Abstract:
An idling rotation mechanism used in a video tape recorder (VTR) to mount and dismount a video cassette tape (VCT) by using only a loading motor. The VCT is mounted and dismounted by moving a holding pin, connected to a VCT holder, along a slot in a support plate. The pin is connected to a idling rotation mechanism that is connected to the loading motor. To prevent the VCT from becoming jammed in the VTR because of excessive rotation of the loading motor, a timing gear in the idling rotation mechanism idles after the pin has been partially moved in the slot.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an idling rotation mechanism, used in the housing of a video cassette tape recorder (VTR), which comprises cams and gears provided on the outside of the housing to mount and dismount a video cassette tape (VCT). The idling rotation mechanism can rotate idly when the VCT is loaded or unloaded from the playback and recording tape heads. 
     Conventionally, a VTR includes a housing motor for moving the video cassette tape in and out of the VTR, and a separate loading motor for moving the inserted video cassette tape in and out of engagement with the playback and recording tape heads. The housing motor and the loading motor are separately driven during the initial operation and the final positioning of the VCT. 
     Thus, the conventional VTR, having a plurality of component elements for both the housing motor and the loading motor, becomes quite complicated. As a result of the added complication of a separate housing and loading motor, the rate of malfunctioning is quite high, repairs become more difficult, and the size and weight of the VTR must be increased to accommodate the added components. Consequently, it becomes difficult to make a compact and light VTR having both a loading motor and a housing motor. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide an idling rotation mechanism, used in the housing of a VTR, which simplifies the component elements so that a singular loading motor can mount and dismount a VCT from the VTR as well as load and unload the VCT from the playback and recording tape heads. Another object of the present invention is to provide an idling rotation mechanism that can idly rotate when the VCT is being loaded and unloaded. 
     The idling rotation mechanism of the present invention is preferably used in a front loading VTR, for recording and reproducing video signals on a magnetic tape, and comprises: 
     a motor; 
     a speed-variation means drivingly connected to the output shaft of said motor to vary the transmitted rotational speed thereof; and 
     a drive means for a cassette transporting holder having means for cutting off rotation of the drive means, said means for cutting off rotation is operatively associated with said speed-variation means and actuated by a rotational force of said motor to cut off transmission of the rotational force of said motor and prevent the cassette transporting holder from moving any further after the cassette tape has been loaded in the deck. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a tape recorder housing of the present invention; 
     FIG. 2A is a side view illustrating a VCT inserted into the idling rotation mechanism of the present invention; 
     FIG. 2B is a perspective view illustrating assembly of the essential parts of the present invention; 
     FIG. 2C is an exploded perspective view illustrating the essential parts of the present invention; 
     FIG. 3 is a side view of the tape recorder housing of the present invention illustrating the initial stage before a VCT is inserted into the VTR; and 
     FIG. 4 is a side view illustrating the tape recorder housing of the present invention after a VCT has been loaded into the VTR. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described specifically with reference to the attached drawings. 
     FIG. 1 is a plan view of a VTR housing 1 of the present invention, which shows a cassette switch 29 that is activated when VCT 32 is inserted into the VTR, and an idling rotation mechanism comprising an arm gear 13, a side arm 7, timing gear 19 and relay gear 6. Connected to side arm 7 is a guide pin 16 that is also connected to an inside holder 30. Guide pin 16 is moved along guide slot 5, in support plate 33, by side arm 7 so that inside holder 30 can mount and dismount the VCT 32 from the VTR. 
     FIG. 2A is a side view illustrating a VCT 32 being inserted into the idling rotation mechanism of the present invention. During insertion, VCT 32 first passes through entrance 31 of housing 1 and then moves past inlet 27 of holder 30 so as to be positioned in holder 30. 
     Referring to FIG. 2B, bevel gear 18 is shown, mounted to rotating shaft 4, having a small gear 18a mounted on the back side of bevel gear 18 so motor 26 to timing gear 19. 
     FIG. 2B also shows a timing gear 19, mounted to rotating shaft 3, having a gear part 19a and a rotating plate 19b. Gear part 19a further comprises a sliding part 19a&#39; whose length approximately amounts to the arc length of a half circle of gear part 19a. Moreover, sliding part 19a&#39; partially overlays the gear teeth of gear part 19a. Rotating plate 19b, however, is partially cut and, on one end of the perimeter thereof along edge part 19b&#39;, has a stopper 19&#39; projecting outwards. In addition, a guide hole 20, on rotating plate 19b, facilitates the alignment of arm gear 13 and timing gear 19 during the assembly of the idling rotation mechanism. Specifically, guide hole 20 is aligned, during assembly, with a portion of arm gear 13 so that the first tooth of geared part 13a can be properly positioned on gear part 19a for the coordinated rotation of arm gear 13 and timing gear. 
     As shown in FIGS. 2B and 2C, an arm gear 13, rotatably mounted on rotating shaft 2, has a geared part 13a formed partially along its perimeter. Furthermore, a pin 14 projects towards timing gear 19 from the end of geared part 13a. As the arm gear 13 is rotated during the mounting and loading of the VCT, when the geared part 13a of arm gear 13 becomes disengaged from the gear part 19a, sliding part 19a&#39;, that does not have any gear teeth, contacts the geared part 13a of arm gear 13 and further rotates the arm gear 13 by frictional contact so that pin 14 contacts edge part 19b&#39; of rotating plate 19b. 
     Also shown in FIGS. 2B and 2C is side arm 7. Side arm 7 is mounted to rotating shaft 2 so as to be coaxially mounted with respect to arm gear 13. Moreover, side arm 7 has a gear portion 12 formed on its perimeter so as to engage relay gear 6, a stopper 12a projecting inwardly from gear portion 12 so as to abut stop 21 on the beginning of geared part 13a, and a projecting lug 12b formed on the opposite side of gear portion 12 so as to project towards arm gear 13. Thus, the excessive rotation of side arm 7, with respect to arm gear 13, will result in projecting lug 12b contacting arm gear 13. 
     Side arm 7 also comprises a spring holder 17 that, in conjunction with spring holder 15 on arm gear 13, holds ejector spring 17c so that stop 21 and stopper 12a can be in an abutting arrangement. Side arm 7 also has a gripper 9 to grip guide pin 16 which is connected with the inside holder 30. A boss 8, formed on the inner side of gripper 9, projects from side arm 7 so as to hold torsion spring 11 in conjunction with torsion spring holders 10. FIGS. 3 and 4 show bevel gear 18 engaged with an ejector gear 22 mounted inside a deck 23. Deck 23 is a structural piece of the VTR and holds the loading system assembly as well as the recording and playback tape heads. Moreover, ejector gear 22 is connected with a loading motor 26 via worm 24 and worm gear 25. As a result of the above interaction of bevel gear 18, ejector gear 22, worm 24, and worm gear 25, the transmitted rotational speed of motor 26 can be varied. In addition, ejector gear 22 also engages master cam 35, connectable to a series of arms and gears that are connectable to a grabbing device (not shown), so that the magnetic tape of the VCT can be drawn in and out of engagement with the playback and recording tape head drum by the grabbing device of the loading system. 
     The operation of the above-described invention will be explained as follows. 
     As shown in FIGS. 2A, 2B, 3 and 4, when VCT 32 is inserted through entrance 31 and inlet 27, VCT 32 contacts cassette switch 29 which activates the loading motor 26. The rotation of the loading motor 26 is determined by a system controller circuit in the VTR. 
     Since worm 24 is connected to loading motor 26, the rotation of loading motor 26 causes worm 24, worm gear 25 and ejector gear 25 to rotate. The rotation of ejector gear 25 then causes bevel gear 18 and master cam 35 to be rotated in a counter-clockwise rotation. Small gear 18a then rotates timing gear 19, due to the connection between small gear 18a and gear part 19a, in the clockwise direction which in turn rotates arm gear 13, due to the connection between geared part 13a and gear part 19a, in the counter-clockwise direction. 
     As a result of the abutting arrangement between arm gear 13 and stopper 12a of side arm 7, and the mounting of arm gear 13 and side arm 7 coaxially on shaft 2, the rotation of arm gear 13 will cause side arm 7 to also be rotated in a counter-clockwise direction. Therefore, as side arm 7 rotates guide pin 16 is moved along slot 5 by gripper 9. Accordingly, holder 30 and VCT 32 are moved along with guide pin 16. While guide pin 16 is moving along guide slot 5, gear portion 12 of side arm 7 causes relay gear 6 to be rotated in the clockwise direction so as to close entrance 31 of the VTR as the VCT is moved into the VTR. 
     When guide pin 16 reaches position A on guide slot 5, gear part 19a becomes disengaged from geared part 13a and sliding part 19a&#39;, that does not have any gear teeth, contacts geared part 13a. The frictional contact between geared part 13a and sliding part 19a&#39; causes geared part 13a to rotate so as to complete the loading action by the inside system controller before pin 14 abuts stopper 19&#39;. Simultaneously, guide pin 16 is moved to position B. Then the loading motor is stopped. In this condition, if the timing gear 19 abnormally keeps on rotating, the stopper 19&#39; is obstructed by the pin 14 so as to prevent the timing gear 19 from rotating. 
     Hence, when the guide pin 16 is securely mounted in the position A of FIG. 4, during the initial mounting of the VCT and thereafter, the idling rotation is achieved with a frictional force, guide pin 16 is moved to position B so that holder 30 strongly receives the resilient force of the torsion spring 11 so to prevent the movement of the VCT. Once in position B, so that the VCT is located on the deck by the drive means, the magnetic tape of the VCT is withdrawn from the VCT by the grabber device of the loading system and placed into contact with the recording and playback tape head drum. 
     When unloading, the operation proceeds in the opposite direction to the above-mentioned process. Namely, the inside system controller circuit causes loading motor 26 to rotate in the opposite direction. Thereafter, loading motor 26 is driven for a few seconds so that timing gear 19 rotates in a counter-clockwise direction so as to dislodge pin 14 from edge portion 19b&#39;. Gear part 19a of the timing gear 19 then engages geared part 13a of arm gear 13 so that both timing gear 19 and arm gear 13 rotate. 
     With the arm gear 13 rotating, guide pin 16 moves back along the guide slot 5 to eject VCT 32 from the VTR. 
     As described above, a singular loading motor 26, mounts and loads, or unloads and dismounts, VCT 32 from the VTR. In addition, the idling rotation mechanism allows VCT 32 to be mounted accurately, yet prevents the VCT from being forced when loaded in the VTR. Moreover, irrespective of the operational changes of the system controller circuit, the idling rotation mechanism of the present invention is a relatively uncomplicated structure that is easily assembled, therefore, the rate of malfunctioning can be significantly reduced and the repairs easily performed. 
     The invention is in no wa limited to the example described hereinabove. Various modifications of the disclosed embodiment, as well as other embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention and the drawings. For example, the speed-varying elements could be partially or fully replaced by a pulley system. It is therefore contemplated that the appended claims will cover any such modifications or embodiments that fall within the true scope of the invention.