Patent Publication Number: US-2011069369-A1

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2009-0089969 filed on Sep. 23, 2009, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Exemplary embodiments of the present invention relates to a display device, more particularly, the present invention relate to a display device capable of realizing images by using micro-electro-mechanical systems (MEMS). 
     2. Description of the Background 
     Various types of flat panel displays have been adopted as a next generation display device. For example, a flat panel display can provide user with a thin but fine quality image by using micro-electro-mechanical system (MEMS). The MEMS is a micro-minute processing technique that offers to process an electronic device having a size ranging from several nanometers to several millimeters. The using of the MEMS has resulted in high photo-efficiency that has found significant success in manufacturing the liquid crystal display. 
     However, the display device using a traditional MEMS has only an on-off characteristic such as for reflecting or not, or closing or opening a shutter. Accordingly, the MEMS element must be driven several times during a short time for representing grays and colors. A conventional display device includes light sources emitting at least three colors such that the light sources are required to sequentially driven by the time division scheme, and simultaneously, the MEMS of each subpixels need to be driven together to represent the desired color—consequently rendering a process difficult to obtain a high speed driving margin when it is applied to a large area display device. As a result, the driving margin is narrow. 
     Therefore, there is a need of a display device providing a simple process yet a high speed driving margin. 
     SUMMARY OF THE INVENTION 
     These and other needs are addressed by the present invention, in which exemplary embodiments provide a display device capable of easily realizing colors compared with a conventional display device. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     Still other aspects, features, and advantages of the present invention are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive. 
     Exemplary embodiments of the present invention disclose a display device. The device includes a first substrate and a second substrate facing the first substrate. The device also includes a micro-electro-mechanical system (MEMS) element disposed between the first substrate and the second substrate. The device includes a color conversion member disposed between one of the first substrate, the second substrate, and the MEMS element. The device further includes a light source to emit light toward the first substrate. The color conversion member is configured to absorb the emitted light and to represent at least one color that is different wavelength of the emitted light by absorbing the emitted light. 
     Exemplary embodiments of the present invention disclose a method for manufacturing a liquid crystal display. The method includes disposing one substrate facing another substrate to form a micro-electro-mechanical system (MEMS) element between the substrates. The method also includes forming a color conversion member between one of the respective substrate and the MEMS element. The method also includes providing a light source to emit light, wherein the color conversion member is provided to selectively absorb one or more wavelengths of the emitted light that is not represent for display. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a cross-sectional view of a display device, according to exemplary embodiments of the present invention. 
         FIG. 2  is a top plan view of an exemplary arrangement of a pixel of the display device of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of a display device, according to exemplary embodiments of the present invention. 
         FIG. 4  is a cross-sectional view of a display device, according to exemplary embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     An apparatus and method of manufacturing display device is disclosed. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It is apparent, however, to one skilled in the art that the present invention may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the present invention. 
     It is understood that when an element such as a layer, a film, a region, or a substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
     Now, a display device according to exemplary embodiments of the present invention is described with reference to  FIG. 1  and  FIG. 2 . 
       FIG. 1  is a cross-sectional view of a display device, according to exemplary embodiments of the present invention, and  FIG. 2  is a top plan view of an exemplary arrangement of a pixel of the display device of  FIG. 1 . 
     Referring to  FIG. 1  and  FIG. 2 , a display device may include a display panel  100  including a lower substrate  110  and an upper substrate  210  facing each other, and a backlight unit  300  is configured to provide light to the display panel  100 . 
     The lower substrate  110  and the upper substrate  210  may be made of a transparent insulating material such as transparent glass or plastic. 
     An aperture plate  120  having a plurality of lower openings  91   a ,  91   b ,  91   c , and  91   d  may be formed on the lower substrate  110 . The aperture plate  120  can be made of a material that blocks the light from reaching the lower substrate  110 , and may allow to pass the light through the plurality of openings  91   a ,  91   b ,  91   c , and  91   d.    
     A shutter  230  having a plurality of upper openings  231   a ,  231   b ,  231   c , and  231   d  and a shutter driving member  220  can be formed on the upper substrate  210 . 
     The upper openings  231   a ,  231   b ,  231   c , and  231   d  of the shutter  230  may have the same plane shape as that of the lower openings  91   a ,  91   b ,  91   c , and  91   d  of the aperture plate  120 . The shutter  230  may be moved in the direction parallel to the substrates  110  and  210 , along with a horizontal direction based on the substrate, and when the shutter  230  is positioned at a reference position, the shutter  230  may cover the lower openings  91   a ,  91   b ,  91   c , and  91   d  of the corresponding aperture plate  120 . However, it is noted that the shape of the upper openings  231   a ,  231   b ,  231   c , and  231   d  may be different from the shape of the lower openings  91   a ,  91   b ,  91   c , and  91   d . By moving the shutter  230 , the lower openings  91   a ,  91   b ,  91   c , and  91   d  and the upper openings  231   a ,  231   b ,  231   c , and  231   d  can be aligned to corresponding to one another. In some examples, the lower openings  91   a ,  91   b ,  91   c , and  91   d  may be covered by an opaque portion of the shutter  230 , and the shape of the upper openings  231   a ,  231   b ,  231   c , and  231   d  and the lower openings  91   a ,  91   b ,  91   c , and  91   d  may variously be changed. 
     The shutter  230  can be connected to the shutter driving member  220  supporting the shutter  230  to be floated on the upper substrate  210  and that is capable of moving the shutter  230  at the reference position in the horizontal direction. The shutter driving member  220  may control the shutter  230  to move in the right and left directions, and may have an elastic force to return the shutter  230  to the reference position after the shutter  230  is moved in the right and left directions. 
     Each shutter  230  may be separated, and two or more shutters  230  are connected to each other by way of configuration of manufacturing process. 
     The display panel  100  may further include a color conversion member  400  disposed between the lower substrate  110  and the upper substrate  210 . The color conversion member  400  may include a first color conversion member  401   a , a second color conversion member  401   b , a third color conversion member  401   c , and a fourth color conversion member  401   d.    
     Each pixel P of the display panel  100  may include a first subpixel P 1 , a second subpixel P 2 , a third subpixel P 3 , and a fourth subpixel P 4 . 
     The lower openings  91   a ,  91   b ,  91   c , and  91   d  of the lower substrate  110 , may include one shutter  230  corresponding thereto, and the shutter driving member  220  may form one MEMS element. 
     Next, an operation of the MEMS element will be described. 
     When the shutter  230  is positioned at the reference position by the shutter driving member  220 , the shutter  230  may cover the lower openings  91   a ,  91   b ,  91   c , and  91   d  to block the light from passing through the lower openings  91   a ,  91   b ,  91   c , and  91   d  thereby forming a black color because the light cannot be reached. In some examples, when the shutter  230  is horizontally moved by the shutter driving member  220 , the upper openings  231   a ,  231   b ,  231   c , and  231   d , and the lower openings  91   a ,  91   b ,  91   c , and  91   d  can be aligned such that the light passing through the lower openings  91   a ,  91   b ,  91   c , and  91   d  can be reached to the respective upper openings  231   a ,  231   b ,  231   c , and  231   d . As a consequence, the light may be emitted to an external region of the upper openings  231   a ,  231   b ,  231   c , and  231   d  that can be recognized. In some examples, the corresponding alignment degree of the upper openings  231   a ,  231   b ,  231   c , and  231   d  and the lower openings  91   a ,  91   b ,  91   c , and  91   d  may be adjusted to display colors, for example, a gray. The adjustment can be controlled by adjusting the distance of the horizontal movement of the shutter  230 . 
     For example, the shutters  230  disposed in respective of the first subpixel P 1 , the second subpixel P 2 , the third subpixel P 3 , and the fourth subpixel P 4  may be driven separately such that the subpixels may display different tone of gray. 
     The backlight unit  300  may include a light source (not shown) and a supporting unit (not shown) to provide the light source. The display device according to exemplary embodiments of the present invention may include a blue light source or a white light source. For example, a blue light emitting diode (LED) or an ultra violet (UV) diode may be included. As the light source, by way of configuration, a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL), or a discharge lamp (DL) instead of the light emitting diode (LED), may be used as an example. The supporting unit may include a reflection member (not shown) to guide the light emitted from the light source toward the lower substrate  110 . 
       FIG. 2  is a top plan view of an exemplary arrangement of a pixel of the display device of  FIG. 1 . Referring to  FIG. 2 , a first subpixel P 1  is provided to display a first color, a second subpixel P 2  is provided to display a second color, a third subpixel P 3  is provided to display a third color, and a fourth subpixel P 4  is provided to display a fourth color, and these subpixels may alternately be provided. 
     In some examples, the first subpixel P 1 , the second subpixel P 2 , and the third subpixel P 3  as a unit pixel to realize full-color display as one of primary colors such as a red, a green, and a blue, or a magenta, a yellow and a cyan. For example, the fourth subpixel P 4  may display a white. By adding the pixel with the white color, the luminance may be increased. By way of configuration of manufacturing process, the fourth subpixel P 4  may be omitted. 
     The subpixels including the first subpixel P 1 , the second subpixel P 2 , the third subpixel P 3 , and the fourth subpixel P 4  may be formed one group form one pixel, and may repeatedly be arranged according to rows and/or columns. However, the arrangement and the shape of the pixels may variously be changed by way of configurations. 
     For example, the lower opening  91   a , the upper opening  231   a , and the first color conversion member  401   a  may be disposed on the region of the first subpixel P 1 , the lower opening  91   b , the upper opening  231   b , and the second color conversion member  401   b  may be disposed on the region of the second subpixel P 2 , the lower opening  91   c , the upper opening  231   c , and the third color conversion member  401   c  may be disposed on the region of the third subpixel P 3 , and the lower opening  91   d , the upper opening  231   d , and the fourth color conversion member  401   d  may be disposed on the region of the fourth subpixel P 4 . 
     The color conversion member  400  may be disposed at the position corresponding to the respective of the lower openings  91   a ,  91   b ,  91   c , and  91   d  of the aperture plate  120 . 
     The color conversion member  400  may be made of one material selected from the group consisting of polydiacetylene, transacetylene, phosphor, nanocrystal, and quantum dots (CdSe/ZnS, CdS/ZnS, InGaP/ZnS). 
     For example, among the first color conversion member  401   a , the second color conversion member  401   b , and the third color conversion member  401   c , the red conversion member may include one material selected from the group consisting of CaAlSiN3:Eu, (Sr,Ca)AlSiN3:Eu, Y(V,P)O4:Eu, (Y,Gd)BO3:Eu, and combinations of the group, and the green conversion member may include one material selected from the group consisting of (Ba,Sr)2SiO4:Eu, Ca3(Sc,Mg)2Si3O12:Ce, CaSc2O4:Ce, Zn2SiO4:Mn, (Zn,A)2SiO4:Mn, and combinations of the group. 
     In some examples, the composition for the formation of the color converting members  400  can be manufactured by dispersing a material with a controlled stoichiometric ratio in a vehicle in which a binder resin can be dissolved with a solvent. Examples of the binder resin may include a cellulose resin such as ethyl cellulose or an acryl resin, but they are not limited thereto. The solvent may be an organic solvent such as hexanetriol, polypropylene glycol, butyl carbitol acetate, and terpineol, but is not limited thereto. Also, since the manufacture of the composition for the formation of the color converting member  400  may be an example, therefore, the manufacturing method of the composition is not limited thereto. 
     The color converting member  400  may be formed by manufacturing the composition with a desired shape through various methods such as a photolithography, a screen printing, an inkjet printing, and a laser printing. 
     The first color conversion member  401   a  can absorb the light L incident from the light source to obtain the energy thereby emitting the first color L 1  such that the first subpixel P 1  can display the first color L 1 . The second color conversion member  401   b  can absorb the light L incident from the light source to obtain the energy thereby emitting the second color L 2  such that the second subpixel P 2  can display the second color L 2 . The third color conversion member  401   c  can absorb the light L incident from the light source to obtain the energy thereby emitting the third color L 3  such that the third subpixel P 3  can display the third color L 3 . And the fourth color conversion member  401   d  can absorb the light L incident from the light source to obtain the energy thereby emitting the fourth color L 4  such that the fourth subpixel P 4  displays the fourth color L 4 . A combination of the first color L 1 , the second color L 2 , the third color L 3 , and the fourth color L 4  can display the desired various types of images. 
     For the purpose of illustration of embodiments, when the backlight unit  300  only includes a blue light source, and the first subpixel P 1 , the second subpixel P 2 , and the third subpixel P 3  can be the pixels respectively displaying a red, a green, and a blue. In this example, the third color conversion member  401   c  of the third subpixel P 3  may be omitted. That is, the color conversion member can display the blue among the first color conversion member  401   a , the second color conversion member  401   b . In this example, the third color conversion member  401   c  of the color conversion member  400  may be omitted. 
     For the purpose of illustration of embodiments, when the backlight unit  300  only includes the white color light source, the fourth color conversion member  401   d  of the fourth subpixel P 4  may be omitted. That is, the color conversion member can display the white color among the color conversion members  400  that may be omitted. 
     It is contemplated that one color conversion member may be omitted according to the color of the light source such that the structure of the display device and the manufacturing process may be simplified, and the manufacturing cost of the display device may be reduced. 
     In some examples, the shutter  230  may be positioned in each of the subpixel P 1 , subpixel P 2 , subpixel P 3 , and subpixel P 4  that can be disposed on the respective reference position. The shutter  230  can be moved in a horizontal direction by the shutter driving member  220  disposed in the subpixel P 1 , subpixel P 2 , subpixel P 3 , and subpixel P 4  of the pixel P such that the light emitted from the backlight unit  300  can pass through the lower openings  91   a ,  91   b ,  91   c , and  91   d , the color conversion members  401   a ,  401   b ,  401   c , and  401   d , and through the upper openings  231   a ,  231   b ,  231   c , and  231   d  of the desired region of the subpixels P 1 , P 2 , P 3 , and P 4  thereby being displayed. Accordingly, one pixel P can display the desired color using by the combination of the colors represented by the subpixel P 1 , subpixel P 2 , subpixel P 3 , and subpixel P 4 . 
     According to the exemplary embodiments of the present invention, a display device may include one light source configured to emit one color, for example, a blue or a white, and also may include the color conversion member  400  to convert the blue light or the white color light into a desired colors such that the light source may not sequentially be driven by a time division scheme, and the light source can only be driven by on/off. According to exemplary embodiments of the present invention, it is contemplated that without the time division scheme associated with driving the light source, the desired color may be represented by the on/off of the MEMS of each subpixel such that the driving method can be simplified. As a consequence of the simplification of the process, it is applicable to the large area of the display device. 
     Next, a display device according to exemplary embodiments of the present invention will be described with reference to  FIG. 3 .  FIG. 3  is a cross-sectional view of a display device according to exemplary embodiments of the present invention. 
     Referring to  FIG. 3 , a display device may include a display panel  100  including a lower substrate  110  and an upper substrate  210  facing each other, and a backlight unit  300  is configured to provide light to the display panel  100 . 
     In some examples, an aperture plate  120  having a plurality of lower openings  91   a ,  91   b ,  91   c , and  91   d  can be formed on the lower substrate  110 . A color conversion member  400  including a first color conversion member  401   a , a second color conversion member  401   b , a third color conversion member  401   c , and a fourth color conversion member  401   d  can be formed on the upper substrate  210 , a reflection member  500  can be formed on the color conversion member  400 , and a shutter  230  having a plurality of upper openings  231   a ,  231   b ,  231   c , and  231   d  and a shutter driving member  220  can be formed. 
     However, a different aspect from the display device of  FIG. 1  may be provided, according to exemplary embodiments of the present invention in which the color conversion member  400  may be formed on the upper substrate  210 , and the reflection member  500  can be formed on the color conversion member  400 . The reflection member  500  may be provided to transmit a portion of the light and to reflect a portion of the light according to a wavelength of the light. For example, when the light source is blue light, the blue light may be transmitted and the remaining light may be reflected, and when the light source is white light, the white light may be transmitted and the remaining light may be reflected. 
     The reflection member  500  can be configured to prevent back-scattering after the color conversion member  400  absorbs the light L of the light source passing through the backlight unit  300 , the lower openings  91   a ,  91   b ,  91   c , and  91   d , and the upper openings  231   a ,  231   b ,  231   c , and  231   d . In some examples, the first color L 1 , the second color L 2 , the third color L 3 , the fourth color L 4  generated from the energy of the absorbed light can be emitted from the color conversion member  400  such that the efficiency of the light emitted from the color conversion member  400  is increased, and thereby the quality of color display may be increased. 
     Various aspects of the exemplary embodiments according to  FIG. 1  and  FIG. 2  can be applied to the present invention. 
     Next, a display device will be described with reference to  FIG. 4 .  FIG. 4  is a cross-sectional view of a display device, according to exemplary embodiments of the present invention. 
     Referring to  FIG. 4 , a display device may include a display panel  100  including a lower substrate  110  and an upper substrate  210  facing each other, and a backlight unit  300  is configured to provide light to the display panel  100 . 
     In some examples, an aperture plate  120  having a plurality of lower openings  91   a ,  91   b ,  91   c , and  91   d  can be formed on the lower substrate  110 . A plurality of blue light filters  600   a ,  600   b , and  600   d  can be formed on the upper substrate  210 . A color conversion member  400  including a first color conversion member  401   a , a second color conversion member  401   b , a third color conversion member  401   c , and a fourth color conversion member  401   d  can be formed on the blue light filters  600   a ,  600   b , and  600   d . And a shutter  230  having a plurality of upper openings  231   a ,  231   b ,  231   c , and  231   d  and a shutter driving member  220  can be formed on the color conversion member  400 . Also, a backlight unit  300  of the display device may include a light source emitting blue light. 
     However, a different aspect from the display device of  FIG. 1 , the color conversion member  400  can be formed on the upper substrate  210 , and the blue light filters  600   a ,  600   b , and  600   d  can be formed between the upper substrate  210  and the color conversion member  400 . 
     When the color conversion member  400  absorbs the blue light L passing through the lower openings  91   a ,  91   b ,  91   c , and  91   d , and the upper openings  231   a ,  231   b ,  231   c , and  231   d , and convents the blue light L into the first color L 1 , the second color L 2 , and the fourth color L 4  after the backlight unit  300  emitting light, the blue light filters  600   a ,  600   b , and  600   d  are provided to filter the blue light included in the first color L 1 , the second color L 2 , and the fourth color L 4 , and thereby the color purity of the first color L 1 , the second color L 2 , and the fourth color L 4  may be increased and a reference for determining a color displayed on the display device i.e.,—the color reproducibility of the display device may be improved. 
     Various characteristics of the exemplary embodiments according to  FIG. 1  and  FIG. 2  can be applied to the present invention. 
     A display device according to exemplary embodiments of the present invention may include a first substrate and a second substrate facing the first substrate. An MEMS element may be disposed between the first substrate and the second substrate. A color conversion member disposed between one of the first substrate and the second substrate, and the MEMS element. And a light source is provided to emit light toward the first substrate, wherein the color conversion member absorbs the light from the light source and represents at least one color by the energy of the absorbed light. 
     The color conversion member may include one material selected from the group consisting of polydiacetylene, transacetylene, phosphor, nanocrystal, and quantum dots (CdSe/ZnS, CdS/ZnS, InGaP/ZnS). 
     The MEMS element may include an aperture plate formed on the first substrate and including a plurality of first openings, a shutter formed between the first substrate and the second substrate and including a plurality of second openings, and a driving member formed on the second substrate and driving the shutter. 
     The shutter may be moved horizontally between a first position and a second position. 
     The first opening may be covered by the shutter when the shutter is disposed at the first position, and the first opening and the second opening may be disposed in one line when the shutter is disposed at the second position. 
     If the light source may emit a blue light, the color conversion member may include a red conversion member and a green conversion member. The red conversion member may absorb the blue light and emit red light, the green conversion member may absorb the blue light and emit green light, and the blue light that is not passed through the color conversion member. The red light emitted from the red conversion member, and the green light emitted from the green conversion member may be combined to display images. 
     The red conversion member may include one material selected from the group consisting of CaAlSiN3:Eu, (Sr,Ca)AlSiN3:Eu, Y(V,P)O4:Eu, (Y,Gd)BO3:Eu, and combinations thereof. 
     The green conversion member may include one material selected from the group consisting of (Ba,Sr)2SiO4:Eu, Ca3(Sc,Mg)2Si3O12:Ce, CaSc2O4:Ce, Zn2SiO4:Mn, (Zn,A)2SiO4:Mn, and combinations thereof. 
     The color conversion member may be made of one material selected from the group consisting of polydiacetylene, transacetylene, phosphor, nanocrystal, and quantum dots (CdSe/ZnS, CdS/ZnS, InGaP/ZnS). 
     The display device may further include a reflection member disposed between the first substrate and the color conversion member, and the reflection member may pass the light emitted from the light source and reflect the light of the remaining wavelengths. 
     The light source may emit blue or white light. 
     The display device may further includes a light filter disposed between the second substrate and the color conversion member, and the light filter filters light having the same wavelength range as the light emitted from the light source. 
     The light source may emit blue light. 
     The light source may be selected from the group of a light emitting diode (LED), an organic electroluminescent (EL) element, an inorganic electroluminescent (EL) element, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a discharge lamp (DL), and combinations thereof. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.