Patent ID: 7075622

Claim:
A fixed-focus projection lens, consisting of: six lenses, the six lenses including a single lens having negative refracting power serving as a first lens, a single lens having positive refracting power serving as a second lens, a single lens having negative refracting power serving as a third lens, a compound lens having positive refracting power, consisting of a first component lens having negative refracting power and a second component lens having positive refracting power and cemented to the first component lens, and serving as a fourth lens, and a single lens having positive refracting power serving as a fifth lens, the six lenses being arranged in that order from a side of a screen toward a display device; wherein a part of the projection lens on the side of the display device is substantially telecentric, and a surface, on the side of the display device, of the first lens, and a surface, on the side of the display device, of the second component lens of the fourth lens are aspherical, wherein 0.3<L 23 /L 2-4 <0.5, where L 2-4 is the distance between an end, on the side of the screen, of the second lens and an end, on the side of the display device, of the fourth lens, and L 23 is the distance between an end, on the side of the display device, of the second lens and an end, on the side of the screen, of the third lens, and wherein the first, the second and the third lens meet a condition: âˆ’1.5<f 1-2 /f 3 <âˆ’0.8, where f 1-2 is the synthetic focal length of the first and the second lens, and f 3 is the focal length of the third lens.