JP4296869B2 - Optical pickup and optical disk recording / reproducing apparatus - Google Patents

Description

The present invention relates to, for example, an optical pickup for reproducing data stored on an optical disc and an optical disc recording / reproducing apparatus using the optical pickup.

  Conventionally, as a technology for canceling noise of a laser beam from a light source of an optical pickup of an optical disk recording / reproducing apparatus, a light receiving element that receives reflected light obtained by reflection on an optical disk and a light receiving element that receives light without reflecting on an optical disk are provided. A method is adopted in which a monitor output signal for APC (Automatic Power Control) from a light receiving element that receives light without being reflected is subtracted from a reproduction high-frequency signal (reproduced RF signal) that is provided separately and receives the reflected light. ing.

Also, an FPD (Front Photo Detector) for generating a monitor output signal for APC is provided separately from an RF PD (RF Photo Detector) for generating a reproduction RF signal, and both an additive noise component and a modulation noise component of laser noise are provided. There are some that can be canceled. (For example, refer to Patent Document 1.)
JP 2002-183970 (paragraphs [0029], [0030] and [0074], FIG. 1)

  However, in recent years, the recorded domain has become smaller with the increase in the density of optical discs. Therefore, in order to ensure a stable READ operation during reproduction of a DVD or the like, tracking is performed using each output signal of a quadrant PD of the main spot. A DPD (Differential Phase Detection) method for detecting an error is used. However, the technique of Patent Document 1 can improve the signal-to-noise ratio for the RF signal, but it can improve the signal-to-noise ratio (signal-to-noise ratio) of the signal from each region of the quadrant PD of the main spot, for example. Since there is no signal-to-noise ratio, the tracking error signal is of poor quality and cannot be reproduced properly.

  Further, in the technique of Patent Document 1, the FPD and the quadrant PD are configured separately, and the FPD signal and the reproduction RF signal are processed by different PDICs (Photo Detector ICs), for example, process variations. In addition, due to the difference in the group delay characteristics of the two signals, sufficient LD noise cancellation in a wide band is impossible.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical pickup excellent in tracking performance and an optical disc recording / reproducing apparatus using the optical pickup .

  In order to achieve the above object, an optical pickup according to a main aspect of the present invention includes a light source that irradiates an optical disc with laser light and a plurality of regions that receive the reflected light of the laser light from the optical disc. 1 light receiving element, a second light receiving element that is disposed in the vicinity of the first light receiving element and directly receives the laser light from the light source, and each of the first light receiving elements generated in each region of the first light receiving element. First arithmetic means for subtracting the signal of the second light receiving element from the signal, and second arithmetic means for adding signals respectively shunted from the respective signals generated in the respective regions of the first light receiving element; And third calculating means for subtracting the signal of the second light receiving element from the signal generated by addition by the second calculating means.

  Here, “directly receiving light” means that the light is not reflected on the optical disk, for example, by irradiating the second light receiving element with laser light emitted from a light source via a grating or a beam splitter to receive light. It is.

  In the present invention, since the first arithmetic means can subtract the signal of the second light receiving element from each signal generated in each region of the first light receiving element, for example, each of the first light receiving elements. It is possible to remove the noise component in each signal generated in the region and improve the tracking performance. Further, since the signal from the second light receiving element can be subtracted from the signal generated by the addition by the second arithmetic means by the third arithmetic means, the quality of the reproduction signal can be improved, for example.

  According to an aspect of the present invention, the first light receiving element and the second light receiving element are disposed on the same chip. As a result, signal process variation can be reduced, and broadband laser noise can be canceled.

  According to one aspect of the present invention, a signal from the second light receiving element, each signal generated in each region of the first light receiving element, and each signal generated in each region of the first light receiving element. The delay characteristics of the signals generated by addition by the second calculation means are the same. Thereby, since the influence by the difference in a delay characteristic can be suppressed, a noise component can be removed more correctly.

  According to one aspect of the present invention, the signal between the signal generated from each region of the first light receiving element and added by the second calculation means and the signal from the second light receiving element is provided. The delay error is 0.5 ns or less, and the delay error between each signal generated in each region of the first light receiving element and the signal from the second light receiving element is 1 ns or less. . As a result, a sufficient amount of noise cancellation can be ensured.

  An optical pickup according to another aspect of the present invention includes a light source that irradiates an optical disc with laser light, a first light receiving element that is divided into a plurality of regions that receive reflected light of the laser light from the optical disc, A second light receiving element that is disposed in the vicinity of the first light receiving element and directly receives the laser light from the light source, and the second light receiving from each signal generated in each region of the first light receiving element. The first arithmetic means for subtracting the signal of each element and the second arithmetic means for adding the respective signals generated by the first arithmetic means are provided.

  In the present invention, since the first arithmetic means can subtract the signal of the second light receiving element from each signal generated in each region of the first light receiving element, for example, each of the first light receiving elements. It is possible to improve the tracking performance by removing the laser noise component in each signal generated in the region.

  According to an aspect of the present invention, the first light receiving element and the second light receiving element are disposed on the same chip. As a result, variations in signal processing can be reduced.

  According to one aspect of the present invention, the delay characteristics of the signal from the second light receiving element and each signal generated in each region of the first light receiving element are the same. Thereby, since the influence of the difference in delay characteristics can be suppressed, the noise component can be removed more accurately.

  According to an aspect of the present invention, a delay error between each signal generated in each region of the first light receiving element and a signal from the second light receiving element is 1 ns or less. And Thereby, a noise component can be removed more reliably.

  An optical disk recording / reproducing apparatus according to another aspect of the present invention includes a light source that irradiates an optical disk with laser light, a first light receiving element that is divided into a plurality of regions that receive reflected light of the laser light from the optical disk, and The second light receiving element disposed in the vicinity of the first light receiving element and directly receiving the laser beam from the light source, and the second signal generated from each signal generated in each region of the first light receiving element. First computing means for subtracting the signals of the light receiving elements, second computing means for adding signals respectively shunted from the signals generated in the respective areas of the first light receiving elements, and the second computing means And an optical pickup including a third calculation unit that subtracts the signal of the second light receiving element from the signal generated by addition by the calculation unit.

  In the present invention, the optical disc recording / reproducing apparatus can subtract the signal of the second light receiving element from the respective signals generated in the respective areas of the first light receiving element by the first calculating means. The noise component in each signal generated in each region of one light receiving element can be removed to improve the tracking performance. Further, since the signal from the second light receiving element can be subtracted from the signal generated by the addition by the second arithmetic means by the third arithmetic means, the quality of the reproduction signal can be improved, for example.

  According to an aspect of the present invention, the optical pickup is characterized in that the first light receiving element and the second light receiving element are disposed on the same chip. As a result, signal process variation can be reduced, and broadband laser noise can be canceled.

  According to an aspect of the present invention, the optical pickup includes a signal from the second light receiving element, each signal generated in each region of the first light receiving element, and the first light receiving element. The delay characteristics of the signals generated in each region and added and generated by the second calculation means are the same. Thereby, since the influence of a delay error can be suppressed, a noise component can be removed more accurately.

  According to one aspect of the present invention, a signal generated in each region of the first light receiving element of the optical pickup and added by the second calculation means and a signal from the second light receiving element And the delay error between each signal generated in each region of the first light receiving element and the signal from the second light receiving element is 1 ns or less. It is characterized by. As a result, a sufficient amount of noise cancellation can be ensured.

  An optical disk recording / reproducing apparatus according to another aspect of the present invention includes a light source that irradiates an optical disk with laser light, a first light receiving element that is divided into a plurality of regions that receive reflected light of the laser light from the optical disk, and The second light receiving element disposed in the vicinity of the first light receiving element and directly receiving the laser beam from the light source, and the second signal generated from each signal generated in each region of the first light receiving element. And an optical pickup comprising a first computing means for subtracting the signals of the light receiving elements, and a second computing means for adding the respective signals generated by the first computing means.

  In the present invention, the optical disc recording / reproducing apparatus can subtract the signal of the second light receiving element from the respective signals generated in the respective areas of the first light receiving element by the first calculating means. The noise component in each signal generated in each region of one light receiving element can be removed to improve the tracking performance.

  According to an aspect of the present invention, the optical pickup is characterized in that the first light receiving element and the second light receiving element are disposed on the same chip. As a result, variations in signal processing can be reduced.

  According to an aspect of the present invention, the optical pickup has the same delay characteristics between the signal from the second light receiving element and each signal generated in each region of the first light receiving element. It is characterized by. Thereby, since the influence of the delay characteristic can be suppressed, the noise component can be more accurately removed.

  According to one aspect of the present invention, a delay error between each signal generated in each region of the first light receiving element of the optical pickup and the signal from the second light receiving element is 1 ns or less. It is characterized by being. Thereby, a noise component can be removed more reliably.

  A chip according to another aspect of the present invention includes a first light receiving element that is divided into a plurality of regions that receive reflected light from an optical disc, and a laser that is disposed in the vicinity of the first light receiving element. A second light receiving element that directly receives light is provided. Thereby, process variations of signals from the first light receiving element and the second light receiving element can be reduced.

  As described above, according to the present invention, the tracking performance can be easily improved and the quality of the reproduction signal can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments, the description will focus on the reproduction of CDs and DVDs of an optical disk recording / reproducing apparatus using an optical pickup, but the present invention is not limited to this.

  1 is a block diagram of an optical disk recording / reproducing apparatus according to a first embodiment of the present invention, FIG. 2 is a schematic explanatory diagram of an optical pickup, FIG. 3 is a schematic diagram of a photodetector IC (PDIC) of the optical pickup, and FIG. FIG. 5 is a graph showing the group delay (error) characteristics between the LNC effect amount and the frequency.

  As shown in FIG. 1, an optical disc recording / reproducing apparatus 1 has an optical disc 2 on which, for example, music information or video information is recorded, a spindle motor 3 for rotating the optical disc 2, and a laser beam on the optical disc 2. An optical pickup unit 4 that converts an electrical signal, a driver 5 that drives the spindle motor 3 and the like, and a driver control unit 6 that controls the driver 5, for example, music such as RF signal demodulation, error detection, and correction A signal processing unit 9 that reproduces a signal such as information or generates a tracking signal, etc., a D / A converter 10 that converts the signal from the signal processing unit 9 into an analog signal, and is converted into an analog signal by the D / A converter 10 The input / output unit 1 converts the output signal into acoustic information and outputs the information, and inputs operation information using operation buttons and the like. The recording control circuit 12 includes an encoding processing means (not shown) such as acoustic information input from the input / output unit 11 and a modulation circuit, and the control unit 13 that controls the operation of the entire optical disc recording / reproducing apparatus 1. Yes.

  Here, the optical disc 2 is a recording medium such as a CD (Compact Disc) on which acoustic information or the like is recorded, or a DVD (Digital Versatile Disc) on which video information or the like is recorded.

  As shown in FIG. 1, the optical pickup unit 4 includes an optical pickup 34 that receives laser light, an amplifier 7 that amplifies the FPD signal and the PD signal from the optical pickup 34, and noise cancellation of the FPD signal and the PD signal. And a noise canceling circuit 8 that performs such processing. The noise refers to a noise component included when the semiconductor laser element 14 emits laser light.

  As shown in FIG. 2, the optical pickup unit 4 includes, for example, a semiconductor laser element (light source) 14 that emits laser light, a grating 15 that diffracts and separates the laser light into three beams, and irradiates the optical disc 2 with the separated three beams. A beam splitter 16 that separates the laser beam to be emitted into a laser beam that is not irradiated onto the optical disc 2, a collimator lens 17 that collimates the laser beam that has passed through the beam splitter 16, and a laser beam that has been collimated by the collimator lens 17. An objective lens 18 that focuses light, a grating 15, a mirror 19 that irradiates a predetermined light receiving element with laser light refracted by the beam splitter 16, and reflected light from the optical disk 2 is refracted and incident by the beam splitter 16. A detection lens 20 constituted by a cylindrical lens; In addition, a quadrant PD (first light receiving element) 22 that receives the laser light from the detection lens 20 and an FPD (second light receiving element) described later that receives the laser light reflected by the mirror 19 via the detection lens 20. 24 have a photodetector IC (hereinafter referred to as PDIC) 23 mounted on the substrate 21. The optical pickup 34 excludes the amplifier 7, an arithmetic circuit (hereinafter referred to as “SUM”) for adding four signals from a quadrant PD 22 (to be described later) and the noise cancellation circuit 8 in the optical pickup unit 4. Part.

  The semiconductor laser element 14 emits laser light having a wavelength of 780 nm, for example. The grating 15 is a diffraction grating for separating the laser light emitted from the semiconductor laser element 14 into three beams, one main beam and two sub beams.

  Further, the beam splitter 16 can transmit a part of the laser light from the grating 15 as it is and refract the remaining light in the direction of the mirror 19, and the transmitted laser light is reflected back to the optical disc 2 and returned. When it comes, it can refract all or most of the reflected light.

  Further, the mirror 19 is for irradiating the laser beam from the grating 15 refracted by the beam splitter 16 to the FPD 24 on the PDIC 23 disposed on the opposite side of the mirror 19 with respect to the beam splitter 16. By adjusting the installation angle of the mirror 19, the laser light from the semiconductor laser element 14 is irradiated to the FPD 24. The PDIC 23 includes a four-part PD 22 that receives reflected light from the optical disc 2 and an FPD 24 that receives the reflected light without being reflected by the optical disc 2 on a single substrate 21.

  Next, the PDIC 23 will be described with reference to FIGS. As shown in FIG. 3, the PDIC 23 is divided into four areas A to D, divided into four divided PDs 22, divided into two divided PDs 28 and 30, and an FPD that generates a monitor output signal for APC ( Front Photo Detector) 24, 4-division PD 22, amplifier 7 for amplifying the output from FPD 24, SUM 39 for adding the outputs from areas A to D, and 4 for removing noise components in the output signals of areas A to D And an RF-LNC circuit (hereinafter referred to as “RF-LNC”) 41 for removing noise components in the RF signal generated by addition by the laser noise cancellation circuit (hereinafter referred to as “LNC”) 38 and SUM 39. Have. Note that the FPD 24 shown in FIG. 3 is an arrangement for convenience of explanation of the circuit, and is not an actual arrangement. An actual arrangement example is shown in FIG.

  As shown in FIG. 3, the regions A to D of the four-divided PD 22 are connected to the respective I / V amplifiers 37 constituting the amplifier 7. The signal of each I / V amplifier 37 is supplied to the SUM 39 and LNC 38, respectively. The SUM 39 is connected to the RF-LNC 41. A known arithmetic circuit is used for the LNC 38 and the RF-LNC 41 constituting the noise cancellation circuit 8. The FPD 24 is connected to each LNC 38 and the RF-LNC 41 via the I / V amplifier 37. Output signals from the LNC 38 and the RF-LNC 41 are supplied to the signal processing unit 9. The two-divided PDs 28 and 30 are connected to the signal processing unit 9 via I / V amplifiers (not shown).

  As shown in FIG. 4, two-divided PDs 28 and 30 are disposed on the substrate 21 adjacent to both sides of the four-divided PD 22 in the vertical direction (Y-axis direction in FIG. 4). Further, the FPD 24 is arranged on the right side in the direction (X-axis direction in FIG. 4) orthogonal to the arrangement direction of the two-divided PDs 28 and 30 and the four-divided PD22.

  As shown in FIG. 3, the 4-division PD 22 can generate four division output signals. The four divided output signals are used for generating a tracking error signal by the DPD method. For example, since there is no pit row at the time of CD / DVD recording, tracking cannot be performed by the DPD method. Therefore, the two-part PDs 28 and 30 are used to generate a tracking error signal by the DPP (Differential Push Pull Method) method. . Further, the two-divided PDs 28 and 30 may be used for generating a tracking error signal by the three-beam method during CD reproduction.

  Further, each I / V amplifier 37 constituting the amplifier 7 amplifies the output signal from the areas A to D of the quadrant PD 22 and the output signal from the FPD 24 to a predetermined magnitude under the control of the control unit 13, for example. Can do.

  The SUM 39 can add the output signals from the regions A to D of the 4-divided PD 22 to generate an RF signal before noise removal.

  Furthermore, each LNC 38 is used for subtracting the signal of the FPD 24 from the output signal of each region A to D to remove the noise component in the output signal of each region A to D.

  Further, the RF-LNC 41 is used for subtracting the signal of the FPD 24 from the signal added and generated by the SUM 39 and removing a noise component in the signal generated and added by the SUM 39.

  The noise level of the RF-LNC 41 is set lower than that of each LNC 38. That is, the RF-LNC 41 is designed so that noise cancellation with higher accuracy than each LNC 38 is possible. Further, by mounting the FPD 24 and the four-divided PD 22 on the same substrate 21, the group delay characteristics of the FPD 24 signal, the four-divided PD regions A to D, and the RF signal are substantially the same. Has been.

  Here, the group delay characteristic represents a characteristic of a delay time from when a signal having a predetermined frequency is input to the element until it is output. A difference in group delay time in different elements is referred to as a group delay error.

Between the amount of noise cancellation (reduction) and the group delay error T, the amount of cancellation (reduction) (hereinafter referred to as “LNC effect amount”) = {(1−cos ωT) ² + (sin ωT) ² } ^{1 / When} the vertical axis is the LNC effect amount and the horizontal axis is the frequency of the laser beam, the curve E (group delay error 0.5 ns) and the curve F (group delay error 1.0 ns) shown in FIG. There is a group delay characteristic expressed.

  For example, the noise level required for DVD 16 × speed playback is about −125 dB / Hz. When an inexpensive LD with a noise level of about −100 dB / Hz is used, it is necessary to remove about 20 and 10 dB of noise in the 100 MHz band in order to reduce the noise level of the RF signal and the signal from the quadrant PD 22. There is. FIG. 5 shows that, for example, in order to reduce noise in a 100 MHz RF signal by about 20 dB, the group delay error between the RF signal and the FPD signal should be 0.5 ns or less. Further, for example, in order to reduce the noise in the signal of the 100 MHz region A to D by about 10 dB, the group delay error between the region A to D signal and the FPD signal of the quadrant PD 22 may be 1 ns or less. I understand.

  From the above, the optical pickup unit 4 is designed so that the group delay error between the RF signal and the FPD signal is 0.5 ns or less, and the group delay error between the region A to D signal of the 4-divided PD 22 and the FPD signal is 1 ns or less. ing. If the group delay error is optically possible, it is desirable that the group delay error be as close to 0 as possible.

  As shown in FIG. 1, in the signal processing unit 9, a tracking error signal and a focusing error signal are generated using the output signal from each LNC 38 from which the noise component has been removed, and at the same time, the RF-LNC 41 cancels noise. The signal is subjected to processing such as demodulation, error detection and correction, and a signal such as music information is reproduced.

  The driver 5 includes, for example, a focus driver, a tracking driver, and a spindle driver (not shown), and can move the objective lens 18 of the optical pickup 34 in the focus direction and the tracking direction. The spindle driver can control the rotation of the spindle motor 3.

  The driver control unit 6 includes, for example, a focus control circuit and a tracking control circuit (not shown). The driver control unit 6 controls the driver 5 based on a focus error signal and a tracking error signal from the signal processing unit 9 under the control of the control unit 13. Can be controlled.

  Furthermore, the input / output unit 11 includes an acoustic unit, a display unit, an imaging unit, an operation unit, and the like (not shown). For example, music converted into an analog signal supplied from the D / A converter 10 under the control of the control unit 13. Information or the like can be output as sound or the like through a speaker of the acoustic unit.

  Further, the input / output unit 11 can pass operation information from an operation button or the like of the operation unit to the control unit 13.

  Further, the control unit 13 includes, for example, a CPU (Central Processing Unit) that performs calculation and control (not shown), and a RAM (Random Access Memory) that records information temporarily as necessary to more smoothly control the optical disc recording / reproducing apparatus 1. ), A ROM (Read Only Memory), a data storage unit, and the like.

  Next, the operation of the optical disc recording / reproducing apparatus 1 configured as described above will be described focusing on the reproduction of a CD.

  First, as shown in FIG. 1, when the optical disk 2 is set in the optical disk recording / reproducing apparatus 1 and the power is turned on by a button operation of the input / output unit 11, the control unit 13 is driven by the driver control unit 6 and the driver 5 with the spindle motor 3. Is rotated at a predetermined rotational speed.

  In addition, the control unit 13 drives a thread motor (not shown) by the driver control unit 6 and the driver 5 to move the optical pickup unit 4 to a predetermined position of the optical disc 2, and the semiconductor laser element 14 by the driver control unit 6 and the driver 5. To adjust the current to the read power level.

  Further, the semiconductor laser element 14 supplied with the necessary current emits laser light having a wavelength of 780 nm, for example. The emitted laser light is first incident on the grating 15, separated into three beams, and incident on the beam splitter 16, as indicated by the solid line shown in FIG. That is, it is separated into a main beam and a sub beam by the grating 15 which is a diffraction grating, and the sub beam is diffracted so as to be irradiated to a position shifted by 1/2 track in the left-right direction of the track from the main beam for reading signals. .

  Further, a part of the laser beam composed of the three beams incident on the beam splitter 16 is transmitted as it is, and is incident on the collimator lens 17. The remainder is refracted toward the mirror 19 as shown in FIG. The laser light incident on the mirror 19 is reflected by the mirror 19 and irradiated on the FPD 24.

  On the other hand, the laser light incident on the collimator lens 17 is collimated by the collimator lens 17 and enters the objective lens 18. Then, the laser light is focused on the information recording surface of the optical disc 2 by the objective lens 18.

  Further, the laser beam composed of the three beams reflected by the information recording surface returns to the objective lens 18 and the collimator lens 17 and enters the beam splitter 16. All or part of the reflected light from the optical disk 2 incident on the beam splitter 16 is refracted and irradiated to the four-divided PD 22.

  As shown in FIG. 3, the laser light incident on the four-divided PD 22, that is, the regions A to D, is divided into four signals. Each signal is amplified by, for example, the I / V amplifier 37 under the control of the control unit 13, added by the SUM 39, and supplied to the RF-LNC 41. The four signals in the areas A to D are also supplied to each LNC 38.

  On the other hand, the laser light incident on the FPD 24 is converted into an electric signal by the FPD 24. This electric signal is amplified by the I / V amplifier 37 and supplied to each LNC 38 and RF-LNC 41.

  For example, the LNC 38 subtracts the signal of the FPD 24 from the signal of the region A to remove noise in the signal of the region A. The noise in the signals in the other regions B to D is similarly removed. The four signals from which noise has been removed in each LNC are supplied to the signal processing unit 9, and the signal processing unit 9 generates, for example, a tracking error by the DPD method and a focusing error signal by the astigmatism method. The generated tracking error and focusing error signals are supplied to the driver control unit 6 via the control unit 13.

  The driver control unit 6 transmits a tracking error signal to the driver 5. The driver 5 performs tracking by a tracking driver, for example, by a tracking coil of a biaxial actuator (not shown) of the optical pickup unit 4.

  Further, the driver control unit 6 transmits a focus error signal to the driver 5. The driver 5 performs focusing by a focus driver, for example, with a focus coil of a biaxial actuator (not shown) of the optical pickup unit 4.

  As a result, the objective lens 18 can always be kept at an appropriate position, and reproduction accuracy can be ensured.

  Also, the RF-LNC 41 subtracts the signal of the FPD 24 from the signal of the SUM 39 to remove noise in the signal of the SUM 39, and generates an RF signal. Thereafter, the RF signal is supplied to the signal processing unit 9.

  For example, under the control of the control unit 13, the signal processing unit 9 demodulates the supplied noise-cancelled RF signal and performs processing such as error detection and correction to generate a signal such as music information and the like to the D / A converter 10. Supply.

  Further, the D / A converter 10 converts a signal such as music information supplied into an analog signal under the control of the control unit 13, for example, and supplies the analog signal to the input / output unit 11.

  The input / output unit 11 outputs, for example, the supplied acoustic information as voice or the like through a speaker or the like of the acoustic unit (not shown) under the control of the control unit 13, and the music information recorded on the optical disc 2 is reproduced. It becomes.

  This is the end of the description of the operation of the optical disc recording / reproducing apparatus 1.

  As described above, according to the present embodiment, the optical disc recording / reproducing apparatus 1 has the four LNCs 38 in which the optical pickup unit 4 subtracts the signals of the FPD 24 from the signals of the areas A to D of the four-divided PD 22 to remove noise. Therefore, the quality of the tracking error signal can be improved to improve the accuracy of the DPD method, that is, the tracking accuracy, and the noise of the FPD 24 signal is subtracted from the RF signal added by the SUM 39 to remove noise. Since the RF-LNC 41 is provided, the noise component in the RF signal can be removed in phase with the signal of the FPD 24.

  The optical disc recording / reproducing apparatus 1 has an RF-LNC 41 for removing noise of the RF signal and four LNCs 38 used for generating tracking and focusing error signals, so that the accuracy is high. One RF-LNC 41 for obtaining an RF signal can be provided.

  Further, since the FPD 24 and the four-divided PD 22 are mounted on the same substrate 21, process variations can be suppressed, and only a circuit design error becomes a problem, thereby enabling stable broadband laser noise cancellation.

  Further, by mounting the FPD 24 and the four-divided PD 22 on the same substrate 21, process variations are suppressed, and the FPD 24 signal, the signals of the regions A to D of the four-divided PD 22, and the RF signal are transmitted on the same PDIC 23. The group delay characteristics of each signal received by each element are designed to be substantially the same. Thereby, since the influence by the difference in group delay characteristic can be suppressed, a noise component can be removed more correctly.

  Further, the FPD 24 and the 4-divided PD 22 are mounted on the same substrate 21, and the group delay error between the RF signal and the FPD signal is 0.5 ns or less, and the area A to D signal of the 4-divided PD is between the D signal and the FPD signal. The group delay error is set to 1 ns or less. Therefore, the necessary LNC effect amount can be ensured. In addition, reproduction jitter can be reduced and the system margin can be expanded. For this reason, the assembly precision and processing precision of components can be eased.

  Next, an optical disk recording / reproducing apparatus using the optical pickup according to the second embodiment of the present invention will be described. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, the description thereof is omitted, and different portions will be described.

  FIG. 6 is a schematic diagram showing the PDIC 23 of the optical pickup according to the second embodiment of the present invention.

  In the present embodiment, an arithmetic circuit (hereinafter referred to as “SUM”) 39 that adds four signals respectively divided from the outputs of the four LNCs 38 is included, and the RF-LNC 41 of the first embodiment. Does not have. The four LNCs 38 are connected not only to the SUM 39 but also to the signal processing unit 9. Further, the four LNCs 38 are set to have the same performance as the RF-LNC 41 of the first embodiment.

  Next, the operation of the optical disc recording / reproducing apparatus configured as described above will be described. It should be noted that until the signal is amplified by the I / V amplifier 37 and after the signal is supplied to the signal processing unit 9, since it is the same as in the first embodiment, from the signal amplification to the supply of the signal processing unit 9 explain.

  The control unit 13 causes each LNC 38 to subtract the signal of the FPD 24 from the signal output in each of the areas A to D of the 4-divided PD 22 and amplified by each I / V amplifier 37, and outputs the signal after noise cancellation. The four signals whose noise has been canceled are supplied to the signal processing unit 9, respectively. On the other hand, the control unit 13 causes the SUM 39 to add the four output signals whose noise has been canceled by each LNC 38 to output an RF signal. The RF signal is also supplied to the signal processing unit 9.

  As described above, according to the present embodiment, the optical disc recording / reproducing apparatus 1 has the four LNCs 38 in which the optical pickup unit 4 subtracts the signals of the FPD 24 from the signals of the areas A to D of the four-divided PD 22 to remove noise. Therefore, it is possible to improve the quality of the tracking error signal and improve the accuracy of the DPD method, that is, the accuracy of tracking, and add the four signals each divided from the outputs of the four LNCs 38. Therefore, the noise component in the RF signal can also be removed in phase with the signal of the FPD 24.

  Further, since the SUM 39 for adding the four signals respectively divided from the outputs of the four LNCs 38 is provided, the RF-LNC 41 of the first embodiment is not necessary, and the PDIC 23 can be reduced in size, for example. it can.

  The present invention is not limited to any of the above-described embodiments, and can be implemented with appropriate modifications within the scope of the technical idea of the present invention.

  For example, in the above-described embodiment, the case of reproducing the optical disc 2 has been mainly described. However, the present invention is not limited to this, and other recording media may be used as long as recording and reproduction are performed using laser light. As a result, further customization can be achieved.

1 is a block diagram of an optical disc recording / reproducing apparatus according to a first embodiment of the present invention. 1 is a schematic explanatory diagram of an optical pickup according to a first embodiment of the present invention. It is a schematic diagram of PDIC of the optical pick-up of 1st Embodiment. It is arrangement | positioning explanatory drawing of each PD and FPD of the optical pick-up of 1st Embodiment. It is a graph which shows the group delay (error) characteristic of a LNC effect amount and a frequency. It is a schematic diagram of PDIC of the optical pick-up of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk recording / reproducing apparatus 2 Optical disk 3 Spindle motor 4 Optical pick-up part 5 Driver 6 Driver control part 7 Amplifier 8 Noise cancellation circuit 9 Signal processing part 10 D / A converter 11 Input / output part 12 Recording control circuit 13 Control part 14 Semiconductor laser element 15 Grating 16 Beam Splitter 17 Collimator Lens 18 Objective Lens 19 Mirror 20 Detection Lens 21 Substrate 22 4 Division PD
23 PDIC
24 FPD
34 Optical pickup A, B, C, D area 37 I / V amplifier 38 LNC
39 SUM
41 RF-LNC

Claims (8)

A light source for irradiating an optical disc with laser light;
A first light receiving element divided into a plurality of regions for receiving the reflected light of the laser light from the optical disc;
A second light receiving element disposed in the vicinity of the first light receiving element and directly receiving the laser light from the light source;
First computing means for subtracting the signal of the second light receiving element from the respective signals generated in each region of the first light receiving element;
Second computing means for adding signals respectively shunted from the respective signals generated in the respective regions of the first light receiving element;
An optical pickup comprising: third arithmetic means for subtracting the signal of the second light receiving element from the signal generated by addition by the second arithmetic means. The optical pickup according to claim 1,
An optical pickup characterized in that the first light receiving element and the second light receiving element are disposed on the same chip. The optical pickup according to claim 1,
The signal from the second light receiving element, each signal generated in each area of the first light receiving element, and each signal generated in each area of the first light receiving element are added by the second arithmetic means. An optical pickup characterized in that the delay characteristics of the generated signals are the same. The optical pickup according to claim 1,
A delay error between a signal generated in each region of the first light receiving element and added by the second calculation means and a signal from the second light receiving element is 0.5 ns or less, An optical pickup characterized in that a delay error between each signal generated in each region of one light receiving element and a signal from the second light receiving element is 1 ns or less. A light source for irradiating an optical disc with laser light;
A first light receiving element divided into a plurality of regions for receiving the reflected light of the laser light from the optical disc;
A second light receiving element disposed in the vicinity of the first light receiving element and directly receiving the laser light from the light source;
First computing means for subtracting the signal of the second light receiving element from the respective signals generated in each region of the first light receiving element;
Second computing means for adding signals respectively shunted from the respective signals generated in the respective regions of the first light receiving element;
An optical disc recording / reproducing apparatus comprising: an optical pickup comprising: third arithmetic means for subtracting the signal of the second light receiving element from the signal generated by addition by the second arithmetic means. The optical disc recording / reproducing apparatus according to claim 5 ,
In the optical pickup, the first optical receiving element and the second optical receiving element are arranged on the same chip. The optical disc recording / reproducing apparatus according to claim 5 ,
The optical pickup includes a signal from the second light receiving element, each signal generated in each area of the first light receiving element, and the second calculation generated in each area of the first light receiving element. An optical disk recording / reproducing apparatus characterized in that the delay characteristics of the signals generated by addition by the means are the same. The optical disc recording / reproducing apparatus according to claim 5 ,
A delay error between a signal generated in each region of the first light receiving element of the optical pickup and added by the second calculation means and a signal from the second light receiving element is 0.5 ns. An optical disc recording / reproducing apparatus, wherein a delay error between each signal generated in each region of the first light receiving element and a signal from the second light receiving element is 1 ns or less.

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