Apple Inc.
Noise reduction in LED sensing circuit for electronic display

Abstract:

Systems, methods, and devices are provided to reduce noise present in sensing circuits used for calibrating light emitting diodes (e.g., organic light emitting diodes) in electronic display devices. Such a system may include a display that renders image data using self-emissive pixels. Values on the pixels may be sensed using a current source that outputs a current and a comparator that receives the current. The comparator changes states when a voltage signal output by the capacitor crosses a first threshold voltage or a second threshold voltage. A controller receives a first time when the comparator component changes states based on the voltage signal, receives a second time when the comparator component changes states based on the voltage signal, determines a current value based on the first time and the second time, and calibrates a pixel based on the current value.