JPS60157768A - Magnetic memory - Google Patents

Abstract

PURPOSE:To increase the amplitude margin of a gate signal detecting circuit by amplifying nonlinearly a read analog signal. CONSTITUTION:As shown in figure (a), a nonlinear circuit 6 consists of diodes 7 and 8 and a resistance 9 and amplifies an input signal A by means of the nonlinear characteristics of diodes 7 and 8 with the amplification factor of figure (b). In other words, no current flows to both diodes 7 and 8 before the voltage of about 0.6V is applied forward. Then the voltage is produced at the output side. Therefore no voltage is virtually produced at an input part of a gate signal detecting circuit 4 when the read signal has a low level as long as the voltage is previously set at <=0.6V at a part where no read waveform is needed, i.e., a place near a base line of a low density part. While the amplification factor is increased as the level of the read signal rises up, and a peak signal is delivered with a high level. Thus it is possible to increase the setting range of a slice level SL of the circuit 4 up to about the base line. Therefore the amplitude margin can be increased enough.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a magnetic storage device such as a magnetic disk device,
In particular, the present invention relates to a magnetic storage device improved to eliminate noise signals generated when magnetic information is read by a thin film magnetic head.

(bl) Prior Art and Problems Conventionally, magnetic disk drives generally use a differential method as a method for reproducing magnetic information written on a disk recording medium. It is characterized by a configuration in which the peak position of the analog signal is detected by differentiating the analog signal, and the recorded information is reproduced, and it depends only on the expansion of the analog signal and is unrelated to the absolute level. Strong against amplitude fluctuations (Traditionally used as a method for reproducing magnetic information).

FIG. 1 shows a block diagram of an example of a magnetic storage device using this differential method, and its operation will be explained with reference to the signal waveform diagram in FIG. The analog signal waveform A shown in Figure 2(a) is manually input to the differentiating circuit 2 and the gate signal detection circuit 4 in parallel.The differentiating circuit 2 differentiates the input signal A and detects the peak position as the signal B shown in Figure 2(a). The differential signal B is output to the circuit 3. This differential signal B is located at the point where the peak point of the read signal A becomes the O level.The peak position detection circuit 3 detects the O level axis crossing position of the input differential signal B. By doing so, the peak position of the read signal is detected, and a rectangular wave signal C synchronized with the peak position is outputted to one input terminal of the AND circuit 5.

On the other hand, the read signal inputted to the data 1 signal detection circuit 4 has +A at a predetermined level V as shown in FIG.
The signal E is sliced into the gate 1 having a slice width, and is input to the other input terminal of the AND circuit 5. The AND circuit 5 ANDs the input signal C and the signal F and outputs the signal F.

In this case, if the operating density range of the device Q is wide, the readout waveform approaches the baseline (0 level) in the low density portion, as shown by the symbol N1 in tel B of FIG. 2, and there is no sudden change. Therefore, when trying to detect a peak from a differential waveform, in addition to the original peak value, a peak signal due to noise in the low-density portion (see Figure 2 (see symbol N2 in alC)) is detected, making it appear as if the peak is due to noise. In order to remove the peak due to this noise, as mentioned above, the gate signal detection circuit 4
The readout signal A is sliced at an appropriate level to produce data 1 to signal E, and original peaks and peaks due to noise are distinguished.

In recent years, there has been a demand for higher writing density, and in response to this demand, thin-film magnetic heads have been used for writing and reading heads. Because of this, noise often occurs in the baseline,
It is necessary to set a high level width of the slice level V, which has the disadvantage that the setting range of the slice level becomes narrow and the amplitude margin becomes small.

(C1 Purpose of the Invention The present invention was devised in view of the above-mentioned conventional drawbacks,
By nonlinearly amplifying the readout analog signal,
The purpose of this invention is to provide a magnetic recording device that can provide a large amplitude margin in a gate signal detection circuit.

(d+) According to the present invention, the structure and object of the invention is to provide a differentiation circuit for differentiating an analog signal read by a magnetic head, a peak position detection circuit that takes the O-axis crossing position of the differential signal as a peak position, and It has a gate signal detection circuit that slices an analog signal at a predetermined level value, and an AND circuit that takes the logical conclusion of both outputs of the peak position detection circuit and the gate signal detection circuit, and information is recognized by the output of the AND circuit. This is achieved by a magnetic memory device characterized in that a nonlinear circuit is provided at the input stage of the gate detection circuit.

tel Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a block diagram of a magnetic storage device according to one embodiment, FIG. 4 is a configuration diagram of an example of the nonlinear circuit of FIG. 3, and FIG.
The figure is a signal waveform diagram for explaining the operation of this magnetic storage device.

As shown in the block diagram of FIG. 3, in this embodiment, the gate signal detection circuit 4 of the conventional magnetic recording device A shown in FIG.
The feature is that the nonlinear circuit 6 is placed in the front stage of the circuit. This nonlinear circuit 6 uses, for example, a circuit consisting of a diode 7.8 and a resistor 9 as shown in FIG. The input signal A is amplified with an amplification factor of bl.That is, the diode F'7.8 has an amplification factor of approximately 0.6 in the forward direction.
When a voltage of about V is applied, current flows and a voltage is generated on the output side. Therefore, if the voltage near the baseline that falls on the unnecessary part of the spread waveform, that is, the low-density part, is set to 0.6 V or less in advance, when the read signal level is low, almost no voltage will be present at the input part of the gate signal detection circuit. Does not occur. On the other hand, as the read signal level increases, the amplification factor increases, and the peak signal is output as a large signal.

This is due to the function of the nonlinear circuit 6, which converts the readout signal A shown in FIG. 5 into the signal G, and reduces the amplification in the portions where the output level is low, and increases the amplification in the portions where the output level is high. be. By obtaining this signal waveform G, the setting range of slice level SL of data 1 to signal detection circuit 4 can be set close to the Heiss line (0 level), and the magnetic recording device can have a sufficiently large amplitude margin. becomes.

(fl Effects of the Invention As is clear from the above explanation, the present invention adds a nonlinear circuit to the front stage of the gate signal detection circuit, and amplifies the small output part of the read signal waveform with a small amplification factor and the large output part with a large amplification factor. By making it possible to detect signals amplified at
- A magnetic recording device capable of increasing the amplitude margin of a signal detection circuit is developed.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional magnetic recording device, Figure 2 fa
t is a signal waveform diagram for explaining the operation of a conventional magnetic recording device; FIG. 2 is a readout waveform diagram by a thin film head;
FIG. 3 is a block diagram of an embodiment of the magnetic recording device according to the present invention, FIGS. 4(a) and (bl) are a circuit configuration diagram and characteristic diagram of an example of the nonlinear circuit shown in FIG. In order to explain the operation of the example, a signal waveform diagram is shown.In the figure, 1 is a magnetic head, 2 is a differential circuit, 3 is a peak position detection circuit, 4 is a gate signal detection circuit, 5 is an ant circuit, 6 is a nonlinear circuit, 7 and 8 are diodes, and 9 is a resistor. Fig. 1 Fig. 2 (Q) Fig. 2 (b) Fig. 3 Fig. 4

Claims (1)

[Claims] a differentiation circuit that differentiates an analog signal read by a magnetic head; a peak position detection circuit that sets the O-axis crossing position of the differential signal as a peak position; and a gate signal detection circuit that slices the analog signal at a predetermined level value; A magnetic storage device comprising an AND circuit that performs a logical product of both outputs of the peak position detection circuit and the gate signal detection circuit, and which recognizes information based on the output of the AND circuit, wherein a nonlinear circuit is provided at an input stage of the gate detection circuit. A magnetic storage device characterized by being provided with.