Abstract:
The present invention discloses an optical energy collecting system for providing optical power to a display system for showing an image. The optical energy collection system includes an optical energy collecting system for collecting optical energy from a background illumination source surrounding and illuminating on the display system whereby an optical energy provided by said optical energy collecting system to said display system for illumination is naturally adjusted according to a background illumination of the background illumination source surrounding the display system.

Description:
[0001]    This Application claims a Priority Filing Date of Aug. 2, 2002 benefited from a previously filed Application 60/400,846 filed by the same inventors of this Application. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to light source for illumination and display system. More particularly, this invention relates to an improved light collection system for collecting and filtering optical energy from solar and different complimentary light sources to economically provide optical powers to the display or illumination systems at different time of the day with minimum wastes while accommodate comfortable viewing with brightness adjustments depending on viewer&#39;s background illumination.  
           [0004]    2. Description of the Prior Art  
           [0005]    [0005]FIG. 5 is a functional block diagram for showing an optical energy collecting system for implementation in a common display light projection (DLP) engine  200 . An optical energy collector includes a lamp  205  projects light onto an elliptic reflector  210  for reflecting and focusing the reflected light onto an integration tunnel  220  covered by a color wheel  230  to function as a color light source. The color light is projected through a set of ray lenses  235  and field lens  240  on to a total internal reflection (TIR) prism  245  in combination with a digital modulation display (DMD) panel  250  to generate image source for projecting through a projection lens  260  of a color image display system.  
           [0006]    A technical difficulty is still faced by those of ordinary skill the art of designing and making outdoor display systems for providing a light source suitable for different times of the day and varying background brightness situations. In the daytime of a sunny day, due to the very high intensity of illumination from the sun, a light source of high intensity is required to overcome the degradation of image display caused by the bright background. However, such strong light source would become too bright in the evening. Adjustments to the light source are necessary to provide comfortable viewing of an outdoor display. Additional sensing of the background light to adjust the intensity of the light source would be required. Furthermore, in order to overcome the high illumination of the sun, a high power light source would also be required. These requirements add to the cost and operational complexities of an outdoor display system. Additionally, a light source of high intensity often leads to other design concerns, such as light source overheating and other safety issues. These difficulties often limit a more effective applications of the outdoor display systems utilizing digital display technologies that can provide many different kinds of advantages over image displays implemented with conventional technologies.  
           [0007]    Therefore, an improved light source, particularly for outdoor digital image display, is still required to overcome these difficulties and limitations. It is desirable that such light source has an optical energy collecting system that can directly collecting the light from sun light such that the brightness of the display can be made substantially proportional to the background light. It is further desirable to take advantage of the sensing feature in collecting the solar energy to provide complimentary optical energy based on the sensed solar power collected by an outdoor solar light collector.  
         SUMMARY OF THE PRESENT INVENTION  
         [0008]    It is therefore an object of the present invention to provide an optical energy collection system for directly collecting optical energy from background illumination such that the intensity of the light source would substantially change in proportional to the background illumination such that the above-mentioned difficulties can be resolved.  
           [0009]    Specifically, it is an object of the present invention to provide an economical and highly functional sunlight energy collection system to collect solar energy and to filter and focus the sunlight into visible light source for image display system. Since the intensity of the light source would substantially proportional to the background illumination when the sunlight is focused and transmitted to a light source for a display system, the light source is most useful for outdoor large display. As the sunlight is strong and the background illumination is high, the light source is also providing high intensity image display. A comfortable viewing is provided without unnecessary wastes of illumination energy.  
           [0010]    Another object of the present invention is to provide a novel light source for a display system where the light source is complimented between a sunlight optical energy collector and lamp light collector such that the intensity of the light source for an image display system can be flexibly controlled to achieve optimal illumination intensity for comfortable viewing. The complimentary light source can be conveniently employed when the sunlight is dimmed during a cloudy day or after the sunset such that an outdoor display can be comfortably viewed during a high illumination and after-dark conditions.  
           [0011]    Another object of the present invention is to provide a visible light source from the sunlight radiations by first filtering the ultraviolet and infrared lights from the optical energy collected by the light collecting system of this invention. The invisible and potentially healthy hazardous radiations can be removed without being unduly applied in an image display system to further enhance the functionality and usefulness of the economical and environmentally sound display system.  
           [0012]    Briefly, in a preferred embodiment, the present invention discloses an optical energy collecting system for providing optical power to a display system for showing an image. The optical energy collection system includes an optical energy collecting system for collecting optical energy from a background illumination source surrounding and illuminating on the display system whereby an optical energy provided by said optical energy collecting system to said display system for illumination is naturally adjusted according to a background illumination of the background illumination source surrounding the display system.  
           [0013]    In a preferred embodiment, this invention further discloses a method for collecting optical energy for providing optical power to a display system for showing an image. The method includes a step of collecting optical energy from a background illumination source surrounding and illuminating on the display system by employing an optical energy collecting system whereby an optical energy provided by the optical energy collecting system to the display system for illumination is naturally adjusted according to a background illumination of the background surrounding the display system.  
           [0014]    These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment, which is illustrated in the various drawing figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 a  is a functional block diagram showing an optical energy collecting system of this invention for collecting optical energy from a background illumination source such as the sunlight;  
         [0016]    [0016]FIG. 1 b  is a schematic diagram for showing an optical energy collecting system from background light source such as sunlight with a Frensel lens of this invention  
         [0017]    [0017]FIG. 1 c  is a schematic diagram of a Frensel lens.  
         [0018]    [0018]FIG. 2 is a schematic diagram showing another optical energy collecting system of this invention for collecting optical energy in parallel from a background illumination source such as the sunlight;  
         [0019]    [0019]FIG. 3 is a schematic diagram showing another optical energy collecting system of this invention for collecting optical energy from a background illumination source such as the sunlight and a complementary light source employing a lamp;  
         [0020]    [0020]FIG. 4 is a schematic diagram showing an optical energy collecting system of this invention for collecting optical energy from a background illumination source such as the sunlight and distribute the light to a plurality of optical output ports;  
         [0021]    [0021]FIG. 5 is a schematic diagram showing an optical energy collecting system of the prior art employing a lamp wherein the optical energy collecting system serves as a DLP engine for a color image display system;  
         [0022]    [0022]FIG. 6 is a schematic diagram showing an optical energy collecting system of this invention for collecting optical energy from sunlight wherein the optical energy collecting system serves as a DLP engine for a color image display system;  
         [0023]    [0023]FIG. 7 is a schematic diagram showing an optical energy collecting system of this invention for collecting optical energy from sunlight and lamp wherein the optical energy collecting system serves as a DLP engine for a color image display system;  
         [0024]    [0024]FIG. 8 is a schematic diagram showing an optical energy collecting system of this invention for collecting optical energy from multiple lamps wherein the optical energy collecting system serves as a DLP engine for a color image display system;  
         [0025]    [0025]FIG. 9 a  is a schematic diagram showing an optical energy collecting system of this invention for collecting optical energy from sunlight and color separate the sunlight into RGB color components wherein the optical energy collecting system serves as a DLP engine for a color image display system;  
         [0026]    [0026]FIG. 9 b  is a schematic diagram for showing a cladding rod;  
         [0027]    [0027]FIG. 9 c  is a schematic diagram for showing a fiber rod;  
         [0028]    [0028]FIG. 10 a  shows a perspective view of a sunlight tracking system for tracking and rotating a sunlight collector to direct to the sun for maximizing efficiency of sunlight collection;  
         [0029]    [0029]FIG. 10 b  is a schematic diagram for showing a Frensel lens, a mirror with a rotational center and a cladding rod, e.g. an optical rod with the Frensel lens converges the sunlight to the mirror and reflects the sunlight to the fiber rod;  
         [0030]    [0030]FIG. 10 c  is a schematic diagram for showing the angle between the sunlight and mirror;  
         [0031]    [0031]FIG. 10 d  is a schematic diagram for showing the different position of FIG. 10 b ;  
         [0032]    [0032]FIG. 10 e  is a schematic diagram for showing the angular position of the mirror at noon time;  
         [0033]    [0033]FIG. 10 f  is a schematic diagram for showing the Frensel lens rotates Δφ, while the angle Γ 0 ′ between the mirror and the focused beam projected from the edge of the Frensel lens must be greater than zero degree;  
         [0034]    [0034]FIG. 11 is a schematic diagram for illustrating a sunlight regulating system of this invention; and  
         [0035]    [0035]FIG. 12 is a schematic diagram for illustrating a mobile outdoor display system of this invention implemented with a sunlight collecting system as shown in FIGS.  1  to  11  but FIG. 5.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0036]    [0036]FIG. 1 a  is a schematic diagram showing an optical energy collecting system  100  of this invention for collecting optical energy from a background illumination source, e.g., the sunlight  105 . The optical energy collecting system  100  includes a parabolic reflector  110  for reflecting and focusing the sunlight  105  onto an optical fiber  120  through an ultraviolet (UV) and infrared (IR) filter  115  to filter out the invisible light before the reflected light is focused onto the optical fiber  120 . The filtered light with only the visible light then transmitted from the optical fiber  120  through a waveguide or an optical fiber extension  125  to an optical output port  130 . FIG. 1 b  shows another embodiment by using a Frensel lens instead of the parabolic reflector as shown in FIG. 1 a . The Frensel lens  111 ′ focuses the incident sunlight  105  onto an optical fiber  120 . Specifically, as shown in FIG. 1 c , the Frensel lens  111 ′ has a width of 600 millimeters and a length of 590 millimeters, the Frensel lens  110 ′ has a focal length of 706 millimeters. FIG. 2 is another functional block diagram for showing an alternate optical energy collecting system  100 ′ similar to that shown in FIG. 1 except that there are two parallel parabolic reflectors  110  and  110 ′ to collect the sunlight through optical fibers  120  and  120 ′. The collected and filtered visible light is then transmitted through the optical fiber extensions  125  and  135 ′ to an output port  130 .  
         [0037]    Table 1 shows the optical energy collection during different times of the day where the illumination in the unit of “Lux” is measured by a illumination sensor Minolta T-10. From Table 1, the optical power provided to a display system during different times of a day is substantially changed in proportional to the brightness of the background. Therefore, a comfortable viewing of an outdoor display can be achieved without wastes of employing optical source of great power for the purpose of overcoming a strong background illumination when there is a strong sunlight.  
                                                         TABLE 1                           Optical Energy Collection during different times of a Day            Time   9:00   10:00   11:00   12:00   13:00   14:00   15:00   16:00   17:00               Temperature                           32C               Humidity                           35C       Illumination-   56600   69800   79900   81600   89000   86500   82400   58000   31700       Inclined to       Sun (Lux)       Illumination-   49500   65600   75200   81400   82000   71000   60000   36100   14630       Horizontal       (Lux)                  
 
         [0038]    Where 56600 lux×1 m 2  (area)=56600 lum˜870W UHP lamp. And UHP 65 lum/W (100 W UHP˜6500 lm).  
         [0039]    [0039]FIG. 3 is another schematic diagram for showing an alternate optical energy collecting system  100 ″ similar to that shown in FIG. 1 except that there are two parallel parabolic reflectors  110  and  110 ′ and also a lamp  135  serving as a complimentary light source to project light onto an elliptic reflector  140  for reflecting and focusing the light onto an optical fiber  150  for transmitting the reflected light to the optical output port  130 . FIG. 4 is another schematic diagram for showing the optical energy collecting system  100  similar to that shown in FIG. 1 except that there are the extended optical fiber  125  is now separated into three optical fibers  125 - 1 ,  125 - 2 , and  125 - 3  for providing light source to three optical output ports,  130 - 1 ,  130 - 2 , and  130 - 3 .  
         [0040]    [0040]FIG. 6 is a schematic diagram for showing an alternate optical energy collecting system, for implementation in an identical digital light processing (DLP) engine  200 ′. Instead of employing a lamp as light source, the optical energy collection system is a solar optical energy light collector that includes a parabolic reflector  210 ′ to reflect and focusing sunlight through an UV and IR filter  212  into an optical fiber  215  for transmitting the filtered visible light to an optical fiber port  218  disposed immediately next to the integration channel  220 . FIG. 7 shows a novel engine collecting optical energy from the sunlight by the parabolic reflector  210 ′ and the elliptic reflector  210  from the lamp that functions as a complimentary light source. FIG. 8 shows an DLP engine of this invention and the optical energy is collected from a multiple light sources in parallel using a plurality of lamps, e.g., lamps  205 - 1 ,  205 - 2 ,  205 - 3 , and  205 - 4 , as light sources, to function as a combined light source for the display system. This DLP engine is intended for use in compliment to the sunlight energy collector during a cloudy day when the sunlight is weak or not available.  
         [0041]    [0041]FIG. 9 a  is another schematic diagram for illustrating the configuration of another DLP engine where the light collected from the sunlight collector as shown in FIGS.  1  to  4  are processed by a laser diode (LD) or light emission diode (LED) module for projecting red, green and blue lights (RGB) onto a fiber  218  disposed immediately next to the integration channel to provide color lights to the display projection system. FIGS. 9 b  and  9   c  show a single core single cladding optical fiber  218 - 1  and a multi-core, multi-cladding optical fiber  218 - 2  respectively implemented for the fiber  218 - 1  of FIG. 9 a.    
         [0042]    Referring to FIG. 10 a  for a sunlight tracking system of this invention. The sunlight tracking system includes a base  270  for supporting a light collector  280  on a rotational shaft  275 . In order to optimize the efficiency of sunlight collection, the sunlight collection base  270  and the sunlight collector  280  are provided to have rotational flexibility along at least two of the three different axes shown as X-Y-Z axes. In a preferred embodiment, the base  270  can rotate along a Z-axis while the sunlight collector  280  is provided to rotate along an X-axis. The rotation of the base  270  and the collector  280  are provided to tracking and focusing on the sun at different time of the day as the earth rotates and moves around the sun. A motor (not shown) is employed to actuate the rotation of the sunlight tacking system base  270  and the motor is controlled and driven by a sunlight collection guiding means (not shown) that includes a processor executing a program using astronomical data that includes the location of the sunlight collection system, the equatorial coordinates and the date and time of sunlight collection to determine an optimal orientation of the sunlight collector. The sunlight collection guiding means further includes a real time feedback system receiving a, real-time sunlight collection data obtained directly from the sunlight collector to further fine tune and adjust the orientations of the base and the collector to optimize the collection of the energy received from the sun.  
         [0043]    [0043]FIG. 10 b  shows another optical energy collection system  300  of this invention implemented with a Frensel lens  305  coated with an infrared (IR) filter  310 . The IR filter  310  can be coated onto the Frensel lens  305 . The Frensel lens focus the sunlight  320  onto a mirror  315  for reflecting the reflected beam  325  onto an optical fiber  330 . The Frensel lens  305  and the IR filter  310  are supported and fixed on a rotational frame  350  that are rotatable around a rotation pivot 360 . The mirror  315  is also rotational around the rotation pivot  360 . FIGS. 10 c  and  10   d  show the relative rotation angle between the Frensel lens and the mirror  315  at different times of the day where the Frensel lens  305  and the IR filter  310  are tracking the sun for the purpose of collecting maximum amount of optical energy. In the meantime, the mirror  315  is rotated relative to the rotation of the Frensel lens  315  to reflect the collected sunlight onto the optical fiber  330 . FIGS. 10 e  and  10 F show a functional relationship between the angular rotations of the mirror  315  and the Frensel lens  305 . FIG. 10 e  shows the angular position of the mirror  315  at noon time when the sunlight is projected vertically unto the Frensel lens and there is an incline angle of θ 0  between the mirror  315  the direction of a focused beam  320 ′ projected from the edge of the Frensel lens  305 . In FIG. 10 f , the Frensel lens  305  rotates Δφ, while the angle θ 0 ′ between the mirror  315  and the focused beam  320 ′ projected from the edge of the Frensel lens  305  must be greater than zero degree. Meanwhile, as the Frensel lens  305  is rotated Δφ degree, the mirror  315  must rotate Δφ/2. Therefore, θ 0 −Δφ+(Δφ/2)&gt;0 and the maximum angular rotation allowable for the Frensel lens is: Δφ&lt;2θ 0 . The maximum allowable rotation of the Frensel lens is 2θ 0  and the maximum allowable rotation angle of the mirror  330  is θ 0 . Meanwhile, for the purpose of improving the optical energy collection, the optical fiber  330  is formed as a tapered rod having a larger end area facing the mirror  315  and gradually reduces in the cross sectional area for coupling to a regular optical fiber to transmit the collected optical energy to an optical engine whereby the sunlight collecting system can achieve a function as an optical light source.  
         [0044]    Referring to FIG. 11 for a sunlight regulating and control system  440  of this invention. A light luminance detector  410 , e.g., Wheatstone Bridge having conductive lines  412  connected two resistors  413  and a variable resistor  416  and a photoconductive cell  414  is employed for detecting luminance of light to generate a signal corresponding to the luminance of the detected light. A light luminance selector  400  that includes a motor  402  and a disk  404  having different levels of transparency is implemented for proving different levels of light luminance filter corresponding to the signal of light luminance detector  410 . A light splitter  406  to reflect 10% of the sunlight to a luminance detector  410 , e.g., the Wheatstone Bridge and a photoconductive cell  414 , for detecting the luminance of sunlight, and 90% of the sunlight is transmitting to DLP engine. When the luminance of sunlight is under a preset value where a variable resistor is implemented to set the preset luminance value, a motor  402  is employed to drive a disk  404  to a proper level of transparency to regulate the sunlight transmission to the DLP engine  420 .  
         [0045]    [0045]FIG. 12 shows a new configuration for a mobile display system  500  of this invention implemented with the optical energy collection system  300  and a sunlight energy collector shown in FIGS.  1  to  11  above. The mobile display system is carried on a motor vehicle  460  that has a back area implemented as a display area  430  for displaying images using image signals received from a wireless signal receiver  490  supported on the motor vehicle  460 . The motor vehicle  460  further carries and supported on a sunlight energy collector  300  on a platform  425  to transmit the sunlight energy via an optical fiber optical transmitting cable  330  to a light luminance controller  440  and a DLP engine  420  for providing light source to a display system (not shown) also carried on the motor vehicle  460 . The motor vehicle  460  may also include a side sliding door  470  to slid up and down for the purpose of either using the image display screen  430  for display when the sliding door is pulled up or to cover and protect the image display  430  when the sliding side door is pulled down. The platform  425  may also be controlled by a motor (not shown) to lift up to the top of the motor vehicle as shown for collecting sunlight energy or pulled down and enclosed inside the trailer of the motor vehicle  460  for protection and for transporting to different geographical locations for the purpose of outdoor display.  
         [0046]    Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alternations and modifications will no doubt become apparent to those skilled in the art after reading the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alternations and modifications as fall within the true spirit and scope of the invention.