JP4532482B2 - Double liquid crystal aberration correction element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a liquid crystal aberration correction element used for correcting an aberration occurring in recording / reproduction with an optical pickup in an optical disc apparatus. In particular, a blue-violet semiconductor laser is used as a light source, and it is preferably used for a large-capacity next-generation optical disc (BD) having a plurality of recording layers. The present invention belongs to a technical field of a liquid crystal aberration correcting element and a manufacturing method thereof.

  Conventionally, various optical discs such as CD and DVD are known as information recording media. Since these optical discs generate aberrations (distortion of the condensing spot) due to thickness deviation or warping caused by rotation, it is required to correct the aberrations and improve recording / reproducing accuracy.

As a technique for correcting the aberration, a method of driving a collimator lens with an actuator and a method of using a liquid crystal aberration correction element are known.
In the former method, an actuator is required, so that the optical pickup becomes complicated, and there is a problem that it cannot cope with high-precision correction.
On the other hand, in the liquid crystal aberration correction element, the electrodes of the liquid crystal panel are formed in, for example, a concentric ring shape, thereby performing different phase control between the central portion and the outer edge portion of the light beam. Since this liquid crystal aberration correcting element is disposed on the same optical axis as the objective lens in the optical pickup, it has been desired to reduce the size and weight so that good driving can be obtained.

  In recent years, large-capacity optical discs such as Blu-ray discs (BD) have been developed as the light source wavelength is shortened and the objective lens has a high NA. Since this BD will have multiple recording layers in the thickness direction in the future, it will be necessary to adjust the focal position of the laser to different depths, and since the light source wavelength is short, variations in cover layer thickness and disc tilt There is a tendency that the amount of wavefront aberration that occurs is small and the wavefront aberration that occurs is large. In order to cope with this problem, a double liquid crystal aberration correcting element has been proposed in which two of the above-described elements are combined and aberration correction in the forward path and the backward path is performed to improve detection accuracy.

  As a conventional double liquid crystal aberration correction element, for example, in Patent Document 1, an outgoing path of outgoing light from a light source to a magneto-optical recording medium and a return path from the magneto-optical recording medium to a photodetector are shared. Two phase correction elements are installed. Each phase correction element includes a pair of transparent substrates with transparent electrodes, and a liquid crystal layer is sandwiched between the pair of transparent substrates. The transparent electrode formed on at least one of the two phase correction elements at the time of application is a divided electrode divided so that the wavefront aberration of the emitted light can be corrected, and the substantial retardation of the two phase correction elements An example is described in which the alignment directions of the liquid crystal molecules of the liquid crystal layers constituting the two phase correction elements are orthogonal to each other when the values are equal and no voltage is applied.

In the above-described conventional element, as shown in FIG. 2 of (Patent Document 1), the substrate on one side of the element is made longer to form an electrode lead part, and the electrode lead part and the control circuit are flexible printed. It was connected by a substrate or the like.
In this case, since force is applied to the electrode lead-out portion on the glass substrate, there is a risk that cracking and chipping may occur if the glass substrate is made thin. Therefore, the thickness is limited in terms of strength (0.3%). About 0.5 mm). Therefore, when the two elements are combined, the whole becomes thick, and a sufficient weight reduction cannot be achieved. In addition, since the substrate on one side is formed long, there is a problem that the device becomes larger by that amount, and further, the weight balance of the device itself is lost, so that it is difficult to drive with high accuracy.

  Further, the liquid crystal aberration correction element is required to achieve a storage temperature range of −40 to 90 ° C. and a use temperature range of −20 to 80 ° C., particularly when considering applications such as in-vehicle use. When the liquid crystal and the substrate change, the expansion and contraction of the liquid crystal and the substrate are different. At this time, the expansion rate of the liquid crystal and the substrate is different. Therefore, when the substrate is formed long on one side as in the above (Patent Document 1) As a result, there is a possibility that the whole is deformed unevenly, and as a result, the obtained correction effect is adversely affected.

Furthermore, when manufacturing a conventional element, two substrates having different sizes are made to face each other, and liquid crystal is injected and sealed from a gap on the side surface of the substrate. Therefore, it is necessary to fabricate a combination of small substrates processed to a size of several millimeters one by one, and to inject and seal liquid crystal on each of them, resulting in poor production efficiency and high cost. . Further, two types of elements having different alignment directions of the liquid crystal molecules with respect to the positions of the electrode lead portions provided on the side had to be separately manufactured, resulting in poor efficiency.
In addition, as described above, since the electrode lead-out portion is provided so as to protrude to the side of the element, it is necessary to inspect the product for each finally processed element, and there is a problem that the efficiency is low. It was.

On the other hand, in order to perform good correction, it is ideal to add an opposite phase difference to the generated aberration. However, for example, when the electrode region is divided concentrically as in (Patent Document 2), there is a problem that the obtained phase difference is stepped.
Therefore, it has been desired to develop a double liquid crystal aberration correction element capable of linearly correcting the generated aberration.

JP 2002-319202 A (Claim 1, paragraph 0038, FIG. 2) JP 2002-237077 A (Claim 1, paragraph 0014)

Therefore, an object of the present invention is to provide a novel double liquid crystal aberration correcting element that can be reduced in size and weight as compared with a conventional element.
It is another object of the present invention to provide a double liquid crystal aberration correcting element that linearly corrects an aberration caused by a thickness shift of an optical disk and the like, thereby improving recording / reproducing accuracy.

  It is another object of the present invention to provide a double liquid crystal aberration correction element that can maintain the performance of the element without causing non-uniform deformation due to temperature changes.

  It is another object of the present invention to provide a method for manufacturing a double liquid crystal aberration correcting element that is excellent in production efficiency, low in cost, and capable of efficiently inspecting an element.

In order to solve the above-mentioned problems, the present invention comprises two liquid crystal aberration correction elements stacked in the thickness direction, and each liquid crystal aberration correction element has a common electrode on one side and a segment electrode on the other side. The segment electrode includes a pair of substrates and a liquid crystal sandwiched between the pair of substrates, and the segment electrode has a plurality of non-electrode portions having a size and / or an arrangement interval depending on a position on the segment electrode. The liquid crystal is configured to be non-uniformly oriented when a voltage is applied inside the non-electrode portion, and a plurality of holes are formed in the thickness direction in each of the pair of substrates. A terminal connected to either the common electrode or the segment electrode is provided in the hole, and an injection port for injecting liquid crystal is formed in one of the pair of substrates, and when no voltage is applied The alignment direction of the definitive liquid crystal to provide a dual liquid crystal aberration correcting element formed by orthogonal two liquid crystal aberration correcting element.

  According to the above configuration, in addition to the above-described operation, a weak electric field is formed in the vertical direction with respect to the electrode at the center of the formed non-electrode part, and the electric field is inclined at the end of the non-electrode part. Since the liquid crystal molecules are non-uniformly aligned along the electric field distribution, a lens effect is obtained in which the refractive index continuously changes from the center to the periphery of the non-electrode part. Therefore, by allowing the light beam to pass through the lens portion, a predetermined phase difference is given and the aberration is corrected. In particular, by changing the size or arrangement interval of the non-electrode portions, the phase difference obtained in each region changes, and the entire element is optimally corrected according to the aberration.

  According to the present invention, in the double liquid crystal aberration correcting element described above, the substrate is formed in a quadrangular shape, the liquid crystal is sealed along a circular region through which the light flux of the substrate passes, and near the corner portion other than the circular region. In addition, a liquid crystal injection port and a terminal are provided.

  According to the above configuration, the vicinity of the corner portion of the substrate is effectively used as a space for forming a hole, and the weight balance of the element is improved. Further, when the liquid crystal expands / contracts, the whole is uniformly deformed.

  Further, according to the present invention, in the dual liquid crystal aberration correction element described above, terminals connected to the common electrode of each of the stacked liquid crystal aberration correction elements, terminals connected to the segment electrode of one liquid crystal aberration correction element , And terminals connected to the segment electrodes of the other liquid crystal aberration correction element are connected to each other in the thickness direction, and are integrated into terminals provided on one substrate located outside the double liquid crystal aberration correction element, respectively. It is characterized by that.

  Further, according to the present invention, in the dual liquid crystal aberration correction element described above, terminals connected to the common electrode of each of the stacked liquid crystal aberration correction elements, terminals connected to the segment electrode of one liquid crystal aberration correction element , And terminals connected to the segment electrodes of the other liquid crystal aberration correction element are connected to each other in the thickness direction, and are integrated into terminals provided on one substrate located outside the double liquid crystal aberration correction element, respectively. It is characterized by that.

  According to the said structure, each terminal for driving an element is concentratedly arranged on one board | substrate.

  Further, according to the present invention, in the double liquid crystal aberration correction element described above, a terminal connected to the segment electrode of one liquid crystal aberration correction element and a terminal connected to the segment electrode of the other liquid crystal aberration correction element, It is provided in the vicinity of a corner portion located diagonally of a rectangular substrate, and a terminal connected to the common electrode and a liquid crystal injection port are provided in the vicinity of the remaining corner portion.

  According to the above configuration, the position of each terminal is set in consideration of the efficiency in manufacturing the element.

  The present invention also provides a method for manufacturing a double liquid crystal aberration correction element as described above, comprising a step of providing terminals and injection ports corresponding to a large number of liquid crystal aberration correction elements on a base substrate, and a segment. A step of forming an electrode, a step of providing a terminal at a position opposite to the substrate on which the terminal, the injection port, and the segment electrode are formed and combining another substrate on which a common electrode is formed, and an injection port after the combination The liquid crystal is injected from the above and a group in which a large number of liquid crystal aberration correction elements manufactured through the above steps are arranged, and another set obtained through the same steps is turned over and rotated 90 degrees. And a step of dividing into individual double liquid crystal aberration correcting elements, and a method of manufacturing a double liquid crystal aberration correcting element.

  According to another aspect of the present invention, there is provided a method of manufacturing the double liquid crystal aberration correction element as described above, the step of providing a terminal corresponding to a large number of liquid crystal aberration correction elements on a base substrate, and the formation of segment electrodes. And a step of providing a terminal and a further injection port at opposite positions with respect to the substrate on which the terminal and the segment electrode are formed, and combining another substrate on which the common electrode is formed, and after combining the liquid crystal from the injection port And a set in which a large number of liquid crystal aberration correction elements manufactured through the above steps are arranged, and another set obtained through the same steps is turned over and rotated 90 degrees. And a method of manufacturing a double liquid crystal aberration correction element comprising: a step of separating each of the liquid crystal aberration correction elements into individual double liquid crystal aberration correction elements.

  According to the above means, the manufacture of the double liquid crystal aberration correcting element is advanced in the state of the substrate as the base material until the final process. Then, the two liquid crystal aberration correction elements for the forward path and the return path in which the alignment directions of the liquid crystals are orthogonal are manufactured by the same process.

  Further, according to the present invention, in the manufacturing method described above, an inspection wiring connected to each terminal is formed on the surface of the substrate, and a plurality of liquid crystal aberration correction elements are arranged. Then, the inspection is performed using the wiring at one or both of the time before the step of laminating another set or before the step of dividing into individual double liquid crystal aberration correction elements.

  According to the above means, the operation of the element is checked at a time in the state of the base material before being divided into individual elements.

  In addition, in the manufacturing method according to any one of the above, the present invention provides a circular region through which a light beam passes in a vacuum when another set is stacked on a set in which a large number of liquid crystal aberration correction elements are arranged. It is characterized by laminating through a sealing material provided in a closed state so as to surround.

  According to the above means, a high light transmittance is maintained because the two liquid crystal aberration correcting elements are in a vacuum state and no adhesive is present.

  Furthermore, in the manufacturing method according to any one of the above, the present invention provides a circular region through which a light beam passes in the atmosphere when another set is stacked on a set in which a large number of liquid crystal aberration correction elements are arranged. It is characterized by laminating via a sealing material provided in a partially opened state so as to surround and an adhesive provided inside the sealing material.

  According to the above means, the step of laminating the two liquid crystal aberration correction elements is efficiently performed in the atmosphere. In this case, it is preferable to select an adhesive having a refractive index close to that of the substrate.

  Since the double liquid crystal aberration correcting element of the present invention has a hole in the surface of the substrate and the hole is used as a terminal, an excessive force is applied to the substrate as compared with the conventional element in which the terminal is provided on the side. Absent. Therefore, a thinner substrate can be employed, and as a result, the weight of the device can be reduced.

  Further, by arranging the terminals on the surface of the substrate, the device can be reduced in size accordingly.

  Further, when a plurality of non-electrode portions are formed in the segment electrode, the lens effect is produced by aligning liquid crystal molecules along a non-uniform electric field distribution formed at the positions of the non-electrode portions. As a result, it is possible to linearly correct the aberration caused by the thickness deviation of the optical disk.

  In addition, liquid crystal is sandwiched in the center of a square substrate and terminals are provided at the corners of the substrate, providing excellent weight balance of the device and non-uniform deformation even when the liquid crystal expands or contracts due to temperature changes. Does not occur, and the performance of the device can be maintained.

Further, according to the method for manufacturing a double liquid crystal aberration correcting element of the present invention, the process of forming the terminal, the process of injecting the liquid crystal, and the like are performed in the state of the base material before all the individual elements are separated. Production efficiency is improved and costs can be significantly reduced.
In addition, when inspecting each element, since it can be performed in the state of the base material, high efficiency can be achieved.
Furthermore, two liquid crystal aberration correction elements to be laminated can be manufactured in exactly the same process, and a double element in which the alignment directions of liquid crystals are orthogonal can be easily manufactured by turning one over and rotating 90 degrees. it can. Therefore, productivity is extremely high and stable quality can be obtained.

It is a top view which shows one Embodiment of the double liquid-crystal aberration correction element which concerns on this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is an enlarged view of S part of FIG. It is a figure explaining the orientation state of the liquid crystal at the time of applying a voltage. It is a flowchart which shows the manufacturing process of a double liquid-crystal aberration correction element. It is a flowchart which shows the manufacturing process of a double liquid-crystal aberration correction element. It is a figure which shows the state of S103 in a P direction. It is sectional drawing of the terminal part which shows the state of S103. It is a figure which shows the state of S106 in a P direction. It is a figure which shows the state of S108 in a P direction. It is a figure which shows the state of S205 in Q direction. It is a figure which shows the state of S104 in a R direction. It is a figure which shows the state of S501. It is a figure which shows the state of S305. It is a figure which shows the state of S504. It is a figure which shows another embodiment of the state of S305.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double liquid crystal aberration correction element 1A, 1B Liquid crystal aberration correction element 10, 11 Board | substrate 101 Corner part 20 Common electrode 21 Segment electrode 211 Non-electrode part 30A-30F Hole 31A-31F Terminal 40 Liquid crystal 50, 51, 51A Sealing material 52 Adhesion Agent 60 Inlet 61 Sealing material 70 Conductive material 80 Mask 90 Wiring 100, 110 Substrate serving as a base material

Hereinafter, the best mode for carrying out the present invention will be described in detail.
FIG. 1 is a plan view of an embodiment of a double liquid crystal aberration correcting element according to the present invention. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. As shown in FIGS. 1 to 3, the double liquid crystal aberration correction element 1 is formed by laminating two liquid crystal aberration correction elements 1 </ b> A and 1 </ b> B having the same configuration in the thickness direction through a conductive material 70 and a seal material 51. It is comprised by letting. The liquid crystal aberration correcting element 1A (same for 1B) is schematically configured by sandwiching the liquid crystal 40 between the substrate 10 on which the common electrode 20 is formed and the substrate 11 on which the segment electrode 21 is formed. In addition, a liquid crystal alignment film generally provided between the common electrode 20 and the liquid crystal 40 and between the segment electrode 21 and the liquid crystal 40, a transparent insulating layer, an antireflection film provided on the substrates 10 and 11, etc. The illustration is omitted. Further, the liquid crystal 40 is sealed inside by a sealing material 50.

  The double liquid crystal aberration correction element 1 allows a light beam to pass through a region where the liquid crystal 40 is provided, and applies a voltage between the common electrode 20 and the segment electrode 21 at that time, thereby changing the position in the region. The alignment state of different liquid crystals 40, that is, a phase difference is given, thereby correcting light aberration. At this time, since the liquid crystal aberration correction elements 1A and 1B have the alignment directions of the liquid crystal 40 orthogonal to each other when no voltage is applied, the aberrations in the forward and return paths can be corrected well.

Here, the configuration of the segment electrode 21 will be described in detail.
In this embodiment, as shown in FIG. 4 which is a partially enlarged view of S in FIG. 1, the segment electrode 21 is formed with a plurality of non-electrode portions 211 having no electrode material in a hole shape. The plurality of non-electrode portions 211 are continuously changed in size and arrangement interval depending on the position on the segment electrode 21. Although the number of the non-electrode portions 211 is illustrated as small in FIG. 4 for the sake of convenience, a large number of non-electrode portions 211 are actually formed more finely. In this embodiment, along the radial direction r of the segment electrode 21, the arrangement electrode d2 is wide so that the size d1 of the non-electrode portion 211 is once changed from a large diameter to a small diameter and becomes a large diameter again. A continuous pattern is formed so that the interval once becomes narrower than the interval and then becomes wider again.

  When a voltage is applied between the common electrode 20 and the segment electrode 21, the state of the electric field E in the vicinity of the non-electrode portion 211 is as shown in FIG. That is, in the portion a where the common electrode 20 and the segment electrode 21 face each other, a strong electric field is formed in the direction perpendicular to the electrode, and in the portion b that is the central portion of the non-electrode portion 211, the direction perpendicular to the electrode is also formed. A weak electric field is formed. Then, in a portion c close to the boundary between the non-electrode portion 211 and the segment electrode 21, the electric field is inclined toward the segment electrode 21.

Then, when the dielectric anisotropy of the liquid crystal 40 is positive, since the liquid crystal molecules are aligned along the electric field E, the liquid crystal molecules are aligned perpendicular to the electrodes in the portion a, and the electric field is weak in the portion b. The state remains parallel to the electrode, and the portion c is oriented obliquely. That is, the liquid crystal 40 is in a non-uniform alignment state inside the non-electrode portion 211. At this time, the refractive index for light passing through the element (abnormal light) forms a distribution that continuously decreases from the center of the non-electrode portion 211 toward the periphery, and therefore the effect of the convex lens in the non-electrode portion 211 portion. Will be shown. Thereby, a phase difference can be given to the passing light.
Therefore, when the size and arrangement interval of the non-electrode portions 211 are continuously changed depending on the positions on the segment electrodes 21, the phase difference obtained at each position is different. By appropriately designing the arrangement pattern, the aberration can be linearly corrected for the entire element.

  In addition, when the voltage to apply is changed, the orientation state of a liquid crystal molecule changes according to it. For example, when the voltage is increased, the liquid crystal molecules are vertically aligned even at the center of the non-electrode portion 211, and conversely, a concave lens effect is exhibited in which the refractive index increases from the center to the periphery of the non-electrode portion 211. . In other words, the phase difference curve obtained for the entire device can be changed by the applied voltage. For example, the correction amount is calculated based on the reproduction (RF) waveform, and the voltage is controlled according to the result. It is also possible to correct the aberration to be performed in real time.

  In the example of FIG. 4, the size and arrangement interval of the non-electrode portions 211 are changed along the radial direction r. In this way, a phase difference curve that changes concentrically in accordance with the arrangement pattern of the non-electrode portions 211 is obtained, so that it is possible to satisfactorily correct the spherical aberration caused by the disc thickness deviation. In addition, since the size and the arrangement interval of the non-electrode portion 211 are continuously changed, the linear correction is not linear rather than the stepwise discontinuous correction as in the conventional aberration correction element in which the segment electrodes are divided concentrically. Correction is possible.

Furthermore, the arrangement interval of the non-electrode portions 211 is preferably irregular (random arrangement) within each region (for example, the region M and the region N) when the segment electrode 21 is concentrically divided. That is, as shown in FIG. 4, the arrangement intervals h1 and h2 are slightly different. In this way, it is possible to prevent a situation in which light passing through adjacent non-electrode portions interferes with each other and disturbs the wavefront.
If it is expected that there will be almost no interference effect due to the relationship between the wavelength of light and the arrangement interval, h1 and h2 may be arranged regularly.

  Further, as a method of forming the non-electrode portion 211, a method in which an electrode material is first formed on the entire surface of the substrate 11 and then a plurality of non-electrode portions 211 are formed in a desired arrangement pattern by a photo process is preferably used. . In this way, it is possible to easily create a fine arrangement pattern that changes continuously. Alternatively, a method of performing through a mask when the segment electrode 21 is vapor-deposited or plated on the substrate 11 may be used.

  Next, as the substrates 10 and 11, a transparent substrate such as a glass substrate is used. Moreover, as the common electrode 20 and the segment electrode 21, a transparent electrode such as ITO having an indium-tin oxide film formed thereon is appropriately employed.

  In this embodiment, holes 30A, 30B, and 30C are formed in the thickness direction of the substrate 11, and holes 30D, 30E, and 30F are formed in the substrate 10 as well. Terminals 31A, 31B, 31C, 31D, 31E, and 31F for connecting to the common electrode 20 and the segment electrode 21 are provided in the respective holes. That is, the terminals 31A and 31D are connected to the segment electrode 21 of the liquid crystal aberration correction element 1A, the terminals 31B and 31E are connected to the common electrode 20, and the terminals 31C and 31F are connected to the segment electrode 21 of the liquid crystal aberration correction element 1B. The opposing terminals (for example, the terminal 31B and the terminal 31E) are connected with the conductive material 70 interposed therebetween. Each terminal is formed by plating a metal such as Ni—Au along the inner peripheral surface of the hole.

  By arranging the terminals on the surfaces of the substrates 10 and 11 as described above, it is possible to crack without applying a biased force to the elements as compared with the conventional elements in which the terminals are concentrated on the side of the substrate.・ Defects such as chipping are less likely to occur. Accordingly, the substrates 10 and 11 can be made thinner (for example, 0.2 mm), and the element can be reduced in weight. Specifically, 40% or more compared to the conventional case (the effect of changing from the conventional terminal to the terminal arranged on the surface is about 10%, the effect of changing the thickness of the substrate from 0.3 mm to 0.2 mm is about 33%).

In this embodiment, an injection port 60 for injecting the liquid crystal 40 between the substrates 10 and 11 is formed on the surface of the substrate 11. The shape of the inlet 60 is circular, elliptical, or the like, and is appropriately sealed with a sealing material 61 after the liquid crystal 40 is injected.
In particular, in the example of FIG. 1, all of the terminals 31 </ b> A to 31 </ b> F and the liquid crystal injection port 60 are disposed on the surfaces of the substrates 10 and 11, and the opposing terminals are connected to each other in the thickness direction. Since the liquid crystal aberration correction element 1A is concentrated at each driving terminal, the element production efficiency can be increased as described later.

  Further, in the example of FIG. 1, the holes 30 </ b> A to 30 </ b> F and the liquid crystal injection port 60 are formed in a rectangular shape other than the circular region through which the light beam passes (the region where the segment electrode 21 and the common electrode 20 are formed). It is formed in the vicinity of the corner portion 101 on the substrate 11 (10). Further, the sealing material 50 is provided in a substantially circular shape, and the liquid crystal 40 is sealed in a circular region through which the light beam passes. In this way, since the surplus portion on the substrate 11 through which the light beam does not pass can be used effectively as the position of the terminal or the like, the element can be further downsized. Further, by arranging the terminals and the like in the corner portion 101, the weight balance of the element can be optimized. As a result, it is possible to drive with high accuracy, and when the liquid crystal expands and contracts due to a temperature change, pressure is applied uniformly to the substrate 11 so that non-uniform deformation does not occur and the device performance is maintained. Can do.

  Note that in a conventional element using liquid crystal (such as a liquid crystal display element), it is required to make the frame portion (the surplus portion of the substrate) as narrow as possible with the expansion of the display area. In addition, since the number of terminals tends to increase corresponding to the high-division driving method or the like, there is no idea of effectively using the corner portion of the substrate, which can be said to be unique to the present invention.

  Note that the arrangement pattern of the plurality of non-electrode portions 211 is not limited to the above embodiment. That is, according to the aberration etc. which generate | occur | produce, the magnitude | size or arrangement | positioning space | interval of the non-electrode part 211 or both can be suitably set with the position on the segment electrode 21. FIG. Specifically, for example, the case where the size of the non-electrode portion is continuously changed from the small diameter to the large diameter and the small diameter from the center to the periphery of the segment electrode 21 contrary to FIG. It is done. In addition, the size and the arrangement interval are not limited to being concentrically changed on the segment electrode 21, but for example, when the segment electrode 21 is divided into left and right areas, the arrangement patterns are formed so as to be different in the respective areas. May be. In this case, coma caused by the warp of the disk can be effectively corrected.

  In the above-described embodiment, the case where the shapes of the plurality of non-electrode portions 211 are circular has been described. However, the present invention is not limited to this. Can be. Specific examples include an elliptical shape and a semicircular shape.

  In the example of FIG. 1, the pattern of the segment electrode 21 is formed so as to be directly connected to the terminal 31 </ b> A. In addition to this, for example, after forming each electrode pattern composed of a closed circular region, Each electrode and each terminal may be connected by a lead wire or the like.

  Note that the terminals provided on the substrates 10 and 11 are connected to each other in the thickness direction and concentrated on the terminals on the uppermost substrate. Although the case where the part 211 is formed has been described as an example, the present invention is not limited to this. Also in this case, the device can be reduced in size and weight by arranging the terminals on the substrate. Alternatively, the segment electrode may be divided into left and right. In this case, it is possible to satisfactorily correct coma generated by warping of the optical disk.

The double liquid crystal aberration correcting element 1 as described above constitutes an optical pickup together with, for example, a laser light source, a polarizer, a half-wave plate, a quarter-wave plate, an objective lens, a light receiving element, and the like, and is incorporated in an optical disc apparatus. Can be used.
In particular, since aberrations in the forward and return paths can be corrected, it can be suitably used for next-generation BD (Blu-ray Disc) and high-density optical disks such as multilayer disks.

  Next, a method for manufacturing the double liquid crystal aberration correcting element 1 according to the example of FIG. 1 will be described with reference to FIGS.

  First, processing steps of the substrate 11 in the liquid crystal correction element 1A will be described in order. 8 to 11 show states viewed from the P direction in FIG. First, as shown in FIGS. 6 and 8, holes 30A, 30B, 30C corresponding to a large number of liquid crystal aberration correction elements and a liquid crystal injection port 60 are formed at predetermined positions on a substrate 110 serving as a base material. (S101). Subsequently, after an antireflection film (AR film) is formed on the entire surface of the substrate 110 serving as a base material (S102), terminals 31A, 31B, and 31C are provided in the respective holes (S103). As will be described later, since the terminals 31A to 31C need to overlap each other when the substrate 110 is turned upside down and rotated 90 degrees, the substrate 110 which is a base material is preferably a square and is arranged in a large number. The same number of liquid crystal aberration correction elements are formed in the vertical and horizontal directions. In addition, when providing each terminal (for example, terminal 31A), as shown in FIG. 9, after forming the mask 80 in parts other than the hole 30A, after forming the metal used as the terminal 31A by plating etc., mask This is preferably done by removing 80.

  Subsequently, on the side viewed from the R direction in FIG. 2, after forming a wiring used for inspection as described later (S104), an electrode material is formed at a predetermined position by vapor deposition (S105), and etching is performed. Patterning is performed to produce the segment electrode 21 (S106). This state is shown in FIG. Note that the above-described step of providing the terminal and the step of forming the wiring used for the inspection may be mixed.

  Next, a transparent insulating layer is laminated on the P direction side as necessary, a liquid crystal alignment film such as PVA is formed, and rubbing is performed (S107). Further, a sealing material 50 for enclosing the liquid crystal is provided outside the segment electrode 21 by printing or the like (S108). This state is shown in FIG.

On the other hand, with respect to another substrate (substrate 10 side) to be opposed, as shown in FIG. 12 as viewed from the Q direction of FIG. 2, the hole 30D is formed at the same position as the substrate 110 with respect to the substrate 100 as a base material. After forming 31E and 30F (S201) and forming an AR film (S202), terminals 31D, 31E and 31F are provided (S203), electrode material is deposited (S204), patterning is performed, and common is performed. The electrode 20 is formed (S205). Further, a liquid crystal alignment film is formed and rubbed (S206), and a conductive material for connecting each terminal of the substrate 110 to be opposed is provided by printing or the like (S207).
In some cases, the injection port 60 may be formed on the substrate 10 side, or the sealing material 50 may be printed on the substrate 10 side and the conductive material may be printed on the substrate 11 side.

And the board | substrate 110 and the board | substrate 100 which formed the above terminals etc. are made to oppose, and are combined (S301). This step is performed by bonding with an adhesive via a spacer.
Subsequently, liquid crystal is injected into the sealing material 50 from the injection port 60 (S302) and sealed with a sealing material. Then, using each terminal arranged on the substrate 110 serving as a base material, an operation inspection of the element is performed (S303). At this time, since the wiring 90 is formed in advance on the substrate 110 as shown in FIG. 13 (S104), 100% inspection is performed at once using the wiring 90. NG marking is performed about the location which failed as a result of the inspection (S304).

  Through the above steps (S101 to S303), a set in which a large number of liquid crystal aberration correction elements 1A are arranged is obtained. Then, another set (the liquid crystal aberration correction elements 1B are arranged) manufactured through the same steps (S101 to S303) is stacked on this set (S501). At this time, as shown in FIG. 14, another set is turned over in the Z direction and rotated 90 degrees in the X direction, and the substrate 100 side of the set in which the liquid crystal aberration correction elements 1A are arranged, and the liquid crystal aberration correction By stacking the substrate 100 side of the set in which the elements 1B are arranged, the common terminals and the corresponding segment terminals are combined, and the liquid crystal alignment direction is orthogonal.

  Further, when the sets are stacked, the sealing material 51 and the conductive material 70 are printed in advance between the sets (S305, S401). The seal material 51 and the conductive material 70 may be provided on the liquid crystal aberration correction element 1A side or on the opposite liquid crystal aberration correction element 1B side.

  As shown in FIG. 15, the sealing material 51 can be provided in a closed state so as to surround a circular region through which the light beam passes. In this case, it is necessary to perform the operation of stacking the sets in a vacuum so that the stacked state is not impaired by the expansion of the gas confined inside the sealing material 51. It is preferable that the sealing material 51 is closed and the inside is a vacuum because dust or the like does not enter the inside and the light transmittance can be increased.

  Then, after the sets are stacked, the operation of the double liquid crystal aberration correction element is inspected using each terminal arranged on the substrate 110 as the base material (S502). Also at this time, 100% inspection can be performed at a time using the wiring 90 formed on the substrate 110 as in the case described above. NG marking is performed about the location which failed as a result of the inspection (S503).

  Finally, as shown in FIG. 16, the base material substrate is cut into individual double liquid crystal aberration correction elements 1 using a dicer or the like (S504), and is shipped after undergoing a single product inspection step (S505) ( S507). In addition, the element which failed in the inspection of a single item is discarded or repaired, or moved to a regeneration process (S506).

  In addition, when laminating a pair, instead of the sealing material 51 shown in FIG. 15, a sealing material 51 </ b> A provided in a partially opened state so as to surround a circular region through which a light beam passes is used as shown in FIG. 17. It may be interposed. In this case, an adhesive 52 is provided on the inner side of the sealing material 51 </ b> A, and the pair is bonded by the adhesive 52. In the example of FIG. 17, since the operation | work which laminates | stacks sets can be performed in air | atmosphere, there exists an advantage that production efficiency is high.

According to the manufacturing method as described above, the formation of each terminal and electrode, the liquid crystal injection process, etc. are all performed in the state of the base material before dividing into individual elements, so the production efficiency is very high and the cost is high. Can also be greatly reduced. In addition, it can easily cope with the expansion of production scale.
In particular, the two liquid crystal aberration correction elements to be stacked are manufactured in the same process rather than separately, and it is only necessary to turn one side over and rotate it 90 degrees, so that the overall production efficiency is greatly improved.
Furthermore, since the inspection process performed after injecting and sealing the liquid crystal can be performed in the same state as the base material, it is extremely useful in the industry.

Claims (12)

  The liquid crystal aberration correction elements are stacked in the thickness direction, and each liquid crystal aberration correction element is sandwiched between a pair of substrates each having a common electrode and a segment electrode on the other side, and the pair of substrates. The segment electrode is formed with a plurality of non-electrode portions where no electrode material is present by changing the size and / or the arrangement interval depending on the position on the segment electrode. The liquid crystal is configured to be non-uniformly oriented when a voltage is applied, and a plurality of holes are formed in the thickness direction in each of the pair of substrates, and any of the common electrode and the segment electrode is formed in the holes. A terminal connected to each other is formed, and an inlet for injecting liquid crystal is formed in one of the pair of substrates. Double crystal aberration correcting element formed by orthogonal correcting element. 2. The double liquid crystal aberration correcting element according to claim 1 , wherein the substrate is formed in a square shape, the liquid crystal is sealed along a circular region through which the light flux of the substrate passes, and the liquid crystal is near the corner portion other than the circular region. A double liquid crystal aberration correcting element, characterized in that an inlet and a terminal are provided. 2. The double liquid crystal aberration correction element according to claim 1, wherein terminals connected to the common electrode of each laminated liquid crystal aberration correction element, terminals connected to the segment electrode of one liquid crystal aberration correction element, and the other are connected. The terminals connected to the segment electrodes of the liquid crystal aberration correction element are connected to each other in the thickness direction, and are integrated into terminals provided on one substrate located outside the double liquid crystal aberration correction element. A double liquid crystal aberration correction element. 3. The double liquid crystal aberration correction element according to claim 2, wherein terminals connected to the common electrode of each laminated liquid crystal aberration correction element, terminals connected to the segment electrode of one liquid crystal aberration correction element, and the other are connected. The terminals connected to the segment electrodes of the liquid crystal aberration correction element are connected to each other in the thickness direction, and are respectively integrated into terminals provided on one substrate which is the outermost side of the double liquid crystal aberration correction element. A double liquid crystal aberration correction element. 5. The double liquid crystal aberration correction element according to claim 4, wherein a terminal connected to the segment electrode of one liquid crystal aberration correction element and a terminal connected to the segment electrode of the other liquid crystal aberration correction element are rectangular substrates. A double liquid crystal aberration correction element, characterized in that a terminal connected to a common electrode and a liquid crystal injection port are provided in the vicinity of the remaining corner portion. 6. The method of manufacturing a double liquid crystal aberration correction element according to claim 5, wherein a step of providing terminals and injection holes corresponding to a large number of liquid crystal aberration correction elements on a base substrate and a segment electrode are formed. A step of combining a substrate on which the terminal, the injection port, and the segment electrode are formed with a terminal on the opposite position and another substrate on which the common electrode is formed, and injecting liquid crystal from the injection port after the combination And a step in which another set obtained through the same steps is turned upside down and rotated 90 degrees with respect to a set in which a large number of liquid crystal aberration correction elements manufactured through the steps are arranged. And a step of dividing the liquid crystal aberration correction element into individual liquid crystal aberration correction elements. A method for manufacturing a double liquid crystal aberration correction element according to claim 5, wherein a step of providing terminals corresponding to a large number of liquid crystal aberration correction elements on a substrate serving as a base material, a step of forming segment electrodes, A step of providing a terminal and a further injection port at a position opposite to the substrate on which the terminal and the segment electrode are formed and combining another substrate on which a common electrode is formed, and a step of injecting liquid crystal from the injection port after the combination And, with respect to the set in which a large number of liquid crystal aberration correction elements manufactured through the respective steps are arranged, another step obtained through the same steps is turned over and rotated 90 degrees, and then laminated. A method of manufacturing a double liquid crystal aberration correction element comprising the steps of dividing the individual double liquid crystal aberration correction element. The manufacturing method according to claim 6 or 7, wherein the surface of the substrate, the wiring for inspection that are commonly connected to the respective terminals to form another respect plurality sets liquid crystal aberration correcting element arranged in The double liquid crystal aberration is characterized in that the inspection is performed using the wiring at one or both of the time before the step of laminating the set of the two or before the step of separating the individual double liquid crystal aberration correction elements. A method of manufacturing a correction element. The manufacturing method according to claim 6 or 7, wherein, when to stack another set against a large number sets liquid crystal aberration correcting element arranged in, in a vacuum, closed so as to surround the circular region in which the light flux passes A method for producing a double liquid crystal aberration correction element, wherein the liquid crystal aberration correction element is laminated through a sealing material provided in a state. 9. The manufacturing method according to claim 8 , wherein when another set is stacked on a set in which a large number of liquid crystal aberration correction elements are arranged, the set is closed in a vacuum so as to surround a circular region through which a light beam passes. A method for producing a double liquid crystal aberration correction element, wherein the lamination is performed through a sealing material provided. 8. The manufacturing method according to claim 6 or 7 , wherein when another set is stacked on a set in which a large number of liquid crystal aberration correction elements are arranged, a part is surrounded so as to surround a circular region through which a light beam passes. A method for producing a double liquid crystal aberration correcting element, comprising: laminating via a sealing material provided in an open state and an adhesive provided inside the sealing material. 9. The manufacturing method according to claim 8 , wherein when another set is stacked on a set in which a large number of liquid crystal aberration correction elements are arranged, a part of the set is opened so as to surround a circular region through which a light beam passes in the atmosphere. A method for producing a double liquid crystal aberration correcting element, comprising: laminating via a sealing material provided in a state and an adhesive provided inside the sealing material.

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