Patent ID: 7668452

Claim:
An automatic exposure control apparatus employed by an image sensor module comprising a lens unit receiving an incident image, an image sensing unit having a shutter, photographing the image from lens unit via the shutter, and converting the image into an electrical image signal, and an image signal processing unit restoring the image signal from the image sensing unit to an image, the apparatus comprising: a brightness calculator extracting average brightness from the image signal of the image signal processing unit; a brightness adjustment determiner determining whether to fix or adjust a speed of the shutter based on a brightness error value corresponding to an error between the average brightness from the brightness calculator and reference brightness; an adjustment path controller directly controlling the speed of the shutter to be adjusted when the brightness error value is included within a predetermined minimum error range and controlling the speed of the shutter to be filtered when the brightness error value is out of the predetermined minimum error range; a digital filter filtering the brightness error value according to control of the adjustment path controller and outputting a filtered brightness error value; a shutter speed adjuster adjusting a present shutter speed value by using one of the brightness error value from the adjustment path controller and the filtered brightness error value from the digital filter and providing a control shutter speed value; and a shutter speed controller controlling a speed of the shutter of the image sensing unit by using the control shutter speed value.