JP2001272968A - Display system and electric appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display system adjusting emission luminance of light emitting elements included in a light emitting device in accordance with sur rounding information. SOLUTION: In this system, a sensor 2011 detects surrounding information as an electric signal and a CPU 2013 converts the signal into a correction signal for correcting emission luminance of EL(electroluminescent) elements based on preliminarily set comparison data. When this correction signal is inputted to a voltage varying unit 2010, the unit 2010 applies a prescribed correction potential to the EL elements. Thus, emission luminance of the EL elements 2003 is controlled in this display system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display system and an electric appliance capable of adjusting brightness according to surrounding information.

[0002]

2. Description of the Related Art In recent years, an organic EL material EL (Electro Lum) has been developed.
display device using an EL element as a self-luminous element utilizing the phenomenon (including fluorescence and phosphorescence).
L display device) is being developed. The EL element referred to here is an OLED (Organic Light Emitting Light).
vice). Since the EL display device is a self-luminous type, it does not require a backlight like a liquid crystal display device and has a wide viewing angle, so that it is promising as a display portion of a portable device used outdoors.

There are two types of EL display devices, a passive type (simple matrix type) and an active type (active matrix type), and both are being actively developed. In particular, an active matrix type EL display device has attracted attention at present. In addition, organic materials to be light emitting layers of EL elements are classified into low-molecular (monomer) organic EL materials and high-molecular (polymer) organic EL materials, and both are being actively studied.

The EL element is an EL (Electro Luminescenc).
e: a layer containing an organic EL material from which luminescence generated by applying an electric field is obtained (hereinafter, referred to as an EL layer)
, An anode, and a cathode. Luminescence in an organic EL material includes light emission (fluorescence) when returning from a singlet excited state to a ground state and light emission (phosphorescence) when returning from a triplet excited state to a ground state. In the EL display device of the present invention, it is possible to use an EL element containing either organic EL material.

[0005]

In a conventional light emitting device such as an EL display device or a semiconductor diode, there is provided a function of adjusting the light emission luminance of a light emitting element included in the light emitting device according to information around the light emitting device. There is nothing.

Therefore, in the present invention, the light emitting device is an EL device.
Taking a display device as an example, a display system that enables brightness adjustment of the EL display device in correspondence with environmental information around the EL display device and biological information of a person who uses the EL display device is referred to as a display system. Provided is an appliance using a display system.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. Note that in the EL display device, the emission luminance of the EL element including the cathode, the EL layer, and the anode can be adjusted by the amount of current flowing through the EL element. However, the amount of current flowing through the EL element depends on the potential of the EL element. Control is possible by changing. Therefore, the present invention uses the following display system.

First, information around the EL display device is detected as an information signal by a light receiving element such as a photodiode, a CdS photoconductive element, and a sensor including a CCD (charge coupled device) and a CMOS sensor. Next, the sensor converts this information signal into an electric signal
(Central Processing Unit), this electric signal is converted by the CPU into a signal for controlling the potential applied to adjust the light emission luminance of the EL element. In addition,
In this specification, a signal converted and output by the CPU is called a correction signal. Further, by inputting the correction signal to the voltage variable device, the potential of the electrode of the EL element which is not connected to the TFT is controlled. Note that, in this specification, the potential controlled here is referred to as a correction potential.

By using the above display system, it is possible to provide an EL display, that is, an electric appliance that controls the amount of current flowing through the EL element and adjusts the luminance according to the surrounding information. In this specification, the surrounding information is
This refers to surrounding environmental information in the EL display device and biological information of a person who uses the EL display device. Furthermore, the surrounding environment information refers to information such as brightness (the amount of visible light or infrared light), temperature, and humidity.
It refers to information such as the degree of redness, pulse, blood pressure, body temperature, or degree of pupil opening of the user.

According to the present invention, in the case of a digital drive system,
By applying a correction potential according to the surrounding information by a voltage variable device connected to the EL element, a potential difference applied to the EL element can be controlled to obtain a desired luminance. On the other hand, in the case of the analog drive system, the voltage variable device connected to the EL element applies a correction potential according to the surrounding information to control the potential difference applied to the EL element. A desired luminance can be obtained by controlling the potential of the analog signal so as to obtain a high contrast. By performing these methods, the present invention can be implemented in either a digital system or an analog system. The sensor is
It may be formed integrally with the EL display device.

The current controlling TFT for controlling the amount of current flowing through the EL element allows a relatively large amount of current to flow to make the EL element emit light, compared to the switching TFT for controlling the driving of the current controlling TFT. Note that controlling the driving of a TFT means that the TFT is turned on or off by controlling a voltage applied to a gate electrode included in the TFT. In the present invention, when it is desired to display a low light emission luminance in accordance with surrounding information, a small amount of current flows through the current control TFT.

[0012]

FIG. 1 is a schematic diagram showing the configuration of an information-enabled EL display device according to the present invention. In this embodiment, a case where a digitally driven time-division gray scale method is used will be described. In FIG. 1, reference numeral 2001 denotes a TFT functioning as a switching element (hereinafter referred to as a switching TF).
T and 2002 are TFTs functioning as elements (current control elements) for controlling the current supplied to the EL element 2003
(Hereinafter, referred to as a current control TFT or an EL drive TFT), and 2004 is a capacitor (referred to as a storage capacitor or an auxiliary capacitor). The switching TFT 2001 is connected to a gate line 2005 and a source line (data line) 2006. The drain of the current controlling TFT 2002 is connected to the EL element 2003, and the source is connected to the power supply line 200.
7 is connected.

When the gate line 2005 is selected, the gate of the switching TFT 2001 is opened, and the source line 200 is opened.
6 is stored in the capacitor 2004, and the gate of the current controlling TFT 2002 is opened. After the gate of the switching TFT 2001 is closed, the electric charge stored in the capacitor 2004 causes the current controlling TFT 2001 to close.
The gate of 2002 remains open, during which time the EL element 2003 emits light. The amount of light emitted from the EL element 2003 changes depending on the amount of current flowing.

The amount of current flowing at this time is controlled by a potential applied to the power supply line (this is referred to as an EL drive potential in this specification) and a potential controlled by a correction signal input to the voltage variable device 2010 ( In this specification, this is controlled to a potential difference from the correction potential. In this embodiment, the EL drive potential is maintained at a constant potential. Further, the voltage variable device 2010 can change the voltage from the EL drive power supply 2009 to a positive or negative value, and thereby can control the correction potential.

In the digital drive gray scale display of the present invention, the gate of the current control TFT 2002 is opened or closed by a data signal input from the source line 2006. Note that in this specification, one electrode connected to a TFT of an EL element is called a pixel electrode, and the other electrode is called a counter electrode. When the switch 2015 is turned on, a correction potential controlled by the voltage variable device 2010 is applied to the counter electrode. Since the EL driving potential applied to the pixel electrode is constant, a current based on the correction potential flows through the EL element by controlling the correction potential, and the EL element 2003 can emit light with a desired luminance.

The correction potential applied by the voltage changer 2010 is determined as follows. First, sensor 2
011 detects surrounding information as an analog signal, and converts the obtained analog signal into a digital signal by the A / D converter 2012. This digital signal is transmitted to the CPU 201
3 is converted. The CPU 2013 converts the input signal into a correction signal for correcting the emission luminance of the EL element based on preset comparison data. The correction signal converted by the CPU 2013 is D
The signal is input to the / A converter 2014 and converted again into an analog correction signal. When the correction signal is input to the voltage variable device, the voltage variable device 2010 applies a predetermined correction potential.

As described above, the active matrix type E
Attach the sensor 2011 to the L display device,
011 based on the surrounding information signal detected
The greatest feature of the present invention is that the correction potential can be changed at 010 to adjust the emission luminance of the EL element. An EL display using this display system can adjust the light emission luminance of the EL display device according to surrounding information.

Next, FIG. 2 shows a schematic block diagram of an active matrix type EL display device used in the present invention. FIG.
The active matrix EL display device in FIG. 1A includes a pixel portion 101 formed by TFTs formed over a substrate, a data signal side driving circuit 102 and a gate signal side driving circuit 103 arranged around the pixel portion. . Further, a time-division grayscale data signal generating circuit 113 for forming a digital data signal input to the pixel portion is provided.

In the pixel section 101, a plurality of pixels 104 are arranged in a matrix. FIG. 2 is an enlarged view of the pixel 104.
It is shown in (B). The switching TFT 10 is included in the pixel.
5 and a current control TFT 108 are arranged. The source region of the switching TFT 105 is connected to a data wiring (source wiring) 107 for inputting a digital data signal.

Reference numeral 108 denotes a current controlling TFT.
The gate electrode is connected to the drain region of the switching TFT 105. Then, the current control TFT 108
Are connected to the power supply line 110, and the drain region is connected to the EL element 109. EL element 1
Reference numeral 09 denotes an anode (pixel electrode) connected to the current control TFT 108 and a cathode (opposite electrode) provided opposite the anode with the EL layer interposed therebetween. The cathode is connected to the voltage variable device 111. I have.

The switching TFT 105 has n
A channel TFT or a p-channel TFT may be used. In the present embodiment, the current controlling TFT 108
Is an n-channel TFT, the current control T
The drain of the FT 108 is connected to the cathode of the EL element 109, and the current controlling TFT 108 is a p-channel TFT.
In this case, it is preferable that the drain of the current controlling TFT 108 is connected to the anode of the EL element 109.
However, the current control TFT 108 is an n-channel TF
If T, the source of the current control TFT 108 is E
The current control TFT 10 connected to the anode of the L element 109
8 is a p-channel TFT, the current control TF
A structure in which the source of T108 is connected to the cathode of the EL element 109 may be employed.

Further, a resistor (not shown) may be provided between the drain region of the current control TFT 108 and the anode (pixel electrode) of the EL element 109. By providing the resistor, it is possible to control the amount of current supplied from the current control TFT to the EL element, thereby preventing the influence of the variation in the characteristics of the current control TFT. The structure of the resistor is not limited, as long as the resistor has a resistance value sufficiently larger than the ON resistance of the current control TFT 108.

The capacitor 112 includes a switching TF
It is provided to hold the gate voltage of the current control TFT 108 when T105 is in a non-selected state (off state). The capacitor 112 is a switching TF.
It is connected to the drain region of T105 and the power supply line 110.

Next, the data signal side driving circuit 102 basically has a shift register 102a, a latch 1 (102b), and a latch 2 (102c). A clock pulse (CK) and a start pulse (SP) are input to the shift register 102a, a digital data signal (Digital Data Signals) is input to the latch 1 (102b), and a latch signal is input to the latch 2 (102c). (Latch Signa
ls) is entered. Although only one data signal side driving circuit 102 is provided in FIG. 2A, two data signal side driving circuits may be provided in the present invention.

Further, the gate signal side driving circuit 103 has a shift register, a buffer and the like (neither is shown). Note that although two gate signal side driver circuits 103 are provided in FIG. 2A, one gate signal side driver circuit may be provided in the present invention.

The time division gray scale data signal generating circuit 113 (S
In a PC (Serial-to-Parallel Conversion Circuit), a video signal (a signal including image information) composed of an analog signal or a digital signal is converted into a digital data signal for performing a time-division gray scale, and a time-division gray scale is used. A timing pulse or the like necessary for display is generated and input to the pixel portion.

The time-division gradation data signal generation circuit 11
In No. 3, means for dividing one frame period into a plurality of sub-frame periods corresponding to n-bit (n is an integer of 2 or more) gradations, and an address period and a sustain period are selected in the plurality of sub-frame periods. The means and the sustain period are represented by Ts1: Ts2: Ts3: ...: Ts (n-
1): Ts (n) = 2 ⁰ : 2 ^-1 : 2 ^-2 : ...: 2- ^(n-2) : 2
^-(n-1) .

This time-division gradation data signal generating circuit 113
May be provided outside the EL display device of the present invention, or may be integrally formed. When provided outside the EL display device, the digital data signal formed there is input to the EL display device of the present invention. In that case,
The digital data signal thus formed is input to the EL display device of the present invention. In this case, the E of the present invention
An electric appliance having the L display device as a display includes the EL display device of the present invention and the time-division grayscale data signal generation circuit as separate components.

The time-division gradation data signal generation circuit 11
3 may be mounted on the EL display device of the present invention in the form of an IC chip or the like. In that case, a digital data signal formed by the IC chip is input to the EL display device of the present invention. In this case, an electric appliance having the EL display device of the present invention as a display includes the EL display device of the present invention mounted with an IC chip including a time-division grayscale data signal generation circuit as a component.

Finally, the time-division grayscale data signal generating circuit 113 is finally connected to the pixel section 101 and the data signal side driving circuit 1.
02 and the gate signal side drive circuit 103 can be formed using TFTs on the same substrate. In this case, if a video signal including image information is input to the EL display device, all the signals can be processed on the substrate. Needless to say, the time-division grayscale data signal generating circuit in this case is desirably formed by a TFT having a polysilicon film as an active layer used in the present invention. In this case, in the electric appliance having the EL display device of the present invention as a display, the time-division grayscale data signal generation circuit is built in the EL display device itself, so that the electric appliance can be downsized. .

Next, the time division gray scale display will be described with reference to FIGS. Here, a case where full color display of 2 ⁿ gradations is performed by an n-bit digital driving method will be described.

First, as shown in FIG. 3, one frame period is divided into n sub-frame periods (SF1 to SFn). Note that a period in which all the pixels in the pixel portion display one image is referred to as one frame period. In a normal EL display, the oscillation frequency is 60 Hz or more, that is, 60 or more frame periods are provided per second, and 60 or more images are displayed per second. When the number of images displayed per second becomes less than 60, flickering of the image such as flicker starts to be noticeable visually. Further, a period obtained by further dividing one frame period is referred to as a sub-frame period. As the number of gradations increases, the number of divisions in one frame period also increases, and the driving circuit must be driven at a high frequency.

One subframe period is divided into an address period (Ta) and a sustain period (Ts). The address period is a time required to input data to all pixels in one subframe period, and the sustain period (also called a lighting period) indicates a period during which the EL element emits light.

The n sub-frame periods (SF1 to SF)
n) address periods (Ta1 to Tan) respectively
Are all constant in length. The sustain periods (Ts) of SF1 to SFn are represented by Ts1 to Tsn, respectively.
And

The length of the sustain period is Ts1: Ts
2: Ts3:...: Ts (n-1): Tsn = 2 ⁰ :
2 ^-1 : 2 ^-2 : ...: 2- ^(n-2) : 2- ^(n-1) However, SF1 to SFn may appear in any order. The combination of this sustain period is 2
Desired gradation display can be performed among ⁿ gradations.

The potential difference between the correction potential and the EL drive potential is used to determine EL.
The amount of current flowing through the element is determined, and the emission luminance of the EL element is controlled. That is, in order to adjust the emission luminance of the EL element, the correction potential may be adjusted.

Here, the present embodiment will be described in detail. First, the power supply line 110 is maintained at a constant EL drive potential, inputs a gate signal to the gate wiring 106, and turns on all the switching TFTs 105 connected to the gate wiring 106.

After the switching TFT 105 is turned on or at the same time as the switching TFT 105 is turned on, a digital data signal having information “0” or “1” is input to the source region of the switching TFT 105.

The digital data signal is a switching TF
When input to the source region of T105, the current control TF
The digital data signal is input to and held in the capacitor 112 connected to the gate electrode of T108. A period until a digital data signal is input to all pixels is an address period.

When the address period ends, the switching TFT is turned off, and the digital data signal held in the capacitor 112 is output to the current control TFT 1.
08 is input to the gate electrode.

It is more desirable that the potential applied to the anode of the EL element be higher than the potential applied to the cathode.
In this embodiment, the anode is connected to a power supply line as a pixel electrode, and the cathode is connected to a voltage variable device. Therefore, it is desirable that the EL drive potential is higher than the correction potential.
Conversely, when the cathode is connected to a power supply line as a pixel electrode and the anode is connected to a voltage variable device, it is desirable that the EL drive potential is lower than the correction potential.

In the present invention, the correction potential is controlled through the voltage variable device based on the surrounding information signal detected by the sensor. For example, when environmental information relating to the brightness around the EL display device is detected by the photodiode, and the detected signal is converted into a correction signal for adjusting the emission luminance of the EL element by the CPU, the signal is converted to a voltage variable device. , A corresponding correction potential is applied, and the correction potential changes. As a result, the potential difference between the EL drive potential and the correction potential changes, and the light emission luminance of the EL element can be changed. In the present embodiment, when the digital data signal has information of “0”, the current control TFT 10
8 is turned off, and the EL drive potential applied to the power supply line 110 is not applied to the anode (pixel electrode) of the EL element 109.

Conversely, when the information has the information “1”, the current control TFT 108 is turned on, and the power supply line 1
EL driving potential applied to the EL element 109
Is applied to the anode (pixel electrode) of the pixel.

As a result, the EL element 109 of the pixel to which the digital data signal having the information “0” is applied does not emit light. Then, the EL element 109 included in the pixel to which the digital data signal having the information “1” is applied emits light. A period until the light emission ends is a sustain period.

The period in which the EL element emits light (the pixel is turned on) is any one of Ts1 to Tsn. Here, it is assumed that a predetermined pixel is turned on during a period of Tsn.

Next, the address period is entered again, and after the data signals are inputted to all the pixels, the sustain period is entered. At this time, any of the periods Ts1 to Ts (n-1) is the sustain period. Here, it is assumed that a predetermined pixel is turned on during a period of Ts (n-1).

Thereafter, the same operation is repeated for the remaining n-2 subframes, and Ts (n-2), Ts
(N-3)... It is assumed that Ts1 and a sustain period are set, and a predetermined pixel is turned on in each subframe.

When n sub-frame periods appear, one frame period has ended. At this time, after a digital data signal having information of “1” is applied to the pixel during a sustain period during which the pixel is lit, the length of the period during which the pixel is lit is integrated, thereby calculating the floor of the pixel. The tone is determined. For example, when n = 8, if the luminance when the pixel emits light in all sustain periods is 100%, when the pixel emits light in Ts1 and Ts2, 75% luminance can be expressed, and Ts3, Ts5, and Ts8. If is selected, 16% luminance can be expressed.

In the present invention, the switch 2015 shown in FIG. 1 is turned off during the address period and turned on during the sustain period.

Next, the active matrix type E of the present invention
FIG. 4 schematically shows a cross-sectional structure of the L display device.

In FIG. 4, reference numeral 11 denotes a substrate, and 12 denotes an insulating film serving as a base (hereinafter, referred to as a base film). As the substrate 11, a translucent substrate, typically, a glass substrate, a quartz substrate,
A glass ceramic substrate or a crystallized glass substrate can be used. However, it must withstand the maximum processing temperature during the manufacturing process.

The base film 12 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used. However, the base film 12 need not be provided on a quartz substrate. As the base film 12, an insulating film containing silicon (silicon) may be used. Note that, in this specification, the “insulating film containing silicon” refers specifically to silicon such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (SiOxNy: x and y are arbitrary integers). On the other hand, it refers to an insulating film containing oxygen or nitrogen at a predetermined ratio.

Reference numeral 201 denotes a switching TFT, and n
Although formed by a channel type TFT, the switching TFT may be a p-channel type. Reference numeral 202 denotes a current control TFT, and FIG.
02 shows a case formed of a p-channel TFT. In this case, the drain of the current controlling TFT is EL
Connected to the anode of the device.

However, in the present invention, it is not necessary to limit the switching TFT to an n-channel TFT and the current control TFT to a p-channel TFT, and vice versa. Can also be used.

The switching TFT 201 includes a source region 13, a drain region 14, LDD regions 15a to 15d,
High concentration impurity region 16 and channel forming regions 17a, 1
Active layer including 7b, gate insulating film 18, gate electrode 19
a, 19b, a first interlayer insulating film 20, a source line 21, and a drain line 22. Note that the gate insulating film 18 or the first interlayer insulating film 20 may be common to all TFTs on the substrate, or may be different depending on the circuit or element.

The switching TFT 2 shown in FIG.
Reference numeral 01 denotes a so-called double gate structure in which the gate electrodes 19a and 19b are electrically connected. Of course, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel forming regions connected in series) such as a triple gate structure may be used.

The multi-gate structure is extremely effective in reducing the off-state current. If the off-state current of the switching TFT is sufficiently reduced, the capacitance required for the capacitor 112 shown in FIG. Can be. That is, since the area occupied by the capacitor 112 can be reduced, the multi-gate structure is
9 is also effective in increasing the effective light emitting area.

Further, in the switching TFT 201, the LDD regions 15a to 15d
Are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing off-state current. The length (width) of the LDD regions 15a to 15d is 0.5 to 3.5 μm, typically 2.0 to 2.0 μm.
The thickness may be set to 5 μm.

It is more preferable to provide an offset region (a region made of a semiconductor layer having the same composition as the channel forming region and to which no gate voltage is applied) between the channel forming region and the LDD region from the viewpoint of reducing the off-state current. Also,
In the case of a multi-gate structure having two or more gate electrodes, an isolation region 16 provided between channel formation regions
(A region where the same impurity element is added at the same concentration as the source region or the drain region) is effective in reducing off-state current.

Next, the current controlling TFT 202 includes a source region 26, a drain region 27, a channel forming region 29,
Gate insulating film 18, gate electrode 30, first interlayer insulating film 2
0, a source line 31 and a drain line 32. The gate electrode 30 has a single gate structure, but may have a multi-gate structure.

As shown in FIG. 2B, the drain of the switching TFT is connected to the gate of the current controlling TFT. Specifically, the gate electrode 30 of the current control TFT 202 in FIG. 4 is connected to the drain region 14 and the drain wiring (also referred to as connection wiring) 22 of the switching TFT 201.
Are electrically connected via Also, the source wiring 3
1 is connected to the power supply line 110 of FIG.

Further, from the viewpoint of increasing the amount of current that can flow, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 202 is increased (preferably 50).
To 100 nm, more preferably 60 to 80 nm). Conversely, in the case of the switching TFT 201, from the viewpoint of reducing the off current, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40 n).
m) is also effective.

While the structure of the TFT provided in the pixel has been described above, a driving circuit is also formed at this time. FIG. 4 shows a CMO as a basic unit for forming a driving circuit.
The S circuit is shown.

In FIG. 4, a TFT having a structure for reducing hot carrier injection while keeping the operation speed as low as possible is replaced with an n-channel TFT 204 of a CMOS circuit.
Used as Note that the driving circuit here refers to the data signal driving circuit 102 and the gate signal driving circuit 103 illustrated in FIG. Of course, other logic circuits (such as a level shifter, an A / D converter, and a signal dividing circuit) can be formed.

The active layer of the n-channel type TFT 204 includes a source region 35, a drain region 36, an LDD region 37, and a channel forming region 38. The LDD region 37 overlaps the gate electrode 39 with the gate insulating film 18 interposed. In this specification, the LDD region 37 is also called a Lov region.

The reason why the LDD region 37 is formed only on the drain region side of the n-channel type TFT 204 is to avoid lowering the operation speed. Further, the n-channel TFT 204 does not need to care much about the off-current value, and it is better to give much importance to the operation speed. Therefore,
The LDD region 37 completely overlaps the gate electrode, and it is desirable to reduce the resistance component as much as possible. That is, it is better to eliminate the so-called offset.

Further, a p-channel type TFT of a CMOS circuit
In the case of 205, since the deterioration due to hot carrier injection is hardly noticed, it is not necessary to particularly provide an LDD region. Therefore, the active layer includes the source region 40, the drain region 41, and the channel forming region 42, and the gate insulating film 18
And a gate electrode 43 are provided. Of course, n-channel type T
It is also possible to provide an LDD region similarly to the FT 204 and take measures against hot carriers.

The n-channel TFT 204 and the p-channel TFT 205 are covered with the first interlayer insulating film 20, respectively, and the source wirings 44 and 45 are formed. Both are electrically connected by the drain wiring 46.

Next, reference numeral 47 denotes a first passivation film having a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used. This passivation film 47 has a role of protecting the formed TFT from alkali metals and moisture. The EL layer finally provided above the TFT contains an alkali metal such as sodium. That is, the first passivation film 47 also functions as a protective layer that prevents these alkali metals (mobile ions) from entering the TFT side.

Reference numeral 48 denotes a second interlayer insulating film, TF
It has a function as a flattening film for flattening a step formed by T. As the second interlayer insulating film 48, an organic resin film is preferable, and polyimide, polyamide, acrylic, B
It is preferable to use CB (benzocyclobutene) or the like. These organic resin films have an advantage that a good flat surface is easily formed and the relative dielectric constant is low. Since the EL layer is very sensitive to irregularities, it is desirable that the step due to the TFT is almost completely absorbed by the second interlayer insulating film. In order to reduce the parasitic capacitance formed between the gate wiring or data wiring and the cathode of the EL element, it is desirable to provide a thick material having a low relative dielectric constant. Therefore, the film thickness is preferably 0.5 to 5 μm (preferably 1.5 to 2.5 μm).

Reference numeral 49 denotes a pixel electrode (anode of an EL element) made of a transparent conductive film, and a contact hole (opening) is formed in the second interlayer insulating film 48 and the first passivation film 47.
After opening, the current control TF
It is formed so as to be connected to the drain wiring 32 of T202. When the pixel electrode 49 and the drain region 27 are not directly connected as shown in FIG. 4, it is possible to prevent the alkali metal of the EL layer from invading the active layer via the pixel electrode.

On the pixel electrode 49, a third interlayer insulating film 50 made of a silicon oxide film, a silicon nitride oxide film or an organic resin film is provided with a thickness of 0.3 to 1 μm. The third interlayer insulating film 50 has an opening formed on the pixel electrode 49 by etching, and the edge of the opening is etched so as to have a tapered shape. The angle of the taper is preferably 10 to 60 ° (preferably 30 to 50 °).

An EL layer 51 is provided on the third interlayer insulating film 50. Although the EL layer 51 is used in a single layer or a laminated structure, the luminous efficiency is better when used in a laminated structure. Generally, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer are formed in this order on a pixel electrode. A structure such as a hole transport layer / light emitting layer / electron transport layer / electron injection layer may be used. In the present invention, any known structure may be used, and the EL layer may be doped with a fluorescent dye or the like.

As the organic EL material, for example, the materials disclosed in the following US patents or publications can be used. U.S. Patent No. 4,356,429, U.S. Patent No. 4,539,507, U.S. Patent No. 4,720,43
No. 2, U.S. Pat. No. 4,769,292; U.S. Pat. No. 4,885,211; U.S. Pat. No. 4,950,9
No. 50, U.S. Pat. No. 5,059,861, U.S. Pat. No. 5,047,687, U.S. Pat.
No. 446, U.S. Pat. No. 5,059,862, U.S. Pat. No. 5,061,617, U.S. Pat.
No. 1,629, U.S. Pat. No. 5,294,869, U.S. Pat. No. 5,294,870, JP-A-10-1895
No. 25, JP-A-8-241048 and JP-A-8-78159.

The EL display device can be roughly divided into four color display methods, R (red), G (green), B (blue).
A method of forming three kinds of EL elements corresponding to the above, a method of combining a white light emitting EL element and a color filter, and a combination of a blue or blue-green light emitting EL element and a phosphor (fluorescent color conversion layer: CCM) Method, cathode (counter electrode)
There is a method in which a transparent electrode is used to overlap EL elements corresponding to RGB.

FIG. 4 shows three types of E corresponding to RGB.
This is an example in which a method of forming an L element is used. In addition,
Although only one pixel is shown in FIG. 4, pixels having the same structure are formed corresponding to the respective colors of red, green and blue, whereby color display can be performed.

The present invention can be carried out irrespective of the light emitting method, and all the above four methods can be used in the present invention. However, since the fluorescent substance has a slow response speed as compared with the EL and may cause a problem of afterglow, a method using no fluorescent substance is desirable. In addition, it can be said that it is desirable not to use a color filter, which causes a reduction in light emission luminance, as much as possible.

The cathode 52 of the EL element is provided on the EL layer 51. As the cathode 52, a material containing magnesium (Mg), lithium (Li), or calcium (Ca) having a small work function is used. Preferably MgAg
(Material in which Mg and Ag are mixed at Mg: Ag = 10: 1)
May be used. In addition, MgAgAl electrode,
A LiAl electrode and a LiFAl electrode are mentioned.

After forming the EL layer 51, the cathode 52 is desirably formed continuously without opening to the atmosphere. Cathode 5
This is because the interface state between 2 and the EL layer 51 greatly affects the luminous efficiency of the EL element. Note that in this specification, a light-emitting element formed by a pixel electrode (anode), an EL layer, and a cathode is referred to as an EL element.

The laminate composed of the EL layer 51 and the cathode 52 is
Although it is necessary to individually form each pixel, the EL layer 51 is extremely weak against moisture, so that ordinary photolithography cannot be used. Therefore, it is preferable to selectively form the film by a vapor phase method such as a vacuum evaporation method, a sputtering method, and a plasma CVD method using a physical mask material such as a metal mask.

After the EL layer is selectively formed using an ink jet method, a screen printing method, a spin coating method, or the like, a cathode may be formed by a vapor phase method such as a vapor deposition method, a sputtering method, and a plasma CVD method. It is possible.

Reference numeral 53 denotes a protective electrode, which protects the cathode 52 from external moisture and the like, and at the same time, the cathode 52 of each pixel.
Is an electrode for connecting. As the protection electrode 53,
Aluminum (Al), copper (Cu) or silver (Ag)
It is preferable to use a low-resistance material containing The protective electrode 53 can also be expected to have a heat radiation effect of reducing heat generation of the EL layer. After forming the EL layer 51 and the cathode 52,
It is also effective to form up to the protection electrode 53 continuously without opening to the atmosphere.

A second passivation film 54 has a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). The purpose of providing the second passivation film 54 is mainly to protect the EL layer 51 from moisture, but it is also effective to have a heat radiation effect. However, as described above, since the EL layer is weak to heat, it is desirable to form the film at a temperature as low as possible (preferably in a temperature range from room temperature to 120 ° C.). Therefore, it can be said that a plasma CVD method, a sputtering method, a vacuum evaporation method, an ion plating method, or a solution coating method (spin coating method) is a preferable film forming method.

The gist of the present invention is that, in an active matrix type EL display device, a change in environment is detected by a sensor, the amount of current flowing through the EL element is controlled based on this information, and the luminance of the EL element is controlled. It is.
Therefore, the present invention is not limited to the structure of the EL display device shown in FIG. 4, and the structure shown in FIG. 4 is merely one of preferred embodiments for implementing the present invention.

[0085]

[Embodiment 1] In this embodiment, as the surrounding environment information, the surrounding brightness environment information is stored in a photodiode, Cd.
The present invention relates to an EL display having a display system that detects light with an S photoconductive element (cadmium sulfide photoconductive element), a light receiving element such as a CCD or CMOS sensor, and adjusts the luminance of the EL element based on the detected environmental information signal. FIG. 5 shows a schematic configuration diagram thereof. Reference numeral 501 denotes a brightness-compatible EL display in which an EL display device is mounted on a display unit of a notebook personal computer. 5
02 is an EL display device. A photodiode 503 detects an ambient brightness environment information signal. The photodiode inputs the detected environmental information signal to the A / D conversion circuit as an analog electric signal. The environmental information signal converted into a digital environmental information signal by the A / D conversion circuit is input to the CPU. In the CPU, the input environmental information signal is converted into a correction signal for obtaining desired brightness, and the correction signal is input to the D / A conversion circuit. The correction signal converted into an analog correction signal by the D / A conversion circuit is
When input to the voltage variable device, a corresponding correction potential is applied.

The brightness-compatible EL display of this embodiment is not only a photodiode but also a light receiving element such as a CdS photoconductive element, a CCD and a CMOS sensor, and further obtains biological information of a user to obtain biological information. It may have a sensor for converting into a signal, a speaker or headphones for outputting voice or music, a VCR or a computer for supplying an image signal.

FIG. 6 is an external view of a brightness-compatible EL display of this embodiment. Brightness compatible EL display 701, display unit 702, photodiode 7
03, a voltage variable device 704, a keyboard 705, and the like. In this embodiment, the EL display device is used for the display portion 702.

The arrangement and number of the photodiodes 703 for monitoring the surrounding brightness are not limited to those shown in FIG.

Next, the operation and functions of the brightness-compatible EL display of this embodiment will be described. FIG. 5 is referred to again. During normal use, the brightness-compatible display according to the present embodiment transmits an image signal from an external device to an EL device.
Supply to the display device. Examples of the external device include a personal computer, a portable information terminal, and a VCR. The user observes the image projected on the EL display device.

The brightness-corresponding EL display 501 of this embodiment is provided with a photodiode 503 for detecting the surrounding brightness as a surrounding environment information signal and converting the environment information signal into an electric signal. . The electric signal detected by the photodiode 503 is converted into a digital environmental information signal by an A / D converter 504, and then converted to a CP.
It is input to U505. The CPU 505 converts the input environment information signal into a correction signal for correcting the emission luminance of the EL element based on preset comparison data. The correction signal converted by the CPU 505 is input to the D / A converter 506 and converted into an analog correction signal.
When the analog correction signal is input to the voltage variable device 507, the voltage variable device 507 applies a predetermined correction potential. Thus, the potential difference between the EL drive potential and the correction potential is controlled, and the emission luminance of the EL element can be raised or lowered according to the surrounding brightness. Specifically, when the surroundings are bright, the emission luminance of the EL element is increased, and when the surroundings are dark, the emission luminance of the EL element is decreased.

FIG. 7 is a flowchart showing the operation of the brightness-compatible EL display of this embodiment. In the brightness-compatible EL display of this embodiment, an image signal from an external device (for example, a personal computer or a video deck) is usually supplied to the EL display.
Further, in the present embodiment, the photodiode detects the ambient brightness environment information signal, and converts the A / D signal into an electrical signal.
After input to the converter, the converted digital electrical signal is input to the CPU. Further, after being converted into a correction signal reflecting the ambient brightness by the CPU, it is converted into an analog correction signal by a D / A converter, and when this is input to a voltage variable device, a desired correction potential is applied to the EL element. Is done. Thereby, the light emission luminance of the EL display device is controlled.

The above operation is repeated.

By performing the present embodiment as described above, it is possible to adjust the light emission luminance of the image of the EL display device according to the surrounding brightness environment information, and it is possible to emit more light than necessary from the EL element It is possible to suppress deterioration of the EL element due to current flowing.

Next, FIG. 8 is a sectional view of a pixel portion of an EL display device according to this embodiment, FIG. 9A is a top view thereof, and FIG. 9B is a circuit configuration thereof. Actually, a plurality of pixels are arranged in a matrix to form a pixel portion (image display portion). Note that FIG. 9 is a cross-sectional view taken along a line AA ′ in FIG. 9A. Therefore, since the same reference numerals are used in FIGS. 8 and 9, it is better to refer to both drawings as appropriate. Also,
Although two pixels are shown in the top view of FIG. 9, both have the same structure.

In FIG. 8, reference numeral 11 denotes a substrate, and 12 denotes an insulating film serving as a base (hereinafter, referred to as a base film). As the substrate 11, a glass substrate, a glass ceramic substrate, a quartz substrate, a silicon substrate, a ceramic substrate, a metal substrate, or a plastic substrate (including a plastic film) can be used.

The base film 12 is particularly effective when a substrate containing mobile ions or a substrate having conductivity is used, but may not be provided on a quartz substrate. As the base film 12, an insulating film containing silicon (silicon) may be used. Note that in this specification, the “insulating film containing silicon” specifically includes silicon, oxygen, or nitrogen at a predetermined ratio, such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film (indicated by SiOxNy). Refers to an insulating film.

Dispersing the heat generated by the TFT by providing the base film 12 with a heat radiation effect is also effective in preventing the deterioration of the TFT or the EL element. All known materials can be used to provide a heat radiation effect.

Here, two TFTs are formed in a pixel. Reference numeral 201 denotes a switching TFT formed of an n-channel TFT, and reference numeral 202 denotes a current control TFT formed of a p-channel TFT.

However, in the present invention, it is not necessary to limit the switching TFT to an n-channel TFT and the current control TFT to a p-channel TFT. The switching TFT is a p-channel TFT and the current control TFT is an n-channel TFT. It is also possible to use an n-type TFT or a p-channel type TFT for both.

The switching TFT 201 includes a source region 13, a drain region 14, LDD regions 15a to 15d,
High concentration impurity region 16 and channel forming regions 17a, 1
Active layer including 7b, gate insulating film 18, gate electrode 19
a, 19b, a first interlayer insulating film 20, a source wiring 21, and a drain wiring 22.

Further, as shown in FIG.
A and 19b have a double gate structure electrically connected by a gate wiring 211 formed of another material (a material having a lower resistance than the gate electrodes 19a and 19b). Of course, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel forming regions connected in series) such as a triple gate structure may be used. The multi-gate structure is extremely effective in reducing the off-state current value. In the present invention, a switching element with a low off-state current value is realized by using a multi-gate structure for the pixel switching element 201.

The active layer is formed of a semiconductor film having a crystal structure. That is, a single crystal semiconductor film, a polycrystalline semiconductor film, or a microcrystalline semiconductor film may be used. Further, the gate insulating film 18 may be formed using an insulating film containing silicon. As the gate electrode, the source wiring, or the drain wiring, any conductive film can be used.

Further, in the switching TFT 201, the LDD regions 15a to 15d
Are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing the off-current value.

It is more preferable to provide an offset region (a region made of a semiconductor layer having the same composition as the channel formation region and to which no gate voltage is applied) between the channel formation region and the LDD region in order to reduce the off-current value. . In the case of a multi-gate structure including two or more gate electrodes, a high-concentration impurity region provided between channel formation regions is effective in reducing an off-current value.

As described above, a multi-gate TFT
Is used as the switching element 201 of the pixel, a switching element with sufficiently low off-state current can be realized. Therefore, Japanese Patent Application Laid-Open No. 10-189252
The gate voltage of the current controlling TFT can be maintained for a sufficient time (between selection and the next selection) without providing a capacitor as shown in FIG.

Next, the current controlling TFT 202 includes the source region 27, the drain region 26, and the channel forming region 29.
, A gate insulating film 18, a gate electrode 30, a first interlayer insulating film 20, a source wiring 31 and a drain wiring 32. The gate electrode 30 has a single gate structure, but may have a multi-gate structure.

As shown in FIG. 8, the switching TFT
The drain of 201 is connected to the gate of the current control TFT 202. Specifically, the gate electrode 30 of the current control TFT 202 is connected to the drain region 14 and the drain wiring (also referred to as connection wiring) 22 of the switching TFT 201.
Are electrically connected via Also, the source wiring 3
1 is connected to a power supply line.

The current control TFT 202 is an EL element 203
Is an element for controlling the amount of current injected into the
Considering the deterioration of the L element, it is not preferable to flow too much current. Therefore, it is preferable to design the channel length (L) to be longer so that an excessive current does not flow through the current controlling TFT 202. Desirably, it is 0.5 to 2 μA (preferably 1 to 1.5 μA) per pixel.

The length (width) of the LDD region formed in the switching TFT 201 is 0.5 to 3.5 μm.
Typically, the thickness may be 2.0 to 2.5 μm.

From the viewpoint of increasing the amount of current that can flow, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 202 is increased (preferably 50).
To 100 nm, more preferably 60 to 80 nm). Conversely, in the case of the switching TFT 201, from the viewpoint of reducing the off-current value, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40 n).
m) is also effective.

Next, a first passivation film 47 has a thickness of 10 nm to 1 μm (preferably 200 to 50 μm).
0 nm). As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used.

On the first passivation film 47, a second interlayer insulating film (which may be referred to as a flattening film) 48 is formed so as to cover each TFT, and a step formed by the TFT is flattened. . As the second interlayer insulating film 48, an organic resin film is preferable, and polyimide, polyamide, acrylic,
BCB (benzocyclobutene) or the like is preferably used. Of course, if sufficient planarization is possible, an inorganic film may be used.

It is very important that the step caused by the TFT is flattened by the second interlayer insulating film 48. Since an EL layer formed later is extremely thin, poor light emission may be caused by the presence of a step. Therefore, it is desirable that the EL layer be flattened before forming the pixel electrode so that the EL layer can be formed as flat as possible.

Reference numeral 49 denotes a pixel electrode (corresponding to an anode of an EL element) formed of a transparent conductive film. After a contact hole (opening) is formed in the second interlayer insulating film 48 and the first passivation film 47, The opening is formed so as to be connected to the drain wiring 32 of the current control TFT 202.

In this embodiment, a conductive film made of a compound of indium oxide and tin oxide is used as a pixel electrode. Further, a small amount of gallium may be added thereto.

An EL layer 51 is formed on the pixel electrode 49. In this embodiment, a polymer organic substance is formed by spin coating. As the polymer organic substance, any known material can be used. Further, in this embodiment, a single light emitting layer is used as the EL layer 51, but a stacked structure in which a hole transporting layer or an electron transporting layer is combined has higher luminous efficiency. However, when a polymer organic substance is laminated, it is desirable to combine it with a low molecular organic substance formed by an evaporation method. In the spin coating method, since an organic substance to be an EL layer is mixed with an organic solvent and applied, there is a possibility that the organic substance will be dissolved again if the underlying substance is present.

Representative polymer organic substances that can be used in this embodiment include polyparaphenylene vinylene (PPV) and polyvinyl carbazole (PVK).
And polyfluorene-based polymer materials.
In order to form an electron transporting layer, a light emitting layer, a hole transporting layer or a hole injecting layer with these polymer organic materials, they are applied in the state of a polymer precursor and heated (baked) in a vacuum. What is necessary is just to convert it into a polymer organic substance.

More specifically, the light emitting layer may be cyanopolyphenylenevinylene for the red light emitting layer, polyphenylenevinylene for the green light emitting layer, and polyphenylenevinylene or polyalkylphenylene for the blue light emitting layer. The film thickness is 30 to 150 nm (preferably 40 to 100 nm)
nm). For the hole transport layer, polytetrahydrothiophenylphenylene, which is a polymer precursor, is used, and is heated to polyphenylenevinylene. The film thickness is 30 to 100 nm (preferably 40 to 80 n
m).

It is also possible to emit white light using a polymer organic substance. For that purpose, Japanese Patent Application Laid-Open
The techniques described in Japanese Patent Application Laid-Open No. 96959, Japanese Patent Application Laid-Open No. 7-220871, Japanese Patent Application Laid-Open No. 9-63770 and the like may be cited. The polymer organic substance can be easily adjusted in color by adding a fluorescent dye to a solution in which a host material is dissolved, and thus is particularly effective when emitting white light.

Although an example in which an EL element is formed using a polymer organic substance is shown here, a low molecular organic substance may be used. Further, an inorganic substance may be used for the EL layer.

The above examples are examples of organic substances that can be used as the EL layer of the present invention, and do not limit the present invention.

When forming the EL layer 51, it is preferable that the processing atmosphere is a dry atmosphere with a minimum amount of moisture and is performed in an inert gas. Since the EL layer is easily deteriorated by the presence of moisture and oxygen, it is necessary to eliminate such factors as much as possible when forming the EL layer. For example, a dry nitrogen atmosphere, a dry argon atmosphere, or the like is preferable. For this purpose, it is preferable that the coating treatment chamber and the baking treatment chamber are installed in a clean booth filled with an inert gas, and the treatment is performed in that atmosphere.

After the EL layer 51 is formed as described above, a cathode 52 made of a light-shielding conductive film, a protection electrode (not shown), and a second passivation film 54 are formed. In this embodiment, a conductive film made of MgAg is used as the cathode 52. The second passivation film 54 has a thickness of 10 nm to 1 μm (preferably 200 to 500 n).
m) of a silicon nitride film.

Since the EL layer is weak to heat as described above, the temperature of the cathode 52 and the second passivation film 54 is as low as possible (preferably in a temperature range from room temperature to 120 ° C.).
It is desirable to form a film. Therefore, the plasma CVD method,
It can be said that a vacuum deposition method or a solution coating method (spin coating method) is a desirable film forming method.

The completed substrate is called an active matrix substrate, and a counter substrate 64 is provided to face the active matrix substrate. In this embodiment, a glass substrate is used as the counter substrate 64.

Further, the active matrix substrate and the counter substrate 64 are bonded with a sealant (not shown), so that a closed space 63 is formed. In this embodiment, the closed space 49 is filled with argon gas. Of course, this closed space 63
It is also possible to arrange a desiccant such as barium oxide therein.

[Embodiment 2] A method for simultaneously manufacturing a TFT of a pixel portion used in the present invention and a driving circuit portion provided around the pixel portion will be described with reference to FIGS. However,
For the sake of simplicity, a CMOS circuit, which is a basic circuit, will be illustrated for the drive circuit.

First, as shown in FIG. 10A, a base film 301 is formed on a glass substrate 300 to a thickness of 300 nm. In this embodiment, a 100-nm-thick silicon nitride oxide film and a 200-nm silicon nitride oxide film are stacked and used as the base film 301. At this time, the nitrogen concentration in contact with the glass substrate 300 is preferably set to 10 to 25 wt%. Of course, an element may be formed directly on a quartz substrate without providing a base film.

It is effective to provide an insulating film made of the same material as the first passivation film 47 shown in FIG. 4 as a part of the base film 301. Current control TFT
Since a large current flows, heat is easily generated, and it is effective to provide an insulating film having a heat radiation effect as close as possible.

Next, an amorphous silicon film (not shown) having a thickness of 50 nm is formed on the base film 301 by a known film forming method. Note that the present invention is not limited to an amorphous silicon film, and may be any semiconductor film including an amorphous structure (including a microcrystalline semiconductor film). Further, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used. The film thickness is 2
The thickness may be 0 to 100 nm.

Then, the amorphous silicon film is crystallized by a known technique, and a crystalline silicon film (also called a polycrystalline silicon film or a polysilicon film) 302 is formed. Known crystallization methods include a thermal crystallization method using an electric furnace, a laser annealing crystallization method using laser light, and a lamp annealing crystallization method using infrared light. In this embodiment, X
Crystallization is performed using excimer laser light using eCl gas.

In this embodiment, a pulse oscillation type excimer laser beam processed into a linear shape is used, but a rectangular shape may be used, or a continuous oscillation type argon laser beam or a continuous oscillation type excimer laser beam may be used. You can also.

In this embodiment, a crystalline silicon film is used as an active layer of a TFT, but an amorphous silicon film can be used. Further, it is also possible to form the active layer of the switching TFT, which needs to reduce the off current, with an amorphous silicon film, and to form the active layer of the current control TFT with a crystalline silicon film. Since the amorphous silicon film has a low carrier mobility, it is difficult for an electric current to flow and an off current is hard to flow. That is, the advantages of both an amorphous silicon film through which a current is hard to flow and a crystalline silicon film through which a current easily flows can be utilized.

Next, as shown in FIG. 10B, a protective film 303 made of a silicon oxide film is formed on the crystalline silicon film 302 by one step.
It is formed to a thickness of 30 nm. This thickness is 100-200
nm (preferably 130 to 170 nm). Further, any other insulating film containing silicon may be used. The protective film 303 is provided to prevent the crystalline silicon film from being directly exposed to plasma when adding impurities and to enable fine concentration control.

Then, a resist mask 304 is formed thereon.
a and 304b are formed, and an impurity element imparting n-type (hereinafter, referred to as an n-type impurity element) is added via the protective film 303. Note that the n-type impurity element is typically 15
Elements belonging to the group, typically phosphorus or arsenic, can be used. In this embodiment, the plasma (ion) in which phosphine (PH ₃ ) is plasma-excited without mass separation.
Using a doping method, phosphorus is added at a concentration of 1 × 10 ¹⁸ atoms / cm ³ . Of course, an ion implantation method for performing mass separation may be used.

In the n-type impurity region 305 formed in this step, the n-type impurity element is 2 × 10 ^{16 to} 5 × 10 ¹⁹
atoms / cm ³ (typically 5 × 10 ^{17 to} 5 × 10 ¹⁸ atoms / c
Adjust the dose so that it is contained at a concentration of m ³ ).

Next, as shown in FIG. 10C, the protective film 303 and the resists 304a and 304b are removed, and the added elements belonging to group 15 are activated. As the activating means, a known technique may be used. In this embodiment, the activating means is activated by excimer laser light irradiation. Needless to say, a pulse oscillation type or a continuous oscillation type may be used, and it is not necessary to limit to an excimer laser beam. However, since the purpose is to activate the added impurity element, it is preferable that the irradiation be performed with energy that does not melt the crystalline silicon film. The protective film 3
The laser beam may be irradiated with 03 attached.

When activating the impurity element by the laser beam, activation by heat treatment may be used in combination. When activation by heat treatment is performed, heat treatment at about 450 to 550 ° C. may be performed in consideration of the heat resistance of the substrate.

By this step, the n-type impurity region 305, ie, the n-type impurity region
The boundary (junction) with the region where the type impurity element is not added becomes clear. This means that when the TFT is completed later, a very good junction can be formed between the LDD region and the channel forming region.

Next, as shown in FIG. 10D, unnecessary portions of the crystalline silicon film are removed to form island-shaped semiconductor films (hereinafter, referred to as active layers) 306 to 309.

Next, as shown in FIG. 10E, a gate insulating film 310 is formed to cover the active layers 306 to 309. 10 to 200 nm as the gate insulating film 310;
Preferably, an insulating film containing silicon with a thickness of 50 to 150 nm is used. This may have a single-layer structure or a laminated structure. In this embodiment, a 110-nm-thick silicon nitride oxide film is used.

Next, a conductive film having a thickness of 200 to 400 nm is formed and patterned to form gate electrodes 311 to 315. The ends of the gate electrodes 311 to 315 can be tapered. Note that in this embodiment, the gate electrode and a wiring for wiring (hereinafter, referred to as a gate wiring) electrically connected to the gate electrode are formed using different materials. Specifically, a material having lower resistance than the gate electrode is used for the gate wiring. This is because a material that can be finely processed is used for the gate electrode, and a material that does not allow fine processing and has low wiring resistance is used for the gate wiring.
Of course, the gate electrode and the gate wiring may be formed of the same material.

The gate electrode may be formed of a single-layer conductive film, but is preferably formed as a two-layer or three-layer film as required. As a material for the gate electrode, any known conductive film can be used. However, a material that can be finely processed as described above, specifically, a material that can be patterned into a line width of 2 μm or less is preferable.

Representatively, tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W),
A film made of an element selected from chromium (Cr) and silicon (Si), a nitride film of the above element (typically, a tantalum nitride film, a tungsten nitride film, a titanium nitride film), or an alloy combining the above elements Membrane (typically Mo-W
Alloy, a Mo—Ta alloy), or a silicide film of the above element (typically, a tungsten silicide film or a titanium silicide film) can be used. Of course, they may be used as a single layer or stacked.

In this embodiment, a laminated film composed of a 50 nm-thick tantalum nitride (TaN) film and a 350 nm-thick tantalum (Ta) film is used. This may be formed by a sputtering method. When an inert gas such as Xe or Ne is added as a sputtering gas, the film can be prevented from peeling due to stress.

At this time, the gate electrode 312 is formed so as to overlap a part of the n-type impurity region 305 with the gate insulating film 310 interposed therebetween. This overlapping portion later becomes an LDD region overlapping with the gate electrode. The gate electrode 31
3 and 314 appear to be two in cross section, but are actually electrically connected.

Next, as shown in FIG. 11A, an n-type impurity element (phosphorus in this embodiment) is added in a self-aligned manner using the gate electrodes 311 to 315 as a mask. Impurity regions 316 to 323 thus formed are １ ／ to 1/10 (typically ３ to 1/1) of n-type impurity region 305.
Adjust so that phosphorus is added at the concentration of 4). Specifically, a concentration of 1 × 10 ^{16 to} 5 × 10 ¹⁸ atoms / cm ³ (typically, 3 × 10 ^{17 to} 3 × 10 ¹⁸ atoms / cm ³ ) is preferable.

Next, as shown in FIG. 11B, resist masks 324a to 324d are formed so as to cover the gate electrodes and the like, and an n-type impurity element (phosphorus in this embodiment) is added to increase the concentration. The impurity regions 325 to 329 containing phosphorus are formed. Ion doping using again phosphine (PH _3), the phosphorous concentration of these regions is 1 × 10 ²⁰ to 1
× 10 ²¹ atoms / cm ³ (typically 2 × 10 ^{20 to} 5 × 10
Adjust so as to be ²¹ atoms / cm ³ ).

In this step, the source region or the drain region of the n-channel TFT is formed. In the case of the switching TFT, the n-channel TFT formed in the step of FIG.
A part of the type impurity regions 319 to 321 is left. This remaining region corresponds to the LDD regions 15a to 15d of the switching TFT 201 in FIG.

Next, as shown in FIG. 11C, the resist masks 324a to 324d are removed, and a new resist mask 332 is formed. Then, a p-type impurity element (boron in this embodiment) is added to form impurity regions 333 to 336 containing boron at a high concentration. Here, an ion doping method using diborane (B ₂ H ₆ ) is used to form 3 × 10 ²⁰ to
3 × 10 ²¹ atoms / cm ³ (typically 5 × 10 ²⁰ to 1 × 1
(Boron) is added so as to have a concentration of 0 ²¹ atoms / cm ³ .

Note that phosphorus is already added to the impurity regions 333 to 336 at a concentration of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ , and the boron added here is at least three times as large as that. It is added at a concentration. Therefore, the n-type impurity region formed in advance is completely inverted to p-type, and functions as a p-type impurity region.

Next, after removing the resist mask 332, the n-type or p-type impurity element added at each concentration is activated. As the activation means, a furnace annealing method, a laser annealing method, or a lamp annealing method can be used. In this embodiment, heat treatment is performed in an electric furnace at 550 ° C. for 4 hours in a nitrogen atmosphere.

At this time, it is important to eliminate oxygen in the atmosphere as much as possible. This is because the presence of even a small amount of oxygen oxidizes the exposed surface of the gate electrode, causing an increase in resistance and making it difficult to obtain an ohmic contact later. Therefore, the oxygen concentration in the processing atmosphere in the activation step is 1 ppm or less, preferably 0.1 ppm or less.
pm or less.

Next, when the activation step is completed, FIG.
A gate wiring 337 having a thickness of 300 nm is formed as shown in FIG. As a material of the gate wiring 337, aluminum (Al) or copper (Cu) is a main component (composition of 50
Occupies ~ 100%. ) May be used. The arrangement is such that the gate wiring 211 is electrically connected to the gate electrodes 19a and 19b (313 and 314 in FIG. 10E) of the switching TFT as shown in FIG.

With such a structure, the wiring resistance of the gate wiring can be extremely reduced, so that an image display region (pixel portion) having a large area can be formed. That is, the pixel structure of the present embodiment is extremely effective in realizing an EL display device having a screen size of 10 inches or more (more preferably 30 inches or more) diagonally.

Next, as shown in FIG. 12A, a first interlayer insulating film 338 is formed. As the first interlayer insulating film 338, an insulating film containing silicon may be used as a single layer or a stacked film in which two or more insulating films containing silicon are combined. The film thickness may be 400 nm to 1.5 μm. In this embodiment, an 800 nm thick silicon oxide film is stacked over a 200 nm thick silicon nitride oxide film.

Further, a heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% of hydrogen to perform a hydrogenation treatment. This step is a step of terminating dangling bonds of the semiconductor film with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen generated by plasma) may be performed.

The hydrogenation process is performed for the first interlayer insulating film 338.
May be inserted during formation. That is, after forming a 200-nm-thick silicon nitride oxide film, the hydrogenation treatment may be performed as described above, and then a remaining 800-nm-thick silicon oxide film may be formed.

Next, contact holes are formed in the first interlayer insulating film 338 and the gate insulating film 310, and source wirings 339 to 342 and drain wirings 343 to 345 are formed. In the present embodiment, this electrode is used as a Ti film.
00 nm, an aluminum film containing Ti is 300 nm, T
An i film having a thickness of 150 nm is continuously formed by a sputtering method to form a laminated film having a three-layer structure. Of course, other conductive films may be used.

Next, 50 to 500 nm (typically 20 to 500 nm)
The first passivation film 34 with a thickness of
6 is formed. In this embodiment, the first passivation film 3
A silicon nitride oxide film having a thickness of 300 nm is used as 46. This may be replaced by a silicon nitride film. Of course, the same material as the first passivation film 47 in FIG. 4 can be used.

Note that prior to the formation of the silicon nitride oxide film, H
_2. It is effective to perform a plasma treatment using a gas containing hydrogen such as NH ₃ . Hydrogen excited by this pretreatment is supplied to the first interlayer insulating film 338 and is subjected to a heat treatment, whereby the quality of the first passivation film 346 is improved. At the same time, the hydrogen added to the first interlayer insulating film 338 diffuses to the lower layer side, so that the active layer can be effectively hydrogenated.

Next, as shown in FIG. 12B, a second interlayer insulating film 347 made of an organic resin is formed. As the organic resin, polyimide, polyamide, acrylic, BCB (benzocyclobutene), or the like can be used. In particular,
Since the second interlayer insulating film 347 has a strong meaning of flattening,
Acrylic having excellent flatness is preferable. In this embodiment, TF
An acrylic film is formed with a thickness that can sufficiently flatten a step formed by T. The thickness is preferably 1 to 5 μm (more preferably 2 to 4 μm).

Next, a contact hole is formed in the second interlayer insulating film 347 and the first passivation film 346, and a pixel electrode 348 electrically connected to the drain wiring 345 is formed. In this embodiment, an indium tin oxide (ITO) film is formed to a thickness of 110 nm and patterned to form a pixel electrode. In addition, 2 indium oxide
A transparent conductive film mixed with -20% of zinc oxide (ZnO) may be used. This pixel electrode becomes the anode of the EL element.
Note that reference numeral 349 denotes an end of an adjacent pixel electrode.

Next, the EL layer 350 and the cathode (MgAg electrode) 351 are continuously formed by using a vacuum deposition method without opening to the atmosphere. Note that the thickness of the EL layer 350 is 80 to 200.
nm (typically 100-120 nm), and the thickness of the cathode 351 is 180-300 nm (typically 200-250 nm).
nm).

In this step, a pixel corresponding to red, a pixel corresponding to green, and a pixel corresponding to blue are sequentially E
An L layer and a cathode are formed. However, since the EL layer has poor resistance to a solution, it must be formed individually for each color without using a photolithography technique. Therefore, it is preferable that a metal mask is used to hide portions other than the desired pixels, and that the EL layer and the cathode are selectively formed only in necessary portions.

That is, first, a mask for hiding all pixels other than the pixels corresponding to red is set, and the EL layer and the cathode for emitting red light are selectively formed using the mask. Next, a mask for hiding all pixels other than pixels corresponding to green is set, and the EL layer and the cathode for emitting green light are selectively formed using the mask. Next, similarly, a mask for hiding all pixels other than the pixel corresponding to blue is set, and the EL for blue light emission is set using the mask.
The layer and the cathode are selectively formed. Note that all the masks are described herein as being different, but the same mask may be used again. In addition, it is preferable to perform processing without breaking vacuum until an EL layer and a cathode are formed in all pixels.

A known material can be used for the EL layer 350. As a known material, it is preferable to use an organic material in consideration of a driving voltage. Note that in this embodiment, the EL layer 350 has a single-layer structure including only the light-emitting layer.
If necessary, an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, an electron blocking layer, or a hole element layer may be provided. In this embodiment, the cathode 351 of the EL element is M
Although an example using a gAg electrode is shown, other known materials may be used.

[0168] As the protective electrode 352, a conductive film containing aluminum as a main component may be used. Protection electrode 35
2 may be formed by a vacuum evaporation method using a mask different from that used when the EL layer and the cathode are formed. After the EL layer and the cathode are formed, they are preferably formed continuously without being released to the atmosphere.

Lastly, a second passivation film 353 made of a silicon nitride film is formed to a thickness of 300 nm. Although the protection electrode 352 actually serves to protect the EL layer from moisture and the like, the reliability of the EL element can be further increased by forming the second passivation film 353 further.

Thus, an active matrix EL display device having a structure as shown in FIG. 12C is completed. Actually, when completed up to FIG. 12 (C), packaging with a housing material such as a highly airtight protective film (laminated film, ultraviolet curable resin film, etc.) or a ceramic sealing can so as not to be further exposed to the outside air. (Encapsulation). At this time, the reliability (lifetime) of the EL layer can be improved by setting the inside of the housing material to an inert atmosphere or arranging a hygroscopic material (for example, barium oxide) inside.

Thus, an active matrix EL display device having a structure as shown in FIG. 12C is completed. By the way, the active matrix EL display device of the present embodiment has a TF having an optimal structure not only for the pixel portion but also for the drive circuit portion.
By arranging T, very high reliability can be exhibited and operating characteristics can be improved.

First, a TFT having a structure in which hot carrier injection is reduced so as not to lower the operation speed as much as possible,
N-channel type TFT of CMOS circuit forming drive circuit
Used as 205. Note that the drive circuit here includes a shift register, a buffer, a level shifter, a sampling circuit (a sample and hold circuit), and the like. When digital driving is performed, a signal conversion circuit such as a D / A converter may be included.

In the case of this embodiment, as shown in FIG. 12C, the active layer of the n-channel TFT 205 includes a source region 355, a drain region 356, an LDD region 357, and a channel forming region 358, and the LDD region 357 Overlaps the gate electrode 312 with the gate insulating film 311 interposed therebetween.

The reason why the LDD region is formed only on the drain region side is to avoid lowering the operation speed.
Further, the n-channel TFT 205 does not need to care much about the off-current value, and it is better to emphasize the operation speed. Therefore, it is desirable that the LDD region 357 be completely overlapped with the gate electrode and the resistance component be reduced as much as possible. That is, it is better to eliminate the so-called offset.

Also, a p-channel type TFT of a CMOS circuit
In 206, since the deterioration due to hot carrier injection is hardly noticeable, an LDD region need not be particularly provided. Of course, it is also possible to provide an LDD region similarly to the n-channel type TFT 205 and take measures against hot carriers.

Note that among the driving circuits, the sampling circuit is a little special as compared with other circuits, and a large current flows in both directions in the channel forming region. That is, the roles of the source region and the drain region are switched. In addition, it is necessary to keep the off-current value as low as possible, and in that sense, it is desirable to arrange a TFT having a function approximately between the switching TFT and the current control TFT.

Therefore, it is desirable to arrange a TFT having a structure as shown in FIG. 13 as the n-channel TFT forming the sampling circuit. As shown in FIG.
Part of the regions 901 a and 901 b overlap with the gate electrode 903 with the gate insulating film 902 interposed therebetween. This effect is as described in the description of the current control TFT 202, and is different in that a sampling circuit is provided so as to sandwich the channel formation region 904.

Note that when the process is completed up to FIG. 12C, the active matrix substrate and the counter substrate are bonded with a sealant. At that time, the inside of the sealed space between the active matrix substrate and the counter substrate is set to an inert atmosphere,
When a hygroscopic material (for example, barium oxide) is disposed inside, the reliability (lifetime) of the EL layer included therein can be improved. You.

[Embodiment 3] Next, the structure of an active matrix type EL display device of this embodiment will be described with reference to the perspective view of FIG. Active matrix EL of this embodiment
The display device includes a pixel portion 602, a gate driver circuit 603, and a source driver circuit 604 formed over a glass substrate 601. Pixel switching TFT
Reference numeral 605 denotes an n-channel TFT, which is arranged at the intersection of a gate wiring 606 connected to the gate driver circuit 603 and a source wiring 607 connected to the source driver circuit 604. The drain of the switching TFT 605 is connected to the gate of the current control TFT 608.

The source side of the current controlling TFT 608 is connected to a power supply line 609. Further, a capacitor 615 connected between the gate region of the current controlling TFT 608 and the power supply line 609 is provided. In the structure of this embodiment, the power supply line 609 is supplied with the EL drive potential. The current control TF
The EL element 610 is connected to the drain of T608. In addition, a correction potential corresponding to external environmental information is applied to a side of the EL element 610 that is not connected to the current control TFT by a voltage variable device (not shown).

The FPC 61 serving as an external input / output terminal
1 includes input / output wirings (connection wirings) 612 and 613 for transmitting signals to the drive circuit, and input / output wirings 614 connected to the power supply line 609.

Further, an EL display device of this embodiment including a housing material will be described with reference to FIGS. Note that the reference numerals used in FIG. 14 will be referred to as needed.

On the substrate 1500, the pixel portion 1501, the data signal side driving circuit 1502, and the gate signal side driving circuit 15
03 is formed. Various wirings from the respective drive circuits are supplied to the FPC 611 via input / output wirings 612 to 614.
And connected to the external device.

At this time, the housing member 150 is formed so as to surround at least the pixel portion, preferably the drive circuit and the pixel portion.
4 is provided. Note that the housing material 1504 has a shape having a concave portion whose inner size is larger than the outer size of the EL element or a sheet shape, and is fixed to the substrate 1500 by an adhesive 1505 so as to form a closed space together with the substrate 1500. Is done. At this time, the EL element is completely sealed in the closed space, and is completely shut off from the outside air. Note that a plurality of housing members 1504 may be provided.

The material of the housing member 1504 is preferably an insulating material such as glass or polymer. For example, amorphous glass (borosilicate glass, quartz, etc.), crystallized glass,
Ceramic glass, organic resin (acrylic resin, styrene resin, polycarbonate resin, epoxy resin, etc.), and silicon resin are exemplified. Further, ceramics may be used. If the adhesive 1505 is an insulating substance, a metal material such as a stainless alloy can be used.

As the material of the adhesive 1505, an adhesive such as an epoxy resin or an acrylate resin can be used. Further, a thermosetting resin or a photocurable resin can be used as the adhesive. However, it is necessary that the material does not transmit oxygen and moisture as much as possible.

Further, a space 1506 between the housing material and the substrate 1500 is formed by an inert gas (argon, helium,
Nitrogen or the like). Further, not only gas but also an inert liquid (liquid fluorinated carbon represented by perfluoroalkane or the like) can be used. As the inert liquid, a material such as that used in JP-A-8-78519 may be used.

It is also effective to provide a desiccant in the space 1506. As a desiccant, JP-A-9-1480
No. 66 can be used. Typically, barium oxide may be used.

Further, as shown in FIG. 15B, a plurality of pixels having individually isolated EL elements are provided in the pixel portion, and all of them have the protective electrode 1507 as a common electrode. In this embodiment, it is preferable that the EL layer, the cathode (MgAg electrode), and the protection electrode are formed continuously without opening to the atmosphere. However, the EL layer and the cathode are formed using the same mask material, and only the protection electrode is separately formed. 15B, the structure shown in FIG. 15B can be realized.

At this time, the EL layer and the cathode need only be provided in the pixel portion, and need not be provided on the driving circuit. Of course, there is no problem even if it is provided on the drive circuit.
Considering that the layer contains an alkali metal, it is preferable not to provide the layer.

The protection electrode 1507 is connected to an input / output wiring 1509 via a connection wiring 1508 made of the same material as the pixel electrode in a region 1508. The input / output wiring 1509 is a power supply line for applying a predetermined voltage (ground potential, specifically, 0 V in this embodiment) to the protection electrode 1507, and is electrically connected to the FPC 611 through the anisotropic conductive film 1510. Connected.

In the state shown in FIG. 15 described above, an image can be displayed on the pixel portion by connecting the FPC 611 to a terminal of an external device. In this specification,
An article in which an image can be displayed by attaching an FPC, that is, an article in which an active matrix substrate and a counter substrate are attached to each other (including a state in which the FPC is attached) is defined as an EL display device.

The structure of this embodiment can be freely combined with any of the structures of Embodiments 1 and 2.

[Embodiment 4] In the present embodiment, the biological information of a user is detected by a CCD, and E is detected according to the biological information of the user.
The present invention relates to an EL display having a display system for adjusting light emission luminance of an L element, and FIG. 16 shows a schematic configuration diagram thereof. Reference numeral 1601 denotes a goggle type EL display. 1602-L and 1602-
R is an EL display device L and an EL display device R. In this specification, symbols such as (-R) and (-L) may be added after the symbols, but these symbols mean that they are components for the right eye and the left eye, respectively. .
1603-L and 1603-R are CCD-L and C
The CD-R captures images of the left eye and the right eye of the user and detects the biological information signal L and the biological information signal R, respectively.
The detected biological information signal L and biological information signal R are CC
The electric signal L and the electric signal R are input to the A / D converter 1604 by the D-L and the CCD-R, respectively.
The electric signal L and the electric signal R are converted into a digital electric signal L and a digital electric signal R by an A / D converter 1604, and then input to the CPU 1605. The CPU converts the input digital electric signal L and digital electric signal R into a correction signal L and a correction signal R according to the degree of redness of the eyes of the user. The correction signal L and the correction signal R are D / A
Digital correction signal L and correction signal R input to the converter
Is converted. When the digital correction signal L and the correction signal R are input to the voltage variable device 1607, the voltage variable device 1607
Applies a correction potential L and a correction potential R according to the digital correction signal L and the digital correction signal R to the respective EL elements. Note that 1608-L and 1608-R
Are the left and right eyes of the user, respectively.

The goggle type EL display of the present embodiment is not limited to the CCD used in the present embodiment, but also includes a sensor for obtaining a biological information signal of a user including a CMOS sensor and converting the signal into an electric signal, and a sound or voice signal. A speaker or headphones for outputting music or the like, a video deck or a computer for supplying image signals may be provided.

FIG. 17 is an external view of the goggle type EL display of this embodiment.

Goggle type EL display 1701
Are the EL display device L (1702-L) and the EL display device R
(1702-R), CCD-L (1703-L), CC
DR (1703-R), voltage changer-L (1704-R)
L) and a voltage variable device-R (1704-R).
Although not shown in FIG. 17, a goggle type EL
The display is an A / D converter, C
It has a PU and a D / A converter.

A CCD-L for detecting the user's eyes
(1703-L) and CCD-R (1703-R)
Is not limited to the arrangement shown in FIG. In addition, it is also possible to newly provide a sensor for detecting surrounding environment information as shown in the first embodiment.

Here, the operation and function of the goggle type EL display of this embodiment will be described. FIG.
Will be referred to again. In the goggle type EL display of the present embodiment, during normal use, an image signal L and an image signal R are supplied from an external device to the EL display devices 1602-L and 1602-R. Examples of the external device include a personal computer, a portable information terminal, and a VCR. The user uses the EL display device 1602-
The images displayed on L and 1602-R are observed.

The goggle type EL display 1601 of this embodiment has a CCD-L for detecting an image of the user's eye as user's biological information and detecting the image as an electric signal.
1603-L and CCD-R1603-R. The electric signal for the eye image detected here is an electric signal of a color recognized in the white-eye part by selecting only the white-eye part of the user's eyes excluding the black-eye part. CCD-L1603-L and CCD-R1603
Each electric signal detected by -R is input to the A / D converter 1604, and is converted from an analog electric signal to a digital electric signal. This digital electric signal is input to the CPU 1605 and converted into a correction signal.

The CPU 1605 detects the degree of redness of the eyes of the user by gradually including the red information signal in the white information signal recognized by the white-eye portion in the input digital electric signal, Determine if the user is feeling tired. Further, since comparison data for adjusting the light emission luminance of the EL element with respect to the user's eye fatigue level is preset in the CPU 1605, the CPU 1605 controls the light emission luminance corresponding to the user's eye fatigue degree. It is converted into a correction signal. Here, the correction signal is converted into an analog correction signal by the D / A converter 1606 and input to the voltage variable device 1607. This analog correction signal is sent to the voltage
When the voltage is input to 607, the voltage variable unit 1607 applies a predetermined correction potential to the EL element, and the light emission luminance of the EL element is controlled.

Next, FIG. 18 shows the goggle type E of this embodiment.
4 shows an operation flowchart of an L display. In the goggle type EL display of the present embodiment, an image signal is supplied from an external device to the EL display. At this time, a biological information signal of the user is detected by the CCD, and an electric signal detected by the CCD is input to the A / D converter.
The electric signal converted into a digital signal by the A / D converter is:
Further, the data is converted into a correction signal reflecting the biological information of the user in the CPU. The correction signal is converted into an analog correction signal by a D / A converter and is input to a voltage variable device. As a result, a correction potential is applied to the EL element, and the luminance of the EL element is adjusted.

The above operation is repeated.

As the biometric information of the user, the biometric information of the user can be obtained from various parts such as the head, eyes, ears, nose and mouth of the user as well as the degree of redness of the eyes.

As described above, when an abnormality in the degree of redness of the user's eyes is recognized, the emission luminance of the EL display device can be reduced according to the abnormality. This makes it possible to provide a display that is easy on the eyes in response to the abnormality of the user's body.

The structure of this embodiment can be freely combined with any of the structures of the first to third embodiments.

[Embodiment 5] Next, a description will be given, with reference to FIG. 19, of a production method for improving the contact structure in the pixel portion described in FIG. The numbers in FIG. 19 correspond to the numbers in FIG. According to the process of the first embodiment, a state in which the pixel electrode (anode) 43 forming the EL element is provided as shown in FIG.

Next, the contact portion 1900 on the pixel electrode is filled with acrylic, and a contact hole protection portion 1901 is provided as shown in FIG. Here, an acrylic film is formed by a spin coating method, exposed to light using a resist mask, and then etched, whereby FIG.
Is formed as shown in FIG.

The contact hole protection section 1901
Has a thickness of 0.3 to 1 at a portion raised from the pixel electrode when viewed from the cross section (a portion indicated by Da in FIG. 19B).
It is preferably μm. Contact hole protection section 19
When 01 is formed, an EL layer 45 is formed as shown in FIG. 19C, and a cathode 46 is further formed. The method of Embodiment 1 may be used as a method for forming the EL layer 45 and the cathode 46.

The contact hole protection portion 1901 is preferably made of an organic resin, and is preferably made of a material such as polyimide, polyamide, acrylic, or BCB (benzocyclobutene). When these organic resins are used, the viscosity is preferably 10 ⁻³ Pa · s to 10 ⁻¹ Pa · s.

With the structure as shown in FIG. 19C as described above, the E level is reduced at the step of the contact hole.
The pixel electrode 43 and the cathode 4 generated when the L layer 45 is cut
The problem of a short circuit between the wires 6 can be solved.

The structure of this embodiment can be freely combined with any of the structures of the first to fourth embodiments.

[Embodiment 6] An EL display device formed according to the present invention is of a self-luminous type, so that it has better visibility in a bright place than a liquid crystal display device, and has a wide viewing angle. Therefore, it can be used as a display portion of various electric appliances. For example, to watch a TV broadcast or the like on a large screen, an E of 30 inches or more (typically, 40 inches or more) of diagonal is used.
The EL display device of the present invention may be used as a display unit of an L display (a display in which an EL display device is incorporated in a housing).

[0214] The EL display includes all displays for displaying information such as a display for a personal computer, a display for receiving a TV broadcast, and a display for displaying an advertisement. In addition, the EL display device of the present invention can be used as a display portion of various electric appliances.

Examples of such electric appliances include a video camera, a digital camera, a goggle-type display (head-mounted display), a car navigation system, a car audio, a game machine, and a portable information terminal (mobile computer, portable telephone, portable game machine). Or an image reproducing apparatus provided with a recording medium (specifically, a compact disk (CD), a laser disk (registered trademark) (LD), or a digital video disk (DV)).
D) and the like, a device having a display capable of reproducing a recording medium and displaying its image). In particular, for a portable information terminal that is often viewed from an oblique direction, it is important to use an EL display device because a wide viewing angle is regarded as important. FIG. 20 shows specific examples of these electric appliances.

FIG. 20A shows an EL display.
A housing 2001, a support base 2002, a display portion 2003, and the like are included. The present invention can be used for the display portion 2003. E
Since the L display is a self-luminous type, it does not require a backlight and can be a display portion thinner than a liquid crystal display.

FIG. 20B shows a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, and an image receiving portion 210.
6 and so on. The EL display device of the present invention can be used for the display portion 2102.

FIG. 20C shows a part (one right side) of the head-mounted EL display, which includes a main body 2201, a signal cable 2202, a head-fixing band 2203, and a display unit 2.
204, an optical system 2205, an EL display device 2206, and the like. The present invention can be used for the EL display device 2206.

FIG. 20D shows an image reproducing apparatus (specifically, a DVD reproducing apparatus) provided with a recording medium.
1, a recording medium (CD, LD, DVD, etc.) 2302,
An operation switch 2303, a display portion (a) 2304, a display portion (b) 2305, and the like are included. The display section (a) mainly displays image information, and the display section (b) mainly displays character information. The EL display device of the present invention employs these display sections (a),
It can be used for (b). Note that the image reproducing device provided with the recording medium may include a CD reproducing device, a game machine, and the like.

FIG. 20E shows a portable computer, which includes a main body 2401, a camera section 2402, an image receiving section 2403, operation switches 2404, a display section 2405, and the like. The EL display device of the present invention can be used for the display portion 2405.

If the emission luminance of the EL material becomes higher in the future, the light including the output image information can be enlarged and projected by a lens or the like and used for a front-type or rear-type projector.

[0222] The above-mentioned electric appliances can be accessed via the Internet or C
Information distributed through an electronic communication line such as an ATV (cable television) is frequently displayed, and in particular, opportunities to display moving image information are increasing. Since the response speed of the EL material is very high, the EL display device is preferable for displaying a moving image. However, if the outline between pixels is blurred, the entire moving image is also blurred. Therefore, it is extremely effective to use the EL display device of the present invention, which makes the outline between pixels clear, as a display portion of an electric appliance.

In the EL display device, since the light emitting portion consumes power, it is desirable to display information so that the light emitting portion is reduced as much as possible. Therefore, when an EL display device is used for a portable information terminal, particularly a display portion mainly for character information such as a mobile phone or a car audio, the character information is driven by a light-emitting portion with a non-light-emitting portion as a background. It is desirable to do.

FIG. 21A shows a mobile phone, which includes a main body 2601, an audio output unit 2602, and an audio input unit 260.
3, including a display unit 2604, operation switches 2605, and an antenna 2606. The EL display device of the present invention has a display section 260.
4 can be used. Note that the display portion 2604 can display power of the mobile phone by displaying white characters on a black background.

FIG. 21B shows a car audio, which includes a main body 2701, a display portion 2702, and an operation switch 27.
03, 2704. The EL display device of the present invention can be used for the display portion 2702. In this embodiment, the in-vehicle audio is shown, but it may be used for a stationary audio. Note that the display portion 2704 can suppress power consumption by displaying white characters on a black background. This is particularly useful for audio.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electric appliances in various fields. Further, the electric appliance of this embodiment can be obtained by freely combining the configurations of Embodiments 1 to 5.

According to the information-ready EL display system of the present invention, it is possible to adjust the emission luminance of the EL display device based on the surrounding environment information and the biological information of the user obtained by a sensor such as a CCD. It is. By doing so, it is possible to suppress the emission luminance of the EL element more than necessary,
This makes it possible to suppress the deterioration of the EL element due to the flow of a large amount of current, and to provide an eye-friendly display in which the light emission luminance is suppressed in response to the abnormality of the user's eyes.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an information-enabled EL display system.

FIG. 2 illustrates a structure of an EL display device.

FIG. 3 is a diagram showing an operation of a time division gray scale method.

FIG. 4 is a diagram showing a cross-sectional structure of an EL display device.

FIG. 5 is a configuration diagram of an environment information-compatible EL display system.

FIG. 6 is an external view of an environment information-compatible EL display system.

FIG. 7 is an operation flow of an environment-information-compatible EL display system.

FIG. 8 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 9 is a top view of the entire panel of the EL display device.

FIG. 10 illustrates a manufacturing process of an EL display device.

FIG. 11 illustrates a manufacturing process of an EL display device.

FIG. 12 illustrates a manufacturing process of an EL display device.

FIG. 13 illustrates a structure of a sampling circuit of an EL display device.

FIG. 14 illustrates an appearance of an EL display device.

FIG. 15 illustrates an appearance of an EL display device.

FIG. 16 is a configuration diagram of a biological information-compatible EL display system.

FIG. 17 is an external view of a biological information compatible EL display system.

FIG. 18 is an operation flow of the biological information-compatible EL display system.

FIG. 19 illustrates a cross-sectional structure of a pixel portion of an EL display device.

FIG. 20 illustrates a specific example of an electric appliance.

FIG. 21 illustrates a specific example of an electric appliance.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05B 33/14 H05B 33/14 A

Claims (6)

[Claims] 1. A display system, wherein the light emission luminance of a light emitting device is controlled in accordance with surrounding information. 2. A light emitting device, comprising: a sensor for detecting an information signal; a CPU for converting an electric signal input from the sensor into a correction signal; and a voltage variable unit for controlling a correction potential by the correction signal. A display system characterized by the following. 3. The display system according to claim 2, wherein the light emitting device, the sensor, the CPU, and the voltage variable device are formed on a same substrate. 4. One electrode of the EL element is a current control TF.
T, and the other electrode of the EL element is
A display system, wherein a potential is controlled according to surrounding information. 5. The electric appliance according to claim 1, wherein the luminance of the light emitting device is controlled by the display system. 6. An electric appliance using the display system according to any one of claims 1 to 5.