Energy saving backlight device

• US 6,255,781 B1
• Filed: 07/29/1999
• Issued: 07/03/2001
• Est. Priority Date: 08/26/1998
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tsumura, Toshiyuki
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US09/363,724
• Time in Patent Office: 705 Days
• Field of Search: 315/169.3, 315/169.1, 345/102, 345/76, 345/204, 313/495, 313/502, 313/506, 313/509
• US Class Current: 315/169.1
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A backlighting element 13 includes an EL panel for illuminating the back of a display unit 11, to thereby provide a good viewing. A control unit 16 sends an instruction to a backlight driver 14, and intermittently drives the backlighting element 13 at appropriate timings, or temporarily stops the driving of the backlighting element 13 in synchronism with operation timings of a radio processing unit 17. The radio processing unit is adversely affected by noise generated when the backlighting element is operated. A light storage member is provided on the backlighting element 13 or in its vicinity. With provision of the light storage member, the lighting time of the backlighting element is reduced. When the backlighting element is lit off, the user is not put to inconvenience.

Claims

1. A backlight device comprising:

a backlighting element with an EL panel providing a light emitting means for illuminating the back of a visually presenting means;

at least one light emitting section making up the backlighting element;

upper and lower electrodes forming each of said light emitting sections;

at least one set of said upper and lower electrodes forming the light emitting section of said backlighting element, formed so that said light emitting section is disposed occupying a less than whole part of an area defined by a configuration of said light emitting means in said EL panel.

2. The backlighting element according to claim 1, wherein

said light emitting section takes a form selected from a group of a lattice, a stripe and a slant lattice.

3. The backlighting element according to claim 1, wherein

visually presenting means which is illuminated is a liquid crystal panel constituting a display unit of a device, and

said light emitting section is formed in corresponding to shape of display lines of said liquid crystal display panel or display units consisting of display characters.

4. The backlighting element according to claim 1, wherein

said visually presenting means which is illuminated is a liquid crystal panel constituting a display unit of a device,

said light emitting section is divided into a plurality of light emitting segments corresponding to display lines of said liquid crystal display panel or display units consisting of display characters, and

said plurality of light emitting segments are selectively driven.

5. The backlight device according to claim 1 further comprising:

a light diffusing means for diffusing light emitted from said light emitting section.

6. The backlight device according to claim 5, wherein

said light diffusing means is formed by interposing a sheet or plate member having a light diffusing function between said backlighting element and an illuminated member, by coating the surface of said backlighting element with light diffusing material, or by coupling an optical member having light diffusing function to said backlighting element or an illuminated member.

7. The backlight device according to claim 5, further comprising:

a light storage member capable of storing backlight from said light emitting means of said backlighting element or natural light to spontaneously emit light.

8. The backlight device according to claim 7, wherein

said light storage means is formed by interposing a sheet or plate member with light storage material between said backlighting element and an illuminated member, by coating the surface of said backlighting element with light storage material, or by use of said backlighting element with light storage material.

9. The backlighting device according to claim 5, wherein

said visually presenting means is a liquid crystal panel constituting a display unit of a device, and

said light emitting section of said backlighting element is divided into a plurality of segments corresponding to display lines of said liquid crystal display panel or display units consisting of display characters,

said backlighting device further comprising drive control means for selectively driving said plurality of segments of said light emitting section to locally light on and off said light emitting section.