Abstract: The invention provides a light emitting device which can suppress the reduction of luminance in accordance with the light emission time and light emission at a high luminance. Moreover, the invention relates to a driving method which can suppress the reduction of luminance in accordance with the light emission time and light emission at a high luminance. The light emitting device of the invention can display a plurality of colors of which brightness and chromaticity are different by visually mixing light emission of a plurality of light emitting elements of which light emission colors are different. When a visually mixed display color is formed, a white light emission is exhibited.

Abstract: A light emitting device comprising a light emitting element and a first transistor and a second transistor controlling current to be supplied to the light emitting element in a pixel; the first transistor is normally-on; the second transistor is normally-off; a channel length of the first transistor is longer than a channel width thereof; a channel length of the second transistor is equal to or shorter than a channel length thereof; gate electrodes of the first transistor and the second transistor are connected to each other; the first transistor and the second transistor have the same polarity; and the light emitting element, the first transistor and the second transistor are all connected in series.

Abstract: The invention provides a shift register which can operate normally while suppressing a delay of signal and a rounding of waveform. The shift register of the invention includes a plurality of stages of flip-flop circuits each of which includes a clocked inverter. The clocked inverter includes a first transistor and a second transistor which are connected in series, a first compensation circuit including a third transistor and a fourth transistor which are connected in series, and a second compensation circuit including a fifth transistor and a transmission gate. According to the first compensation circuit, a timing at which a signal outputted from the flip-flop circuit rises or falls can be controlled in synchronization with an output of two stages before. The second compensation circuit can control a clock signal input can be controlled.

Abstract: A display device where the influence of variations in current of the light emitting element due to changes in ambient temperature and changes with time can be suppressed. The display device of the invention has a light emitting element, a driving transistor connected in series to the light emitting element, a monitoring light emitting element, a limiter transistor connected in series to the monitoring light emitting element, a constant current source for supplying a constant current to the monitoring light emitting element, and a circuit for outputting a potential equal to an inputted potential. A first electrode of the light emitting element is connected to an output terminal of the circuit through the driving transistor, and a first electrode of the monitoring light emitting element is connected to an input terminal of the circuit through the limiter transistor.

Abstract: The present invention provides a TFT that has a channel length particularly longer than that of an existing one, specifically, several tens to several hundreds times longer than that of the existing one, and thereby allowing turning to an on-state at a gate voltage particularly higher than the existing one and driving, and allowing having a low channel conductance gd. According to the present invention, not only the simple dispersion of on-current but also the normalized dispersion thereof can be reduced, and other than the reduction of the dispersion between the individual TFTs, the dispersion of the OLEDs themselves and the dispersion due to the deterioration of the OLED can be reduced.

Abstract: The invention provides a light emitting device which can suppress the reduction of luminance in accordance with the light emission time and light emission at a high luminance. Moreover, the invention relates to a driving method which can suppress the reduction of luminance in accordance with the light emission time and light emission at a high luminance. The light emitting device of the invention can display a plurality of colors of which brightness and chromaticity are different by visually mixing light emission of a plurality of light emitting elements of which light emission colors are different. When a visually mixed display color is formed, a white light emission is exhibited.

Abstract: A low power consumption shift register which inputs a CK signal with a low voltage with almost no effect of variation in characteristics of transistors. In the invention, an input portion of an inverter is set at a threshold voltage thereof and a CK signal is inputted to the input portion of the inverter through a capacitor means. In this mariner, the CK signal is amplified, which is sent to the shift register. That is, by obtaining the threshold potential of the inverter, the shift register which operates with almost no effect of variation in characteristics of transistors can be provided.

Abstract: No need of lowering off-current of a switching transistor, fewer luminance variations of a light emitting element between pixels due to characteristic variations of a driving transistor, and less risk of steps due to increase in the number of wirings. A video signal for light emission or non-emission of a pixel is input to a gate of a current controlling transistor operated in a linear region, which is connected in series with the driving transistor, through a switching transistor. Since a voltage Vds between a source and a drain of the current controlling transistor is small, small changes in a voltage Vgs between a gate and a source thereof do not affect a current flowing in a load. The current flowing in the light emitting element is determined by the driving transistor operated in a saturation region, and a fixed potential is input to the gate thereof during light emission.

Abstract: The invention provides a display device and an electronic device, each of which has one of a structure in which a substrate provided with a light emitting element which performs bottom light emission and a substrate provided with a light emitting element which performs top light emission are attached, and a structure in which two substrates, each of which is provided with a light emitting element which performs bottom light emission are attached. By attaching two substrates, each of which is provided with a light emitting element, displays are provided on the front and back of the display device, thus a high added value can be realized. One of the two substrates, each of which is provided with a light emitting element also functions as a sealing substrate for another substrate, thus a compact, thin, and lightweight display device can be obtained.

Abstract: The present invention provides a TFT that has a channel length particularly longer than that of an existing one, specifically, several tens to several hundreds times longer than that of the existing one, and thereby allowing turning to an on-state at a gate voltage particularly higher than the existing one and driving, and allowing having a low channel conductance gd. According to the present invention, not only the simple dispersion of on-current but also the normalized dispersion thereof can be reduced, and other than the reduction of the dispersion between the individual TFTs, the dispersion of the OLEDs themselves and the dispersion due to the deterioration of the OLED can be reduced.

Abstract: A light emitting device and an element substrate which are capable of suppressing variations in the 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. According to the invention, a driving transistor also serves as an erasing transistor and the driving transistor is operated in a saturation region. The gate of the driving transistor is connected to an erasing scan line and it can be selected whether or not to flow current by a potential of the erasing scan line. In addition, a current controlling transistor which operates in a linear region is connected in series to the driving transistor, thus a video signal transmitting a light emission or non-emission of a pixel is input to the gate of the current controlling transistor through a switching transistor.

Abstract: In a method for manufacturing a display device having a light emitting element, a first base insulating film, a second base insulating film, a semiconductor layer, and a gate insulating film are formed in this order over a substrate. A gate electrode is formed over the gate insulating film to overlap with at least a part of the semiconductor layer, and a portion to be a pixel portion of the gate insulating film and the second base insulating film is doped with at least one conductive type impurities. An opening portion is formed by selectively etching the gate insulating film and second base insulating film that are each doped with impurities. The first base insulating film is exposed in a bottom face of the opening portion. Subsequently, an insulating film is formed to cover the opening portion, the gate insulating film, and the gate electrode, and a light emitting element is formed over the insulating film to overlap with at least a part of the opening portion.

Abstract: The present invention provides a shift register which can operate favorably without providing a level shift portion.

Abstract: The invention provides a display device with high image quality and high definition, a driving method thereof and an element substrate. Further, the invention provides a display device with improved degradation of a light emitting element, a driving method thereof and an element substrate. The display device of the invention has a first transistor, a second transistor, a third transistor, a light emitting element, a source driver, a first gate driver, and a second gate driver. A gate electrode of the first transistor is connected to a gate line, one of a source electrode and a drain electrode thereof is connected to a source line and the other is connected to a gate electrode of the third transistor. The light emitting element, the second transistor and the third transistor are connected in series between a first power source and a second power source.

Abstract: A low power consumption shift register which inputs a CK signal with a low voltage with almost no effect of variation in characteristics of transistors. In the invention, an input portion of an inverter is set at a threshold voltage thereof and a CK signal is inputted to the input portion of the inverter through a capacitor means. In this manner, the CK signal is amplified, which is sent to the shift register. That is, by obtaining the threshold potential of the inverter, the shift register which operates with almost no effect of variation in characteristics of transistors can be provided. A level shifter of the CK signal is generated from an output pulse of the shift register, therefore, the low power consumption shift register having the level shifter which flows a shoot-through current for a short period can be provided.

Abstract: The invention provides a shift register which can operate normally while suppressing a delay of signal and a rounding of waveform. The shift register of the invention includes a plurality of stages of flip-flop circuits each of which includes a clocked inverter. The clocked inverter includes a first transistor and a second transistor which are connected in series, a first compensation circuit including a third transistor and a fourth transistor which are connected in series, and a second compensation circuit including a fifth transistor and a transmission gate. According to the first compensation circuit, a timing at which a signal outputted from the flip-flop circuit rises or falls can be controlled in synchronization with an output of two stages before. The second compensation circuit can control a clock signal input can be controlled.

Abstract: The invention provides a light emitting device which is capable of displaying on both sides, has a small volume, and is capable of being used as a module. A light emitting element represented by an EL element and the like is used in a pixel portion, and two pixel portions are provided in one light emitting device. A first pixel portion has a structure to emit light only from a counter electrode side of the light emitting element. A second pixel portion has a structure to emit light only from a pixel electrode side of the light emitting element. That is, in the first pixel portion and the second pixel portion, directions of light emission are reverse in front and back.

Abstract: In a light emitting apparatus, all pixels are fabricated using monochrome light-emitting materials. Since the light transmittances of color filters or color conversion layers are not uniform among red (R), green (G), and blue (B), exact white color cannot be displayed. In the present invention, dots for producing these colors of light, i.e., red (R), green (G), and blue (B), are arranged parallel to writing scan lines and to erasing scan lines. The brightnesses are made uniform by controlling the emission times of the emitted colors of light. According to the brightnesses obtained after passage through the colored layer with the lowest light transmittance, the emission times of colors of light passed through the other colored layers are shortened. Thus, as the brightness differences after passage can be reduced, the light emitting apparatus can display exact white color.

Abstract: Semiconductor elements deteriorate or are destroyed due to electrostatic discharge damage. The present invention provides a semiconductor device in which a protecting means is formed in each pixel. The protecting means is provided with one or a plurality of elements selected from the group consisting of resistor elements, capacitor elements, and rectifying elements. Sudden changes in the electric potential of a source electrode or a drain electrode of a transistor due to electric charge that builds up in a pixel electrode is relieved by disposing the protecting means between the pixel electrode of the light-emitting element and the source electrode or the drain electrode of the transistor. Deterioration or destruction of the semiconductor element due to electrostatic discharge damage is thus prevented.

Abstract: The invention provides a light emitting device which is capable of displaying on both sides, has a small volume, and is capable of being used as a module. A light emitting element represented by an EL element and the like is used in a pixel portion, and two pixel portions are provided in one light emitting device. A first pixel portion has a structure to emit light only from a counter electrode side of the light emitting element. A second pixel portion has a structure to emit light only from a pixel electrode side of the light emitting element. That is, in the first pixel portion and the second pixel portion, directions of light emission are reverse in front and back.