GB2291978A - Display system - Google Patents
Display system Download PDFInfo
- Publication number
- GB2291978A GB2291978A GB9418863A GB9418863A GB2291978A GB 2291978 A GB2291978 A GB 2291978A GB 9418863 A GB9418863 A GB 9418863A GB 9418863 A GB9418863 A GB 9418863A GB 2291978 A GB2291978 A GB 2291978A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light
- display system
- modulators
- spatial light
- spatial
- 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- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
- H04N5/7416—Projection arrangements for image reproduction, e.g. using eidophor involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
- H04N5/7458—Projection arrangements for image reproduction, e.g. using eidophor involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3102—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
- H04N9/3111—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources
- H04N9/3114—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources by using a sequential colour filter producing one colour at a time
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Projection Apparatus (AREA)
Abstract
A projection display system includes a light source 101 which produces light which is spatially modulated by a number of spatial light modulators 105, 107. A splitting means 103 is provided in the light path between the light source 101 and the spatial light modulators 105 and 107 such that the overall light flux produceable by the system is not determined by the maximum light flux which each spatial light modulator 105, 107 can accommodate. <IMAGE>
Description
DISPLAY SYSTEM
This invention relates to display systems. The invention has particular, although not exclusive, relevance to display systems including a projection system in which light from a light source is modulated by a spatial light modulator device, the modulated light then being projected onto a projection screen.
Spatial light modulator devices suitable for use in such projection systems may take several forms.
One example of a spatial light modulator device is a liquid crystal device comprising a matrix of individually addressable liquid crystal pixels. Such spatial light modulators may act either in a transmissive mode in which the light passes through the pixels of the liquid crystal device, or in a reflective mode in which the light is reflected by each pixel of the liquid crystal device.
Another example of a spatial light modulator device is a reflective light valve in the form of an array of mirrored cantilever beam structures, each structure carrying an electrode so as to be electrostatically deflectable between two positions. Thus dependent on the electric field applied to the device, each structure will reflect an incident light beam into two alternative light paths, either towards an optical system for a projection towards the projection screen or alternatively into a beam dump. Using an array of such structures, each structure being individually addressable by part of the incoming light beam, the incoming light beam can be spatially modulated with a two dimensional image which can then be projected onto the projection screen.
Known projection systems in which light from a light source is modulated by a spatial light modulator device suffer the disadvantage that there is often a limit in the amount of light flux which can be directed onto the spatial light modulator. This limit is caused by, for example limitations associated with the heating effect of the radiant flux, or saturation due to a high luminous flux. Where projection systems are limited in light output, two or more projection systems may be "stacked" by placing the projection systems adjacent to each other such that the projected images are superimposed on the projection screen, producing an overall bright image.
However, such an arrangement is both inefficient and space consuming.
In order to achieve a colour projection system it is known to split the incoming light by one or more spectral splitting devices, for example, dichroic mirrors into three primary colour channels. Such a prior art system is described for example in our international application
WO 94/10675. However such arrangements do not take account of the fact that the light flux of the various spectral components, for example the primary colours red, green and blue within white light, is unequal.
It is an object of the present invention to provide a display device in which the above problems of limited output light are at least alleviated.
According to a first aspect of the present invention there is provided a display system comprising: a light source; at least two spatial light modulators; means for splitting light of the same spectral composition from the light source between the spatial light modulators; means for combining spatially modulated light produced by the spatial light modulators; and means for displaying the combined light.
According to a second aspect of the present invention there is provided a display system comprising: a multi wave length light source; a plurality of spatial light modulators; wavelength selective means for splitting light of different spectral composition between the spatial light modulators; means for combining spatially modulated light produced by the spatial light modulators; and means for displaying the combined light; wherein there are provided sufficient spatial light modulators to increase the balance of the division of the light flux produced by the light source between the spatial light modulators.
The means for displaying suitably comprising a means for projecting the combined light onto a projection screen.
A number of embodiments of the invention will now be described by way of example only with reference to the accompanying figures in which:
Figure 1 is a schematic diagram of a display system in accordance with a first embodiment of the invention;
Figure 2 is a schematic diagram of a display system in accordance with a second embodiment of the invention; and
Figure 3 is a schematic diagram of a display system in accordance with a third embodiment of the invention.
Turning firstly to Figure 1, in the first embodiment of the display device in accordance with the invention, a light source 101 is arranged to direct light onto a half silvered mirror 103. The half silvered mirror 103 is effective to split the incident light between two spatial light modulators 105, 107 each in the form of a reflective light valve. Spatially modulated light from the modulators 105, 107 is recombined at the mirror 103, from which it passes through a projection lens 109 to be projected onto a projection screen 111.
It will be seen that by use of the half silvered splitter 103, the light which would in prior art arrangements have been incident on a single spatial light modulator is split between the two spatial light modulators 105, 107.
Thus the luminous flux incident on the projection screen 111 is twice that which would have been possible using a single spatial light modulator as in the prior art arrangements.
It will be appreciated that other forms of light splitters to a half silvered splitter may be used to split the incident light beam between the two spatial light modulators 105, 107. One possibility is the use of a polarized splitter in which P-polarized light is directed to one of the two spatial light modulators 105, 107 and S-polarized light is directed towards the other of the spatial light modulators. The polarized splitter then acts to recombine the spatially modulated light from the two spatial light modulators 105, 107 for transmission to the projector lens 109. It will be appreciated that a polarized splitter is more efficient than a half silvered splitter.
Referring now to Figure 2 this figure illustrates a multi colour projection system including four spatial light modulators 401, 403, 405 and 407 each in the form of a reflective light valve. Three dichroic mirrors 409, 411 and 413 are arranged in the light path of a white light source (not shown). The dichroic mirror 409 is arranged to reflect red light onto the spatial light modulator 401 and transmit all other light, whilst the dichroic mirror 411 is arranged to reflect blue light onto the spatial light modulator 403 and transmit the remaining green light. The third dichroic mirror 413 is designed to have a closely controlled band-pass characteristic so as to reflect part of the incident green light with a chosen spectral content onto the third spatial light modulator 405 and transmit the remaining green light onto the fourth spatial light modulator 407.
Each spatial light modulator 401, 403, 405 and 407 is driven by address signals to provide an appropriately spatially modulated image in one of the primary colours red and blue and the two spectral portions of green. The spatial light modulators 401, 403, 405 and 407 are arranged such that the reflected spatially modulated light is reflected back, and recombined by the various dichroic mirrors 409, 411, 413 to produce a multiwavelength spatially modulated lightbeam, which is then arranged to pass through a projection lens (not shown) and to be projected onto a projection screen (not shown).
It will be appreciated that where the spatial light modulators are in the form of a matrix of mirrored surfaces, then a handedness is provided at the reflection leading to the spatial modulation. This will be compensated for by the reflection at the appropriate reflective surfaces 409, 411 or 415. However in the arrangement shown in Figure 2 the return light path from the spatial light modulator 407 does not include a compensatory reflective surface. A reflector 415 as shown in dotted lines in Figure 2 can be added with the second "green" spatial light modulator 407 being disposed on the reflective path to and from the reflector 415 as indicated by 407'.
It will be appreciated that as in the first embodiment alternative splitters to the dichroic mirror 413 may be used. A particularly efficient way of splitting the green light is to introduce a polarized splitter such that separated P-polarized and S-polarized green light is incident on the two spatial light modulators 405 and 407. Alternatively a half-silvered mirror may be used.
It will be appreciated that in the example given before, as white light generally contains more green light than red or blue light, there are two green spatial light modulators. However in some circumstances it may be appropriate to have some other combinations of light modulators which are effective to share the total light flux in convenient proportions amongst the spatial light modulators. For example as white light typically comprises 30% red light, 60% green light and 10% blue light, the number of spatial light modulators sharing the total light flux in each colour channel can be set according to the light flux in each channel. Such an arrangement can be used to improve colour fidelity as well as enhancing light output from the same light input.
It will be appreciated that whilst the second embodiment is described in relation to the splitting of the input light into the primary colours red, blue and green, the invention is equally applicable to the splitting of the input light into the secondary colours yellow, magenta and cyan, or any other colour splitting scheme.
It will be seen that in the embodiment of the invention described in relation to Figure 2, the input light is split into three different colour components such that the three components are spatially modulated simultaneously. However, in a display system in accordance with the invention, light of different colours may be passed sequentially through the display system.
Such an arrangement is shown in Figure 3 in which light from a light source comprising an arc lamp 501 and a condenser lens 503 is arranged to pass sequentially through portions of a colour wheel 505. The wheel 505 is rotatable by a motor 507 about a central axis so as to superimpose in sequence, red, blue and green filters in the light path from the light source 501, 503. As in the first embodiment described in relation to Figure 1, a polarizing beam splitter 509 is placed in the light path, the polarizing beam splitter being effective to divide the incident light into P-polarized and Spolarized light components. The P-polarized light is directed towards a first spatial light modulator 511, whilst the S-polarized light is directed towards a second spatial light modulator 513. Spatially modulated light from the spatial light modulators 511, 513 passes back to the beam splitter 509, which re-combines the S and Ppolarized light and directs it towards a projection lens 515 for projection onto a projection screen (not shown).
The speed of rotation of the colour wheel 505 is chosen such that the time for light of all three different colour components to pass through the display system and be projected on the projection screen, is short enough such that the eyes of an observer watching the projection screen integrate the three different coloured projected images on the display screen, and a full colour image is seen by the observer.
It will be appreciated that as in the other embodiments described herebefore, whilst the use of a polarized splitter is particularly advantageous, other forms of splitter may be used.
Claims (13)
1. A display system comprising:
a light source;
at least two spatial light modulators;
means for splitting light of the same spectral composition from the light source between the spatial light modulators;
means for combining spatially modulated light produced by the spatial light modulators; and
means for displaying the combined light.
2. A display system comprising:
a multi wavelength light source;
a plurality of spatial light modulators;
wavelength selective means for splitting light of different spectral composition between the spatial light modulators;
means for combining spatially modulated light produced by the spatial light modulators; and
means for displaying the combined light;
wherein there are provided sufficient spatial light modulators to increase the balance of the division of the light flux produced by the light source between the spatial light modulators.
3. A display system according to either of the preceding claims wherein said means for displaying comprises:
a means for projecting the combined light onto a projection screen.
4. A display system according to any one of the preceding claims wherein each spatial light modulator is a deflectable mirror array.
5. A display system according to any one of the preceding claims wherein each spatial light modulator is effective to reflect spatially modulated light, and wherein said means for splitting light additionally combines the spatially modulated light reflected by the spatial light modulators.
6. A display system according to any one of the preceding claims wherein said means for splitting light comprises at least one polarized splitter effective to split the light incident thereon into P-polarized light and S-polarized light components.
7. A display system according to any one of the preceding claims wherein said means for splitting light comprises:
at least one semi-reflective means which is effective to reflect part of the light incident thereon and to transmit the rest of the light incident thereon.
8. A display system according to any one of the preceding claims wherein said means for splitting light comprises a dichroic means.
9. A display system according to claim 8 wherein the dichroic means splits light within same primary colour band.
10. A display system according to claim 9 in which there are provided at least two spatial light modulators in respect of two wavelength bands in the green light spectrum.
11. A display system according to any one of the preceding claims wherein each spatial light modulator is effective to reflect spatially modulated light, and in which the number of reflective means provided in the light path causes the spatially modulated combined light to undergo compensatory reflections to correct for any handedness imported by the spatial light modulators on the spatially modulated light.
12. A display system according to claim 1 and any one of claims 3 to 11 when dependent on claim 1, including means for sequentially directing light of different spectral compositions through the display system.
13. A display system substantially as hereinbefore described with reference to Figures 1, 2 and 3 of the accompanying drawings.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE69535346T DE69535346T2 (en) | 1994-08-04 | 1995-08-02 | DISPLAY DEVICE |
| EP95927839A EP0774130B1 (en) | 1994-08-04 | 1995-08-02 | Display system |
| PCT/GB1995/001842 WO1996004582A1 (en) | 1994-08-04 | 1995-08-02 | Display system |
| JP50633396A JP4006478B2 (en) | 1994-08-04 | 1995-08-02 | Display system |
| US08/776,805 US6276801B1 (en) | 1994-08-04 | 1995-08-02 | Display system |
| AT95927839T ATE349024T1 (en) | 1994-08-04 | 1995-08-02 | DISPLAY DEVICE |
| US09/918,818 US6631993B2 (en) | 1994-08-04 | 2001-07-30 | Display system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9415771A GB9415771D0 (en) | 1994-08-04 | 1994-08-04 | Display system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9418863D0 GB9418863D0 (en) | 1994-11-09 |
| GB2291978A true GB2291978A (en) | 1996-02-07 |
Family
ID=10759397
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9415771A Pending GB9415771D0 (en) | 1994-08-04 | 1994-08-04 | Display system |
| GB9418863A Withdrawn GB2291978A (en) | 1994-08-04 | 1994-09-19 | Display system |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9415771A Pending GB9415771D0 (en) | 1994-08-04 | 1994-08-04 | Display system |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9415771D0 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8085462B2 (en) | 2003-12-29 | 2011-12-27 | Max Mayer | Superposition method using a pair of stereo-isomeric micro electro mechanical systems (MEMSs) |
| WO2014012665A2 (en) | 2012-07-18 | 2014-01-23 | Binsight3D Gmbh | Image engine and projection system with two discrete format channels |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3495892A (en) * | 1966-01-21 | 1970-02-17 | Rca Corp | Split beam light modulator |
| US3609381A (en) * | 1968-07-31 | 1971-09-28 | Technical Operations Inc | Electrooptic light modulator with birefringent beamsplitter-recombiner |
| GB1363885A (en) * | 1970-08-17 | 1974-08-21 | Westinghouse Electric Corp | Light beam polarization modulator |
| GB2046937A (en) * | 1979-04-09 | 1980-11-19 | Crosfield Electronics Ltd | Optical intensity modulators |
| US4864390A (en) * | 1986-08-22 | 1989-09-05 | North American Philips Corporation | Display system with equal path lengths |
| US5035475A (en) * | 1990-03-15 | 1991-07-30 | Aura Systems, Inc. | Unique modulation television |
| US5105299A (en) * | 1990-12-31 | 1992-04-14 | Texas Instruments Incorporated | Unfolded optics for multiple row deformable mirror device |
| GB2252173A (en) * | 1991-01-25 | 1992-07-29 | Rank Brimar Ltd | Colour optical output system |
| GB2252172A (en) * | 1991-01-25 | 1992-07-29 | Rank Brimar Ltd | Colour optical output system |
-
1994
- 1994-08-04 GB GB9415771A patent/GB9415771D0/en active Pending
- 1994-09-19 GB GB9418863A patent/GB2291978A/en not_active Withdrawn
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3495892A (en) * | 1966-01-21 | 1970-02-17 | Rca Corp | Split beam light modulator |
| US3609381A (en) * | 1968-07-31 | 1971-09-28 | Technical Operations Inc | Electrooptic light modulator with birefringent beamsplitter-recombiner |
| GB1363885A (en) * | 1970-08-17 | 1974-08-21 | Westinghouse Electric Corp | Light beam polarization modulator |
| GB1368598A (en) * | 1970-08-17 | 1974-10-02 | Westinghouse Electric Corp | Light beam polarization modulator |
| GB2046937A (en) * | 1979-04-09 | 1980-11-19 | Crosfield Electronics Ltd | Optical intensity modulators |
| US4864390A (en) * | 1986-08-22 | 1989-09-05 | North American Philips Corporation | Display system with equal path lengths |
| US4864390B1 (en) * | 1986-08-22 | 1990-12-11 | Philips Corp | |
| US5035475A (en) * | 1990-03-15 | 1991-07-30 | Aura Systems, Inc. | Unique modulation television |
| US5105299A (en) * | 1990-12-31 | 1992-04-14 | Texas Instruments Incorporated | Unfolded optics for multiple row deformable mirror device |
| GB2252173A (en) * | 1991-01-25 | 1992-07-29 | Rank Brimar Ltd | Colour optical output system |
| GB2252172A (en) * | 1991-01-25 | 1992-07-29 | Rank Brimar Ltd | Colour optical output system |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8085462B2 (en) | 2003-12-29 | 2011-12-27 | Max Mayer | Superposition method using a pair of stereo-isomeric micro electro mechanical systems (MEMSs) |
| WO2014012665A2 (en) | 2012-07-18 | 2014-01-23 | Binsight3D Gmbh | Image engine and projection system with two discrete format channels |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9418863D0 (en) | 1994-11-09 |
| GB9415771D0 (en) | 1994-09-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |