Tire air pressure warning system and method for warning against tire air pressure

1. A system for warning against a tire air pressure comprising:

air pressure measuring means for measuring a tire air pressure of a tire of a vehicle;

air pressure judging means for judging, on the basis of the tire air pressure measured by said air pressure measuring means, whether or not the tire air pressure is proper;

warning issuing means for issuing, if a result of the judgment by said air pressure judging means is negative, a warning;

driver on-board judging means for judging whether or not a driver is on board the vehicle; and

driver detecting means for detecting whether or not the driver is in the proximity to the vehicle,

if the result of the judgment by said air pressure judging means is negative, a result of the judgment by said driver on-board judging means is negative and a result of the detection by said driver detecting means is positive, said warning issuing means issues the warning outside the vehicle.

2. A system for warning against a tire air pressure according to claim 1 , wherein, if the result of the judgment by said air pressure judging means is negative and the result of the judgment by said driver on-board judging means is positive, said warning issuing means issues the warning inside the vehicle.

3. A system for warning against a tire air pressure according to claim 1 , wherein said driver on-board judging means judges that the driver is not on board the vehicle when a switch for traveling of the vehicle is off and judges that the driver is on board the vehicle when the switch for traveling is on.

4. A system for warning against a tire air pressure according to claim 1 , wherein

said air pressure measuring means is provided for each tire or a wheel that supports each tire;

said air pressure judging means is arranged on a bodywork portion of the vehicle; and

said air pressure measuring means transmits a radio signal to said air pressure judging means to notify the tire air pressure that has been measured.

5. A system for warning against a tire air pressure according to claim 1 , wherein said driver detecting means detects proximity of the driver to the vehicle upon receipt of a radio signal issued by the driver.

6. A system for warning against a tire air pressure according to claim 5 , wherein

said air pressure judging means includes air pressure receiving means for receiving the radio signal transmitted by said air pressure measuring means; and

common receiving means is shared by said air pressure receiving means and receiving means for receiving, in said driver detecting means, the radio signal issued by the driver.

7. A system for warning against a tire air pressure according to claim 5 , wherein

the vehicle includes a keyless entry system; and

said driver detecting means detects the proximity of the driver to the vehicle on the basis of an unlock signal used for the keyless entry system.

8. A system for warning against a tire air pressure according to claim 7 , wherein:

if the result of the judgment by said air pressure judging means is negative, a result of the judgment by said driver on-board judging means is negative and a result of the detection by said driver detecting means is positive on the basis of the unlock signal, said warning issuing means issues the warning outside the vehicle and forbids the keyless entry system to unlock doors of the vehicle on the basis of the unlock signal; and

upon completion of the issuing of the warning, said warning issuing means releases the forbidding.

9. A system for warning against a tire air pressure according to claim 7 , wherein:

the warning issued by said warning issuing means and a normal answerback to the unlock signal for the keyless entry system are issued by common warning means; and

the warning issued by said warning issuing means is different in manner from the normal answerback to the unlock signal.

10. A system for warning against a tire air pressure according to claim 1 , wherein said air pressure measuring means measures the tire air pressure at first intervals while the vehicle is traveling and measures the tire air pressure at second intervals longer than the first intervals while the vehicle is parked.

11. A method for warning against a tire air pressure comprising the steps of:

(a) measuring a tire air pressure of a tire of a vehicle;

(b) judging, on the basis of the tire air pressure measured in said step (a) of measuring, whether or not the tire air pressure is proper;

(c) judging whether or not a driver is on board the vehicle;

(d) detecting whether or not the driver is in the proximity to the vehicle; and

(e) if a result of said step (b) of judging is negative, issuing a warning in accordance with results of said step (c) of judging and said step (d) of detecting,

wherein, if the result of said step (b) of judging is negative, the result of said step (c) of judging is negative and the result of said step (d) of detecting is positive, a warning is issued outside the vehicle in said step (e) of issuing.

12. A method for warning against a tire air pressure according to claim 11 , wherein, if the result of said step (b) of judging is negative and the result of said step (c) of judging is positive, the warning is issued inside the vehicle in said step (e) of issuing.

13. A method for warning against a tire air pressure according to claim 11 , wherein said step (c) of judging judges that the driver is not on board the vehicle when a switch for traveling of the vehicle is off and judges that the driver is on board the vehicle when the switch is on.

14. A method for warning against a tire air pressure according to claim 11 , further comprising the steps of:

issuing a radio signal including the tire air pressure that has been measured in said step (a) of measuring; and

receiving the radio signal.

15. A method for warning against a tire air pressure according to claim 11 , wherein, in said (d) of detecting, proximity of the driver is detected by receipt of a radio signal issued by the driver.

16. A method for warning against a tire air pressure according to claim 15 , wherein:

the vehicle includes a keyless entry system; and

the proximity of the driver is detected on the basis of an unlock signal used for the keyless entry system in said step (d) of detecting.

17. A method for warning against a tire air pressure according to claim 16 , wherein said step (e) of issuing comprises the sub-steps of:

(e-1) if the result of said step (b) of judging is negative, the result of (c) of judging is negative and the result of (d) of detecting is positive on the basis of the unlock signal, issuing the warning outside the vehicle;

(e-2) forbidding the keyless entry system to unlock doors of the vehicle on the basis of the unlock signal; and

(e-3) upon completion of said sub-step (e-1) of issuing, releasing the forbidding of said sub-step (e-2).

18. A method for warning against a tire air pressure according to claim 16 , wherein:

the warning issued in said step (e) of issuing and a normal answerback to the unlock signal for the keyless entry system are issued in common warning means; and

the warning issued in said step (e) of issuing is different in manner from the normal answerback to the unlock signal.

19. A method for warning against a tire air pressure according to claim 11 , wherein, in said step (a) of measuring, the tire air pressure is measured at first intervals while the vehicle is traveling and is measured at second intervals longer than the first intervals while the vehicle is parked.