JPH02152019A - Tracking controller for optical disk - Google Patents

Abstract

PURPOSE:To increase the track jump speed by commanding kick termination and brake start ahead of zero-crossing and changing the distribution to shorten and extend the kick time and the brake time respectively. CONSTITUTION:A time delay detecting circuit 15 receives the kick start command to start detection and detects the time from zero-crossing to the start of operation beyond an error range of a track error signal (c) to calculate the extent of phase lead and detects the time from the actual kick start to zero-crossing near the kick end and the brake start. The extent of phase lead determined in this manner is controlled furthermore and is updated by a phase lead extent controller 16. This signal is an extent c' of phase lead connected to a mode changeover switch 18 when this switch 18 is switched to the update side, and the timing of zero-crossing near the kick end or the brake start is advanced by this extent c' of phase lead, and a new kick time is calculated and stored.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a recording and reproducing device for optical disks and magneto-optical disks (hereinafter referred to as optical disks).
The present invention relates to a tracking control device for obtaining a jumping motion.

[Conventional technology]

One of the important functions in an optical disk recording/reproducing device is a tracking function that performs follow-up control so that a recording or reproducing beam spot accurately traces an information track.

FIG. 2 is a block diagram showing a conventional tracking control device for an optical disk recording and reproducing apparatus, particularly for an optical disk recording and reproducing apparatus. 1 is the track, 2 is the main spot which is a convergent light spot for reproducing the signal from trunk 1, 3 is the main spot
4 are sub-spots that are optical spots placed before and after the main spot 2 for obtaining track control information; 4 is a reproduction signal amplifier for photoelectrically converting and amplifying the optical information into an electric signal after obtaining the optical information; 5 is an error signal generation differential amplifier (
C) is a track error signal that is the output of the error signal generation differential amplifier 5, 6 is a servo signal amplifier that amplifies the track error signal (C), and 7 is a trunk servo control that turns on/off the output of the servo signal amplifier 6. 8 is an adder for adding a kick pulse or brake pulse (hereinafter referred to as kick/brake pulse (a)) to the output of servo switch 7; 9 is the output of adder 8; A current amplifier 10 for amplifying the main spot 2 and sub spot 3 is connected to the current amplifier 9.
a trunking actuator for moving in a direction perpendicular to the track 1, 11 a zero-cross detection circuit connected to the error signal generation differential amplifier 5 and for detecting the zero voltage level of the track error signal (c), 12 a track servo A jump control sequence circuit 13 generates system opening/closing commands and track jump commands; 13 is a kick pulse generation circuit for generating kick pulses in response to commands from the jump control sequence circuit 12; and a kick pulse generation circuit 13 for generating brake pulses. Brake pulse generation circuit for (b
) is from the current amplifier 9 to the tracking actuator 10
(d) is the zero-cross signal from the zero-cross detection and calculation circuit 11, and (a) is the kick/brake pulse from the kick/brake pulse generation circuit 13.

Next, the operation of the above conventional example will be explained using FIG. In the conventional recording and reproducing apparatus described above, in a normal reproducing apparatus, the tracking information obtained from the sub-spot 3 is converted into a track error signal (C) by the error signal generation differential amplifier 5, and this track error signal (C) is used for tracking. was in control.

That is, at this time, the jump control no-ken circuit 12 issues a command to close the servo switch 7, and the servo switch 7 is closed. Therefore, the trunk error signal (
C) is applied to the trunking actuator 10 through a servo signal amplifier 6, a servo switch 7, an adder 8, and a current amplifier 9. As a result, the tracking actuator 10 controls the main spot 2 to be located at the center of the track 1, and the reproduction signal amplifier 4 obtains an appropriate reproduction signal.

By the way, when performing a track jump operation to change the playback track to an adjacent track, first open the tracking servo switch 7 to release the servo, and then generate a kick pulse (a) from the kick/brake pulse generation circuit 13. ), and the zero-crossing signal (C) of the track error signal (C) at the midpoint between the spot and the adjacent trunk.
Adjust the performance of the tracking actuator 10 so that the kick pulse ends when d) is output, and then generates the brake pulse. Also, adjust the performance of the tracking actuator 10 so that the brake pulse ends at the next zero cross point, and then Switch 7 was closed to re-form the servo loop and allow the servo to work.

However, depending on the rising and falling slew rate of the current amplifier 9 and the mechanical time constant of the tracking actuator 10, the kick/brake pulse (a) and the tracking error signal (C ) There is a time delay between

The time delay will be explained in detail. FIG. 3(A) is a waveform diagram showing the state of tracking, in which (a)
is the waveform of the kick/brake pulse (a) which is the output of the kick/brake pulse generation circuit 13, (b) is the waveform of the tracking signal (b) which is the output of the current amplifier 9, and (C
) shows the waveform of the track error signal (C), (d) shows the waveform of the zero cross signal (d), and (e) shows the spot speed, respectively.

There is a time delay between the rise of the waveform of the ten clock pulse (a), that is, the start of a kick, and the zero crossing shown in the waveform (C) of the track error signal, that is, until the kick is actually applied. Let this time delay be T1. And even before the kick ends and the brakes are applied,
There will still be a time delay. The time delay at this time is assumed to be T2. During this time delay T2, due to inertia at the speed at the end of the kick, the vehicle passes beyond the zero-crossing position at which it is desired to start braking. Here, the time delay T2 is considered to be in almost the same situation as the time delay T at the start of the kick, so these are set to the same value T1. In other words, the brake is actually applied when there is a delay of time TI, or in other words, when the zero-crossing signal (d) is detected and the kick pulse (a) is finished, but the brake is actually applied by the time delay T1 when the speed at the end of the kick is applied. This starts from point A, when the point of zero crossing has been exceeded. Therefore, the brake or deceleration time T is the same as the kick or acceleration time TA.
If we take , and if we start decelerating with the same voltage as the acceleration voltage, at time B when braking ends, the spot velocity with respect to the groove will be zero, but the spot position with respect to the groove will be
The original control point C, which is the zero cross, has been exceeded by approximately the same amount as the amount of progress made due to inertia during the time delay T1 between the end of acceleration and the actual start of deceleration.

That is, if the time from the start of braking until reaching the original control point C is T, then Tc = (Ts Tl) < T++ = Tll. In order to use the servo to return to the zero-crossing point after passing the point C and reaching the point B, it will take a considerable amount of time T8 for the servo to settle. Moreover, even if the brake is finished at the time point C, since the speed is still increasing, it will still take a long time Tw to stabilize the vehicle.

Therefore, the conventional servo settling time T1. l
In order to reduce this, as shown in Figure 3 CB), braking, or deceleration, is performed in a shorter time and at a higher speed than kicking, or acceleration, so that the end of braking is near the original control point C. B°, and the speed at that time is 0
The brake time and speed were set to be close to . The settling time T8 at this time was smaller than Tw shown in FIG. 3 (A). However, the higher the speed before settling, that is, the greater the degree of deceleration, the more time is required for settling, the more energy is wasted, and the track jump cannot be said to be stable or high-speed.

Also, in order to make deceleration faster than acceleration, it is possible to increase the current capacity during deceleration by increasing the current capacity of the circuit related to the actuator or increasing the number of turns of the electromagnet winding. , it is necessary to increase the performance of the electromagnet with some margin in advance, and therefore, conventionally, the performance of the electromagnet has not been used effectively.

Another absorption method for the time delay T1 is that deceleration is better than acceleration when compensating for errors caused by fluctuations in tracking actuator sensitivity, circuit errors, temperature characteristics, etc., which exist as a practical problem. There is a way to efficiently adjust it to make it stronger, but the performance of each element is rate-limiting, and each has its own performance limit, so it is impossible to find the optimal combination for -C, and in the end it is impossible to find a combination that is optimal for -C. Speeding up could not be achieved.

[Problem to be solved by the invention]

The present invention has been made in view of these conventional problems, and its purpose is to perform track jumps at high speed.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inventor realized that it is sufficient to change the distribution of the kick time and the brake time so that the kick time is shortened and the brake time is lengthened.

The present invention includes a means for detecting a time delay TI between the kick pulse command (a) and the actual movement of the tracking actuator 10, and a phase advance amount adjustment capable of further adjusting approximately half the value of the output of the time delay detection means 15. means 16, and zero-cross detection and calculation means 11" which detects the zero-cross signal (d) and calculates the phase advance by the amount of the phase lead ffi (C') from the phase at that time. In other words, the brake start command is issued earlier than the zero cross, and the vehicle progresses by inertia until the brake is actually applied at a distance traveled during the actual kick, that is, acceleration time, and at a speed close to the speed at the end of the acceleration. Add up the distance and the distance traveled during the actual braking time, and end the kicking time TA' earlier than the zero cross and start braking at the same time so that the total distance approximately matches the trunk interval. , the kicking time TA' and the braking time TI' were distributed to enable high-speed trunk jumps.

[For production]

In the present invention, the time delay numerator from when a tracking kick command is received until the kick operation actually starts is detected in advance, and after calculating the time T1'' which is approximately half of the time delay T1, the actual kick is started. Phase advance i (C'
), the kick end point is advanced in phase by the time delay T1'' from the point when the trunk error signal (C) reaches zero crossing, that is, the point when the spot position reaches the center between the tracks. To' By distributing T,° earlier than T,°, it is possible to terminate the braking near the zero crossing of the original control point and thus reduce the time it takes for the servo to settle, TI,゛, considerably to, for example, almost O. , high-speed trunk jump operation becomes possible.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. Second
The same symbols as in the figure represent the same effects.

1F is a zero cross detection and calculation circuit; 15 is a circuit that detects a time delay T1 until the kicking operation actually starts while receiving a kick command; 16 is a time delay detection circuit 15
a phase advance amount adjuster that receives the signal, calculates a half time of the time delay T1, and finely adjusts it to determine a phase advance amount TI that advances the timing of the kick end brake start command from the zero cross timing; Reference numeral 17 indicates a phase advance initial value setter that can be set to, for example, about 1/10 of the entire kick time, and 18 indicates a signal mode of the phase advance initial value setter 17, a signal mode of the phase advance amount adjuster 16, and the like. You can select and switch between three modes, including a signal mode that retains the previous phase lead amount without receiving either information, and select one of them to use as the phase lead amount (C゛) signal. Mode changeover switch, (C'') is the phase lead amount signal, 11° is the zero cross that subtracts the phase lead amount signal (C゛) from the timing of the zero cross signal (d) when the zero cross point is detected from the track error signal (C). This is a detection and calculation circuit. Here, the theoretical optimum value is when the phase advance amount TI' is T1"= (1/2) ・T1, and at this time, the time TA" from the start to the end of the kick pulse (a) is TA = TA - T #TA - (1/2) ·T.

Using FIG. 1, the operation of track jump position control according to the present invention will be explained separately for the case of track jump phase advance (updating mode (2)) and normal mode (2).

■Updating mode of phase advance amount: Use this mode at the beginning of using the optical information recording device.

The jump control sequence circuit 12 opens the servo switch 7 and sends a kick command to the kick/brake pulse generation circuit 13, where it is converted into a desired kick pulse voltage, passes through an adder 8, and is amplified by a current amplifier 9. After that, the tracking actuator IO is accelerated.

Initially, the mode selector switch 18 is on the initial value side, and the phase advance initial value setter 17 stores the phase advance amount as an initial value, for example, approximately one-tenth of the kick time TA; The phase advance it T+ determined by
The zero cross detection and calculation circuit 11 deducts the zero cross point from the timing when the zero cross point near the end of the kick sent from the track error signal (C) is detected, and the result is sent to the jump control sequence circuit 12, and at that timing, the actual Finishes the kick and issues a command to start braking.

On the other hand, the time delay detection circuit 15 starts detection upon receiving a command to start kicking, and when kicking actually starts, that is, when the trunk error signal (C) starts moving beyond the error range from zero cross. The amount of phase advance T, is calculated by detecting the time T, and the time TA from the actual kick start to the zero cross near the end of the kick and the start of the brake.

The thus determined phase lead amount T1° is transmitted to the phase lead amount adjuster 16. In this regulator, the phase advance! it T
+' can also be manually adjusted, for example by ±Tl°.

The phase lead amount adjuster I6 updates the tU lead amount. When the mode changeover switch 18 is set to the update side, the signal is transmitted to the phase advance ffi connected here.
(C'), zero cross detection and calculation circuit II°
The timing of the zero cross near the end of kick or the start of braking is advanced by this phase advance I (C''), and a new kick time TA' is calculated and recorded as TA = TA (1/2) ・T. Ru.

■Normal track jump mode: In optical information recording devices, this mode is used except at the beginning when the medium conditions change significantly.

In this mode, since the mode changeover switch I8 is in the OFF state, the time delay detection circuit 15 and the phase lead amount adjuster 16 do not operate, and the phase lead I (C') phase lead 119 is not updated, so the zero crossing Phase advance amount T previously determined and stored in the detection and calculation circuit 11°
Kick time TA° obtained by subtracting ,゛ from kick time TA
is now used.

As shown in FIG. 4, the jump control sequence circuit 12
The kick command (Fig. 4a) is the track error signal (C
) (Fig. 4C) at a point earlier than the first zero cross point after the kick command, the command changes to a brake command. The time is the point D° which is obtained by subtracting the phase advance star T+' from the zero crossing point.
(Fig. 4 c'). The time from the start of the kick to this point is the kick time TA°.

Braking is started immediately after the kick ends, and the speed is decelerated during the braking time T,'' until the end of the brake. Then, the servo switch notch 7 is closed and the follow-up servo state is entered (Fig. 4 C1c'). , the settling time T-'' required for the servo at this time is the same as the previous Tw even if the brake ends before or beyond the original control point.
or Tw". Also, the kick time at this time is 1-
The sum of A+ and brake time 71' is the time T required for the servo. It is desirable to take the optimal value that minimizes .

As a result, at the end of braking B'', the trunk error signal (C), that is, the spot position (C in Fig. 4) and the spot speed (e in Fig. 4) become close to zero, and the brake is stopped near the original control point C. I can see that I am able to finish it.

In this case, the track jump operation has good stabilization after the braking is completed and can be completed efficiently without requiring unnecessary settling time.

Note that TIl'' reaches the zero cross when the brake is finished at T m = TA, and its speed and position become O, but if both the gain and band of the tracking servo system can be kept high enough, T,'' It will be faster if you start settling before the zero cross after a little bit of TA.

Here, the brake pulse voltage is the inversion of the kick pulse voltage.

〔Effect of the invention〕

As described above, according to the present invention, compared to the conventional method of decelerating when the zero-crossing point of the track error signal is detected,
Since it is possible to start optimal deceleration at an earlier timing, the braking time can be longer than before, and the sum of the kick time and the braking time becomes smaller, thus reducing wasted time. This has the effect of saving a lot of time and energy, that is, speeding up the track jumping operation.

Further, in order to correct the amount of phase lead, that is, the amount of time delay, the above effect can be obtained by simply adding a simple circuit to the conventional circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment according to the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. FIG. 3 CB) shows the waveforms of each signal for explaining the operation at the time of track jumping in the improved conventional example, and FIG. 4 shows the waveforms of each signal for explaining the operation at the time of track jumping in the embodiment. [Description of symbols of main components] 11...Zero cross detection and calculation circuit 12...Jump control sequence circuit 13...Kick/brake pulse generation circuit 15...Time delay detection circuit 16...Phase lead FJk adjuster 17...Phase lead amount initial value setter 18...Mode selection switch (a)...Kick/brake pulse waveform (b)
...Tracking (No. 3 waveform (C) ...Track error signal waveform (Co) - Phase advance waveform (d) ...Zero cross signal waveform (e) ...Spot speed waveform Figure 4 (AE) TA = Tsf)'t TA > Tsf) Fig. 5

Claims (1)

[Scope of Claims] Means for detecting a time delay between the kick pulse command and the actual movement of the tracking actuator, and a phase advance adjustment means capable of further adjusting a value based on the output of the time delay detection means; A zero-cross detection and calculation means is provided which detects a zero-cross signal of the track error signal and calculates by subtracting the amount of phase advance from the phase at that time;
A track position control device for optical information recording that enables high-speed track jumps to occur earlier than the zero cross.