CN115840279A - Projection lens and projection equipment - Google Patents

Abstract

The invention discloses a projection lens and projection equipment, comprising: the image sensor sequentially comprises the following components from an object side to an image side: a first lens group with positive focal power, a diaphragm, a second lens group with positive focal power; the first lens group comprises two negative focal power lenses, a group of negative focal power cemented lenses and a lens with positive focal power in sequence from the object side to the image side; 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; the projection lens has fewer lenses, improves the transmittance of the lens and improves the projection brightness.

Description

Projection lens and projection equipment

Technical Field

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

Background

The projection device is 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 projection device and is also an extremely important link, and the design of the projection lens not only influences the performance of the projection device, 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 or a total reflection beam splitter 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 0.33' 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.

Disclosure of Invention

The present invention is directed to a projection lens and a projection apparatus, which solves one or more of the problems in 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 present invention provides a projection lens, comprising:

the image sensor sequentially comprises the following components from an object side to an image side: a first lens group with positive focal power, a diaphragm, a second lens group with positive focal power;

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

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 satisfying the following conditional expressions:

5<|f1/f2︱<10

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

The beneficial effects of the invention are:

the projection lens has fewer lenses, improves the transmittance of the lens, and improves the projection brightness. And the length of the lens is reduced as much as possible under the condition of ensuring that the BFL is large enough. Therefore, the back focus has enough space to simultaneously realize the functional requirements of the 540P and 1080P lenses.

As a further improvement of the above technical solution, a stop is disposed between the first lens group and the second lens group of the projection lens. The diaphragm is used to control the throughput of light.

As a further improvement of the technical scheme, the position of the diaphragm is fixed and unchanged, so that the design of a mechanism can be facilitated.

As a further improvement of the above technical solution, the projection lens further includes a prism, and the prism is disposed between the second lens group and the image plane.

As a further improvement of the technical scheme, a vibration sheet is arranged between the prism and the second lens group and is mainly used for achieving the 1080P purpose through vibration.

As a further improvement of the above technical solution, the first lens group is characterized in that: 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 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 of the projection lens 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 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 second lens group is characterized in that: the first lens and the second lens are combined into a cemented lens, wherein the first surface of the cemented lens can be bent towards the object space or 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 or 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.

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

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.

The invention also provides projection equipment comprising the projection lens. The projection equipment uses a small number of lenses, so that the transmittance of the whole lens is high. The lens not only has good image resolving capability, but also can better utilize light effect, thereby improving the brightness of a projection picture of the projection equipment when the lens is used on the projection equipment.

Drawings

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

fig. 1 is a view showing a structure 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 present 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 a projection lens according to a 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.

10 denotes a first lens group; 20 denotes a second lens group; 30 denotes an aperture; 40 denotes a vibrating piece; 50 denotes a prism; DMD cover glass 60; 70 denotes an image plane; and 100 denotes a projection lens.

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 plurality" are described, the meaning is one or more, the meaning of a plurality is two or more, more than, less than, more than, etc. are understood as excluding the present number, and more than, less than, 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 8, a projection lens and a projection apparatus according to the present invention are as follows:

in 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, and a second lens group 20 having positive power.

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

5<|f1/f2︱<10---------------(1)

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

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

wherein the content of the first and second substances,

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

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

TTL: 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.

The projection lens 100 further includes a diaphragm 30 and an oscillating plate 40. The diaphragm is located between first battery of lens 10 and second battery of lens 20 to the restriction process the light entering of first battery of lens 10 the luminous flux of second battery of lens 20, and let the process the light cone behind the first battery of lens 10 can be more symmetrical, make projection lens 100's coma is revised. To facilitate the design of the mechanism, the diaphragm position is set to a fixed position. It should be noted that, for the sake of simplicity, the projection lens 100 is simply referred to as a lens.

The oscillating sheet 40 is located between the second lens group 20 and one prism 50, and is mainly used for achieving the 1080P purpose through oscillation. Of course, the oscillating plate 40 can be eliminated. When the oscillating plate 40 is not provided in the design, the projected output is the original pixel of DMD. The prism 50 to be explained may also be a prism 50 in the illumination system. And 60, DMD protective glass for protecting the image plane-placed imaging element.

In this embodiment, the first lens group 10 includes, in order from an object side to an image side: 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 both surfaces are aspheric surfaces; 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 image space; the fifth lens is a biconvex positive lens.

The first lens group 10 of the projection lens 100 is configured to satisfy the following conditional expressions (4), (5), (6), and (7):

Vd11>50---------------(4)

Vd12>50---------------(5)

Vd13<24---------------(6)

Vd15<24---------------(7)

wherein the content of the first and second substances,

vd11: the first lens group 10 has a first lens abbe number,

vd12: the first lens group 10 has a second lens abbe number.

Vd13: the third lens abbe number of the first lens group 10,

vd15: the first lens group 10 has a fifth lens abbe number.

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 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 abbe 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.

Next, the operation and effect of the projection lens configured as described above will be described.

Conditional expressions (1) to (3) specify the geometric dimensions of the projection lens 100, and ensure that the length of the lens is reduced as much as possible when the BFL is sufficiently large. Therefore, the back focus has enough space to simultaneously realize the functional requirements of the 540P and 1080P lenses. Meanwhile, the length of the lens is shortened, the outer diameter of the lens can be reduced, and the purpose of reducing cost is achieved.

Conditional expressions (4) to (6) specify the dispersion of the key lens of the first lens group 10. The system chromatic aberration can be effectively corrected by meeting the conditional expression.

Conditional expressions (7) to (10) specify the dispersion of the key lens of the second lens group 20. The system chromatic aberration can be effectively corrected by meeting the conditional expression.

Conditional expression (11) specifies the assignment of the key lens power of the second lens group 20. The variable quantity of high and low temperature analysis can be effectively corrected by meeting the conditional expression, and the requirement of assembly tolerance is met. 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 and the second embodiment as examples, but the structures and parameters in the first embodiment and the second embodiment are only examples of implementation manners of the projection lens 100, and are not limited to being necessarily set as such.

In the column of the surface number Si in the lens data shown in tables one and two, it is shown that the surface of the component closest to the object side is the first surface, and the surface number increases gradually 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 columns of the refractive index Ndj and the abbe number vdj, values of the refractive index and the abbe number of the j-th optical element (j =1 to 9) from the object side with respect to d-light (wavelength 587.6 nm) are shown, respectively. Note that, denotes an aspherical surface. Table one: the first embodiment is as follows:

table two: example two

In tables three and four, data is shown as aspherical data, and the symbol "E" indicates that the data immediately after it is a "power exponent" with a base 10, and indicates a value before multiplying a value represented by an exponential function with a base 10 by "E". For example, if "1.0E-02", this means "1.0X10-2". Note that, denotes an aspherical surface.

Table three: example one

K

b

c

d

e

f

g

h

S3

-2.6E-01

-1.6E-04

1.5E-06

-5.5E-09

-9.3E-11

5.5E-13

6.6E-15

-6.0E-17

S4

-2.7E-01

-3.6E-04

-1.7E-06

4.3E-08

-1.3E-09

-5.3E-12

3.6E-13

-3.5E-15

S16

1.2E-02

-3.5E-05

1.4E-08

-1.7E-10

3.2E-12

7.8E-14

6.0E-18

-6.2E-18

S17

2.0E-03

2.9E-05

4.1E-08

6.7E-10

1.5E-12

5.4E-14

7.4E-16

-9.3E-18

Table four: example two

K

b

c

d

e

f

g

h

S3

-1.6E-01

-1.5E-04

1.4E-06

-4.3E-09

-8.0E-11

6.2E-13

6.1E-15

-8.6E-17

S4

-2.6E-01

-3.5E-04

-1.9E-06

4.1E-08

-1.3E-09

-5.0E-12

3.5E-13

-3.9E-15

S16

0.0E+00

-3.4E-05

4.8E-09

-1.6E-10

2.7E-12

6.2E-14

-2.3E-19

-4.4E-18

S17

0.0E+00

2.9E-05

3.2E-08

4.6E-10

1.9E-12

4.6E-14

7.2E-16

-8.3E-18

Taking the data in the following table five and table six as aspheric surface coefficients, wherein the aspheric surface coefficients take the center of the lens surface as an original point, the optical axis as an x axis, and the aspheric surface type expression of the lens surface meets the following formula (A);

the relevant parameters in the above formula (a) have the following specific meanings:

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).

Table five: example one

f	FNO.	2ω
			9.04	1.7	63.2°

Table six: example two

f	FNO.	2ω
			9.04	1.7	63.4°

In addition, table seven describes the conditions and specific values of the examples of the present invention.

TABLE VII:

conditional formula (II)	Example one	Example two
			5＜|f1/f2|＜10	9.4	6.87
TTL/EFFL＜10	9.79	9.79
			TTL/BFL＜4.5	3.33	3.47
Vd11＞50	64	64
			Vd12＞50	55	55
Vd13＜24	18	18
			Vd15＜24	23.8	23.8
Vd21＞64	81	81
			Vd23＞64	81	81
Vd24＞50	59.4	59.4
			f23/f2＞1.0	1.15	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 graphs of FIG. two and FIG. six MTF, 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 graphs of fig. three and fig. seven, the maximum distortion of the full field is less than 0.5%.

As can be seen from the color difference graphs of the fourth graph and the eighth graph, 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 above embodiments, the projection lens 100 of the present invention has excellent MTF performance, small distortion, small vertical axis chromatic aberration, and a diaphragm F1.7. And because the number of the lenses is small, the transmittance of the whole lens is high. The lens has good image resolving capability and can better utilize light effect, so that the brightness of a projection picture of the projection equipment is improved when the lens is used on the projection equipment.

The invention also provides a projection device comprising the projection lens 100. The projection equipment uses a small number of lenses, so that the transmittance of the whole lens is high. The lens has good image resolving capability and can better utilize light effect, so that the brightness of a projection picture of the projection equipment is improved when the lens is used on the projection equipment.

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 within the spirit of the invention and are within the scope of the invention as claimed.

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 (10)

1. A projection lens, comprising:

the image sensor sequentially comprises the following components from an object side to an image side: a first lens group having positive power, a second lens group having positive power;

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

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 satisfying the following conditional expressions:

5<|f1/f2︱<10

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

2. A projection lens according to claim 1, characterized in that:

and a diaphragm is arranged between the first lens group and the second lens group of the projection lens.

3. The projection lens of claim 2, wherein:

the position of the diaphragm is fixed.

4. The projection lens of claim 1, wherein:

the projection lens further comprises a prism, and the prism is arranged between the second lens group and the image surface.

5. The projection lens of claim 4, wherein:

and a vibration sheet is arranged between the prism and the second lens group.

6. The projection lens of claim 1, wherein:

the first lens group is characterized in that: 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 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.

7. The projection lens of claim 1, wherein:

the projection lens 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 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.

8. A projection lens according to claim 1, characterized in that:

the second lens group is characterized in that: the first lens and the second lens are combined into a cemented lens, wherein the first surface of the cemented lens can be bent towards the object space or 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 or 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.

9. A projection lens according to claim 1, characterized in that:

the second lens group of the projection lens meets 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 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.

10. A projection apparatus comprising the projection lens according to any one of claims 1 to 9.

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