The present invention provides a foot measuring system that includes a support surface on which a foot is placed, a plurality of movable measurement structures each having a first end and a second end, an inflatable diaphragm for contacting the first end of each the structure and forcing a movement of each structure from an initial position toward a measurement position, and a measurement device for measuring the measurement position relative to the initial position of each the structure, after the movement of each the structure, to determine a shape of the foot.
In a preferred embodiment, the structures are elongated gauge pins oriented in a direction perpendicular to a plane of the support surface. The support surface includes a plurality of holes through which the second end of each of the structures can be advanced toward the foot in response to the upward pressure exerted by the inflated diaphragm.
In another preferred embodiment of the present invention, the gauge pins are measured by an array of electrostatic sensors that can sense the relative positions of an embedded metalized area on each gauge pin. These electrostatic sensors are mounted as a group on a circuit board with each sensor located at each gauge pin. This circuit board is moved in a direction corresponding to the lengthwise direction of the gauge pins. When the electrostatic sensor encounters the metalized area on a gauge pin, the relative position of each pin is determined. The relative position, or measurement position is determined by the distance traveled by the circuit board along each gauge pin until the sensor at each gauge pin detects the metalized area. This distance will vary at each gauge pin, resulting in an array of values representing the shape of the foot.
The diaphragm is preferably connected to a bottom surface of the measurement system to form an airtight cavity between portions of the diaphragm and the bottom surface. An air controller is connected to the cavity to controllably introduce air into the cavity to force the gauge pins upward toward the foot.
The system also includes a processor for controlling the air controller, the circuit board and sensors, and for at least retrieving measurement information. The processor may also be utilized to build a digital representation of the shape of the foot based on the measurement information. In one embodiment, the processor determines the initial position of each the structure prior to inflating the diaphragm, inflates the cavity, compares the initial position of each the structure with the measurement position of the each the structure after the diaphragm is inflated and each the structure stops moving do to restrictions caused by the inflated diaphragm and by the foot.
Embodiments of certain aspects of the measurement system, such as embodiments of the circuit board and gauge pins, are described in U.S. Pat. No. 5,640,779 to Rolloff et al., and U.S. Pat. No. 5,941,835 to Sundman, both of which are incorporated in their entirety by reference herein. Other embodiments of the circuit board and gauge pins are described in U.S. Pat. No. 6,864,687 to Walker et al., which is incorporated in its entirety by reference herein.
The system also preferably includes a protective diaphragm located at or near the surface that prevents contamination of the system through the top of the system when the foot is placed on the surface, yet does not restrict the movement of the plurality of structures beyond the surface. In a preferred embodiment, the contour sampling device of the present invention has incorporated therein a diaphragm disposed about the top of the unit between the gauge pins and the subject foot. The protective diaphragm is preferably made from a stretchable and flexible material. This diaphragm may be mounted to a liquid shedding frame.
In order to reduce the likelihood that any restriction on the gauge pin exists as a result of the protective diaphragm, the protective diaphragm's frame can be mounted above the top surface of the unit. This mounting distance is a significant fraction of the dynamic range of the gauge pins. In a preferred embodiment this distance is in the range between about 3-30 mm.
A toe plate may also be included, which is a device that is slid under the forefoot, typically forward of the ball of the foot to prevent the toes from being pushed up by the gauge pins. While a device such as a toe plate that selectively restricts the upward motion of the gauge pins can be diagnostically useful, its placement requires some care and may therefore be undesirable in a measurement device for the retail market.
In an alternate embodiment, the need for a toe plate has been eliminated by placing the toes purposely off the end of the array of gauge pins. Pin locations are further tailored to prevent unnecessary upwards motion of the toe end of the foot. To assist the user in positioning the foot, a ridge of material in a shape designed to be similar to the shape of the transverse sulcus of the foot is provided. When the foot is placed against the top of the scanner, the toes are positioned forward of this ridge with the ball of the foot behind it. All areas behind the ridge will be periodically sampled by the gauge pins.
The present invention also provides a method for measuring the contours of a foot. The method includes placing the foot against the support surface of the foot measuring system, and inflating the diaphragm to force the plurality of movable measurement structures, such as the gauge pins, through the surface a toward the foot to move each structure due to contact between the first end of each structure and the diaphragm. Each structure is limited in its movement toward the foot by contact between the second end of the structure and the foot. The method further includes detecting a change in position of each structure relative to an initial position of each structure before the diaphragm was inflated, and measuring a shape of the foot based upon the change in position of each structure.
As discussed above, the measurement structures are preferably elongated gauge pins used in conjunction with a circuit board having a plurality of sensors, each of which corresponds to a single gauge pin and senses a selected area of each gauge pin to determine a position of each gauge pin. In another embodiment, the method includes determining the initial position of each structure prior to inflating the diaphragm, followed by comparing the initial position of each structure with a position of each structure after the diaphragm is inflated and each structure stops moving do to restrictions caused by the inflated diaphragm and by the foot.
The method described above may be performed a single time to measure the shape of the foot, or may be performed multiple times on the foot. A single measurement would be useful to save time in taking a measurement of the shape of the foot. Multiple measurements can also be performed in relatively quick succession to ensure that the measurement is accurate, and/or to determine whether the foot moved during measurement.
Click to expand...