JPS5817984B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device that stabilizes tape running.

During constant speed running and fast forwarding during recording and playback of a magnetic recording and reproducing apparatus using a cassette, back tension is applied to the tape by applying a constant frictional force to the reel shaft.

As a result, the tape tension changes as the reel diameter changes, resulting in poor contact between the tape and the head.

In particular, the so-called 3-head type, in which the head is provided in the area where there is no bat, has a significant level fluctuation.

Furthermore, uneven friction between the reel shaft itself or the tape and the cassette half often causes wow, which is a drawback in recording and playback.

Furthermore, because there is little back tension during fast forwarding and rewinding, so-called irregular winding, in which the tape is wound in a disordered manner, has occurred.

The present invention has been made to eliminate these drawbacks, and aims to provide good tape running characteristics by applying a constant back tension to the tape using a mechanical tension servo system.

Particularly, in the case of a cassette tape recorder, it is difficult to perform tension servo on both reels due to restrictions on the opening of the cassette half.

Therefore, the present invention provides one tension arm to detect tape tension and control the braking force applied to both reels.

Furthermore, it is possible to mechanically perform tension servo in both rotational directions with one tension arm, and it is effective even in a narrow opening of a cassette or the like.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a magnetic recording/reproducing apparatus according to the present invention.

The cassette 1 is set at the position shown in the first figure, and the internal tape reel (not shown) is placed on the reel tables 2 and 30.
The rotating shafts 4 and 5 are fitted into each other, and the reel is rotated by the rotation of the rotating shafts.

The tape 6 inside the cassette is sandwiched between a capstan 7 and a pinch roller 8 and driven at a constant speed.

Further, as shown in a vertical cross-sectional view in FIG. 5, brake bands 9 and 10 are tied around the outer periphery of the reel table in a range of, for example, 1800 mm, so that a braking force can be applied to the reel.

One end of the brake band has movable levers 11 and 12.
Tension springs 13 and 14 apply tension to the brake band on the lever attached to the lever.

On the other hand, to drive both reels, an idler holding plate 18 is rotatably attached to a pulley 16 attached to the shaft of a reel motor 15, and a shaft 19 is mounted on the idler holding plate, as shown in the cross section of FIG. , an idler 12 is rotatably attached to the shaft, and a circumference of the idler is in contact with a pulley 16.

The shaft 19 is pivoted at the idler holding part with a pin 20 so as to be bent parallel to the pulley, and a spring 21 holds the shaft toward the idler, so that the idler 17
is pressed against the pulley 16.

on the front of the cassette. As shown in Figure 1, there is a playback head 22 in the center, and a recording head 23 in the small guide hole on the left.
is inserted, and the erase head 2 is inserted into the hole for the pinch roller on the left edge.
4 and a tension arm 25 are inserted, and abut on the tape with a guide pin 26.

Also for the left capstan. Guide shaft 27 in the hole
As shown in FIG. 1, the tape tension of the tape 6 is detected by a guide pin 26, and the tape 6 flows through a guide shaft 27 to each head.

The tension arm 25 is movable around a fulcrum 28, and either directly contacts the lever of the brake band 9 at the rear 29, or exerts movement on the operating lever 31 from the collar 12 via the auxiliary lever 30. It comes into contact with this lever 31.

The other end of each brake band is stopped by a back spring 34 or 35 via a holding lever 32 or 33.

This spring has a larger spring constant than the tension springs 13 and 14.

The head group and the pinch roller are mounted on a slide plate 37 and can be moved by a plunger solenoid 36 via a transmission lever 38 .

The transmission lever 38 rotates about a shaft 39, and acts on the brake lever 12 at the other end, so that when the solenoid is activated, the brake band is loosened as shown in the figure, and the brake action is released.

The operation will be explained below. During playback or recording, the plunger solenoid 36 operates as shown in Figure 1, the head group and the pinch roller move forward, and the pinch roller and capstan move the tape at a constant speed toward the take-up reel. Driven.

At the same time, the brake band 10 is removed, and the reel motor 15 is given counterclockwise rotational torque, which causes the idler holding plate 18 to move toward the take-up reel. Torque is applied to rotate the tape counterclockwise as shown by the arrow, and the tape is wound through the rotating shaft 5.

On the other hand, the tape tension is detected by the guide pin 26.

Back tension is applied to the shaft 4 by a brake band 9.

Here, the reel table 2 is rotated counterclockwise as shown by the arrow (because it is rotating counterclockwise, force is applied to the back spring 34 through the frictional force of the brake band, causing it to stretch a little, so the band moves counterclockwise as shown). The lever 11 is moving as shown by the solid line.

Further, at the lower end of the lever 11, another lever is arranged as shown in dotted lines as shown in FIG.

Therefore, in the above configuration, changes in the tension of the tape in contact with the guide pin 26 are applied to the lever 11 via the tension arm 25, whose rear part 29 comes into contact with the lever 11.

Therefore, when the back tension is strong, the tape tension increases and the force applied to the guide pin 26 increases, acting to tighten the brake band.

If the tape tension is weak on the pen pal, the force on the brake band will be reduced, which will increase the braking force and increase the tape tension.

In this way, the tape tension on the head surface is always kept constant.

Next, in the case of rewinding, the plunger solenoid 36 is turned off as shown in FIG. 3, and both brake bands are activated.

By turning the reel motor 15 clockwise as shown by the arrow in FIG. 3, the idler 17 is brought into pressure contact with the reel table 2, and the force from the motor pulley 16 is transmitted.

If a load is applied to the reel, the pressure on the idler 17 will increase further.

It has a so-called ``Kuikomi'' front-hand side. This causes the reels to rotate clockwise.

As for the brake, the tension springs 13 and 14 are softer than the pack springs 1 rings 34 and 35, so when the reel table 2 is rotated clockwise, the brake 1 can easily escape, but when it is rotated counterclockwise, it becomes stronger.

Conversely, when the reel table 3 is rotated in a clockwise direction, it is strong (when it is rotated in a counterclockwise direction, it is weak) - Kika.

Because of this, the reel 2 rotates clockwise, but at this time, a clockwise force is also applied to the brake band 9 due to friction, causing the back spring 34 to move in the direction of shrinking.

On the other hand, the reel table 3 is rotated clockwise by the tape, and a brake tension is applied to the tape by the brake band 10.

At this time, the brake band 10 is also rotated clockwise □
Due to the applied force, the back spring 35 expands.

Due to the difference in force on the springs 34 and 35, the lever 3
4, the tension arm 2 is over the lever 11.
A lever 31 is in contact with the rear part 29 of 5.

Here, if the tape tension is increased by applying tape tension to the guide pin 26 in the same way as when running at a constant speed, the arm 25 is pushed and the rear part 29 pushes the lever 31, and as a result, a force is applied to the brake band 10 via the lever 31. , the brake force is weakened, and as a result, the tape tension is reduced.

vice versa. If the tape tension is weak, the □ force applied to the lever 34 will be small, and the braking force will be strong.

Therefore, the tape tension during rewinding approaches a constant value.

Next. For fast forwarding, the solenoid 36 is similarly released and turns the reel motor 15 to the left as shown in FIG.

As a result, the operation is completely opposite to that of rewinding, and as a result, as shown in FIG. 1, the lever 11 moves to a position beyond the lever 31, making it possible to keep the back tension constant.

Here, since the guide shaft 27 is inserted into the position corresponding to the capstan hole of the tape cassette, the winding angle of the tape around the guide pin at the tip of the tension arm 26 increases, so the force on the tension arm increases. The accuracy and sensitivity of tape tension detection increases.

Furthermore, even if the erasing head is inserted as shown in FIG. 1, the winding angle of the tape around the guide pin 26 does not change and is stable.

Alternatively, the rotation detector can be rotated by the belt 40 from the reel table 3 on the winding side to servo the winding tension.

An example of a rotation detector is shown in Fig. 4, where a belt 40 and a pulley 4
1 and rotates the slit disk 42, which has slits on its circumference.

A lamp 43 and a light receiving element 44 such as a CDS are provided opposite this slit.

The output of this light-receiving element 44 is changed into an AC output such as on/off in proportion to the number of rotations of the winding reel.

The rotation speed can be detected by FM demodulating this AC output.

When running at a constant speed as shown in FIG. 1, this rotation detector can control the current flowing through the entire winding motor to keep the winding tension constant.

That is, when the rotation speed is fast, the motor current is decreased, and when the rotation speed is slow, it is increased.

This can be easily done by inverting the output of the rotation detector and applying it to the motor drive amplifier.

By doing this, when the amount of tape on the reel shaft is small,
That is, at the beginning of winding, the tape tension increases, but since the rotational speed is high, the current to the motor is reduced and the shift torque is reduced.

At the end of winding the tape, the winding diameter usually increases and the tape tension decreases, but the number of revolutions decreases and the motor torque increases to keep the tape tension constant.

In this embodiment, a case using a cassette has been described, but a reel-to-reel type may also be used.

As explained above, according to the present invention, even if there is an element that makes the tape tension unstable in the reel, guide, etc., the tape tension can always be kept constant by the servo, so wow, flutter, level fluctuation, etc. can be reduced. This can greatly contribute to improving sound quality.

In addition, since the difference in tape tension between the supply side and the take-up side is small, the pressing force of the pinch roller is small, and the solenoid is small, which improves operability even when manually operated with a small force.

Furthermore, it is possible to maintain a constant tape tension during fast forwarding, etc., resulting in uneven winding and no damage to the tape.

Also, by applying tension servo to both reels with one tension arm, the above-mentioned effects can be achieved and can greatly contribute to improved performance.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention. FIG. 2 is a sectional view of the reel and drive motor section. FIG. 3 is a plan view showing the main parts of one embodiment for explaining the operation. FIG. 4 is a sectional view of the rotation detection section. FIG. 5 is a sectional view of the reel table section. FIG. 6 is a sectional view of a portion of the servo lever. 1 is a cassette, 6 is a tape, 8 is a pinch roller, 15 is a reel morph, 17 is an idler, 22 is a playback head, 2
3 is a recording head, 24 is an erasing head, and 25 is a tension arm.

Claims (1)

[Claims] 1. A tape tension detecting means, two brake means for applying a load to a supply reel and a take-up reel, and an engaging means such as a movable lever fixed to one end of the brake means, Alternatively, the regeneration is performed by applying a displacement from the tape tension detection means to one of the brake means of the supply or take-up reel located upstream with respect to the running direction of the tape through the engagement means during fast forwarding or rewinding. A magnetic recording and reproducing device characterized in that the tension of the tape is kept constant. 2. A tape tension detection means, two brake means for applying a load to a supply reel and a take-up reel, and a stopper at one end of the brake means. When recording or reproducing fast forwarding or rewinding, the tape tension is applied to one of the brake means of the supply or take-up reel on the upstream side with respect to the tape running direction. The displacement from the detection means is applied via the engagement means, and the rotational speed of one of the supply or take-up reels to which no displacement is applied from the tape tension detection means is detected, and the displacement is determined by the detected force. 1. A magnetic recording and reproducing apparatus characterized in that the tape tension is kept constant by controlling one of the drive motors of the supply or take-up reel, which is not provided with a tape tension.