Information
-
Patent Grant
-
6397480
-
Patent Number
6,397,480
-
Date Filed
Thursday, July 6, 200024 years ago
-
Date Issued
Tuesday, June 4, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Burns, Doane, Swecker & Mathis, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 030 451
- 030 457
- 030 458
- 030 459
- 030 461
-
International Classifications
-
Abstract
A pencil sharpener (10) is disclosed as including a body (12) with a hole (22) for receiving an end of a pencil, a cutting blade (24) secured to the body (12) for sharpening the pencil, and a stopper (30) movable relative to the body (12) to vary the length of the end of the pencil which may be received into the hole (22).
Description
BACKGROUND OF THE INVENTION
This invention relates to a mechanism for sharpening a writing instrument, e.g. pencil, and in particular such a sharpening mechanism in which the length of the sharpened end of the writing instrument which may be inserted into the sharpening mechanism may be adjusted.
Pencil sharpeners have been made available for a very long period of time. While various modifications have been made to the outward appearance of such sharpeners to make them more aesthetically attractive, relatively few improvements have been made to the basic structure. Conventional pencil sharpeners include a generally conical insertion hole tapering from a broad outer entrance to a sharp inner end. This hole allows an end of a pencil to be inserted into the sharper, such that the pencil will be sharpened by a cutting blade secured to the sharpener when the pencil is rotated relative to, and moves into, the sharpener.
In one type of conventional pencil sharpeners, the inner end of the hole is not closed, such that the pencil may be caused to go on rotating relative to and moving into the insertion hole. The disadvantage of such an arrangement is that more than the necessary pencil may be cut away, or the user may not wish the pencil to be so sharp.
As an improvement, some pencil sharpeners are provided with a stopper at the inner end of the insertion hole so as to limit the inward movement of the pencil relative to the sharpener. By way of such an arrangement, once the pencil has proceeded to abut the stopper, further rotation thereof will not bring about any further inward movement of the pencil, so that no further pencil will be cut away. A disadvantage associated with such an arrangement is that the pencil sharpener cannot sharpen the pencil to a degree of sharpness which is up to the requirement of the user.
As yet a further improvement, some conventional sharpeners provide two insertion holes, each with a cutting blade, yet one without a stopper and one with a stopper. Not only does such an arrangement increase the cost of production, this type of pencil sharpeners also suffers from the shortcoming that basically only two degrees of sharpness are allowed.
It is thus an object of the present invention to provide an improved mechanism for sharpening an writing instrument in which the above shortcomings are mitigated, or at least to provide a useful alternative to the public.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a mechanism for sharpening a writing instrument, which mechanism including a body member with a hole adapted to receive an end of said writing instrument, a cutting blade secured to said mechanism and adapted to sharpen said writing instrument, wherein said mechanism further includes a stopper movable relative to said body member to vary the length of said end of said writing instrument receivable into said hole.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will now be described, by way of an example, and with reference to the accompanying drawings, in which:
FIG. 1
is a perspective view of a pencil sharpener according to the present invention;
FIG. 2
is an exploded view of the pencil sharpener shown in
FIG. 1
;
FIG. 3
is a front view of the pencil sharpener shown in
FIG. 1
;
FIG. 4
is a top view of the pencil sharpener shown in
FIG. 1
;
FIG. 5
is a bottom view of the pencil sharpener shown in
FIG. 4
;
FIG. 6
is a left side view of the pencil sharpener shown in
FIG. 4
;
FIG. 7
is a right side view of the pencil sharpener shown in
FIG. 4
;
FIG. 8
is a rear view of the pencil sharpener shown in
FIG. 4
;
FIG. 9
is a cross-sectional view of the pencil sharpener taken along the line A—A in
FIG. 3
;
FIG. 10
is a cross-sectional view of the pencil sharpener taken along the line B—B in
FIG. 4
; and
FIG. 11
is a cross-sectional view of the pencil sharpener taken along the line C—C in FIG.
3
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2
show a pencil sharpener according to the present invention, generally designated as
10
. The pencil sharpener
10
includes a body
12
which is secured to an end cap
14
by two screws
16
. The body
12
includes a front circular plate
18
with a circular entrance
20
, which leads into a conical hole
22
, which may be seen more clearly in FIG.
9
. As in conventional pencil sharpeners, a cutting blade
24
is secured by a screw
26
to the body
12
, so that when an end of a pencil is inserted into the hole
22
, rotation and moving in of the pencil relative to the body
12
will cause the pencil to be cut and sharpened by the blade
24
.
As can be seen clearly in particular in
FIG. 2
, the pencil sharpener
10
includes a knob
28
associated with a stopper
30
. A lower end
32
of the knob
28
is received with a cavity
34
of the end cap
14
, and a ring
36
sits on the end cap
14
, so that the knob
28
may rotate relative to the end cap
14
. The inner surface
38
of the ring
36
is threaded. In addition, the knob
28
includes a spindle
40
whose outer surface is threaded. The stopper
30
includes a stopping surface
42
. The lower part of the stopper
30
is provided with internal threads
44
and external threads
46
. The lower part of stopper
30
is received within a cavity
48
between the spindle
40
of the knob
28
, and the inner surface
38
of the ring
36
of the knob
28
, in such a way that the internal threads
44
of the stopper
30
mesh with the spindle
40
, and the external threads
46
mesh with the threads on the inner surface
38
of the ring
36
. It should be understood that although there are the two threaded engagements between the knob
28
and the stopping member
30
, i.e. the engagement between the spindle
40
and the internal threads
44
of the stopper
30
on the one hand, and the engagement between the external threads
46
of the stopper
30
and the threads in the inner surface
38
of the ring
36
on the other hand, one such engagement will suffice for the purpose of the present invention.
The upper part of the stopper
30
is in the form of a generally rectangular prism, and is received within a channel
50
formed by a guiding member
52
, which guides the movement of the stopper
30
relative to the body
12
. By way of such an arrangement, rotation of the knob
28
will cause the stopper
30
to translationally move relative to the body
12
between a first position (as indicated by P
a
in
FIG. 9
) in which the stopping surface
42
is at or lower than (in the sense of
FIG. 9
) the sharp end of the hole
22
, and a second position (as indicated by P
b
in
FIG. 9
) which is above (again in the sense of
FIG. 9
) the end of the hole
22
. When the stopping surface
42
is in position P
a
, the pencil sharpener
10
will function as one with no stopper. When the stopper
30
is moved by the knob
28
such that the stopping surface
42
is at P
b
, the end of the pencil inserted into the hole
22
will abut the stopping surface
42
, so as to limit the length of the end of the pencil which can be inserted into the hole
22
. Such an arrangement may thus vary the length of the end of a pencil which can be inserted into the hole
22
. A further feature of the present invention is that the stopping surface
42
may be positioned anywhere between P
a
and P
b
, so that the degree of sharpness of the sharpened pencil may be selected by the user.
Claims
- 1. A mechanism for sharpening a writing instrument comprising a body member with a hole adapted to receive an end of said writing instrument, a cutting blade secured to said mechanism and adapted to sharpen said writing instrument, and a knob member and a stopper threadedly engaged with each other, wherein said knob member is movable only rotationally relative to said body member about a longitudinal axis of said body member, and wherein rotation of said knob member causes said stopper to slidingly move along an axis which is substantially parallel to said longitudinal axis of said body member to vary the length of the end of a writing instrument receivable into said hole.
- 2. A mechanism according to claim 1 wherein said knob member and said stopper are movable relative to each other.
- 3. A mechanism according to claim 1 wherein said stopper includes an end with an outer threaded portion which is engaged with a threaded portion in at least part of an inner surface of said knob member.
- 4. A mechanism according to claim 1 wherein said stopper includes an end with an inner threaded portion which is engaged with a threaded portion in at least part of a spindle member of said knob member.
- 5. A mechanism according to claim 1 wherein said stopper includes a substantially rectangular prismatic end translationally movable relative to a guiding member.
- 6. A pencil sharpener including a mechanism according to claim 1.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4506716 |
Hayashi |
Mar 1985 |
A |
4620370 |
Zownir et al. |
Nov 1986 |
A |
4755074 |
Roberts |
Jul 1988 |
A |