Note: Descriptions are shown in the official language in which they were submitted.
MECHANICAL PENCIL
TECHNICAL FIELD
This invention relates to a knocking type mechanical
pencil, and particularly to a mechanical pencil which
can accomplish lead-feeding operation by way of knocking
and in addition, can project a lead from a lead guide
merely by pushing the lead against the surface of paper
or the like, thus rendereing writing possible to perform.
~ACKGROUND
In case of performing writing by a mechanical pencil,
the length of a lead projected from the end of a lead guide
is limited to a substantially prede-termined value from a
point where the lead is liable to be broken, and when the
length of such projection is reduced due to the wear or the
like during writing, it is necessary that for example, a
button or the like provided at the rear end of a lead pipe
is knocked to thereby deliver the lead by the desired length.
However, since this lead-feeding operation is not carried
out unless writing operation is discontinued, there gives rise
to a problem in that the writing efficiency is deteriorated.
DISCLOSURE OF THE IN~ENTION
An object of the present invention is to provide
a solution of these problems noted above with respect to
prior art. An object of the invention is to provide a
mechanical pencil wherein a slider in contact with a lead
and an outer tube with different frictional resistances other
than a lead delivery mechanism for effecting lead-feed by
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general knocking operation are provided, whereby the end
of a consumed lead is pressed against or released from a
surface of paper or the like to thereby project the lead
from a lead guide by an amount corresponding to backward
movement of the slider. The lead-feeding may be easily
performed merely by pressing operation without changing the
grip of the outer tube.
In a preferred embodiment, there is provided a
mechanical pencil comprising a fore means integrally or
separately provided on an outer tube, a lead pipe axially
movably encased in said outer tube, a lead chuck connected
to said lead pipe, a check fastening ring for fastening the
end of said lead chuck, a cushion sleeve having a stopper
portion, which is in abutment with said chuck fastening
lS ring, and in engagement with either an engaging hole of
said outer tube or an engaging hole of said fore means,
a chuck fastening resilient member disposed between said
cushion sleeve and said lead pipe, and a slider member
inserted axially movably in a predetermined range with
respect to said fore means, said slider member supporting a
lead at the inner peripheral surface with a predetermined
frictional resistance and being placed in sliding contact
with the inner peripheral surface of the fore means in
the outer peripheral surface thereof with a frictional
resistance greater than the first-mentioned frictional
resistance.
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BRIEF DESCRIPTION OF T~E DRAWINGS
Fig. 1 is a sectional view o~ essential parts
showing one embodiment of a mechanical pencil having a
slider member in accordance with the present invention;
Fig. 2 is a sectional view of the whole structure
of the pencil;
Fig. 3 is a sectional view of the whole structure
o~ the pencil according to a further embodiment;
Fig. 4 is a perspective view of a slider member;
Fig. 5 is a front view of a slider member;
Fig. 6 is a side view of a slider member;
Fig. 7 is a sectional view taken on line A-A of Fig. 5;
Fig. 8 is a longitudinal sectional view of another
embodiment;
Fig. 9 is a plan view of the same;
Fig. 10 is a perspective view of a stopper portion;
Fig. 11 is a longitudinal sectional view of another
embodiment; and
Fig. 12 is a plan view of the same.
BEST MODE FOR CARR~ING OUT THE INVENTION
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Embodiments of the present invention will now
be described with reference to the drawings.
In Figs. 1 and 2, reference numeral 2 designates
an outer tube can be gripped by a hand, the outer
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tube 1 having the fore means 2 provided integrally therewith.
It is to be noted that the fore means 2 can be one separated
from the outer tube 1 as shown in Fig. 3.
A lead pipe 3 is coaxially inserted into the outer
tube 1, and a lead chuck 4 is connected to the end of
the lead pipe 3. A receiving member 5 is detachably fitted
in the rear end of the lead pipe 3 ~o accommodate an India
rubber 6 therein. The end of the lead chuck 4 extends
through the center of a chuck fastening ring 7, and ehe
rear end of the chuck fastenlng ring 7 is opposed to a
flange 8a at the front portion of a cushion sleeve 8 which
is axially movable within the outer tube 1. The cushion
sleeve 8 is formed of a resilient member such as a deformable
polyacetal or other resiliently deformable resilient members,
the cushion sleeve 8 being formed into a cylindrical
configuration as a whole, and the cushion sleeve 8 is
provided at the rear end with a stopper portion 8c which
projects outwardly from the outside diameter of a body
8b. The body 8b is provided with a cut 8d and provided
at the rear end with an axially extending C-lt 8e so that
the stopper portion 8c may generate a suitable flexible
springing force with respect to the body 8b. The stopper
portion 8c is formed into an anti-slip shape so that the
sleeve 8 may engage an engaging hole la made in the outer
tube 1 positively, smoothly and without play by one-touch
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pushing-in operation when the sleeve 8 is incorporated
into the outer tube together with a lead delivery mechanism.
Thus, the body 8b is resiliently dlsplaced with a limit
of an axial gap G portion of the cut 8d with respect to
S the stopper portion 8c supported in the engaging hole
la and the body 8b is normally urged forwardly. A chuck
fastening resilient member 9 for rearwardly urging the
lead pipe 3 is interposed between the front end of the
lead pipe 3 and the flange 8a of the cushion sleeve 8.
The fore means 2 is conically narrowed at the
end thereof, and is formed in the inner peripheral diameter
of said end with an engaging surface 10 in the form of
an inclined stepped portion for varying the inner peripheral
diameter. Encased in the inner peripheral portion of
the aforesaid end is a slider member 11 having a stopper
surface lla which is a~ially slidable but controlled in
forward displacement by the engaging surface 10.
The slider member 11 is integrally molded of a
synthetic resin such as ABS resin or polyacetal into a
tubular configuration as a whole.
This slider member 11 is integrally comprised
of two tubular members which are different in diameter
as a whole as shown in Figs. 4, 5, 6 and 7. More specifically,
reference numeral llb designates a small diam~ter portion,
and reference numeral llc designates a large diameter
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portion. A lead guide 12 is fitted under pressure or
the like into a center hole of the small diameter portion
llb to allow a lead to pass therethrough as will be described
hereinafter. Also, a through-hole lld for allowing a
lead to pass therethrough is provided in a thick-wall
portion in the vicinity of a central portion connecting
the small diameter portion llb with the large diameter
portion llc. The large diameter portion llc is in the
form of a double tube, an outer tube portion of which
is axially formed with cuts 13 at intervals equal to each
other to thereby form four sliding members 14 having a
springing force. The cuts 13 of these sliding members
14 each have in their neighbourhood a projection 15 integrally
projected. The portion near the side of each sliding
member 14 where the projection 15 is provided has a thin-
wall portion 14a so as to apply a resiliency to the sliding
member 14 more effectively. The other inner tubular portion
is provided with a cut 16 to thereby a pair of sliding contact
members 17 having a smaller springing force to lightly
hold a lead internally of the sliding member 17. While
in the illustrated embodiment, two sliding contact members 17
are provided, it is to be understood that more than two
members can be provided.
The sliding contact member 17 is formed to be reduced
in diameter gradully toward the rear end thereof or to
have substantially the same diameter as a whole, as shown
in Fig. l. Therefore, the relation of A ~ B ~ C ~ D is
established to render extrusion molding possible.
Reference numeral 19 designates a lead. Resilient
contact of the lead 19 by the sliding contact member 17
is effected by a predetermined frictional force Pl, and
the projection 15 comes into resilient contact with the
inner peripheral wall of the fore means 2 by a predetermined
frictional force P2, which is set to be suficiently great
relative to the frictional force Pl.
Next, ~he operation of the mechanical pencil will
be described.
In the state where the forward external force
is not exerted on the rear portion of the lead pipe 3,
the cushion sleeve 8 is held at the front end of a movable
region thereof, whereas the lead chuck 4 urged in the
direction of backward movement is moved back relative
to the chuck ring 7 and therefore the end of the lead
chuck 4 fastens the lead l9. In the Fig. l state, when
the lead pipe 3 is knocked from the side of the India
rubber 6, the lead chuck 4 is likewise moved forward together
with the chuck ring 7, and when the ring 7 comes into
engagement with a shoulder 2a of the fore means 2, only
the lead chuck 4 advances leaving the ring 7 to release
the fastening of the lead l9. When the aforesaid knocking
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operation is released, the lead pipe 3 is moved backward
together with the lead chuck 4, and the chuck fastening
ring 7 abuts with the front edge of the cushion sleeve
8, at which position the end of the lead chuck 4 is fastened
to hold the lead 19 and stop the backward movement of
the lead pipe 3. This operation is repeated whereby the
lead 19 is successlvely delivered. The length of the
lead 19 delivered by one lead-feed operation is approximately
equal to the distance from the front end of the ring 7
to the shoulder Za.
In the process for advancing the lead 19 by the
lead-feed operation as described above, the frictional
resistance between the lead 19 and the sliding contact
member 17 is smaller than that between the pro~ection
15 and the inner peripheral surface of the fore means
2, and therefore, the lead 19 advances from the lead guide
12 to effect writing operation in a manner similar to
a conventional mechanical pencil.
On the other hand, in the case where during writing,
the end of the lead assumes a frictional state or is broken,
the remaining lead 19 is urged against the surface of
paper or the like while gripping the outer tube 1. Therefore,
the force in the direction of backward movement acts on
the lead chuck 4 holding the lead 19 and the lead pipe
3, and these members are moved backward against the springing
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force caused by the flexure of the stopper portion 8c together
with the chuck fastening ring 7 and the cushion sleeve 8.
Tlle range of movement in the direction of backward movement
is set, for example, to 0.5 to 1.0 mm or so. Incidentally,
since the stopper portion 8c is engaged with and supported
on the cut la of the outer tube 1, the region of backward
movement of these members is the maximum dimension G.
In the process of backward movement of the lead 19, after
the end of the lead 19 has been moved backward to the
position of the end of the lead guide 12, the pressing
force also acts on the lead guide 12 from the paper surface,
and the lead guide 12 is also moved backward together
with the slider member 11. At the state where the lead
19 is moved to the rear end of the aforesaid range of
movement, the lead 19 coincides with the position of the
lead guide 12.
Subsequently~ when pressing of the outer tube
1 toward the paper surface is released, the body 8b of
the cushion sleeve 8 is moved forward to the front end
of the movable range by a righting reaction resulting
from the flexure of the stopper portion 8c whereby the
chuck fastening ring 7 moves forward together witll the
lead chuck 4 and the lead 19 held thereby and returns
to its original position. ilowever, the lead guide 12
does not move forward due to the great frictional resistance
s~
between the projection 15 and the inner peripheral wall
of the fore means 2, and thus, the end of the lead 19
is projected from the end of the lead gulde 12 by the
length corresponding to the amount of backward movement
of the lead guide 12. Similar operation may be repeated
till the lead guide 12 reaches the rear end of the movable
range thereof.
Where the lead 19 need be projected after the
lead guide 12 has reached the rear end of the movable
range thereof, the lead pipe 3 is knocked to effect normal
lead-feed operation. By this operation, the lead chuck
4 releases the fastening of the lead 19 and in the process
of further advancement, comes into contact with the rear
end of the slider member 11 to advance it to the front
end of the movable range thereof. At that time, the lead
19 is also moved forward by the same amount together with
the slider member 11, and thus, the lead 19 is maintained
so that the end thereof is in coincidence with the end
of the lead guide 12. Then, when the aforesaid knocking
operation is released, the lead chuck 4 moved backward
while leaving the lead and the lead guide 12 at that position
and stops at a position where the chuck 4 engages the
chuck fastening ring 7. If the knocking operation is
again carried out under this state, the lead 19 may be
moved forward by a predetermined length by the aforementioned
operation.
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Figs. 8 to lO show a further embodiment of the
cushion sleeve 8. In this embodiment, the cushion sleeve
8 may be mounted within the fore means 2 without an exclusive-
use jig in assembly, and when a broken lead is blocked
within the fore means 2~ the cushion sleeve 8 may be easily
removed from the fore means 2 to remove the broken lead.
The cushion sleeve 8 formed of a material similar
to that of the previously-described embodiment comprises,
as shown in Figs. 8 and 9, a body 8b whose front end comes into
abutment with the rear end of the chuck fastening ring
7 to control the movement of the ring 7 in the direction
of backward movement, a cushion portion 8f integrally
connected to the rear end of the body 8b and having an
axially expansible resilient righting property, and a coaxial
operating tubular portion 8g integrally connected to the
rear end of the cushion portion 8f.
The later-described fore means 2 is provided at
the rear end with a tapered cut guide portion 2C which
is positioned immediately behind the engaging hole 2b
as shown in Fig. 9 to guide the stopper portion 8c to
the engaing hole 2b when the cushion sleeve 8 is forced
into the fore means 2.
There are contemplated two cases in the stopper
portion 8c in engagement with the engaging hole 2b of
the fore means 2. One case is that as shown in Fig. lOa,
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a vertical wall 8Cl is formed so that the stopper portion
8c is positively secured to the engaging holes 2b so as
not to be slipped out easily, and the other case is that
as shown in Fig. lOb, the stopper portion is formed to
be tapered which gradually sharpens as the outer periphery
thereof directs upwardly so as to effect smooth engagement
with and disengagement from the engaging hole 2b.
With the above-described arrangement, asse~blage
of the cushion sleeve 8 may be carried out by holding
the operating tubular portion 8g by a hand and forcing
it into the fore means 2 from the rear end side thereof
- without use of an exclusive-use jig.
That is, when the operating tubular portion 8g
is held by the hand and forced into the fore means 2 from
the rear end side thereof, the stopper portion 8c is guided
and moved to the side of the engaging hole 2b along the
cut guide portion 2c of the fore means 2 and the stopper
portion 8c engages thereat. With this, the cushion sleeve
8 is set to the fore means 2 in a locked state (in case
of Fig. lOa) or in a disengageable fashion (in case of
Fig. lOb).
Figs. 11 and 12 also show another embodiment of
the cushion sleeve 8 which can obtain the similar effect.
The cushion sleeve 8 in this embodiment is provided with
an axial and annular operating member 8h for assembling
i2~
operation and rotating operation projected in a direction
of the outside diameter at the rear of the fore means
2 at the rear end of the operating tubular portion 8g.
Accordingly, in this embodiment, the operating
member can be held by hand more positively and simply
and the assemblage of the cushion sleeve 8 may be carried
out by pushing it into the fore means 2 from the rear
end side the~eof without an exclusive-use jig.
As described above, in the mechanical pencil accord-
ing to the present invention, a lead can be fed out by
normal knocking, and when the lead guide 12 is at a position
that may be moved backward, the end of the lead 19 is
merely pressed against ~he surface of paper or the like
without knocking operation to project the lead 19 by a
lS predetermined length. If a slider member in the form
of a single plastic molded article is used in place of
a tubular member or a frictional member such as rubber
as in prior art, the lead may be fed or projected by simple
construction and assembling operation. The sli~er member
11 may be obtained in volume and at low cost and can ~e
shortened, and therefore, the full length of the mechanical
pencil is advantageously reduced. Thus, the lead-feed
by knocking operation need not be made during the lead
19 is consumed by a portlon of movable range of the lead
guide 12 and accordingly, continuous writing can be accomplished
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without changing the gripping. Moreover, if excessive
pressure acts on the lead 19 during writing, the lead
19 is resiliently moved back by the springing action of
the stopper portion 3c, and therefore, the breakage of
the lead 19 may be effectively prevented.
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