JPS593752A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To perform accurate tracking, by forming step parts as many as tracks of a magnetic disk on the peripheral surface of a cam fitted on a gear rotating together with the magnetic disk, and bringing the cam in invariable contact with a carriage-side roll. CONSTITUTION:The gear 39 and cam 40 for driving a carriage 11 are fitted rotatably to the shaft 8 of a motor 7 for rotating the magnetic disk through a bearing 41. The rotation of a pulse motor 16 is transmitted to the gear 39 through gears 17 and 18 and a pinion 19 to drive the cam 40. The step parts varying stepwise are provided on the peripheral surface of the cam 40 by as many as the tracks of the disk. The cam 40 abuts on a roll 15 provided to the carriage 11 which is driven, track by track, by 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 accurately detect track positions in a small magnetic disk device using a small diameter magnetic disk. It is something.

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-density recording. 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, which is equipped with a simple mechanism that allows accurate detection of the track position of a magnetic disk.

In order to achieve the above object, the present invention provides a detection piece for detecting the track position on a gear that is rotatably fitted to the output shaft of a motor that rotates a magnetic disk and is rotated by a pulse motor. A structure is adopted in which a cam is provided on the top and is in constant contact with a roller provided on the carriage side.

Hereinafter, 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 section 1, a position detection mechanism 2, a boulder section 3, a disk holding mechanism 4, and a magnetic disk cassette 5 (hereinafter referred to as , magnetic disks are called floppy disks).

The base l 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 cassette) 5 is removably attached to the cassette and plays the role of correctly guiding the cassette.

Further, the disk holding mechanism 4 serves to apply a pressing force to the floppy disk and 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, and its output shaft 8 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, and a carriage 11 is slidably fitted into these guide rails 9 and 10. Coil springs 12 are attached to the guide rails 8 and 1o.
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 that performs tracking in conjunction with a positioning mechanism to be described later is attached to the lower surface on 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 protruding shaft is a gear 1 rotatably supported near the pulse motor 16.
It meshes with 8. The pinion gear 1 is located on the underside of the gear 18.
9 is integrally provided.

Above the motor 7 is the pinion gear 19. motor 7
The printed circuit board 2° is attached while avoiding the output shaft 8 of. This printed circuit board 2o has a through hole 20a at the negative corner, and this through hole 20a is fitted with a pin 21 protruding from the base 6, and the pin 21 is fixed between the top and bottom by an E ring 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 on the side wall or partition wall.

Photodetectors 25 and 28 each consisting of a light receiving element and a light emitting element are attached to the upper and lower parts of the printed circuit board 20.

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 inside the rotor 27, as shown in FIG. 4, permanent magnets 28, 2!
A is fixed at equal angular intervals. These permanent magnets28.
No. 28 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.
1-L6 are provided, and when a current is passed through these coils L1 to L6, a magnetic flux is generated, and in cooperation with the permanent magnets 28 and 29 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 38 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 38.
Optical detectors 37 and 38 are fixed on the top.

The photodetector 37 detects the pattern 36 and detects the rotor 27.
Detects the rotation speed. Further, the photodetector 38 includes a coil L,
-Detect the positional relationship between L6 and permanent magnets 28 and 29.

A detection circuit using these photodetectors and coils L and -L6 is shown in FIG. In Figure 5, LEI) 1
and Tr5 constitute a photodetector 38;
6 constitutes a photodetector 37.

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

Turn on either one between Tr3 and coil L,,L3゜L
5 or L2, L4, and L6, and the magnetic field from the permanent magnets 28 and 29 forms a magnetic circuit passing through the yoke 30, so that repulsion and attraction alternate between the magnetic flux generated by the coil and occurs, and the rotor 27 begins to rotate.

This rotation is detected by said photodetector 37,38.

Now, when the black color of the pattern 35 is detected by the photodetector 38 consisting of LED 1 and Tr5, the output of Tr5 flows to IC:, , IC2 and is input to the base of Trl, and Trl becomes conductive to coil L1. ＋'L 31
Current is supplied to L5. Further, when white is detected, the output of Tr5 turns on IC1, current flows through Tr2, and current flows through coils L2, L4+L'6. At this time, since IC2 is an inverter, the output is O, Trl is turned off, and no current flows. As a result, coils L1, L3. No current flows through L5.

That is, due to the change in information between LED 1 and Tr5, T
rl 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 CIN and ClFF.
Tr3 is used as a digital switch, and Tr3 is used as an analog switch to control the current flowing through the coil and rotate the rotor 27 containing a permanent magnet.

A servo IC is used to rotate the motor 7 at a constant speed,
Using a CR component such as a crystal oscillator as a part of the servo C3, oscillate a reference frequency with accurate pulse time intervals, input this to the servo IC3, and output 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 1 to 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 L1 to 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 3θ, 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/e, which is 34 m5ec. Also, the standard pulse time interval for rotating the motor at a constant speed is 2 m5ec.
The base of the drive transistor 23 is controlled as the interval. Therefore, pattern 36 was divided into 102 equal parts and 2m5e.
It is possible to divide the signal generation of c.

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 widened to 2IIISeC or more. Rather, what is difficult is the precision of dividing the pattern 36, the precision of the signal rise time of the photodetector 37, etc., and if these precisions 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, the Kino-O side is made of a split type, which reduces the mass of the entire permanent magnet and reduces the gap between the magnetic poles. This creates a space between the parts and reduces the weight.

Also, if you adopt this kind of rotor structure.

In order to downsize motors in the future, it is highly conceivable that permanent magnet materials will be made of expensive rare earth materials, so the use of split permanent magnets will lead to resource savings and cost reductions.

Incidentally, a large-diameter gear 38 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, the relative positional relationship between the magnetic head 14 on the carriage 11 and the output shaft 8 of the motor 7 requires high dimensional accuracy.

The reason for this is that if the dimensional accuracy varies, interrecording and playback of the cassette tape becomes impossible.

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 1θ 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, as shown in Fig. 7, the characteristics of a pulse motor are that when one pulse is applied, the axis of the pulse motor 16 is displaced by 18 degrees, but when the 72nd pulse is applied, it is supposed to be displaced by 36 degrees, but the rotor 61 due to inertia and magnetization accuracy
The rotation is over. Furthermore, when the third pulse is applied, the amount of displacement is reduced by 62 degrees from the planned displacement of 54 degrees. Further, the rotation stop position of the pulse motor generally varies slightly, such as when the fourth energization is applied, the pulse motor rotates 72 degrees as planned.

Therefore, if the cam 40 rotated by the pulse motor 1B has a linear relationship between the rotation angle and the amount of displacement as shown in FIG. 8, then a pulse motor with the characteristics shown in FIG. In this case, the stop position of the carriage 11 varies at a rate of ±δ2154″, 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 head 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 is the same as the number of tracks on a floppy disk in tree-killing. 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 Δ and RAD 14 currently correspond 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 indicated by 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 memorizing it using a control circuit that does not have a built-in control circuit. This is the disk 42 that constitutes the detection mechanism section 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 determined, but in this embodiment, the distance traveled per track is 0.125 mm.
, and since the electrical output change of the photodetector is minute,
It requires expensive circuitry and is impractical.

However, in the present invention, the detection piece 42a rotates slowly together with the gear 39, and the amount of movement per track is approximately 2.
．． 5 mm, it became possible to detect the track position, that is, the head position, using the inexpensive photodetector 25.

On the other hand, although the cam 40 is mounted on the gear 39 together with the disk 42, positional deviations may occur due to processing errors or 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 the eccentric pin gauge 101 is D, and the width of the long hole 42c in the radial direction formed in the disk 42 is W, then D=W, and the small hole 39 into which the eccentric pin 101a fits.
A is formed on the gear 39 side facing the elongated hole 42c.

Therefore, by fitting the eccentric pin gauge 101 into the long hole 42c, fitting the eccentric pin 101a into the small hole Ha, 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 a floppy disk are divided into 40 equal parts with a radius of 15 mm to 20 mm, 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.
If the floppy disk is not driven accurately at a pitch of 125 mm, floppy disks recorded with other devices cannot be used.

Furthermore, if the maximum track diameter position of the magnetic head is 20 mm and the minimum track diameter position is 15 mm, it will not be a common specification with other devices. Therefore, the dimensional tolerance of each component between the output shaft 8 and the magnetic head 14 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 the carriage 11 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 15 can be rotated with a radius δ, and the distance between it and the cam 40 is
In other words, the 6WI can reliably finely adjust the distance between the output shaft 8 to which the cam 40 is fixed and the magnetic head 140.
After completing the adjustment, lock the upper end of the screw shaft 45.
) Screw 4B together and fix it in that position. In this way, variations in processing accuracy and mounting accuracy are absorbed and adjusted.

The cam 40 has a plurality of through holes 40e formed around a central hole 40d into which the output shaft 8 is fitted, as shown in FIG. are fitted and fixed by caulking or other methods.

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, and is fixed by fitting this cylinder 49 to the upper end of the output shaft 8 and screwing a screw 50 from the side.

A disk 51 is fitted into this cylinder 49 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 arcuate spring piece 52 is punched out from a part of this disk 51, and a through hole 4 is formed in a part of the upper surface of the free end side of the spring piece 52. a, and the disk 47
He appears above. This bottle 53 is fitted into a through hole formed in the hub of a floppy disk housed in a cassette, which will be described later, and transmits the rotation of the output shaft 8. This disk 51 is fixed to the post 43 together with the cam 40.

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 spring 58 is stretched between the protruding piece 57 and a protruding piece 6b protruding from the base 6, and applies a force to draw the board 54 toward the base 6.

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 left and right. A bent piece 55c bent downward is formed on the lower side of the bent piece 55b.

These bent pieces 54c, 55b, and 55c serve as guides when the cassette 5 is installed.

In addition, each of the side plates 55 has a casing at its lower end.
A guide piece 55d is formed to guide the.

Levers 59 and 60 are attached to the outside of the left and right side plates 55. These levers 59.80 have through holes 513a and Ha formed along the longitudinal direction in the center thereof, and a guide pin 61 fixed to the protruding piece 57 is provided in these through holes.
are fitted respectively. Projecting pieces 59b and Bob protruding downward at the tip of each of the shields 58 and θ0.
A spring 62 is stretched between the lever 59 and the protruding piece 57, and constantly pulls the respective levers 59 and EiO toward the front side.

Notches 59c and 60c are formed in the front edge of each lever 513, 60 along the longitudinal direction, and a guide pin 63 fixed to the side plate 55 is fitted into these notches. .

In addition, the tip portions of the eight-58 and 60 have an L-shaped bent portion 5i3d bent at right angles toward the substrate 54 side, and a flo
d are formed, and these bent portions 59d, fllQd
is a notch 55 formed on the upper surface of the tip of the side plate 55.
e, so that its tip faces the inside of the side plate 55,
Both sides 5a of the tip of the cassette 5 when the cassette 5 is installed
, 5b.

Furthermore, protruding pieces 59e and EIOe are provided on the front edge of each lever 513.80, and these protruding pieces 59e
.

80e 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 projecting pieces 59b and 59e (1) of each lever 59 and 60b.

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

By the way, a projecting piece 64 is provided at the tip of the base plate 54 at approximately the center thereof, and a lever 6B is rotatably supported at the center of the tip via a pin 65. This lever 6B is formed into a substantially "<" shape, and one end thereof has a bent portion 5 formed at the tip of the lever 59.
A pin 67 that is slidably fitted into the elongated hole 59g formed in the hole 9d is provided to protrude downward.

Further, a protrusion 68 protruding from the upper surface of the other end of the lever 66 engages with a pad arm to be described later.

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 69 is formed into a substantially quadrilateral shape, and the leaf spring 69 is inserted into the through hole Ha formed in the center of the leaf spring 69.
8, the boss 71a of the rotor 71 is pressed against the presser ring 72.
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 t39b 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 Hb 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.

Further, spring pieces 7 are attached to both left and right ends of the other end of the leaf spring 68.
13,713 are formed, and serve to hold down the cassette 5 from above.

The plurality of punched grooves formed between the through holes 69a provide elasticity to the portion surrounding the through holes 139a, and are used to elastically maintain contact between the rotating body 71 and the /\b of the floppy disk. belongs to.

The pad arm 70 has a pad 77 on the lower surface of its distal end, 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
A concave portion 70a is formed on the lower surface of the substrate 0 at a position that can correspond to the protrusion 88 of the lever 66 provided on the substrate 54 side. The pad 77 passes through a notch E19d formed on the side edge of the leaf spring 69 and fits into the elongated hole 54b of the substrate 54, and is disposed facing the magnetic head 14, pressing the floppy disk from above.

- The cassette 5 has a structure as shown in exploded view in FIG.

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 disc 47 and the rotating body 71 are inserted is formed at opposing positions in the center of the cassette half.
1a and 82a- are formed, and openings 81b and 82b into which the magnetic head and pads are inserted are formed near these openings. Inside the upper cassette half 81,
A liner 83 formed in a disc shape is fixed at a plurality of locations indicated by reference numeral 83a via an adhesive or the like. This liner 8
3 has a through hole 83b at a position corresponding to the through hole 81a of the cassette/\-fu 81, and has an opening 83c at a position opposite to the opening 81b. Spring pieces 84 and 85 are connected to the opening 8 between the liner 83 and the cassette nof 81.
It is placed with 3c in between. The base ends 84a, 85a of the spring pieces 84, 85 are fixed to the lower surface of the cassette 81, and their free ends press the liner 83 downward on both sides of the opening 83c. These spring pieces 84
．． The role of liner 85 is to press the liner 83 against the magnetic pads that sandwich the floppy disk from above and below on both sides of the floppy disk, thereby maintaining reliable contact between the floppy disk and the magnetic head.

This state is shown in FIG.

Liners 8B and 8El are provided on the lower cassette half 82 side with a through hole 82a in between, and a small hole 82c is formed at a position that does not come into contact with the floppy disk. A pin 2 protruding from the base 6 side is provided in the small hole 82c.
The upper end of 1 is fitted to form a positioning hole when the cassette is installed.

A floppy disk 87 is accommodated between the liner 83 and the lower cassette half 82. 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 20, but also has a protrusion 21b protruding from its upper edge 21a that fits into the small hole 82c of the cassette half 82. Perform positioning. Also, the upper edge 89a of the support column 811.90 that is integrated with or separate from the side wall of the base 6
, 90a are set to be in the same plane as the upper edge 21a of the pin 21, thereby forming a mounting reference plane. pin 21
The pillars 8J90 and 8J90 are arranged to form each vertex of a triangle, and projecting pieces 89b and 90b are provided on the outside of the upper edge 89a, Ha of the pillars 89.90.
b, 90b serve to position the outer edges 5c, 5d of the cassette 5.

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 89 and 90, and also by the protrusions 21b and protrusions. 89b and 90b for accurate positioning.

By the way, an operating lever 81 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 92. A roller 83 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, 80f of the levers 5f3, 60.

This operating lever 91 is given the habit of rotating clockwise in FIG. 1 about a pin 92 due to its own weight.

Next, the operating method and operation of the front disk device according to the present invention constructed as described 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 towards you by the tensile force of. but,
The lower ends of the protrusions 59e and flOe of the levers 59 and 80 are in contact with the guide rail 10, and do not descend and maintain this state even when the tensile force of the spring 58/ is applied.

At this time, the operating lever 81 is rotated to the front side, and the roller 93
are in contact with the front corners of the guide portions 59f and 80f.

In this state, the lever 66 is rotated counterclockwise in FIG. 2 about the pin 65 via the pin 67 due to the movement of the lever 59 toward the front side, and the protrusion 6th is at the 21st position.
As shown in the figure, the pad arm 70 is in contact with the back side of the recess 70a on the lower surface of the pad arm 70, 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 substrate 54, the tips 5a and 5b of the cassette 5 are inserted into the guide portion 59 and 59.
When the levers 59 and 60 come into contact with the bent pieces 59d and Sod on the back side of the lever 59 and the cassette 5 is further pushed in, the levers 59 and 60 move inward against the tensile force of the spring 62. This limit of movement is regulated by the elongated holes 59a and 130a. Before long, as O moves forward, the projecting pieces 58e and 60e begin to separate from the guide rail 10, as shown in FIG.

At the same time, as the lever 59 moves forward, the lever 66 is rotated clockwise in FIG. 2 via the pin 67, and as shown in FIG. Oa
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, fits into the opening 81b of the cassette 5, and the floppy disk 8
Begin contact with 7.

Eventually, when the /<-511, 60 is pushed all the way to the innermost side, the projections 59e and Else of each lever are separated from the guide rail 10, as shown in Figure @19, and the spring 5th The holder portion 3 centered on the substrate 54 is pulled downward by the tensile force.

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 are in contact with each other, and the cassette 5 is set on the reference surface. At the same time, the rear end portions 5c and 5d of the cassette 5 are positioned and mounted in the left-right direction by the projecting pieces 89b and 90b of the support 813.90.

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

If you wish to remove the cassette 5, press the operating lever 81 downwards from the fully installed state shown in FIG. , EiO are pushed up in both directions and pulled back toward the front by the force of the spring 62. Eventually, the protrusion 59e of each lever
The lower end of the JOe is separated from the guide rail 10, and the entire holder part is locked with the front side raised.

At the same time, lever 59. [(By moving O toward the front side, P.
The rad arm 70 is also raised, and the cassette 5 is pushed back to the front side by a predetermined distance. When the cassette 5 is picked up and pulled out, the spring piece 7 of the leaf spring 88 restrains the cassette 5.
Since it is only 5.76, it can be easily withdrawn.

As is clear from the above description, according to the present invention, a detection piece for detecting the track position is provided on a gear rotatably fitted to the output shaft of a motor that rotates a magnetic disk and rotated by a pulse motor. At the same time, a cam is provided that is in constant contact with a roller provided on the carriage side, and a structure is adopted in which the circumferential surface of this cam is a continuous surface of two steps with the same number of s4 tracks as the number of tracks on the magnetic disk. Therefore, there is an excellent effect that the track position can be detected reliably and tracking can be performed accurately without being influenced by the characteristics of the pulse motor.

[Brief explanation of drawings]

The figures are for explaining one embodiment of the present invention; 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;
Fig. 5 is a partially enlarged longitudinal sectional side view of the cassette, Fig. 16 is a perspective view showing the reference plane setting structure for mounting the cassette, and Fig.
Figures 7 to 18 are side views explaining the operation, Figure 20 is a partially longitudinal side view showing the mounting state of the cassette, and Figures 21 and 22 are side views explaining the operation of the rad arm. figure,
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. IO...Guide rail 11.
・Carriage 14... To magnetism ・Rad 15...
・Roller 16...Pulse motor 20...
Printed circuit board 25.26...Photodetector 21...
Pin 27... Rotor 28, 29... Permanent magnet 34... Disc 40... Cam 47... Disk 54... Substrate 59, 6o, 6B.
...shi/ku-68...plate spring 70...pad arm 77...pad 81.82...
・Cassette half 83.8B...Liner 87・
...Floppy disk 88...Hub 89.90
...Strut 91...Operation lever Fig. 20 Fig. 21 Fig. 7゜ Fig. 22 Fig. 23

Claims (1)

[Claims] A magnetic disk drive in which a magnetic disk cassette can be removably mounted via a holder includes a carriage that has a tendency to move in a fixed direction, a roller installed near a magnetic head mounted on this carriage, and a motor. A gear rotatably attached to the output shaft and rotated by a pulse motor, a detection piece for detecting a track position attached to the gear, and a detection piece attached to the gear and having its peripheral surface constantly in contact with the roller. What is claimed is: 1. A magnetic disk device comprising a cam.