JP3048626B2 - Peak level detector of floppy disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention reproduces servo information recorded on a floppy disk by a magnetic head, and determines the amount of displacement of the magnetic head with respect to a target track from the amplitude of the reproduced voltage. The present invention relates to a peak level detecting device of a floppy disk drive having a magnetic head positioning device of a type that detects and controls the position of a magnetic head so that the amount of displacement becomes zero.

[Conventional technology]

The servo information recorded on the floppy disk is reproduced by the magnetic head, the amount of displacement of the magnetic head with respect to the target track is detected from the amplitude of the reproduced voltage, and the position of the magnetic head is controlled so that the displacement is zero. A conventional floppy disk drive peak level detecting device having a magnetic head positioning device of the type that detects a reproduced voltage by a nonlinear element such as a diode as a means for detecting the amplitude of the reproduced voltage, and detects the half-wave by a smoothing circuit. Means of performing rectification or full-wave rectification is used.

[Problems to be solved by the invention]

The above-described peak level detecting device of a floppy disk device accurately detects the amount of displacement of the magnetic head with respect to a target track because ripples occur in the output of the smoothing circuit when the time constant of the smoothing circuit is small. There is a drawback that can not be done. Further, when the time constant of the smoothing circuit is large, there is a disadvantage that the amount of displacement of the magnetic head with respect to the target track cannot be accurately detected due to diagonal clipping distortion generated in the output of the smoothing circuit.

[Means for solving the problem]

A reproducing circuit having a low-pass filter for amplifying a signal from a magnetic head for reading servo information recorded on a floppy disk and removing unnecessary high-frequency components, the peak level detecting device of the floppy disk device of the present invention,
A peak level detector that detects and outputs the peak level of the amplitude of the signal from the reproduction circuit, a servo information detection circuit that receives the output signal of the reproduction circuit, detects the servo information, and outputs the result. A controller for inputting output signals from the peak level detector and the servo information detector and outputting a signal indicating a position shift of the magnetic head with respect to a target track of the floppy disk; and a signal from the controller. And a motor drive circuit for driving a stepping motor for driving the magnetic head according to the present invention, wherein the peak level detector inputs an output signal of the reproduction circuit and changes the phase of the signal. A first and a second phase shift circuit for leading and lagging the phase difference to about 90 °, A comparator for inputting the output signal of the second phase shift circuit and inverting the output at the zero cross point, and a first pulse generator for inputting the output signal of the comparator and outputting a pulse signal of a constant width at the rising point A second pulse generator that inputs an output signal of the comparator and outputs a pulse signal having a constant width at a falling point thereof, and an output signal of the first pulse generator that inputs the output signal of the first pulse generator. A first sample and hold circuit that outputs a negative peak signal by sampling and holding the output of one phase shift circuit, and an output signal of the second pulse generator that inputs the output signal of the second pulse generator. A second sample and hold circuit that outputs a positive peak signal by sampling and holding an output, the first sample and hold circuit, and the second sample hole And a differential amplifier for receiving the output of the circuit and differentially amplifying the input.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

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

In FIG. 1, 1 is a magnetic head for reading data information and servo information recorded on a floppy disk, and 2 is a low-pass which amplifies an output signal from the magnetic head 1 and removes unnecessary high-frequency components. The reproducing circuit 3 having a filter detects the peak level of the amplitude of the voltage of the output signal 102 from the reproducing circuit 3 and outputs the detected peak level to the controller 4.
A peak level detector output as 103, a servo information detecting circuit for inputting an output signal of the reproducing circuit 2 and detecting servo information, and outputting the detected servo information to the controller 4, and a servo information detecting circuit 4 for the peak level detector 3 The respective output signals from the detection circuit 5 are input to detect the amount of displacement of the magnetic head 1 with respect to the target track, and the stepping motor 7 to which the magnetic head 1 is mechanically coupled is driven through the motor drive circuit 6. Is a controller for controlling the position of the magnetic head 1 so that the above-mentioned displacement amount becomes zero.

 FIG. 2 is a waveform chart showing the operation of the embodiment of FIG.

2, reference numeral 11 denotes a position of the magnetic head 1 corresponding to a track on the floppy disk, arrow A denotes an arrow indicating the direction of rotation of the floppy disk, 13 denotes data information recorded on the floppy disk, and 14 denotes information recorded on the floppy disk. Starting point information indicating the starting point of the servo information 15a and 15b, and 15a and 15b are servo information. The reproduction circuit output signal 102 indicates that the data information 13
And the servo circuit 15a and 15b are output signals of the reproduction circuit when passing through, the peak level detector output signal 103,
3 shows an output of the peak level detector 3 which receives and demodulates a reproduction circuit output signal 102. Reference numeral 105 denotes an output signal of a servo information detection circuit that detects and outputs servo information among output signals from the reproduction circuit 2. The controller 4 corrects the position 11 of the magnetic head 1 on the data information 13 so that the voltages of the portions 103a and 103b corresponding to the servo information 15a and 15b in the output signal of the peak level detector become equal. Drive the stepping motor 7 as described above.

FIG. 3 is a block diagram showing details of the peak level detector 3, and FIG. 4 is a waveform diagram showing the operation thereof.

As shown in FIG. 3 and FIG.
102 (output of the 2a reproducing means in FIG. 4) is input in parallel to the first phase shift circuit 31 and the second phase shift circuit 32, and outputs the output signals of the first phase shift circuit 31 and the second phase shift circuit 32. Each input signal is delayed or advanced so that the phase difference is about 90 °. The output signal (signal 232) of the second phase shift circuit 32 is input to the comparator 33, and the zero cross point is detected. The first pulse generator 34 outputs a pulse signal (signal 234) having a fixed width at the rising point of the output signal (signal 233) of the comparator 33, and the second pulse generator 35 outputs the output signal (signal A pulse signal (signal 235) with a fixed width is output at the falling point of 233). The first sample and hold circuit 36 outputs a negative peak signal by sampling and holding the output signal (signal 231) of the first phase shift circuit 31 with the output signal (signal 234) of the first pulse generator 34. The second sample-and-hold circuit 37 outputs the output signal (signal
231) is sampled and held by the output signal (signal 235) of the second pulse generator 35 to output a positive peak signal. The output signal of the first sample and hold circuit 36 (signal 23
6) and the output signal of the second sample and hold circuit 37 (signal 23
7) is input to the differential amplifier 38 and outputs the output signal 103 of the peak level detector 3. As a result, an output signal without ripple diagonal clipping distortion is obtained as an output of the peak level detector, and it is possible to accurately detect the amount of displacement of the magnetic head with respect to the target track.

The operation of the peak level detector 3 will be further described with reference to FIG. From the left of the signal 102, from the left, mountain 1, mountain 2, ...
・ We call it mountain 5, and valley 1, valley 2, ・ ・
・ If it is called valley 4, the amplitude after valley 3 is peak 3
It is smaller than the previous amplitude. A process in which the peak level detector 3 detects such a change in the peak value will be described. The peak value of peaks 1 to 3 is defined as T0,
The peak value of 5 is defined as T1. Also, the absolute value of the peak values of the valleys 1 and 2 is B0, and the absolute value of the peak values of the valleys 3 and 4 is B1.

(1) Before peak 3 When the value of the output of the first phase shift circuit (signal 131) is sampled and held in accordance with the timing of the output pulse (signal 234) of the first pulse generator, the output of the first sample and hold circuit (signal 236) is obtained. can get. At this time, the value of the signal 236 is -B0. Note that the signal 131 is a signal obtained by shifting the phase of the signal 102, and has the same amplitude.

Similarly, the output pulse of the second pulse generator (signal 235)
When the value of the signal 131 is sampled and held according to the timing of (2), the output of the second sample and hold circuit (signal 237)
Is obtained. At this time, the value of the signal 237 is T0.

Therefore, the differential amplifier output of signal 236 and signal 237 (signal 10
3) becomes T0 + B0.

(2) Valley 3 to Peak 4 The value of the signal 236 changes to -B1. On the other hand, the value of signal 237 is
T0 remains unchanged. Therefore, the value of the signal 103 is T0 + B1.

(3) After valley 4 The value of the signal 237 also changes to T1. Therefore, the value of the signal 103 is T1
+ B1.

As described in (1) to (3) above, the peak level detector 3 detects the peak value.

〔The invention's effect〕

As described above, the peak level detection device of the present invention can obtain an output signal having no diagonal clipping distortion of ripples as its output, so that it is possible to accurately detect the amount of displacement of the magnetic head with respect to the target trunk. It has the effect of becoming. Further, there is also a secondary effect that a peak level output signal can be obtained irrespective of a voltage fluctuation of a power supply supplied to a peak level detector of the reproduction circuit and a common mode noise component appearing in an output signal of the reproduction circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation of the embodiment of FIG. 1, and FIG. 3 shows details of a peak level detector of the embodiment of FIG. Block diagram,
FIG. 4 is a waveform chart showing the operation of the peak level detector of FIG. 1 ... magnetic head, 2 ... reproduction circuit, 3 ... peak level detector, 4 ... controller, 5 ... servo information detection circuit,
6 ... Motor drive circuit, 7 ... Stepping motor, 11
... magnetic head, 13 ... data information, 15a / 15b ... servo information, 31 ... first phase shift circuit, 32 ... second phase shift circuit, 33 ... comparator, 34 ... first pulse generator , 35 ... second pulse generator, 36 ... first sample and hold circuit, 37 ... second sample and hold circuit, 38 ... differential amplifier.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Satoshi Yamamoto 3-20-1, Minamiazabu, Minato-ku, Tokyo Japan Motorola Co., Ltd. (56) References JP-A-55-73972 (JP, A) JP-A-53 -89713 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 21/08-21/10

Claims (1)

(57) [Claims] A reproducing circuit having a low-pass filter for amplifying a signal from a magnetic head for reading servo information recorded on a floppy disk and removing unnecessary high-frequency components, and an amplitude of a signal from the reproducing circuit. A peak level detector that detects and outputs a peak level; a servo information detection circuit that receives an output signal of the reproducing circuit, detects the servo information, and outputs a result thereof; the peak level detector and the servo A controller for inputting an output signal from an information detector and outputting a signal indicative of a displacement of the magnetic head with respect to a target track of the floppy disk; and a stepping motor for driving the magnetic head based on a signal from the controller And a motor drive circuit for driving the disk drive. A first and a second phase shift circuit for inputting an output signal of the reproduction circuit and leading and lagging the phase thereof, respectively, so that the phase difference is about 90 °; A comparator which receives an output signal of the phase shift circuit and inverts the output at the zero cross point, and a first pulse generator which receives the output signal of the comparator and outputs a pulse signal having a constant width at its rising point; A second pulse generator that inputs an output signal of the comparator and outputs a pulse signal of a fixed width at a falling point thereof, and an output signal of the first pulse generator that inputs the first pulse generator. A first sample and hold circuit that outputs a negative peak signal by sampling and holding an output of a phase shift circuit, and an output signal of the second pulse generator that inputs the first phase shift circuit A second sample-and-hold circuit that outputs a positive peak signal by sampling and holding the output of the circuit; and inputs and differentially amplifies the outputs of the first and second sample-and-hold circuits. A peak level detecting device for a floppy disk device, comprising a differential amplifier.