Mechanical pencil

Abstract

There is provided a push type mechanical pencil with which a user can push out a lead with a fingertip work while keeping a writing posture and a grasping position unchanged. In this mechanical pencil, a hole is formed at the part of the outer cylinder at which a user's finger tip will be positioned when the pencil is grasped in writing position, and there are also provided a push member slidably fitted in said hole with the lower end thereof extending into the inside of said outer cylinder, and an engaging member secured to the inner cylinder in contact with or in close proximity to the lower end of said push member whereby when the user pushes said push member downwardly toward the inner cylinder, the lower end of said push member pushes the engaging member to move forwardly against the spring force to thereby force out the lead.

Description

This invention relates to a novel push type mechanical pencil provided with chuck means.

In conventional push type mechanical pencils having chuck means, knock cap is provided at the rear part of an inner cylinder disposed within an outer cylinder, and when in use, said push button is knocked or pushed against the spring force to release hold on the chuck means to thereby allow the lead to extend out through a certain given length. Therefore, when the lead is worn out or broken in use, the user must change his grip on the outer cylinder or holder and then push the rear cap. This is very troublesome particularly when a dark or thick-colored lead is used which wears off rapidly.

It is therefore an object of the present invention to provide a novel push type mechanical pencil in which the lead can be propelled with a simple finger-tip work of one of the user's fingers grasping the pencil holder while maintaining a writing posture.

It is another object of the present invention to provide an mechanical pencil of the type, in which the propelling of the lead can be effected with a relatively small pressing force.

Still another object of the present invention is to provide an mechanical pencil of the type, in which a lead push-out mechanism is incorporated conveniently at the part of the outer cylinder or holder of the pencil at which a user's finger-tip is positioned during a writing practice.

A further object of the present invention is to provide an mechanical pencil of the type mentioned above, which is easy to be assembled, simple in construction and can be manufactured at a low cost.

In order to accomplish these objects, there is provided according to the present invention a novel and improved push type mechanical pencil comprising an outer cylinder; an inner cylinder having at its fore end a lead gripping chuck and also formed with a passage communicated with said chuck means and a spare leads containing tube communicated with said passage; and a spring means adapted to constantly press the inner cylinder rearwardly in the axial direction, wherein said push type mechanical pencil further comprises a hole at the part of the outer cylinder at which a user's finger tip will be positioned when the user grasps the pencil for a writing practice, and there are provided a push member disposed covering and projecting out from the hole, with the lower end of the member extending into the inside of said outer cylinder, and an engaging member secured to said inner cylinder in contact with or in close proximity to the lower end of said push member, whereby when the user pushes said push member downwardly toward the inner cylinder, the lower end of said push member depresses said engaging member to move forwardly against the resisting force of the spring means, thereby forcing the lead to pop out from the end of the pencil.

The engaging member may be tapered at its rear portion such that the tapered portion will be depressed by the lower end of the push member as the latter is pushed down, thereby the engaging member as well as the inner cylinder joined thereto are moved forwardly. Also, the push member may be made of a bent lever having an inner engaging portion and an outer push portion, both of which are arranged with a certain angle formed relative to each other. The lever is pivotted at its bend to the outer cylinder such that when the outer push portion of the lever is depressed, the inner engaging portion of said lever will be turned about its pivot to push and move the engaging member forwardly. The push member may be made of a T-shaped block having a stem portion extending through the hole and an enlarged head portion, and may be arranged in such a manner that the bottom end of said stem portion rests on the engaging member and is normally pressed upwardly by the spring. The engaging member is pushed forwardly when the T-shaped member is depressed.

The aforementioned and other objects and features of the present invention will be apparent from the following detailed description of a specific embodiment thereof, when read in conjuction with the accompanying drawings, in which:

FIGS. 1 to 4 show the essential parts of a push type mechanical pencil having a T-shaped push member according to the present invention. In the figures, FIGS. 1, 2 and 4 show sectional side views of the essential parts in the respective embodiments and FIG. 3 shows an annular leaf spring used in an embodiment shown in FIG. 2;

FIGS. 5 to 9 show embodiments of the push type mechanical pencil according to the present invention where a lever-like push member is employed. In the figures, FIG. 5 shows a sectional side view of the essential parts and FIGS. 6 to 9 show exploded views of the essential parts of the pencil;

FIGS. 10 to 17 show further embodiments of the present invention where an elastic plate is used as a push member. In the figures, FIGS. 10, 12, 14 and 17 show sectional views of the essential parts of the pencil in the respective embodiments, while FIGS. 11, 13 and 16 show in perspective the elastic plates used in the embodiments shown in FIGS. 10, 12 and 14, respectively, and FIG. 15 shows an outer cylinder used in the embodiment shown in FIG. 14.

Relating first to the embodiments using a T-shaped push member as shown in FIGS. 1 to 4, an outer cylinder 1 has at its fore end a ferrule 2 which is threadedly secured to the fore end through an annular threaded member 3, and an opening at the rear end of said outer cylinder is closed with a plug 4. A small guide pipe 5 for a lead 6 is provided extending through the fore end portion of the ferrule 2. In the inside of the outer cylinder 1 is disposed an inner cylinder 10 having at its fore end a chuck means 11 and also forming a lead passage 12 communicated with the chuck means 11 and a tube 13 containing spare leads. The tube 13 is communicated with the lead passage 12. In these embodiments, the lead passage 12 of the inner cylinder 10 is formed from a lead guide pipe 14 integral with the chuck means and an engaging member 20, the rear end of which is fitted in the spare leads containing tube 13 and the fore end is threadedly secured to the tube 13. Chuck means 11 is arranged to be engaged with a ring 15 in said annular threaded member 3 in a known way. A spring 16 is compressedly interposed between the front end of said engaging member 20 and the inner wall at the fore part of the outer cylinder 1, so as to press the inner cylinder 10 rearwardly along its axis.

It is to be also noted that a hole 30 is formed at the part of the outer cylinder 1 at which a user's finger tip will be positioned when he grasps the outer cylinder in writing position. In this hole 30 is fitted a T-shaped push member 40 which is formed from a stem portion 41 extending through the hole and an enlarged head portion 42. Disposed below the T-shaped push member 40 is the engaging member 20 whose outer periphery is taperly bulged out in V shape (in section) to form two-way bevels 21. The lower end of the stem portion 41 of the T-shaped push member 40 is also tapered to form a bevel 43 which corresponds to and abuts against the right-hand side (in FIG. 1) of the two-way bevels 21 of the engaging member 20. A stopper 14 having a greater diameter than the hole 30 is secured to a lower part of the stem portion 41 of the push member 40.

Normally, the inner cylinder 10, which is pressed rearwardly by the spring 16, abuts against the engaging member 20 so that the push member 40 is normally urged upwardly with its bevel 43 being contacted with the corresponding bevel 21 of the engaging member 20, as shown in FIG. 1. When the user pushes the head portion 42 of the T-shaped push member 40 with one of his fingers grasping the outer cylinder 1 in a writing posture, both of the bevels 21 and 43 slide against each other, causing the engaging member 20 to move forwardly against the force of the spring 16 whereby the lead 6 is pushed out by the action of the chuck means 11 in a known way. If the finger positioned on the head portion 42 of the push member 40 is removed, the push member 40 is forced back upwards by sliding movement of the both bevels 21 and 43 relative to each other, but is stopped to stay at the position of FIG. 1 by means of the stopper 44. It is possible to let the lead extend out to a desired length by repeating the above-described operation.

In the embodiment shown in FIGS. 2 and 3, an annular leaf spring 23 is secured around an annular plug 22 mounted at the front of the spare leads container tube 13, with one end of the leaf spring 23 being anchored to the stem portion 41 of the push member 40 and the other end anchored to the outer cylinder 1. As shown in FIG. 2 the leaf spring 23 is so constructed that its annular portion will be bent or flexed forwardly when pressed at its one end and will restore its original condition when the pressure is released. This allows push-out of the lead 6 in a way similar to the embodiment shown in FIG. 1 by operating the push member 40.

In the embodiment shown in FIG. 4, a pin 24 extends parallel to the hole 30 from the annular plug 22 mounted at the front of the spare leads containing tube 13. The pin 24 is arranged to engage in an elongated slot 46 formed in an enlarged bottom part 45 of the stem portion 41' of the T-shaped push member 40'. The elongated slot 46 extends forwardly, obliquely and toward the hole 30 from a lower point of the enlarged bottom element 45 as shown in FIG. 4. The pin 24 normally stays at the bottom-most end of the slot 46, but when the head portion 42' of the push member 40' is depressed, the pin 24 is urged to advance forwardly along the slot 46, thereby effecting a lead push-out action in a similar way to the preceding embodiments.

Discussion is now turned to another form of the push type ever-sharp pencil according to the present invention where there is employed a lever-like push member. In this form of the device, the lead passage 12 of the inner cylinder 10, which is communicated with the chuck means 11 at the fore end and with the spare leads containing tube 13 at the rear end, is constituted from a lead guide pipe 14 formed integral with the chuck means 11 and an engaging member (25). The engaging member (25) is threadedly engaged with the lead guide pipe 14 and the spare leads containing tube 13 at the fore and rear ends thereof respectively, and the engaging member 25 is forming at the fore end thereof an enlarged annular portion 26 to which one end of the spring 16 abuts.

A hole 30 is formed at the portion near to the finger-tip portion of the outer cylinder 1. In case of constituting the outer cylinder 1 from two members as shown in FIGS. 5 to 7, the hole 30 may be formed by suitably spacing apart the both members, while in case of constituting the outer cylinder from a single member as shown in FIGS. 8 and 9, such a hole may be formed by perforating said member.

Passed through said hole 30 is a bent lever 50 having an inner engaging portion 51 and an outer push portion 52 which are arranged forming certain angles 90.degree. to 180.degree. relative to each other, and the lever 50 is swingably pivotted at its angled portion to the outer cylinder 1. Preferably, the inner engaging portion 51 is formed bifurcated and is pivotally secured to the outer cylinder 1 in such a manner that the fork strides over the tubular engaging member 25 and is positioned behind and normally in close proximity to the enlarged annular portion 26.

There are various ways for pivotally attaching the lever 50 to the outer cylinder 1 in a manner preferred for easy assemblage. In the embodiment shown in FIG. 5, a detent 53 is formed integral with the lever 50 at an upper part of its inner engaging portion 51 such that the detent will be positioned inside of and in close proximity to the outer cylinder 1 when the two members of said outer cylinder are threadedly joined together. In the embodiment of FIG. 6, shoulders 54 are formed at the top of the inner engaging portion 51 of the lever 50 such that the shoulders will be positioned in the inside of and in close adjacency to the edges of an elongated hole 30, which is shown in FIG. 4, formed longitudinally in the outer cylinder 1. In these arrangements of the lever 50, the outer push portion 52 is projected outside of the outer cylinder 1 as shown.

In an embodiment shown in FIG. 7, a pin 55 is provided such that it fits at its both ends in the horizontal grooves 56 formed in opposed relation in the inner wall of the outer cylinder 1 and is also engageable in the slant grooves 57 formed at the angled portion of the lever 50.

In still another embodiment shown in FIG. 8, a bridge-like portion 33 bridging a hole 32, which corresponds to the elongated hole 30 of the aforementioned embodiments shown in, for example, FIGS. 1 and 4 in the outer cylinder 1 substantially at its middle portion to divide the hole 32 into two parts is provided integral with the outer cylinder 1 such that the bridge-like portion 33 will engage in a convolute groove 58 formed in the angled portion of the lever 50. If necessary, the fore portion 32a of the hole 32 may be filled up with a cover member 34.

In another embodiment of FIG. 9, a bearing plate 36 is attached to the inner wall of the outer cylinder 1 having a hole 35, and a pin 59 adapted at the angled portion of the lever 50 so as to swingably support the lever is received in and supported by slots 37 formed in the bearing plate 36. Although not shown, a plate adapted to swingably support the lever 50 may be provided in the outer cylinder 1 instead of using the pin 59 in the embodiment shown in FIG. 9.

In the embodiments shown in FIGS. 7 to 9, the lever 50 is mounted swingable about the pin 55 or 59 or the bridge-like portion 33, and hence the outer push portion 52 of the lever 50 can be normally positioned substantially flush with the external surface of the outer cylinder 1 so that it will not spoil the external appearance of the pencil. Preferably, arrangement is made such that when the chuck means 11 is not gripping the lead 6, the enlarged annular portion 26 of the engaging member 25 may stay in direct abutment against the inner engaging portion 51 of the lever 50. Even if such arrangement is used, when the chucking means 11 once grips the lead 6, the chucking means is expanded out by an amount of thickness of the lead 6, thus partly preventing return to the chuck guide ring 15, and as a consequence, there is formed a slight gap between the enlarged annular portion 26 of the engaging member 25 and the inner engaging portion 51 of the lever 50 as shown in FIG. 5. Therefore, in order to prevent rattling of the lever 50, it is desirable to dispose a weak spring 100 between the lever 50 and the inner wall of the outer cylinder 1 with the bridge 33 or the pin 55 59 as a fulcrum, or a supporting position as shown in FIGS. 7 and 8.

The mechanical pencil having a lever-like push member 50 according to the present invention is constructed as substantially same as described above, so that when the user pushes the outer push portion 52 of the lever 50 with one of his fingers grasping the outer cylinder 1 in a writing posture, the inner pressing portion 51 is turned about the bearing of its angled portion, with the end of the pressing portion 51 pushing the enlarged annular portion 26 of the engaging member 25 forwardly, thereby urging the lead to pop out from the foremost end of the pencil with the aid of the chucking means 11. When the pressing force on the outer portion 52 of the lever 50 is released, the engaging member is forced to move back by the action of the spring 16 and its enlarged annular portion 26 pushes back the inner pressing portion 51 of the lever 50, causing the lever 50 to turn about its bearing section to return to its normal position. It is thus possible to push the lead 6 out to a desired length by repeating the above-described operation.

In the embodiments employing such a lead push-out lever 50, it is possible to perform the lead push-out operation with a relatively small pressing force by providing a greater distance between the pivot of the lever 50 and the end of the outer push portion than the distance between the pivot and the end of the inner pressing portion.

Discussion is now focussed on still other embodiments employing an elastic plate 60 for a pressing member as shown in FIGS. 10 to 17.

A ferrule 2 is secured to the end of the outer cylinder 1 by means of an annular threaded member 3, and an inner cylinder 10 comprising a chuck means 11, a lead guide passage 12 and a spare leads containing tube 13 is disposed within said outer cylinder 1. The lead guide passage 12 is formed from a lead guide pipe 14 communicated with the chuck means 11 and the tube 13 connecting the lead guide pipe 14 to the spare leads containing the tube 13. An enlarged annular portion 18 is formed at the rear end of the lead guide pipe 14, and a spring 16 is compressed between the annular threaded member 3 and the enlarged annular portion 18. Also, a tapered engaging member 27 is fitted in the tube 13 behind and in abutment against the enlarged annular portion 18.

An elongated slot 38 is formed longitudinally at a fore part of the outer cylinder 1 where a user's fingertip will be positioned when he grasps the outer cylinder for a writing practice. Inside the fore edge of the slot 38 is located the rearwardly inclined bevel 28 of the tapered engaging member 27. There is also provided an elastic plate 60 which is disposed covering the elongated slot 38 and engaged at its one end with the outer cylinder 1. This elastic plate 60 has side walls 61 suspending from both sides of the other end of the plate, with the fore edges 62 of the side walls always abutting against an upper part of the bevel of the engaging member 27.

In operation, when the user pushes a top part of the elastic plate 60 above the side walls 61 with one of his fingertips gripping the outer cylinder 1, the plate 60 is forced to bend about its point engaged with the outer cylinder 1 and the fore edges 62 of its side walls push the bevel 28 of the engaging member 27 to let it move forwardly, thereby effecting push-out of the lead. When the pressing force of the user's fingertip on the elastic plate 60 is released, the engaging member 27 is forced back to its original position by the spring 16, with the elastic plate 60 being also pushed back by the bevel 28 of said engaging member to the position substantially flush with the external surface of the outer cylinder 1. Preferably, pawls 63 are formed projecting horizontally from the bottom ends of the side walls of the elastic plate 60 so that they will engage in the corresponding grooves formed in the inner wall of the outer cylinder 1, thereby to inhibit the elastic plate 60 from bending and projecting further upwardly when it is pushed back to its normal position.

There are various ways for mounting the elastic plate 60 in position in the outer cylinder 1. In embodiments shown in FIGS. 10 and 11, the rear end of the elastic plate 60 is bent in U shape and snugly housed in a small hole in the outer cylinder 1 located behind the elongated slot 38. Also, pawls 63 project horizontally from the bottom ends of the side walls 61 so as to engage in the corresponding grooves in the inner wall of the outer cylinder 1. According to this arrangement where the rear end 64 of the elastic plate 60 is bent in U shape and forcedly fitted in a small hole in the outer cylinder 1, the elastic plate 60 is urged upwardly rather strongly, so that it is possible to normally keep the plate face in alignment with the external surface of the outer cylinder with ease.

In the embodiment shown in FIGS. 12 and 13, the rear end of the elastic plate 60 is held up by a stopper means 65 formed in the inside of the outer cylinder 1 behind the elongated slot 38, and only the upper face of the fore pressing portion covers the slot 38. In this case, too, pawls 63 are provided protruding horizontally from the bottom ends of the side walls of the elastic plate 60 so as to engage in the corresponding grooves in the inner wall of the outer cylinder 1 to thereby prevent the elastic plate 60 from being projected upwardly from the position of FIG. 12. In this embodiment, since the elongated slot 38 is closed with the push portion of the elastic plate 60, the user may push any part of the elastic plate 60 covering said slot to effect a smooth lead push-out operation.

In still another embodiment shown in FIGS. 14 to 16, the elongated slot 38 is divided into a fore larger hole 38a and a rear smaller hole 38b by a bridge 39 formed integral with the outer cylinder 1, and the rear end of the elastic plate 60 is bent in L shape and tailed in the rear smaller hole 38b. Pawls 63 are also provided projecting horizontally from the bottom ends of the side walls of the elastic plate 60. In this embodiment, the tapered engaging member 27 is directly pressed rearwardly by the spring 16, but it is of course possible to adopt the arrangement used in the embodiments shown in FIGS. 10 to 14. In this embodiment, the elastic plate 60 is bent about the bridge 39, so that when in the bent position, the spring portion located behind the bridge 39 exerts a strong reaction against the inner face of the outer cylinder 1. Therefore, if the pressing force on the elastic plate is released, the respective elements are quickly returned to their original positions and, also, the spring force does not run down even if used for a long time.

In the embodiment of FIG. 17, which is quite contrary to the embodiment of FIG. 16, the elongated slot 38 is divided by a bridge 39 into a fore smaller hole 38c and a rear larger hole 38d, and the fore end of the elastic plate 60 is bent in L shape and tailed in the fore smaller hole 38c. The elastic plate 60 has side walls suspending from both sides of its rear end and arranged in such a manner that the fore edges of said side walls will push the opposed bevel of the engaging member 27.

In the embodiments shown in FIGS. 10 to 17, since the pressing member is made of an elastic plate 60, mounting thereof in position in the outer cylinder 1 is very easy. That is, an end of the plate is firstly secured to an end of the elongated slot 38 formed in the outer cylinder 1, then both side walls 61 are pushed to bend them inwardly and forcedly inserted into the elongated slot 38, and then the pawls 63 are engaged in the corresponding grooves in the inner wall of the outer cylinder. This arrangement is therefore expedient for assemblage of the parts.

While the present invention has been described by way of some preferred embodiments thereof, it will be understood that various modifications and alternations can be made within the sprit of the present invention.

Claims

I claim:

1. In a push type mechanical pencil comprising an outer casing; an inner casing having at its fore end a lead gripping chuck means and also formed with a lead passage communicated with said chuck means and a spare leads housing tube communicated with said lead passage; and a spring means adapted to press said inner casing rearwardly along its axis, wherein said push type mechanical pencil further comprises a fore larger hole and a rear smaller hole both formed in alignment through said outer casing and defined by a bridge formed integral with said outer casing, said fore larger hole being formed at a place where a user's fingertip is positioned when the user grasps said outer casing, an elastic push plate adapted to normally lie covering said holes along the external surface of said outer casing, said push plate being bent in L-shape at its rear end portion and tailed in said rear smaller hole such that said push plate is bendable about said bridge, said push plate having side walls suspending from both sides of its fore end portion and extending into the inside of said outer casing, and an engaging member secured to said inner casing at the rear part of said spring and having a tapered surface formed at the rear portion thereof on which the fore edges of said side walls of said push member acts, whereby when the user pushes said push plate downwardly toward the inner casing, the fore edges of said push plate push said engaging member to move forwardly against the resisting force of said spring, thereby pushing out the lead into a writing position.

2. A push type mechanical pencil as claimed in claim 1 wherein said push plate has pawls projecting horizontally from the bottom ends of said side walls thereof, said pawls being engageable with shoulders formed inside of said outer casing.

3. In a push type mechanical pencil comprising an outer casing; an inner casing having at its fore end a lead gripping chuck means and also formed with a lead passage communicated with said lead passage; and a spring means adapted to press said inner casing rearwardly along its axis, wherein said push type mechanical pencil further comprises an elongated slot formed at a part of said outer casing at which a user's fingertip is positioned when the user grasps said outer casing in writing position, a push member formed of an elastic plate adapted to normally lie covering said slot along the external surface of said outer casing, said push member having side walls suspending from both sides of its fore end portion and extending into the inside of said outer casing, and an engaging member secured to said inner casing at the rear part of said spring and having a tapered surface formed at the rear portion thereof on which the fore edges of said side walls of said push member acts, whereby when the user pushes said push member downwardly toward the inner casing, the fore edges of said push member push the engaging member to move forwardly against the resisting force of said spring, thereby pushing out the lead into a writing position, wherein the rear end of said push member is held up by a stopper means provided in the inside of the outer casing.