PROVISIONAL SPECIFICATION Application No. PQ0730 Application Date: 31 May 1999 APPLICANT: RUSSELL, Edwin Robin ADDRESS: 5A Hibemia Rise, Sorrento, WA 6020 ACTUAL INVENTOR: RUSSELL, Edwin Robin ADDRESS FOR SERVICE: Paul A Grant and Associates PO Box 60 Fisher, ACT 2611 INVENTION TITLE: WORKING SURFACE ADJUSTMENT The invention is described in the following statement:-

TECHNICALFIELD This invention relates to mechanisms for use in adjustably supporting a working surface. Though not limited thereto, the invention is particularly suited to the support of keyboards, drawing and painting boards, cutting and lay-up boards, platforms for supporting work to be assembled or repaired, and the like.

Because the working surfaces are most usually horizontal or nearly so, such a disposition will be assumed in this specification for the sake of simplicity. It will be appreciated, however, that the working surface or platform may be arranged vertical (or at any other angle to the horizontal), as in an adjustable back-rest.

The terms,'up'and'down','back'and'front'are thus relative rather than absolute and are employed as a matter of convenience.

BACKGROUND TO THE INVENTION The need for adjustable keyboard supports is well recognised and many mechanisms are known in the art that allow a keyboard support platform to be adjusted vertically and horizontally to suit the physique and working habits of a keyboard operator. More recently, it has come to be recognised that it is desirable for a keyboard to be tilted down and rearwards by up to about 15°, the exact angle being a matter for personal preference. A rearward tilt of a keyboard is often called a negative angle since, for some years, it was assumed that a forward tilt-or positive angle-was desirable. Because of the recognised benefit of a negative keyboard angle, some keyboards either have a built-in negative angle or are fitted with foldable feet-like supports that can be used to set the board at a preset negative angle. Accordingly, keyboard support platforms need to have a variable tilt angle to allow both for the personal taste of the user and the range of keyboards on the market. Moreover, some users find that changing the keyboard angle from time to time during the course of a working day assists in relieving muscle strain.

A number of mechanisms are known in the art that allow the angle of tilt of a keyboard support platform to be adjusted in the fore-and-aft direction. Most require

the use of two hands and some trouble to effect an adjustment. For example, it is known to pivot the keyboard support platform about a horizontal axis and to form slotted brackets on each side to take clamping screws. To adjust such boards, both screws need to be loosened, the platform moved to the desired angle with one hand while the other tightens one of the clamp screws. The other screw is then tightened. Such an adjustment is clearly most suited to the'set and leave' situation. It is poorly suited to the situation where a worker needs to adjust a keyboard during the course of a day or when a variety of people use the one board and each wishes to adjust the board to his or her preference. Moreover, the slotted side brackets normally project downwardly into the knee-space and can cause injury to the knees of the user or damage to his or her clothing.

OBJECTIVES OF THE INVENTION It is the general object of the present invention to provide means for adjusting the tilt of a platform or surface that is suited for use with a keyboard support platform OUTLINE OF INVENTION From one aspect the present invention comprises a mechanism for adjusting the tilt of a work surface or platform with respect to a frame or fixture, the platforrh being pivotally supported cantilever-fashion from the frame or fixture so as to project forwardly therefrom, and the mechanism including a transversely slidable and manually operable cam follower located by the frame/fixture or located by the platform, the cam follower being adapted to engage a transversely extending and sloping cam surface that is located by the platform or the frame/fixture, respectively, so that transverse movement of the cam follower causes a pivotal tilting movement of the platform with respect to the frame or fixture. The cam follower may be conveniently located slightly above and to the rear of the platform, or it may be arranged below and near the front of the platform. Preferably, the cam follower may be guided for transverse movement by a guide bar or slot.

The use of such a transversely sloping cam surface and cam follower can avoid the need for clamps or other nobs and provides an immediate visual indication of

the angular position of the platform. It allows the tilt of the platform to be adjusted and re-adjusted at any time or frequency without delay or inconvenience and can be readily implemented without any intrusion in the space below the platform or frame. Furthermore, the tilting mechanism requires little if any enlargement of the normal fixed (non-adjustable) frame and platform arrangement.

In one form, the cam means can comprise a transversely sloping surface formed on the front portion of the frame or on the rear portion of the platform against which portion of the cam follower can ride to effect the tilt of the platform, the sloping surface being located some distance in front of or behind the transverse axis about which the platform is pivotally mounted to the frame so that the platform is effectively supported by the pivotal mounting and the cam follower at the point where it bears upon the sloping surface. In so doing, however, the arrangement can be such that the cam follower is placed under a compression or tension.

Mechanisms of this type are well suited for use with the type of parallel arm linkages disclosed in my US patent 5,292,097 that can be employed for the vertical adjustment of a keyboard support platform without the need for nobs, levers or other clamping devices. However, the tilting mechanism of the present invention is also applicable to many other basic mechanisms for raising and lowering working surfaces, for moving them toward and away from the user and/or for turning or swivelling them. When so used, the basic mechanism becomes the frame that supports the tiltable platform. Alternatively, the tilting mechanism of the present invention may be attached directly to a fixture such as a desk, table, wall- bracket or the like.

DESCRIPTION OF EXAMPLES Having broadly portrayed the nature of the present invention, various examples will now be described by way of illustration only. In the following description, reference will be made to the accompanying drawings in which:

Description of the Drawings Figure 1 is a perspective view of a keyboard support platform having a tilting mechanism that comprises the first example.

Figure 2A is an enlarged partial end elevation of the support of Figure 1.

Figure 2B is a section end elevation of the support of Figure 1, the section being taken on plane II-II of Figure 3.

Figure 3 is a section front elevation of the support of Figure 1, the section being taken on plane Ht-Ht of Figure 2A.

Figure 4 is a sectional side elevation of an alternative tilting mechanism to that of Figures 1-3.

Figure 5 is a diagrammatic illustration, in front elevation, of a third type of mechanism suitable for use in the type of support of Figure 1.

Figure 6 is a diagrammatic illustration, in front elevation, of a fourth type of mechanism suitable for use in the type of support of Figure 1.

Figures 7 and 7A are diagrammatic illustrations of a fifth type of mechanism suitable for use in the type of support of Figure 1, Figure 7 being a front elevation and Figure 7B being a partial end elevation of Figure 7A.

Figures 8 and 8A are diagrammatic illustrations of a sixth type of mechanism suitable for use in the type of support of Figure 1, Figure 8 being a front elevation and Figure 7B being a partial end elevation of Figure 8A.

Figures 9 and 9A are diagrammatic illustrations of a fifth type of mechanism suitable for use in the type of support of Figure 1, Figure 9 being a front elevation and Figure 9B being a partial end elevation of Figure 9A.

Referring to Figures 1-3, the first example concerns a keyboard support mechanism 10 shown in Figure 1 including a tiltable keyboard support platform 12 that is pivotally attached by rivets 14 to a frame or bracket 16 that is pivotally mounted on the ends of a parallel arm mechanism 17 for raising and lowering keyboard platform 12. Bracket 16 is channel shaped, having vertical sides 18 and a horizontal base 20. Mechanism 17 can be like any of those disclosed in my prior US patent, having a lower pair of links 22 and 24 pivoted to the bottom of respective frame sides 18 by rivets 26 and 28, respectively, and having a channel like upper member 29 pivotally attached to the top of frame sides 18 by rivets 30.

In this example a cam-follower 32 is slideably and rotatably mounted on a horizontal crossbar 34 and runs in a slot 36 formed in platform 12 at the rear thereof, but in front of the pivot axis 37 (Figure 3) running through rivets 14.

The lower portion of cam follower 32, which protrudes downwardly through slot 36, carries a grooved roller 38 that rides on a downwardly extending tapered flange or cam surface 40 formed on the front edge of slot 36. (See Figures 2B and 3). Roller 38 is free to rotate about a stub axle 42 fixed to and carried by the lower end of follower 32.

It will be seen from Figure 3 that the cam-like flange 40 is tapered, having little or no depth at the left-hand 44 end but a substantial depth at the right- hand end 46. Thus, as cam follower 32 is moved from left to right, roller 38 rides on cam flange 40 and lifts keyboard support platform 12 up and backwards about its axis 37 from a horizontal position (shown at 48 in broken lines in Figures 2A and 2B. The weight of platform 12 is therefore taken by follower 32 and crossbar 34.

The second example of a platform support mechanism 60 shown in Figure 4 is similar in some respects to that of Figures 1-3. A bracket 62 is pivotally supported by link arms 64 and 66 in a similar manner to that of the first

example, the platform 66 again being pivotally attached to the sides 68 of bracket 62 by rivets 70. However, in this case, platform 66 has an upturned flange 72 at its rear extremity behind the axis of rivets 70 and flange 72 is of constant height (ie, it does not taper like flange 40 of the first example).

Instead, the sloping cam face is formed by the top surface 74 of the bracket 62, which rises as it extends away from the viewer in Figure 4. In this example, the cam follower 76 is provided with a roller 78 that runs on the edge of flange 72, the upper face of follower 76 simply sliding along the underside of bracket top face 74 guided by a slot 78. Thus, in this case, the cam follower 76 is held in compression by the weight of the platform 66.

It will be appreciated that the mechanism of Figure 4 can be modified to vary the manner in which the follower 76 engages on the platform 66. For example, flange 72 can be eliminated so that an enlarged narrow-edged roller rides directly on the flat surface of the rear of platform 66, which is preferably inclined upwards by about half the maximum angle of platform tilt.

A pair of outside rollers may be added to follower 76 so as to ride on the underside of bracket 74. Also, follower 76 may be provided with a neck flange that retains it in slot 78 in bracket 74, when the platform 66 is lifted.

Figures 5-9 illustrate various alternative possible arrangements of cam followers and cam faces, in each case the frame or bracket is shown at 80, the flanged sides of the platform are shown at 82 and the rivets that pivotally join them together are shown at 84. In each case, a crossbar 86 is employed for the cam follower to move along and be guided, bar 86 joining and being supported by the sides of bracket 80. And, in each case, a second crossbar 88 joining the sides of platform 82 is mounted at an angle to the first crossbar 86 and, thus, forms the cam surface.

In Figure 5, the cam follower 90 includes a rolling cage 92 that embraces both corssbars and has a first pair of rollers 94 that ride on bar 86 and a second pair of rollers 96 that ride on bar 88. In this example, platform bar 88

is mounted in front of the pivot axis of the platform so that cage 92 of follower 91 is held under tension by pressure on platform 82. Moving follower 90 from left to right pulls crossbar 88 toward crossbar 86, raising the front of platform 82.

In the example of Figure 6, the second crossbar 88 is located behind the pivot axis of the platform so that pressure on the platform 82 tends to bring bar 88 towards rather than away from crossbar 86. In this case the cam follower 102 is a sliding fit on bar 86 and carries a single roller 104 that rides on bar 88. Again, sliding follower back and forth along bar 86 causes platform to tilt up or down.

In the example of Figures 7 and 7A, the cam follower 110 is also a sliding fit on bracket crossbar 86 and embraces platform crossbar 88. Crossbar 88 is being arranged in front of the pivot axis of platform 82, so that follower 110 is held in tension by the weight of the platform 82. In this case, a single roller 112 is employed and locking tabs 114 are pivotally attached to the lateral sides of follower 110, being biased away from one another by a spring 116.

Tabs 114 have holes in their faces to accommodate crossbar 86 and serve (under the bias of spring 116) to lock the follower 110 against sideways movement along bar 86. To move follower 110 along bar 86, the user presses locking tabs 114 together and then exerts sliding pressure on the follower 110.

The example of Figures 8 and 8A is a modification of that of Figures 7 and 7A where cam follower 120 carries a central locking tab 122 that has a cam face 124 which pinches bar 86 when moved off-centre to either side. [In this example, platform 88 is of square section.] Thus, unless tab 122 is in either side position, the follower 120 cannot be moved.

The example of Figures 9 and 9a shows the use of square-section crossbars 86 and 88 together with a cam follower 130 that has side locking tabs 132

which function in the same manner as described with respect to tabs 114 of Figures 7 and 7A. In this case, platform bar 88 is located behind the platform pivot axis so that the bars tend to be forced together. In this case, the weight of the platform is borne by a cluster of three rollers 132, the upper pair of which run on bracket bar 86 and the lower one of which runs on platform bar 88.

It will be seen from the above examples that the use of a transversely slidable cam follower riding on a transversely sloping cam face provides a neat and compact way of tilting a keyboard platform. Access to the single control is easy and straightforward and the transverse location of the control (part of the cam follower) provides an immediate visual indication of the angle of tilt. Graduations in terms of degrees of tilt can be readily added to the bracket.

However, those skilled in the art will appreciate that many alterations and additions can be made to the examples without departing from the scope of the invention as outlined above. Edwin Robin Russell by his attorney Paul A Grant 31 May, 1999