Abstract:
A pointing device for use with a keyboard functions like a computer mouse. It incorporates a plurality of configurable function keys. The pointing device is composed of a rolling surface capable of rotation and translation that may activate a switch when it is depressed. An optical sensor monitors the rotation and translation of the rolling surface and translates that motion into communications interpretable by a mouse software driver. An edge sensor allows repositioning of the rolling surface without cursor movement when limits of travel are reached. The pointing device communicates with the computer through a serial communication facility such as a PS/2 or USB connection. The enclosure containing the rolling surface incorporates an aperture allowing a portion of the rolling surface to be available for manipulation, an elevated support surface for the keyboard and provision for palm rests.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/252,451, filed Nov. 21, 2000, the entire disclosure of which is incorporated herein by reference. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    N/A  
         BACKGROUND OF THE INVENTION  
         [0003]    The computer mouse has been the primary vehicle for users to control the movement of a cursor on a screen. One reason for this is that the action of the mouse uses very natural processes in the brain. The “point and click” sequence of moving the cursor to the desired position and depressing a button to select an action uniquely utilizes the existing brain pathways established over many years. Although the mouse has the physiological advantage among positioning devices because of its accurate feel and ease of use, it has disadvantages—principally in the amount of desk space required and in the fact that the hands must be removed from the keyboard to use the mouse. In addition, injuries have been recorded based on reaching an awkward distance to access the mouse or positioning the mouse at an incorrect height for ergonomic operation. It would be advantageous to eliminate the disadvantages associated with using a computer mouse.  
           [0004]    Alternate positioning devices that have been developed to replace the mouse include the trackball, the touchpad, the joystick, the touch sensitive screen and devices tailored for particular applications. The touch sensitive screen and joystick do not address the issue of keeping the hands engaged with the keyboard. The trackball, touchpad and other special devices have typically been integrated into a special keyboard in order to keeping the hands in typing position. Nonetheless, users have not adopted these devices as readily as they have the mouse.  
           [0005]    Rollerbar devices have been developed that relied on separate sensors to sense rotational and translational movement of a bar. These have not met with great success. One device retained the mouse and its interface to the computer but adapted it to a rollerbar configuration. This device captured the mouse in a pad that placed a rollerbar under the mouse&#39;s ball. As the rollerbar moved, it moved the mouse ball so that the mouse sent the appropriate signals to the computer. The rollerbar could be positioned directly abutting the keyboard space bar. In addition to the rollerbar under the mouse ball, the device incorporated a pair of movable pads that were connected to the mouse buttons. By depressing the pads, the mouse buttons were depressed. While this device worked, it did not accommodate all computer mouses and did not have the intuitive feel of the mouse.  
           [0006]    A positioning device that is controllable while the hands remain on the keyboard in order to increase productivity is needed. In addition, the positioning device should minimize strain on wrist and shoulder while providing fast and precise positioning functions as an add-on to existing keyboards.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    An ergonomic positioning device provides an interactive positioning device, useable with a standard keyboard, that minimizes strain on wrist and shoulders while providing fast, intuitive and precise positioning functions. The ergonomic positioning device incorporates a movable surface, such as a rollerbar, and function buttons positioned so they are reachable while a user is typing on the keyboard. The full range of functions normally available on a mouse is provided by the ergonomic positioning device.  
           [0008]    The cursor positioning function is accomplished in one embodiment by a rollerbar that rotates for vertical screen positioning and translates for horizontal screen positioning. Once the cursor has been positioned, action is initiated by depressing “clicking” the rollerbar or one of the function buttons. Function button action and click tension of the rollerbar are configurable for user preference.  
           [0009]    The ergonomic positioning device is a highly accurate positioning device that requires minimum maintenance. A single optical sensor monitors the rollerbar or other movable surface, detecting changes in position that are transmitted to the computer. The optical sensor focuses on the curved surface of the rollerbar and is mounted at an internal position that assures the rollerbar and sensor are always positioned correctly. Further, the sensor location is selected so that when the rollerbar is clicked, the extent of rollerbar vertical displacement is limited.  
           [0010]    The ergonomic positioning device incorporates a tray that allows operation of the ergonomic positioning device and keyboard in non-traditional attitudes, such as positioned on the lap, as well as standard orientations. This tray further assures that the keyboard is elevated sufficiently above the rollerbar for ergonomic comfort and the tray provides palm rests for the user.  
           [0011]    For applications where other positioning devices are better suited, the ergonomic positioning device provides a pass through facility for PS/2 positioning devices. Other aspects, features, and advantages of the present invention are disclosed in the detailed description that follows.  
       
    
    
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0012]    The invention will be understood from the following detailed description in conjunction with the drawings, of which:  
         [0013]    [0013]FIG. 1 is a perspective view of an ergonomic positioning device assembly with keyboard according to the invention;  
         [0014]    [0014]FIG. 2 is a perspective view of the ergonomic positioning device assembly of FIG. 1 with a cover removed.  
         [0015]    [0015]FIG. 3 is a detail view of a rollerbar support assembly according to the invention;  
         [0016]    [0016]FIG. 4 is a bottom view of the ergonomic positioning device of FIG. 1;  
         [0017]    [0017]FIG. 5 is an end view of the rollerbar of FIG. 3;  
         [0018]    [0018]FIG. 6 is a detail view of an optical sensor mounting according to the invention;  
         [0019]    [0019]FIG. 7 is a close-up perspective view of the rollerbar and spacebar of the ergonomic positioning device of FIG. 1;  
         [0020]    [0020]FIG. 8 is a side view of a keyboard tray according to the invention;  
         [0021]    [0021]FIG. 9 is a perspective view of a PS/2 port for an alternate positioning device in the ergonomic positioning device assembly of FIG. 1;  
         [0022]    [0022]FIG. 10 is a block diagram of logic associated with an auxiliary positioning device according to the invention;  
         [0023]    [0023]FIG. 11 is a view of the internals of the ergonomic positioning device assembly according to the invention;  
         [0024]    [0024]FIG. 12 is a view of the underside of an ergonomic positioning device according to the invention;  
         [0025]    [0025]FIG. 13 is a perspective view of an alternate rollerbar and sensor assembly according to the invention;  
         [0026]    [0026]FIG. 14 is an illustration of an alternate embodiment of a rollerbar mounting mechanism;  
         [0027]    [0027]FIG. 15A, 15B and  15 C are alternate embodiments of rollerbars according to the invention; and  
         [0028]    [0028]FIG. 16 is an end view of a rollerbar illustrating possible placements of a sensor according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    The ergonomic positioning device is an accessory for a computer keyboard designed to be a cursor motion-control device that allows the user&#39;s hands to remain in typing position while using the ergonomic positioning device. The ergonomic positioning device further incorporates a keyboard tray with palm rests for ergonomic positioning during use on a desk or in non-desk use, such as resting the keyboard and ergonomic positioning device on the knees. The ergonomic positioning device provides a movable (rotatable and translatable) surface within reach of the user&#39;s thumbs when in normal typing position and manipulatable by the fingers without disruptive displacement of the hand. With an optionally enabled switch mounted so that it can be closed by depressing the movable surface, the ergonomic positioning device very closely emulates the action of a mouse producing a single button press action without perceptible x and y motion of the cursor. The ergonomic positioning device attaches to an existing keyboard, takes advantage of existing mouse drivers and allows connection of the ergonomic positioning device and another positioning device concurrently. Additional function buttons complete the mouse emulation. The movable surface is conveniently implemented as a rollerbar in one implementation to be fully described, but a rollerball and a surface supported by rolling mechanisms are alternate implementations.  
         [0030]    [0030]FIG. 1 illustrates an embodiment of the ergonomic positioning device  50 , implemented with a rollerbar  547  as utilized with a typical keyboard  52 . The keyboard  52  rests on the keyboard tray  60  with an enclosure  56 , having a longer right side and a shorter left side, oriented to place the rollerbar  54  centered beneath the spacebar  62 . Depressing the rollerbar  54  closes a switch (not shown) performing the same function as depressing a left button on a mouse. Function keys and scroll wheel  58  are centered on the ergonomic positioning device  50  further away from the spacebar  62  than the rollerbar  54 . Palm rests  64  may be incorporated in the ergonomic positioning device  50 .  
         [0031]    The keyboard tray  60  is designed to slide under the keyboard  52  holding the enclosure  56  against the keyboard and providing a balancing point for non-desk uses. The keyboard tray  60  makes it convenient to utilize the keyboard  52  and ergonomic positioning device  50  together in a casual position, such as with the combination balanced on the user&#39;s knees.  
         [0032]    When the keyboard  52  is positioned on the ergonomic positioning device  50 , the user&#39;s thumbs and fingers easily reach the rollerbar  54 , function keys and scroll wheel  58  with the hands in a touch-typing orientation. Rotation of the rollerbar  54  causes vertical cursor motion on a screen (not shown), while lateral motion of the rollerbar  54  causes a horizontal cursor motion on the screen. Rotation and translation simultaneously is also supported. The configurable function keys and scroll wheel  58  (described below) complete the replication of mouse functions.  
         [0033]    [0033]FIG. 2 is an internal view of the ergonomic positioning device embodiment of FIG. 1. The rollerbar assembly  54  is composed of a durable metal rod  70 , such as stainless steel or aluminum, thin enough that the rod has some springiness, that spans most of the width of the ergonomic positioning device  50 . A sleeve  72  of light metal, ceramic or plastic with an inner diameter slightly greater than the outer diameter of the rod  70  surrounds a significant portion of the rod  70 . In one embodiment, the sleeve  72  surrounds approximately 75% of the rod  70 . In this implementation, the outer surface of the sleeve  72  is coated with a matte rubberized surface that provides a good tactile feel for the user. In one embodiment, the outer diameter of the sleeve is greater than 8 mm and preferably approximately 12 mm. The rollerbar may be configured differently as is discussed below. The sleeve  72  is closed with bearings  74 , serving as a cap, of nylon, Teflon™, plastic or similar material having a centered hole with a diameter just slightly larger than the diameter of the rod  70 . These bearings  74  cushion the ends of sleeve  72  and provide a bearing surface that allows the sleeve  72  to move easily around and along the rod  70 . An end cap  76  is fastened to an end of rod  70  distal from a mounting arrangement  71 .  
         [0034]    [0034]FIG. 3 illustrates an end support of the rod  70  where it is cantilevered from a mount  82 . The rod  70  is supported in mount  82  at an upward angle from horizontal, the angle sufficient to cause the rod  70  to form a bow between the mounting arrangement  71  and the distal end  100  of the rod  70 . Typically, this angle is between approximately ½ and 3°. In an alternate embodiment (not shown), the rod  70  is mounted horizontally in a block and the block is tilted upward relative to the base  112  of the ergonomic positioning device  50  by an adjustable screw to from the bow.  
         [0035]    The end cap  76  of the rollerbar  54  terminates approximately horizontally level with the mount  82 . The end cap  76  is floating on an end switch (not shown) in the rest position. The rollerbar  54  forms a slightly bowed shape. The bowed rollerbar  54  has a measure of springiness that is utilized in depressing the end switch as described below. The exact shape of the rollerbar arch is adjustable by a tension adjuster  84  shown in FIG. 3. The tension adjuster  84  is spaced slightly away from the mount  82 . The rod  70  rests on the tension adjuster  84 . If the height of the tension adjuster  84  is increased from the minimum, the angle of the rollerbar  54  from horizontal is increased from the angle established by the mounting arrangement  71 . This greater angle increases the force needed to close the switch as discussed below, thereby minimizing inadvertent switch closures.  
         [0036]    [0036]FIG. 4 illustrates the way the tension adjuster  84  is set. Dial  88  is accessible from the bottom  86  of the ergonomic positioning device  50 . As shown in the detail of FIG. 4, there are multiple tension settings ranging from the slightest  92  to the largest  90 . As the user moves pointer  94  to turn the dial  88 , the height of tension adjuster  84  under rollerbar  54  increases, producing the tension best suited to the user&#39;s touch.  
         [0037]    [0037]FIG. 5 illustrates the switch mechanism for a clickable rollerbar  54 . The distal end  100  of the rollerbar  54  passes through alignment gateway  80  before being capped with end cap  76  that rests on a microswitch  98  mounted vertically on its housing  96 . When the highest tension from tension adjuster  84  is applied, the end cap  76  of rollerbar  54  floats, barely touching the switch  98 . Even when the user applies some pressure to the sleeve  72  to roll and slide the rollerbar  54 , the switch  98  is not activated. However, when the user deliberately presses on the rollerbar  54 , the bow of the rollerbar  54  is flattened and the switch  98  is activated. In some embodiments, as is known in the industry, the switch  98  emits an audible click coincident with its activation. The click provides instantaneous feedback to the user. The ability to move the cursor with the rollerbar  54  and select a function by “clicking” the rollerbar  54  most closely matches the physiological process achieved with a mouse.  
         [0038]    As can be seen in FIG. 2, an access enclosure  102  defines the area for user interaction with the rollerbar  54 . The access enclosure  102  is positioned to align with the keyboard spacebar  62  and is midway between a sensor  106  that monitors rollerbar movement and the left end  101  of the ergonomic positioning device  50  assembly. The access enclosure  102  is always spanned by a part of the sleeve  72  of the rollerbar  54  and the sleeve  72  does not normally touch the edges of the access enclosure  102 . As the bar is translated, the distal end  74 ′ of sleeve  72  lies in the area between alignment gateway  80  and the distal end  108  of the access enclosure  102 . The proximate end  74  of sleeve  72  lies in the area between alignment gateway  78  and a spot  104  near the proximate edge of the sensor  106 . The sensor  106  is placed at the location shown to assure that a portion of the sleeve  72  always remains over the sensor  106  while allowing maximum horizontal traverse of the rollerbar  54 . This location is displaced from the proximate end  110  of the access enclosure  106  by approximately the distance that distal end  74 ′ travels.  
         [0039]    Optical mouse sensors were developed to be used in optical mouses where the sensor is focused on a flat surface lying a fixed distance beneath the mouse. These sensors monitor the texture of the surface passing beneath the sensor, comparing successive images to determine the movement of the mouse. After research, it was found that the Solid-State Optical Mouse Sensor HDNS-2000 from Agilent Inc. could be focused on a rounded surface such as a cylindrical tube. The sensor focus is aligned with the axis of the tube to provide a sufficiently flat monitored surface. For suitably textured surfaces, the movement of cylinders having a diameter as small as 8 mm can be reliably tracked.  
         [0040]    As illustrated in FIG. 6, in the ergonomic positioning device, an optical mouse sensor  106 , such as the Solid-State Optical Mouse Sensor HDNS-2000 from Agilent Inc. is mounted beneath the rollerbar  54  through a printed circuit board  115  and touching, or through, a base plate  112 . The optical sensor  106  is aligned with the axis of the rollerbar and focuses upward at the cylindrical sleeve  72 . The single sensor  106  is very high resolution and detects the rotational and translational movement of the rollerbar  54 . For the clickable rollerbar  54  of FIG. 6, the sensor  106  is placed so that the vertical motion of the bar  54  when “clicked” has minimal effect on the focus of the sensor  106 . Keeping the distance between the mount  82  and the sensor  106  to a minimum optimizes the insensitivity to vertical motion. While the insensitivity to vertical motion could be further reduced, a measure of the horizontal range of the sleeve  72  would have to be sacrificed, as discussed above. Therefore, the proximate end  74  of the sleeve  72  travels between the position shown in FIG. 2 and position  104 , while the distal end  74 ′ of sleeve  72  travels between the access gateway  80  and the end  108  of the access enclosure  102 .  
         [0041]    One implementation of the motion sensor  58  functions by comparing images of the sleeve  72  at known time intervals to determine the movement. The sensor  106  detects patterns in sleeve  72  that may be coated with a rubber-like compound for tactile feedback to the user. The sleeve  72  and sensor  106  are spaced so that, when the rollerbar  54  is in the normal position, the lowest point of the sleeve  72  is centered in the focal range of the sensor  106 . As the rollerbar  54  is depressed, it remains essentially in focus. FIG. 6 illustrates a sensor mounting arrangement that has the sensor mechanism  114  mounted facing upward in a base plate/clip  116  that is fitted in a circuit board  118 . Alternate arrangements of rollerbar  54  and sensor  106  are discussed below.  
         [0042]    [0042]FIG. 7 illustrates the relationship of a typical keyboard  52  and the ergonomic positioning device  50 . It is desirable that the keyboard space bar  62  be higher than any functioning surface on the ergonomic positioning device  50 , and in particular that the movable surface (rollerbar  54 ) be lower than the space bar  62 . In the typical keyboard  52 , the space bar  62  is 28 mm above the surface on which the keyboard  52  rests. In the embodiment of FIG. 2, the minimum height of the sensor  106  facing upward toward the rollerbar  54  is 21 mm high and the rollerbar  54  with sleeve  72  is from 8 to 12 mm in diameter, placing the top surface of the rollerbar  54  above the spacebar  62 . FIG. 8 illustrates how the ergonomic positioning device  50  corrects this by raising the back  150  of the enclosure  56  and the top  152  of the keyboard tray  60  sufficiently to lift the spacebar  62  above the rollerbar  54 . Alternate layouts, as discussed below also minimize the height discrepancy.  
         [0043]    The ergonomic positioning device  50  can utilize either a USB or PS/2 serial connection to a computer system. While the USB connection provides a daisy chain capability, the PS/2 serial protocol does not. The ergonomic positioning device  50  facilitates the concurrent connection of a PS/2 compatible device (not shown) to the computer with the connection of the ergonomic positioning device  50 . As shown in FIG. 9, the ergonomic positioning device  50  incorporates a PS/2 port  164  on the backside-of the enclosure  56  for connecting an additional PS/2 device. Internal logic, as illustrated in FIG. 10, passes the bus functions received at block  160  onto the PS/2 port  164  after passing through a conversion block  162  if necessary. Signals returning from the PS/2 port  164  are ORed in block  168  with switch closures and sensor inputs from the ergonomic positioning device  50 . In this way, any combination of switch closures and cursor controls of either the ergonomic positioning device  50  or the PS/2 device may be used to interact with the computer.  
         [0044]    When the ergonomic positioning device  50  is implemented with a rollerbar  54 , there is an issue of the rollerbar  54  running out of area for horizontal travel. Coping with this issue is addressed in one of two ways, with and without edge detection. FIG. 11 illustrates the mechanisms used when edge detection is enabled. When the rollerbar reaches one of the travel limits, a limit lever  170 ,  170 ′ is pushed into the alignment gateways  78 ,  80  causing the limit lever  170 ,  170 ′ to depress a limit switch  172 ,  172 ′. When either limit switch  172 ,  172 ′ is depressed and edge detection is enabled, a cursor tracking function based on the sensor  106  output is suspended for a specified time. The specified time is long enough for a user to reposition the rollerbar  54  away from the travel limit. When the specified time expires, physically tracking the rollerbar  54  is restarted, while the cursor tracking function is reactivated at the prior screen location. If the user has repositioned the rollerbar  54 , further horizontal travel in the direction of the previous limit is now available.  
         [0045]    When edge detection is disabled, the cursor tracking function stops the screen horizontal cursor travel when the rollerbar  54  hits a limit lever (for instance lever  170 ). The user can free the up horizontal travel distance by driving rollerbar  54  into the opposite limit lever (for instance  170 ′) which causes the cursor tracking function to position the cursor at the screen edge corresponding to the opposite limit lever. The user now has the full horizontal travel distance of the rollerbar  54  available in the previously blocked direction.  
         [0046]    The configurable functions of the ergonomic positioning device  50  are controlled by DIP switches accessible from the bottom of the ergonomic positioning device  50  as shown in FIG. 12. In one embodiment, panel  174  is removable, revealing  8  switches. The switches control functions as detailed in Table 1.  
                           TABLE 1                                   Switch(es)   Function                           Switch 1   Turn Bar click ON and OFF           Switch 2   Turn End Detection ON and OFF           Switches 3 &amp; 4   See Table 2 - Control Left Button           Switches 5 &amp; 6   See Table 2 - Control Middle Button           Switches 7 &amp; 8   See Table 2 - Control Right Button                      
 
         [0047]    [0047]                               TABLE 2                                   Action   Even Switch ON   Even Switch OFF                           Odd Switch ON   Left Single Click   Left Double Click           Odd Switch Off   Drag Lock   Right click                        
         [0048]    [0048]FIG. 7 shows the three configurable function buttons, left— 176 , middle— 178  and right— 180 , that are positioned below rollerbar  54 . Table 2 detailed how each button can be configured to function as a specific mouse button as is known in the industry. Further fixed function buttons, such as the scroll wheel  144  and others may be incorporated in the ergonomic positioning device. Further, the buttons shown may be repositioned within thumb activation range as desired. If more than one function button is configured as the same mouse button, the ergonomic positioning device  50  presents the OR of these function buttons as one button press to the computer.  
         [0049]    An alternate arrangement of the sensor and rollerbar is shown in FIG. 13. This arrangement allows the sensor  128  to focuses on the clickable rollerbar  120  from the side. The rollerbar  120  is formed as described above, but is not cantilevered from a mount. Rather, the rollerbar  120  is supported by a U-shaped bracket  122  held to the base  130  at the front  132  of the enclosure  56 . The ends  136 ,  138  of the bracket are supported on springs  124  before supporting the rollerbar  120 . The sensor  128  is focused on the side of the rollerbar  120  with the focal plane spaced in the same manner as described above. However, in this arrangement, the sensor mount  140  cannot be fixed to the base  130  of enclosure  56 . Fixed mounting with the sensor  128  focused horizontally on the rollerbar  120 , would cause the axis of rollerbar  120  to pass out of focal range when the rollerbar  120  is depressed. Therefore, a circuit board  126  is mounted on the bracket  122  and the sensor  128  is mounted on the circuit board  126 . The entire arrangement of sensor  128  and rollerbar  120  move vertically together. When a user depresses the rollerbar  120 , the springs  124  are compressed and a switch (not shown) is activated. The sensor assembly  128  moves with rollerbar  120 , staying focused on the rollerbar  120  as it is depressed.  
         [0050]    In an alternate embodiment, as shown in FIG. 14, the internal arrangement of the rollerbar assembly  200  consists of a support  202 , and a guide  204  at respective ends of the inner rod  206 . These structures  202 ,  204  may have a Teflon™, nylon, or plastic bearing surfaces, but do not necessarily incorporate one. One end of the inner rod  206  rests on a spring  208  that allows the rollerbar  210  to function as a mouse button. The tension of the spring is adjusted by a tension screw (not shown). A brace  212  at approximately the midpoint of the length of the inner roller  206  restricts the downward movement of the rollerbar assembly  210  when it is being depressed.  
         [0051]    The sensor  216  for this embodiment is mounted below the rollerbar assembly  210  aligned with the axis of the rollerbar  210  toward the end not having the spring. The sensor  216  incorporates an optical sensor  218  such as previously described. The rollerbar assembly  210  does not move out of range of the sensor  216  when the rollerbar  210  is depressed. The sensor  216  monitors rotations and translations of an outer sleeve  214  as previously described.  
         [0052]    Alternate embodiments of the rollerbar utilizable in the ergonomic positioning device  50  are illustrated in FIGS. 15A, 15B, and  15 C. Common features of these embodiments are the right-hand end of the rollerbar rod  220 , the right-hand end of the access area  224 , the left-hand end of the access area  222 , and the left-hand end of the keyboard  226 . FIG. 15A illustrates a rollerbar  230  having two different textures. Area  232  comprises a sleeve area that is accessible to the user and may have surface chosen for user convenience, such as a hard shiny texture. Area  234  comprises a sleeve area optimized for sensor tracking, with a roughly textured surface. When rollerbar  230  is clickable, an optical sensor is focussed at approximately location  236 , a rightmost location always focussed on surface  234  while allowing left and right movement of sleeve  232 / 234 .  
         [0053]    [0053]FIG. 15B illustrates a rollerbar  240  having two different diameters. Area  242  comprises a sleeve area that is accessible to the user and has a diameter and surface chosen for user convenience, such as a relatively large diameter hard shiny surface. Area  244  comprises a sleeve area optimized for compact packaging and sensor tracking. The smaller diameter of sleeve  244  limits the excess height accumulated when the sensor is placed beneath sleeve  244 , while allowing for the ergonomic benefits of the larger diameter sleeve for user access. When rollerbar  240  is clickable, an optical sensor is focused at approximately location  246 , a rightmost location always focussed on surface  244  while allowing left and right movement of sleeve  242 / 244 .  
         [0054]    [0054]FIG. 15C illustrates a rollerbar  250  adapted for a non-clicking application. When the entire sleeve  252 / 254  is uniform, the sensor can be focussed on location  256  allowing more freedom in component placement. If the split sleeves illustrated in FIGS. 15A and 15B are used, the sensor placement is constrained by the limitation that sleeve  254  must always be within focal range. However, the sensor does not have to be placed beneath the rollerbar for non-clicking applications.  
         [0055]    For rollerbars that do not click, there is greater freedom in the placement of sensor. Since the non-clicking rollerbar, does not move vertically, the sensor can be positioned at any orientation that aligns the focus with the axis of the rod. FIG. 16 illustrates that rollerbar  260  centered on rod  261 , may have a sensor mounted in orientations  262 ,  264 , or  266  as long as the focus is aligned as shown by arrows  263 ,  265 , and  267 . Intermediate positions are also possible. While sensor positions above the midline of the rod are possible, they increase the height of the rollerbar enclosure  56  disadvantageously.  
         [0056]    The ergonomic positioning device  50  has been illustrated with the rollerbar  54  positioned closest to the keyboard and function keys positioned more distant from the keyboard. It is apparent to those knowledgeable in the art, that swapping the location of rollerbar and function keys, while maintaining both in approximately the distance from the spacebar shown above, is within the art.  
         [0057]    In addition to the embodiments described above, the palm rests can be exchanged with alternate rests of a different material and/or different shape. It is within the spirit of the invention to incorporate multiple function keys in the ergonomic positioning device with some set of these function keys field configurable. A ergonomic positioning device that implements the left mouse button function only via function keys rather than via a “clickable” rollerbar is a supported alternative embodiment.  
         [0058]    Having described preferred embodiments of the invention it will now become apparent to those of ordinary skill in the art that other embodiments incorporating these concepts may be used. Accordingly, it is submitted that the invention should not be limited by the described embodiments but rather should only be limited by the spirit and scope of the appended claims.