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: 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: 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.

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: 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 brightness of a light emitting element varies when changes in ambient temperature or changes with time occur. In view of this, the invention provides a display device where the influence of variations in the current value of the light emitting element due to changes in ambient temperature and changes with time can be suppressed. The display device of the invention includes a monitoring element that is driven with a constant current, and a voltage applied to the monitoring element is detected and inputted to a light emitting element. In other words, the monitoring element is driven with a low current, and a voltage applied to the monitoring element is inputted to the light emitting element such that the light emitting element is driven with a constant current.

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: If a potential of a gate electrode of a driving transistor varies after a gray scale signal is inputted into each pixel, a current value of a current supplied to a light emitting element varies so that accurate gray scale display cannot be obtained. In particular, in the case of performing black display, current may flow, which makes clear black display difficult. Accordingly, the invention provides a light emitting device capable of performing accurate gray scale display, and a driving method thereof. According to the invention, a signal for display is inputted plural times within a predetermined timing period, or a writing operation period is lengthened. Consequently, the gate voltage of the transistor is determined after the anode potential of the light emitting element is stabilized, and therefore accurate gray scale display can be performed.

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.

Abstract: When adopting a time division gray scale, a pseudo contour occurs. The invention provides a new driver circuit and driving method of an active display device, which can reduce the occurrence of a pseudo contour by using an interlace method. The invention provides an active display device adopting an interlace method, where pixels of odd-numbered rows and odd-numbered columns and pixels of even-numbered rows and even-numbered columns are displayed during an odd-numbered frame period, and pixels of odd-numbered rows and even-numbered columns and pixels of even-numbered rows and odd-numbered columns are displayed during an even-numbered frame period. As a result, the occurrence of a pseudo contour can be reduced without increasing the frame frequency.

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: It is an object to provide a driving method of a semiconductor display device by which generation of pseudo contour can be suppressed while suppressing the operating frequency of a driver circuit. It is also an object to provide a driving method of a semiconductor display device by which generation of pseudo contour can be suppressed while suppressing decrease in image quality. One mode of the invention is a driving method of a semiconductor display device, wherein a set of a plurality of subframe periods is provided in one frame period and the set of the plurality of subframe periods is inverted at some point to be provided.

Abstract: A light emitting element has a property that a resistance value (internal resistance value) thereof changes according to the ambient temperature. Specifically, assuming that the room temperature is a normal temperature, when the ambient temperature becomes higher than the normal temperature, a resistance value is decreased, and when the ambient temperature becomes lower than the normal temperature, a resistance value is increased. Therefore, when the ambient temperature changes or degradation is caused with time due to the aforementioned property of the light emitting element, luminance varies. The invention provides a display device where an effect of current fluctuation of a light emitting element, which is caused by the change in ambient temperature and degradation with time, is suppressed. The display device comprises a monitoring element, to which a current is supplied from a current source. A voltage applied to the monitoring element is applied to a light emitting element.

Abstract: A display device having a pixel configuration in which the aperture ratio is not decreased, and a driving method of a display device in which the duty ratio and the reliability of a light emitting element are increased. According to the invention, a signal line for inputting an analog signal, a first switch controlled by a first scan line, a second switch controlled by a second scan line, and a light emitting element connected to the second switch are included, wherein the first switch and the second switch are selected and an analog signal is inputted in a first period of one gate selection period, the first switch is selected and a reference signal is inputted from the signal line in a second period of the one gate selection period, and the light emitting element emits light by the analog signal and the reference signal.

Abstract: The luminance of light emitting elements varies when the characteristics thereof change due to changes in environment temperature and changes with time. It is an object of the present invention to suppress the effect of the change in current value of a light emitting element due to the changes of environment temperature and changes with time. The invention provides a display device provided with a compensation function for the changes in environment temperature and a compensation function for the change with time. The display device of the invention includes a light emitting element, a driving transistor connected to the light emitting element, and a monitoring light emitting element. By using this monitoring light emitting element, an effect of the change of current value of the light emitting element due to the change of environment temperature and change with time can be suppressed.

Abstract: The invention provides a semiconductor display device with less generation of a pseudo contour while the drive frequency of a driver circuit is suppressed. Furthermore, the invention provides a semiconductor display device with less generation of a pseudo contour while the decrease in image quality is suppressed. A semiconductor display device comprises a table storing data for determining a relationship between the gray scale level of a video signal and a subframe period for light emission in the plurality of subframe periods, a controller for changing a video signal in accordance with the data and outputting, and a panel whose pixel gray scale level is controlled in accordance with the outputted video signal. The number and the length of the plural subframe periods for each gray scale level of 2 or more are determined in accordance with a subframe ratio RSF which is calculated in accordance with a sharing ratio Rsh determined by the frame frequency.

Abstract: The inventors found out that in the case of performing a low gray scale display in which a very small amount of current is supplied to a light emitting element, variations in threshold voltages of driving transistors become notable since the gate-source voltage is low. In view of this, the invention provides a display device in which variations in the threshold voltages of the driving transistors are reduced even in the low gray scale display, and a driving method thereof. According to the invention, a gate-source voltage of the driving transistor is set higher in the low gray scale display than that in the high gray scale display. As one mode to achieve this, different power source lines are provided for the low gray scale display and the high gray scale display and their potentials are set to be different.

Abstract: A display device where the power consumption of a display panel can be reduced by controlling a display time rate. The display device includes a gray scale control circuit for controlling the display time rate of a pixel of a display means based on an output of a display time rate table that outputs a gray scale control signal for reducing the display time rate of a pixel when the average gray scale of a video signal of one frame obtained by an one frame average gray scale calculator exceeds a certain value. A display time of a pixel is controlled by erasing a video signal written to a pixel of the display means based on an output signal of the display time rate table. When an image with a high average gray scale is displayed, the luminance of the entire screen increases and power consumption increases. However, power consumption can be suppressed to a certain value by decreasing the display time rate when the average gray scale of a video signal of one frame exceeds a certain value.

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 time division gray scale display device with a pseudo contour effectively suppressed, and a driving method thereof. A display device wherein one frame period of a digital video signal includes a plurality of subframes having different powers, comprising a pixel matrix portion, a signal line driver circuit, a scan line driver circuit, a frame frequency converter circuit for converting the frame frequency of an inputted digital video signal in frame, a time division gray scale signal generation circuit for converting the digital video signal in frame into a gray scale signal in subframe, and a controller for supplying a time division gray scale signal to the pixel matrix portion by controlling the time division gray scale signal generation circuit, the signal line driver circuit, and the scan line driver circuit. The frame frequency converter circuit outputs a digital video signal having a frame frequency of 75 Hz or more.