CA1104523A - Writing implement - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a writing implement comprising an outer casing, a coil spring disposed within the casing, an inner tube inserted through the coil spring and having a plurality of presharpened leads stored therewithin, and a capping member inserted over the open end of the inner tube. The front (writing) end of the inner tube is split into two clamping halves. The front end of the coil spring is formed into a hooked portion which slides along the slot formed between the clamping halves to allow the expelling and feeding of presharpened lead pieces into the.
clamping halves.

Description

11~4523 The present inven-tion is related to a writing and drawing pencll, in which ~he lead can ~e changed automatically and in which the leads are presharpened, thus requiring no sharpenLng.
Ever since the introduction o~ "presharpened" pencils in the market, there have been n~erous forms and kinds o~ such pencils in use. However, upon further investiga~ion, it is found that the construction o~ these pencils is not only very compli-cated, but also inconvènient in use and have many disadvantages.
The primary objective of the present invention is to provide a special construction in a presharpened pencil in order to ~acilitate writing, as well as to eliminate the disadvantages of the conventional presharpened pencils. ~ ~
The following are the advantageous characteristics~of the present invention: ` ~
1) The present invention adopts the "direct pressing"
method in which the user employs a one-handed operation to quickly push out or change the pencil lead for the purpose of writing.
The convenience and simplicity of this operatiQn have ne~er been shown. The previous presharpened pencils have never exhibited such desirable characteristics.~ -

2) While in use, the lead in the present pencil istightly pressed against the front end of the pencil so that there is no wobbling or vibrating, thus providing an extremely stable operation. ; ~ ~

3) When changing or refîlling the leads in the present pencil, the user's fingers dv not come in contact with the somewhat poisonous lead. This i5 one of the most outstanding ~ ~ -2- ~

~ , 5~Z3 advantages oE the present invention - to prevent the fingers from ge~ting dirty which is beneficial to the health of the users (e.g. students~.

4) In the present invention, the lead ~ections do not require lead holders or collars which means easier manu~acturing . and lower costs.

5) The present inven~ion allows the retractlon of an exposed lead into the pencil. Thus, there is no need for an additional cap to cover or protect the lead. I

6~ Since the construc-tion of the present invention is particularly simple, the parts can easily be made without fabri-cation by injection molding. As the manufacturing process is simplified, the cost is decreased to a large extent.
~; In addition to those described abov~, the other objectives~ effectiveness and features of the present invention ` are described in detail as follows~in conjunction with the appended drawings~
Figs. 1-5 are cross-sectional diagrams of an embodiment of the present invention, showing the various states of operation.
Fig. 6 is a cross-sectional diagram of an embodiment of the present invention, showing an inner tube being filled with lead.
I ~ Fig.~6A is a diagram of an embodiment of the present invention haviDg a spare tube for~the leads therein. ~
Fig. 7 is a three-dimensional sketch of the separaté
parts of an embodiment of the present invention.
Fig.~8 is a partlal cros6-sectional view of the inner tube of an embodiment of the present invention. ;

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11~45Z;i Fig. ~ shows the cross-sectional view along line AA in Fi~. 8.
As shown in Fig. 7, the automatic lead-changing, pre-sharpened writing and drawing pencil of the present invention consists of mainly an outer casing 10, an inner tube 20, a coil spring 30, and a capping memb~r for the inner tube 40. The outer casing 10 is made of a hollow round tube by a pipe-drawing ex-~rusion method, with the two opposite ends 11, 12 being tapered to form a generally conical shape. Each end has an appropriate opening 13 and 14 respectively, which opening has a smaller diameter than the casing 10. On outer casing 10, a circular groove 15 is provided near end 11 at about one third of the length of the casing 10. Two undercuts 16~ the purposes of which will be explained later, are also provided near end 11. The interior of tube 20 is provided with a channel 21 in which a plurality of leads 50 are stored. The foremost end of channel 21 is formed into a front tube channel 22 having a slightly smaller diameter.
The purpose for the smaller diameter of front tube channel 22 is to prevent the foremost one of the pencil leads 50 from passing therethrough, so that the leads 50 are held within tube 20. The other end of the tube channel 21 is made into a rear tube channel 23 (Fig. 2j for the purpose of adding new leads 50. The front end of inner tube 20 is enlarged to form conical head 24~ in which are cut two slip slots 26, 27, bisecting said enlarged conical head 24 into two crescent lead clamps 25. One slot 26 is ~--shorter ~about one hal:E of the length of one lead section which is usually about 1-1.5 cm long) and the other slot 27 is much longerj about five times the length oE slot 26. The closed end - 4 - ~
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of ~lot 27 is connected to slip channel 28, having a bottom wall and two side walls and formed by excavating in the direction o~
slot 27 on the wall o~ internal tube 20. The c~osed end of channel 28 has a slopi.ng bottom wall to facilitate the gliding of end 32 of coil spring 30 thereon. In addition, two protrusions ~:
29 are provided on the exterior surface o~ tube 20, at a distance of one third the length of tube 20 .from conical clamp 2S. The protrusions 29 are for pressing on coil spring 30 when the tube 20 is placed within outer casing 10 through coil spring 30. It is important to note that at the front end of spring 30, the last coil 31 constitutes a lead-pushing member 33 having a hooked tip 32 bent outwardly, i.e. away from the lnterior or tube 20.
Upon inserting inner tube 20 into outer casing 10 through coil spring 30, care is exercised so that tip 32 is aligned with~:slot .
27 and channel 28. When inner tube 20 is inserted through coil spring 30, the lead-pushing piece 33 at the front end of coil spring 30 is forced into slot 27, causing tip 32 to extend into the junction between tube channel 21 and front tube channel 22.
As a result, tip 32 can either effectively press onto or block against pencil lead 50. An eraser block 41 is inserted into capping member 40, having an interior surface 42. Capping member 40 is slipped over the end of inner tube~20 to:serve as an actuato r :
button during the use and:at the same time~as a cap in order to prevent the leads 50 from falling out o tube channel 23. ~ ~ :
To assemble the present pencil, firstly, coil spring 30 with lead-pushing piece 33 polnting toward the writing end of the pencil is inserted through opening~l4 into the tail portion 12 ,. :
of outer casing 10. It is lodged at front end 11 inside tube 10.

~ , , Thereafter, outer tube 10 is pressPd at an approprîate location near ~ront end 11 to form ~wo depressions 16 mentioned above, with the second windlng 34 of coil spring 30 being tightly fastened thereto. The purpose o~ fas~ening at the second winding 34 is to enable same to be coupled with irst winding 31 to acquire -increased elasticity. That is, by fastening the spring at 31, the elasticity of the front end o~ the coil sprlng 30 is increased. After coil spring 30 has been secured, the inner tube 20 is then inserted, with lead clam~ 25 being fitted through coil spring 30. Next, lead pushing member 33 of coil spring 30 i9 ~
glided or rotated into alignment with slot 27. As a result of the alignment, the front ends of the two lead clamps 25 project slightly outside of opening 13 (when the two leads clamps 25 -~ -~containing no pencil lead therein are pressed together7 their`
outside diameter will be slightly smaller than opening 13, there-ore they can project out). After inner tube 20 has been properly ~ inserted, groove 15 which extends circumferentially around outer - casing lO is pressed inwardly onto stoppers 29 on inner tube 20 so as to firmly secure inner tube 20 within outer casing 10.
Finally, the open end of capping member 40 is fitted over the tail portion of inner tube 20. An eraser 41 is then fitted into the other open end of capping member 40 which member fits within rear opening 12 of outer casing 10, thus completing the assembly of the present invention. ~ ~ ~
Fig. 8 is another embodiment oE the present invention.
It differs ~rom the above em~odiment in that four pieces o~ ~
I ~ elastic film 23b are provided on the interior sur~ace o~ internal tube 20a. ~The films 24b are located near the opening 23a of 6- ~;
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internal tube 20a. Accordingly, the opening 23c to internal tube 20a is reduced so ~.hat i~ is slightly smaller than the outside diamet~r of the pencil lead 50. Thus, it is apparent that it is not necessary to uti.lize capping member 40 although the push butto function and the preventîon of leads 50 from falling out of inner tube 20 are retained. This kind o~ construction reduces the main members of the present inventlon to three: the outer casing, the inner tube and the coil spring.
With reference to Figs. 1-5, these figures show the var-ious stages in~olved in operating the present pencil. When tube channel 21 of inner tube 20 is completely filled with presharpene ¦
lead pieces, the capacity is 12 sections. The lead p-Leces are stored in an end-to-end Xashion with the sharpened end of each pie e being pointed towards the writing end of the present pencil. Fig~
1 shows the pencil before being used. When the user starts to press or push end 23 of inner tube downwardly, protrusions 29 for coil spring 30~to be compressed, as in Fig. 2. Lead clamps 25-of inner tube 20 are fully projected outside opening 13 of outer casing 10. On the other hand, lead-pushing member 33 of coil ~
spring 30 slides along slot 27 due to the downward shift o~ lead clamps 25. When~lead-pushing members 33 reaches the end wall of ¦
slot 27, it will be forced to sl-ide onto channel 28 upon further pressing. At this time,~ the first sectlon of pencil lead 51 in inner tube 20 is no longer blocked by lead-pushing member 33 and is subsequently released. It falls automatically through the foremost end of tube channel 21. However, since front tube channe 22 is slightly smaller in diameter than lead 51, the latter is thus retained therewithin., The point of lead 51 extends through the front tube channel 22 and is exposed to thP outside as shown in Fig. 2. The user then removes his finge~ from end 23, thus ' : ~
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},rjZ3 releasing the pressure. As a result, lead clamps 25 of inner tube 20 is withdrawn into the outer casirlg 10 as coi.l spring 30 returns to almost i~s original length. I.ead-pwshing member 33 is returned to tube channel 21 after glicling through channel 28 and slot 27. Upon further retraction of inner tube 20, member 33 comes into contact with the blunt end of lead 51, thus pushing lead 51 further out of channel 21 into front tube channel 22.
When inner tube 20 is returned to ;.ts original position (that is, protrusions 29 are stopped by circular groove 15 on outer casing 10) the first lead section Sl is pushed completely into front tube channel 22 of inner 20, as shown in Fig. 3. As a result of the insertion of lead 51 into lead clamps 25, the outslde diameter of the clamps is slightly increased so that the diameter is larger than opening 13 of outer casing 10. When the user presses the pencil down onto the writing surface, an ~pward pressure is exerted, pushing the front end of inner tube into outer casing 10.
Since the outside diameter of the clamps is slightly larger than opening 13, this inward pressure forces the clamps into opening 13 so as to form an extremely tight grip on exposed lead 51.
Thus, there is no wobbling or vibrating in lead 51, which leads to a very stable writing or drawing operation. When the ~irst section of lead 51 has become blunt due to use and has to be replaced by a second section of lead 52, the above process may be repeated by pressure clown on end 23, making the two lead clamps 25 ex~end out oE outer casing 10 as shown in Fig. 4. By releasing the pressure, the lead-pushing member 33 pushes the second section of leacd 52 into channel 22, which pushes the blunt used lead 51 completely out of inner tube 20. Xowever, since lead clamps 25 _~ ; ~' :. ~ :

-- ltl~4S~3 ¦are still artially open when lead 51 is expelled, the removal of ¦
lead 51 is easily performed, withou~ any damage to the point of ¦lead 52 (see Fig. 5). The above description is detailed parti-¦cularly for the sake of ~mderstanding the working principle of ¦the present invention. It should be noted that during actual use, . ¦the pushing and releasing movements are continuous and rapid, and ¦that little exertion in handling and operation is required of the user.
¦ ~In the present invention, the pencil lead, ~tsed or not ¦used, can be withdrawn into the pencil as shown in Fig. l. The ¦user simply puts the ~ront end of an exposed pencil lead agains~
¦any surface such as a table top and press end 23 of inner tube 20 ¦lightly to have the two lead clamps 25 project slightly outside of ¦opening 13 of outer casing 10 to form an opening. In the mean-while, the rear blunt portion of the xposed lead forces away hooked tip 32 of lead-pushln~ member 33 and enters tube channel 21. Thus, as pressure is released, the entire lead section is withdrawn into the tube channels 21 and 22. Therefore, the present invention has the additional advantage of requiring no protective cap or cover for the lead. In the event that it~is not desired to have the lead retracting feature in the present ~;
invention, this can be accomplished by replacing the hooked tip 33 with a s~raight portion. However, such an embodiment would . require a protective cap to protect~the exposed lead. ~
' . The lead section used in the present invention will not be limited to pencil lead. Other working implements whlch can utili~e the construction of the present invention and~ therefore 1~ are within the scope thereof, include colored pencils, crayons, '' : ~ ,' ~: ~ , ~9~ ' ~ ~D ~ ~ ~ .

llQ~L5Z3 parafin pencils, and the like.
Furthermore, when all the penci:L leads in inner tube 20 have been used up and replacements are required, cork 61 of plastic spare tube 60 filled with a pluraLity of pencil lead is removed and the entire spare tube is inserted into opening 23 of inner tube 20. The lead pieces 56 are allowed to fall into the tube one by one to fill it completely as shown in Fig. 1. There-fore, according to this invention, the filling of new pencil leads can be done conveniently and without dirtying the fingers-of the user. However, should the user prefer, the lead may be i.nserted individually into inner t~lbe 20 without using plastic spare tube 6.
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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A writing implement comprising: an outer casing;
a coil spring having one end formed into a hooked portion and the other end being free, the spring being disposed within the outer casing; and an inner tube adapted from insertion into the outer casing and through the coil spring, the inner tube having an inside channel for storing a plurality of presharpened leads therein, the leads being stored in an end-to-end fashion with the sharpened end being pointed towards the front end of the inner tube, the front end of the inner tube being formed into conical clamp portions having two diametrically opposed slots extending from the open end and along the longitudinal axis of the inner tube, the slots having different lengths, the first slot being about 1/2 the length of a presharpened pencil lead, the second slot being five times the length of the first slot, the end wall of the second slot being excavated on the outside surface and along the longitudinal axis of the inner tube to form a slip chan-nel, the inside diameter of the inner tube being reduced at the front end by an amount sufficient to frictionally withhold the leads therein, a plurality of protrusions being disposed at about 1/3 the length of the inner tube and on the outside surface thereof for compressing the free end of the coil spring casing, the hooked portion of the coil spring being aligned to extend the hooked portion into the second slot and slide onto the slip channel when the coil spring is compressed.

2. The implement of claim 1 wherein the end of the hooked portion of the coil spring is bent outwardly towards the interior surface of the inner tube.

3. The implement of claim 2 wherein a circular groove is provided circumferentially in the outer tube to seal the coil spring within the outer and inner tubes, the groove being located about 1/3 the length from the front end of the implement.

4. The implement of claim 3 wherein a plurality of undercuts are provided near the front end of the outer tube to engage the second winding from the hooked end of the coil spring.

5. The implement of claim 3 wherein a capping member for insertion over the rear end of the inner tube is provided.

6. The implement of claim 5 wherein an eraser is inserted into the free end of the capping member.

7. The implement of claim 5 wherein a plurality of plastic films are provided on the interior surface of the capping member and near the free end thereof for sealing the pencil leads within the inside channel of the inner tube.