JPH0562387A - Speed controller - Google Patents

Abstract

PURPOSE:To realize the stable and quick seek operation in accordance with the characteristic specific to a device without being affected by dispersion in the characteristic of a linear motor, the dispersion of the control circuit characteristic, and the characteristic dispersion due to the temperature characteristic at the time of seek operation. CONSTITUTION:The driving current signal from an F/V conversion circuit 5 or a driving circuit 11 is converted by an A/D converter 9 and is taken into a microprocessor 6, and a maximum allowable acceleration of the linear motor is estimated by this signal, and the set acceleration of a target speed signal is switched to the gain set value of a variable amplifier 8 in accordance with this maximum allowable acceleration to set the acceleration for decelerating operation most suitable for the maximum allowable acceleration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target velocity generator for controlling the velocity of a head moving mechanism to move a beam spot when positioning a target track.

[0002]

2. Description of the Related Art Conventionally, in an optical disk device, when a beam spot is positioned on a target track during recording and reproduction, the distance between the current track and the target track is calculated, and then rough positioning is performed by a head moving mechanism, and then the track is tracked. The beam spot was moved onto the target track by performing the precision positioning operation by the jump operation.

Here, in the rough positioning operation by the head moving mechanism, the moving speed is frequency-voltage converted from the speed detector which is added to the head moving mechanism or the frequency when the beam spot crosses the track of the track error signal while the beam spot is moving. (Hereinafter referred to as F / V conversion) to obtain a speed signal, the head moving mechanism is changed according to the distance to the target track, and the moving speed is controlled by the target speed signal which becomes 0 on the target track. I was positioning near the truck.

[0004] The target speed V _F is the acceleration of this time A, the distance between the current track and the target track and X, V _F
= √ (2AX), which is an expression that gives a target speed for deceleration at a constant acceleration during deceleration.

After the rough seek, the track is pulled in at the target speed 0, the track address is read, the error from the target track is calculated, and the beam spot is moved to the target track by the track jump.

[0006]

In this conventional reference velocity signal generator, the head moving mechanism is accelerated and decelerated in accordance with the target velocity during the rough seek operation, and the target velocity is followed up to the vicinity of the target track. The head is moving.

Since it is desirable to increase the acceleration generated during acceleration and deceleration in order to shorten the seek time, the linear motor is started at the maximum acceleration during acceleration, and is set to a large value within the range that does not interfere with speed following during deceleration. It is desirable to do.

In reality, variations due to variations in the detection sensitivity of the deceleration signal, an increase in the coil resistance of the linear motor due to a rise in the device temperature, variations in the maximum generated acceleration of the linear motor due to variations in the power supply voltage, etc. are expected. It is necessary to set the acceleration during deceleration, which must be set to a value much smaller than the maximum acceleration generated by the linear motor, which has been a factor limiting the seek time reduction.

An object of the present invention is to provide a speed control device that solves the above problems.

[0010]

In order to achieve the above object, in the speed controller according to the present invention, the acceleration generated by the linear motor is detected during the rough seek operation for moving the optical head moving mechanism to the vicinity of the target track. The generated acceleration detecting means and the target speed switching means for switching the deceleration of the target speed signal at the time of deceleration according to the output of the generated acceleration detecting means.

[0011]

According to the present invention, in the rough seek operation of moving the optical head moving mechanism to the vicinity of the target track, the generated acceleration is detected by detecting the amount of speed change per unit time or the driving current of the linear motor, and the generated acceleration is detected. The set acceleration of the target speed is switched according to the output of the detection signal.

[0012]

The present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing an embodiment of the present invention.

In FIG. 1, the track error signal is waveform-shaped by the waveform shaping circuit 1 to form a track crossing pulse, which is input to the track counter 2 and the F / V conversion circuit 5.

The counter 2 subtracts and counts the track crossing pulses at the time of rough seek, and inputs the value to the comparison circuit 3.

The F / V conversion circuit 5 F / V converts the track crossing pulse to generate a speed signal, and a switch (SW).
12 and the differential amplifier 10. The speed signal input to the SW 12 is analog-digital converted by the A / D converter 9 and read by the microprocessor 6.

During a rough seek, the microprocessor 6 registers the error value between the target track and the current track in the track counter 2, the first target speed value in the D / A converter, and the remaining track value for setting the next target value. Start the coarse seek operation.

In the register 4, the value of the number of remaining tracks for setting the next target speed is always set, and the value of the track counter 2 is compared with the value of the comparison circuit 3. When the values match, the output becomes "1". ..

When the output of the comparison circuit 3 becomes "1", the microprocessor 6 newly registers the next comparison value in the register 4
Then, the next target speed value is written in the D / A converter 7.

The target speed signal digital-analog converted by the D / A converter 7 is input to the differential amplifier 10 via the variable amplifier 8 and subtracted from the speed signal.

The differential amplifier 10 outputs an error signal between the target speed and the actual speed, which is input to the drive circuit 11.

The output of the drive circuit 11 is connected to the linear motor and drives the linear motor. At this time, the drive current value passes through the SW 12, is analog-digital converted by the A / D converter 9, and is taken into the microprocessor 6.

Next, detailed operation will be described with reference to the drawings.

FIG. 2 shows the relationship among deceleration, acceleration, seek time and drive current during rough seek. (A) shows a case where the acceleration is small, (b) shows a case where the acceleration is proper, and (c) shows a case where the acceleration is too large. In (a), the seek operation is stable but the seek time is long, and in (c), the seek time is fast, but the speed accuracy at 0 track count is not guaranteed. Further, there is a large error with the target track when stopped, and there is a drawback that stable seek operation is not guaranteed. Therefore, the operation of the apparatus of the present invention will be described with reference to FIGS.

FIG. 3 shows the acquisition of the speed signal and the driving current signal by the A / D converter 9. First, when the two signals are acquired, a seek operation for a long distance is executed and the current signal of the linear motor is changed. The velocities V ₁ and V ₂ at the saturated timing are fetched and the driving current values i ₁ and i ₂ are fetched.

The microprocessor 6 obtains the generated acceleration A ₀ at this time from (V ₂ −V ₁ ) / Δt and calculates the generated acceleration A _i per unit current as A ₀ / A _i1 (i ₁ = i ₂ )

Here, the initial table value of the target speed is stored in the memory of the microprocessor 6, and since this value is set to the standard value of the maximum acceleration generated by the linear motor, the acceleration during deceleration is set. Acceleration of
If there are variations due to variations in temperature, power supply voltage, circuit characteristics, and linear motor characteristics, it will not always be the optimum value.

Therefore, it is understood that it is necessary to optimize the acceleration during deceleration with respect to the acceleration A ₀ generated by the linear motor. In the present invention, in order to set the optimum acceleration value during deceleration for the generated acceleration A ₀ of the linear motor, the variable amplifier 8 is placed after the D / A converter 7, and the target speed signal is multiplied by the coefficient K and output. It can be configured.

By doing so, the deceleration of the target speed can be dynamically switched only by rewriting the coefficient setting value of the variable amplifier without rewriting or switching the original target speed table.

Here, showing the relationship between the coefficient K and deceleration based on FIG. 4, assuming that the original velocity reference signal V _F is acceleration α ₀ and the distance X to the target, V _F = √ (2α ₀ X ) Is set.

When the coefficient K by which the target speed is multiplied is changed, if the original speed at a certain distance X ₀ is V _0, and the coefficient is K ₀ → K ₁ , α ₀ = (V ₀ ² / 2X ₀ ) α ₁ = (1 / 2X ₀ ) · (V ₀ (K ₁ / K ₀ )) ² ⇒ (K ₁
/ K ₀ ) It turns out that it becomes ² bytes.

Therefore, if the generated acceleration A ₀ is obtained,
It can be seen that the optimum acceleration can be set during deceleration with respect to A ₀ . It is also possible to change the coefficient K by observing the acceleration during deceleration as in the case of acceleration.

Next, the case where the drive current is detected and the coefficient K for the target speed signal is set will be described. This is because the drive current reaches saturation even if it is momentary, for example, when the current flowing through the linear motor coil greatly changes instantaneously, such as when the external force applied to the optical head moving mechanism fluctuates due to disturbance. In some cases, the speed tracking accuracy is reduced and the stability of the seek is impaired. At this time, however, by lowering the coefficient by which the target achievement speed is multiplied, it is possible to increase the margin for the acceleration generated by the linear motor.

Further, similarly to the case where the acceleration is estimated from the change amount of the speed signal, it is possible to estimate the generated acceleration from the drive current value and optimize the target speed. Assuming that the generated acceleration of the linear motor is A ₀ , the force constant is K _F , the drive current is I, and the weight of the moving part is M, A ₀ = (K _F / M) I, and the generated acceleration is driven by A _0. This is because it is proportional to the current I.

This is because when the drive current fluctuates due to fluctuations in the power supply voltage or an increase in coil resistance due to heat generation, the generated acceleration fluctuates. Therefore, it is possible to detect the fluctuation of the generated acceleration by detecting this driving current. Is.

In the present embodiment, the variable amplifier is used for switching the target speed, but the target speed value may be set in the D / A converter after the microprocessor executes the multiplication of the coefficient, or the target speed may be set. It is also possible to set some tables and switch and use them according to the generated acceleration. Further, the amplitude of the target speed signal may be switched using a variable gain amplifier.

[0037]

As described above, according to the present invention, the generated acceleration can be estimated from the speed signal at the time of the rough seek or the driving current of the linear motor, and the deceleration can be optimized with respect to the maximum generated acceleration at the time of acceleration. It is possible to always set the optimum value against variations in characteristics, variations in force constant of the linear motor, variations in drive current due to variations in power supply voltage, etc., and stable and highly reliable seek operation becomes possible.

Further, since it is not necessary to set the acceleration to a low value in anticipation of a decrease in the margin for the generated acceleration due to the variation factor, there is an effect that the seek operation can be speeded up.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an operation signal waveform diagram at the time of seek.

FIG. 3 is an explanatory diagram of acceleration detection.

FIG. 4 is an explanatory diagram of a target speed setting operation.

[Explanation of symbols]

 1 waveform shaping circuit 2 track counter 3 comparison circuit 4 register 5 F / V conversion circuit 6 microprocessor 7 D / A converter 8 variable amplifier 9 A / D converter 10 differential amplifier 11 drive circuit

Claims (1)

[Claims] 1. A generated acceleration detecting means for detecting the generated acceleration of a linear motor during a rough seek operation for moving an optical head moving mechanism near a target track, and a target for deceleration according to an output of the generated acceleration detecting means. And a target speed switching means for switching the deceleration of the speed signal.