JPH073432B2 - Positioning controller speed detection circuit - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a speed detection circuit for a positioning control device, and more particularly, it can be used for both one-phase and two-phase position signal servo systems, and the positioning control device can be integrated into an IC. Relates to a speed detection circuit suitable for.

(Background of the Invention) An example of a conventional positioning control device for a magnetic disk device is
This will be described with reference to the block diagram of FIG.

On the servo surface 13a of the disk 13, a servo pattern serving as a reference for preliminarily positioning is written. Data head
11, the servo head 12 is mounted on the carriage 10,
These heads are driven by the voice coil motor 4 so as to move to the target cylinder.

The switch 9 is a switch for selecting the seek operation and the following operation, and is connected to the contact 9a during the seek operation and connected to the contact 9b during the following operation. The circuit shown by the broken line is established during the following operation.

During the seek operation, the servo signal is read by the servo head 12, and the position detection circuit 5 is read from the servo signal.
Creates a position signal. This position signal is input to the track cross pulse generation circuit 8, and the circuit 8 outputs a pulse every time the servo head 12 crosses a track. The pulse is supplied to the difference counter 1 and the current position of the head is detected. Further, the difference counter 1 is provided with the target number of cylinders X from the host system. As a result, the difference between the positions of the two is detected, and the speed generation circuit 2 generates a predetermined speed pattern based on this difference.

On the other hand, the output of the power amplifier 3 and the output of the position detection circuit 5 are input to the speed detection circuit 7, and the actual moving speed of the servo head is detected by this. The detected speed is fed back to the adder to form a speed control system.

As a result, the head is speed-controlled according to the speed pattern given to this system and is guided to the target cylinder at high speed.

When the seek operation is finished, the operation moves to the following operation, and the switch 9 is switched to the contact 9b to switch to the position control system. As a result, the head is controlled so that the random relative position error caused by the disturbance becomes zero. The compensating circuit 6 is included in the position control loop for the purpose of enhancing servo rigidity and stability.

By the way, the conventional magnetic disk device positioning device for positioning the read / write head at a target position by using the servo surface servo system by the closed loop uses a one-phase position signal servo system and a two-phase position signal servo system. There is one that uses a system, and either system is selected and adopted according to the type of disk drive. The former system uses one position signal generated as the head moves.
It is disclosed in JP-A-55-97610. In addition, the latter system uses 90% of the phase generated as the head moves.
° Two different position signals are used, for example,
It is disclosed in JP-A-56-157506.

These two servo systems have advantages and disadvantages in positioning accuracy, controllability, and the like. For this reason neither system is not unconditionally will be determined from the good. Therefore, it is preferable to make a device that can be shared by both systems so that the better system can be selected as needed, but no device that realizes this has been proposed in the past.

Further, in the conventional magnetic disk device, the positioning control circuit of the one-phase or two-phase position signal servo system is composed of independent electric parts. Therefore, if both of them are collected, the circuit becomes large and the recent small size. There was a problem that it did not meet the needs of.

(Object of the invention) In view of the above-mentioned conventional technique, an object of the present invention is to provide a speed detection circuit which can be commonly used for a one-phase and two-phase position signal servo system, and thereby to use a positioning control device capable of switching between both servo systems. To provide.

Another object is to provide a speed detection circuit suitable for IC implementation.

(Summary of the Invention) The present invention provides a one-phase position signal servo system and a two-phase position signal servo system in a speed detection circuit of a positioning control device that creates a position signal from a servo head read signal and detects the speed of the servo head from the position signal. It is characterized in that it is equipped with a differential timing control circuit for controlling the differential timing of the position signal, which can be shared by both types of position signal servo systems, so that a servo system suitable for the disk drive can be selected.

(Embodiment of the Invention) The present invention relates to a differential timing control circuit included in a speed detection circuit 7 (see FIG. 4) for speed detection from a position signal, and will be described below with reference to FIGS. hand,
An embodiment of the present invention will be described.

FIG. 1 is a circuit diagram showing a differential timing control circuit which can be commonly used for 1-phase and 2-phase position signal servo systems, and FIG. 2 (a),
FIG. 2B is a time chart of the position signal and the differential timing control signal in the one-phase position signal servo system, and FIG. 3 is a time chart of the position signal and the differential timing control signal in the two-phase position signal servo system.

In FIG. 1, as shown in FIG. 2 (a), 31 is a high level for a non-linear area of a position signal that is greater than or equal to a predetermined threshold Th, and a low level for an area that is less than the threshold Th. Is the signal represented by. Further, reference numeral 32 is a signal in which a non-linear region of the inversion position signal equal to or higher than the threshold Th is represented by a high level and a region of the inversion position signal or less by a low level.

Reference numeral 33 denotes a servo system switching control signal, which is set to a high level when operating in the one-phase position signal servo system and set to a low level when operating in the two-phase position signal servo system. For 35, a low level is selected when seeking in the reverse direction, and a high level is selected when seeking in the forward direction. Reference numeral 40 is a signal which is at a low level when the head detects an even track, and is at a high level when an odd track is detected, and 41 is a signal which becomes a low level during seek and a high level during following.

Reference numeral 22 is a 2 line to 4 line decoder (hereinafter abbreviated as 2 to 4 decoder), which is disabled when the servo system switching control signal 33 is at a high level, that is, when the one-phase position signal servo system is operating. Is at a low level, that is, when the two-phase position signal servo system is operating, it is enabled. The 2-4 decoder 22 operates to output a high level signal to all of its output terminals 0 to 3 when it is disabled. The 2-4 decoder 22 used here decodes one of four output lines 0 to 3 depending on the conditions of binary select 2 input and enable 1 input.

27a and 27b are D-flip-flops, and when a low level signal is input to the preset terminal PR, the input D clock
It is set regardless of the states of the CP and the flip-flop, and is reset when a low level signal is input to the reset terminal R.

The differential timing control circuit of FIG. 1 has EOR gates 21a and 21b.
The 2-4 decoder 22 constitutes a 2-phase differential timing control circuit, and the other circuits constitute a 1-phase differential timing control circuit.

When this circuit is operated in the one-phase position signal servo system, the signal 33 is set to the high level. Then, the NAND gates 26a and 26b become valid (enable state), and the Q signals of the flip-flops 27a and 27b at the previous stage are input to the AND gates 24e and 24f via the NAND gates 26a and 26b, respectively. That is, since the high level output of the 2-4 decoder 22 is input to the AND gates 24e and 24f, the gates 24e and 24f become valid (enable state). Therefore, the output signals of the NAND gates 26a and 26b are the AND gates 24e and 24e.
The signals 36 and 39 are directly transmitted via f.

The signals 36 and 39 are differential timing control signals, which are connected to the switches of the speed detection circuit in the subsequent stage, and the switches are turned on by the low level signals.

When seeking in the forward direction in the one-phase position signal servo system, the signals 36 and 39 are respectively the waveform 36 of FIG. 2 (a), as will be apparent from the description below.
It looks like a and 39a. Therefore, the linear area ▲ ▼ of the position signal is differentiated by the low level of the waveform 36a,
Linear area of inverted position signal at low level of 39a ▲ ▼
By differentiating, the actual moving speed of the servo head can be obtained. In addition, the linear area ▲ ▼ and ▲
In the non-linear region between ▼, the speed can be detected by integrating the output current of the power amplifier.

On the other hand, in the one-phase position signal servo system, when seeking in the reverse direction, the signals 36 and 39 have the waveforms 36b and 39b in FIG. 2A, respectively. Therefore, in this case, the linear area of the inversion position signal
▼ The actual moving speed of the servo head can be detected by differentiating the linear area ▲ ▼ of the position signal.

Next, the operation of the circuit of FIG. 1 when seeking in the forward direction in the one-phase position signal servo system will be described in detail with reference to the time chart of FIG. 2 (b). In addition,
At this time, the signal 41 goes low and the signal 35 goes high.

First, before setting the signal 41 to the low level, the signal 35 is set to the high level to initialize the flip-flops 27a and 27b. As a result, the Q outputs of the flip-flops 27a and 27b are set to high and low levels, respectively.

Next, when the signal 41 is set to the low level, the AND gates 24a and 24c
Is disabled, and AND gates 24b and 24d are enabled. Therefore, the output signals 61, 62, 63 and 64 of the AND gates 24a, 24b, 24c and 24d are all at the low level, as shown in FIG.
The preset and reset status of 27b is released.

Next, when the signal 32 goes high, the output signal 62 of the AND gate 24b goes high, and the flip-flop 27a
Is reset. Therefore, the Q output of the flip-flop 27a becomes low level, and the output signal 36 of the AND gate 24e is changed.
Becomes high level. Further, the signal 32 is inverted by the inverter 23f and input to the clock terminal of the flip-flop 27b, and at the rising edge thereof, the signal input to the D terminal is latched. Therefore, the Q output of the flip-flop 27b becomes high level, and the output signal 39 of the AND gate 24f becomes low level.

Next, when the signal 31 goes high after the signal 32 goes low, the flip-flop 27b is reset,
Its output goes low. The signal 31 is inverted by the inverter 23d and input to the clock terminal of the flip-flop 27a. The flip-flop 27a latches the input signal of the D terminal at the rising edge of the clock and outputs a high level signal from the Q terminal. As a result, the outputs 36 and 39 of the AND gates 24e and 25f become low and high levels, respectively.

When the above operation is repeated, the output signals 36, 39 of the differential timing control circuit of FIG. 1 become the waveforms 36a, 39a of FIG. 2 (a), respectively. In FIG. 2B, the following operation is shown while the seek signal 41 is at the high level.

Next, in the two-phase position signal servo system, the circuit operation of FIG. 1 when seeking in the forward direction will be described with reference to FIG.

Signal 31 is position signal 1 and position signal 2
The signal 32 is a signal in which a non-linear region having a threshold value Th or more (different by 90 °) is set to a high level, and the signal 32 is a signal obtained by delaying the phase of the signal 31 by 90 °.

When seeking in the forward direction, the servo system switching control signal 33 becomes low level, and the 2-4 decoder 22 is enabled. Further, the outputs of the NAND gates 26a and 26b become high level regardless of the signals of the flip-flops 27a and 27b in the previous stage. Therefore, the outputs of the AND gates 24e and 24f become the same level as the output of the 2-4 decoder 22. That is, the output of the 2-4 decoder 22 is the same as the signals 36, 37, 38, 3
It becomes 9 and becomes the switch control signal of the speed detection circuit in the subsequent stage.

Now, when the signals 31 and 32 of FIG. 3 are input to the circuit of FIG. 1, the output signals of the EOR gates 21a and 21b are low level when the signals 31 and 32 are high level, and when the signals 31 and 32 are low level. Become high level. Therefore, the input (A, B) of the 2-4 data 22 is temporally (0,0), (1,0), (1,1), (0,
1) and changes cyclically. As a result, the decoder 2
The output of the 2 output terminals (0,1,2,3) is (0,1,1,1,
1), (1,0,1,1), (1,1,1,0), (1,1,0,1). The timing is as shown in FIG.

Now, assuming that the waveforms of signals 36-39 are 36a-39a respectively,
The linear area ab of the position signal 1 at the low level of the waveform 36a,
The linear region gf of the position signal 2 at the low level of the waveform 37a,
Linear region eh of inverted position signal 2 at low level of waveform 38a
Are differentiated with the low level of the waveform 39a to detect the velocity by differentiating the linear area cd of the inverted position signal 1.

On the other hand, the output signal 36 when seeking in the reverse direction
Assuming that the waveforms of ~ 39 are 36b ~ 39b respectively, this waveform is as shown in Fig. 3, and the linear regions of position signals 1 and 2 and inverted position signals 1 and 2 are differentiated at the low level of these waveforms, respectively, and the actual speed is Is output as.

As described above, in the case of the two-phase position signal servo system, as compared with the one-phase position signal servo system, since there is a continuous straight line portion, accurate speed detection can be performed.

(Effect of the Invention) According to the speed detection circuit of the invention, the actual speed of the head can be detected by either the one-phase servo system or the two-phase servo system by selecting high or low of the servo system switching control signal. . Therefore, there is an effect that one speed detection circuit can be shared by both types.

Further, when the speed detection circuit of the present invention is applied to an IC for positioning control, both types can be made to function with a minimum circuit configuration, and it is possible to increase the added value of functions despite the miniaturization of the circuit. It is extremely effective.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a differential timing control circuit of a one-phase and two-phase position signal servo system according to an embodiment of the present invention, and FIG. 2 is a position signal in the one-phase position signal servo system.
1 is a time chart of the signals of the main parts of the circuit and the differential timing control signal, FIG. 3 is a time chart of the position signal and the differential timing control signal in the two-phase position signal servo system, and FIG. 4 is the positioning of the magnetic disk device. It is an overall block diagram of a control device. 5 ... Position detection circuit, 7 ... Speed detection circuit, 33 ... Servo system switching control signal, 35 ... Reverse signal, 36, 37,
38,39 …… First, second, third, and fourth differential timing control signals

Front page continuation (72) Inventor Toshiyuki Haruna 2880, Kozu, Odawara-shi, Kanagawa Stock company Hitachi Odawara factory (56) References JP-A-56-157506 (JP, A) JP-A-57-26756 (JP) , A) JP-A-55-97610 (JP, A)

Claims (1)

[Claims] 1. A speed detection circuit of a positioning control device which creates a position signal from a servo head read signal and detects the speed of the servo head from the position signal, in a one-phase position signal servo system or a two-phase position signal servo system. Of the servo system switching control signal for selecting one of the two, the differential timing control circuit for controlling the differential timing of the position signal is provided, the differential timing control circuit, the servo system switching control signal The differential timing control circuit of the 1-phase is composed of a 1-phase circuit and a 2-phase circuit for switching between valid and invalid states by the 1-phase position signal and the non-linear area corresponding to the non-linear area of the position signal of the 1-phase. Non-linearity of a first signal having a corresponding second level and an inverted position signal obtained by inverting the position signal. The first level corresponding to the area and the second signal having the second level other than the non-linear area are input, and the linear area corresponding to the linear area having the same direction inclination of the position signal and the inverted position signal is input. The differential timing control signal of a predetermined level is output during the period, and the two-phase differential timing control circuit has a first level and a non-linear region in the non-linear region of the first and second position signals which are 90 ° out of phase with each other. Other than the above, the third signal having the second level and the fourth signal obtained by shifting the phase of the third signal by 90 ° are input, and the first and second position signals and the first and second position signals are input. A differential timing control signal of a predetermined level is output in a period corresponding to a linear region having the same direction inclination of the inversion position signal, and both the one-phase position signal servo system and the two-phase position signal servo system are output. Speed detection circuit of the positioning control apparatus being characterized in that to be able to share the stem.