JP2009294654A - Spectacles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide spectacles never seen before, having multi-focal point or continuously varying the focal point using the technology of a liquid crystal lens. <P>SOLUTION: The spectacles include a frame. Inside the frame, a lens group is provided. The lens group includes a liquid crystal lens and a concave lens 150 with a negative power. The liquid crystal lens is adapted to vary the power from 0 toward the positive by controlling the voltage application of a power supply circuit. The power supply circuit is controlled by a control circuit. The spectacles include a ranging mechanism for measuring a distance to an object observed at that time by a user. The control circuit controls the power supply circuit according to the distance to the object measured by the ranging mechanism, and the power supply circuit changes a potential difference applied to the liquid crystal lens. The resultant power of the lens group ranges from the positive to the negative. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to spectacles using a variable focus lens having a variable focus, such as a liquid crystal lens.

One of the application fields of liquid crystal applied to various fields is a lens. The lens, called a liquid crystal lens, utilizes the property of liquid crystal that the refractive index changes depending on the orientation state. By controlling the liquid crystal layer arranged perpendicular to the light transmission direction so that the alignment state is different for each portion in the direction perpendicular to the light transmission direction, for example, a liquid crystal of uniform thickness Even so, it can have a lens-like property.
Such a liquid crystal lens has a great feature that the property of the lens (for example, focal length) can be changed, or the property as a lens can be given or lost by changing the alignment state of the liquid crystal. . That is, the liquid crystal lens functions as a variable focus lens.
This feature is different from a classic lens made by giving a convex or concave shape to transparent glass or resin and fixing its properties, and its commercialization is desired.

A conventional liquid crystal lens is configured as follows, for example.
Among conventional liquid crystal lenses, a certain type includes two transparent plates arranged in parallel and a voltage between them provided along the two plates (for example, inside the plate). And a liquid crystal layer filled between two plates. In general, the two plates are both rectangular. Both of the two transparent electrodes are generally the same size and shape as the two plates, but at least one of them is often provided with a circular opening. When such a transparent electrode is used, if a predetermined potential difference is applied between the two transparent electrodes, the electric field generated at the center of the transparent electrode opening becomes the weakest and the electric field generated at the edge of the transparent electrode opening is the strongest. Therefore, the strength of the electric field is generated from the center of the opening of the transparent electrode to the outside. Based on the distribution of the electric field, the liquid crystal in the liquid crystal layer filled between the two plates changes the alignment state depending on the part, and thus the above-described liquid crystal lens has a function as a lens.

Such a liquid crystal lens has been expected to be applied to perspective glasses for a long time. Bifocal glasses require two focal points for near and far viewing, and generally the former is placed on the lower half of the eyeglass lens and the latter on the upper half of the eyeglass lens. . Due to the structure of such bifocal glasses, the field of view is about half that of normal glasses, whether near or far.
However, if the liquid crystal lens as described above is used, such a problem is eliminated.
As a result of promoting such a concept, the applicant of the present application, using the liquid crystal lens as described above, is different from the conventional bifocal glasses, the multifocal or non-conventional glasses capable of continuously changing the focus. I realized that I could do it.

  Further, in addition to the liquid crystal lens, the applicant of the present invention may use a liquid crystal of the liquid crystal lens for a predetermined substance (for example, an electro-optic crystal, for example, KTN (tantalum), which changes its refractive index depending on the site according to the electric field distribution. By replacing with potassium niobate, KTa1-xNbxO3), it is possible to obtain a more general variable focus lens, and even if such a variable focus lens is used, I realized that I could not realize the glasses as mentioned above.

JP2005-92009 JP 2006-313248 A

Liquid crystal molecular alignment effect and its application to new optical devices (Akita University Department of Electrical and Electronic Engineering Susumu Sato / 2006 Japanese Liquid Crystal Society discussion)

  The present invention provides non-conventional glasses that are different from conventional bifocal glasses and that have multifocal or continuously changing focus by using a technique of a variable focus lens such as a liquid crystal lens. Objective.

In order to solve the above-mentioned problems, the present inventor proposes the following glasses.
The glasses include a liquid crystal lens and fixing means configured like glasses for fixing the liquid crystal lens in front of the user's eyes.
The liquid crystal lens of the glasses includes two transparent plates arranged at a predetermined interval, two transparent electrodes provided in pairs with the plates along the two plates, A liquid crystal layer disposed between the two transparent electrodes, voltage applying means for applying a desired voltage between the two transparent electrodes, and when a voltage is applied between the two transparent electrodes. A refractive index distribution is generated in the liquid crystal layer. The eyeglasses further include distance measuring means for measuring a distance to an object estimated to be viewed by a user when wearing the eyeglasses, and the voltage applying means is the distance measuring means. The voltage applied between the two transparent electrodes is controlled based on the distance to the object measured in (1).
The glasses are configured such that the focal point of the liquid crystal lens can be changed based on the distance to the object estimated by the user as measured by the distance measuring means.
Such glasses can be focused on multiple focal points, or the focal point can be changed continuously, and the field of view can be narrowed like conventional perspective glasses. It will not be. Such glasses may be useful for those other than those suffering from myopia and hyperopia, and its application is expected.

The above-described invention can be more generalized by replacing the liquid crystal lens of the invention with a variable focus lens. That is, in the above-described glasses, the liquid crystal layer that the glasses have is arranged between two transparent electrodes, in which a refractive index distribution is generated when a voltage is applied between the two transparent electrodes. It is possible to replace the layer with a predetermined substance.
In such a case, the spectacles described above are spectacles including a variable focus lens, and fixing means configured like glasses for fixing the variable focus lens in front of the user's eyes, The variable focus lens includes two transparent plates arranged at a predetermined interval, two transparent electrodes provided in pairs with each of the plates along the two plates, and the two transparent electrodes. And a voltage applying means for applying a desired voltage between the two transparent electrodes. When a voltage is applied between the two transparent electrodes, a refractive index is applied to the layer. A distribution means is provided, and comprises a distance measuring means for measuring a distance to an object estimated to be viewed by a user when wearing the glasses, and the voltage applying means comprises: Based on the distance to the object measured by the distance measuring means , And controls the voltage to be applied between the two transparent electrodes, the glasses.

The present invention described above can have the following variations.
In the following description, the description will be made on the assumption that the variable focus lens is a liquid crystal lens in order to make the description concrete, but the liquid crystal of the liquid crystal lens is replaced with the “predetermined substance” as described above. It is possible for those skilled in the art to understand that an invention having a variable focus lens having such a “predetermined substance” instead of a liquid crystal lens is also disclosed in the following description. I will.

In the eyeglasses of the present invention, as described above, the focal point of the liquid crystal lens changes depending on how to apply a voltage between the two transparent electrodes. In this case, the focal point of the liquid crystal lens may be multifocal or continuously changing as described above.
Further, the liquid crystal lens of the spectacles of the present invention may change its power from a predetermined value of 0 to + or from a predetermined value of − to 0. The power may be changed from negative power to negative power. However, this cannot be realized with a liquid crystal lens alone. The liquid crystal lens can change the focal point (change the power of the lens), but when no potential difference is given between the transparent electrodes, no alignment occurs in the liquid crystal, and a potential difference is given between the transparent electrodes. In view of the fact that the orientation of the liquid crystal occurs when the liquid crystal is aligned, and the state of alignment of the liquid crystal that occurs when a potential difference is applied between the transparent electrodes is the same regardless of the direction of applying the potential difference, the liquid crystal lens The power possessed is from 0 to + predetermined value, or from a predetermined value of -0 to 0, and does not cross 0. However, when the spectacles are bifocal spectacles, the power of the liquid crystal lens needs to cross over zero. The present invention solves this by using the following lens.
For example, the eyeglasses of the present invention include a lens having positive power and placed on the same optical axis as the liquid crystal lens. In this case, in the liquid crystal lens, the refractive index distribution generated in the liquid crystal layer when the voltage applying unit applies a voltage between the two transparent electrodes is such that the power of the liquid crystal lens including the liquid crystal layer is the power of the liquid crystal lens. The negative power more than canceling the positive power of the lens is generated, or the glasses of the present invention have a negative power and are placed on the same optical axis as the liquid crystal lens. Equipped with a lens. In this case, in the liquid crystal lens, the refractive index distribution generated in the liquid crystal layer when the voltage applying unit applies a voltage between the two transparent electrodes is such that the power of the liquid crystal lens including the liquid crystal layer is the power of the liquid crystal lens. It is something that produces positive power that cancels out the negative power of the lens. These glasses can be used as bifocal glasses because the combined power of the lens and the liquid crystal lens ranges from plus to minus across 0.

In the liquid crystal lens of the present invention, when the voltage application means applies a voltage between the two transparent electrodes, a refractive index distribution is generated in the liquid crystal layer.
Any mechanism for generating a refractive index distribution in the liquid crystal layer may be used. For example, one of the transparent electrodes may have a hole as described in the background art section. Become.
As another example, the liquid crystal lens includes a dielectric constant distribution forming means for providing a dielectric constant distribution in a plane direction of the two transparent electrodes in a space between the two transparent electrodes. Can be mentioned.
In the case of the liquid crystal lens introduced in the background art that provides an opening in at least one of the transparent electrodes, the liquid crystal layer located inside the opening does not have a transparent electrode that gives a potential difference in the vicinity thereof (the opening in the liquid crystal layer). The portion located inside is not sandwiched between the transparent electrodes from both sides.) When the aperture is large, it is difficult to maintain the desired electric field gradient from the edge of the aperture to the center of the aperture. . If the potential difference created between the two transparent electrodes is increased, the gradient of the electric field may be maintained within a preferable range. However, the larger the opening, the larger the potential difference to be applied between the transparent electrodes. When the potential difference applied between the transparent electrodes is increased, a power source for generating a high voltage is required, which is difficult in terms of cost and somewhat difficult in terms of safety. In other words, the conventional liquid crystal lens has strong limitations on the shape and size, and has a problem that it is difficult to drive the liquid crystal lens with a low voltage for the area of the liquid crystal lens.
In the liquid crystal lens provided with the dielectric constant distribution forming means as described above, if a potential difference is formed between the two transparent electrodes even if there is no opening in either of the two transparent electrodes, The electric field generated between the transparent plates can be changed depending on the location of the plates, whereby the alignment state of the liquid crystal can be changed depending on the location of the liquid crystal layer. Such a liquid crystal lens does not require a hole in the transparent electrode as in the prior art, and the distance between the transparent electrodes can be kept small in the entire range of both transparent electrodes. Since it is suitable for reducing the potential difference, it is convenient for use with the glasses of the present invention.

The plate used in the liquid crystal lens of the present invention may be a flat plate, but is not necessarily a flat plate. For example, the plate may be curved. Further, at least one surface of the plate used in the liquid crystal lens of the present invention may be uneven. The two plates are arranged substantially in parallel, but may not be completely parallel. If the two plates are both flat, have no irregularities, and are completely parallel to each other, the liquid crystal lens can be made thin.
The lens in the spectacles of the present invention may be integrated with one of the liquid crystal lens plates. For example, when one of the plates includes a dome-shaped portion that bulges outward, the dome-shaped portion becomes the lens of the present invention.

The dielectric constant distribution formed by the dielectric constant distribution forming means in the present invention may be appropriately selected according to the purpose that the liquid crystal lens should have. The change in the dielectric constant may be designed in consideration of, for example, the shape of the plate (the plate itself may function as a lens depending on the shape), the lens combined with the liquid crystal lens, and other optical systems. .
For example, the dielectric constant distribution given by the dielectric constant distribution forming means according to the present invention is such that, for example, when a voltage is applied to the two transparent electrodes, the refractive index of light when vertically incident on the two plates is light It may be configured to gradually increase or decrease about the axis. This makes it easy to combine the liquid crystal lens with a lens having a refractive index that gradually increases or decreases with the optical axis as the center. In this case, the dielectric constant distribution given by the dielectric constant distribution forming unit may be a concentric circular distribution.

The dielectric constant distribution forming means in the present invention is not particularly limited as long as it can form a dielectric constant distribution. For example, the dielectric constant distribution forming means may be formed by a distribution of a concentration of dielectric powder whose particle size does not affect the transparency of the liquid crystal lens.
The dielectric may be any material, for example, barium titanate.
The particle size of the dielectric may be a level that does not affect the transparency of the liquid crystal lens (in many cases, the transparency to visible light). For example, the diameter may be on the order of μm or less. It is done.
The dielectric constant distribution forming means may be layered. The term “layered” in this case includes not only a continuous layer as a whole but also a discontinuous layer as a whole. A discontinuous layer as a whole is, for example, a case where a part of the layer has a gap or a layer that is scattered.

In the present invention, the dielectric constant distribution forming means described above may be provided in a space sandwiched between two transparent electrodes as described above. In the present application, the phrase “in a space sandwiched between two transparent electrodes” includes not only a space sandwiched between two transparent electrodes but also a surface of the two transparent electrodes facing the space.
In the present invention, the two transparent electrodes in the liquid crystal lens are paired with each of the two plates. That is, the present invention has two pairs of plates and transparent electrodes. Both of these two pairs of plates and transparent electrodes may be in a positional relationship where the inner transparent electrode is on the outer side or vice versa (in this application, the term “outer” , Meaning the side far from the center of the thickness direction of the liquid crystal layer). There is no need for the positional relationship (internal / external positional relationship) between the transparent electrode and the plate to be the same in both of the two pairs of plates and the transparent electrode.
The transparent electrode is provided along the plate, but is not necessarily in close contact with the plate. Other members may exist between the transparent electrode and the plate.

Although it depends on the positional relationship between the paired plates and the transparent electrode, the change in the dielectric constant in the present invention can be provided at the locations exemplified below.
When the transparent electrode paired with the plate is provided outside the plate included in a pair of the two pairs of the plate and the transparent electrode, the dielectric constant distribution forming means It may be provided on the inner surface.
When the transparent electrode paired with the plate is provided outside the plate included in a pair of the two pairs of the plate and the transparent electrode, the dielectric constant distribution forming unit includes the transparent electrode and the transparent electrode. It may be provided on the paired plates. In this case, the dielectric constant distribution forming means may be provided in any part (for example, the inside) of the plate included in a pair of the two pairs of the plate and the transparent electrode. And at least one surface of the plate included in a pair of the transparent electrodes.
When the transparent electrode paired with the plate is provided outside the plate included in a pair of the two pairs of the plate and the transparent electrode, the dielectric constant distribution forming means Even if it is provided on a transparent transparent layer provided inside (for example, between the transparent electrode and the plate paired with the transparent electrode or inside the plate paired with the transparent electrode) Good. When there is a transparent layer, the dielectric constant distribution forming means may be provided in any part of the transparent layer (for example, the inside thereof), but the dielectric constant distribution forming means is provided on at least one surface of the transparent layer. It may be done.
When the transparent electrode paired with the plate is provided inside the plate included in a pair of the two pairs of the plate and the transparent electrode, the dielectric constant distribution forming means It may be provided on the inner surface of the electrode.
When the transparent electrode paired with the plate is provided inside the plate included in a pair of the two pairs of the plate and the transparent electrode, the dielectric constant distribution forming means You may be provided in the transparent transparent layer provided inside the electrode. When there is a transparent layer, the change in dielectric constant may be provided in any part of the transparent layer (for example, the inside), but the dielectric constant distribution forming means is provided on at least one surface of the transparent layer. May be.
The change in dielectric constant may be provided in both a pair of two plates and a transparent electrode (and a transparent layer in some cases).
When the dielectric constant distribution forming means is provided on the inner surface of the transparent electrode, the dielectric constant distribution forming means is arranged on the inner surface of the transparent electrode such that the particle size does not affect the transparency of the liquid crystal lens. By providing a distribution of the concentration of the dielectric powder, a dielectric constant distribution can be formed.
In the case where the dielectric constant distribution forming means is provided on the surface of the plate, the dielectric constant distribution forming means has a particle size on at least one surface of the plate so that the particle size does not affect the transparency of the liquid crystal lens. By providing a distribution of the concentration of the dielectric powder, a dielectric constant distribution can be formed.
When the dielectric constant distribution forming means is provided on the surface of the transparent layer, the dielectric constant distribution forming means has a particle size on at least one surface of the transparent layer so that the particle size does not affect the transparency of the liquid crystal lens. By providing a distribution of the concentration of the dielectric powder, a dielectric constant distribution can be formed.
When distributing dielectric powder on the surface of a predetermined object such as a plate, transparent electrode, transparent layer, etc., printing is performed using an ink-like material in which dielectric powder is mixed in some binder. A distribution of the concentration of the dielectric powder can be created on the surface of a given object. Since the printing technology is highly completed, there is no great difficulty in creating a concentration distribution of dielectric powder on the surface of a plate, transparent electrode, transparent layer or the like.

As the distance measuring means used in the glasses of the present invention, for example, those used for realizing an AF (Auto Focus) function widely used in digital cameras can be applied. The parameter measured by the distance measuring means does not necessarily need to be the distance to the object, and the distance measuring means can calculate the distance to the object indirectly by calculating other measured parameters. It does not matter. In some AF mechanisms, in addition to measuring the distance to the object, some AF functions are realized based on the sharpness of the edge of the object reflected in the image sensor such as a CCD. What measures the distance to an object indirectly using such a principle is also contained in the ranging means of this application.
The spectacles may include a determination unit that determines whether the distance to the object is larger or smaller than a reference distance that is a predetermined distance. In this case, the voltage application unit is configured such that when the determination unit determines that the distance to the object is greater than the reference distance, the power after the combination of the liquid crystal lens and the lens becomes negative. In addition, when the determination unit determines that the distance to the object is smaller than the reference distance, the two transparent electrodes are set so that the combined power of the liquid crystal lens and the lens is positive. The voltage applied during the period may be controlled. Such a configuration is useful for easily realizing automatic switching of the focus of the glasses by control using the reference distance as a threshold.
The distance measuring unit may measure a distance to the object by using an object in the front direction of the user's face as the object. Such a configuration is useful for making it possible to easily measure the distance to an object without detecting the user's line of sight.

The perspective view which shows the structure of the liquid crystal lens by embodiment. FIG. 2 is a plan view conceptually showing one surface of a transparent electrode of the liquid crystal lens shown in FIG. 1. The perspective view which shows the structure of the liquid crystal lens by the modification 1. FIG. The perspective view which shows the structure of the liquid crystal lens by the modification 2. FIG. FIG. 10 is a perspective view illustrating a configuration of a liquid crystal lens according to Modification 3. The perspective view which shows the structure of the liquid crystal lens by the modification 4. FIG. The perspective view which shows the structure of the both-sides spectacles. The longitudinal cross-sectional view which shows the structure of the lens group in the spectacles for both distances shown in FIG. FIG. 8 is a longitudinal sectional view showing another configuration of a lens group in the bifocal glasses shown in FIG. 7.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

≪Liquid crystal lens≫
First, the configuration of the liquid crystal lens used in this embodiment will be described.
A schematic configuration of the liquid crystal lens 100A is shown in FIG.
The liquid crystal lens 100A has two transparent plates 10. The transparent plate 10 of this embodiment is not necessarily limited to this, but is a flat plate having a uniform thickness. In this embodiment, these plates 10 are made of glass, but may be made of resin such as acrylic. In this embodiment, the two transparent plates 10 have the same rectangular shape and are parallel to each other.
A transparent electrode 20 is provided inside each of the two transparent plates 10. The transparent electrode 20 may be a known one, and is formed using ITO (indium tin oxide), zinc oxide, tin oxide or the like as a material. The transparent electrode 20 is a well-known method such as a sputtering method, a vacuum deposition method, a sol-gel method, a cluster beam deposition method, or a PLD method. In this embodiment, the transparent electrode 20 is provided in close contact with the inner surface of the plate 10. Yes.
A liquid crystal layer 30 is provided between the two plates 10. In this embodiment, the liquid crystal layer 30 is provided between the two plates 10 via the transparent electrode 20. Although not necessarily limited to this, in this embodiment, the liquid crystal layer 30 has a higher degree of electric field in the portion where the liquid crystal layer 30 is located, and the degree of alignment of the liquid crystal in that portion increases and the refractive index decreases. It is supposed to be. The liquid crystal used in this embodiment is a thermotropic liquid crystal, and more specifically, a nematic liquid crystal having a positive dielectric anisotropy.
However, despite the name, the liquid crystal layer 30 does not necessarily have to be composed of liquid crystals, and when a voltage is applied between the two transparent electrodes 20, a refractive index distribution corresponding to the electric field is generated. What is necessary is just to be comprised with the predetermined substance with a property. An example of a layer made of such a material is a liquid crystal layer made of liquid crystal, and another example is an electrical engineering made of an electro-optic crystal, eg KTN (potassium niobate tantalate, KTa1-xNbxO3) It is a crystal layer.
The transparent electrode 20 is connected to an external power circuit 40 with a cable 41. The power supply circuit 40 can apply a desired potential difference between the two transparent electrodes 20.

In this embodiment, since both the transparent electrodes 20 are inside the plate 10, a device for changing the dielectric constant is provided on the inner surface of the transparent electrode 20.
The device is as follows.
In this embodiment, the dielectric powder is formed on the inner surface of one of the two transparent electrodes 20 so as to have a concentric concentration distribution centered on the center of the transparent electrode 20 when viewed in plan. It is attached.
As the dielectric, for example, a known material such as Rochele salt (abbreviation: R salt), potassium dihydrogen phosphate (abbreviation: KDP), and potassium arsenate which is a similar substance of KDP can be used. In this case, barium titanate (abbreviation: BT), which is more widely used, is used.
The particle size of the dielectric powder only needs to be small enough not to affect the transparency of the liquid crystal lens 100A (in this embodiment, the transparency to visible light), but in this embodiment, the particle size is set to the order of μm or less. More specifically, the order is nm. That is, the dielectric powder in this embodiment is so-called nanoparticles.
The dielectric material is attached to the transparent electrode 20 by printing a dispersion containing a binder such as polyvinyl alcohol and a dielectric powder on the inner surface of the transparent electrode 20 using an inkjet printing apparatus. Can do.
FIG. 2 conceptually shows the state of the surface of the transparent electrode 20 on which the dielectric is printed. Dielectric printing is performed in a range surrounded by a circle indicated by a broken line in FIG. The center of the circle coincides with the center of the transparent electrode 20 as described above. In this embodiment, the concentration of the dielectric at the center of the circle is substantially zero. The density of the transparent electrode 20 at the edge of the circle is determined according to the magnitude of the refractive index to be generated in this portion. In this embodiment, the concentration of the dielectric gradually increases smoothly from the center of the circle toward the outside when viewed in the radial direction of the circle.
The binder containing the dielectric powder is not necessarily limited to this, but in this embodiment, the binder is layered. The binder containing the dielectric powder may be a continuous layer or a discontinuous layer. In this embodiment, the binder is a discontinuous layer by ink jet printing.
In this embodiment, the concentration distribution of the dielectric provided on the inner surface of one of the two transparent electrodes 20 is such that the concentration gradually increases from the inside toward the outside around a predetermined point. Concentric distribution is used, but conversely, concentric distribution in which the concentration gradually decreases from the inside to the center with a predetermined point as the center is also possible.
In this embodiment, the concentration distribution of the dielectric powder as described above is formed on the inner surface of one of the two transparent electrodes 20. A concentration distribution of the dielectric powder as described above may be formed on the surface. However, when the above-described concentration distribution due to the dielectric powder is formed on the inner surfaces of the two transparent electrodes 20, the concentration distribution due to the dielectric powder formed on the inner surface of the transparent electrode 20 can be reduced. Aspects need not necessarily be the same.

The liquid crystal lens 100A of this embodiment operates as follows.
First, when there is no potential difference between the two transparent electrodes 20 included in the liquid crystal lens 100A (when the power supply circuit 40 does not apply a potential difference between the two transparent electrodes 20), the liquid crystal lens of this embodiment is used. 100A does not function as a lens, and its focal length is basically infinite. However, the liquid crystal lens 100A has a different dielectric constant depending on the width direction part thereof due to the above-described concentration distribution of the dielectric powder, and therefore, the refractive index may differ depending on the width direction part based on the dielectric constant. In this case, the liquid crystal lens 100A functions as a lens based on the refractive index distribution corresponding to the density distribution of the dielectric powder, but the focal length is considerably long even in consideration thereof.
When the above-described power supply circuit 40 gives a potential difference between the two transparent electrodes 20, the liquid crystal lens 100A functions as a lens. When the power supply circuit 40 gives a potential difference between the two transparent electrodes 20, an electric field is generated between the two transparent electrodes 20, and this electric field is generated by the above-described circle provided inside one transparent electrode 20. According to the concentration distribution of the dielectric powder, which is lowered as it is closer to the center (center of the transparent electrode 20), it is weaker as it is closer to the center of the circle (center of the transparent electrode 20) and becomes stronger as it is farther from the center of the circle. However, the electric field outside the circle is uniform. Therefore, the degree of orientation of the liquid crystal layer 30 when a potential difference is applied between the two transparent electrodes 20 increases as the distance from the center of the transparent electrode 20 increases, and the refractive index due to the liquid crystal increases as the distance from the center of the transparent electrode 20 increases. Become. This means that the liquid crystal lens 100A (more precisely, the portion corresponding to the above-mentioned circle in the liquid crystal lens 100A) functions in the same way as a convex lens having positive power. When the potential difference given by the power supply circuit 40 between the two transparent electrodes 20 is increased, the degree of alignment of the liquid crystal in the liquid crystal layer 30 is increased as a whole, so that the two transparent layers until the potential difference reaches a certain threshold value. The greater the potential difference provided between the electrodes 20, the greater the power of the liquid crystal lens 100A.
Note that when the concentration distribution of the dielectric is increased as it is closer to the center, the refractive index distribution when the potential difference is applied between the two transparent electrodes 20 is smaller as the position is closer to the center of the transparent electrode 20. This means that such a liquid crystal lens 100A functions similarly to a concave lens having negative power. In this case, when the potential difference given by the power supply circuit 40 between the two transparent electrodes 20 increases, the power of the liquid crystal lens 100A decreases accordingly.

<Modification 1>
A liquid crystal lens 100B according to Modification 1 will be described.
A liquid crystal lens 100B according to Modification 1 basically has the same configuration as the liquid crystal lens 100A according to the embodiment.
As shown in FIG. 3, the liquid crystal lens 100 </ b> B according to Modification 1 includes two plates 10, two transparent electrodes 20, and a liquid crystal layer 30 from the outside, as in the case of the liquid crystal lens 100 </ b> A according to the embodiment. A power supply circuit 40 connected to the two transparent electrodes 20 is provided. The functions of the plate 10, the transparent electrode 20, and the liquid crystal layer 30 of the liquid crystal lens 100 </ b> B of Modification 1 are the same as those in the embodiment.
The liquid crystal lens 100B of the modification 1 is different from the liquid crystal lens 100A according to the embodiment. The liquid crystal lens 100B of the modification 1 includes the transparent layer 50 and the liquid crystal that are not included in the liquid crystal lens 100A according to the embodiment. The difference is that two layers are provided between the layers 30. The transparent layer 50 is a transparent layer. In the first modification, the transparent layer 50 is made of a resin formed into a thin film. The type of resin that constitutes the transparent layer 50 is not particularly limited. In Modification 1, at least one of the two transparent layers 50 is provided with a concentration distribution as shown in FIG. 2 using dielectric powder. Such a concentration distribution is not necessarily limited to this, but in Modification 1, it is provided on at least one side of at least one of the two transparent layers 50. The method for forming the concentration distribution by the dielectric in the transparent layer 50 may be the same printing as in the embodiment.
In the case where a dielectric concentration distribution is not formed in both of the two transparent layers 50, the transparent layer 50 may be a single layer.

<Modification 2>
A liquid crystal lens 100C according to Modification 2 will be described.
The liquid crystal lens 100C according to the modification 2 basically has the same configuration as the liquid crystal lens 100A according to the embodiment.
As shown in FIG. 4, the liquid crystal lens 100 </ b> C according to the modified example 2 includes the same two plates 10, two transparent electrodes 20, a liquid crystal layer 30, and two transparent layers as the liquid crystal lens 100 </ b> A according to the embodiment includes. A power supply circuit 40 connected to the electrode 20 is provided.
The liquid crystal lens 100 </ b> C of the second modification is different from the liquid crystal lens 100 </ b> A according to the embodiment. In the liquid crystal lens 100 </ b> C of the second modification, contrary to the embodiment, the two transparent electrodes 20 are both outside the plate 10. Is provided in each.
In the second modification, dielectric powder is disposed on at least one surface of the two plates 10 in the same manner and concentration distribution as in the embodiment.
In the liquid crystal lens 100C according to the second modification, the dielectric powder is applied to the surface of the plate 10 at the same time as or in place of the same method and concentration distribution as in the embodiment. It may be arranged on the inner surface of the transparent electrode 20.

<Modification 3>
A liquid crystal lens 100D according to Modification 3 will be described.
The liquid crystal lens 100D according to Modification 3 basically has the same configuration as the liquid crystal lens 100B according to Modification 1.
As shown in FIG. 5, the liquid crystal lens 100 </ b> D according to the modified example 3 includes the same two plates 10, two transparent electrodes 20, a liquid crystal layer 30, and two transparent materials as the liquid crystal lens B according to the modified example 1 includes. The power supply circuit 40 connected to the layer 50 and the two transparent electrodes 20 is provided.
The liquid crystal lens 100D of the modification 3 is different from the liquid crystal lens 100B according to the modification 1 in that the two transparent electrodes 20 of the liquid crystal lens 100D of the modification 3 are both of the plate 10 opposite to the case of the modification 1. The two transparent layers 50 are respectively provided between the plate 10 and the transparent electrode 20 which are provided on the outer side and in pairs.
In the third modification, the dielectric powder is disposed on one of the transparent layers 50 (for example, one surface of the transparent layer 50) by the same method and concentration distribution as in the first modification.
The transparent layer 50 provided with the concentration distribution by the dielectric powder as described above may be provided inside the two plates 10 (for example, in close contact with the inner surface of the two plates 10).
However, if the dielectric concentration distribution is formed only on one of the two transparent layers 50, the transparent layer 50 may be one layer.

<Modification 4>
A liquid crystal lens 100E according to Modification 4 will be described.
The liquid crystal lens 100E according to Modification 4 basically has the same configuration as the liquid crystal lens 100D according to Modification 3.
As shown in FIG. 6, the liquid crystal lens 100 </ b> E according to the modified example 4 includes the same two plates 10, two transparent electrodes 20, a liquid crystal layer 30, and two transparent materials as the liquid crystal lens 100 </ b> D according to the modified example 3 includes. The power supply circuit 40 connected to the layer 50 and the two transparent electrodes 20 is provided.
The liquid crystal lens 100E of the modification 4 is different from the liquid crystal lens 100D of the modification 3 in the liquid crystal lens 100D of the modification 4 in the case of the modification 3 between the pair of the plate 10 and the transparent electrode 20. The two transparent layers 50 respectively provided on the plate 10 are both provided inside the plate 10.
In the fourth modification, the dielectric powder is disposed on any one of the transparent layers 50 (for example, one surface of the transparent layer 50) in the same manner and concentration distribution as in the third modification.
If it is not necessary to form a dielectric concentration distribution in both of the two transparent layers 50, the transparent layer 50 that does not form the dielectric concentration distribution is not necessary. In that case, the transparent layer 50 is a single layer.

≪Glasses for both perspective
Next, a description will be given of bifocal glasses using the above-described liquid crystal lens 100 (any one of 100A to 100E) described in the section << Liquid crystal lens >>.
As shown in FIG. 7, the perspective glasses 300 are configured like glasses.
The perspective glasses 300 include two frames 210, a bridge 220 that connects the two frames 210, and a temple 230 that is attached to the outside of the two frames 210. The frame 210, the bridge 220, and the temple 230 can be made of, for example, metal, but are made of resin in this embodiment. The temple 230 may be configured to be foldable with respect to the frame 210. Further, a known nose pad may be provided on the inner portion of the bridge 220 or the frame 210.
In this embodiment, the frame 210 has a circular donut shape, although not necessarily limited thereto. The lens group X is fitted in the space inside both the frames 210. The lens group X corresponds to the lens structure in the present application. The configuration of the lens group X will be described later.

A control unit 110 is attached to the temple 230. In this embodiment, the control unit 110 is configured such that the power supply circuit 40 described in the section << Liquid Crystal Lens >> is housed in a resin case formed in a rectangular parallelepiped shape. The control unit 110 also houses a control circuit that controls the power supply circuit 40. 7 should originally describe the power supply circuit and the control circuit, but for simplicity, these illustrations are omitted in FIG. Since the control circuit is a well-known technique, the control circuit is configured to include a CPU and a memory (not shown). The CPU executes a program recorded in the memory so that the potential difference applied to the two transparent electrodes 20 is reduced. The power supply circuit 40 is controlled to automatically change at a predetermined timing.
A distance measuring mechanism 111 is provided in front of the control unit 110. The distance measuring mechanism 111 is an object that is a predetermined object in front of the user wearing the bifocal glasses 300 in front of the control unit 110 (this is an object that the user is likely to see. ) Is measured. Since the distance measuring mechanism 111 is well known in the technical field of digital cameras, a detailed description of its configuration is omitted. The control circuit receives information about the distance to the object from the distance measuring mechanism 111, and changes the potential difference applied to the two transparent electrodes 20 of the bifocal glasses 300 using the information. The power supply circuit is controlled. In a memory (not shown), data about a reference distance described later is recorded.

Next, the configuration of the lens group X will be described.
In this embodiment, the lens group X is configured as shown in FIG.
The lens group X is configured by a combination of the liquid crystal lens 100 and a concave lens 150 having negative power. Although not necessarily limited to this, the concave lens 150 is a biconcave lens.
As the liquid crystal lens, any one of the liquid crystal lenses 100 described in the section of “Liquid crystal lens” (any one of 100A to 100E) is fitted. As already described, the liquid crystal lens 100 includes two transparent plates 10, two layered transparent electrodes 20, a liquid crystal layer 30, and, in some cases, two transparent layers 50. However, these two transparent plates 10, two layered transparent electrodes 20, the liquid crystal layer 30, and the two transparent layers 50 that exist in some cases are all used when applied to the perspective glasses 300 of this embodiment. The shape corresponding to the shape of the space inside the frame 210 (that is, circular in this embodiment). More specifically, the plate 10 included in the liquid crystal lens 100 of the bifocal glasses 300 corresponds to the inner part of the broken line shown in FIG. That is, the liquid crystal lens 100 of the bifocal glasses 300 includes the plate 10 surrounded by a broken line in the liquid crystal lens shown in FIG. 2, the transparent electrode 20 and the liquid crystal layer 30 corresponding thereto, and in some cases. The transparent layer 50 is cut out. The transparent electrode 20 is connected to the power supply circuit 40 via the cable 41. Thereby, the potential difference between the two transparent electrodes 20 can be controlled by the power supply circuit 40.
As described in the embodiment, the liquid crystal lens 100 does not function as a lens or hardly functions as a lens when a potential difference is not applied between the transparent electrodes 20. On the other hand, the liquid crystal lens 100 has a positive power by applying a potential difference between the transparent electrodes 20. That is, in the liquid crystal lens 100 of this embodiment, as shown in FIG. 2, the concentration distribution of the dielectric powder is such that the concentration decreases as it approaches the center. In the liquid crystal lens 100 of this embodiment, when the potential difference applied between the transparent electrodes 20 is increased to some extent, the combined power of the liquid crystal lens 100 and the concave lens 150 is positive.
The concave lens 150 is arranged to be coaxial with the liquid crystal lens 100 when functioning as a lens. The positional relationship between the concave lens 150 and the liquid crystal lens 100 in the front-rear direction is not questioned.

The user uses the bifocal glasses 300 by putting two temples 230 on both ears in the same manner as normal glasses. In this state, the two lens groups X are respectively positioned in front of the user's right eye and left eye. When the user uses the bifocal glasses 300, the user sees the outside through the lens group X.
At this time, the power supply circuit 40 is controlled by the control circuit to dynamically change the potential difference between the two transparent electrodes 20 of the liquid crystal lens 100. Thereby, the liquid crystal lens 100 changes the focal length. The control circuit indicates that the data about the distance from the distance measuring mechanism 111 to the object received at that time indicates that the distance to the object is longer than a predetermined reference distance (for example, 60 cm in this embodiment). In such a case, a potential difference is applied between the two transparent electrodes 20 so that the liquid crystal lens 100 functions in the same manner as a lens of myopia glasses. In this case, no potential difference is applied between the two transparent electrodes 20. At this time, the combined power of the liquid crystal lens 100 and the concave lens 150 is negative, as in normal myopia glasses.
On the other hand, when the data about the distance from the distance measuring mechanism 111 to the object received at that time indicates that the distance to the object is closer than a predetermined reference distance, the control circuit A potential difference is applied between the two transparent electrodes 20 so that the lens 100 functions in the same manner as a lens for farsighted glasses. At this time, the combined power of the liquid crystal lens 100 and the concave lens 150 is positive as in normal far-sighted glasses.
Through the above-described operation, the user wearing the bifocal glasses 300 can see the outside world while wearing the myopic glasses when looking at the distance. The outside can be seen as if wearing spectacles for hyperopia. In either case, the user is not narrowed in the field of view as when wearing normal perspective glasses.
In this embodiment, there are two lens groups including the liquid crystal lens 100 and the control unit 110, one for the right eye and the other for the left eye, but it is also possible to use only one for either eye. .

The lens group X may be configured as shown in FIG.
The lens group X in this case is configured by a combination of the liquid crystal lens 100 and a convex lens 160 having a positive power. Although not necessarily limited to this, the convex lens 160 is a biconvex lens.
As described in the embodiment, the liquid crystal lens 100 does not function as a lens or hardly functions as a lens when a potential difference is not applied between the transparent electrodes 20. On the other hand, the liquid crystal lens 100 in this case has a negative power by applying a potential difference between the transparent electrodes 20. In other words, in the liquid crystal lens 100 of this embodiment, the density distribution of the dielectric powder increases as it approaches the center, contrary to the case shown in FIG. In the liquid crystal lens 100 of this embodiment, when the potential difference applied between the transparent electrodes 20 is increased to some extent, the combined power of the liquid crystal lens 100 and the convex lens 160 is negative.
In the case of having such a lens group X, the control circuit shows that the distance data from the distance measuring mechanism 111 to the object received at that time indicates that the distance to the object is closer than a predetermined reference distance. In the case where it is, a potential difference is applied between the two transparent electrodes 20 such that the liquid crystal lens 100 functions in the same manner as a lens for hyperopia. On the other hand, if the data about the distance from the distance measuring mechanism 111 to the object received at that time indicates that the distance to the object is longer than a predetermined reference distance, the control circuit A potential difference is applied between the two transparent electrodes 20 so that the lens 100 functions in the same manner as a lens for myopia glasses. In this case, a potential difference is applied between the two transparent electrodes 20 such that the power of the liquid crystal lens 100 has a negative power that exceeds the positive power of the convex lens 160.

10 plate 20 transparent electrode 30 liquid crystal 40 power supply circuit 50 transparent layer 41 cable 100 liquid crystal lens 110 control unit 210 frame 230 temple 300 perspective glasses

Claims (24)

Glasses comprising: a liquid crystal lens; and a fixing means configured like glasses for fixing the liquid crystal lens in front of the user's eyes,
The liquid crystal lens is
Two transparent plates arranged at a predetermined interval,
Two transparent electrodes provided in pairs with each of the plates along the two plates;
A liquid crystal layer disposed between the two transparent electrodes;
Voltage applying means for applying a desired voltage between the two transparent electrodes;
Have
When a voltage is applied between the two transparent electrodes, a refractive index distribution is generated in the liquid crystal layer, and
A distance measuring means for measuring a distance to an object estimated to be viewed by a user when wearing the glasses;
The voltage application means is configured to control a voltage applied between the two transparent electrodes based on a distance to the object measured by the distance measurement means.
glasses. It has a positive power and has a lens placed on the same optical axis as the liquid crystal lens,
In the liquid crystal lens, the refractive index distribution generated in the liquid crystal layer when the voltage applying unit applies a voltage between the two transparent electrodes indicates that the power of the liquid crystal lens including the liquid crystal layer is positive of the lens. It is something that produces negative power more than negating the power of
The spectacles according to claim 1. It has a negative power and has a lens placed on the same optical axis as the liquid crystal lens,
In the liquid crystal lens, the refractive index distribution generated in the liquid crystal layer when the voltage applying unit applies a voltage between the two transparent electrodes indicates that the power of the liquid crystal lens including the liquid crystal layer is negative of the lens. It is something that produces positive power more than negating the power of
The spectacles according to claim 1. A space between the two transparent electrodes is provided with a dielectric constant distribution forming means for providing a dielectric constant distribution in the surface direction of the two transparent electrodes.
The spectacles according to claim 1. The transparent electrode paired with the plate is provided on the outer side of the plate included in a pair of the two pairs of the plate and the transparent electrode, and the dielectric constant distribution forming means is provided on the inner side of the transparent electrode. Provided on the surface of
The glasses according to claim 4. The transparent electrode paired with the plate is provided outside the plate included in a pair of the two pairs of the plate and the transparent electrode, and the dielectric constant distribution forming unit is paired with the transparent electrode. Provided on the plate,
The glasses according to claim 4. The dielectric constant distribution forming means is provided on at least one surface of the plate.
The spectacles according to claim 6. The transparent electrode paired with the plate is provided inside the plate included in a pair of the two pairs of the plate and the transparent electrode, and the dielectric constant distribution forming means is provided on the inner side of the transparent electrode. Provided on the surface of
The glasses according to claim 4. The transparent electrode paired with the plate is provided inside the plate included in a pair of the two pairs of the plate and the transparent electrode, and the dielectric constant distribution forming means is provided on the inner side of the transparent electrode. Provided in a transparent transparent layer provided in
The glasses according to claim 4. The transparent electrode paired with the plate is provided on the outer side of the plate included in a pair of the two pairs of the plate and the transparent electrode, and the dielectric constant distribution forming means is provided on the inner side of the transparent electrode. Provided in a transparent transparent layer provided in
The glasses according to claim 4. The dielectric constant distribution forming means is provided on at least one surface of the transparent layer.
The spectacles according to claim 9 or 10. The dielectric constant distribution forming means is layered.
The glasses according to claim 4. The two plates are arranged in parallel to each other;
The spectacles according to claim 1. The two plates are both flat plates and are arranged in parallel to each other.
The spectacles according to claim 1. The dielectric constant distribution given by the dielectric constant distribution forming means is:
The refractive index of light when vertically incident on the two plates is such that it gradually increases or decreases with the optical axis as the center,
The glasses according to claim 4. The dielectric constant distribution given by the dielectric constant distribution forming means is:
It has a concentric distribution,
The spectacles according to claim 15. The dielectric constant distribution forming means is configured to form a dielectric constant distribution by a distribution of a concentration of a dielectric powder whose particle size does not affect the transparency of the liquid crystal lens.
The glasses according to claim 4. The dielectric constant distribution forming means forms the dielectric constant distribution by the distribution of the concentration of the dielectric powder whose particle size does not affect the transparency of the liquid crystal lens. The concentration distribution of the powder is formed on the inner surface of the transparent electrode,
The spectacles according to claim 5 or 8. The dielectric constant distribution forming means forms the dielectric constant distribution by the distribution of the concentration of the dielectric powder whose particle size does not affect the transparency of the liquid crystal lens. The concentration distribution of the powder is formed on at least one surface of the plate,
The eyeglasses according to claim 7. The dielectric constant distribution forming means forms the dielectric constant distribution by the distribution of the concentration of the dielectric powder whose particle size does not affect the transparency of the liquid crystal lens. The concentration distribution of the powder is formed on at least one surface of the transparent layer,
The spectacles according to claim 11. The dielectric is barium titanate.
The spectacles according to any one of claims 17 to 20. A determination means for determining whether a distance to the object is larger or smaller than a reference distance which is a predetermined distance;
The voltage application means, when the determination means determines that the distance to the object is greater than the reference distance, the power after the combination of the liquid crystal lens and the lens is negative, When the determination unit determines that the distance to the object is smaller than the reference distance, the liquid crystal lens and the lens are combined between the two transparent electrodes so that the combined power becomes positive. The voltage to be applied is controlled,
The spectacles according to claim 2 or 3. The distance measuring means is configured to measure the distance to the target object as an object in the front direction of the user's face.
The spectacles according to claim 1. Glasses comprising: a variable focus lens; and a fixing means configured like glasses for fixing the variable focus lens in front of a user's eye,
The variable focus lens is:
Two transparent plates arranged at a predetermined interval,
Two transparent electrodes provided in pairs with each of the plates along the two plates;
A layer disposed between the two transparent electrodes;
Voltage applying means for applying a desired voltage between the two transparent electrodes;
Have
When a voltage is applied between the two transparent electrodes, a refractive index distribution is generated in the layer,
A distance measuring means for measuring a distance to an object estimated to be viewed by a user when wearing the glasses;
The voltage application means is configured to control a voltage applied between the two transparent electrodes based on a distance to the object measured by the distance measurement means.
glasses.