JPH0570228B2 - - Google Patents

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 are widely used in which a magnetic head is brought into contact with or faces a rotating magnetic disk to perform magnetic recording and reproduction.

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, a head moving mechanism is provided on two parallel guide shafts, and a structure is adopted in which the head moving mechanism is driven by the rotational force of a pulse motor via a metal belt.

When such a structure is adopted, a large frictional force acts between the head moving mechanism and the guide shaft, and the driving force of the pulse motor must be increased.
The drawbacks were that the device was large and required a large amount of power.

[Purpose] The present invention has been made to eliminate the above-mentioned drawbacks of the conventional technology, and provides a compact pulse motor with low power consumption that can drive a head moving mechanism with almost no sliding friction. It is an object of the present invention to provide a magnetic disk device configured so that it can be used.

[Example] The details of the present invention will be described below based on the example shown in the drawings.

FIG. 1 and the following are explanations of one embodiment of the present invention, and the illustrated embodiment is exemplified as one in which two magnetic disk cassettes are installed, but of course one may be used.

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

The magnetic disk device according to this embodiment has chassis 1.
The head moving mechanisms 2, 2 are assembled based on the standards, and can be broadly classified into two sets of head moving mechanisms 2, 2 mounted on the chassis 1, a motor 3 provided on the bottom surface of the chassis 1, and the head moving mechanisms 2, 2 mounted on the chassis 1. The cassette mounting mechanism 4 is provided on the chassis 1 so as to cover the cassette mounting mechanism 4.

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

As shown in FIGS. 7 and 8, the head moving mechanism 2 includes a guide 5 fixed on the chassis 1,
A slider 6 is 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 fixed to opposing positions on both sides of the guide 5 and on the inner side of the U-shaped slider 6, and the guide bars 7 are in contact with a total of four guide bars 7. A plurality of steel balls 8 are arranged in each state.

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

Furthermore, if there is play between the guide bar 7 and the steel ball 8, the slider 6 cannot move linearly with high precision, so the screw 10 is inserted through the plate 9.
The guide bar 7 is pressed against the steel ball 8 to remove backlash.

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 in a bent manner along one side of the slider 6.
It is guided along the upper surface, and a magnetic head 14 is fixed to the upper surface of the tip via a head stand 13.

The head stand 13 is fixed via a screw 15, and the hole into which the screw 15 fits is a long hole 13a along the longitudinal direction of the head stand 13.
A disc spring 16 is mounted between the head stand 13 and the head stand 13 to eliminate play in the vertical direction of the head stand 13.

In addition, a head stand 1 is mounted on the upper surface of the head arm 12.
A torsion coil spring 17 is attached near 3, one end of which touches the pin 18 on the head arm 12, the other end of which touches the side of the head stand 13, and presses the head stand 13 toward the tip of the head arm 12. There is.

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 l between the center of the magnetic head and a straight line passing through the motor shaft, 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. The other end of the adjusting plate 20 is bent along the curved shape of the head arm 12, and its tip extends halfway down the head arm 12.

A screw 21 is screwed into the tip of this adjustment plate 20, and the lower end of this screw 21 is connected to the head arm 12.
is in contact with the top surface of 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 22 and 23 are fixed to both ends of the slider 6, as shown in FIG.

On the other hand, at a position away from the slider 6, a support plate 24 is fixed on the chassis 1 in parallel with the side plates 22 and 23, and a 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 parallel with the pulse motor 11, and a screw shaft 27 is screwed into the threaded cylinder 26.

Two gears 29 and 30 are attached to the outer end of the screw shaft 27 via a boss 28. These gears 29 and 30 mesh with the pinion gear 25, but one gear 29 is fixed to the boss 28, and the other gear 30 is rotatable.

The rotatable gear 30 has an opening 30a.
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.
The force that tends to shift serves to prevent crashing.

Note that a pin 34 is provided protruding from the end surface of the boss 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 screw shaft 27 is moved back and forth via the gears 29 and 30, and the magnetic head 1 is rotated via the slider 6 and the head arm 12.
4 is moved in the diametrical direction of the magnetic disk to perform head movement.

On the other hand, a shaft 36 is provided protruding from the outer surface of the support plate 24 in the vicinity of the screw shaft 27.
A shutter plate 37 is rotatably supported on one end of the shutter plate 6 via a boss 37a.

A spring piece 38 is provided above the end of the shutter plate 37 on the boss 37a side, and its tip is located on the outer surface of the support plate 24 and below the pin 39 that projects above the screw shaft 27. It is in contact with the side and gives the shutter plate 37 the habit of rotating clockwise in FIG.

However, the limit of clockwise rotation of the shutter plate 37 is that the lower part 37b at the tip of the shutter plate 37 is located at the support plate 24.
It is regulated by coming into contact with a pin 40 protruding from.

Further, openings 41 and 42 are formed at positions that can match the shutter plate 37 and the support plate 24. A photo sensor 43 consisting of a light emitting element and a light receiving element is provided on the back side of the opening 42 of the support plate 24 .

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

On the other hand, the chassis 1 is provided with an eject lever 44 corresponding to each of the head moving mechanisms 2, 2.

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

Pins 45 and 46 protruding from the chassis 1 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 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. Usually, the pins 45 and 46 are connected to the long holes 44.
a, it is in contact with the left end of 44a.

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

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

This ejection lever 44 performs a cassette ejection operation in conjunction with cassette mounting mechanisms 4, 4, which will be described later.

Further, a motor shaft 50 is provided on the chassis 1 in a protruding state corresponding to each of the head moving mechanisms 2, 2.

The motor shaft 50 integrally includes a cup-shaped member 51 with an open upper end.

The height of this cup-shaped member 51 is the motor shaft 50.
It is made of 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.
3 has a boss (made of synthetic resin) 54 in its center that is fitted onto the motor shaft 50, and a magnetic disk 5 is placed between this boss 54 and a washer 55 made of a magnetic material.
3 is fixed in a pinched state.

Therefore, when the magnetic disk cassette is installed and the motor shaft 50 is fitted into the boss 54 as will be described later, the magnetic flux of the magnet 52 is guided through the vicinity of the cup-shaped member 51 and is removed from the 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 boss 54.

The motor shaft 50 is rotatably attached to the chassis 1 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 1.

This disk 57 is fixed to a rotor 58. The rotor 58 has a ring-shaped magnet 59 and a signal generating gear 60 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 50.

The belt 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 1 in a state surrounding the motor shaft 50.
A ring-shaped coil 65 is fixed to the printed circuit board 64 and faces the magnet 59 of the rotor 58.

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

When the rotor 58 rotates, the rotor 62 rotates via the belt 61, and the other motor shaft can also be rotated.

The rotor 58 and coil 65 described above are the motor 3
It consists of

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 the bent portions 66a formed at both ends of the rotating frame 66 on the back side are connected to the head moving mechanism 2 of the chassis 1.
It is rotatably supported on bent portions 1a, 1a provided near the .

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

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

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, the side edge of the cassette guide 67 has a cross section of L.
A lever 69 formed in a letter shape is in slidable contact.

An elongated opening 69a is formed at a corner of the lever 69 over a predetermined length.
A protruding piece 67a cut and raised from the cassette guide 67 is fitted into the cassette guide 9a.

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 1b protruding toward the chassis 1 at a position closer to the insertion opening of the cassette.

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

Further, a spring 73 is stretched between the protruding piece 67a and the chassis 1, and the cassette guide 6
The entire rotating frame 66 including the rotary frame 7 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 will be described later.

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

These long holes 67b are connected to the magnetic disk cassette 68.
It is formed in the same direction as the attachment/detachment direction.

The long hole 67b is located at the tip of the leaf spring 74.
A roller 75 is provided which fits therein.

This roller 75 has an elongated hole 67 as shown in FIG.
It is in contact with the upper surface of the boss 54 of the magnetic disk located below b, and the boss 54 is pressed against the cup-shaped member 51 integrated with the motor shaft 50 by the force of the leaf spring 74.

Therefore, in cooperation with the attraction force of the magnet 52, slips are prevented from occurring when the magnetic disk is rotated.

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

This opening 76 has a hole buried in the boss 54.
PG pin (index pin) 77 is faced,
The sensor 78 is also faced from above.

The sensor 78 is connected to a printed circuit board 79 fixed on the cassette guide 67, and is composed of a magnetoresistive element (MR element) or the like.

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

Although this magnetic field is extremely weak, the MR element sensor 78
detects this, the internal resistance value changes, and 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 and used as an index signal.

Please note that the MR element is sensitive to extremely weak magnetic fields, so when this example device is installed on a computer, etc.
Malfunctions may occur due to changes in magnetic flux generated around the CRT, transformer, and motor.

Therefore, in this embodiment, the cassette guide 67
is made of 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,
Since it uses an index detection mechanism using an MR element, the diameter is 10 to 15 mm as shown in Figure 5A.
It was possible to make the size almost within the size of the boss 54.

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, high-speed index detection device.

Note that one end of a pad lever 80 is rotatably attached to the back side of the cassette guide 67.
A pad 81 provided on the lower surface of the free end passes through the opening 82 of the cassette guide 67 and presses the magnetic disk 53 from above at a position corresponding to the magnetic head, thereby ensuring reliable contact between the magnetic disk and the magnetic head. can.

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 FIG.
It is configured as shown in ~C.

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

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

Further, a shutter 85 is provided at the opening 68a to prevent dust from entering through the opening 68a.
It is slidably fitted into the recess 86 including the recess 8a.

This shutter 85 can freely move to a position where it contacts one end 86a and the other end 86b of the recess 86, and opens and closes the opening 68a.

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

That is, the lever 6 of the cassette guide 67
One end of the opening/closing lever 87 is rotatably supported by a protrusion 89 on the cassette guide 67 side via a pin 88 at a position opposite to the side edge where the opening/closing lever 9 is provided.

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

On the free end side of the opening/closing lever 87, protrusions 87a and 87b, which serve as first and second stoppers, are provided protruding toward the cassette guide 67 side.

The first protrusion 87a has a slope 87c formed at its tip, with the cassette insertion opening side being lower.
The rear end side is an upright wall 87d.

On the other hand, there is a protrusion 91 on the inside of the cassette guide 67.
is provided protrudingly, and the opening/closing lever 87 is located at a position closer to the cassette insertion opening than this protrusion 91.
An opening 92 into which the projection 87a fits is formed.

Next, the operation of the opening/closing mechanism for the cassette shutter 85 constructed as described above will be explained.

17A to 17D explain the operation of opening the shutter. As shown in FIG. 17A, when the cassette 68 is inserted into the cassette guide 67 with the shutter 85 closed, the opening/closing lever 87 is The tip of the projection 87a of No. 1 contacts the edge of the shutter 85,
Eventually, 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.
is an opening 85a formed in the side surface of the shutter 85.
It is inserted into the shutter 85 from above.

When the cassette 68 is further pushed in, since the shutter 85 is blocked in that position by the protrusion 91, only the shutter 85 remains, and the shutter 85 is opened as shown in FIG.

On the other hand, the operation of closing the shutter 85 is shown in FIG.
This is done as shown in C.

FIG. 18A 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 edge of the opening 85a of the shutter 85 comes into contact with the upright wall 87d of the first protrusion 87a of the opening/closing lever 87, as shown in FIG. 18B. Therefore, the shutter 85 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. 18B.

At this time, the tip of the cassette 68 protrudes a predetermined distance from the cassette guide 67, so if you pick it up with your fingers and pull it out, the opening/closing lever 87 will not be able to resist the strong force and will be centered around the pin 88 as shown in FIG. 18C. The shutter is forcibly rotated counterclockwise in the figure, and the cassette 68 can be taken out with the shutter closed.

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, 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 pushed forward against the tensile force of the spring 48, and the slope 49a of the protrusion 49 is pushed under the pin 70 of the lever 69 on the cassette guide 67 side, and the pin 44 is pushed forward. 70 is positioned 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. 4A, the pin 71 is in a state riding on the protrusion 1b on the chassis 1 side, the lever 69 is in a state of being pulled toward the front side by the tensile force of the spring 72, and the lever 69 is in a state of being pulled toward the front side by the tensile force of the spring 73. The pin 71 is in a state of being pressed onto the projection 1b.

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

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

In this state, move the cassette 68 to the cassette guide 67.
When the cassette is inserted into the cassette, 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, and the lever 69 is pushed together with the cassette 68.

As a result, the spring 72 is moved until the extension pin 70 touches the right end of the elongated hole 69b, and as shown in FIG.
As shown in FIG. 2, the pin 71 comes off the protrusion 1b and comes into contact with the inner side edge of the protrusion 1b.

That is, the cassette guide 67
The boss 54 is fitted onto the motor shaft 50.

At the same time, the tip of the pad lever 80 is lowered and the pad 81 is moved toward the magnetic disk 53 against the magnetic head 14.
Press through.

In this state, the sensor 78 starts rotating the magnetic head, and the PG pin 77 performs index detection, and the rotation of the pulse motor 11 activates the head moving mechanism 2 to move the head.

When a +phase pulse is applied to the pulse motor 11, its output shaft 24a is rotated clockwise in FIG.
- Applying a phase pulse causes it to rotate counterclockwise.

Here, via the pinion gear 25, the gear 29,
When 30 is rotated clockwise in Fig. 9, the screw shaft 2
7 is also rotated in the same direction, and the gears 29 and 30 move in the direction of the shutter plate 37.

When the gears 29, 30 are rotated counterclockwise, the gears 29, 30 are separated from the shutter plate 37.

Now, when the gears 29 and 30 rotate clockwise in FIG. 9 and move toward the shutter plate 37, the pin 34 protruding from the boss 28 comes into contact with the lower edge of the shutter plate 37 as shown in FIG. start.

Then, the shutter plate 37 is rotated counterclockwise in FIG. 11 about the shaft 36.

The opening 41 of the shutter plate 37 is normally
sensor 4 because it does not match the opening 42 of sensor 4.
The light from the light emitting element 3 hits the shutter plate 37 and is reflected, and is detected by the light receiving element at the sensor 43.
is in the on state.

However, the gears 29 and 30 move toward the shutter plate 37 from the state shown in FIG. 10A to the state shown in FIG. When rotated counterclockwise, the opening 41, as shown in FIG.
42 match, and the light from the light emitting element of the sensor 43 passes through and does not return to the light receiving element. Therefore, sensor 43 is turned off.

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

If the distance L from the center of the magnetic disk to the outermost circumference of the track is 20 mm, the magnetic head will be 20 mm from the center.
This meant that it was located at the outermost periphery of the distant track.

However, due to variations in component accuracy, even if the opening 41 of the shutter plate 37 and the opening 42 of the support plate 24 match, the magnetic head is not necessarily positioned at L=20 mm.

Therefore, adjust the screw 35 that the tip of the screw shaft 27 touches so that L=20 mm.

The adjustment method is to first set the openings 41 and 42 to match as shown in FIG.
3 is turned off, and the screw 35 is rotated using a microscope or the like in FIG. 8 so that the distance from the center of the motor shaft 50 to the magnetic head 14 is 20 mm.

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

According to the inventor's experiments, the pitch of the screw 35 is
By setting it to 0.3mm, ±2μm for L = 20mm
It was possible to fully adjust the degree.

Note that since the thread pitch of the screw shaft 27 is set to 0.5 mm, the pin 3
When the screw shaft 27 rotates once in the counterclockwise direction in FIG. 9 from the state where the screw shaft 4 is in contact with the lower edge of the shutter plate 37,
The pin 34 is connected to the shutter plate 3 as shown in FIG. 10C.
Stay away from 7.

That is, from the state shown in FIG. 10A to the state shown in FIG.
4 hits the shutter plate 37, otherwise the sensor 43 will not be turned off.

By the way, while rotating the shutter plate 37 from the state shown in FIG. 11 to the state shown in FIG.
is rotated by β=9°, and the sensor 43 is turned off.

When the screw shaft 27 rotates by 9 degrees, the pin 34 moves in an arc shape by about 0.4 mm.

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

Therefore, in this embodiment, the distance from the center of the shaft 36 to the position where the pin 34 contacts is set to 1/3 of the distance from the center of the pin 36 to the openings 41 and 42.
The 0.4 mm displacement of the pin 34 is expanded to 1.2 mm 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 an additional 9° from the state shown in Fig. 12.
The screw shaft 27 is shown in a rotated state.

In this state, α = 18°, 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 44 via the eject button 47, and as described above, the protrusion 49 of the eject lever will eject the cassette guide 67 via the pin 70. is lifted up. This state is the state shown in FIG. 4A described above.

At this time, the force of the spring 72 causes the lever 6 to
9 returns, the cassette 68 is pulled out by the bent portion 69d of the lever 69.

Since the cassette 68 protrudes from the cassette guide 67, although the distance it is pulled out is small, 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-mentioned example, the head moving mechanism 2
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 employ such a modification, two head arms 12 and 12a may be integrally formed, and the magnetic head 14 may be attached to each.

[Effects] As is clear from the above description, according to the present invention, a screw shaft that moves forward and backward in the moving direction of the head moving mechanism is juxtaposed to the pulse motor, and means for transmitting the rotation of the pulse motor to the screw shaft. is provided to be relatively movable between the pulse motor and the screw shaft, the tip of the screw shaft is brought into contact with the head moving mechanism, and the head moving mechanism is brought into contact with the tip of the screw shaft. Because the screw shaft and head movement mechanism are pressed together by a spring, the screw shaft and head movement mechanism can be engaged in a very small area. The frictional force is much smaller than when it is transmitted through the threaded surfaces (male and female threads) of the moving mechanism.

Therefore, since the force for moving the head, that is, the driving force converted into rotation of the screw, can be reduced, a pulse motor that is small and consumes little power can be used.

In addition, the screw shaft that moves forward and backward in the moving direction of the head moving mechanism is arranged in parallel to the pulse motor, so in addition to miniaturization achieved by reducing the driving force of the motor, It becomes possible to use space effectively and achieve further downsizing.

[Brief explanation of the drawing]

The figure explains one embodiment of the present invention.
The figure is an overall perspective view, Figure 2 is an exploded perspective view, Figures 3A and B are partial longitudinal side views of the cassette guide and eject lever when the cassette is attached, and Figure 4
Figures A and B are partially longitudinal side views of the cassette guide and eject lever when ejecting the cassette;
Figures A and B are a plan view of the magnetic disk holding mechanism and a vertical side view of the magnetic disk drive unit, Figure 6 is a vertical side view of the main parts of the magnetic disk drive mechanism, Figure 7 is a vertical side view of the head moving mechanism, FIG. 8 is a plan view of the head moving mechanism, FIG. 9 is an exploded perspective view of the outermost track detection mechanism, FIGS. 10A to C are plan views explaining the operation of the outermost track detection mechanism, and FIGS.
Figure 13 is a front view illustrating the operation of the shutter plate;
FIG. 14 is a plan view illustrating a modification of the head moving mechanism, FIGS. 15 A to C are plan views, front views, and vertical side views of the magnetic disk cassette, and FIGS. 16 A and B.
17A to 17D are plan views illustrating the shutter opening operation, and FIGS. 18A to 18C are plan views illustrating the shutter closing operation. 1... Chassis, 2... Head movement 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...pin, 74...leaf spring,
78...Sensor.

Claims (1)

[Scope of Claims] 1. In a magnetic disk device in which a head moving mechanism on which a magnetic head is mounted is driven by a pulse motor, a screw shaft that moves forward and backward in the moving direction of the head moving mechanism is arranged in parallel with the pulse motor, and the pulse A means for transmitting the rotation of the motor to the screw shaft is provided to be movable relative to the pulse motor and the screw shaft, the tip of the screw shaft is brought into contact with the head moving mechanism, and the head A magnetic disk device characterized in that a moving mechanism is provided by being pressed by a spring in a direction in contact with the tip of the screw shaft.