CN108983408B - Adjustable eyepiece system with adaptive eye distance - Google Patents

Abstract

An eye-distance adjustable eyepiece system comprises an aperture, a first lens with refractive power, a second lens with positive refractive power, a third lens with negative refractive power and a fourth lens with positive refractive power in sequence from an object side to an image side along an optical axis. The first lens, the second lens, the third lens, the fourth lens and the fourth lens are suitable for moving towards the object side or the image side together according to the eye relief distance of a user. The first lens element to the fourth lens element each include an object-side surface and an image-side surface. The adjustable eye lens system with the eye distance meets the following requirements: 0< | R5/f3| <3.5, where R5 is the radius of curvature of the object-side surface of the third lens, and f3 is the focal length of the third lens.

Description

Adjustable eyepiece system with adaptive eye distance

Technical Field

The present invention relates to an optical system, and more particularly, to an eye-distance adjustable eyepiece system.

Background

With the change of science and technology, the application range of the optical lens set is not limited to a telescope and a microscope, but is also widely applied to electronic products such as an electronic viewfinder (view finder) and a head-mounted display. A Head-Mounted Display (HMD) mainly transfers content displayed on the Display to human eyes through an optical lens set, so that the human eyes perceive an enlarged virtual image.

Current head mounted displays include light transmissive head mounted displays as well as non-light transmissive head mounted displays. The light-transmitting head-mounted display can enable human eyes to receive contents displayed by the display and external images. The non-light-transmitting head-mounted display only allows the human eye to receive the content displayed by the display, and allows the user to be completely immersed in the virtual world. Therefore, a non-light transmissive head-mounted display needs to have good imaging quality and a large Field Of View (FOV) so that a user does not feel uncomfortable using the head-mounted display for a long time. In the prior art, the eye relief of the head-mounted display (i.e., the maximum distance between the eye and the optical lens group that the user can clearly see the image) is generally designed to be a constant value (15 mm). However, in actual use, the actual eye relief may be different from the above design value due to the user's myopia or hyperopia. Therefore, there is a need for a display system having a large field angle, good imaging quality, and adjustable eye relief.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide an eye-distance adjustable eyepiece system, which has a large field angle, good imaging quality and adjustable eye-distance.

In order to achieve the above object, the present invention provides an eye-distance adjustable eyepiece system including, in order from an object side to an image side along an optical axis, an aperture, a first lens having a refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a fourth lens having a positive refractive power. The first lens, the second lens, the third lens, the fourth lens and the fourth lens are suitable for moving towards the object side or the image side together according to the eye relief distance of a user. The first lens element to the fourth lens element each include an object-side surface facing the object side and passing the imaging light and an image-side surface facing the image side and passing the imaging light. The adjustable eye lens system with the eye distance meets the following requirements: 0< | R5/f3| <3.5, where R5 is the radius of curvature of the object-side surface of the third lens, and f3 is the focal length of the third lens.

In an embodiment of the present invention, the eye-distance adjustable eyepiece system further satisfies the following conditions: 0.7< | Φ 3/(Φ 1+ Φ 2) | <4.5, where Φ 1 is the reciprocal of the focal length of the first lens, Φ 2 is the reciprocal of the focal length of the second lens, and Φ 3 is the reciprocal of the focal length of the third lens.

In an embodiment of the present invention, the eye-distance adjustable eyepiece system further satisfies the following conditions: l V2-V3 l >20, where V2 is the Abbe number of the second lens and V3 is the Abbe number of the third lens.

In an embodiment of the present invention, the eye-distance adjustable eyepiece system further satisfies the following conditions: 1.5< TTL/D2<5.5, where TTL is the distance on the optical axis from the aperture stop to the display, and D2 is the distance on the optical axis from the aperture stop to the object side of the first lens.

In an embodiment of the invention, an object-side surface of the second lens element is convex in a region near the optical axis. At least one of the object side surface and the image side surface of the second lens is an aspheric surface. The object side surface of the third lens is concave in the vicinity of the optical axis. At least one of the object side surface and the image side surface of the third lens is an aspheric surface. The object side surface of the fourth lens is convex in the vicinity of the optical axis. At least one of the object side surface and the image side surface of the fourth lens is an aspheric surface.

In an embodiment of the invention, the refractive power of the first lens is positive. The object side surface of the first lens is convex in the vicinity of the optical axis. The image side surface of the second lens is convex in the vicinity of the optical axis. The image side surface of the fourth lens is concave in the vicinity of the optical axis.

In an embodiment of the invention, the refractive power of the first lens is negative. The image side surface of the first lens is concave in a region near the optical axis, and the image side surface of the third lens is convex in a region near the optical axis.

In an embodiment of the invention, the object-side surface of the first lens is concave in a region near the optical axis. The image side surface of the second lens is convex in the vicinity of the optical axis. The image side surface of the fourth lens is convex in the vicinity of the optical axis.

In an embodiment of the invention, an object-side surface of the first lens element is convex in a region near the optical axis. The image side surface of the second lens is concave in the vicinity of the optical axis. The image side surface of the fourth lens is concave in the vicinity of the optical axis.

In an embodiment of the invention, the object-side surface and the image-side surface of each of the second lens element, the third lens element and the fourth lens element are aspheric.

The invention has the technical effects that:

based on the above, the ocular distance adjustable eyepiece system of the embodiment of the invention has the beneficial effects that: by means of the design and arrangement of the concave-convex shape of the object side surface or the image side surface of the lens, the eye-distance-adaptive adjustable eyepiece system has a large field angle, good imaging quality and adjustable eye distance.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIGS. 1A and 1B are schematic diagrams illustrating a first embodiment of an eye-distance adjustable eyepiece system with diopters of +2D and-8D respectively;

FIGS. 2 and 3 are graphs of field curvature aberration (field curvature aberration) for the diopters of +2D and-8D for the eye-distance adjustable eyepiece system of the first embodiment;

FIGS. 4 and 5 are graphs of distortion aberration (aberration) of the first embodiment of the eye-distance adjustable eyepiece lens system with diopters of +2D and-8D;

FIGS. 6A to 6F and FIGS. 7A to 7F are cross beam fan diagrams with diopters of +2D and-8D of the eye-distance adjustable eyepiece system of the first embodiment, respectively;

FIGS. 8A and 8B are diagrams illustrating an eye-distance adjustable eyepiece system according to a second embodiment of the present invention with diopters of +2D and-8D respectively;

FIGS. 9 and 10 are graphs of the field curvature aberration for the diopters +2D and-8D of the eye-fitted distance adjustable eyepiece system of the second embodiment;

FIGS. 11 and 12 are graphs of distortion aberrations of the second embodiment of the eye-distance adjustable eyepiece system with diopters of +2D and-8D;

FIGS. 13A to 13F and FIGS. 14A to 14F are cross beam fan diagrams with diopters of +2D and-8D of the eye-distance adjustable eyepiece system of the second embodiment, respectively;

FIGS. 15A and 15B are diagrams illustrating an eye-distance adjustable eyepiece system according to a third embodiment of the present invention with diopters of +2D and-8D respectively;

FIGS. 16 and 17 are graphs of the field curvature aberration when the diopter scale of the eye-fitted distance adjustable eyepiece system of the third embodiment is +2D and-8D, respectively;

FIGS. 18 and 19 are distortion aberration diagrams at diopters +2D and-8D of the eye-distance adjustable eyepiece system of the third embodiment;

FIGS. 20A to 20F and FIGS. 21A to 21F are cross beam fan diagrams at diopters of +2D and-8D of the eye-distance adjustable eyepiece system of the third embodiment, respectively;

FIGS. 22A and 22B are diagrams illustrating an eye-distance adjustable eyepiece system according to a fourth embodiment of the present invention with diopters of +2D and-8D respectively;

FIGS. 23 and 24 are graphs of the field curvature aberration when the diopter scale of the eye-fitted distance adjustable eyepiece system of the fourth embodiment is +2D and-8D, respectively;

FIGS. 25 and 26 are distortion aberration diagrams at diopters +2D and-8D of the eye-distance adjustable eyepiece system of the fourth embodiment;

fig. 27A to 27F and fig. 28A to 28F are transverse beam fan diagrams at diopter +2D and-8D of the eye-distance adjustable eyepiece system of the fourth embodiment, respectively.

Wherein the reference numerals

1: first lens

2: second lens

3: third lens

4: fourth lens

9: display device

10: adjustable eyepiece system with adaptive eye distance

11. 21, 31, 41: side of the object

12. 22, 32, 42: image side

A: aperture

I: optical axis

Detailed Description

The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:

in the present specification, "eye relief" refers to the distance on the optical axis from the aperture (or one eye of the user) to the first lens of the eye-relief adjustable eyepiece system. The eye-distance adjustable eyepiece system may be applied to a head-mounted display, and the head-mounted display may have two eye-distance adjustable eyepiece systems corresponding to left and right eye settings of a user. The two eye-distance adjustable eyepiece systems can adjust (manually or automatically) the respective eye distances according to the eyesight of the left eye and the right eye.

In the case of a non-light-transmissive head-mounted display, the two eye-distance adjustable eyepiece systems may be respectively mounted in front of the left and right eyes of the user, and one display may be respectively disposed in front of the two eye-distance adjustable eyepiece systems, or one display may be shared by the two eye-distance adjustable eyepiece systems. Since the display is opaque and is mounted in front of the user's line of sight, the user cannot see the external image and can be completely immersed in the virtual world.

In the case of a transparent head-mounted display, the display and the eye distance adjustable eyepiece system can be mounted around the user's eyes without shielding the user's sight, and the light beam from the display and passing through the eye distance adjustable eyepiece system is transmitted to the user's eyes through the beam splitter and the light guide element. Because the light-shielding element (such as a display) in the head-mounted display does not shield the sight of the user, the user can receive the content displayed by the display and the external image.

In the present specification, the term "a lens has a positive refractive power (or a negative refractive power)" means that the refractive power on the optical axis of the lens calculated by the gaussian optical theory is positive (or negative). In the eye-distance adjustable eyepiece system, each lens is radially symmetrical to each other with the optical axis as a symmetry axis. Each lens has an object side surface and an image side surface opposite to the object side surface. The object side and the image side define the range through which the imaging light rays pass, wherein the imaging light rays include a chief ray (chief ray) and a marginal ray (margin ray). The object side surface (or image side surface) has a vicinity region of the optical axis and an edge region connecting and surrounding the vicinity region of the optical axis. The vicinity of the optical axis is a region on the optical axis through which the imaging light passes. The edge region is a region through which edge light passes.

"a region of one surface (object-side surface or image-side surface) of the lens near the optical axis is a convex surface or a concave surface" is determined by the positive or negative of the R value (which means the paraxial radius of curvature) of the region of the surface near the optical axis. Regarding the object side, when the R value is positive, it is determined that the object side is convex in the vicinity of the optical axis, that is, the object side has a convex portion (covex portion) in the vicinity of the optical axis; when the R value is negative, it is determined that the object side surface is concave in the vicinity of the optical axis, that is, the object side surface has a concave portion (concave portion) in the vicinity of the optical axis. When the R value is positive, the image side surface is determined to be concave in the vicinity of the optical axis, that is, the image side surface has a concave surface portion in the vicinity of the optical axis; when the R value is negative, it is determined that the image side surface is convex in the vicinity of the optical axis, that is, the image side surface has a convex portion in the vicinity of the optical axis.

A surface (object side or image side) of the lens may have more than one convex portion, more than one concave portion, or a combination of both. When the surface has a convex surface portion and a concave surface portion, the surface has an inflection point. The inflection point is the transition point between the convex surface portion and the concave surface portion. That is, the surface is concave by convex, or convex by concave at points of reverse curvature. On the other hand, when the surface has only a convex surface portion or only a concave surface portion, the surface does not have an inflection point.

Fig. 1A and 1B are schematic diagrams illustrating an eye-distance adjustable eyepiece system according to a first embodiment of the invention with diopters of +2D and-8D respectively. Referring to fig. 1A and 1B, an eye-distance adjustable eyepiece system 10 according to a first embodiment of the present invention includes, in order from an object side to an image side along an optical axis I, an aperture stop a, a first lens element 1, a second lens element 2, a third lens element 3, and a fourth lens element 4. The object side refers to the side of the user's eyes, and the image side refers to the side of the display 9. The light beam emitted from the display 9 passes through the fourth lens 4, the third lens 3, the second lens 2, the first lens 1 and the aperture A in sequence, and then is received by the eyes of the user at the aperture A.

In the present embodiment, the first lens 1 to the fourth lens 4 are separated from each other without forming a cemented lens. Further, in the eye-distance adjustable eyepiece system 10, only the first lens 1 to the fourth lens 4 have refractive power, that is, only four lenses having refractive power.

Each of the first lens element 1, the second lens element 2, the third lens element 3, and the fourth lens element 4 includes an object- side surface 11, 21, 31, 41 facing the object side and passing the image forming light, and an image- side surface 12, 22, 32, 42 facing the image side and passing the image forming light.

The first lens 1 has a positive refractive power. The object-side surface 11 of the first lens element 1 is convex in the vicinity of the optical axis I, and the image-side surface 12 of the first lens element 1 is convex in the vicinity of the optical axis I. The second lens 2 has a positive refractive power. The object-side surface 21 of the second lens element 2 is convex in the vicinity of the optical axis I, and the image-side surface 22 of the second lens element 2 is convex in the vicinity of the optical axis I. The third lens 3 has a negative refractive power. The object-side surface 31 of the third lens element 3 is concave in the vicinity of the optical axis I, and the image-side surface 32 of the third lens element 3 is concave in the vicinity of the optical axis I. The fourth lens 4 has a positive refractive power. The object-side surface 41 of the fourth lens element 4 is convex in the vicinity of the optical axis I, and the image-side surface 42 of the fourth lens element 4 is concave in the vicinity of the optical axis I. In another embodiment, the image-side surface 32 of the third lens element 3 may be convex in the vicinity of the optical axis I. Correspondingly, the image side surface 12 of the first lens element 1 can be flat or concave in the vicinity of the optical axis I, and the object side surface 21 of the second lens element 2 can also be flat or concave in the vicinity of the optical axis I.

The first lens 1 has a refractive power suitable for controlling the field angle of the eyecup system 10. The second lens 2 has a positive refractive power which helps the first lens 1 to receive more light beams and correct spherical aberration. The third lens 3 has a negative refractive power, which is adapted to compensate for chromatic aberration (chromatic aberration). The second lens 2 having a positive refractive power, in cooperation with the third lens 3 having a negative refractive power, can reduce the Petzval sum (Petzval sum) of the eye-distance adjustable eyepiece system 10 and effectively correct curvature of field. The fourth lens element 4 has positive refractive power, and at least one of the object-side surface 41 and the image-side surface 42 is aspheric to facilitate distortion adjustment.

The first lens element 1 to the fourth lens element 4 are adapted to move together toward the object side or the image side according to the eye relief distance of the user. For example, when the eye (one of the user's eyes) at the aperture a has near vision, the first to fourth lenses 1 to 4 may be moved together toward the image side (i.e., toward the display 9), and when the eye at the aperture a has far vision, the first to fourth lenses 1 to 4 may be moved together toward the object side (i.e., toward the aperture a). It should be noted that the first lens 1 to the fourth lens 4 belong to the same lens group, and the distance between two lenses in the four lenses on the optical axis I is a fixed value. When there is a need to adjust the eye relief, the four lenses will move together and not individually.

By adjusting the positions of the four lenses between the aperture a and the display 9, the eye-fitted distance can be adjusted without changing the distance between the aperture a and the display 9, so that the eye-fitted distance adjustable eyepiece system 10 has a fixed size and a simplified assembly (without providing a mechanism for moving the display 9). In addition, since the eye distance adjusting eyepiece system 10 can adjust the eye distance according to the degree of myopia or hyperopia of the user's eyes, so that the user can see the image displayed on the display 9 clearly even with naked eyes, when the eye distance adjusting eyepiece system 10 is applied to the head-mounted display, the user does not need to wear additional vision correction devices (such as glasses). Thus, the wearing weight of the user can be reduced and the burden of long-term use can be reduced.

In order to satisfy the requirement of light weight, the first lens 1 to the fourth lens 4 can be made of plastic material. However, at least one of the first lens element 1 to the fourth lens element 4 may be made of glass. For example, the first lens 1 of the first embodiment may be made of a glass material.

The detailed optical parameters of the first embodiment are shown in tables one and two. In tables one and two, "D1" represents the distance from the magnified virtual image seen by the eye to the aperture a on the optical axis I. When D1 is positive, it means that aperture a is located between the enlarged virtual image and the image side (i.e., aperture a is closer to the image side than the enlarged virtual image). When D1 is negative, it indicates that the enlarged virtual image is located between aperture a and the image side (i.e., the enlarged virtual image is closer to the image side than aperture a). "D2" represents the distance from the aperture a to the object-side surface 11 of the first lens element 1 on the optical axis I, i.e., the eye relief. "D10" represents the distance on the optical axis I from the image-side surface 42 of the fourth lens element 4 to the display 9. In Table two, "(-2D)" diopters indicate distance vision of 200 degrees, and "(-8D)" diopters indicate near vision of 800 degrees. As can be seen from table two, in order to make the eyes clearly see the enlarged virtual image, in the case of hyperopia, the lens group (including the first lens element 1 to the fourth lens element 4) needs to move toward the aperture stop (i.e., shorten D2 and increase D10); in the case of myopia, the lens group must be moved towards the display 9 (i.e. increasing D2 and shortening D10).

In table one, a distance (mm) between the object-side surface 11 of the first lens element 1 and the image-side surface 12 of the first lens element 1 is 3.1019, which means that the distance between the object-side surface 11 of the first lens element 1 and the image-side surface 12 of the first lens element 1 on the optical axis I (i.e. the thickness of the first lens element 1 on the optical axis I) is 3.1019 mm. Similarly, a distance (mm) between the image-side surface 12 of the first lens element 1 and the object-side surface 21 of the second lens element 2 is 0.04mm, which means that the distance between the image-side surface 12 of the first lens element 1 and the object-side surface 21 of the second lens element 2 is 0.04mm on the optical axis I. The other fields of distance (mm) can be analogized and will not be repeated below.

Watch 1

Variable number	D1(mm)	D2(mm)	D10(mm)
				Diopter (+2D)	500	13.7	4.3
Diopter (-8D)	-125	16.5	1.5

Watch two

In this embodiment, the object-side surface 11 and the image-side surface 12 of the first lens element 1 are spherical surfaces. In addition, the object-side surface 12 and the image-side surface 22 of the second lens element 2, the object-side surface 31 and the image-side surface 32 of the third lens element 3, and the object-side surface 41 and the image-side surface 42 of the fourth lens element 4 are aspheric surfaces, and the aspheric surfaces are defined by the following formula (1):

in the formula (1), Y is a distance between a point on the aspherical surface curve and the optical axis I. Z is the depth of the aspheric surface. R is the radius of curvature of the lens surface near the optical axis I. K is the cone constant (conc constant). A. the_iAre the i-th order aspheric coefficients.

The aspheric coefficients of the object-side surface 21 of the second lens 2 to the image-side surface 42 of the fourth lens 4 in formula (1) are shown in table three. The column number 21 in table three indicates that it is the aspheric coefficient of the object-side surface 21 of the second lens element 2, and so on. Since the 2 nd order aspherical surface coefficient a2 and the 14 th order aspherical surface coefficient a14 of the six surfaces are both 0, they are not shown.

Surface of

K

A4

A6

A8

A10

A12

21

-1.022

-5.685E-05

5.830E-07

-9.529E-09

7.211E-11

-1.695E-13

22

0.3347

-7.191E-05

2.542E-06

-2.810E-09

-1.026E-10

2.569E-12

31

-5.409

5.940E-05

-3.379E-06

1.471E-08

3.014E-10

-6.903E-13

32

-0.01428

5.777E-04

-3.230E-06

-8.162E-08

-1.107E-10

1.435E-11

41

-6.055

2.594E-04

-4.390E-06

6.366E-08

-3.130E-09

3.640E-11

42

-124.4

8.860E-04

-1.319E-05

-9.810E-08

1.698E-09

1.923E-11

Watch III

In view of the unpredictability of the optical system design, under the framework of the present invention, at least one of the following conditional expressions is preferably satisfied to shorten the length of the system, increase the field angle, improve the imaging quality, or improve the manufacturing yield, thereby improving the drawbacks of the prior art.

High resolution can be achieved by satisfying 0.7< | Φ 3/(Φ 1+ Φ 2) | <4.5, where Φ 1 is the reciprocal of the focal length of the first lens 1, Φ 2 is the reciprocal of the focal length of the second lens 2, and Φ 3 is the reciprocal of the focal length of the third lens 3. When the refractive power of the first lens element 1 and the refractive power of the second lens element 2 are biased to the upper limit of the conditional expression, the Total Track Length (TTL) is too long. When the deviation is toward the lower limit of the conditional expression, the refractive power of the first lens element 1 and the second lens element 2 is too large, which makes it difficult to correct aberrations, especially Coma (Coma).

Correction of low-order aberrations is facilitated by satisfying 0< | R5/f3| <3.5, where R5 is the radius of curvature of the object-side surface 31 of the third lens 3, and f3 is the focal length of the third lens 3.

The ability to correct chromatic aberration is improved by satisfying | V2-V3| >20, where V2 is the Abbe number of the second lens element 2 and V3 is the Abbe number of the third lens element 3. Abbe number also known as Abbe number

By satisfying 1.5< TTL/D2<5.5, images with different diopters can be clearly resolved, wherein TTL is the distance from the aperture a to the display 9 on the optical axis I (i.e. the length of the system).

The relationship between the important parameters in the eye-distance adjustable eyepiece system 10 of the first embodiment is shown in table four. In table four, "D2 (+ 2D)" represents the distance on the optical axis I between the aperture a and the object-side surface 11 of the first lens element 1 when diopter is +2D, i.e., the eye relief distance when diopter is + 2D. "D2 (-8D)" represents the distance from the aperture a to the object-side surface 11 of the first lens element 1 on the optical axis I when diopter is-8D, i.e., the eye relief when diopter is-8D. Similarly, "TTL/D2 (+ 2D)" and "TTL/D2 (-8D)" represent TTL/D2 at +2D and-8D diopters, respectively.

Φ1	0.045166
		Φ2	0.076731
Φ3	-0.23451
		|Φ3/(Φ1+Φ2)|	1.9238
f3	-4.2643
		|R5/f3|	0.652159
|V2-V3|	26.134
		TTL	36.09
D2(+2D)	13.7
		D2(-8D)	16.5
TTL/D2(+2D)	2.69
		TTL/D2(-8D)	2.23

Watch four

Fig. 2 and 3 are field curvature aberration diagrams of the first embodiment of the adjustable eye distance eyepiece system with diopter values of +2D and-8D, respectively, which illustrate the astigmatic aberration in the sagittal (sagittal) direction and astigmatic aberration in the meridional (meridional) direction according to the first embodiment. Fig. 4 and 5 are distortion aberration diagrams of the eye-distance adjusting eyepiece system of the first embodiment when the diopter is +2D and-8D. Fig. 6A to 6F and fig. 7A to 7F are horizontal beam fan diagrams when the diopter of the eye-distance adjustable eyepiece system of the first embodiment is +2D and-8D, respectively. The graphs shown in fig. 2 to 7F are all within the standard range, and thus it can be verified that the eye-fitted distance adjustable eyepiece system 10 of the first embodiment has good imaging quality.

As described above, compared to the conventional display, the eye-distance adjustable eyepiece system 10 of the first embodiment can have a large field angle, good imaging quality, and adjustable eye-distance.

Fig. 8A and 8B are schematic diagrams illustrating an eye-distance adjustable eyepiece system according to a second embodiment of the invention with diopters of +2D and-8D respectively. Referring to fig. 8A and 8B, a second embodiment of the eye-distance adjustable eyepiece system 10 of the present invention is substantially similar to the first embodiment. The main differences are: the optical data, aspherical coefficients, and parameters of these lenses (the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4) are more or less different. Further, the first lens 1 has a negative refractive power. The object-side surface 11 of the first lens 1 is concave in the vicinity of the optical axis I, and the image-side surface 12 of the first lens 1 is concave in the vicinity of the optical axis I. The image-side surface 32 of the third lens element 3 is convex in the vicinity of the optical axis I. The image-side surface 42 of the fourth lens element 4 is convex in the vicinity of the optical axis I. The object-side surface 11 and the image-side surface 12 of the first lens element 1 are both aspheric.

The detailed optical parameters of the second embodiment of the eye-distance adjustable eyepiece system 10 are shown in table five and table six. The aspheric coefficients of the terms in the formula (1) from the object-side surface 11 of the first lens 1 to the image-side surface 42 of the fourth lens 4 of the second embodiment are shown in table seven. The relationship between the important parameters in the eye-distance adjustable eyepiece system 10 of the second embodiment is shown in table eight.

Watch five

Variable number	D1(mm)	D2(mm)	D10(mm)
				Diopter (+2D)	500	13.3	6.9
Diopter (-8D)	-125	17.2	3

Watch six

Surface of

K

A4

A6

A8

A10

A12

A14

11

35.49168

6.16E-04

-5.81E-06

1.48E-08

3.74E-10

-3.88E-12

1.51E-14

12

-102.997

4.39E-04

-6.77E-06

3.07E-08

5.45E-11

9.30E-13

-2.06E-14

21

-0.83988

-2.41E-04

2.51E-06

-1.33E-08

-3.99E-11

9.58E-13

-3.33E-15

22

1.727095

-8.50E-05

5.53E-06

-6.60E-09

-1.83E-10

-1.23E-12

1.10E-14

31

-2.06346

1.82E-04

1.41E-06

-1.60E-08

5.26E-11

-5.45E-13

3.67E-15

32

-6.95947

1.63E-04

-2.19E-06

3.27E-08

-2.17E-10

1.25E-12

-9.53E-15

41

-3.99564

4.37E-04

-6.32E-06

8.98E-08

-9.82E-10

6.79E-12

-2.40E-14

42

-100.037

7.08E-04

-1.09E-05

1.06E-07

-2.68E-10

-6.35E-12

5.36E-14

Watch seven

Table eight

Fig. 9 and 10 are field curvature aberration diagrams when the diopter scale of the eye-fitted distance adjustable eyepiece system of the second embodiment is +2D and-8D, respectively. FIGS. 11 and 12 are distortion aberration diagrams when the diopter scale of the eye-distance adjustable eyepiece system of the second embodiment is +2D and-8D. Fig. 13A to 13F and fig. 14A to 14F are horizontal beam fan diagrams when the diopter of the eye-distance adjustable eyepiece system of the second embodiment is +2D and-8D, respectively. The graphs shown in fig. 9 to 14F are all within the standard range, and thus it can be verified that the eye-fitted distance adjustable eyepiece system 10 of the second embodiment has good imaging quality.

As described above, the eye-distance adjustable eyepiece system 10 of the second embodiment can have a large field angle, good imaging quality, and adjustable eye-distance compared to the conventional display.

Fig. 15A and 15B are schematic diagrams illustrating an eye-distance adjustable eyepiece system according to a third embodiment of the invention with diopters of +2D and-8D respectively. Referring to fig. 15A and 15B, a third embodiment of the eye-distance adjustable eyepiece system 10 of the present invention is substantially similar to the second embodiment. The main differences are: the optical data, aspherical coefficients, and parameters of these lenses (the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4) are more or less different.

Detailed optical parameters of the eye-distance adjustable eyepiece system 10 of the third embodiment are shown in table nine and table ten. Each aspheric coefficient in the formula (1) from the object-side surface 11 of the first lens 1 to the image-side surface 42 of the fourth lens 4 of the third embodiment is shown in table eleven. The relationship between the important parameters in the eye-distance adjustable eyepiece system 10 of the third embodiment is shown in table twelve.

Watch nine

Variable number	D1(mm)	D2(mm)	D10(mm)
				Diopter (+2D)	500	13.3	6.45
Diopter (-8D)	-125	17.2	2.55

Watch ten

Surface of

K

A4

A6

A8

A10

A12

A14

11

-47.7103

6.69E-04

-7.26E-06

-3.71E-09

5.11E-10

-1.84E-12

-6.96E-15

12

-998.237

0.000492

-6.37E-06

-9.06E-10

1.94E-10

1.34E-12

-1.56E-14

21

-0.58362

-3.14E-04

1.62E-06

-1.52E-08

-4.57E-12

9.10E-13

-5.57E-15

22

-0.61055

1.18E-04

2.06E-06

-4.17E-10

-7.86E-11

-9.22E-13

7.99E-15

31

-2.35626

1.63E-04

1.84E-07

-4.78E-09

2.17E-11

-9.43E-13

6.64E-15

32

-95.6973

2.48E-04

-1.94E-07

1.18E-09

-1.50E-10

1.06E-12

-3.01E-15

41

-3.977

2.20E-04

-2.40E-06

6.68E-08

-1.20E-09

1.10E-11

-4.47E-14

42

59.92065

5.73E-04

-7.14E-06

6.82E-08

5.65E-11

-8.28E-12

4.29E-14

Watch eleven

Φ1	-0.01662
		Φ2	0.09258
Φ3	-0.23442
		|Φ3/(Φ1+Φ2)|	3.08602
f3	-4.265
		|R5/f3|	0.46821
|V2-V3|	26.2
		TTL	45.95
D2(+2D)	13.3
		D2(-8D)	17.2
TTL/D2(+2D)	3.45
		TTL/D2(-8D)	2.67

Watch twelve

Fig. 16 and 17 are field curvature aberration diagrams when the diopter scale of the eye-fitted distance adjustable eyepiece system of the third embodiment is +2D and-8D, respectively. Fig. 18 and 19 are distortion aberration diagrams when the diopter scale of the eye-distance adjustable eyepiece system of the third embodiment is +2D and-8D. Fig. 20A to 20F and fig. 21A to 21F are transverse beam fan diagrams when the diopter of the eye-distance adjustable eyepiece system of the third embodiment is +2D and-8D, respectively. The graphs shown in fig. 16 to 21F are all within the standard range, and it can be verified that the eye-relief adjustable eyepiece system 10 of the third embodiment has good imaging quality.

As described above, the eye-distance adjustable eyepiece system 10 of the third embodiment can have a large field angle, good imaging quality, and adjustable eye-distance compared to the conventional display.

Fig. 22A and 22B are schematic diagrams illustrating an eye-distance adjustable eyepiece system according to a fourth embodiment of the invention with diopters of +2D and-8D respectively. Referring to fig. 22A and 22B, a fourth embodiment of the eye-distance adjustable eyepiece system 10 of the present invention is substantially similar to the third embodiment. The main differences are: the optical data, aspherical coefficients, and parameters of these lenses (the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4) are more or less different. The object-side surface 11 of the first lens element 1 is convex in the vicinity of the optical axis I. The image-side surface 22 of the second lens element 2 is concave in the vicinity of the optical axis I. The image-side surface 42 of the fourth lens element 4 is concave in the vicinity of the optical axis I.

Detailed optical parameters of the eye-distance adjustable eyepiece system 10 of the fourth embodiment are shown in table thirteen and table fourteen. Each aspheric coefficient in the formula (1) from the object-side surface 11 of the first lens 1 to the image-side surface 42 of the fourth lens 4 of the fourth embodiment is as shown in table fifteen. The relationships between the important parameters in the eye-distance adjustable eyepiece system 10 of the fourth embodiment are shown in table sixteen.

Watch thirteen

Variable number	D1(mm)	D2(mm)	D10(mm)
				Diopter (+2D)	500	14.5	7.7
Diopter (-8D)	-125	18.1	3.9

Table fourteen

Surface of

K

A4

A6

A8

A10

A12

A14

11

1.7130

3.20E-04

-9.84E-08

-2.33E-07

5.36E-09

-5.60E-11

2.85E-13

12

-0.9348

-0.00102

4.78E-05

-1.24E-06

1.67E-08

-1.26E-10

5.03E-13

21

-1.1688

-0.00115

2.96E-05

-4.25E-07

3.23E-09

-1.34E-11

3.96E-14

22

0.5688

-0.00086

-2.75E-05

1.47E-06

-2.75E-08

2.65E-10

-1.32E-12

31

-8.9628

0.001348

-4.99E-05

9.63E-07

-1.04E-08

5.98E-11

-1.65E-13

32

-99

0.001079

1.88E-06

-1.09E-06

3.07E-08

-3.96E-10

2.49E-12

41

-3.1571

7.55E-04

-1.34E-05

-7.09E-08

5.44E-09

-7.99E-11

5.51E-13

42

-41.5911

0.001689

-3.01E-05

-3.49E-07

2.28E-08

-3.80E-10

2.80E-12

Fifteen items of table

Φ1	-0.031
		Φ2	0.0667
Φ3	-0.0702
		|Φ3/(Φ1+Φ2)|	1.9621
f3	-14.2367
		|R5/f3|	0.41
|V2-V3|	33.8
		TTL	45
D2(+2D)	14.5
		D2(-8D)	18.1
TTL/D2(+2D)	3.1
		TTL/D2(-8D)	2.48

Watch sixteen

FIGS. 23 and 24 are graphs of curvature of field aberration for the diopters +2D and-8D of the eye-fitted distance adjustable eyepiece system of the fourth embodiment. FIGS. 25 and 26 are distortion aberration diagrams when the diopter scale of the eye-distance adjustable eyepiece system of the fourth embodiment is +2D and-8D. Fig. 27A to 27F and fig. 28A to 28F are transverse beam fan diagrams at diopter +2D and-8D of the eye-distance adjustable eyepiece system of the fourth embodiment, respectively. Fig. 23 to 28F show graphs within a standard range, and it can be verified that the eye-relief adjustable eyepiece system 10 of the fourth embodiment has good imaging quality.

As described above, the eye-distance adjustable eyepiece system 10 of the fourth embodiment can have a large field angle, good imaging quality, and adjustable eye-distance compared to the conventional display.

In summary, the ocular distance adjustable eyepiece system of the embodiment of the invention can achieve the following effects and advantages: by means of the design and arrangement of the concave-convex shapes of the object side surface or the image side surface of the four lenses, the eye-distance-adaptive adjustable eyepiece system has a large field angle, good imaging quality and adjustable eye distance. Further, the first lens has a refractive power adapted to control a field angle of the eyespot adjustable eyepiece system. The second lens has a positive refractive power, which helps the first lens to receive more light and correct spherical aberration. The third lens has a negative refractive power adapted to compensate for chromatic aberration. The second lens with positive refractive power is matched with the third lens with negative refractive power, so that the Petzval sum of the eye-distance-adaptive adjustable eyepiece system can be reduced, and the curvature of field can be effectively corrected. The fourth lens has positive refractive power, and at least one of the object side surface and the image side surface of the fourth lens is aspheric, so that the distortion can be favorably adjusted. By adjusting the positions of the four lenses between the aperture and the display, the eye-fitting distance can be adjusted without changing the distance between the aperture and the display, so that the eye-fitting distance adjustable eyepiece system has a fixed size and is simple to assemble. In addition, the eye distance adjusting eyepiece system can adjust the eye distance according to the degree of myopia or hyperopia of the eyes of the user, so that the user can see the image displayed by the display clearly under the condition of naked eyes, and when the eye distance adjusting eyepiece system is applied to the head-mounted display, the user does not need to wear an additional vision correction device. Thus, the wearing weight of the user can be reduced and the burden of long-term use can be reduced. When the requirement of 0.7< | Φ 3/(Φ 1+ Φ 2) | <4.5 is satisfied, high resolution can be achieved. When 0< | R5/f3| <3.5 is satisfied, correction of low-order aberration is facilitated. When the condition of V2-V3| >20 is satisfied, the capability of correcting chromatic aberration can be improved. When 1.5< TTL/D2<5.5 is satisfied, images with different diopters can be clearly analyzed. In addition, the aspheric lens is used for replacing the free-form surface lens, so that the difficulty in design and manufacture can be simplified, and the cost and the manufacturing tolerance can be reduced.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (9)

1. An eye-distance adjustable eyepiece system, comprising, in order along an optical axis from an object side to an image side, an aperture stop, a first lens element having refractive power, a second lens element having positive refractive power, a third lens element having negative refractive power, and a fourth lens element having positive refractive power, wherein the first lens element to the fourth lens element are adapted to move together toward the object side or the image side according to an eye distance of a user, and the first lens element to the fourth lens element each comprise an object side surface facing the object side and passing an imaging light ray therethrough and an image side surface facing the image side and passing an imaging light ray therethrough, the eye-distance adjustable eyepiece system satisfying:

0<|R5/f3|<3.5；

wherein R5 is the radius of curvature of the object-side surface of the third lens, and f3 is the focal length of the third lens;

the object-side surface of the second lens element is convex in a region near the optical axis, at least one of the object-side surface and the image-side surface of the second lens element is aspheric, the object-side surface of the third lens element is concave in a region near the optical axis, at least one of the object-side surface and the image-side surface of the third lens element is aspheric, the object-side surface of the fourth lens element is convex in a region near the optical axis, and at least one of the object-side surface and the image-side surface of the fourth lens element is aspheric.

2. The eye-set adjustable eyepiece system of claim 1, further satisfying:

0.7<|Φ3/(Φ1+Φ2)|<4.5；

where Φ 1 is an inverse of a focal length of the first lens, Φ 2 is an inverse of a focal length of the second lens, and Φ 3 is an inverse of a focal length of the third lens.

3. The eye-set adjustable eyepiece system of claim 1, further satisfying:

|V2-V3|>20；

wherein V2 is the Abbe number of the second lens and V3 is the Abbe number of the third lens.

4. The eye-set adjustable eyepiece system of claim 1, further satisfying:

1.5<TTL/D2<5.5；

wherein TTL is a distance on the optical axis from the aperture stop to a display, and D2 is a distance on the optical axis from the aperture stop to the object-side surface of the first lens.

5. The eye system of claim 1, wherein the refractive power of the first lens is positive, the object-side surface of the first lens is convex in a region near the optical axis, the image-side surface of the second lens is convex in a region near the optical axis, and the image-side surface of the fourth lens is concave in a region near the optical axis.

6. The eye-distance adjustable eyepiece system of claim 1, wherein the refractive power of the first lens is negative, the image side surface of the first lens is concave in a region near the optical axis, and the image side surface of the third lens is convex in a region near the optical axis.

7. The eye-distance adjustable eyepiece system of claim 6, wherein the object-side surface of the first lens element is concave in the vicinity of the optical axis, the image-side surface of the second lens element is convex in the vicinity of the optical axis, and the image-side surface of the fourth lens element is convex in the vicinity of the optical axis.

8. The eye-distance adjustable eyepiece system of claim 6, wherein the object-side surface of the first lens element is convex in the vicinity of the optical axis, the image-side surface of the second lens element is concave in the vicinity of the optical axis, and the image-side surface of the fourth lens element is concave in the vicinity of the optical axis.

9. The eye-distance adjustable eyepiece system of claim 1, wherein the object-side surface and the image-side surface of each of the second lens, the third lens and the fourth lens are aspheric.

Images