JPH05166292A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE:To steplessly and linearly control the gain of a spindle servo. CONSTITUTION:A horizontal synchronizing signal B read out of an optical disk 1 is compared with a reference synchronizing signal A in phase by a phase comparator 7, and its output is sent to a phase error voltage generating circuit 22. An output corresponding to phase lead and lag from the phase comparator 7 is converted into a positive or negative pulse signal based on a reference level and is outputted by the phase error voltage generating circuit 22. The reference level of the output pulse of the phase error voltage generating circuit 22 is controlled via a D/A converter 13 and a buffer amplifier 14 by a microcomputer 5 based on the revolving speed, kind and size, etc., of the optical disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing device, and more particularly to an optical disc reproducing device which enables optimum control by control of a spindle servo gain without a break.

[0002]

2. Description of the Related Art In a conventional optical disc reproducing apparatus, as a spindle servo gain control and switching method, there are (1) a method of inserting an attenuator in a servo loop and using a switch or the like, and (2) phase. A method of dividing the frequencies of the synchronization signal and the reference signal at the time of comparison was used.

[0003]

However, the above-mentioned method has the following drawbacks. In the above method (1), the number of attenuators and switches increases as the number of gain changes increases. In the method of (2) above, due to the frequency division, switching can only be performed at intervals of 6 dB, and arbitrary setting is impossible.

It is an object of the present invention to provide an optical disc reproducing apparatus which enables optimum control by stepless control of the spindle servo gain and which does not require an additional attenuator or the like and has a simplified circuit configuration. ..

[0005]

The optical disc reproducing apparatus of the present invention comprises a phase comparator 7 as a phase comparing section, a phase error voltage generating circuit 22 as a phase error voltage generating section, and
It is characterized by including a microcomputer 5 as a control unit, a D / A converter 13 and a buffer amplifier 14.

[0006]

In the optical disc reproducing apparatus having the above structure, the phase comparator 7 compares the phase of the synchronizing signal read from the optical disc 1 with the reference synchronizing signal and sends the output to the phase error voltage generating circuit 22. The phase error voltage generation circuit 22 converts an output according to the advance or delay of the phase from the phase comparator 7 into a positive or negative pulse signal with respect to the reference level, and outputs the pulse signal. Based on the number of revolutions of the optical disc 1, the type and size of the optical disc 1, the microcomputer 5 passes through the D / A converter 13 and the buffer amplifier 14 and outputs the reference level of the output pulse of the phase error voltage generation circuit 22 (positive or negative pulse Level).

Thus, the gain of the spindle servo can be controlled steplessly and linearly, and is always optimum for the change of the gain from the inner circumference to the outer circumference of the optical disk 1 in the CLV (constant linear velocity system) servo. It can be controlled. Further, when the optical disc reproducing apparatus is made into a multi-disc type, the stepless control can be similarly performed for the gain switching of the spindle servo depending on the type and size of the optical disc 1, and an attenuator or the like to be newly added is not necessary. Therefore, the circuit configuration is simplified.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an optical disc reproducing apparatus according to the present invention. FIG. 1 particularly shows one embodiment of a spindle servo system. Further, a case of a video disc player as an optical disc reproducing device is shown. In FIG. 1, reference numeral 1 denotes an optical disk (hereinafter referred to as a disk) such as a CD (compact disk) or a CDV (CD video) mounted on an optical disk reproducing device. An optical pickup 2 is controlled by a system controller (not shown).
Supplies the read signal of the disk 1 to the RF amplifier 3. The RF amplifier 3 amplifies the reproduction signal of the disc 1 and supplies it to the video demodulation circuit 4. The video (VIDEO) demodulation circuit 4 demodulates the output of the RF amplifier 3 and supplies the output to the sync separation circuit 6.

The sync separation circuit 6 takes out the horizontal sync signal B from the output of the video demodulation circuit 4 and supplies it to the phase comparator 7. The reference signal generation circuit 8 creates a reference synchronization signal A based on the output of the crystal oscillator 9 and outputs the reference synchronization signal A to the phase comparator 7. The phase comparator 7 compares the phase of the horizontal synchronizing signal B and the reference synchronizing signal A, and when the phase of the horizontal synchronizing signal B is delayed with respect to the reference synchronizing signal A, outputs the output signal C (see FIG. 2). A to C), and when the phase of the horizontal synchronizing signal B leads the reference synchronizing signal A, the output signal G
Is transmitted (A, B, G in FIG. 3).

The disc 1 mounted on the optical disc reproducing apparatus is rotated by a spindle motor 10. The FG sensor 11 detects the number of rotations of the disk 1 and outputs information on the number of rotations to the microcomputer 5. TOC information of CD and CDV is input from the RF amplifier 3 to the microcomputer 5 via the digital signal processing circuit 12. Further, the Phillips code (absolute time) of the video disc is input from the video demodulation circuit 4 to the microcomputer 5. The spindle servo lock detection circuit 39 detects the spindle servo lock time based on the output of the phase comparator 7 and outputs it to the microcomputer 5.

Here, the microcomputer 5 distinguishes the type and size of the disk 1, CLV (constant linear velocity system), CAV (constant angular velocity system), and the number of revolutions in CLV based on the above-mentioned input information. And the optimum gain control signal is sent to the DC level analog voltage Vcon [V] via the D / A converter 13 and the buffer amplifier 14.
Output as.

Buffer amplifier 14 and phase comparator 7
And the circuit configuration between the phase compensation circuits 15 will be described. The output end of the buffer amplifier 14 is grounded via the resistors 16 and 17. The output end of the buffer amplifier 14 is grounded via the switch 18 and the switch 19. The connection point 24 between the resistors 16 and 17 is connected to the switch 18
Are connected to the connection point 25 of the switch 19. The output end of the buffer amplifier 14 is grounded via the resistors 20 and 21. The connection point between the resistor 20 and the resistor 21 is
It is connected to the positive input terminal of the differential amplifier 28. here,
The resistors 16 and 17 and the switches 18 and 19 form a phase error voltage generation circuit 22. The resistors 20 and 21 form a voltage dividing circuit 23. The resistors 16 and 17 have the same resistance value, and the resistors 20 and 21 have the same resistance value.

The connection point 24 is connected to the negative input terminal of a differential amplifier 28 via resistors 26 and 27. The connection point between the resistor 26 and the resistor 27 is grounded via the resistor 29 and the capacitor 30. The connection point between the resistors 26 and 27 is grounded via the capacitor 31. Resistance here 29
The capacitors 30 and 31 form an integrating circuit 32.

The negative input terminal of the differential amplifier 28 has a resistor 33,
It is grounded through 34. The negative input end of the differential amplifier 28 is connected to the output end of the differential amplifier 28 via the capacitor 35. The negative input terminal of the differential amplifier 28 is connected to the output terminal of the differential amplifier 28 via the resistors 33 and 36. The negative input terminal of the differential amplifier 28 is grounded via the resistors 33 and 37 and the capacitor 38.

Next, the circuit operation between the buffer amplifier 14, the phase comparator 7, and the phase compensation circuit 15 will be described with reference to FIGS. 2 to 4 are timing charts of the main part operation in the spindle servo system of FIG. Output voltage Vc of buffer amplifier 14
on [V] is divided by the resistors 16 and 17, the voltage at the connection point 25 becomes (1/2) Vcon [V], and the reference voltage of the output signal of the phase error voltage generation circuit 22 is (1/2).
It becomes Vcon [V].

As shown in FIG. 2, when the phase of the horizontal synchronizing signal B is delayed with respect to the reference synchronizing signal A, the phase comparator 7 controls the switch 18 by the output signal C and turns on the switch 18. .. However, the phase comparator 7 outputs the output signal G
(See FIG. 2), the switch 19 is in the off state. As a result, the signal at the connection point 25 becomes D shown in FIG. 2, and the amplitude is (1/2) Vcon [V] (Vcon- (1/2) V with (1/2) Vcon [V] as the reference level.
con [V]) pulse signal.

As shown in FIG. 3, when the phase of the horizontal synchronizing signal B leads the reference synchronizing signal A, the phase comparator 7 controls the switch 19 by the output signal G and switches 1 to 1.
Turn 9 on. However, the phase comparator 7 outputs the output signal C
(See FIG. 3), the switch 18 is in the off state. As a result, the signal at the connection point 25 becomes H shown in FIG. 3, the amplitude is (-1/2) Vcon [V] (GND- (1/2)) with (1/2) Vcon [V] as the reference level. V
con [V]) pulse signal. GND is here
It is ground potential.

As shown in FIG. 4, the phase comparator 7 operates when the reference sync signal A and the horizontal sync signal B are in phase with each other.
The output signals C and G (see FIG. 4) are not transmitted. For this reason,
Both the switches 18 and 19 are open (turn off). As a result, the signal at the connection point 25 becomes L shown in FIG. 4, and becomes the reference level (1/2) Vcon [V].

From the above, the output of the phase error voltage generating circuit 22, that is, the pulse signal D of FIG. 2 or the pulse signal H of FIG. 3 is integrated by the integrating circuit 32. The output of the integrating circuit 32 is supplied to the negative input terminal of the differential amplifier 28. On the other hand, the positive input terminal of the differential amplifier 28 is supplied with the voltage-divided output (1/2) Vcon [V] of the resistors 20 and 21. The reference level at the negative input terminal of the differential amplifier 28 is level-shifted to the GND level. The output signal of the differential amplifier 28 drives the spindle motor 10 via the phase compensation circuit 15 and the driver 40. Here, the output signal of the differential amplifier 28 is
At the DC (direct current) level, the voltage is proportional to (1/2) Vcon [V], and the gain of the spindle motor servo is set in an arbitrary and stepless manner by the control voltage Vcon [V] (output voltage of the buffer amplifier 14). can do.

In this embodiment, a video disc reproducing device (video disc player) is used as the optical disc reproducing device, so that a video disc is used, but the present invention is not limited to this. Instead, for example, in FIG. 1, the video demodulation circuit 4 is replaced with analog signal processing, and is replaced with digital signal processing, whereby a CD can be used instead of a video disk.

In this embodiment, the microcomputer 5 discriminates the size of the disc 1 based on the TOC information from the digital signal processing circuit 12, but the present invention is not limited to this, and disc size discrimination It is also possible to newly provide this sensor and input the output of this sensor to the microcomputer 5 to determine the disc size. In this case, a spindle servo lock detection circuit 39 as shown in FIG. 1 is used as a sensor for disc size determination, the time until the spindle servo locks is detected, and this is input to the microcomputer 5 to determine the disc size. You may decide. Alternatively, the disc size may be discriminated using a skew sensor and input to the microcomputer 5 in FIG.

Further, in this embodiment, the FG sensor 1
1, the number of revolutions of the disk 1 is detected, and the information on the detected number of revolutions is input to the microcomputer 5.
The present invention is not limited to this, and in FIG.
The output of the G sensor 11 may be input to the F / V converter (frequency / voltage converter) and the output thereof may be input to the buffer amplifier 14. In this case, the gain control based on the rotation speed of the CLV of the disk 1 can be performed without using the microcomputer 5.

Further, in the present embodiment, when the gain of the spindle servo is switched according to the type of disk,
It is advisable to provide a disc type discrimination sensor separately and input to the microcomputer 5.

[0024]

As described above, according to the optical disk reproducing apparatus of the present invention, the following effects can be obtained. (1) The control unit arbitrarily controls and varies the reference level of the output pulse of the phase error voltage generation unit based on the number of rotations of the optical disc, the type and size of the optical disc, and the like, thereby continuously changing the gain of the spindle servo, And it can be controlled linearly. Therefore, it is possible to always perform optimum control with respect to the change in the gain from the inner circumference to the outer circumference of the optical disk in the CLV (constant linear velocity method) servo. (2) When the optical disc reproducing apparatus is made into a multi-disc type, stepless control can be similarly performed for the gain switching of the spindle servo for the difference in the type and size of the optical disc, and a new attenuator or the like is not required. Therefore, the circuit configuration is simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical disc reproducing apparatus according to the present invention.

FIG. 2 is a timing chart of a main part operation in the spindle servo system of FIG.

FIG. 3 is a timing chart of an operation of a main part in the spindle servo system of FIG.

FIG. 4 is a timing chart of a main part operation in the spindle servo system of FIG.

[Explanation of symbols]

 1 Disc 2 Optical Pickup 5 Microcomputer 7 Phase Comparator 10 Spindle Motor 11 FG Sensor 13 D / A Converter 14 Buffer Amplifier 22 Phase Error Voltage Generation Circuit 28 Differential Amplifier

Claims (3)

[Claims] 1. An optical disc reproducing apparatus for reproducing an optical disc, comprising a spindle motor servo system, and a phase comparing section for phase-comparing a synchronization signal read from the optical disc with a reference synchronization signal and transmitting an output, said phase A phase error voltage generation unit that converts the output according to the phase advance or delay from the comparison unit into a positive or negative pulse signal with respect to the reference level and outputs the same, and a reference level of the output pulse of the phase error voltage generation unit. An optical disc reproducing apparatus comprising: a control unit for controlling the optical disc. 2. The optical disc reproducing apparatus according to claim 1, wherein the control unit controls the reference level of the phase error voltage generating unit according to the number of rotations of the optical disc. 3. The optical disc reproducing apparatus according to claim 1, wherein the control unit controls the reference level of the phase error voltage generating unit based on the size of the optical disc.