Liquid crystal display unit

• US 6,102,545 A
• Filed: 04/17/1997
• Issued: 08/15/2000
• Est. Priority Date: 10/18/1994
• Status: Expired due to Term

• Current Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ogino, Masanori
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US08/836,142
• Time in Patent Office: 1,216 Days
• Field of Search: 353/20, 353/38, 353/98, 353/99, 353/57, 362/296, 362/297, 362/298, 362/346, 362/347, 349/61, 349/67
• US Class Current: 353/38
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133623 Inclined coloured light beams
• CPC Class Codes: G02F 1/133627 Projection-direct viewing
• CPC Class Codes: G02F 1/133628 with cooling means
• CPC Class Codes: G03B 21/006 using LCD's
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A liquid crystal display unit wherein a first light-refracting means, a second light-refracting means, a first light-reflecting means and a third light-refracting means are disposed in a light path of from a light source means to a liquid crystal panel means, and wherein light-converging power (reciprocal of focal length) of the third light-refracting means is selected to be algebraically small in its outer circumferential portion and large in its inner circumferential portion, so that it is possible to improve the efficiency of use of light of the liquid crystal display unit, the relative corner illuminance, the contrast ratio and the image quality.

Claims

1. In a projection type display unit having a black stripe screen, a projection lens, and a liquid crystal panel means,

a liquid crystal display unit with reduced moire interference comprising at least a light-diverging means disposed in a light path from said liquid crystal panel means to said projection lens for diverging light horizontally and constituted so that a half-value width of a horizontal spread of spot size by said light-diverging means is not smaller than a value 0.75 times as large as a period of arrangement of black stripes, and a frequency response of said light diverging means is not smaller than 0.3 at the largest data frequency which can be restored by said liquid crystal panel means.

2. A liquid crystal display unit according to claim 1, wherein said display unit is a rear projection type liquid crystal display unit and comprises optical disc storing shelves provided in at least one of left and right portions below said screen means.

3. A projection type liquid crystal display unit according claim 1, further comprising half-wavelength phase plate means disposed between said liquid crystal panel means and said screen means so that in-put light to said screen means is transformed into a vertical polarized wave.

14. A projection type liquid crystal display unit according to claim 1, further comprising quarter-wavelength phase plate means which is formed integrally with light-deflecting means formed on an output face of said liquid crystal panel means.

15. A projection type liquid crystal display unit according to any one of claims 1, 4, or 9, wherein field lens means is provided at an output side of said liquid crystal panel means so that the direction of output light rays is deflected toward a pupil of said projection lens by said field lens means.

16. A projection type liquid crystal display unit according to claim 15, wherein said field lens means is constituted by two Fresnel sheets which are joined with each other in a manner so that respective lens faces of said two Fresnel sheets are made to face each other with their prism phases made coincident with each other.

4. A projection type liquid crystal display unit having a transparent flexible plate means disposed between a liquid crystal panel means and a projection lens means so that geometric distortion on a reproduced image is compensated by bending and adjusting respective peripheral portions of said transparent flexible plate means.

5. A liquid crystal display unit comprising a light source means for emitting white light rays, a liquid crystal panel means, and a light-ray direction transforming means for guiding output light of said light source means to said liquid crystal panel means, wherein

a three-direction means for separating light of three primary colors into light rays of three different directions, a three-position means for converging said light rays of three different directions toward three different positions, and a light-divergence-reducing means for reducing an angle of divergence of light are disposed along a traveling direction of light in an input side of said liquid crystal panel means, a thickness T₁ of a medium between said three-position means and said light-divergence-reducing means being formed so as to be not smaller than 0.6 times but not larger than 1.2 times as large as a focal length of said light-divergence-reducing means, a focal length f of said three-position means being formed so as to be not smaller than T₁ but not larger than 1.6T₁, whereby direction differences of said light rays of said three primary colors are reduced and said light rays of said three primary colors are guided to respective pixel positions for said three primary colors.

6. A liquid crystal display unit according to claim 5, further comprising polarization-direction matching means disposed between said liquid crystal panel means and said three-direction means for making a light-separating direction of said three-direction means substantially coincident with a wide-directivity direction of said liquid crystal panel means.

7. A liquid crystal display unit according to claim 5, wherein said three-position means and said light-divergence-reducing means are constituted by an input-side lenticular lens and an output-side lenticular lens, respectively, in one sheet of double-sided lenticular lens means disposed on a light-input side of said liquid crystal panel means.

8. A liquid crystal display unit according to claim 7, wherein a lenticular lens means is further disposed on a light-input side of said double-sided lenticular lens means so that a light-converging direction of said lenticular lens means is substantially perpendicular to a light-converging direction of said double-sided lenticular lens means.

9. A liquid crystal display unit according to claim 5, wherein said display unit is a projection type liquid crystal display unit and further comprises a projection lens means and a screen means.

10. A liquid crystal display unit according to claim 5, wherein light-utilizing efficiency improving means constituted by a polarizing beam splitter, a half wavelength plate for rotating a plane of polarization by 90 degrees and a reflecting mirror are disposed between said light-ray-direction transforming means and said three direction means.

11. A liquid crystal display unit according to claim 5 wherein said display unit is an optical fiber type liquid crystal display unit and wherein light-receiving ends of optical fiber means are disposed on an output side of said liquid crystal panel means.

12. A liquid crystal display unit according to claim 5 wherein said display unit is a direct view type liquid crystal display unit and further comprises a lenticular lens means disposed on an output side of said liquid crystal panel means so that a light diverging direction of said lenticular lens means is made substantially coincident with a narrow-directivity direction of said liquid crystal panel means.

13. A liquid crystal display unit according to claim 8, wherein stripe type-polarization direction rotating means are disposed on a light-output side of said liquid crystal panel means so that a plane of polarization of an output light of said lenticular lens means is rotated by 90 degrees line-by-line every two lines by said polarization direction rotating means.

20. A liquid crystal display unit according to claim 10, further comprising quarter-wavelength phase plate means which is disposed between said light ray-direction transforming means and said polarizing beam splitter with its light-anomaly axis inclined by 45°

relative to a horizontal direction.

17. In a projection type display unit having a black stripe screen, a projection lens, and a liquid crystal panel,

a liquid crystal display unit with reduced moire interference comprising at least a light-diverging unit disposed in a light path from said liquid crystal panel to said projection lens diverging light horizontally and constituted so that a half-value width of a horizontal spread of spot size by said light-diverging unit is not smaller than a value 0.75 times as large as a period of arrangement of black stripes, and the frequency response of said light diverging means is not smaller than 0.3 at the largest data frequency which can be restored by said liquid crystal panel.

18. A projection type liquid crystal display unit having a transparent flexible plate disposed between a liquid crystal panel and a projection lens so that geometric distortion on a reproduced image is compensated by bending and adjusting respective peripheral portions of said transparent flexible plate.

19. A liquid crystal display unit comprising a light source emitting white light rays, a liquid crystal panel, and a light-ray direction transforming unit guiding output light of said light source to said liquid crystal panel, wherein

a three-direction separator separating light of three primary colors into light rays of three different directions, a three-position converger converging said light rays of three different directions toward three different positions, and a light-divergence reducer reducing an angle of divergence of light are disposed along a traveling direction of light in an input side of said liquid crystal panel means, a thickness T₁ of a medium between said three-position converger and said light-divergence reducer being formed so as to be not smaller than 0.6 times but not larger than 1.2 times as large as a focal length of said light-divergence reducer, a focal length f of said three-position converger being formed so as to be not smaller than T₁ but not larger than 1.6T₁, whereby direction differences of said light rays of said three primary colors are reduced and said light rays of said three primary colors are guided to respective pixel positions for said three primary colors.