El display driver and el display

Abstract

A pulse having a width of 20H is inserted into STV in correspondence with a vertical blanking period (a period of 21H), and the speed of CKV is increased to 12 times the original speed over the period of 21H at the same time the pulse becomes High. A video signal in the vertical blanking period is at a black level, so that black is written into all organic EL elements in the period. An organic EL display continues to display black for a time period elapsed until a video is next written by the original line selection pulse. The video signal is corrected such that the shorter a video display time period provided to the EL element becomes, the higher the input video luminance of the EL element becomes in order to display black.

Description

technical field [0001] The present invention relates to a driving device and an EL display device for driving a display composed of EL (Electroluminescence) elements based on image signals. Background technique [0002] An organic EL element, for example, has a structure in which an ITO transparent anode 52 , a hole transport layer 53 , an organic light emitting layer 54 , an electron transport layer 55 , and a cathode 56 are stacked on a glass substrate 51 in this order, as shown in FIG. 8 . When electrons and holes are respectively injected from the cathode 56 and the anode 52 by the power supply 57, the organic molecules become excited by recoupling these electrons and holes in the organic light-emitting layer 54, and return to the original state ( ground state), light is emitted from the organic light emitting layer 54 . The energy when electrons and holes are recoupled is not all emitted as light to the outside, but part of it is turned into heat, which raises the temp...

AI Technical Summary

Problems solved by technology

[0005] When an image of a black-and-white checkered pattern is continuously displayed for a long time on an organic EL display driven as described above, the temperature of the organic EL elements displaying black will not rise because they do not accept energy. , but the organic EL element that displays white is always receiving energy continuously. Since a part of the received energy is converted into heat, the temperature continues to rise, which will reduce the brightness

In this state, although there is no sense of incongruity in the image, if you want to display an image that is all gray after the image, for example, the organic EL element after the temperature rise and the temperature that has not risen The luminance of organic EL elements is lower than that of organic EL elements, so the pattern of white ground and black grid will be seen indistinctly

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