CN102879888B - Fixed focus projection lens - Google Patents

Abstract

The invention relates to a fixed focus projection lens which comprises a first lens group and a second lens group which are sequentially arranged along an optical axis from the imaging side to the image source side, wherein the first lens group has positive refractive power and comprises a first lens and a second lens which are sequentially arranged; the first lens is made of a plastic material and has negative refractive power; the second lens is made of a glass material and has positive refractive power; the second lens group has positive refractive power and comprises a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged; the third lens is made of the plastic material and has negative refractive power; the fourth lens is made of the glass material and has negative refractive power; the fifth lens is made of the glass material, has positive refractive power and is glued with the fourth lens to form a composite lens with negative refractive power; the sixth lens is made of the plastic material and has positive refractive power; and the seventh lens is made of the glass material and has negative refractive power.

Description

Fixed focus projection lens

Technical field

The present invention is relevant with projector, in more detail refers to a kind of fixed focus projection lens.

Background technology

In recent years, along with the progress of image science and technology, utilize projector to carry out bulletin, video signal, meeting or the people of ornamental film and get more and more.And carry and use for making projection function be more convenient for, its in order to by image definition be presented on the fixed focus projection lens on screen volume also will be reduced significantly, to meet desired miniaturization and light-weighted demand, moreover, except miniaturization and lightweight, also want to have higher optical performance, the image reaching high resolving power and high contrast just can be made to represent.Therefore, miniaturization and high optical performance are indispensable two important documents of fixed focus projection lens.

But known fixed focus projection lens includes the mirror group of more than three groups usually, and must be separated with certain intervals between those mirrors group, simultaneously those mirrors group includes all again plural pieces lens, between those lens mostly again between be separated with certain distance.Therefore, known fixed focus projection lens is the large and Heavy Weight of volume not only, and cannot reach miniaturization and light-weighted design, more because of its inner mirror group and lens more, therefore longer group need be expended during making and stand man-hour, and spent material cost also not easily reduces.Comprehensively the above can be learnt, known fixed focus projection lens is not attained perfect yet, and the part that haves much room for improvement.

Summary of the invention

The technical problem to be solved in the present invention is, for the defect that the mirror group of fixed focus projection lens of the prior art is more, provides a kind of fixed focus projection lens, and being made up of two arrangement of mirrors groups, not only volume is little, and has high optical performance.

The technical scheme that the present invention adopts for its technical matters of solution is, a kind of fixed focus projection lens is provided, to include along optical axis and by the first mirror group and the second mirror group that become image side to image source side sequential, wherein, this the first mirror group has positive refractive power, and includes by this one-tenth image side to the first eyeglass of this image source side sequential and the second eyeglass; This first eyeglass is made up of plastic material, and has negative refractive power; This second eyeglass is made up of glass material, and has positive refractive power; This second mirror group has positive refractive power, and includes by this one-tenth image side to the 3rd eyeglass of this image source side sequential, the 4th eyeglass, the 5th eyeglass, the 6th eyeglass and the 7th eyeglass; 3rd eyeglass is made up of plastic material, and has negative refractive power; 4th eyeglass is made up of glass material, and has negative refractive power; 5th eyeglass is made up of glass material, and has positive refractive power, and the 5th eyeglass and the 4th eyeglass glue together the compound lens forming and have negative refractive power; 6th eyeglass is made up of plastic material, and has positive refractive power; 7th eyeglass is made up of glass material, and has negative refractive power.

By this, above-mentioned lens design is utilized to make this fixed focus projection lens have the object reaching miniaturization and high optical performance.

Accompanying drawing explanation

Fig. 1 is the eyeglass arrangement plan of the present invention first preferred embodiment;

Fig. 2 A is the curvature of field figure of the present invention first preferred embodiment;

Fig. 2 B is the distortion figure of the present invention first preferred embodiment;

Fig. 2 C is the longitudinal chromatic aberration figure of the present invention first preferred embodiment;

Fig. 2 D is the light fan figure of the present invention first preferred embodiment;

Fig. 2 E is the Space Frequency Modulation transport function figure of the present invention first preferred embodiment;

Fig. 3 is the eyeglass arrangement plan of the present invention second preferred embodiment;

Fig. 4 A is the curvature of field figure of the present invention second preferred embodiment;

Fig. 4 B is the distortion figure of the present invention second preferred embodiment;

Fig. 4 C is the longitudinal chromatic aberration figure of the present invention second preferred embodiment;

Fig. 4 D is the light fan figure of the present invention second preferred embodiment;

Fig. 4 E is the Space Frequency Modulation transport function figure of the present invention second preferred embodiment.

Embodiment

For can the present invention be illustrated more clearly in, hereby lifts preferred embodiment and coordinate accompanying drawing to be described in detail as follows.

Referring to Fig. 1, is the eyeglass arrangement plan of the present invention first preferred embodiment fixed focus projection lens 1, and this fixed focus projection lens 1 includes along optical axis Z and by the first mirror group G1 and the second mirror group G2 that become image side to image source side sequential.In addition, inner full-reflection prism TP (Total internal reflection Prism) and glass covering CG (Cover Glass) is more sequentially provided with between this second mirror group G2 to image source side, its function belongs to existing skill, repeats no more in this appearance.Wherein:

This first mirror group G1 has positive refractive power, and includes by the first eyeglass L1 and the second eyeglass L2 that become image side to image source side sequential.This first eyeglass L1 is made up of plastic material.This first eyeglass L1 is the meniscus lens with negative refractive power, and its convex surface R1 is towards one-tenth image side, and its convex surface R1 and concave surface R2 is all non-spherical surface.This second eyeglass L2 is made up of glass material.This second eyeglass L2 is the meniscus lens with positive refractive power, and its convex surface R3 is towards one-tenth image side.

This second mirror group G2 has positive refractive power, and includes by the 3rd eyeglass L3, the 4th eyeglass L4 that become image side to image source side sequential, the 5th eyeglass L5, the 6th eyeglass L6 and the 7th eyeglass L7.3rd eyeglass L3 is made up of plastic material.3rd eyeglass L3 is the meniscus lens with negative refractive power, and its convex surface R5 is towards one-tenth image side, and its convex surface R5 and concave surface R6 is all non-spherical surface.In addition, the aperture ST of this fixed focus projection lens 1 is positioned on the convex surface R5 of the 3rd eyeglass L3.4th eyeglass L4 is made up of glass material.4th eyeglass L4 is the biconcave lens with negative refractive power.5th eyeglass L5 is made up of glass material.5th eyeglass L5 is the biconvex lens with positive refractive power, and the 5th eyeglass L5 and the 4th eyeglass L4 glues together the compound lens L45 forming and have negative refractive power.6th eyeglass L6 is made up of plastic material.6th eyeglass L6 is the biconvex lens with positive refractive power, and two convex surface R10, R11 are all non-spherical surface.7th eyeglass L7 is made up of glass material.7th eyeglass L7 is the biconvex lens with positive refractive power.

In addition, in order to effectively reduce this fixed focus projection lens 1 overall length and volume, and revise aberration, to reach preferably image quality, this fixed focus projection lens 1 meets following condition:

(1)1.75＜|F1/F|＜1.83

(2)0.80＜|F2/F|＜0.82

(3)1.95＜|FL1/F|＜2.33

(4)0.57＜|v4/v5|＜0.61

(5)8.50＜|ex/lt|＜17.0

(6)Nd _L2＞1.80

Wherein, F is the focal length of this fixed focus projection lens 1; F1 is the focal length of this first mirror group G1; F2 is the focal length of this second mirror group G2; FL1 is the focal length of this first eyeglass L1; V4 is the abbe number of the 4th eyeglass L4; V5 is the abbe number of the 5th eyeglass L5; Ex is the exit pupil position (exit pupil position) of this fixed focus projection lens 1; Lt is the length of this fixed focus projection lens 1; Nd _l2for the refractive index (refractive index) of this second eyeglass L2.

For reaching above-mentioned purpose and effective optical performance promoting this fixed focus projection lens 1, focal length F (Focus Length), the numerical aperture FNO (F-number) of the fixed focus projection lens 1 of first embodiment of the invention, radius-of-curvature (radius of curvature), the refractive index Nd (refractive index) of the spacing of each eyeglass, each eyeglass and the Abbe number Vd (Abbe number) of each eyeglass of the optical axis Z of each lens surface by locating, as shown in Table 1:

Table one

In each eyeglass of the present embodiment, the surface indentation degree D of these non-spherical surfaces R1, R2, R5, R6, R10 and R11 obtained by following formula:

$D=\frac{C\·H^2}{1+\sqrt{1-(1+K)\·C^2\·H^2}}+E_4\·H^4+E_6\·H^6+E_8\·H^8+E_{10}\·H^{10}+E_{12}\·H^{12}+E_{14}\·H^{14}+E_{16}\·H^{16}$

D: the depression degree of non-spherical surface;

C: the inverse of radius-of-curvature;

H: the aperture radius on surface;

K: circular cone coefficient;

E4 ~ E16: each rank coefficient of the aperture radius H on surface.

In the present embodiment, each rank coefficient E4 ~ E16 of the circular cone COEFFICIENT K (conic constant) of each non-spherical surface and surface apertures radius H is as shown in Table 2:

Table two

The eyeglass of above and the configuration of aperture, make the fixed focus projection lens 1 of the present embodiment not only effectively reduced volume to meet the demand of lightweight device for image, image quality also can reach requirement, this can find out from Fig. 2 A to Fig. 2 E.

Shown in Fig. 2 A, be the curvature of field (Field Curvature) figure of the fixed focus projection lens 1 of the present embodiment; Shown in Fig. 2 B, be distortion (Distortion) figure of the fixed focus projection lens 1 of the present embodiment; Shown in Fig. 2 C, be longitudinal chromatic aberration (Longitudinal) figure of the fixed focus projection lens 1 of the present embodiment; Shown in Fig. 2 D, be light fan (Ray Fan) figure of the fixed focus projection lens 1 of the present embodiment; Shown in Fig. 2 E, be the Space Frequency Modulation transport function figure (Spatial Frequency MTF) of the fixed focus projection lens 1 of the present embodiment.

Can be found out by Fig. 2 A, the maximum curvature of field of the present embodiment is no more than 0.06mm and-0.04mm; Can be found out by Fig. 2 B, the amount of distortion of the present embodiment is no more than 1.2%; Can be found out by Fig. 2 C, the maximum longitudinal chromatic aberration of the present embodiment is maximum is no more than 0.04mm and-0.02mm; Can be found out by Fig. 2 D, the present embodiment all has good resolution in which field positions; Can be found out by Fig. 2 E, the present embodiment is when 80lp/mm, and its modulated optical transfer function values still maintains more than 40%, and the resolution of the fixed focus projection lens 1 of obvious the present embodiment is standard compliant.

Above-described, be the fixed focus projection lens 1 of the present invention first preferred embodiment; According to technology of the present invention, below coordinate Fig. 3 that the fixed focus projection lens 2 of the present invention second preferred embodiment is described.

This fixed focus projection lens 2 includes along optical axis Z and by the first mirror group G1 and the second mirror group G2 that become image side to image source side sequential.In addition, inner full-reflection prism TP (Total internal reflection Prism) and glass covering CG (Cover Glass) is equally sequentially provided with between this second mirror group G2 to image source side.Wherein:

This first mirror group G1 has positive refractive power, and includes by the first eyeglass L1 and the second eyeglass L2 that become image side to image source side sequential.This first eyeglass L1 is made up of plastic material.This first eyeglass L1 is the meniscus lens with negative refractive power, and its convex surface R1 is towards one-tenth image side, and its convex surface R1 and concave surface R2 is all non-spherical surface.This second eyeglass L2 is made up of glass material.This second eyeglass L2 is the meniscus lens with positive refractive power, and its convex surface R3 is towards one-tenth image side.

This second mirror group G2 has positive refractive power, and includes by the 3rd eyeglass L3, the 4th eyeglass L4 that become image side to image source side sequential, the 5th eyeglass L5, the 6th eyeglass L6 and the 7th eyeglass L7.3rd eyeglass L3 is made up of plastic material.3rd eyeglass L3 is the meniscus lens with negative refractive power, and its convex surface R5 is towards one-tenth image side, and its convex surface R5 and concave surface R6 is all non-spherical surface.In addition, the aperture ST of this fixed focus projection lens 2 is positioned on the convex surface R5 of the 3rd eyeglass L3.4th eyeglass L4 is made up of glass material.4th eyeglass L4 is the biconcave lens with negative refractive power.5th eyeglass L5 is made up of glass material.5th eyeglass L5 is the biconvex lens with positive refractive power, and the 5th eyeglass L5 and the 4th eyeglass L4 glues together the compound lens L45 forming and have negative refractive power.6th eyeglass L6 is made up of plastic material.6th eyeglass L6 is the biconvex lens with positive refractive power, and two convex surface R10, R11 are all non-spherical surface.7th eyeglass L7 is made up of glass material.7th eyeglass L7 is the biconvex lens with positive refractive power.

Similarly, in order to effectively reduce this fixed focus projection lens 2 overall length and volume, and revise aberration, to reach preferably image quality, this fixed focus projection lens 2 also meets following condition:

(1)1.75＜|F1/F|＜1.83

(2)0.80＜|F2/F|＜0.82

(3)1.95＜|FL1/F|＜2.33

(4)0.57＜|v4/v5|＜0.61

(5)8.50＜|ex/lt|＜17.0

(6)Nd _L2＞1.80

Wherein, F is the focal length of this fixed focus projection lens 2; F1 is the focal length of this first mirror group G1; F2 is the focal length of this second mirror group G2; FL1 is the focal length of this first eyeglass L1; V4 is the abbe number of the 4th eyeglass L4; V5 is the abbe number of the 5th eyeglass L5; Ex is the exit pupil position (exit pupil position) of this fixed focus projection lens 2; Lt is the length of this fixed focus projection lens 2; Nd _l2for the refractive index (refractive index) of this second eyeglass L2.

For reaching above-mentioned purpose and effective optical performance promoting this fixed focus projection lens 2, focal length F (Focus Length), the numerical aperture FNO (F-number) of the fixed focus projection lens 2 of second embodiment of the invention, radius-of-curvature (radius of curvature), the refractive index Nd (refractive index) of the spacing of each eyeglass, each eyeglass and the Abbe number Vd (Abbe number) of each eyeglass of the optical axis Z of each lens surface by locating, as shown in Table 3:

Table three

In each eyeglass of the present embodiment, the surface indentation degree D of these non-spherical surfaces R1, R2, R5, R6, R10 and R11 obtained by following formula:

$D=\frac{C\·H^2}{1+\sqrt{1-(1+K)\·C^2\·H^2}}+E_4\·H^4+E_6\·H^6+E_8\·H^8+E_{10}\·H^{10}+E_{12}\·H^{12}+E_{14}\·H^{14}+E_{16}\·H^{16}$

D: the depression degree of non-spherical surface;

C: the inverse of radius-of-curvature;

H: the aperture radius on surface;

K: circular cone coefficient;

E4 ~ E16: each rank coefficient of the aperture radius H on surface.

In the present embodiment, each rank coefficient E4 ~ E16 of the circular cone COEFFICIENT K (conic constant) of each non-spherical surface and surface apertures radius H is as shown in Table 4:

Table four

The eyeglass of above and the configuration of aperture, make the fixed focus projection lens 2 of the present embodiment not only effectively reduced volume to meet the demand of lightweight device for image, image quality also can reach requirement, this can find out from Fig. 4 A to Fig. 4 E.

Shown in Fig. 4 A, be the curvature of field (Field Curvature) figure of the fixed focus projection lens 2 of the present embodiment; Shown in Fig. 4 B, be distortion (Distortion) figure of the fixed focus projection lens 2 of the present embodiment; Shown in Fig. 4 C, be longitudinal chromatic aberration (Longitudinal) figure of the fixed focus projection lens 2 of the present embodiment; Shown in Fig. 4 D, be light fan (Ray Fan) figure of the fixed focus projection lens 2 of the present embodiment; Shown in Fig. 4 E, be the Space Frequency Modulation transport function figure (Spatial Frequency MTF) of the fixed focus projection lens 2 of the present embodiment.

Can be found out by Fig. 4 A, the maximum curvature of field of the present embodiment is no more than 0.08mm and-0.02mm; Can be found out by Fig. 4 B, the amount of distortion of the present embodiment is no more than 1.2%; Can be found out by Fig. 4 C, the maximum longitudinal chromatic aberration of the present embodiment is maximum is no more than 0.05mm and-0.02mm; Can be found out by Fig. 4 D, the present embodiment all has good resolution in which field positions; Can be found out by Fig. 4 E, the present embodiment is when 80lp/mm, and its modulated optical transfer function values still maintains more than 30%, and the resolution of the fixed focus projection lens 2 of obvious the present embodiment is standard compliant.

Comprehensive above can to learn, fixed focus projection lens of the present invention not only can effectively reduced volume and while can have high optical performance.

The foregoing is only the better possible embodiments of the present invention, the equivalent structure that all application instructions of the present invention and claim are done and method for making change, ought to be included in the scope of the claims of the present invention.

Claims (11)

1. a fixed focus projection lens, is characterized in that, includes along optical axis and by becoming image side to image source side sequential:

First mirror group, has positive refractive power, and includes by this one-tenth image side to the first eyeglass of this image source side sequential and the second eyeglass; This first eyeglass is made up of plastic material, and has negative refractive power; This second eyeglass is made up of glass material, and has positive refractive power; And

Second mirror group, has positive refractive power, and includes by this one-tenth image side to the 3rd eyeglass of this image source side sequential, the 4th eyeglass, the 5th eyeglass, the 6th eyeglass and the 7th eyeglass; 3rd eyeglass is made up of plastic material, and has negative refractive power; 4th eyeglass is made up of glass material, and has negative refractive power; 5th eyeglass is made up of glass material, and has positive refractive power, and the 5th eyeglass and the 4th eyeglass glue together the compound lens forming and have negative refractive power; 6th eyeglass is made up of plastic material, and has positive refractive power; 7th eyeglass is made up of glass material, and has positive refractive power.

2. fixed focus projection lens as claimed in claim 1, is characterized in that, this first eyeglass at least one side is non-spherical surface.

3. fixed focus projection lens as claimed in claim 1, it is characterized in that, the refractive index of this second eyeglass is greater than 1.80.

4. fixed focus projection lens as claimed in claim 1, is characterized in that, the 3rd eyeglass at least one side is non-spherical surface.

5. fixed focus projection lens as claimed in claim 1, is characterized in that, more include aperture, be positioned at the 3rd eyeglass towards on the face of this one-tenth image side.

6. fixed focus projection lens as claimed in claim 1, is characterized in that, the 6th eyeglass at least one side is non-spherical surface.

7. fixed focus projection lens as claimed in claim 1, is characterized in that, more meet following condition:

1.75<|F1/F|<1.83, wherein, F1 is the focal length of this first mirror group; F is the focal length of this fixed focus projection lens.

8. fixed focus projection lens as claimed in claim 1, is characterized in that, more meet following condition:

0.80<|F2/F|<0.82, wherein, F2 is the focal length of this second mirror group; F is the focal length of this fixed focus projection lens.

9. fixed focus projection lens as claimed in claim 1, is characterized in that, more meet following condition:

1.95<|FL1/F|<2.33, wherein, FL1 is the focal length of this first eyeglass; F is the focal length of this fixed focus projection lens.

10. fixed focus projection lens as claimed in claim 1, is characterized in that, more meet following condition:

0.57<|v4/v5|<0.61, wherein, v4 is the abbe number of the 4th eyeglass; V5 is the abbe number of the 5th eyeglass.

11. fixed focus projection lens as claimed in claim 1, is characterized in that, more meet following condition:

8.50<|ex/lt|<17.0, wherein, ex is the exit pupil position of this fixed focus projection lens; Lt is the length of this fixed focus projection lens.