Patent Application
20070285790
The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which:
Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.
Certain embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings.
In the following description, same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention can be carried out without those defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the understanding of the invention.
Referring to
The lower substrate 110 is a glass substrate, and a plurality of address electrodes 111 generating an address discharge are arranged in stripes on the upper surface of the tower substrate 110. A first dielectric layer 112 is formed on the upper surface of the lower substrate 110 to cover the address electrodes 111. The first dielectric layer 112 may be formed by applying a white dielectric material onto the upper surface of the lower substrate 110.
A plurality of partitions 113 are provided at a predetermined interval on the upper surface of the first dielectric layer 112. The partitions 113 are arranged in parallel with the address electrodes 111. The partitions 113 define the space between the lower substrate 110 and the upper substrate 120 to form the discharge cells 115 and simultaneously prevent electrical or optical crosstalk among adjacent discharge cells 115. Consequently, the partitions 113 serve to improve color purity. Red (R), green (G), and blue (B) fluorescent layers 114 having a predetermined thickness are coated on the upper surface of the first dielectric layer 112 and the sidewalls of the partitions 113 which form the inner surfaces of the respective discharge cells 115.
The discharge cells 115 are filled with a discharged gas which is generally a mixture of Ne and Xe, to generate the plasma discharge. The fluorescent layers 114 are excited by the UV rays generated due to the plasma discharge of the discharged gas, and thus emit visible rays of light having a color corresponding to the respective fluorescent layers 114.
On the lower surface of the upper substrate 120, discharge electrodes 121a and 121b are provided in stripes in a direction perpendicular to the address electrodes 111. As shown in
Bus electrodes 122a and 122b made of metal are provided on the lower surfaces of the discharge electrodes 121a and 121b, and the bus electrodes 122a and 122b make a pair, like the discharge electrodes 121a and 121b. The bus electrodes 122a and 122b are electrodes to reduce the line resistance of the discharge electrodes 121a and 121b, and have a width narrower than that of the discharge electrodes 121a and 121b.
A second dielectric layer 123 is formed to cover the discharge electrodes 121a and 121b and the bus electrodes 122a and 122b. The second dielectric layer 123 may be formed by applying a transparent dielectric material onto the lower surface of the upper substrate 120 to have a predetermined thickness. A protective layer 124 is formed on the lower surface of the second dielectric layer 123, and serves to prevent the second dielectric layer 123 and the discharge electrodes 121a and 121b from damaged due to sputtering of plasma particles and also to reduce discharge voltage by emitting secondary electrons. The protective layer 124 is formed by applying magnesium oxide (MgO) onto the lower surface of the second dielectric layer 123 with a predetermined thickness.
With the above arrangement of the plasma display panel, the address discharge is generated between the address electrode 111 and either of the discharge electrodes 121a and 121b. During this address discharge, a wall charge is formed. When AC voltage is applied to the pair of the discharge electrodes 121a and 121b, the sustaining discharge is generated in the discharge cells 115 with the wall discharge formed thereon, and thus UV rays are generated from the discharged gas. The fluorescent layer 114 is excited by the UV rays to emit visible rays of light.
A near-infrared filtering part 125 is formed on the upper surface of the upper substrate 120 to filter or interrupt near infrared rays slightly longer than visible rays of light generated from the discharge cell 115 and improve color purity. Further, an optical part 126 is formed on the upper surface of the near-infrared filtering part 125, and has a light guide 126a collecting and emitting the visible rays of light, from which the near infrared rays are filtered, and an external light filtering member 126b preventing external light from entering the discharge cells 115.
The light guide 126a includes a light incident surface, on which visible rays of light generated from the discharge cells 115 are incident, and a light emitting surface. The light incident surface has an area larger than that of the light emitting surface. The visible rays of light are radiated into the light guide 126a through the light incident surface, and are emitted from the light emitting surface. Since the light guide 126a can be formed with a width of up to several tens of μm, it is used to form a high precise image, thereby improving the luminance of the panel. The external light filtering member 126b is made of a mixture of carbon black and a medium having a low index of reflection. Accordingly, the external light filtering member 126b absorbs light entering from the exterior to prevent contrast from being reduced due to the external light.
On the upper surface of the optical part 126, an EMI shielding part 127 shielding an electromagnetic interference (EMI) is formed in a mesh shape or as a conductive film. Further, an anti-reflection part 128 preventing reflection of external light is formed on the upper surface of the EMI shielding part 127. An anti-reflective film may be used as the anti-reflection part 128.
As described above, by the elements 125, 126, 127, and 128 formed on the upper surface of the upper substrate 120, the visible rays of light generated from the discharge cells 115 are filtered, collected, and emitted, and also the influence of external light is minimized, whereby improving the bright room contrast.
As such, the elements 125, 126, 127, and 128 formed on the upper surface of the upper substrate 120 may be formed as a film so that it can be adhered on the upper substrate 120.
In general, when light is incident at a certain angle from a medium having a high index of reflection to a medium having a low index of reflection, total internal reflection (TIR) takes place at the boundary between two mediums when the angle of incidence is greater than a specified threshold angle. The light guide 126a collects and emits the visible rays of light generated from the discharge cells 115 with use of the feature in that the total amount of the incident light is reflected at the boundary, as described above.
Referring to
θ=arc sin (Na/Nf) (1)
In Equation (1), Na denotes an index of reflection of the external light filtering member 126b, and Nf denotes an index of reflection of the light guide 126a.
Table 1 shows the relationship between the luminance and the incident angle α depending on the viewing angle β depicted in
As shown in Table 1, the luminance of the diffused light and the incident angle α entering the boundary F are varied depending on the viewing angle β. That is, as the viewing angle β is increased, the luminance of the diffused light is decreased, and the incident angle α is also reduced.
Supposing that the index of reflection of the external light filtering member 126b is 1.4, the threshold angle θ of the visible rays of light generated from the discharge cells 115 is calculated at about 63.8° through Equation 1. Therefore, the light having the incident angle α of above 63.8° is wholly reflected from the light guide 126a, and is emitted toward the emitting surface O. That is, referring to Table 1, the diffused light having a viewing angle of about −23° to +23° satisfies the condition of total reflection.
The construction of the plasma display panel 200 shown in
The filter 300 provided on the upper surface of the plasma display panel 200 includes a near-infrared filtering part 310, an optical part 320, an EMI shielding part 330, a glass substrate 340, and an anti-reflection part 350.
The near-infrared filtering part 310 is to filter or interrupt near infrared rays slightly longer than visible rays of light generated from the discharge cell 215 and improve the color purity.
The optical part 320 includes a light guide 321 and an external light filtering member 322. The light guide 321 is to collect and emit the visible rays of light generated from the discharge cells 215. The light incident surface of the light guide 321 has an area larger than that of the light emitting surface. Since the light guide 321 can be formed with a width of up to several tens of μm, it is used to form a high precise image, thereby improving the luminance of the panel. The external light filtering member 322 is made of a mixture of carbon black and a medium having a low index of reflection.
The EMI shielding part 330 is to shield an electromagnetic interference (EMI), and is formed in a mesh shape or as a conductive film. The filter 300 has a glass substrate 340 to reinforce its rigidity. The glass substrate 340 used in the filter is a tempered glass, and minimizes the generation of corrugation on the filter 300. The anti-reflection part 350 is to prevent reflection of the external light, and an anti-reflective film may be used as the anti-reflection part 350.
By providing the plasma display panel 200 with the film 300, the visible rays of light generated from the discharge cells 215 are filtered, collected, and emitted, and also the influence of external light is minimized, thereby improving the bright room contrast.
As described above, according to the present invention, by reforming the construction of the upper substrate of the plasma display panel or providing the plasma display panel with the improved filter, the bright room contrast can be improved or a fine quality of an image can be provided to a user.
The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-51010 | Jun 2006 | KR | national |
