KR20150136651A - See through display apparatus - Google Patents

Abstract

The present invention provides a transmission type display apparatus. The transmission type display apparatus comprises a display unit made of a cholesteric liquid crystal of which a state structure is changed by pressure or heat applied from the outside. Therefore, the transmission type display apparatus can maintain a transmission state by transmitting the light from the outside or display colors by scattering or reflecting the light from the outside.

Description

[0001] SEE THROUGH DISPLAY APPARATUS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a transmissive display device, and more particularly, to a transmissive display device capable of reflecting external light or displaying colors using a cholesteric liquid crystal.

The liquid crystal used in the conventional liquid crystal display device includes a twisted nematic liquid crystal, a semetic liquid crystal, and a cholesteric liquid crystal.

Double cholesteric liquid crystals have been used in reflective display devices. More specifically, the cholesteric liquid crystal changes into three states consisting of two stable states, a planar state, a focal conic state, and a homeotropic state other than the planar state and the focal conic state. .

In addition, the cholesteric liquid crystal can selectively reflect the light with respect to the external light, and in particular, the focal conic phase that scatters external light during the state transition of the cholesteric liquid crystal, and the planar image that reflects external light, Display devices.

Particularly, in a conventional cholesteric liquid crystal, when the state changes to a focal conic state on the planar or a state changes to a planar state on a focal conic state, a voltage is applied to the cholesteric liquid crystal, After going through the tropic phase, it has turned into another phase.

As mentioned above, since the focal conic phase of the cholesteric liquid crystal scatters the external light and the planar image reflects the external light, the focal conic phase and the planar phase do not transmit external light, while the homeotropic phase has external There is a characteristic of transmitting light.

As a result, the conventional reflective display device using a cholesteric liquid crystal has a problem in that it can not maintain a homeotropic phase capable of transmitting external light in a state in which no voltage is applied.

Therefore, in order to keep the display device in a transparent state, the phase should be changed to a homeotropic phase, which is a state structure capable of transmitting external light, and the voltage should be continuously applied to the cholesteric liquid crystal.

As a result, the power consumption of the display device increases.

1. Reflection type liquid crystal display and control method thereof (Patent Application No. 10-2011-0103726)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device using a cholesteric liquid crystal, And to provide a display device.

Another object of the present invention is to provide a liquid crystal display device capable of displaying a color by scattering or reflecting external light as an image of a cholesteric liquid crystal is changed by external pressure or heat in a transparent state at the initial stage of driving without applying a voltage, A transparent window, a transparent window, a smart window, a transparent electronic board, or a transparent electronic note.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters 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 transmissive display device including a first substrate and a second substrate facing each other, an electrode portion formed on the first substrate and the second substrate, 2 substrate, and the liquid crystal unit is formed of a cholesteric liquid crystal having a homeotropic state for transmitting external light without applying a voltage.

In addition, when pressure is applied to the liquid portion, the pressure-applied cholesteric liquid crystal region may be changed into a focal conic state or a planar state.

Also, when heat is applied to the liquid crystal, the cholesteric liquid crystal region to which heat is applied may be changed into a focal conic state or a planar state.

In addition, the region changed into the focal-conic state can display white color by scattering external light.

In addition, the region changed into the planar surface can display the color of the wavelength reflected according to the pitch of the cholesteric liquid crystal.

When the voltage difference is formed in the electrode portion, the phase-changed region may be changed into a homeotropic phase.

At least one of the electrode portions formed on the first substrate or the electrode portions formed on the second substrate may be a patterned electrode.

Further, when an electric field is formed in the cholesteric liquid crystal, the cholesteric liquid crystal may change from a homeotropic state to a focal conic phase or a planar phase.

Further, the transmissive display device may further include an alignment portion formed in the electrode portion, and the alignment portion may arrange the cholesteric liquid crystal in a homeotropic manner.

The transmissive display device may further include an alignment material which is mixed with the cholesteric liquid crystal and arranges the phase of the cholesteric liquid crystal in a homeotropic phase.

The liquid crystal unit may be formed by mixing cholesteric liquid crystals having different pitches.

According to another aspect of the present invention, there is provided a transmissive display device including a plurality of display portions made of cholesteric liquid crystal, wherein the cholesteric liquid crystal has a homeotropic phase which transmits external light without applying a voltage, .

The pitches of the cholesteric liquid crystals constituting the plurality of display portions may be different or the same.

The plurality of display units may display different series of colors or may display the same series of colors.

The display unit includes a first substrate and a second substrate facing each other, and an electrode unit formed on the first substrate and the second substrate. The cholesteric liquid crystal is formed between the first substrate and the second substrate .

There is an effect of providing a cholesteric liquid crystal having a homeotropic phase capable of transmitting external light without applying a voltage according to an embodiment of the present invention.

Accordingly, it is possible to provide a transmissive display device in which a basic state in a general environment is always maintained in a transparent state without applying a voltage.

Further, since the transparent state can be maintained without applying a voltage, the power consumption can be reduced.

As the image of the cholesteric liquid crystal is changed by external pressure or heat, the external light is scattered or reflected to display the color.

Thereby, it is possible to provide a transmissive display device which can be applied to a smart window, a transparent electronic whiteboard, a transparent electronic note, or the like.

1 is a cross-sectional view of a transmissive display device according to an embodiment of the present invention;
2 is a cross-sectional view of a transmissive display device showing an initial transparent state in a homeotropic state;
3A to 3D are sectional views showing various embodiments of the electrode portion.
4 is a conceptual view showing a wavelength band reflected according to a pitch and a pitch of a cholesteric liquid crystal.
FIG. 5 is a cross-sectional view of a transmissive display device in which external light is changed to a focal conic state to scatter external light. FIG.
6 is a cross-sectional view of a transmissive display device showing a state of displaying a color as external light is reflected by a planar state under external pressure.
7 is a cross-sectional view of a transmissive display device that receives heat from the outside and changes state to a focal conic state to scatter external light.
8 is a cross-sectional view of a transmissive display device showing a state in which colors are displayed by receiving heat from the outside and changing into a planar state and reflecting external light.
9 is a sectional view of a transmissive display device according to another embodiment of the present invention.
10 is a sectional view of a transmissive display device according to another 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 concept of the invention to those skilled in the art. To fully disclose the scope of the invention to a person 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," "consisting of," and the like are used in this specification, other portions may be added as long as "only" is not 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.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

The first, second, etc. are used to describe various components, but 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.

The terms "X-axis direction "," Y-axis direction ", and "Z-axis direction" should not be construed solely by the geometric relationship in which the relationship between them is vertical, It may mean having directionality.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, May refer to any combination of items that may be presented from more than one.

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.

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

FIG. 1 is a cross-sectional view of a transmissive display device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a transmissive display device showing an initial transparent state in a homeotropic state.

The transmissive display device 100 according to an embodiment of the present invention includes a first substrate 110 and a second substrate 120 facing each other, an electrode unit 130, a liquid crystal unit 140, and an alignment unit 150, and the liquid crystal unit 140 includes a cholesteric liquid crystal.

Referring to FIG. 2, when a UV (ultraviolet) curing process is performed between the first substrate 110 and the second substrate 120 after the injection, the cholesteric liquid crystal is aligned by the alignment unit 150 comprising a vertical alignment film And may have a homeotropic state.

Thus, the cholesteric liquid crystal constituting the liquid crystal unit 140 maintains a homeotropic phase that transmits external light without a voltage applied from the outside.

In other words, even if an electric field is not formed in the cholesteric liquid crystal, the cholesteric liquid crystal constituting the liquid crystal unit 140 can always maintain the homeotropic phase in the initial state by the aforementioned manufacturing process.

Therefore, the initial state of the liquid crystal 140 according to the embodiment of the present invention is a transparent state in which external light is transmitted.

The first substrate 110 and the second substrate 120 may be used for a general display device or a substrate used for manufacturing a flexible display device.

More specifically, the material used for the first substrate 110 and the second substrate 120 may be a transparent glass-based material or a transparent plastic-based material.

For example, a cellulose resin such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose), a cyclic olefin polymer (COP) such as a norbornene derivative, a cyclic olefin copolymer (COC), an acrylic resin such as poly (methylmethacrylate) Polyether sulfone (PES), polyetheretherketone (PEEK), polyetherimide (PEI), polyethylenenaphthalate (PEN), polyethyleneterephthalate (PET), polyolefin such as polycarbonate, PC (polyethylene) (Polyimide), polysulfone (PSF), or a fluororesin or the like may be used, but the present invention is not limited thereto.

The electrode unit 130 may include a first electrode 131 formed on the first substrate 110 and a second electrode 132 formed on the second substrate 120.

More specifically, the electrode unit 130 may be made of a transparent conductive material having conductivity and capable of transmitting external light.

For example, the transparent conductive material may be a silver oxide (e.g., AgO), an aluminum oxide (e.g. Al2O3), a tungsten oxide (e.g. WO2 or WO3), a magnesium oxide (e.g. MgO), a molybdenum oxide (e.g. MoO3) (Eg ZnO), tin oxide (eg SnO2), indium oxide (eg In2O3), chromium oxide (eg CrO3 or Cr2O3), antimony oxide (eg Sb2O3 or Sb2O5), titanium oxide (eg TiO2) , Nickel oxides such as NiO, copper oxides such as CuO or Cu2O, vanadium oxides such as V2O3 or V2O5, cobalt oxides such as CoO, iron oxides such as Fe2O3 or Fe3O4, (Eg, Nb2O5), indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (ZAO), aluminum-doped zinc oxide ; AZO), antimony tin oxide (e.g., ATO), and the like. The only are not limited.

Accordingly, the first electrode 131 and the second electrode 132, which are externally applied with a voltage, can generate an electric field that can change the phase arrangement of the cholesteric liquid crystal constituting the liquid crystal 140.

3A to 3D, which are cross-sectional views illustrating various embodiments of the electrode unit according to the embodiment of the present invention, any one of the first electrode 131 and the second electrode 132 may be a pattern electrode .

When a voltage is applied to the first electrode 131 or the second electrode 132, which may be a patterned electrode, to generate an electric field, the cholesteric liquid crystal constituting the liquid crystal unit 140 may have a focal conic phase Or on a planner.

For example, as shown in FIG. 3A, the first electrode 131a formed on the first substrate 110 may be a patterned electrode, and may be formed on the second substrate 120 as shown in FIG. The second electrode 132b may be a pattern electrode.

As shown in FIG. 3C, the first electrode 131c formed on the first substrate 110 and the second electrode 132c formed on the second substrate 120 may be patterned electrodes, respectively.

When the first electrode 131c and the second electrode 132c are both patterned electrodes as shown in FIG. 3C, an electric field capable of phase-changing the cholesteric liquid crystal in both directions is generated. As shown in FIG. 3B, when a pattern electrode is formed on only one side, even if a smaller voltage is applied, the pattern can easily be changed to a focal conic phase or a planar phase on the homeotropic pattern.

Accordingly, when both the first electrode 131 and the second electrode 132 are formed as pattern electrodes, it can be driven at a low voltage, the phase change can be more easily performed, and the phase change time can be shortened.

The first electrode 131d is formed on the entire surface of the first substrate 110 and a negative voltage is applied to the lower portion of the second substrate 120 facing the first substrate 110 as shown in FIG. A common electrode 133d may be formed on the first substrate 120 and a second electrode 132d may be formed on the second substrate 120 by applying a positive voltage.

At this time, the common electrode 133d is formed on the third substrate 121 and disposed between the second substrate 120 and the third substrate 121.

The first electrode 131 and the second electrode 132 may be formed as pattern electrodes to change the entire cholesteric liquid crystal to a focal-conic or planar image, or alternatively, to selectively cover only a part of the cholesteric liquid crystal, Conical phase or planar phase.

Accordingly, the entire area of the transmissive display device 100 may display a white color by scattering external light, or only a part of the area may scatter external light to display a white color have.

In addition, the entire area of the transmissive display device 100 may reflect external light to display a color, or only a part of the area may reflect external light to display a color.

According to an embodiment of the present invention, the liquid crystal 140 is formed between the first substrate 110 and the second substrate 120 and is formed of a cholesteric liquid crystal.

Cholesteric liquid crystals can also be formed by adding a chiral dopant or a photo-sensitive chiral dopant to the nematic liquid crystal to induce a periodic helix structure, Additives such as photoinitiators may be further included.

The homeotropic state referred to in the embodiment of the present invention means a state in which the cholesteric liquid crystal is arranged in a direction perpendicular to the electrode unit 130 or the first and second substrates 110 and 120 do.

The focal conic state refers to a state in which the helical axis of the cholesteric liquid crystal is randomly arranged with respect to the electrode unit 130 or the first and second substrates 110 and 120.

And a planar state refers to a state in which the helix axis of the cholesteric liquid crystal is arranged in the direction perpendicular to the electrode unit 130 or the first and second substrates 110 and 120.

Particularly, the cholesteric liquid crystal constituting the liquid crystal part 140 according to the embodiment of the present invention can maintain the homeotropic phase even when no electric field is applied.

More specifically, the cholesteric liquid crystal is injected between the first substrate 110 and the second substrate 120 and is irradiated onto the alignment part 150 or the alignment material 250, which is a vertical alignment film to be described later, The cholesteric liquid crystal constituting the liquid crystal 140 can always maintain the homeotropic phase even without an electric field.

The liquid crystal unit 140 of the transmissive display device 100 in a normal state in which no voltage is applied to the first electrode 131 and the second electrode 132 or no pressure or heat is applied to the liquid crystal unit 140, The transmissive display device 100 can be applied to a smart window, a transparent electronic blackboard, a transparent electronic notebook, or the like using a transmissive window because external light is transmitted and maintained in a transparent state.

In addition, according to the pitch of the cholesteric liquid crystal, a specific wavelength band of external light can be selectively reflected to display a color.

The wavelength of the reflected external light is expressed by the product of the average refractive index of the liquid crystal and the pitch of the cholesteric liquid crystal.

Therefore, by adjusting the pitch of the cholesteric liquid crystals, it is possible to control the reflection color variously.

In order to variously form the pitch of the cholesteric liquid crystal, a method of controlling the pitch of the liquid crystal by controlling the light amount of the UV light irradiating the cholesteric liquid crystal or controlling the temperature of the cholesteric liquid crystal, A method of controlling the pitch or a method of controlling the pitch of the liquid crystal by controlling the concentration of the chiral dopant can be used.

That is, when the cholesteric liquid crystal is cured by using the UV exposure, the pitch of the cholesteric liquid crystal can be controlled by a difference in exposure intensity (difference in light amount), a difference in exposure temperature, a difference in polymerization rate, and the like.

Therefore, in explaining the embodiment of the present invention, a detailed description of the manufacturing process for curing the cholesteric liquid crystal will be omitted.

Referring to FIG. 4, which is a conceptual diagram illustrating the wavelength band reflected by the pitch and pitch of the cholesteric liquid crystal, the color of the red color of the long wavelength region band is reflected as the pitch of the cholesteric liquid crystal becomes longer And as the pitch of the cholesteric liquid crystal becomes shorter, the blue color of the color of the short wavelength band can be reflected and displayed.

That is, the longer the pitch of the cholesteric liquid crystals is, the more the color of the red series which is the near wavelength band of 760 nm in the visible light can be reflected.

Further, as the pitch of the cholesteric liquid crystal is short, the blue color of the near-wavelength band of 380 nm in the visible light can be reflected.

By adjusting the pitch of the cholesteric liquid crystal, it is possible to reflect the color of the green series near the wavelength of 550 nm in visible light.

Accordingly, various colors can be displayed by variously controlling the pitch of the cholesteric liquid crystal constituting the liquid crystal part 140. [

For example, when the pitches of the cholesteric liquid crystals are all made the same, the liquid crystal unit 140 can display only the color of the wavelength band corresponding to the liquid crystal pitch.

In addition, when the liquid crystal part 140 is formed by mixing cholesteric liquid crystals having different pitch values, the liquid crystal part 140 may display a mixed color of a red-based color and a blue-based color, or may display a red- You can display a mixed color of green-based colors, a mixed color of green-based colors and blue-based colors, or a mixture of red-based colors, green-based colors, and blue-based colors have.

The alignment unit 150 is for vertically aligning the cholesteric liquid crystal to be UV cured and includes a first alignment layer 151 formed on the first electrode 131 and a second alignment layer 152 formed on the second electrode 132 ).

Also, the alignment unit 150 according to an embodiment of the present invention may be formed of any one of polyimide series and phosphatidylcholine (PPC) series, and the cholesteric liquid crystal may be arranged vertically.

In addition, the alignment unit 150 may be formed by mixing hexadecyltrimethylammonium bromide (HTAB) or cetyl trimethyl ammonium bromide (CTAB) as a vertical alignment material in a solvent such as isopropyl alcohol (IPA) And then evaporating the solvent after coating the two electrodes 132.

The transmissive display device 100 may further include a spacer 160 to maintain a space between the first substrate 110 and the second substrate 120.

The spacers 160 may serve as barrier ribs for separating the space from the space and through which the cholesteric liquid crystals with different pitches can be injected.

The transmissive display device 100 according to the embodiment of the present invention scatters external light through a phase change of the cholesteric liquid crystal constituting the liquid crystal part 140 to display a white color or reflect external light, Can be displayed.

5, which is a cross-sectional view of a transmissive display device showing a state of receiving external pressure and changing into a focal conic state and scattering external light, is applied to the liquid crystal part 140 of the transmissive display device 100 When pressure (P) acts, the pressure-applied cholesteric liquid crystal region (a1) may change from a homeotropic state to a focal conic state.

As a result, the region a1 of the cholesteric liquid crystal changed into the focal-conic state displays white color (W) by scattering external light.

When a potential difference is formed between the first electrode 131 and the second electrode 132 constituting the electrode unit 130 to form an electric field in the cholesteric liquid crystal, the spiral structure of the cholesteric liquid crystal having the focal conic phase And becomes a homeotropic phase.

Based on this, texts and the like can be displayed on a smart window, a transparent electronic board, or a transparent electronic note.

In addition, when a light shielding plate using electrochromic (EC) or polymer dispersed liquid crystal (PDLC) is coupled to the back surface of the transmissive display device 100, the light shielding plate is shielded from external light while displaying black, 100), it is possible to provide a high visibility to the user when the text is displayed in white color.

6, which is a cross-sectional view of the transmissive display device showing a state of displaying a color according to external light while being reflected by the planar state by receiving external pressure and reflecting external light, the liquid crystal part 140 of the transmissive display device 100, The cholesteric liquid crystal may change from a homeotropic liquid to a planar state when a pressure higher than a pressure for changing the phase of the cholesteric liquid crystal from the homeotropic state to the focal conic state is applied to the cholesteric liquid crystal.

In this process, the cholesteric liquid crystals change from a homeotropic phase to a focal conic phase and then to a frac- tional phase, although at a very short time.

Thus, the region a2 turned into a planar image can display the color by reflecting the wavelength band of the external light corresponding to the pitch of the cholesteric liquid crystal.

That is, the area a2 changed to the planar can display red-based color, green-based color, or blue-based color, or display mixed colors thereof.

When a potential difference is formed between the first electrode 131 and the second electrode 132 constituting the electrode unit 130 to form an electric field in the cholesteric liquid crystal, the planar image is changed into a homeotropic phase, Is again in a transparent state.

Based on this, it is possible to display text having colors such as a smart window, a transparent electronic blackboard, or a transparent electronic note.

In addition, when a light shielding plate using electrochromic (EC) or polymer dispersed liquid crystal (PDLC) is coupled to the back surface of the transmissive display device 100, the light shielding plate is shielded from external light while displaying black, 100), it is possible to provide a high visibility to a user when displaying text in a color other than black.

FIG. 7 is a cross-sectional view of a transmissive display device that receives heat from the outside and changes state to a focal conic state to scatter external light. FIG. 8 shows a planar state by receiving heat from the outside Sectional view of a transmissive display device showing a state in which colors are displayed upon reflection of external light.

Referring to FIGS. 5 and 6, when heat (heat) H is applied to the liquid crystal unit 140 similarly to the case where pressure is applied to the liquid crystal unit 140 of the transmissive display device 100, 140 may be changed into a focal conic state or a planar state.

More specifically, when a heat source having a temperature of 30 占 폚 or more is applied to the liquid portion 140, the region a3 to which the heat H is applied may change to a focal conic state.

Thus, the area a3 changed into the focal-conic shape displays light of a white color (W) by scattering external light.

When a potential difference is formed between the first electrode 131 and the second electrode 132 constituting the electrode unit 130 to form an electric field in the cholesteric liquid crystal, the spiral structure of the cholesteric liquid crystal having the focal conic phase And becomes a homeotropic phase.

Based on this, texts and the like can be displayed on a smart window, a transparent electronic board, or a transparent electronic note.

In addition, when a light shielding plate using electrochromic (EC) or polymer dispersed liquid crystal (PDLC) is coupled to the back surface of the transmissive display device 100, the light shielding plate is shielded from external light while displaying black, 100), it is possible to provide a high visibility to the user when the text is displayed in white color.

Referring to FIG. 8, when a temperature higher than a temperature for changing the phase of the cholesteric liquid crystal from the homeotropic phase to the focal conic phase is applied to the liquid crystal 140 of the transmissive display device 100, Region a4 may change from an initial phase homeotropic to a planar state.

For example, when a heat source having a temperature of 38 DEG C or higher is applied to the liquid level portion 140, the cholesteric liquid crystal may change from homeotropic to flaser.

In this process, the cholesteric liquid crystals change from a homeotropic phase to a focal conic phase and then to a frac- tional phase, although at a very short time.

Thus, the area a4 turned into a planar image can display the color by reflecting the wavelength range of the external light corresponding to the pitch of the cholesteric liquid crystal.

That is, the area (a4) changed to the planar surface can display a red-based color, a green-based color, a blue-based color, or a mixed color thereof.

When a voltage is applied to the electrode unit 130 to form an electric field in the cholesteric liquid crystal, the phase of the cholesteric liquid crystal on the planar surface is changed into a homeotropic phase, and the liquid crystal unit 140 is kept in a transparent state .

Based on this, it is possible to display text having colors such as a smart window, a transparent electronic blackboard, or a transparent electronic note.

In addition, when a light shielding plate using electrochromic (EC) or polymer dispersed liquid crystal (PDLC) is coupled to the back surface of the transmissive display device 100, the light shielding plate is shielded from external light while displaying black, 100), it is possible to provide a high visibility to a user when displaying text in a color other than black.

In addition, the phase of the cholesteric liquid crystal constituting the transmissive display device 100 can be changed by simultaneously using pressure and heat.

That is, when pressure and heat are simultaneously applied to the cholesteric liquid crystal, it is possible to shorten the time from the homeotropic to the focal-conic phase or from the homeotropic phase to the planar phase, which is the initial phase of the cholesteric liquid crystal.

5 to 8, the input device capable of applying pressure or heat to the transmissive display device according to the embodiment of the present invention can be a human body or a pen-shaped input tool.

That is, when a finger of a human being is used, a method of applying pressure to the liquid portion 140 with the tip of the finger can be used.

And a heat input method and a pressure input method can be used for the liquid portion 140 through the body heat and the pressure generated from a finger or other human body part.

In addition, a method of applying a pressure to the liquid level portion 140 using a pen having a pen shape and a round shape having a predetermined curvature may be used.

In addition, it is possible to use both the pressure input method and the heat input method by using a pen having a hollow shape and a hollow hole formed therein to allow a light source such as an LED to generate heat.

9 is a cross-sectional view of a transmissive display device according to another embodiment of the present invention. In describing the present embodiment, description of the same or corresponding elements to those of the previous embodiment will be omitted. Hereinafter, the transmissive display device according to the present embodiment will be described with reference to the drawings.

9, a transmissive display device 200 according to another embodiment of the present invention includes a first substrate 210 and a second substrate 220 facing each other, an electrode portion 230, a liquid portion 240, And the liquid crystal unit 240 includes a cholesteric liquid crystal.

The first substrate 210, the second substrate 220 and the electrode unit 230 are the same as the first substrate 110, the second substrate 120, and the electrode unit 130 described above with reference to FIG. do.

The liquid crystal 240 according to the present embodiment may be formed by mixing a cholesteric liquid crystal and an alignment material 250 capable of maintaining a cholesteric liquid crystal on homeotropic phase after UV curing.

More specifically, the alignment material 250 is a material that vertically arranges the cholesteric liquid crystals with respect to the first substrate 210 and the second substrate 220, such as hexadecyltrimethylammonium bromide (HTAB), cetyl trimethyl ammonium bromide (CTAB) a polyhedral oligomeric silsesquioxane, a dendronized polymer, a dendrimer, or a mixture thereof. However, the present invention is not limited thereto.

The transmissive display device 200 may further include a spacer 260 to maintain a space between the first substrate 210 and the second substrate 220.

The spacers 260 may function as barrier ribs for separating the spaces from each other. The spacers 260 may inject cholesteric liquid crystals having different pitches of liquid crystal in the respective spaces.

10 is a cross-sectional view of a transmissive display device according to another embodiment of the present invention. In describing the present embodiment, description of the same or corresponding elements to those of the previous embodiment will be omitted. Hereinafter, the transmissive display device according to the present embodiment will be described with reference to the drawings.

10, the transmissive display device 300 according to another embodiment of the present invention may be composed of a plurality of display portions made of cholesteric liquid crystal, and the cholesteric liquid crystal constituting each display portion may be a display device And may have a homeotropic phase that transmits external light.

For example, when the transmissive display device 300 includes three display units 340a, 340b, and 340c as shown in FIG. 10, the display units 340a, 340b, and 340c may include a first substrate 310 and a second substrate 370b and 370c includes a first substrate 310 and a second substrate 320. The second substrate 320 includes a first substrate 310 and an electrode unit 330 formed on the first substrate 310 and the second substrate 330. The cholesteric liquid crystals 370a, 320).

Each of the display units 340a, 340b, and 340c may selectively include any one of an alignment unit formed between the first substrate 310 and the second substrate 320 or an alignment material that can be mixed with the cholesteric liquid crystal Which is the same as the orientation unit 150 comprising the vertical alignment film described above with reference to FIG. 2 and the orientation material 250 described with reference to FIG.

10, a transmissive display device 300 including an alignment part 330 formed between a first substrate 310 and a second substrate 320 is shown.

Similar to the cholesteric liquid crystals 140 and 240 described above with reference to FIGS. 2 and 9, the cholesteric liquid crystals 370a, 370b, and 370c according to the present embodiment can be formed as homeotropic liquid crystals it is possible to maintain a homeotropic state.

Therefore, the initial state of each of the display portions 340a, 340b, and 340c of the transmissive display device 300 according to the present embodiment is a transparent state in which external light is transmitted without applying a voltage.

In this embodiment, the pitches of the cholesteric liquid crystals 370a, 370b and 370c are different from each other in each of the display units 340a, 340b and 340c in order to display different colors in the plurality of display units 340a, 340b and 340c can do.

In addition, the pitch of the cholesteric liquid crystals can be selectively equalized to display the same color in some selected display portions.

The pitch of the cholesteric liquid crystal 370a of the first display portion 340a is equal to the pitch of the cholesteric liquid crystal 370b of the second display portion 340b and the pitch of the cholesteric liquid crystal 370b of the third display portion 340c according to the embodiment of the present invention. And may be different from or equal to the pitch of the steric liquid crystal 370c.

The pitch of the cholesteric liquid crystal 370a of the first display portion 340a is set to be larger than the pitch of the cholesteric liquid crystal 370b of the second display portion 340b and the pitch of the cholesteric liquid crystal 370b of the second display portion 340b is larger than that of the cholesteric liquid crystal 370b of the second display portion 340b, The pitch of the liquid crystal 370b may be smaller than the pitch of the cholesteric liquid crystal 370c of the third display portion 340c and the pitch of the first display portion 340a may be larger than the pitch of the third display portion 340c.

Accordingly, when pressure or heat is applied from the outside, the first display portion 340a can display a red-based color, the second display portion 340b can display a blue-based color, 3 display unit 340c can display a green-based color.

As another example, when the pitch of the cholesteric liquid crystal 370a of the first display portion 340a is made equal to the pitch of the cholesteric liquid crystal 370b of the second display portion 340b and the pitch of the cholesteric liquid crystal 370b of the third display portion 340c The first display unit 340a and the second display unit 340b display the same color while the third display unit 340c displays the same color when the first display unit 340a and the second display unit 340b are different from the pitch of the liquid crystal 370c. A different color can be displayed.

In addition, if the pitches in the cholesteric liquid crystal 370a of the first display portion 340a are different from each other, a color in which a red-based color and a blue-based color are mixed or a red-based color and a green- A mixed color of a blue-based color and a green-based color, and a mixed color of a red-based color, a green-based color, and a blue-based color can be displayed in various ways.

In the above-described mixing of colors, the first display portion 340a has been described as an example. However, when the pitches in the cholesteric liquid crystal are different from each other in the display portions other than the first display portion 340a, various colors can be displayed.

Based on this, when the transmissive display device 300 according to the present embodiment is applied to a smart window, a transparent electronic blackboard, a transparent electronic note, or the like, text and the like can be displayed in various colors.

In addition, when a light shielding plate using electrochromic (EC) or polymer dispersed liquid crystal (PDLC) is coupled to the back surface of the transmissive display device 300, the light shielding plate is shielded from external light while displaying black, 300 can provide high visibility to the user when displaying text having color.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the present invention is not to be limited to the details of the foregoing disclosure, It will be apparent that modifications and improvements can be made by those skilled in the art.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: transmissive display device 110: first substrate
120: second substrate 130: electrode part
140: Liquid supply unit 150:
160: Spacer

Claims (15)

A first substrate and a second substrate facing each other;
An electrode unit formed on the first substrate and the second substrate; And
And a liquid crystal portion formed between the first substrate and the second substrate,
Wherein the liquid crystal unit comprises a cholesteric liquid crystal having a homeotropic state for transmitting external light without applying a voltage.
The method according to claim 1,
Wherein the pressure-applied cholesteric liquid crystal region is changed into a focal conic state or a planar state when a pressure is applied to the liquid portion.
The method according to claim 1,
Wherein when the liquid is heated, the cholesteric liquid crystal region where heat is applied is changed into a focal conic state or a planar state. The method according to claim 2 or 3,
The region, which has changed into a focal conic state,
A light-scattering display device which displays white color by scattering external light.
The method according to claim 2 or 3,
The area turned into a planar
And a color of a wavelength reflected according to a pitch of the cholesteric liquid crystal.
The method according to claim 2 or 3,
Wherein when the voltage difference is formed in the electrode portion, the phase-changed region changes to a homeotropic phase.
The method according to claim 1,
Wherein at least one of the electrode portions formed on the first substrate or the electrode portions formed on the second substrate is a patterned electrode.
The method of claim 7,
Wherein when the electric field is formed in the cholesteric liquid crystal, the cholesteric liquid crystal changes from a homeotropic state to a focal conic state or a planar state.
The method according to claim 1,
Further comprising an orientation portion formed in the electrode portion,
Wherein the alignment unit arranges the cholesteric liquid crystal in a homeotropic manner.
The method according to claim 1,
And an alignment material which is mixed with the cholesteric liquid crystal and arranges a phase of the cholesteric liquid crystal in a homeotropic phase.
The method according to claim 1,
The liquid crystal unit
And a mixture of cholesteric liquid crystals having different pitches.
And a plurality of display portions made of cholesteric liquid crystal,
Wherein the cholesteric liquid crystal has a homeotropic phase that transmits external light without applying a voltage.
The method of claim 12,
Wherein pitches of the cholesteric liquid crystals constituting the plurality of display portions are different or equal to each other.
14. The method of claim 13,
The plurality of display units
Wherein the color of the different series is displayed or the color of the same series is displayed.
The method of claim 12,
The display unit
A first substrate and a second substrate facing each other; And
And an electrode portion formed on the first substrate and the second substrate,
Wherein the cholesteric liquid crystal is formed between the first substrate and the second substrate.

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