Coating implements with material supply – Solid material for rubbing contact or support therefor – Including holder
Reexamination Certificate
2000-02-02
2001-03-20
Walczak, David J. (Department: 3751)
Coating implements with material supply
Solid material for rubbing contact or support therefor
Including holder
C401S067000, C401S065000
Reexamination Certificate
active
06203227
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a double chuck type mechanical pencil provided with a rear chuck for drawing out a lead in a fixed amount having a chuck ring loosely fitted thereon, and a front chuck for preventing a lead from retreating.
2. Description of the Prior Art
Conventionally, various double chuck type mechanical pencils have been proposed for mainly reducing a loss of a lead. However, in the double chuck type mechanical pencil of this kind, where a lead is held by two chucks, when one chuck is rotated for some reason, the held lead is twisted and becomes broken. In such a case as described, chips of the broken lead remain in and between the front chuck and the rear chuck to disturb the drawing-out of a lead, and when a posterior lead is pushed out after the preceding lead was broken, the broken chips of the preceding lead are deviated from the posterior lead, thereby making it impossible to draw out the posterior lead.
For overcoming such an inconvenience as described above, a double chuck type mechanical pencil has been proposed in which a rear chuck cannot be rotated, as disclosed in Japanese Patent Laid-open No. Hei 7-228087, for example.
Referring now to
FIG. 1
, there is illustrated the double chuck type mechanical pencil disclosed in the above publication. The double chuck type mechanical pencil comprises a tip member
22
provided in the front portion of an axial tube
21
, an end chuck
25
incorporated in the tip member
22
and biased rearward in a longitudinal direction by means of a front spring
23
to hold a lead
24
, and a draw-out chuck
26
positioned rearward in a longitudinal direction from the end chuck
25
to draw out the lead
24
, wherein a connector
28
connected to the draw-out chuck
26
can be slidably moved in a longitudinal direction but cannot be rotated with respect to an inner sleeve
27
connected to the tip member
22
.
More particularly, axially extending key ways
27
a
are formed in the inner sleeve
27
, keys
28
a
of the connector
28
are engaged with the key ways
27
a
to make the draw-out chuck
26
unrotatable, and the lead
24
held between the end chuck
25
and the draw-out chuck
26
is prevented from being twisted and snapped off.
In the conventional mechanical pencil as described above, however, particularly where the tip member is formed of synthetic resin, the end chuck collides with the extreme end of the tip member during use to wear that portion, resulting in inaccuracy of fitting relative to the end chuck and raising the possibility that the mechanical pencil becomes inoperative.
Further, where the tip member is prepared with a metal having abrasion resistance, the construction of the tip member becomes complicated so that it takes time to finish an opening diameter of the tip member with accuracy by plating, etc., in terms of the outside diameter of the end chuck. Further, since a large tip member is bored to form an opening, a burr tends to occur in the opening. Accordingly, there occurs an inconvenience that accuracy of the opening diameter is low and it takes time to remove the burr so that cost increases.
Furthermore, according to the prior art, for eliminating snapping-off of a lead held between both the chucks caused by twisting thereof, detent of the rear chuck and locking or adhesion between the tip member and the axial tube are necessary, which parts are complicated in construction, posing an inconvenience that it takes time to manufacture and assemble parts, increasing the cost.
SUMMARY OF THE INVENTION
In view of the foregoing, this invention overcomes the disadvantages as noted above with respect to prior art. An object of the invention is to prevent abrasion around an opening at the extreme end of a tip member caused by impingement of a front chuck. Another object of the invention is to simplify the manufacture of the tip member so as to enhance accuracy and to be suitable for manufacture in quantity. A further object of the invention is to eliminate the complicated construction for detent of a rear chuck and provide a construction in which a front chuck is rotated together so as to eliminate snapping-off of a lead held caused by twisting as the chucks rotate. Further, since a loosely fitted tube rotates at an opening portion of the tip member, turning force will not extend to the front chuck when the tip member is removed even if locking or adhesion between the tip member and the axial tube is not provided, thus not giving rise to twisting of a lead caused by rotation of the chucks.
For achieving the aforesaid object, according to this invention, there is provided a double chuck type mechanical pencil comprising: a lead tank slidably provided within an axial tube; a rear chuck for drawing out a lead fixedly mounted on the front end of the lead tank; a chuck ring loosely fitted in the rear chuck; a rear resilient component for biasing rearward the lead tank and the rear chuck; and a front chuck for holding a lead connected to the rear chuck through a connecting means; wherein the resilient component for biasing rearward the front chuck is disposed within a tip member provided in the front of the axial tube, and a loosely fitted tube at least having a stopper portion at the rear end is provided in an opening portion of the tip member.
Further, according to a further aspect of this invention, there is provided a double chuck type mechanical pencil comprising: a front chuck for holding a lead provided at the extreme end of a tip member formed in the front of an axial tube; and a rear chuck for drawing out a lead to the front chuck by slidably moving a lead tank provided at the rear of the front chuck; wherein a loosely fitted tube is provided rotatably at the extreme end of the tip member.
Furthermore, according to another aspect of this invention, there is provided a double chuck type mechanical pencil comprising: a lead tank slidably provided within an axial tube; a rear chuck for drawing out a lead adapted to draw out a lead by slidably moving the lead tank; a chuck ring loosely fitted in the rear chuck; a rear resilient component for biasing rearward the lead tank and the rear chuck; and a front chuck for holding a lead provided in the front of the rear chuck; wherein a front resilient component for biasing rearward the front chuck is disposed within a tip member provided in the front of the axial tube, and a loosely fitted tube at least having a stopper portion at the rear end is rotatably provided in an opening portion of the tip member.
REFERENCES:
patent: 271439 (1883-01-01), Eybel
patent: 3437413 (1969-04-01), Parker
patent: 4720203 (1988-01-01), Shimada
patent: 1090138 (1955-08-01), None
patent: 7-228087 (1995-08-01), None
Kotobuki & Co. Ltd.
McGinn & Gibb PLLC
Walczak David J.
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