CN1296915C

CN1296915C - Device and method for gain correction of differential push-pull tracking error signal

Info

Publication number: CN1296915C
Application number: CNB02142229XA
Authority: CN
Inventors: 吴文义; 徐敬全; 许汉文
Original assignee: MediaTek Inc
Current assignee: MediaTek Inc
Priority date: 2002-08-26
Filing date: 2002-08-26
Publication date: 2007-01-24
Anticipated expiration: 2022-08-26
Also published as: CN1479283A

Abstract

A gain correction device and method for differential push-pull tracking error signal in optical disc access system are disclosed. The gain correction deals with the resultant gain of the auxiliary beam relative to the main beam in the DPP tracking error signal component. The correction principle is to control the objective lens of the optical pickup head to generate a deviation or to control the relative tilt angle between the objective lens and the optical disc, so that the synthesized DPP tracking error signal generates a corresponding signal change amount due to the optical path variation. The synthesized gain is corrected to make the signal variation amount be minimum value, and the synthesized gain obtained by the correction is the optimum value. The method and the device can accurately calculate the optimal synthetic gain of the auxiliary beam without assuming that the two auxiliary beams have the same intensity and are symmetrical to the main beam in position and knowing the ratio of the space between the two auxiliary beams and the space between the tracks.

Description

Device and method for gain correction of differential push-pull tracking error signal

技术领域technical field

本发明关于光盘存取系统中的差动推挽式(Differential Push-Pull，以下简称DPP)寻轨误差信号的增益校正装置及方法，特别是针对DPP信号分量中的辅助光束相对于主要光束的合成增益(SPPG)的校正装置及方法。The present invention relates to a differential push-pull (Differential Push-Pull, hereinafter referred to as DPP) tracking error signal gain correction device and method in an optical disc access system, especially for the difference between the auxiliary beam in the DPP signal component and the main beam A calibration device and method for synthetic gain (SPPG).

背景技术Background technique

图1所示为差动推挽式架构的寻轨误差分析的光盘片激光光斑结构。如图1所示，对一般差动推挽式架构的寻轨误差(Tracking Error，TE)分析，共有三个激光束打在光盘片上，分别为主要光束(Main beam)12、第一辅助光束(First Sub beam)13、以及第二辅助光束(Second Sub beam)14。因此，DPP的寻轨误差信号TE可被表示成主要光束12的推挽信号MPP与辅助光束13、14的推挽信号SPP的差动合成，如式(1)：Figure 1 shows the laser spot structure of the optical disc for tracking error analysis of the differential push-pull architecture. As shown in Figure 1, for the tracking error (Tracking Error, TE) analysis of the general differential push-pull architecture, there are three laser beams hitting the optical disc, namely the main beam (Main beam) 12, the first auxiliary beam (First Sub beam) 13, and the second auxiliary beam (Second Sub beam) 14. Therefore, the tracking error signal TE of the DPP can be expressed as a differential synthesis of the push-pull signal MPP of the main beam 12 and the push-pull signal SPP of the auxiliary beams 13 and 14, as shown in formula (1):

TE＝MPP-α·SPP (1)TE＝MPP-α SPP (1)

其中，α为辅助光束13、14的推挽信号SPP相对于主要光束12的推挽信号MPP的合成增益SPPG。Wherein, α is the synthesis gain SPPG of the push-pull signal SPP of the auxiliary beam 13 , 14 relative to the push-pull signal MPP of the main beam 12 .

根据图1光盘片上的激光光斑排列组态，主要光束12的推挽信号MPP与辅助光束13、14的推挽信号SPP可表示成式(2)与式(3)：According to the arrangement of laser spots on the optical disc in Fig. 1, the push-pull signal MPP of the main beam 12 and the push-pull signal SPP of the auxiliary beams 13 and 14 can be expressed as formula (2) and formula (3):

$MPP MPP = = {A A}_{m m} \cdot \cdot sin sin ((\frac{22 πx πx}{P P})) + + {A A}_{m m} \cdot &Center Dot; K K ((tilt tilt)) + + {C C}_{m m} - - - - - - ((22))$

$SPP SPP = = SPA SPA + + SPP SPP 22$

$= = [[{A A}_{S S 11} \cdot &Center Dot; sin sin ((\frac{22 π π \cdot &Center Dot; ((x x - - {Q Q}_{11}))}{P P})) + + {A A}_{S S 11} \cdot &Center Dot; K K ((tilt tilt)) + + {C C}_{S S 11}]] + + [[{A A}_{S S 22} \cdot \cdot sin sin ((\frac{22 π π \cdot \cdot ((x x + + {Q Q}_{22}))}{P P})) + + {A A}_{S S 22} \cdot \cdot K K ((tilt tilt)) + + {C C}_{S S 22}]]$

$= = (({A A}_{S S 11} \cdot \cdot cos cos ((\frac{{22 πQ πQ}_{11}}{P P})) + + {A A}_{S S 22} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{22}}{P P})))) \cdot \cdot sin sin ((\frac{22 πx πx}{P P})) + + (({A A}_{S S 22} \cdot \cdot sin sin ((\frac{{22 πQ πQ}_{22}}{P P})) - - {A A}_{S S 11} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{11}}{P P})))) \cdot \cdot cos cos ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{S S 11} + + {A A}_{S S 22})) \cdot \cdot K K ((tilt tilt)) + + (({C C}_{S S 11} + + {C C}_{S S 22}))$

(3)(3)

其中，x为主要激光束12的光斑中心15到轨道(Groove)中心10的偏移量，且为时间t的函数。与x有关的项目即所谓的AC分量(较Tilt变异高频)，且受到光盘片偏心跨轨量(RUNOUT)影响。Q1、Q2为第一、第二辅助光束13、14的光斑中心16、17到主要激光束12的光斑中心15的距离。P为光盘片上的数据轨道间距，即轨道中心10、10’之间的距离。Am、As1、As2为寻轨误差信号TE的AC振幅，也就是偏心跨轨量的振幅。而Cm、Cs1、Cs2为前级放大器(RFIC)及光学信号放大器(PDIC)的OP放大器的电路信号偏移量(OFFSET)。K(tilt)为正比于光学读取头倾斜量的变量，该光学读取头倾斜是由透镜偏移(lens-shift)或光学机构的误差所造成。Wherein, x is the offset from the spot center 15 of the main laser beam 12 to the groove center 10 and is a function of time t. The item related to x is the so-called AC component (higher frequency than Tilt variation) and is affected by disc eccentricity cross-track amount (RUNOUT). Q1 and Q2 are the distances from the spot centers 16 and 17 of the first and second auxiliary beams 13 and 14 to the spot center 15 of the main laser beam 12 . P is the data track pitch on the optical disc, that is, the distance between track centers 10 and 10'. Am, As1, As2 are the AC amplitude of the tracking error signal TE, that is, the amplitude of the eccentric cross-track amount. And Cm, Cs1, Cs2 are the circuit signal offset (OFFSET) of the OP amplifier of the preamplifier (RFIC) and the optical signal amplifier (PDIC). K(tilt) is a variable proportional to the amount of optical pickup tilt caused by lens-shift or optical mechanism errors.

因此，将式(2)与(3)带入式(1)，则寻轨误差信号TE可表示成式(4)：Therefore, putting equations (2) and (3) into equation (1), the tracking error signal TE can be expressed as equation (4):

$TE TE = = MPP MPP - - α α \cdot &Center Dot; SPP SPP$

$= = (({A A}_{m m} - - α α \cdot &Center Dot; (({A A}_{S S 11} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{11}}{P P})) + + {A A}_{S S 22} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{22}}{P P})))))) \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P}))$

$- - α α \cdot &Center Dot; (({A A}_{S S 22} \cdot \cdot sin sin ((\frac{{22 πQ πQ}_{22}}{P P})) - - {A A}_{S S 11} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{11}}{P P})))) \cdot &Center Dot; cos cos ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{m m} - - α α \cdot &Center Dot; (({A A}_{S S 11} + + {A A}_{S S 22})))) \cdot \cdot K K ((tilt tilt)) + + (({C C}_{m m} - - α α \cdot &Center Dot; (({C C}_{S S 11} + + {C C}_{S S 22}))))$

(4)(4)

为了使寻轨误差信号TE不受K(tilt)变量的影响，一般是设定适当的合成增益SPPG值，使得式(4)中的第三项为0。现有的方式是先假设In order to prevent the tracking error signal TE from being affected by the K(tilt) variable, generally an appropriate synthetic gain SPPG value is set so that the third item in the formula (4) is 0. The existing method is to assume

1.A_s1＝A_s2＝A_s 1. A _s1 =A _s2 =A _s

2.Q₁＝Q₂＝Q2. Q ₁ =Q ₂ =Q

3.Q/P为已知3. Q/P is known

因此，若将上述假设值带入式(4)，则式(4)可简化成式(5)：Therefore, if the above assumptions are brought into formula (4), then formula (4) can be simplified into formula (5):

$TE TE = = MPP MPP - - α α \cdot \cdot SPP SPP$

$= = (({A A}_{m m} - - α α \cdot &Center Dot; 22 \cdot &Center Dot; {A A}_{S S} \cdot \cdot cos cos ((\frac{22 πQ πQ}{P P})))) \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P})) + + (({A A}_{m m} - - α α \cdot \cdot 22 \cdot \cdot {A A}_{S S})) \cdot \cdot K K ((tilt tilt))$

$+ + (({C C}_{m m} - - α α \cdot \cdot (({C C}_{S S 11} + + {C C}_{S S 22}))))$

(5)(5)

所以，主要光束12与辅助光束13、14的推挽信号MPP及SPP的AC项可用来校正α值。其校正方法如下：Therefore, the AC terms of the push-pull signals MPP and SPP of the main beam 12 and the auxiliary beams 13, 14 can be used to correct the α value. Its correction method is as follows:

步骤1：调整电路的OFFSET值C_m、C_s1与C_s2为0；Step 1: Adjust the OFFSET values C _m , C _s 1 and C _s2 of the circuit to 0;

步骤2：测量MPP的AC项的振幅，MA＝A_m；Step 2: measure the amplitude of the AC term of the MPP, MA=A _m ;

步骤3：测量SPP的AC项的振幅， $SA = 2 \cdot A_{s} \cos (\frac{2 πQ}{P})$ Step 3: Measure the amplitude of the AC term of the SPP, $SA = 2 \cdot A_{the s} \cos (\frac{2 πQ}{P})$

步骤4：定义SPP的合成增益 $α = \frac{MA \cdot \cos (\frac{2 πQ}{P})}{SA} = \frac{A_{m}}{2 \cdot A_{s}}$ Step 4: Define the synthetic gain of the SPP $α = \frac{MA &Center Dot; \cos (\frac{2 πQ}{P})}{SA} = \frac{A_{m}}{2 &Center Dot; A_{the s}}$

步骤5：将步骤4的α值带入式(5)，即可获得只有AC项的函数，如式(6)所示：Step 5: Bring the α value of step 4 into formula (5), and then the function with only AC term can be obtained, as shown in formula (6):

$TE TE = = MPP MPP - - α α \cdot \cdot SPP SPP$

$= = (({A A}_{m m} - - α α \cdot \cdot 22 \cdot \cdot {A A}_{S S} \cdot \cdot cos cos ((\frac{22 πQ πQ}{P P})))) \cdot \cdot sin sin ((\frac{22 πx πx}{P P})) + + (({A A}_{m m} - - α α \cdot \cdot 22 \cdot &Center Dot; {A A}_{S S})) \cdot &Center Dot; K K ((tilt tilt))$

$+ + (({C C}_{m m} - - α α \cdot &Center Dot; (({C C}_{S S 11} + + {C C}_{S S 22}))))$

$= = {A A}_{m m} \cdot \cdot ((11 - - cos cos ((\frac{22 πQ πQ}{P P})))) \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P}))$

(6)(6)

但是，上述现有方法必须满足三个假设。然而，Q/P、A_s1、A_s2、Q₁、Q₂的值会因为不同的光学读取头以及光盘片而改变。因此，无法在SPP增益的校正期间获得该等信息。所以，无法以此现有技术获得正确的SPP的增益α。However, the above existing methods must satisfy three assumptions. However, the values of Q/P, A _s1 , A _s2 , Q ₁ , and Q ₂ will vary due to different optical pick-up heads and optical discs. Therefore, such information cannot be obtained during the calibration of the SPP gain. Therefore, the correct gain α of the SPP cannot be obtained with this prior art.

发明内容Contents of the invention

鉴于上述问题，本发明的目的是提供一种光盘存取系统中的差动推挽式寻轨信号的合成增益SPPG的校正方法与装置，用于在不需假设二辅助光束强度相同且位置对称于主要光束，而且不需知道二辅助光束间距与轨道间距的比例的情形下，即可精确计算出最佳的SPPG值。In view of the above problems, the purpose of the present invention is to provide a method and device for correcting the composite gain SPPG of the differential push-pull tracking signal in the optical disc access system, which is used for without assuming that the intensity of the two auxiliary beams is the same and the positions are symmetrical The optimal SPPG value can be accurately calculated without knowing the ratio of the distance between the two auxiliary beams to the track pitch in the case of the main beam.

为实现上述目的，本发明提供了一种光盘存取系统中的差动推挽式寻轨误差的增益校正方法，用来校正辅助光束的放大器增益相对于主要光束的放大器增益的值，该增益校正方法包含下列步骤：开启激光光源并进行光束聚焦；启动主轴电机并设定一初值增益，即设定辅助光束推挽放大器的初值增益；控制物镜与盘片处于第一相对变化状态；测量与物镜偏移有关的主要光束的推挽信号的特征值，以作为第一主要光束特征值；测量与物镜偏移有关的辅助光束的推挽信号的特征值，以作为第一辅助光束特征值；控制物镜与盘片处于第二相对变化状态；测量与物镜偏移有关的主要光束的推挽信号的特征值，以作为第二主要光束特征值；测量与物镜偏移有关的辅助光束的推挽信号的特征值，以作为第二辅助光束特征值；以及，计算增益，即根据第一主要光束特征值、第一辅助光束特征值、第二主要光束特征值、以及第二辅助光束特征值计算辅助光束的增益。To achieve the above object, the present invention provides a differential push-pull tracking error gain correction method in an optical disc access system, which is used to correct the value of the amplifier gain of the auxiliary beam relative to the amplifier gain of the main beam, the gain The correction method includes the following steps: turn on the laser light source and focus the beam; start the spindle motor and set an initial gain, that is, set the initial gain of the auxiliary beam push-pull amplifier; control the objective lens and the disc to be in the first relative change state; Measure the eigenvalue of the push-pull signal of the main beam related to the objective lens offset as the first main beam eigenvalue; measure the eigenvalue of the push-pull signal of the auxiliary beam related to the objective lens offset as the first auxiliary beam characteristic value; control the objective lens and the disc to be in the second relative change state; measure the eigenvalue of the push-pull signal of the main beam related to the objective lens offset as the second main beam eigenvalue; measure the auxiliary beam related to the objective lens offset the eigenvalue of the push-pull signal as the second auxiliary beam eigenvalue; The value calculates the gain of the auxiliary beam.

为实现上述目的，本发明提供了一种光盘存取系统中的差动推挽式寻轨误差的增益校正装置，用来校正辅助光束的放大器增益相对于主要光束的放大器增益的值，该增益校正装置包含：一光学信号放大器，接收主要光束与辅助光束经由盘片反射的信号，并放大后输出成主要光束射频信号与辅助光束射频信号；一射频接收器，经由前级将光学信号放大器的主要光束射频信号与辅助光束射频信号差动放大，再将该等放大的信号经由主要光束信号放大器与辅助光束信号放大器差动放大后，产生主要光束推挽信号与辅助光束推挽信号，并输出该等主要光束推挽信号与辅助光束推挽信号的差值作为差动推挽式寻轨误差信号；一模拟数字转换器，接收射频接收器的主要光束推挽信号与辅助光束推挽信号，并产生数字主要光束推挽信号与数字辅助光束推挽信号；以及，一数字信号处理器，接收数字主要光束推挽信号与数字辅助光束推挽信号，并利用一特征抽取器来抽取该数字主要光束推挽信号与数字辅助光束推挽信号的特征值，并通过一增益计算模块根据该等推挽信号的特征值计算射频接收器的辅助光束信号放大器相对于主要光束信号放大器的增益。To achieve the above object, the present invention provides a differential push-pull tracking error gain correction device in an optical disc access system, which is used to correct the value of the amplifier gain of the auxiliary beam relative to the amplifier gain of the main beam, the gain The correction device includes: an optical signal amplifier, which receives the signals reflected by the main beam and the auxiliary beam through the disc, and amplifies and outputs the radio frequency signal of the main beam and the radio frequency signal of the auxiliary beam; The main beam radio frequency signal and the auxiliary beam radio frequency signal are differentially amplified, and then the amplified signals are differentially amplified by the main beam signal amplifier and the auxiliary beam signal amplifier to generate the main beam push-pull signal and the auxiliary beam push-pull signal, and output The difference between the main beam push-pull signal and the auxiliary beam push-pull signal is used as a differential push-pull tracking error signal; an analog-to-digital converter receives the main beam push-pull signal and the auxiliary beam push-pull signal of the radio frequency receiver, and generate a digital main beam push-pull signal and a digital auxiliary beam push-pull signal; and, a digital signal processor receives the digital main beam push-pull signal and the digital auxiliary beam push-pull signal, and uses a feature extractor to extract the digital main beam The eigenvalues of the beam push-pull signal and the digital auxiliary beam push-pull signal, and a gain calculation module calculates the gain of the auxiliary beam signal amplifier of the radio frequency receiver relative to the main beam signal amplifier according to the eigenvalues of the push-pull signals.

因此，本发明的校正装置与方法可确保所合成的差动推挽式寻轨误差(DPP)信号在遭遇如寻轨过程中物镜的晃动(lens-shift)、物镜或光盘片因机构容差(tolerance)形成的倾斜角度(Tilt)等光学路径扰动变异时，信号电平不受干扰，使光盘片轨道(Groove)的中心位置维持在DPP信号的参考电平，确保锁轨伺服控制的激光光斑(Laser Spot)对准轨道的中心位置。同时，在跳轨-锁轨的反复过程中，DPP信号位准因不受干扰而呈现正相与负相振幅均衡(Balanced)的符合标准波形。而且，此校正装置所得的合成增益(SPPG)值不受光学读取头的内部机构容差所形成的激光光斑位置误差、或不同光盘片的轨距(Track Pitch)变异等因素的影响。故一致性与稳定性佳，易于推广于工业应用。Therefore, the correction device and method of the present invention can ensure that the synthesized differential push-pull tracking error (DPP) signal encounters such as lens-shift of the objective lens during the tracking process, or the objective lens or the optical disc due to mechanism tolerance When the optical path is disturbed and changed by the tilt angle (Tilt) formed by (tolerance), the signal level will not be disturbed, so that the center position of the disc track (Groove) can be maintained at the reference level of the DPP signal, and the laser track-lock servo control can be ensured. The laser spot is aligned with the center of the track. At the same time, in the repeated process of track jumping and track locking, the DPP signal level presents a standard waveform with balanced positive and negative amplitudes due to no interference. Moreover, the composite gain (SPPG) value obtained by the correction device is not affected by factors such as the laser spot position error formed by the internal mechanism tolerance of the optical pickup head, or the track pitch (Track Pitch) variation of different optical discs. Therefore, the consistency and stability are good, and it is easy to be popularized in industrial applications.

附图说明Description of drawings

参照附图对本发明的详细描述，本发明的上述目的、特征和优点将变得更加清楚，附图中：With reference to the detailed description of the present invention with reference to the accompanying drawings, the above-mentioned purpose, features and advantages of the present invention will become more clear, in the accompanying drawings:

图1所示为差动推挽式架构的寻轨误差分析的光盘片激光光斑结构；Figure 1 shows the optical disc laser spot structure for tracking error analysis of the differential push-pull architecture;

图2所示为差动推挽式寻轨误差信号的校正系统；Figure 2 shows the correction system of the differential push-pull tracking error signal;

图3所示为图2的校正系统中的数字信号处理器的方块图；Figure 3 is a block diagram of a digital signal processor in the correction system of Figure 2;

图4所示为差动推挽式寻轨误差信号的校正系统的另一实施例；Fig. 4 shows another embodiment of the correction system of the differential push-pull tracking error signal;

图5所示为本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法的数学证明的流程图；和Fig. 5 shows the flowchart of the mathematical proof of the gain correction method of the differential push-pull tracking error in the optical disc access system of the present invention; and

图6所示为本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法的实施例的流程图。FIG. 6 is a flow chart of an embodiment of a differential push-pull tracking error gain correction method in an optical disc access system of the present invention.

具体实施方式Detailed ways

以下参考图式详细说明本发明光盘存取系统中的差动推挽式寻轨的增益校正方法。以下说明均以对物镜作偏移运动的控制、且控制的方式为采步进响应(Step response)的实施例。The gain correction method of the differential push-pull tracking in the optical disc access system of the present invention will be described in detail below with reference to the figures. The following descriptions are all based on the implementation of the control of the offset movement of the objective lens, and the control method is an embodiment of adopting a step response (Step response).

图2为本发明所提出的差动推挽式寻轨误差信号的校正系统。该校正系统20包括前级放大器(RFIC)21、模拟/数字转换器(Analog/Digital Converter，A/D)22、数字信号处理器(DSP)23、物镜运动致动器24、以及光学装置25。FIG. 2 is a correction system for a differential push-pull tracking error signal proposed by the present invention. This correction system 20 comprises preamplifier (RFIC) 21, analog/digital converter (Analog/Digital Converter, A/D) 22, digital signal processor (DSP) 23, objective lens movement actuator 24 and optical device 25 .

前级放大器21用于接收从光学信号检测与放大器254所输出的光学读取头的信号(A，B，C，D，E，F，G，H)并将其放大、合成至锁轨伺服控制所需的信号，包括主要光束的推挽信号MPP’、辅助光束的推挽信号SPP’、以及差动推挽误差信号DPP。辅助光束的推挽信号SPP利用OP放大器214先将第一辅助光束与第二辅助光束的光学读取头信号E，F，G，H先合并后再差动放大，可节省前级放大器21的输入脚的数量。辅助光束的推挽信号SPP经由OP放大器212放大后产生辅助光束的推挽信号SPP’。而主要光束的推挽信号MPP是利用OP放大器213先将光学读取头信号A，B，C，D先合并后再差动放大，再经由OP放大器211放大后产生主要光束的推挽信号MPP’。The pre-amplifier 21 is used to receive the signals (A, B, C, D, E, F, G, H) of the optical pick-up head output from the optical signal detection and amplifier 254 and amplify and synthesize them to the track-lock servo The signals required for control include the push-pull signal MPP' of the main beam, the push-pull signal SPP' of the auxiliary beam, and the differential push-pull error signal DPP. The push-pull signal SPP of the auxiliary light beam utilizes the OP amplifier 214 to first combine the optical pickup head signals E, F, G, and H of the first auxiliary light beam and the second auxiliary light beam and then differentially amplify it, which can save the power of the preamplifier 21. Enter the number of feet. The push-pull signal SPP of the auxiliary beam is amplified by the OP amplifier 212 to generate the push-pull signal SPP' of the auxiliary beam. The push-pull signal MPP of the main light beam is to use the OP amplifier 213 to first combine the optical pickup head signals A, B, C, D and then differentially amplify them, and then amplify them through the OP amplifier 211 to generate the push-pull signal MPP of the main light beam '.

模拟-数字转换器22用以转换模拟的主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’信号至数字的形式，使其可被数字信号处理器23作进一步处理。数字信号处理器23从主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’抽取出所需的特征分量，并依主要光束12的推挽信号MPP’与辅助光束13、14的推挽信号SPP’中特征分量的多寡，调整前级放大器21中差动推挽式寻轨信号的合成增益SPPG增益(α)。此外，数字信号处理器23和控制物镜253以某一特定波形的运动方式改变其物镜偏移量(Lens-shift)或倾斜角(lens-tilt)。再者，数字信号处理器23也控制前级放大器21中主要光束12的推挽信号MPP’与辅助光束13、14的推挽信号SPP’的电子信号偏移量(MPP_offset与SPP_offset)，以配合校正程序中使用。The analog-to-digital converter 22 is used to convert the analog push-pull signal MPP' of the main beam and the push-pull signal SPP' of the auxiliary beam into a digital form, so that it can be further processed by the digital signal processor 23 . The digital signal processor 23 extracts the required characteristic components from the push-pull signal MPP' of the main beam and the push-pull signal SPP' of the auxiliary beam, and pushes the characteristic components according to the push-pull signal MPP' of the main beam 12 and the auxiliary beams 13 and 14. The amount of the characteristic component in the pull signal SPP′ adjusts the composite gain SPPG gain (α) of the differential push-pull tracking signal in the preamplifier 21 . In addition, the digital signal processor 23 and the control objective lens 253 change its objective lens offset (Lens-shift) or tilt angle (lens-tilt) in a movement manner of a specific waveform. Furthermore, the digital signal processor 23 also controls the electronic signal offset (MPP_offset and SPP_offset) of the push-pull signal MPP' of the main beam 12 and the push-pull signal SPP' of the auxiliary beams 13, 14 in the preamplifier 21 to match used in calibration procedures.

物镜运动致动器24接收数字信号处理器23的物镜运动控制信号以控制物镜253的运动。该物镜运动致动器24可为跨轨方向的致动器(trackingactuator)以产生物镜偏移运动(Lens-shift)、或为旋转物镜面的致动器(tiltactuator)以产生物镜倾斜运动(Lens-tilt)。The objective lens movement actuator 24 receives the objective lens movement control signal from the digital signal processor 23 to control the movement of the objective lens 253 . The objective lens motion actuator 24 can be an actuator (trackingactuator) in the direction of the track to produce the objective lens shifting motion (Lens-shift), or an actuator (tiltactuator) to rotate the objective lens surface to produce the objective lens tilting motion (Lens-shift). -tilt).

光学装置25包括激光产生及驱动电路(LD)251、分光透镜组(Splitter)252、物镜(Objective lens)253、及光学信号检测与放大器(PDIC)254。激光束由激光产生及驱动电路251产生，并经由分光透镜组252形成主要光束12、第一辅助光束13、以及第二辅助光束14后，透过物镜253打在光盘片26的数据轨道附近。经由光盘片26反射的光束，通过光学信号检测与放大器(PDIC)254产生光转电信号A、B、C、D、E、F、G、H。而光转电信号A、B、C、D为主要光束的信号、光转电信号F与G为第一辅助光束的信号、以及光转电信号E与H为第二辅助光束的信号。光转电信号A、B、C、D、E、F、G、H对应于的位置光学信号检测与放大器254的位置如图2所示。The optical device 25 includes a laser generating and driving circuit (LD) 251 , a splitter lens group (Splitter) 252 , an objective lens (Objective lens) 253 , and an optical signal detection and amplifier (PDIC) 254 . The laser beam is generated by the laser generating and driving circuit 251, and forms the main beam 12, the first auxiliary beam 13, and the second auxiliary beam 14 through the beam splitting lens group 252, and passes through the objective lens 253 to strike near the data track of the optical disc 26. The light beams reflected by the optical disc 26 pass through the optical signal detector and amplifier (PDIC) 254 to generate optical-to-electrical signals A, B, C, D, E, F, G, H. The optical-to-electrical signals A, B, C, and D are signals of the main beam, the optical-to-electrical signals F and G are signals of the first auxiliary beam, and the optical-to-electrical signals E and H are signals of the second auxiliary beam. The positions corresponding to the optical-to-electrical signals A, B, C, D, E, F, G, and H are as shown in FIG. 2 .

图3所示为图2的数字信号处理器23的方块图。如该图所示，数字信号处理器23包含电子信号偏移量校正模块231、特征抽取器232、增益计算单元233、以及控制波形产生器234。电子信号偏移量校正模块231用来校正前级放大器21的主要光束的OP放大器211与辅助光束的OP放大器212的电子信号偏移量MPP_offset与SPP_offset。特征抽取器232用来抽取主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’中与透镜偏移或旋转有关的分量。例如，在透镜偏移一距离时(即步进移动)时，主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’的特征为直流分量，或者透镜产生固定频率的三角波位移，主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’的特征可为平均值。FIG. 3 is a block diagram of the digital signal processor 23 of FIG. 2 . As shown in the figure, the digital signal processor 23 includes an electronic signal offset correction module 231 , a feature extractor 232 , a gain calculation unit 233 , and a control waveform generator 234 . The electronic signal offset correction module 231 is used for correcting the electronic signal offsets MPP_offset and SPP_offset of the OP amplifier 211 of the main beam and the OP amplifier 212 of the auxiliary beam of the preamplifier 21 . The feature extractor 232 is used for extracting components related to lens shift or rotation in the push-pull signal MPP' of the main beam and the push-pull signal SPP' of the auxiliary beam. For example, when the lens is shifted by a certain distance (that is, stepping movement), the push-pull signal MPP' of the main beam and the push-pull signal SPP' of the auxiliary beam are characterized by a DC component, or the lens produces a fixed-frequency triangular wave displacement, the main The characteristic of the push-pull signal MPP' of the beam and the push-pull signal SPP' of the auxiliary beam may be an average value.

增益计算单元233根据特征抽取器232所抽取的特征计算辅助光束的OP放大器相对于主要光束的OP放大器的增益α。而控制波形产生器234则根据控制波形参数输出控制波形信号给物镜运动致动器24，用于控制物镜253移动或转动至所需要的位置。因此，该数字信号处理器23可根据前级放大器21所输出的主要光束的推挽信号MPP’与辅助光束的推挽信号SPP’来计算出前级放大器21所需要的参数，以及控制物镜的移动。The gain calculation unit 233 calculates the gain α of the OP amplifier of the auxiliary beam relative to the OP amplifier of the main beam according to the features extracted by the feature extractor 232 . The control waveform generator 234 outputs a control waveform signal to the objective lens movement actuator 24 according to the control waveform parameters for controlling the objective lens 253 to move or rotate to a desired position. Therefore, the digital signal processor 23 can calculate the parameters required by the pre-amplifier 21 according to the push-pull signal MPP' of the main beam and the push-pull signal SPP' of the auxiliary beam output by the pre-amplifier 21, and control the movement of the objective lens .

另外，图4显示本发明差动推挽式寻轨误差信号的校正系统的另一实施例。该实施例与图2所示的校正系统最大差别是前级放大器21’将第一辅助光束13的光转电信号F、G和第二辅助光束14的光转电信号E、H分别经由放大器214’、212’、215’、213’差动放大后再合并。合并后的信号再经由放大器216’与主要光束的推挽信号MPP’差动放大后输出为DPP。而数字信号处理器23’的架构与数字信号处理器23的架构相同，不同点为数字信号处理器23’必须多产生SPP2_offset。In addition, FIG. 4 shows another embodiment of the differential push-pull tracking error signal correction system of the present invention. The biggest difference between this embodiment and the correction system shown in FIG. 2 is that the pre-amplifier 21' converts the light-to-electricity signals F, G of the first auxiliary beam 13 and the light-to-electricity signals E, H of the second auxiliary beam 14 respectively through the amplifier 214', 212', 215', 213' are combined after differential amplification. The combined signal is differentially amplified by the amplifier 216' and the push-pull signal MPP' of the main beam, and then output as DPP. The structure of the digital signal processor 23' is the same as that of the digital signal processor 23, the difference is that the digital signal processor 23' must generate more SPP2_offset.

以下参考图5与图6说明本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法。图5所示为本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法的数学证明的流程图。图6所示为本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法的实施例的流程图。本发明增益校正方法不需考虑A_s1、A_s2、Q₁、Q₂的值，亦不需知道Q/P，即可计算出正确的辅助光束的OP放大器的增益α。该校正方法取得两次透镜不同的偏移量(lens-shift)或旋转量(lens-tilt)所产生的推挽信号的特征值，利用该等特征值的运算即可获得增益α。本发明实施例的透镜偏移量或旋转量采用步进响应(Step response)的方式，因此推挽信号的特征值为直流分量。参考图3，本发明的数学证明的流程图如下：Referring to FIG. 5 and FIG. 6 , the gain correction method for the differential push-pull tracking error in the optical disc access system of the present invention will be described below. FIG. 5 is a flow chart of the mathematical proof of the differential push-pull tracking error gain correction method in the optical disc access system of the present invention. FIG. 6 is a flow chart of an embodiment of a differential push-pull tracking error gain correction method in an optical disc access system of the present invention. The gain correction method of the present invention can calculate the correct gain α of the OP amplifier of the auxiliary beam without considering the values of A _s1 , A _s2 , Q ₁ , and Q ₂ , and without knowing Q/P. The correction method obtains the eigenvalues of the push-pull signals generated by the different lens-shifts or lens-tilts of the two lenses, and the gain α can be obtained by operation of the eigenvalues. The lens offset or rotation in the embodiment of the present invention adopts a step response (Step response), so the characteristic value of the push-pull signal is a DC component. With reference to Fig. 3, the flow chart of mathematical proof of the present invention is as follows:

步骤S502：调整电路的OFFSET值C_m、C_s1与C_s2为0；当然该步骤亦可省略。Step S502: Adjust the OFFSET values C _m , C _s1 and C _s2 of the circuit to 0; of course, this step can also be omitted.

步骤S504：致动透镜，利用数字信号处理器23所输出的控制波形信号，使物镜致动器24移动或旋转透镜253，使该透镜253形成第一偏移量tilt1。Step S504 : actuate the lens, and use the control waveform signal output by the digital signal processor 23 to make the objective lens actuator 24 move or rotate the lens 253 so that the lens 253 forms a first offset tilt1 .

步骤S506：计算第一偏移量tilt1下的主要光束推挽信号MPP(tilt1)与辅助光束推挽信号SPP(tilt1)值。根据式(2)与式(3)产生第一偏移量tilt1下的MPP(tilt1)与SPP(tilt1)值，如式(7)与式(8)所示。Step S506: Calculate the values of the main beam push-pull signal MPP(tilt1) and the auxiliary beam push-pull signal SPP(tilt1) at the first offset tilt1. The values of MPP(tilt1) and SPP(tilt1) under the first offset tilt1 are generated according to formula (2) and formula (3), as shown in formula (7) and formula (8).

$MPP MPP ((tilt tilt 11)) = = {A A}_{m m} \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P})) + + {A A}_{m m} \cdot &Center Dot; K K ((tilt tilt 11)) + + {C C}_{m m} - - - - - - ((77))$

$SPP SPP ((tilt tilt 11)) = = (({A A}_{S S 11} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{11}}{P P})) + + {A A}_{S S 22} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{22}}{P P})))) \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{S S 22} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{22}}{P P})) - - {A A}_{S S 11} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{11}}{P P})))) \cdot \cdot cos cos ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{S S 11} + + {A A}_{S S 22})) \cdot \cdot K K ((tilt tilt 11)) + + (({C C}_{S S 11} + + {C C}_{S S 22}))$

(8)(8)

步骤S508：抽取第一偏移量tilt1下的MPP(tilt1)与SPP(tilt1)的特征值(DC值)。亦即滤掉式(7)与式(8)的AC分量，其DC值如式(9)与式(10)所示。Step S508 : Extract the characteristic values (DC values) of MPP(tilt1 ) and SPP(tilt1 ) under the first offset tilt1t1 . That is to filter out the AC component of formula (7) and formula (8), and its DC value is shown in formula (9) and formula (10).

DC{MPP(tilt1)}＝A_m·K(tilt1)+C_m (9)DC{MPP(tilt1)}=A _m K(tilt1)+C _m (9)

DC{SPP(tilt1)}＝(A_S1+A_S2)·K(tilt1)+(C_S1+C_S2) (10)DC{SPP(tilt1)}＝(A _S1 +A _S2 )·K(tilt1)+(C _S1 +C _S2 ) (10)

步骤S510：再致动一次透镜，使透镜形成第二偏移量tilt2。Step S510: actuate the lens again to make the lens form a second offset tilt2.

步骤S512：计算第二偏移量tilt2下的MPP(tilt2)与SPP(tilt2)值。根据式(2)与式(3)产生第二偏移量tilt2下的MPP(tilt2)与SPP(tilt2)值，如式(11)与式(12)所示。Step S512: Calculate the MPP(tilt2) and SPP(tilt2) values under the second offset tilt2. The values of MPP(tilt2) and SPP(tilt2) under the second offset tilt2 are generated according to formula (2) and formula (3), as shown in formula (11) and formula (12).

$MPP MPP ((tilt tilt 22)) = = {A A}_{m m} \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P})) + + {A A}_{m m} \cdot &Center Dot; K K ((tilt tilt 22)) + + {C C}_{m m} - - - - - - ((1111))$

$SPP SPP ((tilt tilt 22)) = = (({A A}_{S S 11} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{11}}{P P})) + + {A A}_{S S 22} \cdot &Center Dot; cos cos ((\frac{{22 πQ πQ}_{22}}{P P})))) \cdot &Center Dot; sin sin ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{S S 22} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{22}}{P P})) - - {A A}_{S S 11} \cdot \cdot sin sin ((\frac{{22 πQ πQ}_{11}}{P P})))) \cdot &Center Dot; cos cos ((\frac{22 πx πx}{P P}))$

$+ + (({A A}_{S S 11} + + {A A}_{S S 22})) \cdot &Center Dot; K K ((tilt tilt 22)) + + (({C C}_{S S 11} + + {C C}_{S S 22}))$

(12)(12)

步骤S514：抽取第二偏移量tilt2下的MPP(tilt2)与SPP(tilt2)的特征值(DC值)。亦即滤掉式(11)与式(12)的AC分量，其DC值如式(13)与式(14)所示。Step S514 : Extract the characteristic values (DC values) of MPP(tilt2 ) and SPP(tilt2 ) under the second offset tilt2. That is to filter out the AC components of Equation (11) and Equation (12), and their DC values are shown in Equation (13) and Equation (14).

DC{MPP(tilt2)}＝A_m·K(tilt2)+C_m (13)DC{MPP(tilt2)}=A _m K(tilt2)+C _m (13)

DC{SPP(tilt2)}＝(A_S1+A_S2)·K(tilt2)+(C_S1+C_S2) (14)DC{SPP(tilt2)}＝(A _S1 +A _S2 )·K(tilt2)+(C _S1 +C _S2 ) (14)

步骤S516：计算在第一偏移量tilt1与第二偏移量tilt2场合下的MPP与SPP的DC偏移量MD与SD。如式(15)与式(16)所示。Step S516 : Calculate the DC offsets MD and SD of the MPP and SPP in the case of the first offset tilt1 and the second offset tilt2 . As shown in formula (15) and formula (16).

MD＝DC{MPP(tilt2)}-DC{MPP(tilt1)}＝A_m·{K(tilt2)-K(tilt1)} (15)MD=DC{MPP(tilt2)}-DC{MPP(tilt1)}=A _m {K(tilt2)-K(tilt1)} (15)

SD＝DC{SPP(tilt2)}-DC{SPP(tilt1)}＝(A_s1+A_s2)·{K(tilt2)-K(tilt1} (16)SD=DC{SPP(tilt2)}-DC{SPP(tilt1)}=(A _s1 +A _s2 )·{K(tilt2)-K(tilt1} (16)

步骤S518：定义并计算 $α = \frac{MD}{SD} = \frac{A_{m}}{A_{s 1} + A_{s 2}},$ 且将该式带入式(4)，即可获得式(17)。Step S518: Define and calculate $α = \frac{MD}{SD} = \frac{A_{m}}{A_{thes 1} + A_{the s 2}},$ And bring this formula into formula (4) to get formula (17).

$TE TE = = MPP MPP - - α α \cdot &Center Dot; SPP SPP$

$= = (({A A}_{m m} - - \frac{{A A}_{m m}}{{A A}_{s the s 11} + + {A A}_{s the s 22}} \cdot &Center Dot; (({A A}_{s the s 11} \cdot \cdot cos cos ((\frac{{22 πQ πQ}_{11}}{P P})) + + {A A}_{s the s 22} \cdot \cdot cos cos ((\frac{{22 πQ πQ}_{22}}{P P})))))) \cdot \cdot sin sin ((\frac{22 πx πx}{P P}))$

$- - α α \cdot &Center Dot; (({A A}_{s the s 22} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{22}}{P P})) - - {A A}_{s the s 11} \cdot &Center Dot; sin sin ((\frac{{22 πQ πQ}_{11}}{P P})))) \cdot &Center Dot; cos cos ((\frac{22 πx πx}{P P}))$

$+ + 00 \cdot &Center Dot; K K ((tilt tilt)) + + (({C C}_{m m} - - α α \cdot &Center Dot; (({C C}_{S S 11} + + {C C}_{S S 22}))))$

(17)(17)

因此，根据式(17)即可发现寻轨误差信号TE与K(tilt)变数无关，亦即寻轨误差信号TE并不受光学读取头的倾斜或透镜偏移影响。而且，本发明的方法并不需要知道P/Q的比例，以及限制A_s1、A_s2、Q₁、Q₂的值。所以，只要计算出第一偏移量tilt1与第二偏移量tilt2场合下的MPP与SPP的DC偏移量MD与SD，即可计算出辅助光束的OP放大器的增益值α。Therefore, according to equation (17), it can be found that the tracking error signal TE has nothing to do with the K(tilt) variable, that is, the tracking error signal TE is not affected by the tilt of the optical pickup head or the lens shift. Moreover, the method of the present invention does not need to know the ratio of P/Q, and limits the values of A _s1 , A _s2 , Q ₁ , and Q ₂ . Therefore, as long as the DC offsets MD and SD of the MPP and SPP are calculated in the case of the first offset tilt1 and the second offset tilt2, the gain value α of the OP amplifier of the auxiliary beam can be calculated.

上述流程图是用来说明本发明校正方法的原理，而图6为本发明光盘存取系统中的差动推挽式寻轨误差的增益校正方法的实施例的流程图。该实施例的透镜偏移量或旋转量采用步进响应的方式，因此推挽信号的特征值为直流分量。当然，透镜偏移量或旋转量亦可采用连续变化的波形响应。以下参考图6说明该流程图的步骤。The above flow chart is used to illustrate the principle of the correction method of the present invention, and FIG. 6 is a flow chart of an embodiment of the differential push-pull tracking error gain correction method in the optical disc access system of the present invention. The lens offset or rotation in this embodiment adopts a step response method, so the eigenvalue of the push-pull signal is a DC component. Of course, the lens offset or rotation can also adopt a continuously changing waveform response. The steps of this flowchart are described below with reference to FIG. 6 .

步骤S602：开启电源且关闭激光光源。在此情形下，由数字信号处理器23所测得的MPP与SPP信号为前级放大器21与光学信号检测与放大器254的电子信号偏移量。Step S602: Turn on the power and turn off the laser light source. In this case, the MPP and SPP signals measured by the digital signal processor 23 are electronic signal offsets of the pre-amplifier 21 and the optical signal detection and amplifier 254 .

步骤S604：校准MPP_offset值。在步骤S602的情形下，由数字信号处理器23测量MPP值，并产生MPP_offset给前级放大器21的主要光束放大器211。Step S604: Calibrate the MPP_offset value. In the case of step S602 , the digital signal processor 23 measures the MPP value, and generates MPP_offset for the main beam amplifier 211 of the preamplifier 21 .

步骤S606：校准SPP_offset值。在步骤S602的情形下，由数字信号处理器23测量SPP值，并产生SPP_offset给前级放大器21的辅助光束放大器212。Step S606: Calibrate the SPP_offset value. In the case of step S602 , the digital signal processor 23 measures the SPP value, and generates SPP_offset for the auxiliary beam amplifier 212 of the preamplifier 21 .

步骤S608：启动激光光源，并聚焦光束。Step S608: Start the laser light source and focus the light beam.

步骤S610：启动主轴电机(spindle motor)。驱动主轴电机以转动光盘片，并产生MPP、SPP与TE的偏心跨轨量。此时，主轴电机可控制在定角速度(CAV)或定线速度(CLV)控制模式，藉以保持光盘片旋转。Step S610: Start the spindle motor. Drive the spindle motor to rotate the optical disk, and generate the eccentric track crossing amount of MPP, SPP and TE. At this time, the spindle motor can be controlled in a constant angular velocity (CAV) or constant linear velocity (CLV) control mode, so as to keep the optical disk rotating.

步骤S612：设定初值α。设定前级放大器21的辅助光束放大器212的增益初值。Step S612: Set an initial value α. The initial gain value of the auxiliary beam amplifier 212 of the preamplifier 21 is set.

步骤S614：控制透镜至一偏移位置。利用数字信号处理器23所输出的控制波形信号，使物镜致动器24移动或旋转透镜253，使该透镜253形成偏移或旋转。Step S614: Control the lens to an offset position. Using the control waveform signal output by the digital signal processor 23, the objective lens actuator 24 moves or rotates the lens 253, so that the lens 253 is shifted or rotated.

步骤S616：测量特征值。在透镜稳定后，以数字信号处理器23测量MPP的特征值MD、以及SPP的DC特征值SD。测量方法可利用测量峰对峰值后，将峰值与谷值相加后除以2，或是直接以低通滤波器(low-pass filter)直接取得特征值。Step S616: Measure feature values. After the lens is stabilized, the characteristic value MD of MPP and the characteristic value SD of DC of SPP are measured by the digital signal processor 23 . The measurement method can be to measure the peak-to-peak value, add the peak value and the valley value and divide by 2, or directly obtain the characteristic value directly with a low-pass filter.

步骤S618：设定新的α值。新的α值定义为 $α = \frac{MD}{SD} .$ Step S618: Set a new α value. The new value of α is defined as $α = \frac{MD}{SD} .$

步骤S620：结束。Step S620: end.

图5与图6的原理与实施例的流程图的差别是该原理直接取得两次物镜偏移量(lens-shift)所对应的MPP与SPP的DC偏移值来计算SPP的OP放大器的增益(SPPG)，藉以证明该方法的可行性，而实施例是将初值的DC值来作为第一偏移量的MPP与SPP的第一DC值，且调整为0，而以另一偏移量tilt的MPP与SPP的DC偏移值作为第二DC值，进而计算出SPP的OP放大器的增益(SPPG)。The difference between the principle of Fig. 5 and Fig. 6 and the flowchart of the embodiment is that the principle directly obtains the DC offset value of MPP and SPP corresponding to the objective lens offset (lens-shift) twice to calculate the gain of the OP amplifier of SPP (SPPG), in order to prove the feasibility of the method, and the embodiment is to use the DC value of the initial value as the first DC value of the MPP and SPP of the first offset, and adjust it to 0, and use another offset The DC offset value between the MPP and the SPP of tilt is used as the second DC value, and then the gain (SPPG) of the OP amplifier of the SPP is calculated.

以上虽以实施例说明本发明，但并不因此限定本发明的范围，只要不脱离本发明的要旨，本领域内的普通技术人员可进行各种变形或变更。例如，实施例中以MD/SD来计算最佳增益比值，但也可利用通过各种不同的增益比值，从中选取MD＝SD时的增益作为最佳设定值。又例如物镜或盘片的控制方式、控制波形、特征信号的抽取方式等，实施例中以步进控制输入(Step input)并取DC值分量以进行校正，但也可利用与RUNOUT频率区域不同的低频正弦波、方波、锯齿波作为控制输入，并抽取MPP与SPP于该控制频率的分量作为特征值。Although the present invention has been described above with examples, the scope of the present invention is not limited thereto. Those skilled in the art can make various modifications or changes as long as they do not depart from the gist of the present invention. For example, in this embodiment, MD/SD is used to calculate the optimal gain ratio, but various gain ratios can also be used to select the gain when MD=SD as the optimal setting value. Another example is the control method of the objective lens or the disk, the control waveform, the extraction method of the characteristic signal, etc. In the embodiment, the step input is used to control the input (Step input) and the DC value component is used for correction, but it can also be used differently from the RUNOUT frequency region. The low-frequency sine wave, square wave, and sawtooth wave are used as control inputs, and the components of MPP and SPP at the control frequency are extracted as eigenvalues.

Claims

1. A differential push-pull tracking error gain correction method in an optical disc access system, which is used to correct the ratio of the amplifier gain of the auxiliary light beam to the amplifier gain of the main light beam. The gain correction method comprises the following steps:

Turn on the laser light source and focus the beam;

Start the spindle motor;

controlling the objective lens and the optical disc to be in a first relative change state;

Measuring the eigenvalue of the push-pull signal of the main beam related to the objective lens offset as the first main beam eigenvalue;

Measuring the eigenvalue of the push-pull signal of the auxiliary beam related to the offset of the objective lens as the first eigenvalue of the auxiliary beam;

controlling the objective lens and the optical disc to be in a second relative change state;

Measuring the eigenvalue of the push-pull signal of the main beam related to the objective lens offset as the second main beam eigenvalue;

Measuring the characteristic value of the push-pull signal of the auxiliary beam related to the objective lens offset as the second auxiliary beam characteristic value; and

Calculating a gain, calculating a gain ratio of the auxiliary beam relative to the main beam according to the first main beam eigenvalue, the first auxiliary beam eigenvalue, the second main beam eigenvalue, and the second auxiliary beam eigenvalue.

2. The gain correction method for differential push-pull tracking error as claimed in claim 1, wherein the aforementioned gain ratio is approximately:

(second main beam eigenvalue−first main beam eigenvalue)/(second auxiliary beam eigenvalue−first auxiliary beam eigenvalue).

3. The gain correction method for differential push-pull tracking error as claimed in claim 1, wherein the first relative change state is that the objective lens and the optical disc are kept at a first fixed angle and position.

4. The gain correction method for differential push-pull tracking error as claimed in claim 3, wherein the second relative change state is that the objective lens and the optical disc are kept at a second fixed angle and position.

5. The gain correction method for differential push-pull tracking error as claimed in claim 4, wherein the characteristic value of the main beam is a DC component of the push-pull signal of the main beam.

6. The gain correction method for differential push-pull tracking error as claimed in claim 5, wherein the characteristic value of the auxiliary beam is a DC component of the push-pull signal of the auxiliary beam.

7. A differential push-pull tracking error gain correction method in an optical disc access system, which is used to correct the ratio of the amplifier gain of the auxiliary beam to the amplifier gain of the main beam. The gain correction method includes the following steps:

Turn on the power and turn off the laser light source;

Calibrate the circuit signal offset of the main beam amplifier, that is, set the circuit signal offset of the main beam amplifier in the radio frequency IC, so that the output of the amplifier is the first main beam characteristic value;

Calibrate the circuit signal offset of the auxiliary beam amplifier, that is, set the circuit signal offset of the auxiliary beam amplifier in the radio frequency IC, so that the output of the amplifier is the first auxiliary beam characteristic value;

Turn on the laser light source and focus the beam;

Start the spindle motor;

Change the relative offset value of the lens and the disc;

Measuring an eigenvalue of the push-pull signal of the main beam related to the objective lens offset as a second main beam eigenvalue;

Calculating the gain is to calculate the gain ratio of the auxiliary beam relative to the main beam according to the first main beam eigenvalue, the first auxiliary beam eigenvalue, the second main beam eigenvalue, and the second auxiliary beam eigenvalue.

8. The gain correction method for differential push-pull tracking error as claimed in claim 7, wherein the aforementioned gain ratio is approximately:

9. The gain correction method for differential push-pull tracking error as claimed in claim 7, wherein the eigenvalue of the first main beam is zero.

10. The gain correction method for differential push-pull tracking error according to claim 9, wherein the eigenvalue of the first auxiliary beam is zero.

11. The gain correction method for differential push-pull tracking error as claimed in claim 10, wherein the aforementioned gain ratio is approximately:

Second main beam eigenvalue/second auxiliary beam eigenvalue.

12. A differential push-pull tracking error gain correction device in an optical disc access system, used to correct the ratio of the amplifier gain of the auxiliary beam to the amplifier gain of the main beam, the gain correction device comprising:

An optical signal amplifier, which receives the signals reflected by the main beam and the auxiliary beam through the optical disc, amplifies and outputs the radio frequency signal of the main beam and the radio frequency signal of the auxiliary beam;

A radio frequency receiver differentially amplifies the main beam radio frequency signal and the auxiliary beam radio frequency signal of the aforementioned optical signal amplifier through the front stage, and then differentially amplifies the amplified signals through the main beam signal amplifier and the auxiliary beam signal amplifier to generate The main beam push-pull signal and the auxiliary beam push-pull signal, and output the difference between the main beam push-pull signal and the auxiliary beam push-pull signal as a differential push-pull tracking error signal;

An analog-to-digital converter, receiving the main beam push-pull signal and the auxiliary beam push-pull signal of the aforementioned radio frequency receiver, and generating a digital main beam push-pull signal and a digital auxiliary beam push-pull signal; and

A digital signal processor, receiving the aforementioned digital main beam push-pull signal and digital auxiliary beam push-pull signal, and using a feature extractor to extract the eigenvalues of the digital main beam push-pull signal and digital auxiliary beam push-pull signal, and through A gain calculation module calculates the gain ratio of the auxiliary beam signal amplifier of the radio frequency receiver relative to the main beam signal amplifier according to the characteristic value of the push-pull signal.

13. The gain correction device for differential push-pull tracking error as claimed in claim 12, wherein said digital signal processor further has a control waveform generator for generating control signals to the objective lens driver according to control waveform parameters.

14. The gain correction device for differential push-pull tracking error as claimed in claim 13, wherein the objective lens driver is used to control the relative position and angle of the objective lens and the optical disc.

15. The gain correction device for differential push-pull tracking error as claimed in claim 12, wherein said digital signal processor also has a circuit signal offset correction module comprising an amplifier, which is used to push The pull signal and the digital auxiliary beam push-pull signal are used to calculate the circuit signal offset of the main beam signal amplifier and the auxiliary beam signal amplifier, and output the circuit signal offset of the amplifier to the radio frequency receiver.

16. The gain correction device for differential push-pull tracking error as claimed in claim 12, wherein said feature extractor extracts the relative position and Angle-affected signal.

17. A gain correction method for a differential push-pull tracking error in an optical disc access system, which is used to correct the ratio of the amplifier gain of the auxiliary beam to the amplifier gain of the main beam. The gain correction method includes the following steps:

Turn on the laser light source and focus the beam;

Start the spindle motor;

controlling the objective lens and the disc to be in a first relative change state;

The gain ratio of the auxiliary beam relative to the main beam is adjusted so that the difference between the second main beam eigenvalue and the first main beam eigenvalue is close to the difference between the second auxiliary beam eigenvalue and the first auxiliary beam eigenvalue.

18. The gain correction method for differential push-pull tracking error as claimed in claim 17, wherein the first relative change state is that the objective lens and the disk are kept at a first fixed angle and position.

19. The gain correction method for differential push-pull tracking error as claimed in claim 18, wherein the second relative change state is that the objective lens and the disk are kept at a second fixed angle and position.

20. The gain correction method for differential push-pull tracking error as claimed in claim 19, wherein the characteristic value of the main beam is a DC component of the push-pull signal of the main beam.

21. The gain correction method for differential push-pull tracking error as claimed in claim 20, wherein the characteristic value of the auxiliary beam is a DC component of the push-pull signal of the auxiliary beam.