KR102287736B1 - Actuator and display device comprising the same - Google Patents

Abstract

An actuator and a display device including the actuator are provided. The actuator of the present invention includes an electroactive layer comprising a dielectric elastomer and a ferroelectric filler, and a first transparent electrode and a second transparent electrode attached to both surfaces of the electroactive layer. The actuator according to an embodiment of the present invention has excellent light transmittance, so it is easy to be mounted on the front surface of the display panel, and the driving voltage is low, so it is easy to use in a mobile display or the like.

Description

Actuator and display device including the same

The present invention relates to an actuator and a display device including the actuator, and more particularly, to an actuator including an electroactive layer having excellent light transmittance and dielectric constant, and a display device including the same.

Recently, in response to the demand of users who want to conveniently use various display devices including liquid crystal displays and organic light emitting diodes, the use of a touch type display device in which a display device is touched and operated has become common.

Recently, in a touch-type display device, in addition to a technique for manipulating the display device, a technique related to an actuator has been introduced to reflect a user's intuitive experience on an interface and to feel a tactile feedback for a touch. In particular, since the conventional actuator is attached to the rear surface of the display panel, it is difficult to provide immediate and minute feedback to the user's touch. Therefore, by locating the actuator on the front surface of the display panel, research is being actively conducted to provide various and direct feedback sensitive to the user's touch.

In general, a conventional display device uses a vibration motor such as an eccentric motor (ERM) or a linear resonance motor (LRA) as an actuator. Since the vibration motor is designed to vibrate the entire display device, there is a problem in that the size of the mass needs to be increased in order to increase the vibration force, and it is difficult to modulate the frequency to control the degree of vibration.

In order to improve such a problem, shape memory alloy (SMA) and piezoelectric ceramics (Electro-Active Ceramics; EAC) have been developed as actuator materials. The actuator using the shape memory alloy (SMA) is driven on the principle of using heat generated by flowing a current through the shape memory alloy (SMA), and can generate a very large force. An actuator using a piezoelectric ceramic (EAC) is driven using vibration generated when a relatively high voltage is applied to the piezoelectric ceramic, and has the advantage of being able to control it at a high speed. However, it is difficult to apply the shape memory alloy (SMA) to the entire surface of the display panel because it has a slow reaction rate, short lifespan, and opaqueness, and the piezoelectric ceramic is fragile and opaque.

Accordingly, recently, an actuator technology using an electro-active polymer (EAP) has attracted many people's attention. An electro-active polymer (EAP) is a polymer that can be deformed by electrical stimulation, and refers to a polymer that can be repeatedly expanded, contracted, and bent by electrical stimulation. Among various types of electroactive polymers, ferroelectric polymers and dielectric elastomers are mainly used. For example, the ferroelectric polymer includes PVDF (Poly VinyliDene Fluoride) or P (VDF-TrFE) (Poly (VinyliDene Fluoride)-TriFlurorEtylene), and the dielectric elastomer includes a silicone-based polymer, a urethane-based polymer, or an acrylic polymer.

The ferroelectric polymer has advantages of being easy to handle due to its excellent flexibility and having an excellent dielectric constant, but it is difficult to be used on the entire surface of a display device because it has very poor optical characteristics including light transmittance. In addition, although the dielectric elastomer has excellent transmittance, it has a relatively low dielectric constant compared to the ferroelectric polymer, so it is difficult to use it as it is in a display device having a relatively low driving voltage, such as a mobile display, due to a high driving voltage.

[Related technical literature]

1. Electroactive actuator (Patent Application No. 10-2010-0059089)

2. Piezoelectric actuator module and touch screen device using the same (Patent Application No. 10-2009-0128115)

As described above, the inventors of the present invention have understood that the conventional electroactive polymer (EAP) has a high driving voltage, which makes it difficult to use in a display device such as a mobile display, and has a low light transmittance, making it difficult to use on the front surface of the display device. did. Accordingly, the inventors of the present invention have invented an actuator having excellent light transmittance and high dielectric constant, and thus having a low driving voltage, and a display device including the same.

Accordingly, an object of the present invention is to provide an actuator having excellent light transmittance and haze characteristics, and thereby to provide an actuator that can be disposed on the front surface of a display panel.

Another problem to be solved by the present invention is to provide an actuator having a low driving voltage by using an electroactive layer including a dielectric elastomer and having an increased dielectric constant.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An actuator according to an embodiment of the present invention includes an electroactive layer including a dielectric elastomer and a ferroelectric filler, and first and second transparent electrodes attached to both surfaces of the electroactive layer. The actuator according to an embodiment of the present invention has excellent light transmittance and a low driving voltage, so that it is easy to be mounted on the front surface of the display panel.

According to another feature of the present invention, the dielectric elastomer is characterized in that at least one selected from the group consisting of an acrylic polymer, a urethane polymer, and a silicone polymer.

According to another feature of the present invention, the ferroelectric filler is characterized in that it is a piezoelectric ceramic, carbon nanoparticles, metal nanoparticles or conductive polymer.

According to another feature of the present invention, the piezoelectric ceramic is characterized in that the particle diameter is 300 nm or less.

According to another feature of the present invention, the weight ratio of the dielectric elastomer and the ferroelectric filler is 99:1 to 85:15.

According to another feature of the present invention, the electroactive layer is characterized in that the dielectric constant is 5 or more.

According to another feature of the present invention, the electroactive layer is characterized in that the transmittance is 85%.

A display device according to another embodiment of the present invention includes a display panel; actuator; and a touch panel, wherein the actuator comprises an electroactive layer including a dielectric elastomer and a ferroelectric filler.

The details of other embodiments are included in the detailed description and drawings.

According to the present invention, by improving the light transmittance of the electroactive layer, an actuator that can be disposed on the entire surface of the display panel can be manufactured, and finally, direct tactile feedback can be delivered to the user.

In addition, in the present invention, the dielectric constant is improved, so that it is possible to manufacture an actuator capable of transmitting a vibrotactile sensation at a low voltage compared to an actuator including a conventional dielectric elastomer.

The effect according to the present invention is not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is a schematic cross-sectional view for explaining the structure of an actuator according to an embodiment of the present invention.
2 is a schematic cross-sectional view for explaining the structure of an actuator according to another embodiment of the present invention.
3 is a schematic exploded perspective view illustrating a structure of a display device including an actuator according to an exemplary embodiment.
4 is a diagram illustrating examples in which a display device according to various embodiments of the present disclosure may be advantageously utilized.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and thus the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless otherwise explicitly stated.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between the two parts unless 'directly' is used.

Reference to a device or layer “on” another device or layer includes any intervening layer or other device directly on or in the middle of another device.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

Like reference numerals refer to like elements throughout.

The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component.

Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship. may be

In the present invention, the permittivity (ε, permittivity) means the ratio of the strength of the applied electric field to the strength of the internal electric field strengthened by the displacement of the electric charge inside when the electric field acts on the dielectric. The permittivity ε is expressed as in Equation 1 below.

[Equation 1]

ε=ε ₀ ε _r

(ε ₀ : vacuum permittivity, ε _r : relative permittivity)

In the present invention, the front surface of the display panel refers to a surface in a direction in which an image is displayed from the display panel, refers to a surface where a user faces the display panel of the display device, and the rear surface of the display panel is a surface on which an image is displayed from the display panel. the opposite side of the direction.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view for explaining the structure of an actuator according to an embodiment of the present invention. Referring to FIG. 1 , an actuator 100 according to an embodiment of the present invention includes an electroactive layer 110 including a dielectric elastomer and a ferroelectric filler, and a first transparent electrode 121 attached to both surfaces of the electroactive layer 110 . ) and a second transparent electrode 122 .

The actuator 100 is deformed according to an electric field generated by a voltage applied to each of the first transparent electrode 121 and the second transparent electrode 122 . Specifically, the direction and shape in which the actuator 100 is deformed may be different depending on the potential of the voltage applied to the first transparent electrode 121 and the second transparent electrode 122 , and the electric field depends on the amount of the applied voltage. The magnitude of the deformation and vibration may be different by changing the intensity of the .

Referring to FIG. 1 , the electroactive layer 110 is disposed between the first transparent electrode 121 and the second transparent electrode 122 .

The electroactive layer 110 is deformed by electrical stimulation to implement vibration or warpage. Specifically, in the electroactive layer 110 , polarization occurs inside the electroactive layer 110 by an electric field applied between the first transparent electrode 121 and the second transparent electrode 122 . A Maxwell stress is applied to the electroactive layer 110 by an electrostatic attraction (Coulombic force) generated by such a polarization phenomenon. The magnitude of Maxwell's stress is expressed by Equation 2 below.

[Equation 2]

(ε ₀ : vacuum permittivity, ε _r : relative permittivity, E: electric field, V: voltage, t: electroactive layer thickness)

Here, the Maxwellian stress refers to the force of the electroactive polymer to contract in the thickness direction and expand in the longitudinal direction. As a result, the electroactive layer 110 is bent or vibrated according to the strength and direction of the applied electric field.

The electroactive layer 110 includes a dielectric elastomer and a ferroelectric filler.

First, a dielectric elastomer is a polymer material in which electrostrictive strain is induced by an electric field. .

The dielectric elastomer may be one commonly used in the art to which the present invention pertains, and is not limited thereto, but may be at least one selected from the group consisting of an acrylic polymer, a urethane polymer, and a silicone polymer. As an example of the dielectric elastomer, it may be a compound in which an acrylic polymer and a silicone polymer are blended.

In particular, the dielectric elastomer of the present invention is preferably a silicone-based polymer having the advantages of low viscoelasticity and a wide temperature range, and more preferably polydimethyl siloxane (PDMS).

The dielectric elastomer is preferably a compound having a large polarity, that is, a large permittivity, in order to obtain a large deformation with a small driving voltage. For example, it is more preferable that the dielectric constant measured at 1 kHz is 2.5.

The dielectric elastomer may have a weight average molecular weight of 10,000 g/mol or more in consideration of mechanical properties required for the actuator.

Next, the ferroelectric filler of the present invention is a material for improving the dielectric constant of the electroactive layer 110 by mixing with the dielectric elastomer, but is not limited thereto, but a group consisting of piezoelectric ceramics, carbon nanoparticles, metal nanoparticles, and conductive polymers. It is preferable to include at least one selected from

The piezoelectric ceramic is not limited thereto, but preferably includes a piezoelectric metal oxide including metal atoms such as lead (Pb), zirconium (Zr), titanium (Ti), and barium (Ba). For example, the piezoelectric ceramic may be a perovskite-type oxide made of lead zirconate titanate (PbZrO3-PbTiO3, PZT) or barium titanate (BaTiO3).

The piezoelectric ceramic preferably has a particle diameter of 300 nm or less, more preferably 200 nm or less. When the particle diameter satisfies the above range, the dielectric constant of the electroactive layer 110 is increased and the piezoelectric ceramic particles can be uniformly dispersed in the dielectric elastomer, so that the transmittance of the electroactive layer 110 is improved. However, when the particle diameter of the piezoelectric ceramic exceeds 300 nm, the transparency of the electroactive layer 110 may be greatly reduced with only a small amount of addition.

The particle diameter in the present invention can be measured by the measuring method employed in the present invention, but is not limited thereto, but is not limited thereto, but is not limited thereto, but is not limited thereto, but is not limited thereto, but is not limited thereto, such as transmission electron microscopy (TEM), scanning probe microscopy (SPM), small-angle X-ray scattering method or X-ray diffraction method. (XRD).

On the other hand, as the ferroelectric filler of the present invention, barium titanate is most preferable in terms of securing transparency of the electroactive layer 110 and remarkably improving the dielectric constant of the electroactive layer 110 .

At this time, the degree of crystallinity of barium titanate is preferably 70% or more, and more preferably 80% or more. When the crystallinity of barium titanate is 70% or more, the dielectric constant and volume resistivity of barium titanate are large because of high crystallinity. In this case, the crystallinity may be measured by an X-ray diffraction (XRD) apparatus.

On the other hand, the barium titanate used in the present invention may be prepared to have a particle diameter and crystallinity, and may be prepared by using a solid-phase reaction method, a hydrothermal synthesis method, a sol-gel method, and the like.

For example, according to the hydrothermal synthesis method, barium titanate can be produced by supplying a metal complex containing barium (Ba) and titanium (Ti) in a supercritical water environment and staying there for a predetermined time. At this time, as the metal complex, an alkoxide or hydroxide of a single metal containing barium or titanium may be used in combination to form a composition of a perovskite compound, and a complex alkoxide containing both barium and titanium may be used. can also be used. According to the above method, it is possible to easily produce barium titanate particles having a crystallinity of 70% or more and a particle diameter of 300 nm or less.

Carbon nanoparticles include, but are not limited to, single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, graphite, carbon black ( At least one selected from the group consisting of carbon black), carbon fibermers and fullerenes is preferable. In particular, single-walled carbon nanotubes are more preferable in that the dielectric constant of the electroactive layer 110 is greatly improved in a low frequency region.

The metal nanoparticles are not limited thereto, but may be nanowires, nanorods, nanopores, or nanotubes including gold (Au) or silver (Ag).

Conductive polymers include, but are not limited to, polyfluorene, polyphenylene, polypyrene, polyazulene, polynaphthalene, polyacetylene (PAC), poly -p-phenylene vinylene (poly(p-phenylene vinylene, PPV), polypyrrole (PPY), polycarbazole (polycarbazole), polyindole (polyindole), polyzepine (polyzepine), polythienylenevinylene ( poly(thienylene vinylene), Poly Thienylene Vinylenepolyaniline (PANI), poly(thiophene), poly(p-phenylene sulfide, PPS), poly(3,4- Poly(3,4-ethylenedioxy thiophene, PEDOT), poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate, PSS) (PEDOT:PSS), poly(3 ,4-Ethylenedioxythiophene)-tetramethacrylate (PEDOT-TMA) and at least one selected from the group consisting of polyfuran is preferable.

The conductive polymer preferably has an electrical conductivity of 10 ^-6 S/cm or ^{more, more preferably 10 -2} S/cm or more. When the electrical conductivity of the conductive polymer satisfies the above range, the dielectric constant of the electroactive layer 110 may be improved by the action with the dielectric elastomer.

In the electroactive layer 110 according to the present invention, the weight ratio of the dielectric elastomer and the ferroelectric filler is preferably 99.9:0.1 to 85:15, and more preferably 99:1 to 90:10. When the content of the ferroelectric filler is less than the above range, it is difficult to expect an effect of improving the dielectric constant of the electroactive layer 110 . In addition, when the content of the ferroelectric filler exceeds the above range, the effect of increasing the permittivity is insignificant, and a phenomenon in which the ferroelectric filler is lowered occurs. In addition, the transmittance of the electroactive layer 110 is greatly reduced, so that the actuator 100 cannot be disposed on the entire surface of the display panel.

On the other hand, in the electroactive layer 110 of the present invention, the dielectric constant measured at 1 kHz is preferably 5.0 or more, more preferably 7.0 or more. Polydimethyl siloxane (PDMS), which is most widely used as a dielectric elastomer, generally has a dielectric constant of about 2.5 to 3.0, but when a ferroelectric filler as in the present invention is used, the dielectric constant is improved to 7.0 or more, more preferably It can be improved to 9.0 or higher.

In addition, the electroactive layer 110 of the present invention preferably has a light transmittance of 85%, more preferably 90% or more, based on a thickness of 100 μm. In general, in order to arrange the actuator on the front surface of the display panel, the light transmittance of the actuator should be 80% or more. In particular, in the case of a ferro-electric polymer such as PVDF (Poly VinyliDene Fluoride) polymer or P (VDF-TrFE) (Poly (VinyliDene Fluoride)-TriFlurorEtylene) polymer that can be used as an electroactive layer, generally, 80% Since it has the following light transmittance, there is a problem in that it is difficult to arrange it on the entire surface of the display panel. However, the present invention can provide the actuator 100 having excellent light transmittance and dielectric constant by including the dielectric elastomer and the ferroelectric filler.

The electroactive layer 110 of the present invention preferably has a thickness of 50 μm to 1000 μm, more preferably 100 μm to 500 μm.

A first transparent electrode 121 and a second transparent electrode 122 for supplying power are attached to both surfaces of the electroactive layer 110 .

In FIG. 1 , the electrode disposed on the lower surface of the electroactive layer 110 is shown as the first transparent electrode 121 , and the electrode disposed on the upper surface of the electroactive layer 110 is shown as the second transparent electrode 122 .

A voltage is applied from the outside to the first transparent electrode 121 and the second transparent electrode 122 to form an electric field. Here, electrical properties of the voltage applied to the first transparent electrode 121 and the second transparent electrode 122 are opposite to each other. That is, when a positive (+) voltage is applied to the first transparent electrode 121 , a negative (-) voltage is applied to the second transparent electrode 122 , and a negative (-) voltage is applied to the first transparent electrode 121 . When a voltage of , a positive (+) voltage is applied to the second transparent electrode 122 . Here, as the electrical properties of the voltage applied to the first transparent electrode 121 and the electrical properties of the voltage applied to the second transparent electrode 122 change oppositely to each other, the direction of the electric field is also changed. That is, the voltage applied between the first transparent electrode 121 and the second transparent electrode 122 may be an alternating current voltage, and between the first transparent electrode 121 and the second transparent electrode 122 . An electric field may be formed by the alternating voltage.

Accordingly, the electric field formed between the first transparent electrode 121 and the second transparent electrode 122 prevents polarization in the electroactive layer 110 between the first transparent electrode 121 and the second transparent electrode 122 . and the electroactive layer 110 subjected to Maxwellian stress by electrostatic attraction due to the polarization phenomenon is deformed and vibrated.

In this case, the first transparent electrode 121 and the second transparent electrode 122 may be made of the same material. Specifically, the first transparent electrode 121 and the second transparent electrode 122 include a transparent conductive material. Although not limited thereto, indium tin oxide (ITO), carbon nanotubes (CNT), graphene, metal nanowires, conductive polymers (PEDOT:PSS) and transparent conductive oxides ( TCO) may include one or more selected from the group consisting of.

Meanwhile, the first transparent electrode 121 and the second transparent electrode 122 may further include a binder to improve dispersibility of the transparent conductive material. The binder is not limited thereto, but polyester-based elastomers, acrylic-based elastomers, silicone-based elastomers, butadiene-based elastomers, isoprene-based elastomers, styrene-based elastomers, siloxane-based elastomers, silsesquioxane-based elastomers, singles and copolymers thereof It is preferable to include at least one selected from the group consisting of styrene-ethylene-butylene-styrene block copolymer (SEBS), polydimethyl siloxane (PDMS) or polyethylenedioxythiophene (PEDOT). more preferably. In this case, the binder preferably contains 20 parts by weight to 99 parts by weight, and more preferably 40 parts by weight to 80 parts by weight, based on 100 parts by weight of the transparent conductive material.

The first transparent electrode 121 and the second transparent electrode 122 may be formed by a method commonly used in the technical field of the present invention, but is not limited thereto, for example, the upper surface of the electroactive layer 110 . And it is possible to form a transparent electrode using a sputtering method or a slot coating method on the lower surface.

The actuator 100 of the present invention includes an electroactive layer 110 having excellent dielectric constant and light transmittance. That is, since the dielectric constant of the electroactive layer 110 is significantly higher than that of the electroactive layer including the conventional dielectric elastomer, the driving voltage of the actuator 100 can be lowered. In addition, since the actuator 100 of the present invention has superior light transmittance compared to the conventional electroactive layer including a ferroelectric polymer, it can be positioned on the display panel, so that the user can provide direct tactile feedback from the front of the display device. can

2 is a schematic cross-sectional view for explaining an actuator 200 according to another embodiment of the present invention. Referring to FIG. 2, the actuator 200 according to the second embodiment of the present invention includes a multi-layered electroactive layer, and more specifically, the multi-layered electroactive layer is a first electroactive layer 211, a second electroactive layer ( 212) and the third electroactive layer 213, which is shown as three layers above and below.

At this time, the transparent electrodes having opposite voltages are alternately disposed between the respective electroactive layers, and are alternately disposed from the lowermost surface of the first electroactive layer 211 .

More specifically, the actuator 200 according to the second embodiment includes the first transparent electrode 221 on the lower surface of the first electroactive layer 211 and the second transparent electrode 222 on the upper surface of the first electroactive layer 211 . is disposed, a second electroactive layer 212 is disposed on the second transparent electrode 222 , a third transparent electrode 223 is disposed on an upper surface of the second electroactive layer 212 , and a third transparent electrode 223 is disposed. ) is disposed on the third electroactive layer 213 , and a fourth transparent electrode 224 is disposed on the upper surface of the third electroactive layer 213 .

The actuator 200 according to the second embodiment is generated by voltages applied to the first transparent electrode 221 , the second transparent electrode 222 , the third transparent electrode 223 , and the fourth transparent electrode 224 , respectively. deformed according to the electric field.

In this case, the voltages applied to the first transparent electrode 221 , the second transparent electrode 222 , the third transparent electrode 223 , and the fourth transparent electrode 224 are alternately applied to each transparent electrode. That is, voltages having the same electrical properties are applied to the first transparent electrode 221 and the third transparent electrode 223 , and the second transparent electrode 222 and the fourth transparent electrode 224 are connected to the first transparent electrode ( A voltage having an electrical property opposite to that of the voltage applied to the 221 and the third transparent electrode 223 is applied. For example, when a negative (-) voltage is supplied to the first transparent electrode 221 and the third transparent electrode 223 , a positive (+) voltage is applied to the second transparent electrode 222 and the fourth transparent electrode 224 . ) can be supplied.

As described in FIG. 1 , the electrical properties of the voltage applied to the first transparent electrode 221 and the third transparent electrode 223 and the voltage applied to the second transparent electrode 222 and the fourth transparent electrode 224 . As the electrical properties of , change opposite to each other, the direction of the electric field also changes.

On the other hand, in the case of the actuator 200 including a multi-layered electroactive layer as shown in FIG. 2 , a voltage is uniformly applied to each transparent electrode, and in order to easily manufacture the actuator, each transparent electrode is applied with the same voltage. The transparent electrodes may have a structure in which side portions are connected to each other. In this case, the side to be connected is preferably connected with the same material as the transparent electrode.

For example, one side of the first transparent electrode 221 and the third transparent electrode 223 to which the same voltage is applied is connected to the left side of the first electroactive layer 211 and the second transparent electrode 222 . The opposite side of the second transparent electrode 222 and the fourth transparent electrode 224 to which the same voltage is applied is connected to wrap around the right side of the second electroactive layer 211 and the third transparent electrode 223 . can

The actuator 200 according to the second embodiment is characterized in that it includes a multi-layered electroactive layer 210, and in this case, it can be easily driven even at a low voltage.

However, when it includes a multi-layered electroactive layer and a transparent electrode like the actuator 200 according to the second embodiment, it is preferably formed as thin as possible in order not to affect the deformation of the actuator 200, and the first Compared to the actuator 100 according to the embodiment, the electroactive layer and the transparent electrode may be formed to have a thin thickness. Although not limited thereto, for example, each of the first electroactive layer 211 , the second electroactive layer 212 , and the third electroactive layer 213 may have a thickness of 200 μm or less, and the first transparent electrode 221 . , the second transparent electrode 222 , the third transparent electrode 223 , and the fourth transparent electrode 224 may each have a thickness of 50 nm or less.

At this time, the specific configuration of each of the first electroactive layer 211 , the second electroactive layer 212 and the third electroactive layer 213 shown in FIG. 2 is the same as the electroactive layer 110 described in FIG. 1 , and the first The detailed configuration of each of the transparent electrode 221 , the second transparent electrode 222 , the third transparent electrode 223 , and the fourth transparent electrode 224 is also the first transparent electrode 121 and the second transparent electrode described in FIG. 1 . Since it is the same as (121), a detailed description thereof will be omitted.

3 is a schematic exploded perspective view for explaining the structure of the display device 300 including the actuator 100 according to an embodiment of the present invention.

Referring to FIG. 3 , a display device 300 according to an exemplary embodiment includes a display panel 310 , an actuator 100 , and a touch panel 320 . More specifically, the display panel 310 is disposed between the lower cover 330 and the upper cover 340 , the actuator 100 is disposed on the display panel 310 , and the touch panel ( 320) is placed.

The lower cover 330 is disposed under the display panel 310 to cover the lower portions of the touch panel 320 , the display panel 310 , and the actuator 100 . The lower cover 330 protects internal components of the display device 300 from external impact and penetration of foreign substances or moisture. For example, the lower cover 330 may be made of a material such as glass having good hardness or plastic having good processability and can be thermoformed, but is not limited thereto. In addition, the lower cover 330 may be made of a material that can be deformed together according to the change in ductility and shape of the actuator 100 . For example, the lower cover 330 may be made of a material such as plastic having flexibility, but is not limited thereto.

The display panel 310 is disposed on the lower cover 330 and is disposed under the actuator 100 , and may be, for example, a liquid crystal display (LCD) or an organic light emitting display (OLED).

The liquid crystal display includes a lower substrate, an upper substrate, a pixel electrode, a common electrode, a color filter, a polarizing film, and a liquid crystal layer interposed between the upper substrate and the lower substrate. The liquid crystal display controls the liquid crystal by an electric field formed between a pixel electrode located in the pixel region of the liquid crystal display and a common electrode formed on a lower substrate or an upper substrate, and transmits through a polarizing film according to the degree of control of the liquid crystal. Light incident from a separate light source is selectively transmitted. The selectively transmitted light passes through the color filter located on the upper substrate, and an image is displayed. In the liquid crystal display device, a separate light source may be formed on a side surface of the liquid crystal display device instead of the rear surface to be driven as the display device.

The display panel 310 of the display device 300 according to an exemplary embodiment may be an organic light emitting diode display (OLED). The organic light emitting display device is a display device in which the organic light emitting layer emits light by flowing a current through the organic light emitting layer. The organic light emitting diode display uses an organic light emitting layer to emit light of a specific wavelength. The organic light emitting diode display includes at least a cathode, an organic light emitting layer, and an anode. The display panel 310 may be driven in a passive matrix and an active matrix.

The organic light emitting diode display may be configured in a top emission method and a bottom emission method. The top emission type organic light emitting display device refers to an organic light emitting display device in which light emitted from the organic light emitting diode is emitted to an upper portion of the organic light emitting diode display. It refers to an organic light emitting diode display that is emitted toward the top surface of a substrate on which a thin film transistor is formed. The bottom emission type organic light emitting display device refers to an organic light emitting display device in which light emitted from the organic light emitting diode is emitted to the lower portion of the organic light emitting diode display. It refers to an organic light emitting diode display that is emitted toward a lower surface of a substrate on which a thin film transistor is formed. Furthermore, the organic light emitting diode display may be configured in a double-sided light emitting method. The double-sided light emitting display device refers to an organic light emitting diode display in which light emitted from the organic light emitting diode is emitted to the upper and lower portions of the organic light emitting diode display, and is an organic light emitting diode display capable of being simultaneously driven by a top emission method and a bottom emission method. means a light emitting display device.

The organic light emitting display device may include a flexible substrate and may be a flexible organic light emitting display device having flexibility. The flexible organic light emitting diode display may be deformed in various directions and angles by external force.

The actuator 100 is disposed on the display panel 310 and below the touch panel 320 . In this case, the actuator 100 may be disposed to be in direct contact with the display panel 310 , and an adhesive layer may be further disposed between the upper surface of the display panel 310 and the lower surface of the actuator 100 . The display panel 310 and the actuator 100 may be adhered to each other by the adhesive layer. The adhesive is not limited thereto, but it is preferable to use an optically clear adhesive such as an optical clear adhesive (OCA) or an optical clear resin (OCR).

Meanwhile, since specific components of the actuator 100 are the same as those described with reference to FIGS. 1 and 2 , a detailed description thereof will be omitted.

The touch panel 320 is disposed on the actuator 100 , and performs a function of detecting an external touch generated by a user pressing a surface while viewing an image displayed on the display panel 310 , and providing touch coordinates. do.

The touch panel 320 may be classified according to the arrangement position. For example, an add-on method for attaching to the outer surface of the display panel 310 , an on-cell method for depositing the touch panel 320 on the display panel 310 , and display There is an in-cell method formed inside the panel 310 , and the like.

In addition, the touch panel 320 may be classified into a pressure reduction method or a capacitive method according to a driving method, and the capacitive method may be further divided into a SelfCap method and a mutual method.

The touch panel 320 may include two electrodes crossing each other. For example, the touch panel 320 may include horizontally patterned electrodes and vertically patterned electrodes, and the patterned electrodes may be disposed to cross each other.

Also, the touch panel 320 may be electrically connected to the actuator 100 . Specifically, the touch panel 320 may be electrically connected to the first transparent electrode 121 and the second transparent electrode 122 of the actuator 100 . Accordingly, signals or voltages by various touch inputs input from the touch panel 320 may be transmitted to the actuator 100 .

Since the touch panel 320 of the present invention is disposed on the display panel 310, it is desirable to have transparency and flexibility. The touch panel 320 is not limited thereto, but may be formed of a transparent conductive material such as Indium-Tin-Oxide (ITO) to prevent deterioration in visibility of the display device 300 .

The upper cover 340 is disposed on the touch panel 320 to cover the display panel 310 , the actuator 100 , and upper portions of the touch panel 320 . The upper cover 340 may have the same function as the lower cover 330 . Also, the upper cover 340 may be made of the same material as the lower cover 330 .

The display device 300 including the actuator 100 according to an embodiment of the present invention uses the electroactive layer 110 having excellent light transmittance and dielectric constant, so that the driving voltage is low and light transmittance is excellent. can be placed. Accordingly, the display device 300 of the present invention can deliver a direct touch feeling and feedback to the user.

4 is a diagram illustrating examples in which a display device according to various embodiments of the present disclosure may be advantageously utilized.

4A is an exemplary external view of a mobile display device 400 including an actuator according to an embodiment of the present invention. In this case, the mobile display device 400 may be a miniaturized device such as a smart phone, a mobile phone, a tablet PC, or a PDA. When the actuator of the present invention is installed in the mobile display device 400 , unlike the prior art in which the entire mobile display device 400 is vibrated by a user's touch, vibration is generated only in the touched part or by touch. Vibration can be delivered directly to the user even to the smallest difference depending on the intensity. Since the user may feel a vibration along with a touch when watching a video, playing a game, or inputting a button with the mobile display device 400 , more synesthetic information may be transmitted from the mobile display device 400 .

4B is an exemplary external view of a vehicle navigation system 500 including an actuator according to an embodiment of the present invention. The vehicle navigation 500 may include a display device and a plurality of operation elements, and may be controlled by a processor installed inside the vehicle. When the display device of the present invention is applied to the vehicle navigation system 500, it is possible to provide various tactile information to the user, such as the height of the road, the state of the road, and the progress of the vehicle.

4C is an exemplary external view of a TV 600 including an actuator according to an embodiment of the present invention. When the display device of the present invention is used in a display device such as a TV 600 or a monitor, the user can feel the texture of a specific object, the speaker's state, etc. through the display device as if they were actually experiencing it, so that a more realistic image can be viewed. you can enjoy

FIG. 4D is an exemplary external view of an outdoor billboard 700 including an actuator according to an embodiment of the present invention. When the display device of the present invention is applied to the outdoor billboard 700, tactile information about an advertisement item to be sold can be directly transmitted to the user, thereby maximizing the advertisement effect.

4E is an exemplary external view of a slot machine 800 including an actuator according to an embodiment of the present invention. The slot machine 800 may include a housing in which a display device and various processors are incorporated. When the display device of the present invention is applied to the slot machine 800, by directly operating the image, it is possible to realistically provide lever pulling, rotation of the roulette wheel, movement of the roulette ball, etc. can be doubled.

4 (f) is an exemplary external view of the electronic blackboard 900 including an actuator according to an embodiment of the present invention. The electronic blackboard 900 may include a display device, a speaker, and a structure for protecting them from external impact. When the display device of the present invention is applied to the electronic blackboard 900 , the educator can be provided with a feeling of writing directly on the blackboard 900 when inputting lecture contents into the display device with a stylus pen or a finger. In addition, when the trainee applies a touch input to the image displayed on the electronic blackboard 900 , tactile feedback suitable for the image can be provided to the trainee, so that the effect of education can be maximized.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for illustration of the present invention, and the scope of the present invention is not limited by the following examples.

Example - actuator manufacturing

Example 1

A mixture was prepared by mixing polydimethyl siloxane (PDMS) as a dielectric elastomer and barium titanate (particle diameter: 120 nm) as a ferroelectric filler in hexane as a solvent. At this time, the weight ratio of polydimethyl siloxane (PDMS) and barium titanate was 95:5. The mixture was applied on a substrate and dried to obtain an electroactive layer having a thickness of 100 μm. Then, indium tin oxide (Induim Tin Oxide, ITO) was slit-coated on both sides of the prepared electroactive layer to prepare an actuator in which a transparent electrode was formed.

Example 2

An actuator was manufactured in the same manner as in Example 1, except that the weight ratio of polydimethyl siloxane (PDMS) and barium titanate was 90:10.

Comparative Example 1

An actuator was manufactured in the same manner as in Example 1, except that an electroactive layer containing only polydimethyl siloxane (PDMS) as a dielectric elastomer was formed.

Comparative Example 2

An actuator was manufactured in the same manner as in Example 1, except that an electroactive layer containing only P(VDF-TrFE) (Poly(VinyliDene Fluoride)-TriFlurorEtylene) polymer, which is a ferroelectric polymer rather than a dielectric elastomer, was formed.

Comparative Example 3

An actuator was manufactured in the same manner as in Example 1, except that the weight ratio of polydimethyl siloxane (PDMS) to barium titanate was 80:20.

Comparative Example 4

An actuator was manufactured in the same manner as in Example 1, except that the weight ratio of polydimethyl siloxane (PDMS) to barium titanate was 70:30.

Comparative Example 5

An actuator was manufactured in the same manner as in Example 1, except that the weight ratio of polydimethyl siloxane (PDMS) and barium titanate was 40:60.

Reference Example 1

An actuator was manufactured in the same manner as in Example 1, except that barium titanate having a particle diameter of 300 nm was used.

Reference Example 2

An actuator was manufactured in the same manner as in Example 2, except that barium titanate having a particle diameter of 300 nm was used.

Experimental example 1 - dielectric constant measurement

The dielectric constants of the actuators manufactured according to Examples 1 to 2 and Comparative Examples 1 to 5 were measured by measuring the capacitance at a frequency of 1 kHz using an LCR meter 4284A, and calculating using Equation 3 below. The measurement results are shown in Table 1 below.

[Equation 3]

ε = C × t / ε _o × A

(ε: dielectric constant, C: capacitance, ε _o: vacuum dielectric constant, t: thickness of the electroactive layer, A: contact cross-sectional area of the electrode)

Experimental example 2 - Measurement of optical properties

The light transmittance and haze of the actuators prepared according to Examples 1 to 2 and Comparative Examples 1 to 7 were measured using a haze meter (JCH-300S, Oceanoptics). The measurement results are indicated in Table 1 below.

division permittivity
(at 1kHz) light transmittance
(%) haze
(%) Example 1 7.8 89.5 3.5 Example 2 8.5 87.3 4.3 Comparative Example 1 2.7 89.8 4.9 Comparative Example 2 12 75 15 Comparative Example 3 8.5 to 9.0 40.2 37.8 Comparative Example 4 8.5 to 9.0 27.5 50 or more Comparative Example 5 8.5 to 9.0 15.5 50 or more Reference Example 1 7.9 60.6 50 or more Reference Example 2 8.2 22.9 50 or more

As confirmed through Table 1, in Examples 1 to 2, compared to Comparative Example 1 not including the ferroelectric filler, it could be confirmed that the dielectric constant was significantly increased, and in Comparative Example 2 including the ferroelectric polymer In comparison, it was confirmed that the light transmittance was excellent.

On the other hand, as can be seen from Comparative Examples 3 to 5, when the content of the ferroelectric filler is outside the range of the present invention, it was confirmed that not only the dielectric constant no longer increased, but also the light transmittance was significantly reduced.

On the other hand, as can be seen through Reference Examples 1 and 2, when the particle diameter of the ferroelectric filler, particularly the piezoelectric ceramic, exceeds 300 nm, it was confirmed that the light transmittance of the actuator was significantly reduced.

As can be seen from the above Examples and Comparative Examples, it was found that the dielectric constant and light transmittance of the actuator including the electroactive layer of the present invention were improved at the same time. Accordingly, the actuator of the present invention has a low driving voltage and may be disposed on the front surface of the display panel, thereby providing direct and various tactile feedback to the user.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made within the scope without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100, 200: actuator
110, 210: electroactive layer
111: first electroactive layer
112: second electroactive layer
113: third electroactive layer
121, 221: first transparent electrode
122. 222: second transparent electrode
223: third transparent electrode
224: fourth transparent electrode
300: display device
310, 410, 510, 610, 710, 810, 910: display panel
320: touch panel
330: lower cover
340: top cover
400: mobile display device
500: car navigation
600: TV
700: outdoor billboard
800: slot machine
900: electronic blackboard

Claims (14)

an electroactive layer comprising a dielectric elastomer and a ferroelectric filler; and
A first transparent electrode and a second transparent electrode disposed on both sides of the electroactive layer,
The weight ratio of the dielectric elastomer to the ferroelectric filler is 99:1 to 90:10,
The dielectric elastomer is polydimethyl siloxane (PDMS), and the ferroelectric filler is a piezoelectric ceramic having a particle diameter of 200 nm or less. delete delete delete According to claim 1,
The piezoelectric ceramic is at least one selected from the group consisting of lead (Pb), zirconium (Zr), titanium (Ti) and barium (Ba), the actuator. 6. The method of claim 5,
The piezoelectric ceramic is at _{least one selected from the group consisting of barium titanate (BaTiO 3} ) and lead zirconate titanate (PZT), the actuator. delete delete delete delete delete According to claim 1,
The electroactive layer has a dielectric constant of 5.0 or more measured at 1 kHz, the actuator. According to claim 1,
a second electroactive layer and a third electroactive layer disposed on the electroactive layer;
a third transparent electrode disposed between the second electroactive layer and the third electroactive layer; and
and a fourth transparent electrode disposed on the third electroactive layer. A display device having a display panel, a touch panel and an actuator, comprising:
The actuator is
an electroactive layer comprising a dielectric elastomer and a ferroelectric filler; and
A first transparent electrode and a second transparent electrode disposed on both sides of the electroactive layer,
The weight ratio of the dielectric elastomer to the ferroelectric filler is 99:1 to 90:10,
The dielectric elastomer is polydimethyl siloxane (PDMS), and the ferroelectric filler is a piezoelectric ceramic having a particle diameter of 200 nm or less.

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