A transaction card system includes a transaction card with a display tag for displaying short term information, the character display having optical states that are stable without power and viewable from one side of the display tag and an array of electrical contacts for electrically addressing the character...http://www.google.com.hk/patents/US7925538?utm_source=gb-gplus-share專利 US7925538 - Card with embedded bistable display having short and long term information
