CN114660775B

CN114660775B - Low-distortion full-high-definition projection lens

Info

Publication number: CN114660775B
Application number: CN202210318279.2A
Authority: CN
Inventors: 聂晓宇
Original assignee: Shanghai Shengxiang Industrial Testing Technology Co ltd
Current assignee: Shanghai Shengxiang Industrial Testing Technology Co ltd
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2022-11-11
Anticipated expiration: 2042-03-29
Also published as: CN114660775A

Abstract

The invention discloses a low-distortion full-high-definition projection lens, which at least comprises: the first focusing lens group has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the first focusing lens group is f01; a diaphragm; the second converging lens group has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the second converging lens group is f02; a display chip; the first converging lens group, the diaphragm, the second converging lens group and the display chip are sequentially arranged from the projection side to the imaging side, the total length of the projection lens is less than 30mm, the maximum aperture is less than 14mm, and the rear intercept is greater than 14.5mm; the difference between f01 and f02 is less than 1. The invention has good imaging effect, high resolution and small distortion, the total lens length TTL is less than 30mm, the maximum aperture of the lens is less than 14mm, and the back intercept BFL is more than 14.5mm; low cost, high thermal stability, easy processing and simple assembly.

Description

Low-distortion full-high-definition projection lens

Technical Field

The invention belongs to the field of photoelectric industry and the field of industrial detection of machine vision, and particularly relates to a low-distortion full-high-definition projection lens.

Background

With the rapid development of semiconductor technology and the continuous progress of projection display technology, projection devices are also gradually applied to the fields of household, business, education and industrial detection. The LCOS technology and the DLP technology are widely used, and the DLP technology has become one of the mainstream projection devices due to its high definition picture, high brightness image, rich colors and high contrast display.

The DLP technology is mainly characterized in that the chip is provided with uniformly distributed micro mirrors, and the micro mirrors can rotate at a certain angle, so that the light path of the illumination system is reflected into the projection lens. The illumination system in the DLP technology is divided into a telecentric structure and a non-telecentric structure, the incident angle of the illumination system incident to the DMD surface must be matched with the rotation angle of the DMD, the homogeneity of a projection picture is improved by adopting a telecentric light path structure, an imaging light beam and an illumination light beam are generally separated by a TIR prism or an RTIR prism, and the structure of the whole system is more compact.

In the projection lens design process, the aberration is balanced, the F number is selected, the distortion is the difficult factor of designing, and make projection lens's F number great because illuminating beam's restriction, thereby make projection lens hardly do for a short time, and when matching in order to make projection lens and RTIR prism, need keep longer back working distance, make projection lens's the design degree of difficulty increase, consequently, it is high to design out the imaging quality hardly, the lens compact structure, the little and small projection lens of volume of distortion.

In some existing projection lens technologies, the imaging quality of an optical system is generally improved by adopting an aspheric surface technology, so that the design difficulty of the optical system can be reduced, and the system structure is simplified, but the aspheric surface technology is high in processing cost and difficult to assemble, which can increase the cost and reduce the production efficiency, for example, in patent CN103246047, a meniscus single-sided even aspheric surface is adopted, which increases the processing and assembling difficulty; secondly, the number of lenses can be increased in the system to meet the requirement of imaging quality, but the more the number of lenses is, the higher the cost is, the harder the aberration balance is, and the more the lenses are, the longer the lens length is, the miniaturization cannot be achieved, and the integration is not facilitated.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the low-distortion full-high-definition projection lens which is small in size, high in imaging quality, low in processing cost and small in distortion.

The technical scheme adopted by the invention for solving the technical problem is as follows: a low distortion full high definition projection lens, comprising at least:

the first converging lens group has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the first converging lens group is f01;

a diaphragm;

the second converging lens group has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the second converging lens group is f02;

a display chip;

the first converging lens group, the diaphragm, the second converging lens group and the display chip are sequentially arranged from the projection side to the imaging side, the total length of the projection lens is less than 30mm, the maximum aperture is less than 14mm, and the rear intercept is greater than 14.5mm;

the difference between f01 and f02 is less than 1.

The difference value of the focal lengths of the first converging lens group and the second converging lens group is small, the aberration born by the first converging lens group and the second converging lens group is balanced, and the structure is more stable.

Further, the first converging lens group focal lengths 15mm < -01 < -16mm, the second converging lens group focal lengths 15mm < -02 < -16mm, and 1< -01/f 02<1.1.

Further, the first focusing lens group comprises four lenses, which are, in order from the projection side to the imaging side, a first biconvex lens with positive focal power, a second biconcave lens with negative focal power, a third biconcave lens with negative focal power and a fourth biconvex lens with positive focal power.

Further, the focal length of the first biconvex lens is 12mm or < -1 > or < -19mm, the focal length of the second biconcave lens is-10mm or less and is used for covering f2< -6mm, the focal length of the third biconcave lens is-60mm or less and is used for covering f3< -140mm, and the focal length of the fourth biconvex lens is 8mm or less and is used for covering f4 or less and is used for covering 13mm.

The first biconvex lens is combined with the second biconcave lens with negative focal power at the same time of converging the light ray angle, so that spherical aberration and astigmatism are eliminated, and coma and curvature of field are eliminated by the alternating arrangement of the third biconcave lens and the fourth biconvex lens.

Furthermore, the second converging lens group comprises five lenses, and the fifth meniscus thick lens with negative focal power, the sixth biconcave lens with negative focal power, the seventh meniscus lens with positive focal power, the eighth biconvex lens with positive focal power and the ninth biconvex lens with positive focal power are sequentially arranged from the projection side to the imaging side.

Further, the focal length of the fifth meniscus thick lens is-35mm < -5 < -25mm, the focal length of the sixth biconcave lens is-12mm < -6 < -16mm, the focal length of the seventh meniscus lens is 22mm < -f7 < -32mm, the focal length of the eighth biconvex lens is 25mm < -8 < -35mm, and the focal length of the ninth biconvex lens is 2mm < -f9 < -26mm.

The fifth meniscus thick lens with negative focal power, the sixth biconcave lens with negative focal power contribute to elimination of coma, distortion and curvature of field, the seventh meniscus lens with positive focal power contributes to elimination of distortion, astigmatism and curvature of field, and the eighth biconvex lens and the ninth biconvex lens with positive focal power contribute to elimination of distortion, spherical aberration, coma and astigmatism.

Further, the effective focal length of the projection lens is f, and 1.3 is less than or equal to f01/f <1.5, and 1.3 is less than or equal to f02/f <1.5.

Furthermore, the projection lens adopts a telecentric structure and an image space telecentric light path, and the telecentricity CRA is less than 0.1 degree.

An image space telecentric light path is adopted, and the telecentricity is less than 0.1 degree, so that the uniformity of a projection picture of the projection lens is higher.

Furthermore, the spherical lenses of the first converging lens group and the second converging lens group are glass lenses, and the transmittance is greater than 95%. The global environment-friendly glass lens is adopted, the processing cost is low, the assembly is simple, the thermal stability is high, and the method is suitable for batch production.

Further, the total length of the projection lens is TTL, the effective focal length of the projection lens is f, then 2.7 case once TTL/f <2.8, the rear intercept of the projection lens is BFL, then 1.3 case once BFL/f <1.4.

Further, the ratio of the distortion theta1 of the first converging lens group to the focal length is 0.15% < theta1/f01<0.2%, and the ratio of the distortion theta2 of the second converging lens group to the focal length is-0.12% < theta2/f02<0.2%.

Further, the working distance WD =70-400mm of the projection lens.

Further, F/# =2-2.8, tr =0.65-1.05, fov =30-50 degrees for the projection lens.

The projection lens of the invention is different from other projection lenses in that a reverse distance structure is adopted (namely, the front group is negative focal power, and the rear group is positive focal power), on the premise of having longer rear intercept, a structure that the front group and the rear group are both positive focal power is adopted, the physical design difficulty is overcome, the miniaturization (TTL <30mm, BFL >14.5mm, and the maximum aperture D <14 mm) of the miniature projection lens is realized while high imaging quality (part of the field of view is close to the diffraction limit) and low distortion (DIST < 0.07%) are met, the imaging quality is higher than that of a common reverse distance projection lens, the distortion coefficient is lower than that of the reverse distance projection lens, and the processing and assembly cost is lower than that of the reverse distance projection lens by adopting a full glass spherical surface, so that the invention is suitable for batch production.

The invention has the beneficial effects that: 1) The imaging effect is good, the resolution is as high as 93lp/mm, the optical transfer functions of partial fields of view reach the diffraction limit while the resolution reaches 93lp/mm, the resolution of the existing common lens is 55lp/mm-66lp/mm, and the optical transfer functions do not reach the diffraction limit; 2) Distortion is less than 0.07%, total lens length TTL is less than 30mm, maximum aperture of the lens is less than 14mm, and back intercept BFL is greater than 14.5mm; 3) And the global environment-friendly glass lens is adopted, so that the cost is low, the thermal stability is high, the processing is easy, and the assembly is simple.

Drawings

FIG. 1 is a schematic view of the lens composition of the present invention.

FIG. 2 is a schematic view of an optical structure according to the present invention.

FIG. 3 is a diagram illustrating an optical modulation function according to a first embodiment of the present invention.

Fig. 4 is a graph of field curvature and distortion in a first embodiment of the present invention.

FIG. 5 is a diagram illustrating an optical modulation function according to a second embodiment of the present invention.

FIG. 6 is a graph of field curvature and distortion in a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an optical modulation function according to a third embodiment of the present invention.

Fig. 8 is a graph of field curvature and distortion in a third embodiment of the present invention.

FIG. 9 is a diagram of an optical modulation function according to a fourth embodiment of the present invention.

Fig. 10 is a graph of field curvature and distortion in a fourth embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, 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 obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.

A low distortion full high definition projection lens comprising:

the first converging lens group 1 has positive focal power, comprises a plurality of coaxially arranged spherical transparent lenses with the focal length of f01,

a diaphragm 3;

the second converging lens group 2 has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the second converging lens group is f02;

a display chip 4;

the first converging lens group 1, the diaphragm 3, the second converging lens group 2 and the display chip 4 are sequentially arranged from the projection side to the imaging side, the total length of the projection lens is less than 30mm, namely L is less than 30mm in figure 1, the maximum aperture is less than 14mm, namely D is less than 14mm in figure 1, and the rear intercept is more than 14.5mm.

The difference between the focal length f01 of the first converging mirror groups 1 and the focal length f02 of the second converging mirror groups 2 is less than 1, and the focal length ranges of the first converging mirror groups 1 are 15mm- (-01) and 16mm, the focal length ranges of the second converging mirror groups 2 are 15mm-02-16mm, and 1-f01/f 02<1.1.

Defining the effective focal length of the projection lens of the invention as f, 1.3-f01/f <1.5, 1.3-f02/f <1.5 and f =11-12mm, the focal length is suitable for the application in the field of industrial measurement of small visual field in cooperation with different working distances. The projection lens adopts a telecentric structure and an image space telecentric light path, the telecentric degree CRA is less than 0.1 degree, namely the included angle between the principal ray and the normal of the display chip 4 is less than 0.1 degree.

The total length of the projection lens is defined as TTL, and 2.7 & ltTTL/f & lt 2.8 & gt, namely TTL & lt 30mm, is included.

The back intercept of the projection lens is defined as BFL, and 1.3 & lt BFL/f & lt 1.4 & gt, namely BFL & gt 14.5mm.

The working distance WD =70-400mm, F/# =2-2.8, the projection ratio TR =0.65-1.05, and the FOV =30-50 degrees.

In the present embodiment, the first focusing lens group 1 includes four lenses, which are, in order from the projection side to the image side, a first biconvex lens 11 having positive optical power, a second biconcave lens 12 having negative optical power, a third biconcave lens 13 having negative optical power, and a fourth biconvex lens 14 having positive optical power; and the focal lengths of the first biconvex lenses are 12mm < -f 1< -19mm, the focal lengths of the second biconcave lenses are-10mm < -2 < -6mm, the focal lengths of the third biconcave lenses are-60mm < -f 3< -140mm, and the focal lengths of the fourth biconvex lenses are 8mm f4< -13mm. The first biconvex lens, the second biconcave lens, the third biconcave lens and the fourth biconvex lens are all spherical lenses made of glass materials, and the transmittance is more than 95%.

In the present embodiment, the second condenser lens group 2 includes five lenses, which are, in order from the projection side to the image side, a fifth meniscus thick lens 21 having negative power, a sixth biconcave lens 22 having negative power, a seventh meniscus lens 23 having positive power, an eighth biconvex lens 24 having positive power, and a ninth biconvex lens 25 having positive power; and the focal lengths of the fifth meniscus thick lenses are-35mm & lt f5 & lt-25 mm, the focal lengths of the sixth biconcave lenses are-12mm & lt f6 & lt-16 mm, the focal lengths of the seventh meniscus lenses are 22mm & lt f7 & gt 32mm, the focal lengths of the eighth biconvex lenses are 25mm & lt f8 & lt 35mm, and the focal lengths of the ninth biconvex lenses are 20mm & lt f9 & lt 26mm. The fifth meniscus thick lens, the sixth biconcave lens, the seventh meniscus lens, the eighth biconvex lens and the ninth biconvex lens are all spherical lenses made of glass materials, and the transmittance is more than 95%.

Defining the distortion of the first set of converging lenses 1 as theta1, the ratio of distortion to focal length is 0.15% < theta1/f01<0.2%.

Defining the distortion of the second set of converging lenses 2 as theta2, the ratio of distortion to focal length is-0.12% < theta2/f02<0.2%.

Example one

In the embodiment, the working distance WD of the projection lens of the invention =70mm, f/# =2.8, and the effective focal length f =11mm.

Fig. 3 is a graph of an optical transfer function MTF curve on each field image plane of the projection lens when the working distance WD =70mm, the abscissa is spatial frequency, the ordinate is OTF modulus, the full field @93lp/mm >0.68, and the curve is close to the diffraction limit, which illustrates that the imaging quality of the lens is clear. Fig. 4 is a graph of field curvature and distortion. In fig. 4, the left graph is a field curvature graph, the abscissa is a field curvature value, and the ordinate is a field angle, wherein the maximum field curvature of sagittal view is less than 0.02mm, and the maximum field curvature of meridional view is less than 0.05mm. The right graph in fig. 4 is a distortion graph with percent distortion on the abscissa and field angle on the ordinate, where maximum distortion <0.07% can be seen. The first table is a structural parameter table of the projection lens in this embodiment.

Watch 1

	Radius of curvature	Thickness (mm)	Material
				0		70
1	25.4	2	1.8，47
				2	-17.5	0.2
3	-15.5	1.1	1.6，60.2
				4	6.3	4.2
5	-90.4	1.1	1.8，47
				6	92.5	1.5
7	10.2	1.8	1.6，60.2
				8	-12.4	0.2
9		5
				10	-5.2	3.5	1.8，47
11	-9.4	0.2
				12	-20.1	1.1	1.8，24.5
13	31.2	1
				14	-31.2	1.8	1.6，57.9
15	-12.6	0.2
				16	150.4	2	1.6，60.2
17	-20.4	0.2
				18	30.1	2.3	1.6，60.2
19	-30.1	15.5

Example two

In the embodiment, the working distance WD =150mm, f/# =2.8 and the effective focal length f =11mm of the projection lens of the invention.

Fig. 5 is a graph of an optical transfer function MTF curve on each field image plane of the projection lens when the working distance WD =150mm, where the abscissa is spatial frequency, the ordinate is OTF mode value, the full field @93lp/mm >0.68, and the curve is close to the diffraction limit, which shows that the imaging quality of the lens is clear. Fig. 6 is a graph of field curvature and distortion. In fig. 6, the left graph is a field curvature graph, the abscissa is a field curvature value, and the ordinate is a field angle, wherein the maximum field curvature of sagittal view is less than 0.02mm, and the maximum field curvature of meridional view is less than 0.02mm. The right graph in fig. 6 is a distortion graph with the abscissa as the percentage of distortion and the ordinate as the field angle, where the maximum distortion <0.07% can be seen. The second table is a structural parameter table of the projection lens in this embodiment.

Watch 2

	Radius of curvature	Thickness (mm)	Material
				0		150
1	25.4	2	1.8，47
				2	-17.5	0.2
3	-15.5	1.1	1.6，60.2
				4	6.3	4.2
5	-90.4	1.1	1.8，47
				6	92.5	1.5
7	10.2	1.8	1.6，60.2
				8	-12.4	0.2
9		5
				10	-5.2	3.5	1.8，47
11	-9.4	0.2
				12	-20.1	1.1	1.8，24.5
13	31.2	1
				14	-31.2	1.8	1.6，57.9
15	-12.6	0.2
				16	150.4	2	1.6，60.2
17	-20.4	0.2
				18	30.1	2.3	1.6，60.2
19	-30.1	15.1

EXAMPLE III

In the embodiment, the working distance WD =200mm, f/# =2.8 and the effective focal length f =11mm.

Fig. 7 is a graph of an optical transfer function MTF curve on each field image plane of the projection lens when the working distance WD =200mm, where the abscissa is spatial frequency, the ordinate is OTF mode value, the full field @93lp/mm >0.68, and the curve is close to the diffraction limit, which illustrates that the imaging quality of the lens is clear. Fig. 8 is a graph of field curvature and distortion. In fig. 8, the left graph is a field curvature graph, the abscissa is a field curvature value, and the ordinate is a field angle, wherein it can be seen that the maximum field curvature of sagittal view is <0.02mm, and the maximum field curvature of meridional view is <0.06mm. The right graph in fig. 8 is a distortion graph with the abscissa as a percentage of distortion and the ordinate as a field angle, in which a maximum distortion <0.06% can be seen. The third table is a structural parameter table of the projection lens in this embodiment.

Watch III

	Radius of curvature	Thickness (mm)	Material
				0		200
1	25.4	2	1.8，47
				2	-17.5	0.2
3	-15.5	1.1	1.6，60.2
				4	6.3	4.2
5	-90.4	1.1	1.8，47
				6	92.5	1.5
7	10.2	1.8	1.6，60.2
				8	-12.4	0.2
9		5
				10	-5.3	3.5	1.8，47
11	-9.4	0.2
				12	-20.1	1.1	1.8，24.5
13	31.2	1
				14	-31.2	1.8	1.6，57.9
15	-12.6	0.2
				16	150.4	2	1.6，60.2
17	-20.4	0.2
				18	30.1	2.3	1.6，60.2
19	-30.1	14.6

Example four

In the embodiment, the working distance WD =400mm, f/# =2.8 and the effective focal length f =11mm.

Fig. 9 is a graph of an optical transfer function MTF curve on each field image plane of the projection lens when the working distance WD =400mm, where the abscissa is spatial frequency, the ordinate is OTF mode value, the full field @93lp/mm >0.68, and the curve is close to the diffraction limit, which shows that the imaging quality of the lens is clear. Fig. 10 is a graph of field curvature and distortion. In fig. 10, the left graph is a field curvature graph, the abscissa is a field curvature value, and the ordinate is a field angle, wherein it can be seen that the sagittal maximum field curvature is <0.04mm, and the meridional maximum field curvature is <0.1mm. The right graph in fig. 10 is a distortion graph with the abscissa as a percentage of distortion and the ordinate as a field angle, in which a maximum distortion of <0.06% can be seen. The fourth table is a structural parameter table of the projection lens in this embodiment.

Watch four

	Radius of curvature	Thickness (mm)	Material
				0		400
1	25.4	2	1.8，47
				2	-17.5	0.2
3	-15.5	1.1	1.6，60.2
				4	6.3	4.2
5	-90.4	1.1	1.8，47
				6	92.5	1.5
7	10.2	1.8	1.6，60.2
				8	-12.4	0.2
9		5
				10	-5.2	3.5	1.8，47
11	-9.4	0.2
				12	-20.1	1.1	1.8，24.5
13	31.2	1
				14	-31.2	1.8	1.6，57.9
15	-12.6	0.2
				16	150.4	2	1.6，60.2
17	-20.4	0.2
				18	30.1	2.3	1.6，60.2
19	-30.1	14.7

The above detailed description is intended to illustrate the present invention, not to limit the present invention, and any modifications and changes made within the spirit of the present invention and the scope of the claims fall within the scope of the present invention.

Claims

1. The utility model provides a full high definition projection lens of low distortion which characterized in that includes:

the first focusing lens group has positive focal power and comprises a plurality of spherical lenses which are coaxially arranged, and the focal length of the first focusing lens group is f01;

the first converging lens group comprises four lenses, and the four lenses are a first biconvex lens with positive focal power, a second biconcave lens with negative focal power, a third biconcave lens with negative focal power and a fourth biconvex lens with positive focal power from the projection side to the imaging side;

a diaphragm;

the second converging lens group comprises five lenses which are sequentially a fifth meniscus thick lens with negative focal power, a sixth biconcave lens with negative focal power, a seventh meniscus lens with positive focal power, an eighth biconvex lens with positive focal power and a ninth biconvex lens with positive focal power from the projection side to the imaging side;

a display chip;

the difference between f01 and f02 is less than 1.

2. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the first converging mirror group focal lengths 15mm and the second converging mirror group focal lengths 15mm and the f02 and the 116mm are all-woven, and 1 and the f01/f02 and <1.1 are all-woven.

3. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the focal lengths of the first biconvex lenses are 12mm and f1 but 19mm, the focal lengths of the second biconcave lenses are-10mm and f2< -6mm, the focal lengths of the third biconcave lenses are-60mm and f3< -140mm, and the focal lengths of the fourth biconvex lenses are 8mm and f4< -13mm.

4. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the focal length of the fifth meniscus thick lens is-35mm & lt f5 & gt-25 mm, the focal length of the sixth biconcave lens is-12mm & lt f6 & lt-16 mm, the focal length of the seventh meniscus lens is 22mm & lt f7 & lt 32mm, the focal length of the eighth biconvex lens is 25mm & lt f8 & gt & lt 35mm, and the focal length of the ninth biconvex lens is 20mm & lt f9 & lt 26mm.

5. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the effective focal length of the projection lens is f, 1.3< -f01/f <1.5,1.3< -f02/f <1.5.

6. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the projection lens adopts a telecentric structure and adopts an image space telecentric light path, and the telecentric degree CRA is less than 0.1 degree.

7. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the spherical lenses of the first converging lens group and the second converging lens group are glass lenses, and the transmittance is higher than 95%.

8. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the total length of the projection lens is TTL, the effective focal length of the projection lens is f, then 2.7-less TTL/f is less than 2.8, the rear intercept of the projection lens is BFL, and then 1.3-less BFL/f is less than 1.4.

9. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the ratio of the distortion theta1 of the first converging lens group to the focal length is 0.15% < theta1/f01<0.2%, and the ratio of the distortion theta2 of the second converging lens group to the focal length is-0.12% < theta2/f02<0.2%.

10. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: the working distance WD =70-400mm for the projection lens.

11. The low-distortion full-high-definition projection lens according to claim 1, characterized in that: f/# =2-2.8, tr =0.65-1.05, fov =30-50 degrees for projection lens.