Illuminated LCD apparatus

• US 5,477,422 A
• Filed: 10/27/1994
• Issued: 12/19/1995
• Est. Priority Date: 05/22/1992
• Status: Expired due to Term

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Smith, Dave, Hooker, Guy
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Cariaso, Alan B.
• Application Number:
  US08/330,099
• Time in Patent Office: 418 Days
• Field of Search: 362/26, 362/27, 362/29, 362/30, 362/31, 362/290, 362/330, 362/237, 362/240, 362/242, 362/248, 359/48, 359/49, 359/50
• US Class Current: 362/29
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A back-lit LCD apparatus comprises a LCD (1), one or more LEDs (3) (or other light sources), and a plate-like light guide (2) behind the LCD (1). An attenuating member (5) is included in front or behind the light guide (5). In the former case the attenuating member (5) is formed as a sheet of reflective material on which is printed a pattern of non-reflective dots for reducing the intensity of light reaching portions of the LCD nearest to the light source. In the latter case the attenuating member (5) is transparent and the dots are either opaque or reflective. The size and frequency of the dots may be varied to adjust the level of attenuation. Also, the pattern of dots may be graduated to provide progressively less attenuation as the distance from the LEDs increases.

Claims

1. An illuminated liquid crystal display apparatus, comprising:

a liquid crystal display,

a plurality of point light sources generally located behind the liquid crystal display,

a light guide comprising a transparent plate-like member having side faces disposed behind the liquid crystal display for distributing light from the light sources over an area of the liquid crystal display, and

light-attenuating means disposed adjacent the light guide and including a pattern of dots defining a distinct individual portion proximate each one of the point light sources and spaced from one another for reducing the intensity of light reaching portions of the liquid crystal display nearest to the individual point light sources.

2. An illuminated liquid crystal display apparatus as claimed in claim 1, wherein the light-attenuating means comprises a reflective sheet and the dots provided thereon are non-reflective.

3. An illuminated liquid crystal display apparatus as claimed in claim 1, wherein the light-attenuating means comprises a reflective layer coated on the light guide, and the dots provided therein are non-reflective.

4. An illuminated liquid crystal display apparatus as claimed in claim 1, wherein the light attenuating means comprises a translucent sheet and the dots provided thereon are non-translucent.

5. An illuminated liquid crystal display apparatus as claimed in claim 1 wherein the light attenuating means comprises a pattern of light-blocking dots.

6. An illuminated liquid crystal display apparatus as claimed in claim 1, wherein the pattern of dots is graduated whereby the intensity of light reaching the liquid crystal display is reduced less as the distance from the light source increases.

7. An illuminated crystal display apparatus as claimed in claim 6, wherein the plurality of light sources are disposed adjacent at least one of the side faces of the light guide, and the pattern of dots is graduated linearly.

8. An illuminated guide crystal display apparatus as claimed in claim 6, wherein the point light sources are provided behind the light guide, and the pattern of dots is graduated radially around the areas of the individual light sources.