CN113608331B

CN113608331B - Projection lens and projection equipment

Info

Publication number: CN113608331B
Application number: CN202110740637.4A
Authority: CN
Inventors: 赵云
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2023-03-17
Anticipated expiration: 2041-06-30
Also published as: CN113608331A

Abstract

The present disclosure provides a projection lens and a projection apparatus, the projection lens includes a lens front group and a lens rear group in order from an image side to an object side; wherein the front lens group comprises at least five lenses and has negative focal power; the lens rear group at least comprises four lenses, and the lens rear group has positive focal power. The present disclosure enables high precision projection using fewer lenses while avoiding the use of a reflective bowl.

Description

Projection lens and projection equipment

Technical Field

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

Background

With the development of the micro projector technology, the ultra-short focus projector gradually enters the field of vision of people. At present, the micro projector is mainly applied to the fields of family entertainment, education and learning, business meetings, military affairs and the like. In the field of projectors, the throw ratio is a key parameter, the lower the throw ratio is, the shorter the distance between the projector and a wall surface is, and the smaller the occupied space is, but the larger the angle of view is, and the higher the design difficulty is.

At present, the projection ratio of a projector is gradually reduced, and two mainstream design schemes are adopted, namely one scheme is provided with a light reflecting bowl, and the other scheme is not used. The disadvantages of the two schemes are explained separately below.

The light reflecting bowl is arranged: the reflecting surface of the reflecting bowl is generally an aspheric surface or a free-form surface and is used for bearing more aberration correction, but the reflecting bowl has large focal power, so that the tolerance of the reflecting bowl is very sensitive, the architecture of the reflecting bowl is caused, and the assembling difficulty and the time consumption of the reflecting bowl are higher.

No reflector: because the structure does not use a reflector, more lenses are generally needed to correct aberration, and the projection lens meeting the requirements of distortion, CRA (chief ray angle), definition and the like at present generally adopts more than 11 lenses, and the more lenses can ensure the optical performance of the lens, but bring more assembly tolerances, so that the assembly difficulty is increased.

Disclosure of Invention

The purpose of the present disclosure is to provide a projection lens and a projection apparatus, so as to realize high-precision projection by using fewer lenses under the condition of avoiding using a reflection bowl.

The embodiment of the first aspect of the present disclosure provides a projection lens, which includes, in order from an image side to an object side, a front lens group and a rear lens group; wherein the content of the first and second substances,

the front lens group comprises at least five lenses and has negative focal power;

the lens rear group at least comprises four lenses, and the lens rear group has positive focal power.

According to some embodiments of the present disclosure, the front lens group includes, in order from an image side to an object side, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, and the optical powers are sequentially set to negative, positive, and negative.

According to some embodiments of the present disclosure, the rear lens group includes, in order from an image side to an object side, a sixth lens, a seventh lens, an eighth lens, and a ninth lens, and the optical powers are sequentially set to negative, positive, and positive.

According to some embodiments of the present disclosure, the first lens and the second lens constitute a first cemented doublet structure; the sixth lens and the seventh lens constitute a second double cemented structure.

According to some embodiments of the present disclosure, the first lens is a convex-concave lens with a concave surface facing the object, the second lens is a meniscus lens with a concave surface facing the object, the third lens is a convex-concave lens with a concave surface facing the object, the fourth lens is a biconvex lens, the fifth lens is a convex-concave lens with a concave surface facing the object,

according to some embodiments of the present disclosure, the sixth lens is a convex-concave lens with a concave surface facing the object, the seventh lens is a biconvex lens, the eighth lens is a biconvex lens, and the ninth lens is a biconvex lens.

According to some embodiments of the present disclosure, both surfaces of the first lens, the second lens, the third lens, the eighth lens, and the ninth lens are aspheric.

According to some embodiments of the present disclosure, both surfaces of the fourth lens, the fifth lens, the sixth lens, and the seventh lens are spherical surfaces.

According to some embodiments of the disclosure, both surfaces of all lenses in the projection lens are coated with antireflection coatings.

An embodiment of a second aspect of the present disclosure provides a projection apparatus, including the projection lens described in the first aspect.

In the projection lens and the projection equipment provided by the disclosure, the projection lens sequentially comprises a lens front group, an aperture diaphragm, a lens rear group, a prism and a spatial modulation device from an image space to an object space. Wherein, the projection light of spatial modulation device forms images to the image space through group before prism, lens back group, aperture diaphragm and the lens in proper order, because aspheric lens is used at this application projection lens's both ends, to the camera lens of big angle of vision, can reduce marginal aberration, consequently this application can use less lens to realize the high accuracy projection under the condition of avoiding using the reflection bowl.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the disclosure. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 shows a schematic diagram of a projection lens provided by the present disclosure;

FIG. 2 shows a schematic view of various optical surfaces on a projection lens provided by the present disclosure;

fig. 3 shows a schematic optical path diagram of a projection lens provided by the present disclosure.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.

It should be noted that all the directional indicators (such as upper, lower, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the motion situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Fig. 1 shows a schematic diagram of a projection lens provided by the present disclosure; the projection lens provided by the disclosure comprises a lens front group and a lens rear group in sequence from an image side to an object side; as shown in fig. 1, the device specifically includes a lens front group, an aperture stop, a lens rear group, a prism, and a spatial modulation device from an image side to an object side;

the front lens group at least comprises five lenses and has negative focal power; the lens rear group at least comprises four lenses, and the lens rear group has positive focal power.

Specifically, as shown in fig. 1, the lens front group includes a first lens GM1, a second lens GM2, a third lens GM3, a fourth lens G4 and a fifth lens G5, which are arranged in order from the light exit end to the light entry end, and the lens front group has a negative focal power; the lens rear group includes a sixth lens G6, a seventh lens G7, an eighth lens GM8, and a ninth lens GM9, which are arranged in this order from the light exit end to the light entrance end, and has positive refractive power.

In the application, the lens front group comprises 3 aspheric lenses, and the 3 aspheric lenses are positioned at the foremost end of the projection lens; the rear lens group comprises 2 aspheric lenses, and the 2 aspheric lenses are positioned at the rearmost end of the projection lens. For large field lenses, the aberrations of the peripheral field dominate, and the most effective way to reduce the peripheral aberrations is to use aspheric lenses at both ends of the lens.

In addition, protective glass can be arranged between the prism and the spatial modulation device, the size of the protective glass is set to be not smaller than that of the spatial modulation device, and the spatial modulation device can be isolated and protected through the protective glass.

In the present application, the front and back surfaces of all optical lenses are coated with antireflection films to reduce or eliminate the reflected light from the optical surfaces such as lenses and prisms, thereby increasing the amount of light transmitted by these elements and reducing or eliminating the stray light of the system.

In the embodiment, more aspheric surfaces are used to replace the traditional reflection bowl, the assembling difficulty and the processing difficulty of the projection lens are reduced, the number of lenses is reduced, and the assembling tolerance sensitivity and the processing cost are reduced.

Specifically, as shown in fig. 1, the first lens GM1 is a convex-concave lens with a concave surface facing the object, the second lens GM2 is a meniscus lens with a concave surface facing the object, the third lens GM3 is a convex-concave lens with a concave surface facing the object, the fourth lens G4 is a biconvex lens, the fifth lens G5 is a convex-concave lens with a concave surface facing the object, the sixth lens G6 is a convex-concave lens with a concave surface facing the object, the seventh lens G7 is a biconvex lens, the eighth lens GM8 is a biconvex lens, and the ninth lens GM9 is a biconvex lens.

Specifically, as shown in fig. 1, the first lens GM1 and the second lens GM2 constitute a first cemented doublet structure; the sixth lens G6 and the seventh lens G7 constitute a second double cemented structure, and the cemented lens can reduce aberrations during high-resolution imaging or low-resolution imaging.

Specifically, both surfaces of the first lens GM1, the second lens GM2, the third lens GM3, the eighth lens GM8, and the ninth lens GM9 are aspheric. Both surfaces of the fourth lens G4, the fifth lens G5, the sixth lens G6, and the seventh lens G7 are spherical. It is understood that both sides refer to the front and back surfaces of the lens.

It should be understood that the projection lens of this application adopts multiunit multichip structure, and spherical lens and aspheric lens cooperation are used, and the rational use aspheric lens can effectively reduce projection lens structure complexity, reduces lens use quantity.

Specifically, the refractive index and abbe number of the first lens are 1.52 and 81.6, respectively, the refractive index and abbe number of the second lens are 1.51 and 82, respectively, the refractive index and abbe number of the third lens are 1.56 and 61, respectively, the refractive index and abbe number of the fourth lens are 1.82 and 30, respectively, the refractive index and abbe number of the fifth lens are 1.77 and 82, respectively, the refractive index and abbe number of the sixth lens are 1.96 and 17.5, respectively, the refractive index and abbe number of the seventh lens are 1.59 and 41.2, respectively, the refractive index and abbe number of the eighth lens are 1.52 and 54.2, respectively, and the refractive index and abbe number of the ninth lens are 1.73 and 81.9, respectively.

Specifically, the first lens has a negative focal power, the second lens has a negative focal power, the third lens has a negative focal power, the fourth lens has a positive focal power, the fifth lens has a negative focal power, the sixth lens has a negative focal power, the seventh lens has a positive focal power, the eighth lens has a positive focal power, and the ninth lens has a positive focal power.

The specific parameters of the lens power and profile are given in table 1 below.

TABLE 1

In order to effectively improve the optical performance of the projection lens, the basic optical design parameters of the projection lens of the present application are shown in table 2 below, where the parameters include the surface type of the lens, the curvature radius R (mm), the distance (mm) between the front and rear lens surfaces, the refractive index, the abbe number, and the half-aperture (mm) (the radius of the circular lens), where the surface numbers of the first lens GM1 are S1 and S2, and the rest of the lenses are analogized, as shown in fig. 2. OBJ denotes a projection object plane, for example, projected onto a wall surface. STOP denotes the STOP face on which the aperture STOP is located. IMA denotes an image plane of a spatial modulation device.

TABLE 2

In this application, the aspheric surface shape equation adopted by the aspheric optical lens is as follows:

wherein the content of the first and second substances,

c is the curvature of the aspheric apex, K is the conic coefficient, A ₁ ，A ₂ ，A ₃ ，A ₄ ，A ₅ The aspherical surface coefficient is of a high order, Z is a shift amount in the optical axis direction, and r is an aspherical surface height, i.e., a height from the center of the lens to the edge of the lens.

The basic data for the aspherical surface in the present application are as follows in table 3.

Noodle

K

A ₁

A ₂

A ₃

A ₄

A ₅

S1

4.434

0

-1.95E-005

-6.21E-008

2.69E-011

-4.80E-014

S2

-0.065

0

4.94E-005

3.41E-007

-4.93E-010

0

S3

-0.018

0

5.32E-005

-7.07E-007

-2.99E-009

0

S4

-0.756

0

-2.18E-004

-1.93E-006

2.03E-009

-2.91E-010

S5

0.346

0

6.21E-005

4.470E-007

-5.92E-009

-1.52E-010

S6

-0.407

0

3.28E-004

-3.96E-006

3.29E-008

-3.54E-010

S14

-12.827

0

1.18E-004

-6.65E-007

-6.17E-008

-2.71E-009

S15

1.826

0

-1.03E-004

-6.61E-006

1.94E-007

-1.23E-009

S16

31.898

0

3.99E-005

-6.48E-007

1.55E-007

-2.90E-009

S17

-8.695

0

1.08E-004

1.25E-005

-5.98E-009

-1.45E-009

TABLE 3

In addition, the spatial modulation Device in the present application may be a DMD (Digital micro-mirror Device), a laser, an LCOS (Liquid Crystal On Silicon, or Liquid Crystal On chip), an LCD (Liquid Crystal display), or the like.

The projection lens provided by the disclosure comprises a lens front group, an aperture diaphragm, a lens rear group, a prism and a spatial modulation device from an image side to an object side. Wherein, the projection light of spatial modulation device forms images to the image space through group before prism, lens back group, aperture diaphragm and the lens in proper order, because aspheric lens is used at this application projection lens's both ends, to the camera lens of big angle of vision, can reduce marginal aberration, consequently this application can use less lens to realize the high accuracy projection under the condition of avoiding using the reflection bowl.

Corresponding to the projection lens, the application also provides a projection device which comprises the projection lens.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the disclosure, and these alternatives and modifications are intended to fall within the scope of the disclosure.

Claims

1. The projection lens is characterized by comprising a lens front group and a lens rear group in sequence from an image side to an object side; wherein, the first and the second end of the pipe are connected with each other,

the lens front group consists of five lenses and has negative focal power;

the rear lens group consists of four lenses and has positive focal power;

the front lens group sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an image space to an object space, and the focal power is sequentially set to be negative, positive and negative;

the rear lens group comprises a sixth lens, a seventh lens, an eighth lens and a ninth lens from an image space to an object space in sequence, and focal power is sequentially set to be negative, positive and positive.

2. The projection lens of claim 1 wherein the first lens and the second lens form a first cemented doublet; the sixth lens and the seventh lens constitute a second double cemented structure.

3. The projection lens as claimed in claim 1 wherein the first lens is a convex-concave lens with a concave surface facing the object, the second lens is a meniscus lens with a concave surface facing the object, the third lens is a convex-concave lens with a concave surface facing the object, the fourth lens is a biconvex lens, and the fifth lens is a convex-concave lens with a concave surface facing the object.

4. The projection lens of claim 1 wherein the sixth lens element is a convex-concave lens element with a concave surface facing the object, the seventh lens element is a biconvex lens element, the eighth lens element is a biconvex lens element, and the ninth lens element is a biconvex lens element.

5. The projection lens of claim 1 wherein both surfaces of the first lens, the second lens, the third lens, the eighth lens and the ninth lens are aspheric.

6. The projection lens of claim 5 wherein the fourth, fifth, sixth and seventh lenses are spherical on both sides.

7. The projection lens according to any one of claims 1 to 6, wherein both surfaces of all lenses in the projection lens are coated with antireflection films.

8. Projection apparatus, characterized in that it comprises a projection lens according to any of claims 1 to 7.