Tape cassette

Abstract: A tape cassette suitable for digital recording and playback which require high reliability, since it has interchangeability in dimensions and shape with the conventional compact cassettes, is provided with the shutter member which selectively opens and closes the insertion window for the magnetic heads and pinch rollers, but is normally urged in the direction of closing, thereby to prevent dust, etc. from entering. Moreover, since the shutter member is arranged to slide in the direction of tape travelling, there is no increase in the volume of the tape cassette, even during opening or closing of the shutter member thus also contributing to size reduction of the compact cassette.

Description: BACKGROUND OF THE INVENTION The present invention generally relates to a magnetic tape and more particularly, to a tape cassette for storing therein a magnetic tape capable of recording and reproducing audio and/or video information such as music, video images, etc. Conventionally, as a tape cassette, there has been proposed a compact cassette, for example, as shown in Fig. 5, which is so arranged that a magnetic tape accommodated therein is exposed from a cassette shell housing 38, or cassette shells (referred to as a cassette shell housing hereinafter) through a magnetic head insertion window 34 and pinch roller insertion windows 35 formed at one side of the cassette shell housing 38 for inserting the magnetic heads and pinch roller means thereinto as disclosed, for example, in GB-A-1,052,249 (The compact tape cassette in Fig. 5 will be described in more detail later). Meanwhile, another conventional compact cassette 41 as shown in Fig. 16 includes a shield board 47 provided in front of magnetic heads 21 inserted in the insertion windows of the cassette shell housing 48. This shield board 47 protects the magnetic heads against electromagnetic waves emitted from mechanisms and external units. IN US-A- 4 620 254 defining the closest prior art from which the invention proceeds, there is disclosed a tape cassette having a sliding shutter member which shuts off the magnetic head insertion windows and pinch roller insertion window, etc. during non-use state of the tape cassette, and called, for example, a video tape cassette or digital audio tape cassette (referred as "DAT" hereinafter). A similar tape cassette is known from US-A- 4 618 903. In the conventional compact cassette as referred to above, however, since the magnetic tape is exposed from the insertion windows for inserting the magnetic heads in the cassette shell housing and insertion window for inserting the pinch-roller formed in the cassette shell housing, etc. dust entering through such insertion windows tends to adhere to the recording and reproducing surface of the magnetic tape, or an operator's hand may unintentionally or accidentally touch the recording and reproducing surface, thereby to damage it. Meanwhile, in the video tape cassette and DAT cassette or the like as referred to above, it is not possible for the dust or the like to enter inside, since the magnetic tape is protected by the shutter member when it is closed. But in the case where the tape cassette is to be mounted on a magnetic recording/reproducing apparatus for recording and reproducing, it is necessary to open the shutter member so as to pull out the magnetic tape, and dust or the like may also adhere to the recording and reproducing surface of the magnetic tape which is pulled out to be exposed. Another disadvantage is such that in the shielding structure of the above conventional compact cassette, there is provided no means for preventing the electromagnetic waves from the upper, lower, left, and right sides of the magnetic heads. In order to reduce the influence of the electromagnetic waves from the mechanisms as much as possible, another means to prevent electromagnetic waves inside the mechanism must be introduced. A further disadvantage of the above-mentioned known tape cassette is that, when opening the shutter member during the insertion of the tape cassette into a player, relatively high friction occures between the shutter member and the player due to camming engagement between shoulders of the shutter member and shoulders of the player. EP-A-0 406 943 and EP-A-0 434 134 being earlier European Patent Applications in accordance with Art. 54 (3) and (4) EPC each discloses a tape cassette which comprises a cassette shell housing which stores a recording medium in the form of a tape, and is formed with a plurality of insertion windows at its front face side, a shutter member having an U-shaped cross section for selectively opening and closing said insertion windows through sliding movement, and a shutter member comprising a pinch roller means insertion opening at a position corresponding to said insertion window for the pinch roller means and a recess provided adjacent to said pinch roller means inserting opening for said pinch roller means on one of two faces extending in a direction for inserting the magnetic heads of said shutter member which covers reel insertion holes being located at one side face of the housing, at open position of said shutter member. SUMMARY OF THE INVENTION Accordingly, an essential object of the present invention is to provide an improved tape cassette which has an interchangeability with conventional tape cassettes in dimensions and configuration and is suitable for digital recording/reproducing requiring a high reliability through prevention against entry of dust or the like, thereby to contribute to reduction in size of related applicances. Another object of the present invention is to provide a tape cassette of the above described type which has electro-magnetic shielding effects so as to protect magnetic heads against electro-magnetic waves directed from internal mechanisms and external appliances, etc. In order to achieve the above objects, in accordance with the present invention, a tape cassette comprises a cassette shell housing which stores a recording medium in the form of a tape, and is formed with a plurality of insertion windows at its front face side, a shutter member having an U-shaped cross section for selectively opening and closing said insertion windows through sliding movement, and is characterized in that a shield board is accommodated inside of one of said insertion windows for inserting magnetic heads into said cassette shell housing, the length of two faces of said shutter member extending in a direction for inserting the magnetic heads is set to be longer than a length from a face of said shutter member confronting the magnetic heads to said shield board provided inside of said insertion window for inserting said magnetic heads, and said shutter member is made of a shielding material and comprises a pinch roller means insertion opening at a position corresponding to said insertion window for the pinch roller means and a recess provided adjacent to said pinch roller means inserting opening for said pinch roller means on one of two faces extending in a direction for inserting the magnetic heads of said shutter member which covers reel insertion holes being located at one side face of the housing, at open position of said shutter member. An advantage of the present invention is that during operation, due to the provision of the shield board and the specifically defined extension of the two faces of the shutter member, there is provided an effective protection for the magnetic heads against electro-magnetic waves, and consequently the quality of recording and playback is significally increased. Furthermore, because of the pinch roller means insertion opening in the shutter member, there is an easy access for the pinch roller means to the tape during operation. Finally, a further advantage of the present invention is that, in the closed position of the shutter member, the reel insertion holes are covered by at least one of the two faces of the shutter member, and therefore dust is prevented from entering the inside of the tape cassette. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which; Fig. 1 is a perspective view of a tape cassette according to one preferred embodiment of the present invention as observed from above, Fig. 2 is a perspective view similar to Fig. 1, with a shutter member thereof opened through sliding, Fig. 3 is a bottom plan view of the tape cassette in Fig. 1, Fig. 4 is a perspective view of the shutter member of Fig. 1, as observed from above at its bottom portion, Fig. 5 is a view similar to Fig. 1, which particularly shows a conventional compact cassette (already referred to), Fig. 6 is a top plan view showing the tape cassette according to the one preferred embodiment of the present invention started to be loaded in a holder of a magnetic recording/reproducing apparatus, Fig. 7 is a fragmentary perspective view representing, on an enlarged scale, the holder and tape cassette shown in Fig. 6, Fig. 8 is a fragmentary side sectional view for explaining an essential portion in Fig. 6, Fig. 9 is a view similar to Fig. 6, which particularly shows the state where the tape cassette according to the one preferred embodiment of the present invention has been completed for mounting in the holder of the magnetic recording/reproducing apparatus, Fig. 10 is a top plan view showing the conventional compact tape cassette in Fig. 5 is started to be loaded in the holder of the magnetic recording/reproducing apparatus, Fig. 11 is a fragmentary side sectional view for explaining an essential portion in Fig. 10, Fig. 12 is a top plan view showing the state where the magnetic head and pinch roller are inserted into the insertion windows of the tape cassette (related to a second embodiment of the present invention), Fig. 13 is a fragmentary cross section, on an enlarged scale, taken along the line XIII-XIII in Fig. 12, Fig. 14 is a view similar to Fig. 12, which particularly relates to a third embodiment of the present invention, Fig. 15 is a fragmentary cross section, on an enlarged scale, taken along the line XV-XV in Fig. 14, and Fig. 16 is a top plan view showing another example of a conventional compact cassette (already referred to). DETAILED DESCRIPTION OF THE INVENTION Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. Referring now to the drawings, tape cassettes according to the present invention will be described hereinafter. In the first place, general construction of the conventional compact cassette commercially available at present, and also referred to earlier will be explained with reference to Fig. 5 before describing the tape cassettes of the present invention. In Fig. 5, the known compact tape cassette 31 includes the cassette shell housing 38 having a tape storing portion 37 for storing a magnetic tape 32, a pair of reel insertion holes 33 for receiving reel spindles to wind the magnetic tape 32, and a window portion 36 having a magnetic head insertion window 34 and pinch roller insertion windows 35, with a thickness A of the window portion 36 being set to be larger than a thickness B of the tape storing portion 37. According to the standards for compact cassettes, a distance C between the pair of reel insertion holes 33 is set to be 42.5mm and a distance D at the window portion 36, from a center or an intermediate point between the reel insertion holes 33, to one edge of the window portion 36 is 34mm. Referring particularly to Figs. 1 to 4, there is shown a tape cassette T1 according to one preferred embodiment of the present invention, which generally includes a cassette shell housing 8 having a tape storing portion 7 for storing a magnetic tape 2 therein, a pair of reel insertion holes 3 for receiving reel spindles (not shown) for winding the magnetic tape 2, and window portion 6 having almost the same thickness as said tape storing portion 7 and formed with an insertion window 4 for receiving a magnetic head means and insertion windows 5 for receiving a pinch roller means, a shutter member 9 with a U-shaped cross section for selectively opening and closing said insertion windows 4 and 5 through sliding movement, with the guides 10 provided on the shutter member 9 being slidably guided along guide grooves 11 formed in said cassette shell housing 8 in a direction connecting centers of said reel insertion holes 3 and normally urged in a direction for closing by an urging means 12, and a coupling portion 13 disposed adjacent to one side face of said shutter member 9 and provided at a front side of said cassette shell housing 8, with a center position at one edge of said coupling portion 13 in the tape travelling direction being set to be 34mm or more from an intermediate center position between the pair of the reel insertion holes 3 in the tape travelling direction. Here, the thickness E of the cassette shell housing 8 having the tape storing portion 7 and the window portion 6 is set to be equal to the thickness B of the tape storing portion 37 of the conventional compact cassette 31, referred to earlier with reference to Fig. 5. The distance F between the pair of reel insertion holes 3 is set to be the same as the distance C between the pair of reel insertion holes 33 of the conventional cassette 31 of Fig. 5. The distance G from the intermediate center position between the reel insertion holes 3, to the center position at one edge of the coupling portion 13 in the tape travelling direction is set to be 34mm, which is the same as the distance D in the known compact cassette 31 in Fig. 5. Referring also to Figs. 6 and 7, there is shown a holder 14 mounted on a holder base 15 so as to construct a holder portion TH of a magnetic recording/reproducing apparatus, which may detachably holds the conventional compact tape cassette 31 of Fig. 5 or the tape cassette T1 according to the present invention. In the holder portion TH referred to above, a detecting lever 16 which detects the window portion 36 of the compact cassette 31 is pivotally provided for movement around the holder 14 through a fulcrum of a projection 14a which is on the bottom of the holder 14. The forward end 16a of the lever 16 is bent into an approximately V-shape, and urges the detecting lever 16 by an urging means 17 so as to be brought into general contact with the tape storing portion 37 or 7 of the known compact cassette 31 or the tape cassette T1. A stopper 16b of the lever 16 contacts holder 14 to keep the detecting lever 16 in position. There is also pivotally provided in the holder portion TH, a turning lever 18 for rotation about a pivotal shaft 16c of the detecting lever 16. The lever 18 has a pin 18a on its distal end so as to open the shutter member 9 in association with the inserting operation of the tape cassette T1. Normally, the turning lever 18 is urged by an urging means 19 in the direction for ejecting the tape cassette T1. One end of the urging means 19 is engaged with a projection 16d of the detecting lever 16, while the other end is coupled with a projection 18b of the turning lever 18. The turning lever 18 is stopped at a specified position by a stopper 16e provided on the detecting lever 16. Shafts 15a are provided on opposite ends of the holder base 15, so as to be rotatable through bearings 20a provided on both ends of a base plate 20. Magnetic heads 21 and pinch rollers 22 are movably provided on the holder base 15. Functioning will be described hereinafter with respect to the case where the tape cassette according to the present invention is loaded in the holder portion having the construction as explained so far. In Fig. 6, 7 and 8, upon starting of insertion of the tape cassette T1, the pin 18a at the forward end of the turning lever 18 is guided to the coupling portion 13 which is close to the shutter member 9 of tape cassette T1. By further inserting the tape cassette T1, the turning lever 18 is rotated, and is urged in the ejecting direction by the urging means 19. Accordingly, the pin 18a is guided by the shape of the insertion windows 5 for the pinch rollers on the tape cassette T1, and causes the shutter member 9 to slide in the opening direction. When the loading of the tape cassette T1 has been finished as shown in Fig. 9, the shutter member 9 is in the open position so that magnetic heads 21 and pinch rollers 22 can be inserted. Fig. 10 shows the state where the conventional compact cassette 31 is started to be inserted in the holder portion TH for loading. Since the distance G from the intermediate center position between the reel insertion holes 3, to the position at the center of one edge of the coupling portion 13 of the cassette shell housing 8 for guiding the pin 18a at the forward end of the turning lever 18 to open the shutter member 9, is set to be 34mm or more in the tape travelling direction, the pin 18a at the forward end of the turning lever 18 is located in the vicinity (at the right side end in this example) without overlapping the window portion 36 of the compact cassette 31. Thus, as shown in Fig. 11, the forward end portion 16a of the detecting lever 16 which is near the turning lever 18 gets on the window portion 36 of the compact cassette 31, and the detecting lever 16 turns in the direction of an arrow F, thereby to turn the turning lever 18 so as to move the pin 18a to a non-operating position. It is a matter of course that the engaging length of the pin 18a with the tape cassette 31 is set shorter than the height of the window portion 36 of the compact cassette 31. As described above, the tape cassettes of the present embodiment has interchangeability in dimensions and shape with the conventional compact cassette 31. Therefore even when the conventional compact cassette is loaded on the magnetic recording/reproducing apparatus for loading the tape cassette of the present invention, it can be loaded without being obstructed by the shutter opening and closing mechanism. Referring also to Figs. 12 and 13, a tape cassette T2 according to a second embodiment of the present invention will be explained, also referring to Figs. 1 to 4 at portions showing a similar construction, with like parts being designated by like reference numerals. Similarly to the construction in Figs. 1,3 and 4, the tape cassette T2 of the second embodiment also includes the cassette shell housing 8 storing therein the magnetic tape 2 and having the pair of reel insertion holes 3 where the reel shafts are inserted to wind the magnetic tape 2 at one side of the cassette shells housing 8 . The distance F between the pair of reel insertion holes 3 is set to be the same as the distance C between the pair of reel insertion holes 33 of the conventional compact cassette 31 in Fig. 5 as referred to earlier. the cassette shell housing 8 has the insertion window 4 for the magnetic heads and the insertion windows 5 for the pinch roller means at the front side. These insertion windows 4 and 5 are virtually and generally at the same position and of the same dimensions as those in the conventional compact cassette 31. The shutter member 9 with the U-shaped cross section selectively opens and closes said insertion windows 4 and 5 through sliding movement, as it is slidably guided along the guide groove means 11 formed in said cassette shell housing 8 in the direction connecting centers of said reel insertion holes 3 and is normally urged in the direction for closing by the urging means 12 and the shutter member 9 has a pinch roller insertion opening 9a at the position corresponding to the insertion window 5 for the pinch roller 22, and a recess 9b which is adjacent to the pinch roller insertion opening 9a for the pinch roller 22 on one face 9c of two faces 9c and 9d extending in the direction for insertion of magnetic heads 21 of the shutter member 9 which covers reel insertion holes 3 at open position of the shutter member 9 (Fig. 4). Functioning of the tape cassette as described above will be explained hereinafter. In the tape cassette T2 according to the second embodiment, at the open position, when the shutter member 9 slides along guide groove means 11 and completely opens the insertion windows 4 and 5, the magnetic head 21 is inserted into the insertion window 4, and the pinch roller 22a, one of the pinch rollers 22, each rotatably mounted by a shaft 25 at the forward end of a lever 23 which is pivotally supported for pivotal movement about a pin 24, is inserted in the insertion window 5 as shown in Fig. 12. At this moment, the magnetic tape 2 is held between the pinch roller 22a and a capstan 26 and fed to the left. As illustrated in Fig. 13 showing a cross section taken along the line XIII-XIII in Fig. 12 on an enlarged scale, the pinch roller 22a made of rubber is mounted through a bearing 25a for rotation about the shaft 25. A width H of the pinch roller 22 should be about 1.5 times a width I of the magnetic tape 2. Meanwhile, since the upper portion of the pinch roller 22a inserted into the cassette shell housing 8 is covered by the face 9d of the shutter member 9 extending in the magnetic head inserting direction, the lever 23 of the pinch roller 22 has no room to form a shaft supporting portion, but, owing to the provision of a recess or notch 9b corresponding to the pinch roller 22 at the lower portion of the shutter member 9, the shaft 25 may be forced into and held by a shaft supporting portion 23a of the lever 23 corresponding thereto (Fig. 13). As described above, according to the tape cassette of the second embodiment, the slidable shutter member for selectively opening or closing the insertion windows of the cassette shell housing is arranged to cover the upper portion of the pinch roller inserted into the cassette shell housing at the open position, while said shutter member is formed with a recess at its lower portion so as to correspond to the pinch roller, and therefore, a pinch roller capable of maintaining a sufficient tape driving force may be freely designed, thus making it possible to prevent entry of dust and the like from above, not only at the closed position, but also at the open position of the shutter member when the tape cassette is loaded on a magnetic recording/reproducing apparatus. Referring further to Figs. 14 and 15, a tape cassette T3 according to a third embodiment of the present invention will be explained, also referring to Figs. 1 to 4 at portions showing a similar construction, with like parts being designated by like reference numerals. In Figs. 1,3,4 and 14, the cassette shell structure 8 accommodating the magnetic tape 2 therein has a shield board 27 made of steel, stainless steel or the like, and disposed at an inner side 4a of the insertion window 4 for the magnetic heads. The shutter member 9 having a U-shaped cross section and also made of a shield material such as steel or stainless steel is similarly arranged to selectively open or close the insertion windows 4 and 5, as the guides 10 of the shutter member 9 slide along the guide grooves 11 of the cassette shell housing 8. In Fig. 15, lengths J and K of two faces 9d an 9c from a front face 9e of the shutter member 9 extending in the direction of insertion of the magnetic head are each set to be at least longer than a length L from the front face 9e up to the shield board 27 provided at the inner side 4a of the magnetic head insertion window 4 of the cassette shell structure 8. In the tape cassette T3 of the third embodiment, the shutter member 9 is thus slid along the guide grooves 11, and allows the magnetic heads 21 to be inserted into the insertion window 4 of the cassette shell structure 8 at the open position. In the above state, the front, upper, lower, faces, and also right and left faces of the magnetic heads 21 inserted into the cassette shell structure 8 are covered by the shield materials of the shield board 27, two faces 9c and 9d extending in the magnetic head inserting direction of the shutter member 9, and the magnetic head confronting face 9e (Fig. 15). As is clear from the foregoing description, the tape cassette according to the present invention is suitable for digital recording and playback which require high reliability, since it has interchangeability in dimensions and shape with the conventional compact cassettes, is provided with the shutter member which selectively opens and closes the insertion windows for the magnetic heads and pinch rollers, but is normally urged in the direction of closing, thereby to prevent dust, etc. from entering. Moreover, since the shutter member is arranged to slide in the direction of tape travelling, there is no increase in the volume of the tape cassette even during opening or closing of the shutter member, thus also contributing to size reduction of the compact cassette. Furthermore, in the tape cassettes according to the present invention, since the front side of the magnetic head is covered with the shield board made of steel or stainless steel, and the upper, the lower, the right and the side faces of the magnetic head are surrounded by the shutter of steel or stainless steel which has a shield effect, the electro-magnetic waves from the mechanism and external appliances for the magnetic head can be prevented. Therefore, good recording and playback can be achieved.

Claims: A tape cassette which comprises: a cassette shell housing (8) which stores a recording medium in the form of a tape (2), and is formed with a plurality of insertion windows (4, 5) at its front face side, a shutter member (9) having an U-shaped cross section for selectively opening and closing said insertion windows (4, 5) through sliding movement, characterized in that a shield board (27) is accommodated inside of one of said insertion windows for inserting magnetic heads (21) into said cassette shell housing (8), the length (J, K) of two faces (9c, 9d) of said shutter member (9) extending in a direction for inserting the magnetic heads (21) is set to be longer than a length (L) from a face of said shutter member (9) confronting the magnetic heads (21) to said shield board (27) provided inside of said insertion window for inserting said magnetic heads (21), and said shutter member (9) is made of a shielding material and comprises a pinch roller means insertion opening (9a) at a position corresponding to said insertion window (4, 5) for the pinch roller means (22) and a recess (9b) provided adjacent to said pinch roller means inserting opening (9a) for said pinch roller means on one of two faces extending in a direction for inserting the magnetic heads (21) of said shutter member (9) which covers reel insertion holes (3) being located at one side face of the housing (8), at open position of said shutter member (9). Tape cassette as claimed in claim 1, characterized in that the shield board (27) is made of steel.

Inventors: FUJIKAWA AKINOBU, OHSHIMA MINEO, FUJIKAWA, AKINOBU, OHSHIMA, MINEO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1991
Main classification: G11B23
IPC codes: G11B23, G11B15