Patent ID: 8310413

Claim:
An active matrix display device comprising a plurality of printing dams and an array of display pixels, each pixel comprising: a current-driven light emitting display element comprising an area of light emitting material sandwiched between electrodes; a light-dependent device for detecting the brightness of the display element, wherein the light-dependent device is located laterally outside of the area of the light emitting material defined by the vertical planar edges of the light emitting layer of the light emitting material, and separated from the light emitting material by at least one insulating layer, wherein the vertical planar edges of the light emitting material are defined in a direction between a top and a bottom electrode of the light-dependent device wherein the light dependent device is located in the same horizontal plane as the light emitting material of the light emitting display element and is configured to enclose the light emitting material on at least three sides, and wherein the light dependent device is directly illuminated from light emitted from a side face of the light emitting display element and travels in a horizontal plane from said light emitting display to said light dependent device, wherein the light-dependent device is formed beneath one of said plurality of printing dams, a drive transistor circuit for driving a current through the display element, wherein the drive transistor is controlled in response to the light-dependent device output.