JP3389653B2 - Organic electroluminescent panel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and an organic electroluminescent panel, and more particularly to a thin film type device which emits light by applying an electric field to a light emitting layer made of an organic compound.

[0002]

2. Description of the Related Art Conventionally, as a thin film type electroluminescent (EL) element, Zn which is a II-VI group compound semiconductor of an inorganic material has been used.
It is general that S, CaS, SrS, etc. are doped with Mn or a rare earth element (Eu, Ce, Tb, Sm, etc.), which is a luminescent center, but EL elements made from the above inorganic materials are 1). AC drive required (50 to 1000 Hz), 2)
There is a problem that the driving voltage is high (up to 200 V), 3) full colorization is difficult (especially blue color is a problem), and 4) the cost of the peripheral driving circuit is high.

However, in recent years, in order to improve the above problems,
EL devices using organic thin films have been developed. In particular, the electrode type was optimized to improve the efficiency of carrier injection from the electrode in order to increase the luminous efficiency, and an organic hole transport layer made of an aromatic diamine and a light emitting layer made of an aluminum complex of 8-hydroxyquinoline. Of an organic electroluminescence device provided with a light emitting diode (Appl. Phys. L
ett. , 51, p. 913, 1987), the luminous efficiency is significantly improved as compared with a conventional EL device using a single crystal such as anthracene. The structure of the above element is shown in FIG.

[0004]

In order to use the above organic electroluminescent device as a light source or as a display device, stability of light emission luminance is required. However, in the conventional organic electroluminescent device, the light emission characteristics, especially the light emission luminance, changes with the change in ambient temperature (J. Electr).
ochem. Soc. , 139, 641, 1992
Is a practical problem. As an example of the organic electroluminescence device having the structure shown in FIG. 1, N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-as a hole transport layer is formed on ITO as an anode. A device in which biphenyl-4,4′-diamine (TPD) is 60 nm, an aluminum complex of 8-hydroxyquinoline is 75 nm as a light emitting layer, and a magnesium-silver alloy (composition having an atomic ratio of 10: 1.5) is 150 nm in thickness as a cathode. 24 hours after making
FIG. 2 shows the results of measuring the temperature dependence of the emission brightness of this device in a nitrogen atmosphere after stabilizing the brightness by conducting an aging treatment by applying current at a current density of mA / cm ² . Under the condition of constant current driving (15 mA / cm ² ), the emission brightness tends to decrease and the driving voltage tends to decrease as the ambient temperature rises. Possible causes for this are temperature quenching of the fluorescence of the organic light emitting material and temperature change of the charge injection barrier at the electrode interface.

As described above, the fact that the light emission luminance changes depending on the ambient temperature is a big problem as a light source for a facsimile, a copying machine, a backlight of a liquid crystal display, etc.
This characteristic is not preferable as a display element such as a flat panel display. The present inventors, in view of the above situation,
An object of the present invention is to provide an organic electroluminescence device that can obtain stable light emission luminance even with a change in ambient temperature and an organic electroluminescence panel including the organic electroluminescence device and an active matrix drive circuit on the same substrate. .

[0006]

The summary of the present invention is as follows.
An organic electroluminescent device having an organic light emitting layer sandwiched by an anode and a cathode on a substrate; and the organic electric field on the substrate.
An active matrix circuit that drives the light-emitting elements
A digital organic light emitting panel, wherein the active matrix
Trix circuit is SCAN
C, which is a pole and DATA electrode, and an electrode for supplying current
A SCAN signal (an input signal of the SCAN electrode) is output based on an output value from the temperature detector that has an OM electrode and is provided in the vicinity of the organic electroluminescent device and the temperature detection circuit .
DATA signal (DATA electrode input for pulse width)
By varying the pulse width of the signal), and the organic light emitting panel, characterized in that it comprises means for determining a driving dynamic current of the organic light emitting diode, on a substrate, which is sandwiched between the anode and the cathode an organic An organic electroluminescence panel comprising an organic electroluminescence device having a light emitting layer and an active matrix circuit for driving the organic electroluminescence device on the substrate, wherein the active matrix circuit is responsive to a switching signal. A first thin film transistor which is turned on and off and charges and discharges a storage capacitor according to a light emission signal, and O according to a discharge voltage from the storage capacitor.
A second thin film transistor which is turned on and off to control light emission and non-light emission of the organic electroluminescence element, and a temperature detector provided in proximity to the organic electroluminescence panel, and the temperature detection circuit. Based on the output value from
Of the input signal of the gate electrode of the first thin film transistor
The source voltage of the first thin film transistor with respect to the pulse width
By changing the pulse width of the pole input signal, the second
Of controlling the gate voltage of the thin film transistor, resides in the organic electroluminescent panel, characterized in that it comprises means for determining a driving dynamic current of the organic light emitting diode. Means for determining the upper asked dynamic current is a digital memory or analog computing circuitry.

The organic electroluminescent device and the organic electroluminescent panel of the present invention will be described below with reference to the accompanying drawings. Figure 1
1 is a cross-sectional view schematically showing a structural example of a general organic electroluminescent element used in the present invention, in which 1 is a substrate, 2 is an anode, 3 is a hole transport layer, 4 is a light emitting layer, and 5 is a cathode. Respectively.

The substrate 1 serves as a support for the organic electroluminescent element, and is made of quartz or glass. An anode 2 is provided on the substrate 1, and the anode 2 is usually gold,
With a metal such as silver, palladium, platinum, a metal oxide such as an oxide of indium and / or tin (abbreviated as ITO hereinafter), copper iodide, or a conductive polymer such as poly (3-methylthiophene) Composed.

The compound used in the hole transport layer 3 provided on the anode 2 is, for example, JP-A-59-194.
N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'-biphenyl described in US Pat. No. 4,175,960 and columns 13-14. -4,4'-Diamine: 1,1'-bis (4-di-p-tolylaminophenyl) cyclohexane and other aromatic amine compounds, hydrazone compounds described in JP-A-2-311591, US Patent No. 4,95
The silazane compound etc. which are described in the 0,950 gazette are mentioned. These compounds may be used alone, or may be used as a mixture if necessary. In addition to the above compounds, polyvinylcarbazole and polysilane (Appl. Phys. Lett., Vol. 59, 2760)
P., 1991) and other polymeric materials can also be used.

As a material used for the light emitting layer 4, an aromatic compound such as tetraphenyl butadiene (see JP-A-57-57).
No. 51781), a metal complex such as an aluminum complex of 8-hydroxyquinoline (JP-A-59-19439).
3), a cyclopentadiene derivative (Japanese Patent Laid-Open No. Hei 2)
-289675), perinone derivative (see JP-A-2-289676), oxadiazole derivative (see JP-A-2-216791), bis-styrylbenzene derivative (JP-A 1-245087, 2). -22284), perylene derivatives (see JP-A-2-189890 and 3-791), coumarin compounds (see JP-A-2-191694 and 3-792), rare earth complexes (see JP-A-1
-256584), distyrylpyrazine derivatives (see JP-A-2-252793), p-phenylene compounds (see JP-A-3-33183), thiadiazolopyridine derivatives (see JP-A-3-37292), Examples thereof include a pyrrolopyridine derivative (see JP-A-3-37293) and a naphthyridine derivative (see JP-A-3-203982).

The cathode 5 plays a role of injecting electrons into the light emitting layer 4. The material used for the cathode 5 is preferably a metal having a low work function in order to efficiently inject electrons, and an appropriate metal such as tin, magnesium, indium, aluminum, silver or an alloy thereof is used. In the present invention, in addition to the structure shown in FIG. 1, an organic electroluminescence device having the following layer structure can be used.

[0012]

[Table 1] Anode / organic light emitting layer / cathode anode / organic light emitting layer composed of polymer / cathode anode / organic light emitting layer dispersed in polymer / cathode anode / hole transporting layer / organic electron transporting light emitting layer / cathode Anode / organic hole-transporting light-emitting layer / organic electron-transporting layer / cathode Anode / hole-transporting layer / organic electron-transporting light-emitting layer / electron-transporting layer / cathode Next, the organic electroluminescent panel of the present invention will be described. The organic electroluminescent panel selects one line at a time in the X direction with respect to the pixels composed of the organic electroluminescent elements arranged in an XY matrix, and gives display signals of the respective pixels from electrodes in the Y direction to obtain a display signal for each pixel. The selection signal of is operated one line at a time so that the entire screen is displayed in one cycle. In this panel, each pixel circuit has a memory function. This is because, unlike the case of liquid crystal, if a current is passed only during selection (the scanning electrode of a certain pixel is ON and a display signal is being applied), the pixel will emit light only at the selected moment. , Because the entire screen cannot be displayed continuously. Therefore, it is necessary to provide a memory on the circuit for maintaining the display state from the time of selection to the time of the next selection after making a round of the screen. Then, a circuit that can be driven by current is used. Specifically, the current density flowing through the device is usually 1000 times or more that of a drive circuit for liquid crystal.

The above is the basic circuit function, but the contrast is sufficiently large as a display panel.
Further consideration was given to the large aperture ratio of the screen and the absence of crosstalk. FIG. 3 shows an active matrix drive circuit including a thin film transistor (TFT) and a capacitor for one pixel. This circuit uses two TFs for each pixel.
It is composed of T (TFT1, TFT2) and one capacitor (C), and realizes current driving and memory property. There are two electrodes (SCAN electrode and DATA electrode) for driving signals, which are similar to those for liquid crystal, but there is a COM electrode for supplying current in addition to this, and a point that a voltage is always applied is different. Since the capacitor is formed between the constant potential COM electrode and the constant potential COM electrode, it has a circuit structure resistant to noise.

The operation of the device will be described below. Although the TFT is expressed as an FET in the circuit diagram of FIG.
Has basically the same structure and operation as the MOS-FET, and can switch between the source and drain electrodes by the gate potential. The method of giving a signal for driving is selected for each line, and an ON or OFF signal is given for each pixel in the selected line. The electrodes for selection are SCAN electrodes, and the electrodes that give signals are DATA.
It is an electrode. Now, the selected state, that is, the SCAN signal (SC
When the input signal of the AN electrode) is HIGH, TFT1 is ON
And the DATA signal is HI for the potential of the intermediate electrode FE.
GH is HIGH, LOW is LOW. Therefore, if the DATA signal is HIGH, the TFT 2 is turned ON and the output potential (pixel electrode potential) becomes HIGH. If the DATA signal is LOW, the TFT2 is turned off and the output potential is LOW. After that, when the SCAN signal becomes LOW, that is, in the non-selected state, the TFT1 is turned off.
However, the potential of the intermediate electrode FE is held by the capacitor C and does not change, and the state of the output potential does not change even if the DATA signal changes. The output potential changes because the line including this pixel is in the selected state again, that is, the SCAN signal becomes HIGH, and a signal different from the previous one is DATA.
It is when given to the electrodes. With this circuit, it is possible to drive an active matrix system even if it is a current drive type.

As a material of the TFT used in the active matrix circuit of the present invention, amorphous silicon (a-
Si), polycrystalline silicon (poly-Si), and cadmium selenide (CdSe). As the TFT structure, what is called an inverted stagger type is preferably adopted. As a typical example, an inverted stagger type a-SiTF
T is shown in FIG. The a-Si TFT is formed on the glass substrate 6. As the gate electrode 7, molybdenum, tantalum, aluminum, chromium, a laminated film or alloy thereof, or the like is used. The gate electrode is usually formed by an electron beam evaporation method or a sputtering method. A silicon nitride film (SiN _x ) is used as the gate insulating film 8, and an i-type a-Si layer 9 and an n ⁺ -type a-Si layer 10 are laminated thereon. The silicon nitride film (SiN _x ), the i-type a-Si layer, and the n ⁺ -type a-Si layer are usually continuously formed by the plasma CVD method. After forming the window in the n ⁺ type a-Si layer 10, the source and drain electrodes 11a and 11b are formed. The same metal as the gate electrode is used for the source and drain electrodes. In the above-described a-Si TFT, electric charges are induced on the surface of the i-type a-Si semiconductor layer by the gate potential, and the switching operation between the source and drain electrodes is performed depending on the presence or absence of the electric charges. The n ⁺ type a-Si is a contact layer for facilitating the transfer of charges to the electrodes.

[0016]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist. Example 1 A method for stabilizing the emission brightness of an organic electroluminescent device regardless of ambient temperature will be described with reference to the accompanying drawings.

FIG. 5 is a block diagram showing a drive circuit for an organic electroluminescent device according to the present invention. 20 is the organic electroluminescent device, 21 is a driving power source for the device, and 22 is the temperature of the organic electroluminescent device 20. In order to detect, a temperature detector arranged in the vicinity thereof, 23 is an A / D converter for converting an analog signal (V _temp ) from the temperature detector 22 into a digital signal,
Reference numeral 24 is a ROM memory in which data for converting the output of the A / D converter 23 into a drive voltage value or drive current value of the drive power supply section 21 is stored in advance. 25 is a digital output from the ROM memory, which is a drive power supply section. D sent as control signal of 21
/ A converter. A / D converter 23, ROM memory 2
4. All D / A converters have a data length of 8 bits. FIG. 6 shows a circuit diagram of the temperature detector 22. In the figure, 27 is a thermistor having a negative temperature characteristic, and 28 is a fixed resistor. In the following, for simplification, 22 is simply called a thermistor.

Next, the operation of the first embodiment will be described. First, the operation of the temperature detector 22 will be described. Figure 6
The thermistor is, for example, model P manufactured by Takara Industry Co., Ltd.
ZL-64 (negative temperature coefficient B: 3450, reference resistance value at 25 ° C .: 10 KΩ) can be used. Fixed resistance 2
FIG. 7 shows the temperature characteristics of the output (V _temp ) when 8 is 10 KΩ and the applied voltage is 15V.

Next, a method of setting conversion data in the ROM memory will be described. Since the emission brightness of the organic electroluminescent device linearly decreases with respect to temperature as shown in FIG.
As shown in the following formula (1), the light emission luminance L is expressed as a function of the ambient temperature T (in the formula, a and L0 are constants).

[0020]

## EQU00001 ## L = L0-a.multidot.T (1) The output voltage of the temperature detector is represented by the following equation (2) as a function of ambient temperature, as shown in FIG. V0
Is a constant).

[0021]

V _temp = V _temp0 −b · T (2) Here, when the ambient temperature changes by ΔT with respect to the standard temperature, the brightness change is ΔL, and the output change of the temperature detector is ΔV.
_{Given temp} , the following equations (3) and (4) are obtained from the above equations (1) and (2).

[0022]

ΔL = −a · ΔT (3) ΔV _temp = −b · ΔT (4) The following formula (5) is obtained from the above formulas (3) and (4).

[0023]

ΔL = (a / b) ΔV _temp (5) On the other hand, the current density-luminance luminance characteristic of the organic electroluminescent device is
The emission brightness is in a form proportional to the current density. I, which is the anode
N, N′-diphenyl-as a hole transport layer on the TO
N, N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (TPD) is 60 nm, 8-hydroxyquinoline aluminum complex is 75 nm as a light emitting layer, and magnesium and silver are cathodes. FIG. 8 shows current density-luminance luminance characteristics of a device in which an alloy (composition having an atomic ratio of 10: 1.5) of 150 nm is laminated. The emission brightness of the organic electroluminescence device is determined by the driving current I as shown in the following formula (6).
Is a function of. (In the formula, c is a constant).

[0024]

L = c · I (6) Therefore, in order to compensate the brightness change ΔL due to the temperature change ΔT, the current change ΔI represented by the following formula (7) may be given.

[0025]

[6] ΔI = - (a / bc) ΔV temp ... (7) driving the power supply unit 21, in the case of constant-current drive, the basic circuit of FIG. It is composed of an amplifier (A) and resistors R _{1 to} R _5, and an output current (I _out ) proportional to the input voltage (V _in ) is obtained by the following equation (8).

[0026]

## _EQU00007 ## I _out = (R ₅ / R ₃ R ₄ ) V _in (8) Finally, the voltage change represented by the following equation (9) can be used as the input voltage of the driving power supply unit. For example, the emission brightness is constant regardless of the ambient temperature: ΔV _in = − (a / bc) (R ₃ · R ₄ / R ⁵ ) ΔV _temp (9) As described above, temperature conversion in the ROM memory The data can be easily obtained from the characteristics of FIG. 2, FIG. 7, FIG. 8 and FIG.

The digital output of the ROM memory, which is converted based on the temperature data by using the output of the A / D converter 23 as an input, is amplified by the variable voltage amplifier 26 through the D / A converter 25, and then is driven by the driving power supply unit. Used as the input voltage of. Second Embodiment In the first embodiment described above, the relationship between the input voltage of the driving power supply unit and the temperature is converted by the ROM memory, but the ROM memory may not be used and the analog arithmetic circuit may be used. Figure 1
FIG. 0 is a block diagram of a drive circuit for an organic electroluminescence device in Example 2. In FIG. 10, reference numeral 30 denotes a subtracter, 31
Is an inverting amplifier, 32 is an adder, and the other components are the same as those in FIG.

Next, the operation of the second embodiment will be described. Since the output voltage V _temp of the temperature detector is expressed by the equation (2) of the first embodiment, the subtractor 30 in FIG.
[Delta] V _temp is calculated by subtracting the _temp0, followed by an inverting amplifier 31 the value - (a / bc) (R 3 · R 4 /
R ₅ ), and the reference input voltage V
If 0 is added, the same effect as that of the first embodiment can be obtained.

Example 3 Next, a method for stabilizing the emission brightness of the organic electroluminescent panel regardless of the ambient temperature will be described with reference to the accompanying drawings. FIG. 11 is a block diagram of a drive circuit for an organic electroluminescent panel according to the third embodiment. In FIG. 11, reference numeral 40 is an organic electroluminescence panel, 41 is an active matrix drive circuit, and the other components are the same as those in FIG.

Next, the operation of the third embodiment will be described.
Although the basic operation is the same as that of the first embodiment, the output of the temperature detector is fed back to the input voltage of the constant current power source in the first embodiment, but in the third embodiment, the C circuit shown in FIG.
The voltage applied to the OM electrode is fed back to compensate the temperature dependence of the brightness of the entire organic electroluminescent panel.

Embodiment 4 As a method of controlling the brightness of the organic electroluminescence panel, there is a method of changing the pulse width of the DATA signal with respect to the pulse width of the SCAN signal, unlike the control of the COM voltage in the third embodiment. The operation of controlling the brightness by changing the pulse width will be described. SCAN signal is HIGH
When the TFT1 is turned on and the TFT1 is turned on, the gate voltage FE of the TFT2 is the capacitor C charged by the DATA signal.
Controlled by the voltage of. In the timing chart of FIG. 13, the FE voltage can be changed by shortening the pulse width td of the DATA signal with respect to the pulse width ts of the SCAN signal. The relationship between the pulse width of the DATA signal and the FE potential is the charging characteristic of the capacitor C shown in FIG. 14, and the FE voltage is controlled to V ₁ and V ₂ by changing the pulse width to t ₁ and t _2. You can V ₀ is SC
It represents the maximum voltage that can be charged within the time of the pulse width (ts) of the AN signal.

In the structure shown in FIG. 4, the gate length is 20 μm,
A-Si TFT manufactured with a gate width of 600 μm
The FET characteristics of (TFT2) are shown in FIG. The drain current of the TFT 2 can be controlled by controlling the FE voltage according to the pulse width of the DATA signal, that is, the gate voltage of the TFT 2. In the case of FIG. 15, the drain current changes to I ₁ and I ₂ according to the gate voltages V ₁ and V ₂ . The current density-luminance luminance characteristic of the organic electroluminescent device is
As shown in FIG. 8, since the emission brightness is in proportion to the current density, the current flowing from the pixel electrode to the organic electroluminescent element is controlled by the TFT 2 to control the emission brightness which is the output from the organic electroluminescent element. can do. Considering the relationship between the pulse width of the DATA signal and the light emission brightness, set the conversion data of the ambient temperature to the contents of the ROM memory, and
By feeding back the circuit for controlling the pulse width of the DATA signal of the matrix circuit, it is possible to obtain an organic electroluminescence panel which stably emits light with a constant brightness even when the ambient temperature changes.

[0033]

According to the present invention, based on the output values from the temperature detector and the temperature detection circuit provided in the vicinity of the organic electroluminescent element and the organic electroluminescent panel, the organic electroluminescent element and the organic electroluminescent panel are displayed. By providing the means for determining the driving voltage or the driving current, it is possible to achieve an organic electroluminescent device and an organic electroluminescent panel whose emission brightness is stable even with changes in ambient temperature.

Therefore, the organic electroluminescent device and the organic electroluminescent panel of the present invention are used in the field of flat panel displays (for example, computers and wall televisions for OA, FA, and LA) and display panels for measuring instruments and liquid crystal displays. It can be applied to a backlight light source, a light source for a copying machine, etc., and its technical value is great.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescence device used in the present invention.

FIG. 2 is a measurement example of the ambient temperature dependence of the emission luminance and the driving voltage of the organic electroluminescence device.

FIG. 3 is a circuit diagram for driving the organic electroluminescent panel of the present invention.

FIG. 4 is an example of a TFT structure used in an organic electroluminescence panel driving circuit of the present invention.

FIG. 5 is a block diagram of a drive circuit for an organic light emitting device of the present invention.

FIG. 6 is an example of a circuit diagram of a temperature detector used in the present invention.

FIG. 7 shows an example of the temperature characteristic of the output voltage of the temperature detector used in the present invention.

FIG. 8 shows an example of current density-luminance luminance characteristics of the organic electroluminescent element used in the present invention.

FIG. 9 is a circuit diagram example of a constant current drive power source for an organic electroluminescent device used in the present invention.

FIG. 10 is a block diagram of another drive circuit of the organic light emitting device of the present invention.

FIG. 11 is a block diagram of a drive circuit for an organic light emitting panel according to the present invention.

FIG. 12 is a block diagram of another drive circuit of the organic light emitting panel of the present invention.

FIG. 13 is an example of a timing chart for driving an organic electroluminescence panel of the present invention.

FIG. 14 is a schematic diagram of the characteristics of the gate voltage of the second TFT used in the organic electroluminescence panel drive circuit of the present invention with respect to the DATA pulse width.

FIG. 15 is an example of gate voltage-drain current characteristics of an a-Si TFT used in the organic electroluminescent panel drive circuit of the present invention.

[Explanation of symbols]

1 substrate 2 anode 3 hole transport layer 4 light emitting layer 5 cathode 6 glass substrate 7a TFT gate electrode, 7b storage capacitor electrodes 8, 8a, 8b SiNx insulating film 9, 9a, 9b i layer a-Si 10, 10a , 10b n ⁺ layer a-Si 11a source electrode 11b drain electrode 11c storage capacitor electrode 12 ITO pixel electrode 13 organic light emitting layer 20 organic electroluminescent device 21 driving power supply unit 22 temperature detector 23 A / D converter 24 ROM memory 25 D / A converter 26 Variable voltage amplifier 27 Thermistor 28 Fixed resistance 30 Subtractor 31 Inverting amplifier 32 Adder 40 Organic electroluminescence panel 41 Active matrix drive circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-125683 (JP, A) JP-A-62-157693 (JP, A) JP-A-51-144527 (JP, A) JP-A-3- 185491 (JP, A) Actually developed 58-100391 (JP, U) Temperature dependence of emission characteristics of organic EL devices, IEICE Technical Report (Technical Report), Vol. 90, No. 302, p. 19-24 Temperature Dependence in Emission Characteristics of an Organic EL Cell with-, Journal of the Electrochemistry, 1992. 139, no. 3, p. 641-643 (58) Fields investigated (Int.Cl. ⁷ , DB name) H05B 33/00-33/28 G09G 3/00-3/34

Claims (4)

(57) [Claims] 1. An organic electroluminescent device having an organic light-emitting layer sandwiched by an anode and a cathode on a substrate, and on the substrate
And an active matrix for driving the organic electroluminescent device.
And an active matrix circuit , wherein the active matrix circuit has a drive circuit for inputting a drive signal.
Polar SCAN and DATA electrodes, and current
SCA based on an output value from a temperature detector that has a COM electrode that is a supply electrode and is provided close to the organic electroluminescent device, and the temperature detection circuit.
For pulse width of N signal (input signal of SCAN electrode)
Pulse of DATA signal (input signal of DATA electrode)
An organic electroluminescence panel comprising means for determining a driving current of the organic electroluminescence device by changing a width . 2. An organic electroluminescence device comprising an organic electroluminescence device having an organic light emitting layer sandwiched between an anode and a cathode on a substrate, and an active matrix circuit for driving the organic electroluminescence device provided on the substrate. A panel, wherein the active matrix circuit is turned on / off according to a switching signal and charges and discharges a storage capacitor according to a light emission signal; and a discharge voltage from the storage capacitor. ON, OFF
And a second thin film transistor for controlling light emission and non-light emission of the organic electroluminescence element, a temperature detector provided in the vicinity of the organic electroluminescence panel, and an output from the temperature detection circuit. based on the value, the
Input signal pulse of the gate electrode of the first thin film transistor
The width of the source electrode of the first thin film transistor
By changing the pulse width of the input signal,
Controls the gate voltage of the film transistor, an organic electroluminescent panel, characterized in that it comprises means for determining a driving dynamic current of the organic light emitting diode. 3. The means for determining the drive current is digital.
The organic electroluminescent panel according to claim 1 or 2, which is a memory. 4. The method of claim 1 or 2, organic electroluminescent panel according means for determining the drive current is equal to or an analog arithmetic circuit.