JPS5836431B2 - head control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a magnetic head, and more particularly to a head control device that can reliably move the head to a magnetic disk or the like.

FIG. 1 shows an embodiment of the present invention, in which CPU is an arithmetic control unit, DC is a control circuit for discriminating commands from the CPU, etc., A1 is a specified head address storage circuit for moving the head to a target position, A2 is a current head address storage circuit that stores the current position of the head, C is a circuit that compares the position information of AI and A2, SC is a circuit that receives the output of C and controls the moving direction of the head, and HD is SC a drive circuit that moves the head in an appropriate direction by the output of D;
is a magnetic disk, W is a circuit that controls writing to D, R is D
This is a circuit that controls reading from.

Now, assume that the head H is located at the 15th track on the magnetic disk D as shown in the second figure.

It is also assumed that the current head address storage circuit A2 stores correct position information 15 for the head H.

At this time, when a write command including head address information (for example, 8 tracks) is output from the CPU, the control circuit DC determines this and the specified head address storage circuit A
Store 8 in 1.

The current head position is track 15, and the comparator circuit C detects the difference and operates the moving direction control circuit SC and head drive circuit HD to move the head H to the 8th track.

At the same time, the contents of the current head address storage circuit A2 (
Subtract 1 from 15).

When the content becomes 8, the comparison circuit C detects a match,
The head H is stopped by stopping the movement direction control circuit.
If the movement of the head is stopped, the head will be located at the 8th track.

Further, this coincidence output is applied to the control circuit DC, and since it has been determined that the previous command is a write command, the write circuit MW is activated to write the predetermined information from the CPU to the 8th track.

In the above-mentioned operation, there is no causal relationship between the specific movement work of the head H and the subtraction operation of the current head address storage circuit A2, so conventionally, cases often occur where the position after the head movement and the contents of A2 do not match. did.

In order to solve this problem, the present invention does not start a write operation immediately after the comparator circuit C detects a match, but once confirms the current head position, and performs a specific write operation etc. only when the head position is certainly correct. It is structured so that you can move on to your work.

That is, if the comparison circuit C detects a match, the read circuit R is activated before the write circuit W is activated.
The read circuit R reads the track position information provided on the magnetic disk by the head H and stores the current head address storage circuit A2.
to be memorized.

Here, the coincidence detection operation is performed again.

If the head movement operation is performed correctly, the number of tracks 8 is stored again in the current head address storage circuit A2, and
The matching output from the corrected comparison circuit C is also sent to the control circuit DC.
3 control circuit DC, which is sent out, stops the operation of the readout circuit R when it detects a coincidence output after the readout circuit R is activated.

Also, the write circuit W is activated to write predetermined information.

If the head movement is not performed correctly and the movement operation stops at, for example, the 10th track, track information 10 is stored in the current head address storage circuit A2.

The specified address is 8, and the contents of 8 and 10 are stored in A1 and A2, respectively, so as mentioned above, the moving direction control circuit S
When C is activated again and the head H is moved by two more tracks, a coincidence output is sent from the comparator circuit C to the control circuit DC, and as mentioned above, the coincidence output after activation of the readout circuit R is taken as the final correct coincidence output. After making a determination, a specific operation such as a write operation is performed as described above.

Since the present invention enables head addressing to be performed reliably as described above, it is possible to easily perform high-speed movement of the head, advance movement, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a perspective view of a magnetic disk. D...Magnetic disk, H...Head, HD
...Head drive circuit, R...Read circuit, W...Write circuit, A1...Specified head address storage circuit, A2...Currently Head address storage circuit, SC: movement direction control circuit, C: comparison circuit, DC: control circuit.

Claims (1)

[Claims] 1. A head for recording or reproducing information on a predetermined track position of a magnetic disk, a specified head address storage circuit for moving the head to a target position, and a current head address for storing the current position of the head. a storage circuit; a comparison circuit that compares position information of the specified head address storage circuit with position information of the current head address storage circuit;
a movement direction control circuit that receives the output of the comparison circuit and the output of the current head address storage circuit and changes the value stored in the current head address storage circuit; and a movement direction control circuit that receives the output of the movement direction control circuit and drives the head. When the head drive circuit that moves the head by moving the head, the write circuit that controls writing of the head to the magnetic disk, the read circuit that controls the read of the head from the magnetic disk, and the comparison circuit detect coincidence of positional information. a control circuit that causes the current head address storage circuit to store the track position information read by the readout circuit, stops the operation of the readout circuit, and activates the write circuit based on coincidence detection output from the comparison circuit again; A head control device comprising: