Projection lens unit

Details Projection lens unit Projection lens unit

2006-10-24

2006-10-24

Mack, Ricky (Department: 2873)

Optical: systems and elements

Lens

With support

C359S815000, C359S819000, C359S822000, C359S823000

Reexamination Certificate

active

07126768

ABSTRACT:
A projection lens unit includes a main body; a lens fixed to the main body; and a hood disposed to one end of the main body close to a screen. The hood defines the outermost boundary of a view angle stretching with respect to the center of the lens and includes a light-shielding plate and a light-shielding barrel. When the shielding height of the light-shielding plate and the length of the light-shielding barrel are respectively represented by H and L, the shielding height H and the length L are set so as to satisfy the equation tan(α/2)=H/L, in relation to the view angle α. More particularly, these dimensions are set so as to satisfy the condition that the ratio H/L lies in a range from 0.74 to 0.94. The inner surface of the light-shielding barrel is subjected to surface treatment so as to absorb unnecessary light thereby, reflect it thereat, or scatter it thereat. To be more specific, the light-shielding barrel has scattering grooves disposed on the inner surface thereof.

REFERENCES:
patent: 6425667 (2002-07-01), Haba et al.
patent: 2004/0061947 (2004-04-01), Fujisawa et al.
patent: 2004/0212904 (2004-10-01), Sekine et al.
patent: 2005/0117900 (2005-06-01), Ohmori et al.
patent: 2000-194065 (2000-07-01), None
patent: 2002-040310 (2002-06-01), None
patent: 2002-202451 (2002-07-01), None
patent: 2003-270506 (2003-09-01), None
patent: 2004-054044 (2004-02-01), None

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