GB2035910A - Pencil sharpener - Google Patents

Abstract

Sharpener assembly 8 is rotatably mounted in casing 1, which is closed at one end by a sliding cap 2 and at the other by a removable lid 3. Movement of the cap 2 on the casing 1 against spring 10 rotates the assembly 8, so that it sharpens a pencil 17 inserted into it through a slot 33 in the cap 2 and an aperture in the casing 1. <IMAGE>

Description

SPECIFICATION Apparatus for sharpening pencils or pencil leads THIS INVENTION relates to apparatus for sharpening pencils of the kind comprising a lead encased in a wooden body or for sharpening, i.e. pointing leads of pencils of the propelling or clutch type. Pencils of the kind first mentioned and herein referred to as "wood-encased" and the leads of pencils of the propelling or clutch type are herein referred to as "unencased".

The best way of producing an accurate conical tip on wood-encased pencils or on unencased leads is by means of a straight or curved cutting edge which is rotated around the conical generated surface of the pencil point or lead tip. Accordingly, either the pencil or lead must rotate relative to the cutting edge or the cutting edge must rotate relative to the lead or pencil. In conventional cheap pencil sharpeners the pencil is rotated manually relative to the cutting edge, but in the more elaborate sharpening machines a heli cally toothed cutter having a number of cutting edges is rotated after.the fashion of planetary gearing and simultaneously orbits around the pencil point or lead tip. A rotary movement must be produced for both kinds of sharpener.

German Patent Specification 2 51 3 051 discloses a container or canister type pencil sharpener in which a sharpener element is fixedly mounted in a container adapted to receive shavings and lead debris and mounted for longitudinal movement in a sleeve. The container is mounted resiliently relatively to the sleeve and in its normal position covers the pencil-receiving aperture communicating with the sharpener, but after the inner container has been moved, the sharpener aperture can be moved into registration with a similar aperture in the outer sleeve to open the aperture leading to the sharpener. The pencil or lead must be rotated in a sharpener of this kind and for anatomical reasons can be rotated only through part of a complete revolution at a time.

Sharpening machines have long been known (e.g. from German Patent Specification 701,636) wherein an inclined straight or helically toothed cutter is rotated by a hand crank acting via intermediate planetary gearing and orbits around the pencil tip. Machines of this kind are very expensive to produce and cumbersome and complicated in operation. To sharpen a pencil or lead, a collet or the like must be moved axially against the force of a spring and the collet jaws opened. The collet must remain in this position until the pencil or lead which it is required to sharpen has been pushed through the collet and is in contact with the inclined cutting edges of the cutter.

Only then can sharpening proceed by the hand crank being rotated. Upon the completion of sharpening the collet must be opened for the sharpened pencil to be removed.

It is an object of the invention to provide apparatus for sharpening wood-encased pencils or for sharpening unencased leads which is of simple construction and very simple to operate. It is another object of the invention to provide such an apparatus in which the lead or pencil is so guided during the sharpening operation that no lateral forces likely to break the sensitive tip are produced during sharpening.

It is another object of the invention to provide such an apparatus which can be made to be of very small dimensions so that the same can be disposed in a container also adapted to collect shavings or the like.

According to the invention there is provided an apparatus for sharpening pencils or for pointing leads and including a body having a bore for guiding a pencil or lead and a mechanical drive for transmitting a movement to a cutting or pointing element, such element being mounted for rotation in said body around the tip of the pencil or lead, and in which an actuating element mounted for limited movement in two opposite directions in said body is arranged to be in driving connection with the sharpening element in one direction of movement of said actuating element and out of driving engagement with the sharpener element in the opposite direction of movement of said actuating element.

Embodiments of the invention are described below by way of example with reference to the accompanying drawings in which: Figure 1 is a longitudinal section through a pencil sharpener embodying the invention, the sharpener element not being shown in section, Figure 2 shows the sharpener element together with a one-way clutch associated therewith, the latter being shown in section; Figure 3 is a view in cross-section through the casing with the sharpener element assembled; Figure 4 shows another simplified sharpener element with associated clutch; Figure 5 shows the sharpener element of Fig. 4 and the components of its clutch; Figure 6 is a longitudinal section through apparatus embodying the invention, in the form of a sharpener. for unencased pencil leads, having a step-up transmission; Figure 7 is a perspective view of the complete sharpener of Figs. 1 to 3;; Figure 8 is a plan view of the sharpener of Fig. 7 with a closure slide removed; Figure 9 is a plan view of the closure slide of the sharpener of Fig. 7; and Figure 10 is a partial section view through a pressing cap of the sharpener of Fig. 7 with the closure slide fitted.

The preferred embodiment shown in Fig. 1 is a pencil sharpener having a container and embodied by a casing 1, pressing cap 2 and cover cap 3. A sharpener element 4 is rotata bly mounted inside casing 1 and is connected to a drive rod 5 acting as a rack and engaging with a driving wheel 6 secured to element 4, the driving connection to the element 4 being by way of a one-way directional clutch 7. As can be seen in Fig. 1, the clutch 7 is a coiled spring clutch 9. A spring 10 is disposed between the casing 1 and the cap 2, the items 1, 2 being adapted to move relatively to one another.

The container 11 is formed directly on the sharpener element 4 in the casing 1 and the drive elements are received in a closed compartment 1 2. The element 4 is secured axially in casing 1 by means of a catch cone 1 3 which may be adapted to operate after the fashion of a barb, allowing insertion of the element 4 into an aperture in an intermediate wall of the casing, but preventing subsequent removal of the element, the aperture defining a bearing it which the element 4 is supported for rotation. Mounted around entry aperture 14 is a guide flange 1 5 having a bore 1 6 of a diameter corresponding to that of the pencil 17. A stop pin 18 guided in a groove 19 serves to limit lengthwise movement of the cap 2 relatively to the casing 1.The cover cap 3 is arranged to be readily removable at will from body 1 so that shavings and lead debris can be emptied out, and so that access can be had to the sharpener element. The sharpener element should be readily accessible when mounted in the casing so that any pieces of pencil or lead which break off can be removed. Annular walls 20, 21 are so dimensioned as to abut one another so as to limit relative movement of parts 1 and 2, in the sense to compress the spring 10 to an extent such as to prevent binding of spring 1 0.

Fig. 4 shows a simplified sharpener element 4 which does not require a guide flange 1 5 (Fig. 1). The element 4 shown in Fig. 4 comprises a bearing journal 22 bounded by a shouldered cone 23 which merges in to the body 8 of the sharpener element. A passage 24 which extends transversely of the conical sharpener bore enables pieces of lead to be removed. This part is followed by a collar 25 serving as a second journal or abutment zone.

A stepped bearing shaft 26 is pressed into the body 8 of the sharpener element and has mounted on it a gear 27, the same merging into a collar 28. A coiled spring 29 is placed loosely on collar 28 and on the appropriate step of shaft 26, and forms an operative part of a one-way clutch as in the arrangement of Fig. 7.

Fig. 6 shows another embodiment which is in many respects similar to that of Figs 1 to 5 and in which like parts have like references.

However the embodiment of Fig. 6 differs mainly from the embodiments hereinbefore described by having a lead pointer 30, for unencased leads, instead of a sharpener 4; less force is required to drive the pointer 30 than sharpener 4 but the pointer must be driven faster. The required speed of rotation is obtained by utilising a step up transmission.

Thus drive rod 5 engages a pinion 31 on a shaft 32, rotatably mounted in a compartment 1 2 in the casing shaft 32 being parallel with the rotary axis of pointer 30, and a gear secured to shaft 32 meshes with a gear 6 secured to or integral with the body of pointer 3.

A one-way clutch may be omitted in the embodiment of Fig. 6, with the pointer 30 rotating in opposite directions during movement of part 2 relative to part 1 in opposite directions, or alternatively a one-way clutch, for example, similar to that described with reference to Figs. 2 to 5 may act between gear 6 and pointer 30 or between gear 31 and the gear which meshes with gear 6. A step up transmission such as that shown in Fig. 6, and incorporating such a one-way clutch may also be utilised where a rotary sharpening element, such as indicated at 4 in Fig. 2, is utilised in place of pointer 30.

In any of the embodiments described, the rod 5 may be a toothed rack having saw teeth and the driving gear 6 may be complementarily saw toothed. If desired, the saw-toothed rack and pinion 6 may be arranged to operate with a ratchet and pawl action, thus eliminating the need for a separate one-way clutch.

Figs. 7 to 10 show means for closing the pencil-receiving aperture of the actual sharpener. Cap 2 is formed with a slot 33 which has catch recesses 34 and in which a closure slide 35 can move. Between its cover plate 36 and the guide web 37 the slide 35 has a number of projections 38 which are adapted to the recesses 34 and can engage therein.

Near the slot 33 the cap 2 is formed with ridges 39 which prevent the slide 35 from dropping out. Alternatively, the slot 32, in cross-section perpendicular to the longitudinal direction in which the edges of slot 32 extend, may be of uniform substantially Tshaped, cross-section throughout its length, neglecting recesses 34, thus affording undercut portions along the longitudinal edges of the slot in the interior surface of the casing 2, and the closure slide 35 may have on the inner side of its cover plate 36, an elongate slide formation of complementary uniform Tshaped cross-section throughout its length, neglecting projections 38, thus affording, along each of its parallel longitudinal edges, guide webs which are received in said undercut portions of slot 33 and thus prevent the closure slide 35 from falling out.

In operation, the sharpener is held in the palm of the hand so that the cap 3 rests on the ball of the thumb with the bore 1 6 pointing upwards approximately in the direction of the extended thumb. The four fingers are then bent around the cap 2. The same is pressed to be moved on the casing 1 against the force of the spring 10, the rack 5 moving on the wheel 6. As can be gathered from Fig.

5, in conjunction with the other drawings, the friction between collar 28 and the inner diameter of the spring 29, during the operative stroke of part 2 relative to part 1 causes spring 29 to bind more tightly around collar 28, thus increasing the friction still further so that the spring engages tightly with the collar 28 and by a similar effect also engages tightly with the second collar on the shaft 26 and thus transmits the rotation to the sharpener 8.

When the manual pressure on the cap 2 is then released, the spring 10 causes part 2 to effect a return movement relative to part 1, to return the parts to their initial position, the gear rotating in the opposite direction. When the gear rotates in said opposite direction, the friction between spring 29 and collar 28 and shaft 26 tends to unwind so that the spring slips on collar 28 and shaft 26 and therefore allows the gear to rotate freely while the sharpener element 4 remains stationary. At each operative movement of the rack 5 the sharpener element 4 is rotated through a predetermined angle approximately equal to the distance which can be produced during sharpening with a simple manual sharpener.

The angle through which the sharpener element 4 is rotated can be varied as required by varying the transmission ratio. A simple way of doing this is to interpose a step-up transmission 31, in which event a lead pointer 30 can also be provided. Pressing the cap 2 once or twice is sufficient for the lead pointer 30 to point the leads of clutch-action pencils.

So that lead dust cannot drop out of the container 11, the slot 33 in the cap 2 is associated with a closure slide 35 which can be so pressed into catch recesses 34 in the normal position as to close the entry orifice of the sharpener element 4.

The mechanical drive according to the invention helps to provide ergonomically optimized operation of the sharpener device, the force required being much less than for the use of a conventional manual sharpener. The operative distance required for the novel sharpener is considerably less than for conventional crank type sharpening machines, so that sharpening takes less time.

Another considerable advantage is the simplicity of operation and the short movements required for sharpening are such as to require very little concentration and effort on the part of the operator. Operation is so simple throughout the whole sharpening procedure that the person using the sharpener finds it congenial to use.

More particularly when the sharpener according to the invention is used as a lead pointer, sharpening or pointing can be effected by a single stroke of the cap 2 relative to part 1 if a step-up transmission is provided.

Unlike the known lead pointers in which the lead of a clutch-action pencil with the lead clamped in it must be moved a number of times around the cutter axis of a wobbling movement, operation of the cap 2 for sharpening is very simple.

Claims (19)

1. An apparatus for sharpening pencils or for pointing leads and including a body having a bore for guiding a pencil or lead and a mechanical drive for transmitting a movement to a cutting or pointing element, such element being mounted for rotation in said body around the tip of the pencil or lead, and in which an actuating element mounted for limited movement in two opposite directions in said body is arranged to be in driving connection with the sharpener element in one direction of movement of said actuating element and out of driving engagement with the sharpener element in the opposite direction of movement of said actuating element.

2. An apparatus according to claim 1, in which a drive rod is connected to the actuating element and a driving gear is disposed on the sharpener element.

3. An apparatus according to claim 2, in which the drive rod is a toothed rack having saw teeth and engages with a saw tooth gear on the sharpener element.

4. An apparatus according to claim 3, in which the sharpener element is mounted rotatably in the casing and co-operates with a one-way clutch to form a unit.

5. An apparatus according to claim 4 in which a coiled spring clutch forms said oneway clutch disposed between the sharpener element and the driving gear.

6. An apparatus according to any of claims 2 to 5, in which a step-up transmission is provided between the rack and the driving gear.

7. An apparatus according to any of claims 1 to 6, in which the body is a casing and the actuating element is a pressing cap, the casing and cap being movable relatively to one another between two abutments against the force of a spring.

8. An apparatus according to claim 7 in which the casing is devised as a closable shavings container which can be closed by the closure cap and in which the sharpener element is mounted for rotation.

9. An apparatus according to claim 8, in that the casing is closable by said cover cap and an entry aperture in the casing and extending to the sharpener element is closable by a closure slide.

1 0. An apparatus according to claim 9, in which the pressing cap is formed with a slot in which said closure slide can move length wise.

11. An apparatus according to claim 10, in which the closure slide can engage by way of projections in catch recesses in the slot.

1 2. An apparatus according to claim 11 in which the closure slide has on the underside guide webs which engage below the wall of the pressing cap in the slot.

1 3. An apparatus according to any one of claims 7 to 12, in which the casing has a compartment adapted to receive the drive rod, the driving gear, the step-up transmission and the coiled spring clutch.

14. An apparatus according to claim 1 3 in which the spring has, extending around it, one annular wall in the pressing cap and another annular wall in the casing.

1 5. An apparatus according to any of claims 7 to 14 in which said casing has a guide bore adapted to the shape of the pencil or lead to be sharpened.

16. An apparatus according to any of claims 1 to 1 5 in which the sharpener element is rotatably mounted in a guide flange of said body.

1 7. A sharpener or the like according to claim 11 in that the slot in the pressing cap corresponds in width to the width of the pencil or lead to be sharpened.

1 8. Apparatus for sharpening encased pencils or for pointing unencased leads, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

19. Any novel feature or combination of features disclosed herein.