JPS6180548A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To improve the reliability of magnetic recording/reproduction by providing a roller to a cassette guide side via a plate spring, and pressing the roller to the boss of a magnetic disc. CONSTITUTION:One end of a plate spring 74 is fixed to the upper face of a cassette guide 67 and the tip of the plate spring 74 is prolonged between two long holes 67b, 67b formed to the center of the cassette guide 67. The long holes 67b are formed in the same direction as the loading/ejecting direction of a magnetic disc cassette 68, and a roller 75 fitted in the long holes 67b is provided to the tip of the plate spring 74. The roller 75 is in contact with the upper face of a boss 54 of the magnetic disc positioned to the lower part of the long hole 67b and the force of the plate spring 74 presses the boss 54 to a cup shaped member 51 incorporated with a motor shaft 50. Thus, it is possible to prevent any slip in cooperation with the adsorbing force of the magnet 52 when the magnetic disc rotates.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device in which a magnetic head is placed in contact with or facing a rotating magnetic disk to write and read information. It is.

[Prior Art] Magnetic disk devices that perform magnetic recording and reproduction by bringing a magnetic head into contact with or facing a rotating magnetic disk are widely used.

Although so-called floppy disk devices are widely used as such magnetic disk devices, still video cameras and the like have recently been put into practical use.

In such a magnetic disk device, accurate recording and reproduction cannot be performed unless the magnetic disk rotates with the magnetic head always in close contact with or facing the magnetic disk.

Therefore, conventionally, a structure has been proposed in which the magnetic disk is reliably chaffed to prevent the magnetic disk from slipping, and the magnetic disk is pressed toward the magnetic head via a pad.

However, the conventional chucking structure is extremely complicated.
The large size hinders miniaturization of the device and has the disadvantage of increasing costs.

[Objective] The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and provides a magnetic disk device configured to reliably hold and rotate a magnetic disk with an extremely simple structure. is intended to provide.

Embodiments] The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 and the following are explanations of one embodiment of the present invention, and the illustrated embodiment is an example in which two magnetic disk cassettes are installed, but it is of course possible to use only one.

When this type of magnetic disk device is used in conjunction with a computer, it becomes a large-capacity storage device, and if important programs are stored on one magnetic disk, they are immediately copied and saved on the other magnetic disk. It is extremely advantageous because it can be done.

The magnetic disk device of this embodiment is assembled based on chassis 1, and broadly classified into chassis l.
Two sets of head moving mechanisms 2, 2 mounted on the top, a motor 3 provided on the bottom surface of the chassis 1, and a cassette mounting mechanism provided on the chassis 1 so as to cover the head moving mechanism 2.2. It consists of 4,4.

The details of each part will be explained in order below.

As shown in FIGS. 7 and 8, the head moving mechanism 2
It has a guide 5 fixed on the chassis 1, and a slider 6 slidably attached to cover the guide 5 from above to both left and right sides.

Two guide bars 7 each having a circular cross section are provided at opposing positions on both sides of the guide 5 and on the inner side of the U-shaped slider 6.
A plurality of steel poles 8 are arranged in contact with guide bars 7, each of which has a total of four pieces.

Therefore, the guide bar 7 and the steel pole 8 are in point contact at four locations, and the slider 6 is hardly affected by frictional force and can move extremely smoothly.

Furthermore, if there is play between the guide bar 7 and the steel pole 8, the slider 6 cannot be linearly interlocked with high precision.
is pressed against the steel pole 8 to remove looseness.

Although not shown, the slider 6 is pressed by a spring in a direction toward a pulse motor 11, which will be described later.

On the other hand, one end of a head arm 12 is fixed to the slider 6, and the head arm 12 extends bent along one side of the slider 6, is guided along the upper surface of the chassis l, and is attached to the upper surface of its tip. A magnetic head 14 is fixed via a head stand 13.

The head stand 13 is fixed via screws 15, but screws 1
The hole into which 5 is fitted is a long hole 13a extending along the longitudinal direction of the head stand 13, and a disc spring 16 is elastically loaded between the screw 15 and the head stand 13. The backlash is removed.

Further, a torsion coil and a spring 17 are attached to the upper surface of the head arm 12 near the head stand 13.
One end is in contact with the pin 18 on the helad arm 12, and the other end is in contact with the side surface of the head stand 13, pressing the head stand 13 toward the tip of the head arm 12.

A bent portion 12a is formed at the tip of the head arm 12, and a screw 19 is screwed into the bent portion 12a. The tip of the screw 19 is in contact with the side surface of the head stand 13 on the opposite side from the torsion coil spring 17.

Therefore, by turning the screw 19 to move it back and forth, the position of the magnetic head 14 is adjusted in cooperation with the force of the torsion coil spring 17, and the deviation 1 between a straight line passing through the motor axis and the center of the magnetic head, which will be described later, is reduced to zero. It can be done.

On the other hand, one end of an adjustment plate 20 is fixed to the upper surface of the slider 6 above the head arm 12. Adjustment plate 20
The other end is bent along the bent shape of the helad arm 12, and its tip extends halfway down the helad arm 12.

A screw 21 is screwed into the tip of this adjustment plate 20,
The lower end of this screw 21 is in contact with the upper surface of the helad arm 12. Therefore, by rotating the screw 21, the screw 21 can be moved up and down, and the vertical position of the magnetic head 14 can be adjusted via the head arm 12.

Note that side plates 2 are provided at both ends of the slider 6 as shown in FIG.
2 and 23 are fixed.

On the other hand, at a position away from the slider 6, the chassis 1
A support plate 24 is fixed above in parallel with the side plates 22, 23, and the pulse motor 11 is fixed to the support plate 24. A pinion gear 25 is fixed to the output shaft 24a of the pulse motor 24.

Further, as shown in FIG. 8, a threaded cylinder 26 is fixed to the support plate 24 in line with the pulse motor 11.
A screw shaft 27 is screwed into the.

Two gears 2 are connected to the outer end of the screw shaft 27 via a boss z8.
9.30 is installed. These gears 29 and 30 are meshed with the pinion gear 25, but one gear 29
is fixed to the post 28, and the other gear 30 is rotatable.

An opening 30a is formed in the rotatable gear 30, and a pin 31 protruding from the side surface of the gear 29 is fitted into the opening 30a. A spring 33 is stretched between this pin 31 and a pin 32 protruding from the outer surface of the gear 30, and applies a force to rotate the gear 30 clockwise in FIG. 9.

Therefore, the teeth of the gears 29, 30 tend to deviate from each other, but when the gears 29, 30 mesh with the pinion gear 25, the teeth are forced into alignment, and the force that tends to deviate serves to prevent backlash. fulfill.

Note that a pin 34 is provided protruding from the end surface of the post 28 on the support plate 24 side.

The inner end of the screw shaft 27 is in contact with the outer surface of an adjusting screw 35 that is threaded onto the outer surface of the side plate 22 .

Therefore, when the pulse motor 11 is rotated, the gear 29.
The screw shaft 27 moves back and forth via the slider 6 and the head arm 12, and the magnetic head 14 is moved in the diametrical direction of the magnetic disk via the slider 6 and the head arm 12, thereby performing head movement.

On the other hand, a shaft 36 is protruded from the outer surface of the support plate 24 in the vicinity of the screw shaft 27, and a shirt shirt plate 37 is rotatably supported at one end of the shaft 36 via a boss 378L. There is.

A spring piece 38 is provided above the end of the shirt cover plate 37 on the boss 37a side, and the tip of the spring piece 38 is connected to the outer surface of the support plate 24 and to the pin 3 protruding above the screw shaft 27.
9, and gives the shirt shirt plate 37 the ability to rotate in the clockwise direction in FIG.

However, the limit of clockwise rotation of the shirt flap plate 37 is restricted by the lower end 37b of the shirt flap plate 37 coming into contact with a pin 40 protruding from the support plate 24.

Furthermore, openings 41 and 42 are formed at positions that can match the shear plate 37 and the support plate 24. Support plate 2
A photosensor 43 consisting of a light emitting element and a light receiving element is provided on the back side of the opening 42 of No.4.

This shutter plate 37 constitutes a pulse generating means (TR"OO" detection mechanism) for detecting that the magnetic head has reached the outermost track position of the magnetic disk and generating a pulse.

On the other hand, each head moving mechanism 2.2 is attached to the chassis l.
An eject lever 44 is provided correspondingly.

The eject lever 44 is formed into an elongated plate shape,
Elongated holes 44a are formed along the axial direction at the front and rear.

Pins 45 and 46 protruding from the chassis l are slidably fitted into the elongated holes 44a, respectively.

An eject button 47 is fixed to the front side of the eject lever 44.

A spring 48 is stretched between the pin 46 near the eject button 47 and the bent portion 44b at the tip of the eject lever 44, and the eject lever 44 has a tendency to move to the right in FIG. Usually, the pins 45 and 46 are in contact with the left ends of the long holes 44a and 44a.

Eject lever 44 is provided with an upright cam 49 located between pins 45,46.

This cam 49 has a slope 49a on the eject button 47 side.
is formed.

This eject lever 44 performs a cassette ejection operation in conjunction with a cassette mounting mechanism 4.4, which will be described later.

In addition, each head movement mechanism 2.2 is mounted on the chassis l.
A motor shaft 5o is provided in a protruding state corresponding to the above.

This motor shaft 50 is a cup-shaped member 5 with an open upper end.
1 integrally.

The height of this cup-shaped member 51 is lower than the height of the motor shaft 5°, and is made of a non-magnetic material.

A ring-shaped magnet 52 is fixed to the bottom surface of the cup-shaped member 51.

The reason for providing such a magnet 52 is as follows.

That is, as shown in FIG. 6, the magnetic disk 53 has a post (made of synthetic resin) fitted to the motor shaft 5o at its center.
54, and this post 54 and a washer 5 made of a magnetic material.
The central portion of the magnetic disk 53 is sandwiched and fixed between the two magnetic disks 5 and 5.

Therefore, when the magnetic disk cassette is installed and the motor shaft 5o is fitted into the post 54 as described later, the magnetic flux of the magnet 52 is guided through the vicinity of the cup-shaped member 51, which is made of a magnetic material. The washer 55 can be attracted by magnetic force.

Therefore, the rotational force of the motor can be reliably transmitted to the magnetic disk side without any slip occurring between the motor shaft 50 and the post 54.

The motor shaft 50 is rotatably attached to the chassis l via a disc-shaped bearing 56.

Further, a disc 57 is fixed to the lower end of the motor shaft 50 on the lower side of the chassis l.

This disk 57 is fixed to a rotor 58. The rotor 58 has a ring-shaped magnet 59 and a signal generating gear 6o for rotation control.

One end of a belt 61 is wrapped around the rotor 58, and the other end is wrapped around the rotor 62 of the other motor shaft 5o.

The bell) 61 is in contact with the tension roller 63 to prevent unstable rotation due to deflection.

On the other hand, a printed circuit board 64 is fixed to the lower surface of the chassis l, surrounding the motor shaft 5o.

A coil 6 formed in a ring shape on this printed circuit board 64
5 is fixed and faces the magnet 59 of the rotor 58.

Therefore, when the coil 65 is energized, a magnetomotive force is generated and the a-coil 58 is rotated via the magnet 59.

When the rotor 58 rotates, the rotor 62
can rotate and also rotate the other motor shaft.

The rotor 58 and coil 65 described above constitute the motor 3.

On the other hand, the cassette mounting mechanism 4 is constructed as shown in FIGS. 2 to 4.

That is, the cassette mounting mechanism 4 has a rotating frame 66, and bent portions 66a formed at both ends of the rotating frame 66 on the back side.
The head movement of chassis l is 43! It is rotatably supported on bent portions 1a and 1a provided near the structure 2, respectively.

A cassette guide 67 formed as a flat frame body is slidably attached to the rotating frame 66.

A magnetic disk cassette 68 is inserted into this cassette guide 67.
are slidably fitted.

A large opening is provided below the cassette guide 67 so that the magnetic head, motor shaft, etc. can be freely accessed.

On the other hand, a lever 69 having an L-shaped cross section is slidably in contact with the side edge of the cassette guide 67.

An elongated opening 69a is formed at a corner of the lever 69 over a predetermined length, and a protruding piece 67a cut and raised from the cassette guide 67 is fitted into this opening 69a.

Two elongated holes 69b are formed in the vertical part of the lever 69 along the longitudinal direction of the lever 69, and a pin 70 protruding from the cassette guide 67 is slidably fitted into these elongated holes. has been done.

Further, a pin 71 is protruded from the vertical portion of the lever 69 and engages with a protrusion tb protruding from the chassis l at a position closer to the cassette insertion opening side.

Further, a spring 72 is stretched between a bent portion 69c protruding from the end of the lever 69 opposite to the pin 71 and a protruding piece 67a of the cassette guide 67.
is always given a force that draws it toward the cassette insertion slot.

Further, a spring 7 is provided between the protruding piece 67a and the chassis l.
3 is stretched, and the entire rotating frame 66 including the cassette guide 67 is drawn toward the chassis 1 side.

Further, a bent portion 69d is formed at the tip of the lever 69, and this bent portion 69d engages with the tip of the magnetic disk cassette 68 as described later.

By the way, one end of a leaf spring 74 is fixed to the upper surface of the cassette guide 67, and the tips of the leaf spring 74 are connected to two long holes 67b formed in the center of the cassette guide 67,
It extends to between 67b and 67b.

These elongated holes 67b are formed in the same direction as the direction in which the magnetic disk cassette 68 is installed and removed.

A roller 75 that fits into the elongated hole 67b is provided at the tip of the leaf spring 74.

As shown in FIG. 5, this roller 75 contacts the upper surface of the magnetic disk post 54 located below the elongated hole 67b, and the force of the leaf spring 74 causes the post 54 to be attached to the cup-shaped member 51 integrated with the motor shaft 50. It's forcing me.

Therefore, in cooperation with the attraction force of the magnet 52, slippage is prevented when the magnetic disk rotates.

Further, an opening 76 is formed near the elongated hole 67b.

This opening 76 has a PG pin (
An index pin) 77 is faced, and a sensor 78 is faced from above.

The sensor 78 is connected to a printed circuit board 79 fixed on the cassette guide 67, and is equipped with a magnetoresistive element (MR).
It consists of elements such as

The magnetic flux of the magnet 52 is guided to the PC pin 77 via the cup-shaped member 51, and a weak magnetic field is induced.

Although this magnetic field is extremely weak, the MR element's sensor 78 detects it, and the internal resistance value changes.The resistance change is used to create a pulse using a comparator, etc., and one pulse is generated with one rotation of the magnetic disk. Used for index signal.

Furthermore, since the MR element is sensitive to extremely weak magnetic fields, if the device of this embodiment is attached to a personal computer or the like, there is a risk of malfunction due to changes in the magnetic flux generated around the CRT, the transformer, and the motor.

Therefore, in this embodiment, the cassette guide 67 is made of an iron-based material with a large magnetic shielding effect to prevent malfunction.

Furthermore, considering the magnetic shielding effect, the smaller the size of the opening 76, the better; however, in this embodiment, an index detection mechanism using an MR element is adopted, so as shown in FIG. 5(A).
As shown in the figure, the size could be made to be almost within the size of the post 54, which has a diameter of 10 to 15 square centimeters.

Furthermore, since the MR element can detect changes in the magnetic field without regard to the rate of change in magnetic flux, it is ideal as a small-sized, high-speed index detection device.

Note that there is a pad lever 80 on the back side of the cassette guide 67.
One end is rotatably attached, and a pad 81 provided on the lower surface of the free end passes through an opening 82 of the cassette guide 67 and presses the magnetic disk 53 from above at a position corresponding to the magnetic head. The disk and the magnetic helad can be brought into reliable contact.

Note that since the pad 81 is fixed to a screw 83 attached to the tip of the pad lever 80, the contact pressure of the pad 81 against the magnetic disk 53 can be adjusted by turning the screw 83.

On the other hand, the magnetic disk cassette 68 is shown in FIGS.
It is configured as shown in C).

The magnetic disk cassette 68 is a flat case made of two upper and lower cassette halves 84 made of hard synthetic resin, etc., and the magnetic disk 53 is rotatably housed in the case via a post 54. There is.

Further, each of the cassette halves 84 is formed with an opening 68a at an opposing position into which a magnetic head or a pad is inserted.

Further, a shutter 85 for preventing dust from entering through the opening 68a is slidably fitted into the recess 86 including the opening 68a.

This shutter 85 has one end 86a and the other end 86b of the recess 86.
The opening 68a can be freely moved to a position where it comes into contact with the opening 68a.
Open and close.

This shutter 85 is automatically opened and closed using the operation of inserting and removing the cassette into the cassette guide 67, and its opening and closing mechanism is shown in FIGS. 16(A) and 16(B).

That is, the opening/closing lever 8 is opened at a position opposite to the side edge of the cassette guide 67 where the lever 69 is provided.
One end of 7 is rotatably supported by a protrusion 89 on the cassette guide 67 side via a pin 88.

A torsion coil spring 90 is wound around the pin 88.
The opening/closing lever 87 is provided with the ability to rotate clockwise in FIG.

On the free end side of the opening/closing lever 87, there are first and second protrusions 87a, 8 which act as stoppers toward the cassette guide 67 side.
7b is provided protrudingly.

The first protrusion 87a has a slope 87c formed at its distal end so that the cassette insertion port side is lowered, and the rear end thereof is an upright wall 87d.

On the other hand, a protrusion 91 protrudes from the inside of the cassette guide 67, and an opening 92 into which the protrusion 87a of the opening/closing lever 87 fits is formed at a position closer to the cassette insertion opening than the protrusion 91. .

Next, a shutter 85 of the cassette configured as one or more
Explain the operation of the opening/closing mechanism.

17(A) to 17(D) illustrate the operation of opening the shutter, and as shown in FIG. 17(A), the cassette 68 is inserted into the cassette guide 67 with the shutter 85 closed. Then, the tip of the first protrusion 87a of the opening/closing lever 87 comes into contact with the edge of the shutter 85, and soon the tip of the first protrusion 87a rides on the side surface of the shutter 85 as shown in FIG.

When the cassette 68 is further pushed in in this state, the edge of the shutter 85 comes into contact with the protrusion 91 as shown in FIG. It fits into the shutter 85 from the portion 85a.

When the cassette 68 is further pushed in, only the shutter 85 remains because the shutter 85 is blocked in that position by the protrusion 91.
will be held.

On the other hand, the operation of closing the shutter 85 is shown in FIGS.
).

FIG. 18(A) shows the state in which the cassette is installed. When the cassette starts to be ejected from this state by the operation described later, the shutter 8 is opened as shown in Fig. 18CB).
Since the edge of the opening 85a of the shutter 8 is in contact with the upright wall 87d of the first protrusion 87a of the opening/closing lever 87, the shutter 8
5 remains in that position and only the cassette 68 is moved in the direction of ejection.

Then, the cassette temporarily stops in the state shown in FIG. 18 CB).

At this time, the tip of the cassette 68 has protruded a predetermined distance from the cassette guide lower, so if you pick it up with your fingers and pull it out, the opening/closing lever 87 cannot resist the strong force, as shown in Fig. 18 (C).
), the cassette 6 is forcibly rotated about the pin 88 in the counterclockwise direction in the figure, and the shutter is closed.
8 can be taken out.

By the way, the overall operation of the apparatus of this embodiment configured as above will be explained.

When the power is turned on, current flows through the coil 65 and the rotor 58.
rotates, and the motor shaft 50 rotates.

In this state, the cassette 68 can be attached to any of the cassette guides 67. Before the cassette 68 is installed, the eject lever 44 is moved by the spring 48.
The slope 49a of the protrusion 49 is moved forward by pushing against the tensile force of
0 to position the pin 70 above the protrusion 49.

Then, the cassette guide 67 is lifted into an inclined state together with the rotating frame 66.

At this time, as shown in FIG. 4(A), the pin 71 is in a state riding on the protrusion lb on the chassis 1 side, and the lever 6
9 is pulled toward the front side by the tensile force of the spring 72, and the pin 71 is pressed onto the projection lb by the tensile force of the spring 73.

Therefore, even if the eject lever 44 is released, the cassette guide 67 does not descend.

That is, when the front side of the cassette guide 67 is lifted up, the cassette insertion slot is set in the standby state.

When the cassette 68 is inserted into the cassette guide 67 in this state, the shutter 85 is automatically opened and the cassette is inserted as described above.

On the other hand, as the cassette 68 is inserted, the tip of the cassette comes into contact with the bent portion 69d at the tip of the lever 69.
is pushed together with the cassette 68.

As a result, the spring 72 is extended so that the pin 70 is in the elongated hole 69b.
As shown in FIG. 3(A), the pin 71 is removed from the protrusion 1b and comes into contact with the inner side edge of the protrusion 1b.

That is, the cassette guide 67 is lowered together with the cassette 68, and the post 54 is fitted onto the motor shaft 50.

At the same time, the tip of the pad lever 80 descends, and the magnetic pad 1
4 through the magnetic disk 53.

In this state, the rotation of the magnetic head is started and the sensor 78 and P
Index detection is performed by the G pin 77, and the rotation of the pulse motor 11 operates the head moving mechanism 2 to move the head.

When a ten-phase pulse is applied to the pulse motor 11, its output shaft 24a is rotated clockwise in FIG. 9, and when a -phase pulse is applied, the output shaft 24a is rotated counterclockwise.

Here, when the gears 29.30 are rotated clockwise in FIG. 9 via the pinion gear 25, the screw shaft 27 is also rotated in the same direction, and the gears 29.30 are moved in the direction of the shutter plate 37.

If gear 29.30 is rotated counterclockwise, gear 29.
30 is separated from the shirt top plate 37.

Now, when the gears 29 and 30 rotate clockwise in FIG.
4 begins to touch the lower edge of the shirt shirt plate 37 as shown in FIG.

Then, the shirt shirt plate 37 is rotated about the shaft 36 in the counterclockwise direction in FIG.

Since the opening 41 of the shirt flap plate 37 normally does not coincide with the opening 42 of the support plate 24, the light from the light emitting element of the sensor 43 hits the shirt flap plate 37, is reflected, is detected by the light receiving element, and the sensor 43 is turned on. It is in a state.

However, the gears 29 and 30 move in the direction of the shirt flap plate 37 from the state shown in FIG. When rotated counterclockwise in Fig. 11, the 12th
As shown in the figure, light from the light emitting element of the resensor 43 with the openings 41 and 42 aligned passes through and does not return to the light receiving element. Therefore, sensor 43 is turned off.

At this time, the magnetic helad 14 has reached the outermost circumference of the track.

Distance from the center of the magnetic disk to the outermost track 11L
If 20g is used as a proverb, then the magnetic head is located at the outermost periphery of the track, 20 layers away from the center.

However, due to variations in component precision, even if the opening 41 of the shirt shirt plate 37 and the opening 42 of the support plate 24 match,
= 20mm The magnetic head is not necessarily located in the state.

Then, turn the screw 35 that the tip of the screw shaft 27 touches, and
= 205m.

The adjustment method is to first open the opening 41.4 as shown in Figure 12.
2 match, the sensor 43 is turned off, and the screw 35 is rotated so that the distance from the center of the motor shaft 50 to the magnetic head 14 is 20 mm using a microscope as shown in FIG. good.

Then, when L=20+am, the screw 35 is locked using adhesive or the like.

According to the inventor's experiments, the pitch of the screw 35 is Q, 3m
By setting the length to m, the adjustment of about ±24 m for L=20 mm was sufficient.

Note that since the thread pitch of the screw shaft 27 is set to 0.5 mm, the pin 34 is in contact with the lower edge of the shirt flap plate 37 as shown in FIG. When the screw shaft 27 rotates once in the clockwise direction, the pin 34 separates from the shirt flap plate 37 as shown in FIG. 10(C).

That is, during the period from the state shown in FIG. 1θ (A) to the state shown in FIG. Yes, otherwise sensor 43
It never turns off.

Incidentally, while rotating the shirt flap plate 37 from the state shown in FIG. 11 to the state shown in FIG. 12, the screw 27 rotates by .beta.:9'', and the sensor 43 is turned off.

When the screw shaft 27 rotates 9 degrees, the pin 34 moves in an arc shape of approximately 0.0 degrees.
4■ Move.

Further, the width of the openings 41 and 42 is set to 1.2 mm.

Therefore, in this embodiment, from the center of the shaft 36 to the pin 34
The distance from the center of the pin 36 to the point where the pins touch the opening 4
1/3 of the distance to 1.42, and 0.4m of pin 34
The displacement of m is expanded to 1.2H using the rotation of the shutter 37, and the openings 41 and 42 through which the light from the sensor 43 passes are enlarged to improve efficiency.

Generally, when using an optical sensor, it is better to guide the amount of light from the light emitting element to the light receiving element as efficiently as possible, and the larger the opening through which the light from the sensor 43 passes, the better.

Further, in order to turn off the sensor 43 and to prevent all the light from the light emitting element from returning to the light receiving element, it is better to have a larger opening.

For this purpose, the slight rotation angle of 9 degrees of the screw shaft 27 was expanded using the lever ratio of the shutter plate 37 to improve the efficiency of the sensor.

On the other hand, FIG. 13 shows a state in which the screw shaft 27 has been further rotated by 9 degrees from the state shown in FIG. 12.

In this state, α=18. Then, the sensor 43 is turned on, and it is possible to detect that the magnetic head 14 has protruded beyond L = 20 mm, and a signal can be obtained to reverse the pulse motor 11 and return it to its normal position.

In this way, magnetic recording and reproduction can be performed while accurately determining the outermost track position.

On the other hand, if you want to remove the cassette after magnetic recording and playback is finished, press the eject lever 4 via the eject button 47.
When you press 4, the eject lever protrusion 49 will open as mentioned above.
The cassette guide 67 is lifted up via the pin 70. This state is the state shown in FIG. 4(A) described above.

At this time, the lever 69 returns due to the force of the spring 72, so that the recassette 68 is pulled out by the bent portion 69d of the lever 69.

Although this distance that is pulled out is small, the cassette 68
protrudes from the cassette guide 67, and the cassette can be easily pulled out by pinching this protrusion with fingers.

At this time of withdrawal, the shutter 85 is automatically closed as described above.

In addition, in the above example, is the head moving mechanism? Although the present invention is not limited to this example, only one head moving mechanism 2 may be provided as shown in FIG. 14.

To adopt such a modification, the helad arm should be 12.
12a are integrally formed, each with a magnetic helad 1
4 should be installed.

[Effects] As is clear from the above description, according to the present invention, a roller is provided on the cassette guide side via a leaf spring, and this roller is pressed against the boss of the magnetic disk. Therefore, the magnetic disk can be reliably held on the motor shaft side, and slippage of the magnetic disk does not occur, and reliability of magnetic recording and reproduction can be improved.

[Brief explanation of the drawing]

The figures are for explaining one embodiment of the present invention. Figure 1 is an overall perspective view, Figure 2 is an exploded perspective view, and Figures 3 (A) and CB) are views of the cassette guide and eject lever when the cassette is installed. 4(A), CB) are partially longitudinal side views of the cassette guide and eject lever during cassette ejection, and FIG. 5(A), CB) are plan views of the magnetic disk holding mechanism. FIG. 6 is a vertical side view of the main parts of the magnetic disk drive mechanism; FIG. 7 is a vertical side view of the head moving mechanism; FIG. 8 is a plan view of the head moving mechanism; The figure is an exploded perspective view of the track outermost circumference detection mechanism, FIGS. 10(A) to (C) are plan views explaining the operation of the track outermost circumference detection mechanism, and FIGS.
Figure 13 is a front view illustrating the operation of the shirt top plate;
The figure is a plan view illustrating a modified example of the head moving mechanism.
Figures (A) to (C) are a plan view, front view, and vertical side view of the magnetic disk cassette, Figures 16 (A) and (B) are an exploded perspective view and a plan view illustrating the shutter opening/closing mechanism, and Figure 17. (A) to (D) are plan views explaining the shutter opening operation;
FIGS. 18(A) to 18(C) are plan views illustrating the operation of closing the shutter. 1... Chassis 2... Head moving mechanism 3.
...Motor 4...Cassette mounting mechanism 6...
・Slider 11...Pulse motor 14...
Magnetic head 19, 21.35...screw 27...
Screw shaft 43...Sensor 44...Eject lever 50...Motor shaft 58...Rotor 65...
Coil 66...Rotating frame 67...Cassette guide 68...Magnetic disk cassette 69...Lever 70.71...Bin 74...
...Plate spring 78...Sensor Fig. 10 (A) Fig. 11, Fig. 12 Fig. 13 Fig. 14 Fig. 15 (A) Fig. 16 (B) Fig. 17 (A) Fig. 17 ( B) Figure 18 (A)

Claims (1)

[Claims] In a magnetic disk device that rotates a magnetic disk by fitting a boss of the magnetic disk to a motor shaft via a cassette guide into which a magnetic disk cassette is attached, a roller that can rotate along the direction of attaching and detaching the magnetic disk is provided on the cassette guide side. 1. A magnetic disk device, characterized in that the roller is provided via a plate spring so as to be able to press the boss of the magnetic disk.