Abstract:
An optical imaging system including a laser alignment system for targeting and aligning optical imaging operations. The system includes a laser configured to project two intersecting lines along an axis that inersects the optical imager at the optimal imaging distance. The lines preferably extend perpendicularly to each other and are dimensioned to correspond to the length and width of the target when the optical imager is at an optical distance from the target. A user may properly align the optical imager by viewing the lines projected onto the target and adjusting the optic imager accordingly to quickly and easily ensure proper imaging of the target.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to automated data collection systems and, more specifically, to a system and method for properly aligning an optical imager for capturing encoded information. 
         [0003]    2. Description of the Related Art 
         [0004]    In the health care industries, barcode and other symbolic data encoding systems are being used to track information, control work flow, and ensure security and safety in the workplace. In older systems, relevant information was encoded into barcodes, which are essentially graphic representation of data (alpha, numeric, or both). Barcodes encode numbers and letters into different types of linear codes, two-dimensional codes, and composite codes (a combination of linear and two-dimensional codes) that are scanned by laser based device and then interpreted to reveal the encoded information. In more recent applications, referred to as digital or optical image capture, an optical device captures a digital picture of the barcode and software in the imager orients the picture and decodes the barcode contained in the picture. As a result of the development of such optical imaging systems, information may be encoded into more sophisticated graphical images, fonts, icons and symbols, such as Aztec code, in which various symbols are assigned to represent predetermined information, such as patient medical information, medical procedures, or even pharmaceutical doses. A chart containing the symbols alongside the associated data may be provided to a medical industry practitioner, who can then scan the appropriate symbols using an optical imager to rapidly and easily record the information electronically, program medical devices, etc. 
         [0005]    While sophisticated icons and graphics may expedite the manual entry of data, many problems arise during the implementation of optical imaging systems for use in the field. For example, the space available for presentation of symbols and their associated information on user data entry pages is limited, so the symbols are often severely reduced in size and positioned in close proximity to each other to maximize the amount of information that is at the disposal of a user. As a result, the optical images used to read and recognize the symbols must be precisely aligned to properly image the symbol and improper alignment will result in ineffective recognition. 
         [0006]    Systems for optical imaging and capturing symbol based data schemes therefore often include alignment mechanism to promote proper imaging, particular by end user. For example, some conventional systems surround the imaging unit with a clear, tubular structure that must be positioned directly over the symbol to be captured and interpreted. These systems are clumsy to operate, however, and still require that the user determine whether the tube has been properly positioned over the icon. Due to the size of the optical imaging device, it may be hard for users to easily perceive whether the device is properly aligned or to do so in an expeditious manner. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    It is therefore a principal object and advantage of the present invention to provide a system and method for ensuring the proper alignment of optical imaging systems. 
         [0008]    It is an additional object and advantage of the present invention to provide a system and method for improving the accuracy of optical imaging systems. 
         [0009]    It is a further object and advantage of the present invention to provide a system and method for improving the efficiency of optical imaging systems. 
         [0010]    In accordance with the foregoing objects and advantages, the present invention provides a laser alignment system for targeting an optical imaging system, such as a handheld optical imager communicating with a host system. More particularly, the laser alignment system comprises at least one optical laser configured to project two intersecting lines along substantially the same axis as the optical path of the optical imager. The laser is preferable configured to project lines onto a target that extend perpendicularly to each other and are dimensioned to correspond to the length and width of the target when the optical imager is at an optical distance from the target. In a preferred embodiment, the projected lines comprise four segments extending outwardly from a central point, wherein adjacent segments extend perpendicular from each other, and the target comprises a symbol enclosed by a circle. A user may verify proper alignment of the optical imager by viewing the lines projected onto the target and adjust positioning of the optical imager accordingly to quickly and easily ensure proper imaging of the target. In a preferred embodiment, a user may verify proper alignment by checking that each segment is of equal length and extends from the center of the target to the line forming the circle. If the optical imager is misaligned, the segments will not be of equal length. Similarly, if the image is positioned to closely or too remotely from the target, the projected lines will not fit precisely within the target circle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a perspective view of an authentication control system according to the present invention. 
           [0013]      FIG. 2  is a schematic of an authentication control system according to the present invention. 
           [0014]      FIG. 3  is a high-level flowchart of a control process according to the present invention. 
           [0015]      FIG. 4  is a low-level flowchart of an indicia recognition process according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring now to the drawings, wherein like reference numerals refer to like parts throughout, there is seen in  FIG. 1  an optical imaging and alignment system  10  according to the present invention. System  10  generally comprises a microcontroller  12  that is interconnected to a first optical imager  14  and/or an RFID unit  16  to a host interface  18 . It should be recognized by those of skill in the art that RFID unit  16  is an optical feature not necessary to the present invention, but which may provide additional benefits. System  10  may be arranged on a single printed circuit board  22  and encased as a single unit or housing. Integration of imager  14  and RFID unit  16  through interface  18  allows for combining control of operation of both submodules, such as RFID reading and barcode, through system  10 . 
         [0017]    Referring to  FIG. 2 , optical imager  14  comprises an image engine  20  having image processing circuitry interconnected to microcontroller  12  for omni-directional optical scanning. Image engine  20  controls an image sensor  24 , such as a complementary metal oxide semiconductor (CMOS) image sensor, and is capable of capturing two-dimensional images of ID linear barcodes, 2D stacked/matrix barcodes, standard optical character recognition (OCR) fonts, Reduced Space Symbology (RSS) barcodes, and postal barcodes, as well as providing image captured images for use in a wide range of applications, such as image and shape recognition, signature capture, image capture, and non-standard optical character recognition. 
         [0018]    Imager  14  may comprise, but is not limited to, an IT4X10/80 SR/SF or IT5X10/80 series imager available from Hand Held Products, Inc. of Skaneateles Falls, N.Y. that is capable of scanning and decoding most standard barcodes including linear, stacked linear, matrix, OCR, and postal codes. Specifically, the IT5X10/80 series imager is a CMOS-based decoded output engines that can read 2D codes, and has image capture capabilities sufficient for use with system  10 . Imager  14  obtains an optical image of the field of view and, using preprogrammed algorithms in image engine  20 , deciphers the context of the image to determine the presence of any decodable barcodes, linear codes, matrix codes, and the like. Image engine  20  may be programmed to perform other image processing algorithms on the image captured by imager  14 , such as shape recognition, match filtering, and other high-level processing techniques. Alternatively, a captured image may be processed by microprocessor  12 , albeit with a decreased level of performance due to the additional communication time needed to transfer images from image engine  20  to microprocessor  12 . Imager  14  further includes an illumination source  26 , such as one or more light-emitting diodes (LEDs) of various wavelengths, i.e., colors. Those of skill in the art will instantly recognize that illumination source  26  may be provided as part of imager  14  or as a separate unit depending on the requirements of the particular application. 
         [0019]    System  10  may optionally include RFID unit  16  including an RFID transceiver  30  and associated RFID antenna  32  supporting standard RFID protocols, such as the TI Tag-it transponder protocol or ISO 15693. For these protocols, transceiver  30  operates at 13.56 MHz, and may comprise a S6700 Multi-Protocol Transceiver IC available from Texas Instruments of Dallas, Tex. Depending on the application, other frequency transceivers may be more appropriate based on target range, power availability, cost, etc. RFID unit  16  may further include a speaker or LED (not shown) for audibly indicating a successful interrogation of an RFID tag. 
         [0020]    Antenna  32  is preferably a loop antenna of various sizes and turns implemented on a printed circuit board and connected to system  10 , or a wire loop installed antenna installed directly onto system  10 . Antenna  32  may be positioned remotely, thereby reducing the footprint of system  10  using an external connector, such as a MMCX coaxial connector. RFID transceiver  30  may be programmed to interrogate passive or active tags, process signals received from such tags (e.g., analog to digital conversion), and provide the information from the tags to microcontroller  12  for further processing or transmittal to a host computer via interface  18 . 
         [0021]    Host interface  18  comprises a host transceiver  34  and a host connector  36  for interconnection to a host device  38 . Interface  18  may comprise a conventional RS232 transceiver and associated 12 pin RJ style jack. For example, an ADM202EARN available from Analog Devices, Inc. of Norwood, Mass. is a suitable RS-232/V.28 interface device having compliant levels of electromagnetic emissions and immunity. Alternatively, interface  18  may comprise other conventional buses, such as USB, IEEE 1394, 12C, SPI, or PCMCIA, or other connector styles, such as an FFC style to an embedded host or another system  10 . Interface  18  may also comprise a wireless transceiver in lieu of connector  36  for wireless communication to a host computer. A Stewart Connector Systems Inc. SS-641010S-A-NF may serve as connector  36  for mating with a Stewart Connector 937-SP-361010-031 matching connector of a host device. Host interface  18  may also comprise a Molex MX52588 connector. Regardless of the type of connector  36  used in connection with system  10 , host transceiver  34  is programmed with the applicable protocols for interfacing with a host computer, such as USB, Bluetooth(r), and IrDA protocols. Transceiver  34  may also be programmed to support both non-inverted signal sense and inverted signal sense. 
         [0022]    Microcontroller  12  comprises a conventional programmable microprocessor having on-chip peripherals, such as central processing unit, Flash EEPROM, RAM, asynchronous serial communications interface modules, serial peripheral interfaces, Inter-IC Buses, timer modules, pulse modulators with fault protection modules, pulse width modulators, analog-to-digital converters, and digital-to-analog converters. Additionally, the inclusion of a PLL circuit allows power consumption and performance to be adjusted to suit operational requirements. In addition to the I/O ports, dedicated I/O port bits may be provided. Microcontroller  12  may further include an on-chip bandgap based voltage regulator that generates an internal digital supply voltage from an external supply range. Microcontroller  12  preferably comprises a Motorola MC9S12E128. 
         [0023]    The functional integration of imager  14  and RFID unit  16  to interface  18  is accomplished by microcontroller  12 , which receives and interprets host commands, and then executes the appropriate functions by driving imager  14  and/or RFID unit  16  accordingly. For example, the operation of imager  14  and RFID unit  16  may be triggered by serial commands sent to system  10  from a host device  38 , or by a hardware button communicating directly with connector  36  or through host device  38 . Microcontroller  12  may further be programmed to execute the functions otherwise performed by one or more of image engine  20 , RFID transceiver  30 , and host transceiver  34 , thereby reducing the amount of circuitry and hardware required by system  10 . 
         [0024]    Referring to  FIG. 3 , system  10  further comprises an alignment laser assembly  40 . Laser assembly  40  preferably comprises a laser diode and associated optics. For example, laser assembly  40  may comprise a LM-761-A1 laser module available from Excel Scientech Co., Ltd. of Taiwan, R.O.C., such as that provided with some model imagers  14 . Laser assembly  40  is preferably configured to project a targeting image  42  having four segments  44  extending outwardly from a common point  46 . Preferably, segments  44  of targeting image  42  produced by laser assembly  40  are configured to be of equal length and be at right angles to each other, thereby forming cross-hairs when targeting image  42  encounters a planar surface  48 , such as a piece of paper. In addition, each segment  44  preferably has predetermined length when imager  14  is positioned at an optimum distance from surface  48  for capturing images thereof. It should be recognized by those of skill in the art that segments  44  may comprise solid lines, or lines formed from a series of dots using masking techniques. 
         [0025]    Laser assembly  40  is also configured to produce segments  44  having a predetermined relationship to a target  50  to be imaged and decoded, such as a barcode, symbol, or encoded icon, when imager  14  is positioned at a desired distance from surface  48 . Laser assembly is preferably triggered by a user prior to triggering an image capture by imager  14 . Fox example, when imager  14  is provided in a handheld unit that is manually activated, such as by a manual trigger or button, manual activation first activates laser assembly  40 . Imager  14  captures an optical image of target  50  after a predetermined delay or further manual triggering by the user. For example, manual activation may comprise the actuation of a two-stage manual trigger that, when partially activated, triggers laser assembly  40  and, when fully activated, triggers imager  14  to capture an image. Alternatively, separate triggers may be provided for laser assembly  40  and imager  14 . Preferably, a hardware trigger actuated by a user results in software commands that first activates laser assembly  40  to provide aiming for a short, predetermined time period, and then activates decoding of geometric  FIG. 52 . Thus, decoding is delayed for a short time to allow for proper orientation of the device. 
         [0026]    As seen in  FIG. 6 , imager  14  is generally aligned along axis X-X and laser assembly  40  is aligned on non-parallel axis Y-Y for projecting targeting image  42  onto target  50 , which is also within the image capture field of imager  14 . In the example above, the optimum focal distance is four inches, with laser assembly  40  configured accordingly. 
         [0027]    Targeting image  42  may also be used to determine the proper distance of imager  14  from target  50 . For example, as seen in  FIG. 5 , the length of segments  44  of targeting image  42  relative to optimum image capturing distance may be configured such that segments  44  fit exactly within geometric  FIG. 52  when imager  14  is the appropriate distance from target  50 . Thus, a user may view targeting image  42  and then move imager  14  closer or farther from target  50  depending on whether the segments extend beyond geometric  FIG. 52  or do not reach the perimeter of geometric  FIG. 52 , respectively. 
         [0028]    Referring to  FIG. 5 , system  10  further comprises the positioning of a geometric  FIG. 52 , such a circle, around target  50  to be imaged. When a user directs imager  14  at target  50 , laser assembly  40  is triggered to emit targeting image  42  onto target  50  in a predetermined relationship to geometric  FIG. 52 . As seen in  FIG. 5 , a preferred embodiment of the present invention comprises targeting image  42  as cross-hairs that are configured to fit exactly within geometric  FIG. 52 , which comprises a circle formed around target  50 . 
         [0029]    Based on the relationship between targeting image  42 , target  50 , and geometric  FIG. 52 , a user may verify that imager  14  is properly aligned to capture an image of target  50  that will optimize successful decoding of information encoded into target  50 . In the event that imager  14  is not properly aligned, a user may easily determine the best and fastest way to align imager  14  for example a successful image capture by viewing the relationship between targeting image  42 , target  50 , and geometric  FIG. 52 . For example, as seen in  FIG. 6 , the presence of unequal length segments in targeting image  42  reveal that imager  14  is tilted too far in one direction from the ideal axis X-X for proper imaging alignment and a successful read. By viewing targeting image  42  as imager  14  is realigned, a user may quickly and easily adjust imager  14  to obtain the proper location and alignment of axis X-X relative to target  50 . 
         [0030]    Targeting image  42  may comprise other shapes, such as circle having the same dimension as geometric  FIG. 52 , thereby allowing a user to properly align imager  14  by superimposing targeting image  42  onto geometric  FIG. 52 . It should thus be recognized by those of skill in the art that any combination of shapes may be used, provided that targeting image  42  and geometric  FIG. 52  are interrelated such that a user can determine the proper distance for positioning imager  14  and alignment of imager  14  relative to axis X-X.