To improve speedometer efficiency and visibility by concentrating light energy on meter scale.
Construction of speedometer
The speedometer consists of 3 main parts: a meter scale plate, light guide plate and holder. Each end of the LGP has an LED (shown in yellow). Note that only 2 LEDs are used to illuminate the whole speedometer.
Dot distribution in conventional design
In the conventional design of the speedometer, thousands of small white dots are printed on the entire LGP backface to achieve uniform illumination of the light-emitting face of the LGP.
Luminance distribution in conventional design
There is the loss of light energy in this design because the light emitted from a large part of the LGP is blocked and does not contribute to the output luminance. It shows the device efficiency of about 14%.
Dot distribution in improved design
The automatic design capability allows generation of any complex distribution of dots for optimization purpose. In this improved design, the LGP illuminates only the letters and scale to reduce the loss of light energy.
Luminance distribution by improved design
The visibility of the meter scale has been noticeably improved without spoiling the luminance uniformity. The device efficiency has increased to around 26%.
Construction of speedometer
Dot distribution in conventional design
Luminance distribution in conventional design
Dot distribution in improved design
Luminance distribution by improved design