Automatic return device for use in cassette tape recorder
BACKGROUND OF THE INVENTION 
     The present invention relates to a return device for use in a cassette tape recorder and more particularly to a mechanical return device using tape tension. 
     BRIEF REVIEW OF THE PROBLEM 
     Generally, a cassette tape is recorded on the upper portion of the tape or A side and the lower portion or B side thereof. For playing the recorded tape, the tape is loaded in a tape recorder, and the switch is turned to the on position of the recorder to have the tape play in the cassette. When the tape has been completely rolled up in one direction, a lever is pressed by the increased tape tension, thereby automatically stopping the rotary driving of the tape recorder and shutting off the power supply simultaneously. 
     To playback the A-side recording on the tape rolled up in one direction, it is necessary to rewind the tape by actuating a fast-reverse pushbutton to turn on a switch. And when the tape recorder is installed inside an automobile, it is dangerous while driving the automobile. 
     In an attempt to eliminate these defects, the inventor has provided a device capable of returning the tape automatically to the former state without the need of touching the tape recorder. 
     SUMMARY OF THE INVENTION 
     An object of the invention resides in providing an automatic return device for use in a tape recorder to reverse a rotatory driving means mechanically by utilizing increased tape tension occurring when a cassette tape has been rolled up to the end in one direction. 
     The rotatory driving means is reversed merely by pure mechanical operation without any electrical action so as to eliminate variations resulting from ambient temperature or humidity, thereby achieving reliability as well as safety and service life which are requirements for the tape recorder&#39;s function and to avoid wasteful consumption of power. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of an automatic return device for use in a tape recorder embodying the present invention; and FIG. 2 is a front view of a principal portion of the device shown in FIG. 1 with some components removed to illustrate the operation of the inventive concept. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter an embodiment of the present invention will be described in detail with reference to the accompanying drawings, in which: (1) is a motor; (2,2a) are flywheels of light alloy, on whose axes wear-resisting capstan shafts (3, 3a) are provided; (4, 4a) are pinch rollers made of metal or synthetic rubber and pivoted to frames (29, 29a) respectively in a rotatable manner on a chassis (28). The frames (29, 29a) are elastically energized by means of springs (not shown) so that the ends (30, 30a) of frames (29, 29a) butt against actuating parts (31, 31a) of a reverse lever (11), which will be described afterward; (5) is a metallic or plastic gear, whose shaft has mounted thereon a metallic or plastic pulley (6) coaxially; (7) is a metallic or plastic gear having notches (8, 8a) on the circumference thereof and being so disposed as to engage with the gear (5) when rotated; (9, 9a) are pins disposed symmetrically on one side of the gear (7); and (10) is a pin provided eccentrically between the center of gear (7) and one of the pins (9, 9a). The notches (8, 8a) on the circumference of gear (7) are positioned diametrically opposite each other. (11) is a metallic reverse lever with one end engaged with the pin (10) while other end formed into actuating parts (31, 31a) is engageable with the ends (30, 30a) of frames (29, 29a) which hold the pinch rollers (4, 4a); (11a) is the fulcrum of the reverse lever (11); (12) is a sensing lever having a plastic sensing part (12a) and being pivoted at a fulcrum (15) with one end connected to a lock lever (14) through a coupling pin (13); (14a) is a fulcrum of the lock lever (14); (16) is a pull spring for the lock lever (14); (17) is a pull spring for the sensing lever (12); (18, 18a) are reel tables; (19) is a roller; (20) is a roll-up pulley; (21) is a roll-up roller disposed coaxially with the roll-up pulley (20) and connected to a roller arm (22) which serves to bring the roll-up roller (21) into intimate engagement with the reel table (18). The roller arm (22) is rotatably pivoted at a pin (32) as illustrated, and a belt (24) threading through the roller (20) serves to push the roller arm (22) leftward. (23) is an elastic part extending at the end of roller arm (22) and being kept in engagement with a recess formed at the end of reverse lever (11); (24, 24) are belts, one threading through the pulley (1a) mounted coaxially with the motor (1) and the gear (5), while the other threading through the pulley (1a), the flywheels (2, 2a) and the roll-up pulley (20); (25) is a cassette tape; (26) is a chassis; (27) is a playback head mounting plate; and (28) is a guide pin. 
     How a description will be given on the operation of the present invention. In the state where a known cassette tape (25) has been rolled up to the end in one of the reels, the sensing part (12a) of sensing lever (12) comes to be pressed with increased tension of the tape (25) tensed horizontally as illustrated by the two-dot chain line, so that the sensing part (12a) is pushed upward in the drawing to rotate the sensing lever (12) counterclockwise around the fulcrum (15) as shown in FIG. 2. As a result, the lock lever (14) is pushed downward by the coupling pin (13) so as to be disengaged from the pin (9a). When unlocked from the pin (9a), the reverse lever (11) is shifted in the direction shown by the arrow a, and an inclined surface (33) at the end of reverse lever (11) pushes the pin (10) in the direction of the arrow b through slide contact therewith. The shift of pin (10) in the direction b causes the gear (7), where the pin (10) is mounted, to start clockwise rotation. So that, the gear (7) comes into engagement with the gear (5) which is positioned in the notch (8) of gear (7) and the rotating in the direction c. Consequently, the gear (7) engaged with the gear (5) is rotated in the direction of the arrow b. As a result, the reverse lever (11) holding the pin (10) of gear (7) is rotated clockwise in accordance with the rotation of gear (7) as shown by the two-dot chain line. And simultaneously, one of the two pinch rollers (4, 4a) being in engagement with the other ends (31, 31a) of reverse lever (11), one roller (4) is rotated in the direction to move away from the capstan shaft (3), while the other roller (4a) is rotated in the direction to be pressed against the capstan shaft (3a). In this case, a rotatory force is applied to the roller arm (22) by the engaging part of reverse lever (11) so as to rotate the arm around the pin (32). By such operation, the contact between the reel table (18) and the roll-up roller (21) through the roller (19) is shifted to the contact between the reel table (18a) and the roll-up roller (21). This shift causes a roll-up torque by means of a clutch (not shown) mounted in the roll-up pulley (20). When the gear (7) is rotated 180°, the foregoing operation is terminated, and simultaneously the tape (25) starts running in the reverse direction. Thus, the gear (5) is fitted to the notch (8a) of gear (7), and the lock lever (14) is brought into engagement with the pin (9) to stop the rotation of gear (7). Thereby, the tape (25) is kept running in reverse. While the tape is running in the reverse direction, the gear (5) is idle rotation. 
     At each termination of rolling up the tape (25) to the end, the gear (7) is rotated 180° by the foregoing operation to effect automatic return rolling of the tape (25).