JP7159612B2 - dimmer - Google Patents

Description

The present invention relates to a light adjuster provided with an optical element that modulates the transmission state of light by electrical control.

As the type of optical element, a liquid crystal element, an electrochromic material, a suspended particle device (SPD), or the like is appropriately selected according to the visual effect required by the light adjuster. Hereinafter, in this specification, a liquid crystal element will be described as an example of an optical element.

Liquid crystal display devices are used as general display devices in various fields such as information display devices such as numerical values and image display devices such as video.

In a display device using a liquid crystal material, liquid crystal molecules are oriented and sandwiched between substrates having electrodes arranged at regular intervals, and these are sandwiched between two polarizing plates. By driving the liquid crystals in parallel, the transmittance of the polarized light is changed, thereby enabling display by modulation of the transmissive state and the light shielded state in units of cells (pixels).

On the other hand, in areas such as windows in residential spaces such as buildings and automobiles, studies are being conducted on light control glass that has optical functions to keep the living space comfortable in response to changes in the external environment. have been made (eg, Non-Patent Document 1).

In the case of using a liquid crystal material for such a light control glass, unlike the system for the display device described above, a liquid crystal display element with high light utilization efficiency without using a polarizing plate is used. There is a liquid crystal display element that switches between a (transparent state) and a scattering state (opaque state). Those using polymer network liquid crystal (PNLC) having liquid crystal molecules, or polymer dispersed liquid crystal (PDLC) having liquid crystal molecules dispersed in a polymer. is known, and is employed as an element that exhibits a state change of transparent-scattering instead of transmissive-light-shielding.

In existing liquid crystal display devices and light control glass, rigid glass plates are often used as the substrates (base materials) that sandwich the liquid crystal material, and most of the devices (display surfaces) have a flat plate shape.

Recently, it has become possible to use a flexible resin sheet or a thin plate glass with a thickness of 100 μm or less as a base material, and the application of the device (display surface) to not only a flat surface but also a curved surface has been realized.

NEW GLASS Vol. 13 No. 1 1998 P48-51 In addition to buildings and automobiles, various and complex designs are used in order to produce high-quality design and a sense of luxury in railway vehicles, ships, windows of aircraft, screens for digital signage, and partitions. There is also a demand for realization of corresponding non-flat devices (display surfaces), and followability to surface designs having three-dimensional shapes such as spherical surfaces is required.

Even if the base material is a "sheet" made of a flexible material, it is difficult to faithfully follow a three-dimensional shape that requires curvature changes in two or more directions (axes). A flat liquid crystal display device (light adjuster) cannot handle it.

An object of the present invention is to propose a light control body that can be applied to surface designs having various three-dimensional shapes.

The dimmer according to the present invention is
a cylindrical transparent substrate provided with a transparent electrode over the entire inner wall surface;
a rod-shaped transparent electrode disposed substantially on the center axis of the cylindrical transparent substrate;
and an optical element that is provided without gaps in a space defined by the cylindrical transparent substrate and the rod-shaped transparent electrode, and that changes the transmission state of incident light by electrical control.

A light control body having a very novel shape of "cylindrical" or "fiber-shaped" instead of a flat "sheet-shaped" is provided, and it will have superiority in application to various and complicated surface designs. In addition, since the sealing structure of the peripheral portion is simpler than that of a sheet-shaped light control body, problems such as deterioration of optical elements (liquid crystals, etc.) and peeling of the light control body can be eliminated.

An explanatory view showing a main part of a "cylindrical" light control body according to an embodiment of the present invention. Explanatory drawing which shows the principal part of the "flat" light control body which concerns on a prior art. Explanatory drawing which shows the structural example of the whole light control body containing a feeder circuit structure. Explanatory drawing which shows an example of the manufacturing method of the light control body which concerns on this embodiment in process order. An explanatory view showing a usage example of the light adjuster according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking the case of PNLC as an example.

However, the light adjuster according to the present invention is not limited by the following description. For example, the present invention is equally applicable to PDLC. For convenience of explanation, the figures may be exaggerated to a size different from the actual scale.

In PNLC, the display becomes opaque (scattered state) when the liquid crystal molecules are arranged irregularly along the mesh-like polymer fibers inside the liquid crystal layer, and the display becomes opaque (scattered state) when the liquid crystal molecules are aligned perpendicular to the display surface. , the display becomes transparent (transmissive state). In PDLC, a (liquid or capsule) liquid crystal material containing liquid crystal molecules is provided inside each polymer formed from a cured resin material in a polymer matrix. Depending on the orientation state, the scattering state and transmission state are modulated as the refractive index difference with the polymer matrix changes. There are two types of light control films using PNLC or PDLC as a light control layer, normal mode and reverse mode, depending on the mode of use. The normal mode refers to a mode in which a transmission state is obtained by applying a voltage and a scattering state is obtained by removing an electric field. In addition, the reverse mode is a mode in which a transmission state occurs when no voltage is applied, and a scattering state occurs when a voltage is applied.

A light control film having a light control layer of normal type PNLC is generally manufactured as follows. First, a mixture of a liquid crystal and a photopolymerizable compound (monomer) is sandwiched between a pair of transparent substrates (laminated transparent electrodes). Next, by irradiating ultraviolet rays under certain conditions, the photopolymerizable compound in the liquid crystal is changed into a polymer by photopolymerization. Photopolymerization and cross-linking form a polymer network with countless fine domains (macromolecular voids) in the liquid crystal.

FIG. 1 is an explanatory diagram showing a main part of a “cylindrical” light control body 10 according to this embodiment. The light control body 10 has a light control layer 2 . The light control layer 2 is of the PNLC type with a polymer network and liquid crystal molecules. The light control layer 2 is enclosed inside a tubular base material 1 having a transparent electrode 3 made of a transparent conductive material formed on the inner peripheral surface thereof. A rod-shaped electrode 4 is provided inside the enclosed light control layer (PNLC) 2 . In FIG. 1, the cross-sectional shape of the "cylindrical" is shown as a substantially cylindrical shape, but the cross-sectional shape is not limited to this. For example, the light adjuster may have a prismatic shape (having a rectangular cross section) as long as it does not affect the driving of the optical element. Regardless of the cross-sectional shape, it has a substantially concentric structure in which the rod-shaped electrode 4 is arranged in the core portion, the light control layer 2 is arranged in the clad portion, the transparent electrode 3 is arranged in the outer circumference, and the cylindrical substrate 1 is arranged in the outermost circumference. Become. The light modulating layer 2, the transparent electrode 3, and the tubular substrate 1 all have hollow tubular shapes.

For comparison, FIG. 2 is an explanatory view showing the essential parts of a conventional "flat" light control body 20. As shown in FIG. The light control body 20 has a light control layer 12 . The light control layer 12 is of the PNLC type with a polymer network and liquid crystal molecules. The light control layer 12 is sandwiched between substrate films 11a and 11b on which transparent electrodes 13a and 13b made of a transparent conductive material are formed (on the side facing the light control layer 12). The base films 11a and 11b, the transparent electrodes 13a and 13b, and the light control layer 12 (also the light control body 20) all have a flat plate shape.

In the case of FIG. 2, the light modulating layer (PNLC) 12 is modulated by the voltage applied between the transparent electrodes 13a and 13b located on both sides. On the other hand, in the case of FIG. 1, the light modulating layer (PNLC) 2 is modulated by the voltage applied between the transparent electrode 3 and the rod-shaped electrode 4 .

Polyethylene terephthalate (PET) film, polyethylene (PE) film, polycarbonate (PC) film, acrylic film, thin plate glass, etc. can be used for the base films 11a and 11b constituting the transparent conductive films (11a+13a, 11b+13b). . By using these base films, flexibility and pliability are high. Therefore, in addition to using the light control body 10 by laminating it on flat glass, it can be applied to a curved surface shape, rolled up and stored, etc. There is an advantage that the degree of freedom in handling is high. However, as described above, it is difficult to faithfully follow a shape that requires curvature changes in two or more directions (axes), and application to various three-dimensional shapes is limited.

In the embodiment of FIG. 1 as well, members having the same materials and sizes as in the prior art are adopted as the substrate 1, the light control layer 2, and the transparent electrode 3. As shown in FIG.

As the rod-shaped electrode 4, a structure in which the surface of a rod-shaped core material is coated with a metal oxide or a conductive polymer, or a structure in which a metal such as copper or aluminum is processed into a rod shape is selected. As the core material, a transparent plastic material or glass material is selected in order to ensure the transparency of the electrode 4 . As the plastic material, PET, PE, PC, acryl, etc. can be used.

The light modulating layer 2 shows a behavior in which there is almost no unreacted component in the phase separation, and the polymer network and the liquid crystal region are clearly separated with high purity. In addition, it is possible to realize an ideal alignment state without performing a pretilt alignment treatment by rubbing the transparent electrodes (13a, 13b), and the liquid crystal molecules are almost uniformly distributed in each domain divided by the polymer network. will be oriented.

The size of the domain of PNLC is as fine as about 1 μm compared to the fine particles (approximately 2 to 10 μm diameter) in the light diffusion sheet and dispersed nematic liquid crystal droplets (generally several μm diameter) in PDLC, and Rayleigh scattering (Wavelength-selective scattering) is not caused, and scattering in a wide wavelength range including at least visible light region wavelengths (400 to 780 nm) is efficiently generated.

The driving voltage of a PNLC generally depends on the structural properties of the polymer network (domain size and shape, thickness of the polymer network, etc.), and the structure of the polymer network and the resulting degree of light transmission and scattering. In relation, the drive voltage is determined. In the voltage range of 100 V or less, in order to construct a PNLC that can obtain a sufficient degree of light transmission and scattering, each domain must have an appropriate size and a uniform shape. It is necessary to form a polymer network as follows. In the present invention, the domain size, which depends on the polymer network structure, is controlled to be 3 μm or less, preferably 2 μm or less, more preferably about 1 μm.

In a reverse type device using PNLC or PDLC, a liquid crystal alignment layer (vertical alignment film) for vertically aligning the liquid crystal is used because the liquid crystal must be aligned vertically.

At present, liquid crystal alignment layers that are mainly used industrially are organic films made of polyimide-based polymers that are excellent in durability and suitable for controlling the pretilt angle of liquid crystals. As the polyimide-based polymer, a polyamic acid that is a polyimide precursor, a polyimide obtained by imidating a polyamic acid, or the like is used. The liquid crystal alignment layer is produced from the liquid crystal aligning agent using these polymers.

In the light control body 10 in the embodiment shown in FIG. 1, a vertical alignment film (not shown) is formed on the surface of at least one of the transparent electrode 3 and the rod-shaped electrode 4, and no voltage is applied to the light control layer 2. In some cases, the liquid crystal molecules are aligned such that the longitudinal direction of the liquid crystal molecules is aligned with the normal direction of the vertical alignment film. As a result, the reverse type light control layer 2 (PNLC) is in a low haze state when no voltage is applied, and has high transparency.

FIGS. 3A and 3B are explanatory diagrams showing an example of the overall structure of the light adjuster 10 including a circuit configuration for supplying power from the power supply 8 to the light adjuster 10 through lead wires (wirings) 9. FIG.

In addition, in FIG. 3(b), the same reference numerals are used for the constituent elements exhibiting the same or similar functions as those in FIG. omitted.

FIG. 3A shows a circuit configuration in which power is supplied from both ends of a cylindrical light control body 10. Current supplied from a power source 8 is passed through a rod-shaped electrode 4 via a lead wire (wiring) 9 from the left side. A lead wire (wiring) 9 leads to the transparent electrode 3 from the right side.

FIG. 3(b) shows a circuit configuration in which power is supplied from one end of a cylindrical light adjuster 10. Current supplied from a power source 8 is led from the left side to a rod-shaped electrode 4 via a lead wire (wiring) 9. Similarly, the transparent electrode 3 is passed through by a lead wire (wiring) 9 from the left side. In the case of FIG. 3B, there is no need to use the lead wire (wiring) 9 longer than the length of the tubular (or fibrous) light adjuster 10 .

On the other hand, when the length of the cylindrical light control body is several meters, with the one-sided electrode as shown in FIG. Although it sometimes becomes uneven, there is an advantage that the voltage difference is eliminated by taking the electrodes at both ends as shown in FIG. 3(a).

3(a) and 3(b), the transparent electrode 3 and the rod-like electrode 4 are shown by dotted lines. It has a film structure, and the rod-like electrode 4 is continuous in the longitudinal direction of the cylindrical base material 1 .

In addition, the liquid crystal layer is prone to deterioration due to acid, moisture, ultraviolet rays, etc. In particular, the edge of the sheet where the liquid crystal layer is sandwiched (periphery) is likely to come into contact with moisture, acid, ultraviolet rays, etc. Deterioration is likely to occur.

Furthermore, the joints tend to peel off as air enters from the sheet edges (peripheries).

Therefore, in the case of a sheet-shaped liquid crystal display device, in the case of a rectangular shape, the liquid crystal layer is exposed at the edges of the sheet (periphery) along the four sides. above), sealing with an encapsulant is mandatory.

In the figure, a sealing portion 5 made of a sealing material for suppressing deterioration of the light control layer 2 (liquid crystal) is formed on the cross section of both ends of the cylindrical light control body 10 . In FIG. 3A, the seal portion 5 is formed only on the cross section, and in FIG. , the protective measures for the light modulating layer 2 (liquid crystal) by preventing peeling of the seal portion 5 and peeling of the cylindrical base material 1 are further strengthened. In either case, the structure is simpler than sealing at the sheet ends (peripherals) extending over the four sides of the sheet-shaped light control body.

FIG. 4 is an explanatory view showing an example of a method for manufacturing the light control body 10 according to the present embodiment in order of steps. Depending on the configuration of the light control body, it is natural that other suitable manufacturing methods may be employed, and the following description does not limit the manufacturing method of the light control body.
(a) A flat base sheet 1 made of a plastic material is formed by pressing. The sheet 1 illustrated on the right side of FIG. 4(a) has a shape similar to a semi-cylindrical cylindrical lens group, and is obtained by heat embossing using a stamper 40 having the opposite shape of the shape.
(b) A transparent conductive film is formed on one surface of the substrate sheet 1 (the inner peripheral surface of the concave portion: the upper side in the figure) by a sputtering method or the like to form the transparent electrode 3 .
(c) On the surface on which the transparent electrode 3 is formed, the concave portion is filled and liquid crystal is applied to form the light control layer 2 . (d) A rod-shaped electrode 4 is placed at the center of curvature of the semi-cylindrical cylindrical lens.
(e) Further liquid crystal is applied.
(f) The sheet having the form of (b) on which the transparent electrode 3 is formed is placed so that the transparent electrode 3 side faces the light control layer 2 side, and is adjusted into a "cylindrical" space defined by the recesses of each other. Bond (laminate) such that the optical layer 2 is filled. At this time, the transparent electrodes 3 formed on the upper and lower sheets come into contact with each other at the boundary between the semi-cylindrical cylindrical lenses, and pressure is applied to the extent that they form an "arc" in cross-section and are electrically connected.
(g) An unnecessary portion (dotted line) of the cylindrical (fiber-like) light control body 10 formed by concentrically arranging the rod-shaped electrode 4, the light control layer 2, the transparent electrode 3, and the base material 1 is cut.

As described above, the light adjuster 10 having the configuration shown in FIG. 1 is manufactured.

FIG. 5 shows a usage example of the light adjuster according to this embodiment.

It is assumed that the "side surface with curvature" of a columnar solid 30 having upper and lower ellipses A and B with different shapes (and areas) shown in FIG.

Conventionally, a flat sheet-like light control body cannot be covered with a single sheet so as to follow a surface whose curvature varies from place to place.

As outlined in FIG. 5(b), by arranging the cylindrical (fiber-shaped) light control bodies 10 in a row, it is possible to fill the surface with a complicated shape. The individual light adjusters 10 are arranged as a light adjuster group (denoted as 10x in the figure) arranged so as to extend from the ellipse A (upper) to the ellipse B (lower) along the side surface of the solid 30. Alternatively, a light control body group (indicated as 10y in the figure) is formed by arranging the individual light control bodies 10 with curvature so as to extend along the circumferential direction parallel to the ellipses A and B. may be placed as Alternatively, 10x and 10y can be used in combination (furthermore, both can be used in the form of a knitted cloth).

According to the light control body of the present embodiment as described above, it is possible to provide a light control body having a very novel shape such as a "cylindrical" or "fiber-like" shape instead of a flat "sheet-like" shape. This makes it superior in application to diverse and complex surface designs. In addition, since the sealing structure of the peripheral portion is simpler than that of a sheet-shaped light control body, problems such as deterioration of optical elements (liquid crystals, etc.) and peeling of the light control body can be eliminated.

The present invention is not limited to the embodiments described above, and can be applied in modifications such as those exemplified below without departing from the scope of the invention.
(1) A liquid crystal element other than PNLC, an electrochromic material, and a suspended particle (SPD) are adopted as the light control layer.
(2) Use a non-cylindrical light control body (such as a prism) as long as it does not affect the driving of the optical element.
(3) Depending on the selection of the optical element used for the light adjuster, the variation of expression of the transmission state becomes more diversified. For example, when adopting a liquid crystal material containing a dye as the PNLC described in the embodiments, it is possible to switch not only "transparent-cloudy (scattering)" but also "transparent-colored scattering", including hue change. display is possible. In addition, when a translucent colored plastic is used as the cylindrical base material, display including a synergistic effect with the hue of the cylindrical base material is possible.

10, 20 light control body 1 base material 2 light control layer 3 transparent electrode 4 bar electrode 8 power supply 9 lead wire (wiring)
11 (a, b) base film 12 light control layer 13 (a, b) transparent electrode 30 solid 40 stamper

Claims (6)

a cylindrical transparent substrate provided with a transparent electrode over the entire inner wall surface;
a rod-shaped transparent electrode disposed substantially on the center axis of the cylindrical transparent substrate;
and an optical element that is provided without gaps in a space defined by the cylindrical transparent base material and the rod-shaped transparent electrode, and that changes the scattering state and the transmission state of light incident from the display surface by electrical control. ,
The optical element is a polymer-dispersed liquid crystal (PDLC) in which liquid crystal molecules are dispersed in a polymer, or is formed in a gap formed inside a polymer network made of a resin formed in a three-dimensional network. A polymer network liquid crystal (PNLC) having liquid crystal molecules arranged in
A light adjuster in which the liquid crystal molecules are aligned perpendicularly to the display surface in the transmissive state . 2. A light control body according to claim 1, wherein the transparent base material has a substantially cylindrical shape. 3. The light modulating body according to claim 1, wherein the transparent substrate is selected from PET, polycarbonate resin, acrylic resin, and glass. The light control body according to any one of claims 1 to 3, wherein the rod-shaped electrode is formed by coating a surface of a rod-shaped core material selected from transparent plastic materials or glass materials with a metal oxide or a conductive polymer. . Both ends of the cylindrical light control body are cut, and the cross section where the sealed optical element and the rod-shaped electrode are exposed is sealed with an insulating resin material, and the transparent electrode and the transparent electrode are connected from at least one of both ends of the light control body. 5. The light adjuster according to any one of claims 1 to 4, wherein the rod-shaped electrode is connected to wiring for supplying power. The light adjuster according to any one of claims 1 to 5, wherein the optical element changes the transmission state of incident light in at least two stages.

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