JPS6180571A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To detect surely a minute position change of a head by providing a sensor whose output is turned of when an opening formed with a support plate fixed with a shutter plate and a screw cylinder screwed to a screw shaft is coincident with the turning of the shutter plate. CONSTITUTION:When gears 29, 30 are rotated clockwise with a pulse fed to a pulse motor 11, a shaft 27 is rotated in the same direction, and when the gears 29, 30 are moved in the direction of the shutter plate 37, a pin 34 provided to a boss 28 starts contact with the lower side ridge of the shutter plate 37, which is turned counterclockwise. Since the opening 41 of the shutter plate 37 is not aligned with the opening 42 of the support plate 24 normally, the sensor 43 is turned on. When the pin 34 contacts the lower side of the shutter plate 37 and the openings 41, 42 are aligned, the light from a light emitting element of the sensor 43 is transmitted and not returned to the photodetector, the sensor 43 is turned off. It is recognized by it that the magnetic head 14 reaches the outermost circumference of the track.

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 drive, in order to detect when the magnetic head has reached the outermost position of the track, a detection piece is provided in a part of the head movement mechanism that moves along the two guide shafts, and an optical sensor, etc. By detecting this, it is detected that the magnetic head has reached the outermost position of the track.

However, with such a structure, as devices become smaller, the moving distance of the magnetic head for one track has become extremely small, approximately 125 gm, making it difficult to detect minute positions.

[Objective] The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and provides a magnetic disk device configured to be able to reliably detect minute movement distances of a magnetic head. The purpose is to

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 according to 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 mechanisms 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 fixed to each side of the guide 5 and to opposing positions on the sides of the U-shaped slider 6, for a total of four guide bars 7.
A plurality of steel poles 8 are arranged in contact with each other.

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.

In addition, if there is play between the guide bar 7 and the steel pole 8, the slider 6 cannot move linearly with high precision. , removing 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 is bent and extends along one side of the slider 6, is guided along the surface of the chassis l, and has its tip end. A magnetic head 14 is fixed to the upper surface via a head stand 13.

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

Further, a torsion coil spring 17 is attached to the upper surface of the head arm 12 in the vicinity of the head stand 13, one end of which is in contact with the pin 18 on the helad arm 12, the other end is in contact with the side surface of the head stand 13, and the head The stand 13 is pressed toward the tip of the head arm 12.

A bent portion Lea is formed at the tip of the head arm 12, and a screw 19 is screwed into the bent portion Lea. 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 the center of the magnetic head and a straight line passing through the motor shaft, which will be described later, is reduced to 0. can do.

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.
2.23 is 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 post 28.
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 steel 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 moving the head.

On the other hand, the support plate? A shaft 36 is protruded from the outer surface of the shutter 4 in the vicinity of the screw shaft 27, and a shutter plate 37 is rotatably supported at one end of the shaft 36 via a post 37a.

A spring piece 38 is provided above the end of the shutter plate 37 on the post 37a side, and the tip of the spring piece 38 is connected to the outer surface of the support plate 24 and a pin 3 that is protruded above the screw shaft 27.
It touches the bottom of 9.

The shutter plate 37 is given the habit of rotating clockwise in FIG. 9.

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

Also, the shutter plate 37 and the support plate? Openings 41, 42 are formed at positions that can coincide with 4. Support plate 24
A photosensor 43 consisting of a light emitting element and a light receiving element is provided on the back side of the opening 42 .

This shutter plate 37 constitutes a pulse generating means (TR "00" 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 provided in the chassis 1.
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 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 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 cassette mounting mechanisms 4, 4, which will be described later.

The chassis 1 also includes head moving mechanisms 2.2 and 2.
A motor shaft 50 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 50, 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 50 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 50 is fitted into the post 54 as will be described later, 3.
The magnetic flux of the magnet 52 is guided through the vicinity of the cup-shaped member 51, and the washer 55 made of a magnetic material can be attracted by the 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 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 l in a state surrounding the motor shaft 50, and a ring-shaped coil 65 is fixed to the printed circuit board 64. They are facing each other.

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, and the other motor shaft can also be rotated.

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.
are rotatably supported on bent portions 1a and 1a provided in the vicinity of the head moving mechanism 2 of the chassis 1, 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. A protrusion 67a cut and raised from the cassette guide 67 is fitted into the 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 1b protruding from the chassis 1 at a position closer to the cassette insertion opening.

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 l 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 is provided at the tip of the leaf spring 74 to fit into the elongated hole 67b.

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 67'b.

This opening 76 has a PG pin (
Index pin) 77 is shown.

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 has a magnetoresistive effect element (MR).
It consists of elements such as

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

Although this magnetic field is extremely weak, the sensor 78 of the MR element 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.

Incidentally, 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 magnetic flux generated from the vicinity of the CRT, the vicinity of the transformer, and the vicinity of 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 FIG. 2, the size could be made almost within the size of the post 54, which has a diameter of 10 to 15 mm.

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, thereby releasing the magnetic field. The disk and the magnetic head 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 disc 7-2 Toro 8 has a flat case made up of two upper and lower cassette halves 84 made of hard synthetic resin, etc., and a magnetic disc 53 is rotatably inserted into the case through a post 54. It is accommodated.

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 lower, and an upright wall 87d at its rear end.

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, the shutter 85 of the cassette configured as described above is
The operation of the opening/closing mechanism will be explained.

17(A) to 17(D) explain the operation of opening the shutter. As shown in FIG. 17(A), when the cassette 68 is inserted into the cassette guide 67 with the shank 85 closed, , the tip of the first protrusion 87a of the shutter 87 comes into contact with the edge of the shutter 85, and eventually the tip of the first protrusion 87a rides on the side surface of the shutter 85 as shown in FIG. 8(B).

If you push the cassette 68 further in this state y〃(,
), the edge of the shutter 85 touches the protrusion 91,
At the same time, the first protrusion 87a of the opening/closing lever 87
It fits into the shutter 85 through an opening 85a formed on the side surface of the shutter 85.

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, and as shown in FIG.
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. 18(B).
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(B).

At this time, the tip of the cassette 68 is connected to the cassette guide 67.
Since it protrudes a predetermined distance from the lever, if you pick it up with your fingers and pull it out, the opening/closing lever 87 will not be able to withstand the strong force and will move as shown in Figure 18 (
As shown in C), the cassette 68 is forcibly rotated counterclockwise in the figure around the pin 88, 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 and the rotor 58.
The rotating remotor shaft 50 rotates.

In this state, there are no cassettes (
・68 can be installed. Before the cassette 68 is installed, the eject lever 44 is
8, the protrusion 49 is pushed forward by pushing against the tensile force of the protrusion 49, and the slope 49a of the protrusion 49 is pushed under the pin 70 of the lever 69 on the cassette guide 67 side, so that the pin 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. 4(A), the pin 71 is in a state riding on the protrusion lb on the shear 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, the front side of the cassette guide 67 is lifted up, and 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 elongated pin 70 of the spring 7z is inserted into 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 descends as the cassette moves down, and the post 54 is fitted onto the motor shaft 50.

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

In this state, the rotation of the magnetic head is started, index detection is performed by the sensor "78" and the PG pin 77, and the head moving mechanism 2 is operated by the rotation of the pulse motor 11 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 through 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 shutter plate 37.

Now, when the gears 29 and 30 rotate clockwise in FIG. 9 and move toward the shutter plate 37, the pin 3 protruding from the post 28
4 begins to touch the lower edge of the shutter plate 37 as shown in FIG.

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

Since the opening 41 of the shutter plate 37 usually 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 shutter 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 toward the shutter plate 37 from the state shown in FIG. 10 (A) to the state shown in FIG. When the plate 37 is rotated counterclockwise in FIG.
As shown in FIG. 2, the 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, so the sensor 43 is turned off.

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

Distance gIL from the center of the magnetic disk to the outermost circumference of the track
If the distance is 20 mm, the magnetic head is located at the outermost periphery of the track, 2θ distance from the center.

However, due to variations in component precision, even if the opening 41 of the shutter plate 37 and the opening 42 of the support plate 24 match, L=
The magnetic head is not necessarily positioned at 2hm.

Then, turn the screw 35 that the tip of the screw shaft 27 touches, and
Adjust JJ so that = 20mm.

The adjustment method is to first open the opening 41.4 as shown in Figure 12.
2 are set to 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 2hm using a microscope or the like as shown in FIG. .

Then, when L=20a+m, the screws 35 are locked using adhesive or the like.

According to the inventor's experiments, the pitch of the screw 35 was set to 0.3 m.
By making it into the intestine, ± 2J for L = 20mm
Adjustment of about Ll was sufficiently possible.

Note that since the thread pitch of the screw shaft 27 is set to 0.5 sm, the pin 34 is in contact with the lower edge of the shutter plate 37 as shown in FIG. When the screw shaft 27 rotates once in the clockwise direction, the pin 34 separates from the shutter plate 37 as shown in FIG. 1θ (C).

That is, between the state shown in FIG. 10 (A) and the state shown in FIG. 10 (B), the pin 34 hits the shutter plate 37 and turns off the sensor 43 only when the pin 34 hits the shutter plate 37. Yes, otherwise sensor 43
It never turns off.

Incidentally, while rotating the shutter plate 37 from the state shown in FIG. 11 to the state shown in FIG. 12, the screw 27 rotates by β=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.
Moves 4mm.

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

Therefore, in this embodiment, the pin 34 is
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
Using the rotation of the shutter 37, the displacement of m is 1.2 mm.
openings 41 and 42 through which the light from the sensor 43 passes.
The aim is to increase efficiency by increasing

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 by utilizing the lever ratio of the shaft plate 37 to improve the efficiency of the senna.

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°, the sensor 43 is turned on, and it is possible to detect that the magnetic head 14 has protruded beyond L = 20+wm, and it is possible to obtain a signal 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 7o. This state is the state shown in FIG. 4(A) described above.

At this time, the force of the spring 72 causes the cassette 69 to return, so the bent portion 69d of the lever 69
is brought out.

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 the above example, two head moving mechanisms 2 are provided individually, but the present invention is not limited to this, and as shown in FIG. 14, one head moving mechanism 2 is provided. Just one piece is fine.

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

[Effect] As is clear from the above description, according to the present invention, the screw shaft that moves forward and backward by being transmitted with the rotational force of the pulse motor engages with the pin provided on the boss integrated with the screw shaft. An opening formed in a support plate to which a rotating shutter plate and a screw cylinder into which the shutter plate and screw shaft are screwed are fixed.
The sensor is configured to turn off when the rotation of the shutter plate coincides with the rotation of the shutter plate, so the slight rotation of the screw shaft is magnified by the lever ratio of the shutter plate, ensuring minute positional changes in the head. can be detected.

[BRIEF DESCRIPTION OF THE DRAWINGS] The figures are for explaining one embodiment of the present invention. The first figure is an overall perspective view, the second figure is an exploded perspective view, and the third figure (A), (
B) is a partially longitudinal side view of the cassette guide and eject lever in the cassette installed state, FIG. 4(A), CB
) is a partially vertical side view of the cassette guide and eject lever during cassette ejection, Figures 5(A) and (B) are a plan view of the magnetic disk holding mechanism and a vertical side view of the magnetic disk drive unit, and Figure 6 is a vertical side view of the magnetic disk drive unit. FIG. 7 is a longitudinal side view of the main parts of the magnetic disk drive mechanism; FIG. 7 is a longitudinal side view of the head moving mechanism;
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 10C are plan views explaining the operation of the outermost track detection mechanism, and FIG. 1
Figures 1 to 13 are front views illustrating the operation of the shutter plate;
FIG. 14 is a plan view illustrating a modification of the head moving mechanism;
15(A) to 15(C) are a plan view, a front view, and a longitudinal side view of the magnetic disk cassette, and FIGS. 16(A) and 16(B) are an exploded perspective view and a plan view illustrating the shutter opening/closing mechanism. 17(A) to (D) are plan views illustrating the shutter opening operation, and FIGS. 18(A) to 18(C) are plan views illustrating the shutter closing operation. 1... Chassis 2... Head moving mechanism 3.
...Motor 4...Cassette mounting mechanism 6...
・Slider 11...Pulse motor 14...
Magnetic 5-piece 19, 21.35... Screw 27...
Screw shaft 43...Senna 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.
...Plate spring 78...Sensor Fig. 10 (A) Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 (A) Fig. 16 (B) Fig. 18 (A)

Claims (1)

[Claims] In a magnetic disk drive in which a head movement mechanism is operated by a pulse motor, a screw shaft that moves forward and backward by being transmitted with the rotational force of the pulse motor, and a pin provided on a boss integrated with this screw shaft are screwed together. a shutter plate having one end rotatably supported on a support plate provided with a threaded cylinder, the lower edge of which is rotatable in a direction in which it engages with the pin; A magnetic disk drive characterized in that a sensor is provided that turns off when openings formed in a plate are aligned.