GB2197523A - Automatic stop mechanism for tape recorder - Google Patents

Abstract

When a magnetic tape has been wound up fully on a take-up reel on shaft 5, slipping takes place between a gear 6 and shaft 5 so that the reel shaft 5 stops and a contact portion 32 of a cam follower 31 is no longer biased to contact a cam surface 11 but separates therefrom and contacts cam 12. The fulcrum of cam follower 31 is fixed and a turnable lever 7 then turns clockwise whereby drive gear 4 of a gear set 3, 4 separates from gear 6 and bent end portion 9 presses a lug 22 of a lock member 20 towards the left. Head mounting plate 17 is hence released from engagement with lock member 20 and allowed to return to its non-operated position, thereby allowing magnetic head 16 to return to its stop position. Rewind button e effects contact of lug c with bent end portion 9 to turn lever 7 to disengage gears 4,6. The lock member carries the shaft (8) of the gear set (3, 4) in an alternative embodiment (Fig. 2). In a third embodiment (Fig. 3) the recorder is also stopped in the rewinding mode. <IMAGE>

Description

SPECIFICATION Automatic stop mechanism for tape recorder BACKGROUND OF THE INVENTION 1) Field of the Invention: This invention relates to an automatic stop mechanism for a tape recorder, in which in the playback, fast feeding or rewinding mode, a playback, fast feeding or rewinding control member is allowed to return automatically to its non-actuated position when a magnetic tape has been fully wound up.

2) Description of the Prior Art: As automatic stop mechanisms for tape recorders, there have heretofore been known those detecting electrically each end of a tape to energize a solenoid so that a control member such as playback, fast feeding or rewinding control member is allowed to return from its actuated position to its non-actuated position; those making use of a rotary force of a flywheel or the like to cause such a control member to return to its non-actuated position; etc.

Automatic stop mechanism in each of which each end of a tape is electrically detected to stop the associated tape recorder automatically by means of a solenoid have complex structures due to the incorporation of solenoids and are also disadvantageous in reducing the dimensions of the associated tape recorders.

Turning next to automatic stop mechanisms making use of the rotary force of a flywheel to reverse the running direction of a tape, they generally have such as structure that a pin is provided upright from a portion of the flywheel and a lock member holding a playback, fast feeding or rewinding control member at its actuated position is kicked. This structure is thus accompanied by such drawbacks that the balance of the flywheel may be impaired and since the tension of the tape becomes higher temporarily at the beginning of each operation, this increased tension may be detected to cause a false operation.In conventional mechanisms of this type, a detection member adapted for detection of the tension of a tape is interlocked with the advancing and retreating displacement of the associated magnetic head and is allowed to contact with the tape only when the magnetic head has advanced and is maintained in contact with the tape. They are hence accompanied by such an inconvenience that the tape recorder cannot be automatically stopped in the fast feeding and rewinding mode.

SUMMARY OF THE INVENTION With the foregoing in view, the present invention has as its principal object the provision of an automatic stop mechanism for a tape recorder, which mechanism can automatically stop the tape recorder without need for accessory parts such as solenoids and hence facilitates the size reduction of the tape recorder, is free from adverse effects to the balance of flywheels and false operations, and moreover, can be actuated even in such an operation mode as fast feeding or rewinding mode.

In one aspect of this invention, there is hence provided an automatic stop mechanism for a tape recorder, comprising: pushing and urging means provided on a reel shaft at a position other than the center of the reel shaft; a rotation transmitting member for transmitting a rotary force of a capstan to the reel shaft via a friction mechanism; an eccentric cam surface and cam provided about the shaft of the rotation transmitting member;; a cam follower having a contact portion at a part thereof, and while the reel shaft is being rotated, being urged by the pushing and urging portion so as to maintain the contact portion thereof in sliding contact with the cam surface and hence to maintain the contact portion out of contact with the cam, but when the reel shaft is stopped and the contact portion assumes a position apart from the cam surface due to elimination of the urging force of the pushing and urging portion, being brought into contact at the contact portion thereof with the cam so as to displace the rotation transmitting member to a non-engagement position where the rotation transmitting member is maintained out of engagement with the reel shaft;; a control member displaceable back and forth between a non-actuaed position and an actuated position, said control member being urged normally toward the non-actuated position but upon displacement to the actuated position, being capable of maintaining the capstan in a rotated state; and a lock member for holding the control member at the actuated position but upon displacement of the rotation transmitting member to the non-engagement position, releasing the control member in association with the displacement of the rotation transmitting member, thereby to allow the control member to return to the non-actuated position.

In the above construction, the lock member does not release the control member as long as the reel shaft is in rotation. As soon as the reel shaft stops, the lock member serves to release the control member. Accessory parts such as solenoids are therefore not required, thereby facilitating the size reduction of a tape recorder.

Furthermore, the automatic stop mechanism of this invention is free from such dangers that the balance of rotation of the flywheels may be deleteriously affected and false oper ations may take place at start or the like.

The automatic stop mechanism of this invention is operated upon detection of stopping of the reel shaft irrespective of the position of the magnetic head. It is therefore free from any false operation even when the tension of a tape becomes high temporarily at start. In any operation mode, i.e., in any one of the playback mode, recording mode, fast feeding mode, rewinding mode and the like, the automatic stop mechanism of this invention can therefore stop the tape recorder whenever the tape has been fully wound up.

The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of an automatic stop device according to the first embodiment of this invention; Figure 2 is a schematic illustration of an automatic stop device according to the second embodiment of this invention; and Figure 3 is a schematic illustration of an automatic stop device according to the third embodiment of this invention; DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS First of all, the first embodiment of this invention will be described with reference to Fig. 1.

A capstan 1 is driven by an unillustrated motor. The rotation of the capstan 1 is transmitted, via a small diameter gear 2 provided coaxially with the capstan 1 and a combination of large diameter gear 3 and small diameter gear 4 (rotation transmitting member) provided coaxially as unitary members, to a gear 6 provided coaxially with a reel shaft 5.

The rotation is transmitted further to the reel shaft 5 by way of an unillustrated friction mechanism. The above combination of the large diameter gear 3 and small diameter gear 4 are supported via a shaft 8 on one end of a turnable lever 7 which is turnable about the capstan 1. The turnable lever 7 terminates in a bent end portion 9 at the other end and is normally biased by a tension spring 10 in such a direction that the large diameter gear 3 is brought into meshing engagement with the gear 6.

In the large diameter gear 3, an eccentric cam surface 11 is formed around the shaft 8.

A cam 12 projects from and in continuation with the shaft 8 at a position where the eccentric cam surface has the maximum radius.

Designated as numeral 13 is a pinch roller, which is supported on a bracket 15. The bracket 15 is turnable about a pivot 14 so that the pinch roller 13 can be releasably brought into contact wih the capstan 1.

Numeral 16 indicates a magnetic head, which is mounted on a head mounting plate 17 provided in such a way that the heat mounting plate 17 can be selectively advanced or retreated in the vertical direction as viewed in Fig. 1. Upon advancing or retreating displacement of the head mounting plate 17, the head 16 is brought into contact with a magnetic tape (not illustrated) or separated from the magnetic tape. The head mounting plate 17 is equipped at the rear end thereof (namely, the lower end thereof as viewed in Fig. 1) with a push button 18. The head mounting plate 17 is normally biased in its retreating direction by tension springs 19,19 but when a pushing force is applied to the push button 18, the head mounting plate 17 is caused to advance forward. The head mounting plate 17 and the above-described bracket 15 are interlocked.When the head mounting plate 17 advances and the magnetic head 16 is brought into contact with the magnetic tape, the pinch roller 13 is pressed against the capstain 1. On the other hand, when the head mounting plate 17 retreats and the magnetic head 16 is separated from the magnetic tape, the pinch roller 13 is also separated from the capstan 1. Since this type of interlocking mechanism is conventional, its description is omitted herein.

Numeral 20 indicates a plate-like lock member which is slidable horizontally as viewed in Fig. 1. The lock member 20 is normally biased in the rightward direction by a tension spring 21. The lock member 20 is equipped with a lug 22 positioned on the path of movement of the bent end portion 9 of the turnable lever 7. The lock member 20 is also equipped with hook portions 26,27 which correspond respectively to an engagement pin 23 provided upright on the head mounting plate 17 and another engagement pin 25 secured upright on a fast feeding control member 24.

When the engagement pin 23 and hook portion 26 or the engagement pin 25 and hook portion 27 are brought into engagement, the head mounting plate 17 or fast feeding control member 24 is held at its actuated position.

Incidentally, the fast feeding control member 24 is also displaceable in the vertical direction, as viewed in Fig. 1, like the head mounting plate 17. The fast feeding control member 24 is normally biased by an unillustrated tension spring toward its unactuated position.

On a shaft common to the reel shaft 5, there is mounted a rotary member 28 which rotates as a unitary member with reel shaft 5.

Pin-like pushing and urging means 29 is fixed on the rotary member 28. Although not illustrated in Fig. 1, a friction mechanism is interposed between the reel shaft 5 and the large diameter gear 6 so that the large gear 6 is allowed to rotate, for example, even after the reel shaft 5 is stopped. In this case, sliding takes place in the friction mechanism.

Designated at numeral 30 is a fixing plate, on which a cam follower 31 is pivotally mounted.

The cam follower 31 has a contact portion 3 at the farthest position from the fulcrum and also a pressure receiving portion 33 positioned on the path of rotation of the pushing and urging means 29.

Numeral 34 indicates a flywheel mounted fixedly on the capstan 1.

The operation of the automatic stop mechanism according to the first embodiment of this invention will next be described.

In Fig. 1, the head mounting plate 17 has moved forward and the engagement pin 23 has been brought into engagement with the hook portion 26 of the lock member 20, whereby the magnetic head 16 is maintained at the actuated position thereof. Further, the pinch roller 13 has been pressed against the capstan 1, so that the rotation of the capstan, the direction of which is indicated by an arrow, is being transmitted to the reel shaft 5 via the gears 2,3,4,6 and the unillustrated friction mechanism and the tape recorder is therefore operated in its playback mode (note the omission of the magnetic tape in the drawing).

At this time, the rotary force of the reel shaft 5 is being transmitted to the cam follower 31 by way of the pushing and urging means 29 and the contact portion 32 of the cam follower 31 is maintained in sliding contact with the cam surface 11. As long as the contact portion 32 is maintained in sliding contact with the cam surface 11 in the abovementioned manner, the contact portion 32 and cam 12 will not contact to each other.

When the tape has next been wound up fully on the reel, slipping takes place in the friction mechanism interposed between the large diameter gear 6 and reel shaft 5 so that the reel shaft 5 stops. As a consequence, the contact portion 32 which has been maintained in sliding contact with the cam surface 11 is caused to separate from the cam surface 11 at a location closest to the shaft 8 and the cam 12 is hence brought into contact with the contact portion 32. Since the fulcrum of the cam follower 31 is fixed, the turnable lever 7 is then caused to turn clockwise against the spring 10 so that the gear 4 is separated from the large diameter gear 6.

On the other hand, by the turning motion of the turnable lever 7, the bent end portion 9 of the turnable plate 6 presses the lug 22 of the lock member 20 from the right as viewed in Fig. 1, thereby shifting the lock member 20 in the leftward direction. Accordingly, the head mounting plate 17 is released from its engagement with the lock member 20 and is hence allowed to return to the non-actuated position by the springs 19, whereby the magnetic head 16 is allowed to return to its stop position.

As a modification of the first embodiment, the pressure receiving part 33 of the cam follower 31 can be extended as indicated by dotted lines. Additional pushing and urging means 29' is also provided fixedly on the rotary member 28 at a position antipodal to the pushing and urging means 29. Further, an additional lug c is provided on the lock bar 20.

An engagement pin a is also provided upright on the head mounting plate 17. Its matching hook portion b is formed in the lock bar 20.

In the playback or fast feeding mode, the gears 6 and 4 are maintained in meshing engagement while the gears 3 and 2 are also maintained in meshing engagement as shown in Fig. 1. The capstan 1 and pinch roller 13 are brought into engagement only in the playback mode. For performing the rewinding mode, it is necessary to push a rewinding button e so that the engagement pin a and hook portion b are brought into engagement and a reel shaft 5' is rotated to rewind the unillustrated magnetic tape on its associated reel. The degree of displacement of the lock bar 20 at this time is set greater than that in the playback or fast feeding mode. Accordingly, the lug c is brought into contact with the bent end portion 9 so that the lever 7 is caused to turn. This turning angle of the lever 7 is set at a small value sufficient only to disengage the gears 6 and 4 from each other.

When the clockwise rotation of the gear 6 stops, the lock bar 20 is shifted to release the locking in the same operation as in the playback or fast feeding mode.

The second embodiment of this invention will next be described with reference to Fig.

2.

In the second embodiment, the turnable lever 7 and lock member 20 of the first embodiment are provided as an integral member, in other words, one end of a lock member 40 is extended to a point close to the reel shaft 5 and the combination of the large diameter gear 3 and small diameter gear 4 are supported on the thus-extended end portion of the lock member 40.

In the above construction, when the contact portion 32 of the cam follower 31 is brought into contact with the cam 12, the lock member 40 is caused to slide rightward as viewed in Fig. 2 so that the large diameter gear 3 and small diameter gear 4 are separated from the small diameter gear 2 and large diameter gear 6 respectively.

The lock member 40 is normally biased by the tension spring 21 in the leftward direction, namely, in such a direction that the large diameter gear 3 and small diameter gear 4 are brought into meshing engagement with the small diameter gear 2 and large diameter gear 6 respectively. The lock member 40 includes hook portions 41, 42 which correspond respectively to the engagement pints 23,25 of the head mounting plate 17 and fast feeding control member 24 respectively. When the engagement pin 23 or 25 is in engagement with the hook portion 41 or 42, they can be disengaged by causing the lock member 40 to slide in a direction opposite to the biased direction.

Thus, the head mounting plate 17 or fast feeding control member 24 is alowed to return from the actuated position to the nonactuated position. The second embodiment of this invention can therefore bring about the same advantages as the first embodiment.

The third embodiment of this invention will next be described with reference to Fig. 3.

In the third embodiment, the tape recorder can be stopped automatically even in the rewinding mode.

Namely, a take-up reel shaft 5a and a rewinding reel shaft 5b are both provided with rotary members 28a,28b respectively. The rotary members are in turn provided with pushing and urging means 29a,29b respectively.

On an elongated fixing plate 50 extending from the take-up reel shaft 5a to the rewinding reel shaft 5b, a cam follower 51 is mounted turnably. From the fulcrum of the cam follower 51, a contact portion 52 adapted for sliding contact with the eccentric cam surface 11 and pressure receiving portions 53a,53b, which correspond to the pushing and urging portions 29a,29b respectively, extend out radially.

Numeral 54 indicates a playback control member, while numerals 55 and 56 indicate a fast feeding control member and rewinding control member respectively. Engagement pints 57,58,59 are provided upright on the individual control members 54,55,56 respectively.

Designated at numeral 60 is a lock member slidable horizontally as viewed in Fig. 3. The lock member 60 is normally biased in the rightward direction by the tension spring 21.

This lock member 60 is provided with a lug 61, which is positioned on the path of movement of the bent end portion 9 of the turnable lever 7, and also with hook portions 62,63,64 which correspond to the engagement pins 57,58,59 respectively. Upon engagement between the engagement pin 57 and hook portion 62, the engagement pin 58 and hook portion 63 or the engagement pin 59 and hook portion 64, the playback control member 54, fast feeding control member 55 or rewinding control member 56 is maintained at its actuated position. Each of the control members are provided displaceably up and down as viewed in Fig. 3 but are normally biased by their corresponding unillustrated springs toward their respective non-actuated positions.

In the above construction, when the reel shaft 5b has stopped even in the rewinding mode, to say nothing of the playback or fast feeding mode, the contact portion 52 of the cam follower 51 is brought into contact with the cam 12 so that the turnable lever 7 is caused to turn clockwise to slide the lock member 60 in the leftward direction, thereby to stop the tape recorder automatically.

There has been described an automatic stop mechanism for a tape recorder, comprising: pushing and urging means provided on a reel shaft at a position other than the center of the reel shaft; a rotation transmitting member for transmitting a rotary force of a capstan to the reel shaft via a friction mechanism; an eccentric cam surface and cam provided about the shaft of the rotation transmitting member;; a cam follower having a contact portion at a part thereof, and while the reel shaft is being rotated, being urged by the pushing and urging portion so as to maintain the contact portion thereof in sliding contact with the cam surface and hence to maintain the contact portion out of contact with the cam, but when the reel shaft is stopped and the contact portion assumes a position apart from the cam surface due to elimination of the urging force of the pushing and urging portion, being brought into contact at the contact portion thereof with the cam so as to displace the rotation transmitting member to a non-engagement position where the rotation transmitting member is maintained out of engagement with the reel shaft; ; a control member displaceable back and forth between a non-actuated position and an actuated position, said control member being urged normally toward the non-actuated position but upon displacement of the actuated position, being capable of maintaining the capstan in a rotated state; and a lock member for holding the control member at the actuated position but upon displacement of the rotation transmitting member to the non-engagement position, releasing the control member in association with the displacement of the rotation transmitting member, thereby to allow the control member to return to the non-actuated position.

Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.

Claims (9)

1. An automatic stop mechanism for a tape recorder, comprising a rotation transmitting member for transmitting a rotary force of a capstan to a reel shaft via a friction mechanism, an eccentric cam surface provided about a rotary shaft of the rotation transmitting member, and an engagement portion provided with the rotation transmitting member, a reel-shaft stop detecting means for detect ing each stop of the reel shaft, said means comprising a cam follower having a contact portion, the cam follower being arranged to receive a biasing force generated while the reel shaft is being rotated, thereby to maintain the cam follower in sliding contact with the eccentric cam surface and hence to avoid engagement between the contact portion of the cam follower and the engagement portion, but when the reel shaft stops and the cam follower remains at a position apart from the eccentric cam surface, said engagement portion is brought into contact with the contact portion of the cam follower so as to displace the rotation transmitting member to an inoperative position, a control member displaceable back and forth between a non-operated position and an operated position, said control member being biased toward the non-operated position normally but at the operated position, maintaining the capstan in a reel shaft driving state, and a lock member for holding the control member at the operated position but upon displacement of the rotation transmitting member to the inoperative position, releasing the control member responsive to the displacement of the rotation transmitting member, thereby to allow the control member to return to the non-operated position.

2. The automatic stop mechanism as claimed in claim 1, wherein the cam follower also serves as the contact portion.

3. The automatic stop mechanism as claimed in claim 1, wherein the reel-shaft stop detecting means further comprises a rotatable member turnable about a shaft common to the reel shaft, the rotatable member has pushing and urging means provided at a position other than the center thereof, and the biasing force generated by rotation of the reel shaft is transmitted to the cam follower via the pushing and urging means.

4. An automatic stop mechanism for a tape recorder comprising a rotation transmitting gear for transmitting rotation of a capstan to a reel shaft via a friction mechanism, a concavely curved, circular cam surface on said rotation transmitting gear and eccentric about the shaft of the gear, a camming projection on said gear shaft and projecting towards the circular cam surface at the position of maximum radius of the circular cam surface, a reel shaft stop detecting means for detecting each stop of the reel shaft, said stop detecting means comprising a rotatable member turnable about a shaft common to the reel shaft, pushing and urging means on the rotatable member at a position displaced from the centre thereof, a cam follower having a contact portion, the cam follower being arranged to receive the biasing force of the pushing and urging means generated only so long as the reel shaft is being rotated, thereby to maintain the cam follower in sliding contact with the circular cam surface and hence avoiding engagement between the contact portion of the cam follower and said camming projection, but when the reel shaft stops, and the cam follower remains at a position apart from the circular cam surface, said camming projection is brought into contact with said contact portion of the cam follower so as to displace said rotation transmitting gear to an inoperative position, a control member displaceable back and forth between a non-operated position and an operated position, said control member being biased toward the non-operated position but at the operated position, maintaining the capstan in a reel shaft driving state, and a lock member for holding the control member at the operated position but upon displacement of the rotation transmitting gear to the inoperative position, releasing the control member responsive to the displacement of the rotation transmitting gear, thereby to allow the control member to return to the non-operated position, said rotation transmitting gear shaft being carried by a turnable lever, said lever being biased to turn in a direction to move said rotation transmitting gear to an operative, reel shaft driving position, but operating to displace said lock member to release said control member when the rotation transmitting gear is displaced to its inoperative position.

5. An automatic stop mechanism for a tape recorder comprising a rotation transmitting gear for transmitting rotation of a capstan to a reel shaft via a friction mechanism, a concavely curved, circular cam surface on said rotation transmitting gear and eccentric about the shaft of the gear, a camming projection on said gear shaft and projecting towards the circular cam surface at the position of maximum radius of the circular cam surface, a reel shaft stop detecting means for detecting each stop of the reel shaft, said stop detecting means comprising a rotatable member turnable about a shaft common to the reel shaft, pushing and urging means on the rotatable member at a position displaced from the centre thereof, a cam follower having a contact portion, the cam follower being arranged to receive the biasing force of the pushing and urging means generated only so long as the reel shaft is being rotated, thereby to maintain the cam follower in sliding contact with the circular cam surface and hence avoiding engagement between the contact portion of the cam follower and said camming projection, but when the reel shaft stops, and the cam follower remains at a position apart from the circular cam surface, said camming projection is brought into contact with said contact por tion of the cam follower so as to displace said rotation transmitting gear to an inoperative position, a control member displaceable back and forth between a non-operated position and an operated position, said control member being biased toward the non-operated position but at the operated position, maintaining the capstan in a reel shaft driving state, and a lock member for holding the control member at the operated position but upon displacement of the rotation transmitting gear to the inoperative position, releasing the control member responsive to the displacement of the rotation transmitting gear, thereby to allow the control member to return to the non-operated position, said rotation transmitting gear shaft being carried by said lock member, said lock member being biased to move said rotation transmitting gear to an operative, reel shaft driving position.

6. An automatic stop mechanism for a tape recorder comprising a take-up reel shaft, a rewinding reel shaft, a rotation transmitting gear for transmitting rotation of a capstan to said take-up reel shaft via a friction mechanism, a concavely curved, circular cam surface on said rotation transmitting gear and eccentric about the shaft of the gear, a camming projection on said gear shaft and projecting towards the circular cam surface at the position of maximum radius of the circular cam surface, a reel shaft stop detecting means for detecting each stop of said take-up reel shaft while rotating in one direction and each stop of said re-winding reel shaft while rotating in the opposite direction, said reel shaft stop detecting means comprising a cam follower having a contact portion, the cam follower being arranged to receive a biasing force generated by rotation of said take-up reel shaft while said take-up reel shaft is being rotated in said one direction and a biasing force generated by rotation of said re-winding reel shaft while said re-winding reel shaft is being rotated in said opposite direction thereby to maintain the cam follower in sliding contact with the circular cam surface and hence avoiding engagement between the contact portion of the cam follower and said camming projection, but when the reel shafts stop and the cam follower remains at a position apart from said circular cam surface, said camming projection is brought into contact with said contact portion of the cam follower so as to displace said rotation transmitting gear to an inoperative position, playback and rewind control members displaceable back and forth each between a nonoperated position and an operated position, said control members being biased towards their non-operated positions but at their operated positions each maintaining the capstan in a reel shaft driving state, and a lock member for holding each control member at its operated position but upon displacement of the rotation transmitting gear to the inoperative position releasing the control member responsive to the displacement of the rotation transmitting gear, thereby to allow the control member to return to the non-operated position.

7. An automatic stop mechanism for a tape recorder substantially as either one of the embodiments hereinbefore described with reference to, and as shown in Fig. 1 of the accompanying drawings.

8. An automatic stop mechanism for a tape recorder substantially as hereinbefore described with reference to, and as shown in, Fig. 2 of the accompanying drawings.

9. An automatic stop mechanism for a tape recorder substantially as hereinbefore described with reference to, and as shown in, Fig. 3 of the accompanying drawings.