TWI597522B - Magnified lens set for virtual reality - Google Patents

Description

Magnifying lens group for virtual reality

The present invention relates to a lens assembly, and more particularly to a magnifying lens group for virtual reality.

Virtual Reality (VR) is a virtual world that uses computer simulation to generate a three-dimensional space, providing users with a simulation of the senses such as vision, making the user feel as if they are immersed.

A Head Mount Display (HMD) is an image display that is worn on the user's head to provide a visually realistic visual presentation platform device for virtual reality. The head-mounted display mainly places a small-sized display element in front of the user's eyes in the form of glasses or a helmet, and projects an image displayed by the display element to the user's eyes through an optical lens group at a close distance.

However, the above optical lens group must be capable of magnifying the image of the display element and generating a wider viewing angle image projection for the user's eyes at a larger angle of view, covering as much as possible the range of the field of view of the user's eyes, and The optical lens assembly described above must also have good image quality, so that the image projected into the user's eyes can be simulated closer to the environmental image actually received by the eye, so that the visual experience of the user can be improved.

According to the above description, how to produce an optical lens group required for a head-mounted display for virtual reality and to continuously improve its image quality has long been a target pursued by the industry, the official, and the academic community.

Accordingly, it is an object of the present invention to provide a magnifying lens group for a virtual reality having a wide angle of view, effective correction of system aberrations, and correction of system chromatic aberration.

Therefore, the magnifying lens group for virtual reality of the present invention sequentially includes an aperture stop, a first lens, a second lens, and a third lens along an optical axis from the object side to the image side.

The first lens has a positive refractive power and includes an object side that faces the object side and passes imaging light and an image side that faces the image side and passes imaging light. The image side surface of the first lens is a convex surface that is convex toward the image side.

The second lens has a negative refractive power and includes an object side that faces the object side and passes imaging light and an image side that faces the image side and allows imaging light to pass.

The third lens has a negative refractive power and includes an object side facing the object side and passing the imaging light and an image side facing the image side and passing the imaging light. The image side surface of the third lens is an aspherical convex surface convex toward the image side and has at least one inflection point from the optical axis to the aspheric end point.

Wherein, the magnifying lens group satisfies 0.26<f1/f<0.65, 0.57<|f2|/f<2.29, 0.36<|f3|/f<0.77, and FOV>100 ̊, f1 is the focal length of the first lens, f2 For the focal length of the second lens, f3 is the focal length of the third lens, f is the total focal length of the system of the magnifying lens group, and FOV is the total field of view of the system of the magnifying lens group.

The effect of the present invention is that the first lens has a positive refractive power and a side surface thereof is a convex surface, the second lens has a negative refractive power, and the third lens has a negative refractive power and a lens refractive power of the convex side of the image side. When the relationship between the optical parameters of the magnifying lens group satisfies the above conditional expression, the magnifying lens group for virtual reality of the present invention can effectively correct system aberrations and achieve a wider system total view. The purpose of the field corner.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 1, a first embodiment of a magnifying lens group for virtual reality according to the present invention includes an aperture stop 10, a first lens 1, and a second along an optical axis I from the object side to the image side. The lens 2, a third lens 3, and a protective glass sheet 4. In addition, in order to meet the demand for light weight of the product, the first lens 1, the second lens 2, and the third lens 3 are all made of a plastic material, but the first lens 1, the second lens 2, and the first The material of the three lenses 3 is not limited thereto.

The first lens 1 has a positive refractive power and includes an object side 11 facing the object side and passing imaging light, and an image side surface 12 facing the image side and passing imaging light. The object side surface 11 of the first lens 1 is a convex surface on the convex object side, and the image side surface 12 of the first lens 1 is a convex surface convex toward the image side. The focal length of the first lens 1 is 17.720 mm, and the Abbe number of the first lens 1 is 56.

The second lens 2 has a negative refractive power and includes an object side 21 facing the object side and passing the imaging light, and an image side 22 facing the image side and passing the imaging light. The object side surface 21 of the second lens 2 is a concave surface on the concave object side, and the image side surface 22 of the second lens 2 is a convex surface convex toward the image side. The focal length of the second lens 2 is -62.2120 mm, and the Abbe number of the second lens 2 is 56.

The third lens 3 has a negative refractive power and includes an object side 31 facing the object side and passing the imaging light, and an image side 32 facing the image side and passing the imaging light. The object side surface 31 of the third lens 3 is a concave surface on the concave object side, and the image side surface 32 of the third lens 3 is an aspherical convex surface on the convex image side and has a point from the optical axis I to the aspheric end point. The inflection point, but not limited to this, can also have more than two inflection points depending on the unevenness. The focal length of the third lens 3 is -20.9150 mm, and the Abbe number of the third lens 3 is 22.4.

The protective glass sheet 4 does not have a refractive power and includes an object side surface 41 that faces the object side and allows imaging light to pass therethrough, and an image side surface 42 that faces the image side and allows imaging light to pass therethrough.

In this embodiment, a display screen 100 for a virtual reality head mounted display is disposed on the image side of the protective glass sheet 4, and a user's eyes (not shown) are located in the magnifying lens group. The object side, that is, adjacent to the aperture stop 10 is located.

In the present embodiment, only the above lens has a refractive power. The other detailed optical data of the first embodiment is shown in FIG. 3, and the effective focal length (EFL) of the magnifying lens group of the first embodiment is 35.3578 mm, and the total field of view of the system (field) The view, referred to as FOV, is 125 ∘, the system length is 58.604 mm, and the aperture value (Fno) of the aperture stop 10 is 4.4. The system length of the magnifying lens group refers to the distance between the aperture stop 10 and the display screen 100 on the optical axis I.

The first lens 1, the second lens 2, and the object side faces 11, 21, 31 and the image side faces 12, 22, 32 of the third lens 3 are aspherical in total, and the non-spherical surface is according to the following formula definition:

-----------(1)

among them:

Y: the distance between the point on the aspheric curve and the optical axis I;

Z: the depth of the aspherical surface (the point on the aspherical surface from which the optical axis I is Y, and the tangent plane tangent to the vertex on the aspherical optical axis I, the vertical distance between the two);

R: radius of curvature of the surface of the lens;

K: cone constant (conic constant);

: 2ith order aspheric coefficient.

The first lens 1, the second lens 2, and the object side faces 11, 21, 31 and the image side faces 12, 22, 32 of the third lens 3 have a taper coefficient and various aspheric coefficients in the formula (1) As shown in Figure 4.

Referring to Fig. 2, the diagram of (a) illustrates the longitudinal spherical aberration of the first embodiment, and the patterns of (b) and (c) respectively illustrate the sagittal of the first embodiment. The astigmatism aberration of the direction and the astigmatic aberration in the tangential direction, and the pattern of (d) illustrate the distortion aberration of the first embodiment. In the longitudinal spherical aberration diagram of the first embodiment, in Fig. 2(a), the curves formed by each of the wavelengths are close to each other and are close to the middle, indicating that the off-axis rays of different heights of each wavelength are concentrated near the imaging point. It can be seen from the deflection amplitude of the curve of each wavelength that the imaging point deviation of the off-axis rays of different heights is controlled within the range of -0.4 mm to +0.6 mm, so this embodiment does significantly improve the spherical aberration of the same wavelength, The distances between the three representative wavelengths are also relatively close to each other, and the imaging positions representing the different wavelengths of light are already concentrated, so that the chromatic aberration is also significantly improved.

In the two astigmatic aberration diagrams of Figs. 2(b) and 2(c), the amount of change in the focal length of the astigmatic aberration in the sagittal direction over the entire field of view falls within ±2.0 mm, and the meridian The amount of change in the focal length of the astigmatic aberration of the direction within a field of view below a large angle falls within ±2.0 mm, indicating that the optical system of the first embodiment can effectively correct the aberration. The distortion aberration diagram of FIG. 2(d) shows that the distortion aberration of the first embodiment is maintained in the range of -50% to 0%, indicating that the distortion aberration of the first embodiment has been consistent with the optical system. The image quality requirements, so the first embodiment can maintain good optical performance under the condition of expanding the total viewing angle of the system to meet the optical condition requirements of the headband display for virtual reality.

Referring to FIG. 5, a second embodiment of a magnifying lens group for virtual reality according to the present invention is substantially similar to the first embodiment except for each optical data, a cone coefficient, each aspheric coefficient, and between components. The spacing parameters are somewhat different.

The focal length of the first lens 1 is 13.8850 mm, the Abbe number of the first lens 1 is 56, the focal length of the second lens 2 is -30.4890 mm, and the Abbe number of the second lens 2 is 56, the third The focal length of the lens 3 is -18.5750 mm, and the Abbe number of the third lens 3 is 22.4.

The other detailed optical and inter-element spacing parameter data of the second embodiment is shown in FIG. 7, and the total focal length of the system of the magnifying lens group of the second embodiment is 35.9746 mm, and the total viewing angle of the system is 120 ∘. The system length is 67.838 mm, and the aperture value (Fno) of the aperture diaphragm 10 is 4.49.

The first lens 1 of the second embodiment, the second lens 2, and the object side faces 11, 21, 31 of the third lens 3 and the image side faces 12, 22, 32 have a taper coefficient in the formula (1) And various aspherical coefficients are shown in Figure 8.

Referring to FIG. 6, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), (c), and the distortion aberration diagram of (d) that the second embodiment can also maintain good optical performance. .

Referring to FIG. 9, a third embodiment of a magnifying lens group for virtual reality according to the present invention is substantially similar to the first embodiment, except for each optical data, a cone coefficient, each aspheric coefficient, and between components. The spacing parameters are somewhat different.

The focal length of the first lens 1 is 13.9302 mm, the Abbe number of the first lens 1 is 56, the focal length of the second lens 2 is -31.8170 mm, and the Abbe number of the second lens 2 is 56. The focal length of the lens 3 is -19.3110 mm, and the Abbe number of the third lens 3 is 30.5.

The other detailed optical and inter-element spacing parameter data of the third embodiment is as shown in FIG. 11, and the total focal length of the system of the magnifying lens group of the third embodiment is 36.1157 mm, and the total viewing angle of the system is 120 ∘. The system length is 68.262 mm, and the aperture value (Fno) of the aperture diaphragm 10 is 4.51.

The first lens 1 of the third embodiment, the second lens 2, and the object side faces 11, 21, 31 of the third lens 3 and the image side faces 12, 22, 32 have a taper coefficient in the formula (1) And the aspherical coefficients are shown in Figure 12.

Referring to Fig. 10, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), (c), and the distortion aberration diagram of (d) that the third embodiment can also maintain good optical performance. .

Referring to FIG. 13, a fourth embodiment of a magnifying lens group for virtual reality according to the present invention is substantially similar to the first embodiment except that each optical data, a taper coefficient, each aspherical coefficient, and between components are The spacing parameters are somewhat different.

The focal length of the first lens 1 is 13.3880 mm, the Abbe number of the first lens 1 is 56, the focal length of the second lens 2 is -29.4270 mm, and the Abbe number of the second lens 2 is 56, the third The focal length of the lens 3 is -18.8640 mm, and the Abbe number of the third lens 3 is 30.5.

The other detailed optical and inter-element spacing parameter data of the fourth embodiment is as shown in FIG. 15, and the total focal length of the system of the magnifying lens group of the fourth embodiment is 36.0273 mm, and the total viewing angle of the system is 120 ∘. The system length is 67.932 mm, and the aperture value (Fno) of the aperture diaphragm 10 is 4.5.

The first lens 1 of the fourth embodiment, the second lens 2, and the object side faces 11, 21, 31 of the third lens 3 and the image side faces 12, 22, 32 have a taper coefficient in the formula (1) And the various aspherical coefficients are shown in Figure 16.

Referring to Fig. 14, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), (c), and the distortion aberration diagram of (d) that the fourth embodiment can also maintain good optical performance. .

Referring to FIG. 17, which is a table diagram of optical parameters of the above four embodiments, the magnifying lens group for virtual reality of the present invention has a positive refractive power through the first lens 1 and a side surface 12 thereof is convex, and the second The lens 2 has a negative refractive power, and the third lens 3 has a negative refractive power and a lens refractive power and a surface structure configuration in which the image side surface 32 is convex, and the relationship between the optical parameters of the magnifying lens group satisfies the following conditions. In the formula, the magnifying lens group for the virtual reality of the present invention can effectively correct the system aberration while achieving the purpose of having a wider system total field of view: 0.26<f1/f<0.65, 0.57<|f2|/f<2.29 And 0.36<|f3|/f<0.77, where f1 is the focal length of the first lens 1, f2 is the focal length of the second lens 2, f3 is the focal length of the third lens 3, and f is the magnifying lens group The total focal length of the system.

When f1/f is less than the above endpoint value, the larger the aberration, especially the field curvature and astigmatism. When f1/f is greater than the above-mentioned endpoint value, the shorter the distance between the aperture stop 10 and the first lens 1, the easier the contact with the first lens 1 is due to the use of the upper eye, causing discomfort. When |f2|/f is smaller than the above endpoint value, the larger the aberration, the more serious the spherical aberration, coma, field curvature and astigmatism are. When |f2|/f is larger than the above endpoint value, the f1/f problem will occur as the matching relationship of the total focal length f of the system increases, and the above f1/f problem occurs. When |f3|/f is smaller than the above-mentioned endpoint value, the larger the aberration, especially the more uneven the color difference from the optical axis on the optical axis. When |f3|/f is larger than the above endpoint value, due to the matching relationship of the total focal length f of the system, f1/f also increases, and the above f1/f problem occurs.

In addition, the third lens 3 has a high dispersion (low Abbe number), that is, when the Abbe number of the third lens 3, the first lens 1 and the second lens 2 satisfies the following conditional expression, The magnifying lens group for inventing the virtual reality can effectively correct the system color difference: 20<V1-V3<40 and 20<V2-V3<40, wherein V1 is the Abbe number of the first lens 1, and V2 is the second The Abbe number of the lens 2, V3 is the Abbe number of the third lens 3. When V1-V3 or V2-V3 is less than the above endpoint value, the system chromatic aberration of the magnifying lens group may be insufficiently corrected. When V1-V3 or V2-V3 is greater than the above endpoint value, the system chromatic aberration of the magnifying lens group is overcorrected.

As apparent from the above description, the magnifying lens group for virtual reality of the present invention can achieve the object of the present invention.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the equivalent equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still The scope of the invention is covered.

10‧‧‧ aperture diaphragm
100‧‧‧ display screen
1‧‧‧first lens
11‧‧‧ ‧ side
12‧‧‧like side
2‧‧‧second lens
21‧‧‧ ‧ side
22‧‧‧like side
3‧‧‧ third lens
31‧‧‧ ‧ side
32‧‧‧like side
4‧‧‧Protective glass
I‧‧‧ optical axis

Other features and effects of the present invention will be apparent from the following description of the drawings. FIG. 1 is a schematic diagram of a lens configuration of a first embodiment of a magnifying lens group for virtual reality of the present invention; It is a longitudinal spherical aberration, an astigmatic field curvature curve and a distortion aberration diagram of the first embodiment; FIG. 3 is a table diagram showing optical data of each lens of the first embodiment; FIG. 4 is a table diagram illustrating the FIG. 5 is a schematic view showing a lens configuration of a second embodiment of the magnifying lens group for virtual reality of the present invention; FIG. 6 is a longitudinal view of the second embodiment; FIG. 7 is a table diagram showing optical data of each lens of the second embodiment; FIG. 8 is a table showing the lenses of the second embodiment; FIG. 9 is a schematic view showing a lens arrangement of a third embodiment of the magnifying lens group for virtual reality of the present invention; FIG. 10 is a longitudinal spherical aberration and astigmatic field curvature curve of the third embodiment; Distortion aberration diagram; Figure 11 is FIG. 12 is a table diagram illustrating the taper coefficient and the aspherical coefficient of each lens of the third embodiment; FIG. 13 is a virtual reality for the present invention. FIG. 14 is a longitudinal spherical aberration, an astigmatic field curvature curve and a distortion aberration diagram of the fourth embodiment; FIG. 15 is a table diagram illustrating the fourth implementation; FIG. 16 is a table showing a tapered coefficient and an aspherical coefficient of each lens of the fourth embodiment; and FIG. 17 is a table showing an enlargement of the virtual reality of the present invention. The optical parameters of this first embodiment to the fourth embodiment of the lens group.

10‧‧‧ aperture diaphragm

22‧‧‧like side

100‧‧‧ display screen

3‧‧‧ third lens

1‧‧‧first lens

31‧‧‧ ‧ side

11‧‧‧ ‧ side

32‧‧‧like side

12‧‧‧like side

4‧‧‧Protective glass

2‧‧‧second lens

I‧‧‧ optical axis

21‧‧‧ ‧ side

Claims (3)

A magnifying lens group for virtual reality, comprising an aperture diaphragm, a first lens, a second lens, and a third lens sequentially along an optical axis from the object side to the image side; the first lens a positive refractive power and includes a side of the object facing the object side and passing the imaging light and an image side facing the image side and passing the imaging light, the image side of the first lens being a convex surface convex toward the image side; a lens having a negative refractive power and including a side of the object facing the object side and passing the imaging light and an image side facing the image side and passing the imaging light; the third lens having a negative refractive power and including an object side a side surface of the object through which the imaging light passes and an image side surface facing the image side and passing the imaging light, the image side of the third lens being an aspheric convex surface convex toward the image side and having at least a point from the optical axis to the aspheric end point An inflection point; wherein the magnifying lens group satisfies 0.26<f1/f<0.65, 0.57<|f2|/f<2.29, 0.36<|f3|/f<0.77, and FOV>100 ̊, f1 is the first The focal length of the lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens The distance f is the total focal length of the system of the magnifying lens group, and the FOV is the total field of view of the system of the magnifying lens group. The magnifying lens group for virtual reality according to claim 1 further satisfies 20<V1 - V3<40, wherein V1 is the Abbe number of the first lens, and V3 is the Abbe number of the third lens. The magnifying lens group for virtual reality according to claim 1 further satisfies 20<V2-V3<40, wherein V2 is the Abbe number of the second lens, and V3 is the Abbe number of the third lens.