JPS6357869B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a magnetic disk device, particularly a magnetic disk device having a plurality of recording surfaces, the same recording surface being divided into a plurality of recording areas in the radial direction, and each recording area being separated. The present invention relates to a magnetic disk device accessed by a magnetic head.

(b) Background of the technology Magnetic disk devices are divided into two types: flexible disk devices that use magnetic disks, that is, flexible disks made of synthetic resin coated with magnetic material as recording media, and flexible disk devices that use magnetic material coated on disks such as aluminum alloy. It is roughly divided into hard disk devices that use coated disks, and flexible disk devices are generally divided into 1 type.
In contrast, many hard disk devices include a plurality of magnetic disks.

In order to increase access speed, many hard disk drives divide the same recording surface into multiple recording areas in the radial direction, and each recording area is accessed by a separate magnetic head. The magnetic heads for mutually opposing recording surfaces of the magnetic disk are held by the same access arm.

Therefore, in a magnetic disk device in which two magnetic heads are provided for the same recording surface,
Four magnetic heads are held by one access arm.

FIG. 1 is a diagram showing an example of the configuration of a magnetic disk device provided with four magnetic disks and two magnetic heads on each recording surface, where 1 is a magnetic disk, 2 is a magnetic head, and 3 is a magnetic disk device. An access arm that holds four magnetic heads 2, 4 a carriage that feeds the access arm 3 in the radial direction of the magnetic disk 1 (in the horizontal direction in the figure), and 5 a carriage that holds the four magnetic heads 2 of each access arm 3. In contrast, only one of the four magnetic heads 2 is selected by a magnetic head selection signal generated by a head selection signal circuit 7, which will be described later.
6 is a modulation/demodulation circuit that modulates write data and demodulates read data;
transmits a magnetic head selection signal for selecting one of the four magnetic heads 2 to each of the three magnetic head circuits 5 based on a signal given from a host device (not shown). a circuit selection switching circuit 8 for switching and supplying a magnetic head circuit selection signal to any one of the three magnetic head circuits 5 based on a signal given from the host device; 9 indicates each magnetic head 2 in order to put the magnetic head 2 into write mode.
This is a mode signal generation circuit that generates a write mode signal to be supplied to the magnetic head coil.

When writing data, all the magnetic heads 2 are placed in the write mode by applying a predetermined DC constant voltage from the mode signal generation circuit 9 to the center taps of the magnetic head coils of all the magnetic heads 2. On the other hand, four magnetic head circuits are connected to each of the three magnetic head circuits 5 by the magnetic head selection signal generated by the head selection signal circuit 7 and the magnetic head circuit selection signal generated by the circuit selection switching circuit 8. One of the twelve magnetic heads 2 is selected, and data is written into the corresponding recording area of the magnetic disk 1 via the selected magnetic head 2.

(c) Prior Art and Problems Conventionally, in a magnetic disk device such as the one illustrated in FIG. ,
A predetermined constant DC voltage was being supplied.

Therefore, if the circuit selection switching circuit 8 malfunctions or the signal lines from the circuit selection switching circuit 8 to the three magnetic head circuits 5 are short-circuited, the magnetic head cannot be connected to the two magnetic head circuits 5. When a selection signal is input, two magnetic heads 2 may be selected at the same time, and as a result,
There was a problem in that data was written to a recording area that was not intended for writing, and the data stored on that recording surface was destroyed.

To deal with such problems, measures have been taken to detect such failures using the current flowing through the magnetic head circuit 5, but it is extremely difficult to completely prevent such data destruction. It was difficult.

(d) Purpose of the Invention The purpose of the present invention is to prevent data from being written to other recording areas that are not intended for writing.

(e) Structure of the Invention The magnetic disk device according to the present invention has a plurality of groups of magnetic heads, and a magnetic head selection signal that is commonly provided and input to each of the plurality of magnetic heads in each group of the plurality of groups. a plurality of magnetic head circuits for selecting one of the plurality of magnetic heads for each group; a head selection signal circuit for inputting the magnetic head selection signal to each of the plurality of magnetic head circuits; a circuit selection switching circuit for switching and inputting a magnetic head circuit selection signal to one of the magnetic head circuits; and a write mode supplying the magnetic head coil of each magnetic head to put the magnetic head in a write mode. In a magnetic disk device equipped with a mode signal generation circuit that generates a signal, mode signal switching is performed in which the write mode signal is switched and inputted only to a magnetic head corresponding to a magnetic head circuit to which the magnetic head circuit selection signal is input. The feature is that a circuit is provided.

(f) Examples of the Invention Next, the gist of the present invention will be specifically explained using examples.

FIG. 2 is a block diagram of an embodiment of the present invention.
Symbols common to those in Figure 1 refer to the same objects, and
Reference numeral 10 refers to a write mode signal given as a DC constant voltage generated by the mode signal generation circuit 9, which is sent to a circuit selection switching circuit 8 of the three magnetic head circuits 5 by a signal given from a host device (not shown).
This is a mode signal switching circuit that inputs a magnetic head circuit selection signal only to four magnetic heads 2 corresponding to the magnetic head circuit 5 to which it is input.

With the above configuration, the head selection signal circuit 7 selects one of the three magnetic head circuits 5 for each of the three magnetic head circuits 5 based on the signal given from the host device.
A magnetic head selection signal for selecting the first, second, third, or fourth of each of the four magnetic heads 2 is input, and the circuit selection switching circuit 8 is operated based on the signal given from the host device. Te, 3
A magnetic head circuit selection signal is input to only one of the magnetic head circuits 5.

Further, the write mode signal generated by the mode signal generation circuit 9 is supplied only to the magnetic head 2 corresponding to the magnetic head circuit 5 to which the magnetic head circuit selection signal is inputted by the circuit selection switching circuit 8.

Therefore, due to a failure of the circuit signal switching circuit 8 or a short circuit between the signal lines from the selection signal switching circuit 8 to each magnetic head circuit, the magnetic head selection signal may be sent to the magnetic head circuit 5 unrelated to data writing. Even if data is input, data can be prevented from being written by the magnetic head 2 corresponding to the magnetic head circuit 5.

FIG. 3 shows an example of a specific circuit configuration of the mode signal switching circuit 10. A signal given from a host device is decoded by the decoder 11, and as a result, one of the transistors Tr1, Tr2, or Tr3 is driven. , the DC constant voltage Vst obtained by the mode signal generation circuit 9 generates write mode signals MS1, MS2 only for the four magnetic heads 2 corresponding to any one of the three magnetic head circuits 5.
Or supplied as MS3.

Furthermore, if two or more transistors are driven due to a failure of the decoder 11 or the like and a write mode signal is supplied to the magnetic head 2 corresponding to two or more magnetic head circuits 5, the resistor By comparing the voltage V obtained by the illustrated voltage detection circuit consisting of R.Rd1.Rd2 and Rd3.diode D with the reference voltage Vr, an error signal E is obtained and an abnormality can be detected.

According to the above embodiment, the mode signal switching circuit 10
It is also possible to detect abnormalities in

(g) Effects of the Invention As explained above with reference to the embodiments, according to the present invention, the same recording surface is divided into a plurality of recording areas in the radial direction, and separate magnetic heads can be used. In a magnetic disk device accessed by a user, it is possible to prevent data from being written to other recording areas that are not intended for writing.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional example, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a specific circuit example of a mode signal switching circuit. In these figures, 2 is a magnetic head, 5 is a magnetic head circuit, 7 is a head selection signal circuit, 8 is a circuit selection switching circuit, 9 is a mode signal generation circuit, 1
0 is a mode signal switching circuit.

Claims (1)

[Claims] 1. Select one of the plurality of magnetic heads in each group by means of a plurality of magnetic heads in a plurality of groups and a magnetic head selection signal that is provided and input in common to each of the plurality of magnetic heads in each group of the plurality of groups. a plurality of magnetic head circuits for selecting a magnetic head; a head selection signal circuit for inputting the magnetic head selection signal to each of the plurality of magnetic head circuits; and a head selection signal circuit for inputting the magnetic head selection signal to each of the plurality of magnetic head circuits; A magnetic disk device comprising a circuit selection switching circuit that switches and inputs a head circuit selection signal, and a mode signal generation circuit that generates a write mode signal to be supplied to the magnetic head coil of each magnetic head in order to put the magnetic head in a write mode. A magnetic disk device characterized in that a mode signal switching circuit is provided for switching and inputting the write mode signal only to the magnetic head corresponding to the magnetic head circuit to which the magnetic head circuit selection signal is input.