WO2013026180A1

WO2013026180A1 - Optical code symbol reading system employing axicon-generated laser aiming beam

Info

Publication number: WO2013026180A1
Application number: PCT/CN2011/001405
Authority: WO
Inventors: Rui Hou
Original assignee: Metrologic Instruments, Inc.
Priority date: 2011-08-23
Filing date: 2011-08-23
Publication date: 2013-02-28

Abstract

Method of and apparatus for reading code symbols using an axicon-based laser pointing/aiming beam subsystem that generates and projects a cone-like visible laser pointing/aiming beam into the field of view of a digital imaging bar code symbol reader, or into the scanning field of a laser scanning bar code symbol reader.

Description

OPTICAL CODE SYMBOL READING SYSTEM EMPLOYING AXIC ON-GENERATED

LASER AIMING BEAM

BACKGROUND

Field of Disclosure

The present disclosure relates to an improved method of and apparatus for aiming at target objects when attempting to read bar code symbols presented thereon.

Brief Overview of the State of Knowledge In The Art

The need to target, indicate and/or mark the field of view (FOV) of ID and 2D image sensors within hand-held imagers has long been recognized in the industry. To a lesser degree, there has been a need to point to and aim at bar coded objects located at long distances during laser scanning operations.

In US Patent No. 4,877,949, by Danielson et al filed on August 8, 1986, an imaging-based bar code symbol reader is disclosed having a 2D image sensor with a field of view (FOV) and also a pair of LEDs mounted about a ID (i.e. linear) image sensor to project a pair of light beams through the FOV focusing optics and produce a pair of spots on a target surface supporting a ID bar code, thereby indicating the location of the FOV on the target and enable the user to align the bar code therewithin.

In US Patent No. 5,019,699, by Koenck et al filed on August 31, 1988, an imaging-based bar code symbol reader is disclosed having a 2D image sensor with a field of view (FOV) and also a set of four LEDs (each with lenses) about the periphery of a 2D (i.e. area) image sensor to project four light beams through the FOV focusing optics and produce four spots on a target surface to mark the corners of the FOV intersecting with the target, to help the user align ID and 2D bar codes therewithin in an easy manner.

In Figs. 48-50 of US Patent Nos. 5,841,121 filed November 19, 1996 and 6,681,994, filed on January 8, 2002, both by Koenck, an imaging-based bar code symbol reader is disclosed having a 2D image sensor with a field of view (FOV) and also apparatus for marking the perimeter of the FOV, using four light sources and light shaping optics (e.g. cylindrical lens).

In US Patent No. 5,378,883, by Batterman et al filed July 19, 1991, a hand-held imaging- based bar code symbol reader is disclosed having a 2D image sensor with a field of view (FOV) and also a laser light source and fixed lens to produce a spotter beam that helps the operator aim the reader at a candidate bar code symbol. As disclosed, the spotter beam is also used measure the distance to the bar code symbol during automatic focus control operations supported within the bar code symbol reader.

In US Patent No. 5,659,167, by Wang et al filed December 6, 1995, an imaging-based bar code symbol reader is disclosed comprising a 2D image sensor with a field of view (FOV), a user display for displaying a visual representation of a dataform (e.g. bar code symbol), and visual guide marks on the user display for indicating whether or not the dataform being imaged is in focus when its image is within the guide marks, and out of focus when its image is within the guide marks.

In US Patent No. 6,347,163, by Roustaei filed on May 19, 1995, a system for reading 2D images is disclosed comprising a 2D image sensor, an array of LED illumination sources, and an image framing device which uses a VLD for producing a laser beam and a light diffractive optical element for transforming the laser beam into a plurality of beamlets having a beam edge and a beamlet spacing at the 2D image, which is at least as large as the width of the 2D image.

In US Patent No. 5,783,81 1, by Feng et al filed on February 26, 1996, a portable imaging assembly is disclosed comprising a 2D image sensor with a field of view (FOV) and also a set of LEDs and a lens array which produces a cross-hair type illumination pattern in the FOV for aiming the imaging assembly at a target.

In US Patent No. 5,793,033, by Feng et al filed on March 29, 1996, a portable imaging assembly is disclosed comprising a 2D image sensor with a field of view (FOV), and a viewing assembly having a pivoting member which, when positioned a predetermined distance from the operator's eye, provides a view through its opening which corresponds to the target area (FOV) of the imaging assembly, for displaying a visual representation of a dataform (e.g. bar code symbol).

In US Patent No. 5,780,834, by Havens et al filed on May 14, 1996, a portable imaging and illumination optics assembly is disclosed having a 2D image sensor with a field of view (FOV), an array of LEDs for illumination, and an aiming or spotting light (LED) indicating the location of the FOV.

In US Patent No. 5,949,057, by Feng et al filed on January 31 , 1997, a portable imaging device is disclosed comprising a 2D image sensor with a field of view (FOV), and first and second sets of targeting LEDs and first and second targeting optics, which produces first and second illumination targeting patterns, which substantially coincide to form a single illumination targeting pattern when the imaging device is arranged at a "best focus" position.

In US Patent No. 6,060,722, by Havens et al filed on September 24, 1997, a portable imaging and illumination optics assembly is disclosed comprising a 2D image sensor with a field of view (FOV), an array of LEDs for illumination, and an aiming pattern generator including at least a point- like aiming light source and a light diffractive element for producing an aiming pattern that remains approximately coincident with the FOV of the imaging device over the range of the reader-to-target distances over which the reader is used.

In US Patent No. 6,340,114, by Correa et al filed June 12, 1998, an imaging engine is disclosed comprising a 2D image sensor with a field of view (FOV) and an aiming pattern generator using one or more laser diodes and one or more light diffractive elements (DOEs) to produce multiple aiming frames having different, partially overlapping, solid angle fields or dimensions corresponding to the different fields of view of the lens assembly employed in the imaging engine. The aiming pattern includes a centrally-located marker or cross-hair pattern. Each aiming frame consists of four corner markers, each comprising a plurality of illuminated spots, for example, two multiple spot lines intersecting at an angle of 90 degrees. However, the manufacture of DOEs is a relatively expensive part and impact the cost greatly of such aiming systems.

While progress has been made in field of view (FOV) marking, targeting and pointing art, there is still a great need in the art to provide an improved method of and apparatus for aiming at target objects when attempting to read bar code symbols presented thereon, while avoiding the shortcomings and drawbacks of prior art apparatus and methodologies.

OBJECTS AND SUMMARY

A primary object of the present disclosure is to provide an improved method of and apparatus for aiming or pointing at targets in the field of view of hand-supportable optical-type code symbol readers, while avoiding the shortcomings and drawbacks of prior art target pointing apparatus and methodologies.

Another object is to provide an optical code symbol reading system with an improved laser- based aiming/pointing beam generating subsystem employing a visible laser beam source and a rotationally symmetric prism to generate a visible cone-like laser aiming beam within the scanning or imaging field of the optical code symbol reading system.

Another object is to provide such an optical code symbol reading system, wherein the rotationally symmetric prism is realized as an axicon lens which converts a plane of collimated visible laser light into a sharp and clear aiming cone which the user can easily see as a ring-like aiming pattern projected onto a target object to be scanned or imaged.

Another object is to provide an improved laser aiming beam generating subsystem which helps the user determine the precise location of the center of the scanning field of any hand- supportable laser scanning bar code symbol reading system.

Another object is to provide an improved laser aiming beam generating subsystem which helps the user determine the precise location of the center of the field of view of any hand- supportable imaging-based bar code symbol reading system.

Further objects of the present disclosure will become more apparently understood hereinafter and in the Claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully understand the Objects, the following Detailed Description of the Illustrative Embodiments should be read in conjunction with the accompanying Drawings, wherein:

Fig. 1 is a perspective view of an illustrative embodiment of a manually-triggered hand- supportable laser scanning bar code symbol reading system, having the capacity to generate a conelike laser pointing/aiming beam within the scanning field of the system, and then read bar code symbols with a generated laser scanning beam;

Fig. 2 is a schematic block diagram describing the major system components of the laser scanning bar code symbol reading system illustrated in Fig. 1 ;

Fig. 3 is a schematic diagram of the axicon-based laser pointing subsystem employed in the system of Fig. 2;

Fig. 3A showing an optical ray-tracing diagram for the axicon element employed in the axicon-based laser pointing subsystem of Fig. 2;

Fig. 4 is a flow chart describing the primary steps carried out in the manually-triggered laser scanning bar code symbol reading system of Fig. 1, wherein upon pushing/touching the trigger button to a first position, a cone-like visible aiming beam is automatically generated to allow the user to aim at the bar code symbol to be read, and then upon pushing the trigger button to its second position, the bar code symbol is automatically laser scanned, and captured scan data processed to read the bar code symbol.;

Fig. 5 is a perspective view of a hand-supportable digital-imaging based bar code symbol reading system, having the capacity to generate a cone-like laser pointing/aiming beam within the field of view of the system, and then read bar code symbols with the FOV;

Fig. 6A is a first perspective exploded view of the digital-imaging based bar code symbol reading system depicted in Fig. 5, showing its printed circuit board assembly arranged between the front and rear portions of the system housing, with the hinged base being pivotally connected to the rear portion of the system housing by way of an axle structure;

Fig. 6B is a second perspective/exploded view of the digital-imaging based bar code symbol reading system shown in Fig. 5;

Fig. 7 is a schematic block diagram describing the major system components of the digital- imaging based bar code symbol reading system illustrated in Figs. 5, 6A and 6B; and Fig. 8 is a flow chart describing the primary steps carried out in the digital-imaging based bar code symbol reading system of Fig. 5, wherein upon pushing/depressing the trigger button to a first position, a cone-like visible aiming laser beam is automatically generated to allow the user to aim at the bar code symbol to be read, and then upon pushing/depressing the trigger button to its second position, digital image(s) of the aimed at bar code symbol are automatically captured and processed to read the bar code symbol.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Referring to the figures in the accompanying Drawings, the illustrative embodiments of the dual laser-scanning bar code symbol reading system and will be described in great detail, wherein like elements will be indicated using like reference numerals.

Laser Scanning Bar Code Symbol Reading System Employing An Axicon-Based Laser Aiming/Pointing Subsystem

Referring now to Figs. 1 through 4, the hand-supportable laser scanning bar code symbol reading system 1 will be described in detail.

As shown in Figs. 1 and 2, the manually-triggered laser scanning bar code symbol reader 100 comprises: a hand-supportable housing 102 having a head portion and a handle portion supporting the head portion; a light transmission window 103 integrated with the head portion of the housing 102; a 2-position manually-actuated trigger switch 104 integrated with the handle portion of the housing 102, for sending trigger signals to controller 150 and activating the axicon-based laser pointing/aiming subsystem 219 and the laser scanning module 105; laser scanning module 105, for repeatedly scanning, across the laser scanning field, a visible laser beam generated by a laser source 1 12 (e.g. VLD or IR LD) having optics to produce a laser scanning beam focused in the laser scanning field, in response to a first control signal generated by a system controller 150; wherein the laser scanning module 105 also includes a laser drive circuit 151 for receiving control signals from system controller 150, and in response thereto, generating and delivering laser (diode) drive current signal to the laser source 112 to produce laser scanning beams during the method of bar code symbol reading described in Fig. 4; light collection optics 106 for collecting light reflected/scattered from scanned object in the scanning field, and a photo-detector for detecting the intensity of collected light and generating an analog scan data signal corresponding to said detected light intensity during scanning operations; an analog scan data signal processor/digitizer 107 for processing the analog scan data signals and converting the processed analog scan data signals into digital scan data signals, which are then converted into digital words representative of the relative width of the bars and spaces in the scanned code symbol structure; programmed decode processor 108 for decode processing digitized data signals, and generating symbol character data representative of each bar code symbol scanned by the laser scanning beam; an input/output (I/O) communication interface module 140 for interfacing with a host communication system and transmitting symbol character data thereto via wired or wireless communication links that are supported by the symbol reader and host system; and a system controller 150 for generating the necessary control signals for controlling operations within the hand-supportable laser scanning bar code symbol reading system.

As shown in Fig. 2, the laser scanning module 105 comprises a number of subcomponents, namely: laser scanning assembly 1 10 with an electromagnetic coil 128 and rotatable scanning element (e.g. mirror) 134 supporting a lightweight reflective element (e.g. mirror) 134A; a coil drive circuit 1 1 1 for generating an electrical drive signal to drive the electromagnetic coil 128 in the laser scanning assembly 1 10; and a laser beam source 1 12 for producing a visible laser beam 1 13 A; and a beam deflecting mirror 114 for deflecting the laser beam 113A as incident beam 1 13B towards the mirror component of the laser scanning assembly 1 10, which sweeps the deflected laser beam 1 13C across the laser scanning field and a bar code symbol 16 that might be simultaneously present therein during system operation.

As shown in Fig. 2, the laser scanning module 105 is typically mounted on an optical bench, printed circuit (PC) board or other surface where the laser scanning assembly is also, and includes a coil support portion 110 for supporting the electromagnetic coil 128 (in the vicinity of the permanent magnet 135) and which is driven by a drive circuit 1 1 1 so that it generates magnetic forces on opposite poles of the permanent magnet 135, during scanning assembly operation.

Specification Of The Axicon-Based Laser Aiming/Pointing Subsystem of The Present Disclosure

In the preferred embodiment, axicon-based laser aiming/pointing subsystem 219 is mounted behind or in front of the transmission window 103. This way, a cone-like visible laser aiming/pointing beam 221 can be generated and projected into the scanning field where an object to be scanned might reside, in response to the user pulling trigger switch 104 to its first position. Detailed specifications for the axicon-based laser aiming/pointing subsystem 219 will now be described with reference to Figs. 3 and 3A.

As shown in Fig. 3, the axicon-based laser aiming/pointing subsystem 219 comprises: a laser pointing module 220; and a laser drive circuit 223 interfaced with system controller 150. As shown, the laser pointing beam (shaping) module 220 comprises: a visible laser diode (VLD) 222 for producing a visible laser beam; a light collimating lens (e.g. a simple plane-convex lens) 224 for collimating the light beam into a planar wavefront and focusing the beam to its focal point its optical axis, as shown; and an aperture stop 224A having a circular aperture with a diameter D=2R, for shaping the diameter of the laser beam to a D=2R diameter as a cone-like laser beam emanates from an axicon optical element (i.e. rotationally symmetric prism with radius R) 225, mounted within an optically assembly, along the optical axis of the coUimating lens 224, as shown. As shown in Fig. 3, the aperture stop 224A is disposed between the coUimating lens 224 and the axicon optical element 225. However, alternatively, the aperture stop 224 A can disposed after the axicon optical element 225, and before its focal point, to shape the diameter of the cone-like laser beam (i.e. D=2R) emanating from the aperture stop 224A, in such an alternative embodiment.

As shown in Fig. 3A, the plane of collimated light rays generated from coUimating lens 224 are transformed (through refraction) into a cone of light 221 which forms a cone-like laser aiming beam, beyond the depth of focus of lens 225, when projected onto an object or reference surface.

The diameter of the aimer cone, D=2R, will be proportional to the distance z from the axicon lens 225 to the observation plane (the plane where the barcode is located). Below is a geometrical model for the axicon-based laser pointing system.

The "depth of focus" of the axicon lens, L, is given by the equation:

L = R/((n-l)*a)

Also, the diameter D of the cone-like laser beam is given by the equation:

D = 2*z*tan((n-l)*a) where 2R=D is the diameter of the incident parallel beam;

where n is the refraction index of the axicon prism 225;

where (180-2a) is the cone angle of the axicon prism 225; and

where z is the distance from axicon prism 225 to the objective plane.

Generating The Cone-Like Laser Aiming Beam In Response To Triggering Events Within The Laser Scanning Bar Code Symbol Reading System Employing An Axicon-Based Laser Aiming/Pointing Subsystem

In response to a triggering event (i.e. manually pulling trigger 104 to its first position), the system controller 150 enables subsystem 219 to generate and project a cone-like visible aiming beam 221 within the laser scanning field 1 15 of the system. After the ring-like aiming pattern is aligned with the bar code symbol to be scanned, the user pulls the trigger switch 104 to its second position, whereupon the system controller 150 enables the laser scanning module 105 to generate and project a laser scanning beam through the light transmission window 103, and across the laser scanning field external to the hand-supportable housing, for scanning an object in the scanning field. The laser scanning beam is generated by laser beam source 1 12 in response to control signals generated by the system controller 150. The scanning element (i.e. mechanism) 134 repeatedly scans the selected laser beam across a code symbol residing on an object in the laser scanning field 1 15. Then, the light collection optics 106 collects light reflected/scattered from scanned code symbols on the object in the scanning field, and the photo-detector (106) automatically detects the intensity of collected light (i.e. photonic energy) and generates an analog scan data signal corresponding to the light intensity detected during scanning operations. The analog scan data signal processor/digitizer 107 processes the analog scan data signals and converts the processed analog scan data signals into digitized data signals. The programmed decode processor 108 decode processes digitized data signals, and generates symbol character data representative of each bar code symbol scanned by the laser scanning beam. Symbol character data corresponding to the bar codes read by the decoder 108, are then transmitted to the host system via the I/O communication interface 140 which may support either a wired and/or wireless communication link, well known in the art. During object detection and laser scanning operations, the system controller 150 generates the necessary control signals for controlling operations within the hand-supportable laser scanning bar code symbol reading system.

Control Operations Within The Laser Scanning Bar Code Symbol Reading System

Referring to Fig. 4, the method of reading bar code symbols and controlling operations within the laser scanning bar code reader 100 will be described in greater detail.

As indicated in Fig. 4, the process orchestrated by system controller 150 begins at the START Block. Then at Block A, the system controller 150 determines if a trigger event has occurred (i.e. whether or not trigger 104 has been manually depressed by the operator upon seeing an object in the laser scanning field and pointing the head portion of the housing towards the object).

When the trigger is pulled at Block A, the system controller 150 enables at Block B, the axicon-based laser pointing subsystem 219 to generate and project the cone-like laser pointing beam 221 into the laser scanning field 115 of the system. The projected cone-like laser pointing beam 221 allows the user to align the pointing beam with any bar code symbol that is to be laser scanned and read in an automated manner.

At Block C, the system controller determines whether or not another trigger event has occurred (e.g. trigger switch pulled to its second position) within a predetermined time period, and if not, then the system returns to Block A. When the trigger switch is pulled to its second position, at Block D, the system controller 150 then directs the laser scanning module 105 to scan the detected object with a laser beam generated by the VLD 1 12. At Block E, the decode processor 108 runs a decode algorithm on the captured scan data. If at Block F, a bar code symbol is decoded, then at Block G, the produced symbol character data is transmitted to the host system, and the system controller returns to Block A.

If, however, at Block F a bar code symbol is not decoded, then the system controller 150 determines at Block H whether or not the maximum scan attempt threshold has been reached, and if not, then the system controller 150 returns to Block D, and resumes the flow as indicated. However, if at Block H, the system controller 150 determines that the maximum scan attempt threshold has been accomplished, then the system controller 150 proceeds to Block I and sends a Failure to Decode notification to the operator and returns to Block Al .

Digital Imaging Based Bar Code Symbol Reading System Employing An Axicon-Based Laser Aiming/Pointing Subsystem

Referring now to Figs. 5 through 8, an illustrative embodiment of the hand-supportable digital-imaging bar code symbol reading system 1 will be described in detail.

As shown in Figs. 5, 6A, 6B and 7, the digital-imaging bar code symbol reading system 300 comprises: a hand-supportable housing 302 having (i) a front housing portion 302B with a window aperture 360 and an imaging window panel 303 installed therein; and (ii) a rear housing portion 302 A. As shown, a single PC board based optical bench 308 (having optical subassemblies mounted thereon) is supported between the front and rear housing portions 302 A and 303B which, when brought together, form an assembled unit. A base portion 304 is connected to the assembled unit by way of a pivot axle structure 331 that passes through the bottom portion of the imager housing and the base portion so that the hand-supportable housing and base portion are able to rotate relative to each other. The host/imager interface cable 310 passes through a port 332 formed in the rear of the rear housing portion, and interfaces with connectors mounted on the PC board 308.

As shown in Fig. 5, the digital-imaging based code symbol reading system 300 comprises a number of subsystem components, namely: a digital image formation and detection (i.e. camera) subsystem 321 having image formation (camera) optics 334 for producing a field of view (FOV) upon an object to be imaged and a CMOS or like area-type image detection array 335 for detecting imaged light reflected off the object during illumination operations in an image capture mode in which at least a plurality of rows of pixels on the image detection array are enabled; a LED-based illumination subsystem 322 employing a single LED illumination array 323 comprising visible and invisible (infrared) LEDs, alternatively interspaced along a linear dimension, in the illustrative embodiment (although other arrangements are possible); a narrow-band transmission-type optical filter 340, realized within the hand-supportable and detected by the image detection array 335, for transmitting illumination reflected from the illuminated object, while all other components of ambient light are substantially rejected; an object targeting illumination subsystem 331 as described hereinabove; an IR-based object detection subsystem 320 for producing an IR-based object detection field 332 within the FOV of the image formation and detection subsystem 321 ; an automatic light exposure measurement and illumination control subsystem 324 for controlling the operation of the LED-based illumination subsystem 322 including the operation of said visible and invisible illumination arrays within the illumination subsystem 322; an image capturing and buffering subsystem 325 for capturing and buffering 2-D images detected by the image formation and detection subsystem 321 : a digital image processing subsystem 326 for processing 2D digital images captured and buffered by the image capturing and buffering subsystem 325 and reading ID and/or 2D bar code symbols represented therein; and an input/output subsystem 327 for outputting processed image data and the like to an external host system or other information receiving or responding device; and a system control subsystem 330 integrated with the subsystems above, for controlling and/or coordinating these subsystems during system operation.

The primary function of the axicon-based laser pointing subsystem 219 is to automatically generate and project a visible con-like laser pointing/aiming beam 221 across the central extent of the FOV of the system in response to either (i) the automatic detection of an object during hand-held imaging modes of system operation, or (ii) manual detection of an object by an operator when s/he manually actuates the manual actuatable trigger switch 305 integrated with housing 302.

To implement the axicon-based laser pointing subsystem 219 in system 300, the OCS assembly 378 also comprises a fourth support structure for supporting beam folding mirror above laser pointing beam module 220, shown in FIG. 3. In turn, module 220 is mounted on PC board 308, adjacent digital image detection array 335 and arranged to generate cone-line visible laser aiming beam 221 generated from module 220 and projected off the second FOV folding 375 and out the imaging window 303 into the FOV 313.

The primary function of the object motion detection and analysis subsystem 320 is to automatically produce an object detection field 32 within the FOV 33 of the image formation and detection subsystem 21, to detect the presence of an object within predetermined regions of the object detection field 332, as well as motion and velocity information about the object therewithin, and to generate control signals which are supplied to the system control subsystem 330 for indicating when and where an object is detected within the object detection field of the system.

As shown in Fig. 6B, IR LED 390A and IR photodiode 390B are supported in the central lower portion of the optically-opaque structure 379, below the linear array of visible LEDs 323. The IR LED 390A and IR photodiode 390B are used to implement the automatic IR-based object motion detection and analysis subsystem 320, which can be used when the system is operated in its automatic mode of system operation. The image formation and detection (i.e. camera) subsystem 321 includes image formation (camera) optics 334 for providing a field of view (FOV) 313 upon an object to be imaged and a CMOS area-type image detection array 335 for detecting imaged light reflected off the object during illumination and image acquisition/capture operations.

The primary function of the LED-based illumination subsystem 322 is to produce a visible wide-area illumination field 314 from the visible LED array 323 when subsystem 322 is operating in its visible illumination and imaging mode of operation. Notably, field of illumination 314 has a narrow optical-bandwidth and is spatially confined within the FOV of the image formation and detection subsystem 321 during illumination and imaging. This arrangement is designed to ensure that only narrow-band illumination transmitted from the illumination subsystem 322, and reflected from the illuminated object, is ultimately transmitted through a narrow-band transmission-type optical filter subsystem 340 within the system and reaches the CMOS area-type image detection array 335 for detection and processing, whereas all other components of ambient light collected by the light collection optics are substantially rejected at the image detection array 335, thereby providing improved SNR, thus improving the performance of the system.

The narrow-band transmission-type optical filter subsystem 340 is realized by (1) a high-pass (i.e. red-wavelength reflecting) filter element embodied within the imaging window 303, and (2) a low-pass filter element mounted either before the CMOS area-type image detection array 335 or anywhere after beyond the high-pass filter element, including being realized as a dichroic mirror film supported on at least one of the FOV folding mirrors 374 and 375, shown in Figs. 6A and 6B.

As shown in Fig. 6B, the single linear array of alternatively spaced visible (and IR) LEDs 323 is aligned with an illumination- focusing lens structure 130 embodied or integrated within the upper edge of the imaging window 303. Also, the light transmission aperture 360 formed in the PC board 308 is spatially aligned within the imaging window 303 formed in the front housing portion 302A. The function of illumination-focusing lens structure 130 is to focus illumination from the single linear array of LEDs 323, and to uniformly illuminate objects located anywhere within the working distance of the FOV of the system.

As shown in Figs. 6B, an optically-opaque light ray containing structure 333 is mounted to the front surface of the PC board 308, about the linear array of LEDs 323. The function of the optically-opaque light ray containing structure 333 is to prevent transmission of light rays from the LEDs to any surface other than the rear input surface of the illumination-focusing lens panel 303, which uniformly illuminates the entire FOV of the system over its working range. When the front and rear housing panels 302B and 302A are joined together, with the PC board 308 disposed therebetween, the illumination-focusing lens panel 303 sits within slanted cut-aways formed in the top surface of the side panels, and illumination rays produced from the linear array of LEDs 323 are either directed through the rear surface of the illumination-focusing lens panel 303 or absorbed by the black colored interior surface of the structure 333.

As shown in Figs. 6A and 6B the optical component support (OCS) assembly 378 comprises: a first inclined panel for supporting the FOV folding mirror 374 above the FOV forming optics, and a second inclined panel for supporting the second FOV folding mirror 375 above the light transmission aperture 360. With this arrangement, the FOV employed in the image formation and detection subsystem 321, and originating from optics supported on the rear side of the PC board, is folded twice, in space, and then projected through the light transmission aperture and out of the imaging window of the system.

The automatic light exposure measurement and illumination control subsystem 324 performs two primary functions: (1) to measure, in real-time, the power density [joules/cm] of photonic energy (i.e. light) collected by the optics of the system at about its image detection array 335, and to generate auto-exposure control signals indicating the amount of exposure required for good image formation and detection; and (2) in combination with the illumination array selection control signal provided by the system control subsystem 330, to automatically drive and control the output power of the LED array 323, employed in the illumination subsystem 322, so that objects within the FOV of the system are optimally exposed to LED-based illumination, as determined by the system control subsystem 330, and optimal images are formed and detected at the image detection array 335. The OCS assembly 378 also comprises a third support panel for supporting the parabolic light collection mirror segment employed in the automatic exposure measurement and illumination control subsystem 324. Using this mirror, a narrow light collecting FOV is projected out into a central portion of the wide-area FOV 333 of the image formation and detection subsystem 321 and focuses collected light onto photo-detector, which is operated independently from the area-type image sensing array, schematically depicted in Fig. 7 by reference numeral 35.

The primary function of the image capturing and buffering subsystem 325 is (1) to detect the entire 2-D image focused onto the 2D image detection array 335 by the image formation optics 334 of the system, (2) to generate a frame of digital pixel data for either a selected region of interest of the captured image frame, or for the entire detected image, and then (3) to buffer each frame of image data as it is captured. Notably, in the illustrative embodiment, the system has both single-shot and video modes of imaging. In the single shot mode, a single 2D image frame is captured during each image capture and processing cycle, or during a particular stage of a processing cycle. In the video mode of imaging, the system continuously captures frames of digital images of objects in the FOV. These modes are specified in further detail in US Patent Application Publication No. US20080314985 Al, incorporated herein by reference in its entirety. The primary function of the digital image processing subsystem 326 is to process digital images captured and buffered by the image capturing and buffering subsystem 325, under the control of the system control subsystem 330. Such image processing operations include the practice of image-based bar code decoding methods, as described in U.S. Patent No. 7,128,266, incorporated herein by reference.

The primary function of the input/output subsystem 327 is to support universal, standard and/or proprietary data communication interfaces with external host systems and devices, and output processed image data and the like to such external host systems or devices by way of such interfaces. Examples of such interfaces, and technology for implementing the same, are given in US Patent Nos. 6,619,549 and 6,619,549, incorporated herein by reference in their entirety.

The primary function of the system control subsystem 330 is to provide some predetermined degree of control, coordination and/or management signaling services to each subsystem component integrated within the system, as shown, while carrying out the bar code symbol reading method described in Fig. 8. While this subsystem can be implemented by a programmed microprocessor, in the preferred embodiments, this subsystem is implemented by the three-tier software architecture supported on micro-computing platform as described in U.S. Patent No. 7,128,266, and elsewhere hereinafter.

The primary function of the manually-activatable two-position trigger switch 305 integrated with the housing is to enable the user, during a manually-triggered mode of operation, to generate a first control activation signal (i.e. trigger event signal) upon manually depressing the same to its first position (i.e. causing a first trigger event), and activate the laser pointing subsystem 219. Also when depressed to its second position, it generates a second control activation signal which activates illumination and imaging operations, during the manual mode of system operation.

The primary function of the system configuration parameter table 329 in system memory is to store (in non-volatile/persistent memory) a set of system configuration and control parameters (i.e. SCPs) for each of the available features and functionalities, and programmable modes of supported system operation, and which can be automatically read and used by the system control subsystem 330 as required during its complex operations. Notably, such SCPs can be dynamically managed as taught in great detail in copending US Publication No. US20080314985 Al , incorporated herein by reference.

Control Operations Within The Digital Imaging Bar Code Symbol Reading System

In general, hand-supportable digital imaging system 300 supports both manually-triggered and automatically-triggered modes of operation, and the method of bar code symbol reading described below can be practiced using either of these triggering techniques. However, for purposes of illustration, the manually-triggered mode of system operation will be specified in detail with reference to FIG. 8.

As indicated at Block A in Fig. 8, the control subsystem 330 determines if an object has been detected in the field of view (FOV). When the system is operating in its manually-triggered mode, this operation can be achieved by the user pulling the manually pulling trigger switch 305 to its first position. When the system is operating in its automatically-triggered mode of operation, this operation can be achieved by the object detection subsystem automatically detecting the presence of an object within the field of view (FOV) of the system. In the event that an object is detected, then at Block B, the system controller enables the laser pointing subsystem 219 to generate a cone-like laser pointing/aiming beam which is projected into the FOV of the system.

At Block C, the system control subsystem 330 determines whether or not a trigger event has occurred (e.g. the trigger switch is pulled to its second position) within a predetermined time period. If not, then the system returns to Block A, as shown. If a trigger event is detected at Block C, then the system controller enables, at Block D, the image formation and detection subsystem to detect and capture a digital image of the object in the FOV, using a field of visible LED-based illumination generated by illumination subsystem 322. At this stage, the object might bear a bar code symbol within the FOV of the system.

At Block E, digital image subsystem 326 runs an image-based decode algorithm on the captured digital image, and if at Block F, a bar code symbol graphically represented in the digital image is decodable. Then, at Block F, the bar code symbol is decoded and the symbol character data is transmitted from the I/O subsystem 327 to the host system. If, however, at Block F a bar code symbol is not decodable in the digital image, then control subsystem 330 determines at Block H whether or not the maximum scan attempt threshold has been accomplished, and if not, then the system controller returns to Block D, and resumes the flow as indicated. However, if at Block H, control subsystem 330 determines that the maximum scan attempt threshold has been reached, then control subsystem 330 proceeds to Block I and sends a failure to decode notification message at Block I and returns to Block A, as shown.

At Block F in Fig. 8, one or more code symbol are decoded within the digital image, then at Block G the symbol character data produced is transmitted to the host system 9, and system control returns to Block A, as indicated in Fig. 8. If, however, at Block F, no bar code symbol is decoded, then control subsystem 330 determines whether or not the maximum scan attempt threshold (i.e. how many attempts to decode are permitted) has been reached or attained. When the maximum number of attempts to decode has been reached at Block K, then system controller sends a failure to decode notification to the operator, and the system returns to Block B, as shown in Fig. 8. Some Modifications Which Readily Come To Mind

While the illustrative embodiments disclose the use of a ID laser scanning module to detect scan bar code symbols on objects, it is understood that a 2D or raster-type laser scanning module can be used as well, to scan ID bar code symbols, 2D stacked linear bar code symbols, and 2D matrix code symbols, and generate scan data signals for decoding processing.

While various hand-supportable optical code symbol reading systems have been illustrated, it is understood that these laser scanning systems can be packaged in modular compact housings and mounted in fixed application environments, such as on counter-top surfaces, on wall surfaces, and on transportable machines such as forklifts, where there is a need to scan code symbols on objects (e.g. boxes) that might be located anywhere within a large scanning range (e.g. up to 20+ feet away from the scanning system). In such fixed mounted applications, the trigger signal can be generated by manual switches located a remote location (e.g. within the forklift cab near the driver) or anywhere not located on the housing of the system.

Also, the illustrative embodiments have been described in connection with various types of code symbol reading applications involving 1-D and 2-D bar code structures (e.g. ID bar code symbols, 2D stacked linear bar code symbols, and 2D matrix code symbols). However, the methods and apparatus can be used to read (i.e. recognize) any machine-readable indicia, dataform, or graphically-encoded form of intelligence, including, but not limited to bar code symbol structures, alphanumeric character recognition strings, handwriting, and diverse dataforms currently known in the art or to be developed in the future. Hereinafter, the term "code symbol" shall be deemed to include all such information carrying structures and other forms of graphically-encoded intelligence.

It is understood that the digital-imaging based bar code symbol reading system of the illustrative embodiments may be modified in a variety of ways which will become readily apparent to those skilled in the art of having the benefit of the novel teachings disclosed herein. All such modifications and variations of the illustrative embodiments thereof shall be deemed to be within the scope of the Claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1. A laser scanning code symbol reading system for reading code symbols comprising:

a housing with a light transmission window;

a laser scanning module, disposed in said housing, for scanning a laser beam across a laser scanning field defined external to said light transmission window,

wherein said laser scanning module is responsive to one or more control signals generated by a system controller and includes

(i) a laser drive module for driving a laser source to produce laser beam focused within said laser scanning field in response to receiving said one or more control signals from said system controller, and

(ii) a laser scanning mechanism for scanning said laser beam across said laser scanning field, and a code symbol on an object in said laser scanning field;

a triggering subsystem, disposed within said housing, for generating triggering event in response to the presence of an object present in said laser scanning field;

an axicon-based laser pointing beam generating subsystem, disposed within said housing, for generating and projecting a cone-like laser pointing beam within said laser scanning field;

light collection optics, disposed in said housing, for collecting light reflected/scattered from scanned object in said laser scanning field;

a photo-detector, disposed in said housing, for detecting the intensity of collected light from said code symbols, and generating an analog scan data signal corresponding to said detected light intensity during laser scanning operations;

an analog scan data signal processor, disposed in said housing, for processing said analog scan data signals and converting the processed analog scan data signals into digitized data signals; a programmed decode processor, disposed in said housing, for decode processing said digitized data signals, and generating symbol character data representative of each code symbol scanned by said laser beam; and

an input/output (I/O) communication interface, disposed in said housing, for interfacing with a host system and transmitting symbol character data to said host system, via a communication link, supported by said laser scanning code symbol reading system and said host system;

said system controller, responsive to said triggering event, for controlling operations within said laser scanning bar code symbol reading system;

wherein when said system controller detects said triggering events, said system controller generates said one or more control signals causing (i)) said axicon-based laser pointing beam generating subsystem to generate and project a cone-like laser pointing beam within said laser scanning field, (ii) said laser source to generate said laser beam and (iii) said laser scanning mechanism to scan said laser beam across a code symbol on an object in said laser scanning field during laser scanning operations so as to generate an analog scan data signal which is processed and converted into a digitized data signal, which is then decoded processed in effort to read said code symbol on said object.

2. The laser scanning code symbol reading system of Claim 1, wherein said axicon-based laser pointing beam generating subsystem comprises:

a first laser source for producing a visible laser bean;

a light collimating lens for receiving said laser beam from said first laser source and producing a collimated laser beam;

an aperture stop disposed after said light collimating lens, and having a circular aperture for shaping the cross-sectional dimensions of said collimated laser beam; and

an axicon prism for receiving the collimated laser beam, and producing said cone-like visible laser pointing beam in said laser scanning field.

3. The laser scanning code symbol reading system of Claim 2, wherein said axicon-based laser pointing beam generating subsystem further comprises a first laser drive circuit for driving said first laser source.

4. The laser scanning code symbol reading system of Claim 3, wherein said first laser source comprises a first visible laser diode (VLD).

5. The laser scanning code symbol reading system of Claim 1, wherein said triggering subsystem comprises a manually-actuated trigger integrated with said housing for generating said object detection upon the user pulling said trigger switch to a particular position.

6. The laser scanning code symbol reading system of Claim 1 , wherein said axicon prism is a rotationally symmetric prism.

7. The laser scanning code symbol reading system of Claim 1, wherein said code symbols are symbols selected from the group consisting of ID bar code symbols, 2D stacked linear bar code symbols and 2D matrix code symbols.

8. The laser scanning code symbol system of Claim 1, wherein said communication link is either a wired or wireless communication link.

9. The laser scanning code symbol system of Claim 1, wherein the laser source in said laser drive module comprises a second VLD.

10. The laser scanning code symbol reading system of Claim 1, wherein said housing comprises a hand-supportable housing.

1 1. A digital-imaging code symbol reading system comprising:

a housing having a light transmission aperture;

an image formation and detection subsystem, disposed in said housing, having image formation optics for producing and projecting a field of view (FOV) through said light transmission aperture and onto an area-type image detection array for detecting one or more digital images of an object within said FOV supporting one or more code symbols, during object illumination and imaging operations;

an illumination subsystem, disposed in said housing, including an illumination array for producing a field of illumination within said FOV, and illuminating a code symbol on said object detected in said FOV, so that said illumination reflects off said object and is transmitted back through said light transmission aperture and onto said image detection array to form said digital image of said code symbol;

an axicon-based laser aiming beam generating subsystem, disposed within said housing, for generating a cone-like visible laser pointing beam within said FOV;

an image capturing and buffering subsystem, disposed in said housing, for capturing and buffering digital images of code symbols detected by said image formation and detection subsystem; a digital image processing subsystem, disposed in said housing, for processing said one or more digital images of code symbols captured and buffered by said image capturing and buffering subsystem and reading code symbols represented in said digital images;

an input/output subsystem, disposed in said housing, for outputting processed image data to an external host system or other information receiving or responding device; and

said system control subsystem, disposed in said housing, and responsive to a first triggering event to initiate laser pointing operations, and a second triggering event to initiate object illumination and imaging operations within said digital-imaging code symbol reading system, and controlling and/or coordinating said subsystems within said digital-imaging code symbol reading system, during object illumination and imaging operations; wherein upon detecting said first triggering event, said system controller generates said first control signal, and in response thereto, said axicon-based laser aiming beam generating subsystem generates and projects a cone-like visible laser pointing beam within said FOV and

wherein upon detecting said second triggering event, said system controller generates said second control signal, and in response thereto, said illumination subsystem generates said field of illumination within said FOV, and illuminates any code symbol on said object detected in said FOV, so that said illumination reflects off said code symbol and is transmitted back through said light transmission aperture and onto said image detection array to form said digital image of said code symbol, and thereafter said digital image is decoded processed by said digital image processing subsystem in effort to read said code symbol on said object.

12. The digital-imaging code symbol reading system of Claim 1 1, wherein said an axicon-based laser aiming beam generating subsystem comprises a manual trigger switch for generating said first and second triggering events whenever the operator manually actuates said manual trigger switch.

13. The digital-imaging code symbol reading system of Claim 11, which further comprises an illumination control subsystem, disposed in said housing, for controlling the operation of said illumination arrays within said illumination subsystem.

14. The digital-imaging based code symbol reading system of Claim 1 1, wherein said illumination array comprises an array of visible LEDs.

15. The digital-imaging code symbol reading system of Claim 1 1, wherein said code symbols are symbols selected from the group consisting of ID bar code symbols, 2D bar code symbols and data- matrix type code symbols.

16. The digital-imaging code symbol reading system of Claim 11, wherein said axicon-based laser pointing beam generating subsystem comprises a laser source for producing a visible laser bean; a light collimating lens for receiving said laser beam from said laser source and producing a collimated laser beam; an aperture stop with a circular aperture, disposed after said light collimating lens to as to shape the cross-sectional dimensions of said collimated laser beam; and an axicon prism for receiving the collimated laser beam, and producing said cone-like visible laser pointing beam in said laser scanning field.

17. The digital-imaging code symbol reading system of Claim 16, wherein said axicon-based laser pointing beam generating subsystem further comprises a laser drive circuit for driving said laser source.

18. The digital-imaging code symbol reading system of Claim 16, wherein said laser source comprises a visible laser diode (VLD).

19. The digital-imaging code symbol reading system of Claim 1 1, wherein said triggering subsystem comprises a manually-actuated trigger integrated with said housing for generating said object detection upon the user pulling said trigger switch to a particular position.

20. The digital-imaging code symbol reading system of Claim 1 1 , wherein said axicon prism is a rotationally symmetric prism.

21. The digital-imaging code symbol reading system of Claim 11, wherein said housing comprises a hand-supportable housing.

22. An optical code symbol reading system comprising:

a housing with a light transmission window;

an axicon-based laser pointing beam generating subsystem, disposed within said housing, for generating and projecting a cone-like laser pointing beam into a code reading field defined external to said housing, in response to a first triggering event;

an optical code symbol scanning subsystem, disposed in said housing, for reading an optical code located within said code reading field, and generating symbol character data representative of said read code symbol, in response to a second triggering event;

an input/output (I/O) communication interface, disposed in said housing, for interfacing with a host system and transmitting symbol character data to said host system, via a communication link, supported by said optical code symbol reading system and said host system;

said system controller, responsive to said first and second triggering events, for controlling operations within said optical code symbol reading system;

wherein when said system controller detects said first triggering event, said system controller generates said one or more control signals causing said axicon-based laser pointing beam generating subsystem to generate and project a cone-like laser pointing beam within said code reading field for alignment with a code symbol on an object located within said code reading field; and wherein when said system controller detects said second triggering event, said system controller generates said one or more control signals causing said optical code symbol reading subsystem optically reading the code symbol on said object in said code reading field.

23. The optical code symbol reading system of Claim 22, wherein said axicon-based laser pointing beam generating subsystem comprises:

a laser source for producing a visible laser bean;

a light collimating lens for receiving said laser beam from said laser source and producing a collimated laser beam;

an axicon prism for receiving the collimated laser beam, and producing said cone-like visible laser pointing beam in said code reading field.

24. The optical code symbol reading system of Claim 22, wherein said housing is a hand-supportable housing.

25. The optical code symbol reading system of Claim 22, wherein said code symbol is selected from the group consisting of ID bar code symbols, 2D stacked bar code symbols and datamatrix code symbols.

26. The optical code symbol reading system of Claim 22, wherein said optical code symbol reading subsystem is selected from a laser scanning code symbol subsystem and a digital imaging code symbol reading subsystem.