Electroluminescent display device and driving method thereof

Abstract

A controller stores image signals Sp represented as binary values for every unit of frame. The controller divides one frame into a plurality of sub-frames representing an image by image data of two gradation levels, in accordance with respective figures of the stored image signals Sp for one frame. The image data of two gradation levels for each of the sub-frames is written into capacitors Cp from a drain driver, for every row. When the image data is '1', a drive transistor is turned on. A common driver applies a voltage of a predetermined level for every sub-frame, to control the voltage applied between electrodes of an organic EL element. As a result, the organic EL element emits light with brightness which differs between sub-frames. Images of the sub-frames are visually synthesized, so that gradation is expressed in one frame.

Description

technical field [0001] The present invention relates to an electroluminescent device and its driving method, and more particularly, to a display device suitable for organic electroluminescent device or organic EL element hierarchical display and its driving method. Background technique [0002] As mobile computing becomes more popular, the demand for flat display devices is increasing. As a flat-panel display device, a liquid crystal display device is generally used. However, liquid crystal display devices have problems of narrow viewing angle and low response characteristics. [0003] On the contrary, attention has recently been paid to a display device realizing display by light emission using an organic electroluminescent element as another flat type display device having a wide viewing angle and excellent response characteristics. The pixels of the organic electroluminescent panel used in such a display device are respectively composed of an organic EL element 31, an e...

AI Technical Summary

Problems solved by technology

However, liquid crystal display devices have problems of narrow viewing angle and low response characteristics.

As a result, the value of the current flowing through the organic EL element 31 is greatly changed, or in other words, the number of holes and electrons is greatly changed, so that even if an identical signal is output to the drain line DL, the amount emitted by the organic EL element 31 The amount of light also changes for each pixel, causing the quality of the image displayed on the organic EL panel to be degraded

[0007] The above-mentioned problems lead to another defect that the yield of the organic EL panel decreases

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