JP4770915B2 - Optical pickup head device and optical information device - Google Patents

Description

  The present invention relates to an optical pickup head device and an optical information device for recording, reproducing or erasing information on an optical storage medium for recording information with marks and spaces.

  In recent years, a high-density and large-capacity optical disk called DVD has been put to practical use as a high-density and large-capacity storage medium, and is widely spread as an information medium that can handle a large amount of information such as moving images. FIG. 14 is a diagram showing a configuration of a general optical system used in an optical pickup in an optical disc system as an optical information device capable of recording / reproducing. In the conventional configuration, a tracking error signal is detected by irradiating an optical storage medium with three beams (see, for example, Patent Document 1).

  A light source 1 such as a semiconductor laser emits a linearly polarized divergent beam 70 having a wavelength λ of 405 nm. The divergent beam 70 emitted from the light source 1 is converted into parallel light by the collimator lens 53 having a focal length f1 of 15 mm, and then enters the diffraction grating 58. The beam 70 incident on the diffraction grating 58 is branched into three beams of 0th order and ± 1st order diffracted light. The 0th-order diffracted light is a main beam 70a for recording / reproducing information, and the ± 1st-order diffracted light is two sub-beams 70b and 70c for a differential push-pull (hereinafter referred to as DPP) method for detecting a TE signal. The ratio of the diffraction efficiency of the zero-order diffracted light 70a of the diffraction grating 58 and one first-order diffracted light 70b or 70c is usually set to 10: 1 to 20: 1 in order to avoid unnecessary recording by the sub-beams. Here it is 20: 1. The three beams 70a to 70c generated by the diffraction grating 58 are transmitted through the polarization beam splitter 52, transmitted through the quarter-wave plate 54 and converted into circularly polarized light, and then an objective lens having a focal length f2 of 2 mm. The light beam is converted into a convergent beam at 56, transmitted through the transparent substrate 41a of the optical storage medium 41, and condensed on the information recording surface 41c. The optical storage medium 41 has two information recording surfaces 41b and 41c. Here, a state in which the beam 70 condensed by the objective lens 56 is focused on the information recording surface 41c is shown. Yes. The optical storage medium 41 includes a transparent substrate 41a and information recording surfaces 41b and 41c. The distance d2 from the light incident surface of the optical storage medium 41 to the information recording surface 41c is 100 μm, and the distance d1 between the information recording surfaces 41b and 41c. Is 25 μm. Although not shown here, the period tp of the tracks formed on the information recording surfaces 41b and 41c is 0.32 μm. The aperture of the objective lens 56 is limited by the aperture 55, and the numerical aperture NA is 0.85. The transparent substrate 41a has a thickness of 0.1 mm and a refractive index n of 1.62. The equivalent reflectivities of the information recording surfaces 41b and 41c are about 4 to 8%, respectively. Here, the equivalent reflectivity is that when the light quantity of the beam incident on the optical storage medium 41 is 1, the beam when the light is emitted again from the optical storage medium 41 after being reflected by the information recording surface 41b or 41c. It shows the amount of light. The information recording surface 41c absorbs or reflects most of the light amount of the incident beam, but the information recording surface 41b transmits about 50% of the incident beam in order to reach the information recording surface 41c. And absorb or reflect the remaining 50% of the light amount.

  FIG. 15 shows the relationship between the beam on the information recording surface 41c and the track. On the information recording surfaces 41b and 41c of the optical storage medium 41, continuous grooves serving as tracks are formed, and Tn-1, Tn, and Tn + 1 are tracks, respectively. Information is recorded on the groove. The track pitch tp is 0.32 μm. When the main beam 70a is positioned on the track Tn, the beams are arranged so that the sub beam 70b is positioned between the tracks Tn-1 and Tn and the sub beam 70c is positioned between the tracks Tn and Tn + 1. That is, the distance L in the direction orthogonal to the main beam and sub beam tracks is 0.16 μm.

  The beam 70 reflected by the information recording surface 41 c passes through the objective lens 56 and the quarter-wave plate 54, is converted into linearly polarized light that is 90 degrees different from the forward path, and then reflected by the polarization beam splitter 52. The beam 70 reflected from the polarization beam splitter 52 passes through a condensing lens 59 having a focal length f3 of 30 mm, is converted into convergent light, and enters the photodetector 30 via the cylindrical lens 57. Astigmatism is imparted to the beam 70 when it passes through the cylindrical lens 57.

FIG. 16 schematically shows the relationship between the photodetector and the beam. The photodetector 30 has eight light receiving units 30a to 30h, the light receiving units 30a to 30d receive the beam 70a, the light receiving units 30e to 30f receive the beam 70b, and the light receiving units 30g to 30h receive the beam 70c, respectively. The light receiving units 30a to 30h output current signals I30a to I30h corresponding to the received light amounts. A focus error (hereinafter referred to as FE) signal is obtained by the astigmatism method using signals I30a to I30d output from the photodetector 30, that is, by calculation of (I30a + I30c) − (I30b + I30d). The TE signal is obtained by the differential push-pull method (hereinafter referred to as DPP method) , that is, by the calculation of {(I 30a + I30d) − (I30b + I30c)} − C · {(I30e + I30g) − (I30f + I30h)}. Here, C is a coefficient determined by the ratio of the diffraction efficiency of the zero-order diffracted light of the diffraction grating 58 and one first-order diffracted light. The FE signal and the TE signal are amplified and phase compensated to a desired level, and then supplied to actuators 91 and 92 for moving the objective lens 56 to perform focus and tracking control. The information (hereinafter referred to as RF) signal recorded on the information recording surface 41c is obtained by the calculation of I30a + I30b + I30c + I30d.

However, when an optical storage medium having a plurality of information recording surfaces is used, the beam is reflected on an information recording surface other than the desired information recording surface and then enters the photodetector. The beams 71a to 71c are beams incident on the photodetector 30 by being reflected by the information recording surface 41b, which is an information recording surface different from the desired information recording surface 41c on which information is to be recorded and reproduced. is there. At this time, the beam 71a and the beam 70b or the beam 71a and the beam 70c overlap with each other, thereby generating a light and dark distribution due to interference. The distribution of light and darkness due to this interference varies depending on the fluctuation of the surface of the optical storage medium and the uneven thickness of the transparent substrate 41a, and affects the TE signal. Beams 70b and 70c are sub-beams, while beam 71a is the main beam. Since the sub beams 70b and 70c have a smaller amount of light than the main beam 70a, the beam 71a and the beam 70b and the beam 71a and the beam 70c have the largest change in brightness due to interference.

FIG. 17 is a diagram showing a state when a TE signal by the DPP method obtained when the beams 70a to 70c are scanned in a direction orthogonal to the track is observed with an oscilloscope. When the TE signal is detected with the conventional configuration as described above, 70a to 70c reflected by the information recording surface 41c, which is the desired information recording surface, and the desired information recording surface 41c are different information recording surfaces. The beams 71a to 70c reflected by the information recording surface 41b overlap with each other, and the light and dark distribution due to interference is generated in the beams 70a to 70c, so that the amplitude and symmetry of the TE signal vary greatly. When tracking control is performed using this TE signal, the tracking control becomes unstable, and there is a problem that information cannot be recorded and reproduced with high reliability.

  SUMMARY OF THE INVENTION The present invention provides an optical pickup head device and an optical information device that can reduce the variation in TE signal amplitude and record or reproduce information with high reliability in consideration of such problems of conventional optical information devices. For the purpose.

  An optical pickup head device according to the present invention includes: a light source that emits a light beam; a diffractive unit that receives a beam emitted from the light source and generates a plurality of diffracted beams of 0th order and 1st order and above; Condensing means for receiving a plurality of beams from the optical storage medium, condensing on the optical storage medium, beam branching means for receiving the plurality of beams reflected by the optical storage medium and branching the beam, and branching by the beam branching means And a light detection means for outputting a signal corresponding to the received light quantity. The 0th-order diffracted light generated by the diffraction means is used as a main beam, and 1 is generated by the diffraction means. Two or more diffracted lights of the next order are used as a first sub-beam and a second sub-beam, and the light detection means has a plurality of light receiving portions, and the plurality of beams are approximately one virtual on the light detection means. Straight line When the direction of the imaginary straight line is the first direction and the direction orthogonal to the first direction is the second direction on the surface of the light detection means that receives the beam, The size of the beam in the first direction is smaller than the size in the second direction, thereby achieving the above object.

  Preferably, in the above optical pickup head device, the plurality of beams are substantially focused in the first direction on a surface of the light detection unit that receives the plurality of beams.

  The main beam, the first sub beam, and the second sub beam are received by a plurality of light receiving units, respectively. The plurality of light receiving units that receive the main beam are defined as a first light receiving unit group, and the first sub beam is used as the first sub beam. A plurality of light receiving units that receive light are defined as a second light receiving unit group, a plurality of light receiving units that receive the second sub-beam are defined as a third light receiving unit group, and the first light receiving unit group is larger in the first direction. The height may be smaller than the size in the second direction.

  The size of the second light receiving unit group in the first direction is smaller than the size of the second direction, and the size of the third light receiving unit group in the first direction is the size of the second direction. It may be characterized by being smaller than that.

  Moreover, it is good also as having a light-receiving part other than the said 1st-3rd light-receiving part group.

  Further, a light receiving portion may be provided between the first light receiving portion group and the second light receiving portion group, and between the first light receiving portion group and the third light receiving portion group.

  In addition, the second light receiving unit group or the third light receiving unit group may include three or more light receiving units.

  The second light receiving unit group or the third light receiving unit group may include six light receiving units.

  Another optical pickup head device according to the present invention includes: a light source that emits a light beam; a diffraction unit that receives a beam emitted from the light source and generates a plurality of diffracted beams of zero order and first order; and Condensing means for receiving a plurality of beams from the diffracting means and condensing them on the optical storage medium, and receiving the plurality of beams reflected by the optical storage medium and converting the beams into a first beam group and a second beam group A beam branching means for branching the light beam, and a light detection means for receiving the first beam group and the second beam group and outputting a signal corresponding to the received light quantity, and is generated by the diffraction means. The first-order diffracted light is a main beam, the first-order or higher-order diffracted light generated by the diffracting means is a first sub-beam and a second sub-beam, and the light detecting means has a plurality of light-receiving sections, The main beam constituting the beam group of The beam, the first sub-beam, and the second sub-beam are arranged approximately on one virtual straight line on the light detection means, and the direction of the virtual straight line is set on the surface of the light detection means that receives the beam. When the first direction is the second direction and the direction perpendicular to the first direction is the second direction, the size of the plurality of beams in the first direction is smaller than the size of the second direction, thereby The above objective is achieved.

  In the above optical information apparatus, the light amount of the second beam group is preferably larger than the light amount of the first beam group.

  An optical information device according to the present invention includes a light source that emits a light beam, a condensing unit that receives the beam emitted from the light source and focuses the light on the optical storage medium, and a beam reflected by the optical storage medium. An optical pickup head device comprising: a beam branching means for receiving and branching the beam; and a light detection means for receiving the beam branched by the beam branching means and outputting a signal corresponding to the received light quantity; and the light detection And a tracking error signal generating means for generating a tracking error signal which is a signal for performing control for irradiating a beam to a desired track in response to a signal output from the means, and the optical storage medium records information. A plurality of information recording surfaces, and when recording information on the information recording surface of the information recording medium, the beam has a first power level and a second power level, The power level of 1 is smaller than the second power level, and the tracking error signal generation means samples and holds the signal output from the light detection means at the timing of the first power level, and then the tracking error signal. This achieves the above objective.

  Another optical information device according to the present invention includes an optical pickup head device according to any one of the above, an optical storage medium, a drive unit that changes a relative position of the optical pickup head device, and the optical The above object is achieved by including an electrical signal processing unit that receives signals output from the pickup head device and performs calculations to obtain desired information.

  According to the configuration of the invention described above, the present invention is an optical information that can reduce or prevent variations in TE signal amplitude and can record or reproduce information with high reliability even when an optical storage medium having a plurality of information recording surfaces is used. A device can be realized.

  As described above, according to the present invention, even when an optical storage medium having a plurality of information recording surfaces is used, an optical information apparatus capable of reducing or changing TE signal amplitude and recording or reproducing information with high reliability is provided. realizable.

  Embodiments of an optical information device and an optical pickup head device according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numeral represents the same component or the same function and operation.

(Embodiment 1)
FIG. 1 shows the configuration of an optical information apparatus as an embodiment of the present invention. The optical pickup head device 4 (also referred to as an optical pickup) irradiates the optical storage medium 41 with a laser beam having a wavelength λ of 405 nm, and reproduces a signal recorded on the optical storage medium 41. The transfer controller 5 moves the optical pickup head device 4 in the radial direction of the optical storage medium 41 in order to record or reproduce information at an arbitrary position of the optical storage medium 41. The motor 6 that drives the optical storage medium 41 rotates the optical storage medium 41. The first control means 7 controls the optical pickup head device 4, the transfer controller 5, and the motor 6. The amplifier 8 amplifies the signal read by the optical pickup head device 4. Reference numeral 9 denotes a second control means. The output signal of the amplifier 8 is input to the second control means 9. The second control means 9 generates a servo signal such as an FE signal or a TE signal required when the optical pickup head device 4 reads the signal of the optical storage medium 41 from this signal, and this is used as the first control. Output to means 7. The signal input to the second control means 9 is an analog signal, but the second control means 9 digitizes (binarizes) the analog signal. The demodulating means 10 analyzes the signal read from the optical storage medium 41 and digitized, reconstructs the original data such as video and music, and the reconstructed signal is output from the output means 14. The detection unit 11 detects an address signal or the like from the signal output from the second control unit 9 and outputs it to the system control unit 12. The system control means 12 identifies the optical storage medium based on the physical format information read from the optical storage medium 41 and the optical storage medium manufacturing information (optical storage medium management information), decodes the recording / reproducing conditions, etc. Control the entire information device. When recording / reproducing information on / from the optical storage medium 41, the first controller 7 drives and controls the transfer controller 5 in accordance with instructions from the system controller 12. As a result, the transfer controller 5 moves the optical pickup head device 4 to a desired position on the information recording surface 41 c, and the optical pickup head device 4 records and reproduces information on the information recording surface 41 c of the optical storage medium 41.

  FIG. 2 is a diagram showing an example of the configuration of the optical pickup head device according to the present invention. The light source 1 emits a linearly polarized divergent beam 70 having a wavelength λ of about 405 nm. The divergent beam 70 emitted from the light source 1 is converted into parallel light by the collimator lens 53 having a focal length f1 of 15 mm, and then enters the diffraction grating 83. The beam 70 incident on the diffraction grating 83 is branched into three beams of 0th order and ± 1st order diffracted light. The 0th-order diffracted light becomes the main beam 70a for recording / reproducing information, and the ± 1st-order diffracted light becomes the two sub-beams 70b and 70c for the DPP method for detecting the TE signal. The ratio of the diffraction efficiency of the 0th-order diffracted light 70a and one 1st-order diffracted light 70b or 70c of the diffraction grating 83 is usually set to 10: 1 to 20: 1 in order to avoid unnecessary recording by the sub-beams. Here it is 20: 1. The three beams 70 a to 70 c generated by the diffraction grating 83 are transmitted through the polarization beam splitter 52, and then enter the pair of concave lens 81 and convex lens 82 to be transmitted. The beam 70 transmitted through the convex lens 82 is transmitted through the quarter-wave plate 54 and converted into circularly polarized light, and then converted into a convergent beam by the objective lens 56 having a focal length f2 of 2 mm. The light passes through the substrate 41a and is condensed on the information recording surface 41c. The optical storage medium 41 has two information recording surfaces 41b and 41c. Here, a state in which the beam 70 condensed by the objective lens 56 is focused on the information recording surface 41c is shown. Yes. The distance d2 from the light incident surface of the optical storage medium 41 to the information recording surface 41c is 100 μm, and the distance d1 between the information recording surfaces 41b and 41c is 25 μm. Although not shown here, the period tp of the tracks formed on the information recording surfaces 41b and 41c is 0.32 μm. The aperture of the objective lens 56 is limited by the aperture 55, and the numerical aperture NA is 0.85. The transparent substrate 41a has a thickness of 0.1 mm and a refractive index n of 1.62. The equivalent reflectivities of the information recording surfaces 41b and 41c are about 4 to 8%, respectively. Here, the equivalent reflectivity is that when the light quantity of the beam incident on the optical storage medium 41 is 1, the beam when the light is emitted again from the optical storage medium 41 after being reflected by the information recording surface 41b or 41c. It shows the amount of light. The information recording surface 41c absorbs or reflects most of the light amount of the incident beam, but the information recording surface 41b transmits about 50% of the incident beam in order to reach the information recording surface 41c. The remaining light amount of about 50% is absorbed or reflected.

  The position of the concave lens 81 is changed by an actuator 93 so that the amount of spherical aberration given to the beams 70a to 70c can be adjusted. The amount of spherical aberration of the beams 70a to 70c focused on the information recording surfaces 41b and 41c varies depending on the distance from the surface of the optical storage medium 41 to the information recording surfaces 41b and 41c. The spherical aberration is corrected using the concave lens 81 and the convex lens 82 so that the spherical aberration of the beam 70 condensed on 41c is reduced. By providing the concave lens 81 and the convex lens 82, information can be recorded on both the information recording surfaces 41b and 41c with little spherical aberration.

  The beams 70 a to 70 c reflected by the information recording surface 41 c are transmitted through the objective lens 56, the quarter-wave plate 54, converted into linearly polarized light that is 90 degrees different from the forward path, and then transmitted through the convex lens 82 and the concave lens 81. Then, it is reflected by the polarization beam splitter 52. The beams 70 a to 70 c reflected by the polarization beam splitter 52 are divided into two beams 72 and 74 by the beam splitter 87. Although not shown here, the beam 72 and the beam 74 include three beams 72a to 72c and 74a to 74c corresponding to the beams 70a to 70c, respectively. The light quantity ratio between the beam 72 and the beam 74 is 1: 9. The beam 72 is incident on the photodetector 31 through the detection lens 59 and the cylindrical lens 57 having a focal length f3 of 30 mm. Astigmatism is given to the beam 72 when passing through the cylindrical lens 57. When the beams 70a to 70c are focused on the information recording surface 41b or 41c, the beam 72 on the photodetector 31 is made to be a minimum circle of confusion. On the other hand, the beam 74 is incident on the photodetector 32 through the detection lens 84 and the cylindrical lens 85 having a focal length f4 of 30 mm. Astigmatism is also given to the beam 74 when passing through the cylindrical lens 85. When the beams 70a to 70c are focused on the information recording surface 41b or 41c, the beam 74 on the photodetector 32 is set to a focal line. The light source 1 is modulated at a high frequency of 400 MHz by the high frequency superimposing element 86, and the beam 70 emitted from the light source 1 has a plurality of wavelengths. By making the beam 70 emitted from the light source 1 have a plurality of wavelengths, the distribution of light and darkness due to interference is reduced.

  FIG. 3 schematically shows the relationship between the photodetector 31 and the beams 72a to 72c. The beams 72a to 72c are beams 72 divided by the beam splitter 87. The photodetector 31 has four light receiving portions 31a to 31d, and the light receiving portions 31a to 31d receive the beam 72a. A light receiving portion for receiving the beams 72b and 72c is not provided. The light receiving units 31a to 31d output current signals I31a to I31d corresponding to the received light amounts, respectively. An FE signal is obtained by using the signals I31a to I31d output from the photodetector 31. The detection method of the FE signal is an astigmatism method, that is, obtained by calculation of (I31a + I31c) − (I31b + I31d).

  Further, when the TE signal is detected by the phase difference method, the output timings of I31a to I31d may be compared and generated. Since a method of generating a TE signal by a phase difference method that is often used when using an optical storage medium having a reproduction-only information recording surface is generally well known, the description thereof is omitted here. Since the light quantity of the beam 72 is smaller than the light quantity of the beam 74, there may be a case where a sufficient signal-to-noise ratio cannot be obtained when the TE signal is generated by the phase difference method. In the case of an optical storage medium having a read-only information recording surface, the allowable range of the irradiated power level is wide. Therefore, by increasing the light amount of the beam 70 emitted from the light source 1, the TE signal generated by the phase difference method is increased. The signal to noise ratio can be improved.

  The optical storage medium 41 has two information recording surfaces 41b and 41c. When the information recording surface 41c collects the beams 70a to 70c and records or reproduces information, the information recording surface 41b also has a beam. Is reflected and then enters the photodetector 31. The beams 73a to 73c are beams that enter the photodetector 31 when the beams 70a to 70c are reflected by the information recording surface 41b. In the photodetector 31, only the beam 72 a which is a main beam is received by the photodetector 31. Therefore, the beam 72a and the beam 73a, the beam 72a and the beam 73b, and the beam 72a and the beam 73c are overlapped to generate a light / dark distribution due to interference. However, the light / dark distribution due to the interference is very small, and the FE signal is adversely affected. Stable focus control is possible without giving.

  FIG. 4 schematically shows the relationship between the photodetector 32 and the beams 74a to 74c. The beams 74a to 74c are beams 74 divided by the beam splitter 87. The photodetector 32 has six light receiving parts 32a to 32f, the light receiving parts 32a to 32b are the beam 74a, and the light receiving parts 32c to 32d are the light receiving parts 32a to 32f. The light receiving portions 32e to 32f receive the beam 74b and the beam 74c, respectively. The light receiving units 32a to 32f output current signals I32a to I32f corresponding to the received light amounts. A TE signal is obtained using the signals I32a to I32f output from the photodetector 32. The TE signal detection method is the DPP method, that is, obtained by the calculation of (I32a−I30b) −C · {(I32c + I32e) − (I32d + I32f)}. Here, C is a coefficient determined by the ratio of the diffraction efficiency of the zero-order diffracted light of the diffraction grating 83 and one first-order diffracted light. The FE signal and the TE signal are amplified and phase compensated to a desired level, and then supplied to actuators 91 and 92 for moving the objective lens 56 to perform focus and tracking control.

  The RF signal is obtained by the calculation of I32a + I30b. In the optical information apparatus according to the present embodiment, the beam 70 is divided into the beam 72 and the beam 74. However, the light quantity of the beam 72 is larger than the light quantity of the beam 74. When detecting a signal, the beam is received by four light receiving units, whereas in the present optical information apparatus, the beam is received by two small light receiving units. Therefore, the signal-to-noise ratio of the RF signal obtained by the present optical information device is about 3 to 6 dB better than that of the conventional optical information device, so that the optical information device can reproduce information with high reliability.

  FIG. 5 shows a configuration of a signal processing unit for generating a TE signal. The signals I32a and I32b output from the light receiving units 32a and 32b are subjected to differential calculation by the differential calculation unit 801. I32a-I32b, which are differentially calculated signals, are TE signals by the so-called push-pull method. When the TE signal is detected by a simple push-pull method, if the objective lens 56 is made to follow the tracking according to the eccentricity of the optical storage medium 41, the TE signal will change in offset according to the tracking tracking. In this signal processing unit, signals I32c and I32e output from the light receiving units 32c and 32e are added by an adding unit 802, and signals I32d and I32f output from the light receiving units 32d and 32f are added by an adding unit 803, respectively. The signals output from the adders 802 and 803 are subjected to a differential operation by a differential operation unit 804. The signal output from the differential operation unit 804 is input to the variable gain amplification unit 805 and amplified or attenuated to a desired signal strength. The amplification degree at this time is C. The signal output from the variable gain amplifying unit 805 has the same variation as the offset variation corresponding to the tracking tracking that the signal output from the differential operation unit 801 has. The differential operation unit 806 receives the signal output from the differential operation unit 801 and the signal output from the variable gain amplification unit 805 and performs a differential operation so that the signal output from the differential operation unit 801 is received. Reduces offset fluctuation according to tracking tracking. The signal output from the differential operation unit 806 outputs a TE signal with almost no offset fluctuation even if tracking is followed, but as it is, the reflectivity of the information recording surfaces 41b and 41c of the optical storage medium 41, the optical storage medium Since the signal intensity changes according to the change of the intensity of the beam irradiated to 41, the signal intensity is input to the dividing unit 808 so as to have a constant amplitude. The signals I32a to I32b output from the light receiving units 32a to 32b are added by the adding unit 807 and then input to the dividing unit 808 as a signal for division. The signal output from the adder 807 is a signal proportional to the reflectance of the information recording surfaces 41b and 41c of the optical storage medium 41 and the intensity of the beam irradiated to the optical storage medium 41, and the signal output from the divider is A TE signal having a desired intensity is obtained.

  The optical storage medium 41 has two information recording surfaces 41b and 41c. When the information recording surface 41c collects the beams 70a to 70c and records or reproduces information, the information recording surface 41b also has a beam. Is reflected and then enters the photodetector 32. The beams 75a to 75c are beams incident on the photodetector 32 when the beams 70a to 70c are reflected by the information recording surface 41b. Since the beam 70 is focused on the information recording surface 41c, the information recording surface 41b is largely defocused. Therefore, the beams 75 a to 75 c are also largely defocused on the photodetector 45. The photodetector 32 receives both the beam 74a as a main beam and the beams 74b and 74c as sub beams. Therefore, the beam 74b and the beam 75a, the beam 74c and the beam 75a, and the like overlap to produce a light / dark distribution due to interference, but the light / dark distribution due to the interference is extremely small compared to the change in the conventional optical pickup head device. . This is because when the beams 70a to 70c are focused on the information recording surface 41b or 41c, the beams 74a to 74c on the light detector 32 become focal lines. That is, when the direction in which the beams 74a to 74c are arranged on a virtual straight line on the surface of the photodetector 32 is the X direction and the direction orthogonal to the X direction is the Y direction, the size of the beams 74a to 74c in the X direction is large. Is smaller than the size in the Y direction. As the size of the beams 74a to 74c in the X direction is reduced, the amount of light per unit area in the beams 74a to 74c is increased, and the influence of light and darkness due to interference is reduced accordingly. When the diameter of the minimum circle of confusion of the beam on the photodetector of a general optical pickup head device is 100 μm and the size of the beams 74a to 74c in the Y direction is also 100 microns, the size of the beams 74a to 74c in the X direction Is about 5 μm. Therefore, the amount of light per unit area in the beams 74a to 74c is 20 times higher than the beam of the smallest circle of confusion having the same size in the Y direction. Of course, this is the case where the focal length f4 of the detection lens 84 is 30 mm. If the focal length f4 of the detection lens 84 is shortened, the size of the focal line in the X direction is further reduced, and the beam 74a. It is also possible to increase the amount of light per unit area in ˜74c and further reduce the influence of interference. In the present embodiment, the focal length f3 of the condensing lens 59 and the focal length f4 of the condensing lens 84 are set to the same 30 mm in order to reduce the types of parts by using common parts, but if necessary, It is possible to design an optical system with arbitrary values. In addition, since the light receiving portions 32a to 32f can be made small, the size of the photodetector 32 can be made small, and accordingly, an inexpensive optical pickup head device is obtained.

  FIG. 6 is a diagram illustrating a state when the TE signal obtained by the optical information device according to the present embodiment is observed with an oscilloscope. The amplitude TEpp and symmetry of the TE signal are very stable, and stable tracking control is possible.

  The size h1 in the X direction of the light receiving portions 32a to 32b that receive the beam 74a is smaller than the size h2 in the Y direction. This is possible because the size of the beams 74a to 74c in the X direction is smaller than that in the Y direction. Although depending on the optical design, h1 can be reduced to about 1/20 of h2. The distances between the beams 70a to 70c on the information recording surfaces 41b and 41c of the optical storage medium 41 are reduced by making the sizes of the beams 74a to 74c and the light receiving portions 32a to 32f in the X direction smaller than the sizes in the Y direction, respectively. Therefore, even when the optical storage medium 41 is eccentric, the fluctuation of the amplitude of the TE signal due to the eccentricity is reduced, and stable tracking control is possible. In the optical information apparatus of the present embodiment, the grating period of the diffraction grating 83 is set to be 2 to 5 times the grating period of the diffraction grating 58 in the conventional optical pickup head apparatus. Further, when assembling the optical information device, it is necessary to adjust the setting angle of the diffraction grating so that the beams 70a to 70c are at desired positions on the optical storage medium 41. The accuracy is greatly relaxed compared to the diffraction grating in the conventional optical pickup head device, and an optical information device with high productivity can be provided.

  The information recorded on the information recording surfaces 41b and 41c of the optical storage medium 41 is obtained by adding signals output from the light receiving units 32a and 32b. When the size of the light receiving portions 32a and 32b in the X direction is reduced, the capacitance parasitic on the light receiving portions 32a and 32b is reduced accordingly. When the light receiving portions 32a and 32b are configured by photodiodes, current is output from the light receiving portions 32a and 32b. When current signals output from the light receiving units 32a and 32b are converted into voltage signals using a transimpedance amplifier or the like, noise increases due to the parasitic capacitance of the light receiving units 32a and 32b. The smaller the capacitance parasitic on the light receiving portions 32a and 32b, the smaller the noise, and the optical information device of the present embodiment can reproduce information recorded on the information recording surfaces 41b and 41c with high reliability.

  The concave lens 81 and the convex lens 82 as spherical aberration correcting means are examples, and any general configuration such as a liquid crystal element can be applied.

(Embodiment 2)
FIG. 7 schematically shows a relationship between the photodetector 33 and the beams 74a to 74c as an example of another optical information device according to the present invention. By using the photodetector 33 instead of the photodetector 32 constituting the optical pickup head device 401, an optical information device can be constructed. The photodetector 33 has ten light receiving portions 33a to 33j and outputs signals I33a to I33j corresponding to the received light amounts. The light receiving units 33a to 33b receive the beam 74a, the light receiving units 33c to 33f receive the beam 74b, and the light receiving units 33g to 33j receive the beam 74c. That is, the light receiving units 33c to 33f correspond to 32c to 32d in the photodetector 32, and the light receiving units 33g to 33j correspond to 32e to 32f in the photodetector 32. For the calculation to obtain the TE signal, the photodetector 32 is used. What is necessary is just to calculate similarly the signal output from each light-receiving part corresponding to the case where it uses and the case where the photodetector 33 is used.

  By receiving the beams 74b to 74c with the four light receiving portions 33c to 33f and 33g to 33j, the positional relationship between the photodetector 33 and the beam 74 when assembling the optical pickup head device can be easily confirmed. By calculating (I33c + I33d) − (I33e + I33f), the positional relationship in the Y direction between the light receiving units 33c to 33f and the beam 74b is calculated by calculating (I33c + I33e) − (I33d + I33f) and X between the light receiving units 33c to 33f and the beam 74b. The positional relationship regarding the direction can be easily confirmed. The same applies to the light receiving portions 33g to 33j and the beam 74c. Since the positional relationship between the photodetector 33 and the beam 74 can be easily adjusted with high accuracy, even when the positional relationship between the photodetector 33 and the beam 74 is shifted due to a change with time, the positional accuracy between the photodetector 33 and the beam 74 can be increased. Since the adjustment has been made well, it is not easily affected by changes over time, and the deterioration of the detected TE signal is small. Therefore, the optical information device described in this embodiment is a highly reliable optical information device.

  When detecting the RF signal using the light receiving portions 33a and 33b, it is preferable from the viewpoint of maintaining a good signal-to-noise ratio that two light receiving portions receive the beam 74a. When the beam 74a is received by the four light receiving portions, the signal-to-noise ratio is deteriorated by 3 dB as compared with the case where the light is received by the two light receiving portions. Of course, when the signal-to-noise ratio has a margin, the beam 74a may be received by the four light receiving portions.

  In addition, since there is almost no gap between the beams 74a to 74c, even when only one of the light receiving portions 33c to 33f and the light receiving portions 33g to 33j is used as four light receiving portions, the beams 74a to 74c and the light are assembled when the optical information device is assembled. It is possible to adjust the positional relationship with the detector 33 with high accuracy.

(Embodiment 3)
FIG. 8 schematically shows a relationship between the photodetector 34 and the beams 74a to 74c as an example of another optical information apparatus according to the present invention. By using the photodetector 34 instead of the photodetector 32 constituting the optical pickup head device 401, an optical information device can be constructed. The photodetector 34 has 14 light receiving portions 34a to 34n, and outputs signals I34a to I34n corresponding to the received light amounts. The light receiving units 34a to 34b receive the beam 74a, the light receiving units 34c to 34h receive the beam 74b, and the light receiving units 34i to 34n receive the beam 74c, respectively. That is, the light receiving units 34c to 34h correspond to 32c to 32d in the photodetector 32, and the light receiving units 34i to 34n correspond to 32e to 32f in the photodetector 32. For the calculation to obtain the TE signal, the photodetector 32 is used. What is necessary is just to calculate similarly the signal output from each light-receiving part corresponding to the case where it uses and the case where the photodetector 34 is used.

  By receiving the beams 74b to 74c with the six light receiving portions 34c to 34h and 34i to 34n, respectively, the positional relationship between the photodetector 34 and the beam 74 when assembling the optical pickup head device can be easily confirmed. By calculating (I34c + I34d + I34e) − (I34f + I34g + I34h), the positional relationship in the Y direction between the light receiving units 34c to 34h and the beam 74b is calculated by calculating (I34c + I34f) − (I34e + I34h). The positional relationship regarding the direction can be easily confirmed. Further, here, by providing the light receiving portions 34d and 34g having a width h3 of 5 to 10 μm, the positional relationship between the condenser lens 84 and the photodetector 34 can be easily confirmed. If the distance between the condenser lens 84 and the photodetector 34 is adjusted so that the signals output from the light receiving portions 34d and 34g are maximized, the TE signal is least affected by interference. Although not described here, the same applies to the light receiving portions 34i to 34n and the beam 74c. Since the positional relationship between the photodetector 34 and the beam 74 and the positional relationship between the condensing lens 84 and the beam 74 can be adjusted easily and accurately, the positional relationship between the photodetector 34 and the beam 74 due to changes over time, and Even if the positional relationship between the condensing lens 84 and the beam 74 is deviated, since the optical information device is adjusted with high accuracy, it is not easily affected by changes over time, and the detected TE signal is less deteriorated. For this reason, the optical information device described in this embodiment is a highly reliable optical information device.

(Embodiment 4)
FIG. 9 schematically shows the relationship between the photodetector 35 and the beams 74a to 74c as an example of another optical information device according to the present invention. By using the photodetector 35 instead of the photodetector 32 constituting the optical pickup head device 401, an optical information device can be constructed. The photodetector 35 has eight light receiving portions 35a to 35h, and outputs signals I35a to I35h corresponding to the received light amounts. The light receiving units 35a to 35b receive the beam 74a, the light receiving units 35c to 35d receive the beam 74b, and the light receiving units 35e to 35f receive the beam 74c, respectively. That is, the light receiving portions 35c to 35d correspond to 32c to 32d in the photodetector 32, and the light receiving portions 35e to 35f correspond to 32e to 32f in the photodetector 32. For the calculation to obtain the TE signal, the photodetector 32 is used. What is necessary is just to calculate similarly the signal output from each light-receiving part corresponding to the case where it uses and the case where the photodetector 35 is used.

  By providing a light receiving portion 35g between the light receiving portions 35a to 35b and 35c to 35d and a light receiving portion 35h between the light receiving portions 35a to 35b and 35e to 35f, respectively, between the light receiving portions 35a to 35b and 35c to 35d, And the electrical isolation degree between the light-receiving parts 35a-35b and 35e-35f is raised. The width h4 of the light receiving portion 35g is selected to be about 1 to 10 μm. The same applies to the light receiving unit 35h. Depending on the width of the light receiving portions 35g and 35h, it is necessary to change the interval between the beams 74a to 74c on the photodetector 35. In this case, the period of the grating formed in the diffraction grating 83, the focusing lens What is necessary is just to design optical conditions, such as a focal distance f4, appropriately. A signal based on receiving the beam 72a by the light receiving portions 35a to 35b by increasing the electrical separation between the light receiving portions 35a to 35b and 35c to 35d and between the light receiving portions 35a to 35b and 35e to 35f. However, the degree of mixing with the signals output from the light receiving sections 35c to 35f is reduced, and a more stable TE signal can be detected.

(Embodiment 5)
FIG. 10 shows a configuration of a signal processing unit for generating a TE signal as an example of another optical information device according to the present invention. By using this signal processing unit instead of the signal processing unit in the optical information device described in Embodiment 1, the optical information device can be configured. The difference between the signal processing unit and the signal processing unit in the optical information device shown in Embodiment Mode 1 is that a sample and hold unit 809 is provided.

  FIG. 11 schematically shows the relationship between the data recorded on the information recording surface 41b or 41c and the recording power. Information is recorded on the information recording surface 41b or 41c as a mark row. Here, the mark is recorded with multi-pulses, and the power levels used are three levels P1 to P3. The power level P1 is used for cooling when forming the mark, and is 0.6 mW here. This is the same level as the power level used when reproducing the information recorded on the information recording surface 41b or 41c. The power level P2 is used for erasing and is 4.0 mW here. The power level P3 is used for forming the mark, and is 10.0 mW here. In the optical information device according to the present embodiment, the signal at the timing of the power level P1 is sampled and held by the sample and hold unit 809 to generate the TE signal. Even if an attempt is made to modulate the light source 1 at a high frequency of 400 MHz by the high frequency superimposing element 86 so that the beam 70 emitted from the light source 1 has a plurality of wavelengths, as the power level increases, a plurality of the light sources 1 are gradually increased. This is because it becomes difficult to provide a wavelength. By generating the TE signal using the beam at the timing of the power level P1, that is, the timing at which the power level is low, the influence of the light / dark distribution due to interference can be reduced and stable TE can be recorded even when information is recorded. A signal can be obtained.

(Embodiment 6)
FIG. 12 shows a configuration of an optical pickup head device 402 constituting an optical information device as an example of another optical information device according to the present invention. By using the optical pickup head device 402 instead of the optical pickup head device 401 in the optical information device described in Embodiment 1, the optical information device can be configured. The difference between the optical pickup head device 402 and the optical pickup head device 401 in the optical information device shown in the first embodiment is that a beam splitter 88 is used instead of the beam splitter 87 and a photodetector 36 is used instead of the photodetectors 31 to 32. It is using. The beam splitter 88 has two reflecting films 88a and 88b. The reflective film 88 a splits the incident beam 70 into two beams 72 and 74. The beam 72 is a beam that passes through the reflection film 88a, and the beam 74 is a beam that reflects the reflection film 88a. The light quantity ratio between the beams 72 and 74 is 1: 9. The beam 74 reflected by the reflecting film 88a is reflected by the reflecting film 88b, and the optical path is bent. The beams 72 and 74 pass through the detection lenses 59 and 84 and the cylindrical lenses 57 and 85, respectively, and then are received by the photodetector 36.

  FIG. 13 schematically shows the relationship between the photodetector 36 and the beams 72a to 72c and 74a to 74c. The photodetector 36 is made of one semiconductor substrate, has ten light receiving portions 36a to 36j, and outputs signals I36a to I36j corresponding to the received light amounts. The light receiving units 36a to 36b receive the beam 74a, the light receiving units 36c to 36d receive the beam 74b, the light receiving units 36e to 36f receive the beam 74c, and the light receiving units 36g to 36j receive the beam 72a, respectively. That is, the light receiving parts 36 a to 36 f correspond to the light receiving parts 32 a to 32 f in the light detector 32, and the light receiving parts 36 g to 36 j correspond to the light receiving parts 31 a to 31 d in the light detector 31, respectively. By using the photodetector 36, the size of the optical pickup head device can be reduced as compared with the case where the photodetector 31 and the photodetector 32 are used, thereby realizing a compact optical information device. can do.

  The embodiment described above is an example, and various forms can be adopted without departing from the gist of the present invention. Needless to say, various modifications can be made without departing from the spirit of the present invention, such as using an unpolarized optical system. Since the FE signal detection method other than the astigmatism method has not been described because it is not related to the gist of the present invention, the present invention has no limitation on the FE signal detection method, and the spot size detection method, Foucault method is not limited. Any ordinary FE signal detection method such as method can be used. The focal lengths f1 to f4 and the numerical aperture NA of the lens are not particularly limited, and the focal length may be determined as necessary.

  Although the case where the optical storage medium 41 has two information recording surfaces has been described, it goes without saying that the same effect can be obtained even when the optical storage medium has three or more information recording surfaces. Of course, the same applies to surfaces that reflect other beams, such as the surface of an optical storage medium.

  The same effect of the present invention can also be obtained when detecting a TE signal using a simple push-pull method.

  The present invention relates to an optical pickup head device for recording, reproducing, or erasing information on an optical storage medium for recording information with marks and spaces, and an optical information device, and an optical storage medium having a plurality of information recording surfaces. Even when used, it is possible to realize an optical information device that can reduce fluctuations in TE signal amplitude and record or reproduce information with high reliability.

The figure which shows the outline of a structure of the optical information apparatus of Embodiment 1 of this invention. The figure which shows the structure of the optical pick-up head apparatus which comprises the optical information apparatus of Embodiment 1 of this invention. The figure which shows the relationship between the track | truck and beam on the optical storage medium in the optical information apparatus of Embodiment 1 of this invention. The figure which shows the relationship between the photodetector and beam which comprise the optical pick-up in the optical information apparatus of Embodiment 1 of this invention. The figure which shows the structure of the signal processing part which comprises the optical information apparatus of Embodiment 1 of this invention. The figure which shows the mode of TE signal obtained with the optical information apparatus of Embodiment 1 of this invention The figure which shows the relationship between the photodetector and beam which comprise the optical pick-up in the optical information apparatus of Embodiment 2 of this invention. The figure which shows the relationship between the photodetector and beam which comprise the optical pick-up in the optical information apparatus of Embodiment 3 of this invention. The figure which shows the relationship between the photodetector and beam which comprise the optical pick-up in the optical information apparatus of Embodiment 4 of this invention. The figure which shows the structure of the signal processing part which comprises the optical information apparatus of Embodiment 5 of this invention. The figure which shows the relationship between the recording data and sampling timing in the optical information apparatus of Embodiment 5 of this invention The figure which shows the structure of the optical pick-up head apparatus which comprises the optical information apparatus of Embodiment 6 of this invention. The figure which shows the relationship between the photodetector and beam which comprise the optical pick-up in the optical information apparatus of Embodiment 6 of this invention. The figure which shows the structure of the optical pick-up head apparatus which comprises the conventional optical information apparatus. The figure which shows the relationship between the track | truck and beam on the optical storage medium in the conventional optical information apparatus. The figure which shows the relationship between the photodetector and light which comprise the optical pick-up in the conventional optical information apparatus. The figure which shows the mode of TE signal obtained with the conventional optical information apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 4,401-402 Optical pick-up 5 Transfer controller 6 Motor 7 1st control means 8 Amplifier 9 2nd control means 10 Demodulation means 11 Detection means 12 System control means 14 Output means 30-36 Photodetectors 30a- 30h, 31a to 31d, 32a to 32f, 33a to 33j, 34a to 34n, 35a to 35h, 36a to 36j Light receiving unit 41 Optical storage medium 41 Transparent substrate 41b, 41c Information recording surface 52 Polarizing beam splitter 53 Collimating lens 54 4 minutes 1 wavelength plate 55 aperture 56 objective lens 57,85 cylindrical lens 58,83 diffraction grating 59,84 condenser lens 70,70a-70c, 71a-71c, 72,72a-72c, 73a-73c, 74,74a-74c 75a-75c Beam 81 Concave lens 82 Lens 86 high-frequency superposition element 87, 88 the beam splitter 91 through 93 actuators 801,804,806 differential arithmetic operation portion 802,803,807,813 addition unit 805,810,812 variable gain amplifying unit 808 divider 809 sample-and-hold unit

Claims (9)

A light source that emits a light beam; a diffracting unit that receives the beam emitted from the light source and generates a plurality of diffracted beams of zero order and first order; and a plurality of diffracted beams from the diffracting unit Condensing means for condensing on the optical storage medium, and the plurality of diffracted beams collected on the optical storage medium are reflected by the optical storage medium and reflected by the optical storage medium a beam splitting means for splitting the beam receiving the beam has been receiving the plurality of diffracted beams branched by the branching means, provided with a light detecting means for outputting a signal corresponding to the received light amount, the light detection The means includes a plurality of light receiving portions, and the 0th-order diffracted light among the plurality of diffracted beams generated by the diffracting means is used as a main beam, and the first and second order diffracted lights generated by the diffracting means are the first. Sub-beam and second The sub-beams, wherein the main beam and the first sub-beam the second sub-beam are respectively received by the plurality of light receiving portions, irradiating the condensed beam by the focusing means to a desired location of the optical storage medium The tracking error signal used when tracking control is performed is a differential push obtained by differentially calculating a signal output from a light receiving unit that receives the main beam, the first sub beam, and the second sub beam. The information recording is detected by a pull method, wherein the optical storage medium has a plurality of information recording surfaces, and the plurality of diffraction beams are condensed when information is read or written out of the plurality of information recording surfaces. A light collecting surface, an information recording surface different from the light collecting surface is a non-light collecting surface, and the plurality of diffracted beams are reflected by the light collecting surface, and then When the information received on the light collecting surface and recorded on the light collecting surface is read out, and when the information recorded on the light collecting surface is read out, the plurality of diffracted beams are reflected also on the non-light collecting surface and then the light detection is performed. The plurality of diffracted beams incident on the means and reflected by the non-condensing surface are largely defocused on the light detecting means, and the first sub-beam and the second sub-beam reflected by the condensing surface And the main beam reflected by the non-condensing surface, and the main beam, the first sub-beam, and the second sub-beam reflected by the condensing surface are on the light detection means. In a surface that receives the plurality of diffracted beams that are substantially aligned on one virtual straight line and reflected by the light collecting surface of the light detection means, the direction of the virtual straight line is a first direction, The first direction is straightforward When the direction orthogonal to the second direction, the magnitude of the first direction of the second sub beam and before Symbol first sub-beam in the converging surface in reflected the said light detecting means on the said It has a second direction of smaller substantially focal line than the size, the optical pick-up head, wherein the this. The main beam, the first sub beam, and the second sub beam are received by a plurality of light receiving units, respectively. The plurality of light receiving units that receive the main beam are defined as a first light receiving unit group, and the first sub beam is used as the first sub beam. A plurality of light receiving units that receive light are defined as a second light receiving unit group, a plurality of light receiving units that receive the second sub-beam are defined as a third light receiving unit group, and the first light receiving unit group is larger in the first direction. The optical pickup head device according to claim 1, wherein the height is smaller than a size in the second direction. The size of the second light receiving unit group in the first direction is smaller than the size of the second direction, and the size of the third light receiving unit group in the first direction is larger than the size of the second direction. The optical pickup head device according to claim 2 , wherein the optical pickup head device is small. The optical pickup head device according to any one of claims 1 to 3 , further comprising a light receiving portion in addition to the first to third light receiving portion groups. The light receiving section is provided between the first light receiving section group and the second light receiving section group and between the first light receiving section group and the third light receiving section group, respectively. 5. An optical pickup head device according to item 4 . The second detection part group or the third group of light receiving portions is three or more optical pickup head apparatus according to any one of claims 1 to 5, characterized in that it consists of the light receiving unit. The optical pickup head device according to claim 6, wherein the second light receiving unit group or the third light receiving unit group includes six light receiving units. An optical pickup head apparatus according to any one of claims 1 to 7, the optical storage medium, a drive unit for changing relative positions of the optical pick-up head, is outputted from the optical pick-up head An optical information device comprising: an electric signal processing unit that receives a signal and performs an operation to obtain desired information. Tracking error signal generating means for generating a tracking error signal that is a signal for performing control to irradiate a beam onto a desired track, and when recording information on the information recording surface of the information recording medium, The diffracted beam has a first power level and a second power level, the first power level being less than the second power level, and the light source has a high frequency at the first power level. The tracking error signal generation unit generates the tracking error signal after sampling and holding the signal output from the light detection unit at the timing of the first power level. 8. An optical information device according to 8 .

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