Patent Application
20060274284
Disclosed embodiments of the present invention relate to the field of projection systems, and more particularly to the combination of light paths from light sources in such projection systems.
Multimedia projection systems have become popular for purposes such as conducting sales demonstrations, business meetings, classroom training, and for use in home theaters. In typical operation, multimedia projection systems receive video signals from a data source and convert the video signals to digital information to control one or more digitally driven light valves. Based on this digital information the light valves may manipulate incident light into image bearing light that represents the video image. High-energy discharge lamps emitting polychromatic light have often been used in prior art projection systems. These prior art projection systems suffer from a number of disadvantages including a short lamp life and reduced brightness after an initial period of usage. Additionally, there is a significant amount of resources directed to dividing the polychromatic light in order to selectively manipulate light of the primary colors.
Recent focus has turned to developing and manufacturing projection systems employing and utilizing the monochromatic light of solid state light sources, which are less affected by the shortcomings of polychromatic light sources. One challenge of using multiple monochromatic light sources in projection systems is to combine the light from the light sources, while being cognizant of the reliability, performance, package dimensions, and cost of the projection systems.
Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which the like references indicate similar elements and in which:
In the following detailed description reference is made to the accompanying drawings that form a part hereof, wherein like numerals designate like parts throughout, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the embodiments of the present invention. Directions such as up, down, back, and front may be used in the discussion of the drawings. These directions are used to facilitate the discussion and are not intended to restrict the application of embodiments of this invention. Therefore, the following detailed description is not to be taken in a limiting sense and the scope of the embodiments of the present invention are defined by the appended claims and their equivalents.
For the purposes of the present invention, the phrase “A/B” means A or B; the phrase “A and/or B” means “(A), (B), or (A and B)”; the phrase “A, B, and/or C” means “(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C)”; and the phrase “(A)B” means “(B) or (AB),” that is, A is an optional element.
In one embodiment, another green light source 112 may also provide light within the green wavelength range, e.g., 500-560 nanometers (nm). A filter 116 may be adapted to transmit light from the light source 108 and reflect light from the light source 112 toward the integrating device 104.
In an embodiment, the two green light sources 108 and 112 may provide green light with slightly different wavelengths. In this embodiment, the filter 116 may be a dichroic filter adapted to allow light from the green light source 108 to pass, while reflecting light from the green light source 112. For example, the green light source 108 may provide light with an average wavelength of approximately 540 nanometers (nm), while the green light source 112 may provide light with an average wavelength of approximately 520 nm. The filter 116 may be a dichroic edge filter adapted to allow light with wavelengths greater than 530 nm to pass while reflecting light with wavelengths below 530 nm.
In another embodiment, the filter 116 may be a polarization filter adapted to reflect light of one polarization and to transmit light of an orthogonal polarization. For example, the light source 108 may emit vertically polarized light and the light source 112 may emit horizontally polarized light. In this embodiment, the filter 116 may transmit horizontally polarized light, such as the light from the light source 112, and reflect vertically polarized light, such as the light from the light source 108.
In various embodiments, the light sources 108 and/or 112 may have a variety of polarization components adapted to result in the emission of appropriately polarized light. Furthermore, in various embodiments additional/alternative polarizations may be used.
A blue light source 120 may provide light within the blue wavelength range, e.g., 440-485 nm. A filter 124 may reflect the light from the blue light source 120 and allow light from the green light sources 108 and 112 to pass.
A red light source 128 may provide light within the red wavelength range, e.g., 625-740 nm. A filter 132 may reflect light from the red light source 128 towards the integration device 104, and transmit light from the green light sources 108 and 112 and from the blue light source 120.
In various embodiments, illumination arrangements described herein may have modifications such as adding/removing light sources, additional/alternative colors (e.g., yellow and/or cyan), and/or alternative placements of the colored light sources with appropriate modifications to the filters used.
In one embodiment, filters may include dichroic interference filters. In other embodiments, other types of filters such as other interference filters may be utilized. Additionally, the filters may be notch filters and/or edge filters as appropriate. For example, while the above embodiment teaches combining green light with filter 116, other embodiments may additionally/alternatively combine other like-colored light paths in a similar manner.
Illumination arrangements described herein may allow the flexibility of increasing the intensity of one or more colors by adding light sources of that color. Increasing the intensity of a particular color may be desirable in order to obtain a more preferred color balance for the projection system. Illumination arrangements of the present embodiment may also increase the color gamut by allowing for more colored light sources (e.g., yellow and/or cyan) to be employed. These arrangements may also help to reduce the cost and overall dimensions of the projector system, compared to having separate integrating tunnels for each color. Furthermore, the light from the light sources may be presented to the tunnel along a single light path. The single light path may assist in the conservation of the projection system's étendue, or light throughput, by presenting different colored light having similar illumination areas and angles to downstream components.
As shown, each of the colored light sources 108, 112, 120, and 128 include a light emitting device and a lenses. Other embodiments may include additional/alternative components, e.g., mirrors, polarization elements, etc. The light emitting device may comprise solid-state light sources such as, but not limited to, light-emitting diodes and/or laser diodes.
A red light source 224 may provide red light to be transmitted through a filter 228 and reflected off of a filter 232 towards the integration device 216.
A blue light source 236 may provide blue light that is reflected off of the filter 228 and the filter 232 towards the integration device 216.
A second X-cube 320 may be adapted to transmit light from the blue light source 312 and the green light source 308 to the integration device 316. The second X-cube may have a filter 322 that is also adapted to reflect light from a green light source 324 and transmit light from a red light source 328, and transmit. Similar to the embodiment discussed above with respect to
The second X-cube may also have a filter 326 adapted to transmit light from the green light source 324 and reflect light from the red light source 328. In one embodiment, the integration device 316 may be adjacent to the second X-cube 320. In other embodiments, a lens may positioned between the two components.
In various embodiments, an additional light source may be placed on the face of the X-cube 304 opposite the tunnel 316 and/or additional X-cubes may be added.
A red light source 424, placed adjacent the second green light source 416, may provide red light that may be reflected off of a filter 428. The filter 428 may be adapted to transmit green light from the green light sources 408 and 416.
A blue light source 432, placed adjacent to the red light source 424, may provide blue light that may be reflected off of a filter 436. The filter 436 may be adapted to transmit green and red light.
In this embodiment, the light sources 408, 416, 424, and 432 may be arranged in the same plane. This planar configuration may allow for the precise placement of the light emitting devices with, e.g., a pick-and-place machine, on a common board. This may, in turn, facilitate the alignment and/or the reduction in manufacturing costs. Additionally, this may facilitate the cooling of the light emitting devices. The cooling of the devices could take place by thermally coupling a heat sink to the board and/or by directing an air current over the devices.
In various embodiments, other light sources may be additionally/alternative placed on the upstream end of the integration device 404 and/or the side opposite from where the light sources are located as depicted in
In this embodiment, the filter 628 may be disposed substantially parallel/collinear with a light path of the light received from the red light source 604. This arrangement may allow a portion of the red light to be incident on the filter 620 and reflected towards the tunnel 624 without being transmitted through the filter 628. Additionally, the amount of red light incident upon the intersection of the filter 620 and the filter 628, where filtering may be inconsistent, may be reduced. This orientation of the red light source 604 and the crossed filter device 616 may lessen the amount of red light that gets inadvertently filtered.
As used herein, a filter may be parallel/collinear with a light path if a line in the plane of the filter is parallel/collinear with the light path.
Similar to filter 628, the filter 620 may be disposed substantially parallel/collinear with a light path of the light received from the light source 612. Likewise, this orientation may lessen the amount of blue light that gets inadvertently filtered. In this embodiment a filter angle φ of approximately 30 degrees may be formed at the intersection between the filter 620 and the filter 628.
A filter angle φ of approximately 30 degrees, along with relative positioning of light sources 604 and 612, may result in a lower angle of incidence on the reflective filter (as compared to having a 45 degree filter angle φ. This may be beneficial (for both polarizations) by reducing an occurrence of s-p polarization splitting, which may, in turn, result in higher reflection rates of the light.
The transmissive light path, e.g., from the green light source 608, may encounter an increased cross-sectional area at the intersection of the two filters 620 and 628 as the filter angle φ decreases. Therefore, in one embodiment, this cross-sectional area may be reduced by using relatively thin (e.g., 0.7 millimeters (mm), 0.5 mm, or even 0.3 mm) filters. This may facilitate a reduction in the loss of light for the transmissive path at the intersection.
Furthermore, having thin filters may reduce the surface area orthogonal to the collinear/parallel light path. In some embodiments edges of the filters 620 and 628 may also be cut at angles other than 90 degrees (e.g., at 60 degrees) to decrease this surface area.
Other embodiments described and discussed in accordance with embodiments of the present invention may be amenable, with proper modifications, to coupling light from light sources arranged in a planar configuration with reflecting devices similar to this embodiment.
Placing filter coatings on surfaces of a prism may facilitate the alignment of the filters.
The light paths are shown separate from one another for clarity of the description. Embodiments of the present invention may include co-linear light paths.
In this embodiment, the selective reflection and/or transmission of the filter coating 924 and filter coating 928 may facilitate reduction of the colored light paths to a substantially common output light path to the integration device 920.
The prism 1004 may have a filter coating 1024 on a first surface adapted to reflect red light from the light source 1008 and to transmit green and blue light from the green and blue light sources 1012 and 1016, respectively. The prism 1004 may also have a filter coating 1028 on a second surface adapted to transmit green light from the light source 1012 and to reflect blue light from the light source 1016. In this embodiment, the blue light from the light source 1016 may be internally reflected from the first surface prior to being reflected from the filter coating 1028 at the second surface.
Similar to the above embodiments, the light paths are shown separate from one another for clarity of the description. Embodiments of the present invention may include co-linear light paths.
In this embodiment, similar to the embodiment described with reference to
The projection device 1104 may include an illumination arrangement 1112 similar to any of the illumination arrangements described and discussed above. Light emitted from the illumination arrangement 1112 may propagate along a light path to illuminate an imaging device such as a light modulator 1116. The light modulator 1112 may include, but is not limited to, a digital micromirror device (DMD), a reflective liquid crystal on semiconductor (LCOS) device, and a liquid crystal device (LCD).
The light modulator 1116 may modulate the light based on control signals provided to the light modulator 1116 from a controller 1120. The controller 1120 may receive color image data representing a color image from the data source 1108 and process the image data into constituent color data (e.g., red, green, and blue data). The constituent color data may then be conveyed to the light modulator 1116 in proper synchronism with signals sent to a power supply 1124 that control emission time frames of the corresponding constituent colored light sources (e.g., red, green, and blue light sources) of the illumination arrangement 1112. In various embodiments, the controller may include a general-purpose processor/controller, an application specific integrated circuit (ASIC), or a programmable logic device (PLD).
For the purpose of this description, a still image may be considered as a degenerate or special video where there is only one frame. Accordingly, both still image and video terminologies may be used in the description to follow, and they are not to be construed to limit the embodiments of the present invention to the rendering of one or the other.
An image of the light modulator 1116 may be projected for viewing by a projection lens 1128. Various optical components may be placed in the light paths to adjust for specific design factors associated with a given embodiment.
In one embodiment, the optical components may be held together by an optical frame within a projector housing (not shown). The housing may be mechanically rigid and be designed to facilitate the dissipation of heat. The frame and housing may be adapted to accommodate a cooling fan for cooling the optical components by generating an airflow. The power supply may also be used to power the cooling fan and a controller.
Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiment shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
The present application is a non-provisional application of provisional application No. 60/686,344, filed on May 31, 2005, entitled “ILLUMINATION ARRANGEMENTS FOR COLORED LIGHT EMITTING DEVICES,” and claims priority to said provisional application. The specification of said provisional application is also hereby fully incorporated by reference in its entirety, except for those sections, if any, that are inconsistent with this specification
| Number | Date | Country | |
|---|---|---|---|
| 60686344 | May 2005 | US |
