US5392142A
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US
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Display apparatus with chiral smectic and polymer liquid crystal films, each having birefringent first state and not birefringent second state
Assignee: Canon Inc
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Filing: 1994-06-27
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Granted: 1995-02-21
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Expires: 2014-06-27
Abstract
Abstract An optical modulation device is constituted by a polarizer; a first film forming a first state and a second state depending on an electric field applied thereto, the first state causing birefringence and the second state not causing birefringence respectively of polarized light from the polarizer, the first film having a thickness set for functioning as a halfwave plate in its first state; and a second film not causing birefringence of light having passed through the second state of the first film but causing birefringence of light having passed through the first state of the first film, the second film having a thickness set for functioning as quarter wave plate or a halfwave plate when the first film is set in its first state. The light from the second film is caused to enter the second film again through a reflection means or a third film selectively forming a first state causing birefringence of light which has caused birefringence and passed through the second film or a second state not causing birefringence of light which has passed through the second film without causing birefringence. The light thus modulated is then caused to enter an analyzer. As a result, an optical modulation giving a large contrast is provided by using a material having a small birefringence effect for the first film or third film.
Inventors
- 👤 Hideaki Mitsutake
- 👤 Kazuo Yoshinaga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:26
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/133528; G02F1/1347; G02F1/13471; G02F1/137; G02F1/139; G02F1/141; G02F1/13363; G02F1/133638; G02F2203/00; G02F2203/01; G02F2203/02
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
145 words
An optical modulation device, comprising: a polarizer; a first film forming a first state and a second state depending on an electric field applied thereto, the first state causing birefringence and the second state not causing birefringence respectively of polarized light from the polarizer, the first film having a thickness set for functioning as a halfwave plate in its first state; a second film of a polymer not causing birefringence of light having passed through the second state of the first film but causing birefringence of light having passed through the first state of the first film, the second film having a thickness set for functioning as a quarter wave plate that is not driver when the first film is set in its first state; a reflecting means for reflecting light having passed through the second film again to the second film; and an analyzer.
Claim 2
Dependent Claim
145 words
An optical modulation device, comprising: a polarizer; a first film forming a first state and a second state depending on an electric field applied thereto, the first state causing birefringence and the second state not causing birefringence respectively of polarized light from the polarizer, the first film having a thickness set for functioning as a halfwave plate in its first state; a second film of a polymer not causing birefringence of light having passed through the second state of the first film but causing birefringence of light having passed through the first state of the first film, the second film having a thickness set for functioning as a quarter wave plate that is not driver when the first film is set in its first state; a reflecting means for reflecting light having passed through the second film again to the second film; and an analyzer.
Claim 3
Dependent Claim
14 words
A device according to claim 1, wherein said first film comprises a liquid crystal.
Claim 4
Dependent Claim
18 words
A device according to claim 2, wherein said liquid crystal is a chiral smectic liquid crystal having bistability.
Claim 5
Dependent Claim
15 words
A device according to claim 1, wherein said second film comprises a polymer liquid crystal.
Claim 6
Dependent Claim
23 words
A device according to claim 1, which further comprises voltage application means including a pair of electrodes disposed to sandwich the first film.
Claim 7
Dependent Claim
45 words
A device according to claim 1, which further comprises voltage application means including a pair of electrodes disposed to sandwich the first film, and means for applying a pulse of one polarity and a pulse of the other polarity selectively between the pair of electrodes.
Claim 8
Dependent Claim
16 words
A device according to claim 1, wherein said first film has a thickness of 1.2-1.6 microns.
Claim 9
Dependent Claim
16 words
A device according to claim 1, wherein said second film has a thickness of 0.6-0.8 micron.
Claim 10
Dependent Claim
39 words
A device according to claim 1, which further comprises a voltage application means including a pair of electrodes sandwiching the first film with one of said pair of electrodes being disposed between the first film and the second film.
Claim 11
Dependent Claim
26 words
A device according to claim 9, wherein said first film comprises a bistable chiral smectic liquid crystal and said second film comprises a polymer liquid crystal.
Claim 12
Dependent Claim
31 words
A device according to claim 9, which further comprises a means for applying a pulse of one polarity and a pulse of the other polarity selectively between the pair of electrodes.
Claim 13
Dependent Claim
171 words
A display apparatus, comprising: a light source for emitting indefinitely polarized light; a polarization beam splitter; an optical modulation device including (a) a first film forming a first state and a second state depending on an electric field applied thereto, the first state causing birefringence and the second state not causing birefringence respectively of polarized light from the polarization beam splitter, the first film having a thickness for functioning as a halfwave plate in its first state, (b) a second film of a polymer not causing birefringence of light having passed through the second state of the first film but causing birefringence of light having passed through the first state of the first film, the second film having a thickness set for functioning as a quarter wave plate that is not driven when the first film is set in its first state, and (c) a reflection means for reflecting light having passed through the second film again to the second film and the polarization beam splitter; and a voltage application means.
Claim 14
Dependent Claim
171 words
A display apparatus, comprising: a light source for emitting indefinitely polarized light; a polarization beam splitter; an optical modulation device including (a) a first film forming a first state and a second state depending on an electric field applied thereto, the first state causing birefringence and the second state not causing birefringence respectively of polarized light from the polarization beam splitter, the first film having a thickness for functioning as a halfwave plate in its first state, (b) a second film of a polymer not causing birefringence of light having passed through the second state of the first film but causing birefringence of light having passed through the first state of the first film, the second film having a thickness set for functioning as a quarter wave plate that is not driven when the first film is set in its first state, and (c) a reflection means for reflecting light having passed through the second film again to the second film and the polarization beam splitter; and a voltage application means.
Claim 15
Dependent Claim
14 words
An apparatus according to claim 12, wherein said first film comprises a liquid crystal.
Claim 16
Dependent Claim
18 words
An apparatus according to claim 13, wherein said liquid crystal is a chiral smectic liquid crystal having bistability.
Claim 17
Dependent Claim
15 words
An apparatus according to claim 12, wherein said second film comprises a polymer liquid crystal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-02-20 | 1998-08-22 | 1999-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-02-20 | 2002-08-22 | 2003-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-02-20 | 2006-08-22 | 2007-02-21 | $7700.00 | Window Closed / Lapsed |