JP5251990B2 - Optical information recording medium - Google Patents

Description

  The present invention relates to an optical information recording medium, and is suitably applied to a recording medium that records information using a light beam and reproduces the information using a light beam, for example.

  Conventionally, as an optical information recording / reproducing apparatus, an optical disk apparatus using a disk-shaped optical disk as an information recording medium has been widely used. As an information recording medium, a CD (Compact Disc), a DVD (Digital Versatile Disc), and a Blu are generally used. -Ray Disc (registered trademark, hereinafter referred to as BD) or the like is used.

  In such an optical disc apparatus, various kinds of information such as various contents such as music contents and video contents, or various data for a computer 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 an increase in the number of contents to be recorded on one optical disc has been demanded. It has been demanded.

  Therefore, as one of the techniques for increasing the capacity of an optical disk, there has been proposed one in which information is recorded by forming a minute hologram in a recording medium by interfering with two light beams. (For example, refer to Patent Document 1).

JP 2006-78834 A (FIG. 1)

  However, the optical disc apparatus having such a configuration requires high-level control such that the focal positions of two types of light beams are simultaneously adjusted at a location where information on the rotating and vibrating optical disc is to be recorded, and the configuration becomes complicated and stable. There is a problem that it is difficult to record or reproduce the recorded information.

  The present invention has been made in consideration of the above points, and intends to propose an optical information recording medium capable of stably recording or reproducing information.

  In order to solve such problems, in the recording medium of the present invention, a resin having an organometallic compound and having photoreactivity is cured by a photoreaction caused by irradiation of predetermined initialization light, and information is recorded. When the predetermined recording light is condensed, the temperature in the vicinity of the focal point of the recording light rises, the organometallic compound is altered to form a recording mark, and the predetermined reading light is irradiated when reproducing information. An arbitrary position of the recording light in the first and second recording layers is sandwiched between the first and second recording layers for reproducing the information based on the corresponding return light and the first and second recording layers. In order to adjust the position, a reflection layer that reflects servo light having a wavelength different from that of the recording light irradiated and reflects and transmits the recording light is provided.

  As a result, the recording marks can be formed on the respective recording layers by the irradiation of the respective recording lights, and the position in the depth direction of each recording mark can be determined with the reflective layer as a reference by the servo light.

  According to the present invention, a recording mark can be formed on each recording layer by irradiation of each recording light, and the position in the depth direction of each recording mark can be determined by using the servo layer as a reference, Thus, an optical information recording medium capable of stably recording or reproducing information can be realized.

1 is a schematic diagram showing an external configuration of an optical disc. It is a basic diagram which shows the internal structure of an optical disk. It is an approximate line figure used for explanation of formation of a recording mark. It is an approximate line figure used for explanation of initialization of an optical disc. It is a basic diagram which shows the structure of an optical disk device. It is a basic diagram which shows the structure of an optical pick-up. It is a basic diagram with which it uses for description of the optical path of a red light beam. It is a basic diagram which shows the structure of the detection area | region in a photodetector. It is a basic diagram with which it uses for description of the optical path of a blue light beam. It is a basic diagram with which it uses for description of the selection of the light beam by a pinhole. It is a basic diagram which shows the structure (1) of the optical disk by other embodiment. It is a basic diagram which shows the structure (2) of the optical disk by other embodiment.

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

(1) Configuration of Optical Disc (1-1) Layer Structure of Optical Disc First, an optical disc 100 used as an optical information recording medium in the present invention will be described. As shown in the external view in FIG. 1, the optical disc 100 as a whole is formed in a disk shape having a diameter of about 120 [mm], similar to the 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. 2, 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 substrates 102 and 103. Yes.

  Incidentally, the thickness t1 of the recording layer 101 is about 0.3 [mm], and the thicknesses t2 and t3 of the substrates 102 and 103 are both about 0.6 [mm].

  The substrates 102 and 103 are made of, for example, a material such as polycarbonate or glass, and both of them transmit light incident from one surface to 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. In addition, about the surface of the board | substrates 102 and 103, unnecessary reflection may be made to be prevented by anti-reflective coating.

  The optical disc 100 also has a reflective film 104 as a reflective layer on the boundary surface between the recording layer 101 and the substrate 103. The reflection film 104 is made of a dielectric multilayer film or the like, and reflects both the blue light beam Lb1 made of blue laser light having a wavelength of 405 [nm] and the red light beam Lr1 made of red laser light having a wavelength of 660 [nm]. .

  The reflection film 104 forms a guide groove for tracking servo. Specifically, a spiral track is formed by lands and grooves similar to a general BD-R (Recordable) disk or the like. . This track is given an address consisting of a series of numbers for each predetermined recording unit, and the track on which information is recorded or reproduced can be specified by the address.

  Note that pits or the like may be formed on the reflective film 104 (that is, the boundary surface between the recording layer 101 and the substrate 103) instead of the guide grooves, or the guide grooves and pits may be combined.

  When the red light beam Lr1 is irradiated from the substrate 102 side, the reflection film 104 reflects this toward the substrate 102 side. Hereinafter, the light beam reflected at this time is referred to as a red light beam Lr2.

  For example, in the optical disc apparatus, the red light beam Lr2 is used to adjust the red light focus Fr of the red light beam Lr1 collected by a predetermined objective lens OL to a target track (hereinafter referred to as a target track). It is assumed that the objective lens OL is used for position control (that is, focus control and tracking control).

  In practice, when information is recorded on the optical disc 100, as shown in FIG. 2, the red light beam Lr1 is condensed by the position-controlled objective lens OL and focused on the target track of the reflective film 104.

  Further, the blue light beam Lb1 is collected by the objective lens OL1 while sharing the optical axis Lx with the red light beam Lr1 and is focused on a position corresponding to the desired track in the recording layer 101 through the substrate 102. The At this time, the blue light focus Fb of the blue light beam Lb1 is located closer to the red light focus Fr on the common optical axis Lx with respect to the objective lens OL, that is, on the “near side”.

  At this time, in the recording layer 101, when the blue light beam Lb1 is the recording blue light beam Lb1w used during the recording process, the recording blue light beam Lb1w is condensed and becomes equal to or higher than a predetermined intensity. A recording mark RM is formed in the portion (that is, around the blue light focus Fb). For example, when the wavelength λ of the blue light beam Lb1 is 405 [nm], the numerical aperture NA of the objective lens OL is 0.5, and the refractive index n of the objective lens OL is 1.5, the diameter RMr = 1 [ μm] and a recording mark RM having a height RMh = 10 [μm] is formed.

  Further, the optical disc 100 is designed such that the thickness t1 (= 0.3 [mm]) of the recording layer 101 is sufficiently larger than the height RMh of the recording mark RM. For this reason, the optical disc 100 records the recording mark RM while switching the distance from the reflective film 104 in the recording layer 101 (hereinafter referred to as the depth), so that FIGS. As shown, multilayer recording can be performed in which a plurality of mark recording layers are stacked in the thickness direction of the optical disc 100.

  In this case, the depth of the recording mark RM is changed by adjusting the depth of the blue light focal point Fb of the recording blue light beam Lb1w in the recording layer 101 of the optical disc 100. For example, in the optical disc 100, when the distance p3 between the mark recording layers is set to about 15 [μm] in consideration of the mutual interference between the recording marks RM, about 20 mark recording layers are formed in the recording layer 101. can do. The distance p3 may be set to various values other than about 15 [μm] 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 OL1 is focused on the target track of the reflective film 104, as in the case of recording the information. The position of the objective lens OL is controlled.

  Further, in the optical disc 100, the blue light focal point Fb of the read blue light beam Lb1r condensed through the same objective lens OL corresponds to the “front side” of the target track in the recording layer 101, and the target depth. (Hereinafter, this is referred to as a target mark position).

  At this time, the recording mark RM recorded at the position of the blue light focus Fb reflects the reading blue light beam Lb1r due to the difference in refractive index from the surroundings, and from the recording mark RM recorded at the target mark position, A blue light beam Lb2 is generated.

  As described above, when information is recorded on the optical disc 100, the position at which the blue light focus Fb is irradiated in the recording layer 101 by using the position-controlling red light beam Lr1 and the recording blue light beam Lb1w, That is, a recording mark RM is formed as the information at a target mark position on the reflective film 104 that is on the near side of the target track and has a target depth.

  Further, when recorded information is reproduced, the optical disc 100 uses the red light beam Lr1 for position control and the blue light beam Lb1r for reading to record at the position of the blue light focus Fb, that is, the target mark position. A blue light beam Lb2 is generated from the recorded mark RM.

(1-2) Configuration of Recording Layer Next, the configuration of the recording layer 101 described above will be described.

  As shown in FIG. 4, the recording layer 101 is made of a photopolymerizable photopolymer, and an uncured resin 101a made of a uniformly dispersed monomer and a photopolymerization initiator is sandwiched between the substrates 102 and 103. For example, the initialization light Lp1 is irradiated from an initialization light source 110 made of a high pressure mercury lamp, a high pressure meta-hara lamp, a solid laser, a semiconductor laser, or the like, and the uncured resin 101a is polymerized.

  The uncured resin 101a is composed of, for example, a radical polymerization compound and a photopolymerization initiator, or is composed of a cation polymerization compound and a cation generation type photopolymerization initiator. In addition, the photopolymerizable resin, photocrosslinkable resin, and photopolymerization initiator, of which the photopolymerization initiator, in particular, adjusts the wavelength at which photopolymerization easily occurs to a desired wavelength by appropriately selecting the material. It is possible.

  Further, a small amount of an organometallic compound and / or an inorganic metal compound is mixed in the uncured resin 101a, and a photopolymerization reaction, a photocrosslinking reaction, or both reactions are caused by irradiation with the initialization light Lp1. Has been made.

  As described above, the optical disc 100 is formed in a thin plate shape as a whole and is configured to substantially transmit light. The resin in the recording layer 101 is polymerized and / or crosslinked by the initialization process, and further, the recording layer A small amount of an organometallic compound is contained in 101.

  In the recording layer 101, when the blue light beam Lb1 having a predetermined intensity or more at the time of recording processing is condensed at a target mark position in the recording layer 101, a recording mark RM is formed. This is because the blue light beam Lb1 is condensed in the recording layer 101 and the temperature locally rises, whereby the organometallic compound is thermally changed and denatured, and a metal compound such as fluoride or oxide or It is considered that pure metal is precipitated and agglomerated.

  That is, in the recording layer 101, among the resin containing the organometallic compound, the portion where the recording blue light beam Lb1w is condensed and locally heated is altered, and the metal compound or pure metal is precipitated, It is assumed that the refractive index changes and the reflectance is improved.

  In practice, the uncured resin 101a is, for example, an acrylic ester monomer (p-cumylphenol ethylene oxide-added acrylic ester) and a urethane bifunctional acrylate oligomer of 40:60 (weight ratio) and an oligomer weight ratio of 2%. (Bis (η-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, which is a metal compound and a photopolymerization initiator) (Ciba Specialty Chemicals Irg-784, hereinafter referred to as Irg-784) is produced by mixing and degassing in a dark room.

The recording layer 101 is sandwiched between the substrate 102 and the substrate 103 on which the reflective film 104 is formed in a state where the uncured resin 101a is spread on the substrate 102, and then initialized by a high-pressure mercury lamp. It is produced by irradiating 60 [min] of initialization light Lp1 (with a power density of 30 mW / cm ^{2 at a} wavelength of 365 [nm]) by the light source 110 and photocuring.

  In this initialization process, the recording layer 101 is initialized (precured) when the resin undergoes polymerization, crosslinking, or both in the interior due to the occurrence of a photopolymerization reaction and / or a photocrosslinking reaction as a whole. The As a result, the refractive index of the recording layer 101 changes as a whole as compared with that before irradiation of the initialization light. Incidentally, the recording layer 101 is almost transparent in the photocured state, and transmits the irradiated light at a high rate.

  Thus, in the vicinity of the target position in the recording layer 101, the recording blue light beam Lb1w is condensed and locally heated, so that the recording mark RM is a portion where the reflectance is locally higher than the surrounding area. Is formed and information is recorded. As a result, when the recording mark RM is irradiated with the read blue light beam Lb1r, the blue light beam Lb2 having a high luminance can be detected. Incidentally, it is difficult to visually confirm the recording mark RM.

  On the other hand, when the reading blue light beam Lb1r is irradiated to a portion where the recording mark RM is not recorded (that is, an unrecorded portion), a very weak blue light beam Lb2 is detected. That is, when the optical information recording / reproducing apparatus 20 reproduces information from the optical disc 100, it can be seen that the detected intensity of the blue light beam Lb2 varies greatly depending on the presence or absence of the recording mark RM.

  This is because, for example, the optical disk apparatus 20 can record information on the optical disk 100 by associating the code “0” or “1” with the presence or absence of the recording mark RM, and when the information is reproduced, the target position at that time This indicates that it is possible to determine with high accuracy whether or not the recording mark RM is recorded, that is, whether the code “0” or “1” is recorded as information.

  As described above, the optical disc apparatus 20 uses the optical disc 100 to focus the recording blue light beam Lb1w on the recording layer 101 in which the organometallic compound is blended and photocured in advance, thereby increasing the temperature. Alternatively, it is possible to perform information recording in which pure metal is deposited to form the recording mark RM. Further, the optical disc apparatus 20 can perform information reproduction by detecting the blue light beam Lb2 having a high luminance by irradiating the read blue light beam Lb1r to the recording mark RM.

(2) Configuration of Optical Disc Device Next, the optical disc device 20 corresponding to the optical disc 100 described above will be described. As shown in FIG. 5, the optical disc apparatus 20 is configured to perform overall control by a control unit 21.

  The control unit 21 is mainly configured by a CPU (Central Processing Unit) (not shown), reads various programs such as a basic program and an information recording program from a ROM (Read Only Memory) (not shown), and stores them in a RAM (Random) (not shown). Various processes such as an information recording process are executed by expanding in (Access Memory).

  For example, when the control unit 21 receives an information recording command, recording information, and recording address information from an external device (not shown) with the optical disc 100 loaded, the control unit 21 supplies the driving command and recording address information to the driving control unit 22. The recording information is supplied to the signal processing unit 23. Incidentally, the recording address information is information indicating an address at which the recording information is to be recorded among the addresses given to the recording layer 101 of the optical disc 100.

  The drive control unit 22 drives and controls the spindle motor 24 in accordance with the drive command to rotate the optical disc 100 at a predetermined rotation speed, and controls the sled motor 25 to drive the optical pickup 26 with the moving shafts 25A and 25B. Are moved to a position corresponding to the recording address information in the radial direction of the optical disc 100 (that is, the inner circumferential direction or the outer circumferential direction).

  The signal processing unit 23 generates a recording signal by performing various signal processing such as predetermined encoding processing and modulation processing on the supplied recording information, and supplies the recording signal to the optical pickup 26.

  The optical pickup 26 performs focus control and tracking control based on the control of the drive control unit 22 (FIG. 4), so that a track indicated by recording address information in the recording layer 101 of the optical disc 100 (hereinafter referred to as a target track). The recording position of the recording blue light beam Lb1w is aligned with the recording mark RM corresponding to the recording signal from the signal processing unit 23 (details will be described later).

  When the control unit 21 receives, for example, an information reproduction command and reproduction address information indicating the address of the recording information from an external device (not shown), the control unit 21 supplies the drive command to the drive control unit 22 and also reproduces the reproduction processing command. Is supplied to the signal processing unit 23.

  As in the case of recording information, the drive control unit 22 controls the spindle motor 24 to rotate the optical disc 100 at a predetermined rotational speed, and controls the sled motor 25 to control the optical pickup 26 for reproduction addressing. Move to a position corresponding to the information.

  The optical pickup 26 performs focus control and tracking control based on the control of the drive control unit 22 (FIG. 4), thereby reading out the track indicated by the reproduction address information (that is, the target track) in the recording layer 101 of the optical disc 100. The irradiation position of the blue light beam Lb1r is aligned, and a light beam with a predetermined light amount is irradiated. At this time, the optical pickup 26 detects the blue light beam Lb2 generated from the recording mark RM of the recording layer 101 in the optical disc 100, and supplies a detection signal corresponding to the amount of light to the signal processing unit 23 ( Details will be described later).

  The signal processing unit 23 generates reproduction information by performing various signal processing such as predetermined demodulation processing and decoding processing on the supplied detection signal, and supplies the reproduction information to the control unit 21. In response to this, the control unit 21 sends the reproduction information to an external device (not shown).

  As described above, the optical disc apparatus 20 controls the optical pickup 26 by the control unit 21 to record information at the target mark position in the recording layer 101 of the optical disc 100 and reproduce information from the target mark position. ing.

(3) Configuration of Optical Pickup Next, the configuration of the optical pickup 26 will be described. As shown in FIG. 6, the optical pickup 26 has a servo optical system 30 for servo control and an information optical system 50 for reproducing or recording information.

  The optical pickup 26 uses a servo optical system for the red light beam Lr1 as servo light emitted from the laser diode 31 and the blue light beam Lb1 (reading blue light beam Lb1r or recording blue light beam Lb1w) emitted from the laser diode 51, respectively. 30 and the information optical system 50, the light enters the same objective lens 40 and irradiates the optical disc 100 respectively.

(3-1) Optical Path of Red Light Beam As shown in FIG. 7, the servo optical system 30 irradiates the optical disk 100 with the red light beam Lr <b> 1 via the objective lens 40 and reflects the red light beam reflected on the optical disk 100. The light beam Lr2 is received by the photodetector 43.

  In other words, the laser diode 31 can emit red laser light having p-polarized light having a wavelength of about 660 [nm]. Actually, the laser diode 31 emits a predetermined amount of red light beam Lr1 made of divergent light based on the control of the control unit 21 (FIG. 5) and makes it incident on the collimator lens 33. The collimator lens 33 converts the red light beam Lr1 from diverging light to parallel light and makes it incident on the polarization beam splitter 34.

  The polarization beam splitter 34 reflects or transmits the light beam on the reflection / transmission surface 34 </ b> S at a different rate depending on the polarization direction of the light beam. The reflection / transmission surface 34 transmits almost all of the p-polarized light beam and reflects almost all of the s-polarized light beam.

  Then, the polarization beam splitter 34 transmits almost all of the red light beam Lr1 composed of p-polarized light and enters the quarter-wave plate 36.

  The quarter-wave plate 36 converts the red light beam Lr1 made of p-polarized light into, for example, left-circularly polarized light, and enters the dichroic prism 37. The dichroic prism 37 is configured to reflect or transmit the light beam according to the wavelength of the light beam by the transmission / reflection surface 37S, thereby reflecting the red light beam Lr1 and entering the objective lens 40.

  The objective lens 40 collects the red light beam Lr1 and irradiates it toward the reflective film 104 of the optical disc 100. At this time, as shown in FIG. 2, the red light beam Lr1 is transmitted through the substrate 102 and reflected by the reflective film 104. The red light beam Lr1 travels in the opposite direction to the red light beam Lr1, and in the polarization direction opposite to the red light beam Lr1. The resulting red light beam Lr2.

  Thereafter, the red light beam Lr <b> 2 is converted into parallel light by the objective lens 40 and then incident on the dichroic prism 37. The dichroic prism 37 reflects the red light beam Lr 2 and makes it incident on the quarter-wave plate 36.

  The quarter-wave plate 36 converts the red light beam Lr <b> 2 that is right-circularly polarized light into s-polarized light, and enters the polarizing beam splitter 34. The polarization beam splitter 34 reflects the red light beam Lr 2 made of s-polarized light and enters the multi-lens 41.

  The multi-lens 41 converges the red light beam Lr2 and gives astigmatism by the cylindrical lens 42, and then irradiates the photodetector 43 with the red light beam Lr2.

  By the way, in the optical disc apparatus 20, since the surface blur etc. in the rotating optical disc 100 may occur, the relative position of the target track with respect to the objective lens 40 may vary.

  Therefore, in order to make the red light focal point Fr (FIG. 2) of the red light beam Lr1 follow the target track, the red light focal point Fr is in a focus direction that is a close direction or a separation direction with respect to the optical disc 100 and an inner peripheral side of the optical disc 100. It is necessary to move in the tracking direction which is the direction or the outer peripheral side direction.

  Therefore, the objective lens 40 can be driven in the biaxial direction of the focus direction and the tracking direction by the biaxial actuator 40A.

  Further, in the servo optical system 30 (FIG. 7), the in-focus state when the red light beam Lr1 is condensed by the objective lens 40 and applied to the reflection film 104 of the optical disc 100 is focused, and the red light beam Lr2 is collected by the multilens 41. The optical positions of various optical components are adjusted so as to be reflected in a focused state when the light is irradiated and irradiated on the photodetector 43.

  As shown in FIG. 8, 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 light beam Lr2. 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 irradiated onto the reflective film 104 (FIG. 3).

  The photodetector 43 detects a part of the red light beam Lr2 by the detection areas 43A, 43B, 43C, and 43D, respectively, and generates detection signals SDAr, SDBr, SDCr, and SDDr according to the detected light amount. Is sent to the signal processing unit 23 (FIG. 4).

  The signal processing unit 23 performs focus control by a so-called astigmatism method, calculates a focus error signal SFEs according to the following equation (1), and supplies this to the drive control unit 22.

  The focus error signal SFEs represents the amount of deviation between the red light focus Fr of the red light beam Lr1 and the reflective film 104 of the optical disc 100.

  The signal processing unit 23 performs tracking control by a so-called push-pull method. The signal processing unit 23 calculates a tracking error signal STEr according to the following equation (2) and supplies it to the drive control unit 22.

  This tracking error signal STEr represents the amount of deviation between the red light focus Fr and the target track in the reflective film 104 of the optical disc 100.

  The drive control unit 22 generates a focus drive signal SFDr based on the focus error signal SFEs and supplies the focus drive signal SFDr to the biaxial actuator 40A, so that the red light beam Lr1 is aligned with the reflective film 104 of the optical disc 100. The objective lens 40 is feedback-controlled (that is, focus control) so as to focus.

  The drive control unit 22 generates a tracking drive signal STDr based on the tracking error signal STEr and supplies the tracking drive signal STDr to the biaxial actuator 40A, so that the red light beam Lr1 is reflected on the reflective film 104 of the optical disc 100. The objective lens 40 is feedback controlled (that is, tracking control) so as to focus on the target track.

  As described above, the servo optical system 30 irradiates the reflection film 104 of the optical disc 100 with the red light beam Lr1, and supplies the light reception result of the red light beam Lr2 that is the reflected light to the signal processing unit 23. In response to this, the drive control unit 22 performs focus control and tracking control of the objective lens 40 so that the red light beam Lr1 is focused on the target track of the reflective film 104.

(3-2) Optical Path of Blue Light Beam On the other hand, in the information optical system 50, as shown in FIG. 9 corresponding to FIG. 6, the optical disk 100 is irradiated with the blue light beam Lb1 emitted from the laser diode 51 via the objective lens 40. At the same time, the photodetector 60 receives the blue light beam Lb2 reflected by the optical disc 100.

  That is, the laser diode 51 can emit blue laser light having a wavelength of about 405 [nm]. In practice, the laser diode 51 emits a blue light beam Lb1 having a predetermined amount of light, which is a divergent light, based on the control of the control unit 21 (FIG. 5) and enters the collimator lens 52. The collimator lens 52 converts the blue light beam Lb1 from diverging light into parallel light, and enters the polarization beam splitter 54.

  The polarization beam splitter 54 reflects or transmits the light beam on the reflection / transmission surface 54S according to the polarization direction of the light beam. For example, the reflection / transmission surface 54S transmits almost all of the p-polarized light beam and reflects almost all of the s-polarized light beam.

  The polarization beam splitter 54 transmits the blue light beam Lb1 made of p-polarized light and enters the quarter wavelength plate 57 via an LCP (Liquid Crystal Panel) 56 that corrects spherical aberration and the like.

  The quarter-wave plate 57 converts the blue light beam Lb1 from p-polarized light to, for example, left circularly-polarized light and enters the relay lens 58.

  The relay lens 58 converts the blue light beam Lb1 from parallel light into convergent light by the movable lens 58A, converts the blue light beam Lb1 that has become divergent light after convergence into the converged light again by the fixed lens 58B, and transmits it to the mirror 59. Make it incident.

  Here, the movable lens 58A is moved in the optical axis direction of the blue light beam Lb1 by an actuator (not shown). In practice, the relay lens 58 can change the convergence state of the blue light beam Lb1 emitted from the fixed lens 58B by moving the movable lens 58A by an actuator based on the control of the control unit 21 (FIG. 5). Has been made.

  The mirror 59 reflects the blue light beam Lb1, thereby reversing the polarization direction of the blue light beam Lb1, which is circularly polarized light (for example, from left circularly polarized light to right circularly polarized light) and deflecting the traveling direction thereof, so that the dichroic prism 37 is incident. The dichroic prism 37 transmits the blue light beam Lb1 through the reflection / transmission surface 37S and enters the objective lens 40.

  The objective lens 40 collects the blue light beam Lb1 and irradiates the optical disc 100 with it. At this time, the blue light beam Lb1 is transmitted through the substrate 102 and focused in the recording layer 101 as shown in FIG.

  Here, the position of the blue light focal point Fb of the blue light beam Lb1 is determined by the convergence state when it is emitted from the fixed lens 58B of the relay lens 58. That is, the blue light focal point Fb moves in the recording layer 101 in the focus direction according to the position of the movable lens 58A.

  Specifically, the information optical system 50 is designed so that the moving distance of the movable lens 58A and the moving distance of the blue light focus Fb of the blue light beam Lb1 are substantially proportional to each other. ], The blue light focus Fb of the blue light beam Lb1 is moved by 30 [μm].

  In practice, in the information optical system 50, the position of the movable lens 58A is controlled by the control unit 21 (FIG. 5), so that the blue light focus Fb of the blue light beam Lb1 in the recording layer 101 of the optical disc 100 (FIG. 2). The depth d1 (that is, the distance from the reflective film 104) is adjusted so that the blue light focal point Fb matches the target mark position.

  In this way, the information optical system 50 irradiates the blue light beam Lb1 through the servo-controlled objective lens 40 by the servo optical system 30 to thereby change the tracking direction of the blue light focus Fb of the blue light beam Lb1 to the target mark position. Further, by adjusting the depth d1 of the blue light focus Fb according to the position of the movable lens 58A in the relay lens 58, the focus direction of the blue light focus Fb is made to match the target mark position. Yes.

  The blue light beam Lb1 is focused on the blue light focus Fb by the objective lens 40 during the recording process for recording information on the optical disc 100, and forms a recording mark RM at the blue light focus Fb.

  On the other hand, the blue light beam Lb1 is a reading light beam condensed at the blue light focal point Fb when the recording mark RM is recorded at the blue light focal point Fb during the reproduction process of reading information recorded on the optical disc 100. Fb1r is reflected by the recording mark RM as a blue light beam Lb2, and enters the objective lens 40. At this time, the polarization direction of the circularly polarized light of the blue light beam Lb2 is reversed (for example, from right circularly polarized light to left circularly polarized light) due to reflection by the recording mark RM.

  On the other hand, when the recording mark RM is not recorded at the blue light focal point Fb, the blue light beam Lb1 diverges again after converging at the blue light focal point Fb, is reflected by the reflective film 104, and is reflected as the blue light beam Lb2. 40 is incident. At this time, the rotation direction of the circularly polarized light of the blue light beam Lb2 is reversed (for example, from the right circularly polarized light to the left circularly polarized light) by reflection by the reflective film 104.

  The objective lens 40 converges the blue light beam Lb <b> 2 to some extent and enters the dichroic prism 37. The dichroic prism 37 transmits the blue light beam Lb 2 and enters the mirror 59.

  The mirror 59 reflects the blue light beam Lb2, thereby reversing the polarization direction of the blue light beam Lb1, which is circularly polarized light (for example, from left circularly polarized light to right circularly polarized light), and deflecting the traveling direction thereof, thereby relay lens 58 is incident.

  The relay lens 58 converts the blue light beam Lb <b> 2 into parallel light and enters the quarter wavelength plate 57. The quarter wavelength plate 52 converts the circularly polarized blue light beam Lb2 into linearly polarized light (for example, right circularly polarized light to s polarized light) and enters the polarizing beam splitter 54 via the LCP 56.

  The polarization beam splitter 54 reflects the blue light beam Lb2 made of s-polarized light by the reflection / transmission surface 54S and makes it incident on the multi lens 58. The multi lens 58 condenses the blue light beam Lb2 and irradiates the photodetector 60 through the pinhole plate 59.

  Here, as shown in FIG. 10, the pinhole plate 59 is disposed so that the focal point of the blue light beam Lb2 collected by the multi-lens 57 (FIG. 9) is located in the hole 59H. The light beam Lb2 is passed as it is.

  On the other hand, as shown in FIG. 10, the pinhole plate 59 has a focal point that is reflected from the surface of the substrate 102 in the optical disc 100, the recording mark RM that exists at a position different from the target mark position, the reflective film 104, and the like. Different light (hereinafter referred to as stray light LN) is substantially blocked. As a result, the photodetector 60 hardly detects the amount of stray light LN.

  As a result, the photodetector 60 generates the detection signal SDb corresponding to the light amount of the blue light beam Lb2 without being affected by the stray light LN, and supplies this to the signal processing unit 23 (FIG. 5). .

  In this case, the reproduction detection signal SDb accurately represents information recorded on the optical disc 100 as the recording mark RM. For this reason, the signal processing unit 23 generates reproduction information by performing predetermined demodulation processing, decoding processing, and the like on the reproduction detection signal SDb, and supplies the reproduction information to the control unit 21.

  As described above, the information optical system 50 receives the blue light beam Lb 2 incident on the objective lens 38 from the optical disc 100 and supplies the light reception result to the signal processing unit 23.

(4) Operation and Effect In the above configuration, the optical pickup 26 of the optical disc apparatus 20 records information as the recording mark RM by being irradiated with the blue light beam Lb1 as the first light having a predetermined intensity or more. A blue light beam Lb1 and a red light beam Lr1 as a second light having a wavelength different from that of the blue light beam Lb1 are condensed and irradiated to the optical disc 100 as an optical information recording medium through the objective lens 40. The objective lens 40 is driven so as to focus the red light beam Lr1 on the reflection layer 104 formed on the optical disc 100 and reflecting at least a part of the red light beam Lr1, thereby changing the convergence state of the blue light beam Lb1. Accordingly, the red color of the red light beam Lr1 in the depth direction in which the objective lens 40 approaches and separates from the optical disk 100. The blue light focus Fb of the blue light beam Lb1 is separated from the light focus Fr by an arbitrary distance, and the blue light focus Fb of the blue light beam Lb1 is adjusted to a target depth to be irradiated with the blue light beam Lb1.

  As a result, the optical pickup 26 can position the blue light focus Fb of the blue light beam Lb1 at the target mark position with respect to the reflective film 104, and forms the recording mark RM at the target mark position of the optical disc 100 to form the optical disc 100. Information can be recorded on the recording layer 101. Here, in the method of forming a recording mark RM made of a hologram by irradiating two light beams from both sides of the conventional optical disc 100, the recording mark RM is formed only at a position where the two light beams match. Therefore, it is difficult to stably form the recording mark RM. On the other hand, in the optical pickup 26, it is only necessary to irradiate one blue light beam Lb1 in accordance with the target mark position of the optical disc 100, so that the recording mark RM can be stably formed and the configuration of the optical pickup 26 is simplified. Can be.

  Further, in the optical pickup 26, the blue light beam Lb1 and the red light beam Lr1 are merged by the light guide unit and guided to the objective lens 40, and the blue light beam Lb2 obtained by reflecting the blue light beam Lb1 by the optical disc 100 is converted into the blue light beam. Returning to the first optical path (mirror 59, relay lens 58, quarter wavelength plate 57, LCP 56, and polarization beam splitter 54) followed by Lb1, the red light beam Lr2 is formed by reflecting the red light beam Lr1 by the reflective film 104. Is returned to the second optical path (¼ wavelength plate 36 and polarization beam splitter 34) followed by the red light beam Lr1, and the first and second separators cause the blue light beam from the first optical path and the second optical path. A photodetector 60 or red light beam that separates Lb2 or red light beam Lr2 and receives blue light beam Lb2. The light Lr2 is guided to the photodetector 43 that receives the light.

  As a result, the optical pickup 26 can cause the blue light beam Lb1 and the blue light beam Lb2 to follow the same first optical path, so that the change in the convergence state caused in the blue light beam Lb1 can be canceled by the return optical path. Therefore, it is not necessary to reflect the change in the convergence state in the blue light beam Lb2 received by the photodetector 60. For this reason, the optical pickup 26 does not need to be provided with an optical component for correcting the change in the convergence state, and the configuration can be simplified.

  Further, the optical pickup 26 uses a dichroic prism 37 that reflects almost all of the red light beam Lr1 and transmits almost all of the blue light beam Lb1 as a light guide, and uses the first light separation unit and the second light separation unit. As a part, polarization beam splitters 34 and 54 for separating a light beam using a difference in polarization direction are used.

  As a result, the optical pickup 26 can irradiate the optical disc 100 with both the blue light beam Lb1 and the red light beam Lr1 through the same objective lens 40, and utilizes the difference in polarization direction to cause the blue light beam Lb1 and the blue light beam to be irradiated. Lb2, the red light beam Lr1 and the red light beam Lr2 can be separated and guided to the photodetectors 60 and 43, and the servo optical system 30 and the information optical system 50 can be configured with a small number of optical components.

  In addition, the optical disk 100 is irradiated with a predetermined initialization light Lp1 on an uncured resin 101A, which is a photoreactive resin containing an organometallic compound, and the uncured resin 101A is cured by a photoreaction to record information. Sometimes, the blue light beam Lb1w, which is the predetermined recording light, is condensed, so that the temperature in the vicinity of the blue light focus Fb of the blue light beam Lb1 rises and the organometallic compound is altered to form a recording mark RM. The recording layer 101 for reproducing the information based on the blue light beam Lb2 corresponding to the irradiation with the predetermined read blue light beam Lb1r during reproduction, and the position of the recording blue light beam Lb1w in the recording layer 101 to an arbitrary position Reflecting at least a part of the red light beam Lr1 that is irradiated for matching and has a wavelength different from that of the recording blue light beam Lb1w. And to have a reflective film 104 is a layer.

  As a result, the optical disc 100 can form the recording mark RM by a simple process of simply irradiating the recording layer 101 with the recording blue light beam Lb1w to the optical disc device 20, and the configuration of the optical disc device 20 can be simplified. Can be.

  According to the above configuration, the optical disc apparatus 20 at least part of the red light beam Lr1 having a wavelength different from that of the blue light beam Lb1 formed on the optical disc 100 that forms the recording mark RM by irradiating the blue light beam Lb1. The objective lens 40 is driven so that the red light beam Lr1 is focused on the reflection film 104 that reflects the light, and the convergence state of the blue light beam Lb1 is changed, whereby the red light is transmitted through the objective lens 40. By irradiating the blue light beam Lb1 at a position different from the red light focal point Fr of the beam Lr1 in the depth direction, the recording mark RM can be formed at an arbitrary target mark position with the reflective film 104 as a reference. Optical pickup, optical information recording apparatus, optical information recording method, and optical information capable of stably recording or reproducing information with a simple configuration Raw device and an optical information reproducing method and an optical information recording medium capable of performing recording or reproduction of stably information can be realized.

(5) Other Embodiments In the above-described embodiment, the present invention is applied to the optical disc apparatus 20 in which the recording mark RM is formed on the recording layer 101 due to the alteration of the organometallic compound. However, the present invention is not limited to this, and a hologram is formed in advance over the entire area of the recording layer 101 whose refractive index changes due to light irradiation, and the hologram is destroyed by irradiation with the blue light beam Lb1. Thus, the present invention may be applied to an optical disc apparatus that forms the recording mark RM.

  In the above-described embodiment, the case where the reflective film 104 is made of a reflective film that reflects almost all of the blue laser light has been described. However, the present invention is not limited to this, and the blue laser light is distributed at a certain ratio. It may be formed as a reflection / transmission film that reflects and transmits (for example, 1: 1). Thereby, even if the optical disk 100 is a case where the board | substrate 102 is damaged, for example, it becomes possible to read information by irradiating the blue light beam Lb1 from the board | substrate 103 side.

  Further, in the above-described embodiment, the case where the reflective film 104 is provided between the substrate 103 on the opposite side of the objective lens 40 and the recording layer 101 has been described, but the present invention is not limited to this, For example, as shown in FIG. 11, the reflective film 104x may be provided between the substrate 102 on the objective lens 40 side and the recording layer 101.

  In this case, the reflective film 104 reflects, for example, 100% of the wavelength light (red laser light) used for servo control of the objective lens 40, while the wavelength light used for recording / reproduction (blue laser light). ), The red light beam Lr2 is reflected to generate the red light beam Lr2, and the blue light beam Lb1 can be irradiated to the target mark position.

  Also, as shown in FIG. 12, two recording layers 101A and 101B may be provided on the optical disc 100X, and a reflective film 104y may be formed on the boundary surface between the recording layers 101A and 101B. At this time, the reflection film 104y is formed as a total reflection film, for example, and the optical disc apparatus 20 has two objective lenses 40x and 40y, and two blue light beams Lb1 are recorded from the two objective lenses 40x and 40y. You may make it irradiate to two target mark positions in 101A and 101B, respectively.

  At this time, the optical disc apparatus 20 uses only one red light beam Lr1, and simultaneously controls the objective lenses 40x and 40y to irradiate two identical blue light beams Lb1 on the same track of the different recording layers 101a and 101b. it can. In the figure, the blue light beam Lb2 is omitted for convenience.

  As a result, the optical disc apparatus 20 can perform two recording processes or reproduction processes in parallel by the two light beams Lb via the two objective lenses 40x and 40y. Speed can be improved.

  Further, the optical disk device 20 controls the objective lenses 40x and 40y independently using two red light beams Lr1 (not shown), for example, two blue lights on different tracks of different recording layers 101a and 101b. Each of the beams Lb1 can be irradiated.

  Further, in this optical disc 100X, the reflective film 104y is formed as a transmissive reflective film 104z (not shown) that reflects about 100% of the red light beam Lr1 and reflects about 50% of the blue light beam Lb1, for example, a substrate. The recording mark RM can be formed on the recording layers 101A and 101B by irradiating the blue light beam Lb1 only from the 102 side.

  In this optical disc 100X, the reflective film 104y is provided at substantially the center of the optical disc 100, and both sides thereof have a symmetrical structure. Therefore, the physical characteristics such as the thermal contraction rate on both sides of the reflective film 104y are centered. They can be matched, and the occurrence of warpage can be suppressed.

  Further, in the above-described embodiment, the case where the optical pickup 26 has the configuration shown in FIG. 6 has been described. However, the present invention is not limited to this, and the arrangement, number, type, and the like of optical components are changed as appropriate. For example, instead of the quarter-wave plates 36 and 57, only one quarter-wave plate may be provided between the modified beam splitter 37 and the objective lens 40, or the servo optical system 30 and information. Instead of the optical system dichroic prism 37, a dichroic prism that transmits the red light beam Lr1 and reflects the blue light beam Lb1 may be used.

  Further, in the above-described embodiment, the case where the recording mark RM is formed on the disc-shaped optical disc 100 has been described. However, the present invention is not limited to this, and for example, optical information recording in a cube shape (cuboid). The recording mark RM may be recorded on the medium.

  Further, in the above-described embodiment, the case where the recording mark is formed by the alteration of the organometallic compound contained in the recording layer 101 has been described. However, the present invention is not limited to this. The recording mark may be formed by raising the temperature to a temperature equal to or higher than the glass transition point of 101 to form a cavity.

  Furthermore, in the above-described embodiment, the optical pickup 26 as the optical pickup is configured by the objective lens 40 as the objective lens, the biaxial actuator 40A as the objective lens driving unit, and the relay lens 58 as the focal point moving unit. Although the present invention has been described, the present invention is not limited to this, and the optical pickup of the present invention may be configured by an objective lens having various configurations, an objective lens driving unit, and a focal point moving unit. good.

  Further, in the above-described embodiment, the optical disk device 20 as the optical information recording device is configured by the objective lens 40 as the objective lens, the biaxial actuator 40A as the objective lens driving unit, and the relay lens 58 as the focus moving unit. Although the present invention is described above, the present invention is not limited to this, and the optical information recording apparatus of the present invention is configured by an objective lens having various configurations, an objective lens driving unit, and a focal point moving unit. You may do it.

  Furthermore, in the above-described embodiment, optical information reproduction is performed by the objective lens 40 as the objective lens, the biaxial actuator 40A as the objective lens driving unit, the relay lens 58 as the focal point moving unit, and the photodetector 60 as the light receiving unit. Although the case where the optical disk device 20 is configured as an apparatus has been described, the present invention is not limited to this, and an objective lens having various other configurations, an objective lens driving unit, a focus moving unit, a light receiving unit, Thus, the optical information reproducing apparatus of the present invention may be configured.

  Further, in the above-described embodiment, the case where the optical disc 100 as the optical information recording medium is configured by the recording layer 101 as the recording layer and the reflective film 104 as the reflective layer has been described. However, the present invention is not limited to this, and the optical information recording medium of the present invention may be configured by a recording layer having various other configurations and a reflective layer.

  The present invention can be used in an optical disc apparatus that records or reproduces a large amount of information such as video content or audio content on a recording medium such as an optical disc.

  DESCRIPTION OF SYMBOLS 20 ... Optical disk apparatus, 21 ... Control part, 26 ... Optical pick-up, 30 ... Servo optical system, 31, 51 ... Laser diode, 34, 54 ... Polarizing beam splitter, 37 ... Dichroic prism, 36, 57 …… ¼ wave plate, 40 …… objective lens, 40A …… biaxial actuator, 43, 60 …… photo detector, 50 …… information optical system, 59 …… pinhole plate, Lb1, Lb2… blue light Beam, Lr1, Lr2 ... red light beam, 100, 100X ... optical disc, 101 ... recording layer, 102, 103 ... substrate, 104 ... reflective film.

Claims (5)

Each of the resins having an organic metal compound and having photoreactivity is cured by a photoreaction caused by irradiation of predetermined initialization light, and the predetermined recording light is condensed when information is recorded. The temperature in the vicinity of the focal point of the recording light rises, the organometallic compound is altered to form a recording mark, and the information is reproduced based on the return light in response to irradiation with a predetermined reading light when reproducing the information. A first recording layer and a second recording layer,
Servo light having a wavelength different from that of the recording light, which is sandwiched between the first and second recording layers and irradiated to adjust the position of the recording light in the first and second recording layers to an arbitrary position. An optical information recording medium comprising: a reflective layer that reflects and reflects and transmits the recording light. The first and second recording layers are
The optical information recording medium according to claim 1, wherein when the initialization light is irradiated, the optical metal is cured by a photoreaction and the organometallic compound is photochemically changed by the initialization light. The optical information recording medium according to claim 1, wherein the first and second recording layers have the same thickness. The reflective layer is
The optical information recording medium according to claim 1, wherein irregularities representing positions in a direction parallel to the reflective layer in the optical information recording medium are formed. The recording layer is
The optical information recording medium according to claim 1, wherein the recording mark is formed by forming a cavity when recording the information.

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