Abstract:
Each opto-mechanical pointing device includes a housing having a base that two or more rollers extend beyond to make contact with a surface. An optical module that includes a light source and a detector track the motion of the opto-mechanical pointing device directly or indirectly. Light reflecting off markings positioned opposite of each detector is used to determine the speed and distance traveled by an opto-electrical pointing device. Alternatively, the speed and distance traveled by an opto-electrical pointing device is determined by monitoring the tilt or rotation of the opto-mechanical pointing device with respect to the surface beneath the pointing device.

Description:
BACKGROUND 
     Pointing devices have been used with computers and other types of electronic systems for many years. A computer mouse is one example of a pointing device. With a mechanical mouse, a ball rolls over a surface as the mouse is moved. Interior to the mouse are wheels that contact the ball and convert its rotation into electrical signals representing orthogonal components of motion. 
     Another type of pointing device is an optical mouse. As an optical mouse moves over a surface, light emitted from a light source within the mouse reflects off the surface and is detected by a motion sensor positioned within the mouse. The motion sensor typically includes a camera that captures images of the surface. The motion sensor analyzes a sequence of images to determine the speed and distance the mouse has moved across the surface. 
     A basic optical mouse needs particular surface properties in order to accurately determine the motion of the mouse. When a surface is formed from a smooth material such as glass, or includes a reflective material such as a mirror, the absence of surface features in the surface means the motion sensor is unable to acquire the amount of data needed to determine the motion of the mouse. 
     Alternative optical techniques have been investigated to address this problem. Speckle and other interferometric techniques measure variations in the surface on the scale of the wavelength of light. These small variations create interference patterns that can, in theory, be used to determine motion. Unfortunately, the surface variations in clean, undamaged glass are not sufficient to create strong optical signals, making it difficult for the motion sensor to determine the motion of the optical mouse. 
     SUMMARY 
     In accordance with the invention, opto-mechanical pointing devices that track the movement of rollers positioned at the base of the pointing devices are provided. The opto-mechanical pointing devices each include a housing having a base that two or more rollers extend beyond to make contact with a surface. One or more detectors track the motion of the two or more rollers directly or indirectly. 
     When the motion of the rollers is tracked directly, at least two rollers moving in orthogonal directions with respect to each other include reflective markings or scattering white paint markings. An optical module detects light reflected off the markings of a respective moving roller. Thus, from the perspective of each detector, the light reflected off the respective markings pulses at a rate based on the motion of the corresponding roller. Using this information, a processing device is able to determine the speed and distance traveled for the opto-mechanical pointing device. 
     When the motion of the rollers is tracked indirectly, each optical module detects light reflected off a respective material that includes reflective markings or scattering white paint markings in one embodiment in accordance with the invention. The material is wrapped around pairs of rollers and the light reflected off the markings pulses at a rate based on the motion of the respective pairs of rollers. Using this information, a processing device is able to determine the speed and distance traveled by the opto-mechanical pointing device. 
     In another embodiment in accordance with the invention, each detector detects light that is used to monitor the tilt or rotation of the pointing device with respect to the surface beneath the pointing device. As the opto-mechanical pointing device moves over a surface, the angle between the plane of the base of the pointing device and the plane of the surface varies. This variation causes the light reflected off the surface to strike different areas or pixels in one or more detectors. Using the predictably varying light measurements, a processing device is able to determine the speed and distance traveled by the opto-mechanical pointing device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a side view of a pointing device in an embodiment in accordance with the invention; 
         FIG. 2  depicts a bottom view of a first pointing device in an embodiment in accordance with the invention; 
         FIGS. 3A-3B  illustrate cross-sectional view of a portion of the first pointing device shown in  FIG. 2  through line A-A; 
         FIG. 4  depicts a bottom view of a second pointing device in an embodiment in accordance with the invention; 
         FIG. 5  illustrates a bottom view of a third pointing device in an embodiment in accordance with the invention; 
         FIG. 6  illustrates optical module  422  and a top view of roller  414  shown in  FIGS. 4 and 5 ; 
         FIG. 7  illustrates a side view of edge  600  of roller  414  shown in  FIG. 6 ; 
         FIG. 8  illustrates a top view of a longitudinal side of roller  414  shown in  FIG. 6 ; 
         FIG. 9  depicts a side view of a roller-optical component configuration for use in a fifth pointing device in an embodiment in accordance with the invention; and 
         FIG. 10  illustrates a top view of material  800  shown in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is presented to enable embodiments of the invention to be made and used, and is provided in the context of a patent application and its requirements. Various modifications to the disclosed embodiments will be readily apparent, and the generic principles herein may be applied to other embodiments. Thus, the invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the appended claims. Like reference numerals designate corresponding parts throughout the figures. 
     Referring now to  FIG. 1 , there is shown a side view of a pointing device in an embodiment in accordance with the invention. Pointing device  100  is shown in a conventional “mouse” shape in the embodiment shown in  FIG. 1 . Pointing device  100  includes housing  102  and base  104 . Rollers  106 ,  108  roll over surface  110  when a user holds housing  102  with his or her hand and moves pointing device  100  over surface  110 . Surface  110  can be a flat surface or a non-flat surface. 
     Pointing device  100  further includes a clicking region  112  that a user presses with his or her finger to interact with an image or a graphical user interface displayed on a monitor (not shown). Clicking region  112  allows a user to select icons, enter data, move scroll bars or sliders, and interact with or select other features displayed on the monitor. Scroll button  114  allows a user to scroll or move around a document or program displayed on the monitor. 
       FIG. 2  depicts a bottom view of a first pointing device in an embodiment in accordance with the invention. Openings  200 ,  202 ,  204 ,  206  are formed through base  208 . Rollers  210 ,  212 ,  214 ,  216  partially extend out of openings  200 ,  202 ,  204 ,  206 , respectively, to make contact with a surface (e.g.,  110  in  FIG. 1 ). Opening  218  is also formed through base  208  and is configured such that a light source (not shown) located within the housing (not shown) can emit light towards the surface and a detector (not shown) located with the housing can detect the light reflected off the surface. 
     Rollers  212 ,  216  roll in the direction indicated by arrow  220  and have an axis of rotation  222  that is perpendicular to the direction of movement. Rollers  210 ,  214  roll in the direction indicated by arrow  224  and have an axis of rotation  226  that is perpendicular to the direction of movement. The direction of movement for rollers  212 ,  216  is orthogonal to the direction of movement for rollers  210 ,  214  in an embodiment in accordance with the invention. Although the embodiment shown in  FIG. 2  depicts four rollers, in other embodiments in accordance with the invention two or more rollers may be used, with at least one roller oriented for axis of rotation  222  and one roller oriented for axis of rotation  226 . 
     Referring now to  FIGS. 3A-3B , there is shown a cross-sectional view of a portion of the first pointing device shown in  FIG. 2  through line A-A. Only those components necessary to understand the invention are shown in  FIGS. 3A-3B . Roller  212  has been omitted from  FIGS. 3A-3B  and rollers  210 ,  214  are shown completely outside of housing  102  for the sake of simplicity. 
     Pointing device  300  includes light source  302  and detector  304  that combined form an optical module in an embodiment in accordance with the invention. One or more optional lenses or apertures (not shown) may be positioned in the optical path between light source  302  and detector  304 . Light source  302  is typically implemented as a light-emitting diode and detector  304  as an imaging detector. In the embodiment shown in  FIG. 3 , a single light source and a single two dimensional imaging detector are used. Other embodiments in accordance with the invention, however, are not limited to this configuration. For example, a light source and a detector are used with each axis of rotation in another embodiment in accordance with the invention. Light source  302  emits light  306  towards surface  110  located beneath pointing device  300 . Light source  302  emits light toward the surface at an oblique angle with respect to the surface in an embodiment in accordance with the invention. Light  308  reflects off surface  110  and is detected by detector  304 . Processing device  310  receives signals representing the light measurements from detector  304  and determines the speed and distance at which pointing device  300  is moved over surface  110 . 
     Rollers  210 ,  214  are asymmetric in shape and are oriented such that roller  210  and roller  214  are positioned differently as pointing device  300  moves over surface  110 . In one embodiment in accordance with the invention, roller  210  is locked together with roller  214  so that roller  210  is rolling over one of its ends as roller  214  is rolling over one of its sides, and vice versa. Rollers  210 ,  214  may be locked together, for example, using a belt or gears. The shape and size of rollers  210 ,  214  are designed to minimize this “rolling motion” so a user is not aware or significantly aware of the changes in distance between base  208  and surface  110 . 
     The shape and size of rollers  210 ,  214  are also designed to vary the distance (d n ) between an edge of base  208  and surface  110  in a determinable manner.  FIG. 3A  illustrates the distance between the right edge of base  208  and surface  110  varying as pointing device  300  moves over surface  110 . At this point, angle θ between the plane of base  208  and the plane of surface  110  is at a maximum, positive value. The plane of base  208  and the plane of surface  110  are represented in  FIG. 3A  by the dashed lines. 
     As pointing device  300  continues to move over surface  110 , rollers  210 ,  214  eventually reach the point where the distance (d) between the right edge of the plane of base  208  and the plane of surface  110  is at its maximum value. The angle θ between the plane of base  208  and the plane of surface  110  is negative. 
     Because angle θ varies as pointing device  300  moves over surface  110 , light  308  strikes different areas or pixels in detector  304 . Using the predictably varying light measurements, controller  310  determines the speed and distance at which pointing device  300  moves over surface  110 . 
     Although  FIGS. 3A-3B  illustrate only two of the four rollers shown in  FIG. 2 , rollers  212 ,  216  are also asymmetric in shape in an embodiment in accordance with the invention. In another embodiment in accordance with the invention, only one roller for each axis of rotation is asymmetric in shape. Moreover, the speed and distance at which pointing device  300  is moving over surface  110  can be determined differently in other embodiments in accordance with the invention. By way of example only, a plate is formed over a portion of detector  304  that causes light  308  to be detected only when the value of angle θ is greater than or equal to a given value. The plate blocks light  308  from detector  304  when angle θ is less than the given value. Thus, light  308  appears as a pulsing light when viewed from the perspective of detector  304 . The rate of pulsing is then used to determine the speed of pointing device  300  and distance it traveled. 
     In another embodiment in accordance with the invention, the size and positioning of detector  304  is designed to receive reflected light  308  only when the value of angle θ is less than or equal to a given value. Detector  304  does not detect light or much light when angle θ is greater than the given value. Light  308  appears as a pulsing light when viewed from the perspective of detector  304 . The rate of pulsing is then used to determine the speed of pointing device  300  and distance it traveled. 
       FIG. 4  depicts a bottom view of a second pointing device in an embodiment in accordance with the invention. Openings  400 ,  402 ,  404 ,  406  are formed through base  408 . Rollers  410 ,  412 ,  414 ,  416  partially extend out of openings  400 ,  402 ,  404 , 406 , respectively, to make contact with a surface (e.g.,  110  in  FIG. 1 ). Opening  218  is also formed through base  408  and is configured such that a light source (not shown) can emit light towards a surface and a detector (not shown) can detect the light reflected off the surface. 
     Rollers  410 ,  412 ,  414 ,  416  are cylindrical-shaped rollers in an embodiment in accordance with the invention. Rollers  412 ,  416  roll in the direction indicated by arrow  220  and have an axis of rotation  222  that is perpendicular to the direction of movement. Rollers  410 ,  414  roll in the direction indicated by arrow  224  and have an axis of rotation  226  that is perpendicular to the direction of movement. The direction of movement for rollers  412 ,  416  is orthogonal to the direction of movement for rollers  410 ,  414  in an embodiment in accordance with the invention. Although the embodiment shown in  FIG. 4  depicts four rollers, in other embodiments in accordance with the invention two or more rollers may be used, with at least one roller oriented for axis of rotation  222  and one roller oriented for axis of rotation  226 . 
     Optical modules  418 ,  420 ,  422 ,  424  are positioned adjacent to rollers  410 ,  412 ,  414 ,  416 , respectively. Optical modules  418 ,  420 ,  422 ,  424  are shown with dashed lines in  FIG. 4  because optical modules  418 ,  420 ,  422 ,  424  are constructed within the housing (not shown) of a pointing device. Each optical module includes a light source and a rotary encoder or detector in an embodiment in accordance with the invention. Other embodiments in accordance with the invention include one or more lenses in each optical module. An optical module is described in more detail in conjunction with  FIG. 6 . 
     Referring now to  FIG. 5 , there is shown a bottom view of a third pointing device in an embodiment in accordance with the invention. Openings  404 ,  406  are formed through base  500 . Rollers  414 ,  416  partially extend out of openings  404 ,  406  respectively, to make contact with a surface (not shown). Opening  218  is also formed through base  500  and is configured such that a light source (not shown) can emit light towards a surface and a detector (not shown) can detect the light reflected off the surface. 
     Roller  416  rolls in the direction indicated by arrow  220  with an axis of rotation  222  that is perpendicular to the direction of movement. Roller  414  rolls in the direction indicated by arrow  224  with an axis of rotation  226  that is perpendicular to the direction of movement the direction of movement for roller  416  is orthogonal to the direction of movement for roller  414 . Stationary pin  502  is formed as part of base  500  or is affixed to base  500  and is used to stabilize the pointing device as the pointing device rests on or moves over a surface. Although only one stationary pin is shown in  FIG. 5 , embodiments in accordance with the invention can include any given number of stationary pins configured to allow the two or more rollers to make contact with a surface. 
     Optical modules  422 ,  424  are positioned adjacent to rollers  414 ,  416 , respectively. Optical modules  422 ,  424  are shown with dashed lines in  FIG. 5  because optical modules  422 ,  424  are constructed within the housing (not shown) of a pointing device. Each optical module includes a light source and a detector in an embodiment in accordance with the invention. Other embodiments in accordance with the invention include one or more lenses in each optical module. An optical module is described in more detail in conjunction with  FIG. 6 . 
       FIG. 6  illustrates a top view of roller  414  and optical module  422  shown in  FIGS. 4 and 5 . As discussed earlier, roller  414  is a cylindrical-shaped roller in an embodiment in accordance with the invention. Optical module  422  is positioned opposite of edge  600  of roller  414 . Optical module  422  includes light source  302 , detector  304 , and lens  602  in an embodiment in accordance with the invention. In another embodiment in accordance with the invention, lens  602  is not included in optical module  422 . An aperture is substituted for lens  602  in yet another embodiment in accordance with the invention. 
     Light source  302  emits light towards edge  600 and edge  600  reflects the light. Detector  304  then detects the reflected light. Light source  302  and detector  304  are constructed as one component in an embodiment in accordance with the invention. In another embodiment in accordance with the invention, light source  302  is a separate component and is positioned near detector  304 . 
     Referring now to  FIG. 7 , there is shown edge  600  of roller  414  shown in  FIG. 6 . Edge  600  includes reflective rotary encoder markings  700  that are positioned opposite optical module  422 . The triangle-shaped markings represent a generally retro-reflective marking or a white scattering paint marking for easiest signal processing in an embodiment in accordance with the invention. As roller  414  rolls over a surface, light emitted by light source  302  reflects off reflective rotary encoder markings  700  on the portion of roller  414  located within the housing (not shown). Thus, from the perspective of detector  304 , the light reflected off edge  600  pulses at a rate based on the motion of roller  414 . Using this information, the speed of roller  414  and the distance it traveled are determined by a processing device (e.g.,  310  in  FIG. 3 ). 
       FIG. 8  illustrates a longitudinal side of roller  414  shown in  FIG. 6 . Longitudinal side  800  includes reflective rotary encoder markings  700  that are positioned opposite an optical module (not shown). As roller  414  rolls over a surface, light emitted by a light source reflects off reflective rotary encoder markings  700 . Thus, from the perspective of the detector, the light reflected off edge  600  pulses at a rate based on the motion of roller  414 . Using this information, the speed of roller  414  and the distance it traveled are determined by a processing device (e.g.,  310  in  FIG. 3 ). 
     Referring now to  FIG. 9 , there is shown a side view of a roller-optical component configuration for use in a fifth pointing device in an embodiment in accordance with the invention. A closed-loop of material  900  is wrapped around a pair of rollers  902 ,  904 .  FIG. 10  illustrates a top view of material  900  shown in  FIG. 9 . Reflective rotary encoder markings  1000  are formed on an outer surface of material  900 . 
     An optical module  906  ( FIG. 9 ) is positioned such that light emitted by light source  302  strikes the outer surface of material  900 . As rollers  902 ,  904  roll over a surface, light emitted by light source  302  reflects off reflective rotary encoder markings  1000  and is detected by detector  304 . From the perspective of detector  304 , the light reflected off material  900  pulses at a rate based on the motion of rollers  902 ,  904 . Using this information, the speed of rollers  902 ,  904  and the distance they traveled are determined by a processing device (e.g.,  310  in  FIG. 3 ).