Abstract:
A data transfer system includes a radio frequency identification (RFID) reader having a radio frequency transmitter and receiver and a laser. The data transfer system also includes a RFID tag on a container which has a first photosensitive device coupled to an electronic circuit in the tag which is in a first state when light from the laser is not striking the photosensitive device and in a second state when light from the laser is striking the photosensitive device such that the RFID tag transmits a signal only when a light beam from the laser is striking the photosensitive device. The tag may be passive, semi-passive (battery assisted passive-BAP), or active. If the tag is BAP then the laser light causes the tag to wake up so that it can respond to the RF signal from a RFID reader. The radio frequency transmitter provides power to the RFID tag sufficient to transmit a signal to the receiver which can be decoded by the RFID reader when the RFID reader is 40 feet or more away from the RFID tag.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to Radio Frequency Identification (RFID), and more particularly to long range selective RFID using laser photodetection wakeup 
       BACKGROUND OF THE INVENTION 
       [0002]    In the Automatic Identification and Data Collection (AIDC) industry long range barcode reading is generally achieved using laser scanning or 2D imaging. Both methods have drawbacks, primarily due to poor signal to noise ratio of the detected signal. For example, when using a laser detector, the beam must be focused over a long distance to ensure that a barcode can be read. 
         [0003]    RFID is not typically used in these applications because RFID is non-directional, so targeting a specific item to be read is difficult in an environment when there may be many RFID tags essentially co-located. 
         [0004]    In order to allow the encoding of larger amounts of data in a single bar code symbol, a number of 1D stacked bar code symbologies have been developed which partition encoded data into multiple rows, each including a respective 1D bar code pattern, all or most all of which must be scanned and decoded, then linked together to form a complete message. Scanning still requires relatively higher resolution in one dimension only, but multiple linear scans are needed to read the whole symbol. 
         [0005]    A class of bar code symbologies known as two dimensional (2D) matrix symbologies have been developed which offer orientation-free scanning and greater data densities and capacities than 1D symbologies. 2D matrix codes encode data as dark or light data elements within a regular polygonal matrix, accompanied by graphical finder, orientation and reference structures. 
         [0006]    Conventionally, a reader, whether portable or otherwise, may include a central processor which directly controls the operations of the various electrical components housed within the bar code reader. For example, the central processor controls detection of keyboard entries, display features, trigger detection, and bar code read and decode functionality. 
         [0007]    Efforts regarding such systems have led to continuing developments to improve their versatility, practicality and efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The aforementioned and other features, characteristics, advantages, and the invention in general will be better understood from the following more detailed description taken in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1  is a perspective view of an indicia reader in accordance with at least one embodiment of the present invention; 
           [0010]      FIG. 2  is a partial block diagram of the indicia reader of  FIG. 1 ; 
           [0011]      FIG. 3  is a diagrammatical cross section of the indicia reader shown in  FIG. 1 ; 
           [0012]      FIGS. 4A ,  4 B,  4 C, and  4 D are combination top views and circuit diagrams of three embodiments of RFID tags which may be used with the indicia reader shown in  FIG. 1 ; and 
           [0013]      FIG. 5  shows stacks of containers, each of which has the RFID tag shown in  FIG. 2 . 
       
    
    
       [0014]    It will be appreciated that for purposes of clarity and where deemed appropriate, reference numerals have been repeated in the figures to indicate corresponding features. Also, the relative size of various objects in the drawings has in some cases been distorted to more clearly show the invention. 
       DETAILED DESCRIPTION 
       [0015]    Reference will now be made to exemplary embodiments of the invention which are illustrated in the accompanying drawings. This invention, however, may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these representative embodiments are described in detail so that this disclosure will be thorough and complete, and will fully convey the scope, structure, operation, functionality, and potential of applicability of the invention to those skilled in the art. 
         [0016]    Referring to  FIG. 1 , an exemplary hand held indicia reading device  100  which may be a portable data terminal (PDT) (referred to as “PDT  100 ”) has a case  105 , a display  1094  under a touch screen  1095 , and a keypad  1090 . The keypad  1090  includes a scan button  1050  and pointer controller keys  1060 . The touch screen  1095  and keypad  1090  provide inputs to control the operation of the electronics and imaging assembly inside the case  105  of the PDT  100 . 
         [0017]    A block diagram of the PDT  100 , incorporating a laser  1200  which operates in conjunction with a RFID reader unit  1250  according to an embodiment of the invention, is shown in  FIG. 2 . By operation of a processor IC chip  1030 , PDT  100  receives and processes various inputs from the RFID reader unit  1250  and an imaging module  1140 , and controls various outputs such as the output of various collected transaction data to the display  1094  and to other terminals via wireless transmission modules (not shown). In the embodiment of  FIG. 2 , processor IC chip  1030  includes a central processing unit or CPU  1005 . In addition to the CPU  1005  memory  1020  may be incorporated partially or entirely in processor IC chip  1030  and partially or entirely in a plurality of memory IC chips such as EPROM IC chip  1022 , RAM IC chip  1021 , and flash IC chip  1023 . EPROM IC chip  1022 , RAM IC chip  1021 , and flash IC chip  1023  or other nonvolatile storage devices may be in communication with microprocessor IC chip  1030  via system bus  1045 . Processor IC chip  1030  operates in accordance with an Operating System (OS) which is typically loaded into RAM  1021  when data collection device  100  is booted up. The device&#39;s operating system enables processor IC chip  1030  to recognize input from user input interface components, e.g., scan button  1050 , keyboard/keypad  1090 , and touch screen  1095 , to send output to output interfaces, e.g., display  1094 , to schedule tasks, to manage files and directories and to control other components such as input/output devices. Examples of suitable operating systems for PDT  100  include WINDOWS XP, LINUX, WINDOWS CE, OSX. 
         [0018]    PDT  100  may include a graphical user interface (“GUI”) which may include a pointer. The pointer is moved by an operator using the pointer controller keys  1060  to select between various displayed (sometimes referred to as “virtual”) control buttons displayed on display  1094 . Virtual control buttons may also be displayed for selecting between various menu options. PDT  100  can be configured so that displayed menu options are selected by physically depressing a displayed icon or text, with use of a finger or stylus, on the touch screen  1095 . 
         [0019]    The RFID reader unit  1250  shown in  FIG. 2  includes an RF oscillator and receiver section  1252  and a data decode processing circuit  1254 . The RFID reader unit  1250  may be configured to read RF encoded data from a RFID tag, such as tag  1260 , which may be disposed on an container  1202 . Where RFID reader unit  1250  is configured to read RF encoded data from a RFID tag  1260 , RF oscillator and receiver circuit  1252  transmits a carrier signal from antenna  1255  to tag  1260 . RFID tag  1260  converts the carrier energy to a DC voltage to power the tag  1260  and a transponder in tag  1260  is actuated to transmit a radio signal representing the encoded tag data. RF oscillator and receiver circuit  1252 , in turn, receives the radio signal from the tag and converts the data into a digital format. Data decode processing circuit  1254 , typically including a low cost microcontroller IC chip, decodes the received radio signal information received by RF oscillator and receiver circuit  1252  to decode the encoded identification data originally encoded into RFID tag  1260 . The RFID tag  1210  may be passive (without a battery in the tag) or semi-passive or battery assisted passive (with a battery in the tag) or another class of EPCglobal tags. As used herein, the concept of transmissions from an RFID tag includes passive transmission by, for example, modulated backscattering of the RF signal from an RFID reader. 
         [0020]    The RFID tag  1260  contains a transparent window  1262  for receiving light from the laser  1200 . The light from the laser  1200  is operated in conjunction with the RF oscillator and receiver  1252  such that light from the laser  1200  enables the RFID tag  1260  when the laser light illuminates circuitry within the laser tag  1260  as more fully explained below. 
         [0021]    PDT  100  as shown in  FIG. 2  may also include an imaging assembly  1140 , which includes image sensor chip  58 , illumination subsystem  6316 , aiming subsystem  6618 , imaging optics  61 , and a field programmable gate array (“FPGA”)  1180 . As shown in  FIG. 2 , illumination configuration or subsystem  6316  projects an illumination pattern  6390  onto container  1202 , while aiming configuration or subsystem  6618  projects an aiming pattern  6392  onto container  1202 . Imaging optics  61  focuses an image onto an active surface of image sensor chip  58  which also may include image sensor control circuitry, image signal conditioning circuitry, and an analog-to-digital converter. Operating under the control of processor IC chip  1030 , FPGA  1180  manages the capture of image data into RAM  1021 . 
         [0022]    When trigger button  1050  is actuated with PDT  100  in a bar code decode mode of operation, processor IC chip  1030  automatically sends appropriate control signals to image sensor chip  58 . Image sensor chip  58  in response thereto automatically exposes photosensitive pixels of image sensor chip  58  to light and generates image signals. The image signals are thereafter automatically converted into digital values by an analog-to-digital converter. The digital values are received by FPGA  1180  and transferred into RAM  1021  to capture an electronic image representation of container  1202  carrying indicia, such as a bar code symbol  1204 . In accordance with a bar code decoding program stored in ROM  1022 , processor IC chip  1030  may attempt to decode a bar code symbol represented in the captured electronic image representation. The capture of image data and decoding of image data occur automatically in response to a trigger signal being generated. A trigger signal can be generated when trigger  1050  is actuated. Processor IC chip  1030  may be configured to continuously capture image data and to attempt to decode bar code symbols represented therein as long as trigger  1050  is actuated 
         [0023]      FIG. 3  is a diagrammatical cross section of the PDT  100 . As shown in  FIG. 3  the laser  1200  projects the laser beam from the front end of the PDT  100 . The RFID antenna  1255  may be a directional antenna that is pointed in the same direction as the laser. That is, positioned so that the greatest power radiated from the antenna  1255  is in the same direction as the beam from the laser  1200  to provide better isolation between the signal transmitted by the RFID antenna  1200  and the RFID tag  1260  in situations where other RFID readers are active in the same region as the PDT  100 . Thus, signals generated by other RFID tags being activated by other RFID readers will be to some extend isolated from the PDT  100 . 
         [0024]      FIGS. 4A ,  4 B,  4 C, and  4 D are RFID tags  20 ,  30 ,  40 , and  50 , respectively, which may be used with the present invention. In  FIG. 4A  the RFID tag  20  includes a RFID chip  22  coupled through a series photosensitive device  24  to an antenna  26 . A transparent window  1262  in the RFID tag  20  package allows light from the laser  1200  to strike the photosensitive device  24 . The photosensitive device  24  may be any of several types of photosensitive devices such as a phototransistor, etc. In one embodiment of the invention the photosensitive device  24  is not activated by ambient light such as sunlight, and interior lighting, but is sensitive to light at the frequency produced by the laser  1200  such that the activation of the RFID tag  20  does not occur unless a light within a predetermined frequency range strikes the photosensitive device  24 . The photosensitive device  24  is nonconductive in the absence of light that is within the predetermined frequency range thereby isolating the antenna  26  from the RFID chip  22 , and is conductive when light from the laser  1200  strikes the device  24  thereby coupling the antenna to the RFID chip  22 . The transparent window  1262  may contain a filter  28  which passes the light from the laser  1200 , but attenuates light of other frequencies to thereby lessen the possibility of the RFID tag  20  becoming activated at the wrong time. 
         [0025]    In the embodiment shown in  FIG. 4B  a photosensitive device  32  is connected to circuit nodes inside a RFID chip  34  and the antenna  26  is connected to the RFID chip  34 . The direct connection of the photosensitive device  32  and the RFID chip  34  provides alternative modes of the interaction of the photosensitive device  32  and the RFID chip  34 . In one mode the photosensitive device  32  operates in the same manner as the photosensitive device  24  and simply completes a connection between the two nodes inside the RFID chip  34  when made conductive by the laser  1200  which enables the RFID chip  34  to respond to the RFID reader unit  1250 , and inhibits the operation of the RFID chip  34  when the connection between the two nodes are blocked by the photosensitive device  32 . Alternatively, the RFID chip  34  may detect modulated light pulses from the laser  1200  from the duration of the alternating conductive and nonconductive states of the photosensitive device  32 , and enable the RFID chip  34  only when modulated light pulses of a certain type are received by the RFID tag  30 . In another variation, the light pulses from the laser  1200  may send data to the RFID chip  34  which causes the RFID chip to enter a mode of operation wherein the RFID chip  34  ignores the status of the photosensitive device  32  and operates as a conventional RFID tag, and also to return to the mode of operation requiring a laser signal to enable the RFID tag  30 . Thus, there would be a sequence of light pulses which would enable the RFID tag  30 , another sequence of light pulses which would cause the RFID chip  34  to switch to an operational mode in which the RFID tag  30  responds to a conventional reader without a laser light, and a third sequence of pulses which causes the RFID chip to return to the operational mode which requires laser pulses of a predetermined pattern to operate. This capability would allow the RFID tag  30  to respond to other RFID readers which don&#39;t have lasers such as may be used in a retail establishment in contrast with a warehouse or a distribution center. Since the photosensitive device  32  is not connected between the antenna  24  and the RFID chip  34 , the RF frequency tuning of the RFID tag  30  is not complicated by the RF characteristics of a photosensitive device between the antenna  24  and the RFID chip  34 . 
         [0026]    In the embodiment shown in  FIG. 4C  the RFID tag  44  has a second photosensitive device  44  connected in parallel with the photosensitive device  24  and has a transparent window  42  covered by a light blocking removable patch  46 . When the RFID tag  40  is used in an environment where it is desirable to require the laser  1200  for operation of the RFID tag  40 , the patch  46  is in place and blocks any light from striking the photosensitive device  42 . At another time, when the laser  1200  light is not needed to enable the RFID tag  40 , or when RFID readers without lasers are used to read the RFID tag  40 , the patch  46  is removed and the photosensitive device  42  completes the circuit between the antenna  26  and the RFID chip  22 . In one embodiment the photosensitive device  42  becomes conductive when it receives light anywhere within the visible spectrum such that the RFID tag  40  can be read by a conventional RFID reader anywhere that the RFID tag  40  is exposed to visible light. 
         [0027]    In  FIG. 4D  a RFID tag  50  has a RFID chip  52  which has photosensitive devices  24  and  42  connected in parallel to internal nodes within the RFID chip  52 . In this embodiment, since the photosensitive device  24  discriminates between visible light and light from the laser  1200 , the RFID chip  52  does not require pulse decoding circuitry. The photosensitive device  42 , the transparent window  44 , and the patch  42  operate in the manner described above. 
         [0028]    The RFID tag  60  in  FIG. 4E  has an RFID chip  62  with the battery  1264  connected to it. One terminal of the battery is coupled through the photosensitive device  24  to another connection to the RFID chip  62 . The RFID chip receives standby power from the battery  1264  when the photosensitive device  24  is non-conductive and receives full operating power when the photosensitive device  24  is conductive. Thus, when there is insufficient light entering the transparent window  1262  to make the photosensitive device  24  conductive, the RFID tag  60  ignores any RF received signals, and when light from the laser  1200  passes through the transparent window  1262 , the photosensitive device  24  becomes conductive at which time the RFID tag  60  will respond to RF signals from the RFID reader  1250 . The transparent window  1262  in  FIG. 4E  may also contain the filter  28 . 
         [0029]      FIG. 5  shows stacks  110  of containers, each of which has both a bar code  1204  and a RFID tag  1262  which can be laser enabled. The containers at the top of the stacks  110  are too high to be reliably read with a bar code reader, and if the RFID tags on the containers were conventional RFID tags, the data in the RFID tags could not be reliably read with a conventional RFID reader because of the presence of the other RFID tags. The present invention allows the RFID tags  1262  to be reliably read since they can be individually enabled using the PDT  100  by directing the laser light from the laser  1200  onto each of the RFID tags  1262  while activating the RFID reading assembly  1250 . 
         [0030]    While the invention has been described with reference to particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. 
         [0031]    Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.