CN115220182B

CN115220182B - Projection lens and projector

Info

Publication number: CN115220182B
Application number: CN202210715913.6A
Authority: CN
Inventors: 肖顺东
Original assignee: Foshan Quying Technology Co ltd
Current assignee: Foshan Quying Technology Co ltd
Priority date: 2022-06-23
Filing date: 2022-06-23
Publication date: 2023-10-20
Anticipated expiration: 2042-06-23
Also published as: CN115220182A

Abstract

The application discloses a projection lens and a projector, which sequentially comprise from an object side to an image side: a first lens group with positive focal power, a diaphragm and a second lens group with positive focal power. The first lens group sequentially comprises two negative focal power lenses, a negative focal power cemented lens and a positive focal power lens from the object side to the image side. The second lens group sequentially comprises a group of negative focal power cemented lenses and two positive focal power lenses from the object side to the image side. The projection lens has the advantages of small lens number, simple structure and easy manufacture, and the cost of the projection lens is reduced. The number of lenses of the whole lens is small, so that the transmittance of the whole lens is high, and the aperture is large, thereby achieving the purpose of high projection brightness.

Description

Projection lens and projector

Technical Field

The present application relates to the field of image display technologies, and in particular, to a projection lens and a projector.

Background

The projector is used as necessary projection equipment in various places in life such as teaching and cinema, the projection lens is the last link in the light path of the projector, and is also an extremely important link, and the design of the projection lens not only influences the performance of the projector, but also determines the quality of the projection effect.

At present, a common digital projection display technology mainly adopts a DMD (Digital Micromirror Device ) or LCOS (Liquid Crystal On Silicon, liquid crystal on silicon) as a display device, adopts a polarization beam splitting element or a total reflection beam splitting element as an illumination or imaging beam splitting device, and gathers images reflected on the display device on a projection screen through a reasonably designed projection lens light path.

The investigation shows that the projection image quality of the 0.47' telecentric projection lens on the market at present is poor. And because more lenses or more plastic lenses are used, the transmittance of the whole lens is lower, and the brightness of the final projection is lower. The present application has been made to solve the above-described problems.

Disclosure of Invention

The present application is directed to a projection lens and a projector, which solve one or more of the technical problems of the prior art, and at least provide a beneficial choice or creation condition.

The technical scheme adopted for solving the technical problems is as follows:

the application provides a projection lens, which sequentially comprises a first lens group with positive focal power, a diaphragm and a second lens group with positive focal power from an object side to an image side;

the first lens group sequentially comprises two negative focal power lenses, a group of negative focal power cemented lenses and a positive focal power lens from the object side to the image side;

the second lens group sequentially comprises a group of negative focal power cemented lenses and two positive focal power lenses from the object side to the image side;

and satisfies the following conditional expression:

4<|f1/f2︱<7

TTL/EFFL<10

TTL/BFL<4.5

wherein, the liquid crystal display device comprises a liquid crystal display device,

f1: the focal length of the first lens group,

f2: the focal length of the second lens group,

TTL is the distance between the first surface of the first lens sheet of the lens and the imaging surface,

EFFL: the focal length of the lens is set,

BFL: the distance between the second surface of the last lens of the second lens group of the lens and the image surface of the DMD.

The beneficial effects of the application are as follows:

the projection lens has the advantages of small lens number, simple structure and easy manufacture, and the cost of the projection lens is reduced. The number of lenses of the whole lens is small, so that the transmittance of the whole lens is high, and the aperture is large, thereby achieving the purpose of high projection brightness. .

As a further improvement of the above technical solution, the projection lens has only two groups.

As a further improvement of the above technical solution, a diaphragm is arranged between the first lens group and the second lens group, and the position of the diaphragm is fixed.

As a further improvement of the above technical solution, in the first lens group, the first lens is a meniscus lens, where both the first surface and the second surface are curved toward the image side; the second lens is a meniscus lens, wherein the first surface and the second surface are both bent towards the image space, and at least one surface is an aspheric surface; the third lens and the fourth lens are combined into a cemented lens, wherein the first surface of the third lens is bent towards the object, the second surface of the fourth lens is bent towards the object, and the cemented lens of the combined lens is bent towards the object or towards the image; the fifth lens is a biconvex positive lens.

As a further improvement of the above technical solution, the first lens group satisfies the following conditional expression:

Vd11>50

Vd12>50

Vd13<24

Vd15<24

vd11: the first lens group has a first sheet lens abbe number,

vd12: the second lens element of the first lens group has a dispersion coefficient,

vd13: the third lens element of the first lens group has a dispersion coefficient,

vd15: the first lens group fifth lens element has a dispersion coefficient.

As a further improvement of the above technical solution, the first lens and the second lens in the second lens group are combined into a cemented lens, wherein a first face of the cemented lens is curved toward the object side or toward the image side, a second face of the cemented lens is curved toward the object side, and a third face of the cemented lens is curved toward the object side or toward the image side; the third lens is a biconvex positive lens; the fourth lens is a positive lens, wherein the first surface is bent towards the object side or towards the image side, the second surface is bent towards the object side, and at least one surface is an aspheric surface.

As a further improvement of the above technical solution, the second lens group of the projection lens satisfies the following conditional expression:

Vd21>64

Vd23>64

Vd24>50

f23/f2>1.0

vd21: the abbe number of the first lens of the second lens group,

vd23: the abbe number of the third lens of the second lens group,

vd24: the abbe number of the fourth lens of the second lens group,

f23: focal length of the third lens of the second lens group,

f2: focal length of the second lens group.

The application also provides a projector, which comprises the projection lens.

Drawings

The application is further described below with reference to the drawings and examples;

fig. 1 is a view showing a configuration of a projection lens according to an embodiment of the present application.

Fig. 2 shows an MTF curve of a projection lens according to an embodiment of the present application.

Fig. 3 shows a distortion diagram of a projection lens according to an embodiment of the present application.

Fig. 4 shows a color difference diagram of a projection lens according to an embodiment of the present application.

Fig. 5 shows a configuration diagram of a projection lens according to a second embodiment of the present application.

Fig. 6 shows an MTF curve of a projection lens according to a second embodiment of the present application.

Fig. 7 shows a distortion chart of a projection lens according to a second embodiment of the present application.

Fig. 8 shows a color difference diagram of a projection lens according to a second embodiment of the present application.

Fig. 9 shows a configuration diagram of a projection lens according to a third embodiment of the present application.

Fig. 10 shows a projection lens MTF curve according to a third embodiment of the present application.

Fig. 11 shows a distortion chart of a projection lens according to a third embodiment of the present application.

Fig. 12 shows a color difference chart of a projection lens according to a third embodiment of the present application.

Reference numerals: 10 denotes a first lens group; 20 denotes a second lens group; 30 denotes an aperture; 40 denotes an oscillating piece; 50 denotes a prism in the illumination system; 60 denotes DMD protection glass; 70 denotes an image plane; 100 denotes the entire projection lens system structure.

Detailed Description

Reference will now be made in detail to the present embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present application, but not to limit the scope of the present application.

In the description of the present application, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present application and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

In the description of the present application, if there is a word description such as "a plurality" or the like, the meaning of a plurality is one or more, and the meaning of a plurality is two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number.

In the description of the present application, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present application can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

Referring to fig. 1 to 12, a projection lens 100 and a projector according to the present application make the following embodiments:

fig. 1 is a view of a projection lens 100 according to a first embodiment of the present application. The projection lens 100 includes, in order from an object side to an image side: a first lens group 10 having positive optical power, a second lens group 20, 30 having positive optical power, represent apertures; 40 denotes an oscillating piece; 50 denotes a prism in the illumination system; 60 denotes DMD protection glass; 70 denotes an image plane; 100 denotes the entire projection lens system structure.

And is configured to satisfy the following conditional expressions (1), (2) and (3):

4<|f1/f2︱<7---------------(1)

TTL/EFFL<10---------------(2)

TTL/BFL<4.5---------------(3)

f1: the focal length of the first lens group 10,

f2: the focal length of the second lens group 20,

EFFL: the focal length of the lens is set,

BFL: the distance from the second surface of the last lens of the second lens group 20 to the image surface of the DMD.

In this embodiment, the second lens group 20 includes, in order from the object side to the image side: the first lens and the second lens group 20 compose a cemented lens, wherein a first face of the cemented lens is a plane, a second face of the cemented lens is curved toward the object side, and a third face of the cemented lens is curved toward the image side; the third lens is a biconvex positive lens; the fourth lens is a positive lens, wherein the first surface is bent towards the object, the second surface is bent towards the object, and both surfaces are aspheric.

The second lens group 20 of the projection lens 100 is configured to satisfy the following conditional expressions (8), (9), (10), (11):

Vd21>64--------------(8)

Vd23>64--------------(9)

Vd24>50--------------(10)

f23/f2>1.0--------------(11)

vd21: the abbe number of the first lens of the second lens group 20,

vd23: the abbe number of the third lens element of the second lens group 20,

vd24: the abbe number of the fourth lens element of the second lens group 20,

f23: focal length of the third lens element of the second lens group 20,

f2: focal length of the second lens group 20.

The present application discloses a projection lens 100, which sequentially comprises from an object side to an image side: a first lens group 10 having positive optical power, a stop, a second lens group 20 having positive optical power. The first lens group 10 is composed of two lenses with negative focal power, a cemented lens with negative focal power and a lens with positive focal power in sequence from the object side to the image side. The second lens group 20 includes a group of negative power cemented lenses and two positive power lenses in order from the object side to the image side. The projection lens 100 has the advantages of less lenses, simple structure and easy manufacture, so that the cost of the projection lens 100 is reduced. The number of lenses of the whole projection lens 100 is small, so that the transmittance of the whole projection lens 100 is high, and the aperture is large, thereby achieving the purpose of projecting high brightness.

While the projection lens 100 has only two groups, which means that only two lens groups, for example, the first lens group 10 and the second lens group 20, are provided.

Next, a specific embodiment of the projection lens 100 according to the present application will be described.

First, various possible implementations of the projection lens 100 provided by the present application are described below with reference to fig. 1, 5 and 9, and the projection lens 100 is specifically described in the first, second and third embodiments, where the structures and parameters in the first, second and third embodiments are merely examples of the implementation of the projection lens 100, and are not limited to the above configuration.

Table one (wherein aspherical) example one

Example two (wherein aspheric surface)

Example three (wherein aspheric surface)

In the column of the plane number Si in the lens data shown in table one, the plane of the component closest to the object side is shown as the first plane, and the plane number gradually increases along the image direction. In the column of the radius of curvature Ri, the value of the radius of curvature corresponding to the Si number is shown. In the column of the plane interval Di, the lens thickness or the interval value between lenses corresponding to the Si number is shown. The unit of the radius of curvature Ri and the face spacing Di is millimeters (mm). In columns of refractive index Ndj and abbe number vdj, the refractive index and abbe number of the j-th (j=1 to 9) optical element from the object side with respect to d-light (wavelength 587.6 nm) are shown, respectively.

Watch II

Embodiment one:

K

b

c

d

e

f

g

h

S3

-7.9E-01

-5.1E-05

4.0E-07

-5.2E-10

-7.2E-12

9.9E-15

4.2E-16

-1.6E-18

S4

-4.2E-01

-1.2E-04

7.1E-08

2.4E-09

-5.0E-11

-7.3E-14

4.1E-15

-1.9E-17

S16

0.0E+00

-2.1E-05

-3.9E-09

5.4E-11

5.3E-13

4.4E-15

-1.1E-16

3.3E-19

S17

7.0E-01

8.6E-06

8.0E-09

3.2E-10

7.4E-14

-1.2E-14

6.4E-17

-1.9E-19

embodiment two:

K

b

c

d

e

f

g

h

S3

-9.9E-01

-5.4E-05

4.1E-07

-5.1E-10

-7.3E-12

4.6E-15

4.2E-16

-1.5E-18

S4

-3.9E-01

-1.2E-04

9.4E-08

2.8E-09

-4.8E-11

-9.6E-14

3.9E-15

-1.7E-17

S16

0.0E+00

-2.4E-05

-1.5E-08

-7.1E-11

5.6E-13

1.3E-14

-1.7E-16

4.8E-19

S17

2.0E+00

8.1E-06

7.8E-09

1.0E-10

1.3E-12

-9.7E-15

1.5E-17

-7.8E-21

embodiment III:

K

b

c

d

e

f

g

h

S3

-8.9E-01

-5.4E-05

4.1E-07

-4.5E-10

-7.3E-12

7.6E-16

4.6E-16

-1.6E-18

S4

-4.1E-01

-1.2E-04

9.7E-08

2.6E-09

-4.7E-11

-9.2E-14

3.8E-15

-1.7E-17

S16

0.0E+00

-2.3E-05

-1.0E-08

-6.9E-11

8.0E-13

1.2E-14

-1.9E-16

5.9E-19

S17

2.3E+00

9.0E-06

1.5E-08

1.3E-10

1.3E-12

-9.9E-15

3.2E-18

4.7E-20

in table two, the symbol "E" indicates that the data immediately following it is a "power exponent" based on 10, which indicates that a value represented by an exponential function based on 10 is multiplied by a value before "E", which is shown as aspherical data. For example, if "1.0E-02", then "1.0X10-2" is indicated.

The data of the following Table II are aspherical coefficients, the aspherical coefficients are obtained by taking the center of the lens surface as the origin and the optical axis as the x-axis, and the aspherical surface expression of the lens surface satisfies the following formula (A)

The specific meaning of the relevant parameters in the above formula (A) is as follows

X- -depth of aspheric surface (mm),

y-distance (height) (mm) from the optical axis to the lens surface,

c-is the radius of curvature of the lens, c=1/R,

k-the conic constant,

b. c, d, e, f, g, h-aspherical lens coefficients.

In the following Table III, f is the paraxial focal length of the whole system in units of (mm), FN is the diaphragm, and 2ω is the viewing angle (ω: half viewing angle).

Table three:

embodiment one:

f	FNO.	2ω
			12.56	1.6	63.8°

embodiment two:

f	FNO.	2ω
			12.56	1.67	63.8°

embodiment III:

f	FNO.	2ω
			12.56	1.67	63.8°

in addition, table four describes specific values of the conditional expressions and examples of the present application.

Table four:

conditional expression	Example 1	Example two	Example III
				4<\|f1/f2︱<7	5.3	5.2	4.58
TTL/EFFL<10	9.16	9.12	9.15
				TTL/BFL<4.5	3.99	4.06	3.96
Vd11>50	64	64	64
				Vd12>50	55	55	64
Vd13<24	18	18	18
				Vd15<24	18	18	18
Vd21>64	81	81	81
				Vd23>64	81	81	81
Vd24>50	53	53	53
				f23/f2>1.0	1.15	1.17	1.17

From the above description of specific data of the embodiments, the following description is further drawn with reference to the accompanying drawings of the embodiments:

as can be seen from the MTF curves of fig. 2, 6, 10, the optical transfer function MTF is >65% for the full field of view at a spatial frequency of 93 lp/mm.

As can be seen from the distortion diagrams of fig. 3, 7 and 11, the maximum distortion of the full field of view is less than 0.5%.

As can be seen from the color difference diagrams of fig. 4, 8 and 12, the full-field vertical axis color difference is 1.5 μm at maximum.

From the imaging results and parameters of the projection lens 100 obtained in the above embodiments one to three, the MTF of the projection lens 100 of the present application is excellent, the distortion is small, the vertical axis chromatic aberration is small, and the aperture can reach F1.6. Moreover, the number of lenses is small, so that the transmittance of the whole projection lens 100 is high. Such a projection lens 100 not only has a good resolving power, but also can better utilize the light effect, so as to improve the brightness of the projection screen of the projector when the projector is used.

The present application is not limited to the above-described embodiments, and various modifications are possible. For example, the values of the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to those shown in the above-described numerical examples, and other values may be used. Such variations, which are in accordance with the spirit of the present application, are intended to be included within the scope of the application as claimed.

The application also provides a projector, which comprises the projection lens. The projection lens 100 of the projector has the advantages of less lenses, simple structure and easy manufacture, so that the cost of the projection lens is reduced, the cost of the projector is reduced, and the using effect of the projector is better.

While the preferred embodiments of the present application have been illustrated and described, the present application is not limited to the examples, and various equivalent modifications and substitutions can be made by one skilled in the art without departing from the spirit of the present application, and these equivalent modifications and substitutions are intended to be included in the scope of the present application as defined in the appended claims.

Claims

1. A projection lens, characterized in that:

the lens comprises a first lens group with positive focal power, a diaphragm and a second lens group with positive focal power in sequence from an object side to an image side;

and satisfies the following conditional expression:

4<|f1/f2︱<7

TTL/EFFL<10

TTL/BFL<4.5

f1: the focal length of the first lens group,

f2: the focal length of the second lens group,

EFFL: the focal length of the lens is set,

2. A projection lens according to claim 1, wherein:

the projection lens has only two groups.

3. A projection lens according to claim 1, wherein:

a diaphragm is arranged between the first lens group and the second lens group, and the position of the diaphragm is fixed.

4. A projection lens according to claim 1, wherein:

in the first lens group, the first lens is a meniscus lens, wherein the first surface and the second surface are both bent towards the image space; the second lens is a meniscus lens, wherein the first surface and the second surface are both bent towards the image space, and at least one surface is an aspheric surface; the third lens and the fourth lens are combined into a cemented lens, wherein the first surface of the third lens is bent towards the object, the second surface of the fourth lens is bent towards the object, and the cemented lens of the combined lens is bent towards the object or towards the image; the fifth lens is a biconvex positive lens.

5. A projection lens according to claim 4, wherein:

the first lens group satisfies the following conditional expression:

Vd11>50

Vd12>50

Vd13<24

Vd15<24

vd11: the first lens group has a first sheet lens abbe number,

vd15: the first lens group fifth lens element has a dispersion coefficient.

6. A projection lens according to claim 1, wherein:

the first lens and the second lens in the second lens group are combined into a cemented lens, wherein the first surface of the cemented lens is bent towards the object side or towards the image side, the second surface of the cemented lens is bent towards the object side, and the third surface of the cemented lens is bent towards the object side or towards the image side; the third lens is a biconvex positive lens; the fourth lens is a positive lens, wherein the first surface is bent towards the object side or towards the image side, the second surface is bent towards the object side, and at least one surface is an aspheric surface.

7. A projection lens according to claim 6, wherein:

the second lens group of the projection lens satisfies the following conditional expression:

Vd21>64

Vd23>64

Vd24>50

f23/f2>1.0

vd21: the abbe number of the first lens of the second lens group,

vd23: the abbe number of the third lens of the second lens group,

vd24: the abbe number of the fourth lens of the second lens group,

f23: focal length of the third lens of the second lens group,

f2: focal length of the second lens group.

8. A projector comprising the projection lens of any one of claims 1 to 7.