Moisture retention athletic sock having resilient cushioning attachment

An athletic sock is formed out of a moisture-absorbent yarn material that is knitted to conform to the shape of a human foot. A flexible sheet of neoprene, or similar resilient thermal insulator material, is affixed to the moisture-absorbent fabric so as to overlie the shin area, ankle area and instep area of the sock. The neoprene sheet acts as a cushion between the person's boot and foot so as to improve foot comfortability. The neoprene sheet also acts as a thermal barrier to control the escape of heat and moisture from the sock areas in contact with the neoprene sheet.

BACKGROUND OF THE INVENTION 
1. Field of The Invention 
This invention relates to athletic socks, particularly socks worn in 
relatively stiff boots, where foot comfort may be a problem. Socks of the 
present invention are especially designed for use by persons engaged in 
winter sports, e.g. ice skating, skiing, mountain climbing, outdoor 
camping and snowboarding, where boots are worn. 
2. Prior Developments 
Persons engaged in winter sports often wear relatively stiff boots, as 
protection against snow or the weather elements entering into the footwear 
to thereby make the feet feel unconfortable. However, the stiffness of 
many boots is itself a source of foot discomfort. The problem is more 
difficult since the boot has to feel comfortable, while at the same time 
keeping the feet warm. One solution is to wear multiple pairs of socks, so 
as to increase the cushioning action and the thermal insulative action. 
Boots used in snowboarding have metal eye loops and laces that can be a 
source of foot discomfort. The binding system requires the wearer to 
buckle the binding down tight into the foot, which in turn presses the eye 
loops of the boot into the top (instep) of the foot, causing some foot 
discomfort. Boots used in other sports, such as ice skating, skiing and 
hiking, have similar problems. The problem of keeping the feet comfortable 
and warm in sub-freezing temperatures, is affected partly by the fact that 
sweat or moisture generated by the athletic activity (e.g. ice skating) 
tends to work through the sock so as to form a thermal bridge between the 
boot and the person's foot. Heat travels from the foot through the 
relatively conductive moist sock material to the relatively cold boot, 
thereby rapidly cooling the foot to an undesirably cold and uncomfortable 
condition. 
In an effort to avoid such undesired heat loss there have been developed 
socks formed of imperforate neoprene. The neoprene, in sheet form, acts as 
a thermal barrier to slow down, or completely stop, the escape of heat 
from the person's foot to the boot. An imperforate neoprene sock fully 
encircling the person's foot is however not fully satisfactory, since it 
may prevent the foot from perspiring or breathing in normal fashion. The 
complete thermal barrier provided by an imperforate neoprene sock traps 
sweat between the persons's skin and the neoprene surface, such that a 
resistance to further sweating is established. The foot senses the 
resistive condition and stops sweating, thereby eventually causing the 
skin surface to cool down to an undesired extent. 
Various porus, moisture-abosorbent socks have been developed as an 
alternative to the imperforate neoprene sock. U.S. Pat. Nos. 3,341,096 and 
4,898,007 and 5,095,548 are representative patents showing socks knitted 
out of various hydrophilic and hydrophobic yarns in different 
combinational arrangements, so as to control the escape of moisture from 
the person's foot. 
A hydrophilic yarn, such as cotton, is moisture-absorbing and moisture 
conducting, so as to act like a wick for transporting moisture from a 
relatively wet area of the sock to a relatively dry area. A hydrophobic 
yarn has relatively slight affinity for water, such that the moisture 
tends to collect on the yarn surface, where it can be removed by 
evaporation or collect as free condensate, depending on its temperature. 
The above-mentioned patents show sock constructions, wherein some areas of 
the sock are formed primarily of hydrophilic yarns, and other areas of the 
sock are formed primarily of hydrophobic yarns, whereby moisture generated 
by the person's foot is transported to specific areas of the sock for 
evaporative removal. Heat is retained in the in the moist sock material so 
as to keep the person's foot relatively warm and comfortable. Water has a 
relatively high specific heat, so that a relatively thin film of water on 
the sock is able to hold relatively large quantities of heat. 
The porosity of the knitted socks described in the above-noted patents, may 
be a problem in that the moistened yarns and yarn surfaces may form 
unobstructed thermal paths between the person's foot and the boot interior 
surface, such that the socks will not serve their intended when worn for 
prolonged periods of time in sub-freezing conditions. 
U.S. Pat. No. 4,373,361 to I. Thornelburg, shows a knitted ski sock formed 
of hydrophilic and hydrophobic yarns for heat management purposes. 
Additonally the yarn layers are increased or thickened in selected areas 
of the sock so as to form a cushion between the boot and the person's 
skin. The cushion acts as a spacer, thereby making the sock more 
comfortable on the person's foot. 
SUMMARY OF THE INVENTION 
The present invention relates to an athletic sock that comprises a knitted 
porous fabric formed out of moisture-absorbing yarn, e.g. cotton, and 
having a flexible covering sheet of neoprene, or similar thermal insulator 
material, extending over the shin area, ankle area and instep area of the 
sock. Other areas of the sock, e.g. the toe, heel and sole, are left 
uncovered. 
The flexible covering sheet acts as a cushion to prevent forcible pressure 
contact between the hard boot and the shin, ankle and instep areas of the 
person's foot, as would make the boot feel uncomfortable. The flexible 
covering sheet also forms a thermal barrier between the boot and the sock 
areas in direct contact with the person's ankle, shin and instep, whereby 
those areas of the foot are kept relatively warm. 
The flexible neoprene covering is concentrated primarily on the the 
upwardly facing, (or forwardly facing) areas of the sock, such that the 
sock has approximately the same flexibility and stretchability as a 
conventional cotton athletic sock. When worn, the sock of the present 
invention has essentially the same feel as a conventional sock, as regards 
stiffness, flexibility and stretchability. 
The sole area of the sock provides a zone where moisture can collect and 
possibly vaporize. Moisture generated on the sole area of the foot has an 
escape path around the neoprene barrier sheet so that the foot is allowed 
to perspire in an essentially normal fashion. Heat generated by the 
perspiring foot is allowed to escape in a controlled fashion, while the 
foot is kept relatively warm.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
FIG. 1 shows an athletic sock comprising a knitted porous fabric 10 formed 
out of a moisture-absorbing yarn material, e.g. cotton yarn. The fabric 
material is adapted to fit closely (snugly) on a person's foot within a 
boot, not shown. The fabric sock is particularly intended for use by 
person's engaged in winter activities, such as ice skating snowboarding, 
skiing, hiking, and camping; the boot will be selected according to the 
particular activity involved. 
Fabric 10 comprises a tubular area 12 adapted to encircle the lower leg 
area of the person (including the shin), a second area 14 adapted cover 
the person's heel, a third area 16 adapted to surround the person's toes, 
a fourth area 18 adapted to underlie the sole of the person's foot, and a 
fifth area 20 adapted to overlie the instep of the person's foot. 
During an athletic activity moisture generated by the person's foot will 
permeate the knitted fabric 10 so as to form a water film within the pores 
of the fabric and within the moisture-absorbent yarn material. Since water 
has a relatively high specific heat it will retain heat relatively 
efficiently on or near the skin surface. Heat generated within the foot is 
retained by the sock fabric 10 even though the fabric is in a moist (wet) 
condition. 
However, the moist fabric 10 material has a disadvantage in that it acts as 
a thermal conductor between the foot and the relatively cool interior 
surface of the associated boot. The water film on fabric 10 conducts heat 
from the person's foot to the boot. To minimize this conductive heat loss 
the sock is provided with a flexible thermal insulator sheet 22 preferably 
formed of neoprene. The required characteristics for sheet 22 are that it 
be a thermal insulator, flexible, and resilient. Sheet neoprene, having a 
thickness of about 0.08 inches, is a preferred material. 
Sheet 22 is sized and configured so as to extend along shin area 21 (i.e. 
the front surface of tubular area 12), ankle area 23, and instep area 20, 
of the porous fabric sock material 10. Sheet 22 is preferably attached to 
fabric material 10 by stitching that runs along the peripheral edge of 
sheet 22. 
FIG. 2 shows sheet 22 in a flat condition prior to attachment of the sheet 
to the fabric material 10. For illustration purposes the stitching used 
for attaching sheet 22 to fabric material 10 is designated by dashed lines 
25 in FIG. 2. The stiching extends along the entire peripheral edge of 
sheet 22. Additional stitching can be used across the face of sheet 22. 
Sheet 22 has a longitudinal axis 27 and a transverse axis 29. The sheet is 
arranged in fabric 10 so that zone 31 of the sheet overlies the instep 
area 20 of the porous fabric, and zone 33 of the sheet overlies shin area 
21 of the porous fabric. The neoprene sheet material has sufficient 
flexibility that it can wrap transversely around the fabric 10 material so 
as to extend downwardly (or rearwardley) along the side surfaces of the 
sock fabric. 
Central zone 35 of the neoprene sheet has curved side edges 36 spaced 
relatively far away from longitudinal axis 27 such that zone 35 of the 
sheet is wider than the other two zones 31 and 33. Central zone 35 forms 
two ears 37 that are adapted to overlie the ankle area of the sock (above 
heel area 14). In order to insure continuous facial engagement between 
neoprene sheet 22 and fabric sock material 10, without undesired wrinkling 
or buckling of the sheet material, the neoprene sheet is provided with an 
oval cut-out (or opening) 39 in zone 35 of the sheet. When sheet 22 is 
placed over fabric 10 the oval opening 39 is located at the juncture 
between shin area 21 and instep area 20 so as to form a relief opening 
that enables the neoprene sheet to fit smoothly on the fabric 10, without 
distorting the fabric or forming corrugations or folds in sheet 22 when 
the sock is worn. As previously noted, sheet 22 is preferably stitched 
along its peripheral edge to the fabric 10 so as to assume the position 
depicted in FIG. 1. 
Neoprene sheet 22 acts as a thermal barrier to block the thermal path that 
would otherwise exist between the shin area, ankle area, and instep area 
of the sock and corresponding areas of the associated boot. Moisture and 
heat are trapped within fabric 10 and beneath neoprene sheet 22, whereby 
the person's foot is kept relatively warm. 
Sole area of 18 of the sock is uncovered, such that moisture can escape and 
possibly vaporize, depending on temperatures realized by the fit of the 
boot on the person's foot. The escapage of moisture allows the foot to 
breathe and keep perspiring in an essentially normal fashion. 
Neoprene sheet 22 acts as a thermal barrier between the sock and the 
person's boot. The neoprene sheet also acts as a resilient cushion to 
soften the hardness of the contact between the boot interior surfaces and 
the person's foot. The cushioning is provided at those areas of the foot 
where the boot is likely to produce the greatest discomfort, i.e. the shin 
area, ankle area, and instep. 
Neoprene sheet 22 is preferably sized so that its longitudinal length 
parallel to axis 27 is about twice its its transverse width parallel to 
transverse axis 29. Front edge 39 of the neoprene sheet preferably has an 
arcuate semi-circular contour in order to improve the confortability of 
the sock on the person's foot. Neoprene sheet 22 partially wraps around 
fabric 10, such that the finished sock has approximately the same 
flexibility as a conventional knitted cotton sock. 
Neoprene sheet 22 can be imperforate, as shown in the drawings. Alternately 
sheet 22 can have small perforations extending therealong to achieve 
limited escape of moisture from the fabric 10 material in contact with the 
neoprene sheet.