Mitsubishi Pencil Kabushiki Kaisha

Yojiro Sano

Kazuhiko Furukawa

Takeshi Kobayashi

Hiroaki Koyama

Yosuke Mito

Provided is a writing instrument comprising an ink tank, an ink holder which can hold an ink, a pen tip, an ink guiding part for guiding the ink in the ink tank to the pen tip and an ink occlusion body which can feed the ink to the ink guiding part and which has an outer skin, wherein through parts are provide in the outer skin of the ink occlusion body.

Production processes for writing instrument and ink occlusion body

A writing instrument cap having a clip as a separate part. The clip attachment, to which the clip is fitted, is projectively formed on the outer periphery of the cap. The clip attachment is formed with a vent hole penetrating between the interior and exterior of the cap and raised portions for attachment of the clip. The raised portions are provided on both sides of the vent hole, with respect to the circumference of the cap. When the clip is attached to the clip attachment, the clip covers the clip attachment and the vent hole and creates a clearance between the clip interior and the clip attachment so as to establish an air passage that communicates between the vent hole and the outside atmosphere.

Writing instrument cap

A writing instrument includes a front barrel and an ink tank. When, with a rear barrel for accommodating the ink tank removably fitted on the ink tank, a cap formed to cover the front barrel is fitted on the front barrel, the cap is positioned and fastened by abutment of the opening end of the cap. The cap has a hollow for accommodating a point assembly. The inside diameter of the hollow exceeds the outside diameter of the front barrel and the outside diameter of a rear end of the rear barrel. A barrel hold is formed along the circumference on the inner wall portion of the cap, so that the barrel hold grips the outer periphery of the rear end of the rear barrel. A guide portion is formed on the inner wall portion of the cap, closer to the front side than the barrel hold, to restrain over insertion of the rear end of the rear barrel into the cap. A writing instrument cap is assembled of a cap body and a clip by engaging an engaging portion formed on the cap body and a hooking portion formed in the clip, and is constructed so that engagement becomes gradually tight as the clip is slid along the axis from a tacking position.

Writing instrument, writing instrument cap and method of assembly of a writing instrument cap

In a free-ink type collector writing instrument, a collector ( ) is formed with a passage hole ( ) for providing commutation between the interior and the outside air so as to prevent the point assembly from being affected by the variation in inner pressure upon freezing or upon increase or decrease in pressure. At the same time, the passage hole is constructed in a shape so as not to present a stronger capillary attraction than that of an air/liquid exchanger ( ) and than that of an ink feeder portion ( ), whereby the problem of exudation leakage over time can be prevented.

Collector type writing implement

In a writing instrument with a collector of the present invention, an ink absorber made up of a fabric sliver etc., capable of keeping ink therein is disposed inside the ink tank and is connected to the center core, longitudinal groove or the like as an ink feeder portion. The ink absorber is adapted to have a length at least reaching to a position more rearwards than the approximate center of the ink tank and has an outside diameter that is sized to be smaller than the inside diameter of the ink tank so as to create a space around itself for permitting free-state ink to move freely while the collector has a lead portion for establishing connection enabling ink to be led from the ink absorber to the air/liquid exchanger. Specifically, the lead portion of the collector may be configured of a projecting portion directly inserted into and connected with the ink absorber and a lead channel formed on the projecting portion. Alternatively, the lead portion may be formed, instead of being directly inserted to or connected with the ink absorber, by providing an ink lead channel capable of leading ink, which is connected to the center core, longitudinal groove or the like as an ink feeder portion that is connected to the ink absorber.

A collector type writing instrument which is formed with a sectioning portion for substantially separating its ink tank and a snorkel having a tubular vent portion for establishing air communication between the front and rear spaces divided by the sectioning portion, wherein at least one ink conduit of a size smaller than that of the vent portion is formed in the sectioning portion. Further, a clearance portion allowing for ink and air bubbles to move therethrough is provided between the collector and snorkel. In addition, the parts present from the sectioning portion to the rear end of the collector are laid out so that ink will be able to spread and wet the surfaces of the parts other than the ink tank. It is also preferable that the end of the tubular vent portion of the snorkel is cut so as to enlarge the opening. The writing instrument is configured so as to satisfy the relations Ts>Is and Tt>It, where 'Ts' is the total minimum cross-section of the vent portion, 'Tt' is the total distance of the vent portion, &lsquo;Is&rsquo; is the total minimum cross-section of the ink conduit and &lsquo;It&rsquo; is the total distance of the ink conduit.

Collector type writing instrument

In a free-ink type collector writing instrument, the collector is formed with a partitioning portion for substantially shutting off the ink tank from the outside air, auxiliary retaining grooves are formed on the ink tank side with respect to the air/liquid exchanger of the partitioning portion while main retaining grooves are formed on the front side with respect to the air/liquid exchanger of the partitioning portion, a wide groove formed across the auxiliary retaining grooves for connecting the air/liquid exchanger and the ink tank is formed with a narrow groove extending from the air/liquid exchanger side to the ink tank side and lateral grooves capable of leading ink into the auxiliary retaining grooves. It is further effective if the capacity 'ie' of the auxiliary retaining grooves and the capacity 'is' of the main retaining grooves are designed so as to satisfy a relation &lsquo;is>ie>0.05&middot;is&rsquo; or if effective partitioning portion grooves are formed.

A collector type writing instrument including: a collector for temporarily storing ink therein upon a change in inter pressure, a sectioning portion for substantially separating its ink tank for storing ink, and a snorkel having a vent portion for establishing air communication between the front and rear spaces divided by the sectioning portion or an ink absorber for reducing the inner tank volume, wherein the snorkel or the cladding of the ink absorber is molded of the same material as the collector or the ink tank is or is subjected to the same wettability reforming treatment as the collector or the ink tank is.

A direct-feed type writing implement having two ends includes an ink tank and a pair of writing points, arranged at opposite ends of the ink tank. An ink collector is provided for each writing point. An air/liquid exchanger adjusts the internal pressure inside the ink tank by use of capillarity. An ink feeder is provided for each writing point. Each ink feeder includes a center core for feeding ink to the writing point. Air is inhibited from flowing into the ink tank through the ink collector air/liquid exchanger located at one end while the pen is being used for writing at the opposite end.

Double ended direct-feed type writing implement

A collector for adjusting internal pressure of a writing implement offers improvements in deficiency prevention performance such as the capability of preventing ink leakage from occurring due to influence of the ambient pressure being varied during usage or when its cap is put on and off, the capability of preventing ink from erupting or leaking forward when the implement has been stored at a shop for a long period, and which still provides smooth writing comfort during writing. A collector ( ) introduces ink through an ink channel ( ) by the function of capillary action and temporarily holds ink in ink retaining grooves ( ) and establishes air passage in the axial direction and radial direction by the combination of the air channel ( ) and retaining grooves ( ). The air channel is continuously formed so as to zigzag with a multiple number of turns with respect to axial direction of collector ( ) by way of air channel parts ( and ) and connecting passages ( and ). This zigzagging configuration makes it possible to reduce ink eruption due to inrush of ink from the ink tank to the retaining grooves of the collector when a sharp change in temperature or pressure occurs.

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Tokyo, Japan

Yojiro Sano