Liquid crystal optical element

Abstract

It suppresses the peeling of the liquid crystal film. [Solution] According to one embodiment, the liquid crystal optical element comprises a substrate having a main surface, a first liquid crystal film disposed on the main surface and having a first side surface and a first cholesteric liquid crystal, a second liquid crystal film overlapping the first liquid crystal film and having a second side surface and a second cholesteric liquid crystal, and a fixing member formed in the shape of a frame surrounding the first liquid crystal film and the second liquid crystal film, in contact with the substrate, the first side surface, and the second side surface, and fixing the first liquid crystal film and the second liquid crystal film to the substrate.

Description

Technical Field

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[0001] Embodiments of the present invention relate to liquid crystal optical elements.

Background Art

[0002] For example, a liquid crystal optical element in which a plurality of liquid crystal layers are adhered with an adhesive layer has been proposed. According to this liquid crystal optical element, the first substrate includes a first liquid crystal layer having a first cholesteric liquid crystal on a first alignment film, the second substrate includes a second liquid crystal layer having a second cholesteric liquid crystal on a second alignment film, and the adhesive layer adheres the first substrate and the second substrate to each other. On the other hand, a technique of forming a liquid crystal film on a separate support substrate, then peeling the liquid crystal film from the support substrate, and transferring the peeled liquid crystal film onto a desired substrate has been studied. In this case, it is desired to suppress the peeling of the transferred liquid crystal film from the substrate.

Prior Art Documents

Patent Documents

[0003] <00​​​​​​​​​​​​​​​​​​​​​The device comprises a substrate having a main surface; a first liquid crystal film disposed on the main surface, having a first side surface and a first cholesteric liquid crystal; a second liquid crystal film overlapping the first liquid crystal film, having a second side surface and a second cholesteric liquid crystal; and a fixing member formed in the shape of a frame surrounding the first and second liquid crystal films, contacting the substrate, the first side surface, and the second side surface, and fixing the first and second liquid crystal films to the substrate. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a cross-sectional view showing one example configuration of the liquid crystal optical element 100. [Figure 2] Figure 2 is a plan view of the liquid crystal optical element 100 shown in Figure 1. [Figure 3] Figure 3 is a diagram illustrating an example of a combination of liquid crystal film 1 and liquid crystal film 2. [Figure 4] Figure 4 illustrates another example of a combination of liquid crystal film 1 and liquid crystal film 2. [Figure 5] Figure 5 is a cross-sectional view illustrating an example of cholesteric liquid crystal CL1 contained in liquid crystal film 1. [Figure 6] Figure 6 is a schematic plan view of the liquid crystal film 1. [Figure 7] Figure 7 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100. [Figure 8] Figure 8 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100. [Figure 9] Figure 9 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100. [Figure 10] Figure 10 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100. [Figure 11] Figure 11 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100. [Figure 12] Figure 12 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100. [Figure 13]Figure 13 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100. [Figure 14] Figure 14 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100. [Modes for carrying out the invention]

[0007] The embodiments will be described below with reference to the drawings. The disclosure is merely an example, and any modifications that a person skilled in the art could easily conceive of while maintaining the intent of the disclosure are naturally included within the scope of this disclosure. Furthermore, while drawings may schematically represent the width, thickness, shape, etc., of parts in a manner that is clearer than the actual embodiment, they are merely examples and do not limit the interpretation of this disclosure. In addition, in this specification and in each drawing, components that perform the same or similar functions as those described above in previously shown drawings are denoted by the same reference numerals, and redundant detailed explanations may be omitted as appropriate.

[0008] Furthermore, the drawings will include mutually orthogonal X, Y, and Z axes as needed to facilitate understanding. The direction along the X axis will be referred to as the first direction X, the direction along the Y axis as the second direction Y, and the direction along the Z axis as the third direction Z. The plane defined by the first direction X and the second direction Y will be referred to as the XY plane, the plane defined by the second direction Y and the third direction Z will be referred to as the YZ plane, and the plane defined by the first direction X and the third direction Z will be referred to as the XZ plane. Viewing various elements parallel to the third direction Z is called a plan view. Furthermore, terms referring to the positional relationship between two or more constituent elements, such as above, above, between, and opposite, include not only cases where the two or more constituent elements of the object are in direct contact, but also cases where they are separated from each other by gaps or other constituent elements.

[0009] Figure 1 is a cross-sectional view showing one example configuration of the liquid crystal optical element 100.

[0010] The liquid crystal optical element 100 comprises a substrate 10, a liquid crystal film 1, a liquid crystal film 2, and a fixing member 20.

[0011] The substrate 10 is a transparent substrate such as a glass plate or a synthetic resin plate. As will be described later, the substrate 10 may be an opaque substrate such as a silicon substrate or a metal substrate. The substrate 10 is formed in a flat plate shape and has a main surface 10A. The main surface 10A is a plane substantially parallel to the X-Y plane.

[0012] The liquid crystal film 1 is disposed on the main surface 10A and has a side surface 1S. In the illustrated example, the liquid crystal film 1 is in contact with the main surface 10A. There is no alignment film or adhesive layer interposed between the substrate 10 and the liquid crystal film 1. The side surface 1S includes a plane substantially parallel to the X-Z plane.

[0013] The liquid crystal film 2 overlaps the liquid crystal film 1. In the third direction Z, the liquid crystal film 1 is located between the substrate 10 and the liquid crystal film 2. In the illustrated example, the liquid crystal film 2 is in contact with the liquid crystal film 1. There is no adhesive layer interposed between the liquid crystal film 1 and the liquid crystal film 2.

[0014] Further, the liquid crystal film 2 has an upper surface 2A and a side surface 2S. The upper surface 2A is a surface on the side of the liquid crystal film 2 opposite to the side facing the liquid crystal film 1, and is a plane substantially parallel to the X-Y plane. The side surface 2S includes a plane substantially parallel to the X-Z plane. When the liquid crystal film 2 is formed in the same shape as the liquid crystal film 1, the side surface 2S is located directly above the side surface 1S in the third direction Z.

[0015] The fixing member 20 is continuously in contact with the main surface 10A of the substrate 10, the side surface 1S of the liquid crystal film 1, and the side surface 2S of the liquid crystal film 2, and fixes the liquid crystal film 1 and the liquid crystal film 2 to the substrate 10. In the illustrated example, the fixing member 20 does not cover the upper surface 2A.

[0016] The fixing member 20 has a first width W1 in a direction parallel to the main surface 10A (or the second direction Y) at a portion in contact with the side surface 2S, and has a second width W2 at a portion in contact with the main surface 10A. In the illustrated example, the second width W2 is substantially equal to the first width W1.

[0017] Figure 2 is a plan view of the liquid crystal optical element 100 shown in Figure 1.

[0018] In the illustrated example, the planar shapes of the substrate 10, liquid crystal film 1, and liquid crystal film 2 are all quadrilaterals, each having a pair of sides extending in a first direction X and a pair of sides extending in a second direction Y. Note that the planar shapes of the substrate 10, liquid crystal film 1, and liquid crystal film 2 may be other shapes such as polygons, circles, or ellipses. Sides 1S and 2S extend along all four sides. That is, each of side 1S and 2S includes a plane substantially parallel to the XZ plane as well as a plane substantially parallel to the YZ plane. The fixing member 20 is formed in a frame shape surrounding the liquid crystal film 1 and liquid crystal film 2, and is in contact with the entirety of side 1S and 2S along all four sides. Note that the fixing member 20 is not limited to the closed shape shown, and may have a portion of it interrupted.

[0019] Figure 3 is a diagram illustrating an example of a combination of liquid crystal film 1 and liquid crystal film 2.

[0020] The liquid crystal film 1 has a cholesteric liquid crystal CL1, as shown schematically in an enlarged view. The cholesteric liquid crystal CL1 has a helical pitch P1 along the third direction Z. The helical pitch represents one period of the helix (the layer thickness along the third direction Z required for the liquid crystal molecules to rotate 360 ​​degrees).

[0021] The liquid crystal film 2 has a cholesteric liquid crystal CL2, as shown schematically in an enlarged view. The cholesteric liquid crystal CL2 has a helical pitch P2 along a third direction Z. For example, the helical pitch P2 is equivalent to the helical pitch P1. The rotational direction of the cholesteric liquid crystal CL2 is different from the rotational direction of the cholesteric liquid crystal CL1.

[0022] Each of these liquid crystal films 1 and 2 is configured to reflect circularly polarized light in a selective reflection band determined according to the helical pitch P and the refractive index anisotropy Δn of the liquid crystal film. In this specification, "reflection" in a liquid crystal film refers to reflection accompanied by diffraction within the liquid crystal film.

[0023] Liquid crystal film 1 has a reflective surface 1R that reflects circularly polarized light corresponding to the rotational direction of the cholesteric liquid crystal CL1 within the selective reflection band. Liquid crystal film 2 has a reflective surface 2R that reflects circularly polarized light corresponding to the rotational direction of the cholesteric liquid crystal CL2 within the selective reflection band. In the illustrated example, both reflective surface 1R and reflective surface 2R are inclined with respect to the XY plane. In this specification, circularly polarized light may be strictly circularly polarized light or circularly polarized light that approximates elliptical polarization.

[0024] For example, when natural light, light LT0, is incident on liquid crystal films 1 and 2, liquid crystal film 1 reflects light LT1 at its reflective surface 1R, and liquid crystal film 2 reflects light LT2 at its reflective surface 2R. As described above, since the helical pitch P1 is equivalent to the helical pitch P2, light LT1 and light LT2 are light in the same wavelength band λ1. Furthermore, since the rotational directions of cholesteric liquid crystal CL1 and cholesteric liquid crystal CL2 are different, light LT1 and light LT2 are circularly polarized in opposite directions. For example, light LT1 is clockwise circularly polarized λ1a, and light LT2 is counterclockwise circularly polarized λ1b.

[0025] Figure 4 illustrates another example of a combination of liquid crystal film 1 and liquid crystal film 2.

[0026] The example shown in Figure 4 differs from the example shown in Figure 3 in that the helical pitch P2 is different from the helical pitch P1. In the illustrated example, the helical pitch P2 is greater than the helical pitch P1. In the illustrated example, the rotational directions of the cholesteric liquid crystal CL1 and cholesteric liquid crystal CL2 are the same, but they may be different.

[0027] For example, when natural light LT0 is incident on liquid crystal film 1 and liquid crystal film 2, liquid crystal film 1 reflects light LT1 at reflective surface 1R, and liquid crystal film 2 reflects light LT2 at reflective surface 2R. As described above, since the helical pitch P1 is different from the helical pitch P2, light LT1 and light LT2 are light in different wavelength bands. If the helical pitch P2 is larger than the helical pitch P1, the wavelength band λ2 of light LT2 reflected at reflective surface 2R is longer than the wavelength band λ1 of light LT1 reflected at reflective surface 1R.

[0028] In the illustrated example, since the rotation direction of cholesteric liquid crystal CL1 and cholesteric liquid crystal CL2 are the same, light LT1 and light LT2 are circularly polarized light rotating in the same direction.

[0029] Next, we will explain the configuration of the liquid crystal film. Here, we will describe liquid crystal film 1. Note that the configuration of liquid crystal film 2 is the same as that of liquid crystal film 1, except for the direction of rotation and the helical pitch.

[0030] Figure 5 is a cross-sectional view illustrating an example of cholesteric liquid crystal CL1 contained in liquid crystal film 1.

[0031] In Figure 5, the liquid crystal film 1 is shown enlarged in the third direction Z. For simplification, one liquid crystal molecule LM is shown as one of several liquid crystal molecules located in the same plane parallel to the XY plane, representing the liquid crystal molecules that make up the cholesteric liquid crystal CL1. The orientation direction of the shown liquid crystal molecule LM corresponds to the average orientation direction of the multiple liquid crystal molecules located in the same plane.

[0032] Focusing on one cholesteric liquid crystal CL1 enclosed by a dashed line, we see that the cholesteric liquid crystal CL is composed of multiple liquid crystal molecules LM that are spirally stacked along the third direction Z while rotating.

[0033] The orientation directions of multiple adjacent cholesteric liquid crystals CL1 along the second direction Y are different from each other. In multiple adjacent cholesteric liquid crystals CL1 along the second direction Y, the orientation directions of liquid crystal molecules LM11 located on the same plane are different from each other. The orientation directions of multiple liquid crystal molecules LM11 change continuously along the second direction Y.

[0034] The reflective surface 1R of the liquid crystal film 1, shown by the dashed line in the figure, is inclined with respect to the XY plane. The angle θα between the reflective surface 1R and the XY plane is acute. The reflective surface 1R corresponds to a surface where the orientation directions of the liquid crystal molecules LM are aligned, or a surface where the spatial phases are aligned (equal phase surface).

[0035] Such a liquid crystal film 1 is cured with the orientation direction of the liquid crystal molecules LM fixed. In other words, the orientation direction of the liquid crystal molecules LM is not controlled according to the electric field, as is the case with typical liquid crystal elements.

[0036] Figure 6 is a schematic plan view of the liquid crystal film 1.

[0037] Figure 6 shows an example of the spatial phase of cholesteric liquid crystal CL1. The spatial phase shown here is indicated by the orientation direction of the liquid crystal molecules LM11 contained in the cholesteric liquid crystal CL1, which are shown by the dashed circles.

[0038] For each of the cholesteric liquid crystals CL1 aligned along the second direction Y, the orientation direction of the liquid crystal molecules LM11 is different from that of the others. In other words, the spatial phases of the cholesteric liquid crystals CL1 differ along the second direction Y.

[0039] On the other hand, for each of the cholesteric liquid crystals CL1 aligned along the first direction X, the orientation direction of the liquid crystal molecules LM11 is substantially the same. In other words, the spatial phase of the cholesteric liquid crystals CL1 is substantially the same in the first direction X.

[0040] In particular, focusing on the cholesteric liquid crystal CL1 aligned in the second direction Y, the orientation direction of each liquid crystal molecule LM11 differs by a certain angle. That is, the orientation direction of multiple liquid crystal molecules LM11 aligned along the second direction Y changes linearly. Therefore, the spatial phase of multiple cholesteric liquid crystal CL1 aligned along the second direction Y changes linearly along the second direction Y. As a result, a reflective surface 1R tilted with respect to the XY plane is formed, as shown in Figure 5. "Linear change" here means, for example, that the amount of change in the orientation direction of the liquid crystal molecules LM11 can be expressed by a linear function. Note that the orientation direction of the liquid crystal molecules LM11 here corresponds to the long axis direction of the liquid crystal molecules LM11 in the XY plane.

[0041] Here, within the same plane, the period T is defined as the distance between two liquid crystal molecules LM11 when their orientation direction changes by 180 degrees in the second direction Y. In Figure 6, DP indicates the rotation direction of the cholesteric liquid crystal CL1. The tilt angle θα of the reflective surface 1R shown in Figure 5 is appropriately set by the period T and the helical pitch P.

[0042] Next, a brief explanation will be given regarding the manufacturing method of the liquid crystal optical element 100 described above.

[0043] First, liquid crystal film 1 and liquid crystal film 2 are prepared. Specifically, an alignment film is formed on a support substrate. The alignment film has an alignment axis of a predetermined alignment pattern. Then, liquid crystal material is applied onto the alignment film. The liquid crystal molecules contained in the liquid crystal material are arranged in a spiral shape by the alignment restricting force of the alignment film. The liquid crystal material is cured in a state where the liquid crystal molecules exhibit a cholesteric liquid crystal phase. This forms a liquid crystal film. The liquid crystal film thus formed is peeled off from the alignment film.

[0044] Next, the liquid crystal film 1 prepared using the method described above is placed on the substrate 10, and then the liquid crystal film 2 is placed on top of the liquid crystal film 1.

[0045] Next, a frame-shaped fixing member 20 is formed to surround the liquid crystal film 1 and the liquid crystal film 2. The fixing member 20 may be a pre-formed adhesive tape, or it may be made by applying a liquid adhesive and then curing it, or it may be made by depositing material using a method such as CVD (Chemical Vapor Deposition). As a result, the fixing member 20 adheres closely to the substrate 10, the liquid crystal film 1, and the liquid crystal film 2, respectively. The liquid crystal film 1 and the liquid crystal film 2 are fixed to the substrate 10 by such a fixing member 20.

[0046] In this way, in a liquid crystal optical element 100 manufactured by a method of transferring separately formed liquid crystal films 1 and 2 onto a desired substrate 10, peeling of the liquid crystal films 1 and 2 from the substrate 10 can be suppressed. Therefore, the quality and reliability of the liquid crystal optical element 100 can be improved.

[0047] Here are some examples of materials that can be used as the fixing member 20. Resin materials such as acrylic resin, vinyl chloride, polyethylene terephthalate, polycarbonate resin, polyvinyl alcohol, polyethylene, unaxially oriented polypropylene, biaxially oriented polypropylene, biaxially oriented polystyrene, polyvinylidene chloride, triacetylcellulose, polycarbonate, polyethersulfone, polyphenyl sulfide, polyimide, polyurethane, fluororesin, norbornene resin, and cycloolefin can be applied to the fixing member 20. Furthermore, silicon compounds such as silicon nitrides and silicon oxides can also be applied to the fixing member 20.

[0048] Next, other configuration examples will be described. Note that components similar to those in the above configuration examples will be given the same reference numerals, and redundant explanations may be omitted.

[0049] Figure 7 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100.

[0050] The configuration example shown in Figure 7 differs from the configuration example shown in Figure 1 in that the second width W2 is larger than the first width W1. That is, the fixing member 20 extends continuously from the side surface 2S toward the side surface 1S, and further extends continuously from the side surface 1S toward the main surface 10A, and contacts the main surface 10A. In the YZ cross-section of the liquid crystal optical element 100 as shown, the second width W2 along the second direction Y of the portion of the fixing member 20 that contacts the main surface 10A is larger than the first width W1 along the second direction Y of the portion of the fixing member 20 that contacts the side surface 2S. Although not shown, in the XZ cross-section as well, the second width W2 is larger than the first width W1. This increases the contact area between the fixing member 20 and the substrate 10, allowing the liquid crystal film 1 and liquid crystal film 2 to be more firmly fixed to the substrate 10.

[0051] Figure 8 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100.

[0052] The configuration example shown in Figure 8 differs from the configuration example shown in Figure 1 in that the fixing member 20 extends continuously from the side surface 2S of the liquid crystal film 2 toward the upper surface 2A and covers the upper surface 2A. In other words, the fixing member 20 covers the entire laminate of liquid crystal film 1 and liquid crystal film 2 and is in contact with the substrate 10. This provides the same effects as the configuration example shown in Figure 1, while also protecting the liquid crystal film 2. Therefore, the quality and reliability of the liquid crystal optical element 100 can be further improved.

[0053] Furthermore, in a liquid crystal optical element 100 through which light passes through the fixed member 20, it is desirable that the fixed member 20 be transparent and that the refractive index of the fixed member 20 and the liquid crystal film 2 be approximately the same, in order to suppress unwanted absorption and reflection of light by the fixed member 20. The refractive index of the fixed member 20 is, for example, 1.5 to 1.7.

[0054] Figure 9 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100.

[0055] The configuration example shown in Figure 9 differs from the configuration example shown in Figure 8 in that the second width W2 is larger than the first width W1. As a result, in addition to obtaining the same effects as the configuration example shown in Figure 8, the contact area between the fixing member 20 and the substrate 10 is increased, allowing the liquid crystal film 1 and liquid crystal film 2 to be more firmly fixed to the substrate 10.

[0056] In the configuration example shown in Figure 9, both the substrate 10 and the fixing member 20 are transparent. Therefore, each of the liquid crystal film 1 and liquid crystal film 2 can reflect a portion of the light incident through the substrate 10 and a portion of the light incident through the fixing member 20.

[0057] Figure 10 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100.

[0058] The configuration example shown in Figure 10 differs from the configuration example shown in Figure 9 in that the substrate 10 is transparent, while the fixing member 20 is opaque. In such a liquid crystal optical element 100, when light LT0 is incident through the substrate 10, the liquid crystal film 1 is configured to reflect light LT1 at its reflective surface 1R, and the liquid crystal film 2 is configured to reflect light LT2 at its reflective surface 2R. If the fixing member 20 is made of a black material, the light LT3 transmitted through the liquid crystal film 1 and the liquid crystal film 2 is absorbed by the fixing member 20.

[0059] This provides the same effects as the configuration example shown in Figure 9, and also suppresses the generation of unwanted reflected light inside the liquid crystal optical element 100.

[0060] Figure 11 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100.

[0061] The configuration example shown in Figure 11 differs from the configuration example shown in Figure 9 in that the fixing member 20 is transparent, while the substrate 10 is opaque. In such a liquid crystal optical element 100, when light LT0 is incident through the fixed member 20, the liquid crystal film 2 is configured to reflect light LT2 at the reflective surface 2R, and the liquid crystal film 1 is configured to reflect light LT1 at the reflective surface 1R. When the substrate 10 is made of a black material, the light LT3 transmitted through the liquid crystal film 1 and the liquid crystal film 2 is absorbed by the substrate 10.

[0062] This provides the same effects as the configuration example shown in Figure 9, and also suppresses the generation of unwanted reflected light inside the liquid crystal optical element 100.

[0063] Figure 12 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100.

[0064] The configuration example shown in Figure 12 differs from the configuration example shown in Figure 8 in that the fixing member 20 is in contact with the side surface 10S of the substrate 10. The substrate 10, liquid crystal film 1, and liquid crystal film 2 all have the same planar shape. The side surface 1S of liquid crystal film 1 and the side surface 2S of liquid crystal film 2 are located directly above the side surface 10S of the substrate 10 in the third direction Z. The fixing member 20 continuously covers the side surface 10S, side surface 1S, side surface 2S, and the top surface 2A.

[0065] The thickness of the substrate 10 along the third direction Z is greater than the thickness of the liquid crystal film 1 and liquid crystal film 2 along the third direction Z. In one example, the thickness of the liquid crystal film 1 and liquid crystal film 2 is several micrometers, while the thickness of the substrate 10 is several hundred micrometers or more. Therefore, the contact area between the side surface 10S of the substrate 10 and the fixing member 20 is greater than the contact area between the side surface 1S of the liquid crystal film 1 and the fixing member 20, and also greater than the contact area between the side surface 2S of the liquid crystal film 2 and the fixing member 20.

[0066] As a result, in addition to obtaining the same effects as the configuration example shown in Figure 8, the contact area between the fixing member 20 and the substrate 10 is increased, allowing the liquid crystal film 1 and liquid crystal film 2 to be more firmly fixed to the substrate 10.

[0067] Figure 13 is a cross-sectional view showing another configuration example of the liquid crystal optical element 100.

[0068] The configuration example shown in Figure 13 differs from the configuration example shown in Figure 12 in that an alignment film 30 is placed between the substrate 10 and the liquid crystal film 1. The fixing member 20 is in contact with the side surface 30S of the alignment film 30. Even in this configuration example, the same effects as the configuration example shown in Figure 12 can be obtained.

[0069] Figure 14 is a cross-sectional view showing another example of the configuration of the liquid crystal optical element 100.

[0070] The configuration example shown in Figure 14 differs from the configuration example shown in Figure 9 in that the liquid crystal optical element 100 comprises a laminate of three or more liquid crystal films. When multiple liquid crystal films are laminated, liquid crystal film 1 is located at the bottom layer of the laminate, liquid crystal film 2 is located at the top layer of the laminate, and the other liquid crystal films 3, 4, ... are located between liquid crystal film 1 and liquid crystal film 2. In the illustrated example, liquid crystal film 1 is in contact with the substrate 10. Liquid crystal film 2 is covered with a fixing member 20. There is no adhesive layer between the two liquid crystal films.

[0071] In one example, liquid crystal film 1 is configured to reflect circularly polarized light in the blue wavelength range as a selective reflection band, liquid crystal film 2 is configured to reflect circularly polarized light in the green wavelength range as a selective reflection band, and liquid crystal film 3 is configured to reflect circularly polarized light in the red wavelength range as a selective reflection band. With a liquid crystal optical element 100 like this example, it becomes possible to broaden the selectable reflection band.

[0072] In another example, liquid crystal film 1 is configured to reflect right-handed circularly polarized light in the blue wavelength range as a selective reflection band; liquid crystal film 2 is configured to reflect right-handed circularly polarized light in the green wavelength range as a selective reflection band; liquid crystal film 3 is configured to reflect right-handed circularly polarized light in the red wavelength range as a selective reflection band; liquid crystal film 4 is configured to reflect left-handed circularly polarized light in the blue wavelength range as a selective reflection band; liquid crystal film 5 is configured to reflect left-handed circularly polarized light in the green wavelength range as a selective reflection band; and liquid crystal film 6 is configured to reflect left-handed circularly polarized light in the red wavelength range as a selective reflection band.

[0073] According to this example of a liquid crystal optical element 100, it is possible to reflect both right-handed and left-handed circularly polarized light in the same wavelength range, thereby improving the efficiency of light utilization.

[0074] In the above embodiment, for example, liquid crystal film 1 corresponds to the first liquid crystal film, cholesteric liquid crystal CL1 corresponds to the first cholesteric liquid crystal, and side surface S1 corresponds to the first side surface. Liquid crystal film 2 corresponds to the second liquid crystal film, cholesteric liquid crystal CL2 corresponds to the second cholesteric liquid crystal, and side surface S2 corresponds to the second side surface.

[0075] As described above, according to this embodiment, it is possible to provide a liquid crystal optical element that can suppress peeling of the liquid crystal film.

[0076] While several embodiments of this disclosure have been described, these embodiments are presented as examples only and are not intended to limit the scope of the disclosure. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications are permitted without departing from the gist of the disclosure. These embodiments and their variations are included in the scope and gist of the disclosure, as well as in the disclosures described in the claims and their equivalents. [Explanation of Symbols]

[0077] 100...Liquid crystal optical elements 10... Circuit board 10A... Main surface 1…LCD film 1S…Side CL1…Cholesteric LCD 2…LCD film 2S…Side 2A…Top CL2…Cholesteric LCD 20… Fixing member

Claims

1. A substrate having a main surface, A first liquid crystal film is arranged on the main surface, has a first side surface, and has a first cholesteric liquid crystal, A second liquid crystal film overlapping the first liquid crystal film, having a second side surface and a second cholesteric liquid crystal, The device comprises a fixing member formed in the shape of a frame surrounding the first liquid crystal film and the second liquid crystal film, which contacts the substrate, the first side surface, and the second side surface, and fixes the first liquid crystal film and the second liquid crystal film to the substrate. Liquid crystal optical element.

2. The rotation direction of the first cholesteric liquid crystal is different from the rotation direction of the second cholesteric liquid crystal. The liquid crystal optical element according to claim 1.

3. The helical pitch of the first cholesteric liquid crystal is different from the helical pitch of the second cholesteric liquid crystal. The liquid crystal optical element according to claim 1.

4. The fixing member extends continuously from the first side surface toward the main surface and is in contact with the main surface. The liquid crystal optical element according to claim 1.

5. The fixing member has a first width in a direction parallel to the main surface in the portion that contacts the second side surface, and a second width in the portion that contacts the main surface. The second width is greater than the first width. The liquid crystal optical element according to claim 4.

6. The second liquid crystal film has an upper surface on the side opposite to the side facing the first liquid crystal film, The fixing member extends continuously from the second side surface toward the upper surface and covers the upper surface. The liquid crystal optical element according to claim 1.

7. The substrate is transparent. The liquid crystal optical element according to claim 6.

8. The aforementioned fixing member is opaque, Each of the first liquid crystal film and the second liquid crystal film is configured to reflect a portion of the light incident on the substrate. The liquid crystal optical element according to claim 7.

9. The aforementioned fixing member is transparent. The liquid crystal optical element according to claim 6.

10. The substrate is opaque, Each of the first liquid crystal film and the second liquid crystal film is configured to reflect a portion of the light incident on it through the fixing member. The liquid crystal optical element according to claim 9.

11. No alignment film is interposed between the substrate and the first liquid crystal film, and no adhesive layer is interposed between the first liquid crystal film and the second liquid crystal film. The liquid crystal optical element according to claim 1.

12. The fixing member is in contact with the side surface of the substrate. The liquid crystal optical element according to claim 6.

13. Furthermore, the device includes an alignment film disposed between the substrate and the first liquid crystal film, The fixing member is in contact with the side surface of the orientation film. The liquid crystal optical element according to claim 6.

14. The fixing member is made of a resin material. The liquid crystal optical element according to claim 1.

15. The aforementioned fixing member is made of a silicon compound. The liquid crystal optical element according to claim 1.

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