Abstract:
The invention includes moveable magnetic devices, for use in conjunction with electronic displays associated with computers and electronic devices enable manual input devices and control devices to be joined to the display, whereby the electronic device may be controlled, inputs may be made thereto, and the electronic display may be altered in correspondence to these inputs. In one aspect, the invention includes a fader controller comprised of a longitudinally extending track having a portion thereof extending over an image area of an electronic display, and a fader cap joined to the track for longitudinal sliding translation therealong. A plurality of permanent magnets are spaced along the track, and the fader cap includes at least one electromagnet. Conductive rails extend longitudinally on the track, and the fader cap includes contacts that electrically engage the conductive rails. Some of the fader cap contacts are connected to the electromagnet(s), and at least one track interacts with one contact on the fader cap to detect the instantaneous position of the fader cap. The electromagnets are actuated to translate the fader cap distally or proximally along the track. In another aspect, the invention provides a magnetic arrangement for joining one or more controller device to a flat panel electronic display, whereby controllers such as switches, knobs, and faders (slide controllers) may be superposed on the display.

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of application Ser. No. 09/670,610, filed Sep. 26, 2000, for which priority is claimed. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to computer input devices and, more particularly, to mechanical controller devices that may be combined with computer graphic displays and/or touch screen input devices. 
     Touch screen devices have become a commonplace user interface for electronic devices, computers, and the like. Touch screens are typically combined with a display screen which is in close proximity to the touch screen or which projects images through the touch screen. Under software control, the display may present images, video, alphanumeric information, and various combinations thereof. Moreover, the display may define corresponding areas of the touch screen as control input areas, through the presentation of control command words, iconic or graphic representations of controls, or the like. Thereafter, an operator touch at an appropriate portion of the touch screen causes the software to correlate the touch position with the control command defined by the display at that position, and to act on that command. 
     It is well known in the prior art to employ controller devices in conjunction with touch screen devices and computer displays to emulate the sensation and feel of mechanical input devices, such as knobs, joysticks, and sliding (fader) controls. Such touch screen controller devices are described, for example, in the following U.S. patents issued to the present inventors: 
     U.S. Pat. No. 5,572,239, 
     U.S. Pat. No. 5,977,955, 
     U.S. Pat. No. 5,805,146, 
     U.S. Pat. No. 5,805,145, 
     U.S. Pat. No. 5,936,613, 
     U.S. Pat. No. 5,774,115. 
     There are various arrangements known in the prior art to removably secure such controller devices to a touch screen, computer display, or a superstrate placed over either of these devices. One object of the present invention is to use magnetic assemblies to adhere controller devices to flat panel displays, with or without the combined use of touch screen devices. A further object of the invention is the use of a linear magnetic drive in a fader controller to translate the fader cap under machine control, whereby automatic fader controllers may be applied to flat panel displays, touch screens, and computer displays in general. 
     SUMMARY OF THE INVENTION 
     The present invention generally comprises moveable magnetic devices for use in conjunction with electronic displays associated with computers and electronic devices. In particular, the invention enables manual input devices and control devices to be joined to an electronic display, whereby the computer or electronic device may be controlled, inputs may be made thereto, and the electronic display may be altered in correspondence to these inputs. 
     In one aspect, the invention includes a fader controller comprised of a longitudinally extending track having at least a portion thereof extending over an image area of an electronic display. A fader cap is joined to the track for longitudinal sliding translation therealong, the variable position of the fader cap corresponding to a selected input value or to a control function. The cap may be moved manually along the track to change the input value or control function. The display output may be altered by the computer or electronic appliance in response to the input/control function to comprise an interactive graphical user interface. 
     A salient feature of the fader controller is a mechanism for driving the fader cap to any position along the track. The mechanism includes a plurality of permanent magnets spaced along the track and arranged with opposite poles in close proximity. The fader cap is provided with at least one electromagnet having poles that are longitudinally opposed. A plurality of conductive rails extend longitudinally on the track, and the fader cap includes contacts that electrically engage the conductive rails. Some of the fader cap contacts are connected to the electromagnet(s), and at least one track interacts with one contact on the fader cap to detect the instantaneous position of the fader cap. 
     The power rails are selectively driven with a voltage that alternates in accordance with the fader cap position, so that the electromagnet poles interact with the permanent track magnets to translate the fader cap distally or proximally along the track. The fader cap thus may be driven automatically to any desired position along the track, whereby the computer or electronic appliance may place the fader cap any preset position. The conductive rail associated with position sensing may include a distributed resistance therealong, whereby changes in voltage on the position sensing rail may be correlated with the linear position of the fader cap. 
     In a further embodiment of the fader controller, the number of conductive rails may be reduced to two, comprised of a DC/common rail and a resistive, position sensing rail. The fader cap includes a touch sensor circuit and a processor to drive alternately each of two electromagnets in the cap, and one of the rails includes a distributed resistance that enables the system to determine the instantaneous position of the fader cap. 
     In another aspect, the invention provides a magnetic arrangement for joining one or more controller device to a flat panel electronic display, whereby controllers such as switches, knobs, and faders (slide controllers) may be superposed on the display. The controllers may be connected to the computer or electronic appliance that is associated with the display to enable input functions and control functions to be carried out. The flat panel display output may be altered by the computer or electronic appliance in response to the input/control function to comprise an interactive graphical user interface. 
     The magnetic arrangement includes, in one aspect, a pair of tracks mounted adjacent to the rear surface of a flat panel display, the tracks disposed at the side and end margins of the display. A pair of bars are slidably secured to the side tracks and end tracks, respectively, each bar spanning the rear surface of the display, and a magnet or electromagnet is secured at the intersection of the pair of bars. The bars may be translated along their respective tracks to selectively position the electromagnet at any location that corresponds to a desired location on the front surface of the flat panel display. The controller device includes a magnet (permanent or electromagnet) that is attracted to the rear electromagnet, whereby the controller is secured to the flat panel display. The controller may comprise any of the controller devices disclosed in the prior art, such as the patent application referenced above, or exemplified in the patents referenced above. 
     As a variant of this approach, a single pair of tracks may be provided at either the sides or end of the rear surface of the display, and a bar may be slidably secured to the pair of tracks. A magnet or electromagnet is slidably secured to the bar, and translation of the bar along the track combined with translation of the electromagnet along the bar enable the positioning of the electromagnet at any selected location corresponding to a desired placement of a controller device on the front surface of the display. This arrangement may be compounded by the provision of a plurality of slidable bars in adjacent relationship, each supporting at least one electromagnet to function as described above. 
     In a further aspect, the magnetic arrangement includes an extendable, rotatable arm secured adjacent to the rear surface of a flat panel display. The arm includes a proximal end secured at one corner of the display, and a distal end which supports an electromagnet or magnet. As before, a controller device at the front surface of the display includes a magnet (permanent or electromagnet) that is attracted to the rear electromagnet, whereby the controller is secured to the flat panel display. The arm may be rotated and extended manually, or by motors and/or linear actuators. As an alternative to the rotatable arm arrangement, a multi-segment, hinged arm may be secured at the rear surface and articulated by manual or motor means to position the electromagnet to correspond to the desired placement of a controller on the front surface of the display. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side elevation of a fader controller having a linear drive for moving the fader cap along the fader track. 
     FIG. 2 is an end elevation of the fader controller, taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a functional block diagram depicting one arrangement of magnets for the linear drive fader controller of FIG.  1 . 
     FIG. 4 is a functional block diagram depicting another arrangement of magnets for the linear drive fader controller of FIG.  1 . 
     FIG. 5 is a graphic depiction of the electromagnet polarity timing required to translate the fader cap from left to right as depicted in FIGS. 1,  3 , and  4 . 
     FIG. 6 is a graphic depiction of the.electromagnet polarity timing required to translate the fader cap from right to left as depicted in FIGS. 1,  3 , and  4 . 
     FIG. 7 is a schematic layout of the conductive rails extending along the track of the linear drive fader controller of FIGS. 1-4. 
     FIGS. 8A and 8B are schematic views of the electronic circuit for operating the linear drive mechanism of the embodiment of FIGS. 1-4. 
     FIG. 9 is a flow chart depicting the general operation of the fader cap microprocessor of the circuit of FIG.  8 . 
     FIG. 10 is a flow chart depicting the general operation of the main microprocessor of the circuit of FIG.  8 . 
     FIG. 11 is a cross-sectional side elevation depicting a further embodiment of the invention, in which a controller is secured to a display using a magnet behind the display. 
     FIG. 12 is a cross-sectional side elevation depicting another embodiment of the invention, in which a controller is secured to a display using a magnet behind the display. 
     FIG. 13 is a rear elevation of the present invention, showing one embodiment for supporting moving magnets at the rear surface of a display. 
     FIG. 14 is a rear elevation of the present invention, showing another embodiment for supporting moving magnets at the rear surface of a display. 
     FIG. 15 is a rear elevation of the present invention, showing a telescoping pivoting arm for supporting a moving magnet at the rear surface of a display. 
     FIG. 16 is a rear elevation of the present invention, showing an articulated arm for supporting a moving magnet at the rear surface of a display. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention generally comprises moveable magnetic devices for use in conjunction with electronic displays associated with computers and electronic devices. With regard to FIGS. 1 and 2, one moveable magnetic device comprises a fader controller  21  that embodies the capability to be automatically moved to a preset value or predetermined position. The fader controller  21  includes a track  22  extending longitudinally and having a base surface  23  that is adapted to be secured to an electronic graphic display, such as a flat panel display, VDT, or the like. The track is provided with a T-shaped cross section, with the base surface  23  comprising the lower surface of the stem of the T section. (A fader cap  24  is secured to the track  22  for free sliding translation Ad therealong. The fader cap  24  includes low friction bearing surfaces that engage the upper, lower, and side surfaces of the upper portion of the T shape of the track to enable free translation. Other track cross-section configurations are possible, with concomitant modifications of the fader cap to engage the track in freely sliding fashion. The cap  24  may be provided with a dished upper surface  26  configured to accept a fingertip touch, so that the cap may be moved manually along the track to any desired position. 
     Secured with the track  22  is a plurality of permanent magnets  27 . The magnets  27  are arrayed with their north/south polar axes in alignment with the longitudinal extent of the track, and with confronting ends of the magnets having opposite polarity. The magnets  27  are disposed closely adjacent to the upper surface of the track  22 , so that the magnetic fields intersect the fader cap to a maximum extent. 
     Disposed within the fader cap is at least one pair  31  of electromagnets, depicted with poles A and B spaced apart along a longitudinal axis. The electromagnet(s) is arranged to be selectively driven to reverse polarity, whereby the poles A and B of the electromagnet  31  will interact with the permanent magnets  27  in the track  22  and generate longitudinal force that drives the fader cap  24  to translate along the track. Alternatively, as shown in FIG. 4, a plurality of electromagnets  31  may be disposed in the fader cap with a longitudinal spacing that is similar to the spacing provided in the embodiment of FIG.  3 . 
     The track further includes a plurality of conductive rails  32 , as shown in FIG. 7, that extend longitudinally along the track  22 . The rails may be placed on any of the track surfaces that are engaged by the fader cap. The fader cap is provided with a plurality of brushes or contacts that are disposed to extend to and electrically engage the conductive rails  32 . In this embodiment, the rails  32   a  and  32   b  are connected, respectively, to A and B current supplies, rail  32   c  is connected to Common (ground), and rail  32   p  is a Position rail, which may comprise a distributed resistance or other similar property for use in a subsystem for determining the position of the fader cap  24  along the track  22 . 
     With regard to FIG. 8A, the invention includes a driver circuit  33  for operating the electromagnet  31  to translate the fader cap. The circuit  33  includes a microprocessor  34  programmed appropriately to receive inputs and produce outputs as described herein. The microprocessor is connected to actuate driver  36 , which is connected through rail  32   a  to electromagnet  37 , and also connected to actuate driver  38  which is connected through rail  32   b  to electromagnet  39 . Both electromagnets are connected to common through rail  32   c . Either driver  36  or  38  is driven alternately to switch the polarity of the magnets  37  and  39 . It may be appreciated that the electromagnets may comprise a single unit that is driven selectively to reversible polarity by the circuit  33 . In addition, the position track  32   p  is connected to common to form a variable resistance determined by the position of the fader cap along the track. The variable resistance is connected in parallel with a fixed resistance  41 , the parallel combination being connected through an A/D converter  42  to the microprocessor  34 , which correlates the digital resistance signal from converter  42  with fader cap position, either by use of a lookup table or a subroutine that calculates position from resistance level. The circuit  33  may be embodied within the fader cap itself, or may be disposed at the margin or periphery of a display of a computer or electronic appliance to which the fader controller  21  is connected. Alternatively, the circuit  33  may be embodied in the computer system which controls such a display. 
     With regard to FIG. 5, there is shown the sequence for actuating the polarity of electromagnets A and B in north, south, or off polarity to translate the fader cap from right to left as depicted in FIGS. 1-4. Likewise the chart of FIG. 6 shows the sequence actuating the polarity of electromagnets A and B in north, south, or off polarity to translate the fader cap from left to right. These sequences are also applicable for the multiple electromagnet embodiment of FIG.  3 . It may be appreciated that the computer or electronic appliance to which the circuit of FIG. 8 is connected may selectively actuate the fader cap linear drive to translate the fader cap  24  to any desired position or preset value along the track  22 . Likewise, the graphic presentation on the display associated with the fader controller  21  may be changed to indicate (numerically or graphically) the instantaneous position of the fader cap  24  and the position or value associated therewith. 
     With reference to FIG. 8B, the fader controller  21  may includes only two conductive rails  32   r  and  32   v , a reduction in number from the four rails described previously. This embodiment may have particular utility in fabricating small models of the invention, wherein the width of the track  22  is rather narrow. Conductive rail  32   r  is connected to a current source  52 , and includes a distributed resistance to serve as a position indicator. Rail  32   v  is connected to common or ground. An onboard circuit  51  is mounted within the fader cap  22 , and is connected between the rails  32   r  and  32   v  to receive power therefrom. The circuit is arranged to move the fader cap to any selected position along the track, and to permit manual movement of the fader cap  22  to any desired position. 
     The circuit  51  includes a microprocessor  53  connected to a zener regulated power supply  54  to receive a constant operating voltage. A touch sensor circuit  56  is provided in the top surface of the fader cap  24 , and includes a signal line connected to an input of the microprocessor  53  to conduct a touch signal thereto. Another microprocessor input is formed by the output of voltage comparator  57 , which has inputs connected across a resistor network that is spanned by switch  58 . A trio of single throw, double pole switches  61 ,  62 , and  63  are connected to electromagnet A, Common, and electromagnet B, respectively, and the switches are normally closed to ground. Each switch  61 - 63  has a normally open pole connected to current source  64 , and an input triggers of switches  58  and  61 - 63  are connected to respective outputs of the microprocessor  53 , whereby they are individually, selectively actuated. 
     Whenever the touch sensor circuit  56  is activated by fingertip touch, and the touch is then removed, the circuit  56  signals the microprocessor  53 . The microprocessor  53  in turn actuates switch  58  for a short period; e.g., 1 msec. Switch  58  when closed shorts across its parallel resistor, and causes a momentary drop in the voltage on rail  32   r . This signal pulse appears at Vx, which is passed by normally closed contacts of switch  67  to A/D converter  68  and thence to main microprocessor  66 , which in turn controls the electronic graphics display and associated audio control. Thus the computer or electronic appliance is signaled whenever the fader cap  24  is touched. 
     It is noted that when the fader cap  24  is disposed in its most proximal disposition, typically withdrawn to or beyond the margin of an electronic graphic display, the resistance value of the distributed resistance in rail  32   r  is substantially zero. The voltage Vx is thus a maximum, generally equal to the voltage across the zener diode connected between supply and ground. When the fader cap  24  is disposed at its most distal position, typically extended into the image area of an electronic graphic display, the value of the distributed resistance is maximum (on the order of 10 ohms), and the voltage Vx drops to a known minimum level. Between these maximum and minimum levels, it is clear that the steady state of voltage Vx is directly indicative of the position of the fader cap  24  along the track. Thus the main microprocessor  66  may determine the position of the fader cap at any instant. 
     The main microprocessor  66  may also send data and commands to the fader cap microprocessor  53 . The microprocessor  66  may command the switch  67  to close, connecting the normally open contact to single pole, double throw switch  71 . Switch  71  is actuated by the microprocessor  66 , with the switch poles connected to differing plus voltage levels (such as 4 vdc and 5 vdc). The switch  71  may be toggled selectively to generate a pulse train of low-going pulses on the rail  32   r . These low-going pulses appear across voltage comparator  57 , which responds by generating a data packet signal that is fed to the microprocessor  53 . Thus the main microprocessor may determine the fader cap position and receive touch signals therefrom, and may also send data and commands to the fader cap. 
     With reference to FIG. 9, the functional flow chart for the microprocessor  53  begins at Mode  1 , and it first determines if there is a touch sense signal. If so, the microprocessor  53  deactivates switches  61 - 63  to turn off the electromagnets A and B. At the end of touch signal, the microprocessor sends an end of touch pulse to the main microprocessor  66 , as described above, and returns to Mode  1 . If there is no touch signal received, the system looks for a data packed received from the main microprocessor  66  (by a process described above). The data packet may include such items as a new desired position, the number of pulses that must be fed to the electromagnets to move to the new position, the speed at which the cap is to move, and the direction the cap is to move. If there is a data packet, the system generates commands to move the cap in accordance with the data packet. If no data packet has been received, the system returns to Mode  1  and begins a new loop excursion. 
     With reference to FIG. 10, the functional flow chart for the microprocessor  66  begins at Mode  1 , and it first determines if there is an end of touch signal transmitted from the fader cap circuit, as described above. If so, the microprocessor  66  reads the voltage Vx to determine the cap position along the A track  22 , and it changes the electronic display graphics and audio control in accordance with the new cap position. If there is no end of touch pulse, the system looks for a cap move request. If there is a cap move request, the system sends a data packet to microprocessor  53 , which then carries out the instructions as shown in FIG.  9 . If there is no cap move request, the flow chart returns to Mode  1  and reiterates. 
     Thus manual positioning of the fader cap is recognized by the system as a command to change a control input and its associated graphic representation on the electronic display. The system may also move the fader cap under machine control to a preset or predetermined position and associated control input value. This latter function is very useful; e.g., in a situation in which a plurality of inputs are involved, and it is desirable to establish a previous arrangement of control levels. 
     There are other equivalent means and methods for carrying out some of the functions described with respect to the embodiments of FIGS. 1-10. For example, data packets may be exchanged between the fader cap circuit  51  and the computer or electronic appliance by low power radio signal, optical signal., or the like. In addition, if the device used in conjunction with a touch screen device, the position of the fader cap may be determined by a touch signal generated by the fader cap circuit and/or provoked by a touch stylus extending from the fader cap. Furthermore, photovoltaic cells may be disposed in the fader cap to receive light from the electronic display, whereby not only operating power for the fader cap circuit may be provided, but also position sensing graphical data may be supplied to the fader cap. Likewise, the fader cap circuit may be provided with a battery power supply. Thus there are various arrangements, including those shown in the U.S. patents referenced above and in the parent application referenced above, that may obviate the need for some or all of the conductive rails described herein for powering the fader cap and transmitting position information and movement commands. And, despite the seeming complexity of these embodiments described thus far, they may be produced as small format, crack-and-peel assemblies (described in the parent application) that are inexpensive and easily placed on or removed from an electronic display, touch screen, superstrate, or the like. 
     In a further aspect of the invention, the track structure  22  on the display, touch screen, or superstrate may be eliminated. With regard to FIGS. 11 and 12, a flat panel display  81  is provided with a cover glass or superstrate  82 . Disposed below the display  81  is a structural assembly  83  that supports a magnet  84 . The magnet  84  may be permanent or electromagnetic, and is mounted for sliding translation on the assembly  83 . Disposed at the outer surface of the superstrate  82  (or at the outer surface of the display  81 , if no superstrate is provided) is a fader cap controller  86  which includes a magnet  87  (permanent or electromagnetic) that engages the magnet  83  with sufficient force to retain the fader cap controller  86  at the outer surface of the display/superstrate assembly. In the embodiment of FIG. 11, the fader cap controller is received in a channel-like groove in smoothly sliding fashion, whereby translation of the cap is guided in a linear direction. In the embodiment of FIG. 12, the fader cap  86  is slidably received on the surface of the superstrate or flat panel display, and is guided manually in accordance with a graphic presentation on the flat panel display. In either case, the magnet  84  is adapted to undergo translation in concert with the fader cap  86 , so that adhesion to the display assembly is maintained. The sliding surface of the cap  86  may comprise a polished material such as metal or glass, a lubricious substance such as Teflon, or a cushioning material such as felt or any other material that slides easily over the front surface of the display assembly. 
     With regard to FIG. 13, one embodiment of the structural assembly  83  includes a pair of rails  91  secured to the rear surface of a flat panel display  92  and spaced apart to be outside the side margins of the image area  93  of the display  92 . Another pair of rails  93  are secured to the rear surface of the display  92  outside the end margins of the image area  93 . A bar  94  is slidably mounted on the rails  91 , and another bar  96  is slidably mounted on the rails  95 . At the intersection of the bars  94  and  96  a magnet  97  (electromagnet or permanent magnet) is secured. The bars  94  and  96  may be fabricated of transparent material, particularly for back-lighted displays. Translation of the bars  94  and  96  in rectilinear format is carried out to position the magnet  97  at any desired location behind the display, corresponding to any desire location of a magnetically adhered controller device on the front surface of the display assembly. In addition, the position of the magnet  97  may move in concert with the movement of the controller at the front surface, under control of the microprocessor that operates the display assembly and associated computer or electronic appliance. 
     In a further embodiment of the invention, shown in FIG. 14, a pair of rails  101  are secured to the rear surface of a flat panel display  102  outside the end margins of the image area  103 . At least one, and preferably a plurality of bars  104  are slidably mounted on the rails  101 , spanning the image area  103  and each supporting a magnet  106  (electromagnet or permanent magnet). Each magnet  106  is individually translatable along its respective bar  104 , whereby a plurality of magnets  106  may be arrayed behind the display to support a like plurality of magnetically adhered controller devices throughout the image area  103 . Each bar  104  may be translated along the rails  101  under machine control, and each magnet  106  may be translated under machine control along its respective bar  104 . Thus, for example, a plurality of fader cap controllers (or knob controllers described in related patents and applications) capable of magnetic adhesion may be placed or scattered on the front surface of the display  102 , and adhered to respective magnets  106 . Changes in positions of the fader cap controllers are detected by the microprocessor that operates the display and its associated computer or electronic appliance, and the positions of magnets  106  may be changed in concert to maintain magnetic adhesion. Translation of bars and magnets may be carried out using linear actuators, motor drives for pulley or rack and pinion arrangements, or any other mechanisms known in the prior art for such purposes. 
     With regard to FIG. 15, a further embodiment of the invention includes an arm  107  mounted on the rear surface of a flat panel display  108 , the arm mount enabling rotation of the arm within an angular range that circumscribes the image area  109  of the flat panel display. The arm is telescoping (extendable) and rotatable under machine control, as is commonly found in the art of robotics and related fields. At the distal end of the arm  107  is a magnet  111  (electromagnet or permanent magnet) that is capable of securing a controller device capable of magnetic adhesion to the front surface of the display assembly. The arm  107  may be rotated and extended to place the magnet  111  at any desired position in the image area  109  to secure a controller device thereat, and may be moved in concert with the controller (in the case of a fader cap controller) or may secure the controller device at a fixed location (as in the case of a knob controller). 
     A further variant of this concept, shown in FIG. 16, includes an arm assembly  112  secured to the rear surface of the display  113  outside of the image area  114  thereof. The arm assembly includes at least two segments  116  and  117  that are hinged at pivot  118 . A magnet  119  is supported at the distal end of the arm assembly  112 , and is adapted to magnetically adhere a controller device to the front surface of the display  113 . The segments  116  and  117  may be articulated using pulley and cable mechanisms, or direct drive motors at the pivot points, or other mechanisms known in the prior art. As before, the arm  112  may be rotated and extended to place the magnet  119  at any desired position in the image area  114  to secure a controller device thereat, and may be moved in concert with the controller (in the case of a fader cap controller) or may secure the controller device at a fixed location (as in the case of a knob controller). 
     With regard to the embodiments of FIGS. 11-16, it may be appreciated that the control device secured to the front surface includes a magnetic member that may comprise a mass of ferromagnetic material, a permanent magnet, or an electromagnet, any of which may be configured or polarized to optimize engagement with the magnetic device disposed at the rear surface of the flat panel display. 
     The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in light of the above teaching without deviating from the spirit and the scope of the invention. The embodiment described is selected to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as suited to the particular purpose contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.