| 摘要 |
Self contained electronic and chemical timers for displaying a preset message, such as "Expired", can be applied to a plurality of products and can be used with a plurality of services. In one form, a timer is activated. A clock (100) drives a timer circuit or a count down circuit (110). When the countdown circuit reaches zero or a count up circuit reaches its maximum value or a programmed value, the state of the output line of the timer (120) will change triggering a switch (130) which will cause a display (140) to indicate that the end of the time interval has been reached. In another form a timer is activated by removing a protective sheet from an adhesive layer, prior to adhering the timer to a surface. Techniques for manufacturing a plurality of timers on a flexible substrate permit timers to be fabricated at low cost. Sheets containing one or more timers can be assembled into a pad of timer sheets that can be activated upon removal from the pad prior to adhering the timer sheet to a surface. A variety of activation mechanisms are described for both electrical and chemical timers. |
