CA2411634A1 - Weigh scale having unitary platform and load cell structures - Google Patents
Weigh scale having unitary platform and load cell structures Download PDFInfo
- Publication number
- CA2411634A1 CA2411634A1 CA002411634A CA2411634A CA2411634A1 CA 2411634 A1 CA2411634 A1 CA 2411634A1 CA 002411634 A CA002411634 A CA 002411634A CA 2411634 A CA2411634 A CA 2411634A CA 2411634 A1 CA2411634 A1 CA 2411634A1
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- Prior art keywords
- scale
- load
- platform
- strain
- display
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G21/00—Details of weighing apparatus
- G01G21/28—Frames, Housings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G21/00—Details of weighing apparatus
- G01G21/22—Weigh pans or other weighing receptacles; Weighing platforms
Abstract
A body weigh scale that is formed of a fiber-filled, polyester thermosetting polymer material that is sufficiently rigid so that it may house strain-gauge load cells therein, and yet not significantly deflect under load. The fiber-filled, polyester thermosetting polymer material provides an attractive surface after molding. The fiber-filled, polyester thermosetting polymer material has extremely low shrinkage rates so that the outer pattern and shape of the scale is not affected by the forming of very thin cross-sections adjacent to thick cross-sections. In addition, the fiber-filled, polyester thermosetting polymer material is sufficiently rigid to permit a body weigh scale to be constructed having a low profile with integral load-receiving platform and strain-gauge load cell receptacles. The rigidity of the fiber-filled, polyester thermosetting polymer material provides sufficient structural support for operation of she strain-gauge load cells without deflection of material at the receptacles.
Description
WEIGH SCALE HAVING UNITARY PLATFORM AND LOAD CELL
STRUCTURES
FIELD OF THE INVENTION
The present invent:.ion relates to weigh scales, and more particularly t:o body wE:~igh scales.
BACKGROUND OF THE INVENTION
Scales are device:; that are used to determine the weight of an object by measur:i_ng the gravitational pull exerted on that object. Scales a~~e commonly used to determine the physical amount or quarv.t:ity of an item, such as a foodstuff, for example.
Body weigh scales can be found in many contemporary homes, usually in a bai::l-:room. For th:LS reason, the body weigh scales are often calleca "bathroom sca:Les." In general, body weigh scales include a platform onto which a user steps, and the user's weight is ttnen displayed. Body weigh scales allow a user to monitor his c::~r her weight, usually before or after a shower, or just after vraking up in the morning.
Many body weigh scales are mer_hanical, spring scales. In a spring scale, a plattorm is connected to a spring, which either stretches or corcupresses to balance a load (i.e., a 1 _ person) placed on the ~:~latform. A needle, whose position depends on the extent t:o which the sp:r:ing is stretched or compressed, indicates i::he weight of the load. Some mechanical scales include a pulse counter and a digital display upon which the user' s weighs::. is shown.
Electronic body wE~i.gh scales utilize electricity to measure loads. Electr<unic. scales are faster, and generally more accurate, than thE::~ir mechanical counterparts. A common type of electronic sca:l.e uses a strain-gauge load cell. This type of scale has a pla:~t:form supported by a column, with a strain gauge or gauges fused to the column. A strain gauge is a thin wire whose elect:ric:a:1 resistance changes when the wire is stretched or compre~-used. When a load is placed on the platform, the column arid strain gauge are compressed. The corresponding change irn resistance of the strain gauge can be used to determine the ~:~erson's weight. The column of the strain-gauge load cell ~r:ust be mounted in a :rigid structure that does not deflect under the load on the body weigh scale.
Otherwise, some of the strain of the object being weighed may be released as strain _.n the structure. By using a rigid structure, the weight <:~f the objf=ct being weighed (e.g., a person) is transferred directly to the strain-gage load cell or cells, so that the <:oiumn may fully compress relative to the rigid structure an~:~ the strain gages in 'the load cell may provide accurate =Lnforrnation about the weight on the body weigh scale.
Although strain-g~~uge load cell scales work well for their intended purpose,. there is a problem with their manufacture. For many c:~ontemporary strain-gauge load cell scales, it is desirable that the upper surface, or load-receiving platform, be decorative, such as a glass top, a faux marble top, a natural ruaterial such a;s stone or marble, or similar decorative sur:f:aces formed from a plastic material.
For glass load-receiving platforms, it has not been possible to form the load-recei~~~ing platform integral with the structure for receivincx the column of the strain-gauge load cell, because glass does not allow much flexibility in shape-forming in its manufact;.ure. Thus, the structure for receiving the column of the stra:i.n-gauge load cell is typically provided in a base that. is separate from the load-receiving platform and that is connected, f:or example by gluing, to the load-receiving platform. Aro. example of a scale having a separate base and load-receivinc:3 platform st=ructure is shown in U.S.
Patent Number 5,955,70'... to Germanton. That patent shows a load-receiving platforrn that fits over a U-shaped frame or base.
STRUCTURES
FIELD OF THE INVENTION
The present invent:.ion relates to weigh scales, and more particularly t:o body wE:~igh scales.
BACKGROUND OF THE INVENTION
Scales are device:; that are used to determine the weight of an object by measur:i_ng the gravitational pull exerted on that object. Scales a~~e commonly used to determine the physical amount or quarv.t:ity of an item, such as a foodstuff, for example.
Body weigh scales can be found in many contemporary homes, usually in a bai::l-:room. For th:LS reason, the body weigh scales are often calleca "bathroom sca:Les." In general, body weigh scales include a platform onto which a user steps, and the user's weight is ttnen displayed. Body weigh scales allow a user to monitor his c::~r her weight, usually before or after a shower, or just after vraking up in the morning.
Many body weigh scales are mer_hanical, spring scales. In a spring scale, a plattorm is connected to a spring, which either stretches or corcupresses to balance a load (i.e., a 1 _ person) placed on the ~:~latform. A needle, whose position depends on the extent t:o which the sp:r:ing is stretched or compressed, indicates i::he weight of the load. Some mechanical scales include a pulse counter and a digital display upon which the user' s weighs::. is shown.
Electronic body wE~i.gh scales utilize electricity to measure loads. Electr<unic. scales are faster, and generally more accurate, than thE::~ir mechanical counterparts. A common type of electronic sca:l.e uses a strain-gauge load cell. This type of scale has a pla:~t:form supported by a column, with a strain gauge or gauges fused to the column. A strain gauge is a thin wire whose elect:ric:a:1 resistance changes when the wire is stretched or compre~-used. When a load is placed on the platform, the column arid strain gauge are compressed. The corresponding change irn resistance of the strain gauge can be used to determine the ~:~erson's weight. The column of the strain-gauge load cell ~r:ust be mounted in a :rigid structure that does not deflect under the load on the body weigh scale.
Otherwise, some of the strain of the object being weighed may be released as strain _.n the structure. By using a rigid structure, the weight <:~f the objf=ct being weighed (e.g., a person) is transferred directly to the strain-gage load cell or cells, so that the <:oiumn may fully compress relative to the rigid structure an~:~ the strain gages in 'the load cell may provide accurate =Lnforrnation about the weight on the body weigh scale.
Although strain-g~~uge load cell scales work well for their intended purpose,. there is a problem with their manufacture. For many c:~ontemporary strain-gauge load cell scales, it is desirable that the upper surface, or load-receiving platform, be decorative, such as a glass top, a faux marble top, a natural ruaterial such a;s stone or marble, or similar decorative sur:f:aces formed from a plastic material.
For glass load-receiving platforms, it has not been possible to form the load-recei~~~ing platform integral with the structure for receivincx the column of the strain-gauge load cell, because glass does not allow much flexibility in shape-forming in its manufact;.ure. Thus, the structure for receiving the column of the stra:i.n-gauge load cell is typically provided in a base that. is separate from the load-receiving platform and that is connected, f:or example by gluing, to the load-receiving platform. Aro. example of a scale having a separate base and load-receivinc:3 platform st=ructure is shown in U.S.
Patent Number 5,955,70'... to Germanton. That patent shows a load-receiving platforrn that fits over a U-shaped frame or base.
Another reason for using the two-piece, load-supporting platform and base construction is that the wires and related circuitry for the stra_i.n gage load sensor are typically sandwiched between the load-supporting structure and the base.
Without the space betwE::en these two mE=tubers, a structure is not available for conta:~i.ning the w~..res.
The use of natural. materials, such as stone, marble, or the like, is expensive on a material basis and a manufacturing basis. Often, t0 aChlE.'.Ve the desired shape, the load-receiving platform must be ground, polished, and/or cut.
After the load-receiving platform is f_orrned, it still has to be attached to a base t=hat includes the strain-gauge load cells, because producing the structure for supporting the strain-gauge i.oad cell: from the natural material would be difficult and expensive.
For load--receivincx platforms that: are made of decorative plastic surfaces, it ha.s r~.ot been pos:~ible to form the structure for receiving the strain-gauge load cell integral with the load-receivinc3 platform, because the plastic materials having the faux finishes are not substantially rigid, and typically, k>e~~ause of shrinkage problems, do not maintain the desired dE~corative f_iruish upon cooling of the parts. Most of the body weigh scales that include plastic materials with a faux f~in-.~sh are compression molded. Because of uneven height shrink: rates in compression molding, to have an ideal decorative su:c°face, most plastic materials must be produced as flat piece,., or otherwise there may be color distortion, surface siruks, visual level changes, or warpage.
For this reason, it is difficult to compression mold a scale in one piece that incl~.zdes a structurE= for receiving the strain-gauge .load cell and that has an attractive decorative surface. If .injection molding or_ die casting is used, the load-receiving platform may experience creepage or age deformation.
Moreover, the pla::;tic material used to create the faux finishes is typically root rigid enough to provide the support for the strain-gauge 1<:>ad cell, un=Less it is provided at very large thicknesses. If t:he strain-gage load cells and related circuitry are mounted l:.nderneath the .Load-receiving platform, the scale must be even taller to receive these structures.
Even if it were possib~.e to fabricate the structure for receiving the strain-gauge load cell integral with the load-receiving platform, thc: resulting strur_ture would have to be extremely thick to have the necessary rigidity for use with strain-gauge load cell:. Recessing the strain-gage load cells in the load-receiving ~l.atform is not practical, because doing so creates thinned are~~.s in the load-receiving platform, which further weakens the loa~.d-receiving pl<~tform (i.e., makes it less rigid), which may result in adverse effects to the finish of the scale. To avoic:~ these problems, as with the scales having glass load-rece:i.ving platforms, the scales using decorative plastic: for the load-receiving platform typically utilize a separate loac-.-receiving plai~form that is mounted over a rigid base that houses the strain-gage load cells and related circuitry.
The two-piecE: con::>t.ruction of a base and a load-receiving platform in contemporary scales results in high costs for assembly. In addition, the resulting scale .is an assembled product that is genera.l.y at least 1 .L/2 inches high, which may be considered largE:~r and more bulky than desired for some uses.
Without the space betwE::en these two mE=tubers, a structure is not available for conta:~i.ning the w~..res.
The use of natural. materials, such as stone, marble, or the like, is expensive on a material basis and a manufacturing basis. Often, t0 aChlE.'.Ve the desired shape, the load-receiving platform must be ground, polished, and/or cut.
After the load-receiving platform is f_orrned, it still has to be attached to a base t=hat includes the strain-gauge load cells, because producing the structure for supporting the strain-gauge i.oad cell: from the natural material would be difficult and expensive.
For load--receivincx platforms that: are made of decorative plastic surfaces, it ha.s r~.ot been pos:~ible to form the structure for receiving the strain-gauge load cell integral with the load-receivinc3 platform, because the plastic materials having the faux finishes are not substantially rigid, and typically, k>e~~ause of shrinkage problems, do not maintain the desired dE~corative f_iruish upon cooling of the parts. Most of the body weigh scales that include plastic materials with a faux f~in-.~sh are compression molded. Because of uneven height shrink: rates in compression molding, to have an ideal decorative su:c°face, most plastic materials must be produced as flat piece,., or otherwise there may be color distortion, surface siruks, visual level changes, or warpage.
For this reason, it is difficult to compression mold a scale in one piece that incl~.zdes a structurE= for receiving the strain-gauge .load cell and that has an attractive decorative surface. If .injection molding or_ die casting is used, the load-receiving platform may experience creepage or age deformation.
Moreover, the pla::;tic material used to create the faux finishes is typically root rigid enough to provide the support for the strain-gauge 1<:>ad cell, un=Less it is provided at very large thicknesses. If t:he strain-gage load cells and related circuitry are mounted l:.nderneath the .Load-receiving platform, the scale must be even taller to receive these structures.
Even if it were possib~.e to fabricate the structure for receiving the strain-gauge load cell integral with the load-receiving platform, thc: resulting strur_ture would have to be extremely thick to have the necessary rigidity for use with strain-gauge load cell:. Recessing the strain-gage load cells in the load-receiving ~l.atform is not practical, because doing so creates thinned are~~.s in the load-receiving platform, which further weakens the loa~.d-receiving pl<~tform (i.e., makes it less rigid), which may result in adverse effects to the finish of the scale. To avoic:~ these problems, as with the scales having glass load-rece:i.ving platforms, the scales using decorative plastic: for the load-receiving platform typically utilize a separate loac-.-receiving plai~form that is mounted over a rigid base that houses the strain-gage load cells and related circuitry.
The two-piecE: con::>t.ruction of a base and a load-receiving platform in contemporary scales results in high costs for assembly. In addition, the resulting scale .is an assembled product that is genera.l.y at least 1 .L/2 inches high, which may be considered largE:~r and more bulky than desired for some uses.
SUM~ARY~OF T8E INVENTION
The present invention is dire:~ted to a body weigh scale that is formed of a polymeric, decorative material that is sufficiently rigid so t::h.at it may be produced relatively thin, and yet not significantly deflect under load. Moreover, the polymeric, decorative rnaterial provides an attractive surface after molding. To this end, the body weigh scale incorporates a fiber-filled, polyes;::er thermosetting polymer material that has extremely low shrinkage rates so that the outer pattern and shape of the scale i.s not affected by the forming of very thin cross sections adjacent to thick cross-sections. This feature permits the sca:~l..es to be formed with integral recesses for housing strain gages. In addition, the fiber-filled, polyester thermosettinc:~ polymer material is sufficiently rigid to permit a body weigh scale to be constructed having a low profile and having a lc:;ad-receiving platform with integrally-formed strain-gauge load cell receptacles. The rigidity of the fiber-filled, poly:est.er thermosetting polymer material provides sufficient structural support for operation of the strain-gauge load cell::c with a thin platform and without significant deflection of the material.
The body weigh scale may be formed from the fiber-filled, polyester thermoset material using a variety of thermosetting polymer formation methc:~ds. As examples, the body weigh scale may be formed using compression, transfer, or stuffer injection molding. Injection molding may be performed using a reverse inverted temperature progress, which involves cold barrel injecting into <:~ hot mold.
By using the fibex:--filled, polyester thermosetting polymer material, therE- is significant= molding flexibility for the load-receiving plai::form of the body weigh scale. For example, ribs may be fc:~rmed integral with the load-receiving platform for receiving the wiring for the strain-gage load cells, without weakening the structure or causing color distortion, surface sinks, visual level changes, or warpage.
In addition, a pocket rr~ay be formed in the top surface of the load-receiving platform for receivAng a digital display, such as a light emitting di<;de (LED) display or a liquid crystal display (LCD).
The strength of the fiber-filled, polyester thermosetting polymer material permits the body weigh scale to have a profile that is thin a:.~ 0.302 inches for a 330 pound scale, and as thin as 0.380 irnches for a 500 pound scale. This allows the body weigh ::~cal.e to be lightweight and easily storable. In addition, the low profile o.f the body weigh scale provides a sleek look that matches many contemporary _ g bathroom designs. Also, because the .f.iber-filled, polyester thermosetting polymer rnat.erial has a .low shrink rate, an aesthetically--pleasing decorative surface may be provided.
Other advantages will become apparent from the following detailed description wluen taken in conjunction with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a perspective view of a body weigh scale incorporating the present invention;
FIG. 2 is a bottom perspective view of the body weigh scale of FIG. 1, showiwc~ an exploded perspective view of one of four strain-gage lo,_ad cells for the body weigh scale;
FIG. 3 is an cutaway view taken along the section lines 3-3 of FIG. 2;
FIG. 4 is a top v:i_ew of an alternate embodiment of a body weigh scale incorporat::..ng the present invention;
FIG. 5 is a sectional view taken along the section lines 5-5 of FIG. 4;
FIG. 6 is a sectional view taken along the section lines 6-6 of FIG. 5;
FIG. 7 is a diagrammatic model of a scale, showing a weight loaded on the sr.°ale; and FIG. $ is a diagrammatic model of a cross-section of the scale of FIG. 7.
DETAILED DESCRIPTION
In the following description, various aspects of the present invention will E:,e described. for purposes of explanation, spec=ific ~:cnfigurations and details are set forth in order to provide a i:.r7orough understanding of the present invention. However, it: will also be apparent to one skilled in the art that the pr~.>.sent invention may be practiced without the specific details. F~'urthermore, we=11-known features may be omitted or simplified i.n order not to obscure the present invention. Tn additioru, too the extent that orientations of the invention are described, such as "top," "bottom," "front,"
"rear," and the like, T=.he orientations are to aid the reader in understanding the irw ention, and a.re not meant to be limiting.
Referring to FIG. 7. of the drawings, there is shown a body weigh scale designated generally by reference numeral 20.
Generally described, the body weigh scale 20 includes a load-receiving platform 22 heaving formed integrally therein receptacles 24 (FIGS. <. and 3). The receptacles 24 are arranged and configurec:~ to receive st=rain-gage load cells 26.
In accordance with the ~>resent invent_i.on, as described further below, the load-receiv-i.r.g platform 22 and the integral receptacles 24 are forrr~ed. of a fiber-.filled, polyester thermosetting polymer material that. has extremely low shrinkage rates so that: color distortion, surface sinks, visual level changes, ~~~r warpage does not occur at the forming of very thin cross sect:i.c>ns adjacent to thick cross-sections, for example, at the jur~ct.ure of the receptacles 24 to adjacent locations of the load-a::eceiving platform 22. In addition, the fiber-filled, polyeste:r:v thermosetting polymer material is sufficiently rigid to l::>ermit a body weigh scale to be constructed having a low profile, such as thin as 0.302 inches thick for a 330 pound ::ca.~~e, or 0.380 inches thick for a 500 pound scale. The rigic:lity of the fiber-filled, polyester thermosetting polymer material provides sufficient structural support for the recept~:cles 24 to allow operation of the strain-gauge :Load cell::: 26 without significant deflection of the load-receiving plat:fcrm 22.
The load---receivinc: platform 22 for the body weigh scale 20 shown in the c:~rawings is substantially square in shape, for example one foot by one foot in dimension. A top surface 30 of the load-w:eceiving platform 22 is flat, but may have a raised surface i.n t:he middle, or indentations to the left and right for recE::iving the feet of a user. In any event, for a scale that; is a body weigh scale, there is typically two location:: on which a usE=r may stand so that the _ 1~> -user's weight may be t:e~ar.sferred to the strain-gage load cells 26, as described further below.
As can be seen in F'IG. 2, a bottom surface 32 of the load-receiving platforru 22 is substantially flat, and includes indentations 34 (one i::> shown best in F°IG. 3) for receiving a top portion of the str<:~in--gage load cells 26. Circular flanges 36 extend upward from the edges of the indentations 34. Althc:>ugln the circular flanges 36 and the indentations 34 are shc,~wn as having circular cross-sections, they may be shaped app:r~opriately (e. g., square or rectangular) for the profile of the strain-gage lo<~d cells that are used.
In addition, if desirec:f, t:he indentations 34 may protrude far enough into the bottom surface 32 of the load-receiving platform 22 that the c:i.rcular flanges 36 are not needed, or the circular flanges 3G may be extended as needed to receive the bulk or all of the strain-gage lo<~d cells 26. As used herein, the structure that: receives the strain-gage load cells 26, whether it i; in the form of an indentation, flanges, some other su~:>pcrting structure that is integral with the load-receiving plat:f:orm 22, or any combination thereof, is called the "receptacle" (e.g., the receptacle 24) for the strain-gage load cells 2 6.
A series of hollo~,n r:~bs 40 ma;~ be provided that extend along the bottom ;~urfac::e 32 of the load-receiving platform 22.
The hollow ribs 40 extfernd between t:he receptacles for the strain-gage load cells 26 (i.e., the :indentations 34 for the strain-gage load cells 26), and to a central juncture 42. The hollow ribs 40 are con:l:'igured and arranged to house wires between the strain-gagE~ load cells 26 and a display 44 (FIG. 1) for the body waE:igh scale 20, as described further below. Wires may also be routed through a channel 48 formed in the bottom surface c:~t the load-receiving platform 22. In the embodiment shown, 2: he hollow ribs 40 extend between adjacent strain-gage lc:~ad cells 26, and from the strain-gage load cells 26 to the central juncture 42. However, as described further below, t:he hollow ribs 40 may extend in any pattern that enables tro.e strain-gage .Load cells 26 and the display 44 to be electo:i.cally connected. A benefit of the structure and arrangement of the hollow ribs 40 shown in FIG. 2, however, is th<:~t. the hollow ribs supply stiffness to the load-receiving platform 22. The ribs 40 add structural strength to the body wc:~i.gh scale 2Ci, permitting it to be produced in thinner cr«ss--section. However, as described below, using the material of the present -invention, a body weigh scale may be produced of th-in cross-sections without supporting structure such as the ribs 40.
A pocket 50 (FIG. 3) is provided in the middle, front portion of the top sur':ace 30 for receiving the display 44.
The pocket 50 shown in fI:G. 3 includes a shoulder 52 for holding the display 44 at. an upper portion of the pocket, and a cavity 54 below the ;shoulder for re~~eiving, for example, wires that lead to the display, or a battery for powering the display, not shown. A,:7 can be seen in FIG. 1, the arrangement and configuration of tLae pocket 40 permits the display 44 to be mounted flush with -;she top surface 30 of the load-receiving platform 22. The pockc~:t 50 may also be formed so that the display 44 is mounted :E~rom the bottom of the load-receiving platform 22. If mounts-.=.d in such a manner, a thin non conductive cover may bc:~ mounted below the display 44 to prevent electrical accf:~ss.
The display 44 mama; be any suitab:Le indicator of the user's weight, for example a digital display, such as a liquid crystal display (hCD) c.~r a light emitting diode (LED) display.
Associated components of the display 44 include the various electronics needed to c:::onvert the sensor signals into a numerical display indic.~ative of weight in a manner known in the art. These components may be mounted in the cavity 54, or in the central juncturE:; 42, for example. If desired, the _ lc~ _ display 44 may be mounted on top of the load-receiving platform 22, without being recessed therein, or may be mounted separate of the load-r<:>.ceiving platform 22. Also, different displays may be used, ~>uch as a dial, or weight may be indicated in another maanner, such as by a recorded voice reading the user's weic:~ht in response tc the user stepping on the scale.
Referring to the ~t~rain-gage load cells 26, their structure and operatior~c forms no part of the present invention and is well known in tlue art. The strain-gage load cells 26 may be, for example, trie load support assemb:Lies in U.S. Pat.
No. 5,955,705 to Germarit:on, assigned tc Measurement Specialties, Inc., and i-ncorporated herein by reference.
Other load cells may a:Lsc be used with the load-receiving platform 22 of the pre::>ent invention, such as piezoresistive, inductive, reluctance, and magnetostr=fictive load cells.
However, for ease of dc-:scription, the invention will be described with referenc:.e to use of the strain-gage load cells 26.
Although the readE::r may refer to the Germanton patent for a description of a str~ci.n--gage load cell, a simplified explanation of the strl:~cture and operation of a strain-gage load cell is generally described here for the reader's - 1F, -convenience. In gener<a.l., a strain gage is a measuring element for converting force, ~>ressure, tension, etc., into an electrical signal. ThE= strain gauges themselves are bonded onto a beam or structural. member that deforms when weight is applied. In many casew, four strain gages are used to obtain maximum sensitivity an<:~ temperature compensation. Two of the gauges are usually in tension, and two in compression, and are wired with compensatiorn adjustments, for example in a Wheatstone bridge. Whfn weight is applied, the strain changes the electrical resistarnce of the gauges in proportion to the load.
In the disclosed c:embodiment, the strain-gage load cells 26 each include a:~ strain gage body 60 (FIG. 2) that houses the strain gage:a, a footpad 62, a boot 64, and a plastic spring element 66. The str_airl gage body 60 seats in one of the indentation:c 39 and is surrounded by the corresponding circular flange 36. The plastic spring element 66 is seated acxainst a plate 68 on the bottom of the strain gage body 60. ~'he plate 68 is attached to the strain gages. The boot 64 is formed of an elastomeric material, and surrounds the plastic :spring element and the footpad 62, which includes a shaft %0 th~:t engages the plastic spring element 66.
In use, the footp~;ds 62 engage the ground, and when an object (e. g., a person) is placed on t:he top of the load-receiving platform 22, the boot 64 compresses against the force applied to the fe:~otpads, and the footpads in turn press (via the shaft 70) the plastic spring element 66 into the plate 66 on the bottom of the strain cage body 60. The strain gages then register thE:~ deformation of. the plate 66 and send signals representing true strain to transducers, which in turn send an electronic sigrual to, for example, a printed circuit board (not shown, but ~;:nown in the art.) attached to the display 44. The printE:~d circuit board or other related circuitry include the various electronics needed to convert the sensor signals intc:~ a numerica7_ display indicative of weight in a manner known in the <~rt.
The signals from t:.he four str_ain--gage load cells 26 are received by the display% 44, or the related circuitry of the display, from wires th~3.t extend through wire tracks in the hollow ribs 40. The wire tracks may be narrow slots (e.g., 1.5 mm / 0.060 inches thick:) that are molded into the bottom of the load-recE::iving platform or connecting ribs that link the strain-gage lc:~aa cells '26. 'The wires are stuffed into these wire tracks and are sealed with a hardening compound (e. g., Room Temperature Vulcanized (or RTV) silicone), or may be ri~tained by a flexible snap-in or push-in material such as polyv:i.nyl chlorids= (:PVC). As can be understood, the wires may be routed in any suitable manner across the bottom surf~:ac:e 32 of the load-receiving platform 22, and f=ewer or more wire tracks may be provided so as to provide routing :f:'or the necessary wiring.
In accordance witl-i the present invention, the load-receiving platform 22 r:.rv~d the receptacles 24 are formed from a fiber-filled, polyester: thermosetting polymer material. The fiber-filled, polyester: thermosetting polymer material is rigid, and has a high rnodulus of e_lasl=icity and high tensile and compressive strength. In addition, the fiber-filled, polyester thermosettin<:~ polymer mater_Lal exhibits a very low shrink rate, which perr;i.ts it to maim:ain its shape after casting, and prevents c:3iscoloration of pigments in the material during the molding process, This combination of features permits the fiber-filled, polyester thermosetting polymer material to not: only provide sufficient rigidity for the use of the strain-cxage load ce1_ls 26, but also to provide an attractive decorative finish that is free of color distortion, surface sir:.ks, visua_L level changes, or warpage.
As one example, tr~.e fiber-filled, polyester thermosetting polymer material may bEBMC 300 Granite provided by Bulk - 1_9 -Molding Compounds, Inc. at 1600 Pow.is Court, West Chicago, Illinois 60185. The BMC: 300 Granite :is a polyester molding material that includes, inter alia, resin, catalysts, powdered mineral filler, reinfor:o:ing fiber (chopped strand), pigment, and lubricants. A var:i.ety of pigments may be provided, which provides flexibility ir°~ surface decoration. BMC 300 Granite has a flexural strength of_ 10 to 23 thousand pounds per square inch, and a flexural mc:~au7_us (modulus of elasticity) of 1.7 to 1.9 million pounds ~:;~er square inch. The flexural strength, provided in part by the; fibers in t=he material, is sufficient to permit manufacture cf the load-receiving platform 22 with narrow and thick portic;ns, for example, the receptacles 24 and adjacent thicker porti<:ms of the load--receiving platform 22.
Because the fiber-filled, polyester thermosetting polymer material is flexurally strong, the th~_nned portions, and the transitions between thEthinned portions and the thicker portions, do not signif:~icantly deflect= when a person is standing on the load-receiving p:lat:form 22. An additional benefit of the BMC 300 Granite is that: it does not support a flame with a 5B rating at only 0.07 inches in thickness.
Other fiber-filled, polyester thermosetting polymer materials may be used, such as are supplied by I=nd~astri_al Dielectrics, Inc. of China.
_ 20 _ The mold shri.nkaga:~ rate for BMC 300 Granite is only 0.001 to 0.003 inches per inc::h. This low shrinkage rate permits the varied thickness load-_eceiving platform 22 to be molded without perceptible co_l.or distortion, surface sinks, or visual level changes. Thus, t;he pattern provided by the pigments in the material is maintained over the surface of the load-receiving platform 22, and the body weigh scale 20 maintains its shape after moldin<:~, providing an aesthetically-pleasing body weigh scale 20. ~:n addition, the molding does not produce significant sti-esses in the final product, which avoids later warpage.
The low shrinkage rates of the fiber-filled, polyester thermosetting polymer nuaterial permits complex surface details to be incorporated intc, the load--receiving platform 22 without affecting the surface ~;attern of the 1_oad-receiving platform.
For example, the hollow ribs 40 and the circular flanges 36 may be molded as part of the load---receiving platform 22, without adversely affecting the decorative pattern on the load-receiving platform 22, or the ave~rall shape of the body weigh scale 20. These details may be added without grinding, polishing, or cutting, s<~ving significant labor costs on the body weigh scale 20. Mot having to perform these machining operations also avoids the associated warpage over time and load.
In accordance witl-~ one aspect of the present invention, the load-receiving pla?:.form 22 is formed via transform (or transfer) molding usin<:x am inverted temperature process, where the heated fiber-filled, polyester thermosetting polymer material is injected v:i.a a cold bar.re:1 into a hot mold.
Alternatively, the loa<:~-receiving platform 22 may be formed by compression molding thE:; fiber-filled, polyester thermosetting polymer material. These processes, along with the low shrinkage rate of the i:iber-filled, polyester thermosetting polymer material, avoid the deformation and creepage associated with the in=jection molding or die casting of most polymeric materials.
FIG. 4 shows an a7_.ternate embodiment of a body weigh scale 120 incorporating the present invention. In the alternate embodiment, a. load-receiving platform 122 for the body weigh scale includes a decorative rib 124 about its perimeter, and a display 144 is mounted from the bottom side of the load-receiving ~;latform 122. The load-receiving platform 122 is substar~tial.ly flat: ti. e., does not include supporting ribs), and load cells 126 (FIG. 5) for the body weigh scale 120 are mounted in small recesses, or receptacles 128 on the bottom corners of the load-receiving platform 122. Wires 1:1,C'~ 1=or the :Load cells 126 are mounted in wire tracks 132 on the bottom of the :load-receiving platform 122. The wide tracks 132 are filled with a hardening material 134, e.g., RTs,% silicon, after the wires 130 are inserted.
The alternate emb<:~diment of the body weigh scale 120 may be produced with a desired finish, such as a faux porcelain finish. In this manne~:v, t:he body weigh scale 120 may match the decorative aspects of a bathroom in which it is placed.
Other decorative surfaces and configurations may be used for the body weigh scale 1a.'0.
Using the fiber-filled, polyester thermosetting polymer material to form the lc:~ad-receiving p7_atform 22 and associated integral parts permits the body weigh scale 20 to be formed having a very low profs.l~V. Referring to FIGS. 7 and 8, the deflection D of the load-receiving platform 22 or 122 is not more than 1/32 inches (0.031 inches) so that the load cells 26 may work properly. That is, so that t:he bulk of the deflection of the scalE~~~ue to a weight W placed on the load-receiving platform 22 is sensed in the load cells 26, not deflected in the load-re~~eiving platform 22.
Knowing the modules of Blast:i.city for the .fiber-filled, polyester thermosetting ~.~olymer mater.i.al, the thickness T may - a.3 -be calculated for particular weights W being square in shape and having a side with a length L, using the following formula:
(0.443) (G°d) (L2) D = ________.__.______ (E) (':C~') With D, W, T, and L defined as above, and E being the modulus of elasticity f:or the load-receiving platform. Using the BMC 300 material, with a modulus of elasticity of 1.8 million psi, and assumi.n~~ a 10 inch square weight, the thickness T for a scaled that is to handle 330 pounds can be determined by solving fo:r T:
(0.443) ;;30 lbs) (10 inches)2 T3 _ ________.._________.____________ _ 0.0262 in3 (180(:)000 psi) (0.031 i.r:ch) Taking the cubic root of 0.0262, 'r is found to be 0.302 inches. A similar calcu:Lation may be performed for a 500 pound weight W, and the result is T - 0.380 inches. For each of these scales, the load-receiving platform does not significantly deflect under load. By 'not significantly - ?_ 4 -deflect," we mean that the bulk of deflection caused by the weight W is absorbed ire the load cells 26, and not in the load-receiving platform. 22. Thus, accurate weight readings may be obtained, even a:~or a person of 500 pounds.
The load cells 26 add to the overall height of the scale, but by recessing the lc:~ad cells :in the receptacles, the height of the scale may be mace shorter. The receptacles, because they are located above or adjacent to the load cells, do not have significant deflection when the load-receiving platform has a weight thereon. Thus, the thic~:ness of the load-receiving platform adjacent to the load cells does not effect the deflection of the l.o~~d-receiving platform.
The decorative finish of the body weigh scale 20 may be selected by the type of- pigment added to the resin mixture.
For example, pigments rr.ay be added to give the load-receiving platform 22 a faux mar~:le finish.
The low profile and decorat=.~ve finishes permitted by the fiber-filled, polyester thermoset~t~ing polymer material allow an attractive body weigh scale 20 to ~>e formed that is easily portable or storable. In addition, because the body weigh scale 20 is thin in profile, a number of the body weigh scales may be shipped in a small container, saving money on shipping.
Moreover, the low shrink rate permits the body weigh scale 20 to be formed in one mo.l.ding step, saving significantly on labor costs.
Other variations pare within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, a certain illustrated embodiment thereof is shown in the drawings and has been described abo~,e in detail. 7.t should be understood, however, that there is no intention to limit the invention to the specific form or fc:~r:ms disclosed, but on the contrary, the intention is to cover a.11 modifications, alternative constructions, and equivalents fal7..ing within the spirit and scope of the invention, ~s defined in the appended claims.
The present invention is dire:~ted to a body weigh scale that is formed of a polymeric, decorative material that is sufficiently rigid so t::h.at it may be produced relatively thin, and yet not significantly deflect under load. Moreover, the polymeric, decorative rnaterial provides an attractive surface after molding. To this end, the body weigh scale incorporates a fiber-filled, polyes;::er thermosetting polymer material that has extremely low shrinkage rates so that the outer pattern and shape of the scale i.s not affected by the forming of very thin cross sections adjacent to thick cross-sections. This feature permits the sca:~l..es to be formed with integral recesses for housing strain gages. In addition, the fiber-filled, polyester thermosettinc:~ polymer material is sufficiently rigid to permit a body weigh scale to be constructed having a low profile and having a lc:;ad-receiving platform with integrally-formed strain-gauge load cell receptacles. The rigidity of the fiber-filled, poly:est.er thermosetting polymer material provides sufficient structural support for operation of the strain-gauge load cell::c with a thin platform and without significant deflection of the material.
The body weigh scale may be formed from the fiber-filled, polyester thermoset material using a variety of thermosetting polymer formation methc:~ds. As examples, the body weigh scale may be formed using compression, transfer, or stuffer injection molding. Injection molding may be performed using a reverse inverted temperature progress, which involves cold barrel injecting into <:~ hot mold.
By using the fibex:--filled, polyester thermosetting polymer material, therE- is significant= molding flexibility for the load-receiving plai::form of the body weigh scale. For example, ribs may be fc:~rmed integral with the load-receiving platform for receiving the wiring for the strain-gage load cells, without weakening the structure or causing color distortion, surface sinks, visual level changes, or warpage.
In addition, a pocket rr~ay be formed in the top surface of the load-receiving platform for receivAng a digital display, such as a light emitting di<;de (LED) display or a liquid crystal display (LCD).
The strength of the fiber-filled, polyester thermosetting polymer material permits the body weigh scale to have a profile that is thin a:.~ 0.302 inches for a 330 pound scale, and as thin as 0.380 irnches for a 500 pound scale. This allows the body weigh ::~cal.e to be lightweight and easily storable. In addition, the low profile o.f the body weigh scale provides a sleek look that matches many contemporary _ g bathroom designs. Also, because the .f.iber-filled, polyester thermosetting polymer rnat.erial has a .low shrink rate, an aesthetically--pleasing decorative surface may be provided.
Other advantages will become apparent from the following detailed description wluen taken in conjunction with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a perspective view of a body weigh scale incorporating the present invention;
FIG. 2 is a bottom perspective view of the body weigh scale of FIG. 1, showiwc~ an exploded perspective view of one of four strain-gage lo,_ad cells for the body weigh scale;
FIG. 3 is an cutaway view taken along the section lines 3-3 of FIG. 2;
FIG. 4 is a top v:i_ew of an alternate embodiment of a body weigh scale incorporat::..ng the present invention;
FIG. 5 is a sectional view taken along the section lines 5-5 of FIG. 4;
FIG. 6 is a sectional view taken along the section lines 6-6 of FIG. 5;
FIG. 7 is a diagrammatic model of a scale, showing a weight loaded on the sr.°ale; and FIG. $ is a diagrammatic model of a cross-section of the scale of FIG. 7.
DETAILED DESCRIPTION
In the following description, various aspects of the present invention will E:,e described. for purposes of explanation, spec=ific ~:cnfigurations and details are set forth in order to provide a i:.r7orough understanding of the present invention. However, it: will also be apparent to one skilled in the art that the pr~.>.sent invention may be practiced without the specific details. F~'urthermore, we=11-known features may be omitted or simplified i.n order not to obscure the present invention. Tn additioru, too the extent that orientations of the invention are described, such as "top," "bottom," "front,"
"rear," and the like, T=.he orientations are to aid the reader in understanding the irw ention, and a.re not meant to be limiting.
Referring to FIG. 7. of the drawings, there is shown a body weigh scale designated generally by reference numeral 20.
Generally described, the body weigh scale 20 includes a load-receiving platform 22 heaving formed integrally therein receptacles 24 (FIGS. <. and 3). The receptacles 24 are arranged and configurec:~ to receive st=rain-gage load cells 26.
In accordance with the ~>resent invent_i.on, as described further below, the load-receiv-i.r.g platform 22 and the integral receptacles 24 are forrr~ed. of a fiber-.filled, polyester thermosetting polymer material that. has extremely low shrinkage rates so that: color distortion, surface sinks, visual level changes, ~~~r warpage does not occur at the forming of very thin cross sect:i.c>ns adjacent to thick cross-sections, for example, at the jur~ct.ure of the receptacles 24 to adjacent locations of the load-a::eceiving platform 22. In addition, the fiber-filled, polyeste:r:v thermosetting polymer material is sufficiently rigid to l::>ermit a body weigh scale to be constructed having a low profile, such as thin as 0.302 inches thick for a 330 pound ::ca.~~e, or 0.380 inches thick for a 500 pound scale. The rigic:lity of the fiber-filled, polyester thermosetting polymer material provides sufficient structural support for the recept~:cles 24 to allow operation of the strain-gauge :Load cell::: 26 without significant deflection of the load-receiving plat:fcrm 22.
The load---receivinc: platform 22 for the body weigh scale 20 shown in the c:~rawings is substantially square in shape, for example one foot by one foot in dimension. A top surface 30 of the load-w:eceiving platform 22 is flat, but may have a raised surface i.n t:he middle, or indentations to the left and right for recE::iving the feet of a user. In any event, for a scale that; is a body weigh scale, there is typically two location:: on which a usE=r may stand so that the _ 1~> -user's weight may be t:e~ar.sferred to the strain-gage load cells 26, as described further below.
As can be seen in F'IG. 2, a bottom surface 32 of the load-receiving platforru 22 is substantially flat, and includes indentations 34 (one i::> shown best in F°IG. 3) for receiving a top portion of the str<:~in--gage load cells 26. Circular flanges 36 extend upward from the edges of the indentations 34. Althc:>ugln the circular flanges 36 and the indentations 34 are shc,~wn as having circular cross-sections, they may be shaped app:r~opriately (e. g., square or rectangular) for the profile of the strain-gage lo<~d cells that are used.
In addition, if desirec:f, t:he indentations 34 may protrude far enough into the bottom surface 32 of the load-receiving platform 22 that the c:i.rcular flanges 36 are not needed, or the circular flanges 3G may be extended as needed to receive the bulk or all of the strain-gage lo<~d cells 26. As used herein, the structure that: receives the strain-gage load cells 26, whether it i; in the form of an indentation, flanges, some other su~:>pcrting structure that is integral with the load-receiving plat:f:orm 22, or any combination thereof, is called the "receptacle" (e.g., the receptacle 24) for the strain-gage load cells 2 6.
A series of hollo~,n r:~bs 40 ma;~ be provided that extend along the bottom ;~urfac::e 32 of the load-receiving platform 22.
The hollow ribs 40 extfernd between t:he receptacles for the strain-gage load cells 26 (i.e., the :indentations 34 for the strain-gage load cells 26), and to a central juncture 42. The hollow ribs 40 are con:l:'igured and arranged to house wires between the strain-gagE~ load cells 26 and a display 44 (FIG. 1) for the body waE:igh scale 20, as described further below. Wires may also be routed through a channel 48 formed in the bottom surface c:~t the load-receiving platform 22. In the embodiment shown, 2: he hollow ribs 40 extend between adjacent strain-gage lc:~ad cells 26, and from the strain-gage load cells 26 to the central juncture 42. However, as described further below, t:he hollow ribs 40 may extend in any pattern that enables tro.e strain-gage .Load cells 26 and the display 44 to be electo:i.cally connected. A benefit of the structure and arrangement of the hollow ribs 40 shown in FIG. 2, however, is th<:~t. the hollow ribs supply stiffness to the load-receiving platform 22. The ribs 40 add structural strength to the body wc:~i.gh scale 2Ci, permitting it to be produced in thinner cr«ss--section. However, as described below, using the material of the present -invention, a body weigh scale may be produced of th-in cross-sections without supporting structure such as the ribs 40.
A pocket 50 (FIG. 3) is provided in the middle, front portion of the top sur':ace 30 for receiving the display 44.
The pocket 50 shown in fI:G. 3 includes a shoulder 52 for holding the display 44 at. an upper portion of the pocket, and a cavity 54 below the ;shoulder for re~~eiving, for example, wires that lead to the display, or a battery for powering the display, not shown. A,:7 can be seen in FIG. 1, the arrangement and configuration of tLae pocket 40 permits the display 44 to be mounted flush with -;she top surface 30 of the load-receiving platform 22. The pockc~:t 50 may also be formed so that the display 44 is mounted :E~rom the bottom of the load-receiving platform 22. If mounts-.=.d in such a manner, a thin non conductive cover may bc:~ mounted below the display 44 to prevent electrical accf:~ss.
The display 44 mama; be any suitab:Le indicator of the user's weight, for example a digital display, such as a liquid crystal display (hCD) c.~r a light emitting diode (LED) display.
Associated components of the display 44 include the various electronics needed to c:::onvert the sensor signals into a numerical display indic.~ative of weight in a manner known in the art. These components may be mounted in the cavity 54, or in the central juncturE:; 42, for example. If desired, the _ lc~ _ display 44 may be mounted on top of the load-receiving platform 22, without being recessed therein, or may be mounted separate of the load-r<:>.ceiving platform 22. Also, different displays may be used, ~>uch as a dial, or weight may be indicated in another maanner, such as by a recorded voice reading the user's weic:~ht in response tc the user stepping on the scale.
Referring to the ~t~rain-gage load cells 26, their structure and operatior~c forms no part of the present invention and is well known in tlue art. The strain-gage load cells 26 may be, for example, trie load support assemb:Lies in U.S. Pat.
No. 5,955,705 to Germarit:on, assigned tc Measurement Specialties, Inc., and i-ncorporated herein by reference.
Other load cells may a:Lsc be used with the load-receiving platform 22 of the pre::>ent invention, such as piezoresistive, inductive, reluctance, and magnetostr=fictive load cells.
However, for ease of dc-:scription, the invention will be described with referenc:.e to use of the strain-gage load cells 26.
Although the readE::r may refer to the Germanton patent for a description of a str~ci.n--gage load cell, a simplified explanation of the strl:~cture and operation of a strain-gage load cell is generally described here for the reader's - 1F, -convenience. In gener<a.l., a strain gage is a measuring element for converting force, ~>ressure, tension, etc., into an electrical signal. ThE= strain gauges themselves are bonded onto a beam or structural. member that deforms when weight is applied. In many casew, four strain gages are used to obtain maximum sensitivity an<:~ temperature compensation. Two of the gauges are usually in tension, and two in compression, and are wired with compensatiorn adjustments, for example in a Wheatstone bridge. Whfn weight is applied, the strain changes the electrical resistarnce of the gauges in proportion to the load.
In the disclosed c:embodiment, the strain-gage load cells 26 each include a:~ strain gage body 60 (FIG. 2) that houses the strain gage:a, a footpad 62, a boot 64, and a plastic spring element 66. The str_airl gage body 60 seats in one of the indentation:c 39 and is surrounded by the corresponding circular flange 36. The plastic spring element 66 is seated acxainst a plate 68 on the bottom of the strain gage body 60. ~'he plate 68 is attached to the strain gages. The boot 64 is formed of an elastomeric material, and surrounds the plastic :spring element and the footpad 62, which includes a shaft %0 th~:t engages the plastic spring element 66.
In use, the footp~;ds 62 engage the ground, and when an object (e. g., a person) is placed on t:he top of the load-receiving platform 22, the boot 64 compresses against the force applied to the fe:~otpads, and the footpads in turn press (via the shaft 70) the plastic spring element 66 into the plate 66 on the bottom of the strain cage body 60. The strain gages then register thE:~ deformation of. the plate 66 and send signals representing true strain to transducers, which in turn send an electronic sigrual to, for example, a printed circuit board (not shown, but ~;:nown in the art.) attached to the display 44. The printE:~d circuit board or other related circuitry include the various electronics needed to convert the sensor signals intc:~ a numerica7_ display indicative of weight in a manner known in the <~rt.
The signals from t:.he four str_ain--gage load cells 26 are received by the display% 44, or the related circuitry of the display, from wires th~3.t extend through wire tracks in the hollow ribs 40. The wire tracks may be narrow slots (e.g., 1.5 mm / 0.060 inches thick:) that are molded into the bottom of the load-recE::iving platform or connecting ribs that link the strain-gage lc:~aa cells '26. 'The wires are stuffed into these wire tracks and are sealed with a hardening compound (e. g., Room Temperature Vulcanized (or RTV) silicone), or may be ri~tained by a flexible snap-in or push-in material such as polyv:i.nyl chlorids= (:PVC). As can be understood, the wires may be routed in any suitable manner across the bottom surf~:ac:e 32 of the load-receiving platform 22, and f=ewer or more wire tracks may be provided so as to provide routing :f:'or the necessary wiring.
In accordance witl-i the present invention, the load-receiving platform 22 r:.rv~d the receptacles 24 are formed from a fiber-filled, polyester: thermosetting polymer material. The fiber-filled, polyester: thermosetting polymer material is rigid, and has a high rnodulus of e_lasl=icity and high tensile and compressive strength. In addition, the fiber-filled, polyester thermosettin<:~ polymer mater_Lal exhibits a very low shrink rate, which perr;i.ts it to maim:ain its shape after casting, and prevents c:3iscoloration of pigments in the material during the molding process, This combination of features permits the fiber-filled, polyester thermosetting polymer material to not: only provide sufficient rigidity for the use of the strain-cxage load ce1_ls 26, but also to provide an attractive decorative finish that is free of color distortion, surface sir:.ks, visua_L level changes, or warpage.
As one example, tr~.e fiber-filled, polyester thermosetting polymer material may bEBMC 300 Granite provided by Bulk - 1_9 -Molding Compounds, Inc. at 1600 Pow.is Court, West Chicago, Illinois 60185. The BMC: 300 Granite :is a polyester molding material that includes, inter alia, resin, catalysts, powdered mineral filler, reinfor:o:ing fiber (chopped strand), pigment, and lubricants. A var:i.ety of pigments may be provided, which provides flexibility ir°~ surface decoration. BMC 300 Granite has a flexural strength of_ 10 to 23 thousand pounds per square inch, and a flexural mc:~au7_us (modulus of elasticity) of 1.7 to 1.9 million pounds ~:;~er square inch. The flexural strength, provided in part by the; fibers in t=he material, is sufficient to permit manufacture cf the load-receiving platform 22 with narrow and thick portic;ns, for example, the receptacles 24 and adjacent thicker porti<:ms of the load--receiving platform 22.
Because the fiber-filled, polyester thermosetting polymer material is flexurally strong, the th~_nned portions, and the transitions between thEthinned portions and the thicker portions, do not signif:~icantly deflect= when a person is standing on the load-receiving p:lat:form 22. An additional benefit of the BMC 300 Granite is that: it does not support a flame with a 5B rating at only 0.07 inches in thickness.
Other fiber-filled, polyester thermosetting polymer materials may be used, such as are supplied by I=nd~astri_al Dielectrics, Inc. of China.
_ 20 _ The mold shri.nkaga:~ rate for BMC 300 Granite is only 0.001 to 0.003 inches per inc::h. This low shrinkage rate permits the varied thickness load-_eceiving platform 22 to be molded without perceptible co_l.or distortion, surface sinks, or visual level changes. Thus, t;he pattern provided by the pigments in the material is maintained over the surface of the load-receiving platform 22, and the body weigh scale 20 maintains its shape after moldin<:~, providing an aesthetically-pleasing body weigh scale 20. ~:n addition, the molding does not produce significant sti-esses in the final product, which avoids later warpage.
The low shrinkage rates of the fiber-filled, polyester thermosetting polymer nuaterial permits complex surface details to be incorporated intc, the load--receiving platform 22 without affecting the surface ~;attern of the 1_oad-receiving platform.
For example, the hollow ribs 40 and the circular flanges 36 may be molded as part of the load---receiving platform 22, without adversely affecting the decorative pattern on the load-receiving platform 22, or the ave~rall shape of the body weigh scale 20. These details may be added without grinding, polishing, or cutting, s<~ving significant labor costs on the body weigh scale 20. Mot having to perform these machining operations also avoids the associated warpage over time and load.
In accordance witl-~ one aspect of the present invention, the load-receiving pla?:.form 22 is formed via transform (or transfer) molding usin<:x am inverted temperature process, where the heated fiber-filled, polyester thermosetting polymer material is injected v:i.a a cold bar.re:1 into a hot mold.
Alternatively, the loa<:~-receiving platform 22 may be formed by compression molding thE:; fiber-filled, polyester thermosetting polymer material. These processes, along with the low shrinkage rate of the i:iber-filled, polyester thermosetting polymer material, avoid the deformation and creepage associated with the in=jection molding or die casting of most polymeric materials.
FIG. 4 shows an a7_.ternate embodiment of a body weigh scale 120 incorporating the present invention. In the alternate embodiment, a. load-receiving platform 122 for the body weigh scale includes a decorative rib 124 about its perimeter, and a display 144 is mounted from the bottom side of the load-receiving ~;latform 122. The load-receiving platform 122 is substar~tial.ly flat: ti. e., does not include supporting ribs), and load cells 126 (FIG. 5) for the body weigh scale 120 are mounted in small recesses, or receptacles 128 on the bottom corners of the load-receiving platform 122. Wires 1:1,C'~ 1=or the :Load cells 126 are mounted in wire tracks 132 on the bottom of the :load-receiving platform 122. The wide tracks 132 are filled with a hardening material 134, e.g., RTs,% silicon, after the wires 130 are inserted.
The alternate emb<:~diment of the body weigh scale 120 may be produced with a desired finish, such as a faux porcelain finish. In this manne~:v, t:he body weigh scale 120 may match the decorative aspects of a bathroom in which it is placed.
Other decorative surfaces and configurations may be used for the body weigh scale 1a.'0.
Using the fiber-filled, polyester thermosetting polymer material to form the lc:~ad-receiving p7_atform 22 and associated integral parts permits the body weigh scale 20 to be formed having a very low profs.l~V. Referring to FIGS. 7 and 8, the deflection D of the load-receiving platform 22 or 122 is not more than 1/32 inches (0.031 inches) so that the load cells 26 may work properly. That is, so that t:he bulk of the deflection of the scalE~~~ue to a weight W placed on the load-receiving platform 22 is sensed in the load cells 26, not deflected in the load-re~~eiving platform 22.
Knowing the modules of Blast:i.city for the .fiber-filled, polyester thermosetting ~.~olymer mater.i.al, the thickness T may - a.3 -be calculated for particular weights W being square in shape and having a side with a length L, using the following formula:
(0.443) (G°d) (L2) D = ________.__.______ (E) (':C~') With D, W, T, and L defined as above, and E being the modulus of elasticity f:or the load-receiving platform. Using the BMC 300 material, with a modulus of elasticity of 1.8 million psi, and assumi.n~~ a 10 inch square weight, the thickness T for a scaled that is to handle 330 pounds can be determined by solving fo:r T:
(0.443) ;;30 lbs) (10 inches)2 T3 _ ________.._________.____________ _ 0.0262 in3 (180(:)000 psi) (0.031 i.r:ch) Taking the cubic root of 0.0262, 'r is found to be 0.302 inches. A similar calcu:Lation may be performed for a 500 pound weight W, and the result is T - 0.380 inches. For each of these scales, the load-receiving platform does not significantly deflect under load. By 'not significantly - ?_ 4 -deflect," we mean that the bulk of deflection caused by the weight W is absorbed ire the load cells 26, and not in the load-receiving platform. 22. Thus, accurate weight readings may be obtained, even a:~or a person of 500 pounds.
The load cells 26 add to the overall height of the scale, but by recessing the lc:~ad cells :in the receptacles, the height of the scale may be mace shorter. The receptacles, because they are located above or adjacent to the load cells, do not have significant deflection when the load-receiving platform has a weight thereon. Thus, the thic~:ness of the load-receiving platform adjacent to the load cells does not effect the deflection of the l.o~~d-receiving platform.
The decorative finish of the body weigh scale 20 may be selected by the type of- pigment added to the resin mixture.
For example, pigments rr.ay be added to give the load-receiving platform 22 a faux mar~:le finish.
The low profile and decorat=.~ve finishes permitted by the fiber-filled, polyester thermoset~t~ing polymer material allow an attractive body weigh scale 20 to ~>e formed that is easily portable or storable. In addition, because the body weigh scale 20 is thin in profile, a number of the body weigh scales may be shipped in a small container, saving money on shipping.
Moreover, the low shrink rate permits the body weigh scale 20 to be formed in one mo.l.ding step, saving significantly on labor costs.
Other variations pare within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, a certain illustrated embodiment thereof is shown in the drawings and has been described abo~,e in detail. 7.t should be understood, however, that there is no intention to limit the invention to the specific form or fc:~r:ms disclosed, but on the contrary, the intention is to cover a.11 modifications, alternative constructions, and equivalents fal7..ing within the spirit and scope of the invention, ~s defined in the appended claims.
Claims (34)
1. A scale, comprising:
a platform having an upper surface for receiving an object, a bottom surface opposite the upper surface, the platform comprising a fiber-filled, polyester thermosetting polymer material;
at least two load cells mounted on the bottom surface for generating data regarding a weight of an object on the platform; and an indicator in communication with the load cell for indicating the weight of the object responsive to the data.
a platform having an upper surface for receiving an object, a bottom surface opposite the upper surface, the platform comprising a fiber-filled, polyester thermosetting polymer material;
at least two load cells mounted on the bottom surface for generating data regarding a weight of an object on the platform; and an indicator in communication with the load cell for indicating the weight of the object responsive to the data.
2. The scale of claim 1, wherein the indicator comprises a display for displaying the weight.
3. The scale of claim 2, wherein the display comprises a digital display.
4. The scale of claim 2, wherein the display is mounted in a pocket in the upper surface of the platform.
5. The scale of claim 1, wherein the platform comprises at least two receptacles on the bottom surface, and wherein one each of the at least two load cells is mounted in one of the at least two receptacles.
6. The scale of claim 5, wherein each of the receptacles comprises an indentation in the bottom of the platform.
7. The scale of claim 6, wherein the at least two load cells are connected to the indicator, and wherein the indicator generates the weight of the object responsive to the data from the four load cells.
8. The scale of claim 7, further comprising structures formed integrally with the platform and for receiving wires that extend between the at least two load cells and the indicator.
9. The scale of claim 8, wherein the structures each comprise ribs that extend along the bottom surface of the platform.
10. The scale of claim 7, wherein the platform comprises sufficient flexural strength to not significantly deflect under a load of 500 pounds.
11. The scale of claim 10, wherein the scale has a height approximately equal to 0.380 inches.
12. The scale of claim 7, wherein the scale comprises sufficient flexural strength to not significantly deflect under a load of 330 pounds.
13. The scale of claim 12, wherein the scale has a height approximately equal to 0.302 inches.
14. The scale of claim 7, wherein the indicator comprises a display for displaying the weight.
15. The scale of claim 14, wherein the display comprises a digital display.
16. The scale of claim 14, wherein the display is mounted in a pocket in the upper surface of the platform.
17. The scale of claim 7, wherein the at least two load cells each comprise a strain-gage load cell.
18. The scale of claim 5, wherein the at least two load cells are in communication with the indicator, and wherein the indicator generates the weight of the object responsive to the data from the at least two load cells.
19. The scale of claim 18, further comprising structures formed integrally with the platform and for receiving wires that extend between the at least two load cells and the indicator.
20. The scale of claim 19, wherein the structures each comprise ribs that extend along the bottom surface of the platform.
21. The scale of claim 18, wherein the scale comprises sufficient flexural strength to not significantly deflect under a load of 500 pounds.
22. The scale of claim 21, wherein the scale has a height approximately equal to 0.380 inches.
23. The scale of claim 18, wherein the scale comprises sufficient flexural strength to not significantly deflect under a load of 330 pounds.
24. The scale of claim 23, wherein the scale has a height approximately equal to 0.302 inches.
25. The scale of claim 18, wherein the indicator comprises a display for displaying the weight.
26. The scale of claim 25, wherein the display comprises a digital display.
27. The scale of claim 25, wherein the display is mounted in a pocket in the upper surface of the platform.
28. The scale of claim 1, wherein the at least two load cells each comprise a strain-gage load cell.
29. The scale of claim 1, wherein the scale comprises sufficient flexural strength to not significantly deflect under a load of 500 pounds.
30. The scale of claim 29, wherein the scale has a height approximately equal to 0.380 inches.
31. The scale of claim 1, wherein the scale comprises sufficient flexural strength to not significantly deflect under a load of 330 pounds.
32. The scale of claim 31, wherein the scale has a height approximately equal to 0.302 inches.
33. The scale of claim 1, further comprising a structure formed integrally with the platform and for receiving at least one wire that extends between one of the at least two load cells and the indicator.
34. The scale of claim 33, wherein the structure comprises at least one rib that extends along the bottom surface of the platform.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10/008,346 US6797894B2 (en) | 2001-11-09 | 2001-11-09 | Weigh scale having unitary platform and load cell structures |
| US10/008,346 | 2001-11-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2411634A1 true CA2411634A1 (en) | 2003-05-09 |
Family
ID=21731098
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002411634A Abandoned CA2411634A1 (en) | 2001-11-09 | 2002-11-08 | Weigh scale having unitary platform and load cell structures |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US6797894B2 (en) |
| CA (1) | CA2411634A1 (en) |
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Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4177868A (en) | 1978-01-30 | 1979-12-11 | Bio-Dynamics Inc. | Weight-measuring and display device |
| US4355692A (en) | 1980-11-24 | 1982-10-26 | General Electric Company | Thick film resistor force transducers and weighing scales |
| US4433741A (en) | 1982-04-12 | 1984-02-28 | General Electric Company | Strain gage scale |
| US4487276A (en) * | 1983-05-03 | 1984-12-11 | Swersey Burt L | Scale of flat construction |
| WO1985004711A1 (en) | 1984-04-13 | 1985-10-24 | Esselte Meto International Gmbh | Scales |
| US4819750A (en) | 1988-02-16 | 1989-04-11 | Sunbeam Corporation | Electronic bath scale |
| US4800973A (en) | 1988-03-04 | 1989-01-31 | Shlomo Angel | Portable electronic scale of minimal thickness and weight |
| US4979581A (en) | 1988-05-27 | 1990-12-25 | Kroll William P | Low profile wheel scale assembly |
| US4993506A (en) | 1989-12-11 | 1991-02-19 | Shlomo Angel | Mass-produced flat one-piece load cell and scales incorporating it |
| US5886302A (en) * | 1995-02-08 | 1999-03-23 | Measurement Specialties, Inc. | Electrical weighing scale |
| US5955705A (en) | 1997-01-28 | 1999-09-21 | Measurement Specialties, Inc. | Modular weighing scale |
| US5894112A (en) * | 1997-06-26 | 1999-04-13 | Intercomp Company | Weighing scale apparatus |
| DE19833767C2 (en) * | 1998-07-17 | 2000-07-27 | Francotyp Postalia Gmbh | Device for weighing moving mail |
| GB9926535D0 (en) * | 1999-11-09 | 2000-01-12 | Terraillon Holdings Ltd | A weighing scale |
-
2001
- 2001-11-09 US US10/008,346 patent/US6797894B2/en not_active Expired - Lifetime
-
2002
- 2002-11-08 CA CA002411634A patent/CA2411634A1/en not_active Abandoned
Cited By (3)
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|---|---|---|---|---|
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Also Published As
| Publication number | Publication date |
|---|---|
| US6797894B2 (en) | 2004-09-28 |
| US20030089531A1 (en) | 2003-05-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |