Patent Publication Number: US-2003222849-A1

Title: Laser-based user input device for electronic projection displays

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to interaction schema for computer displays and, in particular, to providing an interaction schema for a projection display through a hand-held, untethered narrow-beam visible light pointer that is operable by a user to direct narrow-beam visible light to the display screen.  
       BACKGROUND AND SUMMARY  
       [0002] There is a wide variety of interaction schema by which users can interact with computer displays, and particularly graphical user displays. For a single-operator computer, for example, the interaction schema may include any graphical user input device including a computer mouse, trackball, joystick, touch-pad, touch-screen, light pen, etc. These interaction schema relate well to the relatively close positioning between the user and the computer display.  
       [0003] However, not all electronic- or computer-based display systems are as well adapted to such conventional interaction schema. For example, some electronic- or computer-based display systems project a display image onto a display screen for viewing by typically multiple viewers. Commonly, at least one viewer is making a presentation to one or more observing viewers, but such display systems may be used in other applications as well. These display systems employ an electronic or multimedia projector that may use liquid crystal cells, digital micromirrors, etc. to form a display image that is projected onto a display screen. Such electronic projectors are available under a variety of trademarks including Sony®, Hitachi®, Sharp®, In Focus®, Epson®, etc.  
       [0004] In a common use of an electronic projector, the user, operator, or presenter controlling the projector is commonly separate from the projector and possibly even mobile relative to it. In this context, a conventional graphical user input device like a computer mouse is untenable. Accordingly, electronic projector manufacturers have developed untethered radio frequency or infrared remote controls to direct a range of dedicated control signals to a receiver associated with an electronic projector. These remote control devices allow a user to provide a range of commands to the electronic projector from various remote positions relative to the projector.  
       [0005] In some instances, the user, operator, or presenter controlling the projector will also use a handheld “laser pointer” to point-out for others particular information projected onto the display screen. The laser pointer generates a narrow beam of visible light that shines on the display as a spot that the user, operator, or presenter, and any other viewers, can see. In one instance, a conventional infrared electronic projector remote control includes an integral laser pointer for pointing to a projected display image. Such an infrared remote control with integral laser pointer is available from In Focus Corporation as a LaserPro™ remote control.  
       [0006] A disadvantage of conventional wireless and infrared remote controls for electronic projectors is that the controllers are typically limited to predefined electronic projector operations. In some instances, an infrared or wireless remote control can also provide computer “mouse” control that is transmitted as infrared or radio frequency signals to a receiver. Corresponding graphical input controls signals are generated from the received infrared or radio frequency signals, and graphical user control of a cursor is projected onto the display screen. A disadvantage is that such sophisticated remote controls are relatively expensive.  
       [0007] Accordingly, the present invention provides a remote electronic projection display control system and method that are associated with an electronic projector for projecting an image onto a display screen. The electronic projector may be positioned behind the display screen as a rear projection display, or in front of the display screen as a front projection display. With regard to the system, a narrow-beam visible light pointer, such as a laser pointer, is operable by a user to direct narrow-beam visible light to the display screen. A multi-pixel light sensor or camera is positioned to receive the narrow-beam visible light from the display screen.  
       [0008] A controller receives from the multi-pixel light sensor a signal corresponding to the narrow-beam visible light directed to the display screen. The controller correlates the narrow-beam visible light with a display screen location and generates a control signal based upon the display screen location. For example, the user may activate a graphical user interface control rendered on the display screen by pressing a light-controlling button that modulates the narrow-beam visible light. The multi-pixel light sensor would detect the modulation and the corresponding activation of the graphical control.  
       [0009] The present invention allows a simple, untethered handheld narrow-beam visible light pointer, such as a laser pointer, to provide complete graphical user interface control for a computer display such as an electronic projector. Such a controller forms a spot on the display so that the operator or user can see what graphical user interface control is being activated, thereby avoiding the problems of operating an infrared or wireless remote control device that relies on hard-to-read keypad markings for indicating the commands. Moreover, the narrow-beam visible light pointer, such as a laser pointer, can be markedly simpler and less expensive than infrared or radio frequency devices that provide graphical user interface control.  
       [0010] Additional objects and advantages of the present invention will be apparent from the detailed description of the preferred embodiment thereof, which proceeds with reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a diagrammatic illustration of a rear projection display system with a remote electronic projection display control system according to the present invention.  
     [0012]FIG. 2 is a diagrammatic illustration of a front projection display system with a remote electronic projection display control system according to the present invention.  
     [0013]FIG. 3 is a flow diagram of an electronic projection display control method for controlling an electronic projector that projects an image onto a display screen. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0014]FIG. 1 is a diagrammatic illustration of a rear projection display system  10  having an electronic projector  12  positioned behind a translucent display screen  14 . Electronic projector  12  is well-known in the art and may employ any of a variety of electronically-controlled display technologies including liquid crystal displays, digital micromirrors (e.g., DLP™ digital light processing light controllers available from Texas Instruments Incorporated), etc., together with appropriate projection optics.  
     [0015] Electronic projector  12  projects a display image on a rear surface of display screen  14  for viewing by one or more viewers  16  (one shown schematically) who are positioned in front of display screen  14 . Commonly, electronic projector  12  would be enclosed by a cabinet (not shown) that also supports display screen  14  about its periphery.  
     [0016] In accordance with the present invention, a hand-held, untethered directed-light pointer  20  is used by viewer  16  to direct a narrow beam  22  of visible light to the front surface of display screen  14 . (Directed-light pointer  20  is shown significantly enlarged for purposes of illustration.) For example, the narrow beam  22  of visible light may be directed to selected control areas (e.g., graphical control button  24 ) that are rendered on display screen  14  by electronic projector  12 . Control areas such as graphical control button  24  are analogous to graphical user interface controls common in computer applications. Directed light pointer  20  may include or be implemented as a laser pointer.  
     [0017] A portion of the narrow beam  22  of visible light is reflected from display screen  14  back toward viewer  16  and therefore forms a visible spot  26  where the beam  22  strikes display screen  14 . This allows viewer  16  to see where narrow beam  22  is directed and strikes display screen  14 . Another portion of the narrow beam  22  passes through translucent display screen  14  and forms a spot on the rear of display screen  14 . A multi-pixel light sensor or camera  30  is positioned behind display screen  14 , as is electronic projector  12 . Light sensor  30  receives light from the rear surface of display screen  14 , including the portion of the narrow beam  22  that passes through translucent display screen  14 .  
     [0018] Light sensor  30  preferentially detects the light from the directed light pointer  20  passing through translucent display screen  14 . The multiple pixels of light sensor  24  correspond to different positions or locations on display screen  14 . The location on display screen  14  of spot  26  is therefore detected by light sensor  30  and is provided to a system controller  32 . For example, light sensor  30  may operate as a frame capture camera that provides image information to system controller  32 . System controller  32  discerns spot  26  from the image information and correlates the location of spot  26  with the projected display image. Directed-light pointer  20 , light sensor  30 , and system controller  32  together operate as a remote electronic projection display control system.  
     [0019] Directed-light pointer  20  includes one or more viewer-operable keys or buttons (not shown) that the viewer may operate to activate, select, or “click” a control area such as graphical control button  24 . The one or more viewer-operable buttons (e.g., typically at least two) would correspond to, and provide the same functionality as, the buttons on a conventional user input device like a computer mouse. In one implementation, user-operation of each button could cause narrow beam  22  to be modulated at a frequency unique to the operated button. The modulation could be at a frequency higher than that perceptible by the viewer.  
     [0020] An advantage of directed-light pointer  20  is that it is remote from and not tethered to projection display system  10 . This gives the viewer optimal freedom of movement relative to projection display system  10 , even at relatively large distances of 10 meters or more.  
     [0021] Light sensor  30  may be adapted to preferentially detect the light from the directed light pointer  20  by placement of a narrow-band color filter between light sensor  30  and the rear surface of display screen  14 . The narrow-band color filter would be adapted to pass a narrow color band of light corresponding to the light transmitted from directed-light pointer  20 . Alternatively, the light from the directed light pointer  20  may be preferentially detected by application of an electronic color filter that preferentially passes to controller system  32 , or identifies within controller  32 , image information of the color corresponding to the light from the directed-light pointer  20 .  
     [0022] As another alternative implementation, two or more directed-light pointers  20  may be used simultaneously with projection display system  10 , such as by different viewers. Each of the plural directed-light pointers  20  could transmit a narrow beam  22  of a different color so that the corresponding visible spots  26  can be distinguished by viewers and by one or more light sensors  30 . In one implementation, a different light sensor  30  could be configured with a narrow-band color filter to receive the light from just one of the directed-light pointers  30 .  
     [0023] In one exemplary implementation, light sensor  30  may have an array of at least 320×240 pixels so that it is of small size and low cost. In use with a display screen  14  with dimensions of 12.5 inches-by-34 inches (about 32 cm-by-86 cm), for example, such a light sensor  30  can provide reasonably precise location information. With the 32 inch width, the 320 horizontal TV pixels would yield 0.1″ horizontal screen position sensing. Vertically, the precision would be about 0.05 inches.  
     [0024]FIG. 2 is a diagrammatic illustration of a front projection display system  50  having an electronic projector  52  positioned in front of a reflective display screen  54  with a viewer  56 . Electronic projector  52  is well-known in the art and may employ any of a variety of electronically-controlled display technologies including liquid crystal displays, digital micromirrors (e.g., DLP™ digital light processing light controllers available from Texas Instruments Incorporated), etc., together with appropriate projection optics. Electronic projector  52  projects a display image on a front surface of display screen  54  for viewing by one or more viewers  56  (one shown schematically) who are also positioned in front of display screen  54 .  
     [0025] Directed-light pointer  20  is used by viewer  56  to direct a narrow beam  22  of visible light to the front surface of display screen  54 . For example, the narrow beam  22  of visible light may be directed to selected control areas (e.g., graphical control button  58 ) that are rendered on display screen  54  by electronic projector  52 . Control areas such as graphical control button  58  are analogous to graphical user interface controls common in computer applications.  
     [0026] The narrow beam  22  of visible light is reflected from display screen  54  back toward viewer  56  and therefore forms a visible spot  60  where the beam  22  strikes display screen  54 . This allows viewer  56  to see where narrow beam  22  is directed and strikes display screen  54 . A multi-pixel light sensor or camera  62  is positioned to receive light reflected from display screen  54 . For example, light sensor  62  may be positioned or integrated with electronic projector  52 . Light sensor  62  receives light from the front surface of display screen  54 , including the portion of the narrow beam  22  that is reflected by display screen  54 .  
     [0027] Light sensor  62  preferentially detects the light from the directed light pointer  20  and reflected by display screen  54 . The multiple pixels of light sensor  62  correspond to different positions or locations on display screen  54 . The location on display screen  54  of spot  60  is therefore detected by light sensor  62  and is provided to a system controller  64 . For example, light sensor  62  may operate as a frame capture camera that provides image information to system controller  64 . System controller  64  discerns spot  60  from the image information and correlates the location of spot  60  with the projected display image. In other regards, the operation of system controller  64  is the same as that of system controller  32 .  
     [0028]FIG. 3 is a flow diagram of an electronic projection display control method  100  for controlling an electronic projector that projects an image onto a display screen.  
     [0029] Process block  102  indicates that a narrow visible light beam is manually directed to a display screen of an electronic projection display by a user or viewer. For example, the user or viewer may manually operate a hand-held, untethered, remote narrow-beam visible light source (e.g., a laser pointer).  
     [0030] Process block  104  indicates that a multi-pixel light sensor receives the narrow-beam visible light from the display screen.  
     [0031] Process block  106  indicates that the narrow-beam visible light from the display screen is correlated with a display screen location.  
     [0032] Process block  108  indicates that a control signal based upon the display screen location is obtained. For example, the control signal may be obtained in response to a variation or change in the light beam (e.g., a modulation) while it strikes a graphical control element or another display element. The variation or change can occur in response to user activation of a light beam control button on the hand-held, untethered, remote narrow-beam visible light source.  
     [0033] Having described and illustrated the principles of our invention with reference to an illustrated embodiment, it will be recognized that the illustrated embodiment can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of our invention may be applied, it should be recognized that the detailed embodiments are illustrative only and should not be taken as limiting the scope of our invention. Rather, I claim as my invention all such embodiments as may come within the scope and spirit of the following claims and equivalents thereto.