KR900006961B1 - Device for controlling rotation speed and phase of disk - Google Patents

Abstract

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Description

Device for controlling rotation speed and phase of disk

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

FIG. 2 is a waveform diagram showing signal waveforms of respective parts in FIG.

3 is a waveform diagram showing an operation principle of phase difference detection used in the present invention.

4 is a waveform diagram showing an operation principle of speed difference detection used in the present invention.

* Explanation of symbols for main parts of the drawings

1 terminal 2 monostable multivibrator

3: phase difference detector 4: terminal

5: Sample hold circuit 6: Phase compensation circuit

7: resistor 8: capacitor

9: resistance 10: switch

11: constant current source l2: capacitor

13: diode 14: buffer

15: Output terminal.

The present invention relates to a control apparatus for controlling a drive motor of a disk to match the rotational speed and the phase of rotation of the video disk to a reference value in order to eliminate time-side variation of the playback signal in the video disk player. In particular, the present invention relates to the most suitable control device by applying to a constant linear velocity (VLV) type disk.

A speed control method of a disc for reproducing a signal from a fixed speed disc (hereinafter referred to as CLV disc) without time axis variation is disclosed in Japanese Patent Laid-Open No. 57-30144. However, this method does not consider the accuracy of the position detection potentiometer used when detecting the position of the optical spot along the radial direction of the disc by the necessity of control and the error of the linear velocity during recording. This error must be taken up by the phase change control side of the disc.

In addition, when playing an angular speed disc (hereinafter referred to as a CAV disc) on the same device (disc player), it is necessary to switch the speed control target to a fixed target value different from that of a CLV disc, which is not so good in terms of handling. There was

The object of the present invention is that the disc to be used can be used in the same use method without requiring a special operation such as switching the target value irrespective of the CAV disc or the CLV disc. It is to provide a rotational speed phase control apparatus for a disc capable of eliminating time-base fluctuations in a playback signal without being affected by the speed error.

The drawback of the conventional control method is due to the selection of the reference value, which is the speed target value, as a constant voltage. In order to overcome this, a reference signal (a source of this signal is referred to as a reference frequency power source) generated at a predetermined period serving as a reference value of the rotational speed of the disk is generated, and the horizontal synchronization included in the reproduction source video signal in the disk. The signal may be compared as a signal indicating the rotational speed of the disk, the speed and phase difference between the two are detected, and the speed and phase control may be performed so that this becomes zero.

As the most suitable speed and phase difference detector used in this, there is a phase difference detector of an edge control digital memory type. However, this type of phase difference detector has the disadvantage of being able to have a controllability of the rotational speed and to be easily malfunctioned by noise. In other words, when this is applied to an optical video disc player, noise may invade a synchronous signal reproduced by reproducing the disc by dropouts or the like on the disc surface, and the apparent horizontal synchronization frequency may change. As a result, an edge control digital memory phase difference detector alone is insufficient as a detector for speed and phase control.

Thus, a phase difference detector generates a trapezoidal wave using a reference signal generated from a reference frequency power source for a trigger, and samples the trapezoidal wave using a horizontal synchronous signal included in a reproduction signal from a disc, and at the sample value. The phase difference detector is used, and the phase difference detector of the edge control digital memory type described above is used as the speed difference detector, and the phase of the inclined surface opposite to the use slope (negative environment slope) of the trapezoidal wave described above is speeded up. It was made to control by the output of a difference detector.

Hereinafter, the operation principle of the present invention will be described in more detail.

First, the principle of phase difference detection will be described with reference to FIG. In FIG. 3, (a) shows a reference signal output from a reference frequency power supply, (b) shows a trapezoidal wave generated by being triggered by the reference signal, and (c) shows a reproduction signal from a disc. Displays the horizontal sync signal extracted from.

In this case, the reference signal a indicating the reference value of the rotational speed of the disk and the horizontal synchronizing signal c, which indicates the actual rotational speed of the disk, are almost in a locked state. If the sample value obtained by sampling the trapezoidal wave b with the horizontal synchronizing signal c is S1, the phase difference between the reference signal a and the horizontal synchronizing signal c is given by this sampling value S1. If the relative phase with respect to the reference signal (a) of the horizontal synchronization signal (c) fluctuates like the pulse (1) indicated by the dotted line, the sample value at that time is S2. Therefore, the difference between S1 and S2 is obtained by determining the difference between I can see the change

Therefore, the change in the relative phase can be corrected by controlling the drive motor of the disc by using the trapezoidal (b) sample value of the horizontal synchronizing signal (c).

Next, the principle of speed difference detection will be described with reference to FIG.

In this case, the reference signal a and the horizontal synchronization signal c are in an unloCk state. In other words, the first side of the reference signal (a) is phased ahead of the horizontal synchronous signal (c) gradually approaches, and finally the side of the reference signal (a) is later than the horizontal synchronous signal (c). Also happens. At this time, if the reference signal (a) is ahead of the horizontal synchronous signal (c) as the speed difference signal (d), it is positive if it is positive, and if it is late, it takes negative polarity. When a signal expressed by the pulse width is generated, the speed difference between the two signals can be known.

Next, a method of controlling the drive motor of the disc so that the speed difference becomes zero by using the speed difference signal r obtained as described above will be described.

The length of the duration t of the upper side of the trapezoidal wave b in FIG. 3 is varied depending on the polarity of the speed difference signal r and the pulse width. That is, if the horizontal synchronization signal c is later than the reference signal a, the length of time t is increased according to the degree, and if it is ahead, the trapezoidal wave generation circuit is controlled to be shorter according to the degree. .

The position where the horizontal synchronous signal (c) samples the trapezoidal wave (b) in the locked state is not constant as in the locked state, but gradually moves as if the trapezoidal wave is added. As a result, the disk drive motor to which the sample value is supplied has a waveform whose waveform is a trapezoidal waveform, and the voltage waveform whose frequency is the frequency of the difference between the frequency of the horizontal synchronization signal c and the frequency of the reference signal a. This state becomes equivalent to the one applied.

At this time, as described above, if the horizontal synchronizing signal (c) is later than the reference signal (a), the duration t of the trapezoidal wave (b) is lengthened, so that the average value of the voltage applied as a whole to the motor side is increased. As a result, the rotation speed of the motor is increased, so that the horizontal synchronizing signal c can enter the locked state following the reference signal a.

If the horizontal synchronous signal (c) is ahead of the reference signal (a), it is to shorten the duration of the trapezoidal wave (b). Therefore, the average value of the voltage applied to the motor is lowered. Is delayed so that the reference signal (a) can enter the locked state following the horizontal synchronization signal (c).

The operation principle of the present invention will be roughly understood from the above.

The following describes an embodiment of the present invention with reference to the drawings.

1 is a block diagram showing an embodiment of the present invention. In the same figure, a reference frequency power supply is connected to the terminal 1. The reference signal a from the power supply is connected to the trigger terminal of the monostable multivibrator 2 and to the input terminal of one of the phase control detector 3 of the edge control digital memory type. The terminal 4 is connected with a horizontal synchronous signal c reproduced on the disc. This signal is connected to the control terminal of the sample hold circuit 5 and to the other input terminal of the phase difference detector 3. The output of the phase difference detector 3 is input to a phase compensation circuit 6 including an integral element and smoothed to a voltage according to the output pulse width of the clothes difference detector 3, the output of which is via the resistor 7. It is connected to the resistance 9 of the vibrator 2 and the connection terminal of the capacitor 8.

The capacitor 8 and the resistor 9 are connected toward the power supply as an element for determining the time constant of the multivibrator 2. The output of the monostable multivibrator 2 is connected to the control terminal of the switch 10, and the switch 10 is opened when there is an output of the multivibrator 2.

In addition, 11 is a constant current source, this output is connected to the capacitor | condenser 12, and the capacitor | condenser 12 is charged, and the inclined surface of trapezoidal wave b is formed. It is also connected to the power supply via the diode 13. Therefore, the upper edge of the trapezoidal wave b is determined by the power supply voltage to which the diode 13 is connected. The output of the constant current source 11 is connected to the switch 10 described above. When the switch is turned on, the capacitor 12 discharges and the trapezoidal wave is reset.

The trapezoidal wave formed in this way is sent to the buffer 14 for impedance conversion, the output is sent to the sample-hold circuit 5, and this output is the speed and phase difference detection output in the output terminal 15. That is, the sample hold circuit 5 samples the voltage of the trapezoidal wave b at the arrival of the horizontal synchronous signal c and holds the voltage for the period until the arrival of the next horizontal synchronous signal c. It outputs to the terminal 15.

In the following device, the horizontal synchronization signal arrival position (sample position of the sample holding circuit 5) in the locked state of the reference signal a and the horizontal synchronization signal c is near the center of the trapezoidal wave b. The trapezoidal wave (b) is configured to be locked at the midpoint potential near the upper and lower sides. Although it has already been understood, the block M is a trapezoidal wave generating circuit, the block p is a speed difference detecting circuit, and the monostable multivibrator 2 is a trapezoidal wave generating control circuit for controlling the starting stop of the trapezoidal wave generating circuit M. That is, when the waveform relative to each part is explained with reference to FIG. 3, when the output (wh) of the monostable multivibrator 2 is at the low level, the switch 10 is closed and the trapezoidal wave b is reset to the GND level. The lower side of the trapezoidal wave is formed in the same manner as in the periods t _{a to} t _b in FIG. Next, when the monostable multivibrator 2 is triggered by the rising edge of the reference signal a of the reference frequency power source (Fig. 3 time t _b ), a pulse (high level) is output from the monostable multivibrator 2; When the switch 10 is opened and the electric charge is charged to the capacitor 12 at full current by the constant current source 11, the trapezoidal wave b is in the period t _a to t _{c shown} in FIG. It becomes an inclined wave having an inclined surface as shown in FIG. The end time t _c of the slope is such that the voltage of the trapezoidal wave b exceeds the sum of the power supply voltage + Vcc (> 0) connected to the cathode side of the diode 13 and the forward voltage drop V _p of the diode 13. The lower surface of the diode 13 is turned on and the trapezoidal wave b is clamped at + Vcc + Vp to become a single voltage as in the period of t _{c to} t _a 'in FIG. When the pulse output from the monostable multivibrator 2 ends at time t _a ′, the switch 10 is turned ON again to discharge the electric charge charged in the condenser 12. Therefore, the trapezoidal wave b causes the GND level to decrease. It descends toward and resets. As described above, this reset period is continued until the pulse is output from the monostable anchovy vibrator 2 by the edge of the reference signal a of the reference frequency power supply 1 and the switch 10 is turned on. In this way, the operation is repeated by the reference signal a of the reference frequency power source 1.

Therefore, block M in FIG. 1 is a trapezoidal wave generating circuit in which a tetragonal wave is obtained by appropriately turning on and off the switch 10. Here, the ON / OFF of the switch 10 is controlled by the monostable multivibrator 2, and the pulse of the monostable multivibrator 2 is output (wh) (high level) and the trapezoid of the trapezoidal wave b is inclined. The monostable multivibrator (times t _b , t _b ', etc. of FIG. 3) is started, and is passed through _a constant voltage period (times t _c- t _a ' of FIG. 3) on the upper side of the trapezoidal wave b in the middle. The output of 2) (the monostable multivibrator 2 controls the trapezoidal wave generator circuit M to lower the trapezoidal wave at the same time as the unpulse ends. The duration t (the upper side of the trapezoidal wave b) is controlled. The period of t _{c to} t _a ′ in FIG. 3 is the same as the slope of the inclined portion (FIG. 3; the period of t _{b to} t _c , etc.), and the power supply voltage connected to the cathode side of the diode 13 is constant. It is determined by the pulse width of the output c of the stable multivibrator 2 (phase difference using conventional tetragonal wave) In the detection generation circuit and the control circuit, the pulse width of the monostable multivibrator 2 is fixed, and the time t of the upper side of the trapezoid is constant).

Next, the circuit operation will be described. When the phase lock is applied, the voltage as the detection output at the output terminal 15 is shown by holding the instantaneous voltage (see Si in FIG. 3) of the inclined plane of the trapezoidal wave coinciding with the phase of the horizontal synchronization signal c. .

If the phase lock is shifted, as described above, the relative phases of the horizontal synchronizing signal (c) and the trapezoidal wave (b) are shifted with time, and thus the horizontal synchronizing signal (c) is shifted at a constant speed. The waveform similar to the trapezoidal wave appears at the output terminal 15 by the frequency of the difference between c) and the trapezoidal wave b.

Therefore, the average value of the output voltage is equal to the average voltage of the original trapezoidal wave. Next, a state in which the average value (average voltage of the trapezoidal wave appearing on the output terminal 15) is controlled by the output of the speed difference detection circuit p will be described with reference to FIG.

In FIG. 2, the waveform a is a reference signal from the reference frequency power supply, as is already clear, and the monostable multivibrator 2 is triggered by this leading edge. The output pulse width of the vibrator 2 is usually determined by the resistor 9 and the capacitor 8, but is determined by the resistor 9 and the capacitor 8 in the present circuit, but also by the resistor 7 in the present circuit. Is connected.

Therefore, since the charging speed of the capacitor 8 is changed by the voltage of the resistor 7, that is, the phase compensating circuit 6, the output pulse width of the monostable anchovy vibrator 2 is also changed (phase compensating circuit 6 When the output voltage of) increases, the pulse width decreases.

When the output of the phase compensating circuit 6 is high in the output waveform m of the monostable annealing vibrator 2, the output pulse width is close to t ₁ , and in the low case, the output pulse width is close to t ₂ . The trapezoidal wave b starts rising by raising the output pulse k of the monostable multivibrator 2, and the trapezoidal wave b also drops by falling. In this case, the average voltage of the trapezoidal wave b changes as shown by the pulse widths of the output pulses (wh) of the monostable multivibrator _{2 in} the case of t _{2 and} the case of t ₁ .

Therefore, when the phase lock is not applied, the output of the phase compensating circuit 6 rises and falls by the speed control capability of the phase control circuit of the predictive control digital memory type, and as a result, the average voltage of the trapezoidal wave b is also increased. Since the average value of the speed phase difference output voltage in the output terminal 15 rises and falls as well, it rises and falls, so that the speed control of the disc drive motor can be easily and accurately performed even when the CLV disc is reproduced, thereby realizing a phase goke.

As described above, according to the present invention, the speed control reference of the disc drive motor is taken as a reference signal coming in at a predetermined period. Therefore, the speed control is not affected by the speed error during disc recording, and when the phase lock is applied, the influence of the speed control is applied. Since it does not receive, there is an advantage that no adverse effect as a side effect does not appear regardless of the use of a speed control circuit which is weak against noise.

Claims (1)

A control apparatus for controlling the drive motor of the disc to match the rotational speed and the rotational phase of the disc in the video disc player to the reference value 1, respectively, wherein the trapezoidal wave generating means and the trapezoidal wave generating means are started by predetermined operation. After the operation duration of is controlled by the control circuit by a trapezoidal wave generation control circuit (2, 8, 9) for resetting the means, and a synchronization signal (4) which is generated periodically in synchronization with the rotation of the disc. A sample and hold circuit (5) for sampling and holding the trapezoidal wave repeatedly output from the generating means, a phase detection circuit for detecting a speed difference and a phase difference between the reference signal and a synchronization signal, and the trapezoidal wave in accordance with the detected phase difference Control means (7) for variably controlling the length of a predetermined operation duration in the control bulletin; The rotation speed control device of the status of the disk to the sample values characterized in that the driving motor, so as to supply as a control signal.

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