JPH0321994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a storage device used in electronic computers, peripheral terminal equipment, and the like.

A magnetic disk storage device will be described as an example of a conventional device of this type. In FIG. 1, 1 is a magnetic disk for storing information. 2
3 is a motor shaft, and 3 is a motor that rotates the magnetic disk 1. Reference numeral 4 denotes a servo head for reproducing positional information of the magnetic disk 1 recorded in advance on the magnetic disk 1. A data head 5 records information on the magnetic disk 1 or reproduces information from the magnetic disk 1. 6 is a carriage,
The servo head 4 and data head 5 are moved by a drive mechanism (not shown).
7 is a base, which fixes the motor 3 and supports the carriage 6.
to guide you.

In FIG. 2, numeral 4 indicates a servo head as in FIG.

T _o , T _o+1 , T _o+2 , T _o+3 . . . are servo tracks that are concentrically adjacent to the surface of the magnetic disk 1 facing the servo head 4, as shown by thin arrows B. is pre-magnetized in the circumferential direction. The servo tracks T _o , T _o+1 , T _o+2 , T _o+3 . . . rotate in the direction of the thick arrow A with respect to the servo head 4 . T _o+1/2 , T _o+3/2 , T _o+5/2 ... are servo trucks T _o and T _o+1 , T _o+1 and T _o+2 , T _o+2 and T _{o +3} ... is the boundary.

In Figure 3, D _To+1/2 , D _To+1 , D _To+3/2 ,
D _To+2 ... is the reproduction output of the servo head 4, and the center position of the servo head 4 is the boundary T _o+1/2 , the center of the servo track T _o+1 , the boundary T _o+3/2 ), the servo track
This is the signal at the center of T _o+2 .
EV and OD are the playback output D _To+x of servo head 4 (x=
0, 1, 2, 3...), respectively x = 0, 2,
..., x=1, 3, ... shows the timing of extracting the peak voltage.

In Figure 4, 4 is the same as in Figure 1, and D
is the same as in Figure 3. 8 is the amplifier, 9, 10
is a peak hold circuit, and the timing EV, OD
The peak voltage of the output of amplifier 8 is held.
11 and 12 are integrators, 13 is an adder, and when the servo head 4 moves, the servo tracks T _o+1 ,
Positive at the center of T _o+3 ..., negative at the center of T _o , T _o+2 ..., OV at the boundaries T _o+1/2 , T _o+3/2 , T _o+5/2 ... The voltage outputs a position output +P that continuously occurs in a triangular or sinusoidal waveform as the device moves. 14 is an inverter that outputs a position output -P. 15,1
A comparator 6 inputs the position outputs +P and -P, compares them with a small positive reference voltage, and outputs a digital signal. Comparators 15 and 16 have a slight hysteresis at their inputs. 17 is an OR gate which creates a logical sum of the outputs of comparators 15 and 16 and outputs an output TP.

In Figure 5, +P.TP is the same as in Figure 4,
T _o+1/2 , T _o+1 , T _o+3/2 , T _o+2 ... are shown in Figures 2 and 3.
Same as the figure.

N is noise generated by defects, omissions, unevenness, scratches, etc. on the storage surface of the magnetic disk 1 facing the servo head 4.

Next, the operation will be explained. The playback output D of the servo head 4 corresponds to the position of the servo track T on the magnetic disk 1, and at timings EV and OD _{, x} =0, 2, ..., x=1,
3 are sampled through an amplifier 8 and peak hold circuits 9, 10, respectively, and position outputs +P, -P are obtained by integrators 11, 12, an adder 13, and an inverter 14. Comparator 1
5 and 16 detect the point where the analog signals of position outputs +P and -P pass around 0 volts with a slight hysteresis, and convert it into a digital signal. Therefore, the output TP of the OR gate 17 is near the zero cross point of the position outputs +P and -P, that is, the boundaries of the servo track T T _{o +1/2} , T _{o +3/2} , T _{o +5/2} . . .
Output nearby.

When a positioning command is sent from the electronic computer to the magnetic disk storage device, the carriage 6 is driven by a circuit and drive mechanism (not shown), and the output TP of the OR gate 17, that is, the number of servo tracks T, is counted. When the commanded position is reached, the position output +P or -P OV, that is, the servo track T
The positions of the boundaries T _o+1/2 , T _o+3/2 , T _o+5/2 ... are maintained. Next, when a command to record or reproduce information is sent, the data head 5
Record information on magnetic disk 1 or record information on magnetic disk 1
Play information from.

Since the conventional magnetic disk storage device is configured as described above, if there is a minute defect or the like in the servo track T of the magnetic disk 1, it will be caused by the noise N.
Since the position outputs +P, -P and output TP become error signals and cause positioning errors, it was necessary to inspect the above defects. However, since the defects are minute and the number of servo tracks T is large, manual inspection while visually viewing an oscilloscope requires skill and a great deal of time, making the equipment expensive.
In addition, defects can only be found when the servo head 4 is at the defective position, so it is best to inspect the servo head 4 during normal positioning, especially at the boundaries T _o+1/2 , T _o+3/ of the servo track T. ₂ , T _o+5/2 ... was impossible.

This invention was made in order to eliminate the defects of the conventional device as described above, and it is possible to sufficiently reduce the position output +P obtained from the servo head 4 and the noise N caused by defects in the servo track T superimposed on the position output +P. While comparing the integral signal obtained by integrating the position output +P with a smoothing time constant (for example, magnetic disk 1
The purpose is to automatically inspect the entire servo track T of the magnetic disk 1 in a short period of time by moving the carriage 6 little by little (at a pitch less than the width of the servo head 4 every time the servo head 4 rotates once). There is.

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 6, 4 is the same as in Figures 1, 2, and 4, D, EV, and OD are the same as in Figures 3 and 4, and 8 to 17, -P are as in Figure 4. Same, +P,
TP is the same as in Figure 5. 18 is a DA converter, which is an offset OS for binary digital signals.
is input and outputs an offset output (ΔP) of stepped DC voltage.The offset output ΔP is
This signal is input to a positioning circuit (not shown), and the carriage 6 is moved by an amount corresponding to the offset output ΔP per staircase by the DC voltage. An integrator 19 inputs the position output +P, has a time constant sufficiently larger than the time of the noise N, sufficiently smoothes the noise N, and inputs the output to the comparators 22 and 23. Comparators 22 and 23 have position output +P
The output level of the integrator 19 is compared with the voltage lowered (raised) by the diodes 20 and 21. 24 is an OR gate which creates a logical sum of the outputs of comparators 22 and 23 and outputs a noise signal N' indicating the presence of a defect. By the way, the driving means of the present invention is a DA in the above-mentioned embodiment.
The demodulation means of the present invention is composed of a converter 18, a positioning circuit, and a carriage 6. In one embodiment, the demodulation means includes an amplifier 8, peak hold circuits 9, 10,
The resistance means of the present invention consists of integrators 11, 12 and adder 13, in one embodiment consists of diodes 20 and 21, the integrating means of this invention consists of integrator 19 in one embodiment,
The comparison means of the present invention includes comparators 22 and 23 and an OR gate 24 in one embodiment.

In Figure 7, +P is the same as in Figures 4 to 6;
N is the same as in Figure 5, T _o+1/2 , T _o+1 , T _o+3/2 , T _o+2
... is the same as in Figures 2 and 5, and N' is the same as in Figure 6. R is the time per step of the offset output ΔP.

Next, the operation will be explained. When the offset OS is input to the DA converter 18 in order to inspect the magnetic disk 1, the position output P becomes stepwise because the offset output ΔP moves the carriage 6 by the amount of the offset output ΔP. For example, if the amount of movement of the offset output ΔP is made less than the width of the servo head 4, and the time R is made more than the period of one rotation of the magnetic disk 1, the servo track starts from T _o ,
By moving the carriage 6 sequentially or arbitrarily as T _{o+1/2 ,} T _{o+1 , T o+3/2} , T _o+2 , etc., the entire surface of the magnetic disk 1 facing the servo head 4 is covered. It can be inspected. While the carriage 6 is moving, the comparators 22 and 23 lower (increase) the output level of the integrator 19's smoothed output, which is close to the DC voltage, and the position output +P by the voltage drop of the diodes 20 and 21. To compare voltages, noise N
diodes 20 and 21 are connected to the positive and negative sides of the position output +P.
, the outputs of the comparators 22 and 23 pass through the OR gate 24,
Defects can be easily detected by the noise signal N'. Since the value of the voltage drop across the diodes 20 and 21 is smaller than the hysteresis voltage at the input of the comparators 22 and 23, there is no defect if the noise signal N' is not output. Furthermore, automatic testing is easily possible using the noise signal N'.

In the above embodiments, a magnetic disk storage device is taken as an example, but the present invention can be widely applied to other storage devices such as a recording device, a recording device, a magnetic tape device, and a device that scans a beam such as light or a laser. Further, in the above embodiment, only the storage device was explained, but it may be an inspection device, a servo track writing/reading device, a measuring device, a test device, an entire electronic computer, etc., and the same effect as in the above embodiment can be obtained. play. In addition, in the above embodiment, the offset output ΔP
was created using the DA converter 18, but it may also be created using other circuits within the device or a microprogram. Further, although the voltage drop of the diodes 20 and 21 is used in the above embodiment, other elements such as a resistor may be used.

As described above, according to the present invention, there is a driving means that gradually deviates the position reading head using an offset signal, and a driving means that demodulates the information recorded in advance on the storage medium and reproduced by the position reading head, and demodulating means for outputting a position signal of the storage medium; resistor means for lowering the voltage of the position signal by a predetermined value to output a first voltage; and integrating the position signal with a predetermined time constant to generate a second voltage. an integrating means for outputting an output, and a comparing means for comparing the first and second voltages and outputting a signal indicating that the storage medium is defective when the first voltage is larger than the second voltage. By providing this, it is possible to completely inspect the entire surface of the storage medium for defects on the surface facing the position reading head, and it is also effective in automatically inspecting the surface in a short time and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a side view of a mechanism section showing an example of a conventional magnetic disk storage device, FIG. 2 is a partial view showing an example of a storage surface having position information of a storage medium of a conventional magnetic disk storage device, and FIG. 3 is a waveform diagram showing an example of the reproduced waveform of a conventional position reading head,
FIG. 4 is a block diagram showing an example of a circuit for demodulating a conventional position output, FIG. 5 is a waveform diagram showing an example of a conventional position output, and FIG. 6 is a magnetic disk storage according to an embodiment of the present invention. FIG. 7 is a block diagram of the circuit of the device and a waveform diagram of the device according to an embodiment of the present invention. 1... Magnetic disk, 3... Motor, 4... Servo head, 5... Data head, 6... Carriage, 9, 10... Peak hold circuit, 13...
... Adder, 15, 16, 22, 23 ... Comparator, 17, 24 ... OR gate, 18 ... DA
Converter, 19...Integrator, T...Servo track, D...Reproduction output, +P...Position output, N...
...Noise, N'...Noise signal, ΔP...Offset output. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A driving means for gradually deflecting a position reading head by an offset signal, reproduced by the position reading head,
demodulating means for demodulating information pre-recorded on a storage medium and outputting a position signal of the storage medium; resistance means for lowering the voltage of the position signal by a predetermined value and outputting a first voltage; an integrating means that integrates with a predetermined time constant and outputs a second voltage; and a storage medium that compares the first and second voltages and when the first voltage is greater than the second voltage. 1. A storage device comprising comparison means for outputting a signal indicating that there is a defect in the storage device.