| 摘要 |
<p>PURPOSE:To prevent a decrease in read precision due to interaction of radio waves generated between respective reading devices by radiating question signals by all the reading devices at the same time. CONSTITUTION:Respective radio card readers 2a and 2b read information in identification codes, etc., from radio cards 1a and 1b. Respective controllers 11a and 11b receive information from the radio card readers 2a and 2b and collates it with previously registered information to control an electric lock 12 or automatic door 13 according to the result. A controller 14 send a standardized time signal successively to the controllers 11a and 11b at the same time. The controllers 11a and 11b continue to send the reference time signal to the respective radio card readers 2a and 2b. The radio card readers 2a and 2b radiate question signals at certain intervals of time in synchronism with the reference time signal. Consequently, the interaction generated between the reading devices is evaded.</p> |
