Patent ID: 7852194

Claim:
A vehicle electronic key system having a vehicle-mounted device, and a portable device for receiving a request signal transmitted from the vehicle-mounted device and for transmitting an answer signal, the portable device comprising: a receiving circuit for receiving the request signal; a single receiving-sensitivity changing switch; a receiving-sensitivity indicator for indicating receiving sensitivity of the receiving circuit; and receiving-sensitivity changing control means for displaying receiving sensitivity of the receiving circuit on the receiving-sensitivity indicator, and for changing the receiving sensitivity of the receiving circuit on the basis of operation of the single receiving-sensitivity changing switch, wherein the receiving sensitivity of the receiving circuit is normally in a high sensitivity state, the high sensitivity state being a default state, wherein when the receiving sensitivity is the high sensitivity state, and the single receiving-sensitivity changing switch is operated for shorter than a predetermined period of time, the receiving sensitivity remains unchanged and the receiving-sensitivity indicator indicates the high receiving sensitivity by exhibiting a first color, whereas when the single receiving-sensitivity changing switch is operated for longer than the predetermined period of time the receiving sensitivity is changed to a sensitivity state that is lower than the high sensitivity state, thereby reducing an influence of signals from sources other than vehicle-mounted device, and the receiving-sensitivity indicator indicates the low receiving sensitivity by exhibiting a second color, and wherein when the receiving sensitivity is the low sensitivity state, and the single receiving-sensitivity changing switch is operated for shorter than the predetermined period of time, the receiving sensitivity remains unchanged and the receiving-sensitivity indicator indicates the low receiving sensitivity by exhibiting the second color, whereas when the receiving sensitivity of the receiving circuit is the lower sensitivity state, and the single receiving-sensitivity changing switch is operated for longer than the predetermined period of time, the receiving sensitivity is changed from the lower sensitivity state to the high sensitivity state, and the receiving-sensitivity indicator indicates the high receiving sensitivity by exhibiting the first color.