Patent Application
20080079869
The above and/or other aspects, features, and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings of which:
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.
In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or 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. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Embodiments of the present invention are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments of the present invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present invention.
The present invention is directed to enhance color reproducibility of a liquid crystal display (“LCD”) that uses a cold cathode fluorescent lamp (“CCFL”). In the present invention, a light absorption material for absorbing a particular wavelength is added to a diffusion plate to enhance color reproducibility.
First, an exemplary LCD according to one exemplary embodiment of the present invention will be described in detail with reference to
As shown in
The liquid crystal panel 137 includes a TFT array panel 132, a color filter panel 131 positioned at an upper side of the TFT array panel 132, and liquid crystal (not shown) injected between the panels 131, 132. The TFT array panel 132 includes thin film transistors (“TFTs”) (not shown) serving as switching elements formed in a matrix. Although not shown, the TFT array panel 132 also includes a gate line connected with a gate electrode of each TFT, a data line connected with a source electrode of each TFT, and a pixel electrode connected with a drain electrode of each TFT.
The data lines and gate lines are electrically connected with the data PCB 136 and the gate PCB 134 through the data TCP 135 and the gate TCP 133, respectively. Accordingly, when the data PCB 136 and the gate PCB 134 receive electrical signals from outside, they transmit a drive signal and a timing signal, etc., for controlling driving and a driving time of the liquid crystal panel assembly 130 to the data lines and the gate lines through the data TCP 135 and the gate TCP 133, respectively.
The color filter panel 131 includes red, green, and blue (“RGB”) color filters for displaying an image, through which light transmitted through liquid crystal in the liquid crystal layer formed between the color filter panel 131 and the TFT array panel 132 can appear in various colors. A common electrode (not shown) is formed on a front surface of the color filter panel 131. Thus, when a voltage is applied to the liquid crystal panel 137, an electric field is formed between the common electrode and the pixel electrode of the TFTs to change an arrangement of liquid crystals positioned there between.
While a particular arrangement of the LC panel assembly 130 has been illustrated and described, alternate arrangements of the LC panel assembly 130 are also within the scope of these embodiments.
The liquid crystal is a non-emissive element, that is, it cannot emit light, so the liquid crystal module 105 includes the backlight unit 145 for providing light to the liquid crystal panel 137. The backlight unit 145 is arranged to provide light from a lower side of the liquid crystal panel assembly 130, such as through the lower surface of the TFT array panel 132. The backlight unit 145 includes a cold cathode fluorescent lamp (“CCFL”) 155 for generating light and a light guide plate 150 for guiding light generated from the CCFL 155 to the liquid crystal panel 137. The backlight unit 145 further includes a lamp cover 151 surrounding the CCFL 155 to protect the CCFL 155 and to reflect light, which may not proceed directly to the light guide plate 150 after being emanated from the CCFL 155, towards the light guide plate 150. In the exemplary embodiment of the present invention, the CCFL 155 is positioned at the side of the light guide plate 150, but it can be also formed at a lower portion of the light guide plate 150. Also, although only one CCFL 155 is illustrated, the CCFL 155 may be provided in plural.
The light guide plate 150 is positioned at a lower side of the liquid crystal panel 137, has a size corresponding to the liquid crystal panel 137, and changes a path of light emitted from the CCFL 155 to guide it to the liquid crystal panel 137. While a particular arrangement of the CCFL 155 and light guide plate 150 have been illustrated and described, other arrangements of these elements would also be within the scope of these embodiments.
At an upper side of the light guide plate 150, there are provided a diffusion plate 141 for making luminance of light proceeding to the liquid crystal panel 137 uniform, and a plurality of optical sheets, and in the exemplary embodiment of the present invention, the diffusion plate 141 and a plurality of optical films 142 having a light collecting function or diffusion function are used. In the exemplary embodiment of the present invention, the diffusion plate 141 not only evenly distributes light provided from the backlight unit 145 but also absorbs light of a dummy wavelength range or noises, as will be further described below. As the plurality of optical films 142, a prism film for strengthening luminance upon collecting light or a film having a diffusion structure for diffusing light is used.
A reflector 160 is provided at a lower side of the light guide plate 150 in order to reflect light leaked from the light guide plate 150 and send the reflected light back toward the liquid crystal panel 137 to thus improve efficiency of light.
The liquid crystal panel assembly 130 and the backlight unit 145 are received in a bottom chassis 170, which is a receiving container and is fixedly supported by a molded frame 180. A bottom surface of the molded frame 180 is opened to expose a rear surface of the bottom chassis 170. Portions of the molded frame 180, where the data PCB 136 and the gate PCB 134 are bent to be mounted, are opened to allow circuit components mounted at the data PCB 136 and the gate PCB 134 to be smoothly received.
Although not shown in
A top chassis 120 is provided at an upper side of the liquid crystal panel assembly 130 in order to bend the data PCB 136 and the gate PCB 134 to the outside of the molded frame 180 and prevent the liquid crystal panel assembly 130 from being released from the bottom chassis 170. As the top chassis 120 and the molded frame 180 are combined with the front case 110 and the rear case 190, respectively, the LCD is formed.
In the graph shown in
The region A has a wavelength of 480±20 nm and the region A′ has a wavelength of 580±20 nm.
Namely, an LCD generally expresses color by combining the three colors of blue, green, and red, and in this case, when the CCFL is used as the light source, color reproducibility is degraded because of existence of a color besides the three colors blue, green, and red as shown in
In comparison, when the CCFL is used as the light source as shown in the right upper graph, light of unnecessary wavelengths such as at the regions A and A′ in
Based on the comparison, it can be observed that the CCFL has a smaller color region that can be expressed compared with the LED. In the left graph, National Television System Committee (“NTSC”) and European Broadcasting Union (“EBU”) indicate a color region expressed by a display device of each corresponding method. For example, Korea employs the NTSC method, so color reproducibility is commonly evaluated in Korea based on the color range expressed by the NTSC method.
It can be noted that, compared with the NTSC method, the LCD using the CCFL cannot cover many colors to represent them.
In order to solve the problem of the CCFL, in the present invention, a light absorption material 20 is included in the diffusion plate 141 of the LCD to absorb light of the regions A and A′ in
First,
In the present exemplary embodiment of the present invention, the light absorption material 20 is coated on the lower surface of the main body 10, but it can also be coated on an upper surface of the main body 10 that faces the optical film 142. Practically, however, it is more effective to coat the light absorption material 20 on the lower surface of the main body 10 than on the upper surface of the main body 10.
In the present exemplary embodiment of the present invention, for the light absorption material 20 for absorbing light of the region A having the wavelength 480±20 nm, a photochromic dye product, such as Reversacol™ Rush Yellow of James Robinson Ltd., was used. Meanwhile, for the light absorption material 20 for absorbing light of the region A′ having the wavelength of 580±20 nm, a photochromic dye product, such as Reversacol™ Flame of James Robinson Ltd., was used.
In the exemplary embodiment as shown in
The diffusion plate 141 according to the exemplary embodiment as shown in
The diffusion plate 141 according to the exemplary embodiment as shown in
The diffusion plate 141 according to the exemplary embodiment as shown in
Optical characteristics of the exemplary embodiments of the diffusion plate 141 will now be described.
The diffusion plate according to the exemplary embodiment in
First, in
With reference to
Comparatively, it is noted that the exemplary diffusion plate according to exemplary embodiments of the present invention, as indicated by curved line 2, allows light of the region A (having the wavelength of 480±20 nm) to be only slightly transmitted therethrough as shown in
While the graphs of
The wavelengths of 480±20 nm and 580±20 nm respectively represent dummy wavelength ranges.
As ascertained from the content of
This can be confirmed through an experimentation result obtained as shown in
That is, as shown in
Accordingly, in spite of using the CCFL, the color reproducibility can be improved by adding the light absorption material for absorbing light of an unnecessary wavelength to the diffusion plate 141.
Color reproducibility in the case of using the light absorption material for absorbing light of the region A (having the wavelength of 480±20 nm) and that in case of using the light absorption material for absorbing light of the region A′ (having the wavelength of 580±20 nm) will now be described.
In comparison of the curved lines ii and iii at the region A′ it is noted that intensity of the transmitted light is definitely reduced when the diffusion plate having the light absorption material is used. In particular, according to the present exemplary embodiment, at some portions, luminance of light was reduced by an amount of more than 50% when light was transmitted through the exemplary diffusion plate of the present invention. Consequently, although the CCFL is used, the color reproducibility can be enhanced by removing light of the unnecessary wavelength band.
In general, use of the CCFL in an LCD having a diffusion plate of the related art obtains color reproducibility remaining at some 72% compared with the NTSC method, whereas the color reproducibility can increase up to 80% in an LCD having an exemplary diffusion plate including the light absorption material according to the present invention.
In comparison of the curved lines v and vi at the region A (having the wavelength of 480±20 nm), it is noted that intensity of the transmitted light is definitely reduced when the exemplary diffusion plate having the light absorbing material of the present invention is used. In particular, according to the present exemplary embodiment, at some portions, luminance of light was reduced by a maximum 70% when light was transmitted through the exemplary diffusion plate of the present invention. Consequently, although the CCFL is used, the color reproducibility in the LCD can be enhanced by removing light of the unnecessary wavelength band.
In general, use of the CCFL in an LCD having a diffusion plate of the related art obtains color reproducibility remaining at some 72% compared with the NTSC method, whereas the color reproducibility can increase up to 78% in an LCD having an exemplary diffusion plate including the light absorption material according to the present invention.
As described above, because the light absorption material for absorbing a light of a dummy wavelength range or noises is added to a diffusion plate to remove light of an unnecessary wavelength band or bands in using the CCFL, the color reproducibility can be enhanced. In addition, using a film or developing a light source itself to improve color reproducibility would increase costs, but in the present invention, because the light absorption material is simply included in the diffusion plate, a fabrication or development cost can be reduced, and because a production line is not necessary, costs can be saved.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0094585 | Sep 2006 | KR | national |
