JP2005346849A - Optical pickup and phase modulation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup and phase modulation apparatus in which influence by a defective converged spot caused by existence of a power feeding wire of a liquid crystal element for phase modulation can be suppressed to the minimum. <P>SOLUTION: In the optical pickup provided with a light source emitting light for a rotated optical recording medium, a photodetector detecting reflected light of light emitted to the optical recording medium from the light source, and a first liquid crystal element for phase modulation having a first electrode 58 and first power feeding wires 51, 52 connected electrically to the first electrode 58, the first power feeding wires 51, 52 are arranged so that regions corresponding to the first power feeding wires 51, 52 are positioned in the optical spot irradiated to the optical recording medium and they are positioned at a direction between a rotation direction (tangential direction) 80 and a radial direction (radial direction) 81 of the optical recording direction in the light spot. Thereby, reduction of resolution in the rotation direction and the radial direction of the light spot can be suppressed as much as possible, influence by the defective light spot caused by existence of the first power feeding wires 51, 52 can be suppressed to the minimum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup used in various optical recording and / or reproducing apparatuses such as an optical disk system, a magneto-optical disk system, and an optical card system.

  In recent years, in various recording / reproducing apparatuses using an optical disc, in order to increase the recording capacity of the optical disc, a short wavelength semiconductor laser (LD) is used as a light source of an optical pickup, and an open efficiency NA is used as an objective lens. High lens is used. As described above, when the wavelength of the LD is shortened and the NA of the objective lens is increased, there arises a problem that aberrations easily increase due to various manufacturing errors and the optical function is deteriorated. Therefore, as a method for correcting this aberration, there is a method using a liquid crystal element. In this method, a liquid crystal element is inserted between the laser and the objective lens to give a desired phase distribution to the transmitted light. That is, using a liquid crystal element, an aberration-free state is obtained on the imaging surface by giving in advance a phase opposite to the aberration to the incident light of the objective lens.

The liquid crystal element described above is configured by sandwiching liquid crystal between a pair of substrates. An electrode is formed on each of the pair of substrates, and a plurality of electrodes divided concentrically are formed on one substrate. A voltage according to a desired phase distribution is separately applied to a plurality of electrodes divided concentrically to give a desired phase distribution to transmitted light that passes through the liquid crystal element (for example, Patent Document 1). reference.). A power supply wiring for supplying a voltage to each electrode is provided on a substrate on which a plurality of concentrically divided electrodes are formed. The power supply wiring is arranged so as to be positioned corresponding to the condensing spot irradiated on the optical disk.
JP 2002-251774 A (paragraphs [0015] to [0021], FIGS. 1 and 2)

  However, in the liquid crystal element as described above, the power supply wiring is provided so as to be positioned corresponding to the condensing spot irradiated on the optical disk. Therefore, in the region where the power supply wiring is provided, the phase modulation is performed. Therefore, it is impossible to apply a voltage effective to the liquid crystal and to provide a desired phase. For this reason, there is a problem that the shape of the condensed spot that passes through the liquid crystal element and is condensed on the optical disk becomes defective, and the tracking servo characteristic is deteriorated and the frequency characteristic of the reproduction signal is deteriorated.

  In view of the circumstances as described above, it is an object of the present invention to provide an optical pickup and a phase modulation device that can minimize the influence of a condensing spot defect caused by the presence of a power supply wiring of a liquid crystal element for phase modulation. There is.

  In order to achieve the above object, an optical pickup of the present invention includes a light source that emits light to a rotating optical recording medium, and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. And a first liquid crystal element for phase modulation, provided in a first optical path from the light source to the optical recording medium, having a first electrode and a first power supply wiring electrically connected to the first electrode. In the optical pickup provided, in the optical spot irradiated to the optical recording medium, a region corresponding to the first power supply wiring is located in the optical spot and is between the rotation direction and the radial direction of the optical recording medium. The first power supply wiring is arranged so as to be located in the azimuth direction.

  In the optical pickup of the present invention, by providing the first liquid crystal element for phase modulation, the aberration of the optical system generated in the first optical path can be corrected by the phase distribution given by the first liquid crystal element. Further, in the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the direction between the rotation direction and the radial direction of the optical recording medium, so that the first power supply wiring exists. By doing so, it is possible to specify the direction of occurrence of the defect of the light spot, and it is possible to minimize the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic. In the design of the liquid crystal element, the first power supply wiring is located in a region where aberration correction is to be performed, and a desired voltage cannot be applied to the region where the first power supply wiring is located, so that it corresponds to the first power supply wiring of the light spot. A defect occurs in the region, and a desired phase cannot be formed. For this reason, in the region corresponding to the first power supply wiring of the light spot emitted from the light source, transmitted through the first liquid crystal element, and irradiated on the optical recording medium, defects such as phase disturbance, intensity nonuniformity, and covering are present. It will be. For example, when the region corresponding to the first power supply wiring is arranged along the rotation direction of the optical recording medium, the light spot has a defect along the rotation direction. In this case, the pit pattern cannot be read accurately, an accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, when the region corresponding to the first power supply wiring is arranged along the radial direction of the optical recording medium, the light spot has a defect along the radial direction. In this case, the signal of the adjacent track is also detected, or an accurate tracking servo signal cannot be detected, and the tracking servo characteristics are deteriorated. On the other hand, in the optical pickup of the present invention, since the defect of the light spot occurs along the direction between the rotation direction and the radial direction, the decrease in resolution in the rotation direction and the radial direction of the light spot is suppressed as much as possible. be able to. Accordingly, it is possible to minimize the influence due to the light spot defect due to the presence of the power supply wiring, for example, the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic.

  According to one aspect of the present invention, the phase modulation device includes a second electrode provided in a second optical path from the optical recording medium to the photodetector, and a second power supply wiring electrically connected to the second electrode. The second liquid crystal element is further provided.

  By providing the second liquid crystal element for phase modulation in this way, the aberration of the optical system that occurs in the second optical path can also be corrected by the phase distribution given by the second liquid crystal element. Therefore, it is possible to detect the focus servo signal, tracking servo signal, and reproduction signal satisfactorily.

  According to an aspect of the present invention, the second liquid crystal element is provided in the first optical path, and the first liquid crystal element and the second power supply line overlap with each other in a planar manner. A second liquid crystal element is disposed.

  As described above, when the first optical path and the second optical path are partially overlapped and the second liquid crystal element is provided on the second optical path and on the first optical path, the first power supply wiring and the second power supply wiring are planar. By arranging so as to overlap each other, a good light spot can be obtained. That is, when the second liquid crystal element is provided in the first optical path, the phase of the light transmitted through the first liquid crystal element and the second liquid crystal element is originally corrected in the first optical path by the first liquid crystal element, It is desirable that the second liquid crystal element is not affected. However, in reality, since the electrodes provided in the liquid crystal element are not completely transparent, for example, the first liquid crystal element and the first liquid crystal element are positioned so that the second power supply wiring region is located corresponding to the region where the first electrode is provided. When the second liquid crystal element is arranged, the light transmitted through the first liquid crystal element and the second liquid crystal element has a portion where the second power supply wiring region is located and a portion where the light is not located in the region where the first electrode is provided. However, the amount of light is slightly different, and there is a problem that the amount of light in the light spot irradiated on the optical recording medium becomes uneven in the plane. Therefore, by making the first power supply wiring of the first liquid crystal element and the second power supply wiring of the second liquid crystal element substantially planarly overlap, the light transmitted through the first liquid crystal element and the second liquid crystal element is In the region where the desired phase distribution of one liquid crystal element is formed, the optical recording medium can be irradiated with a good light spot because it is not affected by the presence of the second feeder wiring region. The same applies to the second optical path because the first liquid crystal element and the second liquid crystal element exist. That is, the light reflected from the optical recording medium and transmitted through the first liquid crystal element and the second liquid crystal element is affected by the presence of the first power supply wiring region in the region where the desired phase distribution of the second liquid crystal element is formed. Since it does not receive, a favorable light spot can be irradiated with respect to a photodetector.

  According to one aspect of the present invention, the light source emits light from the light source, passes through the first liquid crystal element, reflects the optical recording medium, and corresponds to the first power supply wiring in the light spot irradiated to the photodetector. And a region corresponding to the second power supply line in a light spot emitted from the light source, reflected from the optical recording medium, passed through the second liquid crystal element, and irradiated to the photodetector. Match.

  According to such a configuration, in the light spot irradiated to the photodetector, the defective part due to the first power supply wiring and the defective part due to the second power supply wiring can be arranged at the same position, and there are few defective parts. A light spot can be obtained.

  According to one aspect of the present invention, the objective lens for condensing the light emitted from the light source onto the information recording surface of the optical recording medium, and the 1 / disposed between the light source and the objective lens. An optical branching element that is disposed between a four-wavelength plate, the light source, and a quarter-wave plate, guides light from the light source to the optical recording medium side, and guides reflected light from the optical recording medium to the photodetector. The first liquid crystal element is disposed between the light source and a quarter-wave plate, and the second liquid crystal element is disposed between the quarter-wave plate and a photodetector, and the photodetector. The region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring region coincide with each other in the light spot irradiated on the light source.

  According to such a configuration, in the light spot irradiated to the photodetector, the defective portion due to the first power supply wiring and the defective portion due to the second power supply wiring can be arranged at the same position, and the light spot with few defective portions. Can be obtained.

  According to an aspect of the present invention, the photodetector is divided into a plurality of light receiving regions, and a region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring in a light spot irradiated on the photodetector. However, the first power supply wiring and the second power supply wiring are arranged so as to be located in a light spot irradiated on the photodetector and to be located in a predetermined light receiving area among the plurality of light receiving areas.

  In this way, the first power supply line and the region corresponding to the first power supply line and the area corresponding to the second power supply line are always located in a certain light receiving region in the light spot irradiated to the photodetector. Since the second power supply wiring is provided, it is possible to obtain an optical pickup having stable operation characteristics without causing an error in the servo signal calculation. In other words, the light spot irradiated on the photodetector has a defect in the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring. For example, if the position is displaced and the defective portion moves between two different light receiving areas in the photodetector, the servo signal calculation is incorrect, and an optical pickup having stable operating characteristics cannot be obtained. On the other hand, a defect occurs by providing the first power supply wiring and the second power supply wiring so that the defective portion caused by the first power supply wiring and the second power supply wiring is respectively located in a specific light receiving region in advance. In this light receiving region, adjustment can be made in advance so that signal detection can be performed by taking this defect into account, and an optical pickup having stable operation characteristics can be obtained without distorting the servo signal calculation.

  According to an aspect of the present invention, the photodetector has a plurality of light receiving regions divided along a rotational direction and a radial direction of the optical recording medium, and the second light spot irradiated to the photodetector is the second spot. The second power supply wiring is arranged so that a region corresponding to the power supply wiring is located in a light spot irradiated on the photodetector and in an orientation between the rotation direction and the radial direction of the optical recording medium. ing.

  According to such a configuration, in the light spot irradiated to the photodetector, the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring are located in the fixed light receiving regions, respectively. An optical pickup having stable operating characteristics can be obtained without moving across the light receiving area and without causing a miscalculation of servo signals. Note that the region corresponding to the first power supply wiring is provided so as to be positioned in the direction between the rotation direction and the radial direction of the optical recording medium in the light spot irradiated to the optical recording medium. The irradiated light spot is also located in the direction between the rotation direction and the radial direction of the optical recording medium. Here, as a comparative example, for example, a description will be given of a case where an area corresponding to the second power supply wiring is positioned along the rotation direction of the optical recording medium in the light spot irradiated on the photodetector. In this case, if a region corresponding to the second power supply wiring is located in the dead zone that is a boundary between a plurality of light receiving regions, a defective portion due to the presence of the second power supply wiring does not exist in the light receiving region. Will not be detected and will not cause any problems. However, in reality, the region corresponding to the second power supply wiring is shifted from the dead zone region due to variations in the arrangement position of the optical system, variations in the arrangement position of the light receiving regions divided by the photodetector, environmental changes such as temperature, and the like. There are things to do. At this time, if the region corresponding to the first power supply wiring region moves between two different light receiving regions in the light spot irradiated on the photodetector, the servo signal calculation is out of order, and the optical pickup having stable operating characteristics. You will not be able to get. The same applies to the case where the second power supply wiring is arranged along the radial direction, and the same applies to the first power supply wiring. On the other hand, the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring are located in the direction between the rotation direction and the radial direction of the optical recording medium in the light spot irradiated to the photodetector. As described above, by providing the first power supply wiring and the second power supply wiring, positional deviation occurs due to variations in the arrangement position of the optical system, variations in the arrangement position of the divided light receiving regions of the photodetector, environmental changes such as temperature, and the like. However, the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring are always located in the same light receiving region. Therefore, since it is possible to specify in advance in which light receiving area a defect caused by the first power supply wiring and the second power supply wiring occurs, in this light receiving area, it is possible to perform signal detection in consideration of this defect in advance. An optical pickup having stable operating characteristics can be obtained without any error in servo signal calculation.

  The phase modulation apparatus of the present invention is an optical pickup having a light source that emits light to a rotating optical recording medium and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. A phase modulation device provided in a first optical path from the light source to the optical recording medium, wherein the pair of substrates, a liquid crystal layer provided between the pair of substrates, and a first provided on the substrate 1 electrode and a first power supply wiring electrically connected to the first electrode, and a region corresponding to the first power supply wiring in the light spot irradiated to the optical recording medium is within the light spot. The first power supply wiring is disposed so as to be located in the direction between the rotation direction and the radial direction of the optical recording medium.

  By incorporating such a phase modulation device of the present invention into an optical pickup, the aberration of the optical system generated in the first optical path can be corrected by the phase distribution given by the phase modulation device. In addition, in the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the direction between the rotation direction and the radial direction of the optical recording medium. The occurrence direction of the light spot defect due to the presence can be specified, and the occurrence of the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic can be minimized. Because of the design of the phase modulation device, the first power supply wiring is located within the region to be corrected for aberrations, and a desired voltage cannot be applied to the region where the first power supply wiring is located. In such a region, a defect occurs, and a desired phase cannot be formed. Therefore, in the region corresponding to the first power supply wiring of the light spot that is emitted from the light source, passes through the phase modulation device, and is irradiated onto the optical recording medium, defects such as phase disturbance, non-uniformity of intensity, and hooking exist. become. For example, when the region corresponding to the first power supply wiring is arranged along the rotation direction of the optical recording medium, the light spot has a defect along the rotation direction. In this case, the pit pattern cannot be read accurately, an accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, when the region corresponding to the first power supply wiring is arranged along the radial direction of the optical recording medium, the light spot has a defect along the radial direction. In this case, the signal of the adjacent track is also detected, or an accurate tracking servo signal cannot be detected, and the tracking servo characteristics are deteriorated. On the other hand, in the optical pickup using the phase modulation apparatus of the present invention, the defect of the light spot occurs along the direction between the rotation direction and the radial direction. A reduction in resolution can be suppressed as much as possible, and an influence caused by a light spot defect due to the presence of the power supply wiring, for example, a deterioration in frequency characteristics of a reproduction signal and a deterioration in tracking servo characteristics can be suppressed to a minimum.

  Another phase modulation apparatus of the present invention includes a light source that emits light to a rotating optical recording medium, and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. Phase modulation comprising: a first liquid crystal element provided in a first optical path from the light source to the optical recording medium; and a second liquid crystal element provided in a second optical path from the optical recording medium to the photodetector. The first liquid crystal element includes a first electrode and a first power supply wiring electrically connected to the first electrode, and the second liquid crystal element includes a second electrode and the first electrode. A second power supply line electrically connected to the two electrodes, and in the light spot irradiated to the optical recording medium, a region corresponding to the first power supply line is irradiated to the optical recording medium Rotation of the optical recording medium located in A region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring in a light spot which is located in a direction between the direction and the radial direction and is applied to the photodetector, respectively, of the optical recording medium The first power supply wiring and the second power supply wiring are arranged so as to be positioned in an orientation between the rotation direction and the radial direction.

  By incorporating such a phase modulation device of the present invention into an optical pickup, the aberration of the optical system generated in the first optical path can be corrected by the phase distribution given by the first liquid crystal element, and the optical generated in the second optical path. The system aberration can be corrected by the phase distribution given by the second liquid crystal element. In addition, in the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the direction between the rotation direction and the radial direction of the optical recording medium. The occurrence direction of the light spot defect due to the presence can be specified, and the occurrence of the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic can be minimized. Because of the design of the phase modulation device, the first power supply wiring is located within the region to be corrected for aberrations, and a desired voltage cannot be applied to the region where the first power supply wiring is located. In such a region, a defect occurs, and a desired phase cannot be formed. Therefore, in the region corresponding to the first power supply wiring of the light spot that is emitted from the light source, passes through the phase modulation device, and is irradiated onto the optical recording medium, defects such as phase disturbance, non-uniformity of intensity, and hooking exist. become. For example, when the region corresponding to the first power supply wiring is arranged along the rotation direction of the optical recording medium, the light spot has a defect along the rotation direction. In this case, the pit pattern cannot be read accurately, an accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, when the region corresponding to the first power supply wiring is arranged along the radial direction of the optical recording medium, the light spot has a defect along the radial direction. In this case, the signal of the adjacent track is also detected, or an accurate tracking servo signal cannot be detected, and the tracking servo characteristics are deteriorated. On the other hand, in the optical pickup incorporating the phase modulation apparatus of the present invention, the defect of the light spot occurs along the direction between the rotation direction and the radial direction. Can be minimized, and the influence of the light spot defect due to the presence of the power supply wiring, for example, the degradation of the frequency characteristic of the reproduction signal and the degradation of the tracking servo characteristic can be minimized. In addition, since each of the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring is located in a specific light receiving region in the light spot irradiated to the photodetector, the calculation of the servo signal does not go wrong. An optical pickup having stable operating characteristics can be obtained. That is, the light spot irradiated on the photodetector has a defect in a region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring. For example, if the defective portion moves between two different light receiving areas in a light spot irradiated to the photo-detector due to positional deviation, the servo signal calculation is out of order, and an optical pickup having stable operating characteristics is obtained. It becomes impossible to do. On the other hand, since the light receiving area of the photodetector is usually divided substantially along the rotational direction and the radial direction of the optical recording medium, in the light spot irradiated to the photodetector, the area corresponding to the first power supply line and the second By arranging the first power supply line and the second power supply line so that the region corresponding to the power supply line is located in the direction between the rotation direction and the radial direction of the optical recording medium, the first power supply line and the second power supply line are arranged. Each defective portion caused by the power supply wiring is located in a specific light receiving region. As a result, the light receiving area where the defect occurs can be specified in advance, and the light receiving area where the defect occurs can be adjusted in advance so that the signal can be detected by taking into account the amount of the defect. Therefore, an optical pickup having stable operating characteristics can be obtained.

  Still another phase modulation apparatus according to the present invention includes a light source that emits light to a rotating optical recording medium, and a plurality of light receiving regions that detect reflected light of the light emitted from the light source to the optical recording medium. A first liquid crystal element provided in a first optical path from the light source to the optical recording medium, and a second optical path provided in a second optical path from the optical recording medium to the photodetector. And a first power supply wiring electrically connected to the first electrode, wherein the second liquid crystal element includes: a first liquid crystal element; Has a second electrode and a second power supply wiring electrically connected to the second electrode, and a region corresponding to the first power supply wiring in the light spot irradiated to the optical recording medium is Inside the light spot irradiated on the optical recording medium The first power supply wiring is provided so as to be positioned in an orientation between the rotation direction and the radial direction of the optical recording medium, and corresponds to the first power supply wiring in the light spot irradiated to the photodetector. The first power supply wiring and the second power supply wiring are arranged so that a region corresponding to the second power supply wiring and a region corresponding to the second power supply wiring are respectively positioned in a predetermined light receiving region among the plurality of light receiving regions.

  By incorporating such a phase modulation device of the present invention into an optical pickup, the aberration of the optical system generated in the first optical path can be corrected by the phase distribution given by the first liquid crystal element, and the optical generated in the second optical path. The system aberration can be corrected by the phase distribution given by the second liquid crystal element. In addition, in the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the direction between the rotation direction and the radial direction of the optical recording medium. It is possible to specify the direction of occurrence of a defect in the light spot due to the presence of noise, and to suppress the occurrence of deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic. Because of the design of the phase modulation device, the first power supply wiring is located within the region to be corrected for aberrations, and a desired voltage cannot be applied to the region where the first power supply wiring is located. In such a region, a defect occurs, and a desired phase cannot be formed. Therefore, in the region corresponding to the first power supply wiring of the light spot that is emitted from the light source, passes through the phase modulation device, and is irradiated onto the optical recording medium, defects such as phase disturbance, non-uniformity of intensity, and hooking exist. become. For example, when the region corresponding to the first power supply wiring is arranged along the rotation direction of the optical recording medium, the light spot has a defect along the rotation direction. In this case, the pit pattern cannot be read accurately, an accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, when the region corresponding to the first power supply wiring is arranged along the radial direction of the optical recording medium, the light spot has a defect along the radial direction. In this case, the signal of the adjacent track is also detected, or an accurate tracking servo signal cannot be detected, and the tracking servo characteristics are deteriorated. On the other hand, in the pickup incorporating the phase modulation device of the present invention, the defect of the light spot occurs along the direction between the rotation direction and the radial direction. A reduction in resolution can be suppressed as much as possible, and an influence caused by a light spot defect due to the presence of the power supply wiring, for example, a deterioration in frequency characteristics of a reproduction signal and a deterioration in tracking servo characteristics can be suppressed to a minimum. In addition, the first power supply wiring and the second power supply wiring are arranged so that the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring are located in a specific light receiving region in the light spot irradiated to the photodetector. Since the wiring is provided, it is possible to obtain an optical pickup having stable operation characteristics without causing an error in the servo signal calculation. That is, the light spot irradiated on the photodetector has a defect in a region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring. For example, if the defective portion moves between two different light receiving areas in a light spot that is misaligned and irradiates the photodetector, the servo signal calculation is incorrect, and an optical pickup with stable operating characteristics can be obtained. It becomes impossible. On the other hand, a defect occurs by providing the first power supply wiring and the second power supply wiring so that the defect occurrence portion caused by the first power supply wiring and the second power supply wiring is located in a specific light receiving region, respectively. In the light receiving region, it is possible to make adjustments so that signal detection can be performed in advance by taking into account the defective portion, and an optical pickup having stable operating characteristics can be obtained without causing an error in the servo signal calculation.

  Still another phase modulation apparatus of the present invention includes a light source that emits light to a rotating optical recording medium, and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. A phase modulation device provided in an optical path of the optical pickup from the light source to the optical recording medium and in an optical path from the optical recording medium to the photodetector, which is sequentially arranged with a predetermined gap. The first substrate, the second substrate and the third substrate, the first liquid crystal layer sandwiched between the first substrate and the second substrate, and the sandwiched between the second substrate and the third substrate. A second liquid crystal layer, a first electrode disposed on a surface of the first substrate or the second substrate on the first liquid crystal layer side, and a first power supply wiring electrically connected to the first electrode; The second liquid crystal of the second substrate or the third substrate A second electrode disposed on the side surface and a second power supply wiring electrically connected to the second electrode, and corresponds to the first power supply wiring in an optical spot irradiated to the optical recording medium The first power supply wiring is disposed so that the region is located in a light spot irradiated on the optical recording medium and located in an orientation between a rotation direction and a radial direction of the optical recording medium, The one power supply wiring and the second power supply wiring overlap in a planar manner.

  By incorporating such a phase modulation device of the present invention into an optical pickup, the aberration of the optical system generated in the first optical path is given by the liquid crystal element constituted by the first substrate, the second substrate and the first liquid crystal layer. The aberration can be corrected by the phase distribution, and the aberration of the optical system generated in the second optical path can be corrected by the phase distribution given by the liquid crystal element constituted by the second substrate, the third substrate, and the second liquid crystal layer. . In addition, in the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the direction between the rotation direction and the radial direction of the optical recording medium. It is possible to specify the direction of occurrence of a defect in the light spot due to the presence of noise, and to suppress the occurrence of deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic. Because of the design of the phase modulation device, the first power supply wiring is located within the region to be corrected for aberrations, and a desired voltage cannot be applied to the region where the first power supply wiring is located. In such a region, a defect occurs, and a desired phase cannot be formed. Therefore, in the region corresponding to the first power supply wiring of the light spot that is emitted from the light source, passes through the phase modulation device, and is irradiated onto the optical recording medium, defects such as phase disturbance, non-uniformity of intensity, and hooking exist. become. For example, when the region corresponding to the first power supply wiring is arranged along the rotation direction of the optical recording medium, the light spot has a defect along the rotation direction. In this case, the pit pattern cannot be read accurately, an accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, when the region corresponding to the first power supply wiring is arranged along the radial direction of the optical recording medium, the light spot has a defect along the radial direction. In this case, the signal of the adjacent track is also detected, or an accurate tracking servo signal cannot be detected, and the tracking servo characteristics are deteriorated. On the other hand, in the pickup incorporating the phase modulation device of the present invention, the defect of the light spot occurs along the direction between the rotation direction and the radial direction. A reduction in resolution can be suppressed as much as possible, and an influence caused by a light spot defect due to the presence of the power supply wiring, for example, a deterioration in frequency characteristics of a reproduction signal and a deterioration in tracking servo characteristics can be suppressed to a minimum. Moreover, a favorable light spot can be obtained by arranging the first power supply wiring and the second power supply wiring so as to overlap in a plane. That is, when the second liquid crystal element for correcting the aberration of the second optical path is provided in the first optical path, the light that originally passes through the first liquid crystal element and the second liquid crystal element in the first optical path is It is desirable that the phase is corrected by the liquid crystal element and not influenced by the second liquid crystal element. However, in reality, since the electrodes provided in the liquid crystal element are not completely transparent, for example, if the second power supply wiring region is disposed corresponding to the region where the first electrode is provided, the first liquid crystal element and the first liquid crystal element 2 The light transmitted through the liquid crystal element is slightly different in the portion where the second feeder wiring region is located and the portion where the second feeder wiring region is located in the region where the first electrode is provided. There is a problem that the amount of light in the irradiated light spot becomes uneven in the surface. Therefore, by making the first power supply wiring region of the first liquid crystal element and the second power supply wiring region of the second liquid crystal element overlap in a plane, the light transmitted through the first liquid crystal element and the second liquid crystal element is Since the region where the desired phase distribution of the first liquid crystal element is formed is not affected by the presence of the second power supply wiring region, a good light spot can be irradiated onto the optical recording medium. Further, since the first liquid crystal element and the second liquid crystal element are also present in the second optical path, the same can be said. The light reflected from the optical recording medium and transmitted through the first liquid crystal element and the second liquid crystal element is the second light path. In the region where the desired phase distribution of the liquid crystal element is formed, it is not affected by the presence of the first power supply wiring region, so that a good light spot can be irradiated to the photodetector.

  As described above, according to the present invention, it is possible to minimize the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First embodiment)

  FIG. 1 is a schematic configuration diagram showing the configuration of the optical system of the optical pickup according to the first embodiment of the present invention. An optical disk 8 as an optical recording medium is a phase change type disk or a metal film ROM disk. The signal recording surface is irradiated with laser light through the cover glass 7, and the pit pattern recorded on the signal recording surface is light. Read by the pickup 10. The optical pickup 10 has a biaxial actuator 9 on which the objective lens 6 is mounted, and the objective lens 6 is moved in the focus direction and the tracking direction by driving control of the biaxial actuator 9 to access the optical disc 8.

  In the first optical path between the laser light source (LD) 1 as the light source and the optical disk 8, in other words, in the laser light emission side optical path, the collimator lens 2, the polarization beam splitter 3 as the optical branching element, the phase modulation device 30, and A quarter-wave plate 5 and an objective lens 6 are provided as phase control elements.

  Further, in the second optical path between the optical disk 8 and the photodetector 70, in other words, on the light reflection side optical path, through which the reflected light irradiated by the optical disk 8 passes, the objective lens 6, the quarter wavelength plate 5, the phase modulation device. 30, a polarizing beam splitter 3, a focusing lens 11, and a multi-lens 12 are provided.

  The phase modulation device 30 includes a first liquid crystal element 30A and a second liquid crystal element 30B, and the aberration of light generated in the first optical path is changed to the aberration of light generated in the second optical path by the first liquid crystal element 30A. Is corrected by the second liquid crystal element 30B. Since the aberration generated in the first optical path and the aberration generated in the second optical path are equal to each other, the correction amount for correcting the aberration of the first liquid crystal element 30A and the second liquid crystal element 30B may be the same. In the present embodiment, the first optical path and the second optical path are partially shared, and the second liquid crystal element 30B is provided on the second optical path and also provided on the first optical path. It is in the state. Further, the position of the phase modulation device 30 in the xy direction is fixed with respect to the objective lens 6. In the optical path, the first liquid crystal element 30A is disposed between the laser light source 1 and the quarter wavelength plate 5, and the second liquid crystal element 30B is disposed between the quarter wavelength plate 5 and the photodetector 70. .

  Next, the structure of the phase modulation device 30 will be described with reference to FIGS.

  FIG. 2 is a schematic perspective view of the phase modulation device incorporated in the optical pickup shown in FIG. FIG. 3 is an exploded schematic perspective view of the phase modulation device. 4 is a cross-sectional view of the phase modulator taken along line AA ′ in FIG. FIG. 5 is a plan view showing the shapes of the electrodes and seals formed on the substrate that constitutes a part of the phase modulation device, and corresponds to a view when the substrate is observed from the direction of arrow B in FIG. 6 is a plan view showing the shapes of electrodes and seals formed on a substrate constituting another part of the phase modulation device, and corresponds to a view of the substrate observed from the direction of arrow A in FIG. FIG. 7 is a plan view showing shapes of electrodes and seals formed on the other surface of the substrate shown in FIG. 6, and corresponds to a view of the substrate observed from the direction of arrow B in FIG. FIG. 8 is a plan view showing the shapes of electrodes and seals formed on a substrate constituting still another part of the phase modulation apparatus, and corresponds to a view of the substrate observed from the direction of arrow A in FIG. . FIG. 9 is a plan view for explaining the rotation direction (tangential direction) and the radial direction (radial direction) of the optical disc. FIG. 10 is a cross-sectional view showing the state of liquid crystal molecules when the phase modulator is turned on and off. FIG. 11 is a diagram (No. 1) for explaining the positional relationship between the four light receiving regions provided in the photodetector in the present embodiment and the first power supply wiring of the first liquid crystal element provided in the phase modulation device. is there. FIG. 12 is a diagram for explaining the positional relationship between the four light receiving regions provided in the photodetector in the present embodiment and the second power supply wiring region of the second liquid crystal element provided in the phase modulation device. FIG. 13 is a diagram for explaining the relationship between the pits provided on the optical disc and the lights 82 to 85 irradiated on the optical disc. FIG. 14 is a diagram for explaining the positional relationship between the four light receiving regions provided in the photodetector in the present embodiment and the first power supply wiring region of the first liquid crystal element provided in the phase modulation device (part 2). It is. FIG. 15 is a diagram for explaining the positional relationship between the four light receiving regions provided in the photodetector in the present embodiment and the first power supply wiring region of the first liquid crystal element provided in the phase modulation device (part 3). It is. FIG. 16 is a diagram for explaining the positional relationship between the four light receiving regions provided in the photodetector as a comparative example and the first power supply wiring region of the first liquid crystal element provided in the phase modulation device (part 1). It is. FIG. 17 is a diagram for explaining the positional relationship between the four light receiving regions provided in the photodetector as a comparative example and the first power supply wiring region of the first liquid crystal element provided in the phase modulator (part 2). It is. Note that the x, y, and z coordinate axes illustrated in FIGS. 2 to 8 are provided because the positional relationship illustrated in the respective drawings is not constant. Also, the rotation direction (tangential direction) and the radial direction (radial direction) illustrated in FIGS. 5 to 8 and FIGS. 11 to 17 are the rotation direction (tangential direction) and the radial direction (radial direction) with respect to the optical disk described in FIG. Direction).

  As illustrated in FIGS. 1 to 4, the phase modulation device 30 includes a first liquid crystal element 30 </ b> A and a second liquid crystal element 30 </ b> B. Note that in FIG. 2, three substrates constituting the phase modulation device 30 are overlaid for easy viewing.

  In the phase modulation device 30, the three first substrates 40, the second substrate 50, and the third substrate 60 are arranged with a predetermined gap therebetween. The phase modulation device 30 has a rectangular planar shape, and the optical pickup 10 so that two orthogonal sides of the rectangle are parallel to the rotation direction (tangential direction) and the radial direction (radial direction) of the optical disc 8. Incorporated into.

  The first liquid crystal element 30 </ b> A is provided in a substantially rectangular shape along a pair of opposing rectangular first and second substrates 40 and 50, and an outer periphery of the substrate to which the first substrate 40 and the second substrate 50 are bonded. And a first liquid crystal layer 31A held in a space surrounded by the pair of first and second substrates 40 and 50 and the seal 32A. The seal 32A has a shape in which a portion serving as a liquid crystal injection port 32a is opened, and liquid crystal is injected between the pair of substrates 40 and 50 through the liquid crystal injection port 32a. The liquid crystal injection port 32a is sealed with a sealing material 33 after the liquid crystal is injected.

  On the other hand, the second liquid crystal element 30B includes a pair of opposing rectangular second substrate 50 and third substrate 60, and substantially rectangular along the substantially outer periphery of the substrate to which the second substrate 50 and the third substrate 60 are bonded. A seal 32B containing conductive particles provided in a shape, and a second liquid crystal layer 31B held in a space surrounded by the pair of second substrate 50 and third substrate 60 and the seal 32B. The first liquid crystal element 30A and the second liquid crystal element 30B share the second substrate 50. The seal 32B has a shape in which a portion serving as a liquid crystal injection port 32b is opened, and liquid crystal is injected between the pair of substrates 50 and 60 through the liquid crystal injection port 32b. The liquid crystal injection port 32b is sealed with a sealing material 33 after the liquid crystal is injected.

  As shown in FIGS. 3 to 5, the first substrate 40 has a first surface 40 a and a second surface 40 b that face each other, and the second surface 40 b faces the first surface 50 a of the second substrate 50. . On the second surface 40b of the first substrate 40, a solid transparent counter electrode 41 and connection wirings 42 electrically connected to the counter electrode 41 are disposed, and the alignment film is further covered so as to cover these electrodes. 43 is arranged. The connection wiring 42 is provided so as to extend into the formation region of the seal 32A.

  As shown in FIG. 3, the second substrate 50 has a first surface 50a and a second surface 50b facing each other. The first surface 50a is on the first substrate 40 side, and the second surface 50b is on the third substrate 60 side. To position.

  As shown in FIGS. 3, 4, and 6, a plurality of transparent first electrodes 58 are provided substantially concentrically on the first surface 50 a of the second substrate 50. The first electrode 58 includes a first A electrode 58a, a first B electrode 58b, a first C electrode 58c, a first D electrode 58d, a first E electrode 58e, a first F electrode 58f, a first G electrode 58g, which are provided in this order from the center of the concentric circle. It consists of a first H electrode 58h. The first A electrode 58a has a circular shape, and the first B electrode 58b to the first H electrode 58h each have a circular shape with a frame that is partially cut off. Further, on the first surface 50a of the second substrate 50, the first A power supply wiring 51, the first A electrode 58a and the first H electrode 58h as the first power supply wiring electrically connected to the first E electrode 58e are electrically connected. A first C power supply terminal that is electrically connected to the first B power supply wiring 52 as the first power supply wiring to be connected, the connection wiring 42 provided on the first substrate 40, and the conductive particles contained in the seal 32A. 53 is provided. A high resistance wiring 59 electrically connected to the first electrodes 58 is provided between the adjacent first electrodes 58 among the plurality of first electrodes 58. In the region surrounded by the seal 32A, the first electrode 58, the high resistance wiring 59, the first A power supply wiring 51, and the first B power supply wiring 52 are covered with an alignment film 54.

  The second substrate 50 has a projecting portion 50 c that projects from the first substrate 40, and includes a first A power supply terminal 51 a that is one end portion of the first A power supply wiring 51 and a first B power supply terminal 52 a that is one end portion of the first B power supply wiring 52. The first C power supply terminal 53 is provided on the first surface 50a side of the protruding portion 50c.

  The light emitted from the laser light source 1 and transmitted through the phase modulation device 30 has a one-to-one relationship with the light spot condensed on the optical disk 8, and the first light is collected in the light collection spot as the light spot to be collected. The first A power supply wiring 51 and the first B power supply wiring 52 are arranged so that regions corresponding to the 1A power supply wiring 51 and the first B power supply wiring 52 are located. In the first power supply wiring region 57 where the first A power supply wiring 51 and the first B power supply wiring 52 are provided, the first electrode 58 for giving a desired potential distribution to the first liquid crystal 31A is not provided. The first A power supply wiring 51 and the first B power supply wiring 52 are provided at the discontinuous portions of the first B electrode 58b to the first H electrode 58h located on substantially the same line, and are provided substantially along the radial direction of the concentric first electrode 58. It has been. In the present embodiment, by providing the high resistance wiring 59, the number of power supply wirings used for applying a voltage to each first electrode 58 is reduced. For ease of understanding, a case where the first B power supply wiring 52 is connected only to the first A electrode 58a will be described as an example. When a voltage is applied to the first A electrode 58a via the first B power supply wiring 52, a voltage that causes a voltage drop due to the resistance of the high resistance wiring 59 is supplied to the first B electrode 58b to the first H electrode 58h, and each first electrode Different voltages are supplied to 58a to 58h. Accordingly, by providing the high resistance wiring 59 as in the present embodiment, it is possible to supply different values of voltage to a plurality of different electrodes with one power supply wiring. In the present embodiment, two first A power supply lines 51 and 1B power supply lines 52 are provided, and among the first electrodes 58 divided into eight, the first A electrode 58a and the first H electrode 58h located on the innermost side and the outer side, The first B power supply wiring 52 is electrically connected, and the first E electrode 58e and the first A power supply wiring 51 are electrically connected. Then, a voltage is supplied to each of the first A power supply wiring 51, the first B power supply wiring 52, and the counter electrode 41, thereby forming a phase distribution for canceling out aberrations in the first liquid crystal element 30A.

  In the light condensing spot condensed on the optical disk 8, the area corresponding to the first power supply wiring area 57 in which the first A power supply wiring 51 and the first B power supply wiring 52 are provided is the rotation direction (tangential direction) of the optical disk 8. 80 and the radial direction (radial direction) 81, in other words, the first feeder wiring region 57 is located not in the rotational direction (tangential direction) 80 but in an orientation other than the radial direction (radial direction) 81. Is arranged. In the present embodiment, the first A power supply wiring 51 and the first B power supply wiring 52 are provided so as to correspond to the direction of an angle of about 45 degrees from the rotation direction (tangential direction) 80. Further, the first A power supply wiring 51 and the first B power supply wiring 52 are not in a positional relationship parallel to the side of the rectangular second substrate 50 and are provided to be inclined with respect to the side. In addition, the region corresponding to the first power supply wiring region 57 is positioned corresponding to any one of a plurality of light receiving regions 71 divided into a plurality in the photodetector 70 as will be described later, in the light spot irradiated to the photodetector. It is provided as follows.

  As shown in FIGS. 3, 4, and 7, a plurality of transparent second electrodes 158 are provided substantially concentrically on the second surface 50 b of the second substrate 50. The second electrode 158 includes a second A electrode 158a, a second B electrode 158b, a second C electrode 158c, a second D electrode 158d, a second E electrode 158e, a second F electrode 158f, a second G electrode 158g, which are provided in this order from the center of the concentric circle. It consists of a second H electrode 158h. The second A electrode 158a has a circular shape, and the second B electrode 158b to the second H electrode 158h each have a circular shape with a frame that is partially cut off. Further, on the second surface 50b of the second substrate 50, a second A power supply wiring 151 electrically connected to the second E electrode 158e, a second B power supply wiring electrically connected to the second A electrode 158a and the second H electrode 158h. 152, a second C power supply terminal 153 that is electrically connected to the connection wiring 62 provided on the third substrate 60 described later and the conductive particles contained in the seal 32B is provided. Further, a high resistance wiring 159 electrically connected to the second electrodes 158 is provided between adjacent second electrodes 158 among the plurality of second electrodes 158. In the region surrounded by the seal 32B, the second electrode 158, the high resistance wiring 159, the second A power supply wiring 151, and the second B power supply wiring 152 are covered with the alignment film 55.

  The second substrate 50 has a protruding portion 50 c protruding from the third substrate 60. The second A power supply terminal 151 a that is one end of the second A power supply wiring 151 and the second B power supply terminal 152 a that is one end of the second B power supply wiring 152. The second C power supply terminal 153 is provided on the second surface 50b side of the projecting portion 50c.

  In the second power supply wiring region 157 where the second A power supply wiring 151 and the second B power supply wiring 152 are provided, the second electrode 158 for giving a desired potential distribution to the second liquid crystal 31B is not provided. The second power supply wirings 151 and 152 are provided at the discontinuous portions of the second B electrode 158b to the second H electrode 158h located substantially on the same line, and are provided substantially along the radial direction of the concentric electrode 158. Also in the second liquid crystal element 30B, similarly to the first liquid crystal element 30A, by providing the high resistance wiring 159, the number of power supply wirings used for applying a voltage to each second electrode 158 is reduced. Yes. Two second power supply lines 151 and 152 are provided, and the second A electrode 158a and the second H electrode 158h, which are the innermost and outermost of the eight divided second electrodes 158, and the second B power supply line 152 are electrically connected. The second E electrode 158e and the second A power supply wiring 151 are electrically connected. Then, by supplying a voltage to each of the second power supply wirings 151 and 152 and a counter electrode 61 described later, a phase distribution for offsetting optical aberration generated in the second optical path is formed in the second liquid crystal element 30B. Let Further, the second A power supply wiring 151 and the second B power supply wiring 152 are not in a positional relationship parallel to the side of the rectangular second substrate 50 and are provided to be inclined with respect to the side.

  A condensing spot transmitted through the second liquid crystal element 30B and condensed on the optical disc 8 corresponds to the second power feeding distribution region 157 in which the second A power feeding wiring 151 and the second B power feeding wiring 152 are provided. The region is located in the focused spot, and is not an orientation between the rotation direction (tangential direction) 80 and the radial direction (radial direction) 81 of the optical disk 8, in other words, the rotation direction (tangential direction) 80. And it is located in the direction which is not radial direction (radial direction) 81. In the present embodiment, the second power supply wiring region 157 is arranged so as to be positioned at an angle of approximately 45 degrees from the rotation direction (tangential direction) 80.

  In addition, in the light spot that is transmitted through the second liquid crystal element 30 </ b> B and applied to the photodetector, the region corresponding to the second power supply wiring region 157 is any of the light receiving regions 71 that are divided into a plurality of portions in the photodetector 70 as will be described later. The second power supply wiring region 157 is arranged so as to be located in one.

  In the present embodiment, when the phase modulation device 30 is viewed from the thickness direction, the electrodes and wirings formed on the first surface 50a of the substrate 50 and the electrodes and wirings formed on the second surface 50b are planar. Are formed so as to overlap each other. In other words, the first electrode 58 and the second electrode 158 are not formed, and the first power supply wiring region 57 and the second power supply region 57 and the second liquid crystal layer 31B that cannot give a desired phase to each of the first liquid crystal layer 31A and the second liquid crystal layer 31B. The power supply wiring region 157 overlaps with the plane.

  As shown in FIGS. 3, 4, and 8, the third substrate 60 has a first surface 60 a, and the first surface 60 a faces the second surface 50 b of the second substrate 50. On the first surface 60 a of the third substrate 60, a solid transparent counter electrode 61 and a connection wiring 62 that is electrically connected to the counter electrode 61 are arranged. Further, an alignment film 63 is disposed so as to cover these electrodes. The connection wiring 62 is provided so as to extend into the formation region of the seal 32B.

  The liquid crystal injection ports 32a and 32b are provided corresponding to the sides orthogonal to the sides corresponding to the protruding portions 50c of the second substrate 50 where the power supply terminals are arranged. The two liquid crystal injection ports 32 a and 32 b are sealed with a common sealing material 33.

The first electrode 58 and the second electrode 158, the counter electrodes 41 and 61, the connection wires 42 and 62, the first power supply wires 51 and 52, the second power supply wires 151 and 152, the first C power supply terminal 53, and the second C power supply. The terminals 153 are all transparent conductive films. For example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), AZO (Al ₂ O ₃ ), SnO ₂ —Sb ₂ O _3, or the like can be used as the transparent conductive film material. A polyimide film is used for the alignment films 43, 54, 55 and 63.

  The liquid crystal used for the first liquid crystal layer 31A and the second liquid crystal layer 31B is the same type of liquid crystal, and is an optically uniaxial nematic liquid crystal material having a homogeneous (non-twisted) molecular arrangement. The alignment film 43 and the alignment film 54 provided in the first liquid crystal element 30A are aligned in the same direction, and the alignment films 55 and 63 provided in the second liquid crystal element 30B are respectively in the same direction. The first liquid crystal molecules 35A and the second liquid crystal molecules 35B are aligned along the alignment processing direction. Then, by applying a voltage to the first electrode 58 and the second electrode 158 and the counter electrodes 41 and 141, the arrangement of the liquid crystal molecules 35A and 35B can be displaced. Along with the displacement of the liquid crystal molecules 31A and 31B, the refractive index changes with respect to the polarization component along the alignment direction of the alignment film, so that the phase of transmitted light transmitted through the liquid crystal element can be changed. On the other hand, for polarized light in a direction orthogonal to the alignment direction of the alignment film, no phase change occurs because the refractive index is constant regardless of the application of voltage. The alignment direction in the first liquid crystal element 30A and the alignment direction in the second liquid crystal element 30B are orthogonal to each other. Therefore, as shown in FIG. 10A, when no voltage is applied to the first liquid crystal element 30A and the second liquid crystal element 30B, that is, when the power is off, the first liquid crystal molecules 35A and the second liquid crystal molecules 35B are The alignment films 54 and 43 and the alignment films 55 and 63 are arranged along the alignment direction, respectively. And as shown in FIG.10 (b), when the voltage was applied to the 1st liquid crystal element 30A and the 2nd liquid crystal element 30B, ie, the state at the time of power-on, it follows the surface direction of each board | substrate 40, 50, and 60. The sleeping first liquid crystal molecules 35A and second liquid crystal molecules 35B rise and change the refractive index, so that a phase distribution can be given to the transmitted light.

  Next, the relationship between the photodetector 70 and the phase modulation device 30 will be described.

  As shown in FIGS. 11 and 12, the photodetector 70 is divided into a plurality of light receiving regions, here divided into four divisions 71A, 71B, 71C, 71D. The division directions are a rotation direction (tangential direction) 80 and a radius. Along the direction (radial direction). In addition, between the adjacent light receiving regions among the divided light receiving regions is a dead zone region 72 where light is not detected. Here, the light that is reflected by the optical disk 8, passes through the objective lens 6, the quarter-wave plate 5, the phase modulation device 30, the polarization beam splitter 3, the focusing lens 11, and the multilens 12, and is focused on the photodetector 70. The spot has a one-to-one relationship with the light transmitted through the phase modulation device 30. In the present embodiment, the region corresponding to each of the first power supply wiring region 57 and the second power supply wiring region 157 in the condensing spot irradiated to the photodetector has a rotation direction (tangential direction) 80 and a radial direction (radial direction). It is located in the direction between 81. In other words, the first power supply wiring area 57 and the second power supply wiring area 157 are inclined with respect to a line (detector line) dividing the plurality of light receiving areas. Thereby, although the details will be described later, the regions corresponding to the first power supply wiring region 57 and the second power supply wiring region 157 of the condensing spot irradiated on the photodetector 70 are any of the light receiving regions 71A to 71D. It is located in one and does not lie across two light receiving areas.

  In the present embodiment, as shown in FIG. 11, the region corresponding to the first power supply wiring region 57 of the first liquid crystal element 30 </ b> A is located in the light receiving region 71 </ b> D in the condensing spot irradiated to the photodetector 70. On the other hand, the region corresponding to the second power supply wiring region 157 of the second liquid crystal element 30B is also located in the light receiving region 71D as shown in FIG. As described above, the first power supply wiring region 57 of the first liquid crystal element 30A and the second power supply wiring region 157 of the second liquid crystal element 30B are positioned so as to correspond to the same light receiving region 71D, respectively, and are collected to be irradiated to the photodetector 70. In the light spot, the first power supply wiring region 57 and the second power supply wiring region 157 have a matching positional relationship. As a result, the light collection spot irradiated on the photodetector 70 is a collection spot with fewer defects compared to the case where the region corresponding to the first power supply wiring region 57 and the region corresponding to the second power supply wiring region 157 do not match. Can be a light spot.

  Next, the operation of the optical pickup 10 described above, including the operation of the phase modulation device 30, will be described with reference to FIGS.

  The laser light emitted from the laser light source 1 enters the polarization beam splitter 3 after being collimated by the collimator lens 2. The linearly polarized light that has passed through the polarizing beam splitter 3 enters the phase modulation device 30 that is turned on, and a desired phase distribution is given by the first liquid crystal element 30A. Here, the alignment treatment direction applied to the alignment films 43 and 54 of the first liquid crystal element 30A matches the polarization direction of the incident linearly polarized light, and the alignment applied to the alignment films 55 and 63 of the second liquid crystal element 30B. The processing direction is orthogonal to the incident linear change polarization direction. For this reason, the incident linearly polarized light has its refractive index changed by the first liquid crystal element 30A and is not affected by the second liquid crystal element 30B.

  Next, the light transmitted through the phase modulation device 30 and given a desired phase distribution becomes circularly polarized light by the quarter wavelength plate 5, and is condensed on the signal surface of the optical disk 8 by the objective lens 6.

  Here, the aberration of the outward optical system is corrected by the phase distribution given by the first liquid crystal element 30A. As described above, the first A power supply wiring 51 of the first liquid crystal element 30A is used. In addition, since the first electrode 58 is not provided in the first power supply wiring region 57 where the first B power supply wiring 52 is provided, a desired voltage is not applied to this region. Therefore, in the light passing through the first liquid crystal element 30A, there are defects such as phase disturbance, intensity non-uniformity, and covering in the portion corresponding to the first power supply wiring region 57. The condensed spot that is collected is partially defective. As shown in FIG. 12, the focused spot focused on the optical disc 8 is desirably a small spot shape as indicated by reference numeral 83. However, because of the design of the first liquid crystal element 30A, the first power supply wiring region 57 must be provided in the region where the spherical aberration correction is to be performed, and thus there is a region corresponding to the first power supply wiring region 57 in the condensing spot. In the portion corresponding to the first power supply wiring region 57, there is inevitably a defect. Therefore, in the present embodiment, in the condensing spot condensed on the optical disc 8, the orientation between the rotation direction (tangential direction) 80 and the radial direction (radial direction) 81 of the optical disc 8, in this embodiment The first power supply wiring region 57 is provided so that the region corresponding to the first power supply wiring region 57 is located in the direction of the angle of approximately 45 degrees. As a result, the defective direction of the focused spot on the optical disk 8 can be arranged along the direction between the rotation direction (tangential direction) 80 and the radial direction (radial direction) 81 of the optical disk 8, and the reproduction signal It is possible to minimize the deterioration of the frequency characteristics and the tracking servo characteristics. That is, for example, in the condensing spot condensed on the optical disc 8, the first liquid crystal element so that the region corresponding to the first power supply wiring region 57 is positioned along the rotation direction (tangential direction) 80 of the optical disc 8. When 30A is arranged, the condensing spot 84 has a defect in the rotation direction (tangential direction) 80 as shown in FIG. For this reason, the pit pattern cannot be read accurately, the accurate reproduction signal cannot be detected, and the frequency characteristic of the reproduction signal is deteriorated. On the other hand, the first liquid crystal element 30 </ b> A is arranged so that the portion corresponding to the first power supply wiring region 57 is positioned along the radial direction (radial direction) 81 of the optical disc 8 in the condensing spot condensed on the optical disc 8. When arranged, as shown in FIG. 12, the focused spot 85 has a defect in the radial direction (radial direction) 80. For this reason, the signal of the adjacent track is also detected, the accurate tracking servo signal cannot be detected, and the tracking servo characteristic is deteriorated. On the other hand, in this embodiment, since the defect of the condensing spot 86 can be specified to occur in a direction between the rotation direction (tangential direction) 80 and the radial direction (radial direction) 81, the condensing spot The reduction in resolution in the rotation direction (tangential direction) and radial direction (radial direction) can be suppressed as much as possible. Accordingly, it is possible to minimize the influence due to the condensing spot defect due to the presence of the power supply wiring, for example, the deterioration of the frequency characteristic of the reproduction signal and the deterioration of the tracking servo characteristic.

  In the present embodiment, in the phase modulation device 30, the first power supply wiring region 57 of the first liquid crystal element 30A and the second power supply wiring region 157 of the second liquid crystal element 30B overlap in a plane. Thereby, a good condensing spot can be obtained. That is, in the first optical path, it is desirable that the first liquid crystal element 30A is inherently active with respect to the transmitted light, and the second liquid crystal element 30B can be ignored. However, since the transparent electrode used for the liquid crystal element is not completely transparent, for example, if the second power supply wiring region 157 is located corresponding to the region where the first electrode 58 is provided, the first electrode In the region where the second power supply wiring region 157 is located and the portion where the second feeder wiring region 157 is located, the amount of light is slightly different in the region where the second power supply wiring region 157 is located, and the amount of light in the focused spot is uneven in the plane. There are problems such as becoming. Therefore, in the present embodiment, the first power supply wiring region 57 of the first liquid crystal element 30A and the second power supply wiring region 157 of the second liquid crystal element 30B are configured to overlap each other in a planar manner, so A portion corresponding to the phase modulation effective region (region in which a desired phase distribution is formed by the first electrode 58 and the high resistance wiring 59) of the one liquid crystal element 30A is affected by the presence of the second power supply wiring region 157. Therefore, a good condensing spot can be obtained. Although the first optical path has been described here, the same applies to the second optical path because the first liquid crystal element 30A and the second liquid crystal element 30B exist. That is, the phase modulation effective region (second electrode 158 and high resistance of the second liquid crystal element 30B) of a condensing spot formed by condensing light that is transmitted through the phase modulation device 30 and phase-modulated by the second liquid crystal element 30B. Since the portion corresponding to the region where the desired phase distribution is formed by the wiring 159 is not affected by the presence of the first power supply wiring region 57, a good condensing spot can be obtained. If the influence due to the presence of the power supply wiring region as described above is negligible, the first power supply wiring region 57 of the first liquid crystal element 30A and the second power supply wiring region 157 of the second liquid crystal element 30B are planar. The first power supply wiring 57 and the second power supply wiring 157 may be arranged so as to be different from each other by 180 degrees in plan view with the optical axis of the optical path as the center.

  Next, the light reflected by the optical disk 8 passes through the quarter wavelength plate 5 again and becomes linearly polarized light orthogonal to the forward path. This linearly polarized light is incident on the phase modulator 30 that is powered on. The linearly polarized light incident on the phase modulation device 30 is given a desired phase distribution by the second liquid crystal element 30B having the alignment films 55 and 63 that have been subjected to alignment processing along the polarization direction. On the other hand, since the alignment direction of the liquid crystal molecules 35A in the first liquid crystal element 30A is orthogonal to the polarization direction of the incident linearly polarized light, the refractive index of the incident linearly polarized light is changed by the second liquid crystal element 30B. The first liquid crystal element 30A is not affected. Thereby, the aberration of the light returned from the signal recording surface of the optical disk 8 is corrected.

  Here, the aberration of the optical system in the second optical path is corrected by the phase distribution given by the second liquid crystal element 30B. As described above, the second A power supply line 151 and the second power supply line 151 of the second liquid crystal element 30B are used. Since the second electrode 158 is not provided in the second power supply wiring region 157 where the 2B power supply wiring 152 is provided, a desired voltage is not applied to this region. Therefore, such light passing through the second liquid crystal element 30B has defects such as phase disturbance, non-uniform intensity, and covering in a region corresponding to the second power supply wiring region 157.

  Next, the light transmitted through the phase modulator 30 is reflected by the polarization beam splitter 3 and is incident on the photodetector 70, and a focus servo signal, tracking servo signal, and reproduction signal are detected from the output of the photodetector 70.

  As described above, the photodetector 70 is divided into a plurality of light receiving areas 71A, 71B, 71C, 71D. As shown in FIG. 11, the region corresponding to the first power supply wiring region 57 of the first liquid crystal element 30A in the condensing spot irradiated to the photodetector 70 is located in the light receiving region 71D. On the other hand, in the condensing spot irradiated to the photodetector 70, the region corresponding to the second power supply wiring region 157 of the second liquid crystal element 30B is also positioned corresponding to the light receiving region 71D as shown in FIG. Yes. As described above, the regions corresponding to the first power supply wiring region 57 of the first liquid crystal element 30A and the second power supply wiring region 157 of the second liquid crystal element 30B are located in the same light receiving region, respectively, and are collected to be irradiated to the photodetector 70. In the light spot, the first power supply wiring region 57 and the second power supply wiring 157 have a matching positional relationship.

  In the condensing spot irradiated to the photodetector 70, regions corresponding to the first power supply wiring region 57 and the second power supply wiring region 157 are a rotation direction (tangential direction) 80 and a radial direction (radial direction) 81 in the optical disc 8. It is located in the direction between. As a result, as shown in FIGS. 14 and 15, in the condensing spot irradiated to the photodetector 70, the variation in the arrangement position of the optical system, the variation in the arrangement position of the divided light receiving region 71 of the photodetector 70, the temperature, etc. Even if the region corresponding to the first power supply wiring region 57 is displaced due to environmental changes, the portion corresponding to the first power supply wiring region 57 is always located in the light receiving region 71D and moves across two different light receiving regions. There is nothing to do. Further, the same can be said for the second power supply wiring region 157. Even if a positional shift occurs, the portion corresponding to the second power supply wiring region 157 is always located in the light receiving region 71D and spans two different light receiving regions. There is no movement.

  Next, a comparative example for this will be described with reference to FIGS. For example, a region corresponding to the first power supply wiring region 57 ′ in which the first A power supply wiring 51 ′ and the first B power supply wiring 52 ′ are provided in the radial spot (radial direction) 80 in the light condensing spot irradiated to the photodetector 70. The case where it arrange | positions along is demonstrated. As shown in FIG. 16, if the first power supply wiring region 57 ′ is located in the dead zone 72, defective portions due to the presence of the first power supply wiring region 57 ′ do not exist in the light receiving regions 71 </ b> A to 71 </ b> D. Will not be detected and will not cause any problems. However, in practice, the first power supply wiring region 57 ′ is displaced from the dead zone region 72 due to variations in the arrangement position of the optical system, variations in the arrangement position of the divided light receiving regions 71 of the photodetector 70, and environmental changes such as temperature. May be located. Then, when the position is shifted and the portion corresponding to the first power supply wiring region 57 ′ moves between the two light receiving regions 71 </ b> B and 71 </ b> D, for example, as shown in FIGS. 17A and 17B. The calculation of the servo signal is out of order, making it impossible to obtain an optical pickup with stable operating characteristics. The same applies to the case where the first power supply wiring region 57 ′ is arranged along the rotation direction (tangential direction), and the portion corresponding to the first power supply wiring region 57 ′ moves between two light receiving regions that are different. If this happens, the calculation of the servo signal goes wrong, and an optical pickup with stable operating characteristics cannot be obtained.

  In the present embodiment, a plurality of light receiving regions 71 of the photodetector 70 are provided along the rotation direction (tangential direction) 80 and the radial direction (radial direction) 81 of the optical disc 8, and further, the first liquid crystal element 30A has the first liquid crystal element 30A. A region corresponding to the power supply wiring region 57 is provided so as to be located in a direction between a rotation direction (tangential direction) 80 and a radial direction (radial direction) 81 in the optical disc 8. Accordingly, as described with reference to FIGS. 14 and 15, even if a positional deviation occurs, a portion corresponding to the first power supply wiring region 57 is located in one light receiving region (here 71D), It does not move across two different light receiving areas. Therefore, since the light receiving area where the defect occurs can be specified in advance, the light receiving area of the photodetector 70 can be adjusted in advance so that signal detection can be performed by taking this defect into account, and the servo signal calculation can be performed. An optical pickup having stable operating characteristics can be obtained without going crazy. Here, the positional relationship between the light receiving region 71 of the photodetector 70 and the power supply wiring has been described by taking the first power supply wiring region 57 of the first liquid crystal element 30A as an example, but the second power supply of the second liquid crystal element 30B has been described. The same can be said for the wiring region 157.

  In the above description, in the phase modulation device 30, the concentric electrodes are provided on both surfaces of the second substrate 50, and the solid counter electrodes are provided on the first substrate 40 and the third substrate 60. However, the present invention is not limited to this. is not. A solid counter electrode may be provided on both surfaces of the second substrate 50, and concentric electrodes may be provided on the first substrate 40 and the third substrate 60, or concentric electrodes on the first substrate 40 and the second substrate 50. A counter electrode on the surface (first surface) of the first substrate 40, a concentric electrode on the surface (second surface) of the second substrate 50 on the third substrate 60, and a counter electrode on the third substrate 60. Alternatively, the first substrate 40 may be a counter electrode, the second substrate 50 may be a concentric electrode on the first substrate 40 side (first surface), and the second substrate 50 may be a third substrate 60 side (second surface). Surface) and a concentric electrode on the third substrate 60 may be provided.

  (Second Embodiment)

  Next, an optical pickup according to the second embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the structure similar to the optical pick-up concerning 1st Embodiment, and only a different structure is demonstrated.

  FIG. 18 is a schematic configuration diagram showing the configuration of the optical system of the optical pickup 110 according to the second embodiment of the present invention.

  In the phase modulation device 30 according to the first embodiment, the two liquid crystal elements 30A and 30B share a single substrate and have a shape in which the two liquid crystal elements are integrated. In the device 130, the first liquid crystal element 130A and the second liquid crystal element 130B are independent without sharing the substrate.

  Here, the aberration generated in the first optical path is corrected by the first liquid crystal element 130A, and the aberration generated in the second optical path is corrected by the second liquid crystal element 130B.

  The first liquid crystal element 130A includes a pair of substrates 140 and 150, and a first liquid crystal layer 31A sandwiched between the substrates. On the first liquid crystal layer 31 </ b> A side of the substrate 140, the counter electrode and the connection wiring having the same shape and arrangement as the counter electrode 41 and the connection wiring 42 provided on the second surface 40 b of the first substrate 40 in the first embodiment. Is provided. In addition, on the first liquid crystal 31A side of the substrate 150, concentric first electrodes 58, a first A power supply wiring 51, and a first B power supply wiring 52 provided on the first surface 50a of the second substrate 50 in the first embodiment. The first electrode having the same shape and arrangement as the first C connection terminal 53, the first A power supply wiring, the first B power supply wiring, and the first C connection terminal are provided. Further, an alignment film is provided on the first liquid crystal layer 31A side of each of the substrates 140 and 150 so as to cover the above-described electrodes.

  The second liquid crystal element 130B includes a pair of substrates 160 and 170 and a second liquid crystal layer 31B sandwiched between the substrates. On the second liquid crystal 31B side of the substrate 170, concentric second electrodes 158 provided on the second surface 50b of the second substrate 50 in the first embodiment, the second A power supply wiring 151, the second B power supply wiring 152, the first A second electrode, a second A power supply wiring, a second B power supply wiring, and a second C connection terminal having the same shape and arrangement as the 2C connection terminal 153 are provided. On the second liquid crystal 31B side of the substrate 160, the counter electrode and the connection wiring having the same shape and arrangement as the counter electrode 61 and the connection wiring 62 provided on the first surface 60a of the third substrate 60 in the first embodiment are provided. Is provided. Further, an alignment film is provided on the second liquid crystal layer 31B side of each of the substrates 160 and 170 so as to cover the above-described electrodes.

  The operation of the optical pickup in the second embodiment is merely that the first liquid crystal element 30A in the first embodiment is changed to the first liquid crystal element 130A, and the second liquid crystal element 30B in the first embodiment is changed to the second liquid crystal element 130A. Since it is not different from the operation of the optical pickup in the first embodiment, the description is omitted here.

  As described above, the two liquid crystal elements constituting the phase modulation device may be provided independently.

  In each of the embodiments described above, the concentric first electrode and the second electrode formed in the liquid crystal element constituting the phase modulation device are divided into a plurality of regions, and the electrodes are connected by a high resistance line. Although it has a structure, it is not limited to such a structure.

  For example, as shown in FIG. 19 (a), a plurality of concentric (three in this case) low resistance electrode 258 composed of 258a to 258c, one high resistance electrode 259, and low resistance electrodes 258a, 258b, 258c. Power supply wirings 251, 252, and 253 that supply voltages to each may be provided. Also in this case, similarly to the above-described embodiment, the region corresponding to the power supply wiring region 257 where the supply wirings 251 to 253 are provided has the rotation direction (tangential direction) and the radial direction (radial direction) in the optical disc. What is necessary is just to provide so that it may be located in the direction of between.

  In the above-described embodiment, the power supply wiring is electrically connected to some of the concentric electrodes and the high resistance line is provided, but as shown in FIG. An electrode 358 including a plurality of concentric (here, six) electrodes 358a to 358f may be provided, and power supply wirings 351 to 356 for supplying a voltage to each of the electrodes 358a to 358f may be provided. Also in this case, as in the above-described embodiment, the portion corresponding to the power supply wiring region 357 where the power supply wirings 351 to 356 are provided is in the rotation direction (tangential direction) and the radial direction (radial direction) of the optical disc. What is necessary is just to provide so that it may be located in the direction of between.

  In each of the above-described embodiments, it is possible to drive the two liquid crystal elements A and B for correcting the aberrations for going and returning integrally with the objective lens 6, which is desirable. That is, when the objective lens 6 is driven in the tracking direction, the center of the liquid crystal element is decentered, which may cause aberration. Therefore, this can be prevented by integral driving. In each of the above-described embodiments, an optical disk has been described as an example of an optical recording medium. However, the present invention is not limited to this, and can be similarly applied to a system such as an optical card or a magneto-optical disk. In the present invention, the optical pickup is not limited to one in which the light source and the light detector are mounted in the optical head block and moved integrally, but the light source and the light detector are fixedly arranged separately from the optical head block. The thing of the structure which was made is also included.

It is a figure which shows the structure of the optical pick-up concerning 1st Embodiment. It is a schematic perspective view of the phase modulation apparatus mounted in the optical pickup of FIG. It is a disassembled perspective view of the phase modulation apparatus of FIG. It is sectional drawing of the phase modulation apparatus cut | disconnected by line AA 'of FIG. It is a top view of the 2nd surface of the 1st board | substrate which comprises the phase modulation apparatus of FIG. It is a top view of the 1st surface of the 2nd board | substrate which comprises the phase modulation apparatus of FIG. It is a top view of the 2nd surface of the 2nd board | substrate which comprises the phase modulation apparatus of FIG. It is a top view of the 1st surface of the 3rd board | substrate which comprises the phase modulation apparatus of FIG. It is a figure explaining the tangential direction and radial direction in an optical disk. It is a fragmentary sectional view which shows the state at the time of power-off and on of a phase modulation apparatus. FIG. 6 is a diagram (No. 1) for describing a positional relationship between a light receiving region of the photodetector and a first power supply wiring provided in the first liquid crystal element in the first embodiment. It is a figure for demonstrating the positional relationship of the light-receiving area | region of the photodetector in 1st Embodiment, and the 2nd electric power feeding wiring provided in the 2nd liquid crystal element. It is a figure for demonstrating the relationship between the pit pattern provided on the optical disk, and the condensing spot condensed on an optical disk. FIG. 5 is a diagram (part 2) for explaining the positional relationship between the light receiving region of the photodetector and the first power supply wiring provided in the first liquid crystal element in the first embodiment, and is a diagram for explaining an example of the positional deviation. FIG. 6 is a diagram (No. 3) for explaining the positional relationship between the light receiving region of the photodetector and the first power supply wiring provided in the first liquid crystal element in the first embodiment, and is a diagram for explaining a misaligned example. As a comparative example, it is a diagram (No. 1) for explaining the positional relationship between the light receiving region of the photodetector and the first power supply wiring when the first power supply wiring is provided in the tangential direction. FIG. As a comparative example, it is the figure (the 1 and the 2) for demonstrating the positional relationship of the light-receiving area | region of a photodetector when a 1st electric power feeding line is provided in a tangential direction, and the 1st electric power feeding wiring, The example which carried out position shift It is a figure explaining. It is a figure which shows the structure of the optical pick-up concerning 2nd Embodiment. It is a top view which shows the other shape of the electrode formed in the liquid crystal element which comprises a phase modulation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser light source 3 ... Polarizing beam splitter 5 ... 1/4 wavelength plate 8 ... Optical disk 10, 110 ... Optical pick-up 30, 130 ... Phase modulation apparatus 30A, 130A ... 1st liquid crystal element 30B, 130B ... 2nd liquid crystal element 31A ... 1st liquid crystal 31B ... 2nd liquid crystal 40 ... 1st board | substrate 50 ... 2nd board | substrate 51 ... 1st A electric power feeding wiring 52 ... 1B power supply wiring 57 ... 1st power supply wiring area 58 ... 1st electrode 60 ... 3rd board | substrate 70 ... Photo detector 71A-71D ... Light receiving area 80 ... Rotation direction (Tangential direction)
81 ... Radial direction (radial direction)
86 ... Condensation spot 140, 150, 160, 170 ... Substrate 151 ... Second A power supply wiring 152 ... Second B power supply wiring 157 ... Second power supply wiring region 158 ... Second electrode 251 to 253, 351 to 356, ..feed wiring 258, 358 ..electrode

Claims (11)

A light source for emitting light to a rotating optical recording medium;
A photodetector for detecting reflected light of the light emitted from the light source with respect to the optical recording medium;
A first liquid crystal element for phase modulation provided in a first optical path from the light source to the optical recording medium and having a first electrode and a first power supply wiring electrically connected to the first electrode. In optical pickup,
In the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the light spot and is located in the direction between the rotation direction and the radial direction of the optical recording medium. The optical pickup further includes the first power supply wiring. The optical pickup according to claim 1,
A phase modulation second liquid crystal element having a second electrode and a second power supply wiring electrically connected to the second electrode, provided in a second optical path from the optical recording medium to the photodetector; Features an optical pickup. The optical pickup according to claim 2,
The second liquid crystal element is provided in the first optical path;
The optical pickup, wherein the first liquid crystal element and the second liquid crystal element are arranged so that the first power supply wiring and the second power supply wiring overlap in a plane. The optical pickup according to claim 2,
A region corresponding to the first power supply line in a light spot emitted from the light source, passing through the first liquid crystal element, reflecting the optical recording medium, and irradiated to the photodetector, and emitted from the light source, Light that reflects from the optical recording medium, passes through the second liquid crystal element, and coincides with a region corresponding to the second power supply wiring in a light spot that is irradiated onto the photodetector. pick up. The optical pickup according to claim 2,
An objective lens for condensing the light emitted from the light source on the information recording surface of the optical recording medium;
A quarter-wave plate disposed between the light source and the objective lens;
An optical branching element that is disposed between the light source and the quarter-wave plate and that guides light from the light source to the optical recording medium side and guides reflected light from the optical recording medium to the photodetector. ,
The first liquid crystal element is disposed between the light source and a quarter-wave plate; the second liquid crystal element is disposed between the quarter-wave plate and a photodetector;
In the optical spot irradiated to the photo detector, an area corresponding to the first power supply wiring and an area corresponding to the second power supply wiring area coincide with each other. The optical pickup according to claim 2,
The photodetector is divided into a plurality of light receiving areas,
In the light spot irradiated to the photodetector, a region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring are located in the light spot irradiated to the photodetector, and each of the plurality of light receiving regions The optical pickup is characterized in that the first power supply wiring and the second power supply wiring are arranged so as to be located in a predetermined light receiving region. The optical pickup according to claim 2,
The photodetector has a plurality of light receiving areas divided along a rotational direction and a radial direction in the optical recording medium,
In the light spot irradiated to the photodetector, a region corresponding to the second power supply wiring is located in the light spot irradiated to the photodetector, and in an orientation between the rotation direction and the radial direction of the optical recording medium. The optical pickup, wherein the second power supply wiring is disposed so as to be positioned. An optical pickup comprising: a light source that emits light to a rotating optical recording medium; and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. A phase modulator provided in the first optical path leading to
A pair of substrates;
A liquid crystal layer provided between the pair of substrates;
A first electrode provided on the substrate;
A first power supply wiring electrically connected to the first electrode;
In the light spot irradiated to the optical recording medium, the region corresponding to the first power supply wiring is located in the light spot and is located in the direction between the rotation direction and the radial direction of the optical recording medium. And the first power supply wiring is arranged. An optical pickup comprising: a light source that emits light to a rotating optical recording medium; and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. A phase modulation apparatus comprising: a first liquid crystal element provided in a first optical path leading to a second liquid crystal element provided in a second optical path extending from a recording medium to a photodetector;
The first liquid crystal element has a first electrode and a first power supply wiring electrically connected to the first electrode, and the second liquid crystal element is electrically connected to the second electrode and the second electrode. A second power supply wiring connected to
In the light spot irradiated on the optical recording medium, a region corresponding to the first power supply wiring is located in the light spot irradiated on the optical recording medium, and the rotation direction and the radial direction of the optical recording medium are Located in the direction between
In the light spot irradiated to the photodetector, a region corresponding to the first power supply wiring and a region corresponding to the second power supply wiring are respectively positioned in the direction between the rotation direction and the radial direction of the optical recording medium. As described above, the phase modulation device is characterized in that the first power supply wiring and the second power supply wiring are arranged. An optical pickup comprising: a light source that emits light to a rotating optical recording medium; and a photodetector that is divided into a plurality of light receiving regions that detect reflected light of the light emitted from the light source to the optical recording medium. A phase modulator comprising: a first liquid crystal element provided in a first optical path from the light source to the optical recording medium; and a second liquid crystal element provided in a second optical path from the optical recording medium to the photodetector. There,
The first liquid crystal element has a first electrode and a first power supply wiring electrically connected to the first electrode, and the second liquid crystal element is electrically connected to the second electrode and the second electrode. A second power supply wiring connected to
In the light spot irradiated on the optical recording medium, a region corresponding to the first power supply wiring is located in the light spot irradiated on the optical recording medium, and the rotation direction and the radial direction of the optical recording medium are The first power supply wiring is provided so as to be located between
In the light spot irradiated to the photodetector, the region corresponding to the first power supply wiring and the region corresponding to the second power supply wiring are respectively positioned in a predetermined light receiving region among the plurality of light receiving regions. A phase modulation apparatus comprising a first power supply wiring and the second power supply wiring. An optical pickup comprising: a light source that emits light to a rotating optical recording medium; and a photodetector that detects reflected light of the light emitted from the light source to the optical recording medium. And a phase modulation device provided in the optical path from the optical recording medium to the photodetector,
A first substrate, a second substrate, and a third substrate arranged in order with a predetermined gap;
A first liquid crystal layer sandwiched between the first substrate and the second substrate;
A second liquid crystal layer sandwiched between the second substrate and the third substrate;
A first electrode disposed on a surface of the first substrate or the second substrate on the first liquid crystal layer side, and a first power supply wiring electrically connected to the first electrode;
A second electrode disposed on a surface of the second substrate or the third substrate on the second liquid crystal layer side, and a second power supply wiring electrically connected to the second electrode,
In the light spot irradiated on the optical recording medium, a region corresponding to the first power supply wiring is located in the light spot irradiated on the optical recording medium, and the rotation direction and the radial direction of the optical recording medium are The first power supply wiring is arranged so as to be located between
The phase modulation device is characterized in that the first power supply wiring and the second power supply wiring overlap in a plane.

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