Birefringent film, method for manufacturing birefringent film, and display device

Abstract

A birefringent film, a manufacturing method for a birefringent film, and a display device are provided. The birefringent film includes a plurality of birefringent layers including liquid crystal polymers of mixed orientation, wherein the plurality of birefringent layers are stacked in a state where orientation directions of the liquid crystal polymers are the same and rising directions of tilt angles of the liquid crystal polymers are the same.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Japanese Patent Application No. 2021-73966, filed on April 26, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to a birefringent film, a method for manufacturing a birefringent film, and a display device. Background Technology

[0004] In related technologies, there are display devices that improve resolution by optically shifting the pixels of a display element. For example, unexamined Japanese Patent Application Publication No. 2007-199726 describes an image display device comprising: a display element having a display surface formed by arranging a plurality of pixels; an image display control device that causes the display element to display different images in a continuous field; and a vibration device that vibrates the optical axis of light emitted from the display surface in a predetermined direction in synchronization with the image switching performed by the image display control device. The vibration device includes a twisted nematic (TN) shutter and a birefringent plate.

[0005] In the case of an image display device according to unexamined Japanese Patent Application Publication No. 2007-199726, a TN shutter alters the polarization direction of light from a pixel and allows light from the pixel to pass through a birefringent plate as either non-ordinary or ordinary light. Additionally, the birefringent plate causes the exit positions of the non-ordinary light and the ordinary light to be offset. When light from a pixel passes through the birefringent plate as non-ordinary light, the pixel's position is observed to be offset from its original position in the display element by half a pixel pitch. However, when light from a pixel passes through the birefringent plate as ordinary light, the pixel's position is observed at its original position in the display element. This configuration increases the resolution of the image display device.

[0006] In unexamined Japanese patent application publication number 2007-199726, examples of materials such as quartz and lithium niobate as birefringent plates are given. Quartz, lithium niobate, etc. have low refractive index anisotropy, and therefore, the thickness of the birefringent plate (birefringent film) must be made very thick in order to offset the position of the pixel by half a pixel pitch.

[0007] In view of the above, this disclosure is made, and the purpose of this disclosure is to provide a thin birefringent film that can offset the emission position of non-ordinary light and the emission position of ordinary light, a method for manufacturing the birefringent film, and a display device. Summary of the Invention

[0008] To achieve the above objective, a birefringent film according to a first aspect of the present invention comprises:

[0009] Multiple birefringent layers, the multiple birefringent layers comprising a mixed-oriented liquid crystal polymer, wherein

[0010] Multiple birefringent layers are stacked with the liquid crystal polymer having the same orientation direction and the same upward direction of the tilt angle.

[0011] According to the second aspect, a birefringent film includes:

[0012] A third birefringent layer, comprising a mixed-oriented liquid crystal polymer, wherein the orientation of the liquid crystal polymer is a predetermined first direction; and

[0013] A fourth birefringent layer comprising a mixed-oriented liquid crystal polymer, wherein the orientation of the liquid crystal polymer is a predetermined second direction intersecting a predetermined first direction at 90°, wherein...

[0014] Stack the third and fourth birefringent layers.

[0015] A method for manufacturing a birefringent film according to the third aspect includes:

[0016] First coating step: Applying a composition containing a polymerizable liquid crystal compound onto an alignment film of an alignment-treated substrate;

[0017] Birefringence layer formation steps: A birefringence layer comprising a liquid crystal polymer with mixed orientations is formed by polymerizing a polymerizable liquid crystal compound to fix the orientation of the polymerizable liquid crystal compound;

[0018] Stripping steps: Stripping the birefringent layer from the substrate; and

[0019] First stacking step: Stack the stripped birefringent layer with the liquid crystal polymers having the same orientation direction and the same upward direction of the tilt angle.

[0020] A method for manufacturing a birefringent film according to the fourth aspect includes:

[0021] First coating step: Applying a composition containing a polymerizable liquid crystal compound onto an alignment film of an alignment-treated substrate;

[0022] Birefringence layer formation steps: A birefringence layer comprising a liquid crystal polymer with mixed orientations is formed by polymerizing a polymerizable liquid crystal compound to fix the orientation of the polymerizable liquid crystal compound;

[0023] Stripping steps: Stripping the birefringent layer from the substrate; and

[0024] The second stacking step involves stacking the stripped birefringent layer in a state where the orientation direction of the liquid crystal polymer is a predetermined first direction and in a state where the orientation direction of the liquid crystal polymer is a predetermined second direction that intersects the predetermined first direction at 90°.

[0025] A method for manufacturing a birefringent film according to the fifth aspect includes:

[0026] First coating step: Applying a composition containing a polymerizable liquid crystal compound onto an alignment film of an alignment-treated substrate;

[0027] Birefringence layer formation steps: A birefringence layer comprising a liquid crystal polymer with mixed orientations is formed by polymerizing a polymerizable liquid crystal compound to fix the orientation of the polymerizable liquid crystal compound;

[0028] Protective layer formation steps: A protective layer is formed on the birefringent layer;

[0029] Alignment film formation steps: forming an alignment film on the protective layer in the same direction as the alignment film on the substrate; and

[0030] The second coating step involves coating a composition containing a polymerizable liquid crystal compound onto an alignment film formed on a protective layer, wherein...

[0031] The process involves repeating the protective layer formation step, the alignment film formation step, the second coating step, and the birefringent layer formation step.

[0032] According to the sixth aspect, a display device includes:

[0033] The birefringent film described above;

[0034] A display panel, comprising a plurality of arranged pixels, wherein a birefringent film is disposed on the display surface side of the display panel; and

[0035] A polarization switching element is disposed between a display panel and a birefringent film. This element switches the light emitted from the display panel between first linearly polarized light with a predetermined polarization direction and second linearly polarized light with a polarization direction orthogonal to the first linearly polarized light, and projects the light onto the birefringent film.

[0036] The polarization switching element emits one of the first linearly polarized light and the second linearly polarized light as ordinary light onto the birefringent film, and emits the other of the first linearly polarized light and the second linearly polarized light as non-ordinary light onto the birefringent film.

[0037] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and do not limit this disclosure.

[0038] According to this disclosure, the stack includes a birefringent layer comprising a liquid crystal polymer having a large refractive anisotropy, thereby reducing the thickness of the birefringent film. Attached Figure Description

[0039] A more complete understanding of this application can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which:

[0040] Figure 1 This is a schematic diagram showing a cross-section of the birefringent film according to Example 1;

[0041] Figure 2 This is a schematic diagram of the first birefringent layer according to Example 1, viewed from above;

[0042] Figure 3 yes Figure 2 The cross-sectional view of the first birefringent layer taken along line AA is shown in the figure;

[0043] Figure 4 This is a schematic diagram used to explain the effect of the birefringent film according to Example 1;

[0044] Figure 5 This is a schematic diagram used to explain the effect of the birefringent film according to Example 1;

[0045] Figure 6 It is a graph showing the dependence of the angle of refraction of nonordinary light on the angle of nonordinary optical axis in the first birefringent layer according to Embodiment 1, and the dependence of the angle of refraction of nonordinary light on the angle of nonordinary optical axis in a birefringent plate made of quartz.

[0046] Figure 7 This is a flowchart illustrating a method for manufacturing a birefringent film according to Example 1;

[0047] Figure 8 This is a schematic diagram used to explain the first application step according to Example 1;

[0048] Figure 9 This is a schematic diagram used to explain the peeling steps according to Example 1;

[0049] Figure 10 This is a schematic diagram showing a cross-section of the birefringent film according to Example 2;

[0050] Figure 11 This is a flowchart illustrating a method for manufacturing a birefringent film according to Example 2;

[0051] Figure 12 This is a schematic diagram used to explain the protective layer formation steps according to Example 2;

[0052] Figure 13This is a schematic diagram used to explain the alignment film formation steps according to Example 2;

[0053] Figure 14 This is a schematic diagram used to explain the second application step according to Example 2;

[0054] Figure 15 This is a schematic diagram showing a cross-section of the birefringent film according to Example 3;

[0055] Figure 16 This is a schematic diagram of the second birefringent layer according to Example 3, viewed from above;

[0056] Figure 17 yes Figure 16 The cross-sectional view of the second birefringent layer along line BB is shown in the figure;

[0057] Figure 18 This is a schematic diagram used to explain the stacking of the first birefringent layer and the second birefringent layer according to Embodiment 3;

[0058] Figure 19 This is a schematic diagram used to explain the first stacking step according to Embodiment 3;

[0059] Figure 20 This is a schematic diagram used to explain the first stacking step according to Embodiment 3;

[0060] Figure 21 This is a schematic diagram used to explain the first stacking step according to Embodiment 3;

[0061] Figure 22 This is a schematic diagram showing a cross-section of the birefringent film according to Example 4;

[0062] Figure 23 This is a schematic diagram showing a cross-section of the fourth birefringent layer according to Example 4;

[0063] Figure 24 This is a schematic diagram used to explain the effect of the birefringent film according to Example 4;

[0064] Figure 25 This is a top view used to explain the effect of the birefringent film according to Example 4;

[0065] Figure 26 This is a flowchart illustrating a method for manufacturing the birefringent film according to Example 4;

[0066] Figure 27 This is a schematic diagram illustrating a display device according to Embodiment 5;

[0067] Figure 28 This is a plan view showing the display panel according to Embodiment 5;

[0068] Figure 29 This is a schematic diagram illustrating the optical offset of pixels according to Embodiment 5;

[0069] Figure 30 This is a schematic diagram showing a cross-section of a birefringent film according to a modified example;

[0070] Figure 31 This is a schematic diagram showing a cross-section of a birefringent film according to a modified example;

[0071] Figure 32 This is a schematic diagram showing a cross-section of the fourth birefringent layer according to a modified example;

[0072] Figure 33 This is a schematic diagram showing a cross-section of a birefringent film according to a modified example;

[0073] Figure 34 This is a schematic diagram illustrating a display device based on a modified example;

[0074] Figure 35 This is a floor plan showing the display panel according to the modified example; and

[0075] Figure 36 This is a schematic diagram showing the optical offset of pixels according to a modified example. Detailed Implementation

[0076] In the following description, birefringent films and display devices according to various embodiments are described with reference to the accompanying drawings.

[0077] Example 1

[0078] Reference Figures 1 to 7 The birefringent film 100 according to this embodiment is described. For example... Figure 1 As shown, the birefringent film 100 includes a first main surface 100a on which light enters and a second main surface 100b on a side opposite to the first main surface 100a. Light entering from the first main surface 100a exits from the second main surface 100b. The birefringent film 100 includes a plurality of first birefringent layers 10 and an adhesive layer 20. The birefringent film 100 is formed by stacking a plurality of first birefringent layers 10 with the adhesive layer 20 disposed therebetween. Figure 1 As shown, in the birefringent film 100 of this embodiment, m first birefringent layers 10 are stacked (where m is a natural number of 2 or greater, for example, m = 40 to 400). In this specification, for ease of understanding, a description is given in which... Figure 1In the birefringent film 100, the right direction (the right direction on the paper) is called the "+X direction," the upward direction (the upward direction on the paper) is called the "+Z direction," and the direction perpendicular to the +X and +Z directions (the depth direction on the paper) is called the "+Y direction." Additionally, for ease of understanding, Figure 1 The shadow of the birefringent layer is omitted. Additionally, for ease of understanding, the shadow of the birefringent layer is sometimes omitted in the accompanying figures below.

[0079] The first birefringent layer 10 includes a first main surface 10a into which light enters and a second main surface 10b on a side opposite to the first main surface 10a. Light entering from the first main surface 10a exits from the second main surface 10b. The first birefringent layer 10 is formed of a mixed-oriented liquid crystal polymer. In one example, the thickness D of the first birefringent layer 10 ranges from 0.5 μm to 3 μm.

[0080] In this context, the term "liquid crystal polymer" refers to a polymer material (polymer) formed by orienting a polymerizable liquid crystal compound 12 (i.e., a liquid crystal compound including polymerizable groups) and then polymerizing the polymerizable liquid crystal compound 12. Additionally, the phrase "orientation direction of the liquid crystal polymer" refers to the direction within the first main surface 10a of the image 14 obtained by projecting a non-ordinary optical axis De of the polymerizable liquid crystal compound 12, which has been oriented and formed into a liquid crystal polymer, onto the first main surface 10a of the first birefringent layer 10. The phrase "tilt angle of the liquid crystal polymer" refers to the direction within the first main surface 10a of the image 14. "" refers to the slope of the non-ordinary optical axis De of the polymerizable liquid crystal compound 12, which is oriented relative to the first main surface 10a of the first birefringent layer 10 and forms a liquid crystal polymer.

[0081] The term "mixed orientation" refers to the slope (i.e., the tilt angle of the liquid crystal polymer) of the polymerizable liquid crystal compound 12 relative to the first main surface 10a of the first birefringent layer 10. ) Continuously changing orientation. Note that in this embodiment, an example is given in which the polymerizable liquid crystal compound 12 is described as a rod-shaped polymerizable liquid crystal compound forming a nematic layer.

[0082] like Figure 2 and Figure 3 As shown, the liquid crystal polymer of the first birefringent layer 10 is oriented in the X direction. Additionally, the tilt angle of the liquid crystal polymer... The tilt angle of the liquid crystal polymer increases in the +Z direction relative to the first main surface 10a (+X direction) and continuously increases from the first main surface 10a toward the second main surface 10b. In one example, the tilt angle of the liquid crystal polymer... From 2° to 70°. Note that the ordinary optical axis Do of the polymerizable liquid crystal compound 12 is parallel to the Y direction.

[0083] like Figure 1As shown, the birefringent film 100 is formed by the liquid crystal polymers having the same orientation and the liquid crystal polymers having a tilt angle of [missing information]. The first birefringent layer 10 is formed by stacking the layers in the same upward direction. Specifically, in the first birefringent layer 10 that is stacked to form the birefringent film 100, the liquid crystal polymer is oriented in the X direction, and the tilt angle of the liquid crystal polymer is... It rises in the +Z direction relative to the first main surface 10a (+X direction). Additionally, in this embodiment, the tilt angle of the liquid crystal polymer... The birefringence increases continuously from the first primary surface 10a of the first birefringence layer 10 toward the second primary surface 10b of the first birefringence layer 10.

[0084] An adhesive layer 20 is positioned between the first birefringent layers 10 and bonds a second main surface 10b of one first birefringent layer 10 to a first main surface 10a of the other first birefringent layer 10. The adhesive layer 20 is a thermosetting adhesive, an ultraviolet (UV) curable adhesive, etc.

[0085] Next, the effects of the birefringent film 100 will be described. In the first birefringent layer 10, the tilt angle of the liquid crystal polymer... (The non-ordinary optical axis De of the polymerizable liquid crystal compound) changes continuously relative to the first main surface 10a (in the + X direction), and thus, Figure 4 The non-ordinary optical axis FDe of the first birefringent layer 10 shown can generally be considered as the tilt angle of the tilted liquid crystal polymer relative to the first main surface 10a (+X direction). average Meanwhile, the ordinary optical axis of the first birefringent layer 10 is generally parallel to the first principal surface 10a (Y direction). Note that, in the following text, the non-ordinary optical axis FDe of the first birefringent layer 10 is generally referred to as the non-ordinary optical axis FDe of the first birefringent layer 10. Additionally, the angle of the non-ordinary optical axis FDe of the first birefringent layer 10 relative to the first principal surface 10a (+X direction) is referred to as... Furthermore, the general optical axis of the first birefringent layer 10 is generally referred to as the general optical axis of the first birefringent layer 10.

[0086] In this embodiment, the tilt angle of the non-ordinary optical axis FDe of the first birefringent layer 10 relative to the +X direction is... And thus, such as Figure 4As shown, when non-ordinary light enters the first principal surface 100a of the birefringent film 100 perpendicularly (parallel to the Z direction), the exit position of the non-ordinary light on the second principal surface 100b of the birefringent film 100 is shifted in the +X direction by an amount corresponding to the distance L1 from the incident position on the first principal surface 100a. However, when ordinary light enters perpendicularly to the first principal surface 100a of the birefringent film 100, the ordinary light enters the birefringent film 100 directly. Therefore, when ordinary light and non-ordinary light enter at the same position P1 on the first principal surface 100a, when viewed from above the second principal surface 100b, as... Figure 5 As shown, ordinary light exits from position P2, which is the same as position P1, and non-ordinary light exits from position P3, which is offset in the +X direction by an amount corresponding to a distance L1 from position P1. Specifically, the birefringent film 100 can offset the exit positions (i.e., positions P2 and P3) of ordinary and non-ordinary light entering at the same position (position P1) on the first main surface 100a from the second main surface 100b by an amount corresponding to a distance L1 in the +X direction. Here, ne is the non-ordinary light refractive index of the liquid crystal polymer, and no is the ordinary light refractive index of the liquid crystal polymer. It is the tilt angle of the liquid crystal polymer relative to the first main surface 10a (X direction). The average value (i.e., the angle of the nonordinary optical axis FDe of the first birefringent layer 10 relative to the first master surface 10a) ), It is the angle of the non-ordinary optical axis FDe of the first birefringent layer 10 relative to the +Z direction. is the angle of refraction of the non-ordinary light (the angle formed between the +Z direction and the refracted non-ordinary light), and D is the thickness of the first birefringent layer 10, with distance L1 represented by the following equations (1) to (3).

[0087]

[0088]

[0089]

[0090] It can be clearly seen from equations (1) to (3) that by increasing the anisotropy of the refractive index... This can increase the refraction angle of non-ordinary light. Furthermore, the thickness of the birefringent film 100 required to achieve distance L1 can be reduced. This is because the first birefringent layer 10 comprises components with a large refractive index anisotropy. (For example, The liquid crystal polymer of polymerizable liquid crystal compound 12 (up to 0.30) is formed, so the thickness of the birefringent film 100 formed by stacking the first birefringent layer 10 can be made greater than that of quartz ( ), lithium niobate ( Birefringent plates made from materials such as [material name] are thinner.

[0091] For example, Figure 6 This shows the angle of refraction of non-ordinary light in the first birefringent layer 10. Angle of non-ordinary optical axis FDe (Refractive index anisotropy of polymerizable liquid crystal compound 12) The dependence on 0.15), and the birefringence of a quartz-based birefringent plate ( The angle of refraction of non-ordinary light Angles of non-ordinary optical axes A graph showing the dependence of (the angle of the non-ordinary optical axis relative to the +X direction). These dependencies are obtained from equations (2) and (3). Figure 6 As shown, compared to a birefringent plate made of quartz, a birefringent plate with a larger refractive index anisotropy... In the first birefringent layer 10 formed by the polymerizable liquid crystal compound 12, the refraction angle of non-ordinary light It can be increased even further. In other words, the thickness of the birefringent film 100 required to obtain distance L1 can be reduced.

[0092] like Figure 6 As shown, the angle of refraction of non-ordinary light Angle relative to the non-ordinary optical axis FDe It has a maximum value. Therefore, preferably, the first birefringent layer 10 is mixed-oriented, thereby having a refraction angle that allows non-ordinary light to be refracted. Maximize the angle of the non-ordinary optical axis FDe (i.e., the tilt angle of the liquid crystal polymer) average Using this configuration, the thickness of the birefringent film 100 can be minimized.

[0093] Next, refer to Figures 7 to 9 The manufacturing method for the birefringent film 100 is also described. Figure 7 This is a flowchart illustrating a method for manufacturing a birefringent film 100; the method for manufacturing a birefringent film 100 includes: a first coating step: coating a composition 36 containing a polymerizable liquid crystal compound 12 onto an alignment film 34a of a substrate 30 that has undergone alignment treatment (step S100); a birefringent layer forming step: forming a birefringent layer 10 comprising a liquid crystal polymer with mixed orientations by polymerizing the polymerizable liquid crystal compound 12 to fix the orientation of the polymerizable liquid crystal compound 12 (step S110); a peeling step: peeling the birefringent layer 10 from the substrate 30 (step S120); and a first stacking step: stacking the liquid crystal polymers in the same orientation direction and with different tilt angles. The stripped birefringent layer 10 is stacked in the same upward direction (step S130).

[0094] In step S100, as Figure 8 As shown, a composition 36 comprising a polymerizable liquid crystal compound 12 is applied to an alignment film 34a of a substrate 30. In one example, a dispenser is used to apply the composition 36 to the alignment film 34a.

[0095] Substrate 30 includes a resin film 32 and an alignment film 34a. The alignment film 34a undergoes an alignment treatment (e.g., a friction treatment) to align the polymerizable liquid crystal compound 12 in the X direction. In one example, the resin film 32 is formed of acrylic resin. In another example, the alignment film 34a is formed of polyimide. Composition 36 includes the polymerizable liquid crystal compound 12, a UV polymerization initiator, etc. Composition 36 may include various types of polymerizable liquid crystal compounds 12, and may also include non-polymerizable liquid crystal compounds, monomers that do not have liquid crystal properties, etc. In this embodiment, the polymerizable liquid crystal compound 12 contained in composition 36 is in contact with air and the alignment film 34a that has undergone the X-direction alignment treatment. The polymerizable liquid crystal compound 12 has the characteristic of being oriented perpendicular to the air interface. Therefore, on the interface side of the alignment film 34a, the polymerizable liquid crystal compound 12 is oriented at a near-horizontal angle relative to the surface of the alignment film 34a, and continuously rises relative to the surface of the alignment film 34a toward the air interface side. That is, the polymerizable liquid crystal compound 12 is mixed-oriented.

[0096] In step S110, the composition 36 coated on the alignment film 34a is irradiated with UV light to polymerize the polymerizable liquid crystal compound 12 and fix the mixed orientation of the polymerizable liquid crystal compound 12. As a result, a first birefringent layer 10 comprising the mixed-oriented liquid crystal polymer is formed on the alignment film 34a.

[0097] In step S120, firstly, the substrate 30 is fixed to the surface plate 40 using an adhesive. Then, for example, as... Figure 9 As shown, a peeling roller 42 with an adhesive layer on its surface is pressed against the formed first birefringent layer 10 to wind the first birefringent layer 10 onto the peeling roller 42, thereby peeling the first birefringent layer 10 off the substrate 30.

[0098] In step S130, a UV-curable adhesive is applied to the second main surface 10b of the first birefringent layer 10, and m layers of the first birefringent layer 10 are stacked with the liquid crystal polymers aligned in the same orientation direction and with the same upward direction of the tilt angle θe. Then, the stacked m layers of the first birefringent layer 10 are pressed in the thickness direction, and the UV-curable adhesive is cured. Thus, a birefringent film 100 can be manufactured.

[0099] As described above, in the birefringent film 100, the first birefringent layer 10 is stacked with the liquid crystal polymers having the same orientation direction and the same upward direction of the tilt angle. Since the first birefringent layer 10 comprises components with large refractive index anisotropy... The liquid crystal polymer of polymerizable liquid crystal compound 12 is formed, so the thickness of the birefringent film 100 can be made thinner than that of a birefringent plate made of quartz, lithium niobate, etc. The birefringent film 100 can offset the exit position of ordinary light and non-ordinary light entering at the same position on the first main surface 100a from the second main surface 100b by an amount corresponding to a distance L1 in the +X direction.

[0100] Example 2

[0101] In the birefringent film 100 of Embodiment 1, the first birefringent layer 10 is stacked such that an adhesive layer 20 is disposed therebetween. Instead of the adhesive layer 20, the birefringent film 100 may include a configuration of a protective layer 46 and an alignment film 34b.

[0102] like Figure 10 As shown, the birefringent film 100 of this embodiment includes a plurality of first birefringent layers 10, a protective layer 46, and an alignment film 34b. The plurality of first birefringent layers 10 are stacked, with the protective layer 46 and the alignment film 34b disposed therebetween. Other configurations of the birefringent film 100 of this embodiment are the same as those of the birefringent film 100 of Embodiment 1, and thus, the protective layer 46 and the alignment film 34b will be described.

[0103] A protective layer 46 is disposed on the second main surface 10b of the first birefringent layer 10. The protective layer 46 protects the first birefringent layer 10 from the solvent in the alignment film 34b. In one example, the protective layer 46 is an acrylic resin layer.

[0104] In this embodiment, the alignment film 34b is formed on the protective layer 46. Similar to the alignment film 34a of Embodiment 1, the alignment film 34b of this embodiment aligns the polymerizable liquid crystal compound 12 in the X direction.

[0105] Next, refer to Figures 10 to 12 The manufacturing method of the birefringent film 100 used in this embodiment is also described. Figure 11This is a flowchart illustrating a method for manufacturing a birefringent film 100 according to this embodiment. The method for manufacturing a birefringent film 100 according to this embodiment includes: a first coating step: coating a composition 36 containing a polymerizable liquid crystal compound 12 onto an alignment film 34a of a substrate 30 that has undergone an alignment treatment (step S100); and a birefringent layer forming step: forming a birefringent layer 10 comprising a liquid crystal polymer with mixed orientation by polymerizing the polymerizable liquid crystal compound 12 to fix the orientation of the polymerizable liquid crystal compound 12 (step S110). The manufacturing method for the birefringent film 100 in this embodiment further includes: a step of determining whether m layers of the first birefringent layer 10 are stacked (step S200); a protective layer forming step: forming a protective layer 46 on the first birefringent layer 10 (step S210); an alignment film forming step: forming an alignment film 34b on the protective layer 46 in the same direction as the alignment film 34a of the substrate 30 (step S220); and a second coating step: coating a composition 36 including a polymerizable liquid crystal compound 12 onto the alignment film 34b formed on the protective layer 46 (step S230). In this embodiment, steps S210 to S230 and step S110 are repeated.

[0106] The first coating step (step S100) and the birefringence layer formation step (step S110) of this embodiment are the same as the first coating step (step S100) and the birefringence layer formation step (step S110) of Embodiment 1.

[0107] In this embodiment, steps S100 and S110 are first performed, and a first birefringent layer 10 is formed.

[0108] In step S200, firstly, the number of times step S110 has been executed is counted. When the number of times step S110 has been executed is less than m, it is determined that m layers of the first birefringent layer 10 have not been stacked (Step S200: No). When it is determined that m layers have not been stacked, the manufacturing process of step S210 is executed, and the second and subsequent layers of the first birefringent layer 10 are stacked. When the number of times step S110 has been executed is m, it is determined that m layers of the first birefringent layer 10 have been stacked, and the manufacturing process ends.

[0109] In step S210, UV-curable acrylic resin is applied onto the formed first birefringent layer 10. Next, as... Figure 12 As shown, UV-curable acrylic resin is irradiated with UV light to form a protective layer 46 on the first birefringent layer 10.

[0110] In step S220, an alignment film 34b is applied to the protective layer 46, and the applied alignment film 34b is baked to remove the solvent from the alignment film 34b. Next, the alignment film 34b on the protective layer 46 undergoes alignment treatment in the same direction (i.e., the X direction) as the alignment film 34a on the substrate 30. As a result, as... Figure 13 As shown, an orientation film 34b that has undergone orientation treatment is formed on the protective layer 46.

[0111] In step S230, the composition 36 is applied onto the alignment film 34b formed on the protective layer 46 using the same method as in step S100. Since the alignment film 34b formed on the protective layer 46 undergoes the same alignment treatment as the alignment film 34a of the substrate 30, the polymerizable liquid crystal compound 12 contained in the composition 36 is oriented in the same way as the first layer of the first birefringent layer 10, such as... Figure 14 As shown. Therefore, by polymerizing the polymerizable liquid crystal compound 12 in step S110, the liquid crystal polymers are aligned in the same direction and the tilt angle of the liquid crystal polymers is... The first birefringent layer 10 is stacked in the same upward direction. After step S230, the manufacturing process of step S110 is performed.

[0112] Therefore, the birefringent film 100 of this embodiment can be manufactured. Note that after stacking m layers of the first birefringent layer 10, the birefringent film 100 can be peeled off from the substrate 30.

[0113] In this embodiment, it is not necessary to peel the first birefringent layer 10 from the substrate 30 each time it is formed. Therefore, the birefringent film 100 can be easily manufactured using fewer steps. In this embodiment, as in Embodiment 1, since the first birefringent layer 10 comprises components with large refractive index anisotropy... The liquid crystal polymer of polymerizable liquid crystal compound 12 is formed, so the thickness of the birefringent film 100 can be made thinner than that of a birefringent plate made of quartz, lithium niobate, etc. Additionally, the birefringent film 100 of this embodiment can deflect ordinary light and non-ordinary light entering at the same position on the first main surface 100a from the exit position of the second main surface 100b by an amount corresponding to a distance L1 in the +X direction.

[0114] Example 3

[0115] The birefringent film 100 of Examples 1 and 2 is formed by stacking a plurality of first birefringent layers 10. It is possible to form the birefringent film 100 by stacking first birefringent layers 10 and second birefringent layers 50.

[0116] The birefringent film 100 in this embodiment includes a first birefringent layer 10, an adhesive layer 20, and a second birefringent layer 50. For example... Figure 15As shown, the birefringent film 100 in this embodiment is formed by alternately stacking a first birefringent layer 10 and a second birefringent layer 50, in which an adhesive layer 20 is disposed. A total of m layers of the first birefringent layer 10 and the second birefringent layer 50 are stacked. The first birefringent layer 10 and The second birefringent layer (50).

[0117] The first birefringent layer 10 in this embodiment is the same as the first birefringent layer 10 in Embodiment 1, and thus, the second birefringent layer 50 and the stacking of the first birefringent layer 10 and the second birefringent layer 50 are described.

[0118] like Figure 15 As shown, the second birefringent layer 50 includes a first main surface 50a into which light enters and a second main surface 50b on a side opposite to the first main surface 50a. Light entering from the first main surface 50a exits from the second main surface 50b. Like the first birefringent layer 10, the second birefringent layer 50 is formed of a mixed-oriented liquid crystal polymer. In this embodiment, the thickness D of the second birefringent layer 50 is the same as the thickness D of the first birefringent layer 10. Additionally, the second birefringent layer 50 and the first birefringent layer 10 are formed of the same composition 36.

[0119] like Figure 16 and Figure 17 As shown, similar to the first birefringent layer 10, the liquid crystal polymer of the second birefringent layer 50 is oriented in the X direction, and the tilt angle of the liquid crystal polymer is... It rises in the +Z direction relative to the +X direction. Simultaneously, the tilt angle of the liquid crystal polymer... The second birefringent layer 50 decreases continuously from the first primary surface 50a toward the second primary surface 50b. When viewed in cross-section on the XZ plane, the second birefringent layer 50 corresponds to the layer obtained by point-symmetrically moving the first birefringent layer 10. Therefore, the tilt angle of the liquid crystal polymer in the second birefringent layer 50... average The tilt angle of the liquid crystal polymer in the first birefringent layer 10 is equal to the tilt angle of the liquid crystal polymer. average .

[0120] In this embodiment, as Figure 15 As shown, the first birefringent layer 10 and the second birefringent layer 50 are aligned in the same direction as the liquid crystal polymer, and the tilt angle of the liquid crystal polymer is the same. The layers are stacked alternately in the same upward direction, similar to the first birefringent layer 10 in Example 1. Additionally, the tilt angle of the liquid crystal polymer in the first birefringent layer 10... The average value θ and the tilt angle of the liquid crystal polymer in the second birefringent layer 50 average They are equal. Therefore, similar to the birefringent film 100 of Embodiment 1, the birefringent film 100 of this embodiment can deflect ordinary light and non-ordinary light entering at the same position on the first main surface 100a from the exit position on the second main surface 100b by an amount corresponding to a distance L1. Furthermore, due to the tilt angle of the liquid crystal polymer near the second main surface 10b of the first birefringent layer 10 and the first main surface 50a of the second birefringent layer 50... The value is related to the tilt angle of the liquid crystal polymer near the second main surface 50b of the second birefringent layer 50 and the first main surface 10a of the first birefringent layer 10 (which are bonded to each other by the adhesive layer 20). The values ​​are basically equal, so incident light scattering that occurs between layers can be suppressed.

[0121] Next, refer to Figures 18 to 21 Simultaneously, a method for manufacturing the birefringent film 100 used in this embodiment is described. The birefringent film 100 of this embodiment can be manufactured by folding the first birefringent layer 10 so that the orientation direction of the liquid crystal polymer matches the X direction. Similar to the manufacturing method of Embodiment 1, the manufacturing method for the birefringent film 100 in this embodiment includes a first coating step (step S100), a birefringent layer formation step (step S110), a peeling step (step S120), and a first stacking step (S130). In this embodiment, by performing steps S100 to S120, a sheet-like first birefringent layer 10 is formed and peeled from the substrate 30. Since steps S100 to S120 of this embodiment are the same as steps S100 to S120 of Embodiment 1, the first stacking step (step S130) of this embodiment is described.

[0122] In step S130, a sheet-like first birefringent layer 10 peeled from the substrate 30 is folded so that the orientation direction of the liquid crystal polymer matches the X direction, and the first main surface 10a and the folded first main surface 10a, or the second main surface 10b and the folded second main surface 10b, are bonded to each other. Figure 18 As shown, since the second birefringent layer 50 corresponds to the layer obtained by point-symmetrically moving the first birefringent layer 10, the orientation direction of the liquid crystal polymer can be matched with the X direction by folding the sheet-like first birefringent layer 10. This allows the liquid crystal polymer to have the same orientation direction and the tilt angle of the liquid crystal polymer to be the same. The first birefringent layer 10 and the second birefringent layer 50 are stacked alternately in the same upward direction.

[0123] Specifically, firstly, such as Figure 19As shown, adhesive 62 is applied to the upper surface (second main surface 10b) of the edge of the sheet-like first birefringent layer 10 disposed on the surface plate 40. Adhesive 62 with a width corresponding to the length of the birefringent film 100 in the X direction is applied. Then, as... Figure 20 As shown, the first birefringent layer 10 is folded onto the adhesive 62 such that the orientation direction of the liquid crystal polymer matches the X direction. As a result, the second main surface 10b and the folded second main surface 10b are bonded to each other via the adhesive 62. Next, the adhesive 62 is applied to the upper surface (first main surface 10a) of the first birefringent layer 10, and as shown... Figure 21 As shown, the first birefringent layer 10 is folded in the opposite direction to the previous fold. As a result, the first main surface 10a and the folded first main surface 10a are bonded to each other via adhesive 62. By repeating the application of adhesive 62 and the folding of the first birefringent layer 10 as described above, the orientation direction of the liquid crystal polymer can be the same and the tilt angle of the liquid crystal polymer can be... The first birefringent layer 10 and the second birefringent layer 50 are stacked alternately in the same upward direction.

[0124] After pressing the stacked first birefringent layer 10 and second birefringent layer 50 in the thickness direction and curing the adhesive 62, excess curved portions are removed. Thus, the birefringent film 100 of this embodiment can be manufactured.

[0125] As described above, the birefringent film 100 of this embodiment uses liquid crystal polymers with the same orientation direction and the same tilt angle. The liquid crystal polymers are alternately stacked in the same upward direction, with the tilt angle of the stacked polymers being... The tilt angle of the continuously increasing first birefringent layer 10 and the liquid crystal polymer therein The second birefringent layer 50 is formed by continuously decreasing in size. The first birefringent layer 10 and the second birefringent layer 50 are stacked by folding a sheet-like first birefringent layer 10 to match the orientation direction of the liquid crystal polymer. Therefore, the birefringent film 100 of this embodiment can be easily manufactured with fewer steps.

[0126] Similar to Example 1, in this embodiment, the thickness of the birefringent film 100 can be made thinner than that of a birefringent plate made of quartz, lithium niobate, etc. Furthermore, like the birefringent film 100 of Example 1, the birefringent film 100 of this embodiment can deflect ordinary light and non-ordinary light entering at the same position on the first main surface 100a from the exit position of the second main surface 100b by an amount corresponding to a distance L1 in the +X direction.

[0127] Example 4

[0128] In Examples 1 to 3, the first birefringent layer 10 or the first birefringent layer 10 and the second birefringent layer 50 are stacked with the liquid crystal polymers having the same orientation direction. It is also possible to stack the birefringent layers with the liquid crystal polymers' orientation directions intersecting at 90°.

[0129] The birefringent film 100 in this embodiment includes a third birefringent layer 70, an adhesive layer 20, and a fourth birefringent layer 80. For example... Figure 22 As shown, the birefringent film 100 of this embodiment is formed by alternately stacking a third birefringent layer 70 and a fourth birefringent layer 80, in which an adhesive layer 20 is disposed. In this embodiment, the liquid crystal polymer of the third birefringent layer 70 is oriented in a predetermined first direction (X direction), and the liquid crystal polymer of the fourth birefringent layer 80 is oriented in a predetermined second direction (Y direction) that intersects the predetermined first direction at 90°. A total of m layers of the third birefringent layer 70 and the fourth birefringent layer 80 are stacked. The third birefringent layer 70 and The adhesive layer 20 in this embodiment is the same as the adhesive layer 20 in Example 1, and the third birefringent layer 70 and the fourth birefringent layer 80 are described therefrom.

[0130] The third birefringent layer 70 has the same configuration as the first birefringent layer 10 in Example 1. Specifically, the liquid crystal polymer of the third birefringent layer 70 is oriented in the X direction (a predetermined first direction). Additionally, the tilt angle of the liquid crystal polymer... It rises in the +Z direction relative to the +X direction and increases continuously from the first main surface 70a toward the second main surface 70b.

[0131] The fourth birefringent layer 80 includes a first main surface 80a into which light enters and a second main surface 80b on a side opposite to the first main surface 80a. Light entering from the first main surface 80a exits from the second main surface 80b. Similar to the first birefringent layer 10 of Embodiment 1, the fourth birefringent layer 80 is formed of a mixed-oriented liquid crystal polymer. In this embodiment, the thickness D of the fourth birefringent layer 80 is the same as the thickness D of the third birefringent layer 70.

[0132] like Figure 22 and Figure 23 As shown, the liquid crystal polymer of the fourth birefringent layer 80 is oriented in the Y direction (a predetermined second direction). Additionally, the tilt angle of the liquid crystal polymer... The gradient increases relative to the -Y direction in the +Z direction, and continuously increases from the first main surface 80a toward the second main surface 80b. Note the tilt angle of the liquid crystal polymer in the third birefringent layer 70. average The tilt angle of the liquid crystal polymer in the fourth birefringent layer 80 average They are equal.

[0133] Next, the effects of the birefringent film 100 in this embodiment will be described.

[0134] In the third birefringent layer 70, similar to the first birefringent layer 10 in Example 1, the non-ordinary optical axis FDe of the third birefringent layer 70 can generally be considered as the tilt angle of the liquid crystal polymer relative to the +X direction. average The ordinary optical axis of the third birefringent layer 70 is generally parallel to the Y direction. Meanwhile, in the fourth birefringent layer 80, the non-ordinary optical axis FDe of the third birefringent layer 70 can generally be considered as the average value of the tilt angle θe of the liquid crystal polymer tilted relative to the -Y direction. The general optical axis of the fourth birefringent layer 80 is generally parallel to the X-direction.

[0135] Therefore, when linearly polarized light PL1 with polarization direction X enters perpendicularly into the first main surface 100a of the birefringent film 100 in this embodiment, the linearly polarized light PL1 is refracted by the third birefringent layer 70, but not by the fourth birefringent layer 80, as shown below. Figure 24 As shown. Moreover, the exit position of the linearly polarized light PL1 with the polarization direction in the X direction on the second main surface 100b is offset in the +X direction by an amount corresponding to the distance L2 from the entry position on the first main surface 100a. Here, the distance L2 is represented by the following equation (4) and the above equations (2) and (3).

[0136]

[0137] Simultaneously, when linearly polarized light PL2 with a polarization direction of Y enters perpendicularly into the first main surface 100a of the birefringent film 100 in this embodiment, the linearly polarized light PL2 is refracted by the fourth birefringent layer 80, but not by the third birefringent layer 70. Moreover, the exit position of the linearly polarized light PL2 with a polarization direction of +Y on the second main surface 100b is offset in the -Y direction by an amount corresponding to a distance L2 from the entry position on the first main surface 100a.

[0138] As described above, the exit position of linearly polarized light PL1, with polarization direction X, is offset by a distance L2 in the +X direction. Simultaneously, the exit position of linearly polarized light PL2, with polarization direction Y, is offset by a distance L2 in the -Y direction. Therefore, when linearly polarized light PL1 and linearly polarized light PL2 enter at the same position P4 on the first main surface 100a, when viewed from above the second main surface 100b, as... Figure 25As shown, linearly polarized light PL1 is emitted from position P5, which is offset in the +X direction by an amount corresponding to a distance L2 from position P4, and linearly polarized light PL2 is emitted from position P6, which is offset in the -Y direction by an amount corresponding to a distance L2 from position P4. In this embodiment, since the number of layers in the third birefringent layer 70 and the fourth birefringent layer 80 is equal, the birefringent film 100 in this embodiment can offset the emission positions of linearly polarized light PL1 and linearly polarized light PL2 (specifically, positions P5 and P6) from the second main surface 100b by a distance L3 represented by the following equation (5).

[0139]

[0140] Next, a method for manufacturing the birefringent film 100 used in this embodiment will be described. Figure 26 This is a flowchart illustrating a method for manufacturing a birefringent film 100 according to this embodiment. The method for manufacturing the birefringent film 100 includes a first coating step (step S100), a birefringent layer formation step (step S110), a peeling step (step S120), and a second stacking step: stacking the peeled third birefringent layer 70 in a state where the orientation direction of the liquid crystal polymer is a predetermined first direction and in a state where the orientation direction of the liquid crystal polymer is a predetermined second direction intersecting the predetermined first direction at 90° (step S300). In this embodiment, the third birefringent layer 70 peeled from the substrate 30 is formed by performing steps S100 to S120. Since steps S100 to S120 of this embodiment are the same as steps S100 to S120 of Embodiment 1, the second stacking step (step S300) of this embodiment will be described.

[0141] Step S300 includes: setting a third birefringent layer 70 such that the orientation direction of the liquid crystal polymer matches the X direction (a predetermined first direction) (step S305); stacking the third birefringent layer 70, whose orientation direction matches the Y direction (a predetermined second direction), as a fourth birefringent layer 80 on the third birefringent layer 70 using a UV-curable adhesive (step S310); determining whether a total of m layers of the third birefringent layer 70 and the fourth birefringent layer 80 have been stacked (step S320); stacking the third birefringent layer 70, whose orientation direction matches the X direction, on the third birefringent layer 70 (i.e., the fourth birefringent layer 80), whose orientation direction matches the Y direction, using a UV-curable adhesive (step S330); and curing the UV-curable adhesive (step S340).

[0142] In step S305, a third birefringent layer 70 is set in the first layer (m = 1) so that the orientation direction of the liquid crystal polymer matches the X direction.

[0143] In step S310, firstly, a UV-curable adhesive is applied to the second main surface 70b of the third birefringent layer 70. Next, the third birefringent layer 70, whose orientation direction matches the Y direction of the liquid crystal polymer, is stacked as a fourth birefringent layer 80 on the applied UV-curable adhesive.

[0144] In step S320, firstly, the number of times step S310 has been executed is counted. When the number of times step S310 has been executed is less than m / 2, it is determined that a total of m layers of the third birefringent layer 70 and the fourth birefringent layer 80 have not been stacked (Step S320: No). When it is determined that a total of m layers have not been stacked, the manufacturing process of step S330 is executed, and the third birefringent layer 70 is stacked. When the number of times step S310 has been executed is m / 2, it is determined that a total of m layers of the third birefringent layer 70 and the fourth birefringent layer 80 have been stacked (Step S320: Yes). When it is determined that a total of m layers have been stacked, the manufacturing process of step S340 is executed, and the UV-curable adhesive is cured.

[0145] In step S330, a UV-curable adhesive is applied to a third birefringent layer 70 (fourth birefringent layer 80) whose orientation direction matches the Y direction of the liquid crystal polymer. Next, the third birefringent layer 70, whose orientation direction matches the X direction of the liquid crystal polymer, is stacked on top of the applied UV-curable adhesive. After step S330, the manufacturing process of step S310 is performed.

[0146] In step S340, the third birefringent layer 70 and the fourth birefringent layer 80, which are stacked in total of m layers, are pressed in the thickness direction, and a UV-curable adhesive is also cured. Therefore, the birefringent film 100 of this embodiment can be manufactured.

[0147] As described above, in the birefringent film 100 of this embodiment, a third birefringent layer 70 oriented in the X direction (a predetermined first direction) and a fourth birefringent layer 80 oriented in the Y direction (a predetermined second direction) of the liquid crystal polymer are alternately stacked. Since the third birefringent layer 70 and the fourth birefringent layer 80 are composed of materials with a large refractive index anisotropy... The liquid crystal polymer of polymerizable liquid crystal compound 12 is formed, so the thickness of the birefringent film 100 in this embodiment can be made thinner than that of a birefringent plate made of quartz, lithium niobate, etc. Additionally, the birefringent film 100 in this embodiment can offset the exit positions of linearly polarized light PL1 (polarization direction X) and linearly polarized light PL2 (polarization direction Y) by an amount corresponding to a distance L3.

[0148] Example 5

[0149] In this embodiment, a display device 300 including the birefringent film 100 of Embodiment 1 is described. For example... Figure 27 As shown, the display device 300 includes a display panel 400, a polarization switching element 500, and a birefringent film 100 as described in Embodiment 1. In this embodiment, the observer is positioned on the +Z side of the display device 300. The 45° direction bisects the X and Y directions corresponds to the observer's left-right direction, and the direction orthogonal to the 45° direction bisects the X and Y directions corresponds to the observer's up-down direction.

[0150] In one example, the display panel 400 is implemented as a transmissive twisted nematic (TN) liquid crystal display driven by a thin-film transistor (TFT) active matrix and equipped with a backlight. Figure 28 As shown, the display panel 400 includes a plurality of pixels 410 arranged at a pixel pitch p. When the display device 300 is viewed from above, the plurality of pixels 410 are arranged in a 45° direction bisecting the X and Y directions, and in a direction orthogonal to the 45° direction bisecting the X and Y directions. Pixel 410 includes a sub-pixel SR that emits red light, a sub-pixel SG that emits green light, and a sub-pixel SB that emits blue light.

[0151] The display panel 400 emits first linearly polarized light with a polarization direction of Y (a predetermined third direction) as display light for displaying images, text, etc. The display light emitted from the display panel 400 enters the polarization switching element 500.

[0152] In one example, the polarization switching element 500 is implemented as a TN liquid crystal element with a twist angle of 90°. The polarization switching element 500 is disposed between the display panel 400 and the birefringent film 100 of Embodiment 1. The polarization switching element 500 switches the display light (i.e., the first linearly polarized light) from the display panel 400 between a first linearly polarized light and a second linearly polarized light. Here, the polarization direction of the second linearly polarized light is the X direction, which is orthogonal to the polarization direction (Y direction) of the first linearly polarized light. Moreover, the polarization switching element 500 emits the display light onto the first main surface 100a of the birefringent film 100 of Embodiment 1. The first linearly polarized light with the Y direction corresponds to ordinary light on the birefringent film 100 of Embodiment 1. At the same time, the second linearly polarized light with the X direction corresponds to non-ordinary light on the birefringent film 100 of Embodiment 1.

[0153] As described in Embodiment 1, the birefringent film 100 of Embodiment 1 can offset the exit position of ordinary light and non-ordinary light entering the first main surface 100a from the second main surface 100b by an amount corresponding to a distance L1 in the +X direction. Therefore, when the light entering the birefringent film 100 from the polarization switching element 500 is first linearly polarized light and when the light entering the birefringent film 100 from the polarization switching element 500 is second linearly polarized light, the distance L1 and the pixel pitch p of the display panel 400 satisfy the following equation (6) so that the position of the pixel 410 is optically offset by an amount corresponding to p / 2 in the left-right direction (the direction bisects the X and Y directions at 45°), and optically offset by an amount corresponding to p / 2 in the up-down direction (the direction orthogonal to the direction bisects the X and Y directions at 45°).

[0154]

[0155] In this embodiment, the display light from the display panel 400 is switched in a time-division manner between first linearly polarized light and second linearly polarized light by the polarization switching element 500. When the display light from the display panel 400 is first linearly polarized light, the first linearly polarized light corresponds to ordinary light on the birefringent film 100 of Embodiment 1, and thus, the observer identifies the position of pixel 410 as the position on the display panel 400. However, when the display light from the display panel 400 is second linearly polarized light, the second linearly polarized light corresponds to non-ordinary light on the birefringent film 100 of Embodiment 1, and thus, the observer identifies the position of pixel 410 as a position offset from the position on the display panel 400 by an amount corresponding to p / 2 in the left-right direction (the direction bisects the X and Y directions at 45°) and by an amount corresponding to p / 2 in the up-down direction (the direction orthogonal to the direction bisects the X and Y directions at 45°), such as... Figure 29 As shown.

[0156] In this embodiment, the polarization switching element 500 switches the display light from the display panel 400 to first linearly polarized light and second linearly polarized light in a time-division manner, synchronously with the timing of the switching. The image corresponding to the position of pixel 410 identified by the observer is displayed on the display panel 400 in a time-division manner. As a result, the display device 300 can display the image with enhanced resolution.

[0157] As described above, the display device 300 can display images with enhanced resolution. Additionally, the birefringent film 100 of Embodiment 1 is thinner, and thus, the thickness of the display device 300 can be reduced.

[0158] Modify Example

[0159] Embodiments have been described, but various modifications may be made to this disclosure without departing from the spirit and scope thereof.

[0160] For example, the polymerizable liquid crystal compound 12 is not limited to rod-shaped polymerizable liquid crystal compounds that form nematic layers. It is possible for the polymerizable liquid crystal compound 12 to be configured as a polymerizable disk-shaped liquid crystal.

[0161] The substrate 30 of this embodiment includes a resin film 32 and an alignment film 34a, but it is possible for the substrate 30 to include a release layer between the resin film 32 and the alignment film 34a. In one example, the release film is formed of silicon material. When the substrate 30 includes a release layer between the resin film 32 and the alignment film 34a, the first birefringent layer 10 of Embodiment 1 is peeled off together with the alignment film 34a.

[0162] In embodiment 3, the first birefringent layer 10 and the second birefringent layer 50 are stacked alternately, but any stacking order of the first birefringent layer 10 and the second birefringent layer 50 can be implemented. For example, as Figure 30 As shown, where Each layer of the second birefringent layer 50 is stacked on top of... The configuration on the first birefringent layer 10 is possible. Additionally, as... Figure 31 As shown, it is possible to alternately stack a first layer group 10A containing multiple first birefringent layers 10 and a second layer group 50A containing multiple second birefringent layers 50. The number of first birefringent layers 10 and the number of second birefringent layers 50 can be different.

[0163] It is possible that the polymerizable liquid crystal compound 12 forming the first birefringent layer 10 and the polymerizable liquid crystal compound 12 forming the second birefringent layer 50 have different configurations.

[0164] In Example 4, the tilt angle θe of the liquid crystal polymer in the fourth birefringent layer 80 continuously increases from the first main surface 80a toward the second main surface 80b. For example... Figure 32 As shown, it is possible to configure the tilt angle θe of the liquid crystal polymer in the fourth birefringent layer 80 to decrease continuously from the first main surface 80a toward the second main surface 80b. Additionally, any stacking order can be used for the third birefringent layer 70 and the fourth birefringent layer 80. For example, as... Figure 33 As shown, where The third birefringent layer 70 is stacked in a layer. The configuration on the fourth birefringent layer 80 is possible. In addition, the number of layers of the third birefringent layer 70 and the fourth birefringent layer 80 can be different. For example, when the birefringent film 100 is formed by the third birefringent layer 70 with the number of layers m1 and the fourth birefringent layer 80 with the number of layers m2 (where m1 and m2 are natural numbers 1 or greater), the birefringent film 100 can offset the linearly polarized light PL1 and linearly polarized light PL2 from the exit position of the second principal surface 100b by a distance L4 represented by the following equation (7).

[0165]

[0166] It is possible that the polymerizable liquid crystal compound 12 forming the third birefringent layer 70 and the polymerizable liquid crystal compound 12 forming the fourth birefringent layer 80 have different configurations.

[0167] Instead of the birefringent film 100 of Embodiment 1, the display device 300 may include the configuration of the birefringent film 100 of Embodiments 2 to 4. For example, as Figure 34 As shown, it is possible for the display device 300 to include the configuration of the display panel 400, polarization switching element 500, and birefringent film 100 of embodiment 4. In this case, a plurality of pixels 410 of the display panel 400 are arranged in the X and Y directions, as shown. Figure 35 As shown. Additionally, the X direction corresponds to the observer's left-right direction, and the Y direction corresponds to the observer's up-down direction. For example... Figure 36 As shown, when the light entering the birefringent film 100 from the polarization switching element 500 is first linearly polarized light and when the light entering the birefringent film 100 from the polarization switching element 500 is second linearly polarized light, the distance L3 and the pixel pitch p of the display panel 400 satisfy the following equation (8) so that the position optical offset of the pixel 410 in the left-right direction of the observer corresponds to The amount, and the optical offset in the vertical direction of the observer corresponds to That amount is sufficient.

[0168]

[0169] When the display device 300 includes the birefringent film 100 of Embodiment 2 or Embodiment 3, the display panel 400, the polarization switching element 500, and the birefringent film 100 of Embodiment 2 or Embodiment 3 are arranged in the same manner as in Embodiment 5. Additionally, when the light entering the birefringent film 100 from the polarization switching element 500 is first linearly polarized light and when the light entering the birefringent film 100 from the polarization switching element 500 is second linearly polarized light, the following equation (6) is satisfied as in Embodiment 5 so that the positional optical offset of the pixel 410 corresponds to the left-right direction (45° direction bisecting the X and Y directions) of the observer. The quantity, and the optical offset in the observer's vertical direction (orthogonal to the 45° direction bisecting the X and Y directions) corresponds to That amount is sufficient.

[0170] It is possible for the display panel 400 of the display device 300 to be configured as an organic electroluminescence (EL) display panel. Note that when the display panel 400 is configured as an organic EL display panel, the polarization switching element 500 includes a polarizing plate on the display panel 400 side.

[0171] For illustrative purposes, some exemplary embodiments have been described above. Although specific embodiments have been presented in the foregoing discussion, those skilled in the art will recognize that changes in form and detail may be made without departing from the broader spirit and scope of the invention. Therefore, the specification and drawings are to be viewed in an illustrative rather than restrictive sense. Consequently, this detailed description should not be construed in a restrictive sense, and the scope of the invention is defined only by the included claims and the full scope of their equivalents.

Claims

1. A display device, comprising: Birefringent film; A display panel, including a plurality of arranged pixels, wherein the birefringent film is disposed on the display surface side of the display panel; as well as A polarization switching element is disposed between the display panel and the birefringent film. It switches the light emitted from the display panel between first linearly polarized light with a predetermined polarization direction and second linearly polarized light with a polarization direction orthogonal to the polarization direction of the first linearly polarized light, and projects the light onto the birefringent film. The birefringent film comprises multiple birefringent layers, each comprising a mixed-alignment liquid crystal polymer. Each of the plurality of birefringent layers has a first principal surface for light incident and a second principal surface for light exit. The plurality of birefringent layers are stacked such that the first principal surface of one of the birefringent layers and the second principal surface of another of the birefringent layers face each other. The plurality of birefringent layers are stacked in such a manner that in each of the plurality of birefringent layers, the liquid crystal polymer has the same orientation direction, and when viewed in cross-section over a cross-section including the orientation direction, the non-ordinary optical axis of the liquid crystal polymer has the same tilt direction relative to the first main surface. The polarization switching element emits one of the first linearly polarized light and the second linearly polarized light as ordinary light onto the birefringent film, and emits the other of the first linearly polarized light and the second linearly polarized light as non-ordinary light onto the birefringent film. In the birefringent film, the exit position of non-ordinary light incident from the polarization switching element is offset from the exit position of ordinary light incident from the polarization switching element.

2. The display device according to claim 1, wherein... The pixel comprises multiple sub-pixels that emit light of different colors, and When p is the pixel pitch, ne is the non-ordinary optical refractive index of the liquid crystal polymer, no is the ordinary optical refractive index of the liquid crystal polymer, θ is the average tilt angle of the liquid crystal polymer, D is the thickness of the birefringent layer contained in the birefringent film, m is the number of birefringent layers contained in the birefringent film, L1 is the distance from the incident position, α is the angle of the non-ordinary optical axis of the birefringent layer, and β is the refraction angle of the non-ordinary light, the following conditions are met: and 。 3. The display device according to claim 1 or 2, wherein, The birefringent film also includes a protective layer between the birefringent layers.

4. The display device according to claim 1 or 3, wherein, The plurality of birefringent layers includes a first birefringent layer and a second birefringent layer. In the first birefringent layer, when viewed in cross-section, the tilt angle of the non-ordinary optical axis of the liquid crystal polymer continuously increases from the first main surface toward the second main surface. In the second birefringent layer, when viewed in cross-section, the tilt angle of the non-ordinary optical axis of the liquid crystal polymer continuously decreases from the first main surface toward the second main surface. The first birefringent layer and the second birefringent layer are stacked in such a state that when viewed in cross-section, the non-ordinary optical axis of the liquid crystal polymer is tilted in the same direction relative to the first main surface.

5. The display device according to claim 4, wherein, The first birefringent layer and the second birefringent layer are stacked alternately.

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