Information
-
Patent Grant
-
6606796
-
Patent Number
6,606,796
-
Date Filed
Friday, February 2, 200123 years ago
-
Date Issued
Tuesday, August 19, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Michael Best & Friedrich LLC
-
CPC
-
US Classifications
Field of Search
US
- 033 2702
- 033 2703
- 033 27031
- 033 27032
- 033 27033
- 033 472
- 033 484
- 033 485
- 033 492
- 033 493
- 033 486
- 033 489
- 033 490
- 033 495
- 033 487
- 033 488
- 033 491
- 033 494
-
International Classifications
-
Abstract
A drawing tool comprising a protractor portion at one end and an elongated radius arm portion extending therefrom, with a pivot disc rotatably mounted in the tool, and an adjustable radius indicator slideably mounted in the radius arm portion, the pivot disc having an open circular pivot point and the adjustable radius indicator having means for automatically resisting unintended indicator movement.
Description
FIELD OF THE INVENTION
This invention relates to drawing tools and, more particularly, to multipurpose drawing tools enabling the user to draw circles, to draw and measure lines, to construct and measure angles, and to produce geometric constructions and patterns.
BACKGROUND OF THE INVENTION
There are numerous drawing tools available in the prior art for drawing circles, drawing and measuring lines, constructing and measuring angles, and producing geometric constructions and patterns. Generally, these devices do not provide clearly visible, direct views of vertex points through an open pivot point for drawing circles, constructing and measuring angles, and producing geometric constructions and patterns. Rather, the user must approximate the positioning of the device over the vertex point, impairing the accuracy of the positioning of circles drawn with the device, or the accuracy of the construction and measurement of angles.
Additionally, even where devices are provided which can be used in performing all of the above functions, the devices require numerous parts, which make them expensive to construct and easy to damage. Where the devices are provided with adjustable radius indicators, i.e., movable parts which must stay put once positioned, the prior art devices are slow and cumbersome to use, and can be inaccurate.
Accordingly, an object of the present invention is to provide a drawing tool which provides an open pivot point providing a direct view of vertex points on drawing surfaces positioned under the tool;
It is another object of the present invention to provide a simple, inexpensive and easy-to-assemble drawing device for drawing circles, drawing and measuring lines, constructing and measuring angles, and producing geometric constructions and patterns;
Yet another object of the present invention is to provide a drawing tool with a movable radius indicator which is accurate and will stay put once positioned without a separate locking mechanism which must be manipulated once the indicator is in the desired location; and
A still further object of the present invention is to provide a drawing tool having an elongated position for measuring and drawing lines and a protractor portion for measuring angles.
SUMMARY OF THE INVENTION
The present invention comprises a multi-purpose drawing tool including a protractor portion at one end and an elongated radius arm portion at the other end. An adjustable radius indicator, which is mounted in an elongated cavity for movement along the elongated radius arm portion, includes spring portions biased against the sides of the elongated cavity and pressure dimples riding in and engaging slots running alongside the elongated cavity to resist unintended indicator movement. The indicator rides in elongated slots in the bottom of the first member and along upstanding elongated ridges in the top of the first member. The drawing tool also includes dimples in its underside to prevent smudging of markings already on a drawing surface positioned below the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects, aspects and advantages of the invention will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings in which:
FIG. 1
is a top plan view of a multi-purpose drawing tool, including an adjustable radius indicator and a pivot disc, in accordance with the invention;
FIG. 2
is a bottom plan view of the tool of
FIG. 1
, with the adjustable radius indicator and pivot disc removed;
FIG. 2A
is a cross-sectional view of a portion of the tool illustrated
FIG. 2
, taken along lines
2
A—
2
A of
FIG. 2
;
FIG. 2B
is an enlarged cross-sectional view of a portion of the drawing tool along the inner edge of the bore receiving the pivot disc of the tool;
FIG. 3
is a top plan view of the tool of
FIG. 1
, with the adjustable radius indicator and pivot disc, as well as the linear and angular measurement markings removed;
FIG. 4A
is a top plan view of the bottom part of the pivot disc referred to above;
FIG. 4B
is a cross-sectional view of the pivot disc taken along lines
4
B—
4
B of
FIG. 4A
;
FIG. 4C
is a bottom plan view of the pivot disc referred to above;
FIG. 5A
is a top plan view of the top part of the pivot disc referred to above;
FIG. 5B
is a cross-sectional view of the top part of the pivot disc, taken along lines
5
B—
5
B of
FIG. 5A
;
FIG. 5C
is a bottom plan view of the pivot disc referred to above;
FIG. 6
is a bottom plan view of the top part of the adjustable radius indicator referred to above;
FIG. 6A
is a top plan view of the adjustable radius indicator referred to above;
FIG. 6B
is a cross-sectional view of the top part of the adjustable radius indicator taken along lines
6
B—
6
B in
FIG. 6
;
FIG. 6C
is a side elevation view of the top part of the adjustable radius indicator referred to above;
FIG. 7
is a top plan view of the lower part of the adjustable radius indicator referred to above;
FIG. 7A
is a bottom plan view of the lower part of the adjustable radius indicator referred to above;
FIG. 7B
is a front elevation view of the lower part of the adjustable radius indicator referred to above;
FIG. 7C
is a side elevation view of the lower part of the adjustable radius indicator referred to above;
FIG. 7D
is a cross-sectional view of the lower part of the adjustable radius indicator taken along lines
7
D—
7
D in
FIG. 7A
;
FIG. 8A
is a side elevation view of the adjustable radius indicator with the upper and lower parts assembled;
FIG. 8B
is a front elevation view of the adjustable radius indicator with the upper and lower parts assembled; and
FIG. 9
is a compass tool employing the pivot disc of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
A multi-purpose drawing tool in accordance with the present invention
10
is generally illustrated in FIG.
1
. Preferably, the body of the tool is made from a clear or opaque plastic. It is also preferable that the plastic be shatter-resistant, for durability and safety reasons.
The drawing tool has a body
11
including a protractor portion
12
at its proximal end, and an elongated radius arm portion
14
at its distal end. An elongated rectangular cavity
16
having opposite edges
15
and
17
is centered on the longitudinal axis of the radius arm portion. An adjustable radius indicator
18
which, as explained in more detail below, is designed to take advantage of the cross-sectional shape of radius arm portion
14
, is mounted for sliding motion in cavity
16
. Finally, a pivot disc
20
is rotatably mounted adjacent the proximal end of the tool, bridging the intersection
22
of the protractor portion and the radius arm portion of the device. Most notably, pivot disc
20
includes a open circular pivot point or hole
24
. As shown in this figure, a bore
44
is formed adjacent the proximal end of the tool at the center of the circle defined by the half-moon protractor portion, for receiving pivot disc
20
.
Protractor portion
12
is half-moon in shape, and projects beyond the lateral edges
26
and
28
of the radius arm portion. As shown, the protractor portion is marked off in 5° increments by a series of lines
30
printed along the outer edge
32
of the protractor portion. Every 15° is numbered just below these lines, so that the protractor bears degree markings from 15° to 165°, with the unmarked 0° and 180° positions at the bottom edge
34
of the protractor portion. A protruding pointer or spur
39
is provided along the outer edge
32
of the protractor portion opposite the 90° marking. Two complementary series of degree markings are provided, so that the user can measure angles beginning at 0° or at 180° from either one of the corners
36
and
38
of the protractor portion.
An integral radius arm portion
14
distally from the bottom edge
34
of the protractor portion. In the embodiment shown, the radius arm portion is approximately 5 inches in length, although it may be of any desired length. A series of metric system markings appears along edge
26
of the radius arm portion, while a series of English system markings appears along the edge
28
of the radius arm portion. Additionally, on the distal edge
40
of the radius arm portion, at its center, a protruding pointer or spur
42
(directly opposite spur
39
of the protractor portion) is provided to assist the user in aligning the tool with any straight line on a surface below the tool by positioning the tips of both spurs
39
and
42
on the line. Additionally, a hole
45
is provided just above spur
42
. This hole can be used to store the tool on a ring in a notebook ring binder.
The underside
46
of the drawing tool of
FIG. 1
, with the adjustable radius indicator
18
and the pivot disc
20
removed, is illustrated in FIG.
2
. Six dimples
52
a
-
52
f
are spaced along either side of the underside of the drawing tool to maintain the underside of the drawing tool even with the underside of the pivot disc
20
which also includes dimples on its underside (
82
a
-
82
d
), as discussed below in connection with FIG.
4
C. These dimples also minimize smudging of markings on the surface below the tool.
FIG. 2A
, which is an enlarged cross-sectional view taken along line
2
A—
2
A in
FIG. 2
, shows a pair of elongated slots
54
and
56
formed in the bottom surface
46
of the radius arm portion of the tool, spaced from and along the opposite elongated edges of the cavity. These slots establish a pair of elongated upstanding ridges
58
and
60
immediately adjacent elongated rectangular cavity
16
.
FIG. 2B
, which is an enlarged cross-sectional view of a portion of the drawing tool along the inner edge of bore
44
, shows integral annular shoulders
48
and
50
that encircle bore
44
, at the top and the bottom of the tool.
The top surface of the tool, again with the adjustable radius indicator
18
and the pivot disc
20
removed, is illustrated in
FIG. 3
, sans linear and angular measurement markings. This figure shows generally parallel upstanding elongated ridges
62
and
64
running along the edge of elongated cavity
16
, adjacent its opposite elongated edges. Ridges
62
and
64
and slots
54
and
56
cooperate with the radius indicator, as will be explained below.
Pivot disc
20
includes two interconnecting parts, a bottom part
70
and a top ring part
72
, as illustrated respectively in
FIGS. 4A-4C
and
5
A-
5
C. The bottom part and the top ring part are shaped and dimensioned to be press-fit and glued together.
Bottom part
70
, which is preferably made of the same plastic as the body of the tool, includes an outer circumference
74
that is at least slightly larger than the circumference of bore
44
and a central bore or open circular pivot point
24
, as referenced earlier. It also includes an inner annular lip
76
, with a ramped inner surface
77
, and a generally vertical annular surface
84
offset from the outer edge to define a flat annular band
80
. The bottom surface
78
of part
70
, illustrated in
FIG. 4C
, includes a series of four dimples
82
a
,
82
b
,
82
c
and
82
d
adjacent the outer edge of the part, spaced 90° from each other. In practice three or more such dimples may be used. Additionally, raised lines
84
are provided, extending from the outer circumference circular pivot point
24
to dimples
82
a
-
82
d
. These lines are visible from the top of the tool as user looks down through the pivot disc, thereby enabling the user to both visualize the absolute center of the pivot point opening at the intersection of the lines, and to line up the center of the pivot point opening with the vertex of perpendicular intersecting lines on a sheet of paper positioned below the tool (not shown). The dimples on the underside of the pivot disc help maintain the disc in place as it is pressed down upon the underlying surface by the user and, by minimizing points of contact to the underlying surface, the dimples also minimize smudging.
Top ring
72
is shown in
FIGS. 5A-5C
. The ring includes a central bore
86
with an inner annular surface
88
and an outwardly extending annular lip
90
along its circumference establishing an annular shoulder
92
(FIG.
5
B). Ring
72
is dimensioned so that its inner annular surface
88
will fit snugly around the outer annular surface
84
of bottom part
70
when the two parts are press fit together. It is preferred that the annular ring be made of the same shatter-resistant plastic as the rest of the tool, but that a coloring agent be added to make the ring translucent or opaque.
Pivot disc
20
is assembled to the tool by placing part
70
in bore
44
so that annular lip
76
projects upwardly resting on shoulder
50
in the underside of the tool (FIG.
2
B), and annular band
80
rides shoulder
48
. Once part
70
is in this position, ring
72
is positioned above the top surface of the tool, and pressed home onto part
70
so that the two parts are locked in a pressed fit and glued relationship with annular surface
94
of the ring abutting the inner portion of band
80
of the bottom part and lip
90
riding on annular ring
48
of the top of the tool (FIG.
2
A), leaving disc
20
free to rotate within bore
44
. Additionally, translucent or opaque ring
70
directs the user's eye to the disc, to facilitate its use.
Adjustable radius indicator
18
is made of two parts, an upper part
100
and a lower part
150
. Upper part
100
is illustrated in
FIGS. 6-6C
. Upper part
100
is generally rectangular in shape, with a top surface
101
, a bottom surface
103
, two generally parallel elongated outer edges
102
and
104
, and two generally shorter edges
106
and
108
perpendicular to edges
102
and
104
. The upper part also includes bores
66
and
68
at either end (
FIG. 1
) for receiving a marking instrument and drawing a circular line about pivot disc
20
or a straight line along cavity
16
. The upper part also includes elongated shoulders
111
with four pointer portions
110
at opposite ends of elongated edges
102
and
104
, so that they point outwardly from those lateral edges. Each pointer portion ends in a sharp tip
112
.
An elongated trough
116
is formed in the top surface
114
of upper part
100
and extends from end
118
to end
120
, as illustrated in FIG.
6
B. Thus trough has a generally flat bottom surface
122
and angled outer walls
124
and
126
. Bores
128
and
130
are provided along the central axis of the top part, adjacent ends
106
and
108
. These bores, which are intended to receive a pencil point that extends through to a drawing surface below the tool (not shown), are conically shaped at their bottom, as defined by the annular angled wall
132
.
Additionally, bores
134
and
136
are located along the central longitudinal axis of the adjustable radius indicator, spaced from edges
106
and
108
. Bores
134
and
136
are intended to receive upstanding pins
172
and
174
(discussed below in connection with lower part
150
) which project upwardly from the generally flat surface
122
of trough
116
. These pins help align and attach the the two parts of the adjustable radius indicator and, most importantly, act as handles to enable the user to move the indicator of the fully assembled tool.
As shown in
FIGS. 6A and 6B
, the base
105
of the top part has elongated outer edges
107
and
109
inwardly offset from elongated edges
102
and
104
. Generally oval relief slots
140
and
142
are provided in angled outer walls
124
and
126
intermediate ends
106
and
108
of the top part. The relief slots are positioned near edges
107
and
109
to define spring portions
111
and
113
along these edges. The relief slots and corresponding spring portions are biased outwardly to present engagement surfaces
115
and
117
. This arrangement permits the spring portions to flex inwardly as the adjustable radius indicator is positioned in elongated cavity
16
and then to present an outwardly directed spring bias against the inner edges
15
and
17
of the elongated slot to produce friction between the engagement surfaces and the inner edges of the elongated cavity as the indicator is moved within the cavity, automatically resisting unintended or inadvertent indicator movement. This design eliminates any need for a separate locking mechanism which would have to be manipulated once the indicator is in the desired location.
As shown in
FIG. 6C
, the bottom of upper part
100
includes an elongated transverse slot
144
extending across base
105
of the top part, leaving rectangular protruding portions
146
and
148
extending across the base at either end of the part. As explained below, these protruding portions cooperate with the lower part of the radius indicator to lock the indicator to the tool.
Lower part
150
of adjustable radius indicator
18
is shown in
FIGS. 7-7F
. This part is generally rectangular, having top and bottom surfaces
151
and
153
, ends
152
and
154
, and elongated outer edges
156
and
158
. The lower part is of a length corresponding to the length of transverse slot
144
in base
105
of upper part
100
to permit the lower part to fit snugly lengthwise in the slot. The width of the lower part is at least slightly greater than the width of elongated cavity
16
in elongated radius arm portion
14
of the tool to prevent the adjustable radius indicator from pulling out of the cavity once the indicator is assembled on the tool. Lower part
150
also includes a pair of upstanding elongated ridges
160
and
162
along edges
156
and
158
, and spacing dimples
164
and
166
centered on each of the elongated ridges.
Finally, lower part
150
includes a pair of upstanding pins (or handles)
170
and
172
which are generally hollow at blind bores
171
and
173
(to facilitate molding), and dimensioned at their respective bases
174
and
176
to fit snugly in bores
134
and
136
of upper part
100
. The pins are rounded at their tips
178
and
180
to facilitate molding and insertion in bores
134
and
136
in the upper part. The pins are also tapered at their top portions
182
and
184
so that when the user grasps these pins to use them as handles they are easier to grasp to move adjustable radius indicator along cavity
16
.
The adjustable radius indicator may be assembled to the tool by positioning the lower part
150
under the radius arm portion, with elongated ridges
160
and
162
of the lower part in elongated slots
54
and
56
of the radius arm portion. The upper part
100
is then positioned above the radius arm, with pins
170
and
172
opposite bores
134
and
136
in the upper part. The upper and lower parts are then pressed together to lock the adjustable radius indicator onto the radius arm portion in a fit having sufficient clearance to permit the adjustable radius indicator to slide within the elongated slot when the user moves it yet sufficiently snug to “brake” or automatically restrain the indicator to prevent unwanted movement once the indicator is set at the desired location. This snug fit and automatic resistance to indicator movement is aided by pressure dimples
164
and
166
in the lower part of the indicator. The fully assembled adjustable radius indicator (sans the radius arm portion) is shown in
FIGS. 8A and 8B
.
The drawing tool of the present invention may be used to draw an infinite number of perfect circles. In order to do so, the adjustable radius indicator typically is placed in the desired position with hole or circular pivot point
24
over either a dot on the drawing surface or the vertex point of an angle. Since the pivot disc is clear and has a through-opening at the pivot point, properly positioning the tool over the dot or vertex is particularly easy to accomplish. Next, the user presses down upon the pivot disc which contacts the drawing surface at its bottom dimples and remains in place on the surface while a pen or pencil is pressed with its point through one of the drawing holes in the adjustable radius indicator, with the drawing instrument resting on the drawing surface. The pen or pencil is then swung in an arc about the pivot disc to form a circle of the desired radius.
Many of the unique advantages of the drawing tool of
FIGS. 1-8
may be employed in other drawing tool configurations. For example, as shown in
FIG. 9
, a compass tool
200
comprising a large circular member
202
having a series of degree markings along its outer edge
204
may employ a pivot disc
206
of the same design as that shown in previous figures. Thus, pivot disc
206
is rotatably mounted at the center of compass
200
described above. Pivot disc
206
includes an open circular pivot point
208
. Thus, positioning of compass
208
is facilitated in the same way as positioning of the tool of
FIGS. 1-7
, namely, the clear pivot disc with its through opening makes clear visible positioning of the center hole over the desired location on the drawing surface particularly easy to accomplish. Once positioned, the user presses down upon the pivot disc which remains in place on the surface while the drawing instrument is pressed with its point through one of the groups of edge-beveled holes
210
a
-
210
d
, or moved about the circumference of one of the enlarged edge-beveled holes
212
a
-
212
d.
While the invention has been described in relation to a preferred embodiment, those skilled in the art may develop wide variations in structural details without departing from the principles of the invention. Accordingly, the appended claims are intended to be construed to cover all equivalents falling within the scope and spirit of the invention.
Claims
- 1. A drawing tool comprising:a first member adapted to rest against a drawing surface, the first member having an opening for receiving the tip of a drawing instrument for pressing through the opening onto the drawing surface; and a second member rotatably mounted in the first member, the second member having a circular pivot point comprising a through-opening, whereby the tool may be positioned on a drawing surface with the open circular pivot point of the second member aligned over a desired position appearing on the drawing surface and the second member pressed against the drawing surface while the first part is rotated thereabout with the drawing instrument against the drawing surface, to produce the desired markings on the drawing surface.
- 2. The drawing tool of claim 1 in which the first member is elongated and includes a protractor portion at one end of the member.
- 3. The drawing tool of claim 1 in which the first member includes an elongated rectangular cavity centered on the longitudinal axis thereof, and an adjustable radius indicator mounted in the elongated cavity, the adjustable radius indicator including means for automatically resisting unintended indicator movement.
- 4. The drawing tool of claim 3 in which the means for resisting unintended indicator movement comprises spring members biased against the inner edges of the elongated slot.
- 5. The drawing tool of claim 3 in which the means for resisting unintended indicator movement comprises pressure dimples for riding in and engaging slots alongside the elongated rectangular cavity.
- 6. The drawing tool of claim 1 in which the second member is clear or translucent and has at least one line, visible from the top of the second member, intersecting the circular pivot point.
- 7. The drawing tool of claim 1 in which the underside of the first member includes a plurality of dimples to minimize smudging of markings already on any drawing surface located under the drawing tool.
- 8. The drawing tool of claim 1 in which the second member includes dimples on the bottom surface thereof spaced about the circular pivot point to help resist unintended movement of the second member.
- 9. The drawing tool of claim 2 including spurs at opposite ends of the tool, one projecting proximally from the protractor portion and the other projecting distally from the distal end of the first member.
- 10. The drawing tool of claim 1 including a hole designed to permit a ring of a ring binder to pass therethrough.
- 11. The drawing tool of claim 3 including outwardly directed pointer portions on the lateral edges of the adjustable radius indicator.
- 12. The drawing tool of claim 3 in which the adjustable radius indicator includes handles in the form of upstanding pins.
- 13. The drawing tool of claim 12 in which a pair of upstanding pins are provided.
- 14. The drawing tool of claim 3 in which the adjustable radius indicator rides in elongated slots in the bottom of the first member and along upstanding elongated ridges in the top of the first member.
- 15. A compass tool comprising a circular member with holes in its surface and a pivot disc rotatably mounted at the center thereof, the pivot disc having a open circular pivot point comprising a through-opening.
- 16. The compass tool of claim 15 in which the pivot disc is clear or translucent and has at least one line visible from the top of the second member intersecting the circular pivot point.
- 17. The compass tool of claim 15 in which the underside of the circular member includes a plurality of dimples to minimize smudging of markings already on any drawing surface placed below the drawing tool.
- 18. The compass tool of claim 15 in which the pivot disc includes dimples on the bottom surface thereof spaced about the circular pivot point to help resist unintended movement of the second member.
- 19. A drawing tool comprising:a first member adapted to rest against a drawing surface, the first member having an opening for receiving the tip of a drawing instrument for pressing through the opening onto the drawing surface; the first member including an elongated rectangular cavity generally centered on the longitudinal axis thereof, and an adjustable radius indicator mounted in the elongated cavity, the adjustable radius indicator including means for automatically resisting unintended indicator movement; and a second member rotatably mounted in the first member, the second member having a circular pivot point comprising a through-hole; whereby the tool may be positioned on a drawing surface, with the through-hole of the circular pivot point of the second member aligned over a desired position appearing on the drawing surface and the second member pressed against the drawing surface while the first part is rotated thereabout with the drawing instrument against the drawing surface to produce the desired markings on the drawing surface.
- 20. The drawing tool of claim 19 including upstanding pins in the adjustable radius indicator to assist the user in moving the indicator.
US Referenced Citations (41)
Foreign Referenced Citations (1)
Number |
Date |
Country |
4244533 |
May 1993 |
DE |