Electroluminescent lighting system

• US 7,246,912 B2
• Filed: 10/03/2003
• Issued: 07/24/2007
• Est. Priority Date: 10/03/2003
• Status: Expired due to Fees

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Burger, Victor, Van Walstijn, Bartholomeus Gerardus Gosewinus
• Primary Examiner(s): O'Shea; Sandra
• Assistant Examiner(s): Truong; Bao Q.
• Application Number:
  US10/678,350
• Publication Number:
  US 20050073829A1
• Time in Patent Office: 1,390 Days
• Field of Search: 362/84, 362/34, 362/173, 362/20, 313/463, 313502-504, 313/506, 313/498, 349/69, 315/169.3, 315/169.1, 315/169.2, 315/169.4, 345/76, 345/77, 345/82, 345/102
• US Class Current: 362/84
• CPC Class Codes: H04M 1/0283 for providing a decorative aspect, e.g. customization of casings, exchangeable faceplate
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H05B 44/00 Circuit arrangements for operating electroluminescent light sources for operating light emitting diodes H05B45/00
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Electroluminescent panels for use in battery operated devices include a driver circuit and a plurality of panel regions having a capacitance. Each panel region has a substitute capacitor with a capacitance substantially equal to the capacitance of the panel region concerned. The driver circuit switches between the panel region and the substitute capacitor, switching the panel region on and off. The capacitance of the load on the driver circuit does not change. The electroluminescent panels can have an elimination layer that eliminates noise produced by the emission layer in operation caused by changes in emission layer thickness. The elimination layer is added to the panel and operated in phase opposition to the emission layer. Changes in layer thickness occurring in operation in the emission layer are offset by changes in thickness in the elimination layer. Thus, the overall thickness of the panel is constant.

Claims

1. A lighting system comprising:

a driver circuit including a source of AC voltage,

an electroluminescent panel with a plurality of panel regions configured to emit visible light when AC voltage is applied thereto,

each panel region having a given capacitance and being selectively connectable to the source of AC voltage, wherein each panel region is configured to maintain a substantially constant capacitance load on the source of AC voltage,

a substitute capacitor layer associated with each panel region, the substitute capacitor layer having a capacitance that is substantially equal to the capacitance of the associated panel region,

the substitute capacitor layer being connected to the source of AC voltage when the associated panel region is not connected to the source of AC power and vice versa.

2. The lighting system according to claim 1, wherein the driver circuit comprises a plurality of current flow control devices coupled to the electrodes of the panel regions and to the electrodes of the substitute capacitor layer.

3. The lighting system according to claim 2, wherein the current flow control devices comprise switches that alternately charge the panel sections and the associated substitute capacitor layer.

4. The lighting system according to claim 1, wherein the driver circuit further comprises a controller configured to control the current flow control devices.

5. The lighting system according to claim 1, wherein the panel regions and the substitute capacitors layer are formed in a single thin film.

6. The lighting system according to claim 5, wherein the panel regions comprise;

an emission layer between a transparent front electrode and a second electrode, and

the substitute capacitor layer is between the second electrode and a rear electrode.

7. The lighting system according to claim 1, wherein the AC voltage source is a battery driven step up converter.

8. A thin film electroluminescent panel comprising;

an emission layer arranged in between a transparent front electrode and a second electrode,

a substitute capacitor layer arranged between the second electrode and a rear electrode, the substitute capacitor layer having a capacitance that is substantially equal to a capacitance of the panel, and a source of AC voltage connected to the substitute capacitor, the source of AC voltage being connected to the substitute capacitor when the panel is not connected to the source of AC power and vice versa.

9. The thin film electroluminescent panel according to claim 8, wherein the substitute capacitor layer and the emission layer are formed by one and the same electrolytic material.

10. The thin film electroluminescent panel according to claim 8, wherein the electroluminescent panel comprises a plurality of panel regions each having an emission layer and a substitute capacitor layer, each panel region having a given capacitance and being selectively connectable to the source of AC voltage,

a substitute capacitor associated with each panel region, the substitute capacitor having a capacitance that is substantially equal to the capacitance of the associated panel region,

the substitute capacitor being connected to the source of AC voltage when the associated panel region is not connected to the source of AC power and vice versa.

11. The thin film electroluminescent panel of claim 8 further comprising a switch alternately connected between the transparent front electrode and ground, and the rear electrode and ground.

12. A lighting system comprising:

a driver circuit including a source of AC voltage;

an electroluminescent panel region configured to emit visible light when AC voltage is applied thereto;

the panel region having a given capacitance and being selectively connectable to the source of AC voltage, wherein the panel region is configured to maintain a substantially constant capacitance load on the source of AC voltage,;

a substitute capacitor associated with the panel region, the substitute capacitor having a capacitance that is substantially equal to the capacitance of the panel region;

the substitute capacitor being connected to the source of AC voltage when the panel region is not connected to the source of AC power and vice versa.