JPS5824855B2 - How to make a difference - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tape recorder in which a pair of reel axes are respectively driven by a pair of reel motors that are directly connected to the reel axes, and when a stop command is issued, these reel motors are driven. The present invention relates to a braking device that brakes the reel shaft of the vehicle.

Conventionally, in this type of tape recorder, an electromagnetic brake and a mechanical brake are used to stop the supply reel motor and take-up reel motor, which are rotating at high speed, when the stop button is pressed in the fast forward or rewind state. The mechanical brake is activated after the electromagnetic brake is used to decelerate the engine to a predetermined rotational speed or less.

This is because if the brake shoes are pressed against the brake drum during high-speed rotation of the reel motor, such as during fast forwarding or rewinding, the wear between the two will be too thick, so this kind of wear can be reduced to a certain extent. This is to make it happen.

Therefore, in this case, when the stop button is pressed, the electromagnetic brake is activated to decelerate the supply and rewind reel motors, respectively, and a frequency signal corresponding to the decelerated rotational speed of the motors is obtained from the frequency generator.

Then, the frequency change around the set center frequency of this frequency signal is converted into a DC voltage by the FM demodulator, and this DC voltage is compared with a reference voltage, so that the rotational speed of the motor becomes below a predetermined value. The mechanical brake operates based on this detection result.

Therefore, it is necessary to perform analog processing on the frequency signal, and there are problems in particular with the stability of the FM demodulator, and there are also problems with the phase rotation of the low-pass filter to remove the carrier component from the demodulated output of the FM demodulator. Therefore, there was a drawback that the power generation frequency of the frequency generator had to be made sufficiently high.

For this reason, it has been difficult to integrate the circuit, resulting in low reliability and high cost.

The present invention was invented to correct the above-mentioned defects, and by skillfully combining an electromagnetic brake and a mechanical brake, braking can be performed reliably. There is no risk of wear, the structure is simple, the braking operation can be electrically performed reliably, and the pulse interval of the pulse train generated in response to the rotational speed of the reel shaft does not need to be particularly small. (Moreover, it is possible to provide a circuit that is easy to integrate, has high reliability, and can reduce costs.

In a preferred embodiment of the present invention, the predetermined value of the pulse interval when the inversion signal generation circuit generates the inversion signal is determined by the time constant circuit, and this predetermined value can be varied as necessary. There is.

With this configuration, the predetermined value of the rotational speed to be detected can be arbitrarily selected.

Next, an embodiment in which the present invention is applied to a reel motor control device in a tape recorder will be described with reference to the drawings. In the block diagram of the control circuit shown in FIG. The play switch element 7 to provide is a flip-flop 1
10 is connected to the set terminal S, and the flip-flop 1
The output of Q&'' is supplied to the input terminal 1 of the gate 390.

A fast-forward switch element 9 for providing a pulse for fast-forward operation is connected to the set terminal S of the flip-flop 120, and the output Q of the flip-flop 12 is supplied to the input terminal 2 of the NOR gate 390 and the set terminal S of the flip-flop 260, respectively. There is.

A rewind switch element 10 providing a rewind operation pulse is connected to the set terminal S of the flip-flop 130, and the output Q of the flip-flop 13 is supplied to the input terminal 3 of the NOR gate 39 and the set terminal S of the flip-flop 27. It looks like this.

Note that the output side of the NOR gate 39 is connected to the set terminals S of the flip-flops 19 and 21, respectively.

The output side of the AND gate 30 is connected to the reset terminal R of the flip-flop 11, the output side of the AND gate 31 is connected to the reset terminal R of the flip-flop 12, and the output side of the AND gate 32 is connected to the reset terminal R of the flip-flop 13. are connected to each other.

One input terminal of each of these AND gates 30.degree.
A stop switch element 8 that provides a stop pulse is connected to each of the stop switch elements 8.

The other input terminal of AND gate 30 has AND gate 3
3 is connected to one input terminal of the AND gate 33, as well as the other input terminal of the AND gate 32.
The output Q of the flip-flop 12 is supplied.

Also, the other input terminal of the AND gate 33 has a flip-flop 1 connected thereto as well as the other input terminal of the AND gate 31.
3 output q is supplied.

Frequency generators 14 and 15 are attached to the supply reel motor 40 and take-up reel motor 41 shown in FIG. 2, respectively, and the frequency signals of these frequency generators 14 and 15 are supplied to waveform shaping circuits 16 and 17, respectively. It has become so.

The outputs of these waveform shaping circuits 16 and 17 are supplied to the trigger terminals of retrigger type monostable multivibrators 18 and 20, respectively, and these multivibrators synchronize the period of the input frequency and the reference time. A signal is generated when the period of the input frequency becomes longer than the reference time.

The output Q of each of the retrigger type monostable multivibrators 18 and 20 is supplied to one input terminal of each of OR gates 34 and 36, respectively.

The other input terminals of the OR gates 34 and 36 are connected to positive trigger type monostable multivibrators 22 whose trigger inputs are the outputs q of the flip-flops 19 and 21, respectively.
and 23 are supplied, and the output sides of the OR gates 34 and 36 are connected to the reset terminals R of the edge-triggered flip-flops 24 and 25, respectively.

The outputs Q of the flip-flops 19 and 21 are supplied to the set terminals S of the flip-flops 24 and 25, and to one input terminal of the OR gates 35 and 37, respectively. The outputs Q of the flip-flops 24 and 25 are supplied to the other input terminals of the flip-flops 24 and 25, respectively.

The output side of the OR gate 35 is connected to one input terminal of the OR gate 38, and the output side of the OR gate 37 is connected to the OR gate 38.
The output side of the OR gate 38 is connected to the reset terminal R of each of the flip-flops 26 and 27, respectively.

In FIG. 2 showing the relationship between the control circuit and the reel motors 40 and 41, drive amplifiers 42 and 43 having signal terminals 1 to 6 are connected to the supply reel motor 40 and the take-up reel motor 41, respectively. The motors are driven to their respective operating states by drive amplifiers 42 and 43.

In each of the signal terminals 1 to 6 of the drive amplifiers 42 and 43, 1 is a play signal terminal, 2 is a fast forward signal terminal, 3 is a rewind signal terminal, 4 and 5 are husband electromagnetic brake signal terminals,
6 is an on/off signal terminal, and 1 is connected to each signal terminal.
or O signals are supplied to control the respective operations.

Mechanical brakes 44 and 45 include plunger mechanisms 48 and 49 that apply braking force to brake drums 46 and 47, respectively, which are fixed to rotating shafts 56 and 57 of supply and take-up reel motors 40 and 41, respectively, and plunger mechanisms 48 and 49 that apply braking force to brake drums 46 and 47, respectively, and and energizing means for turning on and off energization to the jar mechanism.

Frequency generators 14 and 15 are attached to the motors 40 and 41, respectively, to generate frequency signals proportional to their rotational speeds.The respective signal terminals shown in FIG. The respective outputs of the circuits are adapted to be supplied.

That is, the play signal terminal 1 of each drive amplifier 42 and 43 receives the output Q of the flip-flop 110, the fast-forward signal terminal 2 receives the output Q of the flip-flop 12, and the rewind signal terminal 3 receives the output Q of the flip-flop 13. The output Q of
In addition, a flip-flop 26 is connected to the electromagnetic brake signal terminal 4.
The output Q of the flip-flop 27 is applied to the electromagnetic brake signal terminal 5, and the output of the OR gate 38 is applied to the on/off signal terminal 6 and the mechanical brake signal terminals 6 of the mechanical brakes 44 and 45, respectively. It is now being supplied.

In the reel motor control device shown in FIGS. 1 and 2 constructed as described above, when the play switch element 7 is short-circuited, a negative start pulse is applied to the set terminal S of the flip-flop 110, and this flip-flop 11 is triggered. , so flip-flop 11 is set and its output Q is therefore inverted from 0 to 1.

When the output Q of flip-flop 11 is inverted from 0 to 1, its output triggers flip-flops 19 and 21, respectively, as a negative trigger pulse via NOR gate 39.

Therefore, since the flip-flops 19 and 21 are set respectively, their output Q is inverted from O to 1 and becomes OR game)3
5.370 inputs respectively.

These level 1 signals are passed through OR gates 35 and 37, respectively, and also via OR gate 38, to the on/off signal terminals 6 of drive amplifiers 42 and 430, respectively, and to the mechanical brake signal terminals of mechanical brakes 44 and 45, respectively. 6, respectively, so that the drive amplifiers 42 .
43 are each turned on, and the mechanical brake 4
4.45 are also turned on, and the brake drums 46,
470 locks are released respectively.

On the other hand, since the level 1 signal of the output Q of the flip-flop 11 is supplied to the play signal terminal 1 of each of the drive amplifiers 42 and 43, each of the drive amplifiers 42 and 43 enters the play operation state.

Therefore, the supply and take-up reel motors 40 and 41 perform a play operation, so that the take-up reel motor 41 is connected to the take-up reel 6.
1 is the direction in which the tape 62 is wound (i.e., counterclockwise in FIG. 2)
The supply reel motor 40 is given a relatively small rotational driving force in the direction in which the supply reel 60 winds the tape 62 (ie, clockwise in FIG. 2).

This latter driving force is for applying pack tension to the tape.

Therefore, the tape is pulled from both sides, but in this case the winding force by the take-up reel 61 is greater than the winding force by the supply reel 60.

Therefore, in the fast forward operation state, the tape 62 is wound around the winding wheel 61 due to the difference in these winding forces.
In the play mode, the tape is transported at a constant speed by a capstan and pinch rollers (none of which are shown) and is wound onto a take-up reel.

When the supply and take-up reel motors 40 and 41 are driven to rotate, the frequency generators 14 and 15 generate frequency signals proportional to the number of rotations of the husband's motors, and these frequency signals are transmitted to the waveform shaping circuit 16. The waveform was shaped at step 17,
This results in a positive pulse train whose pulse interval changes in proportion to the frequency change, which triggers the retriggerable monostable multivibrators 18, 20, respectively.

The retrigger type monostable multivibrators 18 and 20 are
A monostable multivibrator that continues to trigger and maintains a metastable state when a trigger pulse is applied again within a metastable period determined by the time constant,
The metastable period (hereinafter referred to as the set value).

) is set longer than the pulse interval of the pulse train in a predetermined running state.

Therefore, while the tape is running in a predetermined running state, the retrigger type monostable multivibrators 18 and 20 are successively triggered while the level of these outputs Q is 1, so these outputs Q are Keep that level at 1.

Note that the above set value can generally be determined by a time constant circuit, but if this set value is made variable as necessary, the predetermined value of the rotational speed to be detected can be arbitrarily selected. .

In this state, when the stop switch element 8 is short-circuited and a negative trigger pulse is applied to the reset terminals R of the flip-flops 19 and 21, the flip-flops 19 and 21 are reset, so their outputs Q change from 1 to 0, respectively. Invert.

In this way, the output Q of each flip-flop 19 and 210 is
When 1 and 0 are respectively reversed, the flip-flops 24,
25 are set respectively, so the flip-flop 242
The respective outputs Q of 5 are inverted from 0 to 1, respectively, so that the output side of the OR gate 38 continues to hold the level 1.

On the other hand, since the stop pulse is applied to the reset terminal R of the flip-flop 11 via the AND gate 30,
Flip-flop 11 is reset.

For this reason, the output Q of the 7-lip flop 11 is inverted from 1 to 0, so that the drive amplifiers 42 and 43 are switched from the play operation state to the play release state.

As a result, the rotation speed of the motor decreases and the pulse interval of the pulse train becomes longer than the set value, so the output Q of each of the retrigger type multivibrators 18 and 20 changes from 1 to the set value determined by these time constants. 0, and for this reason these outputs trigger edge-triggered flip-flops 24 and 25 via gates 34 and 36, respectively.

Therefore, the output Q of each of the edge trigger type flip-flops 24 and 250 is inverted from 1 to 0, and the level on the output side of the OR gate 38 becomes 0, so that the drive amplifiers 42 and 43 are turned off and the mechanical brakes 44 and 45 are turned off. The brake drums 46 and 47 are turned off and brake force is applied to the brake drums 46 and 47, thereby stopping the rotation of the motors 40 and 410, respectively.

3A to 3G are waveform diagrams of each part shown in FIG. 1 for explaining the operation from the play start state to the stop state (in other words, the normal play state). Figure 3A shows the start pulse, Figure 3B shows the stop pulse, and Figure 3C shows the flip-flops 19 and 2.
10, and FIG. 3D shows the input pulse train of the retrigger type monostable multivibrator 18, 20, and FIG. 3E shows the input pulse train of the retrigger type monostable multivibrator 18.
, 20, and FIG. 3F shows the output Q of flip-flop 2.
4,250 output Q and FIG. 3G shows the output side of OR gate 38 in their respective signal waveforms.

The positive trigger type monostable multivibrators 22 and 23 prevent the motor rotation from stopping because the level on the output side of the OR gate 38 does not reach O when a stop pulse is applied immediately after the start pulse is applied. are doing.

That is, when the stop pulse is applied immediately after the start pulse is applied, the outputs of the frequency generators 14 and 15 do not yet have a value sufficient for the waveform shaping circuits 16 and 17 to form a pulse train. The retrigger type monostable multivibrator 18, 20 has not yet been supplied with a pulse train.

Therefore, flip-flop 2425 is or game) 34.3
These flip-flops are in the set state since the trigger pulses applied through Q 6 have not yet been applied, so their outputs Q remain at level 1 immediately after the application of the stop pulses, and therefore the motor 4041 is At this rate, the rotation will not stop.

The positive trigger type monostable multivibrators 22 and 23 are able to control the motors 40 and 4 even when a stop pulse is applied in this way.
1 from not stopping, and when a stop pulse is applied, the flip-flops 19 and 2
The output q of each of the 10 is inverted from 0 to 1.

For this purpose, a positive trigger type monostable multivibrator 2
2 and 23 are triggered respectively, so their output Q is 0.
However, these positive trigger type monostable multivibrators 22 and 23 reverse from 1 to 0 again after a certain period of time determined by their time constants.

The inversion of this output Q from 1 to O is an or game) 34.36
The husband and wife then trigger the flip-flops 24 and 25, respectively.

Therefore, the flip-flops 24 and 25 are reset and their outputs Q are inverted from 1 to 0, respectively, so that the motor 4
0 and 41 will be stopped respectively.

(The time from when the stop pulse is applied until the motor stops rotating is a plus) It is determined by the time constant of the IJ type monostable multivibrator 22, 230, so if this time constant is made very small, for example a few milliseconds, , can be ignored compared to the time from the start to the stop of play.

4A to 4G are waveform diagrams of various parts for explaining the operation of the above-mentioned positive trigger type monostable multivibrator 22, 23, in which FIG. 4A shows the start pulse, and FIG. 4B shows the stop pulse. 4C shows the outputs Q of the flip-flops 19 and 21, FIG. 4D shows the outputs Q of the re-triggered monostable multivibrators 18 and 20, and FIG. 4E shows the outputs Q of the plus-triggered monostable multivibrator. 22 and 23, FIG. 4F shows the output Q of the flip-flop 24, 25, and FIG. 4G shows the output of the OR gate 38 in their respective signal waveforms.

Next, by shorting the fast-forward switch element 9 and applying a negative trigger pulse to the set input terminal S of the flip-flop 120, this flip-flop is triggered and set, so that its output Q is inverted from O to 1.

When the output Q of the flip-flop 12 is inverted from 0 to 1 in this way, the NOR gate 39, the flip-flop 19,
21, drive amplifiers 42, 4 through OR gates 35, 37 and 38 in the same manner as in the play start.
3 are turned on, and the mechanical brakes 44 and 45 are turned on, so the brake drum 4
6.47 unlocked.

On the other hand, since the level 1 signal of the output Q of the flip-flop 12 is supplied to the fast-forward signal terminal 2 of the drive amplifiers 42 and 430, respectively, the drive amplifiers 42 and 43 enter the fast-forward operation state.

Thus, the supply and take-up reel motors 40 and 41 are respectively driven in a fast forward operating condition, and the tape therefore runs in a fast forward condition.

Stop switch element 8 is activated while the tape is running in fast forward mode.
When a stop pulse is applied by short-circuiting, the flip-flops 19 and 21 are reset, respectively, as in the case from the play state to the stop state, and for this purpose, the edge trigger type flip-flops 24 and 25 are set, respectively. Ru.

The stop pulse is also applied to the flip-flop 12 via the AND gate 31, so that this flip-flop is reset and its output Q is inverted from 1 to 0, which causes the drive amplifiers 42, 430 to be in the fast-forward operating state. are turned off respectively.

On the other hand, when the output Q of the flip-flop 12 is inverted from 1 to 0, the flip-flop 28 is set, so the output Q of the flip-flop 26 is inverted from 0 to 1.

Therefore, since electromagnetic brake signals are applied to the drive amplifiers 42 and 430 and the electromagnetic brake signal terminal 4, the take-up reel motor 41 is given a rotational driving force in the direction opposite to the rotational direction in the fast forward running state.

At the same time, the supply reel motor 40 is given a rotational driving force in the same direction as in the fast-forward state (ie, in the direction in which the supply reel winds the tape) and greater than in the fast-forward state.

Therefore, the tape winding force by the take-up reel 61 decreases rapidly, and the tape winding force by the supply reel 60 rapidly increases, so that the fast-forwarding speed of the tape decreases rapidly.

In other words, the feed and take-up motors 40 and 410
Since the rotational speed decreases, the pulse interval of the input pulse train of each of the retriggerable monostable multivibrators 18 and 20 becomes longer than the set value, so that the output of each of the retriggered monostable multivibrators 18 and 20 increases. Q is 1
to O.

When the output Q is inverted from 1 to 0 in this way, the flip-flops 24 and 25 to which these outputs Q are applied via the OR gates 34 and 36, respectively, enter a reset state.

Therefore, the output Q of each of flip-flops 24 and 25 is 1.
Since the output side of the OR gate 38 is inverted from 1 to 0, the output side of the OR gate 38 is inverted from 1 to 0.

When the output of the OR gate 38 is inverted from 1 to 0, the flip-flop 26 is reset, so its output Q is inverted from 1 to 0.

Therefore, the electromagnetic brake signal terminals 4 of each of the drive amplifiers 42 and 43 are turned off, so that the electromagnetic brake is released.

Further, due to the above-mentioned reversal of the flip-flop 26, the drive amplifiers 42 and 43 are turned off, so the mechanical brakes 44 and 45 are turned off, and braking force is applied to the brake drums 46 and 47, respectively. The rotations of and 41 are stopped.

5A to 5G are waveform diagrams of each part for explaining the operation from the start of fast forwarding to the stop state, in which FIG. 5A shows the fast forwarding start pulse, and FIG. 5B
5C shows the output Q of the flip-flop 12, FIG. 5D shows the input pulse trains of the retrigger type monostable multivibrators 18 and 20, and FIG. 5E shows the retrigger type monostable multivibrators 18 and 20, respectively. The output Q of the stable multi-by-breaks 18 and 20, FIG. 5F shows the output Q of the flip-flop 26, and FIG. 5G shows the output side of the OR gate 38 in their respective signal waveforms.

Furthermore, when the rewinding switch element 10 is short-circuited to enter the rewinding operation state, the flip-flop 13 is set.
Its output Q is inverted from 0 to 1.

The above-mentioned inversion of the output Q of the flip-flop 13 from O to 1 is performed by driving the drive amplifiers 42 and 43 via the NOR gate 39, the flip-flop 19.21, the OR gates 35 and 37, and the OR gate 38, respectively, in the same manner as at the start of play as described above. At the same time, mechanical brake 4 is turned on.
Turn on brake drums 46 and 4γ, respectively.
Unlock the lock.

On the other hand, the level 1 signal of the output Q of the flip-flop 13 is supplied to the rewind signal terminal 3 of the drive amplifiers 42 and 430, respectively, so that the drive amplifiers 42 and 43 are in the rewind operation state.

The supply and take-up reel motors 40 and 41 are therefore driven in a rewind operation so that the tape runs in a rewind condition.

Stop switch element 8 is activated while the tape is running in the rewound state.
Since the flip-flops 19 and 21 are each reset, the edge trigger type flip-flops 24 and 25 are set, as in the case from the start of play to the stop state as described above.

Furthermore, the flip-flop 13 is reset by the stop pulse applied via the AND gate 32, and its output Q is inverted from 1 to 0.
30 rewind operations are respectively turned off.

On the other hand, when the output Q of the flip-flop 13 is inverted from 1 to 0, the flip-flop 27 is set, so the output Q of the flip-flop 27 is inverted from 0 to 1.

For this reason, the electromagnetic brake signal terminals 5 of the drive amplifiers 42 and 43 are respectively turned off, so that the supply reel motor 40 is given one rotation driving force in the opposite direction to the rotation direction in the rewinding state.

At the same time, the take-up reel motor 41 is given a rotational driving force in the same direction as in the rewinding state (ie, the direction in which the take-up reel winds the tape) and larger than that in the rewinding state.

Therefore, the tape winding force by the supply wheel 60 rapidly decreases, and the tape winding force by the take-up rule 61 rapidly increases, so that the tape rewinding speed rapidly decreases. .

In other words, since the rotational speed of the supply and take-up reel motors 40, 41 decreases, the pulse interval of the input pulse train of each retrigger type monostable multivibrator 18.200 becomes longer than the set value, and therefore The output Q of each trigger type monostable multivibrator 18 and 200 is from 1 to O.
to be reversed.

This inversion of the output Q from 1 to O resets the flip-flops 24, 25 to which the output Q is applied via ORGs 34 and 36.

Therefore, the outputs Q of the flip-flops 24 and 25 are inverted from 1 to O, respectively, so the output side of the OR gate 38 is inverted from 1 to O.
to be reversed.

When the output side of the OR gate 38 is inverted from 1 to 0, the flip-flop 27 is reset and its output Q is inverted from 1 to 0.

Therefore, the electromagnetic brake signal terminal 5 of each of the drive amplifiers 42 and 430 is turned off, the electromagnetic brake is released, and the drive amplifiers 42 and 43 are each controlled to the off state.

At the same time, the mechanical brakes 44, 45 are turned off, so the brake drums 46, 47 are locked, respectively, and the motors 40, 410 stop rotating.

The signal waveforms of each part from the start of rewinding to the stop state are the 5th A from the start of fast forwarding to the stop state.
It is similar to FIGS. 5-5G.

The present invention uses both an electromagnetic brake and a mechanical brake as described above, and first decelerates with the electromagnetic brake to bring the rotation speed below a predetermined speed, and then operates the mechanical brake, so that the four braking operations can be performed reliably. Moreover, there is no risk of significant wear on the brake shoes, unlike when a mechanical brake is applied during high-speed rotation of the reel motor.

The first bistable circuit is set to the first state by a stop command from the tape recorder's fast-forwarding state, and is inverted to the second state when the inversion signal generation circuit is inverted to the second state, and the tape recorder's winding A second bistable circuit is provided which is set to the first state by a stop command from the return state and is inverted to the second state when the inversion signal generation circuit is inverted to the second state, and the first and second bistable circuits are set to the first state. Since the output terminal of the bistable circuit is connected to the motor drive circuit, the direction in which the rotation of the reel shaft is reversed is determined regardless of whether the tape is running in fast forward mode or in rewind mode before the stop command is given. It is possible to reliably supply a drive signal to the motor 1 drive circuit for the electromagnetic brake that provides the 1 drive force.

Therefore, there is no need to detect the rotational direction of the reel shaft with a mechanical detection mechanism (it can be detected electrically), and therefore, it is possible to provide a device with a simple configuration and reliable operation.

Furthermore, since it is possible to detect when the rotational speed has fallen below a predetermined value by simply digitally processing a pulse train having a pulse interval corresponding to the rotational speed of the reel shaft, there is no need to make the pulse interval of the pulse train particularly small. (Also, it is easy to integrate into a circuit, has high reliability, and can reduce costs.)

[Brief explanation of the drawing]

The drawings show an embodiment in which the present invention is applied to a reel motor control device in a tape recorder, in which Fig. 1 is a block diagram of the control circuit, and Fig. 2 shows the relationship between the control circuit and the reel motor. Figure 3 is a waveform diagram of each part shown in Figure 1 in the normal play operation state, Figure 4 is a waveform diagram of each part shown in Figure 1 when switching to the strike state immediately after the start of play, and Figure 5 is a waveform diagram of each part shown in Figure 1 in the fast forward operation state. Reference numerals 14 and 15 are frequency generators, 18 and 20 are retrigger type monostable multivibrators, and 22 and 23 are positive trigger type monostable multivibrators. vibrator, 24.25 is an edge-triggered flip-flop, 26 is a flip-flop (first bistable circuit), 27 is a flip-flop (second bistable circuit), 42.43 is 1 drive amplifier, 44 and 45 are mechanical It's the brakes.

Claims (1)

[Scope of Claims] 1 (a) a pair of reel motors each directly connected to a pair of reel shafts of a tape recorder; (b) a motor drive circuit that drives these pair of reel motors independently of each other; (e) a mechanical brake mechanism provided in relation to the reel shaft; (d) actuating means such as a plunger for actuating the mechanical brake mechanism; (e) having a pulse interval corresponding to the rotational speed of the reel shaft. Rotation speed detection comprising pulse generation means for generating a pulse train, and an inversion signal generation circuit that maintains a first state when the pulse interval is below a predetermined value and inverts to a second state when the pulse interval exceeds a predetermined value. Mechanism, g) The first state is set to the first state by a stop command from the fast forward state of the tape recorder, and is reversed to the second state when the reversal signal generation circuit is reversed to the second state.
(g) a bistable circuit that is set to the first state by a stop command from the rewinding state of the tape recorder, and that is inverted to the second state when the inversion signal generation circuit is inverted to the second state; two bistable circuits, the output terminals of the first and second bistable circuits are connected to the motor drive circuit, and the first or second bistable circuit is in a first state. When it is in
An electromagnetic brake drive signal that provides a driving force to reverse the rotation of the reel shaft is supplied to the motor drive circuit, and the rotation of the reel shaft is decelerated by the action of the driving force, and with this deceleration, the pulse When the interval exceeds a predetermined value and the inverted signal generation circuit inverts to the second state,
The first or second bistable circuit is reversed to the second state, and the supply of the electromagnetic brake drive signal to the reel motor drive circuit is stopped, and the actuation means is operated. A braking device for a tape recorder that operates the mechanical brake mechanism described above.