Abstract: An AM-OLED display device is provided in which dispersion in OLED element driver currents is sufficiently suppressed is taken as an objective. The present invention places a plurality of transistors into a parallel connection state during write-in of a data current into pixels, and places the plurality of transistors into a series connection state when light emitting elements emit light. As a result, even if dispersions exist between the plurality of transistors structuring a driver element within the same pixel, the influence of the dispersions can be greatly suppressed, and therefore irregularities in the brightness of emitted light across pixels, of an order such that it causes problems in practical use, can be prevented.

Abstract: The light emitting device according to the present invention is characterized in that a gate electrode comprising a plurality of conductive films is formed, and concentrations of impurity regions in an active layer are adjusted with making use of selectivity of the conductive films in etching and using them as masks. The present invention reduces the number of photolithography steps in relation to manufacturing the TFT for improving yield of the light emitting device and shortening manufacturing term thereof, by which a light emitting device and an electronic appliance are inexpensively provided.

Abstract: An electro-optical device having a plurality of pixels including a plurality of EL elements, wherein the electro-optical device provides a gray scale display by controlling a period of time at which the plurality of the EL elements emit light in one frame period; the plurality of the EL elements have a first electrode and a second electrode; the first electrode is held at a constant potential; and a potential of the second electrode changes in such a manner that a polarity of an EL driving voltage, which is a difference between the potentials applied to the first and second electrodes, is inverted for each one frame period.

Abstract: To provide a display device and its driving method free from lack of writing time, which usually accompanies an increase in size of a display device and enhancement in definition. Therefore, there is provided a display device and a driving method in which x (x is a natural number equal to or larger than 4) data lines are placed in each column to simultaneously supply video signals to x pixels through the x data lines. The present invention makes it possible to supply video signals to x pixels simultaneously as opposed to conventional dot sequential driving where a signal is supplied to one pixel at a time. Furthermore, a display device of the present invention and its driving method make it possible to supply video signals to (x×n) pixels at once as opposed to conventional linear sequential driving where only n pixels in the first to last (the last column is the n-th column) columns receive signals simultaneously.

Abstract: An electro-optical device having a plurality of pixels including a plurality of EL elements, wherein the electro-optical device provides a gray scale display by controlling a period of time at which the plurality of the EL elements emit light in one frame period; the plurality of the EL elements have a first electrode and a second electrode; the first electrode is held at a constant potential; and a potential of the second electrode changes in such a manner that a polarity of an EL driving voltage, which is a difference between the potentials applied to the first and second electrodes, is inverted for each one frame period.

Abstract: The invention provides a current data amplifier circuit of which output current value is accurate even when transistors with large variation in electrical characteristics are used. According to the invention, a plurality of transistors configuring a driving element is used in a series connection state when inputting current and in a parallel connection state when outputting current. Thus, is it significantly suppressed that the variation are not reflected on the output current value even when the plurality of transistors configuring the driving element have variation.

Abstract: A method of driving a light emitting device in which a plurality of pixels having a light emitting element are formed, characterized by including: setting j display periods (where j is a natural number) to appear in one frame period, each of the j display periods corresponding to one bit of a k-bit digital video signal (where k is a natural number); and subjecting lower n bits of the k bits (where n is a natural number, j?k?n) to one or both of dither processing and error diffusion processing to thereby select whether the pixels turn on or turn off in each of the j display periods according to a (k?n)-bit digital video signal that is converted from the k-bit digital video signal.

Abstract: A simple DA converter circuit which reads in digital voltage value data and outputs analog current value data is provided. The DA converter circuit according to the invention can be applied, for example, to a data driver circuit of an AM-OLED display device. The DA converter circuit comprises a current output circuit comprising a plurality of drive transistors. Gate electrodes of the transistors are electrically connected to each other, and a switch is provided between the gate electrode and drain electrode of each drive transistor.

Abstract: A current data compression circuit of which output current value is accurate even when transistors with large variations in electrical characteristics are used. The current data compression circuit is an electronic circuit comprising a drive element including a plurality of transistors and a means for switching over a series connection state and a parallel connection state of the transistors. An inputted current is compressed for output by the current data compression circuit. Or, the current data compression circuit is an electronic circuit comprising a drive element including a plurality of transistors in which the transistors are used in parallel connection states when inputting current and in series connection states when outputting current.

Abstract: There is provided an electronic device having high reliability and high color reproducibility. A pixel structure is made such that a switching FET (201) and an electric current controlling FET (202) are formed on a single crystal semiconductor substrate (11), and an EL element (203) is electrically connected to the electric current controlling FET (202). The fluctuation in characteristics of the electric current controlling FET (202) is very low among pixels, and an image with high color reproducibility can be obtained. By taking hot carrier measures in the electric current controlling FET (202), the electronic device having high reliability can be obtained.

Abstract: In a display device having a light emitting element, an accurate setting operation needs much time, unless a current value of the signal current (video signal) is set to high value. On the contrary, the driving current value for causing a light emitting element to emit light is very small. Therefore, it is difficult to perform an accurate setting operation. However, according to the present invention, the current source circuit includes plural transistors. The plural transistors are connected in parallel when the setting operation is performed on the current source circuit, whereas the plural transistors are connected in series when the light emitting element is caused to emit light. Further, the speed of the setting operation is increased because a light emitting element is capable of emitting light with a constant luminance and a current value to set up a current source circuit is higher than a driving current value when a light emitting element emits light.

Abstract: There is provided an electronic device having high reliability and high color reproducibility. A pixel structure is made such that a switching FET (201) and an electric current controlling FET (202) are formed on a single crystal semiconductor substrate (11), and an EL element (203) is electrically connected to the electric current controlling FET (202). The fluctuation in characteristics of the electric current controlling FET (202) is very low among pixels, and an image with high color reproducibility can be obtained. By taking hot carrier measures in the electric current controlling FET (202), the electronic device having high reliability can be obtained.

Abstract: A circuit for driving an organic light emitting element by alternating current in an active matrix organic light emitting display is provided. A circuit of a pixel provided with a switching TFT and a current controlling TFT further is provided with an element that has a rectifying characteristic. The switching TFT charges a capacitor in accordance with a data signal and the current controlling TFT controls light emission of an organic light emitting element in accordance with voltage supplied from the capacitor. Reverse bias is readily applied to the organic light emitting element by applying voltage to the element that has a rectifying characteristic in the forward direction from an alternating current source.

Abstract: A light emitting device is provided, in which a change of luminance of an OLED is suppressed and a desired color display can be stably performed even if an organic light emitting layer is somewhat deteriorated or an environmental temperature is varied. Separately from a pixel portion for displaying an image, a pixel portion for measuring a driving current of the OLED is provided in the light emitting device. The driving current is measured in the pixel portion for measuring the driving current of the OLED, and a value of the voltage supplied to the above two pixel portions from a variable power supply is corrected such that the measured driving current has a reference value. With the above-described structure, a reduction of the luminance accompanied with the deterioration of the organic light emitting layer can be suppressed. As a result, a clear image can be displayed.

Abstract: To provide an electronic device capable of bright image display. A pixel is structured such that a switching TFT and a current controlling TFT are formed on a substrate and an EL element is electrically connected to the current controlling TFT. A gate capacitor formed between a gate electrode of the current controlling TFT and an LDD region thereof holds a voltage applied to the gate electrode, and hence a capacitor (condenser) is not particularly necessary in the pixel, thereby making the effective light emission area of the pixel large.

Abstract: The present invention provides an inexpensive light emitting device and an inexpensive electric appliance. By reducing the number of photolithography steps in the fabrication of TFTs, the yield of the light emitting devices can be enhanced and the manufacturing period can be shortened. The present invention is substantially characterized in that a gate electrode is formed of a conductive film made of a plurality of layers and the concentration of impurity regions formed in the inside of an active layer can be adjusted by making use of the selection ratio at the time of etching these layers.

Abstract: There is provided a light emitting device including a TFT having a high driving capacity (on current) and high reliability in a driver circuit and a TFT in which an off current is reduced in a pixel portion. In manufacturing the TFTs, after the TFT having an LDD region is formed, a part of a gate electrode is etched to form the TFT having a GOLD region. Thus, the TFTs having required functions can be easily formed in the driver circuit and the pixel portion, respectively, on the same substrate.

Abstract: To provide a self-luminous device capable of clear, multi-gray scale, color display and an electric machine provided with the same. Gray scale display is attained by a time division driving method in which an EL element (109) provided in a pixel (104) is controlled to emit light or not to emit light by means of time, thereby avoiding being affected by fluctuation in characteristic in current controlling TFTs (108).

Abstract: To provide an active matrix electronic device capable of performing clear color gray-scale display. The electronic device is characterized in that a plurality of pixels composing a pixel portion is surrounded by a source signal line, a first gate signal line, a second gate signal line, and a power supply line, and that the plurality of pixels have a switching TFT, an EL driving TFT, an eliminating TFT, and an EL element, respectively.

Abstract: A method of driving an EL display device in which pseudo contours are difficult to be seen is provided. A method of driving an EL display device in which a plurality of pixels, each having a first TFT, a second TFT, a third TFT, and an organic EL element, are formed has the following: n+m display periods (where n and m are both natural numbers) appear in one frame period; the n+m display periods each correspond to one bit of a digital video signal among n bits of the digital video signal; a plurality of display periods, among the n+m display periods, correspond to the same bit of the digital video signal; and display periods corresponding to other bits of the digital video signal, among the n+m display periods, appear during the plurality of display periods.