Athletic shoe having plug-in module

An athletic shoe (20) includes a sole (22), an upper (25), and a tongue (26), as well as fasteners (28), such as shoelaces. Incorporated into the sole (22) of the athletic shoe (20) is a receptacle (30) for receiving and retaining a plug-in module (32) in a slide-in, releasably locking arrangement. The plug-in module (32) preferably includes a battery (62), a light emitting device (54), and electrical circuit elements (58, 60, 72) arranged to selectively connect the battery (62) to the light emitting device (54).

BACKGROUND OF THE INVENTION 
The present invention relates to an athletic shoe having a novel feature 
directed to enhancing its safety and practical utility. More specifically, 
the athletic shoe of the present invention incorporates a releasably 
locking, plug-in module that is removably insertable into a recessed 
retaining receptacle in the sole of the shoe. The plug-in module may 
include a battery and an externally visible light emitting device 
interconnected via circuitry that includes a switch for energizing the 
light emitting device in response to pressure exerted upon it by the foot 
of the wearer during walking or running. 
There are a number of references in the patent literature that depict 
various methods for incorporating light emitting elements and batteries to 
energize them into various portions of a shod in order, e.g., to provide a 
visually distinctive shoe. In a majority of the examples found in the 
prior art, the light emitting device, as well as the batteries, have been 
incorporated into the heel portion of the sole of a dress shoe. The 
advantage of this configuration is that the heel of a dress shoe generally 
provides sufficient volume to easily accommodate the electronic apparatus, 
and is constructed of a rugged, non-resilient material that protects the 
light and battery and, in a translucent version, can also serve as a light 
conductor or spreader. 
For example, U.S. Pat. No. 4,253,253, British Patent No. 444,392, and 
Belgian Patent No. 570614, all illustrate womens high heel dress shoes 
incorporating a battery in the hollow interior of the heel of the shoe. 
Alternatively, U.S. Pat. Nos. 1,597,823, 2,931,893, 4,014,115, and 
5,052,131, as well as European Patent publication No. EP-121-026-A, depict 
lighted dress and casual shoes incorporating a raised or block-type of 
heel having a recessed inner portion for receiving the battery. 
There may be several reasons for incorporating an active light emitting 
device into a shoe, e.g., to enhance the night safety of the wearer, to 
provide special visual effects at entertainment events, or to assist in 
certain biomechanical testing and measurements. 
Thus, while it is known to incorporate passive reflectors, including 
reflective tapes and the like, on the equipment or apparel of athletes, 
such as joggers or bicyclers to increase their visibility, and hence, 
safety, at night, it is necessary for the purely reflective elements to be 
illuminated by an external, active light source, such as the beam of an 
automobile headlight, in order for them to function. Footwear that 
incorporates its own built-in, active light source, and which, therefore, 
does not depend on an external source for illumination, can provide a 
higher level of visibility and safety than those that are purely 
reflective in nature. 
Further, the incorporation of active light sources into the shoes of 
participants engaged in certain entertainment events, such as those worn 
by dancers, marching bands, athletes and the like, can achieve special, 
entertaining visual effects in low light conditions, particularly where it 
is desired to call attention to the participants' feet. For example, a 
marching band equipped with such footwear can present an impressive 
spectacle, as the individually-illuminated feet of its members move in 
synchronous unison. 
The provision of an active light source on the shoes worn by test subjects 
engaged in certain walking and running motion studies can also enhance the 
ability of scientists and biomechanical engineers to measure and analyze 
those activities from a human engineering or sports medicine standpoint. 
Such studies frequently involve photographing a particular point or 
reflective target disposed on the foot or ankle of a test subject with 
high-speed motion picture equipment, then digitizing the motion of that 
point for subsequent analysis with a digital computer. The incorporation 
of an active point light source on the shoe at the point under examination 
can enhance the testing procedure because the active light source is 
photographically more distinct, and hence, easier to photograph. 
Additionally, the light source can be adapted with a pressure- or 
acceleration-sensitive switch to illuminate selectively when a certain 
preset force or acceleration is exerted upon it during a particular 
activity. Thereby, the forces or accelerations acting on the shoe during 
various athletic endeavors can be better analyzed. 
A review of the references in the prior art reveals that the incorporation 
of a light-emitting device into the sole of an athletic shoe is 
complicated by the specific qualities of resiliency, flexibility, and 
support required of such a shoe's sole during athletic activities. An 
improperly designed athletic shoe sole that does not provide the desired 
degree of support, protection, and comfort for the athlete is 
unacceptable. Thus, it is not a simple matter of taking the teachings of 
the prior art, directed to various types of dress and casual shoes having 
block or high heels and essentially rigid soles, and incorporating the 
designs for their lighting device and power sources in generally the same 
configuration into an athletic shoe. 
A further limitation of the designs of the prior art, to the extent that 
they can be incorporated into athletic shoes, relates to their relative 
inaccessibility within the shoe, with a concomittant lack of 
replaceability and maintainability of their various components, including 
their batteries, light sources, and switching components. 
SUMMARY OF THE INVENTION 
This invention discloses an article of athletic footwear of relatively 
conventional construction, but which incorporates into its sole a 
receptacle that is configured to receive a removable, plug-in module in 
slide-in, releasably locking engagement. The module preferably includes a 
replaceable power source, e.g., a battery, electrical circuitry that 
includes a switch, for example, a pressure sensitive switch that is 
operatively responsive to a force exerted on it by the wearer's foot, and 
a light-emitting device, such as a light emitting diode ("LED"). The 
plug-in module is configured to be inserted into the receptacle in 
slide-in fashion, and positively, although removably, retained therein. By 
this configuration, the plug-in module can be easily removed from the 
athletic shoe, to allow, for example, replacement of the battery, or to 
allow replacement of the entire plug-in module with another module having, 
for example, a different light source, power supply, mode of operation, or 
even an altogether different function.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates an athletic shoe 20 according to the present invention. 
The shoe 20 typically includes a resilient sole 22, which may itself 
further comprise a midsole portion 23 and an outsole portion 24 underlying 
it, as well as an upper 25, a tongue 26, and fastener means 28, such as 
the laces illustrated, for securing the shoe to the wearer's foot. 
As illustrated in greater detail in FIGS. 2 and 3, incorporated into the 
sole 22 of the athletic shoe 20 are receptacle means 30 for receiving and 
retaining a plug-in module 32 in a slide-in, releasably locking 
configuration. The receptacle means 30 are preferably disposed in the heel 
portion 36 of the sole 22, where the sole is typically the thickest, and 
comprise an opening 40 into, and an internal chamber 42 within, the 
midsole portion 23 of the sole of the shoe, for allowing insertion, 
retention, and removal of the plug-in module 32. 
As may be appreciated from FIG. 2, the receptacle means 30 also preferably 
include a more rigid, rectangular tray structure that is molded or bonded 
into the midsole portion 23 of the sole 22 of the shoe. The internal faces 
of the side walls 43 defining the tray structure of the receptacle means 
30 include a pair of depressions 44, the operative function of which is 
described below. 
The plug-in module 32 includes a structure that can be likened to a small 
cabinet drawer. The plug-in module 32 includes a housing or body 46 having 
an outer face 50 and a generally rectangular body portion 52 that is 
configured to be slidably inserted into the interior of the receptacle 
means 30. Affixed to, or formed as a part of the lateral side walls of the 
rectangular portion is a pair of protrusions 48. These protrusions 48 are 
configured to engage the depressions 44 in the walls 43 of the receptacle 
means 30 in a resilient, camming, over-center, locking engagement upon 
complete insertion of the plug-in module 32 into the receptacle means 30, 
thereby releasably locking and retaining the plug-in module 32 therein. 
This releasable locking arrangement prevents inadvertent ejection of the 
plug-in module 30 from the shoe during vibration, flexure or shock of the 
shoe, but can be overcome by the user in the manner described below. 
The plug-in module 32 is also preferably configured to include a pair of 
tabs 66 at the edges of the outer face 50. The tabs 66 are formed to fit 
smoothly within a pair of scallops or contoured recesses 68 formed into 
the outer surface of the sole 22 immediately adjacent the sides of the 
opening 40, without exposing any sharp corners,. By this co-operative 
relationship, the scalloped-shaped recesses 68 permit the wearer of the 
shoe 20 conveniently to grasp the tabs 66 of the plug-in module 32 with 
his or her fingertips and, by pulling forcefully outward on it, overcome 
the resilient locking engagement of the module side protrusions 48 within 
their mating receptacle depressions 44, thereby permitting extraction of 
the plug-in module 32 from the receptacle means 30. 
In the embodiment illustrated in FIGS. 2-7, the plug-in module 32 
preferably includes a light-emitting device, such as a light bulb or a 
light-emitting diode ("LED") 54 molded, bonded, or otherwise fixed into a 
bore or aperture 55 that extends through the outer face 50 and into the 
body 46 of the module 32, such that the bulb or LED 54 is visible to the 
exterior of the shoe when the module is plugged in. Desirably, the LED 54 
is selectably connectable via electrical contacts and circuit elements 58, 
60 to a battery 62 disposed within the inwardly-projecting rectangular 
portion 52 of the plug-in module 32, as shown in FIGS. 4 and 5. 
The plug-in module 32, or alternatively, the receptacle means 30, the sole 
22 or the midsole portion 23 may further incorporate a raised, or 
depressed portion 70, respectively, that is intended to engage and 
activate a simple pressure-sensitive switch 72 disposed on the top of the 
plug-in module 32 for completing the electrical connection of the battery 
62 with the LED 54, as described in more detail below. 
FIG. 6 is a cross-sectional view taken along line 6--6 in FIG. 4, and 
illustrates the electrical elements of the plug-in module 32 in more 
detail. More particularly, it will be seen that the battery 62, which may 
be a relatively small, disk-shaped, 3-volt lithium battery, may be 
positioned and retained by its edges in the body 46 of the module 32 in 
the orientation shown, i.e., with its oppositely-charged electrical 
terminals facing upwardly and downwardly, respectively, by means of a pair 
of spaced, opposing slots 63 formed into the interior side walls of the 
module body 46, into which the battery is snapped or slid. The circuit 
elements 58 and 60 may consist of nothing more than the stock wire leads 
with which the LED 54 is typically furnished at the factory. In the 
embodiment illustrated, these are brought through the aperture 55 into the 
interior of the body 46 to straddle the battery 62 in the manner shown. 
As will be appreciated, for a simple LED-battery circuit, all that is 
required to complete the circuit is to bring appropriate ones of the LED 
leads 58, 60 into simultaneous contact with respective ones of the 
terminals of the battery 62, which, in the exemplary embodiment 
illustrated, is accomplished without need for any soldering or elaborate 
electromechanical contacts as follows: The lower one 60 of the LED leads 
is brought forward along the upper surface of the floor, or bottom wall, 
of the body 46 of the module 32 until it underlies the battery 62. The 
lead 60 may be fixed in this position by bending its free end downwardly, 
feeding it through a small aperture 64 in the floor of the body 46, then 
nipping it off flush with the underside of the body, but this latter 
refinement is not necessary to the desired result: The LED lead 60 is 
sized, and the position of the battery 62 is controlled such that, when 
the battery is snapped or slid into place in the module, its lower 
surface, comprising one of its electrical terminals, is maintained in 
constant electrical contact with the lead 60. 
A similar arrangement may be adopted with the upper lead 58 of the LED, 
except that, here, it is brought forward along the lower surface of a 
cantilevered arm 74 extending forwardly from the upper surface of the body 
46 of the module 32 to overlay the battery 62 and its second, 
upwardly-facing electrical terminal (see FIG. 3). If desired, the lead 58 
may be fixed in a manner similar to that described above by bending its 
loose end upwardly and feeding it through a small aperture 65 through the 
arm 74, then terminating it flush with the body 46, but again, it has been 
found that this is unnecessary to the resulting switching function. 
Indeed, in a more elaborate version, the upper surface of the floor of the 
module 32 and the lower surface of the arm 74, respectively, may each be 
provided with an electrical contact to which respective ones of the LED 
leads are soldered or crimped, the contacts being disposed appropriately 
with respect to the battery to contact respective ones of the battery's 
terminals under the appropriate conditions. However, as indicated above, 
these additional components and connections can result in an increased 
cost for the module without an attendant gain in reliability of function. 
The position of the arm 74 can be adjusted such that, in one configuration, 
each of the leads 58, 60 of the LED are in simultaneous electrical contact 
with respective ones of the battery terminals whenever the battery is slid 
or snapped into place in the module 32. In this configuration, the LED is 
continuously "ON" whenever the battery 62 is installed in the module 32, 
regardless of whether the module 32 is plugged into the receptacle means 
30 or not. 
Alternatively, and more preferably, the position of the cantilevered arm 74 
can be adjusted such that the upper lead 58 is spaced slightly apart from 
the upper terminal of the battery 62. In this embodiment, the circuit is 
"open", and the LED "OFF", until the arm 74 is forced downwardly such that 
the upper lead 58 makes forceful contact with the upper terminal of the 
battery, thereby completing the circuit and switching the LED "ON". In one 
embodiment, this may be accomplished by simply plugging the module 32 into 
the receptacle means 30, provided that the arm 74 is positioned 
appropriately relative to the upper, interior surface of the receptacle 
means 30 so that the former is forced downwardly by the latter when the 
module 32 is plugged into the receptacle means 30. In this embodiment, the 
LED is switched "ON" whenever the module 32 is plugged into the shoe 20, 
and "OFF" when the module is withdrawn. 
In yet another embodiment, as illustrated in FIG. 7, the arm 74 can be 
disposed, relative to the upper, interior surface of the receptacle means 
30, to require the wearer of the athletic shoe 20 to exert an additional, 
downward force or pressure on the arm 74, through the agency of a layer of 
the midsole 23 overlying it, such as that exerted on it by the heel of the 
wearer's foot during walking or running, in order to perfect the 
electrical contact of the lead 58 and energize the LED 54. Thus, it will 
be seen that, in this arrangement, the arm 74 functions as a simple, 
inexpensive, but effective means for implementing the pressure-sensitive 
switch 72 discussed above, and the athletic shoe 20 may thereby be 
equipped with a pressure sensitive light emitting device. 
FIG. 8 illustrates an exploded view of the receptacle means 30 and plug-in 
module 32 of FIG. 1. The plug-in module 32 is preferably configured to be 
insertable into the receptacle means 30 in either a right-side-up 
orientation, as seen in FIG. 2, or an inverted orientation, as shown in 
FIG. 8. By this arrangement, the position of switch 72 or arm 74, or 
alternatively, the upper and lower internal surfaces of the receptacle 
means 30, can be configured, relative to each other, such that the module 
is in the always-"ON" mode, or alternatively, in the mode that is "ON" in 
response to foot pressure, both described above, whenever the plug-in 
module 32 is inserted in the receptacle means 30 in the right-side-up 
orientation, and always "OFF" otherwise. 
This embodiment permits the plug-in module 32 to be removed from the shoe 
20 by the user, turned over, and re-inserted into the receptacle means 30 
without the LED 54 being energized, or alternatively, without the switch 
72 being operationally responsive to foot pressure to switch the LED "ON", 
even when the module 32 is plugged in and pressure is being exerted on the 
module by the wearer's foot. Thus, when the wearer of the athletic shoe 
does not wish to have the light "ON", or alternatively, "ON"-responsive to 
foot pressure, he or she may simply remove the plug-in module 32 and 
reinsert it back into the receptacle means 30 in the inverted position. 
This permits the module 32 to be lockingly retained in the shoe 20, but in 
the always-"OFF" mode, and thereby prevents the likelihood that the 
plug-in module 32 might become separated from the shoe and lost. 
For an athletic shoe, it is important to appreciate that the midsole 
portion 23 of the sole 22 frequently is formed from a molded piece of 
foamed elastomeric material, such as ethylene vinyl acetate ("EVA") or 
polyurethane ("PU"), whereas, the outsole 24 is typically a harder, 
non-foamed elastic material, such as synthetic rubber. These structures, 
acting in cooperation with each other and the remaining elements of the 
shoe, are required to provide resilient support of all of the structural 
elements of the foot, and in particular, the heel bones and the bones of 
the balls and toes of the foot, which take the brunt of impact shock 
during any particular athletic activity that involves running or jumping. 
Indeed, the sole 22 is required to absorb and recoil from impact and 
shock, yet be sufficiently flexible to allow the flexure and return 
required by the heel-to-toe progression that occurs during walking or 
running, and also to absorb lateral forces resulting from the various 
types of rotational motion that may be imparted by the wearer during 
various other kinds of athletic activities. 
Accordingly, it will be understood that the resilient support nature of the 
sole 22, particularly the midsole portion 23 of the athletic shoe 20, must 
adhere to particular design constraints, even though it may also be 
desirable to incorporate within it a plug-in module arrangement of the 
type described herein. 
In the cross sectional view of FIG. 4, the receptacle means 30 are 
illustrated as being spaced between top and bottom layers of the midsole 
portion 23 of the sole 22. More particularly, for a midsole 23 having a 
base thickness D.sub.1, and wherein the thickness of the receptacle means 
is T.sub.1, the thickness of the resilient portion of the midsole 23 above 
the receptacle means 30 will be D.sub.2, and the thickness of the 
resilient midsole element below the receptacle means 30 will be D.sub.3. 
It has been discovered that, for a midsole having typical hardness 
characteristics and a thickness of D.sub.1 in the range of between 15 and 
22 millimeters, the ratio of D.sub.2 to D.sub.1 will preferably be in the 
range of between about 0.09 and 0.2 to achieve successful incorporation of 
a plug-in module of the general type described herein within the midsole, 
yet retain the desired athletic shoe sole shock and flexibility 
characteristics. Further, the preferred ratio of D.sub.3 to D.sub.1 will 
be in the range of between about 0.2 and 0.5, and the ratio of the 
thickness T.sub.1 of the receptacle means to the thickness of the sole 
D.sub.1 will preferably be in the range of between about 0.45 and 0.8. 
FIG. 5 illustrates a cross-sectional view taken along line 5--5 of FIG. 4. 
In FIG. 5, the outer portion of the receptacle means 30 is illustrated, as 
is the cross-section through the plug-in module 32 depicting the LED 54 in 
the center thereof. In addition, the relative thickness of the material of 
the midsole in the space above the plug-in module 32 is again illustrated. 
For purposes of maintaining the proper distance, this thickness of the 
midsole should preferably be in the range of 2 to 5 millimeters for 
elastomeric materials having a hardness of about 55 to 60 Shore-C. 
However, it should not be presumed from the preceding discussion that the 
plug-in module 32 of the present invention is necessarily limited to 
athletic shoes having separate, layered midsoles and outsoles of solid or 
foamed resilient materials, as described above. FIG. 9 illustrates an 
alternative form of sole construction for an athletic shoe that is 
frequently referred to as a "cupsole unit bottom" 75. Here, the outsole 
element 24 of the shoe is typically molded of a resilient rubber material 
to include an upwardly-wrapping sidewall 76 that defines an 
upwardly-facing "cup" 77, into which the upper 24 of the shoe is received 
and fastened. 
In such construction, it is possible to include a conventional midsole 
structure, either in a premolded, drop-in form, or by directly molding it 
therein, prior to attachment of the upper. Alternatively, and usually as a 
cost- and/or weight-saving feature, the midsole may be omitted altogether 
in preference to the "bridgework" type of structure illustrated, 
comprising a plurality of upstanding, interconnected walls 78 that are 
integrally molded into the cupsole structure, and which define between 
them a plurality of open-topped, unconnected, hollow cavities. These 
cavities are subsequently "closed" when the upper is bonded into the cup, 
which typically involves the placement and bonding of a "lasting board", 
incorporated into the bottom of the upper, onto the upper surface of the 
cavities. 
As will be seen, this alternative form of sole construction can easily 
accomodate the plug-in module 32 of the present invention, provided 
certain provisions are made to accomodate it. Thus, in the bridgework-type 
of cupsole construction illustrated in FIG. 9, a cavity 42A that conforms 
to the outer length and width dimensions of the receptacle means 30 is 
formed into the cupsole 75 at the time of its initial molding. The 
upstanding sidewall 76 includes an opening 40 extending through it and 
into the cavity 42A, similar to that found in the midsole-equipped shoe of 
FIG. 2. 
The height C.sub.1 of the cavity 42A, however, exceeds the thickness 
T.sub.1 of the receptacle means 30, and is typically on the order of about 
12-18 millimeters (mm). Accordingly, to accomodate this difference in 
dimensions, and to ensure functional equivalency with the resilient 
midsole-equipped shoe having a plug-in module of the type discussed above, 
top and bottom die-cut, resiliant foam inserts 79A and 79B having a 
hardness in the range discussed above in connection with foamed midsole 
materials are disposed above and below the receptacle means 30, 
respectively, within the cavity 42A to form a layered sandwich therein. 
The layers of the sandwich are then adhesively bonded to each other and to 
the sidewalls and floor of the cavity to hold the receptacle means 30 in 
place. 
To arrive at the appropriate thicknesses and C.sub.2 and C.sub.3 of the top 
and bottom inserts 79A and 79B, respectively, it is necessary first to 
subtract the thickness T.sub.1 of the receptacle means 30 from the height 
C.sub.1 of the cavity 42A. The difference is then preferably apportioned 
between C.sub.2 and C.sub.3 in the ratio of 60% to 40%. Thus, in a 
preferred embodiment, and where the cavity height C.sub.1 is about 12-18 
mm, the thickness C.sub.2 of the top insert 79A will be about 2-4 mm, and 
the thickness C.sub.3 of the bottom insert 79B will measure about 1-3 mm, 
all other things remaining the same. Likewise, the ratio of C.sub.2 to 
C.sub.1 will preferably be in the range of about 0.11-0.33, and the ratio 
of C.sub.3 to C.sub.1 will be about 0.05-0.25. 
Our tests have shown that, provided these guidelines are adhered to, there 
is essentially no difference in plug-in module implementation and 
performance between shoes equipped with solid, layered midsoles, such as 
that illustrated in FIG. 2, and those equipped with open-bridgework 
cupsoles, as illustrated in FIG. 9. Indeed, the plug-in modules are 
completely interchangeable between the two in terms of form, fit and 
function. 
The components of the receptacle means 30, as well as the plug-in module 
32, are preferably formed from an inexpensive, yet durable plastic 
material, such as an acetyl resin for colored parts, or a polycarbonate 
for clear parts. These materials provide adequate rigidity and durability, 
yet are sufficiently resilient to permit the spring-like flexure of, for 
example, the complementary locking engagement means 44, 48 and the 
cantilevered switch arm 74 features discussed above, and also conform well 
to the rigors of the intended environment. 
FIG. 10 depicts an alternative embodiment of a plug-in module 80 having a 
different function than that described above. The module 80 is generally 
sized the same as the plug-in module 32 of FIGS. 1-7; however, in this 
embodiment, the circuit elements, such as a battery or an LED, are 
omitted. Instead, the module 80 is adapted to provide a small, personal 
storage compartment 82 having an open top, and optionally, a retaining 
clip 84 in its internal recess 86. The compartment 82 is closed when the 
module is plugged into the shoe 20, and by this arrangement, as opposed to 
the lighting function of the plug-in module 32, functions as a small, 
portable, enclosed storage compartment for take-along storage of small 
personal articles of the wearer, such as money, or a locker or house key. 
FIG. 11 depicts an alternative configuration of the present invention, in 
which an athletic shoe 102 includes the receptacle means 30 and plug-in 
module 32 generally equivalent to that seen in FIGS. 1-7, and 
additionally, a plurality of LED's 104, 106, 108 spaced about and 
incorporated into the sole 22 of the shoe. The plurality of LEDs are 
connected via electrical conductors 110 to a point proximate the 
electrical conductors or circuit elements 58, 60 of the plug-in module 32 
by, for example, simple contacts on the top and bottom or on the sides of 
the plug-in module. By this configuration, the benefits of being able 
quickly to remove and replace the battery in the plug-in module, and the 
attendant design advantages thereof, can be utilized for powering a number 
of LEDS spaced remotely about the shoe 102. Further, if desired, the LEDs 
could be spaced at various locations other than in the sole 22 of the shoe 
102 and interconnected via electrical conductors to the plug-in module 32. 
Indeed, the skilled practitioner will by now recognize that many variations 
and modifications of the plug-in module for an athletic shoe described 
herein are possible in terms of function, materials, configuration, and 
mode of operation, depending on the particular problem at hand. 
Accordingly, the embodiments described herein should be taken as exemplary 
in nature only, and the scope of the present invention limited only by the 
proper interpretation of the claims appended hereafter.