JP5532483B2 - Proximity feeding / communication equipment - Google Patents

Description

  The present invention relates to a proximity power feeding / communication device, and in particular, proximity power feeding / communication capable of performing proximity power feeding from a base station side to a portable device side and improving a communication speed and a communicable area between the base station and the portable device. Relates to the device.

  A device that uses electromagnetic induction energy based on a radiated magnetic field of an electromagnetic wave transmitted from a base station as operating energy of a portable device, that is, a device that obtains operating energy of a portable device from the base station side by proximity power feeding is known.

  Conventionally, keyless entry devices for automobiles, RFID tag devices, IC card devices, and the like have been put to practical use as such devices. In these devices, the frequency used for proximity power feeding and communication is generally the same, and the base station and the portable device communicate using the same frequency as the electromagnetic wave used for proximity power feeding.

  For example, in the case of a keyless entry device for an automobile, the base station on the automobile side and the portable device on the key side each include an LF (Low Frequency) transmitter and an LF receiver, and communicate with proximity power feeding using an LF signal. . In this case, the timing at which proximity power feeding from the base station to the portable device is different from the timing at which the response signal is transmitted from the portable device to the base station. This is because transmission and reception cannot be performed simultaneously at the same frequency.

  In the method using LF signals of the same frequency, first, a LF signal for proximity power feeding is transmitted from the LF transmitter of the base station. The portable device receives the LF signal for proximity feeding transmitted from the base station, generates power based on the radiated magnetic field of the electromagnetic wave, operates the LF receiver and LF transmitter with the power, and outputs the LF response signal. Send. After the transmission of the proximity power feeding LF signal is completed, the base station receives the LF response signal transmitted from the LF transmitter of the portable device by the LF receiver.

  The same applies to the RFID tag device.The base station on the IC tag reader side and the portable device on the IC tag side each have an RF (Radio Frequency) transmitter and an RF receiver, and communicate with proximity power feeding using RF signals. I do. Even in this case, since transmission and reception cannot be performed simultaneously at the same frequency, the timing at which proximity power feeding from the base station to the portable device is different from the timing at which the response signal is transmitted from the portable device to the base station.

  In a method using RF signals of the same frequency, first, a proximity feed RF signal is transmitted from an RF transmitter of a base station. The portable device receives the proximity feed RF signal transmitted from the base station, generates power based on the radiated magnetic field of the electromagnetic wave, and operates the RF receiver and RF transmitter with the power to generate an RF response signal. Send. The base station receives the RF response signal transmitted from the RF transmitter of the portable device by the RF receiver after completing the transmission of the RF signal for proximity power feeding. The same applies to an IC card device that communicates with proximity power feeding using an RF signal.

  Non-Patent Document 1 describes an entrance / exit management system that activates a portable device using an LF signal and transmits a response signal from the portable device to a base station using a UHF signal. This entrance / exit management system includes a tag reader, an external antenna, and an active tag. Here, the tag reader includes an LF transmission / reception antenna, an LF transmission / reception circuit, a UHF antenna, a UHF reception circuit, a control circuit (CPU), an external antenna includes an LF antenna and an LF transmission circuit, an active tag includes an LF transmission / reception antenna, LF transceiver circuit, UHF antenna, UHF transmitter circuit, control circuit (CPU) and battery. If the battery is not depleted, the active tag is activated by the Wake pattern of the LF signal from the tag reader, and transmits the UHF response signal including the ID number to the tag reader through the UHF transmission circuit. However, when the battery is depleted, the active tag operates with the electric power induced by the LF signal from the tag reader, and sends the binary FSK (Frequency Shift Keying) modulated LF signal to the tag reader. The tag reader receives this LF signal by the LF receiving circuit.

Naoshima Hideo et al., "Hands-free entry / exit management system using active tags" Panasonic Electric Works Technical Report (Vol.57 No.2), pp. 52-57

However, the conventional method using the LF signal having the same frequency has the following problems.
(1) The area where proximity power can be supplied from the base station to the mobile device is the distance that can generate sufficient electromagnetic induction energy based on the radiated magnetic field of the electromagnetic wave of the proximity power supply LF signal transmitted from the base station in the mobile device. Limited to range. This distance range is about a few centimeters in consideration of radio law restrictions in the case of the weak method, and the installation area of the LF receiver of the base station that receives the LF response signal transmitted from the portable device is also the same Is limited to within the distance range. That is, the communication distance between the base station and the portable device is limited to about a few centimeters.
(2) Since the base station and the portable device communicate using the LF signal, the data transmission speed is limited to about several hundred bps. This data transmission rate is not suitable for data transmission using advanced encryption, and it is difficult to ensure sufficient security. Further, the data transmission time becomes long, and the base station cannot acquire the response signal transmitted from the portable device at an early stage.

In addition, the method using the RF signal having the same frequency has the following problems as in the method using the LF signal having the same frequency.
(1) The area where proximity power can be supplied from the base station to the mobile device is the distance in the mobile device where sufficient electromagnetic induction energy can be generated based on the radiated magnetic field of the electromagnetic wave of the proximity power supply RF signal transmitted by the base station. Limited to range. This distance range is about several tens of centimeters in the case of the weak method, considering the restrictions of the Radio Law. Is limited to within the distance range. That is, the communication distance between the base station and the portable device is limited to about several tens of centimeters.
(2) Since the base station and the portable device communicate using RF signals, the data transmission speed is limited to about several hundred bps. This data transmission rate is not suitable for data transmission using advanced encryption, and it is difficult to ensure sufficient security. Further, at such a data transmission rate, the data transmission time becomes long, and the base station cannot obtain a response signal transmitted from the portable device at an early stage.

  In addition, in the entrance / exit management system described in Non-Patent Document 1, when the battery of the active tag is not depleted, a weak LF signal is transmitted from the tag reader, and the UHF response of the specific low power method is transmitted from the active tag. Transmits a signal, but at the time of proximity power supply when the battery of the active tag is depleted, it performs proximity power supply using the LF signal from the base station to the mobile device, and also uses the LF signal to The response signal is transmitted to the station. In other words, when the battery of the active tag is depleted, the active tag operates with the power generated by electromagnetic induction based on the radiated magnetic field of the electromagnetic wave of the LF signal from the tag reader, and sends the response signal of the LF signal to the tag reader. To do. Therefore, even in this entrance / exit management system, the proximity power feeding method has a communication problem using the same frequency LF signal as that of a conventional keyless entry device for automobiles.

  An object of the present invention is to provide a proximity power feeding / communication device capable of performing proximity power feeding from a base station to a portable device and improving a communication speed and a communicable area between the base station and the portable device.

To solve the above problems, the present invention performs proximity power the portable device from the base station side, in the near feeding and communication apparatus for communicating between a mobile device and a base station, the base station, the time division and LF transmitting means for transmitting a LF signal comprising a contiguous feeding burst signals and communication signals, a UHF receiving means for receiving a UHF response signal transmitted from the portable device, control the LF transmission unit and the UHF transmission unit Base station side control means, and the portable device receives LF reception means for receiving an LF signal transmitted from the base station, UHF transmission means for transmitting a UHF response signal to the base station, and An LF proximity power receiving circuit that generates electric power based on a radiated magnetic field of an electromagnetic wave of an LF signal to be transmitted; For example, the LF reception unit, the UHF transmitter unit and the portable device control unit operates by the power generated by the LF proximity power receiving unit, the base station side control unit and the portable device control unit, The LF signal transmission period, the LF signal reception period, the UHF signal transmission period, and the UHF signal reception period are defined, and the LF signal reception period corresponds to the spatial propagation delay of the LF signal relative to the LF signal transmission period. The timing is controlled so as to be delayed by the time τ1, and the UHF signal receiving period is controlled by the third time τ3 corresponding to the spatial propagation delay of the UHF signal with respect to the UHF signal transmission period. Further, the portable device side control means determines that the start time of the UHF signal transmission period is based on the LF signal on the portable device side relative to the end time of the LF signal reception period. The timing is controlled so as to be delayed by a second time τ2 that can avoid being influenced by the base station, and the start time of the UHF signal reception period at the base station is higher than the end time of the LF signal transmission period. The basic feature is that the time is delayed by the total time of the third time (τ1 + τ2 + τ3) .

In the conventional method using the LF signal of the same frequency, it is necessary to arrange the LF receiving antenna of the base station within a range in which the LF signal for proximity feeding transmitted from the portable device can be received. The LF receiving antenna of the base station must be placed in the vicinity of the proximity feeding LF receiving antenna.
On the other hand, the present invention is characterized in that the portable device always responds to the base station with UHF data whether or not proximity power feeding is performed. Therefore, as an LF communication means from the portable device to the base station. The LF transmitter circuit on the portable device side and the LF receiver circuit on the base station side are not required.
Further, in the present invention, the base station includes LF transmission means and UHF reception means, the portable device includes LF reception means and UHF transmission means, and uses the LF signal for proximity power feeding from the base station to the portable device. Uses UHF signals with good power efficiency and radio wave propagation characteristics instead of LF signals and RF signals for transmission of response signals from the base station to the base station. In addition, UHF reception of LF radio waves is used for communication between the base station and mobile devices. Proximity feeding and communication are performed by a timing control method that does not affect the effect of the sneak noise caused by spatial propagation to the circuit, etc., so that the communicable area between the portable device and the base station can be improved. Thereby, the arrangement | positioning area of the receiving antenna of the base station for receiving the response signal from a portable device can be expanded.

  Specifically, the LF antenna for proximity feeding of the weak method and the receiving UHF antenna by the UHF response signal of specific low power can be arranged apart by about 5 m for the weak wireless method and about several tens of meters for the specific low power method. it can. For example, the proximity power supply antenna of the base station can be placed on the wall that the user can reach, and the reception antenna for the response signal from the portable device can be placed on the ceiling, floor, adjacent room, outdoors, etc. It is possible to increase the degree of freedom of the device configuration and arrangement in embodying the above.

  In addition, since the response signal is transmitted from the portable device as a specific low-power UHF signal, the communication speed can be increased, and as a result, the time required for data transmission can be shortened and encryption can be easily applied. It is possible to increase the confidentiality of communication and the response speed of the portable device.

  Furthermore, if the LF signal from the base station to the portable device is used for both proximity power supply and communication, the base station only needs to have an LF transmission antenna and an LF transmission circuit that are used for both proximity power supply and communication. Since there is no need to switch the antenna, the transmission circuit, and the reception circuit between the station and the portable device, the circuit configuration and the control thereof can be simplified.

It is a block diagram which shows embodiment of the base station which comprises the proximity electric power feeding and communication apparatus which concerns on this invention. It is a block diagram which shows embodiment of the portable device which comprises the proximity electric power feeding and communication apparatus which concerns on this invention. It is a block diagram which shows other embodiment of the base station which comprises the proximity electric power feeding and communication apparatus which concerns on this invention. It is a block diagram which shows other embodiment of the portable device which comprises the proximity electric power feeding and communication apparatus which concerns on this invention. It is a time chart which shows the transmission and reception timing of the LF signal between the base station and the portable device in the conventional system using the LF signal of the same frequency. It is a time chart which shows the timing of transmission and reception of the LF signal between the base station and the portable device in the conventional method using LF signals of different frequencies. It is a time chart which shows an example of the timing of transmission and reception between the base station of this invention, and a portable device. It is a flowchart which shows the basic operation | movement in this invention.

  The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a base station constituting a proximity power feeding / communication device according to the present invention.

  The base station shown in FIG. 1 includes an LF transmission antenna 1, an LF transmission circuit 2, a UHF reception antenna 3, a UHF reception circuit 4, and a base station side control circuit 5.

  The LF transmission antenna 1 and the LF transmission circuit 2 function as LF transmission means for proximity power feeding that transmits a LF signal and performs proximity power feeding to the portable device by the radiated magnetic field of the electromagnetic wave. The LF signal can include, for example, a communication LF signal such as a portable device activation signal or an authentication signal. In this case, the LF transmission antenna 1 and the LF transmission circuit 2 send a communication LF signal to the portable device. It also functions as a communication LF transmission means for transmission.

  The UHF receiving antenna 3 and the UHF receiving circuit 4 function as UHF receiving means for receiving a UHF response signal transmitted from the portable device. The UHF receiver circuit 4 also has a function of decrypting the UHF response signal if the UHF response signal transmitted from the portable device is encrypted. The UHF response signal received by the UHF receiving antenna 3 and the UHF receiving circuit 4 is sent to the control circuit 5.

  The base station side control circuit 5 controls necessary control according to the UHF response signal received by the UHF reception antenna 3 and the UHF reception circuit 4, for example, in the case of an entrance / exit management device, controls the lock opening / closing of the room entrance door. For this purpose, the base station side control circuit 5 includes an interface for exchanging data with an external device.

  Further, the base station side control circuit 5 controls the timing at which the LF transmission circuit 2 and the UHF reception circuit 4 operate. Although this timing control will be described in detail later, the timing at which the base station transmits the LF signal and the timing at which the UHF response signal is received do not overlap. At this time, the spatial propagation delay of the LF signal is also taken into consideration.

  FIG. 2 is a block diagram showing an embodiment of a portable device constituting the proximity power feeding / communication device according to the present invention.

  2 includes a LF receiving antenna 6 for proximity feeding, a LF receiving antenna 7 for communication, an LF receiving circuit 8 for communication, an LF proximity receiving circuit 9, a UHF transmitting antenna 10, a UHF transmitting circuit 11, and a portable device side. A control circuit 12 is provided.

  In general, it is known that a low impedance antenna has good power efficiency for electromagnetic induction by a radiated magnetic field, and a high impedance antenna has good reception efficiency for receiving data signals. In view of this, the portable device of this embodiment includes a low-impedance proximity feeding LF reception antenna 6 and a high-impedance communication LF reception antenna 7 separately. In order to improve the directivity, the communication LF receiving antenna 7 is a two-dimensional antenna having a two-axis configuration of X-axis and Y-axis or a three-dimensional antenna having a three-axis configuration of X-axis, Y-axis, and Z-axis. Is preferred.

  In the following, the operation when combined with the base station of FIG. 1 will be described, but it can also be combined with base stations of other embodiments described later.

  The LF receiving antenna 6 for proximity feeding receives the radiated magnetic field of the electromagnetic wave of the LF signal transmitted from the LF transmitting antenna 1 of the base station, and the LF proximity receiving circuit 9 is received by the LF receiving antenna 6 for proximity feeding. Electric power is generated by electromagnetic induction caused by the radiated magnetic field. The LF proximity power receiving circuit 9 includes a rectifier circuit that rectifies the power from the proximity feeding LF antenna 6 and a capacitor that stores the power. The electric power generated by the LF proximity power receiving circuit 9 is used as operating energy for each part of the portable device.

  The communication LF reception antenna 7 receives a communication LF signal transmitted from the LF transmission antenna 1 of the base station, a portable device activation signal, and an authentication signal. The communication LF reception circuit 8 sends the communication LF signal received by the communication LF reception antenna 7 to the control circuit 10. If the communication LF signal transmitted from the base station is encrypted, the LF reception circuit 8 also has a function of decrypting the signal.

  The UHF transmission antenna 10 transmits a UHF response signal, and the UHF transmission circuit 11 generates a UHF response signal.

  The portable device side control circuit 12 controls the timing at which the communication LF reception circuit 8, the LF proximity power reception circuit 9 and the UHF transmission circuit 11 operate, and if necessary, communication from the communication LF reception circuit 8 Processing such as starting the portable device and displaying the display unit is performed according to the LF signal. In the timing control, as with the base station, the timing for transmitting the UHF response signal and the timing for receiving the LF signal are not overlapped. At this time, the spatial propagation delay of the UHF response signal is also taken into consideration. Specifically, the timing control by the portable device side control circuit 12 is performed corresponding to the timing control by the base station side control circuit 5. This timing control can be realized by controlling using a counter, for example, based on the timing at which the signal transmitted from the base station is received by the portable device.

  FIG. 3 is a block diagram showing another embodiment of the base station constituting the proximity power feeding / communication device according to the present invention. In addition, the same code | symbol is attached | subjected to the same or equivalent part as FIG.

  The base station shown in FIG. 1 includes a pair of LF transmission antennas 1 and LF transmission circuits 2 and is configured to be used for both communication and proximity power feeding. The base station shown in FIG. 13, the communication LF transmission circuit 14, the proximity power supply LF transmission antenna 15 and the proximity power supply LF transmission circuit 16, and the communication transmission means and the proximity power transmission means are separated. According to this configuration, since a low impedance antenna can be used as the LF transmitting antenna 15 for proximity feeding, the efficiency of proximity feeding between the base station and the portable device can be increased, and the frequency of the communication LF signal can be increased. The frequency of the LF signal for proximity power feeding can be made different. The configuration and operation of other parts are the same as those in the embodiment of FIG.

  FIG. 4 is a block diagram showing another embodiment of the portable device constituting the proximity power feeding / communication device according to the present invention. In addition, the same code | symbol is attached | subjected to the same or equivalent part as FIG.

  The portable device shown in FIG. 2 has a configuration in which a proximity feeding LF reception antenna and a communication LF reception antenna are separately provided. However, the portable device shown in FIG. 4 has a proximity feeding LF reception antenna and a communication LF reception antenna. It is the structure which serves as one receiving antenna. If a two-dimensional or three-dimensional antenna is used as the LF receiving antenna 17, the proximity power feeding efficiency can be improved by improving the communication reception efficiency due to the directivity of the plurality of antennas and using the power sum received by the plurality of LF antennas. Both improvements can be satisfied together. The configuration and operation of the other parts are the same as in the embodiment of FIG.

  Next, transmission / reception timings in the base station and the portable device will be described with reference to FIGS. In order to clarify the difference in operation from the present invention, first, the operation in the prior art will be described.

  FIG. 5 is a time chart showing the transmission and reception timing of the LF signal between the base station and the portable device in the conventional method using the LF signal of the same frequency.

  As shown in the figure, the base station repeats LF transmission timing, LF response reception timing, and pause. For this purpose, the base station has an LF transmission / reception antenna and an LF transmission / reception circuit.

  At the LF transmission timing, the LF transmission circuit is switched to transmit the LF signal. The LF transmission timing is a period during which the radiated magnetic field due to the electromagnetic wave of the LF signal is turned on. Communication can be performed by including a communication signal (data) in the LF signal. At the LF response reception timing, the LF transmission circuit is switched to the LF reception circuit and transmission of the LF signal is stopped. The LF response reception timing is a period in which the radiation magnetic field is turned off. During this period, an LF response signal from the LF transmission circuit of the portable device supplied with power at the LF transmission timing is waited. The pause is provided so as not to continuously occupy one frequency (according to the Radio Law).

  The portable device repeats LF reception timing, LF response transmission timing, and pause. For this purpose, the portable device also has an LF transmission / reception antenna and an LF transmission / reception circuit.

  The LF reception timing corresponds to the LF transmission timing of the base station. At the LF reception timing, the LF reception circuit is switched to receive the LF signal from the base station and generate power by proximity power feeding. If a communication signal is included in the IF signal, response processing is performed. The LF response transmission timing corresponds to the LF response reception timing of the base station. At the LF response transmission timing, the LF receiving circuit is switched to the LF transmitting circuit and an LF response signal is transmitted. The pause is provided so as not to continuously occupy one frequency (according to the Radio Law). Such transmission / reception timing is also realized in an IC card that uses radio waves of RF signals.

  FIG. 6 is a time chart showing the transmission and reception timing of the LF signal between the base station and the portable device in the conventional method using LF signals of different frequencies. This is characterized in that the base station can always receive a response signal from the portable device.

  As shown in the figure, the base station repeats LF transmission timing and pause for transmitting the LF signal of frequency F1, and simultaneously repeats LF response reception timing and pause for receiving the LF response signal of frequency F2 different from F1. . Further, the portable device repeats the LF reception timing and pause for receiving the LF signal of frequency F1, and simultaneously repeats the LF response transmission timing and pause for transmitting the LF response signal of frequency F2. Therefore, the base station has LF transmission means for transmitting the LF signal of frequency F1 and LF reception means for receiving the LF signal of frequency F2, and the portable device has LF reception means and frequency for receiving the LF signal of frequency F1. Has LF transmission means to transmit F2 LF signal. The pause is provided so as not to continuously occupy one frequency (according to the Radio Law).

  The base station transmits an LF signal having the frequency F1 at the LF transmission timing, and waits for an LF response signal having the frequency F2 from the portable device that is powered by the LF signal at the LF reception response timing (simultaneously with the LF transmission timing). At the LF transmission timing, the radiation magnetic field due to the electromagnetic wave of the LF signal is turned on, and at the pause timing, the radiation magnetic field is turned off. The base station can transmit electric power by proximity power feeding using the radiated magnetic field to the portable device during the period when the radiated magnetic field is on at the LF transmission timing. Communication can also be performed by including a communication signal in the LF signal. On the other hand, the portable device fed during the period in which the radiation magnetic field is on (LF transmission timing) transmits the LF response signal at the LF response timing that is the same as the LF transmission timing.

  For example, the ISO 11785 technical guideline for animal identification using RFID tags defines the following power feeding method as an example of using LF (134.2 kHz ± 1.8 kHz).

  The radiation field from the LF transmitter on the base station side is set to 50 msec on and 3 msec off, and this operation is repeated to supply power to the transponder side of the portable device by the radiation field from the base station. The portable device is charged during the on-period (50 msec) of the radiating magnetic field. During this period, the LF receiver on the base station side always waits for a response signal from the full-duplex transponder on the portable device side. The proximity power feeding from the base station to the portable device and the transmission / reception timing of communication presented in the technical guideline of ISO11785 are also realized in the IC card using the radio wave of the RF signal.

  However, at the transmission / reception timing of FIG. 5, the base station immediately becomes the LF response reception timing when the on-period of the radiating magnetic field elapses, and the portable device immediately becomes the LF response transmission timing when the LF reception timing ends. In addition, at the transmission / reception timing of FIG. 6, the base station waits for a response signal transmitted from the portable device at the timing when the radiated magnetic field is sent to the portable device side. For this reason, in base stations and mobile devices, noise is generated due to the LF signal and RF signal wrapping around to the receiving circuit, and power supply noise generated by the radiated magnetic field of the electromagnetic wave of the LF signal affects the transmission circuit, causing communication. LF signal affects the transmission circuit.

  In particular, as shown in FIG. 6, the LF signal of two different frequencies F1 and F2 in the same frequency band is used, the proximity power is supplied from the base station to the portable device, and the LF response signal is transmitted from the portable device at the same time. In a base station or portable device, noise components (antenna effect) due to mutual electromagnetic fields induced on the conductor pattern between the antenna loop of the LF transmitting antenna and the antenna loop of the LF receiving antenna cannot be excluded. This causes problems such as reception by the LF reception antenna being disturbed by transmission by the LF transmission antenna, fading effects, and unstable communication, and a communication distance cannot be secured.

  As described above, in the case of using signals of different frequencies, it is common to simultaneously perform transmission and reception at each frequency, but in the present invention, in order to solve the above problem, the LF band and the UHF band When the proximity power supply from the base station to the portable device and the transmission of the response signal from the portable device to the base station are performed using frequency bands with greatly different frequencies, the electromagnetic field noise effect due to the harmonics is selected as much as possible. In addition, the timing at which the base station transmits the LF signal and the timing at which the UHF response signal is received do not overlap, and the timing at which the portable device transmits the UHF response signal and the timing at which the LF signal is received overlap. Do not become. At this time, the spatial propagation delay of the LF signal and UHF response signal is also taken into consideration.

  This allows the base station to receive the UHF response signal sent from the LF transmitter circuit through the LF transmitter antenna via the UHF receiver antenna. When receiving by the circuit, the noise caused by the radiated magnetic field wrapping around to the UHF receiving circuit, the antenna caused by the mutual electromagnetic field induced on the conductor pattern between the antenna loop of the LF transmitting antenna and the antenna loop of the UHF receiving antenna Noise due to the effect can be suppressed. In portable devices, when the LF signal transmitted from the base station is received by the LF receiving circuit via the LF receiving antenna, the noise caused by the UHF response signal transmitted from the UHF transmitting antenna wraps around to the LF receiving circuit side. In addition, it is possible to suppress the noise caused by the antenna effect due to the mutual electromagnetic field induced on the conductor pattern between the antenna loop of the UHF transmitting antenna and the antenna loop of the LF receiving antenna, and the radiation received by the LF receiving antenna It is possible to suppress the influence on the UHF transmission circuit due to the power supply noise generated inside the portable device due to the magnetic field, and the influence on the UHF transmission circuit due to the LF signal.

  Therefore, in the base station, it is possible to prevent the reception of the UHF response signal by the UHF receiving antenna due to the radiated magnetic field of the electromagnetic wave of the LF signal transmitted from the LF transmitting antenna. Thereby, it is possible to prevent the reception of the response signal transmitted from the portable device from becoming unstable. In portable devices, the reception of LF signals by the LF reception antenna can be prevented by the UHF response signal transmitted from the UHF transmission antenna of the portable device, and transmission from the LF transmission antenna of the base station can be prevented. It is possible to prevent the transmission of the UHF response signal from becoming unstable due to the LF signal. Therefore, it is possible to increase the communicable distance by suppressing the decrease in the effective communication distance between the base station and the portable device as much as possible, and to realize stable communication.

  The reception interference at the UHF receiving antenna due to the radiated magnetic field of the electromagnetic wave of the LF signal transmitted from the LF transmitting antenna of the base station is more effective by forming the LF transmitting antenna and the UHF receiving antenna separately from each other. Can be prevented. Specifically, the LF transmitting antenna and the UHF receiving antenna may be formed separately without being formed on the same conductor pattern.

  FIG. 7 is a time chart showing an example of transmission and reception timings between the base station and the portable device of the present invention.

  The base station repeats LF transmission timing and pause. Also, the UHF response reception timing is set in a preset period within the pause period. At the LF transmission timing, the proximity power supply burst signal (LF signal) and the communication signal (LF signal) are transmitted to the portable device, and at the UHF response reception timing, a UHF response signal from the portable device is awaited. The pause is provided so as not to continuously occupy one frequency (according to the Radio Law).

The LF transmission at the LF transmission timing can be performed by one LF transmission unit (FIG. 1) or by separately providing the communication transmission unit and the proximity power transmission unit (FIG. 3). The LF transmission timing period (TSL) is defined by the time until the operating energy is secured by proximity power feeding in the portable device. Proximity feed, not just near the feeding burst signal, Ru also performed by the LF transmission data.
For example, the LF transmission timing period (TSL) is obtained by preliminarily obtaining the time from when the portable device is completely in the initial state until the generation of operating energy necessary for starting each part of the portable device. Can do.

  The portable device repeats the LF reception timing and pause. Also, the UHF response transmission timing is set in a preset period within the pause period. The LF reception timing, pause, and UHF response transmission timing correspond to the LF transmission timing, pause, and UHF response reception timing at the base station, respectively.

  However, the LF reception timing and pause period are delayed by the delay correction amount τ1 with respect to the LF transmission timing and pause period on the base station side, and the UHF response reception timing is delayed by the delay correction amount τ3 with respect to the UHF response transmission timing. τ1 and τ3 are set to a time corresponding to the spatial propagation delay of the LF signal and the UHF response signal. Further, the start time of the UHF response transmission timing is delayed by the delay correction amount τ2 from the end time of the LF reception timing. The delay correction amount τ2 is set to, for example, a value corresponding to one bit of the LF signal (data) in order to reliably avoid the UHF response signal from being affected by the reception of the LF signal on the portable device side. Furthermore, when the base station side operates the LF transmission and the UHF reception continuously, the base station prevents the UHF response signal from the portable device from entering the LF transmission circuit side and disturbing the next LF transmission. The UHF transmission timing on the portable device side is set so that the UHF reception timing can be ended with an interval (for example, several msec to several tens msec) before the start time of the LF transmission timing on the side. As a result, in the base station, there is an interval between the LF transmission timing and the UHF response reception timing, so that the interference due to the LF signal wrapping around to the UHF reception circuit side does not occur.

  The portable device receives the proximity power supply burst signal transmitted from the base station at the LF transmission timing at the LF reception timing, and generates electric power by electromagnetic induction. Further, a response signal for LF transmission data is generated as necessary.

  For the LF reception in the portable device, either a proximity power receiving means and a communication LF receiving means (FIG. 2) or a common LF receiving antenna (FIG. 4) can be used. The LF reception timing period (TRL) for performing LF reception is defined by the time until the operating energy of the portable device is secured. Specifically, the LF reception timing period (TRL) is set to be the same as the LF transmission timing period (TSL).

  The portable device uses the power generated by the proximity power supply from the base station as operating energy, and transmits a UHF response signal within the UHF response transmission timing as necessary. The UHF response transmission timing (TSU) is defined by the operable time of the portable device. That is, the UHF response transmission timing (TSU) period is set in advance within a time that does not exceed the time during which the portable device can operate due to the operating energy generated by the proximity power supply from the base station.

  The base station waits for the UHF response signal transmitted from the portable device at the UHF response reception timing. The UHF response reception timing period (TRU) is defined based on the UHF response transmission timing period (TSU) defined by the operable time of the portable device. Specifically, the maximum value of the UHF response reception timing period (TRU) is the same as the maximum value of the UHF response transmission timing period (TSU) when considering retransmission of the UHF response signal from the mobile device side. The

  FIG. 7 shows a time chart in the case where the LF signal is transmitted twice from the base station. Actually, the LF signal is transmitted from the base station to the portable device, and the LF signal is received. The operation of transmitting a UHF response signal from a portable device that is powered by proximity and receiving the UHF response signal at the base station may be completed once, or may be repeated three or more times.

  As shown in the time chart shown in FIG. 7, when transmitting and receiving an LF signal and a UHF signal between the base station and the portable device, by providing delay correction amounts τ1, τ2, and τ3 in the transmission and reception timing, Noise caused by the electromagnetic field of the LF signal transmitted from the LF transmitting antenna circulates to the UHF receiver circuit, and each other induced on the conductor pattern between the antenna loop of the LF transmitting antenna and the antenna loop of the UHF receiving antenna. Noise due to the antenna effect due to the electromagnetic field can be suppressed. Also, in mobile devices, noise caused by the UHF response signal transmitted from the UHF transmission antenna wrapping around to the LF reception circuit, induced on the conductor pattern between the antenna loop of the LF reception antenna and the antenna loop of the UHF transmission antenna It is possible to suppress noise caused by the antenna effect due to the mutual electromagnetic field. As a result, the effective communication distance between the base station and the portable device can be maximized.

  In order to ensure security during communication, it is preferable that the base station and the portable device have the function. To ensure security, for example, one or both of a method for individually identifying a base station and a portable device and a method for encrypting a communication LF signal can be used.

  In the method for individually identifying a base station and a mobile device, individual IDs are assigned to the base station and the mobile device in advance, and communication within the group is enabled based on the ID. To identify a base station belonging to a group capable of communication and a plurality of portable devices, register a combination table of the base station ID and a plurality of portable device IDs in the base station memory and the portable device memory respectively. The base station and the mobile device are individually identified using those IDs.

  Specifically, an LF signal including the base station ID is transmitted from the base station at the time of proximity power feeding. If the base station ID included in the received LF signal is a base station ID in a communicable group including the mobile device, the mobile device starts normally and transmits a UHF response signal including the mobile device ID . If the base station ID is not applicable, the portable device does not respond and does not output unnecessary UHF radio waves. The base station receives the UHF response signal transmitted from the portable device, and recognizes that it is a correct UHF response signal if the included portable device ID is a portable device ID in a communicable group including its own base station.

  In the method of encrypting the communication LF signal, a general rolling code method using an M-sequence counter can be adopted. In the data arrangement of the LF signal to be transmitted and the arrangement / extraction of valid data, the base station and mobile device belonging to the group use unique correspondence and initial values, and the communication LF signal is different from the simple rolling code method. Encryption and decryption may be performed.

  FIG. 8 is a flowchart showing the basic operation in the present invention. Here, a method of individually identifying the base station and the portable device is employed to ensure security.

  First, it is determined whether or not a trigger is given in the base station (S11). The trigger is given at each timing when the LF transmission timing (TSL) starts if the power of the base station is on. If no trigger is given, wait until a trigger is given. If a trigger is given, LF transmission timing (TSL) is reached, and the base station transmits an LF signal including its own base station ID (S12). The transmission of the LF signal is continuously performed during the LF transmission timing period (TSL), and ends when the LF transmission timing period (TSL) elapses.

  The portable device generates power by electromagnetic induction due to the electromagnetic field radiated from the LF signal transmitted from the base station (S13). The portable device uses the generated power as operating energy and activates each unit (LF reception circuit, portable device side control circuit, UHF transmission circuit) (S14 to S16). If a special signal such as an activation code signal is required for this activation, that signal is also included in the LF signal.

  Next, the portable device performs validity authentication based on the IF signal transmitted from the base station (S17). If the validity is authenticated here, the portable device transmits a UHF response signal (S18). Specifically, as described above, the validity authentication is performed based on the base station IDs constituting the group, and the base station ID included in the received LF signal includes the base stations in the communicable group including the own mobile device. If it is a station ID, it starts normally and transmits a UHF response signal including the ID of the portable device. However, if the validity is not authenticated, the process returns to step S11.

  The portable device transmits a UHF response signal within the UHF response transmission timing period (TSU) (S18). This UHF response signal includes the portable device ID. The base station receives the UHF response signal within the period (TSU) of the UHF response reception timing (S19). Here, the authenticity of the portable device is also performed using the base station ID included in the UHF response signal. Thereafter, the steps from S11 are repeated as necessary.

  Although the embodiments have been described above, the present invention is not limited to the above embodiments, and includes various modifications. For example, a battery may be provided in the portable device, and the power generated by the LF proximity power receiving circuit may be used as an alternative power source for the battery when the battery is exhausted.

  Also, the proximity power feeding system (LF transmitting antenna or LF transmitting circuit) and the communication system (UHF receiving antenna or UHF receiving circuit) in the base station can be separated, and both can be arranged at separate positions. .

1 ... LF transmitting antenna, 2 ... LF transmitting circuit, 3 ... UHF receiving antenna, 4 ... UHF receiving circuit, 5 ... Base station side control circuit, 6 ... LF for proximity power feeding Reception antenna, 7 ... Communication LF reception antenna, 8 ... Communication LF reception circuit, 9 ... LF proximity power reception circuit, 10 ... UHF transmission antenna, 11 ... UHF transmission circuit, 12・ ・ ・ Mobile device side control circuit, 13 ... Communication LF transmission antenna, 14 ... Communication LF transmission circuit, 15 ... Proximity feeding LF transmission antenna, 16 ... Proximity feeding LF transmission circuit, 17 ... LF receiving antenna

Claims (10)

Proximity power supply from the base station side to the portable device side, and the proximity power supply and communication device that performs communication between the base station and the portable device
The base station includes an LF transmission unit that transmits an LF signal including a time-division proximity power supply burst signal and a communication signal, a UHF reception unit that receives a UHF response signal transmitted from the portable device, and the LF transmission. And base station side control means for controlling the UHF transmission means,
The portable device has LF reception means for receiving an LF signal transmitted from the base station, UHF transmission means for transmitting a UHF response signal to the base station, and an electromagnetic wave of the LF signal transmitted from the base station. An LF proximity power reception circuit that generates electric power based on a radiated magnetic field, and a portable device side control unit that controls the LF reception unit and the UHF transmission unit,
The LF receiving unit, the UHF transmitting unit, and the portable device side control unit operate with power generated by the LF proximity power receiving unit,
The base station side control means and the portable device side control means define an LF signal transmission period, an LF signal reception period, a UHF signal transmission period and a UHF signal reception period, and an LF signal reception period with respect to the LF signal transmission period. Is controlled so as to be delayed by a first time τ1 corresponding to the spatial propagation delay of the LF signal, and the UHF signal reception period corresponds to the spatial propagation delay of the UHF signal relative to the UHF signal transmission period. The timing is controlled so as to be delayed by a third time τ3, and the portable device side control means determines that the start time of the UHF signal transmission period is the UHF signal on the portable device side relative to the end time of the LF signal reception period. Is controlled so as to be delayed by a second time τ2 that can avoid being affected by the LF signal, and the start time of the UHF signal reception period at the base station is LF A proximity power feeding / communication device characterized by being delayed by a total time (τ1 + τ2 + τ3) of the first, second and third times from the end of the signal transmission period. It said base station side control unit defines the LF signal transmission period by the time to be reserved in the operation for energy of the portable device is the LF proximity power receiving unit, the LF transmission unit transmitting state between the LF signal transmission period to become defines a UHF signal reception period by feeding possible time of the LF proximity power receiving means, and controls so that the UHF reception unit is receiving state between the UHF signal reception period,
Wherein the portable device control unit defines the LF signal reception period by the time to be reserved in the operation for energy of the portable device is the LF proximity power receiving unit, the LF reception unit receiving state between the LF signal reception period to become the defining a UHF signal transmission period by feeding time of the LF proximity power receiver, according to claim 1, wherein the UHF transmission means between the UHF signal transmission life and controls so as to transmit state Proximity feeding / communication device as described in 1.   The proximity power feeding / communication according to claim 1, wherein the LF proximity power receiving means includes a capacitor that stores energy generated based on a radiation magnetic field of an LF electromagnetic wave transmitted from the base station. apparatus.   4. The proximity power feeding / communication device according to claim 1, wherein the LF transmission unit includes an LF transmission antenna and an LF transmission circuit that are used for both proximity power feeding and transmission of a communication LF signal. 5.   4. The proximity power feeding / communication device according to claim 1, wherein the LF transmission unit includes a separate LF transmission antenna and an LF transmission circuit for proximity power feeding and transmission of a communication LF signal. 5. .   6. The proximity power feeding / communication device according to claim 1, wherein the LF reception unit and the LF reception antenna of the LF proximity power reception unit are used in common.   6. The proximity power feeding / communication device according to claim 1, further comprising an LF receiving antenna of the LF receiving unit and an LF receiving antenna of the LF proximity power receiving unit separately.   The portable device has a function of authenticating the validity of the portable device, and transmits a UHF response signal through the UHF transmission means only when the validity is authenticated by the portable device. The proximity power feeding / communication device according to any one of 7.   The base station transmits the LF signal including the base station ID, and has a function of authenticating the validity of the portable device based on the base station ID included in the UHF response signal transmitted from the portable device. The portable device authenticates the validity of the portable device based on a base station ID included in the received LF signal, and transmits the portable device including the portable device ID in the UHF response signal. 8. Proximity feeding / communication device according to 8.   The said portable machine is further equipped with a battery, and uses the electric power generated by the LF proximity power receiving means as an alternative power source of the battery when the battery is exhausted. Proximity feeding / communication device.

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