KR100670819B1 - Planar display device for colorful text - Google Patents

Abstract

The present invention provides a flat panel display device that can express a variety of colors and is excellent in economy. The display device applies an optical waveguide lattice coupler for vertically color spectroscopy of white light traveling in a horizontal direction along a planar optical waveguide, and transmits or receives vertically dispersed light into a pixelated liquid crystal having a size of several microns or several millimeters. Provides the concept of a flat panel display for multi-color display that can be adjusted to display a single character composed of colorful colors.

Flat Panel Display, Multi-Color, Lattice Combiner, Vertical, Color Spectroscopy

Description

Flat display device for colorful text display

1 is a perspective view showing a flat panel display for multi-color display according to an embodiment of the present invention.

2 is a view for explaining the principle of light coupling by a grating coupler applied to a back light, which is a light source of a display according to the present invention.

3A is a cross-sectional view illustrating the formation of vertical light by the lattice coupler of the present invention, and FIG. 3B is an enlarged cross-sectional view of part A of FIG. 3A. FIG. 3c is a diagram illustrating the optical coupling principle of the grating group of the grating coupler of FIG. 3a, and FIG. 3d is a photograph showing the final distribution of light according to FIG. 3c.

4A and 4B are cross-sectional views illustrating the operating principle of a flat panel display for multi-color display.

5A is a perspective view illustrating an operating state of the display according to the present invention when no power is supplied, and FIG. 5B is a photograph showing a screen in a state of FIG. 5A. 5C is a perspective view illustrating an operating state of the display according to the present invention in a state where power is supplied, and FIGS. 5D and 5E are photographs showing a screen in a state of FIG. 5C.

6 is a cross-sectional view showing another method of irradiating white light to the display of the present invention.

<Description of the symbols for the main parts of the drawings>

102; Light emitting element 104; white light

106; Optical waveguide 108; Lattice Coupler

110; Vertical light 112; LCD

114; Upper electrode array 116; Bottom electrode array

118; Power supply 122; Electric field

124; Pixel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display, and more particularly, to a display for multi-color display that can express information such as characters using multiple colors.

In general, a liquid crystal display device is composed of a glass substrate, a polarizer, a transparent electrode, and a liquid crystal, and is a display device that displays characters by inducing light blocking depending on whether or not voltage is applied to electrodes disposed above and below the liquid crystal. However, the liquid crystal display device is configured such that the color of the so-called back light used for indirect light emission uses only a single color. Therefore, there is a limit in expressing information such as a multi-colored character or logo composed of various colors. To display information such as colored single characters, it can be replaced by TFT-LCD or OLED, but the pixel size of the unit liquid crystal is very small in microns. Accordingly, as the size of information such as a character to be displayed increases, a liquid crystal display having a large number of pixels is required.

On the other hand, in order to adjust the image information of the unit liquid crystals, a TFT electrode array which is very complicated is required, and accordingly, power consumption for driving the circuit is large. In addition, the narrow field angle of the screen (performance) is the biggest disadvantage, and the weakness in external pressure (pressing). In particular, there is a problem of high production equipment and manufacturing costs.

Therefore, the technical problem to be achieved by the present invention is to provide a flat panel display that can express a variety of colors, and excellent economic efficiency.

The display device according to the present invention for achieving the above technical problem is to apply an optical waveguide grating coupler for color spectroscopy of the white light traveling in the horizontal direction along the planar optical waveguide in the vertical direction, and the presence or absence of transmission of vertically dispersed light several microns Alternatively, the present invention provides a concept of a multi-color flat panel display capable of displaying a single character composed of various colors by adjusting the pixelated liquid crystal of several millimeters in size. It also provides a low-cost mass production method for flat panel displays for multi-color character display.

According to an aspect of the present invention, there is provided a light emitting device for generating light having various wavelengths, an optical waveguide coupled to one side of the light emitting device, and configured to advance the light in a horizontal direction. It is disposed vertically spaced apart from each other on the upper surface, and includes a lattice combiner consisting of a plurality of gratings to combine the horizontal light traveling in the horizontal direction in the vertical direction to emit vertical light having various wavelengths.

The vertical light of various wavelengths emitted by the lattice combiner is used as a backlight. The grating may be a grating capable of color separation and color dispersion.

The grid coupler may be composed of a plurality of grids spaced apart at regular intervals. The lattice combiner may be divided into a plurality of grid groups including a plurality of grids, and the grid groups may be spaced apart from each other at different intervals. The grating combiner may control the wavelength of the vertical light by adjusting the distance between the grating groups.

The grids of each of the plurality of grid groups may be arranged to be spaced at regular intervals. The spacing between the plurality of grid groups may be arranged in increasing or decreasing form.

The optical waveguide and the lattice combiner may be manufactured by an ultraviolet embossing process or a hot embossing process. The optical waveguide may be configured of a plurality of optical waveguides or an optical waveguide divider. The optical waveguide may have a planar structure to minimize the loss of light traveling from the light source to the grating coupler. The optical waveguide may be a multimode optical waveguide in which various optical waveguides are formed in the optical waveguide to minimize the optical coupling loss between the light source and the optical waveguide and to increase the optical coupling efficiency coupled in the vertical direction in the lattice combiner. have.

The lower portion of the grating coupler may further include a reflecting plate inclined to supply the white light of the same intensity to the grating coupler.

The backlight may be positioned below the grid coupler to supply white light directly to the grid combiner. The optical waveguide or the lattice coupler may be made of a polymer material having excellent light transmittance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention illustrated in the following may be modified in many different forms, and the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. In the drawings, the size or thickness of films or regions may be exaggerated or morphologically shown for clarity. Also, like reference numerals denote like elements throughout the specification.

1 is a perspective view showing a flat panel display for multi-color display according to an embodiment of the present invention.

Referring to FIG. 1, a flat panel display includes a light emitting element 102 emitting white light 104, an optical waveguide 106 for driving white light 104 in a horizontal direction, and a traveling light in a horizontal direction in a vertical direction. The optical waveguide grating combiner 108 which changes the direction and induces color spectroscopy, the liquid crystal 112 which controls the transmission of the vertically-spectralized vertical light 110, and the upper part which controls the operation of the liquid crystal 112. An electrode array 114 and a lower electrode array 116 are included. At this time, the white light 104 is composed of horizontal light of various wavelengths. The optical waveguide 106 is disposed on the transparent substrate 100.

The grating combiner 108 is vertically spaced apart from each other on an upper surface of the optical waveguide 106, and combines the white light 104 traveling in the horizontal direction in a vertical direction to emit a vertical light 110 having various wavelengths. Consists of two grids. In this case, the plurality of gratings are preferably capable of color separation and color dispersion.

Here, the upper electrode arrays 114, which are rectangular in the shape of several microns to several millimeters, may operate independently of each other. That is, each upper electrode array 114 may be independently controlled by a power array 118 that supplies electricity from the outside. In addition, each upper electrode array 114 corresponds to an individual pixel. Each pixel controls the presence or absence of the vertical light 110 by the power source array 118 to form a colorful image by combining a plurality of pixels. For example, according to the display of the present invention, it is possible to display a keypad composed of multi-colored characters and a logo such as a trade name / brand name.

2 is a view for explaining the principle of light coupling by a grating coupler applied to a back light, which is a light source of a display according to the present invention.

Referring to FIG. 2, the white light 104 traveling in the horizontal direction is changed into a vertical light 110 by changing the traveling direction of the light in the vertical direction by the lattice coupler 108 which is a lattice-shaped structure. That is, according to the period, shape and height of the grating, light of a particular wavelength is selectively spectroscopically combined in the vertical direction. This is called optical coupling. The principle of optical coupling can be explained by Equation 1 below.

Δ = λ / (2 n cosα)

Λ is the wavelength of light coupled to the grating coupler 108, n is the refractive index of the grating, Δ is the spacing of the gratings, and α is 1/2 of the slope of the vertical light 110 coupled to the grating coupler 108. For example, the lattice combiner 108 having a refractive index n of 1.5 and an interval Δ of a lattice of 306.4 nm spectroscopically combines red light of about 650 nm in the vertical direction by Equation (1).

3A is a cross-sectional view illustrating the formation of vertical light by the lattice coupler of the present invention, and FIG. 3B is an enlarged cross-sectional view of part A of FIG. 3A. FIG. 3c is a diagram illustrating the optical coupling principle of the grating group of the grating coupler of FIG. 3a, and FIG. 3d is a photograph showing the final distribution of light according to FIG. 3c.

3A and 3B, white light 104 of various wavelengths emitted from the light emitting device 102 travels along the optical waveguide 106 in the horizontal direction. The optical waveguide 106 may be arranged with a plurality of optical waveguides 106 or may be configured as an optical waveguide 106 distributor. In this case, the optical waveguide 106 preferably has a planar structure so that most of the light emitted from the light emitting device 102 is transmitted to the lattice combiner 108. Application of the planar optical waveguide 106 can minimize light loss.

In addition, by designing a single-mode optical waveguide 106 in which a single optical waveguide path is formed in the optical waveguide 106 to a multi-mode optical waveguide 106 in which various optical waveguide paths are formed. In addition, the optical coupling loss between the light emitting device 102 and the optical waveguide 106 is minimized, and the optical coupling efficiency coupled to the vertical direction in the grating coupler 108 is maximized.

Subsequently, the white light 104 which is the horizontal light traveling in the horizontal direction reaches the grating combiner 108 including the grating arranged in the vertical direction. At this time, the white light 104 having a specific wavelength having a specific color is converted into vertical light 110 in the vertical direction by the light coupling principle of the diffraction grating according to Equation 1 in the lattice combiner 108.

The selectivity of the color (ie, wavelength) of the grating coupler 108 depends on the refraction index of the grating as well as the optical waveguide 106 constituting the grating coupler 108. The period of the grating may be determined by dividing gratings (lattice groups) having the same spacing, for example, as shown by reference numerals 108a and 108b 108c of FIG. 3B. Therefore, by periodically changing the period of the grating constituting the grating combiner 108 as shown in Figure 2b, it is possible to configure a variety of colors (ie, wavelength) of the vertical light 110 is vertically coupled. The optical waveguide 106 and the lattice combiner 108 may be manufactured by an ultraviolet embossing process or a hot embossing process. The optical waveguide 106 or the lattice combiner 108 may be made of a polymer material having excellent light transmittance.

As shown in FIG. 3C, the white light 104 traveling in the horizontal direction is converted into vertical light having different wavelengths according to the period of the grating constituting the optical waveguide grating combiner 108. That is, the first grating group 108a of FIG. 3B is vertical light 110a of one wavelength, the second grating group 108b is vertical light 110b of two wavelengths, and the third grating group 108c is vertical light of three wavelengths ( 110c) at the same time. For example, the optical waveguide grating coupler 108 composed of the refractive index n of the diffraction grating is 1.5 and the grating spacing is 306.4 nm, 301.7 nm, and 297.0 nm, respectively, is represented by 650 nm, 640 nm, and 630 nm, respectively. The three colors of red, orange and yellow are simultaneously optically combined. On the other hand, the spacing of the plurality of grid groups may be arranged in an increasing or decreasing form.

As shown in FIG. 3D, the horizontal light propagating into the white light 104 is very dense and due to the arrangement of periodic and repetitive gratings within the grating combiner 108, wavelengths with adjacent vertical light, eg 110a, 110b 110c. The difference in is not large, and as a result is spectroscopically perpendicular to iridescent light, on a principle similar to the color spectroscopy by the prism. Vertical light 110 vertically spectroscopic in iridescent light is used as the back light of a flat panel display for active multi-color display.

4A and 4B are cross-sectional views illustrating the operating principle of a flat panel display for multi-color display.

Referring to FIG. 4A, white light 104 composed of various wavelengths emitted from the light emitting device 102, for example, λ 1, λ 2, λ 3, λ 4, λ 5, and λ 6, runs along the optical waveguide 106 in the horizontal direction. . The white light 104 reaches the grating of the optical waveguide grating coupler 108, and the vertical light 110 is vertically coupled at the same time as the traveling direction is changed in the vertical direction according to the principle of the optical waveguide grating coupler 108 according to Equation (1). Spectroscopy). In this case, the color (wavelength) of the spectroscopic vertical light 110 varies depending on the spacing and position of the lattice combiner 108. That is, a lattice group is vertical light of λ1, b lattice group is vertical light of λ2, c lattice group is vertical light of λ3, d lattice group is vertical light of λ4, e lattice group is vertical light of λ5 and f lattice group Is converted into vertical light of? 6. Since the vertical light having various wavelengths, that is, spectroscopically colored in various colors, is not supplied with power, it is not transmitted in the vertical direction by the opaque liquid crystal 112.

As shown in FIG. 4B, when electricity is supplied to the upper electrode array 114 and the lower electrode 116 by the power source 118, the electric field 122 is formed between the liquid crystals 112. The state of the transparent liquid crystal 112 is changed. The vertical light 110 passes through the transparent liquid crystal 112 (vertical light of λ2, vertical light of λ4 and vertical light of λ6 in FIG. 4B).

Specifically, the size of the upper electrode array 114 is divided into rectangles of several microns (μm) to several millimeters (mm) and divided into independent electrode arrays, and electricity is supplied to each electrode array independently. The vertical light 110 may be partially transmitted by an independent electric supply, and each independent electrode array corresponds to a unit pixel. By adjusting the independent light transmission of the unit pixel, it is possible to represent a character or an image composed of several pixels. Since the colors (wavelengths) of the vertical light 110 transmitted through the unit pixels may be expressed differently, single letters or words and logos composed of various colors may be represented through respective pixel arrays composed of various colors.

5A is a perspective view illustrating an operating state of the display according to the present invention when no power is supplied, and FIG. 5B is a photograph showing a screen in a state of FIG. 5A. 5C is a perspective view illustrating an operating state of the display according to the present invention in a state where power is supplied, and FIGS. 5D and 5E are photographs showing a screen in a state of FIG. 5C.

5A and 5B, the upper electrode array 114 is subdivided into rectangles having a size of several microns (μm) or several millimeters (mm) to fabricate an independent electrode array. Independent electrode arrays 114 correspond to independent pixels 124. When no electricity is supplied to the electrode array 114, the electric field is not formed in each electrode array 114, so that the liquid crystal 112 is maintained in an opaque state. Accordingly, the vertical light 110 composed of various colors does not transmit in the vertical direction. Accordingly, as illustrated in FIG. 5B, each pixel 124 is represented by a dark portion.

Referring to FIGS. 5C through 5E, the electrode array 114 supplied with electricity by the power source 118 transmits the vertical light 110 of a specific color (wavelength) to light the bright portion 124b of the pixel 124. Form. The electrode array 114 that is not supplied with electricity blocks the vertical light 110 to form a dark portion 124a of the pixel 124. That is, each electrode array 114 corresponds to the bright portion 124b and the dark portion 124a of the pixel 124. By controlling the supply of electricity to each pixel 124 to control the dark and clear, it is possible to express the information by the desired character or image.

Since the color (wavelength) of the vertical light 110 transmitted from each pixel 124 is transmitted by the light spectroscopy by the optical waveguide grating combiner 108, each pixel 124 has a different color according to its position. It emits light. That is, as shown in Figs. 4D and 4E, it is possible to obtain information such as character arrangements composed of various colors. Here, the upper electrode array 114 uses a conductive thin film such as indium tin oxide (ITO) having excellent light transmittance.

6 is a cross-sectional view showing another method of irradiating white light to the display of the present invention.

Referring to FIG. 6, the white light 104 emitted from the light emitting device 102 may proceed vertically without passing through the optical spectroscopy coupling principle of the planar optical waveguide grating coupler 108 through the inclined reflector 130. The vertically reflected vertical light 110 passes through a grating and is spectrated as light of various colors (wavelengths) and is supplied to the liquid crystal 112. Hereinafter, information display such as letters composed of various colors may be performed by controlling the transmittance of the liquid crystal 112 in the same principle as described with reference to FIGS. 4A to 5E.

The flat panel display for multi-color display according to the present invention can implement information such as keypad characters, trade names, or logos of electronic devices, which have been previously displayed only in a single color, with information composed of various colors. Accordingly, it is possible to colorize information such as a keypad of a portable terminal or a display of a manufacturer's name and trademark. In addition, it is possible to provide core component technology that can improve the added value of related devices by dramatically improving the external design of the mobile display device in the future. Furthermore, the display of the present invention is simple in structure and manufacturing method, and the power consumption is also significantly lower than that of a conventional flat panel display, thereby enabling low-cost mass production. Accordingly, in the future, it can be variously used for next-generation mobile electronic devices of low price and low power consumption.

According to the flat panel display for multi-color display according to the present invention described above, it is possible to provide a variety of colors having a variety of wavelengths by vertically spectroscopically grating a white horizontal light having a variety of wavelengths by a grating combiner.

In addition, by adjusting the transmittance of the vertical light spectroscopically using the liquid crystal, information such as desired characters can be expressed using various colors.

Claims (15)

Light emitting device for generating light having various wavelengths; An optical waveguide coupled to one side of the light emitting device and configured to advance the light in a horizontal direction; And A plurality of lattice couplers comprising a plurality of gratings attached to an upper surface of the optical waveguide and spaced apart from each other to be vertically disposed so as to emit vertical light having various wavelengths by combining horizontal light traveling in the horizontal direction in a vertical direction Flat panel display element for color display.  The flat panel display device of claim 1, wherein the vertical light of various wavelengths emitted by the lattice combiner is used as a backlight. The flat panel display device of claim 1, wherein the grating is a grating capable of color separation and color dispersion. The flat panel display device of claim 1, wherein the lattice combiner comprises a plurality of lattices spaced at regular intervals. The flat panel display of claim 1, wherein the grid combiner is divided into a plurality of grid groups including a plurality of grids, and the grid groups are spaced apart from each other at different intervals. The flat panel display device of claim 5, wherein the lattice combiner controls the wavelength of the vertical light by adjusting the distance between the lattice groups. The flat panel display of claim 5, wherein the grids of each of the plurality of grid groups are arranged to be spaced at regular intervals. The flat panel display device of claim 5, wherein the spacing between the plurality of grid groups is arranged in an increasing or decreasing manner. The flat panel display device of claim 1, wherein the optical waveguide and the lattice coupler are manufactured by an ultraviolet embossing process or a hot embossing process. The flat panel display device of claim 1, wherein the optical waveguide comprises a plurality of optical waveguides or an optical waveguide divider. The flat panel display device of claim 1, wherein the optical waveguide has a flat structure to minimize the loss of light from the light source to the lattice coupler. The optical waveguide of claim 1, wherein the optical waveguide has various optical waveguides formed in the optical waveguide for minimizing optical coupling loss between the light source and the optical waveguide and increasing optical coupling efficiency coupled vertically in the lattice combiner. A flat panel display device for multi-color display, characterized in that the multi-mode optical waveguide. The flat panel display of claim 1, further comprising an inclined reflector under the grid combiner to supply white light having the same intensity to the grid combiner. The flat panel display of claim 2, wherein the backlight is positioned under the grid combiner to directly supply white light to the grid combiner. The flat panel display device of claim 1, wherein the optical waveguide or the lattice coupler is made of a polymer material having excellent light transmittance.

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