Description of Related Art Recently, demand of so-called walking or sports shoes has increased, for daily use as town shoes as well as for walking or sports. Various shoes provided with cushions or shock-absorbing structures which can absorb shock applied on the sole of the shoe have been developed and put on the market.

Further, these shoes have been manufactured in accordance with fashion and well accepted by younger generation. Thus, large variety of such shoes are now on the market.

Until now, however, we can find only shoes provided with a simple shock- absorbing structure, for example, an isolated chamber filled with elastic foamed materials having low impact strength or an air-compressed balloon.

On the other hand, there is no proposal of any shoes being able to avoid adverse influence of human health due to static electricity generated and accumulated in human bodies during any motion with shoes on.

The present inventors have paid their attention to generation and accumulation of static electricity in human bodies caused by motion with inadequate shoes on and considered its adverse influence to health.

Most of people have such experience that they get a shock when touched a door knob with their fingers, particularly on a dry day in winter. This is caused by instant discharge of static electricity accumulated in a human body.

It is well known that static electricity is generated when two different materials are rubbed each other. That is, electrons are released from one of the materials into the others when those materials are rubbed each other by friction energy. As the result, one material lost electrons is charged in positive and the other gained electrons is charged in negative. Static electricity thus generated can be discharged any time if the material is electro-conductive. In case the material is not electro-conductive, static electricity is accumulated to produce high voltage. For example, it is said that the voltage of static electricity accumulated in a human body easily reached to from several thousands to several ten thousand volts. When static electricity of such a high voltage instantaneously discharges out of a human body, he must get a shock.

Actually, at a hospital, discharge of static electricity generated and accumulated in doctors'or nurses'bodies radiates electromagnetic wave which causes disorder or trouble with various equipment for medical examinations and treatments in use, or medical devices such as a pacemaker built in a patient's body. In order to avoid such troubles or damages, electro-conductive floor has been introduced in the hospital, but these problems are not yet completely solved.

Further, it has gradually been clarified that static electricity generated by friction between two different materials exerts adverse influence on physiological activity of human being. For example, it is reported that static electricity accumulated in a human body may destroy Vitamin C, consume calcium, promote formation of melanin in a body. It is also a trouble that such static electricity spoils the harmony of biochemical reactions with physiological electric reactions, and then may upset physiological activity of human bodies.

Human beings are different from other mammalians at the point of being unable to synthesize Vitamin C in their bodies. Therefore, they have to take Vitamin C from various foods. Exhaustion of Vitamin C due to static electricity reduces Vitamin C in a human body, which causes various physiological disorder. Acute reduction of Vitamin C causes functional disorder of human bodies, for example, circulatory disease such as heart attack or nervous disease such as convulsion or stiffness of muscles. The required quantity of Vitamin C increases along with the degree of stress being imposed to human being. Accordingly decrease in Vitamin C rises stress and causes worse fatigue. Further stress leads to promote secretion of adrenaline which relieves stress. Lack of Vitamin C accumulates stress and increases fatigue, because Vitamin C has a function of promoting adrenaline secretion. In addition, Vitamin C relates to formation of collagen which links cells together. It means that consumption of Vitamin C decreases collagen, spoils good mental tension and quick actions and results fatigue and ennui as well.

It is also reported that consumption of calcium via exhaustion of Vitamin C being caused by accumulation of static electricity in human bodies obstacles various enzyme systems and nervous transmission systems, and causes convulsion and stiffness of muscles. Exhaustion of calcium causes oxidized decomposition of collagen which links cells together at muscles and skins.

Thus coarse and loosen skin is resulted, and this phenomenon means aging of physiological reactions itself. Moreover there are electrical and chemical information transmission system among nervous and muscle cells within a human body, and calcium contributes to all of its transmission system.

Therefore it is easily imagined that such mechanism of signal transmission is affected to some considerable extent by accumulation and sudden discharge of static electricity in human bodies. As mentioned in detail above, static electricity accumulated by long lasting or repeated motion affects adversely to physiological activities and then causes bad accumulation of fatigue and delay in recovering out of fatigue.

SUMMERY OF THE INVENTION The purpose of the present invention is to provide a shoe being capable of discharging statistic electricity which is generated and accumulated in human bodies during walking, moving, running or working, so that any of adverse influence on human health caused by static electricity can be avoided.

BRIEF DESCRIPTION OF DRAWING Fig. 1 is a plan view of a sole in accordance with one embodiment of the present invention.

Fig. 2 is a cross-sectional view in A-A line of the sole shown in Fig. 1.

Fig. 3 is a cross-sectional view in B-B line of the sole shown in Fig. 1 DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The shoes provided in accordance with the present invention have an electro-conductive in-sole, which contact with feet, and an out-sole which are electrically connected with the in-sole and has a grounding area. The shoes of the present invention may include rain shoes, lace-up boots, sports-shoes, overshoes, working shoes, nurse shoes, fishing boots, short boots, long boots, half boots, lady's shoes, arctic boots or shoes, and baby boots, etc. As sports-shoes, golf shoes, soccer shoes, gymnastic shoes, mountain-climbing boots, basketball boots, handball boots, bowling shoes, boxing boots, rugby boots, athletic shoes, etc. may be included. The present invention is effective particularly to sports-shoes, working shoes, nurse shoes, or lady's shoes, wearers of which are affected to a considerable extent by static electricity.

The working shoes of the present invention are particularly suitable for use at such working areas that human bodies are easily affected by static electricity accumulated therein, e. g., chemical plants or fuel service yards where combustibles are handled, chemical institutes or research laboratories, gas stations or hospitals, etc.

The shoes of the present invention prevent fatigue brought by accumulated static electricity or injury caused by sudden discharge of such static electricity. For instance, athletes or players who put on the sports-shoes of the present invention can be prevented from being fatigued and can have enough endurance to make good records.

In general, a sole of shoes is composed of an in-sole just under a foot, an out-sole which contact with ground and a mid-sole between the in-sole and the out-sole. The in-sole of the shoes of the present invention have at least a function to transfer static electricity generated in a human body during walking or running to the grounding area of the out-sole. The position where feet contact with the shoes can be its inner surface including the in- sole.

The in-sole of the shoes of the present invention which directly contacts with a foot has an electro-conductive part, which may be partially or wholly made of a electro-conductive material.

The electro-conductive part can be made from whatever materials which is able to lead static electricity being accumulated in human body during walking or running toward the grounding area of the out-sole.

As the electro-conductive material, may be included aluminum, copper and combination of them, carbon materials such as carbon fibers, carbon black and combination of them. Such materials can be in a form of powder, fiber, sheet, film, mesh, fabric, non-woven fabric, mixed woven fabric, etc.

In case the electro-conductive material is made in a form of powder or fiber, the powder and/or fiber may preferably be dispersed in a synthetic resin as a matrix. It is preferable to prepare whole of the in-sole with such a matrix composition. In summery, whole or only a part of the in-sole, which contacts with a foot, can be prepared with a matrix composition containing electro- conductive materials. Furthermore, the in-sole may be wholly or partially covered with elector-conductive materials including metal vapor deposited film.

The position on the in-sole where electro-conductive materials are located is not necessarily limited, but may be on stepping area or heel of sole depending on the kind of sports. This position should be selected from the points where it get a strong impact at every step in order to make grounding effect better.

In the present invention, the sole of shoes should be grounded at least one part every time when it contacts with the ground. The out-sole is connected with the in-sole with electro-conductive material, so that static electricity on the in-sole can be discharged to the ground through the grounding area of the out-sole. That is, the electro-conductive part of the in-sole is connected to the ground via the electro-conductive part of the in-sole and the grounding area of the out-sole, so that static electricity accumulated in a human body can be discharged.

In the embodiment of the present invention, the same electro-conductive material as used for the in-sole may be used for the grounding area of the out-sole. And of course, a different electro-conductive material than the material used for the in-sole may be used for the grounding area of the out-sole and both may be connected each other with an electro-conductive means. The position on the out-sole where an electro- conductive area is located is not particularly limited.

The embodiment of the shoe of the present invention will be illustrated below with reference to some drawings. The present invention should not be limited to the embodiment illustrated herein, but may be modified within the spirit of the present invention.

Example As shown in Fig. 1~3, sole 7 of a shoe consists of three layer parts of in-sole 1, mid-sole (or middle sole) 2 and out-sole 3. The inside of the in-sole 1, where a foot contact with, is composed of an electro-conductive sheet 4, using a mesh made of fine yarns derived from an aluminum vapor deposited film.

The sheet 4 is arranged to be electrically connected to the electro-conductive block in the grounding area of a opening 6 via a slit 5 provided at the mid-sole 2. Instep and vamp 8 is built up from edges of the sole so that it can wrap a foot in.

The out-sole 3 has the opening 6 on its stepping area and the opening 6 is filled with an electro-conductive plastic block containing dispersed copper powder. In other words, the out-sole 3 is comprised of a part being grounded directly to earth and a copper-dispersed plastic block inserted into the opening 6 provided at the stepping area of the out-sole 3.

When one walks or run with thus obtained shoes, static electricity being generated and accumulated in his or her body can be conducted to the out- sole 3 through the electro-conductive part of the in-sole 1, regardless of whether his feet were naked or in socks. Then static electricity may be transferred from the in-sole 1 to the electro-conductive block of the out-sole 3, and finally be discharged out to the ground.

Thus, the shoes of the present invention can completely discharge static electricity being accumulated in human bodies during walking or running to the ground, and therefore have no adverse influence on human bodies such as destroy of Vitamin C or reduce in calcium or collagen in human bodies.