Apparatus for lighting a passive display

• US 4,453,200 A
• Filed: 07/20/1981
• Issued: 06/05/1984
• Est. Priority Date: 07/20/1981
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Trcka, James S., Thorkildson, Robert J.
• Primary Examiner(s): Nelson, Peter A.
• Application Number:
  US06/284,904
• Time in Patent Office: 1,051 Days
• Field of Search: 362/28, 362/29, 362/30, 362/31, 362/318, 362/307, 362/311, 362/341, 362/355-356, 362/362
• US Class Current: 362/603
• 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: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133616 Front illuminating devices

Abstract

Apparatus for front lighting a display includes a light distributing wedge, spaced from the front of the display to be lighted, through which the display can be viewed. A light source is provided aside the wedge to direct light to an inter space between the wedge and the display. A reflective surface is provided at the wide end of the wedge to reflect light incident upon it. Thus, light from the light source is directed onto the display through various reflecting and refracting paths, including directly onto the display from the light source, reflected from the interior surface of the wedge onto the display, and refracted and reflected within the wedge to be emitted in the direction of the display.

Claims

1. A front-lighted display system comprising:

a display having a front surface from which visual indications can be viewed;

a transparent light-distributing wedge having a narrow end and a wide end containing a reflective surface thereon, said wedge being spaced from the front surface of the display to form a space between the wedge and display and positioned such that the display can be viewed through said wedge; and

means positioned adjacent the narrow end of said wedge and display and coupled for introducing light into the space between said wedge and display such that a portion of said light in said space is directed upon said wedge and is reflected onto said display, a portion of said light in said space is directed upon said wedge and is internally reflected within the wedge until it exits the wedge and illuminates said display, and a portion of said light in said space directly illuminates said display, whereby the display is illuminated bi-directionally resulting in a more uniformly lighted display.

2. The apparatus of claim 1 further comprising means adjacent to said means for introducing light for reflecting and concentrating said light into the space between said wedge and display.

7. The apparatus of claim 1 wherein said display is a twisted nematic liquid crystal display.

3. An apparatus for front-lighting a passive, planar display comprising:

a planar display;

a transparent planar element coupled to said display and spaced therefrom such that said display is viewed through said planar element, said planar element having a wedge shape with a broad end and a narrow end;

reflective means positioned adjacent said broad end of said planar element to reflect light internally within said planar element;

means positioned adjacent to the narrow end of said wedge shaped planar element and coupled to said planar element and said display for introducing light into the space between said wedge shaped planar element and said display such that a portion of said light in said space is directed upon said wedge shaped planar element and is reflected onto said display, a portion of the light in said space is directed upon said wedge shaped planar element and is internally reflected within the wedge shaped planar element until it exits the wedge shaped planar element and illuminates said display, and a portion of said light in said space directly illuminates said display, whereby the display is illuminated bi-directionally resulting in a more uniformly lighted display; and

light reflector means coupled to said means for introducing light for reflecting light into the space between said wedge shaped planar element and display.

4. The apparatus of claim 3 wherein said means for introducing light is at least one incandescent lamp.

8. The apparatus of claim 3 wherein said planar display is a twisted nematic liquid crystal display.

5. An apparatus for front lighting a display comprising:

a transparent light distributing wedge having a narrow end and a broad end and a means adjacent said broad end for reflecting light internally within said wedge;

means coupled to said wedge for spacing said wedge from a display and positioning said wedge such that a display can be viewed through said wedge; and

means coupled adjacent the narrow end of said wedge for introducing light into the space between said wedge and display when said wedge is positioned adjacent a display such that a portion of said light in said space is directed upon said wedge and is reflected onto said display, a portion of light in said space is directed upon said wedge and is internally reflected within the wedge until it exits the wedge and illuminates said display, and a portion of said light in said space directly illuminates said display, whereby the display is illuninated by-directionally resulting in a more uniformly lighted display.

6. The apparatus of claim 5 wherein said wedge has a first planar surface and a second inclined planar surface forming opposed surfaces of said wedge, said planar surfaces being bounded by opposed planar surfaces forming a narrow end and a broad end of said wedge, said wedge further being positioned with respect to said means for introducing light such that said inclined planar surface is positioned to form the space between said wedge and display, and said first planar surface forms the surface through which a display is viewed.