Patent ID: 8937533
Filing Date: 2015-01-20
Classification: G06K,H04B

Abstract:
1. A contactless IC card reader configured to transmit signals composed of amplitude modulated carrier signals to a contactless IC card, comprising: a loop antenna; a contactless control means configured to modulate/demodulate signals transmitted to/received from the contactless IC card; and a main control means which is electrically connected to the contactless control means and administers the control of the entire card reader; wherein the contactless IC card reader is configured to communicate with the contactless IC card by means of an NRZ encoding method and by means of an ASK modulation method for which a modulation depth has an arbitrary value; wherein the modulation depth is varied by the contactless control means based on a predetermined command sent from the main control means, the modulation depth having multiple range widths with the arbitrary value as a standard, and wherein the range widths are in the range from 8% to 14% with the arbitrary value of 10% as the standard; wherein the contactless control means is configured to change the modulation depth by changing a register value associated with a circuit constant of a transmission output unit provided inside the contactless control means when the contactless control means receives the predetermined command to change the register value from the main control means; wherein the register value is first set to N as a default wherein the default register value, N, depends on the property of the loop antenna and leads to a modulation depth having the arbitrary value; and wherein the contactless control means is configured to change the register value from N to N+1, N+2, N−1, and N−2 in sequence.