Abstract: This invention is intended to provide a technique for improving characteristics of a TFT and realizing a structure of the TFT optimum for driving conditions of a pixel section and a driving circuit by using a small number of photomasks. The TFT includes a first electrode, a first insulating film put between a semiconductor film and the first electrode, a second electrode, and a second insulating film put between the semiconductor film and the second electrode. The first electrode and the second electrode are overlapped with each other, with a channel formation region of the semiconductor film put between the first electrode and the second electrode, and a constant voltage is always applied to the first electrode.

Abstract: There is provided an EL light-emitting device with less uneven brightness.

Abstract: There is provided an EL light-emitting device with less uneven brightness.

Abstract: An object of the present invention is to provide a technique for improving characteristics of a TFT and realizing the structure of the TFT optimal for driving conditions of a pixel section and a driving circuit, using a smaller number of photo masks. A semiconductor device has a semiconductor film, a first electrode, and a first insulating film sandwiched between the semiconductor film and the first electrode, and further has a second electrode, and a second insulating film sandwiched between the semiconductor film and the second electrode. The first electrode and the second electrode overlap with each other across a channel-formed region which the semiconductor film has. A constant voltage is applied to the first electrode at any time.

Abstract: This invention is intended to provide a technique for improving characteristics of a TFT and realizing a structure of the TFT optimum for driving conditions of a pixel section and a driving circuit by using a small number of photomasks. The TFT includes a first electrode, a first insulating film put between a semiconductor film and the first electrode, a second electrode, and a second insulating film put between the semiconductor film and the second electrode. The first electrode and the second electrode are overlapped with each other, with a channel formation region of the semiconductor film put between the first electrode and the second electrode, and a constant voltage is always applied to the first electrode.

Abstract: There is provided a light emitting device in which low power consumption can be realized even in the case of a large screen. The surface of a source signal line or a power supply line in a pixel portion is plated to reduce a resistance of a wiring. The source signal line in the pixel portion is manufactured by a step different from a source signal line in a driver circuit portion. The power supply line in the pixel portion is manufactured by a step different from a power supply line led on a substrate. A terminal is similarly plated to made the resistance reduction. It is desirable that a wiring before plating is made of the same material as a gate electrode and the surface of the wiring is plated to form the source signal line or the power supply line.

Abstract: A method of repairing a light emitting device which makes high quality image display possible even if a pin hole is formed during formation of an EL layer is provided. The method of repairing a light emitting device is characterized in that a reverse bias voltage is applied to an EL element at given time intervals to thereby reduce a current flowing into an EL element when the reverse bias voltage is applied to the EL element.

Abstract: The number of operation keys is normally on the order of 12 to 20, corresponding to numeral keys and specialized keys, even for a portable telephone device capable of sending signals to, and receiving signals from, the Internet. In order to input Japanese language characters, including kanji. and specialized characters as data, a complex operation is necessary for switching the input mode. With the present invention, display devices are formed in operation keys for inputting information to electronic devices such as portable information terminals, typically portable telephone devices, and information terminals, typically personal computer or stationary telephone devices. A user is able to recognize the operation keys by characters, symbols, and numerals displayed in the operation keys by the display devices. The user is able to recognize the operation keys even in a dark location in accordance with the present invention.

Abstract: There is provided an EL light-emitting device with less uneven brightness.

Abstract: The present invention is intended to suppress power consumption of an EL display. In accordance with the brightness of an image to be displayed in a pixel portion, the contrast of the image is determined whether to be inverted or not, and the number of bits of the digital video signal to be input into the pixel portion is reduced, and the magnitude of a current to flow through the EL element is allowed to be maintained at a constant level even when a temperature of an EL layer changes by providing the EL display with another EL element to be used for monitoring a temperature.

Abstract: The present invention is intended to suppress power consumption of an EL display. In accordance with the brightness of an image to be displayed in a pixel portion, the contrast of the image is determined whether to be inverted or not, and the number of bits of the digital video signal to be input into the pixel portion is reduced, and the magnitude of a current to flow through the EL element is allowed to be maintained at a constant level even when a temperature of an EL layer changes by providing the EL display with another EL element to be used for monitoring a temperature.