GB2436814A

GB2436814A - Pencil sharpener

Info

Publication number: GB2436814A
Application number: GB0607116A
Authority: GB
Inventors: Timothy John Bradley
Original assignee: Helix Ltd
Current assignee: Helix Ltd
Priority date: 2006-04-08
Filing date: 2006-04-08
Publication date: 2007-10-10
Also published as: GB0607116D0

Abstract

Pencil sharpener 10 comprises a blade 14 and a body 12. The blade 14 is attached to the body 12 by a safety screw 16. This may have a head which cannot be engaged by a flat bladed or crosshead screwdriver (figures 2-7). Alternatively, it may be a one-way screw.

Description

2436814

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PENCIL SHARPENER

The present invention relates to pencil sharpeners.

5 According to a first aspect of the invention there is provided a pencil sharpener comprising a cutting member and a body wherein the cutting member is attached to the body by a safety screw.

Advantageously the cutting member cannot easily be removed from its 10 attachment to the body. This reduces the risk of the cutting member being able to be used as a weapon.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

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Figure 1 shows a pencil sharpener according to an embodiment of the invention;

Figure 6 shows the head of the screw provided in the pencil sharpener of 20 Figure 1;

Figures 2 to 5 and 7 show heads of screws provided in pencil sharpeners according to further embodiments of the invention; and

25 Figures 8 and 9 show heads of screws provided in prior art pencil sharpeners.

Referring to Figure 1, a pencil sharpener 10 comprises a metal body 12 and a cutting member 14. The cutting member is in the form of a 30 standard, metal, pencil sharpener blade. The blade 14 is attached to the body 12 by a safety screw 16. The body 12 has a screw receiving

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aperture (not shown) formed in it. The blade 14 also has a screw receiving aperture (not shown) formed in it. The safety screw 16 comprises a screw head 18 and a screw shaft (not shown). The screw shaft is arranged to be received in the screw receiving apertures of the 5 blade 14 and the body 12 in order to securely mount the blade 14 on the body 12 to form the pencil sharpener 10.

When the blade 14 is correctly mounted on the body 12 so that the pencil sharpener 10 is able to be used, a cutting surface 20 of the blade 14 is 10 provided in a safe position. This is because a portion of the body 12 of the sharpener 10 is arranged to be located close to the cutting surface 20 so that it is not possible to use the cutting surface 20 to cut objects in an unintended manner. In particular, it is not possible to use the blade as a weapon.

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The screw head 18 of the safety screw 16 is shown in more detail in Figure 6. For the purposes of this specification, a safety screw is a screw which comprises a screw head which is designed either:

20 i) to be unscrewed only with a non-standard screwdriver (i.e.

not by a standard flat bladed screwdriver or cross-head screwdriver); or ii) such that it cannot conveniently be unscrewed at all, i.e. a one-way screw.

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For comparison, Figure 8 shows a standard slotted screw head which can be unscrewed by a standard flat bladed screwdriver. Figure 9 shows a standard cross-head screw (also known as a cross-point or cruciform screw) which can be unscrewed by a standard cross-head screw driver 30 (e.g. a Phillips head screwdriver). The standard slotted screw and the standard cross-head screw are the most common designs of screws and

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therefore most screwdrivers are shaped to engage with these types of screws.

Referring to Figures 1 and 6, the screw head 18 of the safety screw 16 5 has a generally triangular shaped slot 22 which cannot engage with a standard (slotted or cross-head) screwdriver. Instead a special tool is required to unscrew this safety screw 16.

Advantageously, convenient unscrewing of the safety screw 16 is 10 prevented and thus convenient removal of the blade 14 from attachment to the body 12 is prevented. In particular, this can prevent use of the blade 14 as a weapon. This can be a particular problem in places such as schools where pencil sharpeners, intended for sharpening pencils, can conveniently become the source of a weapon if the screw attaching the 15 blade to the body of the pencil sharpener is easy to remove.

Figures 2, 3, 4, 5 and 7 show screw head designs according to other embodiments of the invention.

20 Referring to Figure 2, a screw head having two opposed circular cross-section slots 24, 26 requires a corresponding special screwdriver to unscrew it.

Referring to Figure 3, a hexagonal cross-section slot 28 is provided on a 25 screw head. In this embodiment, there is also a central projection 30 provided within the slot 28. This is a further security measure since a corresponding screwdriver in this embodiment is required to have a recess which corresponds in size and location to the projection 30 relative to the walls of the slot 28. If the screwdriver does not have such a recess, it 30 will not be able to engage with the head to turn the screw.

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Referring to Figure 4, a screw head comprises a Phillips pin head slot (similar to that shown in Figure 9). In addition, the screw head comprises a central projection 32 which, as with the Figure 3 embodiment, provides a safety feature since a corresponding screwdriver 5 is required to have a correspondingly located recess in order to unscrew this screw.

In other embodiments, recesses may be provided within the screw slots which are required to correspond to projections on screw drivers. In 10 these embodiments the main slot on the screw head will be required to be of a non-uniform shape since otherwise a standard screwdriver may be used to unscrew the screws.

Referring to Figure 5 a known, triple branch, Tri-Wing® design of screw 15 head is shown. This requires a corresponding non-standard screwdriver to engage with it.

Referring to Figure 7, a known, one-way slotted screw head design is shown. With this safety screw, advantageously a standard screwdriver 20 can be used to tighten the screw during manufacture. However there is no convenient way of untightening the screw since areas adjacent the standard slot are sloped are not allow engagement of a standard screwdriver with the walls of the screw head when an unscrewing motion is performed. In other embodiments, some pencil sharpeners may be 25 designed such that their blades can be replaced. The screw head of Figure 7 is particularly useful when the pencil sharpener is designed for single use i.e. it is intended to be discarded after the blade becomes blunt.

30 Various other modifications may also be made to the present invention without departing from the scope. For example, more than one screw

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may be used to attach a blade to a body to form a pencil sharpener and any one or more of the screws should comprise a safety screw.

It will be appreciated that projections (similar to those provided in the 5 embodiments of Figure 3 and Figure 4) may be provided in conjunction with the screw heads of any of the other embodiments. Also in other embodiments, the projections/recesses in the screw heads may not be provided centrally on the screw head - they may not even extend upwards from the screw head, instead they may extend into walls of the main slot 10 provided on the screw head. There may be more than one slot/projection in some embodiments. It will also be appreciated that any other nonstandard screw head shape can be used to form a pencil sharpener according to this invention.

15 In the described embodiment the pencil sharpener comprises a metal body. In other embodiments the pencil sharpener may comprise a plastic body or a body of any other suitable material. However the invention is particularly suited for implementation in pencil sharpeners comprising metal bodies because with plastic bodied pencil sharpeners it is possible 20 to insert a blade into the body of the pencil sharpener during moulding, thus removing the requirement for any screws at all.

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Claims

1. A pencil sharpener comprising a cutting member and a body wherein the cutting member is attached to the body by a safety screw.

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2. The pencil sharpener of Claim 1 wherein the safety screw comprises a screw head having a slot shaped such that it cannot be unscrewed by a standard flat bladed screwdriver or a standard cross head screwdriver.

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3. The pencil sharpener of Claim 2 wherein the safety screw comprises a one-way screw.

4. The pencil sharpener of any preceding claim wherein the safety 15 screw comprises a projection or recess arranged to engage with a corresponding recess or projection in a screwdriver.

5. The pencil sharpener of any preceding claim wherein the cutting member comprises a blade.

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6. The pencil sharpener of any preceding claim wherein the body comprises a metal body.

7. A pencil sharpener substantially as hereinbefore described with 25 reference to the any one or more of the accompanying drawings.