JP2003234188A - Display device and electronic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active matrix type EL display device of which, the number of external power sources is reduced by arranging a power source for EL driving at its inside. <P>SOLUTION: A power circuit for EL drive is constituted by transistors formed on a substrate, and in the case that the output circuit composition is made to drive a positive electrode of OLED, p-channel type transistors of grounded- source are chosen. By making it such composition, the difference of power source voltage and output voltage can be reduced, and the power circuit of small power consumption can be constituted. Moreover, the above power circuit is turned into a power circuit using an operational amplifier. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a display device. In particular, it relates to an OLED display device using a thin film transistor formed on a transparent substrate such as glass or plastic. Further, the invention relates to an electronic device using the display device.

[0002]

2. Description of the Related Art In recent years, mobile phones have become widespread due to the development of communication technology. In the future, it is expected that video will be transmitted more and more information will be transmitted. On the other hand, the weight reduction of personal computers has led to the production of mobile-compatible products. A large number of information devices called personal digital assistants (PDAs), which started with electronic notebooks, have been produced and are becoming popular. Further, due to the development of display devices and the like, most of these portable information devices are equipped with a flat display.

In more recent technology, an active matrix type display device is being used as a display device used for them.

In the active matrix type display device, a TFT (thin film transistor) is arranged for each pixel, and the screen is controlled by the TFT. Such an active matrix display device has advantages such as higher definition, improved image quality, and moving image support, as compared with the passive matrix display device. Therefore, it is expected that the display device of portable information equipment will change from the passive matrix type to the active matrix type in the future.

In addition, among active matrix type display devices, in recent years, display devices using low temperature polysilicon have been commercialized. In the low-temperature polysilicon technology, in addition to the pixel TFT which constitutes a pixel, the T
A driving circuit can be formed at the same time by using FT, which greatly contributes to downsizing of the device and low power consumption. Along with this, a low temperature poly Silicon display devices are becoming indispensable devices.

Further, in recent years, the development of a display device using an organic electroluminescence element (OLED element) has become active. Here, the OLED element includes both an element that uses light emission (fluorescence) from singlet excitons and an element that uses light emission (phosphorescence) from triplet excitons.
Although an OLED element is given as an example of the light emitting element in this specification, other light emitting elements may be used.

The OLED element is a pair of electrodes (cathode and anode).
The OLED layer is sandwiched between the two, and usually has a laminated structure. A typical example is the laminated structure (hole transport layer / light emitting layer / electron transport layer) proposed by Tang of Eastman Kodak Company.

In addition to these (hole injection layer, hole transport layer,
There is a structure in which (light emitting layer / electron transport layer) or (hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer) is laminated in this order. In the present invention, any one may be adopted, and the light emitting layer may be doped with a fluorescent dye.

In this specification, all layers provided between the anode and the cathode are collectively referred to as an OLED layer. Therefore, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer,
The electron injection layer is entirely included in the OLED layer. Anode, OL
A light emitting element composed of an ED layer and a cathode is called an OLED element.

FIG. 3 shows an active matrix OLED.
An example of a structure of a pixel portion of a display device is shown. Gate signal lines (G1 to G) for inputting selection signals from the gate signal line drive circuit
y) is connected to the gate electrode of the switching TFT 301 included in each pixel. In addition, one of a source region and a drain region of the switching TFT 301 included in each pixel is a source signal line (S1 to Sx) to which a signal is input from a source signal line driver circuit, and the other is an OLED driving T.
It is connected to the gate electrode of the FT 302 and one electrode of a capacitor 303 included in each pixel. Capacitor 30
The other electrode of 3 is connected to the power supply lines (V1 to Vx). OLED driving TFT 3 of each pixel
One of the source region and the drain region of 02 is connected to the power supply lines (V1 to Vx), and the other is connected to one electrode of the OLED element 304 included in each pixel.

The OLED element 304 includes an anode, a cathode, and
An OLED layer provided between the anode and the cathode. O
The anode of the LED element 304 is the OLED driving TFT 302.
When connected to the source or drain region of
The anode of the OLED element 304 serves as a pixel electrode and the cathode serves as a counter electrode. Conversely, when the cathode of the OLED element 304 is connected to the source region or the drain region of the OLED driving TFT 302, the cathode of the OLED element 304 serves as a pixel electrode and the anode serves as a counter electrode.

In the present specification, the potential of the counter electrode is called the counter potential. A power supply that applies a counter potential to the counter electrode is called a counter power supply. The potential difference between the pixel electrode potential and the counter electrode potential is the OLED drive voltage, and this OLED drive voltage is applied to the OLED layer.

The gradation display method of the OLED display device includes an analog gradation method and a time gradation method.

Regarding such a driving method, Patent Document 1 which discloses the structure of an active matrix type display device is disclosed.
Is shown in.

[0015]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-343933

First, the analog gradation method of the OLED display device will be described. FIG. 4 shows a timing chart when the display device shown in FIG. 3 is driven by the analog gradation method. A period from the selection of one gate signal line to the selection of the next gate signal line is called one line period (L). A period from the selection of one image to the selection of the next image corresponds to one frame period. In the case of the OLED display device of FIG. 3, since there are y gate signal lines, y line periods (L1 to Ly) are provided in one frame period.

As the resolution becomes higher, the number of line periods in one frame period also increases, and the driving circuit has to be driven at a high frequency.

The power supply lines (V1 to Vx) are kept at a constant potential (power supply potential). The opposing potential is also kept constant. The opposite potential has a potential difference with the power supply potential to the extent that the OLED element emits light.

In the first line period (L1), the selection signal from the gate signal line drive circuit is input to the gate signal line G1. Then, analog video signals are sequentially input to the source signal lines (S1 to Sx).

Since all the switching TFTs 301 connected to the gate signal line G1 are turned on, the analog video signal input to the source signal lines (S1 to Sx) is OLED through the switching TFT 301.
It is input to the gate electrode of the driving TFT 302.

When the switching TFT 301 is turned on, the gate voltage of the OLED driving TFT 302 changes according to the potential of the analog video signal input into the pixel. At this time, Id-Vg of the OLED driving TFT 302
Drain current is 1: 1 with respect to gate voltage according to characteristics
Depends on. That is, the potential of the drain region (the OLED drive potential of ON) is determined corresponding to the potential of the analog video signal input to the gate electrode of the OLED drive TFT 302, and a predetermined drain current flows through the OLED element, and the current The OLED element emits light with a light emission amount corresponding to the amount.

When the input of the analog video signal to the source signal lines (S1 to Sx) is finished by repeating the above-mentioned operation, the first line period (L1) is finished. In addition,
The period until the input of the analog video signal to the source signal lines (S1 to Sx) is completed and the horizontal retrace period may be combined to form one line period. Then, next, in the second line period (L2), the selection signal is input to the gate signal line G2. Then, similarly to the first line period (L1), analog video signals are sequentially input to the source signal lines (S1 to Sx).

And all the gate signal lines (G1 to Gy)
When a selection signal is input to, all line periods (L1 to
Ly) ends. When all the line periods (L1 to Ly) end, one frame period ends. All pixels display during one frame period and one image is formed. Note that all the line periods (L1 to Ly) and the vertical blanking period may be combined to form one frame period.

As described above, the light emission amount of the OLED element is controlled by the analog video signal, and gradation display is performed by controlling the light emission amount. As described above, in the analog gradation method, gradation display is performed by a change in the potential of the analog video signal input to the source signal line.

Next, the time gray scale method will be described.

In the time gray scale method, a digital signal is input to a pixel to select a light emitting state or a non-light emitting state of the OLED element, and a gray scale is expressed by a total of the periods in which the OLED element emits light per one frame period. .

Here, a case of expressing 2 ⁿ (n is a natural number) gradation will be described. FIG. 5 shows a timing chart when the display device shown in FIG. 3 is driven by this time gray scale method. First, one frame period is divided into _n subframe periods (SF _{1 to} SF _n ). Note that a period in which all the pixels in the pixel portion display one image is referred to as one frame period (F). In addition, a period obtained by further dividing one frame period into a plurality of periods is called a subframe period. As the number of gradations increases, the number of divisions in one frame period also increases, and the drive circuit must be driven at a high frequency.

One sub-frame period is divided into a writing period (Ta) and a display period (Ts). The writing period is a period in which a digital signal is input to all pixels in one subframe period, and the display period (also referred to as a lighting period) is a state in which an OLED element emits light or does not emit light depending on the input digital signal. The period during which the display is performed is shown.

The OLED drive voltage shown in FIG. 5 represents the OLED drive voltage of the OLED element whose light emitting state is selected. That is, the OLED drive voltage (FIG. 3) of the OLED element whose light emitting state is selected is 0 V during the writing period, and has a magnitude such that the OLED element emits light during the display period.

The opposite potential is controlled by an external switch (not shown), the opposite potential is maintained at almost the same level as the power supply potential during the writing period, and the OLED element emits light during the display period with the power supply potential. Has a potential difference of.

First, the writing period and the display period of each sub-frame period will be described in detail with reference to FIGS. 3 and 5, and then the time gray scale display will be described.

First, a gate signal is input to the gate signal line G1, and all the switching TFTs 301 connected to the gate signal line G1 are turned on. Then, digital signals are sequentially input to the source signal lines (S1 to Sx). The opposite potential is kept at the same height as the potential (power supply potential) of the power supply lines (V1 to Vx). The digital signal has information of "0" or "1". The digital signals of "0" and "1" mean signals having a voltage of either Hi or Lo, respectively.

The digital signal input to the source signal lines (S1 to Sx) is the switching T in the ON state.
It is input to the gate electrode of the OLED driving TFT 302 via the FT 301. A digital signal is also input and held in the capacitor 303.

Then, the above-described operation is repeated by sequentially inputting the gate signal to the gate signal lines G2 to Gy, the digital signal is input to all the pixels, and the digital signal input to each pixel is held. A period until a digital signal is input to all pixels is called a writing period.

When the digital signal is input to all the pixels, all the switching TFTs 301 are turned off. Then, by an external switch (not shown) connected to the counter electrode, the counter potential is changed so as to have a potential difference with the power supply potential such that the OLED element 304 emits light.

When the digital signal has information "0", the OLED driving TFT 302 is turned off and the OLED element 304 does not emit light. On the contrary, when the information of “1” is included, the OLED driving TFT 302 is turned on. As a result, the pixel electrode of the OLED element 304 is kept substantially equal to the power supply potential, and the OLED element 304 emits light. As described above, the light emitting state or the non-light emitting state of the OLED element is selected according to the information included in the digital signal, and all the pixels display at the same time. An image is formed by displaying all the pixels. A period in which a pixel displays is called a display period.

N subframe periods (SF _{1 to} SF _n )
There are all the same length of the writing period, each having (Ta ₁ ~Ta _n). The display periods (Ts) that SF _{1 to} SF _n have are set to Ts ₁ to Ts _n , respectively.

The length of the display period is Ts ₁ : Ts ₂ : T
s ₃ : ...: Ts _(n-1) : Ts _n = 2 ⁰ : 2 ^-1 : 2 ^-2 : ...: 2
^(-(n-2)) : Set to be 2 ^(-(n-1)) . With this combination of display periods, it is possible to perform a desired gradation display out of 2 ⁿ gradations.

The display period is any period from Ts ₁ to Ts _n . Here, it is assumed that a predetermined pixel is turned on during the period of Ts ₁ .

Next, the writing period is started again, and when the data signals are input to all pixels, the display period is started. At this time T
Any one of the periods s _{2 to} Ts _n is the display period. Here, it is assumed that a predetermined pixel is turned on during the period of Ts ₂ .

Thereafter, the same operation is repeated for the remaining n-2 sub-frames, and Ts ₃ , Ts ₄ ... Ts _n are sequentially performed.
It is assumed that the display period is set and a predetermined pixel is turned on in each subframe.

When n sub-frame periods appear, one frame period is completed. At this time, the gradation of the pixel is determined by integrating the length of the display period in which the pixel is lit. For example, when n = 8 and the luminance when the pixel emits light in the entire display period is 100%, when the pixel emits light at Ts ₁ and Ts ₂ , it is 75%.
% Luminance can be expressed, and when Ts ₃ , Ts _5, and Ts ₈ are selected, 16% luminance can be expressed.

In the time gray scale driving method in which an n-bit digital signal is input to express gray levels, when one frame period is divided into a plurality of sub frame periods,
The number of divisions, the length of each subframe period, and the like are not limited to the above.

By using a transistor formed of a polycrystalline semiconductor (polysilicon), a pixel and a driving circuit (hereinafter referred to as an internal circuit) are formed on the same insulating surface.
There is a technique for controlling the operation of the internal circuit by connecting the internal circuit to a power circuit or the like via an FPC or the like (see Patent Document 1).

[0045]

The conventional OLED display device described above has the following problems. It is necessary to supply a necessary amount of current in order to cause the OLED element arranged in the pixel portion to emit light. 2 here
When considering an inch OLED panel, the current OLED
Using a material, for example, in order to obtain a brightness of 200 cd / m2, a current of 3.5 mA / cm2 for red, a current of 1 mA / cm2 for green, and a current of 3 mA / cm2 for blue are used.
Therefore, when converted into 2 inches, currents of 14 mA, 4 mA, and 12 mA are required.
In addition, each color is 8V, 5V, 7V for the OLED element.
Is generated. To supply these currents,
As shown in FIG. 2, conventionally, three power supply circuits using a source follower are prepared outside the panel. These power supply circuits have had drawbacks such as an increase in mounting area and an increase in the number of parts.

When a power supply circuit composed of these source followers is used, since the source followers use MOS transistors in the saturation region, Vds (drain-source voltage) increases and power consumption also increases. . For example, when Vds is required to be 5V, Vds of the source follower of the power supply circuit of each color is required to have a voltage of 5V for red, 8V for green, and 6V for blue because VCC is set according to red, which has the highest OLED voltage. Become. When the power consumption of the source follower is calculated by multiplying this by the above-mentioned current, the power of each color is 70 mW, 40 mW, 72
mW of power is generated, requiring a total of 184 mW. Such electric power causes the battery of the portable device to be consumed, and the usage time of the portable device is reduced. Therefore, it has been desired to incorporate a power supply circuit with low power in the panel.

Therefore, an object of the present invention is to incorporate a low power consumption power supply in a display device using an OLED element in order to reduce the mounting area, the cost of individual parts, and the power consumption. Further, the present invention is applicable not only to a display device using an OLED element but also to a display device using another light emitting element. For example, the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer can be used in a display device to which a light emitting element containing an inorganic material is applied.

[0048]

In order to solve the aforementioned problems, the present invention uses the following means.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have an OLED element. In the display device, a current or a voltage is applied to the OLED element. There is provided a display device characterized in that a power supply circuit for emitting light is provided on a substrate.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels emit red, green and blue light.
Provided is a display device having an LED element, characterized in that a power supply circuit for applying a current or a voltage to each of the red, green, and blue OLED elements to emit light is provided on a substrate.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and in the display device having the OLED elements, the pixels have a current or a voltage applied to the OLED elements. There is provided a display device characterized in that a power supply circuit for giving light and emitting light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on the substrate, and the pixels emit red, green and blue light.
In a display device having an LED element, a power supply circuit for applying a current or a voltage to the red, green, and blue OLED elements to emit light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. A display device characterized by the above is provided.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels emit red, green and blue light.
The OLE for each of red, green and blue having an LED element
In a display device in which a power supply circuit for applying current or voltage to the D element to emit light is formed on the substrate, and the power supply circuit is a power supply circuit using an operational amplifier, the OLED element has a common cathode and a power supply. A display device is provided in which an output of the circuit is configured by a source-grounded P-channel transistor.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on the substrate, and the pixels emit red, green and blue light.
The OLE for each of red, green and blue having an LED element
In a display device in which a power supply circuit for applying current or voltage to the D element to emit light is formed on the substrate, and the power supply circuit is a power supply circuit using an operational amplifier, the OLED element has a common anode and a power supply. There is provided a display device characterized in that the output of the circuit is composed of a source-grounded N-channel transistor.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels emit red, green and blue light.
The OLE for each of red, green and blue having an LED element
A power supply circuit for applying current or voltage to the D element to emit light is formed on the substrate, and the power supply circuit is a display device which is a power supply circuit using an operational amplifier, and the OLED element has a common cathode. In a display device in which an output of a power supply circuit is composed of a source-grounded P-channel transistor, the power supply circuit has a difference between a maximum potential and an output potential in the power supply circuit is equal to or less than a threshold value of the P-channel transistor. A display device is provided.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels emit red, green and blue light.
The OLE for each of red, green and blue having an LED element
A power supply circuit for applying current or voltage to the D element to emit light is formed on the substrate, and the power supply circuit is a display device which is a power supply circuit using an operational amplifier, and the OLED element has a common cathode. In a display device in which an output of a power supply circuit is configured by a source-grounded N-channel transistor, the power supply circuit has a difference between a minimum potential and an output potential in the power supply circuit is equal to or less than a threshold value of the N-channel transistor. A display device is provided.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on the substrate, and the pixels emit red, green and blue light.
A display device having an LED element is provided, in which a power supply circuit for supplying current or voltage to two of red, green, and blue is formed on a substrate.

The present invention provides an electronic device using any of the above display devices.

According to the present invention, in a display device in which a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate and the pixels have a light emitting element, a current or a voltage is applied to the light emitting element. There is provided a display device characterized in that a power supply circuit for emitting light is provided on a substrate.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element that emits red, green and blue light. A display device is provided, in which a power supply circuit for applying current or voltage to each of the light emitting elements for red, green, and blue to emit light is formed on a substrate.

According to the present invention, in a display device in which a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate and the pixels have a light emitting element, a current or a voltage is applied to the light emitting element. There is provided a display device characterized in that a power supply circuit for giving light and emitting light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element which emits red, green and blue light. A display device characterized in that a power supply circuit for applying current or voltage to the light emitting elements for each of red, green, and blue to emit light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. Will be provided.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and each pixel has a light emitting element that emits red, green and blue light. In a display device in which a power supply circuit for applying a current or a voltage to the light emitting element for each of green, blue, and blue to emit light is formed, and the power supply circuit is a power supply circuit using an operational amplifier, the light emitting element is a cathode. Is provided in common, and the output of the power supply circuit is constituted by a source-grounded P-channel type transistor.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and each pixel has a light emitting element that emits red, green and blue light. In a display device in which a power supply circuit for applying current or voltage to each of the light emitting elements for green, green, and blue to emit light is formed, and the power supply circuit is a power supply circuit using an operational amplifier, the light emitting element is an anode. Is provided in common, and the output of the power supply circuit is composed of a source grounded N-channel type transistor.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and each pixel has a light emitting element that emits red, green and blue light. A power supply circuit for applying a current or a voltage to the light emitting element for each of green, blue, and blue to emit light, and the power supply circuit is a display device that is a power supply circuit using an operational amplifier, and the light emitting element is In a display device in which the cathode is common and the output of the power supply circuit is composed of a source-grounded P-channel transistor, in the power supply circuit, the difference between the maximum potential and the output potential in the power supply circuit is the threshold of the P-channel transistor. A display device is provided, which is less than or equal to a value.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and each pixel has a light emitting element that emits red, green and blue light. A power supply circuit for applying a current or a voltage to the light emitting element for each of green, blue, and blue to emit light, and the power supply circuit is a display device that is a power supply circuit using an operational amplifier, and the light emitting element is In a display device in which the cathode is common and the output of the power supply circuit is composed of a source-grounded N-channel transistor, in the power supply circuit, the difference between the lowest potential in the power supply circuit and the output potential is the threshold of the N-channel transistor. A display device is provided, which is less than or equal to a value.

According to the present invention, a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element which emits red, green and blue light. Provided is a display device having a power supply circuit for supplying current or voltage to two of red, green, and blue on a substrate.

The present invention provides an electronic device using any of the above display devices.

In the conventional display device, the OL in the pixel is
The current or voltage applied to the ED element is supplied by an external power supply circuit. Therefore, the number of external parts and the board size are increased, which leads to an increase in manufacturing cost. According to the present invention, by incorporating the power supply circuit inside the panel, it is possible to reduce the number of components and the substrate size. The present invention can be applied not only to a display device using an OLED element but also to a display device using another light emitting element.

[0070]

First, an OLED display device of the present invention will be described.

FIG. 1 shows the configuration of the present invention.
In the present invention, the OLED display device is integrally formed on the substrate 101, and not only the pixel portion 105 but also the signal line driving circuit 10 is formed.
2. It has scanning line drive circuits 103 and 104 and a power supply circuit 106. The power supply circuit 106 is composed of three power supply circuits in order to support three colors of red, green, and blue. Figure 6
Shows a concrete example of the power supply circuit. The circuit of FIG. 6 is not a source follower circuit as in the conventional example, but an operational amplifier type power supply circuit, and by configuring an output circuit composed of P-channel transistors in the output stage, the power supply potential and the output potential are It is possible to reduce the voltage difference between the two.

The contents will be specifically described below with reference to FIG. A reference voltage is input to the input terminal 609 from the outside. Since the input impedance of the power supply circuit 601 is very high, the reference voltage is not affected by the power supply circuit 601. Therefore, the reference voltage may be as simple as a combination of a variable resistance and a fixed resistance as shown in FIG. This voltage is applied to the transistor 602
Input to the differential circuit composed of 603 and output terminal 61
When the potential of 1 is low, that is, the gate potential of the transistor 603 is low, the current of the differential circuit is given by the constant current source 607, so that the current of the transistor 602 becomes larger than the current of the transistor 603. Further, since the transistors 604 and 605 form a current mirror circuit, the current of the transistor 604 is equal to that of the transistor 60.
3 equals the current. Therefore, the capacitor 610 is discharged, and the gate potential of the transistor 606 operates in the direction of decreasing,
The transistor 606 allows more current than the constant current 608 to flow, and raises the output potential. In this way, by applying negative feedback, the output potential becomes substantially the same as the input potential. The output transistor 606 is a source-grounded P-channel transistor,
If the operating point of the output transistor is set in the linear region, it can be raised to a potential close to the power supply voltage VDD. That is, it is possible to reduce the difference between the output voltage and the power supply voltage to a voltage equal to or lower than the threshold value of the P-channel transistor. The output terminal 611 of the power supply circuit 601 is the pixel portion 61.
It is connected to the power supply line 2 and supplies a current to the pixel.

Assuming that the difference between the power supply voltage VDD and the output voltage is 1V, the red power supply voltage is 9V (OLED voltage 8V + power supply 1V), assuming the characteristics of the conventional OLED element. At this time, the green differential voltage is 4V and the blue differential voltage is 2V. The power consumption for each color here is 14
mW, 16mW, 24mW, total power consumption is 54
It becomes mW. Considering that the power supply circuit of the source follower type shown in the conventional example was 184 mW, the present invention reduced the power consumption to about one third. As a result, the amount of heat generated is reduced to about one-third, and the power supply circuit can be built in.

In the above description, the red OLED material has a low luminous efficiency and a high green luminous efficiency, but the present invention is not limited to this, and the material characteristics will change in the future and the red color will be low. Even if it is no longer efficient, it can be fully utilized. Further, in the present description, the OLED is premised on the cathode common, but it is also possible to cope with the case where the anode common is realized by adopting a top emission system or the like. In such a case, the output transistor becomes a source-grounded N-channel transistor, and the difference voltage between the GND or the negative power supply and the output potential can be reduced to the threshold value of the N-channel transistor or less. In the circuit in this case, basically, the polarity of the circuit in FIG. 6 may be inverted. Although an OLED display device has been described here, the present invention is applicable not only to a display device using an OLED element but also to a display device using another light emitting element.

[0075]

EXAMPLES Examples of the present invention will be described below.

Example 1 FIG. 7 is an example of a power supply circuit different from the embodiment. In the embodiment, since the output of the differential circuit is directly connected to the output circuit, the impedance seen from the differential circuit may be low. In this embodiment, in order to prevent this, a transistor 712 is provided between the differential circuit composed of the transistors 702 and 703 and the output circuit composed of the source-grounded P-channel transistor 706.
And a buffer circuit composed of a resistor 713.
By adding such a buffer circuit, it becomes possible to prevent a decrease in the impedance of the output stage viewed from the differential circuit. However, as a drawback of this method, the output potential of the differential circuit, that is, the gate potential of the transistor 712 decreases. This causes the transistors 702 and 703 to
6 is too high in the configuration of FIG. 6 and normal operation may not be possible. Therefore, in order to prevent malfunction, it is necessary to lower the differential input voltage of the transistors 702 and 703. As a countermeasure against that, a buffer circuit including transistors 714 and 715 and current sources 716 and 717 is also input to the differential circuit. Is provided to lower the potential of the differential circuit. By taking such measures, the impedance can be increased without causing a malfunction. In such a circuit, even if the current capacity required for the power supply circuit is large, it is possible to supply the power supply circuit with little power supply fluctuation between the input and the output. The output terminal 711 of the power supply circuit 701 is connected to the power supply line of the pixel portion 718 as in the embodiment, and supplies a current to the pixel.

In this embodiment as well as the embodiment,
The OLED is premised on the cathode common, but it can be applied even when the anode common is realized by adopting a top emission system or the like. In such a case, the output transistor is a source-grounded N-channel transistor, and the difference voltage between the GND or negative power supply and the output potential can be made smaller than the threshold value of the N-channel transistor. The circuit in this case basically has the polarity of the circuit of FIG. 7 inverted. Further, the present embodiment is applicable not only to the display device using the OLED element but also to the display device using other light emitting elements.

[Embodiment 2] FIG. 8 shows a case where a red power source is externally attached and other two color power sources are incorporated. In such a case, it is necessary to stabilize the external power source, but since the power sources to be taken into the panel are only for two colors, the power consumption in the panel can be further reduced. Also,
This embodiment can be applied not only to a display device using an OLED element but also to a display device using another light emitting element.

[Embodiment 3] In this embodiment, the OLE of the present invention is used.
A method of simultaneously manufacturing TFTs of a pixel portion of a D display device and a driver circuit portion (source signal line driver circuit, gate signal line driver circuit, power supply circuit) provided around the pixel portion is described. However, in order to simplify the description, a CMOS circuit, which is a basic unit for the drive circuit unit, is illustrated.

First, as shown in FIG. 9A, a substrate 5001 made of glass such as barium borosilicate glass typified by Corning's # 7059 glass or # 1737 glass or aluminoborosilicate glass is oxidized. A base film 5002 made of an insulating film such as a silicon film, a silicon nitride film, or a silicon oxynitride film is formed. For example, a silicon oxynitride film 5002a formed of SiH ₄ , NH ₃ , and N ₂ O by plasma CVD is used for 10 to 20 times.
0 [nm] (preferably 50-100 [nm]) is formed, and a hydrogenated silicon oxynitride film 5002b similarly made of SiH ₄ and N ₂ O is 50-200 [nm] (preferably 100-nm).
It is laminated to have a thickness of 150 [nm]). Although the base film 5002 is shown as a two-layer structure in this embodiment, it may be formed as a single layer film of the insulating film or a structure in which two or more layers are laminated.

The island-shaped semiconductor layers 5003 to 5006 are formed of crystalline semiconductor films obtained by using a laser crystallization method or a known thermal crystallization method for a semiconductor film having an amorphous structure.
The island-shaped semiconductor layers 5003 to 5006 have a thickness of 25 to 8
It is formed with a thickness of 0 [nm] (preferably 30 to 60 [nm]). Although the material of the crystalline semiconductor film is not limited, it is preferably formed of silicon or a silicon germanium (SiGe) solid solution.

To form a crystalline semiconductor film by the laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, YAG laser, or YVO ₄ laser is used.
When these lasers are used, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and is applied to a semiconductor film. The crystallization conditions are appropriately selected by the practitioner, but when an excimer laser is used, the pulse oscillation frequency is 30 [Hz] and the laser energy density is 100 to 400 [mJ / cm ² ] (typically Two
00-300 [mJ / cm ² ]). When a YAG laser is used, its second harmonic is used, the pulse oscillation frequency is set to 1 to 10 [kHz], and the laser energy density is set to 30.
0 to 600 [mJ / cm ² ] (typically 350 to 500 [mJ / c
m ² ]) is good. And the width 100-1000 [μm],
For example, laser light focused in a linear shape at 400 [μm] is irradiated over the entire surface of the substrate, and the overlapping ratio (overlap ratio) of the linear laser light at this time is set to 80 to 98%. As a laser, Japanese Patent Application No. 2001-36530.
You may use CWLC as in 2.

Next, island-shaped semiconductor layers 5003 to 5006
A gate insulating film 5007 is formed to cover. The gate insulating film 5007 is formed by a plasma CVD method or a sputtering method,
It is formed of an insulating film containing silicon with a thickness of 40 to 150 [nm]. In this embodiment, the silicon oxynitride film is formed to a thickness of 120 [nm]. Of course, the gate insulating film is not limited to such a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a laminated structure. For example, when a silicon oxide film is used, TEOS (Tetraethyl Orthosilicat
e) and O ₂ are mixed, reaction pressure 40 [Pa], substrate temperature 30
It can be formed by discharging at a high frequency (13.56 [MHz]) and a power density of 0.5 to 0.8 [W / cm ² ] at 0 to 400 [° C.]. The silicon oxide film thus manufactured can be excellently used as a gate insulating film by subsequent thermal annealing at 400 to 500 [° C.].

Then, a first conductive film 5008 and a second conductive film 5009 for forming a gate electrode are formed over the gate insulating film 5007. In this embodiment, the first conductive film 5008 is formed of Ta to a thickness of 50 to 100 [nm],
The second conductive film 5009 is formed of W to a thickness of 100 to 300 [nm].

The Ta film is formed by the sputtering method, and the Ta target is sputtered with Ar. in this case,
When an appropriate amount of Xe or Kr is added to Ar, the internal stress of the Ta film can be relaxed and the film peeling can be prevented. Also, α
The Ta film of the phase has a resistivity of about 20 [μΩcm] and can be used for the gate electrode, but the Ta film of β phase has a resistivity of about 180 [μΩcm] and is not suitable for the gate electrode. . In order to form an α-phase Ta film, tantalum nitride having a crystal structure close to that of Ta α-phase is formed on a Ta underlayer with a thickness of about 10 to 50 nm to form an α-phase Ta film. It can be easily obtained.

When the W film is formed, it is formed by a sputtering method with W as a 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]. The W film can be made low in resistivity by enlarging the crystal grains, but when a large amount of an impurity element such as oxygen is contained in W, crystallization is hindered and the resistance becomes high. From this fact, in the case of the sputtering method, a W target having a purity of 99.9999 [%] is used, and the W film is formed with sufficient consideration so that impurities are not mixed from the vapor phase during film formation. Resistivity 9-20
[μΩcm] can be realized.

In this embodiment, the first conductive film 500 is used.
Although 8 is Ta and the second conductive film 5009 is W, it is not particularly limited, and any of Ta, W, Ti, Mo, Al and Cu is used.
It may be formed of an element selected from the above, or an alloy material or a compound material containing the above element as a main component. Also,
A semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. As a preferable example of another combination other than this embodiment, a combination in which the first conductive film 5008 is formed of tantalum nitride (TaN) and the second conductive film 5009 is W, and the first conductive film 5008 is used. Are formed of tantalum nitride (TaN), the second conductive film 5009 is made of Al, the first conductive film 5008 is made of tantalum nitride (TaN), and the second conductive film 5009 is made of Cu. Can be mentioned.

Next, a mask 5010 made of resist is formed, and a first etching process for forming electrodes and wirings is performed. In this embodiment, ICP (Inductively Couple)
d Plasma: Inductively coupled plasma) etching method,
CF ₄ and Cl ₂ are mixed in the etching gas, and RF of 500 [W] (13.56 [MH] is applied to the coil type electrode at a pressure of 1 [Pa].
z]) Applying electric power to generate plasma. RF of 100 [W] (13.56 [MH] also on the substrate side (sample stage)
z]) Apply power and apply a substantially negative self-bias voltage. When CF ₄ and Cl ₂ are mixed, W film and Ta
The film is etched to the same extent.

Under the above etching conditions, the shape of the mask made of a resist is made appropriate, and the end portions of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. Become. The angle of the taper portion is 15 to 45 °. In order to perform etching without leaving a residue on the gate insulating film, it is advisable to increase the etching time at a rate of about 10 to 20%. Since the selection ratio of the silicon oxynitride film to the W film is 2 to 4 (typically 3), the surface where the silicon oxynitride film is exposed should be etched by about 20 to 50 nm by the overetching process. become. Thus, the first etching process is performed to form the first conductive layer and the second conductive layer.
Shaped conductive layers 5011 to 5016 (first conductive layer 50
11a to 5016a and second conductive layers 5011b to 501
6b) is formed. At this time, in the gate insulating film 5007, a region which is not covered with the first shape conductive layers 5011 to 5016 is etched to be thinned by about 20 to 50 nm. (Fig. 9 (B))

Then, a first doping process is performed to add an impurity element imparting N-type conductivity. The doping method may be an ion doping method or an ion implantation method. The condition of the ion doping method is that the dose amount is 1 × 10 ^{13 to} 5 × 10 5.
¹⁴ [atoms / cm ² ] and the acceleration voltage is 60 to 100 [keV]. An element belonging to Group 15 is used as an impurity element imparting N-type, typically phosphorus (P) or arsenic (As), but phosphorus (P) is used here. In this case, the conductive layers 5011 to 5015 serve as masks for the impurity element imparting N-type conductivity, and the first impurity regions 50 are self-aligned.
17-5025 are formed. First impurity region 501
7 to 5025 is 1 × 10 ²⁰ to 1 × 10 ²¹ [atoms / cm ³ ].
An impurity element imparting N-type conductivity is added within the concentration range of.
(Fig. 9 (B))

Next, as shown in FIG. 9C, a second etching process is performed without removing the resist mask. CF ₄ , Cl _2, and O ₂ are used as etching gas, and W
The film is selectively etched. At this time, the second shape conductive layers 5026 to 5031 are formed by the second etching treatment.
(First conductive layers 5026a to 5031a and second conductive layers 5026b to 5031b) are formed. At this time, in the gate insulating film 5007, the second shape conductive layer 50 is formed.
The area not covered by 26-5031 is 20-50 [n
A region thinned by etching about [m] is formed.

The etching reaction of the W film or the Ta film with the mixed gas of CF ₄ and Cl ₂ can be estimated from the radical or ion species generated and the vapor pressure of the reaction product.
Comparing the vapor pressures of fluoride and chloride of W and Ta,
WF ₆ which is a fluoride of
l ₅ , TaF ₅ , and TaCl ₅ are in the same level. Therefore, C
Both the W film and the Ta film are etched by the mixed gas of F ₄ and Cl ₂ . However, when an appropriate amount of O ₂ is added to this mixed gas, CF ₄ and O ₂ react to form CO and F, and a large amount of F radicals or F ions are generated. As a result, the etching rate of the W film having a high fluoride vapor pressure is increased. On the other hand, Ta has a relatively small increase in etching rate even if F increases. Moreover, since Ta is more easily oxidized than W, the surface of Ta is oxidized by adding O ₂ .
Since Ta oxide does not react with fluorine or chlorine,
The etching rate of the a film decreases. Therefore, W film and Ta
It becomes possible to make a difference in the etching rate from the film, and the etching rate of the W film can be made higher than that of the Ta film.

Then, a second doping process is performed as shown in FIG. In this case, the dose amount is made lower than that in the first doping process, and N is set as a condition for a high acceleration voltage.
Doping with an impurity element that imparts a mold. For example, the acceleration voltage is 70 to 120 [keV] and 1 × 10 ¹³ [atoms / cm
² ], and a new impurity region is formed inside the first impurity region formed in the island-shaped semiconductor layer in FIG. 9B. The doping is performed in the second shape conductive layer 5026 to
5030 is used as a mask for impurity elements,
The regions below the conductive layers 5026a to 5030a are also doped with the impurity element. Thus
Third impurity regions 5032 to 5036 are formed. The concentration of phosphorus (P) added to the third impurity regions 5032 to 5036 is the first conductive layers 5026a to 5030.
It has a gradual concentration gradient according to the film thickness of the taper portion of a. Note that in the semiconductor layer which overlaps with the tapered portions of the first conductive layers 5026a to 5030a, the first conductive layer 5
Although the impurity concentrations are slightly lowered from the ends of the tapered portions of 026a to 5030a toward the inside, the concentrations are almost the same.

A third etching process is performed as shown in FIG. CHF ₆ is used as an etching gas and a reactive ion etching method (RIE method) is used. Third
Of the first conductive layers 5026a to 526a-5
The taper part of 031a is partially etched to
The area in which the conductive layer of the first layer overlaps the semiconductor layer is reduced. The third shape conductive layer 5037 is formed by the third etching treatment.
5042 (first conductive layers 5037a to 5042a and second conductive layers 5037b to 5042b) are formed. At this time, in the gate insulating film 5007, the area which is not covered with the third shape conductive layers 5037 to 5042 is further increased by 2.
A thinned region is formed by etching about 0 to 50 [nm].

By the third etching process, in the third impurity regions 5032 to 5036, the third impurity region 50 overlapping the first conductive layers 5037a to 5041a.
32a to 5036a and second impurity regions 5032b to 5036 between the first impurity region and the third impurity region.
b are formed.

Then, as shown in FIG.
Firstly, the island-shaped semiconductor layer 5004 forming the channel type TFT is formed.
From the fourth impurity region 5043 having a conductivity type opposite to that of
Forming 5048. The third shape conductive layer 5038b
It is used as a mask against impurity elements, and it is
Form a pure area. At this time, the N-channel type TFT
The island-shaped semiconductor layers 5003, 5005, 5006 to be formed and
And the wiring portion 5042 is entirely covered with a resist mask 5200.
Cover. The impurity regions 5043 to 5048 have this
Phosphorus was added at different concentrations, but diborane
(B₂H₆) Is used for the ion-doping method.
Even in these regions, the impurity concentration is 2 × 10 ²⁰~ 2 x 10
^{twenty one}[atoms / cm³]

Impurity regions are formed in the respective island-shaped semiconductor layers by the above steps. Third overlapping with island-shaped semiconductor layer
The conductive layers 5037 to 5041 in the shape of function as gate electrodes. Further, 5042 functions as an island-shaped source signal line.

After removing the resist mask 5200, a step of activating the impurity element added to each island-shaped semiconductor layer is performed for the purpose of controlling the conductivity type. This step is performed by a thermal annealing method using a furnace annealing furnace.
Besides, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. In the thermal annealing method, the oxygen concentration is 400 ppm to 700 in a nitrogen atmosphere having an oxygen concentration of 1 [ppm] or less, preferably 0.1 [ppm] or less.
The heat treatment is performed at [° C.], typically 500 to 600 [° C.], and in this embodiment, heat treatment is performed at 500 [° C.] for 4 hours.
However, when the wiring material used for the third shape conductive layers 5037 to 5042 is weak to heat, activation is performed after forming an interlayer insulating film (mainly containing silicon) to protect the wiring and the like. It is preferable to carry out.

Further, a step of hydrogenating the island-shaped semiconductor layer is performed by performing heat treatment at 300 to 450 [° C.] for 1 to 12 hours in an atmosphere containing 3 to 100 [%] of hydrogen. This step is a step of terminating the dangling bond of the semiconductor layer by thermally excited hydrogen. Plasma hydrogenation (using hydrogen excited by plasma) may be performed as another means of hydrogenation.

Then, as shown in FIG. 11A, the first
The interlayer insulating film 5055 of 100 is formed from a silicon oxynitride film.
It is formed with a thickness of about 200 [nm]. After forming a second interlayer insulating film 5056 made of an organic insulating material thereon, a first interlayer insulating film 5055, a second interlayer insulating film 5056,
A contact hole is formed in the gate insulating film 5007 and each wiring (including a connection wiring and a signal line) 5057.
After patterning 5062 and 5064, a pixel electrode 5063 that contacts the connection wiring 5062 is patterned.

As the second interlayer insulating film 5056, a film made of an organic resin can be used, and as the organic resin, polyimide, polyamide, acrylic, BCB (benzocyclobutene) or the like can be used. In particular, since the second interlayer insulating film 5056 has a strong implication of flattening, acrylic having excellent flatness is preferable. In this embodiment, the acrylic film is formed with a film thickness that can sufficiently flatten the step formed by the TFT. The thickness is preferably 1 to 5 [μm] (more preferably 2 to 4 [μm]).

The contact holes are formed by dry etching or wet etching, and N type impurity regions 5017, 5018, 5021, 5023 to 5025 are formed.
Alternatively, a contact hole reaching the P-type impurity regions 5043 to 5048, a contact hole reaching the wiring 5042, a contact hole (not shown) reaching the power supply line, and a contact hole (not shown) reaching the gate electrode are formed, respectively. .

Wiring (including connection wiring and signal line) 5
057-5062, 5064, Ti film 100 [n
m], 300 [nm] aluminum film containing Ti, Ti film 1
A laminated film having a three-layer structure in which 50 [nm] is continuously formed by a sputtering method is patterned into a desired shape is used. Of course,
Other conductive films may be used.

In addition, in this embodiment, a MgAg film is formed as the pixel electrode 5063 to a thickness of 110 nm, and patterning is performed. Contact is made by disposing the pixel electrode 5063 so as to be in contact with and overlap with the connection wiring 5062. This pixel electrode 5063 serves as the cathode of the OLED element. (Figure 11 (A))

Next, as shown in FIG. 11B, an insulating film containing silicon (a silicon oxide film in this embodiment) is formed to a thickness of 500 [nm] and is formed at a position corresponding to the pixel electrode 5063. An opening is formed and a third interlayer insulating film 5065 which functions as a bank is formed. By using a wet etching method when forming the opening, 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 OLED layer due to the step difference becomes a significant problem, so caution is required.

Next, the OLED layer 5066 and the anode (counter electrode) 5067 are continuously formed by using a vacuum evaporation method without exposing to the atmosphere. The thickness of the OLED layer 5066 is 80 to 200 [nm] (typically 100 to 120 [nm]),
The anode 5067 was formed of an ITO film.

In this step, the OLED layer and the anode are sequentially formed on the pixel corresponding to red, the pixel corresponding to green and the pixel corresponding to blue. However, OLED
The layers have poor resistance to solutions and must be formed individually for each color without the use of photolithographic techniques. Therefore, it is preferable to hide a portion other than a desired pixel by using a metal mask and selectively form the OLED layer and the anode only at necessary portions.

That is, first, a mask for hiding all but the pixels corresponding to red is set, and the OLED layer emitting red light is selectively formed using the mask. Next, a mask that hides all pixels other than the pixels corresponding to green is set, and the OLED layer emitting green light is selectively formed using the mask. Next, similarly, a mask that hides all pixels other than the pixel corresponding to blue is set, and the OLED layer emitting blue light is selectively formed using the mask. Note that although different masks are used here, the same mask may be used again.

Here, three kinds of OLEs corresponding to RGB are used.
Although the method of forming D element was used, white light emitting OLED
A method in which an element and a color filter are combined, a method in which an OLED element emitting blue or blue-green light and a phosphor (fluorescent color conversion layer: CCM) are combined, and a cathode (pixel electrode)
Alternatively, a method of stacking OLED elements corresponding to RGB by utilizing transparent electrodes may be used.

A known material can be used for the OLED layer 5066. As a known material, it is preferable to use an organic material in consideration of driving voltage. For example, a four-layer structure including a hole injection layer, a hole transport layer, a light emitting layer, and an electron injection layer may be used as the OLED layer.

Next, an anode 5067 is formed using a metal mask on a pixel (a pixel on the same line) having a switching TFT whose gate electrode is connected to the same gate signal line.

In this embodiment, the anode 5067 is I
Although TO was used and MgAg was used as the cathode 5063,
The present invention is not limited to this. Anode 5067 and cathode 5
Other known materials may be used as 063.

Finally, a passivation film 5068 made of a silicon nitride film is formed to a thickness of 300 [nm]. By forming the passivation film 5068, the OLED layer 5066 can be protected from moisture and the like, and the reliability of the OLED element can be further improved.

Thus, the OLED display device having the structure shown in FIG. 11B is completed. In the manufacturing process of the OLED display device of this embodiment, the source signal line is formed of Ta and W, which are the materials forming the gate electrode, and the source and drain electrodes are formed because of the circuit configuration and the process. Although the gate signal line is formed of Al that is the wiring material that is formed, a different material may be used.

Although the TFT in the active matrix OLED display device manufactured by the above process has a top gate structure, it has a bottom gate structure.
The present embodiment can be easily applied to FT and TFTs having other structures.

Further, although the glass substrate is used in the present embodiment, the present invention is not limited to the glass substrate, and the present invention can be carried out by using a plastic substrate, a stainless steel substrate, a single crystal wafer or the like other than the glass substrate. It is possible.

By the way, the OLED display device of this embodiment has a TF structure having an optimum structure not only for the pixel portion but also for the driving circuit portion.
By arranging T, it is possible to exhibit extremely high reliability and improve operating characteristics. It is also possible to add a metal catalyst such as Ni in the crystallization step to enhance the crystallinity.
Thereby, the drive frequency of the source signal line drive circuit is set to 1
It is possible to set it to 0 [MHz] or higher.

First, a TFT having a structure in which hot carrier injection is reduced so as not to decrease the operation speed as much as possible,
N-channel TF of CMOS circuit forming drive circuit section
Used as T.

In the case of this embodiment, the N-channel TFT active
The insulating layer is formed between the source region, drain region, and gate insulating film.
Overlap LDD region that overlaps with the gate electrode
(L _OVRegion) and the gate electrode with the gate insulating film sandwiched between
Offset LDD area (L_OFFArea) and
Including a channel formation region.

Also, a P channel type TFT of a CMOS circuit
Since the deterioration due to hot carrier injection is hardly noticeable, it is not necessary to particularly provide the LDD region. Of course, it is possible to provide an LDD region as in the N-channel TFT and take measures against hot carriers.

In addition, when a CMOS circuit in which a current flows bidirectionally in the channel forming region, that is, a CMOS circuit in which the roles of the source region and the drain region are exchanged is used in the driving circuit, the N circuit forming the CMOS circuit is formed. In the channel type TFT, it is preferable to form LDD regions on both sides of the channel formation region with the channel formation region sandwiched therebetween. Further, in the case where a CMOS circuit that needs to suppress off current as low as possible is used in the driver circuit, the N-channel TFT forming the CMOS circuit is
It preferably has an _OV region.

When the state shown in FIG. 11 (B) is completed, a protective film (laminate film, ultraviolet curable 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 OLED 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: FPC) for connecting a terminal routed from an element or a circuit formed on a substrate to an external signal terminal. Is attached to complete the product.

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

In the manufacturing process of the display device described above, the N-type TFT is removed by omitting the forming process of the P-type TFT.
The present invention can be applied to a manufacturing process of a display device using a unipolar TFT, which is configured by only.

The manufacturing process is not limited to this.
The structure of the TFT constituting the display device is not limited to the top gate type, and may be the bottom gate type or the dual gate type. Further, the present embodiment is applicable not only to the display device using the OLED element but also to the display device using other light emitting elements.

Example 4 In this example, the OLE of the present invention is used.
An example of manufacturing a D display device will be described with reference to FIGS.

FIG. 12A is a top view of the OLED display device, FIG. 12B is a sectional view taken along the line AA ′ in FIG. 12A, and FIG. 12C is FIG. ) BB '
FIG.

Pixel portion 400 provided on substrate 4001
2, source signal line driver circuit 4003, first and second
A sealing material 4009 is provided so as to surround the gate signal line driver circuits 4004a and 4004b. Further, a sealing material 4008 is provided over the pixel portion 4002, the source signal line driver circuit 4003, and the first and second gate signal line driver circuits 4004a and 4004b. Therefore, the pixel portion 4002, the source signal line driver circuit 4003, and the first and second gate signal line driver circuits 4004a and 4004b include the substrate 4001, the sealant 4009, and the sealant 4008.
And are sealed with a filling material 4210.

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 include a plurality of TFTs. In FIG. 12B, typically, the source signal line driver circuit 4 formed over the base film 4010.
Drive TFT included in 003 (however, N-channel type TFT and P-channel type TFT are shown here) 4201
A pixel TFT (TFT for inputting a drain current to the OLED element) 4202 included in the pixel portion 4002 is illustrated.

In this embodiment, a P-channel type TFT and an N-channel type TFT manufactured by a known method are used as the driving TFT 4201, and a P-channel type TFT manufactured by a known method is used as the TFT 4202.

An interlayer insulating film (planarizing film) 4301 is formed on the driving TFT 4201 and the TFT 4202, and a pixel electrode (anode) 4203 electrically connected to the drain region of the TFT 4202 is formed thereon. Pixel electrode 42
As 03, a transparent conductive film having a large work function is used. 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. An OLED layer 4204 is formed on the pixel electrode 4203 in this opening. A known organic material or inorganic material can be used for the OLED layer 4204. Further, the organic material includes a low molecular weight (monomer type) material and a high molecular weight (polymer type) material, but either may be used.

As a method of forming the OLED layer 4204, a known vapor deposition technique or coating technique may be used. Also, OL
The structure of the ED layer may be a laminated structure or a single layer structure by freely combining a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer or an 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 provided on the OLED layer 4204. It is formed. Also, the cathode 4
It is desirable to remove water and oxygen existing at the interface between 205 and the OLED layer 4204 as much as possible. Therefore, OLE
It is necessary to devise that the D layer 4204 is formed in a nitrogen or rare gas atmosphere and the cathode 4205 is formed without being exposed to oxygen or moisture. In the present embodiment, the above-described film formation is possible by using a multi-chamber type (cluster tool type) film forming apparatus. And the cathode 4205
Is applied with a predetermined voltage.

As described above, the pixel electrode (anode) 42
03, an OLED layer 4204 and a cathode 4205
The LED element 4303 is formed. Then, the protective film 42 is formed on the insulating film 4302 so as to cover the OLED element 4303.
09 are formed. The protective film 4209 is effective in preventing oxygen, moisture, and the like from entering the OLED element 4303.

Reference numeral 4005a is a lead wiring connected to the power supply line, and is electrically connected to the source region of the TFT 4201. The lead wiring 4005a passes between the sealing material 4009 and the substrate 4001 and is electrically connected to the FPC wiring 4333 included in the FPC 4006 through the anisotropic conductive film 4300.

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
(Fiberglass-Reinforced Pl
astics) plate, PVF (polyvinyl fluoride)
A film, mylar film, polyester film or 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 emission direction of light from the OLED element is toward the cover material side, the cover material must be transparent. In that case, glass plate, plastic plate,
A transparent material such as polyester film or acrylic film is used.

Further, as the filler 4210, 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 E
VA (ethylene vinyl acetate) can be used. In this example, nitrogen was used as the filler.

In order to expose the filler 4210 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 OLED element 4303 can be suppressed.

As shown in FIG. 12C, the pixel electrode 42
At the same time that 03 is formed, 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 the PC 4006, the conductive film 4203a on the substrate 4001 and the FPC wiring 4333 on the FPC 4006 are electrically connected by the conductive filler 4300a. Further, the present embodiment is applicable not only to the display device using the OLED element but also to the display device using other light emitting elements.

[Embodiment 5] FIG. 13 is a sectional view showing the structure of a pixel of an OLED display device of the present invention. In addition, in the present embodiment, as an element constituting a pixel of the OLED display device,
T for flowing a drain current through the OLED element and the OLED element
Only FT is shown.

In FIG. 13A, the pixel substrate 1600
A TFT 1601 is formed on the top. TFT 160
1 denotes a channel formation in which a first gate electrode 1603a, a second gate electrode 1603b, and an insulating film 1602 and an insulating film 1605 are sandwiched between the first gate electrode and the second gate electrode. A dual-gate TFT having a region 1604b. One of the source region and the drain region of the TFT 1601 is 1604a and the other is 1604a.
604c. After the TFT 1601 is formed, the interlayer film 1606 is formed.

Note that the TFT 1601 is not limited to the structure shown in the figure, and a TFT having a known structure can be used freely.

Next, a transparent conductive film typified by ITO or the like is formed, patterned into a desired shape, and the pixel electrode 16 is formed.
08 is formed. Here, the pixel electrode 1608 is an anode. In the interlayer film 1606, contact holes reaching the source region and the drain region of the TFT 1601, 1604a and 1604c are formed, and a laminated film of Ti and Al containing Ti and Ti is formed and patterned into a desired shape to form wiring. 1607 and the wiring 1609 are formed. The wiring 1609 is brought into contact with the pixel electrode 1608 to be electrically connected.

Subsequently, an insulating film made of an organic resin material such as acrylic is formed, and the pixel electrode 1 of the OLED element 1614 is formed.
An opening is formed at a position corresponding to 608 to form an insulating film 161.
Form 0. Here, in order to avoid problems such as deterioration of the OLED layer and step breakage due to steps on the side wall of the opening, the opening is formed to have a sufficiently gentle tapered side wall.

Next, after forming the OLED layer 1611,
The counter electrode (cathode) 1612 of the OLED element 1614 is
It is formed by a laminated film in which a cesium (Cs) film having a thickness of 2 [nm] or less and a silver (Ag) film having a thickness of 10 [nm] or less are sequentially formed. By making the counter electrode 1612 of the OLED element 1614 extremely thin, the light generated in the OLED layer 1611 passes through the counter electrode 1612 and the pixel substrate 16
The light is emitted in the direction opposite to 00. Next, a protective film 1613 is formed for the purpose of protecting the OLED element 1614.

As described above, in the case of a display device that emits light in the direction opposite to that of the pixel substrate 1600, the OLED element 161 is used.
4, the TFT formed on the pixel substrate 1600 side
OLED element 1 through elements including 1601
Since it is not necessary to visually check the light emission of 614, the aperture ratio can be increased.

As a material of the pixel electrode 1608, T
iN or the like is used, the pixel electrode is used as a cathode, and the counter electrode 1612 is used.
Is formed using a transparent conductive film typified by ITO or the like to serve as an anode. In this way, the light emitted from the OLED layer 1611 may be emitted from the anode side in the opposite direction to the pixel substrate 1600.

FIG. 13B is a sectional view showing the structure of a pixel having an OLED element having a structure different from that of FIG. 13A.

In FIG. 13B, the same parts as those in FIG. 13A will be described using the same reference numerals.

13B, the TFT 1601 is formed and the interlayer film 1606 is formed until the TFT 1601 is formed.
It can be created in the same manner as the configuration shown in (A).

Next, the TFT 1601 is formed on the interlayer film 1606.
Source and drain regions, 1604a, 1604
A contact hole reaching c is formed. Then T
forming a laminated film of Al and Ti including i and Ti,
Then, a transparent conductive film typified by ITO or the like is formed.
Ti, a laminated film made of Al containing Ti and Ti, and IT
A transparent conductive film typified by O or the like is patterned into a desired shape to form a wiring 1621 composed of 1607 and 1608b, a wiring 1619, and a pixel electrode 1620.
To form. The pixel electrode 1620 is the OLED element 1624.
Corresponding to the anode of.

Subsequently, an insulating film made of an organic resin material such as acrylic is formed, and the pixel electrode 1 of the OLED element 1624 is formed.
An opening is formed at a position corresponding to 620 to form the insulating film 161.
Form 0. Here, in order to avoid problems such as deterioration of the OLED layer and step breakage due to steps on the side wall of the opening, the opening is formed to have a sufficiently gentle tapered side wall.

Next, after forming the OLED layer 1611,
The counter electrode (cathode) 1612 of the OLED element 1624 is
It is formed by a laminated film in which a cesium (Cs) film having a thickness of 2 [nm] or less and a silver (Ag) film having a thickness of 10 [nm] or less are sequentially formed. By making the film thickness of the counter electrode 1612 of the OLED element 1624 extremely thin, the light generated in the OLED layer 1611 passes through the counter electrode 1612 and the pixel substrate 16
The light is emitted in the direction opposite to 00. Next, a protective film 1613 is formed for the purpose of protecting the OLED element 1624.

As described above, in the case of a display device that emits light in the direction opposite to that of the pixel substrate 1600, the OLED element 162 is used.
4, the TFT formed on the pixel substrate 1600 side
OLED element 1 through elements including 1601
Since it is not necessary to visually check the light emission of 624, the aperture ratio can be increased.

It should be noted that the pixel electrode 1620 and the wiring 1621.
TiN or the like is used as the material of
The counter electrode 1612 is formed using a transparent conductive film typified by ITO or the like to serve as an anode. In this way, light emitted from the OLED layer 1611 may be emitted from the anode side in a direction opposite to that of the pixel substrate 1600.

In this case, it is necessary for the TFT of the pixel of the display device of the present invention to pass a current through the OLED element to be of N type.

The pixel having the structure shown in FIG.
As compared with the pixel having the structure shown in FIG. 3A, a wiring 1619 connected to the source region or the drain region of the TFT
Since the pixel electrode 1620 can be patterned using a common photomask, the number of photomasks required in the manufacturing process can be reduced and the process can be simplified. Further, the present embodiment is applicable not only to the display device using the OLED element but also to the display device using other light emitting elements.

[Example 6] In the present invention, by using an organic light emitting material that can utilize 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 is 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.

[0165]

[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.

[0168]

[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.

[0171]

[Chemical 3]

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

[Embodiment 7] Since a display device using a light emitting element such as an OLED 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 an example of electronic equipment to which the present invention is applicable,
Video cameras, digital cameras, goggle-type displays (head-mounted displays), navigation systems, sound reproduction devices (car audio, audio components, etc.), notebook personal computers, game devices, personal digital assistants (mobile computers, mobile phones,
An image reproducing device provided with a recording medium such as a portable game machine or an electronic book (specifically, Digital Versatile Disc (DV)
D) and other recording media, and a device equipped with a display capable of displaying the image). In particular, for a portable information terminal that often sees the screen from an oblique direction, since a wide viewing angle is important, it is preferable to use a light emitting device. Specific examples of those electronic devices are shown in FIGS.

FIG. 14A shows a display device, which includes a housing 3001, a supporting base 3002, a display portion 3003, a speaker portion 3004, a video input terminal 3005, and the like. The present invention can be used in 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. The display device includes all display devices for personal computers, TV broadcast reception, advertisement display, and the like.

FIG. 14B shows a digital still camera including a main body 3101, a display section 3102, an image receiving section 3103, and
An operation key 3104, an external connection port 3105, a shutter 3106 and the like are included. The present invention can be used in the display portion 3102.

FIG. 14C shows a laptop personal computer, which has a main body 3201, a housing 3202, and a display section 32.
03, keyboard 3204, external connection port 3205,
A pointing mouse 3206 and the like are included. The present invention can be used in the display portion 3203.

FIG. 14D 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 present invention can be used in the display portion 3302.

FIG. 14 (E) shows a portable image reproducing device (specifically, a DVD reproducing device) equipped 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 present invention can be used in these display portions A, B 3403 and 3404. Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 14F shows a goggle type display (head mount display), which includes a main body 3501, a display portion 3502, and an arm portion 3503. The present invention can be used in the display portion 3502.

FIG. 14G 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, and the like. The present invention can be used in the display portion 3602.

FIG. 14H 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 present invention can be used in the display portion 3703. The display unit 3
703 displays white characters on a black background, so that the current consumption of the mobile phone can be suppressed.

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 image information with a lens or the like and use it for a front-type or rear-type projector.

[0184] Further, the above electronic devices are the Internet and 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 as small 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. Further, the electronic apparatus of this embodiment may use the light emitting device having any of the configurations shown in Embodiments 1 to 6. Further, the present embodiment is applicable not only to the display device using the OLED element but also to the display device using other light emitting elements.

[0187]

As described above, according to the present invention, the power supply circuit for supplying the current or voltage to the OLED element is built in the substrate of the display device, thereby reducing the number of parts of the display device, the mounting area, and the power consumption. Can be reduced. Further, the present invention can be applied not only to a display device using an OLED element but also to a display device using another light emitting element, and the above effects can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a display device of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional display device.

FIG. 3 is a diagram showing a circuit configuration of a pixel of a conventional display device.

FIG. 4 is a diagram showing a timing chart showing a driving method of a pixel of a conventional display device.

FIG. 5 is a diagram showing a timing chart showing a pixel driving method of a conventional display device.

FIG. 6 is a diagram showing a power supply circuit incorporated in the display device of the present invention.

FIG. 7 shows a power supply circuit incorporated in a display device of the present invention.

FIG. 8 is a block diagram showing a configuration of a display device of the present invention.

9A to 9C are diagrams showing manufacturing steps of a display device of the present invention.

FIG. 10 is a diagram showing a manufacturing process of a display device of the present invention.

FIG. 11 is a diagram showing a manufacturing process of a display device of the present invention.

12A and 12B are a top view and a cross-sectional view illustrating an appearance of a display device of the present invention.

FIG. 13 is a cross-sectional view showing a structure of a pixel of a display device of the present invention.

FIG. 14 illustrates examples of electronic devices to which the present invention can be applied.

Claims (20)

[Claims] 1. A display device in which a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have OLED elements.
A display device characterized in that a power supply circuit for applying current or voltage to an LED element to emit light is formed on a substrate. 2. A display device having a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines arranged in a matrix on a substrate, wherein the pixels have red, green, and blue OLED elements. OL for each of green, green and blue
A display device characterized in that a power supply circuit for applying current or voltage to an ED element to emit light is formed on a substrate. 3. A display device in which a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have OLED elements.
A display device characterized in that a power supply circuit for applying current or voltage to an LED element to emit light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. 4. A display device having a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines arranged in a matrix on a substrate, wherein the pixels have red, green, and blue OLED elements. OL for each of green, green and blue
A display device, wherein a power supply circuit for applying a current or a voltage to an ED element to emit light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. 5. The O according to claim 3 or 4,
The display device is characterized in that the LED element has a common cathode, and the output of the power supply circuit is composed of a source-grounded P-channel transistor. 6. The O according to claim 3 or 4,
A display device characterized in that the LED elements have a common anode, and the output of the power supply circuit is composed of a source grounded N-channel transistor. 7. The display device according to claim 5, wherein the difference between the maximum potential and the output potential in the power supply circuit is less than or equal to the threshold value of the P-channel transistor. 8. The display device according to claim 6, wherein the power supply circuit has a difference between a minimum potential and an output potential in the power supply circuit which is equal to or less than a threshold value of an N-channel transistor. 9. A display device in which a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have OLED elements that emit red, green and blue light. A display device, wherein a power supply circuit for supplying a current or a voltage to two of the OLED elements that emit red, green, and blue is formed on a substrate. 10. An electronic device using any one of claims 1 to 9. 11. A display device in which a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element, and a current or a voltage is applied to the light emitting element. A display device characterized in that a power supply circuit for emitting light is formed on a substrate. 12. A display device in which a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element that emits red, green, and blue light. A display device is characterized in that a power supply circuit for applying a current or a voltage to the light emitting elements for each of green and blue to emit light is formed on a substrate. 13. A display device having a plurality of pixels, a plurality of source signal lines and a plurality of gate signal lines arranged in a matrix on a substrate, wherein the pixels have a light emitting element, and apply current or voltage to the light emitting element. A display device, wherein a power supply circuit for emitting light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. 14. A display device in which a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines are arranged in a matrix on a substrate, and the pixels have a light emitting element that emits red, green, and blue light. A display device is characterized in that a power supply circuit for applying current or voltage to the light emitting elements for each of green and blue to emit light is formed on a substrate, and the power supply circuit is a power supply circuit using an operational amplifier. 15. The method according to claim 13 or 14,
The display device is characterized in that the light emitting element has a common cathode, and the output of the power supply circuit is composed of a source-grounded P-channel transistor. 16. The method according to claim 13 or 14,
The display device is characterized in that the light emitting element has a common anode, and the output of the power supply circuit is composed of a source grounded N-channel transistor. 17. The display device according to claim 15, wherein a difference between a maximum potential and an output potential in the power supply circuit is less than or equal to a threshold value of a P-channel type transistor in the power supply circuit. 18. The display device according to claim 16, wherein the power supply circuit has a difference between a minimum potential and an output potential in the power supply circuit which is equal to or less than a threshold value of an N-channel transistor. 19. A display device having a plurality of pixels, a plurality of source signal lines, and a plurality of gate signal lines arranged in a matrix on a substrate, wherein the pixels each have a light emitting element that emits red, green, and blue light. A display device, wherein a power supply circuit for supplying a current or a voltage to two of the light emitting elements that emit red, green, and blue is formed on a substrate. 20. Any one of claims 11 to 19
Electronic equipment using the term.