Fig. 1. Structure of direct-lit Mini-LED backlight module

Fig. 2. Mini-LED light source output situation

Fig. 3. Mixing light area division diagram

Fig. 4. Incidence of light in mixed light area

Fig. 5. Flow chart of lens design based on target plane illumination distribution

Fig. 6. Division of light source and target plane and corresponding relation between them. (a) Divide luminous flux of light source equally; (b) divide area of target plane according to illuminance distribution

Fig. 7. Schematic of design of double freeform surface lens

Fig. 8. 5×5 array simulation model of Mini-LED

Fig. 9. Illuminance distribution of target plane calculated by three methods

Fig. 10. Lens profiles obtained by three design methods. (a) Uniform distribution; (b) Gaussian distribution; (c) proposed method

Fig. 11. Simulated illumination distributions of lens at R=40mm. (a) Uniform distribution; (b) Gaussian distribution; (c) proposed method

Fig. 12. Calculation area of extended light source array simulation uniformity

Fig. 13. Illuminance distributions of target plane obtained under different R. (a) Gaussian distribution; (b) proposed method