GB2232120A - Pencil sharpener - Google Patents

Abstract

A pencil sharpener (1) comprising a safety razor blade (28) held between two parts (4,6) of a housing unit having a plurality of holes (20, 22) therein of different sizes for pencils or pencil leads of respectively different sizes. The two housing parts slidably interengage by means of tongues (12,14) locating in grooves (8,10). The two housing parts may be made non-separable by including a detent (100. Fig. 7) in the tongue and groove arrangement. This renders the sharpener safe for use by children. <IMAGE>

Description

PENCIL SHARPENER This invention relates to a device for sharpening pencils, pencil leads, crayons and the like.

A known pencil sharpener typically comprises a housing unit having at least one hole, for the insertion of pencils and the like, and is fitted with specially designed blades. For example when a pencil is to be sharpened1 it is inserted into a hole in the housing unit and rotated against the cutting edge of the blade.

This action shaves a layer from its surface, and, due to the rotary motion of the pencil with repect to the blade, the shaved layer is removed in the form of a length of shaving. When some types of pencil lead are sharpened1 the shaved layer is removed in the form of a very fine dust. This is due to certain physical characteristics of the material from which such leads are made.

When using a pencil sharpener of the type described above, problems are often experienced when a blade becomes blunt. The correct type of blade must be obtained, and the removal and subsequent replacement of a blunt blade is normally effected by the release of a screw which secures the sharpening blade in place.

Although such blades are readily available, a blade of the correct size must be obtained from a specialised retail outlet. For many people such a simple device does not merit such an amount of time and effort.

Furthermore, when sharpening pencil leads for clutch pencils, drawing instruments and the like, the creation of dust is a disadvantage as it often becomes transferred onto the hands of the user. Serious problems may be encountered if the dust becomes transferred onto the drawing being produced.

Other known methods for sharpening pencil leads present similar problems. For example, abrasive paper still produces such dust when used to sharpen pencils.

It is also a disadvantage to need several separate sharpeners for keeping a variety of drawing equipment in good working order. Most known sharpener access holes will each enable the satisfactory sharpening of only pencils of substantially one particular size; as a result most hand-held sharpener units are only constructed to deal with one or two particular sizes of pencil, by having one or two blades and respective access holes therefor.

According to the present invention there is provided a pencil sharpener comprising a safety razor blade held between two parts of a housing having a plurality of holes therein of different sizes for pencils or pencil leads of respectively different sizes.

Preferred embodiments of the present invention are pencil sharpeners, for sharpening a selection of sizes of pencil to a satisfactory quality of point, that can accept standard and readily available safety razor blades that are either new or have become too blunt to be used for shaving a human face; furthermore, these pencil sharpeners have means for collecting dust produced when pencil leads and the like are sharpened; furthermore, it is possible to provide such pencil sharpeners with means for securing the razor blades in place in a non-releasable manner.

Two embodiments of the present invention will now be described by way of example with reference to the accompanying drawings wherein : Figure 1 is an exploded perspective view of a pencil sharpener embodying the present invention: Figure 2 is an exploded perspective view of the pencil sharpener shown in figure 1 where viewed from the opposite direction: Figure 3 is a plan view of the downwardly facing surface of the smaller housing unit which is obscured from view in figures 1 and 2: Figure 4 is a plan view of the larger housing unit shown in figures 1 and 2 when viewed from the downwardly facing side which is obscured from view in figures 1 and 2, and when the tray is removed; Figure 5 is a plan view of the larger housing unit shown in figures 1 and 2, but with the blade removed; Figure 6 is a perspective view of the assembled pencil sharpener shown in figures 1 and 2; and Figure 7 is a sectional view of a non-releasable detent means according to an embodiment of the present invention.

In a first embodiment of the present invention, the illustrated pencil sharpener, generally designated 1, comprises a larger housing part 4 and a smaller housing part 6 which combine to form a housing unit 2. The larger housing part 4 has a pair of grooves 8, 10 disposed along mutually opposite inwardly facing surfaces of a pair of raised ridges 5,7 which run along, and project perpendicularly from, mutually opposite sides of an upwardly facing surface 30 of the larger housing part 4, thereby forming respective upward extensions of each of the sides 9, 11. The smaller housing part has a pair of tongues 12, 14 disposed along mutually opposite side surfaces 13, 15.The tongues 12, 14 and grooves 8, 10 are configured to be mutually compatible, thereby providing for the insertion of the tongues 12, 14 into the grooves 8, 10 to enable the two housing parts 4, 6 to slide together, and hence effect interengagement therebetween.

Each housing part 4, 6 further comprises a respective pair of access holes 19, 20, 21, 22 to provide access to the sharpening edges 24, 26 of a blade 28. The smaller housing part 6 has a hole 19, 20 disposed in each of its two end surfaces 32, 34 adjacent respective opposite sides 13, 15. Extending inwardly of the holes 19, 20 are a respective pair of sharpening cavities 36, 38 each having a generally conical configuration, designed to receive the ends of pencils, pencil leads and the like, having a generally small diameter, therein. The larger housing part 4 also comprises a pair of holes 21, 22 wherein the holes are disposed in respective opposite end surfaces 37, 39 adjacent respective opposite sides 9, 11.Extending inwardly of the two holes 21, 22 are a respective pair of sharpening cavities 40, 42 each having a generally conical configuration, designed to receive the ends of pencils and the like, having a generally large diameter, therein.

Each of the sharpening cavities 36, 38, 40, 42 has a slit 44, 46, 48, 50 disposed along its length and adjacent the sharpening edges 24, 26 of the blade 28. A first pair of the slits 44, 46 open out into an upwardly facing surface 30 of the larger housing part 4 and a second pair of the slits 48, 50 open out into a downwardly facing surface 51 of the smaller housing part 6 respectively.

The larger housing part 4 further comprises a dust chamber 52 which is disposed in a lower portion thereof.

The dust chamber 52 is bounded by the sides 9, 11 and the ends 37, 39 of the larger housing part 4 and a tray 54 which is slidably insertable into guide grooves 56, 58, 60 formed in the inner surfaces of the sides 9, 11, and the end 37. When inserted into the guide grooves 56, 58, 60 the tray 54 constitutes a downwardly facing surface of the larger housing part 4 and effectively seals the chamber 52 to prevent the escape of lots of dust from the housing unit 2.

The larger housing part 4 has a seating projection 62 running longitudinally along, and projecting perpendicularly from, the upwardly facing surface 30 thereof; a buffer projection 64 disposed at one end of the upwardly facing surface 30 thereof; an indent 66 disposed at the opposite end of the upwardly facing surface 30 thereof; and a first pair of apertures 68, 70 disposed in the upwardly facing surface 30 thereof and in such a position that they communicate with, and are exactly aligned with, the second pair of slits 48, 50 when the tongues 12, 14 are fully inserted into the grooves 8, 10, which first pair of apertures 68, 70 communicate with the chamber 52.

The smaller housing part 6 has a groove 72 running longitudinally along its downwardly facing surface 51, so configured that upon the insertion of the tongues 12, 14 into the grooves 8, 10 it houses the seating projection 62 therein; a buffer projection 74 disposed at one end of the downwardly facing surface 51 thereof; an indent 76 disposed at the opposite end of the downwardly facing surface 51 thereof, and a second pair of apertures 78, 80 disposed in the downwardly facing surface 51 thereof and in such a position that they communicate with, and are exactly aligned with, the first pair of slits 44, 46 when the tongues 12, 14 are fully inserted into the grooves 8, 10, which second pair of apertures 78, 80 communicate with the outside of the sharpener housing unit.

The buffer projections 64, 74 and indents 66, 76 are so configured and located that they terminate the slide of the two housing parts 4, 6 as they are joined together, buffer projection 64 is shaped to be housed in indent 76, and buffer projection 74 is shaped to be housed in indent 64. As the two housing parts 4, 6 come into exact alignment the buffer projections 64, 74 abut facing surfaces of the respective indents 66, 76 and thereby prevent the two housing parts 4, 6 overshooting and coming out of alignment.

To assemble the sharpener for use, a blade 28 must first be inserted into the larger housing part 4 by placing the central slot 82 of the blade 28 over the seating projection 62 and dropping the blade onto the upwardly facing surface 30 thereof, thus preventing lateral movement of the blade 28 with respect to the upwardly facing surface 30 of the larger housing part 4. The tongues 12, 14 can then be inserted into the grooves 8, 10 and slid in the direction S shown in figures 1 and 2.

The sliding of the tongues 12, 14 into the grooves 8, 10 is eventually terminated by the action of the buffer projections 64, 74 on the indents 66, 76. Once the two housing parts 4, 6 have been brought into interengagement in this manner, the downwardly facing surface 51 of the of the smaller housing part 6 holds the blade 28 against the upwardly facing surface 30 of the larger housing part 4, and by this 'sandwiching' action the movement of the blade in the direction perpendicular to the upwardly facing surface 30 of the larger housing part 4 is prevented, thereby pressing the sharpening edges 24, 26 of the blade 28 against all of the sharpening slits 44, 46, 48, 50 in such a manner that the sharpening edges 24, 26 are positioned so as to partly close each of them.The tray 54 is then inserted into the guide grooves 56, 58, 60 to seal off the dust chamber 52 in order to prevent the escape of dust from the housing unit 2.

To sharpen a pencil, the correct sized access hole 19, 20, 21, 22 must be selected in order to give the best possible point on the pencil when it is sharpened. Such a hole would normally be the one having a sharpening cavity 36, 38, 40, 42 with internal dimensions that most closely match those of the end of the pencil to be sharpened. The pencil is then rotated in a clockwise direction, and a layer is shaved from the surface of the pencil, thus being removed in the form of a length of shaving. Each of the shaving cavities 36, 38, 40, 42 is orientated with its respective axis inclined at an angle to the upwardly facing surface 30 of the larger housing part 4 or the downwardly facing surface 51 of the smaller housing part 6 respectively, in order that the portion of the cone surface that is nearest thereto is parallel therewith.As a result of this orientation of the cavities 36, 38, 40, 42, the pencil end is sharpened into a conical shape.

If one of the sharpening cavities 40, 42 in the larger housing part 4 is selected for use, the shaving length produced upon the sharpening of the pencil exits from the larger housing part 4 through a respective one of the first pair of slits 44, 46 and then passes on through the corresponding one of the second pair of apertures 78, 80 in the smaller housing part to exit the sharpener 2 completely.

If one of the of the sharpening cavities 36, 38 in the smaller housing part 6 is selected for use, the shavings, which may be in the form of shaving lengths or in the form of a dust, exit from the smaller housing part 6 through a respective one of the second pair of slits 48, 50 and then pass on through the corresponding one of the first pair of apertures 68, 70 in the larger housing part 4 and thereby enter the dust chamber 52.

The dust chamber 52 can be emptied at some time convenient to the user. once the sharpener 1 has been assembled in the manner described above it is not necessary to separate the two housing parts 4, 6 until the the sharpening edges 24, 26 of the blade 28 become blunt. The two housing parts 4, 6 are easily separated by simply pulling them in opposite directions in order to slide the smaller housing part in the direction opposite to that of the arrow S. The blade 28 may then be replaced by simply lifting the blunt blade 28 out and inserting a sharper one. The sharpener 1 is subsequently re-assembled for use as described above.

If the sharpener 1 is intended for child use, or if it is a requirement that the blade 28, once inserted, is not capable of being removed, detent means can be disposed upon the tongues 12, 14 and grooves 8, 10; this enables a safety razor blade 28, that is either new or has become too blunt for shaving a human face, to be inserted into the sharpener 1 as described above; but, once the two housing parts 4, 6 have been assembled into interengagement, they are not seperable, and hence the blade can no longer be removed.

A second embodiment of the present invention comprises all of the features of the first embodiment, but with the addition of detent means 100. All like reference numerals used where describing the two embodiments refer to like features.

The detent means 100 comprises a pair of fin members 102, 104, each fin member having a fixed end 106, 108 and a distal end 110, 112, each being attatched at its respective fixed end 106. 108 to an internal downwardly facing surface 212, 214 of a respective one of the grooves 8, 10. The distal ends 110, 112 of the fins project downwardly from the surfaces 212, 214 of the grooves at an angle of approximately 450 and are flexible about the fixed ends 106, 108.

The fins are orientated in such a manner that each fin member 102, 104 has its distal end 110, 112 located closer to the buffer projection 64 than its respective fixed end 106, 108 is. Each fin member 102. 104 has a corresponding accomodating indent 216, 218 into which the fin member 102, 104 is forced as the tongues 12, 14 are inserted into the grooves 8, 10. Each accomodating indent 216, 218 is configured to house a respective fin member 102, 104 and is disposed in the downwardly facing internal surface 212, 214 directly adjacent the fixed end 106, 108 of the respective fin member 102, 104, and extends in such a direction, parallel to the arrow S, that the fin member 102. 104 may be accomodated therein, thus enabling the fin member 102. 104 to lie flush with the downwardly facing surface 212, 214 when it is forced into the accomodating indent 216, 218.

A pair of locking slots 250, 252 are disposed on respective upwardly facing surfaces 220, 222 of the tongues 12, 14 at positions corresponding to the locations of the accomodating indents 216, 218. Thus, when the two housing parts 4, 6 are fully engaged, the fin members are able to spring back out from the accomodating indents 216, 218 and enter the locking slots 250, 252. thereby preventing the separation of the two housing parts 4, 6.

In the above preferred embodiments, the pencil sharpener 1 is made from a plastics material. However, light metals and metal alloys could be used. Where a plastics material is used the two housing parts are preferably each moulded in one piece.

It is, therefore, possible by means of the present invention to provide a pencil sharpener. for sharpening a selection of different sizes of pencil to a satisfactory quality of point, that can accept standard and readily available safety razor blades; furthermore, said pencil sharpener has means for collecting dust produced when pencil leads and the like are sharpened; furthermore, it is possible to provide said pencil sharpener with means for securing said razor blade in place in a non-releasable manner. Such a pencil sharpener can. therefore, also be rendered safe for children to use.

It is possible to make many modifications to the present invention of which the above is merely a specific example. For example, it is possible to locate the detent means upon any convenient surfaces of the two housing parts. Furthermore. many alternative types of detent means will be available for use, including adhesives. It is also possible to provide additional indent means in the upwardly facing surface of the larger housing part or the downwardly facing surface of the smaller housing part, being shaped to correspond to the dimensions of a safety razor blade, in order to provide extra stability to the seating of the razor blade, thereby reducing lateral movement of the blade with respect to the upwardly facing surface.

Claims (13)

Claims:

1. A pencil sharpener comprising a safety razor blade held between two parts of a housing having a plurality of holes therein of different sizes for pencils or pencil leads of respectively different sizes.

2. A pencil sharpener as claimed in claim 1, wherein the two housing parts interengage with each other through respective tongues and grooves.

3. A pencil sharpener as claimed in claim 1 or 2, wherein a larger one of the two housing parts has at least one relatively large hole for at least one relatively large pencil, the smaller housing part having at least one relatively small hole for a relatively small pencil or pencil lead.

4. A pencil sharpener as claimed in claim 3, wherein the larger housing part has a second, intermediate size of hole, for an intermediate size of pencil.

5. A pencil sharpener as claimed in claim 4, wherein said hole in the smaller housing part is for a small pencil and the smaller housing part has a second hole for a pencil lead.

6. A pencil sharpener as claimed in any preceding claim, wherein at least one of the housing parts has at least one slit aperture for shavings to exit the sharpener.

7. A pencil sharpener as claimed in any preceding claim, wherein at least one of the housing parts has a removable tray for removal of shavings.

8. A pencil sharpener as claimed in claim 7, dependent on a combination of at least claims 3 and 6, wherein the slit aperture is in the smaller housing part and the tray is part of the larger housing part, whereby the slit can pass shavings from a relatively large pencil and the tray can permit removal when desired of shavings from a relatively small pencil or from a pencil lead.

9. A pencil sharpener as claimed in claim 8, wherein shavings from the smaller housing part are passed through at least one aperture in the larger housing part into a storage cavity disposed therein.

10. A pencil sharpener as claimed in any preceding claim, wherein detent means is provided for securing the two housing parts together.

11. A pencil sharpener as claimed in claim 10, wherein the detent means is non-releasable.

12. A pencil sharpener as claimed in claim 10, wherein the detent means is releasable.

13. A pencil sharpener substantially as described herein with reference to the accompanying drawings.