Tape cassette with reduced wear of positioning holes
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to audio and visual equipment, and more particularly to tape cassettes for such equipment, which have recording tapes installed therein. 
     2. Description of the Prior Art 
     In current audio and visual equipment, tape cassettes have been widely used for the ease with which they can be handled. They are usually constructed of plastics and have a recording tape installed therein. 
     In order to clarify the purpose of the present invention, a conventional video tape cassette 1 will be described briefly with reference to FIG. 4 of the accompanying drawing. 
     In the drawing, the numeral 2 denotes a lower shell of the video tape cassette 1. Denoted by numeral 3 is a pivotal front lid of the tape cassette 1. The lower shell 2 is provided at its front side near the front lid 3 with a first pair of positioning openings 1A and 1A and at its rear side with second pair of positioning openings 1B and 1B. When the tape cassette 1 is put into a video tape cassette player, metal positioning pins of the player are inserted into the corresponding positioning openings 1A, 1A, 1B and 1B to achieve positioning of the tape cassette 1 relative to the player. 
     However, hitherto, the durability of the positioning openings 1A, 1A, 1B and 1B, more specifically, the durability of the lower shell 2 at the portions which define the openings 1A, 1A, 1B and 1B has been given little thought. In fact, after long use of the tape cassette, the opening defining portions of the lower cassette 2 have shown marked wear due to repeated sliding engagement between the positioning openings 1A, 1A, 1B and 1B and the corresponding positioning pins of the player. In such case, accurate positioning of the worn tape cassette 1 relative to the player is almost impossible. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a tape cassette which is free of the above-mentioned drawback. 
     According to the present invention, there is provided a tape cassette whose positioning openings are constructed to bear up against the repeated sliding engagement with the positioning metal pins of the player. 
     According to the present invention, there is provided a tape cassette in which each of the positioning openings of the tape cassette is reinforced by a wear-resistant bearing member inserted therein. 
     According to a first aspect of the present invention, there is provided a tape cassette which comprises a cassette proper for containing therein a recording tape; means for defining at least one positioning opening in the cassette proper; and a wear-resistant bearing member fitted in the positioning opening to reinforce the same. 
     According to a second aspect of the present invention, there is provided a tape cassette which comprises a cassette proper for containing therein a recording tape, the cassette proper being constructed of a plastic; means for defining at least one collared positioning opening in the cassette proper; and an annular bearing member fitted in the positioning opening to reinforce the same, the annular bearing member being constructed of a material having higher wear resistance and less sliding friction than the plastic material forming the cassette proper. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is an enlarged sectional view of an essential portion of a tape cassette according to an embodiment of the present invention, showing an annular bearing member fitted in an opening of a lower shell; 
     FIG. 2 is a view similar to FIG. 1, but showing a condition wherein the annular bearing member is separated from the lower shell; 
     FIG. 3 is a perspective view of the annular bearing member; and 
     FIG. 4 is a bottom view of a conventional tape cassette. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring particularly to FIGS. 1 and 2, it will be noted that a tape cassette according to an embodiment of the present invention includes a lower shell 2 to which an upper shell (not shown) is fixed to constitute a tape chamber therebetween. The lower and upper shells are constructed of plastic, such as, acrylonitrile-butadiene-styrene, polystyrene or the like. As is understood from FIG. 2, the lower shell 2 is formed with openings 5 each formed with an upstanding collar 6 extending therearound and only one of which is shown. Each opening 5 is formed with an enlarged or counter-bored bottom portion 5a, as shown. 
     An annular bearing member 4 is fitted in each collared opening 5 to define a reinforced positioning opening 1A. The annular bearing member 4 is constructed of a material, such as polyoxymethylene or the like, having a relatively high wear resistance and a relatively low co-efficient of sliding friction. If desired, a metallic bearing member may be used. More specifically, the annular bearing member 4 is constructed of a material whose wear resistance is higher than that of the material of the lower shell 2, and whose sliding friction relative to the metal positioning pin is less than that of the material of the lower shell 2. 
     As is seen from FIGS. 2 and 3, the annular bearing member 4 is formed with a head portion 4A of arrow-shaped cross-section and an annular outwardly directed base flange 4B. The leading or upper end portion of the annular bearing member 4 is formed, at its diametrically opposed portions, with rectangular cuts 4C opening upwardly through the head portion 4A. As is seen from FIG. 1, the base flange 4B is dimensioned so as to match or fit closely within the enlarged bottom portion 5a of the collared opening 5 of the lower shell 2. 
     In coupling together each bearing 4 with the cassette shell 2, the annular bearing 4 is inserted upwardly into the collared opening 5 from the underside of the lower shell 2. This insertion is made prior to the fixing of the upper shell to the lower shell 2. Due to provision of the diametrically opposed cuts 4C, during the insertion of the bearing 4 into the collared opening 5, the arrow-shaped head portion 4A is resiliently deformed inward. When the annular bearing member 4 is brought to a terminal position in the opening 5, the resiliently deformed arrow-shaped head portion 4A expands radially outward thereby to engage with the upper end edge of the collar 6 extending around. opening 5, and at the same time, the base flange 4B of the annular bearing member 4 is intimately fitted in the enlarged bottom portion 5a of the collared opening 5, as is seen from FIG. 1. Upon the occurrence of the foregoing, the annular bearing member 4 is latched to the collared opening 5. 
     As is understood from the foregoing description, in accordance with the present invention, the positioning opening of the tape cassette is reinforced by a bearing member 4 which is constructed of material of high wear resistance relatively small and less sliding friction, such as polyoxymethylene, metal or the like. Accordingly, undesired marked wear of the positioning opening of the tape cassette does not occur, and thus, accurate positioning of the tape cassette relative to the player is assured for a long time. 
     Possible modifications of the above will now be described. 
     If desired, the annular bearing member 4 may be installed in the lower shell 2 by means of the integral molding technique. In that case, the annular bearing member 4 is handled as an insert. 
     If desired, the annular bearing members 4 may be applied to only selected ones of the openings 5 of the lower shell 2.