WO1994000794A1 - Transmissive display having a controlled spectral output - Google Patents
Transmissive display having a controlled spectral output Download PDFInfo
- Publication number
- WO1994000794A1 WO1994000794A1 PCT/US1993/005987 US9305987W WO9400794A1 WO 1994000794 A1 WO1994000794 A1 WO 1994000794A1 US 9305987 W US9305987 W US 9305987W WO 9400794 A1 WO9400794 A1 WO 9400794A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light
- spectral output
- display apparatus
- display
- lamp
- 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.)
- Ceased
Links
Classifications
-
- 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
- G09F9/35—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 liquid crystals
-
- G—PHYSICS
- G02—OPTICS
- 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
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133609—Direct backlight including means for improving the color mixing, e.g. white
-
- G—PHYSICS
- G02—OPTICS
- 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
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133626—Illuminating devices providing two modes of illumination, e.g. day-night
Definitions
- the present invention relates to transmissive displays, more specifically it relates to backlighting a transmissive display using a spectrally controlled light source.
- Transmissive displays such as liquid crystal displays (LCDs) are used in a variety of applications. Some of these applications include military applications where two modes of operation are required. The first mode comprises providing a color display that enhances the observer's ability to comprehend information, and the second mode comprises a display that can be used while an observer is wearing night vision goggles. Displays suitable for observation through night vision goggles require suppressing the longer wavelengths of light that are produced by the display's backlight. In the past, an optical filter was placed between a full spectrum backlight and the transmissive display seen by the observer. This solution blocked the longer wavdengths and made it possible to produce a display that was compatible with night vision goggles, however, the missing wavelengths degraded the color display that was desired when night vision goggles were unnecessary.
- the present invention provides a transmissive display that has a backlight that uses two or more spectral sources. Each spectral source is tailored to provide a desired spectrum.
- a broad spectrum source is used for a color display when night vision goggles are unnecessary and a second source, which emits less longer wavelength light, is used when night vision goggles are required. This enables the display to satisfy the requirements of an observer wearing night vision goggles without degrading the color display that is used when night vision goggles are unnecessary.
- the present invention provides a display apparatus comprising a light transmissive display, means for directing light toward the light transmissive display, a first light source that has a first spectral output, and a second light source which has a second spectral output where the first and second spectral outputs are different.
- Figure 1 illustrates how the spectral output of a transmissive display was controlled in the past
- Figure 2 illustrates a transmissive display using multiple light sources with differing spectral outputs.
- FIG. 1 illustrates how the spectral output of transmissive displays was controlled in the past.
- Light produced by lamp 10 is used as a backlight for transmissive display 12.
- the light produced by lamp 10 is emitted in all directions. Since some of the light is emitted in a direction away from observer 16, reflector 18 directs light, such as light rays 20 and 22, through transmissive display 12 to observer 16.
- the spectrum of the light that passes through transmissive display 12 to observer 16 is controlled with optical filter 24.
- Optical filter 24 is used to remove the unwanted wavelengths emitted by lamp 10.
- optical filter 24 The longer wavelengths of light that interfere with night vision goggles are removed by optical filter 24, however, removing the longer wavelength light degrades the color display that is desired when night vision goggles are unnecessary.
- the present invention uses multiple light sources having differing spectral outputs to control the spectrum of light seen by an observer through a transmissive display.
- the spectrum seen by the observer is controlled by activating any one or combination of differing light sources to obtain a desired spectrum.
- FIG. 2 illustrates one embodiment of the present invention.
- Light sources 40 and 42 have differing spectral outputs. The light sources can be activated one at a time or simultaneously to provide a desired spectral output to an observer.
- Light source 40 is used to provide a broad spectrum of light that enhances a color display
- light source 42 is used to provide a spectrum that minimizes the longer wavelength light so that an observer wearing night vision goggles can use the display.
- the light emitted by sources 40 and 42 is emitted in all directions.
- Reflector 46 can be made in any convenient shape that facilitates a uniform illumination of transmissive display 48. It is even possible to use separate reflectors for light source 40 and 42. In some embodiments reflector 46 can be replaced by a light conduit, such as a light pipe or optical fiber, that directs the light toward observer 44. It is also possible to place a defiiser between the light sources and transmissive display 48.
- Transmissive display 48 can be a liquid crystal display, a plasma display, a display using dichroic liquid crystals or any other type of display that is transmissive.
- light sources 40 and 42 contain lamps 50 and 52 respectively. Lamps 50 and 52 can be incandescent or fluorescent.
- the spectral output of light sources 40 and 42 can be controlled by using lamps that have an envelope which comprises glass or other materials that filter out undesired wavelengths. The spectral output can also be controlled using a filter or sleeve that surrounds each lamp.
- Lamp 50 is surrounded by glass filter or sleeve 54.
- Glass filter 54 is used to remove or filter the undesired wavelengths emitted by lamp 50.
- Lamp 52 is surrounded by glass filter or sleeve 56.
- Glass filter 56 removes or filters the undesired wavelengths emitted by lamp 52.
- the glass that is used to construct sleeves 54 and 56 can be replaced with plastic or any other material that will filter out the undesired wavelengths.
- Lamps 50 and 52 can be replaced with light emitting diodes (LEDs) or electroluminescent devices, and if necessary, the spectral output of these devices can be filtered as discussed with respect to the lamps.
- LEDs light emitting diodes
- electroluminescent devices if necessary, the spectral output of these devices can be filtered as discussed with respect to the lamps.
- any combination of lamps, filters, LEDs or electroluminescent devices can be used to control the spectrum of light that passes through transmissive display 48. It is possible to use more than two light sources to increase the selection of spectral outputs associated with a particular display.
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- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Mathematical Physics (AREA)
- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
Abstract
The spectral output of a display is controlled by using a backlight having a plurality of light sources. Each light source provides a different spectral output. The display's spectral output is controlled by activating the light source or combination of light sources that provide the desired spectrum.
Description
TRANSMISSIVE DISPLAY HAVING A CONTROLLED SPECTRAL OUTPUT
Background of the Invention
Field of the Invention:
The present invention relates to transmissive displays, more specifically it relates to backlighting a transmissive display using a spectrally controlled light source.
Description of the Related Art:
Transmissive displays such as liquid crystal displays (LCDs) are used in a variety of applications. Some of these applications include military applications where two modes of operation are required. The first mode comprises providing a color display that enhances the observer's ability to comprehend information, and the second mode comprises a display that can be used while an observer is wearing night vision goggles. Displays suitable for observation through night vision goggles require suppressing the longer wavelengths of light that are produced by the display's backlight. In the past, an optical filter was placed between a full spectrum backlight and the transmissive display seen by the observer. This solution blocked the longer wavdengths and made it possible to produce a display that was compatible with night vision goggles, however, the missing wavelengths degraded the color display that was desired when night vision goggles were unnecessary.
Summary
The present invention provides a transmissive display that has a backlight that uses two or more spectral sources. Each spectral source is tailored to provide a desired spectrum. A broad spectrum source is used for a color display when night vision goggles are unnecessary and a second source,
which emits less longer wavelength light, is used when night vision goggles are required. This enables the display to satisfy the requirements of an observer wearing night vision goggles without degrading the color display that is used when night vision goggles are unnecessary.
The present invention provides a display apparatus comprising a light transmissive display, means for directing light toward the light transmissive display, a first light source that has a first spectral output, and a second light source which has a second spectral output where the first and second spectral outputs are different.
Brief Description of the Drawings Figure 1 illustrates how the spectral output of a transmissive display was controlled in the past; and
Figure 2 illustrates a transmissive display using multiple light sources with differing spectral outputs.
Detailed Description of the Invention Figure 1 illustrates how the spectral output of transmissive displays was controlled in the past. Light produced by lamp 10 is used as a backlight for transmissive display 12. The light produced by lamp 10 is emitted in all directions. Since some of the light is emitted in a direction away from observer 16, reflector 18 directs light, such as light rays 20 and 22, through transmissive display 12 to observer 16. The spectrum of the light that passes through transmissive display 12 to observer 16 is controlled with optical filter 24. Optical filter 24 is used to remove the unwanted wavelengths emitted by lamp 10.
The longer wavelengths of light that interfere with night vision goggles are removed by optical filter 24, however, removing the longer
wavelength light degrades the color display that is desired when night vision goggles are unnecessary.
The present invention uses multiple light sources having differing spectral outputs to control the spectrum of light seen by an observer through a transmissive display. The spectrum seen by the observer is controlled by activating any one or combination of differing light sources to obtain a desired spectrum.
Figure 2 illustrates one embodiment of the present invention. Light sources 40 and 42 have differing spectral outputs. The light sources can be activated one at a time or simultaneously to provide a desired spectral output to an observer. Light source 40 is used to provide a broad spectrum of light that enhances a color display, and light source 42 is used to provide a spectrum that minimizes the longer wavelength light so that an observer wearing night vision goggles can use the display. The light emitted by sources 40 and 42 is emitted in all directions.
The light that is emitted in a direction away from observer 44 is redirected toward the observer by reflector 46. Reflector 46 can be made in any convenient shape that facilitates a uniform illumination of transmissive display 48. It is even possible to use separate reflectors for light source 40 and 42. In some embodiments reflector 46 can be replaced by a light conduit, such as a light pipe or optical fiber, that directs the light toward observer 44. It is also possible to place a defiiser between the light sources and transmissive display 48.
Transmissive display 48 can be a liquid crystal display, a plasma display, a display using dichroic liquid crystals or any other type of display that is transmissive. light sources 40 and 42 contain lamps 50 and 52 respectively. Lamps 50 and 52 can be incandescent or fluorescent. The spectral output of light sources 40 and 42 can be controlled by using lamps that have an envelope
which comprises glass or other materials that filter out undesired wavelengths. The spectral output can also be controlled using a filter or sleeve that surrounds each lamp. Lamp 50 is surrounded by glass filter or sleeve 54. Glass filter 54 is used to remove or filter the undesired wavelengths emitted by lamp 50. Lamp 52 is surrounded by glass filter or sleeve 56. Glass filter 56 removes or filters the undesired wavelengths emitted by lamp 52. By proper selection of the glass filters, it is possible to tailor the spectral output of each lamp as desired. The glass that is used to construct sleeves 54 and 56 can be replaced with plastic or any other material that will filter out the undesired wavelengths. It is also possible to control the spectral output of the lamps by using lamps containing different gases or phosphors, or by using lamps with different coatings or films that filter the spectrum of light passing through the coating or film. Once the spectral output of each lamp is tailored as desired, the spectral output through transmissive display 48 can be controlled by turning on the lamp or combination of lamps that will produce the desired spectral output.
Lamps 50 and 52 can be replaced with light emitting diodes (LEDs) or electroluminescent devices, and if necessary, the spectral output of these devices can be filtered as discussed with respect to the lamps.
Any combination of lamps, filters, LEDs or electroluminescent devices can be used to control the spectrum of light that passes through transmissive display 48. It is possible to use more than two light sources to increase the selection of spectral outputs associated with a particular display.
Claims
1. A display apparatus, comprising:
(a) a light transmissive display; (b) means for directing light toward said light transmissive display;
(c) a first light source having a first spectral output; and
(d) a second light source having a second spectral output, said first spectral output and said second spectral output being different.
2. The display apparatus of claim 1, wherein said light sources comprise incandescent lamps.
3. The display apparatus of claim 1, wherein said light sources comprise fluorescent lamps.
4. The display apparatus of claim 1, wherein said first light source comprises a lamp having a third spectral output, said lamp being covered with a coating which filters said third spectral output to produce said first spectral output.
5. The display apparatus of claim 4, wherein said light sources comprise incandescent lamps.
6. The display apparatus of claim 4, wherein said light sources comprise fluorescent lamps.
7. The display apparatus of claim 1, wherein said first light sources comprises a first lamp containing a first phosphor and said second light source comprises a second lamp containing a second phosphor, said first phosphor and said second phosphor being different.
8. The display apparatus of claim 1, wherein said first light sources comprises an LED.
9. The display apparatus of claim 1, wherein said first light sources comprises an electroluminescent device.
10. A display apparatus, comprising:
(a) a light transmissive display;
(b) means for directing light toward said light transmissive display; (c) a first light source having a first spectral output, said first light source comprising a lamp surrounded by a sleeve that filters an undesired wavelength; and
(d) a second light source having a second spectral output, said first spectral output and said second spectral output being different.
11. The display apparatus of claim 10, wherein said light sources comprise incandescent lamps.
12. The display apparatus of claim 10, wherein said light sources comprise fluorescent lamps.
13. A display apparatus, comprising:
(a) a light transmissive display;
(b) means for directing light toward said light transmissive display; (c) a first light source having a first spectral output, said first light source having a lamp comprising an envelope that filters an undesired wavelength; and
(d) a second light source having a second spectral output, said first spectral output and said second spectral output being different.
14. The display apparatus of claim 13, wherein said lamp is incandescent.
15. The display apparatus of claim 13, wherein said lamp is fluorescent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90423292A | 1992-06-25 | 1992-06-25 | |
| US904,232 | 1992-06-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1994000794A1 true WO1994000794A1 (en) | 1994-01-06 |
Family
ID=25418814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1993/005987 Ceased WO1994000794A1 (en) | 1992-06-25 | 1993-06-22 | Transmissive display having a controlled spectral output |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO1994000794A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5709600A (en) * | 1996-03-27 | 1998-01-20 | Townsend Engineering Company | Method and means for linking and then separating encased sausage |
| FR2870359A1 (en) * | 2004-05-11 | 2005-11-18 | Thales Sa | METHOD FOR FILTERING LIGHTING SOURCES FOR NIGHT VISION |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061587A (en) * | 1979-09-10 | 1981-05-13 | Stolov M | Electronically controlled colour displays |
| GB2094051A (en) * | 1981-02-28 | 1982-09-08 | Thorn Emi Ltd | Display device |
| EP0342835A1 (en) * | 1988-05-18 | 1989-11-23 | Stc Plc | Liquid crystal cell addressing |
| EP0399173A2 (en) * | 1989-05-25 | 1990-11-28 | Stanley Electric Co., Ltd. | Color display device |
| DE3930513A1 (en) * | 1989-09-13 | 1991-04-11 | Grigull Karl August | Luminescent test screen - for artificial and daylight with PMMA plate for uniform light distribution |
| EP0454435A2 (en) * | 1990-04-24 | 1991-10-30 | Sharp Kabushiki Kaisha | Plain light source device |
-
1993
- 1993-06-22 WO PCT/US1993/005987 patent/WO1994000794A1/en not_active Ceased
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061587A (en) * | 1979-09-10 | 1981-05-13 | Stolov M | Electronically controlled colour displays |
| GB2094051A (en) * | 1981-02-28 | 1982-09-08 | Thorn Emi Ltd | Display device |
| EP0342835A1 (en) * | 1988-05-18 | 1989-11-23 | Stc Plc | Liquid crystal cell addressing |
| EP0399173A2 (en) * | 1989-05-25 | 1990-11-28 | Stanley Electric Co., Ltd. | Color display device |
| DE3930513A1 (en) * | 1989-09-13 | 1991-04-11 | Grigull Karl August | Luminescent test screen - for artificial and daylight with PMMA plate for uniform light distribution |
| EP0454435A2 (en) * | 1990-04-24 | 1991-10-30 | Sharp Kabushiki Kaisha | Plain light source device |
Non-Patent Citations (1)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN vol. 13, no. 89 (P-836)(3437) 2 March 1989 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5709600A (en) * | 1996-03-27 | 1998-01-20 | Townsend Engineering Company | Method and means for linking and then separating encased sausage |
| FR2870359A1 (en) * | 2004-05-11 | 2005-11-18 | Thales Sa | METHOD FOR FILTERING LIGHTING SOURCES FOR NIGHT VISION |
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