Projection Lens
The present disclosure discloses a projection lens. The projection lens includes, from an object side to an image side in sequence: an object surface, a first lens with a positive refractive power, a second lens with a negative refractive power, and a third lens with a positive refractive power. The projection lens further satisfies the following conditions: 0.95≤f/TTL≤2; 0.22≤Te/TTL≤0.3; where f: focal length of the projection lens; TTL: the total distance from the object side surface of the first lens to the image plane along the optic axis; Te: distance from the object surface to an edge of the first lens.
1 . A projection lens comprising, from an object side to an image side in sequence: an object surface, a first lens with a positive refractive power, a second lens with a negative refractive power, a third lens with a positive refractive power; wherein the projection lens further satisfies the following conditions:
0.95≤ f/TTL≤ 2;
0.22≤ Te/TTL≤ 0.3;
where
f: focal length of the projection lens;
TTL: the total distance from the object side surface of the first lens to the image plane along the optic axis;
Te: distance from the object surface to an edge of the first lens.
2 . The projection lens as described in claim 1 further satisfying the condition:
TTL≤ 3.2 mm.
3 . The projection lens as described in claim 1 further satisfying the condition:
3.3 mm≤ f≤ 4.5 mm.
4 . The projection lens as described in claim 3 further satisfying the condition:
3.6 mm≤ f≤ 3.8 mm.
5 . The projection lens as described in claim 1 further satisfying the condition:
0.7 mm≤ Te≤ 0.9 mm.
6 . The projection lens as described in claim 1 further satisfying the condition:
0.5≤ f 3/ f 1≤2;
where
f1: focal length of the first lens;
f3: focal length of the third lens.
7 . The projection lens as described in claim 1 further satisfying the condition:
1≤ d 5/ d 3≤3; where
d3: thickness of the second lens on optic axis;
d5: thickness of the third lens on optic axis.
8 . The projection lens as described in claim 1 further satisfying the condition:
−6≤ f/R 6≤0; where
R6: curvature radius of an image side surface of the third lens.
9 . The projection lens as described in claim 1 further satisfying the condition:
−3≤ R 1/ R 6≤0; where
R1: curvature radius of an object side surface of the first lens;
R6: curvature radius of an image side surface of the third lens.
10 . The projection lens as described in claim 1 further satisfying the condition:
−0.00001<( dn/dt )1<0; where
dn/dt: change rate of refractive index of the first lens made of glass according to the change of temperature.
11 . The projection lens as described in claim 1 , wherein the second lens is made of plastic, and the third lens is made of plastic.