a workpiece onto the platen; moving the detectors to operative, image acquisition positions in correspondence with respective ones of the light sources; and acquiring images of each of the respective edge features of the supported workpiece.
In one embodiment the body of the platen includes an air-permeable section which is operably connected to a vacuum or reduced pressure source, and the method further comprises the step of: applying a vacuum or reduced pressure to the air-permeable section to draw the supported workpiece to the platen and maintain the workpiece in fixed relation to the platen.
In one embodiment the air-permeable section comprises a porous component, optionally a sintered component.
In another embodiment the air-permeable section comprises an apertured component including an array of through bores therein.
In one embodiment the belt is an endless belt, a section of which is driven over the platen.
In one embodiment the belt is optically transmissive of light from the light source.
In one embodiment the belt is formed of silicone.
In one embodiment the belt includes a layer of silicone on an outer surface thereof. In one embodiment the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
In one embodiment the belt includes a support web, optionally a woven web.
In one embodiment the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
In one embodiment the belt includes a plurality of through apertures arranged in spaced relation thereover.
In one embodiment the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
In one embodiment the apertures are more closely spaced in an intermediate region of a width of the belt.
In one embodiment the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel of the belt, and a third group of apertures which is located intermediate the first and second groups of apertures.
In one embodiment the first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
In one embodiment the third group of apertures extends across a central region which is about one half of the width of the belt. In one embodiment the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
In one embodiment the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
In one embodiment the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, whereby rotation of at least one of the rollers causes rotation of the belt.
In one embodiment one of the rollers is driven, and the other of the rollers is free to follow the first roller.
In one embodiment the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
In one embodiment the belt aligner comprises a sensor which acts to detect one edge of the belt, and an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and the method further comprises the step of: causing the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
In one embodiment the direction of tracking of the belt is switched when the edge of the belt is no longer visible to the sensor. In one embodiment the light sources provide light in the visible spectrum.
In one embodiment the light has a wavelength of from about 640 nm to about 680 nm.
In one embodiment the light sources provide diffuse light.
In one embodiment the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and illuminating edge features of the respective one of the respective workpieces.
In one embodiment the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
In one embodiment the imaging unit comprises a plurality of cameras, which each support a plurality of detectors, and the method further comprises the step of: moving the cameras relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources.
In one embodiment the cameras are moved in unison.
In one embodiment the cameras each support two detectors for detecting edge features at two spaced locations.
In one embodiment the cameras are disposed to at least one lateral side of the platen.
In one embodiment the cameras are disposed to opposite lateral sides of the platen. In one embodiment the cameras are movable longitudinally relative to a direction of travel of the belt over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
In one embodiment the method further comprises the steps of: pre-aligning the cameras to one of the longitudinal positions in dependence upon the kind of workpiece to be handled; and moving the cameras in only a single direction laterally to one of the lateral positions between the inoperative and operative positions during image acquisition.
In one embodiment the light sources are mounted within the platen.
In one embodiment the light sources are mounted below the platen.
In one embodiment the detectors are operative to acquire images simultaneously.
Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which :
Figure 1 illustrates a perspective view of a workpiece handling system in accordance with a preferred embodiment of the present invention ;
Figure 2 illustrates a plan view of the workpiece handling system of Figure i ;
Figure 3 illustrates a plan view of the workpiece handling system of Figure 1, with the transport belt removed; Figure 4 illustrates a longitudinal sectional view (along section I-I in Figure 2) of the workpiece support unit of the workpiece handling system of Figure i ;
Figure 5 illustrates a plan view of the transport belt of the workpiece handling system of Figure 1 ;
Figure 6 illustrates a side view of the transport belt of Figure 5; and
Figure 7 illustrates a plan view of the transport belt of Figure 5, laid flat prior to fabrication in endless form.
The workpiece handling system comprises a workpiece support unit 3 which is operative to support a workpiece W in a processing operation, an infeed unit 5 for feeding workpieces W in succession to the workpiece support unit 3 for processing and an outfeed unit 7 for feeding workpieces W from the workpiece support unit 3 following processing.
The workpiece support unit 3 comprises a platen 9 which supports a workpiece W thereon during a processing operation, here a printing operation.
In this embodiment the platen 9 comprises a body 10, here having a substantially planar upper surface, and a belt 12 which extends over the upper surface of the body 10 and is operable to transfer workpieces W to and from the platen 9, here in a transport axis.
In this embodiment the body 10 includes an air-permeable section 15 which is operably connected to a vacuum or reduced pressure source, such that, on application of a vacuum or reduced pressure to the air-permeable section 15, a supported workpiece W is drawn thereto and maintained in fixed relation. In this embodiment the air-permeable section 15 comprises a porous component, here formed by sintering.
In an alternative embodiment the air-permeable section 15 could comprise an apertured component which includes an array of through bores therein.
In this embodiment the platen 9 further comprises a drive arrangement 19 which drives the belt 12 to transfer workpieces W.
In this embodiment the belt 12 is an endless belt, a section of which is driven over the upper surface of the platen 9.
In this embodiment the belt 12 is formed of silicone, but in other embodiments could include a layer of silicone on an outer surface thereof.
In this embodiment the outer surface of the belt 12 has a shore hardness (Shore D) of 40. In preferred embodiments the outer surface of the belt 12 has a shore hardness (Shore D) of from about 30 to about 50.
In this embodiment the belt 12 includes a support web, here in the form of a woven web.
In this embodiment the belt 12 has a thickness of about 0.7 mm. In preferred embodiments the belt 12 has a thickness of from about 0.2 mm to about 1.5 mm, preferably from about 0.2 mm to about 1.0 mm, more preferably from about 0.4 mm to about 1.0 mm, still more preferably from about 0.5 mm to about 0.9 mm, and yet still more preferably from about 0.6 mm to about 0.8 mm.
In this embodiment the belt 12 includes a plurality of through apertures 25, here arranged in spaced relation over a surface thereof, by which a vacuum or reduced pressure is transferred from the platen 9 to a workpiece W when supported thereon, such as to fix the workpiece W to the platen 9 for processing.
In this embodiment the apertures 25 have an average diameter of about 1.5 mm. In preferred embodiments the apertures 25 have an average diameter of from about 0.5 mm to about 2.5 mm, and preferably from about 1.0 mm to about 2.0 mm.
In this embodiment the apertures 25 are more closely spaced in an intermediate region of the belt 12 in the direction of travel.
In this embodiment the belt 12 includes first and second groups of apertures 25a, b which are located at edge regions of the belt 12 in the direction of travel, and a third group of apertures 25c which is located intermediate the first and second groups of apertures 25a, b.
In this embodiment the first and second groups of apertures 25a, b each extend across a region which is about one quarter the width of the belt 12.
In this embodiment the third group of apertures 25c extends across a central region which is about one half of the width of the belt 12.
In this embodiment the groups of apertures 25a-c are arranged such that the belt 12 includes a plurality of non-apertured regions 27 along the length thereof in the direction of travel. As will be described in more detail hereinbelow, the non-apertured regions 27 are arranged such that no apertures 25 are within the field of view of the detectors 65a, b of the cameras 61, 63.
In this embodiment the non-apertured regions 27 have a width, lateral to the direction of travel of the belt 12, of at least about 5 mm, preferably at least about 7 mm, more preferably at least about 10 mm. In this embodiment the belt 12 is sufficiently optically transparent to visible light as to enable transmission of illumination therethrough.
In this embodiment the drive arrangement 19 comprises first and second rollers 31, 33 which are disposed adjacent opposite ends of the platen 9 and receive the belt 12 thereon, such that rotation of at least one of the rollers 31, 33 causes rotation of the belt 12, and a drive (not illustrated) which is operable to drive the at least one of the rollers 31, 33.
In this embodiment one of the rollers 31, 33, here the first roller 31, is driven, and the other of the rollers 31, 33, here the second roller 33, is freely rotatable to follow the first roller 31.
In this embodiment the drive arrangement 19 comprises a belt aligner 41 which maintains the belt 12 at a predefined location on the rollers 31, 33.
In this embodiment the belt aligner 41 comprises a sensor 43 which acts to detect one edge of the belt 12, an actuator 45 which acts to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track in a respective one of the directions along a length of the rollers 31, 33, and a controller 47 which is operative to cause the actuator 45 to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track in one direction along a length of the rollers 31, 33, and, when the edge of the belt 12 is no longer visible to the sensor 43, to cause the actuator 45 to adjust the angular relationship of at least one of the rollers 31, 33 in relation to the belt 12 so as to cause the belt 12 to track back in the other direction along a length of the rollers 31, 33, and repeatedly cause the belt 12 to be tracked in the opposite directions in order to maintain the belt 12 at a predefined location. The workpiece handling system further comprises an imaging unit 51 for imaging a workpiece W when supported on the platen 9, whereby the position and/or orientation of the supported workpiece W is determined.
The imaging unit 51 comprises a plurality of discrete light sources 53a-d, 55a-d which are arranged within the platen 9 for illuminating respective edges of the supported workpiece W.
In this embodiment the light sources 53a-d, 55a-d are grouped in correspondence to the size and/or shape of workpieces W to be processed by the workpiece handling system.
In this embodiment the groups of light sources 53a-d, 55a-d are arranged such as to illuminate the respective edges of workpieces Wl, W2 of two different sizes, being rectangular and of 125x125 mm and 156x156 mm in size.
In this embodiment the light sources 53a-d, 55a-d provide light, here diffuse light, in the visible spectrum.
In this embodiment the light is red light having a peak wavelength of 660 nm and a spectral half-width of 20 nm. In preferred embodiments the light has a wavelength of from about 640 nm to about 680 nm.
In an alternative embodiment the light sources 53a-d, 55a-d could provide infra-red light, preferably in the near infra-red region.
The imaging unit 51 further comprises a plurality of, in this embodiment first and second cameras 61, 63 which are configured to acquire images of the respective edges of a supported workpiece W as illuminated by the respective light sources 53a-d, 55a-d. In this embodiment the cameras 61, 63 each comprise a plurality of detectors 65a, b in correspondence to the respective light sources 53a-d, 55a-d, whereby images of each of the respective edges of the workpiece W can be acquired simultaneously using the cameras 61, 63.
The imaging unit 51 further comprises a drive assembly 71 which is operative to move the respective cameras 61, 63 laterally (X) and transversely (Y) relative to the platen 9.
In this embodiment the drive assembly 71 comprises first and second drive units 73a, b which each comprise a first actuator 75 which is operable to move the respective camera 61, 63 laterally (X) and a second actuator 77 which is operable to move the respective camera 61, 63 transversely (Y).
With this configuration, the cameras 61, 63 can be pre-aligned laterally (X) relative to the platen 9 in dependence upon the kind of workpiece W to be imaged, here positions PI for the first kind of workpiece Wl and positions P2 for the second kind of workpiece W2, whereby, in an image acquisition step, the cameras 61, 63 are simultaneously driven only transversely (Y) relative to the platen 9, in this embodiment in a single operation, and the cameras 61, 63 are aligned with the respective light sources 53a-d, 55a-d in the platen 9.
This arrangement is particularly advantageous, in enabling image acquisition from different kinds of workpieces W in a very short cycle time, being determined by the time for the cameras 61, 63 to be simultaneously driven transversely (Y) to the image acquisition positions inboard of the platen 9 and returned to positions laterally outboard of the platen 9.
In addition, this arrangement, in detecting transmitted light, provides for an accurate determination of an edge of the workpiece W, in that the image comprises two regions of marked contrast, being a dark region corresponding to the workpiece W through which light is not transmitted and a light region which corresponds to the transmission of light beyond the edge of the workpiece W. Given this marked contrast, no significant image processing is required to identify that part of the image which corresponds to the edge of the workpiece W, as is typically required from a reflectance measurement.
Furthermore, this arrangement allows for the cameras 61, 63 to have a low profile, thereby typically requiring the platen 9 to be separated from processing equipment, in this embodiment a printing screen, by not more than about 15 mm.
In this embodiment the spacing between an upper surface of the camera 61, 63 and a lower surface of the printing screen thereabove is not more than about 3 mm and the spacing between a lower surface of the camera 61, 63 and an upper surface of the platen 9, here the surface of the belt 12, is not more than about 5 mm.
Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

Claims

1. A workpiece handling system for handling workpieces, comprising : a workpiece support unit which is operative to support a workpiece in a processing operation, wherein the workpiece support unit comprises a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the body to transfer workpieces thereon to and from the platen, and a drive arrangement which drives the belt to transfer workpieces; and
an imaging unit for imaging a supported workpiece, wherein the imaging unit comprises a plurality of discrete light sources which are arranged to illuminate respective edge features of the supported workpiece through the belt, and a plurality of detectors arranged in correspondence to the respective light sources to detect transmitted illumination from respective ones of the light sources, whereby images of each of the respective edge features can be acquired.
2. The system of claim 1, wherein the body of the platen includes an air- permeable section which is operably connected to a vacuum or reduced pressure source, such that, on application of a vacuum or reduced pressure to the air-permeable section, the supported workpiece is drawn to the platen and maintained in fixed relation to the platen.
3. The system of claim 2, wherein the air-permeable section comprises a porous component, optionally a sintered component.
4. The system of claim 2, wherein the air-permeable section comprises an apertured component including an array of through bores therein.
5. The system of any of claims 1 to 4, wherein the belt is an endless belt, a section of which is driven over the platen.
6. The system of any of claims 1 to 5, wherein the belt is optically transmissive of light from the light source.
7. The system of any of claims 1 to 6, wherein the belt is formed of silicone.
8. The system of any of claims 1 to 6, wherein the belt includes a layer of silicone on an outer surface thereof.
9. The system of any of claims 1 to 8, wherein the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
10. The system of any of claims 1 to 9, wherein the belt includes a support web, optionally a woven web.
11. The system of any of claims 1 to 10, wherein the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
12. The system of any of claims 1 to 11, wherein the belt includes a plurality of through apertures arranged in spaced relation thereover.
13. The system of claim 12, wherein the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
14. The system of claim 12 or 13, wherein the apertures are more closely spaced in an intermediate region of a width of the belt.
15. The system of claim 14, wherein the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel, and a third group of apertures which is located intermediate the first and second groups of apertures.
16. The system of claim 15, wherein the first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
17. The system of claim 15 or 16, wherein the third group of apertures extends across a central region which is about one half of the width of the belt.
18. The system of any of claims 12 to 17, wherein the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
19. The system of claim 18, wherein the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
20. The system of any of claims 1 to 19, wherein the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, such that rotation of the at least one of the rollers causes rotation of the belt, and a drive which is operable to drive the at least one of the rollers.
21. The system of claim 20, wherein one of the rollers is driven, and the other of the rollers is free to follow the first roller.
22. The system of any of claims 1 to 21, wherein the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
23. The system of claim 22, wherein the belt aligner comprises a sensor which acts to detect one edge of the belt, an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and a controller which is operative to cause the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
24. The system of claim 23, wherein the controller is operative to switch the direction of tracking of the belt when the edge of the belt is no longer visible to the sensor.
25. The system of any of claims 1 to 24, wherein the light sources provide light in the visible spectrum.
26. The system of claim 25, wherein the light has a wavelength of from about 640 nm to about 680 nm.
27. The system of claim 25 or 26, wherein the light sources provide diffuse light.
28. The system of any of claims 1 to 27, wherein the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and thereby illuminate edge features of the respective one of the workpieces.
29. The system of claim 28, wherein the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
30. The system of any of claims 1 to 29, wherein the imaging unit comprises a plurality of cameras, which each support a plurality of detectors and are movably disposed relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources.
31. The system of claim 30, wherein the cameras are moved in unison.
32. The system of claim 30 or 31, wherein the cameras each support two detectors for detecting edge features at two spaced locations.
33. The system of any of claims 30 to 32, wherein the cameras are disposed to at least one lateral side of the platen.
34. The system of claim 33, wherein the cameras are disposed to opposite lateral sides of the platen.
35. The system of claim 33 or 34, wherein the cameras are movable longitudinally relative to a direction of travel over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
36. The system of claim 35, wherein the cameras are pre-aligned to one of the longitudinal positions in dependence upon the kind of workpiece to be handled, and, in movement between the inoperative and operative positions during image acquisition, the cameras are moved only in a single direction laterally to one of the lateral positions.
37. The system of any of claims 1 to 36, wherein the light sources are mounted within the platen.
38. The system of any of claims 1 to 37, wherein the light sources are mounted below the platen.
39. The system of any of claims 1 to 38, wherein the detectors are operative to acquire images simultaneously.
40. A method of handling workpieces, comprising the steps of:
providing a platen for supporting a workpiece thereon, the platen comprising a body and a belt which extends over a surface of the platen to transfer workpieces thereon to and from the platen, and a drive arrangement for driving the belt;
providing an imaging unit comprising a plurality of discrete light sources which are arranged to illuminate respective edge features of a supported workpiece through the belt, and a plurality of detectors which are arranged to detect transmitted illumination from respective ones of the light sources;
driving the belt to transfer a workpiece onto the platen;
moving the detectors to operative, image acquisition positions in correspondence with respective ones of the light sources; and acquiring images of each of the respective edge features of the supported workpiece.
41. The method of claim 40, wherein the body of the platen includes an air-permeable section which is operably connected to a vacuum or reduced pressure source, and further comprising the step of: applying a vacuum or reduced pressure to the air-permeable section to draw the supported workpiece to the platen and maintain the workpiece in fixed relation to the platen.
42. The method of claim 41, wherein the air-permeable section comprises a porous component, optionally a sintered component.
43. The method of claim 41, wherein the air-permeable section comprises an apertured component including an array of through bores therein.
44. The method of any of claims 40 to 43, wherein the belt is an endless belt, a section of which is driven over the platen.
45. The method of any of claims 40 to 44, wherein the belt is optically transmissive of light from the light source.
46. The method of any of claims 40 to 45, wherein the belt is formed of silicone.
47. The method of any of claims 40 to 45, wherein the belt includes a layer of silicone on an outer surface thereof.
48. The method of any of claims 40 to 47, wherein the outer surface of the belt has a shore hardness (Shore D) of from about 30 to about 50, optionally from about 35 to about 45.
49. The method of any of claims 40 to 48, wherein the belt includes a support web, optionally a woven web.
50. The method of any of claims 40 to 49, wherein the belt has a thickness of from about 0.2 mm to about 1.5 mm, optionally from about 0.2 mm to about 1.0 mm, optionally from about 0.4 mm to about 1.0 mm, optionally from about 0.5 mm to about 0.9 mm, optionally from about 0.6 mm to about 0.8 mm.
51. The method of any of claims 40 to 50, wherein the belt includes a plurality of through apertures arranged in spaced relation thereover.
The method of claim 51, wherein the apertures have an average diameter of from about 0.5 mm to about 2.5 mm, optionally from about 1.0 mm to about 2.0 mm.
53. The method of claim 51 or 52, wherein the apertures are more closely spaced in an intermediate region of a width of the belt.
54. The method of claim 53, wherein the belt includes first and second groups of apertures which are located at respective edge regions of the belt in a direction of travel of the belt, and a third group of apertures which is located intermediate the first and second groups of apertures.
55. The method of claim 54, wherein the first and second groups of apertures each extend across a region which is about one quarter the width of the belt.
The method of claim 54 or 55, wherein the third group of apertures extends across a central region which is about one half of the width of the belt.
57. The method of any of claims 51 to 56, wherein the apertures are arranged such that the belt includes a plurality of non-apertured regions, optionally extending in spaced, parallel relation, along the length of the belt in the direction of travel, whereby the detectors, when in the respective image acquisition positions, each have a field of view, which images only the non-apertured regions of the belt.
58. The method of claim 57, wherein the non-apertured regions have a width, lateral to the direction of travel of the belt, of at least about 5 mm, at least about 7 mm or at least about 10 mm.
59. The method of any of claims 40 to 58, wherein the drive arrangement comprises first and second rollers which are disposed at opposite ends of the platen and receive the belt thereon, whereby rotation of at least one of the rollers causes rotation of the belt.
60. The method of claim 59, wherein one of the rollers is driven, and the other of the rollers is free to follow the first roller.
61. The method of any of claims 40 to 60, wherein the drive arrangement comprises a belt aligner which maintains the belt within a predefined location on the rollers.
62. The method of claim 61, wherein the belt aligner comprises a sensor which acts to detect one edge of the belt, and an actuator which acts to adjust the angular relationship of at least one of the rollers in relation to the belt so as to cause the belt to track in a respective one of the directions along a length of the rollers, and further comprising the step of:
causing the actuator to adjust the angular relationship of the at least one of the rollers in relation to the belt so as to cause the belt repeatedly to track in opposite directions along a length of the rollers within a defined location.
63. The method of claim 62, wherein the direction of tracking of the belt is switched when the edge of the belt is no longer visible to the sensor.
64. The method of any of claims 40 to 63, wherein the light sources provide light in the visible spectrum.
65. The method of claim 64, wherein the light has a wavelength of from about 640 nm to about 680 nm.
66. The method of claim 64 or 65, wherein the light sources provide diffuse light.
67. The method of any of claims 40 to 66, wherein the light sources comprise a plurality of groups of light sources, each group of light sources being configured in correspondence to the size and/or shape of a respective one of the workpieces to be processed by the workpiece handling system and illuminating edge features of the respective one of the respective workpieces.
68. The method of claim 67, wherein the groups of light sources are arranged to illuminate edge features of respective ones of two differently-sized rectangular workpieces.
69. The method of any of claims 40 to 68, wherein the imaging unit comprises a plurality of cameras, which each support a plurality of detectors, and further comprising the step of:
moving the cameras relative to the platen between inoperative positions and operative, image acquisition positions in which the detectors are aligned with the light sources.
70. The method of claim 69, wherein the cameras are moved in unison.
71. The method of claim 69 or 70, wherein the cameras each support two detectors for detecting edge features at two spaced locations.
72. The method of any of claims 69 to 71, wherein the cameras are disposed to at least one lateral side of the platen.
73. The method of claim 72, wherein the cameras are disposed to opposite lateral sides of the platen.
74. The method of claim 72 or 73, wherein the cameras are movable longitudinally relative to a direction of travel of the belt over the platen between a plurality of longitudinal positions in registration with the positions of the detectors in the platen and transversely across a width of the platen to a plurality of lateral positions in registration with the positions of the detectors.
75. The method of claim 74, further comprising the steps of:
pre-aligning the cameras to one of the longitudinal positions in dependence upon the kind of workpiece to be handled; and
moving the cameras in only a single direction laterally to one of the lateral positions between the inoperative and operative positions during image acquisition.
76. The method of any of claims 40 to 75, wherein the light sources are mounted within the platen.
77. The method of any of claims 40 to 76, wherein the light sources are mounted below the platen.
78. The method of any of claims 40 to 77, wherein the detectors are operative to acquire images simultaneously.
PCT/EP2014/059670 2013-05-11 2014-05-12 Workpiece handling system and method WO2014184149A1 (en)

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