GB2237678A - Tape tensioning device for a tape recorder - Google Patents

Abstract

A tape tensioning device for a tape recorder which automatically eliminates possible slack in a tape within a tape cassette in response to loading of the tape cassette and without necessitating any additional manual operation. Upon loading of a tape cassette (5), a tape feeding motor (9) is energized by way of a cassette detecting switch (6) and a tape tensioning motor switch (8) to start its rotation, and the rotation is transmitted to a specific one reel spindle (2a) by way of a tape tensioning rotation transmitting means (25) while the other reel spindle (2b) is inhibited from rotation by a brake means (16), thereby absorbing possible slack in the tape (5b) to tension the tape (5b). A tension detecting means (37: 37a) detects the tensioned condition of the tape (5b) to move a controlling member (11) away from its home position to disconnect the tape tensioning rotation transmitting means (25), cancel the braked condition and switch the tape tensioning motor switch (8) off to deenergize the tape feeding motor (9) to stop rotation of the motor (9). <IMAGE>

Description

TAPE TENSIONING DEVICE FOR TAPE RECORDER This invention relates to a tape tensioning device for a tape recorder which automatically eliminates possible slack of a tape within a tape cassette in response to loading of the tape cassette in position into the tape recorder.

When a tape cassette is left unused for a considerable interval of tine, the magnetic tape within the tape cassette may unreel slacking fractionally due to vibrations of the cassette from the outside and so forth. If a tape cassette in such condition is loaded in position into a tape recorder and used, then there is the possibility that upon starting the slack tape may wind itself around a capstan or a pinch roller and the tape or the tape recorder may be damaged thereby.

Even from the fact that a large number of patent applications have been made so far as a countermeasure for the problem, it can be understood how seriously people having ordinary skill in the art have tackled the problem.

For example. the following patent publications all disclose countermeasures for the problem: Japanese Patent Publication Nos. 50-9408. 50-9409 and 50-13652: Japanese Patent Laid-Open No. 51-88007: Japanese Utility Model Publication Nos. 50-104, 50-15470. 50-27301, 50 35692. 52-48727 and 52-56804; and Japanese Utility Model Laid-Open Nos. 49-86821. 49-102709, 50-81808, 50-105407.

50-105408, 50-144607, 50-149010. 50-149011, 51-3311, 52 35207. 53-1311. 53-52114. 58-43655, 58-43656, and 5843657 However. the prior art devices either try to improve a mechanism around a pinch roller or a capstan so as to prevent a slack tape from entering between the pinch roller and the capstan or try to detect it without a moment's delay that a tape has wound itself around a pinch roller or a capstan.

The former has a drawback that it cannot prevent a tape from entering between a pinch roller and a capstan with certainty while the latter only notifies the fact that a tape has wound itself around a pinch roller or a capstan and does not make a fundamental solution. Besides, since neither of them tensions a tape, it is cumbersome that, when there is tape slack or a tape winds itself around a pinch roller or a capstan, the tape recorder must be stopped manually to promptly deal with the situations.

Japanese Utility Model Publication No. 1-27135 discloses a technique that, when a tape tensioning operation is performed, a brake for a reel spindle on the take-up side is released while the other reel spindle on the supply side is left braked by the other brake therefor in order to tension a tape.

However. this technique is cumbersome in that a special operation, that is, a tape tensioning operation.

must be performed on purpose in order to tension a tape.

It is an object of the present invention to provide a tape tensioning device for a tape recorder which automatically eliminates, when there is slack in a tape within a tape cassette, such slack in the tape in response to loading of a tape cassette in position into the tape recorder and without necessitating any additional manual operation.

In order to attain the object. according to the present invention, there is provided a tape tensioning device for a tape recorder of the type wherein a tape feeding motor is connected to a power source by way of a motor driving circuit for normal operation in response to selection of a tape recorder function with a tape cassette loaded in position on a pair of reel spindles of the tape recorder and rotation of the tape feeding motor is transmitted alternatively to either one of the reel spindles by way of a rotation transmitting means for normal operation to cause the tape recorder to operate in an operation mode corresponding to the selected tape recorder function, and the tape cassette is removed from the reel spindles in response to selection of a tape cassette ejecting function, the tape tensioning device comprising a cassette detecting switch of the normally open type which is closed and held closed by the tape cassette loaded in position on the reel spindles, a tensioning motor switch connected in series to the cassette detecting switch for connecting the tape feeding motor to -the power source, a tape tensioning rotation transmitting means for transmitting turning force of the tape feeding motor to a specific one of the reel spindles, a brake means for inhibiting rotation of the other specific reel spindle, a controlling member having a home position at which the brake means and the tensioning rotation transmitting means assume individual operative positions and the tape tensioning motor switch assumes a closed position, a spring means for resiliently biasing the controlling member to the home position. a tension detecting means for either detecting stopping of the specific one reel spindle or detecting an increase of tension of the tape between the reel spindles to move the controlling member away from the home position against the biasing force of the spring means to move the brake means and the tape tensioning rotation transmitting means out of the individual operative positions and the tape tensioning motor switch to an open position. and a reset member for inhibiting, after the controlling member is moved away from the home position, the controlling member from being returned to the home position by the spring means until the tape cassette ejecting function is subsequently selected.

With the tape tensioning device, when a tape cassette is loaded in position. the tape feeding motor is connected to the power source by way of the cassette detecting switch and the tape tensioning motor switch so that it starts its rotation. and such rotation of the motor is transmitted to the specific one reel spindle by way of the tape tensioning rotation transmitting means while the other reel spindle is inhibited from rotation by the brake means. Consequently, in case there is some slack in the tape within the tape cassette when the tape cassette is loaded in position, such tape slack is absorbed upon rotation of the specific one reel spindle.

Then, after the slack of the tape within the tape cassette is absorbed and the tape is brought into a tensioned condition, this is detected by the tension detecting means. Thereupon. the controlling member is moved away from the home position to disconnect the rotation transmitting route by the tape tensioning rotation transmitting means. to cancel the braked condition by the brake means and to switch the tape tensioning motor switch off to disconnect the tape feeding motor from the power source to stop rotation of the motor. After then, when a tape recorder function for normal operation is selected. that is, when an operation mode for playing, recording, fast feeding or rewinding is selected. the tape recorder function can be started with the tape held in a taut condition within the tape cassette.

In short, even if there is some slack in the tape within a tape cassette which is to be loaded into the tape recorder, such slack of the tape is absorbed automatically only by loading the tape cassette in position into the tape recorder without requiring any other additional or special operation.

Besides, after the tape is tensioned, the controlling member is held away from the home position against the spring means by the reset member until the tape cassette ejecting function is selected subsequently. Accordingly. even if any tape recorder function for normal operation is selected after then, the tape tensioning device will not be rendered operative inadvertently. As a matter of fact, little slack of the tape within the tape cassette will take place unless the tape cassette is removed from the tape recorder. Accordingly, if the tape tensioning device is otherwise rendered operative each time a tape recorder function for normal operation is stopped, then a useless operation of the device will take place. Such useless operation, however. is eliminated with the tape tensioning device.

The reset member may be supported for pivotal motion around a fixed axis and normally biased to a predetermined position by a spring means and have an inclined face formed thereon such that. when the controlling member is moved away from the home position.

the inclined face is slidably pushed by the controlling member to pivot the reset member against the spring means to permit such movement of the controlling member.

whereafter the reset member is returned by the spring means to the predetermined position at which the inclined face inhibits the controlling member from being returned to the home position.

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 in which like parts are denoted by like reference characters all through the drawings.

FIGS. 1 to 3 are plan views showing different stages of operation of a tape recorder in which a tape tensioning device according to the present invention is incorporated: FIG. 4 is a perspective view showing part of the tape tensioning device shown in FIGS. 1 to 3; FIG. 5 is a fragmentary perspective view showing a tape tensioning rotation transmitting means of the tape tensioning device shown in FIGS. 1 to 3; and FIGS. 6 and 7 are plan views showing different stages of operation of another tape recorder in which a tape tensioning device according to a second embodiment of the present invention is incorporated.

Referring first to FIG. 1. there is shown a tape recorder mechanism in which a tape tensioning device according to the present invention is incorporated. The tape recorder shown includes a pair of left and right reel spindles 2a and 2b mounted for rotation on a tape recorder base plate 1. A pair of reel gears 3a and 3b which serve as reel bases are provided below the reel spindles 2a and 2b, respectively. and a brake plate 4 in the form of a disk having a toothed portion 4a formed on an outer periphery thereof is provided in an overlapping relationship on the reel gear 3b below the left-hand side reel spindle 2b.

A cassette detecting switch 6 is mounted on the base plate 1 such that it may be operated by a rear face 5a of a tape cassette 5 when the tape cassette 5 is loaded in position onto the reel spindles 2a and 2b as shown in FIGS. 2 and 3. The cassette detecting switch 6 is of the normally open type and has a pair of contacts 6a and 6b for contacting with each other. A contacting member 7 is mounted at an end of the contact 6a of the cassette detecting switch 6 and normally located within a range which is to be occupied by the tape cassette 5 in the loaded position. The contacting member 7 has an inclined face 7a formed thereon as shown in FIG. 4 such that, when the tape cassette 5 is loaded in position.

the inclined face 7a is engaged and pushed by the rear face 5a of the tape cassette 5 to yieldably deflect the contact 6a of the cassette detecting switch 6 against its resilient force into contact with the other contact 6b to close the cassette detecting switch 6. The cassette detecting switch 6 is held in the closed condition until the tape cassette 5 is removed from the loaded position. The contact 6a of the cassette detecting switch 6 is electrically connected to a tape feeding motor 9 by way of a tape tensioning motor switch 8 while the other contact 6b is electrically connected to one of a pair of poles of a power source PS.

The tape tensioning motor switch 8 is of the normally closed type and has a pair of contacts 8a and 8b for contacting with each other. A contacting member 10 is mounted at an end of the contact 8a. The contact 8a is electrically connected to the contact 6a of the cassette detecting switch 6 while the other contact 8b is connected to a terminal of the tape feeding motor 9.

A motor switch 9a for normal operation is connected in parallel to the tape tensioning motor switch 8. The tape feeding motor 9 is mounted on the base plate 1 and is electrically connected at the other terminal thereof to the other pole of the power source PS. When a pivotal lever 19 which will be hereinafter described pushes the contacting member 10 on the contact 8a of the tape tensioning motor switch 8. the contact 8a is deflected against its own resilient force to move away from the other contact 8b to open the tape tensioning motor switch 8. The tape tensioning motor switch 8 is held in the open condition until the pivotal lever 19 is moved away from the contacting member 10.

A controlling member 11 is mounted for pivotal motion around a shaft lla at a location on the base plate 11 between the two reel spindles 2a and 2b. The controlling member 11 has three arms 12. 13 and 14 extending radially from a central portion thereof at which it is supported for pivotal motion. A brake pawl 15 is formed on a side face of the first arm 12 of the controlling member 11 for engagement with the toothed portion 4a of the outer periphery of the brake plate 4.

The brake pawl 15 of the controlling member 11 and the brake plate 4 cooperatively constitute a brake means 16 for inhibiting rotation of the left-hand side reel spindle 2b in FIG. 1. The controlling member 11 is normally biased in the clockwise direction in FIG. 1 by a return spring 17 to engage the brake pawl 15 thereof with the toothed portion 4a of the brake plate 4.

A small diameter gear 18 is supported for rotation on the base plate 1 adjacent the right-hand side reel spindle 2a. The small diameter gear 18 makes, upon normal operation of the tape recorder such as reproduction recording, fast feeding or rewinding, part of a normal operation rotation transmitting means for transmitting a turning force of the tape feeding motor 9 alternatively to the right- or left-hand side reel spindle 2a or Zb.

Referring to FIGS. 1 and 5. a pivotal lever or bellcrank 19 is mounted for pivotal motion around a shaft 19a on the tape recorder base plate 1 adjacent the small diameter gear 18. First and second transmitting gears 20 and 21 are supported for rotation at an end portion of one of a pair of arms of the pivotal lever 19 by means of a common shaft 22. Upon counterclockwise or clockwise pivotal motion of the pivotal lever 19 in FIG. 1, the first and second transmitting gears 20 and 21 are simultaneously moved into or out of meshing engagement with the small diameter gear 18 and righthand side reel gear 3a, respectively.A compression coil spring 23, the second transmitting gear 21, a friction sheet or disk 24 and the first transmitting gear 20 are fitted in this order from below on the shaft 22 for the first and second transmitting gears 20 and 21, thereby constituting a tape tensioning rotation transmitting means 25 for transmitting rotation from the small diameter gear 18 to the right-hand side reel gear 3a. A snap ring 26 is fitted at a top end portion of the shaft 22 for preventing the various members on the shaft 22 including the first and second transmitting gears 20 and 21 from coming off from the shaft 22.

Referring also to FIG. 4, an eccentric cam 27 is provided at a central portion of an upper or axial end face of the first transmitting gear 20. and an engaging projection 28 is provided on the upper face of the first transmitting gear 20 in an opposing, spaced relationship to and from a minimum radius portion of the eccentric cam 27. Meanwhile. the second transmitting gear 21 has a cylindrical hub portion 21a, and the friction sheet 24 and the first transmitting gear 20 are fitted around the hub portion 21 a. A rotation detecting member 29 is located abowe the first transmitting gear 20 and resiliently and frictionally fitted at an end thereof around a top end portion of the hub portion 21a of the second transsltting gear 21.The rotation detecting member 29 has a pressing pin 30 at the other pivoting end thereof Referring back to FIG. 1, an engaging recess or slot 31 is formed radially in the other arm of the pivotal lever 19. and an engaging pin 32 provided at an end of the second arm 13 of the controlling member 11 is fitted 1m the engaging recess 31. A pivot shaft 34 is provided at a location of the second arm 13 of the control ember 11 near the engaging pin 32, and a slide plate 33 is mounted for pivotal motion and also for slidfag cement on the second arm 13 of the controllasg ember 11 by means of the pivot shaft 34.

The slide plate 33 has a cam pin 35 provided at an end thereof and is normally biased in the direction toward the end thereof by a return spring 36. The cam pin 35 is disposed for sliding contact with the eccentric cam 27 of the bfst transmitting gear 20 and also for abutting engagement with the engaging projection 28 on the first transmitting gear 20. A tape tension detecting means 37 is thus constituted from the eccentric cam 27 and engaging projection 28 both on the first transmitting gear 20 as well as the rotation detecting member 29 and slide plate 33.

The third arm 14 of the controlling member 11 is located for abutting engagement at an end 14a thereof with an engaging projection 39 formed adjacent an end 38a of a reset member 38. The reset member 38 has a substantially L-shape in plan and is supported at an intermediate corner portion thereof for pivotal motion on the base plate 1 by means of a shaft 40. The engaging projection 39 of the reset member 38 has a Vor wedge-shape having a pair of inclined faces or sides 39a and 39b for slidingly engaging with the end 14a of the third arm 14 of the controlling member 11. The reset member 38 is normally biased in the counterclockwise direction in FIG. 1 by a return spring 41. The other end 38b of the reset member 38 is normally held in contact with an end 42a of an eject operating lever 42.When the controlling member 11 assumes such a home position wherein the brake pawl 15 thereon engages with the toothed portion 4a of the brake plate 4 as shown in FIG. 1, the end 14a of the third arm 14 of the controlling member 11 contacts with the inclined face 39a of the engaging projection 39 of the reset member 38. However, when the controlling member 11 is pivoted in the counterclockwise direction in FIG. 1 from the home position against the biasing force of the return spring 17 to move the brake pawl 15 thereon out of meshing engagement with the toothed portion 4a of the brake plate 4, the end 14a of the third arm 14 of the controlling member 11 is moved out of contact with the inclined face 39a and now into sliding contact with the other inclined face 39b of the engaging projection 39 of the reset member 38 as seen in FIG. 3.The controlling member 11 is thereafter held, against the biasing force of the spring 17 through the engagement of the end 14a of the third arm 14 of the controlling member 11 with the inclined face 39b of the engaging projection 39 of the reset member 38, at the pivoted position in which the brake pawl 15 remains out of engagement with the toothed portion 4a of the brake plate 4 until after the eject operating lever 42 is pushed in in the direction indicated by an arrow mark A in FIG. 1 against the biasing force of the return spring 41 to pivot the reset member 38 in the clockwise direction in FIG. 3 against the biasing force of the return spring 41 in order to remove the tape cassette 5 from the loaded position.

Thus, in the condition shown in FIG. 1 wherein the tape cassette 5 is not loaded, the cassette detecting switch 6 is in an open condition wherein the contact 6a thereof is clear of the other contact 6b due to its own resilient force. Meanwhile, the tape tensioning motor switch 8 is In a closed condition wherein the contact 8a thereof is held in contact with the other contact 8b due to its own resilient force.

Further, the controlling member 11 is held at its home position under the biasing force of the spring 17.

Accordingly, the tape feeding motor 9 remains in a deenergized condition and hence in a stopped condition.

Meanwhile, the brake pawl 15 is held in engagement with the toothed portion 4a of the brake plate 4 to inhibit rotation of the left-hand side reel spindle 2b, and the first and second transmitting gears 20 and 21 are also held in engagement with the small diameter gear 18 and right-hand side reel gear 3a, respectively. Further, the end 14a of the third arm 14 of the controlling member 11 is held in contact with the inclined face 39a of the engaging projection 39 of the reset member 38 while the other end 38b of the reset member 38 is held in contact with the end 42a of the eject operating lever 42.

It is assumed now that a tape cassette 5 wherein the magnetic tape 5b has some slack is loaded in position onto the reel spindles 2a and 2b. Upon such loading, the rear face 5a of the tape cassette 5 is engaged with the inclined face 7a of the contacting member 7 of the cassette detecting switch 6 and pushes the contacting member 7 to move upwardly in FIG. 1.

Consequently, the contact 6a of the cassette detecting switch 6 on which the contacting member 7 is mounted is resiliently deflected upwardly in FIG. 1 against the resilient force thereof so that it is brought into contact with the other contact 6b to close, and thereafter hold the closed condition of, the cassette detecting switch 6 as shown in FIG. 2. Consequently.

the tape feeding motor 9 is connected to the power source PS and energized to start its rotation, and such rotation of the motor 9 is transmitted from the small diameter gear 18 to the right-hand side reel spindle 2a by way of the first and second transmitting gears 20 and 21 and reel gear 3a.

When the tape feeding motor 9 rotates as described above, the second transmitting gear 21 is rotated in the clockwise direction in FIG. 2.

Consequently, the rotation detecting member 29 is urged to pivot in the clockwise direction by the second transmitting gear 21 so that it presses at the pressing pin 30 thereof against a side of the slide plate 33 to urge the slide plate 33 in the counterclockwise direction in FIG. 2. Consequently, the cam pin 35 on the slide plate 33 is pressed against and hence slides on a circumferential-face of the eccentric cam 27. As a result, the slide plate 33 is rocked around the pivot shaft 34 while the eccentric cam 27 is rotated in the clockwise direction together with the first transmitting gear 20.

When the right-hand side reel spindle 2a is rotated as described above, the left-hand side reel spindle 2b is held from rotation by the brake means 16, and consequently, the magnetic tape 5b within the tape cassette 5a is taken up by a distance corresponding to the slack.

After the original slack is absorbed to put the tape 5b in the cassette 5 in a tensioned condition, the right-hand side reel spindle 2a and hence the second transmitting gear 21 are stopped by way of the tape 5b because the left-hand side reel spindle 2b is stopped from rotation by the brake means 16. Consequently, the rotation detecting member 29 is no more urged in the clockwise direction, and the slide plate 33 is no more pressed at the cam pin 35 thereof against the eccentric cam 27.Meanwhile, since the first transmitting gear 20 still continues its rotation while yielding a slip at the friction sheet 24 (FIG. 6) between the first and second transmitting gears 20 and 21, the cam pin 35 on the slide plate 33 is displaced by the eccentric cam 27 finally to a position on a locus of rotation of the engaging projection 28 by a maximum radius portion of the eccentric cam 27 as seen in FIG. 3.

Then, when the first transmitting gear 20 is rotated further, the cam pin 35 is soon engaged by the engaging projection 28 on the first transmitting gear 20 and turning force of the first transmitting gear 20 is transmitted to the slide plate 33 by way of the engaging projection 28 and the cam pin 35 to move the slide plate 33 in the direction opposite to the direction of the biasing force of the spring 36. Thereupon. the slide plate 33 pivots the controlling member 11 in the counterclockwise direction in FIG. 3 against the biasing force of the return spring 17. and the controlling member 11 in turn pivots the pivotal lever 19 in the clockwise direction in FIG. 3.As a result, the first and second transmitting gears 20 and 21 are moved away from the small diameter gear 18 and right-hand side reel gear 3a, respectively, thereby to disconnect the rotation transmitting route from the tape feeding motor 9 to the right-hand side reel spindle 2a by the tape tensioning rotation transmitting means 25. Further, upon clockwise pivotal motion of the pivotal lever 19, the contacting member 10 on the contact 8a of the tape tensioning motor switch 8 is pushed by the pivotal lever 19 to yieldably deflect the contact 8a against its resilient force to move out of contact with the other contact 8b to open the tape tensioning rotor switch 8.

Consequently, the tape feeding motor 9 is disconnected from the power source PS and thus stopped. On the other hand, upon counterclockwise pivotal motion of the controlling member 11, the brake pawl 15 is spaced away from the toothed portion 4a of the brake plate 4 to cancel the inhibition of rotation of the left-hand side reel spindle 2b. Further. upon counterclockwise pivotal motion of the controlling member 11, the end 14a of the third arm 14 thereof first pushes at the inclined face 39a of the engaging projection 39 of the reset member 38 to pivot the reset member 38 in the clockwise direction against the biasing force of the return spring 41.

Then, when the end 14a of the third ari 14 is disengaged from the inclined face 39a and now engaged with the other inclined face 39b of the engaging projection 39, the reset member 38 is pivoted back in the counterclockwise direction in FIG. 3 by the biasing force of the return spring 41. Consequently, the controlling member 11 is thereafter held at the counterclockwise pivoted position by the reset member 38 as seen in FIG. 3. If a desired tape recorder function such as reproduction, recording or fast feeding is selected by a suitable means not shown, the motor switch 9a for normal operation is closed to start the tape feeding motor 9. Consequently, desired operation can be started while the tape 5b within the tape cassette 5 has no slack thereon.

Then, if a- stopping function is selected to stop operation of the tape recorder and then the eject operating lever 42 is pushed in in the direction indicated by the arrow mark A to a position shown in phantom in FIG. 3 in order to remove the tape cassette 5, the end 42a of the eject operating lever 42 pushes the end 38b of the reset member 38 to pivot the reset member 38 in the clockwise direction to such a position as shown in phantom in FIG. 3 against the biasing force of the return spring 41. Thereupon, the inclined face 39b of the engaging projection 39 of the reset member 39 is moved away from the end 14a of the third arm 14 of the controlling member 11 to permit the controlling member 11 to be pivoted in the clockwise direction until the associated elements are returned to their home positions shown in FIG. 1. thereby preparing for subsequent loading of another tape cassette.

Referring now to FIGS. 6 and 7, there is shown a tape tensioning device for a tape recorder according to a second embodiment of the present invention. Since the tape tensioning device of the present embodiment has somewhat similar construction to that of the tape tensioning device of the preceding embodiment, like parts or elements are denoted by like reference characters to those of the preceding embodiment.

The tape tensioning device of the present embodiment is different in construction of the tape tension detecting means thereof from the tape tensioning device of the preceding embodiment. In particular. the tape tension detecting means 37a in the second embodiment is constituted such that it detects movement of the left-hand side reel spindle 2b to disconnect the rotation transmitting route from the tape feeding motor 9 and deenergize the tape feeding motor 9 to stop its rotation. A shaft 43 for the left-hand side reel spindle 2b is mounted on the base plate 1 for limited movement in a plane thereof (within a range of movement of a reel hub in the tape cassette 5).The shaft 43 for the left-hand side reel spindle 2b is mounted on a pivotal lever 45 which in turn is supported for pivotal motion around a shaft 44 on the base plate 1 such that the pivotal lever 45 may be pivoted around the shaft 44 when the shaft 43 is moved. The pivotal lever 45 is normally biased in the counterclockwise direction in FIG. 6 by a return spring 46. The pivotal lever 45 is normally held in abutting engagement at an end 45a thereof with an end 48a of a first arm 48 of a pivotal plate 47. The pivotal plate 47 is supported for pivotal motion around a shaft 49 on the base plate 1. The pivotal plate 47 has first. second and third arms 48. 50 and 51 extending radially from a portion thereof at which it is supported for pivotal motion around the shaft 49.An end 50a of the second arm 50 can be positioned for engagement with the engaging projection 28 of the first transmitting gear 20. Meanwhile, an end 51a of the third arm 51 of the pivotal plate 47 is positioned for abutting engagement with an inclined face llb of the controlling member 11. The pivotal plate 47 is normally biased in the clockwise direction by a return spring 52. The pivotal lever 19 is supported for pivotal motion around a shaft l9a on which the small diameter gear 18 is coaxially mounted, and the small diameter gear 18 is normally held in meshing engagement with the first transmitting gear 20.

In the tape tensioning device having such construction as described above. after the magnetic tape 5b in the tape cassette 5 is tensioned. the left-hand side reel spindle 2b is displaced from a position shown in a solid line to another position shown in phantom in FIG. 6 by the tension of the magnetic tape 5b whereupon the pivotal lever 45 is pivoted in the clockwise direction around the shaft 44 from a position shown in solid lines to another position shown in phantom against the biasing force of the return spring 46. Upon such pivotal motion, the pivotal plate 47 is pushed to pivot in the counterclockwise direction around the shaft 49 from a position shown in solid lines to another position shown in phantom in FIG. 6 against the biasing force of the return spring 52.Upon such pivotal motion of the pivotal plate 47, the end 50a of the second arm 50 thereof is moved to a position on a locus of movement of the engaging projection 28 on the first transmitting gear 20 which is being rotated by the tape feeding motor 9. Consequently. the engaging projection 28 is soon engaged with and pushes the end 50a of the second arm 50 of the pivotal plate 47 to pivot the pivotal plate 47 further in the counterclockwise direction under the turning force of the first transmitting gear 20. Upon such counterclockwise pivotal motion of the pivotal plate 47. the end 51a of the third arm 51 thereof pushes at the inclined face llb of the controlling member 11.

Consequently, the controlling member 11 is pivoted in the counterclockwise direction against the biasing force of the return spring 17 to cancel the inhibition of rotation of the left-hand side reel spindle 2b. Upon such counterclockwise pivotal motion of the controlling member 11. the pivotal lever 19 is pivoted in the clockwise direction, and thereupon, the tape tensioning motor switch 8 is opened and the second transmitting gear 21 is moved out of meshing contact with the righthand side reel gear 3a.

Claims (3)

ClAIMS:

1. A tape tensioning device for a tape recorder of the type wherein a tape feeding motor is connected to a power source by way of a motor driving circuit for normal operation in response to selection of a tape recorder function with a tape cassette loaded in position on a pair of reel spindles of said tape recorder and rotation of said tape feeding motor is transmitted alternatively to either one of said reel spindles by way of a rotation transmitting means for normal operation to cause said tape recorder to operate in an operation mode corresponding to the selected tape recorder function, and the tape cassette is removed from said reel spindles in response to selection of a tape cassette ejecting function, comprising:: a cassette detecting switch of the normally open type which is closed and held closed by the tape cassette loaded in position on said reel spindles; a tensioning motor switch connected in series to said cassette detecting switch for connecting said tape feeding motor to said power source; a tape tensioning rotation transmitting means for transmitting turning force of said tape feeding motor to a specific one of said reel spindles: a brake means for inhibiting rotation of the other specific reel spindle: a controlling member having a home position at which said ~brake means and said tensioning rotation transmitting means assume individual operative positions and said tape tensioning motor switch assumes a closed position; a spring means for resiliently biasing said controlling iember to the home position:: a tension detecting means for either detecting stopping of the specific one reel spindle or detecting an increase of tension of the tape between said reel spindles tc wove said controlling member away from the home position against the biasing force of said spring means to sove said brake means and said tape tensioning rotation transmitting means out of the individual operative positions and said tape tensioning motor switch to an open position; and reset member for inhibiting. after said controlling member is moved away from the home position.

said contrelling member from being returned to the home position by said spring means until the tape cassette ejecting function is subsequently selected.

2. A tape tensioning device as claimed in claim 1, wherein said reset member is supported for pivotal motion around a fixed axis and normally biased to a predetermined position by a spring means and has an inclined face formed thereon such that, when said controlling member is moved away from the home position, said inclined face is slidably pushed by said controlling member to pivot said reset member against said spring means to permit such movement af said controlling member, whereafter said reset member is returned by said spring means to the predetermined position at which said inclined face inhibits said controlling member from being returned to the home position.

3. A tape tensioning device as claimed in claim 2 and substantially as hereinbefore described with reference to and as shown in the accompanying drawings.