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AssigneeU.S. Philips Corporation
InventorsNigel D. Young, John M. Shannon
Estimating the term…
A matrix array display device has an array of pixels (10) on a substrate (50) which each have a display element (20), for example an electroluminescent display element, and associated control circuit including a storage capacitor (36) and a light sensing element (40) connected thereto for regulating charge stored on the capacitor and responsive, for example, to light emitted from the display element so as to regulate operation of the display element. The light sensing elements (40) comprise thin film semiconductor devices each having a strip of semiconductor material (52) with laterally-spaced, doped, contact regions (53, 54) and the associated storage capacitor (36) is formed by a conductive layer (58) extending substantially transversely of the strip over one contact region with intervening dielectric material. A predetermined relationship between the storage capacitor and photosensitive device characteristics is then ensured even though dimensional variations in component layers may occur due to manufacturing tolerances. Preferably, the photosensitive device comprises a gated device whose gate extends over the semiconductor strip region intermediate the contact regions. The gate dielectric and storage capacitor dielectric may comprise parts of a common layer (56). Alternatively, the conductive layer may be provided at the side of the strip opposite the gate and used also as a shield for ambient light.
A matrix display device comprising on a substrate an array of addressable pixels each having a display element and a display element control circuit for controlling the operation of the display element, wherein the display element control circuit includes a charge storage capacitor and an associated thin film photosensitive semiconductor device coupled to the storage capacitor for regulating charge stored on the storage capacitor in accordance with light falling on the photosensitive device, wherein the photosensitive device comprises a strip of semiconductor material having doped contact regions laterally spaced on the substrate and an intervening region, and wherein the storage capacitor comprises a conductive layer extending substantially transversely of the semiconductor strip over one contact region thereof with a layer of dielectric material being disposed is between the conductive layer and that contact region.
A matrix display device according to anyone of the preceding claims, characterised in that the strip of semiconductor material and the conductive layer at its part overlying the one contact region each have substantially parallel sides and extend generally at right angles to one another.
A matrix display device according to any one of the preceding claims, characterised in that the display element comprises a current-driven light emitting element and in that the photosensitive device is arranged to be responsive to light emitted by the display element.
Dependencies are inferred from the claim text.