JP5836822B2 - LCD lens - Google Patents

Description

  The present invention relates to a liquid crystal lens.

  In recent years, attention has been paid to liquid crystal lenses as described in Patent Document 1 and the like. In the liquid crystal lens, the optical power can be changed by changing the voltage applied to the liquid crystal layer and changing the refractive index of the liquid crystal layer. For this reason, by using a liquid crystal lens, the optical system can be made compact or highly functional.

JP 2011-17742 A

  In expanding the application of the liquid crystal lens, it is important to improve the wavefront aberration of the liquid crystal lens.

  An object of the present invention is to provide a liquid crystal lens having a small wavefront aberration.

  The liquid crystal lens according to the present invention includes a pair of main wall portions, side wall portions, and a liquid crystal layer that are arranged to face each other. The side wall portion is disposed between the pair of main wall portions. The side wall section defines a cylindrical internal space together with the pair of main wall sections. The liquid crystal layer is disposed in the internal space. A communication hole communicating with the internal space is formed in the side wall portion. In plan view, the communication hole is provided so that the center of the internal space is not located on the extended line of the central axis of the communication hole.

  In plan view, it is preferable that the communication hole is provided so as to extend along a direction in which a tangent extends at a connection portion between the inner wall surface of the side wall portion forming the internal space and one side surface of the communication hole.

  The liquid crystal layer may be provided also at least on the inner space side portion of the communication hole.

  According to the present invention, a liquid crystal lens having a small wavefront aberration can be provided.

1 is a schematic exploded perspective view of a liquid crystal lens in an embodiment of the present invention. It is a typical top view of a liquid crystal layer and a communicating hole in one embodiment of the present invention. It is a typical top view of a liquid crystal layer and a communicating hole in a reference example.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  Moreover, in each drawing referred in embodiment etc., the member which has a substantially the same function shall be referred with the same code | symbol. The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

  FIG. 1 shows a schematic exploded perspective view of a liquid crystal lens in the present embodiment. FIG. 2 shows a schematic plan view of the liquid crystal layer and the communication hole in the present embodiment.

  As shown in FIG. 1, the liquid crystal lens 1 includes an element body 10. The element body 10 includes a plurality of glass plates 11a to 11d stacked along one direction. Adjacent glass plates 11a to 11d are opposed to each other. In the present embodiment, the glass plates 11a to 11d constitute a main wall portion.

  An electrode (not shown) and an alignment film provided on the electrode are formed on the inner main surfaces of the glass plate 11a and the glass plate 11d. On the other hand, an alignment film is formed on both main surfaces of the glass plates 11b and 11c. Electrodes may also be formed between the glass plates 11b and 11c and the alignment film.

  Each thickness of glass plate 11a-11d is not specifically limited. The glass plates 11a to 11d may have the same thickness or may be different from each other. Usually, the glass plates 11a and 11d positioned above and below are relatively thick, and the glass plates 11b and 11c positioned at the center are relatively thin. The thickness of the glass plates 11a and 11d is preferably 50 μm to 500 μm, and more preferably 100 μm to 300 μm. The thickness of the glass plates 11b and 11c is preferably 10 μm to 400 μm, and more preferably 20 μm to 200 μm.

  Sidewall portions 12 are arranged between the glass plates 11a to 11d adjacent to each other in the stacking direction. A plurality of internal spaces 18 are defined by the side wall portion 12 and the glass plates 11a to 11d constituting the main wall portion. The internal space 18 is cylindrical. A liquid crystal layer 16 is provided in each of the plurality of internal spaces 18. A voltage is applied to the liquid crystal layer 16 by an electrode provided on the glass plate 11a and an electrode provided on the glass plate 11d. As a result, the refractive index of the liquid crystal layer 16 changes. As a result, the lens power of the liquid crystal lens 1 changes.

  The thickness of the side wall portion 12 can be appropriately set according to the thickness of the liquid crystal layer 16 to be formed. The thickness of the side wall part 12 can be about 10 μm to 1000 μm, for example. From the viewpoint of improving the high-speed response of the liquid crystal lens 1, it is preferable that the liquid crystal layer 16 is thin. Therefore, the thickness of the side wall portion 12 is preferably 900 μm or less, and more preferably 800 μm or less.

  Specifically, in the liquid crystal lens 1, each of the plurality of side wall portions 12 includes a first side wall portion 12a, a second side wall portion 12b, and a third side wall portion 12c. The first side wall portion 12a is made of glass or metal. On the other hand, the 2nd and 3rd side wall parts 12b and 12c consist of resin, respectively. Each of the second and third side wall portions 12b and 12c may include, for example, a cured product of a resin adhesive such as a cured product of an ultraviolet curable resin adhesive, and spherical particles dispersed in the cured product. Good. The first side wall portion 12a is bonded to the glass plates 11a to 11d by the second or third side wall portions 12b and 12c.

  It is preferable that the thickness of each of the second and third side wall portions 12b and 12c is the same as or thinner than that of the first side wall portion 12a. The thickness of each of the second and third side wall portions 12b and 12c is more preferably 0.9 times or less the thickness of the first side wall portion 12a. However, if the thickness of the second and third side wall portions 12b and 12c is too thin, the bonding strength between the side wall portion 12 and the glass plates 11a to 11d may be too low. Therefore, the thickness of each of the second and third side wall portions 12b and 12c is preferably 0.1 times or more, more preferably 0.2 times or more the thickness of the first side wall portion 12a. .

  Specifically, the thickness of the first side wall portion 12a is preferably 10 μm to 400 μm, and more preferably 20 μm to 200 μm. The ratio of the thickness of the first sidewall portion 12a to the thickness of the sidewall portion 12 ((the thickness of the first sidewall portion 12a) / (the thickness of the sidewall portion 12)) is preferably 0.33 to 0.83. 0.40 to 0.80 is more preferable. The thickness of each of the second side wall 12b and the third side wall 12c is preferably 10 μm to 400 μm, and more preferably 10 μm to 200 μm.

  In addition, the side wall part 12 can be produced in the following manner, for example. That is, an ultraviolet curable resin adhesive for forming the second side wall portion 12b is printed on the glass plate 11a. Next, the 1st side wall part 12a is mounted. Next, an ultraviolet curable resin adhesive for forming the third sidewall portion 12c is printed on at least one of the first sidewall portion 12a and the glass plate 11b. Thereafter, the glass plate 11b and the first side wall portion 12a are overlapped, irradiated with ultraviolet rays in a pressurized state, and the adhesive is cured to cure the second and third side wall portions 12b and 12c. 12 can be completed.

  The side wall portion 12 is provided with a communication hole 17 that communicates with the internal space 18. The communication hole 17 is a liquid crystal injection hole used for injecting liquid crystal into the internal space 18. The communication hole 17 is sealed with a sealing material (not shown). The liquid crystal layer 16 is also provided at least on the inner space 18 side of the communication hole 17. The liquid crystal layer 16 may be provided on the entire communication hole 17.

  In the liquid crystal lens 1, the communication hole 17 is provided in each of the second side wall portion 12b and the third side wall portion 12c, but is not provided in the first side wall portion 12a. Thus, the communication hole may be provided in a part in the thickness direction of the side wall portion. Moreover, the communication hole may be provided in the whole in the thickness direction of a side wall part. The communication hole may be provided only in one of the second side wall and the third side wall.

  The cross-sectional shape of the communication hole 17 is not particularly limited. In the liquid crystal lens 1, the cross-sectional shape of the communication hole 17 is a rectangular shape.

  As shown in FIG. 2, the communication hole 17 is provided so that the center C of the internal space 18 is not located on an extension line of the central axis L <b> 1 of the communication hole 17 in plan view. That is, the straight line L3 passing through the connecting portion of the internal space 18 to the communication hole 17 and the center C of the internal space 18 and the central axis L1 of the communication hole 17 are not located on the same straight line but communicate so as to incline. A hole 17 is provided. In particular, in the liquid crystal lens 1, the communication hole 17 extends along the direction in which the tangent line L <b> 2 extends at the connection portion between the inner wall surface 12 d of the side wall portion 12 forming the internal space 18 and the communication hole 17 in plan view. Is preferably provided.

  By the way, the communication hole used as the liquid crystal injection hole is generally provided to be the shortest in consideration of the liquid crystal injection efficiency, the rigidity of the liquid crystal lens, and the like. Specifically, as shown in FIG. 3, the communication hole 117 is generally provided so as to extend along the radial direction of the internal space 118.

  However, as a result of intensive studies by the present inventors, it was found that when the communication hole 117 is provided so as to extend along the radial direction of the internal space 118, the wavefront aberration is increased. In addition, as a result of further earnest studies by the present inventors, the communication hole 17 so that the center C of the internal space 18 is not located on the extended line of the central axis L1 of the communication hole 17 in plan view as in the liquid crystal lens 1. It has been found that the wavefront aberration is reduced when. The reason for this is not clear, but may be as follows.

  In a liquid crystal lens, the orientation of liquid crystal molecules is considered to be affected by both the applied electric field and the orientation of liquid crystal molecules in the vicinity of the liquid crystal molecules. For this reason, if only the applied electric field is taken into consideration, the alignment directions of the liquid crystal molecules in the liquid crystal layer at the same distance from the optical axis should be equal, but in reality, they may be different.

  For example, a portion where liquid crystal molecules are not present on the outer side in the radial direction of the liquid crystal molecules located in a portion where the communication holes at the peripheral edge of the internal space are not provided, but a communication hole at the peripheral portion of the internal space is provided Many liquid crystal molecules exist outside the radial direction of the liquid crystal molecules located in the region. For this reason, the alignment of the liquid crystal molecules located in the portion of the inner space where the communication hole is not provided and the alignment of the liquid crystal molecules located in the portion of the inner space where the communication hole is provided are mutually Different. For this reason, if the distance from the optical axis to the edge of the liquid crystal layer varies in the circumferential direction, the alignment of the liquid crystal molecules at the periphery of the liquid crystal layer also varies. As a result, it is considered that the wavefront aberration is deteriorated. Therefore, as shown in FIG. 3, when the communication hole is provided so as to extend in the radial direction, the liquid crystal layer is divided into a portion where the communication hole is provided and a portion where the communication hole is not provided. Since the distance from the optical axis to the edge is greatly different, it is considered that the wavefront aberration increases.

  On the other hand, as shown in FIG. 2, in the liquid crystal lens 1, the communication hole 17 is provided so that the center C of the internal space 18 is not positioned on the extended line of the central axis L <b> 1 of the communication hole 17 in plan view. For this reason, variation in the distance from the center C to the edge of the liquid crystal layer 16 can be reduced. As a result, it is considered that the wavefront aberration is reduced.

  In particular, the communication hole 17 extends along the direction in which the tangent line L2 extends in the connection portion 19 between the inner wall surface 12d of the side wall portion 12 forming the internal space 18 and one side surface 17a of the communication hole 17 in plan view. In this case, that is, when the central axis L1 is parallel to the tangent L2, the variation in the distance from the center C to the edge of the liquid crystal layer 16 can be further reduced. As a result, it is considered that the wavefront aberration becomes smaller.

  Further, from the viewpoint of further reducing the variation in the distance from the center C to the edge of the liquid crystal layer 16, the width W of the communication hole 17 is preferably 1 mm or less, more preferably 500 μm or less, and 300 μm. More preferably, it is as follows.

  In the above embodiment, the example in which the liquid crystal lens has a plurality of liquid crystal layers has been described. However, the present invention is not limited to this configuration. In the present invention, the liquid crystal lens may have one liquid crystal layer.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal lens L1 ... Center axis L2 of a communicating hole ... Tangent L3 ... Straight line 9 ... Liquid crystal lens 10 ... Element main body 11a-11d ... Glass plate 12 ... Side wall part 12a ... 1st side wall part 12b ... 2nd side wall part 12c ... third side wall 16 ... liquid crystal layer 17 ... communication hole 18 ... internal space

Claims (2)

A pair of main walls disposed opposite to each other;
A side wall portion disposed between the pair of main wall portions and defining a cylindrical internal space together with the pair of main wall portions;
A liquid crystal layer disposed in the internal space;
With
In the side wall portion, a communication hole communicating with the internal space is formed,
The side wall in which the communication hole is provided so that the center of the internal space is not located on an extension line of the central axis of the communication hole in plan view , and the communication hole forms the internal space A liquid crystal lens provided so as to extend along a direction in which a tangent extends in a connection portion between the inner wall surface of the portion and one side surface of the communication hole . The liquid crystal lens according to claim 1, wherein the liquid crystal layer is also provided at least in a portion of the communication hole on the inner space side.

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