WO2006054253A1 - Color drum filter for projection system including light-absorbing baffles - Google Patents
Color drum filter for projection system including light-absorbing baffles Download PDFInfo
- Publication number
- WO2006054253A1 WO2006054253A1 PCT/IB2005/053788 IB2005053788W WO2006054253A1 WO 2006054253 A1 WO2006054253 A1 WO 2006054253A1 IB 2005053788 W IB2005053788 W IB 2005053788W WO 2006054253 A1 WO2006054253 A1 WO 2006054253A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- color
- light
- drum
- filter
- projection system
- Prior art date
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Classifications
-
- 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
-
- 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
- G02B26/007—Optical devices or arrangements for the control of light using movable or deformable optical elements the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light
- G02B26/008—Optical devices or arrangements for the control of light using movable or deformable optical elements the movable or deformable optical element controlling the colour, i.e. a spectral characteristic, of the light in the form of devices for effecting sequential colour changes, e.g. colour wheels
-
- 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
- H04N9/3117—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 two or more colours simultaneously, e.g. by creating scrolling colour bands
Definitions
- Color display projectors or projection televisions may be designed as three -primary color systems such as an RGB system (for example, red, green and blue), or as multi-primary color systems having more than three primary colors, such as an RGBYC system (red, green, blue, yellow and cyan).
- RGB system for example, red, green and blue
- RGBYC system red, green, blue, yellow and cyan
- the image carrying panel is illuminated or scrolled by the different colors sequentially in time.
- the scrolling colors can be generated by projecting white light from a source through a color wheel, a rotating prism or a color drum.
- the light source in a color projection system is a white light source comprising light components having wavelengths across the visible spectrum.
- the light source may be an ultra-high pressure (UHP) gas light, which emits white light.
- UHP ultra-high pressure
- Discontinuities between the color filters of the drum can result in unfiltered light from the light source being transmitted to the light- valve.
- the optical elements that are used to provide light from the light source to the color drum, as well as the color filters themselves may cause stray light (e.g., scattered light) to be incident on the light-valve and be projected onto the imaging surface (screen) of the display.
- this stray light may result in picture elements (pixels) at the light valve being illuminated by the wrong color, or the stray light's being imaged onto the screen at an improper location, or both. These and other affects can degrade the image quality. Moreover, as the number of pixels increases for increased resolution, the affects of stray light can be more pronounced.
- a color drum includes a plurality of color filters and at least one baffle.
- the baffle substantially absorbs light over a visible spectrum of wavelengths.
- a light- valve projection system includes a source of light, which includes a plurality of wavelength components.
- valve projection system also includes a color-drum, which includes a plurality of color filters.
- the color drum also includes at least one baffle, and the baffle substantially absorbs light over a visible spectrum of wavelengths.
- Fig. 1 is a perspective view of a color projection system in accordance with an example embodiment.
- Figs. 2a-2c are cross-sectional views of a color drum having color filters, shields and baffles in accordance with an example embodiment.
- Fig. 3 is a perspective view of a color drum in accordance with an example embodiment.
- Fig. 1 is a perspective view of a color projection system 100 in accordance with an example embodiment. It is emphasized that many of the components of the system 100 are known to one skilled in the art. These known components may not be described in significant detail, so as to avoid obscuring the description of the illustrative embodiments.
- the system 100 includes a light source 101, which is a source of white light.
- the light source may be a UHP gas lamp or similar device.
- the light source 101 includes a parabolic reflector such as shown.
- the light emitted by the source 101 traverses a polarization conversion system (PCS) 102, which transforms light incident thereon from the light source US040457
- PCS polarization conversion system
- the light emerges from the PCS 102 into a substantially linearly polarized state (e.g., S or P polarized light).
- a substantially linearly polarized state e.g., S or P polarized light
- the light that is emitted from the PCS 102 is incident on a condenser lens 102, and traverses other known lens elements 103, 104, 105. Ultimately, the light is coupled from a lens 106 to the color drum 107.
- the color drum 107 is rotating about an axis through a rod lens 108, which may be an element of the color drum 107.
- Light incident on the color drum 107 is selectively transmitted by the color drum 107, through optical elements 109, 110 and 111, and is incident on a polarization beam splitter (PBS) 112.
- the PBS 112 separates the light into its orthogonal polarization components, and transmits light of one polarization state to a light valve 113.
- light-valve 113 may be a liquid crystal (LC) panel, such as a liquid crystal on silicon (LCOS) panel.
- LCOS liquid crystal on silicon
- DLPTM digital light processing
- white light is emitted from the light source 101 and is incident on the color drum 107.
- the color drum rotates and provides a sequential scrolling of the colors of the color filters onto the light valve 112.
- a color image is provided at a display surface (not shown) through the scrolling of light across the light valve.
- the color drum 107 may be disposed in a pupil location. In such an embodiment, the color drum 107 is adapted for use in a color sequential mode, but without scrolling.
- the color drum 107 includes a plurality of color filters, namely twice as many as the desired number of primary colors desirably projected onto the light valve 112. For example, if the desired colors to be scrolled onto the light valve 112 and thus the display surface (not shown) are R, G, B there are six color filters, two for each primary color. Likewise, if a greater degree of color quality is desired and the system includes five colors (e.g., R, G, B, C, Y) that are scrolled, there are 10 color filter; again two for each color.
- White light from the source 101 may be outside the optimal cone of light, and/or may US040457
- the stray light may be incident on a color filter of the color drum 107 at a relatively high angle of incidence, and thus outside the tolerance angle of the color filter upon which the light is incident.
- the white light may be filtered but the light emerging from the color filter may not be of the intended color. Naturally, this may result in poor image quality.
- light that enters the color drum 107 may be reflected from the interior surfaces of the drum. After the reflections within the drum, the light may traverse the wrong color filter, or maybe incident at a relatively high angle of incidence on the filter or on the pixel of the light- valve, or both.
- the stray light is incident on the wrong color filter, the light may be transmitted on a pixel of the light- valve, and thus provide the wrong color to the pixel. If the stray light is incident at a high angle of incidence, the wrong color may be emitted. Also, further reflections of light within the drum may occur, further exacerbating the problem.
- stray light may be incident on the light- valve 112 at a relatively high angle of incidence. If this light is incident at a high angle of incidence on the light-valve, the light may be transmitted incorrectly onto the screen via the projection optics (not shown) of the display system 100. Beneficially, the example embodiments significantly reduce, if not substantially eliminate the affects of stray light.
- Fig. 2a is a cross- sectional view of a color drum 200 in accordance with an example embodiment.
- the color drum 200 is substantially a ten-sided structure.
- the color drum 200 includes a rod lens 211 disposed substantially concentrically about the center of the drum 200.
- the drum 200 is useful for a five color system.
- this is merely illustrative, and it is contemplated that more or fewer colors may be transmitted by the color drum in a scrolling projection application.
- the color drum 200 may include any number of different color segments; such as three color segments for use in a US040457
- RGB three-color
- the color drum 200 includes a plurality of color filters 201-210.
- the color filters are chosen and arranged for a five-color projection system (RGBYC) with a color filter for each color being disposed substantially directly opposite to a substantially identical color filter.
- color filter 204 may be a red color filter and is disposed directly opposite color filter 209, which is substantially identical to color filter 204.
- the relative size of the corresponding color filters may be made comparatively larger.
- the corresponding color filters may be comparatively smaller.
- the arrangement of the color drum described in connection with Fig. 2a is merely illustrative.
- a transmissive element that is not a color filter disposed substantially opposite at least one, if not each of the color filters, which substantially transmit one of the chosen primary colors.
- a glass element may be substituted for red color filter 209.
- the transparent elements may have an anti- reflective (AR) property (e.g., via an AR coating) to reduce reflections.
- one or more of color filters disposed directly opposite to a color filter may have wavelength transmission characteristics that are spectrally shifted relative to the characteristics of its counterpart.
- color filter 209 may have transmission characteristics (and thus, reflection or absorption characteristics) that are shifted spectrally relative to those of color filter 204.
- the out-of-band blocking characteristics of one or more color filters disposed directly opposite may be different from its counterpart.
- the color filter 209 may have out-of-band blocking characteristics that are different from those of color filter 204. These characteristics may make such a filter more favorable for various reasons.
- the above variations are merely illustrative and other variations will be US040457
- the color filters and transmissive or AR elements (if applicable) 201-210 are individual elements.
- gaps e.g., gaps 226 shown in Fig. 2c
- the light that passes through these gaps may not traverse a color filter.
- light may traverse the lens 105 and be incident on a gap between two color filters (e.g., filters 203 and 204) of the drum 200 and enter the drum as unfiltered light, which is substantially white light.
- this light may be incident on another gap, and emerge from the color drum 200 substantially unfiltered.
- light from the light source 101 may be transmitted to the light- valve unfiltered, and ultimately may have a deleterious impact on the quality of the image projected onto the screen.
- shields 211 are disposed between one or more of the filters 201-210. It is noted that the shields 211 may be disposed in the gaps, in front on the gaps (i.e., outside the color drum 200), or behind the gaps (i.e., inside the color drum). Shields 211 in front of and behind the gap 226 are shown between filter 202 and filter 203.
- the shields 211 comprise a material that is optically absorptive over the visible spectrum. Illustratively, a black or red silicon glue material may be used. Alternatively, black aluminum stripes may be used.
- the shields 211 prevent the transmission of unfiltered light from the light source to the light- valve.
- color filters/ AR elements 201-210 are substantially flat.
- the color filters, or AR elements, or both may be curved, providing a substantially cylindrical color drum. While the gaps between the color filters and AR elements may be reduced in such an embodiment, they will likely remain. As such, the shields 211 may be disposed to fill these gaps in order to reduce the stray light through the gaps.
- the shapes of the color drum 200 may be other than those described thus far.
- the color drum may be of a variety of other regular and irregular shapes and number of sides depending on the number of primary colors being transmitted to the light valve.
- the color filters are dichroic filters or multi-layer dielectric stack filters.
- at least one of the color filters may be another type of filter that transmits certain wavelengths and reflects undesired wavelengths.
- the color filters substantially absorb the light of all wavelengths except the wavelength(s) or wavelength band desirably transmitted. It is useful to include a cooling feature (e.g., a fan) to mitigate the thermal effects associated with absorptive filters.
- filters 201- 210 may be dichroic filters or multi-layer filters.
- dichroic filters or multi ⁇ layer dielectric stack filters transmit light of a particular wavelength or wavelength range that is incident at nearly normal incidence (approximately a 0° angle of incidence) to the surface of the filter. These filters normally have an angular tolerance so that light of the wavelength/wavelength range that is incident within the tolerance is transmitted.
- the blue filter may (undesirably) reflect the blue light and (again undesirably) transmit light of other wavelengths (colors).
- some of the light that is incident on the distal portion of the drum may be reflected back into the drum, where it undergoes a number of further reflections and then is transmitted through the distal side.
- the light of the wrong color may be transmitted through the distal side of the drum. In either event, light of the wrong color may be incident on the pixels of the light- valve. This will ultimately impact the quality of the image provided at the screen.
- the stray light that is reflected within the within the drum is significantly reduced, if not substantially eliminated, by a plurality of US040457
- baffles 212 that are disposed within the drum. These baffles, which remain substantially stationary along with a rod lens 213 when the drum rotates, are substantially absorbing of all light across the visible spectrum. Stray light that is transmitted to the drum 200, but is reflected within the drum as it rotates is incident on one of the baffles and is absorbed. As such, the stray light that would otherwise be transmitted to the light valve and then to the screen is substantially absorbed by the baffles.
- white light 214 from a light source is incident on the rotating color drum 200.
- the white light 214 traverses the color filters on the near side of the color drum, the rod lens 213, and the color filters on the distal end of the color drum as the drum rotates.
- the primary colors are transmitted to the light-valve and then to the screen, via the filtering using the color filters of each respective color.
- the rotation of the drum effects a scrolling of the colors.
- light 215 that is incident on one of the shields 211 is prevented from entering the color drum 200 and thus the issues of stray unfiltered light are significantly reduced, if not substantially eliminated.
- FIG. 2b illustrates the use of the baffles 212 for absorbing stray light from a variety of sources.
- light 216 is incident on the drum at color filter 204.
- the light traverses the color filter 204, traverses the rod lens 213 and is incident on the color filter 209 at a relatively high angle of incidence, illustratively outside its tolerance angle.
- the filter 209 e.g., a dielectric stack
- some of the light 217 is reflected at the surface of the filter 209, and some is reflected from within the filter 209 (e.g., through known optical phenomena).
- reflected (stray) light components 217, 218 are substantially absorbed by the baffle 212 as shown, and are thereby prevented from being reflected within the color drum 200 and exiting the drum 200 at another point on the distal side. Thus, these stray components 217, 218 are prevented from being transmitted to the light- valve, where they may impact the scrolling sequence of the primary colors needed to create the image at the screen.
- Fig. 2b also shows how light 219, which is stray light from an aberration or other defect on the lens 205 is prevented from reaching the distal portion of the color drum 200 by virtue of the example embodiments.
- a portion of light 216 is reflected from the lens 105 at numerous locations as shown, emerging as light 219.
- This light 219 would otherwise be transmitted to the distal portion of the color drum 200 and would emerge as stray light, creating deleterious effects at the screen.
- the baffle 212 prevents this from occurring.
- Fig. 2c shows the prevention of stray light 222 from being transmitted to the light- valve in accordance with an example embodiment.
- stray light 222 is reflected within the lens 105 and is incident on the color filter 203 illustratively at an edge 224.
- This light 222 propagates through the color filter 203 being reflected by total internal reflection (TIR).
- TIR total internal reflection
- the color filter may act as a waveguide.
- the light emerges from the color filter 203, and otherwise may be transmitted to the light-valve.
- the baffle 212 absorbs this stray light and prevents its being transmitted to the light- valve.
- light 223 is light that is incident on the outer surface of the lens and is thus on the outer portion of the cone of light desirably transmitted from the light source. This light may not be properly scrolled and is beneficially absorbed by the baffle 212.
- light 225 has components that are reflected at least partially by elements of the drum 200, or the lens 106, or both. These reflected portions can be stray light to the system, and may be deleterious to the image. These reflected portions are thus absorbed by the baffles 212 as shown. It is emphasized that the light rays described in connection with the example embodiments of Figs. 2a- 2c are merely illustrative. Clearly, the deleterious stray light may have different trajectories and sources. Such stray light may also be substantially eliminated or significantly reduced by virtue of the example embodiments.
- Fig. 3 shows a color drum 300 in accordance with an example embodiment.
- the color drum 300 is similar to that described in the example embodiment of Figs. 2a-2c, however, is US040457
- the drum 300 includes a plurality of color filters 301-308, wherein each filter is disposed substantially directly opposite a filter that is substantially identical in dimensions and color filtration characteristics.
- color filter 301 is substantially the same as color filter 305, and is comparatively larger most other of the filter elements.
- filters 301 and 305 usefully increase the portion of a primary color (one of the four colors projected to the light valve) that is relatively deficient in the emission spectrum of the light source.
- the color drum may include substantially arcuate color filters, rather than the eight-sided drum shown. This provides a substantially cylindrical drum. In the example embodiment of Fig. 3, like the drum 200 of Figs.
- the drum 300 may include one or more substantially transparent elements selectively substituted for one or more color filters.
- the color filters do not have to be as described immediately above or arranged as described immediately above.
- the color filters may be the same size and it is not essential that a color filter is disposed substantially directly opposite another substantially identical filter.
- baffles 212 extend radially outward from rod lens 213 to the outer wall of color drum 200, as illustrated in Fig. 2, leaving enough clearance between the baffles and the drum to allow the drum to rotate freely, while the rod lens 213 and the baffles 212 remain substantially stationary.
- baffles 212 there are four baffles 212 disposed in a pseudo-juxtaposed relationship. This is merely illustrative. Clearly, more or fewer baffles may be used. One consideration is to ensure that the baffles do not interfere with light that traverses the rod lens, as this light is unlikely to be deleterious stray light.
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Abstract
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Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US62974804P | 2004-11-19 | 2004-11-19 | |
US60/629,748 | 2004-11-19 |
Publications (1)
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WO2006054253A1 true WO2006054253A1 (en) | 2006-05-26 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/IB2005/053788 WO2006054253A1 (en) | 2004-11-19 | 2005-11-16 | Color drum filter for projection system including light-absorbing baffles |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2413075A (en) * | 1941-01-31 | 1946-12-24 | Rca Corp | Method and system for developing television signals |
EP0977442A2 (en) * | 1998-07-31 | 2000-02-02 | Koninklijke Philips Electronics N.V. | Color projection system incorporating electro-optic light modulator and rotating light reflective element |
US6361172B1 (en) * | 2000-03-20 | 2002-03-26 | Philips Electronics North America Corporation | Color projection system incorporating electro-optic light modulator and rotating light-transmissive element |
US20030001990A1 (en) * | 2001-06-21 | 2003-01-02 | Corning Precision Lens Incorporated | Scrolling color sequential illumination system |
-
2005
- 2005-11-16 WO PCT/IB2005/053788 patent/WO2006054253A1/en active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2413075A (en) * | 1941-01-31 | 1946-12-24 | Rca Corp | Method and system for developing television signals |
EP0977442A2 (en) * | 1998-07-31 | 2000-02-02 | Koninklijke Philips Electronics N.V. | Color projection system incorporating electro-optic light modulator and rotating light reflective element |
US6361172B1 (en) * | 2000-03-20 | 2002-03-26 | Philips Electronics North America Corporation | Color projection system incorporating electro-optic light modulator and rotating light-transmissive element |
US20030001990A1 (en) * | 2001-06-21 | 2003-01-02 | Corning Precision Lens Incorporated | Scrolling color sequential illumination system |
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