Geometrical instruments – Distance measuring – Opposed contacts
Reexamination Certificate
1999-02-03
2001-03-27
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Distance measuring
Opposed contacts
C033S203000, C033S555100
Reexamination Certificate
active
06205672
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to measuring devices, particularly to devices that measure the diameter of circular objects, particularly those devices that measure the diameter of wheels, tires and similar vehicle support devices. More particularly, this invention relates to apparatus for the digital measurement and calibration of items. Most particularly, this invention relates to the digital measurement of diameter, circumference and the acquiring and storage of ancillary measurements.
2. State of the Art
Tire diameter is an important variable for determining the speed of an automobile. Each time a tire completes one full rotation, the vehicle it is mounted on will have gone forward (or backward) one circumference of the tire. Therefore, knowing the number of times per unit time (second or minute) the tire rotates will be directly proportional to the speed of the vehicle. But if the diameter of the tire is not correct, the speed of the vehicle will register incorrectly as well; the apparent speed will decrease as the actual size of the tire increases. The effect is especially important in automobile racing. There the exact speed is essential, moreover, the faster speed makes a small error in readout read more in absolute terms.
Conventional tire calipers measure the diameter of the tire while the vehicle is at rest. The caliper is placed over the tire and the diameter is read off a measuring device on the caliper. The optical reading of the diameter can lead to incorrect determinations of the diameter. Moreover, the markings on the caliper are difficult to read.
It would be of great benefit to have a caliper that was more easily readable and more accurately readable than the current calipers.
SUMMARY OF THE INVENTION
This invention provides an apparatus and method for measuring tires accurately and quickly using a tire caliper that outputs data in digital form. A measuring instrument determines the diameter of automotive tires, preferably automotive race tires, and displays the circumference or the diameter at the users option. The tool of this invention has a digital display including a relatively elongate caliper body formed with a measuring part adapted to make measuring engagement with the tire to be measured. A member freely slidable in a longitudinal direction of the caliper body and formed with a measuring part disposed opposite to the measuring part of the caliper. In one preferred embodiment, the measuring instrument is marked with a transparent linear scale fixedly disposed on the caliper body with its axis extending in the longitudinal direction of the caliper body and a transparent index scale is mounted on the slider with its calibrated face disposed opposite to the calibrated face of the linear scale in a slightly spaced apart relationship. In this embodiment, a measuring circuit including a digital display element is mounted in the slider and is electronically connected to a light emitting element and a light receiving element mounted in the slider. The light emitting element and the light receiving element are disposed opposite to each other with the linear scale and the index scale interposed therein between. The measuring circuit converts the measured tire diameter into the tire circumference measurement, which is digitally displayed on the LCD. In one particularly preferred embodiment, the circuitry allows the measurements of the front, right rear, left front and left rear tires to be recorded for a later reading of those measurements.
One aspect of this invention is a tire caliper comprising:
an elongate bar;
a first tire sensing rod affixed in perpendicular orientation proximate a first end of the elongate bar;
a slidable housing mounted on the rod and positionable from the location of the first bar to proximate the second end of the elongate bar;
a second tire sensing rod in perpendicular orientation with the elongate bar, and coplanar with and disposed on the same side of the elongate bar as the first tire sensing rod, the second rod affixed to the slidable housing;
a sensor within the slidable housing for providing indicia of the location of the second tire sensing rod on the elongate bar;
a processing means electrically connected to the sensor to sense the position of the sensor; and
a digital means to display the position of the sensor electrically connected to the processing means.
A second aspect of this invention is a method for measuring a tire comprising:
placing a tire caliper having a digital read out so that one rod of the caliper touches the tire;
placing the second rod at the maximum distance from the first rod while still remaining in contact with the tire; and
reading the numerical display from the digital readout
A third aspect of this invention is a tire caliper comprising:
an elongate bar;
a first tire sensing rod affixed in perpendicular orientation proximate a first end of the elongate bar;
a slidable housing mounted on the elongate bar and positionable from the location of the first bar to proximate the second end of the elongate bar, the first bar being rotatable;
a second tire sensing rod in perpendicular orientation with the elongate bar, and coplanar with and disposed on the same side of the elongate bar as the first tire sensing rod, the second rod affixed to the slidable housing, the second rod containing a plurality of sensors to measuring the diameter of the tire across the width of the entire tire;
a sensor within the slidable housing for providing indicia of the location of the second tire sensing rod on the elongate bar;
a processing means electrically connected to the sensor to sense the position of the sensor; and
a digital means to display the position of the sensor electrically connected to the processing means.
REFERENCES:
patent: 4216584 (1980-08-01), Meissner et al.
patent: 4607436 (1986-08-01), Clay
patent: 5465501 (1995-11-01), Rogler
patent: 5694697 (1997-12-01), Curtis
Capps Rick
Paulsen Craig
Bennett G. Bradley
Skinner Sutton Watson & Rounds
Skinner, Sutton, Watson & Rounds
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