JPH0743920B2 - Magnetic disk unit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device having an improved chassis structure of the magnetic disk device.

[Prior Art] Conventionally, a chassis of a magnetic disk device is made of aluminum.

When such a chassis is used, the motor that rotationally drives the magnetic disk is provided separately from the chassis.

However, if such a structure is adopted, there is a drawback that the device is increased in size by the amount of the motor provided and the cost is increased.

[Objective] The present invention has been made to eliminate the above-mentioned conventional defects, and an object thereof is to provide a small-sized and inexpensive magnetic disk device.

[Examples] Hereinafter, details of the present invention will be described based on Examples shown in the drawings.

The magnetic disk device according to the present invention is assembled based on the chassis 1. The chassis 1 is configured as a U-shaped frame body having left and right side plates 2 and 2, and a guide groove 3 is formed at a position where the side plates 2 and 2 face each other from an upper edge toward a lower side.
3 is formed. Rollers protruding from the cassette guide side, which will be described later, are fitted into the guide grooves 3, 3.

A guide hole 4 is formed in a horizontal state at a position where the side plates 2 and 2 face each other between the guide grooves 3 and 3.
A guide groove 5 is also formed in a horizontal state on the front side edge. A guide roller of a slide frame, which will be described later, is fitted in the guide hole 4 and the guide groove 5.

On the other hand, on the bottom plate 6 of the chassis 1 with a predetermined arrangement,
A book positioning pin 7 is provided in a protruding manner.

These pins 7 position the cassette, which will be described later, in the vertical direction.

A pulse motor 8 serving as a drive source for moving the magnetic head is fixed to one end side of the bottom plate 6 of the chassis via stods 8a, 8a, and a protrusion 9 that cuts and raises the bottom plate 6 is provided in the vicinity thereof.
Is projected. A through hole 10 is formed in the projecting piece 9, and a through hole is formed in one of the side plates 2 while facing the through hole 10.
11 are formed. A guide shaft 12 that guides a head mount, which will be described later, is horizontally installed using these through holes 10 and 11.

Further, on the front side of the chassis 1, another guide bar 13 is provided horizontally between the side plates 2 and 2 in parallel with the guide shaft 12.

On the other hand, a drive gear 14 is fixed to the output shaft of the lower side of the pulse motor 8, and the drive gear 14 meshes with a gear 15 rotatably supported on the bottom plate 6.

A through hole 16 is formed in substantially the center of the bottom plate 6, and a boss for bearing the rotation drive mechanism of the magnetic disk is formed in this through hole 16.
17 is installed.

As shown in FIG. 3, the boss 17 has a flange 17a on the outer periphery of its central portion, and this flange 17 is superposed on the upper surface of the bottom plate 6,
The lower portion of the boss 17 is fitted into the through hole 16 and fixed by the screw 18 via the flange 17a.

A rotary shaft 20 is rotatably supported in the boss 17 via a pair of upper and lower bearings 19, 19. Upper and lower bearings 19
A collar 21 is arranged between them. The outer ring of each bearing 19, 19 is press-fitted into the boss 17.

A coupler 22 is fixed to the upper end of the rotary shaft 20. Coupler
Reference numeral 22 is fitted to the center hub of the magnetic disk cassette, and a positioning pin 23 is fitted to the flange 22a of the magnetic disk cassette in a vertically movable manner.

The lower end of the pin 23 is below the flange 22a, and the leaf spring 24
It is fixed to the free end side of the and is given the habit of moving in the direction that it always projects.

A spring 25 is mounted between the lower surface of the coupler 22 and the inner ring of the upper bearing 19, and by pressing the inner ring downward, a relative positional deviation is generated between the inner ring and the outer ring. The uniform contact between the ball and the ball is generated, the backlash of the inner and outer rings is eliminated, and the runout of the rotating shaft 20 is prevented.

A gear 27 is fitted and fixed to the boss 17 via the boss 28 with the cam 26 on the upper side. The gear 27 meshes with the gear 15 to rotate the pulse motor 8 via the cam 27 on the head side. Communicate to. A washer 29 for tightening is fitted on the outside of the boss 28 to prevent the cam 26 and the like from coming off.

On the other hand, the reference numeral 30 indicates a head base, which is formed in an elongated plate shape. One end of the head base 30 is a linear bearing 31
It is slidably fitted to the guide shaft 12 via.

The other end of the head base 30 is slidably guided by another guide shaft 13.

That is, as shown in FIG. 5 (C), a shaft 33 for rotatably bearing a circular roller 32 is provided so as to project downward on the free end side of the head base 30. A spring 34 is mounted between the shaft 33 and the roller 32 to give the roller 32 a tendency to move upward.

Further, the shaft 33 is fixed to the head base 30 side by a screw 35, but a leaf spring is provided on the upper side of the head base 30 by the screw 35.
One end of 36 is fixed.

A roller 37 is rotatably fitted in the opening 30a formed in the head base 30 whose upper side is covered by the leaf spring 36 so as to be orthogonal to the guide shaft 13.

Therefore, the guide shaft 13 is elastically sandwiched between the slope of the circular roller 32 and the roller 30, and is slidably attached to the guide shaft 13.

In this way, the shafts 12 and 13 that guide the movement of the head base 30 have a very small friction because they have a bearing member that uses rotational friction by a linear bearing and rollers, and are much smoother than bearings that use sliding friction. You can move the head stand.

Therefore, the pulse motor 8 can be a small-sized, low-power, inexpensive motor.

However, as shown in FIG. 5B, the guide shaft 12 is guided by the bearing member 38 utilizing sliding friction.
In addition, if the bearing member 38 is made of a material that is expensive but has extremely excellent wear resistance, such as ruby, an inexpensive material can also be used as the pulse motor.

A spring 39 is stretched between the head base 30 and the projecting piece 9 to give the head base 30 a habit of moving toward the rotary shaft 20.

This head base 30 is arranged above the cam 26,
On the back surface of the head 30, one end of a lever 40 is rotatably supported by a screw 41.

A spring 42 is stretched between the other end of the lever 40 and the head base 30 to give the lever 41 a turning tendency in the counterclockwise direction in FIG.

A roller 44 is rotatably supported on the lower surface of the lever 41 via a pin 43, and the roller 44 is in contact with the cam surface of the cam 26.

By the way, as shown in FIG. 6, the cam 26 has a spiral and a large number of saw-toothed cam surfaces as a whole, and the sawtoothed cam portion is used, for example, when the number of tracks of the magnetic disk is 40. Has 40 corresponding cam parts.

The radius represented by the symbol RO in FIG. 6 is the maximum radius.
Each cam portion is set so that the radius represented by R39 becomes the minimum radius, and the magnetic head can be moved from the outermost track to the innermost track of the magnetic disk.

It is the pulse motor 8 that rotates this cam, and the rotation is transmitted through the gears 14, 15, and 27.

Actually, when one driving pulse is input to the pulse motor 8, the pulse motor 8 is set to rotate 18 °, and when a positive phase pulse is added, the motor rotates to the right,
When a pulse of opposite phase is added, it rotates counterclockwise.

The gear ratios of the gears 14, 15, 27 are set so that the gear 27 rotates 6 ° when the pulse motor 8 rotates 18 °.
Within this 6 ° range, 40 cams with radii RO to R39 are formed.

Therefore, the magnetic head moves by one track each time the cam rotates 6 °, and the specific moving amount is 0.12 mm.
The total width of all 40 tracks is about 5 mm.

On the other hand, a bent portion protruding in the middle of the head base 30 in the longitudinal direction.
An adjusting screw 45 is screwed into the 30a as shown in FIG.

The tip of the adjusting screw 45 is in contact with the bent portion 40a formed on the side edge of the lever 40 on the free end side as shown in FIGS. 24 (A, B), so that the position of the lever 41 can be adjusted. You can

In addition, a longitudinal opening is formed in the middle of the head base 30 in the longitudinal direction.
30b is formed therein, and a magnetic head 47 is arranged in this via a support member 46.

A projecting piece 4 projecting from one end of the support member 46 and one end of the opening 30b.
An arc-shaped leaf spring 49 is elastically mounted between itself and 8, and the tip end of the adjusting screw 51 screwed into the projecting piece 50 projectingly provided on the other end side of the opening 30b is the supporting member 46. It is in contact with the side edge opposite to the spring 49.

Therefore, by turning the adjusting screw 51, the position of the support member 46 can be adjusted, and the position of the magnetic head 47 can be adjusted.

The adjusting screw 51 can correctly adjust the center of the magnetic head with respect to the center of the magnetic disk.

After properly adjusting the position with the adjusting screw 51, the support member 46 may be completely fixed to the head base 30 with the screw 52.

By the way, brackets 53, 53 are provided so as to project from the end of the head base 30 on the guide shaft 12 side, and one end of the pad arm 54 is rotatably supported via a pin 55 by using these brackets 53. ing.

A torsion coil spring 56 is wound around the pin 55 to give the pad arm 54 a habit of turning clockwise in FIG.

The tip of the pad arm 54 extends above the magnetic head 47, and an adjusting screw 57 is screwed into the tip of the pad arm 54 in correspondence with the magnetic head 47, and a pad 58 for pressing the magnetic disk is provided at the lower end thereof. Has been.

Therefore, if the screw 57 is rotated, the pad 58 and the magnetic head 47 are rotated.
The parallelism between the and and the pad pressure can be adjusted.

On the other hand, a control plate 59 is integrally provided on the lower side of the gear 27, and a protrusion 59a is provided on a part of the control plate 59, and a cutout portion 59b is formed at the base of the protrusion 59a. .

A lever 61 is rotatably supported on the bottom plate 6 via a pin 60 on the side of the control plate 59. Protrusions 61a and 61b are formed at one end of the lever 61 even if they are separated by a predetermined distance, and these protrusions 61a and 61b are always in contact with the outer peripheral surface of the control plate 59.

The other end of the lever 61 is formed in an elongated shape, and faces the position where the upper side of the notch 6a formed at the front edge of the bottom plate 6 is closed. Then, facing the notch 6a, the sensor
62 are arranged. This sensor 62 is composed of, for example, a light emitting element and a light receiving element, and constantly receives the reflected light from the lower surface of one end of the lever 61 and monitors the existence of the lever 61.

By the way, the mounting position of the lever 61, the protrusion 59a, and the cam
There is the following relationship with the cam part with the maximum radius RO of 26.

That is, when the roller 44 reaches the cam portion having the maximum radius RO, the projection 59a is set in such a positional relationship that it can engage with the projection 61b of the lever 61.

Therefore, as shown in FIG. 6, when the roller 44 is in the cam portion having the radius RI, the protrusion 61b of the lever 61 is not in contact with the protrusion 59a, and one end of the lever 61 closes the upper portion of the sensor 62.

In this state, the protrusions 61a and 61b are in contact with the peripheral surface of the control plate 59, and the lever 61 does not rotate.

However, when the cam 26 is rotated by one extra step by the pulse motor 8, the roller 44 rides on the cam portion having the maximum radius RO, and the magnetic head 47, together with the head base 30, corresponds to the outermost track position. become.

At this time, as shown in FIG. 7, the protrusion 59a contacts the protrusion 61b of the lever 61, and the lever 61 is rotated counterclockwise in the drawing,
The protrusion 61b fits into the cutout portion 59b. Then, one end of the lever 61 is separated from the upper side of the sensor 62 at this time as shown in FIG. 7, the sensor 62 is turned off, and it is detected that the magnetic head has reached the outermost track.

Therefore, the outermost track is set to 0 track, and this position can be surely detected by the above-mentioned mechanism.
If the magnetic head is set so as to reach this position when the power is turned on, the head position at the start coincides with 0 track, and if the pulse to the pulse motor 8 is energized from this position, 5 pulses will be obtained. The track position can be freely selected so that the head moves to the 10th track in the case of the 10th pulse in the track.

The current position of the magnetic head with respect to these pulse inputs may be stored in the memory of the digital processing system.

By the way, the specifics between the control plate 59 and the lever 61 are as follows.

That is, as shown in FIG. 6, when the radius R of the control plate 59 is 15 mm and the rotation angle α in one step is α = 6 °, the movement distance δ of the peripheral edge of the control plate 59 is tan = 6 ° × 15 mm = 1.6 mm.

Also, if the distance B from the pin 60 to the tip of the lever 61 is 5 mm, the distance A from the pin 60 to the rear end is 13 mm, the moving distance of the rear end of the lever 61 is δ ₁ , and the rotation angle is α ', α' ＝ 15/5 × 6 ° ＝ 18 °, δ ₁ ≒ tan 18 ° × 13mm ≒ 4.2mm.

Therefore, when the peripheral edge of the control plate 59 rotates 1.6 mm, the lever 61 rotates about 18 ° because the lever ratio of the lever 61 is 3.

As a result, the outer end of the lever 61 is rotated by 4.2 mm, and the sensor 6
If the size of 2 is 3 mm, the sensor surface can be opened and closed sufficiently.

Of course, if the sensitivity of the sensor 62 itself is increased, the movement of the protrusion 59a itself of about 1.6 mm can be sufficiently detected, but the movement of the control plate can be detected easily and inexpensively by using the lever as described above. .

When such a lever is used, the rotation of the control plate 61, and hence the cam 26, can be detected outside without other components, so that it is possible to obtain a detection mechanism that is less subject to spatial restrictions.

By the way, a magnetic disk cassette is mounted on the coupler 22 provided at the upper end of the rotary shaft 20.

Most of the magnetic disk cassettes except the center hub are made of synthetic resin.

On the other hand, the drive mechanism side of the magnetic disk is mostly metallic, so that it is affected by thermal expansion.

The details are as follows.

That is, in FIG. 24 (A), the distance from the center of the rotary shaft 20 to the center of the magnetic head 47, that is, a certain track is l _1, and the distance between the peripheral edge of the center hub 63 and the center of the rotary shaft 20 is l ₂ Assuming that the distance from the periphery of the center hub 63 to the track is l ₃ , the part of l ₂ is metal and the part of l ₃ is synthetic resin. Specifically, if l ₁ = 20mm, l ₂ = 8mm, then l ₃ Is 12 mm.

On the other hand, if the distance from the center of the rotary shaft 20 to the track on the drive side is L ₁ , the content is the boss from the center of the rotary shaft 20.
The distance L ₂ to the peripheral edge of 28, the distance L ₃ from the boss 28 to the peripheral edge of the cam 26, and the distance L ₄ from the peripheral edge of the cam 26 to the track are the total, and each part is made of metal.

Therefore, if L ₂ = 8 mm and L ₄ = 1.5 mm, then L ₁ = 20 mm, so L ₃ = 20−8−1.5 = 10.5 mm.

Now, if the error between L ₁ and l ₁ is set to zero at a temperature of 25 ° C., and the temperature rises by 20 ° C. to 45 ° C., the following result is obtained.

That is, when the linear expansion coefficient of metal is 16 × 10 ^-6 mm / ° C and the linear expansion coefficient of synthetic resin film is 17 × 10 ^-5 mm / ° C, l ₁ and L ₁ are
When applied to l ₁ (1 + αt) −δ, the result is as follows.

l ₁ = l ₂ + l ₃ = (8 + 8 × 20 × 16 × 10 ^-6 ) + (12 + 12 × 20 × 17 × 10 ^-5 ) = 20.043mm L ₁ ＝ L ₁ ＋ L ₂ ＋ L ₃ ＝ (8 + 8 × 20 × 16) × 10 ^-6 ) (1.5 + 1.5 × 20 × 16 × 10 ^-6 ) + (10.5 + 10.5 × 20 × 16 × 10 ^-6 ) ＝ 20.006 mm That is, when the temperature rises by 20 ° C, L ₁ and l ₁ The difference is 20.043-2
0.006 = 37 μm goes wrong, and it becomes impossible to read the information on the magnetic disk accurately.

Therefore, in the present invention, if the material of the cam 26 is made of synthetic resin having substantially the same linear expansion coefficient as the magnetic disk 64, L ₁ is as follows.

L ₁ = (8 + 8 × 20 × 16 × 10 ^-6 ) + (1.5 + 1.5 × 20 × 16 × 10 ^-6 ) + (10.5 + 10.5 × 20 × 17 × 10 ^-5 ) = 20.038 mm By changing the material, the difference between L ₁ and l ₁ is 2
0.043−20.038 = 5 μm.

Therefore, the effect of thermal expansion can be sufficiently reduced.

In the present invention, the central positions of the magnetic head 47 and the roller 44 can be positioned by the adjusting screw 45.

Therefore, L ₁ can be accurately set to 20 mm while observing the position of the magnetic head 47 with a microscope or the like.

In FIG. 24 (B), the center position of the magnetic head and the roller 44 is δ.
It shows that it was shaken by the minute.

Further, since the cam 26 can rotate, there is a gap of δ ₂ between the boss 17 and the boss 28 as shown in FIG. 24 (A).

Therefore, when the cam 26 rotates, the gap δ ₁ between the bosses 17 and 28,
δ ₂ constantly changes, and the change directly affects L ₁ .

In order to eliminate this influence, in the present invention, the gap δ ₁ between the bosses 17 and 28 on the magnetic head side is constantly set to zero.
A spring 39 is stretched between the head base 30 and the projecting piece so that the head base 30 is constantly pulled toward the boss 28 side and is pressed against one side by a spring 42 so that the magnetic head position is set so as not to deviate from the track.

On the other hand, the rotary shaft 20 extends below the chassis 1,
A member that constitutes a motor is attached to the printed circuit board 65 side fixed to the lower side of the chassis 1.

That is, the coil 65a is soldered and fixed to the lower surface of the printed circuit board 65.

On the other hand, a boss 66 is fixed to the lower end of the rotary shaft 20, and a dish-shaped yoke 68 and a gear 69 are fixed to the boss 66 with screws 67.

A ring-shaped permanent magnet 70 is fixed to the upper surface of the yoke 68 so as to face the coil 65a.

Further, a non-reflecting plate 71 that generates one pulse when the yoke makes one rotation is fixed to the outer periphery of the yoke 68, and a sensor 72 for detecting this is fixed to the printed circuit board 65 side.

Since the yoke 68 is plated with nickel or the like, the sensor 72 including a light emitting element and a light receiving element can reliably detect the non-reflection plate 71, and this signal can be used as an index signal.

On the other hand, the reference numeral 73 is a sensor fixed to the printed circuit board 65 side, and includes a permanent magnet 74 and a yoke 75 continuous with the permanent magnet 74.
The yoke 75 faces the vicinity of the gear 69 as shown in FIG.

In addition, in FIG. 1 and FIG.
Electronic components such as I, those indicated by reference numeral 77 are printed circuit boards 65
Is a screw for fixing to the chassis 1.

By the way, the gear 69 is formed of a ferrous material and has a large diameter, and when the tooth tips approach the yoke 75, a magnetic flux change occurs and a current flows through the coil on the sensor 73 side, and this is taken out as a signal. You can

The coil 65a and the permanent magnet 70 side described above constitute a motor for rotating the magnetic disk.

By the way, this motor is set to rotate once in 200 ms.

Then, the 200 ms is finely divided so that accurate rotation control can be performed so that it can rotate at a constant speed without shaking during this one rotation of 200 ms.

That is, the diameter of the gear 69 is 50 mm and the module is 0.25
Since the number of teeth is 200, the rotation change by the sensor 73 is monitored at intervals of 200 ms / 200 = 1 ms.

The printed circuit board 65 is a thin insulating substrate and is fixed to the iron chassis 1. The magnetic flux generated by energizing the coil 65a provided integrally is formed between the chassis 1 and the yoke 68. Permanent magnet 7 through the magnetic circuit
Therefore, the yoke 68 and the gear 69 are rotated.

By fixing the printed circuit board 65 to the iron chassis 1 as described above, the space between the permanent magnet and the chassis can be narrowed, and the efficiency of the magnetic circuit is improved.

Furthermore, if the chassis 1 is made of an iron-based printed board, the thickness of the motor portion can be reduced by the thickness of the printed circuit board 65 that constitutes the motor, and the number of parts can be reduced.

By the way, since the permanent magnet 70 is given a force to be attracted to the chassis 1, the inner ring of the lower bearing 19 is boss 66.
Since it is pressed upward by this, the play of the bearing 19 can be absorbed and the deflection of the rotary shaft 20 can be prevented together with the bearing 19 on the upper side.

On the other hand, since the inner and outer diameters of the boss 17 fixed to the chassis 1 side are machined at the same time on the basis of the fixed portion to the chassis 1, the inner and outer diameters can be machined to about 1 to 2 μm.

By virtue of this processing accuracy and the play of the bearing 19, the swing of the rotary shaft 20 including the boss 17 can be maintained within 5 μm.

The description of the drive mechanism section is completed above, and then the cassette mounting mechanism section is described.

The cassette mounting mechanism employs the structure shown in FIGS.

That is, in the figure, the reference numeral 78 is a slide frame which is formed as a frame body whose lower side and front and rear are opened. Rollers 79 are rotatably supported on both side surfaces of the slide frame 78. It is slidably and rotatably fitted in a horizontal long hole 4 formed in both side plates 2, 2 of the chassis 1.

Openings 78a are formed at the corners of the upper and left ends of the slide frame 78.
Is formed, and a projecting piece 78b integrally projects from the upper surface of the slide frame 78, passing above the opening 78a. This protrusion 78b and the protrusion 2 provided on the side wall of the chassis 1
A spring 80 is stretched between a and.

Therefore, the slide frame 78 is given a force in a direction projecting from the chassis 1 to the front side.

A roller 81 is rotatably supported by a projecting piece projecting from the lower ends of both side plates of the slide frame 78, and the roller 81 can slidably move on the chassis 1 via the roller 81.

A push button 82 is fixed to a protrusion 78c protruding from one end of the slide frame 78.

Further, slanted long holes 83 are formed in two parallel positions on the left and right side plates of the slide frame 78.

Slide plates 84 are slidably disposed on the left and right inner side surfaces of the slide frame 78.

The slide plate 84 is formed in a rectangular shape, and its lower end is in contact with the small-diameter shaft portion 81a of the roller 81 which is in contact with the bottom plate 6 of the chassis 1.

A protrusion 84a is provided on the upper end of the slide plate 84, and the protrusion 84 is fitted into the opening 78a of the slide frame 78 and serves as a guide.

Further, a bent portion 84b that is bent inward is formed at the tip of the slide plate 84.

Further, the slide plate 84 has a long hole 83 in the slide frame 78.
A substantially L-shaped opening 85 is formed at a position substantially corresponding to.

A projecting piece 84c is provided on the inner side of the tip of the slide plate 84, and a spring 8b is stretched between the projecting piece 84c and the slide frame 78.

By the way, below the slide frame 78, the cassette guide 87
Are arranged.

The cassette guide 87 is formed as a flat frame body,
Rails 87a are formed on the left and right of the rail to guide the cassette.

Further, projecting pieces 88 are projectingly provided on the left and right sides of the cassette guide 87, and each projecting piece 88 is projectingly provided with a pin 89, and a roller 90 is rotatably supported by the pin 89. .

Each roller 90 is rotatably fitted in the slide plate 84, the opening 85 of the slide frame 78, and the elongated hole 83.

Also, at the center of the top surface of the cassette guide 87, an opening 87
b is formed and a frame 91 is integrally provided so as to straddle the opening 87b, and a hub retainer 92 is attached to the frame 91.

Further, an opening 87c into which the magnetic head is fitted is formed on the side of the opening 87b.

As described above, the cassette mounting mechanism is composed of the three members of the slide frame 78, slide plate 84, and cassette guide 87 described above.

Next, the operation of this cassette mounting mechanism will be described.

Before the magnetic disk cassette 93 is mounted, the slide frame 78 is moved by the pulling force of the spring 80 as shown in FIG.
13 Moved to the right in the figure.

In this state, the roller 90 is located in the guide groove 3 and located at the upper end of the elongated hole 83 as shown in FIG.
Further, it is located on the step portion 85a of the L-shaped opening portion 85.

That is, the roller 90 is in a state of being regulated by the guide groove 3, the long hole 83, and the opening 85.

Further, the slide plate 84 is also pulled to the right side in FIG. 13 by the spring 86, and the cassette guide 87 has the step portion 85.
It is in a system to receive cassettes in the upper position regulated by a.

In this state, set the cassette 93 to the rail part of the cassette guide 87.
When the cassette 93 is fitted into the rail 87a, the cassette 93 is guided by the rail portion 87a and is guided to the back.

Eventually, the tip of the cassette 93 comes into contact with the bent portion 84b at the tip of the slide plate 84, and the slide plate 84 is moved forward against the tensile force of the spring 86.

Then, as the slide plate 84 moves, the opening 85 also moves. Therefore, as shown in FIGS. 12 (A) and 12 (C), the opening 85 is located in the guide groove 3 and on the step 85a of the opening 85. Aura 90
Will fall toward the vertical portion of the opening 85, and will be guided below the guide groove 3 and the vertical portion of the opening 85, as shown in FIGS. 12 (B) and 12 (D).

That is, the cassette 93 moves downward together with the cassette guide 87.

By the way, by the insertion operation of the cassette, the roller 90 is located at the upper end of the elongated hole 83 as shown in FIG. 12 (E), and then is moved to the lower portion of the elongated hole 83 shown in FIG. Moving.

During this movement, the roller 90 pushes the right side edge of the elongated hole 83, so that the slide frame 78 is moved to the right by a predetermined distance as shown in FIG.

When the cassette guide 87 descends together with the cassette 93 in this way, the protrusion of the positioning pin 7 having the protrusion 7a
7a is fitted in the positioning hole 93a of the cassette 93, and the projection 7a
The upper end of the pin 7 which does not have is contacted with the lower surface of the cassette to support and position the cassette. This state is shown in FIG.

At this time, as shown in FIG. 11, the coupler 22 is a magnetic disk.
The hub 23 is fitted in the central portion of the hub 94, and the pin 23 is fitted in the positioning hole 96 formed in the hub 95. Further, the upper surface of the hub 95 is pressed by the hub presser 92.

This mounting operation is performed while the rotary shaft 20 is rotating.

When the cassette 93 is set in this way, magnetic recording and reproduction are performed.

On the other hand, if you want to remove the cassette 93, push button 82
If is pressed, the slide frame 78 advances. Then, since the peripheral edge of the slanted long hole 83 pushes the roller 90, the roller 90 is pushed up and the cassette guide 87 is also pushed up to return to the original position.

When the cassette guide 87 rises and the roller 90 also rises, the slide plate 84 moves to the right as shown in FIG. 13 due to the tensile force of the spring 86 because it is located above the opening 85.
The roller 90 moves to the horizontal part of the opening 85, and the step
Get on the 85a. Due to the operation of the slide plate 84, the bent portion 8
Since 4b pushes the cassette 93, the cassette 93 can be pushed out from the end of the cassette guide 87 toward the front side and taken out.

By the way, slide frame 78, slide plate 84, cassette guide
87 is the chassis 1 in the assembled state as shown in FIG.
It is arranged inside the side plates 2 and 2, and is easily assembled by simply fixing the rollers 79 and 79a in the long holes 4 and the notches 5 with the screw 79b on the side surface of the slide frame 87. You can The pad arm 54 may be finally attached to the head base 30 side.

By the way, a block diagram of a control circuit is shown in FIG.

The magnetic disk device according to the present invention is controlled by the computer 100. The computer 100 and the magnetic disk device side are connected by electric wires, and when the input and output lines are combined, they are connected by about 34 electric wires.

These 34 input / output lines are all processed with digital signals.

On the other hand, the control circuit on the magnetic disk device side is roughly classified as shown in FIG. 19 (A) so as to be connected to the computer 100 and to amplify and digitize the outputs of the magnetic disk device side and various sensors, or It is mainly composed of a digital processing circuit 101 such as a pulse motor drive circuit for positioning the magnetic head on a predetermined track.

This circuit 101 includes a read amplifier 102, a write amplifier 103, a read amplifier for amplifying a signal obtained by reading information from the magnetic head,
A write switch 104, an index amplifier 105 that generates one pulse signal when the magnetic disk makes one rotation, a track position detection amplifier 106 that detects the track position of the magnetic head, a motor drive circuit 107 that rotates the magnetic disk, etc. Are connected.

Reference numeral 108 denotes a speed control circuit for controlling the number of rotations of the motor, which is connected to the motor drive circuit 107, and the signal lines 109, 1 from the digital processing circuit 101.
Speed control is performed by 10 as described later.

Further, reference numeral 111 is an amplifier for monitoring the motor rotation speed.

Reference numeral 112 indicates a television.

By the way, in the present invention based on the circuit configuration as described above, in addition to the general disk rotation speed at the time of recording and reproduction at the same rotation speed, high-density recording can be performed and recording is performed to improve reliability. And the structure that changes the motor speed during playback is adopted.

That is, first, when information to be recorded is input from the computer 100 to the digital processing circuit 101 as a command, the circuit 101 inputs a signal to the switching switcher 104 to switch the magnetic head from the reproducing mode to the recording mode and the write amplifier 103. To the operating state.

Further, after instructing the low speed rotation operation to the speed control circuit 108 via the signal line 110, it is confirmed from the amplifier 111 that the signal interval and the speed control interval time match, and the low speed rotation state is confirmed. A recording signal from the computer 100 is input to record information on the magnetic disk.

On the other hand, when a reproduction command is issued from the computer side, the read / write changeover switch 104 is changed over to the read side, the read amplifier 102 is operated, the speed control circuit 108 is set to the high speed mode via the signal line 109, and the amplifier 111 is turned on. After confirming that the motor is in the high-speed rotation state through the above, the reading of the record is started and input to the computer 100.

Further, when it is desired to make the number of rotations at the time of recording and reproduction the same, it can be processed by setting the reference frequency for setting the reference high speed rotation of the speed control circuit 108 to the same frequency as the low speed rotation.

FIG. 19 (B) shows the rotational speed of the magnetic disk from 300 rpm to 600 r.
The output characteristics are shown when the output of the magnetic head is measured when information is read instead of pm.

When the recording frequency f = 125 kHz and the disk rotation speed was set to 300 rpm, the magnetic head output was adjusted to 0.8 V, and when this point P was set as the origin and the rotation speed was doubled to 600 rpm, the magnetic head output almost doubled to Q point. .

Further, when the recording frequency f is doubled to 250 kHz, the magnetic recording density is increased, so that the origin is about 25% lower than the point P and the output at the point S is obtained.
An R point, which is an output about twice that of the point, was obtained.

When the magnetic disk is rotated at 300 rpm and magnetic recording is performed at a frequency of 250 kHz based on this output characteristic, 0.6 V of the S point is obtained when reproduced at that number of revolutions. When the rotation speed was set to 600 rpm, an output of 1.2 V at the R point was obtained.

In other words, a positive output voltage of 0.6 V will be obtained, and even if there is a drop in output due to variations in the characteristics of the magnetic disk, or a drop in output due to loss in the magnetic circuit of the magnetic head, there will be sufficient output voltage for digital processing. It was obtained and the reliability could be improved.

By the way, when recording the image signal of the revision 112 on the magnetic disk, when recording one screen of the cathode ray tube, if the magnetic disk is set to 3600 rpm, one field can be recorded on one track and one screen can be recorded.

It should be noted that one screen and one field means 1 second / 60 sheets screen = 16.7 ms.

By the way, since the frequency for recording a television image on a magnetic disk is 6.1 MHz, as explained in FIG. 19 (B), the output should increase if the number of rotations is set to 3600 rpm / 300 rpm = 12 times, but recording The frequency is 6.1MHz ÷ 250kHz = 24 times, the recording density is increased and the amplifier output is approximately 0.4 to 0.5V. Therefore, it is possible to reliably record and reproduce TV images on the magnetic disk by rotating the disk at high speed. .

By the way, the electronic components forming the control circuit shown in FIG. 19A are mounted on three substrates as shown in FIGS. 17 and 18.

That is, the above-mentioned printed boards 65 and 113, 114.

Printed circuit board 65 has an index, track position detection,
It is equipped with a motor drive circuit.

Further, the substrate 113 is equipped with a read / write changeover switch for the magnetic head, a read amplifier, and a write amplifier.
The interface-related circuits for processing the signals from the boards 65 and 113 are mounted on.

Further, a connector 115 is provided on each of the boards 65 and 113, and a connector 116 coupled to these is provided on the board 114 side so that the boards can be easily connected.

As shown in Fig. 18, the boards are mounted on the top, bottom, and sides of the chassis, so adjustment and confirmation of electrical signals can be done easily from the outside of the chassis. Easy to repair by replacing.

By the way, the magnetic disk device is used as a recording device of a computer, but in this case, there are parts that generate a strong magnetic field such as a cathode ray tube, a power transformer, and a motor in the vicinity of the device, and it is necessary to protect the device from these magnetic fields. is there.

Therefore, in the present invention, the chassis 1 is formed in a U-shape, and its upper surface and side surfaces are covered with an iron slide frame 78, a slide plate 84, and a cassette guide 87 to block an external magnetic field, thereby providing a large magnetic shield effect.

FIGS. 20 (A) to 20 (D) are for explaining the tracks of the magnetic disk. Although eight tracks are shown in the figure, actually 40 tracks can be recorded.

FIG. 20 (B) shows the tracks [0 to 2] in an enlarged manner. The track width a is 50 μm, the track interval b is 70 μm, and the track pitch is a + b = 120 μm.

In this way, when the track interval b is larger than the track width, if the data can be recorded between the tracks, 40 tracks can be increased to 80, and the recording capacity can be doubled.

Fig. 20 (C) shows a state in which the capacity is doubled in this way.
Shown in.

In FIG. 20 (C), a = 50 μm, b = 10 μm, and the track pitch is a + b = 60 μm.

By the way, when the track interval is reduced in this way, magnetic recording interference occurs between adjacent tracks.

Therefore, in the present invention, as shown in FIG. 20 (D), a method of magnetic recording by using two azimuth heads and alternately changing the recording direction is adopted.

On the other hand, the reproduction output was measured with the magnetic head 47 displaced from the outer circumference to the inner circumference at intervals of 10 μm with respect to the magnetic disk shown in FIG. 20 (D), and the result was as shown in FIG. 21 (A).

This reproduction output voltage is obtained by measuring the output of the read amplifier 102. Finally, this reproduction output voltage is input to a digital processing circuit, shaped into 5V peak-to-peak pulses of TTL level, and coupled with a computer or the like.

Therefore, when inputting the output shown in Fig. 21 (A) to the digital processing circuit, set the input level to 0.4V and generate a pulse when the input voltage is 0.4V or higher, and do not generate a pulse when the voltage is lower than that. If it is set, a normal digital signal is generated even if the amount of deviation between the center of the track and the magnetic head is ± 25 μm as shown in FIG. 21 (A).

Therefore, the total amount of dimensional deviation is allowed to be ± 25 μm due to the deflection of the motor shaft, the error of the radius of the cam 26, and the expansion and contraction of the magnetic disk due to temperature and humidity.

On the other hand, FIG. 21 (B) shows the output when the double-density track shown in FIG. 20 (C) is reproduced.

In FIG. 21 (B), the curve A shows the output characteristics of the track [0] when the track [1] is not magnetically recorded, and the curve B is the track [1] when the track [0] is not magnetically recorded. The measured characteristics of the output are shown.

When information is recorded on the tracks [0] and [1] and the magnetic head is moved from the track [0] direction to the track [1] direction for measurement, the output as shown by the curve C between the curves A and B is output. Is played.

That is, information interference occurs.

When the voltage in the shaded area surrounded by the curves A, B, and C is measured, it can be seen that the curves A and B are not completely summed to form the curve C, but other noise components are mixed. It

Therefore, the portion of the curve C is not accurate information.

In such a case, as shown in FIG. 21 (B), the deviation amount between the track and the magnetic head is 1/2 of that of FIG. 21 (A) ± 1.
The limit is about 2 μm, and the input level to the digital circuit must be set to 0.65V.

That is, in order to double the amount of information by the recording method as shown in FIG. 20 (C), the dimensional accuracy must be doubled or more, and high-precision and expensive parts are required.

Therefore, in the present invention, the recording method as shown in FIG.

That is, θ ₁ for each track in which the head gap is adjacent
Recording was carried out by using those that were oriented in different directions alternately with = θ ₂ .

Note that θ ₁ = θ ₂ = 10 degrees.

The structure of such a magnetic head is shown in FIG.

In FIG. 22, reference numerals 117 and 118 denote core halves constituting one magnetic head core, and θ is formed at the abutting portion of the two.
Gap G ₁ having a _first angle is formed.

Also, those shown at 119 and 120 gap G ₂ is the butt portion therebetween having an angle theta ₂ in the core halves constituting the other of the magnetic core is formed.

These cores are supported by a core support 121, and coils 122 are wound around the core halves 117 and 119.

The core support 121 is made of a resin containing a large amount of a glass material 123 that adheres between the cores or a glass material having an expansion coefficient substantially equal to that of Sendust, which is the material of the core, and is resistant to environmental changes such as vibration and temperature. It has a structure that can be completely extinguished.

Now, after magnetically recording the same information on the tracks [0 to 2] and moving the head composed of the core halves 117 and 118 shown in FIG. 22 by 10 μm from the track outer peripheral direction to the inner peripheral direction, the reproduction output voltage is measured. The output characteristic of the curve A shown in FIG. 21 (C) was obtained.

In the characteristic indicated by the curve A, the output voltage is small in the track [1] portion because the track [1] is recorded by the magnetic head having the inclined gap of θ ₂ .

That is, since the gap in which the track [1] is recorded is different from the gap of the head that is now passing by 20 degrees, the output is small and the noise component increases.

On the contrary, a head side composed of the core halves 119 and 120 is used to move from the track outer peripheral direction to the inner peripheral direction to measure the reproduction output, and an output like a curve B shown by a broken line in FIG. 21 (C) is obtained.

At this time, the optimum reproduction output voltage is obtained at the track [1] portion.

In this way, magnetic recording and reproduction are performed by an azimuth head having a gap inclined by θ _{1 for} even-numbered tracks including 0 and a gap inclined by θ _{2 for} odd-numbered digits, whereby magnetic recording information between adjacent tracks is recorded. Very little interference.

Therefore, if the input level is set to 0.4 V, the amount of deviation between the recorded track and the magnetic head is allowed to be 25 μm.

In this way, it is easier to perform high-density recording by using the magnetic head with the gap angle θ oriented in the opposite direction, the mechanical dimensional accuracy is easier, the design is easier with the simple mechanism, and the compatibility of the magnetic recording medium is increased. become.

23 (A) and 23 (B) explain another example of the structure of the magnetic head. In this embodiment, the magnetic heads 124, 126 are separated by a predetermined distance b as the magnetic heads 124 and one set of magnetic core halves 125, 126 is formed. It is arranged and attached to the head stand 127.

The thickness a of the core halves 125 and 126 is 50 μm, the interval b is 2.5 mm, and each is made of sendust and the gap G = 0.1 μm.
Glass is welded at m and the coil 128 is attached using the winding window 129.

When a magnetic head having such a structure is used, FIG.
When the configuration as shown in (1) is performed, recording and reproduction can be performed on tracks [0 to 19] on the core half body 125 side and on tracks [20 to 39] on the other core half body 126.

Therefore, when such a magnetic head 124 is used, in order to record and reproduce 40 tracks, it is possible to cover the whole by operating the head base 12 by 20 steps by the pulse motor 8.

In this case, the number of stages of the cam 26 is 20.

For example, in the case of a magnetic head without one core, when calculating the time when it is desired to change to tracks [0 to 20], the speed characteristic of the pulse motor is 3 ms for one track, so 20 x 3 ms = 60 ms. .

Further, even if the magnetic head arrives at the twentieth track, the pulse motor 8 does not stop suddenly but slightly vibrates, so it is necessary to wait until it stops before recording and reproducing. Therefore, recording and playback can be started only after about 70 ms.

On the other hand, if the head shown in FIG. 23 is adopted, after recording / reproducing the track [0], the track [2] is immediately reproduced without waiting time.
0] can be recorded and played back.

Furthermore, with a head with one core, recording / playback for tracks [0-39] is 3ms x 39 + 10 (1 hour waiting) = 127ms
In the case of the head shown in Fig. 23, 3 ms
Since x19 + 10 (waiting time) = 67ms, a difference of 60ms occurs, and it was found that high speed can be realized.

Next, a magnetic disk cassette applied to the magnetic disk device according to the present invention will be described.

Cassette 93 is the upper and lower cassette halves as shown in Fig. 25.
A magnetic disk 94 which is composed of 130 and 131 and has a center hub 95 between them is accommodated. Each cassette half has a through hole 132 into which the center hub 95 is fitted, and the head window 1
33 are formed respectively.

The reference numeral 134 indicates an arrow for indicating a cassette mounting method, and the reference numeral 135 indicates a concave portion to which a label 136 for writing a program name or the like is attached.

Further, reference numerals 137 and 138 are positioning holes into which the projections 7a at the upper ends of the pins 7 are fitted.

By the way, reference numeral 139 is a shutter fitted to the outside of the cassette halves 130 and 131 that are vertically aligned, and has a U-shaped cross section, which is slidably fitted so as to be sandwiched from the outside of the cassette.

At one end of the shutter 139, a protrusion 141 slidably fitted in a groove 140 formed on the upper surface on the cassette half 130 side is formed.

In addition, the bent portion 142 faces inward while facing the protrusion 141.
Are formed.

This bent portion 142 is a groove 1 formed in the upper and lower cassette halves.
It is fitted in 43, 144 and guides the shutter 139.

Further, a pin 145 is provided so as to project from the inner end of the groove 144 of the lower cassette half 131, and the pin 145 and the bent portion 142 are provided.
A spring 146 is stretched between and to give a force to draw the shutter 139 toward the center of the cassette half.

It should be noted that a stepped portion 147 that is one step lower for guiding the bent portion 142 is formed along the side edges of the grooves 143, 144 of the cassette halves 130, 131.

On the outer surface of each cassette half 130, 131 is formed a quadrangular recess 148 in contact with the shutter 139.

Further, the reference numeral 149 is a stopper for preventing the shutter from coming off.

Also, the reference numeral 150 indicates a cassette guide 87
It is a groove for passing a bent portion 87d for opening a shutter protruding at the entrance end in the cassette guide 87 when it is inserted into the cassette guide 87 when the cassette is inserted.

As shown in FIG. 28, the bent portion 87d contacts the end edge 139a of the shutter 139 when the cassette is mounted, and opens the shutter 139 with the head window 133 closed.

The state in which the shutter is closed is shown in FIGS. 26 (A) and (B), and the state in which the shutter is open is shown in FIGS. 26 (C) and (D).

Since the magnetic disk cassette used in the magnetic disk apparatus according to the present invention is constructed as described above, the shutter which is always closed can be automatically opened by simply inserting it into the cassette guide on the apparatus side to perform magnetic recording. Reproduction can be reliably performed.

[Effect] As is clear from the above description, according to the magnetic disk device of the present invention, the iron plate member is bent at both ends thereof to form the chassis having the bottom plate and the two side plates, The two side plates of the chassis are engaged with the engaging portions on the side surfaces of the cassette guide to move from the attaching / detaching position separated from the magnetic disk and the attaching portion of the magnetic disk to the attaching position for attaching to the attaching portion, and vice versa. And a bottom surface plate of the chassis as a yoke of a motor for rotating the magnetic disk mounted on the mounting portion and projecting from the rotor of the motor in the plate surface direction. However, since the head and the plurality of cassette supporting portions are provided in the projecting portion, the structure of the magnetic disk device can be simplified and the device can be easily downsized. It becomes possible.

[Brief description of drawings]

FIG. 1 illustrates an embodiment of the present invention. FIG. 1 is an exploded perspective view of a disk and a head drive mechanism, FIG. 2 is a perspective view of a chassis in which the head drive mechanism is mounted, and FIG. 2 is a sectional view taken along the line AA, FIG. 4 is a sectional view taken along the line BB of FIG. 2, FIG. 5A is a sectional view showing one bearing structure of the head base, and FIG. 5B. Is a cross-sectional view showing another example of the bearing structure, FIG. 5 (C) is a cross-sectional view showing the other bearing structure of the head base, and FIG. 5 (D) is a cross-section taken along line CC of FIG. 5 (C). Figure,
6 and 7 are explanatory views showing the structure of the cam and the structure and operation of the outermost track outermost position detecting mechanism, FIG. 8 is an exploded perspective view of the cassette mounting mechanism, and FIG. 9 is the cassette mounting mechanism in the assembled state. FIG. 10, FIG. 10 is a sectional view of the cassette mounting mechanism immediately after inserting the cassette, FIG. 11 is a sectional view of the cassette mounting mechanism in a completely mounted state, and FIGS. 12 (A) to 12 (G).
Is an explanatory view showing the operation of the rollers during cassette loading operation, FIG. 13 is a sectional view of the cassette loading mechanism before the cassette is lowered, FIG. 14 is a sectional view of the cassette loading mechanism after the cassette is lowered, and FIG. 15 is a cassette loading FIG. 16 is a perspective view showing the relationship between the mechanism and the chassis, FIG. 16 is a perspective view of the chassis with the cassette mounting mechanism attached, FIG. FIG. 19 (A) is a side view of the chassis in which the is mounted, FIG. 19 (A) is a block diagram of the control circuit, FIG. ) Is an explanatory view of a track of a magnetic disk, FIG. 20 (B) is an explanatory view of a roughly recorded track, FIG. 20 (C) is an explanatory view of a densely recorded track, and FIG. 20 (D) is a book. Explanatory drawing of the recording system adopted by the invention, FIGS. 21 (A) to 21 (C) Figure 20 (B) ~ graph showing the reproduction output characteristics respectively corresponding to the recording state shown in (D), Figure 22 (A) is a plan view of the magnetic head, FIG. 22 (B)
22A is a cross-sectional view taken along the line DD of FIG. 22A, FIG. 23A is a plan view showing another configuration example of the magnetic head, and FIG.
24A is a sectional view taken along line EE of FIG. 24A, FIGS. 24A and 24B are sectional views and explanatory views for explaining details of the track positioning mechanism, and FIG. 25 is an exploded perspective view of a magnetic disk cassette. 26
Figures (A) and (B) are plan and side views of the cassette with the shutter closed, and Figures 26 (C) and (D) are plan and side views with the shutter open, and Figure 27 is FIG. 26 (A) is an enlarged sectional view taken along the line FF, and FIG. 28 is a perspective view for explaining the opening operation of the shutter. 1 ... Chassis, 2 ... Side plate 65 ... Printed circuit board, 65a ... Coil 68 ... Yoke, 70 ... Permanent magnet

Claims (1)

[Claims] 1. A magnetic disk device for rotating a magnetic disk housed in a cassette and bringing a head into contact with the magnetic disk to record or reproduce information, wherein the cassette is held in the device. A cassette guide having an engaging portion formed on a side surface thereof; a mounting portion to which the magnetic disk is mounted; and a plurality of cassette supports capable of supporting the cassette when the cassette is mounted to the mounting portion. A chassis that has a bottom portion formed by bending an iron plate-shaped member at both ends and two side plates, the motor being connected to the mounting portion and rotating the magnetic disk. The side surface plate of the chassis 2 is engaged with an engaging portion on the side surface of the cassette guide to move the magnetic disk from the attaching / detaching position separated from the attaching portion to the attaching portion. A guide groove for transferring to a mounting position for mounting and vice versa is formed, and a bottom plate of the chassis is a yoke of the motor,
Further, the magnetic disk device is formed so as to be projected by the rotor of the motor in the plate surface direction, and the head and the plurality of cassette supporting portions are provided in the projected portion.