JP6298491B2 - Display device - Google Patents

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JP6298491B2
JP6298491B2 JP2016109059A JP2016109059A JP6298491B2 JP 6298491 B2 JP6298491 B2 JP 6298491B2 JP 2016109059 A JP2016109059 A JP 2016109059A JP 2016109059 A JP2016109059 A JP 2016109059A JP 6298491 B2 JP6298491 B2 JP 6298491B2
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transistor
electrode
wiring
electrically connected
pixel
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JP2016212945A (en
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敦司 梅崎
敦司 梅崎
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株式会社半導体エネルギー研究所
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The present invention relates to a display device having a circuit formed using a transistor. In particular, the present invention relates to a display device using an electro-optic element such as liquid crystal or a light emitting element as a display medium, and a driving method thereof.

In recent years, display devices have been actively developed due to an increase in large display devices such as liquid crystal televisions. In particular, a technique for integrally forming a driver circuit (hereinafter also referred to as an internal circuit) including a pixel circuit and a shift register using a transistor formed of an amorphous semiconductor (hereinafter also referred to as amorphous silicon) on an insulating substrate is described. In order to greatly contribute to the reduction of power consumption and cost, development is being actively promoted. An internal circuit formed on the insulator is connected to a controller IC or the like (hereinafter also referred to as an external circuit) via an FPC or the like, and its operation is controlled.

Among the internal circuits shown above, a shift register using a transistor formed of an amorphous semiconductor (hereinafter also referred to as an amorphous silicon transistor) has been devised.
A structure of a flip-flop included in a conventional shift register is illustrated in FIG. 124A (Patent Document 1). The flip-flop in FIG. 124A includes a transistor 11, a transistor 12,
A transistor 13, a transistor 14, a transistor 15 and a transistor 17;
The signal line 21, the signal line 22, the wiring 23, the signal line 24, the power supply line 25, and the power supply line 26 are connected. A start signal, a reset signal, a clock signal, a power supply potential VDD, and a power supply potential VSS are input to the signal line 21, the signal line 22, the signal line 24, the power supply line 25, and the power supply line 26, respectively. The operation period of the flip-flop in FIG. 124A is divided into a set period, a selection period, a reset period, and a non-selection period as shown in the timing chart of FIG. Selection period.

Here, the transistor 12 and the transistor 16 are on in the non-selection period. Therefore, since amorphous silicon is used for the semiconductor layers of the transistors 12 and 16, the threshold voltage (Vth) varies due to deterioration or the like. More specifically, the threshold voltage increases. That is, the conventional shift register cannot be turned on because the threshold voltages of the transistors 12 and 16 are increased, so that VSS cannot be supplied to the node 41 and the wiring 23 and malfunction occurs.

In order to solve this problem, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3 devise shift registers that can suppress the shift of the threshold voltage of the transistor 12. In Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3, a new transistor (referred to as a first transistor) is arranged in parallel with a transistor 12 (referred to as a second transistor). By inputting inverted signals to the gate electrode of the first transistor and the gate electrode of the second transistor, the threshold voltage shift of the first transistor and the second transistor is suppressed.

Further, Non-Patent Document 4 devises a shift register that can suppress the shift of the threshold voltage of the transistor 16 as well as the transistor 12. In Non-Patent Document 4, a new transistor (referred to as a first transistor) is arranged in parallel with a transistor 12 (referred to as a second transistor), and another new transistor (referred to as a third transistor) is provided as a transistor. 16 (referred to as a fourth transistor) is arranged in parallel. In the non-selection period, inverted signals are input to the gate electrode of the first transistor and the gate electrode of the second transistor, respectively, and inverted to the gate electrode of the third transistor and the gate electrode of the fourth transistor, respectively. By inputting a signal, a shift in threshold voltage of the first transistor, the second transistor, the third transistor, and the fourth transistor is suppressed.

Further, in Non-Patent Document 5, the shift of the threshold voltage of the transistor 12 is suppressed by applying an AC pulse to the gate electrode of the transistor 12.

Note that the display devices of Non-Patent Document 6 and Non-Patent Document 7 use a shift register formed of an amorphous silicon transistor as a scanning line driving circuit, and further video from one signal line to R, G, and B subpixels. By inputting signals, the number of signal lines is reduced to 1/3. Thus, the display devices of Non-Patent Document 6 and Non-Patent Document 7 reduce the number of connections between the display panel and the driver IC.

JP 2004-157508 A

Soo Young Yoon, et al. , "Highly Stable Integrated Gate Driver A-Si TFT with Dual Pull-down STRUCTURE", SICIETY FOR INFORMATION DISPLAY. 348-351 Binn Kim, et al. , "A-Si Gate Driver Integration with Time Shared Data Driving", Proceedings of The 12th International Display Workshops in Conjunction. 1073-1076 Mindoo Chun, et al. , "Integrated Gate Driver Using Highly Stable a-Si TFT's", Proceedings of The 12th International Display Workshops in junction with Asp. 1077-1080 Chun-Ching, et al. , "Integrated Gate Driver Using a-Si TFT", Processeds of The 12th International Display Workshops in junction with Asia Disp. 5, 1023-1026 Yong Ho Jang, et al. , "A-Si TFT Integrated Gate Driver with AC-Driving Single Pull-Down Structure X, SOCIETY FOR INFORMATION DISPLAY TECHNO TECHNO TECHNO TECHN 208-211 Jin Young Choi, et al. , "A Compact and Cost-Efficient TFT-LCD through the Triple-Gate Pixel Structure II XOPIC TECHN TECHN TECHNO TECHN TECHN 274-276 Yong Soon Lee, et al. , "Advanced TFT-LCD Data Line Reduction Method", SOCIETY FOR INFORMATION DISPLAY 2006 INTERNIONAL SYMPOSIUM DIGITAL OF TECHNICAL PAPERS, X. 1083-1086

According to the conventional technique, the shift of the threshold voltage of the transistor is suppressed by applying an AC pulse to the gate of the transistor that is easily deteriorated. However, when amorphous silicon is used as the semiconductor layer of the transistor, it is a problem that the transistor constituting the circuit that generates the AC pulse also causes a threshold voltage shift.
In addition, it has been proposed to reduce the number of contact points between the display panel and the driver IC by reducing the number of signal lines to 1/3 (Non-Patent Document 6 and Non-Patent Document 7). There is a need to further reduce the number of IC contacts.

That is, as a problem that cannot be solved by the conventional technique, a circuit technique that suppresses the fluctuation of the threshold voltage of the transistor remains as a problem. A technique for reducing the number of contact points of a driver IC mounted on a display panel remains as a problem. Lowering power consumption of display devices remains a problem. There remains a problem of enlargement or high definition of the display device.

An object of the invention disclosed in this specification is to provide an industrially useful technique by solving one or more of these problems.

The display device according to the present invention inputs a signal to the gate electrode of a transistor that is easily deteriorated through the turned-on transistor, thereby shifting the threshold voltage of the transistor that is easily deteriorated and the threshold voltage of the turned-on transistor. This suppresses the shift. That is,
The present invention includes a configuration in which an AC pulse is applied to a gate electrode of a transistor that easily deteriorates through a transistor to which a high potential (VDD) is applied to the gate electrode (or through an element having a resistance component). .

The switch described in this specification can be used in various forms. Examples include electrical switches and mechanical switches. That is, it is only necessary to be able to control the current flow, and is not limited to a specific one. For example, as a switch, a transistor (for example,
Bipolar transistor, MOS transistor, etc.), diode (for example, PN diode, PIN diode, Schottky diode, MIM (Metal Insult)
orMetal) diode, MIS (Metal Insulator Semiconductor)
uctor) diodes, diode-connected transistors, etc.), thyristors, etc. can be used. Alternatively, a logic circuit combining these can be used as a switch.

In the case where a transistor is used as a switch, the transistor operates as a mere switch, and thus the polarity (conductivity type) of the transistor is not particularly limited. However, when it is desired to suppress off-state current, it is desirable to use a transistor having a polarity with smaller off-state current. As a transistor with low off-state current, a transistor having an LDD region, a transistor having a multi-gate structure, and the like can be given. Alternatively, in the case where the transistor operates as a switch with a source terminal potential close to a low potential power source (VSS, GND, 0 V, or the like), an N-channel transistor is preferably used. On the other hand, the potential of the source terminal is
When operating in a state close to a high-potential side power supply (VDD or the like), it is desirable to use a P-channel transistor. This is because when the N-channel transistor operates with the source terminal close to the low-potential side power supply, and the P-channel transistor operates with the source terminal close to the high-potential side power supply, the absolute value of the gate-source voltage is Since it can be increased, the switching characteristics are improved. Moreover, since the source follower operation is rarely performed, the output voltage is rarely reduced.

A CMOS switch may be used as a switch by using both an N-channel transistor and a P-channel transistor. When a CMOS switch is used, a current flows when one of the P-channel transistor and the N-channel transistor is turned on, so that the switch can easily function as a switch. For example, the voltage can be appropriately output regardless of whether the voltage of the input signal to the switch is high or low. Furthermore, since the voltage amplitude value of the signal for turning on / off the switch can be reduced, the power consumption can be reduced.

When a transistor is used as a switch, the switch includes an input terminal (one of a source terminal or a drain terminal), an output terminal (the other of the source terminal or the drain terminal), and a terminal (gate terminal) that controls conduction. Yes. On the other hand, when a diode is used as the switch, the switch may not have a terminal for controlling conduction. Therefore, the use of a diode as a switch rather than a transistor can reduce the wiring for controlling the terminal.

In this specification, when “A and B are connected” is explicitly described, A and B are electrically connected and A and B are functionally connected. And the case where A and B are directly connected. Here, A and B are objects (for example, devices, elements, circuits, wirings, electrodes, terminals, conductive films, layers, etc.). Therefore, the configuration disclosed in this specification is not limited to a predetermined connection relationship, for example, the connection relationship illustrated in the drawing or text, and includes other than the connection relationship illustrated in the drawing or text.

For example, when A and B are electrically connected, an element (for example, a switch, a transistor, a capacitor, an inductor, a resistance element, a diode, or the like) that enables electrical connection between A and B is provided. 1 or more may be arranged between A and B. Alternatively, when A and B are functionally connected, a circuit (for example, a logic circuit (an inverter, a NAND circuit, a NOR circuit, etc.), a signal conversion circuit that enables functional connection between A and B (DA conversion circuit, AD conversion circuit, gamma correction circuit, etc.), potential level conversion circuit (power supply circuit (boost circuit,
Step-down circuit), level shifter circuit that changes signal potential level), voltage source, current source,
Switching circuit, amplifier circuit (circuit that can increase signal amplitude or current, etc., operational amplifier,
One or more differential amplifier circuits, source follower circuits, buffer circuits, etc.), signal generation circuits, memory circuits, control circuits, etc.) may be arranged between A and B. Alternatively, when A and B are directly connected, A and B without interposing other elements or other circuits between A and B.
And may be directly connected.

When it is explicitly described that “A and B are directly connected”, when A and B are directly connected (that is, another element or other circuit is connected between A and B). And A and B are electrically connected (that is, A and B are connected with another element or circuit sandwiched between them). Case).

When it is explicitly described that “A and B are electrically connected”, when A and B are electrically connected (that is, another element or When connected with another circuit) and when A and B are functionally connected (that is, functionally connected with another circuit between A and B) Case) and a case where A and B are directly connected (that is, a case where another element or another circuit is not connected between A and B). That is, when it is explicitly described that it is electrically connected, it is the same as when it is explicitly only described that it is connected.

A display element, a display device that includes a display element, a light-emitting element, and a light-emitting device that includes a light-emitting element can have various modes or have various elements. For example, as a display element, a display device, a light-emitting element, or a light-emitting device, an EL element (an organic EL element or an inorganic EL element) can be used.
Element or EL element including organic and inorganic substances), electron emission element, liquid crystal element, electronic ink, electrophoretic element, grating light valve (GLV), plasma display (PDP)
In addition, a display medium whose contrast, luminance, reflectance, transmittance, or the like is changed by an electromagnetic action, such as a digital micromirror device (DMD), a piezoelectric ceramic display, or a carbon nanotube, can be used. As a display device using an EL element, E
As a display device using an L display or an electron-emitting device, a field emission display (FED) or a SED type flat display (SED: Surface-cond)
Liquid crystal displays (transmission type liquid crystal display, transflective type liquid crystal display, reflective type liquid crystal display, direct view type liquid crystal display, projection type liquid crystal display), electronic ink and electrophoresis as display devices using liquid crystal elements such as action Electron-emitter Display There is electronic paper as a display device using an element.

Various types of transistors can be used as the transistor described in this specification. Thus, there is no limitation on the type of transistor used. For example, a thin film transistor (TFT) including a non-single-crystal semiconductor film typified by amorphous silicon, polycrystalline silicon, microcrystalline (also referred to as semi-amorphous) silicon, or the like can be used. When using TFT, there are various advantages. For example, since it can be manufactured at a temperature lower than that of single crystal silicon, the manufacturing cost can be reduced and the manufacturing apparatus can be enlarged. Since the manufacturing apparatus can be enlarged, it can be manufactured on a large substrate. Therefore, since a large number of display devices can be manufactured at the same time, it can be manufactured at low cost. Furthermore, since the manufacturing temperature is low, a substrate with low heat resistance can be used. Therefore, a transistor can be manufactured on a transparent substrate. Then, light transmission through the display element can be controlled using a transistor over a transparent substrate. Alternatively, since the thickness of the transistor is small, part of the film included in the transistor can transmit light. Therefore, the aperture ratio can be improved.

By using a catalyst (such as nickel) when manufacturing polycrystalline silicon, it is possible to further improve crystallinity and to manufacture a transistor with good electrical characteristics. as a result,
A gate driver circuit (scanning line driving circuit), a source driver circuit (signal line driving circuit), and a signal processing circuit (signal generation circuit, gamma correction circuit, DA conversion circuit, etc.) can be integrally formed on the substrate.

By using a catalyst (such as nickel) when manufacturing microcrystalline silicon, it is possible to further improve crystallinity and to manufacture a transistor with good electrical characteristics. At this time,
Crystallinity can be improved simply by applying heat treatment without using a laser. As a result, a part of the gate driver circuit (scanning line driver circuit) and the source driver circuit (analog switch or the like) can be integrally formed on the substrate. Further, when a laser is not used for crystallization, unevenness in crystallinity of silicon can be suppressed. Therefore, a beautiful image can be displayed.

However, it is possible to produce polycrystalline silicon or microcrystalline silicon without using a catalyst (such as nickel).

Alternatively, a transistor can be formed using a semiconductor substrate, an SOI substrate, or the like. In that case, a MOS transistor, a junction transistor, a bipolar transistor, or the like can be used as the transistor described in this specification. Accordingly, a transistor with small variations in characteristics, size, shape, and the like, high current supply capability, and small size can be manufactured. When these transistors are used, a circuit with low power consumption can be formed, or high integration can be achieved.

Alternatively, a transistor having a compound semiconductor or an oxide semiconductor such as ZnO, a-InGaZnO, SiGe, GaAs, IZO, ITO, or SnO, or a thin film transistor in which these compound semiconductor or oxide semiconductor is thinned can be used. I can do it. Accordingly, the manufacturing temperature can be lowered, and for example, the transistor can be manufactured at room temperature. As a result, the transistor can be formed directly on a substrate having low heat resistance, such as a plastic substrate or a film substrate. These compound semiconductors or oxide semiconductors are
It can be used not only for the channel portion of the transistor but also for other purposes. For example, these compound semiconductors or oxide semiconductors can be used as resistance elements, pixel electrodes, and transparent electrodes. Further, they can be formed or formed at the same time as the transistor, so that cost can be reduced.

Alternatively, a transistor formed using an inkjet method or a printing method can be used. By these, manufacture at room temperature, manufacture at a low vacuum degree, or manufacture on a large substrate can be performed. Moreover, since it becomes possible to manufacture without using a mask (reticle),
The transistor layout can be easily changed. Furthermore, since it is not necessary to use a resist, the material cost is reduced and the number of processes can be reduced. Further, since a film is formed only on a necessary portion, the material is not wasted and cost can be reduced as compared with a manufacturing method in which etching is performed after film formation on the entire surface.

Alternatively, a transistor including an organic semiconductor or a carbon nanotube can be used. Thus, a transistor can be formed over a substrate that can be bent.
Therefore, it can be strong against impact.

In addition, various transistors can be used.

Various types of substrates can be used for forming the transistor, and the substrate is not limited to a specific type. As a substrate on which a transistor is formed, for example, a single crystal substrate, an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a paper substrate, a cellophane substrate,
Stone substrate, wood substrate, cloth substrate (including natural fiber (silk, cotton, hemp), synthetic fiber (nylon, polyurethane, polyester) or recycled fiber (acetate, cupra, rayon, recycled polyester)), leather substrate, rubber A substrate, a stainless steel / still substrate, a substrate having stainless steel / still / foil, or the like can be used. Or the skin of animals such as humans (
(Skin surface, dermis) or subcutaneous tissue may be used as the substrate. Alternatively, a transistor may be formed over a certain substrate, and then the transistor may be transferred to another substrate, and the transistor may be disposed over another substrate. As a substrate to which the transistor is transferred, a single crystal substrate, an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a paper substrate, a cellophane substrate, a stone substrate, a wood substrate,
Fabric substrate (natural fibers (silk, cotton, hemp), synthetic fibers (nylon, polyurethane, polyester)
Or recycled fibers (including acetate, cupra, rayon, recycled polyester)
Leather substrates, rubber substrates, stainless steel / still substrates, substrates having stainless steel / still foils, and the like can be used. Alternatively, the skin (skin surface, dermis) or subcutaneous tissue of an animal such as a human may be used as the substrate. By using these substrates, it is possible to form a transistor with good characteristics, a transistor with low power consumption, manufacture a device that is not easily broken, impart heat resistance, or reduce weight.

The structure of the transistor can take various forms. It is not limited to a specific configuration. For example, a multi-gate structure having two or more gate electrodes may be used. When the multi-gate structure is employed, the channel regions are connected in series, so that a plurality of transistors are connected in series. With the multi-gate structure, the off-state current can be reduced and the reliability can be improved by improving the withstand voltage of the transistor. Alternatively, when operating in the saturation region, even if the drain-source voltage changes, the current between the drain and source does not change so much, and the slope of the voltage / current characteristic can be made flat. By using a characteristic in which the slope of the voltage-current characteristic is flat, an ideal current source circuit and an active load having a very high resistance value can be realized. As a result, a differential circuit or a current mirror circuit with good characteristics can be realized.
Alternatively, a structure in which gate electrodes are arranged above and below the channel may be employed. By employing a structure in which gate electrodes are arranged above and below the channel, the channel region increases, so that the current value can be increased. Alternatively, a depletion layer can be easily formed and the S value can be reduced. When gate electrodes are provided above and below a channel, a structure in which a plurality of transistors are connected in parallel is obtained.

Alternatively, a structure in which a gate electrode is disposed over a channel region may be employed, or a structure in which a gate electrode is disposed under a channel region may be employed. Alternatively, a normal stagger structure or an inverted stagger structure may be used, the channel region may be divided into a plurality of regions, the channel regions may be connected in parallel, or the channel regions may be connected in series. Good. Also,
A source electrode or a drain electrode may overlap with the channel region (or a part thereof).
With the structure in which the source electrode or the drain electrode overlaps with the channel region (or part thereof), it is possible to prevent electric charges from being accumulated in part of the channel region and unstable operation. Further, an LDD region may be provided. By providing the LDD region, the off-state current can be reduced and the reliability can be improved by improving the withstand voltage of the transistor. Alternatively, when operating in the saturation region, even if the voltage between the drain and the source changes, the current between the drain and the source does not change so much, and the slope of the voltage-current characteristic can be made flat.

In this specification, one pixel represents the minimum unit of an image. Therefore, R (red) G
In the case of a full-color display device composed of (green) B (blue) color elements, one pixel is composed of R color element dots, G color element dots, and B color element dots. And Note that the color elements are not limited to three colors, and three or more colors may be used, or colors other than RGB may be used. For example, RGBW (W is white) may be added by adding white. Further, one or more colors such as yellow, cyan, magenta, emerald green, vermilion, and the like may be added to RGB. Alternatively, for example, a color similar to at least one of RGB may be added to RGB. For example, R, G, B1, and B2 may be used. B1 and B2 are both blue, but have slightly different frequencies. Similarly, R1, R2, G, and B may be used. By using such color elements, it is possible to perform display closer to the real thing or to reduce power consumption. A single pixel may have a plurality of dots of the same color element.
At that time, the plurality of color elements may have different sizes of regions contributing to display. Further, gradation may be expressed by controlling a plurality of dots of the same color element. This is called an area gradation method. Alternatively, the viewing angle may be widened by using a plurality of dots of the same color and using slightly different signals to be supplied to the dots. That is, a plurality of pixel electrodes having the same color element may have different potentials. As a result, the voltage applied to the liquid crystal molecules is different for each pixel electrode. Therefore, the viewing angle can be widened.

In this specification, one pixel represents one element whose brightness can be controlled. Therefore, as an example, one pixel represents one color element, and brightness is expressed by one color element. Therefore, at that time, in the case of a color display device composed of R (red), G (green), and B (blue) color elements, the minimum unit of an image is an R pixel, a G pixel, and a B pixel. It is assumed to be composed of three pixels. Note that the color elements are not limited to three colors, and three or more colors may be used, or colors other than RGB may be used. For example, RGBW (W is white) may be added by adding white. Further, one or more colors such as yellow, cyan, magenta, emerald green, vermilion, and the like may be added to RGB. Further, for example, a color similar to at least one of RGB may be added to RGB. For example, R, G, B1, and B2 may be used. B1 and B
Both are blue, but have slightly different frequencies. Similarly, R1, R2, G,
B may be used. By using such color elements, it is possible to perform display closer to the real thing or to reduce power consumption. As another example, when brightness is controlled using a plurality of areas for one color element, one area may be used as one pixel. Therefore, as an example, when area gradation is performed or when sub-pixels (sub-pixels) are provided, there are a plurality of brightness control areas for one color element, and the gradation is expressed as a whole. However, one pixel for controlling the brightness may be one pixel. Therefore, in that case, one color element is composed of a plurality of pixels. Alternatively, even if there are a plurality of areas for controlling the brightness in one color element, they may be combined into one pixel. Therefore, in that case, one color element is composed of one pixel. When brightness is controlled using a plurality of areas for one color element, the size of the area contributing to display may be different depending on the pixel. In addition, in a plurality of brightness control areas for one color element, a signal supplied to each may be slightly different to widen the viewing angle. That is, for one color element, the potentials of the pixel electrodes in each of a plurality of regions may be different from each other. As a result, the voltage applied to the liquid crystal molecules is different for each pixel electrode. Therefore, the viewing angle can be widened.

When it is explicitly described as one pixel (for three colors), it is assumed that three pixels of R, G, and B are considered as one pixel. When it is explicitly described as one pixel (for one color), it is assumed that when there are a plurality of areas for one color element, they are considered as one pixel.

In this specification, pixels may be arranged (arranged) in a matrix. Here, the pixel being arranged (arranged) in the matrix includes a case where the pixels are arranged in a straight line or a jagged line in the vertical direction or the horizontal direction. For example, when full color display is performed with three color elements (for example, RGB), the case where stripes are arranged and the case where dots of three color elements are arranged in a delta are included. further,
Including cases where Bayer is arranged. Note that the color elements are not limited to three colors, and may be more than that, for example, RGBW (W is white) or RGB in which one or more colors of yellow, cyan, magenta, etc. are added. Further, the size of the display area may be different for each dot of the color element. Thereby, power consumption can be reduced. Alternatively, the lifetime of the display element can be extended.

In this specification, an active matrix method in which an active element is included in a pixel or a passive matrix method in which an active element is not included in a pixel can be used.

In the active matrix system, not only transistors but also various active elements (active elements and nonlinear elements) can be used as active elements (active elements and nonlinear elements). For example, MIM (Metal Insulator Metal) or TFD (Th
inFilmDiode) or the like can also be used. These elements can be manufactured at low cost because they have few manufacturing processes. Alternatively, the yield can be increased. Furthermore, since the size of the element is small, the aperture ratio can be improved, and low power consumption and high luminance can be achieved.

Active elements (active elements, non-linear elements) other than active matrix systems
It is also possible to use a passive matrix type that does not use. Since no active element (active element or nonlinear element) is used, the number of manufacturing steps is small, and the manufacturing can be performed at low cost.
Alternatively, the yield can be increased. In addition, since an active element (an active element or a non-linear element) is not used, the aperture ratio can be improved, and low power consumption and high luminance can be achieved.

A transistor is an element having at least three terminals including a gate, a drain, and a source, has a channel region between the drain region and the source region, and includes the drain region, the channel region, and the source region. Current can be passed through. Here, since the source and the drain vary depending on the structure and operating conditions of the transistor, it is difficult to limit which is the source or the drain. Therefore, in this specification, a region functioning as a source and a drain may not be referred to as a source or a drain. In that case, as an example, there are cases where they are referred to as a first electrode and a second electrode, respectively.

The transistor may be an element having at least three terminals including a base, an emitter, and a collector. Similarly in this case, the emitter and the collector may be referred to as a first terminal and a second terminal.

A gate refers to the whole or part of a gate electrode and a gate wiring (also referred to as a gate line, a gate signal line, a scanning line, a scanning signal line, or the like). A gate electrode refers to a portion of a conductive film that overlaps with a semiconductor forming a channel region with a gate insulating film interposed therebetween. Note that a part of the gate electrode is an LDD (Lightly Doped Dr.
ain) region or a source region and a drain region may overlap with a gate insulating film. A gate wiring refers to a wiring for connecting a gate electrode of each transistor or a connection between the gate electrode and another wiring.

However, there are portions (regions, conductive films, wirings, etc.) that also function as gate electrodes and function as gate wirings. Such a portion (region, conductive film, wiring, or the like) may be called a gate electrode or a gate wiring. That is, there is a region where the gate electrode and the gate wiring cannot be clearly distinguished. For example, when a part of the gate wiring extended and the channel region overlaps, the portion (region, conductive film, wiring, etc.) functions as a gate wiring, but also as a gate electrode It is functioning. Therefore, such a portion (region, conductive film, wiring, or the like) may be called a gate electrode or a gate wiring.

A portion (region, conductive film, wiring, or the like) that is formed using the same material as the gate electrode and is connected by forming the same island as the gate electrode may also be referred to as a gate electrode. Similarly, a portion (a region, a conductive film, a wiring, or the like) formed using the same material as the gate wiring and connected by forming the same island (island) as the gate wiring may be referred to as a gate wiring. Such a part (
(Region, conductive film, wiring, etc.) do not overlap with the channel region in the strict sense,
In some cases, it does not have a function of connecting to another gate electrode. However, it is made of the same material as the gate electrode or gate wiring, and is the same island (island) as the gate electrode or gate wiring.
There are portions (regions, conductive films, wirings, etc.) that are connected by forming. Such a portion (region, conductive film, wiring, or the like) may also be called a gate electrode or a gate wiring.

For example, in a multi-gate transistor, one gate electrode and another gate electrode are often connected by a conductive film formed using the same material as the gate electrode. Such a portion (region, conductive film, wiring, or the like) is a portion (region, conductive film, wiring, or the like) for connecting the gate electrode to the gate electrode, and may be called a gate wiring. These transistors can be regarded as a single transistor, and may be referred to as a gate electrode.
That is, a portion (region, conductive film, wiring, or the like) that is formed using the same material as the gate electrode or gate wiring and is connected to form the same island (island) as the gate electrode or gate wiring is connected to the gate electrode or gate wiring. You can call it. Further, for example, a conductive film in a portion where the gate electrode and the gate wiring are connected and formed of a material different from the gate electrode or the gate wiring may be referred to as a gate electrode. You may call it.

The gate terminal refers to a part of a portion of the gate electrode (region, conductive film, wiring, or the like) or a portion electrically connected to the gate electrode (region, conductive film, wiring, or the like).

In the case of calling a gate wiring, a gate line, a gate signal line, a scanning line, a scanning signal line, or the like, the gate of the transistor may not be connected to the wiring. In this case, the gate wiring, the gate line, the gate signal line, the scanning line, and the scanning signal line are formed using the same layer as the gate of the transistor,
It may mean a wiring formed of the same material as the gate of the transistor or a wiring formed at the same time as the gate of the transistor. Examples include a storage capacitor wiring, a power supply line, a reference potential supply wiring, and the like.

A source refers to the whole or a part of a source region, a source electrode, and a source wiring (also referred to as a source line, a source signal line, a data line, a data signal line, or the like). The source region refers to a semiconductor region containing a large amount of P-type impurities (such as boron and gallium) and N-type impurities (such as phosphorus and arsenic). Therefore, a region containing a little P-type impurity or N-type impurity, that is, a so-called LDD (Lightly Doped Drain) region is not included in the source region. A source electrode refers to a portion of a conductive layer which is formed using a material different from that of a source region and is electrically connected to the source region. However, the source electrode
The source region may be referred to as a source electrode. The source wiring is a wiring for connecting between the source electrodes of each pixel or connecting the source electrode to another wiring.

However, there are portions (regions, conductive films, wirings, and the like) that also function as source electrodes and function as source wirings. Such a portion (region, conductive film, wiring, or the like) may be called a source electrode or a source wiring. That is, there is a region where the source electrode and the source wiring cannot be clearly distinguished. For example, in the case where a part of a source wiring that is extended and the source region overlap with each other, the portion (region, conductive film, wiring, etc.) functions as a source wiring, but as a source electrode Will also work. Thus, such a portion (region, conductive film, wiring, or the like) may be called a source electrode or a source wiring.

A portion (region, conductive film, wiring, etc.) that is formed of the same material as the source electrode and forms the same island (island) as the source electrode, or a portion that connects the source electrode and the source electrode (region, conductive) Films, wirings, etc.) may also be called source electrodes. Further, a portion overlapping with the source region may be called a source electrode. Similarly, a region formed of the same material as the source wiring and connected by forming the same island as the source wiring may be called a source wiring. Such a portion (region, conductive film, wiring, or the like) may not have a function of connecting to another source electrode in a strict sense. But,
There is a portion (a region, a conductive film, a wiring, or the like) formed of the same material as the source electrode or the source wiring and connected to the source electrode or the source wiring. Therefore, such a portion (region, conductive film, wiring, or the like) may also be referred to as a source electrode or a source wiring.

For example, a conductive film in a portion where the source electrode and the source wiring are connected and formed of a material different from that of the source electrode or the source wiring may be called a source electrode.
You may call it source wiring.

A source terminal refers to a part of a source region, a source electrode, or a portion (region, conductive film, wiring, or the like) electrically connected to the source electrode.

In the case of calling a source wiring, a source line, a source signal line, a data line, a data signal line, or the like, the source (drain) of the transistor may not be connected to the wiring. In this case, the source wiring, the source line, the source signal line, the data line, and the data signal line are a wiring formed of the same layer as the source (drain) of the transistor and a wiring formed of the same material as the source (drain) of the transistor. Alternatively, it may mean a wiring formed simultaneously with the source (drain) of the transistor. Examples include a storage capacitor wiring, a power supply line, a reference potential supply wiring, and the like.

The drain is the same as the source.

A semiconductor device refers to a device having a circuit including a semiconductor element (a transistor, a diode, a thyristor, or the like). Furthermore, a device that can function by utilizing semiconductor characteristics may be called a semiconductor device.

Display elements include optical modulation elements, liquid crystal elements, light emitting elements, EL elements (organic EL elements, inorganic EL elements)
Element or EL element including organic and inorganic substances), electron-emitting device, electrophoretic device, discharge device,
It refers to a light reflection element, a light diffraction element, a digital micromirror device (DMD), and the like. However, it is not limited to this.

A display device refers to a device having a display element. Note that the display device may be a display panel body in which a plurality of pixels including display elements or a peripheral drive circuit for driving the pixels is formed over the same substrate. Note that the display device includes a peripheral drive circuit arranged on the substrate by wire bonding or bumps, an IC chip connected by so-called chip on glass (COG), or an IC chip connected by TAB or the like. May be. Note that the display device may include a flexible wiring board (FPC) to which an IC chip, a resistor element, a capacitor element, an inductor, a transistor, and the like are attached. Note that the display device may include a printed wiring board (PWB) connected via a flexible wiring board (FPC) or the like, to which an IC chip, a resistance element, a capacitor element, an inductor, a transistor, or the like is attached. Note that the display device may include an optical sheet such as a polarizing plate or a retardation plate. Note that the display device may include a lighting device, a housing, a voice input / output device, an optical sensor, and the like. Here, the illumination device such as the backlight unit may include a light guide plate, a prism sheet, a diffusion sheet, a reflection sheet, a light source (LED, cold cathode tube, etc.), a cooling device (water cooling type, air cooling type) and the like. good.

The lighting device refers to a device having a backlight unit, a light guide plate, a prism sheet, a diffusion sheet, a reflection sheet, a light source (LED, cold cathode tube, hot cathode tube, etc.), a cooling device, and the like.

Note that a light-emitting device refers to a device having a light-emitting element or the like.

The reflection device refers to a device having a light reflection element, a light diffraction element, a light reflection electrode, and the like.

A liquid crystal display device refers to a display device having a liquid crystal element. The liquid crystal display device has a direct view type,
There are a projection type, a transmission type, a reflection type, and a semi-transmission type.

A driving device refers to a device having a semiconductor element, an electric circuit, and an electronic circuit. For example, a transistor that controls input of a signal from a source signal line into a pixel (sometimes referred to as a selection transistor or a switching transistor), a transistor that supplies voltage or current to a pixel electrode, or a voltage or current to a light-emitting element A transistor that supplies the voltage is an example of a driving device. Further, a circuit for supplying a signal to the gate signal line (sometimes referred to as a gate driver or a gate line driver circuit), a circuit for supplying a signal to the source signal line (source driver,
(Sometimes referred to as a source line driver circuit) is an example of a driver.

In some cases, a display device, a semiconductor device, a lighting device, a cooling device, a light-emitting device, a reflecting device, a driving device, and the like overlap each other. For example, the display device may include a semiconductor device and a light-emitting device, or the semiconductor device may include a display device and a driving device.

In this specification, when B is formed on A or B is formed explicitly on A, B is formed on A in direct contact. It is not limited to that. The case where it is not in direct contact, that is, the case where another object is interposed between A and B is also included. Here, A and B are objects (for example, devices, elements, circuits, wirings, electrodes, terminals,
A conductive film, a layer, and the like.

Therefore, for example, when it is explicitly described that the layer B is formed on the layer A (or on the layer A), the layer B is formed in direct contact with the layer A. And the case where another layer (for example, layer C or layer D) is formed in direct contact with the layer A, and the layer B is formed in direct contact therewith. Note that another layer (for example, the layer C or the layer D) may be a single layer or a multilayer.

Furthermore, the same applies to the case where B is explicitly described as being formed above A, and is not limited to the direct contact of B on A. This includes the case where another object is interposed in. Therefore, for example, when the layer B is formed above the layer A, the case where the layer B is formed in direct contact with the layer A and the case where another layer is formed in direct contact with the layer A. (For example, the layer C, the layer D, etc.) are formed, and the layer B is formed in direct contact therewith. Note that another layer (for example, the layer C or the layer D) may be a single layer or a multilayer.

When it is explicitly stated that B is formed on A directly in contact with B, it includes a case where B is formed on A directly in contact with another object between A and B. It shall not be included in the case of intervening.

The same applies to the case where B is below A or B is below A.

Degradation of characteristics of all transistors included in the shift register can be suppressed. Therefore, malfunction of a semiconductor device to which the shift register such as a liquid crystal display device is applied can be suppressed.

3A and 3B illustrate a structure of a flip-flop described in Embodiment 1. 2 is a timing chart illustrating the operation of the flip-flop illustrated in FIG. 1. 3A and 3B illustrate operation of the flip-flop illustrated in FIG. 1. 3A and 3B illustrate a structure of a flip-flop described in Embodiment 1. 3A and 3B illustrate a structure of a flip-flop described in Embodiment 1. 3 is a timing chart illustrating operation of the flip-flop described in Embodiment 1; 3A and 3B illustrate a structure of a flip-flop described in Embodiment 1. 3A and 3B each illustrate a structure of a display device shown in Embodiment 1; 9 is a timing chart illustrating a writing operation of the display device illustrated in FIG. FIG. 5 illustrates a structure of a shift register shown in Embodiment 1; 11 is a timing chart illustrating operation of the shift register illustrated in FIG. 11 is a timing chart illustrating operation of the shift register illustrated in FIG. FIG. 5 illustrates a structure of a shift register shown in Embodiment 1; FIG. 5 illustrates a structure of a shift register shown in Embodiment 1; FIG. 5 illustrates a structure of a shift register shown in Embodiment 1; FIG. 6 illustrates a structure of a display device described in Embodiment 2; FIG. 5 illustrates a structure of a shift register shown in Embodiment 1; 3A and 3B each illustrate a structure of a display device shown in Embodiment 1; FIG. 19 is a timing chart illustrating a writing operation of the display device illustrated in FIG. 18. 3A and 3B each illustrate a structure of a display device shown in Embodiment 1; 3A and 3B illustrate a structure of a flip-flop described in Embodiment 1. FIG. 5 illustrates a structure of a flip-flop shown in Embodiment 2; FIG. 5 illustrates a structure of a flip-flop shown in Embodiment 4; 24 is a timing chart illustrating operation of the flip-flop illustrated in FIG. FIG. 2 is a top view of the flip-flop shown in FIG. 1. FIG. 14 is a diagram illustrating a configuration of a buffer illustrated in FIG. 13. 4A and 4B illustrate a structure of a flip-flop shown in Embodiment 3. 28 is a timing chart illustrating the operation of the flip-flop illustrated in FIG. FIG. 5 illustrates a structure of a shift register shown in Embodiment 3; 30 is a timing chart illustrating operation of the shift register illustrated in FIG. 6 is a timing chart illustrating operation of the flip-flop described in Embodiment 2. 6 is a timing chart illustrating operation of the flip-flop described in Embodiment 2. FIG. 5 illustrates a structure of a shift register described in Embodiment 2; FIG. 5 illustrates a structure of a shift register described in Embodiment 2; 34 is a timing chart illustrating operation of the shift register illustrated in FIG. 34 is a timing chart illustrating operation of the shift register illustrated in FIG. 7A and 7B illustrate a structure of a signal line driver circuit described in Embodiment 5. 38 is a timing chart illustrating operation of the signal line driver circuit illustrated in FIG. 7A and 7B illustrate a structure of a signal line driver circuit described in Embodiment 5. 40 is a timing chart illustrating operation of the signal line driver circuit illustrated in FIG. 7A and 7B illustrate a structure of a signal line driver circuit described in Embodiment 5. 7A and 7B illustrate a structure of a protection diode described in Embodiment 6. 7A and 7B illustrate a structure of a protection diode described in Embodiment 6. 7A and 7B illustrate a structure of a protection diode described in Embodiment 6. 8A and 8B illustrate a structure of a display device described in Embodiment 7. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. Sectional drawing of the display element of a semiconductor device. Sectional drawing of the display element of a semiconductor device. Sectional drawing of the display element of a semiconductor device. FIG. 6 is a top view of a display element of a semiconductor device. FIG. 6 is a top view of a display element of a semiconductor device. FIG. 6 is a top view of a display element of a semiconductor device. FIG. 6 illustrates a peripheral circuit configuration of a semiconductor device. FIG. 6 illustrates a peripheral circuit configuration of a semiconductor device. 3A and 3B illustrate a panel circuit configuration of a semiconductor device. 3A and 3B illustrate a panel circuit configuration of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 6 illustrates a peripheral circuit configuration of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. FIG. 14 is a cross-sectional view of a semiconductor device. 10A and 10B illustrate a peripheral component member of a semiconductor device. FIG. 6 illustrates a peripheral circuit configuration of a semiconductor device. 10A and 10B illustrate a peripheral component member of a semiconductor device. 10A and 10B illustrate a peripheral component member of a semiconductor device. 10A and 10B illustrate a peripheral component member of a semiconductor device. 6A and 6B illustrate a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. 2A and 2B are a pixel layout example and a cross-sectional view of a semiconductor device. Sectional drawing of the display element of a semiconductor device. 4A and 4B illustrate a device for forming a display element of a semiconductor device. 4A and 4B illustrate a device for forming a display element of a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device. 8A and 8B illustrate one method for driving a semiconductor device.