CMOS image sensor with pixel level gain control
December 18, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesSolid-state imaging device having photo-electric conversion elements and other circuit elements arranged to provide improved photo-sensitivity Solid-state image array with simultaneously activated line drivers CMOS image sensor with pixel level A/D conversion Resettable pixel amplifier for an image sensor array Photo-electric conversion apparatus with gain controllable amplifiers Camera having an adaptive gain control Low light level solid state image sensor Pixel circuit with integrated amplifer Correlated double sampling with up/down counter Digitally gain-controlled amplifying device, and camera using such a device InventorAssigneeApplicationNo. 09216699 filed on 12/18/1998US Classes:348/301Pixel amplifiersExaminersPrimary: Garber, Wendy R.Assistant: Misleh, Justin Foreign Patent References
International ClassesH04N 5235H04N 314 H04N 5335 AbstractAn image sensor and method of sensing an image provides a variable amplifier at each pixel, thereby expanding the dynamic range of the sensor. An image sensor core (500) comprises a plurality of pixel sensors (510). Each pixel sensor preferably includes a photosensitive element (310), a variable amplifier (312), and an analog-to-digital converter (“ADC”) (314). The ADC (512) includes a comparator (512) coupled to a latch/shift register (514). The comparator (512) receives the output of the variable amplifier (312) and a ramp signal and produces an output when the ramp signal exceeds the amplifier (312) output. The latch/shift register (514) latches a count signal corresponding to the ramp signal when triggered by the comparator (512). In operation, the photosensitive element (310) is exposed to light for a first integration period. The variable amplifier (312) amplifies the resulting photocharge by the maximum possible amount. The ADC (314) converts the photocurrent to a digital signal and latches the five most significant bits in memory (514). These five bits are provided in parallel to the variable amplifier (312) to set the amplification level. Then, the photosensitive element (310) is exposed to light for a second integration period and the resulting photocharge is amplified at the set amplification level. The output of the amplifier (312) is digitized by the ADC (314) and the latch/shift register (514) stores the 12-bit result. The five bits selecting the amplification level and the 12-bit result provide the image sensor with 17 bits of dynamic range.Field of SearchCombined automatic gain control and exposure control (i.e., sensitivity control)Readout of solid-state image sensor considered or altered With amplifier Pixel amplifiers X - Y architecture Including switching transistor and photocell at each pixel site (e.g., "MOS-type" image sensor) Solid-state image sensor Having gain control means Including gain control means With amplification control Automatic control for increasing converter range (e.g., gain ranging, automatic gain control) Converter is part of control loop Analog input compared with static reference Imaging array Photodiodes accessed by FETs | |
