KR20170080272A - Touch sensitive device, display device comprising the same and method of manufacturing the same - Google Patents

Abstract

A contact-sensitive device, a display device including the same, and a manufacturing method thereof are provided. The contact sensitive device includes an electroactive layer made of a dielectric elastomer in which a nanowire is dispersed and an electrode disposed on at least one side of the electroactive layer. The present invention can improve the driving displacement and the vibration intensity of the contact-sensitive element by improving the dielectric constant of the electro-active layer using nanowires, and can provide a contact-sensitive element having excellent light transmittance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a touch sensing device, a display device including the same,

The present invention relates to a touch sensitive device, a display device including the touch sensitive device, and a manufacturing method thereof, and more particularly, to a touch sensitive device including an electroactive layer having improved light transmittance and relative dielectric constant, a display device including the same, .

2. Description of the Related Art [0002] In recent years, in response to a demand of users to easily use various display devices including a liquid crystal display device and an organic light emitting display device, use of a touch-type display device for touching and inputting a display device has become commonplace. Accordingly, studies using a haptic device have been continuing to provide direct and diverse touch feedback to the user. In particular, since the conventional haptic device is attached to the back surface of the display panel, it is difficult to provide immediate and minute feedback on the user's touch. Therefore, researches are actively conducted to place the haptic device on the upper part of the display panel, thereby providing sensitive and diverse direct feedback to the user's touch.

Conventionally, a vibration motor such as an Eccentric Rotating Mass (ERM) or a Linear Resonant Actuator (LRA) has been used as a display device with such a haptic device. The vibration motor is configured to vibrate the entire display device. To increase the vibration intensity, there is a problem that the size of the mass body must be increased, frequency modulation is difficult to control the degree of vibration, and the response speed is very slow have. Further, since the eccentric motor and the linear resonance motor are made of an opaque material, it is impossible to arrange them on the display panel.

Shape Memory Alloys (SMA) and Electro-Active Ceramics (EAC) have been developed as materials for haptic devices in order to overcome the above problems. However, Shape Memory Alloy (SMA) is made of opaque material with a slow reaction rate, short life span. In addition, piezoelectric ceramics (EAC) have a problem that they are easily broken by external impact due to low durability against external impact, and are opaque and difficult to be thinned.

[Related Technical Literature]

One. Haptic Effect Generation Method and Haptic Support System Using ERM Actuator (Korean Patent Application No. 10-2013-0011958)

Accordingly, a problem to be solved is to provide a contact-sensitive device having improved relative permittivity of an electroactive layer and improved driving displacement and vibration intensity, and a display device including the same.

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

According to an aspect of the present invention, there is provided a touch sensing device including: an electroactive layer formed of a dielectric elastomer in which a nanowire is dispersed; and an electrode disposed on at least one surface of the electroactive layer, .

According to an aspect of the present invention, there is provided a display device including a display panel and a touch sensitive device on the display panel, wherein the contact sensitive device includes a dielectric layer formed of a dielectric elastomer in which nanowires are dispersed, And an electrode disposed on at least one surface of the electroactive layer.

 According to an aspect of the present invention, there is provided a method of manufacturing a touch sensing device, comprising: electrospinning a polymer solution including a ferroelectric polymer to form a nanofiber made of a ferroelectric polymer; Forming a nanowire by pulverizing the nanofiber, mixing the nanowire and the dielectric elastomer to form a mixture, and coating the mixture to form an electroactive layer.

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

The present invention has the effect of improving the driving displacement and the vibration intensity of the contact sensitive element by improving the relative dielectric constant of the electroactive layer made of the ferroelectric polymer.

In addition, the present invention can provide a contact-sensitive element which is excellent in not only dielectric constant but also dispersibility, and has excellent light transmittance.

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

1A is a schematic cross-sectional view illustrating a variable device according to an embodiment of the present invention.
1B is an enlarged view of the X region of FIG.
2 is a schematic cross-sectional view illustrating a touch sensing device according to an embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a variable device according to an embodiment of the present invention.
4A is a schematic view for explaining a step of forming nanofibers in a method of manufacturing a variable element according to an embodiment of the present invention.
FIG. 4B is a schematic view for explaining a nanofiber formed by the step of forming a nanofiber in the method of manufacturing a variable element according to an embodiment of the present invention. FIG.
4C is a schematic view for explaining a step of forming nanowires by pulverizing nanofibers in a method of manufacturing a variable element according to an embodiment of the present invention.
5 is a schematic exploded perspective view illustrating a display device including a variable device according to an embodiment of the present invention.
6 is a schematic exploded perspective view illustrating a display device including a touch sensitive device according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

An element or layer is referred to as being another element or layer "on ", including both intervening layers or other elements directly on or in between.

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

Like reference numerals refer to like elements throughout the specification.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

1A is a schematic cross-sectional view for explaining a variable element according to an embodiment of the present invention. 1B is an enlarged view of the X region of FIG. 1A. 1A and 1B, a variable element 100 includes an electroactive layer 110, a first electrode 121,

The electroactive layer 110 refers to a layer that is deformed in shape as a voltage is applied and is capable of generating vibration. The electroactive layer 110 includes a dielectric elastomer 111 and a nanowire 112.

The dielectric elastomer 111 of the electroactive layer 110 is a polymeric material that causes electrostrictive strain by an electric field. The dielectric elastomer (111) is defined as a polymeric material having an electrically insulating property and structurally having an elastic restoring force.

For example, the dielectric elastomer 111 may be one or more selected from the group consisting of an acrylic polymer, a urethane polymer, and a silicone polymer, but is not limited thereto. In addition, the dielectric elastomer (111) may be a compound blended with an acrylic polymer and a silicone polymer. The dielectric elastomer 111 used in the variable element 100 according to an embodiment of the present invention may be a silicone polymer having an advantage of being operable at a low viscoelasticity and a wide temperature range and may be, for example, a polydimethylsiloxane ( polydimethyl siloxane (PDMS) can be used as the dielectric elastomer 111.

The dielectric elastomer 111 may be a compound having a high relative permittivity in order to realize a large deformation or a strong vibration with a small driving voltage. For example, the dielectric elastomer 111 may have a dielectric constant of 1.5 measured at 150 kHz. The dielectric elastomer 111 may have a weight average molecular weight of 10,000 g / mol or more so as to have elasticity required for the variable element 100.

The nanowire 112 is dispersed in the dielectric elastomer 111 as an organic filler added to the dielectric elastomer 111. [ The nanowire 112 increases the relative dielectric constant of the electroactive layer composed of the dielectric elastomer 111. [

1B, the nanowire 112 constituting the electroactive layer 110 of the variable device 100 according to an embodiment of the present invention has piezoelectricity and solubility and has a diameter of several tens to several hundreds of nm d < / RTI > and a length l of several microns.

The nanowire 112 may be made of a ferroelectric polymer. For example, the nanowire 112 may comprise, but is not limited to, a polyvinylidene fluoride (PVDF) based polymer or a polyurethane (PU) based polymer. The PVDF-based polymer means a polymer containing VDF (vinylidenefluoride) repeating units in the main chain of the polymer, and may be, for example, PVDF homo-polymer or PVDF copolymer (co-polymer). Nanowires composed of PVDF-based polymers have a high relative dielectric constant.

The nanowire 112 made of a ferroelectric polymer has a high dielectric constant. Accordingly, the nanowire 112 having a high dielectric constant can be mixed with the dielectric elastomer 111, so that the dielectric constant and the piezoelectricity of the electroactive layer 110 can be improved.

Meanwhile, the nanowire 112 constituting the electroactive layer 110 of the variable device 100 according to an embodiment of the present invention is manufactured through an electrospinning process and a crushing process. Specifically, in order to manufacture the nanowire 112 made of a ferroelectric polymer, a ferroelectric polymer dissolved in a solvent forms an nanofiber having a length of several cm or more through an electrospinning process. After the nanofibers are formed, nanowires 112 are finally formed through a grinding process. A specific process for manufacturing the nanowire 112 will be described later in detail with reference to FIG. 3 and FIGS. 4A to 4C.

Referring to FIG. 1B, the diameter d of the nanowire 112 may be 10 nm to 500 nm. When the diameter d of the nanowire 112 satisfies the above range, the particle size is sufficiently small and can be well dispersed in the solution within a range that does not deteriorate the optical characteristics such as the light transmittance of the electroactive layer 110.

Also, the length l of the nanowire 112 may be between 1 and 100 mu m. When the length l of the nanowire 112 satisfies the above range, it may have a sufficient degree of polarization and be well dispersed in a solution. When the length l of the nanowire 112 is less than 1 占 퐉, the degree of polarization of the nanowire 112 may be lowered due to the high energy generated in the course of pulverization from the nanofiber to the nanowire 112, The relative dielectric constant and piezoelectricity of the electroactive layer 110 may not be improved. When the length l of the nanowire 112 exceeds 100 mu m, the nanowire 112 is not well dispersed in the process of dispersing the nanowire 112 in the dielectric elastomer 111, 100).

In the present specification, the diameter d and length l of the nanowire 112 are measured by a transmission electron microscope (TEM), a scanning probe microscope (SPM), an incinerating X-ray scattering method, or X-ray diffraction (XRD) Can be measured.

The nanowire 112 made of a ferroelectric polymer has a? -Phase structure. In addition, the nanowire 112 has a structure in which dipoles are arranged in one direction. Generally, a ferroelectric polymer such as a PVDF-based polymer has a structure in which atoms having a large number of electrons along the main chain, for example, a fluoro group (-F) in a state of mixing a trans form and a gauche form and has an α-phase structure. Such a dipole moment in the? -Phase structure is canceled by each other, so that the degree of polarization is low. However, as described above, the nanowires 112 formed by the electrospinning process are arranged in one direction by the high voltage applied during the electrospinning process. As a result, all of the electrons having a large number of electrons are formed in a β-phase in an all-trans form, and the dipoles can be arranged uniformly. This leads to the maximum polarization. Thus, the nanowire 112 has ferroelectricity.

The nanowire 112 made of the ferroelectric polymer may have a refractive index similar to that of the dielectric elastomer 111. [ For example, when the dielectric elastomer 111 is made of PDMS having a refractive index of 1.45, the nanowire 112 may have a refractive index of 1.35 to 1.55. When the refractive index of the nanowire 112 satisfies the above range, the light transmittance of the electroactive layer 110 can be improved. Specifically, when the refractive index of the nanowire 112 is smaller than 1.35 or larger than 1.55, the refractive index of the dielectric elastomer 111 is different from that of the dielectric elastomer 111, so that the light transmittance of the electroactive layer 110 may be decreased and the reflectance may be increased. The piezoelectric ceramics or metal nanoparticles which have ferroelectricity and can be used as a filler dispersed in the dielectric elastomer 111 have a refractive index of about 2.0 or more. Therefore, when piezoelectric ceramics or metal nanoparticles are dispersed in the dielectric elastomer 111 to form an electroactive layer, the light transmittance is significantly lowered. However, the variable element 100 according to an embodiment of the present invention can be manufactured by dispersing the nanowire 112 having a refractive index similar to that of the wired elastomer to the dielectric elastomer 111 in the electroactive layer 110, Can have a high light transmittance. For example, the electric active layer 110 may have a light transmittance of 80% or more with respect to the visible light region. This shows a marked difference from the phenomenon that the light transmittance is drastically reduced when a small amount of piezoelectric ceramics or metal nanoparticles are dispersed in the electroactive layer.

In the variable element 100 according to an embodiment of the present invention, the weight ratio of the dielectric elastomer 111 and the nanowire 112 made of the ferroelectric polymer may be 99: 1 to 85:15. When the content of the nanowire 112 made of the ferroelectric polymer satisfies the above range, a sufficient improvement in the relative dielectric constant can be obtained.

Meanwhile, the electric active layer 110 of the variable device 100 according to an embodiment of the present invention may have a relative dielectric constant of 2.5 or more measured at 150 kHz. When the PDMS is used as the dielectric elastomer 111, the relative dielectric constant of PDMS measured at 150 kHz is about 2.0 or less. However, as in the variable element 100 according to the embodiment of the present invention, When the wire 112 is used as a ferroelectric filler, the relative dielectric constant of the electroactive layer 110 can be improved to 2.5 or more.

Electrodes for applying an electric field to the electroactive layer 110 are disposed on at least one surface of the electroactive layer 110 to induce vibration or warping by electrical stimulation. In the variable element 100 shown in FIGS. 1A and 1B, the first electrode 121 is disposed on the lower surface of the electroactive layer 110, the second electrode 122 is disposed on the upper surface of the electroactive layer 110 do.

The first electrode 121 and the second electrode 122 are made of a conductive material. For example, the first electrode 121 and the second electrode 122 may be formed of gold (Au), copper (Cu), titanium (Ti), chromium (Cr), molybdenum (Mo) Copper alloy or an Al-Cu alloy or a metal such as PEDOT [Poly (3,4-EthyleneDioxythiophene)]: PSS [Poly (4-Styrene Sulfonic acid)], polypyrrole, polyaniline And may be made of a conductive material. The first electrode 121 and the first electrode 121 may be formed of a conductive material such as carbon conductive grease, carbon black or carbon nanotube Carbon nanotube (CNT) and a soft electrode made by mixing an elastomer. The first electrode 121 and the second electrode 122 may be made of the same material or different materials.

The first electrode 121 and the second electrode 122 may be formed on the display panel in order to secure the transparency of the variable element 100. In this case, It is preferable to include a transparent conductive material. For example, the transparent conductive material can be selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), graphene, metal nanowires and transparent conductive oxides (TCO) It can be one kind selected.

The first electrode 121 and the second electrode 122 are disposed on both surfaces of the electroactive layer 110 in various manners. For example, the first electrode 121 and the second electrode 122 may be disposed on both surfaces of the electroactive layer 110 in a manner such as sputtering, printing, slit coating, or the like . In particular, when the first electrode 121 and the second electrode 122 are disposed of the same material, the first electrode 121 and the second electrode 122 may be disposed at the same time.

The first electrode 121 and the second electrode 122 are externally applied with a voltage to form an electric field. Here, in order to form an electric field in the electroactive layer 110, a voltage having a different magnitude may be applied to the first electrode 121 and the second electrode 122, or a voltage having an opposite electrical property may be applied to the first electrode 121 and the second electrode 122 . For example, when a positive voltage is applied to the first electrode 121, a negative voltage or a ground voltage is applied to the second electrode 122, -) is applied to the second electrode 122, a positive voltage or a ground voltage may be applied to the second electrode 122. Here, as the electrical properties of the voltage applied to the first electrode 121 and the electrical characteristics of the voltage applied to the second electrode 122 are reversed, the direction of the electric field also changes.

The AC voltage AC may be applied to the first electrode 121 and the second electrode 122, and the DC voltage DC may be applied to the first electrode 121 and the second electrode 122. When the AC voltage AC is applied to the first electrode 121 and the second electrode 122, the electroactive layer 110 can be periodically displaced to have a vibrating effect, and the first electrode 121 (DC) is applied to the second electrode 122 and the second electrode 122, the electroactive layer 110 can be kept in a bent state.

As described above, the variable device 100 according to an embodiment of the present invention includes the electroactive layer 110 including the dielectric elastomer 111 and the nanowire 112 made of the ferroelectric polymer, so that the dielectric constant and the piezoelectricity And the light transmittance is excellent.

Generally, the electro-active polymers (EAP) usable as the electroactive layer include the above-described dielectric elastomer and ferroelectric polymer. The ferroelectric polymer is advantageous in that it has excellent flexibility and is easy to handle and has an excellent dielectric constant, but has a disadvantage in that optical properties including light transmittance are poor. On the other hand, the dielectric elastomer has a high light transmittance but a relative dielectric constant lower than that of the ferroelectric polymer. Therefore, the variable device 100 according to an embodiment of the present invention can be manufactured by dispersing the nanowire 112 including the ferroelectric polymer having high polarization degree and piezoelectricity in the dielectric elastomer 111, The electroactive layer 110 with improved relative dielectric constant can be provided. As a result, the driving displacement and the vibration intensity of the variable element 100 can be improved.

Meanwhile, in order to compensate the relative dielectric constant of the dielectric elastomer, a method of using a ferroelectric material such as a piezoelectric ceramics or metal nanoparticles as a filler can be considered. However, when an inorganic compound such as a piezoelectric ceramics is used as a filler and dispersed in a dielectric elastomer, there is a problem that the light transmittance of the variable element is greatly deteriorated because it is not sufficiently dispersed in the dielectric elastomer. In addition, when the metal nanoparticles are used as a high dielectric constant filler, there is a problem that the leakage current is generated by only a small amount of addition, and the performance of the variable element is greatly lowered. However, the nanowire 112 used in the variable device 100 according to an embodiment of the present invention can be dispersed in the dielectric elastomer more than the piezoelectric ceramics, so that the degradation of the light transmittance of the electroactive layer 110 can be minimized . In addition, unlike metal nanoparticles, nanowires do not have a conductivity and therefore do not generate leakage current.

Therefore, since the electroactive layer 110 of the variable element 100 according to the embodiment of the present invention is significantly larger than the electroactive layer composed of only the dielectric elastomer, the variable element 100 can improve the driving displacement of the variable element 100, The voltage can be lowered. In addition, since the variable element 100 according to an embodiment of the present invention has an excellent light transmittance as compared with an electroactive layer composed of a ferroelectric polymer or an electroactive layer including a dielectric elastomer and an inorganic filler or a metal filler, You may.

2 is a schematic cross-sectional view illustrating a touch sensing device according to an embodiment of the present invention. The contact-responsive element refers to an element capable of transmitting tactile feedback to a user in response to a user's touch to the contact-sensitive element.

Referring to FIG. 2, the touch sensing device 200 includes an electroactive layer 110, a plurality of first electrodes 221, and a plurality of second electrodes 222. The contact sensing element 200 shown in Fig. 2 is different from the variable element 100 shown in Figs. 1A and 1B in that the contact sensing element 200 shown in Figs. 1A and 1B The variable element 100 according to the present invention will not be described.

The electroactive layer 110 may transmit tactile feedback to a user in response to a user's touch. The electroactive layer 110 includes a dielectric elastomer 111 and a nanowire 112 made of a ferroelectric polymer. The specific details are substantially the same as those of the electroactive layer 110 of the variable element 100 shown in FIGS. 1A and 1B, and thus a detailed description thereof will be omitted.

A plurality of electrodes for applying an electric field to the electroactive layer 110 are disposed on both surfaces of the electroactive layer 110. The plurality of electrodes includes a plurality of first electrodes 221 and a plurality of second electrodes 222. The plurality of first electrodes 221 and the plurality of second electrodes 222 are made of a conductive material. In particular, the plurality of first electrodes 221 and the plurality of second electrodes 222 may be made of a transparent conductive material in order to secure the light transmittance of the touch sensing element 200. For example, the plurality of first electrodes 221 and the plurality of second electrodes 222 may be made of a transparent conductive material such as ITO, IZO, graphene, metal nanowires, and transparent conductive oxide (TCO). The first electrodes 221 and the plurality of second electrodes 222 may be formed of a metal mesh. That is, the plurality of first electrodes 221 and the plurality of second electrodes 222 may be formed of metal meshes in which a metal material is disposed in a mesh shape, and may be substantially transparent electrodes. However, the material constituting the plurality of first electrodes 221 and the plurality of second electrodes 222 is not limited to the above example, and may be composed of various transparent conductive materials.

The plurality of first electrodes 221 are disposed on one surface of the electroactive layer 110 and the plurality of second electrodes 221 are disposed on the other surface of the electroactive layer 110. For example, as shown in FIG. 2, a plurality of first electrodes 221 may be disposed on a lower surface of the electroactive layer 110, and a plurality of second electrodes 222 may be disposed on a lower surface of the electroactive layer . Each of the plurality of first electrodes 221 overlaps with each of the plurality of second electrodes 222. For example, as shown in FIG. 2, each of the plurality of first electrodes 221 overlaps with each of the plurality of second electrodes 222 in a one-to-one relationship. In this case, one of the overlapping regions where the plurality of first electrodes 221 and the plurality of second electrodes 222 overlap may be defined as one tactile cell. Here, the tactile cell is the smallest unit that can transmit tactile feedback to the user, and each tactile cell can independently transmit tactile feedback.

In some embodiments, the plurality of first electrodes 221 may extend in a first direction, and the plurality of second electrodes 222 may extend in a second direction that intersects the first direction. In this case, a crossing region where a plurality of first electrodes 221 and a plurality of second electrodes 222 cross each other can be defined as a tactile cell.

The touch sensing device 200 according to an embodiment of the present invention includes a plurality of electrodes 221 and 222 on both surfaces of the electroactive layer 110 to thereby form a plurality of tactile cells. Therefore, the plurality of tactile cells can cause the electroactive layer 110 to vibrate independently in each tactile cell. By independently applying different voltages to each of the plurality of electrodes 221 and 222, the contact sensing element 200 can transmit various feedbacks to the user.

It is advantageous that the touch sensitive element is disposed close to the position at which the user inputs the touch, in order to transmit a more direct touch to the user. Therefore, it is advantageous that the contact-sensitive element is disposed on the display panel and above the display panel. Therefore, sufficient transparency must be ensured so that the vibration intensity of the contact-sensitive element is improved and the quality of the image on the display panel is not deteriorated.

Accordingly, the touch sensing device 200 according to an embodiment of the present invention includes the electroactive layer 110 including the dielectric elastomer 111 and the nanowire 112 made of a ferroelectric polymer, thereby improving the dielectric constant and the piezoelectricity And has excellent light transmittance. In addition, the contact sensing device 200 according to an embodiment of the present invention has improved vibration strength as compared with a contact sensitive device using only a single dielectric elastomer, and has a significantly higher light transmittance than an inorganic filler or a metal filler as a ferroelectric filler great. Accordingly, the touch sensing device 200 according to an embodiment of the present invention can be positioned on the display panel, and can transmit a strong, diverse, and strong tactile feedback to the user.

3 is a flowchart illustrating a method of manufacturing a variable device according to an embodiment of the present invention. 4A is a schematic view for explaining a step of forming nanofibers in a method of manufacturing a variable element according to an embodiment of the present invention. 4B is a schematic view for explaining a nanofiber formed in the manufacturing method of the variable element according to the embodiment of the present invention. 4C is a schematic view for explaining a step of forming nanowires by pulverizing nanofibers in a method of manufacturing a variable element according to an embodiment of the present invention. The variable element manufactured by the method of manufacturing a variable element according to an embodiment of the present invention is substantially the same as the variable element 100 shown in FIGS. 1A and 1B, and thus a duplicate description will be omitted.

First, a polymer solution containing a ferroelectric polymer is formed (S310). The ferroelectric polymer, for example PVDF homopolymer, is supplied in powder form. The ferroelectric polymer may be dissolved in an organic solvent such as dimethyl formamide (DMF) or dimethyl sulfoxide (DMSO) to prepare a solution containing the ferroelectric polymer.

Subsequently, a polymer solution containing a ferroelectric polymer is electrospun to form a nanofiber made of a ferroelectric polymer (S320). Reference is now made to Figs. 4A and 4B together with a more detailed description of the step of forming the nanofibers.

Referring to FIGS. 4A and 4B, a nozzle 411 for electrospinning is filled with a solution 412 containing a ferroelectric polymer. For example, it can be filled in the nozzle 411 through a pump or the like. Thereafter, a first voltage is applied to the nozzle 411 and a second voltage is applied or grounded to the substrate 413 on which the nanowire emitted from the nozzle 411 is disposed under the nozzle 411 to be deposited. For example, when the substrate 413 is grounded, the first voltage applied to the nozzle 411 may be a high voltage. Here, the grounding of the substrate 413 may mean not only directly grounding the substrate 413 but also grounding the substrate supporting portion for supporting the substrate 413 during the manufacturing process. At this time, the substrate 413 on which the nanofibers 420 are to be deposited may be composed of a polyethylene terephthalate film or a silicon wafer, but is not limited thereto.

The electric field 414 is generated as the first voltage is applied to the nozzle 411 and the electric dipole 416 of the ferroelectric polymer in the solution state is aligned along the direction of the electric field 414 and the electric charge is biased. That is, while the solution-state ferroelectric polymer passes through the nozzle 411 to which the high voltage is applied, the anions are moved to the nozzle surface acting as the anode by gravity, and the cations dissolved in the solution are formed in the nozzle tip Moves by receiving repulsive force with liquid curved surface. This phenomenon is referred to as charge separation phenomenon. When the first voltage applied to the nozzle 411 is a high voltage, the mutual repulsive force of the electric force and the positive ions becomes larger than the surface tension of the solution, and droplets are split and radiated from the nozzle tip. At this time, the ferroelectric polymer emitted through the nozzle 411 may be charged with an electric charge having the same polarity as the first voltage. Here, a cone-shaped liquid curved surface is formed in the nozzle tip, which is called a Taylor cone. The radiated ferroelectric polymer 415 is moved toward the substrate 413 to which the second voltage having the opposite polarity to the first voltage is applied or grounded. The ferroelectric polymer is crystallized and deposited on the substrate 413 with the nanofibers 420 while the solvent evaporates before the ferroelectric polymer in solution in the electrospinning process reaches the substrate.

Referring to FIG. 4B, the nanofiber 420 refers to a fiber structure having a diameter of several tens to several hundreds nm. The nanofiber 420 has a long fiber structure having a length of several cm or more, unlike a nanowire having a length of several mu m. At this time, the nanofibers 420 manufactured through the electrospinning process may have a sheet shape.

At this time, the nanofibers 420 are arranged such that the dipoles are polarized in the longitudinal direction by the voltage applied by the electrospinning process. Specifically, the nanofibers 420 manufactured through the electrospinning process are crystallized by the strong voltage applied during the manufacturing process, and automatically have a? -Phase. Accordingly, the nanofiber 420 can have a high relative dielectric constant without extrusion, stretching, and poling processes, which are processes for imparting piezoelectricity to a commonly used PVDF polymer.

Next, the nanofibers 420 are freezed (S330) and pulverized to form nanowires (S340).

First, the step of freezing the nanofibers 420 (S330) helps the nanofibers 420 to be easily crushed by freezing the produced nanofibers 420 at extremely low temperatures. The temperature and time of the freezing process can be appropriately set according to the kind and size of the nanofiber. The step S330 of freezing the nanofibers 420 may be omitted in the form of the nanofibers 420 or for convenience of the process.

Then, the produced nanofibers 420 are pulverized to form nanowires (S340).

The nanofiber 420 itself is not only dissolved in a solvent but also is difficult to be dispersed in a dielectric elastomer, so that it is difficult to use the nanofiber 420 as a high dielectric constant filler. Therefore, the nanofibers 420 produced in the above-described steps may be pulverized to form nanowires having a length of several micrometers, thereby being dispersed in the dielectric elastomer.

Meanwhile, the step of freezing the nanofibers 420 and the step of crushing the nanofibers 420 can be continuously performed in the same space. Since the step of pulverizing the nanofibers 420 generates considerable heat, the crystals of the nanofibers 420 or polarized dipoles may be affected by the generated heat. However, by simultaneously performing the step of freezing the nanofibers 420 and the step of pulverizing the nanofibers 420, the heat generated during the pulverization process can be immediately cooled, and damage due to heat can be minimized.

Referring to FIG. 4C, the step S340 of freezing the nanofibers 420 (S330) and pulverizing them to form the nanowires may be performed through a freezing grinder.

First, a vial 423 containing the nanofibers 420 is stored in the low-temperature bath 431 to freeze the nanofibers 420. Thereafter, the vial 433 containing the nanofibers 420 is mounted in a chamber (not shown) wound around the magnetic field induction coil 435. The chamber is immersed in the low temperature bath 431 containing the liquid nitrogen 432 and a magnetic field is generated by the magnetic field induction coil 435 so that a steel impactor 434 existing in the vial 433 is moved to the left and right . The nanofiber 420 is pulverized by repeatedly moving the metal impactor 434.

Then, the prepared nanowire and the dielectric elastomer are mixed to form a mixture (S350). At this time, the nanowire and the dielectric elastomer may be mixed in an organic solvent such as hexane.

The step of forming the mixture may include mixing the nanowire and the dielectric elastomer such that the mixing ratio of the dielectric elastomer to the nanowire is from 99: 1 to 85:15. When the mixing ratio of the dielectric elastomer to the nanowire satisfies the above range, the light transmittance and the relative dielectric constant of the electroactive layer can be improved.

Subsequently, a mixture of the nanowire and the dielectric elastomer is coated to prepare an electroactive layer (S360).

For example, a mixture of a nanowire and a dielectric elastomer is coated on a substrate using a spraying method, a screen printing method, an inkjet method, a spin coating method, or a solution cating method. At this time, the mixture of the nanowire and the dielectric elastomer may be coated on a separate substrate such as a glass substrate to produce an electroactive layer independently, or may be directly coated on a metal to be electrode-like ITO.

By coating a mixture of the nanowire and the dielectric elastomer and then performing a drying treatment, an electroactive layer is produced. At this time, conditions such as specific temperature and time can be appropriately set according to the type and amount of the solvent.

Subsequently, electrodes are formed on at least one surface of the electroactive layer (S370).

The electrodes are formed in the electroactive layer in such a manner as sputtering, printing, slit coating and the like. At this time, the electrode may be formed on both sides of the electroactive layer, or may be formed only on one side. In addition, when the mixture of the nanowire and the dielectric elastomer is directly coated on the electrode to form the electroactive layer, the electrode can be formed through a separate process only on the opposite surface.

3 and 4A to 4C, the manufacturing method of the variable element 100 according to an embodiment of the present invention has been described. However, in the same manner as the method described above, (200) can be manufactured.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited by the following examples.

Example 1

A solution containing PVDF homopolymer (solef 6020, solvay) (refractive index: 1.48) is injected into the nozzle. A voltage was applied to the nozzle to apply an electric field of 10 ⁷ V / m between the nozzle and the substrate. Thereafter, the PVDF homopolymer is electrospinned from the nozzle to the grounded substrate to produce a sheet-like nanofiber. Thereafter, the prepared nanofibers were rapidly frozen at -196 캜 for 1 minute at -196 캜 for 5 minutes using a cryogenic freezer / mill (SPEX), and then, in a bath containing liquid nitrogen, The nanofibers were pulverized to prepare nanowires having a length of 10 m or less. At this time, the nanowire is in powder form.

The prepared nanowire made of PVDF homopolymer and PDMS (184 silicone elastomer, dow corning) as a dielectric elastomer were put into hexane as a solvent to prepare a mixed solution. At this time, the weight ratio of the nanowire consisting of PDMS and PVDF was 95: 5. The mixture solution was cast on the ITO electrode solution and then dried to obtain an electroactive layer having a thickness of 100 占 퐉. Thereafter, ITO was slit coated on the opposite surface of the prepared electroactive layer to produce a variable device having transparent electrodes on both sides.

Example 2

A variable device was fabricated in the same manner as in Example 1, except that the weight ratio of the nanowire consisting of PDMS and PVDF was 90:10.

Example 3

A variable device was fabricated in the same manner as in Example 1 except that the weight ratio of the nanowire consisting of PDMS and PVDF was 85:15.

Comparative Example 1

PDMS was cast on the ITO electrode by solution casting and then dried to obtain an electroactive layer having a thickness of 100 mu m and containing no nanowires. Thereafter, ITO was slit-coated on the other surface of the prepared electroactive layer to produce a variable device having transparent electrodes on both sides.

Comparative Example 2

Barium titanate (particle diameter: 120 nm) as an inorganic filler was mixed with PDMS and hexane as a solvent to prepare a mixed solution. At this time, the weight ratio of PDMS to barium titanate was 95: 5. Thereafter, the mixed solution was solution cast on the ITO electrode and then dried to obtain an electroactive layer having a thickness of 100 탆. ITO was slit coated on the other surface of the prepared electroactive layer to fabricate a variable device having transparent electrodes on both sides.

Comparative Example 3

A variable element was prepared in the same manner as in Example 1, except that PVDF homopolymer (solef 6020, solvay) powder as a filler was used as a filler instead of the nanowire made of PVDF homopolymer.

Comparative Example 4

A variable device was fabricated in the same manner as in Comparative Example 3, except that the weight ratio of PDMS and particulate PVDF homopolymer was 90:10.

Comparative Example 5

PVDF homopolymer (solef 6020, solvay) was co-extruded and uniaxially stretched. The stretched PVDF film was subjected to a poling process of 100 V / 탆 to form a PVDF film having piezoelectricity. Thereafter, the stretched PVDF film was pulverized using a cryogenic freezer / mill (SPEX) to prepare fine particles of a PVDF homopolymer.

The mixed solution was prepared by adding PDMS (184 silicone elastomer, dow corning) as a solvent and DMSO as a fine particle made of the PVDF homopolymer and a dielectric elastomer. At this time, the weight ratio of the fine particles made of PDMS and PVDF was 95: 5. The mixture solution was cast on the ITO electrode solution and then dried to obtain an electroactive layer having a thickness of 100 占 퐉. Thereafter, ITO was slit-coated on the other surface of the prepared electroactive layer to produce a variable device having transparent electrodes on both sides.

Comparative Example 6

A variable device was manufactured in the same manner as in Comparative Example 5 except that the weight ratio of the fine particles made of PDMS and PVDF was 90:10.

Comparative Example 7

A variable device was fabricated in the same manner as in Comparative Example 5, except that the weight ratio of the fine particles made of PDMS and PVDF was 85:15.

Experimental Example 1 - Measurement of relative dielectric constant

The relative dielectric constants of the variable devices manufactured according to Examples 1 to 3 and Comparative Examples 1 to 7 were measured using a LCR meter 4284A by measuring the capacitance at a frequency of 150 kHz using the following equation . The measurement results are shown in Table 1 below.

[Equation 1]

? _r = C xt / A

(? _r : specific dielectric constant, C: capacitance, t: thickness of the electroactive layer, A:

Experimental Example 2 - Measurement of light transmittance

The light transmittances of the variable elements manufactured according to Examples 1 to 3 and Comparative Examples 1 to 7 were measured using a haze meter (JCH-300S, Oceanoptics). The measured light transmittance is an average value of the light transmittance measured in the visible light region (400 nm to 750 nm), and the measurement results are shown in Table 1 below.

division Composition of electroactive layer Relative dielectric constant
(at 150kHz) Light transmittance
(%) Dielectric elastomer filler Weight ratio Example 1 PDMS PVDF nanowires 95: 5 2.6 88 Example 2 PDMS PVDF nanowires 90:10 2.8 84.1 Example 3 PDMS PVDF nanowires 85:15 3.2 81.6 Comparative Example 1 PDMS - - 1.8 91 Comparative Example 2 PDMS Barium titanate 95: 5 3.4 42.9 Comparative Example 3 PDMS PVDF homopolymer 95: 5 2.0 87.1 Comparative Example 4 PDMS PVDF homopolymer 90:10 2.1 86.1 Comparative Example 5 PDMS Fine particles of stretched PVDF 95: 5 2.1 85.8 Comparative Example 6 PDMS Fine particles of stretched PVDF 90:10 2.1 84.4 Comparative Example 7 PDMS Fine particles of stretched PVDF 85:15 2.2 82.3

As shown in Table 1, it can be seen that the dielectric constant of Examples 1 to 3 is significantly higher than that of Comparative Example 1, which does not include nanowires made of PVDF.

In comparison between Example 1 and Comparative Example 2, when the barium titanate as the metal filler is dispersed in the dielectric elastomer, the relative dielectric constant increases, but it is confirmed that the light transmittance is greatly reduced to 50% or less. That is, when barium titanate is used, the light transmittance of the variable element is significantly deteriorated and the variable element can not be used on the display panel.

In comparison between Examples 1 to 3 and Comparative Examples 3 to 7, it can be seen that the relative dielectric constant is greatly improved only when nanowires made of PVDF are used. Specifically, when the PVDF homopolymer is simply dispersed in the dielectric elastomer, the relative dielectric constant is improved finely, but the effect of improving the relative dielectric constant is insufficient as compared with Examples 1 to 3. Further, even in the case of a film of stretched PVDF having a? -Phase and a high dielectric constant, which is subjected to a stretching process and a poling process, when dispersed in a particulate form in a dielectric elastomer through a pulverizing process, a paraffin such as a nanowire made of PVDF It can be confirmed that the effect of improving the electric conductivity can not be obtained.

5 is a schematic exploded perspective view for explaining a structure of a display device 500 including a variable element according to an embodiment of the present invention. 5, a display device 500 according to an exemplary embodiment of the present invention includes a lower cover 510, a variable element 100, a display panel 520, a touch panel 530, and an upper cover 540 .

The lower cover 510 is disposed under the display panel 520 so as to cover the lower portion of the display panel 520, the variable element 100 and the touch panel 530. The lower cover 510 protects the inside of the display apparatus 500 from external impacts and penetration of foreign matter or moisture. For example, the lower cover 510 may be made of a material such as, but not limited to, thermoformable and workable plastic. The lower cover 510 may be made of a material that can be deformed together with the shape of the display device 500 as a flexible display device is actively developed. For example, the lower cover 510 may be made of a material such as plastic having ductility.

The variable element 100 is disposed on the lower cover 510 and disposed below the display panel 520. [ The specific components of the variable element 100 are substantially the same as those of the variable element 100 shown in Figs. 1A and 1B, and thus redundant description will be omitted. The electroactive layer 110 of the variable device 100 according to an embodiment of the present invention has a larger relative dielectric constant than the electroactive layer of the conventional variable element using only the dielectric elastomer as the electroactive layer. Therefore, the variable element 100 is disposed under the display panel 520, so that the driving displacement, that is, the bending performance is further improved, and the driving voltage can be reduced.

The display panel 520 means a panel in which a display device for displaying an image on the display device 500 is disposed. As the display panel 520, for example, various display panels such as an organic light emitting display panel, a liquid crystal display panel, an electrophoretic display panel and the like can be used. The display panel 520 may be an organic light emitting display. An organic light emitting display device is a display device that allows an organic light emitting layer to emit light by causing a current to flow through the organic light emitting layer, and emits light of a specific wavelength using an organic light emitting layer. The organic light emitting display includes at least a cathode, an organic light emitting layer, and an anode.

The organic light emitting display device can also be configured to be flexible and deformable. That is, the organic light emitting display device is a flexible organic light emitting display device having flexibility and includes a flexible substrate. The flexible organic light emitting display device can be deformed in various directions and angles by an external force.

A touch panel 530 is disposed on the display panel 520. The touch panel 530 refers to a panel that senses a user's touch input to the display device 500 and provides touch coordinates.

The touch panel 530 may be classified according to the position in which it is disposed. For example, an add-on method of attaching the display panel 520 to the upper surface of the display panel 520, an on-cell method of depositing the display panel 520 on the display panel 520, An in-cell system formed on the substrate. Also, the touch panel 530 may be classified according to the operation mode. For example, a capacitive type, a resistive type, an ultrasonic type, an infrared type, and the like can be used.

The upper cover 540 is disposed on the touch panel 530 so as to cover the upper side of the variable element 100, the display panel 520 and the touch panel 530. The upper cover 540 may perform the same function as the lower cover 510. The upper cover 540 may be made of the same material as the lower cover 510.

5, an adhesive layer for adhering the lower cover 510, the variable element 100, the display panel 520, the touch panel 530, and the upper cover 540 to each other may be used. The adhesive layer may be, for example, an optical clear adhesive (OCA) or an optical clear resin (OCR), but is not limited thereto.

The display device 500 according to an embodiment of the present invention uses the variable element 100 including the electroactive layer 110 having a high dielectric constant, thereby lowering the driving voltage and improving the driving displacement.

6 is a schematic exploded perspective view illustrating a display device including a touch sensitive device according to an embodiment of the present invention. 6, the display device 600 shown in FIG. 6 includes a touch sensitive device 200, and FIG. 5 shows a state in which the touch sensitive device 200 is placed on the display panel 520 Is the same as that of the display device 500 shown in FIG.

The touch sensitive device 200 is disposed on the display panel 520 and disposed under the touch panel 530. The specific components of the contact-sensitive element 200 are substantially the same as those of the contact-sensitive element 200 shown in FIG. 2, so duplicate descriptions are omitted.

The touch sensing device 200 according to an embodiment of the present invention has a significantly higher light transmittance than a touch sensitive device using a metal oxide such as lead zirconate titanate or barium titanate as a filler, And can be used as a contact-sensitive device that can transmit a variety of touch senses directly to a user.

The display device 600 shown in FIG. 6 has improved vibration strength by using the contact-sensitive element 200 including the electroactive layer 110 having a superior dielectric constant. In addition, the display device 600 can arrange the touch sensing device 200 having an excellent light transmittance on the front surface of the display panel 520. Thus, the display device 600 can transmit the touch feeling and feedback directly to the user by placing the contact-sensitive device 200 with improved vibration intensity close to the user.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: variable element
110: electric active layer
121: first electrode
122: second electrode
200: Contact-sensitive element
221: a plurality of first electrodes
222: a plurality of second electrodes
500, 600: Display device
510: Lower cover
520: Display panel
530: Touch panel
540: upper cover

Claims (14)

An electroactive layer made of a dielectric elastomer in which a nanowire is dispersed; And
And an electrode disposed on at least one surface of the electroactive layer. The method according to claim 1,
The nanowire is made of a ferroelectric polymer. Contact sensitive device. The method according to claim 1,
The diameter of the nanowire is 10 nm to 500 nm,
And the length of the nanowire is 1 占 퐉 to 10 占 퐉. The method according to claim 1,
Wherein the nanowire has a structure of? -Phase. The method according to claim 1,
The dielectric elastomer is polydimethyl siloxane (PDMS)
Wherein the nanowire has a refractive index of 1.35 to 1.55. 3. The method of claim 2,
Wherein the ferroelectric polymer is a polyvinylidene fluoride (PVDF) polymer. The method according to claim 1,
Wherein the weight ratio of the dielectric elastomer to the nanowire is from 99: 1 to 85:15. The method according to claim 1,
Wherein the contact sensitive element has a light transmittance to a visible light region of 80% or more. Display panel; And
And a contact-sensitive element on the display panel,
Wherein the contact sensitive element has an electroactive layer made of a dielectric elastomer in which nanowires are dispersed and an electrode disposed on at least one surface of the electroactive layer. 10. The method of claim 9,
Wherein the nanowire is made of a ferroelectric polymer. 10. The method of claim 9,
Further comprising a touch panel on the display panel,
Wherein the touch sensitive element is a contact sensitive element disposed between the display panel and the touch panel. Electrospinning a polymer solution containing a ferroelectric polymer to form a nanofiber made of a ferroelectric polymer;
Pulverizing the nanofibers to form nanowires;
Mixing the nanowire and the dielectric elastomer to form a mixture; And
And coating the mixture to form an electroactive layer. 13. The method of claim 12,
Wherein forming the nanowire comprises:
Further comprising the step of freezing the nanofibers prior to crushing the nanofibers. 13. The method of claim 12,
Wherein the forming the mixture comprises mixing the nanowire and the dielectric elastomer such that the mixing ratio of the dielectric elastomer to the nanowire is from 99: 1 to 85:15.

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