JP2003272060A - Tire state monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire state monitoring device for executing the stable transmission-reception regardless of an engine state (engine driving time, and engine stopping time). <P>SOLUTION: A transmitter 30 continuously transmits five times of a transmission cycle for alternately transmitting data at a bit rate of 20 [kbps] and a bit rate of 1 [kbps] in one time transmission operation regardless of a state of a vehicle 10. When an engine stops, a receiver 40 receives transmission data in intermittent operation. While, when the engine is driven, the receiver 40 receives the transmission data in ordinary operation (always, in an ON state). Thus, while restraining electric power consumption of a battery, the transmission data from the transmitter 30 is stably received by the receiver 40. Thus, the stable transmission-reception can be executed regardless of the engine state (engine driving time, and the engine stopping time). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire condition monitoring device, and more particularly to a wireless tire condition monitoring device capable of confirming a tire condition such as tire pressure from the passenger compartment.

[0002]

2. Description of the Related Art In recent years, a wireless tire condition monitoring device has been proposed in order to check the condition of a plurality of tires mounted on a vehicle in a passenger compartment. The monitoring device is composed of a plurality of transmitters mounted on the wheels of the tires and a receiver provided on the vehicle body of the vehicle. Each transmitter measures the state such as the air pressure and temperature of the corresponding tire, and wirelessly transmits the data indicating the measured state.
On the other hand, the receiver receives the data from the transmitter by the antenna and displays the state of each tire on an indicator provided in the driver's seat of the vehicle, for example.

In such a monitoring device, the transmitter mounted on the tire always indicates the tire condition at a constant bit rate regardless of the running condition of the vehicle, for example, whether the vehicle is running or the vehicle is stopped. A configuration for transmitting data has been proposed. On the other hand, when the engine is stopped, the receiver installed in the vehicle body does not constantly turn on the receiving circuit to turn on / off the receiving circuit in order to suppress battery power consumption. A configuration has been proposed in which reception is performed by so-called intermittent operation.

Generally, in a wireless tire condition monitoring device, since the positional relationship between the transmitter and the receiver is relatively changed due to the rotation of the tire, the voltage pattern induced in the receiving antenna by the radio wave from the transmitter. Changes according to the rotation angle of the tire as shown in FIG. This induced voltage pattern is determined by factors such as the vehicle, the tire position, the types of tires and wheels, the installation position of the receiving antenna, and the like. On the other hand, the induced voltage pattern has an induced voltage area (hereinafter referred to as a null point) that is lower than the receiving sensitivity of the receiver.

Since there are null points in this way,
The transmission data from the transmitter can be normally received only in the receivable area other than the null point. Also,
As the tire rotation speed increases with the vehicle speed, the time in the receivable area also becomes shorter.Therefore, the higher the tire rotation speed, the more difficult it is for the receiver to receive the transmission data from the transmitter. Becomes Furthermore, the receiver cannot receive the transmission data from the transmitter in the speed range in which the time of the receivable area is shorter than the transmission time.

In order to solve such a problem, for example, a method of increasing the output of the transmitter so that a null point does not occur can be considered. However, the transmitter cannot increase the transmission output beyond the output specified by the Radio Law.
Also, the transmission output cannot be increased from the viewpoint of the life of the battery that is the power source of the transmitter. Therefore, it is impossible to adopt a method of increasing the output of the transmitter to prevent the null point from occurring.

Next, a method of optimizing the installation position of the receiving antenna of the receiver so that a null point does not occur can be considered. In this case, the induced voltage pattern of the receiving antenna varies depending on factors such as the type of the vehicle, the tire, and the tire and the wheel, so a huge evaluation must be performed in order to optimize the installation position of the receiving antenna.
Not realistic. Further, the installation position of the receiving antenna of the receiver may not be set at an optimum position due to vehicle restrictions, and there is also a demand to increase the degree of freedom in the installation position of the receiving antenna. Therefore, it is not possible to adopt a method of optimizing the installation position of the receiving antenna to prevent a null point from occurring.

Next, consider a method of shortening the transmission time of the transmitter to cope with transmission / reception in a high speed region. In order to shorten the transmission time, there are a method of reducing the number of data bits (data length) and a method of increasing the bit rate. However, since the number of bits of data is already the minimum required number of bits, a method of reducing the number of bits cannot be adopted. On the other hand, the method of increasing the bit rate is such that even when a null point occurs in the voltage pattern induced in the receiving antenna, the time of the receivable area in the traveling speed region of the vehicle is
Stable transmission / reception can be realized by selecting a bit rate such that the transmission time is sufficiently short and combining methods such as transmitting data several times in one transmission.

[0009]

However, when the engine is stopped, the receiver is operated intermittently in order to suppress the power consumption of the battery. For this reason, when transmitting the transmission data at a high bit rate in a short time when the engine is stopped, the OFF state time in the intermittent operation must be shortened.
Unless the N state time is lengthened, the transmitted data cannot be stably received. On the other hand, in order to suppress the power consumption of the battery when the engine is stopped, it is necessary to shorten the ON time in the intermittent operation.
Therefore, it has been difficult to satisfy such conflicting problems.

The present invention has been made in view of these problems, and its purpose is to perform stable transmission / reception regardless of the state of the engine (when the engine is operating or when the engine is stopped). It is to provide a tire condition monitoring device capable of performing the above.

[0011]

In order to achieve the above-mentioned object, in the invention described in claim 1, a transmitting means which is provided on a tire of a vehicle and wirelessly transmits data indicating the condition of the tire, and the transmitting means. A tire condition monitoring device comprising: a receiving means for receiving the data transmitted from the means by a receiving antenna provided in the vehicle and processing the received data, wherein the transmitting means includes a plurality of transmitting means in one transmitting operation. Send data at different bit rates.

According to a second aspect of the present invention, in the tire condition monitoring apparatus according to the first aspect, the transmitting means can receive by the receiving means when the speed of the vehicle is less than a predetermined speed in one transmission operation. Data is transmitted at a bit rate and a bit rate that can be received by the receiving means when the vehicle speed is equal to or higher than a predetermined speed.

According to a third aspect of the present invention, in the tire condition monitoring apparatus according to the first or second aspect, the transmitting means has a registration mode for registering its own identification information in the receiving means, and a normal mode. Sends data at different bit rate combinations.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which a tire condition monitoring device according to the present invention is embodied in a vehicle such as an automobile will be described below with reference to the drawings.

As shown in FIG. 1, a tire condition monitoring device 1
Includes four transmitters 30 provided on the four tires 20 of the vehicle 10 and one receiver 40 provided on the vehicle body 11 of the vehicle 10.

Each transmitter 30 is fixed inside the corresponding tire 20, for example, a wheel 21 of the tire 20. Then, each transmitter 30 has a corresponding tire 2
The state of 0, that is, the air pressure in the corresponding tire 20 is measured, and data including the air pressure data of the tire 20 obtained by the measurement is wirelessly transmitted at predetermined time intervals.

The receiver 40 is installed at a predetermined location on the vehicle body 11 and operates by electric power from a battery (not shown) of the vehicle 10, for example. The receiver 40 includes one receiving antenna 41 and is connected to the receiver 40 via a cable 42. The cable 42 is preferably a coaxial cable that is not significantly affected by noise. The receiver 40 receives the data transmitted from each transmitter 30 via the receiving antenna 41. Specifically, when data is transmitted from each transmitter 30 by radio waves, the receiving antenna 41 induces a voltage according to the electric field strength of the received radio wave, and the induced voltage signal is received by the receiver 40. Output to.

The display device 50 is arranged in a visual range of a driver of the vehicle 10 such as a passenger compartment. The display 50 is connected to the receiver 40 via a cable 43. As shown in FIG. 2, each transmitter 30 includes a transmission controller 31 including a microcomputer or the like. The transmission controller 31 includes, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (R).
AM). A unique ID is previously stored as identification information in the internal memory of the transmission controller 31, for example, ROM.
The code is registered. And this ID code is
It is used to identify the four transmitters 30 provided on the four tires 20.

The pressure sensor 32 measures the air pressure in the tire 20, and outputs the air pressure data obtained by the measurement to the transmission controller 31. The temperature sensor 33 is
The temperature inside the tire 20 is measured, and the temperature data obtained by the measurement is output to the transmission controller 31.

The transmission controller 31 receives the input air pressure data and temperature data and the I registered in itself.
The D code is output to the transmission circuit 34. The transmission circuit 34 is
The transmission data including the air pressure data, the temperature data, and the ID code is wirelessly transmitted to the receiver 40 via the transmission antenna 35.

The detection circuit 36 detects a signal received via the transmission antenna 35. Then, the transmitting antenna 35
When a trigger signal from the external control device 60 described later is detected, the fact is output to the transmission controller 31. The transmitter 30 includes a battery 37. The transmitter 30 operates by the electric power from the battery 37.

As shown in FIG. 3, the receiver 40 includes a reception controller 44 and a reception circuit 45 for processing the data received via the reception antenna 41.
Reception controller 44 including a microcomputer or the like
Includes a CPU, a ROM and a RAM, for example. The reception circuit 45 receives the transmission data from each transmitter 30 via the reception antenna 41. In addition, the receiving circuit 45,
After demodulating and decoding the reception data, the reception controller 4
Send to 4.

The reception controller 44 grasps the air pressure of the tire 20 corresponding to the transmitter 30 of the transmission source based on the reception data. Further, the reception controller 44 causes the display 50 to display data regarding the air pressure. In particular, when the air pressure of the tire 20 is abnormal, a warning to that effect is displayed on the display 50.

Next, in the case where the voltage pattern induced in the receiving antenna 41 by the radio wave from the transmitter 30 of the transmission source has the characteristic as shown in FIG. Considering a case where the tire 20 is mounted and the vehicle travels at a speed of 300 [km / h], the time required for the tire 20 to make one rotation is about 24.6 [msec]. However, as shown in FIG. 4, the receivable time of the areas A and B during one rotation of the tire 20 is 11.2 [msec] and 12.3 [msec], respectively, and the total of them is 23. It is 0.5 [msec]. Therefore, under this condition, the transmission data of 40 [bit] is set to 1
When transmitting at a bit rate of [kbps], the time required for one data transmission is 40 [msec]. As a result, the time (11.
2 [msec] and 12.3 [msec]) are shorter than the time required for data transmission (40 [msec]). Therefore, no matter which timing the transmission data is transmitted, the reception antenna 41 cannot completely receive the transmission data due to the presence of the null point.

On the other hand, when transmitting the same transmission data of 40 [bits] at a bit rate of 20 [kbps],
The time required for one data transmission is 2 [msec]. In this case, depending on the transmission timing, reception may not be possible due to the influence of the null point. However, the time required for data transmission of 2 [msec] is equal to the above 11.2.
In some cases, the data can be received because it is stored in the receivable areas A and B of [msec] and 12.3 [msec]. Moreover, by continuously transmitting the same data a plurality of times, it is possible to improve the possibility that the transmission data can be normally received by the reception antenna 41 without being affected by the null point.

Next, "time required for one rotation of the tire 20", "time in receivable area A", "time in receivable area B", "1 [kbp] corresponding to the speed of the vehicle 10"
5] "Receivability at 20 seconds" and "Receivability at 20 [kbps]" are shown in FIG. As shown in FIG.
When the speed is less than 80 [km / h] per hour and the bit rate is 1 [kbps], the receiver 40 can receive the transmission data. However, the vehicle 10
When the speed is 100 [km / h] or more,
When the bit rate is 1 [kbps], the receiver 40
Cannot receive transmitted data.

On the other hand, the speed of the vehicle 10 is 40 [km / h
h] or more and the bit rate is 20 [kbp
[s], the receiver 40 can receive the transmission data. However, as described in the problem to be solved by the invention, since the receiver 40 is intermittently operated when the engine is stopped, it is difficult to receive at a bit rate of 20 [kbps].

Next, the intermittent operation of the receiving circuit 45 in the receiver 40 when the engine mounted on the vehicle 10 is stopped will be described. In addition, whether or not the engine is stopped is determined based on an ignition signal from a key switch of the vehicle 10. That is, when it is determined that the engine is stopped based on the ignition signal, the receiving circuit 45 of the receiver 40 performs the intermittent operation. On the other hand, when it is determined that the engine is operating, the receiving circuit 45 of the receiver 40 performs a normal operation (always ON state). Further, when the engine is stopped, the reception circuit 45 of the receiver 40 receives the transmission data from each transmitter 30 in the intermittent operation pattern as shown in FIG.

As described above, the transmitter 30 continuously transmits the same transmission data a plurality of times in one transmission operation in order to avoid the influence of the null point. On the other hand, the receiver 40
Receives a part of the transmission data from the transmitter 30 while the receiving circuit 45 is in the ON state for 20 [msec]. When it is determined that the data is the transmission data from the transmitter 30, the receiving circuit 45 is turned on until the reception of the plurality of continuous transmission data sets transmitted from the transmitter 30 is completed. maintain.

Here, whether or not the receiver 40 is transmission data is determined as follows. That is, when an 8-bit header (for example, a header in which “0 (zero)” is 8-bit continuous) is received after continuously receiving pulses of a predetermined width, it is determined that the data is transmission data.

On the other hand, in the receiver 40, the receiving circuit 45 has 20
When the transmission data from the transmitter 30 is not received during the ON state of [msec], the receiving circuit 45 is set to 80
It is turned off for [msec].

If it is assumed that transmission data of 40 [bits] is transmitted 6 times continuously at a bit rate of 1 [kbps], the time required for a series of transmissions is 240 [ms].
ec]. As shown in FIG. 6, when the ON state of the intermittent operation pattern of the receiving circuit 45 is 20 [msec] and the OFF state is 80 [msec], 240 [msec].
>> 20 [msec] is established. Therefore, 2
240 [msec] during ON state of 0 [msec]
It is very likely that you will receive a portion of the transmitted data. As a result, during the ON state of 20 [msec], 240
When a part of the transmission data of [msec] is received,
The receiving circuit 45 maintains the ON state until receiving the transmission data. Therefore, even if the receiver 40 operates intermittently,
The transmission data from the transmitter 30 can be reliably received.

On the other hand, if the transmission data is similarly transmitted at a bit rate of 20 [kbps], the time required for a series of transmission is 12 [msec]. Figure 6
As shown in, the intermittent operation pattern of the receiving circuit 45 is turned on.
The state is 20 [msec] and the OFF state is 80 [mse].
c], so 12 [msec] <20 [msec]
The relationship is established. Therefore, ON for 20 [msec]
During the state, it is unlikely to receive a part of the transmission data of 12 [msec]. As a result, O of 20 [msec]
In the N state, it is often impossible to receive a part of the transmission data of 12 [msec].

Therefore, if the ON / OFF ratio of the intermittent operation pattern of the receiving circuit 45 is not changed and the intermittent operation pattern is simply increased in speed, it is possible to cope with a high bit rate. However, in reality, the receiving circuit 4
5 ON state rise time (several [msec] to 10
(About [msec]), there is a limit to speeding up the intermittent operation pattern. As a result, in reality, a method of lengthening the ON state time in the intermittent operation pattern of the receiving circuit 45 has to be adopted, but when the ON state time is lengthened, it is mounted on the vehicle 10. It becomes difficult to suppress the power consumption of the battery. Therefore, when the engine is stopped, it is optimal for the transmitter 30 to continuously transmit the transmission data of 40 [bits] at a bit rate of 1 [kbps] a plurality of times.

Therefore, a vehicle speed sensor for detecting the state of the vehicle 10 (running state, stopped state) is provided in the transmitter 30, and the transmission data is transmitted at an optimum bit rate according to the state of the vehicle 10. Can also be considered. However, in such a configuration, the vehicle speed sensor becomes an essential component of the transmitter 30. In addition, considering that the state of the vehicle 10 must be reliably detected and that the transmitter 30 is mounted inside the tire 20, the reliability can be improved even under the environment in which the tire 20 is repeatedly violently vibrated. It is necessary to select a vehicle speed sensor that has However, it is difficult to install the vehicle speed sensor in the transmitter 30 after selecting such a reliable vehicle speed sensor.

Therefore, in the present embodiment, the transmitter 30 does not have a vehicle speed sensor, and transmission data in which different bit rates are mixed is transmitted from the transmitter 30. That is, as shown in FIG.
Irrespective of the state of the vehicle 10, the transmission cycle in which transmission data is alternately transmitted at a bit rate of 20 [kbps] and a bit rate of 1 [kbps] in one transmission operation is continuously transmitted five times. .

Here, in the case where the transmission cycle of transmitting the transmission data alternately at the bit rate of 20 [kbps] and the bit rate of 1 [kbps] is transmitted five times in succession, the data is transmitted once. This time is 210 [mse
c] (= 2 [msec] × 5 + 40 [msec] × 5)
Becomes Therefore, as shown in FIG. 6, the ON state of the intermittent operation pattern of the receiving circuit 45 is 20 [msec], OF
When the F state is 80 [msec], 210 [mse]
The relationship of c] >> 20 [msec] is established. Therefore, while the ON state is 20 [msec], 210 [ms]
ec] is very likely to be received. As a result, during the ON state of 20 [msec], 2
When a part of the transmission data of 10 [msec] is received, the reception circuit 45 outputs O until the transmission data is completely received.
Maintain N state. Therefore, even if the receiver 40 operates intermittently, it is possible to reliably receive the transmission data from the transmitter 30.

Therefore, if such a transmission cycle is continuously transmitted five times, the receiver 40 can receive the transmission data at any bit rate regardless of the state of the vehicle 10. That is, the speed of the vehicle 10 is 80
In the case of [km / h] or less, the transmission data is 1 [kbp
The receiver 40 can receive the transmission data at the bit rate of [s]. On the other hand, the speed of the vehicle 10 is 4 per hour.
When it is 0 [km / h] or more, the transmission data is 20 [kb
When the bit rate is ps], the receiver 40 can receive the transmission data. Of course, the speed of the vehicle 10 is 40 [km / h] or more per hour and 80 [km / h] per hour.
In the following cases, the receiver 40 can receive the transmission data at any bit rate. As a result, the receiver 40 can reliably receive the transmission data from the transmitter 30 regardless of the state of the vehicle 10 without providing the vehicle speed sensor in the transmitter 30. In addition,
As shown in FIG. 7B, the transmission cycle is the reverse of the transmission cycle shown in FIG. 7A, that is, a transmission cycle in which the bit rate of 1 [kbps] and the bit rate of 20 [kbps] are exchanged. May be.

Next, the external control device 60 which transmits a trigger signal for temporarily setting the transmitter 30 to the registration mode.
Will be described with reference to FIG. As shown in FIG. 8, the external control device 60 includes a switch 61 for temporarily setting the transmitter 30 in the registration mode. Oscillation circuit 6
2 generates an oscillation signal for setting the registration mode based on the operation of the switch 61. The transmission circuit 63 modulates the oscillation signal generated by the oscillation circuit 62 and transmits a trigger signal via the transmission antenna 64. External control device 6
0 operates by the electric power from the battery 65. The external control device 60 is preferably a portable device.

Next, the operation of storing the ID code of the transmitter 30 in the receiver 40 after shifting the transmitter 30 to the registration mode by using the external control device 60 will be described.

When the switch 61 of the external control device 60 is operated in the vicinity of the transmitter 30 mounted on one of the tires 20 of the vehicle 10, the transmission antenna 64 of the external control device 60 shifts to the registration mode. The trigger signal of is transmitted. Then, the trigger signal is transmitted to the transmitter 30.
The transmission controller 3 detects that the trigger signal for shifting to the registration mode is detected by the detection circuit 36 of FIG.
It is output to 1. As a result, transmission data including the ID data registered in the ROM is transmitted from the transmitter 30 via the transmission antenna 35. At this time, as shown in FIG. 9, after transmitting the transmission data of 1 [kbps] twice,
The transmission cycle of transmitting the transmission data of 0 [kbps] twice is repeated a predetermined number of times (for example, twice). as a result,
Based on this transmission cycle, the receiver 40 determines that the transmitter 3
It is determined that the registration mode is a mode in which the ID code registered in 0 is registered in the receiver 40. As a result of the determination, the reception controller 44 of the receiver 40 stores the ID code included in the transmission data in the RAM of the reception controller 44. When the transmission in the registration mode is completed, the transmitter 3
0 shifts to the normal mode and performs the transmission operation at every predetermined time.

Therefore, when such a registration operation is executed for all the tires 20, the receiver 40 is set to the vehicle 10.
The ID code of the transmitter 30 mounted on the four tires 20 can be stored.

As described above in detail, according to this embodiment, the following actions and effects can be obtained. (1) Regardless of the state of the vehicle 10, the transmitter 30 has five transmission cycles in which transmission data is alternately transmitted at a bit rate of 20 [kbps] and a bit rate of 1 [kbps] in one transmission operation. It transmits continuously. When the engine is stopped, the receiver 40
Receives transmission data in an intermittent operation. On the other hand, when the engine is driven, the receiver 40 receives the transmission data in the normal operation (always ON state). Therefore, while suppressing the power consumption of the battery, the transmitter 30
The transmission data from is stably received by the receiver 40.
Therefore, stable transmission / reception can be performed regardless of the state of the engine (when the engine is driven or when the engine is stopped).

(2) In addition, regardless of the state of the vehicle 10, the transmitter 30 is 20 [kbp in one transmission operation.
The transmission cycle in which the transmission data is alternately transmitted at the bit rate of [s] and the bit rate of 1 [kbps] is continuously transmitted five times. Therefore, the receiver 40 can receive the transmission data at any bit rate regardless of the state of the vehicle 10. That is, when the speed of the vehicle 10 is 80 [km / h] or less, the transmission data is 1
When the bit rate is [kbps], the receiver 40 can receive the transmission data. On the other hand, when the speed of the vehicle 10 is 40 [km / h] or more, the transmission data is 2
The receiver 40 can receive the transmission data when the bit rate is 0 [kbps]. As a result, the transmission data from the transmitter 30 is received by the receiver 4 regardless of the state of the vehicle 10 without providing a vehicle speed sensor in the transmitter 30.
0 can be reliably received. Therefore, the tire condition monitoring device 1 determines the condition of the vehicle 10 (running condition, stopped condition).
Regardless of this, stable transmission / reception can be performed.

(3) In the receiver 40, the receiving circuit 45 is ON
While in the state, it receives some of the transmitted data from transmitter 30. When it is determined that the data is the transmission data from the transmitter 30, the receiving circuit 45 is turned on until the reception of the plurality of continuous transmission data sets transmitted from the transmitter 30 is completed. I am maintaining. Therefore, when the receiver 40 determines that part of the transmission data from the transmitter 30 is received, the transmission data is reliably received. Therefore, the receiver 40 can stably receive the transmission data.

(4) In the vicinity of the transmitter 30 mounted on one of the tires 20 of the vehicle 10, the external control device 6
When the switch 61 of 0 is operated, 1 [kbp
[s] transmission data is transmitted twice, then 20 [kbps]
The transmission cycle of transmitting the transmission data of 2 times is repeated a predetermined number of times (for example, twice). That is, in the registration mode, the transmission data is transmitted at a bit rate combination different from that in the normal mode. as a result,
Based on this transmission cycle, the receiver 40 determines that the transmitter 3
It is determined that the registration mode is a mode in which the ID code registered in 0 is registered in the receiver 40, and the ID code is stored in the RAM of the reception controller 44. Therefore, the receiver 40
The ID code of the transmitter 30 is received by the receiving controller 44 without providing a registration mode switch or the like or adding a flag or the like to the transmission data for shifting to the registration mode.
Can be registered in the RAM.

The above embodiment can be modified and embodied as follows. The configuration in which the transmission cycle of transmitting the transmission data alternately at the bit rate of 20 [kbps] and the bit rate of 1 [kbps] is continuously performed five times in one transmission operation is limited to five times. It is not limited to this, and may be changed as appropriate.

The combination of bit rates in one transmission operation may be changed as appropriate. -A configuration may be used in which three or more bit rates are mixed and transmitted.

A receiver 40 having one transmitter 30 and a receiving antenna 41 corresponding to the transmitter 30, that is, the tire condition monitoring device 1 in which the transmitter 30 and the receiving antenna 41 are one-to-one. The above embodiment may be applied.

When the air pressure of the tire 20 is abnormal, an alarm may be provided to give a sound to that effect. In addition, the speaker installed in the vehicle 10 in advance may be used as the alarm device.

The air pressure data transmitted from the transmitter 30 may be data specifically indicating the value of the air pressure or simply data indicating whether or not the air pressure is within the allowable range.

The vehicle is not limited to a four-wheel vehicle, but two vehicles
The embodiment may be applied to a wheeled bicycle or motorcycle, a multi-wheeled bus or a towed vehicle, an industrial vehicle equipped with the tires 20 (for example, a forklift), or the like. In addition, when applying the said embodiment to a towed vehicle, it goes without saying that the receiver 40 and the display 50 are installed in the towed vehicle.

Further, the technical idea grasped from the above embodiment will be described below together with their effects. [1] In the tire condition monitoring device according to claim 1,
The transmitting means is a tire condition monitoring device for continuously transmitting a predetermined number of transmission cycles for sequentially transmitting data at a plurality of different bit rates in one transmission operation. According to this structure, since the receiving means can receive the transmission data at any bit rate, stable transmission / reception can be performed regardless of the state of the engine (when the engine is driven or when the engine is stopped). You can

[2] In the tire condition monitoring device according to the third aspect, the transmitting means has a bit rate different from that in the normal mode after shifting from the normal mode to the registration mode based on a trigger signal from the outside. A tire condition monitoring device that transmits data in combination, and the receiving means registers the identification information included in the received data. With this configuration,
The identification information in the transmitting means can be registered in the receiving means without providing the receiving means with a switch for the registration mode or adding a flag or the like to the transmission data for shifting to the registration mode.

In the present specification, "measurement and transmission at predetermined time intervals" and "regular measurement and transmission" mean that the measurement time interval and the transmission time interval are completely constant. is not. That is, a slight variation in the measurement time interval and the transmission time interval is also included in the category of the above wording.

[0056]

Since the present invention is constructed as described above, it has the following effects. According to the invention described in claim 1 or claim 2, stable transmission / reception can be performed regardless of the state of the engine (when the engine is driven or when the engine is stopped).

According to the third aspect of the invention, the receiving means can determine that the mode is the registration mode. Therefore, based on this judgment, the identification information in the transmitting means can be registered in the receiving means.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tire condition monitoring device.

FIG. 2 is a block diagram showing a transmitter.

FIG. 3 is a block diagram showing a receiver.

FIG. 4 is an explanatory diagram showing a voltage pattern induced in a receiving antenna when the tire makes one rotation.

FIG. 5 is an explanatory diagram showing a relationship between vehicle speed and receivability.

FIG. 6 is an explanatory diagram showing an intermittent operation pattern in the receiving circuit.

FIG. 7 is an explanatory diagram showing transmission data in which different bit rates are mixed.

FIG. 8 is a block configuration diagram showing an external control device.

FIG. 9 is an explanatory diagram showing a bit rate of transmission data in a registration mode.

[Explanation of symbols]

1 ... Tire condition monitoring device, 10 ... Vehicle, 20 ... Tire,
30 ... Transmitter as transmitting means, 40 ... Receiver as receiving means, 41 ... Receiving antenna.

Claims (3)

[Claims] 1. A transmission means provided on a tire of a vehicle for wirelessly transmitting data indicating a tire condition, and a reception antenna provided on the vehicle to receive the data transmitted from the transmission means, and receive the received data. A tire condition monitoring device comprising: a receiving means for processing, wherein the transmitting means transmits data at a plurality of different bit rates in one transmission operation. 2. The tire condition monitoring apparatus according to claim 1, wherein the transmitting means includes a bit rate receivable by the receiving means when the vehicle speed is less than a predetermined speed in one transmission operation, and the vehicle speed. A tire condition monitoring device that transmits data at a bit rate that can be received by the receiving unit when the speed is equal to or higher than a predetermined speed. 3. The tire condition monitoring device according to claim 1 or 2, wherein the transmitting means uses a combination of bit rates different from those in the normal mode in a registration mode in which the identification information of the transmitting means is registered in the receiving means. A tire condition monitoring device that transmits data.