JPS5853060A - Position signal detection circuit for sector servo system - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution and to attain off-track compensation of a broad range, by detecting two position signals with one demodulation circuit, and sample-holding a required position signal in response to the position of a head. CONSTITUTION:A sector servo signal demodulation circuit 13 detects two types of sector servo signals based on demodulation gate signals (b), (c) supplied and a difference signal is detected as a position signal. A sample hold circuit 14 sample-holds a position signal being an output (g) of the demodulation circuit 13 as reuired. A demodulation control circuit 18 receives a mark detection signal (a) supplies the gate signals (b), (c) in the specified timing to the demodulation circuit 13. A detection section 15 detects the position of a head 11 based on the position signal (g) and outputs a detection signal (d). The control circuit 18 supplies a sample hold signal (e) based on the output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position signal detection circuit for positioning a head of a magnetic disk device, and relates to a position signal detection circuit for positioning a head of a magnetic disk drive. This invention relates to a position signal detection circuit in a two-phase sector servo system in which side 2 sector servo information is written.

As a head positioning method for magnetic disk drives, there is a sector servo method that uses the servo signal of the servo disk and the sector servo signal written to the data disk. ! This is an effective method for correcting the off-track between the length photo track and the data head that may occur due to various reasons. first sector servo information that generates a position signal;
There is a two-phase sector servo method that uses sector servo information of tIIr2 to generate a linear second position signal near the data track boundary.

From Figures 1 and 2, Kl! I will clarify.

#! In Figure 1, l is a data disk and data sector D
A plurality of servo sectors S are provided spaced apart between each other, and the servo sector SVC has an area 81 in which first sector servo information is written and an area 81 in which second sector servo information 251 is written.
The positional relationship of the trackers in each area is as shown in the figure. When the head is at the Hl position (near the center of the data track), the The position signal S81 of tAl obtained from the sector servo information is linear, and when the head is at the position K of H1 (near the data track boundary), the second position signal 882 obtained from the second sector servo information is linear.

Therefore, when the head is near the center of the data track (in the range of ±]/4 track width from the center of the track) ts * tm
e ts + ty K When Fi first position signal SS+ is used, the head is located near the boundary of the data track (
±l/4 track width from the track boundary) tx
* When at t4+ t@, the second position signal SS,
If the final positioning of the head is carried out using the VC linear position signals S8+ and 88*, the head can always be positioned at any position.

Rank ft! Signal SS+, 881 is the first. This indicates a change in the peak value of the sector servo signal obtained from the second sector servo information, and is detected from the sector servo signal read from each head.

Conventionally, queen detection has been performed by separately providing detection 1Ift for detecting from each @1.82 sector servo signal. and as soon as each is obtained from the detection device 1. The second position signal is switched by a predetermined means and only the necessary signal is used for positioning.

However, in such a detection method, it is necessary to provide exactly the same detection devices, and moreover, they are not used at the same time, which is very wasteful and unrealistic. Furthermore, the switching means is also quite complicated. Therefore, the present invention aims to solve the above-mentioned conventional drawbacks and uses a special glFi of the detection circuit. The first sector servo information that generates a linear first position signal in the vicinity and the second sector servo information that generates a linear 20th position electric signal in the vicinity of the data track boundary are convoluted, and the first In the sector servo method in which the position of the small head is determined based on the second position signal, the first . A sector servo signal demodulation circuit that receives the sector servo signal of the 9J1!1 or second position signal and detects the first or second position signal; 1. The second position signal is sent to the first .
The first, @ for detecting the second position signal, respectively.
2, and a demodulation fIiI control circuit which supplies the mosquito sample hold circuit Kt' sample hold signal in response to the detection signal from the detection section.

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

FIG. 3 is a block diagram showing the detection circuit of this embodiment.
The figure is a signal waveform diagram showing signals a % f of each part for explaining the operation of the detection circuit of FIG. 3.

11Fi data plane data/evening signal and 1st. Second.

The head outputs the 0 sector servo signal and is a 12Fi write/read amplifier. 13 is a sector servo signal circuit which supplies multiple gate signals.

cK: Based on this, the peak value of 2MI[ of the sector servo signal is detected, and the difference signal between them is detected as a position signal. 14 Ifi sample number and hold circuit samples and holds the position signal which is the output of the 101 path 13 when necessary.

17 is an arc detection circuit; The first mark of the sector servo information of @2 is detected and a mark detection signal a is output. 18 is revenge 111i1 f! Il! The control circuit receives the mark detection signal a and sends gate signals S and C at a predetermined timing.
is supplied to the demodulation circuit 13. 15 detects whether the head position is near the center of the data track or near the boundary based on the position signal fK, and flips 70 knob 1.
A detection signal d is outputted via 6. Furthermore, the detection signal dK
Based on this, the demodulation control circuit 18 supplies a sampling hold signal e.

The operation of this embodiment will be explained with reference to FIG.

(1) When the data head is located near the center of the data track (see (+) in FIG. 4) In this case, the demodulation circuit 13 converts the obtained position f1 into the linear first position signal SS. It is necessary to sample and hold the position signal.

The leading mark al of the first sector servo information is detected by the double mark detection circuit 17, and the first gate signal bee is accordingly supplied from the demodulation control circuit 18 to the slide circuit 13. The demodulation circuit 13 has a built-in peak detector which detects two types of peak values of the sector servo signal and calculates the difference between them to detect the first position signal SSt as the output f.

A signal supplied from the output fFi and the mark detection signal a from the demodulation control circuit 18 after a predetermined timing is used as a trigger, and the detection unit 15 compares it with the reference @Ir++r-. At that time, the tree flop I6 is shifted by iK. Here, the reference value r4. When r- is within ±l/4 track width from the track center as shown in FIG.
In other words, it is a value within linear @complete.

Since this output t naturally has a value between r+ and r-, it is detected that the head is near the center of the data track, this information is latched in the flip-flop 16, and the detection signal d
stands up.

In response to the rise of the detection signal d, the control circuit 18 inhibits the output of the second gate signal bee (sample skewer hold signal) and supplies it to the sample hold circuit 14#c. The value of the position signal is held as the position signal f.

(i) When the data head is near the boundary of the data track (see FIG. 4 (ii)) In this case, the signal SS is located at the second linear position A of the position signal obtained from the demodulation circuit 13. It is necessary to sample and hold the signal.

The first position signal is detected by the detection unit 15 as a reference value r+.

The process is similar to the previous example until it is compared with r-.

Therefore, a comparison is made at timing C1, but since the value is not between r++r-, the detection signal dti does not rise.

Next is the second leading mark, Hatake! is detected, now f is [2
The gate signals S and E are supplied to the demodulation circuit 13. Here, the gate signal b + c Fi, the first head mark al
After that, the first gate signal h, the first mark a of father-in-law 2
After , there is a gate signal of W,2.

And 1 on the Pl ladder. The second position signal SS is compared by the detection unit 15 at timing , and since 881 is between r- and r, the head is in data position! It is detected that it is near the boundary of the rack, and a detection signal d rises. The second position signal is sampled and held as a position signal.

As mentioned above, in this embodiment, only one demodulation circuit is provided. The second position signal is detected, and the required position signal is pumped and held depending on the position of the head.

In the present invention, if the position signal is linear after detecting the sector servo information of Ml, the sector servo information of wiJ2 is not detected and is used as the position signal as it is, and if it is outside the 2'-shaped range, the second sector servo position signal is detected. [2′″r position t
Because we use the method of using it as the #Il signal,
It is realized with a simple circuit configuration, requiring only one type of circuit. Revenge! 4. Only the linear portion of each rounded position signal is detected.Since the linear position signal can be used over the entire track, off-track correction can be performed over a wide range, and a great effect can be expected.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a data disk, and FIG. 2 is a top view of a data disk. A waveform diagram showing the relationship between the second position signal and the data track D, FIG. 3 is a block diagram showing an embodiment of the present invention, and a waveform diagram of each part in FIG. In the figure, Iij data disk, DFi data sector, S
is the servo sector, ss, sst is the first servo sector. a second position signal, 13 a sector servo signal demodulation circuit, 14 a sample hold circuit, 15ii detection section, 18 a demodulation control circuit,
b, e are the first or second gate signals, d is the detection signal, e
is the sample and hold signal. Folding II! ]

Claims (1)

[Scope of Claims] All sector servo information that generates a linear first position signal near the data track center in spaced apart servo sectors interposed between the data sectors of the data disk, and a linear second position signal near the data track boundary. and second sector servo information that generates a position signal. The first position signal is read out by the sector servo limb head which positions the head based on the second position signal. A sector servo signal demodulation circuit that receives the second sector servo signal and detects the first or second position signal; # A sample-and-hold (b) path that samples and holds the first or second position signal; 1matasha 2nd
A detection unit for detecting whether the print head is near the center of the data track or near the boundary of the data track based on the position signal of the first one, and a second position signal for the first one. the first and second position signals for respectively detecting the second position signals. a second control circuit that supplies a second gate signal and supplies a sample hold signal to the sample hold circuit in response to a detection signal from the +#9fI section; circuit.