Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A SEATING DEVICE FOR REDUCING
REPETITIVE STRAIN INJURY
Field of the Invention:
This invention relates to a seating device for reducing the risk or the
occurrence of physical discomfort. Such discomfort may arise from
Repetitive Strain Injury which is known to be caused by repeated,
substantially identical movements and in particular arm, wrist or finger
movements over a long period when operating typewriters, computers, and
any manually operable devices, for example, in an office or manufacturing
environment, or, in the home. Additionally, many people suffer back pain
after many hours working in the same position.
Background of the Invention:
Repetitive strain injuries have been recognised for some time as such
and can be experienced by secretaries, for example, typing on a computer
keyboard for long periods, or by people working on production Lines, where
their bodies remain substantially in the same position at their workstations.
In the past, attempts have been made to meet the problem of repetitive
strain injury by making static improvements to chairs, for example, more
comfortable and adjustable and by alterations in the designs of keyboards.
None of these improvements have been sufficiently effective, because, it
is believed, the user remains in a substantially fixed position in relation to
his
work.
SUBSTTTITTE SHEET (RULE 26)
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Repetitive strain injury remains an important cause of absenteeism and,
increasingly, results in litigation.
Summary of the Invention
Therefore it is an object of the present invention to reduce the risk or the
occurrence of the above mentioned physical discomfort, by providing a means
for constantly altering the angles of the user's arms and shoulder joints in
relation to his work station, so that the movements of the various joints and
muscles of the upper limbs (including the wrists and hands), are made
essentially non-repetitive.
1 G According to one aspect of the present invention a seating device is
provided which comprises dynamic means to alter, over an extended period of
time, the position of its user in relation to his work station.
According to another aspect of the present invention there is provided a
seating device for alleviating repetitive strain injuries comprising a seating
arrangement, and dynamic means operable to tilt the seat backwards and
forwards over an extended period of time so that the joints and muscles of the
upper limbs of the user are movable.
The dynamic means whereby the position of the user is altered, is
preferably pneumatic. It may consist of a pillow in the seat cushion, which is
intermittently inflated to alter the height of the user's body. The inflation
cycle should be sufficiently slow as to make the movement imperceptible,
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perhaps 1-2 minutes inflation followed by 1-2 minutes deflation. However,
much longer periods up to 10 minutes or even 20 minutes are possible.
Alternatively or in addition, during the inflation or deflation period of
the seat pillow, a similar pillow in the backrest of the chair may inflate and
S deflate, tilting the user's body towards and away from his work station. It
is
thought, however, that mere tilting alone is unlikely to provide as much
benefit as raising the seat.
The pillows may be divided into separate compartments whose
individual infation may either augment the above actions or add side-to-side
movement.
The average height of the chair seat and the average angle of the back
support may be adjusted by the user for his/her own comfort before using the
device.
By average height of the seat, or average angle of the backrest of a chair
is meant the height at which a user of the chair would set the seat, or the
angle
at which the user of the chair would set the backrest, for their personal
comfort.
Preferably, the above-mentioned movements are continuous. They may
be provided randomly or cyclically. Reciprocal cyclical inflation of seat and
back pillows may be provided by a standard compressor such as that which is
described in Applicants' co-pending British Patent Application
No. 9818318.9. Alternatively, the above-mentioned movements of the chair
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user may be produced mechanically by raising, and lowering, tilting and/or
side-to-side movement of part or the whole of the chair.
Brief Description of the Drawin.~s.
Embodiments of the present invention will now be described by way of
example with reference to the accompanying drawings in which:
Figure 1 is a perspective view of a known secretarial chair;
Figure 2 is a perspective view of one form of secretarial chair in
accordance with the present invention;
Figure 3 is a cross-sectional view of a seating device for use with the
chair of Figure 2;
Figure 4 is a cross-sectional view of a backrest for the chair shown in
Figure 2; and
Figure 5 is a cross-sectional view similar to Figure 3 but including an
alternative seating device.
Description of the Embodiments:
In the description which follows all like parts bear the same reference
numerals throughout the various Figures.
More particularly, and with regard to a known secretarial type chair 1 of
Figure 1, there is provided a padded seat 2 supported on an elongate hollow
leg 3 having five legs extending radially outwardly from one end 3a thereof.
The seating device is movable on rollers 4 across the ground or floor 5. A
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backrest 6 is mounted on the seat and can be fixed, or, slidably mounted for
adjustment of the height of the backrest relative to the seat.
The seat 2 is conveniently in the form of a semi-rigid flat plate 7 which
is mounted on the elongate hollow leg 3 at an end thereof opposite to that end
5 on which the rollers 4 are located. The plate 7 is mounted to extend
substantially radially relative to an elongate central axis 8 of the leg.
The seat 2 (Figures 3 and 4) can be of a resilient foam 9 laid on the plate
7 and is covered with a cloth layer or layers 10 mounted on the seat to
provide
a suitable external surface 11 for the seat.
Various releasable clamping devices are mounted on the leg 3 and the
seat 2 for adjusting the height of the seat relative to the rollers 4, or
alternatively the backrest 6 relative to the seat 2. These clamping devices do
not form part of this invention and therefore are not described further.
The backrest 6 is similarly provided by a foam foundation covered with
a cloth. The backrest is adjustable in height relative to the seat 2 using a
well
known lock arrangement 14 (again not described in detail) which is mounted
on a loop 13 fixed on the backrest 6. The loops 13 are located over arm 12
and the clamping device is unlocked to enable the height of the backrest to be
adjusted relative to the seat by moving the backrest up or down the arm 12.
Figure 2 illustrates an alternative form of seating device which is
substantially as described with reference to Figure l, except that the seat 2
and/or the backrest 6 are of a single compartment hollow pillow construction
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in accordance with the teachings of the present invention. More than one
compartment may be provided in each pillow. Figures 3 and 4 show further
details of the seat 2 and backrest 6 of Figures 1 or 2.
The seat 3 in the embodiment of Figures 3 or 4 comprises seat plate 7
which is connected with a spindle 16 sealingly insertable in a cylinder
housing
17 so that the height of the seat is adjustable pneumatically. Lever lock 18
on
cylinder housing 17 is useful for locking the height of the seat. A
pneumatically adjustable pillow 20 is mounted on the plate and a cloth cover
covers the pillow. The pillow 20 comprises an inflatable volume which is
10 preferably a single compartment but which can be divided into two
independently inflatable compartments 21, 22 located at the back and front
respectively of the seat.
There may be provided in each compartment a slit valve 23 to allow air
forced into the compartment during an inflation phase to leave the
compartment during a following deflation phase. Air is supplied by a
compressor 24. The compressor 24 is preferably located beneath the seat 2 in
an enlarged part 25 of the housing adapted to receive spindle 16. The
compressor may additionally be used for raising or lowering the height of the
seat and/or backrest, but its main task is inflating/deflating the
compartments
in the back and seat pillows using a pneumatic control circuit which can, for
example, be of the type which is disclosed in our co-opending British Patent
Application referred to above. The backrest 6 is also inflatable/deflatable in
a
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similar manner to the pillow of the seat so that it is also tilted backwards
and
forwards in the same alternating time sequence as the seat and preferably
under control of the same control circuitry. That is, when the seat pillow
deflates or the front edge 26 of the seat tilts down the top 27 of the
backrest
tilts forwards so that the backrest 6 moves in sequence with the seat 2
thereby
ensuring that the user's arms move from a different position each time and
any strain is not repetitive. The net result is a considerable reduction in
repetitive strain injury.
Referrii:~; to Figure 5 there is illustrated a further embodiment which is
similar in construction to the embodiment of Figure 3. However, in addition,
a semi-rigid plate 7' is placed above the rigid plate 7. The semi-rigid plate
7'
is inverted and an inflatable pillow 10' is sandwiched between the two plates
7, 7'. A foam cushion or foam seat padding 30 is located on top 31 of the
semi-rigid plate 7', and a cover material 10" is located over the whole of the
seat construction and fixed at 33 beneath the rigid plate 7.
The seat is movable relative to the rigid plate 7 by inflating all the
pillow to raise the seat relative to the fixed plate. When the inflatable
pillow
is formed of one or more compartments, the compartments are inflated
selectively so that the seat device tilts back or forth, or from side-to-side
relative to the rigid plate 7.
The pneumatically controlled movement of the pillow has the effect of
moving the semi-rigid plate 7'. The particular advantage known to exist in
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using the semi-rigid plate 7' in the manner described is a more controlled and
accurate movement of the plate 7' and hence the seat 2.
Therefore, as the seat 2 moves the person occupying the seat is moved
in a manner substantially as hereinbefore described to ensure the person is
not
the subject of repetitive strain injury in their hands, fingers, shoulders
arms,
legs or feet, or back pain by ensuring the person's posture changes slightly
in
one or more directions and the risk of injury through repetitive movement is
reduced.
In any of the embodiments described herein the pillow used in the seat 2
or back-rest 6 can be divided into two compartments with a dividing
membrane extending across the centre of the pillow across the seat 2
intermediate front and back edges of the seat 2. Additional compartments can
be arranged to extend along the whole or part of side edges of the seat to
provide side-to-side movement of the seat or back-rest.
1 S In one alternative embodiment the pillow may have a plurality of
compartments extending radially outwardly from the centre of the seat
whereupon selective inflation of the compartments provides front to back, or
side-to-side movement of seat or back-rest.
Therefore, although the seat pillow has been described as having one
compartment it may have two or more compartments to enable forwards and
backwards tilting. There may be provided one or more additional
compartments which when inflated~'deflated provide side-to-side movement of
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the seat in addition to the forward/backward tilting motion. When arms are
attached to the chair, the arms may be adapted to move up and down with the
side to which they are attached relative to the seat.
The backrest pillow can be similarly constructed so as to tilt from side-
to-side in correspondence with movement of the seat thereby altering the
angles at which the upper limb joints are functioning while working on a
keyboard or workstation.
Any of the constructions described needs only to provide a very slow
cyclic movement requiring small amounts of air, so only a small quiet air
compressor is required which may be of the type disclosed in British Patent
Application No. 9818318.9. but which is quieter because of the very slow
operation thereof..
The movement of the seat 3 and backrest 6 can be by pneumatic rams
such as spindle 16 of leg 3 in the central housing/pillar of the leg.
In a further, alternative embodiment the various movements of the chair
can be controlled electronically by electric motors or mechanically by
rotating
or sliding shafts relative to the central pillar.
The chair movements, particularly the height of the seat, can
alternatively be varied by varying the height of the rollers on which the
chair
is movable, by pneumatic, electrical or mechanical operating arrangements.
Having thus described the invention by reference to specific
embodiments, it is to be well appreciated that the embodiments are in all
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respects exemplary and that modifications and variations thereto are possible
without departure from the spirit and scope of the invention. For example,
rather than using a pillow or cushion with selectively inflatableideflatable
compartments to achieve the desired motion of the seat and/or backrest,
electromechanical or hydraulic/pneumatic actuators could be employed to
move the basic seat/backrest surfaces.
