Reflection-type liquid crystal device with polarization of output light perpendicular to that of input light
A reflection-type liquid crystal (LC) device having a twisted nematic (TN) LC layer that lets linearly-polarized incident light enter and become circularly-polarized at a reflecting surface, and then linearly polarizes it, after reflecting, with a plane of polarization that has been rotated 90.degree. from the incident light at an light output surface. The TN LC layer allows linearly-polarized incident light to enter at an angle to the molecular plane of light input of the twisted nematic LC, and to linearly polarize the light after reflection. The plane of polarization is rotated 90.degree. from the incident light at the light output surface. The TN LC layer also allows circularly-polarized incident light to enter and become linearly-polarized light at the reflecting surface. Circularly-polarized light after reflection may be rotated opposite the incident circularly-polarized light at the light output surface to provide for reverse on/off states.
Latest Seiko Epson Corporation Patents:
- LIQUID EJECTING APPARATUS AND LIQUID EJECTING SYSTEM
- LIQUID EJECTING SYSTEM, LIQUID COLLECTION CONTAINER, AND LIQUID COLLECTION METHOD
- Piezoelectric element, piezoelectric element application device
- Medium-discharging device and image reading apparatus
- Function extension apparatus, information processing system, and control method for function extension apparatus
Claims
2. The reflection-type liquid crystal device of claim 1 wherein light passing through said polarizing means prior to entering said liquid crystal layer is substantially first linearly polarized light and is converted by birefringence property of said liquid crystal layer to substantially circularly polarized light at said reflecting means, and said substantially circularly polarized light is reflected and is converted by birefringence property of said liquid crystal layer to substantially second linearly polarized light upon passing again through said liquid crystal layer, said first and second linearly polarized light having respective axes of polarization that are substantially orthogonal with one another.
3. The reflection-type liquid crystal device of claim 2 wherein said conversions transpire during an OFF state of said device.
4. The reflection-type liquid crystal device of claim 1 wherein light passing through said polarizing means prior to entering said liquid crystal layer is substantially first circularly polarized light and is converted by birefringence property of said liquid crystal layer to substantially linearly polarized light at said reflecting means, and said substantially linearly polarized light is reflected and converted by birefringence property of said liquid crystal layer to substantially second circularly polarized light upon passing again through said liquid crystal layer, said first and second circularly polarized light having opposite directions of rotation.
5. The reflection-type liquid crystal device of claim 4 wherein said conversions transpire during an OFF state of said device.
6. The reflection-type liquid crystal device of claim 4 further comprising a quarter wavelength plate having an optical axis in the plane of said plate and disposed between said polarizing means and said liquid crystal cell, said phase plate and polarizing means for producing said entering circularly polarized light, said liquid crystal molecular director substantially perpendicular to the optical axis of said phase plate.
7. The reflection-type liquid crystal device of claim 6 wherein said phase plate has an optical axis shifted by 45.degree. with respect to an axis of light transmission of said polarizing means.
8. The reflection-type liquid crystal device of claim 6 wherein said phase plate is a quarter wavelength plate.
9. The reflection-type liquid crystal device of claim 1 further comprising:
- an optically anisotropic element disposed between said liquid crystal cell and said polarizing means, said optically anisotropic element having an optical axis in the plane of said element,
- said liquid crystal molecular director of said liquid crystal layer and the optical axis of said optically anisotropic element arranged relative to one another to provide substantially white light during an OFF state of operation of said device.
10. The reflection-type liquid crystal device of claim 9 wherein an axis of said liquid crystal molecular director at said surface of said liquid crystal layer and the optical axis of said optically anisotropic element are substantially perpendicular.
11. The reflection-type liquid crystal device of claim 9 wherein second polarizing means and a second optically anisotropic element are disposed between said reflecting means and said liquid crystal cell, said reflecting means comprising a partially transparent reflector.
12. The reflection-type liquid crystal device of claim 9 wherein a second optically anisotropic element is disposed between said liquid crystal layer and said reflecting means.
13. The reflection-type liquid crystal device of claim 9 wherein said optically anisotropic element comprises a polycarbonate resin film, polypropylene resin film or a quarter wavelength plate.
14. The reflection-type liquid crystal device of claim 9 wherein said reflecting means has a roughened surface to provide light scattering.
15. The reflection-type liquid crystal device of claim 14 wherein said reflecting means is disposed on an inner surface of said substrate at said liquid crystal cell at said second side.
| 3960438 | June 1, 1976 | Bonne et al. |
| 3972587 | August 3, 1976 | Scheffer |
| 4019807 | April 26, 1977 | Boswell et al. |
| 4232948 | November 11, 1980 | Shanks |
| 4844569 | July 4, 1989 | Wada et al. |
| 4889412 | December 26, 1989 | Clerc et al. |
| 5105289 | April 14, 1992 | Sonehara et al. |
| 5212819 | May 18, 1993 | Wada |
| 0 352 724 | January 1990 | EPX |
| 0 377 757 | July 1990 | EPX |
| 2177352 | November 1973 | FRX |
| 2 238 200 | February 1975 | FRX |
| 56-43781 | April 1981 | JPX |
| 56-43681 | April 1981 | JPX |
| 1-88828 | July 1989 | JPX |
| 1 469 638 | April 1977 | GBX |
| WO 91/06889 | May 1991 | WOX |
- Minoru Hosokawa et al., "Active Panel Having Wide View Angle Employing Guest Host Type Liquid Crystal", Nikkei Electronics, Feb. 16, 1981, pp. 164-184. G. Paul Montgomery, Jr., "Optical properties of a liquid-crystal image transducer at normal incidence: Mathematical analysis and application to the off-state," J. Opt. Soc. Am., vol. 70, No. 3, Mar.1980, pp. 287-300. Tomio Sonehara et al., "A New Twisted Nematic ECB (TN-ECB) Mode for a Reflective Light Value", JAPAN DISPLAY'89, Oct. 16, 1989, pp. 192-195.
Type: Grant
Filed: Oct 15, 1996
Date of Patent: May 19, 1998
Assignee: Seiko Epson Corporation (Tokyo)
Inventors: Tomio Sonehara (Suwa), Osamu Okumura (Suwa)
Primary Examiner: Anita Pellman Gross
Attorney: Mark P. Watson
Application Number: 8/729,929
International Classification: G02F 11335; G02F 113;
