JPH02218005A - Waveform equalization device - Google Patents

Abstract

PURPOSE:To equalize a reproducing signal from a medium to a specified waveform by inverting the reproducing signal in a time base direction and adding an inversion signal to a reproducing original signal. CONSTITUTION:An input signal is divided to the specified width of a certain time by a signal time divider 8 and inverted in terms of every time base by a signal time base inverter 9. Then, the input signal is delayed by a delay line 10. Inversion output and delay output are added 11. A division signal is A/D converted 12 in the converter 9 and stored in a memory 13, and the signal is read out by a control circuit 14 in inverse order.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a waveform equalization device for equalizing the waveform of a signal reproduced from a perpendicular magnetic recording medium in a magnetic recording and reproducing apparatus.

In a conventional magnetic recording/reproducing device, a signal reproduced by a ring-shaped magnetic head from a magnetic recording medium oriented in the in-plane direction is generally a row 1 . 〉A linearly symmetrical waveform in the shape of a square (hereinafter referred to as an in-plane waveform). On the other hand, a signal reproduced by a ring-shaped magnetic head from an ideal perpendicular magnetic recording medium has a point-symmetrical waveform (hereinafter referred to as a perpendicular waveform) as shown in FIG. 3(b). However, when recording is performed on a perpendicular magnetic recording medium with a ring-shaped magnetic head, the signal reproduced by the ring-shaped magnetic head has an asymmetrical waveform in which an in-plane waveform and a perpendicular waveform are superimposed ( (hereinafter referred to as superimposed waveform).

Possible methods for data discrimination processing of this superimposed waveform signal include peak point detection by differentiation and maximum slope point detection by double differentiation, but the former causes a large peak shift due to waveform interference, and the latter uses double differentiation to detect the maximum slope point. This had the disadvantage of causing a decrease in the /N ratio.

Therefore, as described in the following document 1, there is a method of converting an in-plane/vertical superimposed waveform into an in-plane waveform by utilizing the Hilbert transform relationship between an in-plane waveform and a vertical waveform. Ta. In particular, the method presented in Document 2 below is said to be effective.

Literature 1... Tsui, Hi, Misbukunin (V, B
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En3ineerin3) V29-30. ppH4
-120゜Reference 2: Published Patent Publication 1986-231
404.degree. FIG. 5 is a block diagram showing the configuration of a conventional waveform equalization device using Hilbert transform. A signal input to the input terminal 1 is output to each end of the tapped differential delay line 2. A reflective terminating resistor 3 is connected to the tapped differential delay line 2 . The reflective terminating resistor 3 is selected depending on the magnetization component ratio of the perpendicular magnetic recording medium. Tapped differential delay line 3
The weighted outputs of each tap are added by an adder 4. On the other hand, the terminal output of the tapped differential delay line 3 is amplified by the amplifier 5. The weighted output of the amplifier 5 is added to and subtracted from the output of the adder 4 by an adder/subtractor 6, and then outputted to an output terminal 7. This output is obtained by adding or subtracting the Hilbert-transformed waveform of the human input signal and the waveform obtained by delaying the input signal by a fixed time at a ratio determined by the resistor 11α of the reflective terminating resistor 3. If the adder/subtractor 6 performs addition, the output will be an in-plane waveform, and if subtraction is performed, the output will be a vertical waveform.

Problems to be Solved by the Invention However, in the above configuration, the reflective terminating resistor 3 must be switched depending on the ratio of magnetization components in the in-plane direction and the perpendicular direction of the perpendicular magnetic recording medium.

An object of the present invention is to provide a waveform equalization device that can equalize a reproduced signal from a perpendicular magnetic recording medium to a predetermined waveform, regardless of the ratio of magnetization components in the in-plane direction and perpendicular direction of the perpendicular magnetic recording medium. It's about doing.

Means for Solving the Problems The present invention inverts a reproduced signal from a perpendicular magnetic recording medium in the time axis direction and adds the inverted signal to the original reproduced signal to obtain a waveform-equalized signal. This is a waveform equalization device constructed as follows.

Effects of the present invention, regardless of the magnetization component ratio of the perpendicular magnetic recording medium,
Equalize the waveform to a processable waveform. Note that the present invention can also be applied to magnetic recording media oriented in the in-plane direction.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment of the waveform equalization device of the present invention. First, a signal input manually from the input terminal 1 is divided into predetermined constant time widths by the signal time divider 8. Each of the divided signals is inverted on the time axis by a signal time axis inverter 9. Further, the human input signal is delayed by a delay line 10. The adder 11 adds the outputs of the signal time axis inverter 9 and the delay line 10, and outputs the output from the output terminal 1.
Output to 2. The total delay time of the signal time divider 8 and the signal time axis inverter 9 is the same as the delay time of the delay line 10, and the outputs of both are synchronized and added by the adder 11.

FIG. 2 is a block diagram showing the configuration of the signal time axis inverter 9 in FIG. 1. The signal divided by the signal time divider 8 is sampled by the A/D converter 12 and stored in the memory 13. The memory 13 is controlled by a control circuit 14 which has a function of reading the sample values in the reverse order of storage, and the sample values read in the reverse order are returned to analog signals by the D/A converter 15 and sent to the adder 11. Output.

Next, the operation of this embodiment will be explained. 3rd m (a
), and the vertical waveform shown in (b) is g(t), then the superimposed waveform h in (C) of the same figure is
(t') is expressed as the following equation (1,))t(t)=
a−f(t)+b−g(t) (1) where a and b are constants determined by the in-plane and perpendicular magnetization component ratios of the perpendicular magnetic recording medium.

The waveform h(
-t) is h(-t)=a-f(-t)+b-g(-L)=a-f
(t)-b-g(t)"" (2). however,"(
The fact that t) is an even leap number and g(t) is an odd function was used.

Now, when formula (1) and formula (2) are added, h (t) + 11 (-t) = 2a - f (t)
... (3) becomes. Equation (3) expresses that when the superimposed waveform is added to the closed-axis inverted waveform at that time, an output proportional to the in-plane waveform is obtained. Since the output of the signal time axis inverter 9 is 11(-t) and the output of the delay line 10 is h(t), the output terminal 7 has an in-plane waveform f(t).
An output proportional to is obtained.

FIG. 4 is a diagram showing an example of the transition of the waveform of the present embodiment shown in FIG. Figure (c) shows the output waveform of the signal time axis inverter 9, figure (d) shows the output waveform of the delay line 10, and figure (e) shows the output waveform of the adder 11 (output equalization waveform). The output waveform (e) is equalized to an in-plane waveform.

In this embodiment, the adder 11 is used as shown in FIG. 1, but a subtracter may also be used in the same place. In that case, the output will be a vertical waveform.

Effects of the Invention As described above, according to the present invention, an asymmetric waveform reproduced from a perpendicular magnetic recording medium by a ring-shaped magnetic head can be equalized into a processable waveform.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a waveform equalizer according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a signal time axis inverter which is a component of an embodiment of the present invention. Figure 3 (
a) to (c) are waveform diagrams each showing an in-plane waveform, a vertical waveform, and an in-plane/vertical superimposed waveform reproduced from a magnetic recording medium, and FIG. 4 is a diagram showing a waveform transition in an embodiment of the present invention. The figure (a) shows the human waveform, the figure (b) shows the output waveform of the signal time divider 8, and the figure (c) shows the signal time axis inverter 9.
(d) shows the output waveform of the delay line 10, (e) shows the output waveform of the adder 11 (output equalization waveform), and FIG. FIG. 2 is a block diagram showing the configuration of a waveform equalization device. 1... Input terminal, 2... Differential delay line with tap, 3
...Reflection termination resistor, 4...Adder for weighting, 5...
・Amplifier, 6...Adder/subtractor, 7...Output terminal, 8.
...Signal time divider, 9...Signal time axis inverter, 10.
...Delay line! ! ...Adder, 12...A/D converter, 13...Memory 14...Control circuit, 15.
...D/A converter. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1 Figure 1

Claims (2)

[Claims] (1) a signal time divider that divides a reproduced signal from a perpendicular magnetic recording medium into a fixed time width; a signal time axis inverter that inverts each signal divided by the signal time divider in the time axis direction; A waveform equalization device comprising: a delay line that delays a reproduced signal; and an adder that adds the output of the delay line and the output of the signal time axis inverter. (2) The signal time axis inverter includes an A/D converter that samples the signal divided by the signal time divider, a memory that stores the sampled digital values, and a memory that stores the sampled digital values in the reverse order of the storage order. 2. The waveform equalization device according to claim 1, further comprising: a control circuit having a function of reading the sample value from the memory; and a D/A converter that converts the sample value read from the memory by the control circuit into an analog signal. .