KR102640018B1 - Display device capable of performing a mirror function - Google Patents

Abstract

The present invention relates to a display device capable of performing a mirror function. The display device may include a liquid crystal panel and a reflective polarizer positioned in order on the display panel. The liquid crystal panel may include a liquid crystal layer including VA mode liquid crystals in which the liquid crystals rotate according to a vertical electric field. Accordingly, the display device can adjust the amount of external light reflection for each region. Accordingly, in the display device, deterioration of image visibility due to the mirror function can be prevented.

Description

Display device capable of performing a mirror function

The present invention relates to a display device capable of performing a mirror function using external light reflection.

Generally, a display device includes a display panel for displaying an image. For example, the display panel may include a liquid crystal panel including liquid crystal and/or an OLED panel including a light emitting device.

When the display device is not displaying an image, it can perform a mirror function. For example, the display panel of the display device may include reflective electrodes made of a material with high reflectivity. The display device can perform a mirror function by using reflection of external light by the reflective electrode.

However, in the display device, images implemented by the display panel may be affected by external light reflection. That is, the visibility of the image displayed by the display panel of the display device may be reduced due to reflection of external light to perform the mirror function. The display device uses reflective electrodes made of low-reflective materials to prevent deterioration of image visibility due to external light reflection, but there is a problem in that the mirror function cannot be sufficiently performed due to a decrease in the amount of external light reflection. In addition, in the display device, the external light reflectance of the area can be lowered by attaching an optical member in the area where light is emitted in order to implement an image, but the mirror function is not sufficiently performed due to the space between the external light reflection areas, and the optical member does not sufficiently perform the mirror function. There is a problem in that the luminance of light emitted from the display panel is reduced due to this.

The problem to be solved by the present invention is to provide a display device that can sufficiently perform a mirror function by using external light reflection and prevent deterioration of image visibility due to external light reflection.

Another problem to be solved by the present invention is to provide a display device that can reduce the external light reflectance of a specific area without loss of light emitted from the display panel.

The problems to be solved by the present invention are not limited to the problems mentioned above. Problems not mentioned herein will become clear to those skilled in the art from the description below.

A display device according to the technical idea of the present invention for achieving the above-described problem includes a display panel. The display panel implements images provided to the user. A liquid crystal panel is located on the display panel. The liquid crystal panel includes a liquid crystal layer located between a first liquid crystal substrate and a second liquid crystal substrate. The liquid crystal layer includes liquid crystal in VA mode. A reflective polarizer is located on the liquid crystal panel.

The distance between the display panel and the liquid crystal panel may be greater than the distance between the liquid crystal panel and the reflective polarizer.

The liquid crystal panel may further include pixel electrodes, a first alignment layer, a second alignment layer, and a common electrode positioned in that order between the first liquid crystal substrate and the second liquid crystal substrate. The liquid crystal layer may be positioned between the first alignment layer and the second alignment layer. The liquid crystal located within the liquid crystal layer can rotate according to the vertical electric field formed between the corresponding pixel electrode and the common electrode.

The thickness of the liquid crystal layer may be 2 to 3 μm.

The lateral phase retardation value (Rin) of the liquid crystal layer in a driving state in which a driving voltage is applied to the pixel electrode may be greater than the lateral phase retardation value (Rin) of the liquid crystal layer in an undriven state in which a driving voltage is not applied to the pixel electrode. there is. The thickness direction phase retardation value (Rth) of the liquid crystal layer in a driven state may be smaller than the thickness direction phase retardation value (Rth) of the liquid crystal layer in an undriven state.

In an undriven state, the lateral phase retardation value (Rin) of the liquid crystal layer may be 0.

In a driving state, the lateral phase retardation value (Rin) of the liquid crystal layer may be λ/4. The thickness direction phase retardation value (Rth) of the liquid crystal layer may be λ/8.

The driving voltage may be 4 to 5V.

The display panel may include a first display substrate, a light emitting element, and a second display substrate stacked in that order. The first liquid crystal substrate of the liquid crystal panel may be located on the second display substrate of the display panel. An air gap may be located between the display panel and the liquid crystal panel. The vertical length of the air gap may be equal to the vertical distance between the second display substrate and the first liquid crystal substrate.

A display device according to the technical idea of the present invention can reduce the external light reflectance of a specific area by using a liquid crystal panel and a reflective polarizer positioned in order on the display panel. Accordingly, in the display device according to the technical idea of the present invention, deterioration of image visibility due to reflection of external light can be prevented without loss of light emitted from the display panel. Therefore, in a display device according to the technical idea of the present invention, image quality can be improved without deteriorating the mirror function.

1 is a diagram schematically showing a display device according to an embodiment of the present invention.
Figure 2 is an enlarged view of area P in Figure 1.
3A to 3F are diagrams sequentially showing the movement direction and polarization state of external light incident on the undriven area and the driven area of the liquid crystal panel in the display device according to an embodiment of the present invention.
4A to 4G are diagrams sequentially showing the movement direction and polarization state of light emitted from a display panel in a display device according to an embodiment of the present invention.
Figures 5a to 5g are graphs showing the front reflectance and side reflectance of the liquid crystal layer according to the cell gap for each driving voltage.

Details regarding the above-mentioned purpose, technical configuration, and effects thereof of the present invention will be more clearly understood through the following detailed description with reference to the drawings showing embodiments of the present invention. Here, since the embodiments of the present invention are provided so that the technical idea of the present invention can be sufficiently conveyed to those skilled in the art, the present invention may be embodied in other forms so as not to be limited to the embodiments described below.

In addition, parts indicated with the same reference numerals throughout the specification refer to the same components, and the length and thickness of a layer or region in the drawings may be exaggerated for convenience. Additionally, when a first component is described as being “on” a second component, it does not only mean that the first component is located above and in direct contact with the second component, but also that the first component and the It also includes cases where a third component is located between second components.

Here, the terms first, second, etc. are used to describe various components and are used for the purpose of distinguishing one component from other components. However, without departing from the technical spirit of the present invention, the first component and the second component may be arbitrarily named according to the convenience of those skilled in the art.

The terms used in the specification of the present invention are only used to describe specific embodiments and are not intended to limit the present invention. For example, an element expressed in the singular includes plural elements unless the context clearly indicates only the singular. In addition, in the specification of the present invention, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are intended to indicate the presence of one or It should be understood that this does not preclude the existence or addition of other features, numbers, steps, operations, components, parts, or combinations thereof.

Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the specification of the present invention, they should not be taken in an idealistic or excessively formal sense. It is not interpreted.

(Example)

1 is a diagram schematically showing a display device according to an embodiment of the present invention. Figure 2 is an enlarged view of area P in Figure 1.

Referring to Figures 1 and 2, a display device according to an embodiment of the present invention may include a display panel 100. The display panel 100 can implement images to be provided to the user. For example, the display panel 100 may include a light emitting device 140 located between the first display substrate 110 and the second display substrate 180.

The first display substrate 110 may support the light emitting device 140. The first display substrate 110 may include an insulating material. For example, the first display substrate 110 may include glass or plastic.

The light emitting device 140 may emit light representing a specific color. For example, the light-emitting device 140 may include a first light-emitting electrode 141, a light-emitting layer 142, and a second light-emitting electrode 142 stacked in that order.

The first light emitting electrode 141 may be located close to the first display substrate 110 . The first light emitting electrode 141 may include a conductive material. The first light emitting electrode 141 may include a material with high reflectivity. For example, the first light emitting electrode 141 may include metal such as aluminum (Al) and silver (Ag). The first light emitting electrode 141 may have a multilayer structure. For example, the first light emitting electrode 141 may have a structure in which a reflective electrode made of a material with high reflectivity is positioned between transparent electrodes made of a transparent conductive material such as ITO and IZO.

The light emitting layer 142 may generate light with luminance corresponding to the voltage difference between the first light emitting electrode 141 and the second light emitting electrode 142. For example, the light emitting layer 142 may include an light emitting material layer (EML) formed of a light emitting material. The light emitting material may include organic materials, inorganic materials, or hybrid materials. For example, the display panel 100 of the display device according to an embodiment of the present invention may be an OLED panel including a light emitting layer 142 formed of an organic material. The light emitting layer 142 may have a multilayer structure to increase light emission efficiency. For example, the light-emitting layer 142 may further include at least one of a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL).

The second light emitting electrode 143 may include a conductive material. The second light emitting electrode 143 may include a material different from that of the first light emitting electrode 141. For example, the second light emitting electrode 143 may be a transparent electrode made of a transparent conductive material such as ITO and IZO. Accordingly, in the display panel 100 of the display device according to an embodiment of the present invention, light generated by the light-emitting layer 142 may be emitted through the second light-emitting electrode 143.

A thin film transistor 120 and an overcoat layer 130 covering the thin film transistor 120 may be positioned between the first display substrate 110 and the light emitting device 140.

The light emitting device 140 may be controlled by the thin film transistor 120. For example, the thin film transistor 120 may transmit a driving current corresponding to a data signal applied through a data line to the light emitting device 140 according to a gate signal applied through the gate line. The thin film transistor 120 may include a semiconductor pattern, a gate insulating film, a gate electrode, an interlayer insulating film, a source electrode, and a drain electrode. For example, the first light emitting electrode 141 may be electrically connected to the drain electrode of the thin film transistor 120.

The overcoat layer 130 can remove steps caused by the thin film transistor 120. For example, the upper surface of the overcoat layer 130 facing the light emitting device 140 may be a flat plane. The light emitting device 140 may be located on the overcoat layer 130. For example, the overcoat layer 130 may include an electrode contact hole that partially exposes the drain electrode of the thin film transistor 120. The overcoat layer 130 may include an insulating material. For example, the overcoat layer 130 may include an organic insulating material.

The edge of the first light emitting electrode 141 may be covered by the bank insulating film 150. The light emitting layer 142 and the second light emitting electrode 142 may be sequentially stacked on a partial area of the first light emitting electrode 141 exposed by the bank insulating film 150. The light emitting layer 142 and/or the second light emitting electrode 142 may extend onto the bank insulating layer 150 . The bank insulating layer 150 may include an insulating material. For example, the bank insulating layer 150 may include an organic insulating material. The bank insulating layer 150 may include a material different from that of the overcoat layer 130.

An upper protective film 160 and an encapsulation layer 170 may be sequentially stacked between the light emitting device 140 and the second display substrate 180.

The upper protective film 160 can prevent damage to the light emitting device 140 due to external moisture and impact. The light emitting device 140 may be completely covered by the upper protective film 160. For example, the upper protective layer 160 may extend along the light emitting layer 142 and the second light emitting electrode 143. The upper protective layer 160 may extend onto the bank insulating layer 150 . The upper protective film 160 may include an insulating material. For example, the upper protective layer 160 may include an inorganic insulating layer formed of an inorganic material. The upper protective film 160 may have a multilayer structure. For example, the upper protective film 160 may have a structure in which an organic insulating film made of an organic material is positioned between the inorganic insulating films.

The encapsulation layer 170 can alleviate external shock. The encapsulation layer 170 can delay the penetration of external moisture. The encapsulation layer 170 may have a multilayer structure. For example, the encapsulation layer 170 may include a lower encapsulation layer 171 and an upper encapsulation layer 172 sequentially stacked on the upper protective film 160. The upper encapsulation layer 172 may include moisture absorption particles 170p. The moisture-absorbing particles 170p may include a moisture-absorbing material. The lower encapsulation layer 171 can relieve stress applied to the light emitting device 140 by expansion of the moisture absorption particles 170p. The encapsulation layer 170 may include an insulating material. The encapsulation layer 170 may include a material that does not require a hardening process. For example, the encapsulation layer 170 may include an olefin-based material. Accordingly, in the display device according to an embodiment of the present invention, deterioration of the light emitting device 140 due to the forming process of the encapsulation layer 170 can be prevented. The upper encapsulation layer 172 may include a material different from that of the lower encapsulation layer 171.

The second display substrate 180 may be combined with the first display substrate 110 on which the light emitting device 140 is formed by the encapsulation layer 170. For example, the encapsulation layer 170 may include an adhesive material. The encapsulation layer 170 may completely fill the space between the upper protective layer 160 and the second display substrate 180. The second display substrate 180 may include an insulating material. The second display substrate 180 may include a transparent material. For example, the second display substrate 180 may include glass or plastic. Accordingly, in the display device according to an embodiment of the present invention, light generated by the light-emitting layer 142 may be emitted to the outside through the second light-emitting electrode 143 and the second display substrate 180.

A liquid crystal panel 200 and a reflective polarizer 300 may be positioned in that order on the display panel 100. The liquid crystal panel 200 may be located between the display panel 100 and the reflective polarizer 300. Light emitted from the display panel 100 may be transmitted to the user through the liquid crystal panel 200 and the reflective polarizer 300. For example, the liquid crystal panel 200 and the reflective polarizer 300 may be located on the second display substrate 180 of the display panel 100. The liquid crystal panel 200 and the reflective polarizer 300 can selectively change external light reflectance. For example, the liquid crystal panel 200 may include a liquid crystal layer 230 located between the first liquid crystal substrate 210 and the second liquid crystal substrate 220.

The first liquid crystal substrate 210 may be located close to the display panel 100. For example, the outer surface of the first liquid crystal substrate 210 may face the outer surface of the second display substrate 180. The reflective polarizer 300 may be located on the second liquid crystal substrate 220 of the liquid crystal panel 200.

The first liquid crystal substrate 210 and the second liquid crystal substrate 220 may include an insulating material. The first liquid crystal substrate 210 and the second liquid crystal substrate 220 may include a transparent material. For example, the first liquid crystal substrate 210 and the second liquid crystal substrate 220 may include glass or plastic.

The liquid crystal layer 230 may include liquid crystal (LC) in vertical alignment (VA) mode. For example, the liquid crystal (LC) located within the liquid crystal layer 230 may be rotated by a vertical electric field. The liquid crystal panel 200 includes pixel electrodes 240, a first alignment layer 260, and a second alignment layer 270 located in that order between the first liquid crystal substrate 210 and the second liquid crystal substrate 220. and a common electrode 250. The liquid crystal layer 230 may be located between the first alignment layer 260 and the second alignment layer 270.

The pixel electrodes 240 and the common electrode 250 may include a conductive material. The pixel electrodes 240 and the common electrode 250 may include a transparent material. For example, the pixel electrodes 240 and the common electrode 250 may be transparent electrodes made of ITO or IZO. The common electrode 250 may be formed of a material different from that of the pixel electrodes 240.

The pixel electrodes 240 may be spaced apart from each other. Each pixel electrode 240 can be controlled independently. For example, the voltage applied to each pixel electrode 240 may be different from the voltage applied to the adjacent pixel electrode 240. Liquid crystal (LC) located in the liquid crystal layer 230 may be rotated according to the vertical electric field formed between the corresponding pixel electrode 240 and the common electrode 250. Accordingly, the display device according to an embodiment of the present invention can adjust the external light reflectance for each region through the state of the liquid crystal (LC) located in the liquid crystal layer 230.

The reflective polarizer 300 may reflect light polarized in a first direction. Light polarized in the second direction may pass through the reflective polarizer 300. The second direction may be perpendicular to the first direction. For example, the reflective polarizer 300 may be a dual bright enhancement film (DBEF).

FIGS. 3A to 3F are diagrams sequentially showing the movement direction and polarization state of external light incident on the undriven region (R1) and the driven region (R2) of the liquid crystal panel 200 in the display device according to an embodiment of the present invention.

External light reflection depending on the operating state of the liquid crystal panel 200 in the display device according to an embodiment of the present invention will be described with reference to FIGS. 3A to 3F. First, as shown in FIG. 3A, in the display device according to an embodiment of the present invention, the reflective polarizer 300 located on the liquid crystal panel 200 including the undriven region R1 and the driving region R2 External light can enter.

The non-driving region R1 may refer to an area in which a driving voltage is not applied to the pixel electrode 240 of the liquid crystal panel 200. Liquid crystals (LC) arranged in a vertical direction may be located in the liquid crystal layer 230 of the undriven region (R1). That is, in the display device according to an embodiment of the present invention, the lateral phase retardation value (Rin) of the liquid crystal layer 230 may be 0 in an undriven state in which a driving voltage is not applied to the pixel electrode.

The driving area R2 may refer to an area where a driving voltage is applied to the pixel electrode 240. A vertical electric field may be formed within the liquid crystal layer 230 of the driving region R2 by the driving voltage applied to the pixel electrode 240. Liquid crystal LC located within the liquid crystal layer 230 of the driving region R2 may be rotated by a vertical electric field. Rotation of the liquid crystal LC adjacent to the first alignment layer 260 covering the pixel electrodes 230 and the second alignment layer 270 covering the common electrode 250 may be suppressed by an anchoring effect. there is. Accordingly, in the display device according to an embodiment of the present invention, the rotation angle of the liquid crystal (LC) located within the liquid crystal layer 230 of the driving region (R2) increases as the distance from the alignment layer (260, 270) increases. You can. For example, in the display device according to an embodiment of the present invention, the liquid crystal (LC) located in the liquid crystal layer 230 of the driving region R2 maintains vertical alignment near the alignment layers 260 and 270, The rotation angle may gradually increase as the distance from the alignment layers 260 and 270 increases. The liquid crystal LC located within the liquid crystal layer 230 of the driving region R2 may have horizontal alignment at a midpoint between the first alignment layer 260 and the second alignment layer 270. That is, in the display device according to an embodiment of the present invention, in a driving state in which a driving voltage is applied to the pixel electrode 230, the lateral phase retardation value (Rin) of the liquid crystal layer 230 is applied to the pixel electrode 230. In an undriven state where no driving voltage is applied, the lateral phase retardation value (Rin) of the liquid crystal layer 230 may be greater than the lateral phase retardation value (Rth) of the liquid crystal layer 230 in the driving state. In the undriven state, it may be smaller than the thickness direction phase retardation value (Rth) of the liquid crystal layer 230.

As shown in FIG. 3B, in the display device according to an embodiment of the present invention, external light incident on the reflective polarizer 300 may be partially reflected by the reflective polarizer 300.

The polarization direction of light passing through the reflective polarizer 300 may be different from the polarization direction of light reflected by the reflective polarizer 300. For example, the polarization direction of light reflected by the reflective polarizer 300 may be perpendicular to the polarization direction of light passing through the reflective polarizer 300. The light reflected by the reflective polarizer 300 may be linearly polarized in the first direction. The light passing through the reflective polarizer 300 may be linearly polarized in a second direction perpendicular to the first direction.

As shown in FIG. 3C, in the display device according to an embodiment of the present invention, light linearly polarized by the reflective polarizer 300 is transmitted to the undriven region R1 and the driven region R2 of the liquid crystal panel 200. ) can pass.

Since the liquid crystals (LC) located in the liquid crystal layer 230 are vertically aligned, the undriven region (R1) of the liquid crystal panel 200 is Light incident on can pass through the liquid crystal panel 200 without changing the polarization direction. For example, light passing through the undriven region R1 of the liquid crystal panel 200 from the reflective polarizer 300 toward the display panel 100 may be linearly polarized in the second direction.

Since the liquid crystal (LC) located in the liquid crystal layer 230 is rotated by a vertical electric field, the driving region R2 of the liquid crystal panel 200 is linearly polarized in the second direction by the reflective polarizer 300. The light may be circularly polarized by the liquid crystal layer 230 in the driving region R2. For example, light passing through the driving region R2 of the liquid crystal panel 200 from the reflective polarizer 300 toward the display panel 100 may be left circularly polarized light.

As shown in FIG. 3D, in the display device according to an embodiment of the present invention, light passing through the liquid crystal panel 200 and traveling toward the display panel 100 may be reflected by the display panel 100. there is.

Light traveling in the direction of the display panel 100 may be reflected by a layer formed of a reflective material located within the display panel 100. For example, light incident on the display panel 100 may be reflected by the first light-emitting electrode of the light-emitting device.

Since the light passing through the undriven region R1 of the liquid crystal panel 200 is linearly polarized in the second direction, the polarization direction may not be changed by reflection of the display panel 100. For example, in the display device according to an embodiment of the present invention, after passing through the undriven region R1 of the liquid crystal panel 200, the light reflected by the display panel 100 is directed in the second direction. It may be linearly polarized light.

Since the light passing through the driving region R2 of the liquid crystal panel 200 is circularly polarized light, the polarization direction may be reversed by reflection from the display panel 100. For example, in a display device according to an embodiment of the present invention, light reflected by the display panel 100 after passing through the driving region R2 of the liquid crystal panel 200 may be right-circularly polarized light. .

As shown in FIG. 3E, in the display device according to an embodiment of the present invention, the light reflected by the display panel 100 is transmitted to the non-driving area R1 and the driving area R2 of the liquid crystal panel 200. ) may proceed in the direction of the reflective polarizer 300.

Since the liquid crystals (LC) located in the liquid crystal layer 230 of the undriven region R1 of the liquid crystal panel 200 are vertically aligned, the light reflected by the display panel 100 is directed in the polarization direction. may pass through the undriven region R1 of the liquid crystal panel 200 without change. For example, light reflected by the display panel 100 and passing through the undriven region R1 of the liquid crystal panel 200 may be linearly polarized in the second direction.

The driving region R2 of the liquid crystal panel 200 has the polarization direction of the light reflected by the display panel 100 because the liquid crystal (LC) located in the liquid crystal layer 230 is rotated by a vertical electric field. can be changed by the driving area R2 of the liquid crystal panel 200. That is, circularly polarized light reflected by the display panel 100 and traveling toward the reflective polarizer 300 may be linearly polarized by the driving region R2 of the liquid crystal panel 200. For example, light reflected by the display panel 100 and passing through the driving region R2 of the liquid crystal panel 200 may be linearly polarized in the first direction.

As shown in FIG. 3F, in the display device according to an embodiment of the present invention, the light is reflected by the display panel 100 and forms the non-driving area R1 and the driving area R2 of the liquid crystal panel 200. The light that passes may be reflected by the reflective polarizer 300 or may pass through the reflective polarizer 300 depending on the polarization state.

Since the reflective polarizer 300 reflects light linearly polarized in the first direction, the light reflected by the display panel 100 and passing through the undriven region R1 of the liquid crystal panel 200 is reflected. It can pass through the polarizer 300. Accordingly, in the display device according to an embodiment of the present invention, the undriven area R1 of the liquid crystal panel 200 can sufficiently perform a mirror function.

Since the light reflected by the display panel 100 and passing through the driving region R2 of the liquid crystal panel 200 is linearly polarized in the first direction, the reflective polarizer 300 is used to polarize the display panel 100. ) may reflect light that has passed through the driving region R2 of the liquid crystal panel 200. Accordingly, in the display device according to an embodiment of the present invention, the external light reflectance of the driving area R2 of the liquid crystal panel 200 may be reduced. Therefore, in the display device according to an embodiment of the present invention, the external light reflectance can be adjusted for each region through the driving state of the liquid crystal layer 230.

FIGS. 4A to 4G are diagrams sequentially showing the movement direction and polarization state of light emitted from the display panel 100 in a display device according to an embodiment of the present invention.

The emission path of light emitted from the display panel 100 in the display device according to an embodiment of the present invention will be described with reference to FIGS. 4A to 4G. First, as shown in FIG. 4A, in the display device according to an embodiment of the present invention, light for implementing an image is emitted in a partial area of the display panel 100 corresponding to the driving area R2 of the liquid crystal panel 200. may be released.

As shown in FIG. 4B, in the display device according to an embodiment of the present invention, light emitted from the display panel 100 passes through the driving region R2 of the liquid crystal panel 200 and enters the reflective polarizer 300. ) direction.

Since no optical member is disposed between the display panel 100 and the liquid crystal panel 200, the light emitted by the display panel 100 and incident on the liquid crystal panel 200 is not polarized in a specific direction. It could be light. Accordingly, in the display device according to an embodiment of the present invention, light passing through the driving region R2 of the liquid crystal panel 200 may be light that is not polarized in a specific direction.

As shown in FIG. 4C, in the display device according to an embodiment of the present invention, light passing through the liquid crystal panel 200 may be partially reflected by the reflective polarizer 300.

Since the reflective polarizer 300 reflects light linearly polarized in a first direction, light linearly polarized in a second direction perpendicular to the first direction may pass through the reflective polarizer 300 and be emitted to the outside.

As shown in FIG. 4D, in the display device according to an embodiment of the present invention, the light reflected by the reflective polarizer 300 passes through the driving region R2 of the liquid crystal panel 200 and enters the display panel ( You can proceed in the 100) direction.

Since the light reflected by the reflective polarizer 300 is linearly polarized in the first direction, and the liquid crystal (LC) rotated by the vertical electric field is located in the liquid crystal layer 230 of the driving region (R2), Light reflected by the reflective polarizer 300 may be circularly polarized by the liquid crystal panel 200. For example, light reflected by the reflective polarizer 300 and passing through the driving region R2 of the liquid crystal panel 200 may be right-circularly polarized light.

As shown in FIG. 4E, in the display device according to an embodiment of the present invention, light reflected by the reflective polarizer 300 and passing through the driving region R2 of the liquid crystal panel 200 is transmitted to the display panel ( 100) can be reflected.

Since the light reflected by the reflective polarizer 300 and passing through the driving region R2 of the liquid crystal panel 200 is right-circularly polarized light, the light passing through the driving region R2 of the liquid crystal panel 200 Afterwards, the light reflected by the display panel 100 may be left circularly polarized light.

As shown in FIG. 4F, in the display device according to an embodiment of the present invention, the light reflected by the display panel 100 passes back through the driving region R2 of the liquid crystal panel 200 and is transmitted to the reflective polarizer. You can proceed in the (300) direction.

Since the light reflected by the display panel 100 is left circularly polarized light, the light passing back through the driving region R2 of the liquid crystal panel 200 and incident on the reflective polarizer 300 is directed in the second direction. It may be linearly polarized light.

As shown in FIG. 4G, in the display device according to an embodiment of the present invention, light that has passed through the driving region R2 of the liquid crystal panel 200 again by reflection of the display panel 100 is transmitted to the reflective polarizer. It may pass through (300) and be released to the outside. Accordingly, in the display device according to an embodiment of the present invention, the polarization state of the light reflected by the reflective polarizer 300 is changed by the driving region R2 of the liquid crystal panel 200 and re-emitted, so that the image For the implementation, loss of emitted light can be prevented. Therefore, in the display device according to an embodiment of the present invention, loss of light emitted from the display panel 100 can be prevented.

In the display device according to an embodiment of the present invention, light emitted by the display panel 100 may be incident on the liquid crystal panel 200 without being polarized in a specific direction in order to implement an image. That is, as shown in FIG. 1, in the display device according to an embodiment of the present invention, an optical member may not be located between the display panel 100 and the liquid crystal panel 200. For example, in the display device according to an embodiment of the present invention, the vertical length of the air gap AG is equal to the distance between the second display substrate 180 of the display panel 100 and the first display substrate 180 of the liquid crystal panel 200. It may be the same as the separation distance d1 between the liquid crystal substrates 210.

In the display device according to an embodiment of the present invention, the separation distance d1 between the display panel 100 and the liquid crystal panel 200 is adjusted to emit light from the display panel 100 to the reflective polarizer 300. Destructive interference can be prevented between light that is not reflected and light emitted to the outside by reflection of the reflective polarizer 300 and the display panel 100. For example, in the display device according to an embodiment of the present invention, the separation distance d1 between the display panel 100 and the liquid crystal panel 200 is the distance between the liquid crystal panel 200 and the reflective polarizer 300. It may be larger than the separation distance (d2).

In the display device according to an embodiment of the present invention, in a driving state, the lateral phase retardation value (Rin) of the liquid crystal layer 230 is λ/4, and the thickness direction phase retardation value (Rth) of the liquid crystal layer 230 is λ/4. By adjusting it to have λ/8, the reflectance in the front direction and the reflectance in the side direction can be sufficiently reduced.

5A to 5G show the front reflectance (Rf) and side reflectance (Rv) of the liquid crystal layer according to the cell gap when driving voltages of 0V, 2V, 3V, 4V, 4.5V, 5V, and 6V are applied, respectively. These are graphs showing .

Referring to FIGS. 5A to 5G, it can be seen that when the cell gap, or the thickness of the liquid crystal layer, is 2 to 3 μm, the front reflectance (Rf) and the side reflectance (Rv) rapidly decrease depending on the driving voltage. Accordingly, in the display device according to an embodiment of the present invention, the liquid crystal layer of the liquid crystal panel has a thickness of 2 to 3 μm, so that the difference in external light reflectance between the driven and undriven states can be maximized. Additionally, referring to FIGS. 5A to 5G, it can be seen that the front reflectance (Rf) and the side reflectance (Rv) have their lowest values at a driving voltage of 4 to 5V. Accordingly, in the display device according to an embodiment of the present invention, a driving voltage of 4 to 5V can be applied to the liquid crystal panel to maximize the difference in external light reflectance between the driven and non-driven states.

As a result, the display device according to an embodiment of the present invention stacks the liquid crystal panel 200 and the reflective polarizer 300 in that order on the display panel 100, and corresponds to the area where light is emitted from the display panel 100. By applying a driving voltage to the driving region R2 of the liquid crystal panel 200, the external light reflectance of the region can be lowered without loss of light emitted from the display panel 100. Accordingly, the display device according to an embodiment of the present invention sufficiently performs the mirror function, and deterioration of visibility of the image implemented by the display panel 100 can be prevented. In addition, in the display device according to an embodiment of the present invention, the external light reflectance is adjusted depending on whether the liquid crystal layer 230 is driven, so the position of the image implemented by the display panel 100 and the position of the mirror can be arranged in various ways. . That is, in the display device according to an embodiment of the present invention, switching between the area that performs the mirror function and the area that implements the image can be quickly and easily performed. Therefore, image quality and usability can be improved in the display device according to an embodiment of the present invention.

100: display panel 200: liquid crystal panel
210: first liquid crystal substrate 220: second liquid crystal substrate
230: liquid crystal layer 240: pixel electrode
250: common electrode 260: first alignment layer
270: second alignment layer 300: reflective polarizer
LC: liquid crystal

Claims (9)

A display panel that displays images;
a liquid crystal panel located on the display panel and including a liquid crystal layer located between a first liquid crystal substrate and a second liquid crystal substrate; and
Includes a reflective polarizer located on the liquid crystal panel,
The liquid crystal layer includes VA mode liquid crystal,
The display panel and the liquid crystal panel are spaced apart from each other by a distance d1, and the liquid crystal panel and the reflective polarizer are spaced apart from each other by a distance d2, and the separation distance d1 is greater than the separation distance d2. bigger,
Display device. delete According to claim 1,
The liquid crystal panel further includes pixel electrodes, a first alignment layer, a second alignment layer, and a common electrode positioned in that order between the first liquid crystal substrate and the second liquid crystal substrate,
The liquid crystal layer is located between the first alignment layer and the second alignment layer,
A display device in which the liquid crystal located in the liquid crystal layer rotates according to a vertical electric field formed between the corresponding pixel electrode and the common electrode. According to claim 3,
A display device wherein the liquid crystal layer has a thickness of 2 to 3 μm. According to claim 3,
In a driving state in which a driving voltage is applied to the pixel electrode, the lateral phase retardation value (Rin) of the liquid crystal layer is changed to the lateral phase retardation value (Rin) in the liquid crystal layer in an undriven state in which a driving voltage is not applied to the pixel electrode. ) is greater than
A display device wherein a thickness direction phase retardation value (Rth) of the liquid crystal layer in the driven state is smaller than a thickness direction phase retardation value (Rth) of the liquid crystal layer in the undriven state. According to claim 5,
A display device in which the lateral phase retardation value (Rin) of the liquid crystal layer in the non-driving state is 0. According to claim 5,
In the driving state, the lateral phase retardation value (Rin) of the liquid crystal layer is λ/4, and the thickness direction phase retardation value (Rth) of the liquid crystal layer is λ/8. According to claim 5,
A display device wherein the driving voltage is 4 to 5V. According to claim 1,
The display panel includes a first display substrate, a light emitting element, and a second display substrate stacked in order,
The first liquid crystal substrate of the liquid crystal panel is located on the second display substrate of the display panel,
A display device wherein the vertical length of the air gap located between the display panel and the liquid crystal panel is equal to the vertical distance between the second display substrate and the first liquid crystal substrate.

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