JP2005327396A - Optical pickup and recording and/or reproducing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily correct spherical aberration caused by a thickness error, or the like in a cover layer without being affected by a defocus factor by vibration/impact/temperature change. <P>SOLUTION: There are provided: a light source 31 for emitting a light beam having a prescribed wavelength; an objective lens 32 for condensing the light beam emitted from the light source 31 onto the signal recording surface of an optical disk; an optical element 33 that is provided between the light source 31 and the objective lens 32 and converts the angle of divergence of the light beam emitted from the light source 31; a movement means 40 for correcting the spherical aberration by moving the optical element 33 in the direction of the light axis; a light separation means 34 for partially separating the light beam emitted from the optical element 33 from light beams entering the objective lens 32 while being provided between the optical element 33 and the objective lens 32; and a detector 37 for control for detecting the light beam separated by the light separation means 34. Based on the quantity of light received by the detector 37 for control, the movement means 40 is controlled for controlling the amount of travel in the optical element 33. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup for recording and / or reproducing information on an optical disc on which information is optically recorded and reproduced, such as a magneto-optical disc and a phase change optical disc, and a recording and / or recording using the optical pickup. Or it relates to a playback device.

  Currently, a next-generation optical disc format that uses a blue-violet semiconductor laser light source having a wavelength of about 400 to 410 nm and an objective lens with NA (numerical aperture) = 0.85 is employed. As an optical disk irradiated with laser light having a wavelength of about 400 nm, a structure in which the cover layer protecting the signal recording layer is thin, for example, 0.1 mm has been proposed.

  In such an optical disc, unlike a conventional CD or DVD, since the cover layer is formed extremely thin, a large spherical aberration occurs due to a slight thickness error of the cover layer, which affects the recording / reproducing characteristics. A means for correcting such spherical aberration is required.

  Conventionally, optical pickups corresponding to optical disks having the same outer diameter but different formats such as CD and DVD have been provided. Even in such optical pickups corresponding to optical discs of different formats, spherical aberration occurs due to the difference in the wavelength of the laser light emitted to each optical disc and the thickness of the cover layer of each optical disc, which affects the recording / reproducing characteristics. Therefore, a means for correcting such spherical aberration is required.

  As a means for correcting such spherical aberration, an optical element such as a collimator lens or a beam expander that gives refractive power to the light beam that passes through the optical element that constitutes the optical pickup, and the optical element in the optical axis direction. There is a combination of a driving means for moving the lens and an objective lens (Patent Document 1, Patent Document 2).

  In such an optical pickup, by changing the refractive power of the optical element that gives a refractive power so as to eliminate the spherical aberration due to the thickness error of the cover layer by the driving means that moves the optical element in the optical axis direction, Spherical aberration can be corrected.

  However, this optical pickup has a problem that a defocus component is generated due to a change in the position of the optical element due to vibration, impact, temperature characteristics, and the like, and the correction amount is changed by the defocus component.

  Further, as means for correcting the spherical aberration, a refractive power is given to the light beam that passes through the optical element constituting the optical pickup, that is, an element that converts a divergence angle, for example, a liquid crystal element, and the refractive power of the liquid crystal element. There exists what combined the means to change and an objective lens (patent document 3).

  In such an optical pickup, the spherical aberration is obtained by varying the refractive power of the optical element that gives the refractive power so as to eliminate the spherical aberration caused by the thickness error of the cover layer by means of changing the refractive power of the liquid crystal element. Can be corrected.

  However, this optical pickup has a problem that a defocus component is generated due to a change in the amount of additional phase difference due to temperature characteristics of the liquid crystal element, and a correction amount is changed due to the defocus component.

  In order to prevent such a change in the correction amount, there is an optical pickup that detects the amount of spherical aberration by detecting a shift in the focusing position inside and outside the return light from the disk. Since this optical pickup is premised on the use of return light from the disk, there is a problem that the amount of spherical aberration cannot be detected without focusing.

  In a system in which this optical pickup is susceptible to deterioration of the focus error signal due to a spherical aberration shift such as a next-generation optical disk, focusing for detecting the amount of spherical aberration is difficult. Since the shift of the focal position cannot be detected and stable focusing is difficult, there is a possibility that a significant inconvenience is caused in the system operation. As described above, in a system in which deterioration of the focus error signal is likely to occur, initial adjustment of the spherical aberration amount with respect to the focusing layer is required.

JP-A-9-138343 Japanese Patent Laid-Open No. 5-266511 Japanese Patent Laid-Open No. 8-43345

  An object of the present invention is to stably correct spherical aberration caused by an error in the thickness of a protective substrate without being affected by a defocus component due to vibration, impact, temperature change, etc., and stably perform focusing and recording. An object of the present invention is to provide an optical pickup capable of reproducing and a recording and / or reproducing apparatus using the same.

  To achieve this object, an optical pickup according to the present invention includes a light source that emits a light beam having a predetermined wavelength, an objective lens that focuses the light beam emitted from the light source on a signal recording surface of an optical disc, and a light source. An optical element that is provided between the objective lens and converts the divergence angle of the light beam emitted from the light source, a moving unit that corrects spherical aberration by moving the optical element in the optical axis direction, and the optical element and the objective A light separating means for separating the light beam emitted from the optical element from the light beam incident on the objective lens, and a control detector for detecting the light beam separated by the light separating means; And the moving means is controlled to control the amount of movement of the optical element based on the amount of light received by the control detector.

  An optical pickup according to the present invention includes a light source that emits a light beam having a predetermined wavelength, an objective lens that condenses the light beam emitted from the light source on a signal recording surface of an optical disc, and a space between the light source and the objective lens. And a variable power unit that corrects spherical aberration by varying the refractive power, and is provided between the refractive power variable element and the objective lens, and the light beam emitted from the refractive power variable element is used as the objective lens. A light separation means for partially separating the incident light and a control detector for detecting the light beam separated by the light separation means, and the refraction of the refractive power variable element based on the amount of light received by the control detector. It is characterized by controlling the force.

  In order to achieve the above-described object, a recording and / or reproducing apparatus according to the present invention includes an optical pickup that records and / or reproduces information with respect to an optical disk, and a disk rotation driving unit that rotationally drives the optical disk. The optical pickup is provided between a light source that emits a light beam of a predetermined wavelength, an objective lens that condenses the light beam emitted from the light source on the signal recording surface of the optical disc, and the light source and the objective lens. An optical element that converts the divergence angle of the light beam emitted from the optical element, a moving means that corrects spherical aberration by moving the optical element in the optical axis direction, and an optical element provided between the optical element and the objective lens. A light separation means for partially separating the light beam emitted from the light beam incident on the objective lens, and a control detector for detecting the light beam separated by the light separation means, Comprising, based on the amount of light received by the control detector, and controlling the amount of movement of the optical element by controlling the moving means.

  A recording and / or reproducing apparatus according to the present invention includes an optical pickup that records and / or reproduces information with respect to an optical disk, and a disk rotation driving unit that rotationally drives the optical disk. A spherical light source is corrected by varying the refractive power provided between the light source that emits the beam, the objective lens that focuses the light beam emitted from the light source on the signal recording surface of the optical disc, and the light source and the objective lens. A refractive power variable element, a light separation means that is provided between the refractive power variable element and the objective lens and that partially separates the light beam emitted from the refractive power variable element from the light incident on the objective lens, and the light separation means And a control detector for detecting the light beam separated by the control detector, and controlling the refractive power of the refractive power variable element based on the amount of light received by the control detector. .

  According to the present invention, the light beam before being incident on the optical disk is received by the control detector after the divergence angle is converted by the light separation means provided between the optical element for converting the divergence angle and the objective lens. Since the moving means is controlled based on the amount of light that is generated, it is possible to prevent deterioration of spot quality due to vibration, shock, temperature change, etc., and to correct spherical aberration due to errors in the protective substrate thickness of the optical disk, etc., and a stable focusing signal As a result, a good recording / reproducing operation is possible.

  According to the present invention, the light separation means provided between the refractive power variable element that changes the refractive power and the objective lens detects the light beam before passing through the refractive power variable element and entering the optical disk for control. Since the refractive power of the variable power element is controlled based on the amount of light received by the detector, it prevents the deterioration of the spot quality due to temperature changes, etc., and can correct spherical aberrations due to errors in the protective substrate thickness of the optical disk, etc. Thus, a good focusing / reproducing operation can be performed.

  Hereinafter, a recording / reproducing apparatus using an optical pickup to which the present invention is applied will be described with reference to the drawings.

  As shown in FIG. 1, a recording / reproducing apparatus 1 to which the present invention is applied includes an optical pickup 3 for recording / reproducing information from / on an optical disc 2, a spindle motor 4 as a driving means for rotating the optical disc 2, and an optical pickup 3 And a feed motor 5 for moving the optical disk 2 in the radial direction of the optical disk 2.

  The recording / reproducing apparatus 1 can, for example, rewrite information such as a CD (Compact Disc), a DVD (Digital Versatile Disc), a CD-R (Recordable) and a DVD-R (Recordable) in which information can be additionally written. CD-RW (ReWritable), DVD-RW (ReWritable), DVD + RW (ReWritable), etc., an optical disc capable of high-density recording using a semiconductor laser having a shorter emission wavelength of about 405 nm (blue-violet), Information can be recorded on and / or reproduced from the optical disk 2 such as a magneto-optical disk (hereinafter referred to as recording / reproduction).

  In the recording / reproducing apparatus 1, the spindle motor 4 and the feed motor 5 are driven and controlled in accordance with the disc type by a servo control unit 9 controlled based on a command from the system controller 7 which also serves as a disc type discriminating means. Driven by number. The optical pickup 3 irradiates a light beam having a predetermined wavelength and detects reflected light from the recording layer of the light beam. The optical pickup 3 supplies a signal corresponding to each light beam from the detected reflected light to the preamplifier unit 14.

  The output of the preamplifier unit 14 is sent to a signal modulator / demodulator and an error correction code block (hereinafter referred to as a signal modulation / demodulation & ECC block) 15. The signal modulation / demodulation and ECC block 15 performs signal modulation, demodulation, and addition of ECC (error correction code). The optical pickup 3 irradiates the recording layer of the optical disc 2 rotating according to the signal modulation / demodulation and the command of the ECC block 15, and records or reproduces the signal on the optical disc 2.

  The preamplifier unit 14 is configured to generate a focus error signal, a tracking error signal, an RF signal, and the like based on a signal corresponding to a light beam detected differently for each format. In accordance with the type of the optical disk 2 to be recorded or reproduced, predetermined processing such as demodulation and error correction processing based on the standard of the optical disk 2 is performed by the servo control circuit 9, the signal modulation / demodulation, the ECC block 15, and the like. .

  Here, for example, if the recording signal demodulated by the signal modulation / demodulation & ECC block 15 is for data storage of a computer, it is sent to the external computer 17 via the interface 16. Thereby, the external computer 17 etc. can receive the signal recorded on the optical disk 2 as a reproduction signal.

  Further, if the recording signal demodulated by the signal modulation / demodulation & ECC block 15 is for audio visual, it is digital / analog converted by the D / A converter of the D / A and A / D converter 18 and supplied to the audio visual processor 19. Is done. Audio visual processing is performed by the audio visual processing unit 19 and transmitted to an external imaging / projection device (not shown) or the like via the audio visual signal input / output unit 20.

  In the optical pickup 3, for example, control of the feed motor 5 for moving to a predetermined recording track on the optical disk 2, control of the spindle motor 4, and two axes for holding an objective lens serving as light condensing means in the optical pickup 3 The servo control circuit 9 controls driving of the actuator in the focusing direction and driving control in the tracking direction.

  The laser control unit 21 controls the laser light source of the optical pickup 3. In particular, in this specific example, the laser control unit 21 performs control to vary the output power of the laser light source between the recording mode and the reproduction mode. Also, control is performed to vary the output power of the laser light source depending on the type of the optical disc 2. The laser control unit 21 switches the laser light source of the optical pickup 3 in accordance with the type of the optical disc 2 detected by the disc type determination unit 22.

  The disc type discriminating unit 22 can detect different formats of the optical disc 2 from the surface reflectance between different optical discs, differences in shape and shape, and the like.

  Each block constituting the recording / reproducing apparatus 1 is configured to be able to perform signal processing based on the specification of the optical disk to be mounted, according to the detection result in the disk type discriminating unit 22.

  The system controller 7 determines the type of the optical disk 2 based on the detection result sent from the disk type determination unit 22. As a method for discriminating the type of the optical disc, if the optical disc is of a type that is housed in a cartridge, there is a method in which a detection hole is provided in the cartridge and detected using a contact detection sensor or a push switch. In addition, the recording layer in the same optical disc is discriminated with respect to which recording layer is recorded / reproduced based on information by table information (TOC) recorded in premastered pits and grooves in the innermost circumference of the optical disc. Can be used.

  The servo control circuit 9 is controlled by the system controller 7 and controls the focal length in the optical pickup 3, that is, the position of a collimator lens 33 to be described later, according to the determination result of the disk type determination unit 22. The servo control circuit 9 performs recording and / or reproduction by, for example, detecting the relative position between the optical pickup 3 and the optical disk 2 (including the case of detecting the position based on the address signal recorded on the optical disk 2). The area can be determined.

  In the recording / reproducing apparatus 1 configured as described above, the optical disk 2 is rotated by the spindle motor 4, the feed motor 5 is driven and controlled according to the control signal from the servo controller 9, and the optical pickup 3 is moved to the optical disk 2. By moving to a position corresponding to the desired recording track, information is recorded on and reproduced from the optical disc 2.

  Here, the recording / reproducing optical pickup 3 described above will be described in detail.

  As shown in FIG. 2, an optical pickup 3 to which the present invention is applied includes a light source unit 31 that emits a light beam having a predetermined wavelength, and a light beam emitted from the light source unit 31 on a signal recording surface 2a of the optical disc 2. A collimator lens 33 as an optical element that converts the divergence angle of the incident light beam provided between the light source unit 31 and the objective lens 32, and between the collimator lens 33 and the objective lens 32. A first beam splitter 34 for partially separating the light beam emitted from the collimator lens 33 from the light beam incident on the objective lens 32, and provided between the light source unit 31 and the collimator lens 33. A second beam splitter 35 for branching the optical path of the reflected return light from the optical path of the outgoing light, and a return branch branched by the second beam splitter 35 And an optical detector 36 for detecting light.

  The collimator lens 33 is provided with an actuator 40 that moves the collimator lens 33 in the optical axis direction. The collimator lens 33 is moved in the optical axis direction by the actuator 40, so that the power aberration of the light beam after passing through the collimator lens 33 can be generated, that is, the divergence angle of the passed light beam can be changed.

  The collimator lens 33 can correct the spherical aberration due to the error of the protective substrate thickness 2a of the optical disk 2 by the change of the divergence angle, and the vibration, impact, temperature by the defocus component accompanying the change of the divergence angle. The shift of the focal position due to a change or the like can be corrected. Here, the defocus component is a component that generates a focus shift, and a focal position at a predetermined divergence angle before the change by changing the divergence angle of the light beam incident on the objective lens 32. Is the amount of deviation of the focal position of the light beam after the change.

  On the incident side of the objective lens 32, a first aperture filter 41 is provided as an aperture limiting element that limits the aperture of the light beam incident on the objective lens 32. The objective lens 32 can focus the light beam, whose divergence angle is converted by the collimator lens 33 and whose aperture is limited by the first aperture filter 41, on the signal recording surface 2 a of the optical disc 2.

  Further, the optical pickup 3 is provided between the first beam splitter 34 and the control detection unit 37, and is provided between the control detection unit 37 for detecting the light beam separated by the first beam splitter 34. An optical element 38 that focuses the light beam separated by one beam splitter 34 on the light receiving surface of the control detector 37, and a second aperture filter 42 provided on the incident side of the optical element 38 are provided.

  The control detector 37 can detect the defocus component by detecting the light amount of the light beam that has passed through the collimator lens 33. That is, in order to properly collect the light beam on the signal recording surface 2a of the optical disc 2, the divergence angle of the light beam incident on the objective lens 32 needs to be a predetermined angle. The light beam that has passed through the collimator lens 33 has a predetermined divergence angle under appropriate conditions, and is focused on the signal recording surface 2 a of the optical disc 2 by the objective lens 32. However, for example, when a position shift due to vibration / impact and a change in refractive power of the collimator lens 33 due to a temperature change occur, the light beam that has passed through the collimator lens 33 has a divergence angle compared to a predetermined angle. Will be changed. Along with this change in the divergence angle, there arises a problem that the signal recording surface 2a cannot be properly condensed.

  Under the appropriate conditions, the control detector 37 passes through the collimator lens 33 and is partially separated by the first beam splitter 34 and is appropriately condensed by the optical element 38. Is done. However, the light beam whose divergence angle is changed by passing through the collimator lens 33 due to the vibration, shock, and temperature change described above is partly separated by the first beam splitter 34 and is appropriately placed on the control detector 37. Deviation occurs without condensing light. Therefore, the control detector 37 can detect the defocus component of the light beam that has passed through the collimator lens 33, that is, the divergence angle, by detecting the deviation of the in-focus position between the inner peripheral portion and the outer peripheral portion. it can. More specifically, when the collimator lens 33 moves toward the objective lens 32 with respect to an appropriate position where the passing light beam is set at a predetermined angle, the light transmitted through the first beam splitter 34 is transmitted. The focal position shifts in front of the signal recording surface 2a. At this time, the control detector 37 can detect the defocus component by detecting the shift amount of the light beam partially separated by the first beam splitter 34. In addition, when the collimator lens 33 moves to the light source side with respect to an appropriate position where the passing light beam has a predetermined angle, the light that has passed through the first beam splitter is the signal recording surface of the optical disc 2. The focal position shifts to a position farther than 2a. At this time, the control detector 37 can detect the defocus component by detecting the shift amount of the light beam partially separated by the first beam splitter 34.

  The optical pickup 3 detects the occurrence of a defocus component based on the detection signal detected by the control detector 37, and generates an aberration correction circuit 44 that generates an aberration correction signal associated with the generation of the defocus component. An actuator driving circuit 45 that receives the aberration correction signal generated by the correction circuit 44 and drives the actuator 40.

  The actuator drive circuit 45 optimizes the collimator lens 33 based on the aberration correction signal generated by the aberration correction circuit 44 that detects the defocus component of the light beam detected by the control detector 37, that is, the deviation of the divergence angle. The position is moved to a position where the divergence angle of the light beam becomes a predetermined angle, and the deviation of the divergence angle and the shift of the focal position associated therewith are moved to zero.

  The optical pickup 3 detects the occurrence of spherical aberration due to an error in the thickness of the protective substrate of the optical disk from the detection signal detected by the photodetector 36, and generates an aberration correction signal and an actuator drive. The actuator 45 is driven by the circuit 45 to move the collimator lens 33 to a position where the spherical aberration becomes zero.

  Next, the optical path of the laser light emitted from the light source unit in the optical pickup 3 will be described.

  The light beam emitted from the light source unit 31 is converted into a divergence angle by the collimator lens 33 and emitted to the objective lens 32 side. A part of the light beam whose divergence angle is converted by the collimator lens 33 is separated by the first beam splitter 34 to the control detector 37 side. The light beam separated by the first beam splitter 34 is aperture-limited by the second aperture filter 42, and is condensed on the control detector 37 by the optical element 38.

  The control detector 37 detects the laser beam separated from the light beam incident on the objective lens 32, and detects the defocus component of the laser beam, that is, the deviation of the divergence angle of the light beam from a predetermined angle. . The actuator drive circuit 45 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the control detector 37 and drives the actuator 40. The actuator 40 moves the collimator lens 33 so that the defocus component becomes an appropriate value, that is, the light beam is appropriately condensed on the signal recording surface 2a of the optical disc 2.

  Most of the light beam having a predetermined appropriate divergence angle by the movement of the collimator lens 33 is transmitted through the first beam splitter 34, the aperture is limited by the first aperture filter 41, and the optical disk is controlled by the objective lens 32. 2 is condensed on the signal recording surface 2a.

  The light beam condensed on the signal recording surface 2a of the optical disc 2 is reflected by the signal recording surface 2a, passes through the objective lens 32 and the first beam splitter 34, is converged by the collimator lens 44, and is secondly reflected. The optical path is branched from the incident light by the beam splitter 35 and detected by the photodetector 36.

  The actuator drive circuit 45 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the photodetector 36 and drives the actuator 40. The actuator 40 moves the collimator lens 33 so that the spherical aberration due to the error of the protective substrate thickness of the optical disc 2 becomes zero.

  The optical pickup 3 to which the present invention is applied separates the light beam before being focused on the optical disk by the first beam splitter, and detects the defocus component, that is, the divergence state of this light beam by the control detector. Because the detection signal moves the collimator lens so that the light beam is properly focused on the signal recording surface, for example, when the divergence angle of the light beam that has passed through the collimator lens changes due to vibration, impact, temperature change, etc. In addition, the control detector detects the divergence state of the light beam that has passed through the collimator lens, and the light beam is appropriately applied to the signal recording surface of the optical disc by adjusting the divergence angle of the light beam by moving the collimator lens. It can be condensed. Furthermore, by detecting the return light from the optical disk with a photodetector and moving the collimator lens, spherical aberration due to an error in the protective substrate thickness of the optical disk can be corrected well, and a stable focusing signal can be obtained. it can.

  That is, the optical pickup 3 to which the present invention is applied is used, for example, for an optical disc capable of high-density recording using a light beam having a protective substrate thickness of 0.1 mm and a wavelength of about 405 nm as recording / reproducing light. However, it is possible to prevent the occurrence of defects in the correction of spherical aberration due to a decrease in spot quality on the signal recording surface. As described above, the optical pickup 3 to which the present invention is applied improves the spot quality of the optical disk by the control detector and corrects the spherical aberration due to the error of the protective substrate thickness by the photodetector, so that a stable focusing signal is generated. As a result, a good recording / reproducing operation is possible.

  In the optical pickup 3, the collimator lens 33 is used as an optical element for converting the divergence angle. However, the present invention is not limited to this, and for example, a beam expander or the like may be used.

  Next, the optical pickup 50 shown in FIG. 3 using a beam expander as an optical element for converting the divergence angle will be described. In the following description, portions common to the optical pickup 3 described above are denoted by common reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, an optical pickup 50 to which the present invention is applied includes a light source unit 31 that emits a light beam having a predetermined wavelength, and a light beam emitted from the light source unit 31 on a signal recording surface 2a of the optical disc 2. A beam expander 53, a beam expander 53, and an objective lens 32 as optical elements that are provided between the light source unit 31 and the objective lens 32 and convert the divergence angle of the incident light beam. Between the light source unit 31 and the beam expander 53, and a first beam splitter 34 that partially separates the light beam emitted from the beam expander 53 from the light beam incident on the objective lens 32. The second beam splitter 35 and the second beam splitter 35 divide the optical path of the return light reflected by the optical disc from the optical path of the outgoing light. And an optical detector 36 for detecting the return light.

  The beam expander 53 includes a first lens 54 having a negative refractive power, a second lens 55 having a positive refractive power, and a lens holding unit that holds the first lens 54 and the second lens 55. It consists of a body 56.

  The beam expander 53 is provided with an actuator 57 that moves the beam expander 53 in the optical axis direction. The beam expander 53 is moved in the optical axis direction by the actuator 57 to generate power aberration of the light beam after passing through the beam expander 53, that is, to change the divergence angle of the passed light beam. it can.

  The beam expander 53 can correct the spherical aberration due to the error of the protective substrate thickness of the optical disk 2 by the change in the divergence angle, and the vibration, impact, temperature by the defocus component accompanying the change in the divergence angle. The shift of the focal position due to a change or the like can be corrected.

  Further, in the optical pickup 50, as in the optical pickup 3 described above, a control detector 37 that detects the light beam separated by the first beam splitter 34, and the first beam splitter 34 and the control detector 37, an optical element 38 for focusing the light beam separated by the first beam splitter 34 on the light receiving surface of the control detector 37, and a second aperture provided on the incident side of the optical element 38. A filter 42 is provided.

  In the control detector 37, the light beam which has passed through the beam expander 53 and has a predetermined angle under appropriate conditions is partly separated by the first beam splitter 34 and appropriately collected by the optical element 38. Lighted. However, the light beam whose divergence angle has been changed by passing through the beam expander 53 due to vibration, impact, or temperature change is partly separated by the first beam splitter 34 and is appropriately placed on the control detector 37. Deviation occurs without focusing. The control detector 37 can detect the defocus component of the light beam that has passed through the beam expander 53, that is, the divergence angle, by detecting the shift of the in-focus position between the inner peripheral portion and the outer peripheral portion. .

  Similar to the optical pickup 3 described above, the optical pickup 50 detects the occurrence of a defocus component based on the detection signal detected by the control detector 37, and outputs a signal for correcting the aberration associated with the occurrence of the defocus component. An aberration correction circuit 44 to be generated and an actuator drive circuit 45 that receives the aberration correction signal generated by the aberration correction circuit 44 and drives the actuator 57 are provided. The actuator drive circuit 45 uses the aberration correction signal generated by the aberration correction circuit 44 that detects the defocus component of the light beam detected by the control detector 37, that is, the deviation of the divergence angle, to the beam expander 53. The position is moved to an optimum position, that is, a position where the divergence angle of the light beam becomes a predetermined angle, and moved to a position where the deviation of the divergence angle and the deviation of the focal position associated therewith become zero.

  The optical pickup 50 detects the occurrence of spherical aberration due to an error in the thickness of the protective substrate of the optical disk from the detection signal detected by the photodetector 36, and generates an aberration correction signal and an actuator drive. The circuit 45 drives the actuator 57 to move the beam expander 53 to a position where the spherical aberration becomes zero.

  Next, the optical path of the laser light emitted from the light source unit in the optical pickup 50 will be described.

  The light beam emitted from the light source unit 31 is converted into a divergence angle by the first lens 54 and the second lens 55 of the beam expander 53 and emitted to the objective lens 32 side. A part of the light beam whose divergence angle is converted by the beam expander 53 is separated by the first beam splitter 34 toward the control detector 37. The light beam separated by the first beam splitter 34 is aperture-limited by the second aperture filter 42, and is condensed on the control detector 37 by the optical element 38.

  The control detector 37 detects the laser beam separated from the light beam incident on the objective lens 32, and detects the defocus component of the laser beam, that is, the deviation of the divergence angle of the light beam from a predetermined angle. . The actuator drive circuit 45 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the control detector 37 and drives the actuator 57. The actuator 57 moves the beam expander 53 so that the defocus component becomes an appropriate value, that is, the light beam is appropriately condensed on the signal recording surface of the optical disc 2.

  Most of the light beam having a predetermined appropriate divergence angle due to the movement of the beam expander 53 is transmitted through the first beam splitter 34, the aperture is limited by the first aperture filter 41, and the objective lens 32 The light is focused on the signal recording surface 2 a of the optical disc 2.

  The light beam condensed on the signal recording surface 2a of the optical disc 2 is reflected by the signal recording surface 2a, passes through the objective lens 32 and the first beam splitter 34, is converged by the beam expander 53, and is second. The optical path is branched from the incident light by the beam splitter 35 and is detected by the photodetector 36.

  The actuator drive circuit 45 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the photodetector 36 and drives the actuator 57. The actuator 57 moves the beam expander 53 so that the spherical aberration due to the error of the protective substrate thickness of the optical disc 2 becomes zero.

  The optical pickup 50 to which the present invention is applied separates the light beam before being focused on the optical disk by the first beam splitter, and detects the defocus component, that is, the divergence state of the light beam by the control detector. The beam expander is moved by this detection signal so that the light beam is properly focused on the signal recording surface. For example, the divergence angle of the light beam that has passed through the beam expander changes due to vibration, impact, temperature change, etc. In this case, the control detector detects the divergence state of the light beam that has passed through the beam expander, and the light beam divergence angle is adjusted appropriately by moving the beam expander. The light beam can be condensed. Furthermore, by detecting the return light from the optical disc with a photodetector and moving the beam expander, spherical aberration due to the error of the protective substrate thickness of the optical disc can be corrected well, and a stable focusing signal can be obtained. Can do.

  That is, the optical pickup 50 to which the present invention is applied is used, for example, in an optical disc capable of high-density recording using a light beam having a protective substrate thickness of 0.1 mm and a wavelength of about 405 nm as recording / reproducing light. However, it is possible to prevent the occurrence of defects in the correction of spherical aberration due to a decrease in spot quality on the signal recording surface. As described above, the optical pickup 50 to which the present invention is applied improves the spot quality of the optical disc by the control detector and corrects the spherical aberration due to the error of the protective substrate thickness by the photodetector, so that a stable focusing signal is generated. As a result, a good recording / reproducing operation is possible.

  The beam expander 53 described above has a first lens having a negative refractive power and a second lens having a positive refractive power, and the entire beam expander is driven by an actuator. However, the present invention is not limited to this, and it is only necessary to have one or more lenses each having positive and negative refractive powers, and the divergence angle of the light beam passing through the one or more lenses driven by an actuator is converted. What is necessary is just to comprise.

  In addition, the optical pickup 3 and the optical pickup 50 are configured to include the optical element that converts the divergence angle and the actuator that is the moving means. However, the present invention is not limited to this, and for example, the refractive power that can change the refractive power. You may comprise so that a variable element may be provided.

  Next, an optical pickup 60 shown in FIG. 4 using a refractive power variable element will be described. In the following description, portions common to the optical pickup 3 described above are denoted by common reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, an optical pickup 60 to which the present invention is applied includes a light source unit 31 that emits a light beam having a predetermined wavelength, and a light beam emitted from the light source unit 31 on the signal recording surface 2a of the optical disc 2. An objective lens 32 that collects light, a refractive power variable element 63 that is provided between the light source unit 31 and the objective lens 32, and that changes the refractive power of the incident light beam, and the refractive power variable element 63 and the objective lens 32. A first beam splitter 34 provided between the light source unit 31 and the refractive power variable element 63, which partially separates a light beam emitted from the refractive power variable element 63 from a light beam incident on the objective lens 32. A second beam splitter 35 provided for branching the optical path of the return light reflected by the optical disc from the optical path of the outgoing light, and light detection for detecting the return light branched by the second beam splitter 35 And a 36..

  The refractive power variable element 63 corrects the spherical aberration by changing the refractive power, and a liquid crystal optical element is used. The refractive power variable element 63 is formed by sandwiching liquid crystal molecules between two glass substrates on which transparent electrodes are formed. When a driving voltage is applied to each transparent electrode, the orientation of the liquid crystal molecules is deviated in accordance with the electric field generated by the applied voltage, thereby arbitrarily changing the refractive index of the laser light transmitted through the refractive power variable element 63. That is, the refractive power variable element 63 can convert the divergence angle of the transmitted laser light, and can change the divergence angle conversion amount and power aberration arbitrarily by changing the refractive index.

  The refracting power variable element 63 can correct spherical aberration due to an error in the protective substrate thickness of the optical disk 2 and the like by this change in the divergence angle, and correct a focal position shift due to vibration, impact, temperature change, and the like. Can do.

  The optical pickup 60 includes a control detection unit 37 that detects the light beam separated by the first beam splitter 34, and the first beam splitter 34 and the control detection unit, as in the optical pickup 3 described above. 37, an optical element 38 for focusing the light beam separated by the first beam splitter 34 on the light receiving surface of the control detector 37, and a second aperture provided on the incident side of the optical element 38. A filter 42 is provided.

  The control detector 37 can detect the defocus component by detecting the light amount of the light beam that has passed through the refractive power variable element 63. In this control detector 37, the light beam having passed through the refractive power variable element 63 and having a predetermined angle under a suitable condition is partly separated by the first beam splitter 34, and is appropriately applied by the optical element 38. It is focused on. However, the light beam whose divergence angle is changed after passing through the refractive power variable element 63 due to temperature change or the like is partly separated by the first beam splitter 34 and is appropriately condensed on the control detector 37. Deviation occurs without. The control detector 37 detects the defocus component of the light beam that has passed through the refractive power variable element 63, that is, the divergence angle, by detecting the deviation of the in-focus position between the inner and outer peripheral portions. it can.

  Similar to the optical pickup 3, the optical pickup 60 detects the occurrence of a defocus component from the detection signal detected by the control detector 37, and generates an aberration correction signal associated with the defocus component. A circuit 44 and a refractive power variable element control circuit 64 which receives the aberration correction signal generated by the aberration correction circuit 44 and controls a voltage applied to the refractive power variable element 63 are provided. The refractive power variable element 63 receives the aberration correction signal generated by the aberration correction circuit 44 that detects the focus component of the light beam detected by the control detector 37, that is, the deviation of the divergence angle. The voltage applied to the transparent electrode of the glass substrate is controlled by the control circuit 64, and the refractive index is varied so that the deviation of the divergence angle and the deviation of the focal position associated therewith become zero.

  Further, the optical pickup 60 detects the occurrence of spherical aberration due to an error in the thickness of the protective substrate of the optical disk from the detection signal detected by the photodetector 36, and generates an aberration correction signal and an aberration correction circuit 44. The variable element control circuit 64 controls the voltage applied to the transparent electrode of the glass substrate and varies the refractive index of the refractive power variable element 63 so that the spherical aberration becomes zero.

  Next, the optical path of the laser light emitted from the light source unit in the optical pickup 60 will be described.

  The light beam emitted from the light source unit 31 is refracted by the refractive power variable element 63, the divergence angle is converted, and emitted to the objective lens 32 side. A part of the light beam whose divergence angle is converted by the refractive power variable element 63 is separated by the first beam splitter 34 to the control detector 37 side. The light beam separated by the first beam splitter 34 is aperture-limited by the second aperture filter 42, and is condensed on the control detector 37 by the optical element 38.

  The control detector 37 detects the laser beam separated from the light beam incident on the objective lens 32, and detects the defocus component of the laser beam, that is, the deviation of the divergence angle of the light beam from a predetermined angle. . The refractive power variable element control circuit 64 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the control detector 37, and the divergence angle as a defocus component becomes an appropriate value. That is, the refractive power of the variable refractive power element 63 is changed so that the light beam is appropriately focused on the signal recording surface of the optical disc 2.

  Most of the light beam having an appropriate divergence angle by the refractive power variable element 63 whose refractive power has been changed passes through the first beam splitter 34 and is limited in aperture by the first aperture filter 41. 32, the light is condensed on the signal recording surface 2 a of the optical disc 2.

  The light beam condensed on the signal recording surface 2a of the optical disc 2 is reflected by the signal recording surface 2a, passes through the objective lens 32 and the first beam splitter 34, is converged by the refractive power variable element 63, and The optical path is branched from the incident light by the two beam splitters 35 and detected by the photodetector 36.

  The refractive power variable element control circuit 64 receives the aberration correction signal generated by the aberration correction circuit 44 based on the detection signal detected by the photodetector 36 and changes the refractive power of the refractive power variable element 63.

  An optical pickup 60 to which the present invention is applied separates a light beam before being focused on an optical disk by a first beam splitter, and this light beam is detected by a control photodetector to detect a defocused component, that is, a divergent state. The refracting power of the refracting power variable element is changed by this detection signal so that the light beam is properly focused on the signal recording surface. Even when the value changes, the divergence state of the light beam refracted by the variable power element is detected by the control detector, and the refractive power of the variable power element is changed to appropriately adjust the divergence angle of the light beam. Thus, the light beam can be appropriately focused on the signal recording surface of the optical disc. Furthermore, by detecting the return light from the optical disk with a photodetector and changing the refractive power of the variable refractive power element, spherical aberration due to errors in the protective substrate thickness of the optical disk can be corrected well, and a stable focusing signal can be obtained. Can be obtained.

  That is, the optical pickup 60 to which the present invention is applied is used, for example, in an optical disc capable of high-density recording using a light beam having a protective substrate thickness of 0.1 mm and a wavelength of about 405 nm as recording / reproducing light. However, it is possible to prevent the occurrence of defects in the correction of spherical aberration due to a decrease in spot quality on the signal recording surface. As described above, the optical pickup 60 to which the present invention is applied improves the spot quality of the optical disc by the control detector and corrects the spherical aberration due to the error of the protective substrate thickness by the photodetector, so that a stable focusing signal is generated. As a result, a good recording / reproducing operation is possible.

  In the above-described optical pickup 3, optical pickup 50, and optical pickup 60, the control detector 37 can be used as a FAPC (Front Auto Power Control).

  For example, in the optical pickup 3, when the control detector 37 is used as FAPC, a filter equivalent to the first aperture filter 41 is used as the second aperture filter 42. This optical pickup functions as this FAPC even if the defocus component, that is, the divergence angle of the light beam changes due to the movement of the collimator lens 33 and the amount of light beam passing through the first aperture filter 41 changes. By changing the output power of the light source unit 31 according to the detection signal of the control detector 37, it is possible to prevent a change in the amount of light at the signal recording surface 2a of the disk 2 and the photodetector 36.

  In the optical pickup 3, the optical pickup 50, and the optical pickup 60 described above, the control detector 37 detects a noise component of the light beam emitted from the light source unit 31 and is detected by the photodetector 36. You may comprise so that a noise component may be canceled from a signal. The optical pickup configured to detect the laser noise component by the control detector 37 can remove the laser noise component and obtain a good recording / reproducing signal.

  Further, in the optical pickup 3, the optical pickup 50, and the optical pickup 60 described above, the light source unit has been described as emitting a light beam of one type of wavelength, but 2 that emits light beams of two or three different types of wavelengths. Alternatively, a two-wavelength compatible and three-wavelength compatible optical pickup including a light source unit having three emission units may be used. In this case, the first aperture filter 41 and the objective lens 32 having compatibility according to the wavelength are used. In this optical pickup, a defocus component is detected and adjusted by a collimator lens 33 and a control detector 37, and a light beam is appropriately focused on a signal recording surface even for a plurality of types of optical disks having different protective substrate thicknesses. Thereafter, the spherical aberration can be favorably corrected by the detection signal of the photodetector 36.

  In addition, among the optical systems of the optical pickup 3, the optical pickup 50, and the optical pickup 60 described above, the same or different optical systems may be combined to share the control detector and the objective lens. .

  Next, a description will be given of the optical pickup 70 shown in FIG. 5 in which a light source and an optical element for converting a divergence angle are added to the optical pickup 3 so as to correspond to a plurality of types of optical disks. In the following description, portions common to the optical pickup 3 described above are denoted by common reference numerals, and detailed description thereof is omitted.

  The optical pickup 70 to which the present invention is applied includes a first optical disk 11 capable of high-density recording using a light beam having a protective substrate thickness of 0.1 mm and a wavelength of about 405 nm as recording / reproducing light, and a protective substrate thickness of 0.1 mm. A second optical disk 12 such as a DVD that uses a light beam having a wavelength of about 655 nm as recording / reproducing light at 6 mm, and a CD that uses a light beam having a protective substrate thickness of 1.2 mm and a wavelength of about 785 nm as recording / reproducing light. Recording / reproducing of signals on the third optical disc 13.

  As shown in FIG. 5, the optical pickup 70 includes a first light source unit 71 having a first emission unit that emits a light beam having a first wavelength of about 405 nm, and a second wavelength of about 655 nm. A second light source part 72 having a second emission part for emitting a light beam and a third emission part for emitting a light beam of a third wavelength of about 785 nm; the first light source part 71 and the first light source part 71; An objective lens 73 for condensing the light beam emitted from the second light source 72 on the signal recording surface 2a of the optical disc 2, and the incident light beam provided between the first light source 71 and the objective lens 72. As an optical element that converts the divergence angle of the first light beam, the second collimator lens 74 is provided between the second light source 72 and the objective lens 72, and the second optical element that converts the divergence angle of the incident light beam. A collimator lens 75 and a first Provided between the collimator lens 74 and the objective lens 73, the light beam emitted from the first collimator lens 74 is partly separated from the light beam incident on the objective lens 73 and emitted from the second collimator lens 74. The first light splitter 76 that partially separates the obtained light beam from the light beam incident on the objective lens 72, the first light source unit 71, and the first collimator lens 74 are provided and reflected by the optical disc 2. Provided between the second beam splitter 77 for branching the optical path of the return light from the optical path of the outgoing light, the second light source 72, and the second collimator lens 75, and the optical path of the return light reflected by the optical disc A third beam splitter 78 branched from the optical path of the emitted light, and a first optical detector for detecting return light branched by the second beam splitter 77. A vessel 81, and a second photodetector 82 for detecting the return light split by the third beam splitter 78.

  The first collimator lens 74 and the second collimator lens 75 have the same function as that of the collimator lens 33 constituting the optical pickup 3 described above. The first collimator lens 74 and the second collimator lens 75 are connected to the optical axis, respectively. A first actuator 83 and a second actuator 84 that move in the direction are provided. The first and second collimator lenses 74 and 75 are moved in the optical axis direction by the first and second actuators 83 and 84, so that the light after passing through the first and second collimator lenses 74 and 75. The divergence angle of the beam can be changed.

On the incident side of the objective lens 73, a first aperture filter 85 is provided as an aperture limiting element that limits the aperture of the light beam incident on the objective lens 73. The first aperture filter 85 has a wavelength dependency in which the aperture diameter changes depending on the wavelength, and is 0.85 for the first wavelength and 0.60 for the second wavelength. It is set to 0.45 with respect to the 3rd wavelength, for example, consists of a hologram etc. The objective lens 73 collects the light beam whose divergence angle is converted by the first or second collimator lenses 74 and 75 and whose aperture is limited by the first aperture filter 85 on the signal recording surface 2 a of the optical disc 2. it can.
The optical pickup 70 is provided between a control detector 88 that detects the light beam separated by the first beam splitter 76, and between the first beam splitter 76 and the control detector 88. An optical element 87 for focusing the light beam separated by one beam splitter 76 on the light receiving surface of the control detector 88 and a second aperture filter 86 provided on the incident side of the optical element 87 are provided.

  The control detector 88 has the same function as the control detector 37 described above, and detects the defocus component by detecting the light amount of the light beam that has passed through the first or second collimator lens 74 or 75. can do. The control detector 88 detects a focus shift of the partially separated light beam by the first beam splitter 76, so that the focus component of the light beam that has passed through the first or second collimator lens 74 or 75. That is, the divergence angle can be detected.

  The optical pickup 70 detects the occurrence of a defocus component based on the detection signal detected by the control detector 88, and generates an aberration correction circuit 90 that generates a signal for correcting an aberration associated with the generation of the defocus component. An actuator drive circuit 91 that receives the aberration correction signal generated by the correction circuit 90 and drives the first or second actuator 83 or 84 is provided.

  The actuator drive circuit 91 drives the first or second actuator 83 or 84 corresponding to the type of the disk in accordance with the detection signal from the disk type discriminating unit 22, and the first position at the position corresponding to the type of the disk. Alternatively, the second collimator lenses 74 and 75 are moved.

  The actuator drive circuit 91 uses the first or second aberration correction signal generated by the aberration correction circuit 90 that detects the defocus component of the light beam detected by the control detector 88, that is, the deviation of the divergence angle. The collimator lenses 74 and 75 are moved to an optimum position, that is, a position where the divergence angle of the light beam becomes a predetermined angle, and the deviation of the divergence angle and the deviation of the focal position associated therewith become zero. Move to position.

  The optical pickup 70 detects the occurrence of spherical aberration due to an error in the thickness of the protective substrate of the optical disk from the detection signals detected by the first or second photodetectors 81 and 82, and generates an aberration correction signal. The first or second actuator 83, 84 is driven by the aberration correcting circuit 90 and the actuator driving circuit 91 to move the first or second collimator lens 74, 75 to a position where the spherical aberration becomes zero. .

  Next, the optical path of the laser light emitted from the first and second light source units 71 and 72 in the optical pickup 70 will be described.

  A light beam having the first wavelength is emitted from the first light source unit 71 by the disc type discriminating unit 22 that detects that the optical disc 2 is the first optical disc 11.

  The light beam emitted from the first light source unit 71 is converted into a divergence angle by the first collimator lens 74 and emitted to the objective lens 73 side. A part of the light beam whose divergence angle is converted by the first collimator lens 74 is separated by the first beam splitter 76 and reflected to the control detector 88 side. The light beam separated by the first beam splitter 76 is aperture-limited by the second aperture filter 86, and is collected on the control detector 88 by the optical element 87.

  The control detector 88 detects the laser beam separated from the light beam incident on the objective lens 73, and detects the defocus component of the laser beam, that is, the deviation of the divergence angle of the light beam from a predetermined angle. . The actuator drive circuit 91 receives the aberration correction signal generated by the aberration correction circuit 90 based on the detection signal detected by the control detector 88 and drives the first actuator 83. The first actuator 83 moves the first collimator lens 74 so that the defocus component becomes an appropriate value, that is, the light beam is appropriately condensed on the signal recording surface 11a of the first optical disc 11. .

  The remaining part of the light beam having a predetermined appropriate divergence angle due to the movement of the first collimator lens 74 is transmitted through the first beam splitter 76 and is limited in aperture by the first aperture filter 85. The light is condensed on the signal recording surface 11 a of the first optical disk 11 by the lens 73.

  The light beam condensed on the signal recording surface 11a of the optical disc 11 is reflected by the signal recording surface 11a, passes through the objective lens 73 and the first beam splitter 76, and is converged by the first collimator lens 74. The optical path is branched from the incident light by the second beam splitter 77 and detected by the first photodetector 81.

  The actuator drive circuit 91 receives the aberration correction signal generated by the aberration correction circuit 90 based on the detection signal detected by the first photodetector 81 and drives the first actuator 83. The first actuator 83 moves the first collimator lens 74 so that the spherical aberration due to the error of the protective substrate thickness of the optical disc 2 becomes zero.

  The disc type discriminating unit 22 that detects that the optical disc 2 is the second or third optical disc 12 or 13 emits a light beam having the second or third wavelength from the second light source unit 72.

  The light beam emitted from the second light source unit 72 is converted into a divergence angle by the second collimator lens 75 and emitted to the first beam splitter 76 side.

  The second collimator lens 75 is moved to a predetermined position corresponding to the second or third optical disk 12, 13 by driving the second actuator 84 based on the signal detected by the disk type determination unit 22. .

  The light beam whose divergence angle is converted by the second collimator lens 75 is partly separated by the first beam splitter 76 and transmitted to the control detector 88 side. The light beam separated by the first beam splitter 76 is aperture-limited by the second aperture filter 86, and is collected on the control detector 88 by the optical element 87.

  The control detector 88 detects the laser beam separated from the light beam incident on the objective lens 73, and detects the defocus component of the laser beam, that is, the deviation of the divergence angle of the light beam from a predetermined angle. . The actuator drive circuit 91 receives the aberration correction signal generated by the aberration correction circuit 90 based on the detection signal detected by the control detector 88 and drives the second actuator 84. The second actuator 84 moves the second collimator lens 75 so that the defocus component becomes an appropriate value, that is, the light beam is appropriately focused on the signal recording surface 2a of the optical disc 2.

  The remaining part of the light beam having a predetermined appropriate divergence angle due to the movement of the second collimator lens 75 is reflected by the first beam splitter 76, is aperture-limited by the first aperture filter 85, and is objective. The light is condensed on the signal recording surfaces 12 a and 13 a of the second or third optical disk 12 or 13 by the lens 73.

  The light beam condensed on the signal recording surfaces 12a and 13a of the second or third optical disc is reflected by the signal recording surfaces 12a and 13a, reflected by the objective lens 73 and the first beam splitter 76, and second. Are converged by the collimator lens 75, and the optical path is branched from the incident light by the third beam splitter 78 and detected by the second photodetector 82.

  The actuator drive circuit 91 receives the aberration correction signal generated by the aberration correction circuit 90 based on the detection signal detected by the second photodetector 82 and drives the second actuator 84. The second actuator 84 moves the second collimator lens 75 so that the spherical aberration due to the error in the protective substrate thickness of the optical disc 2 becomes zero.

  The optical pickup 70 to which the present invention is applied separates the light beam before being focused on the optical disk by the first beam splitter, and detects the defocus component, that is, the divergence state of this light beam by the control detector. Because the detection signal moves the collimator lens so that the light beam is properly focused on the signal recording surface, for example, when the divergence angle of the light beam that has passed through the collimator lens changes due to vibration, impact, temperature change, etc. In addition, the control detector detects the divergence state of the light beam that has passed through the collimator lens, and the light beam is appropriately applied to the signal recording surface of the optical disc by adjusting the divergence angle of the light beam by moving the collimator lens. It can be condensed. Furthermore, by detecting the return light from the optical disk with a photodetector and moving the collimator lens, spherical aberration due to an error in the protective substrate thickness of the optical disk can be corrected well, and a stable focusing signal can be obtained. it can.

  That is, the optical pickup 70 to which the present invention is applied can be applied to a plurality of types of optical disks including optical disks capable of high-density recording using a light beam having a protective substrate thickness of 0.1 mm and a wavelength of about 405 nm as recording / reproducing light. On the other hand, it is possible to prevent a problem or the like from occurring in correction of spherical aberration due to a decrease in spot quality on each signal recording surface. As described above, the optical pickup 70 to which the present invention is applied improves the spot quality of the optical disk by the control detector and corrects the spherical aberration due to the error of the protective substrate thickness by the photodetector, so that a stable focusing signal is generated. As a result, a good recording / reproducing operation is possible.

  Further, the optical pickup 70 to which the present invention is applied condenses the light beam appropriately on the signal recording surface for three types of optical discs of different formats, and also has good spherical aberration due to disc protective substrate thickness error. Therefore, the three-wavelength compatible optical pickup is realized, and the optical components such as the objective lens and the control detector are shared, so that the miniaturization can be realized.

  The present invention can be applied to other disc formats than those described above. For example, optical discs include various types of recording / reproducing discs using optical modulation recording, optical discs including so-called magneto-optical recording, phase change recording, dye recording, and the like, specifically “CD-R / RW”, “DVD-”. "RAM", "DVD-R / RW", "DVD + RW", etc., or various magneto-optical recording media may be used. An optical disc is an optical disc in which a recording layer is divided into at least two or more recording regions having different optimum recording and / or reproducing light power on the recording layer, and an optical disc in which a plurality of recording layers are laminated via a transparent substrate. Also good.

It is a block diagram which shows the structure of the recording / reproducing apparatus to which this invention is applied. It is a block diagram explaining the example of the optical system of the optical pick-up to which this invention is applied. It is a block diagram explaining the other example of the optical system of the optical pick-up to which this invention is applied. It is a block diagram explaining the example of the optical system of the optical pick-up using a refractive power variable element. It is a block diagram explaining the further another example of the optical pick-up to which this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Recording / reproducing apparatus, 2 Optical disk, 3 Optical pick-up, 4 Spindle motor, 5 Feed motor, 9 Servo control circuit, 31 Light source part, 32 Objective lens, 33 Collimator lens, 34 1st beam splitter, 35 2nd beam splitter 36 optical detectors, 37 control detectors, 38 optical elements, 40 actuators, 41 first aperture filters, 42 second aperture filters, 44 aberration correction circuits, 45 actuator drive circuits,

Claims (6)

A light source that emits a light beam of a predetermined wavelength;
An objective lens for focusing the light beam emitted from the light source on the signal recording surface of the optical disc;
An optical element that is provided between the light source and the objective lens and converts a divergence angle of a light beam emitted from the light source;
Moving means for correcting spherical aberration by moving the optical element in the optical axis direction;
A light separating means provided between the optical element and the objective lens, for partially separating the light beam emitted from the optical element from the light beam incident on the objective lens;
A control detector for detecting the light beam separated by the light separating means,
An optical pickup for controlling the moving amount of the optical element by controlling the moving means based on the amount of light received by the control detector.   2. The optical pickup according to claim 1, wherein the optical element for converting the divergence angle is a collimator lens.   2. The optical pickup according to claim 1, wherein the optical element for converting the divergence angle is a beam expander. A light source that emits a light beam of a predetermined wavelength;
An objective lens for focusing the light beam emitted from the light source on the signal recording surface of the optical disc;
A refractive power variable element that is provided between the light source and the objective lens and corrects spherical aberration by varying the refractive power;
A light separating means that is provided between the refractive power variable element and the objective lens and separates a part of the light beam emitted from the refractive power variable element from the light incident on the objective lens;
A control detector for detecting the light beam separated by the light separating means,
An optical pickup that controls the refractive power of the refractive power variable element based on the amount of light received by the control detector. In a recording and / or reproducing apparatus comprising an optical pickup for recording and / or reproducing information with respect to an optical disk, and a disk rotation driving means for rotating the optical disk,
The optical pickup includes a light source that emits a light beam having a predetermined wavelength,
An objective lens for condensing the light beam emitted from the light source on the signal recording surface of the optical disc;
An optical element that is provided between the light source and the objective lens and converts a divergence angle of a light beam emitted from the light source;
Moving means for correcting spherical aberration by moving the optical element in the optical axis direction;
A light separating means provided between the optical element and the objective lens, for partially separating the light beam emitted from the optical element from the light beam incident on the objective lens;
A control detector for detecting the light beam separated by the light separating means,
A recording and / or reproducing apparatus, wherein the moving means is controlled by controlling the moving means based on the amount of light received by the control detector. In a recording and / or reproducing apparatus comprising an optical pickup for recording and / or reproducing information with respect to an optical disk, and a disk rotation driving means for rotating the optical disk,
The optical pickup includes a light source that emits a light beam having a predetermined wavelength,
An objective lens for focusing the light beam emitted from the light source on the signal recording surface of the optical disc;
A refractive power variable element that is provided between the light source and the objective lens and corrects spherical aberration by varying the refractive power;
A light separating means that is provided between the refractive power variable element and the objective lens and separates a part of the light beam emitted from the refractive power variable element from the light incident on the objective lens;
A control detector for detecting the light beam separated by the light separating means,
A recording and / or reproducing apparatus, wherein the refractive power of the refractive power variable element is controlled based on the amount of light received by the control detector.

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