JP7434733B2 - Light control components, light control devices - Google Patents

Description

Embodiments of the present disclosure relate to a light control member and a light control device that can change light transmittance.

BACKGROUND ART Light control members that use liquid crystals to change light transmittance have been known.
However, although light control members using liquid crystals have a fast response speed for changes in transmittance, the difference between the maximum and minimum values of transmittance (hereinafter also referred to as the dynamic range of transmittance) is narrow, and the dynamic range is wider. It is requested to do so.
Further, light control members using photochromic materials have also been known (for example, Patent Document 1). A light control member using a photochromic material can widen the dynamic range of transmittance.
However, light control members that use photochromic materials change their transmittance when they receive light from the outside, so the transmittance changes depending on the environmental light, and the transmittance can be changed as necessary. The response speed was actually slow.

Japanese Patent Application Publication No. 6-227845

An object of the embodiments of the present disclosure is to provide a light control member and a light control device that can widen the dynamic range of transmittance and have a fast response speed to changes in transmittance.

Embodiments of the present disclosure solve the above problems by the following solution means. Note that in order to facilitate understanding, the description will be given with reference numerals corresponding to the embodiments of the present disclosure, but the present disclosure is not limited thereto.

The first disclosed embodiment includes a photochromic layer (11, 18) whose transmittance changes when receiving excitation light in a specific wavelength range, and a photochromic layer (11, 18) disposed on the first surface side of the photochromic layer (11, 18), a first shielding layer (12) that shields at least a portion of the excitation light; and a second shielding layer that is disposed on the second surface side of the photochromic layer (11, 18) and that shields at least a portion of the excitation light. (13) and a light control member (10, 10B).

A second disclosed embodiment is a light control member (10, 10B) according to the first invention, which is arranged between the first shielding layer (12) and the second shielding layer (13), comprising a light guide layer (14) that guides light incident from the end of the light control member (10, 10B) and emits at least part of the light toward the photochromic layer (11, 18); This is a characteristic light control member (10, 10B).

A third disclosed embodiment is a light control member (10, 10B) according to the second invention, in which the light guide layer (14) includes a high refractive index layer (15, 15B) and a high refractive index layer (15, 15B). a first low refractive index layer (16) disposed on the first surface side of the layer (15, 15B) and having a lower refractive index than the high refractive index layer (15, 15B); and the high refractive index layer (15, A second low refractive index layer (17) disposed on the second surface side of the light control member (15B) and having a lower refractive index than the high refractive index layer (15, 15B). 10, 10B).

A fourth embodiment of the disclosure is a light control member (10, 10B) according to the second invention or the third invention, in which the light guide layer (14) has a direction in which a part of the guided light travels. The light control member (10, 10B) is characterized by comprising a course changing part (15a, 15Ba) that changes the direction of the light.

A fifth disclosed embodiment is a light control member (10B) according to any one of the second to fourth inventions, in which the photochromic layer (11, 18) is a light guiding layer (14). This is a light control member (10B) characterized in that it is arranged on both sides of the light control member (10B).

A sixth disclosed embodiment provides a light control member (10, 10B) according to any one of the first to fifth inventions, and an end portion (10a) of the light control member (10, 10B). This is a light control device including an excitation light source (20) that irradiates the excitation light to the light source.

According to the embodiments of the present disclosure, it is possible to provide a light control member and a light control device that can widen the dynamic range of transmittance and have a fast response speed to change in transmittance.

FIG. 1 is a diagram showing a first embodiment of a light control device 1 including a light control member 10 according to an embodiment of the present disclosure. 2 is a cross-sectional view of the light control member 10 taken along the arrow AA in FIG. 1. FIG. It is a figure explaining the state where the excitation light source 20 is made to emit light in the light control device 1 of 1st Embodiment. 3 is a diagram showing a light control device 1B of a second embodiment in a cross section similar to FIG. 2. FIG. It is a figure explaining the state where the excitation light source 20 is made to emit light in the light control device 1B of 2nd Embodiment.

Hereinafter, the best mode for implementing the embodiments of the present disclosure will be described with reference to the drawings and the like.

(First embodiment)
FIG. 1 is a diagram showing a first embodiment of a light control device 1 including a light control member 10 according to an embodiment of the present disclosure. Note that the light control member 10 has a sheet-like shape, and FIG. 1 shows a plan view from a direction perpendicular to the sheet surface.
FIG. 2 is a cross-sectional view of the light control member 10 taken along the arrow AA in FIG.
Note that each figure shown below, including FIG. 1, is a schematic diagram, and the size and shape of each part are appropriately exaggerated or simplified to facilitate understanding.
In this specification, numerical values such as dimensions and material names of each member described are examples of embodiments, and are not limited to these, and may be appropriately selected and used.
In this specification, terms that specify shapes and geometrical conditions, such as terms such as parallel and orthogonal, have a strict meaning, but also have similar functions and have errors that can be considered parallel or orthogonal. It shall also include the state of having.
In this specification, terms such as plate, sheet, and film are used, but these terms are generally used in the order of thickness, such as plate, sheet, and film. This is also used in the specification. However, since there is no technical meaning in these different uses, these words can be replaced as appropriate.
In this specification, the sheet surface refers to the surface of each sheet that is in the planar direction of the sheet when the sheet is viewed as a whole. Note that the same applies to the plate surface and the film surface.

The light control device 1 includes a light control member 10 and an excitation light source 20. The light control device 1 is attached to, for example, a window of a building, a window of a vehicle, the back of a transmission screen, etc., and has a light control function of changing the transmittance of light.
The light control member 10 is a plate-shaped, sheet-shaped, or film-shaped optical member including a photochromic layer 11, a first shielding layer 12, a second shielding layer 13, and a light guiding layer 14, The shape viewed from the direction perpendicular to the sheet surface (shape in plan view) is a quadrilateral. In this embodiment, the light control member 10 has a rectangular shape in a plan view, but the shape in a plan view can be any shape as long as light can enter from the end where the excitation light source 20 is arranged. Good too.
Note that the light control member 10 of this embodiment does not need to be distinguished between the front and the back in the usage mode, but since it does not have a symmetrical configuration, in the following description, the side shown in FIG. 1, that is, the side shown in FIG. Although the left side will be referred to as the first surface side and the right side will be referred to as the second surface side, these directions may be changed as appropriate.

The photochromic layer 11 is a layer with photoresponsiveness that changes its transmittance when it receives excitation light in a specific wavelength range. The photochromic layer 11 of the present embodiment usually has a high visible light transmittance and is substantially transparent to visible light, and upon receiving ultraviolet light, the photochromic layer 11 changes color to gray or black, and the visible light transmittance decreases. state. Furthermore, when the photochromic layer 11 that has received the ultraviolet light finishes receiving the ultraviolet light, the transmittance of visible light gradually increases and returns to a transparent state.
The photochromic layer 11 is made of resin containing a photochromic material. Examples of photochromic materials include diarylethene compounds, spiropyran compounds, spiroperimidine compounds, fulgide compounds, hexaarylbiimidazole compounds, naphthopyran compounds, etc., but are not limited to these. It can be used as appropriate.

The photochromic layer 11 of this embodiment has a maximum transmittance of vertically incident visible light of 80% in the range of 430 nm to 700 nm when not discolored by ultraviolet light, and a minimum transmittance when the photochromic layer 11 is most deeply discolored by ultraviolet light. The ratio is 20% from 430 nm to 700 nm.

The first shielding layer 12 is a layer that is disposed on the first surface side of the photochromic layer 11 and blocks transmission of ultraviolet light, which is excitation light. More specifically, the first shielding layer 12 may be configured as an ultraviolet absorbing layer or as an ultraviolet reflecting layer. The first shielding layer 12 transmits light in a band other than the ultraviolet light to be blocked (its transmittance is sufficiently high), and is therefore substantially transparent to visible light. In this embodiment, the first shielding layer 12 is arranged on the outermost surface of the light control member 10 on the first surface side.

The second shielding layer 13 is a layer that is disposed on the second surface side of the photochromic layer 11 and blocks transmission of ultraviolet light, which is excitation light. More specifically, the second shielding layer 13 may be configured as an ultraviolet absorbing layer or as an ultraviolet reflecting layer. The second shielding layer 13 transmits light in a band other than the ultraviolet light to be blocked (its transmittance is sufficiently high), and is therefore substantially transparent to visible light. In this embodiment, the second shielding layer 13 is arranged on the outermost surface of the light control member 10 on the second surface side.

In this embodiment, the first shielding layer 12 and the second shielding layer 13 have the same structure and are configured as ultraviolet absorption layers, and absorb 90% or more of the vertically incident ultraviolet light in the range of 280 nm to 380 nm. Shield (absorb). More preferably, the first shielding layer 12 and the second shielding layer 13 shield (absorb) 95% or more of vertically incident ultraviolet light of 280 nm to 380 nm.

Since the photochromic layer 11 is sandwiched between the first shielding layer 12 and the second shielding layer 13, most of the ultraviolet light that reaches the light control member 10 from the first surface side and the second surface side It is shielded by the first shielding layer 12 and the second shielding layer 13 and does not reach the photochromic layer 11. Therefore, the photochromic layer 11 does not cause a change in transmittance due to external light.

The light guiding layer 14 is disposed between the first shielding layer 12 and the second shielding layer 13, and guides the light incident from the end of the light control member 10 to direct at least part of the light to the photochromic layer 11 side. emit to. In this embodiment, the light guide layer 14 is arranged closer to the first surface than the photochromic layer 11 is.
The light guide layer 14 includes a high refractive index layer 15 , a first low refractive index layer 16 , and a second low refractive index layer 17 .

The high refractive index layer 15 is a region to which guided excitation light (in this embodiment, ultraviolet light) is guided, and has a refractive index higher than that of the first low refractive index layer 16 and the second low refractive index layer 17. also has a high refractive index. Furthermore, it is desirable that the high refractive index layer 15 be formed using a material that has high transmittance for visible light and ultraviolet light, which is excitation light.
The first low refractive index layer 16 is disposed adjacent to the first surface side of the high refractive index layer 15 and has a lower refractive index than the high refractive index layer 15.
The second low refractive index layer 17 is disposed adjacent to the second surface side of the high refractive index layer 15 and has a lower refractive index than the high refractive index layer 15.
It is desirable that both the first low refractive index layer 16 and the second low refractive index layer 17 be formed using a material that has high transmittance for visible light and ultraviolet light, which is excitation light. In this embodiment, the first low refractive index layer 16 and the second low refractive index layer 17 are made of the same material.
The light guide layer 14 has the above-described structure, that is, the structure in which the high refractive index layer 15 is sandwiched between the first low refractive index layer 16 and the second low refractive index layer 17, so that the high refractive index layer 15 and the second low refractive index layer 15 are sandwiched between the high refractive index layer 15 and the second low refractive index layer 17. Excitation light from the excitation light source 20 reaches the interface with the first low refractive index layer 16 and the interface between the high refractive index layer 15 and the second low refractive index layer 17 at an angle larger than the critical angle. is totally reflected. Thereby, the excitation light is guided in the light guiding direction (the direction from the bottom to the top in FIGS. 1 and 2).

Further, the light guiding layer 14 includes a course changing section 15a that changes the direction in which a portion of the guided light travels. The course changing portion 15a of this embodiment is configured as a groove provided on the first surface side of the high refractive index layer 15. The course changing portion 15a extends in the direction perpendicular to the light guide direction, that is, in the left-right direction in FIG. 1, while maintaining the same groove shape. Moreover, a plurality of course changing parts 15a are arranged at intervals along the light guiding direction. Although the course changing portion 15a of the present embodiment has a rectangular cross-sectional shape as shown in FIG. It may be changed as appropriate.
Further, the inside of the groove shape of the course changing portion 15a may be filled with, for example, a resin forming the first low refractive index layer 16, or may be filled with another resin. However, if the inside of the groove shape of the course change part 15a is made into a void, there is a risk that the course change part 15a will be easily recognized due to dew condensation, etc., so it is desirable to fill it with some kind of resin.

The excitation light source 20 is disposed at the end 10a of the light control member 10, emits ultraviolet light as excitation light, and irradiates the end 10a with the excitation light. The excitation light irradiated to the end portion 10a enters into the high refractive index layer 15 from the end portion 10a and proceeds in the light guide direction. In this embodiment, the excitation light source 20 includes a plurality of point light sources such as LED (light emitting diodes) light sources.

Regarding the end portion 10a, although not shown, a light-shielding film, a light-shielding member, etc. are arranged at the end other than the end of the high refractive index layer 15, especially at the end of the photochromic layer 11, so that the excitation light does not enter directly. It is desirable to do so. Further, for the end portion 10b facing the end portion 10a and the end portions 10c and 10d extending along the light guide direction of the light control member 10, for example, an ultraviolet light reflective material that reflects excitation light is arranged. The excitation light may be returned, or an ultraviolet light reflecting material that absorbs the excitation light may be provided.

FIG. 3 is a diagram illustrating a state in which the excitation light source 20 emits light in the light control device 1 of the first embodiment. In addition, in FIG. 3, the state in which the photochromic layer 11 has changed color and the transmittance has decreased is expressed by showing dots densely.
When the excitation light source 20 emits light, the excitation light enters from the end 10a and travels as indicated by the arrow in FIG. As described above, the excitation light traveling through the high refractive index layer 15 is transmitted to the interface between the high refractive index layer 15 and the first low refractive index layer 16, and the interface between the high refractive index layer 15 and the second low refractive index layer. When it reaches these interfaces at an angle larger than the critical angle at the interface with 17, it is totally reflected. By repeating this, the excitation light is guided in the light guide direction. Furthermore, the direction of the excitation light that has reached the course changing section 15a is significantly changed. Here, the direction in which the excitation light is changed by the path changing section 15a varies, but some of the light is smaller than the critical angle at the interface between the high refractive index layer 15 and the second low refractive index layer 17. incident at an angle. This excitation light passes through this interface, exits from the light guide layer 14, reaches the photochromic layer 11, and the transmittance of the photochromic layer 11 decreases.

As described above, the path changing section 15a advances the excitation light toward the photochromic layer 11 by changing the path of the excitation light. Therefore, the distribution of the excitation light toward the photochromic layer 11 changes depending on the extent to which the excitation light hits the path changing portion 15a. In order to make the transmittance uniform throughout the photochromic layer 11, it is desirable to appropriately optimize the arrangement of the path changing portions 15a. Note that since the light guide layer 14 can be regarded as a surface light source of excitation light, a structure similar to that of a conventionally known surface light source device can be appropriately utilized as a specific structure of the path changing section 15a.

In the case of the form of the course changing part 15a as in this embodiment, the distribution of the amount of emitted excitation light can be made uniform by changing the depth of the groove of the course changing part 15a depending on the location. Specifically, the depth of the groove in the path changing section 15a on the side closer to the excitation light source 20 may be made smaller than the depth of the groove in the path changing section 15a on the side farther from the excitation light source 20. Note that the depth of the grooves of the plurality of course changing parts 15a may be changed for each course changing part 15a along the light guiding direction, or the depth of the grooves of the plurality of course changing parts 15a may be changed along the light guiding direction. It may be changed stepwise in units of multiple units.
Note that the distribution of the amount of emitted excitation light can also be made uniform by changing the width (width in the light guiding direction) of the course changing section 15a and the arrangement pitch thereof. However, it is desirable that the width of the course changing portion 15a and the arrangement pitch thereof be constant. This is to prevent the course changing section 15a from being visually recognized.

When the excitation light source 20 emits excitation light as shown in FIG. 3, the transmittance of the photochromic layer 11 decreases, and a so-called dimming effect can be exerted. Since the decrease in the transmittance of the photochromic layer 11 occurs approximately at the same time as the excitation light source 20 emits excitation light, the light control member 10 and the light control device 1 have a fast response speed to change in transmittance. In addition, as mentioned above, the photochromic layer 11 has a maximum transmittance of 80% and a minimum transmittance of 20%, so it has a higher dynamic range of transmittance than a light control member using liquid crystal, etc. The difference between the brightness and the brightness during dimming (when the transmittance decreases) is large, and the dimming member 10 and the dimming device 1 can have high utility value.
Further, the light control member 10 is configured with a first shielding layer 12 and a second shielding layer 13 sandwiching a photochromic layer 11 therebetween. Therefore, the photochromic layer 11 does not cause a change in transmittance due to external light. Further, it is also possible to prevent the excitation light from being emitted from the light control member 10.

(Second embodiment)
FIG. 4 is a cross-sectional view similar to FIG. 2 of the light control device 1B of the second embodiment.
The light control device 1B of the second embodiment is different from the high refractive index layer 15 of the first embodiment in that the high refractive index layer 15B of the light guiding layer 14B is different from the high refractive index layer 15 of the first embodiment, and that the light control device 1B further includes a second photochromic layer 18. This is different from the light control device 1 of the first embodiment, and other parts have the same configuration as the first embodiment. Therefore, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

The high refractive index layer 15B of the second embodiment is the same as the high refractive index layer 15 of the first embodiment, except that the shape of the course changing part 15Ba is different from the course changing part 15a of the first embodiment. . The course changing section 15Ba of the second embodiment is made of a light diffusing material mixed with the resin that constitutes the high refractive index layer 15B. As this light diffusing material, particles made of resin such as acrylic resin, epoxy resin, silicone resin, or inorganic particles can be used, and a combination of an inorganic diffusing material and an organic diffusing material may be used. good. It is preferable to use a diffusing material that is approximately spherical and has an average particle size of about 1 to 50 μm, and a more suitable range of average particle size for the diffusing material to be used is about 5 to 30 μm.

Further, the light control member 10B of the second embodiment further includes a second photochromic layer 18 in addition to the photochromic layer 11. The second photochromic layer 18 is arranged between the light guide layer 14B and the first shielding layer 12. The second photochromic layer 18 has a similar configuration to the photochromic layer 11. Therefore, in the light control member 10B of the second embodiment, photochromic layers are arranged on both sides of the light guide layer 14B.

FIG. 5 is a diagram illustrating a state in which the excitation light source 20 emits light in the light control device 1B of the second embodiment. In addition, in FIG. 5, the state in which the photochromic layer 11 and the second photochromic layer 18 are discolored and the transmittance is reduced is expressed by showing dots densely.
Also in the light control device 1B of the second embodiment, when the excitation light source 20 emits light, the excitation light enters from the end portion 10a and travels as indicated by the arrow in FIG. As in the first embodiment, the excitation light traveling through the high refractive index layer 15B is transmitted through the interface between the high refractive index layer 15B and the first low refractive index layer 16, and between the high refractive index layer 15B and the second low refractive index layer 16. At the interface with layer 17, when it reaches these interfaces at an angle greater than the critical angle, it is totally reflected. By repeating this, the excitation light is guided in the light guide direction. Furthermore, the direction of the excitation light that has reached the course changing section 15Ba is significantly changed. Here, the direction in which the excitation light is changed by the path changing section 15Ba varies, but some of the light travels through the interface between the high refractive index layer 15B and the second low refractive index layer 17 or the high refractive index layer 17. The light is incident on the interface between the layer 15B and the first low refractive index layer 16 at an angle smaller than the critical angle. This excitation light passes through these interfaces, exits from the light guide layer 14B, reaches the photochromic layer 11 and the second photochromic layer 18, and the transmittance of the photochromic layer 11 and the second photochromic layer 18 decreases. do.

According to the light control device 1B of the second embodiment, since the course changing portion 15Ba is made of a diffusing material, the light control member 10B can be manufactured more easily. Furthermore, since the second photochromic layer 18 is added, excitation light directed toward either the first surface or the second surface can be used for dimming, increasing the efficiency of excitation light utilization. Furthermore, it is possible to easily reduce the rate of decrease in the entire light control member 10B.

(Deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and these are also within the scope of the embodiments of the present disclosure.

(1) In each embodiment, a plurality of excitation light sources 20 are arranged along the end portion 10a, but the number of excitation light sources may be one, or a long light emitting section configured in a linear manner. You may use the light source which has. Moreover, in this embodiment, although the excitation light source 20 is arranged only on the end 10a side of the light control member 10, the excitation light source may be arranged at a plurality of ends.

(2) In the first embodiment, the course changing portion 15a extends continuously over the entire high refractive index layer 15 with the same cross-sectional shape in the left-right direction (direction intersecting the light guide direction) as shown in FIG. Although the example is shown in which they are discontinuously arranged, for example, they may be arranged discontinuously and discretely.

(3) In the second embodiment, a diffusing material is illustrated as the course changing part 15Ba, but other diffusing components may be used. As the diffusion component, for example, a metal compound, a porous substance containing gas, resin beads surrounding a metal compound, white fine particles, air bubbles, etc. may be used.

(4) In each embodiment, although the layer configurations of the light control members 10 and 10B are illustrated, these layer configurations may be changed as appropriate. For example, a second photochromic layer may be added to the first embodiment, or the course changing section 15a of the first embodiment and the course changing section 15Ba of the second embodiment may be provided in combination. Further, for example, a support plate for increasing the rigidity of the light control member may be further laminated, or other layers such as a printed layer or various optical functional layers may be laminated.

(5) In each embodiment, a photochromic layer that uses ultraviolet light as excitation light has been exemplified and explained. The present invention is not limited to this, and any photochromic layer whose transmittance changes depending on excitation light can be applied to the light control device of the embodiment of the present disclosure.

In addition, although each embodiment and modification can also be used in combination suitably, detailed description is abbreviate|omitted. Furthermore, the embodiments of the present disclosure are not limited to the embodiments described above.

1, 1B Light control device 10, 10B Light control member 10a, 10b, 10c, 10d End portion 11 Photochromic layer 12 First shielding layer 13 Second shielding layer 14, 14B Light guiding layer 15, 15B High refractive index layer 15a, 15Ba Path changing section 16 First low refractive index layer 17 Second low refractive index layer 18 Second photochromic layer 20 Excitation light source

Claims (3)

A photochromic layer whose transmittance changes when it receives excitation light in a specific wavelength range,
a first shielding layer disposed on the first surface side of the photochromic layer and shielding at least a portion of the excitation light;
a second shielding layer disposed on the second surface side of the photochromic layer and shielding at least a portion of the excitation light;
A light control member comprising:
A guide disposed between the first shielding layer and the second shielding layer, which guides excitation light incident from the end of the light control member and outputs at least a part of the excitation light to the photochromic layer side. Equipped with a light layer,
The light guiding layer is
a high refractive index layer;
a first low refractive index layer that is disposed on the first surface side of the high refractive index layer and has a lower refractive index than the high refractive index layer;
a second low refractive index layer disposed on the second surface side of the high refractive index layer and having a lower refractive index than the high refractive index layer;
Equipped with
The light guide layer includes a course changing part that changes the direction in which a part of the guided excitation light travels,
The course changing portion has a groove shape that extends in a direction that intersects the direction in which the light guide layer guides the excitation light, and the groove shape has a groove shape that extends in a direction perpendicular to the direction in which the groove shape extends. The cross-sectional shape is the same and extends;
A light control member characterized by: The light control member according to claim 1 ,
The photochromic layer is arranged on both sides of the light guide layer,
Light control member. The light control member according to claim 1 or claim 2 ,
an excitation light source that irradiates the excitation light to an end of the light control member;
A light control device.

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