# US 4,394,068 A · Fluorescently activated display device with improved sensitivity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,394,068 A - Document ID: US4394068A - Status: Granted - Kind: A - Application number: 06/121,372 - Filed: 1980-02-14 - Granted: 1983-07-19 - Earliest claimed: 1979-03-20 - Assignees: Siemens Aktiengesellschaft - Inventors: Heinz Pape; Ferdinand Quella; Hans Krueger - Web page: https://patentgrep.com/patent/US4394068A ## CPC - G02F 1/133617: {Illumination with ultraviolet light; Luminescent elements or materials associated to the cell} - G02F 1/0105: {Illuminating devices} - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract An electro-optical display device has a fluorescently activated plate disposed in front of a passive display in the line of sight of a viewer. The entire surface of the fluorescently activated plate is uncovered and is available for collecting ambient light to provide an image of increased intensity and allowing the device to be utilized in environments having low optical radiation levels. The fluorescently activated plate has exit windows thereon for retransmitting the light as controlled by the switchable regions of the passive display in a designated pattern to a viewer. ## Claims ### Claim 1 A device for the optical display of information with improved sensitivity and intensity comprising: a plate consisting of a material with an index of refraction greater than 1 and which contains fluorescent particles for collection of light radiation impinging on said plate by means of fluorescent scattering; a passive display having regions controllably switchable between a light absorbing and a light reflective state, said passive display disposed behind said plate in the line of sight of a viewer; and a coupling means for coupling selected areas of said plate and said passive display to allow transmission of light in selected patterns to a viewer. ### Claim 2 (depends on 1) The device of claim 1 wherein said coupling means is comprised of at least one element comprised of light conducting material disposed between a switchable region of said display and said plate. ### Claim 3 (depends on 1) The device of claim 1 wherein said plate and said display each have at least one flat surface, and wherein said coupling means comprises a plane containing said flat surfaces with said plate and said display disposed adjacently at said flat surfaces. ### Claim 4 (depends on 1) The device of claim 1 wherein said plate is provided with a light exit window in registry with each switchable region of said display. ### Claim 5 (depends on 4) The device of claim 4 wherein said light exit windows are elevations on the fluorescent plate. ### Claim 6 (depends on 5) The device of claim 5 wherein the edges of said elevations are mirrored. ### Claim 7 (depends on 1) The device of claim 1 wherein the edges of said plate are mirrored. ### Claim 8 (depends on 1) The device of claim 1 wherein said coupling means has adhesive properties for maintaining said display and said plate in joined relation. ### Claim 9 (depends on 1) The device of claim 1 wherein said absorbing state is achieved by selected absorption of light radiation, and wherein said absorption in said display occurs at a frequency substantially equivalent to the frequency of fluorescent emission of said fluorescent particles. ### Claim 10 (depends on 1) The device of claim 1 wherein an opaque foil layer is disposed between said plate and said display, said opaque foil covering only regions not coupled by said coupling means. ### Claim 11 (depends on 10) The device of claim 10 wherein said foil layer has a color absorbing light of substantially the same frequency as the absorbing state of said display. ### Claim 12 (depends on 1) The device of claim 1 wherein regions of said display which are not coupled to said plate are of a color absorbing substantially the same frequencies as said light absorbing state in said display. ### Claim 13 (depends on 1) The device of claim 1 wherein regions of said display which are not switchable are mirrored. ### Claim 14 (depends on 1) The device of claim 1 wherein said display is a solid electrochrome display. ### Claim 15 (depends on 1) The device of claim 1 wherein said display is a liquid electrochrome display. ### Claim 16 (depends on 1) The device of claim 1 wherein a separate display is provided for each switchable region, and wherein said separate displays are attached directly to said plate. ### Claim 17 (depends on 15) The device of claim 15 wherein said coupling means has an area which is less than or equal to the switchable region of the electrochrome display. ### Claim 18 (depends on 14) The device of claim 14 wherein said electrochrome display contains an internal diffuse scatterer, and wherein regions of said diffuse scatterer which are not in registry with the switchable regions of said electrochrome display are of a color which absorbs light of substantially the same frequencies as the absorbing state of the electrochrome display. ### Claim 19 (depends on 14) The device of claim 14 wherein said electrochrome display contains an internal diffuse scatterer, and wherein portions of said scatterer in registry with the switchable regions of said electrochrome display contain fluorescent particles. ### Claim 20 (depends on 15) The device of claim 15 wherein said plate forms a front transparent carrier for the electrochrome display electrodes and wherein the rear carrier of the electrochrome display is transparent. ### Claim 21 (depends on 20) The device of claim 20 wherein said rear carrier of electrochrome display contains fluorescent particles. ### Claim 22 (depends on 20) The device of claim 20 wherein the index of refraction of the electrolyte in the electrochrome display is approximately equal to that of the plate. ### Claim 23 (depends on 20) The device of claim 20 wherein the electrochrome display is provided with an internal diffuse scatterer in registry with switchable regions in the electrochrome display. ### Claim 24 (depends on 20) The device of claim 20 wherein the electrolyte for the electrochrome display is transparent. ### Claim 25 (depends on 20) The device of claim 20 wherein the entire electrochrome display including the front and rear carriers are mirrored on their edges. ### Claim 26 (depends on 20) The device of claim 20 wherein the fluorescent particles in said plate are disposed in a flat region thereof closest to a viewer in the viewer's line of sight and wherein the region containing fluorescent particles is substantially thicker than the remaining region of the plate which does not contain fluorescent particles. ### Claim 27 (depends on 26) The device of claim 26 wherein the fluorescent particles in said plate are disposed in a region having a thickness of 2 mm. ### Claim 28 (depends on 20) The device of claim 20 wherein a fluorescing dye is dissolved in the electrolyte of said electrochrome display. ### Claim 29 (depends on 27) The device of claim 27 wherein an internal diffuse scatterer is provided in said electrochrome display in registry with switchable regions of said display, and wherein said diffuse scatterer is colored with a fluorescing dye absorbing different frequencies than the fluorescing dye dissolved in the electrolyte. ### Claim 30 (depends on 1) The device of claim 1, wherein said display is an electrophoretic display. ### Claim 31 (depends on 30) The device of claim 30 wherein the electrophoretic display is black. ### Claim 32 (depends on 30) The device of claim 30 wherein the electrophoretic particles are colored, e.g. white. ### Claim 33 (depends on 32) The device of claim 32 wherein the electrophoretic particles are fluorescing. ### Claim 34 (depends on 1) The device of claim 1 wherein said display is a magnetic dipole display. ### Claim 35 (depends on 34) The device of claim 34 wherein the magnetic particles are colored. ### Claim 36 (depends on 1) The device of claim 1 wherein said display is a colloid suspension display. ### Claim 37 (depends on 36) The device of claim 36 wherein the colloid suspension is comprised of fibres, e.g. carbon or herapatit. ### Claim 38 (depends on 1) The device of claim 1 wherein said display is a pleochroic dyes containing liquid crystal display. ### Claim 39 (depends on 38) The device of claim 38 wherein said dyes are fluorescing. ### Claim 40 (depends on 38) The device of claim 38 wherein the back-plate of the display is covered with fluorescing particles.