JPS59152548A - Disk record reproducer - Google Patents

Abstract

PURPOSE:To stop quickly the movement of a pickup when a track jump is over and to apply the tracking servo by producing a signal having a level approximately between plus and minus pole voltage peak level signals of a tracking error signal and adding this signal to the tracking error signal after inversion of polarity. CONSTITUTION:The plus and minus polarity peak detecting circuits 25 and 26 detect the plus and minus voltage peak levels of a tracking error signal T respectively and produce plus and minus voltage peak level signals V+T and V-T. These signals are supplied to a mixer/adder circuit 27 via buffer amplifiers IC2 and IC3 and resistances R6 and R7. In this case, a differential amplifier IC1 and a negative feedback resistance R8 produce the voltage signals having the value between both voltage levels and add these signals to the signal T after inversion of polarity. Then a tracking error signal (T+DELTAT) having the compensated offset voltage. A switching signal L is stopped after the track jump is over, and a switch S is turned off. At the same time, a tracking servo circuit 20 performs immediately and assuredly the tracking servo to the desired pit train since the plus and minus voltage control regions of the signal (T+DELTAT) are equal to each other.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a CD (optical compact disc), for example.
(Digital Audio Disc)
The present invention relates to a disk record reproducing device suitable for use in other applications, and particularly to one that can completely stop the movement of the pickup immediately after the pickup finishes jumping into a track and perform tracking servo.

[Technical background of the invention]

Recently, in the field of audio equipment, a digital recording and playback method using PC'1V1 (pulse code modulation) technology is being adopted in order to achieve high-fidelity playback as much as possible. In other words, this is what is called digital audio, and the audio characteristics do not depend on the characteristics of the recording medium and are much superior to those using conventional analog recording and playback methods. This is because it is established in principle.

In this case, a system that uses a disk as an H1 recording medium is called a DAD system, and the recording and reproducing methods proposed include optical, electronic, and mechanical. Regardless of which method is adopted, the regeneration device that embodies it must be able to satisfy the control function and performance of the ridge tubercity, etc., which are not found in conventional methods. ing.

In other words, if we take the CD system as an example,
CI, a disk made of a transparent resin disk with a diameter of 12 ctn and a thickness of 1.2 hazy, coated with a metal thin film that forms pits (irregularities with different reflectances) corresponding to digital (1-'CM) data. 'V (constant linear velocity) method approximately 5
It is rotated at variable rotational speeds of 00 to 200 r, p, and m, and is reproduced in a linear tracking manner from the inner circumference 911j to the outer circumference (Ml+) using an optical pickup incorporating a semiconductor laser and a light dragon element. However, the track pitch of this disc is 1.6 μm, and a huge amount of information is recorded in the program area (radius of 25 to 58 μm), which can perform stereo playback for about one town. This can be easily determined from the fact that their inch statuses are recorded in the lead-in area (23rd to 25th radius).

By the way, what is particularly important in the above-mentioned C1) type disc record playback device is that in order to clearly read out the digitized data recorded on the disc, the light beam irradiated from the pickup does not reach the pits of the disc. Tracking error control (tracking servo) is applied to accurately trace the pit row without deviating from the row, that is, without causing a tracking error.

Figure 1 shows a conventional tracking servo means.
The reference numeral 11 in the figure is a disk, on one side of which a pit row is recorded. A pickup 12 is provided below the disk 11 in the figure. This pickup 12 is movable in the radial direction of the disk 11 by a pickup feed motor (not shown). This pickup 12 includes an objective lens 13 and a moving coil 15 for moving the objective lens 13 in the tracking direction (radial direction of the disk 1) 14 in cooperation with a magnet (not shown). Semiconductor laser 16. It consists of a beam splitter 17, a photoretractor 18, and the like. The objective lens 13 is irradiated with a light beam emitted from a semiconductor laser 16 via a beam splitter 17. Therefore, the above-mentioned light beam is focused (spot) on the signal distribution surface of the disk 11 by the objective lens 13, and is reflected depending on the presence/absence of the upper row of the disk 11.5This reflected light is The objective lens 13 is reversed and the beam splitters 1 and 7 are
The light is reflected at a right angle by the light beam and is received by the photodetector 18.

Here, the photodetector 18 is, for example, as shown in FIG. 2, four detection areas PL)a-PDd made of photodiodes etc. are arranged point-symmetrically.
This is a so-called four-part type. Same, arrow A-A in the figure
- corresponds to the tracking direction of the bit string, and arrow B-B corresponds to the tangential direction of the pit string.
The detection wandering areas PDa-PDd are arranged with the dividing lines aligned at B. The detection areas PDa to PDd respectively receive the reflected light and supply signals Pa to Pd, which compare frequency characteristics with the presence or absence of bits, to a data demodulation circuit and a focus servo circuit (not shown). It is also connected to the tracking error signal generation circuit 19.

This tracking error signal generation circuit 19 operates in a detection area P located at a diagonal position 3 of the photodetector 18.
It detects the difference in the amount of received light between Da, PDc, PDb, and PDd. That is, the tracking error signal generation circuit 19 generates (Pa+
A signal Pc)-(Pb+Pd) is generated, and the signal is changed into a voltage level change through a low-pass filter (not shown). This voltage signal is then output as a tracking error signal '9F corresponding to the deviation of the optical beam spot in the forward and reverse directions (tracking error) with respect to the pit row of the disk 1.

That is, as shown in FIG. 3, for example, this tracking error signal 'P is at level 1b of O[V] when the spot of the light beam is correctly positioned on the pit row P, and the spot on the pit row P is Corresponding to the positional deviation in the positive and reverse directions, positive and negative voltages 1h are output. This tracking error signal 'r is supplied to the front Me moving coil 15 through a tracking servo circuit 20'ff consisting of a phase compensation circuit, an amplifier circuit, etc., so that the spot is always positioned correctly on the bit string P. The objective lens 13 is controlled in this manner, and tracking servo is applied thereto.

The tracking servo during disk playback has been explained above, but in this type of TisfRecord Toyonaka device, for example, any data part can be quickly selected from the digitalized data recorded on the disk 11. search), move the pickup 12 to the disk 1.
The so-called spot, which moves at high speed in the radial direction of 1))
, uh, yeah. In Figure 1, 21 is the system controller, i&11, t
It is composed of a microcomputer, and controls the trough operation of the disc record reproducing device and the various display threads, etc., in a comprehensive manner by operating commands from a keyboard (not shown) or the like.

And now, on the above keyboard, time 11 in Figure 4 is pressed.
When a track jump operation command (which includes target address information indicating the portion of the disk 11 where the target data to be selected is recorded) is issued,
The system controller 21 first outputs a cutting blade signal as shown in FIG.
4 (b
) Generates a track jump signal as shown in ().

Here, the system controller roller 21 moves the pickup 12 to the disk 1 based on the target address information input to the keyboard section and the current address information obtained from the pit row currently being played by the pickup 12.
In addition to calculating all movement direction information such as whether to move the pickup 12 toward the outer circumference or toward the inner circumference,
Calculate distance information to move.

The moving direction information and distance information are then supplied to the track jumping signal generation circuit 22 as a front S pit track jumping command signal.

Then, based on the moving direction information signal, the track jumping signal generating circuit 22 has a positive polarity (first polarity) when moving the pickup 12 toward the outer circumference of the disk 11, and a negative polarity (first polarity) when moving the pickup 12 toward the inner circumference. As shown in Fig. 4 (Cb), the smooth mill outputs a voltage signal having positive polarity). This voltage signal is supplied to the tracking servo circuit 20 as a track jumping signal.

In this tracking servo circuit 2o, the tracking error signal T is cut off to turn off the tracking servo in response to a warning signal from the system controller 21, and the track jump signal generation circuit 22
outputs the track jump signal supplied from f4'
lJH is supplied to the moving coil 15. Therefore, the objective lens 13 is moved toward the outer circumference of the disk 11, and accordingly, the forward bending pickup feed motor is rotated to move the pickup 12 toward the outer circumference of the disk 11. The pit row is moved at both speeds in the direction of the pit row, and only the spot track can be enjoyed.

Here, when the pickup 12 is moved quickly in the direction of the outer circumference of the disk 1 as described above, the spot crosses the pit row of the double track, so that the tracking error signal T becomes as shown in FIG. 4 (c). It is output as a continuous AC waveform as shown in the figure. However, since the tracking error signal T having an AC waveform is cut off within the tracking servo circuit 20 as described above, it is not supplied to the moving coil 15, that is, it is not provided to the tracking servo.

The tracking error signal T is sent to the counter circuit 2.
3, and the OCV) level crossing points at that time of inclination are counted. In other words, counting the 0 [V] level crossing points of the tracking error signal means counting the number of pit rows that the spot crosses, and as mentioned above, this means that the track pitch is 1. .6 [μm], it means that the distance traveled by the super-station pickup 12 on the disk 11 is determined.

If the moving distance of the pickup 12 served by the counter circuit 23 matches the distance information calculated by the system controller 21 at time t3 in FIG. 4, the system controller 21 receives the truck jumping command signal. As a result, the truck jumping signal 1G generation circuit 22 stops generating the truck jumping signal (that is, becomes 0 level), and the movement of the pickup 12 is stopped. At this time, the system controller 21 also stops generating the cutting signal, returns the tracking servo circuit 20 to a state corresponding to the reproducing operation, and outputs the tracking error signal T supplied to it by 9u. The tracking servo described above is performed based on the tracking error signal T.
This is what you do.

Here, as shown in FIG. 4 (1)), trunk 1ζ
The intrusion signal is inverted to negative polarity at time 12, which is about the middle of time i, 1 to 13. The scary thing is the time
11 to 12, the pickup 12f is accelerated toward the outer circumferential direction of the disk 11, and from time i2 to 1
By applying braking to the acceleration force between 3 and 3,
Pick up 1 at target position <W (corresponds to time bottle 3)
2. It is designed to stop the vehicle in a completely safe manner. Then, at the time j2id at which the polarity of this truck jumping signal is to be reversed, the pickup 12 moves its entire distance (from time 11 to 1
(corresponding to 3) is calculated and supplied to the truck jumping signal generation circuit 22 as a front jump truck jumping command signal.

[Problems with background technology]

However, in the conventional disc record playback device as described above, due to variations in the structure of the pickup 12, even though the spot is correctly positioned on the pit row, the reflected light at that time is There is an unbalanced irradiation to the two detection areas PI)a, PDd and PDb, PDc arranged in the bit row tangent direction (arrow B-B') of the protector 18.

In such a disc record playback device, the tracking error signal 'P' shows the following:
A peak level difference occurs between the positive voltage region and the negative voltage region with respect to the 0 [■] level of the tracking servo signal T, and a difference occurs in the control range of the pit row in the forward and reverse directions.

DC for tracking error signal 'V as above
The appearance of the offset tortoise voltage also occurs when the pickup 12 is moved at both speeds in the radial direction of the disk 11 because the objective 8 lens 13 is biased in the forward or reverse direction during the movement. . Although such an offset voltage level poses almost no problem during playback, it is generated at a large level when the pickup 12 moves at high speed, so that the target bit string cannot be detected as shown in FIG. If the number of 10,000 control regions needed to draw the spot becomes significantly larger than the other control region. Therefore, when the search operation ends at time t3 shown in Fig. 4 and the tracking servo is turned on, the spot is pulled toward the pit row P, but the 7IO connected energy is transferred in the opposite direction. It cannot be absorbed completely in the dividing ranges 14 to 15 for drawing in, and ends up entering the control area of the bit string Q adjacent to the target pit string P.

Then, in the same way, in the pit string Q, the -10,000 control regions t6 to t7 are larger than the other control regions 17 to 18, so they also exceed the divided part j region of the bit string Q, and in the end, the spots continue to pass through the pit rows one after another. As a result, the pickup 12 is stopped at a position considerably deviated from the target bit string P.

For this reason, accurate search operations cannot be performed.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks, and to provide a disc record reproducing apparatus til, which can quickly stop the movement of the pickup when the pickup finishes jumping into the track and perform tracking servo.

[Summary of the invention]

That is, the disc record playback device according to the present invention has the following features:
a peak detection circuit that receives a tracking error signal in response to generation of a track jump command and generates a positive voltage peak level signal and a negative voltage peak level signal of the tracking error signal; and a positive voltage output from the peak detection circuit. Level signal generating means for generating a signal having a level approximately equal to that of the peak level signal and the negative voltage peak level signal; and a level signal generating means for generating the tracking error signal by inverting the pole a' of the signal obtained by the level signal generating means. %* indicates that the DC offset of the front-position tracking error signal in the state of jumping into the track is corrected by the equal amount of the tortoise pressure.

[Embodiments of the invention]

Hereinafter, the features of this invention will be explained with reference to the drawings. In FIG. 5, the same parts as in FIG. 1 are designated by the same reference numerals, and only the different parts will be explained here. That is, the tracking error signal T output from the tracking error number 1g generation circuit 9 is connected to the resistor R1,
The level compensation circuit 24 consisting of R2 is supplied to the non-inverting input terminal ((1) of the differential product ICI), and is also supplied to the resistor R3 after removing the switch S. is turned on and off by a switching signal from the system controller 21.

The tracking error signal T supplied to the resistor 1 (a) is transmitted through the diode D11, the capacitor Ct
+resistance i (4), and a negative polarity peak detection circuit 26 consisting of diode D21, capacitor C2, and resistor l, respectively.This positive peak detection circuit 25 detects the above-mentioned tracking error. 1
It detects the positive voltage peak level of No. 6 T (W), and this @ output positive voltage peak level signal is sent to the buffer amplifier ICz.
is supplied to resistor R6 via. Similarly, the negative polarity peak detection circuit 26 detects the negative voltage peak level of the tracking error signal T. It is supplied to resistor 7, which is set to 11v, equivalent to R8. The positive voltage and negative voltage peak level signals obtained through the resistors 1(6, l(y) are added together and supplied to the inverting input terminal (→) of the differential amplifier ICI.

This differential amplifier ICI constitutes the mixed addition circuit 27 together with the negative feedback resistance ratio 8 and the resistance 1 (1, R2) of the level compensation circuit 24 written in bIJ. )(,8
= 21 (set to 6, and still level compensation circuit 2
It is assumed that the resistors R1 and R2 of No. 4 are set so that 几1=1 (+2).Then, the mixing addition circuit 27 is
For the tracking error signal T supplied to the non-inverting input terminal (A) of the differential amplifier ICI, the inverting input terminal (A)
→The tracking servo circuit 20 adds and inverts the addition signals of the positive voltage and negative voltage peak level signals supplied to the tracking servo circuit 20.
This is what is output to.

The operation of the above configuration will be explained below.

First, when a track jump command is generated by the keyboard section, the Mll fjd system controller 2
1 to time i10 in FIG. 6, the switching signal shown in FIG. output to pickup 12
is moved toward the desired pit row direction.

At this time, the tracking error signal T output from the tracking error signal generation circuit 19 becomes as shown in FIG. 6(b) due to the offset voltage Vc. Also,
At the same time, the switch S is turned on, so the tracking error signal T is supplied to the positive peak detection circuit 25 and the negative peak detection circuit 26 via the resistance ratio 8, respectively.

Here, the positive polarity peak detection circuit 25 detects the positive voltage peak level of the tracking error signal T, generates a positive voltage peak level signal V+T as shown in FIG. 6(C), and outputs it to the buffer amplifier IC2. It is something to do. It's Kade.
The negative polarity peak detection circuit 26 detects the negative voltage peak level of the tracking error signal 'f, generates a negative voltage peak level signal VT as shown in FIG. 6(d), and outputs it to the buffer amplifier IC3. It is something. The positive voltage and negative voltage peak level signals V+T and V-T outputted from the buffer amplifiers IC2 and Ca respectively have a resistance ratio of 6. It is supplied to the front s6 mixing and adding circuit 27 via the box 7. At this time, the differential amplifier I of the mixing adder circuit 27
C1 and negative feedback resistor R8 receive the positive voltage and negative voltage peak level signals V+T.

Based on the voltage V-T, a voltage signal V'cf is generated with a sharp line between the two voltage levels as shown in FIG. Add it.

Here, a signal obtained by inverting the polarity of the voltage signal v'c is a correction signal ΔT for correcting the offset voltage Vc of the tracking error signal T.

Then, the mixing and adding circuit 27 adds the tracking error signal T and the correction signal Δ']' to the offset l-i pressure Vc.
As shown in Figure (f) (・Racking error signal T+△
T is output. At this time, the tracking error signal ′
Since the offset voltage component Vc has been corrected for r, the positive voltage control area and the negative voltage control area are equal.

When the track jump operation is completed and the generation of the switching signal is stopped at time t, I1 in FIG. 6, the switch S is turned off and the tracking servo circuit 2o detects the tracking error. Tracking servo is applied to the signal T0 based on T.

Therefore, when the tracking servo is turned on, the positive voltage control area and the negative voltage control area of the tracking error signal T+△T are equal, so the tracking servo can be applied to the target bit string without causing the conventional problem. You will be able to apply it accurately and reliably. As a result, the tracking error signal T output from the tracking error signal generation circuit 19 conventionally takes time to converge after the tracking servo is turned on, as shown by the dotted line in FIG. 6(b). Things will immediately come to an end as shown by the solid line.

By the way, when this tracking servo is applied,
If the correction of offset error [i, positive component Vc of the above tracking error signal 'P' is done too quickly, the positive voltage control region and the negative voltage open side 1 There is a risk that the balance with the area will be lost and the spot may jump into the intended pit row as described above. Therefore, the voltage held in the capacitors CI and C2 of the positive and negative peak detection circuits 25 and 26 is discharged from the capacitors CI and C2.

The offset voltage Vci of the tracking error signal T is corrected until the tracking servo is completely performed.

Please refer to the positive polarity and negative @! used in the above example. , a switching circuit including an inverter, a transistor, etc. may be used for the input switching switch f8 of the peak detection circuit lIψ'r25.26.

Furthermore, the present invention is not limited to the above-mentioned embodiments, but is also effective in other types of disk record playback devices such as a tortoise type and a magnetic type. It is possible to give.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to eliminate the offset voltage of the tracking error signal at the time of track jump such as a fast search with a simple configuration, so that the offset voltage of the tracking error signal can be eliminated immediately even at the end of the track jump. It becomes possible to perform stable and reliable tracking servo.Therefore, this is an extremely good disc record playback device that expands the standards for pickups and can accurately search and read any data recorded on the disc in a short time. can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the tracking servo means and track jump means of a conventional disk record playback device, FIG. 2 is a block diagram illustrating a photodetector of the disk record playback device, and FIG. FIG. 4 is a characteristic diagram showing the tracking error signal by the tracking servo means, FIG. 4 is a characteristic diagram illustrating the change in the tracking error signal when the track jumps, and FIG. 5 is a characteristic diagram showing the tracking error signal of the tracking servo means. FIG. 6 is a block diagram showing an embodiment of the record reproducing apparatus, and is a characteristic diagram for explaining changes in the output waveforms and tracking error signals of the positive polarity and negative polarity peak detection circuits in the above embodiment. 1)...disc, 12...pickup, 13...
...Objective lens, 14...Tracking direction, 15.
...Moving coil, 16...Semiconductor laser, 17
...Beam splitter, 18...Photodetector, 19...Tracking error signal generation circuit 20...
・Tracking servo circuit, 2... System controller, 22... Track jump signal generation circuit, 2
3...Counter circuit, 24...Level compensation circuit, 2
5... Positive polarity peak detection circuit, 26... Negative polarity peak detection circuit, 27... Mixing addition circuit, 'P... Tracking error signal, Δ'F... Tracking error sleeve positive signal, L ...Switching signal, K...Truck jumping signal.

Claims (1)

[Claims] A pickup reads out the digitized data by tracing the pit strings on a disc on which digitized data obtained by encoding an information signal is recorded as a pit string. tracking servo means for generating a tracking error signal corresponding to the forward and reverse direction deviation of the pickup with respect to the pit row based on the tracking error signal and correcting the forward and reverse direction deviation of the pickup with respect to the pit row based on the tracking error signal; In a disc record playback device comprising a track jumping means for moving the pickup in a radial direction of the disc in response to a track jumping command, the tracking error signal is responsive to generation of the track jumping command. a peak detection circuit that generates a positive voltage peak level signal and a negative voltage peak level signal of the tracking error signal; a level signal generating means for generating a signal that is equal to the level; and an inverting and adding means for inverting the polarity of the signal obtained by the level signal generating means and adding it to the tracking error signal; A disc record reproducing apparatus characterized in that the DC offset of the tracking error signal is corrected by the DC offset of the tracking error signal.