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WO2009061317A1 - Optical code scanner with automatic focusing - Google Patents

Optical code scanner with automatic focusing

Info

Publication number
WO2009061317A1
WO2009061317A1 PCT/US2007/084043 US2007084043W WO2009061317A1 WO 2009061317 A1 WO2009061317 A1 WO 2009061317A1 US 2007084043 W US2007084043 W US 2007084043W WO 2009061317 A1 WO2009061317 A1 WO 2009061317A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
code
scanner
distance
optical
range
Prior art date
Application number
PCT/US2007/084043
Other languages
French (fr)
Inventor
Kazukuni Hosoi
Original Assignee
Optoelectronics Co., Ltd.
Opticon, 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

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
    • G06K7/10792Special measures in relation to the object to be scanned
    • G06K7/10801Multidistance reading
    • G06K7/10811Focalisation
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B3/00Simple or compound lenses
    • G02B3/12Fluid-filled or evacuated lenses
    • G02B3/14Fluid-filled or evacuated lenses of variable focal length
    • 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
    • G06K7/10732Light sources
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K2207/00Other aspects
    • G06K2207/1013Multi-focal

Abstract

A code scanner, which illuminates a scanned code from a distance, includes a liquid lens which focuses the reflected image of the code on an image sensor. The scanner includes a range detector, preferably laser-based, which determines the distance to the scanned code, and the liquid lens is controlled to focus at the detected distance. A source of illumination is uncontrolled to maintain its intensity substantially constant, regardless of the distance of the scanned code. This can be achieved by controlling the intensity of illumination (directly), or the dispersal angle of illumination in relationship to the distance.

Description

OPTICAL CODE SCANNER WITH AUTOMATIC FOCUSING

BACKGROUND ART

The present convention relates generally to autofocus scanning systems and, more particularly, concerns code scanners capable of reading effectively over a wide range distances from a near field to a far field.

Optical scanning systems find wide application throughout industry. Barcode scanners are a common form of code scanner. Some scanners of this type are handheld and need to recognize codes on labels in a large range of sizes over a large range of distances. For example, a barcode reader should, ideally, to be able to read anything from a tiny label with a resolution of 0.127 mm at a distance of 50 mm (near field) to a huge label with a resolution of 1.4 mm at a distance of 3 m (far field). Some scanners need to recognize two-dimensional codes, which presents an even more stringent requirement.

The fundamental problem is that the scanning system must retain sharp focus over a large depth of field (DOF), the distance, included in the near to far fields. The effective DOF can be increased by a using an automatic focus or zoom focus mechanism, such as one having a voice coil motor, to operate the optics or, the like. However, they tend to have a relatively slow response (I do not think that this is true.), involve the use of moving parts (reliability issue) (If so all digital cameras and mobile phones have the same issues.), and have a relatively limited focal range (I do not think that this is true.). They are also not easily retrofitted into existing systems, since they must be introduced in the middle of the optics, requiring redesign of all the lenses.

Even if the shortcomings of autofocus mechanisms could be overcome, the achievement of an ideal DOF could not be achieved. Illumination for reading the code is provided by the scanner, and it falls off steeply with distance. Thus, an illumination which is barely sufficient in the far field would be much too bright in the near field.

Broadly, it is an object of the present invention to provide an optical code scanner which is capable of detecting a code image effectively over all distances from a near field to a far field. It is another object of the present invention to provide an optical code scanner which is capable of detecting a code image a relatively quickly, preferably in 20 ms, or less.

It is another object of the present invention to provide an optical code scanner which avoids the use of moving parts, eliminating the associated reliability issues.

It is another object of the present invention to provide an optical code scanner which has a substantially greater focus range than available optical code scanners. It is another object of the present invention to provide an optical code scanner which is easily retrofitted into existing scanning systems.

It is also an object of the present invention to provide an optical code scanner which is convenient and reliable in use, yet relatively simple and inexpensive in construction.

DISCLOSURE OF INVENTION

In accordance with one aspect of the present invention, a code scanner, which illuminates a scanned code from a distance, includes a liquid lens which focuses the reflected image of the code on an image sensor. The scanner includes a range detector, preferably laser- based, which determines the distance to the scanned code, and the liquid lens is controlled to focus at the detected distance.

In accordance with another aspect of the invention, a code scanner, which illuminates a scanned code from a distance includes a range detector, preferably laser-based, which determines the distance to the scanned code, and the source of illumination is uncontrolled to maintain its intensity substantially constant, regardless of the distance of the scanned code. This can be achieved by controlling the intensity of illumination (directly), or the dispersal angle of illumination in relationship to the distance.

BRIEF DESCRIPTION OF DRAWINGS The foregoing brief description, and other objects, features and advantages of the present invention will be understood more completely from the following detailed description of presently preferred, but nonetheless illustrative, embodiments in accordance with the present invention, with reference being had to the accompanying drawings, in which Figure 1 is schematic diagram illustrating a code scanner embodying the present invention.

BEST MODE OF CARRYING OUT THE INVENTION

Turning now to the details of the drawings, Figure 1 is schematic diagram illustrating a code scanner 10 embodying the present invention. The scanner 10 has a light source 12, which illuminates an optical code 14, such as a barcode, at a distance. The light L reflected from barcode 14 forms an image on image sensor 16, which is processed to decode the bar code 14. A liquid lens 18 is interposed in the light path L between bar code 14 and image sensor 16. Those skilled in the art will understand that this an electro optical type of device which has a optical interface between two transparent layers. Through the adjustment of an applied voltage, the shape of that interface maybe changed, changing the focal length of the lens. The distance between the lens 18 and image sensor 16 remains fixed, however, the distance to the left of lens 18 of the plain on which the lens will focus will vary with the applied voltage. It is therefore possible to focus barcodes 14 at a range of distances from image sensors 16 by simply varying a voltage that controller 20 applies to lens 18. Mechanical movement of the lens is not necessary. However, it will be appreciated that the control voltage applied to lens 18 must be correlated to the actual distance of barcode 14 from lens 18 and, therefore, from image sensor 16.

In order to ensure appropriate control of lens 18, a ranging apparatus is provided which preferably comprises a laser device and a laser detector 24. Two types of laser ranging technology are well known in the art. Pulsing technology measures the delay time between the initiation of a laser pulse and the return of its reflection. Parallax technology projects a light beam to form a spot on a target and then measures the position of the detected spot on the target. The distance of the target can be determined from the position of the detected spot. Preferably, laser device 22 and detector 24 define a parallax ranging subsystem. Laser 22 projects a light beam onto bar code 14 and detector 24 senses the position of the resulting dot and determines the distances of bar code 14. It then produces a signal representative of that distance, which is applied to controller 20. In response, controller 20 is then able to apply a voltage to lens 18 to focus it appropriately.

The output signal of detector 24 is also applied to light source 12, the intensity of which is controlled accordingly. In its simplest form, source 12 could be a ray of light emitting diodes, and the intensity could be controlled by the numbers of diodes on the array that are turned on (more simply by changing optical output power). The intensity of light source 12 could also be controlled by varying the dispersion angle of the light at the midst. Those skilled in the art will appreciate that that could be achieved mechanically by controlling the angle of vain- like devices or the like, or it can be achieved optically with a condensing lens. It would be possible to provide a plurality of condensing lens and select among them or to provide a zooming lens, possibly even a liquid lens.

In any event, through the controller focus distance and light source illumination in relationship to the distance of the bar code, it becomes possible to achieve DOF performance which approaches the ideal. Preferably, liquid lens 18 is ARCTIC-414 or ARCTIC-416 produced by Varioptic.

However, other liquid lenses may be utilized as well.

In a preferred arrangement, the laser is mounted atop of the camera module, instead of at the sides or on the bottom. Additionally, the laser should be offset from the optical axis by an amount equal to 6-15 mm. Moreover, if a LEDs are used for illumination, they should be mounted on the opposite of the module from the laser, in order to minimize the effects of reflection.

As indicated previously the present invention exhibits advantages over the prior art in that it is capable of focusing a code image more quickly; in that it avoids the use of moving parts, eliminating the associated reliability issues; in that it has a substantially greater focus range; and in that it is easily retrofitted into existing scanning systems

Although a preferred embodiment of the invention has been disclosed for a illustrative purposes, those skilled in the art will appreciate that many additions, modifications, and substitutions are possible without departing from the scope and spirit of the invention as defined by the accompanying claims.

Claims

WHAT IS CLAIMED:
1. A scanner for imaging a remote optical code comprising: an image sensor receiving an image of the code made up of light reflected therefrom; a liquid lens interposed between the code and the image sensor creating the image on the sensor and having a control input for a signal which controls focus of the lens; a range detector producing a range signal related to the distance of the optical code, a signal being applied to the control input of the lens which is related to the range signal.
2. The scanner of claim 1 wherein the range detector comprises a laser radiator projecting a beam onto the optical code to create a spot thereon and a laser detector sensing a reflection from the spot and determining the distance of the optical code.
3. The scanner of claim 2, wherein the sensor responds to the sensed position of the spot.
4. The scanner of claim 1 further comprising a source of illumination directed towards the optical code and a controller constructed to control the illumination in relationship to the range signal.
5. The scanner of claim 4 wherein the controller is constructed to control the intensity of illumination in relationship to the range signal.
6. The scanner of claim 4 wherein the controller is constructed to control the angle of disbursement of illumination in relationship to the range signal.
7. The scanner of claim 4 wherein the range detector comprises a laser radiator projecting a beam onto the optical code to create a spot thereon and a laser detector sensing a reflection from the spot and determining the distance of the optical code.
8. The scanner of claim 7, wherein the sensor responds to the sensed position of the spot.
9. A scanner for imaging a remote optical code comprising: an image sensor receiving an image of the code made up of light reflected therefrom; optics interposed between the code and the image sensor creating the image on the sensor; a range detector producing a range signal related to the distance of the optical code; a source of illumination directed towards the optical code; and a controller constructed to control the illumination in relationship to the range signal.
10. The scanner of claim 9 wherein the range detector comprises a laser radiator projecting a beam onto the optical code to create a spot thereon and a laser detector sensing a reflection from the spot and determining the distance of the optical code.
11. The scanner of claim 10, wherein the sensor responds to the sensed position of the spot.
12. The scanner of claim 10 wherein the controller is constructed to control the intensity of illumination in relationship to the range signal.
13. The scanner of claim 10 wherein the controller is constructed to control the angle of disbursement of illumination in relationship to the range signal.
14. The scanner of claim 9 wherein the controller is constructed to control the intensity of illumination in relationship to the range signal.
15. The scanner of claim 9 wherein the controller is constructed to control the angle of disbursement of illumination in relationship to the range signal.
PCT/US2007/084043 2007-11-08 2007-11-08 Optical code scanner with automatic focusing WO2009061317A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2007/084043 WO2009061317A1 (en) 2007-11-08 2007-11-08 Optical code scanner with automatic focusing

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
EP20070844971 EP2218033A4 (en) 2007-11-08 2007-11-08 Optical code scanner with automatic focusing
CN 200780101467 CN101855639A (en) 2007-11-08 2007-11-08 Optical code scanner with automatic focusing
PCT/US2007/084043 WO2009061317A1 (en) 2007-11-08 2007-11-08 Optical code scanner with automatic focusing
JP2010533055A JP2011504247A (en) 2007-11-08 2007-11-08 Autofocus with optical code scanner
US12749958 US20100294839A1 (en) 2007-11-08 2010-03-30 Optical code scanner with automatic focusing

Publications (1)

Publication Number Publication Date
WO2009061317A1 true true WO2009061317A1 (en) 2009-05-14

Family

ID=40626033

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/084043 WO2009061317A1 (en) 2007-11-08 2007-11-08 Optical code scanner with automatic focusing

Country Status (4)

Country Link
EP (1) EP2218033A4 (en)
JP (1) JP2011504247A (en)
CN (1) CN101855639A (en)
WO (1) WO2009061317A1 (en)

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WO2011146095A1 (en) * 2010-05-17 2011-11-24 Symbol Technologies, Inc. Focus adjustment with liquid crystal device in imaging scanner
JP2012068784A (en) * 2010-09-22 2012-04-05 Casio Comput Co Ltd Two-dimensional pattern reading apparatus, control method thereof and program
JP2016201116A (en) * 2016-06-22 2016-12-01 カシオ計算機株式会社 Light irradiation apparatus and program
WO2017164949A1 (en) * 2016-03-22 2017-09-28 Symbol Technologies, Llc Imaging module and reader for, and method of, variably illuminating targets to be read by image capture over a range of working distances

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JP2013025507A (en) * 2011-07-19 2013-02-04 Nippon Telegr & Teleph Corp <Ntt> Printed information reading device
US8576390B1 (en) * 2012-07-31 2013-11-05 Cognex Corporation System and method for determining and controlling focal distance in a vision system camera

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US5495096A (en) * 1991-09-20 1996-02-27 Omron Corporation Multi-focus optical device
US6505778B1 (en) * 1998-07-17 2003-01-14 Psc Scanning, Inc. Optical reader with selectable processing characteristics for reading data in multiple formats
US20070156021A1 (en) * 2005-09-14 2007-07-05 Bradford Morse Remote imaging apparatus having an adaptive lens
US7246747B2 (en) * 2000-02-28 2007-07-24 Datalogic Scanning, Inc. Multi-format bar code reader

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US5864128A (en) * 1991-10-15 1999-01-26 Geo Labs, Inc. Lens with variable focal length
EP1714231B1 (en) * 2004-01-23 2011-09-07 Intermec IP Corporation Autofocus barcode scanner and the like employing micro-fluidic lens
US20070063048A1 (en) * 2005-09-14 2007-03-22 Havens William H Data reader apparatus having an adaptive lens
EP1804100B1 (en) * 2005-12-30 2018-02-21 Datalogic IP TECH S.r.l. Device and method for focusing a laser light beam
DE202006017268U1 (en) * 2006-11-11 2008-03-27 Leuze Electronic Gmbh & Co Kg barcode scanner
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US5495096A (en) * 1991-09-20 1996-02-27 Omron Corporation Multi-focus optical device
US6505778B1 (en) * 1998-07-17 2003-01-14 Psc Scanning, Inc. Optical reader with selectable processing characteristics for reading data in multiple formats
US7246747B2 (en) * 2000-02-28 2007-07-24 Datalogic Scanning, Inc. Multi-format bar code reader
US20070156021A1 (en) * 2005-09-14 2007-07-05 Bradford Morse Remote imaging apparatus having an adaptive lens

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011146095A1 (en) * 2010-05-17 2011-11-24 Symbol Technologies, Inc. Focus adjustment with liquid crystal device in imaging scanner
US8348168B2 (en) 2010-05-17 2013-01-08 Symbol Technologies, Inc. Focus adjustment with liquid crystal device in imaging scanner
JP2012068784A (en) * 2010-09-22 2012-04-05 Casio Comput Co Ltd Two-dimensional pattern reading apparatus, control method thereof and program
WO2017164949A1 (en) * 2016-03-22 2017-09-28 Symbol Technologies, Llc Imaging module and reader for, and method of, variably illuminating targets to be read by image capture over a range of working distances
JP2016201116A (en) * 2016-06-22 2016-12-01 カシオ計算機株式会社 Light irradiation apparatus and program

Also Published As

Publication number Publication date Type
EP2218033A4 (en) 2010-12-29 application
JP2011504247A (en) 2011-02-03 application
EP2218033A1 (en) 2010-08-18 application
CN101855639A (en) 2010-10-06 application

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