Optical device having reverse mode holographic PDLC and front light guide

• US 6,618,104 B1
• Filed: 07/27/1999
• Issued: 09/09/2003
• Est. Priority Date: 07/28/1998
• Status: Expired due to Fees

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Kato, Kinya, Uehira, Kazutake, Suyama, Shiro, Date, Munekazu
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): SCHECHTER, ANDREW M
• Application Number:
  US09/361,856
• Time in Patent Office: 1,505 Days
• Field of Search: 349/63, 349/201, 349/86, 349/88, 349/92, 349/94
• US Class Current: 349/86
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02F 1/13336 Combining plural substrates to produce large-area displays, e.g. tiled displays
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13342 Holographic polymer dispersed liquid crystals
• CPC Class Codes: G02F 1/13347 working in reverse mode, i.e. clear in the off-state and scattering in the on-state
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/13712 the liquid crystal having negative dielectric anisotropy
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2201/08 light absorbing layer
• CPC Class Codes: G02F 2201/124 interdigital
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2203/023 total internal reflection
• CPC Class Codes: G02F 2203/026 attenuated or frustrated internal reflection

Abstract

An optical device and a display apparatus of the present invention are constructed so as to improve display characteristics of output light intensity, display contrast, and reduction of scattered light due to external light, and also to provide a large-screen. The optical device has a first stacked body and a plurality of second stacked bodies. The first stacked body includes a light guide, a fist electrode, and an optical control layer. The second stacked body includes a plurality of second electrodes, the reflection film and a substrate. A plurality of third electrodes are provided through the substrate. Each of the third electrode has a first end part connecting to the second electrode and a second end part exposed to the other side of the substrate. A further light absorption film may be disposed between the reflection film and the second electrode.

Claims

1. An optical device comprising a light transmissive plate-shaped light guide for guiding light incident from an end surface, an optical control layer provided on a lower surface of said plate-shaped light guide through a transparent electrode provided as a first electrode, and a reflection plate made of a light transmissive plate provided on a lower surface of said optional control layer through a transparent electrode provided as a second electrode,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of a diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in diffraction ability by an electric field applied by said first electrode and said second electrode so that said optical control layer becomes a birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

2. The optical device as claimed in claim 1, wherein at least one of said first electrode and second electrode comprises an electrode group divided into strips, when both of said first electrode and second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

3. The optical device as claimed in claim 1, wherein one of said first electrode and second electrode is divided into display pixel units and each of said divided display pixel units has a switching device.

4. An optical device comprising a light transmissive plate-shaped light guide for guiding light incident from an end surface, an optical control layer provided on a lower surface of said plate-shaped light guide through a transparent electrode provided as a first electrode, and a second electrode which is an electrode provided on a lower surface of said optical control layer for making mirror reflection of light,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of a diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in diffraction ability by an electric field applied by said first electrode and said second electrode so that said optical control layer becomes a uniform birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

5. The optical device as claimed in claim 4, wherein at least one of said first electrode and second electrode comprises an electrode group divided into strips, when both of said first electrode and second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

6. The optical device as claimed in claim 4, wherein one of said first electrode and second electrode is divided into display pixel units and each of said divided display pixel units has a switching device.

7. A display apparatus comprising an optical device and a illumination means for applying light to said optical device,

wherein said optical device has an end surface for incident light from said illumination means, a light transmissive plate-shaped light guide for guiding incident light, an optical control layer provided on a lower surface of said plate-shaped light guide through a transparent electrode provided as a first electrode, and a reflection plate made of a light transmissive plate provided on a lower surface of said optical control layer through a transparent electrode provided as a second electrode,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of a diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in diffraction ability by an electric field applied by said first electrode and said second electrode so that said optical control layer becomes a uniform birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

8. The display apparatus as claimed in claim 7, wherein at least one of said first electrode and second electrode comprises an electrode group divided into strips, when both of said first electrode and second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

9. The display apparatus as claimed in claim 7, wherein at least one of said first electrode and second electrode is divided into display pixel units, and each of said divided display pixel units has a switching device.

10. The display apparatus as claimed in claim 7, wherein said illumination means has at least a red light source, a blue light source, and a green light source, and further comprising means for successively switching said red light source, blue light source and green light source in synchronization with display image.

11. A display apparatus comprising an optical device and a illumination means for applying light to said optical device,

said optical device has an end surface for incident light from said illumination means, a light transmissive plate-shaped light guide for guiding incident light, an optical control layer provided on a lower surface of said plate-shaped light guide through a transparent electrode provided as a first electrode, and a second electrode provided as an electrode on a lower surface of said optical control layer for making mirror reflection of light,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of a diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in diffraction ability by an electric field applied by said first electrode and said second electrode so that said optical control layer becomes a uniform birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

12. The display apparatus as claimed in claim 11, wherein at least one of said first electrode and second electrode comprises an electrode group divided into strips, when both of said first electrode and second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

13. The display apparatus as claimed in claim 11, wherein at least one of said first electrode and second electrode is divided into display pixel units, and each of said divided display pixel units has a switching device.

14. The display apparatus as claimed in claim 11, wherein said illumination means has at least a red light source, a blue light source, and a green light source, and further comprising means for successively switching said red light source, blue light source and green light source in synchronization with display image.

15. An optical device comprising a light transmissive plate-shaped light guide for guiding light incident from an end surface, an optical control layer provided on a lower surface of said light guide through a transparent electrode provided as a first electrode, and a reflection film provided on a lower surface of said optical control layer through a transparent electrode provided as a second electrode,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of a diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in scattering degree or diffraction efficiency field applied by said first electrode and said second electrode so that said optical control layer becomes a uniform birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

16. The optical device as claimed in claim 15, further comprising a light absorption film provided on a lower surface of said reflection film.

17. The optical device as claimed in claim 15 or 16, wherein at least one of said first electrode and said second electrode comprises an electrode group divided into strips, when both of said first electrode and said second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

18. The optical device as claimed in claim 15 or 16, wherein at least one of said first electrode and said second electrode is divided into display pixel units, and each of said divided display pixel units has a switching device.

19. The optical device as claimed in claim 15 or 16, wherein said optical control layer is made of a reverse mode polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and said optical control layer becomes a uniform birefringent thin film when no electric field is applied and becomes a scattering state when an electric field is applied.

20. The optical device as claimed in claim 15 or 16, wherein said optical control layer comprises one of constructions of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which respective polymer resin area and liquid crystal area form continuous areas.

21. The optical device as claimed in claim 15 or 16, wherein said optical control layer comprises a holographic polymer dispersed liquid crystal of liquid crystal area having a structure periodically distributed in the form of a diffraction grating.

22. The optical device as claimed in claim 15 or 16, wherein said reflection film comprises one selected from:

a dielectric multilayered film; and

a film lower in refractive index than said light guide.

23. A display apparatus comprising an optical device and a illumination means for applying light to said optical device,

said optical device having an end surface for incident light from said illumination means, a light transmissive plate-shaped light guide for guiding incident light, an optical control layer provided on a lower surface of said plate-shaped light guide through a transparent electrode provided as a first electrode, a reflection film provided on a lower surface of said optical control layer through a transparent electrode provided as a second electrode, and a substrate provided on a lower surface of said reflection film,

wherein said optical control layer is selected from the group consisting of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which a respective polymer resin area and a liquid crystal area are continuous,

wherein said liquid crystal has a structure periodically distributed in the form of diffraction grating, and

wherein said optical control layer is made of a reverse mode holographic polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and changes in scattering degree or diffraction efficiency by an electric field applied by said first electrode and said second electrode so that said optical control layer becomes a uniform birefringent thin film in the absence of any applied electric field, while said optical control layer becomes said diffraction grating for functioning as a hologram when an electric field is applied.

24. The display apparatus as claimed in claim 23, further comprising a light absorption film provided on a lower surface of said reflection film.

25. The display apparatus as claimed in claim 23 or 24, wherein at least one of said first electrode and said second electrode comprises an electrode group divided into strips, when both of said first electrode and said second electrode comprise electrode groups divided into strips, said plurality of strip-formed electrodes constituting said first electrode and said plurality of strip-formed electrodes constituting said second electrodes are disposed to be perpendicular to each other.

26. The display apparatus as claimed in claim 23 or 24, wherein at least one of said first electrode and said second electrode is divided into display pixel units, and each of said divided display pixel units has a switching device.

27. The display apparatus as claimed in claim 23 or 24, wherein said optical control layer is made of a reverse mode polymer dispersed liquid crystal which is constructed by dispersing a low molecular-weight liquid crystal in a liquid crystalline polymer, and said optical control layer becomes a uniform birefringent thin film when no electric field is applied and becomes a scattering state when an electric field is applied.

28. The display apparatus as claimed in claim 23 or 24, wherein said optical control layer comprises one of constructions of liquid crystal particles dispersed in a polymer resin area, a polymer dispersed liquid crystal comprising polymer resin particles dispersed in a liquid crystal, and a polymer dispersed liquid crystal in which respective polymer resin area and liquid crystal area form continuous areas.

29. The display apparatus as claimed in claim 23 or 24, wherein said optical control layer comprises a holographic polymer dispersed liquid crystal of liquid crystal area having a structure periodically distributed in the form of a diffraction grating.

30. The display apparatus as claimed in claim 23 or 24, wherein said reflection film comprises one selected from a dielectric multilayered film, and a film lower in refractive index than said light guide.

31. The display apparatus as claimed in claim 23 or 24, wherein said illumination means has at least a red light source, a blue light source, and a green light source, and further comprising means for successively switching said red light source, blue light source and green light source in synchronization with display image.