Abstract:
There is provided a system and method for providing touchscreen functionality in a digital light processing system. More specifically, in one embodiment, there is provided a method, comprising assigning each of a plurality of micromirrors ( 17 ) on a digital micromirror device ( 18 ) a unique identifier, projecting light toward at least one of the plurality of micromirrors ( 17   a ), and actuating the at least one micromirror ( 17   a ) in a pattern corresponding to its identifier.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Chinese (CN) National Patent Application No. CN 200610103952.1 filed on Jul. 28, 2006, which is incorporated by reference as though completely set forth herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to projecting video images onto a screen. More specifically, the present invention relates to providing touchscreen functionality in a Digital Light Processing (“DLP”) video unit. 
       BACKGROUND OF THE INVENTION 
       [0003]    This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
         [0004]    Digital Light Processing (“DLP”) is a display technology that employs an optical semiconductor, known as a Digital Micromirror Device (“DMD”) to project video onto a screen. DMDs typically contain an array of hundreds of thousands or more microscopic mirrors mounted on microscopic hinges. Each of these mirrors is associated with at least one point on the screen, known as a pixel. By varying the amount of light that is reflected off each of these mirrors, it is possible to project video onto the screen. Specifically, by electrically actuating each of these hinge-mounted microscopic mirrors, it is possible to either illuminate a point on the screen (i.e., “turn on” a particular micromirror) or to leave that particular point dark by reflecting the light somewhere else besides the screen (i.e., “turn off” the micromirror). Further, by varying the amount of time a particular micromirror is turned on, it is possible to create a variety of gray shades. For example, if a micromirror is turned on for longer than it is turned off, the pixel that is associated with that particular micromirror will have a light gray color; whereas if a particular micromirror is turned off more frequently than it is turned on, that particular pixel will have a darker gray color. In this manner, video can be created by turning each micromirror on or off several thousand times per second. Moreover, by sequentially shining red, green, and blue at the micromirrors instead of white light, it is possible to generate millions of shades of color instead of shades of gray. 
         [0005]    As most people as aware, touchscreen displays are a growing trend in modern display units and computers. Unlike traditional interfaces, such as a keyboard, mouse, remote control, and the like, touchscreens enable a user to directly interact with the screen of a display. Advantageously, touchscreen systems are typically more intuitive to control than traditional display technologies (e.g., selections are made by simply pointing at the desired item on the screen). Moreover, beyond control, many touchscreens enable users to write on the screen—in much the same way that one would write on a piece of paper. Amongst other uses, this functionality may enable the display to be used as a digital “chalkboard” or to be used as a canvas for illustrators or artists. As mentioned above, the touchscreen interface is typically more intuitive to use than conventional devices that provide this functionality (e.g., graphic tablet computers and the like). 
         [0006]    Unfortunately, conventional systems for providing touchscreen functionality are typically expensive and/or provide relative low resolution. For example, many conventional touchscreen systems employ a grid of capacitors and/or resistors that are configured to detect physical contact with the screen. Disadvantageously, the detection grid must be precisely assigned with the display screen during assembly of the video unit. This increases the assembly cost for the video unit. Moreover, the resolution of this type of touchscreen system is based on the resolution of the detection grid not on the display resolution of the video unit itself. As such, the resolution of the touchscreen grid is typically much lower than the resolution of the display. Other conventional touchscreen technologies, such as surface acoustic wave systems, near field imaging systems, and infrared system have similar disadvantages. An improved system and method for providing touchscreen functionality in a DLP video unit is desirable. 
       SUMMARY OF THE INVENTION 
       [0007]    Certain aspects commensurate in scope with the disclosed embodiments are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. 
         [0008]    There is provided a system and method for providing touchscreen functionality in a digital light processing system. More specifically, in one embodiment, there is provided a method, comprising assigning each of a plurality of micromirrors on a digital micromirror device a unique identifier, projecting light toward at least one of the plurality of micromirrors, and actuating the at least one micromirror in a pattern corresponding to its identifier. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Advantages of the invention may become apparent upon reading the following detailed description and upon reference to the drawings in which: 
           [0010]      FIG. 1  is a block diagram of a digital light processing touchscreen video unit in accordance with an exemplary embodiment of the present invention; 
           [0011]      FIG. 2  is a diagram of a color wheel in accordance with an exemplary embodiment of the present invention; and 
           [0012]      FIG. 3  is a flow chart illustrating an exemplary technique for enabling touchscreen functionality in a digital light processing video unit in accordance with an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0014]    Turning initially to  FIG. 1 , a block diagram of a DLP touchscreen video unit in accordance with an exemplary embodiment of the present invention is illustrated and generally designated by a reference numeral  10 . In one embodiment, the video unit  10  may comprise a DLP projection television. In another embodiment, the video unit  10  may comprise a DLP-based video or movie projector. In still other embodiments, the video unit may comprise other suitable DLP-based systems—or the like. 
         [0015]    The video unit  10  may include a light source  12 . The light source  12  may include any suitable form of lamp or bulb capable of projecting white or generally white light  28 . In one embodiment, the light source  12  may include a metal halide, mercury vapor, or ultra high performance (“UHP”) lamp. In alternate embodiments, the light source  12  may include one or more light emitting diodes (either white or colored). In one embodiment, the light source  12  is configured to project, shine, or focus the white light  28  into one static location as described further below. 
         [0016]    As illustrated in  FIG. 1 , the exemplary video unit  10  also comprises a color wheel  14  aligned in an optical line of sight with the light source  12 .  FIG. 2  is a diagram of the color wheel  14  in accordance with an exemplary embodiment of the present invention. The color wheel  14  may comprise a variety of color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  arrayed as arcuate regions on the color wheel  14 . Specifically, in the illustrated embodiment, the color wheel  14  comprises color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  configured to convert the white light  28  into one of the three primary colors of light: red, green, or blue. In particular, the illustrated embodiment of the color wheel  14  comprises two red color filters  40   a  and  40   b , two green color filters  42   a  and  42   b , and two blue color filters  44   a  and  44   b.    
         [0017]    It will be appreciated that in alternate embodiments, the specific colors of the filters  40   a ,  40   a ,  42   a ,  42   b ,  44   a , and  44   b  may be altered or the number of filters may be altered. For example, in one alternate embodiment, the color wheel  14  may comprise only one red color filter  40   a , one green color filter  42   b , and one blue color filter  44   a . In this embodiment, the arcuate regions occupied by the color filters  44   a ,  44   b , and  44   c  may be approximately twice as long (as measured along the circumference of the color wheel  14 ) than the color filters  40   a ,  42   b , and  44   a  depicted in  FIG. 2 . In still other embodiments, the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  may occupy either more or less of the surface area of the color wheel depending on the configuration and function of the video unit  10 . 
         [0018]    In addition, as illustrated in  FIG. 2 , each of the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  may include a sub-sector  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b , respectively. As will be described in greater detail below with regard to  FIG. 3 , in one embodiment, the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  enable the video unit  10  to provide touchscreen functionality. In one embodiment, the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  occupy approximately ten percent of each of the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b . It will be appreciated, however, that the size and location of each of the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  illustrated in  FIG. 2  is merely exemplary. As such, in alternate embodiments, the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  maybe vary in size and location within the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b . Moreover, it will be understood that the sub-sectors may be a logical sub-section of the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  (i.e., the sub-sectors  46   a ,  46 ,  48   a ,  48   b ,  50   a , and  50   b  may not be separated from the color filter by any visible or physical divider). 
         [0019]    Turning next to the operation of the color wheel  14 , each of the filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  is designed to convert the white light  28  generated by the light source  12  into colored light  30 . In particular, the color wheel  14  may be configured to rapidly spin in a counterclockwise direction  51  around its center point  52 . In one embodiment, the color wheel  14  rotates  60  times per second. As described above, the light source  12  may be configured to focus the white light  28  at the color wheel  14 . On the opposite side of the color wheel from the light source  12 , there may be an integrator  15 , which is also referred to as a light tunnel. In one embodiment, the integrator  15  is configured to the evenly spread the colored light  30  across the surface of a DMD  18 . As such, those skilled in the art will appreciate that most, and possibly all, of the light that will be reflected off the DMD  18  to create video will pass through the integrator  15 . 
         [0020]    Because the integrator  15  is fixed and the color wheel  14  rotates, the light that will enter the integrator  15  can be illustrated as a fixed area  54  that rotates around the color wheel  14  in the opposite direction from the color wheel&#39;s direction of rotation. For example, as the color wheel  14  rotates in the counterclockwise direction  51 , the fixed area  54  rotates through each the filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b  in the clockwise direction  53 . As such, those skilled in the art will recognize that the colored light  30  entering the integrator  15  will rapidly change from red to green to blue to red to green to blue with each rotation of the color wheel  14  as the fixed area  54  passes through each of the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b . In other words, because the light source  12  is stationary, the counterclockwise rotation of the color wheel  14  causes the fixed area  54  to rotate in a clockwise direction  53  through the colors of the color wheel. In alternate embodiments, the color wheel  14  itself may rotate in the clockwise direction  53 . Those of ordinary skill in the art will appreciate that the size and shape of the fixed area  54  is merely illustrative. In alternate embodiments, the size and shape of the fixed area  54  may be different depending on the optical design of the system. 
         [0021]    Returning now to  FIG. 1 , the video unit  10  may also comprise a DLP circuit board  16  arrayed within an optical line of sight of the integrator. The DLP circuit board  16  may comprise the DMD  18  and a processor  20 . As described above, the DMD  18  may include a multitude of micromirrors  17   a ,  17   b , and  17   c , for example, mounted on microscopic, electrically-actuated hinges that enable the micromirrors  17  to tilt between a turned on position and turned off position. 
         [0022]    The colored light  30  that reflects off a turned on micromirror (identified by a reference numeral  34 ) is reflected to a projecting lens assembly  24  and then projected on to a screen  28  for viewing. On the other hand, the colored light that reflects off of a turned off micromirror (identified by a reference numeral  32 ) is directed somewhere else in the video besides the screen  28 , such as a light absorber  22 . In this way, the pixel on the screen  28  that corresponds to a turned off micromirror does not receive the projected colored light  30  while the micromirror is turned off. 
         [0023]    The DMD  18  may also be coupled to the processor  20 . In one embodiment, the processor  20  may receive a video input and direct the micromirrors  17  on the DMD  18  to turn on or off, as appropriate, to create a video image. In addition, as described in greater detail below, the processor  20  may also be configured to direct the micromirrors  17  on the DMD  18  to turn on or off, as appropriate, to project a unique light pattern that may be used to identify pixel locations corresponding to each individual micromirror  17 . It will be appreciated, however, that, in alternate embodiments, the processor  20  may be located elsewhere in the video unit  10 . 
         [0024]    As illustrated in  FIG. 1 , the video unit  10  may also include a light pen  26 . As will be described in greater detail below, the light pen  26  may enable touchscreen functionality in the video unit  10 . More specifically, when the light pen  26  touches a pixel location the screen  28 , it may be configured to receive the unique light pattern projected at that pixel location. As such, in one embodiment, the light pen  26  may include one or more photodiodes that are configured to receive light and convert it into an electrical signal. However, in other embodiments, other suitable light reception and detection devices may be employed. 
         [0025]    The light pen  26  may then be configured to transmit the unique light pattern to the processor  20  or another suitable computational unit within the video unit  10 . In this illustrated embodiment, the connection between the light pen  26  and the processor is via a wire or cable. In alternate embodiments, however, this connection may be a wireless connection. When the processor  20  receives the unique light pattern, it can identify the micromirror  17  that projected the unique light pattern and, in turn, identify the pixel location where the light pen  26  touched the screen  28 . The location of this “touch” can then be transmitted to the DMD  18  to enable “writing” on the screen  28 , used to indicate a selection to a computer, or employed for another suitable touchscreen application. 
         [0026]      FIG. 3  is a flow chart illustrating an exemplary technique  60  for enabling touchscreen functionality in a digital light processing video unit in accordance with embodiments of the present invention. In one embodiment, the technique  60  may be performed by the video unit  10 . In alternate embodiments, however, other suitable types of video units, displays, computers, and so forth may execute the technique  60 . 
         [0027]    As indicated in block  62 , the technique  60  may begin by assigning each of the micromirrors  17  on the DMD  18  a unique identifier. For example, the micromirrors  17  may be assigned a row and column identifier representative of each micromirror&#39;s location on DMD  18 . Alternatively, each of the micromirrors  17  may be assigned an individual numeric or alphanumeric identifier. For example, each of the micromirrors may be assigned a sequential number. In still other embodiments, other suitable identification schemes may be used to assign a unique identifier to each of the micromirrors  17 . 
         [0028]    Next, the light source  12  may be configured to project light at the micromirrors  17 , as indicated in block  64 . As illustrated in  FIG. 1 , in one embodiment, the light source  12  may project white light  28  through the rotating color wheel  14 . After the light source  12  begins projecting light, the DMD  18  may actuate each of the micromirrors  17  in a pattern associated with the unique identifier associated with that particular micromirror  17 , as indicated in block  66 . For example, if the unique identifier associated with the micromirror  17   a  is column  517  and row  845 , the micromirror  17   a  may be configured to actuate in such a way to communicate the unique identifier. More specifically, the micromirror  17   a  may be configured transmit the bit sequence  1000000101  ( 517  in binary) then the bit sequence  1101001101  ( 845  in binary), where the 1&#39;s correspond to the micromirror  17  in the on position and the 0&#39;s correspond the off position. Similarly, if the unique identifier associated with the micromirror  17   b  is column  518  and row  845 , the micromirror  17   b  may be configured to transmit the bit sequence  1000000110  ( 518  in binary) then the bit sequence  1101001101  ( 845  in binary). 
         [0029]    As described above, however, the micromirrors  17  are also configured to turn on and off, as appropriate, to project video images onto the screen  28 . As such, micromirrors  17  may be configured to divide their time between projecting video images and projecting their unique identifier. For example, in the embodiment illustrated in  FIG. 1 , the micromirrors  17  may be configured to project the bit sequences associated with their individual unique identifier when the fixed area  54  is passing through the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  and to project video images when the fixed area is passing through the remainder of the color filters  40   a ,  40   b ,  42   a ,  42   b ,  44   a , and  44   b . Moreover, in non-color wheel embodiments, the video unit may be configured to designate a certain percentage (e.g., ten percent) of each color to project the bit sequences. 
         [0030]    For example, in one embodiment, the micromirrors  17  may be configured to project two bits during each of the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  for a total of twelve bits per rotation of the color wheel  14 . In this embodiment, every odd rotation of the color wheel  14  may be used to project the bit sequence for the row component of the unique identifier and every even rotation of the color wheel  14  may be used to project bit sequence for the column component of the unique identifier. Accordingly, an array of 4096 (the largest number possible with twelve bits) by 4096 unique row and column micromirror addresses can be coded. Further, in alternate embodiments, other suitable coding schemes can be employed. For example, in one embodiment, only one bit may be projected during each of the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b  and more rotations of the color wheel  14  may used to compile each bit sequence (e.g., two rotations for the column bit sequence and two rotations for the row bit sequence). Furthermore, in still other embodiments, other suitable coding techniques may be used. 
         [0031]    Returning now to  FIG. 3 , as the light  30  reflects off the micromirrors  17 , the bit sequences for each of the micromirrors  17  will be displayed as light patterns at the pixel locations on the screen  28  that correspond to each of the micromirrors  17  (block  68 ). The light pen  26  may then be configured to detect these light patterns, as indicated by block  72 . As described above, the light pen  26  may include one or more photodiodes that are configured to convert the light patterns into a digital signal. In addition, in one embodiment, the light pen  26  may also include an activation switch or button that enables a user to choose whether touching the light pen  26  to screen will trigger the touchscreen functionality. 
         [0032]    Once the light pen  26  has received the light pattern, the light pattern may be converted back into the unique identifier, as indicated by block  72 . In one embodiment, the light pen  26  may be synchronized with the color wheel  14  and, thus, configured to know when the light being projected at the screen  28  is part of the identifier as opposed to being part of the video image. As such, the light pen  26  may be configured to isolate the sections of the digital signal (e.g., binary bits) that correspond to light that was projected during the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b . Once these sections are isolated, their bits may be combined together to form the above-described bit sequences that can be converted into the unique identifier for one of the micromirrors  17 . Alternatively, the light pen  26  may be configured to transmit the bits for the entire rotation of the color wheel  14  to the processor  20  or other suitable computational device. The processor  20  may then be configured isolate the bits that occurred during the sub-sectors  46   a ,  46   b ,  48   a ,  48   b ,  50   a , and  50   b.    
         [0033]    Next, the processor  20  (or other suitable computational device) will identify the micromirror  17  associated with the unique identifier, as indicated in block  74 . In one embodiment, identifying the micromirror  17  may involve determining which micromirror was assigned the particular unique identifier in block  62  above. 
         [0034]    After the micromirror  17  associated with the unique identifier has been identified, the pixel location on the screen  28  that corresponds to that micromirror  17  may be designated as “touched,” as indicated by block  76 . In one embodiment, the color of the video image may be altered in the touched location. For example, all of the pixel locations touched by the light pen  26  may be changed to black, white, or another suitable color. In this way, the video unit  10  enables a user to write on the screen. Moreover, because the resolution of the light pen  26  is the same as the display resolution of the video unit  10 , the light pen  26  enables writing on the screen at resolutions far in excess of conventional graphics tablets at considerably less cost. 
         [0035]    In another embodiment, the touched pixel location may be transmitted to a computer or other electronic device (not shown) that is using the video unit  10  as a display. In this way, the light pen  26  may be used to select or choose items or icons shown on the screen  28  to replace or supplement a mouse, keyboard, or other control device. Alternatively, this embodiment may also be employed in conjunction with handwriting recognition systems to allow users to write text or images directly into files or documents. 
         [0036]    As described above, the pixel location on the screen  28  that corresponds to the micromirror  17  may be designated as “touched.” It will be appreciated, however, that in embodiments of the video unit  10  employing Smooth Picture™ technology (i.e., including a modulator that shifts light from one micromirror  17  to a plurality of pixel locations), the position of the modulator may also be considered when determining the pixel location corresponding to the micromirror  17 . In other words, before designating a pixel location as touched, the video unit  10  will determine both the micromirror  17  and the position of the modulator as the one micromirror  17  may provide light for a plurality of pixel locations. 
         [0037]    As described above, the video unit  10  provides DLP touchscreen functionality with high resolution at a relatively low cost. Advantageously, the video unit  10  requires no modification to the conventional DLP optical path or light engine structure and requires no special screen. As such, the video unit  10  can provide enhanced touchscreen functionality for only a slightly higher cost than conventional DLP systems. 
         [0038]    While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.