EP0495616A2 - Lesbare Anzeigevorrichtung - Google Patents

Lesbare Anzeigevorrichtung Download PDF

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Publication number
EP0495616A2
EP0495616A2 EP92300290A EP92300290A EP0495616A2 EP 0495616 A2 EP0495616 A2 EP 0495616A2 EP 92300290 A EP92300290 A EP 92300290A EP 92300290 A EP92300290 A EP 92300290A EP 0495616 A2 EP0495616 A2 EP 0495616A2
Authority
EP
European Patent Office
Prior art keywords
light
legend plate
light source
coloured filter
legend
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92300290A
Other languages
English (en)
French (fr)
Other versions
EP0495616A3 (en
Inventor
Lawrence E. Tannas, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Illinois Tool Works Inc
Original Assignee
Illinois Tool Works Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Illinois Tool Works Inc filed Critical Illinois Tool Works Inc
Publication of EP0495616A2 publication Critical patent/EP0495616A2/de
Publication of EP0495616A3 publication Critical patent/EP0495616A3/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F13/00—Illuminated signs; Luminous advertising
    • G09F13/04—Signs, boards or panels, illuminated from behind the insignia
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F13/00—Illuminated signs; Luminous advertising
    • G09F13/04—Signs, boards or panels, illuminated from behind the insignia
    • G09F13/0418—Constructional details
    • G09F13/0472—Traffic signs
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F13/00—Illuminated signs; Luminous advertising
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F13/00—Illuminated signs; Luminous advertising
    • G09F13/04—Signs, boards or panels, illuminated from behind the insignia
    • G09F13/0418—Constructional details
    • G09F2013/05—Constructional details indicating exit way or orientation

Definitions

  • This invention relates generally to visual display device and more particularly, it relates to an improved display structure which is readable even in direct sunlight.
  • the present invention has particular applications for use in instrument panels in aircraft cockpits, automobiles, and other vehicles wherein the display should be readable even in direct sunlight and preferably be unaffected by the phenomenon known as "washout.”
  • LED light-emitting diodes
  • display devices While there is also generally known of various display devices which use light-emitting diodes (LED) as a light source so as to reduce power consumption, such display devices have not been utilized to any large extent due to the fact that they still have the drawback of being "washed out” in direct sunlight.
  • LED light-emitting diodes
  • a liquid crystal display which includes a layer of liquid crystal material disposed between first and second transparent parallel plates to provide a sandwich structure through which light can pass.
  • a third transparent plate of a glass/plastic material has a diffuse surface on its forward face and a metal layer disposed on its other side having high reflectivity characteristics. Ambient light which has passed through the liquid crystal material is reflected from the metal layer and is passed back through the liquid crystal material so as to increase the contrast.
  • a traffic signal light which is comprised of a light source and a liquid crystal means.
  • a transparent colored plate is positioned in front of the light source and is coated with a transparent light-scattering paint to enhance contrast in sunlight.
  • a control circuit applies an electric field to both the liquid crystal means and the light source so that they are energized or de-energized simultaneously.
  • a light transparent layer having a light-reflecting film is disposed between the transparent colored plate and the light source so as to increase the visual distinguishability of the colored plate under direct sunlight.
  • a display structure which is readable even in direct sunlight, comprising: reflector means; light source means including an LED array having a diffusion medium disposed on its front portion for radiating a light when energized; a coloured filter arranged in front of the media of said LED array for transmitting the light radiated from said LED array; a legend plate disposed in front of said coloured filter and having a transparent image of displayable information against an opaque background or vice versa deposited thereon; and, electro-optic shutter means disposed in front of said legend plate for permitting the displayable information on said legend plate to be viewed only when said LED array and said shutter means are energized; is characterized in that the light source means is disposed in front of said reflector means and said reflector means and said diffusion medium reflecting incident sunlight which has passed through said shutter means, legend plate, and coloured filter back through said coloured filter, legend plate, and out said shutter means, whereby the contrast of said displayable information on said legend plate is enhanced rather than being washed out by incident sunlight.
  • the light transmissive/reflective component between the light source and legend can be eliminated by utilizing a diffusion medium in front of the LED light source and a reflector behind the LED.
  • the reflector functions to reflect incoming sunlight back through the filter and legend.
  • the diffusion medium and the reflector cause the reflected light to be lambertion and the LED light to be lambertion.
  • None of the known display device techniques makes use of the reflective properties behind the light source such as an LED array so as to reflect incident sunlight back out.
  • the elimination of the reflective surface or partially reflective surface from the front of the LED allows more of the LED light to exit out the front and makes the display more efficient.
  • the inventors have found that the readability of the display structure can be enhanced through the inclusion of a reflective element positioned behind the LED light source. This element may also scatter light to improve viewing angle and uniformity.
  • the rear side of the legend plate can be provided with a reflective material in the opaque regions so as to reflect light striking the rear of the legend plate back into the interior of the display structure for reflection out the transparent region of the legend. This further conserves light energy.
  • the filter is preferably selected to provide a desired transmittance dependent upon the emission spectral characteristics of both the LED light source and the ambient sunlight. This is done so as to prevent "washout," thus the output colour having the desired chromaticity will be observed by the viewer. In this manner, there is achieved an improved display structure which is compact, has high reliability and is formed of fewer components compared to the various known and proposed display devices.
  • the present invention provides an improved display structure which is readable in the dark and in direct sunlight without colour shift when ON and is unaffected by "washout." Further, the legend and the legend colour is completely unreadable in any ambient illumination including direct sunlight when it is intended to be OFF. Also it is compact, lightweight, power efficient, has high reliability, and is forced of fewer components than those traditionally available. Further the readability of a display structure is enhanced even in direct sunlight by preventing the colour of the legend image from shifting or becoming desaturated.
  • the display structure 10 is comprised of a layered structure which includes an electro-optic shutter 12, a legend plate 14, a colored filter 16, a low-powered light source 18, and a back reflector 42, all contained within a housing or casing 20.
  • the electro-optic shutter 12 is preferably formed of a layer of liquid crystal material which is of the phase change guest-host type. This type of liquid crystal made is referred to in the literature as the Taylor and White made in honor of the inventors. In the energized condition, a power supply (not shown) is applied across electrical leads 22, 24 ( Figure 2) so as to cause the molecules to become aligned and thus permit the passage of light.
  • the electro-optic shutter 12 is similar to the type 103-9 which is manufactured and sold by Hercules.
  • the legend plate 14 is disposed adjacent and behind the inner surface of the layer of liquid crystal material 12.
  • the legend plate 14 is formed with, or has deposited thereon, a transparent area image of the alphanumeric or graphic information, designated generally as displayable information represented in Figure 4 by a message "IMAGE.”
  • the part of the legend plate that is not transparent must be made opaque. This will give a bright image on a dark background.
  • the transparent and opaque areas can be reversed so as to provide a dark image on a bright background.
  • the bright area is made bright by the light from the LED and, if present, the ambient illumination.
  • the back side or rear surface of the legend plate that is in the opaque area may be coated with a transparent light-reflecting film material 14a, which absorbs little light.
  • any light striking the back side of the legend plate opaque area will not be absorbed but will be reflected back into the interior of the display structure and then subsequently further reflected and scattered back through the filter 16 and the legend plate 14. This serves to conserve the light energy from the LED and helps prevent the display from becoming hot to touch or overheated.
  • the filter 16 is arranged behind the inner surface of the legend plate 14 and is fabricated of selected characteristics such that the alphanumeric or graphic information depicted in Figure 4 as IMAGE will appear illuminated as a desired transmission color to the viewer.
  • the colored filter In order to obtain this desired color output of chromaticity without a color shift even under varying ambient (sunlight) intensity conditions, the colored filter must be designed to have certain spectral transmission characteristics (transmissivity).
  • the color filter can be selected from commercially available filters to match available LED colors to achieve acceptable usable colors, based upon conditions and criteria, as discussed below.
  • These filters may be of the industrial grade, in production such as manufactured and sold by Hoya, such as red type R-60.
  • the filter is selected to match available LED colors such as Hewlett-Packard type HLCP-HL100.
  • the advantage to this latter approach is its low cost due to the use of the existing production filters at production thicknesses, and the disadvantage is that there may be a slight color shift due to the limited available filters when the ambient illumination (sunlight) increases in intensity and the color selection is somewhat limited by the available LED colors.
  • a first color output of chromaticity coordinates x1 and y1 must be measured when the LED light source is activated and no sunlight exists.
  • a second color output of chromaticity coordinates x2 and y2 must be measured in the presence of ambient illumination and the LED light source is inactivated.
  • the transmittance of the colored filter can be determined when the following factors are known: (1) emission spectral characteristics of the LED light source; (2) emission spectral characteristics of the ambient illumination; and (3) the desired output color with chromaticity coordinates x3 and y3. From a practical standpoint, it is necessary that the emission spectrum of the LED light source overlap the chromaticity coordinates of the desired output color. Further, it is helpful if the ambient illumination has a broad bandwidth such as exist with sunlight.
  • the desired output color with chromaticity coordinates x3 and y3 will remain substantially the same for any combination of the LED light source and the ambient illumination.
  • the filter transmittance can be computed using optical design computer programs by one skilled in the art. Due to the cost of the filters and the limited availability of LED colors as suggested above, the design was achieved as follows:
  • the chromaticity of the LED light source and the reflected light of the LED light source passing through the colored filter 16 and the legend plate 14 and out the electro-optic shutter 12 will be substantially the same as the chromaticity of the ambient illumination (sunlight) passing through the electro-optic shutter 12, the legend plate 14 and colored filter 16 and reflected back again through the colored filter, legend plate and out the electro-optic shutter. Consequently, the colored filter selected based upon this afore-mentioned technique will be optimized so that the light having the desired output color of chromaticity will be transmitted, thereby insuring image (or contrast) enhancement of display structure even in the presence of sunlight.
  • a first seal 36 functioning as an optical coupling is interposed between the inner surface of the layer 12 of liquid crystal material and the legend plate 14.
  • a second seal 38 functioning as an optical coupling is interposed between the inner surface of the legend plate 14 and the colored filter 16.
  • a third seal 40 functioning as an optical coupling is interposed between the inner surface of the colored filter 16 and the LED media 28 of the light source.
  • the edges and the bottom of the assembly are painted with a white reflective paint to prevent any light loss and reflect inward all light so that it will exit the image area.
  • the assembly of the layer of liquid crystal material, legend plate, colored filter and light source is installed snugly against adjacent surfaces in the casing 20 so as to eliminate unwanted reflection of incident sunlight along the edges of the casing which might decrease the image contrast.
  • the light-scattering element may be preferably formed of a layer of light-scattering paint, glass, plastic or some other diffusive material.
  • the light-scattering material is suitably applied by coating the inner back surface of the casing 20 directly behind the LED light source 18.
  • a light-scattering material may be applied to the entire inside wall surfaces of the casing 20 so as to provide a diffusive condition.
  • the low-powered light source 18 is preferably formed of a light-emitting diode (LED) array 26 having the diffusion medium 28 disposed on its front portion.
  • the medium 28 is transparent plastic and has scattering optical characteristics to diffuse the light coming from the points of each diode in the array 26 into a uniform film of light emitting from the source 18.
  • the inventive concept described herein requires the reflector 42 to be behind the light source 18 for the best results as opposed to a transmissive/reflective component (transflector) placed in front of the light source 18 as found in prior art patent Nos. 4,315,258; 4,791,418; and 4,799,050.
  • This reflector 42 serves to eliminate the necessity of a separate light transmissive/reflective component between the light source and the filter which causes a reduction in the efficiency of the LED array 26.
  • the light source 18 with back reflector 42 and electrical leads 30 and 32 is of the type similar to HLCP H100 and HLMP-2685 which are commercially available from Hewlett Packard.
  • the Hewlett Packard components HLCP H100 and HLMP-2685 are manufactured with the medium 28, the LED array 26, and back reflector 42 with power leads 30 and 32 all in one assembly.
  • the light source 18 further includes electrical leads 30, 32 for receiving power from the power supply.
  • the LED array 26 is de-energized and the layer of liquid crystal material is in the,OFF condition.
  • the displayable information defined by the symbol IMAGE on the legend plate 14 will not be visually observable by the viewer in front of the display structure 10, as shown in Figure 3.
  • the front of the display structure 10 presents a so-called "dead-face.”
  • the ambient sunlight 34 from the viewer's side of the display structure 10 will be passed through the layer 12 of liquid crystal material which is in the ON condition.
  • the legend plate 14 After subsequently passing through the legend plate 14, the colored filter 16, and the medium 28, then reflected back from the element 42, this will cause the ambient sunlight to be dispersed and reflected back through the medium 28, colored filter 16, legend plate 14, and the layer 12 of liquid crystal material and towards the viewer.
  • the light generated by the LED array 26 and the LED light as reflected by the light-scattering element 42 will pass through the medium 28, colored filter 16, legend plate 14, and the layer 12 of liquid crystal material towards the viewer.
  • the colored filter 16 Since the colored filter 16 has been chosen to have a desired transmittance dependent upon both the emission spectrum of the LED light source 18 and the emission spectrum of the ambient sunlight 34 rather than being matched only to the emissivity of the LED light source, the final transmission of the visible light from the colored filter 16 will be at the chromaticity of the desired output color. Therefore, the displayable information represented by the message IMAGE being visible through the layer 12 of liquid crystal material is enhanced rather than being "washed out” and appears to the viewer with the desired transmission color and at a higher luminescence in proportion to the ambient illumination.
  • the present invention provides an improved display structure readable even in direct sunlight, which includes an LED array with a front diffusion medium and a back reflective layer.
  • the reflection/diffusion media reflects and scatters incident sunlight which is passed through a layer of liquid crystal material, legend plate, and colored filter back through the colored filter, legend plate and out the layer of liquid crystal material by using the reflective characteristics of the layer 42 so as to enhance rather than washout the contrast of the displayable information on the legend plate.
  • the colored filter is selected to have certain spectral transmission characteristics dependent upon the emission spectrum of the LED light source, the emission spectrum of the ambient sunlight, and the desired transmission color.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Liquid Crystal (AREA)
  • Led Device Packages (AREA)
EP19920300290 1991-01-15 1992-01-14 Readable display stucture Withdrawn EP0495616A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US64118491A 1991-01-15 1991-01-15
US641184 1991-01-15

Publications (2)

Publication Number Publication Date
EP0495616A2 true EP0495616A2 (de) 1992-07-22
EP0495616A3 EP0495616A3 (en) 1993-02-03

Family

ID=24571288

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920300290 Withdrawn EP0495616A3 (en) 1991-01-15 1992-01-14 Readable display stucture

Country Status (4)

Country Link
EP (1) EP0495616A3 (de)
JP (1) JPH07302053A (de)
KR (1) KR950004717B1 (de)
CA (1) CA2059157A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2711827A1 (fr) * 1993-10-22 1995-05-05 Guigan Franck Système d'affichage.

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016183059A1 (en) * 2015-05-11 2016-11-17 Corning Incorporated Surface display units with opaque screen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2056067A (en) * 1979-08-02 1981-03-11 Rau Swf Autozubehoer Display system especially for motor vehicles
DE3710551A1 (de) * 1987-03-30 1988-10-13 Miditec Mikroelektronik Displa Display fuer variable anzeige
US4791418A (en) * 1986-04-30 1988-12-13 Taliq Corporation Signal light

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5146000U (de) * 1974-10-04 1976-04-05
JPS5492229A (en) * 1977-12-28 1979-07-21 Minolta Camera Co Ltd Flashing display device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2056067A (en) * 1979-08-02 1981-03-11 Rau Swf Autozubehoer Display system especially for motor vehicles
US4791418A (en) * 1986-04-30 1988-12-13 Taliq Corporation Signal light
DE3710551A1 (de) * 1987-03-30 1988-10-13 Miditec Mikroelektronik Displa Display fuer variable anzeige

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DISPLAYS vol. 9, no. 2, April 1988, GUILDFORD,SURREY,GR. BRITAIN pages 85 - 87 PETER KRISTUFEK 'Back lighting Argus LEDs' *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2711827A1 (fr) * 1993-10-22 1995-05-05 Guigan Franck Système d'affichage.

Also Published As

Publication number Publication date
KR950004717B1 (ko) 1995-05-04
KR920015148A (ko) 1992-08-26
CA2059157A1 (en) 1992-07-16
JPH07302053A (ja) 1995-11-14
EP0495616A3 (en) 1993-02-03

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