Tire air pressure monitoring system

Claim 2

The transmitter (3) according to claim 1, wherein the transmitter (3) has its own ID code, and the data wirelessly transmitted by the transmitting means (16) represents at least the pressure measured by the pressure sensor (11) and the ID code, and wherein the first commanding means (12, 13) performs the pseudorandom number calculation using the data representing the pressure measured by the pressure sensor (11) and the ID code.

Claim 3

The transmitter (3) according to claims 1 or 2, wherein the pseudorandom number calculation generates a random delay time, and the first commanding means (12, 13) adds the random delay time to a predetermined time period and sets the resultant sum as the measuring time interval.

Claim 5

The method according to claim 4, wherein the transmitter (3) has its own ID code, and the data wirelessly transmitted by the transmitter (3) represents at least the measured pressure and the ID code, and wherein the pseudorandom number calculation is performed using the data representing the measured pressure and the ID code.

Claim 6

A tire air pressure monitoring apparatus having a plurality of transmitters (3) for wirelessly transmitting data regarding the inner pressures of respective vehicle tires (2) and a receiver (4) for receiving the data wirelessly transmitted by the transmitters (3), wherein each transmitter (3) has its own ID code, and wherein the data transmitted from each transmitter (3) represents at least the measured pressure and the ID code, the apparatus being characterized by; a memory (22, 23) located in the receiver (4), wherein the memory (22, 23) includes a registration ID table for registering the ID codes of the transmitters (3) and reception count values, each reception count value (Cx) corresponding to one of the ID codes, wherein each reception count value (Cx) is used for judging whether the corresponding ID code registered in the registration ID table is valid; an initializing switch (27) connected to the receiver (4), wherein the initializing switch (27) is manipulated for initially registering the ID codes, which are contained in data received by the receiver (4), in the registration ID table; and a controller (20) located in the receiver (4), wherein, when a registration based on the manipulation of the initializing switch (27) is performed, the controller (20) sets each reception count value (Cx), which corresponds to one of the initially registered ID codes, to predetermined maximum count value.

Claim 7

The monitoring apparatus according to claim 6, wherein each transmitter (3) transmits data at predetermined time intervals, and wherein, when any of the ID codes, which have been registered in the registration ID table, is not received for a predetermined reference period, the controller (20) decrements the reception count value (Cx) corresponding to the unreceived ID code.

Claim 8

The monitoring apparatus according to claim 7, wherein, when any of the reception count values (Cx) reaches a predetermined minimum count value, the controller (20) judges that the corresponding ID code is invalid.

Claim 9

The monitoring apparatus according to claim 8, wherein the memory (22, 23) has a backup ID table for storing backup ID codes, and wherein the backup ID codes are different from the ID codes that have been registered in the registration ID table.

Claim 10

The monitoring apparatus according to claim 9, wherein the maximum number of backup ID codes stored in the backup ID table is predetermined, and, if an ID code that is not included in the registration ID table or in the backup ID table is received after the number of backup ID codes stored in the backup ID table reaches the predetermined maximum number, the backup ID code that was received earliest is deleted from the backup ID table.

Claim 11

The monitoring apparatus according to claims 9 or 10, wherein, when an ID code that is the same as one of the backup ID codes stored in the backup ID table has been received for a predetermined maximum number of times, the controller (20) judges that the backup ID code is valid.

Claim 12

The monitoring apparatus according to claim 11, wherein, when one of the reception count values (Cx) becomes less than or equal to the predetermined minimum count value and an ID code that matches one of the backup ID codes stored in the backup ID table has been received for the predetermined maximum number of times, the controller (20) deletes the ID code correspondinq to the reception count value (Cx) that is less than or equal to the minimum count value from the registration ID table and newly registers the backup ID code that has been received for the maximum number of times in the registration ID table.

Claim 13

The monitoring apparatus according to claim 12, wherein the controller (20) sets the reception count value (Cx) corresponding to the newly registered ID code to the maximum count value.

Claim 14

The monitoring apparatus according to claim 9, wherein, when an ID code corresponding to a reception count value (Cx) that is smaller than the maximum count value is received, the controller (20) increments the corresponding reception count value (Cx).

Claim 15

The monitoring apparatus according to claim 14, wherein, when the reception count values (Cx) corresponding to all the ID codes stored in the registration ID table have been incremented to the maximum count values, the controller (20) deletes all the backup ID codes from the backup ID table.