Sanyo Electric Co., Ltd.

Hitoshi Yasuda

Kazumasa Takai

Masatoshi Sato

Tomonori Matsumuro

Ryuji Nishikawa

Takashi Ogawa

Yoshinori Saito

Hidenori Chiba

The invention provides an organic EL display device usable for both negative and positive polarity video signals. The organic EL display device of the invention has a polarity switching circuit switching a polarity of a digital video signal. In a case where a display panel is made for a negative polarity video signal, when a negative digital video signal is inputted, this polarity switching circuit lets the negative polarity digital video signal pass therethrough without inverting its polarity. When a positive polarity digital video signal is inputted, this polarity switching circuit inverts a polarity of the positive polarity digital video signal and inverts and switches reference data for a white level and reference data for a black level in order to obtain an accurate inverted image. An output of the polarity switching circuit is converted into an analog video signal through a first D/A converter and outputted to the display panel.

Self-emission type display device

This invention provides a clock switching circuit that can switch clocks without causing a hazard or a distortion of a duty ratio of the clocks. The clock switching circuit of this invention includes a first synchronization circuit that synchronizes a clock selection signal with a first clock, a second synchronization circuit that synchronizes with a second clock the clock selection signal that has been synchronized with the first clock by the first synchronization circuit and a clock selection circuit that outputs '1', that is a high level, in synchronization with the clock selection signal that has been synchronized with the first clock by the first synchronization circuit and after that selects the second clock in synchronization with the clock selection signal that has been synchronized with the second clock by the second synchronization circuit.

Clock switching circuit

The upper limit Vof the driving voltage PVdd is set in such way that the brightness of an organic EL element is lower than the first standard brightness Lwhen the video signal Dm is at the black signal level (V), in an EL display device with the driving source for driving the organic EL element. Also, the lower limit Vof the driving voltage PVdd is set in such way the brightness of the organic EL element is higher than the second standard brightness Lwhen the video signal Dm is at the white signal level (V). The electroluminescent display device displays black and white with a proper contrast.

Display device with controlled driving source

An organic electroluminescent display device includes a plurality of electroluminescent elements and a plurality of thin film transistors. Each of the electroluminescent elements includes an anode, a cathode and a light emitting layer disposed between the anode and the cathode. Each of the thin film transistors drives one of the electroluminescent elements. A first power supply is connected to the thin film transistors and supplies a power supply voltage to the thin film transistors. The first power supply changes the power supply voltage so that luminance of the light emitting layers vary. A second power supply is connected to the electroluminescent elements and supplies a reference voltage to the electroluminescent elements. Because the power supply voltage itself varies, it is easy to adjust the brightness of the display device.

Organic EL display device

An organic EL display device comprises a first TFT ( ) for switching; a second TFT ( ) for driving an organic EL element; and an organic EL element ( ) having an anode ( ), a cathode ( ), an emissive element layer ( ) interposed between both electrodes. Additionally, a first storage capacitor electrode ( ) comprising Cr and a second storage capacitor electrode ( ) also functioning as a p-Si film which is a source ( s) of the first TFT ( ) constitute a first storage capacitor ( ) via a gate insulating film ( ), while said second storage capacitor electrode ( ) and a third storage capacitor electrode ( ) formed by extending a part of a power supply line ( ) for causing the organic EL element ( ) to emit light are arranged to be opposed to each other via an interlayer insulating film to form a second storage capacitor ( ). Thus, it is possible to implement a light emissive display device which achieves bright display while sufficiently holding charges within one pixel without reducing the aperture ratio.

Growing community of inventors

Gifu, Japan

Hitoshi Yasuda