Method and apparatus for calibrating display devices and automatically compensating for loss in their efficiency over time

A method for calibrating a display device comprising an array of individually adjustable discrete light emitting devices (pixels) using a photodetector, the method comprising:

• a) observing with said photodetector a first area of said display device array forming a first level sub-array having a first number of pixels and adjusting each of said pixels within said first sub-array to a desired light output;
• b) observing with said photodetector a second area forming a first level second sub-array and adjusting each of said pixels within said second sub-array to the desired light output;
• c) repeating steps (a) and (b) until all of the display pixels have been adjusted to the desired light output;
• d) observing with said photodetector another first area of the device array containing a plurality of said first level sub-arrays to form a second level sub-array;
• e) adjusting as a unit each of said first level sub-arrays in said second level sub-array, to have a common light output;
• f) observing with said photodetector another second level sub-array containing a plurality of said first level sub-arrays to form another second level sub-array;
• g) adjusting as a unit each of said first level sub-arrays in said another second level sub-array, to have a common light output;
• h) repeating steps (e) through (g) until all of the display first level sub-arrays have been adjusted to have common outputs;
• i) repeating steps (d) through (h) with respectively larger sub-arrays until the sub-array has a size that spans the display array.

Apparatus for calibrating a display device comprising an array of individually adjustable discrete light emitting devices (pixels), the apparatus comprising;

• a light detector which receives light emitted by the display device;
• light measuring means, coupled to the light detector, for measuring light output of a portion said display device array;
• adjusting means, responsive to the light measuring means for controlling the portion of the display device array to change the light output of the portion of the display device array;
• an xyz translation stage, which moves the light detector parallel to the display device to capture light emitted by respectively different portions of the display device and which moves the light detector perpendicular to the display device to cause the light measuring means to receive light from different-sized portions of the display device array;
• a controller coupled to the light detector, the light measuring means, the adjusting means and the translation stage for moving the light detector to measure the light output of respective first portions of the display device array, each of the first portions being substantially equal in size, for adjusting the respective portions of the display device to provide a desired light output;
• for moving the light detector to measure light output of respective second portions of the display device array, each of said second portions being substantially equal in size and including a plurality of the first portions;
• and for adjusting each of the second portions to provide substantially equal light output.

Apparatus for calibrating a display device comprising an array of individually adjustable discrete light emitting devices (pixels), the apparatus comprising:

• an array of light detecting elements which receives light emitted by the display device;
• light measuring means, coupled to the array of light detecting elements, for measuring light output of a portion said display device array;
• adjusting means, responsive to the light measuring means for controlling the portion of the display device array to change the light output of the portion of the display device array;
• an xy translation stage, which moves the light detector parallel to the display device to capture light emitted by respective portions of the display device;
• a controller coupled to the array of light detecting elements, the light measuring means, the adjusting means and the translation stage, the controller including
• means for moving the light detector to measure the light output of respective overlapping portions of the display device array, each of the overlapping portions being substantially equal in size and overlapping a previously measured portion in at least one pixel position;
• means for adjusting a first one of the portions of the display device to provide a desired light output;
• and
• means for adjusting each one of the overlapping portions to have a light output substantially equal to the light output of the at least one overlapping pixel position.