LAST, METHOD FOR MANUFACTURING THE LAST AND FOOTWEAR MADE FROM THE LAST

Abstract

Provided are a last for making an article of footwear, an article of footwear that is made from the last and a method for manufacturing the last. The last has dimensions defined by a last length, a joint girth, an instep girth and a heel breadth. In the last, a ratio of the last length to the joint girth is between 0.920 and 0.976, a ratio of the last length to the instep girth is between 0.945 and 1.006, and a ratio of the last length to the heel breadth is between 0.255 and 0.259. The last can provide a shape suitable for comfortably accommodating the elderly foot.

Description

TECHNICAL FIELD

The present application relates to a last for making an article of footwear, a method for manufacturing the last, and an article of footwear that is made from the last.

BACKGROUND

A last is a form or model in a rough shape of a human foot, which is used in footwear making to provide fit and style of an article of footwear. It is used by footwear makers in the manufacture or repair of the article of footwear.

The shape and internal space of an article of footwear are greatly determined by a last. Accordingly, the fit, function and comfort of the article of footwear depend on the last from which it is derived. There are many types of lasts which reflect the type of footwear and feet they are designed for. Different types of footwear require lasts with different characteristics. If the last better corresponds to human feet, there will be a better match between the foot and the footwear.

When a man is getting older, his feet will generally become broader and eventually cause further deformity such as hallus valgus, hammer toes, bunions and lesser digital deformity. The elderly with foot changes and deformities may find difficulties in choosing footwear since there is a lack of a last from which an article of footwear in conformity to the dimensions of the elderly foot can be derived. This results in a mismatch between the elderly foot and the footwear and affects the elderly in foot biomechanics and gait stability during walking. Furthermore, they easily get fall due to improper footwear wearing. Therefore, development of a last from which an article of footwear which fit with the elderly foot is derived is needed.

SUMMARY

According to an aspect of the present application, a last for making an article of footwear is provided, wherein the last may have dimensions defined by a last length, a joint girth, an instep girth and a heel breadth, and wherein a ratio of the last length to the joint girth may be between 0.920 and 0.976, a ratio of the last length to the instep girth may be between 0.945 and 1.006, and a ratio of the last length to the heel breadth may be between 0.255 and 0.259.

According to another aspect of the present application, an article of footwear having a shape complimentary to the last as mentioned above is provided.

According to yet another aspect of the present application, a method for manufacturing a last for making an article of footwear is provided, wherein the last may have dimensions defined by a last length, a joint girth, an instep girth and a heel breadth, and the method may comprise: setting the last length, the joint girth, the instep girth and the heel breadth of the last so that a ratio of the last length to the joint girth is between 0.920 and 0.976, a ratio of the last length to the instep girth is between 0.945 and 1.006 and a ratio of the last length to the heel breadth is between 0.255 and 0.259.

The present application overcomes the disadvantages of the prior art by providing a last based on foot data obtained through statistical researches on the elderly feet. An article of footwear made from the last is suitable for comfortably accommodating the elderly foot since the last contains the elderly foot dimensions and thus characters. Furthermore, the article of footwear made from the last can reduce the risks of fall among the elderly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a top view of a last according to an embodiment of the present application;

FIG. 2 illustrates a side view of the last according to the embodiment of the present application; and

FIG. 3 shows values for a last length, a joint girth, an instep girth and a heel breadth of the last according to the embodiment of the present application as graded for sizes 36 through 44.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, illustrative embodiments according to the present application will be described with reference to the accompanying drawings.

A last 10 in accordance with an embodiment of the present application is illustratively shown in FIGS. 1 and 2. As illustrated, shape of the last 10 may be defined by four dimensions, that is, a last length L, a joint girth JG, an instep girth IG and a heel breadth HB.

The last length L of the last represents an effective length of the last. The effective length is a horizontal distance from an effective end of the last to a heel tangent.

The effective end of the last indicates a position near a toe end beyond which the last is too narrow or too shallow to be regarded as a part of the space which needs to be provided in front of the toes of the foot to allow for movement. It is defined as the nearest position to the toe and where the last is 8 mm or more deep and 22 mm or more wide.

The heel tangent is a vertical transverse plane which touches the extreme back curve swell of the last at the heel and is perpendicular to an inside tangent when the last is standing normally and at its correct heel pitch. The inside tangent of the last indicates a vertical longitudinal plane which touches the last at an inside heel and inside joint swells when the last is standing normally and at its correct heel pitch. The inside heel is defined as the highest point of the inside curve swelling of the last at the heel area. The inside joint swell is defined as the highest point of the inside swelling in the first half of the last, which is actually referring to the position corresponding to the head of first metatarsophalangeal joint of a real foot. As known in the art, the heel pitch is a height of the extreme rear point of a bottom surface of the last above the horizontal when the last is placed on a level surface and held in the same attitude as if it was in the shoe. As the bottom surface of the last is not totally flat, the heel pitch is flexible and necessary to be obtained by measurement when no definite value is provided by the last manufacturer. It can be obtained, for example, by clamping the last, standing on a level surface, so that the height of the extreme toe end of the bottom surface above the horizontal is about 8 mm. Then, the required value of the correct heel pitch can be obtained by measuring the height of the extreme rear point of its bottom surface above the horizontal.

In the present application, a corrected effective length can be used as the last length L for characterizing the dimension of the last. The amount of the corrected effective length is the amount of the effective length plus a predetermined value. The predetermined value means the allowance giving for toe spacing within toebox, which can be 15 mm.

The joint girth JG represents a length of a continuous geodesic round the last which passes near an inside “joint” position. It can be understood that a last is different from a real foot, where there is no joint in a shoe last. The meaning of a joint in a last is actually referring to the position corresponding to the metatarsophalangeal joint of a foot (ball of the foot). It is shown in FIG. 1 as an oblique axis across the transverse vertical plane of the last. The joint girth of the last is defined as the circumference of this oblique cross section.

The instep girth IG is a length of a particular geodesic round the last which starts and ends at an instep point and perpendicular to the inside tangent. The instep point is a point on the last which corresponds in position to the instep point of the average foot which fits that size of shoe. The instep point of the foot is the highest point of the first metatarsal cuneiform joint.

The heel breadth HB is defined as a horizontal distance across the cross section of the heel swell, wherein the heel swell is defined as the highest point of the inside curve swelling of the last at the heel area.

In the last 10 according to the present embodiment, a ratio of the last length L to the joint girth JG may be set to be between 0.920 and 0.976, a ratio of the last length L to the instep girth IG may be set to be between 0.945 and 1.006, and a ratio of the last length L to the heel breadth HB may be set to be between 0.255 and 0.259.

A last with the above-mentioned ratios may define a space suitable for accommodating a human foot of which a ratio of a ball girth circumference to a foot length is 0.98, a ratio of an instep girth circumference to the foot length is 0.98, and a ratio of a heel breath to the foot length is 0.255.

For the human foot, a ball cross-section is a vertical cross section passing through MT (metatarsale tibiale: the most medially protruding point on the head of the first metatarsal bone) and MF (metatarsale fibulare: the most laterally protruding point on the head of the fifth metatarsal bone). The dimension “foot length” indicates a distance between pternion (the rearmost point of the heel) and a midpoint of the maximum breadth of the ball cross-section. The dimension “ball girth circumference” indicates a circumference of the ball cross-section. The dimension “instep girth circumference” indicates a circumference of a vertical cross-section of the foot perpendicular to the sagittal plane containing an axis of the foot axis at the 59% of the foot length. The dimension “heel breath” indicates a breadth of a heel measured perpendicular to the foot axis at the 16% of the foot length from pternion.

As will be discussed in below, a foot of an aged person is wider than a foot of a normal adult. Specifically, according to statistical researches on the elderly feet, for the aged person, the ratio of the ball girth circumference to the foot length is approximately 0.98, the ratio of the instep girth circumference to the foot length is approximately 0.98, and the ratio of the heel breath to the foot length is approximately 0.255. All of these three ratios are larger than those of the normal adult, respectively. Accordingly, the last may provide a space suitable for comfortably accommodating a foot of an aged person.

As mentioned above, the shape and internal space of an article of footwear are greatly determined by a last from which the article of footwear is derived. Accordingly, an article of footwear made from the above-mentioned last can also comfortably accommodating a foot of an aged person.

As a specific example, the last length, the joint girth, the instep girth and the heel breadth of the last with a size from 36 to 44 are determined in accordance with respective values as represented in FIG. 3. As shown in FIG. 3, the ratio of the last length to the joint girth, the ratio of the last length to the instep girth, and the ratio of the last length to the heel breadth of the last are reduced, respectively, as the size of the last increases from size 36 to 44.

Hereinafter, a process for design the last which can define a space for comfortably accommodating a foot of an aged person will be discussed in detailed.

It can be understood that knowledge of foot shape is important to develop the last. However, studies of foot shape about the elderly are rare. There is a need to have a better understanding on the foot shape of the elderly for last design. To that end, 499 elderly anthropometry foot data are collected.

A sample of 499 elderly, each of which has an age of 60 or above and is able to achieve equal weight bearing on bare feet, is recruited to collect their foot data. 11 surface landmarks of each foot of the 499 elderly are identified and then allocated with stickers (4 mm in diameter) by an experienced physiotherapist, wherein the sticker is a reflective marker which is stuck on foot skin for defining a bony landmark of the foot during scanning. Then each person is asked to stand bare feet with equal weight on a 3-D foot laser scanner (for example, INFOOT made in Japan). Both feet are then scanned one by one. The scanning takes about 10 seconds. 18 parameters containing elderly foot data are collected and calculated automatically by, for example, the INFOOT software. The particular steps for collecting and calculating the elderly foot data will not be discussed in detailed since they are well known in the art.

Based on the computerized and analyzed foot data, it can be seen that there are no significant paired differences between a left foot and a right foot in all foot parameters. In addition, there is an increase in all foot parameters when the foot length increases. This indicates that there is an increase in other foot dimensions when the size of the foot becomes larger. Especially, the ball girth circumference and instep girth circumference increase in a larger extend when the foot length increases. This indicates that an enough space should be provided in these regions when designing the last. Moreover, the heel breadth is also increased when the foot length becomes larger. All these variations of elderly feet provide a useful guideline to design the last for the elderly. Table 1 shows a result of comparison between the elderly foot and the standard adult foot.

TABLE 1
Result of 499 elderly foot data
	Elderly foot	Standard Adult	Comparison
Ratio	(N = 499)	foot	(100%)
ball girth	0.98	0.94	+4.26%
circumference:foot
length
instep girth	0.98	0.97	+1.03%
circumference:foot
length
heel breath:foot	0.265	0.255	+3.92%
length

From Table 1, it can be seen that, for the elderly foot, the ratio of the ball girth circumference to the foot length, the ratio of the instep girth circumference to the foot length, and the ratio of the heel breath to the foot length are larger than those of the normal adult, respectively.

The foot dimension parameters are divided and classified into different groups according to the foot length. This would facilitate matching between the foot and a last contour when designing a series of lasts for the elderly. Furthermore, averaged values for the parameters are generated in each group. The finalized anthropometry foot data are selected and used to determine the dimensions of the last.

As mentioned above, the elderly foot usually gets deformity and swelling, thus adequate forefoot fit and a midfoot fit are necessary. In addition, not enough heel gripping would also cause slipping. So, rearfoot fitting is also important on the last design for the elderly. However, a direct transfer of foot measurements into last design could not guarantee proper footwear fit since the last contour is not exactly the same as the foot shape. Therefore, only some variables are selected to match between foot and last contour, and to make sure forefoot, midfoot and rearfoot fit.

According to an embodiment of the present application, four foot parameters are selected to design the last, as shown in Table 2. Specifically, the last length, the joint girth, the instep girth and the heel breadth of the last are corresponding to and derived from the foot length, the ball girth circumference, the instep girth circumference and the heel breath, respectively.

TABLE 2
Foot parameters corresponding to the last dimensions
	Regions	Selected foot parameters	Last dimensions
	Length	Foot length	Last length
	Forefoot	Ball girth circumference	Joint girth
	Midfoot	Instep girth circumference	Instep girth
	Rearfoot	heel breath	Heel breadth

It should be noted that, the foot length is not exactly matched with the last length since some space should be allowed in a toe region of the last. As an example, an allowance of 15-21 mm may be given to fit between the foot and the last. For example, if the elderly with a foot length were 217 mm, a foot with a foot length of 217 mm would match with a last with a last length 234.68 mm.

According to the trend of the foot data result, matching and some modification, the dimension of last was generated from size to size. FIG. 3 shows that the last dimension changed in a systemic manner.

Hereinabove, illustrative embodiments according to the present application are described with reference to the accompany drawings. However, as obvious for those skilled in the art, it is not necessary to contain all elements mentioned above in one solution. Any suitable combination of the described elements may be combined to implement the present application.

Claims

1. A last for making an article of footwear, wherein the last has dimensions defined by a last length, a joint girth, an instep girth and a heel breadth, wherein a ratio of the last length to the joint girth is between 0.920 and 0.976, a ratio of the last length to the instep girth is between 0.945 and 1.006, and a ratio of the last length to the heel breadth is between 0.255 and 0.259.

2. The last of claim 1, wherein the last defines a space suitable for accommodating a human foot of which a ratio of a ball girth circumference to a foot length is 0.98, a ratio of an instep girth circumference to the foot length is 0.98, and a ratio of a heel breath to the foot length is 0.255.

3. The last of claim 1, wherein the last defines a space suitable for comfortably accommodating a foot of an aged person.

4. The last of claim 1, wherein the ratio of the last length to the joint girth, the ratio of the last length to the instep girth, and the ratio of the last length to the heel breadth of the last are reduced, respectively, as a size of the last increases from size 36 to 44.

5. The last of claim 1, wherein the last length, the joint girth, the instep girth and the heel breadth of the last with a size from 36 to 44 are determined in accordance with respective values represented in FIG. 3.

6. An article of footwear having a shape complimentary to the last of claim 1.

7. The article of footwear of claim 6, wherein the last length, the joint girth, the instep girth and the heel breadth of the last with a size from 36 to 44 are determined in accordance with respective values represented in FIG. 3.

8. A method for manufacturing a last for making an article of footwear, wherein the last has dimensions defined by a last length, a joint girth, an instep girth and a heel breadth, the method comprising:

setting the last length, the joint girth, the instep girth and the heel breadth of the last so that a ratio of the last length to the joint girth is between 0.920 and 0.976, a ratio of the last length to the instep girth is between 0.945 and 1.006 and a ratio of the last length to the heel breadth is between 0.255 and 0.259.

9. The method of claim 8, further comprising:

setting the last length, the joint girth, the instep girth and the heel breadth of the last so that the ratio of the last length to the joint girth, the ratio of the last length to the instep girth, and the ratio of the last length to the heel breadth of the last are reduced respectively as a size of the last increases from size 36 to 44.

10. The method of claim 8, further comprising:

setting the last length, the joint girth, the instep girth and the heel breadth of the last with a size from 36 to 44 in accordance with respective values represented in FIG. 3.