Intrinsic polarizer and method of manufacturing an intrinsic polarizer

• US 7,573,637 B2
• Filed: 08/03/2004
• Issued: 08/11/2009
• Est. Priority Date: 08/03/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Mack, Jonathan M., Ralli, Philip J., Nkwantah, Gerald N., Nagarkar, Pradnya V., Gerlach, Michael K.
• Primary Examiner(s): Shafer; Ricky D
• Application Number:
  US10/910,211
• Publication Number:
  US 20060028725A1
• Time in Patent Office: 1,834 Days
• Field of Search: 359/490, 359/491, 359/492, 359/500
• US Class Current: 359/487.02
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid

Abstract

An improved method of forming an intrinsic polarizer, referred to as a K-type polarizer, includes stretching a polymeric film a first stretching step. The polymeric film comprises a hydroxylated linear polymer which is converted after the first stretching step to form dichroic, copolymer polyvinylene blocks aligned in the polymeric film. The polymeric film is stretched in a second stretching step while converting the hydroxylated linear polymer. This method produces an improved K-type polarizer with excellent polarizing and color characteristics. For example, the dichroic ratio is higher than 100, the color shift for light passed through the polarizer in a crossed configuration is low, and the absorption of light in the blue region of the visible spectrum is more than one half of the absorption for light in the middle of the visible spectrum.

Claims

1. An intrinsic polarizer, comprising:

a sheet of polyvinyl alcohol-type matrix including vinylene polymer blocks, the sheet defining a pass polarization axis and a block polarization axis perpendicular to the pass polarization axis, light having an electrical vector parallel to the pass polarization axis being substantially transmitted through the sheet and light having an electrical vector parallel to the block polarization axis being substantially absorbed by the vinylene polymer blocks, the sheet having an intrinsic absorption spectrum such that, when crossed with an identical sheet and illuminated with a cold cathode fluorescent tube (CCFT) light source, the sheet transmits light having an a* co-ordinate with a magnitude of less than 2 and a b* co-ordinate with a magnitude of less than 2, wherein the a* and b* co-ordinates are measured accordingly to the CIELAB color system,

a concentration of vinylene polymer blocks having a chain length n less than or equal to 9 being greater than a concentration of vinylene polymer blocks having a chain length greater than 9.

2. The polarizer according to claim 1, wherein the transmitted light has an a* value with a magnitude less than 1.

3. The polarizer according to claim 1, wherein the transmitted light has a b* value with a magnitude less than 1.

4. The polarizer according to claim 1, wherein the transmitted light has an a* value with a magnitude of less than 1 and a b* value with a magnitude less than 1.

5. The polarizer according to claim 1, wherein the sheet exhibits a ratio, R, having a value of less than 2, where R is a ratio of absorbance for light at 550 nm polarized parallel to the block polarization axis over absorbance for light at 400 nm polarized parallel to the block polarization axis.

6. The polarizer according to claim 5, wherein R has a value of less than 1.7.

7. The polarizer according to claim 1, wherein the sheet exhibits a polarization efficiency in excess of 99%.

8. The polarizer according to claim 7, wherein the polarization efficiency ratio is greater than 99.5%.

9. The polarizer according to claim 7, wherein the polarization efficiency ratio is greater than 99.8%.

10. The polarizer according to claim 1, wherein the average light transmission for unpolarized light, Kv, through the sheet is greater than 42%.

11. The polarizer according to claim 10, wherein Kv has a value greater than 43%.

12. The polarizer according to claim 1, wherein the sheet exhibits a polarization dichroic ratio of more than 100.

13. The polarizer according to 12, wherein the sheet exhibits a dichroic ratio of more than 110.