Abstract:
In accordance with embodiments, viewable images can be created in glass. Viewable images may be created in glass by using a projector which projects ultraviolet light to excite light emitting material. Clear images may be created in glass because the size the light emitting particles in the glass is less than 400 nanometers. In embodiments, the visible illumination of a transparent substrate to display an image is possible, while the transparent substrate remains transparent. Accordingly, for example, drivers of automobiles may view images (e.g. map images) on their windshield while they are driving. As another example, window shoppers may view enhanced advertisements in the windows of stores that they are approaching.

Description:
Priority is claimed to U.S. Provisional Patent Application No. 60/563,376 (filed in the U.S. Patent and Trademark Office on Apr. 19, 2004), U.S. Provisional Patent Application No. 60/579,067 (filed in the U.S. Patent and Trademark Office on Jun. 10, 2004), U.S. Provisional Patent Application No. 60/586,746 (filed in the U.S. Patent and Trademark Office on Jul. 10, 2004), U.S. Provisional Patent Application No. 60/590,469 (filed in the U.S. Patent and Trademark Office on Jul. 24, 2004), U.S. Provisional Patent Application No. 60/598,527 (filed in the U.S. Patent and Trademark Office on Aug. 3, 2004), U.S. Provisional Patent Application No. 60/599,826 (filed in the U.S. Patent and Trademark Office on Aug. 7, 2004), U.S. Provisional Patent Application No. 60/626,152 (filed in the U.S. Patent and Trademark Office on Nov. 8, 2004), U.S. Provisional Patent Application No. 60/645,245 (filed in the U.S. Patent and Trademark Office on Jan. 20, 2005), U.S. Provisional Patent Application No. 60/658,242 (filed in the U.S. Patent and Trademark Office on Mar. 3, 2005), which are all herein incorporated by reference in entirety. 
    
    
     BACKGROUND 
     The reproduction of images has had a positive effect on many people&#39;s lives. One of the earliest technologies for reproducing images was the movie projector, which allowed for audiences to view theatrical productions without live actors and actresses. Televisions were invented, which allowed people to watch moving pictures in the comfort of their own homes. The first televisions were cathode ray tube (CRT) televisions, which is a technology that is still being used today. During the computer age, it has been desirable to reproduce images which are output from computers through monitors. Like many televisions, many computer monitors use CRT technology. 
     Other technologies have been developed as substitutes for CRT technology. For example, liquid crystal display (LCD) technology is commonplace for both computer monitors and televisions. A LCD is a relatively thin display, which is convenient for many people. Other examples of displays are plasma displays, rear projections displays, and projectors. As display technology has improved, many new applications are being developed. For example, many attempts have been made to develop displays which create viewable images in glass. However, there have been many technical challenges that have prevented creation of viewable images in glass or other transparent material. Specifically, it has been difficult for glass to be maintained in a substantially transparent state and be able to display viewable images with sufficient illumination and clarity. 
     SUMMARY 
     In accordance with embodiments, viewable images can be created in glass. Viewable images may be created in glass by using at least one ultraviolet light source (e.g. a projector) to excite light emitting material. Clear images may be created in glass because the size the light emitting particles in the glass is relatively small (e.g. less than 500 nanometers). In embodiments, the visible illumination of a transparent substrate to display an image is possible, while the transparent substrate remains transparent. Accordingly, for example, drivers of automobiles may view images (e.g. map images) on their windshield while they are driving. As another example, window shoppers may view enhanced advertisements in the windows of stores that they are approaching, while the windows remain transparent. In embodiments, different colors may be illuminated on glass by adjusting the wavelength of the ultraviolet light to create color images. 
     Embodiments relate to an apparatus including a light source, a projection modulator, and a variable light filter. The projection modulator is configured modulate light emitted from the light source. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light include light with a wavelength less than 500 nanometers. 
     Embodiments relate to a method including emitting light from a light source, modulating the light at a projection modulator, and filtering the light at a variable light filter. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light include light with a wavelength less than 500 nanometers. 
     Embodiments relate to a method including integrating a light source, a projection modulator, and a variable light filter into a projector. The projection modulator is configured modulate light emitted from the light source. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light comprise light with a wavelength less than 500 nanometers. 
    
    
     
       DRAWINGS 
         FIG. 1  is an example diagram of a substantially transparent display. 
         FIG. 2  is an example diagram of a transparent display illuminated with excitation light from a projector. 
         FIG. 3  is an example diagram of light emitting particles integrated into a substantially transparent substrate. 
         FIG. 4  is an example diagram of a micro mirror device, illustrating general operation characteristics when used in a projector. 
         FIG. 5  is an example diagram illustrating direct reflection operation of a micro mirror device. 
         FIGS. 6 and 7  illustrate example relationships of components of a projector that includes a micro mirror device. 
         FIGS. 8 through 11  illustrate examples of different variable light filters. 
     
    
    
     DESCRIPTION 
       FIG. 1  is an example diagram of a substantially transparent display, in accordance with embodiments. Viewer  110  is able to see an arbitrary object (e.g. cube  112 ) through substrate  114 . Substrate  114  may be transparent or substantially transparent. While viewer  110  sees arbitrary object  112  through substrate  114 , the viewer can also see images (e.g. circle  115  and triangle  116 ) that are created at substrate  114 . Substrate  114  may be part of a vehicle windshield, a building window, a glass substrate, a plastic substrate, a polymer substrate, or other transparent (or substantially transparent) medium that would be appreciated by one of ordinary skill in the art. Other substrates may complement substrate  114  to provide for tinting, substrate protection, light filtering (e.g. filtering external ultraviolet light), and other functions. 
       FIG. 2  is an example diagram of a transparent display illuminated with excitation light (e.g. ultraviolet light) from a projector  118 , in accordance with embodiments. Substrate  114  may receive excitation light from projector  118 . The received excitation light may be absorbed by light emitting material at substrate  114 . When the light emitting material receives the excitation light, the light emitting material may emit visible light. Accordingly, images (e.g. circle  115  and triangle  116 ) may be created at substrate  114  by selectively illuminating substrate  114  with excitation light. 
     The excitation light may be ultraviolet light, in accordance with embodiments. If the excitation light is ultraviolet light, then when the light emitting material emits visible light in response to the ultraviolet light, a down-conversion physical phenomenon occurs. Specifically, ultraviolet light has a shorter wavelength and higher energy than visible light. Accordingly, when the light emitting material absorbs the ultraviolet light and emits lower energy visible light, the ultraviolet light is down-converted to visible light because the ultraviolet light&#39;s energy level goes down when it is converted into visible light; In embodiments, the light emitting material is fluorescent material. 
     In embodiments illustrated in  FIG. 2 , the excitation light is output by projector  118 . Projector  118  maybe a digital projector. In embodiments projector  118  is a micro mirror projector (e.g. a digital light processing (DLP) projector). Projector  118  may include a micro-mirror array (MMA). In embodiments, projector  118  includes a digital micromirror device (DMD). In other embodiments, projector  118  includes an analog micromirror device. Projector  118  includes a variable light filter which is tailored to the ultraviolet light spectrum. In embodiments, the variable light filter is a color wheel with at least two light filters that let different ranges of ultraviolet light pass. 
       FIG. 3  is an example diagram of light emitting material (e.g. light emitting materials  178 ,  180 , and/or  182 ) integrated into a substantially transparent substrate, according to embodiments. When excitation light is absorbed by the light emitting materials  178 ,  180 , and/or  182 , the light emitting materials emit visible light. Accordingly, when ultraviolet light is absorbed by light emitting materials  178 ,  180 , and/or  182 , visible light is emitted from the light emitting materials. In embodiments, each of light emitting materials  178 ,  180 , and/or  182  may be a different type of light emitting material, which emits a different range of wavelengths of visible light in response to a different range of wavelengths of excitation light (e.g. ultraviolet). The different ranges of wavelengths of excitation light may be controlled by a variable light filter. Light emitting material can be integrated in a substantially transparent substrate in a variety of ways. As examples, light emitting materials can be dispersed in a substrate (as shown in example  FIG. 3 ), layered on a substrate, and disposed on a surface of a substrate. 
     Light emitting material (e.g. light emitting materials  178 ,  180 , and/or  182 ) may be fluorescent material, which emits visible light in response to absorption of electromagnetic radiation (e.g. visible light, ultraviolet light, or infrared light) that is a different wavelength than the emitted visible light. Light emitting material may include light emitting particles. The size of the particles may be smaller than the wavelength of visible light, which may reduce or eliminate visible light scattering by the particles. Examples of particles that are smaller than the wavelength of visible light are nanoparticles, individual molecules, and individual atoms. 
     According to embodiments, each of the light emitting particles has a diameter that is less than about 500 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 450 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 420 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 400 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 300 nanometer. According to embodiments, each of the light emitting particles has a diameter that is less than about 200 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 100 nanometers. According to embodiments, each of the light emitting particles has a diameter that is less than about 50 nanometers. The light emitting particles may be individual molecules or individual atoms. 
     Different types of light emitting particles (e.g. light emitting materials  178 ,  180 , and/or  182 ) may be used together that have different physical characteristics. For example, in order to create color images in substrate  114 , different types of light emitting particles may be utilized that are associated with different colors. For example, a first type of light emitting particles may be associated with the color red, a second type of light emitting particles may be associated with the color green, and a third type of light emitting particles may be associated with the color blue. Although the example first type, second type, and third type of light emitting particles are primary colors, one of ordinary skill in the art would appreciate other combinations of colors (e.g. types of colors and number of colors) in order to facilitate a color display. 
     In down-conversion embodiments (e.g. absorption of ultraviolet light to emit visible light), light emitting particles which emit red light may include Europium, light emitting particles which emit green light may include Terbium, and/or light emitting particles which emit blue or yellow light may include Cerium (and/or Thulium). In embodiments, light emitting particles which emit blue light may include Erbium. In embodiments, light emitting materials which emit blue light may include an organic fluorescent dye. 
     Different types of light emitting particles may absorb different ranges of excitation light to emit the different colors. Accordingly, the wavelength range of the excitation light may be modulated to control the visible color emitted from the light emitting particles in substrate  114 . In embodiments, different types of light emitting particles may be mixed together and integrated into substrate  114 . By modulating the wavelength of the excitation light, visible light with specific color characteristics can be created in substrate  114 . For example, by selectively exciting specific combinations of different types of light emitting particles associated with primary colors, virtually any visible color can be emitted from substrate  114 . In embodiments, modulating of the excitation light wavelength can utilize a variable light filter. In embodiments, the variable light filter is a color wheel with specific ultraviolet pass filters. 
       FIG. 4  is an example diagram illustrating operation of a projector which uses micro mirror device  10 , in accordance with embodiments. However, other implementations and configurations of a projector can be appreciated, in accordance with embodiments. The projector may include light source  9  (e.g. a lamp), micro mirror device  10 , projection lens  11 , and absorption plate  13 . Micro mirror device  10  may receive light output from light source  9  and may reflect the incident light at an angle in accordance with a control signal input to micro mirror device  10 . Projection lens  11  may focus light reflected from micro mirror device  10  onto screen  15  when a corresponding mirror is at a first angle. Absorption plate  13  may absorb light reflected off of micro mirror device  10  when a corresponding mirror is at a second angle. Accordingly, light can be either projected onto screen  15  or absorbed at absorption plate  13 , depending on an angle of each respective mirror of micro mirror device  10 . Micro mirror device  10  may include an array of micro mirrors which can be selectively controlled to form images on screen  15 . 
     In embodiments, light source  9  may output ultraviolet light. Light source  9  may be a gas discharge lamp, a solid state lamp, a light emitting diode lamp, and/or a metal halide lamp. Other types of lamps that can output ultraviolet light can be appreciated. Light source  9  may include a reflector. In embodiments, the reflector has a reflective enhancement coating. In embodiments, the reflective enhancement coating reflects light having a wavelength less than 500 nanometer. In embodiments, the reflective enhancement coating reflects light having a wavelength less than 450 nanometer. In embodiments, the reflective enhancement coating reflects light having a wavelength less than 420 nanometer. In embodiments, the reflective enhancement coating reflects ultraviolet light. 
     Micro mirror device  10  may include blackboard  1 , a plurality of electrodes  3 , micro mirrors  5 , and support  7 . Plurality of electrodes  3  may be coupled to the blackboard  1 . Micro mirrors  5  may receive light output from light source  9  and selectively reflect the light at different angles to form images on screen  15 . Support  7  mechanically supports micro mirrors  5 . 
     Plurality of electrodes  3  may generate an electrostatic field by an input voltage signal to modulate movements of supporting member  7 . Micro mirrors  5  (which may be relatively small) may be attached to supporting member  7  and rotated at a relatively small angle. Light is reflected from light source  9  to either projection lens  11  or absorption plate  13 , depending on the angle of micro mirror  5 . Projection lens  11  may receive light reflected from micro mirror device  10  and project the light to the screen  15  to display an image. 
     Micro mirrors  5  may be slanted at an initial angle. When light output from light source  9  is projected onto micro mirrors  5 , micro mirrors  5  reflect the light to absorption plate  13 . Accordingly, under these circumstances, since micro mirrors  5  do not reflect light to projection lens  11 , a blank image (e.g. black image) appears on screen  15 . 
     When a signal is input to plurality of electrodes  3  on blackboard  1 , plurality of electrodes  3  may generate an electrostatic field which selectively causes supporting member  7  to rotate within a sufficient angle range. When micro mirrors  5  are rotated at an appropriate angle, light incident on micro mirrors  5  is reflected to projection lens  11 , which projects the light onto screen  15 , causing selective illumination of pixels (associated with rotated micro mirrors  5 ). Micro mirrors  5  may be selectively rotated at high speeds (e.g. on/off operations) to produce a moving (or static) image on screen  15 . 
       FIG. 5  is an example illustration of a projector operating with direct reflection off of micro mirror device  20 , in accordance with embodiments. A projector may include light source  19 , filter wheel  17 , and micro mirror device  20 . Micro mirror device  20  may be in the form of a chip and may be attached to board  21 . Filter wheel  17  (an example of a variable filter) may be for varying the wavelength of the light output from light source  19  into different spectrums of ultraviolet light. For example rotation of filter wheel  17  may vary the wavelength of light that is allowed to pass through filter wheel  17 . Micro mirror device  20  may receive light output from filter wheel  17  and reflect the light onto screen  23 .The selective reflection of light from micro mirror device  20  and the position in rotation of filter wheel  17  may be calibrated so that images with predetermined characteristics can be displayed. 
       FIG. 6  is an example illustration of projector components which includes a prism, in accordance with embodiments.  FIG. 7  is a different view of the projector components illustrated in  FIG. 6 . A projector may include light source  25 , filter wheel  27 , light pipe  29 , lens  30 , mirror  31 , lens  32 , prism  33 , micro mirror device  35 , and/or lens  37 , which may be configured to manipulate ultraviolet light. 
     Filter wheel  27  may be for varying the wavelength of the light output from light source  25  in the ultraviolet spectrum. Filter wheel  27  may rotate to vary the wavelength of light that is allowed to pass through filter wheel  27 . Micro mirror device  35  may receive light output from filter wheel  27  and reflect the light onto screen  38 . The selective reflection of light from micro mirror device  35  and the position in rotation of filter wheel  27  may be calibrated so that images with predetermined characteristics can be displayed. Light pipe  29  may receive light from filter wheel  27  and spatially redistribute the light at a substantially uniform intensity. In embodiments, light pipe  29  is designed to reflect ultraviolet light, so that incident ultraviolet light is spatially redistributed at a substantially uniform intensity. Lens  30  may be for focusing light output from light pipe  29  to reduce the diameter of the light. In embodiments, lens  30  is configured to collect ultraviolet light. Mirror  31  may be for reflecting light output from lens  30  at an angle. Lens  32  may be for focusing light output from mirror  31 . In embodiments, lens  30  and lens  32  are configured to focus ultraviolet light. Prism  33  may receive light output from lens  32  and transmit the light in a direction according to angles of mirrors of micro mirror device  35 , in accordance with control signals input into micro mirror device  35 . In embodiments, prism  33  is configured to transmit ultraviolet light. 
     In  FIG. 4 through 7 , micro mirror device  13 , micro mirror device  20 , and micro mirror device  35  are examples of projection modulators. However, other types of projection modulators can be appreciated. Arrangement, inclusion, and/or exclusion of components which have functional relationships with a projection modulator can be appreciated. In embodiments, a projection modulator can be configured to modulate ultraviolet light. 
     In  FIGS. 4 through 7 , filter wheel  17  and filter wheel  27  are examples of variable light filters. However, other types of variable light filters can be appreciated. Arrangement, inclusion, and/or exclusion of components which have functional relationships with a variable light filter can be appreciated. In embodiments, a variable light filter can be configured to pass different spectrums of ultraviolet light. 
     In  FIGS. 6 and 7 , light pipe  29  is an example of a light integrator. However, other types of light integrators can be appreciated. Arrangement, inclusion, and/or exclusion of components which have functional relationships with a light integrator can be appreciated. In embodiments, a light integrator can be configured to spatially redistribute ultraviolet light substantially uniformly. In embodiments, a light integrator may include an ultraviolet transparent material (e.g. material which transmits light having a wavelength less than 500 nanometers). Example ultraviolet transparent materials are fused silica, calcium fluoride, magnesium fluoride, sapphire, barium fluoride, beryllium oxide, calcite, and/or germanium oxide. 
       FIGS. 8 through 11  illustrate examples of different variable filters.  FIG. 8  illustrates variable light filter  214  with a first region  210  and a second region  212 . Variable light filter  214  may be a filter wheel. First region  210  and second region  212  may be filters that pass different ranges of excitation light. 
       FIG. 9  illustrates variable light filter  216  with four regions (regions  224 ,  222 ,  218 , and  220 ). Any number of regions could be implemented in accordance with embodiments. 
       FIG. 10  illustrates variable light filter  226  with three regions (regions  232 ,  230 , and  228 ). As illustrated in  FIG. 10 , the different regions can be distributed non-uniformly. As illustrated in  FIGS. 8 and 9 , the different regions can be distributed uniformly. Regions may be distributed non-uniformly to compensate differences in visible light emission of light emitting materials. 
       FIG. 11  illustrates variable light filter  234  with four regions (regions  242 ,  240 ,  238 , and  236 ) distributed in a spiral pattern. A variable light filter with a spiral pattern may increase efficiency of a projector by reusing back reflected light. As illustrated in  FIGS. 8 through 10 , regions of a variable light filter may be distributed in a radial direction. Other distributions of light filter regions can be appreciated. 
     Embodiments relate to an apparatus including a light source, a projection modulator, and a variable light filter. The projection modulator is configured to modulate light emitted from the light source. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light include light with a wavelength less than 500 nanometers. The at least two different wavelength ranges of light may include light with a wavelength less than 450 nanometers. The at least two different wavelength ranges of light may include light with a wavelength less than 420 nanometers. The light transmitted through the light source may be projected onto a substantially transparent substrate. Fluorescent particles may be integrated into the substantially transparent substrate. Fluorescent particles may emit visible light in response to absorption of light emitted from the light source. Each of the fluorescent particles may have a diameter less than 500 nanometers. The at least two different wavelength ranges of light may include ultraviolet light. The at least two different wavelength ranges of light may consist of ultraviolet light. The projection modulator may include an array of modulators. Each modulator of the array of modulators may be a movable mirror. The projection modulator may be a micro mirror device. The micro mirror device may be an analog micro mirror device. The micro mirror device may be a digital micro mirror device. The micro mirror device may be configured to modulate light having a wavelength less than 500 nanometers. The variable light filter may be configured to transmit light prior to the light being modulated by the projection modulator. The variable light filter may include a disk with at least two different types of light filters. The variable light filter may be configured to selectively transmit the at two different wavelength ranges of light by selectively rotating the disk to control which of the at least two different types of light filters is in a path of light emitted from the light source. The at least two different types of light filters may be substantially evenly distributed on the disk. The at least two different types of light filters may be non-uniformly distributed on the disk. The at least two different types of light filters may be distributed on the disk in a radial direction. The at least two different types of light filters may be distributed on the disk in a spiral pattern. At least one lens may be configured to focus light having a wavelength less than 500 nanometers. A light integrator may be configured to redistribute light having a wavelength less than 500 nanometers. The light integrator may include an ultraviolet transparent material and an anti-reflective coating for light having a wavelength less than 500 nanometers. The ultraviolet transparent material may include fused silica, calcium fluoride, magnesium fluoride, sapphire, barium fluoride, beryllium oxide, calcite, and/or germanium oxide. The light source may include a reflector. The reflector may have a reflective enhancement coating for light having a wavelength less than 500 nanometers. The light source may include an ultraviolet lamp. The ultraviolet lamp may be one of a gas discharge lamp, a solid state lamp, a light emitting diode lamp, and a metal halide lamp. A visible light filter may be configured to substantially remove visible light emitted from the light source prior to light from the light source being modulated by the projection modulator. A light separator may be configured to separate light having a wavelength less than 500 nanometers. 
     Embodiments relate to a method including emitting light from a light source, modulating the light at a projection modulator, and filtering the light at a variable light filter. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light include light with a wavelength less than 500 nanometers. 
     Embodiments relate to a method including integrating a light source, a projection modulator, and a variable light filter into a projector. The projection modulator is configured modulate light emitted from the light source. The variable light filter is configured to selectively transmit at least two different wavelength ranges of light. The at least two different wavelength ranges of light comprise light with a wavelength less than 500 nanometers. 
     The foregoing embodiments (e.g. light emitting material integrated into a substantially transparent substrate) and advantages are merely examples and are not to be construed as limiting the appended claims. The above teachings can be applied to other apparatuses and methods, as would be appreciated by one of ordinary skill in the art. Many alternatives, modifications, and variations will be apparent to those skilled in the art.