阅读说明：本技术 一种小型低f数高清投影镜头 (Small low-F-number high-definition projection lens ) 是由 周伟统 于 2019-10-09 设计创作，主要内容包括：本发明公开一种小型低F数高清投影镜头,包括投影镜头本体,所述投影镜头包括设于投影面和DMD芯片之间的反射镜和若干个同轴设置的透镜组件,所述透镜组件从投影面到DMD芯片之间的若干个同轴排布顺序是第一负透镜、双胶合透镜、三胶合透镜、第四凸透镜。本发明提供种小型低F数高清投影镜头,使用双非球面镜片来设计镜头,达到较高的清晰度；使用低F数设计,同时保证MTF保持较高数值；双非球面设计也满足低畸变的特殊需求。(The invention discloses a small low-F-number high-definition projection lens which comprises a projection lens body, wherein the projection lens comprises a reflector and a plurality of lens components, the reflector is arranged between a projection surface and a DMD chip, the lens components are coaxially arranged, and the lens components are a first negative lens, a double cemented lens, a triple cemented lens and a fourth convex lens from the projection surface to the DMD chip in sequence. The invention provides a small-sized low-F-number high-definition projection lens, which uses a double-aspheric lens to design the lens so as to achieve higher definition; a low F number design is used, and meanwhile, MTF is guaranteed to keep a higher value; the double aspheric design also meets the special requirement of low distortion.)

1. The utility model provides a small-size low F number high definition projection lens, includes the projection lens body, its characterized in that, the projection lens is including locating the speculum between plane of projection and the DMD chip and the coaxial lens subassembly that sets up of a plurality of, the lens subassembly is first negative lens, two cemented lens, three cemented lens, fourth convex lens from the coaxial order of arranging of a plurality of between plane of projection to the DMD chip.

2. The lens of claim 1, further comprising a prism set disposed between the DMD chip and the fourth convex lens and a stop surface disposed between the double cemented lens and the triple cemented lens.

3. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the DMD chip is 0.2 inch, the resolution is 854 multiplied by 480, the working surface of the DMD chip is vertical to the optical axis, and the center of the chip is aligned with the optical axis.

4. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the double cemented lens consists of a negative meniscus lens near the first negative lens and a convex lens near the diaphragm.

5. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the tri-cemented lens consists of a positive meniscus lens close to the diaphragm, a negative meniscus lens in the middle and a positive meniscus lens close to the fourth convex lens.

the refractive index of the fourth convex lens is between 1.45 and 1.60.

6. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the method is characterized in that: the focal length of the double cemented lens is 5-15 mm; the focal length of the triplexed cemented lens is between 100mm and positive infinity.

7. The small low-F-number high-definition projection lens as claimed in claim 1, wherein:

The refractive index of the first negative lens is between 1.45 and 1.60;

In the double cemented lens, the refractive index of the negative meniscus lens close to the first negative lens is between 1.45 and 1.60, and the refractive index of the convex lens close to the diaphragm is between 1.85 and 2.0;

In the triple cemented lens, the refractive index of a positive meniscus lens close to the diaphragm is between 1.55 and 1.65, the refractive index of a middle negative meniscus lens is between 1.70 and 1.80, and the refractive index of a positive meniscus lens close to the fourth convex lens is between 1.55 and 1.65; the refractive index of the fourth convex lens is between 1.45 and 1.60.

8. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the first negative lens and the fourth convex lens are aspheric lenses.

9. The small low-F-number high-definition projection lens as claimed in claim 1, wherein: the F-number is between 1.6 and 1.8.

Technical Field

The invention belongs to a projection technology in the photoelectric display industry, and particularly relates to a small low-F-number high-definition projection lens with high resolution.

Background

At present, the projector with higher pixels generally uses an aspheric projection lens, and the requirements on definition and TV distortion are easier to meet. The invention uses the aspheric lens to design the lens, and meets the requirements of higher definition and TV distortion of the aspheric surface. The requirement can be met by using a single aspheric lens for the common projection lens.

Typical projection lenses have F numbers between 2 and 2.5. And the low-F number projection lens less than 1.8 has higher light utilization rate when in use, and greatly improves the brightness of a projection picture of the projection lens by matching with the light source module. However, the low F number lens is difficult to design, and especially the low F number design can reduce the MTF, i.e. the sharpness of the image.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a small low-F number high-definition projection lens, which uses a double-aspheric lens to design the lens so as to achieve higher definition; a low F number design is used, and meanwhile, MTF is guaranteed to keep a higher value; the double aspheric design also meets the special requirement of low distortion.

the structure adopted by the invention is as follows: the utility model provides a small-size low F number high definition projection lens, includes the projection lens body, the projection lens is including locating the speculum between plane of projection and the DMD chip and the coaxial lens subassembly that sets up of a plurality of, the lens subassembly is first negative lens, two cemented lens, three cemented lens, fourth convex lens from the coaxial order of arranging of a plurality of between plane of projection to the DMD chip.

preferably, the projection lens further comprises a prism group arranged between the DMD chip and the fourth convex lens, and a diaphragm surface arranged between the double cemented lens and the triple cemented lens.

Furthermore, the DMD chip is 0.2 inch, the resolution is 854 multiplied by 480, the working surface of the DMD chip is perpendicular to the optical axis, and the center of the chip is aligned with the optical axis.

Further, the cemented doublet is composed of a negative meniscus lens near the first negative lens and a convex lens near the stop.

further, the triple cemented lens is composed of a positive meniscus lens near the diaphragm, a negative meniscus lens in the middle, and a positive meniscus lens near the fourth convex lens.

Further, the focal length of the double cemented lens is between 5 and 15 mm; the focal length of the triplexed cemented lens is between 100mm and positive infinity.

Further, the refractive index of the first negative lens is between 1.45 and 1.60; in the double cemented lens, the refractive index of the negative meniscus lens close to the first negative lens is between 1.45 and 1.60, and the refractive index of the convex lens close to the diaphragm is between 1.85 and 2.0; in the triple cemented lens, the refractive index of a positive meniscus lens close to the diaphragm is between 1.55 and 1.65, the refractive index of a middle negative meniscus lens is between 1.70 and 1.80, and the refractive index of a positive meniscus lens close to the fourth convex lens is between 1.55 and 1.65; the refractive index of the fourth convex lens is between 1.45 and 1.60.

Further, the F-number is between 1.6 and 1.8.

Further, the first negative lens and the fourth convex lens are aspheric lenses.

The invention has the beneficial effects that:

1. The invention provides a projection lens with low F number of 1.7, projection ratio of 1.15, distortion of less than 0.6% and focal length of 5.3 mm;

2. The lens is an imaging objective lens with simple structure and cost control and optimization. An image surface with the width of 1m is formed at the position of 1.15m after passing through the lens system;

3. Based on the optical imaging principle, the invention uses optical design software to repeatedly carry out structure on the projection objective to achieve the optimal design of aberration;

4. The lens is designed by using a double-aspheric lens to achieve higher definition; a low F number design is used, and meanwhile, MTF is guaranteed to keep a higher value; the double aspheric design also meets the special requirement of low distortion.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a graph of MTF for the present invention;

fig. 3 is a dot diagram of the present invention.

In the figure: 1. a DMD chip; 2. a diaphragm surface; 3. a first negative lens; 4. a double cemented lens; 5. a tri-cemented lens; 4.1, a negative meniscus lens adjacent to the first negative lens; 4.2 convex lens near the diaphragm; 5.1, a positive meniscus lens close to the diaphragm; 5.2, a central negative meniscus lens; 5.3, a positive meniscus lens adjacent to the fourth convex lens; 6. a fourth convex lens; 7. prism group, 8, window glass.

Detailed Description

The embodiments of the present invention will be further explained with reference to the drawings.

The structure adopted by the invention in fig. 1 is: the utility model provides a small-size low F number high definition projection lens, includes the projection lens body, the projection lens is including locating speculum and the coaxial lens subassembly that sets up of a plurality of between plane of projection and the DMD chip 1, the lens subassembly is first negative lens 3, two cemented lens 4, three cemented lens 5, fourth convex lens 6 and window glass 8 from the coaxial order of arranging of a plurality of between plane of projection to the DMD chip.

The projection lens further comprises a prism group 7 arranged between the DMD chip and the fourth convex lens and a diaphragm surface 2 arranged between the double-cemented lens and the triple-cemented lens.

The DMD chip is 0.2 inch, the resolution is 854 multiplied by 480, the working surface of the DMD chip is vertical to the optical axis, and the center of the chip is aligned with the optical axis.

the cemented doublet consists of a negative meniscus lens 4.1 near the first negative lens and a convex lens 4.2 near the diaphragm.

The tri-cemented lens consists of a positive meniscus lens 5.1 close to the diaphragm, a negative meniscus lens 5.2 in the middle and a positive meniscus lens 5.3 close to the fourth convex lens.

The focal length of the double cemented lens is 5-15 mm; the focal length of the triplexed cemented lens is between 100mm and positive infinity.

the refractive index of the first negative lens is between 1.45 and 1.60; in the double cemented lens, the refractive index of the negative meniscus lens close to the first negative lens is between 1.45 and 1.60, and the refractive index of the convex lens close to the diaphragm is between 1.85 and 2.0; in the triple cemented lens, the refractive index of a positive meniscus lens close to the diaphragm is between 1.55 and 1.65, the refractive index of a middle negative meniscus lens is between 1.70 and 1.80, and the refractive index of a positive meniscus lens close to the seventh convex lens is between 1.55 and 1.65; the refractive index of the fourth convex lens is between 1.45 and 1.60.

The first negative lens and the fourth convex lens are aspheric lenses.

the curvature radius, material and thickness of each lens and the distance between the lenses are modified to achieve the optimization of aberration.

The following is an example of a 0.20 inch DMD chip, which provides parameters for an embodiment of the optical system of the projection lens of the present invention.

Aspherical surface coefficient:

Surface	x2	x4	x6
				2	0	1.68183E-03	-2.57411E-06
11	0	2.01547E-04	-2.48192E-06
				12	0	2.68413E-04	-5.07614E-07

finally, the optical projection lens with the projection ratio of 1.15, the focal length of 5.3mm, the total length from the first surface to the working surface of the chip of less than 31mm, F1.7, the distortion of less than 0.6 percent, uniform image quality of each field of view and optimal image quality is obtained. The invention realizes that an image surface with the width of 1m is formed at the position of 1.15 m.

FIG. 2 is a MTF graph of the present invention, in which the MTF curves of the fields under 93lp/mm are compacted into a bundle of curves larger than 0.52, which shows that the image of the lens is clear and uniform. The pixels of a 0.2 inch DMD chip are 5.4 microns, corresponding to a quinis line pair of 93lp/mm, and an MTF value >0.52 under the line pair meets the resolution requirement of the chip.

Fig. 3 is a point diagram of the present invention, and it is known that the average diffuse spot radius of the point diagram under each field of view is less than 5.210 micrometers, and the image quality is good.