An insole is generally defined in the trade to be a material to which an upper and an outsole are secured. In a typical lasted shoe construction, an insole is temporarily secured to an underside of a last and the upper may be pulled down and around the underside of the insole. The upper may then be wiped, or shaped, about the last prior to attachment to the insole. Once the upper is secured, either by cement or stitch, to the underside of the insole, and after the insole is secured to an outsole either by fasteners or cement, the last is usually removed. The typical resulting structure is the upper being indirectly secured to the outsole where the insole is connecting both the upper and outsole together.
Because the insole normally provides a base to which the upper is attached, and because the insole often links and secures the upper to the outsole, the insole is generally made of a material having sufficient structural integrity. A soft material may easily flex or buckle when the shoe is subjected to stress, possibly resulting in the insole separating from the cement or fasteners and, therefore, causing the insole to separate from the outsole and/or upper. Hence, the insole is often a rigid material so as to minimize the disadvantages described above and inhibit parts of the shoe from falling apart. As one may imagine, utilizing a rigid, strong material having sufficient structural integrity may often result in an insole that has reduced flexibility.
In some cases, an inflexible insole causes the shoe to be uncomfortable, particularly if a wearer's foot directly contacts the insole. As shoe construction evolved, comfort was improved by placing a cushion on top of the insole for directly receiving the wearer's foot. Instead of, or in addition to, the cushion, a footbed or socklining may be used. Further, using a cushion, footbed, or socklining of soft or resilient material may also permit these items to be easily flexed. However, despite the addition of a cushion, footbed, or socklining, the flexibility or comfort of the insole may be unaffected.
U.S. Pat. No. 4,115,934 to Hall, U.S. Pat. No. 6,178,663 to Schoesler, U.S. Pat. No. 5,438,768 to Bauerfeind, and U.S. Pat. No. 6,598,319 to Hardt appear to disclose an inner sole or insole having a flexible or cushioned insert to improve flexibility and/or cushioning. The inner sole or insole may directly receive the wearer's foot and does not tend to show the inner sole or insole as a structure for indirectly securing the upper to the outsole where the insole is connecting both the upper and outsole together. In some cases, the inner sole or insole may be inserted into the shoe. Hence, these references that refer to an inner sole or insole do not employ the use of an insole as defined by this specification.
What is desired, therefore, is a shoe having an insole with improved flexibility without sacrificing structural integrity. Another desire is a shoe having an insole with improved comfort.