Geometrical instruments – Straightedge type – Plural straightedges – relatively moveable
Reexamination Certificate
2001-07-12
2002-10-01
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Straightedge type
Plural straightedges, relatively moveable
C033S0010DD, C033S027030
Reexamination Certificate
active
06457247
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a protractor with an auxiliary ruler, and more particularly to a protractor having a clear auxiliary ruler detachably and rotatably connected thereto. The auxiliary ruler could be turned relative to the protractor to align an indicating line on the ruler with one of the angle marks on the protractor, so that children could read the degree of an angle being measured or to draw a line corresponding to the measured angle with the help of the auxiliary ruler.
FIG. 1
shows a conventional protractor
10
that is a transparent semi-circular plate provided with marks
101
to indicate 180 degrees of angles. To measure an angle, the protractor
10
is laid on a surface of an angle to be measured with one of the marks
101
aligned with an edge of the angle, so that a degree of the angle could be read from the protractor
10
. The conventional protractor
10
of
FIG. 1
is not suitable for use when the angle to be measured is on a rather small figure, because the marks
101
are provided along an arced edge of the protractor
10
and would locate beyond an area covering the angle to be measured. A user could only determine an approximate degree of the measured angle according to an invisible line extended from a closest mark
101
toward the center of the circle on the protractor
10
. The degree of angle so determined is not perfectly accurate.
Moreover, the conventional protractor
10
of
FIG. 1
is only suitable for measuring an angle shown on a plane drawing or on a plane surface of an article, as shown in
FIG. 2
, and could not be used to measure an angle on a three-dimensional object, such as a polygonal column, a pyramid, etc.
When the conventional protractor
10
is used to draw an angle on a plane, the draftsman needs to make a mark on the drawing to align with a mark
101
on the protractor
10
showing a desired degree of angle, and then draws a line connecting the mark and an origin of measurement to obtain a wanted angle. The conventional protractor
10
is therefore not so convenient in use.
It is therefore tried by the inventor to develop a protractor with an auxiliary ruler that eliminates the drawbacks existing in the conventional protractor and is particularly useful in helping children to quickly and easily measure, draw or read an angle and learn the meaning of angle.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a protractor with an auxiliary ruler, wherein the protractor is a semi-circular plate provided at a center of circle with a through hole, so that a clear auxiliary ruler having a length close to a diameter of the protractor is detachably and rotatably connected to the protractor at the through hole. With an indicating line on the auxiliary ruler and degree marks on the protractor, the protractor of the present invention may help children to read an angle of an article being measured or to draw a line indicating an angle corresponding to a mark on the protractor, enabling children to easily understand the meaning of “angle” and to learn to use angles.
Another object of the present invention is to provide a protractor with an auxiliary ruler detachably attached to the protractor, so that the auxiliary ruler could be removed from the protractor for use alone. The auxiliary ruler is provided with a plurality of equally spaced through holes. A user may use two pens along with the separated auxiliary ruler to draw circles and arcs. Children may be guided in such drawing activities to understand meanings of center of circle, radius, diameter, circumference, etc.
REFERENCES:
patent: 346519 (1886-08-01), Tybjerg
patent: 1576800 (1926-03-01), Tibony
patent: 2042031 (1936-05-01), Watson
patent: 2104515 (1938-01-01), Golden
patent: 2612690 (1952-10-01), Cotton
patent: 2857674 (1958-10-01), Feldhake
patent: 2892586 (1959-06-01), Graham
patent: 2904885 (1959-09-01), Wood, Sr.
patent: 3263334 (1966-08-01), Mutter
patent: 3693261 (1972-09-01), Moore
patent: 5117560 (1992-06-01), Nevins
patent: 5205045 (1993-04-01), Liu
patent: 5408753 (1995-04-01), Hong
patent: 5588218 (1996-12-01), Barry et al.
patent: 6405443 (2002-06-01), Thorn et al.
Bednarek Michael D.
Bennett G. Bradley
Shaw Pittman LLP
Youth Toy Enterprise Co. Ltd.
LandOfFree
Protractor with an auxiliary ruler does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Protractor with an auxiliary ruler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protractor with an auxiliary ruler will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2984645