JPS593754A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To perform accurate tracking, by providing a cam driven by a pulse motor in contact with a roll fitted to a carriage pressed in a specific direction, and making its cam surface continuity of step difference as many as tracks. CONSTITUTION:The roll 15 is fitted to the carriage 11. The pulse motor 16 rotates a gear 39 and the cam 40 fitted rotatably on the shaft 8 of a motor 7 by a bearing 41 through gears 17 and 18 and a pinion 19. The cam 40 has the step parts which vary stepwise on the peripheral surface and the number of the steps is equalized to that of the tracks; and they abut said roll 15 to move the carriage 11, track by track, synchronously with the output of the pulse motor 16. Thus, the accurate tracking is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device configured to enable accurate tracking of a magnetic head in a small magnetic disk device using a small diameter magnetic disk. It is related to.

Floppy disk devices, which are widely used as storage devices using magnetic disks, are used in various electronic devices such as robot equipment, personal computers, word processors, electronic typewriters, and pocket computers, and are useful for increasing the added value of these devices. ing.

With the miniaturization of devices in this type of magnetic disk device, for example, magnetic recording media with a diameter of about 50 mm, that is, magnetic disks (floppy disks) are used, and small magnetic disk devices are used to enable high-security storage. Demand for discs is increasing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized magnetic disk device as described above, in which tracking of a magnetic head can be performed accurately.

In order to achieve the above-mentioned object, the present invention provides a roller on a carriage that is applied with a pressing force in a certain direction, and a cam that is rotated by a pulse motor while in contact with the roller to move the carriage. , we adopted a structure in which the cam surface of this cam is constructed as a series of stepped sections of the same number as the number of tracks.

Below, the present invention will be described in detail based on the drawings.

FIG. 1 and the following illustrate a magnetic disk device to which the present invention is applied, and FIG. 1 shows an exploded schematic configuration thereof.

The magnetic disk device according to the present invention can be roughly divided into five parts: a base portion l, a position detection mechanism 2, a holder portion 3, a disk holding mechanism 4, and a magnetic disk cassette 5 (hereinafter referred to as , magnetic disks are called floppy disks).

The base 1 constitutes the main part of the floppy disk device, and is provided with a magnetic recording/reproducing head and a driving source.

The position detection mechanism 2 detects the track position and detects the track position.
is a floppy disk cassette (below).

A cassette (abbreviated as a cassette) 5 is detachably attached thereto and plays the role of correctly guiding the floppy disk to the head provided on the base side.

Further, the disk holding mechanism 4 exerts a pressing force on the floppy disk, and serves to bring the head and the floppy disk into contact with an appropriate pressing force.

The details of each part will be sequentially explained below.

The base section 1 is assembled with a base 6 as a reference, and is provided with a motor 7 for rotating a floppy disk, the output shaft 8 of which is arranged vertically.

Two guide rails 8 and 10 are horizontally suspended in parallel on the base 6 so as to sandwich the motor 7 therebetween. A carriage 11 is slidably fitted into lO. Coil springs 12 are attached to the guide rails 8 and 10.
13 is attached to apply a pressing force to the carriage 11 in a direction toward the output shaft 8 of the motor 7.

A magnetic head 14 for recording and reproducing is fixed on the carriage 11, and a roller 15 for tracking in conjunction with a positioning mechanism to be described later is attached to the lower surface of the front side of the magnetic head 14.

A pulse motor 16 for driving the head is attached to one corner of the base 6, and a gear 17 fixed to its output shaft meshes with a gear 1 rotatably supported near the pulse motor 1B. A pinion gear 19 is integrally provided on the lower surface of the gear 18.

Above the motor 7 is the pinion gear 18. motor 7
The printed circuit board 2° is attached while avoiding the output shaft 8 of. This printed circuit board 20 has a through hole 20a at the - corner, and this through hole 20a is fitted into a bottle 21 protruding from the base 6, and is fixed in a state in which the top and bottom are sandwiched between E-rings 22. be done.

The corner facing the through hole 20a is fixed to the upper end of the side wall 24 of the base 6 with a screw 23, and the other end is also fixed to the base 6 via a screw.
fixed to the side wall or partition wall soil.

On the printed circuit board 20, photodetectors 25 and 2Ei each consisting of a light receiving element and a light emitting element are attached on the upper and lower sides.

By the way, the motor 7 has a structure as shown exploded in FIG. 3. The motor 7 has a rotor 27 formed by pressing a magnetic metal such as an iron plate into a flat cylindrical shape, and has permanent d-stones 28 and 29 inside the rotor 27 as shown in FIG.
are fixed at equal angular intervals. These permanent magnets 28.2
No. 9 is molded from synthetic resin mixed with magnetic powder, and is excellent in mass production.

The output shaft 8 is fixed to the rotor 27, and a bearing fixed to a yoke 30 of the output shaft 8 is rotatably supported by two upper and lower bearings 32a and 32b fixed to a holder 31. Reference numeral 33 denotes a printed circuit board, which is arranged above the yoke 30, and on which six coils L are mounted, surrounding the through hole 33a into which the holder 31 fits.
, -L6 are provided, and when a current is passed through these coils L and -L6, a magnetic flux is generated, and in cooperation with the permanent magnets 28 and 28 of the rotor 27, the rotor 27
is rotated.

A disk 34 is fixed to the lower side of the rotor 27, as shown in FIGS. 3 and 4. A pattern 35 in which a total of six black and white zones are alternately arranged at equal angular intervals and a pattern 36 in which a total of 102 black and white zones are formed are concentrically formed on the lower surface of the disk 34.

The printed circuit board 33 corresponds to these patterns 35 and 36.
Photodetectors 37, 38 are fixed on top.

The photodetector 37 detects the pattern 3G and detects the rotor 27.
Detects the rotation speed. In addition, the photodetector 38 is connected to the coil L1.
-Detect the positional relationship between L6 and permanent magnets 28 and 29.

A detection circuit using these photodetectors and coils L1 to L6 is shown in FIG. In FIG. 5, LED 1 and Tr5 constitute a photodetector 38, and LED 2 and Tr6 constitute a photodetector 38.
constitutes a photodetector 37.

In FIG. 5, when the rotation start signal MOT ON of the motor 7 is input to the servo circuit IC2, the IC2 starts operating and the transistors Tr1. Tr3 or Tr2.

Turn on either one between Tr3 and coil L 1 , L
3 +L5 or L2. L4. Current flows through L6, and the magnetic field from the permanent magnets 28 and 29 forms a magnetic circuit passing through the yoke 30, so repulsion and attraction alternately occur between the magnetic flux generated by the coil and the rotor 27. begins to rotate.

This rotation is detected by said photodetector 37,38.

Now, when the black color of pattern 3 is detected by the photodetector 38 consisting of LED and Tr5, the output of Tr5 flows to IC, Ic2 and is input to the base of Trl,
Trl is conductive and coils Ll, L3 . Current is supplied to L5. Also, when white is detected, the output of Tr5 is I
Turning on C1 causes current to flow through Tr2, causing it to coil.2. L
4. Current flows through L6. At this time, since IC2 is an inverter, the output is O, and Trl is OF
F, and no current flows.As a result, the coil L l
, no current flows through L 3 + L 5.

That is, by changing the information between LED 1 and Tr5,
Trl and Tr2 are alternately switched to cause current to alternately flow through odd-numbered coils and even-numbered coils.

By the way, since the rotor 27 needs to maintain a certain rotation speed, Trl and Tr2 are ON and 0FFC7.
) The Tr3 is used as a digital switch, and the Tr3 is used as an analog switch to control the current flowing through the coil and rotate the rotor 27 which has a built-in permanent magnet.

Servo IC3 is used to rotate the motor 7 at a constant speed,
A CR component such as a crystal oscillator is used as a part of the servo IC3 to oscillate a reference frequency with a precise pulse time interval, and this is input to the servo IC3 and the LED2
The rotation frequency, which is the detection result of the pattern 36 by the photodetector 37 consisting of the Tr 6 and the Tr 6, is input to the IC 3 and the mutual frequencies are compared. If the rotational frequency generated by rotation of the pattern 36 is lower than the reference frequency, a high current is applied to the base of the Tr3, and a large current is supplied to the coils Ll-L6 to increase the rotational speed. Further, if the rotational frequency is equal to or higher than the reference frequency, a low current is supplied to the base of Tr3, and a small current is supplied to the coils L and -L6 to lower the rotational speed.

In this way, the rotation speed of the rotor 27 is detected by the photodetector 37 and the pattern 36, and the servo IC 3 compares it with the reference frequency to control the base current of the Tr 3, thereby making the rotation speed constant.

By the way, specifically, the rotational speed of the rotor 27 during steady state is one rotation at 204 m5ec, and the number of passes of the pattern 35 to the photodetector 38 during one rotation of the rotor 27 is 6.
Therefore, the switching period of Trl and Tr2 is 204/6, which is 34 m5ec. Also, the standard pulse time interval for rotating the motor at a constant speed is 2 ffl
The base of the drive transistor 23 is controlled at intervals of sec. Therefore, pattern 36 is divided into 102 equal parts.
This allows the signal generation of IIISeC to be divided.

Since load fluctuations when a magnetic head contacts a floppy disk for recording and reproduction are relatively small, satisfactory rotation can be obtained even if the reference pulse time interval is increased to 2 m5ec or more. Rather, what is difficult is the accuracy of dividing the pattern 3B, the accuracy of the signal rise time of the photodetector 37, etc., and if these accuracy can be improved, there is no problem even if the reference frequency is lowered.

By the way, the permanent magnet 28°28 accommodated in the rotor 27
If it is formed from an integrally molded ring-shaped permanent magnet, the boundary between the magnetic poles becomes unclear during magnetization. Therefore, in this example, a split type is used, which reduces the mass of the entire permanent magnet and improves the distance between the magnetic poles. This creates a space between the parts and reduces the weight.

In addition, if such a rotor structure is adopted, it is quite possible that the permanent magnet material will be formed from expensive rare earth materials in order to downsize the motor in the future, so using split permanent magnets will save resources and cost. Connected to down.

Incidentally, a large-diameter gear 39 and a cam 40 are rotatably supported on the output shaft 8 of the motor 7 via a bearing 41, and the gear 39 meshes with the pinion gear 19, so that the rotation of the pulse motor 16 is controlled. communicated. When a single pulse is applied to the pulse motor 16, the gear 17 attached to its output shaft 8 rotates 18 degrees. This rotation is transmitted to the gear 38 via the gear 18 and pinion gear 18.

Incidentally, high precision is required for the dimensional accuracy of the relative positional relationship between the magnetic head 14 on the carriage II and the output shaft 8 of the motor 7.

The reason for this is that if the dimensional accuracy varies, compatibility between cassettes and cassettes will be lost, and recording and playback will become impossible if other cassettes are used.

Therefore, in order to reduce variations in dimensional accuracy between the magnetic head 14 and the output shaft 8, a cam 4 for driving the carriage is attached to the output shaft 8, which is the rotation center of the floppy disk.
It is optimal to install 0.

Further, by attaching the cam 40 to the output shaft 8 via a bearing 41 with excellent rotational efficiency, the influence exerted from the cam on the motor 7 can be reduced, thereby reducing the rotational load.

By the way, as will be described later, since the cam 40 is engaged with the roller 15 provided on the carriage, the vibration of the output shaft 8 is transmitted to the cam 40, the carriage 11 vibrates, and the vibration is transmitted to the magnetic head 14. However, since the floppy disk is also attached to the output shaft 8, the vibration of the magnetic head and the vibration of the floppy disk are synchronized, and the track position and dimensions do not go out of order.

Incidentally, in practice, when the pulse motor 18 is energized with three pulses, the angle of the cam 40 changes by 9 degrees, and the carriage 11 is set to move by one track.

However, due to the characteristics of a pulse motor, as shown in FIG. 7, when one pulse of electricity is applied, the axis of the pulse motor 16 changes! The displacement is 8 degrees, but when the second pulse is applied, the displacement should be 36 degrees, but due to the inertia and magnetization accuracy of the rotor, 61 rotations are exceeded. Also, when the third pulse is applied,
The planned displacement of 54 degrees is reduced by 62 degrees. Also, 4
Generally, the rotation stop position of a pulse motor varies slightly, such as when the pulse motor is energized, it rotates 72 degrees as planned.

Therefore, if the cam 40 rotated by the pulse motor 16 has a linear relationship between the rotation angle and the amount of displacement as shown in FIG. 8, a pulse motor with the characteristics shown in FIG. 7 can be used. In this case, the stop position of the carriage 11 varies at a rate of 2154 degrees, making it impossible to accurately stop the magnetic head on a predetermined track.

On the other hand, as shown in Figure 9, the relationship between rotation angle and displacement is
If a cam that changes stepwise is used, even if the stop position of the pulse motor is deviated by 62 minutes, the cam will not be displaced to the same extent as this, and variations in the stop position can be drastically reduced. In addition, even if backlash or eccentricity occurs between power transmission gears,
Errors caused by these can be absorbed, and the magnetic heald can be accurately aligned to a desired position. As a result, backlash can be provided between the gears in the rotational torque of the pulse motor, so it is possible to reduce the rotational torque and power consumption.

For this reason, in the present invention, a plurality of stepped cam surfaces 40a are formed on the circumferential surface of the cam 40, as shown in FIG. The number of these stepped cam surfaces 40a is 40, which in this embodiment is the same as the number of tracks on a floppy disk. Further, the circumferential surface of the cam 40 is on a spiral curve, and gradually becomes smaller from the short diameter part to the long diameter part, and the connecting part between the short diameter part and the long diameter part is a straight part 40b, and the base of this straight part 40b is An arcuate recess 40c is formed.

By the way, if it is not always known which track position the magnetic head 14 currently corresponds to, recording and reproducing errors will occur. Therefore, when the magnetic head is located at a position corresponding to the maximum diameter track of the floppy disk, a reference signal is generated from the device side, and the correspondence state with other track positions is determined by determining the number of pulses energized to the pulse motor 16. We devised a configuration in which the position of the magnetic head is determined by storing it in a control circuit (not shown). This is the disk 4 that constitutes the detection mechanism section 2.
It is 2.

As shown in FIGS. 1 and 23, the disc 42 is mounted on the gear 39 so as to be rotatably fitted onto the boss 43. A detection piece 42a is provided protruding from a part of the disk 42, and is structured to reflect light by being plated or pasted with aluminum foil or the like. This detection piece 42
a is detected by a photodetector 25 provided on the bottom surface of the printed circuit board 20, and a pulse signal is transmitted once per rotation. Therefore, if this detection piece 42a is arranged so that it is detected by the photodetector 25 when the magnetic head 14 is at the maximum diameter track position, that position can be detected.

Of course, it is possible to provide a detection piece directly on the magnetic head 14 so that the position of the magnetic head can be known, but in this embodiment, the moving distance per track is 0.125 mn.
+, and the change in the electrical output of the photodetector is minute, requiring an expensive circuit and being impractical.

However, in the present invention, the detection piece 42a rotates slowly together with the gear 38, and the amount of movement per track is approximately 2.
．． 5 m1Ilf'J, so it is an inexpensive photodetector 25
This makes it possible to detect the track position, that is, the head position.

On the other hand, although the cam 40 is mounted on the gear 3s together with the disc 42, positional deviations occur due to processing errors and mounting errors, and the above-mentioned detection function may not be fully exerted. For this reason, in the present invention, arc-shaped long holes 42b are provided in the disc 42 facing each other, and screws 44 that are screwed onto the gear 39 are fitted into these long holes 42b, so that the disc 40 can be rotated. In this way, the position of the detection piece 42a can be finely adjusted. To perform this fine adjustment, an eccentric pin gauge 101 as shown in FIG. 23 is used. This eccentric pin gauge 101 has an eccentric pin 101a at the lower end. If the diameter of this eccentric pin gauge +01 is D and the width of the long hole 42c in the radial direction formed in the circular plate 42 is W, it is set so that D=W, and the small hole into which the eccentric pin 101a fits. 3
9a is formed on the gear 38 side facing the long hole 42c.

Therefore, by fitting the eccentric pin gauge 101 into the elongated hole 42c, fitting the eccentric pin 101a into the small hole 39a, and rotating the eccentric pin gauge 101, the disc 42 can be rotated left and right, and the detection piece Fine adjustment of the position of 42a becomes possible.

In the present invention, the tracks of the floppy disk are divided into 40 equal parts with a radius of 15+am to 2hm, and one track is 0.
．． It was set to 125 mm. Therefore, the magnetic head will rotate between 15 mm and 20 mm with the output shaft 8 of the motor 7 as the center.
Unless the floppy disk is driven accurately at a pitch of 125 square meters, floppy disks recorded with other devices cannot be used.

Also, if the maximum track diameter position 2o2 and the minimum track diameter position 15 mm of the magnetic head are not accurate, the specifications will not be common to other devices. Therefore, the magnetic head 1 is
The dimensional tolerance of each part between 4 and 4 cannot be ignored.

The mounting structure of the roller 15 solves this problem. The mounting structure of the roller 15 is shown in FIGS. 11 to 13. That is, the roller 15 is
It is mounted eccentrically via the shaft 15a. This amount of eccentricity is δ. The screw shaft 45 has a groove 45a at its upper end.
A screwdriver or the like is inserted into this and screwed into a screw hole 11a formed in the carriage 11.

Therefore, when the screw shaft 45 is rotated, the center of the roller I5 can be rotated with a radius δ, and the distance between it and the cam 40 is
That is, the distance between the output shaft 8 to which the cam 4o is fixed and the magnetic head 14 can be reliably finely adjusted. After finishing the fine adjustment, tighten the lock nut 4 on the upper end of the screw shaft 45.
6 and fix it in that position. In this way, variations in processing accuracy and mounting accuracy are absorbed and adjusted.

As shown in FIG. 1O, the cam 40 has a plurality of through holes 40e formed around a central hole 40d into which the output shaft 8 is fitted, and a shaft 43a protruding from the post 43 into these through holes 40e. are fitted and fixed by directional pressure such as caulking.

A disk 47 is attached to the upper end of the output shaft 8. The disk 47 has a post 48 on its upper surface, and a cylinder 49 on its lower surface.
This cylinder 48 is fitted onto the upper end of the output shaft 8 and fixed by screwing the screw 50 from the side.

A disk 51 is fitted into this cylinder 48 between the disk 47 and the cam 40 through its center hole 51a, and the pin 5
It is fixed by caulking 1c. The disc 51 has a detection piece 51b protruding from its circumferential surface. This detection piece 51b is formed as a reflector so that it can be detected by another photodetector 26 provided on the upper surface of the printed circuit board 20.

An arc-shaped spring piece 52 is punched out in a part of the date plate 51, and the upper surface of the free end side (this is the pin 5
3 is installed protrudingly. The pin 53 is inserted into a through hole 47a formed in a part of the disk 47, and
He will appear above 7. This pin 53 is fitted into a through hole formed in the rear hub, and transmits the rotation of the output shaft 8. This disk 51 is fixed to the post 43 together with the cam 4o.

A detection piece 51b protruding from the disc 51 is detected by the photodetector 26 every rotation of the output shaft 8 and generates a start position signal.

On the other hand, the holder portion 3 has a structure as shown exploded in FIG.

That is, the holder portion 3 is assembled based on the substrate 54. The substrate 54 is press-molded from a metal plate, and side plates 55 are formed on both left and right sides thereof. These side plates 5
Through holes 55a are formed at opposite positions on the distal end side of the shaft 5, and a shaft 56 is fitted into these through holes. Both ends of the shaft 56 are rotatably fitted into through holes 6a formed in the left and right side plates of the base 6.

Further, a projecting piece 57 is provided in the center of the side plate 55,
A spring 58 is stretched between this protruding piece 57 and a protruding piece 6b protruding from the base 6.
It provides a pulling force to the base 6 side.

A through hole 54a into which the disk 47 can be inserted is formed in the center of the substrate 54, and an elongated hole 54b into which a magnetic head can be inserted is formed on the side of the hole 54a.

Bent pieces 54c, 54c bent upward are formed on the free end side edge of the substrate 54, and bent pieces 55b are formed on the edge of the side plate 55 in a state of expanding from side to side.
Furthermore, a bent piece 55c bent downward is formed below the bent piece 55b.

These bent pieces 54c, 55b, and 55c serve as guides when the cassette 5 is mounted.6 Furthermore, guide pieces 55d for guiding the cassette 5 are formed at the lower ends of the side plates 55, respectively.

Levers 59 and 130 are attached to the outside of the left and right side plates 55. These 8-59 and EIO have through holes 59a and EIOa formed in the center along the longitudinal direction, and guide pins 61 fixed to the protrusion 57 are fitted into these through holes, respectively. be done. Each lever 59.
a protrusion 59b protruding downward from the tip of 80;
A spring 62 is stretched between 80b and the protruding piece 57, and pulls the levers 5f3 and 80 to the front side.

Notches 59c and 60c are formed in the front edge of each lever 59 and 130 along the longitudinal direction, and a guide pin 63 fixed to the side plate 55 is fitted into these notches. .

In addition, L-shaped bent portions 59d and 80d are formed at the tip of the lever 59.60 at a right angle toward the board 54, and these bent portions 58d, [(Od is the side plate 55 into the notch 55e formed on the upper surface of the tip, the tip faces the inside of the side plate 55, and the case and
When the cassette 5 is installed, both sides 5a, 5 of the tip of the cassette 5
b.

Further, each lever 59.80 has a projecting piece 5 on the near side edge.
8e and 60e are provided protrudingly, and these protruding pieces 59e
.

60e is located at a position where it can engage with one of the guide rails 10 provided on the base 6 side.

Also, between the protruding pieces 513b and 59e of each lever 59 and 6
0b.

Between BOe are guide portions 59f and 80f that come into contact with guide rollers of an operating lever, which will be described later.

By the way, a protruding piece 64 is provided on the tip of the base plate 54 at approximately the center thereof, and a lever 66 is rotatably supported at the center of the tip via a pin 65. This lever 66 is formed into a substantially "<" shape, and one end thereof has a bent portion 5 formed at the tip of the lever 58.
A pin 67 is slidably fitted into a long hole 59g formed in 9d and projects downward.

Further, a projection 68 that engages with a pad arm, which will be described later, is provided on the upper surface of the other end of the lever 8B.

On the other hand, the disc holding mechanism portion 4 is constructed as shown in FIG.

The disc holding mechanism 4 is composed of a leaf spring 69 and a pad arm 70. The leaf spring 68 is formed into a substantially quadrilateral shape, and a post 71a of a rotating body 71 is fitted into a through hole 69a formed in the center of the leaf spring 68 from below the leaf spring 68, and a boss 71a is fitted into the through hole 69a formed in the center of the leaf spring 68. 1a is a presser ring 72 located above the leaf spring 69
It is fitted into the through hole 72a and integrated with the presser ring 72 by a screw 73, and is rotatably attached to the leaf spring 69. An arcuate portion 71b is formed on the circumferential surface of the rotating body 71, and this portion is connected to the through hole 5 of the base plate 54 of the holder.
4a to ensure smooth insertion when the cassette 5 is installed. This rotating body 71 comes into contact with the hub of a floppy disk housed in a cassette, which will be described later, and plays the role of supporting the rotation of the floppy disk from above.

Three through holes f19b are formed in the leaf spring 68, and pins 74 protruding from the upper surface of the substrate 54 are fitted into these through holes f19b and fixed by caulking.

A spring piece 75 is protruded from the center of the tip of the leaf spring 68, and this spring piece 75 is fitted into the notch 54d formed in the base plate 54, and serves to hold down the cassette 5.

Also, spring pieces are attached to both left and right ends of the other end of the leaf spring 68.
[l, 7B is formed and serves to hold down the cassette 5 from above.

Note that the plurality of punched grooves formed between the through holes 89a provide elasticity to the portion surrounding the through holes 89a.
This is to elastically maintain the contact of the rotating body 71 with the hub of the floppy disk.

The pad arm 70 has a pad 77 on the lower surface of its tip, and a leaf spring 78 is connected to its base end.
It is fixed to a protruding piece 11a provided protrudingly from one end of 1. The pad 77 corresponds to the magnetic head 14, and the pad arm 7
There is a recess on the lower surface of the board 54 at a position that can correspond to the protrusion 68 of the lever 68 provided on the board 54 side. Oa is formed. The pad 77 passes through a notch 69d formed on the side edge of the leaf spring 68, fits into the elongated hole 54b of the substrate 54, is disposed facing the magnetic head 14, and presses the floppy disk from above.

On the other hand, the cassette 5 has a structure as shown exploded in FIG. 14.

That is, the cassette 5 has cassette halves 81 and 82 molded from synthetic resin or the like, and a through hole 8 into which the disk 47 and the rotating body 71 are inserted is formed at opposing positions in the center of the cassette halves 81 and 82.
1a and 82a are formed, and openings 81b and 82b into which the magnetic head and band are inserted are formed in the vicinity thereof. Inside the upper cassette half 81, a disc-shaped liner 83 is fixed at a plurality of locations indicated by reference numeral 83a via an adhesive or the like. This liner 83
has a through hole 83b at a position corresponding to the through hole 81a of the cassette half 81, and an opening 83c at a position opposite to the opening 81b. Spring pieces 84 and 85 are arranged between the liner 83 and the cassette half 81, sandwiching the opening 83c. Base end 84a of spring piece 84.85
, 85a is fixed to the lower surface of the cassette half 81, and its free end side holds the liner 83 on both sides of the opening 83c.
It's pushing downward. The role of these spring pieces 84, 85 is to press the liner 83 against the floppy disk on both sides of the magnetic head and band that sandwich the floppy disk from above and below, thereby maintaining reliable contact between the floppy disk and the magnetic head.

This state is shown in FIG.

Liners 813 and 86 are provided on the lower cassette half 82 side, sandwiching the through hole 82a, and a small hole 82c is formed at a position that does not come into contact with the front disk. The upper end portion of the pin 21 protruding from the base 6 side is fitted into this small hole 82c, which serves as a positioning hole for mounting the cassette.

A floppy disk 87 is accommodated between the liner 83 and the lower cassette bar 282. The floppy disk 87 has a hub 88 in the center, into which the post 48 of the disk 47 is fitted, and into which the spring piece 52 of the disc 51 protrudes into a through hole 88b formed near the center hole 88a. The provided pin 53 is fitted.

Incidentally, the base 6 side is devised to constitute a mounting reference surface when a cassette is mounted. That is, the 16th
As shown in the figure, the pin 21 protruding from the base 6 not only serves to attach the printed circuit board 2o, but also has a protrusion 21b protruding from the upper edge 2+a that fits into the small hole 82c of the cassette bar 282. Perform positioning. In addition, an upper edge 89a of a support 89.80 that is integral with or separate from the side wall of the base 6,
Ha is set to be in the same plane as the upper edge 21a of the pin 21, thereby forming a mounting reference plane. The pin 21 and the strut 88.80 have a triangular upper edge 89a, and a protrusion 8 on the outside of the oa! These projecting pieces 139b, 90b are provided with protruding pieces 139b, 90b, which are connected to the outer edge 5c of the cassette 5,
It plays the role of positioning 5d.

Therefore, when the cassette 5 is lowered together with the holder toward the base 6 by the operation described later, the cassette 5 is reliably supported on a certain reference plane by the pins 21 and the supports 811, 110, and also by the protrusions 21b and protrusions. 811b and 90b for accurate positioning.

By the way, an operating lever 91 is provided on the base 6 side. The operating lever 81 is formed as a substantially U-shaped frame and is rotatably supported on both sides of the front end of the base 6 via pins 82. A roller 93 is rotatably attached to the inner surface of the pin 92 at a position remote from the pin 92.

This roller 93 is located at a position in contact with the guide portions 59f, 60f of the levers 5!3, 60.

The operating lever 91 has the tendency to rotate clockwise in FIG. 1 about the pin 82 due to its own weight.

Next, the operating method and operation of the floppy disk device according to the present invention constructed as above will be explained.

Before the cassette 5 is installed inside the holder, the front end of the board 54 is lifted upward as shown in FIG.
It is in a state where it is pulled toward this side by the tensile force of 2. However, the lower ends of the protrusions 5!3e and 8Qe of the levers 511 and 130 are in contact with the guide rail 10, and do not descend even when the tensile force of the spring 58 is applied, but maintain this state.

At this time, the 8-81 is rotated toward the front and the roller 83 is rotated.
is in contact with the front corner of the guide portion 59f, EiOf.

In this state, the lever 66 is rotated in the counterclockwise direction in FIG.
As shown in the figure, the pad arm 70 is in contact with the back side of the lower surface of the four parts 70a, and the pad arm 70 is connected to the leaf spring 78.
The pad 77 is pushed up in a direction away from the substrate 54 against the pressing force.

In this state, when the cassette 5 is inserted into the guide portion formed by the bent pieces 54c, 55b, and 55c at the front end of the board 54, the tips 5a and 5b of the cassette 5 are moved to the lever 59. G.

When the levers 58 and 60 come into contact with the folded pieces 59d and Sod on the back side of the lever 59 and push the cassette 5 roughly in, the levers 58 and 60 move inward against the tensile force of the spring 62. The limit of this movement is the long hole 5
9a, f30a. In due course eight
5! a. As EiO moves forward, the protrusions 59e and 60e begin to move away from the guide rail IO, as shown in FIG.

At the same time, as the lever 58 moves forward, the lever 66 is rotated clockwise in FIG. 2 via the pin 67, and as shown in FIG.
It starts to fit inside.

As a result, the tip of the pad arm 70 is lowered by the force of the leaf spring 78, passes through the elongated hole 54b of the board 54, and fits into the opening 81b of the cassette 5, and the floppy disk 8
Begin contact with 7.

Eventually, when the levers 59 and 60 are pushed to the innermost side, the protrusions 5 of each lever are pushed in as shown in FIG.
9e and 6oe are separated from the guide rail 10, and the holder part 3 centered on the board 54 is pulled downward by the tensile force of the spring 58.

At this time, the protrusion 21b of the pin 21 is fitted into the small hole 82c formed on the back surface of the front end of the cassette 5, and the lower surface of the cassette 5 is fitted onto the edge 21a of the pin 21 and the upper edge of the support 88. are in contact with each other, and the cassette 5 is set on the reference surface. At the same time, the pillar 89. Both ends 5c and 5d on the back side of the cassette 5 are positioned and mounted in the left and right direction by the protruding pieces 88b and 90b.

In this state, as shown in FIG. 15, the floppy disk 87 is sandwiched between the pad 77 and the magnetic disk 14 from above and below, and is pushed through the liner 83 which is pressed on both sides by the spring pieces 84 and 85, so the floppy disk 87 is magnetically to rad 14
The floppy disk 87 is in a slightly curved state when it is sandwiched between the floppy disks 87 and 87, so that the floppy disk 87 is in secure contact with the magnetic head 14.

In this state, magnetic recording and reproduction are performed.

If you wish to remove the cassette 5, operate the cassette from the fully installed state as shown in FIG. 59. f(O is pushed upward and pulled back toward you by the force of the spring 62. Eventually, the projecting piece 59e of each lever
, 60e are separated from the guide rail IO, and the entire holder portion is locked with the front side raised.

At the same time, by moving the levers 59, 60 toward the front, the band arm 70 is also raised, and the cassette 5 is pushed back toward the front by a predetermined distance. If you pick up the case 5 and pull it out, the thing that restrains the case 5 is the spring piece 75 of the leaf spring 68.
．． Since it is only 76, it can be easily drawn out.

As is clear from the above description, according to the present invention, a roller is provided on a carriage that is pressed in a certain direction, and a cam that contacts this roller and is rotated by a pulse motor is provided, and the cam surface of this cam is tracked. Since a structure is adopted in which the same number of step portions are continuous, a magnetic disk device that can perform accurate tracking without being affected by the stopping characteristics of the pulse motor can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] The figures are for explaining one embodiment of the present invention, in which FIG. 1 is an exploded perspective view of the base portion, FIG. 2 is an exploded perspective view of the holder portion,
Figure 3 is an exploded perspective view of the motor, Figure 4 is a perspective view of the rotor seen from below, Figure 5 is a circuit diagram showing the connection between the photodetector and the coil, and Figure 6 is the base section. A side view, FIG. 7 is a diagram showing the relationship between the number of input pulses of the pulse motor and the rotation angle, and FIG. 8 is a diagram showing the relationship between the rotation angle and displacement amount of a general cam shown as a comparative example. FIG. 9 is a diagram showing the relationship between the rotation angle and displacement amount of the cam applied to the present invention;
The figure is a plan view of the cam, Figure 11 is an exploded perspective view showing the installation structure of the roller that the cam contacts, Figure 12 is a perspective view of the roller seen from below, and Figure 13 is the arrangement of the cam and roller. Fig. 14 is an exploded perspective view of the cassette; Fig. 14 is an exploded perspective view of the cassette;
Figure 5 is a partially enlarged vertical sectional side view of the cassette, Figure 16 is a perspective view showing the reference plane setting structure for mounting the cassette, Figures 17 to 18 are side views explaining the operation, and Figure 20 is the cassette. 21 and 2 are partial longitudinal side views showing the installed state of the
FIG. 2 is a side view illustrating the operation of the pad arm, and FIG. 23 is a perspective view illustrating a fine adjustment method using an eccentric pin gauge. 1... Base part 2... Position detection mechanism part 3.
...Holder part 4...Disc holding mechanism 5...
・Cassette 6...Base 7...Motor 8...
・Output shaft 8, 10...Guide rail 11・
... Carriage 14 ... Magnetic head 15 ...
Roller 16...Pulse motor 20...Printed circuit board 25.26...Photodetector 21...Pin 27...Rotor 2B, 29...Permanent magnet 34...Disk 40... Cam 47...
Disk 54...board 58, 60.88
... Lever 168 ... Leaf spring 70 ...
Pad arm 77... Para F 81, 82
... Kasent Half 83.86 ... Raina 8
7... Floppy disk 88... Hub 89.
90...Strut 91...Operate/Heh Figure 15 Figure 16 d Figure 17 Figure 20 Figure 21 Figure 0 Figure 22 Figure 23

Claims (1)

[Claims] In a magnetic disk device in which a magnetic disk cassette is removably attached, a roller is provided on a carriage pressed in a certain direction, and a cam rotated by a pulse motor is brought into contact with the roller to move the carriage. In addition, a magnetic disk device characterized in that the cam surface of the cam is constituted by a series of step portions of the same number as the number of tracks.