KR20180127569A - Reflective liquid crystal film and display device including the same - Google Patents

Abstract

According to embodiments of the present invention, a reflective liquid crystal film and a display device having the same are disclosed. According to embodiments of the present invention, the display device comprises: a display panel; a backlight unit arranged on a rear surface of the display panel, and including a light source assembly; and the reflective liquid crystal film positioned at a position where a light emitted from the light source assembly is incident, and including a cholesteric liquid crystal layer with at least one layer including a plurality of liquid crystal molecules, wherein the peak of a central wavelength is 430 nm, and the half-power width is 42 nm. Therefore, the color reproduction range of a color corresponding to a specific wavelength and the brightness of the display device can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reflective liquid crystal film, and a display device including the reflective liquid crystal film. 2. Description of the Related Art Reflective liquid crystal films

These embodiments relate to a reflection type liquid crystal film and a display device including the same.

A liquid crystal display (LCD) is a device for displaying an image by injecting liquid crystal between two glass plates and applying power to the upper and lower glass plate electrodes to change the arrangement of liquid crystal molecules in each pixel. Unlike a cathode ray tube (CRT), a plasma display panel (PDP) or the like, a display using a liquid crystal display device is not usable in a place where there is no light because the display itself is non-luminous. In order to compensate for these drawbacks, an illumination device such as a light source assembly is mounted on the information display surface uniformly for the purpose of enabling use in a dark place.

The light source assembly used in the liquid crystal display device is divided into two types. The first is an edge type light source assembly that provides light at the side of the liquid crystal display device and the second is a direct light type light source assembly that provides light directly at the back side of the liquid crystal display device. In the case of the edge type light source assembly, a light guide plate is provided so that light emitted from a light source is irradiated upward, and at least one optical plate is provided above the light guide plate to control optical characteristics of light passing through the light guide plate. In the case of a direct-type light source assembly, a diffusion plate may be provided to reduce a light line of light emitted from a light source, and at least one optical sheet is provided to control the optical characteristics of light passing through the diffusion plate.

Further, such a liquid crystal display device includes a polarizing plate disposed on the top and bottom of the display panel. The upper polarizer located above the display panel includes a surface treatment layer for separating the light incident from the display panel into the wavelength of red light and the wavelength of green light or is used to attach the upper polarizer to a display panel A light absorbing material is contained in the pressure-sensitive adhesive (or adhesive) layer.

However, in such a case, since there is no means for branching to the wavelength of blue light in the upper polarizer, the light emitted to the outside from the display panel 100 has a low color reproduction rate. In addition, since a new substance is required to separate the wavelength corresponding to blue light through the light absorbing substance, there is a problem that it is difficult to adjust the light absorbing band with the existing light absorbing substance.

The embodiments of the present invention are directed to solving the above problems and provide a reflective liquid crystal film and a display device including the reflective liquid crystal film capable of improving color reproducibility.

A reflection type liquid crystal film according to an exemplary embodiment includes at least one cholesteric liquid crystal layer including a plurality of liquid crystal molecules, and has a peak at a center wavelength of reflected light of 430 nm and a peak And the half width is 42 nm.

The reflection type liquid crystal film and the display device including the same according to another embodiment of the present invention are disposed on the back surface of the display panel and the display panel and are positioned at a position where the light emitted from the backlight unit and the light source assembly including the light source assembly are incident, Of a cholesteric liquid crystal layer containing at least one layer of liquid crystal molecules and having a peak at a center wavelength of 430 nm and a half width of a peak of 42 nm.

Since the display device according to the present embodiments includes the anti-use liquid crystal film, the luminance is improved by the recycling phenomenon caused by the retroreflective light continuously reflected by the anti-use liquid crystal film, There is an effect that the color recall ratio is increased.

1 is a view showing a display device according to a first embodiment.
2 is a graph showing a center wavelength and a half width of reflected light of the reflection type liquid crystal film according to the first embodiment.
Fig. 3 is a view showing a principle in which light of a specific wavelength is recycled by the reflection type liquid crystal film in the display device according to the first embodiment. Fig.
4 is a graph comparing the wavelength of light incident on the display panel due to the reflection type liquid crystal film according to the present embodiment and the wavelength of light incident on the display panel of the display device according to the comparative example.
5 is a graph showing the blue color coordinates of the display device according to the comparative example, the color coordinates of the DCI-P3 blue standard, and the blue color coordinates of the display device according to the present embodiment.
6 is a diagram showing a display device according to the second embodiment.
7 is a view showing a display device according to the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of the layers and regions in the figures may be exaggerated for clarity of illustration.

It will be understood that when an element or layer is referred to as being another element or "on" or "on ", it includes both intervening layers or other elements in the middle, do. On the other hand, when a device is referred to as "directly on" or "directly above ", it does not intervene another device or layer in the middle.

The terms spatially relative, "below," "lower," "above," "upper," and the like, And may be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprise "and / or" comprising ", as used in the specification, means that the presence of stated elements, Or additions.

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

1 is a view showing a display device according to a first embodiment. Referring to FIG. 1, a display device according to the first embodiment includes a display panel 100 and a backlight unit 200. The display panel 100 includes a cell 110 including a lower substrate, an upper substrate and a liquid crystal layer, polarizers 120 and 130 disposed on the lower and upper portions of the cell, Film 250 as shown in FIG. Although not shown in the drawing, the display apparatus according to the present embodiment may further include a driving unit for driving the display panel 100. At this time, at least one driving unit may be mounted in the display panel 100 However, the present embodiment is not limited thereto.

1, the cell of the display panel 100 includes an upper substrate and a lower substrate, and includes a liquid crystal layer interposed between the upper substrate and the lower substrate. At this time, a plurality of thin film transistors may be disposed on the lower substrate, and a plurality of color filter layers may be disposed on one surface of the upper substrate. However, the display panel 100 according to the present embodiment is not limited to this, and a plurality of color filter layers may be disposed on each sub-pixel on the lower substrate.

A common electrode and a pixel electrode are formed in the cell 110 of the display panel 100 in which the upper substrate and the lower substrate are bonded together to apply an electric field to the liquid crystal layer. Data applied to the pixel electrode in a state where a voltage is applied to the common electrode When the voltage of the signal is controlled, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode, thereby transmitting or blocking light for each pixel to display characters or images. In order to control the voltage of the data signal applied to the pixel electrode on a pixel-by-pixel basis, a switching element such as a thin film transistor is separately provided in the pixels.

The upper polarizer 130 is disposed on the cell 110 and the lower polarizer 120 is disposed on the lower side of the cell 110. The lower polarizer 120 polarizes the light transmitted through the backlight unit 200 and the upper polarizer 130 polarizes the light transmitted through the display panel.

The backlight unit 200 includes a plurality of optical sheets 230, a light guide plate 220, and a light source assembly 210 disposed under the display panel 100.

Specifically, the backlight unit 200 includes a plurality of optical sheets 230 disposed on the back surface of the display panel 100. The backlight unit 200 includes a light guide plate 220 disposed on the back surface of the plurality of optical sheets 230 and a light source assembly 210 generating light on at least one side of the light guide plate 220.

The plurality of optical sheets 230 include a diffusion sheet 231, a lower prism sheet 232, and an upper prism sheet 233, and optionally a protective sheet may be further added. The lower prism sheet 232 may be positioned on the diffusion sheet 231 and the upper prism sheet 233 may be positioned on the lower prism sheet 231. [ Lt; RTI ID = 0.0 > 232 < / RTI >

The diffusion sheet 231 disperses the light incident from the light guide plate 220 so that the light is partially densely packed to prevent unevenness in the image displayed on the display panel 100. The diffusion sheet 231 diffuses light incident from the light guide plate 220 The angle is refracted vertically. The lower prism sheet 232 and the upper prism sheet 233 collect light incident from the diffusion sheet 231 and uniformly distribute the light on the entire surface of the display panel 100. In addition, the protective sheet may protect the optical sheet 230 sensitive to dust or scratches, and may prevent the optical sheets 230 from flowing when carrying the backlight unit.

The light guide plate 220 disposed on the back surface of the plurality of optical sheets 230 can convert the light emitted from the light source assembly 210 provided on at least one side of the light guide plate 220 into planar light and irradiate the light to the display panel 100 have. Meanwhile, the light guide plate 220 according to the present embodiment may be inclined.

1, when the light source assembly 210 is provided on only one side of the light guide plate 220, the light source assembly 210 may be disposed in a region of the light guide plate 220 including the light incident side from which the light is incident. The thickness of the light guide plate 220 may be thinner as the distance from the light source assembly 210 increases. Accordingly, it is possible to prevent the incidence of bright spots due to the nonuniformity of light incident on the light guide plate 220.

However, the present embodiment is not limited to this, and the light source assembly 210 may be disposed on at least two sides of the light guide plate 220, and the light guide plate 220 may have a rectangular parallelepiped shape having a uniform thickness. In order to improve the uniformity of the light incident on the light guide plate 220, a plurality of protrusions may be further provided on the upper surface, the back surface, the upper surface, and the back surface of the light guide plate 220.

A light source assembly 210 is provided on only one side of the light guide plate 220 and the thickness of the light guide plate 220 including the light incident side from which light is incident from the light source assembly 210 is the largest And the thickness of the light guide plate 220 decreases as the distance from the light source assembly 210 increases.

The light source assembly 210 provided on at least one side surface of the light guide plate 220 includes a light source array 201 and a light source printed circuit board (PCB) for driving the light source array 201. On the other hand, a plurality of light sources may be provided on the light source printed circuit board at regular intervals.

The light source assembly 202 is mounted on the light source housing 202. In addition to the light source assembly protection, the light source housing 202 can concentrate light emitted from a plurality of light sources toward the light guide plate 220 to prevent light loss. In addition, the light source housing 202 may serve to improve the heat radiation effect of the light source assembly.

Although not shown in the drawing, a reflection plate may be further disposed on the back surface of the light guide plate 320. [ The light emitted from the light source array 201 according to the present embodiment is incident on the side surface of the light guide plate 220. The reflection plate disposed on the back surface of the light guide plate 220 guides the light transmitted through the back surface of the light guide plate 220 to the light guide plate 220, And is reflected toward the plurality of optical sheets 230 on the upper surface so that light is emitted in the direction of the display panel 100.

In addition, the backlight unit 200 according to the present embodiment may further include a cover bottom for receiving the light guide plate 320, and a guide panel for supporting the display panel 100.

The upper polarizer 130 includes a surface treatment layer for separating the light incident from the display panel 100 into a wavelength of red light and a wavelength of green light, (Or adhesive) layer used to adhere to the panel 100. The light- This improves color purity by reducing interference between red light and green light.

However, in such a case, since there is no means for branching to the wavelength of blue light in the upper polarizer 130, the light emitted to the outside from the display panel 100 has a blue wavelength region, So that the color reproduction rate is lowered. Further, since the light absorbing zone of the light absorbing substance is an intrinsic property of the material, it is necessary to develop a new substance to adjust the light absorbing band through the light absorbing substance. That is, in order to separate the wavelength corresponding to the blue light through the light absorbing material, a new substance is required, so that it is difficult to adjust the light absorbing band with the existing light absorbing substance.

The display device according to the first embodiment solves this problem and includes a reflective liquid crystal film 250 disposed between the display panel 100 and the backlight unit 200. More specifically, the reflection type liquid crystal film 250 may be attached to the lower polarizer 120 of the display panel 100. The reflection type liquid crystal film 250 is attached to the lower polarizing plate 120 of the display panel 100 so that light generated from the light source assembly 210 can be incident on the reflection type liquid crystal film 250 through the backlight unit 200 have.

The reflection type liquid crystal film 250 includes a cholesteric liquid crystal layer including a cholesteric liquid crystal (or chiral nematic liquid crystal). The cholesteric liquid crystal may include a nematic liquid crystal and a chiral dopant, but the present embodiment is not limited thereto. A cholesteric liquid crystal has a constant pitch and has a helically twisted structure repeatedly twisted. Repeated twisted spiral structures induce Bragg reflection of light.

The reflective liquid crystal film 250 including the cholesteric liquid crystal layer may be a single layer as shown in FIG. 1, but the present embodiment is not limited thereto. The cholesteric liquid crystal molecules of the cholesteric liquid crystal layer included in the reflection type liquid crystal film 250 may all be made of the same material. This can lead to the same optical properties in all regions of the cholesteric liquid crystal layer.

Cholesteric liquid crystals are classified as right-handed cholesteric liquid crystals and lefthanded cholesteric liquid crystals according to the twisted direction of the helical structure. The primary cholesteric liquid crystal reflects the right circularly polarized light but transmits the left circularly polarized light. The left-handed cholesteric liquid crystal transmits the right-handed polarized light but reflects the left-handed polarized light.

That is, when light including left and right circularly polarized light is incident from outside, the cholesteric liquid crystal layer reflects light of a wavelength corresponding to the liquid crystal pitch of each of the left and right circularly polarized light. For example, when the cholesteric liquid crystal layer includes the preferential cholesteric liquid crystal, when the light including the left and right circularly polarized light is incident from the outside, the cholesteric liquid crystal layer reflects the right circularly polarized light, And reflects light of a wavelength corresponding to the liquid crystal pitch of each region of the polarized light.

The pitch of the cholesteric liquid crystals is related to the wavelength of the reflected light. The central wavelength of the reflected light reflected by the cholesteric liquid crystal is generally proportional to the liquid crystal pitch. Here, the center wavelength of the reflected light can mean the wavelength that is the maximum reflected within the band width or the average wavelength of the band width when the reflected light reflected by the cholesteric liquid crystal has a predetermined band width.

That is, the center wavelength of the reflected light of the reflection type liquid crystal film 250 including the cholesteric liquid crystal layer can be determined by the average refractive index of the cholesteric liquid crystal and the pitch of the cholesteric liquid crystal, and the spiral structure of the cholesteric liquid crystal The circularly polarized light reflected along the twisted direction of the prism can be determined.

The reflective liquid crystal film 250 including the cholesteric liquid crystal layer according to the present embodiment may have a pitch of the cholesteric liquid crystal of 275 nm to 280 nm and a refractive index of the liquid crystal of 1.53 to 1.56. Accordingly, the peak width of the central wavelength of the reflected light of the reflection type liquid crystal film 250 and the half width of the peak can be adjusted.

This will be described in detail with reference to FIG. FIG. 2 is a graph showing the center wavelength and the half-width of the reflected light of the reflection type liquid crystal film according to the first embodiment (transmittance and reflectance measurements are carried out three times (transmittance 1 to 3, reflectance 1 to 3) ).

The wavelength range of the reflected light of the reflective liquid crystal film according to this embodiment may be from 370 nm to 500 nm. Specifically, the peak of the center wavelength of the reflected light is 430 nm and the half width of the peak is 42 nm. That is, the wavelength of the reflected light mainly reflected through the reflection type liquid crystal film may be 388 nm to 472 nm. As described above, the peak of the central wavelength of the reflected light of the reflection type liquid crystal film is 430 nm and the half width of the peak is 42 nm, so that a part of the light mainly in the wavelength range of 388 to 472 nm of the light incident on the reflection type liquid crystal film 250 is reflected and transmitted .

Specifically, the reflection type liquid crystal film according to the present embodiment can reflect light having a center wavelength peak of 430 nm and a peak half width of 42 nm by 12% to 50%, and the reflection type liquid crystal film according to this embodiment has a center 50% to 88% of light having a wavelength peak of 430 nm and a half-width of 42 nm can be transmitted. Also, the reflection type liquid crystal film according to the present embodiment can reflect 46% to 50% of light having a wavelength of 430 nm and transmit 50% to 54% of light having a wavelength of 430 nm.

1 and 2, the reflective liquid crystal film 250 according to the present embodiment has a structure in which a part of light having a center wavelength peak of 430 nm and a peak half width of 42 nm among the light provided from the backlight unit 200 is displayed The remaining part of the light having a peak wavelength of 430 nm and a peak half width of 42 nm can be reflected in the direction of the backlight unit 200. The reflection type liquid crystal film 250 transmits the light of the remaining wavelength band except for the light having the center wavelength of 430 nm and the half width of the peak of 42 nm in the direction of the display panel 100. The peak of the central wavelength is 430 nm and the half width of the peak This is because the light of the remaining wavelength band excluding the light of 42 nm is not included in the band width of the reflected light of the reflection type liquid crystal film 250.

On the other hand, a part of the light reflected by the reflection type liquid crystal film 250 among lights having a center wavelength of 430 nm and a half-width of 42 nm may be recycled and incident on the display panel 100. This configuration will be described below with reference to FIG.

Fig. 3 is a view showing a principle in which light of a specific wavelength is recycled by the reflection type liquid crystal film in the display device according to the first embodiment. Fig. The display device according to Fig. 3 may include the same components as those of Fig. 1 described above. The description overlapping with FIG. 1 described above can be omitted. The same components have the same reference numerals.

3, the display device according to the first embodiment includes a display panel 100, a display panel 100, a backlight unit 200 disposed on the back surface of the display panel 100, And a reflection type liquid crystal film 250 attached to the back surface of the liquid crystal display panel 120. Here, the reflection type liquid crystal film 250 may be provided between the display panel 100 and the backlight unit 200.

The light generated from the light source assembly 210 in the display device according to the first embodiment reaches the reflective liquid crystal film 250 attached to the back surface of the lower polarizer 120 through the light guide plate 220 and the plurality of optical sheets 230 do. The reflection type liquid crystal film 250 includes a cholesteric liquid crystal layer so that it can reflect a part of light in a specific wavelength range and transmit the remaining part.

More specifically, the reflection type liquid crystal film 250 can transmit a part (a) of light having a center wavelength peak of 430 nm and a peak half width of 42 nm among the light provided from the backlight unit 200 in the direction of the display panel 100 And the remaining part (b) of the light having a center wavelength of 430 nm and a peak half width of 42 nm is reflected toward the backlight unit 200.

The light reflected toward the backlight unit 200 is reflected by the reflection plate disposed on the back surface of the light guide plate 220 to reach the reflection type liquid crystal film 250 and a part of the light reaching the reflection type liquid crystal film 250 May be transmitted in the direction of the display panel 100, and the remaining part may be reflected in the direction of the backlight unit 200. That is, the light reflected by the reflection type liquid crystal film 250 in the direction of the backlight unit 200 is continuously reflected again between the reflection plate of the backlight unit 200 and the reflection type liquid crystal film 250, the recycling effect can be obtained and the brightness of the display panel 100 can be improved.

By using the reflective liquid crystal film 250 according to the present embodiment, light generated from the light source assembly 210 can be incident on the display panel 100 without being incident on the display panel 100, You can re-enter. On the other hand, the re-incident light can be incident on the display panel 100 in a state where its wavelength is converted. This configuration will be described with reference to FIG.

4 is a graph comparing the wavelength of light incident on the display panel due to the reflection type liquid crystal film according to the present embodiment and the wavelength of light incident on the display panel of the display device according to the comparative example. Here, the display device according to the comparative example means a display device not including the reflective liquid crystal film according to the present embodiment. That is, the display device according to the comparative example includes only the display panel and the backlight unit disposed on the back surface of the display panel.

Referring to FIG. 4, among the light incident on the display panel of the display device according to the present embodiment, the peak corresponding to the blue light is a blue light among the light incident on the display panel of the display device according to the comparative example. Is shifted in the direction of the longer wavelength with respect to the peak corresponding to the peak wavelength.

That is, in the display device according to the present embodiment, light recycling phenomenon occurs due to the anti-use liquid crystal film attached to the back surface of the lower polarizer of the display panel, and a peak corresponding to blue light Can be moved in the long wavelength direction. By thus shifting the wavelength of the peak corresponding to the blue light, the blue color coordinate can also be changed.

The reflection type liquid crystal film according to the present embodiment has the peak of the center wavelength of the reflected light of 430 nm and the half width of the peak of 42 nm so that the width of the wavelength of the reflected light is narrow, As shown in Fig.

Specifically, when the width of the peak of the reflected light wavelength is wide, the width of the reflected light having the wavelength shifted in the direction of the long wavelength after recycling is also wide, so that the reflected light with the wavelength shifted in the long wavelength direction is only the wavelength corresponding to the blue wavelength However, it can include wavelengths corresponding to wavelengths of different colors. In this case, since a wavelength corresponding to a color other than blue light is incident on the display panel, the color reproduction rate may decrease. That is, since the width of the wavelength of the reflected light of the reflection type liquid crystal film according to this embodiment is narrow, the color reproduction ratio of the display panel can be improved.

This configuration will be described with reference to FIG. 5 as follows. 5 is a graph showing the blue color coordinates of the display device according to the comparative example, the color coordinates of the DCI-P3 blue standard, and the blue color coordinates of the display device according to the present embodiment. Here, the display device according to the comparative example has the same configuration as the display device according to the comparative example described above in Fig.

Referring to FIG. 5, the display device according to the present embodiment includes the anti-reflection liquid crystal film, and can be moved by (-0.01, 0.03) in the blue color coordinate system on the CIE 1976 color coordinate system according to the comparative example. Thus, by shifting the blue color coordinate of the display device according to this embodiment by (-0.01, 0.03) from the blue color coordinate of the display device according to the comparative example, the color coordinates (0.175, 0.158). ≪ / RTI >

At this time, the blue color coordinate of the display device according to the present embodiment has an effect of improving the overlapping area with the DCI-P3 blue standard by 3% as compared with the blue color coordinate of the display device according to the comparative example. In other words, the blue color coordinate of the display device according to the present embodiment increases as compared with the blue color coordinate of the display device according to the comparative example, thereby increasing the overlapped area with the DCI-P3 blue standard, The color reproduction ratio of the display device can be increased.

Next, a display device according to the second embodiment will be described with reference to FIG. 6 as follows. 6 is a diagram showing a display device according to the second embodiment. The display device according to the second embodiment may include the same components as the display device according to the first embodiment described above. A description overlapping with the display device according to the first embodiment described above can be omitted. The same components have the same reference numerals.

Referring to FIG. 6, the display apparatus according to the second embodiment includes a display panel 500 and a backlight unit 300 disposed on the back surface of the display panel 100. The backlight unit 300 may include a semi-use liquid crystal film 350. The anti-use liquid crystal film 350 may be attached on the plurality of optical sheets 230. At this time, the light generated from the light source assembly 210 can be incident on the semi-use liquid crystal film 350 through the light guide plate 220 and the plurality of optical sheets 230.

Specifically, the anti-use liquid crystal film 350 can be attached on the upper prism sheet 233. [ However, the present embodiment is not limited thereto, and when the plurality of optical sheets 230 include a protective sheet disposed on the upper prism sheet 233, the anti-use liquid crystal film 350 is attached on the protective sheet . That is, it is sufficient that the counter-use liquid crystal film 350 according to the present embodiment is attached to an optical sheet positioned closest to the display panel 100 among the plurality of optical sheets 230.

As described above, light transmitted through or passed through the semi-use liquid crystal film 350 through the light guide plate 220 and the plurality of optical sheets 230 can be incident on the display panel 100. The light that has passed through the reflective liquid crystal film 350 according to the second embodiment and is incident on the display panel 500 can be converted into light including a clear blue wavelength, The light including a clear blue wavelength can be incident on the light receiving element.

In addition, the position of the anti-reflection liquid crystal film 350 is not limited to this, and may be located as shown in FIG. 7 is a view showing a display device according to the third embodiment. The display device according to the third embodiment may include the same components as the display device according to the above-described embodiments. A description overlapping with the display device according to the above-described embodiments may be omitted. The same components have the same reference numerals.

Referring to FIG. 7, the display apparatus according to the third embodiment includes a display panel 500 and a backlight unit 400 disposed on the back surface of the display panel 100. In addition, the backlight unit 400 may include a semi-use liquid crystal film 450. The semi-use liquid crystal film 450 may be positioned between the light source assembly 211 and the light guide plate 220. At this time, the light generated from the light source assembly 211 can be incident on the semi-use liquid crystal film 450.

Here, the semi-use liquid crystal film 450 can reflect and transmit a part of light having a center wavelength peak of 430 nm and a half-width of 42 nm among light generated from the light source assembly 211. At this time, the light reflected by the semi-use liquid crystal film 450 can be reflected by the reflection plate 203 provided inside the light source housing 202 and can be transmitted through the semi-use liquid crystal film 450. The reflection plate 203 provided inside the light source housing 202 may be provided in the entire or a part of the light source housing 202 in which the light source assembly 201 is not disposed.

As described above, the light transmitted through the semi-use liquid crystal film 450 can be incident on the display panel 100 through the light guide plate 220 and the plurality of optical sheets 230. That is, the light before being incident on the light guide plate 220 through the anti-use liquid crystal film 450 according to the third embodiment can be converted into light including a clear blue wavelength, A light including a bright blue wavelength can be incident on the light emitting device.

As described above, the reflective liquid crystal film according to the present embodiments can be positioned at various positions in the display device, and can reflect and transmit light of a specific wavelength. Here, the light reflected by the semi-use liquid crystal film can bring about a luminance improvement effect of the display device through the recycling phenomenon in which retroreflection occurs continuously, and the color reproduction rate of a color corresponding to a specific wavelength can be increased.

In addition, when the semi-use liquid crystal film according to the present embodiments is used, there is an effect that the light absorption band can be adjusted without further developing a light absorbing material.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

100: display panel
110: cell
120: Lower polarizer plate
130: Upper polarizer
200: Backlight unit
210: Light source assembly
220: light guide plate
230: a plurality of optical sheets
250: Half-used liquid crystal film

Claims (12)

And at least one cholesteric liquid crystal layer containing a plurality of liquid crystal molecules,
And the peak wavelength of the reflected light is 430 nm and the half width of the peak is 42 nm.
The method according to claim 1,
And the pitch of the liquid crystal molecules is 275 nm to 280 nm.
The method according to claim 1,
Wherein the refractive index of the liquid crystal molecules is 1.53 to 1.56.
The method according to claim 1,
Wherein the cholesteric liquid crystal layer comprises the same kind of cholesteric liquid crystal molecules.
Display panel;
A backlight unit disposed on a back surface of the display panel, the backlight unit including a light source assembly; And
And at least one cholesteric liquid crystal layer including a plurality of liquid crystal molecules and having a center wavelength peak of 430 nm and a half width of 42 nm, And a reflection type liquid crystal film.
6. The method of claim 5,
And the pitch of the liquid crystal molecules is 275 nm to 280 nm.
6. The method of claim 5,
And the refractive index of the liquid crystal molecules is 1.53 to 1.56.
6. The method of claim 5,
Wherein the cholesteric liquid crystal layer comprises cholesteric liquid crystal molecules of the same kind.
6. The method of claim 5,
Wherein the display panel includes a lower substrate, an upper substrate, and a liquid crystal layer, an upper polarizer disposed above the cell, and a lower polarizer disposed below the cell,
Wherein the reflection type liquid crystal film is bonded to the back surface of the lower polarizer.
6. The method of claim 5,
Wherein the backlight unit includes a plurality of optical sheets disposed on the light guide plate and the light guide plate,
Wherein the reflection type liquid crystal film is disposed on the plurality of optical sheets.
6. The method of claim 5,
Wherein the backlight unit includes a light guide plate and a light source assembly disposed on at least one side of the light guide plate,
Wherein the reflection type liquid crystal film is disposed between the light guide plate and the light source assembly.
12. The method of claim 11,
The light source assembly includes a light source housing having a light source assembly and a light source assembly mounted thereon,
Wherein the reflector is provided in a part or the entire area of the inside of the light source housing where the light source assembly is not disposed.

Images