KR101781554B1 - Reflective color filter and apparatus and method for color display employing the same - Google Patents

Abstract

A reflection type color filter, a reflection type color display device using the same, and a display method thereof are disclosed. The disclosed reflection type color filter has first and second photonic crystal regions including a variable photonic crystal which reflects light of a selected wavelength band from external light and whose optical band gap corresponding to a frequency bandwidth reflecting the light by the stimulus is controlled do. The control unit controls the optical bandgap of the variable photonic crystal in the first and second photonic crystal regions by independently imparting a stimulus to the first and second photonic crystal regions, thereby controlling the combination of the selective wavelength bands reflected in the first and second photonic crystal regions So that a desired color can be expressed by the color.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective color filter, a reflective color filter, and a reflective color filter.

And more particularly, to a reflection type color filter using a variable photonic crystal, a reflection type display device using the same, and a display method thereof.

A conventional color display device displays a color by dividing a fixed three-color filter into areas and transmitting or reflecting light thereon.

In such a conventional color display device, there is a large loss of light caused by passing through the absorption type color filter of the principle that only the desired color is passed and the rest is absorbed. In addition, since the absorption type color filter is used in an area-divided manner, when a primary color or a color close thereto is displayed, the light passing through the remaining color region is completely blocked, resulting in a large color loss.

When the absorption type color filter is used in a reflection type color display device, the loss ratio lost in the color filter is squared due to the nature of the reflection type, and it is difficult to further display the bright color.

As an alternative to this, a color filter utilizing a photonic crystal having a property of completely reflecting the color corresponding to the photonic bandgap and transmitting the rest is being studied. The color primary color represented by the photonic crystal boasts a shiny and brilliant color that can not be expressed by conventional color filters. However, by using a photonic crystal color filter, it is possible to solve the problem that the light loss of the reflection type display device in the absorption type color filter becomes a square. However, in order to display all the color areas on a color coordinate system that can be perceived by human beings, Therefore, the problem of color loss due to use of the color filter in an area division remains unresolved.

A reflection type color filter using an improved variable photonic crystal to reduce color loss due to area division, a reflection type display device using the same, and a display method thereof are provided.

A reflection type color filter according to an exemplary embodiment of the present invention includes a variable optical crystal that includes a variable photonic crystal that reflects light of a selected wavelength band from external light and adjusts a photonic band gap corresponding to a frequency bandwidth that reflects light by stimulation, A second photonic crystal region; The first photonic crystal region and the second photonic crystal region are provided with a stimulus independently to adjust the photonic bandgap of the variable photonic crystal in the first and second photonic crystal regions to produce a combination of selective wavelength bands reflected in the first and second photonic crystal regions And a control unit for causing the display unit to display a desired color.

And an absorption plate under the first and second photonic crystal regions.

Each of the first and second photonic crystal regions may include a variable photonic crystal in which at least one of shape, volume, and effective refractive index is changed by electrical or mechanical conversion to change the center frequency of the photonic band gap.

The first and second photonic crystal regions may be arranged in a horizontal direction.

And a photonic crystal panel having the first and second photonic crystal regions formed in regions corresponding to one pixel of the display device and having a two-dimensional array of the first and second photonic crystal region pairs.

The first and second photonic crystal regions may have an overlapping structure.

A first photonic crystal panel having the first photonic crystal region and a second photonic crystal panel having the second photonic crystal region for each region corresponding to one pixel of the display device for each region corresponding to one pixel of the display device, And the second photonic crystal panel may be provided so as to form an overlapping structure.

A reflection type color display device according to an embodiment of the present invention includes a variable optical crystal that includes a variable photonic crystal that reflects light of a selected wavelength band from external light and that adjusts a photonic band gap corresponding to a frequency bandwidth that reflects light by stimulation, And a second photonic crystal region, wherein the first photonic crystal region and the second photonic crystal region are independently stimulated to adjust the optical bandgap of the variable photonic crystal in the first and second photonic crystal regions, A reflection type color filter having a two-dimensional array of regions including the first and second photonic crystal regions corresponding to one pixel, and a control unit for causing a desired color to be expressed by a combination of the selected wavelength bands. And a shutter that variably changes the transmittance of light and variably adjusts the amount of light incident on the first and second photonic crystal regions.

Wherein the first and second photonic crystal regions are arranged in a horizontal direction and the first and second photonic crystal regions are formed for each region corresponding to one pixel to have a two-dimensional array of the first and second photonic crystal region pairs .

Wherein the photonic crystal panel includes a first photonic crystal panel having the first photonic crystal region and a second photonic crystal panel having the second photonic crystal region for each region corresponding to one pixel for each region corresponding to one pixel, And a second shutter positioned between the first and second photonic crystal panels, wherein the first shutter and the second shutter are disposed such that the two photonic crystal panels form an overlapping structure, And the second photonic crystal panel.

The reflection type color filter may further include an absorption plate under the first and second photonic crystal regions.

Each of the first and second photonic crystal regions may include a variable photonic crystal in which at least one of shape, volume, and effective refractive index is changed by electrical or mechanical conversion to change the center frequency of the photonic band gap.

In order to display a color image using the reflective color display device according to an embodiment of the present invention, the first and second photonic crystal regions of the reflective color filter are provided with stimuli independently of each other, Adjusting a photonic bandgap of the variable photonic crystal of the first and second photonic crystal regions; And driving the shutter to variably adjust the amount of light incident on the first and second photonic crystal regions to display a desired color image at a desired brightness.

According to the reflective color filter, the reflective display device and the display method using the reflective color filter according to the embodiment of the present invention, the brightness of the primary color can be improved at least twice as compared with the conventional three color partitioning method, It can also be greatly improved. In addition, by using color filters capable of changing colors, the brightness of white can be greatly improved.

FIG. 1 schematically shows the structure of a reflection type color filter according to an embodiment of the present invention and a reflection type color display device using the same.
Fig. 2 schematically shows a color coordinate system. Fig. 2 shows an example of possible combinations of color coordinates indicating white color.
Fig. 3 shows a simplified color coordinate model as a semicircular model without losing generality.
FIG. 4 is a view for explaining a color display method of a color area which can be expressed by a maximum brightness and an area which is not.
FIG. 5 schematically shows a reflection type color filter of a superposed structure according to another embodiment of the present invention and a reflection type color display device using the same.
FIG. 6 shows an existing structure in which a pixel area is divided into three and a color is displayed by a three-primary-color filter.
FIG. 7 shows a structure in which one pixel area is divided into two areas in which color display of the area-divided variable pixels can be performed corresponding to the embodiment of FIG.
FIG. 8 shows a structure in which two variable pixels, in which color display of a superposition type variable pixel can be performed, are superimposed, corresponding to the embodiment of FIG.
FIG. 9 is a graph schematically illustrating the brightness characteristics of the color display according to the color display systems of FIGS. 6 to 8. FIG.

The reflection type color filter and the reflection type color display device using the same according to the embodiment of the present invention can be applied to a variable color modulation photonic crystal (hereinafter referred to as " variable photonic crystal ") capable of changing the optical band gap region in real time by electrical or mechanical stimulation . According to the reflective color filter and the reflective color display device using the variable color filter according to the embodiment of the present invention described below, the display color is changed along the curve close to the edge of the color coordinate corresponding to the full primary color using the variable photonic crystal, Any point on the display color curve can be displayed analogously through the circuit.

In order to display all the colors perceivable by humans on the color coordinate system including white and black, a straight line passing through the desired color coordinate is represented by the display color curve It is possible to represent an arbitrary point on a color coordinate system by a combination of two specific colors. Unlike the conventional three primary color display method in which fixed three primary colors are determined, if the color display method is used, any color on a color coordinate can be displayed with only two colors, so that light loss in a color filter according to three area division can be greatly reduced. Since there are various methods of representing the color coordinates with two colors, it is possible to configure the driving circuit so as to select an appropriate driving mechanism and a color display algorithm and to select a color display combination representing the maximum brightness among them.

According to the reflection type color display apparatus according to the embodiment of the present invention, the absorption color filter can exhibit clearer and brighter primary colors and composite colors as compared with the use of the absorption color filters, It is possible not only to display shiny and brilliant colors that can not be expressed by a light source but also to contribute to the development of a color display device that consumes less power and simplifies its structure by using external light as a light source.

FIG. 1 schematically shows the structure of a reflection type color filter according to an embodiment of the present invention and a reflection type color display device using the same.

Referring to FIG. 1, the reflection type color display device includes a reflection type color filter 1 and a shutter 30 for variably controlling the amount of light incident on the reflection type color filter 1. The reflection type color filter includes a photonic crystal panel 10 having first and second pairs of photonic crystal regions 11 and 13 for reflecting light of a selected wavelength band from external light, And a control unit 50 for applying the electrical or mechanical stimulus to the second photonic crystal regions 11 and 13 to adjust the photonic bandgap of the photonic crystal.

Since the reflection type color filter 1 totally reflects light of a selected wavelength band in accordance with the basic principle thereof and transmits the remaining light to the bottom, it is not necessary to use a reflection mirror necessary when using the absorption type color filter, A black absorbing plate 20 blocking the back reflection can be added underneath. The absorption plate 20 may be included in a component of the reflection type color filter 1 or may be included as a component of a color type reflective display device.

The shutter 30 may be provided to vary the amount of light incident on each of the first and second photonic crystal regions 11 and 13 of the photonic crystal panel 10 by varying the transmittance of light. That is, the shutter 30 may include a pair of first and second shutter areas 31 and 33, respectively, for adjusting the amount of light incident on the first and second photonic crystal areas 11 and 13, respectively.

1 shows only the structure of the reflective color filter 1 and the shutter 30 in the region corresponding to one pixel of the reflective color display device for the sake of clarity. In the photonic crystal panel 10, The first and second photonic crystal regions 11 and 13 are arranged in parallel to each other. When applied to a reflection type color display device, the reflection type color filter 1 is provided with two The photonic crystal panel 10 is provided in an array such that the pairs of the first and second photonic crystal regions 11 and 13 form a two-dimensional array. That is, in the reflection type color filter 1, the photonic crystal panel 10 is arranged such that the first and second photonic crystal regions 11 and 13 are located in the regions corresponding to one pixel of the reflection type color display device, Dimensional array of pairs of two photonic crystal regions 11 (13). The shutter 30 may be provided for each pixel so as to adjust the amount of light incident on each of the first and second photonic crystal regions 11 and 13 located in each pixel. That is, the shutter 30 has a two-dimensional array of pairs of first and second shutter areas 31, 33 corresponding to the two-dimensional array of the first and second photonic crystal regions 11, 13 pairs .

In FIG. 1, the first and second photonic crystal regions 11 and 13 are arranged in a horizontal direction. The first and second photonic crystal regions 11 and 13 are formed in the same manner as in FIG. 5 , And may be arranged so as to form an overlapping structure.

In the photonic crystal panel 10, each of the first and second photonic crystal regions 11 and 13 may include a variable photonic crystal in which a photonic band gap corresponding to a frequency bandwidth for reflecting light by a stimulus is controlled, And may include a tunable photonic crystal.

The variable photonic crystal is capable of adjusting a photonic bandgap corresponding to a frequency bandwidth that reflects light in a photonic crystal due to changes in shape, volume, or effective refractive index due to external electrical or mechanical changes.

This variable photonic crystal can change the photonic band gap region from the infrared region to the ultraviolet region according to the external stimulus. In addition, it is also possible to implement a color filter which becomes transparent when the photonic bandgap region of the variable photonic crystal is transmitted to the ultraviolet or infrared region.

The variable photonic crystal applied to the first and second photonic crystal regions 11 and 13 may be formed in a volatile environment by infiltration of an electrolyte by a reversible oxidation-reduction reaction induced by voltage, for example, The nanoparticles of the high refractive index dielectric may be photonic crystals distributed in crystalline form.

The control unit 50 controls the first and second photonic crystal regions 11 and 13 of the photonic crystal panel 10 so that the first and second photonic crystal regions 11 and 13 have irregularities, And the desired color is expressed by a combination of the selective wavelengths reflected by the first and second photonic crystal regions 11 and 13 by adjusting the photonic bandgap.

The shutter 30 and the photonic crystal panel 10 are electrically connected to each other so that the shutter 30 and the photonic crystal panel 10 can be controlled by the control unit 50. [ 41b, 41c (43a, 43b, 43c) may be provided between the shutter 30 and the photonic crystal panel 10 and below the photonic crystal panel 10. [ The electrodes 41a, 41b and 41c 43a, 43b and 43c are connected to the first and second shutter regions 31 and 33 of the shutter 30 and the first and second shutter regions 31 and 33 of the photonic crystal panel 10, And may be provided corresponding to the arrangement of the pairs of the second photonic crystal regions 11 and 13. 1, the electrodes 41b and 43b positioned between the shutter 30 and the photonic crystal panel 10 are commonly used. The electrodes required at the lower portion of the shutter 30 and the electrodes The electrode required above may be provided separately.

According to the reflective color display device as described above, the reflective color filter 1 having one photonic crystal panel 10 and the one shutter 30 are provided, and the photonic crystal panel 10 and the shutter 30 Two photonic crystal regions and two shutter regions correspond to one pixel.

According to the reflection type color display device described above, first and second photonic crystal regions 11 and 13 of the photonic crystal panel 10 constituting the reflection type color filter 1 are first It stimulates independently. Accordingly, the optical bandgap of the variable photonic crystal of the first and second photonic crystal regions 11 and 13 is adjusted to be able to reflect only the light of a desired wavelength. By controlling the amount of light incident on the first and second photonic crystal regions 11 and 13 by driving the shutter 30 in such a controlled state, an image of a desired color can be displayed with a desired brightness .

Hereinafter, the principle that a desired color can be realized by the photonic crystal panel 10 having the first and second photonic crystal regions 11 and 13 which are independently controlled for each pixel as described above will be described.

Fig. 2 schematically shows a color coordinate system. Fig. 2 shows an example of possible combinations of color coordinates indicating white color. In Fig. 2, R, G, and B represent red, green, and blue, respectively, which are three primary colors.

Referring to FIG. 2, in order to represent an arbitrary point on a color coordinate by a specific combination of colors, two primary colors corresponding to the vertices of a line segment, for example, A1 and A2, B1 and B2 are required. However, when colors are displayed by combining only two colors, the selection of the primary colors may be various.

Therefore, in contrast to the linear combination which is uniquely determined to represent an arbitrary color coordinate in the existing three-primary-color model, it is necessary to select an optimum among the two-color linear combinations possible. In order to obtain more favorable display characteristics, the following two can be considered.

First, although various combinations of primary colors can be used to represent the same color coordinates, the brightness characteristics of each combination are different. Therefore, the brightest combination can be selected.

Second, the color change magnitude of the variable element is proportional to its response speed. Therefore, it can be considered that when moving the display color from one color to another, the movement length of the color coordinate is the shortest, which is advantageous for moving picture display.

Fig. 3 shows a simplified color coordinate model as a semicircular model without losing generality. FIG. 3 shows the color gamut of two color pixels that can represent any internal color coordinates. In the semicircle of FIG. 3, the left end represents the blue (B) limit and the right end represents the red (R) limit. In Fig. 3, a ° and b ° represent any values from the blue (B) limit and the red (R) limit. Here, the two-color pixel means a case in which one pixel is divided into two colors.

A straight line passing through an arbitrary point in a semicircle may have an arbitrary value in a range from the end of the semicircle (blue limit) to the point where the opposite side passes through the end of the other semicircle (red limit) as shown in Fig. 3 .

In this case, the ratio of the length of the left line segment of the color coordinate system to the length of the right line segment in the line segment based on the desired color coordinate decreases monotonically as the left point of the line segment moves from the blue limit to the green limit, and there is only one combination in which the color coordinate is in the center of the line segment .

In the reflection type, since the brightest brightness that the color display element can show with respect to the incident light is fixed by the reflectance, it is necessary to darken the other reflection to adjust the ratio of the intensity of the color in the two color pixels. Therefore, in order to obtain the brightest brightness in the desired color coordinate, it is advantageous that the relative brightness of the two colors is the closest. Therefore, the pixel combination having the brightest brightness in a given color coordinate is represented by a dotted line in Fig.

Therefore, if the desired color coordinate is displayed at the center of a line segment composed of two color pixels in order to obtain the maximum brightness, the color of the two color pixels with respect to the desired color coordinate is uniquely determined. It is possible to make a color display element that shows the brightness of the display.

However, this method does not display the entire color gamut. FIG. 4 is a view for explaining a color display method of a color area which can be expressed by a maximum brightness and an area which is not. In FIG. 4, a darkened area of a large semicircle corresponds to a color area that can be expressed with maximum brightness, and two small semicircles correspond to a color area that can not be represented by maximum brightness.

An area not represented by the center coordinates can be expressed as follows.

That is, if the color coordinate to be represented is in the left four semicircular area (between blue and green) of one semicircle, one of the two color pixels is fixed at the blue limit and only the intensity of the reflection is adjusted, Can be represented by changing only the color without changing the reflectance.

Also, if the color coordinate to be displayed is in the opposite semicircular region (between red and green), one of the color pixels is also fixed at the red limit to control only the intensity of the reflection, and the other changes only the color in the blue and green regions.

When the color region is represented in the above-described manner, the brightness is reduced by a certain amount.

As described above, in order to represent all the color coordinates in the color coordinate area in a linear combination, a relative intensity change between the two primary colors may also be necessary. Since the first and second shutter regions 31 and 33 of the variable shutter 30 for adjusting the intensity of light are located on the first and second photonic crystal elements 11 and 13 constituting the two color pixels, Filter, and reflection type color display device as shown in FIG. 1, all the colors in the color coordinates can be represented by two color pixels.

In the above description, when the first and second photonic crystal devices 11 and 13 constituting one pixel are arranged in the horizontal direction and the reflection type color filter 10 and the shutter 30 are provided in an area division manner Have been illustrated and shown by way of example, but the embodiment of the present invention is not limited thereto. For example, the reflection type color filter and the reflection type color display device using the same according to the embodiment of the present invention may use a characteristic of the photonic crystal that reflects only the light corresponding to the selected optical bandgap region and transmits the remaining light, It is also possible to place the reflection type color filter in an overlapping manner with respect to the incident direction of light.

That is, when a conventional color filter is placed in a superposed state, a color component located on the lower side can not express a composite color that is darker than the above color, so that the overlapped color filter itself must be arranged in a row by arranging different combinations. The structure becomes very complicated and the advantage of the overlap type color filter is largely canceled. However, as in the case of the reflection type color filter according to the embodiment of the present invention, this problem is solved naturally when the color filter is color-varied. Therefore, it is possible to realize a superposition type reflection type color filter and a reflection type color display device using the superposition type reflection type color filter by a simple combination as shown in FIG.

FIG. 5 schematically shows a reflection type color filter of a superposed structure according to another embodiment of the present invention and a reflection type color display device using the same. Here, members having substantially the same or similar functions as those in FIG. 1 are denoted by the same reference numerals, and repetitive description thereof will be omitted.

Referring to FIG. 5, the reflection type color display device includes a reflection type color filter 1 'and a shutter. The reflective color filter 1 'includes first and second superposed photonic crystal panels 10a and 10b and a control unit 50. [ The shutter is disposed between the first and second photonic crystal panels 10a and 10b so as to variably control the amount of light incident on the first and second photonic crystal panels 10a and 10b of the reflection type color filter 1 ' And a second shutter 30b positioned on the side where external light is incident.

5, the first photonic crystal panel 10a and the second photonic crystal panel 10b constituting the reflection type color filter 1 'are arranged in the order of the first photonic crystal region 11 array, the second photonic crystal region 10b, (13) array. The first photonic crystal panel 10a and the second photonic crystal panel 10b form an overlapping structure. The controller 50 controls the optical bandgap of the photonic crystal by applying electrical or mechanical stimulation to the first and second photonic crystal regions 11 and 13 of the first and second photonic crystal panels 10a and 10b.

The first shutter 10a has a first shutter area 31 for variably controlling the amount of light incident on each first photonic crystal area 11 of the first photonic crystal panel 10a by varying the transmittance of light, do. The second shutter 30b has a second shutter area 33 for variably controlling the amount of light incident on the second photonic crystal area 13 of the second photonic crystal panel 10b by varying the light transmittance .

5 shows an example in which the first photonic crystal panel 10a, the first shutter 10a, the second photonic crystal panel 10b, and the second shutter 10b are superimposed in this order. Below the first photonic crystal panel 10a, a black absorption plate 20 may be positioned to block the complementary color transmitted through the first photonic crystal region 11 of the first photonic crystal panel 10a from being reflected upward. As described above, the absorption plate 20 may be included in the component of the reflection type color filter 1 'or may be included as a component of the color type reflective display device.

In the above superposed structure, the first and second photonic crystal regions 11, 13, the first and second shutter regions 31, 33 may have a size corresponding to one pixel, The first photonic crystal region 11, the first shutter region 31, the second photonic crystal region 13, and the second shutter region 33 are overlapped with each other.

5 shows only the structures of the first and second photonic crystal panels 10a, 10b, the first and second shutters 30a, 30b in the region corresponding to one pixel of the reflective color display device for clarity of illustration When the reflective color filter 1 'is applied to a reflective color display device, the first and second photonic crystal regions 11 and 13 correspond to a two-dimensional pixel array of a reflective color display device, The first and second photonic crystal panels 10a and 10b are arranged in an array so as to overlap each other. That is, in the reflection type color filter 1 ', the first photonic crystal panel 10a has the first photonic crystal region 11 so that the first photonic crystal region 11 is positioned for each region corresponding to one pixel of the reflection type color display device, And the second photonic crystal panel 10b may have a two-dimensional array of the second photonic crystal region 13 so that the second photonic crystal region 13 is positioned for each region corresponding to one pixel of the reflective color display device. You can have a dimension array. The first shutter 30a may be provided for each pixel so as to adjust the amount of light incident on the first photonic crystal region 11 corresponding to each pixel, and the second shutter 30b may be provided for each pixel, The second photonic crystal region 13 may be formed to correspond to the first photonic crystal region 13 and the second photonic crystal region 13, respectively. That is, the first shutter 30a may be provided so as to have a two-dimensional array of the first shutter region 31 corresponding to the two-dimensional array of the first photonic crystal region 11, Dimensional array of the second shutter area 33 so as to correspond to the two-dimensional array of the second photonic crystal area 13. [

According to the overlapping structure of the reflection type color filter 1 'and the first and second shutters 30a and 30b, the reflection type color filter 1' according to another embodiment of the present invention substantially comprises one pixel A pair of photonic crystal panels each having one photonic crystal region per pixel are superimposed on one another, and a pair of photonic crystal panels having one photonic crystal region per pixel are superimposed on one another. In the reflection type color display device according to another embodiment of the present invention, In addition, a shutter having one shutter region per pixel is provided on each photonic crystal panel.

The controller 50 controls the first and second photonic crystal regions 11 and 13 by applying magnetic poles independently to the first and second photonic crystal regions 11 and 13 of the first and second photonic crystal panels 10a and 10b, ) 13 by controlling the photonic bandgap of the variable photonic crystal so that a desired color is expressed by a combination of the selective wavelengths reflected by the first and second photonic crystal regions 11 and 13.

The control unit 50 and the first and second shutters 30a and 30b are controlled such that the first and second shutters 30a and 30b and the first and second photonic crystal panels 10a and 10b can be controlled by the control unit 50. [ The second shutter 30b and the second photonic crystal panel 10b so as to electrically connect the first and second photonic crystal panels 30a and 30b and the first and second photonic crystal panels 10a and 10b, The electrodes 41a ', 41b', 41b 'are formed between the second photonic crystal panel 10b and the first shutter 30a, between the first shutter 30a and the first photonic crystal panel 10a and below the first photonic crystal panel 10a, 43a ', 43b', and 43c 'are provided. The electrodes 41a ', 41b', 43a ', 43b', and 43c 'are formed in the first shutter area 31 of the first shutter 30a and the second shutter area 31b of the second shutter 30b, 33, the first photonic crystal region 11 of the first photonic crystal panel 10a, and the second photonic crystal region 13 of the second photonic crystal panel 10b. 5 shows a state in which the first photonic crystal panel 10a and the first shutter 30a, the first shutter 30a and the second photonic crystal panel 10b, and the second photonic crystal panel 10b and the second shutter 30b The electrodes 43b ', 43a', and 41b 'positioned at the lower portion of the first shutter 30a and the electrodes 43b' positioned at the lower portion of the second shutter 30b are used in common. Electrodes, electrodes required on the first photonic crystal panel 10a, and electrodes required on the top and bottom of the second photonic crystal panel 10b may be separately provided.

According to the reflection type color display device as described above, in order to display a color image, first and second photonic crystals of the first and second photonic crystal panels 10a and 10b constituting the reflection type color filter 1 ' The regions 11 and 13 are independently stimulated. Accordingly, the optical bandgap of the variable photonic crystal of the first and second photonic crystal regions 11 and 13 is adjusted to be able to reflect only the light of a desired wavelength. When the amount of light incident on the first and second photonic crystal regions 11 and 13 is variably controlled by driving the first and second shutters 30a and 30b in the thus adjusted state, Can be displayed with desired brightness.

According to the reflection type color filter and the reflection type color display device according to the embodiments of the present invention described above, the brightness can be greatly improved as compared with the conventional three primary color pixel color display method.

FIG. 6 shows an existing structure in which a pixel area is divided into three and a color is displayed by a three-primary-color filter. FIG. 7 shows a structure in which one pixel area is divided into two areas in which color display of the area-divided variable pixels can be performed corresponding to the embodiment of FIG. FIG. 8 shows a structure in which two variable pixels, in which color display of a superposition type variable pixel can be performed, are superimposed, corresponding to the embodiment of FIG.

As shown in FIG. 6, when R, G, and B color elements are arranged by dividing one pixel area into three, each of R, G, and B is occupied by one third of the entire spectral band The brightness of the primary color is limited to 1/9 of the incident white and 1/3 of the brightness of the white. This brightness is actually smaller because it is a result of assuming that each of red (R), green (G), and blue (B) occupies 1/3 of the entire spectral band.

As shown in Fig. 7, when the area division is reduced to two, assuming that the spectral bandwidth for representing the same primary color is the same, the brightness of the primary color is 1/3 of the incident white and 1/3 of the brightness of white. Therefore, the brightness of the primary color is three times higher than that of the existing three primary color filters, so that a very shiny and brilliant color can be expressed. The brightness of white is basically unchanged because it depends on the spectrum width when the area is divided, but the brightness of white can also be improved by adjusting the spectral width of the color display device variably.

8, when the color filters of the color variable pixels are used in a superposed manner, the color variable range of the color filter becomes the entire range from the blue color to the red color in both of the upper and lower filters, The brightness of the composite color and the brightness of the white color can be doubled as compared with the area division. That is, the brightness of the primary color is 1/3 of the incident white and the brightness of the white is 2/3.

FIG. 9 is a graph schematically illustrating the brightness characteristics of the color display according to the color display systems of FIGS. 6 to 8. FIG.

As can be seen from FIG. 9, when the color filter is configured to be color-tunable as compared with the conventional three-color separation, the brightness of the primary color can be improved at least twice and the brightness of the composite color can be greatly improved Able to know. It can also be seen that the brightness of the white color can be greatly increased by using color filters that are capable of color change.

1,1 '... reflective color filters 10,10a, 10b ... photonic crystal panels
11, 13 ... first and second photonic crystal regions 20 ... absorption plate
30, 30a, 30b ... Shutters 31, 33 ... First and second shutter areas
50 ... control unit

Claims (8)

And a variable photonic crystal which reflects light of a selected wavelength band from external light and whose optical band gap corresponding to a frequency bandwidth that reflects light by a stimulus is controlled so that the first and second photonic crystal regions, And the second photonic crystal region to adjust the photonic bandgap of the variable photonic crystal of the first and second photonic crystal regions, respectively, by a combination of the selective wavelength bands reflected in the first and second photonic crystal regions, A reflection type color filter having a two-dimensional array of regions including the first and second photonic crystal regions corresponding to one pixel;
And a shutter for variably changing the transmittance of light and variably controlling the amount of light incident on the first and second photonic crystal regions,
Wherein the variable photonic crystal includes a photonic crystal in which nanoparticles of a high refractive index dielectric are distributed in a crystal form in a surrounding environment where a volume is changed by a stimulus given by the controller,
Wherein the shutter is provided for each pixel to adjust the amount of light incident on each of the first and second photonic crystal regions located in each pixel so as to display an image of a desired color with desired brightness. 2. The method according to claim 1, wherein the first and second photonic crystal regions are arranged in a horizontal direction and the first and second photonic crystal regions are formed for each region corresponding to one pixel, Dimensional array of the reflection type color display device. The liquid crystal display device according to claim 1, further comprising a first photonic crystal panel having the first photonic crystal region and a second photonic crystal panel having the second photonic crystal region for each pixel corresponding to one pixel, The second photonic crystal panel has an overlapping structure,
And a second shutter positioned between the first and second photonic crystal panels, wherein the shutter includes a first shutter positioned on the side where external light is incident, and a second shutter positioned between the first and second photonic crystal panels, Reflection type color display device. The reflection type color display device according to any one of claims 1 to 3, wherein the reflection type color filter further comprises an absorption plate below the first and second photonic crystal regions. The optical semiconductor device according to any one of claims 1 to 3, wherein each of the first and second photonic crystal regions has a shape in which at least one of shape, volume, and effective refractive index is changed by electrical or mechanical conversion, And a variable-type photonic crystal. In order to display a color image using the reflection type color display device of any one of claims 1 to 3,
Adjusting a photonic bandgap of the variable photonic crystal of the first and second photonic crystal regions independently of the first and second photonic crystal regions of the reflective color filter;
And driving the shutter to variably adjust the amount of light incident on the first and second photonic crystal regions to display an image of a desired color with desired brightness. The optical semiconductor device according to claim 6, wherein each of the first and second photonic crystal regions includes a variable photonic crystal in which at least one of shape, volume, and effective refractive index is changed by electrical or mechanical conversion, / RTI > 7. The color filter according to claim 6, wherein the reflection type color filter further comprises an absorbing plate disposed under the first and second photonic crystal regions, for absorbing light transmitted through the first or second photonic crystal region, Way.

Images