Estimate luminance of single panel and dual panel light guide by luminous flux flow

Abstract

This paper presents a mathematical method to estimate luminous flux and luminance of single panel and dual panel light guides based on photometric calculations under various design requirements. The distribution of dot pattern or micro-prism was computed according to those estimated luminous flux on the illuminant surface. The effects of light source efficiency, angular distribution of luminance of light guide, luminous flux ratio and area ratio of main panel with sub panel on luminance of light guide are discussed. The relationship between luminous flux and luminance was derived for single panel and dual panel light guides. For single panel light guide, the result reveals that the angular distribution of luminance of light guide affects the luminance obviously. The luminance increases as the cone angle (the range of angular distribution of luminance) decreases. For dual panel light guide, the luminous flux of three different areas, two located at main panel and one located at sub panel, are the functions of angular distribution, luminous flux ratio and area ratio. The luminance of main panel and sub panel were estimated and computed from mathematical functions. The optical properties of dot pattern and micro prism or other optical objects were used to determine the luminous flux ratio and then the difference luminance between main panel and sub panel was estimated. This estimation strategy provides a fast initial design and the solution to predict the luminance of single panel and dual panel of light guide.

Feasibility study of edge-lit backlight of dual-panel display by a simple configuration model

“…The luminous flux provided by each LED is found to be 1.557 lm (=U in /3) and is derived by integrating the relative luminous intensity distribution (given in the LED specification) over the spherical space [5]. The main panel area, i.e.…”

“…This problem is evident in many dual-display backlights, in which it is commonly observed that the area of the main panel corresponding to the position of the sub-panel is darker than the remaining panel area [4]. Furthermore, the optical design must not only ensure that both panels are evenly illuminated, but must also maintain the specified luminance difference between the main panel and the sub-panel [5]. Therefore, achieving the specified luminance conditions for the dual-panel display requires a knowledge of the optimum design specifications for the related optical elements, i.e.…”

Photometric quantity analysis of backlight for a dual-panel display

“…This causes the region of the main panel corresponding to the position of the subpanel to be darker than the remaining main panel area since this particular region of the main panel receives relatively less luminous flux than the surrounding area. 10 In addition, a further design difficulty is the necessity to deliver an even luminance of the subpanel irrespective of whether its luminance is to be smaller than, greater than, or equal to that of the main panel. The structural layout of a dual-panel backlight is more complicated than that of a single-panel backlight, and hence it is difficult to know before entering the detailed design phase whether or not the design specifications for the luminance of the main panel and the subpanel can actually be attained.…”

“…6 The aim of the light guide design for a dual-panel backlight system is to ensure an appropriate allocation of the received luminous flux between the main panel and the subpanel in order to attain an equal luminance of the two panels. 10 In practice, most light guides are flawed in that their diffuser dot density patterns. 10 tend to direct too much luminous flux flow downward to the subpanel.…”

“…10 In practice, most light guides are flawed in that their diffuser dot density patterns. 10 tend to direct too much luminous flux flow downward to the subpanel. This causes the region of the main panel corresponding to the position of the subpanel to be darker than the remaining main panel area since this particular region of the main panel receives relatively less luminous flux than the surrounding area.…”