Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2000-02-28
2001-11-13
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S167000, C257S040000, C313S504000
Reexamination Certificate
active
06316879
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit for driving an organic electroluminescent (EL) circuit.
2. Description of the Related Art
An organic electroluminescent (EL) device comprising a transparent substrate on which an anode, at least organic layer, and a cathode are formed is disclosed, for example, in Japanese Patent Publication No. 32307/1994. The anode is made of a transparent conductive material. The organic layer consists either of an organic emissive layer or of a multilayer structure containing organic layers such as a hole injection layer. If necessary, a hole transport layer is added to the multilayer structure. The cathode is made of a conductive metal material.
In this organic EL device, a DC voltage of several volts to tens of volts is applied between the anode and the cathode to cause the organic layer to emit light. The organic EL device has the advantage that it can be driven at a lower driving voltage than other kinds of EL devices.
Generally, a driver circuit for this kind of organic EL device is composed of a constant-current circuit. A known circuit is shown in
FIG. 7
, where the organic EL device is indicated by
01
and has an anode
02
and a cathode
03
. A DC power supply supply
06
such as a battery is connected with the EL device
01
via a series combination of a transistor
04
and a resistor
05
. A series combination of a zener diode
07
and a resistor
08
is connected in parallel with the DC power supply
06
. The neutral point of this series circuit is connected with the positive terminal of an operational amplifier
09
. The negative terminal of the amplifier
09
is connected with the junction of the amplifier
09
and the transistor
04
. This driver circuit limits the current supplied to the organic EL device
01
to a certain value at all times.
This driver circuit for an organic EL device needs numerous electronic components including transistor
04
and operational amplifier
09
. Where numerous display segments are formed on the anode
02
, or where plural anodes
02
and plural cathodes
03
intersect to form a matrix structure, it is necessary to prepare the aforementioned electronic components for each of the electrodes. This increases the number of components, leading to an increase in the cost.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an organic. EL device driver circuit free of the foregoing problems.
A DC power supply (
4
) is connected with an organic electroluminescent (EL) device (
1
) having an anode (
2
) and a cathode (
3
). Thus, a driver circuit that is simple and made up of an unincreased number of components is obtained.
The organic EL device (
1
) and a resistor (
5
) are electrically connected to form a series circuit. The DC power supply (
4
) is connected with this series circuit. In particular, the resistor (
5
) is connected with the anode (
2
) of the organic EL device (
1
) to form the series circuit with which the DC power supply (
4
) is connected.
In this way, the driver circuit for the organic EL device is simple in structure and made up of an unincreased number of components. Furthermore, the driver circuit is insusceptible to ambient temperature variations.
Other objects and features of the invention will appear in the course of the description thereof, which follows.
REFERENCES:
patent: 4538507 (1985-09-01), VanSlyke et al.
patent: 5593788 (1997-01-01), Shi et al.
patent: 5886474 (1999-03-01), Asai et al.
patent: 5965901 (1999-10-01), Heeks et al.
patent: 6043510 (2000-03-01), Kawamoto
patent: 6097139 (2000-08-01), Tuck et al.
patent: 2-10693 (1990-01-01), None
patent: 5-205873 (1993-08-01), None
patent: 5-307996 (1993-11-01), None
patent: 6-32307 (1994-04-01), None
patent: 7-122361 (1995-05-01), None
patent: 9-16123 (1997-01-01), None
McDermott & Will & Emery
Nippon Seiki Co. Ltd.
Philogene Haissa
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