JP2003223138A - Light emitting device and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device having pixels that have a constitution in which variation in the threshold values of TFTs is corrected by eliminating the adverse effect caused by the deviation in capacitive values. <P>SOLUTION: A voltage which is equal to a threshold value of a TFT 110 is held in a capacitive means 111. When video signals are received from a source signal line, the voltage held in the means are added to the signals and applied to a gate electrode of the TFT 110. Even though the threshold value is varied for every pixel, adverse effect caused by the variation in the threshold value is eliminated because the means 111 holds a respective threshold value for every pixel. The preservation of the threshold value is only conducted by the means 111 and adverse effect of the variation in the capacitive values does not occur when the video signals are written because the voltage between both electrodes does not change. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a structure of a light emitting device having a transistor. The invention is particularly applicable to glass,
The present invention relates to a structure of an active matrix type light emitting device having a thin film transistor (hereinafter referred to as a TFT) formed on an insulator such as plastic. In addition, the present invention relates to an electronic device using such a light emitting device in a display portion.

[0002]

2. Description of the Related Art In recent years, electroluminescence
The development of display devices using light emitting elements such as ro Luminescence (EL) elements has been activated. Since the light emitting element emits light by itself, the visibility is high, and the liquid crystal display device
Since it does not require a necessary backlight in (LCD) and the like, it is suitable for thinning, and there is almost no limitation on the viewing angle.

Here, the EL element refers to an element having a light emitting layer capable of obtaining luminescence generated by applying an electric field. In this light emitting layer, there are light emission when returning from the singlet excited state to the ground state (fluorescence) and light emission when returning to the ground state from the triplet excited state (phosphorescence), the light emitting device of the present invention, Any of the above-described light emission forms may be used.

The EL element is constructed such that a light emitting layer is sandwiched between a pair of electrodes (anode and cathode), and usually has a laminated structure. Typically, a laminated structure of “anode / hole transport layer / light emitting layer / electron transport layer / cathode” proposed by Tang et al. Of Eastman Kodak Company can be mentioned.
This structure has a very high luminous efficiency, and many EL devices currently under study employ this structure.

In addition to this, "hole injection layer / hole transport layer / light emitting layer / electron transport layer" is provided between the anode and the cathode.
Alternatively, there is a structure in which "hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer" are stacked in this order. As the structure of the EL element used in the light emitting device of the present invention, any of the structures described above may be adopted. Further, the light emitting layer may be doped with a fluorescent dye or the like.

In the present invention, in an EL element, all layers provided between an anode and a cathode are collectively called an EL layer. Therefore, the above hole injection layer, hole transport layer, light emitting layer, electron transport layer, and electron injection layer are all included in an EL device, and a light emitting device composed of an anode, an EL layer, and a cathode is referred to as an EL device. Call.

FIG. 3 shows the structure of a pixel in a general light emitting device. An EL display device is taken as an example of a typical light emitting device. The pixel shown in FIG. 3 has the source signal line 3
01, gate signal line 302, switching TFT 30
3, driving TFT 304, capacitance means 305, EL element 3
06, a current supply line 307, and a power supply 308.

The connection relation of each part will be described. Here, the TFT has three terminals of a gate, a source, and a drain. Regarding the source and the drain, due to the structure of the TFT,
I can't distinguish it clearly. Therefore, when the connection between the elements is described, one of the source and the drain is referred to as a first electrode and the other is referred to as a second electrode. TFT ON, OF
Regarding F, when it is necessary to explain the potential of each terminal (gate-source voltage of a certain TFT, etc.),
Indicated as drain, etc.

In the present invention, the fact that the TFT is turned on means that the gate-source voltage of the TFT exceeds its threshold value and a current flows between the source and drain, and the TFT is turned off. The state that the gate-source voltage of the TFT is lower than the threshold value and the current does not flow between the source and the drain.

The gate electrode of the switching TFT 303 is connected to the gate signal line 302, the first electrode is connected to the source signal line 301, and the second electrode is the driving TFT.
It is connected to the gate electrode of 304. Driving TFT3
The first electrode of 04 is connected to the current supply line 307, and the second electrode of 04 is connected to the first electrode of the EL element 306. The second electrode of the EL element 306 is connected to the power source 308. The capacitance means 305 is connected between the gate electrode of the driving TFT 304 and the first electrode, and is connected to the driving TF.
Holds the gate-source voltage of T304.

When the potential of the gate signal line 302 changes and the switching TFT 303 is turned on, the source signal line 3
The video signal input to 01 is the driving TFT 304.
Is input to the gate electrode of. The gate-source voltage of the driving TFT 304 is determined according to the potential of the input video signal, and the current flowing between the source and drain of the driving TFT 304 (hereinafter referred to as drain current) is determined.
This current is supplied to the EL element 306 to emit light.

By the way, a TFT formed of polycrystalline silicon (hereinafter referred to as P-Si) has a higher field effect mobility than a TFT formed of amorphous silicon (hereinafter referred to as amorphous silicon (A-Si)), and is turned on. Since the current is large, it is more suitable as a transistor used for a light emitting device.

On the other hand, a TFT made of polysilicon
Has a problem that variations in its electrical characteristics are likely to occur due to defects in crystal grain boundaries.

In the pixel shown in FIG. 3, when the characteristics such as the threshold value and ON current of the TFTs forming the pixel vary from pixel to pixel, the drain current of the TFT correspondingly changes even when the same video signal is input. The brightness of the EL element 306 varies because the size of the EL element 306 varies. Therefore, in the case of analog gradation, it has been a problem.

Therefore, by using a region where the threshold value of the TFT is unlikely to affect the ON current, the EL element is set to 100% luminance,
A digital gradation method has been proposed in which the driving is performed only in two states of 0%. With this method, only two gradations, white and black, can be expressed, so that multi-gradation is realized by combining with a time gradation method or the like.

The configuration of the pixel of the light emitting device in the case of using the method combining the digital gradation method and the time gradation method is as follows.
There is one as shown in FIGS. 4 (A) and 4 (B). In addition to the switching TFT 404 and the driving TFT 405, an erasing T
By using the FT406, the length of the light emission time can be finely controlled.

On the other hand, by using the analog gradation method, the TFT
There has been proposed a device capable of correcting the threshold variation (see, for example, Patent Document 1).

[0018]

[Patent Document 1] US Pat. No. 6,229,506

As shown in FIG. 5, source signal lines 501,
First to third gate signal lines 502 to 504, TFT 50
5 to 508, capacitor means 509 (C ₂ ), 510 (C ₁ ), a current supply line 512, and an EL element 511.

The gate electrode of the TFT 505 is connected to the first gate signal line 502, the first electrode is connected to the source signal line 501, and the second electrode is connected to the first electrode of the capacitance means 509. Has been done. The second electrode of the capacitance means 509 is connected to the first electrode of the capacitance means 510, and the second electrode of the capacitance means 510 is connected to the current supply line 512. The gate electrode of the TFT 506 is the capacitance means 50.
9 is connected to the second electrode and the first electrode of the capacitance means 510, the first electrode is connected to the current supply line 512,
The second electrode is the first electrode of the TFT 507 and the TFT.
508 is connected to the first electrode. The gate electrode of the TFT 507 is connected to the second gate signal line 503,
The second electrode is connected to the second electrode of the capacitance means 509 and the first electrode of the capacitance means 510. TFT50
The gate electrode of No. 8 is connected to the third gate signal line 504, and the second electrode is connected to the first electrode of the EL element 511. The power supply 5 is connected to the second electrode of the EL element 511.
A constant potential is applied by 13 and has a potential difference from the current supply line 512.

Using FIG. 5B and FIGS. 6A to 6F,
The operation will be described. FIG. 5B shows the source signal line 50.
1 shows timings of video signals and pulses input to the first to third gate signal lines 502 to 504,
It is divided into sections I to VIII according to each operation shown in FIG. Moreover, in the example of the pixel shown in FIG.
It is constructed using FT, and its polarity is all P-channel type. Therefore, when the L level is input to the gate electrode, it turns on
However, the H level is input and turned off.

First, the first gate signal line 502 becomes L level, and the TFT 505 is turned on (section I). Then, the second and third gate signal lines become L level, and the TFT 50
7,508 turn on. Here, as shown in FIG. 6A, the capacitance means 509, 510 are charged and the capacitance means 51
When the voltage held by 0 exceeds the threshold value (V _th ) of the TFT 506, the TFT 506 is turned on (section II).

Then, the third gate signal line becomes H level, and the TFT 508 is turned off. Then, the charges accumulated in the capacitor means 509 and 510 move again, and the voltage held in the capacitor means 510 eventually becomes equal to V _th . At this time, as shown in FIG. 6B, the current supply line 5
12. Since the potentials of the source signal line 501 and the source signal line 501 are all V _DD , the voltage held in the capacitance means 509 is equal to V _th . Therefore, the TFT 506 eventually becomes O.
FF.

As described above, when the voltage held in the capacitance means 509, 510 becomes equal to V _th , the second gate signal line 503 becomes H level and the TFT 50.
7 is turned off (section IV). By this operation, FIG. 6 (C)
As shown in, _Vth is held in the capacitance means.

At this time, regarding the charge Q ₁ held in the capacitance means 510 (C ₁ ), the relation as in the equation (1) is established. At the same time, in the electric charge Q ₂ held in the capacitance means 509 (C ₂ ), the relation as in the equation (2) is established.

[0026]

[Equation 1]

[0027]

[Equation 2]

Subsequently, as shown in FIG. 6D, a video signal is input (section V). Video signal to the source signal line 501 is output, the potential voltage V _{Da ta} of the video signal from V _DD (here, since TFT506 is a P-channel type, and V _DD> V _Data.) Become. T at this time
Assuming that the potential of the gate electrode of the FT 506 is V _P and the charge at this node is Q, the relations of formulas (3) and (4) are established by the charge conservation law including the capacitance means 509 and 510.

[0029]

[Equation 3]

[0030]

[Equation 4]

From the expressions (1) to (4), the potential V _P of the gate electrode of the TFT 506 is expressed by the expression (5).

[0032]

[Equation 5]

Therefore, the gate-source voltage V _GS of the TFT 506 is expressed by the equation (6).

[0034]

[Equation 6]

The right side of the equation (6) includes a term of V _th . That is, the threshold value of the TFT 506 in the pixel is added to the video signal input from the source signal line and is stored in the capacitor 510.

When the input of the video signal is completed, the first gate signal line 502 becomes H level and the TFT 505 becomes O.
FF is performed (section VI). After that, the source signal line returns to a predetermined potential (section VII). By the above operation, the writing operation of the video signal to the pixel is completed (FIG. 6E).

Then, the third gate signal line becomes L level, the TFT 508 is turned on, and a current flows through the EL element as shown in FIG. 6F, whereby the EL element emits light. At this time, the value of the current flowing through the EL element is
According to the gate-source voltage of 6, the TFT
Drain current I _DS flowing through 506 is represented by the formula (7).

[0038]

[Equation 7]

From equation (7), it can be seen that the drain current I _DS of the TFT 506 does not depend on the threshold value V _th . Therefore, even if the threshold value of the TFT 506 varies, by correcting the value for each pixel and adding it to the video signal, the current according to the potential V _Data of the video signal becomes E.
It can be seen that the current flows to the L element.

[0040]

However, in the case of the above configuration, if the capacitance values of the capacitance means 509, 510 vary, the drain current I _DS of the TFT 506 also varies. Therefore, in the present invention, by the structure that is not affected by the variation of the capacitance value, T
It is an object of the present invention to provide a light emitting device using a pixel having a configuration capable of correcting threshold variation of FT.

[0041]

According to the method described above, T
The drain current I _{DS of the} FT 506 is equal to the two capacitive means 50.
It depended on the capacity value of 9,510. That is, when the state where the threshold value is held (FIG. 6C) is shifted to the writing of the video signal (FIG. 6D), there is a movement of electric charge between the capacitance means C ₁ and C _2. . That is, the voltage between both electrodes of C ₁ and the voltage between both electrodes of C ₂ change in FIG. 6 (C) → FIG. 6 (D). At that time, if the capacitance values of C ₁ and C ₂ vary, the voltage between both electrodes of C ₁ and the voltage between both electrodes of C ₂ also vary. In the present invention, in the process of inputting the video signal after the threshold value is stored by using the capacitance means, there is no movement of electric charge in the capacitance means. Therefore, the voltage between both electrodes of the capacitance means does not change. Therefore, since the correction can be performed by directly adding the threshold value to the video signal, it is possible to prevent the drain current from being affected by the variation in the capacitance value.

Further, as the transistor in the present invention, the one mainly constituted by using the TFT is mentioned as an example, but a single crystal transistor or a transistor using an organic substance may be used. For example, the single crystal transistor can be a transistor formed using an SOI technique. Further, as the thin film transistor,
A polycrystalline semiconductor or an amorphous semiconductor may be used for the active layer. For example, a TFT using polysilicon or a TFT using amorphous silicon can be used. Alternatively, a bipolar transistor or a transistor formed of carbon nanotube or the like may be used.

The constitution of the present invention will be described below.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, and the pixel has at least a current supply line, first to fourth transistors, and a capacitance means. A gate electrode of the first transistor is electrically connected to a first electrode of the second transistor and a first electrode of the capacitance means, and the first electrode is electrically connected to the current supply line. The second electrode is electrically connected to the second electrode of the second transistor and the first electrode of the third transistor,
A first signal is input to the gate electrode of the second transistor, a second signal is input to the gate electrode of the third transistor, and a second electrode of the capacitance means is connected to the first electrode. Electrically connected to the first electrode of the fourth transistor, the third signal is input to the gate electrode of the fourth transistor, and the second electrode is electrically connected to the current supply line. It is characterized by having a different configuration.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a fifth transistor, a capacitor, and a light emitting element, and the gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Is electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor is electrically connected to the second gate signal line, and the second electrode is electrically connected to the current supply line. And the second electrode of the capacitance means is electrically connected to the first electrode of the third transistor and the gate electrode of the fifth transistor,
The gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor and the first electrode of the fifth transistor. Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the second electrode is electrically connected to the first electrode of the light emitting element. And a second electrode of the fifth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a fifth transistor, a capacitor, and a light emitting element, and the gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Is electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor is electrically connected to the second gate signal line, and the second electrode is electrically connected to the current supply line. And the second electrode of the capacitance means is electrically connected to the first electrode of the third transistor and the gate electrode of the fifth transistor,
A gate electrode of the third transistor is electrically connected to the second gate signal line, and a second electrode of the third transistor is the first electrode of the fourth transistor and the first electrode of the fifth transistor. Is electrically connected to the third electrode, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode is electrically connected to the first electrode of the light emitting element. And a second electrode of the fifth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a fifth transistor, a capacitor, and a light emitting element, and the gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
Is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the gate electrode of the second transistor is electrically connected to the second gate signal line. And the second electrode is connected to the fourth electrode.
Electrically connected to the first electrode of the fifth transistor and the first electrode of the fifth transistor, and the second electrode of the capacitance means includes the first electrode of the third transistor and the first electrode of the third transistor. 5 is electrically connected to the gate electrode of the transistor, and the gate electrode of the third transistor is
The second electrode is electrically connected to the third gate signal line, the second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the fourth electrode is electrically connected to the second electrode of the fifth transistor.
The gate electrode of the transistor is electrically connected to the fourth gate signal line, and the second electrode is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a fifth transistor, a capacitor, and a light emitting element, and the gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
Is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the gate electrode of the second transistor is electrically connected to the second gate signal line. And the second electrode is connected to the fourth electrode.
Electrically connected to the first electrode of the fifth transistor and the first electrode of the fifth transistor, and the second electrode of the capacitance means includes the first electrode of the third transistor and the first electrode of the third transistor. 5 is electrically connected to the gate electrode of the transistor, and the gate electrode of the third transistor is
The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the fourth electrode is electrically connected to the second electrode of the fifth transistor.
The gate electrode of the transistor is electrically connected to the third gate signal line, and the second electrode is electrically connected to the current supply line.

A light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fifth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Is electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor is electrically connected to the second gate signal line, and the second electrode is electrically connected to the current supply line. And the second electrode of the capacitance means is electrically connected to the first electrode of the third transistor and the gate electrode of the fifth transistor,
The gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor and the first electrode of the fifth transistor. Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the second electrode is electrically connected to the first electrode of the light emitting element. And a second electrode of the fifth transistor electrically connected to the current supply line,
The gate electrode of the sixth transistor is electrically connected to the fifth gate signal line, and the first electrode is the first electrode of the third transistor or the second electrode of the third transistor. It is characterized in that it is electrically connected to the electrode of.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Is electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor is electrically connected to the second gate signal line, and the second electrode is electrically connected to the current supply line. And the second electrode of the capacitance means is electrically connected to the first electrode of the third transistor and the gate electrode of the fifth transistor,
A gate electrode of the third transistor is electrically connected to the second gate signal line, and a second electrode of the third transistor is the first electrode of the fourth transistor and the first electrode of the fifth transistor. Is electrically connected to the third electrode, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode is electrically connected to the first electrode of the light emitting element. And a second electrode of the fifth transistor electrically connected to the current supply line,
The gate electrode of the sixth transistor is electrically connected to the fourth gate signal line, and the first electrode is the first electrode of the third transistor or the second electrode of the third transistor. It is characterized in that it is electrically connected to the electrode of.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor. Is electrically connected to the second electrode of the fifth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the second electrode is The second electrode of the sixth transistor is electrically connected to the first electrode of the light emitting element, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the second transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the first electrode of the fourth transistor. Is electrically connected to the second electrode of the fifth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode is The second electrode of the sixth transistor is electrically connected to the first electrode of the light emitting element, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor. Is electrically connected to the second electrode of the fifth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the second electrode is The second electrode of the sixth transistor is electrically connected to the first electrode of the light emitting element, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the second transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the first electrode of the fourth transistor. Is electrically connected to the second electrode of the fifth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode is The second electrode of the sixth transistor is electrically connected to the first electrode of the light emitting element, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the first electrode of the fourth transistor is electrically connected to the second electrode of the sixth transistor. The second electrode is electrically connected and is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the first electrode of the fourth transistor is electrically connected to the second electrode of the sixth transistor. The second electrode is electrically connected and is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to a first electrode of the second transistor, a gate electrode of the second transistor electrically connected to the second gate signal line, and a second electrode of the fourth transistor. The first electrode is electrically connected to the first electrode of the fifth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, a gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and a second electrode of the fourth transistor is electrically connected to the first electrode of the sixth transistor. It is electrically connected, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, and a current supply line. A first to a sixth transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to a first electrode of the second transistor, a gate electrode of the second transistor electrically connected to the second gate signal line, and a second electrode of the fourth transistor. The first electrode is electrically connected to the first electrode of the fifth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode of the fourth transistor is electrically connected to the first electrode of the sixth transistor. It is electrically connected, and the second electrode of the sixth transistor is electrically connected to the current supply line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fifth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and the first electrode of the fourth transistor is electrically connected to the second electrode of the sixth transistor. Electrically, the second electrode is electrically connected to the current supply line, and the gate electrode of the seventh transistor is electrically connected to the fifth gate signal line. The electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to the first electrode of the second transistor, the gate electrode of the second transistor electrically connected to the second gate signal line, and the second electrode of the fifth transistor. The first electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the first electrode of the fourth transistor is electrically connected to the second electrode of the sixth transistor. Electrically, the second electrode is electrically connected to the current supply line, and the gate electrode of the seventh transistor is electrically connected to the fourth gate signal line. The electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fifth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to a first electrode of the second transistor, a gate electrode of the second transistor electrically connected to the second gate signal line, and a second electrode of the fourth transistor. The first electrode is electrically connected to the first electrode of the fifth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, a gate electrode of the fourth transistor is electrically connected to the fourth gate signal line, and a second electrode of the fourth transistor is electrically connected to the first electrode of the sixth transistor. Electrically connected, the second electrode of the sixth transistor is electrically connected to the current supply line, and the gate electrode of the seventh transistor is electrically connected to the fifth gate signal line. It is characterized in that the first electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
The electrodes of the first and the second electrodes of the capacitance means.
Electrically connected to a first electrode of the second transistor, a gate electrode of the second transistor electrically connected to the second gate signal line, and a second electrode of the fourth transistor. The first electrode is electrically connected to the first electrode of the fifth transistor, and the second electrode of the capacitance means is the first electrode of the third transistor and the fifth electrode. The gate electrode of the
Is electrically connected to the gate electrode of the third transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the second electrode of the fifth transistor. And an electrode of the light emitting device
Of the fourth transistor, the gate electrode of the fourth transistor is electrically connected to the third gate signal line, and the second electrode of the fourth transistor is electrically connected to the first electrode of the sixth transistor. Electrically, the second electrode of the sixth transistor is electrically connected to the current supply line, and the gate electrode of the seventh transistor is electrically connected to the fourth gate signal line. It is characterized in that the first electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fifth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
Is electrically connected to the first electrode of the second transistor, the first electrode of the sixth transistor, and the first electrode of the capacitance means, and the gate of the second transistor The electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is of the third transistor. The first electrode is electrically connected to the gate electrode of the fifth transistor, the gate electrode of the sixth transistor and the second electrode, and the gate electrode of the third transistor is connected to the third electrode. The second electrode is electrically connected to the gate signal line, and the second electrode is electrically connected to the first electrode of the fourth transistor and the first electrode of the fifth transistor. The gate electrode of the Of the gate signal line electrically connected to, the second electrode is a first electrode electrically connected to the light emitting element, a second electrode of said fifth transistor,
The seventh transistor is electrically connected to the current supply line, and the seventh transistor is provided between the second electrode of the first transistor and the first electrode of the sixth transistor and between the second electrode of the third transistor and the third electrode of the third transistor. Between the first electrode and the second electrode of the sixth transistor, or the first electrode of the third transistor.
Is provided between the second electrode and the gate electrode of the sixth transistor, and the gate electrode is electrically connected to the fifth gate signal line.

The light emitting device of the present invention is a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to fourth gate signal lines, and a current supply line. A first to a seventh transistor, a capacitor, and a light emitting element, and a gate electrode of the first transistor is electrically connected to the first gate signal line;
The electrode of is electrically connected to the source signal line,
Is electrically connected to the first electrode of the second transistor, the first electrode of the sixth transistor, and the first electrode of the capacitance means, and the gate of the second transistor The electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is of the third transistor. The first electrode is electrically connected to the gate electrode of the fifth transistor, the gate electrode of the sixth transistor and the second electrode, and the gate electrode of the third transistor is electrically connected to the second electrode. The second electrode is electrically connected to the gate signal line, and the second electrode is electrically connected to the first electrode of the fourth transistor and the first electrode of the fifth transistor. The gate electrode of the Of the gate signal line electrically connected to, the second electrode is a first electrode electrically connected to the light emitting element, a second electrode of said fifth transistor,
The seventh transistor is electrically connected to the current supply line, and the seventh transistor is provided between the second electrode of the first transistor and the first electrode of the sixth transistor and between the second electrode of the third transistor and the third electrode of the third transistor. Between the first electrode and the second electrode of the sixth transistor, or the first electrode of the third transistor.
Is provided between the second electrode and the gate electrode of the sixth transistor, and the gate electrode is electrically connected to the fourth gate signal line.

In the light emitting device of the present invention, the second transistor and the third transistor may have the same polarity.

In the light emitting device of the present invention, the gate length of the fifth transistor is L ₁ , the channel width is W ₁ ,
When the gate length of the sixth transistor is L ₂ and the channel width is W ₂ , (W ₁ / L ₁ )> (W ₂ / L ₂ ) is included.

In the light emitting device of the present invention, the gate length of the fifth transistor is L ₁ , the channel width is W ₁ ,
When the gate length of the sixth transistor is L ₂ and the channel width is W ₂ , (W ₁ / L ₁ ) <(W ₂ / L ₂ ) is included.

In the light emitting device of the present invention, the second electrode of the sixth transistor is any one of the power supply line having a potential difference from the current supply line or the gate signal line for controlling the pixel. May be electrically connected to the gate signal line.

In the light emitting device of the present invention, the second electrode of the seventh transistor is any one of the power supply line having a potential difference from the current supply line or the gate signal line for controlling the pixel. May be electrically connected to the gate signal line.

The light emitting device of the present invention is the second light emitting device of the above
The electrode may be electrically connected to a power supply line having a potential difference with the current supply line.

In the light emitting device of the present invention, the pixel has a storage capacitor means, and the first electrode of the storage capacitor means is electrically connected to the second electrode of the first transistor, It is characterized in that a constant potential is applied to the second electrode and holds the video signal input from the source signal line in the previous period.

A driving method of a light emitting device of the present invention is a driving method of a light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, a current supply line, and a desired light emitting element. A first step, which includes at least a transistor for supplying a current, a light emitting element, and a capacitance means, stores a charge in the capacitance means; A second step of converging to a voltage equal to the voltage; a third step of inputting a video signal from the source signal line; A fourth step of applying a current to the light emitting element through the transistor to emit light, and at least in the third step, between both electrodes of the capacitance means. The voltage is constant, at least the first and second step, the first transistor is characterized in that a non-conductive state.

A method of driving a light emitting device according to the present invention is a method of driving a light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a current supply line, first to third transistors, and a capacitor. Means, the gate electrode of the first transistor is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the first electrode is The second electrode is electrically connected to the current supply line, the second electrode is electrically connected to the second electrode of the second transistor and the first electrode of the third transistor, and the second electrode is electrically connected to the second electrode of the second transistor. A first signal is input from the gate electrode of the transistor, a second signal is input from the gate electrode of the third transistor, and a second electrode of the capacitance means is the first electrode of the fourth transistor.
A video signal is input from the second electrode of the capacitance means, a third signal is input from the gate electrode of the fourth transistor, and the second electrode is A first step of being electrically connected to the current supply line, inputting the first to third signals to turn on the second to fourth transistors, and accumulating electric charges in the capacitance means; , The third transistor is made non-conductive, and the first and third signals are input to make the second and fourth transistors conductive, thereby making the voltage held in the capacitance means The second step of converging to a value equal to the threshold voltage of the first transistor, turning off the second to fourth transistors, and inputting the video signal from the second electrode of the capacitance means. The third step, Serial second, by the fourth transistor is non-conductive, and to conduct the Enter the second signal a third transistor, the first, third
And a fourth step in which a current flows between the source and drain of the transistor, and the voltage between both electrodes of the capacitance means is constant in at least the third step.

[0074]

DETAILED DESCRIPTION OF THE INVENTION FIG. 1A shows an embodiment of the present invention. Source signal line 101, first to fourth gate signal lines 102 to 105, first to fifth TFTs 106 to 11
0, first and second capacitance means 111 and 115, an EL element 112, a current supply line 113, and a power supply 114.

The gate electrode of the first TFT 106 is the first
Connected to the gate signal line 102, the first electrode is connected to the source signal line 101, and the second electrode is connected to the second TF.
It is connected to the first electrode of T107. Second TFT
The gate electrode of 107 is connected to the second gate signal line 103, and the second electrode is connected to the current supply line 113. The first electrode of the first capacitance means 111 has a second T
The second electrode is connected to the first electrode of the FT 107, and the second electrode is connected to the first electrode of the third TFT 108. Third
The gate electrode of the TFT 108 is the third gate electrode 10
4 and the second electrode is connected to the first electrode of the fourth TFT 109. The gate electrode of the fourth TFT 109 is connected to the fourth gate signal line 105,
The electrode of is connected to the first electrode of the EL element 112. The gate electrode of the fifth TFT 110 is the third TFT
Connected to the first electrode of the first capacitor means 108 and the second electrode of the first capacitance means 111, and the first electrode is connected to the third TFT 10;
8 is connected to the second electrode and the first electrode of the fourth TFT 109, and the second electrode is connected to the current supply line 113. The second capacitance means 115 is the first TFT1.
It is arranged between the second electrode 06 and the current supply line 113, and holds the potential of the video signal input from the source signal line 101. The second capacitance means 115 can be operated without any particular provision. A constant potential is applied to the second electrode of the EL element 112 by the power supply 114, and there is a potential difference from the current supply line 113.

Using FIG. 1B and FIGS. 2A to 2F,
The operation will be described. FIG. 1B shows the source signal line 10
1 shows timings of video signals and pulses input to the first to fourth gate signal lines 102 to 105,
In accordance with each operation shown in FIG. 2, it is divided into sections I to VI. In addition, in the configuration shown in FIG.
The third TFTs 106 to 108 are N-channel type and the fourth T-type.
The FT 109 and the fifth TFT 110 are P-channel type. As shown in FIG. 5A, although it is possible to use all P-channel type TFTs, the first TFT 106 to the third TFT 108 are N-channel type here. In the N-channel TFT, the H level is input to the gate electrode to turn it on, and the L level is input to turn it off. In the P-channel TFT, the L level is input to the gate electrode to turn it on,
The H level is input and turned off.

For the sake of simplicity, the second capacitance means 115
Are omitted in FIGS. 2 (A) to 2 (F).

First, the second and third gate signal lines 103,
104 is at H level, the fourth gate signal line 105 is at L level, and the TFTs 107 to 109 are turned on (section I).
As a result, a current as shown in FIG. 2A is generated and the capacitance means 111 is charged. When the voltage held by the capacitor means 111 exceeds the threshold value (V _th ) of the TFT 110, the TFT 110 turns on.

After that, the fourth gate signal line 105 becomes H level, and the TFT 109 is turned off (section II). As a result, the current path between the current supply line 113 and the EL element 112 is closed, and the current is stopped. On the other hand, as shown in FIG. 2, the charges accumulated in the capacitance means 111 start moving again. The voltage between both electrodes of the capacitance means 111 is
Since this is the gate-source voltage of the TFT 110, the TFT 110 becomes OF when the voltage becomes equal to V _th.
Then, the transfer of electric charges is completed (FIG. 2 (B)).

After that, the second and third gate signal lines 10
3 and 104 are all at the L level, and the TFT 107,
108 turns off. Therefore, the capacitor 111 holds the threshold voltage of the TFT 110, as shown in FIG.

Then, the first gate signal line 102 becomes H level, and the TFT 106 is turned on (section IV). The source signal line 101, and the image is output signal, in that potential V _{D D} from the video signal potential V _Data (here, TFT 1
Since 10 is a P-channel type, V _DD > V _Data . ). Here, since the previous V _th is held as it is in the capacitor means 111, the TFT 110
The potential of the gate electrode is a potential obtained by adding a threshold value V _th to the video signal potential V _Data input from the source signal line 101. Therefore, the TFT 110 is turned on (Fig. 2
(D)).

When the writing of the video signal is completed,
The first gate signal line 102 becomes L level, and the TFT1
06 is turned off (section V). After that, the output of the video signal to the source signal line is also completed, and the potential returns to V _DD (see FIG. 2).
(E)).

Subsequently, the fourth gate signal line 105 becomes L level, and the TFT 109 is turned on (section VI). TF
Since T110 is already turned on, the EL element 112 emits light when a current flows from the current supply line 113 to the EL element 112 (FIG. 2 (F)). At this time, the EL element 11
The value of the current flowing in 2 is according to the gate-source voltage of the TFT 110, and the gate-source voltage of the TFT 110 at this time is (V _DD − (V _Data + V _th )). Here, even if the threshold value V _{th of} the TFT 110 varies from pixel to pixel, a voltage corresponding to the variation is held in the capacitance means 111 of each pixel. Therefore, E
The brightness of the L element 112 is not affected by the variation in threshold value.

By the above-described operation, the light emission is performed from the writing of the video signal. In the present invention, the capacitance means 1
By capacitive coupling of 11, the potential of the video signal is
It can be offset by a threshold value of 10. Therefore, as described above, the threshold value can be accurately corrected without being affected by the characteristic variations of other elements.

FIGS. 26 (A) and 26 (B) are views for briefly explaining the threshold correction operation in the conventional example and the present invention. Figure 2
In 6 (A), when a video signal is input, electric charge is stored between the two capacitance means C ₁ and C ₂ and movement of electric charge occurs. Therefore, between the gate and source of the TFT that supplies a current to the EL element. The voltage V _GS is represented by an equation including the capacitance values C ₁ and C ₂ in the term, as shown in (iii) of FIG. Therefore,
When the capacitance values C1 and C2 vary, the gate-source voltage of the TFT also varies.

On the other hand, in the case of the present invention, the electric charge is stored in the capacitance means.
As shown in (iii) of (B), charge transfer does not occur. That is, since the potential obtained by adding the threshold voltage to the potential of the video signal is applied to the gate electrode of the TFT as it is, the voltage between the gate and the source of the TFT can be made less likely to vary.

The pixel selection timing, that is, the timing at which a video signal is written to a certain pixel depends on the signal input timing to the source signal line 101 and the selection timing of the first gate signal line 102. That is, operations such as initialization of a certain pixel and charging of the capacitor can be performed independently of the timing of writing the video signal. Since these operations may be performed in a plurality of rows in parallel, the selection timings of the second to fourth gate signal lines in different rows may overlap. Therefore, the period indicated by * in FIG. 1B, that is, the period for performing the operation of storing the threshold voltage can be long.

Further, in FIG. 1A, the arrangement of the TFT 109 may be changed to have a structure as shown in FIG. The numbers attached to the figure are the same as those in FIG.
The TFT 109 is connected between the first electrode of the TFT 110 and the EL element 112, the second electrode of the TFT 110 and the TF.
It is moved between the second electrode of T107 and the current supply line 113.

Note that the polarity of the TFT in the structure shown in this embodiment is merely an example, and the polarity is not limited.

In the embodiment of the present invention shown in FIG. 1, the control is performed by using four gate signal lines per pixel, but it is controlled by the second and third gate signal lines 103 and 104. Since the operation timings of the TFTs 107 and 108 are the same as shown in FIG.
If the polarities of 7 and 108 are the same, the number of gate signal lines can be reduced by controlling them by the same gate signal line. In this case, the aperture ratio can be increased.

[0091]

EXAMPLES Examples of the present invention will be described below.

[Embodiment 1] In this embodiment, a configuration of a light emitting device that performs display by using an analog video signal as a video signal will be described. FIG. 7A shows a structural example of a light emitting device. A pixel portion 702 in which a plurality of pixels are arranged in matrix is provided on a substrate 701, and a source signal line driver circuit 703 and first to fourth gate signal line driver circuits 704 to 707 are provided around the pixel portion. have. In FIG. 7A, four sets of gate signal line driver circuits are used to control the first to fourth gate signal lines in the pixel shown in FIG. 1, respectively.

Source signal line drive circuit 703, first to third
The signals input to the gate signal line drive circuits 704 to 706 of the
It is supplied from the outside via uit: FPC) 708.

FIG. 7B shows a configuration example of the source signal line driver circuit. This is a source signal line driver circuit for performing display by using an analog video signal as a video signal, and includes a shift register 711, a buffer 712, and a sampling circuit 713. Although not particularly shown, a level shifter or the like may be added if necessary.

The operation of the source signal line drive circuit will be described. Since a more detailed structure is shown in FIG. 8A, reference will be made there.

The shift register 801 includes a plurality of flip-flop circuits (FF) 802 and the like, and receives a clock signal (S-CLK), a clock inversion signal (S-CLKb), and a start pulse (S-SP). It Sampling pulses are sequentially output in accordance with the timing of these signals.

The sampling pulse output from the shift register 801 is amplified through the buffer 803 and the like, and then input to the sampling circuit. The sampling circuit 804 includes a plurality of stages of sampling switches (SW) 805, and samples a video signal in a certain column in accordance with the timing of inputting a sampling pulse. Specifically, when a sampling pulse is input to the sampling switch, the sampling switch 805 is turned on, and the potential of the video signal at that time is output to each source signal line through the sampling switch.

Next, the operation of the gate signal line drive circuit will be described. A detailed configuration of the first and second gate signal line driver circuits 704 and 705 and the third and fourth gate signal line driver circuits 706 and 707 illustrated in FIG. 7C is illustrated in FIG. It was shown to. The first gate signal line driver circuit includes a shift register circuit 811, a buffer 812, a clock signal (G-CLK1), and a clock inversion signal.
(G-CLKb1) and start pulse (G-SP1). The second gate signal line driver circuit includes a shift register circuit 813 and a buffer 814, and includes a clock signal (G-CLK2) and a clock inversion signal (G-CLKb).
2), driven according to the start pulse (G-SP2).

The operation of the shift register to the buffer is the same as that of the source signal line drive circuit. The selection pulse amplified by the buffer selects each gate signal line. The first gate signal line driving circuit sequentially selects the first gate signal lines G ₁₁ , G ₂₁ , ..., G _m1 , and the second gate signal line driving circuit selects the second gate signal line G 1. ₁₂ , G ₂₂ , ..., G _m2 are sequentially selected. Although not shown, the third gate signal line drive circuit is similar to the first and second gate signal line drive circuits, and the third gate signal line G ₁₃ , G ₂₃ , ..., G _m3.
Are sequentially selected. In the selected row, the video signal is written in the pixel to emit light by the procedure described in the embodiment.

Here, as an example of the shift register, the one using a plurality of stages of flip-flops is shown, but a signal line may be selected by a decoder or the like.

[Embodiment 2] In this embodiment, a configuration of a light emitting device that performs display by using a digital video signal as a video signal will be described. FIG. 9A shows a structural example of a light emitting device. A pixel portion 902 in which a plurality of pixels are arranged in matrix is provided over a substrate 901, and a source signal line driver circuit 903 and first to fourth gate signal line driver circuits 904 to 907 are provided around the pixel portion. have. In FIG. 9A, four sets of gate signal line driver circuits are used to control the first to fourth gate signal lines in the pixel shown in FIG. 1, respectively.

Source signal line drive circuit 903, first to fourth
The signals input to the gate signal line drive circuits 904 to 907 of the
It is supplied from outside via uit: FPC) 908.

FIG. 9B shows a configuration example of the source signal line driver circuit. This is a source signal line driver circuit for performing display using a digital video signal as a video signal, and includes a shift register 911, a first latch circuit 912, a second latch circuit 913, and a D / A conversion circuit 914. Have
Although not particularly shown, a level shifter or the like may be added if necessary.

First to fourth gate signal line drive circuits 904
Since the items from to 907 may be the same as those shown in the first embodiment, their illustration and description are omitted here.

The operation of the source signal line driver circuit will be described. A more detailed structure is shown in FIG. 10A, which will be referred to.

The shift register 1001 includes a plurality of stages of flip-flop circuits (FF) 1010 and the like, and has a clock signal (S-CLK) and an inverted clock signal (S-CLK).
b), the start pulse (S-SP) is input. Sampling pulses are sequentially output in accordance with the timing of these signals.

The sampling pulse output from the shift register 1001 is input to the first latch circuit 1002. A digital video signal is input to the first latch circuit 1002, and each stage holds the digital video signal in accordance with the timing of input of a sampling pulse. Here, the digital video signal is inputted in 3 bits, and the video signal of each bit is held in each of the first latch circuits. With one sampling pulse, the three first latch circuits operate in parallel here.

When the holding of the digital video signal is completed up to the final stage in the first latch circuit 1002, the second latch circuit 1003 receives the latch pulse during the horizontal blanking period.
(Latch Pulse) is input, and the digital video signals held in the first latch circuit 1002 are simultaneously transferred to the second latch circuit 1003. After that, the digital video signals held in the second latch circuit 1003 are input to the D / A conversion circuit 1004 for one row at the same time.

While the digital video signal held in the second latch circuit 1003 is input to the D / A conversion circuit 1004, the shift register 901 outputs the sampling pulse again. After that, repeat this operation,
The video signal for one frame is processed.

In the D / A conversion circuit 1004, the input digital video signal is digital-analog converted,
A video signal having an analog voltage is output to the source signal line.

The above operation is simultaneously performed in all stages within one horizontal period. Therefore, the video signal is output to all the source signal lines.

As described in the first embodiment,
A decoder or the like may be used instead of the shift register so that the signal line can be selected.

[Third Embodiment] In the second embodiment, a digital video signal is subjected to digital-analog conversion by a D / A conversion circuit and written into a pixel. You can also perform key expression. In this case, as shown in FIG. 10B, the D / A conversion circuit is not required and the gradation expression is controlled by the length of the light emission time of the EL element. Since it is not necessary to process the data, the first and second latch circuits may be one bit. At this time, in the digital video signal, each bit is serially input, sequentially held in the latch circuit, and written in the pixel.

Further, in the case of performing gradation expression by the time gradation method, the fourth TFT 109 in FIG.
It can be used as an FT. In this case, the fourth TF
T109 needs to be turned off throughout the erase period, and for that purpose, the fourth gate signal line 105 is controlled using the erase gate signal line drive circuit. Normally, in the case of a gate signal line drive circuit that selects a gate signal line, 1
Outputs one or more pulses in the horizontal period,
In the case of the erase gate signal line drive circuit, an independent drive circuit is used because the fourth TFT 109 must be continuously turned off during the erase period.

FIG. 24 shows an example of the time gray scale method. FIG. 24A is a timing chart for obtaining a 4-bit gradation, which includes address (writing) periods Ta1 to Ta4 of each bit and sustain (light emitting) periods Ts1 to T4.
s4 and erase periods Te1 to Te4.

Since the address (writing) period is a period required for the operation of inputting the video signal to the pixels for one screen,
Each bit is of equal length. In contrast, sustain
The length of the (light emission) period is 1: 2: 4: ...: 2.
^The gradation is expressed by the ratio of ^(n-1) to a power of 2, and the total of the light emitting periods. In the example of FIG. 24A, since it is 4 bits, the length of the sustain (light emission) period is 1:
It is 2: 4: 8.

Regarding the erase period, originally, the sustain
When the (light emission) period is short, the address (write) period is overlapped and different gate signal lines are not selected at the same time.

FIG. 24 (B) shows the timing of the pulse input to the first gate signal line in FIG. The period in which the gate signal lines are selected from the first row to the last row corresponds to the address (write) period.

FIG. 24C shows the timing of the pulses input to the second and third gate signal lines in FIG. Here, the second and third gate signal lines are commonly driven. Here, the period of H level is the period for storing the threshold value, and is performed before the address period in each subframe period.

FIG. 24D shows the timing of the pulse input to the fourth gate signal line in FIG. The period indicated by 2401 is the light emission period. That is, the erase period is provided by inputting the H level to the fourth gate signal line. In the period indicated by 2402, when the threshold value storage operation is performed, the L level is input because the TFT 109 needs to be turned on in this period as described in FIG.

In FIG. 24, the threshold value is stored during the erasing period, but light may be emitted during this period. In other words, the upper bits may not necessarily be provided with the erasing period and the threshold value may be stored during the sustain (light emitting) period.

The pulses shown in FIGS. 24B and 24C can be easily produced by the configuration of the conventional gate signal line drive circuit, but the pulse shown in FIG. 24D requires some improvement. Becomes In this embodiment, as shown in FIG. 25A, the gate signal line driver circuit has a two-phase structure, and as shown in FIG.
A circuit is used to combine and obtain the desired pulse.

Example 4 In the light emitting device introduced so far, in order to control the first to fourth gate signal lines,
This is done by operating each of the first to fourth gate signal line drive circuits. The merit of such a configuration is that the selection timing of each gate signal line can be changed independently, so that various driving methods can be supported to some extent. On the other hand, since the area occupied by the drive circuit in the substrate increases, there is a demerit that the periphery of the display area becomes large, that is, it is difficult to narrow the frame.

FIG. 11A shows a structural example for solving such a problem. In FIG. 11A, a shift register 1111 and a buffer 1112 are included, which is similar to the gate signal line driver circuit used in another embodiment. However, in this embodiment, a pulse division circuit 1113 is provided after the buffer. Added. The detailed structure is shown in FIG.

The pulse division circuit 1113 is the NAND 11
16 and a plurality of inverters 1117 are used. NAND of buffer output and externally input division signal (MPX)
Thus, one gate signal line drive circuit can control two gate signal lines controlled by different pulses. In the case of FIG. 11, the first gate signal line and the second gate signal line are controlled by one gate signal line drive circuit.

FIG. 12 shows the division signal (MPX) and the selection timing of each gate signal line. ₁₁ , G ₂₁ ,
.., G _m1 uses the buffer output as it is as a selection pulse. On the other hand, when the buffer output is at the H level and the divided signal is at the H level, the NAND output is at the L level, and the H level is output via the inverter.
₁₂ , G ₂₂ , ..., G _m2 are selected by this pulse.

[Embodiment 5] In the present invention, EL is emitted during light emission.
The TFT for supplying a current to the element (TFT 106 in FIG. 1A) is preferably operated in a saturation region in order to suppress variation in luminance due to deterioration of the EL element. At this time, the current in the saturation region is the TFT 106.
The gate length L is increased so that the source-drain voltage becomes almost constant even if the voltage changes.

At this time, in the operation of holding the threshold value in the capacitor means, the voltage once exceeding the threshold value of the TFT is applied to the capacitor means, and the threshold voltage is converged from that state. If the gate length L of the TFT is large, this operation requires time due to the gate capacitance and the like. Therefore, in the present embodiment, a configuration for realizing high speed operation in such a case will be described.

FIG. 18A shows a pixel structure. Figure 1
TFTs 1817, 1818, and a fifth gate signal line 1816 for controlling the TFT 1818 are added to the pixel shown in FIG. Further, as shown by a dotted line in FIG. 18A, the capacitor means 1815 may be provided between the second electrode of the TFT 1806 and the current supply line 1813 and used as a capacitor for holding a video signal. .

The operation will be described with reference to FIGS. 18B and 19A to 19F. FIG. 18B shows a source signal line 1801, first to fifth gate signal lines 1802 to 18
The timings of the video signals and pulses input to the channels 05 and 1816 are shown, and they are divided into sections I to VI in accordance with each operation shown in FIG. Since this embodiment is intended to speed up the operation until the threshold voltage is held in the capacitor means, the scraping of the video signal and the light emitting operation are the same as those described in the embodiment. Therefore, here, only the charge and hold operation of the electric charge in the capacitor means will be described.

First, the second, third, and fifth gate signal lines 1803, 1804, and 1816 are at the H level, the fourth gate signal line 1805 is at the L level, and the TFT 180
7, 1808, 1809, 1818 are turned on (section
I). As a result, a current as shown in FIG.
The capacity means 1811 is charged. The voltage held by the capacitance means 1811 is the threshold value of the TFTs 1810 and 1817.
When it exceeds (V _th ), the TFTs 1810 and 1817
Is turned on (FIG. 19 (A)).

Then, the fourth gate signal line 1805 goes high.
The level is turned on, and the TFT 1809 is turned off (section II).
As a result, the current path between the current supply line 1813 and the EL element 1812 is closed, and the current is stopped. On the other hand, FIG.
As shown in FIG. 9 (B), the electric charge stored in the capacitance means 1811 starts moving again. Since the voltage between both electrodes of the capacitance means 1811 is the gate-source voltage of the TFTs 1810 and 1817, the TFTs 1810 and 1817 are turned off when the voltage becomes equal to _Vth, and the transfer of electric charges is completed.

When the storage of the threshold value is completed in the capacitor 1811, the second and fifth gate signal lines become L level and the third gate signal line becomes H level, and the TFT 18
07, 1808, and 1818 are turned off (section III).

Then, the first gate signal line 1802 goes high.
The level is turned on, and the TFT 1806 is turned on (section IV).
A video signal is output to the source signal line 1801, and the potential thereof is from V _DD to the potential V _{Data of the} video signal (here, T _Data ).
Since the FT 110 is a P-channel type, V _DD > V _Data . ). Here, in the capacitance means 1811, since the previous V _th is held as it is, the TFT
The potentials of the gate electrodes 1810 and 1817 are the potentials obtained by adding the threshold value V _th to the video signal potential V _Data input from the source signal line 1801. Therefore, TFT18
10, 1817 are turned on (FIG. 19 (D)).

When writing of the video signal is completed,
The first gate signal line 1802 goes low and the TFT
1806 is turned off (section V). After that, the output of the video signal to the source signal line 1801 is completed and the potential is V _DD
Return to FIG. 19 (E).

Then, the fourth gate signal line 1805 goes low.
The level is turned on and the TFT 1809 is turned on (section VI).
Since the TFT 1810 has already been turned on, the current supply line 1
A current flows from 813 to the EL element 1812, so that the EL element 1812 emits light (FIG. 19F). At this time, the value of the current flowing through the EL element 1812 is
The gate-source voltage of the TFT 1810 at this time is (V _DD
− (V _Data + V _th )). Here, if the TFT 181
Even if the threshold value V _{th of} 0 varies among the pixels, the voltage corresponding to the variation causes the capacitance means 1811 of each pixel.
Held in. Therefore, the brightness of the EL element 1812 is not affected by the variation in the threshold value.

Here, the newly added TFT 1817
Are connected to the TFT 1810 for supplying a current to the EL element 1813 at the time of light emission, and to each other's gate electrodes. As shown in FIGS. 19A and 19B, the number of paths through which charges move is greater than that in the embodiment, and the TFT 1817 is
Since it does not have a role of supplying a current to the element 1812, the gate length L may be small and the channel width W may be large.
Therefore, since the gate capacitance is small, the charge can be smoothly moved, and the time required for the voltage held in the capacitance means to converge to V _th can be further shortened.

[Embodiment 6] In this embodiment, Embodiment 5
An example in which a high-speed threshold value saving operation is realized by a configuration different from

The structure is shown in FIG. Here, the TFT that stores the threshold value in the capacitor 2211 is TF.
It corresponds to T2210. When the EL element 2212 emits light, the TFT 2216, the TFT 2210, the TFT 2209
Current is supplied via. Here, the TFT 2209
Need only function as a switching element. E
To cope with the deterioration of the L element 2212, the TFT 2216
Operates in the saturation region, and increases the gate length L so that the drain current becomes substantially constant even if the source-drain voltage changes in the saturation region.

Charging is performed by the current path shown in FIGS. 22B to 22C, and the capacitance means 2211 is charged. After that, when the TFT 2209 is turned off, FIG.
As shown in FIG. 2 (C), the movement of charges occurs again, and when the voltage held in the capacitor 2211 becomes equal to the threshold values of the TFT 2210 and the TFT 2216,
The TFTs 2210 and 2216 are turned off. By this operation, the threshold value is stored in the capacity means 2211.
At this time, since the gate length L of the TFT 2210 is made small, the operation of FIG. 22C can proceed more quickly.

After that, as in the embodiment and other examples,
After writing the video signal, as shown in FIG. 22D, when the TFT 2209 is turned on, the current supply line-TFT
A current is supplied to the EL element 2212 via the 2216-TFT 2210-TFT 2209 to emit light.

At this time, since the gate electrodes of the TFTs 2210 and 2216 are connected to each other, the TFTs 2210 and 2216 operate as a multi-gate type TFT. At this time, TFT2
The gate length of 210 is L ₁ , the channel width is W ₁ , and the TFT
If the gate length of 2216 is L ₂ and the channel width is W ₂ ,
(W ₁ / L ₁ )> (W ₂ / L ₂ ). That is, in the threshold storage operation, the storage of the threshold voltage as shown in FIG. 22C uses the TFT 2210 having a small L and a large W, so that the operation can be completed with a larger current. That is, quick operation can be performed. And when emitting light, T
Since the FT 2210 and 2216 are used as a multi-gate type TFT and the gate length L of the TFT 2216 is large, a constant drain current can flow even if the source-drain voltage of the TFT 2210 and 2216 slightly changes. .

Regarding the location of the TFT 2209, in addition to that shown in FIG. 22A, examples shown in FIGS. 23A and 23B can be given. Further, the TFT 2209 can also be used as an erasing TFT when performing display by a time gray scale method using a digital video signal.

[Embodiment 7] In the case of the pixels shown in FIG. 1, FIG. 18, FIG. As a result, the EL element emits light in a period other than the period in which it should emit light. Although the period for emitting light is very short, it does not significantly affect the image quality. However, during charging of the capacitor means, the EL element itself becomes a load, which requires time for charging. In the present embodiment, a configuration will be described in which a current does not flow in the EL element when the electric charge is charged in the capacitance means.

FIG. 21A shows a pixel configuration example. Figure 1
A TFT 2118 is added to the pixel shown in (A). The gate electrode of the TFT 2118 is connected to the fifth gate signal line 2106, and the first electrode is the TFT 2109.
Connected to the first electrode of the TFT 2109 or the second electrode of the TFT 2109, the second electrode is connected to the power supply line, and has a potential difference with the current supply line 2114. In addition, FIG.
As indicated by the dotted line in FIG.
It may be provided between the second electrode of T2107 and the current supply line 2114 and used as a capacitor for holding a video signal. In addition, the second electrode of the TFT 2118 may be connected to the first gate signal line or the like in any pixel other than the pixel concerned. In other words, in this case, the fact that a gate signal line not selected is at a certain potential is used as a power supply line instead.

In charging the electric charge to the capacitance means 2112, the second, third and fifth gate signal lines 2103 and 210 are used.
By inputting the pulse to 4, 2106, the TFT 210
8, 2109 and 2118 are turned on and behave as shown in FIG. Since the TFT 2110 is OFF, EL
No current flows through the element 2113 and no light is emitted. Also in this case, since the current path due to the newly added TFT 2118 exists, the capacitance means 2112 is charged. After that, the fifth gate signal line 2106 becomes L level and T
When the FT 2118 is turned off, as shown in FIG. 21C, the charge accumulated in the capacitor 2112 is moved, and the TFT 2 is turned off at the moment when it falls below the threshold value of the TFT 2111.
111 is turned off, and the transfer of electric charges is also completed. Therefore, the threshold value of the TFT 2111 is held in the capacitor 2112.

In this embodiment, each TFT is independently controlled by the first to fifth gate signal lines.
The configuration is not limited to this. Considering the aperture ratio of pixels, it is desirable that the number of signal lines is as small as possible.
The TFTs that operate in synchronization, for example, the TFTs 2108 and 2109 in FIG. 21A, may be controlled to have the same polarity by using one gate signal line.

The present embodiment may be used in combination with other embodiments described in other embodiments.

[Embodiment 8] In this embodiment, a substrate in which a driving circuit formed of a CMOS circuit and a pixel portion having a switching TFT and a driving TFT are formed on the same substrate is called an active matrix substrate for convenience. . Then, in this embodiment, a manufacturing process of the active matrix substrate will be described with reference to FIGS.

As the substrate 5000, a quartz substrate, a silicon substrate, a metal substrate or a stainless steel substrate having an insulating film formed on its surface is used. Alternatively, a plastic substrate having heat resistance that can withstand the processing temperature of this manufacturing process may be used. In this example, a substrate 5000 made of glass such as barium borosilicate glass or aluminoborosilicate glass was used.

Next, a base film 5001 made of an insulating film such as a silicon oxide film, a silicon nitride film or a silicon oxynitride film is formed on the substrate 5000. The base film 5001 of this embodiment is 2
Although the insulating film has a layered structure, it may have a single layer structure of the insulating film or a structure in which two or more insulating films are laminated.

In this embodiment, as the first layer of the base film 5001, a silicon nitride oxide film 5 is formed by plasma CVD using SiH ₄ , NH ₃ and N ₂ O as reaction gases.
001a is 10 to 200 nm (preferably 50 to 100 nm)
To the thickness of. In this embodiment, the silicon oxynitride film 50 is used.
01a was formed to a thickness of 50 nm. Next, the base film 500
As the second layer of No. 1, SiH is formed by using the plasma CVD method.
Silicon oxynitride film 5001b formed by using ₄ and N ₂ O as reaction gases is 50 to 200 nm (preferably 100 to 15 nm).
It is formed to a thickness of 0 nm). In this embodiment, the silicon oxynitride film 5001b is formed to a thickness of 100 nm.

Subsequently, the semiconductor layer 50 is formed on the base film 5001.
02 to 5005 is formed. Semiconductor layers 5002-500
5 is 25 to 80 nm (preferably 30 to 60 nm) by a known means (sputtering method, LPCVD method, plasma CVD method, etc.)
A semiconductor film is formed to a thickness of (nm). Next, the semiconductor film is crystallized by a known crystallization method (laser crystallization method, thermal crystallization method using RTA or furnace annealing, thermal crystallization method using a metal element that promotes crystallization, etc.). Then, the obtained crystalline semiconductor film is patterned into a desired shape to form semiconductor layers 5002 to 5005. As the semiconductor film, a compound semiconductor film having an amorphous structure such as an amorphous semiconductor film, a microcrystalline semiconductor film, a crystalline semiconductor film, or an amorphous silicon germanium film may be used.

In this example, an amorphous silicon film having a film thickness of 55 nm was formed by using the plasma CVD method. Then, a solution containing nickel is held on the amorphous silicon film, and the amorphous silicon film is dehydrogenated (at 500 ° C. for 1 hour).
Thermal crystallization (550 ° C., 4 hours) was performed to form a crystalline silicon film. After that, semiconductor layers 5002 to 5005 were formed by patterning treatment using a photolithography method.

As a laser for forming a crystalline semiconductor film by a laser crystallization method, a continuous wave or pulsed gas laser or solid laser may be used. Examples of the former gas laser include excimer laser, YAG laser, and YVO.
₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, Ti: sapphire laser, etc. can be used. As the latter solid-state laser, Cr,
A laser using a crystal of YAG, YVO ₄ , YLF, YAlO ₃ or the like doped with Nd, Er, Ho, Ce, Co, Ti or Tm can be used. The fundamental wave of the laser depends on the doping material, 1 μm
Laser light having front and rear fundamental waves can be obtained. The harmonic wave with respect to the fundamental wave can be obtained by using a non-linear optical element. In order to obtain crystals with a large grain size when crystallizing the amorphous semiconductor film, it is preferable to use a solid-state laser capable of continuous oscillation and to apply the second to fourth harmonics of the fundamental wave. . Typically, the second harmonic (532 nm) or the third harmonic (35 nm) of the Nd: YVO ₄ laser (fundamental wave 1064 nm) is used.
5 nm) is applied.

The laser light emitted from the continuous oscillation YVO ₄ laser having an output of 10 W is converted into a harmonic by a non-linear optical element. Further, there is also a method of emitting a harmonic by inserting a YVO ₄ crystal and a non-linear optical element in the resonator. Then, preferably, a rectangular or elliptical laser beam is formed on the irradiation surface by an optical system, and the object to be processed is irradiated. Energy density at this time is 0.01-100 MW
/ Cm ² (preferably 0.1 to 10 MW / cm ² ) is required. Then, the semiconductor film is moved relative to the laser beam at a speed of about 10 to 2000 cm / s for irradiation.

When the above laser is used, it is advisable that the laser beam emitted from the laser oscillator is linearly condensed by the optical system and irradiated onto the semiconductor film. The crystallization conditions are appropriately set. When an excimer laser is used, the pulse oscillation frequency is 300 Hz and the laser energy density is 100 to 700 mJ / cm ² (typically 200 to 300 mJ / cm
² ) is good. When using a YAG laser,
Pulse oscillation frequency 1 to 300Hz using the second harmonic
And the laser energy density is 300 to 1000 mJ / c
m ² (typically 350 to 500 mJ / cm ² ) is recommended. Then, a laser beam focused linearly with a width of 100 to 1000 μm (preferably a width of 400 μm) is radiated over the entire surface of the substrate, and the overlapping ratio of the linear beams at this time (overlap ratio)
May be 50 to 98%.

However, in this embodiment, since the amorphous silicon film is crystallized using the metal element that promotes crystallization, the metal element remains in the crystalline silicon film. Therefore, an amorphous silicon film having a thickness of 50 to 100 nm is formed on the crystalline silicon film, and heat treatment (RTA method, thermal annealing using a furnace annealing furnace, or the like) is performed to form the amorphous silicon film in the amorphous silicon film. The metal element is diffused, and the amorphous silicon film is removed by etching after heat treatment. As a result, the content of the metal element in the crystalline silicon film can be reduced or removed.

After forming the semiconductor layers 5002 to 5005, a slight amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.

Next, a gate insulating film 5006 covering the semiconductor layers 5002 to 5005 is formed. Gate insulating film 50
Reference numeral 06 is formed of an insulating film containing silicon with a film thickness of 40 to 150 nm by using a plasma CVD method or a sputtering method. In this embodiment, plasma CV is used as the gate insulating film 5006.
A silicon oxynitride film was formed to a thickness of 115 nm by the D method. Of course, the gate insulating film 5006 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure.

When a silicon oxide film is used as the gate insulating film 5006, TEOS (Tet
Raethyl Orthosilicate) and O ₂ are mixed, and reaction pressure is 4
0 Pa, substrate temperature 300 to 400 ° C., high frequency (13.
It may be formed by discharging at a power density of 0.5 to 0.8 W / cm ² . The silicon oxide film manufactured through the above steps can be provided with favorable characteristics as the gate insulating film 5006 by subsequent thermal annealing at 400 to 500 ° C.

Then, a film having a thickness of 2 is formed on the gate insulating film 5006.
A first conductive film 5007 having a thickness of 0 to 100 nm and a film thickness of 100 to
A second conductive film 5008 having a thickness of 400 nm is formed by stacking. In this embodiment, a first conductive film 5007 made of a TaN film having a film thickness of 30 nm and a second conductive film 5008 made of a W film having a film thickness of 370 nm are stacked.

In this embodiment, the TaN film which is the first conductive film 5007 is formed by the sputtering method, and is formed by the sputtering method in the atmosphere containing nitrogen using the Ta target.
The W film which is the second conductive film 5008 was formed by a sputtering method using a W target. Alternatively, it can be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, it is necessary to reduce the resistance in order to use it as the gate electrode, and the resistivity of the W film is 20.
It is desirable to keep it below μΩcm. Although the resistivity of the W film can be lowered by enlarging the crystal grains, when the W film contains many impurity elements such as oxygen, crystallization is hindered and the resistance is increased. Therefore, in this embodiment, high-purity W
By the sputtering method using a target of (purity 99.9999%), and by further forming a W film so as not to mix impurities from the gas phase during film formation, the resistivity of 9 to 20 μΩcm can be obtained. Could be realized.

Note that in this embodiment, the first conductive film 5007 is used.
Was used as the TaN film and the second conductive film 5008 was used as the W film, but the materials forming the first conductive film 5007 and the second conductive film 5008 are not particularly limited. The first conductive film 5007 and the second conductive film 5008 are formed of Ta, W, Ti, Mo, A.
It may be formed of an element selected from 1, Cu, Cr, and Nd, or an alloy material or a compound material containing the above element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus or an AgPdCu alloy may be used.

Next, a mask 5009 made of resist is formed by photolithography, and a first etching treatment for forming electrodes and wirings is performed. The first etching process is performed under the first and second etching conditions. (Fig. 13 (B))

In this embodiment, ICP (Inductively Coupled Plasma) etching method is used as the first etching condition, and C is used as an etching gas.
Using F ₄ , Cl ₂ and O ₂ , each gas flow rate ratio is set to 2
At 5:25:10 (sccm), 500 W RF (13.56 MHz) power was applied to the coil-shaped electrode at a pressure of 1.0 Pa to generate plasma for etching. Board side
150 W of RF (13.56 MHz) power was also applied to the (sample stage), and a substantially negative self-bias voltage was applied. Then, the W film was etched under the first etching condition to make the end portion of the first conductive layer 5007 tapered.

Next, a mask 5009 made of resist.
Was changed to the second etching condition without removing the gas, CF ₄ and Cl ₂ were used as the etching gas, the flow rate ratio of each gas was 30:30 (sccm), and the pressure was 1.0 Pa. RF (13.56 MHz) power of 500 W was applied to the electrodes to generate plasma and etching was performed for about 15 seconds. 20 W RF (13.5 mm) on the substrate side (sample stage)
(6 MHz) power was applied and a substantially negative self-bias voltage was applied. Under the second etching condition, the first conductive layer 50
07 and the second conductive layer 5008 were etched to the same degree. Note that in order to perform etching without leaving a residue on the gate insulating film 5006, the etching time may be increased at a rate of approximately 10 to 20%.

In the above-mentioned first etching process, the shape of the mask made of resist is made suitable, and the first conductive layer 5007 and the second conductive layer 5008 are formed by the effect of the bias voltage applied to the substrate side. End has a tapered shape. Thus, the first shape conductive layers 5010 to 5014 including the first conductive layer 5007 and the second conductive layer 5008 were formed by the first etching treatment.
In the gate insulating film 5006, a region which is not covered with the first shape conductive layers 5010 to 5014 is etched by about 20 to 50 nm, so that a region with a reduced thickness is formed.

Next, a mask 5009 made of resist
The second etching process is performed without removing the. (Fig. 13
(C)) In the second etching process, S is used as an etching gas.
Using F ₆ , Cl ₂ and O ₂ , each gas flow rate ratio is 2
It was set to 4:12:24 (sccm), 700 W of RF (13.56 MHz) power was applied to the coil side power at a pressure of 1.3 Pa, plasma was generated, and etching was performed for about 25 seconds. 10W RF (13.56MHz) on the substrate side (sample stage)
Power was applied and a substantially negative self-bias voltage was applied. In this way, the W film was selectively etched to form the second shape conductive layers 5015 to 5019. At this time, the first conductive layers 5015a to 5018a are hardly etched.

Then, a mask 5009 made of resist.
The first doping process is performed without removing the
Impurity element imparting N-type to 002 to 5005 at a low concentration
Added to. The first doping process is an ion doping method or
Can be performed by an ion implantation method. Ion doping conditions
1 × 10 dose¹³~ 5 x 10¹⁴atoms / cm²And then
The fast voltage is 40 to 80 keV. In this example,
The amount is 5.0 × 10¹³atoms / cm²And the acceleration voltage is 50k
I went as eV. As the impurity element imparting N-type,
An element belonging to Group 15 may be used, typically phosphorus.
(P) or arsenic (As) is used, but phosphorus is used in this embodiment.
(P) was used. In this case, the second shape conductive layer 5015
To 5019 are masks for impurity elements that impart N-type
Therefore, the first impurity region (N--region) 5 is self-aligned.
020-5023 was formed. And the first impurity region
1 x 10 for 5020 to 5023¹⁸~ 1 x 10²⁰atoms /
cm ³An impurity element imparting N-type is added in the concentration range of
It was

Then, after removing the resist mask 5009, a new resist mask 5024 is formed, and the second doping process is performed at an acceleration voltage higher than that of the first doping process. The conditions of the ion doping method are that the dose amount is 1 × 10 ^{13 to} 3 × 10 ¹⁵ atoms / cm ² and the acceleration voltage is 60 to 120 keV. In this embodiment,
The dose was 3.0 × 10 ¹⁵ atoms / cm ² and the acceleration voltage was 65 keV. In the second doping treatment, the second conductive layers 5015b to 5018b are used as masks for the impurity elements, and the first conductive layers 5015a to 5018a are used.
Doping is performed so that the impurity element is added to the semiconductor layer below the taper portion.

As a result of performing the above second doping process, 1 × 10 ^{18 to} 5 × 10 ¹⁹ atom is formed in the second impurity region (N − region, Lov region) 5026 which overlaps with the first conductive layer.
An impurity element imparting N-type was added in the concentration range of s / cm ³ . In addition, third impurity regions (N + regions) 5025, 502
8 contains N in the concentration range of 1 × 10 ^{19 to} 5 × 10 ²¹ atoms / cm ^3.
An impurity element that imparts mold is added. After performing the first and second doping treatments, the semiconductor layers 5002 to 5
In 005, a region to which no impurity element was added or a region to which a trace amount of impurity element was added was formed. In this embodiment, a channel region 502 is defined as a region to which no impurity element is added or a region to which a trace amount of impurity element is added.
Called 7,5030. The first impurity regions (N--regions) 5020 to 5020 formed by the first doping process
Although there is a region of 5023 which is covered with the resist 5024 in the second doping treatment, in the present embodiment, the first impurity region (N--region, LDD region) continues.
Call it 5029.

Although the second impurity region (N− region) 5026 and the third impurity regions (N + regions) 5025 and 5028 are formed only by the second doping process in this embodiment, the present invention is not limited to this. . It may be formed by performing the doping process a plurality of times by appropriately changing the conditions for performing the doping process.

Next, as shown in FIG. 14A, after removing the mask 5024 made of resist, a new mask 5031 made of resist is formed. After that, a third doping process is performed. By the third doping process, P
The first layer is formed on the semiconductor layer to be the active layer of the channel TFT.
Fourth impurity regions (P + regions) 5032 and 5034 and fifth impurity regions (P− regions) 5033 and 5035 to which an impurity element imparting a conductivity type opposite to that of No. 1 is added.

In the third doping process, the second conductive layers 5016b and 5018b are used as masks against the impurity element. Thus, the impurity element imparting P-type conductivity is added, and the fourth impurity region (P + region) 503 is self-aligned.
2, 5034 and fifth impurity region (P− region) 503
3, 5035 are formed.

In this embodiment, the fourth impurity region 503 is used.
2, 5034 and fifth impurity regions 5033, 5035
Is formed by an ion doping method using diborane (B ₂ H ₆ ). The condition for the ion doping method is that the dose amount is 1 × 1.
And 0 ¹⁶ atoms / cm ^2, the accelerating voltage is 80 keV.

In the third doping process, N
The semiconductor layer forming the channel type TFT is covered with a mask 5031 made of resist.

Here, the fourth impurity regions (P + regions) 5032 and 5034 are formed by the first and second doping processes.
Further, phosphorus is added to the fifth impurity regions (P − regions) 5033 and 5035 at different concentrations. However, in any of the fourth impurity regions (P + regions) 5032 and 5034 and the fifth impurity regions (P− regions) 5033 and 5035, the impurity element imparting P-type conductivity is added by the third doping treatment. Concentration is 1 × 10 ^{19 to} 5
Doping processing is performed so that the concentration becomes × 10 ²¹ atoms / cm ³ . Thus, the fourth impurity region (P + region) 5032,
5034 and fifth impurity region (P− region) 5033, 5
035 functions as a source region and a drain region of a P-channel TFT without any problem.

In this embodiment, the fourth impurity regions (P + regions) 5032, 532 and 532 are formed only by the third doping process.
034 and the fifth impurity region (P− region) 5033, 50
35 was formed, but is not limited to this. It may be formed by performing the doping process a plurality of times by appropriately changing the conditions for performing the doping process.

Next, as shown in FIG. 14B, the mask 5031 made of resist is removed to remove the first interlayer insulating film 5.
036 is formed. The first interlayer insulating film 5036 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm by a plasma CVD method or a sputtering method. In this embodiment, a film thickness of 100 is formed by the plasma CVD method.
A silicon oxynitride film having a thickness of nm was formed. Of course, the first interlayer insulating film 5036 is not limited to the silicon oxynitride film,
Another insulating film containing silicon may be used as a single layer or a laminated structure.

Next, as shown in FIG. 14C, heat treatment (heat treatment) is performed to recover the crystallinity of the semiconductor layer and activate the impurity element added to the semiconductor layer. This heat treatment is performed by a thermal annealing method using a furnace annealing furnace. As the thermal annealing method, the oxygen concentration is 400 to 70 in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less.
The activation treatment may be performed at 0 ° C., and in this embodiment, the heat treatment is performed at 410 ° C. for 1 hour. In addition to the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied.

Further, heat treatment may be performed before forming the first interlayer insulating film 5036. However, the first conductive layers 5015a to 5019a and the second conductive layer 5015b.
If the material forming the layers 5019b to 5019b is weak against heat, the first interlayer insulating film 5 is formed to protect the wiring and the like as in the present embodiment.
036 (insulating film containing silicon as a main component, eg, silicon nitride film)
It is preferable to perform heat treatment after forming the.

As described above, the first interlayer insulating film 5036
By performing heat treatment after forming (an insulating film containing silicon as a main component, for example, a silicon nitride film), at the same time as the activation treatment,
Hydrogenation of the semiconductor layer can also be performed. In the hydrogenation step, dangling bonds in the semiconductor layer are terminated by hydrogen contained in the first interlayer insulating film 5036.

Note that heat treatment for hydrogenation may be performed separately from heat treatment for activation treatment.

Here, the semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film 5036. As another means of hydrogenation, a means using hydrogen excited by plasma (plasma hydrogenation) or heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen is performed. Means may be used.

Next, on the first interlayer insulating film 5036,
A second interlayer insulating film 5037 is formed. An inorganic insulating film can be used as the second interlayer insulating film 5037. For example, a silicon nitride film or a silicon nitride oxide film formed by the CVD method, a silicon nitride film or a silicon nitride oxide film applied by the SOG (Spin On Glass) method, or the like can be used. In addition, the second interlayer insulating film 503
An organic insulating film can be used as 7. For example,
A film made of polyimide, polyamide, BCB (benzocyclobutene), acrylic, or the like can be used. Alternatively, a stacked structure of an acrylic film and a silicon nitride film or a silicon nitride oxide film may be used.

In this example, an acrylic film having a thickness of 1.6 μm was formed. The second interlayer insulating film 5037 can reduce unevenness due to the TFT formed over the substrate 5000 and flatten it. In particular, the second interlayer insulating film 503
Since 7 has a strong implication of flattening, a film having excellent flatness is preferable.

Next, dry etching or wet etching is used to etch the second interlayer insulating film 5037, the first interlayer insulating film 5036, and the gate insulating film 5006, and the third impurity regions 5025, 5028 and the fourth impurity regions 5025, 5028. Contact holes reaching the impurity regions 5032 and 5034 are formed.

Next, the pixel electrode 50 made of a transparent conductive film.
38 is formed. As the transparent conductive film, a compound of indium oxide and tin oxide (Indium Tin Oxide: ITO), a compound of indium oxide and zinc oxide, zinc oxide, tin oxide,
Indium oxide or the like can be used. Moreover, you may use what added the gallium to the said transparent conductive film. The pixel electrode corresponds to the anode of the EL element.

In this embodiment, ITO is formed into a film having a thickness of 110 nm and then patterned to form a pixel electrode 5038.

Then, wirings 5039 to 5045 electrically connected to the respective impurity regions are formed. Note that in this embodiment, the wirings 5039 to 5045 have a film thickness of 100 nm.
The Ti film, the Al film having a film thickness of 350 nm, and the Ti film having a film thickness of 100 nm are continuously formed by a sputtering method and patterned into a desired shape.

Of course, the structure is not limited to the three-layer structure, and may be a single-layer structure, a two-layer structure, or a laminated structure of four or more layers. The material of the wiring is not limited to Al and Ti, but other conductive films may be used. For example, wiring may be formed by forming Al or Cu on the TaN film and then patterning the laminated film on which the Ti film is formed.

Thus, one of the source region and the drain region of the N-channel TFT in the pixel portion is provided with the wiring 5042.
Source signal line (stack of 5019a and 5019b)
The other side is electrically connected to the gate electrode of the P-channel TFT in the pixel portion by the wiring 5043. Further, one of a source region and a drain region of the P-channel TFT in the pixel portion is electrically connected to the pixel electrode 5047 by a wiring 5044. Here, the wiring 5044 and the pixel electrode 5047 are electrically connected to each other by forming a part of the wiring 5044 over the pixel electrode 5047.

Through the above steps, as shown in FIG. 14D, a driving circuit portion having a CMOS circuit composed of N-channel TFTs and P-channel TFTs, and a switching T
A pixel portion having an FT and a driving TFT can be formed over the same substrate.

The N-channel TFT in the driver circuit portion has a low-concentration impurity region 5026 (Lov region) overlapping with the first conductive layer 5015a forming part of the gate electrode and a high-concentration impurity region functioning as a source or drain region. Area 50
25 and. A P-channel TFT which is connected to the N-channel TFT 501 by a wiring 5040 to form a CMOS circuit has a low-concentration impurity region 5033 (Lo) which overlaps with a first conductive layer 5016a which forms part of a gate electrode.
v region), and a high-concentration impurity region 5032 which functions as a source region or a drain region.

In the pixel portion, the N-channel switching TFT has a low-concentration impurity region 5029 (Loff region) formed outside the gate electrode and a high-concentration impurity region 5028 functioning as a source region or a drain region. is doing. In the pixel portion, the P-channel driving TFT has a low-concentration impurity region 5035 (Lov that overlaps with the first conductive layer 5018a which forms part of the gate electrode).
Region), and a high concentration impurity region 5034 which functions as a source region or a drain region.

Next, a third interlayer insulating film 5046 is formed. An inorganic insulating film or an organic insulating film can be used as the third interlayer insulating film. As an inorganic insulating film, CV
A silicon nitride film or a silicon nitride oxide film formed by the D method, a silicon nitride film or a silicon nitride oxide film applied by the SOG (Spin On Glass) method, or the like can be used. An acrylic resin film or the like can be used as the organic insulating film.

An example of a combination of the second interlayer insulating film 5037 and the third interlayer insulating film 5046 is given below.

A silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method is used as the second interlayer insulating film 5037, and a silicon nitride film or a nitride oxide film formed by a plasma CVD method is also used as the third interlayer insulating film 5046. There is a combination using a silicon film. A silicon nitride film or a silicon nitride oxide film formed by an SOG method is used as the second interlayer insulating film 5037, and a silicon nitride film or a silicon nitride oxide film formed by the SOG method is also used as the third interlayer insulating film 5046. There are combinations to use. As the second interlayer insulating film 5037, a stacked film of a silicon nitride film or a silicon nitride oxide film formed by an SOG method and a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method is used. Membrane 50
As 46, there is a combination of using a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method.
There is a combination in which acrylic is used as the second interlayer insulating film 5037 and acrylic is also used as the third interlayer insulating film 5046. In addition, the second interlayer insulating film 5037
A combination of using a stacked film of acrylic and a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method and using a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method as the third interlayer insulating film 5046 is there. As the second interlayer insulating film 5037, a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method is used, and the third interlayer insulating film 504 is used.
There is a combination in which acrylic is used as 6.

Pixel electrode 50 of third interlayer insulating film 5046
An opening is formed at a position corresponding to 47. The third interlayer insulating film functions as a bank. When forming the opening,
By using a wet etching method, it is possible to easily form a tapered side wall. If the side wall of the opening is not sufficiently gentle, the deterioration of the EL layer due to the step difference becomes a significant problem, so caution is required.

Carbon particles or metal particles may be added to the third interlayer insulating film to lower the resistivity and suppress the generation of static electricity. At this time, the resistivity is 1 × 10 ⁶ to 1 × 10 ¹²
The addition amount of carbon particles or metal particles may be adjusted so that it becomes Ωm (preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ωm).

Next, an EL layer 5047 is formed on the pixel electrode 5038 exposed in the opening of the third interlayer insulating film 5046.

As the EL layer 5047, a known organic light emitting material or inorganic light emitting material can be used.

As the organic light emitting material, a low molecular weight organic light emitting material, a high molecular weight organic light emitting material and a medium molecular weight organic light emitting material can be freely used. Here, the medium-molecular organic light-emitting material means an organic light-emitting material which has no sublimability and has a number of molecules of 20 or less or a length of chained molecules of 10 μm or less.

The EL layer 5047 usually has a laminated structure.
Typically, Kodak Eastman Company Ta
The laminated structure of “hole transport layer / light emitting layer / electron transport layer” proposed by ng et al. In addition, a hole injection layer / hole transport layer / light emitting layer / electron transport layer or a hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer are laminated in this order on the anode. The structure is fine. You may dope a fluorescent dye etc. with respect to a light emitting layer.

In this embodiment, the EL layer 5047 is formed using a low molecular weight organic light emitting material by an evaporation method. Specifically, a 20 nm thick copper phthalocyanine is used as the hole injection layer.
A (CuPc) film is provided, and a 70 nm-thick tris-8-quinolinolato aluminum complex (Alq ₃ ) is formed thereon as a light emitting layer.
It has a laminated structure provided with a film. The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene or DCM1 to Alq ₃ .

Although only one pixel is shown in FIG. 14D, a plurality of colors such as R (red), G (green), and B (blue) are used.
The EL layer 5047 corresponding to each color can be separately formed.

As an example of using a high molecular organic light emitting material, a 20 nm polythiophene (PE
DOT) film is formed by spin coating method, and para-phenylene vinylene (PPV) having a thickness of about 100 nm is formed as a light emitting layer on the film.
The EL layer 5047 may be formed using a stacked structure including a film. By using a PPV π-conjugated polymer, the emission wavelength can be selected from red to blue. It is also possible to use an inorganic material such as silicon carbide for the electron transport layer and the electron injection layer.

[0209] Note that the EL layer 5047 is not limited to a layer in which a hole injecting layer, a hole transporting layer, a light-emitting layer, an electron transporting layer, an electron injecting layer, or the like has a clearly distinguished layered structure. That is, the EL layer 5047 may have a structure including a layer in which materials forming the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, the electron injecting layer, and the like are mixed.

For example, a mixed layer composed of a material forming an electron transport layer (hereinafter referred to as an electron transport material) and a material forming a light emitting layer (hereinafter referred to as a light emitting material) is used as an electron transport layer. EL having a structure between a light emitting layer and a light emitting layer
It may be layer 5047.

Next, a pixel electrode 5048 made of a conductive film is provided on the EL layer 5047. In the case of this embodiment,
An alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (alloy film of magnesium and silver) may be used. The pixel electrode 5048 corresponds to the cathode of the EL element. As the cathode material, a conductive film made of an element belonging to Group 1 or 2 of the periodic table or a conductive film to which those elements are added can be freely used.

When the pixel electrode 5048 is formed, E
The L element is completed. Note that an EL element means a pixel electrode (anode) 5038, an EL layer 5047, and a pixel electrode (cathode) 50.
The element formed by 48.

It is effective to provide the passivation film 5049 so as to completely cover the EL element. The passivation film 5049 is formed of an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film, and the insulating film can be used as a single layer or a stacked layer in which they are combined.

It is preferable to use a film having good coverage as the passivation film 5049, and a carbon film, especially D
It is effective to use an LC (diamond-like carbon) film. Since the DLC film can be formed in a temperature range of room temperature to 100 ° C. or lower, it can be easily formed over the EL layer 5047 having low heat resistance. In addition, the DLC film has a high oxygen blocking effect, and thus the EL layer 504 has
It is possible to suppress the oxidation of 7. Therefore, EL
The problem that the layer 5047 is oxidized can be prevented.

Note that the steps from the formation of the third interlayer insulating film 5046 to the formation of the passivation film 5049 are continuously performed using a multi-chamber system (or in-line system) film formation apparatus without exposing to the atmosphere. It is effective to process it.

[0216] Actually, when the state shown in Fig. 14 (D) is completed, a protective film (laminate film, ultraviolet curing resin film, etc.) having high airtightness and little degassing and a transparent film are provided so as not to be further exposed to the outside air. It is preferable to perform packaging (encapsulation) with an optical sealing material. At that time, the reliability of the EL element is improved by making the inside of the sealing material an inert atmosphere or disposing a hygroscopic material (for example, barium oxide) inside.

When the airtightness is improved by a process such as packaging, a connector (flexible printed circuit: FP) for connecting a terminal routed from an element or a circuit formed on the substrate 5000 and an external signal terminal.
C) is attached to complete the product.

According to the steps shown in this embodiment, the number of photomasks required for manufacturing a light emitting device can be suppressed. As a result, the process can be shortened, the manufacturing cost can be reduced, and the yield can be improved.

[Embodiment 9] In this embodiment, a manufacturing process of an active matrix substrate having a structure different from that shown in Embodiment 8 will be described with reference to FIGS.

Note that the steps up to FIG.
1 is the same as the process shown in FIGS. 13 (A) to 13 (D) and FIG. 14 (A). However, the driving TF that constitutes the pixel portion
T is a low-concentration impurity region formed outside the gate electrode
The difference is that it is an N-channel type TFT having (Loff region). In this driving TFT, as shown in the ninth embodiment, a low-concentration impurity region (Loff region) may be formed outside the gate electrode by using a resist mask.

The same parts as those in FIGS. 13 and 14 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 15A, a first interlayer insulating film 5101 is formed. This first interlayer insulating film 5101
As a plasma CVD method or a sputtering method,
It is formed of an insulating film containing silicon with a thickness of 100 to 200 nm. In this embodiment, the film thickness is 10 by the plasma CVD method.
A 0 nm silicon oxynitride film was formed. Of course, the first interlayer insulating film 5101 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure.

Next, as shown in FIG. 15B, heat treatment (heat treatment) is performed to recover the crystallinity of the semiconductor layer and activate the impurity element added to the semiconductor layer. This heat treatment is performed by a thermal annealing method using a furnace annealing furnace. As the thermal annealing method, the oxygen concentration is 400 to 70 in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less.
The activation treatment may be performed at 0 ° C., and in this embodiment, the heat treatment is performed at 410 ° C. for 1 hour. In addition to the thermal annealing method, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied.

Heat treatment may be performed before forming the first interlayer insulating film 5101. However, the first conductive layers 5015a to 5019a and the second conductive layer 5015b.
If 5050b is weak to heat, heat treatment is performed after forming the first interlayer insulating film 5101 (insulating film containing silicon as a main component, for example, a silicon nitride film) for protecting wirings and the like as in this embodiment. Is preferably performed.

As described above, the first interlayer insulating film 5101
By performing heat treatment after forming (an insulating film containing silicon as a main component, for example, a silicon nitride film), at the same time as the activation treatment,
Hydrogenation of the semiconductor layer can also be performed. In the hydrogenation step, dangling bonds in the semiconductor layer are terminated by hydrogen contained in the first interlayer insulating film 5101.

[0226] Note that heat treatment for hydrogenation may be performed separately from heat treatment for activation treatment.

Here, the semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film 5101. As another means of hydrogenation, a means using hydrogen excited by plasma (plasma hydrogenation) or heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen is performed. Means may be used.

Through the above steps, a pixel portion including a driver circuit portion including a CMOS circuit including an N-channel TFT and a P-channel TFT, a switching TFT, and a driver TFT can be formed over the same substrate. .

Next, on the first interlayer insulating film 5101,
A second interlayer insulating film 5102 is formed. An inorganic insulating film can be used as the second interlayer insulating film 5102. For example, a silicon nitride film or a silicon nitride oxide film formed by the CVD method, a silicon nitride film or a silicon nitride oxide film applied by the SOG (Spin On Glass) method, or the like can be used. In addition, the second interlayer insulating film 510
For 2, an organic insulating film can be used. For example,
A film made of polyimide, polyamide, BCB (benzocyclobutene), acrylic, or the like can be used. Alternatively, a stacked structure of an acrylic film and a silicon nitride film or a silicon nitride oxide film may be used.

Next, the first interlayer insulating film 5101, the second interlayer insulating film 5102, and the gate insulating film 5006 are etched by dry etching or wet etching, and the impurities of each TFT forming the driver circuit portion and the pixel portion are etched. Contact holes reaching the regions (third impurity region (N + region) and fourth impurity region (P + region)) are formed.

Then, wirings 5103 to 5109 electrically connected to the respective impurity regions are formed. Note that in this embodiment, the wirings 5103 to 5109 have a film thickness of 100 nm.
The Ti film, the Al film having a film thickness of 350 nm, and the Ti film having a film thickness of 100 nm are continuously formed by a sputtering method and patterned into a desired shape.

Of course, the structure is not limited to the three-layer structure, and may be a single-layer structure, a two-layer structure, or a laminated structure of four or more layers. The material of the wiring is not limited to Al and Ti, but other conductive films may be used. For example, wiring may be formed by forming Al or Cu on the TaN film and then patterning the laminated film on which the Ti film is formed.

[0233] One of a source region and a drain region of the switching TFT in the pixel portion is electrically connected to a source wiring (a stack of 5019a and 5019b) by a wiring 5106, and the other is connected by a wiring 5107 for driving the pixel portion. It is electrically connected to the gate electrode of the TFT.

Next, as shown in FIG. 15C, a third interlayer insulating film 5110 is formed. Third interlayer insulating film 511
As 0, an inorganic insulating film or an organic insulating film can be used. As the inorganic insulating film, a silicon nitride film or a silicon nitride oxide film formed by a CVD method, an SOG (Spin
A silicon nitride film or a silicon oxynitride film applied by the On Glass method can be used. An acrylic resin film or the like can be used as the organic insulating film.

The third interlayer insulating film 5110 can alleviate the unevenness due to the TFT formed on the substrate 5000 and flatten it. In particular, the third interlayer insulating film 511
Since 0 has a strong meaning of flattening, a film having excellent flatness is preferable.

Then, dry etching or wet etching is used to form a contact hole reaching the wiring 5108 in the third interlayer insulating film 5110.

Next, the conductive film is patterned to form a pixel electrode 5111. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (alloy film of magnesium and silver) may be used. The pixel electrode 5111 corresponds to the cathode of the EL element. As the cathode material, a conductive film made of an element belonging to Group 1 or 2 of the periodic table or a conductive film to which those elements are added can be freely used.

The pixel electrode 5111 is the third interlayer insulating film 5
The wiring 5 is formed by the contact hole formed in 110.
An electrical connection is made with 108. In this way, the pixel electrode 5111 is electrically connected to one of the source region and the drain region of the driving TFT.

Next, as shown in FIG. 15D, a bank 5112 is formed in order to separately paint the EL layer between each pixel. The bank 5112 is formed using an inorganic insulating film or an organic insulating film. As the inorganic insulating film, a silicon nitride film or a silicon oxynitride film formed by a CVD method, S
A silicon nitride film or a silicon nitride oxide film applied by the OG method can be used. An acrylic resin film or the like can be used as the organic insulating film.

Here, when the bank 5112 is formed, it is possible to easily form a tapered side wall by using a wet etching method. If the side wall of the bank 5112 is not sufficiently gentle, the deterioration of the EL layer due to the step difference becomes a significant problem, so caution is required.

Note that when electrically connecting the pixel electrode 5111 and the wiring 5108, a bank 5112 is also formed in the contact hole portion formed in the third interlayer insulating film 5110. Thus, the unevenness of the pixel electrode due to the unevenness of the contact hole portion is filled with the bank 5112, so that the deterioration of the EL layer due to the step is prevented.

Third interlayer insulating film 5110 and bank 5112
An example of the combination of is given below.

A silicon nitride film or a silicon oxynitride film formed by a plasma CVD method is used as the third interlayer insulating film 5110, and the bank 5112 is also plasma CVD.
There is a combination of using a silicon nitride film or a silicon nitride oxide film formed by the method. In addition, the third interlayer insulating film 5
A silicon nitride film or a silicon nitride oxide film formed by the SOG method is used as 110, and the bank 5112 is made of S.
There is a combination of using a silicon nitride film or a silicon nitride oxide film formed by the OG method. A stacked film of a silicon nitride film or a silicon nitride oxide film formed by an SOG method and a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method is used as the third interlayer insulating film 5110, and a plasma CVD method is used as a bank 5112. There is a combination using a silicon nitride film or a silicon nitride oxide film formed by. Further, as the third interlayer insulating film 5110,
There is a combination of using acrylic and also using acrylic as the bank 5112. In addition, the third interlayer insulating film 5110
As a combination, there is a combination of using a stacked film of acrylic and a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method, and using a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method as the bank 5112. Further, there is a combination in which a silicon nitride film or a silicon nitride oxide film formed by a plasma CVD method is used as the third interlayer insulating film 5110 and acrylic is used as the bank 5112.

Carbon particles or metal particles may be added to the bank 5112 to lower the resistivity and suppress the generation of static electricity. At this time, the resistivity is 1 × 10 ⁶ to 1 × 10 ¹² Ωm
The addition amount of carbon particles or metal particles may be adjusted so that it is (preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ωm).

Next, an EL layer 5113 is formed on the exposed pixel electrode 5111 surrounded by the bank 5112.

As the EL layer 5113, a known organic light emitting material or inorganic light emitting material can be used.

As the organic light emitting material, a low molecular weight organic light emitting material, a high molecular weight organic light emitting material, or a medium molecular weight organic light emitting material can be freely used. Here, the medium-molecular organic light-emitting material means an organic light-emitting material which has no sublimability and has a number of molecules of 20 or less or a length of chained molecules of 10 μm or less.

The EL layer 5113 usually has a laminated structure.
Typically, Kodak Eastman Company Ta
The laminated structure of “hole transport layer / light emitting layer / electron transport layer” proposed by ng et al. In addition, an electron transport layer / a light emitting layer / a hole transport layer / a hole injection layer, or an electron injection layer / an electron transport layer / a light emitting layer / a hole transport layer / a hole injection layer are laminated in this order on the cathode. The structure is fine. You may dope a fluorescent dye etc. with respect to a light emitting layer.

In this embodiment, the EL layer 5113 is formed by a vapor deposition method using a low molecular weight organic light emitting material. Specifically, a 70 nm thick tris-8-quinolinolato aluminum complex (Alq ₃ ) film is provided as a light emitting layer, and a 20 nm thick copper phthalocyanine (CuPc) film is provided thereon as a hole injection layer.
It has a laminated structure provided with a film. The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene or DCM1 to Alq ₃ .

Although only one pixel is shown in FIG. 15D, a plurality of colors such as R (red), G (green) and B (blue) are used.
The EL layer 5113 corresponding to each color can be separately formed.

As an example of using a high molecular weight organic light emitting material, a 20 nm polythiophene (PE
A DOT film is formed by a spin coating method, and para-phenylene vinylene (PP) having a thickness of about 100 nm is formed thereon as a light emitting layer.
V) The EL layer 5113 may have a stacked structure including a film. By using a PPV π-conjugated polymer, the emission wavelength can be selected from red to blue. It is also possible to use an inorganic material such as silicon carbide for the electron transport layer and the electron injection layer.

[0252] Note that the EL layer 5113 is not limited to a layer in which a hole-injection layer, a hole-transport layer, a light-emitting layer, an electron-transport layer, an electron-injection layer, and the like have a clearly distinguished layered structure. That is, the EL layer 5113 may have a structure including a layer in which materials forming the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, the electron injecting layer, and the like are mixed.

For example, a mixed layer composed of a material forming the electron transport layer (hereinafter referred to as an electron transport material) and a material forming the light emitting layer (hereinafter referred to as a light emitting material) is used as an electron transport layer. EL having a structure between a light emitting layer and a light emitting layer
It may be layer 5113.

Next, a pixel electrode 5114 made of a transparent conductive film is formed on the EL layer 5113. As the transparent conductive film, a compound of indium oxide and tin oxide (ITO),
A compound of indium oxide and zinc oxide, zinc oxide, tin oxide, indium oxide, or the like can be used. Moreover, you may use what added the gallium to the said transparent conductive film. The pixel electrode 5114 corresponds to the anode of the EL element.

[0255] E when the pixel electrode 5114 is formed
The L element is completed. Note that an EL element means a pixel electrode (cathode) 5111, an EL layer 5113, and a pixel electrode (anode) 51.
14 indicates a diode formed.

In this embodiment, since the pixel electrode 5114 is formed of the transparent conductive film, the light emitted by the EL element is emitted toward the side opposite to the substrate 5000. In addition, the wiring 5106 is formed by the third interlayer insulating film 5110.
5109 is formed on a layer different from the layer on which the pixel electrode 51 is formed.
11 is formed. Therefore, the aperture ratio can be increased as compared with the configuration shown in the ninth embodiment.

Protective film covering EL element completely
It is effective to provide (passivation film) 5115. The protective film 5115 is formed of an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film, and the insulating film can be used as a single layer or a stacked layer in which they are combined.

When the light emitted from the EL element is emitted from the pixel electrode 5114 side as in this embodiment, the protective film 5 is used.
It is necessary to use a film that transmits light as 115.

The steps from the formation of the bank 5112 to the formation of the protective film 5115 are the multi-chamber method.
It is effective to use a (or in-line) film forming apparatus to perform continuous processing without exposing to the atmosphere.

[0260] Actually, when the state shown in Fig. 15 (D) is completed, a protective film (laminate film, ultraviolet curable resin film, etc.) having high airtightness and little degassing is provided so as not to be further exposed to the outside air. It is preferable to package (enclose) with a sealing material. At that time, the reliability of the EL element is improved by making the inside of the sealing material an inert atmosphere or disposing a hygroscopic material (for example, barium oxide) inside.

When the airtightness is improved by a process such as packaging, a connector (flexible printed circuit: FP) for connecting a terminal routed from an element or a circuit formed on the substrate 5000 and an external signal terminal.
C) is attached to complete the product.

[Embodiment 10] In this embodiment, an example in which a light emitting device is manufactured by using the present invention will be described with reference to FIGS.

FIG. 16 is a top view of a light emitting device formed by sealing an element substrate on which a TFT is formed with a sealing material, and FIG. 16B is an AA line of FIG. 16A. 16A is a cross-sectional view of FIG. 16C, and FIG.
It is sectional drawing in -B '.

[0264] The pixel portion 400 provided over the substrate 4001
2, source signal line driver circuit 4003, first and second
A sealant 4009 is provided so as to surround the gate signal line driver circuits 4004a and 4004b. In addition, the pixel portion 4002 and the source signal line driver circuit 4003
And the first and second gate signal line driver circuits 4004a,
A sealing material 4008 is provided on the surface 4004b. Therefore, the pixel portion 4002, the source signal line driver circuit 4003, and the first and second gate signal line driver circuits 40
04a and 4004b are the substrate 4001 and the sealing material 40.
09 and the sealing material 4008, the filler 421
It is sealed at 0.

Further, the pixel portion 4 provided on the substrate 4001
002, the source signal line driver circuit 4003, and the first and second gate signal line driver circuits 4004a and 4004b each include a plurality of TFTs. In FIG. 16B, the TFTs included in the source signal line driver circuit 4003 which are typically formed over the base film 4010 (here, an N-channel TFT and a P-channel TFT are shown) 420
1 and the TFT 4202 included in the pixel portion 4002 is illustrated.

An interlayer insulating film (planarizing film) 4301 is formed on the TFTs 4201 and 4202, and the TFT 4 is formed thereon.
Pixel electrode (anode) 4 electrically connected to the drain of 202
203 is formed. A transparent conductive film having a high work function is used as the pixel electrode 4203. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide or indium oxide can be used. Moreover, you may use what added gallium to the said transparent conductive film.

An insulating film 4302 is formed on the pixel electrode 4203, and the insulating film 4302 forms the pixel electrode 420.
3, an opening is formed on the upper part. In this opening, the organic light emitting layer 4204 is formed on the pixel electrode 4203. As the organic light emitting layer 4204, a known organic light emitting material or inorganic light emitting material can be used. Further, the organic light emitting material includes a low molecular weight (monomer type) material and a high molecular weight (polymer type) material, and either one may be used.

As a method of forming the organic light emitting layer 4204, a known vapor deposition technique or coating technique may be used. Further, the structure of the organic light emitting layer may be a laminated structure or a single layer structure by freely combining the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer or the electron injection layer.

A cathode 4205 made of a conductive film having a light-shielding property (typically, a conductive film containing aluminum, copper or silver as a main component or a laminated film of these and another conductive film) is formed on the organic light emitting layer 4204. Is formed. Also, the cathode 4
It is desirable to exclude water and oxygen existing at the interface between 205 and the organic light emitting layer 4204 as much as possible. Therefore, it is necessary to devise the organic light emitting layer 4204 in a nitrogen or rare gas atmosphere and to form the cathode 4205 without exposing it to oxygen or moisture. In this embodiment, the above-described film formation is possible by using a multi-chamber type (cluster tool type) film forming apparatus. A predetermined voltage is applied to the cathode 4205.

As described above, the pixel electrode (anode) 420
3, the light emitting element 4303 including the organic light emitting layer 4204 and the cathode 4205 is formed. Then, a protective film 4303 is formed over the insulating film 4302 so as to cover the light emitting element 4303. The protective film 4303 is effective in preventing oxygen, moisture, and the like from entering the light-emitting element 4303.

Reference numeral 4005a is a lead wiring connected to the power supply line, and is connected to the first electrode of the TFT 4202. The lead wiring 4005a passes between the sealing material 4009 and the substrate 4001 and is connected to the anisotropic conductive film 4300.
FPC wiring 4301 included in the FPC 4006 via the
Electrically connected to.

As the sealing material 4008, a glass material, a metal material (typically a stainless material), a ceramic material, and a plastic material (including a plastic film) can be used. As a plastic material, FRP (F
An iberglass-Reinforced-Plastics) plate, a PVF (polyvinyl fluoride) film, a mylar film, a polyester film or an acrylic resin film can be used. Alternatively, a sheet having a structure in which an aluminum foil is sandwiched between PVF films or mylar films can be used.

However, when the light emission direction from the light emitting element is toward the cover material side, the cover material must be transparent. In that case, a transparent material such as a glass plate, a plastic plate, a polyester film or an acrylic film is used.

As the filler 4103, an ultraviolet curable resin or a thermosetting resin can be used in addition to an inert gas such as nitrogen or argon, and PVC (polyvinyl chloride), acrylic, polyimide, epoxy resin, silicone can be used. Resin, PVB (polyvinyl butyral) or EVA
(Ethylene vinyl acetate) can be used. In this example, nitrogen was used as the filler.

In order to expose the filler 4103 to a hygroscopic substance (preferably barium oxide) or a substance capable of adsorbing oxygen, the substrate 400 of the sealing material 4008 is used.
A concave portion 4007 is provided on the surface on the first side, and a hygroscopic substance or a substance 4207 capable of adsorbing oxygen is arranged. The hygroscopic substance or the substance 4207 capable of adsorbing oxygen is held by the recessed cover material 4208 in the recess 4007 so that the hygroscopic substance or the substance 4207 capable of adsorbing oxygen does not scatter. Note that the recess cover material 4208 has a fine mesh shape and has a structure in which air and moisture can pass through and a hygroscopic substance or a substance that can adsorb oxygen 4207 cannot pass through. By providing the hygroscopic substance or the substance 4207 capable of adsorbing oxygen, deterioration of the light-emitting element 4303 can be suppressed.

As shown in FIG. 16C, the pixel electrode 420
Simultaneously with the formation of No. 3, a conductive film 4203a is formed so as to be in contact with the lead wiring 4005a.

The anisotropic conductive film 4300 has a conductive filler 4300a. Substrate 4001 and F
By thermocompression bonding with PC 4006, the conductive film 4203a on the substrate 4001 and the FPC wiring 4301 on the FPC 4006 are electrically connected by the conductive filler 4300a.

[Embodiment 11] In the present invention, by using an organic light-emitting material capable of utilizing phosphorescence from triplet excitons for light emission, external emission quantum efficiency can be dramatically improved. As a result, it is possible to reduce the power consumption of the light emitting element, extend the life of the light emitting element, and reduce the weight thereof.

Here, a report will be presented in which triplet excitons are used to improve the external emission quantum efficiency. (T.Tsutsui, C.Adachi, S.Saito, Photochemical Proce
sses in Organized Molecular Systems, ed.K.Honda,
(Elsevier Sci.Pub., Tokyo, 1991) p.437.)

Organic light-emitting materials reported by the above papers
The molecular formula of (coumarin dye) is shown below.

[0281]

[Chemical 1]

(MA Baldo, DFO'Brien, Y.You, A.Sho
ustikov, S. Sibley, METhompson, SRForrest, Natur
e 395 (1998) p.151.)

Organic light-emitting materials reported by the above papers
The molecular formula of (Pt complex) is shown below.

[0284]

[Chemical 2]

(MA Baldo, S. Lamansky, PEBurrrows,
METhompson, SRForrest, Appl.Phys.Lett., 75 (199
9) p.4.) (T.Tsutsui, M.-J.Yang, M.Yahiro, K.Nakamu
ra, T.Watanabe, T.tsuji, Y.Fukuda, T.Wakimoto, S.Ma
yaguchi, Jpn.Appl.Phys., 38 (12B) (1999) L1502.)

Organic light-emitting materials reported by the above papers
The molecular formula of (Ir complex) is shown below.

[0287]

[Chemical 3]

As described above, if phosphorescence emission from triplet excitons can be utilized, it is possible in principle to realize external emission quantum efficiency that is 3 to 4 times higher than that when fluorescence emission from singlet excitons is used. .

[Embodiment 12] As a method of correcting the threshold value of a transistor according to the present invention, a current is passed between the source and the drain in a state where the gate and the drain of the transistor used for the correction are short-circuited to form a diode The phenomenon in which the voltage between the drains becomes equal to the threshold value of the transistor is used, but this can be applied not only to the pixel portion introduced in the present invention but also to a driving circuit.

As an example, a current source circuit in a drive circuit that outputs a current to a pixel is given. The current source circuit is a circuit that outputs a desired current from the input voltage signal. A voltage signal is input to the gate electrode of the current source transistor in the current source circuit, and a current corresponding to the gate-source voltage is output via the current source transistor. That is, the threshold correction method of the present invention is used for the threshold correction of the current source transistor.

FIG. 27A shows an example of using the current source circuit. Sampling pulses are sequentially output from the shift register, and the sampling pulses are supplied to the respective current source circuits 9
The sampling signal is input to 001 and the sampling pulse is sampled according to the timing when the sampling pulse is input to the current source circuit 9001. In this case, the sampling operation is performed dot-sequentially.

A simple operation timing is shown in FIG. The period in which the gate signal line of the i-th row is selected is divided into a period in which sampling pulses are output from the shift register and sampling of the video signal and a blanking period. In this blanking period, the threshold value correcting operation of the present invention, that is, the series of operations of initializing the potential of each part and acquiring the threshold voltage of the transistor is performed. That is, the threshold acquisition operation can be performed every horizontal period.

FIG. 28A shows a structure of a driver circuit which outputs a current having a structure different from that of FIG. 27 to a pixel or the like. Figure 2
The difference from the case of No. 7 is that the current source circuit 9001 controlled by one-stage sampling pulse is
There are two, A and 9001B, and both operations are selected by the current source control signal.

As shown in FIG. 28B, the current source control signal is switched, for example, every horizontal period.
Then, in the operation of the current source circuits 9001A and 9001B, one outputs a current to a pixel or the like and the other inputs a video signal. This is done line by line. In this case, the sampling operation is performed line-sequentially.

FIG. 29A shows the structure of a drive circuit having a further different structure. Here, the current source circuit 9001 controlled by one-stage sampling pulse is
A, 9001B, and 9001C, and each operation is selected by a video input control signal and an output control signal.

As shown in FIG. 29B, the operation of the current source circuits 9001A to 9001C is changed from the threshold value correction to the video signal input to the pixel every horizontal period by the video input control signal and the output control signal. The current output is changed in order. The sampling operation is performed line-sequentially as in the configuration shown in FIG.

FIG. 30A shows the structure of a drive circuit having a different structure. In the configuration of FIG. 27, the format of the video signal may be digital or analog, but FIG.
In the configuration of (A), a digital video signal is input. The input digital video signal is taken into the first latch circuit according to the output of the sampling pulse, and after the video signal for one row is taken in, it is transferred to the second latch circuit, and then each current source circuit. It is input to 9001A to 9001C. Here, the current source circuits 9001A to 9001
1C has different current values output from them. For example, the current value ratio is 1: 2: 4. That is, n current source circuits are arranged in parallel, the ratio of the current values is set to 1: 2: 4: ... 2 ^(n-1) , and the currents output from the current source circuits are added together. Thus, the output current value can be changed linearly.

The operation timing is almost the same as that shown in FIG. 27, and the threshold correction operation is performed in the current source circuit 9001 within the blanking period in which the sampling operation is not performed, and then the latch circuit is operated. The held data is transferred, V-I conversion is performed in the current source circuit 9001, and a current is output to the pixel. The sampling operation is shown in Figure 2.
Similar to the configuration shown in FIG. 8, the line sequential operation is performed.

FIG. 31A shows a structure of a driver circuit which outputs a current having a different structure to a pixel or the like. With this configuration, the digital video signal captured by the latch circuit is
When the latch signal is input, it is transferred to the D / A conversion circuit and converted into an analog video signal. The analog video signal is input to each current source circuit 9001 and a current is output.

Further, such a D / A conversion circuit may be provided with a function for gamma correction, for example.

As shown in FIG. 31B, during the blanking period, the threshold value correction and the latch data transfer are performed, and the sampling operation of a certain row is performed. I conversion and current output to pixels are performed. The sampling operation is performed line-sequentially as in the configuration shown in FIG.

The threshold value correcting means of the present invention can be applied to the case where the V-I conversion is performed by the current source circuit, not limited to the above-mentioned configuration. Also, FIG. 28 and FIG.
As shown in FIG. 9, a plurality of current source circuits are arranged in parallel,
The configuration of switching and using may be used in combination with the configuration of FIG. 30, FIG.

[Embodiment 13] In the structure shown so far in the present specification, a P-channel type TFT is used as the driving TFT, but in the present invention, the N-channel type TFT is used as the driving TFT.
It is also applicable to the configuration using the FT. Figure 32
The structure is shown in (A).

The driving TFT 3210 is an N-channel type, in which case the source region is the side connected to the anode of the EL element 3215, and the drain region is the TFT 32.
11 is the side connected to the current supply line 3214 through 11. Therefore, the capacitor means 3212 and 3213 are provided at a node that can hold the gate-source voltage of the driving TFT 3210.

The operation will be described. As shown in FIG. 32B, first, the other TFTs are turned on so that the driving TFT 3208 is turned on. Subsequently, as shown in FIG. 32C, when the TFTs 3209 and 3211 are turned off, charges move as shown in the figure until the gate-source voltage of the driving TFT 3208 becomes equal to its threshold voltage.
Eventually, the driving TFT 3208 turns off. At this time,
The capacitor 3212 holds the threshold voltage of the driving TFT 32080.

Then, as shown in FIG. 32D, a video signal is input. The threshold voltage previously held in the capacitance means 3212 is added to this video signal and input to the gate of the driving TFT 3208, and current is supplied according to the gate-source voltage of the driving TFT 3208 at this time. A current is supplied from the line 3214 to the EL element 3215. Therefore, even if the threshold voltage of the driving TFT 3208 varies in the adjacent pixels, the threshold voltage is added to the video signal by the capacitor means 3212 regardless of the variation, so that the gate / source of the driving TFT The inter-electrode voltage does not vary between adjacent pixels.

Further, the EL element 3 having the structure shown in FIG.
When 215 is deteriorated by light emission, the voltage between the anode and the cathode rises. As a result, normally the driving TFT
There is a problem that the potential of the source region of 3208 rises, and as a result, the gate-source voltage at the time of light emission decreases, but according to the configuration shown in this embodiment,
When the threshold voltage is acquired in FIGS. 32B to 32C, the potential of the source region of the driving TFT 3208 is turned on by turning on the TFT 3209.
It is fixed at a potential of 6. Therefore, as described above, the driving T
Since the gate-source voltage of the FT3208 does not decrease, it is possible to suppress a decrease in luminance over time.

In this embodiment, the driving TFT 3 is used.
210 is an N-channel type. Other TFT is ON
Since it is used as a switch element that only controls OFF, its polarity does not matter. In addition, the TFT 3207,
Since the 3208 has the same ON and OFF timings, the gate signal line is shared, but the control of the switch element is not limited to this.

Further, the TFT 2711 is the EL element 321.
It can also be used as an erasing TFT for shutting off the current supply to 5 at an arbitrary timing.

Example 14 Since the light emitting device using the light emitting element is a self-luminous type, it has better visibility in a bright place and a wider viewing angle than a liquid crystal display. Therefore, it can be used for a display unit of various electronic devices.

As electronic equipment using the light emitting device of the present invention, a video camera, a digital camera, a goggle type display (head mount display), a navigation system, a sound reproducing device (car audio, audio component system, etc.), a notebook type personal computer, A game device, a mobile information terminal (a mobile computer, a mobile phone, a portable game machine, an electronic book, or the like), an image reproducing device provided with a recording medium (specifically, a Digital Versatile Disc).
(DVD) and other recording media, and a device equipped with a display capable of displaying the image). In particular,
It is desirable to use a light emitting device for a portable information terminal that often sees a screen from an oblique direction, since a wide viewing angle is important. Specific examples of these electronic devices are shown in FIGS.

FIG. 17A shows a light emitting element display device, which includes a housing 3001, a support 3002, a display portion 3003, a speaker portion 3004, a video input terminal 3005, and the like. The light emitting device of the present invention can be used for the display portion 3003. Since the light-emitting device is a self-luminous type, it does not require a backlight and can have a thinner display portion than a liquid crystal display. In addition, the light emitting element display device is for a personal computer, a TV
It includes all display devices for displaying information such as broadcast reception and advertisement display.

FIG. 17B shows a digital still camera including a main body 3101, a display section 3102, an image receiving section 3103,
An operation key 3104, an external connection port 3105, a shutter 3106 and the like are included. The light emitting device of the present invention includes a display unit 310.
2 can be used.

FIG. 17C shows a laptop personal computer, which has a main body 3201, a housing 3202, and a display portion 32.
03, keyboard 3204, external connection port 3205,
A pointing mouse 3206 and the like are included. The light emitting device of the present invention can be used for the display portion 3203.

FIG. 17D shows a mobile computer, which has a main body 3301, a display portion 3302, and a switch 330.
3, operation keys 3304, infrared port 3305 and the like. The light emitting device of the present invention can be used for the display portion 2302.

FIG. 17 (E) shows a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium.
401, housing 3402, display unit A3403, display unit B3
404, a recording medium (DVD or the like) reading unit 3405, operation keys 3406, a speaker unit 3407, and the like. Display A3
403 mainly displays image information, and a display unit B3404
Mainly displays character information, but the light emitting device of the present invention can be used for these display portions A, B3403, 3404. Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 17F shows a goggle type display (head mount display), which includes a main body 3501, a display portion 3502 and an arm portion 3503. The light emitting device of the present invention can be used for the display portion 3502.

FIG. 17G shows a video camera, which is a main body 3
601, display unit 3602, housing 3603, external connection port 3604, remote control receiving unit 3605, image receiving unit 360
6, a battery 3607, a voice input unit 3608, operation keys 3609, an eyepiece unit 3610, and the like. The light emitting device of the present invention can be used for the display portion 3602.

FIG. 17H shows a mobile phone, which is a main body 370.
1, housing 3702, display unit 3703, voice input unit 370
4, a voice output unit 3705, operation keys 3706, an external connection port 3707, an antenna 3708, and the like. The light emitting device of the present invention can be used for the display portion 3703. Note that the display portion 3703 can suppress current consumption of the mobile phone by displaying white characters on a black background.

If the emission brightness of the organic light emitting material becomes higher in the future, it is possible to magnify and project the output light containing the image information with a lens or the like and use it for a front type or rear type projector.

Further, the electronic equipment is the Internet or C
Information distributed through electronic communication lines such as ATV (cable television) is often displayed, and in particular, opportunities for displaying moving image information are increasing. Since the response speed of the organic light emitting material is very high, the light emitting device is suitable for displaying moving images.

Since the light emitting device consumes power in the light emitting portion, it is desirable to display information so that the light emitting portion is reduced as much as possible. Therefore, when a light emitting device is used in a display unit mainly for character information such as a mobile information terminal, a mobile phone or a sound reproducing device, it is driven so that the character information is formed in the light emitting portion with the non-light emitting portion as the background. It is desirable to do.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be applied to electronic devices in all fields. In addition, the electronic apparatus of this embodiment may use the light emitting device having any of the configurations shown in Embodiments 1 to 13.

According to the present invention, the variation in the threshold value of the TFT for each pixel can be corrected normally without being affected by the variation in the capacitance value of the capacitance means. Further, since the period for charging the electric charge and the period for selecting the gate signal line and writing the video signal in the pixel can be provided independently, each operation can be performed with a sufficient time margin. Is. Therefore, high-speed operation of the circuit is possible, and particularly when displaying with a method that combines the digital gradation method and the time gradation method, it is possible to display high-quality video using a video signal with a higher number of bits. Becomes

Compared with the conventional example, it is based on a simpler operating principle, and since the number of elements and the like do not increase significantly, there is no concern that the aperture ratio will decrease, and it can be said that it is very effective.

[Brief description of drawings]

FIG. 1 is a diagram showing one mode of a pixel structure in a light emitting device of the invention.

FIG. 2 is a diagram illustrating driving of the pixel shown in FIG.

FIG. 3 is a diagram showing a configuration example of a pixel of a light emitting device which is generally used.

FIG. 4 is a diagram showing a configuration of a pixel when driven by a time gray scale method using a digital video signal.

FIG. 5 is a diagram showing a pixel configuration capable of correcting threshold variation.

6A and 6B are diagrams illustrating driving of the pixel illustrated in FIG.

FIG. 7 is a diagram showing a configuration example of a light emitting device of an analog video signal input system which is an embodiment of the present invention.

8 is a diagram showing a configuration example of a source signal line driver circuit and a gate signal line driver circuit in the light emitting device shown in FIG.

FIG. 9 is a diagram showing a configuration example of a light emitting device of a digital video signal input system which is an embodiment of the present invention.

10 is a diagram showing a configuration example of a source signal line driver circuit in the light emitting device shown in FIG.

11 is a diagram showing a configuration example of a gate signal line driver circuit having a different configuration from FIG.

12 is a diagram illustrating pulse output timing of the gate signal line driver circuit illustrated in FIG.

FIG. 13 is a diagram showing an example of a manufacturing process of a light emitting device.

FIG. 14 is a diagram showing an example of a manufacturing process of a light emitting device.

FIG. 15 is a diagram showing an example of a manufacturing process of a light emitting device.

16A and 16B are an external view and a cross-sectional view of a light-emitting device.

FIG. 17 is a diagram showing an example of an electronic device to which the present invention can be applied.

FIG. 18 is a diagram showing an example of a pixel configuration in a light emitting device of the invention.

19 is a diagram illustrating driving of the pixel shown in FIG.

20A and 20B are diagrams showing an embodiment and operation of a pixel configuration in a light emitting device of the invention.

21A and 21B are diagrams showing an example and operation of a pixel structure in a light emitting device of the invention.

22A and 22B are diagrams showing an embodiment and operation of a pixel structure in a light emitting device of the invention.

FIG. 23 is a diagram showing a variation of the pixel configuration shown in FIG. 22.

FIG. 24 is a diagram showing a timing chart of gate signal lines in the case where a light-emitting device having a pixel of the present invention is driven by a digital time gray scale method.

25 is a diagram showing a configuration of a gate signal line drive circuit for outputting a pulse to a gate signal line according to the timing chart of FIG.

FIG. 26 is a diagram for explaining the operation principle of the present invention.

FIG. 27 is a diagram showing an example of configuring a current source circuit using the threshold value correction principle of the present invention.

FIG. 28 is a diagram showing an example of configuring a current source circuit using the threshold value correction principle of the present invention.

FIG. 29 is a diagram showing an example of configuring a current source circuit using the threshold value correction principle of the present invention.

FIG. 30 is a diagram showing an example of configuring a current source circuit using the threshold value correction principle of the present invention.

FIG. 31 is a diagram showing an example of configuring a current source circuit using the threshold value correction principle of the present invention.

32A and 32B are diagrams showing an example and operation of a pixel configuration in a light emitting device of the invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 29/786 H05B 33/14 A H05B 33/14 H01L 29/78 614 618C F term (reference) 3K007 AB03 AB17 BA06 DB03 GA00 5C080 AA06 BB05 DD05 DD28 EE28 FF11 JJ02 JJ03 JJ04 JJ06 5F110 AA30 BB02 BB04 CC02 DD01 DD02 DD03 DD05 DD13 DD14 DD15 DD17 EE01 EE02 EE03 EE04 EE06 EE09 EE11 EE14 EE23 EE44 EE45 FF02 FF04 FF09 FF28 FF30 FF36 GG01 GG02 GG13 GG15 GG25 GG26 GG32 GG43 GG45 GG47 GG51 HJ01 HJ04 HJ12 HJ13 HJ23 HL01 HL02 HL03 HL04 HL07 HL11 HL12 HL23 HM15 NN03 NN04 NN22 NN24 NN27 NN28 NN34 NN35 NN36 NN71 NN72 PP01 PP02 PP03 PP04 PP05 PP06 PP10 PP29 PP34 PP35 QQ04 QQ11 QQ19 QQ23 QQ24 QQ25 QQ28

Claims (29)

[Claims] 1. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has at least a current supply line, first to fourth transistors, and a capacitance means, The gate electrode of the transistor is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the first electrode is electrically connected to the current supply line; The second electrode is electrically connected to the second electrode of the second transistor and the first electrode of the third transistor, and the gate electrode of the second transistor has a first signal A second signal is input to a gate electrode of the third transistor, a second electrode of the capacitance means is electrically connected to a first electrode of the fourth transistor, The gate of the fourth transistor A third signal is input to the first electrode, and the second electrode is configured to be electrically connected to the current supply line. 2. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to fifth The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is the first electrode of the third transistor. And electrical connection with the gate electrode of the fifth transistor The gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor and the fifth electrode. Electrically connected to a first electrode of a transistor, a gate electrode of the fourth transistor electrically connected to the fourth gate signal line, and a second electrode of the first electrode of the light emitting element. A light emitting device, wherein the light emitting device is electrically connected to an electrode, and the second electrode of the fifth transistor is electrically connected to the current supply line. 3. A light emitting device having a pixel provided with a light emitting element, wherein the pixel is a source signal line, first to third gate signal lines, a current supply line, and first to fifth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is the first electrode of the third transistor. And electrical connection with the gate electrode of the fifth transistor The gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the first electrode of the fourth transistor and the fifth electrode. Electrically connected to a first electrode of the transistor, a gate electrode of the fourth transistor electrically connected to the third gate signal line, and a second electrode of the first electrode of the light emitting element. A light emitting device, wherein the light emitting device is electrically connected to an electrode, and the second electrode of the fifth transistor is electrically connected to the current supply line. 4. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to fifth The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode and the gate electrode of the fifth transistor, the gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode Is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is electrically connected to the fourth gate signal line. The light-emitting device is connected, and the second electrode is electrically connected to the current supply line. 5. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to third gate signal lines, a current supply line, and first to fifth The transistor, the capacitor means, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor Is electrically connected to the first electrode and the gate electrode of the fifth transistor, the gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode Is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is electrically connected to the third gate signal line. The light-emitting device is connected, and the second electrode is electrically connected to the current supply line. 6. A light emitting device having a pixel provided with a light emitting element, wherein the pixel is a source signal line, first to fifth gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is the first electrode of the third transistor. And electrical connection with the gate electrode of the fifth transistor The gate electrode of the third transistor is electrically connected to the third gate signal line, and the second electrode is the first electrode of the fourth transistor and the fifth electrode. Electrically connected to a first electrode of a transistor, a gate electrode of the fourth transistor electrically connected to the fourth gate signal line, and a second electrode of the first electrode of the light emitting element. Electrically connected to an electrode, a second electrode of the fifth transistor electrically connected to the current supply line, and a gate electrode of the sixth transistor electrically connected to the fifth gate signal line. And the first electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor. 7. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to sixth The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the current supply line, and the second electrode of the capacitance means is the first electrode of the third transistor. And electrical connection with the gate electrode of the fifth transistor The gate electrode of the third transistor is electrically connected to the second gate signal line, and the second electrode is the first electrode of the fourth transistor and the fifth electrode. Electrically connected to a first electrode of the transistor, a gate electrode of the fourth transistor electrically connected to the third gate signal line, and a second electrode of the first electrode of the light emitting element. Electrically connected to an electrode, a second electrode of the fifth transistor electrically connected to the current supply line, and a gate electrode of the sixth transistor electrically connected to the fourth gate signal line. And the first electrode is electrically connected to the first electrode of the third transistor or the second electrode of the third transistor. 8. A light emitting device having a pixel provided with a light emitting element, wherein the pixel is a source signal line, first to fourth gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the third gate signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the fourth transistor and the second electrode of the fifth transistor, and the gate electrode of the fourth transistor is electrically connected. Electrically connected to the fourth gate signal line, a second electrode electrically connected to the first electrode of the light emitting element, and a second electrode of the sixth transistor connected to the current A light-emitting device, which is electrically connected to a supply line. 9. A light emitting device having a pixel provided with a light emitting element, wherein the pixel includes a source signal line, first to third gate signal lines, a current supply line, and first to sixth pixels. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the second gate signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the fourth transistor and the second electrode of the fifth transistor, and the gate electrode of the fourth transistor is electrically connected. Electrically connected to the third gate signal line, a second electrode electrically connected to the first electrode of the light emitting element, and a second electrode of the sixth transistor connected to the current A light-emitting device, which is electrically connected to a supply line. 10. A light emitting device having a pixel provided with a light emitting element, wherein the pixel is a source signal line, first to fourth gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is the third gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The first electrode is electrically connected to the fourth gate signal line, the first electrode is electrically connected to the second electrode of the sixth transistor, and the second electrode is electrically connected to the current supply line. A light-emitting device characterized by being connected to. 11. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to third gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the second gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The third electrode is electrically connected to the third gate signal line, the first electrode is electrically connected to the second electrode of the sixth transistor, and the second electrode is electrically connected to the current supply line. A light-emitting device characterized by being connected to. 12. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is the third gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The second electrode is electrically connected to the fourth gate signal line, the second electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the sixth transistor is A light-emitting device, which is electrically connected to a current supply line. 13. A light emitting device having a pixel provided with a light emitting element, wherein the pixel is a source signal line, first to third gate signal lines, a current supply line, and first to sixth. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the second gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The second electrode is electrically connected to the third gate signal line, the second electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the sixth transistor is A light-emitting device, which is electrically connected to a current supply line. 14. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fifth gate signal lines, a current supply line, and first to seventh. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is the third gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The first electrode is electrically connected to the fourth gate signal line, the first electrode is electrically connected to the second electrode of the sixth transistor, and the second electrode is electrically connected to the current supply line. The gate electrode of the seventh transistor is electrically connected to the fifth gate signal line, and the first electrode is the first electrode of the third transistor or the third electrode of the third transistor. Second electrode of transistor and electricity A light-emitting device characterized in that they are electrically connected. 15. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to seventh lines. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is The second electrode is electrically connected to the second gate signal line, the second electrode is electrically connected to the first electrode of the fifth transistor and the first electrode of the sixth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the second gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The third electrode is electrically connected to the third gate signal line, the first electrode is electrically connected to the second electrode of the sixth transistor, and the second electrode is electrically connected to the current supply line. The gate electrode of the seventh transistor is electrically connected to the fourth gate signal line, and the first electrode is the first electrode of the third transistor or the third electrode. Second electrode of transistor and electricity A light-emitting device characterized in that they are electrically connected. 16. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fifth gate signal lines, a current supply line, and first to seventh pixels. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is the third gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The second electrode is electrically connected to the fourth gate signal line, the second electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the sixth transistor is The gate electrode of the seventh transistor is electrically connected to the current supply line, the gate electrode of the seventh transistor is electrically connected to the fifth gate signal line, and the first electrode is the first electrode of the third transistor. Alternatively, the third tiger Emitting apparatus characterized by being the second electrode and electrically connected to the register. 17. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to seventh. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the capacitance means and the first electrode of the second transistor, and the gate electrode of the second transistor is A second electrode electrically connected to the second gate signal line, a second electrode electrically connected to the first electrode of the fourth transistor and a first electrode of the fifth transistor, and the capacitor The second electrode of the means is the third transistor. Electrically connected to the first electrode of the third transistor, the gate electrode of the fifth transistor, and the gate electrode of the sixth transistor, and the gate electrode of the third transistor is connected to the second gate signal line. The second electrode is electrically connected to the second electrode of the fifth transistor and the first electrode of the light emitting element, and the gate electrode of the fourth transistor is The second electrode is electrically connected to the third gate signal line, the second electrode is electrically connected to the first electrode of the sixth transistor, and the second electrode of the sixth transistor is The gate electrode of the seventh transistor is electrically connected to a current supply line, the gate electrode of the seventh transistor is electrically connected to the fourth gate signal line, and the first electrode is the first electrode of the third transistor. Alternatively, the third tiger Emitting apparatus characterized by being the second electrode and electrically connected to the register. 18. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fifth gate signal lines, a current supply line, and first to seventh. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the second transistor, the first electrode of the sixth transistor, and the first electrode of the capacitance means. A gate electrode of the second transistor is electrically connected to the second gate signal line, a second electrode is electrically connected to the current supply line, a second electrode of the capacitance means Is the first electrode of the third transistor and the fifth electrode A gate electrode of a transistor, the gate electrode of the sixth transistor and a second electrode, and a gate electrode of the third transistor electrically connected to the third gate signal line, The second electrode is electrically connected to the first electrode of the fourth transistor and the first electrode of the fifth transistor, and the gate electrode of the fourth transistor is the fourth gate. The second electrode is electrically connected to the signal line, the second electrode is electrically connected to the first electrode of the light emitting element, and the second electrode of the fifth transistor is electrically connected to the current supply line. The seventh transistor is connected between the second electrode of the first transistor and the first electrode of the sixth transistor, the first electrode of the third transistor and the sixth transistor. Second It is provided either between the electrode and between the first electrode of the third transistor and the gate electrode of the sixth transistor, and the gate electrode is electrically connected to the fifth gate signal line. A light-emitting device characterized in that they are electrically connected. 19. A light emitting device having a pixel provided with a light emitting element, wherein the pixel has a source signal line, first to fourth gate signal lines, a current supply line, and first to seventh lines. The transistor, the capacitor, and the light emitting element, the gate electrode of the first transistor is electrically connected to the first gate signal line, and the first electrode is the source signal line. Electrically connected, the second electrode is electrically connected to the first electrode of the second transistor, the first electrode of the sixth transistor, and the first electrode of the capacitance means. A gate electrode of the second transistor is electrically connected to the second gate signal line, a second electrode is electrically connected to the current supply line, a second electrode of the capacitance means Is the first electrode of the third transistor and the fifth electrode A gate electrode of a transistor, a gate electrode of the sixth transistor, and a second electrode, and a gate electrode of the third transistor electrically connected to the second gate signal line, The second electrode is electrically connected to the first electrode of the fourth transistor and the first electrode of the fifth transistor, and the gate electrode of the fourth transistor is the third gate. The second electrode is electrically connected to the signal line, the second electrode is electrically connected to the first electrode of the light emitting element, and the second electrode of the fifth transistor is electrically connected to the current supply line. The seventh transistor is connected between the second electrode of the first transistor and the first electrode of the sixth transistor, the first electrode of the third transistor and the sixth transistor. Second It is provided either between the electrode and between the first electrode of the third transistor and the gate electrode of the sixth transistor, and the gate electrode is electrically connected to the fourth gate signal line. A light-emitting device characterized in that they are electrically connected. 20. Claim 3, claim 5, claim 7, claim 9, claim 11, claim 13, claim 15, claim 1.
20. The light emitting device according to claim 7, wherein the second transistor and the third transistor have the same polarity. 21. The light emitting device according to claim 8, wherein the fifth transistor has a gate length of L ₁ , a channel width of W _1, and a gate of the sixth transistor. The length is L ₂ ,
A light emitting device characterized in that (W ₁ / L ₁ )> (W ₂ / L ₂ ) holds when the channel width is W ₂ . 22. The light emitting device according to claim 18, wherein the fifth transistor has a gate length of L ₁ , the channel width is W _1, and the sixth transistor has a gate length of L ₂ .
A light-emitting device characterized in that (W ₁ / L ₁ ) <(W ₂ / L ₂ ), when the channel width is W ₂ . 23. The light emitting device according to claim 6 or 7, wherein the second electrode of the sixth transistor controls a power supply line having a potential difference from the current supply line or the pixel. A light emitting device, which is electrically connected to any one of the gate signal lines except the gate signal line. 24. Any one of claims 14 to 17
In the light-emitting device according to the item, the second electrode of the seventh transistor is a power supply line having a potential difference from the current supply line or any one gate except the gate signal line for controlling the pixel. A light emitting device, which is electrically connected to a signal line. 25. The light emitting device according to claim 1, wherein the second electrode of the light emitting element is electrically connected to a power supply line having a potential difference with the current supply line. A light-emitting device characterized by being provided. 26. The pixel according to any one of claims 1 to 25, wherein the pixel has a storage capacitor means, and a first electrode of the storage capacitor means has a second electrode of the first transistor. A light-emitting device, which is electrically connected to an electrode, is supplied with a constant potential to a second electrode, and holds a video signal input from a source signal line in the previous period. 27. A pixel provided with a light emitting element, wherein the pixel includes a source signal line, a current supply line, a transistor for supplying a desired current to the light emitting element, a light emitting element, and a capacitor. A method of driving a light emitting device having the first step of: storing a charge in the capacitance means; and a second step of converging a voltage between both electrodes of the capacitance means to a voltage equal to a threshold voltage of the transistor. And a third step of inputting a video signal from the source signal line, and applying the threshold voltage to the potential of the video signal and applying the threshold voltage to the gate electrode of the transistor through the transistor. A fourth step of supplying an electric current to the light emitting element to emit light, a voltage between both electrodes of the capacitance means being constant in at least the third step, In the first and second step, the first transistor is a driving method of a light-emitting device characterized by a non-conductive state. 28. A pixel provided with a light emitting element, wherein the pixel has at least a current supply line, first to third transistors, and capacitance means, and a gate electrode of the first transistor. Is electrically connected to the first electrode of the second transistor and the first electrode of the capacitance means, the first electrode is electrically connected to the current supply line, and the second electrode Is electrically connected to a second electrode of the second transistor and a first electrode of the third transistor, a first signal is input from a gate electrode of the second transistor, A second signal is input from the gate electrode of the third transistor, the second electrode of the capacitance means is electrically connected to the first electrode of the fourth transistor, and the second electrode of the capacitance means is connected to the first electrode of the fourth transistor. Video signal from 2 electrodes A third signal is input from the gate electrode of the fourth transistor, and the second electrode is electrically connected to the current supply line. A first step of inputting a first to a third signal to make the second to fourth transistors conductive, thereby accumulating charges in the capacitance means; and making the third transistor non-conductive, and First,
A second signal for inputting a third signal to bring the second and fourth transistors into conduction so that the voltage held in the capacitance means converges to a value equal to the threshold voltage of the first transistor. And a third step in which the second to fourth transistors are made non-conductive, and the video signal is inputted from the second electrode of the capacitance means, and the second and fourth transistors are made non-conductive. A fourth step in which current is made to flow between the source and drain of the first and third transistors by making them conductive and by making the third transistor conductive by inputting the second signal, At least in the third step, the method for driving a light emitting device, wherein the voltage between both electrodes of the capacitance means is constant. 29. An electronic device using the light emitting device according to claim 1 or the method for driving a light emitting device according to claim 27 or 28.