JPH02296222A - Liquid crystal lens - Google Patents

Abstract

PURPOSE:To allow the injection of a liquid crystal by a vacuum injection method and to improve spacing accuracy by providing a space to constitute a lens shape at the time of liquid crystal injection and a notch communicating with the outside to an annular spacer. CONSTITUTION:The liquid crystal lens 20 formed by sealing the liquid crystal into the space 24 constituting the lens shape formed between transparent substrates 21 and 22 disposed to face each other is provided with the notch 23a communicating the space 23 and the outside at the time of the liquid crystal injection on the inner periphery of the spacer 23. Namely, a communicating port communicating the spacer 24 and the outside of the lens is formed by the notch 23a provided on the spacer 23 when two sheets of the transparent substrates 21, 22 are disposed to face each other via the spacer 23. The injection of the liquid crystal into the space 24 by using the vacuum injection method is possible in this way. The spacer 23 is merely provided with the notch 23a in a part thereof and is not ruptured and, therefore, the spacer 23 does not deviate in the curvature direction of the transparent substrate surfaces even if pressing force is applied on the transparent substrates 21, 22 at the time of sticking these substrates to each other. The spacing accuracy is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal lens applicable to optical equipment such as cameras.

[Conventional technology]

Traditionally, adjusting the focal length of a lens was done by combining two or more lenses and changing their positional relationship, but recently, it has become possible to adjust the focal length of a lens by applying an external voltage to a single lens filled with liquid crystal. Liquid crystal lenses that change refractive power have been developed, and such liquid crystal lenses are disclosed in Japanese Patent Application Laid-open No. 5232348, Japanese Patent Application Publication No. 54-99654, Japanese Patent Publication No. 59-224820, and the like.

This type of liquid crystal lens is shown in FIG. 6(a). This liquid crystal lens 1 has a second transparent substrate on the side of the curvature of a first light-transmitting substrate 2 (hereinafter, a transparent substrate will be explained as an example of a light-transmitting substrate) having a concave curved surface. 3 is spacer 4
are arranged opposite to each other via the first. A liquid crystal layer 5 containing liquid crystal is formed in a space formed in the shape of a convex lens between the second transparent substrates. Further, transparent conductive layers 6 and 7 are formed on each opposing surface of the first and second transparent substrates 2.3. The transparent conductive layers 6 and 7 are connected to an AC voltage source 9 via lead wires. Voltage adjustment circuit] Voltage applying means consisting of 0 is connected. And, the configuration is such that a voltage is applied between the transparent conductive layers 6 and 7 by this voltage applying means. Note that FIG. 6(b) shows a plan view of the liquid crystal lens 1 viewed from the light incident side.

In the liquid crystal lens 1 configured as described above, the director of the liquid crystal molecules 5a is changed by changing the voltage applied to the liquid crystal layer 5 by the voltage applying means. As a result, the apparent refractive power of the liquid crystal changes for linearly polarized light in a specific direction. Therefore, as shown in FIG. 7, by using the liquid crystal lens 1 and the polarizing plate PL in combination, the refractive power of the liquid crystal lens 1 can be changed.

Here, in manufacturing the above-mentioned liquid crystal lens 1, first, a first transparent substrate 2 whose laminated joint portion is processed into a flat surface shape and a second transparent substrate 3 whose entire plate shape is formed, and a spacer 4 is placed between them. pasted together. Note that, like the first transparent substrate 2, a flat surface at the periphery of a concave curved surface can be processed relatively easily. In addition, as the spacer 4, similar to the liquid crystal display,
1st: An adhesive in which glass fiber pieces or resin balls are dispersed is used to bond the second transparent substrate together. Then, by the spacer 4, the first. A space having a convex lens shape having a predetermined thickness is formed between the second transparent substrates, and a liquid crystal layer 5 is formed by injecting liquid crystal into this space. In this way, the liquid crystal lens 1 is manufactured.

In addition, when manufacturing a liquid crystal lens 10 in which the bonding surface of transparent substrates is a curved surface, as shown in FIG. The second transparent substrate 12 and the second transparent substrate 12 are placed facing each other with a spacer 13 shown in FIG. Here, as the spacer 13, a material in which glass fiber pieces or resin balls are dispersed in an adhesive is used as described above. Generally, such a spacer 4.13 needs to be partially broken after the first transparent substrate 11 and the second transparent substrate 12 are bonded together in order to inject liquid crystal, for example, by a vacuum injection method. .

(Problem to be Solved by the Invention) By the way, when the bonding surface of the transparent substrate 11 is a curved surface as in the liquid crystal lens 10 shown in FIG. 8(a), the first transparent substrate 11 and the second When a pressing force is applied to bond the transparent substrate 12 with the spacer 13, the resin sphere 13a is displaced in the direction of arrow B along the curved surface of the first transparent substrate 1 around the cut point due to the pressing force. There was a high possibility that this would happen. As a result, the spacing accuracy of the spacer 13 deteriorates, making it impossible to make the thickness of the liquid crystal lens layer as designed. There were problems such as short-circuiting, and the focal length of the manufactured liquid crystal lens being different from the designed one. Furthermore, when the transparent substrates are attached to each other while being tilted to one side, the optical axis of the liquid crystal lens is shifted, causing a decrease in precision.

Although it is possible to solve the above problem by processing the periphery of the convex curved surface into a flat surface, such processing has been extremely difficult.

Further, Japanese Utility Model Application Publication No. 62-143927 discloses a ring-shaped film spacer. If such a ring-shaped film spacer is used, it is possible to suppress the occurrence of misalignment caused by pressing the transparent substrate, but since a liquid crystal injection port is not formed, vacuum injection, which is an effective method for liquid crystal injection, is not possible. The disadvantage is that the law cannot be used.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a liquid crystal lens that can improve spacing accuracy, has high precision, and can be manufactured easily.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention arranges two transparent substrates facing each other with a spacer interposed therebetween so that at least one of the facing surfaces becomes a curved surface. In a liquid crystal lens in which liquid crystal is sealed in a lens-shaped space formed between transparent substrates, the spacer has an annular outer shape, and the spacer has an annular outer shape, and the spacer has a ring shape on either the outer periphery or the inner periphery when the liquid crystal is injected. The structure includes a cutout that communicates the space forming the space with the outside.

(Function) By taking the above-mentioned measures, the present invention enables, when two transparent substrates are arranged facing each other with a spacer interposed therebetween, the cutout portion provided in the spacer allows the transparent substrates spaced apart by the spacer to A communication port is formed that communicates the space between the lens and the outside of the lens. Therefore, by using this communication port, liquid crystal can be injected into the space formed between the transparent substrates using a general vacuum injection method as a method for injecting liquid crystal.

Moreover, since the spacer is not completely broken with only a notch provided in a part, even if pressing force is applied in the opposing direction of both transparent substrates when bonding the two transparent substrates together, the spacer will not break completely. Scraping in the direction of curvature of the transparent substrate surface can be effectively prevented.

〔Example〕

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

FIG. 1 is a diagram showing the structure of a liquid crystal lens according to a first embodiment of the present invention. This liquid crystal lens 20 has a first transparent substrate 21 and a second transparent substrate 22 bonded together with a spacer 23 interposed therebetween. 1st. A lens-shaped space 24 is formed between the second transparent substrates 21 and 22, and liquid crystal is injected into this space 24. A space (liquid crystal N) 24 into which liquid crystal is injected is sealed with a sealant 25. The first transparent substrate 21 has a convex lens shape with a convex surface on the opposing surface side. A transparent conductive layer 26 is formed on the convex surface. In addition, the second transparent substrate 22
is in the form of a plate, with a polarizing film 27 on one side.
is provided, and the first transparent substrate 21 serving as the other surface
A transparent conductive layer 28 is formed on the opposite surface side. Note that an alignment film 29 is formed on each of the transparent conductive layers 26 and 28 formed on the first and second transparent substrates 21 and 22. Note that each transparent conductive layer 26 and 28 is provided with voltage application means (not shown) consisting of an alternating voltage source, a voltage adjustment circuit, etc.
is connected. The spacer 23 has a flat ring shape as shown in FIG.
is provided. Here, the spacer 23 is formed of a material having hardness and toughness to the extent that it does not bulge when pressed by the first and second transparent substrates 21 and 22. Further, the thickness of the spacer 23 depends on the size of the liquid crystal lens 20, and is generally designed so that the thickness of the liquid crystal layer (lens-shaped space) 24 is several hundred μm or less. Note that when the thickness of the spacer 23 is set to 100 μm or less, it is necessary to use a material with high toughness in consideration of workability during spacer processing and liquid crystal lens assembly. For this reason, the material of the spacer 23 is preferably plastic, ceramics, glass, metal whose surface is insulated, or the like.

Next, the operation of this embodiment will be explained.

When manufacturing a liquid crystal lens, when the first transparent substrate 21 and the second transparent substrate 22 are bonded together via the spacer 23, the first
The convex curved surface of the transparent substrate 21 is held by the inner peripheral edge of the annular spacer 23 to form a space 24 having a predetermined thickness. At this time, the notch 23a of the annular spacer 23 forms a communication port that communicates the inside of the space 24 with the outside of the lens. Therefore, liquid crystal can be injected through this communication port by, for example, a vacuum injection method, and a liquid crystal layer can be formed.

Therefore, according to the liquid crystal lens 20 according to this embodiment,
Since a notch 23a is provided in a part of the inner periphery of the annular spacer 23 to communicate the space 24 with the outside, liquid crystal can be injected under vacuum, and inconveniences such as the spacer being pushed out and displaced can be effectively prevented. Accuracy can be greatly improved.

As a result, the imaging characteristics and response recovery characteristics 2 of the liquid crystal lens 20
Properties such as light transmittance can be improved.

In addition, as a material for the spacer 23, the transparent substrate 21, 22
Since a material having appropriate hardness and toughness that can withstand the pressing force is used, spacing accuracy can be further improved.

In the first embodiment described above, since the facing surface of the first transparent substrate 21 had a convex curvature surface, the spacer 23 with the notch 23a provided on the inner periphery was used. In the case of a surface, an annular spacer with a notch formed on the outer periphery is used. That is, as shown in FIGS. 2(a) and (b),
A notch 31a is formed in a part of the outer periphery of the flat annular spacer 31 along the thickness direction of the spacer. The transparent substrate 32 and the plate-shaped second transparent substrate 22 are pasted together. Note that since the first transparent substrate 32 shown in the same figure has its outer circumferential portion processed into a planar shape, the notch 31a of the annular spacer 31 is located closer to the center of the first transparent substrate 32 than the bonding area with the first transparent substrate 32. The structure is such that a deep cut is made in the hole to form a communication port with the outside. In addition, Fig. 1(a)
Components having the same functions as those of the liquid crystal lens 20 shown in FIG.

With such a liquid crystal lens 3o, the same effects as in the first embodiment can be obtained.

FIG. 3 is a diagram showing the configuration of a second embodiment of the present invention. In this liquid crystal lens 4o, a first transparent substrate 42 and a second transparent substrate 43 are placed concentrically with each other via an annular spacer 44 within a lens frame 41 in which a cylindrical hollow with both ends open is formed. installed. The first transparent substrate 42 has a biconvex lens shape, and a transparent conductive layer 4 is provided on its surface.
5 is formed. Further, the second transparent substrate 43 has a single-convex lens shape, and the plane side is the same as the first transparent substrate 43.
is facing. A transparent conductive layer 46 is formed on the surface of this second transparent substrate 43, and an insulating film 47 is further formed on the transparent conductive layer 46 on the opposing surface side. Also,
A liquid crystal layer 48 is formed between the first transparent substrate 42 and the second transparent substrate 43, in which liquid crystal is sealed in a lens-shaped space formed by an annular spacer 44. Note that an alignment film 49 is formed on the transparent conductive layer 45 and the insulating layer 47 that are in direct contact with the liquid crystal layer 48 . The annular spacer 44 has a notch 44a formed in a part of its inner periphery, similar to that shown in FIG. 1(b). and lens frame 41
, the liquid crystal inlet 4 is located at the location where this notch 44a is located.
1a is provided. This liquid crystal injection port 41a is sealed with a sealant 51 after liquid crystal injection. Further, each transparent conductive layer 45, 46 has a voltage application terminal 525 at its peripheral edge.
3 are provided respectively. Voltage application means consisting of an alternating voltage source 54 and a voltage adjustment circuit 55 are connected to each of the terminals 52 and 53. Note that PL shown in the figure is a polarizing plate.

Next, a method for manufacturing the liquid crystal lens 40 having the above configuration will be described. First, the first transparent substrate 42 is produced by polishing both sides of optical glass into a convex shape.

Further, one surface is polished into a flat surface, and the other surface is polished into a convex shape to produce a second transparent substrate 43.

Then, transparent conductive layers 45 and 46 made of ITO (indium oxide/tin oxide) are formed on the surface of each transparent substrate 42 and 43. Furthermore, the transparent conductive layer 46 of the second transparent substrate 43
A SiO□ insulating film 29 is formed on the opposite side. Then, an alignment film 49 is formed by subjecting the area facing the liquid crystal layer 48 to rubbing alignment treatment with a nylon cloth.

Next, the first transparent substrate 42 and the second transparent substrate 43 are fitted with an annular spacer 44 in between, into a lens frame 41 obtained by cutting machinable ceramics into the shape shown in FIG.

Here, the annular spacer 44 is made of zirconia and has a flat plate shape with a notch 44a formed in a part of its inner periphery.
A piece having a thickness of 70 μm is prepared by polishing. The first transparent substrate 42 and the second transparent substrate 43 are separated by a spacer 4.
Once the transparent substrates 42 and 43 are bonded together through the lens frame 41, an adhesive 56 is applied to the boundary between the transparent substrates 42 and 43 and the lens frame 41, and the transparent substrates 42 and 43 are adhesively fixed to the lens frame 41.

In this state, the liquid crystal layer 48 is filled with the notch 44a of the annular spacer 44 and the liquid crystal injection port 41a of the lens frame 41.
A communication port is formed that communicates the space with the outside of the lens. Liquid crystal is injected into the space through this communication port using a vacuum injection method. When the liquid crystal injection is completed, open the liquid crystal injection port 41.
A, the liquid crystal layer 48 is sealed with a sealant 51. Voltage application terminals 52' and 53 are provided on opposite sides of the opposing surfaces of each transparent conductive layer 45, 46, respectively, and these terminals 52, 53
A voltage applying means is connected to. Then, the polarizing plate PL is attached to the lens frame 41.

When the characteristics of the liquid crystal lens 40 manufactured in this manner were investigated, it was possible to obtain response recovery speed and spacing accuracy that were almost equivalent to those of the liquid crystal lens 30 shown in the first embodiment. Further, the workability of the annular spacer 44 and the workability when assembling the liquid crystal lens 40 were extremely good. Furthermore, the spacer 44 could be manufactured without being damaged during processing, and could also be handled using a metal bottle set. Further, since the liquid crystal lens 40 is configured such that the transparent substrates 42 and 43 are fitted into the lens frame 41, the optical axis of the lens can be easily aligned.

Next, a third embodiment of the present invention will be described with reference to FIG. This example is an example of a liquid crystal lens that does not use a polarizing plate PL. This liquid crystal lens 60 has an auxiliary lens frame 62 inserted into a lens frame 61, and each lens frame 61.
A first transparent substrate 63 and a second transparent substrate 64 are arranged concentrically within the substrate 62 so that their optical axes coincide with each other. A plate-shaped transparent substrate 65 is inserted perpendicularly to the optical axis direction of the lens between the first transparent substrate and the second transparent substrate, and its outer periphery is connected to the auxiliary lens frame 62.
The insertion end of the lens frame 61 is brought into contact with a stepped portion within the lens frame 61.

An annular spacer 66 is interposed between the first transparent substrate 63 and a plate-shaped transparent substrate 65.
6, a liquid crystal layer 67 having a predetermined thickness is formed. Similarly, an annular spacer 68 is interposed between the second transparent substrate 64 and the plate-shaped transparent substrate 65, and a liquid crystal layer 69 is formed by this annular spacer 68. 1st
．． Second transparent substrate 63, 64 and plate-shaped transparent substrate 65
A transparent conductive layer 71 is formed on the surface. An insulating layer 7 is further formed on the surface of the transparent conductive layer formed on the transparent substrate 65.
2 is formed.

An alignment film 73 is formed in each region of the transparent conductive layer 71 and the insulating layer 72 that directly oppose the liquid crystal layers 67 and 69.

Further, each transparent conductive layer 71 is provided with a voltage application terminal, a lead wire is drawn out from each terminal, and an alternating voltage source 5
4. It is connected to voltage applying means consisting of a voltage adjustment circuit 55. The annular spacers 66, 68 have a similar shape to the spacer shown in FIG. 1(b). A liquid crystal injection port 61a is provided at a specific location of the lens frame 61°62 corresponding to the notch of the annular spacer 66,68. Liquid crystal is vacuum injected through the liquid crystal injection port 61a and the notches of the spacers 66 and 68.

Even with such a liquid crystal lens 60, the same effects as in the second embodiment can be obtained.

Next, an application example in which the liquid crystal lens shown in the above embodiment is applied to a CCD camera will be described with reference to FIG.

FIG. 5 is a diagram showing the configuration of a lens of a CCD camera.

In this application example, a liquid crystal lens 82 incorporated in a lens frame 81
is combined with a plurality of other lenses 83 to 85 which serve as master lenses to form one lens. Such a lens is attached to the CCD camera by a lens mount 86.

Also, the lens frame 81 to which the liquid crystal lens 82 is attached
The lithium battery 91. A liquid crystal lens drive circuit 92 is built in, and the refractive power of the liquid crystal lens 82 is changed by a switch 93.

When the lens thus constructed was attached to a CCD camera and the captured image was displayed on a monitor television, a good image could be obtained.

〔Effect of the invention〕

According to the present invention, two transparent substrates are arranged facing each other with a spacer interposed therebetween so that at least one of the facing surfaces is a curved surface, and a lens-shaped space is formed between the facing transparent substrates. In a liquid crystal lens in which liquid crystal is sealed, a notch is provided on either the outer periphery or the inner periphery of the annular spacer to communicate the lens-shaped space with the outside when the liquid crystal is injected. Liquid crystal can be injected by a vacuum injection method, and spacing accuracy can be improved. As a result, a liquid crystal lens with excellent characteristics such as imaging characteristics, response recovery characteristics, and light transmittance can be provided.

[Brief explanation of the drawing]

FIG. 1(a) is a block diagram of the first embodiment of the present invention, FIG.
b) is a plan view of an annular spacer, FIG. 2(a) is a configuration diagram of a liquid crystal lens whose facing surface is concave, FIG. 2(b) is a plan view of an annular spacer with a notch formed on the outer periphery, and FIG. 4 is a configuration diagram of a second embodiment of the present invention, FIG. 4 is a configuration diagram of a third embodiment of the present invention, and FIG. 5 is a configuration of an application example in which the liquid crystal lens according to the present invention is applied to a CCD camera lens. Figure, Figure 6(a)
6(b) is a plan view of the liquid crystal lens shown in FIG. 6(a), FIG. 7 is a diagram showing a combination of a polarizing plate and a liquid crystal lens, and FIG. 8 is a diagram showing a configuration of a conventional liquid crystal lens. Figure (a
) is a diagram of a conventional liquid crystal lens with a convex facing surface.
FIG. 8(b) is a diagram showing the structure of a conventional spacer. 20.30, 40.60...Liquid crystal lens, 21...
First transparent substrate, 22... Second transparent substrate, 23...
- Annular spacer, 23a...notch. Applicant's agent Patent attorney Atsushi Tsuboi (a) No. (a) No. (b) (b)

Claims (1)

[Claims] Two light-transmitting substrates are arranged facing each other with a spacer interposed therebetween so that at least one of the opposing surfaces is a curved surface, and a lens shape is formed between the light-transmitting substrates arranged oppositely. In a liquid crystal lens in which liquid crystal is sealed in a space forming a ring shape, the spacer is annular and has a notch on either the outer periphery or the inner periphery that communicates the space forming the lens shape with the outside when the liquid crystal is injected. A liquid crystal lens characterized by the following features: