Multi-mode backlight for electronic device

• US 6,496,236 B1
• Filed: 03/17/2000
• Issued: 12/17/2002
• Est. Priority Date: 03/17/2000
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Cole, James R, Dickie, James P
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US09/527,414
• Time in Patent Office: 1,005 Days
• Field of Search: 349/68, 349/61, 345/102, 362/27, 362/227
• US Class Current: 349/61
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night

Abstract

An electronic device has a display housing which includes a display panel and at least two light sources used to backlight the display panel. The at least two light sources are activated independently of each other to selectively increase or decrease the illumination of the display panel. A circuit is coupled to the at least two light sources. The circuit determines which of the at least two light sources is chosen such that the combined life of the at least two light sources is increased.

Claims

1. An electronic device, comprising:

a display housing including,

an electronic display panel, and

at least two light sources for backlighting the display panel, at least one of the light sources being activated independently of the other light source to selectively increase and decrease the illumination to the display panel; and

a circuit coupled to said at least two light sources, said circuit determining which of the at least two light sources is chosen wherein the combined life of the at least two light sources is increased.

2. The electronic device of claim 1 wherein at least one of the at least two light sources is a different sized light source from the remaining light sources.

3. The electronic device of claim 1 wherein the circuit selects the least cumulatively used light source to be activated.

4. The electronic device of claim 1 wherein said circuit includes current measuring circuitry to detect the cumulatively consumed current of each of the at least two light sources and wherein said circuitry selects the light source to be activated based on the least cumulatively consumed current for each light source.

5. The electronic device of claim 1 wherein said display housing further includes at least two light pipes for diffusing the respective light produced by each of the at least two light sources.

6. The electronic device of claim 5 wherein the at least two light pipes are stacked.

7. The electronic device of claim 6 wherein the at least two light pipes are wedged shaped.

8. The electronic device of claim 1 wherein said display housing further includes a single inverter and a set of switches coupling said at least two light sources to said single inverter.

9. The electronic device of claim 1 wherein said display housing further includes a set of inverters, each inverter of the set respectively coupled to each of said at least two light sources.

10. A display for an electronic device, comprising:

an electronic display panel;

at least two light sources for backlighting the display panel, at least one of the light sources being activated independently of the other light source to selectively increase and decrease the illumination to the display panel; and

a circuit coupled to said at least two light sources, said circuit determining which of the at least two light sources is chosen wherein the combined life of the at least two light sources is increased.

11. The display of claim 10 wherein at least one of the at least two light sources is a different sized light source from the remaining light sources.

12. The display of claim 10 wherein the circuit selects the least cumulatively used light source to be activated.

13. The display of claim 10 wherein the circuit includes current measuring circuitry to detect the cumulatively consumed current of each of the at least two light sources and wherein said circuitry selects the light source to be activated based on the least cumulatively consumed current by each light source.

14. The display of claim 10 further comprising at least two light pipes for diffusing the light produced by each of the at least two light sources.

15. The display of claim 14 wherein the at least two light pipes are stacked.

16. The display of claim 14 wherein the at least two light pipes are wedged shaped.

17. The display of claim 10 wherein said display further comprises a single inverter and a set of switches coupling said at least two light sources to said single inverter.

18. The display of claim 10 further comprising a set of inverters, each inverter of the set respectively coupled to each of said at least two light sources.

19. A method for extending the life of an electronic display having at least two light sources, the method comprising the steps of:

cumulatively measuring the amount of time each of said at least two light sources is activated;

waiting for a transition of the display illumination;

selecting the light source with the least cumulatively acquired time activated thereby creating a selected light source; and

activating the selected light source to illuminate the display.

20. An electronic device using the method of claim 19 to control the illumination of a display in the electronic device.

21. A method for extending the life of an electronic display having at least two light sources, the method comprising the steps of:

cumulatively measuring the amount of current consumed by each of said at least two light sources when activated;

waiting for a transition of the display illumination;

selecting the light source with the least cumulatively consumed current thereby creating a selected light source; and

activating the selected light source to illuminate the display.

22. An electronic device using the method of claim 21 to control the illumination of a display in the electronic device.