Abstract:
A tilter assembly is provided for positioning an electronic device such as a flat panel display. The tilter assembly includes a tilter shaft holder having an opening aligned along an axis and a shaft received within the opening. The shaft is rotatable about the axis, and may be coupled to a support. The tilter shaft holder is coupled to the electronic device. The tilter assembly also includes a spring device in operative association with the shaft to provide a bias or counterbalance to the electronic device, thereby preventing undesired rotation about the axis.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a tilter apparatus for positioning electronic devices. More particularly, the present invention relates to a tilter apparatus having a bias assembly for adjustably positioning an electronic device such as a flat panel display.  
           [0002]    In the past people have placed video monitors and other electronic equipment on desks, tabletops, or upon other equipment such as personal computers or workstations. One drawback to these configurations is the reduction in available workspace taken up by the equipment. Another drawback is the inability to place the equipment in a desired location. A further drawback is the potential for eye strain, neck strain and/or a cumulative trauma disorder such as carpel tunnel syndrome from poor placement of devices such as monitors and keyboards.  
           [0003]    Different solutions have been provided in order to overcome these obstacles. For example, in one solution, a monitor stand or printer stand elevates the apparatus over other equipment on a desk. While this may free up workspace, it often places the equipment in an undesirable location. Another solution employs a mechanical extension arm to support the monitor. Extension arms free up workspace and allow users to place the equipment where it is wanted. One such extension arm is shown and described in U.S. Pat. No. 6,478,274, entitled “Arm Apparatus for Mounting Electronic Devices,” which is fully incorporated by reference herein. Another type of extension arm is shown and described in U.S. Pat. No. 6,409,134, entitled “Arm Apparatus For Mounting Electronic Devices With Cable Management System,” which is fully incorporated by reference herein.  
           [0004]    These extension arms may attach to a workspace and provide for substantial freedom of movement of the monitor or other equipment near the workspace. However, in many cases it is not desirable to tie the extension arm to the workspace itself. In these situations, the extension arm may be mounted to a wall near the workspace using a wall mount assembly. In the past, such assemblies have used a single mounting piece that connects to the extension arm and attached to the wall. Unfortunately, this design may be unable to manage heavy or bulky loads, e.g., large screen monitors. Thus, there is a need for a wall mount assembly capable of handling these kinds of loads.  
           [0005]    It is often desirable to obtain additional freedom of movement beyond that provided by the extension arm. A tilting device can be used to accomplish this goal. The tilting device connects between the extension arm and the equipment, allowing the equipment to rotate about one or more axis. One such tilting device is shown and described in U.S. Pat. No. 6,505,988, entitled “Tilter for Positioning Electronic Devices,” which is fully incorporated by reference herein. However, existing tilter devices may not be fully compatible with heavy and/or bulky equipment, such as large screen monitors. Therefore, a need exists for tilting devices to address this concern.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with an embodiment of the present invention, a tilting device is provided. The tilting device includes an adapter plate and a tilter assembly. The adapter plate is adapted for attaching to a device. The tilter assembly includes a tilter shaft holder, a shaft, an arm mount, a tilter arm and a spring. The tilter shaft holder has a first opening therein and is coupled to the adapter plate. The first opening is aligned along an axis. The shaft is received within the first opening so as to be rotatable about the axis. The arm mount is coupled to the shaft and is adapted to engage a support. The tilter arm has a first end coupled to the shaft and a second end remote from the first end. The tilter arm is adapted to rotate about the axis upon rotation of the shaft. The spring has a first end connected to the adapter plate and a second end connected to the second end of the tilter arm. The spring is operable to provide counterbalance to the device. A bushing may be received within the first opening in the tilter shaft holder so as to receive the shaft. A locking mechanism may be provided to engage the tilter shaft holder and restrict rotation about the axis.  
           [0007]    Preferably, the spring comprises a plurality of springs connecting the adapter plate to the second end of the tilter arm. In an alternative, at least of one of the plurality of springs is removable. In another example, the arm mount is inserted through the shaft substantially perpendicular to the axis. When the bushing is provided, the tilting device may include a set screw adapted to threadedly engage the tilter shaft holder and restrict rotation about the axis. In this case, the tilter shaft holder and the bushing may each have a slot disposed along the axis. When the set screw fully engages the tilter shaft holder, the tilter shaft holder slot and the bushing slot are compressible to restrict rotation about the axis. In an alternative, the tilter shaft holder slot extends the entire length of the tilter shaft holder. In another alternative, the bushing slot extends the entire length of the bushing.  
           [0008]    In a further alternative, the tilter shaft holder comprises a pair of tilter shaft holders and the bushing comprises a pair of bushings received within the pair of tilter shaft holders. A first one of the pair holders may be disposed at a first end of the shaft and a second one of the pair of tilter shaft holders may be disposed at a second end of the shaft. Optionally, the tilting device further comprises a retaining ring adapted to engage an end of the bushing and to prevent movement of the bushing along the axis. If the retaining ring is provided, the tilter device preferably includes a cap to engage the end of the tilter shaft holder and covering the retaining ring and the bushing. In another alternative, the tilter shaft holder is coupled to the adapter plate by at least one screw. In yet another alternative, the second end of the tilter arm is angled so that the tilter arm does not interfere with the action of the spring. Preferably, in this case, the second end of the tilter arm is J-shaped.  
           [0009]    In accordance with another embodiment of the present invention, a tilting device for adjustably mounting an electronic device is provided. The tilting device comprises a tilter shaft holder, a shaft, an arm mount, a tilter arm, a spring, and means for coupling the tilting device to the electronic device. The tilter shaft holder has an opening aligned along an axis. The shaft is received within the opening and is rotatable about the axis. The arm mount is coupled to the shaft and is adapted to engage a support. The tilter arm has a first end coupled to the shaft and a second end remote from the first end. The tilter arm is rotatable about the axis upon rotation of the shaft. The spring is in operative engagement with the tilter arm and the means for coupling so that the spring provides counterbalance to the electronic device.  
           [0010]    Preferably, the tilter device further comprises a means for restricting rotation of the tilting device about the axis. More preferably, the means is a set screw adapted to threadedly engage the tilter shaft holder. In another alterative, the tilting device further comprises a bushing received within the opening of the tilter shaft holder. In this case, the shaft is received within the bushing. More preferably, the tilter shaft holder comprises a pair of tilter shaft holders and the bushing comprises a pair of bushings received within the pair of tilter shaft holders. In a further alternative, the tilting device includes a set screw adapted to threadedly engage the tilter shaft holder while restricting rotation of the tilting device about the axis. In this case, the tilter shaft holder and the bushing each have a slot disposed along the axis. When the set screw fully engages the tilter shaft holder, both the tilter shaft holder slot and the bushing slot are compressible to restrict rotation about the axis. In a further alternative, the spring comprises a plurality of springs. In this case, at least one of the plurality of springs may be removable.  
           [0011]    In accordance with a further embodiment of the present invention, a tilting device having an adapter plate and a tilter assembly is provided. The adapted plate is for attaching to a device. The tilter assembly includes a tilter shaft holder, a shaft, an arm mount and a torsion spring. The tilter shaft holder is coupled to the adapter plate and has a first opening aligned along an axis. The shaft is received within the first opening so as to be rotatable about the axis. The arm mount is coupled to the shaft and is adapted to engage a support. The torsion spring is received within the shaft, and resists rotation of the shaft about the axis and provides counterbalance to the device.  
           [0012]    In an alternative, the tilting device further comprises a locking mechanism for engaging the tilter shaft holder. In this case, the locking mechanism is adapted to prevent rotation about the axis. Preferably, the locking mechanism is a set screw adapted to further engage the tilter shaft holder. In another example, the tilting device further comprises a bushing received within the first opening in the tilter shaft holder. In this case, the shaft is received within the bushing. Preferably, the tilter shaft holder includes a pair of tilter shaft holders and the bushing includes a pair of bushings received within the pair of tilter shaft holders. More preferably, a first one of the pair of tilter shaft holders is disposed at a first end of the shaft, and a second one of the pair of tilter shaft holders is disposed at a second end of the shaft. In further alternative, the tilting device further comprises a set screw adapted to threadedly engage the tilter shaft holder in order to restrict rotation about the axis. In this case the tilter shaft holder and the bushing each preferably have a slot disposed along the axis. When the set screw fully engages the tilter shaft holder, both the tilter shaft holder slot and the bushing slot are compressible to restrict rotation about the axis. In further alternative, the tilting device further includes a tension mechanism for pre-tensioning the torsion spring. The tension mechanism preferably includes a body portion that is insertable into the torsion spring. Optionally, the tension mechanism includes at least one boss and the tilter shaft holder includes at least one recess. After pre-tensioning, the boss is inserted into the recess such that the torsion spring is securely received in the shaft. More preferably, the Boss and the recess are square-shaped. In another alternative, the torsion spring includes a first tang at a first end. The first tang is operable to engage the shaft. More preferably, the first tang protrudes from the torsion spring to engage an opening in the shaft. In a further alternative, the tilting device further comprises a plug. In this case, the torsion spring further includes a second tang at a second end of the torsion spring. The plug is adapted to engage the second tang and the tilter shaft holder. Preferably, the plug includes at least one boss and the tilter shaft holder includes at least one recess for receiving the boss.  
           [0013]    In accordance with yet another embodiment of the present invention, a tilting device for adjustably mounting an electronic device is provided. The tilting device includes a tilter shaft holder, a shaft, an arm mount, a torsion spring and a means for coupling the tilting device to the electronic device. The tilter shaft holder has an opening aligned along an axis. The shaft is received within the opening and is rotatable about the axis. The arm mount is coupled to the shaft and is adapted to engage a support. The torsion spring is received within the shaft and resists rotation of the shaft about the axis and provides counterbalance to the electronic device.  
           [0014]    In an alternative, the tilting device further comprises a means for restricting rotation of the tilting device about the axis. Preferably, this means is a set screw adapted to threadedly engage the tilter shaft holder. In another alternative, the tilting device preferably further comprises a bushing received within the opening of the tilter shaft holder. In this case, the shaft is received within the bushing. More preferably, the tilting device further includes a set screw adapted to further engage the tilter shaft holder in restricting rotation of the tilting device about the axis. In this situation, the tilter shaft holder and the bushing each have a slot exposed along the axis. When the set screw fully engages the tilter shaft holder, both the tilter shaft holder slot and the bushing slot compress so that rotation about the axis is restricted.  
           [0015]    In accordance with another embodiment of the present invention, a tilting device is provided. The tilting device includes an adapter plate, a tilter shaft holder, a shaft and a spring device. The adapter plate is for attaching to a device. The tilter shaft holder is coupled to the adapter plate and has an opening aligned along an axis. The shaft is received within the opening so as to be rotatable about the axis. The spring device is in operative relation to the shaft, wherein the spring device is adapted to provide counterbalance to the device.  
           [0016]    In an alternative, the spring device operatively engages the adapter plate and the shaft. In another alternative, the spring device is received within the shaft. In a further alternative, the tilting device further comprises a bushing received within the opening. In this case, the shaft is received within the bushing.  
           [0017]    In accordance with a further embodiment of the present invention, a tilter assembly for counterbalancing a device is provided. The tilter assembly comprises a tilter shaft holder, a shaft and a spring device. The tilter shaft holder has a first opening aligned along an axis. The shaft is adapted to be coupled to a support. The shaft is received within the first opening for rotation about the axis. The spring device is in operative association with the shaft for counterbalancing the device when attached to the tilter assembly. In one alternative, the spring device comprises a torsion spring received within the shaft. The torsion spring resists rotation of the shaft about the axis and provides counterbalance to the device. The tilter assembly may also include a tension mechanism for pre-tensioning the torsion spring. In this case, the tension mechanism preferably includes a boss and the tilter shaft holder preferably includes a recess. After pre-tensioning, the boss is inserted into the recess such that the torsion spring is securely received within the shaft. In another alternative, the spring device comprises a tilter arm and a spring. The tilter arm has a first end coupled to the shaft and a second end remote from the shaft. The tilter arm is adapted to rotate about the axis upon rotation of the shaft. The spring has a first end operatively coupled to the device and a second end connected to the second end of the tilter arm. The spring is operable to provide counterbalance to the device. Preferably, the spring comprises a plurality of springs. More preferably, at least one of the springs is removable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 illustrates a rail-mounted extension arm assembly connected to a tilting device for adjustably mounting an electronic device in accordance with an embodiment of the invention.  
         [0019]    [0019]FIG. 2 illustrates a detailed view of the extension arm of FIG. 1.  
         [0020]    [0020]FIG. 3 illustrates a view of a rail mounting assembly in accordance with an embodiment of the present invention.  
         [0021]    FIGS.  4 A-C illustrate several views of the rail mounting assembly in accordance with an embodiment of the invention.  
         [0022]    FIGS.  5 A-B illustrate views of upper and lower mounts of a rail mounting assembly in accordance with an embodiment of the invention.  
         [0023]    FIGS.  6 A-B illustrate perspective views of a tilter device in accordance with an embodiment of the invention.  
         [0024]    [0024]FIG. 7 is an exploded assembly drawing of a tilter assembly in accordance with an embodiment of the invention.  
         [0025]    FIGS.  8 A-B illustrate a tilter shaft holder in accordance with an embodiment of the invention.  
         [0026]    FIGS.  9 A-C illustrate a tilter arm in accordance with an embodiment of the invention.  
         [0027]    [0027]FIG. 10 is an exploded assembly drawing of a torsional tilter assembly in accordance with another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0028]    The aspects, features and advantages of the present invention will be appreciated when considered with reference to the following description of preferred embodiments and accompanying figures. In describing the preferred embodiments of the invention illustrated in the figures, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each term selected includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.  
         [0029]    [0029]FIG. 1 illustrates an extension arm  100  engaged at one end to a rail mount  200  and attached to a tiling device  300  at the other end. The rail mount  200  may be affixed to a wall or other substantially flat surface. The features of the rail mount  200  will be explained in more detail below with regard to FIGS. 3-5. The tilting device  300  is adapted to attach to an electronic device, and provides a bias or counterbalance so that the electronic device can be readily maintained in a desired position. While the electronic device is described below as a flat screen monitor or other video monitor, the invention is not limited to use with such devices, and may be used with a wide variety of equipment. The features of the tilting device  300  will be explained in more detail below with regard to FIGS. 6-10.  
         [0030]    The extension arm  100  may be a conventional extension arm, and will now be described generally with reference to FIG. 2. Preferably, the extension arm  100  is one of the types fully described in above-referenced U.S. Pat. Nos. 6,409,134 and 6,478,274. As shown in FIG. 2, the extension arm  100  includes a first endcap  102 , an arm  120 , a second endcap  130  and a forearm extension  140 .  
         [0031]    The first endcap  102  includes a housing  104  attached to one end of the arm  120  by, for example, pins  106 . At least one shaft  108  is adapted for connection to the rail mount  200 . Preferably, the shaft  108  comprises a lower shaft  108   a  and an upper shaft  108   b  separately engaged to the housing  104 . One or both of the lower shaft  108   a  and the upper shaft  108   b  may be integrally molded with an endwall of the housing  104 . Alternatively, one or both of the lower shaft  108   a  and the upper shaft  108   b  may be secured to the housing  104  by sleeves  110 . In this case, the sleeves  110  may be affixed to the top and bottom endwalls of the housing  104  by screws  112 . The shaft  108  may be covered at either end by top hat plugs  114  to enhance the visual appearance.  
         [0032]    The arm  120  is preferably formed of an upper housing  122  and a lower housing  124 . The upper housing  122  and the lower housing  124  define a chamber therebetween containing, e.g., a gas spring (not shown). The gas spring is preferably adjustably mounted at one end within the first endcap  102  and at the other end to, e.g., a ball stud mounted within the upper housing  122 . As shown in FIG. 2, the arm  120  may include one or more external cable ties  126  in order to secure the cable of an electronic device supported by the extension arm  100 . Alternatively, the cable may be secured within the arm  120  as shown and described in U.S. Pat. No. 6,409,134.  
         [0033]    The second endcap  130  has a housing  132  attached to the second end of the arm  120  by, for example, pins  106 . A shaft  134  preferably extends out of the top of the housing  132  and connects to the forearm extension  140 . The forearm extension  140  includes a body  142  having channels  144  and  146  at each end thereof. The shaft  134  is received within the channel  146 , and the forearm extension  140  is rotatable about the shaft  134 . A bushing  160  may be received within the channel  144 . The tilting device  300  can be inserted into the bushing  160 , and is rotatable within the channel  144 . The forearm extension  140  preferably has a locking mechanism for restricting movement of the tilting device  300  within the channel  144 . The locking mechanism may be a set screw  148  that is insertable into a wall of the channel  144 . When the set screw  148  is tightened, it causes the bushing  160  to flex inward and frictionally engage the tilting device  300  and thus prevent the tilting device  300  from rotating within the channel  144 .  
         [0034]    The upper channel  122 , the lower channel  124 , the first endcap  102  and the second endcap  130  are configured so as to form an adjustable parallelogram. When configured, the housing  104  of the first endcap  102  and the housing  132  of the second endcap  130  point in opposite directions. The shape of the parallelogram is retained by the gas spring within the chamber of the arm  120 . Generally, the gas spring is sized so as to have a fixed length until an upward or downward force is exerted at the second endcap  130  that exceeds the gas spring&#39;s designed resistance. Thus, the gas spring retains the parallelogram shape when the only force exerted at the second endcap  130  is the weight of the flat screen device. However, the gas spring permits the parallelogram shape to be adjusted when a user pushes the flat screen device, which is preferably coupled to the forearm extension  140  by means of the tilting device  300 , up or down.  
         [0035]    Referring back to FIG. 1, it can be seen that both the upper shaft  108   b  and, the lower shaft  108   a  are engaged with the rail mount  200 . FIG. 3 illustrates the rail mount  200  in more detail. The rail mount  200  includes a wall mount  202 , a lower mount  220  and an upper mount  250 . The wall mount  202  may be formed of a metal or other suitable material. The wall mount  202  includes a pair of opposing, parallel rails  204 , which define an elongated opening to receive the lower mount  220  and the upper mount  250 . An axis A is defined along a line between the rails  204 . The shafts  108   a,b  of the first endcap  102  are pivotal about the axis A, as will be described below. The wall mount  202  may have one or more holes  206  adapted to receive fasteners for attaching the wall mount  202  to a surface. While the holes  206  are shown in FIGS.  4 A-C spaced along the axis A between the rails  204 , the holes  206  may be located in any position on the wall mount  202 . Preferably, the holes  206  are located so that they are not covered by or interfere with placement of the lower mount  220  and the upper mount  250 . As seen in FIGS.  4 A-C, the wall mount  202  may also include holes  208  for attaching the upper mount  250 , as will be explained below.  
         [0036]    It can be seen in FIGS. 4B and 5B, that the lower mount  220  includes a body  222 , a “T” structure  224 , and flanges  226 . The body  222  includes a central opening  230 , which would be aligned along the axis A. The central opening  230  is adapted to receive a bottom bushing  232  as seen in FIG. 3. The bottom end of the lower shaft  108   a  of the first endcap  102  is insertable into the bottom bushing  232 . The bottom bushing  232  provides a bearing surface upon which the bottom end of the lower shaft  108   a  may rotate. Preferably, the bottom bushing  232  is made of plastic, providing a smooth surface that minimizes friction and avoids metal-to-metal contact between the lower shaft  108   a  and the body  222 . Moreover, a lip  246  of the bottom bushing  232  (FIG. 4B) preferably protrudes from the central opening  230  and acts as a washer between the lower sleeve  110  of the first endcap  102  and the body  222 . This again minimizes friction, and avoids metal-to-metal contact. The bottom bushing  232  may comprise separate pieces  232   a  and  232   b , as shown in FIG. 4B. The piece  232   a  preferably includes the lip  246 . The separate pieces  232   a  and  232   b  may be press fit into the central opening  230 .  
         [0037]    As seen in FIG. 3, the T structure  224  is insertable into the rails  204 , and the flanges  226  ride over the rails  204 . The T structure  224  and the flanges  226  are structured to engage opposite faces of the rails  204 . Thus, the lower mount  220  can slideably engage the rails  204  along the axis A. The lower mount  220  may be removably or permanently affixed to the wall mount  202 . As shown in FIG. 4A, the lower mount is preferably permanently attached to the wall mount  202  by welding the T structure  224  to the body of the wall mount  202  and/or by welding the flanges  226  to the rails  204 .  
         [0038]    Returning to FIG. 3, a wrapper  236  may cover the body  222 . The wrapper  236  may be, for example, plastic sheeting to prevent abrasion between the arm  120  and the body  222 . The wrapper  236  may be attached to the body  222  using screws or other fasteners  238  that are insertable into holes  242 , which are shown in FIG. 5B. Alternatively, the wrapper  236  may be glued or otherwise adhered to the body  222 . The wrapper  236  may be selected based upon color, texture, durability, cost and/or other criteria.  
         [0039]    The body  222  preferably includes a locking mechanism for restricting movement of the bottom end of the lower shaft  108   a  within the central opening  230 . As shown in FIG. 4B, the locking mechanism is preferably a set screw  240  that is insertable into a hole  234  in a wall of the body  222 . When the set screw  240  is tightened, it causes the bottom bushing  232  to flex inward and frictionally engage the bottom end of the lower shaft  108   a  and thus prevent the first endcap  102  from rotating about the axis A. Alternatively, the locking mechanism may be any other mechanism, e.g., a latch, clamp, clasp or hasp, which is capable of performing the equivalent function to constrict rotation about the axis A. When the bottom bushing  232  comprise the separate pieces  232   a  and  232   b , the set screw  240  is preferably placed to cause the piece  232   a  to flex inward and frictionally engage the bottom end of the lower shaft  108   a.    
         [0040]    The upper mount  250  is illustrated by the exploded view of FIG. 5A. The upper mount  250  includes a body  252 , an extended “T” structure  254 , and flanges  256 . The body  252  includes a central opening  260 , which will be aligned with the axis A and the central opening  230  of the lower mount  220  when the upper mount  250  is inserted into the rails  204 . The central opening  260  is adapted to receive a top bushing  262 , which may be press fit therein. The top end of the upper shaft  108   b  of the first endcap  102  is insertible into the top bushing  262 . The top bushing  262  provides a bearing surface upon which the top end of the upper shaft  108   b  may rotate. Preferably, the top bushing  262  is made of plastic, providing a smooth surface that minimizes friction and avoids metal-to-metal contact between the upper shaft  108   b  and the body  252 . Moreover, a lip  276  of the top bushing  262  (FIG. 5A) preferably protrudes from the central opening  260  and acts as a washer between the upper sleeve  110  of the first endcap  102  and the body  252 . This again minimizes friction, and avoids metal-to-metal contact.  
         [0041]    As seen in FIG. 3, the extended T structure  254  is insertable into the rails  204 , and the flanges  256  ride over the rails  204 . Thus, the upper mount  250  can slideably engage the rails  204  along the axis A. The extended T structure  254  preferably includes a portion  258  that extends past the body  252 . The portion  258  preferably includes one or more holes  268  having the same size and spacing as the holes  208  of the wall mount  202 . The upper mount  250  may be removably affixed to the wall mount  202  using a retaining mechanism. For example, the retaining mechanism may be screws  272  or other fasteners inserted through the holes  268  into the holes  208  of the wall mount  202 .  
         [0042]    As seen in FIG. 3, a wrapper  266  may cover the body  252 . The wrapper  266  may be, for example, a plastic sheeting to prevent abrasion between the arm  120  of the extension arm  100  and the body  252 . The wrapper  266  may be attached to the body  252  using screws or other fasteners  258  that are insertable into holes  274 , which are shown in FIG. 5A. Alternatively, the wrapper  266  may be glued or otherwise adhered to the body  252 . The wrapper  266  may be selected based upon color, texture, durability, cost and/or other criteria.  
         [0043]    Returning to FIG. 1, it can be seen that the lower and upper shafts  108   a,b  of the first endcap  102  are securely retained by the lower mount  220  and the upper mount  250 , respectively. A user may adjust the placement of a flat screen monitor by pivoting the lower and upper shafts  108   a,b  about the axis A. Once the desired position is attained, the user can secure the shafts  108   a,b  by tightening the set screws  240  and  270  in the lower mount  220  and the upper mount  250 , respectively.  
         [0044]    As described above, the lower mount  220  need not be permanently affixed to the wall mount  202 . Instead, it is possible to adjustably position the lower mount  220  and the upper mount  250  at desired points along the axis A by removably securing the lower mount  220  and the upper mount  250  to the wall mount  202 . For example, the extended T structure  254  having the holes  268  may be used in place of the T structure  224 . In this example, the wall mount  202  may include a series of holes  208  spaced along the axis A. The user could affix the wall mount  202  to a surface, position the lower mount  220  at a desired height by selecting the appropriate pair of holes  208 , and affix the lower mount to the wall mount  202  by fastening screws  272  through the holes  268  into the selected holes  208 . Then the lower end of the lower shaft  108   a  is inserted into the central opening  230  of the lower mount  220 . The upper mount  250  is then lowered along the rails  204  until the upper end of the upper shaft  108   b  is engaged by the central opening  260  of the upper mount  250 .  
         [0045]    As shown in the figures and described above, the rail mount  200  retains the extension arm  100  and allows it to rotate about the axis A so that a user may position a flat panel monitor in a desired location. The load and the torque generated by the flat panel monitor are distributed across both the lower mount  220  and the upper mount  250 . The upper mount  250  ensures that the shafts  108   a,b  are securely retained, and allows the rail mount  200  to sustain a heavier load than situations in which only the lower mount  220  is used.  
         [0046]    The tilting device  300  is shown in detail in FIGS. 6A and 6B. It includes an adapter plate  302  and a tilter assembly  340 . The adapter plate  302  may be secured to a flat screen monitor by screws  304  inserted through slots  310 . Preferably, a lock washer  306  and a flat washer  308  are placed between the head of each screw  304  and the adapter plate  302 . A base plate pad  312  may be secured to the adapter plate  302  by one or more screws  314 . The base plate pad  312  serves to prevent abrasion of the adapter plate  302  with the arm  120 , and is preferably the same material as the wrappers  236  and  266  of the rail mount  200 . The adapter plate  302  preferably also includes one or more holes  316  along a side  318  and one or more holes  320  in a central portion  322  for securing components of the tilter assembly  340 , as will be described below.  
         [0047]    The tilter assembly  340  includes tilter shaft holders  342 , bushings  344 , a tilter shaft  346 , an arm mount  348 , a tilter arm  350 , at least one spring  352  and a locking mechanism  354 . The tilter shaft holders  342  may be affixed to the adapter plate  302  by fasteners  324  inserted through the holes  320  in the adapter plate  302  and through the holes  372  (FIG. 7) in a base portion of the tilter shaft holders  342 . As shown in FIGS.  6 A-B, two tilter shaft holders  342  engage the tilter shaft  346 , which is rotatable about an axis B. In alternate embodiments, a single tilter shaft holder  342  may engage one or both ends of the tilter shaft  346 . The tilter shaft holder(s)  342  is preferably a metal such as aluminum.  
         [0048]    The tilter shaft holder  342  is shown in more detail in the side and bottom views of FIGS.  8 A-B, respectively. A shaft opening  360  is dimensioned so as to receive the bushing  344  and the tilter shaft  346  therein. A slot  362  is provided along the sidewall of the shaft opening  360 . Preferably, the slot  362  extends the length of the shaft opening  360 . A bore  374  preferably extends through a first flange  376  into a stem  378  of the tilter shaft holder  342 . The tilter shaft holder  342  may include a second flange  380  opposite the first flange  376 . The locking mechanism  354  is preferably a set screw, and the bore  374  is preferably at least partly threaded to receive the set screw. The threads of the set screw may be coated with nylon to securely engage the set screw with the bore  374 . Alternatively, the locking mechanism  354  may be any other mechanism, e.g., a latch, clasp, hasp or clamp, which performs the equivalent function to constrict rotation about the axis B.  
         [0049]    As seen in the exploded view of FIG. 7, the bushing  344  includes a slot  364  provided along its sidewall. Preferably, the slot  364  extends the length of the sidewall of the bushing  344  such that the bushing  344  has a non-closed annular shape. The bushing  344  is preferably a metal such as bronze. The bushing  344  is inserted into the shaft opening  360 . The slot  364  of the bushing  344  need not be aligned with the slot  362  of the tilter shaft holder  342 . The tilter shaft  346  may then be inserted into shaft opening  360 .  
         [0050]    A washer  366  and a retaining ring  368  may be inserted over the tilter shaft  346  and the bushing  344 . An endcap  370  may cover this portion of the tilter assembly  340 . The endcap  370  may be a plastic plug or other suitable covering.  
         [0051]    The arm mount  348  may be inserted into the channel  144  of the forearm extension  140  (FIG. 2). As seen in FIG. 7, the arm mount  348 , in the nature of a shaft, may extend perpendicularly through the tilter shaft  346 . Preferably, both the arm mount  348  and the tilter shaft  346  are a metal such as aluminum. The arm mount  348  may be welded to the tilter shaft  346 . When the arm mount  348  is securely attached to the forearm extension  140 , the adapter plate  302  may be adjusted, rotating about the axis B until the electronic device is appropriately positioned. Then the locking mechanism  354  may be engaged by, e.g., inserting the set screw into the bore  374  and tightening to close the slot  362  and the slot  364 , as seen in FIG. 6B, to restrict motion about the axis B. A lock washer  356  and/or a protective washer  358  may separate the head of the set screw from the tilter shaft holder  342 .  
         [0052]    As seen in FIG. 9, the tilter arm  350  preferably attaches to the tilter shaft  346  by connection to an end of the arm mount  348 . The tilter arm  350  may be welded to the arm mount  348 . At the end of the tilter arm  350 , one or more holes or slots  382  are preferably provided for the springs  352  to engage. The springs  352  attach at one end to the holes  316  along the side  318  of the adapter plate  302  and attach at the other end to the holes  382  in the tilter arm  350 . One or more of the springs  352  is preferably removable, which allows the user to adjust the biasing/counterbalancing. Preferably, the end  384  of the tilter arm  350  is shaped so that tilter arm  350  does not interfere with or otherwise contact the springs  352 . As seen in the figure, the end  384  has a “J” shape to achieve this goal.  
         [0053]    The springs  352  provide a counterbalance or bias to ensure that a heavy and/or bulky electronic device does not cause the adapter plate  302  to rotate about the axis B even though the locking mechanism  354  is engaged. While a single spring  352  may be used, preferably two or more springs are employed. As seen in FIG. 6B, the springs  352  may include different kinds of springs  352   a  and  352   b , which may be selected depending upon the weight of the electronic device attached to the adapter plate  302 . The springs  352   a,b  may be selected to have different spring tensions. The springs  352  are preferably made from steel spring wire. The springs  352  may be viewed generally as a biasing device, and other devices or structures capable of providing such biasing may be using in place of or complementary with the springs  352 .  
         [0054]    In an alternate embodiment shown in FIG. 10, a tilter assembly  400  is provided having an internal torsion spring to achieve the same result as the external springs  352  and the tilter arm  350 . The tilter assembly  400  includes a tilter shaft holder  402 , a bushing  420 , a tilter shaft  430 , an arm mount  440 , a torsion spring  450 , a tension mechanism  460  and a locking mechanism  470 . The tilter shaft holder  402  may be affixed to the adapter plate  302  (FIGS.  6 A-B) by the fasteners  324  inserted through the holes  320  in the adapter plate  302  and through holes  408  in a base portion of the tilter shaft holder  402 . As shown in FIG. 10, two tilter shaft holders  402  engage the tilter shaft  430 , which is rotatable about an axis C. In alternate embodiments, a single tilter shaft holder  342  may engage one or both ends of the tilter shaft  346 . The tilter shaft holder(s)  402  is preferably a metal such as aluminum.  
         [0055]    A shaft opening  404  is dimensioned so as to receive the bushing  420  and the tilter shaft  430  therein. A slot  406  is provided along the sidewall of the shaft opening  404 . Preferably, the slot  406  extends the length of the shaft opening  404 . A bore (not shown) preferably extends through a first flange  408  into a stem  410  of the tilter shaft holder  402 , as with the bore  374  of the tilter shaft holder  342  (FIG. 8A). The tilter shaft holder  402  may include a second flange  412  opposite the first flange  408 . The locking mechanism  470  is preferably a set screw, and the bore is preferably at least partly threaded to receive the set screw. The threads of the set screw may be coated with nylon to securely engage the set screw with the bore. Alternatively, the locking mechanism  470  may be any other mechanism, e.g., a clasp, hasp, latch or clamp, which performs the equivalent function to constrict rotation about the axis C. The tilter shaft holder  402  preferably includes one or more recesses  414  and a hole  416  for receiving the tension mechanism  460 , as will be described below.  
         [0056]    The bushing  420  includes a slot  422  provided along its sidewall. Preferably, the slot  422  extends the length of the sidewall of the bushing  420  such that the bushing  420  has a non-closed annular shape. The bushing  420  is preferably a metal such as bronze. The bushing  420  is inserted into the shaft opening  404 . The slot  422  of the bushing  420  need not be aligned with the slot  406  of the tilter shaft holder- 402 . The tilter shaft  430  may then be inserted into shaft opening  404 .  
         [0057]    The arm mount  440  may be inserted into the channel  144  of the forearm extension  140  (FIG. 2). As seen in FIG. 10, the arm mount  440  may extend perpendicularly through the tilter shaft  430 . Preferably both the arm mount  440  and the tilter shaft  430  are a metal such as aluminum. The arm mount  440  may be welded to the tilter shaft  430 . When the arm mount  440  is securely attached to the forearm extension  140 , the adapter plate  302  may be adjusted, rotating about the axis C until the electronic device is appropriately positioned. Then the locking mechanism  470  is engaged by, e.g., inserting the set screw into the bore and tightening to close the slot  406  and the slot  422  to restrict rotation about the axis C. A lock washer  472  and/or a protective washer  474  may separate the head of the set screw from the tilter shaft holder  402 .  
         [0058]    The torsion spring  450  preferably includes a first tang  452  and a second tang  454 . The torsion spring  450  is so dimensioned as to be insertable into the tilter shaft  430 . The tilter shaft  430  preferably includes a hole  432  to receive the first tang  452  in order to secure one end of the torsion spring  450 . After the torsion spring  450  is inserted into the tilter shaft  430 , the tension mechanism  460  may be applied.  
         [0059]    The tension mechanism  460  preferably includes a body  462 , a recess  464 , one or more bosses  466  and a cap  468 . The body  462  is insertable into the interior of the torsion spring  450 , and the recess  464  receives the second tang  454 . Before fully inserting the tension mechanism  460 , the torsion spring  450  may be pre-tensioned to achieve a desired torque preload value by partly inserting the tension mechanism  460  and rotating it about the axis C. Preferably, the cap  468  is hex-shaped so that a user may employ a conventional hex wrench to pre-tension the torsion spring  450 . After pre-tensioning, the tension mechanism  460  may be fully inserted so that the bosses  466  securely engage the recesses  414 . Preferably, the recesses  414  and the bosses  466  are square-shaped. Upon full insertion of the tension mechanism  460 , the cap  468  securely maintains the torsion spring  450  within the shaft opening  404 . The tension mechanism  460  may be secured by, for example, a retaining screw  418  or other device inserted into the hole  416  of the tilter shaft holder  402  to engage the recess  464 .  
         [0060]    The torsion spring  450  provides a counterbalance or bias to ensure that a heavy and/or bulky electronic device does not cause the adapter plate  302  to rotate about the axis C even though the locking mechanism  470  is engaged. The torsion spring  450  may be selected depending upon the weight of the electronic device attached to the adapter plate  302 . The torsion spring  450  is preferably made from steel spring wire.  
         [0061]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.