CN110554490A

CN110554490A - Zoom lens

Info

Publication number: CN110554490A
Application number: CN201910467107.XA
Authority: CN
Inventors: 陈凯筠; 王国权
Original assignee: Young Optics Inc
Current assignee: Young Optics Inc
Priority date: 2018-05-31
Filing date: 2019-05-31
Publication date: 2019-12-10
Also published as: TWI805585B; TW202004255A

Abstract

A zoom lens substantially includes only first to fourth lens groups from an enlargement side to a reduction side. The first lens group is movable. Three movable lens groups when the zoom lens zooms. The total lens length of the zoom lens is T, and the image height of the zoom lens is H. The zoom lens meets the condition that T/H ≦ 25. Another zoom lens is also provided.

Description

Zoom lens

Technical Field

The present disclosure relates to zoom lenses, and particularly to a zoom lens.

Background

In a typical zoom lens, a plurality of lenses disposed in the lens are grouped, and the lens groups (for example, five or more lens groups) are moved correspondingly according to the requirements of zooming or focusing. However, the above-mentioned multi-lens design increases the difficulty and cost of lens manufacture and makes the lens size unable to be reduced. Therefore, how to manufacture a zoom lens with low cost, small size and good imaging quality is one of the important issues of those skilled in the art.

Disclosure of Invention

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

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

In an embodiment of the present invention, a zoom lens is provided, which is applied in a projector, from an output side (or an enlargement side, or a side close to a projection screen) of light to an input side (a reduction side, close to an image plane) of light, the zoom lens is sequentially grouped according to the mobility of the lens, and four lens groups are arranged, which are sequentially referred to as a first lens group, a second lens group, a third lens group and a fourth lens group. The lens closest to the magnification side in the first lens group is an aspherical lens. When the zoom lens zooms, at least three movable lens groups are included in the four lens groups. For example, in this embodiment, during zooming, the first, second and third lens groups move relative to the image plane, and the fourth lens group is fixed relative to the image plane. Further, the total lens length of the zoom lens divided by the image height of the zoom lens is 25 or less. Through the design of the embodiment of the invention, the zoom lens can realize the zooming function under fewer lens groups and at least three movable lens groups, the manufacturing difficulty is simpler, the manufacturing cost is lower, and the size of the zoom lens can be reduced when the ratio of the total length divided by the image height is 25 or below.

In an embodiment of the present invention, a zoom lens is provided, which is applied in a projector, from an output side (or an enlargement side, or a side close to a projection screen) of light to an input side (a reduction side) of the light, the four lens groups are grouped according to the mobility of the lenses, and are sequentially referred to as a first lens group, a second lens group, a third lens group, and a fourth lens group. The lens closest to the magnification side in the first lens group is an aspherical lens and has a negative refractive power. The lens closest to the magnification side in the first lens group is an aspherical lens. When the zoom lens zooms, at least three movable lens groups are included in the four lens groups. For example, in this embodiment, during zooming, the first, second and third lens groups move relative to the image plane, and the fourth lens group is fixed relative to the image plane. In addition, the zoom lens includes 12 or more lenses with non-zero diopter.

in an embodiment of the present invention, a zoom lens is provided, which is applied in a projector, from an output side (or an enlargement side, or a side close to a projection screen) of light to an input side (a reduction side) of the light, the four lens groups are grouped according to the mobility of the lenses, and are sequentially referred to as a first lens group, a second lens group, a third lens group, and a fourth lens group. Each group of the four lens groups has diopter not equal to zero, and three of the lens groups are movable; the first lens group is movable, and a lens closest to the magnification side thereof is an aspherical lens. When the zoom lens zooms, all the three movable lens groups move. The number of lenses with diopter in the zoom lens is between 12 to 16. The third lens group and the fourth lens group include 6 or more lenses in total.

Through the design of the embodiment of the invention, the zoom lens can realize the zooming function under fewer lens groups and through at least three movable lens groups, the manufacturing difficulty is simpler, the manufacturing cost is lower, and the zoom lens of the embodiment comprises more than 12 lenses with diopter.

in order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1A is a schematic view of a zoom lens according to a first embodiment of the present invention.

Fig. 1B is a schematic view of the zoom lens according to the first embodiment of the present invention at the relative positions of the wide-angle end, the middle end, and the telephoto end.

Fig. 2A is a schematic view of a zoom lens according to a second embodiment of the present invention.

Fig. 2B is a schematic view of the zoom lens according to the second embodiment of the present invention at the relative positions of the wide-angle end, the middle end, and the telephoto end.

FIG. 3A is a schematic view of a zoom lens according to a third embodiment of the present invention.

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

FIG. 4A is a schematic view of a zoom lens according to a fourth embodiment of the present invention.

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

Description of the main Components

1	Projector with a light source
		100、100a、100b、100c	Zoom lens
TSP	Penetration type image smoothing 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 light beam
IMB	Image light beam
		MS	Side of enlargement
L1-L15	Lens and lens assembly
		LV	Light valve
R	Reflective element
		RS	Reduction side
S	Aperture
		S1-S30	Noodle
OA	Optical prism group

Detailed Description

The foregoing and other technical and scientific aspects, features and utilities of the present invention will be apparent from the following detailed description of the embodiments, which is to be read in connection with the accompanying drawings. Directional terms as referred to in the following examples, for example: "upper," "lower," "left," "right," "front" or "rear," etc., refer only to the orientation of the figures. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting.

Through the design of the embodiment of the invention, the zoom lens which has simple design and can provide better imaging quality can be provided.

FIG. 1A is a schematic view of a zoom lens according to a first embodiment of the present invention; fig. 1B is a schematic view of the zoom lens of the first embodiment of the present invention at the relative positions of the WIDE angle end (WIDE), the middle end (MID), and the telephoto end (TELE).

The zoom lens 100 may be, for example, an optical system, such as an image capturing device of a projector 1 or a camera. In this example, the optical system is a projector 1 employing a zoom lens 100 of a Telecentric (Telecentric) configuration.

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

The illumination system IS, the light valve LV, the optical prism group OA and the transmission type smooth image device TSP are arranged between the reduction side RS and the lens. The illumination system 10 is configured to provide an illumination beam IB to the light valve LV.

the light valve LV may be any one of spatial light modulators such as a Digital Micromirror Device (DMD), a Liquid Crystal On Silicon (LCOS) or a transmissive liquid crystal panel (LCD). The optical prism group OA is disposed on the transmission path IB of the illumination beam IB. The illumination beam IB is totally reflected by the optical prism group OA and then enters the light valve LV. When the light valve LV is a DMD, a plurality of micromirrors on its surface are located on the image plane of the lens, and the illumination beam IB is converted into the image beam IMB. The image beam IMB sequentially passes through the optical prism group OA, enters the zoom lens 100 through the transparent smooth image device TSP, and forms an image at the focal point of the magnification side MS through the zoom lens 100.

The transmission type smooth image device TSP is a widely used optical element including a swingable plate glass, and is used to improve resolution.

as mentioned above, the zoom lens 100 can be used for image capture, and the photosensitive element (not shown) can be disposed 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 is, 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.

Referring to fig. 1A and 1B, in the present example, the zoom lens 100 has an optical axis I, and includes, in order along the optical axis I from a magnification side MS to a reduction side RS, a first lens group G1, a second lens group G2, a stop S, a third lens group G3, and a fourth lens group G4. The lens groups G1-G4 each include at least one or more lenses with Refractive Power. If the lens group has a plurality of lenses, the lenses move together when the lens group moves, and the distance between any two adjacent lenses in the lens group does not change with the focal length adjustment of the zoom lens 100. That is, the lens groups are grouped by their mobility. In this example, the zoom lens 100 includes 3 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 each move on the optical axis I with respect to an active surface or an image plane (the same applies hereinafter) on the light valve LV, so as to switch between a wide-angle end, a middle end, and a telephoto end to perform a zooming operation (Zoom). In Focusing (FOCUS), the first lens group G1 is moved to FOCUS, and the fourth lens group G4 remains stationary with respect to the active surface of the light valve LV during both zooming and focusing.

Referring 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 along the optical axis I to the diminished side RS, the magnified side MS, and the magnified side MS, respectively, while the fourth lens group G4 and the stop S are fixed relative to the operating surface of the light valve LV. At this time, the variable pitches D1, D2, D3 and D4 of the zoom lens 100 become smaller, larger, smaller and larger, respectively.

Referring 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 along the optical axis I to the reduction side RS, the enlargement side MS, and the third lens group G4 and the stop S are fixed relative to the light valve LV. At this time, the variable pitches D1, D2, D3, and D4 of the zoom lens 100 become smaller and larger, respectively.

Further, in the above-described zooming process, the aperture value of the aperture S is a constant value.

In this example, the lenses having diopter in the zoom lens 100 are 13 pieces, wherein the aspheric lens is 2 pieces, and the spherical lens is 11 pieces. The lens arrangement, refractive power, material and lens type of each lens group G1-G4 in zoom lens 100 will be described in detail in the following paragraphs.

The first lens group G1 has negative refractive power, and includes lenses L1, L2, L3, L4 and L5 in this order along the optical axis I from the magnification side MS to the reduction side RS, the refractive powers being negative, positive, respectively. The Lens L1 is a Lens having refractive power closest to the magnification side MS in the first Lens group G1, and its material is plastic, and it is an Aspherical Lens (aspheric Lens). The lenses L2-L5 are all Spherical lenses (Spherical lenses), and the materials of the lenses L2-L5 are all glass. The lenses L2, L3 are double cemented lenses (centered doublets).

The second lens group G2 has positive refractive power and includes a lens L6, the refractive power of which is positive for lens L6. The lens L6 is a spherical lens, and its material is glass.

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

The third lens group G3 has positive refractive power, and includes lenses L7, L8, L9, L10, L11, L12 in this order along the optical axis I from the magnification side MS to the reduction side RS, and its refractive powers are negative, positive, negative, positive, and positive, respectively. The lenses L7-L12 are all spherical lenses, and the lenses L7-L12 are all made of glass. Lenses L7, L8, L9 are cemented triplets. The lenses L10 and L11 are doublets.

The fourth lens group G4 is positive in diopter and includes lens L13, and lens L13 is positive in diopter. Lens L13 is an aspherical lens and is made of glass and is manufactured by a hot press molding process.

It should be noted that in the present embodiment, two adjacent surfaces of two adjacent lenses in the doublet or cemented lens have the same or similar curvature radius, and the two adjacent surfaces of the doublet or cemented lens can be attached by different methods, such as, but not limited to, coating optical glue between the two adjacent surfaces for cementing, and pressing the two adjacent surfaces by a mechanical member.

in the zoom lens 100, each lens has an enlargement side convex, concave, or flat surface facing the enlargement side MS and passing the imaging light and a reduction side convex, concave, or flat surface facing the reduction side RS and passing the imaging light. The shapes of the surfaces corresponding to the above-mentioned elements will be described in detail in the following paragraphs.

In the first lens group G1, the lens L1 has a convex enlarged-side surface S1 and a concave reduced-side surface S2. The lens L2 has an enlarged concave side S3 and a reduced concave side (not shown). The lens L3 has an enlargement-side convex surface S4 and a reduction-side convex surface S5. The lens L4 has an enlarged-side concave surface S6 and a reduced-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 magnified side convex surface S10 and a reduced side plane S11.

S12 is a diaphragm S. In this example, the aperture S is a fixed aperture, typically a machine or structural member having a light-transmissive aperture of fixed size in the middle; however, if desired, a replacement by an adjustable diaphragm of the IRIS, for example, is also possible.

In the third lens group G3, the lens L7 has a convex enlarged-side surface S13 and a concave reduced-side surface (not shown). The lens L8 has an enlarged-side convex surface S14 and a reduced-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 enlarged concave side S17 and a reduced concave side (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 a magnification-side convex surface S22 and a reduction-side convex surface S23.

The transmission-type smooth image device TSP has an enlargement side surface S24 and a reduction side surface S25. The optical prism group OA has an enlarged side surface S26 and a reduced 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 optical prism group OA, and the design parameters of the light valve LV are shown in table one below. Design parameters and related optical parameters of the zoom lens 100 at the variable pitches D1-D4 at the wide angle end, the middle end, and the telephoto end are shown in the following tables two and three. The Effective Focal Length (EFL) of each lens group G1-G4 is shown in Table four below. Table V shows the optical data associated with the zoom lens 100 of the present embodiment, wherein the image height H can be half the length of the diagonal of the actuating surface of the light valve LV. The total lens length t (ttl) mentioned in table five refers to the maximum distance along the optical axis of two lenses with diopter that are farthest from each other along the optical axis in the zoom lens when the lens is at the wide-angle end. In this example, the total lens length is, for example, a distance measured on the optical axis I and at the wide-angle end from the surface S1 to the surface S23 of the lens L1 toward the magnification side MS. However, the invention is not limited to the details given herein, and those skilled in the art can make appropriate changes in the parameters and settings described herein, while remaining within the scope of the invention. The legend in the surface column represents an aspherical surface; if not, the spherical surface is obtained.

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Watch III

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Furthermore, in each of the following design examples of the present invention, the aspheric polynomial may be expressed by the following formula:

In the above formula (1), x is the offset (sag) in the direction of the optical axis I, c' is the reciprocal of the radius of the Osculating Sphere (Osculating Sphere), that is, the reciprocal of the radius of curvature near the optical axis I, k is the conic coefficient, and y is the aspheric height, that is, the height from the center of the lens to the edge of the lens. A to E represent aspheric coefficients of respective orders of the aspheric polynomial, respectively. The sixth table below lists the aspheric coefficients and conic coefficient values of each order for S1, S2, S22, S23.

Watch six

Noodle

k

A

B

C

D

E

S1

-0.02028

-7.46E-05

2.14E-07

-5.09E-10

7.41E-13

-5.70E-16

S2

-1.1332

-6.24E-05

3.46E-07

-8.85E-10

1.77E-12

0

S22

0

-9.77E-06

5.34E-09

7.67E-11

7.47E-13

0

S23

0

-7.86E-06

1.00E-08

7.50E-11

8.50E-13

0

It should be noted that, the following embodiments follow the contents of the foregoing embodiments, descriptions of the same technical contents are omitted, reference may be made to the contents of the foregoing embodiments for the same element names, and repeated descriptions of the following embodiments are omitted.

Fig. 2A is a schematic view of a zoom lens according to a second embodiment of the present invention. Fig. 2B is a schematic view of the zoom lens according to the second embodiment of the present invention at the relative positions of the wide-angle end, the middle end, and the telephoto end. For clarity of illustration of the action relationship between the lens groups, fig. 2B shows the zoom lens in a horizontal manner, and the zoom lens shown in the horizontal manner is optically equivalent to the L-shape zoom lens in fig. 2A, and so on.

Referring to fig. 2A, in the present embodiment, the zoom lens 100a is substantially similar to the zoom lens 100, and the main differences are: the zoom lens 100a includes, in order along the optical axis I from the magnification side MS to the reduction side RS, a first lens group G1a, a second lens group G2a, a third lens group G3a, a stop S, and a fourth lens group G4 a. In addition, a Reflective element R is disposed on the optical path between the lens L7 and the diaphragm S, and in the present embodiment, the Reflective element R is a Reflective Smooth image device (RSP), but it may be replaced by a mirror or other elements having a light guiding function. Furthermore, the reflecting element R may be omitted so that the light path does not need to be turned, and the invention is not limited thereto. The zoom lens 100a may be turned into an L-shape. In this example, when the zoom lens 100a zooms, the first lens group G1a, the second lens group G2a, the third lens group G3a, and the fourth lens group G4a each move on the optical axis I so as to switch between the wide angle end, the middle end, and the telephoto end for zooming operation, and the fourth lens group G4a moves on the optical axis I when focusing is performed.

referring 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 move along the optical axis I to the diminished side RS, the magnified side MS, and the fourth lens group G4a moves along the optical axis I to the magnified side MS for focusing, and the stop S is fixed relative to the active surface of the light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become small, large, small, and large, respectively.

Referring 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 move along the optical axis I to the reduction side RS, the enlargement side MS, and the fourth lens group G4a moves along the optical axis I to the reduction side MS for focusing operation, and the diaphragm S is fixed relative to the operating surface of the light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become small, large, small, and large, respectively.

In this example, the lenses having diopter in the zoom lens 100a are 12 pieces, wherein the aspheric lens is 1 piece, and the spherical lens is 11 pieces. The lens arrangement, refractive power, material and lens type of each lens group G1a-G4a in zoom lens 100a will be described in detail in the following paragraphs.

The first lens group G1a has negative refractive power and includes lenses L1, L2, L3 along the optical axis I from the magnification side MS to the reduction side RS, and the refractive powers of these lenses L1, L2, and L3 are negative, and positive, respectively. The material of the lens L1 is plastic, and is an aspherical lens. The lenses L2 and L3 are doublets. The lenses L2 and L3 are both made of glass and are spherical lenses.

The second lens group G2a has negative refractive power, and includes lenses L4, L5 in order along the optical axis I from the magnification side MS to the reduction side RS, and the refractive powers of the lenses L4, L5 are negative and positive, respectively. The lenses L4 and L5 are doublets. The lenses L4 and L5 are both made of glass and are spherical lenses.

The third lens group G3a has positive refractive power and includes a lens L6, the refractive power of which is positive for lens L6. The material of the lens L6 is glass, and is a spherical lens.

The stop S is disposed between the third lens group G3a and the fourth lens group G4 a.

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 negative, positive, negative, positive, respectively. Lenses L7, L8, L9 are cemented triplets. The lenses L10 and L11 are doublets. The lenses L7-L12 were all glass and were all spherical lenses.

The lens shapes of the lens groups G1a-G4a can be found in the following table and the drawings, and are not described herein again.

The lens design parameters of the zoom lens 100a and the design parameters of the optical prism group OA and the light valve LV are shown in the following table seven. Design parameters and related optical parameters of the variable pitches D1-D5 of the zoom lens 100a at the wide angle end, the middle end, and the telephoto end are shown in the following tables eight and nine. The effective focal lengths of the lens groups G1a-G4a are shown in Table ten below. Table eleven is the relevant optical data of the zoom lens 100a of the present embodiment, where the image height H may be half the length of the diagonal of the light valve LV. The total lens length mentioned in table eleven may be a distance on the optical axis I measured at the wide-angle end from the surface S1 to the surface S20 of the lens L1 toward the magnification side MS.

watch seven

Table eight

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The second two tables below show the aspheric coefficients and conic coefficient values of the respective orders S1 and S2, and the aspheric equation can be referred to as equation (1).

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Noodle

k

A

B

C

D

E

S1

-0.5164943

-7.52E-05

1.82E-07

-3.65E-10

4.16E-13

-2.34E-16

S2

-0.98379322

-7.62E-05

2.91E-07

-5.40E-10

6.30E-13

0

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

Referring to fig. 3A and 3B, the zoom lens 100B includes, in order along an optical axis I from a magnification side MS to a reduction side RS, a first lens group G1B, a second lens group G2B, a third lens group G3B, a stop S, and a fourth lens group G4B. In this example, when the zoom lens 100b is zoomed, the first lens group G1b, the second lens group G2b, and the third lens group G3b each move on the optical axis I so as to be switched among the wide angle end, the middle end, and the telephoto end for a zooming operation, and the fourth lens group G4b moves on the optical axis I for a focusing operation.

Referring to fig. 3B, when the zoom lens 100B is switched from the wide-angle end to the middle end, the first lens group G1B, the second lens group G2B, and the third lens group G3B respectively move along the optical axis I toward the reduction side RS, the enlargement side MS, and the enlargement side MS with respect to the operating surface (the same applies below) on the light valve LV for zooming, while the fourth lens group G4a moves along the optical axis I toward the enlargement side MS for focusing, and the stop S is fixed with respect to the operating surface on the light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become small, large, small, and large, respectively.

Referring 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 respectively move along the optical axis I to the reduction side RS, the enlargement side MS, and the enlargement side MS for zooming, while the fourth lens group G4B moves along the optical axis I to the enlargement side MS for focusing, and the diaphragm S is fixed relative to the operating surface of the light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become smaller, larger, smaller, and larger, respectively.

in this example, the lenses having diopter in the zoom lens 100b are 14 pieces, of which aspheric lens is 1 piece and spherical lens is 13 pieces. The lens arrangement, refractive power, material and lens type of each lens group G1a-G4a in zoom lens 100a will be described in detail in the following paragraphs.

The first lens group G1b has negative refractive power and includes lenses L1, L2, L3, L4 in order along the optical axis I from the magnification side MS to the reduction side RS, and the refractive powers of these lenses L1, L2, L3, and L4 are negative, positive, respectively. The material of the lens L1 is plastic, and is an aspherical lens. The lenses L3 and L4 are doublets. The lenses L2, L3, and L4 are all made of glass and are all spherical lenses.

The second lens group G2b has negative refractive power, and includes lenses L5, L6 in order along the optical axis I from the magnification side MS to the reduction side RS, and the refractive powers of the lenses L5, L6 are negative and positive, respectively. The lenses L5 and L6 are doublets. The lenses L5 and L6 are both made of glass and are spherical lenses.

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

The stop S is disposed between the third lens group G3b and the fourth lens group G4 b.

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 negative, positive, negative, positive, respectively. Lenses L9, L10, L11 are cemented triplets. The lenses L12 and L13 are doublets. The lenses L9-L14 were all glass and were all spherical lenses.

The lens shapes of the lens groups G1b-G4b can be found in the following table and the drawings, and are not described herein again.

The lens design parameters of the zoom lens 100b and the design parameters of the optical prism group OA and the light valve LV are shown in the following thirteen table. The design parameters and the related optical parameters of the variable pitches D1-D5 of the zoom lens 100b at the wide angle end, the middle end, and the telephoto end, respectively, are shown in the following tables fourteen and fifteen. The effective focal lengths of the lens groups G1b-G4b are shown in Table sixteen below. Table seventeenth is the relevant optical data of the zoom lens 100b of the present embodiment, wherein the image height H may be half the length of the diagonal of the light valve LV. Wherein the total lens length mentioned in table seventeen is a distance on the optical axis I measured at the wide-angle end from the surface S1 of the lens L1 toward the magnification side MS to the surface S24 of the light valve LV.

Watch thirteen

Table fourteen

Fifteen items of table

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Seventeen table

The following table eighteen shows the aspheric coefficients and conic coefficient values of the orders S1 and S2, and the aspheric equation can refer to equation (1).

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

Referring to fig. 4A and 4B, the zoom lens 100c includes, in order along an optical axis I from a magnification side MS to a reduction side RS, a first lens group G1c, a second lens group G2c, a third lens group G3c, a stop S, and a fourth lens group G4 c. In this example, when the zoom lens 100c is zoomed, the first lens group G1c, the second lens group G2c, and the third lens group G3c each move on the optical axis I so as to be switched among the wide angle end, the middle end, and the telephoto end for a zooming operation, and the fourth lens group G4c moves on the optical axis I for a focusing operation.

Referring 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 along the optical axis I to the diminished side RS, and magnified side MS, respectively, for zooming, and the fourth lens group G4c moves along the optical axis I to the diminished side RS for focusing, the stop S is fixed relative to the operating surface of the LV valve. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become small, large, small, and large, respectively.

Referring to FIG. 4B, when the zoom lens 100c is switched from the middle to the wide-angle end, the first lens group G1c, the second lens group G2c, and the third lens group G3c move along the optical axis I to the diminished side RS, the magnified side MS, and the magnified side MS, respectively, for zooming, and the fourth lens group G4c moves along the optical axis I to the magnified side MS for focusing, the stop S is fixed relative to the active surface of the light valve LV. At this time, the variable pitches D1, D2, D3, D4, and D5 of the zoom lens become small, large, small, and large, respectively.

In this example, the lenses having diopter in the zoom lens 100c are 15 pieces, wherein the aspheric lens is 1 piece, and the spherical lens is 14 pieces. The lens arrangement, refractive power, material and lens type of each lens group G1c-G4c in zoom lens 100c will be described in detail in the following paragraphs.

The diopter of the first lens group G1c is negative, and includes lenses L1, L2, L3, L4 in order 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 negative, positive, respectively. The material of the lens L1 is plastic, and is an aspherical lens. The lenses L2-L4 were all glass and were all spherical lenses.

The second lens group G2c has negative refractive power and includes lenses L5 and L6 along the optical axis I in order from the magnification side MS to the reduction side RS, and the refractive powers of the lenses L5 and L6 are negative and positive, respectively. The lenses L5 and L6 are doublets. The lenses L5 and L6 are both made of glass and are spherical lenses.

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

The stop S is disposed between the third lens group G3c and the fourth lens group G4 c.

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 negative, positive, negative, positive, respectively. Lenses L10, L11, L12 are cemented triplets. The lenses L13 and L14 are doublets. The lenses L9-L15 were all glass and were all spherical lenses.

The lens shapes of the lens groups G1d to G4d can be found in the following table and the drawings, and will not be described herein.

The lens design parameters of the zoom lens 100d and the design parameters of the optical prism group OA and the light valve LV are shown in the following table nineteenth. Design parameters and related optical parameters of the zoom lens 100D at the variable pitches D1-D5 at the wide angle end, the middle end, and the telephoto end, respectively, are shown in the following tables twenty and twenty-one. The effective focal lengths of the lens groups G1c-G4c are shown in Table twenty-two below. Table twenty-three is the relevant optical data of the zoom lens 100c of the present embodiment, wherein the image height H may be half the length of the diagonal of the light valve LV. Wherein the total lens length mentioned in the twenty-third table may be a distance on the optical axis I measured at the wide-angle end from the surface S1 toward the magnification side MS to the surface S24 of the lens L1.

Table nineteen

Watch twenty

TABLE twenty one

Watch twenty two

Watch twenty three

The following twenty-four tables show the aspheric coefficients and conic coefficient values of the orders S1 and S2, and the aspheric equation can refer to the equation (1).

Watch twenty four

According to the previous examples, the T/H ratio of each example is between 15 and 22, but when T/H ≦ 25, T is the total lens length of the zoom lens, and H is the image height of the zoom lens; the overall length reduction results can also be improved.

In summary, in the zoom lens according to the related embodiment of the invention, the zoom function can be realized with fewer lens groups and with three movable lens groups, and the manufacturing difficulty is simple and the manufacturing cost is low. Meanwhile, the zoom lens meets the condition that T/H is less than or equal to 25, so that the imaging quality can be simultaneously maintained with fewer lens groups.

It should be noted that the parameters listed in tables one through twenty-four are for illustrative purposes only and are not intended to limit the present invention. Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. Moreover, not all objects, advantages, or features of the disclosure are necessarily to be achieved in any one embodiment or the scope of the claims. In addition, the abstract and the title of the invention are provided for assisting the search of patent documents and are not intended to limit the scope of the invention.

Claims

1. A zoom lens, comprising:

From the zooming side to the zooming side, the zoom lens substantially only comprises four lens groups, namely a first lens group, a second lens group, a third lens group and a fourth lens group, wherein the diopter of each group of the four lens groups is not equal to zero, and three lens groups are movable;

The first lens group is movable, and one lens of the first lens group, which is closest to the magnification side, is an aspheric lens;

When the zoom lens zooms, the three movable lens groups 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 that T/H is less than or equal to 25.

2. A zoom lens, comprising:

From the zooming side to the zooming side, the zoom lens substantially only comprises four lens groups, namely a first lens group, a second lens group, a third lens group and a fourth lens group, wherein the diopter of each group of the four lens groups is not equal to zero, and three lens groups are movable; the first lens group is movable, and one lens of the first lens group, which is closest to the magnification side, is an aspheric lens;

When the zoom lens zooms, the three movable lens groups move;

The zoom lens comprises more than 12 lenses with diopter.

3. A zoom lens, comprising:

When the zoom lens zooms, the three movable lens groups move;

The number of lenses with diopter in the zoom lens is between 12 to 16;

The third lens group and the fourth lens group include 6 or more lenses in total.

4. A zoom lens according to claim 1, 2 or 3, further comprising an aperture, said aperture being fixed with respect to an image plane of said zoom lens upon zooming of said zoom lens.

5. The zoom lens according to claim 4, wherein the aperture is provided between the third lens group and the fourth lens group.

6. The zoom lens according to claim 5, wherein an aperture value of the aperture is a constant value when the zoom lens is zoomed.

7. The zoom lens according to claim 5, wherein an aperture value of the aperture is 2 or less.

8. The zoom lens according to claim 7, wherein the number of lenses having a diopter other than zero in the zoom lens is 16 or less.

9. A zoom lens according to claim 1, 2 or 3, wherein a reflecting element is provided on an optical path between the first lens group and the fourth lens group.

10. The zoom lens of claim 9, wherein the reflective element is a reflective smooth image device.

11. The zoom lens of claim 9, wherein the reflective element is located on an optical path of the third and fourth lens cells.

12. The zoom lens according to claim 9, wherein the number of aspherical lenses in the zoom lens is equal to or less than 3.