[0001] This invention is concerned with knitted hosiery for men, women and children. The
invention is directed specifically to socks having a leg length not extending above
the mid-calf part of the human leg when in normal position (position of minimum energy)
during wear. Included in this category of socks are items known as "short socks",
"ankle socks", "anklets", "half hose", "crew socks", "below-the-calf socks", "mid-calf
socks".
[0002] Hereinafter the term "socks" will mean knitted garments for clothing the foot and
leg that do not extend above the mid-calf of the leg of the wearer when in the normal
wearing position and composed of a fabric having less than about 105 stitches per
square centimetre (700 stitches per square inch) when measured fully stretched in
course and wale directions and at standard conditions for testing textiles.
[0003] In the period, prior to approximately 1935, socks, as distinct from stockings which
reached over the knee, were chiefly of a length reaching to the wearer's knee, or
else to the mid-calf part of the wearer's leg, the latter being known as "half-hose".
In order to restrain the leg of the knee length socks from slipping down a wearer's
leg whilst walking, circular garters generally made from rubber elastic braid were
used. The leg of the half-hose type of sock was restrained from slipping by suspenders,
attached to the wearer's leg between the knee and calf muscle, and clipped to the
top of the leg of the sock.
[0004] Approximately forty to fifty years ago technology was developed for the laying of
rubber elastic thread into the stitches of knitted fabric, and this technology was
used to produce socks with such thread laid into a number of knitted courses at the
top of the leg of socks. The thread so laid into the knitted fabric constituted an
elastic band at the top portion of a sock leg, and in reference to it the term "elastic
top" is commonly used.
[0005] The purpose of the elastic top was the incorporation within the sock of means of
restraining the leg portion from slipping down a wearer's leg during walking, thus
eliminating the need to have extraneous means of restraint as described above. The
elastic top in a below-the-calf sock is stretched when initially placed on the leg
and thus grips the leg of a wearer. After a period of wearing, during which the wearer
walks with a normal gait and velocity of leg, it is usuel for a sock to progressively
slip down the wearer's leg, forming wrinkles in the fabric of the lower part of the
leg of the sock. This slippage commonly occurs even when the elastic top exerts pressure
on the leg od such magnitude as to cause temporary skin indentation and irritation.
[0006] It is the purpose of the present invention to provide socks, with leg length not
extending above the mid-calf position of wearer's legs, and which exhibit superior
resistance to slipping down wearer's legs during walking also causing minimal and
generally negligible skin indentation or skin irritation.
[0007] It is recognized that the part of the human leg, from the location of mid-calf to
the location of minimum circumference, is approximately the shape of an inverted truncated
cone. When a sock is drawn on to the leg of a wearer and located in a normal position
for wear, the fabric of the leg portion of the sock usually exerts a pressure on the
leg of the wearer and this sock-to-leg pressure will generally vary according to position
between the two locations referred to above. The pressures are exerted as a consequence
of the varying circumferential extentions giving rise to varying circumferencial tensions
within the fabric of the leg of a sock.
[0008] At any one place between the two locations indicated above (mid-calf and minimum
leg circumference), the force exerted by the fabric on to the leg in a circumferencial
plane is, by virtue of the shape of the leg, not normal to the leg surface. It may,
therefore, be resolved into two components, one being normal to the leg surface and
the other one downwards along the leg surface, a fact to which reference is made hereinafter.
[0009] When a sock is first donned by a wearer, and the top margin pulled some distance
up the leg, its leg fabric is usually in a stretched state through tension being applied
in the action. The individual stitches are in an elongated and stretched condition.
When the wearer starts to flex a leg and move it gently the stretched stitches will
change from their elongated to a more rounded form. This form approximates to an equilibrium
position for a leg in gentle movement.
[0010] When the wearer commences prolonged walking whether continuous or intermittent, two
main groups of forces are acting on the leg fabric. In the first group are those which
favour slipping of the leg fabric down the wearer's leg accompanied by wrinkling (or
buckling) of the fabric, while in the second group are those forces which resist slipping
and wrinkling of the leg fabric.
[0011] For a leg involved in the motion of walking the chief pro-slip forces are:-
(a) That component of the force exerted by the leg fabric acting downwards along the
surface of the leg.
(b) That component of the gravitational force acting on the mass of the leg fabric
parallel to the surface of the leg,
(c) That component of the force resulting from the momentum of the sock fabric, the
velocity of which changes each time the wearer's foot touches the ground.
(d) That resulting from the friction between the leg fabric and the skin of the wearer,
(e) That arising from the fabric below any portion which is tending to slip and which
is due to resistance to displacement as regards location that is, slipping downwards,
or to configuration, that is, to wrinkling.
[0012] If the sum of the forces "a", "b" and "c" is greater than the sum of the forces "d"
and "e" in any portion of the leg fabric then conditions exist for the fabric to slip
down the leg. This slipping will continue until conditions change to make the sums
of the two groups of forces equal at which stage further slipping and wrinkling do
not occur.
[0013] In constructing a sock in which the leg fabric will not slip down the leg from the
position of equilibrium described above, it is necessary to ensure that the sum of
the forces "a", "b" and "c" is less than the sum of the forces "d" and "e" by minimizing
the magnitude of the pro-slip forces and maximizing the magnitude of the contra-slip
forces.
[0014] It has been discovered that by varying in a selected manner the circumferential tensions
of the leg fabric of the socks and accordingly the fabric-to-leg presure, there can
result socks in which the leg portion resists slipping down the wearer's legs during
walking.
[0015] The present invention relates to a knitted sock according to claim 1
[0016] It has been found that a leg fabric which resists slipping down a wearer's leg can
be constructed initially by providing a portion of fabric around the place where the
leg has minimum circumference and extending it down to the ankle joint.
[0017] This portion of fabric has moderate to high circumferential tension whilst on the
leg and, therefore, moderate to high fabric-to-leg pressure. Then there is required
a decreasing of the circumferencial tension and fabric-to-leg pressure at a selected
and relatively rapid rate whilst proceeding from the region of minimum leg circumference
to the top margin of the sock.
[0018] The ability of a sock of such construction to resist slipping down the leg of a wearer
may be explained by considering the leg of the sock as a series of bands of fabric
(as illustrated in Figure 1).
[0019] The portion of fabric at the minimum leg circumference (band 1) and extending down
to the ankle joint is located on an approximately conical shaped section of the wearer's
leg and, therefore, the circumferencial fabric tension has a force component 'parallel'
to the leg surface tending to push the fabric upwards. Thus the position of fabric
at the minimum leg circumference possesses an added ability to resist displacement
downwards. Frictional resistance is also present.
[0020] For the narrow band of fabric (2) in Figure 1 to be able to slip downwards, it must
either displace downwards the fabric band (1) or cause this band to form a wrinkled
or buckled section (x). Fabric band (1) resists slipping downwards as already explained,
however.
[0021] It should be noted that the action of the leg fabric of a sock becoming wrinkled
involves an increase in fabric circumference and, therefore, an increase in circumferential
tension in the wrinkled fabric. thus incipient buckling or micro-wrinkling, should
it occur, will contribute to the contra-slip forces to resist slippage of band (2).
This contributed force would act upwards from the wrinkle, in the leg fabric and parallel
to the surface of the wearer's leg. It has been found that with suitably selected
values for circumferential tension in bands (1) and (2), no slipping or wrinkling
or fabric occurs in wearing and walking.
[0022] In a similar way the possibility of fabric band (3) slipping and causing band (2)
to slip or wrinkle can be considered. With optimum selected values of the circumferential
tension in the respective bands, no slipping or wrinkling will occur. The whole of
the leg fabric can be considered in this way and found to be free from slipping and
wrinkling.
[0023] The practice of using slowly varying fabric-to-leg pressures has been employed in
surgical or therapeutic hosiery, "leg-support" or "support" stockings, pantyhose and
socks. All these articles are designed with concern for the blood circulation in the
human leg and from the recommended pressure differentials between minimum leg circumference
and other locations up the leg, it can be calculated that the principle applying in
the more effective articles is for the circumferential tension in the leg fabric of
the article on a wearer's leg to remain substantially and approximately constant over
the whole leg.
[0024] Examples of such an article or therapeutic hosiery are described in various United
States Patents which state that the compressive force is substantially uniform throughout
the length of the article when in use.
[0025] In regard to the desirability of a uniform compressive or constrictive force in therapeutic
hosiery we would refer in particular to USP 2,441,443 Col. 5 lines 35 to 44, and USP
3,386,270 Col. 1 lines 27 to 59.
[0026] In other therapeutic or support hosiery there has been proposed variation in the
fabric-to-leg pressure along the length of the leg, such as in USP 3,889,494, however
there is no suggestion that the full length stocking described has stay-up characteristics.
Further as there is a substantial reduction in fabric-to-leg pressure in the knee
area, the portion of the stocking above the knee would not be non-slipping in the
manner proposed by the present invention. It should also be noted that in the area
of the leg immediately above the knee there is a progressive increase in fabric-to-leg
pressure while the leg in this area is progressively increasing in diameter. These
two facts have a cumulative effect promoting downward slipping of the stocking.
[0027] The use of progressively increasing horizontal constriction in the welt of a stocking
is proposed in USP 3,392,553 which is stated to be applicable to both above the knee
and below the knee stockings or stocks. However the purpose of the variation in the
constriction is stated to be to achieve "uniform or equal compressive force against
all areas of contact with the wearer's leg". This is contrary to the present invention
and would not achieve the non-slip property in the manner of the present invention.
Also is must be noted that it is only proposed for the variation in constriction to
exist in the welt of the stocking or sock which is then merely an elasticized top
type stocking or sock.
[0028] The problem of constructing knitted socks having a leg part not extending above the
mid-calf of wearer which do not slip down the leg of the wearer is discussed in DE-A-
2 820 480 and a solution proposed which involves decreasing the circumfential tension
in the sock from the ankle upwards. However, DE-A-2 820 480 contains no clear teaching
as to how this concept is to put into practice.
[0029] In orderto characterize the socks of the present invention, and to differentiate
them from surgical and therapeutic hosiery, and also from socks with elastic tops
and those with constant course lengths of yarn in the portion up to the calf, and
support socks tests for fabric pressure have been made.
[0030] Due to the novelty of the concept of the type of sock of the present invention there
is no widely recognized or standard testing apparatus and method for fabric-to-leg
pressure exerted by socks. It has therefore been necessary to choose an apparatus,
adapt it for use with socks and develop a test method.
[0031] Of the two widely recognized testing instruments and methods for leg support hosiery
namely "Support Hosiery Testing Apparatus and Method", USP 3,975,956 invented by Robert
Peel and assigned to National Association of Hosiery Manufacturers Inc., Charlotte,
N.C. U.S.A. and the "Hatra Hose Pressure Tester", developed by Hosiery and Applied
Trades Research Association, Nottingham, England and manufactured by Shir- ley Developments
Ltd., Manchester, England, both based on the same principle but differing in design,
the latter was selected merely because it was more readily adaptable to the testing
of socks. It provides a measure of circumferential fabric tension which can be converted
to fabric-to-leg pressure for leg locations having varying radii of curvature.
[0032] The adaptation of the Hatra Hose Pressure Tester involves replacing the woman's foot
portion by appropriately larger ones for mens' socks and appropriately smaller ones
for children's socks then extending the suspender clips from the locations existing
for hosiery of which the legs extend above a wearer's calf, so as to be able to secure
during test various socks with legs which extend to locations below a wearer's calf.
Additional modification for testing children's socks involves replacement of the fixed
and removable arms by ones with smaller cross section.
[0033] For purposes of specification of socks of the present invention and control of quality
in manufacture various appropriate settings of the Hose Pressure Tester have been
adopted. For men's socks designed to fit wearers of socks sizes 10 to 12 inclusive
(foot length 10 inches to 12 inches or 25 cm to 30 cm corresponding to shoe sizes
6 to 10, -Australian shoe sizes 6 to 10 correspond to American sock sizes 10 to 13,
indusive-refer Australian Standard 1923-1976) the setting adopted was the "M" position
of the movable arm. When a sock is pulled on to the "V" formed by the fixed and movable
arms, it assumes the appropriate configuration that it would have on the leg of male
wearer whose leg dimensions are the average for the population within this sock size
range.
[0034] Since the "M" position is the one designated for women's surgical, therapeutic ans
support stockings and pantyhose comparison and contrast can be made between the pressure
generated by these hosiery items at various locations on the leg and by the socks
of the present invention.
[0035] Furthermore, since circumferential lengths for the average leg in various populations
requiring the one sock size (men, women and children) can be closely matched on the
Hatra Hose Pressure Tester (in original or modified form) figures for fabric-to-leg
pressures on average legs are considered to closely approximate to those obtained
by use of the Tester.
[0036] The purpose of Table I is to indicate the fabric-to-leg pressures applicable to all
socks of the present invention and contrast these with pressure figures indicated
in two prior United States Patents, a recognized quality standard, a recommended quality
standard ans also with pressure figures which are typical of three types of men's
socks of conventional type.
[0037] It is seen that socks of the present invention differ markedly and, therefore, belong
to a different class of garment to conventional socks and to surgical, therapeutic
and leg-support hosiery and support socks and are characterized by a much greater
decrease of fabric-to-leg pressure from the location of minimum leg circumference
to mid-calf.
Figures in each column are fabric-to-leg pressures expressed as a percentage of the
pressure at the minimum leg circumference of each item.
Ref. 1 USP Re 25,046 Oct. 3 1961. Example 111: Pressure in ankle 20 mm of mercury,
in calf 19 mm and in lower thigh 18 mm.
Ref. 2 Technical Production Guidelines for Two-Way Stretch Surgical Stockings with
the Quality Mark.
[0038] (Quality Mark Association for Surgical Elastic Stockings, Hohenstein, W. Germany,
1972).
[0039] Ref. 3 Levels acceptable for therapeutic value: (Consumer Bulletin Sept., 1972, pages
32-35, Consumers Research Inc., Washington, U.S.A.).
[0040] Ref. 4 USP 3,386,270 June 4 1968. From the statement in this patent that the compressive
force on the ankle (minimum leg circumference) may be the same as on the remaining
portions of the leg, it can be deduced that for a minimum leg circumference of 24
cm and a mid-calf circumference of 35 cm which are the average figures for men wearing
sock size 6-10 (Australian) that the ratio of fabric-to-leg pressures at the two positions
is 100 to 69.
[0041] As previously referred to in the case of socks of the present invention of which
the of the legs is such that the marginal portion of the sock reaches a point below
the mid-calf of wearer's legs when the fabric is in the normal position of wear, the
percentage figure for the minimum decrease of fabric-to-leg pressure from the minimum
leg circumference to the top marginal location will be the same proportion of 40%
as the distance between the minimum leg circumference and top margin of the sock is
to the distance between the minimum leg circumference and the location of the mid-calf
circumference.
[0042] Table II illustrates this case.

[0043] As is has been recognised that friction between sock fabric and the wearer's skin
helps the sock to resist slipping down the leg as a result of walking, then it follows
that fabric-to-leg pressures must be adequate to give rise to some useful frictional
force even in the upper parts of the leg of the sock where the fabric tensions may
be relatively low.
[0044] It is common practice to design a sock to fit a range of one or more foot sizes.
Such foot sizes may be designated by shoe size or by foot length according to the
system used. Within any range of one or more foot sizes, the contours of the feet
and legs of the population of wearers vary and in this particular case, those portions
of legs located below the knee. The one design of sock is, nevertheless, expected
to fit not only wearers' feet of varying dimensions but also wearers' legs of varying
dimensions. Socks with the characteristics of this invention can exhibit resistance
to slipping down wearers' legs and minimal or negligible skin indentation or skin
irritation for a high percentage of any population of wearers and for selected values
of sock characteristics this percentage will exceed 90%.
[0045] The performance in wear exhibited by the socks of the present invention differs noticeably,
therefore, from that of mid-calf and below the calf socks having the prior known elastic
tops. In these latter types of percentage of population which finds resistance to
slipping down the leg during walkingtogether with freedom from skin indentation and
skin irritation may be as low as 10%. The production of socks with legs not extending
above the mid-calf, without discrete elastic tops, but with an elastic yarn knitted
or laid into the whole length of the leg fabric with constant yarn length per course
does not greatly increase the percentage of a population of wearers with socks which
resist slipping down their legs during walking.
[0046] The required fabric-to-leg pressure of the sock may be achieved by incorporating
elastic threads into the fabric of the sock. These threads may be made either wholly
or partly of elastomeric material and/or textured or otherwise processed polymeric
filament or fibre imparting elastic quality to the thread.
[0047] The variation in the pressure may be achieved by varying the quantity of elastic
thread or by varying the tension in the thread during the actual incorporation thereof
into the fabric. The variation in tension may be obtained by variation in the form
or size of stitch used.
[0048] The behaviourofthe socks in resisting slippage down the leg as a result of walking
is assisted by a relatively high fabric-to-leg friction, such as can be obtained with
the use of spun yarns in the knitted fabric, and particularly but not necessarily,
spun yarns containing wool or cotton.
[0049] Asuitable knitting machine for production of a sock according to the present invention
is one in which there is the capability of altering the length of all or some of the
yarns fed (knitted or laid) into the knitted needles at each knitted course or at
predetermined intervals during the knitting of the leg of the sock and/or varying
the feed pattern for yarns. As an example of the second alternative a particular yarn
may be fed into the needles at every course, every second course, or not at all (varying
the yarn course density).
[0050] Knitting machines may have cylinders varying in diameter from approximately 2% inches
(6 cm) to approximately 6 inches (15.2 cm) and may have a number of needles varying
from 36 to 280.
[0051] Fabric construction may be plain knit (also known as single jersey), rib knit or
jacquard knit.
[0052] Sock construction may include a heel pocket knitted by a reciprocating action, or
it may be of a "tube" type without such heel product and with or without yarn knitted
or laid into the tube fabric to form a heel patch. Knitting yarns employed in the
production of the sock may be any of those commonly used in the present art. Such
yarns may be spun from the following fibres: cotton, wool, acrylic, polyamide, polyester,
regenerated cellulose or may be continuous filament yarns of the following types:
polyamide, polyester, regenerated cellulose, spandex (segmented polyurethane), rubber
(natural or synthetic). In addition knitting may be performed from any mixtures of
any two or more of any of the above mentioned fibres or continuous filaments in the
form of blended mixtures, twisted mixtures or as core-spun yarns or wrapped fibres
or filament yarns.
[0053] This invention particularly concerns the leg portion of the sock, the knitting of
the leg and the setting of the leg fabric.
[0054] After completion of the knitting of the leg of the sock, the knitting of the heel,
foot and toe is performed according to the chosen design of sock, and according to
known art. Following completion of knitting the toe opening (if present) is closed
by any of the present available means.
[0055] It is an optional current practice to place a sock, if it contains some fibre which
can be plasticized by heat and steam on a flat metal former of a shape a little larger
than that of the sock in a flat relaxed state. Socks fitted to former are placed in
an autoclave and subjected to steam presure, or in other vessels and subjected to
heat, in order to achieve a moulding and setting of the sock fabric and thus a certain
shape to the sock. Depending on whether this is done before or after scouring and
dyeing it is known as pre-boarding or post- boarding respectively.
[0056] In order to assist in the practical application of the present invention examples
of constructions of sock will now be described with reference to Figures 1, 2 and
3 of the accompanying drawings. The socks in the examples are intended forfitting
the Australian adult male population, the leg and foot characteristics of which are
similar to those of many other nationalities. To fit nationalities with different
foot and leg characteristics small modifications may be required but the same principle
relating to the rate of decrease of fabric circumferential tension and fabric-to-leg
pressure from minimum leg circumference to the top margin of the sock will apply.
Example 1
[0057] The sock shown in Figure 2 is knitted on a 3-feed KometTJ2 knitting machine also
having for each diameter N176 needles. The sock has in the leg portion between the
lines A and G, a fabric construction of 1 x 1 rib type. Characteristics of the fabric
in the respective sections of the portion of the sock (to fit size range as specified
in Example 2), are shown in the following table.

[0058] In this example the required variation in fabric-to-leg pressure is obtained by varying
the number of courses of 235 dtex Spandex relative to the total number of courses
in the respective sections of the sock.
[0059] This sock provides comfortable fit without skin irritation and will resist slipping
down the leg of 90% of that population of wearers for which it was designed.
Example 2
[0060] In this example there is a continuous decrease in fabric tension and fabric-to-leg
pressure in a portion of the sock between E (refer to Figure 3) which is approximately
the position of minimum leg circumference and D.
[0061] This is effected by continuously varying the stitch size of the 1/57 tex yarn and
the course length of the 235 dtex double covered spandex. The Knitting Machine in
this example is an Esta, Model JU3 with 4 inch cylinder diameter and having 176 needles.
[0062] Details of yarn and characteristics of the respective sections of the leg of the
sock (fitting men with foot length of 10 to 12 inches inclusive or 25 to 30 cm corresponding
to shoe sizes 6 to 10 inclusive) are shown in the following table.

[0063] This sock provides comfortable fit without skin irritation and will resist slipping
down the leg of over 90% of that population of wearers for which it was designed.
[0064] In all the above examples, after completion of knitting the toe openings of the socks
were closed by seaming. The socks were then scoured at 45°C in an aqueous medium containing
an appropriate detergent, rinsed, dried, placed on metal shapes in an autoclave, subjected
to steam for from 40 to 50 seconds at a temperature in the range of 119°C to 124°C,
and excessive moisture removed by convection drying with hot air.
[0065] While the foregoing examples and tables have referred to men's socks which by virtue
of a "stretch" yarn and/or thread component have fitted a range of foot sizes corresponding
to shoe sizes 6 to 10 inclusive, the present invention may be employed to provide,
additionally, socks of the following types with the top margin below the mid-calf
[0066] Men's socks in which one design (or construction) fits only one foot size.
[0067] Men's socks designed to fit foot sizes greater than corresponding to shoe size 10
(Australian) or equivalent.
[0068] Women's socks of any foot size and design.
[0069] Children's socks of any foot size and design.