Cap for a writing means

Abstract: The present invention relates to a cap for a writing means provided with a suffocation preventive construction in which even if a curious child or the like should swallow accidentally to stop its throat or bronchus, a flow of air is sufficiently secured to avoid suffocation, and particularly to a cap for a writing means of a double-tube construction in which in a state where an air communicating portion (3) is secured in an inner peripheral surface of an outer tube (1) having front and rear portions opened, a closed-end tubular inner tube (2) is held coaxially within the outer tube (1), wherein a predetermined clearance (11) for communication between the air communicating portion (3) between the outer tube (1) and the inner tube (2) and a front-end opening side of the outer tube (1) is provided between an inclined lower end of a taper portion (6) provided in the front-end opening of the inner tube (2) and the inner peripheral surface of the outer tube (1), whereby the permeability is not impaired by ink adhered to the taper portion (6) during the process of mounting to the axial tube (4).

Description: BACKGROUND OF THE INVENTION 1. Field of the invention This invention relates to a cap for a pen, and particularly to a cap of a double-tube construction wherein an air communicating portion is secured in an inner peripheral surface of an outer tube having front and rear open ends and a closed-end tubular inner tube is fitted into and held coaxially within the outer tube, whereby a suffocation preventive construction results in which, even if a curious child or the like should swallow it accidentally, blocking its throat or bronchus, a flow of air sufficient secured to avoid suffocation can be maintained. 2. Description of prior art In the past, a cap of a double construction has been known which comprises an outer tube having open front and rear ends and a closed-end inner tube is held coaxially within the outer tube such that an air communicating portion is provided between the tubes. The inner tube has a taper portion for guiding the pen body into the inner tube during the mounting of the pen to the cap (disclosed, for example, in Japanese Utility Model Laid-Open Nos. Hei 2-58981 and 4-117790). The conventional cap disclosed in the aforementioned Japanese Utility Model Laid-Open No. Hei 4-117790 is constructed such that the outer tube and the inner tube are integrally connected at a bridge portion. The front surface of the bridge portion facing the front-end of the outer tube comprises a taper portion enlarged and inclined from the front-end of the inner tube and the pen body is guided into the inner tube by the taper portion. The bridge portion is peripherally provided with several vent holes to provide a permeable cap in which the rear-end and the front-end are communicated, whereby even if a child should swallow it accidentally suffocation can be avoided. During the process for guiding the pen body into the inner tube, ink tends to be adhered to the taper portion, such adhesion being unavoidable. Accordingly, in the past, the ink adhered to the taper portion can flow (enter) into the vent holes of the bridge portion and becomes solidified to close the vent holes. That is, permeability of the cap can be impeded. Patent Application No WO 93/09960 discloses a cap of a double tube construction which is composed of an open ended outer tube and a closed end inner tube held coaxially within the outer tube to provide an air communicating portion between the tubes and there is a taper portion for guiding a pen into the inner tube during the process of mounting the cap on the pen. The cap has a predetermined clearance communicating with the air communicating portion. The clearance is defined by the inner peripheral surface of the outer tube and an inclined front end of the taper portion. The taper portion is enlarged and inclined towards the inner surface of the outer tube. The top end of the inner tube is fitted into a spider support at the top of the outer tube. That spider support has apertures to provide a part of the communicating portion, but if there is dimensional error between the inner tube and the spider, then the inner tube may not fit effectively in the spider. OBJECT AND SUMMARY OF THE INVENTION It is an object of the present invention to provide a cap of a double-tube construction in which an air communicating portion is provided between outer and inner tubes, which is not closed by ink deposits and in which the inner and outer tubes can be effectively fitted together. Other objects will become apparent from the ensuing detailed description and drawings. According to the present invention, there is provided a cap of a double tube construction for a pen having a pen body and an axial tube, said cap having a front end and a rear end and comprising an open ended outer tube and an inner tube having an open end and a closed end, the inner tube being fitted into the outer tube so as to be concentric therewith, an air communicating portion extending through the cap from front to rear and between the inner tube and the outer tube, said inner tube having a taper portion for guiding the pen body into the inner tube during the process of mounting the cap on the pen axial tube, and wherein there is a predetermined clearance connecting the air communication portion with the front end opening side of the outer tube and lying between the inner peripheral surface of the outer tube and an inclined lower edge portion of the taper portion, which lower edge portion is enlarged and inclined from the front end opening of the inner tube toward the front-end opening of the outer tube, characterised in that the air communicating portion from where it starts at the rear end of the cap comprises an annular opening in and extending over part of the length of the inner tube so that over said length that portion of the inner tube outwardly of the annular opening can absorb load stress because of dimensional error as the inner tube is fitted into the outer tube. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:- Fig. 1 is a longitudinal sectional view showing one example of an embodiment of a cap for a pen according to the present invention; Fig. 2A is a cross-sectional view taken along line IIA-IIA of Fig. 1; Fig. 2B is a cross-sectional view taken along line IIB-IIB of Fig. 1; Fig. 2C is a cross-sectional view taken along line IIG-IIC of Fig. 1; Fig. 2D is a cross-sectional view taken along line IID-IID of Fig. 1; Fig. 3A is a longitudinal sectional view showing the mounting of the cap to a pen; Fig. 3B is a longitudinal sectional view showing the cap mounted on the pen; and Fig. 4 is a longitudinal sectional view showing another embodiment of the cap for a pen according to the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to the drawings. Fig. 1 is a longitudinal sectional view of a cap according to one embodiment. The cap has a double-tube construction in which a closed-end inner tube 2 is held coaxially within an outer tube 1 having front and rear open ends. An air communicating portion 3 is secured between the inner tube 2 and the outer tube 1, and the front-end of the inner tube 2 is provided with a taper portion 6 for guiding a pen tip body 5 which projects from a fore-portion 4-1 of an axial tube 4, into the inner tube when the cap is mounted to the pen. The outer tube 1 is formed of a desired injection molding material such as synthetic resin and is in the form of a cylindrical tube having a predetermined length. Its inside diameter is substantially the same diameter as the outside diameter of a mounting portion 4-2 of the axial tube 4. Its front and rear portions of substantially constant wall thickness over the full length thereof are open, the rear-end opening being provided with a holding portion 1-1 for receiving and holding the inner tube 2 in coaxial manner. The front-end opening is provided in its inner peripheral surface with an annular stop portion 8 to be fitted over an annular fitting portion 7 of the mounting portion 4-2. The holding portion 1-1 is formed over a suitable axial range from the rear-end of the outer tube 1 toward the front-end to be slightly smaller in both inside and outside diameters than other portions, and a stop shoulder 10 is provided in the inner peripheral surface edge located on the front-end opening side. The inner tube 2 is likewise formed of a desired injection molding material such as synthetic resin and is in the form of a closed-end tube whose entire external shape is formed to be smaller than the inside diameter of the outer tube 1 and the interior 2-1 for is formed to be small toward the bottom portion and to gradually increase toward the front-end opening except the range in which the pen body 5 of the axial tube 4 is fitted where comes in close sealing contact with the projecting fore-portion 4-1. That is, the closed-end tube is formed to be fitted and placed in close contact under slight elastic function when fitted to the fore-portion 4-1. The wall thickness of the tube is made gradually thicker from the front-end toward the closed rear end. Its length is about half of the full length of the outer tube 1. A taper portion 6 enlarged and inclined toward the inner peripheral surface of the outer tube 1 is provided in the front-end opening. The inner tube is incorporated and fitted in the holding portion 1-1 of the outer tube 1 so that the former is coaxially held within the outer tube 1 so as to provide a required annular clearance 11 between the inner peripheral surface of the outer tube 1 and the inner tube 2 and the inclined lower end of the taper portion 6. The inner tube 2 is provided at the outer peripheral edge of the rear end thereof with a large-diameter collar portion 12 in contact with and stopped at the rear-end opening end of the outer tube 1 and at the inner peripheral surface of the front-end opening with an annular convex portion 15 in close contact with the outer peripheral surface of the fore-portion 4-1 of the axial tube 4 when the cap is mounted in the pen. The large-diameter collar portion 12 serves to cooperate with the stop convex portion 9 of the outer peripheral surface of the inner cylinder 2 when the cap is fitted to the outer tube the portion 9 is stopped at the stop shoulder 10 provided as an inner peripheral surface edge of the holding portion 1-1 so as to catch the inner tube 2 in an axial direction and to fixedly hold the inner tube 2 within the outer tube 1 in an axially immovable state, the collar portion 12 being provided on the outer peripheral edge of the rear end surface of the inner tube 2 so as to have a projecting outside diameter which is substantially the same as the outside diameter of the rear-end opening of the outer tube 1. The stop convex portion 9 is spaced from the collar 12 by an amount 1-1 is provided at the outer peripheral surface part from the large-diameter collar portion 2 toward the front-end opening of the inner tube comprising the axial length of the holding portion 1-1. The air communicating portion 3, a suffocation preventive means, and the closed rear end portion of the inner tube 2 defines a portion in that it has an open sectional area through which air fully flows to sufficiently secure a flow of air, even if a curious child or the like should swallow the cap accidentally, the air and communicating portion has a substantially crank-like configuration in longitudinal section. This comprises a rear-side communicating portion 3-1 provided coaxially and annularly in the inner tube 2, and a front-side communicating portion 3-2 provided between the inner tube 2 and the outer tube 1 in the range from the rear-side communicating portion 3-1 to the front end opening of the inner tube 2 (see Fig. 1). The rear-side communicating portion 3-1 is provided with a coaxial annular opening at the latter half of full length of the inner tube 2 from the rear end surface of the inner tube 2 toward the front-end opening, in which a first communicating portion 3-10 opened in a suitable range from the rear end surface of the inner tube 2 and a second communicating portion 3-11 communicated and opened from the first communicating portion 3-10 toward the front-side communicating portion 3-2, bent and communicated in a peripheral direction through the front-side communicating portion 3-2 and a bent communicating portion 3-3. Portion 3-3 is defined in a peripheral direction by means of connecting longitudinal ribs 13 provided at several locations in a peripheral direction. The ribs are provided within the wall of the inner tube 2. The first communicating portion 3-10 has a range (length) of about half of the full length of the rear-side communicating portion 3-1 from the rear end surface of the inner tube 2 (see Fig. I and Fig. 2A) and provides an air inlet or outlet in the event that the cap blocks the throat or bronchus, and further, when the inner tube 2 is incorporated and fitted in the holding portion 1-1 of the outer tube 1 and held coaxially within the outer tube 1, it absorbs and relieves a load stress (internal stress) caused by a dimensional error relative to the inner tube 2 so as not to apply the load stress to the rear-end opening of the outer tube 1 as the holding portion 1-1. That is, in the case where a dimensional error caused by molding occurs in which an unnatural condition occurs during incorporation and fitting into the holding portion 1-1, because the inside diameter of the holding portion 1-1 is slightly smaller than the outside diameter of the outer annular portion 2-2. The inner tube 2 is annularly divided by the first communicating portion 3-10 and the outside diameter of the outer annular portion 2-2 is slightly larger than the inside diameter of the holding portion 1-1, the load stress caused by the dimensional error is absorbed and relieved by an escape (elastic deformation) of the outer annular portion 2-2 toward the first communicating portion 3-10 side whereby a damage such as a crack caused by the load stress from the open end edge is not imparted to the rear end opening of the outer tube 1, and the inner tube 2 can be incorporated and fitted into the holding portion 1-1 and fixedly held positively within the outer tube 1. On the other hand, over the second communicating portion 3-11 there are two connecting longitudinal ribs 13 opposedly provided on the circumference with spaces between to communicate the first communicating portion 3-10 with the front-side communicating portion 3-2 (see Fig. 1 and Fig. 2B). The front-side communicating portion 3-2 is provided with a required open sectional area between the outer peripheral surface of the inner tube 2 over the length leading to the front-end opening of the inner tube 2. Communication through the bent communicating portion 3-3 is between the second communicating portion 3-11 of the rear-side communicating portion 3-1 and the inner peripheral surface of the outer tube 1. As a result in the throat or bronchus should be blocked by the cap, air having passed through the clearance 11 between the inclined lower end of the taper portion 6 and the inner peripheral surface of the outer tube 1 is led to the rear-side communicating portion 3-1 through the bent communicating portion 3-3 and air having passed through the bent communicating portion 3-3 from the rear-side communicating portion 3-1 is led to the front-end opening side of the outer tube 1 through the clearance In the drawings, the reference numeral 14 designates longitudinal ribs provided on the outer peripheral surface of the front-end of the inner tube 2 to define the front-side communicating portion 3-2 in relation to the inner peripheral surface of the outer tube 1. The longitudinal ribs 14 are integral with the outer peripheral surface of the inner tube 2 over the range from the respective connecting longitudinal ribs 13 for peripherally defining the second communicating portion 3-11 of the rear-side communicating portion 3-1 toward the annular convex portion 15 on the inner peripheral surface of the inner tube 2 (see Fig. 1 and Fig. 2C). Ribs 14 serve to maintain constant over a long period of time elastic engagement with the outer peripheral surface of the fore-portion 4-1 from which the pen body 5 projects. That is, the longitudinal rib 14 can prevent, from the outer peripheral surface, the lowering of the elastic function of the inner tube 2 which possibly occurs due to the repetitious enlarged elastic deformation every mounting and removal from the axial tube 1. This ensures that the inner tube 2 can be always placed in close contact and fitted in the fore portion 4-1 with high airtightness required prevent volatilization of ink from the pen body 5 to be sealed. The taper portion 6 has an annular inclined edge portion 6-1 enlarged and inclined toward the inner peripheral surface of the outer tube 1 at the front end of the inner tube 2. It has an inner inclined surface (see Fig. 1 and Fig. 2D) so that when mounting to the outer tube 1, the pen body 5 is guided to the inner hole 2-1 of the inner tube 2 (the state of Fig. 3A to the state of Fig. 3B). The annular inclined edge portion 6-1 is projected at a suitable inclined angle from the front-end opening of the inner tube 2 toward the vicinity of the inner peripheral surface of the outer tube 1 to provide a required clearance 11 between the inclined outer peripheral surface and the inner peripheral surface of the outer tube 1. This provides communication between the front-side communicating portion 3-2 and the open front-end of the outer tube 1. Further, the annular inclined edge portion 6-1 is formed at the inclined lower end thereof with a liquid stopping flat portion 16 having a suitable annular width so that adhered ink which flows down from the inclined lower end toward the front-end opening side of the outer tube 1 along the taper portion 6 is prevented from moving toward the clearance 11. That is, adhered ink which flows down along the taper portion 6 is drops from the liquid stopping flat portion 16 to the front-end opening side of the outer tube 1 keeping the clearance clear (the state indicated by the two-dot chain line in Fig. 3B). Thus, during the process of mounting the cap to the axial tube 4, the pen body 5 is guided and led to the inner hole 2-1 of the inner tube 2 while contacting with the taper portion 6 (the state of Fig. 3A). Any ink adhered to the taper portion 6 flows to the liquid stopping flat portion 16 on the inclined lower end side along the taper portion 6 and drops to the front-end opening side of the outer tube 1 from the liquid stopping flat portion 16 for discharge (the state indicated by the two-dot chain line in Fig. 3B). Accordingly, the ink adhered to the taper portion 6 when mounted does not flow from the taper portion 6 into the clearance 11 which remains clear. In the event of the cap being swallowed, a flow of air is sufficiently secured to avoid suffocation, is maintained. Also, even if a curious child or the like should insert an elongated foreign matter or the like in the opening of the first communicating portion 3-10, it is caught by the bent communicating portion 3-3. Thus, the inserted elongated foreign matter does not completely creep (enter) through the air communicating portion 3 comprising the rear-side communicating portion 3-1 and the front-side communicating portion 3-2 but quickly slips out of the opening of the first communicating portion 3-10. There is therefore provided a suffocation preventive construction which can avoid in advance a dangerousness cause by entry of the elongated foreign matter and in which the permeability is not impaired by entry of the elongated foreign matter. Fig. 4 shows another embodiment in which an annular inclined edge 6-1 provided with a taper portion 6 formed separately from the inner tube 2 and mounted on the front-end of the inner tube 2 by means of a suitable mounting method such as press-fit, screwing or adhesives. This embodiment is fundamentally the same in constitution as that of the embodiment previously described except that the separately formed annular inclined edge 6-1 is mounted on the inner tube 2. Therefore, the same constituent parts are indicated by the same reference numerals and details thereof are omitted. The annular inclined edge 6-1 is molded of the same or different injection molding material as that of the inner tube 2, and is mounted to form a predetermined clearance 11 relative to the inner peripheral surface of the outer tube 1. If there occurs a dimensional error caused by molding such that the inside diameter of the outer tube is slightly smaller than the outside diameter of the inner tube, or the outside diameter of the inner tube is slightly larger than the inside diameter of the outer tube, such a slight dimensional error is absorbed and relieved by the rear-end communicating portion of the air communicating portion being provided coaxially and annularly from the closed rear end surface of the inner tube toward the front-end opening side. That is, the inner tube can be incorporated and fitted into the outer tube without applying the load stress (internal stress) caused by the dimensional error when incorporated into the outer tube and damage such as a crack caused by the load stress to the rear-end opening of the outer tube is avoided. When the inner tube is incorporated as described above, the inner tube is incorporated and fitted into the outer tube till the large-diameter collar portion of the inner tube comes in contact with and stops at the rear-end opening of the outer tube. At the same time the stopping convex portion of the inner tube is stopped at the stopping shoulder of the outer tube. Thereby, the inner tube is firmly fixedly held in an immovable state, and therefore the inner tube cannot slip out of the outer tube. When the cap is mounted to the pen when can be maintained constant for a long period of time by the longitudinal rib and lowering of the elastic action by by the repetitious enlarged elastic deformation every mounting to and removal from the axial tube is prevented by the longitudinal rib on the outer peripheral surface of the inner tube. Having described specific preferred embodiments of the invention with reference to the accompanying drawings, it will be appreciated that the present invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one of ordinary skill in the art without departing from the scope of the invention as defined by the appended claims.

Claims: A cap of a double tube construction for a pen having a pen body (5) and an axial tube (4), said cap having a front end and a rear end and comprising an open ended outer tube (1) and an inner tube (2) having an open end and a closed end, the inner tube (2) being fitted into the outer tube so as to be concentric therewith, an air communicating portion (3) extending through the cap from front to rear and between the inner tube (2) and the outer tube (1), said inner tube (2) having a taper portion (6) for guiding the pen body (5) into the inner tube (2) during the process of mounting the cap on the pen axial tube (4), and wherein there is a predetermined clearance (11) connecting the air communication portion (3) with the front end opening side of the outer tube (1) and lying between the inner peripheral surface of the outer tube (1) and an inclined lower edge portion (6-1) of the taper portion (6), which lower edge portion (6-1) is enlarged and inclined from the front end opening of the inner tube (2) toward the front-end opening of the outer tube (1), Characterised in that the air communicating portion (3) from where it starts at the rear end of the cap comprises an annular opening (3-10) in and extending over part of the length of the inner tube (2) so that over said length that portion (2-2) of the inner tube (2) outwardly of the annular opening (3-10) can absorb load stress because of dimensional error as the inner tube is fitted into the outer tube (1). A cap for a pen according to claim 1, wherein the taper portion (6) is provided at the inclined lower end with a liquid stopping flat portion (16) having a suitable annular width capable of keeping liquid spaced relative to the clearance (11) A cap for a pen according to claim 1, wherein the air communicating portion (3) is formed to be of a substantially cranked configuration in longitudinal section comprising a rear-side communicating portion (3-1) provided coaxially and annularly in the inner tube (2) in a suitable range from the closed end of the inner tube (2) toward the front-end and a front-side communicating portion (3-3) provided between the inner tube (2) and the outer tube (1) peripherally bent and communicating with the rear-side communicating portion (3-1) in the range from the rear-side communicating portion (3-1) to the front-end opening of the inner tube (2). A cap for a pen according to claim 3, wherein the inner tube (2) is provided at the rear end at the outer peripheral edge thereof with a large diameter collar portion (12) in contact with and stopped at the rear-end surface of the outer tube (1), and the outside diameter of the inner tube (2) over said portion (2-2) from the large-diameter collar portion (12) is formed to have the size capable of being fitted into the outer tube (1). A cap for a pen according to claim 4, wherein a stopping convex portion (9) is provided at an outer peripheral surface part spaced from the large diameter collar portion (12) toward the of the inner tube (2), and a stopping shoulder (10) for stopping said stopping convex portion (9) is provided on the inner peripheral surface of the outer tube (1) A cap for a pen according to claim 1, wherein peripheral several longitudinal ribs (14) are provided on the outer peripheral surface of the inner tube (2). A cap for a pen according to claim 1, wherein the clearance (11) is an annular opening.

Inventors: ISHIKAWA SHINICHI, NISHIMURA MAKOTO, ISHIKAWA, SHINICHI, NISHIMURA, MAKOTO, Ishikawa, Shinichi, c/o Zebra Co., Ltd., Nishimura, Makoto, c/o Zebra Co., Ltd.
Applicants: ZEBRA CO LTD, ZEBRA CO., LTD.
Application year: 1997
Main classification: B43K23
IPC codes: B43K23