Geometrical instruments – Straightedge type – Square and pivoted straightedge
Reexamination Certificate
2000-11-28
2003-04-29
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straightedge type
Square and pivoted straightedge
C033S471000, C033S495000
Reexamination Certificate
active
06553676
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to measuring instruments. More particularly, this invention relates to a protractor that permits a user to quickly and easily describe and define a wide variety of angular measurements.
BACKGROUND OF THE INVENTION
Protractors are well known and are used in a variety of fields and industries. For example, protractors are often used by school children who are learning how to define and a describe angular measures and to draw lines, shapes and figures that incorporate these measurements.
A typical prior art protractor
10
is shown in FIG.
1
A. The prior art protractor
10
includes a horizontal member
12
coupled to a semi-circular member
14
that substantially circumscribes one side of the horizontal member
12
. At the center of the horizontal member
12
is a center marking
16
which is used as a starting point for angular measurements. Along the outer edge
23
of the semi-circular member
14
are a plurality of radial markings
18
that are used to indicate the size, in degrees, of the particular angle relative to zero line
20
of the horizontal member
12
.
Although such prior art protractors are useful, they have a number of shortcomings. For example, users in general, and particularly children, often wish to not only determine the magnitude of certain angles, but also wish to draw lines that will describe or define those angles. In the case of the prior art protractor shown in
FIG. 1A
the zero degree line
20
is offset from the inner edge
25
of the horizontal member
12
preventing the user from drawing one of the two lines necessary to describe an angle. Additionally, there is no second straight edge that can be used to describe the second line. For this reason, the user must use a second instrument, such as a ruler, to describe these lines. Because multiple instruments are required for this task, however, the accuracy of any angular definition can be diminished during the removal and/or placement of the instruments to be used in describing the angle. Additionally, the prior art protractor
10
shown in
FIG. 1
typically has a very flat surface which can be especially difficult to grip and keep in a fixed position when making an angular measurement. This can be an especially difficult problem for young children, who have smaller hands and less developed coordination than an average adult.
A second prior art protractor is shown in FIG.
1
B. The second prior art protractor
110
includes horizontal and semi-circular members
112
and
114
respectively, in a similar arrangement as shown in FIG.
1
A. Similarly, the second prior art protractor
110
includes a center marking
116
and radial markings
118
along the outer edge
123
of the semi-circular member
114
. The second prior art protractor
110
also includes a lever arm
125
that rotates about the center marking
116
via a pin-hole combination
127
. The lever arm
125
serves as a guide that allows a user to more accurately define the angle being measured.
This arrangement also has disadvantages, however. For example, due to the pin-hole combination
127
of the second prior art protractor
110
, the protractor
110
must have a zero line
120
that is offset from the inner edge
129
of the horizontal member
112
. Because the zero-degree line is offset, a user cannot draw a complete and unbroken zero line without moving the protractor
110
. Additionally, because the center marking
116
is offset from the inner edge
129
of the horizontal member
112
, the user is unable to draw a second line along the lever arm
125
to the center marking
116
without moving the protractor.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a protractor that permits a user to define and describe a variety of angles and the starting and ending edges thereof with a single instrument.
It is a further object of this invention to provide an improved protractor that permits a user to accurately define a variety of angular measurements.
It is yet another object of this invention to provide a novel protractor that can easily be gripped by a user without affecting the accuracy of any angular measurements being made.
It is still another object of the invention to provide a novel protractor that enables a user to draw a complete angle and the point where the two outer lines of the angle intersect, wherein the corner created by the intersection of the two lines is always visible and accessible.
In accordance with these objects of the invention, an improved protractor is provided comprising a frame and an arm. The frame includes a first substantially straight edge and a circular track which is engaged with a concentric channel located on one side of the arm. The arm also includes at least one straight edge which is used to define one of the two boundaries of an angle. The combination of the track and channel permit the user to rotate the arm about an axis that is substantially orthogonal to both the arm and the frame, allowing the user to define a variety of angles between the edges on the frame and the arm. The arm is also provided with a gripping surface that allows the user to hold the protractor without affecting the measurement of the appropriate angle.
These and other objects, advantages and features of the invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings described below.
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Web page from school.fiskars.com/classroom/cool_tools/protactor/protactor.html, Nov. 2, 2000.
Barnard David E.
Boudreau Cory R.
Carlson Christopher Robert
Rindy Ryan W.
Roberts Sheldon
Alterra Holdings Corporation
Foley & Lardner
Fulton Christopher W.
Jagan Mirellys
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