WO1999048397A1

WO1999048397A1 - Lasted footwear

Info

Publication number: WO1999048397A1
Application number: PCT/US1999/006338
Authority: WO
Inventors: Jeffrey S. Brooks
Original assignee: Jeffrey S. Brooks, Inc.
Priority date: 1998-03-25
Filing date: 1999-03-23
Publication date: 1999-09-30
Also published as: AU3200099A

Abstract

Lasted footwear including a last board (12), an outsole attached to the last board (12) and extending downwardly therefrom, and an upper attached to the last board (12) and zone of weakness (42) extending generally transversely with respect to the last board (12) along a curve extending through phalangeal joints of a foot of a person wearing the footwear. The zone of weakness (42) provides greater flexibility for easier articulation of the metatarsals (M1-M5) relative to the phalanges (P1-P5) of the foot.

Description

LASTED FOOTWEAR

Background of the Invention

This invention relates generally to footwear and, more particularly, to footwear manufactured using a lasting process .

Many types of shoes, boots and other footwear are fabricated using a lasting process. In this process, a last board of relatively stiff material (e.g., cellulose) is temporarily affixed, as by staples, to a metal or plastic form called a "last". An upper is applied over the last and secured at its edges to the last board using adhesive or stitching. An outsole is then attached to the last board and to portions of the upper, typically by gluing, after which the footwear is removed from the last and finished.

The stiffness of the last board and outsole tends to inhibit flexure of the foot in the area of the metatarsal phalangeal joints. These joints are located between the proximal phalanges (i.e., the rear toe bones) and the metatarsals (i.e., the bones overlying the forward portion of the arch) . The stiffness of the last board and outsole inhibit dorsiflexion during which the phalanges flex upward relative to the metatarsals.

Because the aforementioned stiffness inhibits flexure, the footwear may be uncomfortable, especially during break-in. There is a need, therefore, for lasted footwear (i.e., footwear manufactured using a lasting process) which is more flexible, particularly in an area generally corresponding to the metatarsal phalangeal joints of the foot. Summary of the Invention

Among the several objects of this invention may be noted the provision of lasted footwear which is constructed to have greater flexibility in the aforesaid metatarsal phalangeal joint area; the provision of such footwear which is more comfortable and which reduces the risk of over stress and injury to the foot; the provision of such footwear which readily accommodates the natural flexure of the foot for ease of movement; the provision of such footwear which can be manufactured using conventional lasting techniques; and the provision of such footwear which does not cost significantly more to produce than conventional lasted footwear.

In general, lasted footwear of the present invention comprises a last board, an outsole attached to the last board and extending downwardly therefrom, and an upper attached to the last board and extending upwardly therefrom. The improvement comprises a zone of weakness extending generally transversely with respect to the last board along a curve extending through locations generally corresponding to the five metatarsal phalangeal joints of a foot of a person wearing the footwear. This zone of weakness provides greater flexibility for easier articulation of the metatarsals relative to the phalanges of the foot.

In another aspect of the invention, the last board comprises a first area for underlying a heel and a midfoot of a wearer. The first area has a first flexure stiffness. The last board also comprises a second area positioned in front of the first area for underlying five metatarsal phalangeal joints of the wearer. The second area has a second flexure stiffness less than the first- flexure stiffness for providing the footwear with greater flexibility in a region corresponding to the metatarsal phalangeal joints. In addition, the last board comprises a third area positioned in front of the second area for underlying a forefoot of the wearer. The third area has a third flexure stiffness greater than the second flexure stiffness .

Other objects and features will become in part apparent and in part pointed out hereinafter.

Brief Description of the Drawings Fig. 1 is medial side elevation of a foot showing the first metatarsal phalangeal joint, the foot being shown in a rest or mid-stance position;

Fig. 2 is a top view of the foot of Fig. 1 showing all five metatarsal phalangeal joints; Fig. 3 is a vertical section of a lasted shoe as viewed from the medial side of the foot, portions of the foot being shown in phantom in a rest or mid-stance position;

Fig. 4 is a view similar to Fig. 3 but showing the foot and the shoe in a toe-off position;

Fig. 5 is a top view of a last board made to have a zone of weakness formed by a slot in accordance with this invention, portions of the phalangeal joints being shown in phantom to define the location of the zone of weakness; Fig. 6 is a view similar to Fig. 5 showing a zone of weakness formed by a series of perforations in the last board;

Fig. 7 is a view similar to Figs. 5 and 6 showing a zone of weakness formed by using a more flexible material; and Fig. 8 is a view similar to Figs. 5-7 showing a zone of weakness formed by a series of narrow slots in the last board.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings .

Detailed Description of the Preferred Embodiment

Referring now to the drawings, and first more particularly to Figs. 1 and 2, a foot is generally designated by the reference character F. Toward the front end of the foot F (to the left as shown) is a first metatarsal phalangeal joint, generally designated Jl , which is formed at the junction of a first metatarsal Ml and a first proximal phalange PI extending along the medial side of the foot. When the foot F is at rest on the ground as shown in Fig. 1, the angle A between the first metatarsal Ml and the first proximal phalange PI is generally in the range of from about fifteen degrees to about twenty degrees. However, during dorsiflexion, such as during the toe-off portion of a gate as shown in Fig. 4, this angle A increases to between about 65 degrees and about 75 degrees. As angle A increases, the first metatarsal Ml rotates upward generally about a lateral (i.e., transverse) axis LI through the first metatarsal head HI at the forward end of the first metatarsal, while the first proximal phalange PI remains generally parallel with the ground. Thus, during toe-off the forefoot FF (generally corresponding to the toes) remains flat against the ground while the midfoot MF and the heel HE of the foot raise off the ground. The second through fifth metatarsal phalangeal joints J2-J5 shown in Fig. 2, located between the second through fifth metatarsals M2-M5 and second through fifth phalanges P2-P5, respectively, behave in much the same way as does the first joint Jl . That is, during dorsiflexion the respective angles (not shown in Fig. 2) between each of the metatarsals M2-M5 and the phalanges P2-P5 increase as the metatarsals rotate upward onto their respective heads H2-H5 about their respective lateral axes L2-L5. Footwear made using a lasting process is generally designated by the reference numeral 10 in Fig. 3. During the lasting process, a last board (generally designated 12) of relatively stiff material (e.g., cellulose) is temporarily fastened, such as by stapling, to a metal or plastic last (not shown) . The last board 12 is fastened to the last so that its upper face 14 contacts the last. An upper 16 is fitted over the last and the last board 12 so that a lower edge margin 18 of the upper overlaps a peripheral edge margin 20 of the last board. Once in place, the margins 20, 18 of the last board 12 and upper 16 are permanently fastened to each other such as by gluing or stitching. An outsole 22 comprising one or more layers of shoe material, such as rubber or leather, is applied to a lower face 24 of the last board 12 opposite the last and fastened in place by conventional means such as by adhesive bonding. After applying the outsole 22, the footwear 10 is removed from the last and an insole 26, which may or may not include a sockliner, is applied to the upper face 14 of the last board 12. The insole 26 may be removeable or permanently attached to the last board 12 by conventional means such as adhesive bonding. The foregoing description of lasted footwear 10 and the process for 6 making such footwear is conventional and, therefore, will not be described in further detail.

As may be seen by a comparison of Figs. 3 and 4, regions of the outsole 22, last board 12 and insole 26 corresponding to and underlying each of the five metatarsal phalangeal joints J1-J5 of the wearer bend when the wearer dorsiflexes his or her foot F. Further, as will be understood by those skilled in the art, the stiffnesses of the last board 12 and outsole 22 tend to inhibit flexure (particularly dorsiflexion) of the foot F in the area of the metatarsal phalangeal joints J1-J5. To accommodate these flexures, the last board 12 of the preferred embodiment, illustrated in Fig. 5, includes a zone of weakness, generally designated 30, which allows the last board to bend more readily under the metatarsal heads H1-H5 (Fig. 2) as the foot F (Fig. 2) dorsiflexes.

As further illustrated in Fig. 5, the zone of weakness 30 extends across the last board 12 from a location corresponding the medial side of the foot adjacent the first metatarsal phalangeal joint Jl to a location corresponding to the lateral side of the foot adjacent the fifth metatarsal phalangeal joint J5. Moreover, the zone 30 extends generally transversely with respect to the last board 12 along a curve C extending through locations generally corresponding to the five metatarsal phalangeal joints J1-J5 (Fig. 2) of a foot F of a person wearing the footwear 10 (Fig. 3) . These locations also closely correspond to the proximal ends of the proximal phalanges P1-P5 of the first through fifth toes of the foot. As will be apparent to those skilled in the art, the zone of weakness 30 provides greater flexibility for easier articulation of the metatarsals M1-M5 relative to the phalanges P1-P5 of the foot F. The zone of weakness 30 may be formed in any of several ways. By way of example, the zone 30 may be manufactured as a slot 32 formed in the last board 12, as shown in Fig. 5. Most preferably, when the zone 30 is manufactured as a slot 32, its width W is chosen such that a front distal edge 34 of the slot is spaced sufficiently from a rear proximal edge 36 of the slot to avoid interference between the edges when the portion of the last board 12 rearward of the slot is flexed upwardly relative to a front portion of the last board forward of the slot through an angle of up to about 65 degrees. For example, for a last board 12 having a thickness T (Fig. 3) in the range of between about one and about 2.5 millimeters, the width W of the slot 32 in a direction extending in front- to-back direction relative to the foot is within the range of about one to about five millimeters or more.

As further illustrated in Fig. 5, the construction described above forms a last board 12 having three distinct regions or areas indicated at 40, 42 and 44. The first area 40 underlies the heel HE (Fig. 1) and the midfoot MF (Fig. 1) of a wearer. This area 40 has a stiffness approximately equal to the flexure stiffness of conventional last boards. Flexure stiffness refers to the stiffness of the board when subjected to bending. The second area 42, positioned in front of the first area 40, underlies the five metatarsal phalangeal joints J1-J5 (Fig. 2) of the wearer. This area 42 has a flexure stiffness which is less than that of the first area 40. The third area 44 is positioned in front of the second area 42 and underlies the forefoot FF of the wearer. This area 44 has a flexure stiffness which is greater than that of the second area 42 and preferably (but not necessarily)- approximately equal to the flexure stiffness of conventional last boards. As will be apparent to those skilled in the art, this construction provides the footwear 10 with greater flexibility in a region corresponding to the metatarsal phalangeal joints J1-J5. The first and third areas 40, 44, respectively, are joined by a medial connecting strip 50 extending from a forward medial corner of the first area to a rearward medial corner of the third area and by a lateral connecting strip 52 extending from a forward lateral corner of the first area to a rearward lateral corner of the third area. Thus, the connecting strips 50, 52 and the first and third areas 40, 44, respectively, have a unitary construction and may be formed from a single piece of sheet material. Further, the connecting strips 50, 52 and the first and third areas 40, 42, respectively, have a substantially uniform thickness T. It will be understood, however, that the connecting strips 50, 52 and the first and third areas 40, 44, may be fabricated from separate pieces of material without departing from the scope of the present invention. Moreover, the components may be made of the same material or of different materials, and the thickness of the last board 12 may vary throughout the various components.

In another embodiment, the zone of weakness 30 may be manufactured by forming a series of perforations 60 in the last board 12 as shown in Fig. 6. As will be appreciated by those skilled in the art, when the zone 30 is formed as a series of perforations 60, the first and third areas, 40, 44, respectively, are joined by a plurality of connecting strips 62 extending from the first area to the third area, including the medial and lateral connecting strips, 50, 52, respectively. In yet another embodiment shown in Fig. 7, the zone of weakness 30 may be manufactured by fabricating the last board 12 of two flexible materials, a first flexible material outside the zone of weakness and a second less flexible material in the zone of weakness. In an alternate embodiment (not shown) , the second material may extend entirely across the last board 12 so that the medial and lateral connecting strips 50, 52 are eliminated. Moreover, as illustrated in Figs. 3 and 4, the outsole 24 may be formed to have a zone of weakness 70 generally corresponding in location to the zone of weakness 30 in the last board 12 to provide even greater flexibility to the footwear 10.

Fig. 8 illustrates still another embodiment in which the zone of weakness 30 is formed by a series of narrow slots 80 in the last board 12. Those skilled in the art will appreciate that the zone of weakness may be formed in other ways without departing from the scope of the present invention. Although other materials may be used to make the last board 12 without departing from the scope of the present invention, the last boards of the preferred embodiments are made of Exl, AIRFLOW 2000 or TEXON^® last board material. Each of these materials is available from Hao Shih Duo International Co., Ltd. of Yuan-Lin, Chung-Hwa Hsien, Taiwan ROC. Texon^® is a federally registered trademark owned by DVSG Holding GmbH of Frankfurt Germany. Because footwear 10 constructed as described above has greater flexibility in the area of the wearer's metatarsal phalangeal joint J1-J5, the footwear is more comfortable and reduces the risk of over stress and injury to the foot F. In addition, this footwear 10 readily accommodates the natural flexure of the foot F for ease of 10 movement. As will be understood by those skilled in the art, because last boards 12 of the present invention are unitary, footwear 10 can be manufactured with these last boards using conventional lasting techniques. Further, because the footwear 10 may be made with minimal additional operations, it does not cost appreciably more to produce than conventional lasted footwear.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense .

Claims

11ClaimsWHAT IS CLAIMED IS

1. Lasted footwear comprising a last board, an outsole attached to the last board and extending downwardly therefrom, and an upper attached to the last board and extending upwardly therefrom, wherein the improvement comprises a zone of weakness extending generally transversely with respect to the last board along a curve extending through locations generally corresponding to the proximal ends of the proximal phalanges of the first through fifth toes of a foot of a person wearing the footwear, said zone of weakness providing greater flexibility for easier articulation of the metatarsals relative to the phalanges of the foot .

2. Lasted footwear as set forth in claim 1 wherein said zone of weakness comprises a slot in said last board.

3. Lasted footwear as set forth in claim 2 wherein said slot has a front distal edge, a rear proximal edge, and a width between the edges sufficient to avoid interference between the edges when a back portion of the last board rearward of the slot is flexed upwardly relative to a front portion of the last board forward of the slot through an angle of up to about 65 degrees.

4. Lasted footwear as set forth in claim 1 wherein said zone of weakness comprises a series of perforations in said last board. 12

5. Lasted footwear as set forth in claim 1 wherein said last board is fabricated of a first flexible material outside said zone of weakness, and a second less flexible material in said zone of weakness.

6. A last board for use in footwear comprising said last board, an outsole attached to said last board and extending downward therefrom, and an upper attached to said last board and extending upward therefrom, said last board comprising: a first area for underlying a heel and a midfoot of a wearer, said first area having a first flexure stiffness; a second area positioned in front of said first area for underlying five metatarsal phalangeal joints of the wearer, said second area having a second flexure stiffness less than said first flexure stiffness for providing the footwear with greater flexibility in a region corresponding to said metatarsal phalangeal joints, said second area having a width less than about five millimeters; and a third area positioned in front of said second area for underlying a forefoot of the wearer, said third area having a third flexure stiffness greater than said second flexure stiffness and a rear boundary generally extending along a line underlying the proximal ends of the five proximal phalanges of the wearer.

7. A last board as set forth in claim 6 wherein said first and third areas are joined by at least one strip extending from said first area to said third area. 13

8. A last board as set forth in claim 10 wherein said strip and said first and third areas have a unitary construction and are formed from a single piece of sheet material .

9. A last board as set forth in claim 8 wherein said at least one strip comprises a medial strip extending from a forward medial corner of said first area to a rearward medial corner of said third area and a lateral strip extending from a forward lateral corner of said first area to a rearward lateral corner of said third area.

10. Lasted footwear comprising a last board, an outsole attached to the last board and extending downwardly therefrom, and an upper attached to the last board and extending upwardly therefrom, wherein the improvement comprises a zone of weakness extending generally transversely with respect to the last board along a curve extending through locations generally corresponding to the five metatarsal phalangeal joints of a foot of a person wearing the footwear, said zone of weakness having a width in a direction extending in a front-to-back direction relative to the foot in the range of about one to five millimeters for providing greater flexibility for easier articulation of the metatarsals relative to the phalanges of the foot .