CN115220182A

CN115220182A - Projection lens and projector

Info

Publication number: CN115220182A
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: 2022-10-21
Anticipated expiration: 2042-06-23
Also published as: CN115220182B

Abstract

The invention 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 consists of 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 in sequence. The second lens group comprises a group of negative focal power cemented lens and two lenses with positive focal power from the object side to the image side in sequence. The projection lens has the advantages of small number of lenses, simple structure and easy manufacture, and reduces the cost of the projection lens. The whole lens is small in lens quantity, so that the transmittance of the whole lens is high, and the aperture is large, so that the purpose of high projection brightness is achieved.

Description

Projection lens and projector

Technical Field

The invention relates to the technical field of image display, in particular to a projection lens and a projector.

Background

The projector is used as a necessary projection device in various places in life such as teaching and cinema, the projection lens is the last link in the optical 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 micro-mirror Device) or an LCOS (Liquid Crystal On Silicon) as a display Device, uses a polarization beam splitter element or a total reflection beam splitter element as an illumination or imaging beam splitter, and focuses an image reflected On the display Device onto a projection screen through a projection lens optical path designed reasonably.

The investigation finds that the projection image quality of the 0.47' telecentric projection lens on the market is poor. And because more lenses or more plastic lenses are used, the transmittance of the whole lens is low, and the finally projected brightness is low. The present invention has been made to solve the above-mentioned problems.

Disclosure of Invention

The present invention is directed to a projection lens and a projector, which solves one or more of the problems of the prior art and provides at least one of the advantages of the present invention.

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

the invention 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 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 in sequence;

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

and satisfies the following conditional expressions:

4<|f1/f2︱<7

TTL/EFFL<10

TTL/BFL<4.5

wherein the content of the first and second substances,

f1: the focal length of the first set of lenses,

f2: the focal length of the second group of lenses,

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 to be,

BFL: and 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 invention has the beneficial effects that:

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

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

As a further improvement of the above technical solution, in the first lens group, the first lens is a meniscus lens, wherein the first surface and the second surface are both curved toward the image; 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 space, the second surface of the fourth lens is bent towards the object space, and the cemented surface of the combined lens can be bent towards the object space and the image space; 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

wherein, the first and the second end of the pipe are connected with each other,

vd11: the first lens group has a first lens dispersion coefficient,

vd12: the dispersion coefficient of the second lens of the first lens group,

vd13: the dispersion coefficient of the third lens of the first lens group,

vd15: the fifth lens of the first lens group has an Abbe number.

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 surface of the cemented lens may be curved toward the object side or the image side, a second surface of the cemented lens may be curved toward the object side, and a third surface of the cemented lens may be curved toward the object side or the image side; the third lens is a biconvex positive lens; the fourth lens is a positive lens, wherein the first surface can be bent towards the object side or 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

wherein the content of the first and second substances,

vd21: the dispersion coefficient of the first lens of the second lens group,

vd23: the coefficient of dispersion of the third lens of the second lens group,

vd24: the dispersion coefficient of the fourth lens of the second lens group,

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

f2: focal length of the second lens group.

The invention also provides a projector which comprises the projection lens.

Drawings

The invention is further explained by the following figures and embodiments;

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

Fig. 2 shows MTF curves of a projection lens according to an embodiment of the present invention.

Fig. 3 is a diagram illustrating a distortion of a projection lens according to an embodiment of the invention.

Fig. 4 is a diagram illustrating a chromatic aberration of a projection lens according to an embodiment of the present invention.

Fig. 5 is a view showing a configuration of a projection lens according to a second embodiment of the present invention.

Fig. 6 shows MTF curves of the projection lens according to the second embodiment of the present invention.

Fig. 7 is a distortion diagram of a projection lens according to a second embodiment of the present invention.

Fig. 8 is a chromatic aberration diagram of a projection lens according to a second embodiment of the present invention.

Fig. 9 is a view showing a configuration of a projection lens according to a third embodiment of the present invention.

Fig. 10 shows MTF curves of the projection lens according to the third embodiment of the present invention.

Fig. 11 is a distortion diagram of a projection lens according to a third embodiment of the present invention.

Fig. 12 is a chromatic aberration diagram of a projection lens according to a third embodiment of the present invention.

Reference numerals are as follows: 10 denotes a first lens group; 20 a second lens group; 30 denotes an aperture; 40 denotes a vibrating piece; 50 denotes a prism in the illumination system; DMD cover glass 60; 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 preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, if words such as "a", "an", etc. are used, the meaning is one or more, the meaning of a plurality is two or more, less, more, etc. are understood as excluding the present number, and more, less, more, etc. are understood as including the present number.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1 to 12, a projection lens 100 and a projector according to the present invention are as follows:

fig. 1 shows a projection lens 100 according to a first embodiment of the present invention. The projection lens 100 includes, in order from an object side to an image side: a first lens group 10 having positive power, a second lens group 20 having positive power, 30 representing an aperture stop; 40 denotes a vibrating piece; 50 denotes a prism in the illumination system; DMD cover glass 60; 70 denotes an image plane; 100 denotes an entire projection lens system configuration.

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,

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

EFFL: the focal length of the lens is set to be,

BFL: the distance between the second surface of the last lens of the second lens group 20 and the image surface of the DMD.

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

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

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

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

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

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

wherein the content of the first and second substances,

vd21: the second lens group 20 has the first lens element Abbe's number,

vd23: the second lens group 20 has the third lens element Abbe's index,

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

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

f2: focal length of the second lens group 20.

The invention discloses a projection lens 100, which comprises the following components in sequence from an object side to an image side: a first lens group 10 with positive power, a stop, a second lens group 20 with positive power. The first lens group 10 is composed of two negative focal power lenses, a group of negative focal power cemented lenses and a positive focal power lens in sequence from the object side to the image side. The second lens group 20 includes, in order from the object side to the image side, a group of negative focal power cemented lenses and two positive focal power lenses. The projection lens 100 has a small number of lenses, a simple structure, and easy manufacturing, 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 high projection brightness.

And the projection lens 100 has only two groups, which means that only two lens groups, such as 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 invention will be described.

First, there are many possible implementation manners of the projection lens 100 provided by the present invention, and the projection lens 100 is specifically described below by taking the first embodiment, the second embodiment and the third embodiment as examples with reference to fig. 1, fig. 5 and fig. 9, and the structures and parameters in the first embodiment, the second embodiment and the third embodiment are only examples of the implementation manners of the projection lens 100, and are not limited to be set as such.

Watch one (wherein a ball surface)

Example one

Example two (where a. Aspheric surface)

EXAMPLE three (where a. Aspheric surface)

In the column of the surface number Si in the lens data shown in table one, it is shown that the surface of the component closest to the object side is the first surface, and the surface number is gradually increased 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 face separation Di, the lens thickness or the value of the space between lenses corresponding to the Si number is shown. The unit of the radius of curvature Ri and the face separation Di is millimeters (mm). In the columns of refractive index Ndj and abbe number vdj, values of 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 2

The first embodiment is as follows:

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

the second embodiment:

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

example three:

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, data is shown as aspherical surface data, and the symbol "E" indicates the "power exponent" immediately after the data is base 10, and indicates the value before the value represented by the base 10 exponential function is multiplied by "E". For example, if it is "1.0E-02", it means "1.0X10-2".

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

The specific meanings of the relevant parameters in the above formula (A) are as follows

X- -the depth (mm) of the aspheric surface,

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

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

k- -a conic constant,

b. c, d, e, f, g, h-aspheric lens coefficient.

In the third table below, f is the paraxial focal length of the entire system in (mm), FNO is the aperture, and 2 ω is the view angle (ω: half view angle).

A third table:

the first embodiment is as follows:

f	FNO.	2ω
			12.56	1.6	63.8°

the second embodiment:

f	FNO.	2ω
			12.56	1.67	63.8°

example three:

f	FNO.	2ω
			12.56	1.67	63.8°

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

Table four:

conditional formula (II)	Example one	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 the embodiment specific data, further description is made with reference to the embodiment drawings:

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

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

As can be seen from the color difference graphs of FIG. 4, FIG. 8 and FIG. 12, the maximum vertical axis color difference of the full view field is 1.5 μm.

As can be seen from the imaging results and parameters of the projection lens 100 obtained in the first to third embodiments, the projection lens 100 of the present invention has excellent MTF performance, small distortion, small vertical axis chromatic aberration, and a diaphragm F1.6. Moreover, since the number of the lenses is small, the transmittance of the whole projection lens 100 is high. The projection lens 100 not only has good image resolving capability, but also can better utilize light effect, thereby improving the brightness of a projection picture of a projector when the projection lens is used on the projector.

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

The invention also provides a projector which comprises the projection lens. The projection lens 100 of the projector has the advantages of small number of 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 invention have been described in detail, it is to be understood that the invention is not limited to the precise embodiments, and that various equivalent changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention 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;

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

and satisfies the following conditional expressions:

4<|f1/f2︱<7

TTL/EFFL<10

TTL/BFL<4.5

wherein the content of the first and second substances,

f1: the focal length of the first set of lenses,

f2: the focal length of the second group of lenses,

EFFL: the focal length of the lens is set to be,

2. The projection lens of claim 1, wherein:

the projection lens has only two groups.

3. The projection lens of claim 1, wherein:

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

4. The projection lens of claim 1, wherein:

in the first lens group, a first lens is a meniscus lens, and a first surface and a second surface are both bent towards the image; 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 space, the second surface of the fourth lens is bent towards the object space, and the cemented surface of the combined lens can be bent towards the object space and can also be bent towards the image space; the fifth lens is a biconvex positive lens.

5. The projection lens of claim 4, wherein:

the first lens group satisfies the following conditional expression:

Vd11>50

Vd12>50

Vd13<24

Vd15<24

wherein the content of the first and second substances,

vd11: the first lens group has a first lens dispersion coefficient,

vd12: the first lens group and the second lens sheet have dispersion coefficients,

vd13: the third lens dispersion coefficient of the first lens group,

vd15: the fifth lens of the first lens group has an abbe number.

6. The projection lens of 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 can be bent towards the object space and the image space, the second surface of the cemented lens is bent towards the object space, and the third surface of the cemented lens can be bent towards the object space and the image space; the third lens is a biconvex positive lens; the fourth lens is a positive lens, wherein the first surface can be bent towards the object side or the image side, the second surface is bent towards the object side, and at least one surface is an aspheric surface.

7. The projection lens of 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 dispersion coefficient of the first lens of the second lens group,

vd23: the dispersion coefficient of the third lens of the second lens group,

vd24: the dispersion coefficient of the fourth lens of the second lens group,

f23: the 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 according to any one of claims 1 to 7.