JP2002304156A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission device capable of performing stably desired color display by suppressing the change of luminance of an OLED(organic light-emitting diodes), even when an organic light-emitting layer is degraded a slightly and an ambient temperature is changed and which has a simple configuration and has no waste in operation. SOLUTION: The value of voltage to be supplied from a variable power source to two pixel parts are corrected, so that the measured driving current becomes a reference value by measuring drive current of the pixel part. At measuring the drive current of the OLED, an image for monitoring is made to be displayed on the pixel part by using a video signal for monitoring whose system is different from that of a video signal for displaying an image. By the constitution, the lowering of luminance accompanied by the deterioration of the organic light-emitting layer can be suppressed, and as a result, a sharp image can be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device (OLED) formed on a substrate.
evice) is enclosed between the substrate and the cover material.
About the panel. Further, the present invention relates to an OLED module in which a controller IC or the like is mounted on the OLED panel. In this specification, the OLED panel and the OLED module are collectively referred to as a light emitting device. The invention further relates to an electronic device using the light emitting device.

[0002]

2. Description of the Related Art An OLED emits light by itself and has high visibility, and does not require a backlight necessary for a liquid crystal display device (LCD). Therefore, the OLED is suitable for thinning and has no restriction on a viewing angle. Therefore, in recent years, light emitting devices using OLED
It is attracting attention as a display device replacing T and LCD.

[0003] An OLED has a layer containing an organic compound (organic light emitting material) capable of obtaining luminescence (Electroluminescence) generated by applying an electric field (hereinafter, referred to as an organic light emitting layer), an anode layer, and a cathode layer. are doing. Luminescence of an organic compound 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. Either one of the above-described light emissions may be used, or both light emissions may be used.

[0004] In this specification, all layers provided between the anode and cathode of an OLED are defined as organic light-emitting layers.
The organic light emitting layer specifically includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, an OLED has a structure in which an anode / light-emitting layer / cathode is laminated in this order. In addition to this structure, an anode / hole injection layer /
It may have a structure in which a light emitting layer / cathode or an anode / hole injection layer / light emitting layer / electron transport layer / cathode are stacked in this order.

[0005]

One of the serious problems at present in putting a light emitting device into practical use is a decrease in luminance of an OLED due to deterioration of an organic light emitting material of an organic light emitting layer. is there.

The organic light emitting material of the organic light emitting layer is water,
It is susceptible to oxygen, light and heat, and accelerates deterioration by these substances. Specifically, the rate of deterioration of the organic light-emitting layer depends on the structure of the device for driving the light-emitting device, the characteristics of the organic light-emitting material constituting the organic light-emitting layer, the material of the electrode, the conditions in the manufacturing process, the driving method of the light-emitting device, and the like. Is affected.

Even when a constant voltage is applied to the organic light emitting layer from a pair of electrodes, the organic light emitting layer is
Brightness decreases. Then, when the luminance of the OLED decreases, the image displayed on the light emitting device becomes unclear. In this specification, a voltage applied from a pair of electrodes to an organic light emitting layer is defined as an OLED drive voltage (Vel).

In a color display system using three types of OLEDs corresponding to R (red), G (green) and B (blue), the organic light emitting material constituting the organic light emitting layer is OLED
Depends on the corresponding color. Thus, the organic light emitting layer of the OLED may degrade at different rates for each corresponding color. In this case, as the time elapses, the luminance of the OLED differs for each color, and an image having a desired color cannot be displayed on the light emitting device.

Further, since the light emission luminance of the OLED has a large temperature dependency, there is a problem that the display luminance and the color tone change depending on the temperature when driven at a constant voltage.

[0010] In view of the above, the present invention has been developed in view of the fact that even if the organic light emitting layer is slightly degraded or the environmental temperature changes, the OL
It is an object to provide a light emitting device capable of suppressing a change in the luminance of an ED and stably performing a desired color display.

[0011]

SUMMARY OF THE INVENTION The inventor of the present invention considers that the OLED driving voltage is kept constant and the OLED is driven while the current flowing through the OLED is kept constant. First, attention was paid to the fact that the decrease in luminance was small. In this specification, the current flowing through the OLED is called an OLED drive current (Iel).

FIG. 2 shows the OLED when the OLED drive voltage is fixed and when the OLED drive current is fixed.
5 shows a change in luminance of the image. As shown in FIG. 2, the OLED having a constant OLED drive current has a smaller change in luminance due to deterioration. This is because when the OLED is deteriorated, not only does the slope of the LI line decrease, but also the IV curve itself moves downward. (FIGS. 18A and 18B)
reference)

Therefore, the present inventor has determined that OLE
We have devised a light emitting device that can correct the OLED drive voltage so that the OLED drive current is always constant even when the D drive current changes.

Specifically, in the light emitting device of the present invention, the O
First means for measuring the OLED drive current of the LED, and second means for calculating a voltage to be applied to the OLED from the measured value
Means, and third means for actually controlling the voltage value.

The second means is for comparing the measured current value with the reference value, and the third means is for reducing the difference between the measured value and the reference value when there is a certain difference. The OLED of the display pixel (hereinafter, the display OLED or the first OLED) and the monitor OLE
Means for correcting the D OLED drive voltage may be used.

In this specification, a variable power supply means a power supply in which a voltage supplied to a circuit or an element is not constant but variable.

When measuring the OLED drive current of the OLED in the pixel portion, a monitor image is displayed on the pixel portion by a monitor video signal (hereinafter, referred to as a monitor video signal). However, both video signals are the same in that they contain gradation information,
The displayed image systems are merely different. The monitor image may be a still image or a moving image. Also, the same gradation may be displayed in all pixels.

The reference values of the current need not always be set to the same value. Monitor images having different reference current values may be prepared, and the monitor image may be selected each time monitoring is performed. Of course, several types of monitor images having the same reference current value may be prepared.

With the above configuration, the light emitting device of the present invention has
Even if the organic light emitting layer is deteriorated, a decrease in the luminance of the OLED can be suppressed, and as a result, a clear image can be displayed.

In the case of a color display system using three types of OLEDs corresponding to R (red), G (green), and B (blue), the OLED drive current is measured for each OLED of each color.
The OLED drive voltage may be corrected. With this configuration, even if the organic light emitting layer of the OLED deteriorates at a different speed for each corresponding color, it is possible to display a desired color while preventing the luminance balance of each color from being lost.

Further, the temperature of the organic light emitting layer is determined by the outside air temperature and OL temperature.
Although it depends on the heat generated by the ED panel itself, the value of the current flowing varies depending on the temperature when the OLED is driven at a constant voltage. FIG. 3 shows a change in the voltage-current characteristics of the OLED when the temperature of the organic light emitting layer is changed. When the temperature of the organic light emitting layer increases when the voltage is constant, OLE
The D drive current increases. And OLED drive current and O
Since the brightness of the LED is almost proportional, the larger the OLED drive current, the higher the brightness of the OLED. In FIG. 2, the reason why the constant voltage luminance shows a vertical cycle of about 24 hours is that the day / night temperature difference is reflected. However, in the light emitting device of the present invention, even when the temperature of the organic light emitting layer changes, the OLED drive voltage is corrected to correct the OLED driving voltage.
The LED drive current can always be kept constant. Therefore, a constant luminance can be obtained without being affected by a temperature change, and power consumption can be prevented from increasing with an increase in temperature.

Further, in general, the degree of change of the OLED drive current in the temperature change varies depending on the type of the organic light emitting material. Therefore, in the color display, the luminance of the OLED of each color may vary depending on the temperature. However, in the light emitting device of the present invention, a constant luminance can be obtained without being affected by a change in temperature. Therefore, it is possible to prevent the luminance balance of each color from being lost and to display a desired color.

Although the present invention is particularly effective for an active matrix light emitting device driven by digital time gray scale, it is also effective for an active matrix light emitting device driven by analog gray scale. Further, it can be used for a passive light emitting device.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below.

FIG. 1 shows the structure of the OLED panel of the present invention.
Shown in block diagram. Reference numeral 101 denotes a pixel portion, and a plurality of pixels 102 are formed in a matrix. 103 is a source line drive circuit, and 104 is a gate line drive circuit.

In FIG. 1, the source line driving circuit 103 and the gate line driving circuit 104 are formed on the same substrate as the pixel portion 101; however, the present invention is not limited to this structure. Source line drive circuit 103 and gate line drive circuit 10
4 are formed on a different substrate from the pixel portion 101, and the FPC
May be connected to the pixel unit 101 via a connector such as. Although one source line driver circuit 103 and one gate line driver circuit 104 are provided in FIG. 1, the present invention is not limited to this structure. Source line drive circuit 10
3 and the number of gate line drive circuits 104 can be arbitrarily set by a designer.

In FIG. 1, the source line S
1 to Sx, power supply lines V1 to Vx, and gate lines G1 to Gy are provided. Note that the numbers of source lines and power supply lines are not always the same. In addition to these wirings, another different wiring may be provided.

Each pixel 102 has an OLED 105. OLED 105 has an anode and a cathode,
In this specification, the cathode is called a counter electrode (second electrode) when the anode is used as a pixel electrode (first electrode), and the anode is called a counter electrode when the cathode is used as a pixel electrode.

The pixel electrodes of the OLED 105 of each pixel 102 are connected to power supply lines V1 to Vx via one or a plurality of TFTs.
Is connected to any one of. And power supply lines V1 to
All Vx are connected to the variable power supply 106 via the ammeter 107. Further, all the opposing electrodes of the OLED 105 are connected to the variable power supply 106. OLED10
The five counter electrodes may be connected to the variable power supply 106 via one or more elements.

In this specification, a variable power supply means a power supply whose voltage supplied to circuits and elements is variable. In FIG. 1, the variable power supply 106 has a high potential (Vd
In d), the connection is made such that the opposite electrode side is kept at a low potential (Vss). However, the present invention is not limited to this configuration, and the variable power supply 106 may be connected so that the current flowing through the OLED 105 becomes forward biased.

In FIG. 1, all the power supply lines V1 to Vx are connected in series to the ammeter 107.
Vx is supplied to the variable power source 106 via the ammeter 107.
And the remaining power supply line may be connected to the variable power supply 106 without passing through the ammeter 107.

The position where the ammeter 107 is provided does not necessarily need to be between the variable power supply 106 and the power supply line, but may be between the variable power supply 106 and the counter electrode.

Reference numeral 108 denotes a correction circuit, and the ammeter 1
07 from the variable power supply 106 to the common electrode and power supply lines V1 to Vx based on the current value (measurement value) measured at 07.
To control the voltage supplied to the

The ammeter 107, the variable power supply 106, and the correction circuit 108 are formed on a substrate different from the substrate on which the pixel portion 101 is formed, and are connected to the pixel portion 101 via a connector or the like. Alternatively, as long as fabrication is possible, the pixel portion 101 may be formed over the same substrate.

In the case of the color display method, a variable power supply and an ammeter are provided for each color, and the OLED of each color is OL.
The ED drive voltage may be corrected. At this time, the correction circuit may be provided for each color, or the OL
A common correction circuit may be provided for the ED.

FIG. 4 shows a detailed configuration of each pixel. The pixel shown in FIG. 4 includes a source line Si (i = 1 to x), a gate line Gj (j = 1 to y), a power supply line Vi, and a switching TF.
It includes a T110, a driving TFT 111, a capacitor 112, and an OLED 105. Note that the configuration of the pixel illustrated in FIG. 4 is merely an example, and the number, type, and connection of wirings and elements included in the pixel are not limited to the configuration illustrated in FIG. The light emitting device of the present invention may have any configuration as long as the OLED drive voltage of the OLED of each pixel can be controlled by the variable power supply 106.

In FIG. 4, the gate electrode of the switching TFT 110 is connected to the gate line Gj. One of the source region and the drain region of the switching TFT 110 is connected to the source line Si, and the other is connected to the driving TFT 1.
11 gate electrodes. And the driving T
One of the source region and the drain region of the FT 111 is connected to the power supply line Vi, and the other is connected to the pixel electrode of the OLED 105. The capacitor 112 is formed between the gate electrode of the driving TFT 111 and the power supply line Vi.

In the pixel shown in FIG. 4, the potential of the gate line Gj is controlled by the gate line driving circuit 104, and a video signal or a monitor video signal is input to the source line Si by the source line driving circuit 103. When the switching TFT 110 is turned on, the video signal or the monitoring video signal input to the source line Si is input to the gate electrode of the driving TFT 111 via the switching TFT 110. When the driving TFT 111 is turned on by the video signal or the monitoring video signal, the OLED driving voltage is applied between the pixel electrode and the opposing electrode of the OLED 105 by the variable power supply 106, and the OLE is driven.
D105 emits light.

When the OLED 105 emits light, a current is measured by the ammeter 107, and the measured value is sent to the correction circuit 108 as data. The period during which the current is measured depends on the performance of the ammeter 107, and needs to be longer than the measurable length. In addition, the ammeter 107
Then, the average value or the maximum value of the current flowing during the measurement period is read.

The correction circuit 108 compares the measured current value with a predetermined current value (reference value). And
When there is a certain difference between the measured value and the reference value, the correction circuit 108 controls the variable power supply 106 to control the power supply lines V1 to V
Correct the voltage between x and the counter electrode. Thereby, the OLED drive voltage is corrected in the OLED of each pixel 102, and an OLED drive current of a desired magnitude flows.

The OLED drive voltage may be corrected by controlling the potential on the power supply line side, or may be corrected by controlling the potential on the counter electrode side.
The correction may be performed by controlling both the potential on the power supply line side and the potential on the counter electrode side.

FIG. 5 shows the OLE of each color OLED when controlling the potential on the power supply line side in the color light emitting device.
5 shows a change in D drive voltage. In FIG. 5, Vr is O for R
OLED drive voltage before correction in the LED, Vr
₀ is the OLED drive voltage after correction. Similarly, Vg is the OLED drive voltage before correction in the G OLED, and Vg ₀ is the OLED drive voltage after correction. Vb is the OLED drive voltage before correction in the OLED for B, and Vb ₀ is the OLED drive voltage after correction.

In the case of FIG. 5, the potential of the counter electrode (counter potential)
Is fixed at the same height in all OLEDs.
The OLED drive current is measured for each OLED of each color, and the OLED drive voltage is corrected by controlling the potential of the power supply line (power supply potential) with a variable power supply.

According to the light emitting device of the present invention,
The same change in luminance as when the OLED drive current in FIG. 2 is constant is obtained.

According to the present invention, a decrease in the luminance of the OLED can be suppressed even if the organic light-emitting layer is deteriorated by the above structure.
As a result, a clear image can be displayed. Further, in the case of a light emitting device for color display using OLED corresponding to each color, even if the organic light emitting layer of the OLED deteriorates at a different speed for each corresponding color, it is possible to prevent the luminance balance of each color from being lost. Can display a desired color.

Further, the temperature of the organic light emitting layer is determined by the outside air temperature and OL temperature.
Even if it is affected by the heat generated by the ED panel itself, the OLED
Can be suppressed from changing, and the power consumption can be prevented from increasing with an increase in temperature. In the case of a color display light-emitting device, a change in luminance of each color OLED can be suppressed without being affected by a change in temperature, so that the balance of luminance of each color can be prevented from being lost and a desired color can be displayed. can do.

[0047]

Embodiments of the present invention will be described below.

Embodiment 1 In this embodiment, a detailed configuration of a correction circuit included in the light emitting device of the present invention will be described.

FIG. 6 is a block diagram showing the configuration of the correction circuit of this embodiment. The correction circuit 203 includes the A / D conversion circuit 20
4. It has a measurement value memory 205, an arithmetic circuit 206, a reference value memory 207, and a controller 208.

The current value (measured value) measured by the ammeter 201 is input to the A / D conversion circuit 204 of the correction circuit 203. In the A / D conversion circuit 204,
Analog measurements are converted to digital. The converted digital data of the measured value is input to and held in the measured value memory 205.

On the other hand, the reference value memory 207 holds digital data of a measured value of an ideal value, that is, a so-called reference value. In the arithmetic circuit 206, the measured value memory 20
5. the digital data of the measured values held in 5,
The reference value digital data held in the reference value memory 207 is read out and compared.

By comparing the digital data of the measured value and the digital data of the reference value, the variable power supply 202 is controlled to control the power supply line V1 in order to make the value of the current actually flowing through the ammeter 201 close to the reference value. The voltage between Vx and the counter electrode is corrected. Thereby, the OLE that each pixel has
At D, the OLED drive voltage is corrected, and an OLED drive current of a desired magnitude flows.

Assuming that the difference between the current of the measured value and the reference value is the deviation current, and that the voltage between the power supply lines V1 to Vx and the counter electrode that is changed by the correction is the correction voltage, the relationship between the deviation current and the correction voltage is as follows. , For example, as shown in FIG. In FIG. 7, the correction voltage is changed by a constant value each time the deviation current changes by a certain width.

Note that the relationship between the deviation current and the correction voltage does not necessarily have to conform to the graph shown in FIG. The deviation current and the correction voltage need only be in a relationship such that the value of the current actually flowing through the ammeter approaches the reference value. For example, the deviation current and the correction voltage may have a linear relationship,
The deviation current may be proportional to the square of the correction voltage.

The configuration of the correction circuit shown in this embodiment is merely an example, and the present invention is not limited to this configuration. The correction circuit used in the present invention has a means for comparing a measured value with a reference value, and a means for performing some kind of arithmetic processing based on a value measured by an ammeter to correct an OLED drive voltage. good. Instead of performing the correction using the current reference value stored in the memory, it is only necessary to prescribe the calculation processing method when the deviation current exceeds a certain value.

(Embodiment 2) In this embodiment, a structure of a pixel of the light emitting device of the present invention which is different from that of FIG. 4 will be described.

FIG. 8 shows a configuration of a pixel according to this embodiment. In the pixel portion of the light emitting device of this embodiment, pixels 300 are provided in a matrix. The pixel 300 includes a source line 301,
First gate line 302, second gate line 303, power supply line 30
4. Switching TFT 305, driving TFT 30
6, an erasing TFT 309 and an OLED 307.

The gate electrode of the switching TFT 305 is connected to the first gate line 302. One of the source region and the drain region of the switching TFT 305 is connected to the source line 301, and the other is connected to the driving TFT.
306 is connected to the gate electrode.

The gate electrode of the erasing TFT 309 is connected to the second gate line 303. One of a source region and a drain region of the erasing TFT 309 is connected to the power supply line 304,
The other is connected to the gate electrode of the driving TFT 306.

The source region of the driving TFT 306 is connected to the power supply line 304, and the drain region is connected to the pixel electrode of the OLED 307. The capacitor 308 is a driving TFT 30
6 between the gate electrode 6 and the power supply line 304.

The power supply line 304 is connected to a variable power supply 311 via an ammeter 310. In addition, OLED 307
Are connected to the variable power supply 311. In FIG. 8, the variable power supply 311 has a high potential (Vd
In d), the connection is made such that the opposite electrode side is kept at a low potential (Vss). However, the present invention is not limited to this configuration, and the variable power supply 311 may be connected so that the current flowing through the OLED 307 becomes forward biased.

The position where the ammeter 310 is provided does not necessarily need to be between the variable power supply 311 and the power supply line 304, but may be between the variable power supply 311 and the counter electrode.

Reference numeral 312 denotes a correction circuit.
The voltage supplied from the variable power supply 311 to the common electrode and the power supply line 304 is controlled based on the current value (measured value) measured in 10.

Note that the ammeter 310, the variable power supply 311, and the correction circuit 312 may be formed on a substrate different from the substrate on which the pixel portion is formed, and may be connected to the pixel portion via a connector or the like. Alternatively, they may be formed on the same substrate as the pixel portion if fabrication is possible.

In the case of the color display method, a variable power supply and an ammeter are provided for each color, and the OLED of each color is OL.
The ED drive voltage may be corrected. At this time, the correction circuit may be provided for each color, or the OL
A common correction circuit may be provided for the ED.

In the pixel shown in FIG. 8, the first gate line 30
The potentials of the second and second gate lines 303 are controlled by different gate line driving circuits. A video signal or a monitor video signal is input to the source line 301 by a source line driver circuit.

When the switching TFT 305 is turned on, the video signal or the monitor video signal input to the source line 301 is input to the gate electrode of the driving TFT 306 via the switching TFT 301. Then, when the driving TFT 306 is turned on by the video signal or the video signal for monitoring, the OLED driving voltage is applied between the pixel electrode and the opposing electrode of the OLED 307 by the variable power supply 311 and the OLED 307 emits light.

When the erasing TFT 309 is turned on, the potential difference between the source region and the gate electrode of the driving TFT 306 becomes close to 0, and the driving TFT 306 is turned off. Therefore, the OLED 307 does not emit light.

In the present invention, when the OLED 307 emits light, the current is measured by the ammeter 310, and the measured value is sent to the correction circuit 312 as data.

In the correction circuit 312, the measured value of the current is compared with a predetermined current value (reference value). And
When there is a certain difference between the measured value and the reference value, the variable power supply 311 is controlled to correct the voltage between the power supply line 304 and the counter electrode. As a result, O
The OLED drive voltage is corrected in the LED 307, and a desired OLED drive current flows.

The OLED drive voltage may be corrected by controlling the potential on the power supply line side, or may be corrected by controlling the potential on the counter electrode side.
The correction may be performed by controlling both the potential on the power supply line side and the potential on the counter electrode side.

The configuration of the pixel shown in this embodiment is merely an example, and the present invention is not limited to this configuration. Note that this embodiment can be implemented by being freely combined with the first embodiment.

(Embodiment 3) In this embodiment, a monitor image displayed on a pixel portion when current correction is performed in the light emitting device of the present invention will be described.

In the present invention, the correction may be performed at a time determined in advance by setting, or the correction time may be arbitrarily determined by the user each time.

When the correction is performed at a predetermined time according to the setting, it is preferable from the viewpoint of convenience that the displayed image does not change against the intention of the user. For example, a mobile phone can be set so that correction is performed only when a standby image is displayed, or a personal computer (PC) is activated when a screen saver for preventing screen burn-in is activated. It is set so that only correction is performed. By storing the reference value of the current when each screen is displayed in the correction circuit, the correction can be performed so that the displayed screen does not change against the intention of the user.

Further, the image displayed at the time of performing the correction may be used as it is as a monitor image, and monitor images having different reference current values may be used. In this case, the video signal is also input to the correction circuit, and a reference value is calculated by an arithmetic circuit or the like. If you do not use monitor images, you do not need to use monitor video signals.
Of course, the displayed image does not change against the intention of the user.

This embodiment can be implemented by freely combining with Embodiments 1 and 2.

(Embodiment 4) In this embodiment, FIGS.
The driving method of the light emitting device of the present invention shown in FIG. In FIG. 9, the horizontal axis represents time, and the vertical axis represents the position of a pixel connected to each gate line.

First, when the writing period Ta starts,
The power supply potentials of the power supply lines V1 to Vx are maintained at the same height as the potential of the counter electrode of the OLED 105. Then, according to the selection signal output from the gate line driving circuit 104, all pixels (pixels on the first line) connected to the gate line G1
Of the switching TFT 110 is turned on.

Then, the first bit digital video signal (hereinafter referred to as digital video signal) input to the source lines (S1 to Sx) by the source line driving circuit 103
Is the driving TFT via the switching TFT 110
Input to the gate electrode 111.

Next, the switching T of the pixel on the first line
The FT 110 is turned off, and like the pixel on the first line,
The switching TFT 110 of the pixel on the second line connected to the gate line G2 is turned on by the selection signal. Next, the first bit digital video signal is input from the source lines (S1 to Sx) to the gate electrode of the driving TFT 111 via the switching TFT 110 of the pixel on the second line.

Then, the digital video signal of the first bit is sequentially input to the pixels of all the lines. A period until the digital video signal of the first bit is input to the pixels of all lines is a writing period Ta1. In the present embodiment, the input of the digital video signal to the pixel means that
This means that a digital video signal is input to the gate electrode of the driving TFT 111 via the switching TFT 110.

When the writing period Ta1 ends, the display period Tr1 starts next. In the display period Tr1, the power supply potential of the power supply line becomes a potential having a potential difference between the power supply line and the counter electrode to such an extent that the OLED emits light when the power supply potential is applied to the pixel electrode of the OLED.

In this embodiment, when the digital video signal has information of “0”, the driving TFT 111
Is turned off. Therefore, the power supply potential is
5 is not provided to the pixel electrode. As a result, the OLED 105 included in the pixel to which the digital video signal having the information “0” is input does not emit light.

Conversely, when the information has “1”, the driving TFT 111 is in an ON state. Therefore, the power supply potential is applied to the pixel electrode of the OLED 105. As a result, the OLED 105 included in the pixel to which the digital video signal having the information “1” is input emits light.

As described above, in the display period Tr1, OL is not applied.
The ED 105 emits light or emits no light, and all the pixels perform display. A period during which the pixel performs display is called a display period Tr. In particular, a display period started when the first bit digital video signal is input to the pixel is referred to as Tr1.

When the display period Tr1 ends, the writing period Ta
The power supply potential of the power supply line becomes the same as the potential of the opposing electrode of the OLED again. Then, all the gate lines are sequentially selected as in the case of the writing period Ta1, and the digital video signal of the second bit is input to all the pixels. A period until the digital video signal of the second bit is completely input to the pixels of all lines is referred to as a writing period Ta2.

When the writing period Ta2 ends, the display period Tr
The power supply potential of the power supply line becomes a potential having a potential difference between the power supply line and the counter electrode to such an extent that the OLED emits light when the power supply potential is applied to the pixel electrode of the OLED. Then, all the pixels perform display.

The above operation is repeated until the n-th bit digital video signal is input to the pixel, and the writing period Ta and the display period Tr appear repeatedly. When all the display periods (Tr1 to Trn) end, one image can be displayed. In the specification, a period during which one image is displayed is referred to as one frame period (F). When one frame period ends, the next frame period starts. Then, the writing period Ta1 appears again, and the above operation is repeated.

In a normal light emitting device, it is preferable to provide 60 or more frame periods per second. When the number of images displayed in one second is less than 60, flickering of the images may start to be noticeable.

In this embodiment, the sum of the lengths of all the writing periods is shorter than one frame period, and the length ratio of the display periods is Tr1: Tr2: Tr3:...: Tr (n−
1): Trn = 2 ⁰ : 2 ¹ : 2 ² : ...: 2 ^(n-2) : 2 ^(n-1)
It is necessary that A desired gradation display out of 2 ⁿ gradations can be performed by the combination of the display periods.

By calculating the sum of the lengths of the display periods in which the OLED emits light during one frame period, the displayed gradation of the pixel in the frame period is determined. For example, if n = 8 and the luminance when the pixel emits light in all display periods is 100%, when the pixel emits light in Tr1 and Tr2, 1% luminance can be expressed.
When Tr5 and Tr8 are selected, 60% luminance can be expressed.

The display periods Tr1 to Trn may appear in any order. For example, during one frame period, the display periods can appear in the order of Tr1, Tr5, Tr2,... Next to Tr1.

In the present embodiment, the height of the power supply potential of the power supply line is changed between the writing period and the display period, but the present invention is not limited to this. The power supply potential and the potential of the counter electrode may always have a potential difference such that the OLED emits light when the power supply potential is applied to the pixel electrode of the OLED. In that case, the OLED can emit light even during the writing period. Therefore, the gray scale displayed by the pixel in the frame period is O in one frame period.
It is determined by the sum of the lengths of the writing period and the display period during which the LED emits light. In this case, the ratio of the sum of the lengths of the writing period and the display period corresponding to the digital video signal of each bit is
(Ta1 + Tr1): (Ta2 + Tr2): (Ta3 +
Tr3): ...: (Ta (n-1) + Tr (n-1)):
^{(Tan + Trn) = 2 0} : 2 1: 2 2: ...: 2 (n-2): 2
It is necessary to be ^(n-1) .

The driving method described in this embodiment is only an example, and the driving method of the light emitting device of the present invention shown in FIGS. 1 and 4 is not limited to the driving method of this embodiment. The light emitting device of the present invention shown in FIGS. 1 and 4 can also perform display by an analog video signal.

This embodiment can be implemented by freely combining with Embodiments 1 and 3.

Embodiment 5 In this embodiment, a detailed configuration of a source line driving circuit and a gate line driving circuit used for driving a pixel portion of a light emitting device of the present invention will be described.

FIG. 10 is a block diagram showing a driving circuit of the light emitting device of this embodiment. FIG. 10A illustrates a source line driver circuit 601, a shift register 602, a latch (A) 6
03, a latch (B) 604.

In the source line driver circuit 601, a clock signal (CLK) and a start pulse (SP) are input to the shift register 602. Shift register 602
Generates a timing signal sequentially based on the clock signal (CLK) and the start pulse (SP),
A timing signal is sequentially input to a subsequent circuit through a buffer or the like (not shown).

The timing signal from the shift register 602 is buffer-amplified by a buffer or the like. The wiring to which the timing signal is input has a large load capacitance (parasitic capacitance) because many circuits or elements are connected.
This buffer is provided to prevent "dulling" of the rise or fall of the timing signal caused by the large load capacitance. It is not always necessary to provide a buffer.

The timing signal buffer-amplified by the buffer is input to the latch (A) 603. The latch (A) 603 has a plurality of stages of latches for processing digital video signals. Latch (A) 603
When the timing signal is input, digital video signals input from outside the source line driving circuit 601 are sequentially written and held.

When a digital video signal is written to the latch (A) 603, the digital video signal may be sequentially written to a plurality of stages of latches of the latch (A) 603. However, the present invention is not limited to this configuration. A plurality of stages of latches of the latch (A) 603 are divided into several groups, and a digital video signal is simultaneously written in each group in parallel.
So-called split driving may be performed. The number of groups at this time is called a division number. For example, when the latch is divided into groups for every four stages, it is referred to as divided drive in four divisions.

The time until the writing of the digital video signal to the latches of all the stages of the latch (A) 603 is completed is called a line period. Actually, the line period may include a period obtained by adding the horizontal retrace period to the line period.

When one line period ends, the latch (B)
A latch signal (Latch Signal) is input to 604. At this moment, the digital video signal written and held in the latch (A) 603 is simultaneously sent to the latch (B) 604, and written and held in the latches of all the stages of the latch (B) 604.

The digital video signal is latched (B) 604
The digital video signal is sequentially written into the latch (A) 603 which has been transmitted to the latch 603 based on the timing signal from the shift register 602.

During the second one line period, the digital video signal written and held in the latch (B) 604 is input to the source line.

FIG. 10B is a block diagram showing a configuration of the gate line driving circuit.

The gate line driving circuit 605 has a shift register 606 and a buffer 607, respectively. In some cases, a level shift may be provided.

In the gate line driving circuit 605, the timing signal from the shift register 606 is
To the corresponding gate line. The gate line is connected to a gate electrode of a TFT included in one line of pixels. Since the TFTs of the pixels for one line must be turned on all at once, a buffer capable of flowing a large current is used.

The driving circuit shown in this embodiment is only one example. This embodiment can be implemented by freely combining with Embodiments 1 to 4.

Embodiment 6 In this embodiment, the appearance of a light emitting device of the present invention will be described with reference to FIG.

FIG. 11A is a top view of the light emitting device, FIG. 11B is a cross-sectional view taken along line AA ′ of FIG. 11A, and FIG. 11C is FIG. 13 is a sectional view taken along line BB ′ of FIG.

A pixel portion 400 provided on a substrate 4001
2, a sealing material 4009 is provided so as to surround the source line driving circuit 4003 and the first and second gate line driving circuits 4004a and 4004b. The pixel portion 4002
Sealing material 40 on the source line driving circuit 4003 and the first and second gate line driving circuits 4004a and 4004b.
08 is provided. Therefore, the pixel portion 4002, the source line driver circuit 4003, and the first and second gate line driver circuits 4004a and 4004b
09 and the sealing material 4008, the filler 421
Sealed with 0.

The pixel portion 4 provided on the substrate 4001
002, the source line driving circuit 4003, and the first and second
Gate line drive circuits 4004a and 4004b are a plurality of TFTs
have. In FIG. 11B, typically, the base film 40 is formed.
The TFT for driving circuit included in the source line driving circuit 4003 (here, an n-channel TFT
An FT and a p-channel TFT 4201 are shown) and a driving TFT (TFT controlling a current to an OLED) 4202 included in the pixel portion 4002 is shown.

In this embodiment, the driving circuit TFT 4201 is used.
A p-channel TFT or an n-channel TFT manufactured by a known method is used for the driving TFT 4202.
A p-channel TFT manufactured by a known method is used. Further, a driving TFT 420 is provided in the pixel portion 4002.
A storage capacitor (not shown) connected to the second gate electrode is provided.

Driving Circuit TFT 4201 and Driving TF
An interlayer insulating film (flattening film) 4301 is formed over T4202, and a pixel electrode (anode) 4203 electrically connected to the drain of the driving TFT 4202 is formed thereon. As the pixel electrode 4203, a transparent conductive film having a large work function is used. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Further, a material obtained by adding gallium to the transparent conductive film may be used.

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

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

On the organic light emitting layer 4204, a cathode 4205 made of a light-shielding conductive film (typically, a conductive film containing aluminum, copper, or silver as a main component or a laminated film of these and another conductive film). Is formed. The cathode 4
It is desirable that moisture and oxygen existing at the interface between 205 and the organic light emitting layer 4204 be eliminated as much as possible. Therefore, it is necessary to devise a method in which the organic light emitting layer 4204 is formed in a nitrogen or rare gas atmosphere, and the cathode 4205 is formed without being exposed to oxygen or moisture. In this embodiment, the above-described film formation is made possible by using a multi-chamber type (cluster tool type) film formation apparatus. And the cathode 4205
Is given a predetermined voltage.

As described above, the pixel electrode (anode) 42
03, O composed of an organic light emitting layer 4204 and a cathode 4205
An LED 4303 is formed. And OLED4303
A protective film 4209 is formed over the insulating film 4302 so as to cover. The protective film 4209 is effective for preventing oxygen, moisture, and the like from entering the OLED 4303.

A wiring 4005a is connected to a power supply line and is electrically connected to the source region of the driving TFT 4202. The lead wiring 4005a passes between the sealant 4009 and the substrate 4001 and passes through the anisotropic conductive film 4300 to the FPC 4006.
Is electrically connected to the wiring for wiring 4301.

As the sealing material 4008, a glass material, a metal material (typically, a stainless steel material), a ceramic material, and a plastic material (including a plastic film) can be used. FRP as plastic material
(Fiberglass-Reinforced Pl
aics) plate, PVF (polyvinyl fluoride)
A film, a mylar film, a polyester film, or an acrylic resin film can be used. Further, a sheet having a structure in which an aluminum foil is sandwiched between PVF films or mylar films can also be used.

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

As the filler 4103, besides an inert gas such as nitrogen or argon, an ultraviolet curable resin or a thermosetting resin can be used, such as PVC (polyvinyl chloride), acrylic, polyimide, epoxy resin, silicone resin. Resin, PVB (polyvinyl butyral) or E
VA (ethylene vinyl acetate) can be used. In this embodiment, nitrogen was used as the filler.

Further, in order to expose the filler 4103 to a hygroscopic substance (preferably barium oxide) or a substance capable of adsorbing oxygen, the substrate 400
A concave portion 4007 is provided on the one surface, and a hygroscopic substance or a substance 4207 capable of adsorbing oxygen is arranged. Then, the hygroscopic substance or the substance 4207 capable of adsorbing oxygen is held in the concave part 4007 by the concave part cover material 4208 so that the hygroscopic substance or the substance 4207 capable of adsorbing oxygen is not scattered. Note that the concave portion cover member 4208 has a fine mesh shape, and has a configuration in which air and moisture are allowed to pass, and a hygroscopic substance or a substance 4207 capable of adsorbing oxygen is not allowed to pass. By providing the hygroscopic substance or the substance 4207 which can adsorb oxygen, deterioration of the OLED 4303 can be suppressed.

As shown in FIG. 11C, the pixel electrode 42
Simultaneously with the formation of 03, a conductive film 4203a is formed so as to be in contact with the lead wiring 4005a.

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

The ammeter, variable power supply, and correction circuit of the light emitting device of the present invention are formed on a substrate (not shown) different from the substrate 4001, and formed on the substrate 4001 via the FPC 4006. The power supply line and the cathode 4205 are electrically connected.

Note that this embodiment can be implemented by freely combining with Embodiments 1 to 5.

Embodiment 7 In this embodiment, an ammeter, a variable power supply, and a correction circuit of the light emitting device of the present invention are formed on a substrate different from the substrate on which the pixel portion is formed, and wire bonding is performed. An example of connection with a wiring on a substrate on which a pixel portion is formed by a method such as a method and a COG (chip-on-glass) method will be described.

FIG. 12 is an external view of the light emitting device of this embodiment. The sealing member 5 is provided so as to surround the pixel portion 5002 provided over the substrate 5001, the source line driver circuit 5003, and the first and second gate line driver circuits 5004a and 5004b.
009 is provided. A sealing material 5008 is provided over the pixel portion 5002, the source line driver circuit 5003, and the first and second gate line driver circuits 5004a and 5004b. Accordingly, the pixel portion 5002, the source line driving circuit 5003, and the first and second gate line driving circuits 50
04a and 04b are sealed together with a filler (not shown) by a substrate 5001, a sealing material 5009, and a sealing material 5008.

A concave portion 5007 is provided on the surface of the sealing material 5008 on the substrate 5001 side, and a hygroscopic substance or a substance capable of adsorbing oxygen is arranged.

The wiring routed on the substrate 5001 (routing wiring) is composed of the sealing material 5009 and the substrate 5001.
And is connected to a circuit or element external to the light emitting device via the FPC 5006.

An ammeter, a variable power supply, and a correction circuit included in the light emitting device of the present invention are formed on a substrate (hereinafter, referred to as a chip) 5020 different from the substrate 5001, and a COG (chip-on-glass) method or the like is used. And is electrically connected to a power supply line and a cathode (not shown) formed on the substrate 5001.

In this embodiment, a chip 5020 on which an ammeter, a variable power supply, and a correction circuit are formed is mounted on a substrate 5001 by a wire bonding method, a COG method, or the like, so that the light-emitting device can be a single substrate. Can be configured,
The device itself becomes compact and the mechanical strength increases.

It is to be noted that a method of connecting a chip on a substrate can be performed by using a known method. Further, circuits and elements other than the ammeter, the variable power supply, and the correction circuit may be mounted on the substrate 5001.

This embodiment can be implemented by freely combining with Embodiments 1 to 6.

(Embodiment 8) In the present invention, by using an organic light emitting material capable of utilizing phosphorescence from triplet excitons for light emission, external light emission quantum efficiency can be remarkably improved. Thereby, low power consumption, long life, and light weight of the OLED can be achieved.

Here, there is a report that the triplet exciton is used to improve the external light emission quantum efficiency. (T.Tsutsui, C.Adac
hi, S. Saito, Photochemical Processes in Organized
Molecular Systems, ed.K. Honda, (Elsevier Sci. Pub.,
Tokyo, 1991) p.437.)

The molecular formula of the organic luminescent material (coumarin dye) reported in the above-mentioned article is shown below.

[0141]

Embedded image

(MABaldo, DFO'Brien, Y. You, A. Shou
stikov, S. Sibley, METhompson, SRForrest, Nature
395 (1998) p.151.)

The molecular formula of the organic luminescent material (Pt complex) reported in the above-mentioned article is shown below.

[0144]

Embedded image

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

The molecular formula of the organic luminescent material (Ir complex) reported in the above-mentioned article is shown below.

[0147]

Embedded image

As described above, if the phosphorescence emission from the triplet exciton can be used, the external emission quantum efficiency three to four times higher than the case of using the fluorescence emission from the singlet exciton can be realized in principle. .

The configuration of this embodiment can be implemented by freely combining with any of the configurations of the first to seventh embodiments.

Embodiment 9 An example of a method for manufacturing a light emitting device of the present invention will be described with reference to FIGS. Here, the switching TFT and the driving T
A method for simultaneously manufacturing the FT and the TFT of the driving portion provided around the pixel portion will be described in detail according to the steps.

First, in this embodiment, Corning # 70
A substrate 900 made of glass such as barium borosilicate glass typified by 59 glass or # 1737 glass or aluminoborosilicate glass is used. Note that the substrate 900 is not limited as long as it is a light-transmitting substrate, and a quartz substrate may be used. Further, a plastic substrate having heat resistance enough to withstand the processing temperature of this embodiment may be used.

Next, as shown in FIG. 13A, a base film 901 made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed over the substrate 900. Although a two-layer structure is used as the base film 901 in this embodiment, a single-layer film of the insulating film or a structure in which two or more layers are stacked may be used. As the first layer of the base film 901, plasma CV
Using method D, a silicon oxynitride film 901a formed using SiH ₄ , NH ₃ , and N ₂ O as a reaction gas is
nm (preferably 50 to 100 nm). In this embodiment, a 50 nm-thick silicon oxynitride film 901a (composition ratio: Si = 32%, O = 27%, N = 24%, H = 17)
%). Next, as a second layer of the base film 901, a silicon oxynitride film 901 b formed using SiH ₄ and N ₂ O as a reaction gas is formed by a plasma CVD method.
The layer is formed to a thickness of 200 to 200 nm (preferably 100 to 150 nm). In this embodiment, a 100-nm-thick silicon oxynitride film 901b (composition ratio: Si = 32%, O = 59)
%, N = 7%, H = 2%).

Next, a semiconductor layer 902 is formed on the underlayer 901.
To 905 are formed. The semiconductor layers 902 to 905 are formed by forming a semiconductor film having an amorphous structure by a known means (sputtering method, L
After forming a film by a PCVD method or a plasma CVD method, a known crystallization treatment (a laser crystallization method, a thermal crystallization method, or a thermal crystallization method using a catalyst such as nickel).
Is performed and the crystalline semiconductor film obtained is patterned into a desired shape. The thickness of the semiconductor layers 902 to 905 is 25 to 80 nm (preferably 30 to 60 nm). Although there is no limitation on the material of the crystalline semiconductor film,
Preferably silicon (silicon) or silicon germanium _{(Si X Ge 1-X (} X = 0.0001~0.02)) may be formed such as an alloy. In this embodiment, the plasma CV
After a 55-nm amorphous silicon film was formed by method D, a solution containing nickel was held on the amorphous silicon film. After dehydrogenation (500 ° C., 1 hour) of this amorphous silicon film, thermal crystallization (550 ° C., 4 hours) is performed, and further, a laser annealing process for improving crystallization is performed. Thus, a crystalline silicon film was formed. Then, the crystalline silicon film is patterned by a photolithography method,
Semiconductor layers 902 to 905 were formed.

After the formation of the semiconductor layers 902 to 905, the semiconductor layers 90 to 905 are controlled to control the threshold value of the TFT.
2 to 905 may be doped with a trace amount of an impurity element (boron or phosphorus).

When a crystalline semiconductor film is formed by a laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, a YAG laser, or a YVO ₄ laser can be used. In the case of using these lasers, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated on a semiconductor film. The crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is set to 300 Hz, and the laser energy density is set to 100 to 4.
00 mJ / cm ² (typically 200 to 300 mJ / cm
² ). When a YAG laser is used, its second harmonic is used and a pulse oscillation frequency of 30 to 300 kHz is used.
And a laser energy density of 300 to 600 mJ /
cm ² (typically 350 to 500 mJ / cm ² ). And a width of 100 to 1000 μm, for example 400 μ
The laser light condensed linearly at m may be irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser light at this time may be set to 50 to 90%.

Next, a gate insulating film 906 covering the semiconductor layers 902 to 905 is formed. The gate insulating film 906 is formed by a plasma CVD method or a sputtering method and has a thickness of 40 to
The insulating film containing silicon is formed to have a thickness of 150 nm. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N =
7%, H = 2%). Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

When a silicon oxide film is used, a TEOS (Tetraethyl Orthosilicate) is formed by a plasma CVD method.
e) and O ₂ were mixed, the reaction pressure was 40 Pa, and the substrate temperature was 30.
It can be formed by discharging at a high-frequency (13.56 MHz) power density of 0.5 to 0.8 W / cm ² at 0 to 400 ° C. The silicon oxide film thus manufactured can obtain favorable characteristics as a gate insulating film by subsequent thermal annealing at 400 to 500 ° C.

Then, a heat-resistant conductive layer 907 for forming a gate electrode on the gate insulating film 906 is
It is formed with a thickness of 0 nm (preferably 250 to 350 nm). The heat-resistant conductive layer 907 may be formed as a single layer,
If necessary, a laminated structure including a plurality of layers such as two layers or three layers may be employed. Ta, T for the heat-resistant conductive layer
It includes an element selected from i and W, an alloy containing the above element, or an alloy film combining the above elements. These heat-resistant conductive layers are formed by a sputtering method or a CVD method, and it is preferable to reduce the impurity concentration to reduce the resistance, and it is particularly preferable that the oxygen concentration be 30 ppm or less. In this embodiment, the W film is 3
It is formed with a thickness of 00 nm. The W film may be formed by a sputtering method using W as a target, or may be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, it is necessary to lower the resistance in order to use it as a gate electrode, and the resistivity of the W film is 20 μΩc.
m or less. The resistivity of the W film can be reduced by enlarging the crystal grains. However, when there are many impurity elements such as oxygen in W, the crystallization is inhibited and the resistance is increased. Thus, in the case of using the sputtering method, a W target having a purity of 99.9999% is used, and further, the W film is formed with sufficient care so as not to mix impurities from the gas phase during film formation. 9 to 20 μΩcm can be realized.

On the other hand, when a Ta film is used for the heat-resistant conductive layer 907, it can be similarly formed by a sputtering method. The Ta film uses Ar as a sputtering gas. Also, if an appropriate amount of Xe or Kr is added to the gas during sputtering,
The internal stress of the film to be formed can be relaxed to prevent the film from peeling. The resistivity of the α-phase Ta film is about 20 μΩcm and can be used for the gate electrode.
The resistivity of the a-film was about 180 μΩcm, and was not suitable for use as a gate electrode. Since the TaN film has a crystal structure close to the α phase, if the TaN film is formed under the Ta film,
A phase Ta film is easily obtained. Although not shown, it is effective to form a silicon film doped with phosphorus (P) with a thickness of about 2 to 20 nm under the heat-resistant conductive layer 907. Thereby, the adhesion of the conductive film formed thereon is improved and oxidation is prevented, and at the same time, the heat-resistant conductive layer 90 is formed.
It is possible to prevent a small amount of an alkali metal element contained in 7 from diffusing into the gate insulating film 906 in the first shape. In any case, the heat-resistant conductive layer 907 has a resistivity of 10 to 5
It is preferable to set it in the range of 0 μΩcm.

Next, a resist mask 908 is formed by using the photolithography technique. And
A first etching process is performed. In this embodiment, an ICP etching apparatus is used, Cl ₂ and CF ₄ are used as etching gases, and RF (13.5) of 3.2 W / cm ² at a pressure of 1 Pa.
(6 MHz) power is supplied to form plasma. 224 mW / cm ² RF on substrate side (sample stage)
(13.56 MHz) power is applied, thereby applying a substantially negative self-bias voltage. Under these conditions, the etching rate of the W film is about 100 nm / min. First
In the etching process, the time for just etching the W film was estimated based on the etching rate, and the time obtained by increasing the etching time by 20% was set as the etching time.

[0161] Conductive layers 909 to 912 having a first tapered shape are formed by the first etching process. The angle of the tapered portion of the conductive layers 909 to 912 is 15 to 30 °
It is formed so that In order to perform etching without leaving a residue, over-etching is performed to increase the etching time at a rate of about 10 to 20%. Silicon oxynitride film (gate insulating film 9) for W film
06) is 2-4 (typically 3),
By the overetching treatment, the exposed surface of the silicon oxynitride film is etched by about 20 to 50 nm.
(FIG. 13 (B))

Then, a first doping process is performed to add an impurity element of one conductivity type to the semiconductor layer. Here, n
A step of adding an impurity element for giving a mold is performed. The mask 908 on which the conductive layer of the first shape is formed is left as it is,
Using the conductive layers 909 to 912 having the tapered shape as masks, an impurity element imparting n-type is added in a self-aligning manner by an ion doping method. An impurity element imparting n-type is added to the tapered portion at the end of the gate electrode and the gate insulating film 906.
Through the process, the dose is set to 1 × 10 ^{13 to} 5 × 10 ¹⁴ at for doping so as to reach the semiconductor layer located thereunder.
oms / cm ² and an acceleration voltage of 80 to 160 keV. As the impurity element imparting n-type, an element belonging to Group 15 of the periodic table, typically phosphorus (P) or arsenic (As) is used. Here, phosphorus (P) is used. By such an ion doping method, an impurity element imparting n-type is added to the first impurity regions 914 to 917 in a concentration range of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms / cm ³ . (FIG. 13
(C))

In this step, depending on the doping conditions, the impurities flow under the first shape conductive layers 909 to 912, and the first impurity regions 914 to 917 are removed from the first shape.
May overlap with the conductive layers 909 to 912 having the shape shown in FIG.

Next, a second etching process is performed as shown in FIG. The etching process is also performed by an ICP etching apparatus, and CF ₄ and C are used as an etching gas.
a mixed gas of l _2, RF power 3.2W / cm ² (13.
56 MHz), bias power 45 mW / cm ² (13.56
MHz) at a pressure of 1.0 Pa. Conductive layers 918 to 92 having the second shape formed under these conditions
1 is formed. A tapered part is formed at the end,
It has a tapered shape in which the thickness gradually increases inward from the end. As compared with the first etching process, the ratio of isotropic etching is increased by the amount of the lower bias power applied to the substrate side, and the angle of the tapered portion is 30 to 60 °. The mask 908 is etched and its edge is shaved, and becomes a mask 922. In the step of FIG. 13D, the surface of the gate insulating film 906 is etched by about 40 nm.

Then, an impurity element imparting n-type is doped under a condition of a high acceleration voltage with a lower dose than in the first doping process. For example, when the accelerating voltage is 70 to 120
keV, a dose of 1 × 10 ¹³ / cm ² , and the first impurity regions 924 to 92 having an increased impurity concentration.
7 and second impurity regions 928 to 931 in contact with the first impurity regions 924 to 927 are formed. In this step, depending on the doping conditions, the impurity
The second impurity regions 928 to 931 extend below the conductive layers 918 to 921 of the second shape.
921 may also occur. The impurity concentration in the second impurity region is 1 × 10 ¹⁶ to 1 × 10 ^{18 at.}
ms / cm ³ . (FIG. 14A)

Then, as shown in FIG. 14 (B),
Semiconductor layers 902 and 905 forming a p-channel TFT
The impurity region 933 having a conductivity type opposite to the one conductivity type (933)
a, 933b) and 934 (934a, 934b). Also in this case, the second shape conductive layers 918 and 921 are used.
Is used as a mask to add an impurity element imparting a p-type, and an impurity region is formed in a self-aligned manner. At this time, a resist mask 932 is formed on the semiconductor layers 903 and 904 forming the n-channel TFT, and the entire surface is covered. The impurity regions 933 and 934 formed here are formed of diborane (B
It is formed by an ion doping method using ₂ H ₆ ). The concentration of the impurity element imparting p-type in the impurity regions 933 and 934 is
The density is set to 2 × 10 ^{20 to} 2 × 10 ²¹ atoms / cm ³ .

However, these impurity regions 933, 9
34 specifically contains an impurity element imparting n-type.
It can be divided into two areas. The third impurity regions 933a and 934a have a size of 1 × 10 ²⁰ to 1 × 10 ²¹ atoms.
includes an impurity element imparting n-type conductivity in a concentration of s / cm ^3,
The fourth impurity regions 933b and 934b are 1 × 10 ¹⁷ to 1
Contains an impurity element imparting n-type at a concentration of × 10 ²⁰ atoms / cm ³ . However, these impurity regions 9
The concentration of the p-type imparting impurity element of 33b and 934b is set to 1 × 10 ¹⁹ atoms / cm ³ or more, and the concentration of the p-type imparting impurity element is set to n in the third impurity regions 933a and 934a. By making the concentration of the impurity element giving the mold 1.5 to 3 times,
Since the third impurity region functions as a source region and a drain region of the p-channel TFT, no problem occurs.

Thereafter, as shown in FIG.
A first interlayer insulating film 937 is formed over the conductive layers 918 to 921 having the above-mentioned shape and the gate insulating film 906. First
The interlayer insulating film 937 may be formed using a silicon oxide film, a silicon oxynitride film, a silicon nitride film, or a stacked film in which these are combined. In any case, the first interlayer insulating film 937 is formed from an inorganic insulating material. The thickness of the first interlayer insulating film 937 is 100 to 200 nm. In the case where a silicon oxide film is used as the first interlayer insulating film 937, TEOS and O ₂ are mixed by plasma CVD, the reaction pressure is 40 Pa, the substrate temperature is 300 to 400 ° C., and the high-frequency (13.56 MHz) power density is used. It can be formed by discharging at 0.5 to 0.8 W / cm ² . In the case where a silicon oxynitride film is used as the first interlayer insulating film 937,
SiH ₄ in plasma CVD, N ₂ O, a silicon oxynitride film formed from NH _3, or SiH _4, N may be formed in a silicon oxynitride film formed from the ₂ O. The manufacturing conditions in this case are a reaction pressure of 20 to 200 Pa, a substrate temperature of 3
00 to 400 ° C. and a high frequency (60 MHz) power density of 0.
It can be formed at 1 to 1.0 W / cm ² . Also, the first
As the interlayer insulating film 937, a silicon oxynitride hydride film formed from SiH ₄ , N ₂ O, and H ₂ may be used.
Similarly, the silicon nitride film is made of SiH ₄ ,
It can be made from NH ₃ .

Then, a step of activating the impurity element imparting n-type or p-type added at each concentration is performed. This step is performed by a thermal annealing method using a furnace annealing furnace. In addition, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. In the thermal annealing method, the oxygen concentration is 1 ppm or less,
Preferably in a nitrogen atmosphere of 0.1 ppm or less 400 ~
The heat treatment is performed at 700 ° C., typically 500 to 600 ° C. In this embodiment, the heat treatment is performed at 550 ° C. for 4 hours.
When a plastic substrate having a low heat-resistant temperature is used as the substrate 501, a laser annealing method is preferably used.

Subsequent to the activation step, the atmosphere gas is changed to 300 to 300% in an atmosphere containing 3 to 100% hydrogen.
A heat treatment is performed at 450 ° C. for 1 to 12 hours to hydrogenate the semiconductor layer. This step is to terminate dangling bonds of 10 ¹⁶ to 10 ¹⁸ / cm ^{3 in} the semiconductor layer by thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed. In any case, the semiconductor layer 9
It is preferable that the defect density in the range of 02 to 905 be 10 ¹⁶ / cm ³ or less.
% May be provided.

Then, a second interlayer insulating film 939 made of an organic insulating material is formed with an average thickness of 1.0 to 2.0 μm. As organic resin materials, polyimide, acrylic,
Polyamide, polyimide amide, BCB (benzocyclobutene) and the like can be used. For example, in the case of using a polyimide of a type that is thermally polymerized after being applied to a substrate, it is formed by firing at 300 ° C. in a clean oven.
In the case of using acrylic, a two-component type is used, and after mixing the main material and the curing agent, the whole surface is applied using a spinner and then pre-heated at 80 ° C. for 60 seconds on a hot plate. Then, it can be formed by firing in a clean oven at 250 ° C. for 60 minutes.

As described above, by forming the second interlayer insulating film 939 from an organic insulating material, the surface can be satisfactorily planarized. In addition, since organic resin materials generally have a low dielectric constant, parasitic capacitance can be reduced. However, since it is hygroscopic and not suitable as a protective film, it is preferable to use it in combination with a silicon oxide film, a silicon oxynitride film, a silicon nitride film, or the like formed as the first interlayer insulating film 937 as in this embodiment. .

Thereafter, a resist mask having a predetermined pattern is formed.
Formed in each semiconductor layer and the source region.
Or a contact reaching the impurity region to be the drain region
Form a hole. Contact hole is dry etch
It is formed by a metal method. In this case, the etching gas is CF_Four,
O_TwoAnd a second gas made of an organic resin material using a mixed gas of He and He.
Is etched first, and then
Etching gas _Four, O_TwoAs the first interlayer insulating film
937 is etched. Furthermore, the selectivity with the semiconductor layer
CHF to increase the etching gas_ThreeSwitch to
The third shape gate insulating film 570 by etching.
Thus, a contact hole can be formed.

Then, a conductive metal film is formed by a sputtering method or a vacuum evaporation method, patterned by a mask, and then etched to form source wirings 940 to 943 and drain wirings 944 to 946. Although not shown, in this embodiment, this wiring is formed of a laminated film of a 50 nm-thick Ti film and a 500 nm-thick alloy film (an alloy film of Al and Ti).

Next, a transparent conductive film is formed on top of the transparent conductive film.
A pixel electrode 947 is formed by forming a pattern with a thickness of 0 nm and patterning (FIG. 15A). In this embodiment, indium tin oxide (IT) is used as a transparent electrode.
O) 2-20% zinc oxide (Z
A transparent conductive film mixed with nO) is used.

The pixel electrode 947 is connected to the drain wiring 9
The driving TFT is formed by overlapping with
And the drain region is electrically connected.

Next, as shown in FIG. 15B, a third interlayer insulating film 949 having an opening at a position corresponding to the pixel electrode 947 is formed. The third interlayer insulating film 949 has insulating properties, functions as a bank, and has a role of separating an organic light emitting layer of an adjacent pixel. In this embodiment, a third interlayer insulating film 949 is formed using a resist.

In this embodiment, the thickness of the third interlayer insulating film 949 is set to about 1 μm, and the opening is formed so as to become wider as it approaches the pixel electrode 947, that is, to form a so-called reverse taper. This is formed by forming a resist, covering a portion other than a portion where an opening is to be formed with a mask, irradiating with UV light, and removing the exposed portion with a developing solution.

As in the present embodiment, the third interlayer insulating film 94
When the organic light-emitting layer 9 is formed in a reverse tapered shape, the organic light-emitting layer is separated between adjacent pixels when an organic light-emitting layer is formed in a later step.
Even if the thermal expansion coefficients of 49 are different, it is possible to suppress the organic light emitting layer from cracking or peeling.

In this embodiment, a resist film is used as the third interlayer insulating film. However, depending on the case, polyimide, polyamide, acryl, BCB may be used.
(Benzocyclobutene), a silicon oxide film, or the like can also be used. The third interlayer insulating film 949 may be an organic substance or an inorganic substance as long as the substance has an insulating property.

Next, an organic light emitting layer 950 is formed by an evaporation method, and a cathode (MgAg electrode) 951 and a protection electrode 952 are formed by an evaporation method. At this time, the organic light emitting layer 9
Prior to forming the pixel electrode 50 and the cathode 951, the pixel electrode 94 is formed.
It is desirable to perform a heat treatment on 7 to completely remove moisture. In this embodiment, the MgAg electrode is used as the cathode of the OLED, but another known material may be used.

As the organic light emitting layer 950, a known material can be used. In this embodiment, a hole transporting layer (Hole transporting layer) and a light emitting layer (Emitting layer) are used.
yer) is used as the organic light emitting layer, but it may be provided with any one of a hole injection layer, an electron injection layer and an electron transport layer. Various examples of such combinations have already been reported, and any of these configurations may be used.

In this embodiment, polyphenylene vinylene is formed as a hole transport layer by a vapor deposition method. The light emitting layer is formed by vapor deposition of a 30% to 40% molecular dispersion of PBD of a 1,3,4-oxadiazole derivative in polyvinyl carbazole, and about 1% of coumarin 6 is used as a green light emitting center. Has been added.

The protective electrode 952 also serves as the organic light emitting layer 95.
Although it is possible to protect 0 from moisture and oxygen, it is more preferable to provide a protective film 953. In this embodiment, a 300-nm-thick silicon nitride film is provided as the protective film 953. This protective film may be formed continuously without opening to the atmosphere after the protective electrode 952.

The protective electrode 952 is provided to prevent the deterioration of the cathode 951, and is typically a metal film containing aluminum as a main component. Of course, other materials may be used. Also,
Since the organic light emitting layer 950 and the cathode 951 are very sensitive to moisture, it is preferable to continuously form the protection electrode 952 without opening to the atmosphere to protect the organic light emitting layer from the outside air.

Note that the thickness of the organic light emitting layer 950 is 10 to 4
00 [nm] (typically 60 to 150 [nm]), cathode 951
Has a thickness of 80 to 200 nm (typically 100 to 150 nm).
[nm]).

Thus, a light emitting device having a structure as shown in FIG. 15B is completed. Note that an overlapping portion 954 of the pixel electrode 947, the organic light emitting layer 950, and the cathode 951 is OL
It corresponds to ED.

A p-channel TFT 960 and an n-channel TFT 961 are TFTs included in a driving circuit,
OS is formed. The switching TFT 962 and the driving TFT 963 are TFTs included in the pixel portion, and the driving circuit TFT and the pixel portion TFT can be formed over the same substrate.

In the case of a light emitting device using an OLED,
The voltage of the power supply of the drive circuit is about 5-6V, and the maximum is 10V
Since the degree is sufficient, deterioration due to hot electrons in the TFT does not cause much problem. Since the driving circuit needs to operate at high speed, it is preferable that the gate capacitance of the TFT is small. Therefore, as in this embodiment, O
In a driver circuit of a light-emitting device using an LED, a second impurity region 929 and a fourth impurity region 933b included in a semiconductor layer of a TFT are formed with gate electrodes 918 and 919, respectively.
It is preferable to adopt a configuration that does not overlap with.

The method for manufacturing the light emitting device of the present invention is not limited to the method described in this embodiment. The light emitting device of the present invention can be manufactured using a known method.

This embodiment can be implemented by freely combining with Embodiments 1 to 8.

[Embodiment 10] In this embodiment, a method for manufacturing a light emitting device different from that of Embodiment 9 will be described.

The steps up to the formation of the second interlayer insulating film 939 are the same as in the fifth embodiment. As shown in FIG. 16A, after forming a second interlayer insulating film 939, the passivation film 9 is in contact with the second interlayer insulating film 939.
81 is formed.

The passivation film 981 is effective for preventing moisture contained in the second interlayer insulating film 939 from entering the organic light emitting layer 950 via the pixel electrode 947 and the third interlayer insulating film 982. It is. Second interlayer insulating film 939
Has an organic resin material, it is particularly effective to provide the passivation film 981 because the organic resin material contains a large amount of moisture.

In this embodiment, the passivation film 981
A silicon nitride film was used.

Thereafter, a resist mask having a predetermined pattern is formed.
Formed in each semiconductor layer and the source region.
Or a contact reaching the impurity region to be the drain region
Form a hole. Contact hole is dry etch
It is formed by a metal method. In this case, the etching gas is CF_Four,
O_TwoAnd a second gas made of an organic resin material using a mixed gas of He and He.
Is etched first, and then
Etching gas _Four, O_TwoAs the first interlayer insulating film
937 is etched. Furthermore, the selectivity with the semiconductor layer
CHF to increase the etching gas_ThreeSwitch to
The third shape gate insulating film 570 by etching.
Thus, a contact hole can be formed.

Then, a conductive metal film is formed by a sputtering method or a vacuum evaporation method, patterned by a mask, and then etched to form source wirings 940 to 943 and drain wirings 944 to 946. Although not shown, in this embodiment, this wiring is formed of a laminated film of a 50 nm-thick Ti film and a 500 nm-thick alloy film (an alloy film of Al and Ti).

Next, a transparent conductive film is formed on the
A pixel electrode 947 is formed by forming a pattern with a thickness of 0 nm and patterning (FIG. 16A). In this embodiment, indium tin oxide (IT) is used as a transparent electrode.
O) 2-20% zinc oxide (Z
A transparent conductive film mixed with nO) is used.

The pixel electrode 947 is connected to the drain wiring 9
The driving TFT is formed by overlapping with
And the drain region is electrically connected.

Next, as shown in FIG. 16B, a third interlayer insulating film 982 having an opening at a position corresponding to the pixel electrode 947 is formed. In this embodiment, when the opening is formed, the side wall is tapered by using a wet etching method. Unlike the case shown in the fifth embodiment, the third
Since the organic light emitting layer formed on the interlayer insulating film 982 is not divided, if the side wall of the opening is not sufficiently gentle, the deterioration of the organic light emitting layer due to the step becomes a serious problem, so care must be taken. It is.

In this embodiment, a film made of silicon oxide is used as the third interlayer insulating film 982. However, depending on the case, polyimide, polyamide, acryl, B
An organic resin film such as CB (benzocyclobutene) can also be used.

Then, before forming the organic light emitting layer 950 on the third interlayer insulating film 982, the third interlayer insulating film 982 is formed.
Is preferably subjected to a plasma treatment using argon to make the surface of the third interlayer insulating film 982 dense. With the above structure, entry of moisture from the third interlayer insulating film 982 into the organic light-emitting layer 950 can be prevented.

Next, an organic light emitting layer 950 is formed by an evaporation method, and a cathode (MgAg electrode) 951 and a protection electrode 952 are formed by an evaporation method. At this time, the organic light emitting layer 9
Prior to forming the pixel electrode 50 and the cathode 951, the pixel electrode 94 is formed.
It is desirable to perform a heat treatment on 7 to completely remove moisture. In this embodiment, the MgAg electrode is used as the cathode of the OLED, but another known material may be used.

As the organic light emitting layer 950, a known material can be used. In this embodiment, a hole transporting layer (Hole transporting layer) and a light emitting layer (Emitting layer) are used.
yer) is used as the organic light emitting layer, but it may be provided with any one of a hole injection layer, an electron injection layer and an electron transport layer. Various examples of such combinations have already been reported, and any of these configurations may be used.

In this embodiment, polyphenylene vinylene is formed as a hole transport layer by a vapor deposition method. The light emitting layer is formed by vapor deposition of a 30% to 40% molecular dispersion of PBD of a 1,3,4-oxadiazole derivative in polyvinyl carbazole, and about 1% of coumarin 6 is used as a green light emitting center. Has been added.

The organic light emitting layer 95 is also used as the protective electrode 952.
Although it is possible to protect 0 from moisture and oxygen, it is more preferable to provide a protective film 953. In this embodiment, a 300-nm-thick silicon nitride film is provided as the protective film 953. This protective film may be formed continuously without opening to the atmosphere after the protective electrode 952.

The protective electrode 952 is provided to prevent the deterioration of the cathode 951, and is typically a metal film containing aluminum as a main component. Of course, other materials may be used. Also,
Since the organic light emitting layer 950 and the cathode 951 are very sensitive to moisture, it is preferable to continuously form the protection electrode 952 without opening to the atmosphere to protect the organic light emitting layer from the outside air.

The thickness of the organic light emitting layer 950 is 10 to 4
00 [nm] (typically 60 to 150 [nm]), cathode 951
Has a thickness of 80 to 200 nm (typically 100 to 150 nm).
[nm]).

Thus, a light emitting device having a structure as shown in FIG. 16B is completed. Note that an overlapping portion 954 of the pixel electrode 947, the organic light emitting layer 950, and the cathode 951 is OL
It corresponds to ED.

A p-channel TFT 960 and an n-channel TFT 961 are TFTs included in a drive circuit,
OS is formed. The switching TFT 962 and the driving TFT 963 are TFTs included in the pixel portion, and the driving circuit TFT and the pixel portion TFT can be formed over the same substrate.

[0211] The method for manufacturing the light emitting device of the present invention is not limited to the manufacturing method described in this embodiment. The light emitting device of the present invention can be manufactured using a known method.

This embodiment can be implemented by freely combining with Embodiments 1 to 9.

(Embodiment 11) Since the light-emitting device is of a self-luminous type, it has better visibility in a bright place and a wider viewing angle than a liquid crystal display. Therefore, it can be used for display portions of various electronic devices.

Electronic devices using the light emitting device of the present invention include a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproducing device (car audio, audio component, etc.), a notebook personal computer, Game devices, portable information terminals (mobile computers, mobile phones, portable game machines, electronic books, etc.), and image reproducing devices provided with recording media (specifically, DVD: Digital Versat
device that reproduces a recording medium such as an ile Disc and displays the image of the recording medium). In particular,
It is desirable to use a light-emitting device for a portable information terminal that frequently views a screen from an oblique direction, since a wide viewing angle is regarded as important. FIG. 17 shows specific examples of these electronic devices.

FIG. 17A shows an organic light-emitting display device.
A housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like are included.
The light emitting device of the present invention can be used for the display portion 2003. Since the light-emitting device is a self-luminous type, it does not require a backlight and can be a display portion thinner than a liquid crystal display. The organic light-emitting display device is for personal computers, TVs,
All display devices for displaying information, such as for broadcast reception and advertisement display, are included.

FIG. 17B shows a digital still camera, which includes a main body 2101, a display portion 2102, an image receiving portion 2103,
An operation key 2104, an external connection port 2105, a shutter 2106, and the like are included. The light emitting device of the present invention has a display unit 210.
2 can be used.

FIG. 17C shows a notebook personal computer, which includes a main body 2201, a housing 2202, and a display portion 2.
203, keyboard 2204, external connection port 220
5, including a pointing mouse 2206 and the like. The light emitting device of the present invention can be used for the display portion 2203.

FIG. 17D shows a mobile computer, which includes a main body 2301, a display portion 2302, and a switch 230.
3, an operation key 2304, an infrared port 2305, and the like. The light emitting device of the present invention can be used for the display portion 2302.

FIG. 17E shows a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, and includes a main body 2401, a housing 2402, a display portion A 2403, a display portion B 2404, and a recording medium ( DVD, etc.) reading unit 240
5, operation keys 2406, a speaker unit 2407, and the like. The display portion A 2403 mainly displays image information, and the display portion B 2404 mainly displays character information. In the light emitting device of the present invention, the display portions A, B 2403 and 2404 are used.
Can be used. Note that the image reproducing device provided with the recording medium includes a home game machine and the like.

FIG. 17F shows a goggle-type display (head-mounted display).
1, including a display unit 2502 and an arm unit 2503. The light emitting device of the present invention can be used for the display portion 2502.

FIG. 17G shows a video camera, which includes a main body 2601, a display portion 2602, a housing 2603, an external connection port 2604, a remote control receiving portion 2605, and an image receiving portion 260.
6, a battery 2607, a voice input unit 2608, operation keys 2609, and the like. The light emitting device of the present invention has a display section 260.
2 can be used.

Here, FIG. 17H shows a mobile phone, which includes a main body 2701, a housing 2702, a display portion 2703, a voice input portion 2704, a voice output portion 2705, operation keys 2706,
An external connection port 2707, an antenna 2708, and the like are included.
The light emitting device of the present invention can be used for the display portion 2703. Note that the display portion 2703 displays white characters on a black background, so that power consumption of the mobile phone can be suppressed.

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

[0224] The electronic device may be 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 organic light emitting material is very high, the light emitting device is preferable for displaying moving images.

[0225] In the light emitting 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 a light emitting device is used for a portable information terminal, particularly a display portion mainly for character information such as a mobile phone or a sound reproducing device, the light emitting portion is driven to form character information with a non-light emitting portion as a background. It is desirable to do.

As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electronic devices in various fields. Further, the electronic apparatus of this embodiment may use the light emitting device having any of the configurations shown in Embodiments 1 to 10.

[0227]

According to the present invention, with a structure which is easy to use, even if the organic light emitting layer is deteriorated, a decrease in luminance of the OLED is suppressed, and as a result, a clear image can be displayed. Further, in the case of a light emitting device for color display using OLED corresponding to each color, even if the organic light emitting layer of the OLED deteriorates at a different speed for each corresponding color, it is possible to prevent the luminance balance of each color from being lost. , It is possible to continue displaying a desired color.

In addition, the temperature of the organic light emitting layer is determined by the outside air temperature and OL temperature.
The ED panel is affected by heat or the like generated by the ED panel itself. Even in such a case, it is possible to suppress a change in the luminance of the OLED, and to prevent an increase in power consumption with an increase in temperature. In the case of a color display light-emitting device, a change in luminance of each color OLED can be suppressed without being affected by a change in temperature, so that the balance of luminance of each color can be prevented from being lost and a desired color can be displayed. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram of a light emitting device of the present invention.

FIG. 2 illustrates a change in luminance due to deterioration during constant current driving or constant voltage driving.

FIG. 3 shows a change in current with temperature of an organic light emitting layer.

FIG. 4 is a pixel circuit diagram of the light emitting device of the present invention.

FIG. 5 shows a change in voltage due to correction.

FIG. 6 is a block diagram of a correction circuit.

FIG. 7 is a diagram illustrating a relationship between a deviation current and a correction voltage.

FIG. 8 is a pixel circuit diagram of a light emitting device of the present invention.

FIG. 9 illustrates a method for driving a light-emitting device of the present invention.

FIG. 10 is a block diagram of a driving circuit.

FIG. 11 is an external view of a light emitting device of the present invention.

FIG. 12 is an external view of a light emitting device of the present invention.

FIG. 13 illustrates a method for manufacturing a light-emitting device of the present invention.

FIG. 14 illustrates a method for manufacturing a light-emitting device of the present invention.

FIG. 15 illustrates a method for manufacturing a light-emitting device of the present invention.

FIG. 16 illustrates a method for manufacturing a light-emitting device of the present invention.

FIG. 17 is a diagram of an electronic device using the light-emitting device of the present invention.

FIG. 18 shows changes due to deterioration of voltage-current characteristics and current-luminance characteristics of an OLED.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09G 3/20 G09G 3/20 642P 670 670J 670L H05B 33/08 H05B 33/08 33/14 33/14 A

Claims (17)

[Claims] 1. A light emitting device having an OLED, a first means for measuring a current flowing between a first electrode and a second electrode of the OLED, and the measured current value being a reference. A second means for comparing a current value; and a difference between the measured current value and the reference current value, a current flowing between the first electrode and the second electrode of the OLED serving as the reference. So that it approaches the current value
3. A light emitting device comprising: a third means for correcting a voltage between a first electrode and a second electrode of the OLED. 2. A light emitting device provided with a plurality of pixels having OLEDs, wherein a total of currents flowing between a first electrode and a second electrode of all OLEDs provided in the plurality of pixels is measured. First
And a second means for comparing the measured current value with a reference current value, and a second means for comparing the measured current value and the reference current value with each other provided in the plurality of pixels. First OLED
Between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels, such that the total current flowing between the first and second electrodes approaches the reference current value. And a third means for correcting the voltage. 3. A light emitting device provided with a plurality of pixels having OLEDs, wherein a total of currents flowing between a first electrode and a second electrode of all OLEDs provided in the plurality of pixels is measured. First
And a second means for comparing the measured current value with a reference current value, and a second means for comparing the measured current value and the reference current value with each other provided in the plurality of pixels. First OLED
Between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels, such that the total current flowing between the first and second electrodes approaches the reference current value. A third means for correcting a voltage, wherein each time the difference between the measured current value and the reference current value changes by a certain width, the corrected voltage changes by a certain magnitude. Characteristic light emitting device. 4. A light emitting device provided with a plurality of pixels having OLEDs in a pixel portion, wherein a current flowing between a first electrode and a second electrode of all OLEDs provided in the plurality of pixels is provided. First to measure the sum
And a second means for comparing the measured current value with a reference current value, and a second means for comparing the measured current value and the reference current value with each other provided in the plurality of pixels. First OLED
Between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels, such that the total current flowing between the first and second electrodes approaches the reference current value. A third means for correcting a voltage, wherein the third means is provided in the pixel unit when measuring the total current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels. A light emitting device characterized by displaying the image of (1). 5. A light emitting device in which a plurality of pixels having OLEDs are provided in a pixel portion, wherein a current flowing between a first electrode and a second electrode of all OLEDs provided in the plurality of pixels is provided. First to measure the sum
And a second means for comparing the measured current value with a reference current value, and a second means for comparing the measured current value and the reference current value with each other provided in the plurality of pixels. First OLED
Between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels, such that the total current flowing between the first and second electrodes approaches the reference current value. A third means for correcting a voltage, wherein the display is performed on the pixel unit when a total current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels is measured. A light emitting device characterized in that the reference current value differs depending on an image to be obtained. 6. A light emitting device in which a plurality of pixels each having an OLED are provided in a pixel portion, wherein the pixel portion includes an OLED and at least one TFT.
A plurality of pixels having: a first means for controlling light emission of the OLED by the TFT, and measuring a total current flowing between a first electrode and a second electrode of all the OLEDs; A second means for comparing the measured current value with a reference current value; and a first electrode and a second electrode of all the OLEDs based on a difference between the measured current value and the reference current value. And a third means for correcting the voltage between the first electrode and the second electrode of all the OLEDs so that the total current flowing between the OLEDs approaches the reference current value. Light emitting device. 7. The OLE device according to claim 1, wherein the first, second, or third means includes the OLE.
A light-emitting device provided for each color corresponding to D. 8. A light-emitting device having an OLED and a variable power supply, comprising: an ammeter for measuring a current flowing between a first electrode and a second electrode of the OLED; The OL value is compared such that the current flowing between the first electrode and the second electrode of the OLED approaches the reference current value.
A light emitting device comprising: a correction circuit that corrects a voltage between a first electrode and a second electrode of the ED by controlling the variable power supply. 9. A light-emitting device provided with a plurality of pixels having OLEDs, wherein a total of currents flowing between first and second electrodes of all OLEDs provided in the plurality of pixels is measured. And the measured current value is compared with a reference current value, and the sum of the current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels is A correction circuit that corrects the voltage between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels by controlling a variable power supply so as to approach a reference current value. A light-emitting device comprising: 10. A light-emitting device provided with a plurality of pixels having OLEDs, wherein a total of currents flowing between first and second electrodes of all OLEDs provided in the plurality of pixels is measured. And the measured current value is compared with a reference current value, and the sum of the current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels is A correction circuit that corrects the voltage between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels by controlling a variable power supply so as to approach a reference current value. A light-emitting device, wherein the correction voltage changes by a constant magnitude each time the difference between the measured current value and the reference current value changes by a certain width. 11. A light-emitting device in which a plurality of pixels having OLEDs are provided in a pixel portion, wherein a current flowing between a first electrode and a second electrode of all OLEDs provided in the plurality of pixels is provided. An ammeter for measuring the sum, comparing the measured current value with a reference current value, and measuring the current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels. Correction for correcting the voltage between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels by controlling a variable power supply so that the sum approaches the reference current value. A specific image is displayed on the pixel portion when measuring the total current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels. A light emitting device characterized by the above-mentioned. 12. A light-emitting device in which a plurality of pixels having OLEDs are provided in a pixel portion, wherein a current flowing between the first electrode and the second electrode of all OLEDs provided in the plurality of pixels is provided. An ammeter for measuring the sum, comparing the measured current value with a reference current value, and measuring the current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels. Correction for correcting the voltage between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels by controlling a variable power supply so that the sum approaches the reference current value. A circuit for measuring the total current flowing between the first electrode and the second electrode of all the OLEDs provided in the plurality of pixels. Characterized by different current values Light equipment. 13. The light emitting device according to claim 8, wherein said variable power supply, said ammeter and said correction circuit are provided for each color of said OLED. apparatus. 14. The second substrate on which the correction circuit or the ammeter is formed is mounted on the first substrate on which the OLED is formed, according to any one of claims 8 to 13. A light-emitting device characterized in that: 15. The COG according to claim 8, wherein the second substrate on which the correction circuit or the ammeter is formed is formed on a first substrate on which the OLED is formed. A light emitting device characterized by being attached by a method. 16. The method according to claim 8, wherein the second substrate on which the correction circuit or the ammeter is formed is a wire on the first substrate on which the OLED is formed. A light-emitting device which is attached by a bonding method. 17. The light emitting device according to claim 1, wherein a gray scale is displayed by controlling a light emitting time of said OLED by a digital video signal.