Electroluminescent display having compensated analog signal for activating the driving transistor

Abstract

Apparatus for providing an analog drive transistor control signal to the gate electrode of a drive transistor in a drive circuit that applies current to an EL device, the drive circuit including a first supply electrode of the drive transistor and the EL device connected to a second supply electrode of the drive transistor, comprising a measuring circuit for measuring the current passing through the supply electrodes at different times to provide an aging signal representing variations in the characteristics of the drive transistor and EL device caused by operation of the drive transistor andEL device over time; a compensator for changing a linear code value in response to the aging signal to compensate for the variations in the characteristics of the drive transistor and EL device; and a linear source driver for producing the analog drive transistor control signal in response to the changed linear code value.

Description

technical field [0001] The present invention relates to controlling an analog signal applied to a drive transistor for providing current through an electroluminescent device. Background technique [0002] Flat panel displays have attracted great interest as information displays for computing, entertainment, and communication. Electroluminescence (EL: Electroluminescent) flat panel display technologies such as OLED (Organic Light-emitting Diode) technology and liquid crystal displays (LCD: Liquid-Crystal Display) and plasma display panels (PDP: Plasma Display Panel) Compared with other technologies, it provides advantages in color gamut, brightness and power consumption. However, the performance of EL displays degrades over time. In order to provide high quality images over the lifetime of the display, this degradation must be compensated. [0003] EL displays typically include an array of identical sub-pixels. Each sub-pixel includes a drive transistor (usually a thin-fi...

AI Technical Summary

Problems solved by technology

Such an approach is capable of compensating for changes in all three aging factors, but requires either a very accurate external light sensor, or a light sensor integrated in each sub-pixel

External photosensors add cost and complexity to the device, while integrated photosensors add subpixel complexity and electronics size with attendant performance degradation

[0015] Existing V th compensation schemes are not without their drawbacks, and they are rarely able to compensate V oled increase and OLED efficiency loss

while those capable of compensating for each subpixel’s V th The offset solution is at the cost of panel complexity and lower yield

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