我家也是3米，买的SONY的55HX750   55寸的

第一天看就晕了，三天后没任何感觉了，现在觉得挺好的。  

我后来还看到这个
http://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance

Manufacturers' recommendations
Range recommendations from manufacturers are the most modest of the groupings. For the minimum (or nearest) viewing distance, they recommend a view angle of approximately 31 degrees; and for the maximum, a view angle as low as 10 degrees.[33][34] A 10 degree view angle is approximately the angle that NTSC television was typically viewed from.[36]
RCA
Screen Size    Recommended Range
22"    3'0" – 8'4" (0.9 – 2.5 m)
26"    3'5" – 9'10" (1.0 – 3.0 m)
32"    4'4" – 12'1" (1.3 – 3.7 m)
40"    5'4" – 15'1" (1.6 – 4.6 m)
42"    5'5" – 15'10" (1.7 – 4.8 m)
52"    6'0" – 17'0" (1.8 – 5.2 m)
TOSHIBA
Screen Size    Recommended Range
19"    2.5' – 8.0' (0.7 – 2.4 m)
22"    3.0' – 9.0' (0.9 – 2.7 m)
26"    3.5' – 10.5' (1.0 – 3.1 m)
32"    4.0' – 13.0' (1.2 – 4.0 m)
37"    4.5' – 15.0' (1.3 – 4.6 m)
40"    5.0' – 16.5' (1.5 – 5.0 m)
42"    5.5' – 17.5' (1.6 – 5.3 m)
46"    6.0' – 19.0' (1.8 – 5.8 m)
52"    6.5' – 21.5' (1.9 – 6.5 m)
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