TWI805585B - Zoom lens - Google Patents

Abstract

A zoom lens from a magnified side to a reduced side substantially only including a first to a fourth lens sets is provided. Three of the lens sets are movable. The first lens set is movable. When the zoom lens is zooming, the three movable lens sets are able to move. The total track length of the zoom lens is T. An image height of the zoom lens is H. The zoom lens meets the following condition expression: T/H≦25. Furthermore, another zoom lens is also provided.

Description

zoom lens

The present invention relates to a lens, and in particular to a zoom lens.

In a general zoom lens, a plurality of lenses arranged in the lens are usually grouped, and these lens groups (for example, more than five lens groups) are moved correspondingly according to zooming or focusing requirements. However, the above-mentioned multi-lens group design increases the difficulty and cost of lens manufacturing and makes it impossible to reduce the size of the lens. Therefore, how to manufacture a zoom lens with low cost, small size and good imaging quality is one of the important tasks for those skilled in the art.

In one example of the present invention, a zoom lens is provided, which can use fewer lens groups to achieve better imaging quality.

Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the embodiments of the present invention.

In one embodiment of the present invention, a zoom lens is proposed. When applied in a projector, it is calculated from the light output side (or called the magnification side, or the side close to the direction of the projection screen) to the light input side ( The reduction side, close to the image plane) is grouped according to the mobility of the lens in sequence, and four lens groups are arranged, which are respectively called the first, second, third and fourth lens groups in sequence. The lens closest to the magnification side in the first lens group is an aspherical lens. When the zoom lens zooms, the four lens groups include at least three movable lens groups. For example, in this example, when zooming, the first, second and third lens groups move relative to the imaging surface, while the fourth lens group is fixed relative to the imaging surface. In addition, the total lens length of the zoom lens divided by the image height of the zoom lens is less than or equal to 25. With the design of the embodiment of the present invention, the zoom lens can achieve the zoom function with fewer lens groups and at least three movable lens groups, and its manufacturing difficulty is relatively simple and has a lower manufacturing cost, and the total length is divided by When the image height ratio is 25 or below, its size can be reduced.

In one embodiment of the present invention, a zoom lens is proposed. When applied in a projector, it is counted from the output side of the light (or called the enlargement side, or the side close to the direction of the projection screen) to the input side of the light (zoom out). Side) grouped according to the mobility of the lens, there are four lens groups arranged, which are respectively called the first, second, third and fourth lens groups in sequence. The lens closest to the magnification side in the first lens group is an aspherical lens with negative diopter. The lens closest to the magnification side in the first lens group is an aspherical lens. When the zoom lens zooms, the four lens groups include at least three movable lens groups. For example, in this example, when zooming, the first, second and third lens groups move relative to the imaging surface, while the fourth lens group is fixed relative to the imaging surface. In addition, the zoom lens includes more than 12 lenses with non-zero diopters.

Through the design of the embodiment of the present invention, the zoom lens can realize the zoom function with less lens groups and at least three movable lens groups, and its manufacturing difficulty is relatively simple and has a low manufacturing cost. The zoom lens of this example Variable lenses include more than 12 lenses with diopters.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the embodiments with reference to the drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only directions referring to the attached drawings. Accordingly, the directional terms used are for the purpose of illustration and not for the purpose of limiting the invention.

With the design of the embodiments of the present invention, a zoom lens with a simple design and better imaging quality can be provided.

Fig. 1 A is the schematic diagram of the zoom lens of the first embodiment of the present invention; Fig. 1 B is the relative position of the zoom lens of the first embodiment of the present invention at the wide-angle end (WIDE), the intermediate end (MID), and the telephoto end (TELE) schematic diagram.

The zoom lens 100 may, for example, be suitable for an optical system, and the optical system may be an image capturing device of a projector 1 or a camera. In this example, the optical system is a projector 1 using a telecentric zoom lens 100 .

In this example, the projector 1 includes an illumination system IS, an optical lens group OA, a light valve LV, a transmissive smooth picture device (Transmissive Smooth Picture, TSP) and a zoom lens 100 .

The illumination system IS, the light valve LV, the optical lens group OA, and the transmissive smooth image device TSP are arranged between the reduction side RS and the lens. The illumination system 10 is used for providing an illumination beam IB to the light valve LV.

The light valve LV can be any one of spatial light modulators such as a digital micromirror device (DMD), a liquid crystal on silicon panel (LCOS), or a transmissive liquid crystal panel (LCD). The optical beam group OA is arranged on the transmission path IB of the illumination beam IB. The illuminating light beam IB is totally reflected by the optical beam group OA, and then goes to the light valve LV. When the light valve LV is a DMD, multiple micro-mirrors on its surface are located on the image plane of the lens to convert the illumination beam IB into the image beam IMB. The image beam IMB sequentially penetrates the optical beam group OA, enters the zoom lens 100 through the transmissive smooth image device TSP, and forms an image at the focal point of the magnifying side MS after passing through the zoom lens 100 .

Transmissive smooth image device TSP is a widely used optical element, which includes a swingable plate glass, which can be used to improve the resolution.

As mentioned above, the zoom lens 100, for example, can be used to take an image, and the photosensitive element (not shown) can be arranged at the position of the light valve LV on the reduction side RS to replace the light valve LV, and the position of the image plane of the zoom lens 100 Then for example the position of the surface S28 of the light valve LV shown in the drawing. At this time, the image plane is located on the surface of the photosensitive element.

Please refer to FIG. 1A and FIG. 1B. In this example, the zoom lens 100 has an optical axis I, and along the optical axis I includes a first lens group G1, a second lens group G2, and an aperture from the zoom side MS to the zoom side RS. S, the third lens group G3 and the fourth lens group G4 . The aforementioned lens groups G1 - G4 respectively include at least one or more lenses with refractive power. If the lens group has multiple lenses, these lenses will move together when the lens group moves, and the distance between any two adjacent lenses in the lens group will not change with the adjustment of the focal length of the zoom lens 100 . That is, each lens group is grouped according to its mobility. In this example, the zoom lens 100 includes three movable lens groups. When the zoom lens 100 zooms (Zoom), the first lens group G1, the second lens group G2, and the third lens group G3 are on the optical axis I relative to the operating surface or image plane on the light valve LV (the same below) Move each to switch between wide-angle end, intermediate end, and telephoto end for zoom operation (Zoom). When focusing (FOCUS), the first lens group G1 moves to focus, while the fourth lens group G4 remains stationary relative to the actuating surface of the light valve LV during zooming and focusing.

Please refer to FIG. 1B , when the zoom lens 100 is switched from the wide-angle end to the middle end, the first lens group G1, the second lens group G2, and the third lens group G3 move to the reduction side RS and the enlargement side along the optical axis I respectively. The MS and the magnifying side MS move, while the fourth lens group G4 and the aperture S are fixed relative to the actuating surface on the light valve LV. At this time, the variable distances D1 , D2 , D3 and D4 of the zoom lens 100 become smaller, larger, smaller and larger, respectively.

Please refer to FIG. 1B , when the zoom lens 100 is switched from the middle end to the telephoto end, the first lens group G1, the second lens group G2, and the third lens group G3 move to the reduction side RS and the enlargement side respectively along the optical axis I. The MS and the magnifying side MS move, while the fourth lens group G4 and the aperture S are fixed relative to the light valve LV. At this time, the variable distances D1 , D2 , D3 , and D4 of the zoom lens 100 become smaller, larger, smaller, and larger, respectively.

In addition, during the above zooming process, the aperture value of the aperture S is a constant value.

In this example, there are 13 lenses with diopters in the zoom lens 100 , including 2 aspheric lenses and 11 spherical lenses. The lens arrangement, diopter, material and lens type of each lens group G1 - G4 in the zoom lens 100 will be described in detail in the following paragraphs.

The first lens group G1 has a negative diopter and includes lenses L1, L2, L3, L4 and L5 along the optical axis I from the magnification side MS to the reduction side RS. The diopters are negative, negative, positive, negative, and positive, respectively. The lens L1 is a lens with a diopter closest to the magnification side MS in the first lens group G1, and its material is plastic, and it is an aspherical lens (Aspherical Lens). The lenses L2-L5 are all spherical lenses, and the materials of the lenses L2-L5 are all glass. The lenses L2 and L3 are cemented doublets.

The second lens group G2 has a positive diopter and includes a lens L6 having a positive diopter. The lens L6 is a spherical lens, and its material is glass.

The aperture S is disposed between the second lens group G2 and the third lens group G3. The aperture value (F-number) is less than or equal to 2, and is, for example, 1.7.

The third lens group G3 has a positive diopter, and includes lenses L7, L8, L9, L10, L11, L12 sequentially along the optical axis I from the magnification side MS to the reduction side RS, and their diopters are negative, positive, negative, and negative, respectively. , positive, positive. These lenses L7-L12 are all spherical lenses, and the materials of these lenses L7-L12 are all glass. Lenses L7, L8, L9 are triplet lenses. Lenses L10, L11 are doublet lenses.

The diopter of the fourth lens group G4 is positive, and includes the lens L13, and the diopter of the lens L13 is positive. The lens L13 is an aspherical lens, and its material is glass, which is made by hot pressing process.

It is worth noting that the two adjacent surfaces of the doublet or cemented lens mentioned in this example have the same or similar curvature radius, and the adjacent two surfaces of the doublet or cemented lens can use different radii of curvature. There is no limit to the method of lamination, such as optical glue coating between two adjacent surfaces, and mechanical components to press adjacent two surfaces.

In the zoom lens 100 , each lens has a convex, concave or plane facing the zooming side MS and allowing the imaging light to pass through, and a convex, concave or flat reducing side facing the reducing side RS and allowing the imaging light to pass through. The corresponding surface shapes of the above elements will be described in detail in the following paragraphs.

In the first lens group G1 , the lens L1 has a convex surface S1 on the enlargement side and a concave surface S2 on the reduction side. The lens L2 has an enlargement-side concave surface S3 and a reduction-side concave surface (not shown). The lens L3 has an enlargement-side convex surface S4 and a reduction-side convex surface S5. The lens L4 has an enlargement-side concave surface S6 and a reduction-side concave surface S7. The lens L5 has an enlargement-side convex surface S8 and a reduction-side convex surface S9.

In the second lens group G2, the lens L6 has a convex surface S10 on the enlargement side and a flat surface S11 on the reduction side.

S12 is aperture S. In this example, the aperture S aperture is a fixed aperture, which is usually a mechanism or structural member with a light-transmitting hole of a fixed size in the middle; but if necessary, it can be replaced by an adjustable aperture such as IRIS.

In the third lens group G3, the lens L7 has an enlargement-side convex surface S13 and a reduction-side concave surface (not shown). The lens L8 has an enlargement-side convex surface S14 and a reduction-side convex surface (not shown). The lens L9 has an enlargement-side concave surface S15 and a reduction-side convex surface S16. The lens L10 has an enlargement-side concave surface S17 and a reduction-side concave surface (not shown). The lens L11 has an enlargement-side convex surface S18 and a reduction-side convex surface S19. The lens L12 has an enlargement-side convex surface S20 and a reduction-side convex surface S21.

In the fourth lens group G4, the lens L13 has an enlargement-side convex surface S22 and a reduction-side convex surface S23.

The transmissive smooth image device TSP has an enlargement side surface S24 and a reduction side surface S25. The optical lens group OA has an enlargement side surface S26 and a reduction side surface S27. The light valve LV has an enlargement side surface S28 and a reduction side surface S29.

The lens design parameters of the zoom lens 100 , the design parameters of the optical lens group OA and the light valve LV are shown in Table 1 below. The design parameters and related optical parameters of the zoom lens 100 at the wide-angle end, intermediate end, and telephoto end corresponding to the variable distances D1 - D4 are shown in Tables 2 and 3 below. The effective focal lengths (Effective Focal Length, EFL) of each lens group G1~G4 are shown in Table 4 below. Table 5 shows related optical data of the zoom lens 100 of this embodiment, wherein the image height H can be half the length of the diagonal of the light valve LV actuating surface. The total lens length T (TTL) mentioned in Table 5 refers to the maximum distance along the optical axis between the two diopter lenses that are farthest apart along the optical axis in the zoom lens when the lens is at the wide-angle end. In this example, the total length of the lens is, for example, the distance measured from the surface S1 of the lens L1 facing the magnification side MS to the surface S23 on the optical axis I and at the wide-angle end. However, the information listed below is not intended to limit the present invention. Anyone with ordinary knowledge in the field may make appropriate changes to its parameters or settings after referring to the present invention, but it should still fall within the scope of the present invention . The * symbol in the surface column means that it is an aspheric surface; if there is no surface, it is a spherical surface.

表二

表三

表四

表五

Table I

Table II

Table three

Table four

Table five

…(1)Furthermore, in each of the following design examples of the present invention, the aspheric polynomial can be expressed by the following formula:

…(1)

In the above formula (1), x is the offset in the direction of the optical axis I (sag), c' is the reciprocal of the radius of the Osculating Sphere, that is, the reciprocal of the radius of curvature near the optical axis I, k is the quadratic surface coefficient, and y is the height of the aspheric surface, that is, the height from the center of the lens to the edge of the lens. AE respectively represent the aspheric coefficients of each order of the aspheric polynomial. Table 6 below lists the aspheric coefficients and quadric coefficient values of each order of S1, S2, S22, and S23. Table six

It must be noted here that the following embodiments continue to use part of the content of the previous embodiments, omitting the description of the same technical content. For the same component names, reference can be made to part of the content of the previous embodiments, and the following embodiments will not be repeated.

FIG. 2A is a schematic diagram of a zoom lens according to a second embodiment of the present invention. 2B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the second embodiment of the present invention. In order to clearly illustrate the action relationship between the lens groups, Figure 2B shows the zoom lens in a horizontal manner, and the zoom lens shown in a horizontal manner is optically equivalent to the L-shaped zoom lens in Figure 2A, and so on hereinafter .

Please refer to FIG. 2A. In this example, the zoom lens 100a is substantially similar to the zoom lens 100. The main difference is that the zoom lens 100a sequentially includes a first lens group G1a, The second lens group G2a, the third lens group G3a, the aperture S and the fourth lens group G4a. In addition, a reflective element R is provided on the optical path between the lens L7 and the aperture S. In this embodiment, the reflective element R is a reflective smooth image device (Reflective Smooth Picture, RSP), but it can be a reflective mirror or other light-emitting devices. Elements of the guidance function replace it. Furthermore, the reflective element R can also be omitted so that the light path can travel without turning, and the present invention is not limited thereto. The zoom lens 100a can be turned into an L shape. In this example, when the zoom lens 100a is zoomed, the first lens group G1a, the second lens group G2a, the third lens group G3a, and the fourth lens group G4a move on the optical axis I respectively, so that at the wide-angle end, the middle The zoom operation is performed by switching between the telephoto end and the telephoto end, and the fourth lens group G4a moves on the optical axis I when focusing.

Please refer to FIG. 2B , when the zoom lens 100a is switched from the wide-angle end to the middle end, the first lens group G1a, the second lens group G2a, and the third lens group G3a respectively go to the reduction side RS and the enlargement side along the optical axis I. MS and the magnification side MS move, and the fourth lens group G4a moves along the optical axis I to the magnification side MS for focusing operation, and the aperture S is fixed relative to the actuating surface on the light valve LV. At this time, the variable distances D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

Please refer to FIG. 2B , when the zoom lens 100a is switched from the middle end to the telephoto end, the first lens group G1a, the second lens group G2a, and the third lens group G3a respectively go to the reduction side RS and the enlargement side along the optical axis I. MS and the zoom side MS move, while the fourth lens group G4a moves along the optical axis I to the zoom side MS for focusing operation, and the aperture S is fixed relative to the actuating surface on the light valve LV. At this time, the variable distances D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

In addition, during the above zooming process, the aperture value of the aperture S is a constant value.

In this example, there are 12 lenses with diopters in the zoom lens 100a, including 1 aspheric lens and 11 spherical lenses. The lens arrangement, diopter, material and lens type of each lens group G1 a - G4 a in the zoom lens 100 a will be described in detail in the following paragraphs.

The diopter of the first lens group G1a is negative, and sequentially includes lenses L1, L2, L3 along the optical axis I from the magnification side MS to the reduction side RS, and the diopters of these lenses L1, L2, and L3 are negative, negative, and positive, respectively. . The lens L1 is made of plastic and is an aspherical lens. Lenses L2, L3 are doublet lenses. The materials of the lenses L2 and L3 are both glass, and both are spherical lenses.

The second lens group G2a has a negative diopter and sequentially includes lenses L4 and L5 along the optical axis I from the magnification side MS to the reduction side RS. The diopters of the lenses L4 and L5 are negative and positive respectively. Lenses L4, L5 are doublet lenses. Both lenses L4 and L5 are made of glass, and both are spherical lenses.

The third lens group G3a has a positive diopter and includes a lens L6 having a positive diopter. The lens L6 is made of glass and is a spherical lens.

The aperture S is disposed between the third lens group G3a and the fourth lens group G4a.

The diopter of the fourth lens group G4a is positive, and includes lenses L7, L8, L9, L10, L11, L12, and the diopters of these lenses L7, L8, L9, L10, L11, L12 are respectively negative, positive, negative, negative , positive, positive. Lenses L7, L8, L9 are triplet lenses. Lenses L10, L11 are doublet lenses. The materials of the lenses L7-L12 are all glass, and all are spherical lenses.

The lens surface shapes of the above-mentioned lens groups G1a to G4a can be obtained from the table below and the figure, and will not be repeated here.

The lens design parameters of the zoom lens 100 a and the design parameters of the optical lens group OA and the light valve LV are shown in Table 7 below. The design parameters of the variable distances D1 - D5 corresponding to the wide-angle end, the intermediate end, and the telephoto end of the zoom lens 100 a and related optical parameters are shown in Tables 8 and 9 below. The effective focal lengths of each lens group G1a~G4a are shown in Table 10 below. Table 11 shows related optical data of the zoom lens 100a of this embodiment, wherein the image height H can be half the length of the diagonal of the light valve LV. The total length of the lens mentioned in Table 11 can be the distance measured from the surface S1 of the lens L1 facing the magnifying side MS to the surface S20 on the optical axis I at the wide-angle end.

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表九

表十

表十一

Table Seven

table eight

Table nine

table ten

Table Eleven

Table 12 below lists the aspheric coefficients and quadric surface coefficient values of each order of S1 and S2, and the aspheric surface equation can refer to formula (1). Table 12

FIG. 3A is a schematic diagram of a zoom lens according to a third embodiment of the present invention. 3B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the third embodiment of the present invention.

Please refer to FIG. 3A and FIG. 3B , the zoom lens 100b sequentially includes a first lens group G1b, a second lens group G2b, a third lens group G3b, an aperture S and a fourth lens along the optical axis I from the enlargement side MS to the reduction side RS. Group G4b. In this example, when the zoom lens 100b zooms, the first lens group G1b, the second lens group G2b, and the third lens group G3b move on the optical axis I respectively, so as to be between the wide-angle end, the middle end, and the telephoto end. switch for zooming operation, and the fourth lens group G4b moves on the optical axis I for focusing operation.

Please refer to FIG. 3B , when the zoom lens 100b is switched from the wide-angle end to the intermediate end, the first lens group G1b, the second lens group G2b, and the third lens group G3b are respectively along the optical axis I relative to the light valve LV. The actuating surface (the same below) moves toward the reduction side RS, the enlargement side MS, and the enlargement side MS to perform the zoom operation, while the fourth lens group G4a moves to the enlargement side MS along the optical axis I to perform the focus adjustment operation, and the aperture S is relatively The actuating surface on the light valve LV is stationary. At this time, the variable distances D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

Please refer to FIG. 3B , when the zoom lens 100b is switched from the middle end to the telephoto end, the first lens group G1b, the second lens group G2b, and the third lens group G3b move to the reduction side RS and the enlargement side along the optical axis I respectively. MS and magnification side MS move for zooming operation, while fourth lens group G4b moves along optical axis I to magnification side MS for focusing operation, and aperture S is fixed relative to the actuating surface on light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

In addition, during the above zooming process, the aperture value of the aperture S is a constant value.

In this example, there are 14 lenses with diopters in the zoom lens 100b, including 1 aspheric lens and 13 spherical lenses. The lens arrangement, diopter, material and lens type of each lens group G1 a - G4 a in the zoom lens 100 a will be described in detail in the following paragraphs.

The diopter of the first lens group G1b is negative, and includes lenses L1, L2, L3, and L4 sequentially along the optical axis I from the magnification side MS to the reduction side RS, and the diopters of these lenses L1, L2, L3, and L4 are respectively negative. , negative, negative, positive. The lens L1 is made of plastic and is an aspherical lens. Lenses L3, L4 are doublet lenses. The materials of the lenses L2, L3, and L4 are all glass, and all are spherical lenses.

The second lens group G2b has a negative diopter, and sequentially includes lenses L5 and L6 along the optical axis I from the magnification side MS to the reduction side RS. The diopters of the lenses L5 and L6 are negative and positive, respectively. Lenses L5, L6 are doublet lenses. Both lenses L5 and L6 are made of glass, and both are spherical lenses.

The third lens group G3b has a positive diopter and includes lenses L7 and L8. The diopters of the lenses L7 and L8 are positive and positive. The material of the lenses L7 and L8 is glass, and they are spherical lenses.

The aperture S is disposed between the third lens group G3b and the fourth lens group G4b.

The diopter of the fourth lens group G4b is positive, and includes lenses L9, L10, L11, L12, L13, L14, and the diopters of these lenses L9, L10, L11, L12, L13, L14 are respectively negative, positive, negative, negative , positive, positive. The lenses L9, L10, and L11 are triplet lenses. Lenses L12, L13 are doublet lenses. The materials of the lenses L9-L14 are all glass, and all are spherical lenses.

The lens surface shapes of the above-mentioned lens groups G1b to G4b can be obtained from the following table and the figure, and will not be repeated here.

The lens design parameters of the zoom lens 100b and the design parameters of the optical lens group OA and the light valve LV are shown in Table 13 below. The design parameters and related optical parameters of the variable distances D1-D5 corresponding to the wide-angle end, intermediate end, and telephoto end of the zoom lens 100b are shown in Table 14 and Table 15 below. The effective focal lengths of each lens group G1b~G4b are shown in Table 16 below. Table 17 shows relevant optical data of the zoom lens 100b of this embodiment, wherein the image height H can be half the length of the diagonal of the light valve LV. The total length of the lens mentioned in Table 17 is the distance measured from the surface S1 of the lens L1 facing the magnification side MS to the surface S24 of the light valve LV on the optical axis I at the wide-angle end.

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表十七

Table 13

Table Fourteen

Table 15

Table 16

Table 17

Table 18 below lists the aspheric coefficients and quadratic coefficient values of each order of S1 and S2, and the aspheric equation can refer to formula (1). Table 18

FIG. 4A is a schematic diagram of a zoom lens according to a fourth embodiment of the present invention. 4B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the fourth embodiment of the present invention.

4A and 4B, the zoom lens 100c along the optical axis I sequentially includes a first lens group G1c, a second lens group G2c, a third lens group G3c, an aperture S and a fourth lens from the zoom side MS to the zoom side RS. Group G4c. In this example, when the zoom lens 100c zooms, the first lens group G1c, the second lens group G2c, the second lens group G2c, and the third lens group G3c move on the optical axis I respectively, so that the wide-angle end, the middle The zooming operation is performed by switching between the telephoto end and the telephoto end, and the fourth lens group G4c moves on the optical axis I to perform a focusing operation.

Please refer to FIG. 4B , when the zoom lens 100c is switched from the wide-angle end to the middle end, the first lens group G1c, the second lens group G2c, and the third lens group G3c move to the reduction side RS and the reduction side respectively along the optical axis I. RS and the zoom side MS move for zooming operation, while the fourth lens group G4c moves along the optical axis I to the zooming out side RS for focusing operation, and the aperture S is fixed relative to the actuating surface on the light valve LV. At this time, the variable distances D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

Please refer to FIG. 4B , when the zoom lens 100c is switched from the middle end to the wide-angle end, the first lens group G1c, the second lens group G2c, and the third lens group G3c respectively go to the reduction side RS and the enlargement side along the optical axis I. MS and magnification side MS move for zooming operation, while the fourth lens group G4c moves along optical axis I to magnification side MS for focusing operation, and aperture S is fixed relative to the actuating surface on light valve LV. At this time, the variable distances D1, D2, D3, D4, and D5 of the zoom lens become smaller, smaller, larger, smaller, and larger, respectively.

In addition, during the above zooming process, the aperture value of the aperture S is a constant value.

In this example, there are 15 lenses with diopters in the zoom lens 100c, including 1 aspheric lens and 14 spherical lenses. The lens arrangement, diopter, material and lens type of each lens group G1c - G4c in the zoom lens 100c will be described in detail in the following paragraphs.

The diopter of the first lens group G1c is negative, and sequentially includes lenses L1, L2, L3, L4 along the optical axis I from the magnification side MS to the reduction side RS, and the diopters of these lenses L1, L2, L3, L4 are respectively negative , negative, negative, positive. The lens L1 is made of plastic and is an aspherical lens. The materials of the lenses L2-L4 are all glass, and all are spherical lenses.

The diopter of the second lens group G2c is negative, and sequentially includes lenses L5 and L6 along the optical axis I from the magnification side MS to the reduction side RS. The diopters of the lenses L5 and L6 are negative and positive respectively. Lenses L5, L6 are doublet lenses. Both lenses L5 and L6 are made of glass, and both are spherical lenses.

The third lens group G3b has a positive diopter, and includes lenses L7, L8, L9, and the diopters of the lenses L7, L8, L9 are positive, positive, positive. The lenses L7-L9 are made of glass and are spherical lenses.

The aperture S is disposed between the third lens group G3c and the fourth lens group G4c.

The diopter of the fourth lens group G4c is positive, and includes lenses L10, L11, L12, L13, L14, L15, and the diopters of these lenses L10, L11, L12, L13, L14, L15 are respectively negative, positive, negative, negative , positive, positive. Lenses L10, L11, L12 are triplet lenses. Lenses L13, L14 are doublet lenses. The materials of the lenses L9-L15 are all glass, and all are spherical lenses.

The lens surface shapes of the above-mentioned lens groups G1d to G4d can be obtained from the table below and the figure, and will not be repeated here.

The lens design parameters of the zoom lens 100d and the design parameters of the optical lens group OA and the light valve LV are shown in Table 19 below. The design parameters and related optical parameters of the variable distances D1-D5 corresponding to the wide-angle end, intermediate end, and telephoto end of the zoom lens 100d are shown in Table 20 and Table 21 below. The effective focal lengths of each lens group G1c~G4c are shown in Table 21 below. Table 23 shows the relevant optical data of the zoom lens 100c of this embodiment, where the image height H can be half the length of the diagonal of the light valve LV. The total length of the lens mentioned in Table 23 can be the distance measured from the surface S1 of the lens L1 facing the magnification side MS to the surface S24 on the optical axis I at the wide-angle end.

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Table nineteen

Table twenty

Table 21

Table 22

Table 23

Table 25 below lists the aspheric coefficients and quadric surface coefficient values of each order of S1 and S2, and the aspheric surface equation can refer to formula (1). Table twenty-four

It can be seen from the above examples that the T/H ratio of each example is between 15 and 22, but when T/H≦25, T is the total length of the zoom lens, and H is the image height of the zoom lens; the total length is reduced Results can also be improved.

To sum up, in the zoom lens of the related embodiment of the present invention, the zoom function can be realized by three movable lens groups with fewer lens groups, and the manufacturing difficulty is relatively simple, and the manufacturing cost is relatively low. . At the same time, the zoom lens meets the condition of T/H≦25, so it can maintain the imaging quality with fewer lens groups.

It should be noted that the parameters listed in Table 1 to Table 24 are for illustrative purposes only and do not limit the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application. In addition, any embodiment or scope of claims of the present invention does not necessarily achieve all the objectives or advantages or features disclosed in the present invention. In addition, the abstract and the title are only used to assist the search of patent documents, and are not used to limit the scope of rights of the present invention.

1‧‧‧Projectors 100, 100a, 100b, 100c‧‧‧Zoom Lens TSP‧‧‧Transmissive Smooth Image Device D1~D5‧‧‧Variable Pitch G1, G1a, G1b, G1c‧‧‧First Lens group G2, G2a, G2b, G2c‧‧‧Second lens group G3, G3a, G3b, G3c‧‧‧Third lens group G4, G4a, G4b, G4c‧‧‧Fourth lens group I‧‧‧optical axis IB‧‧‧Illuminating Beam IMB‧‧‧Image Beam MS‧‧‧Enlargement Side L1~L15‧‧‧Lens LV‧‧‧Light Valve R‧‧‧Reflective Element RS‧‧‧Reducing Side S‧‧‧Aperture S1~ S30‧‧‧Surface OA‧‧‧Optics

FIG. 1A is a schematic diagram of a zoom lens according to a first embodiment of the present invention. FIG. 1B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the first embodiment of the present invention. FIG. 2A is a schematic diagram of a zoom lens according to a second embodiment of the present invention. 2B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the second embodiment of the present invention. FIG. 3A is a schematic diagram of a zoom lens according to a third embodiment of the present invention. 3B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the third embodiment of the present invention. FIG. 4A is a schematic diagram of a zoom lens according to a fourth embodiment of the present invention. 4B is a schematic diagram of the relative positions of the zoom lens at the wide-angle end, the middle end, and the telephoto end according to the fourth embodiment of the present invention.

1‧‧‧Projector

100‧‧‧zoom lens

TSP‧‧‧Transmissive smooth image device

D1~D4‧‧‧variable spacing

G1‧‧‧First lens group

G2‧‧‧Second lens group

G3‧‧‧The third lens group

G4‧‧‧The fourth lens group

I‧‧‧optical axis

IB‧‧‧Illumination Beam

IMB‧‧‧Image Beam

MS‧‧‧magnification side

L1~L13‧‧‧Lens

LV‧‧‧light valve

RS‧‧‧Reduction side

S‧‧‧aperture

S1~S29‧‧‧face

OA‧‧‧Optics Group

Claims (13)

A zoom lens, comprising: from the enlargement side to the reduction side, substantially only including four lens groups such as a first lens group, a second lens group, a third lens group and a fourth lens group, and the lens groups The diopters of each group are not equal to zero, and three of the lens groups are movable; the first lens group is movable, and the lens closest to the magnification side is an aspherical lens; when the zoom lens is When zooming, the three movable lens groups will all move; and the total lens length of the zoom lens is T, the image height of the zoom lens is H, and the zoom lens meets the condition of T/H≦25, wherein the zoom lens further includes An aperture, when the zoom lens zooms, the aperture is fixed relative to the image plane of the zoom lens. A zoom lens, comprising: from the enlargement side to the reduction side, substantially only including four lens groups such as a first lens group, a second lens group, a third lens group and a fourth lens group, and the lens groups The diopters of each group are not equal to zero, and three of the lens groups are movable; the first lens group is movable, and the lens closest to the magnification side is an aspherical lens; when the zoom lens is When zooming, the three movable lens groups will move; the zoom lens includes more than 12 lenses with diopters, Wherein the zoom lens further includes an aperture, and when the zoom lens zooms, the aperture is fixed relative to the image plane of the zoom lens. The zoom lens as described in items 1 and 2 of the scope of the patent application, wherein the aperture is arranged between the third lens group and the fourth lens group. The zoom lens as described in item 3 of the scope of the patent application, wherein when the zoom lens zooms, the aperture value of the aperture is a constant value. The zoom lens as described in item 3 of the scope of the patent application, wherein the aperture value of the aperture is less than or equal to 2. The zoom lens as described in item 5 of the scope of the patent application, wherein the zoom lens has less than or equal to 16 lenses with non-zero diopters. The zoom lens as described in item 1 or 2 of the scope of the patent application, wherein a reflective element is arranged on the optical path between the first lens group and the fourth lens group. The zoom lens as described in item 7 of the scope of the patent application, wherein the zoom lens includes less than three aspherical lenses. The zoom lens as described in item 7 of the scope of the patent application, wherein the reflective element is a reflective smooth image device (Reflective Smooth Picture, RSP). The zoom lens as described in item 7 of the scope of the patent application, wherein the reflective element is arranged on the optical path between the third lens group and the fourth lens group, and the reflective element is a reflective smooth image device (Reflective Smooth Picture, RSP). A zoom lens, comprising: from the enlargement side to the reduction side, substantially only including four lens groups such as a first lens group, a second lens group, a third lens group and a fourth lens group, and the lens groups The diopters of each group are not equal to zero, and three of the lens groups are movable; the first lens group is movable, and the lens closest to the magnification side is an aspherical lens; when the zoom lens is When zooming, the three movable lens groups will all move; the zoom lens includes 12 to 16 lenses with diopters; the third lens group and the fourth lens group include 6 or more lenses in total, wherein the zoom The lens further includes an aperture, and when the zoom lens zooms, the aperture is fixed relative to the image plane of the zoom lens. The zoom lens as described in item 11 of the scope of the patent application, wherein a reflective element is arranged on the optical path between the first lens group and the fourth lens group. The zoom lens as described in item 12 of the scope of the patent application, wherein the reflective element is arranged on the optical path between the third lens group and the fourth lens group, and the reflective element is a reflective smooth image device (Reflective Smooth Picture, RSP).

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