An EL display apparatus according to the present invention includes EL device adapted to emit light at a luminance corresponding to a current fed thereto. A source driver outputs a current higher than a current corresponding to an image signal to the EL device through a source signal line. This operation charges/discharges a parasitic capacitance present in the source signal line. A transistor formed between the EL device and the source driver operates so that the EL device is fed with the current for only a part of a one-frame period. As a result, the El device emits light for only the part of the period.

The present invention provides a TFT substrate structure, comprising a Switching TFT and a Driving TFT, and the Switching TFT comprises a first active layer, and the Driving TFT comprises a second active layer, and the first active layer and the second active layer are made by the same or different materials and the electrical properties of the Switching TFT and the Driving TFT are different. According to the different functions of the different TFTs, the present invention employs different working structures for the Switching TFT and the Driving TFT to respectively implement deposition and photolithography, and employs different materials for the active layers of the Switching TFT and the Driving TFT to differentiate the electrical properties of different TFTs in the TFT substrate. Accordingly, the accurate control to the OLED with lowest cost can be realized.

An EL display apparatus according to the present invention includes an EL device adapted to emit light at a luminance corresponding to a current fed thereto. A source driver outputs a current higher than a current corresponding to an analog video signal to the EL device through a source signal line. This operation charges/discharges a parasitic capacitance present in the source signal line. A second gate driver circuit controls a transistor formed between the EL device and the source driver to operate so that the EL device is fed with the current for only a part of a one-frame period. As a result, the El device emits light for only the part of the period.

Disclosed is a semiconductor device having a first transistor and a second transistor over the first transistor. The first transistor includes a first semiconductor, and the second transistor includes an oxide semiconductor that is different from the first semiconductor. A gate of the first transistor is electrically connected to a source or drain electrode of the second transistor. The second transistor has a semiconductor layer including the oxide semiconductor over the source and drain electrodes and a gate electrode over the semiconductor layer with an insulating layer therebetween.

A semiconductor device capable of retaining data for a long time is provided. The semiconductor device includes first to third transistors, a fourth transistor including first and second gates, first to third nodes, a capacitor, and an input terminal. A source of the first transistor is connected to the input terminal. A drain of the first transistor and a source of the second transistor are connected to the first node. A gate of the second transistor, a drain of the second transistor, and a source of the third transistor are connected to the second node. A gate of the third transistor, a drain of the third transistor, the capacitor, and the second gate of the fourth transistor are connected to the third node.

A light emitting device and an element substrate which are capable of suppressing variations in luminance intensity of a light emitting element among pixels due to characteristic variations of a driving transistor without suppressing off-current of a switching transistor low and increasing storage capacity of a capacitor. A gate potential of a driving transistor is connected to a first scan line or a second scan line, and the driving transistor operates in a saturation region. A current controlling transistor which operates in a linear region is connected in series to the driving transistor. A video signal which transmits a light emission or non-emission of a pixel is input to the gate of the current controlling transistor through a switching transistor.

A display apparatus includes: a substrate; a first semiconductor layer on the substrate, and including a silicon semiconductor; a second semiconductor layer on the first semiconductor layer, and including an oxide semiconductor; a first conductive layer on the second semiconductor layer; at least one metal layer between the first semiconductor layer and the first conductive layer; and a first contact hole to electrically connect the first semiconductor layer to the first conductive layer. An inner surface of the first contact hole includes a side surface of the at least one metal layer.

A display device having a plurality of pixel structures, each of the plurality of the pixel structures including: a substrate; a first active pattern on the substrate; a first gate line on the first active pattern and extending in a first direction; a first connecting pattern on the first gate line and configured to transmit an initialization voltage; a second connecting pattern on the first connecting pattern and electrically connected to the first active pattern and the first connecting pattern; and a first electrode on the second connecting pattern and configured to be initialized in response to the initialization voltage.

The display apparatus includes a substrate, a first active layer disposed on the substrate, a first gate layer disposed on a layer covering the first active layer, the first gate layer including a first gate electrode, a second gate layer disposed on a layer covering the first gate layer, the second gate layer including an initialization line including a first part of a second electrode; a second active layer disposed on a layer covering the second gate layer, the second active layer including a second active region overlapping the first part of the second electrode; a third gate layer disposed on a layer covering the second active layer, the third gate layer including a second part of the second electrode overlapping the second active region; and a first source/drain layer disposed on a layer covering the third gate layer, the first source/drain layer including a first connection line.

By applying an AC pulse to a gate of a transistor which easily deteriorates, a shift in threshold voltage of the transistor is suppressed. However, in a case where amorphous silicon is used for a semiconductor layer of a transistor, the occurrence of a shift in threshold voltage naturally becomes a problem for a transistor which constitutes a part of circuit that generates an AC pulse. A shift in threshold voltage of a transistor which easily deteriorates and a shift in threshold voltage of a turned-on transistor are suppressed by signal input to a gate electrode of the transistor which easily deteriorates through the turned-on transistor. In other words, a structure for applying an AC pulse to a gate electrode of a transistor which easily deteriorates through a transistor to a gate electrode of which a high potential (VDD) is applied, is included.