US4368386A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid-crystal image converter device
Assignee: Thales SA
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Filing: 1981-02-03
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Granted: 1983-01-11
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Expires: 2001-02-03
Abstract
Abstract The invention provides an image converter device which utilizes a liquid crystal cell in which a layer of a nematic material or a nematic-cholesteric mixture is enclosed between a first plate of a photoconductive material, provided with an external electrode, and a second transparent plate, provided with an internal electrode. The photoconductive material may be bismuth oxide, or a mixture of the latter with germanium or silicon oxide. A direct or alternative voltage is applied between the electrodes. An X-rays image, or an image displayed on the screen of a C.R. tube is projected onto the photoconductive plate whose conductivity, thus spatially modulated, causes a spatially variable voltage to be applied in the liquid crystal layer. Various electro-optical effects, such as dynamic scattering, controlled birofringence or controlled rotatory polarization in a twisted structure, can be used to make the projected image to appear in the liquid crystal layer illuminated by a visible light read-out beam and be directly observed or enlarged by projection onto a screen.
Inventors
- 👤 Jean-Pierre Huignard
- 👤 Serge Le Berre
- 👤 Christian Mayeux
- 👤 Francois Micheron
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:19
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/135
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
175 words
An image converter device for receiving an image projected by a write-in radiation and reading said image by a read-out radiation of visible light, comprising: a liquid crystal layer wherein said image is at least temporarily inscribed for being read by said read-out radiation, said layer at least including a mesomorphic material having a nematic phase and being in an initial uniform orientation in the absence of said write-in radiation; a first and second self supporting slab enclosing and completely supporting said layer; said first slab being 0.5 to 1 mm in thickness consisting of material which is photoconductive under the action of said write-in beam and being arranged for receiving said projected image; said second slab being transparent to said read-out radiation; a first and a second electrode respectively arranged on the external face of said photoconductive first slab and the internal face of said transparent second slab and respectively transparent to said write-in and said read-out radiation; voltage generating means for at least applying a control voltage between said first and second electrodes.
Claim 2
Dependent Claim
175 words
An image converter device for receiving an image projected by a write-in radiation and reading said image by a read-out radiation of visible light, comprising: a liquid crystal layer wherein said image is at least temporarily inscribed for being read by said read-out radiation, said layer at least including a mesomorphic material having a nematic phase and being in an initial uniform orientation in the absence of said write-in radiation; a first and second self supporting slab enclosing and completely supporting said layer; said first slab being 0.5 to 1 mm in thickness consisting of material which is photoconductive under the action of said write-in beam and being arranged for receiving said projected image; said second slab being transparent to said read-out radiation; a first and a second electrode respectively arranged on the external face of said photoconductive first slab and the internal face of said transparent second slab and respectively transparent to said write-in and said read-out radiation; voltage generating means for at least applying a control voltage between said first and second electrodes.
Claim 3
Dependent Claim
19 words
A device as claimed in claim 1, wherein said photoconductive slab is made of a material containing bismuth oxide.
Claim 4
Dependent Claim
17 words
A device as claimed in claim 2, wherein said bismuth oxide containing material further contains silicon oxide.
Claim 5
Dependent Claim
17 words
A device as claimed in claim 2, wherein said bismuth oxide containing material further contains germanium oxide.
Claim 6
Dependent Claim
15 words
A device as claimed in claim 2, wherein said bismuth oxide containing material is monocrystalline.
Claim 7
Dependent Claim
18 words
A device as claimed in claim 2, wherein said bismuth oxide containing material is a sintered polycrystalline material.
Claim 8
Dependent Claim
52 words
A device as claimed in claim 1, wherein said voltage generating means, comprising means for control voltage causing a voltage greater than the threshold voltage of the dynamic scattering effect to be applied to at least part of the points of the liquid crystal layer in the presence of said write-in radiation.
Claim 9
Dependent Claim
83 words
A device as claimed in claim 1, wherein said read-out radiation is polarized radiation, said device further comprising a polarized light analyzer arranged opposite to the external face of said transparent slab, said liquid crystal layer being in nematic phase, said control voltage comprising means for causing a voltage greater than the threshold voltage above which said initial orientation is modified to be applied to at least part of the points of the liquid crystal layer in the presence of said write-in radiation.
Claim 10
Dependent Claim
32 words
A device as claimed in claim 1, wherein said first slab has a light absorption coefficient at most equal to 100 cm -1 and at least equal to 0.5 cm -1 .
Claim 11
Dependent Claim
36 words
A device as claimed in claim 8, wherein said liquid crystal layer, when in initial uniform orientation, has a twisted structure, said read-out radiation being a linearly polarized radiation and said analyzer comprising a linear analyzer.
Claim 12
Dependent Claim
22 words
A device as claimed in claim 1, wherein said read-out radiation passes through said photoconductive slab before reaching said liquid crystal layer.
Claim 13
Dependent Claim
28 words
A device as claimed in claim 11, wherein the spectral region to which the photoconductive material is sensitive is different form the spectral region of the read-out radiation.
Claim 14
Dependent Claim
67 words
A device as claimed in claim 11, wherein the spectral region to which the photoconductive material is sensitive has a part in common with the spectral region of the read-out radiation, said control voltage comprising means for causing an uniform voltage greater than a threshold voltage to be applied to the whole liquid crystal layer illuminated by said read-out radiation in the absence of said write-in radiation.
Claim 15
Dependent Claim
26 words
A device as claimed in claim 1, further comprising a layer reflecting said read-out radiation and arranged between said photoconductive slab and said liquid crystal layer.
Claim 16
Dependent Claim
17 words
A device as claimed in claim 1, further comprising an X-rays source for emitting said write-in radiation.
Claim 17
Dependent Claim
43 words
A device as claimed in claim 1, wherein said write-in radiation is the radiation emanating from the moving spot of a cathodic tube screen, and said device further comprising optical projecting means for projecting the image of said spot onto said photoconductive slab.
Claim 18
Dependent Claim
54 words
A device as claimed in claim 1, which further comprises a light source for emitting said read-out radiation, optical collimating means for receiving said read-out radiation and illuminating said liquid crystal layer with parallel beam and image formation optical means for projecting the image inscribed in said liquid crystal layer onto a receiving surface.
Claim 19
Dependent Claim
15 words
A device as claimed in claim 17 wherein said receiving surface is a photosensitive surface.
Claim 20
Dependent Claim
18 words
A device as claimed in claim 7, wherein said layer includes a mesomorphic material having a cholesteric phase.
Claim 21
Dependent Claim
29 words
A device as claimed in claim 1 or 9, wherein said first slab has a thickness at most equal to 0.8 mm and at least equal to 0.1 mm.
Claim 22
Dependent Claim
181 words
An image converter device for receiving an image projected by a write-in radiation and reading said image by a read-out radiation of visible light, comprising: a liquid crystal layer wherein said image is at least temporarily inscribed for being read by said read-out radiation, said layer at least including a mesomorphic material having a nematic phase and being in an initial uniform orientation in the absence of said write-in radiation; a first and second self-supporting slab enclosing and completely supporting said layer; said first slab being 0.5 to 1 mm in thickness consisting of material which is photoconductive under the action of said write-in beam and being arranged for receiving said projected image; said photoconductive material containing bismuth oxide; said second slab being transparent to said read-out radiation; a first and a second electrode respectively arranged on the external face of said photoconductive first slab and the internal face of said transparent second slab and respectively transparent to said write-in and said read-out radiation; and voltage generating means for at least applying a control voltage between said first and second electrodes.
Claim 23
Dependent Claim
181 words
An image converter device for receiving an image projected by a write-in radiation and reading said image by a read-out radiation of visible light, comprising: a liquid crystal layer wherein said image is at least temporarily inscribed for being read by said read-out radiation, said layer at least including a mesomorphic material having a nematic phase and being in an initial uniform orientation in the absence of said write-in radiation; a first and second self-supporting slab enclosing and completely supporting said layer; said first slab being 0.5 to 1 mm in thickness consisting of material which is photoconductive under the action of said write-in beam and being arranged for receiving said projected image; said photoconductive material containing bismuth oxide; said second slab being transparent to said read-out radiation; a first and a second electrode respectively arranged on the external face of said photoconductive first slab and the internal face of said transparent second slab and respectively transparent to said write-in and said read-out radiation; and voltage generating means for at least applying a control voltage between said first and second electrodes.
Claim 24
Dependent Claim
18 words
A device as claimed in claim 21, wherein said bismuth oxide containing material is a sintered polycrystalline material.
Claim 25
Dependent Claim
17 words
A device as claimed in claim 21, wherein said bismuth oxide containing material further contains silicon oxide.
Claim 26
Dependent Claim
17 words
A device as claimed in claim 21, wherein said bismuth oxide containing material further contains germanium oxide.
Claim 27
Dependent Claim
15 words
A device as claimed in claim 21, wherein said bismuth oxide containing material is monocrystalline.
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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) | 1986-01-10 | 1986-07-12 | 1987-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-10 | 1990-07-12 | 1991-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-10 | 1994-07-12 | 1995-01-11 | $7700.00 | Window Closed / Lapsed |