1. Field of the Invention
The present invention relates to a lead-rotatable mechanical pencil in which the front end of a lead worn away by writing can be recovered to a pointed condition by incrementally rotating the lead during the course of writing.
2. Background Information
When the front end of a lead is worn away by writing, the line becomes thicker, and therefore there has been known a mechanical pencil having a lead-rotating mechanism in which a pointed lead condition can be recovered by rotating the lead. As the lead-rotating mechanism, various structures have been proposed. One such structure is a mechanism in which a lead is automatically rotated by utilizing writing pressure.
For example, in a mechanism described in Japanese Patent No. 4240417, a chuck unit for gripping and releasing a lead is rotatably held in a barrel, a rotation-driving mechanism drives a rotator to rotate along the retraction motion of the chuck unit by writing pressure, and the rotation motion of the rotator is transferred to the lead via the chuck unit to rotate the lead. However, in order to manufacture a mechanical pencil incorporating this mechanism, it is necessary to change the chuck unit mechanism itself from that used in conventionally known knocking-type mechanical pencils, and therefore the structures become complicated, the production is cumbersome, and such pencils cannot be obtained at low costs.
As another example, Japanese Patent No. 5193176 discloses a mechanism in which a mechanical pencil main body is rotated as a whole by which a lead can be rotated without changing or modifying the chuck unit that grips and releases the lead. This mechanical pencil is designed so that a mechanical pencil main body having a conventional, commonly used lead-feeding mechanism, such as a knocking-type mechanical pencil or a rotating-type mechanical pencil, is rotatably housed in a main body cover, and writing pressure intermittently applied during writing effects forward and backward motions of the mechanical pencil main body within the main body cover to rotate the mechanical pencil main body by which the lead is rotated. By using this mechanical pencil structure, a mechanical pencil main body having a usual lead-feeding mechanism can be used, and thus the structures become simple and can be obtained at low costs.
In Japanese Patent No. 5193176, the basic structure to rotate the mechanical pencil main body has a gear mechanism having a front gear and a rear gear provided in the main body cover, and a forward fixed gear and a rearward fixed gear provided on the outer periphery of the mechanical pencil main body. The main body cover and the mechanical pencil main body are urged by a writing pressure spring so that when no writing pressure is applied, the mechanical pencil main body advances by which the rear gear and the rearward fixed gear are meshed, and when writing pressure is applied, the pencil main body retracts by which the front gear and the forward fixed gear are meshed. The phase of the teeth of the front gear and the forward fixed gear and the phase of the teeth of the rear gear and the rearward fixed gear are shifted (out-of-phase) relative to one another. By this structure, the mechanical pencil main body rotates upon forward and backward motions. Since the rear gear and the rearward fixed gear are meshed under non-writing conditions in the mechanical pencil main body, if a person tries to forcibly rotate the part of the mechanical pencil main body that protrudes from the main body cover while gripping the main body cover, the gear mechanism parts are likely to be damaged.
The writing pressure spring that urges the mechanical pencil main body is installed between the main body cover and the forward fixed gear provided on the mechanical pencil main body. Namely, one end of the writing pressure spring abuts on the forward fixed gear provided on the pencil main body as a rotating part, and another end abuts on the main body cover as a fixed part. Accordingly, when the mechanical pencil main body rotates, the writing pressure spring rotates together with the forward fixed gear, frictional resistance is produced between one end of the writing pressure spring and the main body cover, whereby the mechanical pencil main body is not smoothly rotated and the lead may fail to securely rotate.
An object of the present invention is to provide a mechanical pencil having a lead-rotating mechanism that overcomes the aforementioned drawbacks of the prior art.
Another object of the present invention is to provide a mechanical pencil having a lead-rotating mechanism that incrementally rotates a lead utilizing writing pressure intermittently applied during writing.
A further object of the present invention is to provide a mechanical pencil having a mechanical pencil main body housed in a main body cover to undergo rotational movement and axial forward-and-rearward movement in the main body cover, and having a gear mechanism that incrementally rotates a lead in response to forward and rearward movement of the mechanical pencil main body caused by writing pressure intermittently applied during writing.
A further object of the present invention is to provide a mechanical pencil having a mechanical pencil main body slidably and rotatably housed in a main body cover to undergo forward-and-backward movement and rotational movement to securely incrementally rotate a lead when the mechanical pencil main body moves forward and rearward.
Another object of the present invention is to provide a mechanical pencil in which a mechanical pencil main body is rotated in a main body cover by writing pressure to rotate a lead and in which a gear mechanism that rotates the mechanical pencil main body will not be damaged by forcibly rotating the mechanical pencil main body when the mechanical pencil is not in use.
The foregoing and other objects of the present invention are realized by a mechanical pencil having a tubular main body cover and a mechanical pencil main body slidably and rotatably housed in the main body cover to undergo forward-and-backward movement and rotational movement to feed a lead from the front end of a barrel. On the inner face of the main body cover, a front gear having teeth facing forward and a rear gear having teeth facing backward are formed. On an outer periphery of the mechanical pencil main body, a forward fixed gear having teeth that mesh with the front gear and a rearward fixed gear having teeth that mesh with the rear gear are provided. A writing pressure spring urges the mechanical pencil main body so that when writing pressure is applied, it allows the mechanical pencil main body to axially retract and when the writing pressure is eliminated, the mechanical pencil main body is moved axially forward to mesh the rear gear and the rearward fixed gear. The phase of the teeth of the front gear and the forward fixed gear and the phase of the teeth of the rear gear and the rearward fixed gear are shifted (out-of-phase) so that the mechanical pencil main body incrementally rotates when the mechanical pencil main body moves forward and backward. On the outer periphery of the mechanical pencil main body that is exposed from the main body cover, rotatable protection collars are provided so that the mechanical pencil main body cannot be rotated by application of an external force.
The protection collars preferably comprise a tapered collar provided at the front end side of the mechanical pencil main body and a main body collar provided at the rear end side of the mechanical pencil main body. The writing pressure spring is disposed between the main body cover and the forward fixed gear. One end of the writing pressure spring is supported by the main body cover or the forward fixed gear via a rotatable slide ring. Further, the main body cover is preferably provided with a window through which the rotation condition of the mechanical pencil main body can be seen from the outside.
In the mechanical pencil of the present invention constructed as above, when the writing pressure is applied during use, the mechanical pencil main body axially retracts in the main body cover, and when the writing is stopped, the writing pressure is no longer applied and the mechanical pencil main body axially advances. During the forward and rearward motions, the mechanical pencil main body incrementally rotates by which the lead is rotated. Further, even if a person tries to grip the mechanical pencil main body exposed from the main body cover and rotate it, since the exposed portion is covered with a rotatable protection collar, the protection cover idles and therefore the mechanical pencil main body is not rotated. Accordingly, it is possible to avoid damage to the rear gear and the rearward fixed gear which are in meshing engagement during nonuse of the mechanical pencil.
Also, when one end of the writing pressure spring is supported by the main body cover or the forward fixed gear via a rotatable slide ring, the frictional resistance generated at the end portion of the writing pressure spring can be reduced due to rotation of the slide ring, whereby the mechanical pencil main body rotates smoothly and the lead can be rotated securely.
Additional objects, advantages and features of the present invention are set forth in the following description and others will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention.
The mechanical pencil main body 2 as shown in this example has basically the same structure as that of well-known knocking-type mechanical pencils. Briefly explaining, the main body 2 comprises a barrel 3 into which is inserted a lead reservoir 5 accommodating one or more leads 4. To the front end of the lead reservoir 5, a chuck 6 for releasably gripping the lead 4 is connected. A chuck ring 7 is fitted on the outer periphery of the chuck 6 to control the opening and closing of the chuck, and the lead reservoir 5 is urged rearwardly by a compression spring 8. At the rear end of the lead reservoir 5 are attached an eraser 9 and an eraser cover 10. At the front end of the barrel 3, a tapered member 11 is threadedly attached. In the tapered member 11, an internal stepped portion 12 is formed and on which the chuck ring 7 abuts when the lead reservoir 5 is knocked, and a slider 14 having a lead-protecting pipe 13 is slidably disposed to undergo forward and backward movement. On the slider 14, a lead-holding portion 15 is provided to temporarily hold the lead 4 fed by a knocking operation.
Referring to
On the inner face of the tapered member 11, as shown in
The main body cover 1 has, as shown in
According to this embodiment of the present invention, inside the main body cover 1, a crosswise partition 34 is formed, and the partition has a through-hole 33 through which the barrel 3 of the mechanical pencil main body 2 is inserted as shown in
Fitted on the outer periphery of the barrel 3 of the main body 2 are a forward fixed gear 38 having teeth 38a configured to mesh with the front gear 35 of the main body cover 1 (
The forward fixed gear 38 is formed in a tubular shape, and as shown in
The rearward fixed gear 39 is, as shown in
The forward fixed gear 38 and the rearward fixed gear 39 may be integrally formed with the barrel 3. If the forward fixed gear 38 and the rearward fixed gear 39 are constituted by different parts from the barrel 3, the fixed gears 38, 39 may be made of a plastic material having a strength higher than that of the barrel 3, by which it becomes possible to obtain a durable mechanical pencil. As mentioned above, the shapes of respective teeth of the forward fixed gear 38 and the rearward fixed gear 39 are formed in a substantially herringbone shape so that they will mesh with the front gear 35 and the rear gear 36, respectively. Further, the phases of the teeth 35a are shifted with respect to the teeth 36a so that the pencil main body 2 can be incrementally rotated by meshing the forward fixed gear 38 and the rearward fixed gear 39 with the front gear 38 and the rear gear 39, alternately, by forward and backward motions of the main body 2.
The writing pressure spring 42 inserted into the rear end portion of the forward fixed gear 38 is incorporated so that it may rotate with the forward fixed gear in this embodiment. The rear end of the writing pressure spring 42 abuts on a slide ring 50, and the slide ring 50 is held by the receiver 37 provided at the partition 34 of the main body cover 1. The slide ring 50 is, as shown in
The writing pressure spring may also be incorporated in a way that it does not rotate together with the forward fixed gear. In this instance, a slide ring is provided between the internal stepped part of the forward fixed gear and the front end of the writing pressure spring, and the rear end of the writing pressure spring is allowed to abut on the partition of the main body cover, whereby when the forward fixed gear is rotated, slippage occurs between the forward fixed gear and the slide ring.
In the embodiment shown in
As shown in
In the main body collar 57, as shown in
In order to incorporate the main body 2 into the main body cover 1, the rearward fixed gear 39 is attached to the barrel 3 and then the mechanical pencil main body 2 is inserted from the rear portion of the main body cover 1. Through the through-hole 33 of the partition 34 of the main body cover 1, the main body 2 is inserted, and the forward fixed gear 38 having the writing pressure spring 42 and slide ring 50 incorporated is attached to the front part of the barrel 3 from the front portion of the main body cover 1. The tapered member 11 is threadedly attached to the barrel 3 to prevent detachment of the forward fixed gear 38. Then the tapered collar 56 is attached to the outer periphery of the tapered member 11 and the main body collar 57 is attached to the rear end of the barrel 3.
By the above structure, when no writing pressure is applied, since the main body 2 is urged forward by the writing pressure spring 42 as shown in
More particularly, during rearward movement or retraction of the main body 2 from the position illustrated in
In the engagement and disengagement of the gears, since the phase of the teeth of the forward fixed gear 38 and the front gear 35 is displaced relative to the phase of the teeth of the rearward fixed gear 39 and the rear gear 36, the main body 2 having the forward fixed gear 38 and the rearward fixed gear 39 rotates incrementally, and as a result, the lead 4 rotates. When the main body 2 rotates, since the main body cover 1 does not rotate, the slidable contact projections 54 of the slide ring 50 supporting one end of the writing pressure spring 42 slide on the surface of the receiver 37 of the main body cover 1. Since the frictional resistance generated at this time is smaller than the case where the writing pressure spring 42 is directly supported by the receiver 37 of the main body cover 1, the main body 2 smoothly rotates together with the forward and rearward motions of the main body 2, and the lead 4 is securely rotated. Rotation of the main body 2 can be seen via the window 32 provided beneath the clip as shown in
As mentioned above, in the mechanical pencil according to the present invention, the outer face of the mechanical pencil main body 2 exposed from the main body cover 1 is covered with one or more rotatable protection collars 55 and in this embodiment, the exposed portions of the main body 2 at the front and rear portions of the main body cover 1 are covered with the tapered collar 56 and the main body collar 57. Accordingly, even if a person tries to rotate the mechanical pencil main body 2 by gripping the protection collars, these collars idle and the mechanical pencil main body does not rotate, and therefore it becomes possible to avoid damage to the gear mechanism. The main body cover 1 and the barrel 3 of the mechanical pencil main body 2 can be constructed in an appropriate length, size, shape, etc., so that the part or parts of the mechanical pencil main body 2 exposed from the main body cover 1 can be changed as desired. In such instance, depending on the location of the exposed part or parts, the number and shape of the protection collars can be appropriately selected.
For example, as shown in the embodiment of
In another example shown in the embodiment of
It will be appreciated by those skilled in the art that obvious changes can be made to the examples and embodiments described in the foregoing description without departing from the broad inventive concept thereof. It is understood, therefore, that this disclosure is not limited to the particular examples and embodiments disclosed, but is intended to cover all obvious modifications thereof which are within the scope and the spirit of the disclosure as defined by the appended claims.
Number | Date | Country | Kind |
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2013-154154 | Jul 2013 | JP | national |