Liquid crystal display device, driving method of the same, and electronic device including the same

Abstract

It is an object to suppress deterioration of characteristics of a transistor in a driver circuit. A first switch for controlling whether to set a potential state of an output signal by being turned on and off in accordance with the first input signal, and a second switch for controlling whether to set a potential state of an output signal by being turned on and off in accordance with the second input signal are included. A first wiring and a second wiring are brought into electrical continuity by turning on and off of the first switch or the second switch.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a semiconductor device, a display device, a liquid crystal display device, a method for driving these devices, and a method for manufacturing these devices. The present invention particularly relates to a semiconductor device, a display device, and a liquid crystal display device which include driver circuits formed over the same substrates as pixel portions, and a method for driving these devices. Further, the present invention relates to an electronic device including the semiconductor device, the display device, or the liquid crystal display device.[0003]2. Description of the Related Art[0004]In recent years, with the increase of large display devices such as liquid crystal televisions, display devices have been actively developed. In particular, a technique for forming a driver circuit such as a gate driver over the same substrate as a pixel portion by using transistors including a n...

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Benefits of technology

[0034]Further, there is no particular limitation on the kind of substrate for forming a transistor and a transistor can be formed using a variety of kinds of substrate. As an example of the substrate, a semiconductor substrate, a single crystal substrate (e.g., a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate including a stainless steel foil, a tungsten substrate, a substrate including a tungsten foil, a flexible substrate, an attachment film, paper including a fibrous material, a base material film, or the like can be given. As an example of a glass substrate, a barium borosilicate glass substrate, an aluminoborosilicate glass substrate, soda lime glass substrate, or the like can be given. For a flexible substrate, a flexible synthetic resin such as plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyether sulfone (PES), or acrylic can be used, for example. Examples of an attachment film are an attachment film formed using polypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, and the like. Examples of a base film are a base film formed using polyester, polyamide, polyimide, inorganic vapor deposition film, paper, and the like. Specifically, when a transistor is formed using a semiconductor substrate, a single crystal substrate, an SOI substrate, or the like, a transistor with few variations in characteristics, size, shape, or the like, high current supply capability, and a small size can be formed. By forming a circuit using such transistors, power consumption of the circuit can be reduced or the circuit can be highly integrated.

[0035]Note that the transistor may be formed using one substrate, and then, the transistor may be transferred to another substrate. Example of a substrate to which a transistor is transferred are, in addition to the above-described substrate over which the transistor can be formed, a paper substrate, a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including a natural fiber (e.g., silk, cotton, or hemp), a synthetic fiber (e.g., nylon, polyurethane, or polyester), a regenerated fiber (e.g., acetate, cupra, rayon, or regenerated polyester), or the like), a leather substrate, a rubber substrate, and the like. When such a substrate is used, improvement in electrical characteristics of a transistor or reduction in power consumption of the transistor can be achieved. Further, improvement in reliability, improvement in heat resistance, reduction in weight, or reduction in thickness of a device which includes the transistor can be achieved.

[0036]Note that all the circuits which are necessary to realize a desired function can be formed using one substrate (e.g., a glass substrate, a plastic substrate, a single crystal substrate, or an SOI substrate). In this manner, cost can be reduced by reduction in the number of component parts or reliability can be improved by reduction in the number of connection to circuit components.

[0037]In addition, not all the circuits which are necessary to realize the predetermined function are needed to be formed using one substrate. That is, part of the circuits which are necessary to realize the predetermined function may be formed using one substrate and another part of the circuits which are necessary to realize the predetermined function may be formed using another substrate. For example, part of the circuits which are necessary to realize the predetermined function may be formed over a glass substrate and another part of the circuits which are necessary to realize the predetermined function may be formed using a single crystal substrate. Then, the single crystal substrate provided with the another part of the circuits which are necessary to realize the predetermined function may be connected to a glass substrate by COG (chip on glass) so that the single crystal substrate provided with the circuit (also referred to as an IC chip) can be provided for the glass substrate. Alternatively, the IC chip can be connected to the glass substrate by using TAB (tape automated bonding), COF (chip on film), SMT (surface mount technology), a printed substrate, or the like. When part of the circuits is formed over a substrate where a pixel portion is formed in this manner, cost can be reduced by reduction in the number of component parts or reliability can be improved by reduction in the number of connections between circuit components. Specifically, a circuit in a portion where a driving voltage is high, a circuit in a portion where a driving frequency is high, or the like consumes much power in many cases. Therefore, such a circuit is formed over a substrate (e.g., a single crystal substrate) which is different from a substrate over which the pixel portion is formed, so that an IC chip is formed. By the use of this IC chip, increase in power consumption can be prevented.

[0060]According to one embodiment of the present invention, deterioration in characteristics of a transistor can be suppressed. Alternatively, according to one embodiment of the present invention, the channel width of a transistor can be reduced. Particularly, suppression of deterioration in characteristics of a pull-up transistor or reduction in channel width of a pull-up transistor can be achieved. Alternatively, according to one embodiment of the present invention, a layout area can be reduced. Alternatively, according to one embodiment of the present invention, the size of a frame of a display device can be reduced. Alternatively, according to one embodiment of the present invention, a high-definition display device can be obtained. Alternatively, according to one embodiment of the present invention, an yield can be increased. Alternatively, according to one embodiment of the present invention, manufacturing costs can be reduced. Alternatively, according to one embodiment of the present invention, power consumption can be reduced. Alternatively, according to one embodiment of the present invention, current supply capability of an external circuit can be reduced. Alternatively, according to one embodiment of the present invention, the size of an external circuit or the size of a display device including the external circuit can be reduced.

Problems solved by technology

Alternatively, in some cases when the channel width of a transistor is large, a gate and a source or a drain of the transistor are likely to be short-circuited.

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