Abstract:
An apparatus and method for measuring a plantar contour having a foam impression block and a carrier. The apparatus has a foam impression block including a front portion and a rear portion and a carrier including a height adjuster. The block is associated with the carrier such that the rear portion and the height adjuster are adjacent one another.

Description:
RELATED APPLICATION 
     This application claims priority of U.S. Provisional Application No. 60/164,090, filed on Nov. 6, 1999, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method of use for measuring the geometry of a foot in the position the foot will be in when inside of a shoe. More particularly, the present invention relates to an apparatus having a foam impression block specially formed into the shape the target foot wear will have. Moreover, the present invention relates to methods of using such an apparatus for measuring the plantar contour and instep of a foot in the position the foot will be in when inside of a shoe. 
     2. Description of the Related Art 
     A number of methods currently exist to measure the geometry of the plantar contour of a foot. The accurate measurement of the plantar contour is used in the manufacture of custom insoles. The prior art methods include plaster casting, optical scanning, contact sensor measurement, as well as foam impression measurement. These methods require the foot to be in a planar position. However, some shoes, such as high heels or other shoes with a slope, distort the plantar contour and instep due to the shifting of the user&#39;s body weight. Accordingly, the insoles made using these prior art methods do not account for such distortions. Moreover, these prior art methods are not well suited for home use. 
     The optical scanning methods and contact sensor measurement methods utilize expensive equipment. These methods provide an accurate and complete measurement of the foot. But, the size, expense and complexity of the equipment necessary for these methods makes them not suitable for use in all locations. Moreover, these methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe. 
     Plaster casting methods require the measurement to be performed by a person other then the one being measured. This method provides an accurate and complete measurement of the foot but can be very messy and time consuming. Thus, plaster casting methods are not suitable for use in a person&#39;s home or by one&#39;s self. Moreover, these methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe. 
     Foam impression measurement methods and apparatus utilize an easily deformable foam block. A person steps onto the block, thus crushing the foam in the locations of higher pressure. In this manner, the foam block deforms in the approximate shape of the persons&#39; plantar contour. While this prior art method may be suitable for home use, it produces a sub-optimal characterization of the foot for a number of reasons. First, the foam block is uniform in thickness from heel to toe. This causes the toes to be forced upward as the foot is pressed into the foam because the toes of the foot have substantially less pressure on them than the region of the foot from the heel to the metatarsal heads. Forcing the toes upward can cause a number of problems including, hyper-extension of the plantar fascia, lowering of the correct arch height, and improper measurement of the forefoot and heel. Second, under full body weight, the foot expands allowing for a larger than normal foot impression. Additionally, the prior art does not provide for measurement of the instep. Moreover, the current foam materials and methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe. 
     In the manufacture of custom insoles, the use of the plaster casting and foam impression methods also require the use of a scanning system. The scanning system may act directly on the negative impression within the foam or plaster. Scanning systems that act directly on negative impressions are known in the art. These laser scanning systems consist of a laser with a line generating optic. The laser projects a line at a know incident angle onto the negative impression. A camera is used to read the position of the laser line on the negative impression. Alternatively, the scanning system may act on a positive plaster model made from the negative impression within the plaster or foam. Scanning systems that act directly on the positive impressions are also known in the art. One such scanning system, provided by U.S. Pat. No. 4,876,758, specially constructed array of pin-like sensors. In either circumstance, the scanning system is used to digitize the measured contour. The digitized contour is provided to a computer controlled milling machine. The milling machine uses the digitized information to manufacturing a custom insole matching the digitized contour. Accordingly, the apparatus and methods of the present invention provide for cheaper and easier means to provide custom manufactured insoles to a customer. 
     Accordingly, it is an object of the present invention to provide foot measurement apparatus and methods, which overcome the limitations set forth above. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an apparatus for measuring a plantar contour. The apparatus has a foam impression block, and a carrier having a heel. The block has a toe thickness, a length and a heel thickness. The toe thickness is less than the heel thickness. The block is disposed upon the carrier such that the heel thickness and the heel are adjacent one another. 
     It is a further object of the present invention to provide an apparatus for measuring a plantar contour and an instep. The apparatus has a foam impression block and a carrier. The carrier has a heel and a plurality of straps. The block has a toe thickness, a length and a heel thickness wherein the toe thickness is less than the heel thickness. The block is disposed upon the carrier such that the heel thickness and the heel are adjacent one another. The plurality of straps are disposed upon the carrier and are adapted to wrap around the instep such that a plurality of sizing graduations disposed upon each of the straps are readable. 
     It is also an object of the present invention to provide a method for measuring the plantar contour of a foot. The method having the steps of: (1) placing the plantar contour over a foam impression block disposed upon a carrier having a heel wherein the block has a toe thickness, a length and a heel thickness, the toe thickness is less than the heel thickness, and the block is disposed upon the carrier such that the heel thickness and heel are adjacent one another; (2) aligning the toes with the toe thickness; and (3) urging the plantar contour into the block to deform the block. 
     It is a further object of the present invention to provide a method for measuring the plantar contour and instep of a foot. The method having the steps of: (1) placing the plantar contour over a foam impression block disposed upon a carrier having a heel and a plurality of straps, wherein the block has a toe thickness, a length and a heel thickness, the toe thickness is less than the heel thickness, the block is disposed upon the carrier such that the heel thickness and the heel are adjacent one another, and the plurality of straps are disposed upon the carrier are adapted to wrap around the foot; (2) aligning the toes of the foot with the toe thickness; (3) urging the plantar contour into the block to deform the block; (4) wrapping the straps around the instep such that a plurality of sizing graduations disposed upon each of the straps are readable; and (5) noting the sizing graduation indicated by each of the straps. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side perspective view of a first embodiment of the foam block of the present invention. 
     FIG. 2 is a rear perspective view of a second embodiment of the foam block of the present invention. 
     FIG. 3 is a front perspective view of a third embodiment of the foam block of the present invention. 
     FIG. 3 a  is a side view of a foot being placed on an embodiment of the foam block of FIG.  1 . 
     FIG. 3 b  is a side view of a foot being placed on an alternate embodiment of the container of FIG.  2 . 
     FIG. 3 c  is a rear view of a foot being placed on the container of FIG. 3 b.    
     FIG. 4 is a side perspective view of a foot being placed on the foam block of FIG.  1 . 
     FIG. 5 is a side perspective view of the foot fully deforming the foam block of FIG.  1 . 
     FIG. 6 is a side perspective view of the foot being removed from the deformed foam block of FIG.  1 . 
     FIG. 7 is a rear perspective view of the deformed foam block of FIG. 1 after the foot has been removed. 
     FIG. 8 is a front perspective view of the deformed foam block of FIG. 2 showing an instep measurement embodiment. 
     FIG. 9 is a rear perspective view of the foam block of FIG. 2 showing a wedge correction embodiment. 
     FIG. 10 a  is a side view of a first metatarsal support embodiment of the present invention. 
     FIG. 10 b  is a side view of a second metatarsal support embodiment of the present invention. 
     FIG. 11 a  is a rear view of a foot being placed into a dual density embodiment of the present invention. 
     FIG. 11 b  is a side view of the dual density embodiment of FIG. 11 a.    
     FIG. 12 is a perspective view of the heel guide embodiment of the present invention. 
     FIG. 13 is a perspective view of the clear embodiment of the container of the present invention. 
     FIG. 14 is a top view of a scanning mark embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the figures and more particularly to FIG. 1, a foam impression block is shown and is generally designated by the number  10 . Block  10  is made from pressure sensitive materials, which compress when a person&#39;s foot is pressed into the block. Preferably, block  10  comprises a foam casting material having low density, high flexural modulus and low shear strength. Accordingly, block  10  provides a material, which is easily deformed, with little or no memory, and retains the deformed shape indefinitely. Expanded phenolic materials such as those commonly used for insulation and ultra low density expanded polystyrene are suitable for block  10 . In the preferred embodiment, block  10  is expanded phenolic material. 
     Block  10  has a hardness or density from about 2 to about 25 pounds per square inch (hereinafter“psi”). Selection of the correct foam density depends on factors such as body weight, lifestyle or desired usage (e.g., sport, casual, or formal). For example, a density of about 2 psi is selected for casting a foot in block  10  while in the sitting position, a density of about 5 psi is selected for casting a foot in block  10  while in standing position, and a density of about 10 psi is selected for taking a dynamic casting of a foot in block  10  as described hereinbelow. 
     Shown in FIG. 1, block  10  has a toe thickness  14 , a heel  16 , a heel thickness  18 , and a length  19 . In one embodiment, toe thickness  14  and heel thickness are the same. In the preferred embodiment, toe thickness  14 , heel thickness  18  and length  19  provide the block with a wedge-like shape. In this embodiment, toe thickness  14  is less than heel thickness  18 , which minimizes any tendency for the toes of a person&#39;s foot to lift up while being pressed into block  10 . For instance in a first embodiment, heel thickness  18  is in a range from about 20 mm to about 35 mm and toe thickness  14  is in a range from about 10 mm to about 15 mm. In the preferred embodiment, heel thickness  18  is approximately 35 mm and toe thickness  14  is approximately 10 mm. 
     Block  10  is disposed upon the top of carrier  21 . Carrier  21  includes a heel  16  disposed on the bottom of the carrier. Heel  16  provides carrier  21  with a shape similar to a woman&#39;s shoe  5 . Block  10  is disposed upon carrier  21  such that heel thickness  18  and heel  16  are adjacent to one another. 
     Heel  16  improves the accuracy of the measurement of a person&#39;s foot using block  10 . Heel  16  and carrier  21  by more closely approximating the position and shape a foot assumes when wearing the desired shoe. An alternate embodiment of heel  16 , shown in FIG. 2, the slope of a man&#39;s shoe is approximated. In this embodiment, heel  16  and carrier  21  form an integral container  22 . In yet another embodiment of heel  16 , shown in FIG. 3, the slope of a sneaker or tennis shoe is approximated. In this embodiment, heel  16  and carrier  21  form integral container  22 . In yet another embodiment, block  10  is provided with heel  16  having an adjustable height. The height of heel  16  is adjustable from (1) a heel height less than the toe height, providing a negative slope to block  10 ; (2) a heel height equal to the toe height, providing no slope to block  10 ; (3) a heel height more than the toe height, providing a positive slope to block  10 . Preferably, container  22  is shaped so as to approximate the visual appearance of the exterior of a sole of a shoe. Moreover, the inside of container  22  is shaped having side-walls  22 - 1  at about a ninety degree angle with respect to its bottom surface  22 - 2  as shown in FIG. 11 a , or having side-walls  22 - 1  with a radius with respect to its bottom  22 - 2  as shown in FIG. 3 c.    
     In an alternate embodiment of FIGS. 3 b  and  3   c , container  22  includes a vertical guide portion  34 . Portion  34  extends upwardly from container  22  above the level of block  10 . Accordingly, portion  34  aids the user to align the foot with regards to block  10 . 
     In an alternative embodiment, carrier  21  and/or container  22  act to provide flexure to block  10 . In this embodiment shown in FIG. 3 a , carrier  21  includes a biasing section  23 . Biasing section  23  is positioned between heel  16  and toe portion  17 . Preferably, biasing section  23  is positioned between heel  16  and foot pivot point portion  13 . Biasing section  16  elastically flexes or biases under the weight of the user shown as position  23 - 1  and returns to its original position after use shown as position  23 - 2 . Accordingly, biasing section  23  further improves the accuracy and support of the measurement of a person&#39;s foot in a weighted position using block  10 . In another alternate embodiment, the amount of flexure in biasing section  23  is adjustable. The amount of flexure in biasing section  23  is adjustable either along the length of the foot, along the width of the foot, or along a combination of the length and width. 
     It should be recognized that combinations of heel  16 , carrier  21  and/or biasing section  23  which more closely approximates the position of the foot wearing the shoe is included within the scope of the present invention. 
     By way of example, the use of block  10  to measure a person&#39;s plantar contour is described below with reference to the embodiment of block  10  shown in FIG.  1 . The user positions one foot over block  10  with their toes toward toe thickness  14  and their heel towards heel thickness  18  and moves their foot towards block  10  in the direction shown by arrow A, shown in FIG.  4 . Next, the user applies weight to that foot in the direction shown by arrow A until block  10  is fully deformed, shown in FIG.  5 . The user&#39;s foot, with weight applied thereon, will conform to the shape the foot has when wearing a shoe having a heel height substantially equal to the height of heel  16 . Thus, block  10  will deform in the shape the user&#39;s foot will assume when wearing the shoe. Next, the user removes that foot from deformed block  10  in the direction shown by arrow B, shown in FIG. 6. A fully deformed block  10 , having the shape of the person&#39;s foot will conform to when wearing the shoe, is shown in FIG.  7 . 
     In an alternative embodiment of the present invention, block  10  has been modified to provide for measurement of the instep or top surface of the foot. This information is often also required to properly fit footwear. A person with a“high instep” would require a shoe that is deeper and may prevent the person from properly fitting into snugger fitting footwear. Further, by knowing the instep of a subject foot and knowing the internal geometry of a particular shoe, it is possible to determine if the shoe will fit properly. This information is vital when manufacturing custom plantar contours. For instance, if it is known via measurement using the present invention that there will be 2 mm of extra space in the shoe, it is possible to tailor the characteristics of the plantar contours to take up this extra space. 
     A plurality of straps  80  are used to characterize the instep, as shown in FIG.  8 . Each strap  80  has a plurality of graduations  81  on its top surface indicating instep range. Each strap  80  is disposed upon carrier  21  or container  22  and is run over the top of the foot, and the instep range is read off of graduations  81 . As an additional feature, straps  80  secure block  10  to the person&#39;s foot such that the person can walk with the block secured to their foot. Thus, straps  80  enable dynamic casting of the foot. The shifting in body weight and the changing of foot size, which occur as a result of walking, will therefore be captured by block  10 . Dynamic casting of the foot requires block  10  to have a density of at least  3  psi. 
     It is oftentimes desirable to make adjustments to the position of the foot. For instance, it is often desirable to manipulate the angle that the plantar contour of the foot has with respect to the floor to correct for excessive pronation, supination or the like. In this instance block  10 , as shown in FIG. 9, is further provided with a support  30 . Support  30  is insertable between block  10  and support  21  to correct for pronation or supination of the foot or for difference in the length of the leg. Alternately, support  30  is insertable into a slot  31  defined within container  22 . In another embodiment, support  30  is formed within carrier  21 /container  22 . Support  30  further improves the accuracy of the measurement of a person&#39;s foot by more closely approximating the position and shape their foot will assume when wearing the desired shoe having a desired level of pronation or supination correction. 
     In alternate embodiments, support  30  is a metatarsal support under block  10  shown in FIG. 10 a  or on block  10  as shown in FIG. 10 b . Support  30 , as a metatarsal support, further improves the accuracy of the measurement of a person&#39;s foot by more closely approximating the position and shape their foot will assume when wearing the desired shoe having a desired level of metatarsal support. 
     In yet another alternate embodiment shown in FIGS. 11 a  and  11   b  support  30  is provided by the selective use of various density foams within block  10 . In this instance, block  10  includes a region  10 - 1  having a first density and a region  10 - 2  having a second lower density. Region  10 - 1 , being of higher density, ensures that the heel of the user is properly centered within block  10 . Support  30  further improves the accuracy of the measurement of a person&#39;s foot by more closely approximating the position and shape their foot will assume when properly centered. For instance, in a preferred embodiment region  10 - 1  has a density of 5 psi and region  10 - 2  has density of 3 psi. In this embodiment, the higher density of region  10 - 1  ensures that the foot is properly centered within the lower density region  10 - 2 . 
     It should be recognized that support  30  which aids to adjust the foot within block  10  to more closely approximate the correct position of the foot wearing the shoe are included within the scope of the present invention. 
     It is desirable for container  22  to be used for more than one shoe size. In the embodiments where support  30  is secured within container  22 , the foot must be properly aligned over the support. Thus, a heel guide  44  shown in FIG. 12 is provided. Heel guide  44  enables container  22  to be used for more than one shoe size. Heel guide  44  is adapted to be removably coupled to container  22  in one or more positions such that the guide properly positions the foot of the user within the container. In a preferred embodiment, heel guide  22  includes studs  45  and container  22  includes recesses  46 . Studs  45  are adapted couple with recesses  46  to removably secure heel guide  44  to container  22 . Studs  45  are positioned on guide  22  and recesses  46  are positioned on container  22  so as to approximate the desired range of shoe sizes. 
     Shown in FIG. 3, a thin compliant medium  85 , such as, but not limited to, terry cloth, is placed on top surface block  10 . The foot is pressed into compliant medium  85 , which in turn compresses block  10 . Compliant medium  85  acts to prevent any of block  10  from adhering to the user&#39;s foot. 
     It is oftentimes desirable to mark specific points on the bottom of foot where problems, such as a metatarsal head, exists. In this instance, it is desirable for container  22  to be of optically clear material as shown in FIG.  13 . Optionally, only a portion of container  22  to be of optically clear material, such as bottom surface  22 - 2 . Preferably, clear container  22  includes a reference grid  60  disposed thereon. Optionally, reference grid  60  is a Harris mat, a pedo bar graph, a grid that relates to computer display software for corrections or the like. Clear container  22  therefor enables the user to remove block  10  from container  22 , to place their foot on reference grid  60  and precisely mark any existing problem spots. 
     As described above, the plantar contour measured by block  10  is often used in the manufacture of custom insoles. The process of converting the contour on block  10  into the custom insole often times requires using a scanner to digitize the contour directly from block  10 . In this instance, it is desirable for carrier  21  and/or container  22  to include one or more scanning reference marks  33  as seen in FIGS. 12 and 14. Mark  33  assists the optical scanner in the fast and accurate centering of the container and measured plantar contour. 
     Optionally, container  22  and/or carrier  21  includes mechanisms to secure block  10  therein. For example, in a first embodiment an adhesive is used to secure block  10  within container  22 . In alternate embodiments, indentations  70  (shown in FIG. 10 a ) or slots  71  (shown in FIG. 10 b ) are formed in container  22 . Indentations  70  and/or slots  71  allow removal of block  10  prior to deformation of the block. However, once deformed by the user, block  10  expands into indentations  70  and/or slots  71  to secure the block in container  22 . 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.