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Display drivers

A driver and driver circuit technology, applied to static indicators, instruments, electric solid-state devices, etc., can solve the problems of non-linear voltage-brightness relationship and non-linear charge proportionality, etc.

Inactive Publication Date: 2008-02-27
CAMBRIDGE DISPLAY TECH LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Capacitor 258 is also often non-linear, so that the stored charge is not linearly proportional to the voltage applied to column line 264
This results in a non-linearity in the voltage-brightness relationship of the pixel as photodiode 266 passes (and thus charges) a photocurrent that depends on the intensity of light it receives.

Method used

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Embodiment Construction

[0040] Reference is first made to Fig. 3a, which shows a current controlled organic LED driver circuit 300 with optical feedback according to an embodiment of the present invention. In an active matrix display, typically each pixel is provided with such driver circuitry and other circuitry (not shown) to address the pixel row by row, setting each row to a desired brightness. To provide power and control for the driver circuits and OLED display elements, this active matrix display is provided with a number of electrode control nets including ground (GND) 302 as shown, power or V ss line 304 , row select line 306 and column data line 308 . Each column data line is connected to a programmable constant current reference source (or sink) 324 . It is not part of the driver circuit provided for each pixel, but includes part of the circuit provided for each column. The reference current generator 324 is programmable so that it can be adjusted to a desired level to set the brightness...

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Abstract

Display driver circuitry for electro-optic displays, in particular active matrix displays using organic light emitting diodes. The circuitry includes a driver to drive an electro-optic display element in accordance with a drive voltage, a photosensitive device optically coupled to the electro-optic display element to pass a current dependent upon illumination reaching photosensitive device, a control circuit having a control line coupled to the driver to control the brightness of the electro-optic display element and having a current sense input coupled to the photosensitive device, a current set line for coupling to a reference current generator, and a display element select line to, when active, cause the control circuit to drive the electro-optic display element in accordance with the current set by the reference current generator. The circuit provides improved control of an electro-display element such as an organic LED pixel.

Description

technical field [0001] The present invention relates to a display driver for an electro-optic display, especially a circuit for driving an active matrix organic light emitting diode display. Background technique [0002] Active light-emitting diodes (OLEDs) are a particularly advantageous form of electro-optic displays because they are bright, colorful, rapidly switching, have a wide viewing angle and can be mounted easily and inexpensively on a variety of substrates. Organic LEDs can be made in various colors (or multicolor displays) from polymers or from small molecule materials, depending on the materials used. Examples of polymer-based organic LEDs are described in WO 90 / 13148, WO 95 / 06400 and WO 99 / 48160; examples based on so-called small molecules are described in US 4,535,507. [0003] The basic structure 100 of a typical organic LED is shown in Figure 1a. A glass or plastic substrate 102 supports a transparent anode layer 104 comprising, for example, indium tin oxi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G09G3/32H05B44/00G09G3/20G09G3/30H01L51/50
CPCG09G3/3233G09G2360/148G09G2300/0417Y02B20/345G09G2320/045G09G2300/088G09G2300/0819G09G2300/0842G09G3/30
Inventor 尤安·克里斯托弗·史密斯保罗·理查德·劳特利
Owner CAMBRIDGE DISPLAY TECH LTD