TWI480620B - Zoom projection lens - Google Patents

Description

Zoom projection lens

The present invention relates to a projection lens, and more particularly to a zoom projection lens.

In recent years, with the advancement of imaging technology, more and more people use projectors for briefing, video, conferences or watching movies. In order to make the projector suitable for various setting environments (such as living room, conference room or classroom), the lens of the projector mostly has the function of changing the focal length, so that the projected image can be changed according to different setting environments. In addition, in order to make the projector more portable and usable, the size of the lens will be greatly reduced to meet the demand for miniaturization and weight reduction. In addition to miniaturization and weight reduction, it is also necessary to be able to It has higher optical performance to achieve high resolution and high contrast image display. Therefore, miniaturization and high optical performance are two essential requirements for a zoom projection lens.

However, at present, the zoom projection lens used in the projector is capable of achieving high optical performance, and no more than three groups of mirrors are used, and true miniaturization and weight reduction cannot be achieved. Or, in order to achieve the purpose of miniaturizing the lens, only a few lenses are used, but the light school can not be effectively improved.

In view of this, the main object of the present invention is to provide a zoom projection lens which is composed of two groups of mirrors, which is not only small in size but also has high optical performance.

In order to achieve the above objective, the zoom projection lens provided by the present invention is arranged along an optical axis and sequentially arranged from an imaging side to an image source side, and a first mirror group and a second mirror group; wherein, the first The mirror group has a negative refractive power; the refractive power of the first three lenses in the first mirror group from the imaging side to the image source side is negative, positive and negative in sequence; the second mirror group has a positive refractive power; the second The last lens in the mirror group from the imaging side to the image source side has a positive refractive power, and at least one side is an aspherical surface; in addition, the first mirror group may be between the imaging side and the second mirror group. The optical axis moves.

Thereby, the first mirror group is moved to achieve the purpose of changing the focal length of the lens.

In order that the present invention may be more clearly described, the preferred embodiments are illustrated in the accompanying drawings.

1 is a lens configuration diagram of a zoom projection lens 1 according to a first preferred embodiment of the present invention, which includes a film along the optical axis Z and arranged in an order from the imaging side to the image source side and made of glass. A mirror group G1 and a second mirror group G2. In addition, the first mirror group G1 can be moved along the optical axis Z between the imaging side and the second mirror group G2 to achieve the purpose of changing the focal length of the lens, so that the zoom projection lens 1 can be according to the first mirror group G1. The position is divided into a wide-angle state, a middle state, and a telephoto state. Furthermore, depending on the requirements of use, a glass cover CG (Cover Glass) may be disposed between the second mirror group G2 and the image source side, which is a flat glass. among them:

The first mirror group G1 has a negative refractive power and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The first lens L1 is a crescent lens having a negative refractive power, and its convex surface R1 faces the imaging side. The second lens L2 is a lenticular lens having a positive refractive power. The third lens L3 is a crescent lens having a negative refractive power, and its convex surface R5 faces the imaging side. The fourth lens L4 is a biconcave lens having a negative refractive power. The fifth lens L5 is a single convex lens having a positive refractive power, and its convex surface R9 faces the imaging side.

The second mirror group G2 has a positive refractive power and includes a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10 and an eleventh lens L11. The sixth lens L6 is a single convex lens having a positive refractive power, and its convex surface R11 faces the image forming side. The seventh lens L7 is a biconcave lens having a negative refractive power. The eighth lens L8 is a lenticular lens having a positive refractive power, and the aperture ST of the zoom projection lens 1 is disposed on the surface R16 of the eighth lens L8. The ninth lens L9 is a crescent lens having a positive refractive power, and its convex surface R17 faces the image forming side. The tenth lens L10 is a biconcave lens having a negative refractive power. The eleventh lens L11 is a lenticular lens having a positive refractive power, and the surfaces R21 and R22 thereof are all aspherical surfaces.

In order to enable the zoom projection lens 1 to effectively reduce the total length of the lens and correct the aberration, the zoom projection lens 1 satisfies the following conditions:

(1) -0.87<f2/f1<-0.76 (2) -2.09<f1/fw<-1.85

(3) 1.59<f2/fw<1.64 (4) 0.70<fw/bf<0.71

(5) 6.66<tt/fw<6.7 (6) 4.7<tt/bf<4.74

Where f1 is the effective focal length of the first mirror group G1; f2 is the effective focal length of the second mirror group G2; fw is the effective focal length of the zoom projection lens 1 in the wide-angle state; bf is the zoom The focal length of the projection lens 1; tt is the total length of the zoom projection lens 1.

In addition, in order to enable the zoom projection lens 1 to effectively reduce the total length of the lens and increase the back focus length, the zoom projection lens 1 satisfies the following conditions:

(7) -1.31<ex/bf<-1.24 (8) 0.787<lt/tt<0.789

(9) 1.31<fg/fw<2.2

Where ex is the exit pupil position of the zoom projection lens 1; lt is the length between the first surface R1 and the last surface R24 of the zoom projection lens 1; fg is the eleventh lens L11 Effective focal length.

The focal length F (Focus Length) of the zoom projection lens 1 of the first embodiment of the present invention, the numerical aperture FNO (F-number), the radius of curvature R of the optical axis Z of each lens surface, and the respective lenses are The thickness T on the optical axis Z, the refractive index Nd (refractive index) of each lens, and the Abbe number of each lens are shown in Table 1:

In the thickness T of Table 1, (W) refers to the distance between the zoom projection lens 1 on the optical axis Z in the wide-angle state; (M) means that the zoom projection lens 1 is in the middle (middle) In the state, the distance between the optical axes Z; (T) refers to the distance between the zoom projection lens 1 on the optical axis Z in the telephoto state.

In addition, the surface depression degree D of the aspherical surfaces R21 and R22 of the eleventh lens L11 of the present embodiment is obtained by the following formula:

Where: D: the degree of depression of the aspheric surface; C: the reciprocal of the radius of curvature; H: the aperture radius of the surface; K: the conic coefficient; E ₄ ~ E ₁₄ : the order factor of the aperture radius H of the surface.

In this embodiment, the conic coefficients of the respective aspherical surfaces and the order coefficients E ₄ to E _{14 of the} surface aperture radius H are as shown in Table 2:

With the above arrangement of the lens and the aperture, the zoom projection lens 1 of the present embodiment can effectively reduce the volume to meet the demand for light weight, and the zoom projection lens 1 has an image quality in a wide-angle state. The requirements can also be met, as can be seen from Figures 2A to 2D.

2A is a longitudinal chromatic aberration diagram of the zoom projection lens 1 of the present embodiment; FIG. 2B is a lateral chromatic aberration diagram of the zoom projection lens 1 of the present embodiment; and FIG. 2C is the embodiment. The field curvature map and the distortion map of the zoom projection lens 1 are shown in FIG. 2D, which is a spatial frequency modulation transfer function map (Spatial Frequency MTF) of the zoom projection lens 1 of the present embodiment. As can be seen from FIG. 2A and FIG. 2B, the longitudinal chromatic aberration of the zoom projection lens 1 of the present embodiment does not exceed 0.07 mm and -0.03 mm at the maximum, and the lateral chromatic aberration does not exceed 4 μm and -1 μm at the maximum. As can be seen from FIG. 2C, the maximum field curvature of the zoom projection lens 1 of the present embodiment does not exceed 0.10 mm and -0.04 mm, and the distortion variable does not exceed 2%. As can be seen from FIG. 2D, when the zoom projection lens 1 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 50% or more.

In addition, when the zoom projection lens 1 is in the middle state, its image quality can also be achieved, which can be seen from FIG. 3A to FIG. 3D. As can be seen from FIG. 3A and FIG. 3B, the longitudinal chromatic aberration of the zoom projection lens 1 of the present embodiment does not exceed 0.07 mm and -0.05 mm at the maximum, and the lateral chromatic aberration does not exceed 4 μm and -2 μm at the maximum. As can be seen from FIG. 3C, the maximum field curvature of the zoom projection lens 1 of the present embodiment does not exceed 0.10 mm and -0.08 mm, and the distortion variable does not exceed 0.8%. As can be seen from FIG. 3D, when the zoom projection lens 1 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more.

Furthermore, the zoom projection lens 1 can also meet the imaging quality in the telephoto state, which can be seen from FIG. 4A to FIG. 4D. As can be seen from FIGS. 4A and 4B, the longitudinal chromatic aberration of the zoom projection lens 1 of the present embodiment does not exceed 0.08 mm and -0.08 mm at the maximum, and the lateral chromatic aberration does not exceed 4 μm and -4 μm at the maximum. As can be seen from FIG. 4C, the maximum field curvature of the zoom projection lens 1 of the present embodiment does not exceed 0.12 mm and -0.12 mm, and the distortion variable does not exceed 0.4%. As can be seen from FIG. 4D, when the zoom projection lens 1 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more. It is apparent that the resolution of the zoom projection lens 1 of the present embodiment is It is a standard when it is a wide-angle state, a middle state, or a telephoto state.

The above is the zoom projection lens 1 of the first embodiment of the present invention; in accordance with the technology of the present invention, a second embodiment of the present invention will be described below with reference to FIG.

The zoom projection lens 2 of the present embodiment includes a first mirror group G1 and a second mirror group G2 which are arranged along the optical axis Z and are arranged in order from the imaging side to the image source side and are made of glass. In addition, the first mirror group G1 can also move along the optical axis Z between the imaging side and the second mirror group G2 to change the focal length of the lens, so that the zoom projection lens can be positioned according to the first mirror group G1. It is divided into a wide-angle state, a middle state, and a telephoto state. Furthermore, a glass cover CG (Cover Glass) is disposed between the second mirror group G2 and the image source side.

The first mirror group G1 has a negative refractive power, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The first lens L1 is a crescent lens having a negative refractive power, and the convex surface R1 faces the imaging side. The second lens L2 is a lenticular lens having a positive refractive power. The third lens L3 is a crescent lens having a negative refractive power, and its convex surface R5 faces the imaging side. The fourth lens L4 is a biconcave lens having a negative refractive power. The fifth lens L5 is a single convex lens having a positive refractive power, and its convex surface R9 faces the imaging side.

The second mirror group G2 has a positive refractive power, and includes a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, and a Twelfth lens L12. The sixth lens L6 is a lenticular lens having a positive refractive power. The seventh lens L7 is a crescent lens having a positive refractive power, and its convex surface R13 faces the image forming side. The eighth lens L8 is a single concave lens having a negative refractive power, and its concave surface R15 faces the image forming side. The ninth lens L9 is a crescent lens having a negative refractive power, and its concave surface R17 faces the image forming side. The tenth lens L10 is a lenticular lens having a positive refractive power, and the aperture ST of the zoom projection lens 2 is disposed on the surface R19 of the tenth lens L10. The eleventh lens L11 is a negative refractive power biconcave lens. The twelfth lens L12 is a lenticular lens having positive refractive power, and the surfaces R23 and R24 thereof are all aspherical surfaces.

In order to enable the zoom projection lens 2 to effectively reduce the total length of the lens, correct the aberration, and increase the back focus length, the zoom projection lens 2 satisfies the following conditions:

(1) -0.87<f2/f1<-0.76 (2) -2.09<f1/fw<-1.85

(3) 1.59<f2/fw<1.64 (4) 0.70<fw/bf<0.71

(5) 6.66<tt/fw<6.7 (6) 4.7<tt/bf<4.74

(7) -1.31<ex/bf<-1.24 (8) 0.787<lt/tt<0.789

(9) 1.31<fg/fw<2.2

Where f1 is the effective focal length of the first mirror group G1; f2 is the effective focal length of the second mirror group G2; fw is the effective focal length of the zoom projection lens 2 in the wide-angle state; bf is the zoom The focal length of the projection lens 2; tt is the total length of the zoom projection lens 2; ex is the exit pupil position of the zoom projection lens 2; lt is the first surface R1 to the last of the zoom projection lens 2 The length between one surface R26; fg is the effective focal length of the twelfth lens L12.

The focal length F (Focus Length) of the zoom projection lens 2 of the second embodiment of the present invention, the numerical aperture FNO (F-number), the radius of curvature R of the optical axis Z of each lens surface, and the respective lenses are The thickness T on the optical axis Z, the refractive index Nd (refractive index) of each lens, and the Abbe number of each lens are shown in Table 3:

In the thickness T of Table 3, (W) refers to the distance between the zoom projection lens 2 on the optical axis Z in the wide-angle state; (M) means that the zoom projection lens 2 is in the middle (middle) In the state, the distance between the optical axes Z; (T) refers to the distance between the zoom projection lens 2 on the optical axis Z in the telephoto state.

In addition, the surface depression degree D of the aspherical surfaces R23 and R24 of the twelfth lens L12 of the present embodiment is obtained by the following formula:

Where: D: the degree of depression of the aspheric surface; C: the reciprocal of the radius of curvature; H: the aperture radius of the surface; K: the conic coefficient; E ₄ ~ E ₁₄ : the order factor of the aperture radius H of the surface.

In the present embodiment, the conic coefficients of the respective aspherical surfaces and the order coefficients E ₄ to E _{14 of the} surface aperture radius H are as shown in Table 4:

With the above arrangement of the lens and the aperture, the zoom projection lens 2 of the present embodiment can effectively reduce the volume to meet the demand for light weight, and the zoom projection lens 2 has an image quality in a wide-angle state. The requirements can also be met, as can be seen from Figures 6A to 6D. FIG. 6A is a longitudinal chromatic aberration diagram of the zoom projection lens 2 of the present embodiment; FIG. 6B is a lateral chromatic aberration diagram of the zoom projection lens 2 of the present embodiment; and FIG. 6C is the embodiment. The field curvature map and the distortion map of the zoom projection lens 2; FIG. 6D shows the spatial frequency modulation transfer function map (Spatial Frequency MTF) of the zoom projection lens 2 of the present embodiment. As can be seen from FIG. 6A and FIG. 6B, the longitudinal chromatic aberration of the zoom projection lens 2 of the present embodiment does not exceed 0.08 mm and -0.04 mm at the maximum, and the lateral chromatic aberration does not exceed 7 μm and -1 μm at the maximum. As can be seen from FIG. 6C, the maximum field curvature of the zoom projection lens 2 of the present embodiment does not exceed 0.16 mm and -0.04 mm, and the distortion variable does not exceed 2%. As can be seen from FIG. 6D, when the zoom projection lens 2 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more.

In addition, when the zoom projection lens 2 is in the middle state, its image quality can also be achieved, which can be seen from FIGS. 7A to 7D. As can be seen from FIGS. 7A and 7B, the longitudinal chromatic aberration of the zoom projection lens 2 of the present embodiment does not exceed 0.08 mm and -0.03 mm at the maximum, and the lateral chromatic aberration does not exceed 4 μm and -1 μm at the maximum. As can be seen from FIG. 7C, the maximum field curvature of the zoom projection lens 2 of the present embodiment does not exceed 0.12 mm and -0.04 mm, and the distortion variable does not exceed 1.6%. As can be seen from FIG. 7D, when the zoom projection lens 2 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 50% or more.

Furthermore, the zoom projection lens 2 can also meet the imaging quality in the telephoto state, which can be seen from FIG. 8A to FIG. 8D. As can be seen from FIGS. 8A and 8B, the longitudinal chromatic aberration of the zoom projection lens 2 of the present embodiment does not exceed 0.12 mm and -0.05 mm at the maximum, and the lateral chromatic aberration does not exceed 5 μm and -3 μm at the maximum. As can be seen from FIG. 8C, the maximum field curvature of the zoom projection lens 2 of the present embodiment does not exceed 0.16 mm and -0.12 mm, and the distortion variable does not exceed 0.4%. As can be seen from FIG. 8D, when the zoom projection lens 2 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more. Thereby, it is apparent that the resolution of the zoom projection lens 2 of the present embodiment conforms to the standard regardless of whether it is a wide-angle state, a middle state, or a telephoto state.

Please refer to FIG. 9 , which is a lens configuration diagram of a zoom projection lens 3 according to a third preferred embodiment of the present invention, which includes a film along the optical axis Z and arranged in an order from the imaging side to the image source side and made of glass. A mirror group G1 and a second mirror group G2. The first mirror group G1 can be moved along the optical axis Z between the imaging side and the second mirror group G2 to change the focal length of the lens, so that the zoom projection lens 3 can be divided into wide angles according to the position of the first mirror group G1. (wide-angle) state, middle state, and telephoto state. Further, a glass cover CG (Cover Glass) is provided between the second mirror group G2 and the image source side. among them:

The first mirror group G1 has a negative refractive power, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The first lens L1 is a crescent lens having a negative refractive power, and the convex surface R1 faces the imaging side. The second lens L2 is a lenticular lens having a positive refractive power. The third lens L3 is a crescent lens having a negative refractive power, and its convex surface R5 faces the imaging side. The fourth lens L4 is a biconcave lens having a negative refractive power. The fifth lens L5 is a crescent lens having a positive refractive power, and its convex surface R9 faces the image forming side.

The second mirror group G2 has a positive refractive power, and includes a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, and a Twelfth lens L12. The sixth lens L6 is a lenticular lens having a positive refractive power. The seventh lens L7 is a crescent lens having a positive refractive power, and its convex surface R13 faces the image forming side. The eighth lens L8 is a crescent lens having a negative refractive power, and its convex surface R15 faces the image forming side. The ninth lens L9 is a cemented lens having a negative refractive power, which is formed by gluing a lenticular lens L91 and a double concave lens L92, and the lenticular lens L91 is closer to the imaging side than the biconcave lens L92. The tenth lens L10 is a lenticular lens having a positive refractive power, and the aperture ST of the zoom projection lens 3 is disposed on the surface R20 of the tenth lens L10. The eleventh lens L11 is a biconcave lens having a negative refractive power. The twelfth lens L12 is a single convex lens having a positive refractive power, and the convex surface R24 faces the image forming side and is an aspherical surface.

In order to enable the zoom projection lens 3 to effectively reduce the total length of the lens, correct the aberration, and increase the back focus length, the zoom projection lens 3 satisfies the following conditions:

(1) -0.87<f2/f1<-0.76 (2) -2.09<f1/fw<-1.85

(3) 1.59<f2/fw<1.64 (4) 0.70<fw/bf<0.71

(5) 6.66<tt/fw<6.7 (6) 4.7<tt/bf<4.74

(7) -1.31<ex/bf<-1.24 (8) 0.787<lt/tt<0.789

(9) 1.31<fg/fw<2.2

Where f1 is the effective focal length of the first mirror group G1; f2 is the effective focal length of the second mirror group G2; fw is the effective focal length of the zoom projection lens 3 in the wide-angle state; bf is the zoom The focal length of the projection lens 3; tt is the total length of the zoom projection lens 3; ex is the exit pupil position of the zoom projection lens 3; lt is the first surface R1 to the last of the zoom projection lens 3. The length between one surface R27; fg is the effective focal length of the twelfth lens L12.

The focal length F (Focus Length) of the zoom projection lens 3 of the third embodiment of the present invention, the numerical aperture FNO (F-number), the radius of curvature R of the optical axis Z of each lens surface, and the respective lenses are The thickness T on the optical axis Z, the refractive index Nd (refractive index) of each lens, and the Abbe number of each lens are shown in Table 5:

In the thickness T of Table 5, (W) refers to the distance between the zoom projection lens 3 on the optical axis Z in the wide-angle state; (M) means that the zoom projection lens 3 is in the middle (middle) In the state, the distance between the optical axes Z; (T) refers to the distance between the zoom projection lens 3 on the optical axis Z in the telephoto state.

In addition, the surface depression D of the aspherical surface R24 of the twelfth lens L12 of the present embodiment is obtained by the following formula:

Where: D: the degree of depression of the aspheric surface; C: the reciprocal of the radius of curvature; H: the aperture radius of the surface; K: the conic coefficient; E ₄ ~ E ₁₄ : the order factor of the aperture radius H of the surface.

In this embodiment, the conic coefficients of the respective aspherical surfaces and the order coefficients E ₄ to E _{14 of the} surface aperture radius H are as shown in Table 6:

With the above arrangement of the lens and the aperture, the zoom projection lens 3 of the present embodiment can effectively reduce the volume to meet the demand for light weight, and the zoom projection lens 3 has an image quality in a wide-angle state. A requirement can also be met, as can be seen from Figures 10A to 10D. FIG. 10A is a longitudinal chromatic aberration diagram of the zoom projection lens 3 of the present embodiment; FIG. 10B is a lateral chromatic aberration diagram of the zoom projection lens 3 of the present embodiment; and FIG. 10C is the embodiment. The field curvature map and the distortion map of the zoom projection lens 3; FIG. 10D shows the spatial frequency modulation transfer function map (Spatial Frequency MTF) of the zoom projection lens 3 of the present embodiment. As can be seen from FIGS. 10A and 10B, the longitudinal chromatic aberration of the zoom projection lens 3 of the present embodiment does not exceed 0.09 mm and -0.04 mm at the maximum, and the lateral chromatic aberration does not exceed 6 μm and -2 μm at the maximum. As can be seen from FIG. 10C, the maximum field curvature of the zoom projection lens 3 of the present embodiment does not exceed 0.12 mm and -0.08 mm, and the distortion variable does not exceed 2%. As can be seen from FIG. 10D, when the zoom projection lens 3 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more.

In addition, when the zoom projection lens 3 is in the middle state, its image quality can also be achieved, which can be seen from FIG. 11A to FIG. 11D. As can be seen from FIGS. 11A and 11B, the longitudinal chromatic aberration of the zoom projection lens 3 of the present embodiment does not exceed 0.08 mm and -0.02 mm at the maximum, and the lateral chromatic aberration does not exceed 2 μm and -1 μm at the maximum. As can be seen from FIG. 11C, the maximum field curvature of the zoom projection lens 3 of the present embodiment does not exceed 0.10 mm and -0.08 mm, and the distortion variable does not exceed 1.2%. As can be seen from FIG. 11D, when the zoom projection lens 3 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 50% or more.

Furthermore, the zoom projection lens 3 can also meet the imaging quality in the telephoto state, which can be seen from FIG. 12A to FIG. 12D. As can be seen from FIGS. 12A and 12B, the longitudinal chromatic aberration of the zoom projection lens 3 of the present embodiment does not exceed 0.07 mm and -0.06 mm at the maximum, and the lateral chromatic aberration does not exceed 2 μm and -2 μm at the maximum. As can be seen from FIG. 12C, the maximum field curvature of the zoom projection lens 3 of the present embodiment does not exceed 0.04 mm and -0.16 mm, and the distortion variable does not exceed 0.4%. As can be seen from FIG. 12D, when the zoom projection lens 3 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more. Thereby, it is apparent that the resolution of the zoom projection lens 3 of the present embodiment conforms to the standard regardless of whether it is a wide-angle state, a middle state, or a telephoto state.

Please refer to FIG. 13 , which is a lens configuration diagram of a zoom projection lens 4 according to a fourth preferred embodiment of the present invention, which includes a glass made of glass and arranged along the optical axis Z and sequentially arranged from the imaging side to the image source side. A mirror group G1 and a second mirror group G2. The first mirror group G1 can be moved along the optical axis Z between the imaging side and the second mirror group G2 to change the focal length of the lens, so that the zoom projection lens 4 can be divided into wide angles according to the position of the first mirror group G1. (wide-angle) state, middle state, and telephoto state. Further, a glass cover CG (Cover Glass) is provided between the second mirror group G2 and the image source side. among them:

The first mirror group G1 has a negative refractive power, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. The first lens L1 is a crescent lens having a negative refractive power, and the convex surface R1 faces the imaging side. The second lens L2 is a lenticular lens having a positive refractive power. The third lens L3 is a crescent lens having a negative refractive power, and its convex surface R5 faces the imaging side. The fourth lens L4 is a biconcave lens having a negative refractive power. The fifth lens L5 is a lenticular lens having a positive refractive power. The sixth lens L6 is a crescent lens having a negative refractive power, and its concave surface R11 faces the image forming side.

The second mirror group G2 has a positive refractive power and includes a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11 and a twelfth lens L12. The seventh lens L7 is a lenticular lens having a positive refractive power. The eighth lens L8 is a biconcave lens having a negative refractive power. The ninth lens L9 is a single convex lens having a positive refractive power, and its convex surface R17 faces the image forming side. The tenth lens L10 is a crescent lens having a positive refractive power, and its convex surface R20 faces the image forming side. The eleventh lens L11 is a biconcave lens having a negative refractive power. The twelfth lens L12 is a lenticular lens having positive refractive power, and the surfaces R24 and R25 thereof are all aspherical surfaces. In addition, the aperture ST of the zoom projection lens 4 is disposed between the ninth lens L9 and the tenth lens L10.

In order to enable the zoom projection lens 4 to effectively reduce the total length of the lens, correct the aberration, and increase the back focus length, the zoom projection lens 4 satisfies the following conditions:

(1) -0.87<f2/f1<-0.76 (2) -2.09<f1/fw<-1.85

(3) 1.59<f2/fw<1.64 (4) 0.70<fw/bf<0.71

(5) 6.66<tt/fw<6.7 (6) 4.7<tt/bf<4.74

(7) -1.31<ex/bf<-1.24 (8) 0.787<lt/tt<0.789

(9) 1.31<fg/fw<2.2

Where f1 is the effective focal length of the first mirror group G1; f2 is the effective focal length of the second mirror group G2; fw is the effective focal length of the zoom projection lens 4 in the wide-angle state; bf is the zoom The focal length of the projection lens 4; tt is the total length of the zoom projection lens 4; ex is the exit pupil position of the zoom projection lens 4; lt is the first surface R1 to the last of the zoom projection lens 4. The length between one surface R27; fg is the effective focal length of the twelfth lens L12.

The focal length F (Focus Length), the numerical aperture FNO (F-number) of the zoom projection lens 4 of the fourth embodiment of the present invention, and the radius of curvature R of the optical axis Z of each lens surface, and the respective lenses are The thickness T on the optical axis Z, the refractive index Nd (refractive index) of each lens, and the Abbe number of each lens are shown in Table 7:

In the thickness T of Table 7, (W) refers to the distance between the zoom projection lens 4 on the optical axis Z in the wide-angle state; (M) means that the zoom projection lens 4 is in the middle (middle) In the state, the distance between the optical axes Z; (T) refers to the distance between the zoom projection lens 4 on the optical axis Z in the telephoto state.

In addition, the surface depression degree D of the aspherical surfaces R24 and R25 of the twelfth lens L12 of the present embodiment is obtained by the following formula:

Where: D: the degree of depression of the aspheric surface; C: the reciprocal of the radius of curvature; H: the aperture radius of the surface; K: the conic coefficient; E ₄ ~ E ₁₄ : the order factor of the aperture radius H of the surface.

In the present embodiment, the conic coefficients of the respective aspherical surfaces and the order coefficients E ₄ to E _{14 of the} surface aperture radius H are as shown in Table 8:

The zoom projection lens 4 of the present embodiment can effectively reduce the volume to meet the demand for light weight by the above-described configuration of the lens and the aperture. The zoom projection lens 4 has an image quality in a wide-angle state. A requirement can also be met, as can be seen from Figures 14A to 14D. FIG. 14A is a longitudinal chromatic aberration diagram of the zoom projection lens 4 of the present embodiment; FIG. 14B is a lateral chromatic aberration diagram of the zoom projection lens 4 of the present embodiment; and FIG. 14C is the embodiment. The field curvature map and the distortion map of the zoom projection lens 4; FIG. 14D shows the spatial frequency modulation transfer function map (Spatial Frequency MTF) of the zoom projection lens 4 of the present embodiment. As can be seen from FIGS. 14A and 14B, the longitudinal chromatic aberration of the zoom projection lens 4 of the present embodiment does not exceed 0.08 mm and -0.02 mm at the maximum, and the lateral chromatic aberration does not exceed 2 μm and -1 μm at the maximum. As can be seen from FIG. 14C, the maximum field curvature of the zoom projection lens 4 of the present embodiment does not exceed 0.10 mm and -0.08 mm, and the distortion variable does not exceed 1.2%. As can be seen from FIG. 14D, when the zoom projection lens 4 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 50% or more.

In addition, when the zoom projection lens 4 is in the middle state, its imaging quality can also be achieved, which can be seen from FIGS. 15A to 15D. As can be seen from FIGS. 15A and 15B, the longitudinal chromatic aberration of the zoom projection lens 4 of the present embodiment does not exceed 0.07 mm and -0.06 mm at the maximum, and the lateral chromatic aberration does not exceed 2 μm and -2 μm at the maximum. As can be seen from FIG. 15C, the maximum field curvature of the zoom projection lens 4 of the present embodiment does not exceed 0.04 mm and -0.16 mm, and the distortion variable does not exceed 0.4%. As can be seen from FIG. 15D, when the zoom projection lens 4 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more.

Furthermore, the zoom projection lens 4 can also meet the imaging quality in the telephoto state, which can be seen from FIG. 16A to FIG. 16D. As can be seen from FIGS. 16A and 16B, the longitudinal chromatic aberration of the zoom projection lens 4 of the present embodiment does not exceed 0.08 mm and -0.03 mm at the maximum, and the lateral chromatic aberration does not exceed 4 μm and -2 μm at the maximum. As can be seen from FIG. 16C, the maximum field curvature of the zoom projection lens 4 of the present embodiment does not exceed 0.16 mm and -0.08 mm, and the distortion variable does not exceed 2%. As can be seen from FIG. 16D, when the zoom projection lens 4 of the present embodiment is at 60 lp/mm, the modulation optical transfer function value is maintained at 40% or more. Thereby, it is apparent that the resolution of the zoom projection lens 4 of the present embodiment conforms to the standard regardless of whether it is a wide-angle state, a middle state, or a telephoto state.

In summary, it can be seen that the zoom projection lens of the present invention only needs to use two sets of mirrors to achieve the purpose of zooming, and is not only small in size but also high in optical performance.

The above description is only for the preferred embodiments of the present invention, and the equivalent structures and manufacturing methods of the present invention and the scope of the patent application are intended to be included in the scope of the present invention.

1. . . Zoom projection lens

G1. . . First mirror group

L1. . . First lens

L2. . . Second lens

L3. . . Third lens

L4. . . Fourth lens

L5. . . Fifth lens

G2. . . Second mirror group

L6. . . Sixth lens

L7. . . Seventh lens

L8. . . Eighth lens

L9. . . Ninth lens

L10. . . Tenth lens

L11. . . Eleventh lens

CG. . . Glass cover

ST. . . aperture

R1~R24. . . surface

Z. . . Optical axis

2. . . Zoom projection lens

G1. . . First mirror group

L1. . . First lens

L2. . . Second lens

L3. . . Third lens

L4. . . Fourth lens

L5. . . Fifth lens

Second mirror group

L6. . . Sixth lens

L7. . . Seventh lens

L8. . . Eighth lens

L9. . . Ninth lens

L10. . . Tenth lens

L11. . . Eleventh lens

L12. . . Twelfth lens

CG. . . Glass cover

ST. . . aperture

R1~R26. . . surface

Z. . . Optical axis

3. . . Zoom projection lens

G1. . . First mirror group

L1. . . First lens

L2. . . Second lens

L3. . . Third lens

L4. . . Fourth lens

L5. . . Fifth lens

Second mirror group

L6. . . Sixth lens

L7. . . Seventh lens

L8. . . Eighth lens

L9. . . Ninth lens

L91. . . Lenticular lens

L92. . . Double concave lens

L10. . . Tenth lens

L11. . . Eleventh lens

L12. . . Twelfth lens

CG. . . Glass cover

ST. . . aperture

R1~R27. . . surface

Z. . . Optical axis

4. . . Zoom projection lens

G1. . . First mirror group

L1. . . First lens

L2. . . Second lens

L3. . . Third lens

L4. . . Fourth lens

L5. . . Fifth lens

L6. . . Sixth lens

Second mirror group

L7. . . Seventh lens

L8. . . Eighth lens

L9. . . Ninth lens

L10. . . Tenth lens

L11. . . Eleventh lens

L12. . . Twelfth lens

CG. . . Glass cover

ST. . . aperture

R1~R27. . . surface

Z. . . Optical axis

1 is a lens configuration diagram of a first preferred embodiment of the present invention.

Fig. 2A is a longitudinal chromatic aberration diagram of the first preferred embodiment in a wide-angle state.

Fig. 2B is a lateral chromatic aberration diagram of the first preferred embodiment in a wide-angle state.

2C is a field curvature diagram and a distortion diagram of the first preferred embodiment in a wide-angle state.

2D is an MTF diagram of the first preferred embodiment in a wide-angle state.

Fig. 3A is a longitudinal chromatic aberration diagram of the first preferred embodiment in an intermediate state.

Fig. 3B is a lateral chromatic aberration diagram of the first preferred embodiment in an intermediate state.

Fig. 3C is a field curvature diagram and a distortion diagram of the first preferred embodiment in an intermediate state.

Figure 3D is an MTF diagram of the first preferred embodiment in an intermediate state.

4A is a longitudinal chromatic aberration diagram of the first preferred embodiment in a telephoto state.

Figure 4B is a lateral chromatic aberration diagram of the first preferred embodiment in the telephoto state.

4C is a field curvature diagram and a distortion diagram of the first preferred embodiment in a remote projection state.

4D is an MTF diagram of the first preferred embodiment in a telephoto state.

Figure 5 is a perspective view of a lens configuration in accordance with a second preferred embodiment of the present invention.

Fig. 6A is a longitudinal chromatic aberration diagram of the second preferred embodiment in a wide-angle state.

Fig. 6B is a lateral chromatic aberration diagram of the second preferred embodiment in the wide-angle state.

Fig. 6C is a field curvature diagram and a distortion diagram of the second preferred embodiment in a wide-angle state.

Fig. 6D is an MTF diagram of the second preferred embodiment in a wide-angle state.

Fig. 7A is a longitudinal chromatic aberration diagram of the second preferred embodiment in an intermediate state.

Fig. 7B is a lateral chromatic aberration diagram of the second preferred embodiment in an intermediate state.

Fig. 7C is a field curvature diagram and a distortion diagram of the second preferred embodiment in an intermediate state.

Figure 7D is an MTF diagram of the second preferred embodiment in an intermediate state.

Figure 8A is a longitudinal chromatic aberration diagram of the second preferred embodiment in the telephoto state.

Figure 8B is a lateral chromatic aberration diagram of the second preferred embodiment in the telephoto state.

FIG. 8C is a field curvature diagram and a distortion diagram of the second preferred embodiment in a telephoto state.

Figure 8D is an MTF diagram of the second preferred embodiment in a telephoto state.

Figure 9 is a perspective view of a lens arrangement in accordance with a third preferred embodiment of the present invention.

Fig. 10A is a longitudinal chromatic aberration diagram of the third preferred embodiment in a wide-angle state.

Fig. 10B is a lateral chromatic aberration diagram of the third preferred embodiment in the wide-angle state.

Fig. 10C is a field curvature diagram and a distortion diagram of the third preferred embodiment in a wide-angle state.

Fig. 10D is an MTF diagram of the third preferred embodiment in a wide-angle state.

Figure 11A is a longitudinal chromatic aberration diagram of the third preferred embodiment in an intermediate state.

Figure 11B is a lateral chromatic aberration diagram of the third preferred embodiment in an intermediate state.

Figure 11C is a field curvature diagram and a distortion diagram of the third preferred embodiment in an intermediate state.

Figure 11D is an MTF diagram of the third preferred embodiment in an intermediate state.

Figure 12A is a longitudinal chromatic aberration diagram of the third preferred embodiment in a telephoto state.

Figure 12B is a lateral chromatic aberration diagram of the third preferred embodiment in the telephoto state.

Fig. 12C is a field curvature diagram and a distortion diagram of the third preferred embodiment in a telephoto state.

Figure 12D is an MTF diagram of the third preferred embodiment in a telephoto state.

Figure 13 is a perspective view of a lens configuration according to a fourth preferred embodiment of the present invention.

Fig. 14A is a longitudinal chromatic aberration diagram of the fourth preferred embodiment in a wide-angle state.

Fig. 14B is a lateral chromatic aberration diagram of the fourth preferred embodiment in the wide-angle state.

Fig. 14C is a field curvature diagram and a distortion diagram of the fourth preferred embodiment in a wide-angle state.

Fig. 14D is an MTF diagram of the fourth preferred embodiment in a wide-angle state.

Fig. 15A is a longitudinal chromatic aberration diagram of the fourth preferred embodiment in an intermediate state.

Figure 15B is a lateral chromatic aberration diagram of the fourth preferred embodiment in an intermediate state.

Fig. 15C is a field curvature diagram and a distortion diagram of the fourth preferred embodiment in an intermediate state.

Figure 15D is an MTF diagram of the fourth preferred embodiment in an intermediate state.

Figure 16A is a longitudinal chromatic aberration diagram of the fourth preferred embodiment in a telephoto state.

Figure 16B is a lateral chromatic aberration diagram of the fourth preferred embodiment in the telephoto state.

Figure 16C is a field curvature diagram and a distortion diagram of the fourth preferred embodiment in a telephoto state.

Figure 16D is an MTF diagram of the fourth preferred embodiment in a telephoto state.

1. . . Zoom projection lens

G1. . . First mirror group

L1. . . First lens

L2. . . Second lens

L3. . . Third lens

L4. . . Fourth lens

L5. . . Fifth lens

G2. . . Second mirror group

L6. . . Sixth lens

L7. . . Seventh lens

L8. . . Eighth lens

L9. . . Ninth lens

L10. . . Tenth lens

L11. . . Eleventh lens

CG. . . Glass cover

ST. . . aperture

R1~R24. . . surface

Z. . . Optical axis

Claims (12)

A zoom projection lens includes a first mirror group and a second mirror group arranged along an optical axis and arranged from an imaging side to an image source side; wherein the first mirror group has a negative refractive power; The refractive power of the first three lenses in the first mirror group from the imaging side to the image source side is negative, positive and negative in sequence; the second mirror group has a positive refractive power; and the second mirror group has the imaging side Up to the image source side, the last lens has a positive refractive power, and at least one side is an aspherical surface; in addition, the first mirror group can move along the optical axis between the imaging side and the second mirror group; The zoom projection lens further satisfies the following condition: 1.31<fg/fw<2.2, where fw is the effective focal length of the zoom projection lens in a wide-angle state; fg is the second mirror group from the imaging side to the The effective focal length of the last lens is counted from the source side. The zoom projection lens of claim 1, further comprising an aperture disposed in the second mirror group. The zoom projection lens of claim 1, wherein the first mirror group comprises a first lens, a second lens, a third lens, and a first one arranged in sequence from the imaging side to the image source side. Four lenses and a fifth lens; the lenses are all made of glass, and their refractive powers are negative, positive, negative, negative, and positive. The zoom projection lens of claim 1, wherein the second lens group is a glass lens having a positive refractive power from the imaging side to the image source side. The zoom projection lens of claim 1 further satisfies the following condition: -0.87<f2/f1<-0.76, wherein f1 is the effective focal length of the first mirror group; and f2 is the effective focal length of the second mirror group. The zoom projection lens according to claim 1 further satisfies the following condition: -2.09<f1/fw<-1.85, wherein f1 is the effective focal length of the first mirror group; fw is the zoom projection lens at the wide angle (wide- Effective focal length in the angle state. The zoom projection lens of claim 1 further satisfies the following condition: 1.59<f2/fw<1.64, wherein f2 is an effective focal length of the second mirror group; fw is the zoom projection lens at a wide-angle Effective focal length in the state. The zoom projection lens according to claim 1 further satisfies the following condition: 0.70<fw/bf<0.71, wherein fw is an effective focal length of the zoom projection lens in a wide-angle state; bf is the zoom projection The focal length of the lens. The zoom projection lens according to claim 1 further satisfies the following condition: 6.66<tt/fw<6.7, wherein fw is an effective focal length of the zoom projection lens in a wide-angle state; tt is the zoom projection The total length of the lens. The zoom projection lens of claim 1 further satisfies the following condition: 4.7 < tt / bf < 4.74, wherein bf is the focal length of the zoom projection lens; tt is the total length of the zoom projection lens. The zoom projection lens according to claim 1 further satisfies the following condition: -1.31 <ex/bf<-1.24, wherein bf is the focal length of the zoom projection lens; ex is the exit position of the zoom projection lens (exit Pupill position). The zoom projection lens of claim 1 further satisfies the following conditions: 0.787<lt/tt<0.789, where tt is the total length of the zoom projection lens; lt is the length between the first surface and the last surface of the zoom projection lens.