Erasable thermo-optic storage display of a transmitted color image
First Claim
1. A device for the projection of color images transmitted under the form of a video-signal, comprising:
- control means for receiving said video signal and supplying three chrominance signals, synchro pulses and erasing pulses;
intermediary display means for inscribing, storing and erasing three chrominance images under the control of said control means and including;
at least one display cell;
said display cell comprising one layer of a material having a smectic phase;
said layer being maintained at a first constant temperature to be in said smectic state; and
one pair of transparent electrodes;
said electrodes enclosing said layer for receiving at least one of said three chrominance signals and said erasing pulses; and
optical recording means controlled by said synchro-pulses for providing at least one luminous spot of substantially constant intensity;
said luminous spot scanning said layer with substantially uniform scanning rate for temporarily heating successively each point thereof from said first constant temperature to a second constant temperature at which said layer is an isotropic liquid state;
said three chrominance images consisting in local variations in the scattering effect of said layer;
illumination means for illuminating said three chrominance images with white light and thus generating three chrominance beams;
optical filtering means for selecting in each said chrominance beam the spectral band associated to said chrominance image;
reflective means for combining said three chrominance beams into a single combined beam; and
projection means for receiving said single combined beam and illuminating a receiving surface with said color images.
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Abstract
The invention provides an optical display device, utilizing a thermo-optical effect to inscribe a transmitted image in a layer of a material exhibiting a smectic state. Recording of the image with a full range of half tones without modulation of the recording beam and quick erasure of the recorded image without reheating of the film can be obtained by directly applying, simultaneously to the whole of the film either the video signal or an erasure voltage of suitable values. By associating this display device to a projection device utilizing a very bright source, the image thus recorded can be projected onto a large screen or a photosensitive substrate. The invention also describes a color images teleprojection and telereproduction device, in which three distinct chrominance images are recorded in a smectic layer as above described and simultaneously illuminated with white light; the three beams thus obtained are filtered for respectively selecting in each of them the spectral band corresponding to the chrominance of the image and superimposed in a single beam by a reflecting system. An objective lens supplied with a diaphragm in its image focal plane receives this single beam and projects the reconstituted colour image onto a screen or a photo-sensitive layer.
62 Citations
12 Claims
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1. A device for the projection of color images transmitted under the form of a video-signal, comprising:
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control means for receiving said video signal and supplying three chrominance signals, synchro pulses and erasing pulses; intermediary display means for inscribing, storing and erasing three chrominance images under the control of said control means and including; at least one display cell;
said display cell comprising one layer of a material having a smectic phase;
said layer being maintained at a first constant temperature to be in said smectic state; and
one pair of transparent electrodes;
said electrodes enclosing said layer for receiving at least one of said three chrominance signals and said erasing pulses; andoptical recording means controlled by said synchro-pulses for providing at least one luminous spot of substantially constant intensity;
said luminous spot scanning said layer with substantially uniform scanning rate for temporarily heating successively each point thereof from said first constant temperature to a second constant temperature at which said layer is an isotropic liquid state;said three chrominance images consisting in local variations in the scattering effect of said layer; illumination means for illuminating said three chrominance images with white light and thus generating three chrominance beams; optical filtering means for selecting in each said chrominance beam the spectral band associated to said chrominance image; reflective means for combining said three chrominance beams into a single combined beam; and projection means for receiving said single combined beam and illuminating a receiving surface with said color images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for projecting color images transmitted under the form of a video-signal, consisting in:
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extracting three chrominance signals from said video-signal; forming three chrominance images under the form of a durable spatial modulation of the light-scattering effect of at least one layer of a material having a smectic state;
said chrominance image being obtained by applying at least one of said chrominance signals to the whole of said layer;
each point of said layer being, in synchronism with said chrominance signal, successively submitted to a temporary heating, from a first temperature at which said layer is in said smectic state, to a second temperature at which said layer is in an isotropic liquid state;
said durable spatial modulation occuring under the control of said chrominance signal during the consecutive cooling of said point from said second to said first temperature;projecting white light for illuminating said three chrominance images and producing three chrominance beams emanating therefrom; filtering said three chrominance beams for selecting in each of them a spectral band respectively corresponding to said chrominance images; superimposing said three chrominance beams for forming a single beam; projecting said single beam for illuminating a receiving surface with said color images. - View Dependent Claims (11, 12)
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Specification