JPS585468B2 - jacket jacket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used in a magnetic sheet type recording/reproducing device that records and reproduces signals by bringing a magnetic head into contact with the magnetic layer surface of a flexible magnetic sheet, which is a rotating recording medium. This invention relates to a jacket type magnetic recording medium.

FIG. 1 shows an example of a conventional magnetic sheet type recording/reproducing device and a jacket type magnetic recording medium used in the device.

To explain this, the jacket type magnetic recording medium includes a flexible magnetic sheet removably attached to a hub 200 installed on the shaft 58 of a motor 56 attached to a substrate 34, and one side of the magnetic sheet 12. A plate 16 made of a hard material is installed facing the magnetic sheet 12.

The plate 14 is disposed on the opposite side of the plate 16 across the magnetic sheet 12 and has an opening 26 for ejecting the head. The attached head chip 84 passes through the ejection opening 26 and contacts the magnetic sheet 12.

Furthermore, openings 30 and 24 are provided in the center of the plate 16 and the center of the plate 14, so that as the magnetic sheet 12 rotates, the magnetic sheet 12 and the plate 14
When the air present between the plates 14 and 14 is discharged to the outside by centrifugal force based on its viscosity, an amount of air equal to the amount discharged can flow in.

Furthermore, the plates 16 and 14 are coupled via a spacer 18.

The lower surface of the plate 14 is connected to a pin 42 provided on the substrate 34.
is supported.

There are two ways of thinking about holding the magnetic sheet 12 that rotates once in this conventional device.

One is by setting the magnetic sheet 12 exactly in the center of the plates 16 and 14 and making the distribution state of the air flows 260 and 280 flowing on both sides of the magnetic sheet 12 symmetrical with respect to the magnetic sheet 12. The idea is to offset the Bernoulli force acting on the magnetic sheet 12 and hold the magnetic sheet 12 straight, but in reality it is difficult to set the magnetic sheet 12 at the center of the plates 16 and 14. And furthermore.

Such an equilibrium state can be achieved by the magnetic sheet 12.
This is limited to the case where is a perfectly straight plane.

In reality, it is difficult to implement and is not used much.

Another method is to use one plate, for example plate 1.
The magnetic sheet 12 is set so that the distance between the plate 14 and the magnetic sheet 12 is sufficiently larger than the distance between the plate 16 and the magnetic sheet 12. The hydrodynamic Bernoulli force caused by the airflow 280 generated between the plate 16 can be ignored, and it can be considered that the magnetic sheet 12 receives only the hydrodynamic Bernoulli force caused by the airflow 260 generated between the plate 16.

At this time, the equilibrium state of the forces acting on the magnetic sheet 12 is as follows.

In other words, the centrifugal force generated as the magnetic sheet 12 rotates acts as tension.

The Bernoulli force caused by the air flow 260 acts to deform the magnetic sheet 12, and when the deformation stress caused by the deformation of the magnetic sheet 12 becomes equal to the Bernoulli force caused by the air flow 260, the magnetic sheet 1 rotates once in balance.
The shape of 2 is determined.

As shown in FIG. 2, the shape of the magnetic sheet 12 at this time is such that the distance from the plate 16 becomes smaller toward the periphery, and the part of the magnetic sheet 12 that rotates stably It is known that the distance between the magnetic sheet 12 and the plate 16 is about 0.2 mm.

Therefore, when attaching the magnetic sheet 12 to the holding member 60, if the distance between the position and the plate 16 is large, the magnetic sheet 12
but.

Attachment to the central holding member 80, which has strict constraints, requires large deformation in the vicinity of the holding member 80.

On the other hand, in the magnetic sheet 12 that rotates with the central portion fixed, the centrifugal force is maximum at the central fixed portion.

The resistance force against deformation of the magnetic sheet 12 is maximum near the fixed portion, and the magnetic sheet 12 is less likely to be deformed due to the hydrodynamic Bernoulli force near the portion where it is attached to the holding member 60.

Therefore. When attempting to stably rotate the magnetic sheet 12 along the plate 16, there is a problem in that very strict precision is required for positioning the magnetic sheet 12 to the holding member 60 relative to the plate 16.

The present invention aims to eliminate the drawbacks of the above-mentioned conventional examples. Regardless of the position of the magnetic sheet when the magnetic sheet is attached to the shaft when it is stationary, when the magnetic sheet is rotated, the magnetic sorting is fixed to the plate. The present invention provides a jacket type magnetic recording medium that can be rotated at intervals.

An embodiment of the present invention will be described in detail below.

First, FIG. 3 is a sectional front view showing the structure of a jacket type magnetic recording and reproducing apparatus, and the jacket type magnetic recording and reproducing apparatus is mainly composed of four parts.

That is, a jacket-type magnetic recording medium (hereinafter abbreviated as a recording medium) and a holding portion of the recording medium.

They are a rotational drive transmission system and an electromagnetic conversion system that is movable in the radial direction of the rotation center of the rotational drive system.

FIG. 4, FIG. 5, and FIG. 6 are front views and exploded views showing the structure of a recording medium in an embodiment of the present invention.

FIG. 7 is a front view showing a state in which the recording medium is attached to a jacket type magnetic recording/reproducing apparatus, in order to explain the holding portion of the recording medium.

8 to 17 are diagrams illustrating a recording/reproducing apparatus that can use this recording medium, and FIG. 8 is a front view showing an example of a holding member used in the rotational drive transmission system.

9 and 10 are a plan view and a front view showing other examples of the holding member.

Further, FIGS. 11, 12, 13, and 14 are a front view and a side view showing the configuration of the electromagnetic conversion system.

Hereinafter, the structure and function of each part will be explained in detail with reference to the drawings.

First, a recording medium in an embodiment of the present invention will be explained with reference to FIGS. 4.5.6.

This recording medium includes a circular flexible magnetic sheet (hereinafter simply referred to as "sheet") 12 having a magnetic layer on at least one side, whose central portion is fixed to a bubble 10, and a plate 14 placed opposite the sheet 12. and a plate 16 made of a hard material placed opposite to the plate 14 with the sheet 12 in between, and the plates 14 and 16 being spaced apart from each other by a constant distance.

It also includes a plurality of spacers 18 set so that the outer edges of both the plates are open.

Furthermore, the bubble 10 and the seat 12 have an opening 2 in the center.
0 and an opening 22 located near the outer edge of the opening 20, and the plate 14 has an opening 24 in the center and an opening 26 for allowing the electromagnetic conversion system to access the sheet 12. and a plurality of openings 28 used for holding recording media.

The plate 16 is provided with an opening 30 having a smaller diameter than the opening 24 of the plate 14 in the center thereof, and furthermore, the portion of the plate 14 facing the opening 26 for accessing the electromagnetic conversion system is made of an elastic hard body 32. .

Next, the configuration of the holding portion for holding the recording medium will be explained with reference to FIG.

The holding part is the substrate 34 of the jacket type magnetic recording/reproducing device.
A case 40 is rotatable about the shaft 38 through a bearing 36 and a shaft 38 provided in the case 40, and has an opening 39 for inserting the recording medium.
and a plurality of pins 42 fixed on the substrate 34 and provided in positions to fit into the plurality of openings 28 on the plate 14 of the recording medium, and further on the case 40.

Apertures 44, 46, 48 and 50 are provided in the portions opposite the apertures 24, 26, 28 and 30 provided on the plates 14 and 16 of the recording medium, respectively, and a spring 52 is provided in the portion opposite the aperture 48. is provided.

Furthermore, the substrate 34 is supported by feet 54.

Next, the configuration of a transmission system for rotationally driving this recording medium will be explained with reference to FIGS. 8, 9, and 10.

The rotational drive transmission system includes a shaft 58 that is rotationally driven by a motor 56 that is fixed to the substrate 34, and a holding member 60 that is fixed to the shaft 58.

In the device shown in FIG. 8, the holding member 60 has a tapered portion 62.

It has a parallel convex portion 64 and a flange 66, and further includes a flange 66.
is provided with an opening 68 at a radial position from the center of rotation corresponding to the opening 22 provided in the bub 10 and the seat 12, and the pin 70 passes through the opening 68 into the member 72 fixed to the brim 66. It is installed with a device that can freely protrude through a spring 74 whose one end is supported by the spring 74.

Moreover, in the apparatus shown in FIGS. 9 and 10, in addition to the above-mentioned components.

Further, an open lower portion 5 is provided through the tapered portion 62 and the parallel convex portion 64, and the holding member 6 is provided with the open lower portion 5.
0 is in a hollow state, and a plurality of springs 76 are fixed at one end to the hollow portion, and a plurality of protruding members 80 are fixed to the other end of the spring 76 and have a tapered portion 78 at the tip. ing.

In this case, the portion where the spring 76 is fixed to the holding member 60 is provided on the side whose rotational phase is more advanced than the portion where the protruding member 80 is fixed.

That is, in FIG. 9, the rotation direction of the holding member 60 is the direction indicated by the arrow 82, and the portion where the spring 76 is fixed to the holding member 60 is the protruding member 80. It is set so that the rotational phase is advanced from the fixed part.

Further, at least one of the plurality of springs 76 has a spring constant different from the other springs, or at least one of the plurality of protruding members 80 has a different mass than the other protruding members. There is.

Next, according to Figures 11.12 and 13.14.

The configuration of an electromagnetic conversion system for recording and reproducing information on this recording medium will be explained.

In FIG. 11.12, a head par 86 to which a head chip 84 is fixed is a bearing 86 provided on a substrate 34.
The shaft 90 is connected to the shaft 90 supported by the shaft 8 through a bearing 92.
It is fixed so that it can rotate freely around the center.

Further, a pin 94 is fixed to one end of the head par 86, and a spring 98 is stretched between the pin 94 and a pin 96 having a notch provided on the substrate 34.

A rotational torque is applied to the head par 86 in a direction in which the head chip 84 approaches the recording medium.

Further, an arm 102 is provided which is rotatable about a fulcrum 100 so as to be in contact with a part of the head par 86, and one end is rotatable about a plunger 104 provided on the base plate 34 via the fulcrum 106. It is fixed to.

The other end is fixed to the other end of a spring 108 whose one end is fixed to the base plate 34, and when the plunger 104 is not in operation, it cancels out the rotational torque applied to the head par 86 by the spring 98, and moves the head par 86 to the base plate. A pressing force is applied in the direction of 34.

Furthermore, one end of the pulley 1 is fixed to a pin 110 provided on another part of the head par 86, and is attached to a shaft 116 of a pulse motor 114 via a guide pulley 112.
A wire line 12 is provided which is connected to 18;
This makes it possible to move the head par 86 in the direction of the arrow 122 by operating the pulse motor 114.

The structure of each part of the jacket-type magnetic recording/reproducing apparatus has been described above, and now the operation and function of each part will be explained.

First, when a recording medium is inserted through the opening 39 of the case 40, the case 40 is lifted upward about the shaft 38 as a fulcrum as shown in FIG.

A pin 42 and a holding member 60 for holding a recording medium.

This is designed to prevent interference with the inserted recording medium.

After inserting the recording medium, the case 40 is rotated downward about the shaft 38 and the opening 20 in the center of the bubble 10 and the sheet 12 is opened.
is guided by the tapered portion 62 of the holding member 60, fits into the parallel convex portion 64, and is mounted on the flange 66.

The recording medium holding pin 42 is inserted into the openings 48 and 28 provided in the case 40 and the recording medium plate 14.
The spring 52 provided on the inner surface of the case 40 contacts the lower surface of the recording medium plate 16 to determine the setting position of the entire recording medium, and the spring 52 provided on the inner surface of the case 40 pushes the portion facing the pin 42 from the upper surface of the recording medium plate 16. Press.

The recording medium can be held in place by applying pressure to hold the recording medium.

At this time, since the pin 42 directly defines the set height on the lower surface of the plate 16, for example, the pin 42 is attached to the outer surface of the plate 14.
Compared to the case where the plates 16 are brought into contact with each other, there is an advantage that error factors in the set positioning of the plate 16, such as variations in the thickness of the plate 14, the presence of warpage or distortion, and variations in the thickness of the spacer 18, are eliminated.

Further, since the pressing force of the spring 52 acts only on the solid plate 16, the recording medium holding force that is considered when pressing the hollow body constituted by the plates 14 and 16 and the spacer 18 causes the plate of the recording medium to be 14 and plate 16 are deformed.

Further, since the spring 52 applies a pressing force to a portion facing the contact portion between the pin 42 and the plate 16, the plate 16
This has the advantage that no bending stress is applied to the plate 16, and therefore the plate 16 can be held without strain while maintaining its shape at the time of manufacture, and the recording medium can be positioned with high precision.

Further, for example, in the process of inserting a recording medium into the case 40, the bubble 10 and the sheet 12 built into the recording medium are displaced downward due to their own weight between the plates 14 and 16, and the opening 20 is opened at the tapered portion of the holding member 60. There is a risk that the plate may move out of the range guided by the plate 14 and the plate 16, but to solve this problem of positional deviation, as shown by the two-dot chain line in Fig. The plurality of spacers 18 that are held are guided by the bub 10 and the opening 20 of the sheet 12 by the tapered portion 62 of the holding member 60 due to the dimensional difference between the diameter of the virtual circle inscribed in the plurality of spacers 18 and the diameter of the circular sheet 12. This can be prevented by arranging the settings so that the variation in set position obtained is less than the allowable limit.

In this case, it is convenient for the spacer 18 to have an isotropic shape.

For example, if a circular spacer 18 is used, the circular spacer 18 is isotropic in shape with respect to the center position as long as the center position of the circular spacer 18 is determined.

Regardless of the direction in which the spacer 18 is set, the above-mentioned virtual inscribed circle is uniquely determined.

By arranging the spacer 18 as described above, the range in which the bubble 10 and the seat 12 can move between the plates 14 and 16 can be limited.

This allows the opening 20 of the sheet 12 to be positioned within a range that can be guided by the tapered portion 62 of the holding member 60.

Furthermore, at the time when the recording medium is installed in the case 40 as described above, the pins 70 provided on the holding member 60 and the openings 22 on the bubbles 10 and sheet 12 are generally in different phases, and therefore They do not fit into each other, and the protruding pin 70 is pushed downward by the weight of the bubble 10, the seat 12, etc., and is in a displaced state.

When the holding member 60 starts rotating and the pin 70 and the opening 22 are in phase, they fit together.

The rotational driving force of the holding member 60 is applied to the bub 10 by the pin 70.
and is transmitted to the sheet 12, where,
Since the pin 70 can freely protrude and is displaced downward by the weight of the seat 12, etc., the pin 70 can damage the bub 10 and the seat 12 even when the pin 70 is rotating without being fitted into the opening 22. The risk can be significantly reduced.

That is, by making the rotational driving force transmission pin 70 of the holding member 60 freely protrusive, it is possible to prevent damage to the bub 10 and the sheet 12 when a recording medium is attached and at the initial stage of rotation of the holding member.

Furthermore, if the pin 70 is fixed, the pin 70 will interfere with the sheet 12 or the plate 16 of the recording medium when it is attached to the case 40 of the recording medium volume holding part, and the recording medium itself will interfere with the case 40. Although there is a risk of interfering with the installation, 1
By using the extrudable pin 70 according to the present invention, such a risk can be eliminated.

Through the above process, the recording medium is loaded, and the rotational driving force of the motor 56 is transmitted to the sheet 12 by the pin 70 on the holding member 60, and the sheet 12 starts to rotate. It is known that a waving phenomenon occurs over the entire surface of the sheet 12 due to the flexibility of There is a risk that severe relative movement will occur between the sheet 12 and the head chip 84, causing significant damage to the sheet 12, and possibly even damaging the head chip 84.

Therefore, in this device, as shown in FIGS. 11 and 12, the plunger 104 is not operated until the seat 12 reaches a high-speed steady rotation state, and the arm 102 is pressed against the head par 86 by the attractive force of the spring 108. By keeping the head par 86 pressed downward and waiting, a mechanism is used to keep the head chip 84 and the seat out of contact, thereby reducing the risk of damage to the head chip 84 and the seat 12 as described above. It is being removed.

After the seat 12 reaches a required high-speed rotation state, the plunger 104 is energized, and the contact portion of the arm 102 with the head par 86 is lifted upward via the fulcrum 106 and the fulcrum 100, and the head par 86 is rotated by the force of the spring 98. The head chip 84 is rotated about the fulcrum 90 in a direction that lifts the head chip 84 upward.

The head chip 84 can now come into contact with the sheet 12 which is rotating at high speed.

Detection that the seat 12 has reached a steady state of rotation can be done, for example, by installing a magnet 12 in the rotational drive part as shown in FIG.
8 is attached, and the change in magnetic flux caused by the rotation of the magnet 128 is detected by the magnetic head 130, thereby generating a pulse signal once per rotation, and adjusting the frequency of the pulse signal to the steady rotation speed of the motor. This is done by comparing the frequencies with the corresponding frequencies, and when the two match, the plunger can be energized.

Furthermore, in this mechanism, even when the head chip 84 and the seat 12 are in contact with each other, it is the elastic force of the spring 98 that applies the mutual load between them, and therefore, as shown in FIG. 12, the notch of the pin 96 By providing a plurality of springs 98 and changing the amount of extension of the springs 98, it is not only possible to easily adjust the relative load, but also to adjust the spring constant of the springs 98 and the weight of the head par 86, head chip 84, etc. Since the head par 86 has a vibration system with a mode determined by
By controlling its own weight, it is also possible to provide the head par 86 with a vibration mode that is compatible with the rotation system of the seat 12.

Here, by using a device as described above.

However, the seat 12 and the head chip 84 can be protected during the transient state of the rotation end of the seat 12.

Further, when the plunger 104 is actuated and the head par 86 is rotated upward around the axis 90 by the spring 98, and the head chip 84 contacts the seat 12, the momentum of the head chip 84 and the head par 86, which move one rotation, is calculated between the head chip 84 and the seat. 12, a large force acts between the head chip 84 and the sheet 12, and there is a risk that the head chip 84 and the sheet 12 will be damaged.

In order to eliminate this risk, this device is provided with an arm 134 that is rotatable while receiving the oil damping effect with respect to a fulcrum 132 that has an oil damping effect, as shown in FIG.

To explain this, the arm 134 rotates about the fulcrum 132, and one end of the arm 134 is connected to the substrate 3.
4, and the other end of the arm 134 is connected to the fulcrum 10 by the spring 108 when the plunger 104 is not actuated.
The spring 108 is in a state in which it is in partial contact with the arm 102 which is receiving a downward pressing force around 0, so that the pressing force of the spring 108 is applied to the arm 134 via the arm 102, and this causes the spring 136 to act on the arm 134. The rotational torques are canceled and the arm 134 is about the fulcrum 132.

In FIG. 15, clockwise rotational torque is being applied.

Here, consider a case where the plunger 104 is energized after the seat 12 starts rotating and reaches a required number of rotations.

The arm 102 is moved by the spring 1 due to the attractive force of the plunger 104.
08, the arm 1 rotates upward around the fulcrum 100, the contact between the arm 102 and the arm 134 is broken, and the arm 1
34 receives a counterclockwise torque around the fulcrum 132 due to the elastic force of the spring 136.

At the same time, the plunger 104 also binds the head par 86.
Since it is released at the time when the spring 98 is activated, the rotational torque by the spring 98 also begins to act on the head par 86.

Therefore, the torque from the above-mentioned spring 98 and the torque from the spring 136 act on the fulcrum 132 .

The fulcrum '132 receives the above-mentioned two torques, but as mentioned above, since it fails to have an oil damper function, it generates a resistance force proportional to the rotational angular velocity of the arm 134, thereby keeping the rotational angular velocity of the arm 134 at a low speed. It is possible,
The head par 86 and the arm 134 remain integrated through their contact portion.

At low speed, it approaches the seat 12 which is rotating at high speed.

When the seat 12 and the head chip 84 come into gentle contact with each other due to the action of the oil damper, the rotational movement of the head par 86 stops, and the spring 98 causes the seat 12 and the head chip 84 to come into contact with each other.
However, since the torque from the spring 136 on the arm 134 is still acting,
The arm 134 continues to rotate further and is no longer in contact with the head par 86.

Therefore, when the head chip 84 is in contact with the seat 12, the head par 86 is in contact with the arm 102 and the arm 1.
34, and can simply maintain the vibration mode determined by the spring 98, head par 86, etc.

Conversely, when the power to the plunger 104 is cut off, the elastic force of the spring 108 causes the arm 102 to first cancel out the force of the spring 136 and move the arm 134 roughly to the spring 98.
A pressing force is applied in the direction of canceling the force and separating both the head pars 86 from the seat 12, allowing the seat 12 to return to its state before starting rotation.

By using such a mechanism, head par 8
This makes it possible to reduce the impact when the head chip 84 and the sheet 12 come into contact without changing the vibration mode that the head chip 84 originally has.

By employing the above-described mechanism, damage to the sheet 12 and the head chip 84 due to undulation of the sheet 12 that occurs when the sheet 12 starts to rotate, and damage to the sheet 12 when the head chip 84 contacts the sheet 12 can be avoided. And damage to the head chip 84 can be prevented even after the seat 12 reaches a steady state of rotation and the head chip 84 comes into contact with the seat 12.

There is also a risk that the seat 12 and head chip 84 may be damaged by external vibrations or sudden impacts.

For example, if we consider the case where an impact force is applied from the outside, the impact force has components over a wide range of frequencies, so it resonates with the vibration mode of the head par 86 mentioned above, causing the head par 86 to vibrate greatly. There is a danger that

When the head par 86 vibrates due to an external force, the head chip 84 attached to the head par 86 and in contact with the sheet 12 moves relative to the sheet 12, and at a certain moment presses the sheet 12. Collision with the lower surface of the plate 16 made of a hard material causes an impact force to act on the seat 12 and the head chip 84, and this impact force may locally damage the seat 12 or damage the head chip 84. There is a risk that chipping may occur.

One possible way to eliminate this risk is to apply an oil damper to the shaft 90, which is the fulcrum of the head par 86, but such a method would limit the vibration mode of the head par 86.

This is not appropriate because the vibration mode is changed from the vibration mode determined by the elastic modulus of the spring 98, the weight of the head par 86, etc. mentioned above.

Therefore, in this device, as shown in FIG. 5, the portion of the plate 16 made of a hard material that corresponds to the portion where the head chip 84 and the sheet 12 come into contact is made of an elastic soft body 32. A method is used in which the impact force acting from the vibrating head par 86 is relaxed and absorbed by the elastic body 32.

Specifically, an opening is provided in a portion of the plate 16 corresponding to the portion where the head chip 84 and the sheet 12 are in contact with each other, and the opening is filled with an elastic and soft adhesive such as silicone rubber. However, as a result, even if the jacket-type magnetic recording/reproducing device is subjected to an impact, the sheet 1
2 and the head chip 84 can be prevented from being damaged.

In a recording and reproducing apparatus that uses the flexible sheet 12 as a recording medium, a major condition for obtaining good recording and reproducing conditions is stability of rotation of the sheet 12 in a high speed rotation state.

In order to stabilize the rotating seat 12, it is said that it is necessary to provide a surface that serves as a rotation reference when the seat 12 rotates, but in this device, the method of setting the reference surface is Be considerate.

Description will be given based on a front view showing the configuration of the recording medium in FIG. 4 and FIG. 17.

In this device, the head chip 84 is in contact with the sheet 12 from the plate 14 side through an opening 26 provided in the plate 14.

Here, the plate 14 is used as a reference surface when the seat 12 is rotated.

However, in this device, the plate 16 located on the side opposite to the side where the head chip 84 contacts the sheet 12 is used as the rotation reference plane.

That is, we focused on the fact that one of the major factors that determines the rotation state of the seat 12 is the flow state of the viscous air flows 260 and 280 generated on the surface of the seat 12 rotating at high speed.

At least the airflow generated between the rotating seat 12 and the plate that regulates the rotation of the seat 12, that is, the reference surface, is controlled so that the airflow can easily maintain a steady laminar flow. In the path are a head chip 84 and a head par 86 that can act as a dam for the airflow. In addition, the structure is characterized in that there is no opening or the like that would cause a sudden change in the cross-sectional area of the flow path.

In other words, the opening 26 necessary for bringing the head chip 84 and its support system, which are essential for a magnetic recording/reproducing device, close to the rotating sheet 12, and the opening 28 necessary for supporting the recording medium, The plate 16 that serves as the reference surface and the sheet 12 are coated without any film on the plate 16 that serves as the reference surface.
This means that it is provided on the side of the plate 14, which is a non-reference surface provided on opposite sides of the plate.

Seat 1 that rotates 0 times by adopting the above configuration
2 and the contact portion of the head chip 84.

It is possible to eliminate local disturbance factors for the air flow in the part of the sheet 12 corresponding to the opening 26, which is generated at least between the rotating sheet 12 and the plate 16 serving as a reference surface for the sheet 12. As for the air flow 260, conditions can be established to easily maintain a laminar flow state, which has the effect of increasing stability during rotation of the sheet 12.

The above-mentioned method is a means for removing local disturbance factors for maintaining the stability of the rotating seat 12, but the bubble 10 and the seat 12 are also considered as factors related to the overall stability of the rotating seat 12. It is known that the initial setting distance from the surface, that is, the plate 16 in this embodiment, is important.

Generally speaking, it is said that about 0.2 mm is appropriate for the above-mentioned initial setting interval, but the setting tolerance is very narrow. There is also a problem in that a strict positioning accuracy is required between the holding member 60 on which the sheet 12 is mounted and the plate 16 which serves as a reference surface when the sheet 12 is rotated.

Therefore, in this device, the plates 14 and 16 of the recording medium are devised, and the holding member 6 shown in FIG.
0 and the above-mentioned drawbacks can be eliminated by paying attention to the fitting portion between the bubble 10 and the holding member 60.

That is, the diameter of the opening 30 provided at the center of the plate 16, which is the reference plane for the rotation of the seat 12, is made smaller than the diameter of the opening 24 at the center of the plate 14, which is the non-reference plane.
The amount of air flowing in from the opening 30 during rotation of the opening 24 is
The air pressure between the seat 12 and the plate 16 during one rotation is made smaller than the air pressure between the seat 12 and the plate 14 by making the amount of air flowing in from the bubble 10 and the plate 16 smaller than that between the seat 12 and the plate 14. When the opening 20 in the center of the sheet 12 is fitted into the parallel protrusion 64 of the holding member 60, the bubble 1 is fitted with a large dimensional difference.
A feature is that the sheet 12 to which 0 is fixed can be freely displaced in the axial direction of the holding member 60 regardless of whether it is at rest or during one rotation.

With this configuration, when the seat 12 is rotating at high speed, a force is applied to the seat 12 from the plate 14 side toward the plate 16, and furthermore, the seat 12 is simply held parallel to the holding member 60. Since the seat 12 is movable in the axial direction of the holding member 60 by simply fitting into the convex portion 64, the rotational position of the seat 12 changes due to the above-mentioned pressing force in a high speed rotation state, and the seat 12 moves near the lower surface of the plate 16. It will start rotating.

At this time, the distance between the plate 16 and the seat 12 rotating at high speed is determined by the flow rate of air flowing through the opening 30.

Therefore, the distance between the plate 16 and the sheet 12 can be directly controlled by the diameter of the opening 30.

In reality, if the diameter of the opening 30 is too small, the load resistance during rotation of the seat 12 will increase, and if the diameter is too large, the pressing force sufficient to change the rotational position of the seat 12 will not be generated. There is a usable range of 30 diameters.

In this embodiment, the diameter of the seat 12 is 175, and the number of revolutions per rotation is 360.
It has been experimentally confirmed that it is optimal for the diameter of the opening 30 to be in the range of about 6 mm to 10 mm for the diameter of the opening 24 of 60 mm at 0 rpm. Regardless of the initial setting distance between the seat 12 and the plate 16, the seat 12 floats on the flange 66 of the holding member by the mechanism described above as the seat 12 rotates, and the seat 12 maintains a small distance from the plate 16. Through this, stable rotation can be achieved.

Furthermore, when the bub 10 and the seat 12 are attached to the holding member 60 by simply fitting together as described above, the seat 12 is placed on the collar 66 of the holding member 60. It also has a degree of freedom in which it can move in the radial direction by a distance corresponding to the dimensional difference in the fit.

Here, assuming that the holding member 60 is driven by the motor 56 and starts rotating, the force acting on the holding member 60 and the seat 12 from the start of one rotation to the time of steady rotation.

Let's consider the movement of the seat 12.

For simplicity, let us assume that the driving torque of the holding member 60 is a constant value T.

However, ■ = Moment of inertia of the rotating part 0: Phase angle of the rotating part f1 f2: T and the angular acceleration and angular velocity of rotation are related by the following equation showing a functional form.

Until steady rotation is reached, the resistance due to the moment of inertia of the rotating body in the first term on the right side of equation (1) is the main load of the driving torque, and in steady rotation, the resistance due to the rotational angular velocity in the second term on the right side of equation (1) is the main load of driving torque. But.

In both cases the total load torque is equal to the drive torque.

The state at that time is schematically shown in FIG.

In FIG. 16, point O is the center of gravity of the sheet 12, and point P is the point of action that transmits the drive from the pin 70 to the opening 22.

The dot indicates the point of action of the combined torque of the total load, and the drive torque and load torque are both T and act in opposite directions.

In this state, finding the force acting on each point, 0P=l'1,
If 0L=12, the effect on point P becomes 1 point 0, that is, sheet 1
With respect to the point of application of the force F, that is, the point of contact with the opening 22 of the pin 70, a force will act on the center of gravity of the sheet 12 in the opposite direction to the direction of rotation of the sheet 12. As a result, the sheet 12 moves in a fixed direction determined by the direction of rotation of the sheet 12, and both of them are basted and continue to maintain a fixed positional relationship.

That is, no matter what positional relationship the seat 12 is mounted on the collar 66 of the holding member 60 when it is stationary, the rotational driving force transmission pin 7 is attached to the seat 12 when the holding member 60 starts rotating.
A force determined by the zero position and the load torque (immediate rotation torque) is applied, and the set position automatically changes to come into contact with the parallel protrusion 64 of the holding member 60 at a certain position of the opening 20.

From then on, the force will continue to be applied as described above. For example, when the seat 12 rotates clockwise,
The contact state is as shown in FIG. 17.

Here, variations in the one-rotation torque simply result in variations in the contact pressure between the seat 12 and the holding member 60, and do not affect the positional relationship of contact between the two.

As mentioned above, by using the holding member 60 shown in FIG.
Ease of setting positioning for 6.

This improves the reproducibility of the centering of the sheet 12, but depending on the conditions of use, it may be better to fix the sheet 12 to the collar 66 of the holding member 60 when the sheet 12 is rotating at high speed. Sometimes it's good.

In such a case, a holding device shown in FIGS. 9 and 10 provides a method for accurately fixing and centering the sheet 12.

The holding member 60 in this device has a pin 70 that transmits the rotational driving force of the holding member to the seat 12 from a collar 6 so that it can freely protrude.
6 is the same as that shown in FIG. It is characterized by the provision of a protruding member 80 having a tapered portion 78 at its tip.

When the holding member 60 starts rotating, a centrifugal force determined by the radius from the center of rotation of the holding member 60, the rotational angular velocity of the holding member 60, and the mass of the protruding member 80 acts on the protruding member 80, and the protruding member 80 is pushed outward, causing a displacement according to the elastic constant of the leaf spring 76.

Therefore, when the holding member 60 reaches a steady rotation speed, the hub 10 is fixed to the center of the seat 12 within a range where the protruding member 80 is displaced by the centrifugal force acting on the protruding member 80.
If installed, the protruding member 80 and the hub 10 will come into contact with each other, and the protruding member 80 will press the hub 10.

The pressing force on the hub 10 at this time is determined by the centrifugal force acting on the protruding member 80 and the amount of distortion of the leaf spring 76 in the state where the hub 10 and the protruding member are in contact with each other. It is given as the difference between the elastic force of

Therefore, when the shape and rotation speed of the holding member 60 are constant, the pressing force can be controlled by changing the mass of the protruding member 80 and/or the elastic constant of the leaf spring 76.

Here, if the elastic constants and masses of the plurality of leaf springs 76 and the protruding members 80 are all equal without variation, the resultant force of the plurality of pressing forces acting on the hub 10 from the plurality of protruding members 80 is zero. By doing so, the centering accuracy of the hub 10 and seat 12 can be ensured.

In reality, it is difficult to make the elastic constant of the leaf spring 76 and the mass of the protruding member 80 exactly the same, and if a plurality of holding devices are manufactured, there is a risk that their centering conditions will all be different. However, this problem can be solved by changing the elastic constant of at least one of the plurality of leaf springs 76 and/or at least one of the plurality of protruding members 80.
By changing the mass of the plurality of protruding members 80, the resultant force of the pressing force acting on the hub 10 may be made not to be zero, but always in a constant direction.

By doing this, the initial phase when the seat 12 is attached to the holding member 60 is the same as that between the pin 70 on the holding member and the hub 10.
and the opening 22 of the sheet 12, the sheet 12 is provided by the flange 66 of the holding member 60.
By receiving a pressing force in a certain direction from the protruding member 80 at a fixed phase position with respect to the holding member 60, centering is achieved with good reproducibility and compatibility between the plurality of holding members is ensured. It turns out.

Further, since a tapered portion 78 is provided at the tip of the protruding member 80, a component force is generated that acts on the hub 10 and the seat 12 in the direction of the collar 66 of the holding member 60 from the pressing force acting in a direction parallel to the seat 12. Therefore, during high-speed rotation, the sheet 12 remains pressed and fixed onto the collar 66 by the above component force.

In addition, the elastic constant of the leaf spring 76 and/or the mass of the protruding member 80 is described above as a method for making the resultant force of a plurality of pressing forces from the plurality of protruding members 80 to the bubble 10 have a non-zero value in a certain direction. Although a similar effect has been described above, a similar effect can also be obtained by changing the phase position of the plurality of protruding members 80 when attached to the holding member 60.

That is, when installing the three protruding members 80 as illustrated in FIG.
By setting the angle to 0 degrees, the resultant force of the pressing force from each protruding member 80 can also be set to a non-zero finite value.

Furthermore, in the holding device shown in FIG.
By providing the fixed portion of the holding member 60 at a rotational phase position advanced from the fixed portion of the protruding member 80, there is no risk that the leaf spring 76 will buckle due to the force acting on the protruding member 80. As a result, the risk of the leaf spring 76 breaking is eliminated, and the protruding member 80 is reliably displaced outward when the holding member 60 starts rotating, thereby creating a pressing force against the bub 10. It is something that

As detailed above, the jacket type magnetic recording medium of the present invention includes a flexible magnetic sheet that can be attached to and detached from a shaft that can freely rotate nine times;
a first plate made of a hard material held opposite the magnetic sheet and having an opening in the center; a second plate having
The diameter of the opening in the center of the first plate is smaller than the diameter of the opening in the center of the second plate. By creating a difference in the magnitude of the Bernoulli force caused by the generated air flow on the surface of the flexible magnetic sheet, a pressing force in a fixed direction is applied to the flexible magnetic sheet,
Thereby, the rotational position of the flexible magnetic sheet can be changed to the vicinity of the reference plate that regulates the rotation of the flexible magnetic sheet.

As a result, when a flexible magnetic sheet is used with its center fixed to a holding member, in conventional jacket-type magnetic recording media, it is difficult to connect the flexible magnetic sheet and the reference plate for stable recording and reproduction. Whereas the setting distance was 0.2 mm or less, the jacket type magnetic recording medium according to the present invention can now perform stable recording and reproduction up to a distance that is about three times the above setting, increasing the setting tolerance range. This has advantages such as large tolerances in assembly dimensions of the rotating system of flexible magnetic sheets, ease of manufacture, and cost reduction.

[Brief explanation of drawings]

FIG. 1 is a sectional front view showing the configuration of a conventional magnetic sheet type recording/reproducing device, FIG. 2 is a sectional front view showing the state of the rotating magnetic sheet in the above device, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a cross-sectional front view showing the structure of a jacket-type magnetic recording and reproducing apparatus using a jacket-type magnetic recording medium in FIG. FIG. 5 is an exploded perspective view showing the configuration of the jacket type magnetic recording medium, FIG. 6 is a plan view showing the jacket type magnetic recording medium with one plate removed, and FIG.
The figure is a front view showing the jacket-type magnetic recording medium attached to the jacket-type magnetic recording/reproducing device, and FIG. 8 is a front view showing the structure of the flexible sheet holding device used in the device of FIGS. 3 and 7. FIG. 9 is a plan view showing the configuration of the flexible sheet holding device, and FIG. 10 is a front view of the same device. Fig. 11 is a front view showing the configuration of the holding mechanism of the electromagnetic transducer used in the devices shown in Figs. 3 and 7, Fig. 12 is a side view of the device shown in Fig. 11, and Fig. 13 is a Front view showing the configuration of the feeding mechanism of the electromagnetic transducer used in the device, No. 14
The figure is a side view of the device. FIG. 15 is a front view showing a buffer mechanism for vertical movement of the electromagnetic transducer used in the devices shown in FIGS. 3 and 7. FIG. FIG. 16 is a schematic diagram showing the state of the force acting on the flexible sheet during one rotation, and FIG. 17 is a front view showing the positional relationship of the flexible sheet with respect to the holding member during five rotations. 60... Holding member, 56... Motor, 58... Shaft, 12
...magnetic sheet, 16...plate. 26...opening, 14...plate, 30...opening. 24...Opening, 18...Spacer, 260...Air flow,
280... Air flow, 10... Bubble, 20... Opening, 22
...Aperture, 28...Aperture.

Claims (1)

[Scope of Claims] 1. A flexible magnetic sheet that can be attached to and detached from a rotatable shaft; a first plate made of a hard material held opposite to the magnetic sheet and having an opening in the center; a second plate installed opposite to the first plate and having an opening in the center so as to sandwich the magnetic sort;
By setting and holding the outer circumferences of the first and second plates in an open state, when the magnetic sheet is rotated, the first and second plates are arranged between the magnetic sort and the first plate and the second plate, respectively. A flow path for air flowing in from the opening in the center of the first plate is formed so that negative pressure is generated on both sides of the magnetic sheet by the two air flows, and the opening in the center of the first plate By making the diameter smaller than the diameter of the opening in the center of the second plate, a difference is created in the magnitude of the negative pressure generated by the two air flows, and the second plate is in contact with the magnetic sheet. The magnetic sheet is provided with an opening for insertion of a magnetic head that performs an electromagnetic transduction action, and the magnetic sheet has an engaging portion for positioning on the shaft and an engaging portion for inheriting the rotational driving force from the shaft. and has. A jacket type magnetic recording medium characterized in that the magnetic sort is configured to be able to be displaced in the axial direction of the shaft even when the magnetic sort is mounted and positioned on the shaft.