JPS6138902A - optical element - Google Patents

Abstract

PURPOSE:To increase the change of a focal distance and to simplify the constitution of an optical element by forming an elastic body acting as a lens, an operation means coupled with the elastic body and a driving means for applying force to the operation means and deforming said elastic body. CONSTITUTION:The lens 6 is made of transparent elastic material and has two projected optical surfaces turned to the outside respectively. The operation member 5 may be adhered to the elastic body 6 with adhesives or a part of the member 5 may be embedded in the elastic body at the production of the elastic body. An outer cylinder 2 and a wire 4 are acted as a driving means, and when the outer cylinder 2 is moved, the elastic body 6 is pulled to the outside in the radius direction and deformed and its optical surface is displaced, so that a required optical characteristic, e.g. a focal distance, can be obtained. Thus, the change of the focal distance can be increased and the structure can be simplified.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to optical elements used in optical equipment such as cameras and videos, and electro-optic equipment such as optical communications and laser discs, and in particular, relates to optical elements used in optical equipment such as cameras and videos, and electro-optic equipment such as laser discs. The present invention relates to a variable focus optical element whose focal length can be changed by.

[Prior Art] Conventionally, as a variable focus lens, there is
No. 7, an elastic container filled with liquid and whose shape is changed by changing the liquid pressure, and JP-A-56
110403 and Japanese Unexamined Patent Publication No. 58-85415 using a piezoelectric material have been proposed.

However, the former so-called "liquid lens" requires a liquid reservoir, a pressurizing device, etc., and there is a problem in making the element compact. be.

[Object of the Invention] An object of the present invention is to solve the above-mentioned drawbacks, to provide a variable focus lens that has a large change in focal length and has a simple structure.

[Summary of the Invention] According to the invention, the above-mentioned object' consists of an elastic body acting as a lens, an operating means connected to this elastic body, and a force applied to this operating means, thus deforming said elastic body. This is achieved by an optical element including a drive means.

[Embodiments of the Invention] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, referring to Figure 1.2, the optical element shown here is:
An inner cylinder 1 and an outer cylinder 2 arranged outwardly from the inner cylinder.
The inner and outer cylinders are relatively movable in the direction of their longitudinal axes.

Four rollers 3 are rotatably attached to the top edge of the inner tube 1 at equal intervals in the circumferential direction, and each roller 3 receives a wire 4 having one end similarly attached to the top edge of the outer tube 2. ing. The opposite ends of the four wires 4 are respectively connected to corresponding operating members 5.

As best seen in FIG. 1, these operating members 5 are attached to the periphery of a lens 6 located approximately at the center of the upper opening of the inner cylinder 1 at equal intervals in the circumferential direction. This lens 6 is made of a transparent elastic material, as will be explained in more detail below, and has two outwardly convex back-to-back optical surfaces. This lens is often referred to herein as an elastic body.

In the above arrangement, for example, if the inner cylinder l is fixed and the outer cylinder 2 is moved downward, that is, in the direction shown by the arrow in FIG. ), the elastic body 6 is pulled radially outward and deformed, its optical surface is displaced, and the desired optical properties,
For example, you can get the focal length. It is obvious that the amount of change in focal length can be changed by changing the moving distance of the outer tube 2, that is, by changing the external force applied to the elastic body 6. The several stages of change of the lens, i.e. the elastic body 6, are shown in FIG.
The external force applied increases in the order of a) → (b) → (c).

Note that the operating member 5 may be bonded to the elastic body 6 with an adhesive, or the operating member 5 may be attached to the elastic body when manufacturing the elastic body.
You may embed part of it. Moreover, the number of operation members 5 is
It is selected as appropriate depending on the required shape of the optical surface and optical properties such as aberrations. For example, the convex optical surface shape can be made into a toric shape by attaching the operating member 5 to two locations sandwiching the center of the elastic body and pulling it in opposite directions. Furthermore, the driving means for pulling the elastic body outward in the radial direction is not limited to the configuration shown in FIG. The body 6 may also be deformed.

Next, referring to FIG. 4.5, the lens of the optical element shown here, that is, the elastic body 10, is similar to that shown in FIG. Part 1
1 are each made of a magnetic material, for example, a piece of iron.

Each operating member 11 has an extension portion 12 that projects outward,
This extension 12 has a correspondingly arranged drive device 13.
It's going inside.

Each drive device 13 has an opening 14 that opens toward the elastic body 10.
It consists of a yoke housing 15 having a yoke and a coil 16 disposed within this housing 15, and constitutes an electromagnet. The extension 12 of each operating member 11 projects into the respective housing 15 through an opening 14 . When an equal current is applied to these electromagnets, the operating member 11 is attracted by the electromagnets by an equal amount at the same time, and the elastic body 10 is therefore pulled radially outward by an equal amount at four points in the circumferential direction, and its optical The surface is displaced and the optical properties, ie the focal length, change.

Of course, by controlling the current flowing through the electromagnet, the force that pulls the elastic body 10 outward in the radial direction can be changed, and various deformations as shown in FIG. 3 can be performed. Note that the number of operating members 11 can be changed depending on the purpose as in the first embodiment, and the shapes and dimensions of the operating members and electromagnets are not limited to those shown in Fig. 4.5, and can be changed freely. It is Kabe.

FIG. 6.7 shows a third embodiment of the invention, in which the lens, i.e. the elastic body 20, is similar to that of the embodiment 1.2; Sandwiched between film-like second elastic bodies 21 and 22 made of transparent elastic material,
wrapped. Each second elastic body 21, 22 has a plurality of extensions 21A, 22A extending outward in the deformation direction, each of these extensions being connected to a corresponding extension of the other second elastic body, An external force can be applied to each of the connected extensions 21A, 22A as indicated by the arrows in FIG. As a driving means for applying this external force, the above-mentioned first method is used.
The drive means used in the second embodiment may be used, or a completely different type of drive means may be used.

The elastic body used in the present invention has the property of deforming when force is applied and returning to its original shape when the force is removed, as long as the applied force is not too large (within the elastic limit), that is, it has elasticity. use something

In a normal solid, the maximum strain (critical strain) within its elastic limit is about 1%. In addition, in vulcanized elastic rubber,
The elastic limit is extremely large, and the limit strain is 1000%.
Get closer.

In the optical element according to the present invention, an elastic modulus depending on the characteristics of the optical element to be formed is appropriately used, but in general, in order to easily obtain large elastic deformation, or to make the state after deformation optically more To ensure homogeneity,
It is preferable that the elastic modulus is small.

Note that the elastic modulus (G) is expressed as G=σ/γ (σ is stress, γ is elastic strain). Further, elasticity that causes large deformation with small stress is called high elasticity or rubber elasticity. Therefore, in the present invention, this type of elastic body can be particularly preferably used.

Such rubber elastic bodies include natural rubber, commonly known as "rubber", and e.g.

Styrene butadiene rubber (SBR), butadiene rubber (
BR), isoprene rubber (IR), ethylene propylene rubber (EPM, EPDM), butyl rubber (IIR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), urethane rubber (U), silicone rubber (Si), fluorine rubber (FPM), polysulfide rubber (T)
and synthetic rubbers such as polyether rubbers (FOR, CHR, CHC). All of these materials exhibit a rubbery state at room temperature; however, polymeric substances generally exhibit a glassy state or a glassy state depending on the degree of Brownian motion of the molecules.
It is either in a rubbery state or in a molten state. Therefore, polymeric substances exhibiting a rubbery state at the temperature at which optical elements are used can be widely used as uninvented elastic bodies. The elastic modulus in the rubber state is mainly determined by the crosslinking state of the polymer chains that make up the elastic body, and therefore, for example, vulcanization of natural rubber is nothing but a process that determines the elastic modulus.

In the present invention, it is desirable that the elastic body used be capable of large deformation with small stress, and therefore adjustment of the crosslinked state is important.

However, a decrease in the elastic modulus (a tendency for large deformations to occur with small stress) also leads to a decrease in strength. It is necessary to select the body appropriately. The elastic modulus is also measured by, for example, tensile, bending, or compression methods, depending on the type of stress depending on the usage of the optical element.

The elastic body used in the present invention has an elastic modulus of 101' to 1018 dyne/crn' smaller than that of a normal solid, and a rubber elastic body (7) 108 dyne/c,rn'
The following is suitable, preferably 106 dyne/c pi or less, particularly preferably 5 x 105 dyne/crn' or less, and the lower limit is when the elastic body constitutes an optical element,
Unlike normal liquids, the smaller the elastic material is, the better it will not spill. Note that although optical elements are often used at room temperature, they may also be used at particularly high or low temperatures, so the above range of elastic modulus is at the operating temperature of the optical element.

The hardness and softness of an elastic body depend to some extent on its elasticity.

JISK6301 stipulates a method of applying a minute strain to the surface of a sample using a spring and evaluating the hardness of rubber based on its penetration, which can be easily determined.

However, when the elastic modulus becomes a low value of 106 dyne/crn' or less, measurement cannot be performed using the above-mentioned method.

In that case, the penetration is evaluated using a 1/4-inch micro-consistency meter according to JIS K2808.

In addition, if the elastic modulus is small, it is difficult to measure it with "tension and elongation", so compression (5% deformation) is used.
The value can be determined by , and the correspondence with the penetration of the tip can be determined.

In addition to the conventionally known vulcanized (crosslinked) rubber elastic bodies, ethylene-vinyl acetate copolymers and A-B-Afi
Products that do not require vulcanization, such as butadiene-styrene block copolymers, and chain polymers, etc., can be obtained by gelling them to an appropriate (controlling the molecular chain length between crosslinking points!) I can do it.

In all of these, the elastic modulus is controlled by adjusting the crosslinking state, the combination of molecules in the block copolymer, the gel state, etc.

Further, in addition to controlling the elastic body depending on the structure of the elastic body itself, its properties can be changed and adjusted by adding a diluent or a filler.

For example, silicone rubber (product name of Shin-Etsu Chemical Industry Department:
KE104) and catalyst (product name of Shin-Etsu Chemical Industry Department: CAT
-104) and a diluent (product name of Shin-Etsu Chemical Co., Ltd.: RT
When V-thinner) is added, as the amount added increases, the hardness and tensile strength decrease, and conversely, the elongation increases.

[Effects of the Invention] According to the present invention, by pulling the elastic body outward in the radial direction, the optical surface of the elastic body is displaced and a desired optical characteristic, for example, a focal length can be obtained. Therefore, simply by applying an external force to the elastic body, the optical surface changes reversibly to obtain the desired optical characteristics, making it extremely easy to configure and control optical elements, and making it possible to easily change the shape of the optical surface. Due to the change in the underlying optical properties, the rate of change in the optical properties can be set extremely large.

[Brief explanation of drawings]

FIG. 1 is a plan view of an optical element according to the invention. FIG. 2 is a sectional view taken along line II in FIG. 1. FIG. 3 is a diagram showing a deformed state of the elastic body according to the present invention. FIG. 4 is a plan view showing another embodiment of the optical element according to the present invention. FIG. 5 is a sectional view taken along line IV-IV in FIG. 4. FIG. 6 is a plan view showing another embodiment of the optical element according to the present invention. FIG. 7 is a sectional view taken along line VI-VI in FIG. 6. 1...inner cylinder, 2 fists...outer cylinder, 3 fists...roller, 4...
・Wire, 5... Operating member, 6... Elastic body, 10...
...elastic body, 11.. operation member, 12.. extension part,
13...Driving electromagnet, 20-fist/elastic body, 21.2
2◆...Second elastic body. O Figure 2 Figure 3 (a) (b) (c)
4th) 1st Figure 5

Claims (4)

[Claims] (1) An optical element characterized by including an elastic body that acts as a lens, an operating means connected to the elastic body, and a driving means that applies force to the operating means and thus deforms the elastic body. . (2) The operation means includes a plurality of operation members coupled to the periphery of the elastic body, and the drive means includes wires connected to each of the operation members and a drive device that pulls these wires. An optical element according to claim 1. (3) An electromagnetic device in which the operating means includes a plurality of operating members made of a magnetic material coupled to the periphery of the elastic body, and the driving means applies magnetic force to these operating members to deform the elastic body. The optical element according to claim 1, comprising: (4) The operating means is made of a transparent film-like second elastic body similar to the elastic body that acts as the lens, and the second elastic body sandwiches and wraps the elastic body that acts as the lens, 2. The optical element according to claim 1, wherein the driving means deforms the elastic body acting as the lens by pulling the second elastic body.