Patent ID: 7295129

Claim:
A battery operated device with a battery life indicator comprising a housing, at least one cell located inside said housing, a two-position mechanical switch, an emitting unit and a battery life indicator, wherein: (i) said battery, said mechanical switch and said emitting unit are electrically connected to form a primary circuit and assembled with said housing; (ii) said mechanical switch completes said primary circuit when switched to the first position and interrupts said primary circuit while switched to the second position, thus said emitting unit operates by action of said mechanical switch; (iii) said battery life indicator is comprised of a countdown timer, at least one embedded control button and a liquid crystal display, thus forming a secondary circuit; (iv) said secondary circuit is connected with said primary circuit in parallel with common ground, thus said secondary circuit is always powered; (v) said control button provides a signal to said countdown timer for establishment of an initial runtime value of said battery; (vi) said liquid crystal display is operated by said countdown timer and shows remaining runtime value of said battery starting from the initial runtime value; (vii) said secondary circuit uses an electrical signal derived from said primary circuit to operate said countdown timer; (viii) said countdown timer operates in such a way that, when said primary circuit is interrupted by said mechanical switch, said countdown timer is stopped and current runtime value shown by said liquid crystal display is fixed, while when said primary circuit is completed by said mechanical switch, said countdown timer continues to operate and said liquid crystal display shows current runtime value counting down from the previously fixed runtime value.