1. Field of the Invention
The present invention relates to a display device and a method for manufacturing the same, and more particularly, to a display device with color filters used as electrodes which improves the color purity and optical efficiency of the display device and a method for manufacturing the same.
2. Description of the Background Art
Flat-panel display devices are generally classified into liquid crystal displays (LCD), field emission displays (FED), plasma display panels (PDP), and electroluminescence (EL).
Among those flat-panel display devices, the plasma display panel (PDP) being actively studied recently has a simple structure, is simply manufactured, has a higher brightness and luminous efficiency as compared to other flat-panel display devices, and can have an additional memory function. In addition, the PDP can implement a large-sized screen of more than 40 inches having a wide field angle of more than 160xc2x0. Therefore, the PDP having the above advantages has a potential of driving the flat-panel display market in the future.
When ultraviolet rays generated by gas, e.g., Hexe2x80x94Ne or Nexe2x80x94Xe, during plasma discharge within a discharge cell partitioned by partition walls excite red, green, and blue fluorescent materials formed on the partition walls, visible light generated when the excited fluorescent materials are transited to the ground state is emitted. Using this principle, the PDP displays characters and graphics by means of the emitted visible light. Meanwhile, the PDP is classified into an alternating current PDP (AC-PDP) and a direct current PDP (DC-PDP), said AC-PDP will now be described in more detail.
FIG. 1 is a structural diagram of the AC-PDP illustrating one cell in a general alternating plasma display panel (AC-PDP). The AC-PDP includes a front glass substrate 1 for displaying images, a back glass substrate 23 arranged in parallel to the front glass substrate 1 at a certain distance from the front glass substrate 1, and partition walls 13 positioned between the front glass substrate 10 and the back glass substrate 23 for forming a discharge space in the discharge cell in order to keep the distance between the front and back glass substrates constant and shut off electrical/optical interference between cells.
Here, the front glass substrate 1 further includes: an upper dielectric layer 3 for accumulating wall charges, keeping the discharge voltage, and protecting electrodes from ion bombardment and preventing the diffusion of ions during gas discharge; and a protective layer 9 formed on the surface of the upper dielectric layer 3 for protecting the upper dielectric layer 3 from sputtered plasma particles to thereby lengthen the life span thereof, increasing the relatively high efficiency of the emission of secondary electrons when a low ion energy is bumped against the surface during plasma discharge, and reducing the amount of changes in the discharge characteristics of refractory metals by means of oxides. At this time, the protective layer 9 is mainly made of magnesium oxide (MgO).
In addition, the upper dielectric layer 3 includes a sustain electrode 5, a transparent electrode, made of Indium Tin Oxide (ITO) and a bus electrode 7 made of metal which is connected with the sustain electrode 5.
The back glass substrate 23 includes an address electrode 19 for occurring discharge of the sustain electrode 5 and the bus electrode 7, an under layer 21 for attaching the address electrode 19 and the back glass substrate 23, a lower dielectric layer 17 for covering the address electrode 19, and a fluorescent material 15 for covering the lower dielectric layer 17 and the partition walls 13 formed thereon and generating visible light.
In addition, a black top 11 for absorbing light incident from the outside through the front glass substrate 1 is connected to the upper portion of the wall partition 13.
In the thusly constructed PDP, a discharge is initiated between the address electrode 19 and the sustain electrode 5, in a state that the inner space of the discharge cell is filled with a discharge gas, for example, a gas mixture of Hexe2x80x94Ne and Nexe2x80x94Xe. When the discharge is continuously maintained between the sustain electrodes 5, vacuum ultraviolet (VUV) rays with a wavelength of 147 mm are emitted. Then, the vacuum ultraviolet rays excite the fluorescent material 15. When the fluorescent material 15 is transited from the excited state to the ground state, red, green, and blue visible light is emitted and accordingly desired images are displayed through the front glass substrate 1.
Among the flat-panel display devices, the electroluminescence (EL) are active display devices using the phenomenon that the fluorescent material becomes luminescent by applying an electric field to a conductive fluorescent material coated on a glass substrate or a transparent organic film, which are divided into thin film electroluminescent devices (TFEL), dispersion type electroluminescent devices (EL), and solid state displays (SSD) which are fabricated by improving the thin film electroluminescent devices, said solid state display will now be described in more detail.
FIG. 2 is a structural diagram of a general solid state display, in which a back glass substrate 31, a back electrode 32 formed on the back glass substrate 31, a thick film dielectric layer 33 formed on the back glass electrode 32 for preventing dielectric breakdown, a fluorescent layer 35 formed on the thick dielectric layer 33 for generating visible rays, a thin film dielectric layer 36 formed on the fluorescent layer 35, and a transparent electrode 37 formed on the thin film dielectric layer 33 are stacked one after another. In addition, a planarization layer 34 for planing the interface between the thick film dielectric layer 33 and the fluorescent layer 35 is further stacked between the thick film dielectric layer 33 and the fluorescent layer 35.
The driving principle of the thusly constructed SSD will now be described in brief.
Firstly, when a predetermined voltage (e.g., 22 V) is applied to the back electrode 32 and the transparent electrode 37, electrons are emitted at the interface level of the thick film dielectric layer 33 and the thin film dielectric layer 36 adjacent to the fluorescent layer 35 by means of a tunneling effect. The emitted electrons are accelerated by a high electric field (e.g., 106 V/m) to turn into thermal electrons. The thermal electrons collide with atoms contained in the fluorescent material (e.g., ZnS:Mn) and as a result these atoms become excited. The excited atoms emit visible rays while transiting to the ground state. By this principle, the solid state display displays desired images.
Furthermore, the thick film dielectric layer 33 serves to prevent dielectric breakdown and diffusion between the back electrode 32 and the fluorescent layer 35, stably supply a high voltage, and keep the solid state display""s thermal stability.
The PDP and SSD cited among the flat-panel display devices implement all kinds of colors by emitting the corresponding light from red, green, and blue fluorescent materials contained in each cell of the PDP and SSD. However, there occurs a problem that the color purity is reduced due to the phenomenon that colors emitted from the fluorescent materials are mixed with one another. To solve the above problem, color filters are attached on the front glass substrate, said color filters emit the respective colors corresponding to the fluorescent materials for thereby increasing the color purity.
However, in order to increase the color purity, the color filters attached on the front glass substrate of the PDP and SSD still have a problem of decreasing the brightness of the light emitted from the PDP and SSD, as compared to the brightness of the light emitted from the PDP and SSD having no color filter attached on the front glass substrate.
Accordingly, it is an object of the present invention to provide a display device with color filters used as electrodes for improving the purity of colors displayed by the display device and increasing the optical efficiency.
It is another object of the present invention to provide a method for manufacturing a display device with color filters used as electrodes for improving the purity of colors displayed by the display device and increasing the optical efficiency.
To achieve the above objects, a display device with color filters used as electrodes in accordance with the present invention is formed by forming conductive color filters on an upper substrate.
In the display device with color filter used as electrodes in accordance with the present invention, the color filter is made of a conductive material.
A plasma display panel with color filters used as electrodes in accordance with the present invention is formed by including pairs of sustain electrodes on a back glass substrate and forming color filters used as address electrodes on an upper substrate.
A solid state display device with color filters used as electrodes in accordance with the present invention is formed by forming a back electrode formed on a back glass substrate and color filters on an upper substrate.
A method for manufacturing a display device with color filters used as electrodes in accordance with the present invention includes the steps of preparing a conductive color filter material and forming red, green, and blue filters out of the conductive color filter material.
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