KR20220007003A - Helical photonic crystal based high-performace color device - Google Patents

Abstract

In accordance with one embodiment of the present invention, a helical photonic crystal-based high-performance color element includes: a backlight part including a light source; an optical improvement part located in an upper part of the backlight part and including a plurality of helical photonic crystal patterns for selectively reflecting or selectively transmitting light of a specific wavelength band outputted from the light source; and a color embodying part located in an upper part of the optical improvement part and including a plurality of color embodying patterns having color spectra corresponding to the plurality of helical photonic crystal patterns respectively. In accordance with an embodiment, color element technology can be applied to commercialized light-emitting type and light-absorption type displays. When the technology is applied to the light-emitting type display, a part of the light heading toward the light source is reflected due to the light emission of a quantum dot, which can lead to an improvement in the light extraction efficiency of the color element. When the technology is applied to the light-absorption type display, the helical photonic crystal patterns selectively transmit the light outputted from the light source and reduce light of remaining wavelength bands, which can lead to an improvement in the color purity of the color element.

Description

HELICAL PHOTONIC CRYSTAL BASED HIGH-PERFORMACE COLOR DEVICE

The present invention relates to a spiral photonic crystal-based high-performance color device, and more particularly, to a color device using a helical photonics crystal having a property of selectively transmitting or reflecting unpolarized incident light in a specific wavelength band. The present invention relates to a color device having a structure capable of improving light extraction efficiency by reflecting a portion of incident light to an output unit or selectively transmitting a portion of incident light according to a driving type of the device.

Light extraction efficiency and color reproducibility are important criteria for determining the performance of next-generation displays, and are indicators of technologies that express natural images through displays. The light extraction efficiency represents the intensity of light actually output to the outside of the screen compared to the amount of light emitted from the light source, and color reproducibility is an index directly related to the color purity of the three primary colors (red, green, and blue). Commercially available displays can be classified into light-emitting or absorption-type displays according to the light emission method of a specific wavelength region inside the color realization film, but each has limitations in light extraction efficiency and color reproducibility.

In the case of a light-emitting display, a specific color is expressed using a material that can emit light by itself, such as a quantum dot, by light or electricity, and it has a higher color purity than an organic light-emitting diode and is characterized by being able to express a wide color gamut. In the case of a photo-luminescence quantum dot-based liquid crystal display, which is a typical form, a quantum dot film in which quantum dots having different emission color gamuts are randomly distributed is combined with a light source and used as a backlight. A separate color filter is required. Due to such a color filter, light transmittance loss is large, and due to the light emission characteristics of quantum dots, light is emitted in all directions. There is a low limit.

In the case of an absorptive display, a color realization film is used to selectively transmit light output from a light source only in a specific wavelength band and absorb light in the remaining wavelength band to realize color. Typically, a white organic light emitting diode (White OLED)-based absorption type color display has an advantage in that it has a lower driving voltage and a higher contrast ratio compared to a conventional liquid crystal-based display. However, in the case of an absorption type color filter, the full width at half maximum of the wavelength expressing each single color is wide at the level of 100 nm, which is 2-3 times wider than that of a quantum dot-based light emitting display. That is, there is a limitation in that high color purity cannot be obtained in the current absorption type display structure.

Republic of Korea Patent Publication No. 10-1989443

Accordingly, the present invention was conceived to solve the above problems, and in a light-emitting color device, a portion of the incident light is generated using a spiral photonic crystal pattern having a characteristic of selectively transmitting or reflecting unpolarized incident light in a specific wavelength band. An object of the present invention is to provide a color device of a new concept capable of improving light efficiency by reflecting it to an output unit and improving color purity by selectively transmitting a part of incident light in an absorption type color device.

A spiral photonic crystal-based color device according to an embodiment of the present invention includes a plurality of spiral photonic crystal patterns positioned above the backlight unit to selectively reflect or selectively transmit light of a specific wavelength band output from the light source a light improvement unit; and a color realizing part positioned above the light improving part and including a plurality of color realizing patterns having respective color spectra corresponding to the plurality of spiral photonic crystal patterns.

In the light emitting color device according to the first embodiment of the present invention, the plurality of color realization patterns are made of a photoluminescent material that emits light by the light incident from the light source, and the light source emits light of the photoluminescent material. It may be configured to output guideable light.

In the first embodiment, the plurality of spiral photonic crystal patterns may be configured to reflect light emitted in the direction of the backlight unit by light emission of the photoluminescent material toward the color realization unit.

In the first embodiment, at least two or more of the plurality of spiral photonic crystal patterns may be configured to reflect or transmit light of different wavelength bands due to different thicknesses or spiral periods of the patterns.

In the first embodiment, each of the plurality of spiral photonic crystal patterns may be configured to reflect light of a specific wavelength band incident from a corresponding color realization pattern located thereon in the direction of the color realization pattern.

In the first embodiment, the light source may induce light emission of the photoluminescent material using at least one of blue light, ultraviolet light, near ultraviolet light, and white light.

In the first embodiment, the light source may have a wavelength capable of independently inducing light emission of the photoluminescent material constituting each color realization pattern.

In the absorptive color device according to the second embodiment of the present invention, the light source is configured to output white light, and the plurality of color realization patterns selectively transmit white light output from the light source only in a specific wavelength band and the rest Color can be realized by absorbing the wavelength band.

In the second embodiment, the plurality of spiral photonic crystal patterns may be configured to selectively transmit only the specific wavelength band among the white light output from the light source and reflect the remaining wavelength band toward the backlight unit.

In the second embodiment, at least two or more of the plurality of spiral photonic crystal patterns may be configured to reflect or transmit light of different wavelength bands due to different thicknesses or spiral periods of the patterns.

In the second embodiment, each of the plurality of spiral photonic crystal patterns may be configured to reflect light of a wavelength band absorbed by a corresponding color realization pattern located thereon toward the backlight unit.

In the second embodiment, the light source may be an organic light emitting diode configured to output white light.

In the second embodiment, at least two of the plurality of color realization patterns may have different thicknesses or different light transmission wavelength regions.

* In an embodiment of the present invention, the backlight unit further includes a modulation device for controlling the intensity of light output from the light source, and the light improvement unit includes a transparent substrate for supporting the plurality of spiral photonic crystal patterns; and an alignment layer disposed on the transparent substrate and configured to define an initial molecular arrangement of the plurality of spiral photonic crystal patterns.

In an embodiment, the modulation device may be arranged together with the plurality of color realization patterns and the plurality of spiral photonic crystal patterns to independently control the intensity of light for each pixel.

In an embodiment, the plurality of spiral photonic crystal patterns may be configured to reflect a polarization component of the incident light opposite to a wavelength band and spiral property of the incident light determined according to the spiral period of each pattern.

In one embodiment, the plurality of spiral photonic crystal patterns may have a cross section of a polygonal shape or a closed figure composed of curves and straight lines when viewed from a direction perpendicular to the surface of the transparent substrate.

In an embodiment, the internal molecular alignment of each of the plurality of spiral photonic crystal patterns may form a spiral shape in a direction perpendicular to the transparent substrate.

In an embodiment, the plurality of spiral photonic crystal patterns may be manufactured by a solution process.

A color device according to an embodiment of the present invention includes a light improving part positioned between a light source and a color realizing part and formed with a plurality of spiral photonic crystal patterns for selectively reflecting or transmitting light of a specific wavelength band. The light improving unit may be designed to improve light efficiency or color purity according to a driving method of a color device and a display.

When applied to a light-emitting color device, the spiral photonic crystal pattern included in the light improvement unit reflects a part of the light emitted toward the light source from the color realization pattern having photoluminescence characteristics toward the output unit, thereby improving the luminance and light extraction efficiency of the color device. can be improved When applied to an absorptive color device, the spiral photonic crystal pattern selectively transmits light in a specific wavelength band before the light output from the light source is incident on the color realization pattern and reduces the light in the remaining wavelength band, thereby improving the color purity of the color device. can do it

As described above, the structure of the color device according to the embodiment can be applied to a commercially available representative display driving type, that is, an absorption type and a light emitting display structure, and display performance by improving light extraction efficiency or color purity according to each driving type can be greatly improved.

1 is a diagram showing the structure of a spiral photonic crystal-based color device according to an embodiment of the present invention.
2A to 2C show light reflectance according to the thickness of a spiral photonic crystal pattern designed to selectively reflect light of wavelength bands corresponding to red (R), green (G), and blue (B), respectively.
3A to 3C are graphs calculated through simulation of light transmittance for each wavelength of spiral photonic crystal patterns designed to improve color purity in wavelength bands corresponding to red (R), green (G), and blue (B).
4 is a view for explaining the operation principle of a spiral photonic crystal-based light emitting color device according to the first embodiment of the present invention.
FIG. 5A is a graph comparing luminance according to wavelength of a red light-emitting quantum dot pattern pixel of a color display according to an embodiment and a conventional color display.
5B is a graph showing the luminescence degree of a red light-emitting quantum dot pattern pixel for each wavelength according to the intensity of incident light in the color display according to the embodiment.
6 is a view for explaining the operation principle of the spiral photonic crystal-based absorption type color device according to the second embodiment of the present invention.
7A to 7C are graphs comparing R, G, and B color spectra of a spiral photonic crystal-based white organic light emitting diode color display according to an embodiment and a conventional white organic light emitting diode display.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] Reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be implemented in other embodiments without departing from the spirit and scope of the invention.

In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents as those claimed. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects.

In the following description, expressions such as "on" or "on" of a specific component do not indicate an absolute direction (a direction opposite to gravity), but include the meaning of being formed based on a specific component in the manufacturing process. For example, in the case of "B located above A", B may actually be located above A, or B may be formed on A and arranged so as to go below A in the assembly stage may be included.

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

1 is a diagram illustrating a structure of a spiral photonic crystal-based color device according to an exemplary embodiment.

Referring to FIG. 1 , a color device according to an exemplary embodiment includes a backlight unit 01 , a light improving unit 04 positioned above the backlight unit 01 , and a light improving unit 04 positioned above the light improving unit 04 . It includes a color realizing unit 10 .

The backlight unit 01 includes a light source 02 and a modulator 03 for controlling the intensity of light output from the light source 02, and includes a plurality of pixels. The light source 02 and the modulator 03 may be formed of different elements or one single element.

In an embodiment, the light source 02 and the modulator 03 may be a single light emitting diode device. However, this is only an example, and materials and variable mechanisms constituting the light source and the modulator are not limited to the above-described ones. That is, an arbitrary single device or an arbitrary plurality of devices capable of generating light and controlling the intensity of the light is sufficient.

The light source 02 may be configured to output light of an appropriate wavelength according to a driving method of the color element. In the case of a light-emitting type color device, the color realization patterns 11 to 13 are composed of a material (eg, quantum dots) that emits light by itself by the light incident from the light source 02, in which case the light source 02 is the light of the material. It may be composed of a device that outputs light of an appropriate wavelength band capable of inducing light emission, for example, blue light, ultraviolet light, near ultraviolet light, or white light.

In the case of an absorptive color device, the light source 02 may be formed of a device emitting appropriate light such as white light (eg, White OLED, etc.) in order to induce absorption of light in a specific wavelength band of the color realization pattern. In this case, the color realization pattern (eg, color filter) implements color by selectively transmitting white light output from the light source 02 only in a specific wavelength band and absorbing the remaining wavelength band.

The modulator 03 may be aligned with the color realization patterns 11 to 13 and the spiral photonic crystal patterns 07 to 09 to independently control the intensity of light for each pixel.

The light improving unit 04 is a component for improving light extraction efficiency or color purity of a color device by selectively reflecting or transmitting light incident from the outside of the light improving unit 04 using a spiral photonic crystal. According to an embodiment, the light improvement unit 04 includes a transparent substrate 05 , an alignment layer 06 for defining an initial molecular alignment direction of a spiral photonic crystal pattern, and selective reflection or transmission characteristics for light of a specific wavelength band. It is composed of a plurality of spiral photonic crystal patterns 07 to 09 having

The transparent substrate 05 is a part for supporting the entire component, and may be made of glass, quartz, polymer resin (eg, plastic, etc.), or other suitable material.

The spiral photonic crystal alignment layer 06 is formed on the transparent substrate 05 and is used to define the initial molecular alignment direction of the spiral photonic crystal patterns 07 to 09 . The alignment layer 06 may define the initial molecular alignment state of the spiral photonic crystal patterns 07 to 09 in a photo-alignment, rubbing, or other suitable manner. In an embodiment, the alignment layer 06 may be formed of a material that is easy to form a thin film and can define a molecular alignment direction through an additional process, for example, polyimide, silicon oxide (SiO ₂ ), or the like. However, this is an example, and the material and forming process constituting the alignment layer 05 are not limited to those described above.

A plurality of spiral photonic crystal patterns 07 to 09 are formed on the alignment layer 06 . The internal molecular alignment of each of the plurality of spiral photonic crystal patterns has a spiral shape with an axis perpendicular to the transparent substrate, and may have different light reflection characteristics in a visible ray band. For example, the spiral photonic crystal patterns 07 , 08 , and 09 may reflect a circularly polarized light component opposite to handedness among red (R), green (G), and blue (B) wavelengths, respectively.

Each spiral photonic crystal pattern may be formed of one or two or more types of dielectric material, for example, a chiral reactive mesogen. However, this is only an example, and may be composed of any material that reflects light of a specific polarization component of a single wavelength band by forming a spiral shape in the direction perpendicular to the substrate through molecular alignment of the photonic crystal, and is limited to a specific material it is not going to be According to an embodiment, each spiral photonic crystal pattern has a cross section of a polygonal shape or a closed figure composed of curved lines and straight lines when viewed from a direction perpendicular to the surface of the transparent substrate.

In order for the plurality of spiral photonic crystal patterns 07 to 09 to have different light reflection characteristics, the thickness or helical pitch of each pattern may be formed to be different from each other. In an embodiment, the spiral photonic crystal patterns may be formed to have one or more spiral periods in order to exhibit light reflection characteristics in the visible ray band.

The graphs of FIGS. 2A to 2C show that the light reflectance according to the thickness of the spiral photonic crystal pattern designed to selectively reflect light in the wavelength bands corresponding to red (R), green (G), and blue (B) is calculated through simulation. shows the results. Definition of chiral-reactive mesogens having different helical periods. Using the ordinary refractive index (n _o ) and the extraordinary refractive index (n _e ) values, the finite-difference time-domain method (finite-difference time-domain) method: simulation using FDTD) was performed. The light reflectance shown in the graph represents a maximum of about 50% in the R, G, and B wavelength bands, respectively, but this is only an example, and the reflectance and reflection wavelength band of the spiral photonic crystal pattern are not limited to the above, and the configuration of each pattern It can be obtained or modified to a greater extent by appropriate control of materials and processes.

The plurality of spiral photonic crystal patterns 07 to 09 may at least partially transmit incident light. For example, the plurality of spiral photonic crystal patterns may transmit the remaining light except for a circularly polarized component opposite to the spiral of the pattern among incident light. As will be described later, light extraction efficiency or color purity of a color device may be improved by using such selective transmission and absorption characteristics.

3a to 3c show the light transmittance for each wavelength of the light transmittance patterns inside the spiral photonic crystal transmittance layer designed to improve color purity in the wavelength bands corresponding to red (R), green (G), and blue (B), respectively, through simulations. It is a calculated graph. Definition of chiral-reactive mesogens having different helical periods Simulation using a finite-difference time-domain method using ordinary refractive index and extraordinary refractive index values carried out. Although the light transmittance each represents about 50% in each wavelength band, this is an example, and the transmittance of the light transmittance pattern is not limited to the above, and can be obtained larger by appropriately adjusting the constituent materials and processes of the light transmittance pattern. can

The color realizing unit 10 is a component for expressing a color for each pixel using the light output from the light source 02 . According to an embodiment, a passivation layer for preventing damage or contamination of each pattern may be formed on the color realization part. The color realization unit 10 includes a plurality of color realization patterns 11 to 13 expressing different colors, and the color realization patterns 11 to 13 may be made of different materials depending on the driving method of the color device. can

In the case of a light-emitting color device, the color realization patterns 11 to 13 are formed of a photoluminescent material that self-emits by light incident from the light source 02 . For example, each of the plurality of color implementation patterns 11 to 13 may have quantum dots having different sizes and/or materials to implement different light emitting characteristics. According to an embodiment, the quantum dot materials may be made of a material including cadmium-selenide to obtain photoluminescence characteristics in a visible ray band capable of achieving high color purity and luminous efficiency. However, this is exemplary, and may be composed of quantum dots capable of emitting light by light output from a light source or any self-luminous material, and is not limited to a specific material.

As described above, in the light emitting color device according to the embodiment, the light source 02 is configured to output light of a wavelength band capable of inducing light emission of the photoluminescent material. For example, the light source 02 may output blue light, ultraviolet light, near ultraviolet light, white light, or a combination thereof to induce light emission of the photoluminescent material (eg, quantum dot material).

In the case of an absorptive color device, the color realization patterns 11 to 13 function as a color filter, and selectively transmits light incident from the light source 02 only for a specific wavelength band and absorbs the remaining wavelength band to obtain color. implement For example, each color realization pattern absorbs a specific wavelength band of light output from the light source and passing through the light improvement unit, and thus different colors of light, such as red (R), green (G), and blue (B), are emitted. real color of

In order to express different colors as described above, the plurality of color realization patterns 11 to 13 may use dyes absorbing light in different wavelength bands. According to an embodiment, the color realization patterns may be composed of a mixture of a pigment and a photoresist. However, this is exemplary, and may be made of any material capable of modulating light emitted from a light source, and is not limited to a specific material.

In the absorption type color device according to the embodiment, the light source 02 is configured to output appropriate light so that the color realization patterns transmit or absorb light of each unique specific wavelength region, for example, output white light It may be an organic light emitting diode (White OLED) device.

The spiral photonic crystal-based color device according to the embodiments described in the present specification is formed such that unit pixels of red (R), green (G), and blue (B) composed of a spiral photonic crystal pattern and a color realization pattern are periodically arranged. , in another embodiment, the type of the spiral photonic crystal, the reflection wavelength band of each spiral photonic crystal, the color realization method, the arrangement order and/or the arrangement form of each element may be configured differently from those disclosed herein. For example, a spiral photonic crystal-based color device composed of unit pixels of cyan, yellow, and magenta can be constructed, and the structure of the elements can be appropriately changed to suit the field to be applied. may be

Hereinafter, structures and operating principles of a reflective color device and an absorptive color device according to practical embodiments will be described with reference to the drawings.

<First embodiment>

4 is a view for explaining the operation principle of the spiral photonic crystal-based light emitting color device according to the first embodiment.

In the structure of the first embodiment, the color realization patterns 11 to 13 include a photoluminescent material such as quantum dots, and they each absorb the same light because the thickness of the pattern, the size of the quantum dot, or the material are different so that the visible light of a different color is absorbed. is configured to emit light. For example, as illustrated, the light emitting material of the color realization patterns 11 , 12 , and 13 absorbs light and emits red, green, and blue visible light, respectively, to realize three color colors.

The backlight unit 01 includes a light source capable of inducing light emission of the color realization patterns 11 to 13 composed of such quantum dots. For example, light having an appropriate wavelength band for inducing independent light emission of the color realization patterns, such as blue light, ultraviolet light, near ultraviolet light, or white light, may be output.

A plurality of spiral photonic crystal patterns 07 to 09 capable of selectively reflecting or transmitting light are formed between the backlight unit 01 and the color realization patterns 11 to 13 . Each unit pixel is composed of a single color realization pattern and a single spiral photonic crystal pattern formed between a light source, and a specific color can be implemented for each unit pixel.

Referring to FIG. 4 , the light output from the backlight unit 01 passes through the transparent substrate and passes through the spiral photonic crystal patterns 07 to 09 . The passing light is incident on the color realization patterns 11 to 13 formed on each spiral photonic crystal pattern to induce photoluminescence of the quantum dots. Accordingly, the quantum dots emit visible light of a specific wavelength band in all directions, of which the light emitted in the direction of the backlight unit 01 is again directed toward the color realization unit (ie, the display output direction) by the spiral photonic crystal pattern located below. is reflected by To this end, each spiral photonic crystal pattern (eg, 07) is designed to selectively reflect light of a specific wavelength band emitted by a corresponding color realization pattern (eg, 11) located thereon.

According to the configuration of the above embodiment, it is possible to significantly increase the output light amount of the display device by reflecting some of the light emitted from the quantum dots in the direction in which the backlight is located (ie, in the opposite direction to the output) and lost by reflecting in the output direction.

5A is a quantum dot color display having a spiral photonic crystal pattern (w/reflector) and a conventional quantum dot color display (w/o reflector) not having a spiral photonic crystal pattern according to an embodiment, the wavelength of the red light-emitting quantum dot pattern pixel It is a graph showing the luminous intensity according to (intensity of incident light is the same). Near-ultraviolet incident light (wavelength 365 nm) was used for quantum dot emission, and the luminescence degree of the quantum dot pattern was measured using a commercial UV-Vis. Fiber optic pectrometer (Ocean Optics S2000), ambient environment. ) was measured.

As shown in the graph of FIG. 5A , it is measured that the amount of light is about 40% or more higher in the color display of the embodiment having the spiral photonic crystal pattern. In the conventional light emitting color device, some of the light emitted from the color realization pattern (ie, the quantum dot material) is directed in the direction in which the light source is located (ie, the opposite direction of the output unit), and a loss occurs in the total amount of output light. According to the structure of the embodiment, since a portion of the light directed toward the light source is reflected back toward the output unit by the spiral photonic crystal pattern, the total amount of output light increases.

In addition, according to the embodiment, it is possible to adjust the light emission intensity of the quantum dot pattern according to the intensity of light incident from the backlight unit 01 . That is, as will be described later, it is possible to adjust the luminance of the quantum dot pattern by adjusting the intensity of the incident light through the light source and the modulator. Therefore, it is possible to express each gray level of red, green, and blue, and it is possible to implement high-quality color video.

5B is a graph showing the luminescence degree of a red light-emitting quantum dot pattern pixel for each wavelength according to the intensity of incident light in the quantum dot color display having a spiral photonic crystal reflection pattern according to the embodiment. Near-ultraviolet incident light (wavelength 365 nm) was used for quantum dot emission, and the luminescence degree of the quantum dot pattern was measured using a commercial UV-Vis. Fiber optic pectrometer (Ocean Optics S2000), ambient environment. ) was measured. As shown in FIG. 5B , it can be seen that as the intensity of the incident light increases, the luminous intensity of the red light-emitting quantum dots increases. Accordingly, it is possible to express gradation even for the same color, and finally, a color video with high color purity can be realized.

<Second embodiment>

6 is a view for explaining the operation principle of the spiral photonic crystal-based absorption type color device according to the second embodiment.

In the structure of the second embodiment, the backlight unit 01 includes a light source composed of a light emitting device capable of outputting white light, for example, a white organic light emitting diode (White OLED). Color is realized by selectively transmitting white light output from the light source 02 only in a specific wavelength band and absorbing the remaining wavelength band. For example, as shown, the color realization pattern 11 transmits red visible light and absorbs light of the remaining wavelength band, and the color realization pattern 12 transmits green visible light and absorbs light of the remaining wavelength band, and the color realization pattern (13) implements three color colors by transmitting visible blue light and absorbing light in the remaining wavelength band.

A plurality of spiral photonic crystal patterns 07 to 09 capable of selectively reflecting or transmitting light are formed between the backlight unit 01 and the color realization patterns 11 to 13 . Each unit pixel is composed of a single color realization pattern and a single spiral photonic crystal pattern formed between a light source, and a specific color can be implemented for each unit pixel.

Referring to FIG. 6 , white light output from the backlight unit 01 passes through a transparent substrate and passes through spiral photonic crystal patterns 07 to 09, in which case the spiral photonic crystal pattern is the color of each corresponding color realization pattern, that is, red. It transmits only light corresponding to the wavelength bands of (R), green (G), and blue (B), and selectively reflects light corresponding to cyan (C), magenta (M), and yellow (Y), which are complementary to this. to return to the backlight unit 01 direction.

For example, the spiral photonic crystal pattern 07 corresponds to the color realization pattern 11 for realizing red visible light. In order to realize a higher purity red light, white light output from the light source is selectively transmitted only in a red wavelength band. and the remaining wavelength band is reflected toward the backlight unit. The red light passing through the spiral photonic crystal pattern 07 is irradiated to the color filter to finally realize red light of high color purity. According to this, although the luminance may be slightly reduced compared to the conventional color device according to the selective transmission of the spiral photonic crystal film, it is possible to realize a color with higher color purity.

In this case, the intensity of the light output to the outside of the device may be adjusted according to the intensity of the light output from the backlight unit 01 as in the first embodiment. As a result, it is possible to express each gray level of red, green, and blue, and it is possible to implement color video with high color purity.

7A to 7C are graphs comparing R, G, and B color spectra of a spiral photonic crystal-based white organic light emitting diode color display according to an embodiment and a conventional white organic light emitting diode display through simulation.

Referring to FIG. 7A , a white organic light emitting diode color display (WOLED-Ch(R)-CF(R)) having a spiral photonic crystal pattern has a peak wavelength of 620 nm and a conventional white organic light emitting diode display (WOLED-CF(R)) )), it can be seen that the line width is narrowed. This means that higher color purity can be achieved by reducing unnecessary wavelength ranges other than the desired color (red).

Similarly, FIG. 7b has a peak wavelength of 540 nm, indicating that high purity green is implemented compared to the conventional display, and FIG. 7c also has a peak wavelength of 460 nm, which is narrower than the conventional display to realize high purity blue. indicates.

The spiral photonic crystal-based color device technology described above can be applied to commercially available light-emitting and absorption-type displays in different forms. When applied to a light emitting display, the light extraction efficiency of the color device can be improved by reflecting a portion of the light directed to the light source by the light emission of the quantum dots back toward the output unit. When applied to an absorptive display, the color purity of a color device can be improved by selectively transmitting light output from a light source and reducing light in the remaining wavelength bands in the spiral photonic crystal pattern.

As described above, the structure of the color device according to the embodiment can be applied to both absorption-type displays and light-emitting displays, which are commercial typical display types, and improves display performance by improving light extraction efficiency or color purity according to each driving type. can be greatly improved.

Although the above-described invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary and those of ordinary skill in the art will understand that various modifications and variations of the embodiments are possible therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Accordingly, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

01: backlight unit
02: light source
03: modulator
04: light improvement part
05: transparent substrate
06: alignment layer
07, 08, 09: spiral photonic crystal pattern
10: color realization part
11, 12, 13: color realization pattern

Claims (18)

a backlight unit including a light source and a modulator for controlling the intensity of light output from the light source;
a light improvement unit positioned above the backlight unit and including a plurality of spiral photonic crystal patterns for selectively reflecting or selectively transmitting light of a specific wavelength band output from the light source; and
A color realizing part positioned above the light improving part and including a plurality of color realizing patterns having respective color spectra corresponding to the plurality of spiral photonic crystal patterns,
wherein the modulation device is arranged with the plurality of color realization patterns and the plurality of spiral photonic crystal patterns to independently control the intensity of light for each pixel, a spiral photonic crystal-based color device.
According to claim 1,
When the plurality of color realization patterns are made of a photoluminescent material that emits light by the light incident from the light source,
The plurality of color realization patterns are composed of a photoluminescent material that emits light by the light incident from the light source,
wherein the light source is configured to output light capable of inducing emission of the photoluminescent material.
3. The method of claim 2,
The spiral photonic crystal-based color device, characterized in that the plurality of spiral photonic crystal patterns are configured to increase the amount of output light by reflecting light emitted in the direction of the backlight unit by light emission of the photoluminescent material toward the color realizing unit. .
4. The method of claim 3,
At least two or more of the plurality of spiral photonic crystal patterns are configured to reflect or transmit light of different wavelength bands due to different thicknesses or spiral periods of the patterns, a spiral photonic crystal-based color device.
5. The method of claim 4,
The plurality of spiral photonic crystal patterns is a spiral photonic crystal-based color device, characterized in that it is configured to reflect light of a specific wavelength band incident from a corresponding color realization pattern located thereon in the direction of the color realization pattern.
3. The method of claim 2,
The light source uses at least one of blue light, ultraviolet light, near ultraviolet light and white light to induce light emission of the photoluminescent material, a spiral photonic crystal based color device.
7. The method of claim 6,
The light source is a spiral photonic crystal-based color device, characterized in that it has a wavelength capable of independently inducing light emission of the photoluminescent material constituting each color realization pattern.
According to claim 1,
When the plurality of color realization patterns are composed of a color filter that realizes color by absorbing light output from the light source for a specific wavelength band,
The light source is configured to output white light,
The plurality of color realization patterns selectively transmit white light output from the light source in only a specific wavelength band and absorb the remaining wavelength band to realize color, a spiral photonic crystal-based color device.
9. The method of claim 8,
The spiral photonic crystal-based color device, characterized in that the plurality of spiral photonic crystal patterns are configured to selectively transmit only the specific wavelength band among the white light output from the light source and reflect the remaining wavelength band toward the backlight unit.
10. The method of claim 9,
At least two or more of the plurality of spiral photonic crystal patterns have different thicknesses or spiral periods and reflect light of different wavelength bands, thereby increasing the color purity of each color realization part. based color element.
11. The method of claim 10,
Each of the plurality of spiral photonic crystal patterns is a spiral photonic crystal-based color device, characterized in that it is configured to reflect light in a wavelength band absorbed by a corresponding color realization pattern located thereon in the direction of the backlight unit.
9. The method of claim 8,
The light source is a spiral photonic crystal based color device, characterized in that the organic light emitting diode is configured to output white light.
13. The method of claim 12,
At least two or more of the plurality of color realization patterns, a spiral photonic crystal-based color device, characterized in that the thickness or the light transmission wavelength region of the pattern is different from each other.
According to claim 1,
The light improvement unit further comprises a transparent substrate for supporting the plurality of spiral photonic crystal patterns, and an alignment layer positioned on the transparent substrate to define an initial molecular arrangement of the plurality of spiral photonic crystal patterns. , a spiral photonic crystal-based color device.
15. The method of claim 14,
The plurality of spiral photonic crystal patterns is a spiral photonic crystal-based color device, characterized in that it is configured to reflect a wavelength band of the incident light determined according to the spiral period of each pattern and a polarization component of the incident light opposite to the spiral.
15. The method of claim 14,
The plurality of spiral photonic crystal patterns, when viewed from a direction perpendicular to the surface of the transparent substrate, characterized in that it has a cross section of a polygonal shape or a closed figure composed of curves and straight lines, a spiral photonic crystal-based color device.
15. The method of claim 14,
The internal molecular alignment of each of the plurality of spiral photonic crystal patterns is a spiral photonic crystal-based color device, characterized in that it forms a spiral shape with an axis perpendicular to the transparent substrate.
15. The method of claim 14,
The plurality of spiral photonic crystal patterns is characterized in that manufactured by a solution process, a spiral photonic crystal-based color device.

Images