JPH06195735A - Optical pickup device, and optical disc recording/ reproducing apparatus - Google Patents

Abstract

PURPOSE:To obtain an optical pickup device and an optical disc recording/ reproducing apparatus which can reduce noises of wobble signals and read the wobble data positively. CONSTITUTION:The pit data is read out in the form of a current from a wobble string recorded to an optical disc by a four-divide detector 1. The current is converted to a voltage by an I-V converting variable resistance 23, and the right and left outputs centered in the advancing direction of a track on the detector 1 are adjusted so that the AC components become the same. Accordingly, the leak of high frequency signals into tracking error signals is restricted, and noises of wobble signals are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and an optical disc recording / reproducing device for recording information on an optical disc or optically reading information from the optical disc.

[0002]

2. Description of the Related Art FIG. 6 shows a part of the structure of a conventional optical pickup device with a preamplifier. Is an IV conversion fixed resistor, which converts the current from the four-divided detector 1 into a voltage. Reference numeral 3 is a TE signal generation amplifier for generating a tracking error (TE) signal from the output of the IV conversion fixed resistor 2, and 4 is a high frequency (H).
F) an HF signal generation amplifier for generating a signal, 5 an FE signal generation amplifier for similarly generating a focus error (FE) signal, and 6 a balance correction of the DC of the TE signal generated in the TE signal generation amplifier 3. This is a TE signal balance correction circuit for performing the above, and the preamplifier unit 7 is configured by the portions indicated by reference numerals 2 to 6. 8 is a TE signal output terminal,
Reference numeral 9 is an HE signal output terminal, and 10 is an FE signal output terminal.

In the above structure, the light flux from the light source is projected onto the disk, the amount of light reflected from the disk is detected as a current by the four-division detector 1, and converted into a voltage by the IV conversion fixed resistor 2. Then, the TE, HF, and FE signals are generated from this voltage by the generation amplifiers 3 to 5, and the TE signal is balance-corrected for DC components by the balance correction circuit 6. Each signal is output from the output terminals 8-10.

FIG. 7 is a circuit rewrite of the configuration of FIG. 6. The IV conversion fixed resistor 2 is composed of an operational amplifier 11 and a resistor R ₁ corresponding to each output of the four-divided detector 1. ing. The TE signal generating amplifier 3 is composed of an operational amplifier 12 and resistors R ₂ , R ₅ and R ₆ , and the HF signal generating amplifier 4 is composed of an operational amplifier 12 and resistors R ₃ , R ₇ and R ₈ . The FE signal generating amplifier 5 includes an operational amplifier 12 and a resistor R.
_4, is composed of R _9, R _10, TE signal balance correction circuit 6 is composed of a variable resistor VR _1.

FIG. 8 shows the structure of a track servo system and a wobble system of a conventional optical disk recording / reproducing apparatus. The tracking motion and the motion of the light spot are compared, and the 4-division detector 1 detects the difference from the disc deviation. The amount of light is detected, converted into a voltage by the IV conversion fixed resistor 2, and a TE signal is generated by the TE signal generation amplifier 3. The TE signal balance correction circuit 6 performs offset correction of the TE signal.
The TE signal is amplified by the circuit system gain amplifier 16 and phase-compensated by the phase compensation circuit 17. The band pass filter 18 extracts a WE (wobble error) signal of a specific frequency from the TE signal, and the wobble C / N circuit 19 outputs W signal.
Determine C / N of E signal. The actuator 20 moves the lens of the optical system according to the input, and the linear motor 22 moves the entire pickup device according to the input signal input via the coupling compensation circuit 21 to sum the lens movement and the pickup movement. It becomes the movement of the light spot. The detailed circuit of the main part of the configuration of FIG. 8 is the same as that of FIG.

Next, a conventional CD-R recording / reproducing apparatus, its disc, and a CD-R optical pickup apparatus will be described. The CD-R recording / reproducing apparatus is capable of reproducing a CD disc, which is widely used at present, as well as being capable of writing information to the CD-R disc only once, and for writing the information to the CD-R. The disc can be played back by a CD player which is widely used at present. Thus, a conventional disc is called a CD disc, and a disc that can be written only once is called a CD-R disc.

Next, the difference between the CD disc and the CD-R disc will be described. First, on a CD disc, an EFM (Eight-Forteen Modulation) signal consisting of 3T to 11T (T is a period) has already been recorded, and absolute time information is included therein, and rotation control of the disc is also performed. It is performed by the EFM signal.
Also, when following the track direction of the optical pickup,
All you have to do is follow the pits provided from the beginning.

On the other hand, in the case of a CD-R disc, 3
The EFM signal consisting of T-11T has not been recorded in advance. Therefore, the EFM signal cannot be used for reading the absolute time information, controlling the rotation of the disk, and following the track direction of the optical pickup. For this reason,
The CD-R disc is preliminarily provided with spiral wobble rows, and absolute time information and disk rotation control information are recorded in the wobble rows. The wobble row is also used when spirally forming pits on a CD-R disc.

By the way, the wobble error signal (WE signal) obtained from this wobble sequence cannot reliably read the information contents unless the signal level is sufficiently higher than the noise level, and the absolute time information is surely obtained. It becomes impossible to read, and additional writing (joining) becomes impossible.

The reason why the signal level becomes smaller than the noise level, that is, the noise component becomes large and the C / N is deteriorated is due to the imbalance of the outputs (AC components of the A to D outputs) of the 4-division detector 1. It is a well-known fact that the HF signal leaks into the TE signal. The WE signal is also included in the TE signal.

In the case of the conventional optical pickup device or optical disc recording / reproducing device, each output from the four-divided detector 1 is output by a current, and only the DC offset of the TE signal is adjusted, and the AC component is adjusted. Was not done at all.

[0012]

The conventional optical pickup device or optical disk recording / reproducing device is constructed as described above, and the AC component of each signal output from the four-division detector 1 is not adjusted. It is necessary to perform this AC component adjustment on the recording / reproducing device side or the optical pickup side, or to fix the disc (manufacturer or model), and in some cases, the information of the WE signal from the disc cannot be read reliably. There were challenges.

The present invention has been made to solve the above problems, and can reduce the noise component of the WE signal and can reliably read the information from the WE signal. The purpose is to obtain a recording / reproducing apparatus.

[0014]

SUMMARY OF THE INVENTION Claims 1 and 4 of the present invention
The optical pickup device and the optical disk recording / reproducing device according to the present invention convert the current output from the detector into a voltage and make the AC components of the left and right detector outputs centered on the track traveling direction on the detector equal. I-V to adjust to
The conversion means is provided.

The optical pickup device and the optical disk recording / reproducing device according to the second and fifth aspects are, in addition to the first and fourth aspects,
There is provided means for injecting a DC offset voltage into the tracking error signal generated from the output of the IV converting means and performing balance correction for the DC.

In the optical pickup device and the optical disc recording / reproducing device according to the third and sixth aspects, a means for correcting the DC component of the tracking error signal and outputting it for tracking control, and a means for correcting the AC component of the tracking error signal and wobble. A means for outputting for reading information is provided.

[0017]

According to the present invention, the AC components of the left and right detector outputs centering around the track traveling direction on the detector are adjusted to be the same, and the high frequency signal leaks into the tracking error signal. The wobble error signal noise is reduced, and accurate wobble information can be obtained.

According to the second and fifth aspects, in addition to the first and fourth aspects, the DC offset voltage is injected into the tracking error signal to correct the balance of the DC component, and the tracking control is stably performed.

In the third and sixth aspects, the DC component of the tracking error signal is corrected and output for tracking control, and the tracking control is stably performed. or,
The AC component of the tracking error signal is corrected and output for reading the wobble information, the noise of the wobble error signal is suppressed, and the wobble information is surely read.

[0020]

EXAMPLE 1 Example 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an optical pickup device with a preamplifier according to the first embodiment. Reference numeral 23 is an AC component adjustment IV conversion variable resistor, and the preamplifier section 7 is constituted by the portions indicated by reference numerals 3 to 6 and 23. 2 shows the configuration of FIG. 1 in detail, and the IV conversion variable resistor 23 is the operational amplifier 2
4 and the resistor R ₁₁ and the variable resistor VR ₂ (however, the variable resistor VR ₂ is not provided for the one corresponding to the A output), and the TE signal balance correction circuit 6 includes the resistor R
It is composed of ₁₂ and a variable resistor VR ₁ .

In the first embodiment, a variable resistor VR ₂ is provided in the IV conversion variable resistor 23, and the AC (AC) output on the left and right with respect to the traveling direction of the pits of the optical disc in the four-division detector 1 is the same before the TE signal is generated. Is adjusted so that That is, FIG. 3 shows the relationship between the traveling direction of the track on the four-division detector 1 and the TE signal.
If the signal is generated by (= A + D)-(B + C),
It is necessary to adjust the AC component of (A + D) and the AC component of (B + C) to be equal.

However, in reality, the shape of the light spot applied to the optical disk is not a perfect circle, the difference in the intensity distribution of the light beam, the variation in the sensitivity of the four-division detector 1, the light spot and the four-division detector 1. (A
An imbalance occurs between the + D) AC component and the (B + C) AC component. Therefore, in the first embodiment, the preamplifier unit 7 is mounted, the variable resistor VR ₂ is provided at each output stage of B to D of the four-divided detector 1, and the AC component of the B to D outputs is the A output with reference to the A output. So that the output is the same as the AC component of
The V conversion variable resistor 23 is adjusted. As a result, A in the left and right outputs of the 4-division detector 1 with respect to the track traveling direction
The C component has the same output.

However, if the AC components of the A to D outputs of the four-division detector 1 are adjusted to the same level before the TE signal is generated, the DC component of the TE signal will also change.
Therefore, a DC offset voltage is injected into the TE signal from the TE signal balance correction circuit 6 to perform the DC component balance correction of the TE signal. For the balance correction of this DC component, the method of injecting the DC offset voltage in this way and (A +
There is a balancer method for adjusting the circuit gains of D) and (B + C). However, if the latter balancer method is adopted after adjustment of AC as in the present embodiment, (A + D) and (B +).
An imbalance occurs in the output voltage of C), and there is no point in adjusting the AC component.

Embodiment 2 FIG. 4 shows the structure of an optical pickup device with a preamplifier according to Embodiment 2, 25 is a high-pass filter, and 26 is a T.
A balance correction circuit for correcting the AC component of the E signal, 27 is a TE signal generation amplifier, and 28 is a TE signal output terminal.

FIG. 5 shows a detailed circuit configuration of FIG. 4, in which the high-pass filter 25 includes a capacitor C ₁ and resistors R ₁₃ and R _14.
It consists of The TE signal generating amplifier 27 is composed of operational amplifiers 29, 30 and resistors R _{15 to} R ₁₈ , and the balance correction circuit 26 has a resistor R ₁₉ and a variable resistor VR.
_It consists of _three .

Next, the operation of the second embodiment will be described.
The amount of light returned from the disk is detected as a current by the four-division detector 1, this is converted into a voltage by the IV conversion fixed resistor 2, and a TE signal, an HF signal, and an FE signal are generated from this voltage as in the conventional case. Then, the TE signal has its DC component corrected by the balance correction circuit 6, and is output from the output terminal 8 for track servo. Further, the output voltage of the IV conversion fixed resistor 2 is input to the high-pass filter 25, the DC component is cut off, the TE signal is generated, and the balance correction circuit 26 causes the pit on the 4-division detector 1 to be generated. The left (A + D) and right (B + C) AC outputs with respect to the traveling direction of are adjusted to be the same output. This TE signal is output from the output terminal 28 for reading the WE signal.

Third Embodiment FIG. 9 shows the structure of an optical disk recording / reproducing apparatus according to a third embodiment. The difference from the conventional apparatus of FIG. 8 is the IV conversion fixed resistor 2
Is the I-V conversion variable resistor 23, and the main circuit thereof is also the same as in FIG. Therefore, this is the same as the first embodiment, and the operation and the effect are also the same.

Embodiment 4 FIG. 10 shows the structure of an optical disk recording / reproducing apparatus according to Embodiment 4, and the difference from the conventional apparatus of FIG. 8 is the high-pass filter 2.
5, a TE signal generation amplifier 27 and a TE signal balance correction circuit 26 are added, and the main circuit is shown in FIG.
Is the same as. Therefore, this is similar to Example 2,
The action and effect are similar.

[0029]

As described above, according to claims 1 and 4 of the present invention, since the AC components of the left and right detector outputs are corrected so as to be the same before the generation of the tracking error signal, the wobble information is surely obtained. It can be read, and the absolute time information and the disk rotation control information can be read reliably.

According to the present invention, the AC components of the left and right detector outputs are corrected and the left and right detector outputs D are corrected.
Since the C component (deviation in the balance of the tracking error signal) is corrected by injecting the DC offset voltage, accurate wobble information can be obtained as described above and stable tracking control can be performed.

According to the third and sixth aspects, the tracking error signal in which the DC component is corrected is used for tracking control, and the tracking error signal in which the AC component is corrected is used for wobble information reading. In addition to being readable, stable tracking control can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical pickup device according to a first embodiment.

FIG. 2 is a circuit diagram of the configuration of FIG.

FIG. 3 is a relationship diagram between a traveling direction of a track on a detector and a TE signal.

FIG. 4 is a configuration diagram of an optical pickup device according to a second embodiment.

5 is a circuit diagram of the configuration of FIG.

FIG. 6 is a configuration diagram of a conventional optical pickup device.

FIG. 7 is a circuit diagram of the configuration of FIG.

FIG. 8 is a block diagram of a conventional optical disc recording / reproducing apparatus.

FIG. 9 is a configuration diagram of an optical disc recording / reproducing apparatus according to a third embodiment.

FIG. 10 is a configuration diagram of an optical disc recording / reproducing apparatus according to a fourth embodiment.

[Explanation of symbols]

 1 4-division detector 2 IV conversion fixed resistance 3,27 TE signal generation amplifier 6 TE signal balance correction circuit (DC portion) 23 IV conversion variable resistance 26 TE signal balance correction circuit (AC portion)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuma Sato 800 Iwamatsu, Oshima-cho, Nitta-gun, Gunma Sanryo Electric Co., Ltd. Gunma Factory

Claims (6)

[Claims] 1. A detector for reading pit information from a wobble sequence recorded on an optical disc and outputting the pit information as a current, and a current on the detector while converting the current output from the detector into a voltage. The optical pickup device is provided with an IV conversion means for adjusting the AC components of the left and right detector outputs centering around the traveling direction of the. 2. A means for generating a tracking error signal from the output of the IV conversion means, and a means for injecting a DC offset voltage into the tracking error signal to correct the balance of the DC. The optical pickup device according to claim 1. 3. A detector for reading pit information from a wobble string recorded on an optical disk and outputting the pit information as a current, an IV conversion means for converting the current output from the detector into a voltage, and I A means for generating a tracking error signal from the output of the -V conversion means, a means for correcting the DC component of the tracking error signal and outputting it for tracking control, and a means for correcting the AC component of the tracking error signal for reading wobble information. An optical pickup device comprising means for outputting. 4. A detector for reading pit information from a wobble sequence recorded on an optical disc and outputting the pit information as a current, and a current on the detector while converting the current output from the detector into a voltage. Of the left and right detectors centering around the traveling direction of the I-V conversion means, a means for generating a tracking error signal from the output of the IV conversion means, and the tracking error An optical disk recording / reproducing apparatus comprising means for performing tracking control according to a signal. 5. The optical disk recording / reproducing apparatus according to claim 4, further comprising means for injecting a DC offset voltage into the tracking error signal to correct the balance of the DC. 6. A detector for reading pit information from a wobble train recorded on an optical disk and outputting the pit information as a current, an IV converting means for converting the current output from the detector into a voltage, and I. A means for generating a tracking error signal from the output of the -V conversion means, a means for correcting the DC component of the tracking error signal and outputting it for tracking control, and a means for correcting the AC component of the tracking error signal for reading wobble information. An optical disk recording / reproducing apparatus, characterized by comprising a means for outputting.