| 摘要 |
The device comprises a piezoelectric element and an electrochromic display element. The piezoelectric element has an output adapted to provide a voltage in response to an activation of the piezoelectric element such as to operate the electrochromic display element which has an input coupled to the output of said piezoelectric element. The electrochromic element provides a visible output dependent on the output of said piezoelectric element (4). The device has a thickness of 60 microns or less. A credit card 20 incorporates the display 28. When the card is flexed to stress the piezoelectric element the voltage applied to the display results in a change in the colour of the display. A sheet of paper 30 e.g. a bank note incorporates the display as a thread 32. When the note is handled, stressing the thread, a colour change occurs providing an indication that the note is genuine. |
