JPS58177573A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent unnecessary delayed at the generation of a seek end signal, and to shorten the mean access time of a magnetic disk device, by varying a time set for deciding on the completion of seeking operation according to the number of tracks which moves by seeking operation. CONSTITUTION:A timer setting circuit 12 determines the set time of a timer 11 according to the number of tracks found by an address control circuit 4. Namely, when the number of movement tracks in every seeking operation is large, a long set time matching with a settling time at this time is determined and when the number of tracks is small, a short set time matching with the settling time is determined. When an access control circuit 5 sends a timer setting signal to the timer setting circuit 12 right after an access instruction is generated, the timer setting circuit 12 resets the timer 11 and then sets a set time corresponding to the number of movement tracks at this time in the timer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device, and relates to a modification jlLK related to determining the end column of a seek operation in q#.

PRIOR ART In general, a magnetic disk drive determines that the seek operation has ended when the on-track signal generated from the output signal of one servo head during a seek operation continues at a valid level for a set time or more, and transmits the seek end signal to the magnetic disk controller. K is set to send to. In other words, the on-track signal turns on and off during the seeking operation, but once the vibration of the servo head is sufficiently damped by seeking to the target track, the on-track signal stabilizes in the on state (effective level state). This property is used to determine the end of a seek operation.

By the way, conventionally, the above-mentioned set time is determined to be a certain time such that no error occurs under the worst conditions.

In other words, the greater the number of tracks moved during a seek operation, the longer the time (settling time) from seeking to the target track until the servo head's imaging is sufficiently damped (settling time). The settling time during a seek operation that moves by a certain number is fixedly used as the above set time.

However, in reality, the frequency of seek operations under such worst-case conditions is not that high, and most seek operations involve a relatively small number of tracks to be moved. There is an unnecessary idle time after the vibration of the servo head (and therefore the magnetic head corresponding to other data surfaces) is sufficiently damped until the seek end signal is sent. As a result, the average access time increases.

OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic disk drive that reduces the above-mentioned meaningless delay in a sequence signal as much as possible and shortens the average access time.

The fewer tracks moved during a seek operation, the shorter the settling time will be. Therefore, in the present invention, the magnetic disk device is provided with means for changing the set time used to determine the end of a seek operation in accordance with the number of tracks moved for each seek operation. That is, in the present invention, by optimizing the setting time in accordance with the settling time of each individual seek operation, unnecessary delays in the seek end signal are reduced as much as possible.

Embodiment of the Invention FIG. 1 shows the configuration of a portion related to access control of a magnetic disk device according to the present invention.

In the figure, when the magnetic disk device receives an access command and a track address from a magnetic disk control device 1, it stores the track address in a register 2. The address control circuit 4 is activated by an access command, and calculates the number of tracks from the current track to the seek destination track and the moving direction from the track address ° in the register z and the track address of the current track held in the register 8. calculate. The access control circuit 5 is activated by an access command and drives the voice coil motor 7 through the motor drive circuit 6 so as to move the head carriage 20 in the movement direction determined by the address control circuit 4. The moving speed fH of the head carriage 20 is detected by the tachometer 21 and sent to the access control circuit 5.

On the other hand, the output signal of the magnetic head (T-pohendo) 14 corresponding to the servo surface of the magnetic disk 1180 is amplified by the amplifier 8 and then input to the demodulator 9, where a position signal (head position detection signal) 81 is generated. The level detection circuit 10 outputs a track passing pulse signal 8B corresponding to the zero level crossing point of the position signal 81 and a position signal S1.
generates an on-track signal S8 that is turned on (valid level state) during a period in which the signal Vm is within the level range of Vm. The access control circuit 6 counts the number of tracks that the head carriage 80 has moved from the track passage pulse signal 88, and stops driving the voice coil motor when the head carriage 80 has moved by the number of tracks determined by the address control circuit number. In other words, it seeks and positions the track at the track address given by the access command.

Since the process up to this point is exactly the same as a conventional magnetic disk device, further details will be omitted.

13 is a timer setting circuit, which is a characteristic part of the present invention. - This timer setting circuit ls determines the setting time of the timer 11 according to the number of tracks determined by the address control circuit number. In other words, 1. For each seek operation, if the number of tracks moved by the seek operation is large, a long setting time commensurate with the settling time at that time is determined, and if the number of tracks is small, a short setting time commensurate with the interval between IJ songs is determined. Ideally, it would be better to change the set time for each track, but in practice, it is sufficient to change the set time stepwise for multiple tracks.

Now, immediately after the access command is issued, when a timer setting signal is sent from the access control circuit 5 to the timer setting circuit ISa, the timer setting circuit 12 resets the timer 11, and then sets the time according to the number of moving tracks at that time. The timer 111C is set. When the on-track signal S8 remains on for a set time or more, the timer 11 turns on the seek end signal S4 and notifies the magnetic disk control device 1 of the completion of seeking to the target track.

The state of each of the above-mentioned signals 81 to S4 in the seek operation is shown in FIG. 2, and OT in the figure shows the set time of the timer 11. The set time T can be changed depending on the number of tracks to be moved in the seek operation, and this situation is shown in FIGS. 8 to 6.

FIG. 8 shows the case of a seek operation that moves by one track. In this case, when the servo head seeks to the target track, the vibrations of the servo head are attenuated in a short time, so the set time T is determined to be sufficiently short.

FIG. 5 shows the case of a seek operation with a large number of moving tracks. In this case, it can be understood from the waveform of the position signal 810 in the same figure that it takes quite a long time to reach the groove where the vibration of the servo head is sufficiently damped after seeking to the target track. Therefore, the set time T is determined to be sufficiently long.

FIG. 4 shows a seek operation in which the number of moving tracks is intermediate. The setting time T is ta longer than in the case of Fig. 1,
It is determined to be shorter than in the case of FIG.

In addition, the code! -5, 11, and 12 have been described as independent circuits, but it goes without saying that all or part of them may be configured as one circuit. Further, it may be constructed from only these circuit line hardware logics, or may be constructed from a combination of hardware logic and microprogram logic. Regardless of which configuration method you choose, if you are an engineer with average technical knowledge in the relevant technical field,
Since these circuits can be easily implemented using known techniques, no further details will be given.

Effects of the Invention As is clear from the above description, according to the present invention, by changing the time set for determining the end of a seek operation in accordance with the number of tracks moved by the seek operation,
This prevents unnecessary delays in the sequence end signal generation time.
As a result, the effect of shortening the average access time of the magnetic disk device can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the status of each signal during a seek operation in the same embodiment, and Figs. 8 to 6 are diagrams showing the number of moving strokes and set time. It is a rounding diagram explaining Sekiho. l...Magnetic disk control unit 42.8...Register,
4... Address control circuit, 5... Access control circuit, 6... Motor drive circuit, 7... Voice coil motor, 8... l/1mm, 9... Demo simulator, 1
0- Level detection circuit, 11... Timer, 12...
・Timer setting circuit, 20...head carriage, 9
4... Servo head, 81... Position signal, 8
8... On-track signal, S4... Sequence end signal.

Claims (1)

[Claims] (1) A configuration that determines that the seek operation has ended if the time period during which the output signal of the magnetic head corresponding to one sabot surface or a specific signal related thereto continues in a specific state during a seek operation exceeds a set time. A magnetic disk device, characterized in that the magnetic disk device comprises means for changing the set time according to the number of tracks from a track position immediately before starting a seek operation to a track position to be sought in the seek operation.