Backlighting apparatus

• US 4,975,808 A
• Filed: 10/02/1989
• Issued: 12/04/1990
• Est. Priority Date: 10/02/1989
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kaschke, Kevin D., Bond, David L.
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Cole, Richard R.
• Application Number:
  US07/415,741
• Time in Patent Office: 428 Days
• Field of Search: 362/31, 362/26, 362/27, 362/327, 362/330, 362/339
• US Class Current: 362/609
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G09F 2013/1831 using more than one light source

Abstract

Improved backlighting apparatus evenly illuminates positive and negative LCDs under all ambient lighting conditions. Incandescent lamps (301-304) provide light for distribution by a light pipe (101). The bottom of the light pipe (101) is selectively painted white to reflect light to the top of the light pipe (101) while the unpainted areas reflect light internal to the light pipe (101), controlling hot and dim spots. The corners of the light pipe (101) near the lamps (301-304) are dual angled to reflect the light into the center of the display. The burn-out of a lamp (301-304) will not substantially affect the even lighting capabilities of the apparatus.

Claims

1. Apparatus for backlighting a liquid crystal display, comprising:

(a) substantially transparent means for distributing light having sides, a top, and a bottom, at least one side of the sides having at least one recess;

(b) at least one light source, positioned in the at least one recess, for providing the light;

(c) first reflecting means for changing a path of the light exiting at least one side of the means for distributing light;

(d) second reflecting means, positioned in at least one plane around the at least one light source, for reflecting the light;

(e) a diffuse reflecting material disposed upon the bottom of the means for distributing light; and

(f) a segment of the at least one side, between the at least one recess and a corner of the transparent means for distributing light, having a plurality of angles for reflecting the light.

2. The apparatus of claim 1 wherein the at least one light source is an incandescent light bulb.

3. The apparatus of claim 1 wherein the means for distributing light is a flat light pipe comprised of a substantially transparent material.

4. The apparatus of claim 3 wherein the substantially transparent material is an acrylic material.

5. The apparatus of claim 1 wherein the top, a selective part of the bottom, and the sides of the means for distributing light are smooth.

6. The apparatus of claim 1 wherein the diffuse reflecting material disposed upon the bottom of the means for distribution light is white paint.

7. The apparatus of claim 1 wherein the diffuse reflective material is disposed such that the at least one light source provide evenly distributing light.

8. Apparatus for backlighting a liquid crystal display, comprising:

(a) substantially transparent means for distributing light having sides, a top, and a bottom, at least one side of the sides having at least one recess;

p1 (b) at least one light source, positioned in the at least one recess, for providing the light;

(c) a diffuse reflecting material disposed upon the bottom of the means for distributing light; and

(d) a segment of the at least one side, between the at least one recess and a corner of the transparent means for distributing light, having a plurality of angles for reflecting the light.

9. The apparatus of claim 8 wherein the at least one light source is an incandescent light bulb.

10. The apparatus of claim 8 wherein the means for distributing light is a flat light pipe comprised of a substantially transparent material.

11. The apparatus of claim 10 wherein the substantially transparent material is an acrylic material.

12. The apparatus of claim 8 wherein the top, a selective part of the bottom, and the side of the means for distributing light are smooth.

13. The apparatus of claim 8 wherein the diffuse reflecting material disposed upon the bottom of the means for distributing light is white paint.

14. Apparatus for backlighting a liquid crystal display, comprising:

(a) a flat, substantially transparent means for distributing light, having four sides, wherein a first and a second opposing side each have a recess, each recess having at least one light source positioned therein for providing the light, the first and second opposing sides each having a plurality of angles between a corner of the means for distributing light and the recess, wherein light emitted from a light source of the at least one light source is reflected off the plurality of angles to substantially evenly distribute the light within the means for distributing light;

(b) a first reflecting surface positioned on a third side of the means for distributing light and a second reflecting surface positioned on a fourth side of the means for distributing light, such that the light exiting the third and fourth sides is reflected into the means for distributing light;

(c) a third reflecting surface, for reflecting the light, positioned in at least one plane around the at least one light source on the first opposing side;

(d) a fourth reflecting surface, for reflecting the light, positioned in at least one plane around the at least one light source on the second opposing side; and

(e) a diffuse reflecting material disposed on a bottom of the light pipe for diffusing light striking the bottom of the light pipe, the reflecting material disposed in such a manner as to substantially evenly distribute the light from the at least one light source.

15. The apparatus of claim 14 wherein the at least one light source is at least one incandescent light bulb.

16. The apparatus of claim 14 wherein the means for distributing light is a flat light pipe comprised of a substantially transparent material.

17. The apparatus of claim 16 wherein the substantially transparent material is an acrylic material.

18. The apparatus of claim 14 wherein the top, a selective part of the bottom, and the sides of the means for distributing light are smooth.

19. A communication apparatus, the apparatus comprising:

(a) transmitting means;

(b) receiving means; and

(c) a liquid crystal display (LCD) module for displaying data, the module comprising;

an LCD; and

an LCD backlighting apparatus, comprising;

substantially transparent means for distributing light having sides, a top, and a bottom, at least one side of the sides having at least one recess;

at least one light source, positioned in the at least one recess, for providing the light;

a diffuse reflecting material disposed upon the bottom of the means for distributing light; and

a segment of the at least one side, between the at least one recess and a corner of the transparent means for distributing light, having a plurality of angles for reflecting the light.