JPS6355780A - Flexible magnetic disk device - Google Patents

Abstract

PURPOSE:To optimize the reproduction characteristic of upper and lower heads by providing a filter changing circuit consisting of a driver gate, a switching transistor, a resistor and a capacitor in a double face type flexible magnetic disk device. CONSTITUTION:Magnetic heads 3u, 3l of upper face and lower face are provided in radial direction at a specified distance. A head selecting signal that selects one of upper and lower magnetic heads 3, 3l is supplied to a switching transistor (TR) through a driver gate 14 in a filter changing circuit 15. As the TR is made ON or OFF by the selecting signal 6, a capacitor C2 is connected in parallel to a capacitor C1 of an LPF 9 or cut off, and the transmission characteristic of the LPF changes. Thus, the difference of waveform characteristic due to positional deviation between the heads 3u, 3l can be eliminated, and the optimizing of reproduction characteristic of upper and lower heads is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The invention of B relates to a filter switching circuit that is effective when applied to a double-sided flexible magnetic disk device.

[Conventional technology]

Figure 2 shows the positional relationship between the heads and the medium when two magnetic heads, upper and lower, perform recording or reproducing operations on a magnetic recording medium in an existing double-sided flexible magnetic disk drive. .

In the figure, (1) is a magnetic disk recording medium, (lu)
, (11) are the top and bottom of (1), each recording and playback surface, (2)
is the center of rotation when (1) rotates, (3u), (31)
In the radial direction of (1), there are upper and lower recording and reproducing magnetic heads, (4u
), (41) are the upper and lower magnetic head supports that support (3u) and (31), and (4) is the head support (4u).
), (41) to constitute one magnetic head support assembly, (5) is (4)
In the direction of movement indicating movement in the radial direction above (1),
be.

Also, in the figure, the magnetic helad carriage (4) is shown at the outermost periphery (
When the head (3) is on track OO), the upper and lower track positions on the recording medium (1) are numbered (00, 01,
...) is shown. Figure 3 shows a conventional reproducing circuit, in which (6) is a head selection signal that selects either the upper or lower magnetic head (3u) or (31), and (7) is a head selection signal that selects one of the upper and lower magnetic heads (3u) and (31). Head selection circuit that selects and extracts the reproduced signal from one head; (8) is a preamplifier that amplifies the reproduced signal; (9) is a low-pass filter that removes high-frequency noise; (io) differentiates the reproduced signal Differentiator circuit, (11) converts the differential signal to the reference voltage (usually Ov)
(12) is a comparison circuit that performs waveform shaping, and (12) is a one-shot circuit that shapes a predetermined pulse at the change point (rising or falling) of the signal after waveform shaping.
13) is a pulsed reproduction pulse signal. Also,
C and C1 are capacitors, R is a resistor, and L is an inductor.

In FIG. 2, the upper head (3u) of the head (3) (
Side ``1'') and lower head (311 (Side ``0'')
), there is a difference between the head pressure glD (8) - rack), and while maintaining this state, the media (1) is moved toward the rotation center (2) (inner circumference) or in the opposite direction. Since the lower head (31) moves in the direction (outer periphery) (5), it is always on the outer periphery side compared to the upper head (3u).

Therefore, the reproduction output from the lower head (31) that reproduces the outer side, which has a lower magnetic recording density than the inner side, has characteristics (resolution, output voltage) that are too high compared to the upper head (3u). , recorded magnetic signals cannot be correctly identified (
errors may occur. Next, in FIG. 4, (a) is the output signal waveform of the low-pass filter (9) shown in FIG. 3, and (b) is the output signal waveform of the differentiating circuit (10). '') and lower head (31) (side ``0'') track number 00 (outer circumference)
and track number 79 (inner circumference).

Hereinafter, the conventional operation will be explained based on FIGS. 3 and 4. As explained in FIG. 2 above, the reproduction output of the lower head (31) has a higher resolution than the reproduction output of the upper head (3u), and the reproduction output is also larger. , side ″0 of l-rack number 00
``There may be shock noise S1 as shown in the solid line of the output waveform (a), and this differential waveform (b) is
This produces S2 called saddle noise that reaches up to the v level. As is already known, when this saddle noise S2 occurs, the comparator circuit (11) in Figure 3 compares it with Ov and erroneously shapes the waveform and generates extra pulses, deteriorating the reproduction characteristics. It is. As shown by the dotted line in Fig. 4, if the resolution is lowered so that the shibble noise S1 and saddle noise S2 will not occur at the side "0" output of l-rack number 00, then the side "1" In track number 79, S/H deterioration due to output decrease,
Deterioration of the output signal waveform occurs due to the decrease in resolution, which deteriorates the reproduction characteristics on the inner track. Therefore, conventionally, a method (inner/outer track switching method) has been used in which the resolution is switched in the reproducing circuit depending on the track number, and the difference in reproduction output and resolution between the inner and outer tracks is reduced. However, as mentioned above, side "0"
Since there is a difference in playback output between side 1" and side 1", the outer circumferential side should be set so that there is no noise on the side "O".
On the inner circumferential side, a switching circuit was set up to increase the playback output and resolution of side "1", so it was inevitable to use side "1".
On the 1" side, the resolution can only be raised to the limit that does not cause shoring noise on the side "0" side, and the resolution has always been set low. In other words, with the inner/outer circumference switching method, the playback output of the upper and lower heads The difference cannot be completely eliminated, and the characteristics of only one head are always optimized, while the other head is inevitably subject to some degree of characteristic deterioration.

[Problem that the invention seeks to solve]

Flexible disk devices with conventional playback circuits have waveform characteristics (playback waveforms) caused by misalignment between the top and bottom of the head.
If the difference cannot be eliminated, either the upper or lower head,
Alternatively, the reproduction characteristics cannot be optimized for both, leading to deterioration of the reproduction characteristics.

This invention was made in order to solve the above-mentioned problems, and it is a switch filter that can set the characteristics of the reproducing circuit to be appropriate for any head by taking into account the positional deviation between the upper and lower heads. The purpose of this invention is to obtain a flexible disk device having the following characteristics.

[Means for solving problems]

A flexible disk device according to the present invention includes a switching transistor, a driver gate and a resistor,
It has a filter switching circuit consisting of a capacitor, and optimizes the filter according to the head selection signal, and makes the waveform characteristics the same on the same circumference.

[Effect]

The switching circuit using the switching transistor in this invention is turned on or off by the head selection signal,
Correct the difference in waveform characteristics due to head position deviation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, (3u) and (31) are upper and lower magnetic heads for recording and reproducing, respectively, (6) is a head selection signal,
(7) is the head selection circuit, (8) is the preamplifier, (9)
is a low-pass filter, (10) is a differentiating circuit, (11) is a comparison circuit, (12) is a one-shot circuit, and (13) is a reproduction pulse signal, and these have the same configuration as the conventional one.
The same reference numerals as in the figure are given. (14) is a driver gate which receives the head selection signal (6) and drives a switching transistor (in this example, an FET (field effect transistor)) indicated by Tr, and turns it on and off into the low-pass filter (9). The transfer characteristic of the low-pass filter (9) is changed by connecting or disconnecting the capacitor C2 in parallel with the capacitor CI located in the lower pass filter (9). (15) is the driver gate (14)
), a switching transistor T", a capacitor C2, and a resistor R. The switching filter (15) is supplied with a power source Vee in order to operate the switching transistor T".

A detailed explanation will be given based on FIGS. 1 and 4.

In FIG. 1, when the capacitor C2 in the switching filter (15) is disconnected, the characteristics of the low-pass filter (9) are the same as the conventional one. The playback characteristics at this time have a waveform as shown by the solid line in FIG.
In ~, shoulder noise S1 and saddle noise S
On the other hand, as shown by the dotted line in FIG. 4, if the resolution is kept low so as not to generate these noises, the S/ The output signal waveform deteriorated due to the deterioration of the N ratio and the decrease in resolution, resulting in deterioration of the reproduction characteristics on the inner track.

Therefore, in this invention, by switching the characteristics of the low-pass filter (9), the difference in resolution between side "0" and side "1" is corrected, so that shoulder noise does not occur on the outer circumference side, and the resolution on the inner circumference side is corrected. Make sure there is no decline.

In FIG. 1, in order to switch the characteristics of the low-pass filter (9), a capacitor C2 included in a filter switching circuit (15) is connected in parallel with a capacitor C1 in the low-pass filter (9).

Here, the value of the added capacitor C2 is selected so that the waveform of side "0" in FIG. can. That is, in FIG. 1, when the switching transistor in the switch filter (15) is turned on in response to the side "0" of the head selection signal (6), the capacitor C2 is added, and the side is "1", By turning off C2 so that it is not added, the reproduced waveform will be as shown in the dotted line when side "0" is selected and as shown in the solid line when side "1" is selected in Figure 4. You can do it like this. This reduces the resolution on the side -〇'' side to the same level as on the side 1'' side, eliminates the generation of shoulder noise S1 and saddle noise S2 on the outer track (and eliminates the generation of shoulder noise S1 and saddle noise S2 on the inner track). As the resolution is the same as that of side 1'', the difference in waveform characteristics between the upper and lower heads can be eliminated, and the characteristics of both the upper and lower heads can be optimized.What is important here is that the characteristics of the low-pass filter (9) are Capacitor C
When C1 and C2 are connected in parallel, the cutoff frequency is lower and the amount of attenuation of the high frequency signal component becomes larger than when only C1 and C2 are connected, thereby realizing a reduction in resolution in the reproducing circuit. This is a known fact due to the transfer characteristics of filters in network theory.

In the above embodiment, the filter switching port m (15) is added to the low-pass filter (9) in the reproducing circuit, but it is also added to the input section of the preamplifier (8) to reduce the load on the head during reproducing. The waveform characteristics may be changed by switching the resistance value. Alternatively, the waveform characteristics may be changed by adding it to the differential constant setting section of the differentiating circuit (10) and switching the cutoff frequency of the differentiating circuit. Further, as the switching transistor, a digital transistor or other switching element may be used in addition to the FET.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to eliminate the difference in waveform characteristics (playback waveform) due to positional deviation of the magnetic head on the track, so it is possible to optimize the playback characteristics for both the upper and lower heads, resulting in improved performance. improvement is expected.

[Brief explanation of the drawing]

FIG. 1 is a reproduction circuit diagram including a filter switching circuit according to an embodiment of the present invention, FIG. 2 is a sectional view showing the positional relationship of the head medium of an existing double-sided flexible disk device, and FIG.
The figure shows a conventional reproducing circuit without a filter switching circuit, and FIG. 4 is a schematic diagram of the output signal waveform of the low-pass filter and the output waveform of the differentiating circuit shown in FIG. 1. (3) is a magnetic head;
(6) is the head selection signal, (14) is the driver game 1
-1Tr is a switching transistor, R is a resistor, C2
is a capacitor, and (15) is a filter switching circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa (and 2 others) No. 1 Figure 14. Doufu Per γ-t t5 Sd Letter Kirikikyo Nagi f1 6. To 1. Do l translation number 2 figure 3 figure 4 tiger ty7 number 00 tiger 1. F number 979

Claims (1)

[Claims] In a flexible disk device equipped with a magnetic head having pieces on side 0 and side 1, depending on the selection of the head pieces on each side 0 and side 1 for correcting the waveform characteristics of the output signal of the magnetic head, A flexible magnetic disk device comprising a filter switching circuit consisting of a driver gate, a switching transistor, a resistor, and a capacitor.