WO1992016909A1 - Bar-code reader - Google Patents

Bar-code reader Download PDF

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Publication number
WO1992016909A1
WO1992016909A1 PCT/GB1992/000515 GB9200515W WO9216909A1 WO 1992016909 A1 WO1992016909 A1 WO 1992016909A1 GB 9200515 W GB9200515 W GB 9200515W WO 9216909 A1 WO9216909 A1 WO 9216909A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
light
bar
code reader
light pipe
inlet
Prior art date
Application number
PCT/GB1992/000515
Other languages
French (fr)
Inventor
John Keir Haffenden
Original Assignee
Dansam Holdings Limited
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

Links

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10544Methods 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
    • G06K7/10821Methods 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 further details of bar or optical code scanning devices
    • G06K7/10831Arrangement of optical elements, e.g. lenses, mirrors, prisms
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10544Methods 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
    • G06K7/10712Fixed beam scanning
    • G06K7/10722Photodetector array or CCD scanning

Abstract

This invention relates to a bar-code reader for transferring an optical image to an optoelectronic processing unit, for applications such as the reading of bar-codes on goods for sale in supermarkets. The bar-code reader comprises a light inlet (11) and an image detector, light being conveyed from the light inlet (11) to the image detector by means of a light pipe (1), which may comprise any suitably shaped solid body made of a transparent material. The light pipe (1) may be angled at at least one corner and have matt outer surfaces except at the or each corner where the outer surface is polished and at regions where the light is to be transmitted into or out of the light pipe (1). This arrangement allows the bar-code image to be conveyed from the light inlet (11) to the image detector along a bent path without significant loss of intensity of the bar-code image. Preferably the light pipe (1) is formed as a light trap to illuminate multi-paths from the inlet (11) to the image detector. Typically this may be achieved by forming notches, angles or serrations (7) in the side of the light pipe (1).

Description

9

BAR-CODE READER

This invention relates to a bar-code reader for transferring an optical image to an optoelectronic processing unit, for applications such as the reading of bar-codes on goods for sale in supermarkets. The use of bar-code readers has increased substantially in recent years in retail outlets such as supermarkets. Use of the bar-code on a product is an easy method of conveying the product identity, and a bar-code reader in combination with a database can significantly help to improve stock control and checkout times. Furthermore, a bar-code reader, adapted for customer use, may be employed in a check¬ out installation such as is described in British Patent Applicaτion No. 9013042.8 (Serial No. ). In such a system, a bar code reader is associated with each customer trolley or basket, and customers use the bar-code readers to identify goods which they select. The bar-code readers include memories for storing data relating to the goods for sale in the supermarket, and processing devices for calculating, inter alia, the total price and total weight of goods selected by a customer.

Current bar-code readers are either fixed installations, where the goods are passed over the bar¬ code reader, or incorporated within hand-held units which are placed near to each bar-code to read it. The optical image is then passed to a detection device, typically a charge-coupled device. These bar-code readers have the disadvantage that the light path from the input to the detection device cannot be bent without the use of mirrors. In many situations it may be desirable to bend the path of light for example to enable a more compact arrangement. The use of mirrors to achieve the required bent light path reduces the ability of the bar-code reader to withstand shocks such as those sustained when dropped or knocked.

The performance of the bar-code reader is directly related to the quality of the optical image that is received by the detection device. The bar-code reader must therefore maximise the amount of reflected light received from the bar-code and minimise interference from other sources.

Thus the present invention seeks to provide a bar- code reader which at least alleviates the disadvantages of the known devices.

According to the present invention there is provided a bar-code reader having a light inlet and an image detector, further including a light pipe for conveying light from the light inlet to the image detector.

The light pipe-may be any suitably shaped solid body made of a transparent material.

This provides the advantage that the light path from the light inlet to the image detector may be bent, while the reader is mechanically robust.

The present invention also provides a bar-code reader wherein the light pipe is angled at at least one corner and wherein the light pipe has matt outer surfaces except at the or each corner where the outer surface is polished and at regions where light is to be transmitted into or out of the light pipe.

This arrangement allows the bar-code image to be conveyed from the light inlet to the image deteeter along a bent path without significant loss of intensity of the bar-code image, as reflection occurs at polished surfaces, whilst light from other sources entering the light pipe will be severely attenuated by reflection at the matt surfaces. Preferably the light pipe is formed as a light trap to eliminate multipaths from the inlet to the i age detector.

Typically this may be achieved by forming notches, angles or serrations in the side of the light pipe.

This arrangement has the advantage that the bar- code image is not affected, but the multipath images, i.e. images which would be formed at the image detector following multiple reflections of the incoming light off the internal surfaces of the light pipe, which degrade the bar-code image are trapped and prevented from reaching the image detector.

In one preferred embodiment the bar-code reader further includes a light source, the light pipe having a thickened portion between the light source and the light inlet, and the light source being positioned to supply light through the thickened portion of the light pipe and out through the light inlet to illuminate a bar-code positioned adjacent the light inlet.

This arrangement provides local illumination of the bar-code which ensures that the reflected image is easily read.

The bar-code reader may be adapted for hand held operation. This enables the bar-code reader to be used to read bar-codes on heavy or awkward items and also to provide an ability to read codes at a distance from the base unit. Furthermore, the bar-code reader may be adapted for customer use, in an installation as described in British Patent Application No. 9013042.8 (Serial No. ).

For a better understanding of the present invention, and to show more clearly how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-

Figures la and lb show, schematically, the construction of a light pipe for use in a bar-code reader according to this invention;

Figure 2 illustrates the arrangement of a light pipe in a bar-code reader according to one embodiment of the present invention; and

Figure 3 shows an alternative embodiment of bar¬ code reader having a separate light emitting pipe. In a bar-code reader in accordance with the present invention, the light pipe provides a path for the light reflected by a bar-code to an optoelectronic detector and processor. The reader must also provide local illumination of the bar-code while minimising external light and light from multipaths entering the detection process.

The light pipe 1 for use in a bar-code reader according to an embodiment of the present invention is shown in Figures la and lb. The light pipe 1 guides light from a light inlet 11 to an outlet 12. The light pipe is a clear plastics moulding, typically made of perspex or polyacrylat , which has been shaped and selectively polished so that the light entering may be guided without the use of mirrors to the outlet. At the light inlet 11 and outlet 12, the surface of the light pipe is polished. LEDs 2 are used to illuminate the bar-code and are positioned behind the illumination inlet 3 at the head of the light pipe. The illumination inlet 3 is a polished surface of the light pipe, and the LEDs 2 are angled so that light from them is directed to a common reading point in front of the light pipe where the bar-code is to be positioned. The LEDs 2 are positioned so that as much light as possible is reflected into the light pipe from the bar-code. The bar-code image thus enters the light pipe 1. As is illustrated most clearly in Figure lb the light pipe may be bent and the surface 5 of the light pipe is polished at'the or each corner to effect bending of the light path round the corner using internal reflection at the plastics/air .interface. All other surfaces 6 of the pipe, apart from the inlets 3,11 and the outlet 12, are matt .

Located at the outlet 12 of the light pipe is a lens 13 which provides an image to a CCD image detector. In order that the optoelectronics is able to decode the bar-code accurately, the light received at the lens 13 from the light pipe must be predominantly the reflected bar-code image and therefore other light sources must be eliminated or their intensity reduced. The light passing through the light pipe comes from three main sources. The first is the image directly reflected from the bar-code which passes down the light pipe to the lens 13 by reflection at the polished surfaces. However, light is also reflected from the bar-code in all directions and some of this light enters the light pipe and will pass down the light pipe to the lens by internal reflection at the light pipe walls. In addition a small amount of external light will enter the light pipe through the external polished surface.

The interference from these light sources is minimised by the matt surfaces 6 of the light pipe because a considerable proportion of the light is lost during reflections at matt surfaces. In addition multipath interference which causes "flare" is further eliminated by notches or serrations 7 cut in the sides of the light pipe which reflect light away from the lens.

Figure 2 shows the light pipe of Figure 1 incorporated into a hand-held bar-code reader.

The reader has a top casing 8 and a bottom casing 9 shaped to permit easy and efficient use of the bar¬ code reader. The use of the light pipe 1 enables the light path to be bent and hence allows the casing to be designed for maximum ease of use.

The illumination of the bar-code is provided by a local bank of high brightness LEDs 2. The LEDs are spaced across the front of the reader, but are ancled to ensure that the reflected beam is directed towards the optical centre of the lens 13. The reflected bar-code image is captured by the light pipe 1 which passes it to the lens 13 and a light box 4 containing a CCD 14, by means of internal reflection at the polished surface 5.

The CCD is a linear array of photodiodes which detects the incoming image and converts it to an electronic signal. The output of the CCD is amplified and then applied to a threshold amplifier which converts the analogue signal from the CCD to a digital signal for interfacing with the processor. Otherwise, the general form of the reader is conventional, and it includes a battery compartment 15, a switch 16, and a display 17. The reader also contains any memory or processing capability required for its operation in the particular system being used. Thus, a bar-code reader according to this invention provides improved performance both optically and mechanically.

Figure 3 shows an alternative embodiment of bar¬ code reader, in which the LEDs 2 which are used to illuminate the bar-code are set back from the light inlet 11. A light emitting pipe 20 directs the light from the LEDs 2 to the light inlet 11. As is clear from Figure 3, the position of the light emitting pipe 20 or the light pipe 1 may be varied within the body of the bar-code reader. The principle of operation would remain the same, since the light is contained within the light emitting pipe 20 and the light pipe 1 therefore guaranteeing stability of omission and collection in relation to the light source (e.g. the LEDs 2), the front opening of the reader (e.g. the light inlet 11) and the lens 13. The light emitting pipe 20 may be constructed in a similar manner to the light pipe 1.

Claims

1. A bar-code reader having a light inlet and an image detector, further including a light pipe for conveying light from the light inlet to the image detector.
2. A bar-code reader as claimed in claim 1, wherein the light pipe is made of plastics.
3. A bar-code reader as claimed in claim 1 or 2, wherein the light pipe is angled at at least one corner and wherein the light pipe has a polished outer surface at the or each corner.
4. A bar-code reader according to one of claims 1 to 3 characterised in that the light pipe is formed as a light trap to eliminate multipaths from the inlet to the image detector.
5. A bar-code reader as claimed in claim 4, wherein the light pipe has notches, angles or serrations formed in side surfaces thereof.
6. A bar-code reader as claimed in any preceding claim, further including a light source, the light pipe having a thickened portion between the light source and the light inlet, and the light source being positioned to supply light through the thickened portion of the light pipe and through the light inlet to illuminate a bar-code positioned adjacent the light inlet.
7. A bar-code reader as claimed in any preceding claim, adapted for hand-held use, and including a power source.
8. A bar-code reader as claimed in one of claims 1 to 6, adapted for hand-held use, and including a flexible connection to a base unit.
9. A bar-code reader, substantially as herein described with reference to the accompanying drawings.
PCT/GB1992/000515 1991-03-21 1992-03-20 Bar-code reader WO1992016909A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9105969.1 1991-03-21
GB9105969A GB9105969D0 (en) 1991-03-21 1991-03-21 Bar-code reader

Publications (1)

Publication Number Publication Date
WO1992016909A1 true true WO1992016909A1 (en) 1992-10-01

Family

ID=10691932

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/000515 WO1992016909A1 (en) 1991-03-21 1992-03-20 Bar-code reader

Country Status (2)

Country Link
GB (1) GB9105969D0 (en)
WO (1) WO1992016909A1 (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5481101A (en) * 1993-12-10 1996-01-02 Teiryo Sangyo Co., Ltd. Two dimensional code data reading apparatus and method
US5786585A (en) * 1992-12-04 1998-07-28 Psc, Inc. Optical symbol (bar code) reading systems and devices
US6244509B1 (en) * 1999-08-30 2001-06-12 Nauchno-Teknichesky Kooperative (Vector) Scanning device for capturing images using a light guide
WO2005086071A2 (en) * 2004-03-02 2005-09-15 Symbol Technologies, Inc. System and method for reading optical codes imprinted on or displayed on reflective surfaces
US7163149B2 (en) 2004-03-02 2007-01-16 Symbol Technologies, Inc. System and method for illuminating and reading optical codes imprinted or displayed on reflective surfaces
US7823789B2 (en) 2004-12-21 2010-11-02 Cognex Technology And Investment Corporation Low profile illumination for direct part mark readers
US7874487B2 (en) 2005-10-24 2011-01-25 Cognex Technology And Investment Corporation Integrated illumination assembly for symbology reader
US9070031B2 (en) 2003-10-24 2015-06-30 Cognex Technology And Investment Llc Integrated illumination assembly for symbology reader
US20150338349A1 (en) * 2014-05-20 2015-11-26 Roche Diagnostics Operations Inc. bG METER ILLUMINATED TEST STRIP
US9292724B1 (en) 2004-12-16 2016-03-22 Cognex Corporation Hand held symbology reader illumination diffuser with aimer optics
US9298960B2 (en) 2003-10-24 2016-03-29 Cognex Corporation Method and apparatus for providing omnidirectional lighting in a scanning device
US9329332B2 (en) 2003-10-24 2016-05-03 Cognex Corporation Light pipe illumination system and method
US9361495B2 (en) 2004-12-16 2016-06-07 Cognex Technology And Investment Llc Hand held symbology reader illumination diffuser
US9536124B1 (en) 2003-10-24 2017-01-03 Cognex Corporation Integrated illumination assembly for symbology reader

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2161924A1 (en) * 1971-10-23 1973-07-13 Marconi Co Ltd
EP0071304A1 (en) * 1981-07-30 1983-02-09 Philips Electronics N.V. Device for the optical scanning of a document
EP0094571A2 (en) * 1982-05-19 1983-11-23 Msi Data Corporation Self-contained portable data entry terminal
DE3423131A1 (en) * 1984-06-22 1986-01-16 Ts Optoelectronic Gmbh Arrangement for reading bar codes and method for producing it
GB2163584A (en) * 1984-08-21 1986-02-26 Paul Fuller Bar-code reader
WO1986005280A1 (en) * 1985-03-01 1986-09-12 Telefonaktiebolaget L M Ericsson Lightpen

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2161924A1 (en) * 1971-10-23 1973-07-13 Marconi Co Ltd
EP0071304A1 (en) * 1981-07-30 1983-02-09 Philips Electronics N.V. Device for the optical scanning of a document
EP0094571A2 (en) * 1982-05-19 1983-11-23 Msi Data Corporation Self-contained portable data entry terminal
DE3423131A1 (en) * 1984-06-22 1986-01-16 Ts Optoelectronic Gmbh Arrangement for reading bar codes and method for producing it
GB2163584A (en) * 1984-08-21 1986-02-26 Paul Fuller Bar-code reader
WO1986005280A1 (en) * 1985-03-01 1986-09-12 Telefonaktiebolaget L M Ericsson Lightpen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IBM TECHNICAL DISCLOSURE BULLETIN vol. 25, no. 5, October 1982, NEW YORK pages 2362 - 2363; W.M. ROUTT: 'REFLECTIVE OBJECT SENSOR' *

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5786585A (en) * 1992-12-04 1998-07-28 Psc, Inc. Optical symbol (bar code) reading systems and devices
US5481101A (en) * 1993-12-10 1996-01-02 Teiryo Sangyo Co., Ltd. Two dimensional code data reading apparatus and method
US6244509B1 (en) * 1999-08-30 2001-06-12 Nauchno-Teknichesky Kooperative (Vector) Scanning device for capturing images using a light guide
US9070031B2 (en) 2003-10-24 2015-06-30 Cognex Technology And Investment Llc Integrated illumination assembly for symbology reader
US9329332B2 (en) 2003-10-24 2016-05-03 Cognex Corporation Light pipe illumination system and method
US9298960B2 (en) 2003-10-24 2016-03-29 Cognex Corporation Method and apparatus for providing omnidirectional lighting in a scanning device
US9536124B1 (en) 2003-10-24 2017-01-03 Cognex Corporation Integrated illumination assembly for symbology reader
US7163149B2 (en) 2004-03-02 2007-01-16 Symbol Technologies, Inc. System and method for illuminating and reading optical codes imprinted or displayed on reflective surfaces
WO2005086071A3 (en) * 2004-03-02 2005-12-15 Symbol Technologies Inc System and method for reading optical codes imprinted on or displayed on reflective surfaces
WO2005086071A2 (en) * 2004-03-02 2005-09-15 Symbol Technologies, Inc. System and method for reading optical codes imprinted on or displayed on reflective surfaces
US9361495B2 (en) 2004-12-16 2016-06-07 Cognex Technology And Investment Llc Hand held symbology reader illumination diffuser
US9292724B1 (en) 2004-12-16 2016-03-22 Cognex Corporation Hand held symbology reader illumination diffuser with aimer optics
US7823789B2 (en) 2004-12-21 2010-11-02 Cognex Technology And Investment Corporation Low profile illumination for direct part mark readers
US9495573B2 (en) 2004-12-21 2016-11-15 Cognex Technology And Investment Corporation Low profile illumination for direct part mark readers
US7874487B2 (en) 2005-10-24 2011-01-25 Cognex Technology And Investment Corporation Integrated illumination assembly for symbology reader
US9405951B2 (en) 2005-10-24 2016-08-02 Cognex Technology And Investment Llc Integrated illumination assembly for symbology reader
US20150338349A1 (en) * 2014-05-20 2015-11-26 Roche Diagnostics Operations Inc. bG METER ILLUMINATED TEST STRIP
US10036709B2 (en) * 2014-05-20 2018-07-31 Roche Diabetes Care, Inc. BG meter illuminated test strip

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