Tiltable and/or rotatable support for display device

A tiltable and/or rotatable support for a display device which includes a locking mechanism 19, 20, 21, 22, 23, 24 operable to lock the support in a selected tilt position while still permitting swivel adjustment. The support may be provided as a stand-alone unit or formed integral with the base of the display device.

FIELD OF THE INVENTION 
The invention relates to a tiltable and/or rotatable support for a unit 
such as a display device. 
BACKGROUND OF THE INVENTION 
Description of the Prior Art 
The IBM 6580 Display Station (IBM is a registered trade mark of 
International Business Machines Corporation) includes a display module 
which may be swivelled and/or tilted by an operator to adjust the viewing 
angle. The base of the display module has a central ribbed portion which 
is shaped to present a spherically contoured convex surface. This module 
is supported on a plinth which has a central spherically contoured concave 
surface which mates with the contoured surface on the underside of the 
module. The two surfaces are slidable, one over the other, to rotate 
and/or tilt the display module on the plinth. A shaped key-piece extends 
from the center of the convex surface on the underside of the module 
through an elongated aperture extending diagonally across the concave 
surface in a direction from front to back of the plinth. The shape of the 
key-piece serves to hold the module in place on the plinth while 
permitting tilting of the module within the limits dictated by the 
key-piece movable within the confines of the elongated slot. Rotation of 
the module is limited by a projecting lug extending upwards from the base 
into the spherical convex surface of the module where it engages ribs 
positioned to define the permitted rotational movement of the module. Wing 
pieces extend down from each side of the convex surface of the module to 
contact the plinth to provide lateral support for the module and to limit 
vibration. Further details of the construction of the tilt and/or rotate 
feature of the display module are to be found in the co-pending European 
Patent Application No. 81101628.6, and corresponding Ser. No. 159,553 
filed on June 16, 1980 now U.S. Pat. No. 4,365,779, now U.S. Pat. No. 
4,377,849. 
IBM Technical Disclosure Bulletin Vol. 23, No. 7A, Dec. 1980, pages 2859/60 
entitled "Swivel and tilt mechanism for display unit' by S. Futatsugi and 
M. Koboyashi, describes a mechanism similar to that incorporated in the 
IBM 6580 Display Station but additionally having a locking mechanism for 
clamping the display module, or cabinet, on the plinth, or pedestal, in 
the selected tilted and rotated position. The locking mechanism consists 
of a T-shaped shaft, or stopper, mounted for axial movement in the central 
hole in the concave spherical surface of the plinth and extending through 
a diagonally positioned elongated slot running from front to back across 
the convex surface of the underside of the display module. Although 
axially movable, the T-shaped shaft is otherwise fixed in a relation to 
the plinth with the cross-bar of the shaft aligned parallel to the front 
edge of the plinth. When assembled, the cross-bar of the shaft is only 
aligned with the elongated slot in the display module when the latter has 
been rotated through 90.degree. with respect to the plinth. The T-shaped 
shaft serves therefore to secure the module to the plinth in all normal 
viewing positions. The module may be removed from the plinth if desired by 
rotating through 90.degree. and lifting, allowing the cross-bar of the 
shaft to pass through the elongated slot. The cross-piece of the shaft is 
provided on its underside with a hard rubber layer which is normally held 
in frictional contact with the inside surface of the module base by means 
of a spring attached to the other end of the shaft exerting a force 
downwards into the plinth. When it is desired to adjust the display module 
swivel or tilt position, the clamp is released by means of a cam operated 
mechanism which lifts the shaft and thus the locking brake, constituted by 
the rubber coated cross-piece, from engagement with the inside surface of 
the base of the display module. 
SUMMARY OF THE INVENTION 
The present invention provides an improved tiltable and/or rotatable 
support suitable for a display device which may be in the form of a 
separate unit on which the display device is placed or alternatively, as 
in the prior art examples, with the top of the unit integrally formed as 
the base of the display device itself. The same basic principle is used as 
in the prior art in as much as tilt and swivel adjustment is achieved by 
means of two spherically contoured mating surfaces sliding one over the 
other. A locking mechanism is also provided but this differs from the 
prior art in that it functions to lock the unit in a selected tilt 
position while still permitting rotational swivel adjustment. The facility 
of being able to adjust the viewing position of the display device in two 
stages is a considerable advantage over the prior art especially when 
dealing with relatively heavy units such as large screen display devices. 
Additionally, by appropriate selection of materials, the rotational 
stiffness of the unit when in its locked position can be controlled. 
In order that the invention may be fully understood, a preferred embodiment 
thereof will now be described with reference to the accompanying drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT 
A tiltable and/or rotatable stand according to the invention shown in the 
figures, consists of two main components, a base member or plinth 1 and a 
top member or platform 2 upon which a display device 3 or some other unit 
is supported. The construction of the stand is such that the platform is 
rotatable through 90.degree. in either direction from the front-facing 
position, and tiltable from the horizontal 5.degree. in an upwards 
direction through to 20.degree. in a downwards direction. FIG. 1 shows the 
stand with swivel adjustment and FIG. 2 shows it with tilt adjustment. 
The two components 1 and 2 are held together by means of a locking 
mechanism extending through apertures in both components and operable by 
means of a lever 4 (FIG. 4) projecting through, and movable along a 
horizontal arcuate slot 5 in the plinth 1. The lever 4 carries a knob 6 
shaped to enhance ease of operation. The arrangement according to the 
invention is such that with the knob 6 in its extreme left hand position 
in slot 5, the locking mechanism is released so that the platform 2 is 
free to rotate, or swivel, and tilt, or pivot, with respect to the plinth 
1. With the knob 6 in its extreme right-hand position in slot 5, as shown 
in FIGS. 1 to 4, the locking mechanism is engaged so that thereafter the 
platform 2 is locked against tilting, or pivoting, but still adjustable by 
rotation, or swivelling. The stiffness of swivel adjustment can be 
controlled by appropriate selection of materials, and in the preferred 
embodiment, is arranged to be fairly stiff in order to prevent inadvertent 
movement of the display caused, for example, by accidental contact. 
A detailed description of the construction and operation of the support 
stand will now be given with reference to the exploded diagram shown in 
FIG. 4. The plinth 1 is formed as a rectangular base member having a 
central spherically contoured concave annular surface 7 surrounding a 
central circular aperture 8. The platform 2 is similarly formed as a 
rectangular top member having a central spherically contoured surface 9 
matching the concave surface 7 and having a diagonal elongated slot 10 
extending therethrough from the front to the back of the platform. In one 
form of construction according to the invention, the top member may be 
placed in direct contact with the base member with the convex surface of 
the base member. In the embodiment shown in FIG. 4, the plinth 1 and 
platform 2 are formed by moulding in structural foam which ensures that 
the device is sufficiently robust to support a heavy unit such as a 
display device but which does not have good wear and low friction 
properties desired. Accordingly, in the preferred embodiment described 
with reference to FIG. 4, the two contoured surfaces are additionally 
provided with low friction surfaces. Thus, an annular bearing surface 11 
of low friction hard wearing material, with a correspondingly contoured 
profile to that of surface 7 is provided on the surface located between 
raised concentric rims 12 and 13 themselves formed during the moulding of 
the plinth. The annular bearing surface 11 is secured by a number of 
integral shaped clips 14 which snap-fit into correspondingly positioned 
holes 15 in the surface 7. The elongated slot 10 in the surface 9 prevents 
a similar annular bearing surface being used for the platform and 
accordingly two separate bearing surfaces 16 are provided located one on 
each side of the slot. The bearing surfaces are secured by further 
integral shaped clips 17 which snap-fit into correspondingly positioned 
holes 18 through the surface 9. With the plinth 1 and platform 2 mounted 
together as shown in FIG. 3, the mating bearing surfaces ensure smooth and 
easy adjustment of the stand by an operator. 
The platform is secured to the plinth by means of a brake member 19 secured 
to, but free to rotate on, the free end of an axially tapped shaft or 
spindle 20 extending from the lever 4 and passing through a central hole 
in a circular cam device 21 and elongated slot 10. The cam device is held 
as a press-fit in aperture 8. The brake member is secured to the shaft 20 
by means of a bolt and retaining washer 22 which, when screwed fully home, 
provides clearance to enable the brake member to be rotated on the end of 
the shaft. 
The free end of a lug 23 integral with and extending backwardly and 
downwardly from the brake member 19 passes through elongated slot 10 and 
into an arcuate slot 25 formed in the inner region of surface 7. The brake 
member 19 is therefore constrained to rotate with the platform 2 during 
swivel adjustment, the amount of adjustment of the platform being 
determined by the length of arcuate slot 25 within which the lug 23 
slides. Further, the amount of tilt adjustment is determined by the length 
of elongated slot 10 in the platform which is slidable forwards and 
backwards about the fixed axis of the shaft 20 and the lug 23. Two brake 
pads 24 are secured to the underside of laterally extending portions of 
the brake member 19 to lie above portions of the inside surface 26 of the 
platform located on each side of and extending parallel to, the slot 10. 
The underside of the cam device 21 has two identical camming surfaces 27 
over which cam followers 28 on lever 4 ride as the lever is moved about 
its pivot along slot 5. The arrangement of the mechanism is such that 
movement of the lever 4 from its extreme left-hand position to the extreme 
right-hand in slot 5 is accompanied by movement of the cam followers along 
the camming surfaces, the profile of the latter being such that the shaft 
20 is drawn axially down through the apertures by a predetermined amount. 
The relative size of the various component parts forming this brake 
mechanism are chosen so that with the lever 4 in the extreme left-hand 
position the brake pads 24 are clear of, or only make light contact with, 
the inner surface positions 26 but with the lever in the extreme 
right-hand position the brake pads are drawn hard into frictional 
engagement with the portions 26 to clamp the platform 2 firmly in the 
selected tilt position. Since the brake device 19 can rotate with the 
platform 2 and because the friction between the mating smooth contoured 
surfaces of the platform and plinth in considerably less than the friction 
between brake pads 24 and the inside surface 26 of the platform rotational 
adjustments can be made when the tilt adjustment is locked. This is 
especially the case in this preferred embodiment where additional low 
friction bearing surfaces have been provided. 
Several variations of the support stand can be made without departing from 
the invention. First, as explained above, the additional bearing surfaces 
can be dispensed with provided the wear characteristics and friction 
between the two mating contoured surfaces are suitable. The support need 
not be made as a stand-alone unit, but can be integrated into the 
structure of the display device itself with the platform or top member 
formed from the base of the unit. The curvature of the mating surfaces can 
be reversed with the plinth having a convexly curved contoured surface 
mating with a concavely curved contoured surface on the platform. Further 
the locking mechanism can be inverted with the brake member acting on the 
lower surface of the plinth and the lever operating in a slot in the top 
member or platform. Other variations in specific details of construction 
will also be apparent.