JPH0439122B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a phase compensation method and apparatus for a magnetic recording/reproducing device.

[Technical Background of the Invention] Magnetic recording and reproducing devices generally have extremely complex circuit systems because they record and reproduce input signals via a magnetic recording medium (magnetic tape, magnetic disk, etc.). In such a circuit system, even if the frequency characteristics (characteristics that express the relationship between the levels of the input signal and the reproduced output signal as a function of frequency) are flat, for example, the input signal and the reproduced output signal can be measured using an oscilloscope. The waveforms are not necessarily the same when observed.

This is because the delay time of the input signal passing through the circuit system and the reproduced output signal differs depending on the frequency.

Conventionally, as a means for shaping the waveform of a reproduced output signal, there is an example of performing phase compensation of an input signal before recording the input signal on a magnetic recording medium, as disclosed in Japanese Patent Laid-Open No. 58-29112.

This phase compensation method will be explained with reference to FIGS. 1 and 2.

A phase compensation circuit 1 having a variable resistor Rv is connected between the input terminal In and the recording amplifier 3 of the magnetic recording/reproducing device 2, and the phase of the input signal passing through the phase compensation circuit 1 is adjusted by changing the variable resistor Rv. Compensate for.

The phase compensation circuit 1 is also called an all-pass filter, and although its frequency characteristics are constant over a wide band, its phase characteristics vary depending on the frequency.

The input signal that has passed through the phase compensation circuit 1 is recorded as a magnetic signal on a magnetic recording medium 5 via a recording amplifier 3 and a magnetic head 4.

This magnetic signal is regenerated into an electric signal by the reproducing head 6 and further sent to the output terminal OUT via the reproducing amplifier 7 as a reproduced output signal.

Input the square wave input signal A shown in Figure 2a to the input terminal.
When inputting to In, from output terminal OUT to Fig. 2b,
Reproduction output signals B, C, and D corresponding to the amounts of compensation by the phase compensation circuit 1 as shown in c and d, respectively, are output.

At this time, the waveform of the reproduced output signal D is most similar to the input signal A, and can be said to be in an optimal compensation state.

On the other hand, when the reproduced output signals B and C are output, the amount of compensation is changed by operating the variable resistor Rv,
Adjustments are made so that the waveform resembles the reproduced output signal D.

[Problems with the background art] The conventional phase compensation method described above requires manual adjustment of the variable resistor Rv while comparing the input signal and the reproduced output signal using an oscilloscope, etc. There are individual differences due to subjective factors, and a lot of time is required for phase compensation.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides a phase compensation method for a magnetic recording and reproducing device that can easily perform phase compensation of the magnetic recording and reproducing device, and a method that automatically determines the optimum amount of compensation. It is an object of the present invention to provide a phase compensation device that can be set.

[Summary of the Invention] The outline of the method of the present invention for achieving the above object is to record a square wave signal on a magnetic recording medium while compensating its phase, and to record the lowest value of the peak level of the reproduced output signal from the magnetic recording medium. This method is characterized in that the input signal is subjected to phase compensation based on the amount of phase compensation that is detected and corresponds to the lowest value.

The apparatus of the present invention for achieving the above object includes a square wave signal generating circuit that generates a square wave signal, a square wave signal generating circuit that is configured to be able to vary the amount of compensation, and a magnetic field that compensates the phase of the square wave signal while a phase compensation circuit that sends the signal to the recording/reproducing device; a peak detection circuit that detects the peak level of the reproduction output signal from the magnetic recording/reproducing device; and a phase compensation circuit based on the lowest value of the peak level sent from the peak detection circuit. The invention is characterized by comprising a control means for controlling the amount of compensation.

[Embodiments of the Invention] The principles and embodiments of the present invention will be described in detail below.

First, the principle of the present invention is described above in Figures 2a, b,
This will be explained with reference to each waveform diagram shown in c and d and a graph showing the relationship between the amount of compensation by the phase compensation circuit 1 and the peak level of the reproduced output signal in FIG.

When phase compensation is applied to the input signal A and the compensation amounts S1 to S9 are gradually changed as shown in Fig. 3, the waveforms of the reproduced output signals B, C, and D are as shown in Fig. 2 b, c, and d. Changes as shown in .

At this time, if the compensation amount is changed while detecting the peak levels P _B , P _C , and _PD of the reproduced output signals B, C, and D, respectively, a graph as shown in FIG. 3 is obtained.

In the figure, the compensation amount S2 corresponds to the peak level P _B of the reproduced output signal B, the compensation amount S8 corresponds to the peak level P _C of the reproduced output signal C, and the compensation amount S5 corresponds to the peak level P _D of the reproduced output signal D. do.

Since the waveform of the reproduced output signal D is most similar to the waveform of the input signal A, the compensation amount S5 is set as the optimum compensation amount.

In this way, the lowest peak level P _D of the peak levels P _B , P C , and P _D of each reproduction output signal B, _C , and D is determined.
By determining the compensation amount S5 corresponding to , and performing the phase compensation of the input signal A using this as the optimum compensation amount, a reproduced output signal that is the same as or similar to the input signal A can be automatically obtained.

Next, an embodiment of a phase compensation method and apparatus for realizing the above principle will be described.

FIG. 4 is a block diagram showing the configuration of the phase compensator. Components having the same functions as those shown in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

The device shown in the figure includes a square wave signal generation circuit 10 that outputs a square wave input signal A, and
a switch section 11 for switching between the input signal and the normal input signal from the input terminal IN; and a phase compensation circuit 12 connected between the switch section 11 and the recording amplifier 3.
, a peak detection circuit 13 that is connected to the output terminal OUT of the magnetic recording/reproduction device 2 and detects the peak level of the reproduction output signal, and an A/D converter 14 that converts the output of the peak detection circuit 13 into an analog-to-digital format. The control means 15 controls the amount of compensation by the phase compensation circuit 12 based on the output of the A/D converter 14.

Next, a phase compensation method using the apparatus having the above configuration will be explained.

From the square wave signal generation circuit 10 to the switch section 11,
A square wave input signal A is input to the recording head 4 via the phase compensation circuit 12 and the recording amplifier 3, and this input signal A is recorded as a magnetic signal on the magnetic recording medium 5. A peak detection circuit 13 detects the peak level of the reproduced output signal outputted from the output signal.

The output of the peak detection circuit 13 is converted into a digital signal by the A/D converter 14, and then input to the control means 15.

The control means 15 sends a control signal to the phase compensation circuit 12 based on this digital signal,
As a result, the compensation amount S5 corresponding to the lowest value of the peak level is set in the phase compensation circuit 12 according to the above-described principle, and the input signal A is automatically subjected to optimal phase compensation.

In this way, the waveforms of the input signal and the reproduction output signal of the magnetic recording/reproduction device 2 can be made the same.

Next, a specific example of the configuration of the above-mentioned apparatus will be explained with reference to FIG. Components having the same functions as those shown in FIG. 4 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

The phase compensation circuit 12 in the device shown in the figure is as follows:
Any number of resistors R ₁ .R ₂ to set the amount of compensation,
A group of resistors Rn with... and each resistor R ₁ ,
A variable resistance section 20 consisting of a switch group SWn including switches SW ₁ , SW ₂ , ... corresponding to R ₂ , ...
It is configured with

The peak detection circuit 13 includes a rectification circuit 21 that rectifies the reproduction output signal from the reproduction amplifier 7, and a peak hold circuit 22 that detects the peak level of the output of the rectification circuit 21 and temporarily holds the peak. There is.

This peak hold circuit 22 has an input resistance Rx,
Operational amplifier 23 for impedance conversion, diode D, operational image width unit 24 for peak hold, capacitor C, feedback resistor R _Y , and the capacitor C
The output is reset by a control signal from the control means 15.

The control means 15 controls the switch group SWn of the phase compensation circuit 12 based on the output of the A/D converter 14.
The input/output control circuit 26 controls switching and sends control signals to the reset FET 25 and the A/D converter 14, and a CPU 27 controls the input/output control circuit 26.

Next, a phase compensation method using the apparatus having the above configuration will be explained.

The reproduction output signal output from the reproduction amplifier 7 is
After being rectified by the rectifier circuit 21, the signal is input to the peak detection circuit 3. An output signal corresponding to the peak level of the reproduced output signal appears on the output side of the operational amplifier 24, and this output signal is held by the capacitor C. In this way, the peak level of the reproduced output signal is detected.

This output signal is then sent to the A/D converter 14.
The signal is converted into a digital signal and input to the input/output control circuit 26.

When the CPU 27 receives the digital signal corresponding to the peak level from the input/output control circuit 26, it stores this information and instructs the input/output control circuit 26 to change the characteristics of the phase compensation circuit 12 to the next step. At the same time as sending a control signal, a control signal is sent to operate the reset FET 25 to detect the next peak level value. and
CPU25 is the phase compensation circuit 1 with the lowest peak level after repeating this series of operations.
Characteristic No. 2 is assumed to be the optimum phase compensation characteristic.

As a result, one of the resistors R ₁ , R ₂ , . . . that provides the optimum compensation amount S5 for the input signal is selected, and phase compensation for the input signal A is automatically performed.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made within the scope of the invention.

[Effects of the Invention] According to the method of the present invention described in detail above, optimal phase compensation for the input signal of a magnetic recording/reproducing device can be easily performed without using an oscilloscope or the like as in the conventional method.

Further, according to the present invention, it is possible to provide a phase compensation device that can automatically set the optimum compensation amount and make input and output signals the same.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional phase compensation circuit, Fig. 2 a is a waveform diagram showing an input signal of a magnetic recording/reproducing device, and Figs. 2 b, c, and d are waveforms showing the same reproduction output signal, respectively. 3 is a graph showing the relationship between the compensation amount of phase compensation and the peak level of the reproduced output signal, FIG. 4 is a block diagram showing an embodiment of the phase compensation device of the present invention, and FIG. FIG. 2 is a block diagram showing a specific example of the configuration of the device shown in FIG. 2... Magnetic recording and reproducing device, 5... Magnetic recording medium, 10... Square wave signal generation circuit, 12... Phase compensation circuit, 13... Peak detection circuit, 15... Control means.

Claims (1)

[Claims] 1. A square wave signal is recorded on a magnetic recording medium while being phase-compensated, the lowest value of the peak level of the reproduced output signal from the magnetic recording medium is detected, and the phase compensation corresponding to this lowest value is determined. A phase compensation method for a magnetic recording/reproducing device, characterized in that phase compensation is applied to an input signal by a compensation amount. 2. A square wave signal generation circuit that generates a square wave signal, a phase compensation circuit that is configured so that the amount of compensation can be varied and that sends out the square wave signal to a magnetic recording and reproducing device while performing phase compensation on the square wave signal, and a magnetic recording and reproducing device. A peak detection circuit that detects the peak level of a reproduced output signal from the peak detection circuit, and a control means that controls the compensation amount of the phase compensation circuit based on the lowest value of the peak level sent out from the peak detection circuit. A phase compensation device for a magnetic recording/reproducing device.