A generalized model for luminance prediction in a bottom-lit backlight with cold cathode fluorescent lamps

This paper proposes a generalized model to predict the luminance of a bottom-lit backlight based on analytical estimates of the luminous flux input provided by a cold cathode fluorescent lamp (CCFL). The respective influences of the CCFL half-angle, the CCFL luminance decay factor, the luminance cone angle ratio and the luminance peak offset are discussed. The analytical results reveal that the CCLF half-angle has a more significant effect on the luminous flux and the backlight luminance than the CCFL luminance decay factor. In addition, when the luminance cone angle ratio is adjusted by changing the cone angle in one direction while maintaining the cone angle in the other as a constant, the luminance level is found to be higher when the luminance distribution has a circular cross section at the half-luminance peak rather than an elliptical cross section. Conversely, when the luminance cone angle ratio is adjusted under the condition that the cross-sectional area of the luminance distribution at the half-luminance peak remains constant, the luminance level is found to be higher for an elliptical cross section than for a circular cross section. Finally, the luminance level decreases more rapidly in a specific direction if the luminance cone angle in this direction is smaller than that in the other and the luminance peak offset increases coincidently in the same direction.