Automatic Vertically Adjustable Work Surface

The invention relates to a work station having an automatically vertically adjustable work surface to accommodate workers of different heights.

There are at least 10 million video display terminals (hereinafter referred to as VDTs) in use across the country and it is predicted that there will be at least 40 million VDTs by the end of this decade. While VDTs are used for a variety of tasks, they are used most intensively by a range of office workers who may spend the entire day key-punching and processing information. VDTs have been instrumental in increasing productivity and efficiency for virtually every major industry, and will continue to play a central role in this country's economy.

However, as the number of VDTs in the work place has risen so have the health complaints associated with their use. Surveys indicate that a majority of full-time VDT users report high frequencies of health problems Among other problems, recent studies confirm that VDT users have higher incidences of problems such as eye strain, headaches, insomnia, back and neck strain and fatigue.

As these health concerns have been recognized as legitimate and serious, steps are being taken in at least twenty states to introduce legislation to institute health and safety protections for VDT users. While questions have been raised regarding whether VDTs emit harmful radiation, studies show that the radiation levels emitted by the VDTs are well below levels naturally found in the environment. Thus, it is generally concluded that radiation is not the primary cause of the physical problems discussed above. In contrast, numerous studies have indicated that operator injury such as carpal tunnel syndrome and tenosynovitis, which are cumulative trauma injuries, are caused by improper VDT workstation design.

In particular, the conventional VDT workstation is designed such that the work surfaces cannot be adjusted to accommodate people of different height. Shorter people must arch their body and elevate their arms in order to properly operate the keyboard and view the display terminal. In contrast, taller people have to hunch over to access the keyboard and view the terminal. Accordingly, the conventional VDT work stations have resulted in a high frequency of health-related problems.

FIG. 1 illustrates the conventional video display terminal work station As shown in FIG. 1, the conventional work station includes a plurality of interconnected panels 1 having a plurality of elongate vertically extending support rails 2. Each of the support rails 2 includes a plurality of slots disposed along the vertical length thereof. Support brackets 3, having a plurality of teeth protruding therefrom, are secured to the support rails 2 by inserting the teeth of the support brackets into the complimentary corresponding slots of the support rails 2. The work surface 4 is supported by a pair of the supporting brackets 3.

Thus, while the conventional work surface is vertically adjustable, such vertical adjustment can only occur by disassembling the table top from the brackets and vertically adjusting the location of the support brackets on the support rails. Accordingly, to vertically adjust the conventional work surface it is necessary to remove all items therefrom, including the video display terminal. It is therefore not practical to adjust the height of the work surface on an hourly or daily basis to accommodate a change in shift of workers of different heights. Therefore, rapid, automatic, vertical adjustment of the work surface is not possible resulting in an unhealthy working environment.

Further, Carpal Tunnel Syndrome (CTS) is an ailment affecting the wrists, arms and hands, which many times results from prolonged use of computer keyboards. The syndrome is named after the Carpal Tunnel which is located in the wrist and forms the passageway for passing nerves and tendons from the arm to the hand. When the wrist is bent, the Carpal Tunnel narrows and compresses the tendons and nerves. If the wrist is bent for a long period of time, the resulting compression may damage the tendons and nerves, resulting in the onset of CTS.

Even when the keyboard operator is in an ideal typing posture the operator s hands are bent slightly outward. When the operator is in a less than ideal posture further wrist bending is required to operate the keyboard. As described above, wrist bending that takes place over an extended period of time, as is usual with these types of jobs, results in prolonged compression of the nerves and tendons increasing the likelihood of protracting CTS.

It is an object of this invention to provide a retrofitting device for retrofitting an existing work station such that the work surface can be rapidly and automatically vertically adjustable.

It is a further object to provide a retrofitting device for retrofitting an existing work station such that the work surface can be vertically adjusted while the video display terminal is disposed thereon.

A further object is to provide an inexpensive retrofitting device for retrofitting a standard work station with a vertically adjustable work surface without requiring a redesign of the existing work station.

Further, another object is to provide a vertically adjustable work surface, permanently attached within a workstation.

Another object is to insure that the operator correctly positions his hands vertically with respect to a keyboard placed on the work surface.

A still further object is to provide a vertically adjustable free-standing work surface.

These and other objects which will become apparent from the ensuing description of the preferred embodiment of the invention are accomplished according to the present invention by a vertically adjustable, retrofittable work station adapted to be mounted to an existing wall panel. The retrofittable work station comprises a pair of horizontally spaced, vertically oriented support rails secured to the panel a work surface, a first pair of elongate vertically oriented, rails horizontally displaced from one another and adapted to be individually and stationarily mounted to the support rails, a second pair of elongate, vertically oriented, rails individually slidably mounted to the first pair of rails, means for individually mounting the support brackets and thus the work surface to the second pair of rails, a pair of elongate, horizontally oriented, channel members for respectively interconnecting the first and second pairs of rails and a driving mechanism coupled between the first and second channel members for selectively displacing the channel members towards or away from each other to attendantly vertically displace the work surface. To allow for retrofit, the first pair of stationary rails have a plurality of teeth extending therefrom which are shaped and arranged in the same manner as the teeth which extend from the support bracket. In this manner, the stationary rails can be secured to the existing support rails. In addition the second pair of slidably mounted rails have a plurality of slots corresponding to the slots in the existing support rails such that the existing support bracket can be secured to the slidable rails to thereby provide an automatically vertically adjustable work surface.

The above-described retrofit can be permanently installed by replacing the existing support rails with the stationary rails of the vertically adjustable work surface. In this arrangement, the stationary rails are fixedly attached to the panel, thus eliminating the need for the support rails, and providing a permanently attached work surface.

In the vertically adjustable free-standing worksurface, the stationary rails themselves serve as free-standing support means in the form of vertical legs respectively mounted on horizontal feet which rest on the floor. Alternatively, an upright telescopic vertical support means may be employed.

FIG. 1 is a perspective view of the conventional VDT workstation;

FIG. 2 is a front view of the vertically adjustable, retrofittable workstation of the present invention;

FIG. 3 is a side view of the vertically adjustable workstation of the invention;

FIGS. 4, 5 and 6 are sectional views taken along the lines IV--IV, V--V AND VI--VI of FIG. 2, respectively;

FIGS. 7, 8 and 9 are sectional views taken along the lines of VII--VII, VIII--VIII, and IX--IX of FIG. 2, respectively; and

FIG. 10 is a sectional view taken along the line X--X of FIG. 2;

FIG. 11 is a front view of the vertically adjustable workstation of the invention, permanently mounted to a panel;

FIG. 12 is a sectional view taken along lines XII--XII of FIG. 11:

FIGS. 13 and 14 are front views of the vertically adjustable work surface with a linkage drive;

FIG. 15 is a perspective view of an L-shaped vertically adjustable work surface with a linkage/cable drive;

FIG. 16 is a front view of the vertically adjustable workstation illustrating a dual drive screw arrangement for raising or lowering the work surface;

FIG. 17 is a front view of the vertically adjustable workstation illustrating a pulley and cable method for raising and lowering the work surface;

FIGS. 18 and 19 are sectional views of FIG. 17;

FIG. 20 is a front view of the vertically adjustable workstation with a gear/linkage drive;

FIG. 21 is a perspective view of an L-shaped vertically adjustable workstation with a gear/linkage drive;

FIG. 22 is a perspective view of a vertically adjustable free-standing work surface utilizing an alternative gear linkage drive system;

FIG. 23 is a front view of a vertically adjustable free-standing work surface employing an upright telescopic vertical support means;

FIG. 24 is a side view of the free-standing work surface of FIG. 23; and

FIG. 25 is a cross-sectional view through one of the telescopic support means.

As discussed above and as shown in FIG. 1, the conventional work station includes a plurality of panels 1 serving as support means and interconnected by support rails 2 having slots disposed therein for receiving the correspondingly shaped teeth of the support bracket 3 for supporting the work surface 4 The retrofittable device of the invention is a vertically adjustable unit which is designed to be mounted on the existing support rails 2 and to support the existing support bracket 3 for supporting the work surface 4 in a vertically adjustable manner.

Particularly, as shown in FIGS. 2 and 3 the retrofittable device of the invention comprises a pair of stationary rails 5 adapted to be mounted on the existing support rails 2, a pair of slidable rails 6 individually slidably disposed on the stationary rails 5, a slidable channel 7 connecting each of the slidable rails 6 a fixed channel 8 connecting each of the stationary rails 5 a support bracket 3 for supporting the work surface 4 and a driving mechanism coupled to the slidable channel 7 and fixed channel 8 for selectively displacing the channels towards or away from each other to attendantly vertically displace the work surface 4. Alternatively, the work surface may be permanently mounted to the workstation panel, as shown in FIGS. 11 and 12. In this arrangement, the stationary rails 5 of the adjustable work surface replace the support rails 2 of the existing panel In particular, the stationary rails 5 are permanently mounted to the panel in place of the support rails 2, so that the vertically adjustable unit is permanently attached to the existing panel The securing plate 9, teeth 10, slots 11 of the existing vertical support rails 2, and the existing vertical support rails 2 are all thereby eliminated. Additionally, since the stationary rails are secured to and supported by the panel, the fixed channel 8 can also be eliminated.

Referring to FIG. 3, the stationary rails 5 are vertically extending elongate members for securing the retrofittable device to the support rails 2 of the existing panel In cross-section, the stationary rails 5 are substantially G-shaped as shown in FIGS. 5 and 6. Secured to each of the stationary rails 5 is an elongate securing plate g extending the length of the stationary rail 5. As shown in FIG. 3 the securing plate g has a plurality of engaging teeth 10 extending therefrom along the vertical length of the stationary rail 5. The teeth are shaped and arranged to correspond to the shape and arrangement of the teeth extending from the existing support bracket 3. Thus, the teeth 10 of the securing plates 9 are insertable into the slots 11 of the existing vertical support rails 2 in the same manner that the support brackets 3 are conventionally insertable into the slots 11 of the support rails so as to allow for the stationary rails 5, and hence the retrofittable device, to be easily mounted to the existing rails 2.

The slidable rails 6 are also G-shaped in cross-sections to correspond to the shape of the stationary rails 5, a pair of sliding bushings 12 are secured to each of the slidable rails 6 at upper and lower portions thereof. Each of the bushings 12 comprise a pair of L-shaped substantially frictionless members 13 14 which are interconnected such that one of the frictionless members 13 is disposed on the inside of the G-shaped slidable rail 6 while the other frictionless member 14 is disposed on the outside of the G-shaped slidable rail 6. The frictionless members 13 14 are connected by dowel pins 15, screws or the like to the slidable rails 6. Thus, the frictionless members are fixedly attached to the slidable rails 6 so as to slide therewith relative to the stationary rails 5 to allow for smooth vertical adjustment of the slidable rails 6. As shown in FIGS. 2 and 3 each of the slidable rails 6 has a plurality of slots 16 disposed along the length thereof. The slots 16 are shaped and arranged in the same manner as the slots 11 provided in the existing support rails 2. Accordingly, the existing support brackets 3 can be secured to the slidable rails 6 in the conventional manner by inserting the teeth 17 of the support brackets 3 into the complimentary slots 16 of the slidable rails 6.

The slidable channel 7 and fixed channel 8 respectively interconnect the slidable rails 6 and the stationary rails 5, as illustrated in FIG. 2. That is, the slidable rails 6 are interconnected by the slidable channel 7 and the stationary rails 5 are interconnected by the fixed channel 8. The channels 7, 8 are dimensioned in length such that the overall width of the retrofittable device corresponds to the standard distance between existing support rails 2 in conventional work stations For example, the distance between the support rails in standardized work stations is either 48 or 64 inches. Correspondingly, the channels are dimensioned such that the distance between the stationary rails is either 48 inches or 64 inches such that the retrofittable device can be used to retrofit any standard size work station. The slidable channel 7 and stationary channel 8 are respectively connected to the slidable rails 6 and the stationary rails 5 in the manner shown in FIGS. 2, 5 and 6. Specifically, each of the stationary rails 5 and slidable rails 6 include a pair of U-shaped connector links 18 extending perpendicularly therefrom. Referring to FIG. 4, the slidable rail 6 and stationary rail 5 are respectively secured to the slidable channel 7 and fixed channel 8 by respectively securing the pair of connector links 18 to the outer correspondingly U-shaped portions 19 of the W-shaped channels using screws or the like.

As shown in FIG. 4, and mentioned above the cross-sectional shape of each of the channels 7, 8 is in the form of a "W" which results in a high bending strength with a minimal weight. Of course, other cross-sectional shapes that result in high bending strength and minimal weight could be used instead.

As shown in FIGS. 1 and 3, the support brackets 3 are substantially L-shaped members having a plurality of teeth 17 protruding therefrom. The teeth 17 are engageable with the slots 16 of the slidable rails 6 such that the support brackets 3 extend perpendicularly from the slidable rails 6 away from the existing panel 1 to support the work surface 4 thereon.

Having fully described the overall structure of the retrofittable device the driving and guide mechanism for selectively displacing the channels toward or away from each other to attendantly displace the work surface will be described hereinafter.

Referring to FIGS. 2 and 7-10, the driving/guide mechanism generally includes a slide plate 20 a drive screw 21 and a motor 22 secured to the slidable channel 7 as well as a drive nut 23 and a bearing bracket 24 fixedly attached to the fixed channel 8. The slide plate 20 is a substantially U-shaped plate which is fixedly secured to the slidable channel 7 at the top end of the slide plate 20 and which extends vertically downwardly therefrom. The slide plate 20 includes two flanges 25 on opposing sides thereof to which linear bearings 28 are individually attached. In particular, the linear bearings 28 are substantially rectangular in cross-section and include a slot extending longitudinally thereto in which the flanges are respectively secured. The linear bearings 28 are individually secured to the flanges 25 using a plurality of dowel pin 29 inserted into aligned holes in the linear bearing and the flange, as shown in FIG. 9. Of course, the linear bearing could be secured to the flange by any suitable manner. The linear bearings 28 are in sliding engagement with the bearing bracket in the manner described hereinafter.

The motor 22 is fixedly secured to the slidable channel 7 and includes the rotatable drive screw 21 extending vertically downwardly therefrom. The drive screw 21 is threadedly engaged with the drive nut 23 which is fixedly secured to the stationary channel 8 in the following manner.

A substantially U-shaped vertically extending cover 26 is secured to the stationary channel as shown in FIGS. 2. 9 and 10. The cover 26 extends downwardly a sufficient distance to cover the drive mechanism. Secured to the interior portion of the cover is a U-shaped inner bracket 27 for securing the drive nut 23 and the bearing bracket 24. Specifically, the drive nut 23 is secured to the interior portion of the inner bracket 27 using screws or the like. The drive nut 23 is oriented such that the axis of the threaded hole extends in vertical direction to receive the drive screw 21. One type of drive nut 23 is a Delcron drive nut having a low friction coefficient. In the case where the stationary rails 5 are mounted directly in the panel and the fixed channel is eliminated, the nut can be secured to the panel.

The bearing bracket 24 is secured to the inner bracket 27 as shown in FIG. 8. The bearing bracket 27 is substantially C-shaped and extends in the vertical direction The outer portions of the bearing bracket are dimensioned to slidably receive the linear bearings 28 individually secured to the flanges 25 of the slide plate 20 in the manner described hereinabove. In this manner, the slide plate 20, in sliding contact with the bearing bracket 24 distributes the torsional force resulting from the torque of the drive screw to prevent any distortion of the device.

Accordingly, upon rotation of the drive screw, the slidable channel, and attendantly the slidable rails and the work surface, moves in the vertical direction to thereby adjust the elevation of the work surface.

Although the above embodiment describes the drive motor 22 secured to the slidable channel 7, an alternative arrangement, would be to eliminate the slidable channel 7, secure the drive motor to the underside of the work surface, and permanently secure the work surface to the slidable rails.

A further alternative is described as follows and illustrated in FIGS. 13 and 14. FIG. 13 illustrating the work surface in the lowermost position and FIG. 14 illustrating the work surface in the uppermost position. As shown in FIGS. 13 and 14, a linkage system is provided for causing the slidable channel to slide in the vertical direction and attendantly adjust the height of the work surface. Link 40 is stationarily secured to the fixed channel 8 and extends downwardly therefrom. The motor 55 is pivotably secured to an end of link 40 via rod 50 extending from the motor. The drive screw 56 extends in the opposite direction as the rod 50 and has a drive nut 57 threaded thereon. The drive nut 57 is secured to one end of first link 41 which is rotatably secured to the fixed channel 8 via pin 52 which extends through the fixed channel 8. Second link 46 is fixedly secured at one end thereof to pin 52 and extends substantially perpendicularly from the first link 41. Third link 47 is pivotably connected at one end thereof to the other end of second link 46 while the other end of third link 47 is pivotably connected to the slidable channel 7.

A fourth horizontal link 51 is connected at one end thereof to the other end of the first link 41 as shown in FIGS. 12 and 13. The other end of fourth link 51 is pivotably secured to an end of fifth link 50 which is pivotably secured at the other end to the fixed channel 8 via pin 53. Extending perpendicularly to the fifth link 50 is sixth link 48 which is fixedly secured to at one end to pin 53. The other end of sixth link 48 is pivotably secured to one end of seventh link 49, the other end of seventh link 49 being pivotably secured to the slidable channel 7. When the drive screw is rotated in a first direction so as to move the nut in the direction indicated by arrow A, the first link 41 is rotated counterclockwise as indicated by arrow B causing second link 46 to correspondingly rotate counterclockwise imparting an upward force on third link 47 to thereby move the slidable rail 7 upwardly. Additionally, when the first link 41 rotates counterclockwise, the fourth link 51 is translated in the direction of arrow C so as to cause the fifth link 50 and attendantly sixth link 48 to rotate counterclockwise, as shown by arrows D and E. respectively, to thereby impart an upward force on the seventh link 49 to assist in moving the slidable channel 7 upwardly.

If the width of the device necessitates an additional linkage can be provided as shown in FIGS. 13 and 14. Specifically, as shown therein, an eighth link 42 is secured at one end thereof to an end of the first link 41 while the other end of eighth link 42 is pivotably secured to one end of ninth link 43. Ninth link 43 is pivotably secured to the fixed channel 8 via pin 54. Tenth link 44 is fixedly secured at one end thereof to the pin 54 so as to extend substantially perpendicularly from the ninth link 43. The other end of tenth link 44 is pivotably secured to an end of eleventh link 45 which is connected at the other end thereof to the slidable channel 7. Accordingly, when the first link 41 rotates counterclockwise, the eighth link 42 is translated in the direction of the arrow F causing the ninth link 43 and the tenth link 44 to rotate counterclockwise as indicated by arrow G thereby imparting an upward force on the eleventh link 45 causing the slidable channel to move upwardly. In this manner, an upward force is imparted on the slidable channel uniformly along the length thereof such that the slidable channel will not experience binding even when an uneven load is provided on the work surface.

FIG. 15 illustrates an L-shaped work surface which is driven with a linkage system similar to that discussed above in regard to FIGS. 13 and 14. In particular, as shown therein, a roller bracket 76 rotatably supports rollers 77 in a vertically disposed manner at the corner of the L-shaped structure. A cable 71 connects the bottom portion of first link 41 to the bottom portion of twelfth link 73 via roller 77 while cable 72 connects the top portion of first link 41 to the top portion of twelfth link 73 via roller 77. The twelfth link 73 is pivotably secured at one end thereof to the fixed channel 8 via pin 76. Thirteenth link 74 is fixedly secured to the pin 76 such that it is rotatable with twelfth link 73. Finally fourteenth link 75 is pivotably connected at one end thereof to the other end of thirteenth link 74 and to the slidable channel 7 at the other end thereof. Thus, when first link 41 is pivoted in a given direction, as described above, the cables 71, 72 cause the twelfth link 73 to rotate in the same direction causing the slidable channel 7 to move upwardly or downwardly via links 74, 75.

FIG. 16 illustrates an alternative driving/guide arrangement according to another embodiment of the invention. As shown in FIG. 16, the driving/guide mechanism includes a dual drive screw arrangement where drive screws 60 are respectively rotatably secured to opposing ends of the slidable channel 7 and are respectively threadedly engaged with drive nuts attached to opposing ends of the fixed channel 8.

More particularly, a motor 22 is fixedly secured to the slidable channel 7, and a connector rod 58 is rotatably attached to the motor such that the connector rod 58 extends parallel to the slidable channel 7 and to opposite ends thereof. A 90 degree bearing gear 59 is disposed on each end of the connector rod, proximate to opposing ends of the slidable channel 7. A drive screw 60 is rotatably, vertically disposed on each slidable rail 6 such that one end of each screw is attached to the bearing gear 58 and rotatably driven by rotation of the connector rod 58 via the bearing gear 59. One of the drive screws has a forward thread while the other drive screw has a reverse thread. Each of the drive screws is threadedly engaged with a drive nut 61 which is secured to each of the stationary rails 5. Alternatively, the drive nuts 61 can be secured to opposing ends of the fixed channel 8.

Accordingly, upon rotation of the connector rod 58 each of the drive screws 60 are caused to rotate via the respective bearing gears 59 in opposite directions. However since the drive screws are threaded in an opposite manner with respect to one another, rotation of the drive screws causes the slidable channel 7, and attendantly the work surface 4, to be raised and lowered depending on the direction in which the motor is rotated.

An alternative driving and guide mechanism for selectively moving the work surface upward and downward is shown in FIGS. 17-19. The drive mechanism consists of a motor 22, a take-up reel 62, a cable 63 wrapped around the reel 62 and pulleys 64, 65, and 66. The reel 62 is attached to the drive shaft of the motor 22 which is secured to the fixed channel 8. In particular, the motor 22 is secured to outside of the fixed channel 8 with the drive shaft extending therethrough and the reel 62 is fixedly secured to the drive shaft on the inside of the fixed channel 8, the inside being the side closest to the panel 1.

The cable 63 extends from the take-up reel 62 in the manner described below. Since both sides of the cable drive mechanism are identical the description will be limited to the left side as illustrated in FIG. 16. The cable 63 extends from the take-up reel 62, horizontally and parallel to the fixed channel 8, around first pulley 64 attached to the inside of the fixed channel 8 at the left side thereof The cable then extends vertically upwardly, parallel to the stationary rail 5 and slidable reel 6 and around second pulley 65 attached to the top of the stationary rail 5. From second pulley 65 the cable extends horizontally, parallel to the work surface, around the third pulley 66 fixedly attached to the opposite stationary rail 5. Finally, the cable extends downwardly parallel to the stationary rail 5 and slidable rail 6 and is attached to the slidable channel 7 at one end thereof. The other end of the cable extends in the opposite manner so as to be connected to the other end of the slidable channel 7. In this manner, when the take-up reel 62 rotates in a direction causing the cable 63 to wind therearound, the cable 63 pulls the slidable channel 7 and attendantly the work surface 4 upwardly. When the take-up 62 reel rotates in the opposite direction so as to unwind each end of the cable gravity pulls the work surface downwardly.

An additional drive arrangement is illustrated in FIGS. 20 and 21. In particular. FIGS. 20 and 21 illustrate a gear/linkage drive system for raising and lowering the work surface. Referring to FIG. 20 a pair of first and second gears 80, 81 respectively having first and second arms 90, 91 extending therefrom are rotatably disposed on fixed channel 8 such that their respective teeth are engaged with one another. A link 82 is pivotably secured at one end thereof to the drive nut 57 and at the other end thereof to the slidable channel 8 via pin 92. The first gear 80 is fixably secured to the pin 92 such that pivotable movement of link 82 causes the first gear 80 to rotate correspondingly. Further, since the teeth of first gear 80 are engaged with the teeth of second gear 81, the second gear 81 rotates in correspondence with the rotation of first gear 80. A link 83 is pivotably secured at one end thereof to the end of first arm 90 and at the other end thereof to the slidable channel 7. Correspondingly, link 84 is pivotably secured at one end thereof to the end of second arm 91 and at the other end thereof to the slidable channel 7. Thus, when the drive screw 56 is rotated by motor 55 causing the drive nut to translate therealong in the direction indicated by the arrow, the link 82 rotates counter clockwise causing first gear 81 to rotate counter clockwise and second gear 80 to rotate clockwise, as illustrated by the arrows in FIG. 20. In this manner, the slidable channel 7 is moved downwardly by means of links 83, 84 respectively connected to arms 90, 91.

When the width of the work surface requires, an additional linkage system is provided for supporting the additional width of the work surface. In particular, as illustrated in FIG. 20 a link 85 is pivotably connected to the bottom portion of link 82 at one end thereof and to a link 86 at the other end thereof. The link 82 is pivotably secured to the fixable channel 8 by means of pin 88. Correspondingly, link 87 is fixably secured at one end thereof to pin 88 and pivotably secured at the other end thereof to link 89 which is pivotably secured to the slidable channel 7. Thus, when the drive nut is translated in the direction of the arrow, link 85 is moved in the direction indicated by the arrow causing links 86 and 87 to rotate counter clockwise as illustrated by the arrow in FIG. 20. In this manner, link 89 causes the slidable channel to be moved downwardly.

FIG. 21 is a perspective view illustrating the drive mechanism for raising and lowering an L-shaped work surface. The linkage arrangement is the same as the linkage arrangement discussed above in regard to FIG. 20. In particular, the gear/linkage arrangement is provided for both sides of the L-shaped work surface, as illustrated in FIG. 21. The right side includes first and second gears 80, 81 respectively having first and second arms 90, 91 extending therefrom which are respectively connected to links 83, 84. The left side has a similar arrangement including third and fourth gears 98, 99 respectively having third and fourth arms 102, 103 extending therefrom The third and fourth arms 102, 103 are pivotably connected to the slidable channel 7 to allow for vertical movement.

The first gear 80 and third gear 98 have pulleys 94 fixedly attached thereto so as to be rotatable therewith. Pulleys 97 are supported by bracket 96 at the corner of the L-shape configuration. An endless bolt 95 is provided around pulleys 94 and 97 so as to rotatably connect first gear 80 with third gear 98 as shown in FIG. 21. Therefore, when first gear 80 is rotated in the manner discussed above the pulley/belt system causes the third gear 98 to rotate via pulley 94. Due to the meshing engagement of the teeth of third and fourth gears 98, 99, rotation of third gear 98 causes fourth gear 99 to rotate as well attendantly causing the slidable channel to move vertically.

The retrofit procedure will be described hereinafter. Referring to FIG. 1, the desk top 4 and the existing support brackets 3 are removed from the existing vertical support rails 2. Thereafter, as illustrated in FIG. 3, the retrofittable device is attached to the existing rail 2 by securing the engagement teeth 10 of each of the stationary rails 5 into the slots of the existing support rails 2.

While the desk top can be automatically adjusted by a distance of twenty inches using the automatic drive mechanism, the retrofittable device can be secured at any elevation along the existing rails. For instance, the standard table top height is 301/4". Thus, it may be desirable to attach the retrofittable device to the existing rails such that the table top can be adjusted in both the up and down direction with respect to the standard 301/4" table top height. The table top can be automatically adjusted from a 25" minimum to 43".

Having secured the retrofittable device to the existing panel 1, the existing support brackets 3 are attached to the slidable rails 6 of the retrofittable device in the same manner that the support brackets 3 and normally attached to the existing rails 2. That is the engagement teeth 17 of the existing support brackets 3 are inserted into the slots 16 of the slidable rails 6 so as to be securely attached thereto. It should be noted that the support brackets 3 can be attached at various elevations along the slidable rails 6 providing an additional adjusting feature. Once the support brackets are attached to the sliding brackets, the table top 4 is placed on top of the support brackets 3 in the usual manner.

A free-standing sit down/stand up work surface utilizing a still further drive arrangement is illustrated in FIG. 22. In particular, FIG. 22 illustrates an alternative gear/linkage drive system for raising and lowering the free-standing work surface 4.

In this embodiment, the stationary rails 5 may themselves serve as free-standing support means in the form of vertical legs respectively mounted on horizontal feet 217, 217 which rest on the floor. In the alternative, the stationary rails 5 may be mounted on separate free-standing support legs which in turn are connected to the feet 217 217. As in the previous embodiments, the work surface 4 is mounted on support brackets 3. The brackets 3 are in turn connected to respective slidable rails 6 which are individually slidably disposed in the stationary rails 5. A slidable channel 7 is connected to each slidable rail 6. A fixed channel 8 is connected to each stationary rail 5. A additional upper fixed channel 8' is included for stability.

A motor 155 turns a shaft 156 clockwise (as viewed from the end). The shaft has a righthand thread 158 (e.g. 6 turns to the inch) and receives a drive nut 157.

A pair of first and second sector gears 180 and 181 are rotatably disposed via a back plate 200 on the fixed channel 8 such that their respective teeth are engaged with one another. The gears are rotatably mounted on studs 209 protruding from back plate 200. The gears 180, 181 are partially covered in front by a cover plate 201. Both the cover plate 201 and the back plate 200 include frictionless inserts (not shown) to firmly hold the gears. The first gear 180 is provided with an arm 190 extending therefrom. The second gear 181 is provided with a first arm 191 extending therefrom and a second arm 192 extending downward generally perpendicular to said first arm 191.

A link 183 is pivotably secured at one end thereof to the end of arm 190 of the first gear 180 and at the other end thereof to the slidable channel 7. Correspondingly, a link 184 is pivotably secured at one end thereof to the end of the arm 191 and at the other end thereof to the slidable channel. The arm 192 of the second gear 181 is pivotably mounted to the nut 157.

An arm 202 is welded to a lower portion of back plate 200 at the lefthand side thereof and extends vertically downward. A C-shaped bracket (not shown) is fixed to the arm 202. The bracket rotatably supports a protruding portion of the motor shaft which protrudes from a transmission housing 208 of the motor in a direction opposite to the threaded portion 158. In this manner, the motor assembly is pivotally supported by the arm 202.

Thus, when the shaft 156 is rotated by the motor 155 causing the drive nut 157 to translate therealong as indicated by the arrow A. the second arm 192 of the second gear 181 rotates counterclockwise so as to rotate the second gear 181 counterclockwise and the first gear 180 clockwise. In this manner, the slidable channel 7 and the work surface are moved upwardly by means of links 183 and 184 respectively connected to arms 190 and 191.

FIGS. 23-25 illustrate a free-standing work surface utilizing the same gear/linkage drive system as that of FIG. 22 but employing upright telescopic vertical support means.

In particular, the telescopic vertical support means includes outer vertical tubular members 220, 220 for the right side and left side. The outer tubular members 220, 220 are fixed by any suitable means, such as welding, to respective horizontal feet 217, 217. The feet 217. 217 may each include a pair of spaced apart glides 225. As seen in FIG. 24, the outer tubular members 220. 220 are disposed on the feet 217, 217 off center in the lengthwise direction of the feet.

Intermediate tubular members 221, 221 are telescopically and slidably disposed in each of the stationary outer members 220, 220. Further, inner tubular members 222, 222 are telescopically and slidably disposed in each of the intermediate tubular members 221, 221.

As seen in FIG. 25, corner members 224 formed of frictionless material are disposed within the outer members 220, 220 for slidably supporting the respective intermediate members 221, 221 and are likewise disposed within the intermediate members 221, 221 for slidably mounting the inner tubular members 222, 222. Each of the outer members 220, 220 includes a pair of slide stops 218a in the form of protruding stop brackets for stopping the upward travel of each of the intermediate members 221, 221. Likewise each of the intermediate members 221, 221 includes a pair of slide stops 219a for stopping the upward travel of each of the inner members 222, 222. The slide stops 218a and 219a are fixed to the outer member and intermediate member, respectively, and extend inwardly so as to engage with corresponding slide stops 218b and 219b fixed to the intermediate member and the inner member respectively when the members are fully extended.

The two inner members 222, 222 include flanges 223, 223 which are suitably fastened, such as by means of bolts, to the slidable channel 7. The slidable channel, 7 includes work surface support brackets 213, 213.

As seen in FIG. 23, the stationary channel 8 is fixed, such as by welding, to the two outer tubular members 220. 220. The gear/linkage drive system, including the motor 155, is identical to that of FIG. 22 and thus a detailed description is dispensed with. Note, like elements are denoted with like reference numerals.

As shown in FIG. 24, three-section telescopic covers or screens 230 may be mounted on the front and back of the free-standing adjustable work surface in order to cover the gear/linkage drive system and telescoping support means so as to be pleasing to the eye. The covers 230 are swingably mounted on, for example, hooks 228 disposed on the slidable channel 7 and lock into the feet 217. 217 at 229.

A low voltage rocker control on/off switch 227 is mounted at the front of the work surface 4 and is connected to motor 155 by an on/off low voltage wire 226.

Of course, the number of telescopic vertical support members is not limited to three and, for example, four telescopic members could be employed.

Additional features of the invention are described below.

A top cover 30 is provided above the work surface, as shown in FIG. 3. Specifically, the top cover 30 is connected at opposing lateral sides to the top of each slidable rail 6 and extends downwardly just below the work surface 4. Disposed on the top cover is the elevation adjustment switch 31 for selectively operating the motor to vertically displace the work surface to the desired elevation. Also disposed on the upper cover are the necessary VDT hook-up connections 32 as well as an electrical outlet 33. In addition, a lower skirt is disposed below the work surface to cover the portion of the drive mechanism which is not covered by the cover 26.

A wire guide device 67 is provided to assure that the wires supplying the electrical outlet 33, the VDT connection 32 and the motor do not become entangled in the drive mechanism and become damaged. The metal guide 67 is substantially clam shaped and includes two first and second arms 68, 69 and hinge 70, as illustrated in FIG. 16. The first and second arms 68. 69 are respectively connected at one end thereof to the slidable channel 7 and the fixed channel 8. The other ends of the first and second arms 68, 69 are pivotably secured to one another to form hinge 70. Thus, first and second arms 68. 69 are separated from one another as the slidable channel 7 moves away from the fixed channel 8, and approach one another when the slidable channel 7 moves toward the stationary channel 8. The supply wires 71 are secured to the wire guide in the manner illustrated in FIG. 16. Therefore as the slidable channel 7 moves up and down the wires are prevented from experiencing excessive bending over the range of the work surface's travel so that the wires do not become damaged.

In the alternative, as shown in FIG. 22 the wires 215 may be attached to channel 8 and cover 201 by clips 216. The wires 215 then continue along the arm 190 and link 183 up to the VDT. In this manner, the wires 215 are prevented from being damaged by the gear/linkage system.

Although the present invention describes the preferred embodiment of the invention, it should be understood that numerous modifications and adaptations may be resorted to without departing from the spirit of the invention. For instance, an emergency cut-off switch may be provided to prevent accidental vertical movement of the work surface.

Thus, the work station according to the invention provides, a solution to the problems associated with the conventional work stations discussed hereinabove. While the conventional work stations included substantially fixed, non-adjustable work surfaces resulting in stress related health problems for the VDT users the invention provides a work station having an automatically adjustable work surface to accommodate users of various heights to thereby provide a comfortable, substantially stress free working environment.