JPH0321995B2 - - 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 is a motor shaft, and 3 is a motor, which 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. 5
is a data head which records information on the magnetic disk 1 or reproduces information from the magnetic disk 1. A carriage 6 moves the servo head 4 and data head 5 by a drive mechanism (not shown). A base 7 fixes the motor 3 and guides the carriage 6.

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 reproduction output (D _To +x) (x = 0, 1, 2, 3...) of the servo head 4,
The timing for extracting the peak voltages for x=0, 2, . . . , x= 1, 3, . . . is shown, respectively.

In FIG. 4, 4 is the same as in FIGS. 1 and 2, and D is the same as in FIG. 3. 8 is an amplifier, 9 and 10 are peak hold circuits, timing (EV),
(OD) holds the peak voltage of the output of amplifier 8. 11 and 12 are integrators, 13 is an adder, and when the servo head 4 moves, the servo track
Positive at the center of T _o+1 , T _o+3 ..., negative at the center of T _o , T _o+2 , boundaries T _o+1/2 , T _o+3/2 , T _o+5/2 …then OV
The voltage outputs a position output (+P) that continuously occurs in the form of a triangular wave or a sine wave as the motor moves.
14 is an inverter that outputs a position output (-P). 15 and 16 are comparators, position output +
It inputs P and -P, compares them with a small positive reference voltage, and outputs a digital signal. Comparator 1
5 and 16 have a slight hysteresis in their inputs. 17 is an OR gate that creates the logical sum of the outputs of comparators 15 and 16 and outputs (TP)
Output.

In Figure 5, +P and TP are 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 reproduction output D of the servo head 4 has timings (EV) and (OD) corresponding to the position of the servo track T of the magnetic disk 1.
So x=0, 2,..., x= of servo track T _o+x
The peak voltages of 1, 3... are sampled through the amplifier 8 and peak hold circuits 9, 10, respectively,
Integrators 11 and 12, adder 13, and inverter 14
The position outputs +P and -P are obtained by . Comparators 15 and 16 detect, with slight hysteresis, the point at which the analog signals of position outputs +P and -P pass near 0 volts, and convert it into a digital signal. Therefore, the output TP of the OR gate 17 is
Near the zero cross point of position output +P, -P, that is, the boundary of servo track T T _{o +1/2} , T _{o +3/2} ,
Output near T _o+5/2 ...

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,
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, inspection by a person while visually viewing an oscilloscope requires skill and a large amount 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 especially important to inspect the servo track T while performing normal positioning.
It was impossible near the boundaries of T _o+1/2 , T _o+3/2 , T _o+5/2 ....

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it uses a voltage obtained by adding an offset voltage to the position output +P obtained from the servo head 4 and a defect in the servo track T. By moving the carriage 6 little by little (for example, at a pitch equal to or less than the width of the servo head 4 every time the magnetic disk 1 rotates once), the magnetic It is an object of the present invention to provide a magnetic disk storage device capable of inspecting the entire servo track T of a disk 1 without omission.

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 as +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 a stepped voltage (Px), and the deviation corresponding to the voltage (Px) is
give to That is, after the carriage 6 reaches the commanded position, the position of the carriage 6 is moved while the position output +P or -P remains at OV. Comparators 19 and 20 compare the position output +P while maintaining OV with the reference voltages +V and -V. 2 is an OR gate which creates a logical sum of the outputs of the comparators 19 and 20 and outputs a noise signal N' indicating the presence of a defect.

By the way, the addition means of the present invention is composed of the adder 13 in the above-mentioned embodiment, and the comparison means of the present invention is composed of the comparators 19 and 2 in the embodiment.
0 and an OR gate 21.

In Figure 7, +P is the same as Figures 4 to 6, N
are the same as in Figure 5, T _o+1/2 , T _o+1 , T _o+3/2 , T _o+2 ...
are the same as in Figures 2 and 5, and N' and Px are the same as in Figure 6. R is the time per step of voltage (Px).

Next, the operation will be explained. In order to inspect the magnetic disk 1, when an offset (OS) is input to the DA converter 18, the voltage (Px) shifts and moves the position of the carriage 6 in a stepwise manner. For example, the amount of one-step movement of the voltage (Px) is set to be less than or equal to the width of the servo head 4, and the time (R) is set to the width of the magnetic disk 1.
According to the period of one revolution or more, the servo truck
deviate from T _o+1/2 to around T _o+1 , further tighten to T _o+3/2 , then position at T _o+1/2 as before, then T _o+1 The entire surface of the magnetic disk 1 facing the servo head 4 is inspected by deviating from the vicinity to around T _{o +2} , then returning to T _{o +3/2} , and continuing the operation of positioning again. I can do things. While the carriage 6 is moving, the comparators 19 and 20 output the position output + while maintaining the OV, except for a minute voltage that occurs because the carriage 6 is slightly delayed in response when the voltage (Px) step changes.
P and the reference voltages +V, -V are compared, and when the noise N is superimposed on the position output +P to be more than the reference voltages +V, -V, the outputs of the comparators 19 and 20 pass through the OR gate 21, and the noise signal N' Defects can be easily detected. Since the values of the reference voltages +V and -V are smaller than the hysteresis voltages of the inputs of the comparators 15 and 16, the noise signal
If N′ is not output, there is no defect. moreover,
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 effects as in the above embodiment can be obtained. play. In the above embodiment, the voltage (Px) is generated by the DA converter 18, but other circuits in the device,
It can also be created using a microprogram.

As described above, according to the present invention, the voltage that causes the deviation of the position is determined by comparing the voltage obtained by adding the voltage that causes the position deviation to the position signal of the storage medium and the reference voltage that is smaller than the noise generated by the defect in the medium. By moving the position reading head little by little, 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 drawings]

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 signal, FIG. 5 is a waveform diagram showing an example of a conventional position signal, 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, 19, 20 ... Comparator, 17, 21 ... OR gate, 18 ... DA
Converter, T...Servo track, D...Reproduction output, +P...Position output, N...Noise, N'...Noise signal, Px...Voltage In the figures, the same symbols are the same or equivalent parts shows.

Claims (1)

[Scope of Claims] 1. Adding means for adding a position signal of a storage medium obtained by reproducing and demodulating information pre-recorded on a storage medium, and a voltage for shifting the position to this position signal; and a comparison means for comparing the output with a predetermined reference voltage and outputting a signal indicating a defect in the storage medium when the output of the adding means is larger than the predetermined reference voltage; and a position used for reproducing the information. A storage device characterized in that the comparing means compares the output of the adding means with a predetermined reference voltage while gradually deviating the read head by changing the voltage for deviating the position.