Patent Publication Number: US-2009234981-A1

Title: Receiving apparatus, transmission/reception system and device control method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2008-067767, filed on Mar. 17, 2008; the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a receiving apparatus, a transmission/reception system and a device control method receiving a radio signal for controlling a device. 
     2. Description of the Related Art 
     When controlling a plurality of devices with signals from one remote controller (hereinafter, refer to as “remocon”), there is a possibility of generating errors in control due to an arrangement of devices or the like. For instance, if devices A and B are arranged on a straight line seen from the remote controller, the device B may receive a signal for controlling the device A, resulting that it may falsely operate. Note that there is disclosed a technique in which a position of remocon is detected and a device to be an object to be controlled is specified based on the position and a position of the device, to thereby control the device using signals including an ID of the device (refer to JP-A 2004-166193 (KOKAI)). 
     BRIEF SUMMARY OF THE INVENTION 
     In the above-described technique, it is required to set positional information on devices and to detect the position of the remocon. For this reason, it becomes necessary to reset the positional information on devices each time the devices are moved or a room is redecorated. 
     An object of the present invention is to provide a receiving apparatus, a transmission/reception system and a device control method having an improved reliability of controlling devices. 
     A receiving apparatus according to one aspect of the present invention includes: a receiving unit receiving a set of a plurality of signals in which at least a part of transfer rates is different; a rate detecting unit detecting a plurality of transfer rates of the plurality of signals; a first obtaining unit obtaining first information based on the plurality of transfer rates; a second obtaining unit obtaining second information based on the plurality of signals; and a control signal generating unit generating a control signal controlling a device based on the first and second information. 
     A transmission/reception system according to one aspect of the present invention includes the aforementioned receiving apparatus and a transmitting apparatus transmitting the above-described set of signals. 
     A device control method according to one aspect of the present invention includes: receiving a set of a plurality of signals in which at least a part of transfer rates is different; detecting a plurality of transfer rates of the plurality of signals; obtaining first information based on the plurality of transfer rates; obtaining second information based on the plurality of signals; and generating a control signal controlling a device based on the first and second information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are schematic diagrams in which a conventional information transfer method and an information transfer method according to an embodiment of the present invention are compared with each other. 
         FIG. 2  is a block diagram representing a control system  100  according to a first embodiment of the present invention. 
         FIG. 3  is a circuit diagram showing one structural example of a rectifying unit  132  shown in  FIG. 2 . 
         FIG. 4  is a timing chart representing a demodulated signal output from the rectifying unit  132 . 
         FIGS. 5(   a ) and  5 ( b ) are timing charts representing signals at a rate detecting unit  133 . 
         FIG. 6  is a graph representing a power spectrum of the demodulated signal or a received signal. 
         FIG. 7  is a flowchart representing one example of operating procedures of the control system  100 . 
         FIG. 8  is a flowchart representing one example of operating procedures of the control system  100 . 
         FIG. 9  is a block diagram representing a control system  200  according to a second embodiment of the present invention. 
         FIG. 10  is a flowchart representing one example of operating procedures of the control system  200 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Concepts of embodiments herein below will be explained. In the embodiments hereinbelow, a device is controlled by transferring a set of a plurality of signals in which at least a part of transfer rates is different. Specifically, control information is transferred by varying the transfer rate (baud rate). For instance, the control information is handled as information which transfers values of transfer rates or a difference in the values. As a result of this, it becomes possible to control the device using two main and sub transfer channels. The information through the main transfer channel is represented by a signal itself (for instance, an amplitude of signal (H/L)). The information through the sub transfer channel is represented by a transfer rate (or a difference in transfer rates). Through each of the main channel and the sub channel, a command controlling the device and an ID (Identification) of the device, for instance, can be transferred in parallel. As such, by transferring the control information using the two transfer channels, reliability and confidentiality when controlling the device can be improved. 
       FIGS. 1A and 1B  are schematic diagrams in which a conventional information transfer method and an information transfer method according to an embodiment of the present invention are compared with each other.  FIGS. 1(A) and 1(B)  respectively represent a signal transferred in a conventional embodiment and a signal transferred in the present embodiment. Note that a horizontal axis indicates time. In the conventional embodiment, a transfer rate is constant, and a device is controlled by a signal of a transfer rate R 0 . On the other hand, in the present embodiment, transfer rates are switched, and the device is controlled by a set of signals of transfer rates R 1 , R 2  and R 3 . Here, the set of signals indicates a plurality of signals which are transferred continuously or with a predetermined time interval therebetween during a predetermined period of time. Specifically, in an example of  FIG. 1(B) , a signal of transfer rate R 1 , a signal of transfer rate R 2  and a signal of transfer rate R 3  are collectively referred to as the set of signals of the transfer rates R 1 , R 2  and R 3 . The signals of the transfer rates R 1 , R 2  and R 3  can be transferred in a continuous manner as shown in  FIG. 1(B)  or can be transferred by leaving a predetermined time interval therebetween. 
     Hereinafter, embodiments of the present invention will be explained in detail. 
     First Embodiment 
       FIG. 2  is a block diagram representing a control system  100  according to a first embodiment of the present invention. The control system  100  includes a transmitting apparatus  110  transmitting/receiving signals of electromagnetic waves such as radio waves or light, and a receiving apparatus  130 . 
     The transmitting apparatus  110  is, for example, a portable transmission terminal, and functions as a so-called remocon which controls a device. The transmitting apparatus  110  includes a signal generating unit  111 , a modulation unit  112 , a control unit  113  and an antenna  114 , and transmits a set of a plurality of signals in which at least a part of transfer rates is different, as shown in  FIG. 1(B) . The signal generating unit  11  generates a predetermined basic signal (RF signal, for instance). The modulation unit  112  modulates the basic signal output from the signal generating unit  111 . The control unit  113  controls the modulation unit  112 , to thereby modulate the signal and switch the transfer rates. 
     The receiving apparatus  130  receives the signal to generate a command and a trigger signal, and outputs them to the device. The command is a signal for controlling the device. The trigger signal is a signal for shifting a state of the device (shift from a dormant state to an active state (power supply ON), for instance). The receiving apparatus  130  includes an antenna  131 , a rectifying unit  132 , a rate detecting unit  133 , a decoding unit  134 , an ID calculating unit  135 , an ID verifying unit  136 , a mode detecting unit  137 , an ID setting unit  138  and an output unit  139 . 
     The antenna  131  receives the signal transmitted from the transmitting apparatus  110 . 
     The rectifying unit  132  includes a power generating part in which power is generated by the signal received by the antenna  131 , and a demodulation part obtaining a demodulated signal from the signal. By the electric power supplied from the rectifying unit  132 , the rate detecting unit  133 , the decoding unit  134 , the ID calculating unit  135 , the ID verifying unit  136 , the mode detecting unit  137  and the ID setting unit  138  are driven. For this reason, the receiving apparatus  130  can be operated in low power consumption. 
       FIG. 3  shows one structural example of the rectifying unit  132  shown in  FIG. 2 . The rectifying unit  132  includes nMOS type transistors MR 1  and MR 2  connected in series. Gates and sources of the transistors MR 1  and MR 2  are short-circuit-connected, respectively (specifically, the transistors MR 1  and MR 2  are connected by a type of diode connection). A capacitor C 1  is connected to a wiring which connects the transistors MR 1  and MR 2 , and the RF signal is input from the antenna  131 . Further, a smoothing capacitor C 2  connected between a drain of the transistor MR 1  and the source of the transistor MR 2  generates an output voltage (rectified voltage). 
     When the RF signal is input, a half-wave current is flown through a path of the transistor MR 1 , the capacitor C 2  and the transistor MR 2 . As a result of this, direct current output voltages (rectified voltages) are generated at both ends of the capacitor C 2 . A lower terminal DC− of the rectifying unit  132  shown in  FIG. 3  is connected to a ground. An upper terminal DC+ of the rectifying unit  132  shown in  FIG. 3  is connected, as an output terminal of the rectifying unit  132 , to the rate detecting unit  133  and the decoding unit  134 . 
     The rate detecting unit  133  detects a transfer rate (concretely, a baud rate) of the demodulated signal output from the rectifying unit  132 . Next, a detection method of the transfer rate will be described. Hereinafter, two detection methods will be described, and either of the detection methods can be applied. Further, there is no problem if other methods are applied to the detection of the transfer rate. 
     (1) A first rate detection method will be explained. The demodulated signal output from the rectifying unit  132  is represented in  FIG. 4 . A time interval T from a rising edge to a falling edge of the demodulated signal is measured to thereby estimate the transfer rate. For example, the time interval T is measured at a plurality of times, and the transfer rate is calculated on the assumption that the measured minimum time interval T corresponds to the transfer rate. 
     Here, when a signal format is set so that the demodulated signal includes a fixed pattern (specific bit string) (when there is a preamble for estimating the baud rate), it is possible to estimate the transfer rate (baud rate) by one time of the measurement. 
     Hereinafter, details regarding the above will be described. Here, the rate detecting unit  133  is supposed to have an oscillating part (not shown) which generates clock signals. Further, an oscillation frequency of this oscillating part (not shown) is supposed to be larger than the baud rate to be detected. This is because the time interval T is measured by the clock signals. 
       FIGS. 5(   a ) and  5 ( b ) are timing charts representing signals at the rate detecting unit  133 .  FIG. 5(   a ) shows an example of the demodulated signals.  FIG. 5(   b ) shows an example of the clock signals output from the oscillating part of the rate detecting unit  133 . Here, first three bits B 1  through B 3  of the specific bit string are set as 1, 0 and 1, as shown in  FIG. 5(   a ). The rate detecting unit  133  counts the clock signals in the oscillating part from a rising edge to a falling edge of the first bit B 1 , and holds its result. Here, a count number n 1  is 5, as shown in  FIG. 5(   b ). 
     When the rate detecting unit  133  detects the next bit B 2 , the counting of clock signals in the oscillating part is started again, and the counting is continued until a rising edge of the next bit B 3  is detected. Here, a count number n 2  is 5. 
     The rate detecting unit  133  compares the count number n 1  with the count number n 2 , and it determines, when the n 1  is not less than (n 2 −a) nor more than (n 2 +a), the transfer rate is detected (a: error). Here, n 1 =5 and n 2 =5, so that the rate detecting unit  133  determines that the transfer rate is detected, and calculates a transfer rate R using, for instance, the following formulas. 
         R= 1/( n 0 *T ) 
         n 0=( n 1 +n 2)/2 
     n 0 : count number of clock signals per one symbol (one bit, in this example)
 
τ: time per one clock
 
     The rate detecting unit  133  detects the transfer rate each time it receives the signal. As a result of this, the transfer rates R 1 , R 2  and R 3  are detected in this order, for example. 
     (2) A second rate detection method will be described. Here, the transfer rate is estimated from a power spectrum of the demodulated signal output from the rectifying unit  132  or of the received signal output from the antenna  131 . 
       FIG. 6  is a graph representing the power spectrum of these signals. The power spectrum shown in  FIG. 6  includes a main lobe S 0  and side lobes S− and S+. When a frequency is changed so that it is increased or reduced with a maximum level of the main lobe S 0  as a center, there are frequencies f+ and f− corresponding to a minimum level of the main lobe S 0 . An inverse number (1/Δf 0 ) of an interval Δf 0  between the two frequencies f+ and f− is an estimated value of the transfer rate R. 
     The baud rate can be estimated without searching the minimum level of the main lobe S 0 . It is possible to estimate the baud rate from a frequency width Δf 1  at a point where the frequency is lowered by a predetermined value (X[dB]) from the maximum level of the main lobe S 0  of the power spectrum. A shape of the power spectrum is determined by a signal to be transmitted. Specifically, there is a relation of Δf 0 =α*Δf 1  between the frequency width Δf 1  and the frequency interval Δf 0 . If a coefficient α is determined, the baud rate can be estimated by calculating the frequency interval Δf 0  from the frequency width Δf 1 . The coefficient α can be stored in the rate detecting unit  133  as a lookup table or the like. 
     The decoding unit  134  performs a decoding processing on the demodulated signal based on rate information obtained in the rate detecting unit  133 , to thereby obtain a decoded signal (decoded information and data portion). Concretely, data regarding High/Low (1/0) of the demodulated signal is collected at a timing corresponding to the transfer rate R detected by the rate detecting unit  133 . The decoded signal can be used as a control command and control data of a rear stage device. The decoding unit  134  functions as a second obtaining unit obtaining second information based on the plurality of signals. 
     Hereinafter, a concrete example of an operation of the decoding unit  134  will be shown based on  FIGS. 5(   a ) and  5 ( b ). The decoding unit  134  collects data from the demodulated signal at a timing of each counter number of n 0  (here, each five count). With respect to the bit B 3 , by setting its rising edge as a reference, the demodulated signal is collected at a timing of counter number of n 0 /2 (after three counts). Thereafter, the decoding unit  134  continues to collect data at a timing of counter number of n 1  (here, each five count). The data collection is continued until the number of data bits reaches a predetermined number or a code indicating the end of data is received. 
     Note that the operational contents of the decoding unit  134  may be appropriately changed depending on a form of the signal to be transferred. 
     The ID calculating unit  135  obtains ID information from the transfer rate R detected in the rate detecting unit  133  (obtainment of rate portion). The ID calculating unit  135  functions as a first obtaining unit obtaining first information based on the plurality of transfer rates. Here, a concrete obtaining method of the ID information when the transfer rates R 1 , R 2  and R 3  are obtained will be explained. Note that in the following calculations, only integral parts are used and fractions below decimal point are rounded down. 
     (1) In the first method, a difference in the transfer rates is regarded as information. For example, when a reference rate and a rate resolution are respectively set as R 1  and ΔR, an amount of information to be transferred is represented by log 2 |R 2 −R 1 |/ΔR[bit] and log 2 |R 3 −R 1 |/ΔR[bit]. At this time, numeric values A 1 =|R 2 −R 1 |/ΔR and Δ 2 =|R 3 −R 1 |/ΔR themselves can be regarded as transfer information. Further, it is also possible to convert these numeric values A 1  and A 2  into the transfer information by referring to the lookup table. 
     These numeric values A 1  and A 2  can be respectively handled as ID information. In this case, the numeric values A 1  and A 2  may be the same value and may indicate the same ID information. Further, the numeric values A 1  and A 2  may be different values and may indicate different pieces of ID information. Furthermore, the numeric values A 1  and A 2  can be combined together and handled as one ID information. Here, a case is assumed where the ID information is obtained as information in which the numeric values A 1  and A 2  are combined together. For example, the numeric values A 1  and A 2  are disposed in this order on a high-order bit side and a low-order bit side. Alternatively, an opposite pattern thereof can also be conceivable. The ID information is obtained as described above. 
     (2) In the second method, the transfer rates themselves are regarded as information. An amount of information to be transferred is represented by log 2 (R 1 /ΔR) [bit], log 2 (R 2 /ΔR) [bit], and log 2 (R 3 /ΔR)[bit]. At this time, numeric values B 1 =R 1 /ΔR, B 2 =R 2 /ΔR, and B 3 =R 3 /ΔR themselves can be regarded as transfer information. Alternatively, it is also possible to convert these numeric values B 1  through B 3  into the transfer information by referring to the lookup table. The numeric values B 1  through B 3  can be handled independently or by combining them together. 
     The ID verifying unit  136  compares the ID information obtained in the ID calculating unit  135  with an original ID previously stored in the ID setting unit  138  and outputs its result to the output unit  139 . If these IDs coincide with each other, a command corresponding to the decoded signal is output from the output unit  139  to the rear stage device. If the IDs do not coincide with each other, the output of the command from the output unit  139  to the device is not conducted. 
     The mode detecting unit  137  compares the ID information calculated in the ID calculating unit  135  with the decoded information decoded in the decoding unit  134 . When the ID information and the decoded information coincide with each other, the ID information and information indicating coincidence are output to the ID setting unit  138 . Here, the coincidence between the ID information and the decoded information is supposed to indicate a shift into an ID changing mode in which an ID can be changed. In the ID changing mode, IDs held in the ID setting unit  138  can be changed. 
     The ID setting unit  138  holds one or a plurality of ID(s). When the ID setting unit  138  holds the plurality of IDs, it holds information indicating which ID among the plurality of IDs is the original ID. In preparation for changing the ID of device, the ID setting unit  138  holds the plurality of IDs. Among them, an ID used for controlling the device is the original ID. In the ID changing mode, the ID setting unit  138  changes the original ID. Specifically, the ID setting unit  138  functions as a changing unit changing an identification of device. 
     When the ID verifying unit  136  determines that the IDs coincide with each other, the output unit  139  outputs the command corresponding to the decoded signal. For example, the ID verifying unit  136  outputs a trigger signal for turning on the power supply to the device. As a result of this, a state of device changes from a dormant state to an active state, and electric power is supplied to the entire of the device. The output unit  139  functions as a control signal generating unit generating a control signal controlling the device based on the first and second information. 
     (Operation of Control System  100 ) 
     Hereinafter, an operation of the control system  100  will be described.  FIG. 7  and  FIG. 8  are flowcharts representing an example of operating procedures of the control system  100 .  FIG. 7  and  FIG. 8  respectively illustrate a control of device and a change of ID. 
     A. Control of Device 
     The control signal for controlling device is transmitted from the transmitting apparatus  110  and is received by the receiving apparatus  130  (step S 11 ). A rate portion (ID information) and a data portion (decoded information) of the control signal respectively represent the original ID and a control command (control data) of the device. 
     Here, when the control signal is represented by a set of signals of the transfer rates R 1 , R 2  and R 3 , for instance, the same command can be corresponded to each data portion of the signals of the transfer rates R 1 , R 2  and R 3 . In this case, it is possible to reduce a malfunction of device due to an error in transfer, by using a majority decision. 
     Note that when both the rate portion and the data portion of the signal represent the original ID, the signal corresponds to a later-described mode changing signal. 
     The control signal is demodulated in the rectifying unit  132 , to thereby generate the demodulated signal. A data portion (demodulated information) is obtained from the demodulated signal by the decoding unit  134  (step S 12 ). Meanwhile, a rate portion (ID information) is obtained from the demodulated signal by the rate detecting unit  133  and the ID calculating unit  135  (step S 13 ). Note that these steps S 12  and S 13  are simultaneously executed in parallel. 
     It is determined whether or not the rate portion (ID calculated by the ID calculating unit  135  (ID transmitted by radio wave)) coincides with the ID held in the ID setting unit  138  (step S 14 ). If these IDs coincide with each other, a command is output to the device. For example, the device in a dormant state is activated (power supply ON) (step S 15 ). If these IDs do not coincide with each other, the control command (control data) is discarded as invalid, and the device is not controlled. 
     As described above, when the same command is corresponded to each data portion of the signals of the transfer rates R 1 , R 2  and R 3 , for instance, the majority decision can be applied. Specifically, when the commands represented by these data portions do not completely coincide with each other, the command at the majority side is output to the device. As a result of this, the malfunction of device due to an error in transfer can be reduced. 
     B. Change of ID 
     A case is assumed where the ID of device is changed. By changing the ID of device held in the receiving apparatus  130 , it is possible to enhance a security and to eliminate a chance of overlap of IDs. Here, the ID of device is changed using the mode changing signal and an ID notifying signal. 
     (1) Change of Mode 
     The mode changing signal for setting the receiving apparatus  130  to the ID changing mode is transmitted from the transmitting apparatus  110  and is received by the receiving apparatus  130  (step S 21 ). Here, in the mode changing signal, both a rate portion (ID information) and a data portion (decoded information) are supposed to represent the original ID. The data portion (decoded information) and the rate portion (ID information) are obtained by the decoding unit  134  and the ID calculating unit  135 , respectively (steps S 22  and S 23 ). 
     It is determined whether or not the both rate portion (ID information) and the data portion (decoded information) coincide with the ID held in the ID setting unit  138  (step S 24 ). Specifically, if the three IDs coincide with one another, the receiving apparatus  130  is set to the ID changing mode (step S 25 ). 
     The above point will be more specifically described. The mode detecting unit  137  checks whether or not the rate portion (ID information) coincides with the data portion (decoded information), and outputs its result (first result information) to the ID setting unit  138 . Meanwhile, the ID verifying unit  136  compares the rate portion (ID information) obtained in the ID calculating unit  135  with the original ID previously stored in the ID setting unit  138 , and outputs its result (second result information) to the ID setting unit  138 . If both the first and second result information indicate coincidence, information indicating the ID changing mode is held in the ID setting unit  138 . 
     In the above description, both the rate portion (ID information) and the data portion (decoded information) of the mode changing signal coincide with the original ID. Instead of this, it is also possible to set a signal in which a command representing a mode change is indicated in a data portion (decoded information) as the mode changing signal. In this case, only the rate portion (ID information) coincides with the original ID. Since a processing at this time is not fundamentally different from one in a case where both the rate portion (ID information) and the data portion (decoded information) coincide with the original ID, a detailed explanation thereof will be omitted. 
     (2) Notification of ID 
     The ID notifying signal for notifying the receiving apparatus  130  of the changed ID is transmitted from the transmitting apparatus  110  and is received by the receiving apparatus  130  (step S 31 ). Here, in the ID notifying signal, both a rate portion (ID information) and a data portion (decoded information) are supposed to represent the changed ID. The data portion (decoded information) and the rate portion (ID information) are obtained by the decoding unit  134  and the ID calculating unit  135 , respectively (steps S 32  and S 33 ). 
     It is determined whether or not both the rate portion (ID information) and the data portion (decoded information) coincide with the ID held in the ID setting unit  138  (step S 34 ). As a result of this, if the three IDs coincide with one another, and the receiving apparatus  130  is in the ID changing mode (step S 35 ), the original ID held in the ID setting unit  138  is changed (step S 36 ). 
     In the above description, both the rate portion (ID information) and the data portion (decoded information) of the ID notifying signal coincide with the changed ID. Instead of this, it is also possible to set a signal in which a command representing an ID notification is indicated in a data portion (decoded information) as the ID notifying signal. In this case, only the rate portion (ID information) coincides with the original ID. Since a processing at this time is not fundamentally different from one in a case where both the rate portion (ID information) and the data portion (decoded information) coincide with the changed ID, a detailed explanation thereof will be omitted. 
     According to the present embodiment, it is possible to obtain two independent transfer channels by transferring a set of a plurality of signals in which at least a part of transfer rates is different. By using these two transfer channels, reliability and confidentiality when controlling a device can be improved. 
     (1) Improvement of Reliability 
     The ID of device can be changed by a signal from a side of remocon (side of transmitting apparatus  110 ). As a result of this, the malfunction of device can be reduced. Specifically, it is possible to reduce the malfunction of device due to an overlap of IDs or the like. Note that by using two transfer channels, the ID of device can be changed with a short code length. 
     By making the transfer rates of signal variable, it becomes easy to identify each signal, which enables to reduce the malfunction of device. Further, when the same information is corresponded to each data portion of a plurality of signals, it is possible to improve an error rate with the use of majority decision. It should be noted that different pieces of information can be corresponded to each data portion of the plurality of signals. 
     (2) Improvement of Confidentiality 
     The ID of device can be changed by a signal from a side of remocon (side of transmitting apparatus  110 ). As a result of this, it becomes easy to secure confidentiality of the ID of device against a threat from the outside. 
     Second Embodiment 
     A second embodiment of the present invention will be described.  FIG. 9  is a block diagram representing a control system  200  according to the second embodiment of the present invention. A receiving apparatus  230  includes the antenna  131 , the rectifying unit  132 , the rate detecting unit  133 , the decoding unit  134 , the ID calculating unit  135 , an ID verifying unit  236 , the mode detecting unit  137 , the ID setting unit  138 , a judgment unit  239  and a timer unit  240 . Note that the components substantially the same as those in the control system  100  are given the same reference numerals and detailed explanations thereof will be omitted. 
     The ID verifying unit  236  compares ID information obtained in the ID calculating unit  135  with an original ID previously stored in the ID setting unit  138 . If these IDs coincide with each other, the ID verifying unit  236  generates a timer activation signal and outputs it to the timer unit  240 . 
     Upon receiving the timer activation signal from the ID verifying unit  236 , the timer unit  240  starts counting time, and when the time is beyond the predetermined time, it outputs a warning signal. The timer unit  240  functions as a measuring unit measuring a time interval during which second and third signals are received. 
     The judgment unit  239  judges a presence/absence of the warning signal from the timer unit  240 , and when no warning signal exists, it outputs a command to a following stage device. 
     (Operation of Control System  200 ) 
       FIG. 10  is a flowchart representing one example of operating procedures of the control system  200 . Here, a case is assumed where a device is controlled by a control signal after an ID is changed. In the present embodiment, it is possible to prevent that a third person steals ID information of device to thereby control the device, at the time of update procedure and the like of ID information. 
     (1) Change of ID 
     The ID of device is changed (step S 41 ). For example, it is possible to change the ID of device by following a procedure shown in  FIG. 8 . Further, in accordance with the change of the ID of device, the counting of time by the timer unit  240  is started (step S 42 ). 
     (2) Control of Device 
     The device is controlled by the control signal. Basically, the device is controlled by a procedure similar to that shown in  FIG. 9  (steps S 11  through S 15 ). Here, when the control signal is received within a predetermined time after updating the ID, a control command is received and executed (step S 43 ). Meanwhile, when the control signal is not received within the predetermined time, the execution of control command is rejected (step S 43 ). According to the present embodiment, it is possible to prevent the device from being controlled by the third person even if the ID of device is stolen. 
     Other Embodiments 
     Embodiments of the present invention are not limited to the aforementioned embodiments and can be expanded and modified, and the expanded and modified embodiments are also included in the technical scope of the present invention. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.