EP0731603A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Video projection type display device
Assignee: Seiko Epson Corp
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Filing: 1996-03-07
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Granted: —
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Expires: 2016-03-07
Abstract
Abstract A projection-type display device comprises a light source (1) for emitting a light beam including the three primary colors, a color separation system (10) for separating the light beam three color light beams, light modulation units (3R, 3G, 3B) each having a liquid crystal panel with a polarizing plate on the output surface thereof for modulating each of the three color light beams in accordance with a video signal, a first phase plate (7R, 7G, 7B) provided on the output side of the polarizing plate for converting a linearly polarized light beam into a circularly polarized light beam, a second phase plate (8R, 8G, 8B) provided on the output side of the first phase plate for converting the circularly polarized light beam into a linearly polarized light beam, a light combining system (11) for combining the light beams that have passed through the second phase plate (11), and an optical projection system (2) for projecting the combined light beams on a screen (9) in enlarged fashion. The purpose of the invention is to prevent a reflected light beam caused by a optical projection system or a light combining system to be incident on a liquid crystal panel, as well as to convert a light beam to be projected on the screen or light beams incident on the light combining system into a linearly polarized light, to obtain a projection-type display device which has good display characteristics.
Inventors
- 👤 Syuji Aruga
- 👤 Hirosada Horiguchi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:30
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/74; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; H04N9/3105; H04N5/7416; H04N5/7441; H04N9/3141; H04N9/315; H04N9/3167
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
209 words
A projection-type display device comprising: light source means (1), at least one light processing unit (3, 7, 8; 3R, 3B, 3G, 7R, 7B, 7G, 8R, 8B, 8G; 31, 71, 81; 32, 72, 82) including a light modulation unit (3; 3R, 3B, 3G; 31; 32) having a liquid crystal panel (5; 5R, 5B, 5G; 51; 52) and a polarizing plate (6; 6R, 6B, 6G; 61; 62) arranged on a light output surface of the liquid crystal panel for modulating light emitted from the light source means in accordance with a video signal, and a first phase plate (7; 7R, 7B, 7G; 71; 72) provided on the output side of said polarizing plate and adapted to convert a linearly polarized light beam that has passed through the light modulation unit into a circularly polarized light beam, and projection means (2) for projecting the modulated light onto a screen (9) in an enlarged fashion, wherein said at least one light processing unit further includes a second phase plate (8; 8R, 8B, 8G; 81; 82) provided on the output side of the first phase plate for converting the circularly polarized light beam that has passed through the first phase plate into a linearly polarized light beam to be projected by said projection means.
Claim 2
Dependent Claim
54 words
The device according to claim 1, wherein both the first and the second phase plates (7, 8; 7R, 7B, 7G, 8R, 8B, 8G; 71, 81; 72, 82) are a λ/4 plate and the slow axis of the first phase plate is 45° offset with respect to the light transmission axis of said polarizing plate.
Claim 3
Dependent Claim
41 words
The device according to claim 2, wherein the slow axis of the second phase plate (8; 8R, 8B, 8G; 81; 82) is 90° offset with respect to the slow axis of the first phase plate (7; 7R, 7B, 7G; 71; 72).
Claim 4
Independent Claim
58 words
The device according to any one of claims 1, 2 or 3, wherein the light modulation unit (3; 3R, 3B, 3G; 31; 32), the first phase plate (7; 7R, 7B, 7G; 71; 72), and the second phase plate (8; 8R, 8B, 8G; 81; 82) are arranged so that the light beam projected on the screen (9) is S-polarized.
Claim 5
Independent Claim
116 words
The device according to any one of the preceding claims further comprising: light source means (1) capable of emitting light including the three primary colors, color separation means (10) for separating the light emitted from the light source into three color light beams, three of said light modulation units (3R, 3B, 3G), means (10, 171-173) for directing each of the three color light beams through a respective one of said light modulation units, and combining means (11) for recombining the modulated color light beams for projection by said projection means, wherein said first and second phase plates are provided on the output side of the polarizing plate of at least one of said light modulation units.
Claim 6
Dependent Claim
35 words
The device according to claim 5, wherein said three light processing units (3R, 3B, 3G) are arranged so that the color light beams incident on said combining means (11) have the same direction of polarization.
Claim 7
Dependent Claim
16 words
The device according to claim 6, wherein the direction of polarization is that of S-polarized light.
Claim 8
Dependent Claim
39 words
The display device according to claim 5, wherein wherein respective first and second phase plates (7R, 7B, 7G, 8R, 8B, 8G) are provided on the output side of the polarizing plate of each of said three light modulation units.
Claim 9
Dependent Claim
36 words
The device according to claim 5, wherein said first and second phase plates are provided on the output side of the polarizing plate of only the light modulation unit (3B) for modulating a blue light beam.
Claim 10
Dependent Claim
44 words
The device according to claim 8, wherein both the first and the second phase plates (7R, 7B, 7G, 8R, 8B, 8G) are optimized with respect to the respective color of the color light beam incident on the corresponding light modulation unit (3R, 3B, 3G).
Claim 11
Dependent Claim
25 words
The device according to claim 10 or 11, wherein both the first and the second phase plates are optimized with respect to the blue color.
Claim 12
Independent Claim
22 words
The device according to any one of claims of 5 through 11, wherein said combining means (11) comprises a prism combining system.
Claim 13
Independent Claim
105 words
The device according to any one of claims 1 to 4, further comprising: light separation means (161) for separating white light emitted from said light source (1) into a P-polarized light component and an S-polarized light component, first and second light processing units (31, 71, 81, 32, 72, 82), means (174, 176) for directing one of the two components to the first and the other to the second light processing unit for modulating the two components by different video signals, such as a chrominance signal and a luminance signal, and combining means (162) for recombining the modulated components for projection by said projection means (2).
Claim 14
Independent Claim
123 words
The device according to any one of claims 5 to 12, further comprising: light separation means (161) for separating white light emitted from said light source (1) into a P-polarized light component and an S-polarized light component, said light separation means being interposed between said light source means and said color separation means (10), means (161) for directing one of the two components to said color separation means (10), means (161, 174; 161') for directing the other component to an additional one (31, 71, 81) of said light processing units for modulating said other component by a luminance signal, and additional combining means (162) for combining the recombined color light beams and the modulated other component for projection by said projection means (2).
References Cited (Backward Citations)
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