System for scanning information from moving objects employing automatic light control.

摘要

A system and method are disclosed for automatically controlling the light intensity of a light source (15) as a function of the amount of light received by a photosensor (21). In a preferred embodiment the light source (15) illuminates a reference background (11) which, in turn, reflects the light incident thereon to a photosensor (21) in a video camera. In response to this reflected light, the photosensor (21) produces a video signal which is proportional to the amount of light reflected thereon. A first means (25, 27, 29) is responsive to the reception of the video signal over a preselected period of time for providing a first signal which is proportional to the amount of reflected light received by the photosensor over that preselected period of time. A second means (31) is responsive to the first signal for generating a control signal to automatically cause an adjustable power supply (35) to change the voltage applied to the light source (15) as a function of the amplitude of the control signal.