JP2008065919A - Optical pickup and optical disk drive using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can quickly plot images on the label surface, and to provide an optical disk drive incorporating it. <P>SOLUTION: This optical pickup 100 is composed of a laser light source 1 emitting a light beam, a recording and reproducing objective lens 11 to condense the light beam emitted from the laser light source 1 on the recording surface of an optical disk, and an objective lens 12 exclusive to plotting images on the label surface of the disk. When plotting the images on the label surface of the disk, it plots the images on the label surface by condensing the light beam through the objective lens 12 exclusive to image plotting. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that performs drawing on a label surface of an optical disc, and an optical pickup mounted thereon.

  In recent years, optical disc drives capable of recording and reproducing information such as CD-R / RW and DVD-R / RW have become widespread, and a surface called a label surface on the side opposite to the recording surface of the optical disc In addition, a technique for drawing with a light beam irradiated by an optical pickup mounted on an optical disk apparatus (optical disk drive) (hereinafter referred to as a label surface drawing technique) has been proposed. (For example, patent document 1). In recent years, optical disc drives compatible with such a label surface drawing technique are becoming popular.

JP 2004-213802 A

  Label surface drawing technology uses the thermal reaction of the light beam emitted from the optical pickup to perform drawing, so it is necessary to accurately control the amount of light beam applied to the optical disc label surface and to perform drawing. We need to secure the amount of light.

  For this reason, the optical pickup has means for detecting the light amount of the light beam emitted from the laser light source in order to control the light amount of the light beam emitted from the laser light source, and the detected light amount is fed back to the laser light source. As a result, the light quantity of the light beam applied to the optical disk is accurately controlled.

  Moreover, in order to secure the light quantity necessary for drawing, the light utilization rate of the optical system in the optical pickup is improved and the output of the laser light emitting element is increased.

  In an optical disk drive compatible with label surface drawing technology that has been announced in recent years, laser light of a 785 nm band of an optical pickup is emitted and focused on the optical disk label surface to perform drawing on the label surface.

  However, the objective lens for condensing the laser beam of the current optical pickup on the disk surface is designed to transmit the transparent substrate of the disk and form an optimum spot on the disk recording surface. A large spherical aberration occurs on the disc label surface side, and the spot on the disc surface is blurred, resulting in a decrease in the intensity of the spot on the disc surface. FIG. 10 shows the intensity distribution corresponding to the LD vertical direction of the spot on the disc. The solid line shows the spot intensity distribution on the disk with no aberration, and the oblique line shows the spot intensity distribution when focused on the label surface. The intensity distribution in the LD vertical direction of the spot on the disk has basically the same intensity distribution as in FIG.

As shown in FIG. 10, with respect to the spot intensity distribution on the disc when there is no aberration, the spot condensed on the label surface has an intensity of about 1/6 compared with the intensity center, and the light utilization efficiency. In the focus and tracking control method, there is no structure such as pits and guide grooves on the disk surface, so there is a tracking error. The signal cannot be detected.

  Similarly, in the focus control, the spot on the detector is greatly blurred due to the influence of the spherical aberration, so it is difficult to perform feedback control using a detection method such as an astigmatism method. Generally, focus and tracking control is performed by open control.

  Therefore, the disc has a tilt (hereinafter referred to as surface runout). A focus error or tracking error occurs due to impact or vibration from the disc or the outside, and an optimal spot can always be formed on the disc label surface. There is a problem that it becomes difficult and the quality of drawing deteriorates.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical pickup capable of drawing on a label surface at high speed and an optical disk drive including the same.

  In order to achieve the above object, according to the first aspect of the present invention, a laser light source for emitting a light beam, and a recording / reproducing objective for condensing the light beam emitted from the laser light source on a recording surface of an optical disc. There is provided an optical pickup including a lens and a drawing-dedicated objective lens for a label surface of an optical disk.

  In order to achieve the above object, according to the second aspect of the present invention, the optical pickup for recording / reproduction used for recording or reproduction of the optical disc, and the drawing only provided with the function of drawing on the label surface of the optical disc An optical disc apparatus equipped with an optical pickup is provided.

  In order to achieve the above object, according to the third aspect of the present invention, a laser light source, an objective lens for condensing a light beam emitted from the laser light source on an optical disk, and light emission of the objective lens An optical pickup including a plate-like optical component disposed on the side is provided.

  In order to achieve the above object, according to the fourth aspect of the present invention, an optical pickup, a plate-like optical component movably arranged on the light emitting side of the optical pickup, and the optical component are moved. There is provided an optical disc device including a moving mechanism for causing the optical disc to move.

In order to achieve the above object, according to the fifth aspect of the present invention, a first optical disk that is recorded or reproduced by a first light beam, and a second light beam having a wavelength different from that of the first light beam. An optical pickup that supports recording or reproduction of two types of optical disks, ie, a second optical disk that is recorded or reproduced by the first optical source, a first laser light source that emits a first light beam, and a second that emits a second light beam. A laser light source, and a compatible objective lens having a diffractive lens structure capable of recording or reproducing with respect to the first optical disc and the second optical disc,
The compatible objective lens has an outer peripheral region through which the second light beam passes during recording or reproduction of the second optical disc and does not pass through the first optical beam during recording or reproduction of the first optical disc. Provided is an optical pickup characterized in that, when a surface is drawn, the first light beam transmitted through the outer peripheral region is designed to form a spot on the label surface that enables drawing on the label surface. .

  According to the optical pickup of the present invention and the optical disc including the same, it is possible to perform drawing on the label surface of the optical disc at high speed.

  Hereinafter, an optical pickup according to the present invention and an optical disc apparatus including the optical pickup will be described by way of examples. However, the present invention is not limited to the following examples.

  In the first embodiment, an optical pickup corresponding to an optical disc drive capable of recording and reproducing DVDs and CDs and drawing on a label surface opposite to the disc recording surface at high speed will be described.

  FIG. 1 is a diagram showing an optical system configuration of the optical pickup 100. First, a description will be given of the optical path during DVD recording and reproduction. A light beam is emitted from the laser light source 1 as divergent light. The laser light source 1 is a semiconductor laser that emits light at a wavelength in the 660 nm band. The semiconductor laser is generally used as a laser light source for recording or reproducing on a DVD disk, and such a semiconductor laser is also assumed in the laser light source 1 of this configuration.

  In the figure, the optical path formed by the check hatching indicates the light beam 2, and the optical path formed by the alternate long and short dash line indicates the light beam 3.

  The light beam 2 emitted from the DVD laser light source 1 passes through the diffraction grating 4, is reflected by the prism 5, passes through the beam splitter 6, and enters the front monitor 8.

  In the optical disk drive, when recording a signal on the optical disk, it is necessary to accurately control the light quantity of the laser light source in order to irradiate the optical disk with a predetermined light quantity, and the front monitor 8 detects a change in the light quantity of the laser light source 1, It is installed to control the amount of light emitted from the laser light source 1. The output signal of the front monitor 7 is fed back to a drive circuit (not shown) of the laser light source 1 to control the amount of light emitted from the laser light source 1 and irradiate the optical disk with a desired amount of light.

  The light beam 3 emitted from the DVD laser light source 1 passes through the diffraction grating 4, is reflected by the prism 5 and the beam splitter 6, and enters the lens 7. The light beam 3 is converted into a substantially parallel light beam by the lens 7. The light beam 3 emitted from the lens 7 is reflected on the rising mirror 9 in the z direction in the drawing and is condensed on an optical disk (not shown) by the compatible objective lens 11 mounted on the actuator 10.

  The light beam 3 is reflected by the optical disc, passes through the compatible objective lens 11, and reaches the photodetector 14 through the rising mirror 9, the lens 7, the beam splitter 6, and the detection lens 13.

  Next, the optical path to the front monitor that monitors the light emission power of the laser will be described.

  The light beam 3 is given a predetermined astigmatism when passing through the beam splitter 6, and is used for detecting a focus error signal (hereinafter referred to as FES) of the optical disk by the astigmatism method. Since the astigmatism method is a very general FES detection method, its description is omitted. The detection lens 13 has a function of rotating the astigmatism direction in a predetermined direction and simultaneously determining the size of the light spot on the photodetector 14. The light beam 3 guided to the optical detector 14 detects an information signal recorded on the optical disk, and controls the position of a light spot collected on the optical disk such as a tracking error signal (hereinafter referred to as TES) and FES. Used for signal detection.

  Next, the optical path during CD recording and reproduction will be described. A light beam is emitted from the laser light source 15 as divergent light. The laser light source 15 is a semiconductor laser that emits light at a wavelength of 785 nm band. The semiconductor laser is generally used as a laser light source for recording or reproducing on a CD disk, and the laser light source 15 of the present configuration assumes such a semiconductor laser.

  In the figure, the optical path formed by the check hatching indicates the light beam 16, and the optical path formed by the alternate long and short dash line indicates the light beam 17.

  The light beam 16 emitted from the CD laser light source 15 passes through the diffraction grating 18, the prism 5, and the beam splitter 6 and enters the front monitor 8. As in the case of DVD, the front monitor 8 is installed to detect a change in the light amount of the laser light source 1 and control the emitted light amount of the laser light source 1. The output signal of the front monitor 8 is fed back to a drive circuit (not shown) of the laser light source 1 to control the amount of light emitted from the laser light source 1 and irradiate the optical disk with a desired amount of light.

  The light beam 17 emitted from the CD laser light source 15 passes through the diffraction grating 18 and the prism 5, is reflected by the beam splitter 6, and enters the lens 7. The light beam 17 is converted into a substantially parallel light beam by the lens 7. The light beam 17 emitted from the lens 7 is reflected on the rising mirror 9 in the z direction in the figure, and is condensed on an optical disk (not shown) by the compatible objective lens 11 mounted on the actuator 10.

  The light beam 17 is reflected by the optical disk, passes through the compatible objective lens 11, and reaches the photodetector 14 through the rising mirror 9, the lens 7, the beam splitter 6, and the detection lens 13. The light beam 17 that has reached the photodetector 14 is given predetermined astigmatism when transmitted through the beam splitter 6 as in the case of DVD, and is used for detecting the FES of the optical disk by the astigmatism method. The detection lens 13 has a function of rotating the astigmatism direction in a predetermined direction and simultaneously determining the size of the light spot on the photodetector 14. The light beam 3 guided to the photodetector 14 is used for detection of an information signal recorded on the optical disk and detection of a position control signal of a light spot collected on the optical disk such as TES and FES.

  Here, the operation of the optical pickup at the time of drawing on the disc label surface will be described.

  For drawing on the disc label surface, the light beam of the CD laser light source 15 is used. In addition to the compatible objective lens 11, the actuator 10 is equipped with a drawing-purpose objective lens 12 for drawing on the disc label surface. The optical pickup of the present embodiment switches from the compatible objective lens 11 to the drawing-purpose objective lens 12 when drawing on the label surface, and condenses the light beam emitted from the CD laser light source 15 onto the label surface by the drawing-purpose objective lens 12. And draw. Thus, by using the drawing objective lens 12, high-speed drawing on the disc label surface can be performed. The drawing-dedicated objective lens 12 is a single-wavelength objective lens that collects only a single-wavelength light beam from the CD laser light source 15.

  The objective lens is usually designed in consideration of the thickness of the cover glass between the objective lens and the sample. The drawing-purpose objective lens 12 is designed such that the design value of the cover glass thickness is 0 mm, and the light beam emitted from the CD laser light source is optimally condensed on the disc label surface. . That is, it is designed so that the laser beam for CD collected by the drawing objective lens 12 becomes substantially non-aberrated and is optimally condensed on the label surface. By using this drawing-dedicated objective lens 12, an optimum spot can be formed on the disc label surface, and the light utilization efficiency can be improved.

  Further, by designing so that the optimum spot is formed on the disc label surface, the spot can be condensed on the detector 14 to detect the FES, and feedback control using the spot can be performed.

  Also in tracking, the movement of the spot on the detector is monitored in a DC manner so that the amount of positional deviation in the tracking direction of the objective lens due to external vibration or impact can be accurately grasped, and feedback control is performed. Is possible. As a result, there is an effect that high-quality drawing can be performed even in a state where there is a surface shake disk or external impact or vibration.

  In the above-described configuration, the cover glass thickness design value of the drawing-purpose objective lens 12 is preferably 0 mm, but is not limited thereto, and the cover glass thickness t is 0.6 mm or less, which is closer to the disc label surface than a normal CD objective lens. There is no problem if the cover glass thickness is designed so that the aberration of the focused spot is sufficiently small and the spot intensity is improved. For example, when a light beam of a predetermined wavelength (for example, a light beam for CD recording / reproducing) collected by the drawing-purpose objective lens 12 passes through a cover glass having a thickness of 0.6 mm or less, it becomes substantially no aberration, and the focal plane In other words, it may be designed in advance so as to be optimally focused on the label surface. In addition, when the light beam of a predetermined wavelength collected by the drawing objective lens 12 passes through a cover glass having a thickness greater than 0 mm and less than or equal to 0.1 mm, the light beam is substantially free of aberration, and is optimally focused on the focal plane. A drawing-dedicated objective lens may be designed as described above.

  In this embodiment, the objective lens is designed with a light beam wavelength dedicated for CD recording / reproduction, but the present invention is not limited thereto. For example, a light beam in a wavelength region other than the light beam wavelength for CD recording / reproduction is used. , Lenses dedicated to other wavelengths (such as DVD objective lenses and BDs) that are designed to be nearly non-aberrated when transmitted through a cover glass with a thickness of 0.6 mm or less, and to be optimally focused on the focal label surface. There may be no problem even if the optical beam for CD recording / reproducing is condensed on the label surface by such an objective lens for other wavelengths.

  In the second embodiment, an optical disk apparatus including an optical pickup dedicated for high-speed drawing having only a function of drawing on an optical disk label surface will be described.

  FIG. 2 is a diagram showing a configuration of an optical disk apparatus including a high-speed drawing dedicated optical pickup having only a function of drawing on the optical disk label surface.

  The optical disk apparatus 200 includes a spindle motor 20 that rotates a disk, a DVD / CD compatible optical pickup 102 that records or reproduces the optical disk, an electronic circuit board 21 that controls the DVD / CD compatible pickup 102, and an optical disk label surface. A drawing-dedicated optical pickup 101 for performing drawing and an electronic circuit board 22 for controlling the drawing-dedicated optical pickup 101 are provided.

  At the time of recording or reproducing the optical disc 19, a focus error signal and a tracking error signal are generated by the DVD / CD compatible optical pickup 102, and feedback control of focus and tracking is performed by the electronic circuit board 21, so that optimum recording or reproduction is performed. Can be done.

  Further, the DVD / CD compatible optical pickup 102 can perform recording or reproduction at an arbitrary place by moving in the disk radial direction (y direction in the figure) by the power of a stepping motor (not shown).

  Next, the operation at the time of drawing on the optical disk label surface will be described. A drawing-dedicated optical pickup 101 is used for drawing on the optical disk label surface. The configuration of the drawing-dedicated optical pickup 101 will be described in detail later.

  The drawing-dedicated optical pickup 101 is arranged on the opposite side (disc label surface side) with respect to the DVD / CD compatible optical pickup with the disc interposed therebetween.

  A focus error signal is generated by the drawing-dedicated optical pickup 101, and feedback control is performed by the electronic circuit board 22, so that focusing can be performed at an optimum position for drawing.

  Further, in tracking in the disk radial direction (y direction in the figure), drawing is performed on the optical disk label surface by controlling the opening of a stepping motor (not shown) and the pickup objective lens in the tracking direction.

  By adopting this configuration, there is an effect that it is possible to delete the operation of inserting the disk required for drawing on the disk label surface into the drive upside down. It is also possible to draw on the label surface while performing the recording / reproducing operation of the disc.

  Moreover, there is an effect that high-speed drawing can be performed by using an optical pickup dedicated for drawing on the label surface of the optical disk.

  In this embodiment, two control boards are mounted for DVD / CD compatible pickup control and drawing-only pickup control. However, the present invention is not limited to this, and the two boards may be integrated into one board. It does n’t matter.

  In addition, an optical pickup dedicated to drawing on the label surface is mounted, but this is not limited, and a DVD / CD compatible pickup or a CD pickup may be an optical pickup having a drawing function on the optical disk label surface. Absent.

  Next, the drawing-dedicated optical pickup 101 having only the function of drawing on the optical disc label surface will be described.

  FIG. 3 shows the configuration of the optical system of the drawing-dedicated optical pickup 101. A light beam is emitted as diverging light from the laser light source 15 as a drawing light beam. The laser light source 15 is a semiconductor laser that emits light at a wavelength of 785 nm band. The semiconductor laser is generally used as a laser light source for drawing on the disk label surface, and such a semiconductor laser is also assumed in this configuration. However, the present invention is not limited to this, and the semiconductor laser can be changed accordingly if the label surface can be drawn by laser light in other wavelength regions.

  In the figure, the optical path formed by the check hatching indicates the light beam 16, and the optical path formed by the alternate long and short dash line indicates the light beam 17.

  The light beam 16 emitted from the laser light source 15 passes through the beam splitter 6 and enters the front monitor 8. Even at the time of drawing on the label surface, the front monitor 8 detects a change in the light amount of the laser light source 15 as in the first embodiment. The output signal of the front monitor 8 is fed back to a drive circuit (not shown) of the laser light source 15 to control the amount of light emitted from the laser light source 15 and irradiate the optical disk with a desired amount of light.

  On the other hand, the light beam 17 emitted from the laser light source 15 is reflected by the beam splitter 6, reflects the rising mirror 9 in the z direction in the figure, and is mounted on the actuator 10 by the finite objective lens 23 (not shown). ) Condensed on top.

  The light beam 17 is reflected by the optical disk label surface, and reaches the photodetector 14 through the finite objective lens 23, the rising mirror 9, and the beam splitter 6. The light beam 17 is given a predetermined astigmatism when passing through the beam splitter 6 and is used for detecting the FES of the optical disk by the astigmatism method. The FES is detected by the light beam 17 guided to the photodetector 14, and is used for detecting the position control signal of the light spot collected on the optical disk.

  Thus, drawing on the label surface can be performed while controlling the position of the light beam on the label surface of the optical disk.

  The drawing-purpose objective lens 23 is a finite objective lens whose incident light beam is not parallel light. The finite objective lens 23 is designed to have a numerical aperture of 0.45 or less, and the image height characteristics can be suppressed even under a state where the lateral magnification of the objective lens is low.

  As a result, there is an effect that the performance of the spot on the disc label surface can be maintained substantially equal to that at the lens center even when the finite objective lens is mounted and the lens is shifted in the radial direction.

  Further, the tracking error signal cannot be detected on the disc label surface because the label surface has a different structure from the recording surface. Therefore, by using a dedicated optical pickup for drawing on the disc label surface, there is no need to perform feedback control for real-time tracking, and the diffraction grating 5 used in the first embodiment can be eliminated.

  Furthermore, there is an effect that the finite objective lens can be used even in a state where the light magnification is good and the optical magnification is low, and the lens 6 mounted in the first embodiment is deleted by using the finite objective lens. There is an effect that can be done.

  Also in this configuration, the same effect as described in the first embodiment can be obtained by using an objective lens optimal for the disc label surface. As a result, it is possible to provide a drawing-dedicated optical pickup that is a simple optical system and is inexpensive and capable of high-speed drawing.

  In this embodiment, the optical configuration of the optical pickup for drawing only is a configuration using a finite objective lens. However, the present invention is not limited thereto, and an infinite system objective lens may be used. In the case of using a lens, a lens for making divergent light substantially parallel light is required.

  In the description of the first to third embodiments, the astigmatism method is used for FES. However, the present invention is not limited to this. Conventional FES detection methods such as the so-called knife edge method, front-rear differential method, and spot size method are used. It doesn't matter.

  In addition, a method may be used in which the total light received by the light detector when the lens is driven is monitored and the lens is driven so that the total light received by the light detector is maximized. In that case, the photodetector need not be divided and may be divided into one if it can be adjusted.

  In the third embodiment, an optical pickup dedicated for high-speed drawing having only a function of drawing on the disc label surface will be described.

  FIG. 4 is a diagram showing an optical system configuration of the optical pickup 103.

  First, the optical system of the optical pickup 103 will be described. The light beam emitted from the laser light source 15 is emitted as divergent light. As with the optical pickup 101, the laser light source 15 is assumed to be a semiconductor laser that emits a light beam having a wavelength of about 785 nm. In the figure, the optical path formed by the check hatching indicates the light beam 16, and the optical path formed by the alternate long and short dash line indicates the light beam 17.

  The light beam 16 emitted from the laser light source 15 passes through the beam splitter 16 and enters the front monitor 8.

  On the other hand, the light beam 17 emitted from the laser light source 15 reflects the beam splitter 6, reflects the rising mirror 9 in the z direction in the drawing, and the optical disc label surface (not shown) by the finite objective lens 23 mounted on the actuator 10. Focused on top.

  The light beam 17 is reflected by the optical disk label surface, is reflected by the finite objective lens 23, the rising mirror 9, and the beam splitter 6, and returns to the laser light source (hereinafter, the reflected light returning to the laser light source is returned as light. ).

  Due to the influence of the return light, a self-coupling effect occurs in the laser light source, and the output of the laser light source changes. A method using this phenomenon is called a SCOOP method, which is a technique that has been studied as a detection method for FES.

  The outline of the SCOOP method will be described below.

  FIG. 5 is a diagram of IL characteristics of the laser injection current I and the laser output L with and without return light.

  The characteristic without return light is indicated by a solid line 25, and the characteristic with return light is indicated by a solid line 24. When the laser output L is compared with the solid lines 25 and 24 at a certain injection current threshold 26, a difference occurs in the laser output. At this time, if the light is condensed at an optimum spot on the disk, the return light to the laser light source 15 becomes maximum, and the characteristic of the solid line 24 with the return light is obtained. Further, when the spot on the disk is blurred, the return light to the laser light source is also blurred, so the return light is reduced and the characteristic of the solid line 25 without return light is obtained.

  Focus control can be performed by detecting this difference in characteristics.

  However, in the laser IL-characteristic, when the laser emission output becomes high, the solid line 24 with return light becomes a characteristic close to the solid line 25 without return light, and focus control becomes difficult. Therefore, in this embodiment, a method of driving a laser drive signal at the time of drawing on the optical disc label surface with a pulse signal is adopted.

  FIG. 6 shows a laser drive signal at the time of drawing on the optical disk label surface. In this way, by drawing on the label surface with the pulse signal having the laser light amount high output 27 and the laser light amount low output 28, drawing is performed at the high output 27, and the sampling detection of the focus error signal is performed at the low output 28. By doing so, there is an effect that the SCOOP method can be used.

  As a result, the detector 14 suitable for the optical systems of Embodiments 2 to 3 can be eliminated, and an inexpensive and small space dedicated optical pickup for drawing can be provided.

  In the fourth embodiment, a high-speed drawing dedicated optical pickup having only a drawing function on the disc label surface will be described.

  FIG. 7 shows a schematic view of the vicinity of the actuator 10 of the drawing-dedicated optical pickup according to the present embodiment.

  In the optical pickup of the fourth embodiment, the objective lens 23 dedicated to drawing on the disc label surface mounted on the actuator 10 shown in FIG. 3 is changed to an objective lens used for an optical pickup for DVD / CD recording or reproduction. 7 is the same as the optical pickup shown in the second embodiment except that a cover glass that assumes the thickness of the transparent substrate of the disk is provided between the disk 30 and the objective lens 11 as shown in FIG.

  A light beam 7 shown in FIG. 7 is a light beam emitted from a laser light source in the same manner as in the third embodiment, and is reflected by the beam splitter 6 shown in FIG. 3 or shown in FIG. 1 described in the first embodiment. It is assumed that the light beam transmitted through the lens 7 is converted to a substantially parallel light beam provided before or after reflection by the rising mirror 9.

  As shown in FIG. 7, the light beam 17 passes through the DVD / CD compatible objective lens 11 mounted on the actuator 10, passes through the cover glass 29 assuming the thickness of the transparent substrate of the disc, and the disc label surface. It is focused on.

  By adopting such a configuration, it is possible to correct the spherical aberration by the cover glass 29 even with a high-NA DVD / CD compatible lens for DVD or CD recording or reproduction conventionally used. The best spot is formed on the disc label surface, and there is an effect that high-speed drawing on the disc label surface can be performed.

  In addition, the present invention is a high-speed drawing dedicated light having only a function of drawing on a disc label surface by adding only a cover glass 29 to a currently used DVD / CD recording / reproducing optical pickup or CD recording / reproducing optical pickup. There is an effect that it can be changed to a pickup.

  This effect has the effect of reducing the cost of the optical pickup because the number of production of similar optical pickups increases, leading to lower prices of purchased parts.

  In addition, since the cover glass 29 is provided, the same effect as that of the drawing-purpose objective lens can be obtained. Therefore, the same effect as that described in the first embodiment can be obtained.

  In this embodiment, the cover glass 29 is mounted on the actuator 10 of the optical pickup. However, the present invention is not limited to this. The cover glass is mounted on the optical disk apparatus side, and the optical pickup is used for drawing on the disk label surface. It does not matter if the cover glass is arranged between the objective lens and the disk (light emitting side of the optical pickup).

  At that time, the cover glass mounted on the optical disc apparatus side can be slid by a moving mechanism having a slide mechanism or the like, and when drawing the disc label surface, the cover glass is arranged between the objective lens and the disc label surface, It is also possible to adopt a configuration in which the cover glass is retracted from between the objective lens and the disk during reproduction. As a result, even an optical disk apparatus equipped with an optical pickup for DVD / CD recording / reproduction can be recorded / reproduced of DVD / CD only by changing to the above configuration including the cover glass and the moving mechanism for moving the cover glass. It is possible to support high-speed drawing on the disc label surface.

  Here, a cover glass is used, but an optical component of any shape or material may be used as long as the spherical aberration can be corrected and the label surface can be irradiated with a substantially non-aberration light beam.

  In Example 5, DVD and CD can be recorded and reproduced, and an optical pickup compatible with an optical disk drive capable of drawing at high speed on a label surface opposite to the disk recording surface, and a DVD / CD compatible objective lens mounted thereon explain about.

  FIG. 8 shows a schematic configuration of the optical system of the optical pickup according to the present embodiment. The optical pickup of this embodiment shown in FIG. 8 is the same as the optical system of the optical pickup shown in FIG. 1 except that the DVD / CD compatible objective lens 32 that also supports label surface drawing and the actuator 10 on which it is mounted are different. It is. The actuator has basically the same configuration as a conventional actuator. Therefore, the description other than the drawing compatible DVD / CD compatible objective lens 32 is basically omitted, and only the features will be described.

  FIG. 9 schematically shows the state of the light beam collected by the DVD / CD compatible objective lens 32 that is compatible with drawing.

The DVD / CD compatible objective lens 32 has a diffractive lens structure capable of recording or reproducing with respect to two types of optical disks of CD and DVD. The diffractive lens structure of the DVD / CD compatible objective lens 32 has an order m1 (m1 is an integer) diffracted light by a light beam having a wavelength λ1 of CD and an order m2 (m2 is an integer different from m1) by a light beam having a wavelength λ2 of DVD. Diffracted light is a ratio of diffraction order times wavelength (λ1 × m1) / (λ2 × m2) = 0.75 to 0.99 (1)
It is designed so as to satisfy the above condition, and has wavelength dependence so as to form a good wavefront for each of the two types of optical disks.

  Further, as shown in FIG. 9, the DVD / CD compatible objective lens 32 includes a CD recording / reproducing numerical area 0.5 (hereinafter referred to as a CD area) 34 and the CD area 34. A DVD recording / reproducing area having a numerical aperture of 0.65 (hereinafter referred to as a DVD area) 35 is provided. The area 33 excluding the CD area 34 from the DVD area 35 is not used at the time of recording or reproducing a CD, and hereinafter this area 33 will be referred to as a DVD dedicated area. The DVD / CD compatible objective lens 32 is configured so that a light beam that passes through a DVD exclusive area 33 that is not used when recording or reproducing a CD forms an optimum spot on the label surface 31 of the CD disk 30 when drawing on the label surface. Optimized for. That is, the DVD / CD compatible objective lens 32 can condense the DVD light beam onto the DVD during DVD recording or reproduction, and the CD light beam onto the CD during CD recording or reproduction. There is an area formed so as not to be condensed, but at the time of drawing on the label surface of the optical disc, a CD light beam transmitted through this area forms a spot that enables drawing on the label surface. Designed to.

  The DVD exclusive area 33 of the DVD / CD compatible objective lens 32 is designed so that DVD recording or reproduction is possible with respect to laser light (for example, diffracted light of order m2) used for DVD recording or reproduction. For the CD laser light (for example, diffracted light of order m1) used for drawing the label surface, the cover glass is designed to be 0.6 mm or less, for example, so that drawing on the label surface is possible. Moreover, you may design in the range of cover glass thickness 0mm-0.1mm.

  By designing such an objective lens, at the time of drawing on the label surface 31, the light beam that passes through the DVD exclusive area 33 and is condensed on the disk label surface and the CD area 34 are transmitted. It is possible to perform drawing on the label surface by the light beam irradiated onto the disc label surface.

  As a result, it is possible to provide an optical pickup capable of recording or reproducing DVDs and CDs and capable of drawing on a disc label surface at high speed.

  Further, by adopting the configuration of this method, it is possible to cope with high-speed drawing only by changing the objective lens, and there is an effect that there is no influence of a design change on other parts mounted on the optical pickup.

  In the design of the objective lens, the intensity of the spot on the label surface is increased by defocusing the light transmitted through the CD region 34 in the range of about −20 to −40 μm. In this case, it is desirable to design the lens in consideration of such a defocus amount.

  In this embodiment, the numerical aperture of the CD is set to 0.5 and the numerical aperture of the DVD is set to 0.65. However, the present invention is not limited to this, and the numerical aperture of the DVD is sufficiently larger than the numerical aperture of the CD. I do not care.

  In the above embodiment, the optical disk apparatus provided with the optical pickup dedicated to drawing on the label surface and the optical pickup for recording / reproducing on the optical disk has been described. Can be configured as an optical disc label printer that performs only drawing on the label surface.

  The optical pickup according to the present invention and the optical disc apparatus including the optical pickup have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

1 is a diagram illustrating a configuration of an optical system of an optical pickup in Embodiment 1. FIG. FIG. 6 is a diagram illustrating a configuration of an optical disc device according to a second embodiment. 6 is a diagram illustrating a configuration of an optical system of an optical pickup in Embodiment 2. FIG. 6 is a diagram illustrating a configuration of an optical system of an optical pickup in Embodiment 3. FIG. It is a figure which shows the IL characteristic of the laser light source in Example 3. FIG. FIG. 10 is a diagram illustrating a drive current signal to a laser in Example 3. FIG. 10 is a diagram illustrating a configuration in the vicinity of an actuator of an optical pickup according to a fourth embodiment. FIG. 10 is a diagram illustrating a configuration of an optical system of an optical pickup according to a fifth embodiment. FIG. 10 is a diagram illustrating an optical path of an optical pickup objective lens in Example 5. It is a figure which shows the light spot intensity distribution corresponding to LD perpendicular | vertical direction on a disc label surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Optical pick-up, 101 ... Optical pick-up, 102 ... Optical pick-up, 103 ... Optical pick-up, 200 ... Optical disk apparatus, 1 ... DVD laser light source, 4 ... Diffraction grating, 5 ... Prism, 6 ... Beam splitter, 7 ... Lens, 8 ... Front monitor, 9 ... Rising mirror, 10 ... Actuator, 11 ... DVD / CD compatible Objective lens, 12 ... Objective lens for drawing, 13 ... Detection lens, 14 ... Photodetector, 15 ... CD laser light source, 18 ... Diffraction grating, 19 ... Disc, 20. .. Spindle motor, 21... Electronic circuit board, 22... Electronic circuit board, 23... Finite objective lens, 29 .. cover glass, 32 .. DVD / CD compatible objective lens, 30. Disk, 31 ... label surface

Claims (15)

An optical pickup for irradiating a recording surface of an optical disc with a light beam and detecting a reflected light beam reflected by the recording surface,
A laser light source for emitting the light beam;
A recording / reproducing objective lens for condensing the light beam emitted from the laser light source on the recording surface of the optical disc;
An optical pickup comprising: a drawing-dedicated objective lens for the label surface of the optical disc. The optical pickup according to claim 1,
The drawing objective lens is substantially free of aberration when a light beam of a predetermined wavelength collected by the drawing objective lens passes through a cover glass having a thickness of 0.6 mm or less, and is optimally focused on the focal plane. An optical pickup characterized by being designed in advance. The optical pickup according to claim 1,
The drawing objective lens has substantially no aberration when a light beam of a predetermined wavelength collected by the drawing objective lens passes through a cover glass having a thickness greater than 0 mm and not greater than 0.1 mm. An optical pickup that is preliminarily designed so as to be optimally focused. The optical pickup according to claim 1,
The drawing-dedicated objective lens is preliminarily designed so that the light beam having a predetermined wavelength collected by the drawing-dedicated objective lens becomes substantially non-aberration and is optimally condensed on the focal plane. pick up. In the optical pick-up as described in any one of Claim 1 to 4,
The drawing objective lens is designed to have a numerical aperture of 0.45 or less. The optical pickup according to any one of claims 2 to 5,
The optical pickup according to claim 1, wherein the light beam having a predetermined wavelength is a light beam for recording or reproducing a CD. The optical pickup according to any one of claims 1 to 6,
The recording / reproducing objective lens and the drawing-purpose objective lens are mounted on an actuator,
The actuator uses the recording / reproducing objective lens and the recording / reproducing objective lens so that the recording / reproducing objective lens is used during recording or reproduction of the optical disc, and the drawing-dedicated objective lens is used when drawing the label surface of the optical disc. An optical pickup characterized by switching between a drawing-dedicated objective lens. An optical disc apparatus having a function of drawing on a label surface of an optical disc,
An optical pickup for recording / reproduction used for recording or reproduction of the optical disc;
An optical disk apparatus comprising a drawing-dedicated optical pickup having only a function of drawing on the label surface. The optical disc apparatus according to claim 8, wherein
The drawing-dedicated optical pickup drives a laser light source with pulsed light emission, and irradiates the label surface of the optical disc with a pulsed light beam to perform drawing. When the laser driving current is low, the SCOOP method is used. An optical disc apparatus, wherein a focus error signal at the time of drawing is detected by detecting a sampling focus error. In an optical pickup with a function of drawing on the label surface of an optical disc,
A laser light source;
An objective lens for condensing the light beam emitted from the laser light source onto the optical disc;
An optical pickup comprising a plate-like optical component disposed on the light emitting side of the objective lens. The optical pickup according to claim 10, wherein
The optical pickup is characterized in that the optical component is a cover glass. In an optical disc apparatus having a function of drawing on the label surface of an optical disc,
An optical pickup for irradiating the optical disc with a light beam and detecting a reflected light beam from the optical disc;
A plate-like optical component movably disposed on the light exit side of the optical pickup;
An optical disc device comprising a moving mechanism for moving the optical component. An optical disc apparatus according to claim 12, wherein
The moving mechanism is configured such that the optical component is disposed on the light emitting side of the optical pickup so that the light beam transmitted through the optical component is irradiated onto the label surface of the optical disc only when drawing on the label surface of the optical disc. Optical disk drive that moves Supports recording or playback of two types of optical disks: a first optical disk that is recorded or reproduced by a first light beam and a second optical disk that is recorded or reproduced by a second light beam having a wavelength different from that of the first light beam. An optical pickup,
A first laser light source that emits the first light beam;
A second laser light source that emits the second light beam;
A compatible objective lens having a diffractive lens structure capable of recording or reproducing with respect to the first optical disc and the second optical disc,
The compatible objective lens can focus the second light beam on the second optical disk during recording or reproduction of the second optical disk, and the first light during recording or reproduction of the first optical disk. There is an outer peripheral region formed so that a beam is not condensed on the first optical disc, and the first light beam transmitted through the outer peripheral region is drawn to the label surface when drawing the label surface of the optical disc. An optical pickup characterized in that it is designed to form spots on the label surface that enable the drawing of the label. 15. The optical pickup according to claim 14, wherein
The optical pickup characterized in that the first optical disc is a CD and the second optical disc is a DVD.

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