Patent ID: 6489883
Filing Date: 2002-12-03
Classification: B60R,G06K,G07C

Abstract:
A non-contact data carrier comprising:carrier signal detection means for detecting a carrier signal transmitted from a question unit, for comparing an amplitude level of said carrier signal with a predetermined reference level and for placing said non-contact data carrier into a sleep state on the basis of the comparison result; a main circuit unit comprising a memory for holding data, a demodulation circuit, a modulation circuit and a control circuit; switching means for switching output condition of power supplied from an internal battery to said main circuit unit; electric-supply means for rectifying said carrier signal and generating a voltage; and electric-supply switching means to which an output of said electric-supply means and an output of said switching means are input, said electric-supply switching means outputting a voltage to said main circuit unit, wherein said carrier signal detection means compares the amplitude level of said carrier signal and the predetermined reference level, and when said level of said carrier signal is higher than said reference level, said switching means goes into an â€œONâ€  state so that power of said battery is supplied to said electric-supply switching means, and when said switching means is in the â€œONâ€  state, a voltage value of said battery and a value of said voltage generated by said electric-supply means are compared, and when said voltage value of said battery is higher than said voltage generated by said electric-supply means, said electric-supply switching means outputs power of said battery to said main circuit unit.