TWI427319B - Miniature zoom lens - Google Patents

Description

Mini zoom lens

The invention relates to a miniature zoom lens, in particular to a miniature zoom lens which can be applied to a portable image capturing device such as a digital camera (DV) or a digital camera (DSC).

With the advancement of modern video technology, image devices such as projectors, digital cameras, and digital cameras have been widely used. One of the core components in these imaging devices is a miniature zoom lens, which enables images of different magnifications to be clearly imaged by the focal length change of the micro zoom lens. Therefore, the optical quality of the miniature zoom lens is closely related to the quality of image imaging.

Among them, conventional zoom lenses often use CCD or CMOS as image sensors that can achieve 3x zoom, such as the disclosed or approved patents US7106522, US7324288, US7339749, EP2015123, US2009/0034067, US2009/0034092, etc. Wait. The above patents all use a group of three groups of lenses, including a first lens group having negative refractive power, a second lens group having positive refractive power, and a first positive refractive power group. a three lens group, and the first lens group, the second lens group, and the third lens group are sequentially arranged from the object side to the imaging side of the zoom lens, respectively. However, some of the above patents have a design in which all three groups of lenses need to be moved, so the overall cost of the above conventional zoom lens is high. In addition, since the first lens group is a compensation group, such a zoom lens is difficult to fabricate.

In addition, some of the optical systems disclosed in the published or approved patents (for example, EP1726980, EP1959285, US7145730, US7436449, US2009/0052052) use a right angle 稜鏡, which is mainly used to rotate the original optical path direction by 90. Degree (also changing the optical axis path by 90 degrees), however, the above patents generally use too many lenses (more than 8 lenses) and are designed to move all three groups of lenses, so the above-mentioned conventional zoom lens The overall cost is higher.

Therefore, the present inventors have felt that the above-mentioned deficiencies can be improved, and based on years of experience in this field, carefully observed and studied, and in conjunction with the application of the theory, a present invention which is reasonable in design and effective in improving the above-mentioned defects is proposed.

The technical problem to be solved by the present invention is to provide a miniature zoom lens which has the characteristics of low cost, easy fabrication and easy assembly, and at the same time can meet the requirements of compact volume.

In order to solve the above technical problem, according to one aspect of the present invention, a miniature zoom lens includes: a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a A third lens group having positive refractive power. Wherein, the first lens group having the negative refractive power is fixed at a predetermined position. The second lens group having positive refractive power can move along the optical axis of the micro zoom lens as the magnification of the micro zoom lens changes. The third lens group having positive refractive power can be moved along the optical axis of the micro zoom lens to keep the imaging surface generated by the micro zoom lens accurately projected on an image recorder. In addition, the first lens group, the second lens group, and the third lens group are sequentially arranged along the optical axis and from the object side to the imaging side of the micro zoom lens, and the first lens group And the focal length of the second lens group must meet the following two sets of conditions: condition (1): ; and condition (2): Wherein F1 is the focal length of the first lens group, F2 is the focal length of the second lens group, F _W is the focal length of the optical system in the wide-angle state, and F _T is the focal length of the optical system in the telephoto state.

Therefore, the beneficial effects of the present invention are:

1. The micro zoom lens of the present invention uses only three groups of lens groups, and the micro zoom lens of the present invention has an internal focusing structure. In other words, in the zooming process of the micro zoom lens of the present invention, the first lens group is in a stationary state, and only the second lens group and the third lens group are moved, so that the present invention can achieve cost reduction. Easy to make and assemble simple features.

2, the miniature zoom lens of the present invention, the diaphragm may vary with different F _NO which image capture applications. For example, when shooting a motion picture requires a large amount of light, a smaller F _NO can be used; when a still image is required and a higher resolution is required, a larger F _NO can be used.

3. In the micro zoom lens of the present invention, the first lens group can use at least 3 lenses, the second lens group can use at least 3 lenses, and the third lens group can use at least 1 lens. Therefore, the total number of lenses used in the first lens group, the second lens group, and the third lens group may be at least 7 pieces, so that the cost can be reduced, and the assembly and assembly can be simplified. Characteristics.

For a better understanding of the features and technical aspects of the present invention, reference should be made to the accompanying drawings.

Please refer to FIG. 1A to FIG. 1C, which respectively show the lens groups of the micro zoom lens according to the first embodiment of the present invention at the wide angle end (first A picture) and the standard position (Normal). (first B picture) and telephoto (Tele) (first C picture) lens configuration diagram in three types, wherein D1 to D15 in the first A picture indicate the axial distance between the optical surfaces, first S1 to S15 in the figure B are the optical surface numbers of the respective lenses.

The micro zoom lens of the first embodiment of the present invention can be composed of seven lenses. The micro zoom lens of the first embodiment of the present invention includes: a first lens group G1 and a second lens group G2, and the lens assembly configuration relationship disclosed in the first embodiment of FIG. A third lens group G3, wherein the first lens group G1 has a negative refractive power, and the second lens group G2 and the third lens group G3 each have a positive refractive power. Using the first lens group G1, the second lens group G2, and the third lens group G3 to change from each other (that is, by changing the spacing between the lens groups along the optical axis Z direction) , you can change the focal length of this miniature zoom lens.

In the first embodiment of the present invention, the first lens group G1 includes a first lens L _11, L ₁₂ and the right angle Prism a second lens L _13. The second lens group G2 includes a first lens L ₂₁ , a second lens L ₂₂ and a third lens L ₂₃ . The third lens group G3 is a single first lens L ₃₁ . In addition, a front of the first lens L ₂₁ of the second lens group G2 is a stop A that can move along with the second lens group G2 (that is, the stop A is disposed in the first lens group). Between G1 and the second lens group G2, and movable along with the second lens group G2, and the size of the aperture A can be adjusted as needed for use.

In other words, the first lens group G1 having the negative refractive power is fixed at a predetermined position. The second lens group G2 having positive refractive power can move along the optical axis Z of the micro zoom lens as the magnification of the micro zoom lens changes. The third lens group G3 having the negative refractive power can be moved along the optical axis Z of the micro zoom lens to keep the imaging surface generated by the micro zoom lens accurately projected on the image recorder 1. In addition, the first lens group G1, the second lens group G2, and the third lens group G3 are sequentially arranged along the optical axis Z and from the object side to the imaging side of the micro zoom lens.

For example, in order to achieve compactness and maintain image quality, the focal length of the first lens group G1 and the second lens group G2 must meet the following two conditions: condition (1): ; and condition (2): Wherein F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, F _W is the focal length of the optical system in the wide-angle state, and F _T is the focal length of the optical system in the telephoto state.

Further, regarding the first lens group G1, the first lens L ₁₁ includes a first lens L ₁₁ , a right angle disposed on one side of the first lens L ₁₁ and used to change the path of the optical axis Z by 90 degrees.稜鏡L ₁₂ and a second lens L ₁₃ disposed on one side of the right angle 稜鏡L ₁₂ and having positive refractive power. for example:

(1) The focal lengths of the first lens L ₁₁ and the second lens L ₁₃ of the first lens group G1 are subject to the following conditions:

Wherein F _{11 is} the focal length of the first lens L ₁₁ of the first lens group G1, and F _{12 is} the focal length of the second lens L ₁₃ of the first lens group G1.

(2) The first lens group G1 may be a front fixed group, the first lens L _{11 of} the first lens group G1 may be a meniscus, and the first lens group The second lens L _{13 of} G1 may be a biconvex lens.

(3) The first lens L ₁₁ and the second lens L _{13 of} the first lens group G1 may be made of a glass material having a refractive index greater than 1.8.

In addition, the second lens group G2 includes: a first lens L ₂₁ , a second lens L ₂₂ disposed on one side of the first lens L ₂₁ , and a second lens L disposed on the second lens L a third side of the lens L _{23 22,} the second lens group G2 of the first lens L _21, a second lens L ₂₂ L ₂₃ and the third lens along the optical axis Z from the miniature zoom lens and The object side to the imaging side are sequentially arranged. for example:

(1) The focal lengths of the second lens L ₂₂ and the third lens L ₂₃ of the second lens group G2 are subject to the following conditions: Wherein F _{22 is} the focal length of the second lens L ₂₂ of the second lens group G2, and F _{23 is} the focal length of the third lens L ₂₃ of the second lens group G2.

(2) The second lens group G2 may be a zoom group, the first lens L _{21 of} the second lens group G2 may be a monolithic convex lens, and the second lens group G2 is second. The lens L ₂₂ and the third lens L ₂₃ may be two meniscus lenses separated from each other by a predetermined distance and used for controlling field curvature and axial chromatic aberration, respectively, and the positive refractive power and negative refractive power of each meniscus lens. The focal length ratio of the ability is approximately 1:2.

(3) The focal length of the first lens L ₂₁ of the second lens group G2 and the focal length ratio of the second lens group G2 are approximately:

Where F _{21 is} the focal length of the first lens L ₂₁ of the second lens group G2, and F2 is the focal length of the second lens group G2.

(4) The third lens L _{23 of} the second lens group G2 may be made of a glass material having a refractive index greater than 1.8 and an Abbe number less than 30.

(5) The focal length of the second lens group G2 may be 0.3 to 0.35 of the total length of the system of the micro zoom lens.

In addition, the micro zoom lens of the first embodiment of the present invention can be applied to an image capturing device (for example, a conventional camera, a digital camera, a digital camera, etc.). In other words, the micro zoom lens composed of the first lens group G1, the second lens group G2, and the third lens group G3 can be assembled in the image capturing device.

Referring to the first D diagram to the first F diagram, the first D diagram represents the astigmatism and field curvature diagram of the first embodiment in the wide-angle mode; the first E diagram represents the first embodiment in the standard position pattern. The astigmatism and field curvature map of the time; the first F diagram shows the astigmatism and field curvature diagram of the first embodiment in the telephoto mode.

The data of the first embodiment of the present invention is shown in the following table, where R represents the radius of curvature of each lens surface (numbered from S1 to S19), and D represents the axial distance between the optical surfaces (numbered from D1 to D19). , n _d represents the refractive index of each optical surface, and V _d represents the Abbe value of each optical surface (a value indicating the chromatic dispersion characteristic of the material).

The relationship of variables D7, D13 and D19 with respect to different zoom positions are as follows:

Where f denotes the focal length of the system corresponding to the wide-angle end, the standard end and the telephoto end, F _NO denotes the pupil aperture corresponding to the wide-angle end, the standard end and the telephoto end, and FOV(ω) denotes the angle of view corresponding to the wide-angle end, the standard end and the telephoto end.

Further, in the lenses, the optical surface numbers S3, S4, S8 to S11, and S14 to S15 are aspherical surfaces, and the aspherical coefficient data are as follows:

The above aspherical equation in the radial direction can be expressed as:

Wherein, Z is a sag, C (=1/r) is a spherical curvature, K is a conic constant, Y is a height perpendicular to the optical axis Z of the lens, A ₄ is a fourth-order aspheric coefficient, and A ₆ is The 6th-order aspheric coefficient, the representative of A ₈ to A ₁₆ and so on.

Please refer to FIG. 2A to FIG. 2C, which respectively show the lens groups of the micro zoom lens according to the second embodiment of the present invention at the wide angle end (second A picture) and the standard position (second B picture). And a schematic diagram of lens configuration in three types of telescopes (second C diagram). The greatest difference between the second embodiment and the first embodiment is that the second lens group G2 in the second embodiment has a fourth lens L ₂₄ , so that the micro zoom lens of the second embodiment of the present invention can be made up of 8 lenses. Composed of.

Please refer to the second D diagram to the second F diagram, the second D diagram shows the astigmatism and field curvature diagram of the second embodiment in the wide-angle mode; the second E diagram shows the second embodiment in the standard position pattern. The astigmatism and field curvature map of the time; the second F diagram shows the astigmatism and field curvature diagram of the second embodiment in the telephoto mode.

Please refer to the following table for the data of the second embodiment of the present invention:

The relationship of variables D6, D15 and D17 with respect to different zoom positions are as follows:

Furthermore, in these lenses, the optical surface numbers S3, S4, S8 to S11, and S14 to S17 are aspherical surfaces, and the aspherical coefficient data are as follows:

The above equation of the aspherical surface in the radial direction is the same as that of the first embodiment of the present invention.

Please refer to FIG. 3A to FIG. 3C, which respectively show the lens groups of the micro zoom lens according to the third embodiment of the present invention at the wide angle end (third A picture) and the standard position (third B picture). And the telescopic configuration of the three types of teledes (the third C picture). Therefore, the third embodiment is the same as the first embodiment and is composed of seven lenses.

Please refer to the third D to the third F, the third D diagram shows the astigmatism and field curvature diagram of the third embodiment in the wide-angle mode; the third E diagram shows the third embodiment in the standard position pattern. The astigmatism and field curvature map of the time; the third F diagram shows the astigmatism and field curvature diagram of the third embodiment in the telephoto mode.

Please refer to the following table for the data of the third embodiment of the present invention:

The relationship of the variables D6, D13 and D15 with respect to different zoom positions is as follows:

Further, in the lenses, the optical surface numbers S3, S4, S8 to S11, and S14 to S15 are aspherical surfaces, and the aspherical coefficient data are as follows:

The above aspherical equation in the radial direction can be expressed as: Wherein, Z is a sag, C (=1/r) is a spherical curvature, K is a conic constant, Y is a height perpendicular to the optical axis Z of the lens, A ₄ is a fourth-order aspheric coefficient, and A ₆ is The 6th-order aspheric coefficient, the representative of A ₈ to A ₂₀ and so on.

Thereby, the first to third embodiments of the present invention described above are collated as shown in the following table:

Wherein F1 is the focal length of the first lens group G1, F2 is the focal length of the second lens group G2, F _W is the focal length of the optical system in the wide-angle state, and F _T is the focal length of the optical system in the telephoto state, F ₁₁ The focal length of the first lens L ₁₁ of the first lens group G1, F _{12 is} the focal length of the second lens L ₁₃ of the first lens group G1, and F _{22 is} the second lens of the second lens group G2 a focal length of L ₂₂ , F _{23 is} the focal length of the third lens L ₂₃ of the second lens group G2, F _{21 is} the focal length of the first lens L ₂₁ of the second lens group G2, and V _{11 is} the first lens Abbe number of the first lens L ₁₁ of the group G1, V _{13 is} the Abbe number of the second lens L ₁₃ of the first lens group G1, and V _{22 is} the second lens L of the second lens group G2 Abbe number of ₂₂ , V _{23 is} the Abbe number of the third lens L ₂₃ of the second lens group G2, N _{11 is} the refractive index of the first lens L ₁₁ of the first lens group G1, and N ₁₃ is The refractive index of the second lens L ₁₃ of the first lens group G1, N _{23 is} the refractive index of the third lens L ₂₃ of the second lens group G2, and TTL is the total length of the system of the zoom lens.

In summary, the features and functions that can be produced by the present invention are as follows:

1. The micro zoom lens of the present invention uses only three groups of lens groups, and the micro zoom lens of the present invention has an internal focusing structure. In other words, in the zooming process of the micro zoom lens of the present invention, the first lens group is in a stationary state, and only the second lens group and the third lens group are moved, so that the present invention can achieve cost reduction. Easy to make and assemble simple features.

2, the miniature zoom lens of the present invention, the diaphragm may vary with different F _NO which image capture applications. For example, when shooting a motion picture requires a large amount of light, a smaller F _NO can be used; when a still image is required and a higher resolution is required, a larger F _NO can be used.

3. In the micro zoom lens of the present invention, the first lens group can use at least 3 lenses, the second lens group can use at least 3 lenses, and the third lens group can use at least 1 lens. Therefore, the total number of lenses used in the first lens group, the second lens group, and the third lens group may be at least 7 pieces, so that the cost can be reduced, and the assembly and assembly can be simplified. Characteristics.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalents of the invention are included in the scope of the invention.

G1. . . First lens group

L ₁₁ . . . First lens

L ₁₂ . . . Right angle 稜鏡

L ₁₃ . . . Third lens

G2. . . Second lens group

L ₂₁ . . . First lens

L ₂₂ . . . Second lens

L ₂₃ . . . Third lens

L ₂₄ . . . Fourth lens

G3. . . Third lens group

L ₃₁ . . . First lens

S1 to S17. . . Optical surface

D1 to D17. . . Axial distance

A. . . Light

I. . . Image recorder

Z. . . Optical axis

FIG. 1A to FIG. 1C respectively show lens configurations of the lens groups of the micro zoom lens according to the first embodiment of the present invention in three types of wide angle, standard position, and telephoto;

The first D map to the first F graph respectively show astigmatism and field curvature diagrams of the first embodiment in a wide-angle mode, a standard position type, and a telephoto type;

2A to 2C are schematic diagrams showing lens configurations of the lens groups of the micro zoom lens according to the second embodiment of the present invention in three types of wide angle, standard position and telephoto;

The second D map to the second F graph respectively show astigmatism and field curvature diagrams of the second embodiment in the wide-angle mode, the standard position type, and the telephoto type;

3A to 3C are schematic diagrams showing lens configurations of the lens groups of the micro zoom lens according to the third embodiment of the present invention in three types of wide angle, standard position, and telephoto;

The third to third F diagrams respectively show astigmatism and field curvature diagrams of the third embodiment in the wide-angle mode, the standard position type, and the telephoto mode.

G1. . . First lens group

L ₁₁ . . . First lens

L ₁₂ . . . Right angle 稜鏡

L ₁₃ . . . Third lens

G2. . . Second lens group

L ₂₁ . . . First lens

L ₂₂ . . . Second lens

L ₂₃ . . . Third lens

G3. . . Third lens group

L ₃₁ . . . First lens

D1 to D15. . . Axial distance

A. . . Light

I. . . Image recorder

Z. . . Optical axis

Claims (10)

A miniature zoom lens comprising: a first lens group having a negative refractive power fixed to a predetermined position; and a second lens group having a positive refractive power, along with the miniature zoom lens a magnification of the magnification moves along the optical axis of the micro zoom lens; and a third lens group having a positive refractive power that moves along the optical axis of the micro zoom lens to maintain the micro zoom lens The imaging surface is accurately projected onto an image recorder; wherein the first lens group, the second lens group and the third lens group are along the optical axis and from the object side of the micro zoom lens to imaging The sides are sequentially arranged, and the focal lengths of the first lens group and the second lens group are subject to the following two conditions: condition (1): ; and condition (2): ; Wherein, for the focal length Fl of the first lens group, F2 for the focal length of the second lens group, the focal length of the wide-angle state when the optical system F _W, F _T is a focal length and the telephoto state of the optical system. The micro zoom lens according to claim 1 , further comprising: a diaphragm whose diameter is adjustable, and the aperture is disposed along the optical axis and disposed on the first lens group and the second lens Between groups. The micro zoom lens of claim 1, wherein the first lens group comprises: a first lens, a side disposed on the first lens and configured to change a path of the optical axis by 90 a right angle 稜鏡, and a second lens disposed on one side of the right angle 且 and having a positive refractive power, and the focal lengths of the first lens and the second lens of the first lens group are required to meet the following condition: Wherein F _{11 is} the focal length of the first lens of the first lens group, and F _{12 is} the focal length of the second lens of the first lens group. The micro zoom lens according to claim 3, wherein the first lens group is a front fixed group, the first lens of the first lens group is a meniscus lens, and the first lens The second lens of the group is a lenticular lens. The micro zoom lens of claim 3, wherein the first lens and the second lens of the first lens group are made of a glass material having a refractive index greater than 1.8. The micro zoom lens of claim 1, wherein the second lens group comprises: a first lens, a second lens disposed on one side of the first lens, and a second lens disposed on the first lens a third lens on one side of the second lens, the first lens, the second lens and the third lens of the second lens group are arranged along the optical axis and sequentially from the object side to the imaging side of the micro zoom lens, And the focal length of the second lens and the third lens of the second lens group are subject to the following conditions: Wherein F _{22 is} the focal length of the second lens of the second lens group, and F _{23 is} the focal length of the third lens of the second lens group. The micro zoom lens of claim 6, wherein the second lens group is a zoom group, the first lens of the second lens group is a monolithic convex lens, and the second lens The second lens and the third lens of the group are two meniscus lenses that are separated from each other by a predetermined distance and used to control field curvature and axial chromatic aberration, respectively. The micro zoom lens according to claim 6, wherein a focal length of the first lens of the second lens group and a focal length ratio of the second lens group are: Wherein F _{21 is} the focal length of the first lens of the second lens group, and F2 is the focal length of the second lens group. The micro zoom lens of claim 6, wherein the third lens of the second lens group is made of a glass material having a refractive index of between 1.8 and 30. The micro zoom lens according to claim 1, wherein the focal length of the second lens group is 0.3 to 0.35 of the total length of the system of the micro zoom lens.