JP2604966B2 - Equal error rate recording method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic storage device,
More particularly, the present invention relates to an equal error rate recording method and apparatus for a magnetic storage device having a plurality of zones having different recording densities.

[0002]

2. Description of the Related Art It is necessary to select an appropriate recording frequency in a magnetic storage device according to the recording density. On the other hand, some magnetic recording devices have a plurality of zones having different recording densities. Therefore, in such a magnetic recording device, it is necessary to set an optimum recording frequency for each zone.

As a conventional recording frequency setting method in this type of apparatus, there has been proposed a method of setting the recording frequency so that the resolution of a reproduced signal is the same in each zone. For example, US Pat. No. 4,799,912 and , JP
It is described in JP-A-63-200306.

In these methods, when setting a recording frequency in a magnetic recording apparatus, writing is performed at an initial setting frequency, and the resolution at that time is measured. If the resolution is higher than the desired value, the recording frequency is further increased. If the desired resolution is not reached, the recording frequency is lowered and rewriting is performed. The recording frequency is set so that

Further, by performing such processing for each zone, the overall recording frequency in the magnetic recording apparatus is determined.

[0006]

As a recent technical trend in a magnetic recording apparatus, a thin film type is often used for a recording / reproducing head.

A thin film type recording / reproducing head is suitable for high-density recording / reproducing. On the other hand, however, one of the drawbacks is a problem that an undershoot is generated in an isolated reproducing waveform, which causes various effects. . In particular, there is a phenomenon that the resolution is affected by the relationship between the position at which the undershoot waveform is generated and the recording frequency, and therefore the resolution itself has little physical significance.

Therefore, in the above-described conventional example, the recording frequency in the magnetic recording apparatus is set on the basis of the resolution, so that not only the optimum recording frequency is not necessarily set but also an inappropriate recording frequency is set. There is a risk that settings will be made.

On the other hand, by performing appropriate waveform processing on the reproduced waveform, the undershoot itself of the isolated reproduced waveform is removed, or the half width of the reproduced waveform is reduced, so that the readout of the magnetic storage device is performed. A method of reducing the error rate at the time is described in, for example,
No. 06 and JP-A-64-27007.

However, a circuit for performing such waveform processing is complicated and not only causes an increase in circuit scale, but also
When the recording frequency changes, there is a problem that it is difficult to respond.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art. In a magnetic recording apparatus having a thin film head, the magnetic recording device is affected by a change in resolution based on an undershoot waveform in the thin film head. Without
You can set the optimal recording frequency,
It is an object of the present invention to provide an equal error rate recording method and apparatus capable of reducing an error rate in each zone so that an error rate is equal in each zone.

[0012]

According to the present invention, the above-mentioned object is achieved by the following means. (1). In a magnetic recording apparatus including a thin-film magnetic head and a magnetic disk having a plurality of zones having different recording densities, a pulse width of a reproduced isolated waveform is detected for each zone, and the detected pulse width is determined. the constant ratio Te and sets the recording frequency.

(2). In this method (1), a fixed ratio
Is K / pulse width, and this value K is close to 2.0.
It is characterized by that.

(3). In the method of (1) or (2), a fixed ratio
After setting the recording frequency by the rate , writing and reading of data are performed while finely adjusting the recording frequency, an error rate is measured for the read data, and the recording frequency is set so that the error rate is minimized. It is characterized by the following.

(4). (1), (2) or (3), wherein a constant of a filter provided in the read channel is set so as to maintain a constant ratio with respect to a pulse width of the reproduced isolated waveform.

(5). A plurality of zones having different recording densities, comprising: a thin-film magnetic head; recording frequency setting means for determining a recording frequency for the recording medium; and writing / reading means for writing to and reading from the recording medium with the recording frequency. In a magnetic recording apparatus that performs writing and reading to and from a magnetic disk, pulse width detection means for detecting a pulse width of an isolated waveform reproduced for each zone is provided, and a recording frequency setting means is provided for each zone. The recording frequency is set at a constant ratio to the width.

(6). The device of (5) is characterized in that the fixed ratio is K / pulse width, and this value K is near 2.0.

(7). Recording frequency setting means for determining a recording frequency for the recording medium, and writing / reading means for writing to and reading from the recording medium with the recording frequency, and for writing to a plurality of zones having different recording densities. In a magnetic recording apparatus for performing reading, a pulse width detecting means for detecting a pulse width of an isolated waveform reproduced for each zone, and an error rate measuring means for measuring an error rate of data read for each zone are provided. After the recording frequency setting means determines the recording frequency for each zone at a fixed ratio with respect to the detected pulse width, writing and reading of data are performed while finely adjusting the recording frequency. Set the recording frequency so that the measured error rate of the read data is the lowest. And butterflies.

(8). In (5), (6) or (7), the constant of the filter 5 provided in the read channel is set so as to maintain a constant ratio with respect to the pulse width detected by the pulse width detecting means 3. Features.

[0020]

[Action] (1). In the equal error rate recording method of the present invention, in a magnetic recording apparatus having a plurality of zones having different recording densities, a pulse width of a reproduced isolated waveform is detected for each zone, and the detected pulse width is determined. The recording frequency is set according to a constant ratio, so when a thin film head is used in a magnetic recording device,
The effect of the undershoot waveform can be eliminated, and an equal error rate recording method of recording an equal error rate in each zone can be realized.

(2). Recording frequency of 2.0 / around pulse width
And

(3). Further, for each zone, the pulse width of the reproduced isolated waveform is detected, the recording frequency is determined by a fixed ratio with respect to the detected pulse width, and then the data is written and read while fine-tuning the recording frequency. To measure the error rate of the read data, and set the recording frequency so that the error rate is minimized. Therefore, when a thin film head is used in a magnetic recording device, an undershoot waveform is generated. In addition, it is possible to quickly and more completely eliminate the influence of the error rate, and to realize an equal error rate recording method for recording an equal error rate in each zone.

(4). In each of the equal error rate recording methods (1), (2) and (3), the constant of the filter provided in the read channel is set so as to maintain a constant ratio to the pulse width of the reproduced isolated waveform. Optimum filter characteristics can be set for the recording frequency.

(5). FIG. 1 shows the basic configuration of the present invention. The magnetic recording apparatus according to the present invention includes a frequency setting means 1 for determining a recording frequency for a recording medium, and a writing / reading means 2 for writing to and reading from the recording medium using the recording frequency. , Writing and reading are performed for a plurality of zones having different recording densities.

In such a magnetic recording apparatus, the pulse width detecting means 3 is provided to detect the pulse width of the isolated waveform reproduced for each zone, and the recording frequency setting means 1 detects the pulse width for each zone. Since the recording frequency is set at a fixed ratio to the pulse width, the effect of the undershoot waveform can be eliminated in a magnetic recording apparatus using a thin film head, and the error rate of each zone can be reduced. It is possible to realize an error rate recording device for performing recording and the like.

(6). Further, in such a magnetic recording apparatus, an error rate measuring means 4 is provided to measure an error rate of data read out for each zone, and the recording frequency setting means 1 outputs the measured error rate for each zone. Since the recording frequency is set so as to minimize the rate, in a magnetic recording apparatus using a thin film head, the influence of an undershoot waveform can be eliminated, and recording at an equal error rate in each zone. An equal error rate recording device can be realized.

(7). Further, in such a magnetic recording apparatus, a pulse width detecting means 3 is provided to detect a pulse width of an isolated waveform reproduced for each zone, and an error rate measuring means 4 is provided to read out a pulse for each zone. The error rate is measured for the data obtained, and the recording frequency setting means 1 determines the recording frequency for each zone at a fixed ratio with respect to the detected pulse width, and then writes the data while fine-tuning the recording frequency. And read, the recording frequency is set so that the error rate measured for the read data is the lowest, so in a magnetic recording device using a thin film head,
The effect of the undershoot waveform can be removed quickly and more completely, and an equal error rate recording device that records an equal error rate in each zone can be realized.

In each of the equal error rate recording devices (5) to (7), the constant of the filter 5 provided in the read channel is maintained at a constant ratio with respect to the pulse width detected by the pulse width detecting means 3. , It is possible to set an optimum filter characteristic for the recording frequency.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a block diagram showing an embodiment of the present invention. In this embodiment, a control circuit 11 for controlling each unit and a synthesizer 12 for generating a write clock from a reference clock in accordance with a given frequency division ratio
An encoder 13 for encoding write data in accordance with a write clock; an R / W (read / write) circuit 14 for writing and reading data; and a magnetic head 15 for writing and reading to and from a recording medium. An amplifier 16 for amplifying the read data, a filter 17 for band limiting the read data, a peak detecting circuit 18 for detecting a peak position in the read data, and a PLO for shaping the read data in synchronization with the write clock. (Phase synchronization circuit) 19 and decoder 20 for decoding shaped data
And pulse width detecting means 21 for detecting the pulse width of the read data.

The synthesizer 12 converts the frequency of the reference clock input according to the frequency division ratio set by the control circuit 11, and generates a write clock corresponding to a required recording frequency. The generated write clock is input to the encoder 13 and the PLO 19.

At the time of writing, the encoder 13 encodes write data into a predetermined code according to a write clock, and inputs the encoded data to the R / W circuit 14 as write data.
The R / W circuit 14 records data on a storage medium (not shown) via the magnetic head 15 by generating a write current according to the write data and supplying the write current to the magnetic head 15.

At the time of reading, the R / W circuit 14 and the amplifier 16 amplify the data read from the magnetic head 15 and input the amplified data to the filter 17 and the pulse width detection circuit 21. The filter 17 has a predetermined cutoff frequency fc and a boost amount set by the control circuit 11, performs waveform operations such as removal of high-frequency noise and pulse slimming, and sends an output signal to the peak detection circuit 18.

The peak detection circuit 18 detects the peak position of the input signal, performs pulsing, and converts the peak pulse into a PLO signal.
Input to 19. The PLO 19 generates a clock synchronized with the peak pulse, resynchronizes the peak pulse with this clock, and inputs the same to the decoder 20 as reference data and a reference clock. The decoder 20 decodes the encoded data based on the reference data and the reference clock, and sends the decoded data to a controller (not shown) as read data.

The pulse width detection circuit 21 detects the pulse width of the amplified reproduction signal from the amplifier 16 and sends the result to the control circuit 11. The control circuit 11 determines the frequency division ratio of the synthesizer 12, P based on the detection result of the pulse width.
The loop filter constant and loop gain of the LO 19, the constant of the filter 17, and the like are calculated, and the constants of the synthesizer 12, the PLO 19, and the filter 17 are set according to the address signal from the controller.

The setting of the recording frequency of the magnetic storage device according to the embodiment shown in FIG. 2 is performed as follows.

First, a solitary wave (low-frequency data that does not cause pattern interference) is written at a predetermined address, and the pulse width of the reproduced solitary wave is detected by the pulse width detection circuit 21. Then, the optimum recording frequency (write clock frequency) is set according to the following equation. Write clock frequency = K / pulse width ...
(1) Here, it is desirable that K is around 2.0 according to the result of the simulation.

From these results, the control circuit 11 controls the oscillation frequency of the synthesizer 12 by setting the frequency division ratio from a reference clock such as a crystal oscillator or a servo clock necessary to obtain a desired recording frequency. .

At the same time, the setting of the loop filter constant and the loop gain of the PLO 19 and the setting of the constant of the filter 17 are also performed. When a booster type filter is used, the setting of the cutoff frequency fc is performed by the following equation. Note that the value of the constant L in the following equation is 0.4 to 0.5.
It is desirable to set to about 5. fc = L / pulse width (2)

In the above description, the one-point address has been described. However, since the magnetic recording apparatus actually has a plurality of addresses, it is necessary to store this information. Each time access is made, each constant is set with reference to this information. The control circuit 11 also has a storage function in this case.

For example, in the case of a magnetic disk device, it is natural that the setting of the recording frequency differs depending on each zone. However, when a plurality of heads are provided, the setting of the recording frequency is changed for each head. There is a need. Therefore, the number of storage areas equal to (the number of zones) × (the number of heads) is required.

In the embodiment shown in FIG. 2, such a storage area is provided in the control circuit 1, but it is not limited to this case, and it goes without saying that a separate memory may be provided. . The storage area may be mounted on an electronic circuit board or an HDA (head disk,
Assembly).

According to the present invention, the effect based on the undershoot waveform of the thin film head can be completely removed, so that the error rate can be reduced.

Next, a method for increasing the effect of the present invention will be described below. In this method, writing and reading of a disk are actually performed, and each constant is set based on the error rate at that time. That is, at a predetermined address, writing and reading are performed while changing the recording frequency, the error rate at that time is measured, and the recording frequency with the lowest error rate is obtained.

Therefore, in the case of this method, the pulse width detection circuit 21 shown in FIG. 2 is unnecessary, and instead,
An error rate measurement result from a controller (not shown) is input to the control circuit 11.

The control circuit 11 calculates the optimum recording frequency from the result, and at the same time, calculates the corresponding loop filter constant and loop gain of the PLO 19 and the constant of the filter 17, and stores the result. In this case, PL
The loop filter constant and loop gain of O19 and the cutoff frequency of the filter 17 can also be calculated from the above-mentioned relational expressions (1) and (2) of the recording frequency and the pulse width.

When the optimum point is obtained at a certain address in this way, subsequently, while changing the address, the optimum point is obtained at each address, and each result is stored.

When data write / read operations are performed, setting information corresponding to a predetermined address is called from the storage area, and the synthesizer 12 and the PLO 1 are accordingly operated.
9. Each constant of the filter 17 is set.

As still another method, a higher effect can be obtained by combining the above two methods. That is, after performing various settings based on the pulse width detection result, similar settings are performed based on the error rate.

If various settings based on the detection result of the pulse width are roughly adjusted, the setting based on the error rate has the meaning of fine adjustment, and the setting based on the detection result of the pulse width is corrected based on the setting result based on the error rate. Take the method of doing. That is, even if only the setting based on the detection result of the pulse width is at a level where there is practically no problem, the optimum point can be obtained by further performing the setting based on the error rate.

As described above, according to the present invention, the influence of the undershoot waveform of the thin film head can be eliminated, and the performance of the magnetic recording head and the magnetic recording medium can be maximized.

[0051]

As described above, according to the present invention, by setting the recording frequency based on the pulse width of the reproduced isolated waveform as a reference, the influence of the undershoot waveform of the thin film head can be completely eliminated. Optimal settings can be made. As a result, the overall error rate can be reduced, and the error rates of the respective zones can be made substantially equal.

Another method is to write and read data in a magnetic storage device, measure the error rate, and set the recording frequency so that the measured error rate is optimized. The effect can be obtained.

As still another method, after setting the recording frequency on the basis of the above-described pulse width, the recording frequency is finely adjusted based on the measurement result of the error rate, whereby the optimum setting can be performed.

According to the present invention, in a magnetic recording apparatus having a plurality of zones having different recording densities, the setting of the recording frequency can be optimized and the performance of the magnetic recording head and the magnetic recording medium can be maximized. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention.

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

[Explanation of symbols]

 1 Recording frequency setting means 2 Writing / reading means 3 Pulse width detecting means 4 Error rate measuring means 5 Filter

Continuation of front page (72) Inventor Osamu Miyazaki 367-2 Sekikan, Sekijo-cho, Makabe-gun, Ibaraki Prefecture Within Ibaraki NEC Corporation (56) References JP-A-63-200306 (JP, A)

Claims (8)

(57) [Claims] In a magnetic recording apparatus comprising a thin-film magnetic head and a magnetic disk having a plurality of zones having different recording densities, a pulse width of a reproduced isolated waveform is detected for each of the zones. An equal error rate recording method, characterized in that the recording frequency is set at a fixed ratio with respect to the set pulse width. 2. The method according to claim 1, wherein the constant ratio is K / pulse width.
The value K is around 2.0.
1. The equal error rate recording method according to 1. 3. After setting a recording frequency by the constant ratio.
In addition, data writing and reading are performed while finely adjusting the recording frequency, an error rate is measured for the read data, and the recording frequency is set so that the error rate is minimized. Claim 1 or 2
Etc. error rate recording method of the placement. 4. The equal error rate recording method according to claim 1, wherein a constant of a filter provided in a read channel is set to maintain a constant ratio with respect to a pulse width of a reproduced isolated waveform. And an error rate recording method. 5. A recording apparatus comprising: a thin-film magnetic head; recording frequency setting means for determining a recording frequency for a recording medium; and writing / reading means for writing to and reading from the recording medium using the recording frequency. In a magnetic recording apparatus that performs writing and reading with respect to a plurality of zones having different densities, a pulse width detecting means for detecting a pulse width of an isolated waveform reproduced for each zone is provided, and the recording frequency setting means is provided for each zone. An equal error rate recording apparatus, wherein a recording frequency is set at a fixed ratio with respect to the detected pulse width. 6. The constant ratio is K / pulse width,
The value K is around 2.0.
5. The equal error rate recording device according to 5. 7. The recording frequency setting means determines a recording frequency for each zone at a fixed ratio with respect to the detected pulse width, and then writes and reads data while finely adjusting the recording frequency. go and claim 5 or the read measured error rate for data and sets the recording frequency to the lowest
6. The equal error rate recording device according to 6 . 8. The filter according to claim 5, wherein a constant of a filter provided in the read channel is set so as to maintain a constant ratio with respect to a pulse width detected by the pulse width detecting means. 7. The equal error rate recording device according to 7.