JP6968370B2 - Detection member, robot hand, detection method - Google Patents

Description

The present invention relates to a detection member, a robot hand, and a detection method using the detection member. Specifically, the present invention relates to a detection member including a photoelastic polyurethane (pressure detection member) and a piezoelectric line (sliding force detection member) having an organic piezoelectric material, and a detection method using the detection member.

Conventionally, it has been proposed to use a polyurethane resin having photoelasticity as a pressure sensitive sensor. For example, Patent Document 1 proposes a touch panel including a polyurethane molded body for a pressure-sensitive sensor made of a polyurethane resin, and a light-emitting portion and a light-receiving portion provided so as to sandwich the polyurethane molded body for the pressure-sensitive sensor.

Further, Patent Document 2 proposes a photoelastic polyurethane resin capable of obtaining a detection member having excellent responsiveness particularly in a cold region.

Japanese Unexamined Patent Publication No. 2012-193293 International Publication No. 2016/125905 Pamphlet

Document 1 described above proposes a pressure measurement technique utilizing light passing through the inside of a plate-shaped photoelastic polyurethane resin and sensing a vertical force applied to the surface of the photoelastic polyurethane resin. Has been done. However, what is detected is a force in the direction perpendicular to the plate surface of the plate-shaped photoelastic polyurethane resin, and a means for detecting the force (sliding force) in the direction along the plate surface has been proposed so far. I wasn't.

An object of the present invention is to detect a force in a direction perpendicular to a plate surface of a plate-shaped photoelastic polyurethane resin and a force (sliding force) in a direction along the plate surface of the plate-shaped photoelastic polyurethane resin. Is.

According to the detection member according to the first aspect of the present invention, the pressure detection member formed in a plate shape using the photoelastic polyurethane resin and the pressure detection member are arranged facing the end face of the pressure detection member and directed toward the pressure detection member. A light emitting member that emits light, a light receiving member that receives light emitted by the light emitting member and passed through the pressure detecting member, and a pressure detecting member that has passed through the pressure detecting member between the pressure detecting member and the light receiving member. A polarizing member arranged on the optical path of light and a shearing force detecting member arranged along the plate surface of the pressure detecting member and outputting a detection signal according to the shearing force acting on the pressure detecting member are provided. ing.

According to the detection member according to the second aspect of the present invention, the shear force detecting member is embedded inside the pressure detecting member.

According to the detection member according to the third aspect of the present invention, the pressure detecting member is provided with a cushioning member which is in contact with the plate surface of the pressure detecting member and is formed by using an elastic material, and the shearing force detecting member is inside the cushioning member. It is buried in.

According to the detection member according to the fourth aspect of the present invention, the member is arranged between the pressure detection member and the light emitting member, and the polarization direction is 90 ° with respect to the polarization direction of the polarizing member. It is equipped with a polarizing member.

According to the detection member according to the fifth aspect of the present invention, the shear force detection member includes a long conductor and a piezoelectric material spirally wound in one direction with respect to the conductor and containing an organic piezoelectric material. Is formed including.

According to the detection member according to the sixth aspect of the present invention, the shear force detecting member is formed in a rod shape.

According to the detection member according to the seventh aspect of the present invention, the photoelastic polyurethane resin forming the pressure detection member has a Young's modulus of 2 MPa or more and 5 MPa or less at 25 ° C., and a photoelastic constant at 25 ° C. is 1000 ×. It is ^10-12 Pa ^-1 or more and 100,000 × 10 ^-12 Pa ^-1 or less, and the glass transition temperature is -60 ° C or more and -21 ° C or less.

According to the robot hand according to the eighth aspect of the present invention, a pair of finger portions that sandwich and grip the gripping object from both sides, and a detection member attached to one of the finger portions so as to come into contact with the gripping object. , Is equipped.

According to the detection method according to the ninth aspect of the present invention, it is a detection method for detecting a gripping state when the gripping object is gripped by using a robot hand and the gripping object is lifted by the light receiving member. The force that pinches the gripping object is detected based on the detected detection value, and the force is generated between the gripping object and the robot hand based on the detection value detected by the shear force detecting member. Detects sliding force.

According to the present invention, it is possible to detect a force in a direction perpendicular to a plate surface of a plate-shaped photoelastic polyurethane resin and a force (sliding force) in a direction along the plate surface of the plate-shaped photoelastic polyurethane resin. Can be done.

It is a block diagram which showed the detection member of the 1st specific example which concerns on embodiment of this invention. It is a block diagram which showed the detection member of the 2nd specific example which concerns on embodiment of this invention. It is a block diagram which showed the detection member of the 3rd specific example which concerns on embodiment of this invention. It is a block diagram which showed the detection member of the 4th specific example which concerns on embodiment of this invention. It is a block diagram which showed the detection member of the 5th specific example which concerns on embodiment of this invention. It is a block diagram which showed the detection member of the 6th specific example which concerns on embodiment of this invention. (A) (B) (C) (D) (E) It is a top view which showed the shape of the shear force detection member which concerns on embodiment of this invention. (A) (B) The detection member according to the sixth specific example according to the embodiment of the present invention is shown more concretely, a cross-sectional view cut along the longitudinal direction, and a direction orthogonal to the longitudinal direction. It is a cut sectional view. It is a figure which showed the output by the light receiving member provided in the detection member which concerns on embodiment of this invention in a graph. It is a block diagram which showed the robot hand which concerns on embodiment of this invention. It is a block diagram which showed the robot hand which concerns on embodiment of this invention. (A) (B) (C) (D) (E) (F) It is a process diagram which showed the process of gripping the gripping object by the gripping state detection method which concerns on embodiment of this invention. It is a figure which showed the output by a light receiving member, and the output by a shearing force detection member in a graph in the process of gripping a gripping object by the gripping state detection method which concerns on embodiment of this invention. It is a figure which showed the output by a light receiving member, and the output by a shearing force detection member in a graph in the process of gripping a gripping object by the gripping state detection method which concerns on embodiment of this invention. It is a flow diagram for demonstrating the process of gripping a gripping object by the gripping state detection method which concerns on embodiment of this invention. It is a flow diagram for demonstrating the process of gripping a gripping object by the gripping state detection method which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.

In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the present specification, the "face" of a member means the "main surface" of the member unless otherwise specified.
In the present specification, the angle formed by two line segments is expressed in the range of 0 ° or more and 90 ° or less.
As used herein, the term "film" is a concept that includes not only what is generally called "film" but also what is generally called "sheet".
As used herein, the "MD direction" is the direction in which the film flows (Machine Direction), that is, the stretching direction.

[Detection member]
The detection member of the present embodiment includes a plate-shaped pressure detection member containing a photoelastic polyurethane resin, a light emitting member arranged at a first position that emits light toward the pressure detection member, and preferably a pressure detection member. A first polarizing member arranged between the light emitting member and a light receiving member arranged at a second position different from the first position, which receives light emitted from the light emitting member and passed through the pressure detecting member. The second polarizing member arranged between the pressure detecting member and the light receiving member, and arranged inside the pressure detecting member or adjacent to the side surface of the pressure detecting member, and arranged along the plate surface of the pressure detecting member. It is equipped with a shear force detecting member.

According to the detection member of the present embodiment, it is possible to simultaneously detect the shearing force acting on the detection member while using the photoelastic polyurethane resin as the pressure-sensitive sensor.

Here, the "shear force (shear stress)" is a shear force (shear stress), which is a force (stress) that acts to slide in a direction parallel to a certain surface inside an object. In the present embodiment, it is a force in the direction along the plate surface of the pressure detecting member formed in the shape of a plate.

Hereinafter, each configuration of the detection member of the present embodiment will be described in detail.

<Pressure detection member>
The detection member of the present embodiment includes a pressure detection member. The pressure detecting member contains a photoelastic polyurethane resin.

Photoelasticity refers to the property that an elastic body that receives an external force causes birefringence. That is, the photoelastic polyurethane resin in the present embodiment means a polyurethane resin having photoelasticity among the polyurethane resins.

The material of the pressure detecting member is not particularly limited as long as it contains a photoelastic polyurethane resin and is transparent and exhibits photoelastic properties.

The shape of the pressure detecting member is preferably plate-shaped or sheet-shaped. The pressure detecting member is formed in a plate shape or a sheet by, for example, a molding die (casting die) having a predetermined shape, or is formed by cutting after demolding.

(Photoelastic polyurethane resin)
The photoelastic polyurethane resin can be obtained by reacting and curing a polyurethane resin composition containing a polyisocyanate component and an active hydrogen group-containing component.

The polyisocyanate component includes an aromatic ring-containing polyisocyanate. The aromatic ring-containing polyisocyanate is a 1,4-phenylene group (provided that some hydrogen atoms in the 1,4-phenylene group are substituted with a methyl group and / or a methoxy group), and / or. , 1,5-naphthylene group is contained.

Examples of the aromatic ring-containing polyisocyanate containing a 1,4-phenylene group include polymers of 4,4'-diphenylmethane diisocyanate (4,4'-MDI) and 4,4'-diphenylmethane diisocyanate (carbodiimide-modified MDI, Ureton imine-modified MDI, acylurea-modified MDI, etc.), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 3,3'-dimethylbiphenyl-4,4'-diisocyanate (TODI), 3,3'- Dimethoxybiphenyl-4,4'-diisocyanate, p-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 4,4'-diphenylether diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 1,4- Examples thereof include benzene ring-containing polyisocyanates (specifically, benzene ring-containing diisocyanates) such as xylylene diisocyanate (1,4-XDI).

The aromatic ring-containing polyisocyanate containing a 1,5-naphthylene group includes, for example, a naphthalene ring-containing polyisocyanate such as 1,5-naphthalene diisocyanate (1,5-NDI) (specifically, a naphthalene ring-containing polyisocyanate). Diisocyanate) and the like.

Of the aromatic ring-containing polyisocyanates containing a 1,4-phenylene group and / or a 1,5-naphthylene group, preferably 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 3,3'- Examples thereof include dimethylbiphenyl-4,4'-diisocyanate (TODI) and 1,5-naphthalenedi isocyanate (1,5-NDI).

The polyisocyanate component can be used alone or in combination of two or more. Preferably, 4,4'-MDI and TODI are used in combination.

Further, the polyisocyanate component may contain other polyisocyanates other than the aromatic ring-containing polyisocyanate as an optional component.

Examples of other polyisocyanates include aromatic polyisocyanates (excluding the above-mentioned aromatic ring-containing polyisocyanates), aromatic aliphatic polyisocyanates, (excluding the above-mentioned aromatic ring-containing polyisocyanates), alicyclic polyisocyanates, and fats. Examples thereof include group polyisocyanates.

Examples of the aromatic polyisocyanate include aromatic diisocyanates such as 2,2'-MDI, 2,6-TDI, m-phenylenediocyanate, and 2,6-NDI.

Examples of the aromatic aliphatic polyisocyanate include aromatic aliphatic diisocyanates such as 1,3-xylylene diisocyanate (1,3-XDI) and tetramethylxylylene diisocyanate (TMXDI).

Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate, IPDI), 4,4'-, 2,4'-or 2,2'-dicyclohexyl. Methandiisocyanate or a mixture thereof (H12MDI), 1,3-bis (isosyanatomethyl) cyclohexane (hydrogenated xylylene diisocyanate, H6XDI), 2,5- or 2,6-bis (isosyanatomethyl) norbornan or a mixture thereof (isocyanatomethyl) NBDI), 1,3-cyclopentane diisocyanate, 1,4- or 1,3-cyclohexanediisocyanate or a mixture thereof, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate and other alicyclic diisocyanates. Can be mentioned.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate (TMDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 1,2-, 2,3- or 1,3-butylenediocyanate. , 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate and the like.

Among the polyisocyanate components, the blending ratio of the aromatic ring-containing polyisocyanate containing a 1,4-phenylene group and / or a 1,5-naphthylene group is, for example, 30% by mass or more with respect to the total amount of the polyisocyanate component. More preferably, it is 50% by mass or more, and particularly preferably 90% by mass or more.

The aromatic ring concentration of the polyisocyanate component is, for example, 10% by mass or more, preferably 12% by mass or more, and usually, for example, 30% by mass or less, preferably 26% by mass or less, based on the polyurethane resin composition. , More preferably, it is 16% by mass or less.

When the aromatic ring concentration of the polyisocyanate component is at least the above lower limit, excellent photoelasticity can be obtained.

When the aromatic ring concentration of the polyisocyanate component is not more than the above-mentioned upper limit, excellent photoelasticity can be obtained.

The aromatic ring concentration of the polyisocyanate component is a mass ratio of the aromatic ring derived from the polyisocyanate component in the polyurethane resin composition, and does not include the aromatic ring derived from the cyano compound described later.

When the polyisocyanate component contains a 1,4-phenylene group, the aromatic ring concentration is such that the molecular weight of the polyisocyanate is 78 (g / mol), and the polyisocyanate component is a 1,5-naphthylene group. When the polyisocyanate is contained, the molecular weight of the polyisocyanate is calculated as 128 (g / mol).

The active hydrogen group-containing component is a compound having an active hydrogen group (for example, a hydroxyl group, an amino group, etc.), and examples thereof include polyols and polyamines, with preference given to polyols.

The polyol preferably contains a high molecular weight polyol.

The high molecular weight polyol is a compound having two or more hydroxyl groups and having an average hydroxyl value (described later) of 20 mgKOH / g to 500 mgKOH / g, and an average number of functional groups (described later) of 2, the number average molecular weight. Is a compound having a number of 225 or more, or when the average number of functional groups is 3, it is a compound having a number average molecular weight of 337 or more.

Examples of such high molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, dimer polyols, polyurethane polyols, polyoxyalkylene polyester block copolymer polyols, acrylic polyols, epoxy polyols, and natural oil polyols. Examples thereof include silicone polyols and fluoropolyesters.

Examples of the polyether polyol include polyoxyalkylene polyols such as polyalkylene (C2-C3) polyols and polytetramethylene ether polyols.

Examples of the polyalkylene (C2-C3) polyol include addition polymers of alkylene oxides such as ethylene oxide and propylene oxide having a low molecular weight polyol as an initiator (random and / or block copolymerization of two or more alkylene oxides). (Including coalescence). Specific examples thereof include polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer (random and / or block copolymer) and the like.

The low molecular weight polyol is a compound having two or more hydroxyl groups and having an average hydroxyl value (described later) exceeding 500 mgKOH / g, and when the number of functional groups (described later) is 2, the molecular weight is 40 or more and less than 225. Or, when the number of functional groups is 3, it is a triol having a molecular weight of 40 or more and less than 337.

Examples of such low molecular weight polyols include ethylene glycol, propylene glycol (1,2-propanediol), trimethylene glycol (1,3-propanediol), and 1,4-butylene glycol (1,4-butanediol). ), 1,3-butylene glycol (1,3-butanediol), 1,2-butylene glycol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentylglycol, 3-methyl- 1,5-Pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, alcohol (7 to 13 carbon atoms) diol, 1 , 4-Dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,8-diol and other aliphatic diols (2 to 13 carbon atoms) such as alkene (4 to 13 carbon atoms) diol, for example. Alicyclic diols such as cyclohexanedimethanol (6 to 13 carbon atoms), and further aromatic diols such as bishydroxyethoxybenzene and xylene glycol (aromatic ring-containing diols containing an aromatic ring and having 6 to 13 carbon atoms). ), Further, diols (2-9 carbon atoms) (dihydric alcohols) such as oxyalkylene alcohols such as diethylene glycol, trioxyethylene glycol, tetraoxyethylene glycol, dipropylene glycol, trioxypropylene glycol, for example, glycerin. 2-Methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, trimethylolpropane, 2,2-bis (hydroxymethyl) An aliphatic triol having 3 to 6 carbon atoms such as -3-butanol, and other triols (trihydric alcohols) such as an aliphatic triol (7 to 20 carbon atoms), for example, tetramethylolmethane (pentaerythritol), di Tetraol (tetrahydric alcohol) such as glycerin (diglycerol) (5-27 carbon atoms), such as pentaol (pentohydric alcohol) such as xylitol (5-33 carbon atoms), such as sorbitol, mannitol, aritol, Hexaol (hexahydric alcohol) such as iditol, darsitol, altritor, inositol, dipentaerythritol (6-40 carbon atoms), for example, heptao such as persetol. (R) (7 to 47 carbon atoms), for example, octaol (octavalent alcohol) such as sucrose (8 to 54 carbon atoms) and the like.

These low molecular weight polyols can be used alone or in combination of two or more.

Examples of the polytetramethylene ether polyol include an amorphous polytetramethylene ether glycol obtained by copolymerizing a ring-opening polymer obtained by cationic polymerization of tetrahydrofuran, for example, the above-mentioned diol with a polymerization unit of tetrahydrofuran, for example, tetrahydrofuran. Examples of the polymerization unit include amorphous polytetramethylene ether glycol obtained by copolymerizing ethylene oxide, propylene oxide, epiclohydrin and / or benzyl glycidyl ether and the like.

Further, as the polyether polyol, for example, the above-mentioned aromatic ring-containing diol having 6 to 13 carbon atoms (specifically, bishydroxyethoxybenzene or the like) and an aromatic ring-containing diol having a hydroxyl value of 500 mgKOH / g or less (specifically). Also includes an aromatic ring-containing polyol obtained by addition-polymerizing an aromatic diol such as bishydroxyethyl terephthalate, bisphenol A, etc. with ethylene oxide, propylene oxide and / or tetrahydrofuran.

Preferred examples of the polyether polyol include polytetramethylene ether glycol.

Examples of the polyester polyol include a polyester polyol obtained by reacting the above-mentioned low molecular weight polyol with a polybasic acid or an acid anhydride thereof or an acid halide thereof.

Examples of the polybasic acid and its acid anhydride or its acid halide include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, 1,1-dimethyl-1,3-dicarboxypropane, 3 -Methyl-3-ethylglutaric acid, azelaic acid, sebatic acid, other aliphatic dicarboxylic acids (C11-C13), hydrogenated dimer acid, maleic acid, fumaric acid, itaconic acid, orthophthalic acid, isophthalic acid, terephthalic acid , Toluenedicarboxylic acid, dimer acid, hetic acid and other carboxylic acids (dicarboxylic acids), and acid anhydrides derived from these carboxylic acids and the like, such as oxalic acid anhydride, succinic acid anhydride, maleic acid anhydride, phthalic acid anhydride. Acids, acid halides derived from acids, 2-alkyl anhydrides (C12-C18) succinic acid, tetrahydrophthalic acid anhydride, trimellitic acid anhydride, and these carboxylic acids anhydride, such as oxalic acid dichloride, adipic acid dichloride, etc. Examples thereof include dichloride on sebatic acid.

Further, as the polyester polyol, for example, a polycaprolactone polyol or a polyvalerolactone polyol obtained by ring-opening polymerization of lactones such as ε-caprolactone and γ-valerolactone using the above-mentioned low molecular weight polyol as an initiator. Examples thereof include lactone-based polyester polyols such as.

Further, as the polyester polyol, for example, the above-mentioned low molecular weight polyol and a hydroxycarboxylic acid such as a hydroxyl group-containing vegetable oil fatty acid (for example, a lysinoleic acid-containing castor oil fatty acid, a hydrogenated castor oil fatty acid containing 12-hydroxystearic acid, etc.) Examples thereof include vegetable oil-based polyester polyols obtained by subjecting them to a condensation reaction under known conditions.

The polycarbonate polyol can be obtained, for example, by reacting phosgene, dialkyl carbonate, diallyl carbonate, alkylene carbonate or the like with the above-mentioned low molecular weight polyol as an initiator in the presence or absence of a catalyst, for example. The polycarbonate polyol preferably includes a polycarbonate diol having a diol as an initiator.

Examples of the polyolefin polyol include a polybutadiene polyol and a polyisoprene diol having a hydroxyl group added to the end of a polymer of a conjugated double bond-containing monomer such as butadiene and isoprene.

Examples of the dimer polyol include dimerdiol obtained by reducing a dimer of an unsaturated fatty acid having 18 carbon atoms as a main component, which is usually available as an industrial raw material.

As the polyurethane polyol, the polyether polyol, the polyester polyol and / or the polycarbonate polyol obtained above are reacted with the above-mentioned polyisocyanate component at a ratio where the equivalent ratio (OH / NCO) of the hydroxyl group to the isocyanate group exceeds 1. Examples thereof include a polyether polyurethane polyol, a polyester polyurethane polyol, a polycarbonate polyurethane polyol, and a polyester polyether polyurethane polyol obtained by subjecting the mixture.

As the polyoxyalkylene polyester block copolymer polyol, for example, as described in Japanese Patent Publication No. 48-10078, a polyoxyalkylene polyol having a structure in which a polyester chain is blocked, that is, a polyoxyalkylene polyol or a polyoxyalkylene polyol or The portion of the derivative having a hydroxyl group that replaces the hydrogen atom of each hydroxy group is the general formula (A).

(-CO-R ⁵ -COO-R ^6- O-) _n (A)

(In the formula, R ⁵ and R ⁶ are divalent hydrocarbon groups, respectively, and n indicates a number larger than 1 on average.).

In Formula (A), examples of the divalent hydrocarbon group represented by R ^5, for example, saturated aliphatic or aromatic polycarboxylic acid residue, as the divalent hydrocarbon group represented by R ⁶ is, for example, , Residues in which the compound having a cyclic ether group is cleaved are mentioned, and n is preferably an integer of 1 to 20.

This polyoxyalkylene polyester block copolymer polyol can be obtained by reacting the above-mentioned polyoxyalkylene polyol (polyether polyol) with a polycarboxylic acid anhydride and an alkylene oxide.

The average hydroxyl value of the high molecular weight polyol is 20 mgKOH / g to 500 mgKOH / g, preferably 80 mgKOH / g to 300 mgKOH / g, and more preferably 100 mgKOH / g to 250 mgKOH / g.

The hydroxyl value (unit: mgKOH / g) of the high molecular weight polyol can be obtained from the acetylation method or the phthalation method based on the A method or the B method of JIS K 1557-1.

The average hydroxyl value (unit: mgKOH / g) of the high molecular weight polyol is the same as the hydroxyl value of the high molecular weight polyol when the high molecular weight polyol is used alone. On the other hand, the average hydroxyl value of the high molecular weight polyol is the average value of the high molecular weight polyols when they are used in combination.

If the average hydroxyl value of the high molecular weight polyol exceeds the above range, the Young's modulus of the photoelastic polyurethane resin becomes too high, and a desired photoelastic constant may not be obtained. On the other hand, if the average hydroxyl value is less than the above range, the glass transition temperature may become excessively low, and the processability and scratch resistance may decrease.

The average number of functional groups of the high molecular weight polyol is, for example, 1.9 to 3, preferably 1.9 to 2.5, and more preferably 2.0 to 2.2.

The number of functional groups of the high molecular weight polyol is the number of hydroxyl groups of the high molecular weight polyol, specifically, the number of active hydroxyl groups per molecule.

The average number of functional groups of the high molecular weight polyol is the average value of the active hydroxyl groups per molecule of the high molecular weight polyol. That is, when high molecular weight polyols having different functional groups are mixed (combined), the numerical value indicating the ratio of the number of active hydroxyl groups of the mixture to the number of molecules of the mixture of the high molecular weight polyol is the average of the high molecular weight polyols. The number of functional groups.

The average number of functional groups of the high molecular weight polyol can also be obtained from the following formula (B).

Average number of functional groups = total of (number of functional groups of each high molecular weight polyol x equivalent number) / total number of equivalent numbers of each high molecular weight polyol (B)

The number average molecular weight of the high molecular weight polyol is, for example, 225 to 20,000, preferably 500 to 15,000.

The number average molecular weight can be obtained from the following equation (C).

Number average molecular weight = 56100 x average number of functional groups / average hydroxyl value (C)

If the average number of functional groups of the high molecular weight polyol exceeds the above range, it may be difficult to obtain a desired photoelastic constant in the photoelastic polyurethane resin. On the other hand, if the average number of functional groups is less than the above range, the Young's modulus may become too low, and the processability and scratch resistance may decrease.

Preferred examples of the high molecular weight polyol include a polyether polyol, a polyester polyol, a polycarbonate polyol, and a polyolefin polyol.

More preferably, polytetramethylene ether polyol and polycarbonate polyol (specifically, polycarbonate diol) can be mentioned.

The average hydroxyl value of polytetramethylene ether glycol is 100 mgKOH / g to 250 mgKOH / g, preferably 100 mgKOH / g to 220 mgKOH / g. If the average hydroxyl value of the polytetramethylene ether glycol is within the above range, both high photoelasticity and high rigidity can be achieved.

The average hydroxyl value of the polycarbonate diol is 100 mgKOH / g to 250 mgKOH / g, preferably 150 mgKOH / g to 250 mgKOH / g. If the average hydroxyl value of the polycarbonate diol is within the above range, both high photoelasticity and high rigidity can be achieved.

These high molecular weight polyols can be used alone or in combination of two or more.

Further, the polyol may contain the above-mentioned low molecular weight polyol in addition to the above-mentioned high molecular weight polyol.

When the polyol contains a low molecular weight polyol, the average hydroxyl value of the polyol is increased, and the isocyanate index (described later) is adjusted to a desired value by that amount, so that the above-mentioned polyisocyanate component (preferably containing an aromatic ring) is contained. Polyisocyanate) can be blended in a large amount in the polyurethane resin composition. Therefore, the photoelastic constant of the photoelastic polyurethane resin can be increased.

Preferred low molecular weight polyols include diols, triols and tetraols, and specific examples thereof include diols having 2 to 10 carbon atoms, triols having 3 to 10 carbon atoms and tetraols having 5 to 10 carbon atoms. Be done.

Examples of the diol having 2 to 10 carbon atoms include ethylene glycol, propylene glycol, trimethylene glycol (1,3-propanediol), 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, and 2 -Methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,6-hexane Glycol, 2-ethyl-1,3-hexanediol, alkane (7 to 10 carbon atoms) diol, 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,8-diol, etc. Aromas of aliphatic diols (2 to 10 carbon atoms) such as alkene (4 to 10 carbon atoms) diols and alicyclic diols (6 to 10 carbon atoms) such as cyclohexanedimethanol, such as xylene glycol. Group diols (aromatic ring-containing diols having 6 to 10 carbon atoms), and diols such as oxyalkylene alcohols such as diethylene glycol, trioxyethylene glycol, tetraoxyethylene glycol, dipropylene glycol, and trioxypropylene glycol (2 carbon atoms). 10) and the like.

Examples of triols having 3 to 10 carbon atoms include glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, and 1,2,6-hexanetriol. , Trimethylolpropane, aliphatic triols having 3 to 6 carbon atoms such as 2,2-bis (hydroxymethyl) -3-butanol, and other triols such as aliphatic triols (7 to 10 carbon atoms). Be done.

Examples of tetraol having 5 to 10 carbon atoms include tetraol such as tetramethylolmethane and diglycerin.

Further, examples of the low molecular weight polyol include polyalkylene oxides having a number average molecular weight of 400 or less. Such a polyalkylene oxide is made of polyethylene glycol (polyoxyethylene), for example, by subjecting the above-mentioned low molecular weight polyol (diol, triol, etc.) as an initiator to an addition reaction with an alkylene oxide such as an ethylene oxide and / or a propylene oxide. It can be obtained as ether glycol), polypropylene glycol (polyoxypropylene ether glycol), polyethylene polypropylene glycol (random or block copolymer) and the like.

The low molecular weight polyols can be used alone or in combination of two or more.

Preferably, at least triol is used, and specific examples thereof include the single use of triol having 3 to 10 carbon atoms and the combined use of triol having 3 to 10 carbon atoms and a diol having 2 to 10 carbon atoms.

The blending ratio of the low molecular weight polyol is, for example, 0.1 part by mass to 30 parts by mass, preferably 0.5 part by mass to 25 parts by mass with respect to 100 parts by mass of the high molecular weight polyol.

When triol having 3 to 10 carbon atoms is used alone, the mixing ratio of triol having 3 to 10 carbon atoms is, for example, 10 parts by mass or less, preferably 9 parts by mass, based on 100 parts by mass of the high molecular weight polyol. Parts or less, more preferably 0.5 parts by mass to 6 parts by mass.

When the blending ratio of the triol having 3 to 10 carbon atoms exceeds the above range, the photoelastic polyurethane resin becomes opaque, the light does not pass through the photoelastic polyurethane resin, or the young ratio of the photoelastic polyurethane resin becomes high. It may be too much.

When a triol having 3 to 10 carbon atoms and a diol having 2 to 10 carbon atoms are used in combination, the blending ratio of the triol having 3 to 10 carbon atoms is, for example, 0.5 mass by mass with respect to 100 parts by mass of the high molecular weight polyol. 10 parts by mass, preferably 0.6 parts by mass to 6 parts by mass, and the blending ratio of the diol having 2 to 10 carbon atoms is, for example, 25 parts by mass or less with respect to 100 parts by mass of the high molecular weight polyol. It is preferably 0.1 part by mass to 10 parts by mass. When the blending ratio of the triol having 3 to 10 carbon atoms and the diol having 2 to 10 carbon atoms is within the above range, both high photoelasticity and high rigidity can be achieved.

When a triol having 3 to 10 carbon atoms and a diol having 2 to 10 carbon atoms are used in combination, the total amount thereof is, for example, 0.1 part by mass to 100 parts by mass with respect to 100 parts by mass of the high molecular weight polyol. It is 30 parts by mass, preferably 0.5 parts by mass to 25 parts by mass, and more preferably 0.7 parts by mass to 6 parts by mass.

If the total amount of triol and diol is less than the above range, Young's modulus may be excessively lowered, moldability and scratch resistance may be lowered, and the photoelastic constant may be lowered. If the total amount of triol and diol exceeds the above range, Young's modulus may become excessively high.

As for the blending ratio of the active hydrogen group-containing component, the high-molecular-weight polyol in the active hydrogen group-containing component is, for example, 120 parts by mass to 400 parts by mass, preferably 125 parts by mass with respect to 100 parts by mass of the polyisocyanate component. Parts to 333 parts by mass.

In other words, the content ratio of the polyisocyanate component is, for example, 25 parts by mass to 85 parts by mass, preferably 30 parts by mass to 80 parts by mass with respect to 100 parts by mass of the high molecular weight polyol. When the content ratio of the polyisocyanate component is within the above range, both high rigidity and high rigidity can be achieved at the same time.

When the content ratio of the polyisocyanate component exceeds the above range, the Young's modulus becomes excessively high, and the desired photoelastic constant in the photoelastic polyurethane resin may not be obtained.

When the content ratio of the polyisocyanate component is less than the above range, the desired photoelastic constant in the photoelastic polyurethane resin may not be obtained.

Further, the polyurethane resin composition of the present invention may contain a plasticizer.

The plasticizer is optionally incorporated into the polyurethane resin composition to lower the glass transition temperature of the photoelastic polyurethane resin, such as cyano compounds, phthalates (eg, di-2-ethylhexyl phthalates, diisononyl phthalates (eg, di-2-ethylhexyl phthalates, diisononyl phthalates). DINP))), eg, adipic acid ester (eg, dioctyl adipate), eg, sebacic acid ester (eg, dioctyl sebacate), triglycidyl phosphate, tributyl acetylcitrate, epoxidized soybean oil, trioctyl trimellitic acid, Alkylbenzene, alkylbiphenyl (eg 4-pentylbiphenyl), chlorinated paraffin, high boiling point solvent, ionic liquid (eg 1-ethyl-2,3-dimethylimidazolium bis (trifluoromethanesulfonyl) imide), polyester plasticizer And so on. Preferred are cyanide compounds.

By blending the cyano compound with the polyurethane resin composition, the Young's modulus of the molded product can be reduced, thereby improving the processability of the photoelastic polyurethane resin and increasing the photoelastic constant. can.

The cyano compound has, for example, 14 to 24 carbon atoms and has a 4-cyanophenyl group (provided that some hydrogen atoms in the 4-cyanophenyl group are substituted with fluorine atoms). ing.

By having the 4-cyanophenyl group in the cyano compound, the photoelastic constant can be further increased.

In the 4-cyanophenyl group, the hydrogen atom substituted by the fluorine atom is, for example, a hydrogen atom at the 2-position to a 6-position, preferably a hydrogen atom at the 2-position.

Specifically, the cyanide compound is a biphenyl compound represented by the following formula (1).

(In the formula, R ¹ represents an alkyl group having 1 to 11 carbon atoms, a 4-alkylphenyl group having 7 to 11 carbon atoms, or a 4-alkylcyclohexyl group having 7 to 11 carbon atoms.)

The ether compound represented by the following formula (2),

Specifically, the cyanide compound is a biphenyl compound represented by the following formula (1).

(In the formula, R ¹ represents an alkyl group having 1 to 11 carbon atoms, a 4-alkylphenyl group having 7 to 11 carbon atoms, or a 4-alkylcyclohexyl group having 7 to 11 carbon atoms.)

(In the formula, R ² represents an alkyl group having 1 to 11 carbon atoms.)

The cyclohexyl compound represented by the following formula (3),

(R ³ represents an alkyl group having 1 to 11 carbon atoms or an alkenyl group having 5 to 11 carbon atoms.)

Examples thereof include a phenyl ester compound represented by the following formula (4).

^{(R 4} is a hydrogen atom or a carbon atoms exhibits 1-10 alkyl group.)

In the above formula (1) ^{, examples of the alkyl group having 1 to 11 carbon atoms represented by R 1} include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, tert-pentyl and hexyl. , Heptyl, octyl, nonyl, isononyl, decyl, dodecyl and other linear or branched alkyl groups. Preferred are alkyl groups having 2 to 7 carbon atoms.

In the above formula (1) ^{, examples of the 4-alkylphenyl group having 7 to 11 carbon atoms represented by R 1} include 4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl and 4-. Examples thereof include a 4-alkylphenyl group having a linear or branched alkyl moiety having 1 to 5 carbon atoms, such as pentylphenyl, 4-isopentylphenyl, 4-tertpentylphenyl. Preferably, a 4-alkylphenyl group having 9 to 11 carbon atoms having an alkyl moiety having 3 to 5 carbon atoms can be mentioned.

Examples of the 4-alkylcyclohexyl group having 7 to 11 carbon atoms include 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-propylcyclohexyl, 4-isoipropylcyclohexyl, 4-pentylcyclohexyl, 4-isopentylcyclohexyl, and 4 -Tert Pentylcyclohexyl, a 4-alkylcyclohexyl group having a linear or branched alkyl moiety of 1-5 carbons. Preferably, a 4-alkylcyclohexyl group having 9 to 11 carbon atoms having an alkyl moiety having 3 to 5 carbon atoms can be mentioned.

^{As R 1 represented} by the above formula (1), an alkyl group having 1 to 11 carbon atoms and a 4-alkylcyclohexyl group having 7 to 11 carbon atoms are preferably mentioned.

Specific examples of the biphenyl compound represented by the above formula (1) include 4-cyano-4'-methylbiphenyl, 4-cyano-4'-pentylbiphenyl, and 4-cyano-4'-(4-pentylcyclohexyl). Biphenyl and the like can be mentioned.

In the above formula (2), examples of the alkyl group having 1 to 11 carbon atoms represented by ^{R 2} include an alkyl group similar to the alkyl group having 1 to 11 carbon atoms represented by ^{R 1 in the above formula (1).} ..

Specific examples of the ether compound represented by the above formula (2) include 4-cyano-4'-pentyloxybiphenyl.

In the above formula (3), ^{examples of the alkyl group having 1 to 11 carbon atoms represented by R 3} include an alkyl group similar to the alkyl group having 1 to 11 carbon atoms represented by ^{R 1} in the above formula (1). Be done.

In the above formula (3), the alkenyl group of the number of carbon atoms represented by R ³ is 5 to 11, for example, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decynyl, dodecynyl and the like.

In the above formula (3), R ³ is preferably an alkyl group having 1 to 11 carbon atoms.

Specific examples of the cyclohexyl compound represented by the above formula (3) include 4- (4-pentylcyclohexyl) benzonitrile, 4-((3-pentenyl) -4-cyclohexyl) benzonitrile, and 2-fluoro-4. -(4-Pentylcyclohexyl) benzonitrile and the like can be mentioned.

In the above formula (4), the alkyl group having 1 to 10 carbon atoms represented by ^{R 4} is among the alkyl groups exemplified as the alkyl group having 1 to 11 carbon atoms represented by ^{R 1 of the above formula (1).} Examples thereof include alkyl groups similar to alkyl groups having 1 to 10 carbon atoms.

Examples of the phenyl ester compound represented by the above formula (4) include 4-cyanophenyl 4-propyl benzoate, 4-cyanophenyl 4-heptyl benzoate, and 4-cyano-3,5-diflu 4-pentyl benzoate. Examples include loophenyl.

Moreover, as a cyano compound, for example, cyanobenzene, 4-methoxybenzene and the like can be mentioned.

The cyanide compound can be used alone or in combination of two or more.

Among the cyano compounds, a biphenyl compound is preferable.

The blending ratio of the plasticizer is, for example, 100 parts by mass or less, preferably 1 part by mass to 60 parts by mass, and more preferably 5 parts by mass to 30 parts by mass with respect to 100 parts by mass of the high molecular weight polyol.

When the blending ratio of the plasticizer exceeds the above range, the Young's modulus of the photoelastic polyurethane resin may be excessively lowered, and the appearance of the photoelastic polyurethane resin may become opaque.

Then, a polyurethane resin composition is obtained by prescribing (blending) the above-mentioned polyisocyanate component, active hydrogen group-containing component, and if necessary, a plasticizer.

As a suitable combination of each component to be blended in the polyurethane resin composition, for example, a combination of an aromatic ring-containing polyisocyanate containing a 1,4-phenylene group, a polyether polyol, and a triol having 3 to 10 carbon atoms is used. Specific examples thereof include a combination of a benzene ring-containing diisocyanate, a polytetramethylene ether polyol, and an aliphatic triol having 3 to 6 carbon atoms, preferably a benzene ring-containing diisocyanate and a polytetramethylene ether. It consists only of a combination of a polyol and an aliphatic triol having 3 to 6 carbon atoms.

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, an aromatic ring-containing polyisocyanate containing a 1,4-phenylene group, a polyether polyol, a diol having 2 to 10 carbon atoms, and the like. Examples thereof include a combination with triol having 3 to 10 carbon atoms, specifically, a benzene ring-containing diisocyanate, a polytetramethylene ether polyol, an aliphatic diol having 2 to 10 carbon atoms, and a fat having 3 to 6 carbon atoms. The combination with the triol triol can be mentioned.

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, a plurality of kinds of aromatic ring-containing polyisocyanates, polyether polyols, diols having 2 to 10 carbon atoms, and diols having 3 to 10 carbon atoms are used. Examples thereof include a combination with triol, specifically, a benzene ring-containing diisocyanate, a naphthalene ring-containing diisocyanate, a polytetramethylene ether polyol, an aliphatic diol having 2 to 10 carbon atoms, and an aliphatic diol having 3 to 6 carbon atoms. Examples thereof include a combination with triol, or a combination of two different types of benzene ring-containing diisocyanates, a polytetramethylene ether polyol, an aliphatic diol having 2 to 10 carbon atoms, and an aliphatic triol having 3 to 6 carbon atoms. ..

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, an aromatic ring-containing polyisocyanate containing a 1,4-phenylene group, a polyether polyol, a diol having 2 to 10 carbon atoms, and the like. Examples thereof include a combination of a triol having 3 to 10 carbon atoms and a plasticizing agent, specifically, a benzene ring-containing diisocyanate, a polytetramethylene ether polyol, an aliphatic diol having 2 to 10 carbon atoms, and 3 carbon atoms. Examples thereof include a combination of the aliphatic triol of ~ 6 and a biphenyl compound.

Furthermore, suitable combinations of the components formulated in the polyurethane resin composition include, for example, an aromatic ring-containing polyisocyanate containing a 1,4-phenylene group, a polycarbonate polyol, and triol having 3 to 10 carbon atoms. Examples thereof include a combination with a plasticizer, and specific examples thereof include a combination of a benzene ring-containing diisocyanate, a polycarbonate diol, an aliphatic triol having 3 to 6 carbon atoms, and a biphenyl compound.

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, a plurality of types of aromatic ring-containing polyisocyanates containing 1,4-phenylene groups, polyether polyols, and 2 to 10 carbon atoms are used. Examples thereof include a combination of a diol, a triol having 3 to 10 carbon atoms, and a plasticizing agent. Specifically, two different types of benzene ring-containing diisocyanates, a polytetramethylene ether polyol, and a fat having 2 to 10 carbon atoms are used. Examples thereof include a combination of a group diol, an aliphatic triol having 3 to 6 carbon atoms, and a biphenyl compound or an ether compound.

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, a combination of a plurality of types of aromatic ring-containing polyisocyanates, a polycarbonate polyol, and a triol having 3 to 10 carbon atoms can be mentioned. Examples thereof include a combination of a benzene ring-containing diisocyanate and a naphthalene ring-containing diisocyanate, a polycarbonate diol, and an aliphatic triol having 3 to 10 carbon atoms.

Further, as a suitable combination of each component prescribed in the polyurethane resin composition, for example, a combination of an aromatic ring-containing polyisocyanate containing a 1,4-phenylene group, a polyester polyol, and a triol having 3 to 10 carbon atoms. Specific examples thereof include a combination of a benzene ring-containing polyisocyanate, a polyester diol which is a polycondensate of a dicarboxylic acid and a diol, and an aliphatic triol having 3 to 10 carbon atoms.

The photoelastic polyurethane resin can be obtained by reacting the polyisocyanate with the polyol from the polyurethane resin composition thus obtained to cure and mold the polyurethane resin composition.

In order to react the polyisocyanate component with the active hydrogen group-containing component, a known molding method such as a one-shot method or a prepolymer method can be applied.

In the one-shot method, for example, the polyisocyanate component and the active hydrogen group-containing component have an isocyanate index (value obtained by multiplying the ratio of the isocyanate group concentration to the hydroxyl group concentration by 100, NCO concentration / hydroxyl group concentration × 100), for example, 70. Prescribed (mixed) to ~ 400, preferably 80 to 150, and injected into a mold, for example, at 0 ° C. to 250 ° C., preferably at room temperature (20 ° C.) to 150 ° C. For example, the curing reaction is carried out for 1 minute to 7 days, preferably 10 minutes to 2 days.

When 4,4'-MDI and TODI are used in combination as the polyisocyanate component, in order to react the polyisocyanate component with the active hydrogen group-containing component, first, the high molecular weight polyol and TODI are reacted. A reaction product (hydroxyl terminal) of a high molecular weight polyol and TODI is obtained. At this time, the isocyanate index of the high molecular weight polyol and TODI is, for example, 1 or more, for example, less than 100, preferably 50 or less.

Next, a low molecular weight polyol is blended with the reaction product of the high molecular weight polyol and TODI (hydroxyl end), the reaction product of the high molecular weight polyol and TODI (hydroxyl end), the low molecular weight polyol, and 4,4'. -Prescribe (mix) with MDI. At this time, the isocyanate index of the reactant (hydroxyl terminal) of the high molecular weight polyol and TODI, and the isocyanate index of the low molecular weight polyol and 4,4'-MDI exceeds 100, preferably 100.1 or more. Yes, for example, 110 or less.

In the curing reaction, a urethanization catalyst can be added. Examples of the urethanization catalyst include a tin-based catalyst (for example, tin octylate), a lead-based catalyst (for example, lead octylate), a bismuth-based catalyst, a titanium-based catalyst, a zirconium-based catalyst, an organic metal-based catalyst, and an amine. Examples include system catalysts.

The blending ratio of the urethanization catalyst is, for example, 0.0001 part by mass to 2.0 parts by mass, preferably 0.0005 parts by mass to 1.0 part by mass with respect to 100 parts by mass of the polyisocyanate component.

Further, the above-mentioned curing reaction can also be carried out in the presence of a known solvent.

Then, by injecting it into a molding die, subjecting it to a curing reaction, and then removing the mold, a photoelastic polyurethane resin molded into a predetermined shape can be obtained.

In the prepolymer method, for example, first, a polyisocyanate component and a part of an active hydrogen group-containing component (for example, a high molecular weight polyol) are reacted to synthesize an isocyanate group-terminated prepolymer having an isocyanate group at the molecular terminal. Next, the obtained isocyanate group-terminated prepolymer and the rest of the active hydrogen group-containing component (chain extender: for example, a low molecular weight polyol (and, if necessary, a high molecular weight polyol, monool)) are reacted (chain extension). And let it cure.

In order to synthesize an isocyanate group-terminated prepolymer, the isocyanate index (NCO concentration / hydroxyl group concentration × 100) of the polyisocyanate component and a part of the active hydrogen group-containing component is, for example, 110 to 2,000, preferably 110 to 2,000. It is formulated (mixed) so as to be 150 to 1,000, and in a reaction vessel, for example, at room temperature to 150 ° C., preferably 40 ° C. to 120 ° C., for example, 0.5 hour to 18 hours, preferably. React for 2 to 10 hours.

The above-mentioned isocyanate group-terminated prepolymer can be synthesized in the presence of a known solvent.

Further, after the synthesis of the above-mentioned isocyanate group-terminated prepolymer, the solvent and the unreacted polyisocyanate component are removed by a distillation method such as a thin film distillation method, for example, an extraction method such as a liquid-liquid extraction method. You can also do it.

The obtained isocyanate group-terminated prepolymer has an isocyanate equivalent of, for example, 80 to 2,000, preferably 100 to 1,000.

Next, in order to react the obtained isocyanate group-terminated prepolymer with the remainder of the active hydrogen group-containing component, the isocyanate group-terminated prepolymer and the remainder of the active hydrogen group-containing component are subjected to an isocyanate index (NCO concentration /). The hydroxyl group concentration × 100) is formulated (mixed) so as to be, for example, 50 to 200, preferably 75 to 125, and injected into a molding die, for example, 0 ° C to 250 ° C, preferably room temperature (20). The curing reaction is carried out at ° C.) to 150 ° C. for, for example, 1 minute to 7 days, preferably 10 minutes to 2 days.

Also in this curing reaction, the same urethanization catalyst as described above can be added in the same blending ratio as described above. Further, this curing reaction can also be carried out in the presence of a known solvent.

Then, by injecting it into a molding die, subjecting it to a curing reaction, and then removing the mold, a photoelastic polyurethane resin molded into a predetermined shape can be obtained.

Such a photoelastic polyurethane resin can cause birefringence in the light passing through the inside of the molded body (for example, laser light) due to photoelasticity, that is, the generation of stress. Therefore, it can be suitably used as a sensor.

Further, the above-mentioned polyurethane resin composition or photoelastic polyurethane resin may be, if necessary, for example, a defoaming agent, a plasticizer, a leveling agent, a matting agent, a flame retardant, a rocking agent, an antistatic agent, and a thickening agent. Known additives such as agents, lubricants, antistatic agents, surfactants, reaction retarders, dehydrating agents, antioxidants, ultraviolet absorbers, antioxidants, and weatherproof stabilizers can be appropriately added.

The photoelastic constant of the photoelastic polyurethane resin at 25 ° C. is, for example, 1000 × 10 ^-12 Pa ^-1 or more, preferably 2000 × 10 ^-12 Pa ^-1 or more, more preferably 3000 × 10 ^-12 Pa ^-1. The above is even more preferably 3500 × 10 ^-12 Pa ^-1 or more, further preferably 4000 × 10 ^-12 Pa ^-1 or more, and for example, 100 000 × 10 ^-12 Pa ^-1 or less, preferably 100,000 × 10 -12 Pa -1 or less. It is 10000 × 10 ^-12 Pa ^-1 or less, more preferably 6000 × 10 ^-12 Pa ^-1 or less, and even more preferably 5500 × 10 ^-12 Pa ^-1 or less.

That is, the photoelastic constant of the photoelastic polyurethane resin at 25 ° C. ^{is preferably 1000 × 10-12} Pa ^-1 or more and 100,000 × 10 ^-12 Pa ^-1 or less.

When the photoelastic constant exceeds the above-mentioned lower limit, excellent photoelasticity can be ensured.

The photoelastic constants of photoelastic polyurethane resin are described in "Development of Photoelastic Constant Measurement System for Optical Films" by Mitsuo Tsukiji, Hiroyuki Takakazu, and Yoshiro Tadashi, Journal of the Japan Society of Precision Science 73, 253-258 (2007). It can be measured according to the description of "Photoelastic constant measuring method".

Further, along with the measurement of the photoelastic constant, the strain optical constant and Young's modulus of the photoelastic polyurethane resin are obtained.

The strain optical constant of the photoelastic polyurethane resin indicates the ratio of the strength of birefringence generated by such deformation to the amount of deformation of the photoelastic polyurethane resin.

The photoelastic constant, the distorted optical constant, and Young's modulus satisfy the following equation (5).

Photoelastic constant = Distorted optical constant ÷ Young's modulus (5)

Therefore, in order to set the photoelastic constant of the photoelastic polyurethane resin in the above-mentioned desired range, it is preferable to adjust the strain optical constant and Young's modulus.

Specifically, the higher the distorted optical constant and the lower the Young's modulus, the higher the photoelastic constant, but if the Young's modulus is excessively low, the moldability may decrease.

Therefore, the Young's modulus of the photoelastic polyurethane resin at 25 ° C. is, for example, 2 MPa or more, preferably 3 MPa or more, and for example, 5 MPa or less.

That is, the Young's modulus of the photoelastic polyurethane resin at 25 ° C. is preferably 2 MPa or more and 5 MPa or less.

When the Young's modulus of the photoelastic polyurethane resin is less than the above range, the photoelastic polyurethane resin may be too soft and easily scratched, resulting in poor workability. When the Young's modulus of the photoelastic polyurethane resin exceeds the above range, the photoelastic polyurethane resin is too hard, and the photoelasticity may decrease.

Preferably, in order to obtain the above-mentioned desired photoelastic constant, when the Young's modulus of the photoelastic polyurethane resin at 25 ° C. is 2 MPa or more and 3 MPa or less, the strain optical constant at 25 ° C. is, for example, 6000 × 10 ^{−. 6} or more (usually, 10000 × ^{10 -6} or less), and when 25 ° C. Young's modulus of photoelasticity polyurethane resin is less than 5MPa exceed 3MPa, the strain-optical constants of 25 ° C., for example, 10000 × 10 ^-6 or more (usually 20000 × 10 ^-6 or less).

The glass transition temperature of the photoelastic polyurethane resin is, for example, −60 ° C. or higher, preferably −40 ° C. or higher, more preferably −35 ° C. or higher, even more preferably −30 ° C. or higher, for example, -21. ° C or lower, preferably −25 ° C or lower.

That is, the glass transition temperature of the photoelastic polyurethane resin is preferably −60 ° C. to -21 ° C.

If the glass transition temperature of the photoelastic polyurethane resin is less than the above-mentioned lower limit, the processability and scratch resistance of the photoelastic polyurethane resin may decrease.

Further, when the glass transition temperature of the photoelastic polyurethane resin is equal to or higher than the above-mentioned upper limit, it may be difficult to obtain the above-mentioned desired photoelastic constant.

The glass transition temperature of the photoelastic polyurethane resin can be obtained by measuring the temperature dispersion mode (heating rate 5 ° C./min) at a frequency of 10 Hz using a dynamic viscoelasticity measuring device.

Further, in the above-mentioned measurement of the glass transition temperature, a storage elongation elastic modulus E ′, a loss elongation elastic modulus E ″ and a loss tangent tan δ can be obtained at the same time.

The storage elongation elastic modulus E'at 25 ° C. of the photoelastic polyurethane resin is, for example, 1 × 10 ⁶ Pa to 1 × 10 ⁸ Pa, and the loss elongation elastic modulus E'' at 25 ° C. is, for example, 1 × 10 ⁴ It is Pa to 1 × 10 ⁸ Pa, and the loss tangent tan δ at 25 ° C. is, for example, 0.01 to 0.2.

Further, when the glass transition temperature of the photoelastic polyurethane resin is equal to or higher than the above-mentioned upper limit, the response time of the sensor at a low temperature may be long (the response speed may be slow).

The response time of the sensor is preferably within 100 milliseconds, more preferably within 10 milliseconds, and even more preferably within 1 millisecond. When the response time of the sensor is within the above range, the robot can be reliably controlled by detecting the contact with the object.

The temperature of the environment in which the sensor is used is, for example, −10 ° C. or higher, for example, 40 ° C. or lower.

Here, when the temperature of the operating environment of the sensor decreases and the temperature of the operating environment of the sensor and the glass transition temperature of the photoelastic polyurethane resin are close to each other, the loss elongation elastic modulus E'' of the photoelastic polyurethane resin increases. The response speed to external force tends to be slow.

When the glass transition temperature of the photoelastic polyurethane resin is equal to or lower than the above-mentioned upper limit, the response speed to an external force can be ensured even if the temperature of the use environment is −10 ° C.

<Light emitting member>
The detection member of this embodiment includes a light emitting member. The light emitting member is a member that emits light toward the pressure detecting member.

Examples of the light emitting member include a light emitting diode (LED). As the LED, various LEDs such as a red LED, a white LED, an infrared LED, a green LED, and a blue LED can be used. In addition to LEDs, for example, semiconductor lasers (wavelength 405 nm to 1064 nm), fluorescent lamps, halogen lamps, tungsten lamps and the like can also be used.

In the detection member of this embodiment, the light emitting member is arranged at the first position. The first position is not particularly limited as long as the light is emitted toward the pressure detecting member and the emitted light can be incident on the pressure detecting member. Further, the number of light emitting members is not limited.

<Light receiving member>
The detection member of this embodiment includes a light receiving member. The light receiving member is a member that receives light emitted from the light emitting member and passed through the pressure detecting member.

As the light receiving member, for example, a photodiode can be used. Further, in addition to a normal photodiode, a photo IC diode can also be used. The photoIC diode has a built-in photocurrent amplification circuit inside a normal photodiode, and amplifies the photocurrent generated by the photodiode 1000 times to several 1000 times and outputs it to the outside. When a normal photodiode is used, it is preferable to connect a known amplifier circuit to the photodiode to amplify the photocurrent by about 1000 to 10000 times.

Further, a known detector may be used as a light receiving member other than the photodiode. As a known detector, for example, a photoconductive type detector such as a phototransistor or a CdS cell, a heat-sensitive photodetector such as a bolometer, or the like can also be used.

In the detection member of the present embodiment, the light receiving member is arranged at a second position different from the first position. The second position is not particularly limited as long as it can receive light from the light emitting member via the pressure detecting member. Further, the number of light receiving members is not limited.

Further, as shown in FIGS. 5 and 6, when the light emitting member (reference numeral 18) and the light receiving member (reference numeral 20) are close to each other, a light emitting member (light emitting element) called a photoreflector or a photointerplater is used. ) And a light receiving member (light receiving element) may be integrated.

<First polarizing member>
The detection member of this embodiment includes a first polarizing member. The first polarizing member is a member that converts light (light rays) emitted from a light emitting member and incident on a pressure detecting member into linearly polarized rays or circularly polarized rays. As the first polarizing member, a linear polarizing plate or a circular polarizing plate made of glass or resin can be used.

The polarization direction of the first polarizing member is preferably an angle of about 45 ° with the upper surface of the pressure detecting member. When a laser beam having a constant polarization plane is used for the light emitting member, the first polarizing member may not be used because the laser beam is already polarized.

<Second polarizing member>
The detection member of this embodiment includes a second polarizing member. The second polarizing member is a member that converts light (light rays) that have passed through the pressure detecting member into linearly polarized rays or circularly polarized rays in front of the light receiving member. A linear polarizing plate or a circular polarizing plate made of glass or resin can be used for the second polarizing member, but when the first polarizing member is a linear polarizing plate, the linear polarizing plate is also used for the second polarizing member. Is preferable. The polarization direction of the second polarizing member is preferably an angle of 90 ° with respect to the polarization direction of the first polarizing member.

When the first polarizing member is a circular polarizing plate, it is preferable to use a circular polarizing plate for the second polarizing member as well. The circularly polarizing plate includes a right-handed circularly polarizing plate and a left-handed circularly polarizing plate. When one is a right-handed polarizing plate, the other is preferably a left-handed polarizing plate.

<Reflective member>
The detection member of the present embodiment may include a reflection member. Specifically, as shown in FIGS. 5 and 6, when the light emitting member (reference numeral 18) and the light receiving member (reference numeral 20) are close to each other, the detecting member includes a reflecting member. The reflective member (reference numeral 72) is a component that emits light emitted from the light emitting member and passes through the pressure detecting member, reflects the light toward the pressure detecting member side, passes the pressure detecting member again, and causes the light receiving member to receive light. The reflective member is preferably formed of a material that reflects light without scattering, and the reflective member includes a metal plate, a glass plate coated with a metal thin film, and a resin film coated with a metal thin film. A retroreflective member or the like is used.

When a reflective member is used, as shown in FIGS. 5 and 6, the number of polarizing members may be one (one type). The phase difference of the polarized light reflected by the reflecting member changes by 180 °. Specifically, in the case of linearly polarized light, the angle of polarization is rotated by 90 °. Further, in the case of circularly polarized light, the rotation direction of circularly polarized light is reversed. Therefore, the incident light incident on the pressure detecting member cannot return to the light receiving member unless birefringence occurs inside the pressure detecting member, and the light receiving amount increases according to the pressure.

<First light guide member, second light guide member>
The detection member of the present embodiment may include a first light guide member and a second light guide member. Specifically, as shown in FIG. 6, when the light emitting member and the light receiving member are in close proximity to each other, the detection member includes a first light guide member (reference numeral 82) and a second light guide member (reference numeral 84). To prepare for.

The first light guide member (optical fiber) is a member that guides the light emitted from the light emitting member to the polarizing member. The second light guide member (optical fiber) is a member that guides the light that has passed through the polarizing member to the light receiving component. The first light guide member and the second light guide member are not particularly limited as long as they are optical fibers, and glass or resin optical fibers may be used for the first light guide member and the second light guide member. can.

<Contact member>
The detection member of this embodiment may include a contact member. The contact member is a member that transmits uniform pressure to the pressure detecting member. Further, as shown in FIGS. 2 and 4, in the contact member (reference numeral 42), the gripping object (see reference numeral 200 in FIGS. 10 and 11), which is a measurement target component, comes into contact with any part of the contact member. Is also arranged so that the force is transmitted to the pressure detecting member.

Further, as shown in FIG. 11, since the gripping object does not come into direct contact with the pressure detecting member (reference numeral 54), it is possible to prevent the pressure detecting member from being damaged or soiled.

However, the gripping object may be brought into direct contact with the pressure detecting member without using the contact member. As a result, contact with the gripping object may be detected with high sensitivity. When the contact member is not used, the plate surface of the pressure detection member may be curved so that the central portion of the pressure detection member comes into contact with the gripping object instead of a flat surface. can. Even if the plate surface of the pressure detecting member is a curved surface, the light from the light emitting member propagates to the light receiving member along the curved surface of the pressure detecting member, and the pressure can be detected.

<Sliding force detection member>
The detection member of the present embodiment is provided with a shear force detection member. The shear force detecting member is a member that detects the shear stress generated in the pressure detecting member. The shear force detecting member may be embedded inside the pressure detecting member, or may be embedded inside a cushioning member (see reference numeral 56 in FIGS. 3 to 6) in contact with the pressure detecting member.

The shear force detecting member may be arranged so as to be able to detect the shear stress applied to the pressure detecting member (shear force applied in the X-axis direction or the Y-axis direction in FIG. 1), and the shape is not particularly limited. .. However, from the viewpoint of ease of arrangement, the shear force detecting member is preferably long (for example, ribbon-shaped, linear, thin-film-shaped).

As the shear force detecting member, it is preferable to use a rod-shaped member having a long conductor and a long piezoelectric body spirally wound in one direction with respect to the conductor.

Hereinafter, a long conductor (hereinafter referred to as “conductor”) and a long piezoelectric body (hereinafter referred to as “piezoelectric body”) included in the preferred form of the shear force detecting member will be described.

(conductor)
The conductor (for example, an internal conductor) is preferably a signal line conductor.
The signal line conductor is a conductor for efficiently detecting an electric signal from a piezoelectric material. Specifically, it is a conductor for detecting a voltage signal (charge signal) corresponding to the applied tension when a tension is applied to the shear force detecting member.

The conductor is preferably a good electrical conductor, for example, copper wire, aluminum wire, SUS wire, metal wire coated with an insulating film, carbon fiber, resin fiber integrated with carbon fiber, brocade wire, organic conductive wire. It is possible to use materials and the like. Kinshi wire is a fiber wound with copper foil in a spiral.

(Piezoelectric material)
The piezoelectric material preferably contains an organic piezoelectric material.
Examples of the organic piezoelectric material include polyvinylidene fluoride (PVDF), a helical chiral polymer having optical activity, silk fiber and the like. Among them, a helical chiral polymer having optical activity is preferable, and polylactic acid (PLA) is particularly preferable.

Hereinafter, the helical chiral polymer having optical activity is referred to as a helical chiral polymer (A).
When the piezoelectric material contains a helical chiral polymer (A) having optical activity as an organic piezoelectric material, the helical chiral polymer (A) has an optical purity of 95.00% ee or more from the viewpoint of further improving the piezoelectricity. It is preferable to have.

Further, the helical chiral polymer (A) is preferably composed of a D-form or an L-form from the viewpoint of further improving the piezoelectricity.
The content of the helical chiral polymer (A) is preferably 80% by mass or more with respect to the total amount of the piezoelectric material from the viewpoint of further improving the piezoelectricity.

(Preferable mode of shear force detecting member)
It is preferable that the shear force detecting member includes a long conductor and a long piezoelectric body spirally wound in one direction with respect to the conductor, and the piezoelectric body contains an organic piezoelectric material.
Specific preferred embodiments of the shear force detecting member include the following embodiments A to T.

-Aspect A-
The shear force detecting member comprises a long conductor and a long first piezoelectric body spirally wound in one direction with respect to the conductor.
The first piezoelectric material contains a helical chiral polymer (A) having optical activity, and contains the helical chiral polymer (A).
The length direction of the first piezoelectric body and the main orientation direction of the helical chiral polymer (A) contained in the first piezoelectric body are substantially parallel to each other.
An embodiment in which the degree of orientation F of the first piezoelectric body obtained from the X-ray diffraction measurement by the following formula (a) is in the range of 0.5 or more and less than 1.0.
Degree of orientation F = (180 ° -α) / 180 ° ... (a)
α represents the half width (unit: °) of the peak derived from orientation.

-Aspect B-
In the shear force detection member of aspect A,
The conductor is an internal conductor,
An embodiment in which the first piezoelectric body is spirally wound in one direction along the outer peripheral surface of the inner conductor.

-Aspect C-
In the shear force detection member of aspect B,
Further, a long second piezoelectric body spirally wound in a direction different from the one direction is provided.
The second piezoelectric material contains a helical chiral polymer (A) having optical activity, and contains the helical chiral polymer (A).
The length direction of the second piezoelectric body and the main orientation direction of the helical chiral polymer (A) contained in the second piezoelectric body are substantially parallel.
The degree of orientation F of the second piezoelectric body obtained by the formula (a) from the X-ray diffraction measurement is in the range of 0.5 or more and less than 1.0.
An embodiment in which the chirality of the helical chiral polymer (A) contained in the first piezoelectric body and the chirality of the helical chiral polymer (A) contained in the second piezoelectric body are different from each other.

-Aspect D-
In the shear force detection member of aspect B,
Further, a first insulator spirally wound along the outer peripheral surface of the inner conductor is provided.
An embodiment in which the first insulator is arranged on the side opposite to the inner conductor when viewed from the first piezoelectric body.

-Aspect E-
In the shear force detection member of aspect B,
Further, a first insulator spirally wound along the outer peripheral surface of the inner conductor is provided.
An embodiment in which the first insulator is arranged between the inner conductor and the first piezoelectric body.

-Aspect F-
In the shear force detection member of aspect B,
Further, it is provided with a long second piezoelectric body wound in a direction different from the one direction.
The second piezoelectric material contains a helical chiral polymer (A) having optical activity, and contains the helical chiral polymer (A).
The length direction of the second piezoelectric body and the main orientation direction of the helical chiral polymer (A) contained in the second piezoelectric body are substantially parallel.
The degree of orientation F of the second piezoelectric body obtained by the formula (a) from the X-ray diffraction measurement is in the range of 0.5 or more and less than 1.0.
The first piezoelectric body and the second piezoelectric body form a braided structure that is alternately intersected with each other.
An embodiment in which the chirality of the helical chiral polymer (A) contained in the first piezoelectric body and the chirality of the helical chiral polymer (A) contained in the second piezoelectric body are different from each other.

-Aspect G-
In the shear force detection member of aspect B,
Further, a first insulator wound along the outer peripheral surface of the inner conductor is provided.
An embodiment in which the first piezoelectric body and the first insulator form a braided structure that is alternately intersected with each other.

-Aspect H-
In any one of the shear force detecting members of Aspects B to G,
An embodiment in which the first piezoelectric body is wound while maintaining an angle of 15 ° to 75 ° with respect to the axial direction of the internal conductor.

-Aspect I-
In any one of the shear force detecting members of Aspects B to H,
The first piezoelectric body has a fiber shape consisting of a single or a plurality of bundles, and has a fiber shape.
An embodiment in which the major axis diameter of the cross section of the first piezoelectric body is 0.0001 mm to 10 mm.

-Aspect J-
In any one of the shear force detection members A to H,
The first piezoelectric body has a long flat plate shape and has a long flat plate shape.
The thickness of the first piezoelectric body is 0.001 mm to 0.2 mm, and the thickness is 0.001 mm to 0.2 mm.
The width of the first piezoelectric body is 0.1 mm to 30 mm, and the width thereof is 0.1 mm to 30 mm.
An embodiment in which the ratio of the width of the first piezoelectric body to the thickness of the first piezoelectric body is 2 or more.
The first piezoelectric body in the aspect J preferably has a long flat plate shape.
The "main surface" of the long flat plate-shaped piezoelectric body means a surface orthogonal to the thickness direction of the long flat plate-shaped piezoelectric body (in other words, a surface including the length direction and the width direction).

-Aspect K-
In any one of the shear force detecting members A to J,
The first piezoelectric material comprises a stabilizer (B) having one or more functional groups selected from the group consisting of a carbodiimide group, an epoxy group, and an isocyanate group and having a weight average molecular weight of 200 to 60,000, and the helical chiral. A embodiment containing 0.01 parts by mass to 10 parts by mass with respect to 100 parts by mass of the polymer (A).

-Aspect L-
In the shear force detection member of aspect K,
Further, an embodiment including a functional layer arranged on the side of at least one main surface of the first piezoelectric body.

-Aspect M-
In the shear force detection member of aspect L,
An embodiment in which the functional layer includes at least one of an easy-adhesion layer, a hard coat layer, an antistatic layer, an anti-block layer, a protective layer, and an electrode layer.

-Aspect N-
In the shear force detection member of aspect L or aspect M,
A mode in which the functional layer includes an electrode layer.

-Aspect O-
In the shear force detection member of aspect N,
An embodiment in which at least one of the surface layers of the laminate including the first piezoelectric body and the functional layer is the electrode layer.

-Aspect P-
In the shear force detection member of aspect A,
An embodiment in which the conductor and the first piezoelectric body are twisted together.

-Aspect Q-
In the shear force detection member of aspect P,
The first piezoelectric body has a fiber shape consisting of a single or a plurality of bundles, and has a fiber shape.
An embodiment in which the major axis diameter of the cross section of the first piezoelectric body is 0.0001 mm to 2 mm.

-Aspect R-
In any one of the shear force detecting members A to Q,
An embodiment in which the conductor is a brocade wire.

-Aspect S-
In any one of the shear force detecting members of A to R,
An embodiment in which an adhesive layer is provided between the conductor and the first piezoelectric body.

-Aspect T-
In any one of the shear force detecting members of Aspects A to S,
An embodiment in which the helical chiral polymer (A) contained in the first piezoelectric body is a polylactic acid-based polymer having a main chain containing a repeating unit represented by the following formula (1).

In the shear force detecting member of the preferred embodiment (Aspects A to T), the first piezoelectric body and the second piezoelectric body are piezoelectric bodies containing the helical chiral polymer (A) having optical activity. The first piezoelectric body and the second piezoelectric body may be the same or different. However, the chirality of the helical chiral polymer (A) contained in the first piezoelectric body and the second piezoelectric body is preferably selected as appropriate from the viewpoint of improving the piezoelectric sensitivity and the piezoelectric output.

Further, the first insulator is not particularly limited. The shape of the first insulator is preferably a long shape from the viewpoint of ease of winding with respect to the conductor.

In the shear force detecting member of the above preferred embodiment, the first piezoelectric body contains the helical chiral polymer (A), and the length direction of the first piezoelectric body and the main orientation direction of the helical chiral polymer (A) are different. Piezoelectricity is exhibited by being substantially parallel and having the degree of orientation F of the first piezoelectric body F of 0.5 or more and less than 1.0.

On top of that, the shear force detecting member of the preferred embodiment has a configuration in which the first piezoelectric body is spirally wound in one direction with respect to the conductor.

In the shearing force detecting member of the above preferred embodiment, by arranging the first piezoelectric body as described above, when tension (stress) acts in the length direction of the shearing force detecting member, the helical chiral polymer (A). ) Is applied with a shearing force, and the helical chiral polymer (A) is polarized in the radial direction of the shearing force detecting member. The polarization direction is the plane of the constituent minute regions when the first piezoelectric body wound in a spiral shape is regarded as an aggregate of minute regions that can be regarded as a plane in the length direction thereof. In addition, when a shearing force due to tension (stress) acts on the helical chiral polymer, it substantially coincides with the direction of the electric field generated due to the piezoelectric stress constant d14.

Specifically, for example, in polylactic acid, in the case of an L-lactic homopolymer (PLLA) whose molecular structure is a left-handed spiral structure, a first piezoelectric body whose main orientation direction and length direction of PLLA are substantially parallel to each other is used. When tension (stress) acts on a structure that is spirally wound to the left with respect to the conductor, an electric field (outward) from the center of the circle in a circular cross section parallel to the tension and perpendicular to the tension ( Polarization) occurs. On the contrary, tension (stress) is applied to the structure in which the first piezoelectric body whose length direction is substantially parallel to the main orientation direction of PLLA is wound in a right-handed spiral with respect to the conductor. When acted, an electric field (polarization) is generated from the outside to the center of the circle having a circular cross section perpendicular to the tension in the radial direction.

Further, for example, in the case of a D-lactic acid homopolymer (PDLA) whose molecular structure is a right-handed spiral structure, a first piezoelectric material whose length direction is substantially parallel to the main orientation direction of PDLA is attached to the conductor. When tension (stress) acts on a structure spirally wound to the left, an electric field (polarization) is generated from the outside to the center of a circle having a circular cross section perpendicular to the tension in the radial direction. On the contrary, tension (stress) is applied to the structure in which the first piezoelectric body whose length direction is substantially parallel to the main orientation direction of PDLA is wound in a right-handed spiral with respect to the conductor. When acted, an electric field (polarization) is generated from the center of the circle having a circular cross section perpendicular to the tension in the radial direction.

As a result, when tension acts in the length direction of the shear force detecting member, a potential difference proportional to the tension is generated in a phase-aligned state at each part of the first piezoelectric body arranged in a spiral shape. It is considered that a voltage signal proportional to the tension is effectively detected.

Therefore, according to the shearing force detecting member of the above preferred embodiment, a shearing force detecting member having excellent piezoelectric sensitivity and excellent stability of the piezoelectric output can be obtained.

In particular, the shear force detection member using a non-pyroelectric polylactic acid-based polymer as the helical chiral polymer (A) has more stable piezoelectric sensitivity than the shear force detection member using pyroelectric PVDF. , And the stability of the piezoelectric output (stability with time or temperature change) is further improved.

Here, the fact that the length direction of the first piezoelectric body and the main orientation direction of the helical chiral polymer (A) are substantially parallel means that the first piezoelectric body is strong in tension in the length direction ( That is, it has an advantage of excellent tensile strength in the length direction). Therefore, even if the first piezoelectric body is spirally wound in one direction with respect to the conductor, it is difficult to break.

Further, the fact that the length direction of the first piezoelectric body and the main orientation direction of the helical chiral polymer (A) are substantially parallel means that, for example, the stretched piezoelectric film is slit to form the first piezoelectric body. It is also advantageous in terms of productivity when obtaining (for example, a slit ribbon).

"Approximately parallel" means that the angle formed by the two line segments is 0 ° or more and less than 30 ° (preferably 0 ° or more and 22.5 ° or less, more preferably 0 ° or more and 10 ° or less, still more preferably 0 ° or more. It means that it is 5 ° or less, particularly preferably 0 ° or more and 3 ° or less).

Further, the main orientation direction of the helical chiral polymer (A) means the main orientation direction of the helical chiral polymer (A). The main orientation direction of the helical chiral polymer (A) can be confirmed by measuring the degree of orientation F of the first piezoelectric body.

Further, when the raw material is melt-spun and then stretched to produce a first piezoelectric body, the main orientation direction of the helical chiral polymer (A) in the manufactured first piezoelectric body is the main stretching direction. means. The main stretching direction refers to the stretching direction.

Similarly, when the first piezoelectric body is manufactured by stretching the film and forming slits in the stretched film, the main orientation direction of the helical chiral polymer (A) in the manufactured first piezoelectric body is mainly. It means the stretching direction. Here, the main stretching direction refers to the stretching direction in the case of uniaxial stretching, and refers to the stretching direction having the higher stretching ratio in the case of biaxial stretching.

In the shear force detecting member of the above preferred embodiment, the elongated conductor is an internal conductor, and the elongated first piezoelectric body is spirally wound in one direction along the outer peripheral surface of the internal conductor. It is preferable to have.

By using the inner conductor as the conductor, the first piezoelectric body can be easily arranged spirally in one direction while maintaining the spiral angle β with respect to the axial direction of the inner conductor.
The "spiral angle β" means an angle formed by the axial direction of the conductor and the direction in which the first piezoelectric body is arranged (the length direction of the first piezoelectric body) with respect to the axial direction of the conductor.

As a result, for example, when tension acts in the length direction of the shear force detecting member, the polarization of the helical chiral polymer (A) tends to occur in the radial direction of the shearing force detecting member. As a result, a voltage signal (charge signal) effectively proportional to the tension is detected.

Further, since the shear force detecting member of the preferred embodiment (however, embodiments B to O and aspects R to T) can have the same structure as the internal structure (internal conductor and dielectric) provided in the coaxial cable, for example, the above. When the shear force detecting member is applied to a coaxial cable, it can have a structure having high electromagnetic shielding properties and resistance to noise.

(Arrangement of shear force detection member)
As shown in FIGS. 1 to 6, if the elongated shear force detecting member is arranged along the plate surface of the pressure detecting member, the shape of the shearing force detecting member is not particularly limited. There is no. As an example, FIG. 7 shows the arrangement of the shear force detecting member when viewed from the Z-axis direction.

<Cushioning member>
The detection member of this embodiment may include a cushioning member. The cushioning member is made of an elastic material and is a member that transmits the shear stress generated in the pressure detecting member to the shearing force detecting member. As shown in FIGS. 3 to 6, the cushioning member (reference numeral 56) is used when the shear force detecting member is not embedded inside the pressure detecting member. Here, the "elastic material" is a material having an asker hardness of 50 degrees or less.

Specifically, the cushioning member is arranged so as to be in surface contact with the plate surface (XY plane) formed on the pressure detecting member, and the shear force detecting member is embedded inside the cushioning member. As a result, the cushioning member can propagate the shearing force parallel to the XY plane generated in the pressure detecting member to the shearing force detecting member.

The material of the cushioning member is not particularly limited, and a gel-like or sponge-like material may be used. The material of the cushioning member may be any material that can deform itself in the shearing direction by receiving the shearing force generated in the pressure detecting member and propagate the shearing force to the shearing force detecting member. Further, when the cushioning member is used, the pressure detecting member can be manufactured separately from the shear force detecting member, which is advantageous in manufacturing.

[Specific example of detection member]
Specific examples of the detection member will be described with reference to FIGS. 1 to 6. The arrow X shown in the figure indicates the vertical direction (vertical direction) of the member, the arrow Y indicates the width direction (horizontal direction) of the member, and the arrow Z indicates the depth direction (horizontal direction) of the member. Further, the present embodiment is not limited to the following specific examples.

<Detection member according to the first specific example>
First, the detection member 10 according to the first specific example will be described. As shown in FIG. 1, the detection member 10 includes a pressure detection member 14 mounted on the upper surface of a plate-shaped base material 12, a light emitting member 18, a light receiving member 20, a first polarizing member 24, and a second. A polarizing member 26 and a shear force detecting member 32 are provided.

The pressure detecting member 14 has a thick plate shape in which the plate surface faces the depth direction, and extends in the width direction. The light emitting member 18 and the light receiving member 20 are arranged so as to sandwich the pressure detecting member 14 from the width direction. The light emitting member 18 is arranged on one side in the width direction (left side in the figure) with respect to the pressure detecting member 14, and the light receiving member 20 is arranged on the other side in the width direction (right side in the figure) with respect to the pressure detecting member 14. Is located in. Further, the first polarizing member 24 is arranged between the light emitting member 18 and the pressure detecting member 14 in the width direction, and the second polarizing member 26 is arranged with the light receiving member 20 and the pressure detecting member 14 in the width direction. It is placed between. Further, the shear force detecting member 32 has a long shape extending in the width direction. Further, the shear force detecting member 32 is arranged inside the pressure detecting member 14 and along the plate surface of the pressure detecting member 14, and a part of the shearing force detecting member 32 is the width of the pressure detecting member 14. It protrudes from the other end in the direction.

As shown in FIGS. 7A, 7B, C), D, and E, the shear force detecting member 32 can be arranged in various ways when viewed from the depth direction (Z-axis direction). However, the present invention is not limited thereto.

In this configuration, the light emitted from the light emitting member 18 passes through the first polarizing member 24, the pressure detecting member 14, and the second polarizing member 26 in this order, and is received by the light receiving member 20.

<Detection member according to the second specific example>
Next, the detection member 40 according to the second specific example will be described. The part of the detection member 40 that is different from the detection member 10 will be mainly described. As shown in FIG. 2, the detection member 40 includes a contact member 42.

The contact member 42 is arranged so as to make surface contact with the plate surface 14a of the pressure detecting member 14. Specifically, the contact member 42 has a plate surface 42a in contact with the plate surface 14a of the pressure detecting member 14 and a plate surface 42b facing the opposite side.

<Detection member according to the third specific example>
Next, the detection member 50 according to the third specific example will be described. The part of the detection member 50 that is different from the detection member 10 will be mainly described. As shown in FIG. 3, the detection member 50 includes a pressure detection member 54 and a cushioning member 56.

The pressure detection member 54 is thinner in the depth direction than the pressure detection member 14 (see FIG. 1) of the detection member 10. The cushioning member 56 has a plate shape whose plate surface faces in the depth direction, and is arranged between the base material 12 and the pressure detecting member 54 in the depth direction.

Further, the shear force detecting member 32 is embedded inside the cushioning member 56, and a part of the shearing force detecting member 32 protrudes from the other end of the cushioning member 56 in the width direction.

<Detection member according to the fourth specific example>
Next, the detection member 60 according to the fourth specific example will be described. The part of the detection member 60 that is different from the detection member 50 will be mainly described. As shown in FIG. 4, the detection member 60 includes a contact member 42.

The contact member 42 is arranged so as to come into contact with the plate surface 54a of the pressure detecting member 54. Specifically, the contact member 42 has a plate surface 42a in contact with the plate surface 54a of the pressure detecting member 54, and a plate surface 42b facing the opposite side.

<Detection member according to the fifth specific example>
Next, the detection member 70 according to the fifth specific example will be described. The part of the detection member 70 that is different from the detection member 10 will be mainly described. As shown in FIG. 5, the detection member 70 includes a cushioning member 56, a reflecting member 72, and a polarizing member 74.

The cushioning member 56 has a plate shape whose plate surface faces in the depth direction, and is arranged between the base material 12 and the pressure detecting member 14 in the depth direction. Further, the shear force detecting member 32 is embedded inside the cushioning member 56, and a part of the shearing force detecting member 32 protrudes from the other end of the cushioning member 56 in the width direction.

The light emitting member 18 and the light receiving member 20 are arranged on the other end side in the width direction with respect to the pressure detecting member 14. Further, the light emitting member 18 and the light receiving member 20 are arranged side by side in the depth direction.

The reflective member 72 is arranged on the opposite side of the light emitting member 18 and the light receiving member 20 with the pressure detecting member 14 interposed therebetween. Further, the polarizing member 74 is arranged between the light emitting member 18 and the light receiving member 20 and the pressure detecting member 14 in the width direction.

In this configuration, the light emitted from the light emitting member 18 passes through the polarizing member 74 and the pressure detecting member 14, is reflected by the reflecting member 72, passes through the pressure detecting member 14 and the polarizing member 74 again, and passes through the light receiving member. Light is received by 20. As a result, the optical path L of light becomes V-shaped.

<Detection member according to the sixth specific example>
Next, the detection member 80 according to the sixth specific example will be described. The part of the detection member 80 that is different from the detection member 70 will be mainly described. As shown in FIG. 6, the detection member 80 includes a first light guide member 82 and a second light guide member 84. The first light guide member 82 is arranged between the polarizing member 74 and the light emitting member 18 in the width direction, and the second light guide member 84 is located between the polarizing member 74 and the light receiving member 20 in the width direction. Is located in.

[Action of detection member]
Next, the actions of the detection members 10, 40, 50, 60, 70, 80 (hereinafter, “detection members 10 to 80”) will be described. The following actions 1 and 2 occur in the detection members 10 to 80.

<Action 1>
When a force in the direction perpendicular to the plate surface of the pressure detecting members 14 and 54 is applied to the pressure detecting members 14 and 54 of the detecting members 10 to 80, the inside of the photoelastic urethane resin of the pressure detecting members 14 and 54 Birefringence occurs due to photoelasticity. Then, the light emitted from the light emitting member 18 is incident on the pressure detecting members 14 and 54. Polarized light (linearly polarized light or circularly polarized light) as light (light rays) incident on the pressure detecting members 14 and 54 and traveling in the width direction (Y-axis direction) has a difference in propagation speed inside the photoelastic urethane resin. Then, the phase difference between the wave of the electric vector of the Z-axis component and the wave of the electric vector of the X-axis component changes. As a result, the amount of light that can pass through the second polarizing member 26 or the polarizing member 74 changes, and the intensity of the light detected by the light receiving member 20 changes.

<Action 2>
When a force along the plate surface of the pressure detecting members 14 and 54 is applied to the pressure detecting members 14 and 54 of the detecting members 10 to 80, the applied force is transmitted to the shearing force detecting member 32 to detect the shearing force. Tension is generated in the member 32. Then, a shearing force is applied to the organic piezoelectric material (for example, a helical chiral polymer) contained in the shearing force detecting member 32, and the shearing force causes polarization of the organic piezoelectric material in the radial direction of the shearing force detecting member 32. Further, the polarization of the organic piezoelectric material causes a charge (electric field) proportional to the tension to be generated by the piezoelectric effect. By taking this out as a voltage signal, the shear force is detected.

<Concrete configuration>
Next, a specific configuration of the detection member will be described with reference to FIGS. 8A and 8B. It should be noted that this specific configuration embodies the detection member 60 (see FIG. 4) according to the fourth specific example.

As shown in FIGS. 8A and 8B, inside the resin detection member case 100, an infrared laser as a light emitting member 18, a linear polarizing element as a first polarizing member 24, and a pressure detecting member A photoelastic urethane as 54 and a linear polarizing element as a second polarizing member 26 are arranged. Further, inside the detection member case 100 (hereinafter referred to as “case 100”), a photodiode as a light receiving member 20, a piezoelectric line as a shear force detection member 32, and a layer of an elastic adhesive as a cushioning member 56 are formed. Have been placed.

Further, a contact member 42 partially arranged outside the case 100 is provided. The contact member 42 includes a plate-shaped contact portion 42c that comes into contact with the photoelastic urethane resin as the pressure detecting member 54, a plate-shaped support portion 42d arranged outside the case 100, and a contact portion 42c and a support portion 42d. It has a connecting portion 42e for connecting the above. The plate surface of the contact portion 42c and the plate surface of the support portion 42d face in the depth direction.

The first polarizing member 24 is arranged so that the polarization direction of the first polarizing member 24 is arranged on the xy plane and tilted by 45 °. Further, the second polarizing member 26 is arranged so that the polarization direction of the second polarizing member 26 is tilted by 90 ° with respect to the polarization direction of the first polarizing member 24.

The length of the photoelastic urethane resin as the pressure detecting member 54 in the width direction (L1 in the figure) is 30 mm, and the length of the photoelastic urethane resin in the depth direction (L2 in the figure) is 3 mm. The length of this photoelastic urethane resin in the vertical direction (L3 in the figure) is 10 mm. Further, the length of the case 100 in the width direction (L4 in the figure) is 60 mm, the length of the case 100 in the depth direction (L5 in the figure) is 15 mm, and the length of the case 100 in the vertical direction (FIG. Medium L6) is set to 20 mm. Further, the distance in the depth direction (L7 in the figure) from the end of the case 100 to the end of the contact member 42 is 22 mm.

When a detection member having this specific configuration is used in an experiment, a DC power supply is connected to the wiring of the infrared laser as the light emitting member 18, and a detection circuit is connected to the wiring of the photodiode as the light receiving member 20 to detect the shear force. An amplifier circuit is connected to the wiring of the piezoelectric line as the member 32.

<Robot hand>
Next, the robot hand provided with the detection member 60 (see FIG. 4) according to the fourth specific example will be described with reference to FIGS. 10 and 11.

As shown in FIG. 10, the robot hand 150 is a joint that supports a pair of finger portions 152, 154 and a pair of finger portions 152, 154 that are separated in the depth direction, and a pair of finger portions 152, 154 that are separated from each other in close proximity to each other. It is provided with a unit 158. Further, the robot hand 150 includes an arm portion 160 having one end connected to the joint portion 158.

The finger portions 152 and 154 extend in the width direction, and the joint portion 158 supports the finger portion 152 at one end and the finger portion 154 at the other end. The joint portion 158 is provided with a drive mechanism (not shown) so that the pair of finger portions 152 and 154 are brought close to each other. Further, the arm portion 160 is provided with a drive mechanism (not shown) so as to move the pair of finger portions 152, 154 and the joint portion 158.

Further, the detection member 60 is attached to the finger portion 154 so that the contact member 42 of the detection member 60 and the finger portion 152 are separated from each other in the depth direction.

Then, with the gripping object 200, which is a PET bottle, placed on the floor F (see FIG. 12), the robot hand is brought close to the pair of finger portions 152 and 154 as shown in FIGS. 10 and 11. The 150 is designed to grip the gripping object 200. Further, when the robot hand 150 grips the gripping object 200, a force in the depth direction (Z-axis direction) is applied to the detection member 60, and the detection member 60 is loaded on the gripping object 200 using the pressure detecting member 54. It is designed to detect the force.

Further, when the robot hand 150 tries to lift the gripping object 200, a force (sliding force) in the vertical direction (X-axis direction) or the width direction (Y-axis direction) is applied to the detection member 60, and the detection member 60 is loaded. Is adapted to detect the force applied to the gripping object 200 by using the shear force detecting member 32.

Here, if the gripping object 200 is incompletely gripped by the robot hand 150, the gripping object 200 may slip off from the robot hand 150. In such a case, the force in the vertical direction or the width direction detected by the detection member 60 fluctuates intermittently with the passage of time. In other words, the shear force (shear stress) fluctuates intermittently over time. The detection member 60 is adapted to continuously detect the intermittent fluctuation of the shear force by using the shear force detecting member 32.

In this way, by performing the detection (measurement) by the pressure detecting member 54 and the detection (measurement) by the shear force detecting member 32 almost at the same time, it can be determined whether or not the robot hand 150 can grip the gripping object 200. The robot hand 150 itself can make a judgment.

<Use of detection member>
Next, the use of the detection member will be described. The detection member of the present embodiment is a pressure-sensitive sensor that can simultaneously detect the force (pressure, impact) applied to the measurement object (grasping object 200) and the minute vibration generated by the dynamic friction between the measurement object and the detection member. Can be used as.

For example, when the gripping object 200 is gripped, lifted, and moved to another place by the robot hand 150 described above, the detection member can be used as a sensor for detecting the gripping state of the gripping object 200.

Further, the detection member of the present embodiment can be used as a bumper with a collision detection sensor such as a robot in combination with the cushion material. Further, by installing the detection member of the present embodiment inside the bed or the inside of the seat of a car or the like, the detection member can be used as a sensor for simultaneously detecting the biological reaction between the weight shift of the human body and respiration. can.

<Example>
Next, an example according to this embodiment will be described. The examples of this embodiment are not limited to the examples described below. In addition, "part" and "%" are based on mass unless otherwise specified. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, parameters, etc. used in the following description are the compounding ratios corresponding to them described in the above-mentioned "form for carrying out the invention" (forms for carrying out the invention). Substitute the upper limit value (value defined as "less than or equal to" or "less than") or the lower limit value (value defined as "greater than or equal to" or "excess") such as content ratio), physical property value, parameter, etc. be able to.

(Raw material of photoelastic polyurethane resin as pressure detection member)
First, a raw material of a photoelastic polyurethane resin as a pressure detecting member will be described.
A. High molecular weight polyol PTG-1000 (polytetramethylene ether glycol, hydroxyl value 111.5 mgKOH / g, manufactured by Hodogaya Chemical Co., Ltd.)
B. Low molecular weight polyol Trimethylolpropane (genuine chemical reagent)
C. Isocyanate (1) 3,3'-dimethylbiphenyl-4,4'-diisocyanate (TODI, manufactured by Nippon Soda)
(2) 4,4'-Diphenylmethane diisocyanate (MDI-PH, manufactured by Mitsui Chemicals, Inc.)
D. Additives Antioxidants (Hindered Phenolic Antioxidants)

(Manufacturing of photoelastic polyurethane resin as a pressure detection member)
Next, the production of a photoelastic polyurethane resin as a pressure detecting member will be described.

A glass flask is charged with 100 parts by mass of polytetramethylene ether glycol (PTG-1000) and 0.2 parts by mass of an antioxidant, dried under reduced pressure at 120 ° C. for 2 hours, lowered to 80 ° C., and nitrogen. It was returned to normal pressure.

Next, 9.2 parts by mass of 3,3'-dimethylbiphenyl-4,4'-diisocyanate was added while stirring, and the mixture was reacted for 4 hours.
Next, 1 part by mass of trimethylolpropane was added with stirring to adjust the temperature to 70 ° C.
Next, several drops of a defoaming agent were added, and 20.3 parts by mass of 4,4'-diphenylmethane diisocyanate dissolved at 70 ° C. was added, and the mixture was stirred and mixed.
Then, it was defoamed under reduced pressure for 30 seconds, returned to normal pressure with nitrogen, and then taken out from the flask to obtain a polyurethane composition.

Next, the obtained polyurethane composition was poured into a molding die (30 cm × 10 cm × 3 mm) and cured at 50 ° C. for 48 hours to obtain a photoelastic polyurethane resin sheet having a thickness of 3 mm.

This was cut into a length of 30 mm in length and 10 mm in width to obtain a photoelastic polyurethane resin as a pressure detecting member. The photoelastic constants and Young's modulus of the sheet material of this photoelastic polyurethane resin at 25 ° C. were measured and found to be 5000 × ^10-12 Pa ^-1 and 5.0 MPa, respectively. The glass transition temperature was measured by dynamic viscoelasticity measurement (frequency 10 Hz) and found to be -30 ° C.

(Manufacturing of ribbon-shaped piezoelectric body (slit ribbon) used for shear force detection member)
Next, the production of a ribbon-shaped piezoelectric body (slit ribbon) used for the shear force detecting member will be described.

Stabilizer [Stabaxol P400 (10 parts by mass) manufactured by Rheinchemy) with respect to 100 parts by mass of polylactic acid (product name: IngeoTM biopolymer, brand: 4032D) manufactured by NatureWorks LLC as a helical chiral polymer (an example of an organic piezoelectric material). , Stabaxol I (70 parts by mass) manufactured by Rheinchemy Co., Ltd., and Carbodilite LA-1 (20 parts by mass) manufactured by Nisshinbo Chemical Co., Ltd.] 1.0 part by mass was added and dry blended to prepare a raw material.

The prepared raw material was placed in an extruder hopper, extruded from a T die while being heated to 210 ° C., and contacted with a cast roll at 50 ° C. for 0.3 minutes to form a film of a precrystallized sheet having a thickness of 150 μm ( Preliminary crystallization step). The crystallinity of the pre-crystallization sheet was measured and found to be 6%.

The obtained pre-crystallized sheet was started to be stretched at a stretching speed of 10 m / min by roll-to-roll while heating at 70 ° C., and uniaxially stretched in the MD direction up to 3.5 times (stretching step). The thickness of the obtained film was 49.2 μm.

Then, the uniaxially stretched film was brought into contact with a roll heated to 145 ° C. for 15 seconds by roll-to-roll and annealed, and then rapidly cooled to prepare a piezoelectric film (annealing step).

After that, the piezoelectric film was further slit by a slitting machine with a width of 0.6 mm so that the slitting direction and the stretching direction of the piezoelectric film were substantially parallel to each other. As a result, a slit ribbon having a width of 0.6 mm and a thickness of 49.2 μm was obtained as a ribbon-shaped piezoelectric body, and this was used as a ribbon-shaped piezoelectric body. The cross-sectional shape of the obtained slit ribbon was rectangular.

(Manufacturing a piezoelectric line as a shear force detection member)
Next, the production of the piezoelectric line as the shear force detecting member will be described.
First, as an internal conductor (signal wire conductor), Kinshi wire U24-01-00 (wire diameter 0.26 mm, length 250 mm) manufactured by Meisei Sangyo Co., Ltd. was prepared.

Next, the above-mentioned ribbon-shaped piezoelectric body (slit ribbon) having a width of 0.6 mm and a thickness of 49.2 μm is wound left around the brocade wire so as to face the direction of 45 ° with respect to the long axis direction of the brocade wire. (Spiral angle 45 °), the ribbon was wound in a spiral shape without any gap so that the ribbon could not be seen, and the ribbon was wrapped. "Left-handed" means that the ribbon-shaped piezoelectric material is wound left-handed from the front side to the back side of the brocade wire when viewed from one end in the axial direction of the brocade wire (internal conductor). ..

Next, a copper foil ribbon with an adhesive slit-cut to a width of 0.6 mm was prepared. This copper foil ribbon was wound around the ribbon-shaped piezoelectric body without a gap so as not to expose the ribbon-shaped piezoelectric body by the same method as the above-mentioned ribbon-shaped piezoelectric body, and the ribbon-shaped piezoelectric body was wrapped.
As described above, a piezoelectric line (an example of a shear force detecting member) was manufactured.

(Manufacturing of detection member)
Next, the production of a detection member having the same configuration as the detection member shown in FIGS. 8A and 8B will be described.
First, an infrared laser as a light emitting member 18, a first polarizing member 24, a second polarizing member 26, and a photodiode as a light receiving member 20 were arranged (attached) to the case 100.

Further, an elastic adhesive (Cemedine Super X (registered trademark (manufactured by Cemedine Co., Ltd.))) in which a piezoelectric line as a shear force detecting member 32 manufactured by the above-mentioned method is applied to the bottom of the case 100 to a thickness of 1 mm is applied. Fixed using. The elastic adhesive is the cushioning member 56.

Further, a sheet material of a photoelastic polyurethane resin having a size of 30 mm × 10 mm × 3 mm (hereinafter referred to as “photoelastic sheet”) as a pressure detecting member produced by the above-mentioned method was placed on a sufficiently solidified elastic adhesive.

A power cable (wiring) was connected to the red laser as the light emitting member 18, and electric power was applied from the power supply (DC3V). Further, a signal cable (wiring) was connected to the photodiode as the light receiving member 20, and this signal cable was connected to a general detection circuit using an operational amplifier. Further, a piezoelectric line as a shear force detecting member 32 was connected to a general amplifier circuit using an operational amplifier.

Next, the metal contact member 42 shown in FIGS. 8A and 8B was installed. In this way, the detection member was manufactured.

(Evaluation 1)
Next, an evaluation was performed using the manufactured detection member. The detection member was placed on the desk so that the contact member 42 was on the upper side, and a force was applied from above to below. The relationship between the applied force (N) and the voltage (V) detected from the light receiving member is shown in the graph of FIG. It can be seen that increasing the force increases the detected voltage. Specifically, the horizontal axis of the graph is the force applied to the pressure detecting member 54, and the vertical axis of the graph is the voltage detected by the photodiode. Since the voltage value on the vertical axis of the graph differs depending on the configuration of the detection circuit used for the measurement, it cannot be directly compared with the output on the vertical axis of the graphs of FIGS. 13 and 14, which will be described later, in absolute value.

(Evaluation 2)
Next, the evaluation was performed using the robot hand 150 (see FIG. 10) equipped with the manufactured detection member.
As shown in FIGS. 10 and 11, the robot hand 150 gripped the gripping object 200. As the object to be gripped 200, a PET bottle (400 g) containing a liquid and having an internal volume of 450 mL was used. The output from the detection member is input to the control unit (microcontroller), the control unit makes a judgment in steps S300, S500, and S700 of the flow chart shown in FIGS. 15 and 16, and the control unit determines based on the judgment result. A command signal is transmitted to the controller (drive system) of the robot hand 150.

-An example of operation-
Hereinafter, an example of the detection method executed by using the robot hand 150 will be described with reference to the flow charts shown in FIGS. 15 and 16. First, in the initial state (the number of grips is 0), as shown in FIG. 10, the finger portion 152 and the detection member 60 of the robot hand 150 and the gripping object 200 are separated from each other in the depth direction. In this state, the distance between the finger portion 152 and the detection member 60 (L10 in FIG. 10) is set to 100 mm. Further, the gripping object 200 is placed on the floor F (see FIG. 12).

When the operation is started, light is emitted by the red laser as the light emitting member 18. Then, in step S100 of the flow diagram shown in FIG. 15, the control unit moves the pair of finger portions 152 and 154 to cause the robot hand 150 to grip the gripping object 200 (see FIGS. 12A and 12B). .. Specifically, the control unit moves the pair of finger portions 152 and 154 until the interval between the pair of finger portions 152 and 154 becomes a predetermined predetermined interval. When the interval between the pair of finger portions 152 and 154 reaches the specified interval, the process proceeds to step S200.

In step S200, the control unit stops the pair of finger units 152 and 154 for 1 second. When the finger portions 152 and 154 stop for 1 second, the process proceeds to step S300.

In step S300, the control unit acquires the voltage detected by the photodiode as the light receiving member 20. Further, the control unit determines whether or not the acquired voltage is equal to or higher than the threshold value (0.5 V in this embodiment). If it is equal to or more than the threshold value, the process proceeds to step S400, and if it is less than the threshold value, the process proceeds to step S410.

In other words, if the control unit determines that the gripping object 200 is sufficiently gripped by the robot hand 150, the process proceeds to step S400, and the robot hand 150 controls that the gripping object 200 is not sufficiently gripped. If the unit determines, the process proceeds to step S410.

In step S400, the control unit moves the robot hand 150 upward (see FIGS. 12B and 12C). When the upward movement of the robot hand 150 starts, the process proceeds to step S500.

In step S500, the control unit acquires the voltage output by the piezoelectric line as the shear force detecting member 32 while the robot hand 150 is being moved upward. Further, the control unit determines whether the acquired voltage is within the threshold value (in this embodiment, the range from the median 2.15V to ± 0.75V), is larger than the threshold value, or is smaller than the threshold value. Although the piezoelectric line has outputs in both positive and negative directions, the control unit (microcontroller) may not be able to handle data of less than 0V. In this case, in consideration of this, the control unit determines whether the acquired voltage is within the threshold value, is larger than the threshold value, or is smaller than the threshold value. If it is within the threshold value, the process proceeds to step S600, and if it is larger than the threshold value or smaller than the threshold value, the process proceeds to step S610.

Specifically, when the gripping object 200 by the robot hand 150 is insufficiently gripped, the gripping object 200 slides off the robot hand 150 while the robot hand 150 is moving upward. When the gripping object 200 slides down from the robot hand 150, the force of the sliding applied to the detection member 60 fluctuates intermittently. Then, the piezoelectric line as the shear force detecting member 32 acquires this intermittently fluctuating voltage. When the amplitude of this fluctuation exceeds the threshold value, the control unit determines that the gripping object 200 has slipped off the robot hand 150, and in step S610 described later, the control unit moves the robot hand 150 downward. The gripping object 200 is placed on the floor F.

FIG. 13 is a graph showing the time-dependent change of the output of the shear force detecting member (solid line in the figure) and the time-dependent change of the output of the pressure detecting member (dotted line in the figure) in this series of operations. The vertical axis of this graph is the output voltage [V], and the horizontal axis is the elapsed time [S].

If the control unit determines that the gripping object 200 gripped by the robot hand 150 is not slipping, the process proceeds to step S600. On the other hand, if the gripping object 200 gripped by the robot hand 150 is slipping (sliding down), the control unit determines that the process proceeds to step S610.

In step S600, the control unit keeps the robot hand 150 moving upward, and stops the robot hand 150 when the robot hand 150 moves to a specified height (200 mm in this embodiment). When the robot hand 150 stops, the process proceeds to step S700.

In step S700, the control unit acquires the voltage detected by the photodiode as the light receiving member 20. Further, the control unit determines whether or not the acquired voltage is equal to or higher than the threshold value (0.5 V in this embodiment). If it is equal to or more than the threshold value, the process proceeds to step S800, and if it is less than the threshold value, the process proceeds to step S610.

In other words, if the control unit determines that the gripping object 200 is sufficiently gripped by the robot hand 150, the process proceeds to step S800, and the robot hand 150 controls that the gripping object 200 is not sufficiently gripped. If the unit determines, the process proceeds to step S610.

In step S800, the control unit moves the robot hand 150 horizontally by a predetermined distance, and then moves the robot hand 150 downward to place the gripping object 200 on the floor F at a target position. This ends a series of operations.

FIG. 14 is a graph showing the time-dependent change of the output of the shear force detecting member (solid line in the figure) and the time-dependent change of the output of the pressure detecting member (dotted line in the figure) in this series of operations. The vertical axis of this graph is the output voltage [V], and the horizontal axis is the elapsed time [S].

On the other hand, if the voltage acquired in step S300 is less than the threshold value, the process proceeds to step S410. In step S410, the control unit further moves the pair of finger portions 152 and 154 so that the distance between the pair of finger portions 152 and 154 becomes narrower. Specifically, the control unit narrows the distance (distance) between the pair of finger portions 152 and 154 by a specified amount (1 mm in this embodiment). That is, the control unit strongly grips the gripping object 200 by the robot hand 150. When the robot hand 150 strongly grips the gripping object 200, the process proceeds to step S200 and the above-mentioned steps are repeated.

If the voltage acquired in step S500 is larger than or smaller than the threshold value, or if the voltage acquired in step S700 is less than the threshold value, the process proceeds to step S610. In step S610, the control unit moves the robot hand 150 downward and puts the gripping object 200 on the floor F without moving the robot hand 150 in the horizontal direction (see FIGS. 12D and 12E). Further, the distance between the pair of fingers 152 and 154 is returned to the initial state (see FIGS. 12E and 12F). In other words, the control unit releases the gripping state of the gripping object 200 by the pair of finger portions 152 and 154. When the distance (distance) between the pair of finger portions 152 and 154 returns to the initial state, the process proceeds to step S710.

In step S710, the control unit moves the pair of finger portions 152 and 154 to cause the robot hand 150 to grip the gripping object 200. Specifically, the control unit sets this distance to a predetermined amount (1 mm in this embodiment) with respect to the distance (distance) between the pair of finger parts 152 and 154 in the state where the gripping object 200 was gripped immediately before. ) Is narrowed, and the robot hand 150 is made to grip the gripping object 200. In this way, the robot hand 150 is made to strongly grip the gripping object 200. When the robot hand 150 strongly grips the gripping object 200, the process proceeds to step S200 and the above-mentioned steps are repeated. Then, in step S800, the gripping object 200 is placed on the target position on the floor F, and a series of operations is completed.

(summary)
As described above, in the detection member 60, the force in the direction perpendicular to the plate surface of the plate-shaped pressure detecting member and the force in the direction along the plate surface of the plate-shaped pressure detecting member (sliding force). Can be detected. In other words, the detection member 60 can detect forces in two different directions with respect to the plate-shaped pressure detecting member.

Further, in the detection members 10 and 40, the shear force detection member 32 is embedded inside the pressure detection member 14. Therefore, the shearing force generated in the pressure detecting member 14 can be effectively detected as compared with the case where the shearing force detecting member is attached to the plate surface of the pressure detecting member.

Further, in the detection members 50, 60, 70, 80, the shear force detection member 32 is embedded inside the cushioning member 56 arranged so as to be in contact with the pressure detection member 14. Therefore, even when the plate-shaped pressure detecting member 14 is thin, the shear force detecting member 32 can be arranged by using the cushioning member 56.

Further, the polarization direction of the first polarizing member 24 forms an angle of 90 ° with respect to the polarization direction of the second polarizing member 26. As a result, the intensity of the light received by the light receiving member 20 can be sensitively changed according to the force applied to the pressure detecting member.

Further, in the robot hand 150, by using the robot hand 150, the gripping object 200 can be gripped and moved to a target position.

Further, in the method of detecting the gripping state, it is possible to detect the force of sandwiching the gripping object 200 by using the robot hand 150 and the sliding force generated between the gripping object 200 and the robot hand 150.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. That is clear to those skilled in the art. For example, in the above embodiment, the detection member 60 is attached to the robot hand 150, but the detection members 10, 40, 50, 70, 80 may be attached.

10 Detection member 14 Pressure detection member 18 Light emitting member 20 Light receiving member 24 First polarizing member (an example of another polarizing member)
26 Second polarizing member (example of polarizing member)
32 Slip force detection member 40 Detection member 50 Detection member 54 Pressure detection member 56 Cushioning member 60 Detection member 70 Detection member 74 Polarizing member 80 Detection member 150 Robot hand 152 Finger part 154 Finger part 200 Gripping object

Claims (9)

A pressure detection member formed in a plate shape using photoelastic polyurethane resin,
A light emitting member that is arranged to face the end face of the pressure detecting member and emits light toward the pressure detecting member.
A light receiving member that receives light emitted by the light emitting member and passed through the pressure detecting member.
A polarizing member arranged on an optical path of light passing through the pressure detecting member between the pressure detecting member and the light receiving member, and a polarizing member.
A shear force detecting member arranged along the plate surface of the pressure detecting member and outputting a detection signal corresponding to the shearing force acting on the pressure detecting member.
A detection member equipped with. The detection member according to claim 1, wherein the shear force detecting member is embedded inside the pressure detecting member. A cushioning member that comes into contact with the plate surface of the pressure detecting member and is formed of an elastic material is provided.
The detection member according to claim 1, wherein the shear force detecting member is embedded inside the cushioning member. Claims 1 to 3 include another polarizing member arranged between the pressure detecting member and the light emitting member and having a polarization direction at an angle of 90 ° with respect to the polarization direction of the polarizing member. The detection member according to any one item. 13. The detection member according to any one item. The detection member according to claim 5, wherein the shear force detecting member is formed in a rod shape. The photoelastic polyurethane resin forming the pressure detecting member has a Young's modulus of 2 MPa or more and 5 MPa or less at 25 ° C., and a photoelastic constant at 25 ° C. of 1000 × 10 ^-12 Pa ^-1 or more and 100,000 × 10 ^-12. The detection member according to any one of claims 1 to 6, which has a Pa- ¹ or less and a glass transition temperature of −60 ° C. or higher and -21 ° C. or lower. A pair of fingers that sandwich and grip the object to be gripped from both sides,
The detection member according to any one of claims 1 to 7, which is attached to one of the fingers so as to come into contact with the gripping object.
A robot hand equipped with. A detection method for detecting a gripping state when the gripping object is gripped and the gripping object is lifted by using the robot hand according to claim 8.
Based on the detection value detected by the light receiving member, the force for pinching the gripping object is detected, and based on the detection value detected by the shear force detecting member, the gripping object and the robot hand A detection method that detects the sliding force generated between the two.

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