IP Library Granted Patent US 8,987,993
Granted Patent B2
US 8,987,993 · App. 14/188,864 · Granted Mar 24, 2015

Organic electroluminescence device

Inventors: Kohei Shoji (Kyoto, JP); Akimasa Maruo (Kyoto, JP)
Assignee: Rohm Co., Ltd.
H05B33/0896
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Quick Facts
Patent No.
US 8,987,993
App. No.
14/188,864
Granted
Mar 24, 2015
Kind
B2
Abstract

An organic EL device comprising: an organic EL element; a first transistor that controls a drive current of the organic EL element in accordance with a brightness adjustment voltage; and a temperature correction circuit that corrects the brightness adjustment voltage in accordance with a temperature; wherein the temperature correction circuit includes: a second transistor that has a same temperature characteristic as the first transistor; a resistor element that is connected to the second transistor; and an operational amplifier that controls the second transistor such that a predetermined reference voltage and a voltage across the resistor element become equal to each other; wherein the temperature correction circuit corrects the brightness adjustment voltage in accordance with an output from the operational amplifier.

Claims (28)

1. An organic EL device comprising:

an organic EL element;

a first transistor that controls a drive current of the organic EL element in accordance with a brightness adjustment voltage; and

a temperature correction circuit that corrects the brightness adjustment voltage in accordance with a temperature; wherein

the temperature correction circuit includes:

a second transistor that has a same temperature characteristic as the first transistor;

a resistor element that is connected to the second transistor; and

an operational amplifier that controls the second transistor such that a predetermined reference voltage and a voltage across the resistor element become equal to each other;

wherein the temperature correction circuit corrects the brightness adjustment voltage in accordance with an output from the operational amplifier.

2. The organic EL device according to claim 1 , further comprising:

a panel portion that is composed of a plurality of pixel circuits arranged in an array, and

a source driver that outputs a source voltage to the panel portion,

wherein the plurality of pixel circuits each include the organic EL element and the first transistor and receive an input of the source voltage as the brightness adjustment voltage.

3. The organic EL device according to claim 2 , wherein

the panel portion includes a plurality of dummy pixel circuits formed in a same pattern as the plurality of pixel circuits to surround the plurality of pixel circuits, and

at least one of the plurality of dummy pixel circuits is connected to the resistor element and the operational amplifier, and a transistor included in the dummy pixel circuit is used as the second transistor.

4. The organic EL device according to claim 3 , wherein

both a high-side dummy pixel circuit and a low-side dummy pixel circuit are equally connected to the operational amplifier.

5. The organic EL device according to claim 4 , further comprising a gradation voltage generation circuit that generates a plurality of gradation voltages that range from a white level during an all turned-on time to a black level during an all turned-off time, wherein

the source driver selects any one of the plurality of gradation voltages as the source voltage.

6. The organic EL device according to claim 5 , wherein

the temperature correction circuit uses two sets of the resistor element and the operational amplifier to decide the white level and a grey level during a half turned-on time, further decides the black level from the white level and the grey level.

7. The organic EL device according to claim 6 , wherein

a dummy pixel circuit connected to an operational amplifier for deciding the white level and a dummy pixel circuit connecting to an operational amplifier for deciding the grey level are disposed alternately.

8. The organic EL device according to claim 1 , further comprising a switch circuit that switches a number of the dummy pixel circuits connected to the operational amplifier.

9. The organic EL device according to claim 1 , wherein

the temperature correction circuit includes a reference voltage adjustment portion that finely adjusts the reference voltage in accordance with a register value.

10. An electronic apparatus comprising the organic EL device according to claim 1 .

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded May 2, 2014
From: SHOJI, KOHEI; MARUO, AKIMASA
To: ROHM CO., LTD.
Reel/Frame 032807/0976 →
Priority Claims (1)
JP 2013-034395 · Feb 25, 2013 · national
Continuity (1)
Related Publication 20140239846A1 · Aug 28, 2014