JP2004055046A - Optical recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording and reproducing device which can raise the utilization efficiency of light of an optical system and also which has a constant control characteristic. <P>SOLUTION: The optical recording and reproducing device is provided with a light source which emits light, a condensing means for converging light to be incident on an effective aperture among the light emitted from the light source, a light shielding means for shading the other light heading toward the outside of the effective aperture of the condensing means among the light emitted from the light source, a first diffraction means for diffracting the light transmitted through the aperture of the condensing means among reflected rays of light reflected from the recording medium and a first photodetecting means which detects rays of light diffracted by the first diffraction means and outputs an electric signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical recording / reproducing device used for an optical disk drive.
[0002]
[Prior art]
2. Description of the Related Art In an optical recording / reproducing apparatus for recording / reproducing an optical recording medium such as an optical disk such as a CD (compact disk) and a DVD (digital versatile disk), a semiconductor laser element as a light source is provided by an objective lens which is a condensing means. The light emitted from the optical disc is converged on an optical recording medium to record and reproduce recorded information.
[0003]
In recent years, optical recording / reproducing apparatuses have been required to reduce power consumption from the viewpoint of long-term recording / reproducing. For this reason, it is required to improve the light use efficiency in an optical system mounted on an optical recording / reproducing apparatus.
[0004]
JP-A-8-249688 and JP-A-9-180246 disclose an objective lens of ± 1st-order diffracted light reflected by an information recording sequence on an optical recording medium in order to improve light use efficiency in an optical system. An optical recording / reproducing apparatus using light incident outside the effective aperture of the optical disc is disclosed. This conventional optical recording / reproducing apparatus is designed so that, of the ± 1st-order diffracted reflected light reflected by the optical recording medium, light incident outside the effective aperture of the objective lens is guided to the photodetector by the light guiding means. It is configured. With this configuration, it is possible to effectively use the light beam incident outside the effective aperture of the objective lens, and thus it is possible to improve the light use efficiency in the optical system.
[0005]
[Problems to be solved by the invention]
However, in the above-mentioned conventional optical recording / reproducing apparatus, of the light emitted from the semiconductor laser element as the light source, the light that travels outside the effective aperture of the objective lens also travels on the optical recording medium. After traveling outside the effective aperture of the objective lens from the semiconductor laser element, the light reflected on the optical recording medium passes through the inside or outside of the effective aperture of the objective lens, and then becomes a stray light component to the photodetector. Incident.
[0006]
Since the position of the objective lens relative to the optical recording medium is constantly changing, such a stray light component fluctuates. Therefore, a dynamic stray light component is generated in addition to a static stray light component. Such a static stray light component and a dynamic stray light component cause a problem that the control characteristics of the optical recording / reproducing apparatus become unstable.
[0007]
Further, in the conventional optical recording / reproducing apparatus, it is difficult to stably detect an error in focus control and tracking control because removal of an offset component caused by a shift of an objective lens is not considered. There's a problem.
[0008]
Furthermore, if the photodetector is arranged on the objective lens, wiring for supplying a drive voltage and wiring for detecting various signals are required, which complicates the configuration and reduces the size of the photodetector. Due to the increase in size, there is a problem that frequency response in focus control and tracking control is deteriorated.
[0009]
The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical recording / reproducing apparatus that can improve the light use efficiency of an optical system and has stable control characteristics. .
[0010]
[Means for Solving the Problems]
An optical recording / reproducing apparatus according to the present invention includes: a light source that emits light; a light-collecting unit that collects light that enters the effective aperture among light emitted from the light source onto a recording medium; and Light-shielding means for shielding light emitted to the outside of the effective aperture of the light-collecting means of the emitted light; and light transmitted through the effective aperture of the light-collecting means among reflected light reflected by the recording medium. Diffraction means for diffracting light, first light detection means for receiving an electric signal by receiving the light diffracted by the diffraction means, and out of the effective aperture of the condensing means of the reflected light. It is characterized by comprising a light guiding means for guiding light, and a second light detecting means for receiving the light guided by the light guiding means and detecting an electric signal.
[0011]
Another optical recording / reproducing apparatus according to the present invention includes a light source that emits light, and a light-condensing unit that condenses light incident on an effective aperture among the light emitted from the light source onto a recording medium; A reflection unit that reflects light of the light emitted from the light source toward the outside of the effective aperture of the light collection unit in a direction that does not reach the recording medium; and a reflection unit that reflects the light reflected by the recording medium. And a diffracting means for diffracting the light transmitted through the effective aperture of the focusing means, and a first light detecting means for receiving the light diffracted by the diffracting means and detecting an electric signal. I do.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the optical recording / reproducing apparatus according to the present invention, of the light emitted from the light source, the light going outside the effective aperture of the light condensing means is not blocked by the light blocking means and does not reach the recording medium. The electric signal can be detected by receiving the light that goes to the outside of the effective aperture out of the light. For this reason, it is possible to prevent light that goes outside the effective aperture of the light condensing means from being reflected by the recording medium and to be incident on the light detecting means as stray light. Efficiency of the light emitted from the light source can be improved.
[0013]
A hologram for diffracting light of the reflected light directed outward from the effective aperture of the light condensing means; and a light diffracted by the hologram, for reflecting the reflected light toward the second light detecting means. It is preferable to have reflection means. This is because, out of the reflected light, the light that goes outside the effective aperture is efficiently guided to the second light detecting means by the hologram.
[0014]
Preferably, the hologram is a blazed hologram. The blazed hologram can increase the diffraction efficiency and can prevent the generation of the diffracted light on the minus side with respect to the plus side, so that the light use efficiency can be further improved.
[0015]
Preferably, the reflection means is a reflection surface provided outside the hologram. This is because the use efficiency of light emitted from the light source can be improved with a simple configuration.
[0016]
It is preferable that the hologram is formed integrally with the light collecting means. This is because if they are formed integrally, they can be easily manufactured.
[0017]
The blazed hologram is divided along a direction parallel to an information recording sequence, which is a sequence of information recorded on the recording medium, and divided along a direction perpendicular to the information recording sequence. It is preferable to have a plurality of hologram regions. This is to support a tracking error detection method such as a phase difference method and a push-pull method.
[0018]
The second light detecting means has a plurality of light detectors provided at positions respectively corresponding to the plurality of hologram regions, and each light detector is orthogonal to the information recording sequence. It is preferable that each region is divided into a plurality of regions by the dividing line. This is for stably detecting the focus error and the tracking error.
[0019]
It is preferable that the light shielding means is constituted by a vapor-deposited film. This is because the light shielding means can be manufactured at low cost.
[0020]
It is preferable that the light shielding unit is formed integrally with the light collecting unit. This is because the light shielding means and the light collecting means are manufactured at low cost.
[0021]
It is preferable that the first light detection means is arranged so as to sandwich the light source. This is for receiving the light diffracted by the diffracting means. In a normal rectangular grating, diffracted light is generated in two directions, a plus direction and a minus direction. Therefore, if light detecting means is arranged on both sides of the light source (optical axis), the difference between the plus direction and the minus direction is obtained. Since both can be used, the light use efficiency can be further improved.
[0022]
It is preferable that the light source further includes a light-shielding band provided to shield light near the center where the light intensity is high and the optical resolution is low among the light emitted from the light source, and It is preferable to further include a phase modulation band provided for modulating the phase of light near the center where the light intensity is high and the optical resolution is low. This is because it can be applied to an optical recording / reproducing apparatus using a super-resolution method.
[0023]
It is preferable that the light condensing unit and the light guiding unit are integrally formed of resin. This is because the light collecting means and the light guiding means can be manufactured at low cost.
[0024]
It is preferable that the light collecting means, the light shielding means, and the light guiding means are formed integrally. This is because the light collecting means, the light shielding means, and the light guiding means are manufactured at low cost.
[0025]
The light collecting means, the light blocking means, and the light guiding means are integrally formed, and a substrate forming the light source, the first light detecting means, and the second light detecting means; It is preferable to further include a housing for holding the substrate. This is for manufacturing the optical recording / reproducing apparatus at low cost.
[0026]
Preferably, the diffraction means is provided on a surface of the light condensing means on the light source side, and the diffraction means and the light condensing means are preferably formed integrally. This is because the diffraction means and the light condensing means are manufactured at low cost.
[0027]
In another optical recording / reproducing apparatus according to the present invention, of the light emitted from the light source, light that goes outside the effective aperture of the light condensing means is reflected in a direction that does not reach the recording medium. For this reason, it is possible to prevent light that goes outward from the effective aperture of the light collecting means from being reflected by the recording medium and entering the light detecting means as stray light. As a result, an optical recording / reproducing apparatus having stable control characteristics can be obtained.
[0028]
It is preferable that the apparatus further includes a light amount monitoring light detector for monitoring the light amount of the light emitted from the light source, and the reflection unit reflects the light to the light amount monitoring light detector. This is for improving the use efficiency of the light emitted from the light source.
[0029]
A light guide for guiding the reflected light out of the effective aperture of the condensing means, and a second light for receiving the light guided by the light guide and detecting an electrical signal A light source, the first light detecting means, and the second light detecting means; and a substrate forming the light source, the first light detecting means, and the second light detecting means. The light amount monitor light detector is formed on the substrate. preferable. The front light APC with good controllability can be used without adding an external light amount monitoring element, and it can be applied to a recording apparatus.
[0030]
A light guide for guiding the reflected light out of the effective aperture of the condensing means, and a second light for receiving the light guided by the light guide and detecting an electrical signal It is preferable that the apparatus further comprises a detection unit, and a relative positional relationship among the light collection unit, the light guide unit, the light source, the first light detection unit, and the second light detection unit be fixed. .
[0031]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
FIG. 1 is a cross-sectional view schematically showing an optical recording / reproducing apparatus 100 according to an embodiment. The optical recording / reproducing apparatus 100 includes a housing 18 that opens toward the optical recording medium 25. A substantially flat semiconductor substrate 17 is provided on a bottom surface formed in the opening of the housing 18. At the approximate center of the surface of the semiconductor substrate 17, a concave portion having a slope is formed. The semiconductor laser element 6 is mounted in the recess formed in the semiconductor substrate 17 so as to face the slope formed in the recess. Around the semiconductor laser element 6 on the surface of the semiconductor substrate 17, the light detection unit 11 is formed on the surface of the semiconductor substrate 17 by semiconductor technology. The configuration of the light detection unit 11 is a commonly used configuration, and a detailed description thereof will be omitted. The light detection unit 5 is formed on the surface of the semiconductor substrate 17 outside the light detection unit 11 on the surface of the semiconductor substrate 17.
[0033]
FIG. 2A is a plan view schematically illustrating four light detectors 12 included in the light detection unit 5. In FIG. 2A, the light detection unit 11 is omitted for simplicity of description and illustration. The light detection unit 5 is provided with four light sources along a direction parallel to the information recording sequence, which is a sequence of information recorded on the optical recording medium 25, and along a direction perpendicular to the information recording sequence. It is divided into detectors 12. Each photodetector 12 is divided into two light receiving regions 14 by a dividing line 15 orthogonal to the information recording sequence.
[0034]
The housing 18 is provided with a hologram optical element 9 so as to cover an opening formed in the housing 18. The hologram optical element 9 has a hologram area 10 arranged so as to cover the semiconductor laser element 6 and the light detection unit 11. The configuration of the hologram region 10 is a commonly used configuration, and a detailed description thereof will be omitted.
[0035]
The objective lens 7 is provided between the hologram optical element 9 and the optical recording medium 25. The objective lens 7 is fixed to an objective lens driving device (not shown). The objective lens 7 has an effective aperture 8 representing a region where light can enter the objective lens 7. The value of the effective aperture 8 of the objective lens 7 is determined based on the resolution required for recording and reproducing the information recording sequence on the optical recording medium 25 and the tolerance of the optical recording medium 25 for tilt and the like. The effective aperture 8 of the objective lens 7 is about 0.45 for a CD and about 0.6 for a DVD. If the effective aperture 8 of the objective lens 7 is larger than this value, it is difficult to reproduce an information recording row on the optical recording medium 25 due to coma generated when tilt occurs in the optical recording medium 25. Thus, the upper limit of the effective aperture 8 of the objective lens 7 is limited.
[0036]
The diffraction unit 2 is provided around the objective lens 7. The diffraction unit 2 has a blazed hologram 3 arranged so as to surround the objective lens 7. In the diffraction unit 2, a reflection film 4 disposed outside the blazed hologram 3 is provided so as to extend outward with respect to the light detection unit 5. The reflection film 4 can be formed at low cost if formed by vapor deposition.
[0037]
FIG. 3 is a plan view schematically showing a blazed hologram region 13 in the blazed hologram 3. The blazed hologram 3 is divided into two pieces in a direction parallel to an information recording row which is a row of information recorded on the optical recording medium 25 so as to correspond to the four photodetectors 12. And has four blazed hologram regions 13 divided into two along the direction perpendicular to the information recording sequence. The reason why the blazed hologram 3 is divided along the direction parallel to and perpendicular to the information recording row on the optical recording medium 25 is a general phase difference method and a push-pull method as error detection methods in focus control and tracking control. Is to be able to use. Further, by dividing along the shift direction at the time when the objective lens 7 shifts, that is, the direction orthogonal to the information recording row, the error is stably detected together with the division of the light detection unit 5.
[0038]
The light-shielding film 1 is provided between the blazed hologram 3 and the semiconductor substrate 17 so as to surround the objective lens 7 when viewed from the semiconductor laser element 6 side. If the light-shielding film 1 is formed by vapor deposition, it can be produced at low cost. The blazed hologram 3, the reflection film 4, and the light-shielding film 1 are formed integrally with the objective lens 7 by resin.
[0039]
In the optical recording / reproducing apparatus 100 configured as described above, the semiconductor laser element 6 mounted in the concave portion formed in the semiconductor substrate 17 in the housing 18 emits a laser beam toward the slope formed in the concave portion. Then, the emitted laser beam is reflected by the inclined surface, and the reflected laser beam travels toward the hologram optical element 9 with a diverging angle, passes through the hologram area 10 provided in the hologram optical element 9, and passes through the objective lens 7. Are incident both inside the effective opening 8 and outside the effective opening 8. The laser beam that has entered the effective aperture 8 of the objective lens 7 passes through the objective lens 7 and is focused on the optical recording medium 25. The laser beam incident outside the effective aperture 8 of the objective lens 7 is shielded by the light shielding film 1. Therefore, the laser beam incident outside the effective aperture 8 of the objective lens 7 does not reach the optical recording medium 25.
[0040]
FIG. 4 is a schematic diagram for explaining the zero-order diffracted light 22 and the ± first-order diffracted light 23 reflected by the optical recording medium 25. The laser beam condensed on the optical recording medium 25 by the objective lens 7 is reflected by the optical recording medium 25, and becomes a 0th-order diffracted light 22 and ± 1st-order diffracted light 23. The zero-order diffracted light 22 reflected by the optical recording medium 25 enters the objective lens 7 again. The 0th-order diffracted light 22 that has passed through the objective lens 7 is diffracted in the hologram area 10 provided in the hologram optical element 9 and guided to the light detection unit 11. The light detection unit 11 detects an error detection signal and an information recording signal based on the incident zero-order diffracted light 22.
[0041]
Of the ± 1st-order diffracted light 23 reflected by the optical recording medium 25, the component incident into the effective aperture of the objective lens 7 is diffracted in the hologram area 10 like the 0th-order diffracted light 22 and guided to the light detection unit 11. . The light detection unit 11 detects an error detection signal and an information recording signal based on the components of the incident ± first-order diffracted light 23.
[0042]
The other components of the ± first-order diffracted light 23 reflected by the optical recording medium 25 and incident outside the effective aperture of the objective lens 7 are subjected to the objective by the blazed hologram region 13 divided into four parts constituting the blazed hologram 3. The light is diffracted in a direction away from the lens 7. Other components of the ± first-order diffracted light 23 diffracted by the four blazed hologram regions 13 are reflected by the reflection film 4 and guided to the four photodetectors 12 constituting the photodetection unit 5. When the other components of the ± first-order diffracted light 23 are diffracted by the blazed hologram 3, the other components of the ± first-order diffracted light 23 can be efficiently guided to the light detection unit 5.
[0043]
The other components of the ± 1st-order diffracted light 23 guided to the four photodetectors 12 become a focused spot image 16A. The other components of the ± 1st-order diffracted light 23 diffracted by the upper right blazed hologram region 13 shown in FIG. 3 become a condensed spot image 16A in the upper right photodetector 12 shown in FIG. The other components of the ± 1st-order diffracted light 23 diffracted by the lower right blazed hologram region 13 become the converging spot image 16A in the lower right photodetector 12 shown in FIG. 4A and shown in FIG. The other components of the ± 1st-order diffracted light 23 diffracted by the upper left blazed hologram region 13 become a condensed spot image 16A in the upper left photodetector 12 shown in FIG. The other components of the ± 1st-order diffracted light 23 diffracted by the dehologram region 13 become a converged spot image 16A in the lower left photodetector 12 shown in FIG.
[0044]
FIG. 2B is a plan view schematically showing another focused spot image 16B formed on each photodetector 12, and FIG. It is a top view which shows other condensing spot images 16C typically. As shown in FIGS. 2A to 2C, the condensed spot image on each photodetector 12 changes according to the distance between the optical recording medium 25 and the objective lens 7. When the laser beam emitted from the objective lens 7 is focused at a position farther than the surface of the optical recording medium 25 from the objective lens 7 as a result of driving the objective lens 7 toward the optical recording medium 25, FIG. As shown in a), each condensed spot image 16A appears outside each division line 15. When the laser beam emitted from the objective lens 7 is condensed on the surface of the optical recording medium 25, each condensed spot image 16B appears on each division line 15, as shown in FIG. When the laser beam emitted from the objective lens 7 is focused at a position closer to the surface of the optical recording medium 25 from the objective lens 7 as a result of driving the objective lens 7 away from the optical recording medium 25, FIG. As shown in c), each condensed spot image 16A appears inside each division line 15.
[0045]
Therefore, when a differential output from the two light receiving areas 14 in each photodetector 12 is detected, a focus error can be detected. The direction of the dividing line 15 that divides each photodetector 12 into two light receiving areas 14 is orthogonal to the information recording row recorded on the optical recording medium 25. For this reason, even if the relative positional relationship between the objective lens 7, the semiconductor laser element 6, and the photodetector 12 changes as a result of the objective lens 7 following the information recording sequence, the condensed spots 16 </ b> A to 16 </ b> C Since it moves along a direction parallel to the division line 15 on the photodetector 12, it does not affect the detection of the focus error.
[0046]
As described above, according to the present embodiment, of the light emitted from the semiconductor laser element 6, the light going outside the effective aperture 8 of the objective lens 7 is shielded by the light shielding film 1, so that the recording medium 25 Do not reach. For this reason, it is possible to prevent the light going outside the effective aperture 8 of the objective lens 7 from being reflected by the optical recording medium 25 and entering the light detection unit 11 as stray light. As a result, an optical recording / reproducing apparatus having stable control characteristics can be obtained.
[0047]
Further, according to the present embodiment, the diffraction unit 2 that diffracts components of the ± 1st-order diffracted light 23 reflected by the optical recording medium 25 toward the outside of the effective aperture 8 of the objective lens 7, and diffracts the light by the diffraction unit 2 And a photodetector 12 that receives the component of the ± 1st-order diffracted light 23 and detects an electric signal. Therefore, the reflected ± 1st-order diffracted light 23 can receive a component that goes outside the effective aperture 8 of the objective lens 7 and can detect an electric signal. As a result, the use efficiency of light emitted from the semiconductor laser device 6 can be improved.
Although an example in which the focus error is detected based on the output from each photodetector 12 has been described, the present invention is not limited to this. When the outputs from the respective photodetectors 12 are represented as S03b1, S03b2, S03b3, and S03b4, if the tracking error signal TE1 is obtained by the following equation 1, the tracking error can be detected according to the phase difference method.
[0048]
TE1 = (S03b1 + S03b4)-(S03b2 + S03b3) Equation 1
Further, if the tracking error signal TE2 is obtained by the following equation 2, the tracking error can be detected according to the push-pull method.
[0049]
TE2 = (S03b1 + S03b2)-(S03b3 + S03b4) Equation 2
Furthermore, a combination of various configurations can be selected in addition to the configuration in which the 0th-order diffracted light 22 reflected from the optical recording medium 25 is diffracted by the hologram region 10 on the hologram optical element 9 and guided to the light detection unit 11. Needless to say.
[0050]
Although the example in which the diffraction unit 2 is constituted by the blazed hologram 3 and the reflection film 4 is shown, the diffraction unit 2 is constituted by combining a plurality of reflection films, and the diffraction unit 2 is incident outside the effective aperture of the objective lens 7. The other components of the ± first-order diffracted light 23 may be guided to each photodetector 12.
[0051]
In the present embodiment, an example of a configuration in which the light shielding film 1 is deposited is shown, but a configuration using a reflection surface instead of the light shielding film 1 may be used. The configuration may be such that a laser beam incident outside the effective aperture 8 of the objective lens 7 is reflected by the reflecting surface in an arbitrary direction that does not affect the laser beam as a stray light component. For example, a photodetector for monitoring the light quantity is provided at an appropriate position, and the laser beam incident outside the effective aperture 8 is reflected and condensed by the reflection surface to the photodetector for monitoring the light quantity. It is also possible to monitor the amount of the emitted laser beam.
[0052]
In the present embodiment, an example is shown in which the semiconductor laser element 6 is mounted on the semiconductor substrate 17 on which the light detection units 5 and 11 are formed. The unit 11 may be individually mounted in the housing, or may be separately provided from the housing without having to be mounted in the same housing. In any case, the effects of the present invention can be obtained.
[0053]
In the present embodiment, an example is shown in which the ± 1st-order diffracted light 23 incident outside the effective aperture 8 of the objective lens 7 is used for focus error detection and tracking error detection. By detecting the tilt component and performing the tilt control together with the focus control and the tracking control, it is possible to configure an optical recording / reproducing apparatus with higher stability. It may be used to detect other types of physical quantities. What is necessary is just to arrange each light receiver appropriately according to the kind of optical recording medium.
[0054]
FIG. 5 is a cross-sectional view schematically showing another optical recording / reproducing apparatus 100A according to the embodiment, and FIG. 6A is a light beam recorded / reproduced by the other optical recording / reproducing apparatus 100A according to the embodiment. FIG. 6B is a schematic diagram for explaining the zero-order diffracted light reflected by the recording medium 25, and FIG. 6B is a schematic diagram for explaining another diffracted light reflected by the optical recording medium 25. (C) is a schematic diagram for explaining still another diffracted light reflected by the optical recording medium 25.
[0055]
The same components as those of the optical recording / reproducing apparatus 100 described above with reference to FIGS. 1 to 4 are denoted by the same reference numerals. Therefore, a detailed description of these components will be omitted. The difference from the optical recording / reproducing apparatus 100 described above is that a light-shielding band 19 is further provided in order to use the super-resolution method.
[0056]
A light-shielding band 19 is provided substantially at the center of the surface of the objective lens 7 on the semiconductor laser element 6 side. The light-shielding band 19, among the laser beams having a light intensity distribution emitted from the semiconductor laser element 6 and having passed through the hologram region 10, emits a component near the center where the light intensity is high and the optical resolution is low, to the light-shielding film 19. The light is shielded as shown in FIGS. 6A to 6C according to the positional relationship with the recording medium 25. According to the super-resolution method in which the light-shielding band 19 is provided, it is possible to make the focused spot on the optical recording medium smaller than the size determined by the numerical aperture of the effective aperture of the objective lens and the wavelength of the laser beam. For example, the resolution of the optical system can be further increased.
[0057]
The 0th-order diffracted light 22 of the laser beam reflected by the optical recording medium 25 enters the objective lens 7 again. The component of the zero-order diffracted light 22 that has passed through the objective lens 7 and entered the light-shielding band 19 is shielded by the light-shielding band 19, and does not reach the light detection unit 11 through the hologram area 10. For this reason, it is difficult to detect a focus error based on the zero-order diffracted light 22.
[0058]
However, in the optical recording / reproducing apparatus 100A according to the second embodiment, the ± first-order diffracted light 23 reflected by the optical recording medium 25 is incident outside the effective aperture of the objective lens 7, and the blazed hologram area The focus error can be detected by the 13 and the reflection film 4 based on other components of the ± 1st-order diffracted light 23 guided to the photodetector 12 constituting the photodetection unit 5. Therefore, the focus error can be stably detected without being affected by the light-shielding band 19.
[0059]
Although the example in which the light-shielding band 19 is provided to use the super-resolution method has been described, the present invention is not limited to this. A phase modulation band for modulating the phase of light near the center where the light intensity is high and the optical resolution is low among the lights emitted from the light source may be provided.
[0060]
FIG. 7 is a sectional view schematically showing still another optical recording / reproducing device 100B according to the embodiment. The same components as those of the optical recording / reproducing apparatus 100 described above with reference to FIGS. 1 to 4 are denoted by the same reference numerals. Therefore, a detailed description of these components will be omitted. The difference from the above-mentioned optical recording / reproducing apparatus 100 is that a hologram area 10A is provided instead of the hologram optical element 9 and the hologram area 10, and a housing 18A is provided instead of the housing 18. .
[0061]
A hologram area 10A is arranged on the surface of the objective lens 7 on the semiconductor laser element 6 side. The hologram area 10A is formed integrally with the objective lens 7. The objective lens 7 is formed integrally with the light shielding film 1 and the diffraction unit 2 and is assembled integrally with the housing 18A. Thus, the semiconductor laser element 6 and the light detection units 11 and 5 provided on the semiconductor substrate 17 disposed inside the housing 18A, and the objective lens 7 are integrally formed.
[0062]
Also in this configuration, the component incident outside the effective aperture of the objective lens 7 does not reach the optical recording medium 25, so that the reflected light does not enter the light detection unit 11 as a stray light component. Also, of the ± 1st-order diffracted light 23 reflected by the optical recording medium 25, the component incident outside the effective aperture of the objective lens 7 is used as an error detection signal by the diffraction unit 2, so that the light use efficiency is improved. The effect that enables realizing stable control characteristics is the same. As shown in FIG. 7, an integrated type in which the semiconductor laser element 6 and the light detection units 11 and 5 provided on the semiconductor substrate 17 disposed inside the housing 18A and the objective lens 7 are integrally formed. By doing so, the number of parts can be reduced. Further, since there is no need to consider a relative positional displacement when the objective lens 7 follows the information recording sequence, it is possible to obtain effects such as improvement of signal characteristics and enlargement of a design margin.
[0063]
The example in which the light shielding film 1 is formed integrally with the objective lens 7 has been described. However, if the relative positional relationship between the light shielding film 1 and the objective lens 7 is fixed, the light shielding film 1 It may be formed separately from the lens 7. For example, in a so-called integrated optical recording / reproducing apparatus in which a semiconductor laser element is mounted in a movable portion integrally with an objective lens, since the relative positional relationship between the light-shielding film and the objective lens can be fixed, The film may be formed separately from the objective lens. The configuration of the light-shielding film 1 may be any configuration that can prevent the laser beam incident outside the effective aperture of the objective lens 7 from reaching the optical recording medium 25, and is limited to the configuration of the present embodiment. It is not done.
[0064]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an optical recording / reproducing apparatus capable of improving the light use efficiency of an optical system and having stable control characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an optical recording / reproducing apparatus according to an embodiment.
FIG. 2 is a plan view schematically showing four photodetectors constituting a photodetection unit provided in the optical recording / reproducing apparatus according to the embodiment;
(A) is a top view which shows typically the condensed spot image formed on each photodetector,
(B) is a plan view schematically showing another condensed spot image formed on each photodetector,
(C) is a plan view schematically showing still another condensed spot image formed on each photodetector.
FIG. 3 is a plan view schematically showing a blazed hologram area in a blazed hologram provided in the optical recording / reproducing apparatus according to the embodiment.
FIG. 4 is a schematic diagram for explaining 0th-order diffracted light and ± 1st-order diffracted light reflected by an optical recording medium for recording and reproducing by the optical recording and reproducing apparatus according to the embodiment.
FIG. 5 is a cross-sectional view schematically showing another optical recording / reproducing apparatus according to the embodiment.
FIG. 6A is a schematic diagram for explaining diffracted light reflected by an optical recording medium on which recording and reproduction is performed by another optical recording and reproduction device according to the embodiment;
(B) is a schematic diagram for explaining another diffracted light reflected by the optical recording medium,
(C) is a schematic diagram for explaining still another diffracted light reflected by the optical recording medium.
FIG. 7 is a sectional view schematically showing still another optical recording / reproducing apparatus according to the embodiment.
[Explanation of symbols]
1 Shading film
2 Diffraction unit
3 Blazed hologram
4 Reflective film
5 Light detection unit
6 Semiconductor laser device
7 Objective lens
8 Effective aperture
9 Hologram optical element
10 Hologram area
11 Light detection unit
12 Photodetector
13 Blazed hologram area
14 Light receiving area
15 Dividing line
17 Substrate
18 Housing
19 shading belt
22 0th order diffracted light
23 ± 1st order diffracted light
25 Optical recording media

Claims (20)

A light source for emitting light,
Condensing means for condensing light incident on the effective aperture out of the light emitted from the light source on a recording medium,
Light-shielding means for shielding the light emitted from the light source out of the effective aperture of the light-collecting means toward the outside;
Diffraction means for diffracting light transmitted through the effective aperture of the light condensing means out of the reflected light reflected by the recording medium,
First light detection means for receiving the light diffracted by the diffraction means and detecting an electric signal,
A light guide unit that guides light that is directed to the outside of the effective aperture of the light collection unit in the reflected light,
An optical recording / reproducing apparatus, comprising: a second light detecting means for receiving the light guided by the light guiding means and detecting an electric signal. The light guide means, a hologram for diffracting the reflected light out of the effective aperture of the light condensing means toward the outside,
The optical recording / reproducing apparatus according to claim 1, further comprising: a reflection unit configured to reflect light diffracted by the hologram toward the second light detection unit. The optical recording and reproducing apparatus according to claim 2, wherein the hologram is a blazed hologram. 3. The optical recording / reproducing apparatus according to claim 2, wherein the reflection unit is a reflection surface provided outside the hologram. The optical recording / reproducing apparatus according to claim 2, wherein the hologram is formed integrally with the condensing means. The blazed hologram is divided along a direction parallel to an information recording sequence, which is a sequence of information recorded on the recording medium, and divided along a direction perpendicular to the information recording sequence. 4. The optical recording and reproducing apparatus according to claim 3, wherein the optical recording and reproducing apparatus has a plurality of hologram regions. The second light detection means has a plurality of light detectors provided at positions respectively corresponding to the plurality of hologram regions,
The optical recording / reproducing apparatus according to claim 6, wherein each of the photodetectors is divided into a plurality of regions by dividing lines orthogonal to the information recording sequence. 2. The optical recording / reproducing apparatus according to claim 1, wherein said light shielding means is constituted by a vapor-deposited film. 2. The optical recording / reproducing apparatus according to claim 1, wherein the light shielding unit is formed integrally with the light collecting unit. 2. The optical recording / reproducing apparatus according to claim 1, wherein the first light detection unit is disposed so as to sandwich the light source. 2. The optical recording / reproducing apparatus according to claim 1, further comprising a light-shielding band provided to shield light near a center having a high light intensity and a low optical resolution among the light emitted from the light source. 2. The optical recording / reproducing apparatus according to claim 1, further comprising a phase modulation band provided for modulating the phase of light near the center having high light intensity and low optical resolution among the lights emitted from the light source. . The optical recording / reproducing apparatus according to claim 1, wherein the light condensing unit and the light guiding unit are integrally formed of a resin. The optical recording / reproducing apparatus according to claim 1, wherein the light condensing unit, the light blocking unit, and the light guide unit are integrally formed. The light collecting means, the light shielding means, and the light guide means are formed integrally,
A substrate forming the light source, the first light detecting means, and the second light detecting means;
The optical recording / reproducing apparatus according to claim 1, further comprising a housing that holds the light guide unit and the substrate. The diffraction means is provided on the light source side surface of the light condensing means,
The optical recording / reproducing apparatus according to claim 1, wherein the diffraction means and the light condensing means are formed integrally. A light source for emitting light,
Condensing means for condensing light incident on the effective aperture out of the light emitted from the light source on a recording medium,
Reflecting means for reflecting the light emitted from the light source toward the outside of the effective aperture of the light collecting means in a direction not reaching the recording medium,
Diffraction means for diffracting light transmitted through the effective aperture of the light condensing means out of the reflected light reflected by the recording medium,
An optical recording / reproducing apparatus, comprising: first light detecting means for receiving the light diffracted by the diffraction means and detecting an electric signal. The apparatus further includes a light amount monitor light detector for monitoring the light amount of light emitted from the light source,
18. The optical recording / reproducing apparatus according to claim 17, wherein the reflection unit reflects the light to the light amount monitoring photodetector. A light guide unit that guides light that is directed to the outside of the effective aperture of the light collection unit in the reflected light,
Second light detecting means for receiving the light guided by the light guiding means and detecting an electric signal,
Further comprising a substrate forming the light source, the first light detecting means, and the second light detecting means,
19. The optical recording / reproducing apparatus according to claim 18, wherein the light quantity monitor photodetector is formed on the substrate. A light guide unit that guides light that is directed to the outside of the effective aperture of the light collection unit in the reflected light,
A second light detecting unit that receives the light guided by the light guiding unit and detects an electric signal,
The optical recording / reproducing apparatus according to claim 17, wherein a relative positional relationship among the light condensing unit, the light guide unit, the light source, the first light detection unit, and the second light detection unit is fixed.

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