Siemens Aktiengesellschaft

Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Seimens Aktiengesellschaft

Waldemar Greubel

Guenter Baur

Hans Krueger

Ferdinand Quella

Alois Schauer

Hans Kruger

Adolf Goetzberger

Gunter Baur

Rudolf Knauer

A display device for displaying bright images on a dark background, which device includes a liquid crystal cell having a liquid crystal layer with switchable zones between at least two optical states, a light trap in the form of a body exhibiting fluorescent particles and having light emergent windows disposed behind each of the switchable zones in the direction of observation, characterized with the liquid crystal layer containing at least one pleochroic dye. The dye in the liquid crystal layer acting by itself or in conjunction with a polarizer can block passage of the fluorescent light during one optical state of the layer and enable passage of the light during the other state.

Display device for displaying light images on a dark background

A display device includes a light valve that is operated in a time division multiplex method and a fluorescent plate. The light valve may be a liquid crystal with a steep gradient of the contrast-voltage curve so that more multiplex steps are possible. One method of increasing this gradient is to allow only light from a narrow defined spatial angle range to pass through the light valve. In order to produce the narrow light cone that is desired, the invention proposes utilizing a diffusingly reflective layer, which extends parallel to a surface of the fluorescent plate at a finite distance and preferably, the light outlet or exit window of the plate is a surface provided with a dielectric multiple layer which allows the fluorescent light to emerge only in relatively limited spatial angle range. Preferably, these surfaces are the narrow edges of the fluorescent plate.

Display device with a light valve operated in a time division multiplex

A light-collecting device in the form of, for example, a rectangularly-shaped body having a so-called 'fluorescent plate' with at least one light-exit window is comprised of a solid polymerized synthetic carrier material, such as a polyacrylate, a polymethacrylate, a polystyrene or copolymers thereof, containing fluorescing particles therein which have finite dipole moments with different values in the basic and in the excited state and containing a polar organic additive, such as a high-boiling polar solvent, for example, an aliphatic or aromatic alcohol, a nitrile or an ionogenic or non-ionogenic soap, with the fluorescing particles and additive being substantially uniformly distributed throughout such carrier material. The additive creates an environment with an orientating polarization about the fluorescent particles whereby the environment can re-orientate so-quickly that it achieves its thermodynamic equilibrium substantially completely during the existence of the excited state in the fluorescing particles and tends to suppress the disruptive self-absorption of light within the fluorescent plate. Such self-absorption originates from a partial overlap of the emission spectrum with the absorption spectrum of the fluorescing particles. The additive can be dissolved in the synthetic carrier material or can be chemically linked therewith and the so-attained system can be injection moulded, extruded or cast into a desired body form. The disclosed device is useful as a solar collector, an optical indicia transmitter or an image brightener for passive displays.

Device for collecting light and method of manufacturing such device

A light-collecting device in the form of, for example, a rectangularly-shaped body having a so-called 'fluorescent plate' with at least one light-exit window is comprised of a solid polymerized synthetic carrier material, such as a polyacrylate, a polymethacrylate, polystyrene or copolymer of a methacrylate and a styrene containing fluorescing particles therein which have finite dipole moments with different values in the basic and in the excited state and containing an amphiphilic additive, such as an ionoic or non-ionoic or polymeric soap, with such amphiphilic additive being colloidally dissolved in the synthetic carrier in such a manner that the fluorescing particles are each surrounded by one of the colloid particles and an environment with an orientation polarization is attained whereby the environment can re-orientate so quickly that it achieves its thermodynamic equilibrium substantially completely during the existence of the excited state in the fluorescing particles and tends to suppress the disruptive self-absorption of a light within the fluorescent plate. Such self-absorption originates from a partial overlap of the emission spectrum with the absorption spectrum of the fluorescing particles. In certain embodiments of the invention, an additional polar solvent for the fluorescing particles is also enclosed in the colloid particles. The amphiphilic additive and/or polar solvents can be admixed in the synthetic carrier material and the so-attained system can be cast into a desired body form. The disclosed device is useful as a solar collector, an optical indicia transmitter of an image brightener for passive displays.

A light-collecting device in the form of, for example, a rectangularly-shaped body having a so-called 'fluorescent plate' with at least one light-exit window is comprised of a solid carrier material having an index of refraction greater than one, such as a polar, water-containing amorphous material based on a polysilicate or a polyphosphate and containing organic or inorganic fluorescent particles therein, which have finite dipole moments with different values in the basic and the excited state, with the fluorescent particles being substantially uniformly distributed throughout the carrier material. In embodiments where the fluorescent particles are organic, an amphiphilic additive, such as a soap, is colloidally dissolved in the carrier material in such a manner that the fluorescent particles are each surrounded by a colloid particle. The disclosed device is useful as a solar collector, an optical indicia transmitter or an image brightener for passive displays.

Device for collecting light

A display device for representation of a bright image on a background which device has a light valve comprising a liquid crystal cell having a medium which can be switched zone-wise between at least two optical states and a light trap or body which consists of a material having an index of refraction greater than 1, contains a fluorescent material, and is provided with an outlet window for each of the switchable zones characterized by means coacting with the switchable medium to control the passage of the light through the device so that in a rest or inactive state of the medium, the medium and means allow the passage of the excitation light for the fluorescent particles and the passage of the fluorescent light therefrom and in an 'on' or activated state of the medium, the means and medium are impermeable at least to the fluorescent light so that each of the switchable zones of the medium is placed in an 'on' state only when it belongs to the background of the image. The means may be a pleochroic dye operating with a single polarizer or a pair of cross polarizers, which cooperate with the material of the liquid crystal which forms a twisted cell.

Display device for the representation of bright images on a dark

A display device having a liquid crystal cell containing a medium, which can be switched zone-wise between at least two different optical states to form a light valve, a light trap in the form of a plate-shaped body disposed behind the liquid crystal cell when taken in a direction of observation of the device, the plate-shaped body having a material with an index of refraction greater than 1, containing fluorescent particles, and possessing a light emergent or outlet window at the rear of each switchable zone of the liquid crystal cell characterized by the light emergent or outlet windows comprising a groove in the plate and a light scattering surface disposed between the groove and the medium of the liquid crystal cell. Preferably, the grooves of each of the windows is disposed in a rear surface or side of the fluorescent plate and the scattering surface is arranged on a front surface of the plate and can either be formed by a pigment layer which has been silk screened on the front surface or a rough surface zone which has been embossed on the front surface.

Display device comprising a liquid crystal cell with light valves

An improved display device having a light valve unit or display and a fluorescent plate characterized by a frame member for holding the light valve unit and fluorescent plate with the exit windows of the fluorescent plate being aligned with the switchable zones of the light valve unit. Preferably, the frame member will pass light which will excite the fluorescent particles of the fluorescent plate but will not allow passage of the fluorescent light so that a high contrast of the display can be obtained. The frame, which is preferably molded of synthetic plastic, can contain fluorescent particles, which emit light at a frequency range that does not impair the optical contrast of the display and which can be utilized to charge a battery for an auxiliary illumination device.

Display device comprising a light valve unit in conjunction with the

An arrangement or device for optical transmission of communications including a light transmitter with an associated receiver characterized by the receiver having a light collecting body having an index of refraction greater than 1 and containing fluorescent materials which absorb the band of light emitted by the transmitter and create a band of light which is not absorbed by the substance and is detected by the receiver. If more than one transmitter is utilized, they are arranged to transmit in different frequency bands and each transmitter has an associated fluorescent substance which will absorb the discrete separate frequency but not the other frequency bands and emit a fluorescent signal which is only detected by the respective receiver for that transmitter. These fluorescent substances can be in separate light collecting bodies or as a mixture in a single body which has more than one receiver attached thereto.

Arrangement for optical transmission of communications

The present invention provides an apparatus in which one or more light concentrators comprising thin layers of transparent solid or liquid materials with embedded fluorescent centers are combined with absorbers in order to convert solar light into heat energy at high temperatures.

Apparatus for converting light energy into heat energy by light

Electro-optical display device which may operate either in a one or multi-color mode and utilizes electro-optical light valves for controlling transmittance of a passive light through the device characterized by passively amplifying the brightness of the display device with the addition of a light trap which includes a fluorescent plate having mirrored edge surfaces. While the invention or improvement may be utilized with any passive optical display device, it is particularly useful with a liquid crystal display device.

Electro-optical display device with electro-optical light valves

An indicating device for projecting symbols of all kinds characterized by a plate of fluorescent synthetic material having metallized edges to create a light trap for the fluorescent light created in the plate, a layer of light dispersing material mounted in spaced relation to a surface of the plate, contact film disposed at least in selected areas between the layer and plate, means for selectively moving portions of the layer into optical contact with the contact film and plate to cause decoupling of the fluorescent light from the plate. The means for moving includes a plurality of electrodes disposed in the device in a given pattern and means for selectively applying an electrical current to the electrodes to create a selective arrangement of electrical fields to create a display of a desired symbol. The means for moving may be a membrane on which electrodes are disposed to coact with electrodes on the plate to deflect the membrane toward the plate to move the dispersing layer into optical contact with the plate or may be a ceramic plate of ferroelectric material which on the application of electrical current to the electrodes causes a selected expansion of the plate due to remanent electrical polarization to move the layer into contact with the plate of fluorescent synthetic material.

Indicating device for illustrating symbols of all kinds

An apparatus for the conversion of light energy into electrical energy, by hich solar energy may be converted into electrical energy effectively and cheaply. The invention further relates to fluorescent centers (light concentrators) which consist of thin layers of transparent solid or liquid materials with embedded fluorescent centers and which in conjunction with solar cells serve to convert solar energy into electrical energy.

Growing community of inventors

Munich, Germany

Waldemar Greubel