United States Patent [19;
`Swanepoel
`
`[54] WINDSCREEN WIPER BLADE WITH
`CURVED BACKING MEMBER
`[76] Inventor: Adriaan R. Swanepoel, 309 Aries
`Street, Waterkloof Ridge, Pretoria,
`Transvaal Province, South Africa
`[21] Appl. No.: 167,615
`[22] Filed:
`Dec. 15, 1993
`
`[63]
`
`Related US. Application Data
`Continuation of Ser. No. 928,981, Aug. 12, 1992, aban
`doned.
`Foreign Application Priority Data
`[30]
`Aug. 16, 1991 [ZA] _ South Africa ..................... .. 91/6473
`Jan. 17, 1992 [ZA] South Africa ..................... .. 92/0354
`
`[51] Int. Cl.5 .............................................. .. B605 1/38
`[52] US Cl. ............................. .. 15/250.42; 15/25036
`[58] Field of Search ......... .. 15/25042, 250.36, 250.20,
`15/250.002, 250.41, 250.40, 250.37, 250.38,
`250.39, 250.001; D12/155
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`2,589,339 3/1952 Carson ........................... .. l5/250.36
`3,029,460 4/1962 Hoyler
`15/250.42
`3,104,412 9/1963 Hinder
`l5/250.42
`3,192,551 7/1965 Appel
`15/250.42
`3,480,986 12/1969 Forster ........ ..
`15/250.36
`3,751,754 8/1973 Quinlan et a1.
`15/250.42
`3,780,375 12/1973 Quinlan et a1.
`15/250.42
`3,872,537 3/1975 Bionchi ....... ..
`15/250.36
`3,881,214 5/1975 Palu ..... ..
`l5/250.42
`4,028,770 6/1977 Appel
`15/2so.42
`4,063,328 12/1977 Arman ............................ .. l5/250.42
`
`lllllllllllllllllllllllllllIllllllllllllllIllllllllllllllllllllllllllllllll
`
`USOO5325564A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,325,564
`Jul. 5, 1994
`
`4,102,003 7/1978 Hancu ............................ ..15/2s0.42
`4,127,916 12/1978 van den Berg et a1.
`.. 15/250 42
`4,339,839 7/1982 Knights ................. ..
`15/ 250.42
`4,343,063 8/1982 Batt ........ ..
`.. 15/250.42
`4,587,686 5/1986 Thompson ..
`4,807,326 2/1989 Arai et a1. ...................... .. 15/250.42
`
`FOREIGN PATENT DOCUMENTS
`2311293 9/1974 Fed. Rep. of Germany
`l5/250.42
`2336271 2/ 1975 Fed. Rep. of Germany
`15/25042
`2350302 4/1975 Fed. Rep. of Germany
`15/250.42
`2353368 5/ 1975 Fed. Rep. of Germany
`l5/250.42
`2515121 4/1983 France .
`1012902 5/ 1963 United Kingdom .
`1395918 5/1975 United Kingdom ........... .. 15/250.42
`Primary Examiner-Timothy F. Simone
`Assistant Examiner—-Gary K. Graham
`Attorney, Agent, or Firm-Cushman, Darby & Cushman
`[57]
`ABSTRACT
`A curved elongate backbone for a windscreen wiper
`has a loading pro?le that increases substantially from a
`central connector towards one or both ends of the back
`bone. The second differential of the bending moment
`also increases substantially from the connector towards
`the ends. The loading may increase right to the ends of
`the backbone or the backbone may have end portions
`with constant loading. In order to obtain the desired
`loading pro?le the width, thickness and free-form ra
`dius of curvature are suitably selected. In preferred
`embodiments, the backbone has a rectangular cross-sec
`tional profile and the thickness and width decrease
`uniformly from the connector to the ends. However the
`thickness may also be constant for end portions.
`
`16 Claims, 3 Drawing Sheets
`
`Costco Exhibit 1005, p. 1
`
`

`
`US. Patent
`
`July 5, 1994
`
`Sheet 1 of 3
`
`5,325,564
`
`FIG 2
`
`l2
`
`FIG 3
`
`Costco Exhibit 1005, p. 2
`
`

`
`US. Patent
`
`July 5, 1994
`
`Sheet 2 0f 3
`
`5,325,564
`
`=5 5:253 “6 955.
`
`L. .h. ... 0
`
`05 0-4 0-3 0-2 O-l
`0
`DISTANCE FROM WIPER TIP (111)
`FIG 5
`
`2-5
`
`RADIUS OF _
`c
`T
`20 URVA URE(m)
`
`l5
`
`IO
`
`ca
`
`-2'o
`
`DISTANCE FROM CENTRE (Cm)
`FIG 6
`
`Costco Exhibit 1005, p. 3
`
`

`
`US. Patent
`
`July 5, 1994
`
`Sheet 3 of 3
`
`5,325,564
`
`26
`
`20'
`
`RADIUS OF
`CURVATUR E (m)
`
`-2b
`
`45
`
`f0
`5
`o
`-E'>
`-|o
`DISTANCE FROM CENTRE (cm)
`FIG 7
`
`:5
`
`2b
`
`2'5
`
`RADIUS OF
`CURVATURE (m)
`
`lb
`3
`-5
`i6 4? I-fo
`DISTANCE FROM CONNECTOR (cm)
`FIG 8
`
`I5 20*
`
`Costco Exhibit 1005, p. 4
`
`

`
`1
`
`WINDSCREEN WIPER BLADE WITH CURVED
`BACKING MEMBER
`
`This is a continuation of application Ser. No.
`07/928,981, ?led on Aug. 12, 1992, which was aban
`doned upon the ?ling hereof.
`
`5
`
`BACKGROUND OF THE INVENTION
`This invention relates to a windscreen wiper and
`more particularly to an elongate curved backbone for a
`windscreen wiper which is of a suitably resiliently flexi
`ble material.
`
`5,325,564
`2
`the backbone. Further, the force per unit length may
`increase towards both ends in a similar or dissimilar
`manner. Similarly, the second differential of M(x) may
`increase substantially from the connecting formation
`towards only one end or towards both ends. If it in
`creases towards both ends this may be in a substantially
`similar or dissimilar manner.
`The force per unit length and the second differential
`of M(x) may increase progressively towards the ends of
`the backbone until a short distance from each end and
`the backbone may then have two small portions at each
`end where the force per unit length and the second
`differential are a constant value. Further, the backbone
`may be such that in these small portions the force per
`unit length and the second differential are constant right
`to the tips of the backbone, or, at tip regions the back
`bone may be such that the force per unit length and the
`second differential decrease from the constant value to
`zero at the extremities of the backbone.
`The force per unit length may increase, at least in the
`central region of the backbone, in an exponential man
`ner. Conveniently,
`
`20
`
`SUMMARY OF THE INVENTION
`According to the invention there is provided a wind
`screen wiper which includes an elongate curved back
`bone which is of a resiliently ?exible material and which
`has a connecting formation at a position intermediate its
`length for connection to a displacing and force applying
`member, the backbone having a suitably varying trans
`verse cross-sectional pro?le along its length and a suit
`able free-form curvature for the backbone to achieve,
`when it is pressed downwardly at the connecting for
`mation onto a flat surface by a force suf?cient to
`straighten the backbone, a force per unit length exerted
`perpendicularly to the surface which increases substan
`tially from the position of the connecting formation
`towards at least one end of the backbone.
`The backbone may be curved in a plane- the plane of
`curvature.
`Further according to the invention there is provided
`a windscreen wiper which includes an elongate back
`bone which is curved in a plane, which is of a resiliently
`?exible material and which has a connecting formation
`at a position intermediate its length for connection to a
`displacing and force applying member, the backbone
`having a suitably varying cross-sectional pro?le along
`its length and a suitable free-form curvature, such that
`the second differential of the function M(x) increases
`substantially from the said position towards at least one
`end of the backbone, where
`
`30
`
`35
`
`where
`f(x)=force per unit length at a distance x from the
`connecting formation,
`A and C are determinable constants, and
`n is greater than unity.
`Conveniently, n may be at least 3, is least 6 and is
`preferably about 10.
`Those skilled in the art will appreciate that I (x) is
`determined by the transverse dimensions of the back
`bone at any position along its length. In most cases, the
`backbone will have a regular cross-sectional pro?le
`which may, for example be rectangular or ellipsoidal.
`Thus, in most instances, the backbone will have a width
`and a thickness. It will be understood that the width
`dimension will be that dimension which extends perpen
`dicularly to the plane of curvature and the thickness
`will be the dimension which lies in the plane of curva
`ture.
`The thickness of the backbone may decrease from the
`connecting formation towards both ends until a prede
`termined distance from the ends, with the thickness
`being constant along these end portions. These end
`portions may have a length of at least 20 mm.
`It can be shown, that with a backbone which has a
`rectilinear cross-section at all positions along its length,
`that
`
`E ' b, - 11,3
`M(x) = W
`
`where
`b, equals the width at distance x,
`hx equals thickness at distance it.
`Thus, with a backbone having a rectangular cross
`section, the width and thickness may vary in a predeter
`mined manner and the radius of curvature may then be
`varied so that M(x), and mrs second differential vary in
`the desired manner.
`If the backbone has an elliptical cross-section then it
`can be shown that
`
`65
`
`M(x) =
`
`with
`E=modulus of elasticity
`I(x)=cross-section moment of inertia of the backbone
`about a neutral axis transverse to the plane of cur
`vature, at a distance x from the said position; and
`R(x)=free-form radius of curvature of the backbone
`in the plane of curvature at x.
`The wiper may include a wiper blade attached to the
`backbone and the sufficient force referred to above may
`be that force which causes the blade to contact the
`surface in a straight operative manner.
`Persons skilled in the art will appreciate that the
`backbone will have a concave side and a convex side,
`the wider blade being attached to the concave side and
`the displacing and force applying member on the con
`vex side.
`The backbone may conveniently be of a metal such as
`spring steel and may be in the form of a single strip or
`may be in the form of a laminate.
`The connecting formation may be centrally located
`or the wiper may be assymetric. The force per unit
`length may increase towards only one end of the back
`bone, but preferably it increases towards both ends of
`
`Costco Exhibit 1005, p. 5
`
`

`
`M0‘) =
`
`1r ' E ' bx ' 11,3
`64 n Rx
`
`5,325,564
`4
`the windscreen wiper of FIGS. 1 to 3 when it is pressed
`against a ?at surface in an operational manner;
`FIG. 5 illustrates the curvature requirement to which
`a wiper blade should conform to operate satisfactorily
`5 on a typically curved motor vehicle windscreen;
`FIG. 6 shows graphically the variation in the radius
`of curvature of the wiper of FIGS. 1 and 2 in its free
`form condition;
`FIG. 7 shows graphically the variation in the radius
`of curvature of a further embodiment of a wiper which
`has a symmetrical backbone with tip portions of con
`stant thickness; and
`FIG. 8 shows graphically the variation in the radius
`of curvature of a still further embodiment of a wiper
`which has an assymetric backbone with tip portions of
`constant thickness.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`The invention is now described by way of example
`only with reference to the drawings.
`The windscreen wiper of the invention is shown in
`FIGS. 1 to 3 to include a spring backbone 10 and a
`wiper blade 12. The backbone 10 has a centrally located
`connector 14 for releasably connecting the wiper to a
`spring loaded wiper arm (not shown). The connector 14
`could be of any suitable type. The backbone 10 has
`suitable attachment formations (also not shown) to en
`sure that the blade 72 is securely attached to the back
`bone 10.
`The spring backbone of the wiper is preferably made
`from spring steel and tapers both in width and thickness
`from its centre towards its free ends or tips. The back
`bone is pre-curved longitudinally with a predetermined
`radius of curvature at every point in its length. The
`backbone 10 de?nes a plane, which is de?ned by the
`sheet of paper in FIG. 2. The cross section of the back
`bone is preferably rectangular but may be of any other
`suitable shape. Most importantly to the invention the
`thickness and width of the backbone 10 and its radius of
`curvature are matched at every point along the length
`of the backbone so that the backbone will provide a
`force per unit length distribution in a longitudinal direc
`tion which increases towards both tips of the wind
`screen wiper when the windscreen wiper is, in use,
`pressed downward intermediate its ends onto a flat
`surface, as shown in FIG. 1, by a force F which is equal
`in magnitude to the down force required to straighten
`the backbone. By straighten is meant that the force F
`must be adequate to render the wiper blade 12 fully
`functional.
`A suitable force per unit length distribution is shown
`in FIG. 4, where the various parameters have the fol
`lowing meaning:
`F=downforce applied to wiper by wiper arm.
`f(x)=force per unit length distribution between
`
`B=Maximum loading acceptable at tips, in N/m.
`XLMAX=point where maximum loading starts.
`DXLMAX= distance from tip for which the maximum
`loading B applies
`L=length of wiper blade.
`In this example, the following values are assumed
`
`L=0.45 m
`.
`DXLMAX=QO2 m, therefor XLMAX=0,205 m
`
`If the backbone has any other cross-sectional pro?le
`the equation for M(x) may be determined utilising con
`ventional mathematical techniques.
`Those skilled in the art will appreciate that there is a
`relationship between the second differential of M(x) and 10
`the force per unit length. Thus, the second differential
`of M(x) may vary in the same manner as that described
`above for the force per unit length.
`It will be appreciated further that the width, thick
`ness and radius of curvature also determine other char
`acteristics of the backbone. Thus, the radius of curva
`ture of the backbone will determine the extent of curva
`ture of a windscreen that can be cleaned by the wiper.
`Thus, if the windscreen, in any particular region, has a
`greater curvature than that portion of the wiper that is
`to pass thereover, then the wiper will not clean that
`region of the windscreen in an effective manner.
`Similarly, the width and thickness will determine the
`rigidity of the wiper and if the backbone is too thin at its
`tips it will be vulnerable to mechanical damage.
`Those skilled in the art will also appreciate that M(x)
`is the bending moment of the backbone.
`Further, if a curved beam is uniformly loaded, i.e. the
`force per unit length is a constant along the length of
`the beam when it is pressed down onto a flat surface,
`then the bending moment is
`
`30
`
`Mxx) =
`
`where
`F=the total force applied to the beam to straighten it
`against a ?at surface, and
`L=the length of the beam.
`Thus, with a rectangular backbone if
`
`35
`
`b, ' 11,3
`
`at all positions along at least a part of the backbone
`(which is a substantial part), then the backbone will be
`such that the force per unit length increases along the
`length of this part of the backbone away from the con
`necting formation.
`Similarly, with an elliptical cross-section, the back
`bone will have an increasing force per unit length if
`
`b, ' 11,9
`
`55
`
`For practical reasons, the backbone should have end
`with a constant radius of curvature, and the tips them
`selves are preferably straight.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a perspective view from above of the wind
`screen wiper of the invention with the drawing being
`shortened for clarity of illustration;
`FIG. 2 is a side elevation of the FIG. 1 windscreen
`wiper shown in an unloaded free form condition;
`FIG. 3 is an end elevation of the wiper;
`FIG. 4 is a force distribution diagram illustrating the
`lengthwise distribution of the force per unit length on
`
`65
`
`Costco Exhibit 1005, p. 6
`
`

`
`5,325,564
`6
`5
`It will be appreciated that the distribution between
`bone when pressed onto a ?at surface, as illustrated in
`FIG. 4, must increase towards the tips of the backbone
`—XLMAX and +XLMAX is of the form
`'
`as shown in the drawing.
`The curvature required to give this loading pro?le is
`determined in the following way.
`Using equation (1) above, the parameter C in FIG. 4
`is calculated iteratively until f(x)=B at the point
`
`?x)=Alxl"~+-C
`
`(1)
`
`where n= 10.
`The co-ef?cient A in equation (1) is determined from
`the formula
`
`A _ (n + 1)[F — ZCXLMAX — 2B DXLMAXl
`
`(1)
`
`_
`
`wiltiax
`
`Equation (2) represents a situation where the force
`distribution balances the total force F. As indicated in
`the broad description above, the distribution at the ends
`of the backbone is a constant (B). Further, as indicated
`above, the loading may decrease right at the tips, al
`though this is not shown in FIG. 4.
`To achieve the increasing loading (as discussed
`above) the thickness of the spring backbone at any posi
`tion in its length must subscribe to the following equa
`tion:
`
`In this example, C: 11.63 N/m.
`With C known, A can now be determined from equa
`tion (2). The value of A is approximately 171,300,000
`N/mll.
`From basic Strengths of Material theory, the bending
`moment equation where L/2> Ixi >XLMAX is
`
`S
`
`By derivation from Standard Strengths of Material
`theory, the bending moment equation where X<XL
`MAX is
`
`h(x) > [
`
`ZLEbx
`
`1!
`
`25
`
`The above equation relates to a wiper backbone
`which has a substantially rectangular cross sectional
`shape. In further experimentation with the wiper back
`bone of the invention it may, however, as mentioned
`above, be found that cross sectional shades other than
`rectangular may provide the backbone with better
`structural characteristics than does the rectangular
`backbone. In this event, the equation will need to be
`adapted to suit the particular shape required. For exam
`ple, in a backbone having an elliptical cross section the
`equation will need to be adjusted as follows:
`
`h(x) > I:
`
`BRXFWZ - 41.x + L2)
`11 LEbx
`
`i
`
`1
`
`Ayn+l
`11 +1
`
`Ayn+2
`n + 2
`
`where Y=XLMAX
`At any point x along the length of the backbone, the
`radius of curvature R is given by
`
`The wiper blade 12 is made from a suitable rubber or
`elastomeric material and in the currently preferred em
`bodiment of the invention is shaped in cross section as
`illustrated in FIG. 3. The cross sectional shape of the
`blade 12 may, however, if required, be made variable at
`various positions in its length.
`
`EXAMPLE 1
`A wiper backbone, which is of spring steel and has a
`rectangular cross-sectional pro?le and which has the
`required loading increase towards its tips, torsional
`rigidity and wrap around capability has the following
`dimensional values:
`
`modulus of elasticity
`length
`thickness at the centre of the backbone
`thickness at the tips
`width at the centre
`width at the tips
`
`207 x 109 N/mz
`450 mm
`1.29 mm
`0.22 mm
`l] mm
`6 mm
`
`I(x)=cross section moment of inertia at position x,
`E=modulus of elasticity (Y oung’s modulus)
`M(x)=is given by either equation (3) or (4), depend
`ing on the value of x.
`Using equation (5) the radius of curvature as shown in
`FIG. 6 is determined.
`At all points it (except for the last 45 mm at the tips)
`the example backbone satisfies the curvature require
`ments represented by FIG. 5, i.e. R(x) according to
`equation (5) is smaller than the required radius of curva
`ture.
`
`EXAMPLE 2
`The example described above is of a wiper having a
`rectangular backbone which tapers uniformly in both
`thickness and width in a straight line manner from its
`centre to its tips. As indicated above, the backbone
`could have tip portions of constant thickness. The di
`mensions and other values for such a backbone in accor
`dance with the invention are
`
`The backbone tapers uniformly in both thickness and
`width in a straight line manner from its centre to its tips.
`As has been mentioned above it is essential to this
`invention that the reactive loading on the wiper back
`
`F =
`L =
`DXLMAX =
`
`6,3 N
`44 cms
`3
`
`

`
`7
`-continued
`
`5,325,564
`
`8
`-continued
`
`13 =
`n =
`modulus of elasticity =
`length =
`thickness at the centre of the =
`baFkbmle
`v
`_
`?l‘ckness 3‘ the "pp‘mwns .=
`distance from the tips for which =
`thickness remains comm,
`width at centre =
`Width at the tips =
`
`20 N/m
`10
`207 x 109 N/mz
`440 mm
`1.15 mm
`
`0'43 mm
`45 mm
`
`11 mm
`6mm
`
`Thus, the backbone tapers uniformly in width from
`its centre to its tips and uniformly in thickness from its
`centre to 175 mm from the centre, then the thickness
`remains constant for the next 45 mm right to the tips.
`These parameters produce the following results
`C= 12.85 N/m
`A= 102,000,000 N/m11 (approximately).
`Using these values in equations (3), (4) and (5) above,
`the following radius of curvature are obtained
`
`X (cm)
`
`Radius of Curvature (m)
`0,766
`0,704
`0,643
`0,586
`0,535
`0,490
`0,454
`0,430
`0,433
`0,568
`2
`826
`
`Width at connector =
`width at the tips =
`
`11 mm
`6 mm.
`
`_
`_
`Thus the shorter side of the backbone has a width that
`decreases uniformly to the tip and a thickness that de
`creases uniformly for a distance of 167 mm from the
`.
`.
`connector and which then remains constant for the
`10 remaining 45 mm right to the tip.
`These parameters produce the following results for
`the short side of the blade
`
`A=236,000,000 N/ml1 (approximately).
`Using these above values in equations (3), (4) and (5)
`above, the following radii of curvature result
`
`X (cm)
`
`Radius of Curvature (m)
`0,778
`0,709
`0,641
`0,579
`0,522
`0,472
`0,433
`0,408
`0,416
`0,777
`4,657.
`Dealing now with the longer side of the backbone
`
`The total force applied to the longer side of the back
`bone is 3,1N, therefore for a notional symmetric back
`bone
`
`20
`
`25
`
`30
`
`35
`
`The radius of curvature of such a wiper is shown
`graphically in FIG. 7.
`
`The length of the longer side is 238 mm therefore for
`a notional symmetric backbone
`
`EXAMPLE 3
`Further, as indicated above a rectangular backbone
`could be assymmetric, having a connector that is not
`centrally located, and the loading is different towards
`both ends. The dimensions of, and other values for, such
`a backbone in accordance with the invention are
`
`45
`
`L=45 cms.
`The connection point is shifted 13 mm longitudinally
`from the geometric centre, to one side of the backbone.
`The shorter side of the backbone is therefore 212 mm
`50
`long and the longer side is 238 mm long.
`Dealing firstly with the shorter side. The total force
`applied to the shorter side of the beam is 3.2N, therefore
`for a notional symmetric backbone
`
`The length of the shorter side is 212 mm, therefore for
`a notional symmetric backbone
`
`L=
`DXLMAX =
`XLMAX =
`=
`n =
`modulus of elasticity =
`thickness at connector =
`thickness at tips =
`distance from the tips for which =
`thickness remains the same
`
`2'21Zmm=424mm
`3 cms, therefore
`18.2 crns
`22 N/rn
`10
`207 ' 109 N/m2
`1.15 mm
`0.43 mm
`45 mm
`
`55
`
`60
`
`65
`
`L=
`D XLMAX =
`XLMAX =
`=
`1'1 =
`thickness at connector =
`thickness at tips =
`distance from the tips for which =
`thickness remains the same
`width at connector =
`width at the tips =
`
`2‘238mm=476mm
`0, therefore
`238 mm
`13.1 N/m
`10
`1.15 mm
`0.40 mm
`45 mm
`
`11 mm
`6 mm.
`
`Thus the longer side of the backbone has a width that
`decreases uniformly to the tip and a thickness that de
`creases uniformly from the connector for a distance of
`193 mm and then remains constant for the next 45 mm
`right to the tip.
`With this example, the longer side has uniform load
`ing and thus, these parameters produce, for the longer
`side,
`C: 13.1 N/m
`A=0 N/ml 1; and
`Using the above values, as before, the following radii
`of curvature are obtained.
`
`X (cm)
`0
`2
`4
`6
`
`Radius of Curvature (m)
`0,779
`0,727
`0,675
`0,627
`
`Costco Exhibit 1005, p. 8
`
`

`
`X (cm)
`
`9
`-continued
`Radius of Curvature (m)
`0,584
`0,546
`0,515
`0,493
`0,488
`0,515
`0,757
`2.993v
`
`5,325,564
`10
`the backbone being curved in a plane, and the back
`bone having a cross-sectional pro?le and a free
`form curvature which vary along its length, and
`wherein the second differential of the function
`M(x) increases along said first portion towards said
`?rst longitudinal end, where
`
`E ‘I x
`M(x) = Tug-)
`
`The radius of curvature of such a wiper is shown
`graphically in FIG. 8.
`It will be noted that, with the ?rst two examples,
`between —XLMAXand XLMAX, the force per unit length
`exerted perpendicularly when the backbone is straight
`ened increases substantially from the middle towards
`the ends; the second differential of M(x) also increases
`substantially; and
`
`15
`
`20
`
`b, ' 11,3
`
`30
`
`35
`
`45
`
`with ’E=the modulus of elasticity of the backbone;
`I(x)=the cross-section moment of inertia of the
`backbone about a neutral axis at a distance x
`from said position transverse to the plane of
`curvature; and
`R(x)=the free-form radius of curvature of the
`backbone in the plane of curvature at x.
`2. A windscreen wiper as in claim 1, wherein the
`connections formation is provided and said thickness is
`greatest, midway between the ends of said backbone.
`3. A windscreen wiper as in claim 1, wherein at least
`one of the thickness and the width of the backbone also
`gradually decrease along said backbone from said posi
`tion to said second longitudinal end.
`4. A windscreen wiper as in claim 1, wherein the
`width of the backbone is greatest at said position and the
`width of said backbone gradually decreases along at
`least said ?rst portion of said backbone.
`5. A windscreen wiper assembly comprising:
`an elongated wiper blade having ?rst and second
`longitudinal ends, a wiper edge de?ned along the
`length thereof from said ?rst longitudinal end to
`said second longitudinal end, and a substantially
`?at mounting face de?ned along the length thereof
`from the ?rst longitudinal end to the second longi
`tudinal end and opposed to said wiper edge; and
`an elongate, curved backbone having ?rst and second
`longitudinal ends and a substantially ?at mounting
`surface de?ned along the length thereof from said
`?rst longitudinal end to said second longitudinal
`end, said backbone being secured to said wiper
`blade so that said_mounting surface is in opposed
`facing relation to said mounting face of said wiper
`blade, said curved backbone being substantially
`coextensive with said wiper blade, said backbone
`having a generally rectangular cross-sectional pro
`?le along at least a substantial portion of the length
`thereof, said backbone being formed from a resil
`iently ?exible material and having a connecting
`formation projecting from a position intermediate
`said ?rst and second longitudinal ends, said con
`necting formation providing a means for connec
`tion to a displacing and force applying member;
`at least one of a thickness of said backbone and a
`width of said backbone gradually decreasing along
`at least a ?rst portion of said backbone, which is
`de?ned between said position and said ?rst longitu
`dinal end;
`the backbone being curved in a plane, and the back
`bone having a cross-sectional pro?le and a free
`form curvature which vary along its length, and
`wherein the second differential of the function
`M(x) increases along said ?rst portion towards said
`?rst longitudinal end, where
`
`all positions. This is also the case with the shorter side of
`25
`the third example.
`The invention is not limited to the precise details as
`herein described. For example it is not essential that the
`backbone of the wiper tapers uniformly from the centre
`down towards the tips and in some applications the load
`distribution of the blade on the glass of a speci?c wind
`shield may need to increase only towards one tip of the
`wiper. Additionally, as indicated above, to achieve a
`constant angle of wipe of the blade 12 along its length it
`may be necessary to shed the distributed blade load at
`the tip portions of the wiper.
`I claim:
`1. A windscreen wiper assembly comprising:
`an elongated wiper blade having ?rst and second
`longitudinal ends, a wiper edge de?ned along the
`length thereof from said ?rst longitudinal end to
`said second longitudinal end, and a substantially
`?at mounting face de?ned along the length thereof
`from the ?rst longitudinal end to the second longi
`tudinal end and opposed to said wiper edge; and
`an elongate, curved, one-piece backbone having ?rst
`and second longitudinal ends and a substantially
`flat mounting surface de?ned along the length
`thereof from said ?rst longitudinal end to said sec
`ond longitudinal end, said backbone having a cross
`sectional pro?le de?ning a thickness and a width
`thereof, said backbone being secured to said wiper
`blade so that said mounting surface is in opposed
`facing relation to and in substantially continuous
`contact with said mounting face of said wiper
`blade, said curved backbone being substantially
`coextensive with said wiper blade, said backbone
`being formed from a resiliently ?exible material
`and having a connecting formation projecting from
`a position intermediate said ?rst and second longi
`tudinal ends, the thickness of said backbone being
`greater at said position, said connecting formation
`providing a means for connection to a displacing
`and force applying member;
`the thickness of said backbone gradually decreasing
`along at least a ?rst portion of said backbone,
`which is de?ned between said position and said
`?rst longitudinal end;
`
`50
`
`55
`
`65
`
`ale).
`M") = Ron
`
`Costco Exhibit 1005, p. 9
`
`

`
`11
`
`5,325,564
`
`12
`
`5
`
`with
`E=the modulus of elasticity of the backbone;
`I(x)=the cross-section moment of inertia of the
`backbone about a neutral axis at a distance x
`from said position transverse to the plane of
`curvature; and
`R(x)=the free-form radius of curvature of the
`backbone in the plane of curvature at x.
`6. A windscreen wiper as in any one of claims '1-5,
`wherein when the backbone is pressed downwardly at
`the connecting formation onto a flat surface by said
`force applying member with a force suf?cient to
`straighten the backbone, the force per unit length ex
`erted perpendicularly to the surface increases progres
`sively along said ?rst portion.
`7. A windscreen wiper as in any one of claims 1-5,
`wherein said ?rst portion extends from said position
`substantially to said ?rst end.
`8. A windscreen wiper assembly comprising:
`an elongated wiper blade having ?rst and second
`longitudinal ends, a wiper edge de?ned along the
`length thereof from said ?rst longitudinal end to
`said second longitudinal end, and a substantially
`25
`?at mounting face de?ned along the length thereof
`from the ?rst longitudinal end to the second longi
`tudinal end and opposed to said wiper edge; and
`an elongate, curved backbone having ?rst and second
`longitudinal ends and a substantially ?at mounting
`surface de?ned along the length thereof from said
`?rst longitudinal end to said second longitudinal
`end, said backbone having a cross-sectional pro?le
`de?ning a thickness and a width thereof, said back
`bone being secured to said wiper blade so that said
`mounting surface is in opposed facing relation to
`said mounting face of said wiper blade, said curved
`backbone being substantially coextensive with said
`wiper blade, said backbone being formed from a
`resiliently ?exible material and having a connect
`ing formation projecting from a position intermedi
`ate said ?rst and second longitudinal ends, said
`connecting formation providing a means for con
`nection to a displacing and force applying member;
`the thickness of said backbone gradually decreasing
`along at least a portion of said backbone between
`said position and a point spaced from said ?rst
`longitudinal end, the thickness remaining constant
`from that point to the ?rst longitudinal end;
`the backbone being curved in a plane, and the back
`bone having a cross-sectional pro?le and a free
`form curvature which vary along its length, and
`wherein the second differential of the function
`M(x) increases along said portion towards said
`point, where
`
`65
`
`E ' I x
`M(x) = —R(-x-)LL
`
`with ’E-~the modulus of elasticity of the backbone;
`I(x)=the cross-section moment of inertia of the
`backbone about a neutral axis at a distance x
`from said position transverse to the plane of
`curvature; and
`R(x)=the free-form radius of curvature of the
`backbone in the plane of curvature at x.
`9. The wiper claimed in claim 8, in which the distance
`from said point to said ?rst longitudinal end is at least 20
`mm.
`10. A windscreen wiper as in claim 8, wherein the
`width of said backbone gradually decreases along said
`backbone, from said position to said ?rst longitudinal
`end.
`11. A windscreen wiper as in claim 8, wherein when
`the backbone is pressed downwardly at the connecting
`formation onto a ?at surface by said force applying
`member with a force suf?cient to straighten the back
`bone, the force per unit length exerted perpendicularly
`to the surface increases along said backbone from said
`position at least to said point.
`12. A windscreen wiper as in claim 8, wherein said
`portion extends from said position to said point.
`13. The wiper claimed in any one of claims 1, 5, 8, in
`which
`
`where M"(x) is the second differential of M(x); A and C
`are determinable constants; and n is greater than unity.
`14. A windscreen wiper as in any one of claims 1, 5,
`8, wherein the backbone has a rectangular transverse
`cross-sectional pro?le along a substantial part of its
`length and in