FIELD OF THE INVENTION 
     The present invention relates to the field of adjustable furniture. In particular, the present invention is directed to a table having a mechanism to raise and lower the desktop portion of the table as desired by a user and which mechanism automatically locks into place after the desktop is raised or lowered and which optionally supports a computer processor and may be equipped with wheels for portability of said table. 
     BACKGROUND OF THE PRESENT INVENTION 
     Adjustable furniture, including adjustable height tables, have a long history of gradual innovation and improvement. For example, U.S. Pat. No. 6,055,912 issued to Doud et al. on May 2, 2000 discloses and claims an adjustable height ready-to-assemble table having a working area disposed between two upright support members and mounting brackets which can be manually adjusted to support the working area at different heights relative to a floor. The Doud et al. patent references other patents, including U.S. Pat. No. 327,413 issued to Rohrbach in September, 1885. 
     Other prior art includes U.S. Pat. No. 5,823,120 issued to Holmquist on Oct. 20, 1998 in which a stationary, vertically adjustable desk includes a desktop supported above a support stand. The Holmquist patent discloses and claims a first and a second gas spring means including a handle for manual operation of the gas spring means. Each of the gas spring means includes a valve for locking and unlocking movement of fluid or gas inside the gas spring means which is attached to the handle. 
     A continued need in the art exists for improved adjustable height tables, in particular, such tables that are portable and mobile, that support current technological needs of users (e.g., computer equipment) and that provide for different ranges of height adjustment (e.g., low-to-the-floor for children and greater spacing from the floor for adults). In addition, such improved adjustable tables should also accommodate all variety of chairs, including wheelchairs, for users of the table. Such a table should provide an easy to reach adjustment mechanism and should impart force to assist adjustment of the elevation of the table. The imparted force should be adjustable by the user so that very heavy objects placed on the table are adequately supported. Finally, such an improved table should be compact during shipment or delivery to the user, should be easy to assemble, and readily adjustable. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the continued need in the art described above. That is, the present invention teaches, describes, enables, illustrates and claims an improved adjustable height working area that is portable and mobile, that supports current technological needs of users (e.g., computer equipment) and that provides for different ranges of height adjustment (e.g., low-to-the-floor for children and greater spacing from the floor for adults). In addition, the present invention also may be configured to accommodate all variety of chairs, including wheelchairs, for users and/or operators of the improved desktop of the present invention. The present invention provides an easy to reach adjustment height mechanism that imparts force to assist adjustment of the height of the working area and the imparted force is adjustable by the user so that very heavy objects placed on the table are adequately supported during adjustment of the height of the table. Finally, the improved table of the present invention is compact during shipment and delivery to the user, and is very easy to assemble and operate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In this disclosure, only certain embodiments are depicted, and not all or every insubstantial change or modification of each such embodiment are depicted or described herein, although those of skill in the art to which the invention is directed will appreciate many insubstantial changes to the teaching of this disclosure that nevertheless fall within the spirit and scope of the invention. In this disclosure, reference numerals are used to refer to various elements, sub-elements and process steps and the same reference numeral is intended to denote all similar or identical elements set forth herein. 
     FIG. 1 is a perspective view of an embodiment of the improved desktop of the present invention depicting the working area at an upper range of vertical adjustment. 
     FIG. 2 is a perspective view of the embodiment depicted in FIG. 1, except as viewed from underneath the improved desktop of the present invention. 
     FIG. 3 is an elevational side view in partial cross section of the embodiments depicted in FIG.  1  and FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1 an embodiment of the improved, vertically adjustable desktop  10  of the present invention is shown having a working area  12  mounted to a first and a second vertical support  14 ,  16 . First and second vertical supports  14 ,  16  comprise first and second lower static supports  24 ,  26  and first and second upper static supports  34 ,  36 . Lower static supports  24 ,  26  are connected to upper static supports  34 ,  36  by an adjustable linkage  18  comprising a first arm  19  spaced apart from a second arm  21 . Linkage  18  is preferably pivotably connected at one end to one of lower static supports  24 ,  26  and at the other end to one of upper static supports  34 ,  36 . 
     As depicted in FIG. 2, the first and second vertical support  14 ,  16  are preferably mechanically coupled together with a first and second brace member  20 ,  22  to increase rigidity of the improved desktop  10  when fully constructed. The first brace member  20  preferably couples to a first and second static lower support portion  24 ,  26  of the vertical supports  14 ,  16 . The first and second static lower portions  24 ,  26  are preferably L-shaped with an elongate foot portion  17  extending outward to engage a floor surface to provide stability to the desktop  10 . Preferably, the elongate foot portion  17  extends beyond a front and rear portion of the working area  12  to add stability, although this is not a requirement for practicing the present invention. Optionally, and while not depicted in the drawings, the elongate foot portion  17  may have caster wheels, non-slip pads and the like coupled to the foot portion  17  to provide a measure of mobility and attachment, respectively to the desktop  10 . Alternatively, the foot portion  17  may be fastened to a floor surface with nails, adhesive, screws, hook and loop patches, and the like if desired for a given application and use of the desktop  10  of the present invention. While not depicted, additional support members coupled from the first to the second vertical support  14 ,  16  may be used to further increase the structural integrity of the assembled desktop  10  and one or more bracing members may be coupled from either vertical support  14 ,  16  to either the first or second brace member  20 ,  22 . In one embodiment, a storage compartment  50  (shown in FIG. 1) is coupled to the elongate foot portion  17  and configured for storage of an operational portion of a set of computer equipment. 
     Coupled at the upper end of each of the first and second vertical support  14 ,  16  are a pair of height adjustment actuators  30 ,  32  which preferably comprise paddle-shaped levers pivotably coupled to powered biasing forces, such as locking gas springs  25 , which are positioned inside upper static supports  34 ,  36  and are best seen in FIG.  3 . The opposite end of gas spring  25  is pivotably attached to first arm  19  of linkage  18 . Locking gas springs  25  serve to start the desktop  12  in motion when the user depresses actuators  30 ,  32 , thereby unlocking gas springs  25 . When either actuator  30  or  32  is released, gas springs  25  lock and stop desktop  12  at its current position. Desktop  12  is locked into this position until a user depresses actuators  30 ,  32  to reposition the desktop. 
     Height adjustment actuators  30 ,  32  are each manually engaged by depressing each actuator  30 ,  32  toward a protective lever guard member  38 ,  40  which also provides manual leverage during adjustment by an operator. Over the entire range of adjustable motion of the working area  12 , the height adjustment actuators  30 ,  32  are preferably disposed above said working area  12  at a constant height relative to the working area  12 . 
     In an embodiment utilizing a powered biasing force  25 , each actuator  30 ,  32  comprises a mechanical lever which is coupled to the powered biasing force  25  so that power is provided to the biasing force  25  on each of the vertical supports  14 ,  16  at the same time so that the working area  12  remains essentially in the same orientation (e.g., parallel or tilted) with respect to the surface on which the desktop  10  is positioned as the vertical height of working area  12  is adjusted. The powered biasing force may be provided by a gas spring, a stepper motor, a servo motor, or any type of linear actuator (including switches and a source of power if non-manual) including a leadscrew, a spring, a telescoping member, and the like. Furthermore, if a powered biasing force is used, preferably a limit, or stop, switch should be configured so that no damage occurs to the improved desktop due to an overextended amount of travel. 
     The working area  12  may be provided with a supporting frame member  42  to increase the rigidity and strength of the working area  12 . Such a support frame member  42  may take many forms such as one or more members spanning all or a portion of the underside of the working area  12 , an enclosed frame (as depicted in FIG.  1  and FIG.  2 ), of a combination of both types of frames. In addition, while not depicted, the frame may be disposed on the upper portion of the working area  12  in which case the frame member  42  may also provide a raised edge, or lip feature, around most of the periphery of the working area  12 . In a related embodiment, a functional equivalent of such a support frame member  42  may be incorporated into the working area  12 , such as positioned intermediate two outer layers forming the working area  12 , or disposed in an interior portion or cavity of said working area  12 . 
     In addition to a powered biasing force, such as locking gas springs  25  positioned in each upper static support  34  and  36 , additional units of biasing force may be provided to increase the lifting strength of desktop  10 . In the embodiment shown in FIG. 3, supplemental biasing force  23  is positioned on first arm  19  of linkage  18  and is attached to static lower portion  24 . In this embodiment, biasing force  23  is preferably a gas spring providing constant pressure and increasing the overall lifting strength of the desktop  10 . The lifting strength of the supplemental biasing force is preferably commensurate with the desktop load. 
     The working area  12  can be lowered until upper static supports  34 ,  36  reach and touch elongate foot portions  17 , and can be raised until the biasing force  25  has reached its full extension. In the depicted embodiment, the preferred range of vertical adjustment of the working area  12  relative to the floor supporting the desktop  10  is from about six to about thirty-one inches (6″ to 31″) so that the working area  12  may be fixed at any set height therebetween. One particular advantage of the desktop  10  of the present invention is the ability to adjust the height to less than about 20 inches above the surface on which the desktop  10  is positioned. 
     The lifting capacity of the desktop  10  is proportional to the weight loaded onto the working area  12 . If the weight loaded onto the working area  12  is less than about thirty pounds, almost no effort is required to raise or lower the working area  12 . If the weight loaded onto the working area  12  is about thirty to fifty pounds, only moderate manual assistance is required to raise or lower the working area  12 . If the weight loaded onto the working area  12  is greater than fifty pounds (but less than about eighty-five pounds, the structural maximum weight of the depicted embodiment), requires moderate manual effort to raise or lower the working area  12 . The use of supplemental biasing forces  23 , as shown in FIG. 3, can minimize or even substantially eliminate the manual effort required to adjust loads up to about 85 pounds. 
     The preferred materials for the desktop  10  include use of cold-rolled steel finished with a layer of corrosion resistant powder coating for the vertical supports  14 ,  16  and the first and second brace members  20 ,  22  as well as the tabletop frame  42 . The working area  12  is preferably fabricated from three-quarter inch (¾″) thick particleboard having a scratch and stain resistant laminate sheeting covering at least the upper portion of the working area  12 . Of course, a wide variety of materials may be used in lieu of the preferred particleboard, such as different thickness particle board, wood, metal or metal-alloy sheeting, ceramic material, resin or plastic material, composite material, tempered glass and the like. One advantage of using particleboard is that particleboard is relatively inexpensive and rigid and fastening components to particleboard is relatively simple and well known in the furniture industry. 
     The working area  12  may be of any desired shape, such as, but not limited to, rectangular, square, oval, round, kidney-shaped and the like. The working area  12  may also include any additional features found in desktops such as being split-leveled, fully or partially tiltable, and the like. 
     When the improved desktop  10  of the present invention is used for supporting a desktop style computer terminal or workstation, including the central processing unit (CPU) thereof, an optional CPU stand may be coupled to either vertical support member  14 ,  16  or other convenient structurally sound location so the CPU stand is spaced from the floor surface (and can be moved with and maintaining the mobility of the desktop  10 ). The CPU stand preferably is connected to the foot portion  17  with a cantilever-type mechanical fitting having vertical portions to retain a CPU for a computer terminal or workstation without reducing access to operable controls and input/output ports of said CPU. 
     The actuators  30 ,  32  may be formed of any relatively rigid material including metal, plastic or resin and the like. The actuators preferably comprise a mechanical linkage which provides a travel stop at each end of the range of adjustable motion for the working area  12  The actuators  30 ,  32  are preferably readily accessible to the user (or an assistant of the user) of the desktop  10  from the usual work location, or station, occupied by the user when working at and/or adjusting the elevation of the working area  12 . The actuators  30 ,  32  preferably must be simultaneously depressed in order to lift and lower the working area  12 . When either actuator  30 ,  32  is released the working area  12  will cease to move and locks into the then-present position. Likewise, the working area  12  cannot begin to lift or lower unless or until both actuators  30 ,  32  are depressed. The requirement of having both actuators  30 ,  32  depressed simultaneously adds to the safety of the operation of the improved desktop  10 . Although actuated biasing forces, such as gas springs  25 , have been shown and described herein, other mechanisms for lifting and lowering the desktop  10  are contemplated by the present invention. Such mechanisms include, but are not limited to, other fluid-containing springs, motors, screws and the like. Furthermore, the embodiments contained herein describe a manual actuation of the biasing forces in the upper static supports  34 ,  36 , but the actuation may be computer-controlled so that the desired position of working area  12  can be programmed and automatically adjusted based on, for example, different user heights, different work types, and the like. 
     The desktop  10  of the present invention advantageously utilizes identical vertical supports  14 ,  16  having pre-drilled and pre-configured mounting locations for the working area  21  and the first and second brace members  20 ,  22 . Preferably the vertical supports  14 ,  16  are essentially identical in configuration and are preferably assembled prior to packing and shipping the desktop  10  to a user. Thus, the packaging for the desktop  10  is compact and readily shipped at standard shipping rates by weight. 
     To assemble the desktop  10  of the present invention requires merely that the user couple the working area  12  and the first and second brace members  20 ,  22  to the first and second vertical support. Optionally, and as mentioned above, caster wheels and the like may be added to the foot members  17 , a CPU stand may be coupled to the foot member  17 , and additional biasing force  23  may be added (via a pair of supplemental gas springs). The lifting capacity of the pair of supplemental gas springs  23  is proportional to the desired weight resting on the desktop  10 . The lifting and lowering efforts can be largely counterbalanced up to a load of 85 lbs. to increase the mechanical advantage provided by the desktop  10 . The additional biasing force  23  may be added by the user (or ordered in advance and fitted by the manufacturer) to the desktop  10 . The resulting assembly is ready for immediate use. 
     The appended claims define the claimed invention, although those of skill in the art to which the present invention is directed will appreciate that the techniques, processes and equipment according to the present invention may be insubstantially modified without departing from the spirit and scope of the present invention as defined by the following claims. A primary thrust of the design of the present invention is to create an improved desktop which can be adjusted to lower heights.
An improved adjustable desktop that is portable and mobile, that supports current technological needs of users (e.g., computer equipment) and that provides for different ranges of height adjustment (e.g., low-to-the-floor for children and greater spacing from the floor for adults). The desktop includes a working area with an end portion, a vertically adjustable support member pivotably coupled to the end portion and a manual actuator coupled to the vertical support. The manual actuator is disposed above both the working area and the vertically adjustable portion of said vertical support member allowing for easy adjustment of the vertical height of the work surface.