AUTHENTICATION APPARATUS
The authentication apparatus disclosed here is formed of a unit to be controlled and a plurality of portable devices having communication with the unit via radio waves. The unit has a first controller, a first transmitter controlled by the first controller and a first receiver. Each of the portable devices has a second controller, a storage section that stores the replying order of the portable devices and is controlled by the second controller, a second transmitter and a second receiver. In response to communication signals sent from the first transmitter of the unit to each of the second receivers, each portable device replies with a first communication signal according to the replying order stored in the storage section. The first communication signal is sent back to the unit from each device with a predetermined time difference so as not to produce an overlapped period in the replying time.
1 . Authentication apparatus comprising:
a unit to be controlled; and
a plurality of portable devices communicating with the unit via radio waves, the unit to be controlled further including:
a first controller;
a first transmitter controlled by the first controller;
a first receiver, and
a storage section for storing the portable devices,
the plurality of portable devices, each of which further including:
a second controlled;
a storage section that stores a replying order of the portable devices and is controlled by the second controller;
a second transmitter; and
a second receiver,
wherein, in response to communication signals sent from the first transmitter of the unit to the second receiver, the portable devices send a first communication signal according to the replying order stored in the storage section, the first communication signal is sent back to the unit from each portable device with a predetermined time difference so as not to produce an overlapped period in replying time, when the first receiver of the unit receives the first communication signal having a predetermined data from a portable device in a communication with a predetermined time difference with the portable devices, the first controller of the unit stores the portable device in the storage section and carries out authentication with a firstly replied portable device.
2 . The authentication apparatus of claim 1 , wherein the first communication signal is successively sent back to the unit from each portable device with a predetermined time difference so as not to produce an overlapped period in replying time.
3 . The authentication apparatus of claim 1 , wherein numbers representing the replying order stored in the storage section of the portable devices do not take an identical number with one another but take sequential numbers, starting with a predetermined number.
4 . The authentication apparatus of claim 1 , wherein a maximum value of the numbers representing the replying orders stored in the storage section of the portable devices is determined to be equal to a maximum number of the portable devices the communicate with the unit.
5 . The authentication apparatus of claim 1 , wherein all the portable devices reply to the unit with the first communication signal formed of a predetermined same data.
6 . The authentication apparatus of claim 1 , wherein the portable devices do not have a uniform first communication signal; a portable device placed earlier in the replying order has a shorter form of the first communication signal.
7 . The authentication apparatus of claim 1 , wherein the first controller of the unit carries out authentication with a firstly replied portable device when the first communication signals are sent back with a predetermined time difference from the portable devices.
8 . The authentication apparatus of claim 1 , wherein the unit has a storage section for storing a portable device, when the first receiver of the unit receives the first communication signal having a receiving electric-field intensity within a predetermined range in a communication with a predetermined time difference with the portable devices, the first controller of the unit stores the device in the storage section and carries out authentication with a firstly replied portable device.
9 . (canceled)
10 . The authentication apparatus of claim 1 , wherein a time for waiting the first communication signal from the portable devices is changed according to the number of the portable devices that communicate with the unit.
11 . The authentication apparatus of claim 1 , wherein authentication of the portable devices is carried out with the use of a device-specific number that is given separately from the numbers representing the replying order of the devices.
12 . The authentication apparatus of claim 1 , wherein the first communication signal includes a plurality of parity bits in a device-specific number every predetermined bits, when the first receiver of the unit receives the first communication signal having complete agreement in parity every predetermined bits of the device-specific number in a communication with a predetermined time difference with the portable devices, the first controller of the unit stores the device in storage section and carries out authentication with a firstly replied portable device.
13 . The authentication apparatus of claim 1 , wherein the unit is employed for a locking system of a car.
14 . The authentication apparatus of claim 13 , wherein the first receiver controlled by the first controller effects door-locking/unlocking control with the use of a second communication signal sent from a portable device, the first communication signal contains a synchronizing signal different from a signal and data included in the second communication signal.
15 . The authentication apparatus of claim 14 , wherein the first communication signal has data that is different from a preamble signal included in the second communication signal.