Abstract:
An ergonomic console for a computer workstation having a horizontally extendible shelf which is vertically adjustable in increments of height to provide a comfortable clearance for different size persons. The shelf is slidable in tracks at either end, and adjuster plates on the interior sides of the console include vertical slots with rearwardly extending notches at spaced intervals which receive bushings extending from either end portion of the tracks.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to furniture, and more particularly to an adjustable work surface for supporting a computer keyboard, monitor, mouse, digitizer board, joy stick or like accessories in a computer workstation. 
     Computer workstations are designed to be attractive and to provide an ergonomic interface with the computer operator for maintaining optimum proficiency over prolonged intervals of time without fatigue or physical discomfort. The workstation typically includes a monitor positioned on a shelf within an open console for viewing above, at or below the operator&#39;s eye level, and a keyboard located in front of the monitor on a separate shelf. The heights of the shelves from the floor, may be made adjustable by interengaging the ends of the shelves with vertically aligned fittings spaced vertically from one another at intervals on the interior sides of the console. 
     The keyboard height is especially critical. During keying, the operator&#39;s wrists should remain in a neutral position--not bent up, down or sideways--to reduce discomfort from unnecessary wrist stress. Improper wrist position over a prolonged period may increase risk of repetitive strain injury, a common form of mononeuropathy referred to as carpal tunnel syndrome. Therefore, the anthropometric parameters of the operators are important design criteria for workstations in general, and for keyboard shelf height in particular. ANSI/HFS 100-1988 Standards for Independent Keyboard Surfaces, Independent Display Surfaces and Clearance Under Work Surfaces, for example, require a minimum surface height from the floor of 23 inches for the 5th percentile female (approximately 5&#39;0&#34; tall) and 28 inches for the 95th percentile male (approximately 6&#39;2&#34; tall). However, the keyboard shelf should be adjustable within a range of greater heights to accommodate shorter and taller operators, as well as or the unique personal preferences of operators between the 5th and 95th percentiles. 
     Another feature often desired in computer consoles is a horizontally slidable keyboard shelf which can be completely retracted into the console when it is not in use. However, such keyboard shelves cannot be easily adjusted vertically. This is because the tracks in which the ends of the shelf move are permanently attached to the interior sides of the console. To reposition the keyboard to another height from the floor, the shelf must be removed from the tracks in order to allow access to the means fastening the guides to the console. This is time-consuming and often impractical, especially when several operators, short and tall, share the same workstation. Instead, the operators might forego adjusting the height and unwittingly expose themselves to the insidious consequences of wrist strain. 
     Accordingly, it is an object of the present invention to provide, in a computer workstation, a work surface for a keyboard and like control accessories which can be ergonomically adjusted in height to alleviate discomfort from unnecessary wrist stress to the operator. 
     Another object is to provide, in a console, a horizontally extendible work surface which can be quickly and easily adjusted, within a range of heights, to suit the physical comfort and unique preferences of users. 
     Still another object is to provide a work surface which is horizontally slidable between supporting sides of a workstation, and the height of which can be easily adjusted. 
     A still further object is to provide a horizontally slidable work surface which can be changed from a horizontal position to a forwardly or rearwardly slanted position. 
     Still another object is to provide a work surface for a workstation which is simple to adjust in height and slant, which is completely retractable, and which can securely support a computer keyboard and other items employed by an operator. 
     Briefly, these and other objects and aspects of the invention are accomplished by a workstation having the following construction. A supporting surface is provided, having opposite edge, each edge having a track-engaging slide. A pair of tracks is provided, the tracks being located alongside the opposite edges of the supporting surface and slidably receiving the track-engaging slides to permit sliding of the supporting surface in a path defined by the tracks. Each of the tracks has front and rear projections for engaging a supporting slot. First and second plate means are provided. The first plate means is located alongside one of the opposite edges of the supporting surface, and the second plate means is located alongside the other of the opposite edges of the supporting surface. Each of the first and second plate means is supported at a predetermined height. The first plate means has a front supporting slot receiving the front projection of one of the tracks and a rear supporting slot receiving the rear projection of the same track. The second plate means has a front supporting slot receiving the front projection of the other track and a rear supporting slot receiving the rear projection of the same track. One of the slots in each plate means comprises a vertically elongated section having a plurality of notches extending therefrom, at vertically spaced locations, in a direction transverse to the direction of elongation of the slot, for receiving one of the projections. The other of the slots in each plate means also comprises a vertically elongated section having a plurality of notches extending therefrom, at vertically spaced locations. Each of the latter notches extends transverse to the direction of elongation of said other of the slots and has a downwardly extending pocket formed therein and spaced from the vertically elongated section, for receiving another one of the projections. With this structure, for vertical adjustment of the position of the supporting surface, the track-providing means must be moved upward, and then horizontally, to position the projections in the vertically elongated sections of the slots. 
     Further objects, advantages and details of the invention will become apparent from the following detailed description when read in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a computer workstation with an adjustable keyboard shelf according to the invention; 
     FIG. 2 is an exploded view of front and rear adjuster plates, a track, and one end of the shelf, spatially offset from the left side of the workstation of FIG. 1; 
     FIG. 3 is an isometric view of the track of FIG. 2 taken from the side normally facing the adjuster plates; 
     FIG. 4 is a view in cross section of the track taken on plane 4--4 of FIG. 3; and 
     FIGS. 5a-5d are schematic views in elevation of the track installed in the front and rear adjuster plates showing the track supported at various heights and slants. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a desk-like open console, generally indicated by the reference number 10, designed as a workstation for a computer terminal including a CPU, video monitor and a keyboard. Console 10 may be constructed of solid wood, laminate or particle board, molded solid plastics or other materials suitable for rigid construction. It includes left and right side panels 12a and 12b in fixed parallel relation by a horizontal top shelf 14, bottom shelf 15 and back panels 16. Shelves 14 and 15 provide fixed support surfaces for a CPU and other computer components and accessories (not shown) such as a printer or program libraries. A vertically adjustable video monitor shelf 18 is supported between the interior sides of panels 12a and 12b by a pair of dowel pins (not visible in the drawing) beneath the ends. The pins are removably inserted into selected ones of holes 22 which are arranged in the panels along two parallel vertical rows in several increments of elevation. 
     The keyboard (not shown) is supported on a shelf 20 in which the ends slide horizontally within reciprocal tracks 24a and 24b between a fully retracted position in console 10 and extended operating position. Without having to be removed from console 10, shelf 20 is also vertically adjustable by the positioning of the tracks in reciprocal front adjuster plates 26a and 26b and reciprocal rear adjuster plates 28a and 28b fixed to the interior sides of respective panels 12a and 12b. 
     Track 24b, and adjuster plates 26b and 28b are mirror images respectively of track 24a and adjuster plates 26a and 28a, which are described hereinbelow with reference to FIG. 2. Track 24a defines in cross section a U-shaped channel in which the adjacent end of shelf 20 slides. A rail 30 extending from the end of shelf 20 rides on an idler wheel 32 for reducing friction between shelf 20 and track 24. The bottom surface at the front end 30a of rail 30 is indented to bias shelf 20 toward the retracted position when idler 32 and the indentation register. 
     As best seen in FIGS. 3 and 4, track 24a further includes front and rear bushings 34 and 36, secured thereto by nut and bolt fasteners 37, and positioned to extend through apertures 38 and 39 of adjuster plates 26a and 28a and into recesses 40 and 42 formed in panel 12a, and located behind the plates. Aperture 38 comprises a narrow vertical slot 38a with rearwardly and downwardly curved notches 38b at vertically spaced increments, and an enlarged opening 38c at the lower end sufficient for passing bushing 34 when initially installing track 24a. A neck portion 34a of bushing 34 next to track 24a is reduced in size an amount sufficient for it to slide along slot 38a and seat in any one of notches 38b when bushing 34 is fully inserted through adjuster plate 26a. The curvature of notches 38b forms pockets which restrict bushing 34 from horizontal motion and thereby prevent track 24a from being repositioned without first lifting bushing 34 from the pocket. Aperture 39 similarly defines a narrow vertical slot 39a with notches 39b slanted rearwardly and downwardly at vertically spaced increments. An enlarged opening 39c at the lower end of slot 39a permits bushing 36 to be initially installed in plate 28a. Unlike the curved notches in plate 26a, the notches 39b are slightly slanted in order to permit bushing 36 to slide out freely without being first lifted. 
     Installation and use of the invention are extremely simple and require no special tool or mechanical aptitude. With adjuster plates 26a, 26b and 28a, 28b previously mounted in place over recesses 40 and 42 in panels 12a and 12b, bushings 34 and 36 of each track 24a and 24b are inserted through enlarged openings 38c and slid upward along vertical slots 38a and 39b and rearwardly into selected notches 38a and 39b of the same elevation. The ends of shelf 20 are then slid into tracks 24a and 24b. When fully inserted into console 10, shelf 20 is biased toward the retracted position by interengagement of idler 32 and the indentation at end 30a. The height of the work surface from the floor may be adjusted easily. The operator may withdraw shelf 20 straight out from the tracks, move the tracks to notches 38a and 39a at another level, and replace the shelf. It is also possible to adjust the height without removing the shelf by simply lifting the front end of the shelf 20 together with tracks 24a and 24b, and drawing them from the console until the bushings 34 and 36 can slide in the vertical slots 38a and 39b to different notches 38b and 39b. 
     FIGS. 5a-5d illustrate typical examples of seven levels of track settings for various shelf positions which meet or exceed the ANSI/HFS 100-1988 Standards range for adjustable work surface heights of 23 inches to 28 inches although any heights may be achieved by making the plates larger, with more slots, or placing them in different positions on the side panels. In FIG. 5a, the track 24a is in its lowest position at openings 38c and 39c to provide a horizontal work surface height h of 23 inches from the floor. In FIG. 5b, track 24a is in its highest position in the top notches 38b and 39b to provide a horizontal work surface at a height h of 28 inches. In FIGS. 5c and 5d the bushings of track 24a are in different notches of the front and back adjuster plates 26a and 28a to provide a forward or rearward incline to the work surface. The straight slant of notches 39b allows front bushing 34 to remain fully seated in curved notches 38b at different inclined positions. 
     Modification of the console and adjustable surface are possible within the scope of the invention. 
     For example, while, in the embodiment specifically described and shown, separate front and rear slotted plates are provided on each side of the console to receive the respective front and rear bushings of the tracks, it is possible to provide a single plate, having both front and rear slots, on each side of the console. This modification is particularly useful underneath table tops, where no vertical panels are available for the mounting of separate front and rear plates. 
     The invention may be used to provide an adjustable monitor support shelf or an adjustable shelf for supporting a printer or other article. 
     Some of the many advantages and novel features of the invention should now be readily apparent. For example, a work surface for a computer workstation is provided which is adjustable within a range of heights which ergonomically alleviates discomfort from unnecessary wrist stress to the operator and which can be designed to meet or exceed ANSI/HFS 100-1988 Standards. The work surface is horizontally extendible, can be adjusted in height to suit the physical comforts and any unique preferences of users, can be inclined inwardly or outwardly from a horizontal position, and is relatively simple to adjust, in both height and inclination, without any special skills or tools. 
     It will be understood that various other changes in the details, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principal and scope of the invention as expressed in the appended claims.