Cassette loading and unloading mechanism and cassette for use in the same

Abstract: Disclosed is a cassette loading mechanism capable of loading each of cassettes having different dimensions and cassettes to be used therefor. The mechanism comprises a cassette insertion slot, a cassette loading slider, a projecting guide rail for positioning each cassette, a depressed positioning groove formed in each cassette, and a cassette detecting member. Even cassettes having different heights can be each used as it is, and cassettes having different lengths and widths can be each used in an identical VTR.

Description: The present invention relates to an audio and video device using a magnetic tape cassette, and more particularly to a cassette transport mechanism for loading and unloading a magnetic tape cassette. There has been known a cassette loading system capable of loading each of different types of cassettes into a VTR (Video Tape Recorder). Such a conventional cassette transport mechanism is disclosed, for example, in the Japanese Patent Application Laid-Open Publication No. Sho-64-42051. Fig. 1 shows an example of a conventional cassette transport mechanism capable of loading and unloading two types of cassettes having an identical height T and different widths L and depths W. Figs. 2 and 3 show conventional cassettes for use in the conventional cassette transport mechanism shown in Fig. 1, where Fig. 2 shows the cassette 10f for regular use and Fig. 3 shows the cassette 10g for long-play use. When either type of the cassettes 10f and 10g is inserted into the cassette transport mechanism, it is discriminated whether the inserted cassette is a regular type 10f or a long-play type 10g. Then a reel base for receiving the reels of the cassette in the VTR is moved in such a manner that the reel interval of the reel base corresponds to the distance between the two reels of the inserted cassette thereby to enable subjecting each of the two types of cassettes to recording and playback in an identical VTR. In order to subject each of the two types of the cassettes 10f and 10g to recording or playback, it is necessary to make constant the relationship of the relative position between each of the two types of the cassettes and the cassette transport mechanism. For the above-mentioned purpose, a guide groove 14 is formed in the exterior bottom of each of the cassettes as shown in Figs. 2 and 3. On the other hand, a guide rail 15 is provided at the bottom of the cassette insertion portion in the cassette transport mechanism in such a projected form that the guide rail is fit in the cassette guide groove 14 of the inserted cassette as shown in Fig. 1, so that the guide groove 14 is to be engaged with the guide rail 15 to enable inserting either the cassette 10f or the cassette 10g in a prescribed position in the cassette transport mechanism. The above-mentioned VTR is used in a broadcasting station or a similar place. Meanwhile, in a VTR for home use, only one cassette type is used, and therefore no guide groove 14 is provided in the home-use cassette. Henceforth, the amount of data to be recorded will significantly increase according as the video technology develops. As a consequence of recording more data, tape consumption amount will of course increase. Therefore, the cassette size is required to be increased, and a plurality of cassette types having different lengths and widths will be produced to cope with different recording time. It is also anticipated that a cassette having a different height will be produced for the purpose of increasing the rigidity and improving the dustproof capability of a cassette half while keeping the same tape width. In order to subject each of such cassettes having different dimensions in size to recording and playback in the same VTR, it has been necessary to provide the guide or positioning groove described above in the conventional example in every cassette. EP 0 286 751 describes a cassette loading and unloading mechanism according to the precharacterizing part of claim 1. This mechanism allows the insertion of two different cassette types, a first large-sized tape cassette, or a second small-sized tape cassette for recording and/or reproducing. The large cassette has a bottom surface with two grooves therein spaced from each other by a distance equal to the width of the small cassette. The apparatus includes a cassette holder having a pair of parallel guide rails spaced apart for slidable reception in the grooves of the large cassette, or for slidable engagement of confronting surfaces of the guide rails within the surfaces of the small cassette. A mechanism may be provided for responding to the size of the cassette inserted into the holder for suitably positioning the reel tables for engagement with the reels of the cassette. An essential objective of the present invention is to provide a cassette transport mechanism capable of loading and unloading either cassettes with a greater width and having guide grooves or cassettes with a smaller width having no guide groove with the additional capability to load and unload such cassettes also having varying height. The cassette loading and unloading mechanism of the invention is defined by claim 1. A small type cassette is to be inserted between the above-mentioned projecting portions provided on the cassette tray apart by a distance approximately equal to the width of the cassette to enable positioning the small type cassette with the side surfaces of the cassette checked by the projecting portions. With regard to a large type cassette, a pair of guide grooves are provided in the exterior bottom of the cassette to make the guide grooves serve as positioning grooves. Since the insertion positions of small type cassettes having different widths and heights are not absolutely fixed, the insertion position of each cassette is detected by detector means to judge whether the cassette is really inserted in the correct position. BRIEF DESCRIPTION OF THE DRAWINGS In the following preferred embodiment of the invention are described with reference to the accompanying drawings, in which: Fig. 1 is a front view of a conventional cassette insertion slot; Figs. 2 (a) and 2 (b) are schematic views of a regular cassette; Figs. 3 (a) and 3 (b) are schematic views of a long-play cassette; Figs. 4 (a) and 4 (b) are schematic views of a regular cassette having no guide groove; Figs. 5 (a) and 5 (b) are schematic views of a long-play cassette having guide grooves; Fig. 6 is a side view of a cassette transport mechanism; Fig. 7 is a schematic view of a cassette insertion slot of the cassette transport mechanism ; Fig. 8 is a perspective view of a guide rail of a cassette loading mechanism; Fig. 9 is a perspective view of a guide rail of a cassette loading mechanism; Figs. 10 (a) and 10 (b) are schematic views of guide grooves of a cassette; Fig. 11 is a schematic view of a linear skating type embodiment; Fig. 12 is a perspective view of a guide rail of a linear skating type cassette loading mechanism; Fig. 13 is a perspective view of a cassette which cannot be inserted upside down into the slot; Figs. 14 (a) and 14 (b) are schematic views of a regular cassette having a greater height; Figs. 15 (a) and 15 (b) are schematic views of a long-play cassette having a greater height; Fig. 16 is an explanatory view of a cassette loading mechanism in accordance with the present invention; and Fig. 17 is an explanatory view of a cassette loading mechanism in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Firstly described as follows is a cassette loading mechanism capable of loading either a cassette having no guide groove or a cassette having a pair of guide grooves formed in the exterior bottom of the cassette. Figs. 4 (a) and 4 (b) show a regular type cassette 10a having its length L, depth W, and height T which is provided with no guide groove in the exterior bottom thereof. Figs. 5 (a) and 5 (b) show a long-play cassette 10b having its width L' greater than the width L, its depth W' greater than the depth W, and its height T identical to that of the regular type cassette 10a. The long-play cassette 10b is provided with a pair of guide grooves in the depthwise direction apart by a distance L in the exterior bottom of the cassette. Referring to Fig. 6, which shows a cassette loading and unloading mechanism of a VTR, a guide plate 1 having two L-shaped grooves 2a and 2b formed therein is fixed to a main chassis 3 of the VTR by means of setscrews 4a and 4b. A drive gear 5 with a drive arm 6 fixedly connected is so mounted to the guide plate 1 as to be coaxially rotatable. A cassette tray 7 is provided with guide pins 8a and 8b which are respectively interposed in the L-shaped grooves 2a and 2b of the guide plate 1, and the guide pin 8b is further interposed in a U-shaped groove 9 defined by the drive arm 6. In Fig. 6, when a cassette 10 is manually inserted into the VTR and loaded on the cassette tray 7, the cassette 10 is securely pressed against the cassette tray 7 by a cassette spring 11 (the member for fixing the spring 11 being not shown) which is attached to the cassette tray 7. The cassette 10 securely loaded on the cassette tray 7 is detected by a cassette loading switch (not shown) and then a drive motor (not shown) is driven to rotate the drive gear 5 together with the drive arm 6 attached thereto in the direction indicated by an arrow A in Fig. 6. With the rotation of the drive arm 6, the guide pin 8b is driven to move the cassette tray 7 horizontally and both the guide pins 8a and 8b of the cassette tray 7 are guided along the two L-shaped guide grooves 2a and 2b of the guide plate 1 and then the cassette tray 7 is moved downward to a position 7p for recording and playback to complete the operation of loading the cassette 10 into the VTR deck. When unloading the cassette 10 from the VTR, the drive motor (not shown) is reversely rotated to reverse the above-mentioned motions to remove the cassette 10. Fig. 7 shows a cassette insertion slot of the cassette transport means when viewed in the direction as indicated by the arrow B in Fig. 6. Referring to Fig. 7, a pair of projecting portions (referred to as "guide rails" hereinafter) 15 for positioning a cassette are provided apart by a distance L on the cassette tray 7. When inserting the regular type cassette 10a having no guide groove as shown in Figs. 4 (a) and 4 (b) into the cassette insertion slot, since the width of the cassette 10a coincides with the interval L between the guide rails 15 on the cassette tray 7, the cassette 10a can be regularly inserted between the guide rails 15 to be positioned with accuracy. When inserting the long-play cassette 10b as shown in Figs. 5 (a) and 5 (b) into the cassette insertion slot of the VTR, the cassette 10b can be positioned by aligning the guide rails 15 of the cassette tray 7 to be engaged with the guide grooves 14 apart by a distance L of the cassette 10b. Although not shown, a cassette having a greater width than that of the cassette 10b can be also inserted in the prescribed position by forming guide grooves 14 apart by a distance L in the exterior bottom of the cassette. By providing the guide rails 15 at the right and left positions on the cassette tray 7, any cassette can be inserted stably. The following describes the configuration of the guide rails 15. Fig. 8 shows a perspective view of a slot-in type cassette tray 7 where the cassette receiving ends of the guide rails 15 are narrowed, in other words, the interval between the guide rails 15 at the cassette receiving portion are spread to facilitate inserting the regular type cassette 10a into the VTR. Fig. 9 shows exemplified guide rails 15 of which cassette receiving ends are chamfered to facilitate inserting the cassette 10a. The chamfering may be also replaced by rounding to produce the same effect. Fig. 10 (b) shows a bottom view of a cassette having guide grooves 14. By partially spreading the widths of the guide grooves 14 at the leading ends for insertion, the guide rails 15 of the cassette tray 7 do not impede the entrance of the guide grooves 14 of a cassette even when the cassette insertion position slightly deviates to thereby enable easy insertion of the cassette. Fig. 11 shows a linear skating type cassette tray 7 in contrast to the slot-in type shown in Fig. 1. Fig. 12 shows a perspective view of the linear skating type cassette tray 7 which vertically receives a cassette, and therefore the upper surfaces of the guide rails 15 are each chamfered to facilitate fitting the cassette 10a or 10b on the cassette tray 7. It is noted that the guide rails 15 may be rounded instead of being chamfered to produce the same effect. Fig. 13 shows a cassette having no guide grooves 14, where the width of the cassette is made greater by 2δ than the interval L between the guide rails 15 except the lower portion of the cassette which is to be guided by the guide rails 15 has a width L thereby to prevent the cassette from being reversely inserted upside down. Each cut-off portion of δ has a height γ greater than the height of each of the guide rails 15 (the length 26 distributed to both sides of the cassette in Fig. 13 may be alternatively provided on one side of the cassette). The following describes the case where cassettes having different heights are compatibly used in one cassette transport mechanism. Figs. 14 (a) and 14 (b) show a cassette 10c having a width L, a depth W, and a height T + A, which is not provided with any guide groove in the exterior bottom of the cassette 10c. Fig. 15 shows a cassette 10d having its width L' greater than L, depth W' greater than W, and height T + A which is provided with guide grooves 14 apart by distance L in the exterior bottom of the cassette 10d. Fig. 16 shows the cassette insertion slot of a cassette transport means of the present invention in the same manner as in Fig. 7. In Fig. 16, a cassette transport mechanism receives each of the cassettes 10a and 10b having their height T as shown in Figs. 4 and 5 as well as the cassettes 10c and 10d having the height T + A as shown in Figs. 14 and 15. Referring to Fig. 16, the height of a cassette insertion slot 12 is approximately T + A, the height of each of the guide rails 15 is approximately A, and the interval between the guide rails is L. Therefore, the regular cassette 10c having a great height T+A and no guide groove as well as the long-play cassette 10d having a great height T+A and guide grooves 14 can be each inserted practically only into the predetermined position in the cassette insertion slot 12. When inserting the cassette 10a or 10b having the height T, each of the cassettes 10a and 10b cannot have a fixed insertion position since the cassette insertion slot 12 has a height greater by the dimension A than the height of each of the cassettes. However, by giving each of the guide rails a height of approximately A, the gap in height between the guide rails 15 and the cassette insertion slot 12 is made equal to the cassette height T at a narrow portion. Therefore, the cassette 10a is naturally inserted into the wide space between the guide rails 15. The cassette 10b can be also inserted most easily into the cassette insertion slot 12 when the guide grooves 14 are aligned with the guide rails 15, in which condition the clearance between the cassette 10b and the cassette insertion slot 12 is greatest. If the height of each of the guide rails was smaller than the difference A in height between the cassette insertion slot and the cassette, each of the cassettes 10a and 10b could be inserted into any space in the cassette insertion slot 12, which means that these cassettes might not be set in the correct position. Therefore, the cassette position is detected by means of cassette detectors 16a, 16b, and 16c provided on the upper inner wall of the cassette insertion slot as shown in Fig. 17. The detectors 16a and 16c oppose the right and left guide rails 15 respectively and the detector 16b is interposed between the detectors 16a and 16c. The detection signals obtained from the detectors are discriminated by a discriminator 17. When the cassette position is correct, the cassette is to be loaded into the VTR. When the cassette position is not correct, a signal indicating that the cassette position is not correct is generated by the discriminator 17. The above-mentioned cassette insertion actions are described as follows with regard to the low-height cassettes 10a or 10b. When the cassette 10a or 10b is inserted into the correct position, the detectors 16a, 16b, and 16c are all turned off. When the insertion positions of the cassettes 10a and 10b are incorrect, the detector 16a or 16c is turned on to detect that the cassette is inserted in an incorrect position. As described above, either the cassette having a guide groove or the cassette having no guide groove can be used in an identical VTR, and furthermore a cassette having a different height can be used. It is important to assure compatibility between a new system and the conventional system. In the above regard, the present invention is capable of using conventional cassettes to enable effective use of all such cassettes.

Claims: A magnetic tape cassette loading and unloading system capable of loading and unloading each of a first type tape cassette (10a) having a width L and a height T, which is not provided with a groove and a second type tape cassette (10b) having a width L' greater than L, which is provided with a pair of grooves (14) formed in the exterior bottom of the cassette, said mechanism comprising: cassette transport means for transporting an inserted cassette from a first position for loading the cassette to a second position for subjecting the cassette to a recording or playback operation, said cassette transport means comprising a cassette insertion slot (12) and a cassette tray (7) which is provided with a pair of guide rails (15) formed thereon in the depthwise direction corresponding to the cassette inserting direction for guiding each inserted cassette, said projecting portions (15) being apart widthwise by a distance of approximately L, characterized in that said insertion slot (12) has a height of approximately T+A and in that said pair of guide rails (15) has a height A, thus being equal to the difference between a cassette having a height T+A and a cassette having the height T so that cassettes of a first set having a height T and widths L' or L, and cassettes of a second set having a height of T+A and widths L or L' respectively, upon insertion normally are correctly accomodated on said cassette tray (7), and in that said insertion slot (12) further includes a plurality of cassette detecting means (16a,16b,16c) mounted at an upper inner portion of said slot (12) for providing detection signals for monitoring the correct position of the cassettes within the cassette insertion slot (12). The system of claim 1, wherein said guide rails (15) provided on the cassette tray (7) are chamfered or rounded at the cassette receiving ends thereof. The system of claim 1 or 2, wherein said cassette transport means further includes a discrimination means (17) for discriminating whether a cassette has been correctly inserted into said cassette tray (7) by means of said detection signals obtained from said plurality of cassette detecting means (16a,16b,16c). The system claimed in one of claims 1-3, wherein said grooves (14) of said second type cassette (10b) to be engaged with the guide rails (15) of the cassette tray (7) are chamfered or rounded at the leading end for entrance into the mechanism. The system as in one of claims 1-4, wherein said grooves (14) of said second type tape cassette are partially spread at leading ends thereof for insertion on said guide rails (15) of said cassette tray (7). The system as in one of claims 1-5, wherein said first type grooveless tape cassette (10a) has an upper portion and a lower portion narrower than said upper portion, said lower portion having said width L which is to be guided between said pair of guide rails (15), said upper portion having a width greater than said width L, said lower narrower portion having a height greater than the height of each of said guide rails (15). The system as in one of claims 1-6, wherein said plurality of cassette detecting means (16a,16b,16c) comprises first and second cassette detectors (16a,16c) provided at said upper inner portion of said cassette insertion slot (12) opposite said guide rails and a third cassette detectors (16b) interposed between said first and second cassette detectors.

Inventors: INOUE MIKIHISA, KAKU NOBUYUKI, MAEHARA YOSHIMI, MASUDA NORIAKI, ONO SEIJI, INOUE, MIKIHISA, KAKU, NOBUYUKI, MAEHARA, YOSHIMI, MASUDA, NORIAKI, ONO , SEIJI, INOUE, MIKIHISA, HITACHI MAXELL, LTD., MASUDA, NORIAKI, GREEN PARK, Ono , Seiji Hitashi Seshiria Nagatadai
Applicants: HITACHI LTD, HITACHI MAXELL, HITACHI MAXELL LTD., HITACHI, LTD.
Application year: 1992
Main classification: G11B23
IPC codes: G11B23, G11B25, G11B15