Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a weight measuring
device, more particularly, to a portable digital weight
measuriny device which is suited to carry in a briefcase or
suitcase~
Overweight has been a sexious problem not only for
the person who is suffering from it bu~ also for the whole
society. Both diet and exercise take important roles in
striving to regain and/or maintain physical fitness. For this
reason, weight measuring devices are indispensable for those
suffering from overweight. Weight measuring devices are
generally readily available at home, but this is not the case
at hotels or motels. Unfortunately, most commercially
available weight measuring devices are too voluminous and also
too heavy to carry them in a briefcase or suitcase. Accordingly,
most weight watchers usually ignore their weight dur~ng
travelling in which people are apt to have more foods and
beverages but less exercise.
There have been proposed and used diverse kinds
of weight measuring devices, which may be represented by
bathroom scales which ha~e spread to almost every family in
North America. Most of them have a mechanically driven
analogue-type display system. Use of an electrical display
system or even an electrical digital display system has
been lately proposed, for example, in the following
publications:
Canadian Patents: 898,285 Provi et al 4/18/72
964,679 Yamagiwa 3/18~75
U.S. Patents: 3.381,767 Rairigh 5/07f68
~3,469,645 Provi et al g/30/69
3~709,3Q9 Williams Jr. et a~ 1/09/73
3,838~744 Tanji 10~1/74
3,853/191 Yamigiwa 12~10f74
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U.S. Patents: 3,894,594 Oejelid 7/15/75
3,967,690 Northcutt 7/06/76
"Popular Science" page 184, May, 1977
In one aspect of this invention there is provided a
portable digital weight measuring device comprising: a base,
a platform spacedly placed over the base so as to be depressed
when an object is placed onto the upper surface of the platform
and to automatically regain its normal position when the object
is remo~ed therefrom; a plurality of strain gauges or piezo-
lG electric transducers installed betweerl the base and the platformin such a manner that said strain gauges or piezoelectric
transducers con~ert a downward movement of said platform into
electrical signals; a summing system including an operational
amplifier adapted to sum the electrical signals from the strain
gauges or piezoelectric transducers to an electrical signal
proportional to the total weight imposed onto the platform,
an A-D converter adapted to convert the summed electrical
signal to a digital signal; means to display the digital signal
from the A-D converter, said means being located in the top
surface of the measuring device; and a power source electrically
and disconnectably integral to the strain gauges or pie~o-
electric transducers, summing system and the display means.
In anothe~ aspect of this invention there i5 provided
a porta~le digital weight measuring device cvmprising: a base
being generally rectangular; a platform extending over the base
and having a raised portion along the top end thereof, sa~d
xaise~ portion having a spacedly arranged three openlngs there-
through; and spacedly placed over the base so as to be depress~d
when an ok~ect is place~ onto the upper surface of the platform
30 and to automatical~y regain its norma~ p~sition when the ob3ect
is remcved therefrom; four s~rain gauges between the base and the
platfonm and in the four corners thereof, said strain gauges
--2--
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being adapted to convert a downward movement of said platform
into electri~al signals; a summing system including an
operational amplifier adapted to sum the electrical signals from
the strain gauges to an electrical signal proportional to the
total weight imposed onto the platform, a first means to input
an electrical signal into the opexational amplifier to allow
the zero adjustments for the system, said first means being
operated by a disc manually operably protruding through one
of the openings in the raised portion of the platform and a
second means adapted to adjust the operational amplifier
depending on required unit of display, said second means
being operated by a switch means manually operably installed
thxough one of the openings in the raised portion of the
platform and an A-D converter adapted to convert the summed
signal to a digital signal; a LED display adapted to display
the digital signal from the A-D converter, the display being
readily installed in the other opening in the raised portion of
the platform; and a battery installed within the device and
being electrically and disconnectably integral to the strain
gauges, summing system and the display.
The advantages derived from the present invention are
numerous. The porta~le digital weight measuring devices of
the present invention can be made so compact and light that
they can be carried in a briefcase or suitcase during
travelling, thereby allowiny people to watch their weight
during that per~od. W~ight is digitally displayed in a large
size, thus it is possible for almost every person to read it
out w~thout wearing eyeglasses~ When a ~ED ~light emitting
diode) display is employed, it enables a person to use that
device without light at night or in dar~ places. Other
advantag~s and aspects of this invention will become apparent
by readin~ the following detailed description of an embodiment
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of this invention while referring to the attached drawings,
in which:
Figure 1 is a top plan view of a portable digital
weight measuring device according to the present invention;
Figure 2 is a side elevational view of the device;
Figure 3 is an enlarged cross-sectional view showing
installation of a strain gauge; and
Figure 4 is a block diagram of the circuits for
actuating a display as used in this invention.
Referring now to Figures 1, 2 and 3, a rectangular
base 1 (shown in Figure 3 only) is supported by four corner
legs. A platform 2 of an inverted rectangular box shape extends
over the base 1. The platform 2 has along its one end a raised
portion 3 which accommodates a KG-LBS switch 4, a LED display
5, a zero adjustment disc 6, a summing system ~which will be
explained below in detail) and a battery (not shown) therein.
The KG-LBS switch enables a user to display his weight
in either one of the weight units as he chooses. In this
embodiment, a 7 segment LED display is used, but any suitable
digital display known in the art may be used. As described
above, LED displays are preferred as they can be read without
light at night or in dark places. When digital displays
other than the light emitting type are used, it is desirable to
provide an illumination lamp for reading at night or in dark
places. The zero ad~usbment disc 6 allo~s a -ser to adiust the
display at zero before every use. This adjustment is very
important, but not essentia~, as the device is susceptible of
being affected by physical shoc~s and volt2ge of the electrical
source.
3~ Four strain gauges 7 known per se in the art are
lo~ated between the base 1 and the platform 2 at four corners
of the device~ Any suitable piezoelectric transducers, which
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are known per se in the art, can be used in place of the strain
gauges 7. As b~st seen in Figure 2, the strain gauges 7 are
mounted on a load cell. The load cell is formed by an upper
leaf spring 11 and a lower leaf spring 12. The upper leaf
spring 11 is detachably secured at one end thereof to the
platform 2 by means of a locating pin 13 which allows removal
of the platform 2 from the device. The lower leaf spring 12
is fixedly secured at one end thereof to the base 1 by a
rivet 14. Both upper leaf spring 11 and lower leaf spring 12
are fixe~ly joined together at the free ends thereof by a
rivet 15. A strain gauge 7 is mounted onto the upper surface
of the upper leaf spring 11. The leaf spring arrangement
allows the s~rain gauge 7 to output an electrical signal
proportional to the deformation of the upper leaf spring 11
and further allows the platform 2 to regain its normal
(unloaded) position.
In Figure 4, a block diagram of the circuits is
illustrated. Numeral 20 indicates a summing system of this
invention, which includes an operational amplifier 21, a zero
adjustment means 22 which is manually operated by a user
through the zero adjustment disc 6 to send an appropriate amount
o electrical signal to the operational amplifier 21 so that
the display 5 shows zero when the platform 2 is free of load.
The summing system 20 further includes an A-D converter 23
known per se in the art which con~erts a summed electrical
signal sent from the operational amplifier 21 to a digital
signal. The operational ampli~ier 21 known per se in the art
serves to sum the electrical signals from the four strain gauges
7 to an electrical signa1 proportional to the total weight
3p imposed o~to the platform 2. The operational amp~ifier 21
has two ~ifferent amplification degrees whioh are manually
switched from o~e to the other through the ~5-1BS switch 4 in
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order to display the weight of a user in either one of the
weight units.
The strain gauges 7 are connected in series. A
battery 24 is used as an electrical source, but an AC converter
can be employed so that an external AC main input can be used.
Upon operation, the KG-LBS switch is turned to either
side as desired. The switch 25 is turned on and the zero
adjustment disc is manually rotated in either one of the
directions until the LE~ display 5 shows zero. The device is
now ready for measuring the weight of the user. When he
places his feet onto the platform 2, the platform 2 is
depressed thereby deforming the upper and lower leaf springs
11, 12. The degree of the deformation of each upper leaf spring
11 is measured by its respective strain gauge 7 and converted
into an electrical signal. These electrical signals then travel
to the operational amplifier 21 which sums these signals into
an amplified electrical signal, which is then fed into the ~-D
converter 23 where the electrical signal is converted into a
digital signal. This digital signal is thereafter displayed
at the LED display 5.
While the application describes the use of strain
gauges or piezoelectric transducers, other transducers such as
conductive foam sensors are also useable in the present
invention.
