Detecting high intensity light in photo sensor
AssigneeFacebook Technologies, LLC
InventorXinqiao Liu
Life of this patent
Estimating the term…
Abstract
Two separate schemes are used for detecting light intensity in low light conditions and high light conditions. In high light conditions, two threshold voltages are set and the time between the crossing of a sensor voltage at the two threshold voltages is measured to determine the light intensity in the high light conditions. In low light conditions, a comparator is used to compare the voltage level of the sensor voltage relative to a reference voltage that increase over time. The time when the reference voltage reaches the sensor voltage level is detected to determine the light intensity in the low light conditions.
Claims19
A pixel in a photo sensor, comprising:
- a photo diode,
- a floating diffusion point, and
- a transistor between the photo diode and the floating diffusion point, a gate of the transistor applied with an intermediate voltage between a turn-off voltage of the transistor and a turn-on voltage of the transistor to transfer charge from the photo diode to the floating diffusion point responsive to an intensity of light incident on the photodiode during an exposure phase exceeding a threshold intensity, the gate of the transistor applied with the turn-on voltage in a sensing phase subsequent to the exposure phase to transfer the charge from the photo diode to the floating diffusion.
A method for operating a pixel, the method comprising:
- applying an intermediate voltage to a gate of a first transistor in an exposure phase, the intermediate voltage between a turn-off voltage of the first transistor and a turn-on voltage of the transistor;
- applying a turn-on voltage to the gate of the first transistor in a sensing phase subsequent to the exposure phase;
- and
- transferring charge from a photodiode to a floating diffusion point in a first substrate responsive to an intensity of light incident on the photodiode during the exposure phase exceeding a threshold intensity.
Dependencies are inferred from the claim text.