Patent ID: 8279328
Filing Date: 2012-10-02
Classification: H04N

Abstract:
1. A high dynamic range CMOS image sensor comprising: a pixel array including a plurality of pixels, each pixel having a photodiode, a first node, and a plurality of transistors including a reset gate transistor connected between a memory node voltage source and the first node, and a transfer gate transistor coupled between the photodiode and the first node; and an exposure control circuit including: second means for determining whether a photodiode charge stored on the selected pixel is above a predetermined value after a predetermined portion of said exposure frame period, for causing said first means to reset said photodiode to the initial photodiode charge only if said stored photodiode charge is above the predetermined value after said predetermined portion of said exposure frame period, and for causing said first means to store a second exposure time value in the selected pixel; and third means for calculating an image data value for said selected pixel using both a final photodiode charge value read from said photodiode of said selected pixel at the end of said exposure frame period, and a final exposure time value read from the selected pixel at the end of said exposure frame period, wherein said final exposure time value is equal to said first exposure time value when said second means determines that said photodiode charge stored on the selected pixel is below the predetermined value.