Removable backlighting assembly for flat panel display subsystem

• US 5,896,119 A
• Filed: 06/27/1995
• Issued: 04/20/1999
• Est. Priority Date: 06/27/1995
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Evanicky, Daniel E., Keely, Leroy Bertrand, Siefert, Steven
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): NGUYEN, FRANCIS N
• Application Number:
  US08/495,213
• Time in Patent Office: 1,393 Days
• Field of Search: 345/102, 345/87, 345/905, 353/122, 362/31, 362/216, 349/59
• US Class Current: 345/87
• 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: G02B 6/0085 Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: G02B 6/0088 of the light guide or other optical sheets in the package
• CPC Class Codes: G02B 6/009 of the light source in the package G02B6/0021 takes precedence
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133627 Projection-direct viewing
• CPC Class Codes: G06F 1/16 Constructional details or arrangements
• CPC Class Codes: G06F 1/1601 Constructional details related to the housing of computer displays, e.g. of CRT monitors, of flat displays constructional details related to flat displays integrated in a portable computer, e.g. laptop, handheld computer G06F1/1637; constructional details related to television receivers H04N5/64
• CPC Class Codes: G06F 1/1616 with folding flat displays, e.g. laptop computers or notebooks having a clamshell configuration, with body parts pivoting to an open position around an axis parallel to the plane they define in closed position
• CPC Class Codes: G06F 1/1637 Details related to the display arrangement, including those related to the mounting of the display in the housing
• CPC Class Codes: G06F 2200/1612 Flat panel monitor
• CPC Class Codes: G09G 2340/0492 Change of orientation of the displayed image, e.g. upside-down, mirrored
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: Y10S 345/905 Display device with housing structure

Abstract

A light distributing removable door assembly (and elements thereof) for a back-lit flat panel display subsystem wherein the subsystem is for direct viewing as a monitor and having overhead projection capability. The removable door assembly provides for back-lighting via a light pipe for direct viewing when installed in the subassembly. When the door assembly is removed, the active matrix LCD is semi-transparent and can be placed over the imaging screen (viewing side down) of an overhead projector such that the LCD color image can be thus projected. The lamps that provide the back-lighting remain within the display subsystem when the door is removed and a unique optical coupling is provided between the lamps and a light pipe within the door. A specialized bi-directional light extraction pattern is used on a light pipe of the removable door to provide effective and uniform light distribution over the LCD image. A clamping mechanism is also described within the removable door for securing the layers used in the door assembly. The clamping mechanism allows a reduction in a size of a junction formed between the lighting units of the subsystem and the removable door assembly.

Claims

1. A display screen comprising:

a transparent flat panel display screen;

a pair of light sources disposed along a first edge and a second edge, respectively, of said flat panel display screen for providing light wherein said first edge is opposite said second edge;

a light pipe positioned to receive said light emitted from said pair of light sources and for uniformly distributing said light over said flat panel display screen; and

a bi-directional light extraction pattern of dots disposed on one surface of said light pipe for extracting light from said light pipe to uniformly distribute to said flat panel display screen, wherein said light extraction pattern comprises;

first dots increasing in size, respectively, according to a distance away from said first edge along a first dimension, said first dimension being perpendicular to said first edge and said second edge;

second dots increasing in size, respectively, according to a distance away from said second edge along said first dimension;

third dots decreasing in size, respectively, according to a distance away from a third edge along a second dimension, said second dimension being parallel to said first edge and wherein said third edge is perpendicular to said first edge; and

fourth dots decreasing in size, respectively, according to a distance away from a fourth edge along said second dimension, said fourth edge being parallel to said third edge.

2. A display screen as described in claim 1 wherein said bi-directional light extraction pattern of dots comprises relatively larger sized dots disposed along said light pipe corresponding to corner areas of said light pipe.

3. A display screen as described in claim 1 wherein said bi-directional light extraction pattern of dots comprises relatively larger sized dots corresponding to an edge of said light pipe that does not have a corresponding said light source disposed along it.

4. In a flat panel display subassembly, a display screen comprising:

a thin film transparent flat panel display screen;

a pair of light sources disposed along a first edge and a second edge, respectively, of said flat panel display screen for providing light wherein said first edge is opposite said second edge;

a light pipe positioned to receive said light emitted from said pair of light sources and for uniformly distributing said light over said flat panel display screen; and

a bi-directional light extraction pattern of dots disposed on one surface of said light pipe for extracting light from said light pipe to uniformly distribute light over said flat panel display screen, wherein said light extraction pattern comprises;

first dots increasing in size, respectively, according to a distance away from said first edge along a first dimension, said first dimension being perpendicular to said first edge and said second edge;

second dots increasing in size, respectively, according to a distance away from said second edge along said first dimension; and

third dots decreasing in size, respectively, according to a distance away from a third edge along a second dimension, said second dimension being parallel to said first edge and wherein said third edge is perpendicular to said first edge.

5. A display screen as described in claim 4 wherein said bi-directional light extraction pattern of dots comprises relatively larger sized dots disposed on corner areas of said light pipe.

6. A display screen as described in claim 4 wherein said bi-directional light extraction pattern of dots comprises relatively larger sized dots corresponding to opposite edges of said light pipe that do not have corresponding light sources disposed along them.

7. A removable back-lighting assembly for providing light distribution uniformly over a flat panel display screen, said removable back-lighting assembly comprising:

a door cover for providing structural support;

a rear reflector disposed adjacent to said door cover;

a light pipe disposed adjacent to said rear reflector with a light extraction pattern disposed in between, said light extraction pattern disposed onto a surface of said light pipe;

a multi-layer structure disposed to cover said light pipe for providing uniform light diffusion and brightness enhancement;

a first "L" shaped clamp disposed along a first edge of said light pipe for securing said multi-layer structure, said light pipe, and said rear reflector to said door cover, said first "L" shaped clamp having a thin lip of approximately 1.5 mm or less, said first "L" shaped clamp being removable and secured to said first edge using two corner-located screws; and

a second "L" shaped clamp disposed along a second edge of said light pipe for securing said multi-layer structure, said light pipe, and said rear reflector to said door cover, said second "L" shaped clamp having a thin lip of approximately 1.5 mm or less, wherein said second edge is opposite to said first edge and wherein said second "L" shaped clamp is removable and secured to said second edge using two corner-located screws.

8. A removable back-lighting assembly as described in claim 7 wherein said multi-layer structure comprises:

a light gain diffuser layer disposed adjacent to said light pipe;

a brightness enhancement film layer disposed adjacent to said light gain diffuser layer; and

a protector layer disposed over said brightness enhancement film layer for protection.

9. A removable back-lighting assembly as described in claim 7 wherein said light pipe comprises a third edge, perpendicular to said first edge, for receiving back-light from a first light source and a fourth edge, opposite to said third edge, for receiving back-light from a second light source.

10. A removable back-lighting assembly as described in claim 8 wherein said light pipe comprises a third edge, perpendicular to said first edge, for receiving back-light from a first light source and a fourth edge, opposite to said third edge, for receiving back-light from a second light source.

11. A removable back-lighting assembly for providing light distribution uniformly over a flat panel display screen, said removable back-lighting assembly for insertion into said flat panel display subsystem for direct viewing, said removable back-lighting assembly comprising:

a door cover for providing structural support;

a rear reflector disposed adjacent to said -door cover;

a planar shaped light pipe disposed adjacent to said rear reflector with a light extraction pattern disposed in between, said light extraction pattern disposed onto a surface of said light pipe;

a multi-layer structure disposed to cover said light pipe for providing light diffusion and brightness enhancement;

a first "L" shaped clamp disposed along a first edge of said light pipe for securing said multi-layer structure, said light pipe, and said rear reflector to said door cover, said first "L" shaped clamp having a thin lip of approximately 2.0 mm or less, said first "L" shaped clamp being removable and secured to said first edge using two corner-located screws; and

a second "L" shaped clamp disposed along a second edge of said light pipe for securing said multi-layer structure, said light pipe, and said rear reflector to said door cover, said second "L" shaped clamp having a thin lip of approximately 2.0 mm or less, wherein said second edge is opposite to said first edge and wherein said second "L" shaped clamp is removable and secured to said second edge using two corner-located screws.

12. A removable back-lighting assembly as described in claims 11 wherein said multi-layer structure comprises:

a light gain diffuser layer disposed adjacent to said light pipe;

a brightness enhancement film layer disposed adjacent to said light gain diffuser layer; and

a protector layer disposed over said brightness enhancement film layer for protection.

13. A removable back-lighting assembly as described in claim 11 wherein said display subassembly further comprises:

a flat panel display matrix having a first surface for viewing during direct monitoring and an opposite surface for viewing during overhead projection monitoring; and

a light source positioned along two opposite edges of said flat panel display matrix for providing back-light for said flat panel display matrix.