JP6205014B2 - Display device - Google Patents

Description

The present invention relates to a driving circuit for a display device. Furthermore, the present invention includes an electronic device manufactured using the driving circuit of the display device. Note that in this specification, a display device includes a liquid crystal display device using a liquid crystal element for a pixel and a light-emitting display device using a self-light-emitting element such as an organic electroluminescence (EL) element. A driving circuit refers to a circuit that inputs a video signal to a pixel arranged in a display device and performs processing for displaying a video, and includes a pulse circuit including a shift register and an amplifier. An amplifier circuit is included.

In recent years, a display device in which a semiconductor thin film is formed over an insulator, particularly a glass substrate, in particular, an active matrix display device using a thin film transistor (hereinafter referred to as TFT) has become widespread. An active matrix display device using TFTs has hundreds of thousands to millions of pixels arranged in a matrix, and displays the image by controlling the charge of each pixel by the TFT arranged in each pixel. It is carried out.

Furthermore, as a recent technology, in addition to the pixel TFT constituting the pixel, TF is provided in the peripheral region of the pixel portion.
A technology related to polysilicon TFTs that simultaneously form a drive circuit using T has been developed, greatly contributing to downsizing and low power consumption of the device. The display device has become an indispensable device for the display unit and the like.

As a drive circuit for a display device, a CMOS circuit in which an N-type TFT and a P-type TFT are combined is generally used. As a feature of CMOS circuits, logic changes (from Hi potential to Lo
The current flows only at the moment (from the potential or from the Lo potential to the Hi potential), and does not flow while holding a certain logic (actually there is a small leakage current), so the current consumption in the entire circuit Can be kept low, and it is advantageous for high-speed driving.

Demand for display devices using liquid crystals and self-luminous elements has been increasing rapidly as mobile electronic devices have become smaller and lighter, but their production costs have been reduced sufficiently in terms of yield and other factors. It is difficult to suppress. It is easily predicted that future demand will increase more rapidly, and it is therefore desirable to be able to supply display devices at a lower cost.

As a method for manufacturing a driver circuit over an insulator, an active layer, a plurality of photomasks,
It is common to create patterns by exposing and etching patterns such as wiring, but since the large number of processes at this time directly affects the manufacturing cost, it is possible to manufacture with as few processes as possible. Ideal to do. Therefore, a driving circuit that has been configured by a conventional CMOS circuit is configured by using only N-type or P-type TFTs. By this method, part of the ion doping process can be omitted, and the number of photomasks can be reduced.

(Problems of the technology prior to the present invention)
FIG. 9A shows an example of a CMOS inverter (I) that is generally used conventionally and inverters (II) and (III) that are configured using TFTs having only one polarity. (II) is TFT
A load type inverter (III) is a resistance load type inverter. Each operation will be described below.

FIG. 9B shows the waveform of a signal input to the inverter. Here, the input signal amplitude is between VDD and GND (GND <VDD). Specifically, it is considered that GND = 0 [V].

The circuit operation will be described. For clarity and simplicity of explanation, N constituting the circuit
The threshold voltage of the type TFT is uniform (VthN) assuming that there is no variation. Similarly, the P-type TFT is set to be uniform (VthP).

When a signal as shown in FIG. 9B is input to the CMOS inverter, the potential of the input signal becomes Hi.
At (VDD), the P-type TFT 901 is turned off and the N-type TFT 902 is turned on, so that the potential of the output node becomes Lo (GND). Conversely, when the potential of the input signal is Lo, P
When the type TFT 901 is turned on and the N type TFT 902 is turned off, the potential of the output node becomes Hi (FIG. 9C).

Next, the operation of the TFT load type inverter (II) will be described. Consider the case where a signal as shown in FIG. First, when the input signal is Lo, the N-type TFT 9
04 turns off. On the other hand, since the load TFT 903 always operates in saturation, the potential of the output node is raised in the Hi direction. On the other hand, when the input signal is Hi, the N-type TFT 904
Turns on. Here, by making the current capability of the N-type TFT 904 sufficiently higher than the current capability of the load TFT 903, the potential of the output node is lowered in the Lo direction.

Similarly, for the resistance load type inverter (III), the ON resistance value of the N type TFT 906 is
By making it sufficiently lower than the resistance value of the load resistor 905, when the input signal is Hi, the N-type TFT 906 is turned ON, and the output node is pulled down in the Lo direction. When the input signal is Lo, the N-type TFT 906 is turned off and the output node is pulled up in the Hi direction.

However, when using a TFT load type inverter or a resistance load type inverter, there are the following problems. FIG. 9D shows the output waveform of the TFT load type inverter.
When the output is Hi, the potential is lower than VDD by the amount indicated by 907. Load TFT90
3, if the terminal on the output node side is the source and the terminal on the power supply VDD side is the drain, the gate electrode and the drain region are connected, so the potential of the gate electrode at this time is VDD. Further, since the condition for turning on the load TFT is (the gate-source voltage of the TFT 903> VthN), the potential of the output node is (VDD−VthN) at the maximum.
) Only rises. That is, 907 is equal to VthN. Furthermore, the load TFT 903
Depending on the ratio of the current capability of the N-type TFT 904, when the output potential is Lo, the potential becomes higher than GND by the amount indicated by 908. In order to make this sufficiently close to GND, the load T
It is necessary to sufficiently increase the current capability of the N-type TFT 904 with respect to the FT 903. Similarly, FIG. 9E shows an output waveform of a resistance load type inverter.
Depending on the ratio between the resistance value of N-type TFT 906 and the ON resistance of the N-type TFT 906, the potential increases by the amount indicated by 909. In other words, when an inverter configured using only one polarity TFT shown here is used, the amplitude of the output signal is attenuated with respect to the amplitude of the input signal. In order to configure the drive circuit, an output must be obtained without the amplitude being attenuated.

The present invention has been made in view of the above problems, and can be manufactured at a low cost by reducing the manufacturing process by using a TFT having only one polarity, and can provide an output without amplitude attenuation. It is an object to provide a driver circuit for a display device that can be obtained.

In the TFT load type inverter shown in (II) of FIG. 9A, the conditions for the output signal amplitude to normally take VDD-GND are considered. First, in the circuit as shown in FIG. 1A, when the potential of the output signal becomes Lo, in order to bring the potential sufficiently close to GND, the resistance value between the power supply VDD and the output node is It is sufficient that the resistance value between the GND and the output node is sufficiently low. That is, during the period when the N-type TFT 102 is ON, the N-type TFT
101 should just be OFF. Second, when the potential of the output signal becomes Hi, in order for the potential to be equal to VDD, the absolute value of the gate-source voltage of the N-type TFT 101 is Vth.
It is only necessary to always exceed N. That is, in order to satisfy the condition that the Hi potential of the output node becomes VDD, the potential of the gate electrode of the N-type TFT 101 needs to be higher than (VDD + VthN). Since there are only two types of power supply to the circuit, VDD and GND, the condition cannot be satisfied unless there is a third power supply having a higher potential than VDD.

Therefore, the following measures are taken in the present invention. As shown in FIG. 1B, an N-type TFT
A capacitor 103 is provided between the gate and the source 101. When the potential of the output node is raised when the gate electrode of the N-type TFT 101 enters a floating state with a certain potential, the capacitance 103
Due to the capacitive coupling, the potential of the gate electrode of the N-type TFT 101 is raised with the increase in potential of the output node. If this effect is utilized, the potential of the gate electrode of the N-type TFT 101 can be made higher than VDD (more precisely, higher than VDD + VthN). Therefore, the potential of the output node can be sufficiently raised to VDD.

Note that the capacitor 103 illustrated in FIG. 1B may actually be formed as a capacitor portion.
A parasitic capacitance between the gate and source of the TFT 101 may be used.

  The configuration of the present invention will be described below.

According to the first aspect of the present invention, the driver circuit for the display device according to the present invention includes a first transistor in which the first impurity region is electrically connected to the first power source, and the first impurity region is in the second state. A second transistor electrically connected to the first power source, a third transistor whose first impurity region is electrically connected to the first power source, and a first impurity region serving as the second power source. A display device drive circuit having a fourth transistor and a capacitor electrically connected to the first transistor, wherein
The fourth to fourth transistors all have the same conductivity type, and the second transistor of the first transistor
And the second impurity region of the second transistor are electrically connected to one terminal of the capacitor, the second impurity region of the third transistor, and the fourth impurity region of the second transistor, The second impurity region of the transistor and the gate electrode of the first transistor are both electrically connected to the other terminal of the capacitor, the gate electrode of the second transistor, and the fourth electrode The gate electrode of the transistor is electrically connected to the input signal line,
The gate electrode of the third transistor is electrically connected to the first power source.

According to a second aspect of the present invention, the driver circuit for the display device according to the present invention includes a first transistor in which the first impurity region is electrically connected to the first power source, and the first impurity region is in the second state. A second transistor electrically connected to the first power source, a third transistor whose first impurity region is electrically connected to the first power source, and a first impurity region serving as the second power source. And a fourth transistor electrically connected to the display device, and a capacitor, wherein the first to fourth transistors are all of the same conductivity type. The second impurity region and the second impurity region of the second transistor are both electrically connected to one terminal of the capacitor, the second impurity region of the third transistor, Second impurity region of transistor 4 A gate electrode of the first transistor,
Both are electrically connected to the other terminal of the capacitor, and the gate electrode of the second transistor and the gate electrode of the fourth transistor are electrically connected to the first input signal line, The gate electrode of the third transistor is electrically connected to the second input signal line.

According to a third aspect of the present invention, in the display device driving circuit according to the second aspect of the present invention, in the second aspect, the second input signal line receives an inverted signal of a signal input to the first input signal line. It is characterized by being a signal line.

According to a fourth aspect of the present invention, in the display device driving circuit according to the first or second aspect of the present invention, in the first or second aspect, the capacitor includes a gate electrode of the first transistor and one of the impurity regions. It is characterized by using a capacity between.

According to a fifth aspect of the present invention, in the display device drive circuit according to the first or second aspect of the present invention, the capacitor is any one of an active layer material, a material constituting a gate electrode, or a wiring material. It is characterized by a capacity constituted by using two materials.

According to a sixth aspect of the present invention, in the display device driving circuit according to the present invention, the one conductivity type is an N-channel type in any one of the first to fifth aspects.

According to a seventh aspect of the present invention, in the display device drive circuit according to the present invention, the one conductivity type is a P-channel type in any one of the first to fifth aspects.

According to an eighth aspect of the present invention, in the display device driving circuit according to the sixth aspect, the potential when the input signal is the Hi potential is equal to the third power supply potential, and the potential when the input signal is the Lo potential is the first potential. When the power source potential is equal to 4, the second power source potential ≦ the fourth power source potential <the third power source potential ≦ the first power source potential
The power supply potential is satisfied.

According to a ninth aspect of the present invention, in the display device driving circuit according to the seventh aspect, the potential when the input signal is the Hi potential is equal to the third power supply potential, and the potential when the input signal is the Lo potential is the first potential. When the power supply potential is equal to 4, the first power supply potential ≦ the fourth power supply potential <the third power supply potential ≦ the second power supply potential
The power supply potential is satisfied.

According to a tenth aspect of the present invention, the drive circuit for the display device according to the present invention includes the first to ninth aspects.
In any one of the above, the driving circuit of the display device is an inverter, a buffer, or a level shifter, or is a constituent requirement of the inverter, buffer, or level shifter.

With the display device driver circuit of the present invention, the display device driver circuit and the pixel portion can be formed using only one-conductivity type TFT, and the manufacturing cost of the display device can be reduced, thereby reducing costs and yield. The display device can be supplied at a lower cost.

4A and 4B illustrate an operation principle of a driver circuit of a display device of the present invention. The figure which shows the waveform of the inverter which is a fundamental form of the drive circuit of the display apparatus of this invention, and its input-output signal. The figure which shows the example of a connection in the case of using the inverter which is one fundamental form of the drive circuit of the display apparatus of this invention connected in multiple stages. The figure which shows the waveform of the level shifter shown as an Example of the drive circuit of the display apparatus of this invention, and its input-output signal. An explanatory view about operation of a level shifter, and a figure showing an example of composition of a level shifter. The figure which shows the structural example of the 2-input type level shifter in the case of having an inversion signal. 1 is a schematic view of a display device manufactured by applying the present invention. FIG. 14 illustrates an example of application of a driver circuit of a display device of the present invention to an electronic device. The figure which shows the structure of a conventional CMOS inverter and a load type inverter, and the waveform of each input-output signal. The figure explaining the input signal and circuit operation | movement in a 4 TFT type inverter and a 3 TFT type inverter.

FIG. 2A illustrates one mode of a driver circuit of a display device of the present invention, which is a circuit that functions as an inverter. A portion formed by the N-type TFTs 201 to 204 and the capacitor 205 and surrounded by a dotted frame 206 corresponds to the circuit shown in FIG. A portion surrounded by a dotted frame 210 constitutes an output amplitude compensation circuit. The output amplitude compensation circuit 210 is intended to create a floating state in the gate electrode of the N-type TFT 203, and as long as it has the same function, FIG.
It is not limited to the configuration.

In the circuit of FIG. 2A, an input signal is input to the gate electrodes of the N-type TFT 202 and the N-type TFT 204. The N-type TFT 201 functions as a load, and the N-type TFTs 201 and 20
2 is input to the gate electrode of the N-type TFT 203 (the node in FIG. 2A is set to α).

The operation details of the circuit will be described step by step. The power supply potential is VDD and GND,
The amplitude of the input signal is also VDD (Hi) -GND (Lo). First, the potential of the input signal is Hi
At this time, the N-type TFTs 202 and 204 are turned on. Here, the N-type TFT 201 is saturated because the gate electrode and the drain region are connected. However, by making the current capability of the N-type TFT 202 sufficiently higher than the current capability of the N-type TFT 201, the node α Is pulled down to the GND side. As a result, the N-type TFT 203 is turned OFF, and the Lo potential is output to the output node.

Subsequently, when the potential of the input signal is Lo, the N-type TFTs 202 and 204 are turned off. As a result, the potential of the node α is raised to the VDD side, and the potential is (VDD−VthN).
When it becomes, it becomes a floating state once. On the other hand, when the potential of the node α starts to rise, the N-type TFT 203 is eventually turned on, and the potential of the output node is raised to the VDD side. When the node α is in a floating state, the potential of the output node continues to rise, so that the N-type TFT 20
As a result of the presence of the gate-source capacitance 205, the potential of the node α in the floating state also increases as the potential of the output node increases. As a result, the potential of the node α becomes (VDD + Vth
N) can be a higher potential. Therefore, the Hi potential is output to the output node,
The potential at this time is equal to VDD.

By the operation as described above, the amplitude of the output signal can be obtained without attenuation with respect to the amplitude of the input signal. A method of raising the potential by using capacitive coupling between two points in this way is called a bootstrap method. 2B shows the waveform of the input signal of the circuit shown in FIG. 2A, and FIG. 2C shows the waveform of the potential at the node α. (D) shows the waveform of the output signal. In FIG. 2C, the potential indicated by 208 is V more than VDD.
The potential is lowered by thN, and the potential of the node α is raised by the amount indicated by 207 by the bootstrap. As a result, as shown in FIG. 2D, when the output node is at the Hi potential, the potential rises to VDD, and an output signal having an amplitude between VDD and GND can be obtained.

By the way, in the drive circuit of the display device of the present invention, the operation is based on the amplitude compensation of the output signal by the bootstrap method. At that time, the gate electrode of the TFT using the capacitive coupling is in a floating state. Is the premise. FIG. 10 shows a configuration example of a circuit using the bootstrap method. FIG. 10A shows a basic configuration of a driver circuit of the display device of the present invention, but the node α is in a floating state. Therefore, the potential of the node α is raised using the gate-source capacitance 1005 of the TFT 1003, thereby compensating the amplitude of the output signal. FIG. 10B shows a circuit including three TFTs. Similarly, since the node β is in a floating state, the node 100 is used by utilizing the gate-source capacitance 1009 of the TFT 1007. The potential of β is raised, thereby compensating for the amplitude of the output signal.

Next, the amplitude of the input signal and the power supply potential will be considered. The power supply potential on the high potential side is now VDD
The power supply potential on the low potential side is GND, the amplitude of the input signal (in) is VDD-GND, and inb is an inverted signal of the input signal. Here, the amplitude of in and inb is VDD3
Consider the state of the nodes α and β when −GND (where GND <VthN <VDD3 <VDD−VthN). In FIG. 10A, when inb is Hi, N
The gate electrode potential of the type TFT 1001 is VDD3. Since VthN <VDD3,
The N-type TFT 1001 is turned on, the potential of the node α is raised to the VDD side, and the potential is (
When it becomes VDD3-VthN), it enters a floating state. That is, the Hi potential of inb is V
If it exceeds thN, the node α can surely be in a floating state, and an operation of raising the gate electrode potential of the N-type TFT 1003 by bootstrap becomes possible. on the other hand,
In FIG. 10B, since the gate electrode potential of the N-type TFT 1006 is always VDD, when inb is Hi, the potential of the node β is raised to VDD3. However, now VD
Since D3 <VDD−VthN, the N-type TFT 1006 is always on regardless of the potential of the input signal. Therefore, the node β is not in a floating state. Therefore, the potential of the node β cannot be raised by bootstrap. That is, FIG. 10 (B)
In the case of the circuit shown in FIG. 2, in order for the node β to be in a floating state, there is a minimum condition that at least the Hi potential is (VDD−VthN) or more when the Lo potential of inb is GND. And it is disadvantageous when considering the characteristics variation of TFT.

Thus, under certain conditions when the amplitude of the input signal is smaller than the power supply voltage,
In the configuration as shown in FIG. 10B, there is a possibility that the floating state cannot be given to the node β. On the other hand, in the configuration shown in FIG. There is merit that can be made in the state.

  Examples of the present invention will be described below.

FIG. 3A illustrates a circuit in which a plurality of inverters which are one form of the driver circuit of the display device of the present invention are connected. Such a circuit is often used as a buffer in a driver circuit or the like of a display device. Here, when the circuit as shown in FIG. 3A is used, the following disadvantages can be mentioned.

In FIG. 3A, when the input signal is Hi, the N-type TFT 302 is turned on.
Here, the N-type TFT 301 functions as a load in which the gate and the drain are short-circuited,
Since saturation operation is always performed, VDD-GND is turned on when the N-type TFT 302 is turned ON.
A through current flows between them. The same applies to the TFTs 303, 304 and 305, 306 at each stage, and the current consumption increases.

As an example for avoiding such a problem, there is a method using a two-input type inverter as shown in FIG. In the case of such a circuit, the TFT arranged between VDD and GND has an exclusive operation since the polarity of the input signal is always reversed, and therefore, a through current does not flow.

However, in the case of using the circuit of FIG. 3B, it is necessary to prepare an inverted and non-inverted two-phase signal as an input signal.

Therefore, as a combination of both, as shown in FIG. 3C, the first input uses the one-input inverter of the present invention and the second and subsequent stages use the two-input inverter. As for the input of the second stage, it is only necessary to input the output signal of the previous stage to one side and the input signal of the previous stage to the other side. As a result, it can be used as a buffer that is of a single input type and has a minimum through current.

The driver circuit of the display device of the present invention can easily function as a level shifter by applying a potential different from the amplitude potential of the input signal as a power supply potential supplied to the circuit. An example is shown below.

First, three potentials of GND, VDD1, and VDD2 are considered as power supply potentials, and the magnitude relationship of each is GND <VDD1 <VDD2. At this time, a case where a signal having an amplitude between GND and VDD1 is input and converted into an amplitude between GND and VDD2 is taken out as an example.

An example is shown in FIG. The configuration of the circuit may be the same as that of the embodiment and Example 1.
The amplitude of the input signal is between GND and VDD1, and the potential of the power source connected to one end of the impurity region of the N-type TFTs 401 and 403 is VDD2.

The operation of the circuit will be described. The waveform of the input signal is shown in FIG. GND-VDD1
A signal having an amplitude in between is input to the gate electrodes of the N-type TFTs 402 and 404. When the input signal is at the Hi potential, the N-type TFTs 402 and 404 are turned on, the potential at the node α is pulled down to the GND side, and the N-type TFT 403 is turned off. Therefore, the potential at the output node becomes the Lo potential.

When the input signal is at the Lo potential, the N-type TFTs 402 and 404 are turned off, and the potential at the node α is raised to the VDD2 side. Therefore, the N-type TFT 403 is turned on and the potential of the output node rises. On the other hand, the potential at the node α is (VDD2-N type TFT).
When the absolute value of the threshold voltage (403) is reached, the floating state is entered. Thereafter, as the potential of the output node rises, the potential of the node α is further raised by the capacitive coupling 405 existing between the gate and the source of the N-type TFT 403, and takes a potential higher than VDD2 (FIG. 4C).
). Therefore, the potential of the output node becomes the Hi potential, and a signal having an amplitude between GND and VDD2 is output (solid line in FIG. 4D).

The reason why the circuit shown in this embodiment can be easily handled as a level shifter is that the gate electrodes of the TFTs 401 and 403 connected to the high potential side power supply (VDD2) do not have a low voltage amplitude signal input. It is done. In the two-input circuit shown in FIG. 5A, even if a signal having a low voltage amplitude is input to the TFT 501 connected to the high potential side power supply (VDD2), the node β
Can only rise to near VDD1. Accordingly, the TFT 503 cannot be sufficiently turned on, and the gate electrode potential of the TFT 503 cannot be raised by using capacitive coupling, so that normal operation cannot be expected.

Therefore, when the load applied immediately after the level shifter shown in this embodiment is large and a configuration of a buffer or the like is required, two stages of one-input type circuits are used as shown in FIG. All subsequent input signal amplitudes must be high voltage amplitudes. In FIG. 5B, a TFT to which a signal having a low voltage amplitude is input is limited to a portion surrounded by a dotted frame 506, and two stages of one-input type circuits are stacked to form a third stage. Since the two inputs (inputs to the gate electrodes of the TFTs 507 and 508) are both high voltage amplitude signals, they can operate normally.

Further, in the case where the signal to be subjected to amplitude conversion has an inverted signal, the output signal of each other may be used as the inverted input of the next stage. An example is shown in FIG. Input signals are in and inb, which are input to the gate electrodes of the TFTs 602 and 614, respectively.
The output of the first stage 650 of the level shifter is input to the TFTs 606 and 617 of the second stage.
Are input to the second-stage TFTs 605 and 618. Since the input signal to the second stage is a signal having a high voltage amplitude, it will function normally as a buffer thereafter, and output signals Out and outb are obtained from the final stage.

In this embodiment, an example in which a display device is manufactured using the display device driving circuit of the present invention will be described.

FIG. 7 is a schematic diagram of the display device. A source signal line driver circuit 701, a gate signal line driver circuit 702, and a pixel portion 703 are formed over the substrate 700 by integral formation. In the pixel portion, a portion surrounded by a dotted frame 710 is one pixel. In the example of the figure, a pixel of a liquid crystal display device is shown, and a charge applied to one electrode of a liquid crystal element is controlled by one TFT (hereinafter referred to as a pixel TFT). A signal input to the source signal line driver circuit 701 and the gate signal line driver circuit 702 is a flexible print circuit (FPC).
) 704 is supplied from the outside via 704.

The display device shown in this embodiment is configured using the drive circuit of the display device of the present invention, so that the drive circuit constituting the entire display device including the pixel portion has the same polarity as the pixel TFT. This TFT is manufactured using only the TFT (for example, N-type TFT). Thereby, it is possible to omit the ion doping step of imparting P-type to the semiconductor layer, which can contribute to reduction of manufacturing cost, improvement of yield, and the like.

Although the polarity of the TFT constituting the display device of this embodiment is N-type, it is of course possible to configure the driving circuit and the pixel TFT using only the P-type TFT according to the present invention. In this case, it is noted that the ion doping step to be omitted is a step of imparting N-type to the semiconductor layer. The present invention can be applied not only to a liquid crystal display device but also to any device that is manufactured by integrally forming a drive circuit on an insulator.

The driver circuit for the display device of the present invention can be applied to manufacture of a display device used in various electronic devices. Examples of such electronic devices include portable information terminals (electronic notebooks, mobile computers, mobile phones, etc.), video cameras, digital cameras, personal computers, televisions, mobile phones, and the like. An example of them is shown in FIG.

FIG. 8A illustrates a liquid crystal display (LCD), which includes a housing 3001, a support base 3002, a display portion 3003, and the like. A driver circuit of the display device of the present invention includes a display portion 3003.
It can be applied to the production of

FIG. 8B illustrates a video camera, which includes a main body 3011, a display portion 3012, and an audio input portion 301.
3, an operation switch 3014, a battery 3015, an image receiving unit 3016, and the like. The driver circuit of the display device of the present invention can be applied to manufacturing the display portion 3012.

FIG. 8C illustrates a laptop personal computer, which includes a main body 3021 and a housing 3022.
, A display unit 3023, a keyboard 3024, and the like. The driver circuit of the display device of the present invention can be applied to manufacturing the display portion 3023.

FIG. 8D illustrates a portable information terminal, which includes a main body 3031, a stylus 3032, and a display portion 303.
3, an operation button 3034, an external interface 3035, and the like. The driver circuit of the display device of the present invention can be applied to manufacturing the display portion 3033.

FIG. 8E illustrates a sound reproducing device, specifically an in-vehicle audio device.
, A display unit 3042, operation switches 3043 and 3044, and the like. The driver circuit of the display device of the present invention can be applied to manufacturing the display portion 3042. In this embodiment, the in-vehicle audio device is taken as an example, but it may be used for a portable or home audio device.

FIG. 8F illustrates a digital camera, which includes a main body 3051, a display portion (A) 3052, and an eyepiece portion 3.
053, an operation switch 3054, a display portion (B) 3055, a battery 3056, and the like. The display device drive circuit of the present invention includes a display portion (A).
The present invention can be applied to manufacture of 3052 and the display portion (B) 3055.

FIG. 8G illustrates a mobile phone, which includes a main body 3061, an audio output unit 3062, and an audio input unit 306.
3, a display unit 3064, an operation switch 3065, an antenna 3066, and the like. The driver circuit for the display device of the present invention can be applied to manufacture of the display portion 3064.

It should be noted that the examples shown in this embodiment are just examples, and the present invention is not limited to these applications.

Claims (2)

A pixel and a driving circuit;
The drive circuit includes first to eighth transistors,
The first to eighth transistors have the same conductivity type,
A gate of the second transistor is electrically connected to the first wiring;
The first wiring has a function of supplying a first signal;
A gate of the second transistor is electrically connected to a gate of the fourth transistor;
A gate of the second transistor is electrically connected to a gate of the fifth transistor;
A gate of the sixth transistor is electrically connected to a gate of the eighth transistor;
One of a source and a drain of the first transistor is electrically connected to a gate of the first transistor;
The other of the source and the drain of the first transistor is electrically connected to the gate of the third transistor;
The first transistor has a function of controlling supply of a potential for turning on the third transistor to the gate of the third transistor;
The second transistor has a function of controlling supply of a potential for turning off the third transistor to the gate of the third transistor;
The third transistor has a function of controlling supply of a potential for turning on the sixth transistor to the gate of the sixth transistor;
The fourth transistor has a function of controlling supply of a potential for turning off the sixth transistor to the gate of the sixth transistor;
The fifth transistor has a function of controlling supply of a potential for turning on the seventh transistor to a gate of the seventh transistor;
The sixth transistor has a function of controlling supply of a potential for turning off the seventh transistor to the gate of the seventh transistor;
The seventh transistor has a function of controlling supply of a first potential to one of a source and a drain of the eighth transistor;
The eighth transistor has a function of controlling supply of a second potential to one of a source and a drain of the seventh transistor;
The display device, wherein a potential corresponding to an output signal from one of a source and a drain of the seventh transistor is input to the pixel. A pixel and a driving circuit;
The drive circuit includes first to eighth transistors,
The pixel includes a ninth transistor;
The conductivity types of the first to ninth transistors are the same,
A gate of the second transistor is electrically connected to the first wiring;
The first wiring has a function of supplying a first signal;
A gate of the second transistor is electrically connected to a gate of the fourth transistor;
A gate of the second transistor is electrically connected to a gate of the fifth transistor;
A gate of the sixth transistor is electrically connected to a gate of the eighth transistor;
One of a source and a drain of the first transistor is electrically connected to a gate of the first transistor;
The other of the source and the drain of the first transistor is electrically connected to the gate of the third transistor;
The first transistor has a function of controlling supply of a potential for turning on the third transistor to the gate of the third transistor;
The second transistor has a function of controlling supply of a potential for turning off the third transistor to the gate of the third transistor;
The third transistor has a function of controlling supply of a potential for turning on the sixth transistor to the gate of the sixth transistor;
The fourth transistor has a function of controlling supply of a potential for turning off the sixth transistor to the gate of the sixth transistor;
The fifth transistor has a function of controlling supply of a potential for turning on the seventh transistor to a gate of the seventh transistor;
The sixth transistor has a function of controlling supply of a potential for turning off the seventh transistor to the gate of the seventh transistor;
The seventh transistor has a function of controlling supply of a first potential to one of a source and a drain of the eighth transistor;
The eighth transistor has a function of controlling supply of a second potential to one of a source and a drain of the seventh transistor;
A display device, wherein a potential corresponding to an output signal from one of a source and a drain of the seventh transistor is input to a gate of the ninth transistor.

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