JPH0210498B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention operates by applying a brake to the reel stand while moving the magnetic head support stand of a magnetic recording/playback machine using a cassette to each mode (playback, cue, fast forward, etc.). The present invention relates to a movement control device for a magnetic head support stand that does not cause slack in the tape during stop and mode change.

In patent application No. 55-112751 filed by the same applicant, one motor for head shift is used exclusively for playback, cue (including recording), review, fast forward, rewind, and stop by rotating the motor forward, reverse, and stopping. He was practicing the mode. In playback, cue, and review modes, the head support is 4.5~
It moves about 6mm and the head support does not move when in fast forward, rewind, or stop mode, so the brake does not work when switching from fast forward or rewind mode to stop mode, and another means such as a plunger must be added. It was not possible to remove the slack in the tape. In consideration of this point, the present invention moves the head support for a short predetermined time when switching from fast forward or rewind mode to stop mode, and operates a control member in conjunction with the movement of this support to reel. After the stand has completely stopped, it is switched to stop mode.

Next, the present invention will be explained in detail using the drawings. In FIG. 1, the support base 2 is supported by the arrow B by the guide pins 2a, 2b, 2c set on the deck 1 made of a mild steel plate fixed to the main body, and the guide holes 3a, 3b, 3c into which these are inserted. Alternatively, it is supported so that it can move in the opposite direction. The spring 2d elastically repels the support base 2 in the direction of arrow B.

The magnetic head 4 and the erasing head 5 are fixed on a support base 2, and a support shaft 8a mounted on the support base 2 has a
A lever 8 is supported and resiliently repelled in the direction of arrow A by a spring (not shown). The lever 8 is provided with a pinch roller 7, which grips a magnetic tape (not shown) on the capstan 6 and moves it to the left. The symbol 6a is the bearing installed on the deck 1, and the symbol 6b is the capstan 6.
The flywheel 6b is fixed to the lower end of the flywheel 6b and is driven counterclockwise by conventional means.

The reel 1 is attached to the spindles 9 and 9a installed in the main body.
0, 10a and reel stands 11, 11a are rotatably supported. Further, flat ratchet teeth 12, 12a are provided on the outer periphery of the reel stands 11, 11a. The means for driving the reels 10, 10a may be any known means, such as an electric motor 13.
is fixed to the main body, and by forward rotation of its output shaft, the reel 10 is rotated, and by reverse rotation, the reel 10a
Rotate counterclockwise and clockwise, respectively,
This can be done by winding up a magnetic tape.

The cassette is mounted from above, and its hubs (not shown) are fitted onto the reels 10, 10a, respectively. In the state shown in FIG. 1, the magnetic tape is fed to the left by the pinch roller 7 and the capstan 6, and is wound around the hub via the reel 10, so it is in the playback mode (or recording mode).

The lever 15 is mounted on the shaft bearings 17a, 1 provided on the deck 1.
It is supported by a rotating shaft 16 supported by 7b, and can be rotated up and down. Braking parts 15a and 15b are provided at both ends of the side rod of the lever 15, and when they descend, they come into contact with the ratchet teeth and the reels 10 and 10a are rapidly braked. For this purpose, it is sufficient to float the end portion 15c of the lever 15 upward, and the effect is that this force can be minimized. This floating means will be described later. Also dotted line D
At the part indicated by , the lever 15 and the side rod part (braking part 15
By separating the parts (a and 15b) and connecting them with springs so that only the side rods can move left and right, the shock during braking can be absorbed. What is indicated by the symbol 35 is a recess provided in the deck 1, which is indicated by the same symbol as in FIG. 4a. The recess 35 has a cylindrical shape, and at the bottom thereof,
An annular magnet 36 is fixed. In order to ensure that the fixing position is accurately at a predetermined position, the bent portion 35a is
is provided. A flat disk-shaped armature is accommodated in the recess 35, and the deck 1 constitutes a yoke of a field magnet 36.

In FIG. 4b, field magnet 36 is shown. It is an annular ferrite magnet with alternating N and S poles with an opening angle of 90 degrees. The notch 36a is for positioning the magnetic pole of the field magnet 36 in a predetermined position with respect to the brushes 39, 40 shown in Figure C, and is provided on the surface where the field magnet 36 contacts the recess 35 in Figure A. It is. A protrusion (not shown) of the recess 35 can enter the notch 36a to fix the field magnet 36 in a predetermined position.

The part indicated by the symbol 38 in Fig. a is a plastic molding, which is fitted into the hole in the center of the recess 35 and fixed. Supports for brushes 39 and 40 and rotating shaft 1
It constitutes a bearing for rotatably supporting 6a. A view from above of the molded article 38 (hereinafter referred to as a bearing) is shown in Figure c. That is, the base 39
brushes 39, 4 with b and 40b fixed to the bearing 38;
A metal sliding contact is fixed to the free end of 0, and the contacts 39a and 40a are provided 90 degrees apart, and a
It is in sliding contact with the commutator 37a in the figure. This brush 3
9 and 40 from the power source, the armature 37
is rotated. The armature 37 is a disc-shaped armature, in which armature coils with an opening angle of 90 degrees are placed side by side, and the entire armature is made of plastic. Also, during molding, the small gear 16b in figure a
are made in one piece at the same time.

Details of the above-mentioned electric motor are disclosed in Japanese Patent Laid-Open No. 51-36507.

The item indicated by the symbol 34 in Fig. 1 is indicated by the same symbol in Fig. 4a, and is made of mild steel plate, so
It constitutes the magnetic path of the field magnet 36, and at the same time,
It also serves as a substrate on which a support shaft 17b for supporting gears 17, 17a is erected. The gears 17, 17a are made into one piece, and the gear 17 meshes with the gear 16b. The gear 16b is provided to protrude outward from the central hole of the mild steel plate 34. Mild steel plate 34
is fixed to deck 1 with screws. The gear 18 in FIG. 1 is supported by a support shaft 18a (installed on the deck 1) and meshes with the gear 17a.
Therefore, when the electric motor shown in FIG. 4 rotates, the gear 18
is rotated at reduced speed. Abutment pins 20, 21 are implanted in the gear 18, and the abutment pins 20, 21
protrudes upward through the hole 19 of the support base 2.

Next, referring to FIGS. 3a and 3b, the energization control means of the above-mentioned electric motor (denoted by symbol M) will be explained.

In FIG. 3b, terminals 29a and 29b are positive and negative input terminals. Transistors 30 and 31 are inverting circuits, and transistors 32 and 33 are flip-flop circuits. When the terminal 30a is at a low level, the transistors 30 and 33 are conductive, and the motor M is energized to the right and rotates in the normal direction.
Furthermore, when the terminal 30a becomes high level, the transistors 31 and 32 become conductive, and the motor M is configured to conduct current to the left and reverse rotation.

The terminals 29a and 29b are indicated by the same symbol in figure a. In figure a, symbols 24a, 24b
are the positive and negative poles of the power supply. Also, the electrical circuit in diagram b is a
It is shown as symbol 29 in the figure.

Terminal 30a in figure b is set to low level and terminal 26c
When is temporarily set to a high level, the motor M enters the normal rotation state as described above, and at this time, the charging current of the capacitor 26a causes the transistor 2 to
Since a base current of 5 is obtained and conducts, the resistance 2
Via 7a, the electric motor M is energized and started.
When a predetermined rotational speed is reached, the armature current decreases and the voltage at point E becomes higher than the voltage at point F, so that transistor 26 becomes conductive. Therefore, even after charging of the capacitor 26a is completed, the transistors 25 and 26 remain conductive and rotate normally.

When the load on electric motor M increases and the rotational speed decreases, the back electromotive force decreases, so the voltage at point E becomes F.
Since the voltage at the point becomes lower than the voltage at the point and the transistor 26 is turned non-conducting, the transistor 2
5 also becomes non-conductive, and energization of the electric motor M is stopped.

As understood from the above operation, the resistor 27
a, electric motor M, and resistors 27b and 27c constitute a bridge circuit. Further, by changing the ratio of the values of the resistors 27b and 27c, the rotational speed at which the electric motor M should be de-energized can be freely changed.

In the above case, when the electric motor M rotates in the normal direction and is overloaded and the current supply is stopped, if the terminal 30a is set to a high level and the input to the terminal 26c is temporarily set to a high level, the electric motor M rotates in the reverse direction. Since the capacitor 26a is temporarily discharged through the conduction of the transistor 26b, the transistors 25 and 26 become conductive and the motor M starts to rotate in reverse. However, when an overload occurs, the power is automatically cut off, as in the case of normal rotation.

The energization of the electric motor 13, the amplifying circuit of the magnetic head 4, and the capstan motor are controlled by well-known means. A well-known method is adopted in which rotating the electric motor 13 in the forward direction causes playback or fast-forwarding, and rotating the motor 13 in the reverse direction causes rewinding.

Next, the driving of the head support stand 2 will be explained in conjunction with the mechanism shown in FIG. When in the stop mode, when the terminal 30a in FIG. 3 is set to a low level and the terminal 26c is temporarily set to a high level, the electric motor M rotates in the normal direction, so the gear 18 is driven counterclockwise, and the contact pin 20 comes into contact with the notch 19b. The support stand 2 is moved in the direction opposite to the arrow B, and when the abutment pin 20 abuts the notch recess 19c to the position shown, rotation of the gear 18 and the electric motor M is inhibited. Therefore, the energization of the electric motor M is automatically stopped.

At this time, the electric motor 13 is controlled to rotate in the normal direction and wind the magnetic tape with a small torque, and enters the reproduction mode. Note that since the abutment pin 20 is at the dead center position, the return force by the spring 2d is completely blocked. If necessary, the resistor 28 shown in FIG. 3a can be added to supply a small amount of current to the motor M to make it more stable.

Next, terminal 30a is set to high level, and at the same time terminal 2
When 6c is temporarily set to a high level, the electric motor M is reversed as described above. The gear 18 rotates clockwise and the support base 2 retreats. When the abutting pin 21 abuts the notch 19d and moves the support base 2 forward, the abutting pin 21 abuts the notch protrusion 19e.
As the load increases, the electric motor M is de-energized and stopped. Since the distance between the abutment pin 21 and the support shaft 18a is set to be about 2 mm smaller than the distance between the abutment pin 20 and the support shaft 18a, the support stand 2 is at the dead center position of the gear 18 and is not in the regeneration mode. The cue is moved back about 2 millimeters and is oriented in the review mode position. At this time, if the electric motor 13 is rotated forward at high speed, it will be in the queue mode, and if it is rotated in the reverse direction, it will be in the review mode.

Next, when the terminal 30a is set to a low level and the terminal 26c is temporarily set to a high level at the same time, the transistor 26 becomes conductive and the capacitor 26a is discharged, so that the motor M rotates normally and returns to the regeneration mode.

FIG. 3c shows a circuit for converting to stop mode. When the stop command pushbutton switch is pressed, the electrical signal is input from the terminal 42 and is sent to the monostable circuit 4.
A high level signal that lasts for a predetermined time is obtained from the output terminal 43a through the output terminal 43a. The output of terminal 43a is input to terminal 26c in FIG. 3a. symbol 4
5 is an exclusive OR circuit, and symbol 46 is R
-S flip-flop, and part of the output of monostable circuit 43 and the output of R-S flip-flop 46 are input to an exclusive-OR circuit. R-S
A signal is input to the set terminal S and reset terminal R of the flip-flop at the time of mode switching. That is, in the playback, fast forward, or rewind mode, a high level signal is input from a control circuit (not shown) to the set terminal S (a low level signal is input to the reset terminal R), and in the cue or review mode, a high level signal is input to the set terminal S. A signal is input to the reset terminal R, and a low level signal is input to the set terminal S. ) The terminal 45a is as shown in Fig. 3b.
The signal is input to the terminal 30a of the terminal 30a.

During playback mode, the stop command pulse signal is sent to terminal 4.
2, the output terminal 43a temporarily becomes high level. At this time, the output of the R-S flip-flop 46 is at a low level, so the terminal 45a
transforms to a high level. Therefore, the electric motor M is temporarily reversed. However, soon terminals 43a and 45a
changes to low level, so transistor 3
0,33 conducts and an excessive armature current flows, a
The voltage at point E in the diagram drops and the transistor 26
becomes non-conductive, the transistor 25 also becomes non-conductive, and energization of the motor M is stopped. But the first
Since the illustrated abutment pin 20 has already escaped from the dead center position, the support base 2 is moved back by the elastic force of the spring 2d to reach the stop mode position. In this operation, the electric motor M is driven and rotated by the spring 2d and plays the role of a mechanical governor, so that the mode can be changed without generating any impact noise.

When a stop command pulse signal is input to terminal 42 in queue or review mode, terminal 43
a temporarily becomes high level, terminal 45a temporarily becomes low level, and after a certain period of time, monostable circuit 43
The output of the terminal 45a becomes a low level, and the output of the terminal 45a changes to a high level. Therefore, the electric motor M temporarily rotates in the forward direction and immediately tries to reverse the rotation, and the transistor 3
1 and 32 become conductive, an excessive current flows, and the voltage at point E in Figure a drops, transistors 26 and 25 become non-conductive, and the energization of the motor M is stopped. The support base 2 springs back to the stop mode position.

When the stop command push button switch is pressed, the mode changes to the stop mode as described above. Also, if you press the fast forward (or rewind) command button at this time,
Converts to fast forward (or rewind) mode. That is, the electric motor 13 rotates at high speed in forward or reverse rotation to wind up the tape at high speed.

When a stop command pulse signal is input to the terminal 42 in the fast forward or rewind mode, the terminal 43a
is temporarily at a high level, the terminal 45a is also temporarily at a high level, and the electric motor M is temporarily reversed.
At this time, a brake is applied to the reel stands 11 and 11a via a gear 18 and a cam portion 22a, which will be described later, to stop the rotation of the reel stands. However, the terminals 43a and 45a immediately change to low level, so the transistors 30 and 33 become conductive, and an excessive armature current flows, causing the voltage at point E in Figure a to drop, causing the transistor 26 to become non-conducting, causing the motor M to will be stopped. The amount of movement of the support base 2 is spring-backed.

By providing protruding cam portions 22b and 22a on the upper side of the gear 18 shown in the first figure, it is possible to apply a brake to the reel stand during mode switching as described next.

When the mode is changed from the queue or fast forward mode to the playback mode, when the magnetic tape is restrained by the capstan and the pinch roller, a large tension is applied and damages the magnetic tape. Further, on the reel 10a side, the magnetic tape may become slack, which may cause an accident. When switching from the rewind or review mode to the playback mode, the magnetic tape often loosens due to the inertia of the take-up reel 10, causing an accident. On the reel 10 side, the magnetic tape becomes slack, which may cause an accident. In order to eliminate this drawback, it is necessary to brake both reels at the time of the above-mentioned changeover. For this purpose, an electromagnetic plunger is commonly used, but the device of the present invention has the feature that this can be eliminated.

FIG. 2 is an explanatory diagram of the positions of the gear 18, cam portions 22a, 22b, and pins 20, 21 in each mode. a is in playback mode (or recording mode), b
is stop mode (or fast forward or rewind mode),
c indicates the queue (or review mode) state. The cam portions 22a and 22b provided so that the abutment pin 21 abuts the protrusion 19d (as shown in the first figure) and rotates synchronously with the gear 18 are in the position shown in FIG. 2c. When switching to playback mode, gear 1
Since the lever 8 rotates counterclockwise, the cam portion 22a comes into sliding contact with the end portion 15c of the lever 15. Cam part 22
The starting and ending parts of a are sloped, and the middle part is flat. As the gear 18 rotates, the end 15
c rises initially, continues to rise, then falls and escapes from the cam portion 22a. The gear 18 continues to rotate further, and the end 15c of the lever 15 comes into sliding contact with the cam part 22b and similarly moves up and down.

Therefore, when the lever 15 rotates up and down and the mode is changed from the queue mode to the playback mode, the braking portion 15b comes into contact with the ratchet teeth 12a, thereby inhibiting and braking the rotation of the reel 10a. Braking part 15b
When the reel comes into contact with the ratchet tooth 12a, the rising portion of the ratchet tooth 12a and the right side of the brake portion 15b come into contact, and the counterclockwise rotation of the reel stand 11a is inhibited and stopped. At this time, the braking part 15a also comes into sliding contact with the ratchet teeth 12.
There is no braking effect as it comes into sliding contact with the slope.

Furthermore, when changing from the review mode to the playback mode, both the ratchet teeth 12 and 12a are rotating clockwise, so the left side of the control section 15a comes into contact with the rising portion of the ratchet tooth 12 and brakes the reel stand 11. , the braking portion 15b slides on the sloped surface of the ratchet teeth 12a and has no braking effect. After this, the support base 2 is placed in the reproduction mode position, and the capstan 6, together with the pinch roller 7, pinches and restrains the magnetic tape. Therefore, it is possible to eliminate tangles due to damage and loosening of the magnetic tape.

In addition, when selecting a song, it is necessary to detect a no-signal zone between songs in queue or review mode and quickly switch to playback mode. However, during this time, the braking parts 15a, 15b via the cam parts 22a, 22b
Since the reels 10, 10a are temporarily braked and stopped by the vertical movement of the magnetic tape, the disadvantage that the magnetic tape moves intrusively until the beginning of the next track, which makes song selection inaccurate, is eliminated. effective. Although the braking mechanism has been described using ratchet teeth, it goes without saying that braking can be achieved in the same manner using a commonly used block brake member. In this case, the reel stands 11 and 11a are braked at the same time. Furthermore, if the shape of the hole 19 eliminates the notch concave portion 19c and widens the width of the notch convex portion 19e, when the abutment pins 20 and 21 abut on both sides, they will move away from the dead center position. By decreasing the value of the resistor 28 shown in FIG. 3 and increasing the applied current, the support base 2 can be positioned in the playback, queue, and review mode positions. In this case, the support stand 2 can be moved back to the stop mode by simply cutting off the power supply to the electric motor M due to the elastic force of the spring 9.

As described in each of the embodiments above, according to the present invention, the object stated at the beginning is achieved and the effects are significant.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the mechanism of the device of the present invention, and FIG. 2 shows the gear 18, cam parts 22a, 22b, pin 20,
3 is a control circuit diagram of the electric motor, and FIG. 4 is an explanatory diagram of the configuration of the electric motor. 1...Deck, 2...Support stand, 4, 5...Magnetic head, erase head, 6, 6a...Capstan, 7...Pinch roller, 8, 19a, 19
b, 15...Lever, 6b...Flywheel,
9, 9a, 8a, 18a... Support shaft, 14a, 14
b... Guide pin, 34... Mild steel plate, 10, 10a
... Reel, 11, 11a ... Reel stand, 12,
12a... Ratchet teeth, 13, M... Electric motor,
16b, 17, 17a, 18...gear, 20, 2
1... Contact pin, 15a, 15b... Control member,
25, 26, 26b, 30, 31, 32, 33...
...transistor, 37...armature, 38...shaft bearing, 39,40...brush.

Claims (1)

[Claims] 1. Through a gear driven at a reduced speed by an electric motor and the rotation of the gear in the forward direction, the support base supporting the magnetic head is moved in a direction close to the cassette to which it is attached, against the elastic force of the spring. At the very least, the above-mentioned support stand is oriented to the cue or review position against the elastic force of the spring through the device that orients the support stand to the playback position and the reverse rotation of the electric motor and gears mentioned above. In response to the stop command electric signal, the above-mentioned support base is moved away from the loaded cassette by the elastic force of the above-mentioned spring, and the de-energized electric motor is rotated as a mechanical governor to enter the stop mode. In a magnetic recording and reproducing machine using a cassette having a mode switching device consisting of a position localizing device and a mode switching device, rotating cam portions 22a and 22b are fixed to the side surface of the gear 18 and rotate synchronously.
Then, the reel stand 1 is moved by the braking parts 15a and 15b of the lever mechanism that are in sliding contact with the cam parts 22a and 22b.
By the rotation of the gear 18 and the braking device that brakes the outer periphery of the magnetic heads 1 and 11a, the support base of the magnetic head switches between the play mode position, the cue or review mode position, and the stop, fast forward, and rewind modes. The rotating cam portion 2
2a, 22b and a lever mechanism in sliding contact to brake and stop the reel stands 11, 11a, and a mode change command electric signal for normal rotation of the electric motor,
1. A movement control device for a magnetic head support stand, comprising an electric circuit for performing necessary rotation control such as reversing and stopping.