As more fully disclosed in U.S. Pat. No. 5,634,283, on which I am the named inventor and the disclosure of which is hereby fully incorporated herein by referende, it has long been a challenge to those of skill in the art of designing footwear to devise footwear having soles that enable the wearer to have traction on surfaces that may be classified as slippery, e.g., ice or wet sod. With regard to the lastter surfaces, golf shoes are a common expedient. Gold shoe normally have soles with metal spikes or studs that extend at right angles to the bottom surface of the sole, so that when the golf shoes are worn on sod, the spikes readily penetrate the sod to a depth such that, when the golfer exerts downward pressure on the shoe sole, the footwear remains in a fixed position relative to the sod despite substantial torque that is applied by the golfer during his swing.
It will be apparent, however, that while shoes having soles with spikes extending outwardly from them are quite useful when one is walking on sod, or even a surface such as ice or compacted snow, when one then stands on a hard, smooth surface into which the spikes can make no substantial penetration, such spiked footwear can be a hazard to the wearer as well as the hard surface, which can be defaced and scratched by the shoe spikes.
In order to address this problem my prior patent disclosed and claimed a footwear sole formed from a resilient material such as rubber and having a plurality of metal studs mounted in the sole, each stud or spike having an anchoring poortion embedded in the resilient sole, a tip portion extending outwardly from the sole surface, and a shaft portion joining the tip and the anchor of the stud. When the footwear is worn, the studs are retracted inwardly from the surface of the sole so that on a hard surface, the tip portions of the studs will be located at the relatively hard surface and will not penetrate it. However, when the wearer is standing on a relatively soft surface, such as sod or wet ice, the studs will extend outwardly from the sole a distance sufficient to enable the wearer to obtain purchase on that softer surface due to penetration of the studs into the surface.
While that invention is broadly utilitarian, i6 does not address problems that may arise in specific situations. Thus, where a woman's shoe is to be made with such a sole, it is apparent that pressure on the resilient sole will be less than that exerted by a shoe where the wearer is a 300-lb. man. Moreover, if the sole is formed from rubber or other material of a high degree of resilience such tht when the shoe is worn by a lightweight person the studs will nevertheless retract to the bottom surface of the sole, the sole formed from such soft rubber may not present a firm support to the wearer. In addition, even when there is an optimum balance between the resilience of the sole and the weight of the wearer, there still may be some scarification of a hard surface when the wearer i of the shoes slides his or her feet across that surface.
It is, therefore, one object of the present invention to provide a studded sole for footwear in which the resilience of the sole at its bottom, work-contacting surface is not necessarily determinative of the resistance of the sole to retraction of the studs while the footwear is being worn.
Expressed otherwise, it is an object of my invention to overcome the problem of adapting a studded, resilient sole to varying surface and weights of the wearer so that the studs will readily engage surfaces on which they are designed to penetrate, but nevertheless enable the wearer to utilize the shoes or other footwear on a hard surface, such as a tile floor, without unduly marring that surface.