Projection optical system and head-mounted display

Abstract

Provided are: a projection optical system which is compact, has a wide field angle and a high resolution, and has high image-quality lens performance over the entire screen of a projection image; and a head-mounted display using the projection optical system. This projection optical system comprises a first lens which has positive refractive power, a second lens which has a concave shape on the projection surface side, a third lens which has a concave shape and in which the projection surface side is aspherical, a fourth lens which has positive refractive power, and a fifth lens which has negative refractive power and in which the image display element side is aspherical. The projection optical system satisfies 0.1<STP / TTL<0.18, 0.47<Fb / f<0.69, and 1.75<f3 / f<2.31. Here, TTL represents the total length of the projection optical system, STP represents the interval between the aperture stop and the projection surface of the first lens, f represents the focal length of the entire projection optical system, f3 represents the focal length of the third lens, and Fb represents the interval between the image display element-side surface of the fifth lens and the image display element.

Description

Projection optical system and head-mounted display

[0001] The present invention relates to a projection optical system and a head-mounted display.

[0002] In recent years, head-mounted displays (HMDs) have been put to practical use as head-mounted wearable devices for AR (Augmented Reality). These head-mounted displays are equipped with a projection optical system that enlarges and projects an image emitted from an image display element such as an LCD (Liquid Crystal Display) onto the position of a viewer's eyes (see, for example, Patent Document 1).

[0003] Special Publication No. 2021-536023

[0004] Such head-mounted displays are required to be compact, have a wide viewing angle, and have high image quality, and to meet these requirements, the optical system installed in them is also required to be compact, have a wide viewing angle, have high resolution, and have lens performance that provides high image quality across the entire screen, from the center to the periphery of the projected image.

[0005] An object of the present invention is to provide a projection optical system that is compact, has a wide angle of view, high resolution, and lens performance that provides high image quality across the entire screen of a projected image, and a head-mounted display that uses this projection optical system.

[0006] The projection optical system described in claim 1 is a projection optical system that projects an image from an image display element onto a projection surface, and is characterized in that it comprises, in order from the projection surface side, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and a concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical concave surface facing the image display element, and has a projection angle of view (FOV) of 60° or more and satisfies the following conditional expression: 0.1<STP / TTL<0.18 (1) 0.47<Fb / f<0.69 (2) 1.75<f3 / f<2.31 (3) Here, TTL is the total length of the projection optical system, STP is the distance between the aperture stop and the projection surface of the first lens, f is the focal length of the entire projection optical system, f3 is the focal length of the third lens, and Fb is the distance between the surface of the fifth lens facing the image display element and the image display element.

[0007] It is preferable that the projection optical system described in claim 2, in addition to the projection optical system described in claim 1, satisfies the following condition: 0.029<SAGΔR6 / f<0.15 (4), where SAGΔR6 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the third lens on the projection surface side and the amount of sag at the effective maximum position when the aspherical surface of the third lens on the projection surface side is a paraxial spherical surface defined by the paraxial radius of curvature.

[0008] It is preferable that the projection optical system described in claim 3, in the projection optical system described in claim 1, satisfy the following condition: 0.24<SAGΔR11 / f<0.53 (5) where SAGΔR11 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the fifth lens on the image display element side and the amount of sag at the effective maximum position when the aspherical surface of the fifth lens on the image display element side is treated as a paraxial spherical surface defined by the paraxial radius of curvature.

[0009] A head-mounted display according to a fourth aspect of the present invention is characterized by comprising the projection optical system according to any one of the first to third aspects of the present invention.

[0010] According to the present invention, it is possible to provide a projection optical system that is compact, has a wide angle of view, high resolution, and has lens performance that provides high image quality across the entire screen of the projected image, and a head-mounted display that uses this projection optical system.

[0011] FIG. 1 is a cross-sectional view taken along the optical axis showing the optical configuration of a projection optical system according to Example 1 of the present invention. FIG. 2 is a diagram showing (a) spherical aberration (SA), (b) curvature of field (FC), and (c) distortion (DT) when the projection optical system according to Example 1 is focused. FIG. 3 is a cross-sectional view taken along the optical axis showing the optical configuration of a projection optical system according to Example 2 of the present invention. FIG. 4 is a diagram showing (a) spherical aberration (SA), (b) curvature of field (FC), and (c) distortion (DT) when the projection optical system according to Example 2 is focused. FIG. 5 is a cross-sectional view taken along the optical axis showing the optical configuration of a projection optical system according to Example 3 of the present invention. FIG. 6 is a diagram showing (a) spherical aberration (SA), (b) curvature of field (FC), and (c) distortion (DT) when the projection optical system according to Example 3 is focused. FIG. 7 is a cross-sectional view taken along the optical axis showing the optical configuration of a projection optical system according to Example 4 of the present invention. 10A and 10B are diagrams showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 4 is focused; FIG. 10B is a cross-sectional view along the optical axis showing the optical configuration of the projection optical system according to Example 5 of the present invention; FIG. 10C is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 5 is focused; FIG. 10C is a cross-sectional view along the optical axis showing the optical configuration of the projection optical system according to Example 6 of the present invention; FIG. 10D is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 6 is focused; FIG. 10E is a cross-sectional view along the optical axis showing the optical configuration of the projection optical system according to Example 7 of the present invention; FIG. 10F is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 7 is focused; 10A and 10B are cross-sectional views along the optical axis showing the optical configuration of a projection optical system according to Example 8 of the present invention, and are diagrams showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion aberration (DT) when the projection optical system according to Example 8 is in focus.

[0012]

[0023] The following describes embodiments of the present invention with reference to the drawings. Fig. 1 is a cross-sectional view taken along the optical axis showing an example of the optical configuration of a projection optical system according to an embodiment of the present invention. The optical configuration in Fig. 1 corresponds to the optical configuration of the first example.

[0013] The projection optical system of the present invention comprises, in order from the projection surface side, which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and a concave aspherical surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element. Note that in all of the following examples, in the cross-sectional views of the optical configuration, S denotes the aperture stop, CG denotes a cover glass, and D denotes the display surface of the image display element located on the reduction side of the projection optical system.

[0014] In the projection optical system of the present invention, all surfaces of the first lens L1 to the fifth lens L5 are aspherical plastic lenses.

[0015] An image display element (not shown) that forms an image, such as an LCD, a digital mirror device (DMD), or a micro LED display, is disposed on the display surface D in the projection optical system of the present invention.

[0016] The projection optical system of the present invention also satisfies the following conditional expressions: 0.1<STP / TTL<0.18 (1) 0.47<Fb / f<0.69 (2) 1.75<f3 / f<2.31 (3) where, TTL is the total length of the projection optical system, STP is the distance between the aperture stop and the projection surface of the first lens, f is the focal length of the entire projection optical system, f3 is the focal length of the third lens, and Fb is the distance between the surface of the fifth lens facing the image display element and the image display element.

[0017] Conditional expression (1) is a conditional expression for making the overall length of the projection optical system short and compact, while ensuring the distance between the aperture stop and the projection surface of the first lens, and making it possible to place an eyepiece optical system such as a combiner or concave mirror at the position of the aperture stop.

[0018] Conditional expression (2) is a conditional expression for ensuring a distance between the image display element and the surface of the fifth lens facing the image display element, and for enabling the arrangement of optically functional elements such as various polarizing plates.

[0019] Furthermore, conditional expression (3) is a conditional expression for minimizing the maximum inclination angle (Chief ray angle (CRA)) of the chief ray of the light beam that emerges from the image display element and enters the projection optical system, while simultaneously achieving correction of distortion and curvature of field. If the value falls below the lower limit of conditional expression (3), the CRA in the intermediate image region, which is a position of 20% to 50% of the image height, becomes large and telecentricity deteriorates, resulting in an insufficient amount of light in the intermediate image region and worsening distortion and curvature of field, which are undesirable. If the value exceeds the upper limit of conditional expression (3), correction of curvature of field becomes insufficient, which is undesirable.

[0020] Furthermore, the projection optical system of this embodiment satisfies the following condition: 0.029<SAGΔR6 / f<0.15 (4) where SAGΔR6 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the third lens on the projection surface side and the amount of sag at the effective maximum position when the aspherical surface of the third lens on the projection surface side is a paraxial spherical surface defined by the paraxial radius of curvature.

[0021] If the lower limit of conditional expression (4) is not reached, the CRA at the 70% to 80% image height position becomes large, deteriorating telecentricity and resulting in a lack of light intensity in the peripheral region.If the upper limit of conditional expression (4) is reached, the CRA at the peripheral region becomes large compared to the 30% image height position, deteriorating telecentricity and resulting in a lack of light intensity in the peripheral region, which is also undesirable.

[0022] Furthermore, the projection optical system of this embodiment satisfies the following condition: 0.24<SAGΔR11 / f<0.53 (5) where SAGΔR11 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the fifth lens on the image display element side and the amount of sag at the effective maximum position when the aspherical surface of the fifth lens on the image display element side is treated as a paraxial spherical surface defined by the paraxial radius of curvature.

[0023] If the lower limit of conditional expression (5) is exceeded, the curvature of field will undesirably worsen, whereas if the upper limit of conditional expression (5) is exceeded, the CRA will increase and the telecentricity will deteriorate, resulting in a lack of light in the peripheral area and an undesirable worsening of the curvature of field.

[0024] The head-mounted display of the present invention has the above-described projection optical system. Preferably, the head-mounted display of the present invention includes two of the above-described projection optical systems, one for each of the observer's left and right eyes. The head-mounted display also includes a relay optical system disposed at the projection-side diaphragm of each projection optical system, and projects an image from an image display element via these projection optical systems, projecting the projected image as a virtual image onto the fundus of the observer.

[0025] The relay optical system is not particularly limited, and may be, for example, a combination of a light guide plate and a half mirror, or a combination of a concave mirror and a semi-transmitting surface.

[0026] Next, specific numerical examples of the projection optical system of the present invention will be shown. The symbols used in each example are as follows.

[0027] f: focal length of the entire projection optical system FNO: F-number FOV (2ω): projection angle of view r: paraxial radius of curvature d: lens thickness or air gap on the optical axis nd: refractive index of the lens material for the d-line νd: Abbe number of the lens material Fb: distance between the surface of the fifth lens facing the image display element and the image display element TTL: distance along the optical axis from the vertex of the first lens facing the projection surface to the surface of the fifth lens facing the image display element STP: distance between the aperture stop and the projection surface of the first lens SAGΔR6: difference between the amount of sag at the effective maximum position of the aspherical surface of the third lens facing the projection surface and the amount of sag at the effective maximum position when the aspherical surface of the third lens facing the projection surface is a paraxial spherical surface defined by the paraxial radius of curvature SAGΔR11: The difference between the amount of sag at the effective maximum position of the aspherical surface of the fifth lens on the image display element side and the amount of sag at the effective maximum position when the aspherical surface of the fifth lens on the image display element side is treated as a paraxial spherical surface defined by the paraxial radius of curvature. In addition, in each example, surfaces with an "*" written after the surface number are surfaces having an aspherical shape.

[0028] The aspherical shape is expressed by the following equation (1): z=(y) / ... ２ / r) / [1+{1-(1+K)(y / r) ２} １／２ ]+A4y ４ +A6y ６ +A8y ８ +A10y １０ ...(1) In the aspherical coefficients, E represents a power of 10, for example, 2.3×10 －２ is expressed as 2.3E-002. The symbols for these specification values ​​are also common to the numerical data in the examples described later. The symbols for these specification values ​​are also common to the numerical data in the examples described later.

[0029] Next, a description will be given of a projection optical system according to Example 1. Fig. 1 is a cross-sectional view taken along the optical axis and showing an example of the optical configuration of the projection optical system according to Example 1.

[0030] 2 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 1 is focused. For the spherical aberration (SA), field curvature (FC), and distortion (DT), the solid line (f) indicates the numerical value at a wavelength of 465 nm, the dashed line (d) indicates the numerical value at a wavelength of 525 nm, and the dashed line (c) indicates the numerical value at a wavelength of 617 nm. These conditions are the same in the examples described below.

[0031] Astigmatism is shown in the diagrams representing field curvature (FC), where S represents the sagittal image plane and T represents the tangential image plane. Furthermore, in the diagrams, FNO represents the F-number, and W represents the half angle of view. The symbols in the aberration diagrams are also used in the examples described below.

[0032] As shown in FIG. 1, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and an aspherical concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element.

[0033] The overall specifications of the projection optical system of Example 1 are as follows: f: 7.573 mm FNO: 2.049 FOV: 69.9° CRA: 2.1 f1: 7.484 mm f2: -7.138 mm f3: 17.406 mm f4: 10.071 mm f5: -24.535 mm TTL: 11.076 mm Fb: 4.674 mm

[0034] The surface data of the projection optical system of Example 1 is shown below (unit: mm).

[0035]

[0036] The aspherical data of the projection optical system of Example 1 is shown below. 2nd side K=-65.084005 A4= -1.7900640E-03, A6= -9.0790098E-05, A8= 1.8748970E-06, A10= 1.8407059E-08, A12= 3.1735669E-10, A14= -1.3054181E-09, A16= -4.2195861E-10 3rd side K= 0.000000 A4= -2.8681370E-04, A6= 1.6383127E-04, A8= -2.2776604E-07, A10= 1.7197448E-07, A12= 9.3089048E-09, A14= -2.1404257E-10, A16= -2.8615809E-11 4th side K= -1.761734 A4= 3.7698811E-03, A6= -8.6432682E-05, A8= 1.0678369E-06, A10= 5.6793759E-08, A12= 7.8209033E-10, A14= -2.6005760E-10 5th side K=-0.538716 A4=2.6670577E-03, A6= -6.1715970E-05, A8=8.1011682E-08, A10=1.9463652E-09, A12= -3.3007391E-11, A14=4.4869937E-13 6th side K=0.000000 A4=-3.2982702E-03, A6=1.9536159E-05, A8=2.4530132E-07, A10=1.2695524E-08, A12= 6.1291619E-10, A14=3.7292104E-11 7th side K=-1.076796 A4=-1.3631526E-03, A6=2.8581459E-05, A8=3.8215457E-07, A10=1.2446167E-08, A12= 4.1025180E-10, A14=1.6564885E-11 8th side K=0.000000 A4=-1.4022399E-03, A6=1.0210334E-05, A8=9.5249723E-08, A10=-4.9094043E-09, A12=-2.7153807E-10, A14=-1.2646357E-11 9th side K=0.000000 A4=1.2957258E-04, A6= 4.3180708E-05, A8=-5.6479700E-08, A10=-2.8820942E-09, A12=-1.1488204E-10, A14=-7.2767281E-12 10th page K=0.000000 A4=-6.5777101E-04, A6=4.9973921E-05, A8=-1.6372542E-06, A10=1.6843314E-08, A12=1.9325117E-10, A14=-9.4977662E-12 Page 11 K=0.000000 A4=-2.8585156E-03, A6=5.2801206E-05, A8=-1.5099954E-06, A10=-3.0672694E-09, A12=9.2688813E-11, A14=4.7539377E-12.

[0037] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 1 are as follows: (1) STP / TTL=0.15 (2) Fb / f=0.62 (3) f3 / f=2.30 (4) SAGΔR6 / f=0.148 (5) SAGΔR11 / f=0.36

[0038] Next, a description will be given of a projection optical system according to Example 2. Fig. 3 is a cross-sectional view taken along the optical axis and showing the optical configuration of the projection optical system according to Example 2.

[0039] FIG. 4 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 2 is in focus.

[0040] As shown in FIG. 3, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and an aspherical concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element.

[0041] The overall specifications of the projection optical system of Example 2 are as follows: f: 8.982 mm FNO: 2.050 FOV: 60.2° CRA: 2.0 f1: 7.798 mm f2: -7.148 mm f3: 18.141 mm f4: 10.850 mm f5: -21.714 mm TTL: 12.685 mm Fb: 5.226 mm

[0042] The surface data of the projection optical system of Example 2 is shown below (unit: mm).

[0043]

[0044] The aspherical data of the projection optical system of Example 2 is shown below. 2nd side K=-38.708209 A4=-1.0192751E-03, A6=-1.0316292E-04, A8=1.7879362E-07, A10=-2.5794356E-07, A12=4.9053011E-08, A14=-9.5121551E-10, A16=-1.1220606E-10 3rd side K=0.000000 A4=1.7264635E-04, A6=5.9409342E-05, A8=-6.2894705E-06, A10=2.3769254E-07, A12=1.3629564E-08, A14=5.3783918E-10, A16=-7.3317692E-11 4th side K=-1.818881 A4=3.5001328E-03, A6=-1.1524116E-04, A8=2.8327119E-06, A10=7.6967546E-08, A12=1.5201702E-09, A14=-2.6472317E-10 5th side K=-0.653921 A4=2.7562799E-03, A6=-5.7672870E-05, A8=3.5012301E-07, A10=-7.5438839E-10, A12=-2.6111953E-10, A14=4.7209072E-11 6th side K=0.000000 A4=-3.2491469E-03, A6=2.6924476E-05, A8=2.4774890E-07, A10=2.2334078E-08, A12=8.5185426E-10, A14=3.6775874E-11 7th side K=-1.516473 A4=-1.2648408E-03, A6=3.4448405E-05, A8=4.0567129E-07, A10=-3.7756829E-09, A12=2.9403336E-10, A14=1.4743196E-11 8th side K=0.000000 A4=-1.1464023E-03, A6=1.5587063E-05, A8=-1.2861470E-07, A10=-5.7069158E-09, A12=-2.5265968E-10, A14=-5.5202180E-12 9th side K=0.000000 A4=-2.10th page K=0.000000 A4=-9.1976206E-04, A6=4.8846715E-05, A8=-1.6214026E-06, A10=2.5526890E-08, A12=2.5006564E-10, A14=-5.3092132E-12 Page 11 K=0.000000 A4=-2.7993258E-03, A6=7.0414542E-05, A8=-1.4706036E-06, A10=-4.8200868E-09, A12=7.0416181E-11, A14=8.6905587E-12.

[0045] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 2 are as follows: (1) STP / TTL=0.13 (2) Fb / f=0.58 (3) f3 / f=2.02 (4) SAGΔR6 / f=0.098 (5) SAGΔR11 / f=0.25

[0046] Next, a description will be given of a projection optical system according to Example 3. Fig. 5 is a cross-sectional view taken along the optical axis and showing an example of the optical configuration of the projection optical system according to Example 3.

[0047] FIG. 6 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 3 is in focus.

[0048] As shown in FIG. 5, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and an aspherical concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element.

[0049] The overall specifications of the projection optical system of Example 3 are as follows: f: 7.521 mm FNO: 2.030 FOV: 70.0° CRA: 2.1 f1: 7.341 mm f2: -7.178 mm f3: 16.609 mm f4: 10.332 mm f5: -22.496 mm TTL: 11.500 mm Fb: 4.195 mm

[0050] The surface data of the projection optical system of Example 3 is shown below (unit: mm).

[0051]

[0052] The aspherical data of the projection optical system of Example 3 is shown below. 2nd side K=-66.891180 A4=-1.6947067E-03, A6=-9.3150974E-05, A8=1.5290743E-06, A10=2.4110153E-08, A12=-8.4541729E-09, A14=-2.7412620E-09, A16=-1.9876268E-10 3rd side K=0.000000 A4=-1.5331767E-04, A6=1.5283490E-04, A8=-9.6918983E-07, A10=1.9593737E-07, A12=9.3417275E-09, A14=3.7531984E-11, A16=-3.0810140E-11 4th side K=-1.753959 A4=3.7598127E-03, A6=-8.0905505E-05, A8=1.3450021E-06, A10=6.9706798E-08, A12=6.3062098E-10, A14=-3.2904971E-10 5th side K=-0.549504 A4=2.7062411E-03, A6=-6.0082792E-05, A8=8.3491518E-08, A10=1.2356010E-09, A12=-1.0148305E-10, A14=-7.3946266E-13 6th side K=0.000000 A4=-3.3852017E-03, A6=2.0354583E-05, A8=2.7953801E-07, A10=1.4804480E-08, A12=7.3820975E-10, A14=4.5259893E-11 7th side K=-1.159123 A4=-1.2915686E-03, A6=2.8930595E-05, A8=3.8954985E-07, A10=1.2910540E-08, A12=4.5658531E-10, A14=2.7488236E-11 8th side K=0.000000 A4=-1.3721651E-03, A6=1.4454110E-05, A8=1.5284026E-07, A10=-3.9023001E-09, A12=-2.5618995E-10, A14=-1.1791484E-11 9th side K=0.000000 A4=1.1953538E-05, A6=4.4324274E-05, A8=6.0777066E-08, A10=-1.7837385E-10, A12=-1.2582683E-10, A14=-9.1515784E-12 10th side K=0.000000 A4=-6.6446521E-04, A6=4.7575345E-05, A8=-1.6863761E-06, A10=1.8229372E-08, A12=2.6948171E-10, A14=-4.4010640E-12 Page 11 K=0.000000 A4=-2.9465719E-03, A6=5.2747182E-05, A8=-1.4683289E-06, A10=-2.8333639E-09, A12=1.5378522E-10, A14=7.9288304E-12.

[0053] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 3 are as follows: (1) STP / TTL=0.15 (2) Fb / f=0.56 (3) f3 / f=2.21 (4) SAGΔR6 / f=0.140 (5) SAGΔR11 / f=0.32

[0054] Next, a description will be given of a projection optical system according to Example 4. Fig. 7 is a cross-sectional view taken along the optical axis showing the optical configuration of the projection optical system according to Example 4.

[0055] FIG. 8 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 4 is in focus.

[0056] As shown in FIG. 7, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and an aspherical concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element.

[0057] The overall specifications of the projection optical system of Example 4 are as follows: f: 7.440 mm FNO: 2.011 FOV: 69.7° CRA: 2.1 f1: 7.473 mm f2: -7.123 mm f3: 16.987 mm f4: 10.019 mm f5: -25.336 mm TTL: 11.158 mm Fb: 4.675 mm

[0058] The surface data of the projection optical system of Example 4 is shown below (unit: mm).

[0059]

[0060] The aspherical data of the projection optical system of Example 4 is shown below. 2nd side K=-66.236893 A4=-1.8011294E-03, A6=-9.0416839E-05, A8=2.2493584E-06, A10=6.8268886E-08, A12=6.0295989E-09, A14=-3.3621218E-10, A16=-8.8901663E-11 3rd side K=0.000000 A4=-1.5815379E-04, A6=1.6678273E-04, A8=-4.0377030E-07, A10=1.6882798E-07, A12=1.2045767E-08, A14=2.6252434E-10, A16=1.7404235E-11 4th side K=-1.759392 A4=3.7540136E-03, A6=-8.6650580E-05, A8=1.0852789E-06, A10=5.5871098E-08, A12=6.5355975E-10, A14=-2.5601787E-10 5th side K=-0.536950 A4=2.6612529E-03, A6=-6.1657793E-05, A8=6.9614210E-08, A10=1.3580170E-09, A12=-4.9948619E-11, A14=1.4438523E-13 6th side K=0.000000 A4=-3.2868717E-03, A6=1.9246330E-05, A8=2.6442529E-07, A10=1.4374725E-08, A12=7.0544675E-10, A14=4.2674252E-11 7th page K=-1.050586 A4=-1.3781184E-03, A6=2.8690460E-05, A8=3.7422873E-07, A10=1.2103259E-08, A12=4.1441259E-10, A14=1.7973831E-11 8th side K=0.000000 A4=-1.3823894E-03, A6=9.9076134E-06, A8=9.2049803E-08, A10=-4.8267973E-09, A12=-2.6418654E-10, A14=-1.2273412E-11 9th side K=0.000000 A4=1.1672289E-04, A6=4.3104384E-05, A8=-6.0442530E-08, A10=-3.0184460E-09, A12=-1.2012990E-10, A14=-7.5198315E-12 10th side K=0.000000 A4=-6.2533958E-04, A6=5.0104007E-05, A8=-1.6392942E-06, A10=1.6704284E-08, A12=1.8838361E-10, A14=-9.6472522E-12 Page 11 K=0.000000 A4=-2.9001198E-03, A6=5.2957338E-05, A8=-1.4906070E-06, A10=-2.3580753E-09, A12=1.1361364E-10, A14=5.2963094E-12.

[0061] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 4 are as follows: (1) STP / TTL=0.11 (2) Fb / f=0.63 (3) f3 / f=2.28 (4) SAGΔR6 / f=0.141 (5) SAGΔR11 / f=0.34

[0062] Next, a description will be given of a projection optical system according to Example 5. Fig. 9 is a cross-sectional view taken along the optical axis showing the optical configuration of the projection optical system according to Example 5.

[0063] FIG. 10 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 5 is in focus.

[0064] As shown in FIG. 9, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave shape on the projection surface side, a third lens having positive refractive power and a concave aspherical shape on the projection surface side, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface on the image display element side.

[0065] The overall specifications of the projection optical system of Example 5 are as follows: f: 7.405 mm FNO: 2.001 FOV: 69.9° CRA: 2.6 f1: 7.411 mm f2: -7.354 mm f3: 16.581 mm f4: 10.286 mm f5: -19.956 mm TTL: 12.152 mm Fb: 3.520 mm

[0066] The surface data of the projection optical system of Example 5 is shown below (unit: mm).

[0067]

[0068] The aspherical data of the projection optical system of Example 5 is shown below. 2nd side K=-65.080663 A4=-1.6105002E-03, A6=-1.0071651E-04, A8=1.5548617E-06, A10=1.0270460E-07, A12=-8.7147349E-09, A14=-3.8656299E-09, A16=-1.9363704E-10 3rd side K=0.000000 A4=-9.8289912E-05, A6=1.4756724E-04, A8=-9.0001604E-07, A10=2.2147671E-07, A12=1.2372291E-08, A14=-4.9836265E-11, A16=-8.6791456E-11 4th side K=-1.747426 A4=3.7811784E-03, A6=-8.0224766E-05, A8=1.4828517E-06, A10=7.0090541E-08, A12=6.4668409E-10, A14=-3.3647016E-10 5th side K=-0.549791 A4=2.6945960E-03, A6=-5.9476663E-05, A8=1.3860437E-07, A10=2.1558901E-09, A12=-8.6519637E-11, A14=1.1759209E-12 6th side K=0.000000 A4=-3.2801157E-03, A6=2.0925941E-05, A8=2.8020543E-07, A10=1.4675268E-08, A12=7.6096711E-10, A14=4.4092982E-11 7th side K=-1.108360 A4=-1.3210922E-03, A6=2.9261789E-05, A8=4.1009420E-07, A10=1.3739527E-08, A12=4.9398326E-10, A14=2.4195970E-11 8th side K=0.000000 A4=-1.3000539E-03, A6=1.2647199E-05, A8=1.0052811E-07, A10=-3.3435977E-09, A12=-2.2789733E-10, A14=-1.1183824E-11 9th side K=0.000000 A4=-5.2736442E-05, A6=4.4198160E-05, A8=1.2994812E-07, A10=1.5136524E-09, A12=-1.1140077E-10, A14=-8.3623423E-12 10th side K=0.000000 A4=-6.5162089E-04, A6=4.8645859E-05, A8=-1.6385287E-06, A10=1.9924127E-08, A12=3.4009222E-10, A14=-5.1190833E-12 Page 11 K=0.000000 A4=-2.9680964E-03, A6=4.9104797E-05, A8=-1.5351789E-06, A10=-3.8301401E-09, A12=2.6060763E-10, A14=1.5260078E-11.

[0069] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 5 are as follows: (1) STP / TTL=0.14 (2) Fb / f=0.48 (3) f3 / f=2.24 (4) SAGΔR6 / f=0.135 (5) SAGΔR11 / f=0.28

[0070] Next, a description will be given of a projection optical system according to Example 6. Fig. 11 is a cross-sectional view taken along the optical axis showing the optical configuration of the projection optical system according to Example 6.

[0071] FIG. 12 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 6 is in focus.

[0072] As shown in FIG. 11, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave surface facing the projection surface, a third lens having positive refractive power and an aspherical concave surface facing the projection surface, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface facing the image display element.

[0073] The overall specifications of the projection optical system of Example 6 are as follows: f: 7.564 mm FNO: 2.403 FOV: 69.9° CRA: 2.1 f1: 7.484 mm f2: -7.144 mm f3: 17.405 mm f4: 10.069 mm f5: -24.544 mm TTL: 11.070 mm Fb: 4.671 mm

[0074] The surface data of the projection optical system of Example 6 is shown below (unit: mm).

[0075]

[0076] The aspherical data of the projection optical system of Example 6 is shown below. 2nd side K=-64.695710 A4=-1.7868465E-03, A6=-9.0777509E-05, A8=1.8255186E-06, A10=1.0011614E-08, A12=-7.2492603E-10, A14=-1.4398650E-09, A16=-4.3971086E-10 3rd side K=0.000000 A4=-2.8632854E-04, A6=1.6393081E-04, A8=-2.1715285E-07, A10=1.7272528E-07, A12=9.3488628E-09, A14=-2.1206268E-10, A16=-2.8435302E-11 4th side K=-1.761561 A4=3.7694540E-03, A6=-8.6437024E-05, A8=1.0690387E-06, A10=5.6932960E-08, A12=7.9233562E-10, A14=-2.5951596E-10 5th side K=-0.538794 A4=2.6673296E-03, A6=-6.1703855E-05, A8=8.1280078E-08, A10=1.9436494E-09, A12=-3.3685980E-11, A14=4.0211181E-13 6th side K=0.000000 A4=-3.2984110E-03, A6=1.9531204E-05, A8=2.4562392E-07, A10=1.2739388E-08, A12=6.1625840E-10, A14=3.7503548E-11 7th side K=-1.077274 A4=-1.3629005E-03, A6=2.8593665E-05, A8=3.8230518E-07, A10=1.2433536E-08, A12=4.0896059E-10, A14=1.6486778E-11 8th side K=0.000000 A4=-1.4018406E-03, A6=1.0216042E-05, A8=9.5363556E-08, A10=-4.9085107E-09, A12=-2.7153975E-10, A14=-1.2644969E-11 9th side K=0.000000 A4=1.2939585E-04, A6=4.3180700E-05, A8=-5.6444615E-08, A10=-2.8803615E-09, A12=-1.1487753E-10, A14=-7.2811628E-12 10th side K=0.000000 A4=-6.5777707E-04, A6=4.9969388E-05, A8=-1.6374147E-06, A10=1.6836889E-08, A12=1.9303034E-10, A14=-9.5041630E-12 Page 11 K=0.000000 A4=-2.8583685E-03, A6=5.2807554E-05, A8=-1.5097925E-06, A10=-3.0607330E-09, A12=9.2868723E-11, A14=4.7573761E-12.

[0077] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 6 are as follows: (1) STP / TTL=0.15 (2) Fb / f=0.62 (3) f3 / f=2.30 (4) SAGΔR6 / f=0.147 (5) SAGΔR11 / f=0.36

[0078] Next, a description will be given of a projection optical system according to Example 7. Fig. 13 is a cross-sectional view taken along the optical axis showing the optical configuration of the projection optical system according to Example 7.

[0079] FIG. 14 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 7 is in focus.

[0080] As shown in FIG. 13, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave shape on the projection surface side, a third lens having positive refractive power and a concave aspherical shape on the projection surface side, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface on the image display element side.

[0081] The overall specifications of the projection optical system of Example 7 are as follows: f: 6.283 mm FNO: 2.402 FOV: 79.9° CRA: 2.0 f1: 5.465 mm f2: -5.749 mm f3: 11.209 mm f4: 9.741 mm f5: -13.650 mm TTL: 10.222 mm Fb: 3.838 mm

[0082] The surface data of the projection optical system of Example 7 is shown below (unit: mm).

[0083]

[0084] The aspherical data of the projection optical system of Example 7 is shown below. 2nd side K=-9.534913 A4=-1.8814934E-03, A6=-2.7478912E-04, A8=-1.9063384E-05, A10=-8.1029832E-07, A12=2.6384066E-08, A14=1.1358477E-08, A16=-2.8827229E-09 3rd side K=0.000000 A4=3.8334612E-03, A6=8.2294140E-05, A8=-7.3026932E-06, A10=6.7851079E-07, A12=2.6374044E-08, A14=1.4110934E-09, A16=8.1266767E-10 4th side K=-1.593577 A4=3.9598117E-03, A6=-3.3795339E-05, A8=4.3965780E-06, A10=2.5028390E-07, A12=-2.5517098E-09, A14=-1.2297679E-09 5th side K=-0.618527 A4=2.9586381E-03, A6=-5.5261994E-05, A8=-1.2780136E-07, A10=-2.6998687E-08, A12=-1.8259772E-09, A14=8.7173157E-11 6th side K=0.000000 A4=-2.6900984E-03, A6=3.2427566E-05, A8=-4.2211779E-08, A10=2.9299557E-08, A12=1.6157223E-09, A14=7.5826159E-11 7th side K=-1.007578 A4=-1.3546811E-03, A6=1.4995229E-05, A8=5.7646133E-07, A10=2.1669975E-08, A12=3.9144543E-10, A14=6.3257135E-11 8th side K=0.000000 A4=-2.0614305E-03, A6=1.4164665E-05, A8=7.0017240E-08, A10=8.7681150E-09, A12=9.4003707E-11, A14=-3.3144174E-11 9th side K=0.000000 A4=-5.6935727E-04, A6=5.7522820E-05, A8=3.4307652E-07, A10=3.5444567E-09, A12=5.0372924E-11, A14=6.3348390E-12 10th page K=0.000000 A4=-7.1257472E-06, A6=4.8442536E-05, A8=-1.5124877E-06, A10=2.2018611E-08, A12=2.4650058E-10, A14=-8.5556275E-12 Page 11 K=0.000000 A4=-3.3430211E-03, A6=6.3995948E-05, A8=-2.6280980E-06, A10=3.0866353E-08, A12=2.1014789E-10, A14=-1.7695668E-11.

[0085] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 7 are as follows: (1) STP / TTL=0.17 (2) Fb / f=0.61 (3) f3 / f=1.78 (4) SAGΔR6 / f=0.054 (5) SAGΔR11 / f=0.53

[0086] Next, a description will be given of a projection optical system according to Example 8. Fig. 15 is a cross-sectional view taken along the optical axis showing the optical configuration of the projection optical system according to Example 8.

[0087] FIG. 16 is a diagram showing (a) spherical aberration (SA), (b) field curvature (FC), and (c) distortion (DT) when the projection optical system according to Example 8 is in focus.

[0088] As shown in FIG. 15, this projection optical system is composed of, in order from the projection surface side which is the enlarged projection surface, an aperture stop, a first lens having positive refractive power, a second lens having negative refractive power and a concave shape on the projection surface side, a third lens having positive refractive power and a concave aspherical shape on the projection surface side, a fourth lens having positive refractive power, and a fifth lens having negative refractive power and an aspherical surface on the image display element side.

[0089] The overall specifications of the projection optical system of Example 8 are as follows: f: 6.330 mm FNO: 2.401 FOV: 80.1° CRA: 1.9 f1: 5.500 mm f2: -5.760 mm f3: 11.101 mm f4: 9.720 mm f5: -13.858 mm TTL: 9.892 mm Fb: 4.316 mm

[0090] The surface data of the projection optical system of Example 8 is shown below (unit: mm).

[0091]

[0092] The aspherical data of the projection optical system of Example 8 is shown below. 2nd side K=-12.688964 A4=-2.0039362E-03, A6=-2.8355793E-04, A8=-2.4077540E-05, A10=-1.2237179E-06, A12=7.8001701E-09, A14=1.0323553E-08, A16=-3.0350793E-09 3rd side K=0.000000 A4=3.8432993E-03, A6=6.2261719E-05, A8=-8.0109078E-06, A10=6.5080168E-07, A12=2.3947389E-08, A14=1.1703878E-09, A16=7.8679312E-10 4th side K=-1.591230 A4=3.9790417E-03, A6=-3.1164391E-05, A8=4.5199890E-06, A10=2.5402012E-07, A12=-2.1322139E-09, A14=-1.3003934E-09 5th side K=-0.615197 A4=2.9542610E-03, A6=-5.6395285E-05, A8=-1.8682623E-07, A10=-2.9132324E-08, A12=-1.9000826E-09, A14=8.5594317E-11 6th side K=0.000000 A4=-2.6952050E-03, A6=3.2692055E-05, A8=-5.1823290E-08, A10=2.7911394E-08, A12=1.5299350E-09, A14=7.0493366E-11 7th side K=-1.012527 A4=-1.3394662E-03, A6=1.4476388E-05, A8=5.6218135E-07, A10=2.2118527E-08, A12=4.6007503E-10, A14=6.7658631E-11 8th side K=0.000000 A4=-2.0998140E-03, A6=1.3747604E-05, A8=9.4663340E-08, A10=9.1248066E-09, A12=1.0349467E-10, A14=-3.2921875E-11 9th side K=0.000000 A4=-5.4800656E-04, A6=5.7883565E-05, A8=3.4253202E-07, A10=3.3134870E-09, A12=4.3539924E-11, A14=6.5055288E-12 10th page K=0.000000 A4=-1.7456387E-05, A6=4.8237547E-05, A8=-1.5134550E-06, A10=2.2189089E-08, A12=2.5884316E-10, A14=-7.9420900E-12 Page 11 K=0.000000 A4=-3.3460974E-03, A6=6.4168962E-05, A8=-2.6234538E-06, A10=3.0884069E-08, A12=2.0415573E-10, A14=-1.8130493E-11.

[0093] The values ​​corresponding to the conditional expressions (1) to (5) of the projection optical system of Example 8 are as follows: (1) STP / TTL=0.17 (2) Fb / f=0.68 (3) f3 / f=1.75 (4) SAGΔR6 / f=0.030 (5) SAGΔR11 / f=0.42

[0094] L1 First lens L2 Second lens L3 Third lens L4 Fourth lens L5 Fifth lens CG Cover glass D Display surface of image display element S Aperture diaphragm

Claims

1. A projection optical system that projects an image from an image display element onto a projection surface, comprising, in order from the projection surface side, an aperture stop, a first lens with positive refractive power, a second lens with negative refractive power and a concave surface on the projection surface side, a third lens with positive refractive power and an aspherical concave surface on the projection surface side, a fourth lens with positive refractive power, and a fifth lens with negative refractive power and an aspherical surface on the image display element side, and having a projection angle of view (FOV) of 60° or more, and satisfying the following conditional expression: 0.1<STP / TTL<0.18 (1) 0.47<Fb / f<0.69 (2) 1.75<f3 / f<2.31 (3) Here, TTL is the total length of the projection optical system, STP is the distance between the aperture stop and the projection surface of the first lens, f is the focal length of the entire projection optical system, f3 is the focal length of the third lens, and Fb is the distance between the surface of the fifth lens facing the image display element and the image display element.

2. The projection optical system according to claim 1, characterized in that the following condition is satisfied: 0.029<SAGΔR6 / f<0.15 (4) where SAGΔR6 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the third lens on the projection surface side and the amount of sag at the effective maximum position when the aspherical surface of the third lens on the projection surface side is a paraxial spherical surface defined by the paraxial radius of curvature.

3. The projection optical system according to claim 1, wherein the following condition is satisfied: 0.24<SAGΔR11 / f<0.53 (5) where SAGΔR11 is the difference between the amount of sag at the effective maximum position of the aspherical surface of the fifth lens on the image display element side and the amount of sag at the effective maximum position when the aspherical surface of the fifth lens on the image display element side is treated as a paraxial spherical surface defined by the paraxial radius of curvature.

4. A head-mounted display having a projection optical system according to any one of claims 1 to 3.

Images