Tape cassette

Abstract: A tape cassette suitable for use in an 8-mm video tape recorder for recording and/or reproducing video and audio signals, which comprises a light projecting section inserting aperture (23) formed on the bottom surface of the cassette near the front surface of the cassette between supply and take-up reels (3a, 3b) juxtaposed in the cassette, light receiving windows (11a) formed through the both side walls of the cassette for passing therethrough a light emitted from a light emitting element inserted in the light projecting section inserting aperture (23) and a transparent portion (8) molded integrally with the upper surface of the cassette such that the supply and take-up reels are visible through the transparent portion, wherein a transparent portion (13) formed at least a part of a wall portion surrounding the light projecting section inserting aperture is integrally molded with the transparent portion of the upper surface of the cassette, to thereby easily manufacture the tape cassette which can prevent infiltration of dust or the like and accordingly protect the magnetic tape from appearing thereon rust or the like.

Description: This invention relates to a tape cassette suitable for use in an 8 mm-video tape recorder or the like for recording and/or reproducing audio and video signals. In a conventional reel-to-reel type tape cassette, tape end detection is provided by transparent leader and trailer tapes of the respective ends of the magnetic tape and secured to the supply and take-up reels. The leader and trailer tapes are detected optically by transmitted or reflected light. A tape cassette for use in recording and/or reproducing a video signal employing such transmissive light is disclosed in Official Gazette of Japanese Utility Model Registration Publication N. 55-40618. The tape cassette shown in this document has an opening through the bottom part at a position near the front surface of the cassette between the supply and take-up reels for receiving a light projecting section and light receiving windows formed through both the side walls of the cassette for transmitting therethrough the light from a light projecting element of the light projecting section when inserted in the opening. When the leader tape or the trailer tape is facing the light receiving windows, the light from the light emitting element is incident on a light receiving surface of a light receiving element disposed in the vicinity of the light receiving window, whereas the light from the light emitting element is interrupted by the magnetic tape when present. In the above mentioned tape cassette construction, if the magnetic tape is a metal tape, particularly a vapour deposited tape or the like which does not use a binder as a metal thin film is left preserved for a long time, dust and gas in the atmospheric air which may cause damage to the vapour deposited tape surface and so on can readily enter into the cassette through the light receiving windows formed through both the side walls and the light projecting section inserting opening, whereby not only can dust get on the magnetic tape surface but also rust may appear on the tape, particularly where it is one with a vapour-deposited surface. Naturally, the above mentioned conventional tape cassette is provided with a lid for closing the front opening portion of the cassette to protect the exposed tape and prevent dust from getting on the tape for preserving the cassette in no-use condition for a long time. This lid is designed to also close the light receiving windows formed through the both side walls. However, such construction cannot completely prevent rust from appearing on the tape. DE-A-3408694 discloses a cassette having a sleeve-shaped insert with windows therein for the passage therethrough of light. These windows are simple openings and are not glazed. Accordingly, air and dust can enter into the cassette, leading to tape damage. EP-A-163887 discloses a cassette whose light shaft is provided with windows glazed by a flexible piece of transparent film. Whilst this film can help to prevent the ingress of dust, this is reliant on the transparent film being cut to the correct size and shape and being correctly positioned within the cassette. Failure to control any one of these factors can lead to poor sealing of the light shaft windows. According to the present invention there is provided a tape cassette comprising: an upper cassette casing portion and a lower cassette casing portion, said two casing portions being secured together and containing therein tape wound around juxtaposed tape supply and take-up reels; wall means defining a passage extending into the cassette from an aperture provided in a bottom surface of the lower cassette casing portion, near to a front surface of the cassette and between the reels, said passage being provided for the insertion therein, in use, of a light emitting element and said wall means including first window means to pass light emitted by the light emitting element when, in use, the element is inserted in the passage; second window means provided in side walls of the cassette casing to pass light received from the first window means; and a transparent portion molded integrally with the upper cassette casing portion for the viewing therethrough of the reels; characterised in that: the first window means comprises transparent material molded integrally with said transparent portion, whereby the wall means closes the interior of the passage from the tape-containing interior of the cassette. The embodiment of tape cassette hereinafter described seals the cassette against the ingress of dust, gas and so on in atmospheric air. This helps to prevent rust from forming on the surface of the tape, as well as preventing drop-out on the magnetic tape and clogging of the magnetic head. An embodiment of tape cassette according to the present invention will hereinafter be described, by way of example only, with reference to the accompanying drawings in which:- Fig. 1 is a perspective view showing the appearance of an embodiment of a tape cassette according to the present invention; Fig. 2 is an exploded perspective view of a main portion of the tape cassette of Fig. 1; and Fig. 3 is a perspective view of the upper half of the tape cassette of Fig. 1. In Fig. 1, a tape cassette, specifically a tape cassette for use in the so-called 8mm video tape recorder in the present embodiment, is generally indicated at 1. A cassette housing 2 is formed of upper and lower halves 2a and 2b made of opaque resin material, for example ABS resin, which are secured together. A pair of reel hubs 3a and 3b are accommodated in the upper and lower halves 2a and 2b of the cassette housing 2, on which a magnetic tape 4 is wound. Reel urging springs 5a and 5b urge the reel hubs 3a and 3b, respectively, so as to prevent the reel hubs 3a and 3b from being vibrated. The magnetic tape 4 wound about the reel hubs 3a and 3b is exposed through a tape guide at the front surface portion of the cassette housing 2 and is provided at its ends with leader and trailer end-detection portions. The tape exposing portion at the front surface is normally closed by a front surface lid 6 which is rotatably pivoted on the front surface of the cassette housing 2. When the cassette is in use, the front surface lid 6 is rotated in the opening direction to expose the magnetic tape 4 at the front surface portion of the cassette housing 2. A label area 7 is formed on an approximately central portion of the upper surface of the upper half 2a which is slightly recessed from the reference surface on the upper surface of the upper half 2a for adhering thereon a label on which the recorded contents of the tape can be written or printed. Adjacent to the label area 7, there is formed a window portion 8 in a rear portion of the upper surface of the upper half 2a such that substantially all portion of the magnetic tape 4 wound around the reel hubs 3a and 3b is visible therethrough. There are arranged in the cassette housing 2 members used for detecting the tape ends, bases for mounting the reel urging springs 5a and 5b, reel brake members and so on, as will be later referred to, which, however, are all covered with the main body portion of the upper half 2a made of opaque material, so that they are not visible from the outside. The window portion 8 is formed in the tape cassette constructed as described above in the following manner. Transparent material 9 such as acrylic resin or the like is laminated on the main body portion of the upper half 2a by lamination two-colour molding technique using, for example, a rotary core to form a two-layer laminated portion 10 which is located at the rear side portion of the upper surface of the upper half 2a. This laminated portion 10 has a portion thereof formed of only the transparent material 9 which constitutes the window portion 8. The window portions 8 are each formed in a circular shape having substantially the same diameter as a maximal diameter of the magnetic tape 4 wound around the reel hubs 3a and 3b. The magnetic tape 4 loaded in the tape cassette 1 has leader and trailer tapes at its respective ends, as noted above. For detecting these leader and trailer tapes, the cassette housing 2 is provided with a light projecting section inserting aperture 23 is arranged at the centre near the front surface of the cassette on the bottom of the lower half 2b, and the light receiving windows 11a are formed respectively through left and right end portions of a side wall 11 surrounding the outer periphery of the upper half 2a as shown in Fig 3. In the present embodiment, substantially annular wall portions 12 and 22 are integrally formed on the upper and lower halves 2a and 2b at positions surrounding the light projecting section inserting aperture 23, as shown in Fig 2. The annular wall portion 12 on the upper half 2a has two transparent portions 13 made of the transparent material 9 at two positions, i.e. the left side face and the right side face of the cassette, whereas the rest of the annular wall portion 12 is made of opaque resin material. The respective transparent portions 13 are integrated, through coupling protrusions 14, with the window portions 8 made of the transparent material 9 formed on the upper surface of the upper half 2a. Thus, the transparent portions 13 are integrated with the window portions 8 when the latter are molded. In the present embodiment, the lower end portions 13a of the transparent portions 13 near the lower half 2b protrude downwardly further than the opaque portion of the wall portion 12. The upper half 2a is provided with a guiding rod 16 protruding adjacent to the wall portion 12 of the upper half 2a for aligning the upper and lower halves 2a and 2b when they are secured with each other. Further, reinforcing ribs 15 are formed on the inner surface of the upper half 2a at the boundary between the window portion 8 and the opaque portion near the front surface portion. The wall portion 22 provided around the light projecting section inserting aperture 23 on the lower half 2b is molded adjacent a side wall 21 surrounding the outer periphery of the lower half 2b. A cut-away concave portion 22a is provided in the wall portion 22 at two positions corresponding to the lower end portions 13a of the transparent portions 13 of the upper half 2a. A guide rod accommodating portion 24 is provided at the position corresponding to the guide rod 16 integrally with the wall portion 22. The guide rod accommodating portion 24 has a guide rod inserting hole 24a at the centre thereof. When the upper half 2a and the lower half 2b are coupled together, insertion of the guide rod 16 into the guide rod inserting hole 24a makes the side wall 11 of the upper half 2a and side wall 21 of the lower half 2b come into contact with each other, whereby a spacing for accommodating the magnetic tape 4 is formed inside. In this event, the lower ends 13a of the transparent portions 13 of the wall portion 12 of the upper half 2a are engaged with the cut-away concave portions 22a of the wall portion 22 of the lower half 2b, and consequently the wall portions 12 and 22 of the upper and lower halves 2a and 2b are abutted and coupled together. Therefore, the inside spacing of the light projecting section inserting aperture 23 is separated by the wall portions 12 and 22 from the magnetic tape accommodating spacing in the cassette housing 2. Next, explanation will be given of how the beginning end and the terminating end of the tape 4 are detected when the tape cassette 1 of the present embodiment is loaded in the video tape recorder. As illustrated in Fig 3, a light emitting element L disposed in the video tape recorder is inserted into the light projecting section inserting aperture 23 on the bottom surface of the tape cassette 1, and light receiving elements (not shown) are positioned in the vicinity of light receiving windows 11a on the left side end and the right side end of the tape cassette 1, respectively. Thus, a light ℓ from the light emitting element L is emitted through the transparent portions 13 of the wall portion 12 to the magnetic tape 4 accommodated in the cassette. When the transparent leader tape or the transparent trailer tape of the magnetic tape 4 is transported in front of the light receiving windows 11a, the light ℓ passes through the transparent tape and reaches the light receiving window 11a, whereby the light receiving element disposed in the vicinity of the light receiving window 11a detects the light ℓ which has passed through the tape and accordingly the beginning or terminating end of the tape can be detected. The tape cassette of the present embodiment is provided with the transparent portions 13 in the wall portion 12 of the aperture 23 for inserting the light projecting section for detecting the beginning and terminating ends of the tape, and the inside of the inserting aperture 23 is separated from the tape accommodating space in the cassette housing 2, so that the inside of the cassette housing 2 can be highly sealed. It is therefore possible to prevent infiltration of dust and so on into the cassette housing 2 and degradation of the magnetic tape by appearance of rust thereon or the like and avoid occurrence of the aforementioned drop-out. Further, since the transparent portion 13 of the wall portion 12 surrounding the light projecting section inserting aperture 23 is molded integrally with the window portion 8 of the upper surface of the upper half 2a integrated with the opaque portion by the lamination two-colour molding, it is resin-molded simultaneously with the window portion 8. Such construction of the present embodiment can reduce the number of components and simplify the tape cassette, compared with a cassette in which the transparent portion 13 is assembled as a separate part. The transparent portion 13 is coupled with the window portion 8 through the coupling protrusions 14, so that resin can be implanted up to the transparent portion 13 from the gate for molding the window portion 8 upon resin-molding. Therefore, only one gate for implanting transparent resin is sufficient so that the molding machine for the tape cassette of the present embodiment can be simplified. According to the tape cassette of the present invention as described above, since the inside of the light projecting section inserting aperture is sealed with the wall portion having the transparent portion, infiltration of dust or the like is prevented. Further, since the transparent portion is molded integrally with the transparent portion of the upper surface of the cassette, the tape cassette of the present invention can be easily manufactured.

Claims: A tape cassette comprising: an upper cassette casing portion (2a) and a lower cassette casing portion (2b), said two casing portions being secured together and containing therein tape (4) wound around juxtaposed tape supply and take-up reels (3a, 3b); wall means (12, 13, 22) defining a passage extending into the cassette from an aperture (23) provided in a bottom surface of the lower cassette casing portion (2b), near to a front surface of the cassette and between the reels (3a, 3b), said passage being provided for the insertion therein, in use, of a light emitting element and said wall means including first window means (13) to pass light emitted by the light emitting element when, in use, the element is inserted in the passage; second window means (11a, 11b) provided in side walls (11) of the cassette casing to pass light received from the first window means (13); and a transparent portion (8) molded integrally with the upper cassette casing portion (2a) for the viewing therethrough of the reels (3a, 3b); characterised in that: the first window means (13) comprises transparent material molded integrally with said transparent portion (8), whereby the wall means (12, 13, 22) closes the interior of the passage from the tape-containing interior of the cassette. A tape cassette as claimed in claim 1, wherein said first window means (13) of the wall means (12, 13, 22) is coupled with said transparent portion (8) through coupling protrusions. A tape cassette as claimed in claim 2, wherein said transparent portion (8) has a gate for molding, so that resin can be implanted up to said transparent material of the first window means (13).

Inventors: IWAHASHI YUGI C O SONY MAGNETI, IWAHASHI, YUGI C/O SONY MAGNETIC PRODUCTS INC.
Applicants: SONY CORP, SONY CORPORATION
Application year: 1988
Main classification: G11B23
IPC codes: G11B23