JPH0241830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a floppy disk device or a similar magnetic disk device, and more particularly,
The present invention relates to a magnetic disk device with improved contact between a magnetic head and a disk, that is, head load.

Prior Art A general floppy disk device rotates the disk by rotating a motor using a motor-on signal, and the rotational speed can be determined by detecting an index consisting of a through hole provided in the disk. , generates a head load signal (head contact signal) in synchronization with the first index signal after the index signal period becomes less than 150% of the reference period (rotation speed 50% or more), and brings the magnetic head into contact with the disk. It is configured as follows. For this reason, the head contacts the disk with a substantially constant angular positional relationship with the index, resulting in increased wear at specific points on the circumference of the disk.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic disk device that can uniformize disk wear.

Structure of the Invention To achieve the above object, the present invention includes a disk rotation motor for rotating a magnetic disk, a magnetic head disposed opposite to the disk, and an index for detecting the rotation angle position of the disk. an index detector for detecting at a rate of one per rotation, and after the rotational speed of the disk reaches 50% or more of the reference rotational speed during normal recording or reproduction by driving the motor; a head contact permission signal generation circuit that generates a head contact permission signal in synchronization with the index signal generated from the index detector; a clock pulse generation circuit that repeatedly generates a clock pulse having an unspecified time relationship with respect to the start point of driving the motor; and a head contact signal in response to the first clock pulse generated after the start point of generating the head contact permission signal. A circuit that generates
The present invention relates to a magnetic disk device comprising a head contact mechanism for bringing the magnetic head into contact with the disk in a recording or reproducing state in response to the head contact signal.

Effects of the Invention In the present invention, the clock pulse generation circuit generates a clock pulse having a period approximately equal to the period of the index signal at the reference rotation speed.
Furthermore, this clock pulse has an unspecified (random) time relationship with respect to the motor drive start point, that is, the index signal. Therefore, at an unspecified point in the period from the time when the head contact permission signal synchronized with the index signal is generated until the time corresponding to the period of the index signal at the reference rotation speed has elapsed (the period during which the disk rotates half a revolution or more) The head comes into contact with the disk. Therefore, the contact position of the head with the disk varies within the range of 0 degrees to at least 180 degrees (up to 360 degrees), reducing wear on specific positions of the disk and extending the life of the disk. .

Embodiment Next, a magnetic disk device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. In FIG. 1 showing a magnetic disk device, 1 is a flexible magnetic disk, 2 is a disk rotation motor, 3 is a motor control drive circuit, 4 is a first magnetic head, and 5
1 is a second magnetic head, 6 is a carriage, 7 is a head positioning mechanism including a stepping motor, 8 is a head support arm, 9 is a head contact mechanism (head load mechanism) consisting of a plunger solenoid, 1
0 is the index detector. The index detector 10 has a light emitting element 11 placed on one side of the disk 1 and a light receiving element 12 placed on the other side.
It optically detects an index 13 consisting of a through hole provided in the disk 1 and sends out an index signal.

Reference numeral 14 denotes a head contact permission signal generation circuit, which is composed of a retrigger monostable multivibrator 15 triggered by an index signal, and a D-type flip-flop 16 whose Q output is used as a D input. The output line of the index detector 10 is connected to the trigger terminal T of the retrigger monostable multivibrator 15 and the clock terminal of the D-type flip-flop 16.
D-type flip-flop 1 for CK and ready signal formation
The Q output terminal of the monostable multivibrator 15 is connected to the D input terminal of the D-type flip-flop 16, and is connected to the reset terminal R of the D-type flip-flops 16 and 17, respectively. The Q output terminal of the D-type flip-flop 16 is connected to the D input terminal of the D-type flip-flop 17 in the next stage, and the
It is connected to the D input terminal of the type flip-flop 18 and the reset terminal R.

19 is a head contact signal generation circuit, 5Hz
AND
It consists of a gate 21. Note that the pulse generation circuit 2
The output line of 0 is connected to the clock terminal CK of the D-type flip-flop 18, the Q output terminal of the D-type flip-flop 18 is connected to one input terminal of an AND gate 21, and the other input terminal of the AND gate 21 supplies the motor-on signal. It is connected to line 22.

FIG. 2 shows a flexible magnetic disk cartridge 23 containing the magnetic disk 1. As shown in FIG.
The magnetic disk 1 is housed in a jacket 24, and the jacket 24 has an opening 25 for exposing the center of the disk 1 and an opening 2 for inserting the magnetic head.
6. Opening 2 for exposing index 13
7th grade is provided. In a magnetic disk device, the magnetic disk 1 is mounted together with a jacket 24 and rotated within the jacket 24.

Next, the operation of this disk device will be explained with reference to FIG. 3, which shows the states at points A to G in FIG. 1. Attach disk 1 to the disk rotation mechanism,
When the motor on signal _t1 shown in FIG. 3A is supplied from a controller (not shown), the motor 2
is driven, and the rotation of the disk 1 starts. When the disk 1 starts rotating in this manner, the index 13 is detected by the index detector 10, and the index signal shown in FIG. 3B is generated at a rate of one per rotation of the disk 1. This serves as a trigger input for a retriggerable monostable multivibrator 15 whose output pulse width is set to 300 ms. When the monostable multivibrator 15 is triggered at the leading edge of the index signal at time _t2 , as shown in FIG. 3C, this Q output switches to a high level. If the cycle (interval) of the index signals is 300 ms or more, that is, if the rotational speed of disk 1 is less than 50% of the reference speed, the next index signal is generated as shown in FIG. _3C. Before the point in time, the Q output of the monostable multivibrator 15 returns to a low level.
However, when the period of the index signal becomes less than 300ms, as shown in the period _t3 to _t4 , the monostable multivibrator 15 becomes retriggered, and this Q
The output is held at a high level. D-type flip-flop 16 holds the output of monostable multivibrator 15 shown in FIG. 3C in synchronization with the leading edge of the index signal. At time _t3 , the rise of the monostable multivibrator 15 lags behind the leading edge of the index signal, so the D-type flip-flop 16
does not hold high level data and is kept in a low level state, but at the leading edge of the next index signal that occurs at time t ₃ , the high level data shown in Figure 3C is read and the data is changed to Figure 3D. As shown, the Q output changes to a high level. In a conventional floppy disk device, a D-type flip-flop 16 occurs at time _t4 .
The output of the PRE READY signal was used as a head load signal, and at this time point _t4 , the head 5 was brought into contact with the disk 1, and the disk 1 was held between the pair of heads 4 and 5. Therefore, the head load has a constant time relationship with the index signal, and there is a risk that the wear of the same portion of the disk 1 will increase. Therefore, the device of this embodiment has a third
The head load mechanism is configured so that it does not operate at the rising edge of the signal shown in Figure D. The output of the D-type flip-flop 16 is the D-type flip-flop of the head contact signal generation circuit 19.
The signal is supplied to the D input terminal of the D-type flip-flop 18 and held in the D-type flip-flop 18 in synchronization with the leading edge of a clock pulse having a period of 200 ms shown in FIG.
That is, at the leading edge time _t5 of the first clock pulse generated after time _t4 , the high level signal shown in FIG. 3D is held in the D flip-flop 18, and this Q
The output switches to a high level as shown in Figure 3G.
Since the clock pulse shown in FIG. 3F is generated independently of the motor-on signal shown in FIG. 3A, the period from time t ₄ to time t ₅ is an unspecified period and varies randomly. At time _t5 , the motor-on signal has already been generated as shown in Figure 3A, so
The Q output of the D-type flip-flop 18 is applied to the head contact mechanism 9 through the AND gate 21, and the plunger solenoid constituting the head contact mechanism is actuated to release the blocking of the head support arm 8. That is, the head support arm 8 has a spring property and has a biasing force in the direction (counterclockwise) so that the head support arm 5 comes into contact with the disk 1, but when not recording or reproducing,
The heads are maintained in the separated position against the biasing force of the arm 8. Then, by actuation of the plunger solenoid based on the generation of the head contact signal (head load signal) shown in FIG. come into contact with. At this time, when the upper head 5 presses the flexible disk 1, the disk 1 also comes into contact with the lower head 4.

Since the clock pulse shown in FIG. 3F is generated at the same period as the index signal during normal rotation, it is always generated between time _t4 , which is the pre-ready state, and time _t6 , when the next index signal is generated. When the index signal occurs at time t ₆ ,
At this leading edge, a D-type flip-flop 17 is formed as shown in FIG.
As shown in FIG. 3E,
Outputs a high-level ready signal at _t6 . Note that this ready signal is a ready signal indicating that the disk 1 has reached a certain number of revolutions and can begin recording or reproduction. Therefore, when the ready signal shown in FIG. 3E is generated, the heads 4 and 5 start recording and reproducing.

As is clear from the above, this embodiment has the following advantages.

(a) A head contact signal (head load signal) having an unspecified time relationship to the index signal.
As a result, the head load position in the circumferential direction of the disk 1 becomes unspecified, and wear of the disk 1 can be made uniform. This lengthens the life of the disk 1.

(b) Since the period of the clock pulse sent from the pulse generation circuit 20 was set to 200 ms, which is the same as the period of the index signal at the standard rotation speed, the first signal indicating that the period of the index signal has become less than the predetermined time (300 ms) There is no problem even if the ready signal is generated at time _t6 , when the next index signal is generated, with reference to the index signal generation time _t4 . In other words, the magnetic heads 4 and 5 can be brought into contact with the disk 1 before the ready signal is generated at time _t6 .

Modifications The present invention is not limited to the embodiments described above, and the following modifications are possible.

(A) Single-sided floppy disk device, i.e.
It is also applicable to a device in which the lower head 4 is brought into contact with the disk 1 by using the upper head 5 in the figure as a head load pad and pressing the pad against the disk 1.

(B) The jacket 24 has rigidity,
It is also applicable to devices using microfloppy disk cartridges.

(C) In the embodiment, the head contact permission signal (pre-ready signal) is generated based only on the index signal, but an independent speed detector is provided to detect the rotational speed of the disk 1 or motor 2, and this detects the rotation speed at a predetermined speed. The head contact permission signal may be generated when the index signal is generated. Further, the time for the disk 1 to reach a predetermined speed is measured in advance, and a monostable multivibrator having a pulse width of this time is triggered at the rising edge of the motor-on signal shown in FIG. 3A to generate a pulse, and this pulse period ends. The head contact permission signal may be generated in synchronization with the first index signal.

(D) Instead of configuring the head contact signal generation circuit 19 with a pulse generation circuit 20 and a D-type flip-flop 18, the output pulse width may be, for example, 0 to 200ms.
A pulse generating circuit such as a monostable multivibrator that changes _randomly within the range of It may also be the rising edge of the head load signal. Note that a random pulse width can be obtained by randomly changing the time constant of a monostable multivibrator.

(E) Various signals may be low level signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a plan view showing a disk cartridge used in the device shown in FIG. 1, and FIG. 3 is a state of each part shown in FIG. 1. FIG. 1... Disc, 2... Disk rotation motor,
4, 5...Magnetic head, 7...Head positioning mechanism, 9...Head contact mechanism (head load mechanism),
10... Index detector, 13... Index, 14... Head contact permission signal generation circuit, 1
6, 17, 18...D type flip-flop, 19
. . . Head contact signal generation circuit, 20 . . . Pulse generation circuit.

Claims (1)

[Scope of Claims] 1. A disk rotation motor for rotating a magnetic disk, a magnetic head disposed opposite to the disk, and an index for detecting the rotation angle position of the disk at a rate of one per rotation of the disk. an index detector for detecting an index, which is generated from the index detector after the rotational speed of the disk reaches 50% or more of a reference rotational speed during normal recording or playback by driving the motor; a head contact permission signal generation circuit that generates a head contact permission signal in synchronization with an index signal; a clock pulse generation circuit that repeatedly generates clock pulses having an unspecified time relationship; a circuit that generates a head contact signal in response to the first clock pulse generated after the start of generation of the head contact enable signal; A magnetic disk device comprising: a head contact mechanism for bringing the magnetic head into contact with the disk in a recording or reproducing state in response to a head contact signal.