Magnetic tape cassettes and processes for producing them Number:7,419,115 from the United States Patent and Trademark Office (PTO) owispatent

Title: Magnetic tape cassettes and processes for producing them

Abstract: The magnetic tape cassette has a base with an opening for forming a transparent window and a transparent resin-made window member to be installed in said opening. The window member is provided with an engaging unit which is to be fitted into the base at an angle and the base is provided with an engaging portion that is formed at an angle in correspondence to the engaging unit and the window member is installed in the opening by being fitted in at an angle.

Patent Number: 7,419,115 Issued on 09/02/2008 to Hiraguchi

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Inventors:	Hiraguchi; Kazuo (Kanagawa, JP)
Assignee:	FUJIFILM Corporation (Tokyo, JP)
Appl. No.:	11/372,195
Filed:	March 10, 2006

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	10183372	Jun., 2002	7035048

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Foreign Application Priority Data

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Jul 02, 2001 [JP]			2001-200695

Current U.S. Class:	242/347 ; 360/132
Current International Class:	G11B 23/04 (20060101)
Field of Search:	242/347,348 360/132

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References Cited [Referenced By]

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U.S. Patent Documents

4545483	October 1985	Shiba et al.
5054616	October 1991	Gelardi et al.
5581430	December 1996	Schoettle et al.
6556379	April 2003	Ashikawa

Foreign Patent Documents

	1 102 265		May., 2001		EP
	57-179972		Nov., 1982		JP
	61-156074		Sep., 1986		JP
	01072377		Mar., 1989		JP
	05-182399		Jul., 1993		JP
	05-298852		Nov., 1993		JP
	06-005041		Jan., 1994		JP
	06-349226		Dec., 1994		JP
	07037358		Feb., 1995		JP
	07-334964		Dec., 1995		JP
	2000173227		Jun., 2000		JP
	2000215636		Aug., 2000		JP
	WO 94/16012		Jul., 1994		WO

Primary Examiner: Nguyen; John Q.
Attorney, Agent or Firm: Sughrue Mion, PLLC

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Parent Case Text

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This is a divisional of application Ser. No. 10/183,372 filed Jun. 28, 2002 now U.S. Pat. No. 7,035,048. The entire disclosure of the prior application Ser. No. 10/183,372 is considered part of the disclosure of the accompanying divisional application and is hereby incorporated by reference.

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Claims

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What is claimed is:

1. A magnetic tape cassette having: a base with an opening for accommodating a transparent window and at least one reel of magnetic tape; and a transparent resin-made window member to close said opening in said base, wherein said base and said window member are each composed of materials having no compatibility or having an extremely low degree of compatibility to each other for ultrasonic or thermal welding, said opening in said base has a ridge that engages said window member, said window member has a recess in at least one of two sets of opposed sides which fit said ridge on said base, and wherein said ridge on said base is fitted into said recess in said window member, said base comprising an inner peripheral wall forming the opening, said inner peripheral wall having said ridge, such that portions of said inner peripheral wall above and below said ridge face into the opening, said recess of said window member engages said ridge, such that portions of said window member above and below the recess abut respectively against said portions of said inner peripheral wall above and below said ridge, and said window member has a first side and second side which extend across the opening, and said recess of the window member engaging said ridge is positioned such that a shortest distance from said recess to said first side of said window member is shorter than a shortest distance from said recess to said second side of said window member.

2. The magnetic tape cassette of claim 1, wherein said ridge is block shaped.

3. The magnetic tape cassette of claim 1, wherein said base is thicker than a thickest portion of said window member.

4. The magnetic tape cassette according to claim 1, wherein both of said first side and said second side of said window member are recessed into said opening.

5. The magnetic tape cassette according to claim 1, wherein said first side which is recessed includes a projection extending from a periphery of said window member, which is operable to be broken off upon an application of force to said window member.

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Description

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BACKGROUND OF THE INVENTION

This invention relates to magnetic tape cassettes having an easy-to-separate transparent window and processes for producing them. The invention particularly relates to magnetic tape cassettes that have a transparent window formed of a transparent resin (plastic) window member in the upper half of the cassette in such a way that when the cassette is discarded after use, the window member can be easily separated from the opening in the base (the body of the upper half) so that the base and the window member can individually be recovered as recyclable feeds as well as a process for producing the magnetic tape cassettes.

The invention also relates to shaped resin articles that are so designed that members of different materials can be easily separated from each other, as exemplified by magnetic tape cassettes which are so designed that the transparent window in the housing (cassette case) through which the user can check the residual amount of tape (visually) is easily separable from the housing (or its base).

The invention also relates to a method for multi-color molding of resin products, particularly of magnetic tape cassettes which are so designed that the transparent residual tape check window in the housing (cassette case) is easily separable from the housing.

The invention further relates to a method for destructing and separating parts made of dissimilar materials which is particularly applicable to the magnetic tape cassette and by which the transparent residual tape check window in the housing (cassette case) of the magnetic tape can be easily separated from the housing which is made of a dissimilar material than the transparent window.

As an introduction to the specific description of the invention, magnetic tape cassettes are well known which are of such a type that a web of magnetic tape is wound around a pair of take-up hubs which are rotatably housed in the housing (cassette case). This magnetic tape cassette has a transparent window formed in the upper half so that the user can see through it to check the residual amount of the magnetic tape wound around the right and left take-up hubs. Obviously, in order to eliminate the waste of resources and save them or protect the environment, it is most desirable that the upper half of the magnetic tape cassette, when discarded after use, should be disassembled into its body (base) and the transparent window member so that they can be recycled as new feeds.

Considering these points, the present invention provides easy-to-disassemble magnetic tape cassettes (or their upper half) and processes for producing them, shaped resin particles such as magnetic tape cassettes, a method for multi-color molding of resin products such as magnetic tape cassettes (or their upper half) and a method for destructing and separating parts of dissimilar materials such as the transparent window and the housing (cassette case) of magnetic tape cassettes.

With the recent concern over environmental problems, people are worrying about the adverse effects that may be caused to the environment by increased dumping of resins (plastics), composites and other materials. Under the circumstances, reducing the impact on the environment by either minimizing wastes or dumping them in forms that are not deleterious to the purpose of preserving the environment is becoming increasingly important. To this end, efforts are being made to integrate industrial products into the circulating system of the society at large by, for example, ensuring that they can be easily disassembled into various parts by materials type so that the latter can be recycled as much as possible.

Two types of magnetic tape cassette are known as image recording and reproducing tape cassettes that are used in consumer or professional video tape recorders or video cameras, and also as large-capacity recording media that are used to back up data in external storages in computers and the like; the first type comprises magnetic tape wound around a pair of take-up hubs placed rotatably in a cassette case consisting of an upper half and a lower half (which is hereunder referred to simply as a housing) and the second type comprises magnetic tape wound around a single tape reel also encased rotatably in a housing. Known examples are magnetic tape cassettes the structural and dimensional specifications of which are described in JIS X6127, X6129, X6130, X6171 and X6172, as well as in ECMA-288, etc. Those various types of magnetic tape cassette are designed as complex structures formed of various metallic members in combination with various synthetic resin members depending upon the performance and shapes required of the parts of which they are made.

The various types of magnetic tape cassette mentioned above have a window formed in one or more openings in the top plate of the upper half and in order to ensure that the user can externally check the amount, state and other parameters of the magnetic tape that has been taken up by the hubs or the tape reel in the cassette case, the window is formed by fitting a transparent or translucent window member in the opening or openings. The windows are made of various resin materials depending upon the impact strength, wear resistance, durability and other characteristics required of the respective magnetic tape cassettes. For example, window members formed of an AS resin may be fitted in cassette cases formed of an ABS resin; alternatively, all parts including the cassette case and the window member may be formed of a PS resin. Thus, magnetic tape cassettes are made of various resins depending upon the required performance and shapes and are not formed of unified materials.

A common magnetic tape cassette may diagrammatically be shown in perspective in FIG. 65. As shown, the magnetic tape cassette generally indicated by 90 consists of an upper half 91 and a lower half 92 that combine to form the cassette case as the housing. A slider 93 is fitted to the underside of the lower half 92 and a lid 94 is provided at the front face of the cassette (which is closer to the viewer). The slider 93 can slide back and forth on the underside of the lower half 92 so that when the cassette is not in service, the slider prevents dust from getting into the cassette by closing the opening in the lower part of the cassette case. The lid 94 on the upper half 91 is pivotally mounted on a shaft 94a so that it can open or close the front face of the cassette.

The housing of the magnetic tape cassette 90 contains magnetic tape 95 as it is wound around a pair of take-up hubs. The upper half 91 has a transparent window 96 through which the residual amount of tape in the magnetic tape cassette 90 can be checked as when it has been taken out of the deck (not shown).

As already mentioned, the respective parts of the magnetic tape cassette are formed of synthetic resins. Specifically, members that require sliding properties (wear resistance) are molded of POM (polyacetal) resin; if cost performance is important, Si (silicon) is added to PS (polystyrene) to prepare a resin molding material; if strength is an important factor, ABS (acrylonitrile-butadiene-styrene) resin is employed.

Speaking of video cassettes which are generally molded of ABS, the transparent residual tape check window is often molded of ABS-compatible resins such as AS (acrylonitrile-styrene) and PMMA [poly(methyl methacrylate)]. This is because the window and the cassette case are formed by two-color molding (two-layer molding) and subsequently bonded by welding.

The molding of the magnetic tape cassette under consideration, especially the molding of the upper half 91 and the window 96 is conventionally performed as follows.

As shown in FIG. 66A, a die assembly 100 for molding the upper half 91 and the window member 96 is basically composed of an upper die 102, a lower die 104 and a moving (sliding) core 106. The upper die 102, the lower die 104 and the moving core 106 define a space 108, into which a molten resin [e.g. ABS (acrylonitrile-butadiene-styrene) resin] is injected to mold the upper half 91.

Then, as shown in FIG. 66B, the moving core 106 is allowed to descend by a distance equal to the thickness of the window member 96; into the resulting space 110, a transparent resin [e.g. AS (acrylonitrile-styrene) resin] is injected to mold the window member 96.

Conventionally, as shown in FIGS. 66A and 66B, the edges of the moving core 106 are cut out at an angle (beveled) so that the area of contact between the window 96 and the upper half 91 is sufficiently increased to achieve more effective bonding of the two components after molding.

FIG. 67 shows in perspective the upper half of the cassette case of the prior art magnetic tape cassette with part taken away after it has been cut through the transparent window, and FIG. 68 is a section of FIG. 67 which has been taken through the transparent window. In order to fabricate the upper half 80 of the conventional cassette case, the body 82 serving as the base is first provided; then an opening 82a is made in the body 82 to provide an area in which a transparent window member 84 can later be fitted and a window frame 82b is formed around the opening 82a to support the window member 84; subsequently, the window member 84 is fitted into the opening 82a in the body 82 and welded to the supporting window frame 82b by ultrasonic welding or some other method.

The method of transparent window fabrication which is illustrated by FIGS. 67 and 68 is convenient and suitable for mass production of cassette cases. However, if the upper half 80 of the cassette case discarded after use is to be disassembled into its body 82 and the window member 84 so that they can be recycled as new feeds, a serious problem arises, i.e., since the transparent window 84 is welded to the body 82, it is very difficult to disassemble the upper half 80 without breaking either the body 82 or the window member 84.

Even if the upper half 80 is disassembled by breaking either its body 82 or the window member 84, it is practically impossible to ensure that both are positively separated from the welded area and part of the window member 84 will remain firmly adherent to the upper half's body 82 or vice versa. Under these circumstances, if an attempt is made to recycle the upper half's body 82 and the window member 84 as respectively new feeds, the two components inevitably occur as a mixture--part of the window member 84 firmly adheres to the upper half's body 82 and part of the body 82 firmly adheres to the window member 84 and it has been unavoidable that the recycled feeds have only low purity.

The transparent window as a component of the cassette case is included as part of the upper half 80 and must impart air-tightness for dust prevention and other purposes. In addition, the cassette case involves manual handling at various stages of its use including carrying, storage and loading onto the recording and reproducing apparatus and it must have sufficient strength that it will not break or become dislodged during handling.

As already mentioned, the conventional magnetic tape cassette molded by the method illustrated in FIGS. 66A and 66B features a very strong bond between the transparent window and the housing in order to maintain the strength of the cassette case and considerable force is usually required to separate the window from the housing by hand. Because of this strong bond, it has been difficult to achieve selective recovery of dissimilar materials, particularly ABS from AS or PMMA. The high peel strength of the conventional magnetic tape cassette is desirable from the viewpoint of ensuring that it performs the intended functions; however, its shape does not allow easy disassembling into the window and the housing.

Furthermore, if the user attempts to separate the window from the housing by force, he has to break the window but if it does not break easily and neat, he may be hurt by the shattered pieces of window. Simply cutting slits or otherwise rendering the window easily breakable is not capable of producing a sufficiently dust-proof cassette case. The window once bonded firmly to the upper half does not break easily and if it is destroyed by force, it will partly remain adhering to the housing; this is better than what has been attained in the prior art but the separation is by no means complete. If the window is not collected as a separate entity from the housing or if the separation is not complete, the mixing of dissimilar materials makes it difficult to recycle the respective parts and regenerate materials of good quality (this type of recycling is called "materials recycling") that sell at competitive price. A need therefore arises to increase the precision in the separation technology.

Thus, it has been desired to design a magnetic tape cassette that permits easy separation of the window from the housing without compromising the dust-proofness of the cassette case. Common resin products have a similar need and they should desirably be so designed that various parts can be easily collected as separate entities, thereby making more parts recyclable.

As already mentioned, there is an increasing demand for designing industrial products that can be manufactured by making effective use of limited resources of the Earth and which can be disposed of in an environment friendly manner. This is one of the reasons why the components or constituent materials of magnetic tape cassettes that find massive use in a wide range of applications are desirably recycled to realize saving of resources and disposed of without increasing the impact on the environment.

Resins of which the magnetic tape cassettes are made can generally be recycled either as members, parts or resin feeds (materials recycling) or as fuels (thermal recycling).

Materials recycling presents no big problems in saving resources and reducing the environmental impact. On the other hand, thermal recycling involves the use of thermal energy and is not effective for preventing global warming since an increasing amount of heat is dissipated to the environment in the recycling process. Therefore, the magnetic tape cassettes are desirably made of members, parts or materials none or only a few of which need be subjected to thermal recycling.

From these viewpoints, the window member to be fitted in the upper half of the magnetic tape cassette should desirably satisfy the requirements of the saving resources, conserving the Earth's environment and not contributing to global warming.

The present invention has been accomplished under these circumstances and its primary objective is to solve the aforementioned problems of the prior art by providing a magnetic tape cassette which, in the case of disassembling a discarded magnetic cassette into the base (the body of the upper half) and the window member and recycling the respective parts as feeds for the manufacture of additional products, can be disassembled in an easy and safest way, preferably easily without breaking, and in an efficient way and which is also characterized in that no part of the window member will remain adhering to the base or vice versa, that the separated base or window member can be recycled as a feed for additional products without suffering a drop in purity, and that it has a transparent window which is sufficiently air-tight and strong to provide it with adequate air-tightness and strength. The invention also aims at providing a process for producing the magnetic tape cassette.

Another object of the invention is to provide a magnetic tape cassette of such a structure that, in the case of disassembling a discarded magnetic tape cassette into the upper half's body and the window member, utmost safety is assured in the disassembling operation, as well as a process for producing the magnetic tape cassette.

The second objective of the present invention is to provide a method for multi-color molding of resin products such as magnetic tape cassettes which can solve the aforementioned problems of the prior art by permitting easy separation and recovery of various parts of magnetic tape cassettes and other resin products so that they can be put to second use.

The third objective of the present invention is to provide shaped resin articles which can solve the aforementioned problems of the prior art by permitting easy separation and recovery of various parts of magnetic tape cassettes and other resin products so that they can be put to second use.

The fourth objective of the present invention is to provide a magnetic tape cassette which is effective for conserving the Earth's environment and preventing global warming by permitting less heat to be given off during recycling, thereby solving the aforementioned problems of the prior art.

Another object of the invention is to provide a magnetic tape cassette which, even in a less likely case where part of a discarded magnetic tape cassette is subjected to thermal recycling, can be processed emitting a smaller amount of heat during the recycling process.

The fifth objective of the present invention is to provide a method for breaking and separating dissimilar materials which solves the aforementioned problems of the prior art by permitting easy separation and recovery of various parts of shaped articles made of dissimilar materials, as in the case of magnetic tape cassettes and other resin products, so that they can be put to second use.

These objects and objectives of the present invention will become apparent as the following description evolves.

In order to attain the primary objective described above, according to a first aspect of the invention, there is provided a magnetic tape cassette having:

a base with an opening for forming a transparent window; and

a transparent resin-made window member to be installed in the opening, wherein

the window member is provided with engaging means which is to be fitted into the base at an angle and the base is provided with an engaging portion that is formed at an angle in correspondence to the engaging means, and wherein

the window member is installed in the opening by being fitted in at an angle.

The window member has preferably a step on perimeter or in end portions in order to prevent dust.

Further, depth of the engaging portion of the base is preferably greater than height of the engaging means provided on the window member.

In order to attain the primary objective described above, according to a second aspect of the invention, there is provided a magnetic tape cassette having:

a base with an opening for forming a transparent window; and

a window member to be installed in the opening, wherein

the base has in at least a part of an inner circumferential area of the opening an adequately rigid upper window frame, an elastically deformable lower window frame and a temporary fitting portion that allows the window member to be inserted between the upper and lower window frames,

the window member being made of a transparent resin that has no compatibility or has only low compatibility with a material of which the base is made, and

the upper window frame or the lower window frame around the opening or the window member is provided with a projection in a position where they contact each other, and wherein

the window member being inserted into the temporary fitting portion so that the lower window frame deforms elastically to achieve temporary joint between the window member and the base, and

ultrasonic waves or heat is allowed to act on the temporary joint.

According to the second aspect of the invention, there is also provided a process for producing a magnetic tape cassette having a base with an opening for forming a transparent window and a window member to be installed in the opening, comprising the steps of:

molding the window member of a material having no compatibility or having an extremely low degree of compatibility with the material of which the base is made;

molding the base in such a way that the base has in at least a part of an inner circumferential area of the opening an adequately rigid upper window frame, an elastically deformable lower window frame and a temporary fitting portion that allows the window member to be inserted between the upper and lower window frames, the base and the window member being molded to such that the upper window frame or the lower window frame around the opening in the base or the window member has a projection in a position where the upper window frame or the lower window frame contacts the window member;

inserting the window member into the temporary fitting portion around the opening in the base so that the lower window frame deforms elastically to achieve temporary joint between the window member and the base; and

allowing ultrasonic waves or heat to act on the temporary joint.

In order to attain the primary objective described above, according to a third aspect of the invention, there is provided a magnetic tape cassette having:

a base with an opening for forming a transparent window; and

a transparent resin-made window member to close the opening in the base, wherein

the base and the window member are composed of materials having no compatibility or having an extremely low degree of compatibility to each other, and wherein

the window member comprises a portion that is formed with a first sliding member of a die assembly for molding the base and a portion that is formed with a second sliding member of the die assembly, the window member having such a shape that the base is retained between the two portions.

According to the third aspect of the invention, there is also provided a magnetic tape cassette having:

a base with an opening for forming a transparent window; and

a transparent resin-made window member to close the opening in the base, wherein

the base and the window member are composed of materials having no compatibility or having an extremely low degree of compatibility to each other, the opening in the base ridges that engage the window member, the window member has recesses in at least one of two sets of opposed sides which fit the ridge on the base, and wherein the ridge on the base is fitted into the recess in the window member.

According to the third aspect of the invention, there is further provided a process for producing a magnetic tape cassette having a base with an opening for forming a transparent window and a transparent resin-made window member to close the opening in the base, comprising the steps of:

preparing a die assembly for molding the base which has a first sliding member which can be moved from one side of the base in order to form the opening and a second sliding member which can be moved from the other side of the base and which has at both ends recesses for providing the opening with ridges that engage the window member;

bringing the first sliding member into intimate contact with the second sliding member;

injecting a base forming material to mold the base having the opening;

causing the first sliding member and the second sliding member to be spaced apart; and

injecting into a resulting space a window member forming material that has no compatibility or has an extremely low degree of compatibility with the base forming material, whereby the window member is molded as an integral part of the base.

More specifically, the magnetic tape cassette according to the third aspect is of such a cross-sectional shape that it has recesses in the inner surfaces on both sides of the opening in the base, the recesses being interconnected by an edge portion. To manufacture the magnetic tape cassette having the base with this opening and the window member made of a transparent resin that closes the opening in the base, the following process is preferably employed: the base is molded with a die assembly having a first sliding member (cavity or core) that forms the recess in the front surface of the base and a second sliding member (cavity or core) that forms the recess in the back surface of the base and the opening, the first and second sliding members being both movable, and the first and second sliding members are advanced until they intimately contact each other and the recesses in the inner surfaces on both sides of the opening in the base and the edge portion interconnecting the recesses are molded, whereas the transparent window is molded with the same die assembly as above by injecting a transparent resin having no compatibility or having an extremely low degree of compatibility with the base molding resin into the space defined by retracting the first and second sliding members, whereupon the transparent window is molded as an integral part of the base.

In order to attain the second objective described above, according to a fourth aspect of the invention, there is provided a magnetic tape cassette having:

a resin-made base with an opening for forming a transparent window; and

a transparent resin-made window member to close the opening in the base, wherein

respective resin-made parts of the magnetic tape cassette including at least the base and the window member are molded in multiple colors with a single die assembly using at least two incompatible resin materials that are not adherent to each other and, thereafter,

the respective resin-made parts are demolded and recombined from predetermined directions, whereby

the respective resin-made parts are assembled together in one step.

In the second, third and fourth aspects, it is preferable that the base is made of an ABS resin and that the window member is made of a transparent AS resin.

In order to attain the second objective described above, according to the fourth aspect of the invention, there is also provided a method for molding a resin product in multiple colors using at least two resins, comprising the steps of:

molding respective parts of the resin product in multiple colors with a single die assembly using at least two incompatible resin materials that are not adherent to each other; and thereafter

demolding the respective parts and recombining the respective parts from predetermined directions, thereby assembling the respective parts together in one step to produce the resin product.

In order to attain the primary objective described above, according to a fifth aspect of the invention, there is provided a magnetic tape cassette having:

a base with an opening for forming a transparent window;

a transparent material-made window member to be installed in the opening; and

joining means provided on either the base or the window member or both in order to install the window member within the opening in the base.

In a first embodiment of the fifth aspect, it is preferable that the joining means comprises a first wedge-shaped projection on an inner perimeter of the base around the opening which forms the window and a second wedge-shaped projection on the outer perimeter of the window member, and that the first projection on the base is brought into engagement with the second projection on the window member, whereby the window is installed within the opening in the base.

In the first embodiment of the fifth aspect of the invention, it is preferable that the joining means comprises a window frame for supporting the window member on an inner perimeter of the base around the opening and an engaging pawl that is so shaped as to fit to the base and which holds the window frame of the base by engaging its lower edge, and that the engaging pawl of the window member is brought into engagement with the window frame of the base so that the window member is installed within the opening in the base.

Further, in the first embodiment of the fifth aspect of the invention, the joining means preferably comprises two sets of engaging members, one set consisting of the first wedge-shaped projection provided on the inner periphery of the opening in the base and the second wedge-shaped projection provided on the outer periphery of the window member and the other set consisting of the window frame provided on the inner periphery of the opening in the base and the engaging pawl provided on the outer periphery of the window member, and the first projection on the base is brought into engagement with the second projection on the window member whereas the engaging pawl on the window member is brought into engagement with the window frame on the base so that the window member is fitted into the opening in the base.

According to a second embodiment of the fifth aspect of the invention, a joint portion established by the joining means between the window member and the opening in the base has preferably a generally V-shaped cross section with an inclined portion.

Stated specifically, the cassette case according to the second embodiment of the fifth aspect of the invention is characterized in that the transparent window in the cassette case is one that is provided in the upper half of the cassette case in order to enable visual checking of the residual amount of magnetic tape as it is wound around take-up hubs, that the cassette case has the body of the upper half which serves as the base having the opening in which the transparent window is to be fitted and the window member that is made of a transparent resin and which closes the opening in the body of the upper half, and that the joint between the opening in the body of the upper half and the window member has a generally V-shaped cross section with an inclined portion.

With this design, the window member may be pushed at an angle from the inside, whereupon it becomes separable from the opening in the base. The generally V-shaped cross section with an inclined portion is preferably of such a shape that the opening in the base has an inwardly extending projection.

In the second embodiment of the fifth aspect of the invention, the term "generally V-shaped" (hereunder referred to simply as "V-shaped") refers to a state where two planes are opposed at an angle, at least one of which is parallel to the upper and lower surfaces of the upper half's body whereas the other plane forms a specified angle with the one plane. The specified angle refers to a range of angles over which smooth fitting can be accomplished upon pressing and the preferred value is typically at least 30 degrees.

In the second embodiment of the fifth aspect of the invention, it is also preferable that an inner perimeter of the opening in the base is shaped in a circular form, an outer perimeter of the window member is shaped in a circular form so that it can be installed with the circular opening in the base, and that the engaging means comprises an engaging projection provided on either the inner circular perimeter of the opening or the outer circular perimeter of the window member and an engaging portion provided on either the outer circular perimeter of the window member or the inner circular perimeter of the opening to come into engagement with the engaging projection, the window member being fitted into the opening in the base and rotated until it is secured in such a way as to close the opening.

Stated specifically, the magnetic tape cassette according to the second embodiment of the fifth aspect of the invention is one having a base with an opening and a window member made of a transparent resin that closes the opening in the base, characterized in that an engaging projection is provided on either the inner peripheral surface of the opening or the outer peripheral surface of the window member whereas an engaging portion that comes into engagement with the engaging projection is provided on either the outer peripheral surface of the window member or the inner peripheral surface of the opening and that the window member is fitted into the opening in the base and rotated to become fixed in position.

Preferably, the base is the body of the upper half of the magnetic tape cassette and the transparent window is provided in two positions that correspond to the take-up hubs in the magnetic tape cassette.

In a more preferred case, the engaging projection and the engaging portion to be provided on the inner peripheral surface of the opening and on the outer peripheral surface of the window member are such that the engaging projection is provided on the outer peripheral surface of the window member whereas the engaging portion in a helical or partially helical form is provided on the inner peripheral surface of the opening or that the engaging portion in a helical or partially helical form is provided on the outer peripheral surface of the window member whereas the engaging projection is provided on the inner peripheral surface of the opening and that the window member is fitted into the opening in the base and rotated so that it is screwed up to become fixed in position.

In order to attain the third objective described above, according to a sixth aspect of the invention, there is provided a shaped resin article composed of members made of different materials and which has a plate-form member integrated into a housing in such a way that the plate-form member and the housing can be easily separated from each other, wherein vertically offset projections are provided on each of the opposed sides of a portion of the housing which is to receive the plate-form member such that each end portion of the plate-form member can be held between an upper row of projections and a lower row of projections and wherein the plate-form member can be integrated by being inserted between the upper and lower rows of projections only from one direction with respect to the portion of the housing which is to receive the plate-form member.

The shaped resin article according to the sixth aspect of the invention is a magnetic tape cassette having a base with an opening and a window member made of a transparent material which is to be fitted into the opening in the base, characterized in that vertically offset projections are provided on each of the opposed sides of the opening in the base such that each end portion of the window member can be held between an upper row of projections and a lower row of projections and that the window member can be integrated by being inserted between the upper and lower rows of projections only from one direction with respect to the opening in the base.

In order to attain the primary objective described above, according to a seventh aspect of the invention, there is provided a magnetic tape cassette having:

a base with an opening for forming a transparent window;

and a transparent material-made window member to be installed in the opening, wherein

the window member is installed within the opening and

a manipulating engaging portion effective in the step of separating the transparent window is provided on the window member or in that area of the base which contacts the window member.

While the manipulating engaging portion may be provided in various areas, it is preferably in an end portion of the window member.

The manipulating engaging portion may be provided in various forms but it is preferably a groove that is provided in the base as an aid in dislodging an engaging means.

In order to attain the fourth objective of the invention, according to an eighth aspect of the invention, there is provided a magnetic tape cassette having:

a base with one or more openings for forming transparent windows; and

one or more transparent resin-made window members to be installed in the one or more openings, wherein

the window member is made of a biodegradable resin and fitted within at least one of the one or more openings in the base.

In order to attain the fifth objective of the invention, according to a ninth aspect of the invention, there is provided a method for destructing, separating and recovering two or more parts of a shaped resin article which have been molded of dissimilar materials, wherein one of the parts to be separated for recovery is provided with a specified mark in a specified position on the part which is related to the position of a gate on the part for injecting molding the part and which, if it is given an impact, becomes a start point for a crack to propagate toward the position of the gate and wherein upon application of an impact to the position of the specified mark, the parts molded of the dissimilar materials can be separated for recovery without using a special tool.

The shaped resin article is a magnetic tape cassette comprising a cassette case that has an upper half and a lower half joined together in a face-to-face relationship and which contains magnetic tape wound around a reel, characterized in that the body of the upper half serving as the base has an opening for forming a transparent window and a window member as a window constituting part made of a transparent material, the window member being provided with a specified mark in a specified position on the part which is related to the position of a gate on the part for injection molding the part and which, if it is given an impact, becomes a start point for a crack to propagate toward the position of the gate.

In each of the foregoing aspects of the invention, the base is preferably the body of the upper half and it is preferably the upper half that comprises this body and the window member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a magnetic tape cassette according to an example of a first embodiment of the fifth aspect of the present invention;

FIG. 2 is a perspective view showing in section the upper half of the magnetic tape cassette of FIG. 1 as it is cut through the transparent window along line I-I;

FIG. 3 is a partial section of the upper half shown in FIG. 2;

FIG. 4A is a partial enlarged sectional view showing how a wedge-shaped projection on the body of the upper half shown in FIG. 3 is in engagement with a wedge-shaped projection on the window member;

FIG. 4B is a partial enlarged sectional view showing a modification of the case shown in FIG. 4A;

FIG. 5 is a sectional view of the upper half of a magnetic tape cassette according to another example of the first embodiment of the fifth aspect of the invention;

FIG. 6A is an enlarged sectional view showing how a window frame on the body of the upper half shown in FIG. 5 is in engagement with a pawl member on the window member;

FIG. 6B is an enlarged sectional view showing a modification of the case shown in FIG. 6A;

FIG. 7 is a sectional view of the upper half of a magnetic tape cassette according to yet another example of the first embodiment of the fifth aspect of the invention;

FIG. 8 is a perspective view of the window member in the example shown in FIG. 7;

FIG. 9 is a partial enlarged perspective view of a window member engaging portion provided in the upper half of a magnetic tape cassette according to one example of the first aspect of the invention;

FIG. 10 is a perspective view of a window member having an engaging member that is engaged by the window member engaging portion of the upper half shown in FIG. 9;

FIG. 11 is a section of the window member and the window member engaging portion of the upper half as it is taken along the imaginary center line in FIG. 9;

FIGS. 12A, 12B and 12C are schematic views illustrating the process of fitting the window member according to the first aspect of the invention into the window member engaging portion of the upper half;

FIGS. 13A, 13B and 13C are schematic views illustrating the process of removing the window member according to the first aspect of the invention from the window member engaging portion of the upper half;

FIGS. 14A, 14B, 14C and 14D are perspective views showing four different shapes of the engaging member provided on lateral sides of the window member according to the first aspect of the invention;

FIG. 15 is a sectional view showing further details of the engaging grooves in the window member engaging portion of the example shown in FIG. 9;

FIGS. 16A and 16B are sectional views showing details of two additional examples of the engaging grooves in the window member engaging portion of the body of the upper half according to the first aspect of the invention;

FIG. 17 is a sectional view showing details of yet another example of the engaging grooves in the window member engaging portion of the body of the upper half according to the first aspect of the invention;

FIG. 18 is a sectional view of a transparent window portion of the upper half according to a first example of a second embodiment of the fifth aspect of the invention;

FIG. 19 is a section of the same transparent window except that it is taken through a plane perpendicular to the plane through which FIG. 18 was taken;

FIG. 20 is a perspective view showing details of a portion of the upper half into which the transparent window is to be fitted according to a second example of the second embodiment of the fifth aspect of the invention;

FIG. 21 is a perspective view showing diagrammatically an example of the magnetic tape cassette according to the sixth aspect of the invention;

FIG. 22 is section III-III of FIG. 21;

FIG. 23 is section IV-IV of FIG. 21;

FIG. 24 is a perspective view showing enlarged a part of a window receiving portion of the upper half of the magnetic tape cassette according to the same example;

FIG. 25 is a perspective view showing the window as it has been integrated into the upper half shown in FIG. 24;

FIG. 26 is a perspective view of the window used in the same example;

FIG. 27 is a perspective view of the magnetic tape cassette that is adapted for the method of fitting the window in the same example;

FIG. 28 is a perspective view showing a modification of the window that can be used in the same example;

FIG. 29 is a perspective view showing the upper half of a magnetic tape cassette having two transparent windows according an example of a third embodiment of the fifth aspect of the invention;

FIG. 30 is section V-V of FIG. 29 showing the upper half as it holds the transparent windows;

FIG. 31 is a side view of the window member shown in FIG. 30;

FIG. 32 is a perspective view of the window member as it is seen from the bottom;

FIGS. 33A and 33B are a perspective view and a side view, respectively, which show a transparent window in a magnetic tape cassette according to another example of the third embodiment of the fifth aspect of the invention;

FIG. 34 is a perspective view showing the opening in the upper half according to the example shown in FIG. 33;

FIG. 35 illustrates how the window member is in engagement with the inner peripheral surface of the opening according to the example shown in FIG. 33;

FIG. 36 is a perspective view showing a magnetic tape cassette having a separable transparent window according to an example of the second aspect of the invention;

FIG. 37 is a perspective view showing in section the upper half of the magnetic tape cassette shown in FIG. 36 as it is cut through the transparent window along line VI-VI;

FIG. 38 is section VII-VII of the upper half shown in FIG. 37;

FIG. 39 is section VII-VII of the window member of the transparent window shown in FIG. 37;

FIG. 40 is a sectional view of the window member shown in FIG. 39 as it is joined temporarily after having been inserted into grooves in the upper half;

FIG. 41 is a sectional view of the secure joint formed by ultrasonic or thermal welding of the temporary joint shown in FIG. 40;

FIG. 42 is a perspective view showing in section a transparent window in the upper half of a magnetic tape cassette according to another example of the second aspect of the invention;

FIG. 43 is a fragmentary perspective view showing the upper half of a magnetic tape cassette according to a first embodiment of the third aspect of the invention;

FIG. 44 is a sectional view of a transparent window in the upper half shown in FIG. 43;

FIGS. 45A and 45B are sectional views showing relative movements of molding dies intended to illustrate an example of the process for fabricating the transparent window in the upper half shown in FIG. 44;

FIG. 46 is a sectional view showing a window portion of the upper half in a magnetic tape cassette according to another embodiment of the third aspect of the invention and the die assembly for molding the window portion;

FIG. 47 is a plan view showing the upper half of a magnetic tape cassette according to an example of the fourth aspect of the invention and the residual tape check window provided in this upper half;

FIG. 48 is section VIII-VIII of FIG. 47 showing how the upper half is combined with the window;

FIG. 49 is a perspective view showing enlarged the upper half and window combination shown in FIG. 47;

FIG. 50 is a perspective view showing enlarged a part of the upper half according to the fourth aspect of the invention;

FIG. 51 is a perspective view showing enlarged a part of the window according to the fourth aspect of the invention;

FIG. 52 is an enlarged perspective view showing the window as it has been molded simultaneously with the upper half according to the fourth aspect of the invention;

FIGS. 53A and 53B are sections of a mold that correspond to section IX-IX of FIG. 52;

FIG. 53C is a perspective view of a moving core;

FIG. 54 is an enlarged perspective view of the window as it has been installed in the upper half according to the fourth aspect of the invention;

FIG. 55 is an enlarged perspective view showing, with part taken away, a manipulating engaging portion provided in the upper half of a magnetic tape cassette according to an example of the seventh aspect of the invention;

FIG. 56 is a longitudinal section of the upper half shown in FIG. 55;

FIG. 57 is a perspective view showing another example of the transparent window in the upper half according to the seventh aspect of the invention;

FIGS. 58A and 58B are sections of two examples of the engagement between the window and the upper half as they are cut through FIG. 57 along line XI-XI;

FIG. 59 is a perspective view showing diagrammatically a magnetic tape cassette according to an example of the ninth aspect of the invention;

FIG. 60 is an illustration of the breaking behavior of a common shaped resin article;

FIG. 61 is a perspective view showing an example of the window according to the ninth aspect of the invention;

FIG. 62 is a perspective view showing another example of the window according to the ninth aspect of the invention;

FIG. 63 is a perspective view showing yet another example of the window according to the ninth aspect of the invention;

FIG. 64 is a perspective view showing a still another example of the window according to the ninth aspect of the invention;

FIG. 65 is a perspective view showing diagrammatically a common magnetic tape cassette;

FIGS. 66A and 66B illustrate a conventional method for molding the upper half and the window of the magnetic tape cassette;

FIG. 67 is a perspective view of a prior art upper half, with it being cut across the transparent window; and

FIG. 68 is a section of FIG. 67 showing the upper half together with the transparent window.

On the following pages, the magnetic tape cassette of the present invention, the process for its manufacture, the shaped resin article, the method for multi-color molding of resin products and the method for destructing and separating parts made of dissimilar materials are described in detail with reference to the preferred examples shown in accompanying drawings.

First, we refer to FIGS. 1-8 and describe the magnetic tape cassettes according to the fifth aspect of the invention, particularly its first embodiment.

FIG. 1 is an exploded perspective view of a magnetic tape cassette with a transparent window according to a first example of the first embodiment of the fifth aspect of the invention. FIG. 2 is a perspective view showing in section the upper half of the magnetic tape cassette of FIG. 1 as it is cut through the transparent window along line I-I. FIG. 3 is a partial section of the upper half shown in FIG. 2. FIGS. 4A and 4B are partial enlarged sections showing two examples of the engagement between a first wedge-shaped projection on the body of the upper half (hereunder sometimes referred to as the base) and a second wedge-shaped projection on a window member.

The magnetic tape cassette with the transparent window according to the first example of the first embodiment of the fifth aspect of the invention is generally indicated by 10 in FIG. 1. As shown, a length of magnetic tape 12 is securely attached to a pair of take-up hubs 14, 14 at its ends and the remainder of tape length is wound around the respective take-up hubs 14, 14. The pair of take-up hubs 14, 14 around which the magnetic tape 12 has been wound is placed rotatably within a cassette case which is the combination of an upper half 16 and a lower half 18. The magnetic tape 12 is threaded in a specified path to be stretched between the two hubs such that only a portion 12a of the tape that is in a position which corresponds to the magnetic head on a record/reproduce apparatus (not shown) would otherwise be exposed to the outside.

In order to cover and protect the magnetic layer of the portion 12a of the magnetic tape which would otherwise become exposed to the outside of the cassette case, the upper half 16 is fitted with a front cover (lid) 22 that is axially supported by pins 20 and capable of pivoting between two positions, the CLOSE position where it covers the portion 12a of the magnetic tape and the OPEN position where it lets the portion 12a become exposed. The lid 22 is urged toward the CLOSE position by means of a torsion coil spring (not shown).

The lower half 18 has a rectangular bottom plate 24 which in turn has reel shaft insertion holes 26, 26 in the center; the reel shaft insertion holes 26, 26 rotatably support the pair of take-up hubs 14, 14 around which the magnetic tape 12 has been wound; in addition, when the magnetic tape cassette under consideration is loaded in a record/reproduce apparatus (not shown), the reel shafts (also not shown) on the apparatus pass through the holes 26, 26 into the take-up hubs, thereby driving them to rotate.

The bottom plate 24 has two forward extensions 28, 28 at the right and left ends. The extensions 28, 28 have cylindrical tape guides 30, 30 erected vertically on the bottom late 24; the magnetic tape 12 stretched between the take-up hubs 14, 14 is guided by means of the cylindrical tape guides 30, 30 such that it is threaded in a specified path to reach the front of the cassette case. The bottom plate 24 is cut out in the area between the two extensions 28, 28, leaving an opening in the cassette case.

Positioning pins (not shown) on the upper half 16 are inserted into the tape guides 30, 30 to achieve registration. The tape guides 30, 30 also serve as screw bosses through which screws (also not shown) are pushed from below into the threaded holes in the centers of the positioning pins and tightened to hold the upper half 16 and the lower half 18 together in secure position. Screw bosses 32, 32 having a similar structure to the tape guides 30, 30 are provided in the back at right and left corners of the lower half 18. By inserting screws into these four bosses and tightening them up, the cassette halves having the magnetic tape 12 and other components installed therein are securely held together to provide the magnetic tape cassette 10.

A slider generally indicated by 34 has a thin flat bottom plate 36 that is brought into contact with the underside of the bottom plate 24 of the lower half 18. When the cassette is not in service, the bottom plate 36 closes, for dust prevention, the open areas in the underside of the cassette case, namely, the opening in the lower half 18 and the reel shaft insertion holes 26, 26. Being guided by sidewalls 38, 38 of the lower half 18, the bottom plate 36 is capable of moving back and forth to slide along the underside of the lower half 18. If it moves forward, the bottom plate 36 closes the opening in the cassette case and the reel shaft insertion holes 26, 26; if it moves backward, the bottom plate 36 clears the opening in the cassette case and, at the same time, the reel shaft insertion holes 26, 26 in the lower half 18 come into registry with reel shaft insertion holes 40, 40 in the slider 34, making the cassette case ready for insertion of the aforementioned reel shafts on the record/reproduce apparatus.

The bottom plate 24 of the lower half 18 has a mid-wall 42 curved in arched form along the magnetic tape 12 wound around the take-up hubs 14. A leaf spring mount 44 is erected in front of a recess formed at the center junction of two arched halves of the mid-wall 42; a slider spring 46 in the form of a leaf spring is inserted between the recess at the center junction of the mid-wall 42 and the leaf spring mount 44 and it pushes ribs 48 at the front of the slider 34, whereby it is urged forward (in the direction of closing the slider 34).

A gear wheel 50 is provided in the center of each take-up hub 14. A braking member 52 provided on the upper half 16 has braking tabs 54 which engage the gear wheels 50, 50 to form an anti-rotation mechanism that prevents the take-up hubs 14, 14 from rotating when the magnetic tape cassette 10 is not in service. The upper half 16 has a transparent window through which the operator can visually check the amount by which the magnetic tape 12 has been wound onto the take-up hubs 14, 14. To make the transparent window, an opening is formed in the upper half's body 56 and a window member 58 made of a transparent resin (plastic material) is fitted in this opening.

FIG. 2 is a perspective view showing in section the upper half 16 of the magnetic tape cassette 10 as it is cut through the transparent window along line I-I in FIG. 1. As shown, the transparent window in the upper half 16 consists of an opening 56a formed in the body 56 of the upper half 16 as a window and a window member 58 that is made of a transparent resin and fitted in the opening 56a.

As shown in detail in FIGS. 3 and 4, the opening 56a formed in the upper half's body 56 has a first wedge-shaped projection 56b on th