Projection lens assembly

1. A projection lens assembly comprising, sequentially along an optical axis from an image-source side to an image side,

a first lens having a positive refractive power or a negative refractive power;

a second lens having a positive refractive power or a negative refractive power; and

a third lens having a positive refractive power, wherein an image-side surface of the third lens is a convex surface;

wherein a distance TTL on the optical axis from an image-source plane of the projection lens assembly to the image-side surface of the third lens and a total effective focal length f of the projection lens assembly satisfy: TTL/f<1.4, and

an effective focal length f3 of the third lens and the total effective focal length f of the projection lens assembly satisfy: 0<f3/f<18.0,

wherein the projection lens assembly has and only has three lenses having refractive power,

wherein half of a maximal field-of-view HFOV of the projection lens assembly satisfies: HFOV≤8.4°, and

wherein a distance BF on the optical axis from the image-source plane of the projection lens assembly to an image-source-side surface of the first lens and the distance TTL on the optical axis from the image-source plane of the projection lens assembly to the image-side surface of the third lens satisfy: 0.16≤BF/TTL<0.5.

2. The projection lens assembly according to claim 1 , wherein a center thickness CT1 of the first lens on the optical axis and a center thickness CT2 of the second lens on the optical axis satisfy: 1.3<CT1/CT2<1.8.

3. The projection lens assembly according to claim 1 , wherein a radius of curvature R6 of the image-side surface of the third lens and the total effective focal length f of the projection lens assembly satisfy: −0.5<R6/f<0.

4. The projection lens assembly according to claim 1 , wherein a spacing distance T12 on the optical axis between the first lens and the second lens and a center thickness CT3 of the third lens on the optical axis satisfy: 0.1<T12/CT3<0.8.

5. The projection lens assembly according to claim 1 , wherein an effective semi-diameter DT22 of an image-side surface of the second lens and an effective semi-diameter DT21 of an image-source-side surface of the second lens satisfy: 1.0<DT22/DT21<1.5.

6. The projection lens assembly according to claim 1 , wherein an effective semi-diameter DT32 of the image-side surface of the third lens and an effective semi-diameter DT31 of an image-source-side surface of the third lens satisfy: 1.0<DT32/DT31<1.3.

7. The projection lens assembly according to claim 1 , wherein a light transmittance of the projection lens assembly is greater than 85% within a light wavelength range from 800 nm to 1000 nm.

8. A projection lens assembly comprising, sequentially along an optical axis from an image-source side to an image side,

a first lens having a positive refractive power or a negative refractive power;

a second lens having a positive refractive power or a negative refractive power; and

a third lens having a positive refractive power, wherein an image-side surface of the third lens is a convex surface;

wherein a distance TTL on the optical axis from an image-source plane of the projection lens assembly to the image-side surface of the third lens and a total effective focal length f of the projection lens assembly satisfy: TTL/f<1.4, and

an effective focal length f3 of the third lens and an effective focal length f1 of the first lens satisfy: −1.0<f3/f1<30.0,

wherein the projection lens assembly has and only has three lenses having refractive power,

wherein a distance BF on the optical axis from the image-source plane of the projection lens assembly to an image-source-side surface of the first lens and the distance TTL on the optical axis from the image-source plane of the projection lens assembly to the image-side surface of the third lens satisfy: 0.16<BF/TTL<0.5, and

wherein a center thickness CT1 of the first lens on the optical axis and a center thickness CT2 of the second lens on the optical axis satisfy: 1.3<CT1/CT2<1.8.

9. The projection lens assembly according to claim 8 , wherein an effective semi-diameter DT22 of an image-side surface of the second lens and an effective semi-diameter DT21 of an image-source-side surface of the second lens satisfy: 1.0<DT22/DT21<1.5.

10. The projection lens assembly according to claim 8 , wherein an effective semi-diameter DT32 of the image-side surface of the third lens and an effective semi-diameter DT31 of an image-source-side surface of the third lens satisfy: 1.0<DT32/DT31<1.3.

11. The projection lens assembly according to claim 8 , wherein the effective focal length f3 of the third lens and the total effective focal length f of the projection lens assembly satisfy: 0.5<f3/f<1.6.

12. The projection lens assembly according to claim 11 , wherein a radius of curvature R6 of the image-side surface of the third lens and the total effective focal length f of the projection lens assembly satisfy: −0.5<R6/f<0.

13. The projection lens assembly according to claim 8 , wherein a spacing distance T12 on the optical axis between the first lens and the second lens and a center thickness CT3 of the third lens on the optical axis satisfy: 0.1<T12/CT3<0.8.

14. The projection lens assembly according to claim 8 , wherein half of a maximal field-of-view HFOV of the projection lens assembly satisfies: HFOV<10°.

15. The projection lens assembly according to claim 8 , wherein a light transmittance of the projection lens assembly is greater than 85% within a light wavelength range from 800 nm to 1000 nm.