CN215910780U

CN215910780U - Ultra-short-focus projection optical system and projection equipment

Info

Publication number: CN215910780U
Application number: CN202121786640.1U
Authority: CN
Inventors: 李源财; 全丽伟; 李守林; 王浩
Original assignee: Union Optech Co Ltd
Current assignee: Union Optech Co Ltd
Priority date: 2021-08-02
Filing date: 2021-08-02
Publication date: 2022-02-25
Anticipated expiration: 2031-08-02

Abstract

The utility model discloses an ultra-short focus projection optical system which comprises a display unit, a first lens group with positive focal power, a second lens group with positive focal power, a third lens group with negative focal power and an aspheric reflector which are sequentially arranged along a projection direction, wherein the first lens group comprises a first lens, a second lens and a diaphragm which are sequentially arranged along the projection direction, the first lens is a glass aspheric lens, the second lens is a glass spherical lens, and the first lens and the second lens are respectively bent towards the diaphragm gradually from the center to the periphery of the first lens and the second lens. The ultra-short-focus projection optical system and the projection equipment provided by the utility model can meet the requirement of large aperture and have the advantage of high resolution.

Description

Ultra-short-focus projection optical system and projection equipment

Technical Field

The utility model relates to the technical field of projection equipment, in particular to an ultra-short-focus projection optical system and projection equipment.

Background

In recent years, with the development of projection technology, projection apparatuses have been widely used in the fields of home use, education, office work, and the like, and among them, ultra-short-focus projectors are favored for projecting a large screen at a short distance and making better use of the projection apparatuses in a compact space environment. As a core component in an ultra-short-focus projector, an ultra-short-focus projection optical system is expensive, and in order to reduce cost, an aperture value of an existing ultra-short-focus projection optical system is generally more than 2.5, and an aperture is small.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide an ultra-short-focus projection optical system and projection equipment, and aims to solve the problem that the conventional ultra-short-focus projection optical system is small in aperture.

In order to achieve the above object, the ultra-short focus projection optical system provided by the present invention includes a display unit, a first lens group having positive focal power, a second lens group having positive focal power, a third lens group having negative focal power, and an aspheric mirror, which are sequentially disposed along a projection direction;

wherein, first lens group includes the edge first lens, second lens and the diaphragm that the direction of projection set gradually, first lens are glass aspheric surface lens, the second lens are glass spherical surface lens, just first lens with the second lens is from its center to its periphery respectively and is gradually towards the direction of diaphragm is crooked.

Optionally, the second lens group and the third lens group may be movably disposed close to and away from the display unit along the projection direction.

Optionally, the lens system further comprises a linkage, wherein the linkage connects the second lens group and the third lens group respectively.

Optionally, the second lens group includes a third lens, and the third lens is a plastic aspheric lens.

Optionally, the focal power of the first lens group is set to phi₁，0.04≤φ₁≤0.06；

Setting the focal power of the second lens group to be phi₂，0≤φ₂≤0.01；

Setting the focal power of the third lens group to phi₃，-0.04≤φ₃≤0；

Setting the focal power of the aspheric reflector to phi₄，0.06≤φ₄≤0.09。

Optionally, the third lens group includes a fourth lens and a fifth lens that are sequentially disposed along the projection direction, and the fourth lens and the fifth lens are plastic aspheric lenses.

Optionally, the focal power of the fourth lens is greater than or equal to-0.05 and less than or equal to 0;

and the focal power of the fifth lens is more than or equal to 0 and less than or equal to 0.04.

Optionally, an optical axis is formed in the ultra-short focus projection optical system;

the display unit comprises a digital micromirror device, the offset of the center of the digital micromirror device and the optical axis is C, and C is larger than or equal to 2.6mm and smaller than or equal to 3 mm.

Optionally, the first lens group further comprises a cemented lens located on a side of the first lens away from the second lens, the cemented lens comprising a sixth lens and a seventh lens that are cemented together.

The utility model also provides projection equipment which comprises the ultra-short-focus projection optical system, wherein the ultra-short-focus projection optical system comprises a display unit, a first lens group with positive focal power, a second lens group with positive focal power, a third lens group with negative focal power and an aspheric reflector which are sequentially arranged along the projection direction;

In the technical scheme of the utility model, projection light rays are transmitted through the first lens group with positive focal power, the second lens group with positive focal power and the third lens group with negative focal power in sequence, meanwhile, the first lens of the glass aspheric lens is matched with the second lens of the glass spherical lens, and the first lens and the second lens are respectively bent from the center to the periphery thereof in a direction gradually facing the diaphragm, so that spherical aberration and coma aberration generated by the diaphragm are effectively corrected, the height of the light rays of the rear group is improved, and the high-resolution high-aperture high-power liquid crystal display has the advantage of high resolution under the requirement of realizing a large aperture.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic diagram of an ultra-short-focus projection optical system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a projection optical path of the ultra-short-focus projection optical system shown in FIG. 1;

fig. 3 is a schematic mirror view of each lens of the ultra-short-focus projection optical system in fig. 1.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				100	Ultra-short focus projection optical system	27	Twelfth lens element
1	Display unit	3	Second lens group
				11	DMD chip	31	Third lens
12	Equivalent prism	4	Third lens group
				2	First lens group	41	Fourth lens
21	First lens	42	Fifth lens element
				22	Second lens	43	Eighth lens element
23	Diaphragm	44	Ninth lens
				24	Sixth lens element	45	Tenth lens
25	Seventh lens element	5	Non-spherical reflector
				26	Eleventh lens

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is 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 addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

In view of this, the present invention provides an ultra-short-focus projection optical system, and fig. 1 to 3 are embodiments of the ultra-short-focus projection optical system provided in the present invention.

Referring to fig. 1 and 2, the ultra-short-focus projection optical system 100 includes a display unit 1, a first lens group 2 having positive focal power, a second lens group 3 having positive focal power, a third lens group 4 having negative focal power, and an aspheric mirror 5, which are sequentially disposed along a projection direction, wherein the first lens group 2 includes a first lens 21, a second lens 22, and a stop 23, which are sequentially disposed along the projection direction, the first lens 21 is a glass aspheric lens, the second lens 22 is a glass spherical lens, and the first lens 21 and the second lens 22 are respectively curved from the center to the periphery thereof in a direction gradually facing the stop 23.

In the technical scheme of the utility model, projection light is transmitted through the first lens group 2 with positive focal power, the second lens group 3 with positive focal power and the third lens group 4 with negative focal power in sequence, meanwhile, the first lens 21 of the glass aspheric lens is matched with the second lens 22 of the glass spherical lens, and the first lens 21 and the second lens 22 are respectively bent from the center to the periphery thereof in a direction gradually towards the diaphragm 23, so that spherical aberration and coma aberration generated by the diaphragm 23 are effectively corrected, the height of the light of the rear group is improved, and the high-resolution advantage is achieved under the requirement of realizing a large aperture.

It is emphasized that the present invention does not limit the specific degree of curvature of the first lens 21 and the second lens 22, as long as effective correction of spherical aberration and coma generated by the diaphragm 23 can be achieved. Specifically, referring to fig. 1, in the present embodiment, the curvature of the light-emitting surface (the side close to the aspheric reflector 5) of the first lens 21 is greater than the curvature of the light-entering surface (the side close to the display unit 1), and the curvature of the light-entering surface of the second lens 22 is greater than the curvature of the light-emitting surface.

It will be appreciated that the optical power is equal to the difference between the image-side and object-side beam convergence, which characterizes the ability of the optical element to deflect light. When the focal power is positive, the refraction of the light is convergent; when the focal power is negative, the refraction of the light is divergent. The optical power can be suitable for representing a certain refractive surface of a lens (namely, a surface of the lens), can be suitable for representing a certain lens, and can also be suitable for representing a system (namely a lens group) formed by a plurality of lenses together.

Further, the second lens group 3 and the third lens group 4 are both movable close to and away from the display unit 1 along the projection direction, and the focusing of the ultra-short-focus projection optical system 100 is realized through the movement of the second lens group 3 and the third lens group 4, which is helpful for improving the optical performance of the ultra-short-focus projection optical system 100.

It should be noted that the present invention is not limited to the specific moving manner of the second lens group 3 and the third lens group 4, and the second lens group 3 and the third lens group 4 may move independently, or the second lens group 3 and the third lens group 4 may be provided in a linked manner. Specifically, referring to fig. 1, in the present embodiment, the ultra-short-focus projection optical system 100 further includes a linkage member (not shown in the figure), where the linkage member is respectively connected to the second lens group 3 and the third lens group 4, and the linkage member drives the second lens group 3 and the third lens group 4 to adjust positions according to a certain proportional relationship, so as to implement linkage focusing, and implement distortion and image resolution correction of different images in 70 inches to 120 inches by linkage focusing.

The present invention does not limit the specific implementation of the linkage member, and may be a screw rod structure or a gear structure, or other structures for realizing the linkage of the second lens group 3 and the third lens group 4, which are not described herein again.

In addition, the second lens group 3 includes a third lens 31, the third lens 31 is a plastic aspheric lens, and is linked with the third lens group 4, so as to further improve the effect of correcting distortion and image resolution of different image sizes from 70 inches to 120 inches.

Further, the focal power of the first lens group 2 is set to be phi₁，0.04≤φ₁Less than or equal to 0.06; setting the focal power of the second lens group 3 to phi₂，0≤φ₂Less than or equal to 0.01; setting the focal power of the third lens group 4 to phi₃，-0.04≤φ₃Less than or equal to 0; setting the aspherical surfaceThe focal power of the reflector 5 is phi₄，0.06≤φ₄Less than or equal to 0.09. When the lens group is distributed according to the optical focal length, the projection ratio is less than 0.2, and the high temperature is not virtual focus. Meanwhile, the sensitivity of each lens group is greatly reduced, and mass production is facilitated.

Moreover, the third lens group 4 includes a fourth lens 41 and a fifth lens 42 sequentially arranged along the projection direction, and the fourth lens 41 and the fifth lens 42 are plastic aspheric lenses, so that the incident angle of light can be effectively corrected, and the volume and cost of the lens can be reduced.

Furthermore, the focal power of the fourth lens 41 is greater than or equal to-0.05 and less than or equal to 0, and the focal power of the fifth lens 42 is greater than or equal to 0 and less than or equal to 0.04, so that the lens can be automatically balanced in a high-temperature state by matching the focal powers of the fourth lens 41 and the fifth lens 42, and the high-temperature non-virtual focus is realized.

The third lens group 4 further includes an eighth lens 43, a ninth lens 44, and a tenth lens 45, which are sequentially disposed along the projection direction, the eighth lens 43, the ninth lens 44, and the tenth lens 45 are all located between the fourth lens 41 and the second lens group 3, the eighth lens 43, the ninth lens 44, and the tenth lens 45 are all glass spherical lenses, the focal power of the eighth lens 43 and the focal power of the tenth lens 45 are all equal to or greater than 0 and equal to or less than 0.04, and the focal power of the ninth lens 44 is equal to or greater than-0.05 and equal to or less than 0.

An optical axis is formed in the ultra-short-focus projection optical system 100, the display unit 1 comprises a digital micro-mirror device, the offset between the center of the digital micro-mirror device and the optical axis is C, and C is not less than 2.6mm and not more than 3 mm. Thus, the imaging definition is favorably improved. Specifically, referring to fig. 1, in the present embodiment, the digital Micromirror device is a DMD (digital Micromirror device) chip, a deviation between the center of the DMD chip 11 and the optical axis is 2.8mm, the DMD chip 11 is 0.33 inch, the resolution is 1368 × 768, and 1080P can be realized by a galvanometer.

The display unit 1 further comprises an equivalent prism 12, and the equivalent prism 12 is disposed between the DMD chip 11 and the first lens group 2, so as to reduce aberration formed by refraction and transmission of light.

The first lens group 2 further includes a cemented lens on a side of the first lens 21 remote from the second lens 22, the cemented lens including a sixth lens 24 and a seventh lens 25 that are cemented together, and thus, helps eliminate chromatic aberration. It can be understood that the light passing through the lens forms chromatic aberration, so that the image is blurred, and therefore the chromatic aberration becomes a serious defect of the lens image, the cemented lens is formed by cementing a plurality of lenses together, the chromatic aberration is generated after the light passes through one lens of the cemented lens and is opposite to the chromatic aberration generated when the refracted light continues to pass through the other lens, and the chromatic aberration can be offset with the chromatic aberration generated before, so that the purpose of eliminating the chromatic aberration is achieved.

Specifically, the gluing connection between the sixth lens 24 and the seventh lens 25 is realized by optical glue, and the optical glue has high light transmittance, which is beneficial to improving the imaging effect of the projected light.

The first lens group 2 further includes an eleventh lens 26 and a twelfth lens 27 that are sequentially disposed along the projection direction, the eleventh lens 26 and the twelfth lens 27 are both located between the sixth lens 24 and the display unit 1, the eleventh lens 26 and the twelfth lens 27 are both glass spherical lenses, and both the focal power of the eleventh lens 26 and the focal power of the twelfth lens 27 are greater than or equal to 0 and less than or equal to 0.04.

The aspherical surface shapes of the first lens 21, the third lens 31, the fourth lens 41, the fifth lens 42, and the aspherical mirror 5 satisfy the equation:

in the above equation, the parameter c is the curvature corresponding to the radius, y is the radial coordinate, the unit of which is the same as the unit of the lens length, and k is the coefficient of the conic section; when the k coefficient is less than-1, the surface-shaped curve of the lens is a hyperbola; when the k coefficient is equal to-1, the surface-shaped curve of the lens is a parabola; when the k coefficient is between-1 and 0, the surface-shaped curve of the lens is an ellipse, when the k coefficient is equal to 0, the surface-shaped curve of the lens is a circle, and when the k coefficient is more than 0, the surface-shaped curve of the lens is an oblate; a1 to a8 each indicate a coefficient corresponding to each radial coordinate.

The following is the actual design parameters of the ultra-short-focus projection optical system 100 with F1.8 and a projection ratio of 0.2, and refer to table 1.

TABLE 1 parameters of the ultra-short-Focus projection optical System 100

Wherein, OBJ is the object plane, IMA is the image plane, S26 is the light-emitting plane of the equivalent prism 12, S27 is the light-entering plane of the equivalent prism 12, S1 to S25 are the mirror surfaces of the lenses, respectively, and reference is made to fig. 3 for concrete reference of S1 to S25.

Furthermore, the S1 coefficients are:

k：-768；

a1：0；

a20.00011485935；

a3：-5.3053334e-007；

a4：2.126744e-009；

a5：-5.4787393e-012；

a6：8.0470803e-015；

a7：-4.9662071e-018。

the coefficient of S2 is:

k：-565.9319；

a1：0；

a2：-4.6842153e-006；

a3：1.3583932e-008；

a4：2.96366079486753e-012；

a5：2.35668648024052e-015；

a6：-1.7709563837241e-019；

a7：-6.05918030192083e-022。

the coefficient of S3 is:

k：-565.9319；

a1：0；

a2：-4.6842153e-006；

a3：1.3583932e-008；

a4：2.96366079486753e-012；

a5：2.35668648024052e-015；

a6：-1.7709563837241e-019；

a7：-6.05918030192083e-022。

the coefficient of S4 is:

k：-0.4040741；

a1：0；

a2：4.90490480030574e-007；

a3：-2.05760498407608e-010；

a4：2.99679825125034e-014；

a5：5.55711304020551e-018；

a6：-2.86845642405709e-021；

a7：2.91053534222281e-025。

the coefficient of S5 is:

k：90.3686；

a1：0；

a2：3.37355419190151e-008；

a3：-1.68426620586378e-010；

a4：-1.77578855135222e-011；

a5：1.31858269908392e-013；

a6：1.61679421023673e-016；

a7：-3.13849187032395e-018。

the coefficient of S12 is:

k：-1.3840751；

a1：0；

a2：-2.79361010729748e-008；

a3：-6.6497057344366e-010；

a4：-2.54430577284334e-013；

a5：-1.84664483140541e-015；

a6：6.46082131490784e-017；

a7：-1.54392143969012e-019。

the coefficient of S13 is:

k：-25.2567；

a1：0；

a2：4.90490480030574e-007；

a3：-3.94843412007971e-010；

a4：3.02112629843759e-013；

a5：1.40840432176276e-015；

a6：6.90569325719901e-019；

a7：-6.52550386131808e-021。

the coefficient of S18 is:

k：-12.457；

a1：0；

a2：4.904900574e-007；

a3：-2.05760908e-010；

a4：2.99679824e-014；

a5：-7.4255518e-16；

a6：1.3859057e-18；

a7：1.8118184e-23。

the coefficient of S19 is:

k：-1.4040741；

a1：0；

a2：-5.2362612e-06；

a3：-2.057608e-010；

a4：2.9244063e-09；

a5：5.5046807e-16；

a6：5.5046807e-16；

a7：4.8296771e-18。

according to the utility model, 3 plastic aspheric lenses (the third lens 31, the fourth lens 41 and the fifth lens 42) are adopted, so that the projection ratio is below 0.20, and the aperture is 1.8, so that the requirements of high resolution and high brightness are met under the condition of ensuring low cost; by reasonably distributing the focal power of the lenses, the ultra-short-focus projection optical system 100 can balance the focal distances of the lenses in a high-temperature state under the condition that 3 plastic aspheric lenses are adopted, so that the high-temperature state is free of virtual focus; by reasonable lens structure layout, the second lens group 3 and the third lens group 4 can correct curvature of field and distortion under different projection sizes, and the projected picture can still maintain high resolution between 70 inches and 120 inches.

The utility model further provides a projection device, which includes the ultra-short-focus projection optical system 100, and the projection device includes all technical features of the ultra-short-focus projection optical system 100, so that the projection device also has technical effects brought by all the technical features, and details are not repeated here.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. An ultra-short-focus projection optical system is characterized by comprising a display unit, a first lens group with positive focal power, a second lens group with positive focal power, a third lens group with negative focal power and an aspheric mirror which are sequentially arranged along a projection direction;

2. The ultra-short focus projection optical system as claimed in claim 1, wherein the second lens group and the third lens group are movably disposed close to and away from the display unit in the projection direction.

3. The ultra-short focus projection optical system of claim 2, further comprising a linkage connecting the second lens group and the third lens group, respectively.

4. The ultra-short focus projection optical system of claim 3, wherein the second lens group comprises a third lens, and the third lens is a plastic aspheric lens.

5. The ultra-short focus projection optical system of claim 1, wherein the first lens group is set to have an optical power of Φ₁，0.04≤φ₁≤0.06；

6. The ultra-short-focus projection optical system as claimed in claim 1, wherein the third lens group comprises a fourth lens and a fifth lens sequentially arranged along the projection direction, and the fourth lens and the fifth lens are plastic aspheric lenses.

7. The ultra-short focus projection optical system as claimed in claim 6, wherein an optical power of said fourth lens is equal to or greater than-0.05 and equal to or less than 0;

8. The ultra-short focus projection optical system of claim 1, wherein an optical axis is formed inside the ultra-short focus projection optical system;

9. The ultra-short focus projection optical system of claim 1, wherein the first lens group further comprises a cemented lens on a side of the first lens remote from the second lens, the cemented lens comprising a sixth lens and a seventh lens that are cemented together.

10. A projection apparatus comprising the ultra-short-focus projection optical system as set forth in any one of claims 1 to 9.