| 摘要 |
PROBLEM TO BE SOLVED: To actualize the reader writer at a low price by generating a power and signal transmit signal for a noncontact IC card which uses phase-modulated sine waves of two layers. SOLUTION: A control circuit 501 generates digital clock signals CKϕ1 and CKϕ2 which are 90 deg. out of phase with each other, sine wave switching circuits 502 and 503 generate sine wave signals, and inverting circuits 504 and 505 invert their outputs to generate sine wave signals of four phases in total, i.e., sine wave signals sinϕ1 and sinϕ2 of the clock signals CKϕ1 and CKϕ2 and their inverted signals- sin ϕ1 and- sin ϕ2; and an analog multiplexer 506 for modulation switches the sinϕ1 and- sin ϕ2, and sin ϕ2 and- sinϕ1 according to a transfer data signal DATA to perform phase modulation, thereby obtaining driving signals for two independent coils which performs data transfer by using power transmission and phase modulation between the reader writer and card through buffer amplifiers 507 and 508. |
