Sandal with springs   

CROSS-REFERENCE TO RELATED APPLICATIONS

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1. Field

This application relates to footwear, and specifically to a sandal having springs.

2. Prior Art

In the prior art sandals have commonly shown to turn uncomfortable over a certain period of time. This discomfort can cause a user pain. The comfort of a sandal is directly related to the means in which it employs cushion—that is, providing the user with a particular type and certain amount of material that will reduce impact levels, and a matter of providing the user with adequate support. So, sandal manufacturers have long sought means of creating various types of cushioning devices that would attempt to fit a wider range of comfort, but the continuation of using traditional materials such as foam, rubber, plastic, etc. and the manner in which these materials have been employed has left their users—especially those whom enjoy walking—wearing sneakers more often than not, solely for the reason that prior sandals can quickly cause discomfort. Both U.S. Pat. No. 1,964,406 to Pellkofer (1931) and U.S. Pat. No. 2,478,664 to Morrow (1946) have attempted to create an improvement in sandal comfort by involving coils. Both have used tension coils. Morrow states “Each spring is in the form of a coiled wire, preferably a piano wire . . . ” Due to the type of springs used and the horizontal positioning of these so called coils they do not provide enough counter pressure to reject the users weight. Tension coils are designed to create a means of pulling two objects towards each other, whereas compression springs are meant to create a rebounding force between separate objects. Also, tension coils provide zero counter pressure in their natural state because they require an outer force to provide tension. In my own improved sandal I use compression springs that are arranged vertically to allow complete contouring of the foot. They also provide an invariant reactive force pushing the user upwards and forwards as they walk.

While the coils in both sandals may contour, neither sandal is adapted to provide enough spring counter pressure that will allow for a comfortable and fully supportive sandal.

One method used with the intent to generate a supportive and comfortable sandal is shown in U.S. Pat. No. 775,440 to Bonney (1903), here a number of coils are situated to form two springs. The object is to provide substantial weight deflection while providing enough springs to comfortably displace the users weight throughout the sole. The sandal does not have enough spring coverage to provide either.

Prior footwear designs have shown springs placed beneath the heel, with others showing springs placed beneath the toe. The majority of prior art has abandoned the extremely important midsection, leaving it spring less. When walking, a natural step involves the heel touching ground first, followed by the midsection then toe. Prior spring configurations will hinder the natural kinetic stepping movement of a user, imputable to an absence of spring interaction beneath the middle part of the foot. They will also reduce comfort and support levels due to the lack of proper weight displacement over what should be an entirety of spring coverage beneath the heel, midsection, and toe of the user. However, even if there are springs placed beneath the heel section, midsection, and toe section of the footwear, their effectiveness can be reduced by several factors: (1) location of springs render too little or too much support in either three sections of the foot, (2) spring rate employed, either provides too little or too much counter pressure, (3) improper arrangement of springs applies too much resistance towards either part of the foot, thereby hindering a natural kinetic step, and (4) improper spring arrangement allows the foot a great deal of lateral movement, and thereby leaves user unbalanced.

Weisz, in U.S. Pat. No. 4,267,648 (1981) shows a shoe with an integrated spring sole. Although this shoe uses springs, they are in the form of disc springs. In comparison to compression springs, disc springs do not offer an equal range of vertical movement, and their applications are usually related to heavy-duty equipment such as machinery employed within the oil industry. In most cases disc springs require more weight to compress the same amount of distance as does a compression spring, and therefore are not suitable to offer a noticeable amount of cushion and shock absorption in the usage of footwear. Also, a disc spring requires an inner hub to function properly, and in Weisz\'s shoe it also requires an outer support system. Weisz states “Disc springs consist essentially of a disc or washer supported at its outer periphery by means of an annular support.” These factors not only lead to higher costs, but the additional requirements of Weisz\'s design make his shoe heavier and more vulnerable to malfunctions. Other aspects of Weisz\'s shoe such as a “spring steel sheet, semi rigid plastic, or the like,” and a hub with outer spring support create extra weight and therefore induce additional shock to the user upon the impact of walking. Also, because a disc spring is not an open-coiled spring it is heavier than an open-coiled compression spring of similar size.

Smith, in U.S. Pat. No. 5,511,324 (1994) shows a shoe with a spring that is integrated within the heel section of the sole. Smith claims that due to the nature of his spring it will help be responsible for the decline in sports related injuries. Whether or not that is true, the simple fact remains that within Smith\'s embodiment there lie no springs to absorb the inevitable shock received by the arch, remaining midsection, and toe section of a user\'s foot. Also, as it is made clear within Smith\'s detailed description, there are an unnecessarily high amount of building requirements that make for additional costs, additional weight, and inefficiencies.

Young, in U.S. Pat. No. 1,380,879 (1921) has an invention relating to shoes that features springs. Initially noticed are the amount of particulars that constitute this shoe. To be specific there are at least 22 aspects to which many have become outdated and would now be unnecessary in related use. More importantly the vent openings located within the outer sole pose a threat in that outside elements may enter the shoe. These vents create the need for additional material to waterproof, which in time can deteriorate. Although there is minute airflow without vents, a shoe does tend to breath naturally, and a lack of additional vent will not form any pressure between an upper and lower portion. Additionally, as shown by the illustrations, the multitude of layers creates an affectively wider midsole, whereby the shoes upper must be taller to accommodate a users foot. Included within these mentioned layers as similarly used by Weisz, are metal plates—which add weight and generally are not suitable in the use of footwear. Finally, the additional springs placed beneath the arch of the foot in the uneven matter that they are employed presents possible pressure points that may induce pain upon the users foot.

Any shoe that has yet so far comprised of one or more springs, is known to suffer from a number of disadvantages:

(a) A multitude of components that make for the spring mechanism, cause the shoe to be heavy.

(b) Horizontally placed springs greatly limit the amount of spring action.

(c) Cost effectiveness is limited due to intricate design.

In conclusion, insofar as I am aware, no sandal formerly developed provides a spring bed underlying an upper portion and overlying a lower portion that supports and gives spring action for the heel, midsection, and toe portion of a users foot.

SUMMARY

In accordance with one embodiment a sandal comprises a foot strap, and spring means attached between an upper portion and a lower portion.

FIG. 1 is a right-side view showing various aspects of a sandal constructed in accordance with one embodiment.

FIG. 2 is a left-side view of the sandal of FIG. 1 with the springs being partially compressed by the weight of a user.

FIG. 3 is a perspective right side view of the sandal of FIG. 1 and shows indentations along the bottom side of an upper portion.

FIG. 4 shows a spring housing with hole.

FIG. 5 shows a spring housing with a spring threaded within hole.

FIG. 6 shows a rear lateral view of the sandal shown in FIGS. 1, 2, and 3.

FIG. 7 shows a rear lateral view with one larger spring in accordance with another embodiment.

FIG. 8 is a topside view of the lower portion showing attached springs.

FIG. 9 is a left side view of a sandal with a vamp style foot strap in accordance with another embodiment.

FIG. 10 is a left side view of a sandal with a slide style foot strap in accordance with another embodiment.

11 foot strap 12 top sole 13 upper portion 14 indentation 15 housing 16 hole 17 spring 18 lower portion 19 outer sole 20 user 21 vamp foot strap 22 slide foot strap

DETAILED DESCRIPTION

One embodiment of the sandal is illustrated in FIG. 1 (side view) and FIG. 3 (side view). The sandal has a foot strap 11 that is embedded within a top sole 12. The foot strap fits between a user\'s big toe and nearest toe. It is made of a loose nylon type material. A top sole 12 is rubber, but can consist of any other material that would be comfortable such as leather, plastic, nylon, vinyl, etc., and its dimensions as do the sandal vary upon size. An upper portion 13 is preferably one solid piece with top sole 12, but it can also be two separate pieces attached or unattached. Upper portion 13 is roughly 1 centimeter thick and consists of rubber, but can also consist of other materials that can provide as an upper portion with or without the same properties as rubber. Lower portion 18 is roughly 1 centimeter thick, and consists of the same material as upper portion 13. Underlying lower portion 18 is an outer sole 19 that is made suitable for outdoor and indoor elements. Both upper portion 13 and lower portion 18 are relatively flexible, but are stiff enough to adequately provide a proper support system for both springs 17 and user 20.

On the bottom side of upper portion 13 a means for showing predetermined locations, where housings 15 will be attached to, are a plurality of indentations 14. Indentations 14 are roughly 5 millimeters in depth, and are formed by means of transfer molding or compression molding. Housing 15 is a disc like apparatus that serves as a means for attachment; it is made from plastic, but can also be made from metal, wood, rubber, etc. It is approximately 2.5 centimeters in diameter and approximately 5 millimeters in height. Both sides of housing 15 are flat and the outward facing side has a hole 16. The springs 17 are an open coiled helical type made from metal and serve as the spring means. Springs 17 have an uncompressed height that is roughly 1.5 centimeters and a diameter that is roughly 1.5 centimeters. Within housing 15, space is provided, whereby the very end point of a coil from spring 17 is placed within hole 16 and turned in a screw like fashion so as spring 17 becomes securely fastened. The opposite end of the same spring is then fastened to an additional spring housing 15 in the same manner. Both sides of all springs 17 are fastened to all spring housings 15 prior to spring housings 15 being adhered to upper portion 13 and lower portion 18. A strong waterproof adhesive is then applied within indentations 14 located on lower portion 18. Spring housings 15 are then placed within indentations 14 and adhered, whereby when set will not become displaced. After all housings 15 with attached springs 17 have been adhered within indentations 14 upon the lower portion, the same adhesive is then placed within indentations 14 located on the bottom of upper portion 13. Upper portion 13 is then aligned to housings 15 and placed so as housings 15 are fit within indentations 14 on the bottom side of upper portion 13. Force is applied to ensure that a strong bond forms.

FIG. 6 shows a lateral rear side view of the sandal showing upper portion 13, and lower portion 18 with springs 17 arranged within the heel at their preferred but not necessary locations. FIG. 8 shows a topside view of lower portion 18 with springs 17 in communication with housings 15. Upper portion 13 is removed from drawing for viewing purposes.

The manner of using the sandal is identical to that for sandals in present use. Namely, a user 20 places foot strap 11 between their big toe and nearest toe. While standing, springs 17 compress thereby allowing upper portion 13 to descend towards lower portion 18. During use one walks in a normal fashion, however, the contraction and expansion proceeded by the spring action of spring elements 17 will be instantaneously noticed. FIG. 2 shows a left side view of the sandal with upper portion 13 and lower portion 18 drawn closer together by the weight of a user 20 causing springs 17 to compress. Note that compression of springs 17 and movement of upper portion 13 and lower portion 18 coincide. While walking the user can realize at least two immediate effects:

(1) Springs will contract producing a forgiving counter pressure allowing for a kinetic transfer of the users weight from heel to toe while providing a balanced and supportive bed.

(2) A new and exciting ease to walking as the spring action transfers from each section of the foot to another accordingly as the appropriate walking movements are taken.

(3) Extremely low impact levels as the sandal makes contact with the ground.

While the user is standing, the springs compress thereby drawing the upper portion nearer to the lower portion, creating a far more comfortable and forgiving stance than a sandal without springs.

Additional embodiments are shown in FIGS. 7, 9, and 10. In FIG. 7 the sandal has one larger spring with two smaller springs on either side. There are various possibilities with regard to the type of sandal and various types of foot straps as illustrated. FIG. 9 shows a side view of a vamp style sandal; FIG. 10 shows a slide style sandal.

There are various possibilities with regard to the characteristics of the upper portion, and lower portion. The upper portion and lower portion can be thicker or thinner, and can consist of any material that can provide comfortably in the use of footwear such as foam, wood, plastic, etc. The means in which the springs are attached to the upper and lower portions can be alternative to the degree in which there are no housings at all, whereby the springs are adhered directly to the upper and lower portion. In another instance, a similar connective device that may not be considered a housing, but rather an alternate means for connecting the springs can be used. The springs rather than being adhered can be integrated directly into the upper and lower portion, thereby becoming permanently bonded within. Also, the characteristics of the springs and their locations can vary. The springs can be attached from the outer sole to the upper portion rather than from the lower portion to the upper portion. There are various possibilities with regard to the type of springs used. They can vary from any type of compression spring—spring washer, and volute spring. The springs can be of different shapes, such as square springs, oval springs, triangular springs, etc. The springs can consist of different materials such as plastic, rubber, or any other material that can retain the defining properties of a spring. The springs can be greater in height or less in height, greater in diameter or less in diameter, they can also weigh less or more with the construction of a thicker diameter wire or thinner diameter wire, and the springs can have a higher spring rate or a lower spring rate. Also, the quantity of springs can substantially vary. The arrangement of springs and their relation to each other can vary to the extent of additional or less springs being arranged within the heel, midsection, or toe section of the sandal. There can be a combination of larger or smaller springs being used especially but not limited to the heel section. Also, the outer sole may consist of a different material than the lower portion.

From the description above, a number of advantages of some embodiments of my sandal with springs become evident:

(a) Rather than buying more expensive orthopedic footwear, a consumer will receive more impact alleviation and more comfort.

(b) The springs will not only serve as a completely functional upgrade, but they also enhance the dull and limited styling of sandals.

(c) Adults and children alike that walk on it will find the experience amusing yet practical, which serves as a great distinction from prior art.

(d) Although sandals are not considered ideal when walking longer distances. The design of my sandal will encourage people to rethink the limitations of a sandal, specifically to the aspect of suitability for walking long distances.

(e) With the adaptation of springs, the consumer will notice a feeling as if they were literally walking on a pocket of air.

(f) Springs in general are created in such volume that they are very cost effective for use. The consumer that is looking for inexpensive, comfortable, and functional footwear will find it with my sandal.

(g) The majority of consumers purchase sandals for the leisure aspect. With my sandal that is kept, with the addition of athletic traits.

(h) The design of a spring allows for an efficient and cost effective way to attach it to any footwear.

Accordingly, the reader will see that the sandal with springs of the various embodiments can be used as a more comfortable and functional form of footwear, and can be used just as practically yet much more excitingly than previous sandals. Several other advantages are to provide an improved sandal, to provide means of alleviating discomfort and pains from times spent on foot, to provide a more effective cushioning and support system, and to provide a more user friendly, yet economical sandal. Furthermore, the springs have the additional advantage in that: they permit the opportunity for allowing many more visual design cues due to the empty space that is created between the upper portion and lower portion; they themselves hold space for unique color variations.

Although the description above contains many specificities, these should not be construed as limiting the scope, but as merely providing illustrations of some of the presently preferred embodiments. For example, the foot strap may consist of leather, rubber, plastic, etc.; the bottom of the outer sole may have a more aggressive tread pattern; the space between the upper portion and lower portion may be enclosed within plastic, rubber, etc. Many other variations are possible.

Thus the scope of the embodiments should be determined by the appended claims and their legal equivalents, rather than by the examples given.