KR20160080071A - Display device - Google Patents

Abstract

Provided is a display device. The display device includes: a display panel; a contact sensing device on the display panel; and a linear polarizing plate on the contact sensing device. The contact sensing device includes an electroactive layer elongated along a first axis and formed to delay a phase of an incident light. According to an embodiment of the present invention, the display device includes the contact sensing device having the electroactive layer formed to delay the phase of the incident light. A separate phase delay film for repressing the reflection of an external light can be omitted. Therefore, the display device can be thin and manufacturing costs of the display device can be reduced.

Description

Display device {DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a display device including a touch sensitive device having both an external light reflection suppressing function and a tactile feedback providing function.

The touch panel is a device for detecting a user's touch input such as a screen touch or a gesture on a display device, and is used for a portable display device such as a smart phone or a tablet PC, a display device of a public facility, Devices. Examples of the operation method of the touch panel include a resistive method, a capcitive method, an optical method, and an electro-magnetic (EM) method.

However, in recent years, it has been proposed to use a haptic effect that not only senses a user's touch input but also transmits tactile feedback that can be felt by a user's finger or a user's stylus pen with feedback on a touch input of the user Research on touch panel is under way.

Conventionally, the haptic effect is implemented by transmitting vibration to a user by using an eccentric motor or the like. Recently, a contact-sensitive device realized in the form of a film by using Electro-Active Polymers (EAP) has received attention.

However, since the contact-sensitive device using the electroactive polymer is driven by electric stimulation, a strong electric field may be applied to the electroactive layer composed of the electroactive polymer, and the strong electric field applied to the electroactive layer may cause other structures Interference may occur.

On the other hand, with the development of portable display devices, consumer expectations for convenience in outdoor environments are increasing. Particularly, there is a problem of visibility reduction due to reflection of light coming from the outside, and additional components such as a phase retardation film have been developed, but they have encountered limitations such as weight reduction and thinning and increase manufacturing cost.

Haptic feedback screen using piezoelectric polymer (Patent Application No. 10-2013-0023058)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device having a thin thickness and a low external light reflectance by using an electroactive layer having both a piezoelectric property and a phase retardation effect for generating a haptic effect.

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 display device including a display panel, a touch sensitive device on a display panel, and a linear polarizer on a touch sensitive device. The contact-sensitive element includes an electroactive layer which is uniaxially stretched and configured to retard the phase of the incident light. Here, the electro-active layer may be configured to delay the phase of the incident light by about? / 4. The electroactive layer may be formed of PVDF (polyvinylidene fluoride) -based polymer. Here, the thickness of the electroactive layer may be 40 占 퐉.

According to another aspect of the present invention, there is provided a display device including a display panel, a linear polarizer on a display panel, and a contact sensitive device. The contact-sensitive element includes an electroactive layer disposed between the display panel and the linear polarizer and having a stretching axis inclined at a predetermined angle from the polarization axis of the polarizer.

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

The present invention can omit additional components such as a separate phase retardation film for minimizing the reflection of external light by retarding the phase of the incident light by using the electroactive layer which is uniaxially stretched and has the refractive index anisotropic property, Can be reduced. In addition, since additional components are omitted, it is effective in cost reduction.

In addition, the present invention minimizes the interference of the touch signal of the touch panel due to the electric field applied to the electric active layer by disposing the linear polarizer between the touch sensitive device and the touch panel and using the linear polarizer as the shielding layer have.

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

1 is a schematic exploded perspective view for explaining a display device according to an embodiment of the present invention.
2 is a schematic cross-sectional view illustrating a display device according to an embodiment of the present invention.
3A and 3B are schematic perspective views illustrating a phase delay effect of an electroactive layer provided in a touch sensing device of a display device according to an embodiment of the present invention.
4 is a graph showing reflectance of an electroactive layer of a display device according to an embodiment of the present invention.
5 is a schematic cross-sectional view illustrating a display device according to another embodiment of the present invention.
Figure 6 is an illustration of examples in which a display device according to various embodiments of the present invention may be advantageously utilized.

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.

It is to be understood that 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.

In the present specification, the electroactive layer refers to a layer capable of transmitting a sense of vibration by deforming its shape as voltage is applied.

In this specification, a contact-sensitive element means an element capable of transmitting tactile feedback to a user in response to a user's contact with the contact-sensitive element.

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

1 is a schematic exploded perspective view for explaining a display device according to an embodiment of the present invention. 2 is a schematic cross-sectional view illustrating a display device according to an embodiment of the present invention. For convenience of explanation, each component provided in the display apparatus 100 is schematically shown in a rectangular shape, and various components provided in the display panel 110 are not shown in detail. 1 and 2, a display device 100 includes a display panel 110, a touch sensitive device 120, a linear polarizer 130, and a cover window 140. [

The display panel 110 displays an image, and includes a plurality of pixels. The pixel of the display panel 110 may be composed of various elements. For example, when the display device 100 is an organic light emitting display, the pixels of the display panel 110 may include an organic light emitting diode (OLED). Meanwhile, the pixels of the display panel 110 may include thin film transistors, capacitors, and wirings connected to the organic light emitting diodes in addition to the organic light emitting diodes.

According to some embodiments, the display panel 110 may have flexibility. In this case, a thin-film pixel may be formed on a substrate made of a polyester-based polymer, a silicon-based polymer, an acrylic-based polymer, a polyolefin-based polymer, or the like.

The display panel 110 includes at least one reflective layer. For example, when the display panel 110 is an organic light emitting display panel used in a top emission type organic light emitting display, the anode of the organic light emitting diode provided in the display panel 110 functions as a reflective layer. do. In this case, the anode of the organic light emitting diode may be a transparent conductive layer such as ITO or IZO and a transparent conductive layer such as Ag, Ni, Au, Pt, Al, Cu, And an aluminum neodymium (Mo / AlNd) reflective layer. In this case, the light emitted from the organic light emitting diode is reflected by the reflective layer of the anode and emitted toward the top surface of the display panel 110. In addition, when the display panel 100 is an organic light emitting display panel used in a bottom emission type organic light emitting display, the cathode of the organic light emitting diode functions as a reflective layer. In this case, the cathode of the organic light emitting diode may be made of magnesium (Mg), silver (Ag), or an alloy thereof (MgAg). Since the materials described above have a high reflectivity, the anode or the cathode of the organic light emitting diode can have a high reflectance. However, the reflective layer is not limited to the anode or the cathode, and all configurations of the display panel 110 having a high reflectance may be referred to as a reflective layer. For example, reflection can also be generated on the surface of a color filter for realizing the color of the display panel 110, or on the surface of a black matrix for distinguishing between pixels and pixels, and the like, Lt; / RTI >

The touch sensitive device 120 is disposed on the display panel 110 and generates tactile feedback to generate a haptic effect on the display device 100. [ The contact-sensitive element includes an electroactive layer 122, a plurality of first electrodes 121, and a plurality of second electrodes 123.

The plurality of first electrodes 121 and the plurality of second electrodes 123 are disposed on at least one surface of the electroactive layer 122 and are formed on the upper surface of the electroactive layer 122, All of which can be disposed on the lower surface. For example, the first electrode 121 is disposed on the lower surface of the electroactive layer 122, and the second electrode 123 is disposed on the upper surface of the electroactive layer 122. The first electrode 121 and the second electrode 123 extend in different directions and a different voltage is applied to the first electrode 121 and the second electrode 123. The electroactive layer 122 may vibrate based on an electric field generated between the first electrode 121 and the second electrode 123 in a region where the first electrode 121 and the second electrode 123 intersect.

According to some embodiments, the plurality of first electrodes 121 and the plurality of second electrodes 123 may be disposed on only one side of the electroactive layer 122. In this case, the first electrode 121 and the second electrode 123 are spaced apart from each other and disposed on the same plane, and a different voltage may be applied to the first electrode 121 and the second electrode 123. The electroactive layer 122 can vibrate based on the electric field formed by the first electrode 121 and the second electrode 123. [

The plurality of first electrodes 121 and the plurality of second electrodes 123 may be formed of a conductive material having excellent transmittance. For example, the first electrode 121 and the second electrode 123 may be made of a transparent conductive material such as ITO (Indium Tin Oxide), PEDOT: PSS, silver-nanowire (AgNW), or the like. In addition, the first electrode 121 and the second electrode 123 may be formed of a metal mesh. In this case, the first electrode 121 and the second electrode 123 can be substantially transparent since light can be transmitted between the metal lines in the form of a mesh. The first electrode 121 and the second electrode 123 may be made of the same material or different materials. Each of the first electrode 121 and the second electrode 123 may have a single-layer structure or a multi- Structure.

The electroactive layer 122 is a plate-like film made of electro-active polymers (EAP), which is a polymer material deformed by electrical stimulation. For example, the electroactive layer 122 may be formed of a ferroelectric polymer of PVDF (Polyvinylidene fluoride) series. Specifically, the electroactive layer 122 may be made of PVDF, which is a homopolymer of vinylidene fluoride (VF 2) monomer, or may be made of P (VDF-TrFE) poly [(vinylidenefluoride-co-trifluoroethylene) When the active layer 122 is made of a ferroelectric polymer, the alignment direction of the dipole in the electroactive layer 122 is changed as the voltage is applied to the electroactive layer 122, so that the contact sensitive device 120 can vibrate .

The electroactive layer 122 may transmit tactile feedback in units of a plurality of cells. As shown in FIGS. 1 and 2, when a plurality of first electrodes 121 and a plurality of second electrodes 123 intersect each other, a plurality of cells may include a plurality of first electrodes 121, And the two electrodes 123 intersect with each other. In this case, a different voltage is applied to each of the plurality of first electrodes 121, and a different voltage is applied to each of the plurality of second electrodes 123. Accordingly, electric fields different from each other can be formed in the intersection regions where the plurality of first electrodes 121 and the plurality of second electrodes 123 cross each other. In this case, the electroactive layer 122 can vibrate at different frequencies in the crossing regions, and can transmit independent tactile feedback on a plurality of cell basis.

The area of each of the plurality of cells can be determined in consideration of the size of a finger of a general person. For example, the area of each of a plurality of cells may have an area of 2 cm x 2 cm. Since the electroactive layer 122 transmits tactile feedback in units of a plurality of cells, the contact sensitive device 120 can provide various and detailed haptic effects to the user.

The electroactive layer 122 may be uniaxially stretched along a specific direction. For example, by applying a tensile force to the electroactive layer 122 in a specific stretching axis direction, the electroactive layer 122 can be uniaxially stretched. As the electroactive layer 122 is uniaxially stretched, the electroactive layer 122 has different refractive indexes depending on the direction of the crystal. The phase of the incident light incident on the electroactive layer 122 is changed based on the crystalline anisotropy of the refractive index of the electroactive layer 122.

As the electroactive layer 122 is uniaxially stretched along a specific direction, the electroactive layer 122 has a refractive index anisotropy, so that the phase of the incident light incident on the electroactive layer 122 can be delayed. The display device 100 according to an embodiment of the present invention can suppress the reflection of external light by using the optical characteristic of the electroactive layer 122. [ Specifically, the electroactive layer 122 may function as a phase retardation film under the linear polarizer 130. [

However, in order for the electroactive layer 122 to be used as an external light reflecting film, certain conditions must be satisfied. Generally, the external light reflection film is formed by the structure of the linear polarizer 130, the phase retardation film and the reflection layer, and the phase retardation film is formed so as to retard the phase of the incident light having the wavelength of? By? / 4. In this case, the light incident on the linear polarizer 130 can be changed in optical characteristics into light polarized in a direction perpendicular to the polarization axis of the linear polarizer 130 through the phase retardation film and the reflection layer, So that the external light reflection effect can be maximized. Therefore, in order for the electroactive layer 122 disposed below the linear polarizer 130 to function as a phase retardation film, the phase of the incident light must be delayed by? / 4 like a phase retardation film applied to a general external light reflective film. The phase delay value of the electric active layer 122 can be determined based on the thickness and elongation of the electroactive layer 122. [

Specifically, the phase delay value of the electric active layer 122 satisfies the following expression (1).

(? _Eff : effective refractive anisotropy, d: thickness of the electroactive layer, lambda: wavelength of incident light)

In Equation (1),? _Neff represents the effective refractive anisotropy of the electroactive layer 122 and may be referred to as birefringence. The effective refractive anisotropy value of the electroactive layer 122 is an element representing the degree of the refractive index anisotropic characteristic of the electroactive layer 122, which is determined by the constituent material of the electroactive layer 122 and the elongation. Thus, the as expressed in Equation 1, the phase delay value of the electric active layer (122) (λ / 4) are electric active layer (122 determining an effective refractive anisotropic value of the electric active layer (122) (Δn _eff) ), The elongation percentage, and the thickness (d) of the electroactive layer 122. The phase delay value? / 4 of the electric active layer 122 will be described later with reference to [Table 1].

On the other hand, the electroactive layer 122 has a high transmittance in order to minimize a decrease in visibility of the display device 100. [ That is, the reflectivity of the electroactive layer 122 is low. For example, the reflectance of the electroactive layer 122 may be less than 6%. In this case, most of the light incident on the electroactive layer 122 passes through the electroactive layer 122, and the phase may be delayed in the process of passing through the electroactive layer 122. A detailed description of the reflectance of the electroactive layer 122 will be described later with reference to FIG.

The linear polarizer 130 is disposed on the contact sensitive element 120. The linear polarizer 130 is implemented with a structure in which a polarizer is interposed between the upper and lower support layers. The polarizer controls the amount of light transmitted according to the degree of polarization of the incident light. The polarizer can be formed, for example, of a film made of PVA (Poly Vinyl Alcohol), and can be formed by stretching a PVA film absorbing iodine with a strong tension. The support layer provided on the upper and lower sides of the polarizer may be formed of a film of TAC (TriAcetyl Cellulose) for protecting and supporting the PVA film. However, the structure and material of the linear polarizer 130 are not limited thereto. At least one supporting layer may be omitted in the linear polarizer 130, and a polarizer may be coated on one supporting layer to form a thin crystal film ploarizer may be formed.

The linear polarizer 130 selectively transmits or absorbs light having a specific polarization state among incident light having various polarization states. For example, the linear polarizer 130 selectively transmits light polarized in a direction parallel to the polarization axis.

The polarization axis of the linearly polarizing plate 130 and the elongation axis of the electroactive layer 122 may be at a predetermined angle. For example, the angle formed by the polarization axis of the linear polarizer 130 and the elongate axis of the electroactive layer 122 is about 45 degrees or about 135 degrees. Herein, about 45 ° means one angle selected from the range of 43 ° to 47 °, and about 135 ° means one angle selected from the range of 133 ° to 137 °. That is, since a general process error that can be generated in the process of disposing the linear polarizer 130 on the touch sensing device 120 is ± 2 °, the polarization axis of the linear polarizer 130 and the stretching axis The angle formed may be an angle selected from the range of 43 DEG to 47 DEG or an angle selected from the range of 133 DEG to 137 DEG. When the linear polarizer 130 and the electroactive layer 122 are disposed at the above-described angles, the reflection of external light generated by the reflective layer of the display panel 110 can be minimized. This will be described later with reference to Figs. 3A and 3B.

The cover window 140 is disposed on the linear polarizer 130. The cover window 140 is a substrate for protecting the components of the display device 100 from the external environment. The cover window 140 may be formed of a glass having a high transmittance so that light emitted from the display panel 110 can be transmitted through the film or a film made of an organic or inorganic composite material having a hardness of 5H or more and an excellent transmittance .

1 and 2, a first adhesive layer is disposed between the display panel 110 and the contact sensitive element 120 to adhere the display panel 110 to the contact sensitive element 120, A second adhesive layer is disposed between the touch sensitive device 120 and the linear polarizer 130 so as to adhere the linear polarizer 130 and the linear polarizer 130, 3 adhesive layer may be disposed between the linear polarizer 130 and the cover window 140. [ The first adhesive layer to the third adhesive layer may be made of SVR (Super View Resin) or OCA (Optically Clear Adhesive) as an adhesive material having high adhesive force and high light transmittance, but the present invention is not limited thereto.

Since the electric active layer 122 of the touch sensing device 120 provided in the display device 100 according to the embodiment of the present invention can delay the phase of the incident light, the electric active layer 122 functions as a phase retardation film . To describe this in more detail, reference is made to FIGS. 3A and 3B together.

FIGS. 3A and 3B are schematic perspective views illustrating a phase delay effect of an electroactive layer included in a touch sensing device of a display device according to an exemplary embodiment of the present invention. 3A and 3B, components of the display device 100 other than the linearly polarizing plate 130, the active layer 122, and the reflective layer 111 of the display panel 110 are omitted for convenience of description, The movement path is indicated by a dashed arrow and the polarization state of light is indicated by a solid line arrow. 3A to 3B, the shape of the reflective layer 111 is shown in the form of a plate for convenience of explanation. 3A and 3B, the polarizing axis PA of the linear polarizer 130 and the extending axis EA of the electroactive layer 122 are hatched.

Referring to FIG. 3A, the light L ₁ entering from the outside of the display device 100 passes through the cover window 140 on the display device 100 and enters the linear polarizer 130.

The light L ₁ entering from the outside of the display device 100 has various polarization states. The linear polarization plate 130 selectively absorbs or transmits only light L ₂ having a specific polarization state among light L ₁ having various polarization states. Thus, the light L ₂ having passed through the linear polarizer 130 has a specific polarization state. For example, as shown in FIG. 3A, the linear polarizer 130 can transmit light having a polarization state parallel to the polarization axis PA. Therefore, the light L ₂ having passed through the linear polarizer 130 has a polarization state parallel to the flat optical axis PA.

The light L ₂ passing through the linear polarizer 130 is incident on the electroactive layer 122 of the contact-sensitive element 120.

Since the second electrode 123 of the contact sensitive device 120 is made of a transparent conductive material, the light L ₂ passing through the linear polarizer 130 passes through the second electrode 123 of the contact sensitive device 120 And can reach the electroactive layer 122 of the contact sensitive element 120. [ As described above, the electroactive layer 122 can be uniaxially stretched in the direction of the stretching axis (EA), and the angle formed by the stretching axis EA of the electroactive layer 122 and the polarizing axis PA of the linear polarizing plate 130 ([alpha]) is 45 [deg.] or 135 [deg.]. The light L ₃ that has passed through the active layer 122 of the contact sensitive device 120 is transmitted through the contact layer 120 of the contact sensitive device 120, The phase is delayed with respect to the light L ₂ before passing through the electric active layer 122. In this case, the transmittance of the electroactive layer 122 can be determined by the following equation (2).

D is the thickness of the electroactive layer 122, and? _Eff (n) is the thickness of the electroactive layer 122, and T is the transmittance of the electroactive layer 122, and α is the angle between the polarization axis PA of the linear polarizer 130 and the elongation axis EA of the electroactive layer 122, : Effective refractive anisotropy value of the electroactive layer 122, and?: Wavelength of incident light)

If the angle alpha between the elongation axis EA of the electroactive layer 122 of the contact sensitive element 120 and the polarization axis PA of the linear polarizer 130 is 45 or 135 degrees (i.e.,? / 4 or? 3? / 4), the sin ² (2?) Value of the above expression (2) becomes 1. On the other hand, if the thickness d of the electroactive layer 122 and the elongation are optimized to delay the phase of the incident light by? / 4, the value of sin ² ( ² ? D? N _eff /?) That is, since d · Δn _eff = λ / 4 from the above equation (1), sin ² (2πdΔn _eff / λ) = sin ² (π / 2) = 1. As a result, the transmittance T of Equation (2) becomes 1, so that all the light L ₂ incident on the electroactive layer 122 is transmitted and its phase is delayed by? / 4.

The light L ₃ that has passed through the electroactive layer 122 reaches the reflective layer 111 of the display panel 110. As described above, the reflective layer 111 refers to a component that has a high reflectivity in the display panel 110 and can reflect external light. For example, the reflective layer 111 may include an anode of the organic light emitting diode, various metal wires included in the display panel 110, a surface of a color filter for realizing the color of the display panel 110, Lt; RTI ID = 0.0 > black matrix. ≪ / RTI >

Referring to FIG. 3B, the light L ₃ reaching the reflective layer 111 of the display panel 110 is reflected by the reflective layer 111.

The light L ₃ reaching the reflective layer 111 of the display panel 110 is reflected by the reflective layer 111 and changes in phase by 180 °. The phase of the light L ₄ reflected by the reflective layer 111 has a phase difference of 180 ° from the phase of the light L ₃ transmitted through the electric active layer 122 of the contact sensitive device 120. Although other components such as the first electrode 121 of the contact sensitive element 120 may be disposed between the electroactive layer 122 of the contact sensitive element 120 and the reflective layer 111 of the display panel 110 The components disposed between the active layer 122 of the contact sensitive device 120 and the reflective layer 111 of the display panel 110 have a high transmittance so that the active layer 122 of the contact sensitive device 120 Most of the light L _{3 that has} passed through it can reach the reflective layer 111 of the display panel 110.

Then, the light L ₄ reflected by the reflective layer 111 is incident on the electroactive layer 122 of the contact-sensitive element 120 again.

The light L ₄ incident on the electric active layer 122 is delayed again by? / 4 while passing through the electric active layer 122. That is, the light L ₃ that has first passed through the electroactive layer 122 of the contact sensitive device 120 has a phase delayed by? / 4 from the phase of the light L _{2 that} was initially incident on the electroactive layer 122, The light L ₄ reflected by the reflective layer 111 has a phase inverted by 180 degrees (i.e.,? Radian) from the phase of the light L ₃ before being reflected, L ₅ has a phase delayed by? / 4 from the phase of the reflected light L ₄ . As a result, the light L ₅ having passed through the electroactive layer 122 again has a phase delayed by? / 2 from the phase of the light L ₂ first incident on the electroactive layer 122, And becomes polarized light in a direction perpendicular to the polarization axis.

Then, the light L ₅ having passed through the electroactive layer 122 reaches the linear polarizer 130.

As described above, since the linear polarizer 130 transmits light parallel to the polarization axis PA, the light L ₅ passing through the electroactive layer 122 can not pass through the linear polarizer 130, (130). As a result, the light (L ₁₎ flows on the outside of the display device 100 is reflected, and the reflection of external light that is again emitted to the outside can be minimized, and thus can improve the visibility of the display device 100.

That is, the electroactive layer 122 delays the phase of the incident light L2 by? / 4 so that the elongation axis EA of the electroactive layer 122 and the polarization axis PA of the linear polarizer 130 are about 45 degrees or about When tilted by 135 °, the light L ₁ introduced from the outside is reflected again and is not emitted to the outside. As described above, since the phase delay value of the electroactive layer 122 can be determined by the constituent material of the electroactive layer 122, the elongation and the thickness, the electroactive layer 122 can delay the phase by? / 4 The thickness and elongation of the electroactive layer 122 can be optimized.

Specifically, the thickness and the elongation percentage of the electroactive layer 122 can be optimized so that the phase delay value of the electroactive layer 122 is about? / 4. Here, about? / 4 includes an error range of? 5 to? 5 nm. That is, about λ / 4 means one value selected from the range of λ / 4 - 5 nm to λ / 4 + 5 nm, which reflects a minute error that may occur in the process.

Generally, when the electric active layer 122 has a phase delay value of? / 4-5 nm to? / 4 + 5 nm, the light L ₅ reflected by the reflection layer 111 and passing through the electric active layer 122 Most of the light is intercepted by the linear polarizer 130 and the light emitted through the linear polarizer 130 is minute and may not be visually recognized. However, when the phase delay value of the electric active layer 122 exceeds the range of? / 4-5 nm to? / 4 + 5 nm, the light L ₅ reflected by the reflection layer 111 and passing through the electric active layer 122, May be partially visible through the linear polarizer 130 and viewed from the outside. That is, since the electroactive layer 122 functions as a phase-retarding film having a phase retardation value of? / 4, an allowable error range is? / 4-5 nm to? / 4 + 5 nm.

[Table 1] are data for determining the optimal thickness for setting the phase delay value of the uniaxially stretched PVDF film at about 4 times the elongation to about? / 4.

Incident light Phase retardation value of transmitted light by film thickness λ / 4 28μm 40μm 80μm 110μm REF 550 nm 100.83 nm 134.15 nm 290.57 nm 404.19 nm 140.15 nm 137.50 nm 560 nm 102.67 nm 136.59 nm 297.61 nm 411.54 nm 139.99 nm 140.00 nm 570 nm 103.85 nm 139.02 nm 302.92 nm 418.89 nm 140.14 nm 142.50 nm 580 nm 106.33 nm 141.46 nm 308.24 nm 426.24 nm 140.06 nm 145.00 nm 590 nm 108.17 nm 143.90 nm 313.55 nm 436.89 nm 139.46 nm 147.50 nm 600 nm 110.00 nm 146.34 nm 318.87 nm 440.94 nm 138.20 nm 150.00 nm

Referring to Table 1, when the thickness of the PVDF film is 40 μm, the phase of the incident light is delayed by about λ / 4. That is, when the thickness of the PVDF film is 40 占 퐉, the phase of the incident light is retarded to any one phase selected from the range of? / 4-5 nm to? / 4 + 5 nm. Particularly, it can be seen that the PVDF film having a thickness of 40 袖 m is uniaxially stretched at a quadruple elongation, exhibits a phase retarding effect substantially equivalent to that of a general phase retardation film (REF). Here, Cyclo Olefin Polymer (COP) film of ZEON was used as a general retardation film (REF).

As a result, in the display device 100 according to the embodiment of the present invention, in order for the electroactive layer 122 to function as a phase-retarding film, it needs to be uniaxially elongated at a specific elongation rate, and needs to have a specific thickness. For example, the electroactive layer 122 may be uniaxially stretched at an elongation of 2 to 6 times, and may have a thickness of 20 to 110 占 퐉. Preferably, when the electroactive layer 122 is made of PVDF, the electroactive layer 122 is uniaxially stretched at a fourfold elongation, and has a thickness of 40 mu m. In this case, the electric active layer 122 has a phase delay value of about? / 4 and can function as a phase retardation film for suppressing reflection of external light.

In order to suppress the reflection of external light by the phase delay effect of the electroactive layer 122, the elongation axis EA of the electroactive layer 122 is inclined at a specific angle alpha from the polarization axis PA of the linear polarizer 130 There is a need. When the angle formed by the stretching axis EA of the electroactive layer 122 and the polarization axis PA of the linearly polarizing plate 130 is 45 or 135 degrees as described above with reference to Equation 2, the sin ² (2α) of the formula 2 is one of the extraneous light reflection effect is maximized. However, in the process of forming the linear polarizer 130 and the electroactive layer 122, an angle alpha between the elongation axis EA and the polarizing axis PA may be slightly distorted. If the angle alpha between the elongating axis EA of the electroactive layer 122 and the polarization axis PA of the linearly polarizing plate 130 has an error within 45 degrees or within 2 degrees at 135 degrees, 2] sin ² (2α) is sufficiently close to the first electrically active layer 122 may suppress reflection of external light sufficiently. On the other hand, when the angle a between the elongating axis EA of the electroactive layer 122 and the polarization axis PA of the linear polarizer 130 has an error exceeding ± 2 ° at 45 ° or 135 °, 2] sin ² (2α) that may not be sufficiently close to 1, is reflected by the reflection layer 111 through the polarizing plate 130, part of the line of light (L ₅₎ passing through the electric active layer 122 outside Lt; / RTI >

As a result, the electroactive layer 122 of the display device 100 according to an embodiment of the present invention has a stretching axis EA which is inclined by about 45 DEG or about 135 DEG from the polarization axis PA of the linear polarizer 130 . Herein, about 45 ° means an angle selected from a range of 43 ° to 47 °, and about 135 ° means an angle selected from a range of 133 ° to 137 °. This reflects an angle? Between the elongation axis EA of the electro-optic layer 122 and the polarization axis PA of the linear polarizer 130, which may be generated in the process, as described above. When the elongation axis EA of the electroactive layer 122 and the polarization axis PA of the linearly polarizing plate 130 are inclined by about 45 or about 135, the light reflected by the reflective layer 111 and passing through the electroactive layer 122 (L ₅ ) can be light polarized substantially perpendicularly from the polarization axis PA of the linear polarizer 130, and the reflection of external light can be effectively suppressed.

4 is a graph showing reflectance of an electroactive layer of a display device according to an embodiment of the present invention. In order for the electro-active layer to be used as an external light reflecting film, the reflectance of the electro-active layer needs to be low. That is, when the reflectance of the electro-active layer is high, light passing through the linear polarizer can not pass through the electro-active layer and can be reflected from the surface of the electro-active layer. Therefore, the reflectance of the electroactive layer needs to be sufficiently low so that light passing through the linear polarizer can pass through the electroactive layer.

In Fig. 4, the solid line? Indicates a reflectance of a general retardation film as a comparative example. A typical phase retardation film was a Cyclo Olefin Polymer (R) film from ZEON. The thickness of a typical retardation film was 32 탆. Solid lines (1), (2) and (3) represent the reflectivities of PVDF films of 28 μm thickness, PVDF films of 80 μm thickness and PVDF film of 40 μm thickness, respectively. The PVDF film having a thickness of 28 μm, the PVDF film having a thickness of 80 μm and the PVDF film having a thickness of 40 μm were each uniaxially stretched at a stretch ratio of 4 times and the stretching axis of the PVDF film was inclined at an angle of about 45 ° from the polarizing axis of the linearly polarizing plate.

Referring to FIG. 4, as a comparative example, the reflectance of an ordinary phase retardation film is 4.76% on average.

On the other hand, the reflectance of PVDF film of 40 탆 thickness is 5.88% on average. That is, the reflectance of a PVDF film of 40 μm thickness has a difference of less than 2% from the reflectance of a typical retardation film. However, it can be seen that the reflectance difference of less than 2% is difficult to distinguish easily by the human eye, and the PVDF film of 40 탆 thickness can pass most of the light, so that it can be sufficiently used as a substitute film of the retardation film.

On the other hand, the average reflectance of the PVDF film of 80 탆 thickness is 5.96%, and the reflectance of the 28 탆 PVDF film is 5.94% on average. That is, the reflectance of a PVDF film of 80 μm thickness and the reflectance of a PVDF film of 28 μm thickness differ from each other by less than 2%. As mentioned earlier, the reflectance difference of less than 2% is difficult to distinguish easily by human eyes. However, as shown in Table 1, the PVDF film having a thickness of 28 占 퐉 and the PVDF film having a thickness of 80 占 퐉 can not retard the phase of the incident light by about? / 4. Therefore, although PVDF films of 28 탆 thick and PVDF films of 80 탆 thick have low reflectance, they are difficult to be used as phase retardation films.

As can be seen from FIG. 4, the uniaxially stretched 40 탆 PVDF film at 4 times elongation has a slightly higher reflectance than that of a general retardation film, but the phase of the incident light can be delayed to about? / 4 level. The difference in the reflectance between the PVDF film and the general retardation film is only a difficult level to be detected by the human eye, so that the suppression effect on the external light reflection can be substantially the same. Particularly, the PVDF film functions as an active layer of the contact-sensitive element, and thus has an additional function that can transmit tactile feedback to the user. Therefore, in a display device including a touch sensitive device, a general retardation film may be omitted, and a function of the phase retardation film may be substituted by a uniaxially stretched electroactive layer. Thus, the thickness of the display device can be reduced by the thickness of the omitted phase retardation film.

The display device 100 according to an exemplary embodiment of the present invention includes a touch sensitive element having an electric active layer 122 that is uniaxially stretched and can delay the phase of incident light so that it can transmit tactile feedback to a user , And a separate phase retardation film for suppressing external light reflection can be omitted. Therefore, the thickness of the display device 100 can be reduced as much as the phase retardation film is omitted. Accordingly, the display device 100 can be thinned, and the flexible display device 100 can be implemented more easily. The manufacturing cost of the display device 100 can be reduced since there is no need to separately attach the phase retardation film, which is relatively expensive, to the lower portion of the linear polarizer 130.

5 is a schematic cross-sectional view illustrating a display device according to another embodiment of the present invention. The display device 500 shown in Fig. 5 is similar to the display device shown in Figs. 1 and 2 except that the display panel 510 is an organic light emitting display panel and the touch panel 570 is disposed on the linear polarizer 130 Is substantially the same as that of the display device 100, and thus a duplicate description thereof will be omitted.

The display panel 510 is implemented as an organic light emitting display panel including an organic light emitting diode. In this case, the display panel 510 includes the organic light emitting diode composed of the anode 511, the organic light emitting layer 514 and the cathode 515, and the thin film transistor 513 configured to transmit the driving current to the organic light emitting diode. The organic light emitting diode and the thin film transistor 513 are disposed on the lower substrate 512 of the display panel 510 and the upper substrate 516 of the display panel 510 is connected to the organic light emitting diode and the thin film transistor 513, .

When the display panel 510 is a top emission type organic light emitting display panel, the light emitted from the organic light emitting diode is emitted toward the upper side of the display device 100 through the upper substrate 516. On the other hand, when the display panel 510 is the bottom emission type organic light emitting display panel, the light emitted from the organic light emitting diode is emitted in a downward direction of the display device 100 through the lower substrate 512. Fig. 5 shows an organic light emitting display panel of a top emission type as an exemplary embodiment.

The top emission type organic light emitting display panel may be configured such that the anode 511 is a reflective electrode to maximize the luminous efficiency of light generated in the organic light emitting layer 514. Light generated in the upward direction in the organic light emitting layer 514 is directly emitted toward the upper substrate 516 and light generated in the downward direction of the organic light emitting layer 514 is reflected on the anode 511, Lt; / RTI >

In this case, the anode 514 can function as a reflection layer. That is, the light incident from the outside has a specific polarization state while passing through the linear polarizer 130 and the electroactive layer 122, and is reflected by the anode 514 to have an inverted polarization state. Light reflected through the anode 514 is again blocked by the electroactive layer 122 and the linear polarizer 130, and the external light reflection can be minimized.

The touch panel 570 is disposed on the linear polarizer 130. The touch panel 570 senses a touch input to the display device 100 of the user. The touch panel 570 may be implemented by various methods such as a resistance film type, a capacitive type, an optical type, and an electromagnetic type. 5, the touch panel 570 may include a first touch electrode 571 and a first touch electrode 571 which are electrically isolated from the first touch electrode 571 and the first touch electrode 571, A second touch electrode 572 and an insulating layer 573. In this case, the touch panel 570 detects the position of the point where the touch input is applied by using the phenomenon that the capacitance of the first touch electrode 571 and the second touch electrode 572 is changed at the point where the touch input of the user is applied Can be detected.

The linear polarizer 130 disposed below the touch panel 570 has a predetermined thickness t. For example, the linear polarizer 130 has a thickness of 100 m or more. The linear polarizer 130 functions as a shielding layer so that the touch signal of the touch panel 570 is not interfered with by the electric field applied to the electric active layer 122 of the touch sensitive device 120. That is, the first touch electrode 571 or the second touch electrode 572 of the touch panel 570 can be charged due to the electric field applied to the electric active layer 122. In this case, the touch signal may be deformed or signal delay may be caused by the charged first touch electrode 571 or the second touch electrode 572. However, since the display device 500 according to another embodiment of the present invention can protect the touch panel 570 from the electric field applied to the electroactive layer 122 by the linear polarizer 130 having a thickness of 100 탆 or more, The interference phenomenon of the touch panel 570 by the touch panel 570 can be minimized.

Since the display device 500 according to another embodiment of the present invention includes the touch panel 570, it is possible to recognize the touch input and provide an intuitive touch interface to the user. In particular, the display device 500 according to another embodiment of the present invention includes a linear polarizer 130 disposed between the touch panel 570 and the touch sensitive device 120, and the linear polarizer 130 is a shield layer It is not necessary to dispose a separate shielding layer. Therefore, the thickness increase of the display device 500 due to the separate shielding layer can be minimized, and the implementation of the thin display device 500 can be made easier.

According to some embodiments, the touch panel 570 may further include a pressure sensor. The pressure sensor can measure the intensity of the touch input. For example, the thickness of the insulating layer 573 may be locally reduced at a point where the touch input of the user is applied, and the thickness of the insulating layer 573 may be changed, And the second touch electrode 572 may be changed. The pressure sensor can measure the intensity of the touch input by detecting such a capacitance change. In this case, since the touch panel 570 can measure not only the two-dimensional position of the touch input but also the intensity of the touch input, the display device 500 can receive various touch inputs, So that various tactile feedback can be provided according to the strength of the touch input.

Figure 6 is an illustration of examples in which a display device according to various embodiments of the present invention may be advantageously utilized. 6 (a) shows a case where a display device 610 according to an embodiment of the present invention is used in the mobile device 600. In FIG. A display device 610 according to an embodiment of the present invention is shown included in the mobile device 600 in Figure 5a where the mobile device 600 may be a smartphone, a cell phone, a tablet PC, a PDA, etc. Means a miniaturization device. When the display device 610 is installed in the mobile device 600, the user can perform various functions of the mobile device 600 by applying a touch input directly to the screen of the display device 610. [

In particular, since the display device 610 according to one embodiment of the present invention includes a thin film-type touch sensitive device, the mobile device 600 can provide various tactile feedback in response to a user's touch input. For example, when a user watches a video, inputs a game, or inputs a button to the mobile device 600, the user can feel vibration with the touch, and more sensible information can be received. Also, as the thickness of the display device 610 becomes thinner, the thinness and lightness of the mobile device 600 can be facilitated and the implementation of the flexible mobile device 600 can be facilitated.

6 (b) shows a case where the display device according to the embodiment of the present invention is used in the navigation system 700 for a vehicle. The in-vehicle navigation 700 may include a display device 710 and a plurality of operating elements, and may be controlled by a processor installed inside the vehicle. When the display device 710 is applied to the navigation system 700 for a vehicle, it is possible to tactilely provide the height of the road, the state of the road, and the progress of the vehicle, so that the operation of the driver's navigation system 700 Can be made easier.

FIG. 6C shows a case where the display device according to one embodiment of the present invention is used as a display means 800 such as a monitor, a TV, or the like. When the display device 810 according to an embodiment of the present invention is used as the display means 800, the user applies a touch input directly to the screen of the display device 810 to perform various functions of the display means 800 And feel the tactile sensation of the object displayed on the display means 800 based on the tactile feedback provided by the display means 800. [ Accordingly, the user can enjoy a more realistic image, and the visually impaired can appreciate various contents through the tactile experience. Particularly, since the touch sensitive element of the display device 810 according to the embodiment of the present invention has a function of suppressing reflection of external light, even when viewing the display means 800 in a bright place, the visibility of the display means 800 Can be minimized.

FIG. 6 (d) shows a case where a display device according to an embodiment of the present invention is used in an outdoor billboard 900. The outdoor billboard 900 may include a display device 910 and a support for connecting the display device 910 to the ground. When the display device 910 according to an embodiment of the present invention is applied to the outdoor billboard 900, information on the advertisement product to be sold can be transmitted through the haptic medium beyond the visual and auditory media have. Accordingly, the user can receive the tactile information on the advertisement item by touching the outdoor billboard 900, and the advertisement effect can be maximized. In particular, since the touch sensitive element of the display device 910 has a function of suppressing reflection of external light, the visibility of the outdoor billboard 900 can be further improved.

FIG. 6E shows a case where a display device according to various embodiments of the present invention is used in the game device 1000. FIG. The game device 1000 may include a display device 1010, and a housing in which various processors are embedded. When the display device 1010 according to an embodiment of the present invention is applied to the game device 1000, the user can operate the game by directly touching the screen of the display device 1010, Various tactile feedbacks according to the game operation of the user are realistically provided, so that the user's immersion into the game can be doubled. In particular, since the touch sensitive element of the display apparatus 1010 has a function of suppressing the reflection of external light, the user has an advantage that the user can view the screen of the game apparatus 1000 outdoors without inconvenience.

6 (f) shows a case where a display device according to an embodiment of the present invention is used in the copyboard 1100. The copyboard 1100 may include a display device 1110, a speaker, and a structure for protecting them from an external impact. When the display device 1110 according to an embodiment of the present invention is applied to the electronic blackboard 1100, when the contents of a lecture are input to the display device 1110 with a stylus pen or a finger, . ≪ / RTI > In addition, when the trainee applies the touch input to the image displayed on the electronic whiteboard 1100, the tactile feedback suitable for the image can be provided to the trainee, so that the effect of the training can be maximized.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, which is capable of reading information from, and writing information to, the storage medium. Alternatively, the storage medium may be integral with the processor. The processor and the storage medium may reside within an application specific integrated circuit (ASIC). The ASIC may reside within the user terminal. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

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. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. 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, 500, 610, 710, 810, 910, 1010, 1110:
110, 510: display panel
111: reflective layer
120: contact sensitive element
121: first electrode
122: electric active layer
123: second electrode
130: linear polarizer
140: Cover window
511: anode
512: Lower substrate
513: Thin film transistor
514: Organic light emitting layer
515: cathode
516: upper substrate
571: first touch electrode
572: second touch electrode
573: Insulation layer
d: thickness of the electroactive layer
t: thickness of linear polarizer
α: Angle of polarization axis and extension axis

Claims (12)

Display panel;
A touch sensitive element on the display panel; And
And a linear polarizer on said contact sensitive element,
Wherein the touch sensitive element includes an electrically active layer that is uniaxially stretched and configured to delay the phase of the incident light. The method according to claim 1,
The electroactive layer is configured to delay the phase of incident light by about? / 4, and? Is a wavelength of the incident light. The method according to claim 1,
Wherein the electroactive layer is made of a PVDF (polyvinylidene fluoride) -based polymer. The method of claim 3,
The electroactive layer is a uniaxially stretched film,
And the thickness of the electroactive layer is 40 占 퐉. The method according to claim 1,
Wherein the display panel is an organic light emitting display panel including a reflective layer. 6. The method of claim 5,
Wherein the reflective layer comprises at least one of an anode, a cathode, a metal wiring, a surface of a color filter, and a surface of a black matrix. The method according to claim 1,
Wherein the contact sensitive element further comprises an electrode disposed on at least one surface of the electroactive layer. Display panel;
A linear polarizer on the display panel; And
And a contact sensitive element disposed between the display panel and the linear polarizer and having a stretching axis inclined at a predetermined angle from a polarization axis of the polarizer. 9. The method of claim 8,
Wherein the contact sensitive element comprises an electroactive layer and an electrode disposed on at least one side of the electroactive layer,
Wherein the stretching axis of the contact sensitive element is a stretching axis of the electroactive layer which is inclined by 43 ° to 47 ° or 133 ° to 137 ° from the polarizing axis of the polarizing plate. 10. The method of claim 9,
Wherein the electroactive layer is a uniaxially stretched film. 10. The method of claim 9,
Wherein the thickness d of the electroactive layer and the effective refractive index DELTA _neff of the electroactive layer satisfy the following equation.
[Equation 1]

9. The method of claim 8,
And a touch panel disposed on the linear polarizer,
And the thickness of the linear polarizer is 100 m or more.

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