JP2007200080A - Data transmission method and sensor system using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently transmit detection data detected by a moving detection unit to a reading device. <P>SOLUTION: Power of a power supply supplied from a reading device 30 is transmitted to a detection unit 10 mounted on a detection target through a non-contact magnetic field coupling. A temperature, pressure, etc., of a detection target are detected by a sensor element 11 and a detection circuit 12. Voltage determination circuits 20-1, 20-2 determine the magnitude of the received power of the power supply, and if the determination result is not smaller than an operation assurance value, a control circuit 13 is set to an operation mode to transmit the detection data. If the determination result is smaller than the assurance value but not smaller than a value holdable in the detection data, the circuit 13 is set in a holding mode to hold the detection data, and if the determination result is recovered not smaller than the assurance value, the circuit 13 is returned to the operation mode to transmit the held detection data. If the determination result is smaller than the value holdable in the detection data, the circuit 13 is set in a stoppage mode to stop the operations. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a physical quantity (for example, temperature, pressure, stress, displacement, acceleration, electric quantity, etc.) of a moving detection object is detected by a sensor attached to the detection object, and the detected data is contactless. The present invention relates to a data transmission method for transmitting data to the reading device side and a sensor system using the same.

  Conventionally, as a sensor system that detects a physical quantity of a moving detection target with a sensor and transmits the detected data to the reading device side, for example, techniques described in Patent Documents 1, 2, and 3 below are known. ing. In the sensor systems described in Patent Documents 1 to 3, a detection unit having a sensor element and a transmitter is mounted on the tire side of the vehicle, and the detection unit detects the tire pressure and temperature and wirelessly transmits the detection data. The transmission data is received by a receiver on the side of the reading device attached to the vehicle body, and it is determined whether or not an abnormality has occurred in the tire, thereby improving the safety of the vehicle.

JP 2004-161113 A JP 2003-291615 A JP-A-10-104103

  However, the conventional data transmission method from the detection unit to the reader and the sensor system using the same have the following problems (A) and (B).

(A) Problems in data transmission Conventionally, a detection unit having a sensor element and a transmitter is mounted on the tire side of the vehicle, and the air pressure and temperature of the tire are detected, and this detection data is wirelessly received by a receiver on the vehicle body side. To send to. However, as described in paragraph 0028 of Patent Document 1, while the vehicle is running, the detection unit attached to the tire also rotates as the tire rotates. The reception sensitivity of the receiver changes, and there is a point that the receiver cannot receive within a certain rotation angle range (this point is also referred to as “null point”). In order to prevent this, it is sufficient to increase the power of the transmission radio wave. However, since such problems as radio wave regulation and interference occur, such measures cannot be taken. Therefore, in the technique of Patent Document 1, the detection data is wirelessly transmitted from the transmitter to the receiver in a tire rotation angle range (for example, a range of 180 ° ± 60 °) that avoids the null point.

  However, in such a configuration, since the detection data must be transmitted within a limited rotation angle range during one rotation of the tire, the rotation speed of the tire increases and the time of the rotation angle range decreases. Then, there is a possibility that the data transmission is interrupted before the detection unit rotates and completes the transmission of the detection data. In order to avoid this, if data transmission is completed in a short time, the data transmission rate must be increased. However, if the data transmission rate is increased, the bandwidth required for wireless communication is increased and the signal pair of the communication line is increased. There arises a problem that it is difficult to ensure the noise ratio (S / N ratio) at or above the allowable value.

(B) Problems in maintenance and inspection for battery consumption Conventionally, since a battery for supplying power is provided in the detection unit, maintenance and inspection for battery consumption is required, which is disadvantageous. In order to eliminate this, a transmission signal in which the power source power is superimposed on the reading device side is made, sent to the detection unit side without contact, the transmission signal is demodulated on the detection unit side, and the power source is taken out. It is conceivable to supply the internal circuit of the detection unit. However, similarly to the problem (A), the transmission signal is interrupted during one rotation of the tire, and it is difficult to supply sufficient power from the reader to the detection unit. As a result, the detection unit Therefore, there is a problem that the detection data cannot be transmitted to the reading device side to the end.

  The data transmission method of the present invention is attached to a moving detection object, receives power supply power supplied from the outside and receives a control signal, and based on the received power supply power and the received control signal, the detection target A detection unit that detects a change in a physical quantity in an object and transmits detection data to the outside; and the control signal that is installed away from the detection unit and that is non-contact with the detection unit and on which the power supply power is superimposed And a reading device that receives the detection data transmitted from the detection unit. A data transmission method in a sensor system.

  The detection unit determines the magnitude of the received power supply, and when the determination result is equal to or greater than the operation guarantee value, the detection unit is set to an operation mode and the detection data is transmitted for a certain period of time. When the determination result is smaller than the operation guarantee value but greater than or equal to the value that can hold the detection data, the detection unit is set to a holding mode to hold the detection data, and the determination result is the operation When recovering to a guaranteed value or more, the mode is shifted from the holding mode to the operation mode, the held detection data is transmitted after a certain waiting time, and the determination result is smaller than the holdable value of the detection data Then, the operation of the detection unit is stopped by setting the stop mode.

  The sensor system of the present invention is a sensor system including a detection unit and a reading device similar to those described above.

  The detection unit determines the magnitude of the received power supply and outputs a determination result; and when the determination result is equal to or higher than an operation guarantee value, sets the detection unit to an operation mode and First setting means for transmitting detection data and waiting for a certain time; and when the determination result is smaller than the operation guarantee value but greater than a value that can hold the detection data, the detection unit is set to a holding mode. The second setting means for holding the detection data, and when the determination result in the holding mode is restored to the operation guarantee value or more, the mode is shifted from the holding mode to the operation mode, and after a certain waiting time, A third setting means for transmitting the held detection data; and the detection result when the determination result is smaller than a holdable value of the detection data. And a fourth setting means for stopping the operation of the detection unit by setting the knit stop mode.

  According to the data transmission method and the sensor system of the present invention, even when the power reception time on the detection unit side is short and a series of operation sequences cannot be completed at once, the operation can be continued after the power reception state is recovered. After the transmission is interrupted, the detection data held in the holding mode is resumed from where it is sent, so that the time required to continuously supply the necessary power before the detection data is sent can be shortened. Furthermore, for example, even when the coupling magnetic field is interrupted for a short time, there is a time during which no signal is sent for the waiting time, so it can be determined that the signal transmission has been interrupted on the reader side, and a series of data transmission and reception are received by mistake. There is no.

  The sensor system is mounted on a moving detection target, receives power supply power given from the outside and receives a control signal, and based on the received power supply power and the received control signal, a physical quantity of the detection target A detection unit that detects a change and transmits detection data to the outside; and a control unit that is installed away from the detection unit and that is superposed on the power supply power by non-contact magnetic coupling to the detection unit. A reader that transmits to the detection unit and receives the detection data transmitted from the detection unit.

  The detection unit determines a magnitude of the received power supply and outputs a determination result; and when the determination result is equal to or higher than an operation guarantee value, sets the detection unit to an operation mode and sets the detection data And a first setting means for waiting for a predetermined time by a timer circuit, and when the determination result is smaller than the operation guarantee value but greater than a value capable of holding the detection data, the detection unit is set to the holding mode. A second setting means for setting and holding the detection data in a holding register; and when the determination result in the holding mode recovers to the operation guaranteed value or more, the timer circuit is shifted from the holding mode to the operation mode, And a third setting means for transmitting the held detection data after a certain waiting time, and the determination result holds the detection data When less than capacity values, and a fourth setting means for stopping the operation of the detection unit sets the detection unit to stop mode.

(Configuration of Example 1)
(Configuration of FIGS. 1 and 2)
FIG. 1 is a schematic configuration diagram of a sensor system showing Embodiment 1 of the present invention. FIG. 2 is a perspective view showing a tire of a vehicle to which the sensor system of FIG. 1 is applied.

  The sensor system shown in FIG. 1 detects, for example, the pressure of the tire 1 of the vehicle shown in FIG. 2 and the temperature closely related to this pressure as a moving detection object. A detection unit 10 that is embedded, and a reading device 30 that is attached to the vehicle body side away from the detection unit 10 and that supplies power to the detection unit 10 and transmits and receives data by non-contact magnetic coupling. It has. Since the tire 1 in FIG. 2 rotates, in the area 2 where the distance between the detection unit 10 and the reading device 30 is short, the driving magnetic field supplied from the reading device 30 to the detection unit 10 reaches the detection unit 10 and operates. On the other hand, in the area 3 where the distance between the detection unit 10 and the reading device 30 is long, the intensity at which the drive magnetic field supplied from the reading device 30 to the detection unit 10 reaches the detection unit 10 becomes weak.

  The detection unit 10 includes a sensor element 11 having a temperature detection sensor element 11A that detects the temperature of the tire 1 and a pressure detection sensor element 11B that detects the pressure of the tire 1, and the sensor element 11 includes a temperature detection circuit. A detection circuit 12 having 12A and a pressure detection circuit 12B is connected.

  For example, the temperature detecting sensor element 11A constituting the sensor element 11 is configured by a thermistor resistance element or the like having a large temperature dependence, and the pressure detecting sensor element 10B is a variable capacitor or the like whose capacitance value changes by an external pressure. It is configured. The temperature detection circuit 12A constituting the detection circuit 12 has a function of converting the temperature detection value detected by the temperature detection sensor element 11A into temperature detection data consisting of a digital signal, and the pressure detection circuit 12B is A circuit having a function of converting a pressure detection value detected by the pressure detection sensor element 11B into pressure detection data including a digital signal.

  A control circuit 13 having a temperature control circuit 13A and a pressure control circuit 13B is connected to the detection circuit 12. The control circuit 13 is a circuit that controls the entire detection unit 10, and includes, for example, a central processing unit (hereinafter referred to as “CPU”), an individual circuit, or the like.

  The control circuit 13 is connected with a holding register 14, a first timer circuit 15-1, and a second timer circuit 15-2. The holding register 14 is a register for holding detection data when the control circuit 13 enters a holding mode due to insufficient driving power. The first timer circuit 15-1 is a circuit for causing the operation of the detection unit 10 to wait for a predetermined time T1 when the detection unit 10 completes one data transmission to the reading device 30. The second timer circuit 15-2 waits for the operation of the detection unit 10 for a predetermined time T2 before the control circuit 13 is supplied with sufficient driving power to return from the holding mode to the operation mode and start the operation again. It is a circuit to make it.

  Further, the detection unit 10 has an antenna coil 16 that transmits and receives power and signals in a contactless manner with respect to the reading device 30, and the antenna coil 16 is wound around the bar antenna 17. A capacitor (not shown) is connected to the antenna coil 16, and the antenna coil 16 and the capacitor are tuned to the frequency of the alternating magnetic field supplied from the reading device 30. The antenna coil 16 is further connected to a power source means (for example, a rectifier circuit) 18. A storage means (for example, a capacitor) 19 is connected to the rectifier circuit 18, and the rectifier circuit 18 is connected to the first and second rectifier circuits 18. It is connected to the control circuit 13 via the voltage determination circuits 20-1 and 20-2.

  The rectifier circuit 18 rectifies the AC electromotive voltage induced in the antenna coil 16 to generate a DC power supply voltage for driving the detection unit, and supplies this to the control circuit 13 or the like via the first and second voltage determination circuits. It is a circuit to give. The capacitor 19 is connected between the power supply line and a reference potential (ground potential), and accumulates the charge of the DC power supply voltage generated by the rectifier circuit 18. The capacitor 19 may be replaced with other storage means such as a rechargeable battery. The first voltage determination circuit 20-1 functions as first and third setting means, compares the DC power supply voltage generated by the rectifier circuit 18 with the operation guarantee value of the detection unit 10, and guarantees the operation. When the voltage becomes lower than the value, the control circuit 13 is reset. The second voltage determination circuit 20-2 functions as the second and fourth setting means, and determines whether or not the voltage that is lower than the operation guarantee value but can hold the detection data is received. This is a circuit that performs the determination and gives the determination result to the control circuit 13. The rectifier circuit 18, the capacitor 19, and the voltage determination circuits 20-1 and 20-2 constitute determination means.

  The antenna coil 16 is connected to the control circuit 13 via a clock detection circuit (CK detection circuit) 21 and is connected to the control circuit 13 via a first receiving means (for example, a reception circuit) 22. The circuit 13 is connected to the antenna coil 16 via first transmission means (for example, a transmission circuit) 23.

  The clock detection circuit 21 is a circuit that detects a clock signal superimposed on an AC electromotive voltage induced in the antenna coil 16 and applies the clock signal to the control circuit 13. The receiving circuit 22 receives a control signal from the reading device 30 superimposed on the AC electromotive voltage induced in the antenna coil 16, demodulates the control signal, and gives a command (command) and data to the control circuit 13. Circuit. The control circuit 13 has functions such as output of detected data by controlling execution of a given command and processing of data. The transmission circuit 23 is a circuit that generates a transmission signal by modulating the detection data supplied from the control circuit 13 and transmits the transmission signal to the reading device 30 via the magnetic field coupling of the antenna coil 16.

  The reading device 30 includes a loop antenna 31 that is magnetically coupled to the antenna coil 16, an oscillation circuit 32 that oscillates a carrier for power supply power (for example, a carrier of 125 KHz), and a modulation circuit 33 that is connected to the oscillation circuit 32. A second transmission means (for example, a transmission circuit) 34 connected between the modulation circuit 33 and the loop antenna 31 and a second reception means (for example, a reception circuit) 35 connected to the loop antenna 31 are provided. Have. Further, a control circuit 36 having data processing and control functions is connected to the modulation circuit 33 and the reception circuit 35, and the control circuit 36 is configured by a computer that controls the entire sensor system via an interface 37. It is connected to the host controller 38.

  The modulation circuit 33 is a circuit that modulates a command or data output from the control circuit 36 with a carrier for power supply power supplied from the oscillation circuit 32. The transmission circuit 34 is a circuit that converts the modulation signal modulated by the modulation circuit 33 into a transmission signal and transmits the transmission signal to the detection unit 10 via the loop antenna 31. The reception circuit 35 is a circuit that receives and demodulates detection data and the like sent from the detection unit 10 via the loop antenna 31 and outputs the demodulated detection data and the like to the control circuit 36. The control circuit 36 is a circuit that receives detection data from the reception circuit 35, performs a correction operation on the detection data and the like, and sends the processing result to the host controller 38 via the interface 37.

(Configuration of FIG. 3)
FIG. 3 is a circuit diagram showing a configuration example of the temperature detecting sensor element 11A, the temperature detecting circuit 12A, and the temperature control circuit 13A in FIG.

  The sensor element 11A is formed of, for example, a thermistor resistance element having a large temperature dependency in which the resistance value Rth varies with temperature, and a detection circuit 12A is connected to the sensor element 11A. The detection circuit 12A is, for example, a circuit that detects a temperature by using a resistance element in a time constant circuit including a capacitance element and a resistance element that determine an oscillation frequency of the CR oscillation circuit. The detection circuit 12A includes a control circuit. 13A is connected. The control circuit 13A includes a control unit that outputs various control signals and temperature detection data (for example, count numbers N1, N2) for controlling the detection circuit 12A, a calculation unit, a data storage unit, and the like. It is composed of a CPU and the like.

  The detection circuit 12A is connected to a reference element (for example, a reference resistance element) 41A having a fixed resistance value Rref serving as a reference, a first oscillation circuit 42-1A connected to the sensor element 11A, and the reference resistance element 41A. And a second oscillation circuit 42-2A having the same characteristics as the first oscillation circuit 42-1A. The first oscillation circuit 42-1A constitutes a CR oscillation circuit together with the sensor element 11A, operates according to the control signal of the control circuit 13A, oscillates at a frequency corresponding to the resistance value of the sensor element 11A, and outputs a clock signal. It is a circuit to do. The second oscillation circuit 42-2A constitutes a CR oscillation circuit together with the reference resistance element 41A, operates in accordance with the control signal of the control circuit 13A, oscillates at a frequency corresponding to the resistance value of the reference resistance element 41A, and generates a clock signal. Is a circuit that outputs.

  The detection circuit 12A includes a first memory 43-1A that operates according to a control signal from the control circuit 13A and sets a set number (for example, a set value) M1, which is a count (count) number, and a control of the control circuit 13A. A second memory 43-2A that operates by a signal to set the set value M2 and a reference signal source 45A that includes a crystal oscillation circuit that outputs a reference frequency signal fref including a reference clock signal are provided. Yes. A first counting means (for example, a first counter) 44-1A is connected to the output side of the first memory 43-1A, and the first counter is also connected to the output side of the second memory 43-2A. A second counting means (for example, a second counter) 44-2A having the same characteristics as 44-1A is connected.

  The first counter 44-1A operates according to the control signal of the control circuit 13A, and counts the number of output clock signals of the oscillation circuit 42-1A by the number of times of the set value M1 set in the first memory 43-1A. The third counting means (for example, third counter) 44-3A is connected to the output side. The second counter 44-2A operates according to the control signal of the control circuit 13A, and counts the number of output clock signals of the oscillation circuit 42-2A by the number of times of the set value M2 set in the second memory 43-2A. The fourth counting means (for example, a fourth counter) 44-4A is connected to the output side.

  The third counter 44-3A is operated by the control signal of the control circuit 13A, and is output from the reference signal source 45A during the period in which the first counter 44-1A performs the count operation for the set value M1. The number of clocks of the reference frequency signal fref is counted, and this count number N1 is stored in the control circuit 13A. The fourth counter 44-4A has the same characteristics as the third counter 44-3A, operates according to the control signal of the control circuit 13A, and the second counter 44-2A performs the counting operation the number of times of the set value M2. During this period, the number of clocks of the reference frequency signal fref output from the reference signal source 45A is counted, and this count number N2 is stored in the control circuit 13A. The count number N1 corresponds to the set value M1, and the count number N2 corresponds to the set value M2.

(Configuration of FIG. 4)
4 is a circuit diagram showing a configuration example of the pressure detection sensor element 11B, the pressure detection circuit 12B, and the pressure control circuit 13B in FIG. 1, and is the same element as the element (numeral + A) in FIG. Are assigned a common code (same number + B).

  In the circuit of FIG. 4, instead of the sensor element 11A and the reference resistance element 41A made of the thermistor resistance of FIG. 3, a capacitive sensor element 11B and a reference capacitance element 41B are provided, and the tire 1 is formed using the sensor element 11B. The pressure is detected.

  In the circuit of FIG. 4, a control circuit 13B that outputs various control signals and pressure detection data for controlling each circuit block, and operates according to the control signal of the control circuit 13B, and has a capacitance value Cs of the sensor element 11B. A first oscillation circuit 42-1B that oscillates at a determined oscillation frequency, and a second oscillation circuit 42- that operates by a control signal of the control circuit 13B and oscillates at an oscillation frequency determined by a fixed capacitance value Cref of the reference capacitance element 41B. 2B, the first memory 43-1B which operates by the control signal of the control circuit 13B and sets the set value M1 which is the number of counts, and operates by the control signal of the control circuit 13B to set the set value M3. And a third memory 43-3B for providing the control circuit 13B with a count number N3 corresponding to.

  A second counter 44-2B is connected to the output side of the second oscillation circuit 42-2B and the first memory 43-1B. The second counter 44-2B operates according to the control signal of the control circuit 13B, and counts the number of output clock signals of the second oscillation circuit 42-2B by the number of times of the set value M1 in the first memory 43-1B. The first counter 44-1B is connected to the output side. The first counter 44-1B is operated by the control signal of the control circuit 13B, and the number of output clock signals of the first oscillation circuit 42-1B is set while the second counter 44-2B is counting. Counting is performed and the count number N1 is output to the control circuit 13B. The control circuit 13B has a function of outputting various control signals and pressure detection data (for example, count numbers N1 and N3).

(Operation of Example 1)
In the first embodiment, the following operations (1) to (5) are performed.

(1) Data Transmission Method of Reference Example As a reference example for the first embodiment, for example, the holding register 14, the second voltage determination circuit 20-2, and the second timer circuit 15- in the detection unit 10 of FIG. A sensor system without 2 is conceivable. The data transmission method in such a sensor system is executed by the following steps S1 to S5, for example.

  In step S 1, when a command or data for operating the detection unit 10 is output from the host device 38 in the reading device 30 of FIG. 1, the command or data is sent to the control circuit 36 via the interface 37. Under the control of the control circuit 36, the reading device 30 shifts to the operation mode. When the reading device 30 shifts to the operation mode, the modulation circuit 33 operates, and the control signal from the control circuit 36 is modulated by the carrier for power source output from the carrier oscillation circuit 32. When this modulated signal is converted into a transmission signal by the transmission circuit 34 and sent to the loop antenna 31, an alternating magnetic field is generated from the loop antenna 31.

  When the detection unit 10 embedded in the side portion of the tire 1 rotates together with the tire 1 and the antenna coil 16 of the detection unit 10 approaches the loop antenna 31, an AC electromotive voltage is induced in the loop antenna 16. The induced AC electromotive voltage is rectified by the rectifier circuit 18 to generate a DC power supply voltage, and the capacitor 19 is charged. The first voltage determination circuit 20-1 compares the received DC power supply voltage with the operation guarantee value of the detection unit 10, and determines whether or not the operable voltage of the detection unit 10 has been received. .

  In step S2, when it is determined that the first voltage determination circuit 20-1 has received a voltage equal to or higher than the operation guarantee value of the detection unit 10, the first voltage determination circuit 20-1 cancels the reset applied to the control circuit 13 and causes the control circuit 13 to operate. In addition to the initial state, the received DC power supply voltage is supplied to the control circuit 13 (power ring), and the detection unit 10 is shifted to the operation mode.

  In step S3, the clock is detected by the clock detection circuit 21 from the AC electromotive voltage induced in the antenna coil 16 by the transition to the operation mode and supplied to the control circuit 13, and the AC electromotive voltage is received by the receiving circuit. The command and data received from the demodulator 22 and demodulated are sent to the control circuit 13. Accordingly, the temperature control circuit 13A, the temperature detection circuit 12A and the temperature detection sensor element 11A in FIG. 3 in the control circuit 13, the pressure control circuit 13B, the pressure detection circuit 12B and the pressure detection in FIG. The sensor element 11B operates and the temperature and pressure of the tire 1 are detected.

In step S <b> 4, the temperature and voltage detection data of the tire 1 is output from the control circuit 13 and converted into, for example, the following transmission signal by the transmission circuit 23.
Transmission signal = synchronization signal + start signal +
Detection data + error detection and correction code + end signal

  In this transmission signal, a synchronization signal, a start signal, and an end signal are signals added for data transmission. In addition, the data transmission from the detection unit 10 operating in a non-contact manner to the reading device 30 may become unstable due to the influence of disturbance depending on the operating conditions. In order to correct this, an error detection correction code is provided. It has been added. Such a transmission signal is sent to the reading device 30 side through electromagnetic coupling between the antenna coil 16 and the loop antenna 31. The transmission signal sent to the reading device 30 side is received by the receiving circuit 35, demodulated, and sent to the control circuit 36. In the control circuit 36, predetermined calculation processing or the like is performed to calculate temperature detection data and pressure detection data, and the calculation results are sent to the host controller 38 via the interface 37.

  In step S5, after the detection data is transmitted from the detection unit 10 to the reading device 30 in step S4, the control circuit 13 is put into a waiting mode by the first timer circuit 15-1. The reason for providing the first timer circuit 15-1 is that when the detection unit 10 side repeatedly performs data detection and data transmission and transmits the detection data to the reading device 30 side without interruption, the reading device 30 side Since reception is difficult, when the data transmission is completed, the operation of the detection unit 10 is made to wait for a certain time.

  When the waiting time of step S5 elapses, the process returns to step S3, and the operations of step S3 → step S4 → step S5 are repeated. During this operation, when the power reception voltage on the detection unit 10 side becomes low and the operation cannot be performed, this is determined by the first voltage determination circuit 20-1, and the control circuit 13 enters the stop mode. The circuit 13 is reset and initialized.

Such a sensor system of the reference example has the following advantages (i) and (ii).
(I) The detection unit 10 can receive the power supplied from the reading device 30 in a non-contact manner and return detection data of the temperature and pressure of the tire 1 to the reading device 30 side.

  (Ii) When the distance between the reading device 30 and the detection unit 10 is increased and the magnetic field coupling is weakened so that the detection unit 10 cannot be operated, this is detected by the first voltage determination circuit 20-1 and enters the stop mode. So there is no malfunction or runaway.

  However, if the electromagnetic coupling between the reading device 30 and the detection unit 10 is unstable and power supply cannot be continuously supplied from the reading device 30 to the detection unit 10, the operation of the detection unit 10 is interrupted and reset. There is a drawback that it is easy to occur that detection data cannot be sent to the reading device 30 to the end.

  Therefore, in order to solve such a drawback, in the first embodiment, a holding register 14, a second timer circuit 15-2, and a second voltage determination circuit 20-2 are provided in the detection unit 10.

(2) Data Transmission Method of Sensor System in FIG. 1 The data transmission method in the sensor system of FIG. 1 is executed by, for example, the following steps SP1 to SP12.

  In step SP1, as in step S1, the reading device 30 shifts to the operation mode, a transmission signal is sent to the loop antenna 31, and an alternating magnetic field is generated from the loop antenna 31. When the detection unit 10 embedded in the tire 1 rotates together with the tire 1 and the antenna coil 16 of the detection unit 10 approaches the loop antenna 31, an AC electromotive voltage is induced in the loop antenna 16. The induced AC electromotive voltage is rectified by the rectifier circuit 18 to generate a DC power supply voltage, and the capacitor 19 is charged. The received DC power supply voltage is compared with the operation guarantee value of the sensor unit 10 by the first voltage determination circuit 20-1, and it is determined whether or not the operable voltage can be received and the second voltage. The determination circuit 20-2 compares the detected data with a value that can be held, and determines whether or not the voltage that is lower than the operation guarantee value but that can hold the detected data has been received.

  In step SP2, it is determined by the first voltage determination circuit 20-1 that a voltage equal to or higher than the guaranteed operation value could not be received, but the second voltage determination circuit 20-2 has a voltage lower than the guaranteed operation value. However, when it is determined that the voltage that can hold the detected data can be received, the reset applied to the control circuit 13 is released, the control circuit 13 is set to the initial state, and the holding register 14 is also initialized. Set to state.

  In step SP3, the circuit enters a holding mode in which the current consumption of the circuit is sufficiently smaller than in the case of the detection data transmission operation from the detection unit 10 to the reading device 30, and the detection data detected by the sensor element 11 and the detection circuit 12 is held. It is held in the register 14. Since the current consumption of the circuit is sufficiently small during the holding mode, the received DC power supply voltage may be low in order to maintain this holding mode. For a short time, even if the received voltage is completely lost, the holding mode can be maintained with the electric charge charged in the capacitor 19.

  In step SP4, the magnetic field coupling is increased, the received DC power supply voltage is increased, and the first voltage determination circuit 20-1 determines whether or not the voltage higher than the operation guarantee value has been received. .

  In step SP5, when the first voltage determination circuit 20-1 determines that the voltage higher than the operation guarantee value has been received, the detection unit 10 shifts from the holding mode to the operation mode, and the received DC power supply voltage is controlled. Supplyed to the circuit 13 (power ring), the detection unit 10 performs normal operation.

  In step SP6, the control circuit 13 checks the flag of the holding register 14.

  In step SP7, if the flag of the holding register 14 is set, it waits for a certain waiting time by the second timer circuit 15-2. The reason for putting a certain waiting time is to avoid the problem that it is determined that the abnormal data has been received as a series of operations as seen from the reading device 30 side when the time in the holding mode is extremely short. . That is, if there is a certain waiting time, it can be determined that the data transmission has been interrupted on the reading device 30 side, so that the problem can be avoided.

  In step SP8, if the flag is not set in step SP6, the temperature control circuit 13A, the temperature detection circuit 12A and the temperature detection sensor element 11A in FIG. 3 in the control circuit 13, and the pressure control circuit in FIG. 13B, the pressure detection circuit 12B and the pressure detection sensor element 11B operate, and the temperature and pressure of the tire 1 are detected.

  In step SP9, a data acquisition flag is added to the temperature and pressure detection data and stored in the holding register 14.

  In step SP10, after the processing in step SP7 or SP9, the detection data held in the holding register 14 is output from the control circuit 13, and is converted into a transmission signal by the transmission circuit 23 in the same manner as in step S4. The signal is sent to the reader 30 via the electromagnetic coupling of the loop antenna 31.

  In step SP11, after the detection data held in the holding register 14 is transmitted, the flag of the holding register 14 is initialized by the control circuit 13.

  In step SP12, it waits for a fixed waiting time by the first timer circuit 15-1. Thereafter, the process returns to step SP8.

  In the processing of steps SP1 to SP12 described above, when the magnetic field coupling becomes weak during the operation of steps SP6 to SP12, and it is determined by the first voltage determination circuit 20-1 that power cannot be received beyond the guaranteed operation value. , Transition to hold mode. Further, when the magnetic field coupling is further weakened during the holding mode in step SP3 and the second voltage determination circuit 20-2 determines that the voltage capable of holding the detected data cannot be received, the stop mode is set. Thus, the control circuit 13 is reset and initialized.

(3) Operation of FIG. 3 First, the first oscillation circuit 42-1A oscillates at a frequency corresponding to the resistance value Rth of the sensor element 11A by the control signal of the control circuit 13A, and the second oscillation circuit 42- 2A oscillates at a frequency corresponding to the resistance value Rref of the reference resistance element 41A by the control signal of the control circuit 13A. The set value M1 in the first memory 43-1A is loaded into the first counter 44-1A by the control signal of the control circuit 13A, and the second memory 43-2A is loaded by the control signal of the control circuit 13A. Is set to the second count 44-2A. The first and second counters 44-1A and 44-2A operate according to the control signal of the control circuit 13A, and the number of clock signals output from the first oscillation circuit 42-1A by the first counter 44-1A. And the number of clock signals output from the second oscillation circuit 42-2A is counted by the second count 44-2A.

  During the period in which the first counter 44-1A performs the count operation for the set value M1, the third counter 44-3A is operated by the control signal of the control circuit 13A, and the number of clocks of the reference frequency signal fref is counted. The count number N1 is stored in the control circuit 13A. At the same time, the fourth counter 44-4A is operated by the control signal of the control circuit 13A during the period when the second count 44-2A performs the count operation of the set value M2, and the number of clocks of the reference frequency signal fref is set. The count number N2 is stored in the control circuit 13A.

(4) Operation of FIG. 4 First, the set value M1 in the first memory 43-1B is loaded into the second counter 44-2B by the control signal of the control circuit 13B, and at the same time by the control signal of the control circuit 13B. The first oscillation circuit 42-1B oscillates at an oscillation frequency determined by the capacitance value Cs of the sensor element 11B, and the second oscillation circuit 42-2B oscillates at an oscillation frequency determined by the capacitance value Cref of the reference capacitance element 31B. The number of clock signals output from the second oscillation circuit 42-2B is counted by the second counter 44-2B operated by the control signal of the control circuit 13B.

  During the period in which the second counter 44-2B performs the count operation for the set value M1, the first counter 44-1B is operated by the control signal of the control circuit 13B and is output from the first oscillation circuit 42-1B. The number of clock signals to be counted is counted, and this count number N1 is stored in the control circuit 13B.

  When the operations (3) and (4) are completed, the third and fourth counters 44-3A and 34-4A are reset by the control signal of the control circuit 13A shown in FIG. 3, and the control shown in FIG. The first counter 44-1B is reset by the control signal of the circuit 13B. Then, the detection data such as the count numbers N1, N2 in FIG. 3 stored in the control circuit 13A is converted into a transmission signal by the transmission circuit 17, and the reading device 30 side through the electromagnetic coupling of the antenna coil 16 and the loop antenna 31. Sent to.

  (5) FIG. 5 is a time chart showing the data transmission method of FIG. 1 compared with the reference example. The horizontal axis in FIG. 5 is time.

  As shown in FIG. 5, in the sensor system of the reference example, one operation (51) from the detection unit 10 to the reading device 30 is (detection operation (51a) + detection data transmission operation (51b)). When the duration of power supply (power ring) from the reading device 30 to the detection unit 10 is sufficiently long (50-1), for example, two operations (51, 51) are performed. Although the duration of the power ring is long (50-2), the power reception voltage of the detection unit 10 decreases during transmission (50-2a), or when power reception is interrupted (50-2b), transmission is performed during operation. Even if the power receiving voltage increases, the remaining time of the power ring is too short to transmit the detection data. In addition, when the duration of the power ring is short (50-3) and power reception is interrupted for a short time during transmission (50-3a), the detection data cannot be transmitted.

  On the other hand, in the sensor system of the first embodiment, when the duration of the power ring is sufficiently long (50-1), as in the reference example, (detection operation (52a) + detection data transmission operation (52b)) One operation (52) is performed twice, for example. Although the duration of the power ring is long (50-2), if the power reception voltage of the detection unit 10 decreases during transmission (50-2a), or the power reception is interrupted (50-2b), the power reception voltage decreases. (50-2a) enters the holding mode (52c), and the detected data is held in the holding register 14. Even if there is a brief interruption of power reception (50-2b) during this holding mode, the accumulated charge in the capacitor 19 Can maintain the holding mode. Thereafter, when the power receiving voltage rises and the operation mode is shifted to, the detection data held in the holding register 14 is transmitted, so that the transmission operation (52) can be completed. Further, when the duration of the power ring is short (50-3) and the power reception is interrupted for a short time during transmission (50-3a), the held data (52d) is set by the accumulated charge of the capacitor 19 and the detection data is stored. Since the detection data held in the holding register 14 and held after the power receiving state is restored, the transmission operation (52) can be completed.

(Effect of Example 1)
According to the first embodiment, there are the following effects (A) to (C).

(A) Effect of FIG. 1 In the sensor system of the first embodiment, when the magnetic field coupling is strong and the received voltage of the detection unit 10 is sufficiently high, the following steps ST1 to ST4 are sequentially executed to perform steps ST2 to ST4. Repeat the process.

  The detection unit 10 receives the power supply voltage and initializes the internal operation (step ST1) → temperature detection / pressure detection of the tire 1 (step ST2) → transmission of detection data (step ST3) → first timer circuit 15-1 (Step ST4) → Return to step ST2.

  If the received voltage is completely lost during the operation of the detection unit 10 or if the received voltage becomes very weak and even the detection data cannot be held, the control circuit 13 is reset by the second voltage determination circuit 20-2. Hang and enter stop mode. Thereafter, when the power supply voltage is received, the operation is restarted from step ST1. When the magnetic field coupling becomes weak during execution of step ST3 and the received voltage becomes low, and the detection data detected in step ST2 can be held, the second voltage determination circuit 20-2 makes it more than in step ST3. The holding mode in which the current consumption of the circuit is sufficiently small is set, and the detection data is held in the holding register 14. When the magnetic field coupling strength is recovered and the power reception voltage is increased, the second timer circuit 15-2 executes the process from the beginning of step ST3 after a certain waiting time, and transmits the detection data held in the holding register 14. It has become. Therefore, there are the following effects (a) to (d).

    (A) Even when the power receiving time on the detection unit 10 side is short and a series of operation sequences cannot be completed at once, the operation can be continued after the power receiving state is recovered.

    (B) After transmission is interrupted, it resumes from where the detection data held in the hold mode is sent, so the time required to continue supplying the necessary power supply voltage until the detection data is sent is reduced. I can do it.

    (C) Even when the drive magnetic field is interrupted for a short time, the signal waiting time of the second timer circuit 15-2 is not transmitted, so that it can be determined that the signal transmission is interrupted on the reading device 30 side. Don't accidentally receive and receive a series of data.

    (D) Since the original data is sent for reception on the reading device 30 side, no special processing is required.

(B) Effects of FIGS. 3 and 4 A combination of the sensor elements 11A and 11B and the oscillation circuits 42-1A and 42-1B, and the reference resistance element 41A and the reference capacitance element 41B and the oscillation circuits 42-2A and 42-2B. Since the temperature and pressure of the tire 1 are detected in combination, the initial adjustment (that is, offset adjustment) can be made to a predetermined condition (count number N1 = N2) even if the oscillation frequency in the initial state varies. A combination of the sensor elements 11A and 11B and the oscillation circuits 32-1A and 42-1B is used to set temperature detection data and pressure detection data (count value) when a predetermined temperature or pressure change is applied to a predetermined value (= N2 -N1) (ie full scale adjustment). Furthermore, oscillation circuits 42-1A, 42-2A or 42-1B, 42-2B having the same characteristics are used for the oscillation by the sensor elements 11A and 11B and the oscillation by the reference resistance element 41A and the reference capacitance element 41B. Is detected relatively, even if the oscillation frequency changes at the same rate due to fluctuations in the characteristics of the oscillation circuits 42-1A, 42-2A or 42-1B, 42-2B, it is canceled and influenced. Therefore, the oscillation circuits 42-1A, 42-2A or 42-1B, 42-2B are not easily affected by variations and fluctuations.

  FIG. 6 is a schematic perspective view showing another application example of the sensor system showing Embodiment 2 of the present invention.

  In this application example, in a device that loads and transports a product 61 on a rotating conveyor 60, a detection unit 10A for temperature detection is mounted on the conveyor 60, and a reading device 30 is disposed in the vicinity of the conveyor 60 to detect it. The detected temperature data of the conveyor 60 detected by the unit 10A is transmitted to the reading device 30 in a non-contact manner. Even in such a sensor system, the same operational effects as those of the first embodiment can be obtained.

  FIG. 7 is a schematic perspective view showing another application example of the sensor system showing the third embodiment of the present invention.

  In this application example, temperature, pressure, PH, etc. are detected in the ball-shaped carrier 71 in an apparatus for flowing (rolling) the ball-shaped carrier 71 together with the liquid 72 that is normally flowed into the resin-made piping 70. A detection unit 10B is provided. Instead of the loop antenna 31 of the reading device 30, antenna coils 31 </ b> B are wound around the detection areas 73 arranged at a plurality of locations of the pipe 70. In this apparatus, when the ball-shaped carrier 71 comes in the reading area 73, the reading device 30 and the detection unit 10B are contacted by the magnetic field coupling between the antenna coil 31B of the reading device 30 and the antenna coil 16 of the detection unit 10. The power supply is supplied and the detection unit 10B operates.

  Since the ball-shaped carrier 71 rotates (rolls), if the direction of receiving the magnetic field of the antenna coil 16 on the detection unit 10B side and the direction of the driving magnetic field from the loop antenna 31B on the reading device 30 side are completely orthogonal, Even if it exists, since the induced electromotive voltage does not generate | occur | produce in the antenna coil 16, the detection unit 10B cannot operate | move and a drive magnetic field will be interrupted. Even in such a case, if the data transmission method of the third embodiment is used, the detection data of the detection unit 10B can be accurately transmitted to the reading device 30.

  The present invention is not limited to the illustrated first to third embodiments, and various modifications and usage forms are possible. Examples of such modifications and usage forms include the following (a) to (d).

  (A) The detection units 10, 10A, 10B and the reading device 30 can be changed to other circuit configurations than those shown in the figure. For example, in FIGS. 3 and 4, the reference resistance element 41 </ b> A and the reference capacitance element 41 </ b> B whose electric characteristic values are constant with respect to the change in the physical quantity is used as the reference element. However, other elements having different electrical characteristic values from the sensor elements 11A and 11B may be used, and the circuit configurations of FIGS. 3 and 4 may be changed correspondingly. In FIGS. 3 and 4, two oscillation circuits of the first oscillation circuits 42-1A and 42-1B and the second oscillation circuits 42-2A and 42-2B are used. One common oscillation circuit may be provided, and this may be changed to a configuration that is switched by a switching unit.

  (B) The detection units 10, 10A, and 10B and the reader 30 are configured to exchange power and signals by magnetic field coupling, but may be changed to other non-contact coupling methods such as radio wave coupling.

  (C) In FIG. 1, the sensor element 11A for temperature detection and the sensor element 11B for pressure detection are used as the sensor element 11, the detection unit 10A for temperature detection is used in FIG. 6, and in FIG. Although the detection unit 10B that detects pressure, PH, etc. is used, various things such as stress, displacement, acceleration, electric quantity, etc. apply in addition to temperature, pressure, PH as physical quantities of the moving detection object I can do it.

  (D) The sensor system according to the present invention is not limited to the tire 1, the conveyor 50, and the pipe 70 of the vehicle. Applicable to devices and systems.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the sensor system which shows Example 1 of this invention. It is a perspective view which shows the tire of the vehicle to which the sensor system of FIG. 1 is applied. FIG. 2 is a circuit diagram showing a configuration example of a temperature detection sensor element 11A, a temperature detection circuit 12A, and a temperature control circuit 13A in FIG. FIG. 2 is a circuit diagram illustrating a configuration example of a pressure detection sensor element 11B, a pressure detection circuit 12B, and a pressure control circuit 13B in FIG. It is a time chart which shows the data transmission method of FIG. 1 compared with the reference example. It is a schematic perspective view which shows the other application example of the sensor system which shows Example 2 of this invention. It is a schematic perspective view which shows the other application example of the sensor system which shows Example 3 of this invention.

Explanation of symbols

1 tire 10, 10A, 10B detection unit 11, 11A, 11B sensor element 12, 12A, 12B detection circuit 13, 13A, 13B control circuit 14 holding register 15-1, 15-2 timer circuit 16, 31B antenna coil 18 rectifier circuit 19 Capacitors 20-1, 20-2 Voltage determination circuit 22, 35 Reception circuit 23, 34 Transmission circuit 30 Reading device 31 Loop antenna 60 Conveyor 70 Piping 71 Carrier

Claims (9)

Mounted on a moving detection target, receives power supply power supplied from the outside and receives a control signal, and detects a change in a physical quantity in the detection target based on the received power supply power and the received control signal. A detection unit that transmits detection data to the outside,
The control signal, which is installed apart from the detection unit, is non-contact with the detection unit, is superimposed on the power supply power, is transmitted to the detection unit, and the detection data transmitted from the detection unit is transmitted. A reader to receive;
A data transmission method in a sensor system comprising:
The detection unit determines the magnitude of the received power supply power,
When the determination result is equal to or higher than the operation guarantee value, the detection unit is set to an operation mode and the detection data is transmitted to wait for a certain time,
When the determination result is smaller than the guaranteed operation value but greater than or equal to a value that can hold the detected data, the detection unit is set to a retention mode to retain the detected data, and the determined result is equal to or greater than the guaranteed operation value. When recovered to, the transition from the holding mode to the operation mode, the detection data held in a certain waiting time is transmitted,
When the determination result is smaller than a value that can hold the detection data, the data transmission method is set to stop mode and the operation of the detection unit is stopped.   The data transmission method according to claim 1, wherein the detection unit and the reading device exchange signals by non-contact magnetic field coupling.   The data transmission method according to claim 1, wherein the detection unit mounted on the detection object is circulated with respect to the reading device and communication is repeated. Mounted on a moving detection target, receives power supply power supplied from the outside and receives a control signal, and detects a change in a physical quantity in the detection target based on the received power supply power and the received control signal. A detection unit that transmits detection data to the outside,
The control signal, which is installed apart from the detection unit, is non-contact with the detection unit, is superimposed on the power supply power, is transmitted to the detection unit, and the detection data transmitted from the detection unit is transmitted. A reader to receive;
A sensor system comprising:
The detection unit is
Determination means for determining the magnitude of the received power supply power and outputting a determination result;
A first setting means for setting the detection unit to an operation mode and transmitting the detection data to wait for a predetermined time when the determination result is equal to or greater than an operation guarantee value;
A second setting means for setting the detection unit to a holding mode and holding the detection data when the determination result is smaller than the operation guarantee value but not less than a value capable of holding the detection data;
When the determination result in the holding mode is restored to the operation guarantee value or more, a third setting means for shifting from the holding mode to the operation mode and transmitting the held detection data after a certain waiting time;
A fourth setting means for setting the detection unit to a stop mode and stopping the operation of the detection unit when the determination result is smaller than a value that can hold the detection data;
A sensor system comprising:   The determination unit determines a magnitude of the converted DC power and outputs a determination result by rectifying a circuit that converts the received power source power into DC power, a storage unit that stores the converted DC power, 5. The sensor system according to claim 4, wherein the sensor system is configured by a determination circuit.   6. The sensor system according to claim 4, wherein the fixed time and the fixed waiting time are measured by a timer circuit.   The sensor system according to claim 4, wherein the detection data is held in a holding register.   The sensor system according to claim 4, wherein the detection unit and the reading device exchange signals by non-contact magnetic field coupling.   The sensor system according to any one of claims 4 to 8, wherein the detection unit mounted on the detection object is circulated with respect to the reading device and communication is repeated.

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