Note: Descriptions are shown in the official language in which they were submitted.
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EXTENDABLE K~BOARD SUPPORT ASSEMBLY
TECHNICAL FIELD
This invention relates to computer work stands, in general, and specifically to
extendable keyboard support assemblies for such stands.
BACKGROUND OF THE INYENTION
Keyboard support assemblies for computer work stands are known in ~he art,
such as those depicted in U.S. Patents 4,316,082 and 4,379,429. Such assemblies are
adjustable in certain limited respects, and typically provided a keyboard support surface
having side extending rollers which travel in slots formed in the work stand. Bymanually changing the slot path in which the rollers travel, the support surfaces can be
brought toward the user and into a work orientation.
While the presently available keyboard assemblies work well, and have
lS achieved acceptance in the industry, certain shortcomings prevent them from meeting
all of the market's requirements. One shortcoming is that the degree, or fineness, of
horizontal adjustment provided by such assemblies is limited. Further, adjustment can
be achieved only through relatively awkward manual manipulation of the keyboard
bearing surface.
The keyboard support surfaces of said patents are generally s~lpported in
cantilever fashion which require that the surface be heavy enough to bear the intended
load weight. Resultingly, the operator must lift subst~mtially the entire weight of the
keyboard surface and the load carried thereupon in order to make a horizontal
adjustment. This further reduces convenience and commercial appeal of the product.
Finally, available keyboard support assemblies lack a positive locking feature
which can prevent inadvertent surface movement from jarring or the like. Lack of an
automatic and positive lock can create instability, which likewise is commercially
underdesirable.
DISCLOSURE OF INVENTION
The present invention provides a keyboard support assembly for a computer
work stand which is structurally stable, which can be conveniently and finely adjusted
by the operator and which provides an automatic and positive lock independent ofkeyboard support assembly motion. The keyboard support assembly comprises a sub-plate having a profiled opening extending partially along each side from a rearward end
thereof, and a keyboard support plate slideably mounted over the sub-plate and
covering the profiled openings. The assembly further comprises a pair of lockingdevices for attachment to the keyboard support plate, which depend into the sub-plate
profiled openings. Each locking device has an upward gear rack segment at a forward
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end for selectively meshing with an underside gear rack segment of the sub-plateproximate the profiled opening. The keyboard support surface is thereby substantially
supported by the sub-plate and can be adjusted horizontally in relatively fine
increments. The assembly further comprises means for biasing each locking deviceinto engagement with its sub-plate rack segment, which can be released digitally as the
keyboard support surface is contemporaneously extended and retracted.
It is therefore an objective of the present invention to provide a keyboard
support assembly providing fineness of adjustment, and positive locking between the
keyboard support surface and the supporting structure.
It is a further objective of the present invention to provide a keyboard supportassembly adapted to facilitate easy and smooth extension and retraction of the keyboard
support surface.
Still further, it is an objective of the present invention to provide a keyboardsupport assembly comprising a fully supported keyboard receiving surface.
Further, it is an objective of the present invention to provide a keyboard
support assembly having a minimal profiled dimension, which provides maximum legclearance.
It is a further objective of the present invention to provide a keyboard supportassembly which achieves automatic locking of the keyboard support surface.
2Q Another objective of the present invention is to provide a keyboard support
assembly providing a lock which releases conveniently and contemporaneously with the
movement of the keyboard support surface.
It is a further objective of the present invention to provide a keyboard supportassembly which is economically and readily produced and assembled.
These and other objectives, which will be apparent to those skilled in the art,
are achieved by a preferred embodiment which is described in detail below, and which
is illustrated by the accompanied drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a computer work stand of the type
comprising the subject invention.
Figure 2 is an exploded perspective view of the computer work stand depicted
in Figure 1, illustrating the component parts thereof.
Figure 3 is a partial exploded perspective view of the right side of the
keyboard support assembly, with portions of the keyboard support plate sectioned away
for the purpose of illustration.
Figure 4 is a partially assembled perspective view of the keyboard support
assembly portion shown in Figure 3, with portions of the keyboard support plate
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sectioned away for the purpose of illustration. The keyboard support plate is illustrated
in the fully retracted condition.
Figure 5 is a partially assembled perspective view of the subject keyboard
support assembly shown in subsequence to Figure 4, and portions of the work stand to
5 which attachment is made. Portions of the keyboard support assembly are sectioned
away for the purpose of illustration.
Figure 6 is a side elevation view in longitudinal section of the keyboard
support assembly, showing the operation of the center guide and stop of the assembly
Figure 7 is a side elevation view of the intermeshing gear tooth rack segments
10 of one of the locking levers and the sub-plate comprising the subject keyboard support
assembly.
PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION
Referring to Figure l j a computer work stand 2 is shown generally as
comprising a rectangular pedestal base 4; two spaced apart vertical support columns 6
extending upward from opposite sides of the base 4; a keyboard support assembly 8
positioned to the front of the work stand 2; a video terminal support assembly 10
positioned rearwardly of the stand; and a rearwardly inclined footrest 12 spanning the
base 4 between the columns 6. A rubber anti-skid matting 14 is affixed to the external
20 surfaces of the keyboard support assembly 8, the video terminal support assembly 10,
and the footrest 12.
It will be appreciated that the keyboard support assembly is intended to
receive the keyboard console of a computer or word processing system, and is
adjustable vertically and horizontally to accomodate the operator. The video terminal
25 support assembly 10, which receives a monitor or cathrode ray tube thereupon, can be
ajusted both vertically and rotationally about a horizontal axis, to align with the
operators' line of vision.
Figure 2 illustrates the work stand in an exploded perspecitve view. A
preformed, molded frontal cover 16, constructed of conventional plastics material, has
30 incut bottom legs 18 of reduced sectional dimension, which are insertable into the
upward collar of a premolded pedestal shell 20. A spaced-apart pair of vertical
structural panels 22, of structural plastic, extend upward from the pedestal shell 20.
Each panel 22 has a vertically oriented arcuate gear rack segment 24 therethrough,
located near the base of each respective panel. A horizontal support arm 26 extends
35 from each panel 22 in cantilever fashion, toward the front end of the work stand 2 for
a purpose described below.
A horizontal lead screw 28 extends between the structural panels 22 of the
work station 2, with oposite ends of the screw projecting through the panels 22, each
of which ends being journeled to a rotary actuator crank 30. The lead screw 28 is
further journeled to bottom ends of the scissor-linkages 32. Upper ends of linkages 32
are affixed to a horizontal throughshaft 34 located at the top of the work stand 2. An
extension spring 36 is connected in tension between lower portions of linkages 32, as
S mechanical assists to upward extension.
A bearing plate 38 and a cam plate 40 adjacent thereto are mounted to each
side of the work stand 2, receiving opposite ends of the shaft 34 therethrough.
Actuator knobs 42 are attached to ends of shaft 34, and function to rotate cam plates
40. A video terminal table 44 is provided for location on cam plates 40. The table 44
is thereby rotatably adjustable to align with the line of vision of different operators.
Bracket 46 is provided, inserted through apertures 48 to retain a video terminal upon
the table 44.
With continued reference to Figure 2, a keyboard lift assembly 50 is provided
on each side of the work station 2, and comprises a vertical L-shaped plate 52 to which
a pivoting actuator paddle 54 is attached. A smaller L-shaped pivot plate 56 is
pivotally attached to a lower end of plate 52, linked to actuator paddle 54 by a tie-rod
58. A lock-spring 60 biases the paddle 54 downward and the pivot plate 52 in a
counter-clockwise direction. A guide gear 62 and a lock gear 64 are mounted to the
pivot plate 56 in adjacent relationship. A keyboard lift arm assembly 50 of the type
above described, attaches to each horizontal arm 26 of the work stand, and operates to
selectively bear the gears 62, 64 against the arcuate rack segments 24 of the stand. By
pivoting both paddles 54 upward, the horizontal supprt arms 26 are released and can be
raised or lowered to adjust the height of the keyboard support assembly 8 which is
attached thereto.
Reference will next be made to Figure 3, showing details of the right-hand
portion of the keyboard support assembly 8. It will be appreciated from the foregoing
description of Figure 2, that the left-hand side of the keyboard support assembly 8 is
identically structured to the right-hand side. Therefore, the following specification of
the right-hand portion of the keyboard support assembly 8, is likewise applicable to
identical mirror image and equivalent components comprising the left-hand side of the
keyboard support assembly 8 shown in Figures l and 2.
Figure 3 shows the keyboard support assembly 8 as comprising a keyboard
support plate 66, having a top surface 68 extending between a rearward downturned
end wall 70 and outward facing downward sidewalls 72 (one of which being shown in
Figure 3). The keyboard support plate 65 is slideably mounted over a generally
rectangular sub-plate 74, having a rearward end 76 and a forward end 78. The
keyboard support plate 66 mounts over the sub-plate 74, so as to retract forwardtoward end 78, and extend backward toward rearward end 76. In the retracted
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condi~ion, sidewalls 72 and end wall 70 of plate 66 enclose corresponding side and end
walls of plate 74.
An elongate mounting bracket 80 is attached to the forward corners of the
sub-plate 74, and projects forward therefrom, The mounting brackets 80 have an
5 enclosed rearward end wall 82 and an open forward end 84. An elongate support bar
86 is oriented to extend from the forward end 84 of the bracket 80, backward along the
underside of sub-plate 74. The support bar 86 is configured to provide an upper
overturned plate portion 88 at its forward end for supporting the top surface of bracket
80, and an upper overturn flange portion 90 at a rearward end for supporting thelO underside of support plate 74. Flange portion 90 has a mounting screw 92 extending
therethrough and into sub-plate 74. The forward end of support bar 86 has a U-
shaped slot 94 formed therein~ opening toward forward end 84 of the bracket 80. A
pair of assembly screws 96 ar provided through the overturned plate portion 88, and
extend into sub-plate 74.
The sub-plate 74 is further configured having a profiled opening extending
partially along each side, from rearward end 76. Each opening consists of an incut
corner opening portion 98, and an incut side opening 100. The side opening portion
100 is situated contiguous to the corner opening 98, and extends forward therefrom.
The openings 98, 100 thereby form a single profiled opening along each side of the
sub-plate 74 from the rearward corner toward the forward end thereof. Beginning at
the forward terminal end of each opening 100, the sub-plate 74 is adapted having a
downward directd gear tooth rack segment 102 along each side. As shown, each rack
segment extends along an underside surface of the sub-plate 74 forward to the rearward
wall 82 of the bracket 80 of each side.
At the center of the sub-plate 74 is an elongate center guide slot 104 which
extends longitudinally from a rearward terminal end 106 forward. The slot 104 isdimensioned to receive a downward center guide boss 108 depending from an underside
surface of keyboard support plate 66. A washer 110 and retaining screw 112 are
secured to boss 108, as best seen from Figure 6. Upon abutment of washer llO
against terminal end 106 of the center guide slot 104, further extension of the keyboard
support plate 66 relative to the sub-plate 74 is prohibited.
At end guide boss 114 depends downward from each underside corner of the
keyboard support plate 66, and moves along a side of the sub-plate 116 and retention
screw 118 which function to prevent lateral movement and vertical separation of the
plate 66 relative to the sub-plate 74. Movement of plate 66 is thereby restricted to
reciprocal forward and backward motion as limited by the travel of center guide boss
108 in slot 104.
In addition, each side the keyboard support plate 66 includes a downward
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projecting slotted boss 120, for receiving an upward directed flange 124 of a horizontal
pivot plate 122. An outward end of plate 122 includes a slot 126 for attachment to the
underside of the keyboard support plate 66 by a screw 127. A vertical flange 128depends perpendicularly from horizontal plate 122 and includes a horizontal aperture
130 dimensioned to receive a cylindrical pivot pin 132 therethrough.
A bias spring boss 134 depends from the underside of the keyboard support
plate 66 at a location between the slotted pivot boss 120 and the rearward downturned
end wall 70. Boss 134 is dimensioned to receive a helical bias spring 136 therearound
for a purpose explained below.
With continued reference to Figure 3, an actuating lever 138 is shown
comprising a forward end 139 incorporating an upward directed gear rack segment
140, a rearward trigger paddle 142, and an intermediate elongate portion 141 defining
a longitudinal channel 144. A transverse aperture 146 extends through side wallsdefining channel 144. A boss receiving socket 148 is located in the lever 128 toward
the paddle end 142. Paddle 142 is generally rectangular in plan view as defined by
intersecting side and rear surfaces 143a, 143b, respectively.
Figure 4 illustrates the subject keyboard support assembly 8 in partial
assembled condition with keyboard support surface 66 in the retracted condition relative
to sub-plate 74. Referring to Figure 3 and 4, the keyboard support surface 66 ismounted over the sub-plate 74 such that end and side walls 70, 72 of plate 66 are
contiguous with corresponding end and side walls of the sub-plate 74, and top surface
68 of plate 66 covers the profiled openings of the sub-plate 98, 100. The lever 138
attaches to the underside of the keyboard support plate 66, and depends into theopening 98, 100 of the sub-plate 74. Paddle 142 resides in opening portion 98,
intermediary portion 141 of the lever resides in opening portion 100, ~ld the forward
end 149 of the lever extends forward to position gear rack 140 below corresponding
gear rack segment 102 of the sub-plate 74.
The flange 124 of the horizontal pivot plate 122 is seated within slotted boss
120 of the keyboard support plate 66, and secured thereto by screw 27. The depending
flange 128 extends into channel 144 of the lever 138, and apertures 130, 146 accept
pivot pin 132 therethrough.
Resultingly, lever 138 is pivotally hinged to the underside surface of the
keyboard support plate 66, and is reciprocally moveable in a vertical direction about
pivot pin 132. The helical spring 136, placed in compression by the above assembly,
biases the paddle end 142 downward, and gear tooth rack segment 139 upward into
meshing engagement with gearteeth 102 of the sub-plate 74. The spring bias can be
manually overridden by upward pressure on paddle 142, yet operates to re~stablish a
positive lock between gear racks 102, 139, as soon as pressure is removed.
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Figure 4 illustrates the keyboard support plate 66 in a fully retracted state.
Center guide boss 108, and center guide plate 100, reside within slot 104, and are
moveable backward therealong as the keyboard support plate is exended to the limit of
travel represented by Figure 5. Viewing Figures 1 and 5 in combination, the
assembled keyboard support asembly 8 can be attached to the work stand 2 by aligning
brackets 80 with corresponding arms 26 of the stand. Open ends 84 of brackets 80receive the horizontal arms 26, and the actuator paddles 54 therein, with each
component providing co-aligning assembly apertures 150a, b, and c. Attachment issecured by a screw and nut 152a, b. The horizontal arms 26 each have a fastener 154
which receives the slot 94 of the mounting brackets 80 therearound.
Referring to Figures 4 and 5, opeMtion of the subject keyboard support
assembly 8 proceeds as follows; It will be appreciated that paddles 142 (the right one
of which being shown) are located such that surfaces 138a and 138b of each paddle are
proximate to side and rearward walls 72, 70 of the keyboard support 66, and are
enclosed therby. Specifically, the paddle surfaces 143a, b are distanced from walls 72,
70 such that an operator, by placing his hands palm downward on rearward corners of
sur`face 68, can digitally reach downward around either, or alternatively both, wall 70
and wall 72, and reach beneath paddles 142. Thereafter, upward pressure on paddles
142 can be exerted to p;vot lever 138 clockwise and disengage the gear racks 140 from
corresponding meshing gear racks 142 of the sub-plate 74. Recessed lever paddlesprevent accidental release of the lock mechanism.
From the foregoing, it can be appreciated that as the operator grasps corners
of the support plate 66, and exert upward pressure on the lever paddles 142 beneath
such corners, the operator is simultaneously supporting plate 66 for movement. This
action serves to release the lock mechanism via levers 138 and also supports thekeyboard support plate 66 for easy extension or retraction. By combining the
operators' lock release and slide movements, wasted motion is eliminated.
While the preferred embodiment of the subject invention contemplates locking
levers 138 on both sides of keyboard support assembly 8 only, one locking mechanism
138 can be used if so-desired. It should further be recognized that, in the preferred
embodiment, the locks on both sides of keyboard support assembly 8 must be released
before movement can be effected. Consequently, an operator must manually grasp and
support both corners of the keyboard support plate 66 in order to simultaneouslyrelease the locking levers 138. This serves to require the operator to properly support
the keyboard support plate 66 before attempting a position change, and also serves to
prevent accidental release. Moreover, two-lever release precludes the chance of
pinched fingers during extension.
Release of the paddles 142 of levers 138 causes the forward portions of the
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levers 138 to pivot upward under influence of the bias springs 136. This automatically
brings gear teeth segments 102, 140 into meshing engagement and prevents furtherrelative movement between plates 66 and 74. Figure 7 illustrates the profile of
meshing gcar rack segments 102, 140. It should be noted that the fineness of
S adjustment between plates 66 and 74 is dependent upon the gear rack spacing. The
greater number of gear teeth per inch, the finer the adjustment possible. Also, while
one gear tooth on the levers 138 would suffice for the purpose of the present invention,
multiple gear teeth 140 are recommended for a stronger lock. It will be appre iated
from Figure 7 that each gear tooth is of a truncated pyramid profile. The shallow
angled sides of each gear tooth, preferably of seven degrees (7 ) to the vertical,
facilitates engagement between segments 102, 140 after a position changé, yet provides
a shallow pressure angle to maintain the lock between rack segments.
From Figures 3 and 4, it will be recognized that the resultingly assembled
keyboard assembly 8 is of minimum profiled height. Plate 66 fits over the sub-plate
IS 74, which is enclosed by downturned plate sides 70, 72. Moreover, depending levers
136 operate substantially within the profiled openings 98, 100 of the sub-plate 7~, and
between the confines of sides 70, 72. The thickness of sub-plate 74 is therefore used
to accommodate part of the profiled dimension of the levers 138 to further reduce the
overall profiled size of the assembly. Channel 144 of levers 138 receives depending
pivot flanges 128 of the keyboard support plate therein, which serves to raise the pivot
point (represented by pin 132) of the levers 138, thereby filrther minimizing the
profiled dimension of the assembly.
While the above sets forth the preferred embodiment of the present invention,
the subject disclosure is not to be so limited. Other embodiments which utilize the
teachings herein set forth are intended to be within the scope and spirit of the subject
invention.
