Abstract: A semiconductor display device that operates normally at a room temperature may not operate normally at a low temperature. Meanwhile, in semiconductor display devices with the same circuit configuration and the same driving method, the higher the operating frequency is, the better the display quality is. Thus, a semiconductor display device the operating frequency of which is set on the basis of a room temperature may not operate normally at a low temperature. According to the invention, the temperature and the operating state of a semiconductor display device are measured to vary the operating frequency in accordance with the measurement result. More specifically, the operating frequency is decreased at a low temperature to obtain normal operation, while the operating frequency is increased at a room temperature and a high temperature to improve the display quality.

Abstract: In this manner, even when a patterning precision for forming a semiconductor element and a wiring finer is improved, high definition of a display device having a light emitting element is not expected since the intervals between the apertures of the metal mask cannot be narrow. In view of the aforementioned problem, according to the invention, element forming regions of the same color are disposed diagonally and a pixel portion has a structure that a region for forming an element are shared by a plurality of pixels. A specific pixel structure of the invention is that element forming regions of a first color, a second color, and a third color are each disposed diagonally and three or more element forming regions are shared by each pixel.

Abstract: A method of electrically inspecting semiconductor display devices, which is capable of inspecting whether a signal is normally input to the pixels and whether an electric charge is normally held by the holding capacitors without using the video signal line as a passage for reading the electric charge and without separately providing an inspection-dedicated circuit. Power source lines which are used as passages for supplying the power source voltage are used as passages for reading the electric charge. Namely, the power source lines that can be connected to the signal lines are used as passages for inputting an inspection signal to the holding capacitors in the pixels and for reading the electric charge from the holding capacitors in the pixels.

Abstract: The invention provides a display device with which a user's view is not completely interrupted by an image that is displayed artificially and of which optical system is easy in design. In addition, the invention provides a telecommunication system capable of providing additional visual information by the use of the display device. According to the invention, an image can be displayed while securing a user's view by using a light emitting device that can display an image and transmit light as a display device. Specifically, a pair of electrodes included in a light emitting element is formed to transmit light so as to transmit the outside light. By crossing a visual axis of a user and a pixel portion of the light emitting device, both of the outside light and the light emitted from the pixel portion can enter into the eyeballs of a user.

Abstract: A method of electrically inspecting semiconductor display devices, which is capable of inspecting whether a signal is normally input to the pixels and whether an electric charge is normally held by the holding capacitors without using the video signal line as a passage for reading the electric charge and without separately providing an inspection-dedicated circuit. Power source lines which are used as passages for supplying the power source voltage are used as passages for reading the electric charge. Namely, the power source lines that can be connected to the signal lines are used as passages for inputting an inspection signal to the holding capacitors in the pixels and for reading the electric charge from the holding capacitors in the pixels.

Abstract: A photodetector of the invention is characterized by having a plurality of detector elements that are arranged over a light-transparent substrate and are connected in parallel. A foldable portable communication tool having two display portions of the invention is characterized by including one photodetector which includes a plurality of detector elements connected in parallel.

Abstract: A driving method of a light emitting device, in which when an N-type driving TFT is connected to an anode of a light emitting element or a P-type driving TFT is connected to a cathode thereof, the driving TFT operates in a saturation region and an image can be displayed with a desired gray scale level depending on a video signal. In addition, a light emitting device adopting the driving method is provided. According to the invention, when a potential having image data is supplied to a gate of a driving TFT depending on a video signal, a reverse bias voltage is applied to the driving TFT and a light emitting element which are connected in series with each other. Meanwhile, when a pixel displays an image depending on the video signal, a forward bias voltage is applied to the driving TFT and the light emitting element.

Abstract: A compact and lightweight display device having an image pickup function and a two-way communication system which can shoot an image of a user as an object and display an image at the same time without degrading image quality by disposing a semi-transmitting mirror or the like which blocks an image on the display screen (display plane). The display device having the image pickup function includes a display panel capable of transmitting visible light at least and arranging display elements which can be controlled by voltage or current, and an image pickup device disposed around the display panel. The image pickup device is input with data of an image of a user or the like by a reflector, or equipped with a fiberscope bundling optical fibers.

Abstract: In the respect of an electrical characteristic of a transistor, a channel size W/L of a transistor is preferably designed small in order to decrease an effect of a variation in threshold voltage, while the channel size W/L is preferably designed large in order to widen a saturation region as an operation region of the transistor in the respect of characteristic of a light emitting element. Thus, decreasing an effect of a variation in threshold voltage and widening a saturation region in order not to reduce luminance due to a degradation of the light emitting element are in the relation of trade-off. According to the invention, a current capacity of a driving transistor is increased so as to operate in a wide saturation region. A lighting period control circuit is provided in each pixel for changing a lighting period of each pixel separately.

Abstract: A two-way communication device having a display device of novel structure and an image pickup device is provided. More particularly, a two-way communication system having a display device and an image pickup device is provided. The display device having an image pickup function includes an image pickup unit and a display panel in which light emitting elements which can transmit visible light at least and be controlled by voltage or current are arranged. A compact and lightweight device can be achieved without using a complicated optical system or an optical system having a long light path, whereby two parties can communicate while catching each other's eyes.

Abstract: By operating a driving TFT in a saturation region, luminance is not easily reduced when an EL element is degraded. However, such problems occur as a high voltage, high power consumption, and heat generation. In the case of operating a driving TFT in a saturation region, luminance varies due to a variation of driving TFTs. In view of the aforementioned problems, a high current capacity TFT is used in the high gray-scale and a low current capacity TFT is used in the low gray-scale. The high current capacity TFT can supply a large current with a lower Vgs, therefore, it does not easily operate in a linear region even when Vds is lowered. Thus, a luminance is not reduced easily even when an EL element is degraded, and an operation at a low voltage is realized. The low current capacity TFT supplies current when high Vgs is applied. With high Vgs, an effect of variation in characteristics of TFTs, especially in Vth can be ameliorated.

Abstract: A latch circuit is disposed to an output terminal of the respective stages of a shift register circuit, when a pulse is shifted to a stage to which an output is wanted to be outputted, a latch pulse is inputted and held there until a subsequent pulse is inputted, when the pulse is shifted to a stage to which an output is wanted to be outputted in the next time, a latch pulse is again inputted, and thereby an output stage is switched. Thus, a period to be selected and a stage to be selected can be arbitrary selected by changing a latch pulse without changing a clock frequency.

Abstract: For an inspection of a display device which incorporates a driver circuit around pixels, a start pulse and a clock pulse are required to be inputted as inspection signals. The more complex the driver circuit is, the more complexity the start pulse and the clock pulse tend to have, which will increase the manufacturing cost of inspection signals. In addition, since a clock generator is required, cost of an inspection device is increased. Furthermore, it will lead to a longer inspection time. By setting all the power supplies for the driver circuit at a desired potential, a desired potential is outputted regardless of an input signal.

Abstract: It is an object of the present invention to provide a display device that is able to display a three-dimensional image without reducing resolution in displaying a two-dimensional image to half, and prevent the device itself from being bulky. This display device is a display device that has a light-emitting device having a plurality of pixels and an optical system at one side of the light-emitting device, where the light-emitting element has two electrodes that both have translucency, light is shielded by the first shield means and light is shielded by the second shield means, and the optical system makes light emitted from one of two adjacent pixels of the plurality of pixels incident into a let eye of a viewer and makes light emitted from the other incident into a right eye of the viewer by controlling a traveling direction of light emitted from the plurality of pixels.

Abstract: A method of electrically inspecting semiconductor display devices, which is capable of inspecting whether a signal is normally input to the pixels and whether an electric charge is normally held by the holding capacitors without using the video signal line as a passage for reading the electric charge and without separately providing an inspection-dedicated circuit.

Abstract: A conventional setting voltage was a value with an estimated margin of a characteristic change of a light, emitting element. Therefore, a voltage between the source and drain of a driver transistor Vds had to be set high (Vds≧Vgs−VTh+a). This caused high heat generation and power consumption, because a voltage applied to the light emitting element. The invention is characterized by,feedbacking a change in a current value in accordance with the deterioration of a light emitting element and a power source voltage controller which modifies a setting voltage. Namely, according to the invention, the setting voltage is to be set in the vicinity of the boundary (critical part) between ,a saturation region and a linear region,. and a voltage margin for the. deterioration is not required particularly for an initial setting voltage.

Abstract: The reliability of an EL element is enhanced while the increase of the electric power consumption is suppressed. It becomes possible that in a SES drive, the reverse bias is applied to the EL element driven at a constant electric current. Moreover, the application of the reverse bias is performed by varying only the counter electrode, and thus withstand voltage of TFT and the increase of the electric power consumption due to the increase of voltage of the gate signal line drive circuit, which becomes a problem when changing greatly the electric current supplying line, can be suppressed. Furthermore, the reduction of the electric power consumption can also be achieved while the enhancement of the reliability is secured by making the reverse bias smaller than the forward bias.

Abstract: A light emitting device that achieves long life, and which is capable of performing high duty drive, by suppressing initial light emitting element deterioration is provided. Reverse bias application to an EL element (109) is performed one row at a time by forming a reverse bias electric power source line (112) and a reverse bias TFT (108). Reverse bias application can therefore be performed in synchronous with operations for write-in of an image signal, light emission, erasure, and the like. Reverse bias application therefore becomes possible while maintaining a duty equivalent to that of a conventional driving method.