JPH02110852A - Magnetic disk driver - Google Patents

Abstract

PURPOSE:To improve the performance of information transmission and reception between a disk and a magnetic head by bending a flexible disk backward in a pressing direction by a collet and supporting a jacket from the side of a chassis. CONSTITUTION:A collar part 35a of a collet 35 and a support face 12a of a hub support 12 are shaped to bend a flexible disk 52 backward toward a chassis 1 through the mutual cooperation. Moreover, the jacket support face is projected from the chassis buttom face and the height of the jacket support face lowers by at least the thickness of a jacket 53 than the signal transmitting/receiving face of the 1st magnetic head. The jacket is supported by the jacket support face arranged on the chassis by bending the disk toward the chassis and the relation of position with a magnetic head is given accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic disk drives, and more particularly to improvements in those using flexible magnetic disks.

[Prior Art] A device for chucking a flexible magnetic disk in a magnetic disk drive device consists of a hub attached to a drive shaft and a collet fitted into the hub, as exemplified in Japanese Utility Model Publication No. 58-13509. The disk is pressed and gripped by the hub and collet from both sides, and the collet slightly presses the central circular opening of the magnetic disk while fitting into the cylindrical inner surface of the hub so that the magnetic disk is accurately centered. It is configured to expand.

[Problems to be Solved by the Invention] In conventional devices, the diameter of the receiving surface of the hub holder is larger than the diameter of the collet pressing part, so when the collet is pressed by the outer leg pressing mechanism, the collet is inserted into the center hole of the flexible disk. Since the center hole is pushed apart by the wedge member, the center hole receives force from the collet in the direction of increasing its diameter.

However, although the flexible disk is flexible in the thickness direction, it is not flexible in the plane direction.

Therefore, when the collet receives a force in the plane direction that pushes it outward from the inside of the center hole, the donut-shaped flexible disk warps upward in an umbrella shape because it does not have enough rigidity in the thickness direction to maintain its flatness against the external force. It ends up. Furthermore, numerous small wrinkles are generated from the center hole that contacts the collet toward the center of the flexible disk, which deteriorates the flatness of the flexible disk, making it impossible to obtain good contact with the magnetic head.

In order to solve the above problem, as disclosed in Japanese Patent Application Laid-open No. 61-160875, the upwardly curved flexible disk is pushed down with a bat, and the small wrinkles that come together due to the pushing force are blocked as if by a breakwater. As shown, the current was rectified just before reaching the magnetic head. These matters will be explained below using figures. A conventional chucking configuration is shown in FIG. The diameter of the collar portion 35a of the collet 35 is smaller than the diameter of the receiving surface 12Aa of the conventional hub receiver 12A.

In such a combination, when the periphery of the center hole 52a is strongly pressed and clamped by the collar portion 35a, the flexible disk 52 is easily deformed.

However, the receiving surface 12 of the flat part with a large area is located below.
Because of Aa, it is only allowed to warp upward. It is like an open umbrella turned upside down and turned toward the sky. Furthermore, an eighth
Complex small j as shown in the figure! ! 54 occurs. Naturally, the number and size of the small wis 54 increases and becomes larger as the center hole 52a is pushed wider. FIG. 9 shows a combination of the above-mentioned warpage and fine wrinkles 54. Due to the warp angle θ shown in FIG. 9, in the conventional device, the first magnetic head 20
Since the 20A signal transfer surface and the flexible disk 52 are no longer located on the same surface, it was necessary to return the surface of the flexible disk 52 to the signal transfer surface 20a of the first magnetic head 20 using a special pressing mechanism from the upper plate 32 side. . Also,
The fine wrinkles 54 are rectified by pressing the jacket 53 with a pad made of maltblane or the like provided on the tip of the pressing mechanism or the back surface of the upper Fi 32. Normally, in such a conventional configuration, the wrinkles 54 are rectified by pressing the jacket 53 with a pad made of maltblane or the like provided on the tip of the pressing mechanism or the back surface of the upper Fi 32. A jacket holder was protruded from the chassis 1 at the position where the jacket 53 was bent to prevent it from warping more than necessary. However, this method is not only technically complex, it is not always easy to bring the contact characteristics with the magnetic head to an ideal state, and it is also quite difficult to maintain the characteristics stably. As a result, the performance of information exchange between the disk and the magnetic head may be affected.

In addition, in order to achieve these requirements, the structure becomes complicated and the number of parts increases, resulting in problems such as undesirable costs.

[Means for solving the problem] The solution to the above problem is to write to a magnetic disk,
It consists of a magnetic head device that performs reading, a drive motor that drives the magnetic disk, a hub holder rotated by the drive motor, and a collet that has a pressing mechanism.The inner peripheral portion of the flexible disk is exposed from the jacket when the collet presses against the hub holder. In a device comprising a catching device that presses and holds the magnetic head device and a chassis that supports the magnetic head device and the chucking device, when the flexible disk is chucked, the flexible disk is warped in the pressing direction of the collet and deformed into an umbrella shape. This is achieved by providing a means for bending the flexible disk in the direction of pressure by the collet and supporting the jacket from the chassis side.

[Function] According to the present invention, the flexible disk is forcibly bent back in the pressing direction by the collet, that is, toward the chassis, so that the flexible disk contacts and presses the inner surface of the jacket on the chassis side. At this time, since the jacket on the side that the flexible disk contacts is supported by the jacket receiving surface from the chassis side, a pressing force acts on the contact surface due to the above-mentioned warping of the flexible disk, and on the other hand, a reaction force due to this pressing force is applied to the above-mentioned side of the flexible disk. It acts on the abutting surface, thereby exerting a rectifying action on the flexible disk. In this case, the rectification is provided based on a structurally stable chassis, so it is extremely superior to the conventional case where it is provided by a pressing pad etc. through an elastic body. 6 In addition, the jacket is supported from the chassis side. This eliminates the need for a conventional rectifying mechanism using a pad or the like via a special elastic body, and the configuration of the magnetic disk drive device is simplified.

While the flexible disk is being chucked, the flexible disk that is warped in the direction of pressure by the collet comes into contact with the inner surface of the jacket received by the jacket receiving surface.
Due to this contact force, fine wrinkles on the flexible disk that occur during chucking are automatically and appropriately rectified. This improves the contact performance of the head with respect to the flexible disk.

When the magnetic disk is chucked by a chucking device consisting of a hub and a collet, the flexible disk tends to warp in the opposite direction with respect to the chassis. In order for the magnetic head to exchange information in such a state, the magnetic head must be moved in the direction of deformation of the flexible disk, or the warped flexible disk must be flattened by external force or partially brought into contact with the magnetic head. In the past, pressing down was carried out using a pushing down device using a pad or the like. Although the method of partially pushing down the flexible head considerably improves the contact between the magnetic head and the disk, it is still not sufficient, and it is quite difficult to properly adjust the arrangement and number of pads. Met. Since the arrangement of the pads is moderately restricted due to the configuration of the magnetic disk device, it is not always possible to realize an ideal arrangement.

Furthermore, such lifting devices complicate the overall structure of the device, which of course increases the cost of the device.

According to the present invention, by bending the disk toward the chassis, the jacket is supported by the jacket receiving surface disposed on the chassis, thereby making it possible to provide an accurate positional relationship with the magnetic head.

Further, the wave-like deformation that occurs in the flexible disk is rectified by the pressing force between the jacket receiver and the disk via the jacket. The rectifying effect of the jacket receiving surface in such a state is revolutionary compared to the conventional one using a pad or the like. The reason for this is that the jacket receiver maintains a sufficient area and an accurate and ideal positional relationship with respect to the information exchange section by the magnetic head of the disk.

The contact pressure between the head and the flexible disk changes depending on the relative positional relationship between the signal exchange surface of the head and the flexible disk. That is, the relative positional relationship between the two should basically be negative, but if the negative absolute value is large, the contact pressure will increase, and if it is small, the contact pressure will be small.

When a flexible disk is placed on the receiving surface of a hub from above and a collet descends from above to press and hold the flexible disk, conventionally the flexible disk is warped in the opposite direction to the pressing direction of the collet, that is, upward. Therefore, in order to maintain such a relationship, the information transfer position of the magnetic head had to be located at a high position relative to the receiving surface of the hub.

On the other hand, in the present invention, since the flexible disk is forcibly bent downward, the position of the flexible disk is always lower than the position of the hub receiving surface unless the jacket receiving surface is present. As long as the jacket receiving surface is higher than the position corresponding to the warped position of the flexible disk plus the thickness of the jacket, the position of the flexible disk is uniquely determined by the position of the jacket receiving surface. . That is, the position of the flexible disk is given by the position of the jacket receiving surface plus the thickness of the jacket.

In the present invention, the interrelationship between the position of the information exchange surface of the magnetic head, the position of the receiving surface of the hub which is the reference surface of the flexible disk, and the position of the jacket receiving surface on the chassis that regulates the position of the flexible disk is particularly important. . According to experiments conducted by the inventors, the effect of the present invention can be obtained even if the position of the surface of the magnetic head is set higher than the position of the receiving surface of the hub. It was best if the position was equal to or lower than the position of the hub receiving surface. FIG. 16 shows the results of measuring the waviness of the magnetic disk near the magnetic head and the output voltage while the magnetic disk was mounted on the magnetic disk drive and operated. The waviness was measured using a reflective optical gap sensor, and the output voltage was measured using a synchroscope as the reproduced output voltage of a signal previously recorded on a magnetic disk.

Figure A shows the results of a survey of waviness and output voltage when a magnetic disk is installed in a conventional magnetic disk drive, and Figure B shows a similar result when a magnetic disk is installed in a magnetic disk drive of the present invention. This shows the results of the survey. In both figures, the waviness Un of the magnetic disk drive of the present invention is approximately one-half of the waviness Uc of the conventional magnetic disk drive, which is an extremely small value. One of the evaluation methods for magnetic disk drives is the stability of the playback output voltage (
This is generally called modulation. ) There is a way to check. Modulation is generally expressed as a percentage by dividing the minimum output voltage by the maximum output voltage.

Modulation W b of conventional magnetic disk drive
Comparing W c / W ac with the modulation W b n /W a of the magnetic disk drive of the present invention, it can be seen that the modulation of the magnetic disk drive of the present invention is improved. Also, the reproduction output voltage value is higher in the magnetic disk drive of the present invention.

Yes, it has high performance.

[Example] A description will be given below based on the drawings. 1 is a chassis and includes the entire body. A drive motor 2 is attached to the bottom of the chassis 1 with screws. The drive motor 2 is the same as a general one, with a rotor 3, a torque magnet 4. Stator 5. Rotational force generating parts such as the excitation coil 6 and the control board 7, the rotor seat 8, and the rotor set screw 9. housing 10
, a ball bearing 11, a hub receiver 12, and other shaft systems. The housing 10 extends from a plurality of mounting protrusions and is attached to the bottom of the chassis 1 with drive motor mounting screws 13. Like the drive motor 2, the main board 14 is also attached to the bottom of the chassis 1 with main board mounting screws 15.

At the bottom of the chassis 1 on the opposite side of the main board 15, a guide shaft 16 is connected to a shaft holding plate 17 and a holding plate tightening screw 18.
It is installed by The guide shafts 16 are disposed on both sides of the carriage 19, and guide the carriage 19 so that it can move forward and backward only with respect to the center of the hub receiver 12. The carriage 19 has a first magnetic head 20 at its tip.
A head arm spring 22 integrally formed with a helad arm 21 is attached to the rear end of the head arm 21 with an arm set screw 24 via a metal fitting 23. head arm 2
2 has a second magnetic head 25 at its tip. Reference numeral 26 denotes a head pressing spring, which presses the first magnetic head 20 with appropriate pressure.
and a second magnetic head 25 are provided to sandwich and oppose the flexible disk. 27a and 27b have the first magnetic head 20 and the second magnetic head 25 fixed in the center with adhesive, respectively, and the edges are connected to the carriage 19 and the head arm 2.
A gimbal for the first magnetic head and a cymbal for the second magnetic head are adhesively fixed to the tip of the magnetic head.

The side of the carriage 19 is connected to a stepping motor 29 via a steel belt 28 with a belt tightening screw 30. The stepping motor 29 is fixed to the side wall of the chassis 1 with stepping motor mounting screws 31.

Reference numeral 32 denotes an upper plate made of thin plate steel or the like and fixed to the chassis 1 with screws, etc., and serves as a base member on which a flexible disk chucking mechanism and a loading/unloading mechanism for the second magnetic head 25, which will be described later, are mounted. . A leaf spring 33 is supported so as to rotate about a leaf spring shaft 34 provided on the side of the upper plate 32 as a fulcrum. The leaf spring 33 is bifurcated near the rotation fulcrum, one of which serves as a collet pushing spring 33a for pressing the collet 35 against the hub receiver 12 via various parts to be described later, and the other protrudes from the helad arm 22. The head loading arm 33b is assembled below the head loading projection 22a.

36 is a shaft, and a cam 36a is integrally formed at the tip thereof. Further, the shaft 36 is rotatably supported by a metal plate 37 in the middle thereof, and the metal plate 37 is fixed to the upper plate 32 by metal plate mounting screws 38.

39 is a return spring that urges the leaf spring 33 in a direction opposite to the upper plate 32. The collet extractor 40 has a collet shaft 41 planted,
One end is attached to the attachment boss 42 by a collet plate attachment screw 43. The lower end of the attachment boss 42 is fixed to the upper plate 32.

The tip of the collet pushing spring 33a is bifurcated, and the small diameter portion 44a of the sleeve 44 is held between the two forks. The top of the sleeve 44 is a large diameter section 44b, and a small diameter section 44b.
Below a is a shoulder portion 44c. Below the shoulder portion 44c is a ball bearing mounting portion 44d that is fixed to the inner diameter of the ball bearing 45, and further below is a C-ring groove 44e for mounting the C-ring 46.

The ball bearing 45 is inserted and fixed to the lower surface of the shoulder portion 44C. A pusher ring 47 is inserted into the outer ring of the ball bearing 45. 48 is a collet push spring;
One end comes into contact with the pressure ring 47 and the other end comes into contact with the collet 35.

After inserting the collet 35 into the sleeve 44, the waves are stopped by C.
The ring 46 is landed in the C-ring groove 44e.

The collet pushing spring 48 is sized relative to the pusher ring and the collet 35 so as to have an appropriate stretching force between the pusher ring and the collet 35.

The leaf spring 33 pushed up by the return spring 39 is held with the tip of the collet pushing spring 33a abutting against the lower surface of the collet plate 40.

A front panel 49 is attached to the front side of the chassis 1. A knob 50 passes through the front panel 49 and is inserted and fixed onto the protruding shirts 1 to 36. The front panel 49 is provided with an opening 49a in which the magnetic disk 51 is inserted.

The magnetic disk 51 (FIG. 15) consists of a flexible disk 52 which is a signal recording medium and a jacket 53 to protect it. A center hole 52a for chucking is provided at the center of the flexible disk 52.

A collet escape hole 53a and a head window 53b, which are larger than the center hole 52a, are also provided at the center of the jacket 53. The jacket 53 also has a folded part 53.
c is a provision.

The components of the magnetic disk drive device described above are the same as those of conventional magnetic disk drive devices, and the operation is also the same. In other words, the magnetic disk 51 is
．． When the lever return spring 33a is pushed down by the cam 36a shown in FIG. 4, when the knob 5o is rotated 90 degrees clockwise in FIG.
When the shoulder part 44C of 4 is pushed down, the ball bearing 45,
The pusher ring 47, collet pushing spring 48, and collet 35 descend together. When the collet 35 descends by a certain amount, the collar 35a of the collet 35 passes through the flexible disk 52 to the receiving surface 12a provided at the top of the hub receiver 12.
Since the collet pushing spring 48 starts to displace at the same time, the outer periphery of the pusher ring 47 comes into contact with the tapered part 35b provided on the inner periphery of the collet 35, and since it descends while being pressed, a plurality of has a slit,
The center hole chuck portion 35c of the collet 35, which is shaped like a petal, has a slightly larger diameter.

It comes into close contact with the center hole 52a and completes the centering of the flexible disk 52. Thereafter, the pusher ring 47 is further lowered, and the collet pushing spring 4
The pressing force is transmitted to the collar portion 35a via the flexible disk 52, and as a result, the periphery of the center hole 52a of the flexible disk 52 is pressed and held between the receiving surfaces 12a. Said cholera! - At the same time as the push spring 33a, the head load arm 33b also descends, bringing the second magnetic head 25 into contact with the flexible disk 52 via the head arm 22. Since the first magnetic head 20 is arranged on the lower surface of the flexible disk 52, the flexible disk 52 is held between the first magnetic head 2o and the second magnetic head 25, and
An appropriate clamping force is applied by the head pressing spring 26. The state is shown in FIG. Thereafter, the drive motor 2 is rotated and the lapping motor 29 is rotated step by step in response to instruction signals from the host system, and signals are exchanged.

A chucking structure according to an embodiment of the present invention is shown in each figure other than FIG. 1 and FIG. 7, FIG. 8, and FIG. 9. The first feature of this embodiment is the collar portion 35a of the collet 35 and the receiving surface 12a of the hub receiver 12, which are shaped so that they cooperate with each other to warp the flexible disc 52 toward the upper side of the chassis. It is. The second feature is that the jacket receiving surface protrudes from the bottom surface of the chassis 1, and the height of the jacket receiving surface 1a is lower than the signal transfer surface 25a of the first magnetic head 25 by at least the thickness of the jacket 53.

A method for warping the flexible disk 52 toward the chassis 1 will be described below. As shown in Figures 10 and 11,
The diameter of the receiving surface 12a of the hub receiver 12 is made smaller than the diameter of the collar 35a of the collet 35, and the collar 35 is placed around the center hole 52a of the flexible disk 52.
If a pressing force is applied at point a, the flexible disk 52, which has extremely low rigidity in the thickness direction, will easily warp toward the chassis 1.

Furthermore, the flexible disk 52 is actively attached to the chassis 1.
Other methods of warping to the side are shown in Figures 12, 13 and 1.
Shown in Figure 4.

The receiving surface 12a in FIG. 12 is lowered from the center toward the outer periphery, and the collet 35 is aligned with the slope.
The flange portion 35a is also sloped.

The flexible disk 52 pressed and held between the hub receiver 12 and the collet 35 in this configuration is warped toward the chassis 1 side.

In the method shown in FIG. 13, a minute protrusion 35d is provided toward the chassis 1 side by the collar 35a of the collet 35 at a position with a larger diameter than the outer periphery of the receiving surface 12a of the hub receiver 12. The flexible disk 52 pressed and held by the above-mentioned minute protrusion 35d is forcibly bent toward the chassis 1 side.

FIG. 14 shows a method similar to that shown in FIG. 13, except that a small slope 35e is provided in place of the small protrusion 35d.

The small wi 54 occurs in the flexible disk 52 warped toward the chassis 1 as described above, as in the conventional case.

In the present invention, by providing the jacket receiving surface 1a as described above, the flexible disk 52 comes into pressure contact with the inside of the jacket 53 by its own warping force. The jacket receiving surface 1a is preferably installed near the first magnetic head 20 and the second magnetic head 25. The reason is that rectification of the fine wrinkles 54 cannot be performed on the entire surface of the flexible disk 52;
This is because the flattened small fi 54 occurs at a different location.

Therefore, in order to smooth the area near the magnetic head, it is effective to provide a jacket receiving surface 1a near the magnetic head. In the present invention, it is important to provide a jacket receiving surface on the upstream side of the flexible disk with respect to the magnetic head. The jacket receiving surface may be provided on the downstream side in addition to the upstream side.

The height of the jacket receiving surface 1a should be lower than the height of the signal transmitting and receiving surface 20a of the first magnetic head 20 by the paper thickness of the jacket 23 or more in order for the flexible disk 52 to come into good contact with the signal transmitting and receiving surface 20a. It is valid.

On the other hand, if the jacket surface 1a is too high, the jacket 53 lifts the flexible disk 52 too much, and as a result, the contact between the signal exchange surface 20a and the flexible disk 52 may become unstable.

As is clear from the above description, since the flexible disk 52 chucked by the drive device of the present invention has an umbrella shape,
The signal transmitting/receiving surface 20a is located closer to the chassis than the receiving surface 1.2a, so that the magnetic head and flexible disk 5
2 contact will be stable.

[Effects of the Invention] According to the present invention, it is possible to stably send and receive high-performance signal information, and the configuration is simplified, so that it is possible to obtain a magnetic disk drive device that is highly reliable and excellent in economic efficiency. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a front view of the embodiment device, FIG. 2 is a front view of the device, and FIG. 3 is a cross-sectional view of the same, showing a state in which no magnetic disk is inserted. FIG. 4 is a cross-sectional view of the same, and FIG. 5 is a vertical cross-sectional view, showing a state in which a magnetic disk is inserted. FIG. 6 shows an exploded perspective view of the chucking mechanism. 7th
The figure shows a partial view of a conventional chucking mechanism. 8 and 9 show the deformed state of the flexible disk. FIGS. 10 to 14 show cross-sectional views of a part of the chucking mechanism according to the present invention. FIG. 15 is a schematic perspective view of the magnetic disk. The first ρS (A) and (B) are characteristic diagrams comparing and showing the performance of the conventional device and the device of the present invention. [Explanation of symbols] 1...Chassis, 2...Drive motor, 12...
- Hub holder, 19... Carriage, 20... First magnetic head, 22... Head arm, 25... Second magnetic head. 26... Head pressing spring, 32... Top plate, 33...
Leaf spring, 33a... Collet push spring, 33b...
Head load arm, 35...collet, 39...
Return spring, 40... Collet plate, 41-... Collet shaft, 44-... Sleeve, 45... Ball bearing, 46... C ring, 47... Pressure ring, 48... Collet pusher. Spring, 51... Magnetic disk, 52... Flexible disk, 52a... Center hole, 53... Jacket.

Claims (1)

[Claims] 1. Consists of a magnetic head device for writing to and reading from a magnetic disk, a drive motor for driving the magnetic disk, a hub support rotated by the drive motor, and a collet having a pressing mechanism, the collet for the hub support. The device is equipped with a chucking device that presses and clamps the inner circumferential portion of the flexible disk exposed from the jacket by pressing the magnetic head device and a chassis that supports the magnetic head device and the chucking device. This magnetic disk drive device is characterized in that the flexible disk is provided with a means for warping in the pressing direction of the collet and deforming it into an umbrella shape, thereby warping the flexible disk in the pressing direction of the collet and supporting the jacket from the chassis side. 2. The magnetic disk drive device according to claim 1, further comprising a jacket receiving surface on the chassis that supports the jacket housing the flexible disk from a direction opposite to the direction in which the flexible disk is warped. 3. A magnetic disk drive device according to claim 1, wherein the jacket receiving surface has a predetermined width and a shape extending in the radial direction. 4. A magnetic disk drive device according to claim 1, wherein the flexible disk chucking device is provided with a mechanism that applies a bending action to the center hole portion of the flexible disk toward the chassis side. 5. A magnetic disk drive device according to claim 4, wherein the outer diameter of the collar portion of the collet that presses the flexible disk is made larger than the outer diameter of the receiving surface that presses the flexible disk of the hub receiver. 6. In claim 4, the pressing surface of the flange that presses the flexible disk of the collet is made to protrude in the pressing direction of the collet on the outer periphery of the flange, and the receiving surface that presses the flexible disk of the hub holder is recessed in the same direction. A magnetic disk drive device characterized by: 7. A magnetic disk drive device according to any one of claims 1 to 6, characterized in that the jacket receiving surface is provided at least upstream of the information exchange section by the magnetic head in the rotating direction of the flexible disk. 8. A magnetic disk drive device according to any one of claims 1 to 6, characterized in that the jacket receiving surfaces are provided on the upstream and downstream sides of the information exchange section by the magnetic head in the rotating direction of the flexible disk. 9. Claims 1 to 8 are characterized in that the position of the jacket receiving surface relative to the position of the signal transmitting and receiving surface of the magnetic head is moved in the warping direction of the flexible disk within a range of dimensions corresponding to the thickness of the jacket. Magnetic disk drive. 10. The magnetic disk drive device according to claim 1, wherein the position of the jacket receiving surface relative to the position of the flexible disk receiving surface of the hub is moved in the direction of warpage of the flexible disk. 11. A magnetic disk drive device according to any one of claims 1 to 8, characterized in that the position of the jacket receiving surface is moved in a direction opposite to the warping direction of the flexible disk with respect to the position of the flexible disk receiving surface of the hub. 12. Claims 1 to 8 are characterized in that the position of the information exchange surface of the magnetic head is moved in the opposite direction to the warping direction of the flexible disk with respect to the position of the flexible disk receiving surface of the hub and the position of the jacket receiving surface. magnetic disk drive device. 13. A magnetic head drive device according to any one of claims 1 to 8, characterized in that the difference between the position of the jacket receiving surface and the position of the information exchange surface of the magnetic head is equal to or smaller than the thickness of the jacket. .