Universal stylus device

A method comprising:

• encoding a pattern onto light emitted from a plurality of pixels of a display by a computing device coupled to the display, wherein each of the pixels has an associated location on the display, wherein the plurality of pixels are organized into quads and each quad comprises four pixels and has an associated location on the display, and further wherein encoding the pattern onto the light emitted from the plurality of pixels comprises adjusting the intensity of one or more of the pixels in each quad according to a sequence of patterns that uniquely identifies the location of each quad;
• receiving the light emitted from the plurality of pixels of the display at an image sensor of a stylus device;
• determining the location of at least one of the pixels based on the received light by the image sensor of the stylus device using the encoded pattern;
• and
• determining a position of the stylus device with respect to the display by the image sensor of the stylus device based on the determined location of the at least one pixel.

A system comprising:

• a computing device;
• a display coupled to the computing device;
• and
• a stylus device comprising:
• an optical element;
• and
• an image sensor, the image sensor adapted to:
• receive light emitted from the display through the optical element, wherein the received light forms an image on the image sensor;
• determine a portion of the image that is in focus;
• determine a radius of the portion of the image that is in focus;
• and
• determine a distance between the stylus device and the display based on the determined radius.