JPS607857B2 - Waveform shaping circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is utilized for shaping the read signal electrical output waveform of a digital magnetic storage device.

In particular, the present invention relates to a waveform shaping circuit suitable for shaping discussion signals for high-density recording. [Prior Art] In a digital magnetic storage device such as a magnetic tape device or a magnetic disk device, the waveform of the electric signal taken from the magnetic head is as shown in Fig. 1 when there is sufficient recording density under normal conditions. The waveform will be like A.

This signal waveform includes binary information for each clock cycle. To reproduce this binary information, the amplitude peak is detected, and the peak point is one logic "1", and the clock cycle point between the peak points is another logic "0". . This is as indicated by the numbers in FIG. 1A. Therefore, in order to reproduce this binary information from an input analog signal, it is sufficient to detect the peak point of this input analog signal and generate a detection pulse. This requires a circuit that differentiates the input analog signal and detects the point where the differential value becomes zero, and also a circuit that detects the point where the differential value becomes zero, and the amplitude before and after the differential value becomes zero is sufficiently large to ensure that the point where the differential value becomes zero is the peak. It is composed of a circuit that guarantees that it is a point. Accordingly, circuits that ensure that the input signal has sufficient amplitude include a circuit that slices the argument signal waveform at a fixed slice level;
Alternatively, devices that monitor the average level of input signals are known. On the other hand, in recent years, the recording density of magnetic recording devices has increased, and the margin for recording density has become smaller. In this case, the read signal waveform becomes as shown in FIG. 1B, and for example, when logic "1"s occur continuously, interference occurs and its amplitude becomes small. [Problem to be solved by the invention] Conventional circuits such as those described above are not sufficient to reproduce accurate binary information from such waveforms.

In other words, when the recording density is high, the amplitude of the read waveform shown in FIG. Otherwise, it will be determined to be defective, and this cannot be fully guaranteed. For example, since the amplitude of the read waveform decreases when logic "1"s continue, such a circuit has the disadvantage that it is determined that there is not enough amplitude, making it impossible to accurately reproduce a binary signal. The present invention improves this by providing a waveform shaping circuit that can accurately reproduce binary information even when a magnetic recording device performs high-density recording and the amplitude of the read signal waveform becomes small due to interference. The purpose is to provide

[Means for solving problems]

The present invention provides a first method including a differentiator that inputs an analog signal having positive and negative peaks obtained in the read output of a magnetic recording device, differentiates the analog signal, and a circuit that detects the zero point of the output signal of this differentiator. a circuit, a second circuit that identifies that the analog signal is a valid signal of a predetermined level or higher, and a circuit that takes an AND of the output of the first circuit and the output of the second circuit. In the waveform shaping circuit, the second circuit has a double-wave rectifier that receives the output signal of the differentiator as an input, and a waveform shaping circuit that receives the output of the double-wave rectifier as an input, and has a waveform shaping circuit that receives the output signal of the differentiator. The present invention is characterized in that it includes an integrator whose integral value is reset at a time, and a comparator which compares the output of this integrator with a predetermined slice level.

[Effect]

In the circuit of the present invention, the input analog signal is differentiated, the differentiated waveform is integrated for each positive and negative cycle, and this integrated waveform is sliced at a predetermined level. Even if the information changes, binary information can be accurately reproduced.

〔Example〕

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

FIG. 2 is a block diagram showing a circuit according to an embodiment of the present invention.

In FIG. 2, the output of the magnetic head 1 is given to a differentiator 3 via an amplifier 2. The output of this differentiator 3 is given to a zero comparator 4 which compares the input signal with a zero point, and its output is given to a one-shot circuit 5. The output of this one-shot circuit 5 is applied to the input of yet another one-shot circuit 6. On the other hand, the output of differentiator 3 is branched,
It is connected to the input of a double-wave rectifier 7, and its rectified output is applied to an integrator 8 with a reset. The integral output is given to one input of comparator 9. The other input of this comparator 9 is given a slice level. This comparator 9
The output of the one-shot circuit 5 is connected to two inputs of the AND circuit 10 along with the output of the one-shot circuit 5. In the circuit shown in FIG. 2, the differentiator 3, zero comparator 4, and one-shot circuit 5 are the first circuits that generate a pulse when the differential value of the input signal is zero, and the one-shot circuit 6 is the first circuit that generates a pulse when the differential value of the input signal is zero. , the double-wave rectifier 7, the integrator 8, and the comparator 9 are a second circuit that detects that there is a predetermined level difference in the input analog signal.

FIG. 3 is a waveform diagram for explaining the operation of this circuit.

3A to 3I show signal waveforms at points a to i corresponding to those in FIG. A read signal a from a magnetic head of a magnetic recording device is amplified by an amplifier 2 and differentiated by a differentiator 3.

The output waveform b of the differentiator 3 is detected by a zero comparator 4 as to whether the signal is positive or negative, and a waveform c is obtained. The inversion position of this waveform c is detected by the one-shot circuit 5 to obtain a signal d. In this signal d, a pulse appears every time the differential waveform b crosses a zero point. The output of this one-shot circuit 5 is sent to a one-shot circuit 6 to obtain a signal e delayed by a time T.

The pulse width of this signal e is T2. It is assumed that these times T and T2 are sufficiently small compared to the period of the discussion signal. On the other hand, the output f of the double-wave rectifier 7 is integrated by an integrator 8.

Since this integrator 8 is reset by the signal e, the signal g rapidly drops at the peak position of the input analog signal.
Since this signal g has a waveform obtained by integrating the differential waveform of the input analog signal at each peak, it corresponds to the level of the input analog signal. The comparator 9 slices this signal g at the level indicated by the broken line in FIG. 3g to obtain a signal h. The period in which the signal h is at logic "1" is a guaranteed period in which a point at which a differential value of zero is detected in the input analog signal may be identified as a valid peak.
This signal h is logically ANDed with the above-mentioned signal d by an AND circuit, and becomes two-stage reproduction data i. [Effect of the invention] In this way, after differentiating the read waveform, the integration is performed every time the differential value of the discussion waveform becomes zero, and the amplitude of the integrated output corresponds to the amplitude between the positive and negative peaks of the read waveform. Therefore, when this amplitude is greater than a predetermined value, the differential value becomes zero, and the detected point can be accurately identified as a peak.

Therefore, even if interference occurs in the discussion signal when the same logic continues as the recording density increases, the peak can be accurately identified. This circuit has the excellent effect of reducing errors during planning and making accurate judgments even when checking after writing to a recording medium.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a read waveform of a magnetic storage device. FIG. 2 is a block diagram of a circuit according to an embodiment of the present invention. FIG. 3 is a waveform diagram for explaining the operation. 1...Magnetic head, 2
......Amplifier, 3...Differentiator, 4...Zero comparator, 5,6...One-shot circuit, 7...
...・Double wave rectifier, 8...Integrator with reset, 9
...Comparator, 10...AND circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Includes a differentiator that inputs an analog signal having positive and negative peaks obtained in the read output of a magnetic recording device and differentiates the analog signal, and a circuit that detects the zero point of the output signal of this differentiator. a first circuit; a second circuit that identifies that the analog signal is a valid signal of a predetermined level or higher; and an AND of the output of the first circuit and the output of the second circuit. In the waveform shaping circuit, the second circuit includes a double-wave rectifier that receives the output signal of the differentiator as input;
an integrator whose input is the output of the double-wave rectifier and whose integral value is reset for each zero point detected by the first circuit;
A waveform shaping circuit comprising: a comparator that compares the output of the integrator with a predetermined slice level;