TWM508677U - Zooming projection lens - Google Patents

Description

Zoom projection lens (1)

This creation is related to projection lenses; in particular, a zoom projection lens.

In recent years, with the advancement of technology, more and more people use projectors for briefing, video or viewing programs. In order to make the projector more portable and usable, the manufacturer has developed a small and lightweight projector to meet the miniaturized products that people expect, which will greatly reduce the size of the lens.

However, at present, the lens used in the projector is a zoom projection lens, and in order to achieve high optical performance, a curved lens or even a plurality of lenses are usually used as compensation for the optical image, and the zoom lens group is used for line projection imaging. However, in order to take into account the image quality, it is no more than the use of multiple groups of mirrors, even more than the total number of lenses is more than ten, or the use of more difficult to shape.

Therefore, the design of the conventional zoom projection lens is still not perfect, and there is still room for improvement.

In view of this, the purpose of the present invention is to provide a zoom projection lens, which is composed of three groups of mirrors and has high optical performance.

In order to achieve the above object, the present invention provides a zoom projection lens comprising a sequence from an image side to an image source side and arranged along an optical axis. Configuring a first mirror group, a second mirror group, and a third mirror group; wherein: the first mirror group has a negative refractive power, and is movable along the optical axis between the imaging side and the second mirror group The second mirror group has a positive refractive power; the third mirror group has a positive refractive power and is movable along the optical axis between the second mirror group and the image source side; further, the third mirror group includes three sheets The lens, and the refractive power of the three lenses is positive, negative, and positive from the imaging side to the image source side.

According to the above concept, the first mirror group includes a first lens which is a plano-concave lens or a convex-concave lens having a negative refractive power, and a concave surface thereof faces the image source side.

According to the above concept, the absolute value of the radius of curvature of the mirror surface of the first lens toward the imaging side is greater than the absolute value of the radius of curvature of the mirror surface toward the image source side.

According to the above concept, the second lens group includes a second lens, and the second lens is a lenticular lens having positive refractive power.

According to the above concept, the three lenses of the third lens group are respectively a third lens, a fourth lens and a fifth lens from the imaging side to the image source side; wherein the third lens has a convex surface facing the The imaging side; the fourth lens is a double concave lens; the fifth lens is a convex-concave lens, and the concave surface faces the imaging side, and the convex surface faces the image source.

According to the above concept, both mirror surfaces of the fifth lens are aspherical surfaces.

According to the above concept, an aperture is further included between the third lens and the fourth lens, and is movable along the optical axis between the second mirror group and the image source side along the optical axis.

According to the above concept, the third lens is a lenticular lens.

According to the above concept, the third lens is a convex-concave lens.

According to the above concept, the zoom projection lens further satisfies the following condition: -2.4≦Ff/F≦-1.75; wherein Ff is the focal length of the first mirror group; F is the focal length of the zoom projection lens.

According to the above concept, the zoom projection lens further satisfies the following condition: 2.07≦Fc/F≦4.7; wherein Fc is the focal length of the second mirror group; F is the focal length of the zoom projection lens.

According to the above concept, the zoom projection lens further satisfies the following condition: 1.81≦Fr/F≦3.93; wherein Fr is the focal length of the third mirror group; F is the focal length of the zoom projection lens.

According to the above concept, the zoom projection lens further satisfies the following condition: 1.13 ≦ Df / F ≦ 3.93; wherein Df is the distance between the first mirror group and the second mirror group; F is the focal length of the zoom projection lens.

According to the above concept, the zoom projection lens further satisfies the following condition: 0.29 ≦ Dr / F ≦ 2.74; wherein Dr is the distance between the second mirror group and the third mirror group; F is the focal length of the zoom projection lens.

According to the above concept, an aperture is further disposed between two of the lenses of the third mirror group, and the third mirror group is movable along the optical axis between the second mirror group and the image source side. Wherein, the aperture is located between the first lens and the second lens calculated from the imaging side to the image source side in the third mirror group.

Thereby, through the design of the above lens structure, the purpose of high optical performance can be effectively achieved.

1~3‧‧‧ zoom projection lens

G1‧‧‧ first mirror group

L1‧‧‧ first lens

G2‧‧‧Second mirror group

L2‧‧‧ second lens

G3‧‧‧ third mirror group

L3‧‧‧ third lens

L4‧‧‧ fourth lens

L5‧‧‧ fifth lens

CF‧‧‧Filter

ST‧‧‧ aperture

S1~S13‧‧‧

Z‧‧‧ optical axis

1 is a structural diagram of a zoom projection lens according to a first embodiment of the present invention; FIG. 2A is an MTF diagram of a first preferred embodiment at a wide angle end; FIG. 2B is an MTF diagram of a first preferred embodiment at a telephoto end; 2C is a distortion diagram of the first preferred embodiment at the wide angle end; FIG. 2D is a field curvature diagram of the first preferred embodiment at the wide angle end; 2E is a distortion diagram of the first preferred embodiment at the telephoto end; FIG. 2F is a field curvature diagram of the first preferred embodiment at the telephoto end; FIG. 2G is a magnification of the first preferred embodiment at the wide angle end. FIG. 2H is a schematic diagram of a magnification chromatic aberration diagram of the first preferred embodiment at the telephoto end; FIG. 3 is a structural diagram of the zoom projection lens of the second embodiment; FIG. The MTF diagram of the embodiment at the wide-angle end; FIG. 4B is an MTF diagram of the second preferred embodiment at the telephoto end; FIG. 4C is a distortion diagram of the second preferred embodiment at the wide-angle end; FIG. FIG. 4E is a distortion diagram of the second preferred embodiment at the telephoto end; FIG. 4F is a field curvature diagram of the second preferred embodiment at the telephoto end; FIG. 4G is a creation 2 is a magnification chromatic aberration diagram at the wide-angle end; FIG. 4H is a magnification chromatic aberration diagram at the telephoto end of the second preferred embodiment; FIG. 5 is a structural diagram of the zoom projection lens of the third embodiment of the present invention. FIG. 6A is an MTF diagram of the third preferred embodiment at the wide angle end; 6B is a MTF diagram of the third preferred embodiment at the telephoto end; FIG. 6C is a distortion diagram of the third preferred embodiment at the wide angle end; FIG. 6D is a field curvature of the third preferred embodiment at the wide angle end. Figure 6E is a distortion diagram of the third preferred embodiment at the telephoto end; Figure 6F is a field curvature diagram of the third preferred embodiment at the telephoto end; Figure 6G is a third preferred embodiment of the present invention in the wide angle End magnification chromatic aberration diagram; 6H is a magnification chromatic aberration diagram at the telephoto end of the third preferred embodiment of the present invention.

In order to explain the present invention more clearly, the first to third preferred embodiments will be described below in conjunction with FIGS. 1, 3 and 5, and will be described in detail later. 1 is a zoom projection lens 1 of the first embodiment of the present invention, FIG. 3 is a zoom projection lens 2 of the second embodiment of the present invention, and FIG. 5 discloses a third embodiment of the present creation. Zoom projection lens 3. The zoom lens projections 1 to 3 respectively include a first mirror group G1 and a second mirror group G2 arranged along an optical axis Z and sequentially from an imaging side to an image source side, and A third mirror group G3. In addition, according to the requirement of use, an aperture ST is disposed in the third mirror group G3, and an optical filter CF is disposed between the third mirror group G3 and the image source side to filter out The necessary noise light can achieve the purpose of improving optical performance.

The first mirror group G1 has a negative refractive power and is movable along the optical axis Z between the imaging side and the second mirror group G2. In each of the embodiments, the first lens group G1 includes only a first lens L1, and the first lens L1 has a concave surface S2 facing the image source side, and a radius of curvature of the first lens toward the mirror side of the imaging side. The absolute value is greater than the absolute value of the radius of curvature of the mirror surface toward the image source side, and the first mirror group G1 of each embodiment is different in that the first lens L1 of the first embodiment and the third embodiment is a plano-concave lens. The first lens L1 of the second embodiment is a convex-concave lens.

The second mirror group G2 has a positive refractive power and is fixed without moving. In each of the embodiments, the second lens group G2 includes only a second lens L2, and the second lens L2 is a lenticular lens having positive refractive power.

The third mirror group G3 has a positive refractive power and can be along the optical axis The second mirror group G2 moves between the image source side. The third lens group G3 includes a third lens L3, a fourth lens L4 and a fifth lens L5 arranged in sequence from the imaging side to the image source side, and the optical axis Z passes through the refractive power in sequence. Positive, negative, and positive. In each embodiment, the third lens L3 has a convex surface S5 facing the imaging side, the fourth lens L4 is a biconcave lens having a negative refractive power, and the fifth lens L5 is a convex-concave lens having a positive refractive power, and the concave surface S10 Towards the imaging side, the convex surface S11 is directed toward the image source. In addition, both mirror surfaces of the fifth lens L5 are aspherical surfaces. The third mirror group G3 of each embodiment is different in that the third lens L3 of the first embodiment and the third embodiment is a lenticular lens, and the third lens L3 of the second embodiment is a convex-concave lens.

In addition, in each embodiment, the aperture ST is located between the third lens L3 and the fourth lens L4 of the third mirror group G3, and the aperture ST can follow the third mirror group G3 in the second The mirror group G2 moves between the image source side.

In this way, through the above optical design, in actual operation, when the effective focal length of the zoom projection lenses 1 to 3 becomes long, the first mirror group G1 will greatly approach the second mirror group G2 to achieve a compensation image. Poor effect. On the other hand, when the effective focal length of the zoom projection lenses 1 to 3 becomes short, the first mirror group G1 is largely separated from the second mirror group G2 to achieve the same effect. In addition, when the object distance of the zoom projection lenses 1 to 3 becomes long, the first mirror group G1 slightly approaches the second mirror group G2 to achieve the effect of compensating for aberrations. On the other hand, when the object distance of the zoom projection lenses 1 to 3 is shortened, the first mirror group G1 is slightly smaller than the second mirror group G2 to compensate for the aberration.

In addition, when the third mirror group G3 moves relative to the second mirror group G2, the effective focal length of the zoom projection lenses 1 to 3 can be changed, wherein when the third mirror group G3 approaches the second mirror group G2 , the effective focal length of the zoom projection lens 1~3 is increased. Conversely, when the third mirror group G3 is far from the first When the two mirror group G2 is used, the effective focal length of the zoom projection lenses 1 to 3 is reduced.

In order to effectively improve the optical performance of the zoom projection lens, the optical axis Z of each lens surface of the zoom projection lenses 1 to 3 of the first to third embodiments of the present invention passes through a radius of curvature R, and each surface and the next surface are exposed to light. The distance D on the axis Z, the refractive index Nd of each lens, and the Abbe's coefficient Vd of each lens are as shown in Tables 1 to 3:

Table 3

The distance Df between the first mirror group G1 and the second mirror group G2 of the zoom projection lenses 1 to 3 of the first to third embodiments, and the distance between the second mirror group G2 and the third mirror group G3 The distance between Dr at the telephoto end and the wide-angle end is shown in Tables 4 to 6:

In addition, in each lens of the zoom projection lens of each embodiment, the surface depression z of the aspherical surfaces S10 and S11 is obtained by the following formula:

Where: z: the degree of depression of the aspheric surface; c: the reciprocal of the radius of curvature; h: the off-axis half-height of the surface; k: the conic coefficient; A~D: the coefficient of each step of the off-axis half-height of the surface.

The aspherical coefficients k and the respective order coefficients A to D of the respective aspherical surfaces S10 and S11 of the zoom projection lens of the first to third embodiments are as shown in Tables 7 to 9:

In addition, the movement through the first mirror group G1 and the third mirror group G3 has the effect of compensating for aberrations generated by different focal lengths and different object distances. In addition, with the following conditional design, the image can achieve better imaging quality: (1)-2.4≦Ff/F≦-1.75; (2)2.07≦Fc/F≦4.7; (3)1.81≦Fr /F≦3.93; (4) 1.13≦Df/F≦3.93; (5)0.29≦Dr/F≦2.74.

Wherein F is the focal length of the zoom projection lens 1~3; Ff is the focal length of the first mirror group G1; Fc is the focal length of the second mirror group G2; Fr is the focal length of the third mirror group G3.

The detailed data of the above-mentioned conditions of the zoom projection lenses 1 to 3 of the first to third embodiments of the present invention are as shown in Table 10:

As shown in FIG. 2A to FIG. 2H , the zoom projection lens 1 of the first embodiment of the present invention can achieve the imaging quality by the design of the lenses L1 L L5 and the aperture ST described above, wherein As can be seen from Fig. 2A, the zoom projection lens 1 is at the wide-angle end, and its modulation optical transfer function value is maintained at 45% or more at 47 lp/mm. As can be seen from FIG. 2B, the zoom projection lens 1 is at the telephoto end, and at 47 lp/mm, Its modulation optical transfer function value is still maintained above 40%. As can be seen from FIG. 2C and FIG. 2D, the distortion projection lens 1 has a distortion of no more than 1.8% at the wide-angle end, and the maximum field curvature does not exceed 0.12 mm and 0 mm. As can be seen from FIG. 2E and FIG. 2F, the distortion of the zoom projection lens 1 at the telephoto end does not exceed 0.35%, and the maximum field curvature does not exceed 0.04 mm and -0.1 mm. As can be seen from FIG. 2G, the lateral chromatic aberration of the zoom projection lens 1 at the wide-angle end is not more than 6 μm and -3 μm at the maximum. As can be seen from FIG. 2H, the lateral chromatic aberration of the zoom projection lens 1 at the telephoto end does not exceed 2.5 μm and -2.5 μm at the maximum. Therefore, the high optical performance of the zoom projection lens 1 can be seen from FIGS. 2A to 2H.

In addition, referring to FIG. 4A to FIG. 4H, the zoom projection lens 2 of the second embodiment of the present invention can achieve the imaging quality by the design of the lenses L1 L L5 and the aperture ST described above, wherein FIG. 4A It can be seen that the zoom projection lens 2 is at the wide-angle end, and its modulation optical transfer function value is maintained at 30% or more at 46 lp/mm. As can be seen from FIG. 4B, the zoom projection lens 2 is at the telephoto end, and its modulation optical transfer function value is maintained above 35% at 46 lp/mm. As can be seen from FIG. 4C and FIG. 4D, the distortion projection lens 2 has a distortion of no more than 1.6% at the wide-angle end, and the maximum field curvature does not exceed 0.14 mm and 0 mm. As can be seen from FIG. 4E and FIG. 4F, the distortion of the zoom projection lens 2 at the telephoto end does not exceed 0.3%, and the maximum field curvature does not exceed 0.05 mm and -0.08 mm. As can be seen from FIG. 4G, the lateral chromatic aberration of the zoom projection lens 2 at the wide-angle end does not exceed 7.5 μm and -4 μm at the maximum. As can be seen from FIG. 4H, the lateral chromatic aberration of the zoom projection lens 1 at the telephoto end is not more than 3 μm and -3 μm at the maximum. Therefore, the high optical performance of the zoom projection lens 2 can be seen from FIGS. 4A to 4H.

Furthermore, referring to FIG. 6A to FIG. 6H, the zoom projection lens 3 of the third embodiment of the present invention can achieve the imaging quality by the design of the lenses L1 L L5 and the aperture ST described above. 6A can be seen that the zoom projection lens 3 is at the wide-angle end, and at 47 lp/mm, its tone The optical transfer function value is still maintained above 45%. As can be seen from FIG. 6B, the zoom projection lens 3 is at the telephoto end, and its modulation optical transfer function value is maintained at 35% or more at 47 lp/mm. As can be seen from FIG. 6C and FIG. 6D, the distortion of the zoom projection lens 3 at the wide-angle end does not exceed -1.6%, and the maximum field curvature does not exceed 0.1 mm and -0.02 mm. As can be seen from FIG. 6E and FIG. 6F, the distortion of the zoom projection lens 3 at the telephoto end does not exceed 0.3%, and the maximum field curvature does not exceed 0.04 mm and 0.12 mm. As can be seen from FIG. 6G, the lateral chromatic aberration of the zoom projection lens 3 at the wide-angle end does not exceed 7 μm and -4 μm at the maximum. As can be seen from FIG. 6H, the lateral chromatic aberration of the zoom projection lens 1 at the telephoto end does not exceed 2.5 μm and -3 μm at the maximum. Therefore, the high optical performance of the zoom projection lens 3 can be seen from FIGS. 6A to 6H.

In summary, the zoom projection lens of the present invention can effectively achieve the purpose of zooming through the above-mentioned lens structure and optical condition design. In addition, the above design can effectively achieve the goal of high optical performance.

The above description is only for the preferred embodiment of the present invention, and equivalent changes to the application of the present patent specification and the scope of the patent application are intended to be included in the scope of the present patent.

1‧‧‧ zoom projection lens

G1‧‧‧ first mirror group

L1‧‧‧ first lens

G2‧‧‧Second mirror group

L2‧‧‧ second lens

G3‧‧‧ third mirror group

L3‧‧‧ third lens

L4‧‧‧ fourth lens

L5‧‧‧ fifth lens

SF‧‧‧Filter

ST‧‧‧ aperture

S1~S13‧‧‧

Z‧‧‧ optical axis

Claims (16)

A zoom projection lens includes a first mirror group, a second mirror group and a third mirror group arranged in an order from an imaging side to an image source side along an optical axis; wherein: the first mirror The group has a negative refractive power and is movable along the optical axis between the imaging side and the second mirror group; the second mirror group has a positive refractive power; the third mirror group has a positive refractive power and can be along the optical axis The second mirror group and the image source side move; further, the third mirror group includes three lenses, and the refractive power of the three lenses is positive, negative, and positive from the imaging side to the image source side. The zoom projection lens of claim 1, wherein the first mirror group comprises a first lens which is a plano-concave lens or a convex-concave lens having a negative refractive power, and a concave surface thereof faces the image source side. The zoom projection lens of claim 2, wherein an absolute value of a radius of curvature of the mirror surface of the first lens toward the imaging side is greater than an absolute value of a radius of curvature of the mirror surface toward the image source side. The zoom projection lens of claim 1, wherein the second lens group comprises a second lens, and the second lens is a lenticular lens having positive refractive power. The zoom projection lens of claim 1, wherein the three lenses of the third lens group are a third lens, a fourth lens and a fifth lens from the imaging side to the image source side; wherein The third lens has a convex surface facing the imaging side; the fourth lens is a double concave lens; The fifth lens is a convex-concave lens with a concave surface facing the imaging side and a convex surface facing the image source. The zoom projection lens of claim 5, wherein the two mirror surfaces of the fifth lens are aspherical surfaces. The zoom projection lens of claim 5, further comprising an aperture between the third lens and the fourth lens, and the third mirror group along the optical axis of the second mirror group and the third lens group Move between the source side. The zoom projection lens of claim 5, wherein the third lens is a lenticular lens. The zoom projection lens of claim 5, wherein the third lens is a convex-concave lens. The zoom projection lens of claim 1 further satisfies the following condition: -2.4 ≦ Ff / F ≦ - 1.75; wherein Ff is the focal length of the first mirror group; F is the focal length of the zoom projection lens. The zoom projection lens of claim 1 further satisfies the following condition: 2.07≦Fc/F≦4.7; wherein Fc is the focal length of the second mirror group; F is the focal length of the zoom projection lens. The zoom projection lens of claim 1 further satisfies the following condition: 1.81≦Fr/F≦3.93; wherein Fr is the focal length of the third mirror group; F is the focal length of the zoom projection lens. The zoom projection lens of claim 1 further satisfies the following condition: 1.13 ≦ Df / F ≦ 3.93; wherein Df is the distance between the first mirror group and the second mirror group; F is the focal length of the zoom projection lens . The zoom projection lens according to claim 1 further satisfies the following conditions: 0.29≦Dr/F≦2.74; wherein Dr is the distance between the second mirror group and the third mirror group; F is the focal length of the zoom projection lens. The zoom projection lens of claim 1, further comprising an aperture between the two lenses of the third mirror group, and the third mirror group along the optical axis of the second mirror group and the Move between the source side. The zoom projection lens of claim 15, wherein the aperture is located between the first lens and the second lens in the direction of the image side from the image side to the image source side of the third lens group.