JPH10320782A - Position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and accurately detect a position of an object to be controlled without complicating the constitution of the device. SOLUTION: A track error signal A and a track signal B in sine waves are observed from a sensor in accordance with movement of a head. The position and the speed of the head are detected by a position detector 2 based on signals DA and DB obtained by binarizing the signals A and B with binarizers 1A and 1B, and the detected values are read out by a processor 7. That is, binary signals QA and QB corrected in a waveform correction circuit 3 are inputted together with signals ZA and ZB latched by D-type flip-flops 4A and 4B to a logic circuit 5 to output a count signal and its direction signal onto output lines 8 and 9, and these signals are coded as a position and a speed by an up-down counter timer 6. The speed is obtained by measuring a pulse width, i.e., a time between its edges by the timer 6 and making an inverse number of this pulse width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention binarizes a one-phase or two-phase sensor output signal detected in accordance with the movement of a controlled object, and based on the binarized signal, controls the controlled object. The present invention relates to a position detecting device for detecting a moving amount and / or a moving speed of a moving object. More specifically, the present invention relates to a position detecting device suitable for various position controls such as a track position control of a head on a magnetic disk or an optical disk.

[0002]

2. Description of the Related Art In a generally known magnetic disk drive or optical disk drive, a track error signal that changes in a sinusoidal manner is generated every time a head crosses a track on a disk, and a pulse signal obtained by binarizing the signal is generated. The track position of the head is detected by counting the signals. In addition, the speed of the head is detected by measuring the period. However, this track error signal is disturbed by the influence of sector marks, noise, stains on the disk surface, and the like, and errors may occur in position and speed detection.

FIG. 3 shows a specific example in which a track count is incorrect when a conventional magneto-optical disk drive is used. That is, due to the influence of the sector mark of the magneto-optical disk, a short pulse noise is generated mainly at the time of low speed as shown in FIG. As shown in 2), a phenomenon occurs in which a pulse is lost and counting is reduced by one track. As a result, accurate position and speed information cannot be obtained, which is a factor that degrades controllability such as access speed and stability.

To solve such a problem, it is conceivable to apply a PLL (Phase Locked Loop) circuit using a VCO (Voltage Controlled Oscillator) to correct the disturbance of the track error signal in a specific high frequency range. .

As a conventional technique for addressing such a problem, an expected position and an allowable fluctuation range of the next pulse edge are set based on the immediately preceding pulse cycle. In Japanese Patent Application Laid-Open No. Hei 4-291025, a pulse is generated at an expected position and the pulse is corrected.

Further, when the head is sought and stopped on a target track, the moving direction cannot be determined only by the track error signal. As a means for preventing this, there is known a method of judging a moving direction of a track by using a track error signal and a signal whose phase is shifted by 90 degrees (hereinafter referred to as a track signal).

[0007]

However, in correcting the track error signal of the disk drive device, it is difficult to obtain ideal synchronization and correction characteristics over a wide frequency range by the former method using a PLL circuit.
The applicable frequency variation range is limited to a narrow range (for example, 250 kHz to 1 MHz) about several times higher than the high frequency, and is not practically sufficient.

In the latter method described in Japanese Patent Laid-Open Publication No. Hei 4-291025, if there is no edge within an allowable range centered on the expected position given by the immediately preceding pulse width, a pulse is output to the expected position. However, in order to achieve this, the output of the entire corrected signal must be delayed by the permissible time, which degrades controllability and deviates slightly from the permissible range. If there is an input, the pulse is corrected to the expected position, and there is a problem that there is a high risk of causing a synchronization shift.

On the other hand, in a general magneto-optical disk drive,
The track signal required for determining the moving direction is, for example, 2
Above 0 kHz, it is extremely disturbed and cannot be used. Therefore,
The processor monitors the moving speed, and when the moving speed becomes sufficiently low that the moving direction may be reversed, the moving direction is determined from the state of the track signal, and the counting direction of the counter is switched or the moving direction is taken into account. It was necessary to switch to the multiple counting method, and the load on the processor was heavy.

[0010] Therefore, an object of the present invention is to solve the above problems,
It is an object of the present invention to provide a position detecting device capable of quickly and accurately detecting the position of a controlled object without complicating the configuration of the device.

[0011]

In order to achieve the above object, the present invention binarizes a one-phase or two-phase sensor output signal detected in accordance with the movement of an object to be controlled. A position detection device for detecting a moving amount and / or a moving speed of the controlled object based on a quantified signal;
When the pulse width information immediately before the binarized signal is input and the waveform of the binarized signal is corrected so that the next pulse edge falls within a predetermined allowable fluctuation range, the pulse state has already transitioned at the allowable minimum position. When the pulse state occurs, the edge is generated at the shortest allowable position. When the pulse edge occurs within the allowable fluctuation range, the edge is left as it is. When the pulse state does not transition at the longest allowable position, the edge is generated at the longest allowable position. It is provided with correction means.

Here, the correction means arranges the pulse width and the permissible variation thereof in the order of the pulse width on a memory designated by the same address, and compares the pulse width and the permissible variation to determine the permissible variation corresponding thereto. It is preferable to adopt a configuration.
Specifically, the allowable variation is set according to the maximum acceleration that the controlled object can take, which is limited by the thrust of the actuator or the command of the controller. Further, when detecting the track position of the optical disk, when the head is moving at a low speed, the position is detected from both the track error signal and the track signal having a phase different from the track error signal by 90 degrees, and the high speed at which the waveform of the track signal is disturbed. When moving, the direction detected at low speed is fixed, and the position is detected using only the track error signal.

[0013]

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

FIG. 1 shows a configuration example of a track position detector of a head in a magneto-optical disk drive device to which the present invention is applied.

In FIG. 1, A is a track error signal detected from a head sensor (not shown), B is a track signal having a phase difference of 90 degrees from the track error signal,
1A and 1B are binarizers, and 2 is a position detector. In the position detector 2, reference numeral 3 denotes a waveform correction circuit (to be described in detail later) (see FIG. 5), 4A and 4B denote D-type flip-flops, 5 denotes a logic circuit, 6 denotes an up / down counter / timer, and 7 denotes a processor.

FIG. 2 shows the binarizers 1A and 1B shown in FIG.
, A track error signal, track signals B and 2
FIG. 5 is a diagram showing a relationship between output values DA and DB.

As shown in FIG. 2, a sinusoidal track error signal A and a track signal B are observed from a sensor (not shown) as the head (not shown) moves.
The position and speed of the head are detected by the position detector 2 based on the signals DA and DB obtained by binarizing the signals A and B by the binarizers 1A and 1B, and the values are read out by the processor 7.
That is, the binary signal Q corrected by the waveform correction circuit 3
A and QB (described in detail later) are D-type flip-flops 4.
A and 4B are input to the logic circuit 5 together with the signals ZA and ZB, and the count signal and its direction signal are output on output lines 8 and 9 and the up / down counter / timer 6
Are encoded as position and velocity. The speed is obtained as the reciprocal thereof by measuring the width of the pulse, that is, the time between each edge, with the timer 6.

FIG. 2 shows waveforms when ideal two-phase signals A and B without disturbance are input. Therefore,
The state transition of the binarized pulse is represented by QA, QB, ZA, ZB.
, The double and quadruple counts can be performed. However, depending on the type of disk drive,
Of the two-phase signals A and B, the track signal B is extremely disturbed in the high frequency range, so that it can be used only in the low frequency range. In this case, a quadruple count (4 counts per track) is also performed using the track signal B only at a low speed, and a double count (only a reliable track error signal A) is used at a high speed seek. (2 counts per track). However, at the time of this double counting, the count is increased or decreased twice by one count so that the gain becomes equal to that at the time of the quadrupled counting. Further, since the waveform of the track error signal A may be disturbed as shown in FIG. 3, the waveform correction circuit 3 performs a waveform correction described below in detail in order to prevent a count error.

Due to factors such as the thrust of the actuator,
The fluctuation amount of the head position is restricted by the acceleration. Therefore, the amount of fluctuation between the pulse width immediately before the track error signal A and the next pulse width has a relationship as shown in FIG.

As can be seen from FIG. 6, the difference between the upper limit (increase during deceleration) and the lower limit (decrease during acceleration) of the allowable variation increases as the frequency becomes lower (low speed), and the upper limit becomes infinite. The point is the lowest frequency that can be corrected theoretically. Actually, in order to suppress unnecessary vibration and overshoot, the acceleration at the time of deceleration is suppressed lower as the speed becomes lower. Therefore, each width of the upper limit and the lower limit can be represented by one value up to a considerably low frequency.

A table as shown in FIG. 7 is provided for the pulse width and the next allowable variation so as to include the upper and lower limits of the allowable variation. According to this table, the next pulse width is limited within the allowable variation range based on the immediately preceding corrected pulse width.

That is, if the next observed pulse width is within the allowable range, it is left as it is, and if it is shorter (ie, if the pulse state has already transitioned at the allowable minimum position), it is set as the allowable minimum value. If the pulse is longer or no pulse edge is observed (that is, if the state of the pulse has not transitioned at the maximum allowable position), the pulse is corrected and output as the maximum allowable value.

The pulse width to be corrected is the interval between rising and falling edges when moving in the same direction as shown in FIG. 4 (1) if the high and low duties of the pulse are substantially equal. If there is a large difference, the interval between the high state and the interval between the low states are individually corrected as shown in FIG. The two-phase signals A and B
For a system in which is obtained with the same reliability, the same correction is performed for each rising and falling edge interval of the two-phase signal.

FIG. 5 shows an example of a digital waveform correction circuit for realizing such a waveform correction process. Here, in the memory table 12, as shown in FIG. 7, the immediately preceding pulse width C [i-1] and the allowable variation value ΔC [i] of the next pulse width are sequentially arranged on the same address. The control unit 11 causes the latch circuit 14 to latch the immediately preceding correction pulse width C [i−1], and stores the corresponding allowable variation amount ΔC [i] in the address TA.
Is scanned and the magnitude is obtained using the magnitude comparator 16. Then, based on the obtained allowable fluctuation amount ΔC [i] and the immediately preceding correction pulse width C [i−1], the allowable minimum value C [i−1] −ΔC [i] and the allowable maximum value C [i of the next pulse are obtained. −
1] + ΔC [i] is obtained by the adder / subtractor 15, and their values and the value C of the counter 13 are compared with the magnitude comparator 16.
, A corrected output is obtained. The value C of the counter 13 when the state of the correction output is switched is latched again by the latch circuit 14 and the counter 13 is cleared.

More specifically, the multiplexer 0 (19) receives the correction pulse width C [i-1] immediately before being latched by the latch circuit 14 and the pulse width output TCQ of the memory table 12, and inputs either one of them. Execute the function to output one or the other.

The adder / subtracter 15 has a multiplexer 0 (1
The output of 9) and the allowable pulse width output ΔC [i] of the memory table (12) are input, and the result of addition and subtraction is output. The addition and subtraction functions are switched by the input signal ADD_SUB.

The multiplexer 1 (17) receives the immediately preceding correction pulse width C [i-1] and the output of the adder / subtracter 15, and
Execute the function of outputting either one.

The multiplexer 2 (18) is connected to the pulse width output TCQ of the memory table 12 and the output C of the counter 13.
And executes the function of outputting one of them.

[0029] Magnitude comparator (16)
Are the multiplexer 2 (18) and the multiplexer 1
The output of (17) is input to the A terminal and the B terminal, respectively, and the function of outputting the comparison results LT and EQ of A <B and A = B is executed.

The control unit 11 receives the signal DA to be corrected and the outputs LT and EQ of the magnitude comparator 16, and outputs a correction signal SA and a reset signal RE of the counter 13.
SET, the latch signal LATCH of the latch circuit 14, the switching signals MUX0, MUX1, MUX2 of the multiplexers 0, 1, 2 (19, 17, 18), the switching signal ADD_SUB of the addition and subtraction function of the adder / subtractor 15, and the address of the memory table 12. The signal TA is output.

With the above, the qualitative operation description of FIG. 5 is completed.

The lowest frequency at which the input signal can be corrected is defined by the lowest pulse width of the memory table 12 (see FIG. 7), and whether or not the input signal has a higher frequency than that, ie, whether or not it has undergone waveform correction. Is output to the logic circuit 5 and the up / down counter / timer 6 via the signal line 10.
Conveyed to. While the waveform is not being corrected, the logic circuit 5 and the up / down counter / timer 6 perform the quadruple counting together with the detection of the moving direction using both the signals DA and DB. Performs counting using only a fixed signal DA while fixing the detected moving direction (the signal of the signal line 9).

The above method can be used not only for the magneto-optical disk but also for the track position detection of other optical disks and magnetic disks, and also for the position detection of general control equipment.

[0034]

As described above, according to the present invention, the position of a controlled object can be quickly and accurately detected without complicating the structure of the apparatus.

More specifically, the following special effects can be obtained.

(1) Even if the pulse signal of the sensor disappears continuously for one to several pulses, restoration correction is appropriately performed. Also, no matter how the pulse signal of the sensor is disturbed outside the allowable fluctuation range, the correction is made without being affected by the disturbance. Therefore,
Position and speed detection errors are eliminated, and controllability is not degraded.

Even if there is a pulse fluctuation due to an operation temporarily exceeding the allowable range, it is corrected in the following direction.
Low possibility of synchronization loss.

(2) It can be realized by a simple digital circuit not including an analog circuit. The pulse synchronization characteristics can be set easily and in detail by rewriting the contents of the memory.

(3) Since the allowable fluctuation amount of the pulse is given in accordance with the maximum possible acceleration of the object limited by the thrust of the actuator or the operation command of the controller, the applicable frequency range is extremely wide (for example, the conventional analog type). (The applied input frequency range is at most about 250 kHz to 1 MHz when the PLL circuit is applied, but is 20 kHz to 5 MHz when the present invention is applied.)

(4) When the present invention is applied to a magneto-optical disk drive, at low speeds, a quadruple count is performed using a track signal in consideration of the moving direction, so that even if an overshoot occurs, it is possible to avoid runaway. Track. At high speed for correcting the waveform of the track error signal, the waveform of the track signal is extremely disturbed. However, since the switching is automatically switched to the double counting using only the track error signal, there is no influence. Also,
The processor does not need to manage the switching of the counting method.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the entirety of a position detecting device to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a track error signal and a track signal waveform of the magneto-optical disk drive device.

FIG. 3 is a diagram showing a state where a track error signal is disturbed in the magneto-optical disk drive device.

FIG. 4 is a diagram illustrating signals before and after correction in a waveform correction circuit.

FIG. 5 is a detailed block diagram of a waveform correction circuit.

FIG. 6 is a diagram showing the relationship between the immediately preceding pulse width and the allowable variation width of the next pulse.

FIG. 7 is a diagram showing the contents of a memory table in a waveform correction circuit that defines the relationship between the immediately preceding pulse width and the allowable variation width of the next pulse.

[Explanation of symbols]

 A Track error signal B Track signal 1A, 1B Binarizer 3 Waveform correction circuit 4A, 4B D-type flip-flop 5 Logic circuit 6 Up / down counter / timer 7 Processor

Claims (4)

[Claims] 1. A one-phase or two-phase sensor output signal detected in accordance with a movement of a controlled object is binarized, and a movement amount and / or a movement amount of the controlled object is determined based on the binarized signal. What is claimed is: 1. A position detecting device for detecting a moving speed, comprising: inputting pulse width information immediately before said binarized signal; and generating a waveform of said binarized signal such that a next generated pulse edge falls within a predetermined allowable variation range. When correcting the pulse state, when the pulse state has already transitioned at the allowable minimum position, an edge is generated at the allowable minimum position, and when a pulse edge occurs within the allowable fluctuation range, the pulse is left as it is, and the pulse state is changed at the allowable maximum position. A position detecting device comprising a correcting means for generating an edge at the longest allowable position when no transition is made. 2. The apparatus according to claim 1, wherein the correction unit arranges the pulse width and the allowable variation amount in the order of the pulse width on a memory designated by the same address, compares the pulse width with the smaller pulse width, and compares the pulse width and the allowable variation. A position detecting device for calculating a variation amount. 3. The method according to claim 2, wherein:
A position detecting device, wherein the position is set in accordance with a maximum acceleration that can be taken by the controlled object, which is limited by a thrust of an actuator or a command of a controller. 4. The method according to claim 1, wherein when detecting the track position of the optical disk, when the head moves at a low speed,
The position is detected from both the track error signal and the track signal having a phase different from that of the track error signal by 90 degrees, and at the time of high-speed movement in which the waveform of the track signal is disturbed, the direction detected at low speed is fixed. A position detecting device for detecting a position using only the position.