JP2016022889A - Tire condition monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire condition monitoring device capable of reducing a power consumption.SOLUTION: A tire condition monitoring device is provided for a vehicle which has a plurality of wheels having tires mounted on wheel parts, and configured to monitor states of the tires. The tire condition monitoring device includes: an antenna for receiving signals; a reception part capable of receiving a signal having a frequency band equal to or higher than the ultrahigh frequency band; and an electric power recovery part which can recover electric power from the signal received by the antenna, and supply the recovered electric power at least to the reception part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire condition monitoring device for monitoring the condition of a tire.

  A plurality of wheels having tires mounted on a wheel portion are provided in a vehicle, and a wireless tire state monitoring device has been proposed as a device that can monitor the state of the tire. This tire condition monitoring device includes a tire sensor unit (wheel side unit) provided in a tire of each wheel of the vehicle, and a receiver (vehicle body side unit) provided on the vehicle body of the vehicle. The tire sensor unit for each wheel is configured to include a transmitter, and the transmitter wirelessly transmits a transmission signal related to the detected tire state. And a receiver displays the information regarding a tire pressure on the indicator provided in the vehicle interior as needed based on the transmission signal from each transmitter.

  In such a tire condition monitoring device, for example, as shown in Patent Document 1, the position of a wheel is specified by a trigger signal transmitted from a receiver. When the receiver determines the position of the wheel, it transmits a trigger signal to the transmitter. The transmitter that has received the trigger signal outputs a response signal to the receiver, and the receiver that has received the response signal specifies the position of the wheel according to the response signal.

JP 2010-143485 A

  By the way, in the tire condition monitoring devices such as these, since the tire sensor unit is provided in the tire, power is supplied from the battery or the like, but the power consumption is reduced from the viewpoint of extending the life of the battery or the like. Is desired.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a tire state detection device capable of reducing power consumption.

  A tire condition monitoring apparatus that solves the above problems is a tire condition monitoring apparatus that is provided in a vehicle including a plurality of wheels with tires mounted on a wheel portion, and that monitors the condition of the tire, and receives a signal. An antenna, a receiving unit capable of receiving a signal in a frequency band of ultra-high frequency or higher from the antenna, and recovering power from a signal received by the receiving unit and supplying at least the recovered power to the receiving unit It is summarized that the power recovery unit is provided.

  According to this, the receiving unit can receive a signal in a frequency band of ultra-high frequency or higher, and power collected from the signal can be supplied to at least the receiving unit, so that power consumption can be reduced.

  About the tire condition monitoring device, the receiving unit can be controlled to a standby state, cancels the standby state according to a trigger signal from a receiver, and the power recovery unit recovers power from the trigger signal. It is good also as a structure.

According to this, while being able to control a receiving part to a standby state, electric power can be collect | recovered from the trigger signal from which a standby state is cancelled | released, and power consumption can be reduced.
The tire condition monitoring device includes a control unit that performs control for monitoring the condition of the tire in response to reception of the signal, and whether the reception unit has received a signal that satisfies a predetermined reception condition. When the determination unit determines that the signal satisfying the reception condition is received, the control unit outputs information indicating reception of the signal to the control unit, and the determination unit determines whether the reception condition is It is good also as a structure which has an information output part which performs control which does not output the information which shows reception of a signal to the said control part, when it determines with having received the signal which is not materialized.

  According to this, only when a signal that satisfies a predetermined reception condition is received, the information indicating the reception of the signal is output to the control unit. It is possible to reduce both the power consumption due to the input.

About the said tire state monitoring apparatus, while the said control part can be controlled to a standby state, it is good also as a structure which cancels | releases a standby state according to the information which shows reception from the said receiving part.
According to this, when the control unit can be controlled to be in a standby state and a signal that satisfies a predetermined reception condition is received, information indicating reception of the signal is input, and the standby state is released. , Power consumption can be reduced.

  According to the present invention, power consumption can be reduced.

The schematic block diagram which shows the vehicle by which the tire condition monitoring apparatus is mounted. The block diagram which shows the structure of a wheel side unit. The circuit diagram which shows the structure of an electric power collection | recovery circuit. The figure which shows arrangement | positioning of an antenna group typically. (A) is a figure which shows the state which gave the directivity to the antenna group right front, (b) is a figure which shows the state which gave the directivity to the antenna group on the left back. The figure which shows the control timing according to various trigger signals.

Hereinafter, an embodiment of a tire condition monitoring device will be described.
As shown in FIG. 1, the tire condition monitoring device 10 includes four wheel side units 20 that are respectively attached to four wheels 12 of the vehicle 11, and a vehicle body side unit 30 that is installed on the vehicle body of the vehicle 11. . Further, the vehicle 11 is equipped with a control device 13 that comprehensively controls operations of the vehicle 11 such as starting and stopping of the engine. The control device 13 is connected to an ignition switch 14 that allows the driver of the vehicle 11 to start and stop the engine.

  Each wheel 12 includes a wheel portion 15 and a tire 16 attached to the wheel portion 15. The wheel side unit 20 is attached to the wheel portion 15 to which the tire 16 is attached so as to be disposed in the internal space of the tire 16. Each wheel side unit 20 detects the state of the corresponding tire 16 (in-tire pressure, in-tire temperature), and wirelessly transmits a signal (data signal and response signal) including data indicating the detected tire state.

  As shown in FIG. 2, each wheel side unit 20 includes a pressure sensor 21, a temperature sensor 22, a wheel side controller 23, a transmission circuit 24, a trigger reception circuit 25, a wheel side antenna 26, a switch 27, a battery 28, and a power recovery circuit. 29. Among the members of the wheel side unit 20, the trigger receiving circuit 25 is operated by the power from the power recovery circuit 29 as the power recovery unit, and the other members are operated by the power of the battery 28.

  The pressure sensor 21 detects the pressure in the corresponding tire 16 (in-tire pressure), and outputs the in-tire pressure data obtained by the detection to the wheel-side controller 23. The temperature sensor 22 detects the temperature in the corresponding tire 16 (in-tire temperature), and outputs the in-tire temperature data obtained by the detection to the wheel-side controller 23.

  The wheel side controller 23 includes a microcomputer 23a and a memory 23b (RAM, ROM, etc.), and an ID code that is identification information unique to each wheel side unit 20 is registered in the memory 23b. This ID code is information used to identify each wheel side unit 20 in the vehicle body side unit 30 and is included in a signal transmitted from the wheel side controller 23. The wheel-side controller 23 outputs data including tire pressure data, tire temperature data, and an ID code to the transmission circuit 24. The transmission circuit 24 serving as a transmission unit generates a signal that is a modulated signal by modulating data from the wheel-side controller 23, and wirelessly transmits the signal from the wheel-side antenna 26. From the transmission circuit 24, a data signal periodically transmitted to the vehicle body side unit 30 and a response signal transmitted in response to the trigger signal from the vehicle body side unit 30 are transmitted.

  The trigger receiving circuit 25 receives a trigger signal and a sleep signal transmitted from the vehicle body side unit 30 via the wheel side antenna 26 and the power recovery circuit 29. When receiving the trigger signal and the sleep signal, the trigger receiving circuit 25 demodulates the trigger signal and the sleep signal and sends them to the wheel-side controller 23.

  In the present embodiment, the trigger reception circuit 25 determines whether or not the received signal satisfies a predetermined reception condition. The reception condition includes a signal (radio wave) in a frequency band defined for the wheel side unit 20 and includes a signal for the wheel side unit 20. When it is determined that the received signal satisfies the reception condition, that is, when it is determined that the received signal is a signal for the wheel side unit 20, the trigger receiving circuit 25 demodulates the signal, and the wheel side controller 23. On the other hand, if the trigger reception circuit 25 determines that the received signal does not satisfy the reception condition, the trigger reception circuit 25 does not send a signal to the wheel-side controller 23.

  Further, as shown in FIG. 3, the power recovery circuit 29 outputs a signal received by the wheel side antenna 26 to the trigger receiving circuit 25 and can supply the power recovered from the signal to the trigger receiving circuit 25. Circuit. In the present embodiment, the power recovery circuit 29 includes a half-wave rectifier circuit in which a diode D and a capacitor C are connected in parallel between the input terminal T1 connected to the wheel-side antenna 26 and the ground GND. The trigger receiving circuit 25 is connected to the output terminals T2 and T3.

  The trigger receiving circuit 25 executes various processes such as demodulation and determination of a signal when the trigger signal is input. When the various processes accompanying the input of the trigger signal are finished, the trigger receiving circuit 25 controls the standby state. The standby state is a state in which input of a trigger signal is awaited, and is a state in which power consumption is lower than in a normal state. When the trigger signal is input in the standby state, the trigger receiving circuit 25 controls to the normal state. Therefore, the trigger receiving circuit 25 functions as a receiving unit, a determining unit, and an information output unit.

  As shown in FIG. 2, the switch 27 connects the wheel-side antenna 26 and the transmission circuit 24 or the trigger reception circuit 25. The wheel side antenna 26 is directly connected to the power recovery circuit 29 because the power recovery circuit 29 is connected to the trigger receiving circuit 25. The switch 27 is controlled to be switched by the wheel-side controller 23. By switching the switch 27, the wheel side antenna 26 is switched to a state where it is connected to either the transmission circuit 24 or the trigger reception circuit 25.

  The wheel-side controller 23 of each wheel-side unit 20 periodically performs a tire state measurement operation at a first predetermined time interval (for example, every 1 to 15 seconds) while the ignition switch 14 is on, while transmitting a data signal. The operation is periodically performed at a second predetermined time interval (for example, one minute interval) longer than the first predetermined time interval. The switch 27 is switched so that the wheel side antenna 26 and the transmission circuit 24 are connected when a data signal transmission operation is performed. On the other hand, when the data signal transmission operation is not performed, the switch 27 is switched so that the trigger receiving circuit 25 and the wheel-side antenna 26 are connected.

  The wheel-side controller 23 does not perform the tire state measurement operation and the data signal transmission operation while the ignition switch 14 of the vehicle 11 is off. The switch 27 is switched so that the trigger receiving circuit 25 and the wheel side antenna 26 are connected while the ignition switch 14 is off.

  In the present embodiment, the wheel-side controller 23 determines that the ignition switch 14 is turned on when the trigger signal is received. Further, when the sleep signal is received, the wheel controller 23 determines that the ignition switch 14 is turned off.

  Further, the wheel-side controller 23 as the control unit periodically performs a tire state measurement operation at a first predetermined time interval and periodically performs a data signal transmission operation at a second predetermined time interval. When the transmission operation is completed, the standby state is controlled. The standby state is a state of waiting until the next processing is executed, and is a state in which power consumption is lower than that in the normal state. The wheel-side controller 23 controls to the normal state when it is time to execute the next process in the standby state.

  Further, when the trigger signal and the sleep signal are input from the trigger receiving circuit 25, the wheel-side controller 23 executes a process corresponding to the signal, but when the process ends, the wheel-side controller 23 controls to a standby state. And the wheel side controller 23 will control to a normal state, if a trigger signal and a sleep signal are input in a standby state.

  As shown in FIG. 1, the vehicle body side unit 30 is installed closer to the front than the center in the front-rear direction of the vehicle body, and operates with electric power from a power source (not shown) of the vehicle 11. The vehicle body side unit 30 includes a box-shaped case 31, and an antenna group 32 is built in the case 31.

  The vehicle body side unit 30 includes a vehicle body side controller 33, a reception circuit 34, a trigger transmission circuit 35, and a switch 36 in a case 31. The vehicle body side unit 30 includes an alarm device 37 and a display device 38. The vehicle body side controller 33 includes a microcomputer 33a and a memory 33b, and comprehensively controls the operation of the vehicle body side unit 30. The vehicle body side controller 33 is wired or wirelessly connected to the control device 13 and grasps the on / off state of the ignition switch 14 via the control device 13.

  The receiving circuit 34 demodulates the data signal and the response signal (modulated signal) received from each wheel side unit 20 through the antenna group 32 and sends the demodulated signal to the vehicle body side controller 33. The vehicle body side controller 33 grasps the tire internal pressure and the tire internal temperature of the tire 16 corresponding to the transmitting wheel side unit 20 based on the data signal and the response signal from the receiving circuit 34.

  The trigger transmission circuit 35 as a trigger transmission unit generates a signal (trigger signal and sleep signal) in response to a request from the vehicle body side controller 33 and transmits the signal from the antenna group 32. In the present embodiment, the trigger transmission circuit 35 transmits a trigger signal when the vehicle body side controller 33 detects that the ignition switch 14 of the vehicle 11 is turned on (when the ignition switch 14 is turned on). The trigger transmission circuit 35 also transmits a trigger signal at a predetermined cycle (for example, 1 hour) when the ignition switch 14 is on. The trigger transmission circuit 35 transmits a sleep signal when the vehicle body side controller 33 detects that the ignition switch 14 of the vehicle 11 is turned off (when the ignition switch 14 is turned off). The trigger signal is a signal requesting the wheel side unit 20 to transmit a response transmission, and the sleep signal is a signal notifying the wheel side unit 20 that the ignition switch 14 has been detected to be off.

  The vehicle body side controller 33 causes the display 38 to display information on the tire internal pressure and the tire internal temperature. The indicator 38 is disposed in the visible range of the passenger of the vehicle 11 such as in the passenger compartment. The vehicle body controller 33 further notifies an alarm (notifier) 37 of an abnormality in the tire pressure or the tire temperature. As the alarm device 37, for example, a device for notifying abnormality by lighting or blinking of light or a device for notifying abnormality by sound is applied. In the present embodiment, the transmission circuit 24, the trigger reception circuit 25, the reception circuit 34, and the trigger transmission circuit 35 perform communication using a frequency in the 2.4 GHz band.

  As shown in FIG. 4, the antenna group 32 includes a first vehicle body side antenna 41, a second vehicle body side antenna 42, a third vehicle body side antenna 43, and a fourth vehicle body side antenna 44. Each of the first vehicle body side antenna 41 to the fourth vehicle body side antenna 44 is an L-shaped monopole antenna. The first vehicle body side antenna 41 to the fourth vehicle body side antenna 44 are gathered around the central axis L in the case 31 of the vehicle body side unit 30 with an equiangular (90 degrees) interval. As for the 1st vehicle body side antenna 41-the 4th vehicle body side antenna 44, the L-shaped short side parts 41a-44a each extend in the height direction (z-axis direction), and the L-shaped long side parts 41b-44b are the same plane ( (xy plane).

  The first vehicle body side antenna 41 and the third vehicle body side antenna 43 are arranged so as to face each other in the left-right direction, and the long sides 41b, 43b are arranged so that the longitudinal direction extends in the front-rear direction. Further, the second vehicle body side antenna 42 and the fourth vehicle body side antenna 44 are disposed so as to face each other in the front-rear direction, and the long sides 42b, 44b are disposed so that the longitudinal direction extends in the left-right direction. Feeding points 41 c to 44 c are provided on the short side portions 41 a to 44 a of the first vehicle body side antenna 41 to the fourth vehicle body side antenna 44.

  As shown in FIG. 1, a phase control circuit 39 is connected to the feeding points 41c to 44c. When the position of the wheel 12 is specified, the phase control circuit 39 receives a command from the vehicle body side controller 33 and adds a command to the pair of opposite vehicle body side antennas from the first vehicle body side antenna 41 to the fourth vehicle body side antenna 44. Power is supplied to a state that causes a phase difference in either minus.

  As shown in FIG. 5A, in the state in which a predetermined positive phase difference is generated between the first vehicle body side antenna 41 and the third vehicle body side antenna 43, the antenna group 32 moves rightward (FR). The antenna gain G (indicated by a two-dot chain line in FIG. 5A) can be increased, and directivity can be imparted in the front right (FR) direction.

  On the other hand, as shown in FIG. 5B, when a predetermined negative phase difference is generated between the first vehicle body side antenna 41 and the third vehicle body side antenna 43, the antenna group 32 causes the rear left ( The antenna gain G (indicated by a two-dot chain line in FIG. 5B) can be increased in the (RL) direction, and directivity can be provided in the left rear (RL) direction.

  Further, in a state where a predetermined positive phase difference is generated between the second vehicle body side antenna 42 and the fourth vehicle body side antenna 44, directivity in the right rear (RR) direction is increased by the increased antenna gain G. You can have it. On the other hand, in a state where a predetermined negative phase difference is generated between the second vehicle body side antenna 42 and the fourth vehicle body side antenna 44, it is opposite to the right rear (RR) direction due to the increased antenna gain G. Directivity can be provided in the left front (FL) direction.

Next, a method for specifying the position of the wheel 12 will be described.
In the following description, for convenience of explanation, the ID code of the wheel side unit 20 provided on the right front wheel 12 (FR) is 1, and the ID code of the wheel side unit 20 provided on the left front wheel 12 (FL) is 2. The ID code of the wheel side unit 20 provided on the right rear wheel 12 (RR) is 3, and the ID code of the wheel side unit 20 provided on the left rear wheel 12 (RL) is 4.

  When the position of the wheel 12 is specified, a trigger signal is sequentially transmitted to each wheel 12 with the antenna group 32 having directivity toward each wheel 12. When a trigger signal is transmitted from the wheel side unit 20 with directivity in the right front direction of the antenna group 32, the wheel side unit 20 provided on the wheel 12 in the right front direction receives the trigger signal and sends a response signal. While transmitting (returning) to the vehicle body side unit 30, the wheel side unit 20 provided in the other wheel 12 does not transmit a response signal. And the vehicle body side controller 33 can specify from the ID code contained in the received response signal that the wheel side unit 20 with the ID code 1 is provided on the right front wheel 12 (FR).

  When a trigger signal is transmitted with directivity in the left front direction of the antenna group 32, a response signal is transmitted from the wheel side unit 20 provided on the wheel 12 in the left front direction to the vehicle body side unit 30, and the vehicle body side controller 33. Can be specified that the wheel side unit 20 of the ID code 2 is provided on the front left wheel 12 (FL).

  Furthermore, the vehicle body side controller 33 is provided with the wheel side unit 20 of the ID code 3 on the wheel 12 (RR) on the right rear side by transmitting the trigger signal in order in the right rear and the left rear, and the ID code 4 The wheel side unit 20 can be specified as being provided on the left rear wheel 12 (RL). Therefore, the vehicle body side controller 33 functions as the specifying unit.

Next, the operation of the tire condition monitoring device 10 of the present embodiment will be described.
When the position of the wheel 12 is specified, a trigger signal is transmitted in a state where the antenna group 32 has directivity toward each wheel 12 (a state where the antenna gain G is increased toward each wheel 12). A trigger signal can be transmitted to each wheel side unit 20. And it has specified that the wheel side unit 20 which transmitted the response signal in response to the trigger signal is provided in that direction (direction in which the antenna gain G is increased).

  For this reason, a trigger signal can be transmitted to each wheel 12 by changing the directivity of the antenna group 32. Therefore, the vehicle body side antennas 41 to 44 can be collectively arranged at one place, and it is not necessary to provide an individual antenna for each of the plurality of wheels 12.

  Thus, in the wheel side unit 20, when a trigger signal is input, the electric power collection circuit 29 which collects electric power from the trigger signal is provided, and the trigger reception circuit 25 operates by the collected electric power. For this reason, the power consumption by the trigger receiving circuit 25 can be reduced, and the power consumption by the wheel side unit 20 can be reduced accordingly.

  As shown in FIG. 6, when a trigger signal is input at the timing indicated by reference symbol T11 in the trigger receiving circuit 25, the standby state is controlled from the standby state at the timing indicated by reference symbol T12 according to the input, Various processes are executed. In particular, when it is determined that the input trigger signal is a signal (radio wave) in a specified frequency band, such as a signal satisfying the reception condition (reception condition is satisfied), the trigger side receiving circuit 25 to the wheel side controller 23 Then, the demodulated trigger signal is output. Thus, when a trigger signal is input in the wheel-side controller 23, the standby state is controlled to the normal state at the timing indicated by reference numeral T13 in accordance with the input, and various processes are executed.

  On the other hand, in the trigger receiving circuit 25, a trigger signal is input at the timing indicated by reference numeral T21, and is controlled from the standby state to the normal state at the timing indicated by reference numeral T22, and the input trigger signal is not a signal that satisfies the reception condition. If it is determined that the reception condition is not satisfied, the trigger signal demodulated from the trigger receiving circuit 25 to the wheel-side controller 23 is not output. As a result, no trigger signal is input in the wheel-side controller 23, and the standby state is not controlled to the normal state at the timing indicated by reference numeral T23.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The trigger receiving circuit 25 can receive a signal in a frequency band of ultra-high frequency or higher including a communication frequency in the 2.4 GHz band, and the power recovery circuit 29 collects at least the trigger receiving circuit 25 from the signal. Power can be supplied, and power consumption can be reduced.

  (2) Further, as compared with the case where communication is performed using an antenna of an electromagnetic induction method or a magnetic resonance method using a frequency in a low frequency band, the power consumption in the standby state in the wheel side unit 20 is reduced. The side antenna 26 and the vehicle body side antennas 41 to 44 can be downsized, and the trigger signal communication distance can be increased.

  (3) The transmission circuit 24 and the trigger reception circuit 25 of the wheel side unit 20 and the reception circuit 34 and the trigger transmission circuit 35 of the vehicle body side unit 30 communicate using a frequency of 2.4 GHz band. That is, since communication is performed using the same frequency, the transmission circuit 24 and the trigger reception circuit 25 can share the wheel-side antenna 26, and the reception circuit 34 and the trigger transmission circuit 35 include the antenna group 32 ( The first vehicle body side antenna 41 to the fourth vehicle body side antenna 44) can be shared. Therefore, the number of parts is reduced as compared with the case where individual antennas are used for the transmission circuit 24, the trigger reception circuit 25, the reception circuit 34, and the trigger transmission circuit 35, respectively.

(4) The trigger receiving circuit 25 can be controlled to the standby state, and power can be recovered from the trigger signal for releasing the standby state, so that power consumption can be reduced.
(5) The trigger receiving circuit 25 outputs a trigger signal and a sleep signal to the wheel-side controller 23 only when a signal that satisfies a predetermined reception condition is received. For this reason, both the power consumption by the signal output in the trigger receiving circuit 25 and the power consumption by the signal input in the wheel-side controller 23 can be reduced.

  (6) Moreover, the wheel side controller 23 can be controlled to a standby state. When a trigger signal or sleep signal that satisfies a predetermined reception condition is received in the trigger reception circuit 25, the trigger signal or sleep signal is input in the wheel-side controller 23, and the standby state is released. . For this reason, compared with the case where it is always in a normal state, the power consumption in the wheel side controller 23 can be reduced.

  (7) Further, since the wheel side unit 20 is operated by the electric power from the battery 28, the vehicle body side unit 30 that outputs the trigger signal is increased in size as the power consumption in the standby state in the wheel side unit 20 is reduced. High power can be suppressed.

  (8) By using the antenna group 32 in which the plurality of vehicle body side antennas 41 to 44 are combined, directivity in each direction can be provided (antenna gain G in each direction can be increased). For this reason, it is not necessary to provide a device (transmission circuit and antenna) for transmitting a trigger signal to each wheel 12, and the tire condition monitoring device 10 can be downsized. In addition, the number of parts can be reduced, and consequently the manufacturing cost can be reduced.

  (9) The vehicle body side unit 30 transmits a trigger signal when it detects that the ignition switch 14 is turned on. The trigger signal is a wake-up trigger signal that informs the wheel-side unit 20 that the ignition switch 14 is turned on. The position of the wheel 12 can be specified immediately after the ignition switch 14 is turned on, that is, immediately after the vehicle 11 is started.

  (10) Since the tire condition monitoring device 10 specifies the position of the wheel 12 by a trigger signal immediately after the ignition switch 14 is turned on, the tire condition monitoring device 10 can specify the position of the wheel 12 even when the vehicle 11 is not traveling. . When the position of the wheel 12 is specified using an ABS (anti-lock / brake system), the vehicle 11 must be traveling. However, if the ignition switch 14 is on even while the vehicle 11 is stopped, the position of the wheel 12 is specified. Yes. For this reason, the position of the wheel 12 can be specified even when it is desired to check the tire state before the vehicle 11 starts running, such as inspection before starting work.

  (11) When it is detected that the ignition switch 14 is turned off, the vehicle body unit 30 transmits a sleep signal. Since the wheel side unit 20 does not perform the data signal transmission operation when receiving the sleep signal, the power consumption of the battery 28 can be reduced.

In addition, you may change embodiment as follows.
As long as at least the power recovered by the power recovery circuit 29 is supplied to the trigger reception circuit 25, for example, the power recovered by the power recovery circuit 29 may be supplied to other than the trigger reception circuit 25. Further, for example, power from the battery 28 may be supplied to the trigger receiving circuit 25.

An ID code or the like may be included in the trigger signal, and it may be determined from the ID code whether a reception condition is satisfied.
The power recovery circuit 29 may include a full-wave rectifier circuit instead of a half-wave rectifier circuit. A filter may be provided before a signal is input to the rectifier circuit.

  The trigger signal may be output repeatedly when the ignition switch 14 is turned on, but the position of the wheel on which the wheel side unit 20 is provided cannot be specified, and can be output according to the user's operation. It may be. Moreover, these combinations may be sufficient.

  Even if it is not a trigger signal for specifying the position of the wheel on which the wheel-side unit 20 is provided, for example, it is a trigger signal that can set a reference value for the state of the tire (pressure in the tire or temperature in the tire). Also good.

  Even if no trigger signal or sleep signal is output from the vehicle body side unit 30, for example, the trigger signal or sleep signal may be output from a signal output device that outputs the trigger signal. A trigger signal or a sleep signal may be output from the terminal.

A receiving unit and a power recovery unit that can receive other signals may be used instead of the trigger signal or the sleep signal.
-The acceleration sensor 14 is used to detect the running and stop of the vehicle 11 when the ignition switch 14 is on, and the data signal may not be transmitted when the vehicle 11 is stopped. In this case, the power consumption of the battery 28 can be reduced.

-The sleep signal may not be transmitted.
A response signal may be transmitted from each wheel-side unit 20 when a trigger signal is transmitted toward one wheel-side unit 20. In this case, the wheel side unit 20 includes the reception intensity (reception power) in the response signal and transmits the response signal to the vehicle body side unit 30, so which wheel side unit 20 has the strongest reception intensity in the vehicle body side unit 30. I can grasp it. Then, it can be specified that the wheel side unit 20 having the strongest reception intensity is provided in the direction in which the trigger signal is transmitted with directivity.

  A data signal may be transmitted while the ignition switch 14 is off. In this case, the power consumption of the battery 28 can be increased by setting the first predetermined time interval for performing the tire condition measurement operation and the second predetermined time interval for performing the data signal transmission operation to be longer than when the ignition switch 14 is on. Can be reduced.

  -A communication frequency other than the 2.4 GHz band may be used. For example, from the viewpoint of miniaturization of the apparatus and securing of a communication distance, it is preferable to use a frequency of ultra high frequency or higher, and there is no problem even if other frequencies are used.

  In the embodiment, the antenna group 32 is configured by the first vehicle body side antenna 41 to the fourth vehicle body side antenna 44, but the number of vehicle body side antennas may be three, two, or five or more.

  In the embodiment, the first vehicle body side antenna 41 and the third vehicle body side antenna 43, and the second vehicle body side antenna 42 and the fourth vehicle body side antenna 44 are used as a set to generate a phase difference and the antenna group 32 has directivity. However, the vehicle body side antenna to be set may be appropriately changed.

-A two-wheel vehicle, a three-wheel vehicle, etc. may be sufficient and a vehicle more than five wheels may be sufficient.
-The wheel side unit 20 may be employ | adopted as a tire state monitoring apparatus, without including the vehicle body side unit 30. FIG.

Next, a technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) The antenna group is configured by feeding control for generating a phase difference between an antenna group in which a plurality of vehicle body side antennas for transmitting a trigger signal to the wheel side unit and the vehicle body side antennas in the plurality of wheels are generated. And a phase control circuit for generating a plurality of directivities in the group.

  (B) a transmission unit that transmits a state signal in a frequency band equal to or higher than an ultra-short wave indicating a state of the tire to the receiver, and the antenna receives the signal to the reception unit and transmits the state signal from the transmission unit. And a common antenna for both.

  DESCRIPTION OF SYMBOLS 10 ... Tire condition monitoring apparatus, 11 ... Vehicle, 12 ... Wheel, 16 ... Tire, 20 ... Wheel side unit, 23 ... Wheel side controller, 25 ... Trigger receiving circuit, 29 ... Power recovery circuit, 32 ... Antenna group, 33 ... Car body side controller 39... Phase control circuit, 41 to 44 Car body side antenna.

Claims (4)

A tire condition monitoring device for monitoring a condition in a tire, provided in a vehicle including a plurality of wheels with tires mounted on a wheel part,
An antenna for receiving signals;
A receiver capable of receiving a signal in a frequency band of ultra-high frequency or higher from the antenna;
A tire condition monitoring device comprising: a power recovery unit that recovers power from a signal received by the antenna and that can supply at least the recovered power to the reception unit. The receiving unit is controllable to a standby state and releases the standby state according to a trigger signal from a trigger transmission unit,
The tire condition monitoring device according to claim 1, wherein the power recovery unit recovers power from the trigger signal. A control unit that performs control for monitoring the state of the tire in response to reception of the signal;
The receiving unit determines whether or not a signal that satisfies a predetermined reception condition is received, and the control unit when the determination unit determines that a signal that satisfies the receiving condition is received Information indicating that the reception of the signal is output to the control unit, and when the determination unit determines that the signal that does not satisfy the reception condition is received, the control unit does not output the information indicating the reception of the signal. The tire condition monitoring device according to claim 1, further comprising a unit.   The tire state monitoring device according to claim 3, wherein the control unit is controllable to a standby state and releases the standby state according to information indicating reception from the reception unit.