JPS6128851A - Method for measuring temperature and humidity expansion ratios of flexible magnetic disc - Google Patents

Abstract

PURPOSE:To measure a disc to be measured within a short time without moving said disc from a measuring environment, by measuring off-track amounts at a plurality of points on one round of a track under environments different in temp. or humidity and calculating the difference thereof to perform operation processing. CONSTITUTION:After the signal of a disc 1 to be measured is regenerated and amplified by an amplifier 3, the amplified signal is subjected to DC conversion by an AC-AD converter circuit 4 while reacted only with a label mark recorded so as to be differentiated from a burst data block in recording frequency by a label mark detection circuit 5 to generate a pulse signal. When the measuring switch of an input apparatus 8 is pushed, an A/D conversion starting signal is sent to an A/D converter 6 and this A/D converter 6 converts the pulse output signal of the label mark detection circuit 5 to a trigger signal to continuously sample the output of the converter circuit 4 during one rotation of the disc 1 and data is transmitted to a microcomputer system apparatus 7 and operation is performed on the basis of this data to measure an off-track amount.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for measuring temperature and humidity expansion coefficients of flexible magnetic disks (hereinafter referred to as disks) used in magnetic disk drives.

Conventional configuration and its problems Disks used in disk devices have multiple recording tracks, and in order to maintain compatibility between disk devices and improve device reliability, the off-track amount of the magnetic head must be adjusted to a certain level. It is necessary to keep it below a certain amount. This off-track occurs largely due to the TiSF device, but expansion and contraction of the disk due to changes in temperature and humidity are also factors that cannot be ignored.

One method for measuring the expansion of a disk due to temperature or humidity is to mark a measurement point on the disk and precisely measure the position using a microscope or the like to determine changes due to expansion. However, in this conventional example, in order to measure the position of a measurement point on the disk, the disk must be left in a certain environment for a certain period of time and then moved to a place such as a microscope, and the position of multiple measurement points must be measured. This has the problem that measurement conditions change because it takes time.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for measuring the temperature and humidity expansion coefficient of a disk, which makes it possible to measure the expansion coefficient of a disk due to changes in temperature or humidity without moving the disk to be measured from the measurement environment. That's true.

Structure of the Invention The method for measuring temperature and humidity expansion coefficient of a flexible magnetic disk of the present invention is to measure the amount of deviation of a magnetic head from a predetermined track center at a predetermined track position, that is, the off-track amount, by 1 - one round of the rack under different temperature or humidity environments. The system is configured to measure the temperature or humidity expansion coefficient of the flexible magnetic disk by measuring at multiple points above and determining the amount of change in off-track amount at each measurement point under different environments. It is possible to measure the temperature or humidity expansion coefficient in a short time without moving the sensor.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a pattern recorded on a disk to be measured and its reproduced signal waveform in an embodiment of the temperature/humidity expansion coefficient measuring method of the present invention. In Figure 1, x is a marker mark to indicate the starting point of the trunk.
Recording is performed centering on the track center of a predetermined track j. Data blocks D to D4 are burst-shaped data blocks for measuring off-track amount, and are recorded alternately over tracks in the inner and outer circumferential directions of the disk, with the track center N of a predetermined track as the border. In addition, the indicator mark Ix and the data blocks D1 to D4
The signal recording frequency is different. Further, Rw in FIG. 1 indicates the gap width of the reproducing head H for reproducing these data. Figure 1 (1a) shows the playback head H.
(1b)
) is a diagram showing the output waveform in that state. On the other hand, FIG. 1(2a) is a diagram showing a state in which the reproducing head H is off-track by about 174 head widths toward the inner circumferential side of the disk, and FIG. 1(2b) is a diagram showing the output waveform in that state.

D□ and D2 in Figure 1. D3 and D9, . . . form a pair, and the relative values of the output levels of these data (E, E,
. ) changes. That is, if the playback head H is completely on-track as shown in FIG. 1 (1a), the playback head H will play back the inner block and the outer block by the same width, so the output level will be lower. The relative value of is shown in Figure 1 (
1b). However, if the playback head H is off-track to any of the four sides, the block on the off-track side is played back more widely as shown in Figure 1 (2a), so the relative value of the output level is shown in Figure 1 (
As shown in 2b), the block on the off-track side is larger. Therefore, this relative ratio of output levels corresponds to the amount of off-track, and it becomes possible to measure the amount of off-track in each data block during the track.

The marker mark × is recorded at only one place during the track lap, so the marker mark 1. to next sign mark Ix
The period up to this point is the track-circumference, and the amount of off-track at multiple points can be measured during this period.

Figure 2 shows that the temperature is T1 and 'r2 (T2>Tt, the humidity is H
1) shows an example of a change in the amount of off-track at each measurement point. Using a disk on which N sets (12 sets in the example of Fig. 2) of data blocks are recorded on the track circumference, the amount of off-track at each measurement point at temperature T1 and humidity H1 is axi (i = 1 to N). Next, after changing only the temperature to T2 (T2>T□) and leaving it for a certain period of time, the off-track amount was 82□ (i = 1
~N). At this time, the disk expands, but since the reproducing head is fixed, the off-track moves relatively toward the inner circumference. Therefore, the amount of change in off-track amount at each measurement point Δal” axi azi (1=
1 to N) indicate the amount of expansion due to temperature change of the disk at each measurement point. Further, when the temperature is kept constant and the humidity is changed from H1 to Hx (Hx>Ht), the amount of expansion due to humidity can be obtained. This is the principle of the method for measuring the temperature and one-degree expansion coefficient of a disk according to the present invention.

It goes without saying that during this measurement, the position of the reproducing head should not change even if the temperature and humidity change.

What has been explained above is the measurement principle of the present invention.

Since the measured off-track amount includes an eccentric component of the disk drive device and the disk, it does not strictly indicate an accurate amount of expansion. In the embodiment, in order to remove this eccentric component, the data of the amount of off-track variation over the track is Fourier-transformed and decomposed into frequency components. In other words, since the eccentric component is a fluctuation with one period of disk rotation, the first harmonic component of the Fourier transformed data is the eccentric component, while the DC component is the fluctuation of the temperature.
Or it is a component of expansion caused by humidity. Further, by similarly extracting the second harmonic component, the expansion change component due to the anisotropy of the disk can be determined.

FIG. 3 is a block diagram showing the structure of an embodiment of the temperature and humidity expansion coefficient measuring method according to the present invention.

In FIG. 3, (1) is a disk to be measured on which a pattern for measuring off-track amount as shown in FIG. 1 is written;
(2) is a playback head, (3) is an amplifier that amplifies the disk playback output signal to an appropriate level, (4) is an AC-DC conversion circuit that converts the AC playback signal to DC, (
5) is a marker detection circuit for detecting the marker mark recorded on the disk (1), and (6) is an AC-DC converter circuit (4) that converts the analog signal converted into DC into a digital quantity. (7) is a microcomputer system device (hereinafter abbreviated as microcomputer) that calculates the expansion rate by calculating the data taken in from the A/D converter and controls peripheral devices. Reference numeral 8) is an input device for inputting environmental conditions necessary for calculations and instructions for starting measurement, etc., and reference numeral 9 is a display device for displaying the results.

The operation of this embodiment configured in this manner will be described below. A weak reproduction signal reproduced from the disk under test (1) by the reproduction head (2) is amplified to an appropriate level by the amplifier (3).

The AC-DC conversion circuit (4) is a kind of envelope detector, and converts the AC reproduction signal into DC. The indicator mark detection circuit (5) generates a pulse signal in response to only the indicator mark x recorded at a different recording frequency from that of the burst data block. When the measurement start switch of the input device (8) is pressed, the microcomputer (7) starts the A/
A signal to start A/D conversion is sent to the D converter (6). A
When the /D converter (6) receives the A/D conversion start signal, it is triggered by the pulse output signal of the indicator mark detection circuit (5) and performs AC-DC conversion M (4 times) during one rotation of the disk.
) is continuously sampled and the data is transferred to the microcomputer (7). Since the position where the data block is recorded on the disk (1) is fixed, the microcomputer (7) can extract the data of the data block from the data that has been continuously A/D converted, and this data Calculation is performed using , and the amount of off-track is determined. Perform the above operation under another environment to measure the amount of off-track, find the difference in the amount of off-track for each measurement point as explained earlier, and perform Fourier transform on one revolution of the disk to decompose it into frequency components. and measure the temperature or humidity expansion coefficient of the disk. Note that all measurement results etc. are displayed on the display device (9).

The present embodiment described above will be explained again one by one. As shown in the flowchart of FIG. 4, first, in step (2), the measurement conditions in the initial environment are input, and then, in step (2), the amount of off-track is measured. Step■
After changing the measurement environment in step (2), input the measurement conditions in step (2), and measure the off-track amount again in step (2). next,
In step (2), the amount of off-track obtained in step (2) and the amount of off-track obtained in step (2) are obtained at each measurement point, and in step (2), Fourier transform is performed for one revolution of the disk to decompose it into frequency components.

At this time, the DC component represents the amount of expansion, the linear component represents the amount of eccentricity, and the 2nd order component represents the amount of eccentricity.
The next components each represent the amount of expansion due to the anisotropy of the disk. Then, the expansion rate is determined by dividing the amount of expansion by the temperature difference or humidity difference, and the results obtained in the above steps are displayed on the display device in step (2).

As described above, according to this embodiment, the off-track amount is measured under environments with different temperatures or humidity, and the difference is calculated and processed, thereby measuring the expansion rate of the disk due to changes in temperature or humidity. It has been realized.

Effects of the Invention As is clear from the above description, the present invention measures the off-track amount of a magnetic head at a predetermined track position at multiple points on one track circumference under different temperature or humidity environments, and calculates the off-track amount at each measurement point. Since the configuration is configured to determine the temperature or humidity expansion coefficient of the disk rather than determining the amount of change, the measurement can be performed without moving the disk to be measured from the measurement environment.
An excellent effect is obtained in that the temperature or humidity expansion coefficient of the disk can be measured.

[Brief explanation of drawings]

Figure 1 shows the pattern for measuring off-track amount recorded on the disk under test. (la) and (lb) are schematic diagrams and reproduced waveforms when the data block and the playback head are completely on-track. Figures 2a and 2b are schematic diagrams and reproduction waveform diagrams of the state in which the reproducing head is off-tracking toward the inner circumference, and Figure 2 is the change in off-track amount at each measurement point when the temperature is changed. A characteristic diagram showing an example, FIG.
WJ*t****dQ(1) @4'F-@:WMAJ
. This is a flowchart for (I x)... indicator mark, (Dl) ~ (D2)...
・Data block, (H)...Playback head, (1)・
・・Disk to be measured, (2) ・・Playback head, (4)
... AC-DC conversion circuit, (5) ... Sign mark detection circuit, (6) ... A/D converter, (7) ... Microcomputer system device agent Morimoto
Yoshihiro Figure 1 Female Figure 4 λ Telf 0

Claims (1)

[Claims] 1. The amount of deviation of the magnetic head from a predetermined track center at a predetermined track position, that is, the amount of off-track, is measured at multiple points around the track under different temperature or humidity environments, and each A method for measuring the temperature and humidity expansion coefficient of a flexible magnetic disk, which measures the temperature or humidity expansion coefficient of the flexible magnetic disk by determining the amount of change in the amount of off-track at a measurement point. 2. Regarding the measurement of off-track amount, at least two burst-like data blocks are arranged alternately in the outer and inner circumferential directions of the disk with the track center at a predetermined track position as the border.
A method for measuring temperature and humidity expansion coefficient of a flexible magnetic disk according to claim 1, characterized in that a flexible magnetic disk on which at least one set of data is recorded is used. 3. Regarding the temperature and humidity expansion coefficient measurement of the disk, the data of the measured off-track amount is Fourier transformed for one revolution of the disk, and only the direct current component which is the expansion component is extracted. The method for measuring the temperature and humidity expansion coefficient of a flexible magnetic disk.