Lighting device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Jun Koyama
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Abstract
To provide a lighting device in which the luminance of an EL element is maintained even when the EL element deteriorates so that degradation of the lighting device is reduced, the lighting device includes a surface light source portion including an organic EL element, and a control circuit portion provided in a base portion. The control circuit portion counts a lighting time of the organic EL element and controls the luminance of the organic EL element in accordance with the lighting time. Accordingly, the lighting device in which the luminance of an EL element is maintained regardless of degradation of the EL element so that degradation of the lighting device is reduced can be provided.
Claims25
A lighting device comprising:
- a surface light source portion comprising:
- a light-emitting element comprising;
- a first electrode;
- a light-emitting layer over the first electrode;
- and
- a second electrode over the light-emitting layer;
- an insulating film over the light-emitting element;
- a first wiring over the insulating film;
- and
- a second wiring over the insulating film;
- and
- a control circuit portion in a base portion,
- wherein the control circuit portion comprises a variable current source circuit configured to supply a current to the light-emitting element,
- wherein the light-emitting layer comprises an organic compound,
- wherein the first wiring is electrically connected to the first electrode, and
- wherein the second wiring is electrically connected to the second electrode.
A lighting device comprising:
- a surface light source portion comprising:
- a light-emitting element comprising:
- a first electrode;
- a light-emitting layer over the first electrode;
- and
- a second electrode over the light-emitting layer;
- and
- an insulating film over the light-emitting element;
- and
- a control circuit portion in a base portion,
- wherein the control circuit portion comprises a variable current source circuit configured to supply a current to the light-emitting element,
- wherein the light-emitting layer comprises an organic compound,
- wherein the insulating film compromises an opening, and
- wherein part of the first electrode and part of the second electrode are each exposed in the opening.
A lighting device comprising:
- a surface light source portion comprising:
- a substrate comprising a first opening in a center of the substrate;
- a light-emitting element over the substrate, the light-emitting element comprising:
- a first electrode over the substrate;
- a light-emitting layer over the first electrode;
- and
- a second electrode over the light-emitting layer;
- and
- an insulating film over the light-emitting element;
- and
- a control circuit portion in a base portion,
- wherein the control circuit portion comprises a variable current source circuit configured to supply a current to the light-emitting element,
- wherein the light-emitting layer comprises a an organic compound,
- wherein the insulating film comprises a second opening, and
- wherein part of the first electrode and part of the second electrode are each exposed in the second opening.
Dependencies are inferred from the claim text.