JPS6182333A - Drop-out controller of optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of track jump in case of oscillation by comparing an envelope in the total reflection side of an RF signal with a reference potential to generate a drop-out control signal. CONSTITUTION:The envelope in the total reflection side of the RF signal from an optical pickup is detected without cutting by a peak holding circuit 4'. This detected signal is compared with a reference potential, which is lower than the output potential for reproducing of a total reflection face of the pickup and is higher than the output potential of reproducing of a flawing face, of a reference potential output circuit 6' by a comparator 5, and the drop-out control signal is outputted from a gate 7 to a gain controller 8 only when the input potential from the circuit 4' is lower than the input potential from the circuit 6'. Thus, even if he envelope in the low reflection level side of the RF signal is changed by oscillation, the drop-out control signal is not generated, and only the drop-out signal due to signals of dirt or flaws is outputted.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a dropout control device in an optical recording/reproducing device, and particularly to a dropout control device for controlling dropout control to prevent dropout jump from occurring due to dirt or scratches on the surface of an optical disk. The present invention relates to a dropout control device in an optical recording/reproducing device.

[Technical Background of the Invention and Problems Therewith] Recently, in the field of audio equipment, digital recording and reproducing methods using PCM (pulse code modulation) technology are being adopted in order to achieve high-fidelity reproduction.

Audio equipment using this digital recording/playback method has audio characteristics that are independent of the characteristics of the recording medium, and in principle exhibits much superior characteristics compared to those using conventional analog recording/playback methods. It is known to do.

Among such digital audio systems, one that uses a disk as a recording medium is called a DAD system, and an optical system is widely used as its recording and reproducing system.

Optical disc playback devices have a variety of advanced control functions and performance not found in conventional playback devices)-1
It is required that the sum is 19 rubs.

To explain this using an example of 6 types of CDs (2:1 discs), a transparent resin disc with a diameter of 12 cm and a thickness of 1°2 has pits corresponding to digital commercial data. A disk coated with a metal thin film forming irregularities with different reflectances was coated with a CLV (constant linear velocity) method at approximately 500 to 20 Orr.

POM is rotated at a variable rotational speed, and each is reproduced in a linear tracking manner from the inner circumference side to the outer circumference side using an optical pickup containing a semiconductor laser and a photoelectric conversion element.

This disc has a rack pitch of 1.6 μm, and a huge amount of information that can be played in stereo for about 1 hour on one side is digitized and recorded in the program area (radius 25 to 58 degrees) along with address data. A table of contents (TOC) showing each song number and start address in correspondence is digitized and recorded in the lead-in area (23 to 251 m radius).

In such optical disc playback devices, a number of extremely advanced servo technologies are used in order to quickly find the desired track and pick up the micron-order information correctly without losing sight or failing to read it. ing.

Among these various servo techniques, tracking servo is employed to accurately irradiate the 1-rack with the pickup's sear beam.

In other words, the CD racks are lined up at very narrow intervals, and the number of racks reaches more than 20,000 for a disc with a playing time of 11.5 hours, and if you look at the discs microscopically, they are more or less eccentric. The reality is that it is rotating.

If you look at this from the pickup side, it means that a track with a width of 0.5 μm and a pitch of 1.6 μm is running in a meandering manner. It is necessary to precisely cover the target track.

=3= The basic operation of this tracking servo is to detect that the pit reflected signal (shaded area) is at the center position of the photodiode, and to return it when it deviates from this position. ing.

However, if there is dirt or scratches on the surface of the disk, this may be recognized as a pit and the control signal may be disturbed, and this disturbance of the control signal may cause abnormal operations such as track jumps.

Therefore, conventionally, servo gain control circuits have been used that reduce the servo gain and narrow the servo band so as not to respond to frequency bands with many scratches and dirt components.

FIG. 4 is a circuit diagram showing the configuration of a dropout control device in such a conventional optical recording/reproducing apparatus.

In the figure, 1 is a 4-split detector of an optical pickup, 2 is a signal that is the total sum of the outputs of this 4-split detector 1 (an amplifier that amplifies the RF multiplied signal, and 3 is the output signal C-
4 is a peak hold circuit that performs peak hold of the C-cut signal; 5 is a comparator that compares the output signal of the peak hold circuit 4 with the constant voltage power supply 6 and outputs a binary signal; 7 is an AND circuit which takes the logical product of this binary signal and the "'H" signal during play and outputs it to the gain controller 1 to roller 8 as a dropout control signal.

Note that the potential level of the constant voltage power supply 6 is set lower than the potential level on the RF multiplied signal total reflection side and higher than the potential level on the low reflection side.

9a and 9b are sub-beam detectors of an optical pickup, and their outputs are input to a differential amplifier 10, which supplies a tracking error signal to the gain controller 8. The gain controller 8 lowers the gain of this tracking error signal using the drop alarm 1~control signal and outputs it.

This tracking error signal drives a tracking actuator 13 via a phase compensation circuit 11 and a power amplifier 12.

The operation of this device will be explained below.

FIG. 5 shows each part (a) to 1 of the drop-out I-=1-[1-R] device in this conventional optical recording/reproducing device.
(1) is the timing chip p-1- of the signal J3j.

The RF signal (, li) output from the 4-split detector 1 of the optical pickup is input to the amplifier 2, and the signal (a > is output.

In this signal, the low frequency component is due to the eccentricity of the optical disc, and the concavities A1 and A2 of the envelope EH of the total foul level on the 1-0 side of the R[signal are caused by dirt and scratches on the optical disc surface. This is the area where the light has decreased,
RF double signal low reflection side envelope “L’s lower concavity B
indicates a portion where the beam of the optical pickup deviates from the pitch line due to vibration and the amount of total reflection light increases.

However, as shown in FIG. 6, when the beam B of the optical pickup is tracking the rows 1 to 14a of the optical disc 14, the total reflection surface and the rows 14a of the optical disc 14 alternate with each other according to the JJ law. In order to appear correctly, the envelope EHSEL on the RF multiplied signal total reflection side and low reflection side remains flat. There are scratches on the surface of the optical disc 14.
In the case of llb, the amount of reflected q4 light at the position which is originally a total reflection surface is reduced, so that a dent A is generated in the upper envelope FH of the R[ signal.

Furthermore, as shown in Fig. 7, when the beam B of the optical pickup moves to a position away from the pitch row 14a due to vibration, the beam B of the optical pickup continues along the total reflection surface. (This means that the bit string 14
The part where the amount of foul light decreases due to a is eliminated, and a depression B is created in the envelope EL below the RF multiplied signal low reflection level.

The output signal (a) of the amplifier 2 is then passed to the C-cut 1 by the capacitor 3 to obtain the signal (b), and furthermore, the envelope signal (C) on the total fault level side is changed to 1!1 by the peak hold circuit 4. It will be done.

(d) is the reference potential level of the constant voltage power supply 6. Therefore, when the potential level of the envelope signal (C) becomes lower than the reference potential level ((1)) from the comparator 5, the signal (e) of 211h is Output.

(f) is the output of "H" when the device is played, and therefore, the AND circuit 13 outputs the logical product of these "1 - control signal ((1)). The gain of the dropout control signal (g>) output from the differential amplifier 10 (h) is attenuated to obtain a control signal (i), and the phase compensation circuit 11
, are supplied to the actuator 13 via the power amplifier 12.

As is clear from Fig. 5, in such a conventional optical recording/reproducing device, the gain of the tracking error signal is adjusted when there is dirt or scratches on the optical disc surface. Although this damps the track jumps, it also lowers the gain of the tracking servo when vibrations or motions are applied, making it more likely to cause tracking errors in response to vibrations. There was a problem that

[Object of the Invention] The present invention has been made in order to address the above-mentioned problems in the conventional art.If there is dirt or scratches on the surface of an optical disc, the gain of the i~ragging~ra signal is reduced. te1
A drop in an optical recording/reproducing device that causes a rack jump when ta < t, and does not reduce the gain of the trough error signal even if there is vibration, thus preventing the rack jump from easily occurring during vibration. The purpose is to provide [1-ru locks] to Ara 1 to -1 and 1.

"Summary of the Invention" In the present invention, the envelope of the full-fault side is detected by a peak hold circuit without being cut off from the RF multiplied signal C input from an optical pickup that plays back recording on an optical disc. .

The output signal of the peak hold circuit is inputted with the output signal of this peak bold circuit to set a reference potential that is lower than the 111 force potential when reproducing the total reflection surface of the optical pickup and higher than the output potential when reproducing the scratched surface. The reference potential of the reference potential output circuit to be outputted is compared, and a drop-out I-TJ point signal is output only when the input potential from the peak hold circuit becomes lower than the input potential from the reference potential output circuit.

In addition, even if the -L envelope on the low reflection level side of the RF multiplied signal changes due to J: vibration, a door signal will not be generated, and a door signal due to dirt or scratches will not occur. ] To Zupfu 7 1 to Con 1 [1 - Only Shingetsu is output. 1 [Embodiments of the Invention] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a 4-circuit diagram showing the configuration of an embodiment of the present invention. 4I: In FIG. 1, the parts common to FIG. 4 have the same 74th f;

In the figure, 1 is the 4-minute λ11 detector of the optical pickup, 2 is the amplifier that amplifies the Rr': f8 of this 4-split detector 1, and 4' is the amplifier 1-1 on the R "all sides of the signal" level side. 1 is a circuit for detecting a peak hole. Note that 15 has a time constant that responds to the frequency of f=+H due to dirt or scratches, but does not respond to the RF multiplied signal frequency.

6' is a resistor R from the output signal of the peak hold circuit 4'.
1. It is a reference potential output circuit that creates a reference potential by dividing the resistor voltage into R2. It is a capacitor that has a time constant that responds to the frequency of the eccentric component of the disk.

7 is a comparator that compares the output potential of the reference potential output circuit 6' and the potential level of the envelope on the total reflection level side of the peak hold circuit 4'; This is an AND circuit that outputs the AND signal with the signal as a dropout control signal.

9a and 9b are sub-beam detectors of an optical pickup, and their output signals are input to a differential amplifier 10 to output a tracking error signal.

Reference numeral 8 denotes a gain controller 1 to roller, which inputs the tracking error signal of the differential amplifier 10 and a dropout control signal from the AND circuit 7 to attenuate the gain of the tracking error signal.

11 is a phase compensation circuit that compensates the phase of the tracking signal attenuated by the gain controller 8; 12 is a power amplifier that drives the tracking actuator 13;

The operation of the apparatus of this embodiment will be explained below.

FIG. 2 shows each part (A) to (
11) are timing charts 1 to 1 of the signals.

In the drive out control device of this embodiment, as shown in the figure, the output signal 53 (
A) It is input to the 4.1 peak hold circuit 4', and the envelope signal ([3) on the total reflection level side thereof is 111 processed.

Here, the dent B caused by 1 disturbance is -1- on the low reflection side.
Since it belongs to 1-Pl-L, it is output 4ffi.

This envelope signal (B) is the WtM potential output circuit 1'
Both the output signals from 86'=<C> are input to the comparator 5, and a binary signal (11) is output.

The signals (D) from the next two ships are input to the AND circuit 7, and when the "H" signal (E) is at the "H" level during play, the dropout control signal (D) is input from the AND circuit 7.
F) is output to the gain controller 8. The gain of the tracking error signal (G) from the differential amplifier 10 is attenuated by the gain controller 8 using the dropout control signal (F), and the attenuated control signal (T1) is output from the gain controller 8. This control signal (H) is supplied to the tracking actuator 13 via the phase compensation circuit 11 and the power amplifier 12, and controls the ranking actuator 13 to 1 to perform a predetermined tracking servo.

In the above embodiments, an example in which a resistive voltage divider circuit is used as the reference potential output circuit 6' has been described, but the present invention is not limited to such embodiments.
As shown in the figure, it is also possible to branch the output of the peak bold circuit 4' and use a diode 17 to lower its potential level. In the figure, reference numeral 18 is an auxiliary constant circuit that does not respond to the frequency of the signal due to dirt or scratches on the RF multiplied signal total reflection level side, but responds to the frequency of the eccentric component of the optical disc.

[Effect of the invention 1] As explained above, in the present invention, the envelope on the total reflection side of the R[signal is calculated from this envelope as a base I\
Compared to the reference potential created using the potential output circuit,
Since it is configured to generate a dropout control signal, the gain of the tracking error signal is attenuated only when there is dirt or scratches, and the gain of the tracking error signal is not attenuated to 1 during vibration, which is good. It is possible to perform a simple transaction.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
, FIG. 3 is a circuit diagram showing another example of the reference potential output circuit used in the present invention, FIG. 4 is a circuit diagram showing the configuration of a dropout control device in a conventional optical recording/reproducing device, and FIG. Figure IJ: Is there a timing diagram that shows the +/- signals for each part? -1., Figure 6 is a diagram to explain the situation in which a dent Δ occurs in the envelope on the total reflection side of the RF multiplied signal due to dirt or scratches on the optical disc surface, and Figure 7 is a diagram to explain the situation in which a dent Δ is caused by the vibration of the optical disc. FIG. 1 is a diagram for explaining a situation in which a dent B occurs in the envelope on the low reflection side of the RF multiplied signal. 1......4-split detector 2...
......Amplifier 3.15.16...Capacitor 4.4'...Peak hold circuit 5...Comparator 6... ...... Constant voltage circuit 6'...
...Reference potential output circuit 7...
AND circuit 8...Gain controllers 9a, 9b...Sub beam detector 10...
......Differential amplifier 11...
. . . Phase compensation circuit 12 . . . Power amplifier 13 . . . Tracking actuators 1 to 17 . . .・・・Diode 18・・・・・・・・・ Time constant circuit agent Patent attorney Sa Suyama - Figure 5 Figure 6 Figure 7 - [33 (Yaw ζri n-

Claims (1)

[Claims] There is a peak hold circuit that inputs the RF signal output from the optical pickup that plays back the recording on the optical disc and outputs the envelope on the total reflection side, and a peak hold circuit that inputs the output signal of this peak hold circuit to input the RF signal output from the optical pickup to play back the total reflection surface. A reference potential output circuit outputs a reference potential that is lower than the output potential of the circuit and higher than the output potential during regeneration of a dirty or scratched surface, and the output signal potential of the peak hold circuit is compared with the reference potential to determine the peak. 1. A dropout control device for an optical recording/reproducing device, comprising a comparison circuit that outputs a dropout control signal when the potential of the output signal of the hold circuit becomes lower than a reference potential.