Digital meter automatic off power supply circuit

Abstract

A digital display instrument with an automatic power-off device built-in which comprises a control circuit, a timing circuit and a display detection circuit. The power of the instrument is controlled by a push-button switch so that when the push-button switch is pressed down and released immediately, the power is turned on. If the push-button switch is pressed down and held for about 1.5 seconds, however, the power is turned off. The power can be turned off automatically by detecting if the instrument has not been used for a pre-set period of time. After the power is turned on, the display detection circuit will monitor the reading on the display continuously to determine whether the instrument is in use or not. If the detection shows the instrument is still in use, the timer will be reset to maintain the power on for another period of time. However, if a condition of not being in use is detected within the preset period of time, the power will be turned off automatically.

Dependencies are inferred from the claim text.