JP2821292B2 - Track 0 signal circuit of flexible disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track 0 signal generating circuit for a flexible disk drive, and more particularly to a circuit for preventing a malfunction due to overshoot during a seek operation.

[0002]

2. Description of the Related Art A track 0 signal circuit of a conventional flexible disk drive has a configuration as shown in FIG.
In FIG. 2, the track 0 sensor 1 is at the H level on the outer circumference side of the track on which the magnetic head is magnetically recorded, that is, on the outer circumference than the normal track 2.

[0003] Stepper excitation circuit 2 varies for each rise of the step signal, repeat the same output for each track 4, as shown in FIG. 14.

The logic circuit 3 has an output specified by a truth table shown in FIG. 7 , and only when the stepper excitation circuit 2 indicates track 0 and the output of the track 0 sensor 1 is at the H level, Outputs a 0 signal.

[0005] Next, the operation will be described with reference to the time chart of FIG. 8. First, it is assumed that the magnetic head is on track 5.

Here, each time a step signal is input, the magnetic head moves one track at a time. When the magnetic head moves over the track 2, the track 0 sensor 1 outputs an H level.

Further, when a step signal is input and the magnetic head comes over track 0, the stepper excitation circuit 2 becomes the excitation phase of track 0, and the logic circuit 3 outputs the track 0 signal.

[0008]

The track 0 signal circuit of the conventional flexible disk drive has the following problems.

As shown in FIG. 8 , when the magnetic head moves from the track 5 to the track 4, the magnetic head overshoots due to the vibration caused by the movement between the tracks, and the stepper excitation circuit 2 excites the track 4. Regardless, the output of the track 0 sensor 1 sometimes becomes the H level instantaneously.

Since the output of the stepper excitation circuit 2 of the track 4 is the same as that of the track 0, the logic circuit 3 outputs an instantaneous track 0 signal.

As a result, even when the magnetic head is on the track 4, the host device may erroneously judge that the track is the track 0.

An object of the present invention is to provide a track 0 signal circuit of a flexible disk drive which prevents a track 0 signal from being output in areas other than track 0.

[0013]

In order to achieve the above object, a track 0 signal circuit of a flexible disk drive according to the present invention comprises a track 0 sensor and a time domain buffer.
A filter having a filter, a stepper excitation circuit, and a logic circuit.
The track 0 signal circuit of the flexible disk drive
The track 0 sensor detects that the magnetic head is on an outer track , and the time domain
In filters, which is connected to the track 0 sensor, which does not output pulses shorter than a predetermined time, the
Stepper excitation circuit, the step signal sent from the host
And excitation phase of the stepping motor for moving the magnetic head position at the leading edge of the one of changing one track, before
The logic circuit includes a track 0 signal based on an output of the stepper excitation circuit and an output of the time domain filter.
Is output . Also according to the present invention flexible
The track 0 signal circuit of the disk drive is
, A timer, a storage element, a stepper excitation circuit,
Track of flexible disk drive having logical circuit
0 signal circuit, wherein the track 0 sensor is a magnetic head.
Is located on the outer track.
The timer has a fixed width from the rising of the step signal.
And outputting a pulse .
From the track 0 sensor based on the pulse from the imager
And the stepper excitation circuit.
Moves the position of the magnetic head at the rise of the step signal.
Excitation phase of the stepping motor to be changed by one track
It is intended to, the logic circuit, the stepper excitation times
Track 0 signal based on the output of the path and the output of the storage element.
Signal.

[0014]

According to the present invention, a thin pulse transiently output from the track 0 sensor is removed by a time domain filter.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the figure, 1 is a track 0 sensor, 2 is a stepper excitation circuit, and 3 is a logic circuit. Reference numeral 11 denotes a time domain filter for canceling a pulse shorter than a predetermined time.

The time domain filter 11 has a configuration as shown in FIG. 41 an edge differentiation circuit for outputting a narrow pulse every rising edge of the input pulse, both edges of falling, has a structure shown in FIG. Operation is figure
The input is delayed by the time constant circuit 61 as shown in FIG.
When the two inputs are different, the exclusive OR circuit 62 outputs an H level.

Reference numeral 42 denotes a monostable multivibrator that outputs a pulse for a predetermined time for each input pulse, and reference numeral 43 denotes a D-type flip-flop that holds the value of the D input when the CK input rises.

The time domain filter 11 performs the operation shown in FIG. 9. When a pulse is input as an output of the track 0 sensor, the edge differentiating circuit 41 operates, the monostable multivibrator 42 outputs a pulse for a fixed time, and the D-type flip-flop 43 holds the track 0 sensor output at the trailing edge of the pulse.

Here, when the output of the track 0 sensor 1 is shorter than the output pulse of the monostable multivibrator 42,
This pulse is not output.

Further, the time domain filter 11 can also be configured as in FIG. 5 as a separate circuit. 41 is an edge differentiating circuit, 51 is a counter and reset input (R terminal)
, The pulse of the clock input (CK terminal) is counted, and when it reaches the specified number, it is output from the carry output (CY terminal). Thereafter, the counter enters a free-run state.

Reference numeral 52 denotes an oscillator, which continuously outputs pulses having a constant period. Reference numeral 53 denotes a set / reset flip-flop. When a set input (S terminal) is input, the output Q goes high, and when a reset input (R terminal) is input, the output Q is output.
Becomes L level. 43 is a D type flip-flop.

[0024] The operation is as shown in FIG. 10. When the track 0 sensor output is input, the edge differentiating circuit 41 operates,
The counter 51 is reset. At the same time, the set / reset flip-flop 53 is set.

When the counter 51 counts the output of the oscillator 52 by a specified number, it outputs a carry and resets the set / reset flip-flop 53. Here, the D-type flip-flop 43 latches the track 0 sensor output. Here, the track 0 sensor output that is later than the time until the carry output of the counter 51 is output is not output.

[0026] explaining the operation according to the time chart of the subsequent Figure 12. First, it is assumed that the magnetic head is on the track 5. Here, when the magnetic head moves to track 4 by one track, the magnetic head overshoots and a thin pulse is output as an output of the track 0 sensor 1.

This pulse is applied to the time domain filter 11
And is not output as a track 0 signal.

Thereafter, when the magnetic head moves and arrives on track 2, the track 0 sensor 1 becomes a stable H level. When the magnetic head further moves and reaches track 0, the stepper excitation circuit 2 turns on the track 0 excitation phase. And the logic circuit 3 outputs the track 0 signal.

[0029]

In FIG. 3, reference numeral 21 denotes a first logic circuit.
It has the truth table of FIG. Reference numeral 22 denotes a track counter on which track the magnetic head is located. Reference numeral 23 denotes a decoder which has a truth table shown in FIG.
The H level is output in the following cases.

[0031]

[0032]

[0033]

(Embodiment 2 ) FIG. 3 is a block diagram showing Embodiment 2 of the present invention.

In FIG. 3 , reference numeral 31 denotes a storage element which holds data when a trigger is input. Here, a D-type flip-flop is used.

Reference numeral 32 denotes a timer which outputs a pulse for a predetermined time from the rising of the step signal.

[0037] be described with reference to FIG. 13 operation. First, it is assumed that the magnetic head is on the track 5. Here, when a step pulse is sent from the host, the one-track magnetic head moves, and the track 0 sensor 1
Outputs a thin pulse.

The timer 32 outputs an L level pulse for a fixed time. Here, the time for outputting the pulse is set longer than the overshoot. Since the storage element 31 stores data at the trailing edge of this pulse, the output of the storage element remains at the L level.

When the magnetic head is further moved, the output of the track 0 sensor 1 on the track 2 becomes a stable H level, and the output of the storage element 31 also becomes an H level. When the magnetic head comes to track 0, a track 0 signal is output.

[0040]

As described above, the present invention prevents the output of the track 0 signal other than the track 0, so that erroneous information is not transmitted to a host device using the track 0 signal. Have.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a time domain filter of the present invention.

FIG. 5 is a block diagram showing another time domain filter according to the present invention.

FIG. 6 is a circuit diagram showing an edge differentiating circuit according to the present invention.

FIG. 7 is a diagram showing truth values of a logic circuit;

FIG. 8 is a time chart in the case of the related art.

FIG. 9 is a time chart showing the operation of the time domain filter according to the present invention.

FIG. 10 is a time chart of another embodiment of the time domain filter in the present invention.

FIG. 11 is a time chart of the edge differentiating circuit according to the present invention.

FIG. 12 is a time chart illustrating the operation of the first embodiment.

FIG. 13 is a time chart illustrating the operation of the third embodiment.

FIG. 14 is a diagram showing a truth value of the stepper excitation circuit.

[Explanation of symbols]

 Reference Signs List 1 track 0 sensor 2 stepper excitation circuit 3 second logic circuit 11 time domain filter 21 first logic circuit 22 track counter 23 decoder 31 storage element 32 timer 41 edge differentiation circuit 42 monostable multivibrator 43 D-type flip-flop 51 counter 52 Oscillator 53 Set / Reset / Flip-flop 61 Time constant circuit 62 Exclusive OR circuit

Claims (2)

(57) [Claims] A track 0 sensor and a time domain
A filter having a filter, a stepper excitation circuit, and a logic circuit.
The track 0 signal circuit of the flexible disk drive
Te, the track 0 sensor is configured to detect that the magnetic head is on the circumferential track, the time domain filter, connected to said track 0 sensor, also not output pulses shorter than a predetermined time
And than, the stepper exciting circuit causes the excitation phase of the stepping motor for moving the magnetic head position at the rising step <br/> No. signal sent from the host to change one track Monodea
The logic circuit outputs a track 0 signal based on the output of the stepper excitation circuit and the output of the time domain filter.
2. A track 0 signal circuit of a flexible disk device characterized by outputting a signal. 2. A truck 0 sensor, a timer, and a memory element.
Flexible circuit including a stepper, a stepper excitation circuit, and a logic circuit.
A track 0 signal circuit of a shivable disk device, wherein the track 0 sensor includes a magnetic head on an outer track.
The timer detects a pulse having a certain width from the rise of the step signal.
Output from the timer , and the storage element outputs a previous value based on a pulse from the timer.
It stores data from the track 0 sensor.
The stepper excitation circuit turns on the magnetic field at the rise of the step signal.
Excitation phase of stepping motor to move head position
Is changed by one track, and the logic circuit outputs the output of the stepper excitation circuit and the
Outputs track 0 signal based on output of storage element
Track 0 signal circuit of the flexible disk device, characterized in that it.