JP2009187633A - Optical disk device and optical beam radiation angle adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately irradiate a tilted optical disk with an optical beam. <P>SOLUTION: The optical disk device 10 generates radius information MR1 and MR2 based on first address information MA1 showing an address followed by the focus Fr1 of a red optical beam Lr1on on a servo layer 104 and second address information MA2 showing an address followed by the focus Fr2 of a red optical beam Lr2 on a servo layer 105, while an objective lens 6 is focus-controlled and tracking-controlled to focus the read optical beam Lr1 on a target track TG1; and tilts the optical axis XL of the read optical beams Lr1 and Lr2 and a blue optical beam LB1 to be aligned with a normal XG of the servo layer 104 on the target track TG1 by tilting the objective lens 6 according to a tilt angle θG calculated by using the address information and an expression (6). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus and a light beam irradiation angle adjusting method, and is suitable for application to an optical disc apparatus that records or reproduces information by irradiating an optical disc with a light beam, for example.

  2. Description of the Related Art Conventionally, in an optical disc apparatus, a light beam is irradiated onto an optical disc, such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and a Blu-ray Disc (registered trademark, hereinafter referred to as BD), and its reflection A device that reproduces information by reading light is widely used.

  In such an optical disc apparatus, information is recorded by irradiating the optical disc with a light beam and changing the local reflectance of the optical disc.

  In this optical disc, the size of the beam spot formed when the light beam is collected by an objective lens or the like is given by approximately λ / NA (λ: wavelength of the light beam, NA: numerical aperture), and the resolution is also this It is known to be proportional to the value. For example, in the BD system, data of approximately 25 [GB] can be recorded on an optical disk having a diameter of 120 [mm].

  By the way, various kinds of information such as various contents such as music contents and video contents, or various data for computers are recorded on the optical disc. In particular, in recent years, the amount of information has increased due to higher definition of video and higher sound quality of music, and there has been a demand for an increase in the number of contents recorded on one optical disc. It is desired.

Therefore, some optical disk devices have been proposed which, for example, use a hologram to perform standing wave recording in a uniform recording layer of the optical disk, and to increase the capacity of the optical disk by multilayering it. (For example, refer to Patent Document 1).
JP 2007-220206 A (FIG. 24)

  By the way, in the optical disc corresponding to the optical disc apparatus having such a configuration, since the inside of the recording layer is uniform, a servo layer for positioning on which a track or the like is formed is separately provided, and the servo layer is used in the recording layer. The recording position is specified. Further, a method for forming a recording mark representing information is not limited to a hologram, and for example, it is conceivable to form a minute cavity in the recording layer.

  As shown in FIG. 1, when recording information, the optical disc apparatus 1 transmits a predetermined servo light beam Lr through a beam splitter 5 and condenses it on a servo layer 2 </ b> A of the optical disc 2 through an objective lens 6.

  The optical disc apparatus 1 detects a reflected light beam formed by reflecting the servo light beam Lr on the servo layer 2A of the optical disc 2, and performs servo control by performing focus control and tracking control of the objective lens 6 according to the detection result. The light beam Lr is focused on the target track TG of the servo layer 2A.

  In this state, the optical disc apparatus 1 reflects the information light beam Lb by the beam splitter 5 and focuses it on the target position PG in the recording layer 2B of the optical disc 2 via the position-controlled objective lens 6.

  As a result, the optical disc apparatus 1 can locally increase the temperature of the recording layer 2B by the information light beam Lb at the target position PG in the recording layer 2B of the optical disc 2, and the recording mark that is hollow at the target position PG. An RM can be formed.

  That is, in the optical disc 2, as shown in FIG. 2A, the target position PG in the recording layer 2B is a predetermined distance d from the target track TG in the normal direction of the servo layer 2A (and the surface of the optical disc 2, etc.). It becomes the moved position.

  In this case, the optical disc apparatus 1 makes the optical axes XL of the servo light beam Lr and the information light beam Lb coincide with each other, and makes the optical axis vertically incident on the servo layer 2A (that is, coincides with the normal line XD). Therefore, the focal point Fb can be positioned directly below the target track TG and can be adjusted to the target position PG.

  Incidentally, when reproducing information, the optical disc apparatus 1 uses only the servo light beam Lr and the information light beam Lb, irradiates the information light beam Lb to the target position PG, and reads the reflected light.

  However, the optical disk device 1 can cause the servo light beam Lr to enter the servo layer 2A perpendicularly, as shown in FIG. 2B, due to factors such as the warp of the optical disk 2 itself and the inclination of the optical disk 2 with respect to the optical disk device 1. There may not be.

  Here, if the angle formed between the normal XD of the servo layer 2A and the optical axis XL of the servo light beam Lr is θ [°], the optical disc apparatus 1 shifts the focal point Fb of the information light beam Lb from the correct target position PG. E = d × sin θ.

  According to the standard, the track pitch in the DVD system is about 0.74 [μm], and the track pitch in the BD system is about 0.32 [μm]. Here, for example, when the distance d = 400 [μm] and the inclination angle θ = 0.1 [°], the deviation amount E between the focal point F2 and the target position PG is d × sin θ≈0.7 [μm], This corresponds to one track of the DVD system or two tracks of the BD system.

  Therefore, the optical disc apparatus 1 may erroneously read information on different tracks when reproducing the information. Further, when the information is recorded, the optical disc apparatus 1 may record the information on the wrong track, and may overwrite the existing information (that is, erroneously erase).

  As described above, the optical disc apparatus 1 has a problem that when the optical disc 2 is tilted, there is a risk that information recording accuracy and reproduction accuracy may be significantly lowered.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an optical disk apparatus and a light beam irradiation angle adjusting method capable of appropriately irradiating a light beam when the optical disk is tilted.

  In order to solve this problem, in the optical disc apparatus of the present invention, the first light beam and the second light beam for determining the irradiation position of the information light beam for recording information on the recording layer of the optical disc or reproducing the information from the recording layer. A light beam adjusting unit that adjusts a convergent and divergent state of the light beam, and condensing the first light beam, the second light beam, and the information light beam, respectively, thereby focusing the first light beam and the second light beam. The first reflected light beam is detected by reflecting the first light beam by the objective lens that separates the focal point by a predetermined distance and the first servo layer in which the position information for specifying the position in the recording layer of the optical disk is recorded. First position information for acquiring first position information representing a focal position of the first light beam in the first servo layer based on the first detection unit that performs the detection and the detection result of the first reflected light beam. A second reflected light beam formed by the obtaining unit and the second reflected light beam is transmitted through the first servo layer and is reflected by the second servo layer that is separated from the first servo layer by a predetermined distance and has position information recorded thereon. A second position information acquiring unit that acquires second position information representing a focal position of the second light beam in the second servo layer based on a detection result of the second reflected light beam; a first position; A calculating unit that calculates an inclination angle of the optical disk based on the information and the second position information and the interval between the first servo layer and the second servo layer, a first light beam and a second light beam for the optical disk according to the inclination angle, and An inclination control unit is provided for controlling the irradiation angle of the information light beam to be inclined toward the inner or outer peripheral side of the optical disc.

  Thereby, the tilt angle of the optical disk can be calculated using the first position information and the second position information read from the first servo layer and the second servo layer, respectively, and the irradiation angle of the light beam is adjusted according to the tilt angle. be able to.

  In the light beam irradiation angle adjusting method of the present invention, the first light beam and the second light for determining the irradiation position of the information light beam for recording information on the recording layer of the optical disc or reproducing the information from the recording layer. The convergence / divergence state of the beam is adjusted, the first light beam, the second light beam, and the information light beam are incident on a predetermined objective lens, and the focal point of the first light beam and the focal point of the second light beam are set at a predetermined interval. A first reflected light beam formed by reflecting the first light beam by a first servo layer on which a light beam condensing step for separating the first light beam and position information for specifying a position in the recording layer of the optical disk is recorded. 1 detection step and a first position information acquisition step of acquiring first position information representing a focal position of the first light beam in the first servo layer based on the detection result of the first reflected light beam Second detection for detecting a second reflected light beam transmitted through the first servo layer and reflected by the second servo layer having position information separated from the first servo layer by a predetermined interval. A second position information acquisition step for acquiring second position information representing a focal position of the second light beam in the second servo layer based on the detection result of the second reflected light beam, the first position information, 2. A calculation step for calculating the tilt angle of the optical disc based on the position information and the interval between the first servo layer and the second servo layer, and the first light beam, the second light beam, and the information light beam for the optical disc according to the tilt angle. And an inclination control step for controlling the irradiation angle to be inclined toward the inner circumference side or the outer circumference side of the optical disc.

  Thereby, the tilt angle of the optical disk can be calculated using the first position information and the second position information read from the first servo layer and the second servo layer, respectively, and the irradiation angle of the light beam is adjusted according to the tilt angle. be able to.

  According to the present invention, the tilt angle of the optical disc can be calculated using the first position information and the second position information read from the first servo layer and the second servo layer, respectively, and the irradiation angle of the light beam according to the tilt angle. Thus, it is possible to realize an optical disc apparatus and a light beam irradiation angle adjustment method that can appropriately irradiate a light beam when the optical disc is tilted.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of Optical Disc First, the optical disc 100 used as an information recording medium in the present embodiment will be described. As shown in the external view of FIG. 3, the optical disc 100 as a whole is configured in a disk shape having a diameter of about 120 [mm], like a conventional CD, DVD, and BD, and a hole 100H is formed in the central portion. ing.

  Further, as shown in the cross-sectional view of FIG. 4, the optical disc 100 has a recording layer 101 for recording information in the center, and is configured so that the recording layer 101 is sandwiched from both sides by the substrates 102 and 103. Yes.

  The recording layer 101 is made of a resin material that generates bubbles when heated to a predetermined temperature or higher, and has a refractive index of about 1.6 at a wavelength of about 405 [nm], for example.

  When the blue light beam Lb1 having a wavelength of about 405 [nm] and having a relatively strong light intensity is condensed in the recording layer 101, the recording layer 101 generates bubbles at the position of the focal point Fb in the recording layer 101, The bubbles are maintained as recording marks RM by being naturally cooled or the like.

  When the recording mark RM is irradiated with the blue light beam Lb1 having a relatively weak light intensity, the recording mark RM reflects the blue light beam Lb1 due to a difference in refractive index at the boundary surface between the internal cavity and the surrounding resin material. It is assumed that the blue reflected light beam Lb2.

  Incidentally, the recording layer 101 does not reflect the blue light beam Lb1 because the refractive index is uniform even when the blue light beam Lb1 is irradiated to a portion where the recording mark RM is not formed.

  The substrates 102 and 103 are made of a material such as polycarbonate or glass, for example, and have a refractive index substantially equal to that of the recording layer 101 with respect to a light beam having a wavelength of 405 [nm] and a wavelength of 660 [nm]. Is incident on the opposite surface with high transmittance. Further, the substrates 102 and 103 have a certain degree of strength and play a role of protecting the recording layer 101.

  The optical disc 100 also has a servo layer 104 on the boundary surface between the recording layer 101 and the substrate 102. The servo layer 104 is made of a dielectric multilayer film or the like, and transmits the blue light beam Lb1 and the blue reflected light beam Lb2 having a wavelength of 405 [nm] and about 50% of the red light beam having a wavelength of 660 [nm]. It has a wavelength selectivity that reflects at a ratio and transmits the remaining 50%.

  Further, the optical disc 100 has a servo layer 105 at the boundary surface between the recording layer 101 and the substrate 103. The servo layer 105 is formed of a dielectric multilayer film or the like, similar to the servo layer 104, and transmits a blue light beam Lb1 having a wavelength of 405 [nm] and reflects a red light beam having a wavelength of 660 [nm]. Selectivity.

  The servo layers 104 and 105 form guide grooves used for tracking servo and focus servo. Specifically, the servo layers 104 and 105 are spirally formed by lands and grooves similar to a general BD-R (Recordable) disk. Forming a track. In this track, an address consisting of a series of numbers for each predetermined recording unit is recorded, and a track on which information is recorded or reproduced can be specified by the address.

  Further, the servo layers 104 and 105 are assigned the same address at locations corresponding to each other with respect to the direction along the rotation center axis of the optical disc 100 (that is, the thickness direction). Therefore, a straight line connecting the same addresses in the servo layers 104 and 105 is a normal line of the servo layers 104 and 105.

  When the servo layer 104 is irradiated with a red light beam Lr1 having a wavelength of about 660 [nm] from the substrate 102 side, the servo layer 104 reflects the red light beam Lr1 at a rate of about 50%. Hereinafter, the light beam reflected at this time is referred to as a red reflected light beam Lr3.

  For example, in the optical disc apparatus, the red reflected light beam Lr3 matches the focus Fr1 of the red light beam Lr1 collected by the objective lens 6 with a target track of the servo layer 104 (hereinafter referred to as a target track TG1). Therefore, it is assumed that the objective lens 6 is used for position control (that is, focus control and tracking control).

  The servo layer 104 transmits the red light beam Lr2 having a wavelength of about 660 [nm] from the substrate 102 side at a rate of about 50%. At this time, the red light beam Lr2 passes through the recording layer 101 and is irradiated onto the servo layer 105.

  The servo layer 105 reflects the red light beam Lr2. Hereinafter, the light beam reflected at this time is referred to as a red reflected light beam Lr4. The red reflected light beam Lr4 passes through the recording layer 101, passes through the servo layer 104 at a rate of about 50%, and then enters the objective lens 6.

  For example, in the optical disc apparatus, the red reflected light beam Lr4 is a target track of the servo layer 105, that is, a track at a position corresponding to the target track TG1 with respect to the normal direction of the servo layer 104 (hereinafter referred to as target track TG2). Is used for the purpose of detecting the amount of deviation of the red light beam Lr2 from the focal point Fr2 (details will be described later).

  In the following, the surface on the substrate 102 side of the optical disc 100 is referred to as a first surface 100A, and the surface on the substrate 103 side of the optical disc 100 is referred to as a second surface 100B. Further, the distance from the recording reflective film 104 in the recording layer 101 is referred to as a depth d.

  Actually, when information is recorded on the optical disk 100, the red light beam Lr1 is condensed by the position-controlled objective lens 6 and focused on the target track TG1 of the servo layer 104.

  Further, the blue light beam Lb1 that shares the optical axis XL with the red light beam Lr1 and is condensed by the objective lens 6 passes through the substrate 102 and the servo layer 104, and is behind the target track in the recording layer 101 (that is, the substrate). 103 side) is focused on a position having a depth d (hereinafter referred to as a target position PG). As a result, a recording mark RM is formed at the target position PG.

  Further, the optical disk 100 is moved from the servo layer 104 by a certain distance (that is, depth d) by moving the objective lens 6 or the optical disk 100 itself while maintaining the depth d of the focal point Fb1, or by rotating the optical disk 100 or the like. The recording marks RM are arranged in a plane at the locations. Hereinafter, the layer of the recording mark RM formed in this way is referred to as a mark layer.

  Further, the optical disc 100 is designed such that the thickness t1 of the recording layer 101 is sufficiently larger than the height of the recording mark RM (that is, the size in the thickness direction of the optical disc 100) RMh. For this reason, the optical disc 100 is recorded with the recording mark RM while the depth d of the focal point Fb is switched, so that a plurality of mark layers are stacked in the thickness direction of the optical disc 100 (also referred to as volume recording). Has been made to be able to do.

  For example, in the optical disc 100, when the thickness of the recording layer 101 is about 0.3 [mm], the distance between the mark layers is set to about 15 [μm] in consideration of the mutual interference between the recording marks RM. For example, about 20 mark layers can be formed in the recording layer 101. The distance between the mark layers may be various other values in consideration of the mutual interference between the recording marks RM.

  On the other hand, when the information is reproduced, the optical disc 100 is focused so that the red light beam Lr1 collected by the objective lens 6 is focused on the target track TG1 of the servo layer 104 in the same manner as when the information is recorded. The position of the objective lens 6 is adjusted.

  Further, in the optical disc 100, the focal point Fb of the blue light beam Lb1 that has passed through the substrate 102 and the servo layer 104 via the same objective lens 6 is focused on the target position PG in the recording layer 101. At this time, if the recording mark RM is recorded at the target position PG, the blue light beam Lb1 is reflected and becomes the blue reflected light beam Lb2.

  As described above, the optical disc 100 uses the red light beam Lr1 for servo (for position control) and the blue light beam Lb1 adjusted to the light intensity for information recording when information is recorded. A recording mark RM is formed as the information at the position of the focal point Fb, that is, on the back side of the target track TG1 in the servo layer 104 and at the target position PG having the target depth d.

  In addition, when recorded information is reproduced, the optical disc 100 uses a red light beam Lr1 for servo (for position control) and a blue light beam Lb1 adjusted to the light intensity for information reproduction, so that the focus Fb1 The blue reflected light beam Lb2 is generated from the recording mark RM recorded at the target position PG, that is, at the target position PG.

  Incidentally, in the optical disc 100, for example, when the code when the information is binary-coded is the value “1”, the recording mark RM is formed at the target position PG in the recording layer 101 of the optical disc 100, and the code has the value “0”. Sometimes, it is assumed that the recording mark RM is not formed at the target position PG. As a result, the optical disc 100 can represent the code value “1” or “0” at the target position PG depending on the presence or absence of the recording mark RM. As a result, the information can be binarized and held in the recording layer 101. .

(2) Configuration of Optical Disc Device In FIG. 5, the optical disc device 10 is configured with a control unit 11 as a center, and records information on, for example, a BD type optical disc 100 and reproduces information from the optical disc 100. Has been made to get.

  The control unit 11 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) in which various programs are stored, and a RAM (Random Access Memory) used as a work memory of the CPU. The optical disk device 10 is controlled in an integrated manner.

  When the optical disc 100 is loaded, the control unit 11 rotates the spindle motor 15 via the drive control unit 12 to rotate the optical disc 100 placed on a turntable (not shown) at a desired speed. Further, the control unit 11 drives the sled motor 16 via the drive control unit 12, thereby tracking the optical pickup 17 toward the inner peripheral side or the outer peripheral side of the optical disc 100 along the movement axes G 1 and G 2. Move to a large distance.

  The optical pickup 17 irradiates the optical disk 100 with a light beam and detects the reflected light beam based on the control of the control unit 11.

  For example, when the control unit 11 receives a reproduction command for reproducing information recorded on the optical disc 100 from an external device (not shown), the control unit 11 sends a predetermined reproduction control signal to the optical pickup 17 via the drive control unit 12. Supply.

  The optical pickup 17 collects the red light beam Lr1 by the objective lens 8 and irradiates the servo layer 104 of the optical disc 100, and also detects the red reflected light beam Lr3 that is the reflected light to generate a detection signal. The signal is supplied to the signal processing unit 13.

  Based on the detection signal, the signal processing unit 13 includes a focus error signal that represents a shift amount between the servo layer 104 of the optical disc 100 and the focus Fr1 of the red light beam Lr1 in the focus direction, the target track TG1 of the servo layer 104, and the A tracking error signal representing a deviation amount with respect to the tracking direction with respect to the focal point Fr1 is generated and supplied to the control unit 11 and the drive control unit 12.

  The drive control unit 12 generates a drive signal based on the focus error signal and the tracking error signal, and supplies this to the actuator 19. The actuator 19 drives the objective lens 6 in the focus direction and the tracking direction according to the drive signal.

  Incidentally, the actuator 19 can drive the objective lens 6 in the focus direction and the tracking direction, and can tilt the objective lens 6 toward the outer peripheral side or the inner peripheral side of the optical disc 100.

  Thus, the drive control unit 12 adjusts the focus Fr1 of the red light beam Lr1 to the target track TG1 and causes it to follow by performing focus control and tracking control of the objective lens 6.

  The optical pickup 17 condenses the blue light beam Lb1 by the objective lens 6, and detects the blue reflected light beam Lb2 formed by reflecting the blue light beam Lb1 by the recording mark RM (FIG. 4) in the recording layer 101. Then, a detection signal is generated and supplied to the signal processing unit 13.

  The signal processing unit 13 reproduces information by performing signal processing such as demodulation processing and decoding processing on the supplied detection signal, and supplies the information to the control unit 11. The control unit 11 sends this information to the external device that has supplied the playback command.

  On the other hand, when receiving a recording command for recording information on the optical disc 100 from an external device (not shown), the control unit 11 supplies information to be recorded to the signal processing unit 13. The signal processing unit 13 generates a recording signal by modulating information to be recorded, and supplies the recording signal to the optical pickup 17.

  The optical pickup 17 performs focus control and tracking control of the objective lens 6 as in the case of reproducing information from the optical disc 100, and then modulates the blue light beam Lb1 having a relatively strong light intensity based on the recording signal. However, the recording marks RM are sequentially formed in the recording layer 101 by irradiating the optical disc 100.

  As described above, the optical disc apparatus 10 performs focus control and tracking control of the objective lens 6 in the optical pickup 17 using the red light beam Lr1, and then irradiates the optical disc 100 with the blue light beam Lb1, thereby the optical disc 100. The information can be recorded on the optical disc 100, and the information can be reproduced from the optical disc 100.

(3) Configuration of Optical Pickup Next, the configuration of the optical pickup 17 will be described. As schematically shown in FIG. 6, the optical pickup 17 is roughly composed of a servo optical system 30 related to control of the objective lens 6 and an information optical system 50 related to information recording and reproduction.

(3-1) Configuration of Servo Optical System The servo optical system 30 irradiates the first surface 100A of the optical disc 100 with the red light beam Lr1, and the red light beam is reflected by the red light beam Lr1. The light beam Lr3 is received.

  In FIG. 8, the laser diode 31 of the servo optical system 30 can emit red laser light having a wavelength of about 660 [nm]. Actually, the laser diode 31 emits a predetermined amount of red light beam Lr0, which is a divergent light, based on the control of the control unit 11 (FIG. 5) and makes it incident on the collimator lens 32. The collimator lens 32 converts the red light beam Lr0 from diverging light into parallel light and makes it incident on the hologram plate 33.

  The hologram plate 33 has a hologram formed on a plate-shaped member having a high light transmittance. By diffracting the red light beam Lr0, the red light beams Lr1 having the same optical axes and different divergence angles. And Lr 2 are generated and made incident on the beam splitter 34.

  The beam splitter 34 transmits the red light beams Lr1 and Lr2 at a ratio of about 50% on the reflection / transmission surface 34S, and enters the dichroic prism 36.

  The reflection / transmission surface 36S of the dichroic prism 36 has so-called wavelength selectivity in which the transmittance and reflectance differ depending on the wavelength of the light beam, and a red light beam having a wavelength of about 660 [nm] is approximately 100%. It transmits light and reflects a blue light beam having a wavelength of about 405 [nm] at a rate of almost 100%.

  Actually, the dichroic prism 36 transmits the red light beams Lr1 and Lr2 through the reflection / transmission surface 36S, and makes them enter the objective lens 6.

  The objective lens 6 collects the red light beam Lr1 and irradiates it toward the first surface 100A of the optical disc 100. At this time, as shown in FIG. 4, the red light beam Lr1 is transmitted through the substrate 102, reflected by the servo layer 104, and becomes a red reflected light beam Lr3 directed in the opposite direction to the red light beam Lr1.

  Thereafter, the red reflected light beam Lr3 sequentially passes through the objective lens 6 and the dichroic prism 36 and then enters the beam splitter 34. The beam splitter 34 reflects the red reflected light beam Lr3 at a ratio of about 50% by the reflection / transmission plate 34S and makes it incident on the condenser lens 40.

  The condensing lens 40 converges the red reflected light beam Lr3, causes the lens 41 to provide astigmatism, and enters the beam splitter 42. The beam splitter 42 includes a reflection / transmission plate 42S having a transmittance of about 50%. The red reflected light beam Lr3 is reflected by the reflection / transmission surface 42S at a ratio of about 50% and is applied to the photodetector 43.

  By the way, in the servo optical system 30, the focused state when the red light beam Lr1 is condensed by the objective lens 6 and applied to the servo layer 104 of the optical disc 100 is focused by the condensing lens 41, and the red reflected light beam Lr3 is condensed. The optical positions of various optical components are adjusted so as to be reflected in the in-focus state when the photo-detector 43 is irradiated.

  As shown in FIG. 7A, the photodetector 43 has four detection areas 43A, 43B, 43C, and 43D that are divided in a lattice pattern on the surface irradiated with the red reflected light beam Lr3. Incidentally, the direction (vertical direction in the figure) indicated by the arrow a1 corresponds to the traveling direction of the track when the red light beam Lr1 is applied to the servo layer 104 (FIG. 3).

  The photodetector 43 detects a part of the red reflected light beam Lr3 by the detection areas 43A, 43B, 43C, and 43D, respectively, and detects detection signals U1A, U1B, U1C, and U1D (hereinafter, these are summarized) according to the amount of light detected at this time. Are called U1A to U1D) and sent to the signal processing unit 13 (FIG. 5).

  Here, the optical pickup 17 performs focus control on the objective lens 6 by a so-called astigmatism method.

  That is, the signal processing unit 13 calculates the focus error signal SFE1 based on the detection signals U1A to U1D according to the following expression (1) by the first focus error signal generation unit 71A shown in FIG. 12 focus drive signal generators 78A.

  The focus error signal SFE1 represents the amount of deviation in the focus direction between the focal point Fr1 of the red light beam Lr1 and the servo layer 104 of the optical disc 100.

  The drive control unit 12 generates a focus drive signal SFD1 based on the focus error signal SFE1 by the focus drive signal generation unit 78A, and supplies it to the actuator 19 (FIG. 6). The actuator 19 drives the objective lens 6 in the focus direction according to the focus drive signal SFD1.

  Thus, the optical pickup 17 performs feedback control (that is, focus control) on the objective lens 6 so that the red light beam Lr1 is focused on the servo layer 104 of the optical disc 100.

  The optical pickup 17 performs tracking control by the so-called push-pull method for the objective lens 6 (FIG. 6).

  That is, the signal processing unit 13 calculates the tracking error signal STE1 based on the detection signals U1A to U1D according to the following equation (2) by the first tracking error signal generation unit 71B (FIG. 8), and uses this as the drive control unit. 12 tracking drive signal generators 78B.

  The tracking error signal STE1 represents the amount of deviation between the focal point Fr1 of the red light beam Lr1 and the target track TG1 in the servo layer 104 of the optical disc 100.

  The drive control unit 12 generates a tracking drive signal STD1 based on the tracking error signal STE1 by the tracking drive signal generation unit 78B, and supplies this to the actuator 19 (FIG. 6). The actuator 19 drives the objective lens 6 in the tracking direction according to the tracking drive signal STD1.

  Further, the signal processing unit 13 calculates the first servo RF signal SRF1 by the first servo RF signal generation unit 71C (FIG. 8) based on the detection signals U1A to U1D according to the following equation (3), 1 address information acquisition unit 72C.

  The first address information acquisition unit 72C generates first address information MA1 by performing predetermined demodulation processing and decoding processing on the first servo RF signal SRF1, and generates the first address information MA1 and the first radius information acquisition unit 73C and the drive Supply to the control unit 12. The first address information MA1 represents the address of the track on which the red light beam Lr1 is condensed in the servo layer 104.

  The tracking drive signal generator 78B of the drive controller 12 determines whether or not the focal point Fr1 of the red light beam Lr1 is positioned on the correct target track TG1 based on the first address information MA1. When the red light beam Lr1 is focused on an incorrect track other than the target track TG1, the tracking drive signal generation unit 78B is configured to track the red light beam Lr1 on a track basis so that the red light beam Lr1 is focused on the correct target track TG1. Perform tracking control.

  Thus, the optical disc apparatus 10 performs tracking control of the objective lens 6 so that the red light beam Lr1 is focused on the target track TG1 in the servo layer 104 of the optical disc 100.

  As described above, the optical disc apparatus 10 irradiates the servo layer 104 of the optical disc 100 with the red light beam Lr1 by the servo optical system 30 of the optical pickup 17, and the objective lens based on the light reception result of the red reflected light beam Lr3 that is the reflected light. 6 focus control and tracking control are performed, and the red light beam Lr1 is focused on the target track TG1 of the servo layer 104.

  On the other hand, the red light beam Lr2 incident on the objective lens 6 (FIG. 6) is condensed by the objective lens 6 and irradiated onto the optical disc 100. At this time, since the red light beam Lr2 is adjusted by the hologram plate 33 so that the divergence angle differs from the red light beam Lr1 by a predetermined amount, the servo layer 105 is transmitted through the servo layer 104 at a rate of about 50%. It is focused on.

  Here, in the optical pickup 17, the distance between the focal point Fr1 of the red light beam Lr1 and the focal point Fr2 of the red light beam Lr2 depends on the optical characteristics and arrangement of the hologram plate 33 and each optical component. It is adjusted so as to coincide with d101 (FIG. 4).

  Therefore, the optical pickup 17 focuses the red light beam Lr1 on the servo layer 104 of the optical disc 100 by the focus-controlled and tracking-controlled objective lens 6 and simultaneously focuses the red light beam Lr2 on the servo layer 105. Can do.

  The red light beam Lr2 is reflected by the servo layer 105 and becomes a red reflected light beam Lr4. The red reflected light beam Lr4 passes through the recording layer 101, passes through the servo layer 104 at a rate of about 50%, and then enters the objective lens 6 (FIG. 6).

  Thereafter, the red reflected light beam Lr4 enters the beam splitter 42 through an optical path substantially similar to that of the red reflected light beam Lr2. The beam splitter 42 transmits the red reflected light beam Lr4 at a rate of about 50% on the reflection / transmission surface 42S, and irradiates the photodetector 44 with it.

  As shown in FIG. 7B, the photodetector 44 has four detection regions 44A, 44B, 44C, and 44D that are divided in a lattice shape on the surface irradiated with the red reflected light beam Lr4. Incidentally, the direction (vertical direction in the figure) indicated by the arrow a2 corresponds to the traveling direction of the track when the red light beam Lr2 is applied to the servo layer 105 (FIG. 4).

  The photodetector 44 detects a part of the red reflected light beam Lr4 by the detection areas 44A, 44B, 44C, and 44D, respectively, and detects the detection signals U2A, U2B, U2C, and U2D (hereinafter, these are summarized) according to the detected light amount. And U2A to U2D) are respectively generated and sent to the signal processing unit 13 (FIG. 5).

  By the way, in the servo optical system 30, the focused state when the red light beam Lr2 is condensed by the objective lens 6 and applied to the servo layer 105 of the optical disc 100 is focused by the condensing lens 41, and the red reflected light beam Lr4 is condensed. The optical position and the like of the photo detector 44 are adjusted so as to be reflected in the focused state when the photo detector 44 is irradiated.

  At this time, a part of the red reflected light beam Lr3 is also irradiated to the photodetector 44 through the beam splitter 42 but is not focused (defocused). For this reason, the photodetector 44 can detect the red reflected light beam Lr4 by the detection regions 44A, 44B, 44C, and 44D without being substantially affected by the red reflected light beam Lr3.

  Incidentally, a part of the red reflected light beam Lr4 is also reflected by the beam splitter 42 and irradiated to the photodetector 43 described above, but it is still out of focus. For this reason, the photodetector 43 can detect the red reflected light beam Lr3 by the detection regions 43A, 43B, 43C, and 43D without being substantially affected by the red reflected light beam Lr4.

  The signal processing unit 13 calculates the tracking error signal STE2 based on the detection signals U2A to U2D according to the following equation (4) by the tracking error signal generation unit 21D (FIG. 8), and supplies this to the drive control unit 12. To do.

  This tracking error signal STE2 represents the amount of deviation between the focal point Fr2 of the red light beam Lr2 and the target track TG2 in the servo layer 105 of the optical disc 100.

  Further, the signal processing unit 13 uses the second servo RF signal generation unit 71E to calculate the second servo layer RF signal SRF2 based on the detection signals U2A to U2D according to the following equation (5).

  The signal processing unit 13 generates second address information MA2 by performing predetermined demodulation processing and decoding processing on the second servo RF signal SRF2, and supplies this to the second radius information acquisition unit 73E. The second address information MA2 represents the address of the track on which the red light beam Lr2 is condensed in the servo layer 105.

  As described above, the optical disk apparatus 10 detects the red reflected light beam Lr4 by the servo optical system 30 of the optical pickup 17, and based on the detection signals U2A to U2D as detection results, the focal point Fr2 of the red light beam Lr2 and the servo layer. A tracking error signal STE2 indicating the relationship with the target track TG2 at 105 and second address information MA2 are generated.

  The use of the tracking error signal STE2 and the second address information MA2 will be described later.

(3-2) Configuration of Information Optical System The information optical system 50 (FIG. 6) irradiates the first surface 100A of the optical disc 100 with the blue light beam Lb1 as the information light beam, and the optical disc 100 causes the blue light to be emitted. A blue reflected light beam Lb2 formed by reflecting the beam Lb1 is received.

  The laser diode 51 of the information optical system 50 can emit blue laser light having a wavelength of about 405 [nm]. In practice, the laser diode 51 emits a blue light beam Lb1 made of divergent light based on the control of the control unit 11 (FIG. 5) and makes it incident on the collimator lens 52. The collimator lens 52 converts the blue light beam Lb1 from diverging light into parallel light and makes it incident on the half-wave plate 53.

  At this time, the blue light beam Lb 0 is incident on the polarization beam splitter 54 after the polarization direction is rotated by a predetermined angle by the half-wave plate 53.

  The polarization beam splitter 54 is configured to reflect or transmit the light beam on the reflection / transmission surface 54S at a different rate depending on the polarization direction of the light beam. For example, the reflection / transmission surface 55S transmits a P-polarized light beam at a rate of approximately 100% and reflects the S-polarized light beam at a rate of approximately 100%.

  In practice, the polarization beam splitter 54 transmits the blue light beam Lb1 made of P-polarized light on the reflection / transmission surface 54S at a rate of approximately 100% and makes it incident on the quarter-wave plate 55.

  The quarter wavelength plate 55 is configured to mutually convert the light beam between linearly polarized light and circularly polarized light. For example, the quarter wavelength plate 55 converts the blue light beam Lb1 formed of P polarized light (that is, linearly polarized light) into left circularly polarized light. To enter the relay lens 56.

  The relay lens 56 converts the blue light beam Lb1 from parallel light into convergent light by the movable lens 57, converts the blue light beam Lb1 that has become divergent light after convergence into the converged light again by the fixed lens 58, and the dichroic prism 36. To enter.

  Here, the movable lens 57 is moved in the optical axis direction of the blue light beam Lb1 by the actuator 57A. In practice, the relay lens 56 can change the convergence state of the blue light beam Lb1 emitted from the fixed lens 58 by moving the movable lens 57 by the actuator 57A based on the control of the control unit 11 (FIG. 5). Has been made.

  The dichroic prism 36 reflects the blue light beam Lb1 by the reflection / transmission surface 36S according to the wavelength of the blue light beam Lb1, and makes it incident on the objective lens 6. Incidentally, when the blue light beam Lb1 is reflected by the reflection / transmission surface 36S, the polarization direction of the circularly polarized light is inverted, and is converted from, for example, left circularly polarized light to right circularly polarized light.

  That is, as shown in FIG. 9 corresponding to FIG. 6, the optical pickup 17 adjusts the convergence and divergence state of the red light beams Lr1 and Lr2 and the blue light beam Lb1 by various optical components constituting the light beam adjusting unit 60. These are made incident on the objective lens 6.

  The objective lens 6 (FIG. 6) collects the blue light beam Lb1 and irradiates the optical disc 100 with it. At this time, the blue light beam Lb1 passes through the substrate 102 and the servo layer 104 and is focused in the recording layer 101 as shown in FIG. Here, the position of the focal point Fb of the blue light beam Lb1 is determined by the convergence state when it is emitted from the fixed lens 58 of the relay lens 56.

  In practice, the optical disc apparatus 10 moves the movable lens 57 based on the control of the control unit 11, thereby setting the depth d of the focal point Fb according to the position of the movable lens 57 to the servo layer 104 side in the recording layer 101. Alternatively, it can be moved to the servo layer 105 side.

  For example, when the blue light beam Lb1 has a relatively strong recording light intensity, the recording mark RM is formed at the position of the focal point Fb in the recording layer 101.

  When the blue light beam Lb1 has a relatively weak light intensity for reproduction, if the recording mark RM is formed at the position of the focal point Fb, the blue light beam Lb1 is reflected by the recording mark RM and becomes the blue reflected light beam Lb2. . Incidentally, at this time, the polarization direction of the circularly polarized light beam Lb2 is reversed, and is converted from, for example, right circularly polarized light to left circularly polarized light.

  The blue reflected light beam Lb <b> 2 is converged to some extent by the objective lens 6, is then reflected by the reflection / transmission surface 36 </ b> S of the dichroic prism 36, and enters the relay lens 56. Incidentally, when the blue reflected light beam Lb2 is reflected by the reflection / transmission surface 36S, the polarization direction of the circularly polarized light is inverted, and is converted from, for example, left circularly polarized light to right circularly polarized light.

  Subsequently, the blue reflected light beam Lb2 is converted into parallel light by the fixed lens 58 and the movable lens 57 of the relay lens 56, and further converted from right circularly polarized light to S polarized light (linearly polarized light) by the quarter wavelength plate 55. Then, the light enters the polarization beam splitter 54.

  The polarization beam splitter 54 reflects the blue light beam Lb2 on the reflection / transmission surface 54S according to the polarization direction of the blue reflected light beam Lb2, and causes the light to enter the condenser lens 61. The condensing lens 61 condenses the blue reflected light beam Lb2 and irradiates the photodetector 62 with it.

  Incidentally, each optical component in the information optical system 50 is arranged so that the blue reflected light beam Lb2 is focused on the photodetector 62.

  As shown in FIG. 7C, the photodetector 62 detects the light intensity of the blue reflected light beam Lb2 by the detection region 62A, generates a detection signal U3 according to the detected light intensity, and performs signal processing on the detected signal U3. It supplies to the part 13 (FIG. 5).

  The detection signal U3 represents information recorded on the optical disc 100. Therefore, the signal processing unit 13 associates whether or not the blue reflected light beam Lb2 is detected with the value “1” or “0” based on the detection signal U3, and performs predetermined demodulation processing, decoding processing, and the like. Thus, reproduction information is generated, and this reproduction information is supplied to the control unit 11.

  As described above, the information optical system 50 condenses the blue light beam Lb1 in the recording layer 101 of the optical disc 100 via the objective lens 6 and records the recording mark RM at the target position PG which is the position of the focal point Fb when information is recorded. When the information is reproduced, the detection signal U3 corresponding to the presence or absence of the recording mark RM at the target position PG is generated.

  As a result, when reproducing information, the optical disc apparatus 10 receives the blue reflected light beam Lb2 when the recording mark RM is formed at the target position PG in the recording layer 101 of the optical disc 100, and the target position PG When the recording mark RM is not formed, the blue reflected light beam Lb2 is not received. Thereby, the optical disc apparatus 10 can recognize whether the information of the target position PG is the value “1” or “0”, and finally reproduces the information recorded on the recording layer 101 of the optical disc 100. be able to.

(3-3) Response to Optical Disk Tilt By the way, in the servo layers 104 and 105 of the optical disk 100, spiral tracks are formed from a predetermined start position on the inner peripheral side of the optical disk 100. In this track, sectors capable of storing data of a predetermined size are continuously formed, and addresses are continuously assigned to the sectors.

  Therefore, in the optical disc 100, if the address of a certain track is found, the distance (ie, radius) from the center of the optical disc 100 to the track is also found.

  In particular, in the optical disc apparatus 10, when the optical disc 100 is not particularly inclined (FIG. 4), the address where the focal point Fr1 of the red light beam Lr1 is located coincides with the address where the focal point Fr2 of the red light beam Lr2 is located. To do.

  However, in the optical disc apparatus 10, when the optical disc 100 itself has a warp as described above, or when the optical disc 100 is loaded with an inclination with respect to the optical disc apparatus 10, the red light beam Lr1 is emitted as shown in FIG. The address where the focal point Fr1 is located is different from the address where the focal point Fr2 of the red light beam Lr2 is located, and the respective radii are also different.

  The difference between the radii at this time is also a value corresponding to the tilt angle of the optical disc 100 in the target track TG1 due to the geometric relationship.

  Therefore, the optical disc apparatus 10 calculates the tilt angle based on the first address information MA1 and the second address information MA2, and adjusts the irradiation angle of each light beam such as the red light beam Lr1 according to the tilt angle. Has been made.

  Specifically, the signal processing unit 13 first includes the first address information MA1 obtained based on the red reflected light beam Lr3 by the first radius information acquisition unit 73C and the second radius information acquisition unit 73E (FIG. 8), and red The first address information MR1 and the second radius information MR2 are generated by converting the second address information MA2 obtained based on the reflected light beam Lr4 into the distance (ie, radius) from the center of the optical disc 100, respectively. .

  Here, the signal processing unit 13 stores a correspondence table TBL in which address information and radius information representing a distance from the center of the optical disc 100 (that is, radius) are associated with each other in advance in the ROM 74, and refers to the correspondence table TBL. Thus, the address information MA can be converted into the radius information MR.

  Incidentally, although the optical pickup 17 may slightly defocus the red light beam Lr4 with respect to the servo layer 105 due to the tilt of the optical disc 100, in the assumed tilt range, the detection signal U3 is detected from the detected signal U3. The 2-address information MA2 can be acquired.

  Subsequently, the signal processing unit 13 uses the radius difference calculation unit 75 to calculate a radius difference ΔR that is a difference between the first radius information MR1 and the second radius information MR72. Further, the signal processing unit 13 uses the inclination angle calculation unit 76 to use the radius difference ΔR, the refractive index n of the substrate 102 and the recording layer 101 of the optical disc 100, and the thickness d101 of the recording layer 101 as follows (6) ) To calculate the tilt angle θG of the optical disc 100 in the target track TG1, and supplies this to the tilt signal generator 78C of the drive controller 12.

  The tracking error signal STE2 described above represents the amount of deviation between the focal point Fr2 of the red light beam Lr2 and the target track TG2 in the servo layer 105 of the optical disc 100. That is, the tracking error signal STE2 also represents a value corresponding to a slight inclination of the optical disc 100 that cannot be obtained only from the first address information MA1 and the second address information MA2.

  Therefore, the drive control unit 12 generates the tilt drive signal SLD1 based on both the tilt angle θG and the tracking error signal STE2 by the tilt drive signal generation unit 78C, and supplies this to the actuator 19 (FIG. 6).

  At this time, the tilt drive signal generation unit 78C generates the tilt drive signal SLD1 that roughly tilts the objective lens 6 based on the tilt angle θG and tilts the objective lens 6 based on the tracking error signal STE2. .

  The actuator 19 tilts the objective lens 6 toward the inner circumference side or the outer circumference side of the optical disc 100 based on the tilt drive signal SLD1.

  As a result, the optical disc apparatus 10 causes the optical axis XL of the red light beams Lr1 and Lr2 and the blue light beam Lb1 to be the normal line XD of the servo layer 104 as shown in FIG. 10B corresponding to FIG. The optical disc 100 can be tilted so as to be close to each other, that is, to match the tilted state of the optical disc 100.

  Further, the optical disc apparatus 10 gradually brings the red light beam Lr2 closer to the target track TG2 of the servo layer 105 by repeating tilt control based on the tracking error signal STE2.

  As a result, the optical pickup 17 can accurately focus the focal point Fb of the blue light beam Lb1 on the target position PG located on the normal line XG in the target track TG1.

  In this way, the optical disc apparatus 10 calculates the tilt angle θG based on the first address information MA1 and the second address information MA2, and controls the tilt of the objective lens 6 in accordance with the tilt angle θG, whereby the blue light beam Lb1. The focus Fb is adjusted to the target position PG.

(4) Operation and Effect In the above configuration, the optical disc apparatus 10 collects the red light beam Lr1 on the servo layer 104 of the optical disc 100 by the objective lens 6 and the red light beam Lr1 is reflected by the servo layer 104. The reflected light beam Lr3 is detected by the photodetector 43.

  At this time, the optical disc apparatus 10 focuses the red light beam Lr1 on the target track TG1 by performing focus control and tracking control of the objective lens 6 based on the detection result of the red reflected light beam Lr3. At the same time, the optical disc apparatus 10 generates first address information MA1 indicating the address followed by the focal point Fr1 of the red light beam Lr1 on the servo layer 104 based on the detection result of the red reflected light beam Lr3.

  Further, the optical disc apparatus 10 condenses the red light beam Lr2 on the servo layer 105 of the optical disc 100, and detects the red reflected light beam Lr4 formed by reflecting the red light beam Lr2 by the servo layer 105 by the photodetector 44. At this time, the optical disc apparatus 10 generates second address information MA2 indicating the address followed by the focal point Fr2 of the red light beam Lr2 on the servo layer 105 based on the detection result of the red reflected light beam Lr4.

  Further, the optical disc apparatus 10 generates the radius information MR1 and MR2 based on the first address information MA1 and the second address information MA2, and calculates the tilt angle θG by substituting them into the equation (6). The objective lens 6 is tilted in the direction toward the inner or outer peripheral side of the optical disc 100 according to θG.

  Therefore, the optical disk apparatus 10 controls the tilt of the objective lens 6 based on the tilt angle θG, so that the optical axis XL of the red light beams Lr1 and Lr2 and the blue light beam Lb1 becomes the normal line XG of the servo layer 104 in the target track TG1. Since it can be tilted so as to be aligned, the focus Fb of the blue light beam Lb1 can be adjusted to the target position PG even when the optical disc 100 is tilted.

  For this reason, when the optical disc 100 is tilted, the optical disc apparatus 10 reproduces erroneous track information resulting from condensing the blue light beam Lb1 at a position other than the target position PG. It is also possible to prevent information from being recorded on the wrong track.

  At this time, since the optical disk apparatus 10 can calculate the tilt angle θG from the first address information MA1 and the second address information MA2, there is no need to provide a separate tilt sensor or the like, the configuration is complicated, and the weight of the optical pickup 17 is increased. No increase is required.

  Further, in the optical disc 100, the address in the servo layer 104 and the address in the servo layer 105 match with respect to the normal direction of the servo layer 104 and the like. Therefore, the optical disc apparatus 10 can use the same table for calculating the radius information MR1 from the first address information MA1 and the radius information MR2 from the second address information MA2, and stores a plurality of such tables. There is no need.

  Further, since the optical disc apparatus 10 generates the tilt drive signal SLD1 based on the tracking error signal STE2 in addition to the tilt angle θG, the optical disc is such that there is no difference between the first address information MA1 and the second address information MA2. The objective lens 6 can be tilt controlled in accordance with a slight inclination of 100.

  As a result, the optical disc apparatus 10 can adjust the focal point Fb of the blue light beam Lb1 to the target position PG much more accurately than in the case where the objective lens 6 is tilt-controlled based only on the tilt angle θG.

  According to the above configuration, the optical disc apparatus 10 performs the focus control and tracking control of the objective lens 6 to focus the red light beam Lr1 on the target track TG1, and the focus Fr1 of the red light beam Lr1 on the servo layer 104. Radius information MR1 and MR2 based on the first address information MA1 indicating the address followed by and the second address information MA2 indicating the address followed by the focal point Fr2 of the red light beam Lr2 on the servo layer 105. And the inclination angle θG is calculated using these and the equation (6). Then, the optical disk apparatus 10 tilts the objective lens 6 according to the tilt angle θG, thereby aligning the optical axes of the red light beams Lr1 and Lr2 and the blue light beam Lb1 so as to match the normal line XG of the servo layer 104 in the target track TG1. Since XL can be tilted, the focus Fb of the blue light beam Lb1 can be adjusted to the target position PG even when the optical disc 100 is tilted.

(5) Other Embodiments In the above-described embodiments, the case where the tilt drive signal SLD1 is generated based on the tracking error signal STE2 in addition to the tilt angle θG has been described. The tilt drive signal SLD1 may be generated based only on the tilt angle θG, for example, when tilt control can be performed with practically sufficient accuracy without using the tracking error signal STE2.

  In the above-described embodiment, the address information MA1 and the address information MA2 are converted into the radius information MR1 and MR2, the radius difference ΔR is calculated, and the inclination angle θG is calculated according to the equation (6). As described above, the present invention is not limited to this. For example, a correspondence table in which the address information MA1 and address information MA2 are directly associated with the inclination angle θG is stored in the ROM 74, and the address information MA1 and the address information according to the correspondence table. The inclination angle θG may be read based on MA2.

  Alternatively, for example, the radius information MR indicating the distance from the center of the optical disc 100 is recorded in the servo layers 104 and 105 at predetermined intervals, respectively, and the radius information MR is read from the servo layers 104 and 105 as it is. You may make it do. In short, it is only necessary to obtain position information indicating the focal positions of the red light beams Lr1 and Lr2 in the servo layers 104 and 105 based on the detection results of the red reflected light beams Lr3 and Lr4.

  Further, in the above-described embodiment, the address information MA1 and the address information MA2 are converted into the radius information MR1 and MR2, the radius difference ΔR is calculated, the tilt angle θG is calculated according to the equation (6), and then the tilt angle Although the case where the tilt drive signal SLD1 is generated based on θG has been described, the present invention is not limited to this. For example, the tilt drive signal SLD1 is directly generated from the radius difference ΔR without calculating the tilt angle θG. Further, the address information MA1, address information MA2, and tilt drive signal SLD1 are stored in association with each other in the above-described table, and the tilt drive signal SLD1 is read based on the address information MA1 and address information MA2. good.

  Further, in the above-described embodiment, the case where the address information in the servo layer 104 and the address information in the servo layer 105 are made to coincide with each other with respect to the normal direction of the servo layer 104 in the optical disc 100 has been described. For example, the address information in the servo layer 104 and the address information in the servo layer 105 may be described so as not to coincide with each other with respect to the normal direction of the servo layer 104.

  In this case, the point is that the distance (that is, the radius) from the center of the optical disc 100 at the focal point Fr1 of the red light beam Lr1 can be calculated based on the address read from the servo layer 104, and red based on the address read from the servo layer 105. It is only necessary to calculate the distance (that is, the radius) from the center of the optical disc 100 at the focal point Fr2 of the light beam Lr2.

  Further, in the above-described embodiment, the case where the guide grooves as tracks are formed in the servo layers 104 and 105 of the optical disc 100 has been described. However, the present invention is not limited to this, for example, the guide grooves are replaced. A pit or the like may be formed, or a guide groove and a pit may be combined, and the track is not limited to a spiral shape but may be a concentric shape. In short, it is sufficient that the optical disk apparatus 10 can recognize the address based on the red reflected light beam Lr3 or the like.

  Further, in the above-described embodiment, the case where the servo layer 104 is provided on the boundary surface between the recording layer 101 and the substrate 102 and the servo layer 105 is provided on the boundary surface between the recording layer 101 and the substrate 103 has been described. The present invention is not limited to this. For example, the servo layers 104 and 105 may be provided at various positions, for example, the servo layer 105 may be provided at the same distance from the substrates 102 and 103 in the recording layer 101. good. In this case, the inclination angle θG can be appropriately calculated by using the interval between the servo layers 104 and 105 in place of the thickness d101 of the recording layer 101 in the equation (6).

  Further, in the above-described embodiment, the objective lens 6 is tilt-controlled based on the tilt angle θG and the tracking error signal STE2, so that the optical axes XL of the red light beam Lr1 and Lr2 and the blue light beam Lb1 are Although the case where it was made to match | combine with the normal line XD was described, this invention is not restricted to this, You may make it match | combine the optical axis XL with the normal line XD by various means.

  For example, the optical pickup 17 is configured so that the red light beams Lr1 and Lr2 and the blue light beam Lb1 are reflected by a predetermined mirror and then incident on the objective lens 6, and based on the inclination angle θG and the tracking error signal STE2 The angle of the mirror may be changed, or the tilt angle of the spindle motor 15 in the optical disc apparatus 10 is adjusted so that the tilt of the entire optical disc 100 can be changed, and the tilt angle θG and the tracking error signal STE2 are used. In addition, the inclination angle of the spindle motor 15 (that is, the optical disc 100) may be adjusted.

  Further, in the above-described embodiment, the case where the red light beam Lr0 emitted from the single laser diode 31 is diffracted by the hologram plate 33 to generate the red light beams Lr1 and Lr2 has been described. The invention is not limited to this. For example, the red light beam Lr0 is separated into red light beams Lr1 and Lr2 by a beam splitter, and the divergent angles are adjusted using a predetermined lens, etc. Red light beams Lr1 and Lr2 may be generated from the red light beam Lr0 using an optical element.

  Alternatively, the red light beams Lr1 and Lr2 may be emitted from two independent laser diodes, and the optical paths may be combined using a prism or the like. In this case, the wavelengths of the red light beams Lr1 and Lr2 may be made different from each other, and the relationship between the wavelength of the light beam and the reflectance in the servo layers 104 and 105 of the optical disc 100 may be adjusted accordingly. Good. Accordingly, for example, it is possible to increase the transmittance of the red light beam Lr2 and the red reflected light beam Lr4 while increasing the reflectance of the red light beam Lr1 in the servo layer 104.

  Further, in the above-described embodiment, the wavelength of the red light beam Lr0 emitted from the laser diode 31 is about 660 [nm], and the wavelength of the light beam Lb1 emitted from the laser diode 51 is about 405 [nm]. Although the case where it did in the above was described, this invention is not restricted to this, Each other arbitrary wavelengths may be sufficient. In this case, the red light beams Lr1 and Lr2 are reflected by the servo layers 104 and 105, respectively, the recording mark RM can be formed in the recording layer 101 by the blue light beam Lb1, and the blue light beam Lb1 is reflected by the recording mark RM. It is only necessary to detect the blue reflected light beam Lb2.

  Further, in the above-described embodiment, the case where the substrates 102 and 103 are provided on the optical disc 100 has been described. However, the present invention is not limited to this, and for example, when the recording layer 101 has sufficient strength, One or both of the substrates 102 and 103 may be omitted.

  Further, in the above-described embodiment, the case where the focus error signal SFE1 is calculated based on the astigmatism method has been described. However, the present invention is not limited to this, and other various focus error signal generation methods are used. It may be calculated. In this case, the light beam irradiation pattern on the optical disc 100, the arrangement pattern of the detection area in the photodetector 43, etc. may be those corresponding to the focus error signal generation method.

  Further, in the above-described embodiment, the case where the tracking shift error signals STE1 and STE2 are calculated based on the push-pull method has been described. However, the present invention is not limited to this, and for example, the three-spot method or DPP (Differential) The calculation may be performed according to other various tracking shift error signal generation methods such as a push pull method. In this case, the light beam irradiation pattern on the optical disc 100, the arrangement pattern of the detection areas in the photodetectors 43 and 44, and the like may be those corresponding to the tracking shift error signal generation method.

  Further, in the above-described embodiment, the case where the present invention is applied to the optical disc apparatus 10 that records and reproduces information on the optical disc 100 has been described. The present invention may be applied to an optical disk reproducing apparatus that performs only reproduction of the above.

  Further, in the above-described embodiment, the light beam adjustment unit 80 as the light beam adjustment unit, the objective lens 6 as the objective lens, the photodetector 43 as the first detection unit, and the first position information acquisition unit. A first address information acquisition unit 22C and a first radius information acquisition unit 23C; a photo detector 44 as a second detection unit; a second address information acquisition unit 22E and a second radius information acquisition unit 23E as second position information acquisition units; The case where the optical disc apparatus 10 as the optical disc apparatus is configured by the radius difference calculation unit 25 and the tilt angle calculation unit 26 as the calculation unit and the tilt drive signal generation unit 28C as the tilt control unit has been described. However, the present invention is not limited thereto, and other light beam adjustment units having various circuit configurations, an objective lens, a first detection unit, and a first position information acquisition unit. A second detection unit, and a second position information acquisition unit, a calculation unit may be configured to an optical disk apparatus by the tilt control unit.

  The present invention can also be used in an optical disc apparatus that records information such as video, audio, or computer data on an optical disc and reproduces the information from the optical disc.

It is a basic diagram with which it uses for description of irradiation of the several light beam with respect to an optical disk. It is a basic diagram with which it uses for description of the shift | offset | difference of the focus position by the inclination of an optical disk. 1 is a schematic perspective view showing an external configuration of an optical disc. It is a basic diagram which shows the internal structure of an optical disk. 1 is a schematic diagram illustrating an overall configuration of an optical disc device. It is a basic diagram which shows the structure of an optical pick-up. It is a basic diagram which shows the structure of a photodetector. It is a basic block diagram which shows the structure of a signal processing part and a drive processing part. It is a basic diagram which shows the structure of a light beam adjustment part. It is a basic diagram with which it uses for description of adjustment of the irradiation angle of the light beam with respect to an optical disk.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 10 ... Optical disk apparatus, 2, 100 ... Optical disk, 2A, 104, 105 ... Servo layer, 2B, 101 ... Recording layer, 6 ... Objective lens, 11 ... Control part, 12 ... Drive control , 13... Signal processing unit, 15... Spindle motor, 17... Optical pickup, 19... Actuator, 31, 51 .. laser diode, 33 .. hologram plate, 43, 44, 62. ... Relay lens, 72C... First address information acquisition unit, 72E... Second address information acquisition unit, 73C... First radius information acquisition unit, 73E. Calculation unit, 76... Tilt angle calculation unit, 78C... Tilt drive signal generation unit, 80... Light beam adjustment unit, Lr1, Lr2... Red light beam, Lr3, Lr4. , Lb1... Blue light beam, Lb2... Blue reflected light beam, U1A, U1B, U1C, U1D, U2A, U2B, U2C, U2D, U3... Detection signal, MA1. Second address information, MR1... First radius information, MR2... Second radius information, ΔR... Radius difference, .theta.G... Tilt angle, SLD1.

Claims (9)

A light beam adjusting unit for adjusting a convergent divergence state in the first light beam and the second light beam for recording information on the recording layer of the optical disc or for determining the irradiation position of the information light beam for reproducing the information from the recording layer; ,
An objective lens that separates the focal point of the first light beam and the focal point of the second light beam by a predetermined distance by condensing the first light beam, the second light beam, and the information light beam, respectively;
A first detector for detecting a first reflected light beam formed by reflecting the first light beam by a first servo layer on which position information for specifying a position in the recording layer of the optical disc is recorded;
A first position information acquisition unit configured to acquire first position information representing a focal position of the first light beam in the first servo layer based on a detection result of the first reflected light beam;
The second light beam is transmitted through the first servo layer, and is separated from the first servo layer by the predetermined distance and is reflected by the second servo layer on which the position information is recorded. A second detector that
A second position information acquisition unit that acquires second position information indicating a focal position of the second light beam in the second servo layer based on the detection result of the second reflected light beam;
A calculation unit for calculating an inclination angle of the optical disc based on the first position information and the second position information and an interval between the first servo layer and the second servo layer;
An inclination control unit for controlling the irradiation angle of the first light beam, the second light beam, and the information light beam to the optical disc in accordance with the inclination angle so as to incline toward the inner circumference side or the outer circumference side of the optical disc. An optical disc device characterized by the above. The second servo layer is
The same position information as the first servo layer is written at a position corresponding to the first servo layer with respect to the normal direction of the first servo layer,
The second position information acquisition unit
The optical disk apparatus according to claim 1, wherein the second position information is acquired by a calculation process equivalent to that of the first position information acquisition unit. The first servo layer and the second servo layer are
Continuous address information is written as the position information on a track formed in a spiral or concentric circle,
The calculation unit is
The first address information representing the first position information and the second address information representing the second position information are converted into first radius information and second radius information representing a distance from the center of the optical disc, and the first radius is converted. The optical disc apparatus according to claim 2, wherein the tilt angle of the optical disc is calculated based on information and a difference value between the second radius information and an interval between the first servo layer and the second servo layer. The first servo layer and the second servo layer are
Radius information indicating the distance from the center of the optical disc is written as the position information on the tracks formed in a spiral shape or concentric shape, respectively.
The calculation unit is
The tilt angle of the optical disk is determined based on the difference between the first radius information representing the first position information and the second radius information representing the second position information and the distance between the first servo layer and the second servo layer. The optical disk device according to claim 1, wherein the optical disk device is calculated. The tilt control unit
By controlling the inclination of the objective lens toward the inner or outer periphery of the optical disc, the irradiation angles of the first light beam, the second light beam, and the information light beam can be set to the inner or outer periphery of the optical disc. The optical disc apparatus according to claim 1, wherein the optical disc apparatus is controlled to tilt toward the side. Based on the detection result of the second reflected light beam, a tracking error signal is generated according to the amount of deviation between the focal point of the second light beam in the second servo layer and the target track to be irradiated with the second light beam. An error signal generator
The tilt control unit
An irradiation angle of the first light beam, the second light beam, and the information light beam to the optical disc is controlled so as to cancel the tracking error signal based on the tilt angle and the tracking error signal. The optical disc apparatus according to claim 1. The light beam adjusting unit is
By using a predetermined light separator, a light beam emitted from a predetermined light source is separated into the first light beam and the second light beam, and a convergent divergence state in the first light beam and the second light beam is obtained. The optical disk apparatus according to claim 1, wherein the optical disk apparatus is adjusted. The light separator is
8. The light beam is separated into the first light beam and the second light beam by the action of a hologram, and the convergent and divergent state in the first light beam and the second light beam is adjusted. The optical disk device described. After adjusting the convergence / divergence state of the first light beam and the second light beam for recording the information on the recording layer of the optical disc or determining the irradiation position of the information light beam for reproducing the information from the recording layer, the first A light beam condensing step in which one light beam, the second light beam, and the information light beam are incident on a predetermined objective lens, and the focal point of the first light beam is separated from the focal point of the second light beam by a predetermined interval. When,
A first detection step of detecting a first reflected light beam formed by reflecting the first light beam by a first servo layer on which position information for specifying a position of the optical disc in the recording layer is recorded;
A first position information acquisition step for acquiring first position information representing a focal position of the first light beam in the first servo layer based on the detection result of the first reflected light beam;
The second light beam is transmitted through the first servo layer, and is separated from the first servo layer by the predetermined distance and is reflected by the second servo layer on which the position information is recorded. A second detecting step,
A second position information acquisition step for acquiring second position information representing a focal position of the second light beam in the second servo layer based on the detection result of the second reflected light beam;
A calculation step of calculating an inclination angle of the optical disc based on the first position information and the second position information and an interval between the first servo layer and the second servo layer;
A tilt control step for controlling the irradiation angle of the first light beam, the second light beam, and the information light beam to the optical disc in accordance with the tilt angle so as to tilt toward the inner or outer peripheral side of the optical disc. A method of adjusting a light beam irradiation angle.

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