JP6064760B2 - Optical pickup device and optical disk device - Google Patents

Description

  The present invention relates to an optical pickup device that forms a focused spot on an optical disc, and an optical disc device including the same.

  2. Description of the Related Art Conventionally, optical pickup devices that are compatible with multilayer optical disks have been widely used. Such an optical pickup device forms a condensing spot on a predetermined target layer and receives a reflected light to obtain a TE (tracking error) signal or the like. The TE signal is used for position adjustment (tracking servo) of the objective lens.

  When receiving reflected light from an optical disk having a multilayer structure, it is important to suppress as much as possible the influence of other layer stray light (light reflected from a layer other than the target layer) that becomes noise. For this reason, for an optical pickup device compatible with an optical disk having a multilayer structure, a method that is resistant to other-layer stray light (not easily affected by other-layer stray light) is often selected from various TE signal generation methods.

  In general, the condensing spot has an elliptical shape, and there is a direction (light spot direction) in which the diameter is maximum. When a method strong against stray light from other layers is selected as the TE signal generation method, generally, the focused spot direction is set to be the radial direction of the optical disc. In consideration of deviations in the emission angle and emission angle of the laser diode that is the light source, the balance deviation when the TE signal is obtained is suppressed as the focused spot direction is closer to the radial direction of the optical disc, which is suitable for the generation of the TE signal. The main reason is.

JP 2012-84200 A

  However, if the direction of the focused spot is the radial direction of the optical disk, for example, 2T resolution (resolution with respect to the minimum unit frequency such as an information read signal) is reduced, jitter performance is deteriorated, and it is difficult to properly reproduce the optical disk. Become. In order to solve such a problem, it may be possible to add components such as a RIM correction element (an element that corrects the light intensity distribution of laser light from an elliptical shape to a circular shape), but the manufacturing cost increases accordingly. End up.

  Depending on the TE signal generation method, for example, the reflected light from the optical disk may be divided into 0th-order diffracted light and ± 1st-order diffracted light, and a TE signal may be generated according to the intensity of these diffracted lights. . In such a case, especially when the DC component of the ± 1st-order diffracted light is strongly influenced by other layer stray light, the TE signal is often not generated properly, and it is difficult to properly reproduce the optical disc. Become.

  SUMMARY OF THE INVENTION In view of the above-described problems, the present invention provides an optical pickup device that makes it easy to appropriately reproduce an optical disc while suppressing the addition of components as much as possible even when other-layer stray light occurs, and an optical disc device including the same The purpose is to provide.

  An optical pickup device according to the present invention includes a condensing spot forming unit for irradiating an information recording surface of an optical disc with laser light to form a condensing spot, and reflected light reflected from the condensing spot as main diffracted light and sub-light. A diffraction grating that divides into diffracted light, a 0th light-receiving unit that receives the main diffracted light, a first light-receiving unit that receives a first region light including a PP component of the sub-diffracted light, and a DC of the sub-diffracted light A second light receiving unit that receives the second region light including the component, and a TE signal generation unit that generates a tracking error signal based on at least the intensity of the light received by the second light receiving unit, the first light receiving unit, The second light receiving unit is disposed at a position away from the 0th light receiving unit, and the focused spot forming unit is configured such that the focused spot direction where the diameter of the focused spot is maximum is shifted from the radial direction of the optical disc. Shape A configuration that is. According to this configuration, even when other-layer stray light is generated, it becomes easy to appropriately reproduce the optical disc while suppressing the addition of components and the like as much as possible.

  More specifically, the condensing spot forming unit forms the condensing spot on the information recording surface of a predetermined target layer in the optical disc having a multilayer structure, and includes a first light receiving spot. The part and the second light receiving part may be arranged at a position where the intensity of the other-layer stray light reflected from a layer other than the target layer is weaker than the position of the 0th light receiving part. The second light receiving unit may be arranged at a position where the intensity of the other layer stray light is weaker than the position of the first light receiving unit. According to this configuration, it is possible to eliminate the influence of other-layer stray light as much as possible in detecting the intensity of the DC component of the sub-diffraction light.

  More specifically, the diffraction grating divides the reflected light into the main diffracted light and the sub diffracted light, and emits the sub-diffracted light in the first region. It is good also as a structure formed so that it may radiate | emit with the form divided | segmented into light and 2nd area | region light. More specifically, the main diffracted light may be zero-order diffracted light by the diffraction grating, and the sub-diffracted light may be ± first-order diffracted light by the diffraction grating. .

  More specifically, the above configuration may be configured such that the angle between the focused spot direction and the track direction of the optical disc is within a range of 55 ± 5 deg. More specifically, the above-described configuration may be configured such that the angle is adjusted so that the angle falls within the range of 55 ± 5 deg by adjusting the maximum radiation angle direction of the laser light.

  More specifically, as the above configuration, the angle adjustment is performed by adjusting the maximum radiation angle direction within a range of ± 1.4 deg in the rotation direction around the laser beam emission direction as an axis. Also good. According to this configuration, the angle adjustment can be achieved only by performing a relatively slight adjustment.

  An optical disc apparatus according to the present invention includes the optical pickup device having the above-described configuration, and reads data from the optical disc or records data on the optical disc. According to this configuration, it is possible to enjoy the advantages of the optical pickup device having the above configuration.

  According to the optical pickup device of the present invention, even when stray light from other layers is generated, it becomes easy to appropriately reproduce the optical disc while suppressing the addition of components as much as possible. Further, according to the optical disc apparatus according to the present invention, it is possible to enjoy the advantages of the optical pickup apparatus according to the present invention.

It is a block diagram of the disc reproducing | regenerating apparatus concerning this embodiment. It is explanatory drawing regarding each light reception sensor which concerns on this embodiment. It is another explanatory drawing regarding the said light reception sensor. It is explanatory drawing regarding the shape of a condensing spot. It is explanatory drawing regarding the form of a laser beam. It is a graph regarding the relationship between angle (theta) and 2T resolution. It is a graph regarding the relationship between 2T resolution and i-MLSE.

  Embodiments of the present invention will be described below with reference to the drawings.

[Configuration of optical disc playback apparatus]
FIG. 1 is a configuration diagram of an optical disk reproducing apparatus 5 (one form of optical disk apparatus) according to the present embodiment. As shown in the figure, the optical disk reproducing device 5 includes an optical pickup device 1 and a reproduction signal processing circuit 3.

  The optical pickup device 1 corresponds to an optical disk 9 having a multilayer structure. In other words, the optical pickup device 1 is configured such that a multi-layered optical disk 9 is set and the optical disk 9 is appropriately irradiated with laser light. The set optical disk 9 is rotated by a spindle motor (not shown). Note that, as the optical disk having a multilayer structure to which the optical pickup device 1 corresponds, for example, an optical disk conforming to the BD-XL standard is applicable.

  The optical pickup device 1 includes a laser diode 11, a beam splitter 12, a collimator lens 13, a mirror 14, a front monitor IC 15, a lens actuator 16, a grating element GR, a cylindrical lens 17, a PDIC 18, an FE detection unit 19a, a TE detection unit 19b, and a focus. A control unit 20a, a tracking control unit 20b, and the like are provided.

  The laser diode 11 is formed so as to output laser light having a predetermined wavelength. The intensity of the output light from the laser diode 11 can be controlled by the front monitor IC 15.

  The beam splitter 12 reflects the light received from the laser diode 11 in a direction having an angle of approximately 90 degrees, and enters the collimating lens 13. The collimating lens 13 converts the light received from the beam splitter 12 into parallel light and makes it incident on the mirror 14.

  The mirror 14 reflects the light received from the collimating lens 13 and makes it incident on the objective lens 16 a provided in the lens actuator 16. The mirror 14 transmits a part of the light received from the collimator lens 13 and enters the front monitor IC 15. For example, a quarter-wave plate may be provided between the mirror 14 and the objective lens 16 a so that the reflected light from the optical disk 9 does not return to the laser diode 11.

  The front monitor IC 15 generates an electric signal corresponding to the intensity of incident light, and controls the intensity of the output light of the laser diode 11 so that the electric signal is kept constant. That is, the front monitor IC 15 realizes automatic power control with respect to the intensity of the output light of the laser diode 11 so as to maintain the intensity of incident light at a predetermined target value.

  The lens actuator 16 is provided with an objective lens 16a at a movable portion thereof, and drives the objective lens 16a in a focus direction, a tracking direction, or the like. The driving of the objective lens 16a is controlled by the focus control unit 20a, the tracking control unit 20b, and the like.

  The lens actuator 16 drives the objective lens 16a so that the light incident on the objective lens 16a from the mirror 14 strikes the information recording surface of the target layer. The “target layer” is a layer determined in advance in the optical disc reproducing device 5 as a layer on which a focused spot is to be formed among a plurality of layers of the optical disc 9. Usually, one layer from which information is read or written corresponds to the target layer.

  Since the objective lens 16a is driven as described above, the light incident on the objective lens 16a from the mirror 14 strikes the information recording surface of the target layer and is reflected. As a result, a focused spot by the laser beam is formed on the information recording surface of the target layer. Then, the light reflected by the information recording surface of the target layer travels back through the objective lens 16a, the mirror 14, the collimating lens 13, and the beam splitter 12, passes through the beam splitter 12, and enters the grating element GR.

  The grating element GR divides light incident from the beam splitter 12 (reflected light from the information recording surface of the optical disk 9) into 0th order diffracted light and ± 1st order (both −1st order and + 1st order) diffracted light. Then exit. Note that the grating element GR is formed so that ± first-order diffracted light is emitted in a form divided into first region light and second region light. The first region light is light including the PP component (push-pull component) of ± 1st order diffracted light, and the second region light is DC component (DC component of ± 1st order diffracted light, which depends on the light. Light corresponding to the offset of the signal).

  The grating element GR is formed so as to separately emit 0th-order diffracted light, first-order diffracted light of the first region, and second-order light of ± 1st-order diffracted light. More specifically, these lights are emitted from the grating element GR through the cylindrical lens 17 in the direction of incidence on the corresponding light receiving sensors (described later in detail).

  The 0th-order diffracted light emitted from the grating element GR, the first region light of ± 1st order diffracted light, and the second region light of ± 1st order diffracted light enter the PDIC 18 through the cylindrical lens 17. In addition, as shown in FIG. 2, the PDIC 18 has five light receiving sensors (18a to 18e) separately.

  The light receiving sensor 18 a is a light receiving sensor that receives 0th-order diffracted light, and is disposed at a position where this light enters from the cylindrical lens 17. The light receiving sensor 18 b is a light receiving sensor that receives the first region light of the + 1st order diffracted light, and is disposed at a position where the light enters from the cylindrical lens 17. The light receiving sensor 18 c is a light receiving sensor that receives the first region light of the −1st order diffracted light, and is disposed at a position where the light enters from the cylindrical lens 17.

  The light receiving sensor 18 d is a light receiving sensor that receives the second region light of the + 1st order diffracted light, and is disposed at a position where this light is incident from the cylindrical lens 17. The light receiving sensor 18 e is a light receiving sensor that receives the second region light of the −1st order diffracted light, and is disposed at a position where the light enters from the cylindrical lens 17.

  Each light receiving sensor (18a to 18e) is provided with one or a plurality of photodiodes, and an electric signal corresponding to the intensity of received light is generated for each of the photodiodes.

  That is, the light receiving sensor 18a generates and outputs an electric signal Sa corresponding to the intensity of the 0th-order diffracted light. The light receiving sensor 18b generates and outputs an electric signal Sb corresponding to the intensity of the first region light of the + 1st order diffracted light. The light receiving sensor 18c generates and outputs an electric signal Sc corresponding to the intensity of the first region light of the −1st order diffracted light. The light receiving sensor 18d generates and outputs an electric signal Sd corresponding to the intensity of the second region light of the + 1st order diffracted light. The light receiving sensor 18e generates and outputs an electric signal Se corresponding to the intensity of the second region light of the −1st order diffracted light.

  Since the optical disk 9 has a multilayer structure, not only the reflected light reflected from the target layer but also the light reflected from the layers other than the target layer (stray light from other layers) is generated when the optical disk 9 is irradiated with laser light. To PDIC18. How the generated other layer stray light spreads depends on the specific configuration of the optical pickup device 1 and the like.

  If a specific configuration or the like of the optical pickup device 1 is specified, it is possible to grasp in advance the intensity distribution of the other layer stray light in the vicinity of the PDIC 18 by, for example, experiments or calculations. In the present embodiment, it is assumed that the intensity of the other layer stray light extending in the region SR shown in FIG. 2 is higher than that outside the region SR.

  Further, regarding the arrangement of the light receiving sensors for receiving ± first order diffracted light, the light receiving sensors (18b, 18c) for receiving the first region light and the light receiving sensors (18d, 18e) for receiving the second region light are shown in FIG. As shown, it is disposed at a position away from the light receiving sensor (18a) that receives the 0th-order diffracted light.

  More specifically, the light receiving sensor (18a) that receives the 0th-order diffracted light is disposed in the region SR, but the light receiving sensors (18b, 18c) that receive the first region light and the second region light. The light receiving sensors (18d, 18e) for receiving the light are arranged outside the region SR. That is, each of the light receiving sensors (18b to 18e) is disposed at a position where the intensity of the other layer stray light is weaker than the position of the light receiving sensor (18a). Furthermore, the light receiving sensors (18d, 18e) that receive the second region light are arranged at positions where the intensity of the stray light in the other layer is weaker than the positions of the light receiving sensors (18b, 18c) that receive the first region light. Yes.

  The light receiving sensors (18d, 18e) are arranged in various forms, including a form in which the light receiving sensors (18d, 18e) are arranged at a predetermined angle from the arrangement direction of the other light receiving sensors so that the influence of stray light from other layers is avoided as much as possible. obtain. For example, each light receiving sensor (18a to 18e) can be arranged at a position as shown in FIG. The intensity of the other-layer stray light that extends into the region SR ′ shown in FIG. 3 is higher than that outside the region SR ′. Further, for example, the light receiving sensors (18d, 18e) may be arranged at positions indicated by P1 and P2 in FIG.

  With the configuration described above, the PDIC 18 can detect the intensities of the 0th-order diffracted light, the PP component of the ± 1st-order diffracted light, and the DC component of the ± 1st-order diffracted light. Further, according to the PDIC 18, particularly, when detecting the intensity of the DC component of the ± 1st-order diffracted light, the influence of the other layer stray light is eliminated as much as possible.

  Returning to FIG. 1, the electrical signals (Sa to Se) generated by the light receiving sensors (18a to 18e) are sent to the FE detection unit 19a and the TE detection unit 19b. The electrical signal Sa generated by the light receiving sensor 18a (a signal including information recorded on the information recording surface of the target layer) is also sent to the reproduction signal processing circuit 3.

  The FE detection unit 19a generates an FE signal (focus error signal) based on the electrical signal received from the PDIC 18. This FE signal corresponds to a signal representing a detection result of a focus error (shift in the focus direction of the focused spot). As a method for generating the FE signal, any one of various methods that enable appropriate generation of the FE signal, including known ones, can be adopted. The FE signal generated by the FE detection unit 19a is sent to the focus control unit 20a.

  The TE detector 19b generates a TE signal (tracking error signal) based on the electric signal received from the PDIC 18. This TE signal corresponds to a signal representing a detection result of a tracking error (shift in the tracking direction of the focused spot). The TE signal generated by the TE detection unit 19b is sent to the tracking control unit 20b.

  Since the optical pickup device 1 is compatible with the optical disk 9 having a multilayer structure, the TE detection unit 19b is set to generate a TE signal by a generation method that is resistant to other-layer stray light (not easily affected by other-layer stray light). Has been. The TE detector 19b generates a TE signal based on each electrical signal including the electrical signal Sd and the electrical signal Se (a signal corresponding to the intensity of the DC component of ± first-order diffracted light). As a method for generating such a TE signal, any one of various methods including known ones such as the 1Beam method, the 1BeamPP method, or the 1BeamDPP method is applicable.

Further, as described above, in the detection of the intensity of the DC component of the ± 1st-order diffracted light, the influence of stray light from other layers is eliminated as much as possible. Therefore, the TE detection unit 19b can generate the TE signal more appropriately as much as the influence of the other layer stray light is eliminated. The TE signal is generated, for example, according to the following equation (1).
TE signal = AC component−k × DC component
= (Sb-Sc) -k (Sd-Se) (1) (where 1 <k <3)
Therefore, when other layer stray light enters the DC component side, appropriate generation of the TE signal is likely to be hindered. For example, there arises a problem that a balance shift occurs when obtaining a TE signal at the time of lens shift, and a problem that a noise component leaks when other layer stray light and signal light interfere to deteriorate the quality of the TE signal. In the present embodiment, the light receiving sensors (18d, 18e) that receive the second region light are arranged at positions where the intensity of the other layer stray light is weaker than the position of the light receiving sensors (18b, 18c) that receive the first region light. Therefore, it is easy to suppress such problems.

  The focus control unit 20a generates a signal for controlling the driving of the lens actuator 16 based on the FE signal, and outputs the signal to execute focus control. The focus control is control (focus servo) for adjusting the position of the objective lens 16a so that the laser beam is focused on the information recording surface of the target layer.

  The tracking control unit 20b generates a signal for controlling the driving of the lens actuator 16 based on the TE signal, and outputs the signal to execute tracking control. The tracking control is control (tracking servo) for adjusting the position of the objective lens 16a so that the focused spot of the laser beam follows the track of the target layer.

  The reproduction signal processing circuit 3 performs various types of processing (such as demodulation processing) on the electric signal Sa received from the PDIC 18 and generates a video signal or the like based on the electric signal. The generated signal is output to a display or the like (not shown) provided in the optical disc playback apparatus 5 and used for video display or the like. As described above, the optical disk reproducing device 5 reads data from the optical disk 9 by using the optical pickup device 1.

  The optical pickup device 1 may be provided in, for example, an optical disc recording device in addition to the optical disc reproducing device. In this case, the optical disc recording apparatus is configured to perform data recording on the optical disc 9 using the optical pickup device 1.

[Condensing spot direction]
As described above, the optical pickup device 1 forms a condensing spot on the information recording surface of the target layer of the optical disc 9, and obtains reflected light reflected from the condensing spot, thereby reproducing the optical disc 9, generating a TE signal, and the like. Make it possible.

  FIG. 4 illustrates the shape of the focused spot SP formed on the optical disc 9. As shown in this figure, the shape of the focused spot SP is generally elliptical due to the deviation of the radiation angle of the laser light emitted from the laser diode 11.

  For this reason, there is a direction in which the diameter of the condensed spot SP is maximum (referred to as a “condensed spot direction”). The performance and the like of the optical pickup device 1 change depending on the angle θ between the focused spot direction and the track direction of the optical disk 9. The track direction is the direction in which the track at the focused spot extends (the circumferential direction of the optical disk 9).

  Therefore, the optical pickup device 1 can adjust the angle θ by adjusting the inclination of the laser diode 11. This point will be described below with reference to FIG.

  FIG. 5 schematically shows the form of laser light emitted from the laser diode 11. As shown in the figure, the laser beam is not completely parallel to the emission direction (optical axis direction) and has a certain radiation angle. This radiation angle is biased, and the direction of the focused spot is determined by the direction in which the radiation angle is maximum (maximum radiation angle direction). The maximum radiation angle direction is determined by the inclination of the laser diode 11 (the position in the rotation direction about the laser beam emission direction).

  The inclination of the laser diode 11 can be adjusted when the laser diode 11 is attached to the optical pickup device 1 or after it is attached. This adjustment can be performed while monitoring the direction of the focused spot and the track direction of the optical disk 9. According to the optical pickup device 1, it is possible to adjust the inclination of the laser diode 11 (in the direction of the maximum radiation angle of laser light) so that the angle θ becomes a desired value.

  Here, the target value in the adjustment of the angle θ will be described. Considering the deviation of the emission angle and emission angle of the laser diode 11, the closer the angle θ is to 90 deg (the angle at which the focused spot direction is the radial direction of the optical disk 9), the more the intensity distribution of the focused spot on the photodiode is The characteristics are gentle with respect to the lens shift direction (disk radial direction). For this reason, a balance shift or the like when obtaining a TE signal at the time of lens shift or the like is suppressed, and a state suitable for generation of a TE signal is obtained. Therefore, from this viewpoint, it is desirable that the angle θ is as close to 90 ° as possible.

  FIG. 6 is a graph showing the relationship between the angle θ and the 2T resolution. As shown in this figure, the 2T resolution decreases as the angle θ approaches 90 degrees. In order to maintain the good performance of the optical pickup device 1, it is desirable to ensure 2T resolution of at least 9%. Therefore, according to this viewpoint, it is desirable that the angle θ is set to 60 deg as an upper limit.

  FIG. 7 is a graph showing the relationship between 2T resolution and BD-XL standard i-MLSE (an index indicating the degree of jitter). As shown in the figure, the jitter performance deteriorates as the 2T resolution decreases. Therefore, if the angle θ is too large, there is a problem with jitter performance, and it becomes difficult to properly reproduce the optical disk 9. In particular, when the angle θ is set near 90 deg, such a problem becomes serious.

  Considering the above points comprehensively, it is desirable to adjust the angle θ to a value as large as possible within a range not exceeding 60 deg. In practice, an adjustment error may occur due to various factors. Therefore, it is desirable to allow a general allowable error of 5 deg and set the target value in the adjustment of the angle θ to 55 deg.

  In this case, the angle θ can be set within the range of 55 ± 5 deg by keeping the adjustment error within the allowable error range. Thus, the optical pickup device 1 in which the angle θ is set does not prevent the proper generation of the TE signal, and the 2T resolution and jitter performance are relatively good.

  Further, in order to easily adjust the inclination of the laser diode 11, it is desirable that the initial state of the inclination of the laser diode 11 is considered so that the angle θ is close to 55 deg from the beginning. If it becomes like this, it will become possible to adjust angle (theta) in the range of 55 +/- 5deg only by finely adjusting the inclination of the laser diode 11. FIG. Therefore, the work for adjusting the angle θ is simplified.

  As a guide, the tilt of the laser diode 11 (maximum radiation angle direction of the laser light) is ± 1.4 deg (balance deviation when obtaining the TE signal at the time of lens shift) in the rotation direction with the laser light emission direction as an axis. It is desirable that the angle θ is adjusted within the range of 55 ± 5 deg by adjusting within the range of the range that is expected to be an allowable amount. In the optical pickup device 1, the initial state of the inclination of the laser diode 11 is set so that the angle θ can be adjusted in this way.

  Note that the target value in the adjustment of the angle θ can be set to another value according to various circumstances in addition to the 55 deg described above. Even in this case, if the angle θ is deviated from 90 deg (the condensing spot direction is deviated from the radial direction of the optical disc 9), a problem that the reproduction of the optical disc 9 is hindered can be relatively suppressed. Further, the laser diode 11 may be set so that the position of the laser diode 11 can be adjusted not only in the rotation direction around the laser beam emission direction but also in other directions.

[Others]
As described above, the optical pickup device 1 is configured to irradiate the information recording surface of the optical disc 9 with laser light to form a focused spot (a focused spot forming section), and reflected light reflected from the focused spot. A grating element GR (diffraction grating) that divides the zero-order diffracted light (main diffracted light) and ± first-order diffracted light (sub-diffracted light), a zeroth light-receiving unit that receives the zeroth-order diffracted light, A first light-receiving unit that receives first region light including the PP component of ± first-order diffracted light, a second light-receiving unit that receives second region light including the DC component of ± first-order diffracted light, and at least first And a TE detection unit 20a that generates a TE signal based on the intensity of light received by the two light receiving units.

  The condensed spot forming unit mainly corresponds to an optical system from the laser diode 11 to the objective lens 16a. The 0th light receiving part corresponds to the light receiving sensor 18a, the first light receiving part corresponds to the light receiving sensor (18b, 18c), and the second light receiving part corresponds to the light receiving sensor (18d, 18e). Further, diffracted light other than the 0th order may be used as the main diffracted light, and diffracted light other than ± 1st order may be used as the sub-diffracted light.

  The first light receiving unit and the second light receiving unit are arranged at positions away from the 0th light receiving unit. When arranged in this way, it is easy to arrange the first light receiving part and the second light receiving part at a position that is less susceptible to the effects of other-layer stray light than the 0th light receiving part. The second light receiving unit is disposed at a position away from the first light receiving unit. When arranged in this way, the second light receiving part is less susceptible to the effects of stray light from other layers, compared to the general case where the first light receiving part and the second light receiving part are not separated (almost at the same position). Easy to place in position. For example, even if the first light receiving unit is inevitably disposed in a region that is susceptible to the effects of stray light from other layers due to restrictions on the configuration of the optical pickup device, the second light receiving unit is disposed outside that region. Is easy.

  The condensing spot forming portion is formed so that the condensing spot direction where the diameter of the condensing spot is maximum is shifted from the radial direction of the optical disc 9 (non-perpendicular to the track of the optical disc 9). Yes. Since the optical pickup device 1 has these characteristics, even when stray light from other layers is generated, it is easy to appropriately reproduce the optical disc 9 while suppressing the addition of components such as the RIM correction element as much as possible. By suppressing the addition of parts as much as possible, it is possible to reduce the manufacturing cost accordingly.

  The condensing spot forming section is for forming a condensing spot on the information recording surface of the target layer in the optical disk 9 having a multilayer structure. The second light receiving unit is arranged at a position where the intensity of the other layer stray light reflected from the layer other than the target layer is weaker than the position of the first light receiving unit. Therefore, according to the optical pickup device 1, it is possible to eliminate the influence of stray light from other layers as much as possible in detecting the intensity of the DC component of ± first-order diffracted light.

  The grating element GR divides the reflected light reflected from the focused spot into a 0th-order diffracted light and a ± 1st-order diffracted light, and emits the first region for the ± 1st-order diffracted light. It is formed so as to be emitted in a form divided into light and second region light. However, instead of providing the grating element GR formed in this way, an element that divides the reflected light into 0th-order diffracted light and ± 1st-order diffracted light, and ± 1st-order diffracted light into the first region light and the first-order diffracted light. The element that divides into two regions of light may be provided separately.

  Further, in the optical pickup device 1, the angle θ between the direction of the focused spot and the track direction of the optical disc 9 is in the range of 55 ± 5 deg. More specifically, the optical pickup device 1 is angle-adjusted so that the angle θ is in the range of 55 ± 5 deg by adjusting the maximum radiation angle direction of the laser light. Therefore, according to the optical pickup device 1, the 2T resolution and jitter performance are relatively good without preventing the proper generation of the TE signal.

  Further, the optical pickup device 1 adjusts the maximum radiation angle direction of the laser beam within the range of ± 1.4 deg in the rotation direction around the laser beam emission direction, so that the angle θ is within the range of 55 ± 5 deg. Adjusted. Therefore, according to the optical pickup device 1, it is possible to appropriately adjust the angle θ only by adjusting (finely adjusting) the maximum radiation angle direction of the laser light within a range of ± 1.4 deg.

  The configuration of the present invention can be variously modified in addition to the above-described embodiments and modifications without departing from the spirit of the invention. That is, the above-described embodiment is an example in all respects, and should be considered not restrictive. The technical scope of the present invention is shown not by the above description of the embodiment but by the scope of the claims, and is understood to include all modifications within the meaning and scope equivalent to the scope of the claims. Should. Further, the present invention can be used for various optical disk devices.

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 11 Laser diode 12 Beam splitter 13 Collimate lens 14 Mirror 15 Front monitor IC
16 Lens actuator 17 Cylindrical lens 18 PDIC
18a to 18e Light receiving sensor 19a FE detection unit 19b TE detection unit 20a Focus control unit 20b Tracking control unit 3 Reproduction signal processing circuit 5 Optical disc reproduction device (optical disc device)
9 Optical disc GR grating element (diffraction grating)

Claims (9)

A focused spot forming unit that irradiates an information recording surface of an optical disc with a laser beam to form a focused spot;
A diffraction grating that divides the reflected light reflected from the focused spot into main diffracted light and sub-diffracted light;
A 0th light receiving part for receiving the main diffracted light;
A first light receiving unit that receives first region light including the PP component of the sub-diffraction light;
A second light receiving unit that receives second region light including a DC component of the sub-diffraction light;
A TE signal generating unit that generates a tracking error signal based on at least the intensity of light received by the second light receiving unit,
The first light receiving part and the second light receiving part are arranged at positions away from the 0th light receiving part,
The condensing spot forming part is
An optical pickup device formed so that a condensing spot direction in which a diameter of the condensing spot is maximum is shifted from a radial direction of the optical disc. The condensing spot forming part is
Forming the focused spot on the information recording surface of a predetermined target layer in the optical disc having a multilayer structure,
The first light receiving part and the second light receiving part are
2. The optical pickup device according to claim 1, wherein the intensity of the other-layer stray light reflected from a layer other than the target layer is arranged at a position where the intensity is weaker than the position of the 0th light receiving unit. The second light receiving unit is
The optical pickup device according to claim 2, wherein the other-layer stray light is arranged at a position where the intensity of the stray light in the other layer is weaker than the position of the first light receiving unit. The diffraction grating is
The reflected light is divided into the main diffracted light and the sub diffracted light and is emitted,
4. The optical pickup device according to claim 3, wherein the sub-diffracted light is formed so as to be emitted in a form divided into first region light and second region light. The main diffracted light is zero-order diffracted light by the diffraction grating,
The optical pickup device according to claim 4, wherein the sub-diffracted light is ± first-order diffracted light by the diffraction grating.   6. The optical pickup device according to claim 1, wherein an angle between the focused spot direction and the track direction of the optical disc is within a range of 55 ± 5 deg.   7. The optical pickup device according to claim 6, wherein the angle is adjusted so that the angle falls within a range of 55 ± 5 deg by adjusting the maximum radiation angle direction of the laser beam.   8. The light according to claim 7, wherein the angle adjustment is performed by adjusting the maximum radiation angle direction within a range of ± 1.4 deg in a rotation direction centering on an emission direction of the laser light. Pickup device. An optical pickup device according to any one of claims 1 to 8,
An optical disc apparatus for reading data from or recording data on the optical disc.

Images