JPH06342544A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide the magnetic recording and reproducing device capable of imparting proper tension to a magnetic tape to cope with its stiffness even when it is different. CONSTITUTION:The magnetic recording and reproducing device is provided with a supply side reel motor part 7 for controlling the rotation of a supply reel 5 wound with the magnetic tape 4, a take-up side reel motor part 8, a rotary drum part 3 mounted with a magnetic head 2 and a tension detecting and setting part 10 for detecting tension of the magnetic tape and setting tension. Now, in order to obtain the optimum tension, the device is provided with a control part 16 for inputting an inlet neighboring output VIN and an outlet neighboring output VOUT of the rotary drum part, changing tension to be imparted to the tape within a prescribed range and deciding tension at the time when the sum of these two outputs becomes max. as the optimum tension of the magnetic tape. Then, at the time of normal recording and reproducing, the control is performed to impart the optimum tension to the tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing device such as a video device.

[0002]

2. Description of the Related Art In recent years, in magnetic tapes such as video tapes, the thickness of the magnetic tape has tended to be thin in order to prolong the recording / reproducing time when it is incorporated in a cassette. Further, in order to improve the recording / reproducing characteristics of the magnetic tape, the recording layer of the tape tends to be thin. Among the magnetic tapes, the coating type tape has a magnetic layer thickness of 0.1 to
The thickness becomes 0.4 μm, and a metal thin film tape (vapor deposition tape) having a thickness of 0.1 to 0.2 μm appears, and the thickness of the magnetic layer is about 1/10 of that of the conventional coating type tape. In general,
Since the stiffness (rigidity) of the magnetic tape is proportional to E · δ ³ (E: tape Young's modulus, δ: tape thickness),
The stiffness tends to decrease sharply as the tape thickness decreases.

[0003]

By the way, in a VTR, recording is performed obliquely on a magnetic tape half-wound, for example, by rotating a rotary drum carrying a magnetic head at a predetermined number of rotations. At this time, however, an air flow generated by the rotation of the drum flows between the drum and the tape, and a gap (spacing) of about several hundred Å is generated between the tip of the magnetic head and the tape. This spacing increases as the tape stiffness decreases, and with a low stiffness tape, the spacing loss increases and the output decreases. In addition, a tape having a low stiffness is susceptible to a difference in tape tension or air pressure between fields, and an FM output waveform abnormality (modulation) in one field occurs. That is, when the stiffness of the tape decreases, the contact state between the magnetic tape and the magnetic head, that is, the head contact, changes significantly as described above. Therefore, it is difficult to consistently obtain high recording / reproducing characteristics for magnetic tapes having different stiffnesses, and it is difficult to maintain tape compatibility.

Further, the sliding surface of the magnetic head has a curvature in the tape running direction and the head thickness direction in order to improve the contact with the tape. The radius of curvature does not change much in the tape running direction, but the head radius direction causes a different hit depending on the stiffness of the tape. Therefore, the radius of curvature changes greatly due to head friction, and the spacing differs for each tape with different stiffness. However, there is a problem that the compatibility of the tape is further deteriorated. In order to solve the above problems, attempts have been made to increase the Young's modulus of the tape as a measure to increase the stiffness of the thin magnetic tape, but as described above, the stiffness is proportional to the cube of the thickness of the tape. Due to changes, there is a limit to how thin it can be, and it has not been fully resolved. The present invention has been made in view of the above problems and was devised in order to effectively solve them, and its purpose is to provide appropriate tension corresponding to different stiffness of a magnetic tape. It is to provide a magnetic recording / reproducing apparatus capable of performing the above.

[0005]

According to the present invention, the spacing between the magnetic head and the magnetic tape strongly depends on the stiffness of the tape and the tension of the tape when the tape is running, and the spacing due to the decrease in the stiffness of the tape. The problem was solved by finding a point that can be improved by controlling the tension of the tape.

That is, in order to solve the above problems, the present invention rotates the supply reel motor unit for controlling the rotation of the supply reel on which the magnetic tape is wound, and the rotation of the take-up reel for winding the magnetic tape. A reel motor unit for controlling the winding, a rotary drum unit equipped with a magnetic head for recording / reproducing in contact with the magnetic tape, and a tension detection for detecting the tension of the running magnetic tape and setting the tension. In a magnetic recording / reproducing apparatus having a setting unit, the tension applied to the magnetic tape is changed within a predetermined range while inputting the output near the entrance and the output near the exit of the rotary drum unit, and the output near the input and the vicinity of the exit The controller is provided with a controller that applies a tension when the sum of the output and the output becomes maximum to the magnetic tape during normal running.

[0007]

Since the present invention is constructed as described above, the control section runs the magnetic tape on a trial basis when a new magnetic tape is mounted, and inputs the output near the inlet and the output near the outlet of the rotary drum. At the same time, the reel motor unit and the tension detection setting unit are operated to change the tension applied to the magnetic tape within a predetermined range. Then, the control unit controls the reel motor unit so as to apply the tension when the sum of the input near output and the output near output becomes maximum within this change range during normal running of the magnetic tape, that is, during recording and reproduction. And control the movable guide actuator section.
This makes it possible to perform recording / reproduction with stable characteristics even on magnetic tapes having different stiffnesses.

[0008]

An embodiment of a magnetic recording / reproducing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a main part of a magnetic recording / reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing a movable guide actuator section used in the apparatus shown in FIG. 1, and FIG. 3 is a 1-field FM of recorded information on a magnetic tape. It is a figure which shows an example of an output waveform.

As shown in the drawing, a magnetic recording / reproducing apparatus 1 such as a video tape recorder has a rotating drum portion 3 in which a magnetic head 2 for recording / reproducing is arranged in the peripheral portion and which is rotatable. For example, the half-wound magnetic tape 4 contacts the rotating drum 3 and runs. The magnetic tape 4 is wound around a supply reel 5 and a take-up reel 6, and the reels 5 and 6 are rotated by a supply-side reel motor unit 7 and a take-up reel motor unit 8, respectively. Is fitted into. Also, the magnetic tape 4 is
A plurality of guide pins 9 provided on the way of the traveling road
Also, the vehicle travels while being guided by the movable pin 11 of the movable guide actuator section 10 as the tension detection setting section.

The movable guide actuator section 10 is
It constitutes a part of a mechanism for applying a constant tension to the magnetic tape 4 while detecting the tension of the traveling magnetic tape 4. That is, as the actuator section 10, a known voice coil type movable actuator equipped with a position detection mechanism for the movable pin 11 is used, and the tension arm 1 has a base end portion swingably supported by a shaft 12.
3, the movable pin 11 is rotatably provided at the tip end thereof, and the magnetic tape 4 is hooked on the movable pin 11 so as to have a V shape. Further, the moving coil 1 is attached to the swinging tension arm 13.
4 is attached integrally, and a magnet 15 is fixedly provided on the base side so as to face the unit. And
The tension arm 13 is always biased in the A direction in FIG. 1, and the moving coil 14 and the magnet 15 are arranged so that the force for directing the movable pin 11 in the A direction becomes constant regardless of the rotational position of the tension arm 13. It is configured.
Further, the tension arm 13 is moved to the movable pin 11 by appropriately changing the current flowing to the moving coil 14.
It is possible to change the force that directs the direction A. Moreover, the rotation angle of the arm is always detected, and the control unit 1 including, for example, a microcomputer is used.
6 and a desired current from the control unit 16 via the coil driving unit 17 is input to the moving coil 14
It is designed to run to.

The rotation torque of the supply reel motor unit 7 is controlled by the drive current from the tension servo circuit 18, and the reel motor unit 8 of the take-up reel is also used.
The rotation is controlled by the drive current from the winding drive circuit 19. Then, the tension servo circuit 18
The take-up drive circuit 19 operates according to a command from the control unit 16.

Here, the tension applied to the running magnetic tape 4 is set by the current passed through the moving coil 14 which works in conjunction with the tension arm 13. That is, a change in tension is detected by the position detector of the tension arm 13, and the control unit 16 controls the supply reel motor unit 7 based on the detected output. A control is performed so as to apply a braking force to the magnetic tape 4 that is generated by generating a rotational torque that rotates in the winding direction that is the opposite direction to
Moreover, at this time, the rotational torque is controlled so that the tension arm 13 maintains a predetermined reference position (angle). As a result, the specified tension value set by the controller 16 can be applied to the magnetic tape 4.

In the present embodiment, an optimum tension determining operation is performed prior to a normal recording / reproducing operation by a command from the control section 16, the content of which is indicated by a point P1 on the rotary drum 3. Near the entrance, ie drum 3
Output at the point where contact between the magnetic tape 4 and the magnetic tape 4 starts (output near the inlet) V _IN and output near the outlet indicated by the point P2, that is, output at the point where contact between the drum 3 and the magnetic tape 4 ends (output near the outlet) V Paying attention to the sum of _OUT (V _IN + V _OUT ), the tension having the maximum value is set as the optimum tension for the magnetic tape 4. Then, during normal recording and reproduction, the movable guide actuator section 10 and the supply-side reel motor section 7 are controlled so as to always maintain the tension regulation value as the optimum tension.

Here, the reason why attention is paid to the sum of the input neighborhood output and the output neighborhood output of the rotary drum 3 will be described. FIG. 1 is a diagram showing an example of an FM output waveform of one field of a magnetic tape. The vicinity P1 of the inlet is a range having a certain width from the output start point, and the vicinity P2 of the output is also the output end point. Is a range in which a certain amount of width is provided to the front side, and in the present embodiment, the output is detected at a position distant from the output start point or the output end point by about 1/240 seconds, for example.

Then, the output V _IN near the entrance, the output V _OUT near the exit (normalized output), and their sum of various magnetic tapes having different stiffnesses as shown in Table 1 were measured while gradually changing the tension. However, the results shown in FIGS. 4 to 6 were obtained. Here, the stiffness is measured by using a loop stiffener tester manufactured by Toyo Seiki Co., Ltd., and a tape having a length of 100 mm is formed into a circular loop shape, and is expressed by a force for displacing the crushing distance to 20 mm. The vertical axes of FIGS. 4 to 6 represent the standardized output standardized by dividing the output by the maximum output of each tape, and the standardized output and the tendency of the output match. here,
VHS (trademark) type VTR is used to change the tape tension during running of 1/2 inch magnetic tape to 4 MHz.
The sine waveform of was recorded and reproduced, and the 1-field FM output waveform was examined.

[0016]

[Table 1]

The magnetic tape is a metal thin film tape, the magnetic tape is a coating tape having a thick tape thickness, the magnetic tape is a coating tape having a thicker tape thickness, and the stiffness gradually increases in that order. Figure 4
Is the standardized output of the magnetic tape when the tension is changed, Fig. 5 is the standardized output of the magnetic tape when the tension is changed, and Fig. 6 is the standardized output of the magnetic tape when the tension is changed. Are shown respectively. Here, each tension value represents the tape tension of the portion guided by the movable pin 11. In addition, FIG. 7 shows the tension dependence of the output fluctuation in one field of each magnetic tape (modulation: represented by the ratio (%) of the minimum output to the maximum output, and the larger the ratio, the smaller the output fluctuation). Indicates.

As is apparent from the figure, at the tension where the value of (V _IN + V _OUT ) is maximum, the modulation defined as described above becomes large, the output fluctuation becomes small, and the output value becomes large. Turns out. Therefore, the modulation can be monitored by the value of (V _IN + V _OUT ) without observing the envelope of the FM output waveform over one field. For example, for the magnetic tape, the optimum tension is about 6 g from FIGS. 4 and 7, about 9 g is the optimum tension for the magnetic tape from FIGS. 5 and 7, and about 6 g for the magnetic tape. About 1 from 7
It turns out that a tension of 0 g is the optimum tension.

In the present embodiment, the control unit 16 is programmed so that such an optimum tension determining operation is performed when a new magnetic tape is set, but it may be performed if necessary. Alternatively, the optimum tension determined once may be recorded on the magnetic tape, and then the optimum tension may be set at the time of recording / reproduction by reading the optimum tension.

Next, the operation of this embodiment configured as described above will be described. First, when a new magnetic tape 4 is set in the magnetic recording / reproducing apparatus 1, an optimum tension determining operation is performed automatically or manually according to a command from the control unit 16. That is, the tension servo circuit 18
The tension applied to the tape while controlling the rotation of the reel motor 7 on the supply side via a predetermined range, for example, 3 to 1
Recording / reproduction of a sinusoidal waveform of, for example, 4 MHz is performed by changing 1 g in a range of 2 g. At this time, the tension is set by setting a current flowing through the moving coil 14 through the coil driving unit 17 to a specific value, and the tension arm 13 maintains a preset rotation angle according to this value. The rotation torque of the supply-side reel motor unit 7 in the winding direction is controlled to apply the set tension to the magnetic tape. Here, the inlet vicinity output V _IN and the outlet vicinity output V _OUT at each tension value are stored in the control unit 16 and at the same time, the sum (V _IN + V _OUT ) of these outputs.
Is also sought and stored at the same time.

When the output detection in the tension range of 3 to 12 g is completed, the sum of the above outputs (V _IN +
The value of the tension when V _OUT ) becomes maximum is determined, this is determined as the optimum tension for the magnetic tape, and this value is stored. This completes the optimum tension determination operation. After that, during normal traveling for recording / reproducing the magnetic tape, the movable guide actuator unit 10 and the supply-side reel motor unit 7 are controlled so as to maintain the determined optimum tension. As a result, the spacing between the magnetic head 2 and the magnetic tape 4 becomes an appropriate value, and stable recording / reproduction can be performed without a decrease in output or an abnormal output waveform.

Since the above-described optimum tension determining operation is performed, for example, every time a new magnetic tape is set, stable recording / reproducing can be performed on magnetic tapes having different stiffnesses, and the compatibility of the tapes is high. It is possible to maintain. Actually, when each magnetic tape shown in the above Table 1 was subjected to the optimum tension determining operation, the optimum tensions of 6 g, 9 g and 10 g were respectively determined. When recording and reproducing a 4 MHz sinusoidal signal while applying each of these tensions to the corresponding magnetic tape, the output fluctuation of the 1-field FM output waveform was small, and the standardized output had the same value as in FIGS. 4 to 6. Was given. Also, after the magnetic tapes were run for 2 hours with the above tensions, the change in the radius of curvature of the head sliding surface in the thickness direction of the head was measured. The difference was small, and the compatibility of the tapes was sufficiently maintained. I was able to.

As described above, even if the stiffness is different due to the different magnetic tapes being set, the tension is changed correspondingly to always provide the optimum tension, so that the recording / reproducing can be performed with stable characteristics. It is possible to improve the tape compatibility. still,
In the above embodiment, the tension variable range is 3 to 1
Although it is set to 2 g, the amount of change is not limited to this, and the amount of change within this range is set to be 1 g at a time, but the amount of change is not limited to this, and may be changed more finely or by large values. Good. The movable guide actuator section 10 constitutes one example of a mechanism for applying a constant tension to the magnetic tape 4 while detecting the tension of the magnetic tape 4, and is not limited to the structure of the embodiment shown in FIG. , Any other configuration may be used.

[0024]

As described above, according to the magnetic recording / reproducing apparatus of the present invention, the following excellent operational effects can be exhibited. Since the optimum tension can be given to the magnetic tapes having different stiffness, it is possible to obtain the output without the output drop and the output waveform abnormality, and to always maintain the good recording / reproducing characteristics. The compatibility can be improved. Also, by applying an appropriate tension to the magnetic tape,
It is possible to reduce the difference in the change of the radius of curvature in the head thickness direction due to the sliding of the magnetic head due to the difference in the stiffness of the magnetic tape.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a movable guide actuator unit used in the device shown in FIG.

FIG. 3 is a diagram showing an example of a 1-field FM output waveform of recorded information on a magnetic tape.

FIG. 4 is a graph showing a standardized output of the magnetic tape when the tension is changed.

FIG. 5 is a graph showing the standardized output of the magnetic tape when the tension is changed.

FIG. 6 is a graph showing the standardized output of the magnetic tape when the tension is changed.

FIG. 7 is a graph showing the relationship between modulation and tension of each magnetic tape.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording / reproducing apparatus, 2 ... Magnetic head, 3 ... Rotating drum part, 4 ... Magnetic tape, 5 ... Supply reel, 6 ... Winding reel, 7 ... Supply side reel motor part, 8 ... Winding side reel motor part 10 ... Movable actuator part (tension detection setting part), 11 ... Movable pin, 13 ... Tension arm, 14 ... Moving coil, 16 ... Control part, 18 ... Tension servo circuit.

Claims (1)

[Claims] 1. A supply-side reel motor unit for controlling rotation of a supply reel on which a magnetic tape is wound, a winding-side reel motor unit for controlling rotation of a take-up reel for winding the magnetic tape, and the magnetic unit. In the magnetic recording / reproducing apparatus, a rotating drum unit is provided, which has a magnetic head mounted thereon for recording / reproducing in contact with the tape, and a tension detecting / setting unit for detecting tension of the traveling magnetic tape and setting the tension. The tension applied to the magnetic tape is changed within a predetermined range while inputting the output near the inlet and the output near the outlet, and the tension when the sum of the output near the output and the output near the output is maximum is set. A magnetic recording / reproducing apparatus comprising a control unit that applies the magnetic tape to the magnetic tape during normal traveling.