Indicator device having electro-optical light valve unit

Claim 1

An indicating device having an electro-optical light valve unit whose front surface is in optical contact with a fluorescent plate, said plate consisting of a material with a refraction of index larger than 1 and containing fluorescent particles creating a fluorescent light which is emitted toward the front of the light value when excited by a given range of wavelengths of ambient light, said fluorescent plate being provided on its edges with means for reflecting light the improvement comprising a contrast filter being arranged behind the light valve unit and fluorescent plate in a direction of viewing, said contrast filter transmitting light of the given range of wavelengths and absorbing the light of the frequency range emitted by the fluorescent particles, and a reflector being disposed behind the contrast filter so that light of the given range of wavelengths passing through the light valve unit and the fluorescent plate is reflected by the reflector back into the plate.

Claim 20

A method of operating an optical display device having a high contrast and light intensity of the image being displayed relative to the background light, said display device comprising a liquid crystal cell having a layer of liquid crystal material interposed between spaced apart front and rear transparent carrier plates, said carrier plates on their inner surfaces facing the layer of the liquid crystal material being provided with transparent conductive coatings to form electrodes with at least one of said coatings being interrupted to provide a plurality of separable, excitable electrodes and a fluorescent plate of material with an index of refraction greater than one, said material having fluorescent particles for creating fluorescent light from an excitation frequency of the ambient light, said plate being disposed in front of the liquid crystal cell in contact therewith, a contrast filter disposed behind the liquid crystal cell for absorbing light of the frequency range of the fluorescent light and passing light of the excitation frequency spectrum, a reflector disposed behind the filter for reflecting light of the excitation frequency back into the plate, said method comprising selectively applying an electrical voltage to the electrodes of the front and back plates to selectively change the optical properties of the liquid crystal layer disposed therebetween to create light images on the colored background of the filter.

Claim 21

A method of operating an optical display device having a high contrast and light intensity of the image being displayed relative to the background light, said display device comprising a liquid crystal cell having a layer of liquid crystal material interposed between spaced apart front and rear transparent carrier plates, said carrier plates on their inner surfaces facing the layer of the liquid crystal material being provided with transparent conductive coatings to form electrodes with at least one of said coatings being interrupted to provide a plurality of separable, excitable electrodes and a fluorescent plate of material with an index of refraction greater than one, said material having fluorescent particles for creating fluorescent light from an excitation frequency of the ambient light, said plate being disposed in front of the liquid crystal cell in contact therewith, a contrast filter disposed behind the liquid crystal cell for absorbing light of the frequency range of the fluorescent light and passing light of the excitation frequency spectrum, a reflector disposed behind the filter for reflecting light of the excitation frequency back into the plate, said method comprising selectively applying an electrical voltage to the electrodes of the front and back plates to selectively change the optical properties of the liquid crystal layer disposed therebetween to create light images on the colored background of the filter.