| 摘要 |
PROBLEM TO BE SOLVED: To provide a road-vehicle optical communication device for a vehicle and a car navigation device which can enhance reliability for determining that the vehicle is in a communication area.SOLUTION: When a road-vehicle optical communication device 11 for a vehicle successively receives a downlink signal twice within a predetermined time, the device 11 determines that the vehicle is in a communication area and transmits an uplink signal. Thus, as the device can enhance reliability for determining that the vehicle is in a communication area, it is possible to prevent such inconvenience that the device transmits an unnecessary uplink signal. |
