METHOD AND APPARATUS FOR FABRICATING A LIGHT MANAGEMENT SUBSTRATES

• US 20050199501A1
• Filed: 04/29/2005
• Published: 09/15/2005
• Est. Priority Date: 12/18/2002
• Status: Active Grant

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Olczak, Eugene, Liang, Erwin W.
• Granted Patent: US 7,452,490 B2
• Time in Patent Office: Days
• US Class Current: 205/79
• CPC Class Codes: G05B 19/182 characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control G05B19/21 - G05B19/40 take precedence
• CPC Class Codes: G05B 2219/35261 Use of mathematical expression, functional equation

Abstract

A method of machining a surface of a workpiece is accomplished by bringing a cutting tool into contact with the surface of the workpiece and for at least one cutting pass, i, causing relative movement between the cutting tool and the surface of the workpiece along a path in the surface of the workpiece. The path is in the nature of a mathematical function defined over a segment, C, of a coordinate system and characterized by a set of nonrandom, random or pseudorandom parameters selected from the group consisting of amplitude, phase and period or frequency. Relative movement between the cutting tool and the surface of the workpiece may be accomplished by bandpass filtering a noise signal; providing the bandpass filtered signal to a function generator; generating a randomly modulated mathematical function from the function generator; and in response to the randomly modulated function, directing the relative movement between the cutting tool and the surface of the workpiece along the path in the surface of the workpiece.

Claims

1. A method of fabricating an optical substrate from a machined surface of a workpiece, the method comprising:

forming a positive or negative electroform over the surface of the surface of the workpiece;

forming a replica of the electroform; and

transferring the replica of the electroform to an optical substrate.

2. An optical substrate comprising:

a surface formed from a master surface machined by bringing a cutting tool into contact with a surface of a workpiece;

for at least one cutting pass, i, causing relative movement between the cutting tool and the surface of the workpiece along a path in the surface of the workpiece;

wherein the path is in the nature of a mathematical function defined over a segment, C, of a coordinate system and characterized by a set of nonrandom, random or pseudorandom parameters selected from the group consisting of amplitude, phase and frequency;

forming a positive or negative electroform over the surface of the surface of the workpiece;

forming a replica of the electroform; and

transferring the replica of the electroform to an optical substrate.

3. A backlight display device comprising:

an optical source for generating light;

a light guide for guiding the light therealong;

a reflective device positioned along the light guide for reflecting the light out of the light guide;

an optical substrate receptive of the light from the light guide, the optical substrate comprising;

a surface formed from a master surface machined by bringing a cutting tool into contact with a surface of a workpiece;

for at least one cutting pass, i, causing relative movement between the cutting tool and the surface of the workpiece along a path in the surface of the workpiece;

wherein the path is in the nature of a mathematical function defined over a segment, C, of a coordinate system and characterized by a set of nonrandom, random or pseudorandom parameters selected from the group consisting of amplitude, phase and frequency;

forming a positive or negative electroform over the surface of the surface of the workpiece;

forming a replica of the electroform; and

transferring the replica of the electroform to an optical substrate.

4. A backlight display device comprising:

an optical source for generating light;

a light guide for guiding the light therealong; and

a reflective device positioned along the light guide for reflecting the light out of the light guide;

wherein the light guide includes a surface formed from a master surface machined by

bringing a cutting tool into contact with a surface of a workpiece;

for at least one cutting pass, i, causing relative movement between the cutting tool and the surface of the workpiece along a path in the surface of the workpiece;

wherein the path is in the nature of a mathematical function defined over a segment, C, of a coordinate system and characterized by a set of nonrandom, random or pseudorandom parameters selected from the group consisting of amplitude, phase and frequency;

forming a positive or negative electroform over the surface of the surface of the workpiece;

forming a replica of the electroform; and

transferring the replica of the electroform to an optical substrate.

5. The display device as set forth in claim 4 wherein for a kth cutting pass, subsequent to the ith cutting pass, a width wk of the kth cutting pass is different than the ith cutting pass.

6. The display as set forth in claim 5 wherein for a kth cutting pass, subsequent to the ith cutting pass, the difference in the width wk of the kth cutting pass with respect to the ith cutting pass is a gradient over all cutting passes.

7. The display as set forth in claim 5 wherein for a kth cutting pass, subsequent to the ith cutting pass, the difference in the width wk of the kth cutting pass with respect to the ith cutting pass is random or pseudo random.