WO1994009445A1 - Lecteur de code a barres a deux sources de lumiere - Google Patents

Lecteur de code a barres a deux sources de lumiere Download PDF

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Publication number
WO1994009445A1
WO1994009445A1 PCT/US1993/009979 US9309979W WO9409445A1 WO 1994009445 A1 WO1994009445 A1 WO 1994009445A1 US 9309979 W US9309979 W US 9309979W WO 9409445 A1 WO9409445 A1 WO 9409445A1
Authority
WO
WIPO (PCT)
Prior art keywords
bar code
code scanner
photodetector
light
light source
Prior art date
Application number
PCT/US1993/009979
Other languages
English (en)
Inventor
James S. Bianco
Bernard Drummond
Original Assignee
Control Module Inc.
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 Control Module Inc. filed Critical Control Module Inc.
Publication of WO1994009445A1 publication Critical patent/WO1994009445A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10544—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum
    • G06K7/10554—Moving beam scanning
    • G06K7/10564—Light sources
    • G06K7/10574—Multiple sources
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K2207/00—Other aspects
    • G06K2207/1013—Multi-focal

Definitions

  • the present invention relates to the reading of bar codes generally and, more particularly, to novel apparatus for reading bar codes, particularly those having variable print/contrast ratios, such as are encountered, for example, on silicon wafers during both the manufacture of the wafers and the manufacture of the integrated circuits on the wafers, during the production of heat treated parts such as turbine blades, during the manufacture of nuclear rods, and during the manufacture of compact disks.
  • Integrated circuits have found extensive use in digital data processing equipment and have permitted the size of such equipment to shrink by many orders of magnitude.
  • a number of such circuits are formed on a silicon wafer disk by successive deposition and etching steps, following which the disk is cut into individual circuits, or chips.
  • the wafers are marked with identifying bar codes which are typically etched into the surfaces of the wafers by the manufacturer of the wafers.
  • bar code reading devices used in such equipment provide poor performance, due to changing print/contrast ratios as the wafers move through the manufacturing process and due to the wide ranging reflectivity of the bar codes, the latter resulting from the fact that the bar codes are not printed on the wafers but are laser-etched into the surfaces thereof. Whether the bar code is acid or alkaline etched also introduces affects the ability of conventional bar code reading devices to read the codes with a single light source. If the bar code reader is of the scanning type having an oscillating light beam, there is a changing focal point as the bar code is scanned from end to end. The types of readers that have a detector of constant distance from the wafer require the additional complication that the position of the wafer be changed as attempts are made to read the bar code.
  • a bar code scanner for reading a bar code on a flat surface of an article, comprising: a first light source disposed so as to illuminate the bar code; a second light source disposed so as to illuminate the bar code; photodetector means disposed so as to detect light from the first and second light sources reflected from the bar code; and motive apparatus to cause relative motion between the bar code and the first and second light sources and the photodetector means so that the photodetector means can read the bar code, such that the focal length(s) between the photodetector means and the bar code remain(s) constant.
  • the photodetector means includes first and second photodetectors.
  • a bar code scanner of generally the foregoing construction, except that a beam splitter is employed to precisely direct light from the first and second light sources at the bar code and a single photodetector is employed to detect light reflected from both light sources. Discriminator slits are provided in front of the photodetectors in both embodiments.
  • Figure 1 is a top/front/right side perspective view of a bar code reader scanner constructed according to the present invention.
  • Figure 2 is a top/rear/left side perspective view of the embodiment of the bar code scanner.
  • Figure 3 is a front elevational view with the front cover removed of the bar code scanner.
  • Figure 4 is a top plan view of the bar code scanner with the top cover removed.
  • Figure 5 is a cross-sectional side elevational view taken along line "5-5" of Figure 4.
  • Figure 6 is a cross-sectional side elevational view taken along line "6-6" of Figure 4.
  • Figure 7 is a fragmentary top plan view of a portion of the mechanism of the bar code scanner.
  • Figure 8 is a fragmentary top plan view of another portion of the mechanism of the bar code scanner.
  • Figure 9 is a perspective view, partially schematic, illustrating the use of the bar code scanner with conventional silicon wafer positioning equipment.
  • Figure 10 is a front elevational view illustrating the use of the bar code scanner in a desktop embodiment.
  • Figure 11 is a side elevational view of the embodiment of Figure 11.
  • Figure 12 schematically illustrates the reading of a bar code with the present invention.
  • Figure 13 is a fragmentary, side elevation view, partially in cross-section of a bar code scanner constructed according to an alternative embodiment of the present invention.
  • Figure 14 is a schematic perspective view of the optical elements of the scanner of Figure 13.
  • FIGS 1-4 show more complete views of the bar code scanner of the present invention, generally indicated by the reference numeral 20, reference first to Figure 7 will aid in understanding the means by which motion is provided for linear raster scanning.
  • a guide bar 22 is rotatably fixed to rotating guide bar gears 24 and 26 by means of screws
  • Guide bar gears 24 and 26 are mounted on a horizontal support shelf 140.
  • guide bar gears 24 and 26 rotate as indicated by the arrows shown inside the peripheries thereof, guide bar 22 will have an overall rotary motion but will also have a continuous, back-and-forth, X-axis component of motion as indicated by the arrows "A-A" on Figure 7.
  • guide bar gears 24 and 26 are driven by the engagement therewith of center gear 30 of drive gear assembly 32.
  • bar code scanner 20 includes a carrier member 60 disposed for X- axis movement in a housing having a front cover 62, side covers 64 and 66, and a rear cover 68. Bar code scanner 20 also includes a base 70 ( Figures 5 and 6) and a top cover 72 ( Figures 1 and 2). It can be seen that the housing of bar code scanner 20 generally comprises a cube.
  • Carrier member 60 is partly supported and guided for movement back and forth along the X-axis by a main shaft 80 which is journalled in a linear bearing 86 disposed in the carrier member. Carrier member 60 is further supported and guided for movement back and forth along the X-axis by a guide shaft 82 which passes through the carrier member in closely fitting sliding relationship therewith.
  • any Y-axis component of the rotary motion of guide bar 22 will be negated with respect to carrier member 60 by the sliding motion of the guide bar 22 within lower portion 100 of the carrier member.
  • mounted channels formed in carrier member 60 are a first light source 400, a first lens 402, a first mirror 404, and a first photodetector 406.
  • the foregoing elements are arranged such that light from first light source will illuminate a bar code (not shown) on a surface 410.
  • Surface 410 may be any of those noted above.
  • Light reflected from surface 410 is focussed by first lens 402 onto first mirror 404 which reflects the light to photodetector 406, as will be described in more detail below. It can be seen that light from first light source 400 strikes surface 410 at approximately a 45- degree angle therewith and that first lens 402 focuses light reflected from the surface at approximately a 45- degree angle therewith.
  • a second light source 420 mounted in channels formed in carrier member 60 are a second light source 420, a second lens, a second mirror 424, and a second photodetector 426.
  • the foregoing elements are arranged such that light from second light source will illuminate the bar code on surface 410.
  • Light reflected from surface 410 is focussed by second lens 422 onto first mirror 424 which reflects the light to photodetector 426, as will be described in more detail below. It can be seen that light from second light source 420 strikes surface 410 at approximately a 45- degree angle therewith and that second lens 422 focuses light reflected from the surface at approximately a 45-degree angle therewith.
  • a flexible flat cable 124 ( Figures 3 and 6) connects first and second lights 400 and 420 and first and second photodetectors 406 and 426 to printed circuit board 126 which includes circuitry for speed control and adjustment for motor 36.
  • a receptacle 128 ( Figure 2) is provided in rear cover 68 for attachment of a cable (not shown) to supply power to bar code scanner 20 and to receive signals therefrom.
  • motor 36 ( Figure 3), through the gearing mechanisms described above, provides horizontal X-axis motion for carrier member 60, such that the first and second light sources 400 and 420 and their associated components move with a back-and- forth motion under surface 410 with a constant focal point on the surface placed over a rectangular opening 136 ( Figures 1 and 2) defined in top cover 72, under which opening the first and second light sources and their associated components move.
  • bar code scanner 20 which is preferably on the order of about two inches on each side, the length of the X-axis sweep is on the order of about 0.75 inch. While bar code scanner 20 may be used in a number of applications, there will be first described the use of the bar code scanner with conventional means for positioning a silicon wafer substrate, to which conventional means the bar code scanner can be easily retrofitted.
  • a wafer 210 positioned above a horizontal disk 212 rotatable by motor 214 and above two, horizontally extending arms 216 and 218 which are movable in and out, that is, toward and away, from the axis of motor 214 and up and down, to lift the wafer from the disk or to place the wafer onto the disk. It will be understood that when wafer 210 is placed on disk 212, the wafer will rotate with the disk.
  • a notch, or flat portion, 224 Formed in the periphery of disk 212 is a notch, or flat portion, 224 and formed on the upper surface of the disk, slightly inward from the periphery thereof, and at a known angle with respect to the notch is a bar code 226 which is etched into the disk with a laser (not shown).
  • Motor 214 and arms 216 and 218 are controlled by index controller 230 which is interconnected with robotics controller 232.
  • Robotics controller 232 receives inputs from bar code scanners 20 and 20' through serially connected analog- to-digital converter 250 and bar code decoder 252. When a wafer, such as wafer 210, is to be positioned, it is moved onto arms 216 and 218 by other equipment (not shown).
  • Arms 216 and 218 then lower wafer 210 onto disk 212 which rotates the disk.
  • Optical sensing equipment (not shown) which provides input to index controller 230 detects the concentricity of, or lack of, the periphery of wafer 210 with respect to disk 212. If the optical sensing equipment detects nonconcentricity of disk 212, index controller 230 causes the rotation to cease, arms 216 and 218 to lift wafer 210 from disk 212, and the arms to move the wafer in or out from the axis of motor 214 to correct for the nonconcentricity of the disk. Arms 216 and 218 then replace wafer 210 on disk 212 and the wafer is again rotated.
  • Wafer 210 is then removed from the positioning operation by other equipment (not shown), while precisely maintaining the position of the wafer, and the wafer is moved to bar code reading equipment (not shown).
  • the bar code reading equipment causes the wafer to continuously rotate.
  • An optical sensor located radially a distance from the center of the wafer at approximately the radial distance of bar code 226 oscillates in and out slightly until the bar code is read.
  • the conventional method is relatively slow, in that there is a large amount of "no read" time when the bar code is not in proximity to the optical sensor.
  • bar code scanner 20' Disposed centrally of a horizontal cross-bar 240 which supports arms 216 and 218 is an upwardly facing bar code scanner 20' .
  • a frame 244 formed as an extension of cross-bar 240 is a downwardly facing optical bar code scanner 20.
  • Both bar code scanners 20 and 20' may be furnished when bar codes may be placed on either the top or the bottom of wafer 210 or only one or the other may be furnished if bar codes will be placed on only the same side of each wafer.
  • the distances separating the elements shown on Figure 10 are exaggerated for clarity and whichever of optical sensors 20 and 20' is being used, it would be positioned about 0.010-0.020 inch from the surface of wafer 210 bearing the bar code.
  • notch 224 is located with the optical sensing equipment (not shown) and the wafer is rotated to place bar code 226, or a similar bar code if printed on the lower surface of wafer 210, in reading proximity to optical sensors 20 and 20' and the wafer is held motionless on disk 212.
  • Index controller 230 is then commanded by robotics controller 232 to move the appropriate one of optical sensors 20 and 20' near the surface of the wafer. If it is unknown whether the bar code is on the upper or the lower surface of wafer 210, the location can be determined by reading with one and then the other of bar code scanners 20 and 20' .
  • a further advantage of the present invention is that bar code scanners 20 and 20' can be automatically moved in or out to compensate for different diameter wafers. After positioning of the appropriate one of bar code scanners 20 and 20', bar code 226 is scanned by the raster scanning of the light source/photodetector in the bar code scanner and the bar code is read and decoded in the conventional manner. Wafer 210 can then be moved to another station.
  • FIGs 10 and 11 illustrate another application for bar code scanner 20, here, in a desktop silicon wafer reader, generally indicated by the reference numeral 300.
  • Reader 300 includes a base member 302, which may be attached to a bench or desktop, and an operating housing 304 selectively rotatable from a position (not shown) in which the housing is folded around the base member to an inclined position (shown on Figures 10 and 11) as indicated by the arrow marked "C" .
  • Operating housing 304 is held in the inclined position by means of a releasable support member 306.
  • a locating boss 310 is formed on on the upper surface of operating housing 304 to locate thereon a silicon wafer 312 (Figure 11 only) by means of engagement therewith by a notch (not shown) formed in the edge of the wafer adjacent the bar code.
  • a keyboard 320 is provided on the face of operating housing 304 to enter such commands as ON, OFF, VACUUM ON, VACUUM OFF, AND READ.
  • An LCD screen 322 is also provided on the face of operating housing 304 to indicate such information as operating status and the decoded bar code.
  • a cable 324 is connected to scanner 300 from a source of electrical power (not shown) . Cable 324 may also provide connection to central computer equipment (not shown).
  • wafer 312 is placed on the upper surface of operating housing 304, with an indexing notch (not shown) formed in the edge of the wafer engaging locating boss 310 such that a bar code on the wafer is located over a window 330 in the upper surface.
  • Vacuum is applied at openings 314 and the bar code on wafer 312 read by scanner 20 through window 330. The vacuum is then released and wafer 312 is removed. It will be understood that scanner 20 is so disposed in operating housing 304 that the plane of scanning is parallel to the plane of the bar code.
  • Reader 300 may be used in either the folded or the inclined position, the inclined position being most suitable for manual use of the reader and the folded position being most suitable for use of the reader when a robotic arm is used to place and remove the wafers.
  • the reader operations may be controlled by a remote computer console connected to the reader.
  • Reader 300 is useful in engineering and development settings and as a secondary checking apparatus during manufacturing processes.
  • Photodetectors 406 and 426 are of the type that employ therein discriminator slits such as described in US Patent No. 4,816,659, issued March 28, 1989, to James S. Bianco et al., and titled BAR CODE READER HEAD, the disclosure of which patent is incorporated by reference hereinto. As is described in that patent, discriminator slits are provided 514 to sharpen the image seen by a photodetecting element.
  • Figure 12 schematically illustrates first light source 400 and first photodetector 406 in reading relationship with a bar code 450.
  • First photodetector 406 includes therein a first discriminator slit 460.
  • Second light source 420 and second photodetector 426 are also disposed in reading relationship with bar code 450 and the second photodetector includes therein a second discriminator slit 462.
  • discriminator slits are disposed parallel to each other and to the bars of bar code 450. It will be understood that first and second photodetectors 400 and 420 and first and second photodetectors 406 and 426 will be moved relative to bar code 450 in the directions indicated by the arrows on Figure 12.
  • First light source/photodetector 400/406 and second light source/photodetector 420/426 may be arranged so that they simultaneously read the area on bar code 450 and the outputs from the photodetectors may be added, by conventional means, so that the bar code signal is amplified to increase the chance of reading the bar code.
  • first and second light sources 400 and 420 produce light of different wavelengths, the two wavelengths being a pair selected from visible, infrared, ultraviolet, or two different wavelengths within the foregoing ranges, so as to further increase the chance of reading bar code 450, especially when a coating has been placed over part or all of the bar code and to compensate for variations in acid and alkaline etching.
  • first light source/photodetector 400/406 and second light source/photodetector 420/426 may be arranged so that the areas read by the pairs are displaced vertically on bar code 450, so as to increase the chance of reading the bar code.
  • Figure 13 illustrates an alternative carrier design 60' for use in a bar code scanner, generally indicated by the reference number 20". Since the elements of bar code scanner 20", other than carrier 60" and the optical elements therein, are identical to those described above with reference to bar code scanner 20, no further discussion thereof will be made here.
  • Carrier 60" includes first and second light sources 500 and 502, respectively, and a mirror type beam splitter 504 arranged so that the first light source illuminates a bar code (not shown) on surface 410 by having a beam of light from that light source reflected from a surface of the beam splitter.
  • Second light source 502 illuminates the bar code by having a beam of light from that light source pass through the beam splitter.
  • the arrangement of these elements, as well as the other optical elements in carrier 60" is also shown schematically on Figure 14.
  • Light reflected from surface 410 passes through a focussing lens 510 and is reflected from a mirror 512, at approximately a 22 degree angle, to a photodetector 516 through a discriminator slit 514.
  • Mirror 512 is provided to minimize the height dimension of carrier 60".
  • first and second light sources 500 and 502 may not be reflected and transmitted equally by beam splitter 504, the intensities of the light sources may have to be different. For example, if beam splitter reflects 80 percent of the light from first light source 500 and transmits 20 percent of the light from second light source 502, then the first light source may have an intensity of 25 lumens, while the second light source may have an intensity of 100 lumens.
  • first and second light sources 500 and 502 may produce illumination in the visible, ultraviolet, and/or infrared spectrums.
  • the bar code reader of the parent application referenced above be modified, in accordance with the present teaching, for raster scanning with two light sources, so as to even further increase the chance of reading bar codes of low print contrast.
  • This can be simply accomplished by substituting carrier member 60 or 60" described herein for the carrier member of the bar code scanner of that disclosure.
  • the use of raster scanning may be avoided, in some cases, by directing two light sources at different elevations on the bar code.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

Dans une forme de réalisation préférée un lecteur de code à barres utilisé pour lire un code à barres placé sur une surface plane d'un article (410) comprend: une première source de lumière (400) qui est placée de manière à éclairer le code à barres; une deuxième source de lumière (420) placée de manière à détecter la lumière émise par les première et deuxième sources de lumière et réfléchie par le code à barres; et un appareil moteur qui provoque le mouvement relatif (A--A) entre le code à barres et les première et deuxième sources de lumière ainsi que le photodétecteur de sorte que ce dernier puisse lire le code à barres, et que la (ou les) focale(s) entre le photodétecteur et le code à barres reste(nt) constantes. Dans une première autre forme de réalisation le photodétecteur comprend des premier (406) et deuxième (426) photodétecteurs et dans une deuxème autre forme de réalisation le lecteur de code à barres est globalement construit de la même manière sauf qu'on utilise un système de fractionnement (504) de faisceau pour diriger avec précision la lumière émise par les première (500) et deuxième (502) sources de lumière sur le code à barres, et un seul photodétecteur (516) pour détecter la lumière réfléchie émise par les deux sources de lumière. Dans ces deux formes de réalisation des fentes (460, 462, 514) de discrimination sont prévues devant les photodétecteurs.
PCT/US1993/009979 1992-10-19 1993-10-19 Lecteur de code a barres a deux sources de lumiere WO1994009445A1 (fr)

Applications Claiming Priority (2)

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US96313892A 1992-10-19 1992-10-19
US07/963,138 1992-10-19

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WO1994009445A1 true WO1994009445A1 (fr) 1994-04-28

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117963453A (zh) * 2024-03-28 2024-05-03 江苏冠宇机械设备制造有限公司 一种具有测试功能的汽车制造输送线
CN117963453B (zh) * 2024-03-28 2024-06-07 江苏冠宇机械设备制造有限公司 一种具有测试功能的汽车制造输送线

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3812325A (en) * 1970-08-18 1974-05-21 Chesapeake & Ohio Railway Means for reading and interpreting color-coded identification labels
US4473746A (en) * 1981-07-30 1984-09-25 Bell & Howell Company Multiple head optical scanner
US4816659A (en) * 1987-10-13 1989-03-28 Control Module Inc. Bar code reader head
US5175420A (en) * 1991-03-20 1992-12-29 Bianco James S Bar code scanner having a light source/photodetector movable in a raster pattern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3812325A (en) * 1970-08-18 1974-05-21 Chesapeake & Ohio Railway Means for reading and interpreting color-coded identification labels
US4473746A (en) * 1981-07-30 1984-09-25 Bell & Howell Company Multiple head optical scanner
US4816659A (en) * 1987-10-13 1989-03-28 Control Module Inc. Bar code reader head
US5175420A (en) * 1991-03-20 1992-12-29 Bianco James S Bar code scanner having a light source/photodetector movable in a raster pattern

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117963453A (zh) * 2024-03-28 2024-05-03 江苏冠宇机械设备制造有限公司 一种具有测试功能的汽车制造输送线
CN117963453B (zh) * 2024-03-28 2024-06-07 江苏冠宇机械设备制造有限公司 一种具有测试功能的汽车制造输送线

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