JPS5857676A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To keep a frequency spectrum for the reading signal constant, by changing the number of revolutions of a magnetic medium in response to the position of a magnetic head in its radius direction. CONSTITUTION:The signal read by a mgnetic head 3 is amplified by an amplifire 7 and then fed to a radius position detecting circuit 8. For the signals read by the head 3 and fed to the amplifier 7, a group of three signals, that is, an FLG signal, a radius position detecting information DPD signal and a so-called data DRD signal is repeated with each prescribed interval. These three signals are modulated and written into a magnetic medium 1. The circuit 8 detects the FLG signal from such input signals and also selects the subsequent DPD signal to feed it to a rotational frequency directing circuit 9. The output of a shifting speed detector 6 which detects the shifting speed of an actuator 4 is fed to the other input terminal of the circuit 9. The circuit 9 decides the rotational frequency indicated by a motor 2 based on the input signals S1 and S2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device useful as a large-capacity file memory.

As is well known, electronic '$11' FM systems require memory regardless of the size of the system.

In particular, file memory that stores large amounts of data plays an important role, and digital magnetic recording devices that use the principle of digital magnetic recording, such as magnetic disks, are used as file memory. It is being

Figure 1 shows the read waveform of an isolated bit written on a magnetic medium in a conventionally used digital magnetic storage device of this type.
b) shows the distribution of reading υ level days over time t. The waveform in the same figure (c)) is approximately 1/1+
It can be formulated as (x-)2 and has a half width of 2a. This 2
2T is the value obtained by dividing a by the relative speed between the magnetic medium and the magnetic head.
a ((b) in the same figure) is a parameter that determines the frequency spectrum of the signal, and this spectrum is expressed as [e with the angular frequency being ω.

By the way, in a device that rotates a disk-shaped magnetic medium at a constant rotation speed, such as a conventional magnetic disk device, the relative speed between the magnetic medium and the magnetic head is determined by the position of the magnetic head on the magnetic medium. changes. For this reason,
A phenomenon occurs in which the above-mentioned signal half width 2Ta changes and the frequency spectrum changes. In addition, in coated magnetic disk media manufactured using the spin code method, the thickness of the magnetic layer of the magnetic medium becomes thicker on the outer circumferential side of the medium, so that 2a described above changes. There is a difference in the frequency spectrum between the inner and outer circumferences.

On the other hand, in a signal processing circuit, a low-pass filter is generally used to remove high-frequency noise contained in the signal, and its cutoff frequency is set to fc: 1.5/2Ta in relation to the frequency spectrum described above. is considered desirable. Therefore, when the signal half-width 2Ta changes as described above, it is difficult to continuously change the cutoff frequency f accordingly. For this reason, there is a method in which low-pass filters are divided into several stages and each has a different cutoff frequency.
It is inevitable that the circuit will become larger.

As described above, while the signal half-width 2Ta changes depending on the position on the medium, the cutoff frequency of the low-pass filter is not set appropriately, causing distortion in the read waveform and increasing reading errors. In addition, when waveform equalization technology using a transversal filter is used for high-density signal processing, changes in the signal half-width 2Ta bring about changes in the waveform equalization conditions, so the above-mentioned cutoff of the low-pass filter is required. As with the off-frequency setting, significant waveform distortion occurs and signal reading errors increase.

The present invention has been made in view of the above circumstances, and its purpose is to provide a magnetic disk device in which the frequency spectrum of read multi-signals is constant regardless of the position of the magnetic head on the magnetic medium. It's there.

In order to achieve such an object, the present invention provides a speed detection means for detecting the speed at which the magnetic head moves in the radial direction of the magnetic medium by an actuator, and a speed detection means for detecting the radial position of the magnetic head on the magnetic medium. radial position detection means;
A rotation speed indicating circuit is provided for indicating the rotation speed of a motor that rotates the magnetic medium, and the rotation speed indicating circuit is configured to read data from the magnetic medium by the magnetic head based on outputs from the speed detecting means and the radial position detecting means. It is configured to calculate and output the rotation speed such that the frequency spectrum of the signal is always constant. Hereinafter, the present invention will be explained in detail using Examples.

FIG. 2 is a block diagram showing one embodiment of the present invention.

In the figure, 1 is a disk-shaped magnetic medium, 2 is a motor that rotates the magnetic medium 1, 3 is a magnetic head, 4 is an actuator that moves the magnetic head 3 in the radial direction of the magnetic medium 1, and 5 is a motor that rotates the magnetic medium 1. a power amplifier that supplies current; 6 a speed detector that detects the moving speed of the actuator; γ an amplifier that amplifies the output of the magnetic head 3;
8 is a radial position detection circuit that detects the radial position of the magnetic medium 1 of the magnetic head 3; 9 is a rotation speed indicating circuit that indicates the rotation speed of the motor 2; and 10 is a rotation speed indicating circuit that is equal to the instruction of the rotation speed indicating circuit 9. This shows the motor control circuit that rotates the motor.

In the magnetic tape device having the above configuration, the signal read by the magnetic head 3 is amplified by the amplifier 7 and input to the radial position detection circuit 8. Here, as the read signal of the magnetic head 3 inputted to the amplifier 1, for example, the third
The configuration shown in the figure is used. That is, a yw times signal indicating the beginning of information, a radial position detection information DPD signal indicating the radial position of the magnetic medium 1 of the magnetic head 3, and a so-called data signal DRD signal are grouped together at predetermined intervals. It is something that is repeated. Various existing techniques can be considered as formats for modulating these dominant signals and writing them onto the magnetic medium 1, but here, as an example, a format as shown in FIG. 4 is used. That is, in FIG. 4, FL
G is a DC erase signal, and DPD is a binary signal that decreases by 1 from the outer circumference to the inner circumference every time FLG is written.

Therefore, the radial position detection circuit 8 detects the FIfl signal from the input signal in this manner, and selectively detects the subsequent radial position detection information DPD signal, and its output is input to the rotation speed indicating circuit 9. The output of the moving speed detector 6 that detects the moving speed of the actuator 4 is input to the other input terminal of the rotation speed indicating circuit 9 . Rotation speed indication circuit 9
determines the rotation speed to be instructed to the motor 2 based on these two human power signals si and s2, and outputs it to the motor control circuit 10 as an output signal S3.

FIG. 5 is a block diagram showing an example of the configuration of this rotation speed indicating circuit 9. As shown in FIG. In the figure, 11 is a digital-to-analog converter, 12 is an integrator, 13 is an addition circuit, 14 is an arithmetic circuit, 15 is a correction circuit, and 16 is a multiplication circuit.

In the rotation speed indicating circuit having the above configuration, an input signal S1 as radial position detection information and an input signal S2 as moving speed detection information are input to the digital-to-analog converter 11 and the integrator 12, respectively. This digital-to-analog converter 11i1[, . . . outputs a signal changed by level Vl to the adder circuit 13 every time the input signal S1 changes. On the other hand, the integrator 12 continues to integrate the input signal S2 while the input signal S1 maintains the same binary signal, and B1
Addition circuit 13 adds a signal that reaches level v1 just before the change in
Output to. This integrator 12 is instantaneously reset the moment the input signal S1 changes. The adder circuit 13 adds the output signals of the digital-to-analog converter 11 and the integrator 12. With this, the output of the digital-to-analog converter 11, which changes stepwise, can be made into a linear output. The output of this adder circuit 13 is proportional to the radius r of the magnetic medium 1 on which the magnetic head 3 is located.

The arithmetic circuit 14 performs the following arithmetic operation based on the input signal proportional to the radius r mentioned above, and determines the rotational speed such that the relative speed between the magnetic head 3 and the magnetic medium 1 is constant regardless of the half-fir. Outputs a signal indicating N. That is, if the rotational speed at the innermost radius rt of the magnetic medium 1 is Ni, then i N = Ni X- (1). It is well known that such a Hiko calculation function can be easily realized using, for example, a logarithm calculator and an inverse logarithm calculator, or by using the nonlinear characteristics of a diode having a similar principle.

The output of the arithmetic circuit 14 is input to the multiplication circuit 16 together with the output of the correction circuit 15, and the multiplication circuit 16 multiplies both and outputs an output signal S3 as the rotation speed instruction value.

This correction circuit 15 is designed so that when the signal half width 2a of the isolated bit signal shown in FIG. 1 changes depending on the position of the magnetic medium 1, the frequency spectrum of the read multi-signal remains constant regardless of this change. The input signal S1 from the radial position detection circuit 8 is used to indicate the rotation speed.
The following analog value C(r) is output according to the following. That is, as mentioned above, the change in the signal half-width 2a depending on the position is caused by the change in the thickness of the magnetic layer of the magnetic medium 1, and in the case of coated media, this change 2a changes from the inner circumference to the outer circumference as shown in FIG. If the signal half width at the innermost radius is 2ai, then 2a = 2a! x c(r) (however, a(rL)
= 1). Therefore, the correction circuit 15 stores in advance the value of C(r) corresponding to the radial position in its memory, and outputs the c(r) value corresponding to the input r value to the multiplication circuit 16. In FIG. 6, ro indicates the outermost radius. Therefore, at the innermost circumference (r-rt), the output of the correction circuit 15 is 1, and the value of the rotation speed N output by the arithmetic circuit 14 remains unchanged. This is the rotation speed indication value.

In response to the rotation speed instruction signal outputted from the rotation speed instruction circuit 9 in this manner, the motor control circuit 10 outputs a control current to the motor 2 such that the rotation speed becomes equal to this instruction signal. Such a function of the motor control circuit 100 is such that the motor 2 is a Do motor.

In any case, the induction motor is also open loop.

It is well known that a closed AL'-type can be realized in any servo system.

As is well known, the power amplifier 5 receives an analog control signal applied in response to a seek operation or a track follow operation, and outputs it to the actuator 4 in the form of current or voltage.

In this way, considering that the relative velocity between the magnetic medium 1 and the magnetic head 3 and the thickness of the magnetic layer change depending on the radial position of the magnetic medium 1, the magnetic medium By changing the number of revolutions by 10, the frequency spectrum of the read signal can be kept constant.

Note that in the above embodiment, only the case where the radial position of the magnetic head 3 is detected from the signal read from the magnetic medium 1 by the magnetic head 3 has been described, but the present invention is not limited to this. It goes without saying that this radial position detection may be detected, for example, by a detection means provided on the actuator.

As explained above, according to the present invention, the frequency spectrum of the read signal can be made constant regardless of the position on the magnetic medium, so the cutoff frequency and waveform equalization conditions of the low-pass filter of the signal processing circuit are It becomes easy to set so that signal distortion does not occur over the entire area of the medium, and it is possible to suppress the signal reading blindness rate to a low level. Also, by changing the rotation speed in this way,
Since the recording density on the outer circumferential side of the medium can be increased compared to when the number of rotations is constant, it has various excellent effects such as being able to increase the recording capacity in the same recording area.

[Brief explanation of the drawing]

1. I'll is a diagram showing the read waveform of an isolated bit in a digital magnetic storage device, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a diagram showing the signal format of the read signal of the magnetic head. Figure 4 is a diagram showing an example of the signal waveform in Figure 3. Figure 5 is a block diagram showing details of the rotation speed indicating circuit part in Figure 2. Figure 6 is a change in signal half-width. It is a figure which shows an example. DESCRIPTION OF SYMBOLS 1... Magnetic medium, 2... Motor, 3... Magnetic head, 4... Actuator, 6... Speed detector, 8... Radial position detection circuit, 9...・Rotation speed indication circuit, 10...Motor control circuit. Patent Applicant Nippon Telegraph and Telephone Public Corporation Agent Yamakawa

Claims (1)

[Claims] A magnetic medium that records and holds information, a motor that rotates it, and a magnetic head that inputs and outputs information to and from the magnetic medium.
an actuator for moving the magnetic head in the radial direction of the magnetic medium; a speed detection means for detecting the moving speed of the magnetic head in the radial direction; and a radius for detecting the radial position of the magnetic head on the magnetic medium. a position detection means, a rotation speed indicating circuit for indicating the rotation speed of the motor;
a motor control circuit that rotates the motor equal to the instruction of the rotation speed instruction circuit, the rotation speed instruction circuit comprising:
Based on the output of the speed detection means and the output of the radial position detection means, the frequency spectrum of the signal read by the magnetic head from the magnetic medium is constant regardless of the radial position of the magnetic head on the magnetic medium. A magnetic disk device characterized in that the magnetic disk device is configured to calculate a rotation speed such that the rotation speed is calculated and output to the motor control circuit.