Pressure-sensitive film and tactile sensor system

Abstract

Provided is a pressure-sensitive film and a tactile sensor system having a high spatial resolution. This pressure-sensitive film contains a first base material and a second base material. The first base material includes a support body and a partition wall disposed on the support body. The partition wall divides a space between the support body and the second base material into a plurality of regions. The plurality of regions obtained by said division contain at least an oriented liquid crystal compound.

Description

Pressure-sensitive film and tactile sensor system

[0001] The present invention relates to a pressure-sensitive film and a tactile sensor system.

[0002] Pressure sensors are used in various fields. For example, in applications such as tactile sensing (tactile detection) in the robotics industry and input interfaces, the requirements for pressure sensors are increasing. Specifically, in robotic applications, it is desired to detect pressure, contact area, etc. so that a robot can apply an appropriate force according to the shape, hardness, etc. when grasping something.

[0003] Such pressure sensors are desired to be thinned, and as a thin pressure sensor, a pressure-sensitive film using a liquid crystal compound has been proposed. A pressure-sensitive film using a liquid crystal compound seals a liquid crystal compound oriented in a predetermined orientation state between two substrates, and when an external force is applied to the pressure-sensitive film, it detects a change in the optical characteristics of the pressure-sensitive film caused by the disturbance of the orientation state of the liquid crystal compound to detect pressure.

[0004] For example, Patent Document 1 describes a pressure sensor that has an alignment means for aligning a ferroelectric liquid crystal on at least one of the substrates between substrates parallel to each other, aligns a ferroelectric liquid crystal showing at least an isotropic and chiral smectic C phase state, changes the alignment of the ferroelectric liquid crystal by the pressure applied to the substrate, and optically detects the change in the alignment using a polarizing plate.

[0005] Japanese Patent Laid-Open No. 05-196527

[0006] According to the study by the present inventors, it has been found that a pressure-sensitive film using a liquid crystal material has a problem that when an external pressure is applied, not only in the region where the external pressure is applied but also in the region where the external pressure is not applied, the alignment state of the liquid crystal compound is disturbed and the optical characteristics change. That is, it has been found that a conventional pressure-sensitive film using a liquid crystal material has a problem of low spatial resolution.

[0007] An object of the present invention is to provide a pressure-sensitive film and a tactile sensor system with high spatial resolution.

[0008] As a result of diligent research by the inventors into addressing the above problem, they found that the above problem can be solved by the following configuration.

[0009] [1] A pressure-sensitive film comprising a first substrate and a second substrate, wherein the first substrate comprises a support and a partition disposed on the support, the partition divides the space between the support and the second substrate into a plurality of regions, and at least oriented liquid crystal compounds are contained within the plurality of divided regions. [2] The pressure-sensitive film according to [1], wherein the first substrate further comprises a polarizer, or the support is a polarizer. [3] The pressure-sensitive film according to [1], wherein the second substrate comprises a polarizer. [4] The pressure-sensitive film according to [2], wherein the second substrate comprises a polarizer. [5] The pressure-sensitive film according to any one of [1] to [4], wherein at least one of the first substrate and the second substrate further comprises an alignment film for aligning the liquid crystal compounds. [6] The pressure-sensitive film according to any one of [1] to [5], wherein the liquid crystal compounds are vertically oriented. [7] The pressure-sensitive film according to any one of [1] to [6], wherein the peel force between the first substrate and the second substrate is 0.5 N / 25 mm or more. [8] A pressure-sensitive film according to any one of [1] to [7], wherein the thickness of the partition wall is 0.005 mm to 2 mm, the height of the partition wall is 0.001 mm to 0.1 mm, and the tensile modulus of elasticity of the partition wall is 100 MPa to 6000 MPa. [9] A pressure-sensitive film according to any one of [1] to [8], wherein the first substrate further includes a transparent deformation layer, or the support is a transparent deformation layer, the Shore OO hardness of the transparent deformation layer is 5 to 60, and the thickness of the transparent deformation layer is 0.1 mm to 10 mm.

[10] A pressure-sensitive film according to any one of [1] to [9], wherein the second substrate further includes a transparent deformation layer, the Shore OO hardness of the transparent deformation layer is 5 to 60, and the thickness of the transparent deformation layer is 0.1 mm to 10 mm.

[11] A tactile sensor system comprising a pressure-sensitive film according to any one of [1] to

[10] and an imaging unit.

[0010] According to the present invention, it is possible to provide a pressure-sensitive film and a tactile sensor system with high spatial resolution.

[0011] Figure 1 is a conceptual diagram showing an example of the pressure-sensitive film of the present invention. Figure 2 is a top view of the partition wall of the pressure-sensitive film shown in Figure 1. Figure 3 is a top view of another example of the partition wall of the pressure-sensitive film of the present invention. Figure 4 is a diagram for explaining the state of the liquid crystal compound near the partition wall of the pressure-sensitive film shown in Figure 1. Figure 5 is a conceptual diagram for explaining the operation of the pressure-sensitive film shown in Figure 1. Figure 6 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 7 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 8 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 9 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 10 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 11 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 12 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. Figure 13 is a conceptual diagram showing an example of a tactile sensor system having a pressure-sensitive film according to the present invention. Figure 14 is a conceptual diagram showing another example of a tactile sensor system having a pressure-sensitive film according to the present invention.

[0012] The present invention will be described in detail below.

[0013] The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0014] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0015] In this specification, terms such as “same” include a range of error that is generally accepted in the art, for example, a range of ±5%.

[0016] Furthermore, in this specification, parallel, orthogonal, and perpendicular do not mean parallel, orthogonal, and perpendicular in the strict sense, but rather a range of ±5° from parallel, orthogonal, or perpendicular, respectively. The same applies to other angles, which also refer to a range of ±5°.

[0017] In this specification, the "absorption axis" refers to the polarization direction in which the absorbance is maximized when linearly polarized light is incident on the element. The "transmission axis" refers to the direction perpendicular to the absorption axis in the element. Furthermore, the "latent axis" refers to the direction in which the refractive index is maximized in the element.

[0018] Embodiments of the present invention will be described below with reference to the drawings. The following figures are conceptual diagrams illustrating the pressure-sensitive film and tactile sensor system of the present invention. Therefore, the shape, size, thickness, and positional relationships of each component may not necessarily correspond to those of actual components.

[0019] [Pressure-sensitive film] The pressure-sensitive film of the present invention comprises a first substrate and a second substrate, wherein the first substrate comprises a support and a partition wall disposed on the support, the partition wall divides the space between the support and the second substrate into a plurality of regions, and at least an oriented liquid crystal compound is contained within the plurality of divided regions.

[0020] Figure 1 is a conceptual diagram showing an example of the pressure-sensitive film of the present invention.

[0021] The pressure-sensitive film 10a shown in Figure 1 includes a first substrate 12a and a second substrate 14a, and each of the multiple regions U formed between the first substrate 12a and the second substrate 14a has a liquid crystal compound (liquid crystal cell containing the liquid crystal compound). That is, the pressure-sensitive film 10a has a plurality of liquid crystal cells arranged in the planar direction between the first substrate 12a and the second substrate 14a. In the example shown in Figure 1, the first substrate 12a has a first support 16, a partition wall 18, and an alignment film 20. The second substrate 14a has a second support 26 and an alignment film 28.

[0022] The pressure-sensitive film of the present invention detects pressure by detecting a change in optical properties caused by a disturbance in the orientation state of the liquid crystal compounds within the liquid crystal cells arranged between the first substrate 12a and the second substrate 14a when pressure is applied. In this pressure-sensitive film, the liquid crystal cells are divided into multiple sections in the planar direction by partition walls 18. Therefore, when pressure is applied to the pressure-sensitive film, the orientation state of the liquid crystal compounds within the liquid crystal cells corresponding to the pressure-applied position changes, but the partition walls 18 can suppress the propagation of the change in the orientation state of the liquid crystal compounds to the liquid crystal cells corresponding to positions where no pressure is applied, thus enabling more accurate detection of the pressure-applied position. In other words, the pressure-sensitive film of the present invention can achieve high spatial resolution. This point will be described in detail later.

[0023] <First Substrate> The first substrate 12a has a partition wall 18 on the surface of the first support 16 that faces the second substrate 14a, and an orientation film 20 on the surface of the partition wall 18 that is opposite to the first support 16. Therefore, in the example shown in Figure 1, the orientation film 20 is in contact with the second substrate 14a.

[0024] <<First Support>> The first support 16 supports the partition wall 18 and the orientation film 20, etc. The first support 16 can be any type of sheet material (film, plate) as long as it can support the partition wall 18 and the orientation film 20, etc. For industrial continuous production, a long film-like (sheet-like) support can also be used.

[0025] As the first support, a transparent support is preferred, such as a glass plate and a polymer film. Examples of polymer film materials include cellulose polymers; acrylic polymers having acrylic acid ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene polymers; polycarbonate polymers; polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); polyolefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymer; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamides; imide polymers; sulfone polymers; polyethersulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinylidene chloride polymers; vinyl alcohol polymers; vinyl butyral polymers; arylate polymers; polyoxymethylene polymers; epoxy polymers; or polymers obtained by mixing these polymers. The first support is not limited to a flexible film, but may also be a non-flexible support such as a glass plate. Furthermore, the first support may be multilayered, and the multilayered support may be a laminate formed by stacking multiple of the various supports described above.

[0026] There are no restrictions on the thickness of the first support; it can be set appropriately depending on the forming material of the first support, as long as sufficient self-supporting properties and strength can be ensured. The thickness of the first support is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 20 μm to 90 μm.

[0027] Furthermore, as will be described later, a polarizer may be used as the first support.

[0028] <<Partition Wall>> The partition wall 18 is positioned on the first support 16 and divides the space between the first support 16 and the second substrate 14a into multiple regions. The first support 16 and the second substrate 14a are positioned at a predetermined distance apart in a direction perpendicular to their main surfaces, and the partition wall 18 divides the space between the first support 16 and the second substrate 14a into multiple regions. The main surface is the largest surface of the sheet-like material (film-like material, plate-like material).

[0029] Specifically, in the example shown in Figure 1, the partition wall 18 is a single layer provided across the entire main surface of the first support 16 on the second base material 14a side, and has a protrusion (18a) projecting toward the second base material 14a side. This protrusion is the partition wall portion 18a that divides the space between the first support 16 and the second base material 14a into multiple regions U. In the example shown in Figure 1, the cross-sectional shape of the partition wall portion 18a perpendicular to the main surface of the first support 16 (hereinafter also simply referred to as the cross-sectional shape of the partition wall portion) is approximately trapezoidal.

[0030] The partition wall 18 can also be described as a layer having a plurality of recesses discretely formed in the planar direction of the main surface of the first support 16. Each recess corresponds to each region U, and a liquid crystal cell is provided in each recess.

[0031] Figure 2 shows a top view of an example of the partition wall 18 as seen from a direction perpendicular to the main surface of the first support 16. In the example shown in Figure 2, the partition wall portion 18a has a honeycomb structure and divides the space between the first support 16 and the second substrate 14a into a plurality of substantially hexagonal regions U as viewed from a direction perpendicular to the main surface of the first support 16. Therefore, each region U (liquid crystal cell) divided by the partition wall portion 18a is substantially hexagonal truncated. The partition wall portion 18a separates each region U (liquid crystal cell) from each other in the plane direction of the main surface of the first support 16, and they are discretely arranged in two dimensions. In this invention, discrete arrangement means that, as shown in Figure 2, when observed from a direction perpendicular to the main surface of the first support 16, the plurality of regions U are arranged in isolation without contacting each other in the plane direction of the main surface of the first support 16.

[0032] In the example shown in Figure 2, the partition wall 18a has a honeycomb structure, dividing the space between the first support 16 and the second substrate 14a into a plurality of regions U that are approximately hexagonal when viewed from a direction perpendicular to the main surface of the first support 16, but the invention is not limited to this.

[0033] For example, as shown in Figure 3, the partition wall 18a may have a grid-like structure that divides the space between the first support 16 and the second base material 14a into a plurality of substantially square-shaped regions U when viewed from a direction perpendicular to the main surface of the first support 16. Alternatively, the partition wall 18a may have a structure that divides the space between the first support 16 and the second base material 14a such that the shape of the region U (the shape when viewed from a direction perpendicular to the main surface of the first support 16) is any shape such as a circle, an ellipse, a rectangle, a triangle, a pentagon, other polygons, or an irregular shape.

[0034] Furthermore, the shapes of the multiple regions U divided by the partition wall 18a may all be the same shape, or they may include regions of different shapes. For example, the multiple regions U may include a region U that is approximately square-shaped and a region U that is approximately rectangular, or a region U that is approximately hexagonal and a region U that is approximately pentagonal.

[0035] Furthermore, in the example shown in Figure 1, the cross-sectional shape of the partition wall portion 18a is approximately trapezoidal, but it is not limited to this, and may be approximately rectangular, or rectangular or trapezoidal with the corners on the second base material 14a side beveled into a curved surface, or rectangular or trapezoidal with the corners on the first support 16 side beveled into a curved surface. The cross-sectional shape of the partition wall portion 18a is preferably such that at least a part of it widens gradually from the upper end (second base material 14a side) downwards (first support 16 side), preferably from the upper end to the lower end, as shown in Figure 1. Such a shape is advantageous in terms of ease of manufacturing the mold for forming the partition wall 18, ease of removing the mold when forming the partition wall 18, and prevention of damage to the partition wall 18 being formed. Note that in Figure 2, the cross-sectional shape of the partition wall portion 18a is the cross-section along the direction perpendicular to the extending direction of the partition wall portion 18a, that is, the cross-sectional shape along the thickness direction of the partition wall portion 18a.

[0036] The partition wall 18 can be formed, for example, by preparing a composition containing one or more polymerizable compounds, applying it, and curing it. The composition for forming the partition wall 18 may also contain various components such as polymerization initiators, inorganic particles, and light scattering particles. For compositions for forming the partition wall 18 (polymerizable compositions), refer to paragraphs

[0174] to

[0179] of WO2018 / 186300, etc.

[0037] As an example, the partition wall 18 can be formed on the first support 16 by filling a mold having irregularities corresponding to the partition wall portion 18a and recess of the partition wall 18 with a coating liquid (composition) that will become the partition wall 18, stacking a first support 16 so as to cover the coating liquid filled in the mold, curing the coating liquid that will become the partition wall 18, and then removing the mold.

[0038] The method for forming the partition wall 18 is not limited to the method described above, and various known methods for forming a sheet-like material with irregularities can be used. For example, examples include a method in which a composition to be formed as the partition wall 18 is first applied to the first support 16, a mold is pressed onto the composition, and then the composition is cured; a method in which the first support 16 and the mold are laminated together, the composition to be formed as the partition wall 18 is filled between the first support 16 and the mold, and then the composition is cured. In addition to these methods, methods such as forming a planar resin layer and then forming recesses by etching to form the partition wall 18, and methods using printing methods such as inkjet and dispenser methods to form the partition wall 18 can also be used.

[0039] For more detailed methods of forming the partitions, see paragraphs

[0135] to

[0136] of WO2021 / 221080, paragraphs

[0102] to

[0104] of WO2021 / 251448, etc.

[0040] From the viewpoint of ensuring the height of the liquid crystal cells that function appropriately as a pressure-sensitive film, increasing spatial resolution, and increasing the phase difference of the liquid crystal layer, the height h of the partition wall portion 18a (see Figure 1) is preferably 0.001 mm to 0.1 mm, more preferably 0.003 mm to 0.07 mm, and even more preferably 0.01 mm to 0.05 mm.

[0041] From the perspective of increasing the spatial resolution, the thickness t of the partition portion 18a is preferably from 0.005 mm to 2 mm, more preferably from 0.01 mm to 0.5 mm, and even more preferably from 0.02 mm to 0.2 mm. Here, as shown in FIGS. 2 and 3, the thickness t of the partition portion 18a is the thickness in the direction orthogonal to the extending direction of the partition portion 18a when the partition 18 is viewed from a direction perpendicular to the main surface of the first support 16. Also, when the cross-sectional shape of the partition portion 18a is trapezoidal as in the example shown in FIG. 1, or when the thickness of the partition portion 18a changes in the height direction, the thickness at the position of 1 / 2 of the height h of the partition portion 18a is taken as the thickness t of the partition portion 18a.

[0042] When pressure is applied to the pressure-sensitive film, it is necessary to suppress the change in the alignment state of the liquid crystal compound in the liquid crystal cell corresponding to the position where the pressure is applied from propagating to the liquid crystal cell corresponding to the position where no other pressure is applied, that is, from the perspective of increasing the spatial resolution, the partition portion 18a is preferably hard. Specifically, the tensile elastic modulus of the partition 18 (partition portion 18a) is preferably from 100 MPa to 6000 MPa, more preferably from 300 MPa to 5000 MPa, and even more preferably from 500 MPa to 4000 MPa.

[0043] The tensile elastic modulus of the partition 18 (partition portion 18a) can be measured in accordance with JIS K7161.

[0044] Also, the size of the region U when the partition 18 is viewed from a direction perpendicular to the main surface of the first support 16 is not particularly limited, but from the perspectives of increasing the spatial resolution and improving the detection sensitivity for detection, etc., the diameter R of the circumscribed circle circumscribing the region U is preferably from 0.005 mm to 2 mm, more preferably from 0.05 mm to 1.5 mm, and even more preferably from 0.1 mm to 1 mm.

[0045] The size of the region U can be measured from an image obtained by imaging the pressure-sensitive film with an optical microscope (microscope) or the like. As an example, the portion surrounded by the black line in the polarized light optical image is taken as the region U, and it can be measured by obtaining the diameter of the circle circumscribing the region U using the image processing software ImageJ.

[0046] <<Alignment Film>> The alignment film 20 is positioned on the side of the partition wall 18 opposite to the first support 16 side, and aligns the liquid crystal compound 40 in the liquid crystal cell located in region U to a predetermined orientation.

[0047] In the example shown in Figure 1, the orientation film 20 is positioned to completely cover the side of the partition wall 18 that has the partition wall portion 18a. That is, the orientation film 20 is positioned to cover the top and side of the partition wall portion 18a, as well as the bottom surface of the recess.

[0048] As the alignment film, known alignment films such as a thin resin layer with a rubbing treatment on its surface, or a photo-alignment film that exhibits orientation-regulating force in a specific direction by polarized or unpolarized irradiation can be used as appropriate.

[0049] The material and treatment method of the alignment film are not particularly limited, and various alignment films can be used, such as alignment films using polymers, alignment films subjected to silane coupling treatment, alignment films using quaternary ammonium salts, alignment films in which silicon dioxide is deposited obliquely, and alignment films utilizing photoisomerization. Furthermore, surface treatments such as rubbing, energy ray irradiation, and light irradiation may be used as surface treatments for the alignment film.

[0050] The orientation film using the polymer is preferably one of the following: a layer using polyamic acid or polyimide; a layer using modified or unmodified polyvinyl alcohol; a layer using modified or unmodified polyacrylic acid; or a layer using a (meth)acrylic acid copolymer containing any of the repeating units represented by the following general formula (I), the following general formula (II), or the following general formula (III). Note that "(meth)acrylic acid" is a notation that represents acrylic acid or methacrylic acid.

[0051]

[0052] Here, in general formulas (I) to (III), R １ and R ２ Each is independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms; M is a proton, an alkali metal ion, or an ammonium ion; L０ is -O-, -CO-, -NH-, -SO ２ - A divalent linking group selected from the group consisting of alkylene groups, alkenylene groups, arylene groups, and combinations thereof; R ０ m is a hydrocarbon group having 10 to 100 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 100 carbon atoms; Cy is an aliphatic ring group, an aromatic group or a heterocyclic group, and is particularly preferably having a carbazole group; m is 10 to 99 mol%; and n is 1 to 90 mol%.

[0053] Of these, using an orientation layer containing polyimide, a compound represented by general formulas (I) to (III), or a silane coupling agent is preferred from the viewpoint of orientation ability, durability, insulation, and cost, and in particular, it is preferred to use an orientation film containing polyimide and a compound represented by general formulas (I) to (III) and having a carbazole group.

[0054] As the alignment film, as described above, a photo-alignment film that enables liquid crystal alignment treatment by irradiation with polarized and unpolarized ultraviolet (UV) light may also be used. The photo-alignment film can impart alignment restricting force in any direction simply by controlling the polarization axis of the irradiated linearly polarized light. As the material for the photo-alignment film, polymer materials such as photo-alignment polymers having a cinnamoyl structure, polyamide compounds, and polyimide compounds; liquid crystal alignment films formed by liquid crystal alignment agents having photo-aligning groups as described in Japanese Patent Application Publication No. 2012-155308; products such as LPP-JP265CP from Rolic Technologies and JALS2096 from JSR Corporation can be used.

[0055] As described later, it is preferable that the liquid crystal compounds in each liquid crystal cell be vertically oriented. Treatments to make the alignment film function as an alignment film that vertically aligns the liquid crystal compounds include, for example, rubbing treatment, polarized irradiation treatment, and microfabrication treatment. Alternatively, a vertically oriented film can also be formed by applying methods such as gas phase adsorption, immersion, and spin coating using alignment agents such as cetyltrimethylammonium bromide and octadecylethoxysilane.

[0056] The thickness of the orientation film is not particularly limited, but for example, 0.01 to 10 μm is preferred, 0.01 to 1 μm is more preferred, and 0.01 to 0.5 μm is even more preferred.

[0057] <Second Substrate> The second substrate 14a has an orientation film 28 on the surface of the second support 26 that faces the first substrate 12a. Therefore, in the example shown in Figure 1, the orientation film 28 is in contact with the first substrate 12a. As mentioned above, the first substrate 12a has an orientation film 20 on its outermost layer, so in the example shown in Figure 1, the orientation film 20 of the first substrate 12a and the orientation film 28 of the second substrate 14a are in contact.

[0058] <<Second Support>> The second support 26 supports the alignment film 28, etc. The same support as the first support 16 can be used for the second support 26. Alternatively, as will be described later, a polarizer may be used for the second support 26.

[0059] <<Alignment Film>> The alignment film 28 is arranged on the surface of the second support 26 facing the first substrate 12a, and aligns the liquid crystal compound 40 in the liquid crystal cell located in region U to a predetermined orientation. The alignment film 28 can be the same as the alignment film 20.

[0060] <Liquid Crystal Cell> The liquid crystal cell contains a liquid crystal compound 40 and is arranged in each of the multiple regions U divided by a partition wall 18 between the first support 16 of the first substrate 12a and the second substrate 14a.

[0061] In a liquid crystal cell, at least a portion of the liquid crystal compound 40 is oriented in a predetermined orientation. In the example shown in Figure 1, the liquid crystal compound 40 is vertically oriented. However, the orientation of the liquid crystal compound is not limited to this; it may also be horizontally oriented or tilted.

[0062] In this specification, vertical orientation means that the main surface of the first support 16 and the long axis direction of the liquid crystal compound 40 are perpendicular to each other. However, it is not required that they be strictly perpendicular; in this specification, it means that the angle between the long axis direction of the liquid crystal compound 40 and the main surface of the first support 16 is between 80° and 100°. Similarly, horizontal orientation means that the main surface of the first support 16 and the long axis direction of the liquid crystal compound 40 are parallel to each other. However, it is not required that they be strictly parallel; in this specification, it means that the angle between the long axis direction of the liquid crystal compound 40 and the main surface of the first support 16 is less than 10°.

[0063] In the liquid crystal cell, the orientation of the liquid crystal compound 40 is not fixed, and it has fluidity and liquid crystal properties with a regular arrangement. In other words, the liquid crystal cell (composition containing the liquid crystal compound 40) is not cured.

[0064] Here, as shown in Figure 4, in a liquid crystal cell, the orientation of the liquid crystal compound 40 located near the partition wall 18a may be disrupted by the influence of the partition wall 18a, but at positions spaced apart from the partition wall 18a in the planar direction, the liquid crystal compound 40 is properly oriented. Thus, each liquid crystal cell arranged in each region U only needs to have at least a portion of the liquid crystal compound 40 oriented.

[0065] The type of liquid crystal compound 40 is not particularly limited, and either rod-shaped liquid crystal compounds or disc-shaped liquid crystal compounds can be used. In addition, two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or a mixture of rod-shaped and disc-shaped liquid crystal compounds may be used.

[0066] For example, the liquid crystal compound 40 can be Merck's ZLI2806, 5CB, or the like.

[0067] A composition containing a liquid crystal compound 40 for forming a liquid crystal cell (hereinafter also referred to as a liquid crystal cell forming composition) may contain components other than the liquid crystal compound 40. For example, the liquid crystal cell forming composition may contain an orientation control agent, a surfactant, a leveling agent, a solvent, a chiral agent, and the like.

[0068] For example, as described above, when vertically aligning the liquid crystal compound 40, the liquid crystal cell forming composition preferably contains a vertical alignment agent. The vertical alignment agent preferably uses a boronic acid compound and / or an onium salt. Specific examples of vertical alignment agents can be found in Japanese Patent Application Publication No. 2024-103795, etc.

[0069] The method for forming liquid crystal cells is not particularly limited. For example, a first substrate 12a can be manufactured by providing partition walls 18 on a first support 16 (and further forming an alignment film 20 if necessary), then applying a liquid crystal cell forming composition containing a liquid crystal compound to the partition wall 18 side of the first substrate 12a and filling each region U divided by the partition wall 18, and then laminating a second substrate 14a onto the region U (partition wall 18) side of the first substrate 12a that is filled with the liquid crystal cell forming composition by a method such as pressing to produce a pressure-sensitive film.

[0070] The liquid crystal cell formation composition can be applied using known methods (for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, or die coating).

[0071] In each liquid crystal cell, for example, if a liquid crystal compound that forms the nematic phase at room temperature is used, the liquid crystal compound is oriented to the nematic phase according to the orientation-regulating force of the alignment film and / or the action of the orientation control agent.

[0072] <Function of the pressure-sensitive film> Next, the function of the pressure-sensitive film 10a having the above configuration will be explained using Figure 5.

[0073] Figure 5 is a conceptual diagram showing a state in which an external pressure N is applied to a portion of the pressure-sensitive film 10a from the surface on the second substrate 14a side.

[0074] As shown in Figure 5, when an external pressure N is applied to a position corresponding to a certain region U1 on the surface of the pressure-sensitive film 10a on the second substrate 14a side, the liquid crystal compounds 40 of the liquid crystal cells within this region U1 each enter a different state, such as being horizontal or tilted at various angles, and the orientation of the liquid crystal compounds 40 is disrupted. This disruption of the orientation of the liquid crystal compounds 40 propagates not only to the liquid crystal compounds 40 located at the position where the external pressure N is applied, but also to the liquid crystal compounds 40 throughout almost the entire region U1.

[0075] On the other hand, region U1 and region U2 adjacent to region U1 are separated by a partition wall 18. Therefore, the liquid crystal compound 40 of the liquid crystal cell in region U2 does not receive the disruption of the orientation of the liquid crystal compound 40 in region U1 to which the external pressure N is applied, and maintains its original vertical orientation.

[0076] As mentioned above, our inventors' studies have shown that pressure-sensitive films using liquid crystal materials have a problem with low spatial resolution because, when external pressure is applied, the orientation of the liquid crystal compound becomes disordered not only in the area where the external pressure is applied, but also in the area where the external pressure is not applied, causing a change in optical properties.

[0077] In contrast, the pressure-sensitive film of the present invention divides the space between the first support 16 and the second substrate 14a into a plurality of regions U by a partition wall 18, and each region U has liquid crystal cells containing a liquid crystal compound 40. That is, the pressure-sensitive film of the present invention has a plurality of liquid crystal cells divided by the partition wall 18. Therefore, as described above, it is possible to suppress the propagation of the disorder of the orientation of the liquid crystal compound 40 in the liquid crystal cells in the region U1 corresponding to the position where the external pressure N is applied to the liquid crystal compound 40 in the region U corresponding to the position where the external pressure N is not applied. As a result, when detecting pressure by detecting changes in optical properties caused by the disorder of the orientation state of the liquid crystal compound 40 using the pressure-sensitive film, it is possible to more accurately detect the position where the external pressure N is applied and the position where the external pressure N is not applied, and the spatial resolution can be increased.

[0078] Furthermore, conventionally known methods can be appropriately used as methods for detecting changes in the optical properties of a pressure-sensitive film caused by disturbances in the orientation state of the liquid crystal compound 40.

[0079] As an example, by placing a pressure-sensitive film between two linear polarizers arranged with their transmission axes perpendicular to each other (arranged in crossed nicols), and irradiating light from one of the linear polarizers, the light that has passed through the pressure-sensitive film and the other linear polarizer is detected (imaged) by an image sensor, it is possible to detect changes in the optical properties of the pressure-sensitive film at each position in the planar direction.

[0080] More specifically, for example, if the liquid crystal compound 40 in each region U of the pressure-sensitive film is vertically oriented, in region U2 where no external pressure N is applied, linearly polarized light that has passed through one linear polarizer passes through the pressure-sensitive film and enters the other linear polarizer. However, since the polarization direction of this linearly polarized light is perpendicular to the transmission axis of the other linear polarizer, it is shielded, and the image sensor does not detect the light.

[0081] On the other hand, in region U1 where external pressure N is applied, the orientation of the liquid crystal compound 40 is disrupted and becomes close to horizontal orientation, and has an in-plane phase difference. Therefore, when linearly polarized light that has passed through one linear polarizer is incident on the pressure-sensitive film, the polarization state of this linearly polarized light changes due to the influence of the phase difference of the liquid crystal cells. Since the light with the changed polarization state contains a polarization component in a direction parallel to the transmission axis of the other linear polarizer, at least a portion of the light incident on the other linear polarizer is transmitted and detected by the image sensor. In other words, in this detection method, an image is captured in which the position of the pressure-sensitive film where external pressure N is not applied is dark, and the position where external pressure N is applied is bright.

[0082] In the example shown in Figure 5, the external pressure N is assumed to be applied from the second substrate 14a side, but this is not the only option, and the external pressure N may also be applied from the first substrate 12a side.

[0083] Furthermore, although the above description assumes that the two linear polarizers are arranged so that their transmission axes are perpendicular to each other, the explanation is not limited to this, and the two linear polarizers may be arranged so that their transmission axes are perpendicular to each other.

[0084] When two linear polarizers are positioned with their transmission axes parallel to each other, in region U2 where no external pressure N is applied, linearly polarized light that has passed through one linear polarizer passes through the pressure-sensitive film and enters the other linear polarizer, and since it passes through this linear polarizer, the image sensor detects light of high intensity.

[0085] On the other hand, in region U1 where external pressure N is applied, when linearly polarized light that has passed through one linear polarizer is incident on the pressure-sensitive film, the polarization state of this linearly polarized light changes due to the phase difference of the liquid crystal cell. Since the light with the changed polarization state contains a polarization component in a direction perpendicular to the transmission axis of the other linear polarizer, at least a portion of the light incident on the other linear polarizer is blocked, and the amount of light decreases, which is detected by the image sensor. In other words, in this detection method, an image is captured in which the position of the pressure-sensitive film where external pressure N is not applied is bright, and the position where external pressure N is applied is slightly dark.

[0086] Furthermore, although the above explanation described the function of the pressure-sensitive film using the example where the liquid crystal compound 40 is vertically oriented, the optical properties also change when the liquid crystal compound 40 is horizontally oriented and when it is tilted. Therefore, pressure can be detected by detecting the change in optical properties at each position in the planar direction of the pressure-sensitive film.

[0087] It is preferable that the liquid crystal compound 40 is vertically oriented, as this increases the change in optical properties between when external pressure N is applied and when external pressure N is not applied, making it easier to detect changes in optical properties.

[0088] Furthermore, in the example shown in Figure 5, the external pressure N is applied to a range smaller than the size of region U, but this is not limited to this, and the external pressure N may be applied to a larger range spanning multiple regions U. In this case, since the orientation of the liquid crystal compound 40 is disturbed in each of the multiple regions U corresponding to the position where the external pressure N is applied, the pressure can be detected by detecting the change in optical properties. At that time, since the disturbance of the orientation of the liquid crystal compound 40 in region U can be suppressed in the position where the external pressure N is not applied, the position, size, and shape of the range where the external pressure N is applied can be detected more accurately.

[0089] <Other configurations of pressure-sensitive film> In the example shown in Figure 1, the partition wall 18 has a configuration with multiple recesses, but it is not limited to this. As shown in the pressure-sensitive film 10b in Figure 6, the partition wall 18b may have a configuration with multiple through holes instead of recesses. That is, the partition wall 18b has only the portion corresponding to the partition wall portion 18a of the partition wall 18. The pressure-sensitive film 10b shown in Figure 6 has the same configuration as the pressure-sensitive film 10a shown in Figure 1, except that it has a partition wall 18b instead of a partition wall 18.

[0090] In the pressure-sensitive film 10b shown in Figure 6, the alignment film 20 of the first substrate 12b is positioned to cover the top and sides of the partition wall 18b, as well as a portion of the surface of the first support 16 on the second substrate 14a side.

[0091] Furthermore, in the example shown in Figure 1, the first substrate 12a and the second substrate 14a each have an orientation film, but the invention is not limited to this configuration. Either the first substrate 12a or the second substrate 14a may not have an orientation film, or neither the first substrate 12a nor the second substrate 14a may have an orientation film.

[0092] The pressure-sensitive film 10c shown in Figure 7 has a first substrate 12c and a second substrate 14b. The first substrate 12c does not have an alignment film 20, but has a first support 16 and a partition wall 18. The second substrate 14b does not have an alignment film 28, but has a second support 26. The pressure-sensitive film 10c shown in Figure 7 has the same configuration as the pressure-sensitive film 10a shown in Figure 1, except that it does not have an alignment film 20 and an alignment film 28.

[0093] In the case of such a pressure-sensitive film 10c, the partition wall portion 18a of the first substrate 12c and the second support 26 of the second substrate 14b are in contact.

[0094] Furthermore, in cases where neither the first substrate 12c nor the second substrate 14b has an alignment film, such as in the pressure-sensitive film 10c, it is preferable that the liquid crystal cells (liquid crystal cell forming composition) arranged in each region U contain an alignment control agent. In the case of the pressure-sensitive film 10c shown in Figure 7, the liquid crystal cells contain a vertical alignment agent.

[0095] In the pressure-sensitive film of the present invention, the first substrate may further contain a polarizer. Furthermore, the second substrate may further contain a polarizer.

[0096] Figure 8 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. The pressure-sensitive film 10d shown in Figure 8 includes a first substrate 12d and a second substrate 14c, and each of the multiple regions U formed between the first substrate 12d and the second substrate 14c has a liquid crystal compound 40 (liquid crystal cell containing the liquid crystal compound 40). The pressure-sensitive film 10d shown in Figure 8 has the same configuration as the pressure-sensitive film 10a shown in Figure 1, except that the first substrate 12d has a polarizer 22 and the second substrate 14c has a polarizer 30.

[0097] In the pressure-sensitive film 10d, the first substrate 12d includes a first support 16, a partition wall 18 positioned on the second substrate 14c side of the first support 16, an alignment film 20 positioned on the side of the partition wall 18 opposite to the first support 16 side, and a polarizer 22 positioned on the side of the first support 16 opposite to the second substrate 14c side. The second substrate 14c includes a second support 26, an alignment film 28 positioned on the first substrate 12d side of the second support, and a polarizer 30 positioned on the side of the second support 26 opposite to the first substrate 12d side.

[0098] Polarizers 22 and 30 are linear polarizers and may be arranged so that their transmission axes are orthogonal to each other, or so that they are parallel, but it is preferable that their transmission axes are orthogonal to each other.

[0099] With this configuration, the pressure-sensitive film 10d can detect pressure by detecting changes in the optical properties at each position in the planar direction of the pressure-sensitive film using the method described above.

[0100] In the example shown in Figure 8, both the first substrate 12d and the second substrate 14c are configured to have polarizers, but the system is not limited to this configuration, and either the first substrate 12d or the second substrate 14c may be configured to have a polarizer.

[0101] Furthermore, in the pressure-sensitive film 10d shown in Figure 8, the first substrate 12d has a first support 16 and a polarizer 22, and the second substrate 14c has a second support 26 and a polarizer 30, but the invention is not limited to this configuration.

[0102] Figure 9 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. The pressure-sensitive film 10e shown in Figure 9 includes a first substrate 12e and a second substrate 14d, and each of the plurality of regions U formed between the first substrate 12e and the second substrate 14d has a liquid crystal compound 40 (liquid crystal cell containing the liquid crystal compound 40). The pressure-sensitive film 10e shown in Figure 9 has the same configuration as the pressure-sensitive film 10a shown in Figure 1, except that the first substrate 12e has a polarizer 22 instead of a first support 16, and the second substrate 14d has a polarizer 30 instead of a second support 26.

[0103] In the pressure-sensitive film 10e, the first substrate 12e has a polarizer 22, a partition wall 18 positioned on the second substrate 14d side of the polarizer 22, and an alignment film 20 positioned on the opposite side of the partition wall 18 from the polarizer 22 side. The second substrate 14d has a polarizer 30 and an alignment film 28 positioned on the first substrate 12e side of the polarizer 30.

[0104] In such a pressure-sensitive film 10e, the polarizer 22 also functions as a first support, and the polarizer 30 also functions as a second support. In other words, the first support is a polarizer, and the second support is a polarizer.

[0105] <<Polarizer>> The polarizer (22, 30) is not particularly limited and can be any so-called linear polarizer that has the function of converting natural light into a specific linear polarization. The polarizer is not particularly limited and may be an absorptive polarizer or a reflective polarizer. As an absorptive polarizer, for example, any of iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers can be used. As a reflective polarizer, conventionally known linear polarizers such as wire grid polarizers can be used.

[0106] In the present invention, the thickness of the polarizer is not particularly limited, but is preferably 3 μm to 60 μm, more preferably 5 μm to 30 μm, and particularly preferably 5 μm to 15 μm.

[0107] Here, the pressure-sensitive film of the present invention may further have a transparent deformation layer.

[0108] Figure 10 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. The pressure-sensitive film 10f shown in Figure 10 includes a first substrate 12d and a second substrate 14e, and each of the plurality of regions U formed between the first substrate 12d and the second substrate 14e has a liquid crystal compound 40 (liquid crystal cell containing the liquid crystal compound 40). Note that the pressure-sensitive film 10f shown in Figure 10 has the same configuration as the pressure-sensitive film 10d shown in Figure 8, except that it has a second substrate 14e instead of a second substrate 14c.

[0109] The second substrate 14e includes a polarizer 30, an alignment film 28 positioned on the first substrate 12d side of the polarizer 30, and a transparent deformation layer 32 positioned on the first substrate 12d side of the polarizer 30. That is, the second substrate 14e is the same as the second substrate 14d of the pressure-sensitive film 9e shown in Figure 9, except that it further includes the transparent deformation layer 32.

[0110] Figure 11 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. The pressure-sensitive film 10g shown in Figure 11 comprises a first substrate 12d and a second substrate 14f, and each of the plurality of regions U formed between the first substrate 12d and the second substrate 14f has a liquid crystal compound 40 (liquid crystal cell containing the liquid crystal compound 40). The pressure-sensitive film 10g shown in Figure 11 has the same configuration as the pressure-sensitive film 10d shown in Figure 8, except that the second substrate 14f further has a transparent deformation layer 32.

[0111] The second substrate 14f includes a second support 26, an alignment film 28 positioned on the first substrate 12d side of the second support, a polarizer 30 positioned on the side of the second support 26 opposite to the first substrate 12d side, and a transparent deformation layer 32 positioned on the side of the polarizer 30 opposite to the second support 26 side.

[0112] Furthermore, in the examples shown in Figures 10 and 11, the second substrate of the pressure-sensitive film has a transparent deformation layer, but the invention is not limited to this configuration, and the first substrate may also have a transparent deformation layer.

[0113] Figure 12 is a conceptual diagram showing another example of the pressure-sensitive film of the present invention. The pressure-sensitive film 10h shown in Figure 12 includes a first substrate 12f and a second substrate 14c, and each of the multiple regions U formed between the first substrate 12f and the second substrate 14c has a liquid crystal compound 40 (liquid crystal cell containing the liquid crystal compound 40). Note that the pressure-sensitive film 10h shown in Figure 12 has the same configuration as the pressure-sensitive film 10d shown in Figure 8, except that it has a first substrate 12f instead of the first substrate 12d.

[0114] The first substrate 12f includes a polarizer 22, a partition wall 18 positioned on the second substrate 14c side of the polarizer 22, an alignment film 20 positioned on the opposite side of the partition wall 18 from the polarizer 22 side, and a transparent deformation layer 24 positioned on the opposite side of the polarizer 22 from the second substrate 14c side.

[0115] As shown in Figures 10 to 12, the pressure-sensitive films have a transparent deformation layer in the first substrate and / or second substrate. When external pressure is applied, the soft transparent deformation layer deforms, thus providing shape-following capabilities to the object in contact. In other words, it becomes possible to improve the spatial resolution of pressure regardless of the hardness and shape of the object in contact.

[0116] The transparent deformation layer may be provided on only one of the first substrate and the second substrate, or on both. Preferably, the transparent deformation layer is provided on the side to which the external pressure N is applied.

[0117] Furthermore, if the first substrate has a transparent deformation layer, the transparent deformation layer may be positioned at any location on the first substrate, but it is preferable that it be positioned close to the surface opposite to the second substrate. Furthermore, if the second substrate has a transparent deformation layer, the transparent deformation layer may be positioned at any location on the second substrate, but it is preferable that it be positioned close to the surface opposite to the first substrate. Furthermore, if the first substrate has a polarizer and a transparent deformation layer, it is preferable that the transparent deformation layer be positioned close to the surface opposite to the second substrate in order to reduce the effect of the phase difference of the transparent deformation layer. Similarly, if the second substrate has a polarizer and a transparent deformation layer, it is preferable that the transparent deformation layer be positioned close to the surface opposite to the first substrate.

[0118] Furthermore, in the first substrate and / or the second substrate, the transparent deformation layer may also function as a support. That is, the support may be the transparent deformation layer.

[0119] <<Transparent Deformable Layer>> The transparent deformable layer is a layer made of a flexible and elastic material that is optically transparent, deformable in accordance with the external pressure N applied, and returns to its original state when the external pressure N is released. In the present invention, the transparent deformable layer 32 is a layer with a Shore OO hardness value of approximately 5 to 60.

[0120] The transparent deformation layer 32 may be formed from a gel or other relatively flexible material. Suitable materials for the transparent deformation layer include urethane, nitrile, chloroprene, EPDM, silicone resin, and mixtures thereof.

[0121] The transparent deformation layer preferably has a Shore hardness of 5 to 60, more preferably 10 to 50, and even more preferably 15 to 40. Furthermore, the tensile modulus of the transparent deformation layer is preferably lower than that of the partition wall.

[0122] Furthermore, the transparent deformation layer is preferably 0.1 mm to 10 mm thick, more preferably 1 mm to 8 mm thick, and even more preferably 2 mm to 5 mm thick.

[0123] By ensuring that the Shore hardness OO and thickness of the transparent deformation layer meet the above range, the transparent deformation layer at the location where the external pressure N is applied deforms appropriately when the external pressure N is applied, thereby changing the orientation state of the liquid crystal compound 40 of the liquid crystal cell at the location where the external pressure N is applied.

[0124] The Shore OO hardness of the transparent deformation layer can be measured using a Shore OO durometer according to the procedure described in ASTM D2240.

[0125] In the pressure-sensitive film of the present invention, the peeling force between the first substrate and the second substrate is preferably 0.5 N / 25 mm or more, more preferably 0.7 N / 25 mm or more, and even more preferably 1.0 N / 25 mm or more. There is no particular upper limit to the peeling force, but it is preferably 30 N / 25 mm or less, more preferably 25 N / 25 mm or less, and even more preferably 20 N / 25 mm or less.

[0126] By setting the peeling force between the first substrate and the second substrate within the above range, when an external pressure N is applied to the pressure-sensitive film, the first substrate and the second substrate partially peel off, causing adjacent regions U to communicate with each other. This suppresses the propagation of the disorder in the orientation of the liquid crystal compound 40 in the region U where the external force N is applied to the region U where the external force N is not applied.

[0127] The peeling force between the first substrate and the second substrate is measured as follows.

[0128] After cutting the pressure-sensitive film to dimensions of 25 mm in width and 150 mm in length, a 10 mm gap is created between the first and second substrates using a cutter. Next, a glass plate (50 mm in width, 70 mm in length, 1.1 mm in thickness) is bonded to the second substrate side of the pressure-sensitive film using an adhesive (SK1478, manufactured by Soken Chemical Co., Ltd.). Then, using a Tensilon universal tester RTF-2430 (manufactured by A&D Co., Ltd.), the previously peeled portion is chucked, and the load value at the time of peeling between the first and second substrates is measured. The average value of the load in the strain-load curve between 20 and 80 mm is calculated, and the adhesion force (N / 25 mm) is determined.

[0129] In addition, in the measurement of the peeling force described above, the location where peeling occurs is not limited to the interface where the first substrate and the second substrate are in contact, but may also occur between the layers constituting the first substrate or between the layers constituting the second substrate. For example, peeling may occur between the first support and the partition wall of the first substrate, but in this application, regardless of the location where peeling occurs, the peeling force measured by the above measurement method is considered to be the peeling force between the first substrate and the second substrate.

[0130] The pressure-sensitive film of the present invention may further have other functional layers. For example, it may have an adhesive layer, a bonding layer, a protective layer, a light-reflecting layer, a decorative layer, and the like.

[0131] [Tactile Sensor System] The tactile sensor system of the present invention is a tactile sensor system that includes the pressure-sensitive film described above and an imaging unit.

[0132] Furthermore, it is preferable that the tactile sensor system of the present invention further includes an illumination unit.

[0133] Figure 13 is a conceptual diagram showing an example of a tactile sensor system of the present invention having a pressure-sensitive film of the present invention.

[0134] The tactile sensor system 100a shown in Figure 13 comprises a pressure-sensitive film 10, an imaging unit 102, and an illumination unit 104. Note that the liquid crystal compound 40 contained in the pressure-sensitive film 10 is not shown in Figure 13.

[0135] The pressure-sensitive film 10 is the pressure-sensitive film described above, and may be any of the pressure-sensitive films 10a to 10h.

[0136] The illumination unit 104 irradiates light onto the pressure-sensitive film 10. In the example shown in Figure 13, the illumination unit 104 is located on the side of the pressure-sensitive film 10 opposite to the imaging unit 102.

[0137] The lighting unit 104 has a light source that emits light, and may also have optical components such as lenses, linear polarizers, light guide plates, diffusers, optical fibers, etc., that diffuse the light emitted by the light source.

[0138] There are no particular limitations on the light source of the lighting unit 104; various light sources (light-emitting elements) can be used as long as they can emit a predetermined amount of light. Examples of light sources include LEDs (Light Emitting Diodes), LDs (Laser Diodes), and fluorescent lamps. The light source may be a white light source, a light source that emits monochromatic light such as red light, blue light, and green light, or a light source that emits light of multiple colors such as red light and green light. The light source may also be a light source that emits invisible light such as infrared light.

[0139] The imaging unit 102 detects light that has passed through the pressure-sensitive film 10. In the example shown in Figure 13, the imaging unit 102 is located on the side of the pressure-sensitive film 10 opposite to the illumination unit 104.

[0140] The imaging unit 102 has an image sensor for detecting light, and may further have optical members such as lenses for imaging light onto the imaging surface of the image sensor, a linear polarizer, an optical directionality control member (louver film), a protective layer, etc.

[0141] There are no particular limitations on the image sensor of the imaging unit 102. For example, a solid-state image sensor is preferably used, and CCD image sensors, CMOS image sensors, organic thin-film image sensors, and other semiconductor image sensors can be used.

[0142] In the tactile sensor system 100a having this configuration, the illumination unit 104 irradiates light onto the pressure-sensitive film 10, and the imaging unit 102 detects the light transmitted through the pressure-sensitive film 10. As described above, the optical properties of the pressure-sensitive film 10 change at the position where external pressure N is applied, and the amount of transmitted light differs between the position where external pressure N is applied and the position where external pressure N is not applied. Therefore, by imaging the light transmitted through the pressure-sensitive film 10 with the imaging unit 102, the position, size, and shape of the area where external pressure N is applied can be accurately detected.

[0143] Figure 14 is a conceptual diagram showing another example of the tactile sensor system of the present invention, which has a pressure-sensitive film of the present invention.

[0144] The tactile sensor system 100b shown in Figure 14 comprises a pressure-sensitive film 10, an imaging unit 102, an illumination unit 104, and a light-reflecting layer 50. Note that the liquid crystal compound 40 contained in the pressure-sensitive film 10 is not shown in Figure 14.

[0145] The pressure-sensitive film 10 is the pressure-sensitive film described above, and for example, has one of the configurations of pressure-sensitive films 10a to 10h.

[0146] The light-reflecting layer 50 is laminated on the side of the pressure-sensitive film 10 opposite to the imaging section 102. The light-reflecting layer 50 is a layer made of a metal such as silver or aluminum. The light-reflecting layer made of a metal such as silver or aluminum is formed on the surface of the pressure-sensitive film 10 by, for example, vapor deposition. The thickness of the light-reflecting layer is preferably 20 nm to 2000 nm, more preferably 50 nm to 1000 nm, and even more preferably 100 nm to 500 nm.

[0147] The illumination unit 104 irradiates light onto the pressure-sensitive film 10. In the example shown in Figure 14, the illumination unit 104 is positioned on the side of the pressure-sensitive film 10 opposite to the side with the light-reflecting layer 50. The illumination unit 104 has the same configuration as in the example shown in Figure 13, except for its positioning.

[0148] The imaging unit 102 detects light that has passed through the pressure-sensitive film 10. In the example shown in Figure 14, the imaging unit 102 is positioned on the side of the pressure-sensitive film 10 opposite to the light-reflecting layer 50. The imaging unit 102 has the same configuration as in the example shown in Figure 13.

[0149] In the tactile sensor system 100b having this configuration, the illumination unit 104 irradiates the pressure-sensitive film 10 with light, which passes through the pressure-sensitive film 10, is reflected by the light-reflecting layer 50, and the light that passes through the pressure-sensitive film 10 again is detected by the imaging unit 102. As described above, the optical properties of the pressure-sensitive film 10 change at the position where external pressure N is applied, and the amount of transmitted light differs between the position where external pressure N is applied and the position where external pressure N is not applied. Therefore, by imaging the light that has passed through the pressure-sensitive film 10 with the imaging unit 102, the position, size, and shape of the area where external pressure N is applied can be accurately detected.

[0150] Furthermore, in the case of a tactile sensor system 100b having a light-reflecting layer 50, an external pressure N is applied to the pressure-sensitive film 10 via the light-reflecting layer 50. Therefore, the light-reflecting layer 50 is in contact with the pressure-sensitive film 10, and it can also be said that the pressure-sensitive film 10 includes the light-reflecting layer 50.

[0151] Furthermore, if the first substrate and / or second substrate of the pressure-sensitive film 10 do not have a polarizer, it is sufficient to have a polarizer at any position between the light source and the pressure-sensitive film, and / or between the pressure-sensitive film and the image sensor. For example, as described above, the illumination unit may have a polarizer, or the imaging unit may have a polarizer.

[0152] The present invention will be specifically described below based on examples. The materials, reagents, amounts and proportions of substances, and procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the present invention is not limited to the following examples.

[0153] [Example 1] <Preparation of the first substrate> A cellulose acylate film (TAC film, manufactured by Fujifilm Corporation, product name: ZRD40SL) was used as the first support.

[0154] (Preparation of partition-forming composition) The partition-forming composition was prepared by adding the following components to a tank and mixing them.

[0155] ------------------------------------------------------------------- Composition for forming partitions ------------------------------------------------------------------- KAYARAD DPCA30 (manufactured by Nippon Kayaku Co., Ltd.) 99 parts by mass Polymerization initiator Irgacure 819 (manufactured by BASF) 1 part by mass -------------------------------------------------------------------

[0156] (Formation of partition walls) A sheet-like mold (surface material: hard chrome, base material: stainless steel, base material thickness: 0.3 mm) was prepared as a mold for forming partition walls, having protrusions corresponding to the recesses of the partition walls and recesses corresponding to the partition walls. Here, the recesses of the partition walls (protrusions of the mold) were regular hexagonal in shape with sides of 125 μm and had a honeycomb pattern. The height h of the partition wall (depth of the recess in the mold) was set to 30 μm, and the wall thickness t of the partition wall (distance between the protrusions in the mold) was set to 50 μm. The bottom corners of the recesses of the mold that form the partition walls were curved with a radius of curvature of 10 μm.

[0157] The previously prepared partition-forming composition was filled to completely fill the recesses of the mold. Next, the first support was laminated onto the mold so as to completely cover the partition-forming composition, and the partition-forming composition was photocured while being pressed with a laminator at a pressure of 0.5 MPa. The photocuring of the partition-forming composition was performed using a 200 W / cm air-cooled metal halide lamp (manufactured by I-Graphics) with ultraviolet light at a rate of 500 mJ / cm from the first support side. 2 This was done by irradiation. Afterwards, the mold was removed and a partition wall was formed on the first support.

[0158] Furthermore, in order to measure the tensile modulus of the partition wall, a resin film with a thickness of 50 μm was formed using the above-mentioned partition wall forming composition under the same conditions, and the tensile modulus of this resin film was measured in accordance with JIS K7161. The tensile modulus of the partition wall was 4.2 GPa.

[0159] (Preparation of the orientation film coating solution) The orientation film coating solution was prepared using the following formulation.

[0160] ―――――――――――――――――――――――――――――――― Alignment film coating liquid ――――――――――――――――――――――――――――――――――

[0161] (Formation of the alignment film) The alignment film coating solution was applied to the side of the partition wall formed above that was opposite to the first support (the side facing the partition wall) using a bar coater #1.6. Then, it was dried at a film surface temperature of 80°C for 1 minute to form an alignment film and prepare the first substrate. At this time, the film thickness of the alignment film was 60 nm.

[0162] <Preparation of the second substrate> A cellulose acylate film (TAC film, manufactured by Fujifilm Corporation, product name: ZRD40SL) was used as the second support.

[0163] (Formation of alignment film) The alignment film coating solution was applied to one side of the second support using a bar coater #1.6. Then, it was dried at a film surface temperature of 80°C for 1 minute to form an alignment film and prepare the second substrate. At this time, the film thickness of the alignment film was 60 nm.

[0164] <Preparation of pressure-sensitive film> After dropping 1 cc of liquid crystal cell forming composition (ZLI2806 (manufactured by Merck)) onto the alignment film of the first substrate prepared above, the second substrate was laminated onto the first substrate on which the liquid crystal cell forming composition was dropped, with the alignment film side facing outwards, and a pressure-sensitive film was prepared by laminating it with a laminator at a pressure of 0.5 MPa. The liquid crystal compounds in each liquid crystal cell of the prepared pressure-sensitive film are vertically aligned due to the action of the alignment film.

[0165] <Fabrication of a Tactile Sensor System> A tactile sensor system was fabricated by arranging a CMOS sensor, a linear polarizer, a pressure-sensitive film, and another linear polarizer in that order, with each component in contact with the others. An Artray USB 2.0 CMOS miniature camera (ARTCAM-022MINI-BW) was used as the CMOS sensor, and the two polarizers were positioned so that their slow phase axes were perpendicular to each other (so-called crossed nicols). The imaging area of ​​the CMOS sensor was 4.5 mm x 2.9 mm, and the total film thickness of the tactile sensor system was 4.8 mm.

[0166] Furthermore, a linear polarizing plate prepared using the following procedure was used as the linear polarizing plate.

[0167] (Preparation of Linear Polarizer) The surface of a cellulose acylate film support (manufactured by Fujifilm Corporation, product name: ZRD40SL) was subjected to alkali saponification treatment. Specifically, the support was immersed in a 1.5 N sodium hydroxide aqueous solution at 55°C for 2 minutes, then washed in a water bath at room temperature, and further neutralized with 0.1 N sulfuric acid at 30°C. After neutralization, the support was washed in a water bath at room temperature and further dried with hot air at 100°C to obtain a polarizer protective film. A roll of polyvinyl alcohol (PVA) film with a thickness of 60 μm was continuously stretched in the longitudinal direction in an iodine aqueous solution and dried to obtain a polarizer with a thickness of 13 μm. The luminous efficiency correction single transmittance of the polarizer was 43%. At this time, the absorption axis direction and the longitudinal direction of the polarizer coincided. The polarizer protective film was bonded to both sides of the above polarizer using the PVA adhesive described below and dried at 80°C for 2 minutes to prepare a linear polarizer.

[0168] (Preparation of PVA adhesive) A PVA adhesive was prepared by dissolving 100 parts by mass of a polyvinyl alcohol resin having an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) and 20 parts by mass of methylolmelamine in pure water at a temperature of 30°C, and adjusting the solid content concentration to 3.7% by mass as an aqueous solution.

[0169] [Evaluation] (Adhesion) The prepared pressure-sensitive film was cut to dimensions of 25 mm in width and 150 mm in length. Using a cutter, it was partially peeled 10 mm away from the first and second substrates. Next, a glass plate (50 mm in width, 70 mm in length, 1.1 mm in thickness) and the second substrate side of the pressure-sensitive film were bonded together using an adhesive (SK1478, manufactured by Soken Chemical Co., Ltd.). Then, using a Tensilon universal tester RTF-2430 (manufactured by A&D Co., Ltd.), the peeled area was chucked, and the load value at the time of peeling between the first and second substrates was measured. The average value of the load in the strain-load curve between 20 and 80 mm was calculated as the adhesion force F (N / 25 mm), and evaluated according to the following criteria.

[0170] A:F≧1.0 B:1.0>F≧0.5 C:0.5>F≧0.3 D:0.3>F

[0171] (Spatial Resolution) A stainless steel indenter with a tip curvature of 0.25 mm was attached to a friction and wear testing machine (TYPE: 38, manufactured by Shinto Kagaku Co., Ltd.), and a weight was set to apply a load of 0.1 MPa. The load was then applied to the pressure-sensitive film from the linear polarizer side, opposite to the CMOS sensor side of the tactile sensor system prepared above. Next, with the load applied, the gray value in a 20 mm x 20 mm area was acquired using the CMOS sensor. The measured gray value in the non-applied area was set to 1, and the distance L (mm) from the load-applied end where the relative gray value was 1.2 was defined as the spatial resolution of the pressure sensitivity, and was evaluated according to the following criteria.

[0172] A: L≦0.1 B: 0.1<L≦1.0 C: 1.0<L≦2.0 D: 2.0<L

[0173] (Device Thickness) The total thickness of the tactile sensor system (hereinafter referred to as device thickness D) was measured using a caliper (Mitutoyo Digital Capacitor CD-P20S) and evaluated according to the following criteria.

[0174] A: D≦8 B: 8<D≦15 C:15<D≦29 D:29<D

[0175] [Example 2] A pressure-sensitive film was fabricated in the same manner as in Example 1, except that linear polarizing plates were used as the first and second supports. A tactile sensor system was fabricated by arranging the CMOS sensor and pressure-sensitive film in that order.

[0176] The pressure-sensitive film and tactile sensor system of Example 2 were evaluated in the same manner as in Example 1.

[0177] [Example 3] A pressure-sensitive film and a tactile sensor system were manufactured and evaluated in the same manner as in Example 2, except that the following adhesion layer (anchor layer) was formed between the partition wall and the first support when manufacturing the first substrate, and the following adhesion layer (anchor layer) was formed between the second support and the orientation film when manufacturing the second substrate.

[0178] <Preparation of Adhesion Layer Coating Solution> Adhesion layer coating solution A was prepared using the following formulation.

[0179] --------------------------------------------------- Adhesion layer coating liquid A --------------------------------------------------- Bremmer GLM (manufactured by NOF Corporation) 10 parts by mass Polymerization initiator Irgacure 819 (manufactured by BASF) 1 part by mass Methyl isobutyl ketone 89 parts by mass ---------------------------------------------------

[0180] <Formation of the Adhesion Layer> On each support, the prepared adhesion layer coating solution A was applied using a bar coater #4 to a coating amount that resulted in a film thickness of 1.0 μm. The film surface temperature was heated to 50°C and dried for 1 minute. Then, under a nitrogen purge with an oxygen concentration of 100 ppm or less, 500 mJ / cm² of ultraviolet light was irradiated using a 200 W / cm air-cooled metal halide lamp (manufactured by I-Graphics Co., Ltd.) to promote the polymerization reaction and produce the adhesion layer A. The irradiation dose was measured at a wavelength of 365 nm. A mercury lamp was used.

[0181] [Example 4] A pressure-sensitive film and a tactile sensor system are fabricated and evaluated in the same manner as in Example 3, except that the adhesion layer contained in the first substrate is formed using adhesion layer coating liquid B prepared as described below, and the adhesion layer contained in the second substrate is formed using adhesion layer coating liquid C prepared as described below.

[0182] --------------------------------------------------- Adhesion layer coating liquid B --------------------------------------------------- M-306 (manufactured by Toagosei Co., Ltd.) 10 parts by mass Polymerization initiator Irgacure 819 (manufactured by BASF) 1 part by mass Methyl isobutyl ketone 89 parts by mass ---------------------------------------------------

[0183] --------------------------------------------------- Adhesion layer coating liquid C --------------------------------------------------- Bremmer GLM (manufactured by NOF Corporation) 10 parts by mass M-306 (manufactured by Toagosei Co., Ltd.) 10 parts by mass Polymerization initiator Irgacure 819 (manufactured by BASF) 1 part by mass Methyl isobutyl ketone 89 parts by mass

[0184] [Example 5] A pressure-sensitive film and a tactile sensor system are fabricated and evaluated in the same manner as in Example 3, except that an adhesion layer is formed using the adhesion layer coating solution D prepared below.

[0185] --------------------------------------------------- Adhesion layer coating liquid D --------------------------------------------------- A-DPH (manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 10 parts by mass Polymerization initiator Irgacure 819 (manufactured by BASF) 1 part by mass Methyl isobutyl ketone 89 parts by mass ---------------------------------------------------

[0186] [Example 6] A pressure-sensitive film and a tactile sensor system were fabricated and evaluated in the same manner as in Example 3, except that the height h of the partition wall was set to 50 μm.

[0187] [Examples 7-11] Pressure-sensitive films and tactile sensor systems were fabricated and evaluated in the same manner as in Example 6, except that the height h, thickness t, and tensile modulus of the partition wall were changed as shown in Table 1.

[0188] [Example 12] In the preparation of the second substrate, a pressure-sensitive film and a tactile sensor system were fabricated and evaluated in the same manner as in Example 3, except that the transparent deformation layer described below was provided on the side of the second support opposite to the orientation film.

[0189] The transparent deformation layer was formed as follows.

[0190] A commercially available gel sheet (manufactured by Exceel Co., Ltd., product name: Hypergel Sheet 15 (HG01-30003)) was used as the transparent deformation layer. The Shore hardness of this transparent deformation layer was 15. The Shore hardness of the transparent deformation layer was measured using a Shore durometer according to the procedure described in ASTM D2240.

[0191] [Examples 13-15] Pressure-sensitive films and tactile sensor systems are fabricated and evaluated in the same manner as in Example 12, except that a transparent deformation layer is formed using a material whose Shore OO hardness of the transparent deformation layer is the value shown in Table 2.

[0192] [Comparative Example 1] <Preparation of the first and second substrates> Using a linear polarizing plate as a support, a polyamic acid orientation layer coating solution (JALS2096, manufactured by JSR) was applied to the linear polarizing plate as an orientation agent using a bar coater #1.6. Then, it was dried at a film surface temperature of 80°C for 3 minutes to form an orientation film, and the first and second substrates were prepared. At this time, the film thickness of the orientation film was 60 nm.

[0193] <Preparation of the spacer layer> A spacer layer dispersion was prepared using the following formulation.

[0194] -------------------------------------------------- Spacer layer dispersion -------------------------------------------------- Bead spacer SP-208 (manufactured by Sekisui Chemical Co., Ltd.) 100 parts by mass, amount to achieve a methyl isobutyl ketone solid content of 0.2% --------------------------------------------------

[0195] The prepared spacer layer dispersion was applied to the orientation film of the first substrate using an applicator in a 100 mm x 200 mm area with a clearance of 100 μm. The film surface was then heated to 60°C and dried for 1 minute to form the spacer layer.

[0196] <Preparation of pressure-sensitive film> After dropping 1 cc of liquid crystal cell forming composition (ZLI2806 (manufactured by Merck)) into the spacer layer of the first substrate prepared above, the second substrate was laminated onto the first substrate on which the liquid crystal cell forming composition was dropped, with the alignment film side facing outwards, and a pressure-sensitive film was prepared by laminating it with a laminator at a pressure of 0.5 MPa. The liquid crystal compound sealed in the prepared pressure-sensitive film is vertically oriented.

[0197] Using the fabricated pressure-sensitive film, a tactile sensor system was constructed in the same manner as in Example 2, and evaluated in the same manner as in Example 2.

[0198] [Reference Example 1] Using GelSight mini manufactured by GelSight as the tactile sensor system, the pressure sensitivity was evaluated in the same manner as in Example 1, except that when a load was applied according to the procedure described above, the distance L (mm) from the end of the load application area where the thickness direction displacement was 10% was defined as the spatial resolution of the pressure sensitivity using the included software.

[0199] [Reference Example 2] A tactile sensor (I-SCAN40) manufactured by Nitta Corporation was used as the tactile sensor system, and the pressure sensitivity was evaluated in the same manner as in Example 1, except that when a load was applied according to the procedure described above, the spatial resolution of the pressure sensitivity was defined as the distance L (mm) from the end of the load application part at which the electrical resistance value became 30 kΩ, using the attached software.

[0200] The composition of each example and comparative example is shown in Tables 1 and 2, and the evaluation results are shown in Table 3. Note that in Tables 1 and 2, only the resin components are listed in the columns for the adhesion layer and orientation film. Also, tensile modulus is abbreviated as modulus.

[0201]

[0202]

[0203]

[0204] Tables 1-3 show that the pressure-sensitive film of the present invention can achieve higher spatial resolution compared to the comparative example.

[0205] Furthermore, a comparison of Examples 1 to 5 shows that the spatial resolution is improved by setting the peeling force to 0.5 N / 25 mm or higher (evaluation B or higher).

[0206] Examples 6 to 8 show that the spatial resolution can be improved by making the wall thickness of the partition less than 100 μm and the height greater than 3 μm.

[0207] Examples 9 to 11 show that the spatial resolution can be improved by setting the elastic modulus of the partition wall to 0.5 GPa to 4.2 GPa.

[0208] Examples 12 to 15 show that providing a transparent deformation layer improves spatial resolution. Furthermore, it is found that a Shore OO hardness of 15 to 30 is more preferable for the transparent deformation layer.

[0209] The effects of the present invention are clear from the results above.

[0210] 10a-10h Pressure-sensitive film 12a-12f First substrate 14a-14f Second substrate 16 First support 18, 18b Partition 18a Partition section 20 Alignment film 22 Polarizer 24 Transparent deformation layer 26 Second support 28 Alignment film 30 Polarizer 32 Transparent deformation layer 40 Liquid crystal compound 50 Light reflection layer 100a-100b Tactile sensor system 102 Imaging section 104 Illumination section

Claims

1. A pressure-sensitive film comprising a first substrate and a second substrate, wherein the first substrate comprises a support and a partition disposed on the support, the partition divides the space between the support and the second substrate into a plurality of regions, and at least an oriented liquid crystal compound is contained within the plurality of divided regions.

2. The pressure-sensitive film according to claim 1, wherein the first substrate further includes a polarizer, or the support is a polarizer.

3. The pressure-sensitive film according to claim 1, wherein the second substrate includes a polarizer.

4. The pressure-sensitive film according to claim 2, wherein the second substrate includes a polarizer.

5. The pressure-sensitive film according to claim 1, wherein at least one of the first substrate and the second substrate further comprises an alignment film for aligning the liquid crystal compound.

6. The pressure-sensitive film according to claim 1, wherein the liquid crystal compound is vertically oriented.

7. The pressure-sensitive film according to claim 1, wherein the peeling force between the first substrate and the second substrate is 0.5 N / 25 mm or more.

8. The pressure-sensitive film according to claim 1, wherein the thickness of the partition wall is 0.005 mm to 2 mm, the height of the partition wall is 0.001 mm to 0.1 mm, and the tensile modulus of the partition wall is 100 MPa to 6000 MPa.

9. The pressure-sensitive film according to claim 1, wherein the first substrate further includes a transparent deformation layer, or the support is a transparent deformation layer, the Shore OO hardness of the transparent deformation layer is 5 to 60, and the thickness of the transparent deformation layer is 0.1 mm to 10 mm.

10. The pressure-sensitive film according to claim 1, wherein the second substrate further comprises a transparent deformation layer, the Shore OO hardness of the transparent deformation layer is 5 to 60, and the thickness of the transparent deformation layer is 0.1 mm to 10 mm.

11. A tactile sensor system comprising a pressure-sensitive film according to any one of claims 1 to 10, and an imaging unit.

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