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US 6,788,003 B2Granted

Light emitting device

AssigneeSemiconductor Energy Laboratory Co., Ltd.

InventorsKazutaka Inukai, Tomoyuki Iwabuchi

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Abstract Drawings Claims Description

Abstract

A light emitting device is provided, in which a change of luminance of an OLED is suppressed and a desired color display can be stably performed even if an organic light emitting layer is somewhat deteriorated or an environmental temperature is varied. Separately from a pixel portion for displaying an image, a pixel portion for measuring a driving current of the OLED is provided in the light emitting device. The driving current is measured in the pixel portion for measuring the driving current of the OLED, and a value of the voltage supplied to the above two pixel portions from a variable power supply is corrected such that the measured driving current has a reference value. With the above-described structure, a reduction of the luminance accompanied with the deterioration of the organic light emitting layer can be suppressed. As a result, a clear image can be displayed.

Claims25

Dependent claims

Claim 1A light emitting device · 144 words3 dependent Claim 2A light emitting device · 169 words3 dependent Claim 3A light emitting device · 202 words3 dependent Claim 4A light emitting device · 194 words3 dependent Claim 5A light emitting device · 199 words3 dependent Claim 6A light emitting device · 201 words3 dependent Claim 8A light emitting device · 139 words9 dependent Claim 9A light emitting device · 158 words9 dependent Claim 11A light emitting device · 109 words8 dependent Claim 15A light emitting device · 149 words6 dependent Claim 16A light emitting device · 153 words6 dependent Claim 17A light emitting device · 158 words6 dependent Claim 22A light emitting device · 106 words2 dependent Claim 23A light emitting device · 52 words2 dependent

A light emitting device comprising:

a first pixel portion having a first OLED;
a second pixel portion having a second OLED;
first means for measuring a current flowing in the second OLED;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to the second OLED for making the value of the current flowing in the second OLED close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal,
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal, and
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED.

6 more elements

A light emitting device comprising:

a first pixel portion provided with a plurality of first pixels each having a first OLED;
a second pixel portion provided with a plurality of second pixels each having a second OLED;
first means for measuring the total of a current flowing in all the second OLEDs;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to all the second OLEDs for making the value of the total of the current flowing to all the second OLEDs close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal.
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal, and
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED.

6 more elements

A light emitting device comprising:

a first pixel portion provided with a plurality of first pixels each having a first OLED;
a second pixel portion provided with a plurality of second pixels each having a second OLED;
first means for measuring the total of a current flowing in all the second OLEDs;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to all the second OLEDs for making the value of the total of the current flowing in all the second OLEDs close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal,
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal,
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED, and
wherein the voltage to be corrected is changed with a constant size every time when the difference between the measured current value and the reference current value is changed with a constant width.

7 more elements

A light emitting device comprising:

a first pixel portion provided with a plurality of first pixels each having a first OLED;
a second pixel portion provided with a plurality of second pixels each having a second OLED;
first means for measuring the total of a current flowing in all the second OLEDs;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to all the second OLEDs for making the value of the total of the current flowing in all the second OLEDs close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal,
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal,
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED, and
wherein a specific image is displayed on the second pixel portion when the total of the current flowing in all the second OLEDs is measured.

7 more elements

A light emitting device comprising:

a first pixel portion provided with a plurality of first pixels each having a first OLED;
a second pixel portion provided with a plurality of second pixels each having a second OLED;
first means for measuring the total of a current flowing in all the second OLEDs;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to all the second OLEDs for making the value of the total of the current flowing in all the second OLEDs close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signa,.
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal,
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED, and
wherein the reference current value differs depending on an image displayed on the second pixel portion when the total of the current flowing in all the second OLEDs is measured.

7 more elements

A light emitting device comprising:

a first pixel portion provided with a plurality of first pixels each having a first OLED and at least one first TFT, the first TFT controlling light emission of the first OLED;
a second pixel portion provided with a plurality of second pixels each having a second OLED and at least one second TFT, the second TFT controlling light emission of the second OLED;
first means for measuring the total of a current flowing in all the second OLEDs;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to all the second OLEDs for making the value of the total of the current flowing in all the second OLEDs close to the reference current value based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal,
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal, and
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED.

6 more elements

A light emitting device comprising:

a display pixel portion having a first OLED;
a monitor pixel portion having a second OLED;
a variable power supply;
an ammeter for measuring a current flowing in the second OLED;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to the second OLED for making the value of the current flowing in the second OLED close to the reference current value by controlling the variable power supply,
wherein the display pixel portion is input with a display video signal,
wherein the monitor pixel portion is input with a monitor video signal which is distinct from the display video signal, and
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED.

6 more elements

A light emitting device comprising:

a display pixel portion having a plurality of first OLEDs;
a monitor pixel portion having a plurality of second OLEDs;
an ammeter for measuring the total of a current flowing in all the plurality of second OLEDs;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to all the plurality of second OLEDs for making the value of the total of the current flowing in all the plurality of second OLEDs close to the reference current value by controlling a variable power supply,
wherein the display pixel portion is input with a display video signal,
wherein the monitor pixel portion is input with a monitor video signal which is distinct from the display video signal, and
wherein a voltage applied to the plurality of first OLEDs is kept at the same level as the voltage applied to the plurality of second OLEDs.

5 more elements

A light emitting device comprising:

a first OLED;
a second OLED;
a first variable power supply;
a second variable power supply;
an ammeter for measuring a current flowing in the second OLED;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to the second OLED for making the value of the current flowing in the second OLED close to the reference current value by controlling the second variable power supply,
wherein a voltage applied to the first OLED is kept at the same level as the voltage applied to the second OLED by the first variable power supply.

5 more elements

A light emitting device comprising:

a plurality of first OLEDs;
a plurality of second OLEDs;
an ammeter for measuring the total of a current flowing in all the plurality of second OLEDs;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to all the plurality of second OLEDs for making the value of the total of the current flowing in all the plurality of second OLEDs close to the reference current value by controlling a variable power supply,
wherein a voltage applied to the plurality of first OLEDs is kept at the same level as the voltage applied to the plurality of second OLEDs, and
wherein the voltage to be corrected is changed with a constant size every time when the difference between the measured current value and the reference current value is changed with a constant width.

4 more elements

A light emitting device comprising:

a first pixel portion having a plurality of first OLEDs;
a second pixel portion having a plurality of second OLEDs;
an ammeter for measuring the total of a current flowing in all the plurality of second OLEDs;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to all the plurality of second OLEDs for making the value of the total of the current flowing in all the plurality of second OLEDs close to the reference current value by controlling a variable power supply,
wherein a voltage applied to the plurality of first OLEDs is kept at the same level as the voltage applied to the plurality of second OLEDs, and
wherein a specific image is displayed on the second pixel portion when the total of the current flowing in all the plurality of second OLEDs is measured.

4 more elements

A light emitting device comprising:

a first pixel portion having a plurality of first OLEDs;
a second pixel portion having a plurality of second OLEDs;
an ammeter for measuring the total of a current flowing in all the plurality of second OLEDs;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to all the plurality of second OLEDs for making the value of the total of the current flowing in all the plurality of second OLEDs close to the reference current value by controlling a variable power supply,
wherein a voltage applied to the plurality of first OLEDs is kept at the same level as the voltage applied to the plurality of second OLEDs, and
wherein the reference current value differs depending on an image displayed on the second pixel portion when the total of the current flowing in all the plurality of second OLEDs is measured.

4 more elements

A light emitting device comprising:

a first pixel portion having a first OLED;
a second pixel portion having a second OLED;
first means for measuring a current flowing in the second OLED;
second means for comparing the measured current value and a reference current value;
and
third means for correcting a voltage applied to the first and second OLEDs based on a difference between the measured current value and the reference current value,
wherein the first pixel portion is input with a display video signal, and
wherein the second pixel portion is input with a monitor video signal which is distinct from the display video signal.

5 more elements

A light emitting device comprising:

a first OLED;
a second OLED;
a variable power supply;
an ammeter for measuring a current flowing in the second OLED;
and
a correction circuit for comparing the measured current value and a reference current value and correcting a voltage applied to the first and second OLEDs.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/060,709Filed 29 Jan 2002
Priority: JP 2001-01965129 Jan 2001
Published: US 2002/0125831 A112 Sep 2002
Granted: 7 Sep 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

G09G 3/3266
Organic, e.g. using organic light-emitting diodes [OLED]: details of drivers for scan electrodes
G09G 3/3233
Using an active matrix: with pixel circuitry controlling the current through the light-emitting element
G09G 3/3275
Organic, e.g. using organic light-emitting diodes [OLED]: details of drivers for data electrodes
G09G 3/3283
Details of drivers for data electrodes: in which the data driver supplies a variable data current for setting the current through, or the voltage…

Family

US 2002/0125831 A1Pre-grant publication · published 12 Sep 2002
US 6,788,003 B2This patent

From the US filing history. Foreign family members aren’t listed.

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