JPS58200472A - Tracking controller of recorded information reproducer - Google Patents

Abstract

PURPOSE:To attain stable jumping control not affecting the position of an actuator, by applying an accelerating pulse to a reading means, receiving an output detecting a specific position, applying a decelerating pulse, closing a control loop after the end of application and performing the jumping control. CONSTITUTION:When a trigger pulse of a jump instruction is inputted to a jump instruction input terminal 21, an output of a D-FF18 goes to ''High'' and a switch 11 is closed. Further, an output of the FF18 is inputted to an addition/ subtraction amplifier 26 and applied to the actuator 14 as the accelerating pulse. When the actuator 14 comes to the center between tracks, since a pulse is generated from a specific position detector 17 between the tracks, a leading pulse is inputted to the clock input of the FF18 and a Q output goes to ''Low''. The output of a multivibrator 32 goes to ''High'' by the trailing of pulse, the output is applied to the input of the amplifier 26 while keeping the loop open, a pulse of the opposite polarity and the accelerating pulse are produced and the actuator 14 is driven in the decelerating direction and braked. The loop is turned on after the end and the jumping scanning is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to information track skip control in a recorded information reproducing apparatus such as a DAD player or a video disc player.

To read information on a digital audio disk (DAD), the intensity of reflected light or transmitted light from the recording surface is modulated depending on the presence or absence of pits recorded on the uneven surface of the disk. This is done by detecting. The signal track of the disk is in the shape of a five-fold spiral, and a reading device for such an information recording disk is provided with a tracking servo device for always accurately tracking the irradiated light on the signal track of the disk. Although there are various methods of detecting a tracking error signal for performing tracking servo, a method called a three-spot method will be described here.

FIG. 1 is a diagram for explaining the principle of tracking error signal detection and the operation of tracking servo. When the switch 11 is open, the reading device does not follow the track, so the signal track will cross over the optical spot for reading due to eccentricity of the disk.

Reading the signal information when a truck passes over the optical spot A) Photoelectrically converting the output signal from A and photoelectric converter 1. B) Photoelectrically converting the output from spots B and C for detecting track errors. In FIG. 1, the diagonally shaded portions of spots A, B, and C indicate portions that weakly reflect light. In FIG. 1, a indicates the track on which the signal is recorded, and b
indicates the area between tracks. In the same figure, the D level of the output signal of the A spot indicates the so-called Dacrepel where the output of the detector is 0 because there is no reflected light, the M level indicates the so-called specular level where the reflected light is maximum, and R indicates the readout level. 3 shows an envelope line in which the bit surface level changes as the track traverses A.

The method of reading signals by following the signal track using five spots (A, B, and C) is called the 3-spot method.
B and C are integrated.

Therefore, the tracking error signal changes depending on the spot positions in FIG. 1B and C. When the A spot is located at the center of the track, the B and C spots are set so that half of them are located at the track hK as shown diagonally, and their optical outputs are the same, so the tracking error signal B-C
+io, and when the spot moves relatively to the right on track a where the signal is recorded, the B spot is a mirror surface, and the C spot is located on the track, so it is positive, and when it moves to the left, it is a negative voltage. If the track interval is generated, the opposite is true, and if the reading spot moves relatively on the track as shown by the arrow due to deviation from the track center, then vc
The waveform becomes as shown in +t%. The tracking error signal, which is the output of the differential amplifier 8, is sent to the switch 11, the phase compensation circuit 12, the amplifier 13, and the dry transistor 1.
5.1<S is applied to the tracking actuator 14, and this movement is captured by detectors B and C to form a servo loop.

FIG. 2 shows only a one-way skipping circuit of the well-known track jumping fa control circuit.The operation of FIG. 2 will be described below.

In FIG. 2, 17 is an inter-track specific position detector, 18 is a D type flip-flop (hereinafter abbreviated as 1-FF), 19 & 1 differentiation circuit, 20 is an adder, and 21 is a jump command input terminal. When the trigger pulse shown in (f) is input to 21, a trigger is applied to the set terminal of D-FF1B, and the output Q of 18 becomes high level. (b)
When the switch 11 is opened, the output of 19 is inputted to the differentiating circuit 19, and the output of 19 (weak) is added to the servo circuit by the adder 20, and a differential pulse is applied to the actuator 14.

This pulse causes the actuator to start jumping motion,
In (b), an S curve is output. The position detector 17 is composed of a comparator, and when the S curve becomes higher than a level slightly higher than the zero level shown in (c), a pulse shown in (g) is outputted from the position detector 17.

The rising edge of the waveform (g) is located slightly beyond the middle of the tracks. Detect this position and D-FF
When a rising pulse is input to the CK terminal of 18, a low level is input to the D input, and the D-1 = "F output becomes low. The switch 11 is closed, and a falling differential pulse is input to the actuator 14. Then, a deceleration operation is performed and jump control is performed.

By the way, the actuator is generally fixed with a spring suspension. If the actuator is located at the physical center, the return force of the spring is small and poses no problem, but as the actuator repeatedly jumps, the actuator moves away from the center position and the spring return force gradually increases. Movement speed becomes slower. Therefore, when the actuator is far from the center position, the time for detecting the center position is delayed by T compared to when the actuator is at the center position (1), as shown in FIG. 5(b). Figure 3 (a) (b)
[As shown, if the time constant of the differential is small, the energy applied to the actuator will not increase even if the time is lengthened, and a phenomenon will eventually occur where the actuator cannot reach the center position between the tracks. In other words, it becomes impossible to jump over one track. To solve this problem, if the time constant of the differential is increased, the energy applied to the actuator increases with time as shown in Figure 13 (C)K, but the amplitude of the deceleration pulse in the opposite direction is This results in a phenomenon in which the energy decreases and the braking is not applied properly. In other words, it goes too far by one track or more. As described above, the further away from the physical center of the actuator, the more unstable the jump control becomes.

In addition, if the amplitude E of the jump pulse cannot be made sufficiently large for the tracking error amplitude F as shown in Fig. 4 due to reasons such as low power supply voltage, the loop is turned on and a deceleration pulse in the opposite direction is applied. Even so, as shown in FIG. 4(h), the error signal (f) shown by the broken line and the deceleration pulse (e) cancel each other out, so that the deceleration pulse does not work effectively and the braking becomes unstable. In FIG. 4, (e) shows a jump pulse at the actuator terminal. (fl indicates an error signal at the actuator terminal when the loop is off.

Since (f) is a signal for the purpose of applying servo to reduce displacement, its polarity is opposite to (e). (g) shows whether the loop is on or off. High level is loop on state.

Therefore, when the loop is turned on after the center is detected and a deceleration pulse is applied, the signal (f) with the opposite polarity to ej is added, and the level (f) is subtracted from the signal (e) (h).
Only the signal of 1 becomes a deceleration pulse, resulting in insufficient control and
The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to stably perform jump control even when the actuator is far from the physical center and when the amplitude of the jump pulse is small. The object of the present invention is to provide a tracking control device that can perform the following tasks.

The tracking control device of the present invention applies a constant voltage pulse so that the energy applied to the actuator increases over time even when the return force of the spring increases, and after detecting a specific position, the constant energy deceleration pulse remains looped off. After the deceleration pulse ends, the loop is turned on to perform stable jump control regardless of the actuator position.

An embodiment of the present invention will be described below with reference to diagram WJ5. Fifth
In the figure, 1 to 16 indicate the same items as in FIG. 1.

17 is a D-FF after detecting a specific position between tracks, 52
is a monostable Martino (ibrator) with a resistance of 25 and a capacitance of 2
4, the pulse width is determined. 26 is an addition/subtraction amplifier, which adds the acceleration pulse of the 1B output and the deceleration pulse of the 32 output so that they have opposite polarities, and the adder 20 adds the pulse width to the control loop. and drives the actuator 14. Reference numeral 31 is a loop opening/closing signal generation circuit, which is composed of an OR circuit.A specific position detection circuit 17 includes an envelope detector 41 for the read information signal, and a comparison circuit 22 and 23. The envelope level of the read information signal of 41 outputs is determined by the 22 comparators as shown in Figure 5 (a).
When the signal is below a certain level, that is, when the signal is detected at a certain level or above, a high-level signal indicating IK is output. By doing this, a pulse rising at the center between the tracks as shown in (g) can be obtained.31
is a loop opening/closing signal generator, and the output is at a high level and the yr reswitch 11 is opened during the D-PF 18 output, that is, the acceleration pulse generation period, and the monostable multivibrator 32 output, that is, the deceleration pulse generation period. The fifth component consisting of the above components
When the trigger pulse for the information track jump command (to) is input to 21 in the figure, the output of D-F'F1B becomes high, and 3
The switch 11 is opened via the switch 1. On the other hand, D-FF1
The output of 111 is input to 26 adding/subtracting amplifiers and applied to the actuator as an acceleration pulse. Since this acceleration pulse is a constant voltage, even if the spring return force increases,
By increasing the time, that is, the pulse width, the energy for driving the actuator can be made larger than in the conventional example. When the actuator comes to the center between the tracks due to the acceleration pulse, the pulse shown in (g) is generated from the 17 specific position detectors. Therefore, a rising pulse is input to the clock input of 18, and the Q output of 18 becomes low.This fall causes the multivibrator output of 32 to become high, and the output of 51 becomes high.
is applied to the input of the adder/subtractor amplifier 26, leaving the loop open via the acceleration pulse, and a pulse of opposite polarity to the acceleration pulse is applied to the input of the accelerating pulse. . ,.

brake is applied. The output of the D-FF 18 is as shown in the output of the monostable multivibrator 52.
As shown in Figure 9, the output of the adding/subtracting amplifier of 6 is the amplitude ratio V*/
V* can be freely set by changing the resistance ratio of 27.28.29.3o.

As explained above, according to the track jumping control circuit shown in FIG. 5, regardless of the position from the physical center of the actuator, and even if the track error signal amplitude and deceleration pulse amplitude are close to each other, stable jumping control can be performed. It is possible to do this.

In addition, by setting the deceleration pulse amplitude (■) larger than the acceleration pulse amplitude (1), the deceleration pulse width can be shortened, and the speed when the actuator is located at the center between the tracks can be decelerated in a short time. It becomes possible. For this reason, it is possible to eliminate the amount of overshoot during track jumping, and since the loop response after jumping becomes smaller, the time for jumping Kl' can be shortened.

This has been explained above. Similarly, according to the present invention, it is not affected by the position of the track actuator (that is, the magnitude of the return force of the spring), and is stable even when the power supply voltage is low and the track error amplitude and the jumping pulse amplitude are the same. It became possible to perform jumping control. In addition, by setting the deceleration pulse amplitude to be thicker than the acceleration pulse amplitude, it is possible to reduce fluctuations in the loop characteristics after jumping and to shorten the time required for jumping, which is convenient.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the tracking control loop, Figure 2 is a conventional block diagram, Figures 3 and @4 are explanatory waveform diagrams of conventional interlaced signals, and Figure @5 is a circuit showing an embodiment of the present invention. It is a diagram. A...Signal information reading spot B, C...Tracking error detection spot 6.7
...Photoelectric converter 8...Differential amplifier 11...Switch 12...Phase compensation circuit 1S...Amplifier 14...Tracking actuator 15.1 (S...
...Driver transistor 17...Inter-track specific position detector 18...D tap 7 Rigging flop 19...Differentiating circuit 2n...Adder 21...Jump command input terminal O 1 Figure 7j o-1, −−−11−−−−−−−−−−Second mortar. g) - "-] - 73 countries? 4th Koku 5th Koku 1" Jl 1- 2' Seven Sho-1

Claims (1)

[Scope of Claims] t. In a reproducing device for a recording medium in which information is recorded in a spiral shape, a tracking signal detection means for a reading means to track a recording track, and a tracking control is performed in accordance with the tracking signal. A control loop, an acceleration pulse generation method for accelerating the reading means in a predetermined direction, a specific position detector for detecting that the reading means has reached a specific position between recording tracks, and the reading means driven by the output of the specific position detector. The control loop is equipped with a deceleration pulse generator that generates a deceleration pulse, and a disconnection device that opens the control loop while at least the acceleration pulse and the deceleration pulse are being output. Open the loop to the cutting device, apply an acceleration pulse to the reading means, receive the output from the specific position detector, apply a deceleration pulse, and after the application of the deceleration pulse is finished, close the control loop described in E to perform information track jumping control. A tracking control device for a recorded information reproducing device, characterized in that: 2. A tracking control device for a recorded information reproducing apparatus according to claim 1, wherein the pulse width of the deceleration pulse generator is set to a fixed value regardless of the pulse width of the acceleration pulse. (5) Claim 1, wherein the pulse amplitude of the acceleration pulse generator is larger than the pulse amplitude of the acceleration pulse, or
A tracking control device for a recorded information reproducing device according to item ig2.