Patent Number: 8,872,093

Title: Calibrated image-sensor-based ambient light sensor

Abstract: An electronic device may be provided with an image sensor for capturing digital images. The image sensor may be used as part of image-sensor-based ambient light sensing circuitry for producing ambient light sensor readings. The image-sensor-based ambient light sensing circuitry may include a reference array. The reference array may be formed from an array of light sensor elements that are matched to elements in the image sensor but that are covered with a light blocking material. Control circuitry can measure current flow into the reference array and the image sensor array and can use current measurements from these arrays in producing a calibrated ambient light sensor reading. The control circuitry may make current measurements by measuring a decay time associated with the voltage of a discharging capacitor. A comparator, pulse generator, and switch may be used in periodically recharging the capacitor. The capacitor may be adjusted to ensure accurate readings.

Inventors: Lee; Chiajen (Irvine, CA), Sharma; Anup (Sunnyvale, CA), Fan; Xiaofeng (San Jose, CA)

Assignee: Apple Inc.

International Classification: H01L 27/146 (20060101); G09G 5/10 (20060101)

Expiration Date: 2018-10-28 0:00:00