Note: Descriptions are shown in the official language in which they were submitted.
CA 02312868 2000-06-O1
Description
PORTABLE SCALES
The invention relates to scales comprising an electric force transducer for
measuring a
force due to weight and an indicating device for indicating the force due to
weight.
Electric scales are often used in oWces and in kitchens. The force transducer
is situated
in a region between a support frame and what is referred to as a weighing pan
or a seat for
a weighing pan of this kind. When the weighing pan is loaded with an article,
a force due
to weight can be measured by means of the force transducer if the base frame
is placed on
a flat surface.
One disadvantage of l.~now~n scales is that they often project out to a
considerable extent.
Scales of this kind therefore cannot be taken along when travelling as they
take up a lot of
space.
The known scales are also limited in terms of design. They often have a base
frame in the
form of a housing with a square or round base surface. A movable weighing-pan
support
is mounted thereon, with a force transducer extending between the base frame
and the
weighing-pan support.
GB-A-2 184 852 describes scales comprising a pair of components of essentially
identical
design and shape. Each component has a platform, a base and a plate which can
be
deformed by the load to be weighed and is provided with at least one strain
gauge. The
components are hinged together by means of devices allowing for movement
between an
unfolded position and a folded position.
FR-A-2 700 849 describes a device comprising a plurality of modules which are
pivotably
coupled together so that they can assume the geometric shape of a hinged
support. Each
module is provided with at least one measuring sensor, and a measuring
function can be
obtained by the measuring sensors in combination.
US-A-5 414 225 describes a portable weighing device comprising two laterally
offset,
electrically connected and rigidly aligned weighing modules. The scales shown
there
allow for convenient weighing of disabled persons in a wheelchair supported by
two front
wheels and two main wheels.
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2
The scales known from the aforesaid documents of the prior art once again have
the
disadvantage that they project out to a considerable extent.
The aim of the invention is therefore to provide scales which are easy to
iransport and
take up only a little space.
This problem is solved according to the inv~tion by the subject matter of the
independent
claim. Advantageous developments will be clear from the dependent claims.
The problem is solved according to the invention by two force transducers
which can each
be acted upon independently of one another by a force due to weight, the force
transducers being connected together in such a manner that one force
transducer is
movable relative to the other. The force transducers can be rotated and/or
displaced in
translation relative to one another.
According to the basic concept of the invention, both the basic housing and
the weighing-
pan support of the blown scales are superfluous. If two or more independent
force
transducers are used, these then advantageously take over the function of
stable support of
the goods to be weighed on a base surface.
The term force transducer as used in the sense of the invention therefore
refers to a device
which rests on a contact surface and measures a force due to weight departing
from an
article supported on the device and acting on the contact surface.
This results in the advantage that the force transducers or their supporting
arms can be
collapsed if no measurements are being carried out, thus making the scales
easy to
transport in the collapsed state. According to the invention, the axis of
rotation can
extend substantially perpendicularly to the directions of the principal extent
of the
supporting arms. The supporting arms can thus be hinged like the arms of an
angle.
The force transducers can then constitute at least three bearing points for an
article, the
force due to weight of which is to be measured. The article to be measured
stands stable
on these at least three bearing points, thereby giving a reliable measuring
result. The
stability of the scales according to the invention can be increased by
providing safety
cams in the region of the supporting arms, these additionally supporting the
scales if they
tilt about the contact points of the force transducers.
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The scales according to the invention also advantageously have a reset button
for aligning
the scales in an initial state and/or for switching on the scales. The scales
can be brought
into a defined initial state in which they are adjusted to zero prior to a
weighing process
by means of a reset button of this kind. The weight of varying articles can
thus also be
determined in a lulown manner, e.g. a plate placed on the scales, from which
food is
removed. The weight of each individual item of food removed can be precisely
determined in this manner if the scales are always "zeroed" prior to the
removal of parts
of the food.
In one particular embodiment, the scales are so flat that, as the food on a
plate increases,
they can be arranged in the region below the plate without coming into the
immediate
vicinity of the eater. E.g. force sensors made of pressure-sensitive foil
inserted into foil-
like force arms can be used to this end. Scales which are easy to transport
and are
relatively inconspicuous in use can be produced in this manner.
Alternatively, almost point force sensors can also be provided in contact
points of the
scales. When using piezoelectric actuators, this results in scales with high
measuring
accuracy.
The scales can also have an evaluation unit with a substance data base.
Measuring results
can then be converted directly into desired variables, e. g. volume or energy
content.
Coupling to external computers is furthermore provided for, e.g. in order to
feed
measuring results to the computers or to maintain data provided in the scales.
Two embodiments of the invention W 11 now be described in more detail with
reference to
the accompanying drawings, in which:
Figures 1 to 3 are three-way views of a first set of scales according to the
invention in
the collapsed state;
Figure 4 shows the scales of Figures 1 to 3 in the unfolded stated, ready for
operation;
Figure 5 shows the scales of Figure 4 with a plate placed thereon;
Figures 6 and 7 show another set of scales according to the invention, and
Figures 8 and 9 show another set of scales according to the invention.
Figures 1 to 3 are three-way views showing a set of scales 1.
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The scales 1 are composed of a base 2 and two supporting arms 3 and 4
rotatably mounted
on the base 2. The supporting arms 3, 4 are pivotably secured to the base 2 by
means of
pivot axes 5, 6 extending perpendicularly to the direction of the extent of
the supporting
arms 3, 4. Figure 4 shows the scales 1 with supporting arms 3, 4 pivoted away
from the
base 2.
Strip-shaped force transducers 7, 8 and 9 are provided on the top surface of
the supporting
arms 3, 4 and of the base 2. The force transducers 7, 8 and 9 can be in the
form of, e.g. a
pressure foil or deformation-measuring devices, in which mechanical
deformation is
converted into a corresponding electric signal.
An electric evaluation circuit not shown here is provided in the interior of
the base 2, adds
up the forces measured by the force transducer 7, 8 and 9 and indicates the
result on a
display 10 provided on the base 2. A reset button 11 is mounted on the base 2
for
resetting the state of the scales.
As will be seen most clearly in Figures 1 to 3, the scales 1 take up only a
little space in the
collapsed state, i.e. when the supporting arms 3, 4 are pivoted against the
base 2.
Figure 5 shows the scales 1 of Figures 1 to 4 in a state in which they are
loaded by a plate
12 shown here by means of broken lines. As will be seen particularly clearly
from this
view, a base ring 13 of the plate 12 loads the force transducers 7, 8 and 9 at
contact points
14, 15 and 16. The contact forces measured there are added together and
indicated on the
display 10.
As will furthermore be particularly clear from this view, the plate 12 stands
stable on the
three contact points 14, 15 and 16 so that cutting and eating is also possible
on the plate
12. The base 2 projects only a little beyond the edge 12 of the plate, as a
result of which it
is only accessible to the user of the plate 12. The presence of the. scales 1
under the plate
12 is almost invisible to onlookers.
Figure 6 shows another set of scales 20 with a base 21 and only one single
pivot arm 22
which is pivotable relative to the base 21 by means of a pivot axis 23
extending
substantially perpendicularly to the direction of the extent of the base 21 or
the pivot ann
22. Respective line force transducers 24 and 25 are provided in the region of
the pivot
arm 22 and the base 21.
CA 02312868 2000-06-O1
Figure 7 shows the scales 20 of Figure 6 in the ready-to-use state with a
plate 26 placed
thereon, resting on the force transducers 24 and 25 by means of a base ring
27. It thus
contacts them at contact points 28, 29, 30 and 31.
The weight measured by the force transducers 24 and 25 is indicated on a
display 32
provided at an end of the pivot arm 22 remote from the pivot axis 23. A reset
button 33
serves to actuate the scales 20.
In a variant of the scales 20 according to the invention not shown here, the
weight
measured by the force transducers 24 and 25 is indicated on a display 32
provided in the
region of the end of the pivot arm 22 situated at the axis of rotation 23.
Figures 8 and 9 show another set of scales 20 similar in design to the scales
20 of Figures
6 and 7. Identical components have been designated by the same reference
numerals.
The scales 20 have force-measuring supports 34, 35 and 36 which take over the
function
of the force transducers 24 and 25 of the scales 20 of Figures 6 and 7. One
force-
measuring support 34 is mounted in the region of the pivot axis 23, while the
other iwo
force-measuring supports 35 and 36 are mounted at the end of the base 21 or at
the end of
the pivot arm 22, as will be seen most clearly in Figure 8.
In a variant of the scales 20 according to the invention not shown here, the
weight
measured by the force transducers 24 and 25 is indicated on a display 32
provided in the
region of the end of the pivot arm 22 situated at the axis of rotation 23.
Figure 9 shows the scales 20 of Figure 8 in the ready-to-use state with a
plate 26 placed
thereon, resting on the force transducers 24 and 25 by means of a base ring
27. It thus
contacts them at contact points 28, 29, 30 and 31.
The sum of the forces due to weight determined by the force-measuring supports
34, 35
and 36 is indicated on the display 32.
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LEGEND
I scales 21 base
2 base 22 pivot arm
3 supporting arm 23 pivot axis
4 supporting arm 24 force transducer
pivot axis 25 force transducer
6 pivot axis 26 plate
7 force transducer 27 base ring
8 force transducer 28 contact point
9 force transducer 29 contact point
10display 30 contact point
11reset button 31 contact point
12plate 32 display
13base ring 33 reset button
14contact point 34 force-measuring
support
15contact point 35 force-measuring
support
16contact point 36 force-measuring
support
20scales
