JPH0433526Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic disk recording and reproducing apparatus for recording and reproducing digital signals using a magnetic disk such as a floppy disk.

[Conventional technology]

The recording density on a magnetic disk is high on the inner tracks and low on the outer tracks. For this reason,
When the outer track is scanned during playback and the head output signal obtained thereby is differentiated for peak detection, a saddle-shaped differential waveform may occur. If the intermediate level of this saddle falls below the zero level of the comparator for peak detection, false pulses will occur. To solve this kind of problem, the cutoff frequency of the low-pass filter inserted before the differentiating circuit is lowered during outer track scanning, and by attenuating high-frequency components, a saddle-shaped waveform that crosses the zero level is created. It is already known that it can prevent the occurrence of

In addition, in magnetic disk drives, data is written using the saturation recording method and data is erased by overwriting, so if the value of the recording current is made the same between the inner and outer tracks of the disk, the recording density There is a possibility that unerased data noise may occur on the outer track where the data is low. This kind of problem can be solved by increasing the recording current when scanning the outer tracks of the disk.

[Problem that the invention attempts to solve]

By the way, conventionally, lowering the cut-off frequency of the low-pass filter and increasing the recording current value in the outer track were performed independently, which inevitably resulted in a complicated circuit configuration.
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic disk recording/reproducing apparatus that can perform both filter switching and recording current switching with a simple circuit.

[Means for solving problems]

The present invention to solve the above problems includes a rotating mechanism for rotating a magnetic disk as a recording medium, a magnetic head for recording and reproducing, a mechanism for moving the magnetic head in the radial direction of the disk, and a rotating mechanism for rotating a magnetic disk as a recording medium, a mechanism for moving the magnetic head in the radial direction of the disk, and A recording circuit including a recording current switching circuit for switching the value of the current flowing through the magnetic head, a low-pass filter for correcting a signal waveform obtained from the magnetic head during reproduction, and a low-pass filter for switching the frequency characteristics of the low-pass filter. a reproducing circuit including a frequency characteristic switching circuit; a scanning track information circuit for obtaining a signal indicating a scanning track position of the magnetic head on the disk; a memory for storing a signal indicating a specific track on the disk; Based on a comparison between a signal indicating the track to be scanned from the information circuit and a signal indicating the specific track obtained from the memory, it is determined whether the track to be scanned is on the outer or inner side of the specific track, and recording is performed. When the track to be scanned is on the outer circumferential side of the specific track, the recording current switching circuit is controlled so that a larger recording current is passed through the magnetic head than when it is on the inner circumferential side, and the scanning is performed during reproduction. a comparator circuit that generates an output for controlling the frequency characteristic switching circuit so that when the track is on the outer circumferential side of the specific track, the cutoff frequency of the low-pass filter is lower than when it is on the inner circumferential side. This relates to playback devices.

[Effect]

In the above invention, a memory for storing a specific track is provided, and the specific track stored therein is used for both filter switching and recording current switching. The comparison circuit compares a signal indicating a track scanned by the magnetic head with a signal indicating a specific track obtained from the memory, and this output is used for both filter switching control and recording current switching control. Therefore, both types of switching control can be performed with a simple circuit configuration.

〔Example〕

Next, a flexible magnetic disk recording/reproducing apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. The magnetic disk drive device shown in FIG.
A magnetic disk 1 is rotated by a disk rotation mechanism 2, and a magnetic head 3 for both recording and reproduction purposes performs recording or reproduction of digital signals. The magnetic head 3 includes a core 4 having first and second windings 5,
6 is wound around the gap 7 for recording or reproduction. The head 3 is supported by a schematically shown head carriage 8, and is moved in the radial direction of the disk 1 by a head moving mechanism (head positioning mechanism) consisting of a lead screw 9 and a stepping motor 10. The first and second windings 5 and 6 of the head 3 are connected in a center-tap manner, the center tap is connected to a common ground line, and a pair of lead wires 11 and 12 are led out from both ends.

The recording circuit 13 connected to the first and second windings 5 and 6 includes a NOT circuit 14, a D-type flip-flop 15, and first and second NAND gates 16 and 1.
7. First and second transistors 18 and 19; a current control circuit 2 connected between the emitters of the pair of transistors 18 and 19 and a power supply terminal 20;
1. It includes a transistor 22 that grounds the emitters of a pair of transistors 18 and 19 during reproduction. In this recording circuit 13, a recording data line 23
is connected to the flip-flop 15 via the NOT circuit 14.
It is connected to the clock terminal (C). A recording gate signal line 24 for providing, for example, a high level signal in the recording mode is connected to the flip-flop 1.
5 and one input terminal of a pair of NAND gates 16 and 17, respectively. The Q output terminal of flip-flop 15 is connected to the first NAND gate 1.
The output terminal is connected to the other input terminal of the second NAND gate 17 and to the input terminal (D) of the flip-flop 15. first and second
NAND gates 16 and 17 are the first and second PNP
It is connected to the bases of type transistors 18 and 19. Therefore, when the outputs of NAND gates 16 and 17 are at a low level, transistors 18 and 19 are turned on. First and second transistors 18, 19
are connected between the power supply terminal 20 and one ends of the first and second windings 5 and 6, respectively. Therefore,
A recording current flows through the windings 5 and 6 only while the transistors 18 and 19 are on. The current control circuit 21 controls the current flowing through the pair of transistors 18 and 19.
A current control transistor 26 is connected between the emitter of 9 and the power supply terminal 20 via a resistor 25.
, resistors 27, 28, and 29 for setting the bias of this transistor 26, and a transistor 30 for selectively connecting the resistor 29 to the base of the transistor 26. In this current control circuit 21, when the bias switching transistor 30 is off, the base current of the current control transistor 26 becomes small, and this collector current also becomes small. On the other hand, when the bias switching transistor 30 is on, the base current of the current control transistor 26 becomes large, and this collector current also becomes large.

Regeneration circuit 3 connected to windings 5 and 6 of head 3
1 is a head amplifier 32, a low pass filter 3
3, differentiator 34, zero volt comparator 35,
It has a pulse shaping circuit 36 in order, and further includes a control circuit 37 for switching the frequency characteristics of the filter 33.
has.

Reference numeral 38 is a track memory, which stores a specific track number according to the present invention. In this example, 80 tracks from track 00 to track 79 are provided concentrically on the disk 1, and track number 43 among these tracks is written in the memory 38. Track number 43 is always read from memory 38 when the device is powered on.

39 is a scanning track information circuit;
It outputs a scanning track signal indicating the track to be scanned. This scanning track signal is provided by the head 3 reading an address signal from the disk 1 or by the output of an up-down counter that counts track positions. When the scanning track is known from the output of the up-down counter, the up-down counter is reset in correspondence with the zero scanning track, and the step pulse and step direction signal of the stepping motor 10 given from the host device are input to the up-down counter. It is obtained by inputting the step pulse to the step direction signal, determining up or down using the step direction signal, and counting the step pulses.

A comparison circuit 40 compares the scanning track signal obtained from the scanning track information circuit 39 with the specific track signal obtained from the track memory 38. The output line of this comparison circuit 40 is connected to the base of the recording current switching transistor 30 and the filter switching control circuit 37.
It is connected to the. In this example, disk 1
Since track zero is at the outermost periphery, when the scanning track number is 43 or less, a high level output is obtained from the comparator circuit 40 indicating that it is smaller than the specific track number 43, that is, on the outermost periphery; is 44 to 79, that is, when the inner circumferential side is being scanned, a low level comparison output is obtained.

The filter switching control circuit 37 and the filter 33 are formed as shown in FIG. That is, the filter 33 is a low-pass filter including a resistor R ₁ , capacitors C ₁ , C ₂ , inductance L ₁ , etc., and the control circuit 37 is configured by connecting a transistor 41 between the capacitor C ₂ and the ground. There is. Since the base of the transistor 41 is connected to the comparator circuit 40 in FIG.
When a high level output indicating that the scanning track is on the outer circumferential side is generated, in response to this, the transistor 41 is turned on, the capacitor _C2 is connected, the cutoff frequency of the low pass filter 33 is lowered, and the reproduced signal is Harmonic components are removed. On the other hand, when the comparator circuit 40 generates a low-level output indicating the inner scanning track, the transistor 41 is turned off and the capacitor _C2 is disconnected, so the high-frequency component of the filter 33 is compensated and the reproduced waveform is Peak shift is reduced.

When recording data corresponding to the reproduced data shown in FIG. 3E is written to the disk 1 using the apparatus shown in FIG. . At this time, if the head 3 is located on the outer side of the track number 43, the transistor 30 is turned on in response to the output of the comparator circuit 40, so the collector current of the transistor 26, that is, the recording current increases, and the recording current increases. There is less unerased data due to writing. On the other hand, when the head 3 is on the inner track, the transistor 30 is turned off and the collector current of the transistor 26, that is, the recording current decreases. As a result, recording with good resolution becomes possible.
Since the head 3 does not necessarily scan regularly from the outermost track to the innermost track, but takes any track position, the comparing operation by the comparing circuit 40 is always performed.

In the reproduction mode, the recording circuit 13 is substantially disconnected from the head 3. Figure 3 A on disk 1
If the magnetization pattern shown in is generated,
The waveform shown in FIG. 3B is obtained at the output of the head amplifier 32. Now, if there is a distortion called a shoulder at point a of the waveform of the amplifier 32 because the outer track with low recording density is being scanned, then a distortion called a saddle will appear at point b of the output waveform of the differentiator 34 in FIG. 3C. A depression is formed, and when this depression becomes deeper, comparator 3
5, a comparison output shown as c is generated, and as a result, there is a possibility that a miss pulse shown as d will be included in the reproduced data. Therefore, in this embodiment, the same memory 38 and comparator circuit 4 are used for controlling recording current switching to determine whether the scanning track is on the outer circumference side or on the inner circumference side.
0 is used for determination, and the frequency characteristics of the low-pass filter 33 are switched. During outer track scanning, the cutoff frequency of the low-pass filter 33 is lowered, so the harmonic components of the output of the amplifier 32 shown in FIG. 3B are removed, and the depression in the saddle of the differential waveform shown in FIG. 3C becomes shallower. The comparator 35 crosses the zero level and miss pulses no longer occur. On the other hand, when scanning the inner track, the problem due to the saddle does not substantially occur due to the high recording density, but the resolution of the waveform deteriorates. Therefore, in this embodiment, the low pass filter 3
The cutoff frequency of No. 3 has been raised to compensate for the high frequencies and prevent a drop in resolution.

The present invention is not limited to the embodiments described above, but can be modified in various ways. For example, the current control circuit 21 may be configured such that a resistor is disposed in a circuit through which a recording current flows, and the current value between the inner circumferential side and the outer circumferential side is switched by switching the resistor with a switch. Further, the characteristics of the filter 33 may be changed by changing the inductance value.

[Effect of idea]

As is clear from the above, since the recording current and the frequency characteristics of the filter are switched using a common memory and comparison circuit, the configuration can be simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a magnetic disk recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the filter and control circuit of FIG. 1, and FIG. 3 is a block diagram showing points A to E in FIG. 1. FIG. DESCRIPTION OF SYMBOLS 1... Disk, 2... Rotating mechanism, 3... Magnetic head, 13... Recording circuit, 21... Recording current control circuit, 33... Low pass filter, 37... Switching control circuit, 38... Track memory, 40...
Comparison circuit.

Claims (1)

[Claims for Utility Model Registration] A rotation mechanism for rotating a magnetic disk as a recording medium, a magnetic head for recording and reproduction, a mechanism for moving the magnetic head in the radial direction of the disk, and a mechanism for moving the magnetic head in the radial direction of the disk during recording. A recording circuit including a recording current switching circuit for switching the value of the flowing current, a low-pass filter for correcting the signal waveform obtained from the magnetic head during reproduction, and a frequency characteristic switching circuit for switching the frequency characteristic of the low-pass filter. a reproducing circuit comprising; a scanning track information circuit for obtaining a signal indicating a scanning track position of the magnetic head on the disk; a memory for storing a signal indicating a specific track on the disk; and a signal obtained from the scanning track information circuit. Based on a comparison between a signal indicating a track to be scanned and a signal indicating a specific track obtained from the memory, it is determined whether the track to be scanned is on the outer or inner side of the specific track, and the scanning is performed at the time of recording. The recording current switching circuit is controlled so that when the track is on the outer circumference side of the specific track, a larger recording current is passed through the magnetic head than when it is on the inner circumference side. a comparator circuit that generates an output that controls the frequency characteristic switching circuit so that the cutoff frequency of the low-pass filter is lower when the cutoff frequency is on the outer circumference side than when it is on the inner circumference side.