GB2209422A - Displays - Google Patents

Displays Download PDF

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Publication number
GB2209422A
GB2209422A GB8720735A GB8720735A GB2209422A GB 2209422 A GB2209422 A GB 2209422A GB 8720735 A GB8720735 A GB 8720735A GB 8720735 A GB8720735 A GB 8720735A GB 2209422 A GB2209422 A GB 2209422A
Authority
GB
United Kingdom
Prior art keywords
electro
display device
optic display
screen
optical devices
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.)
Granted
Application number
GB8720735A
Other versions
GB8720735D0 (en
GB2209422B (en
Inventor
Mark Dempster
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.)
Thorn EMI PLC
Original Assignee
Thorn EMI PLC
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 Thorn EMI PLC filed Critical Thorn EMI PLC
Priority to GB8720735A priority Critical patent/GB2209422B/en
Publication of GB8720735D0 publication Critical patent/GB8720735D0/en
Publication of GB2209422A publication Critical patent/GB2209422A/en
Application granted granted Critical
Publication of GB2209422B publication Critical patent/GB2209422B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • G09F13/0409—Arrangements for homogeneous illumination of the display surface, e.g. using a layer having a non-uniform transparency
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
    • G02B27/102—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources
    • G02B27/1046—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources for use with transmissive spatial light modulators
    • G02B27/1053—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources for use with transmissive spatial light modulators having a single light modulator for all colour channels
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/14—Beam splitting or combining systems operating by reflection only
    • G02B27/144—Beam splitting or combining systems operating by reflection only using partially transparent surfaces without spectral selectivity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/14—Beam splitting or combining systems operating by reflection only
    • G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
    • 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
    • G02F1/133605—Direct backlight including specially adapted reflectors
    • 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
    • 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
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/09—Function characteristic transflective

Abstract

An electro-optic display device comprises a display screen and e.g. an LCD panel, back-lit by reflected light from an arrangement comprising a set 11-16; 17-22, of partially-reflective, partially-transmissive optical devices positioned in a line-of-sight arrangement with one another and elements 5, 6 or 7, 8 or 9 producing a beam of light which is incident on one of the devices 11 or 17. The devices 11-16; 17-22 may be flat or parabolic mirrors having different reflectivity characteristics to derive uniform light intensity from each mirror. A colour filter 23 may be provided between the mirrors and the panel 4 and a matt black screen 10 cuts off direct light from source 5. Instead of the two sets of mirrors 11-16; 17-22 shown, a single set, a number of single sets or a number of two sets of mirrors may be provided. <IMAGE>

Description

DISPLAYS The present invention relates to a display, especially but not solely a liquid crystal display, which incorporates collimated back lighting.
Liquid crystal displays have a limited viewing angle and low contrast. Such characteristics are particularly disadvantageous when attempting to produce a large area (i.e. a high number of pixels) display panel capable of displaying a complex image rather than, for example, an image of one or a few digits. To overcome the above limitations it is usually necessary to back-illuminate the display with collimated light and employ a diffusing front screen to scatter the light over large viewing angles. This also improves contrast since all light now passes normally through the liquid crystal material.
The present invention provides an electro-optic display device having means to effect collimated back-lighting for a display screen, the back-lighting means comprising a set of partially-reflective, partially-transmissive optical devices positioned in a line-of-sight arrangement with one another and located to reflect light towards the screen, and means to produce a beam of light incident on one of the optical devices in the direction of the said line.
In this way, a liquid crystal display can be provided with effective, uniform back-lighting.
Preferably, the optical devices in a set have different reflectivity characteristics, advantageously the devices being arranged according to the associated reflectivity characteristics such that there is a constant light intensity reflected at each optical device.
Prefer ably, an optical device comprises a planar surface on which the light beam is incident; for example, an optical device may comprise a part-silvered flat mirror. Alternatively an optical device may comprise a parabolic surface on which the light beam is incident.
Prefer ably, the optical devices in a set are inclined at substantially the same angle, advantageously 450, to the screen. Alternatively, the optical devices may be inclined at different angles to the screen, optionally with the spacing between adjacent devices varying along the line.
Preferably an optical device has a bevelled edge adjacent and parallel to the plane of the screen, to provide substantially continuous illumination of the screen.
Preferably the bevelled edge has an interior angle of substantially (90-çt), whereis the angle at which an optical device is inclined with respect to the screen.
Preferably, the light production means comprises a point light source, for example a tungsten/halogen lamp.
In order that the invention may more readily be understood, a description is now given, by way of example only, reference being made to the accompanying drawings, in which: Figure 1 is a schematic side view of part of a display embodying the present invention; Figure 2 shows the reflectivity characteristics of some of the mirrors in the display of Figure 1; and Figure 3 is a detail of the mirrors of the display of Figure 1.
Liquid crystal display 1, shown in Figure 1, has a diffusing screen 2 at the front of a housing 3 which contains a panel 4 formed of selectively settable liquid crystal cells each representing a pixel of the display. Details of the panel 4 itself are not shown or described because they are not pertinent to the present invention.
Panel 4 is illuminated from behind uniformly and continuously over its area. In order to achieve this, a point source tungsten/halogen lamp 5 is located intermediate, and at the focal planes of, two elongate aspheric Fresnel lens 6 and 7 which cause a parallel light beam to fall onto the right-angled pairs of mirrors 8 and 9 respectively. A matt black screen 10 shields panel 4 from receiving light directly from lamp 5.
The pair of mirrors 8 directs a beam of light onto a part-silvered mirror 11 which is inclined at 450 to the panel 4, such that a proportion of the incident beam is reflected onto the back of panel 4, while the remainder (ignoring any absorption losses) is transmitted through mirror 11 and is incident on the next mirror 12. Again, some of the light incident on mirror 12 is reflected towards the back of panel 4 while the remainder passes through towards mirror 13, this procedure being repeated at mirrors 14 and 15, mirror 16 is fully-silvered such that all the light incident on it is reflected towards panel 4.
As shown in Figure 2, mirrors 11 to 16 have different reflectivity characteristics, the specific values being chosen in order that the intensity of the light beam reflected towards the panel 4 by each mirror is constant, being 0.167 11 where I1 is the intensity of the light beam incident on mirror 11.
Likewise, a set of mirrors 17 to 22 are provided, with reflectivity characteristics the same as mirrors 11 to 16 respectively, in order to produce six light beams, each of intensity 0.167 I2 incident on the back panel 4, where 12 is the intensity of light directed onto mirror 17. As fl I1 is effectively the same as 12, uniform and constant illumination of panel 4 is provided.
A colour filter 23 may be provided intermediate the mirrors 11 to 22 and panel 4.
Each of the mirrors 11 to 22 has a bevelled edge 24 set at 450 on a lateral face adjacent and parallel to the panel 4, in order to eliminate any discontinuity in the illumination of panel 4. Such bevelling may be achieved by appropriate polishing, and minimises or prevents the gap G between mirrors arising from their finite width, typically about lmm. The internal angle of the bevel may be reduced to a value below 450 in order to further improve this effect. Alternatively, plastic particle membranes, less than 100 m thick, may be used to reduce this gap.
Each of the mirrors 11 to 22 has an anti-reflection coating 25 on its reverse face in order to minimise losses.
Display 1 can be modified by replacing lamp 5 and lenses 6, 7 with a light source of elongate form (for example a tubular fluorescent or incandescent lamp, or a number of point sources in a line) and appropriate lenses. In another modification, a display has only a single set of inclined mirrors (e.g.
corresponding to mirrors 11 to 16), as distinct from display 1 which has two sets of mirrors (namely 11 to 16 and 17 to 22).
In another modification, a display has a number of single sets of mirrors, or has a number of two sets of mirrors, or has a combination of single sets and two sets.
The above-described arrangement provides a liquid crystal display which is uniformly backlit, yet is thin (typically 10cm thick) as compared to conventional constructions. Moreover the display can be cheaply constructed, enables colour filters to be positioned outside the liquid crystal cell and utilizes a single light source thereby obviating problems of matching luminosities.

Claims (15)

1. An electro-optic display device having means to effect collimated back-lighting for a display screen, the back hating means comprising a set of partially-reflective, partiallytransmissive optical devices positioned in a line-of-sight arrangement with one another and located to reflect light towards the screen, and means to produce a beam of light incident on one.of the optical devices in the direction of the said line.
2. An electro-optic display device according to Claim 1 wherein the optical devices in a set have different reflectivity characteristics.
3. An electro-optic display device according to Claim 2 wherein the optical devices are arranged according to the associated reflectivity characteristics such that there is a constant light intensity reflects at each optical device.
4. An electro-optic display device according to any one of the preceding claims wherein an optical device comprises a planar surface on which the light beam is incident.
5. An electro-optic display device according to Claim 4 wherein an optical device comprises a part-silvered flat mirror.
6. An electro-optic display device according to any one of Claims 1 to 3 wherein an optical device comprises a parabolic surface on which the light beam is incident.
7. An electro-optic display device according to any one of the preceding claims wherein the optical devices in a set are inclined at substantially the same angle to the screen.
8. An electro-optic display device according to Claim 7 wherein said same angle is 450.
9. An electro-optic display device according to any one of Claims 1 to 6 wherein the optical devices in a set are inclined.
at different angles to the screen.
10. An electro-optic display device according to Claim 9 wherein the spacing between adjacent optical devices varies along the said line.
11. An electro-optic display device according to any one of the preceding claims wherein an optical device has a bevelled edge adjacent and parallel to the plane of the screen.
12. An electro-optic display device according to Claim 11 wherein the bevelled edge has an interior angle of substantially (90- oc),where ffi is the angle at which an optical device is inclined with respect to the screen.
13. An electro-optic display device according to any one of the preceding claims wherein the light production means comprises a point light source.
14. An electro-optic display device according to Claim 13 wherein the point light source comprises a tungsten/halogen lamp.
15. An electro-optic display device substantially as hereinbefore described with respect to any one of the Figures in the accompanying drawings.
GB8720735A 1987-09-03 1987-09-03 Displays Expired - Lifetime GB2209422B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8720735A GB2209422B (en) 1987-09-03 1987-09-03 Displays

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8720735A GB2209422B (en) 1987-09-03 1987-09-03 Displays

Publications (3)

Publication Number Publication Date
GB8720735D0 GB8720735D0 (en) 1987-10-07
GB2209422A true GB2209422A (en) 1989-05-10
GB2209422B GB2209422B (en) 1991-05-29

Family

ID=10623213

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8720735A Expired - Lifetime GB2209422B (en) 1987-09-03 1987-09-03 Displays

Country Status (1)

Country Link
GB (1) GB2209422B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0342292A2 (en) * 1988-05-16 1989-11-23 Think Laboratory Co., Ltd. An optical beam splitter
EP0588509A2 (en) * 1992-09-18 1994-03-23 Fujitsu Limited Stereoscopic display apparatus
GB2324364A (en) * 1997-04-19 1998-10-21 Ford Motor Co Light input device for a light pipe illuminator
EP1387162A1 (en) * 2002-07-31 2004-02-04 Tecan Trading AG Device and method for measuring the fluorescence life time of fluorophores in samples
NL1030161C2 (en) * 2005-10-11 2007-04-12 Matthijs Dirk Meulenbelt Presentation device.
WO2015039873A1 (en) * 2013-09-17 2015-03-26 Koninklijke Philips N.V. A lighting device
CN107422536A (en) * 2017-09-12 2017-12-01 青岛海信电器股份有限公司 A kind of down straight aphototropism mode set and display device
CN108931868A (en) * 2017-05-22 2018-12-04 船井电机株式会社 Liquid crystal display device and light supply apparatus

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987006995A1 (en) * 1986-05-16 1987-11-19 Bernhard Bartel Lamp

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987006995A1 (en) * 1986-05-16 1987-11-19 Bernhard Bartel Lamp

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0342292A2 (en) * 1988-05-16 1989-11-23 Think Laboratory Co., Ltd. An optical beam splitter
EP0342292A3 (en) * 1988-05-16 1991-02-06 Think Laboratory Co., Ltd. An optical beam splitter
EP0588509A2 (en) * 1992-09-18 1994-03-23 Fujitsu Limited Stereoscopic display apparatus
EP0588509A3 (en) * 1992-09-18 1996-05-29 Fujitsu Ltd Stereoscopic display apparatus
US5594559A (en) * 1992-09-18 1997-01-14 Fujitsu Limited Stereoscopic display apparatus
GB2324364A (en) * 1997-04-19 1998-10-21 Ford Motor Co Light input device for a light pipe illuminator
EP1387162A1 (en) * 2002-07-31 2004-02-04 Tecan Trading AG Device and method for measuring the fluorescence life time of fluorophores in samples
US7841733B2 (en) 2005-10-11 2010-11-30 Koninklijke Philips Electronics N.V. Display device
WO2007043886A1 (en) * 2005-10-11 2007-04-19 Koninklijke Philips Electronics N.V. Display device
CN101300616B (en) * 2005-10-11 2010-05-19 皇家飞利浦电子股份有限公司 Display device
NL1030161C2 (en) * 2005-10-11 2007-04-12 Matthijs Dirk Meulenbelt Presentation device.
WO2015039873A1 (en) * 2013-09-17 2015-03-26 Koninklijke Philips N.V. A lighting device
CN105706156A (en) * 2013-09-17 2016-06-22 飞利浦灯具控股公司 A lighting device
JP6000500B1 (en) * 2013-09-17 2016-09-28 フィリップス ライティング ホールディング ビー ヴィ Lighting device
JP2016537661A (en) * 2013-09-17 2016-12-01 フィリップス ライティング ホールディング ビー ヴィ Lighting device
US9588713B2 (en) 2013-09-17 2017-03-07 Philips Lighting Holding B.V. Lighting device
EP3033745B1 (en) 2013-09-17 2017-05-31 Philips Lighting Holding B.V. A lighting device
CN105706156B (en) * 2013-09-17 2018-01-26 飞利浦灯具控股公司 Lighting apparatus
CN108931868A (en) * 2017-05-22 2018-12-04 船井电机株式会社 Liquid crystal display device and light supply apparatus
CN107422536A (en) * 2017-09-12 2017-12-01 青岛海信电器股份有限公司 A kind of down straight aphototropism mode set and display device

Also Published As

Publication number Publication date
GB8720735D0 (en) 1987-10-07
GB2209422B (en) 1991-05-29

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930903