EP0136085A1
Expired / Lapsed
EP
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Apparatus for influencing the presentation of visual information
Assignee: Canadian Industrial Innovation Centre
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Filing: 1984-08-24
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Granted: —
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Expires: 2004-08-24
Abstract
Abstract @ An electro-optical device for influencing the presentation of visual information when placed before the eyes of an observer, comprising one or more cholesteric liquid crystal cells (3) which, under the control of an electric driving signal, can be rapidly switched, by means of the cholesteric-nematic phase change effect, between a clear, transparent texture and a cloudy, scattering texture. The invention is particularly suited for application as a spectacle-mounted stroboscope, tachistoscope or stereoscopic viewer, wherein special features are the absence of colour distortion, the continued illumination of the eye during occlusion and the very high switching speeds.
Inventors
- 👤 Paul Milgram
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 06:33
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/13731; G02F1/133; G02F1/13306; G02F1/13756
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
205 words
A device for influencing visual information presented to at least one eye of at least one observer, wherein a shutter apparatus is placed between the relevant eye of the observer and the source of the visual information, characterized in that said shutter apparatus comprises one or more liquid crystal cells (3), each comprising a layer of cholesteric liquid crystal material (4) enclosed by two parallel plates of glass (5), whereby each plate of glass is coated on the side adjacent to the layer of liquid crystal with an electrode coating (6), being a film of transparent electrically conductive material, whereby each coating is electrically insulated from the other and is connected to a voltage source (10) by means of which an electric field can be imposed across the liquid crystal cell and by means of which the light transmission characteristics of the liquid crystal can be regulated, whereby by means of the cholesteric-nematic phase change effect and depending on the imposed electric field incident light can be either scattered by the liquid crystal or allowed to pass unhindered through the shutter apparatus, wherein the transmission and scattering of incident light determines whether visual information is respectively received or occulted at the eye of the observer.
Claim 2
Independent Claim
205 words
A device for influencing visual information presented to at least one eye of at least one observer, wherein a shutter apparatus is placed between the relevant eye of the observer and the source of the visual information, characterized in that said shutter apparatus comprises one or more liquid crystal cells (3), each comprising a layer of cholesteric liquid crystal material (4) enclosed by two parallel plates of glass (5), whereby each plate of glass is coated on the side adjacent to the layer of liquid crystal with an electrode coating (6), being a film of transparent electrically conductive material, whereby each coating is electrically insulated from the other and is connected to a voltage source (10) by means of which an electric field can be imposed across the liquid crystal cell and by means of which the light transmission characteristics of the liquid crystal can be regulated, whereby by means of the cholesteric-nematic phase change effect and depending on the imposed electric field incident light can be either scattered by the liquid crystal or allowed to pass unhindered through the shutter apparatus, wherein the transmission and scattering of incident light determines whether visual information is respectively received or occulted at the eye of the observer.
Claim 3
Dependent Claim
60 words
The device according to claim 1, characterized in that by the imposition of an electric field which is greater than a critical value the shutter apparatus will appear transparent and by the removal of the electric field or by the imposition of an electric field which is less than said critical value the shutter apparatus will acquire a scattering texture.
Claim 4
Dependent Claim
87 words
The device according to claim 2, characterized in that the voltage source is constructed such that, when enabled by a gating signal, across each cell an electric field is imposed which is initially considerably greater than the critical field necessary for changing the phase of the liquid crystal from scattering to transparent and such that after the transition said electric field can then be reduced to a level which is closer to the critical field value and sufficiently above said field value to maintain the transparent phase.
Claim 5
Dependent Claim
27 words
The device according to claim 3, characterized in that each shutter apparatus consists of one or more liquid crystal cells which are placed with their surfaces contiguous.
Claim 6
Dependent Claim
65 words
The device according to claim 4, characterized in that the electrode coatings (6) on one or both of the parallel plates (5) in each cell are subdivided into segments, in that each segment is adapted to be connected to a voltage source and in that means are provided, through direct addressing or multiplexing, for switching sections of each cell between the transparent and scattering states.
Claim 7
Dependent Claim
53 words
The device according to claim 4, characterized in that two shutter apparatuses are mounted on one frame, in that one shutter apparatus is situated in front of each eye of an observer wearing the frame and in that the voltage source is constructed such that the two shutter apparatuses can be independently activated.
Claim 8
Dependent Claim
43 words
The device according to claim 6, whereby said device is intended for use as a stroboscope, characterized in that the shutter apparatuses are switched to the transparent state for short periods of time in synchrony with the recurrence of phenomena to be observed.
Claim 9
Dependent Claim
44 words
The device according to claim 6, whereby said device is intended for use as a tachistrscope, characterized in that visual information can be presented to one or both eyes of an experimental subject in a controlled fashion and, especially, for short periods of time.
Claim 10
Dependent Claim
106 words
The device according to claim 5, characterized in that two shutter apparatuses are mounted on a frame, in that one shutter apparatus is situated in front of each eye of an observer wearing the frame, in that the voltage source is constructed such that the two shutter apparatuses can be independently activated and in that said device is intended for use as a tachistoscope, whereby visual information comprising all or part of the visual field of one or both eyes can be presented to or occulted from the corresponding eyes of an experimental subject in a controlled fashion, especially for short periods of time or repetitively.
Claim 11
Dependent Claim
129 words
The device according to claim 6, whereby said device is intended for use as a stereoscopic viewer, characterized in that successively alternating and appropriately differing images are presented on a suitable display device, in that each alternating image is intended for alternating presentation to only one of the observer's eyes, as either a left-eye image or a right-eye image; in that the two shutter apparatuses are synchronously switched such that the left eye of the observer receives only left-eye image information and the right eye of the observer receives only right-eye image information; and in that said display images are alternated at a sufficiently rapid rate to cause the observer to perceive one continuous three dimensional display image, with minimum flicker and no distortion of display image colour content.
Claim 12
Dependent Claim
32 words
The device according to claim 10, characterized in that said display images are generated by a raster scanning device, wherein said left-eye and right-eye images correspond to alternating complete raster scanning frames.
Claim 13
Dependent Claim
20 words
The device according to claim 11, characterized in that the raster scanning device has a faster than normal frame frequency.
Claim 14
Dependent Claim
35 words
The device according to claim 10, characterized in that said display images are generated by a raster scanning device, whereby said left-eye and right-eye images correspond to alternating rational fractions of complete raster scanning frames.
Claim 15
Dependent Claim
27 words
The device according to claim 10, characterized in that said display images are generated by means of the serial generation of individual vector components of said images.
Claim 16
Dependent Claim
18 words
The device according to claim 14, characterized in that said vector components are determined.by a digital computing apparatus.
Claim 17
Dependent Claim
33 words
The device according to claim 10, characterized in that said display images are generated by a continuous stroke writing device, wherein image content is continuously determined by an analog computing or measuring apparatus.
Claim 18
Dependent Claim
21 words
The device according to claim 10, characterized in that said display images are spatial reproductions or projections of said image information.
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