Abstract:
The present invention relates to an RFID system in which an RFID tag has an adjustable detection range. An RFID system according to an embodiment of the present invention includes an RFID reader receiving a signal, reading the signal, and transmitting a command signal; and an RFID tag having unique information, sensing the magnitude of the command signal received from the RFID reader, generating a voltage according to the magnitude, adjusting a tag detection range according to the generated voltage, and transmitting a response signal corresponding to the command signal to the RFID reader.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to a radio frequency identification (RFID) system including an RFID tag the detection range of which can be varied. 
         [0002]    RFID systems are contactless identification systems used to wirelessly receive signals generated from RFID tags attached to various articles and process information about the articles. 
         [0003]    Such an RFID system includes an RFID tag having unique information, an RFID reader reading a signal from the RFID and transmitting a corresponding command to the RFID tag, and other operating software and a network. 
         [0004]    For the RFID reader to detect the RFID tag, first, the RFID tag should receive a signal transmitted from the RFID reader through an antenna of the RFID tag, and then the RFID reader should receive a response signal from the RFID tag without errors. 
         [0005]    A detection range between the RFID reader and the RFID tag in which the RFID reader can detect the RFID tag is affected by the magnitude of a signal received at the REID tag, the power consumption of the RFID tag, and the magnitude of a signal transmitted from the RFID reader. 
         [0006]    Recently, applications of RFID systems are being gradually expanded, and the detection range between an RFID reader and an RFID tag is required to be varied from short distances to long distances. However, detection ranges of existing tags are specified by design parameters during fabrication and thus are similar. Moreover, detection ranges of tags cannot be adjusted without changing antenna or hardware configurations. 
         [0007]    Accordingly, a response signal of an RFID tag is varied according to the magnitude of a signal received at an RFID tag, the power consumption of the RFID tag, and the magnitude of a signal transmitted from an RFID reader. As a result, in some cases, an RFID reader may not detect an RFID tag. 
       SUMMARY 
       [0008]    Embodiments provide an RFID system in which an RFID tag has an adjustable detection range. 
         [0009]    In one embodiment, an RFID system includes an RFID reader receiving a signal, reading the signal, and transmitting a command signal; and an RFID tag having unique information, sensing the magnitude of the command signal received from the RFID reader, generating a voltage according to the magnitude, adjusting a tag detection range according to the generated voltage, and transmitting a response signal corresponding to the command signal to the RFID reader. 
         [0010]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a block diagram illustrating a configuration of an RFID system in which a tag according to a first embodiment of the present invention has an adjustable detection range. 
           [0012]      FIG. 2  is a block diagram illustrating a configuration of an RFID system in which a tag according to a second embodiment of the present invention has an adjustable detection range. 
           [0013]      FIG. 3  is a block diagram illustrating a configuration of an RFID system in which a tag according to a third embodiment of the present invention has an adjustable detection range. 
           [0014]      FIG. 4  is a block diagram illustrating a configuration of an RFID system in which a tag according to a fourth embodiment of the present invention has an adjustable detection range. 
           [0015]      FIG. 5  is a view illustrating an internal circuit configuration of a received-signal control unit of an RFID system in which the tag according to the first embodiment of the present invention has an adjustable detection range. 
           [0016]      FIG. 6  is a view illustrating an internal circuit configuration of a power consumption control unit of an RFID system in which the tag according to the second embodiment of the present invention has an adjustable detection range. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0017]    Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. 
         [0018]      FIG. 1  is a block diagram illustrating a configuration of an RFID system in which a tag according to a first embodiment of the present invention has an adjustable detection range. 
         [0019]    Referring to  FIG. 1 , the RFID system in which a tag according to a first embodiment of the present invention has an adjustable detection range includes an RFID tag  110  and an RFID reader  120 . 
         [0020]    The RFID tag  110  includes unique information and generates a signal of a certain frequency. 
         [0021]    The RFID reader  120  receives a signal from the RFID tag  110  and reads the signal. 
         [0022]    The RFID tag  110  includes an antenna  111 , a received-signal control unit  112 , a power generation unit  113 , a reception unit  114 , a transmission unit  115 , a control unit  116 , and a wake-up signal generation unit  117 . 
         [0023]    The antenna  111  transmits/receives signals to/from the RFID reader  120 . 
         [0024]    The received-signal control unit  112  controls the magnitude of an RF signal received through the antenna  111 . 
         [0025]      FIG. 5  is a view illustrating an internal circuit configuration of a received-signal control unit of an RFID system in which the tag according to the first embodiment of the present invention has an adjustable detection range. 
         [0026]    Referring to  FIG. 5 , the received-signal control unit  112  may be configured with a combinational circuit in which a plurality of unit circuits connecting an on/off switch  501  with a resistor  502  in series are connected in parallel to each other as shown in (A) of  FIG. 5 . Also, the on/off switch  501  and a capacitor  503  may be connected as shown in (B) of  FIG. 5  and the on/off switch  501  and an inductor  504  may connected as shown in (C) of  FIG. 5  in the same manner as (A) of  FIG. 5 . 
         [0027]    The received-signal control unit  112  controls the on/off switch  501  in a circuit to change impedance. Accordingly, the received-signal control unit  112  reduces the magnitude of a received signal received from the RFID reader  120  to reduce a detection range to the RFID tag  110 . 
         [0028]    In contrast, received signal may be amplified by the change of impedance. Accordingly, the effect is the same as that of the distance between the RFID reader  120  and the RFID tag  110  being less. 
         [0029]    The power generation unit  113  receives an RF signal through the received-signal control unit  112  and generates a voltage. The generated voltage is converted to a DC by a rectifier (not shown) to be supplied to the RFID tag  110  of a system as a power source. 
         [0030]    The reception unit  114  demodulates an RF signal input from the antenna  111  and converts the RF signal to digital data. 
         [0031]    The transmission unit  115  transmits a response signal corresponding to a command signal received from the RFID reader  120 . The response signal may be modulated to be suitable for a wireless communication, and then transmitted. 
         [0032]    The control unit  116  controls and monitors operations and states of the elements. Also, the control unit  116  generates a command for controlling the magnitude of an RF signal received through the antenna  111  and outputs the command to the received-signal control unit  112 . Also, the control unit  116  generates a response signal corresponding to the command signal received from the RFID reader  120  and outputs the response signal to the transmission unit  115 . 
         [0033]    The control unit  116  interprets the command received from the RFID reader  120  through the reception unit  114 . The control unit  116  generates a command for the received-signal control unit  112  to control the magnitude of the RF signal received through the antenna  111 , by using the interpreted value. 
         [0034]    The wake-up signal generation unit  117  compares the voltage generated by the power generation unit  113  with a predetermined wake-up reference voltage. According to a result of the comparison, if the generated voltage is greater than the predetermined wake-up reference voltage, the wake-up signal generation unit  117  generates a wake-up signal and outputs the generated wake-up signal to the control unit  116 . 
         [0035]    A memory unit  118  may store data processed by the control unit  116  and unique information of the RFID tag  110 . Also, the memory  118  may store a wake-up reference voltage value and a reference value for controlling the magnitude of a received RF signal. 
         [0036]    An external signal input unit  119  may receive a control command from outside to control the received-signal control device. 
         [0037]    In the RFID system according to the first embodiment of the present invention, the RFID tag  110  controls the magnitude of the RF signal received from the RFID reader  120  as above and adjusts the magnitude of the received signal. Accordingly, the effect is the same as that of the distance between the RFID reader  120  and the RFID tag  110  being greater or less, and thus a detection range of the RFID reader  102  is decreased or increased. 
         [0038]      FIG. 2  is a block diagram illustrating a configuration of an RFID system in which a tag according to a second embodiment of the present invention has an adjustable detection range. 
         [0039]    Referring to  FIG. 2 , the RFID system according to the second embodiment of the present invention includes the RFID tag  210  and the RFID reader  220 , like the RFID system described in the first embodiment of  FIG. 1 . 
         [0040]    The RFID tag  210  has unique information and transmits a signal of a certain frequency to the RFID reader  220 . 
         [0041]    The RFID reader  220  receives by radio and reads the signal from the RFID tag  210 , and transmits an operation command signal to the RFID tag  210 . 
         [0042]    The RFID tag  210  includes an antenna  211 , a power generation unit  212 , a reception unit  213 , a transmission unit  214 , a control unit  215 , a power consumption control unit  216 , and a wake-up signal generation unit  117 . 
         [0043]    The antenna  211  transmits/receives signals to/from the RFID reader  220 . 
         [0044]    The power generation unit  212  generates a voltage corresponding to an RF signal received through the antenna  211 . The generated voltage is supplied to the RFID tag as a power source. 
         [0045]    The reception unit  213  demodulates the RF signal received through the antenna  211  and converts the RF signal to digital data. 
         [0046]    The transmission unit  214  transmits a response signal corresponding to the RF signal received from the RFID reader  220  to the RFID reader  220 . 
         [0047]    The control unit  215  controls and monitors operations and states of the elements. The control unit  213  receives digital data from the reception unit  213 , processes the digital data, and outputs the digital data to the transmission unit  214  which transmits the processed data to the RFID reader  22 . 
         [0048]    The control unit  215  interprets a signal received from the RFID reader  220  through the reception unit  213  according to the second embodiment of the present invention, and on the basis of the interpreted value, may generate a control command for the power consumption control unit  216  to control power. 
         [0049]    The power consumption control unit  216  controls power consumed by the control unit  215  and the power consumption control unit  216 . 
         [0050]    The power consumption control unit  216  will be described below in detail with reference to  FIG. 6 . 
         [0051]      FIG. 6  is a view illustrating an internal circuit configuration of a power consumption control unit of an RFID system in which the tag according to the second embodiment of the present invention has an adjustable detection range. 
         [0052]    Referring to  FIG. 6 , the power consumption control unit  216  may be configured with a combinational circuit in which a plurality of unit circuits connecting an on/off switch  601  with a resistor  602  in series are connected in parallel to each other as shown in (A) of  FIG. 6 . Also, the on/off switch  601  and a capacitor  603  may be connected as shown in (B) of  FIG. 5  and the on/off switch  601  and an inductor  604  may connected as shown in (C) of  FIG. 5  in the same manner as (A) of  FIG. 5 . 
         [0053]    The power consumption control unit  216  controls operations of the on/off switch  601  to increase or decrease power consumption of the RFID tag  210 . 
         [0054]    Accordingly, the detection range of the RFID reader  220  to the RFID tag  210  is increased or decreased. 
         [0055]    That is, if power consumption of the RFID tag  210  is increased, power for operating the RFID tag  210  is generated above average power consumption. Accordingly, the distance between the RFID reader  220  and the RFID tag  210  should be less, and thus a detection range of the RFID reader  102  to the RFID tag  210  is decreased. 
         [0056]    In contrast, if power consumption of the RFID tag  210  is decreased, power for operating the RFID tag  210  is generated below the average power consumption. Accordingly, the distance between the RFID reader  220  and the RFID tag  210  should be greater, and thus a detection range of the RFID reader  102  to the RFID tag  210  is increased. 
         [0057]    Accordingly, the detection range of the RFID reader  220  to the RFID tag  210  is adjustable by controlling power consumption of the RFID tag  210  as above. 
         [0058]    The wake-up signal generation unit  117  compares the voltage generated by the power generation unit  212  with a predetermined wake-up reference voltage. According to a result of the comparison, if the generated voltage is greater than the predetermined wake-up reference voltage, the wake-up signal generation unit  117  generates a wake-up signal and outputs the generated voltage to the control unit  215 . 
         [0059]    The memory  218  may store a reference value for controlling the amount of power consumption of the power consumption control unit  216  and the control unit  215 . The control unit  215  may generate a command for the power consumption control unit  216  to control power consumed by the control unit  215  and the power consumption control unit  216 . 
         [0060]    An external signal input unit  219  may receive a control command from outside. The power consumption control unit  216  may be controlled according to the input control command. 
         [0061]      FIG. 3  is a block diagram illustrating a configuration of an RFID system in which a tag according to a third embodiment of the present invention has an adjustable detection range. 
         [0062]    Referring to  FIG. 3 , the RFID system according to a third embodiment of the present invention includes a configuration for controlling power consumption as described in the second embodiment. However, the RFID system may not include the power consumption control unit  216  but a clock generation unit  316   a  and a clock frequency control unit  316   b  which will be described below. 
         [0063]    The RFID system according to the third embodiment of the present invention includes an RFID tag  310  and an RFID reader  320 . 
         [0064]    The RFID tag  310  has unique information and generates a signal of a certain frequency. 
         [0065]    The RFID reader  320  receives a signal from the RFID tag  310  wirelessly and reads the signal. Also, the RFID reader  320  transmits an operation command signal to the RFID tag  310 . 
         [0066]    The RFID tag  310  includes an antenna  311 , a power generation unit  312 , a reception unit  313 , a transmission unit  314 , a control unit  315 , a clock generation unit  316   a , a clock frequency control unit  316   b , and a wake-up signal generation unit  317 . 
         [0067]    The antenna  311  transmits/receives signals to/from the RFID reader  320 . 
         [0068]    The power generation unit  312  generates a voltage corresponding to an RF signal received through the antenna  311 . The generated voltage is supplied to the RFID tag as a power source. 
         [0069]    The reception unit  313  receives the RF signal from the RFID reader  320  through the antenna  311 . Also, the reception unit  313  demodulates the received RF signal and converts the signal to digital data. 
         [0070]    The transmission unit  314  transmits a response signal corresponding to the RF signal received from the RFID reader  320  to the RFID reader  320 . 
         [0071]    The control unit  315  controls and monitors operations and states of the elements. The control unit  315  receives and processes data received from the reception unit  313 , and generates a response signal corresponding to the data. The generated control signal is output to the transmission unit  314 . 
         [0072]    The control unit  315  interprets the instruction input from the RFID reader  320  through the reception unit  313 . The control unit  315  may generate a control signal for controlling a frequency of a clock generated in the clock generation unit  316   a  on the basis of the interpreted value. 
         [0073]    The clock generation unit  316   a  generates a clock required for the control unit  315  to process data and outputs the clock to the control unit  315 . 
         [0074]    The clock frequency control unit  316   b  controls a clock frequency generated by the clock generation  316   a  to control power consumption of the control unit  315  and the clock generation unit  316   a.    
         [0075]    The wake-up signal generation unit  317  compares the voltage generated by the power generation unit  312  with a predetermined wake-up reference voltage. According to a result of the comparison, if the generated voltage is greater than the reference voltage, the wake-up signal generation unit  317  generates a wake-up signal and outputs the generated voltage to the control unit  315 . 
         [0076]    A memory unit  318  may store data processed by the control unit  315  and unique information of the RFID tag  310 . The memory  318  may store a reference value for controlling the amount of power consumption of the control unit  315  and the clock generation unit  316   a . The control unit  315  generates a command on the basis of the reference value for the clock frequency control unit  316   b  to control the clock frequency generated by the clock generation unit  316   a.    
         [0077]    An external signal input unit  319  may receive a control signal from outside to control the clock frequency control unit  316   b.    
         [0078]    As above, the RFID system according to the third embodiment of the present invention may control a clock frequency related to clock generation and thus adjust power consumption of the RFID tag  310 . Accordingly, the detection range of the RFID reader  320  to the RFID tag  310  is adjustable. 
         [0079]    That is, if the clock frequency control unit  316   b  increases the clock frequency, the clock generation unit  316   a  generates a fast clock, thereby increasing power consumption of the control unit  315 . In this case, if power consumption of the RFID tag  310  is increased, power is generated more than average power consumption to operate the RFID tag  310 . Accordingly, the distance between the RFID reader  320  and the RFID tag  310  should be less, and thus a detection range of the RFID reader  102  to the RFID tag  310  may be decreased. 
         [0080]    In contrast, if power consumption of the RFID tag  310  is decreased, power less than the average power consumption is required to operate the RFID tag  310 . Accordingly, the distance between the RFID reader  320  and the RFID tag  310  should be greater, and thus a detection range of the RFID reader  320  to the RFID tag  310  may be extended. 
         [0081]    Accordingly, the detection range of the RFID reader  320  to the RFID tag  310  is adjustable by controlling the clock frequency as above and thus controlling power consumption of the RFID tag  310 . 
         [0082]      FIG. 4  is a block diagram illustrating a configuration of an RFID system in which a tag according to a fourth embodiment of the present invention has an adjustable detection range. 
         [0083]    Referring to  FIG. 4 , the RFID system according to the embodiment of the present invention includes an RFID tag  410  and an RFID reader  420 . 
         [0084]    The RFID tag  410  has unique information and generates a signal of a certain frequency. 
         [0085]    The RFID reader  420  reads an RF signal received from the RFID tag  410  and transmits an operation command signal to the RFID tag  410 . 
         [0086]    The RFID tag  410  includes an antenna  411 , a power generation unit  412 , a reception unit  413 , a transmission unit  414 , a control unit  415 , a wake-up signal generation control unit  416 , and a wake-up signal generation unit  417 . 
         [0087]    The antenna  411  transmits/receives signals to/from the RFID reader  420 . 
         [0088]    The power generation unit  412  generates a voltage corresponding to an RF signal received through the antenna  311 . The generated voltage is supplied to the RFID tag  410  as a power source. 
         [0089]    The reception unit  413  receives an RF signal from the RFID reader  420  through the antenna  411 . Also, the reception unit  313  demodulates the received RF signal and converts the signal to digital data. 
         [0090]    The transmission unit  414  transmits a response signal corresponding to the RF signal received from the RFID reader  420  to the RFID reader  420 . 
         [0091]    The control unit  415  controls operations and states of the elements. The control unit  415  receives and processes data received from the reception unit  413 , and generates a response signal corresponding to the data. 
         [0092]    The control unit  415  may interpret a command received from the RFID reader  420  through the reception unit  413 , and using the interpreted value, the wake-up signal generation control unit  416  may generate a wake-up control signal related to wake-up signal generation. 
         [0093]    The wake-up signal generation control unit  416  generates a control signal for generating a wake-up signal according to a command of the control unit  415 . 
         [0094]    The wake-up signal generation unit  417  receives a wake-up control signal generated from the wake-up signal generation unit  416  and generates a wake-up reference voltage. The wake-up signal generation unit  417  compares the voltage generated by the power generation unit  412  with the wake-up reference voltage. According to a result of the comparison, if the voltage generated by the power generation unit  412  is greater than the wake-up reference voltage, the wake-up signal generation unit  417  generates a wake-up signal and outputs the wake-up signal to the control unit  415 . 
         [0095]    A memory unit  418  stores data processed by the control unit  415  and unique information of the RFID tag  410 . Also, the memory  418  may store a predetermined wake-up reference voltage value for controlling a wake-up signal generation. 
         [0096]    An external signal input unit  419  may receive a control signal for controlling the wake-up signal generation control unit  416  from outside. 
         [0097]    In the RFID system according to the fourth embodiment of the present invention, the magnitude of a received signal of the RFID tag  410  is generally proportional to the distance between the RFID tag  410  and the RFID reader  420 . That is, the power generation unit  412  of the RFID tag  410  generates a voltage on the basis of the RF signal received through the antenna  411 . The wake-up signal generation unit  417  compares the generated voltage with the predetermined wake-up reference voltage. According to a result of the comparison, if the voltage generated by the power generation unit  412  is greater than the wake-up reference voltage, the wake-up signal generation unit  417  generates a wake-up signal and outputs the wake-up signal to the control unit  415 . 
         [0098]    Accordingly, the wake-up reference voltage is controlled through the wake-up signal generation control unit  416 , thereby adjusting the magnitude of the voltage generated by the power generation unit  412 . 
         [0099]    That is, if the wake-up reference voltage is controlled to be greater, the RFID tag  410  generates a voltage greater than the wake-up reference voltage which is increased to generate a wake-up signal. Accordingly, to generate greater voltage, the separation distance between the RFID tag  410  and the RF reader  420  should be short, and thus the detection range of the RFID reader  420  to the RFID tag  410  is shortened. 
         [0100]    In contrast, if the wake-up reference voltage is controlled to be less, the RFID tag  410  generates a voltage less than the wake-up reference voltage which is increased to generate a wake-up signal. Accordingly, the detection range of the RFID reader  420  to the RFID tag  410  is lengthened. 
         [0101]    The RFID system according to the first to fourth embodiments of the present invention can control the magnitude of a received signal by the received-signal control unit, control the amount of power consumption of the RFID tag by the power consumption control unit, control the amount of power consumption of the RFID tag by the clock frequency control unit, control the magnitude of the wake-up reference voltage generated in the wake-up signal generation unit, thereby controlling the detection range of the RFID reader to the RFID tag. 
         [0102]    Any reference in this specification to “one embodiment,” “an embodiment,” “exemplary embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to affect such feature, structure, or characteristic in connection with others of the embodiments. 
         [0103]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.