Movement detection using light intensity variation measurement - by successive comparison of light density differential derivative w.r.t. time

摘要

Circuit detects moving bodies using light intensity variation. The differential derivative of the light density falling on a defined surface is determined w.r.t. time. Successive measured values are compared with one another and differences displayed and/or evaluated. Light is converted into current or voltage by a sensor whose output is input to an operational amplifier via a differentiator. The amplifier output is input to a trigger stage operating a slow level changes whose output is connected to display and/or evaluation circuits via a switch.