Ko Sano

Mechanical and electrical properties of rf sputtered LaB6 thin films on glass substrates

Abstract LaB 6 films from 2000 to 5000 A thick were prepared on glass substrates by rf magnetron sputtering. The effects of Ar discharge gas pressure from 5.3 to 5.3 × 10 −2 Pa on the structural, electrical and mechanical properties of the films were examined. The structural characteristics were analyzed by X-ray diffraction and emission spectrochemical technique (ICP). The electrical film resistivity was measured using a four-point probe technique. The internal stress and adhesion of films were determined by the bending-plate method and the microtribometer, respectively. The deposition process of rf magnetron sputtering was studied by a quadrupole mass filter system. The results indicated that an increase in Ar gas pressure in sputtering depositions increased the atomic ratio B/La in LaB films. The most preferable Ar gas pressure for stoichiometric LaB 6 formation was found to 10 −1 Pa and it was also suitable for producing high quality films as electrodes. The main crystalline orientation of the sputtered LaB 6 films was (100) which is the orientation of lower work function (2.4–2.5 eV) in LaB 6 crystals.

Improvement in luminance, luminous efficiency, driving margin, and operational lifetime of HD PDPs by using discharge deactivation film

— We have improved our 116-cm HD PDP in many respects by using DDF formed on MgO around the display line boundaries. The DDF allows an extremely narrow inter-pixel gap even for a stripe-rib structure because it prohibits vertical crosstalk discharge. The DDF combined with a stripe-rib structure results in the best address discharge response. Thus, a very wide driving margin area is achieved, allowing for a high percentage of Xe. The preferable sustain electrode shape follows the CAPABLE DDF style, where the principal discharge portion is separated from the bus via a slim bridge. This cell configuration proved to be excellent in operational life testing with respect to DDF as well as in manufacturing process margin. By employing both a thinner dielectric layer and a TiO2reflective underlayer for phosphor, the address response is further improved so that Xe15% vol. is available from the viewpoint of the driving margin. Thus, we achieved a white peak luminance of 1220 cd/m2 and a luminous efficiency of 2.16 lm/W simultaneously despite of an applied sustain voltage as low as 185 V. We foresee that they will be soon as high as 1400 cd/m2 and 2.5 lm/W by modifying the sustain electrode style.

DIA-PDP with high luminous efficacy and increased vertical resolution

— A PDP utilizing a new cell configuration to improve the vertical resolution and luminous efficacy is proposed. In this configuration, a delta subpixel arrangement is adopted because it reduces the vertical pixel pitch by half and increases the vertical resolution. In this configuration, R, G, B subpixels form triangles which are diamond shaped, the rational for calling this technology “DIAPDP.” High luminous efficacy is achieved by reducing the reflectivity of the panel. The lower reflectivity enables increased transmittivity of the light-reduction filter which is part of the PDP panel, thus ensuing sufficient contrast under bright conditions. The higher transmittivity increases the luminous efficacy with the filter. Results obtained for a 46-in. panel demonstrate a 33% increase in the luminous efficacy when using the filter. The DIA cell configuration is further modified to be a “clustered DIA” in order to improve the color mixing. Through subjective evaluation, the color mixing was compared with that of panels based on a trio subpixel arrangement and DIA, and the effect on color mixing was confirmed. The luminous efficacy of clustered DIA is also shown to be equal to that of DIA.

Material and Manufacturing Process Technologies of Discharge Deactivation Film for Stripe Rib PDPs

We developed material and process technologies concerned to DDF, which is formed on MgO surface around the inter-pixel gap to prevent vertical crosstalk discharge in stripe rib structure. First we tried with thin film deposition and lift-off patterning to find Al 2 O 3 and TiO 2 are both available for DDF material. Next we tried with thick film printing in favor of mass productivity for large size PDPs. In case DDF included PbO glass, we met serious hardship in generating discharge. The problem was perfectly solved by having thick film DDF composed of 100 nm sized Al 2 O 3 grains without glass component. Its γ i was about 1/5 that of MgO, suggesting that the thick film DDF is almost compatible with thin film Al 2 O 3 in electron emission characteristics. Such very small grain size contributes to DDF transparency, which is excellently high. In addition to it, such DDF is equipped with cushioning effect to prevent dot defects caused by rib breakage. Furthermore the DDF functions as getter during panel exhaustion to bring deep blue color by promoting deoxidization of blue phosphor provided that its volume is small enough. Transparent DDF may be rather better than black one with respect to bright room contrast ratio, not to mention to avoiding terrible sparking discharge. Thus material and process technologies for DDF have been almost fixed in success.