Patent Publication Number: US-2010110024-A1

Title: Method for providing user interface using dmd and dlp display apparatus using the method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Korean Patent Application No. 10-2008-0107108, filed on Oct. 30, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Apparatuses and methods consistent with the present invention relate to a method for providing a user interface, and a Digital Light Processing (DLP) display apparatus using the method, and more particularly, to a method for providing a user interface for a DLP display apparatus to receive a user command using touch by a user, and the DLP display apparatus using the method. 
     2. Description of the Related Art 
     Digital Light Processing (DLP) televisions, called the third generation of projection televisions, use a semiconductor chip, consisting of more than 1.3 millions of mirrors that can be separately controlled, known as a Digital Micro-mirror Device (DMD). 
     In DLP televisions, an image is created on a screen by passing a light beam emitted from a lamp through a color wheel coated with an RGB filter, which generates the RGB primary colors, reflecting the RGB primary colors from each pixel of a DMD. 
     In DLP televisions, it is easy to enlarge a screen, and the cost for enlarging a screen is low. Accordingly, DLP televisions are generally used for presentations. In order to better use DLP televisions in presentation, a touchscreen function is needed. 
     However, in order to add the touchscreen function to DLP televisions, a device for recognizing a user&#39;s touch is additionally required, thereby increasing the television&#39;s price. In addition, if a separate device for recognizing the user&#39;s touch is installed, an optic axis of light displayed on the screen and an optic axis of light used to recognize touch do not coincide, so calibration between the DLP television and the device for recognizing the user&#39;s touch is required. 
     As described above, the device for recognizing touch on the DLP television requires additional components and additional costs. Therefore, there is a demand for more easily providing a user interface. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present invention address at least the above problems and/or disadvantages, and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an exemplary embodiment of the present invention may not overcome any of the problems described above. 
     An aspect of the present invention provides a method for providing a user interface, by which a Digital Micro-mirror Device (DMD) reflects light emitted from a light source to a screen and an image sensor detects the light reflected from the DMD, and a digital light processing (DLP) display apparatus using the method, so as to more conveniently provide a user interface for the DLP display apparatus. 
     According to an exemplary aspect of the present invention, there is provided a Digital Light Processing (DLP) display apparatus including a light source which projects light on a screen, a Digital Micro-mirror Device (DMD) which includes a plurality of micro-mirrors, and if the light projected from the light source is diffused on the screen, the DMD reflects the diffused light, and an image sensor which detects the light reflected from the DMD. 
     The image sensor may detect light reflected from at least one micro-mirror which is turned off in the DMD. 
     The DMD may turn off all of the micro-mirrors in the DMD for a certain period among periods corresponding to a single frame. 
     The light source may project the light for total reflection in the screen, and the total-reflected light may be diffused on an area touched by a user on the screen. 
     The DLP display apparatus may further include a control unit which determines the touched area on the screen using information detected by the image sensor. 
     The light source may use an infrared ray. 
     The light source may externally project the light onto a surface of the screen, and the projected light may be diffused on the surface of the screen. 
     The DLP display apparatus may further include a control unit which determines an area onto which the light is projected on the screen using information detected by the image sensor. 
     The light source may use a visible ray. 
     According to another exemplary aspect of the present invention, there is provided a method for providing a user interface for a Digital Light Processing (DLP) display apparatus, the method including projecting light on a screen, at a Digital Micro-mirror Device (DMD), if the projected light is diffused on the screen, reflecting the diffused light, and at an image sensor, detecting the light reflected from the DMD. 
     In the detecting operation, light reflected from at least one micro-mirror which is turned off in the DMD may be detected. 
     The method may further include at the DMD, turning off all of the micro-mirrors in the DMD for a certain period among periods corresponding to a single frame. 
     In the projecting operation, the light may be projected for total reflection in the screen, and the total-reflected light may be diffused on an area touched by a user on the screen. 
     The method may further include determining the touched area on the screen using information detected by the image sensor. 
     The light projected for total reflection in the screen may be an infrared ray. 
     In the projecting operation, the light may be externally projected onto a surface of the screen, and the projected light may be diffused on the surface of the screen. 
     The method may further include determining an area onto which the light is projected on the screen using information detected by the image sensor. 
     The externally projected light may be a visible ray. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which: 
         FIG. 1  is a block diagram illustrating a detailed configuration of a Digital Light Processing (DLP) display apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a flow chart illustrating a method for providing a user interface for a DLP display apparatus capable of recognizing a user&#39;s touch according to an exemplary embodiment of the present invention; 
         FIG. 3  is a flow chart illustrating a method for providing a user interface for a DLP display apparatus capable of recognizing light projected to a screen according to another exemplary embodiment of the present invention; 
         FIG. 4  illustrates a process of reflecting light of a display lamp from a DMD to a screen and displaying an image on the screen in a DLP display apparatus according to an exemplary embodiment of the present invention; 
         FIG. 5  illustrates a user touching a second area on the screen according to an exemplary embodiment of the present invention; 
         FIG. 6  illustrates a user touching a first area on the screen according to an exemplary embodiment of the present invention; 
         FIG. 7  illustrates light projected from a light source to a second area on the screen according to an exemplary embodiment of the present invention; and 
         FIG. 8  illustrates light projected from a light source to a first area on the screen according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION 
     Certain exemplary embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings. 
     In the following description, like drawing reference numerals are used for like elements, even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the invention. However, the present invention can be practiced without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the invention with unnecessary detail. 
       FIG. 1  is a block diagram illustrating a detailed configuration of a Digital Light Processing (DLP) display apparatus according to an exemplary embodiment of the present invention. As illustrated in  FIG. 1 , the DLP display apparatus may include an image input unit  110 , a storage unit  120 , an image processing unit  140 , a display lamp  410 , a color wheel  420 , a color wheel sensor  423 , a motor driving unit  426 , a Digital Micro-mirror Device (DMD)  430 , a light absorbing unit  440 , a screen  450 , an image sensor  460 , a light source  470 , and a control unit  480 . 
     The image input unit  110  receives image information from an external device (not shown). The image input unit  110  may include input terminals corresponding to the standards of D-sub, Digital Visual Interface (DVI), and High-Definition Multimedia Interface (HDMI). 
     The storage unit  120  stores image data, and transmits the image data to the image processing unit  140 . 
     The image processing unit  140  performs signal-processing, such as video decoding and video scaling, for an image signal which is input from the image input unit  110  or received from the storage unit  120 . Subsequently, the image processing unit  140  converts the image signal into image data of a format for driving the DMD  430 , and transmits the image data to the DMD  430 . 
     The display lamp  410  emits a light beam using supplied power, and irradiates the light beam to the DMD  430  through the color wheel  420 . 
     The color wheel  420  filters the light beam emitted from the display lamp  410  and thus outputs the RGB primary colors: red, green, and blue. The color wheel  420  rotates at a certain speed and sequentially irradiates red, green, and blue light to the DMD  430  at certain time intervals. 
     The color wheel sensor  423  examines the rotational state of the color wheel  420  which is currently operating. That is, if the color wheel sensor  423  provides the control unit  480  with information regarding the rotational state of the color wheel  420 , the control unit  480  senses and controls the phase and rotational speed of the color wheel  420  using the information. 
     The motor driving unit  426  drives a motor which is connected to the color wheel  420 . 
     The DMD  430  may include approximately 1.3 million micro-mirrors. The DMD  430  determines whether to turn each micro-mirror on or off according to the image data received from the image processing unit  140 . The DMD  430  selectively reflects light irradiated from the display lamp  410  using each micro-mirror so that an image can be created on the screen  450 . That is, the DMD  430  controls the RGB color light reflected from the micro-mirrors of the DMD  430  based on the image data received from the image processing unit  140 , thereby creating an image to be displayed on the screen  450 . 
     In addition, if light emitted from the light source  470  is diffused on the screen  450 , the DMD  430  reflects the diffused light to the image sensor  460 . The light source  470  is a light source which is separately added to provide a user interface, and a detailed description of the light source  470  will be given later. 
     The DMD  430  may turn off the micro-mirrors for a certain time from among the periods corresponding to a single frame. This is because if the micro-mirrors in the DMD  430  are turned on, the image sensor  460  cannot detect light. Accordingly, if the micro-mirrors in the DMD  430  are turned off for a certain period, the image sensor  460  can detect light of the light source  470  diffused on the screen  450  for the certain period. For example, if there are a total of 256 levels to express the brightness of a frame, the DMD  430  reduces the levels to express the brightness to be 240, and turns off the micro-mirrors in the DMD  430  for a period corresponding to the 16 remaining levels. 
     As described above, if the DMD  430  turns off the micro-mirrors for a certain period from among the periods corresponding to a single frame, touch by the user on the screen  450  can also be recognized during the period. 
     The light absorbing unit  440  absorbs light, which is reflected from a micro-mirror in the DMD  430 , when the micro-mirror is turned off Accordingly, if a micro-mirror in the DMD  430  is turned off, light is not projected to an area of the screen  450  corresponding to the micro-mirror. 
     The screen  450  receives light reflected from the DMD  430 , from among light emitted from the display lamp  410 , and displays an image. More specifically, only light reflected from a micro-mirror which is turned on from among the micro-mirrors in the DMD  430  is projected on the screen  450  so as to express an image. 
     The image sensor  460  detects light reflected from DMD  430 . More specifically, if light emitted from the light source  470  is diffused on the screen  450  and is reflected from the DMD  430 , the image sensor  460  detects the light reflected from the DMD  430 . In particular, the image sensor  460  detects light reflected from at least one micro-mirror which is turned off in the DMD  430 . Accordingly, the image sensor  460  is disposed on an optical path of light reflected from the micro-mirror in the DMD  430  which is turned off. 
     The image sensor  460  detects image information regarding the entire screen  450 . If light is diffused on the screen  450 , a pixel corresponding to a diffused area of the screen  450  from among the pixels of the image sensor  460  detects the diffused light. 
     Therefore, information detected by the image sensor  460  may be image information in which only the diffused area is expressed brightly on the entire screen  450 . That is, information detected by the image sensor  460  is image information indicating whether or not light is diffused for the entire screen  450 . Since the diffused area of the screen  450  may be an area touched by the user, or an area on which the light source  470  projects light, the control unit  480  can determine the touched area or the projected area using the information detected by the image sensor  460 . 
     The image sensor  460  may be implemented as a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor. 
     As described above, since the image sensor  460  detects light diffused on the screen  450 , a touched area of the screen  450  or an area of the screen  450  on which the light source  470  projects light can be detected. 
     The light source  470  projects light on the screen  450 . More specifically, the light source  470  may project light for total reflection in the screen  450 , or may externally project light onto the surface of the screen  450 . 
     If the light source  470  projects light for total reflection in the screen  450 , the light is diffused on a touched area of the screen  450 , and the diffused light is reflected by the DMD  430  and detected by the image sensor  460 . The control unit  480  determines the touched area of the screen  450  using information detected by the image sensor  460 . 
     In this case, the light source  470  may use an infrared ray. This is because, although an infrared ray is diffused on the screen  450 , the infrared ray cannot be viewed by the user. In addition, because of using the infrared ray, touch by a pen or a touch pen as well as by the user&#39;s hand can be recognized. 
     A detailed description of when the light source  470  projects light for total reflection in the screen  450  will be given later with reference to  FIGS. 5 and 6 . 
     As described above, the DLP display apparatus can perform a touchscreen function simply by having the image sensor  460  and the light source  470 . In this case, since an optic axis of light of the light source  470  is the same as an optic axis of light of the display lamp  410 , distortion between a displayed image and a touched area can be minimized, and calibration between coordinates of the image and coordinates of the touch area can be minimized. In addition, since only the image sensor  460  and the light source  470  are added to the DLP display apparatus, the touchscreen function can be implemented with a low cost. 
     Alternatively, if the light source  470  externally projects light onto the surface of the screen  450 , the light is diffused on the surface of the screen  450 . The diffused light is reflected by the DMD  430 , and detected by the image sensor  460 . Subsequently, the control unit determines the projected area on the screen  450  on which the light source  470  projects the light using information detected by the image sensor  460 . 
     In this case, the light source  470  may use a visible ray. For example, the light source  470  may be a laser pointer. More specifically, in a presentation, if a laser pointer projects a ray onto the screen  450  of the DLP display apparatus, the DLP display apparatus detects the projected area on the screen  450 . Hereinafter, a “light source recognition function” refers to a function for the DLP display apparatus recognizing an area on which the light source  470  is projected on the screen  450 . 
     A detailed description of when the light source  470  externally projects light onto the surface of the screen  450  will be given later with reference to  FIGS. 7 and 8 . 
     As described above, the DLP display apparatus can perform the light source (for example, a laser pointer) recognition function simply by having the image sensor  460  and the light source  470 . In this case, since an optic axis of light of the light source  470  is the same as an optic axis of light of the display lamp  410 , distortion between a displayed image and an area on which light of the light source  470  is projected on the screen  450  can be minimized, and calibration between coordinates of the image and coordinates of the projected area on the screen  450  can be minimized. In addition, since only the image sensor  460  and the light source  470  are added to the DLP display apparatus, the light source recognition function can be implemented with a low cost. 
     The control unit  480  controls the DLP display apparatus. If a user command is input using a manipulation button or a remote control, the control unit  480  outputs a control signal so as to perform the operation in response to the user&#39;s command. 
     In particular, the control unit  480  determines a touched area of the screen  450  or an area on which light of the light source  470  is projected on the screen  450 , using information detected by the image sensor  460 . 
     As described above, the DLP display apparatus can provide a user interface such as the touch screen function and the light source recognition function. In particular, since only the image sensor  460  and the light source  470  are added to the DLP display apparatus, the light source recognition function can be implemented with a low cost. 
     Referring to  FIGS. 2 and 3 , a method for providing a user interface according to an exemplary embodiment is described in detail. 
       FIG. 2  is a flow chart illustrating a method for providing a user interface for a DLP display apparatus capable of recognizing a user&#39;s touch according to an exemplary embodiment of the present invention. 
     In operation S 210 , the light source  470  projects light for total reflection in the screen  450 . In this case, the light source  470  uses an infrared ray. This is because, although an infrared ray is diffused on the screen  450 , the infrared ray cannot be viewed by the user. In addition, because of using the infrared ray, touch by a pen or a touch pen as well as by the user&#39;s hand can be recognized. 
     In operation S 220 , if the user touches the screen  450 , light totally reflected in the screen  450  is diffused on the touched area of the screen  450 . 
     In operation S 230 , the DMD  430  reflects the diffused light towards the image sensor  460 . In this case, operation S 230  further includes an operation that the DMD  430  turns off the micro-mirrors in the DMD  430  for a certain period from among the periods corresponding to a single frame. This is because, if the micro-mirrors in the DMD  430  are turned on, the image sensor  460  cannot detect light. Accordingly, the micro-mirrors in the DMD  430  are turned off. 
     In operation S 240 , the image sensor  460  detects the light reflected by the DMD  430 . In particular, the image sensor  460  detects light reflected from at least one micro-mirror which is turned off in the DMD  430 . Accordingly, the image sensor  460  is disposed on an optical path of light reflected from the micro-mirror that is turned off in the DMD  430 . 
     In operation S 250 , the control unit  480  determines the touched area of the screen  450  using the information detected by the image sensor  460 . The information detected by the image sensor  460  may be image information in which only the diffused area is expressed brightly on the entire screen  450 . That is, the information detected by the image sensor  460  is image information indicating whether or not light is diffused for the entire screen  450 . Since the diffused area on the screen  450  indicates an area touched by the user, the control unit  480  can determine the touched area on the screen  450  using the information detected by the image sensor  460 . 
     Following this process, the DLP display apparatus can provide the touch screen function. 
       FIG. 3  is a flow chart illustrating a method for providing a user interface for the DLP display apparatus capable of recognizing light projected to the screen  450  according to another exemplary embodiment of the present invention. 
     In operation S 310 , the light source  470  externally projects light onto the surface of the screen  450 . In this case, the light source  470  may use a visible ray. For example, the light source  470  may be a laser pointer. More specifically, in a presentation, if a laser pointer projects a ray onto the screen  450  of the DLP display apparatus, the DLP display apparatus detects the projected area on the screen  450 . Hereinafter, a “light source recognition function” refers to a function for the DLP display apparatus recognizing an area on which the light source  470  is projected on the screen  450 . 
     In operation S 320 , the light projected from the outside of the screen  450  is diffused on the surface of the screen  450 . 
     In operation S 330 , the DMD  430  reflects the diffused light to the image sensor  460 . In this case, operation S 330  further includes an operation that the DMD  430  turns off the micro-mirrors in the DMD  430  for a certain period from among the periods corresponding to a single frame. This is because, if the micro-mirrors in the DMD  430  are turned on, the image sensor  460  cannot detect light. Accordingly, the micro-mirrors in the DMD  430  are turned off. 
     Subsequently, in operation S 340 , the image sensor  460  detects the light reflected from the DMD  430 . In particular, the image sensor  460  detects light reflected from at least one micro-mirror which is turned off in the DMD  430 . Accordingly, the image sensor  460  is disposed on an optical path of light reflected from the micro-mirror that is turned off in the DMD  430 . 
     In operation S 350 , the control unit  480  determines the area onto which the light source  470  projects the light on the screen  450 , using the information detected by the image sensor  460 . The information detected by the image sensor  460  may be image information in which only the diffused area is expressed brightly on the entire screen  450 . That is, the information detected by the image sensor  460  is image information indicating whether or not light is diffused for the entire screen  450 . Since the diffused area on the screen  450  indicates an area onto which the light source  470  projects the light on the screen  450 , the control unit  480  can determine the projected area on the screen  450  using the information detected by the image sensor  460 . 
     Following this process, the DLP display apparatus can provide the light source recognition function. 
     How the touch screen function and the light source recognition function are performed in the DLP display apparatus is described in detail with reference to  FIGS. 4 to 8 . 
       FIG. 4  illustrates a process of reflecting light of a display lamp from a DMD to a screen and displaying an image on the screen in a DLP display apparatus according to an exemplary embodiment of the present invention. 
     As illustrated in  FIG. 4 , the DMD  430  includes a first mirror  433 , a second mirror  436 , and a third mirror  439 .  FIG. 4  shows only a portion of the micro-mirrors in the DMD  430 , and it is apparent that the DMD  430  may further include additional mirrors. 
     The screen  450  includes a first area  453 , a second area  456 , and a third area  459 . The first area  453 , the second area  456 , and the third area  459 , which correspond to the first mirror  433 , the second mirror  436 , and the third mirror  439 , respectively. 
     The lens  490  focuses light between the screen  450  and the DMD  430 . 
     As illustrated in  FIG. 4 , the display lamp  410  irradiates a light beam, so that the light beam is filtered by the color wheel  420  (not shown in  FIG. 4 ) and projected to the DMD  430 . 
     Among the mirrors of the DMD  430 , light reflected from mirrors which are turned on is projected onto the screen  450 . More specifically, since the first mirror  433  is turned on, light reflected from the first mirror  433  is projected onto the first area  453  of the screen  450 . Since the second mirror  436  is turned off, light reflected from the second mirror  436  is projected onto the light absorbing unit  440 . Since the third mirror  439  is turned on, light reflected from the third mirror  439  is projected onto the third area  459  of the screen  450 . Therefore, on the screen  450 , only the first area  453  and the third area  459  are expressed brightly, and the second area  456  is expressed darkly. 
     By following the above principle, the DLP display apparatus can express an image on the screen  450 . 
       FIG. 5  illustrates a user touching the second area  456  on the screen  450  according to an exemplary embodiment of the present invention. 
     As illustrated in  FIG. 5 , the light source  470  projects light for total reflection in the screen  450 . In this case, the light source  470  uses an infrared ray. If the user touches the second area  456 , the total-reflected light is diffused on the second area  456 . 
     The diffused light passes through the lens  490 , is reflected by the second mirror  436 , and is projected to the image sensor  460 . Accordingly, the image sensor  460  detects the touch by the user on the second area  456  of the screen  450 . 
       FIG. 6  illustrates a user touching the first area  453  on the screen  450  according to the exemplary embodiment of the present invention. 
     As illustrated in  FIG. 6 , the light source  470  projects light for total reflection in the screen  450 . In this case, the light source  470  uses an infrared ray. If the user touches the first area  453 , the total-reflected light is diffused on the first area  453 . 
     The diffused light passes through the lens  490 , is reflected by the first mirror  433 , and is projected to the image sensor  460 . Accordingly, the image sensor  460  detects the touch by the user on the first area  453  of the screen  450 . 
     As described above, the touch screen function can be implemented by adding only the image sensor  460  and the light source  470  to the DLP display apparatus. 
       FIG. 7  illustrates light projected from the light source  470  to the second area  456  on the screen  450  according to another exemplary embodiment of the present invention. 
     As illustrated in  FIG. 7 , the light source  470  externally projects light onto the second area  456  of the screen  450 . In this case, the light source  470  may be a light source using a visible ray (for example, a laser pointer). As illustrated in  FIG. 7 , light projected by the light source  470  is diffused on the second area  456 . 
     The diffused light passes through the lens  490 , is reflected by the second mirror  436  of the DMD  450 , and is projected to the image sensor  460 . Accordingly, the image sensor  460  detects the projection of the light source  470  on the second area  456  of the screen  450 . 
       FIG. 8  illustrates light projected from the light source  470  to the first area  453  on the screen  450  according to another exemplary embodiment of the present invention. 
     As illustrated in  FIG. 8 , the light source  470  externally projects light onto the first area  453  of the screen  450 . In this case, the light source  470  may be a light source using a visible ray (for example, a laser pointer). As illustrated in  FIG. 8 , light projected by the light source  470  is diffused on the first area  453 . 
     The diffused light passes through the lens  490 , is reflected by the first mirror  433  of the DMD  450 , and is projected to the image sensor  460 . Accordingly, the image sensor  460  detects the projection of the light source  470  on the first area  453  of the screen  450 . 
     As described above, the light source recognition function can be implemented by adding only the image sensor  460  and the light source  470  to the DLP display apparatus. 
     If the DLP display apparatus has the touch screen function or the light source recognition function as described above, an optic axis of light displayed on the screen is the same as an optic axis of light used to recognize touch or a light source, so calibration or correction is not needed. Therefore, calibration and distortion between coordinates of the image and coordinates of the touch area can be minimized. 
     In the above exemplary embodiments, the DLP display apparatus may be any kind of display apparatus using the DLP technology, such as a DLP television for example. 
     As can be appreciated from the above description of the exemplary embodiments of the present invention, a method for providing a user interface, by which a DMD reflects light emitted from a light source to a screen and an image sensor detects the light reflected from the DMD, and a DLP display apparatus using the method are provided, so as to more easily provide a user interface for the DLP display apparatus. 
     The foregoing exemplary embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.