1. Moiré Interference In Multilayered Display Gareth Bell, PureDepth Inc., Journal of SID07 Moiré Interference In Multilayered Display Gareth Bell, PureDepth Inc., Journal of SID07 Speaker: Yu-Chen Chang ( 張育誠 ) Advisor: Prof. Yi-Pai Huang( 黃乙白教授 ) Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan December 13 2007

2. 2 Advanced Display Optics Lab Outline  Introduction  Theoretical model of moiré interference  Experimental method  Results  Conclusions

3. 3 Advanced Display Optics Lab Introduction – Multi-layered display(MLD) MLD ： contain at least two displays Key issue ： Moiré Period of Moiré

4. 4 Advanced Display Optics Lab Solution of Moiré Common solution ： adding a diffuser layer between display Image blur To optimize display, Moiré and Blur should be minimized !!! MLD in Fourier space

5. 5 Advanced Display Optics Lab Outline  Introduction  Theoretical model of moiré interference  Experimental method  Results  Conclusions

6. 6 Advanced Display Optics Lab Concept of Model Considerable factors ： Basic period for Moiré Affecting rear display Tri-stimulus value of human eyes Other period Pixel array, Diffuser, Color combination, Uniformity of BL, …etc.

7. 7 Advanced Display Optics Lab Expression for the effect of a filter with a particular BTDF on image diffuser backlight ω0ω0 dA ωiωi Diffuser ： The BTDF of any surface is Assuming the flux at any point is constant, the luminance becomes PSF ： On-axis  indep. on viewing angle The worst case  foveal vision

8. 8 Advanced Display Optics Lab General expression for Moiré interference For different pixel schemes Color combination Vector of rear and front display p N ： a pixel Final image span p 1 span p 2 position

9. 9 Advanced Display Optics Lab General expression for Moiré interference Transferring to Fourier space Amplitudes for etch tri-stimulus ：

10. 10 Advanced Display Optics Lab Outline  Introduction  Theoretical model of moiré interference  Experimental method  Results  Conclusions

11. 11 Advanced Display Optics Lab Experimental method Predict Moire Estimate the distance to eliminate morie Move diffuser Measure moire v.s. distance Display test image See spatial freq. v.s. distance Process ： Apparatus ： diffuser Distance ： 0.1~3mm

12. 12 Advanced Display Optics Lab Measure for Moiré and for blur Measuring MoiréMeasuring blur Backlight Rear display Front display Diffuser layer Camera

13. 13 Advanced Display Optics Lab Outline  Introduction  Theoretical model of moiré interference  Experimental method  Results  Conclusions

14. 14 Advanced Display Optics Lab Results -- Moiré Parameters ： Results ： CCD image of Moiré ： Ratio = 8.15 Horizontal amp. decreases to ~4% Distance Moiré

15. 15 Advanced Display Optics Lab Results -- blur 0 cm 2 cm 10 cm Blur v.s. distance ： Distance Blur

16. 16 Advanced Display Optics Lab Outline  Introduction  Theoretical model of moiré interference  Experimental method  Results  Conclusions

17. 17 Advanced Display Optics Lab Conclusions  This new model that is described in the Fourier domain is useful for any pixel pattern.  Distance Moiré and blur  Horizontal amplitude is decreased to 4% after adding diffuser layer.

18. 18 Advanced Display Optics Lab

19. 19 Advanced Display Optics Lab SQRI