CN219266646U - Projection lens and projection equipment - Google Patents

Abstract

The present disclosure provides a projection lens and a projection apparatus, the projection lens including a lens group having positive optical power; the lens group sequentially comprises a first lens, a second lens, a third lens and a fourth lens from an image space to an object space, and the focal power is sequentially set to be positive, negative and positive. The projection light of the image source sequentially passes through each lens in the lens group to form an image in the image space, and the projection lens of the image source only uses four lenses, so that the number of the lenses is small, the production cost and the assembly difficulty can be reduced, and the reliability of the projection lens can be improved.

Description

Projection lens and projection equipment

Technical Field

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

Background

With the development of micro projector technology, ultra-short focal projectors gradually enter the field of view of people. The present micro projector is mainly applied to the fields of home entertainment, education and study, business meetings, military and the like, such as an AR (Augmented Reality ) projection optical machine.

At present, with the continuous development of AR technology, the requirements for AR projection lenses are also continuously improved, and the requirements for light weight and miniaturization of AR projection optical machine imaging lenses are also more and more strict. Because of the limitation of the mass production technology level and lower reliability, the existing projection lens is difficult to meet the requirements.

Disclosure of Invention

The purpose of the present disclosure is to provide a projection lens and a projection apparatus, which can reduce cost of mass production while improving reliability.

An embodiment of a first aspect of the present disclosure provides a projection lens including a lens group having positive optical power;

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

According to some embodiments of the disclosure, the projection lens further comprises a stop; the diaphragm is arranged on the image side of the lens group.

According to some embodiments of the disclosure, the lens group includes three aspherical lenses and one spherical lens.

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

According to some embodiments of the disclosure, the first lens is an aspherical lens, the second lens is an aspherical lens, the third lens is an aspherical lens, and the fourth lens is a spherical lens.

According to some embodiments of the disclosure, the first lens is a plastic lens, the second lens is a plastic lens, the third lens is a plastic lens, and the fourth lens is a glass lens.

According to some embodiments of the present disclosure, the projection lens satisfies:

3mm < f <9mm; where f is the total effective focal length of the projection lens.

According to some embodiments of the present disclosure, the projection lens satisfies:

1mm<f1<8mm；-8mm<f2<-1mm；-50mm<f3<-5mm；1mm<f4<8mm；

wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

According to some embodiments of the present disclosure, the projection lens satisfies:

0.05＜T4/TTL＜0.4；

wherein TTL is the total optical length of the projection lens, and T4 is the center thickness of the fourth lens.

According to some embodiments of the present disclosure, the projection lens satisfies:

0.01≤Air2/TTL＜0.5；

wherein Air2 is the Air space behind the second lens.

According to some embodiments of the present disclosure, the projection lens satisfies:

1＜R3＜5，0.5＜R4＜5；

wherein R3 and R4 are the curvature radiuses of the two surfaces of the second lens.

Embodiments of a second aspect of the present disclosure provide a projection apparatus comprising a projection lens as described in the first aspect.

In the projection lens and the projection device provided by the disclosure, the projection lens comprises a lens group, wherein the lens group has positive focal power; the lens group sequentially comprises a first lens, a second lens, a third lens and a fourth lens from an image space to an object space, and the focal power is sequentially set to be positive, negative and positive. The projection light of the image source sequentially passes through each lens in the lens group to form an image in the image space, and the projection lens of the image source only uses four lenses, so that the number of the lenses is small, the production cost and the assembly difficulty can be reduced, and the reliability of the projection lens can be improved.

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 designate like parts throughout the figures. In the drawings:

FIG. 1 is a schematic view of a projection lens I provided by the present disclosure;

FIG. 2 shows an optical path diagram of a projection lens I;

FIG. 3 shows an optical distortion diagram of projection lens one;

FIG. 4 shows a MTF diagram for projection lens one;

FIG. 5 is a defocus MTF diagram showing projection lens one;

FIG. 6 is a graph showing the relative illuminance of projection lens one;

fig. 7 is a schematic view of a projection lens ii provided by the present disclosure;

fig. 8 shows an optical path diagram of a projection lens two;

FIG. 9 shows an optical distortion diagram of a projection lens II;

FIG. 10 shows a MTF diagram for projection lens two;

fig. 11 is a defocus MTF diagram showing a projection lens two;

fig. 12 is a view showing the relative illuminance of the second projection lens.

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 only exemplary and is not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.

It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present utility model are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In addition, the technical solutions of the embodiments of the present utility model may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present utility model.

FIG. 1 illustrates a schematic diagram of a projection lens provided by the present disclosure; as shown in fig. 1, the projection lens provided in the present disclosure includes, in order from an image space to an object space, a diaphragm, a lens group, and an image source, and in some embodiments, a turning prism (not shown in fig. 1) may be further disposed between the lens group and the image source, where a projection light of the image source sequentially passes through the turning prism, the lens group, and the diaphragm to form an image on the image space.

Since the micro led emits light, the structure is compact, the volume is small, and the miniaturization of the projection lens is facilitated, so that the image source of the embodiment can adopt the micro led panel.

In this embodiment, the lens group includes at least three aspherical lenses and one spherical lens, and the lens group has positive optical power. Specifically, as shown in fig. 1, the lens group includes a first lens G1, a second lens G2, a third lens G3, and a fourth lens G4, which are disposed in order from the image side to the object side. In this embodiment, only 4 lenses are used, and the number of lenses is small, so that the production cost and the assembly difficulty can be reduced.

Specifically, the first lens G1 is a biconvex lens, the second lens G2 is a convex-concave lens with a concave surface facing the object, the third lens G3 is a convex-concave lens with a concave surface facing the object, and the fourth lens G4 is a biconvex lens.

Specifically, the first lens G1 is set to positive power, the second lens G2 is set to negative power, the third lens G3 is set to negative power, and the fourth lens G4 is set to positive power, so that the lens group has positive power.

Specifically, the first lens G1 is an aspheric lens, the second lens G2 is an aspheric lens, the third lens G3 is an aspheric lens, and the fourth lens G4 is a spherical lens, and it can be seen that the lens group of the embodiment includes 3 aspheric lenses, only 1 spherical lens, and the spherical lens is disposed at the rearmost end of the lens group, that is, near one end of the image source. In this embodiment, 3 aspherical lenses are used, and aberration such as chromatic aberration of the vertical axis and spherical aberration can be reduced with few lenses.

Specifically, the first lens G1 is a plastic lens, the second lens G2 is a plastic lens, the third lens G3 is a plastic lens, and the fourth lens G4 is a glass lens. In the embodiment, under the condition of maximally reducing aberration, the 3 aspheric lenses are made of plastic materials, so that the mass production cost is reduced. The last spherical lens is close to the image source, the temperature of the image source is higher (about 70-90 ℃) when the image source emits light, the thermal stability of the glass material is good, and the last spherical lens G4 is made of the glass material, so that the risk of heat deficiency and focus of the projection lens is reduced.

In addition, a protective glass can be arranged between the turning prism and the image source, the size of the protective glass is not smaller than that of the image source, and the image source can be isolated and protected through the protective glass.

Specifically, the projection lens satisfies the following conditions: 3mm < f <9mm; where f is the total effective focal length of the projection lens. Specifically, the projection lens satisfies: 1mm < f1<8mm; -8mm < f2< -1mm; -50mm < f3< -5mm;1mm < f4<8mm; wherein f1 is the focal length of the first lens G1, f2 is the focal length of the second lens G2, f3 is the focal length of the third lens G3, and f4 is the focal length of the fourth lens G4.

In this embodiment, the optical power of each lens in the projection lens is distributed uniformly, so that the tolerance sensitivity of each lens is low, the production yield of the projection lens is improved, and mass production is facilitated.

Specifically, the projection lens satisfies the following conditions: T1/TTL is more than 0.1 and less than 0.4,0.07 and less than T2/TTL is more than 0.3,0.05 and less than T3/TTL is more than 0.3,0.05 and less than T4/TTL is more than 0.4; wherein, TTL is the total optical length of the projection lens, T1 is the center thickness of the first lens G1, T2 is the center thickness of the second lens G2, T3 is the center thickness of the third lens G3, and T4 is the center thickness of the fourth lens G4. The embodiment compresses the total optical length of the projection lens to an extremely short level, which is beneficial to the miniaturization of the projection optical machine.

In the embodiment, the thickness of each lens in the projection lens is properly distributed, which is beneficial to reducing the manufacturing process difficulty of the lens, thereby being beneficial to saving raw materials and reducing the cost; the projection lens of the embodiment has small size and compact structure, and is beneficial to realizing the miniaturization of projection equipment.

Specifically, the projection lens satisfies the following conditions: air0/TTL is more than or equal to 0.01 and less than 0.1; air1/TTL less than or equal to 0.01

0.1; air2/TTL is more than or equal to 0.01 and less than 0.5; air3/TTL is more than or equal to 0.01 and less than 0.5; air4/TTL is more than or equal to 0.01 and less than 0.3; wherein Air0 is the Air space after the diaphragm, air1 is the Air space after the first lens G1, air2 is the Air space after the second lens G2, air3 is the Air space after the third lens G3, and Air4 is the Air space after the fourth lens G4.

In this embodiment, the air space behind the diaphragm and the air space behind each lens are appropriately allocated according to the total optical length of the projection lens, which is beneficial to the structural design of the projection lens, thereby facilitating the assembly and mass production of the lens. The air space behind the diaphragm is restrained, so that the AR optical machine and the waveguide sheet AA are convenient to assemble; the lens is matched with the lens barrel structure, so that the assembly is convenient, and the process assembly difficulty is reduced; the aberration of the outer edge of the shaft of the lens is reduced, so that the image quality is improved. The air gap between the fourth lens and the image source is restricted according to the above, so that the feasibility of structural design and process assembly is ensured, the length of the lens is greatly reduced, and the miniaturization and mass production of the lens are facilitated.

Specifically, the projection lens satisfies the following conditions: r1 is more than 1 and less than 5, -15 is more than 15 and R2 is more than-1; r3 is more than 1 and less than 5, R4 is more than 0.5 and less than 5; r5 is more than 1 and less than 5, R6 is more than 1 and less than 5; r7 is more than 1 and less than 7, R8 is more than-10;

wherein R1 and R2 are radii of curvature of the first lens surface, R3 and R4 are radii of curvature of the second lens surface, R5 and R6 are radii of curvature of the third lens surface, and R7 and R8 are radii of curvature of the fourth lens surface.

In the embodiment, the curvature radius of each lens in the projection lens is properly set, which is beneficial to reducing the manufacturing process difficulty of the lens; the tolerance sensitivity of the lens is reduced, and the yield of lens assembly is improved.

The projection lens provided in this embodiment can realize the following functions based on the above structural design constraint:

the angle of view is more than or equal to 0 degree and less than or equal to 40 degrees, the image height is more than or equal to 0 degree and less than or equal to 5mm, the matching resolution is less than or equal to 17 cycles/deviee (corresponding to less than or equal to 155 lp/mm), and the single-wavelength LED light source is more suitable for single-wavelength LED light sources.

In the present application, the aspherical surface shape equation adopted by the aspherical optical lens is:

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

c is the curvature of the aspherical apex, K is the quadric coefficient, A ₁ ，A ₂ ，A ₃ ，A ₄ ，A ₅ ，A _n Is high enough toThe order aspherical coefficient, Z, is the offset in the optical axis direction, and r is the aspherical height, i.e., the height from the center of the lens to the edge of the lens.

Based on the above structural design constraints, the present application provides two specific projection lenses as follows.

As shown in fig. 1, the projection lens provided in the embodiment of the application has an optical total length of 7.4mm, and the image source adopts a 0.13 inch micro led panel, and the optical design basic parameters of each lens in the embodiment are shown in table 1, wherein the parameters include the curvature radius, thickness, glass material, half caliber and the like of the lens.

Fig. 2 shows an optical path diagram of a projection lens one, which adopts a reverse optical path design.

Fig. 3 shows an optical distortion diagram of the first projection lens, from which it can be seen that the optical distortion of the first projection lens is < 1.5% and meets the viewing level of the human eye.

Fig. 4 shows the MTF plot for projection lens one, from which it can be seen that the average MTF for each field of view is > 0.6, indicating good imaging.

TABLE 1

The main parameters of the projection lens are as follows: view angle = 30 °; entrance pupil diameter = 4mm; total effective focal length f=5.85 mm.

Fig. 5 is a view showing the out-of-focus MTF of the projection lens one, in which the out-of-focus range of MTF > 0.3 is greater than 0.026mm, and it can be seen that the projection lens one has a large out-of-focus range, has a low risk of thermal deficiency and can be adapted to an unstable lighting environment.

Fig. 6 is a graph showing the relative illuminance of the first projection lens, wherein the illuminance of the outermost edge of the graph is greater than 78% relative to the center, and the graph shows that the first projection lens has uniform brightness of an imaging picture, less edge loss light energy and high illumination light utilization rate.

As shown in fig. 7, the projection lens two provided in the embodiment of the application has an optical total length of 7.4mm, and the image source adopts a 0.13 inch micro led panel, and the optical design basic parameters of each lens in the embodiment are shown in table 2, wherein the parameters include the radius of curvature, thickness, glass material, half caliber and the like of the lens.

TABLE 2

The two main parameters of the projection lens are as follows: view angle = 30 °; entrance pupil diameter = 4mm; total effective focal length f=5.85 mm.

Fig. 8 shows a light path diagram of a projection lens two, which adopts a reverse light path design.

Fig. 9 shows an optical distortion diagram of the second projection lens, from which it can be seen that the optical distortion of the second projection lens is < 1.5%, satisfying the human eye viewing level.

Fig. 10 shows the MTF plot for projection lens two, from which it can be seen that the average MTF for each field of view is > 0.6, indicating good imaging.

Fig. 11 is a view showing the defocus MTF of the projection lens two, in which the defocus range of MTF > 0.3 is greater than 0.02mm, and the projection lens two has a large defocus range, is low in risk of thermal deficiency and can be adapted to an unstable lighting environment.

Fig. 12 is a graph showing the relative illuminance of the second projection lens, wherein the illuminance of the outermost edge of the second projection lens relative to the center is more than 79%, which shows that the brightness of the second imaging image of the second projection lens is uniform, the edge loss light energy is less, and the illumination light utilization rate is high.

In the projection lens provided by the disclosure, the projection lens sequentially comprises a diaphragm, a lens group and an image source from an image space to an object space, wherein the lens group at least comprises three aspheric lenses and one spherical lens, and the lens group has positive focal power. The projection light of the image source sequentially passes through the lens group and the diaphragm to form an image, and as more aspheric lenses are used in the projection lens, the cost of mass production is reduced, and the aberration is reduced to the maximum extent; a spherical lens is reserved, so that the phenomenon of heat deficiency and focus is prevented, and the reliability of the projection lens can be improved.

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

The embodiments of the present disclosure are 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 made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.

Claims (12)

1. A projection lens, wherein the projection lens comprises a lens group, the lens group having positive optical power;

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

2. The projection lens of claim 1, further comprising a stop; the diaphragm is arranged on the image side of the lens group.

3. The projection lens of claim 1 wherein the lens group comprises three aspherical lenses and one spherical lens.

4. The projection lens of claim 1 wherein the first lens is a biconvex lens, the second lens is a convex-concave lens with a concave surface facing the object, the third lens is a convex-concave lens with a concave surface facing the object, and the fourth lens is a biconvex lens.

5. The projection lens of claim 3 wherein the first lens is an aspherical lens, the second lens is an aspherical lens, the third lens is an aspherical lens, and the fourth lens is a spherical lens.

6. The projection lens of claim 5 wherein the first lens is a plastic lens, the second lens is a plastic lens, the third lens is a plastic lens, and the fourth lens is a glass lens.

7. The projection lens of claim 4, wherein the projection lens satisfies:

3mm < f <9mm; where f is the total effective focal length of the projection lens.

8. The projection lens of claim 7, wherein the projection lens satisfies:

1mm<f1<8mm；-8mm<f2<-1mm；-50mm<f3<-5mm；1mm<f4<8mm；

wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

9. The projection lens of claim 4, wherein the projection lens satisfies:

0.05＜T4/TTL＜0.4；

wherein TTL is the total optical length of the projection lens, and T4 is the center thickness of the fourth lens.

10. The projection lens of claim 9, wherein the projection lens satisfies:

0.01≤Air2/TTL＜0.5；

wherein Air2 is the Air space behind the second lens.

11. The projection lens of claim 4, wherein the projection lens satisfies:

1＜R3＜5，0.5＜R4＜5；

wherein R3 and R4 are the curvature radiuses of the two surfaces of the second lens.

12. A projection device, characterized in that it comprises a projection lens according to any of claims 1 to 11.

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