Projection optical system and projection type display device

Abstract

The invention provides an optical system for projection and a projection-type display device provided with the same, wherein the optical system for projection has a wide viewing angle and a long back focal length, can be miniaturized, and can maintain good optical performance. This projection optical system projects an image on a reduction-side imaging surface onto an enlargement-side imaging surface, the enlargement-side half angle of view being 50 degrees or more, and when one lens component is set as one single lens or one cemented lens, the image on the reduction-side imaging surface is not less than the magnification-side half angle of view, and the magnification-side half angle of view is not less than the magnification-side half angle of view. The projection optical system includes a P lens component, which is a lens component closest to the magnification side and having a positive refractive power, among lens components included in the projection optical system, and an N lens component, which is a lens component disposed adjacent to the magnification side of the P lens component and having a negative refractive power, and satisfies a preset conditional expression.

Description

Technical Field

[0001] The technology of the present invention relates to a projection optical system and a projection display device. Background Art

[0002] As optical systems applicable to projection-type display devices, optical systems described in Japanese Patent Documents 1 and 2 listed below are known.

[0003] Patent Document 1: International Publication No. 2017 / 195857

[0004] Patent Document 2: International Publication No. 2020 / 110380

[0005] There is a growing demand for projection optical systems that have a wide viewing angle, a long back focus, are compact, and maintain excellent optical performance. Summary of the Invention

[0006] The present invention has been made in view of the above circumstances, and provides a projection optical system having a wide viewing angle and a long back focus, which is compact and maintains good optical performance, and a projection display device including the projection optical system.

[0007] A first aspect of the present invention is a projection optical system that projects an image on a reduction-side imaging surface onto an enlargement-side imaging surface, wherein a half angle of view on the enlargement side is 50 degrees or greater. When one lens component is a single lens or a cemented lens, the projection optical system includes: a P lens component having positive refractive power, which is a lens component closest to the enlargement side, among the lens components included in the projection optical system; and an N lens component having negative refractive power, which is a lens component disposed adjacent to the enlargement side of the P lens component.

[0008] The projection optical system satisfies the following conditional equations (1), (2), (3), (4), and (5):

[0009] 1<Zp / Ymax<4 (1)

[0010] 0.2<Rpf / Ymax<2.3 (2)

[0011] 0.2<Rnr / Ymax<5 (3)2<Bf / Ymax<8 (4)

[0012] 1.35<Y50 / Y40<1.5 (5).

[0013] Here, the maximum image height on the image plane on the reduction side is set as Ymax. The distance on the optical axis from the surface of the optical element with optical power closest to the magnification side of the projection optical system to the lens surface of the P lens component closest to the magnification side is set as Zp. The radius of curvature of the lens surface closest to the magnification side of the P lens component is set as Rpf. The radius of curvature of the lens surface closest to the magnification side of the N lens component is set as Rnr. The back focal length on the reduction side of the air-converted distance of the projection optical system is set as Bf. The image height on the image plane on the reduction side of a ray with a half-angle of view of 40 degrees on the magnification side is set as Y40. The image height on the image plane on the reduction side of a ray with a half-angle of view of 50 degrees on the magnification side is set as Y50. If the projection optical system is a variable magnification optical system, Ymax, Zp, Bf, Y40, and Y50 are set to the values at the wide-angle end.

[0014] The second mode of the present invention is a projection optical system of the first mode, which includes a first optical system and a second optical system in sequence along the optical path from the magnification side to the reduction side, the second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction side imaging surface, and the first optical system re-images the intermediate image onto the magnification side imaging surface.

[0015] In a third aspect of the present invention, in the projection optical system of the first aspect, when the interval between the N lens component and the P lens component on the optical axis is set to Dnp, and when the projection optical system is a variable magnification optical system, Dnp is set to a value at the wide-angle end,

[0016] The projection optical system satisfies the conditional formula (6) represented by the following formula:

[0017] 0<Dnp / Ymax<0.1 (6).

[0018] A fourth aspect of the present invention is a projection optical system according to the first aspect, wherein, when the curvature radius of the lens surface closest to the reduction side of the P lens component is denoted as Rpr,

[0019] The projection optical system satisfies the conditional equation (7) represented by the following equation:

[0020] 0<(Rpr+Rpf) / (Rpr-Rpf)<2 (7).

[0021] In a fifth aspect of the present invention, in the projection optical system of the first aspect, when the larger of the maximum effective diameter of the lens surface of the P lens component closest to the magnification side and the maximum effective diameter of the lens surface of the P lens component closest to the reduction side is defined as EDp,

[0022] The projection optical system satisfies the conditional formula (8) represented by the following formula:

[0023] 0.5<EDp / Ymax<2.5 (8).

[0024] According to a sixth aspect of the present invention, in the projection optical system according to the first aspect, when the curvature radius of the lens surface closest to the magnification side of the N lens component is denoted as Rnf,

[0025] The projection optical system satisfies the conditional formula (9) represented by the following formula:

[0026] -1<(Rnr+Rnf) / (Rnr-Rnf)<0.5 (9).

[0027] According to a seventh aspect of the present invention, in the projection optical system of the second aspect, the projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0028] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0029] 0.2<dAmax / Ymax<2.5 (10).

[0030] Here, the group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the projection optical system is referred to as the magnification-side fixed group. The longest air gap between lens surfaces on the optical axis within the magnification-side fixed group is referred to as dAmax. If the projection optical system is a variable magnification optical system, dAmax is set to the value at the wide-angle end.

[0031] According to an eighth aspect of the present invention, in the projection optical system of the second aspect, the projection optical system is a zoom lens, and the second optical system includes, in order from the magnification side to the reduction side, a lens group 2A, a lens group 2B, a lens group 2C, and a lens group 2D along the optical path. During zooming, the lens groups 2A and 2D are fixed relative to the image plane on the reduction side, while the lens groups 2B and 2C move with their spacings changing. In this case, in the second optical system, the group whose spacing in the optical axis direction with respect to adjacent groups changes during zooming is defined as a single lens group.

[0032] According to a ninth aspect of the present invention, in the projection optical system of the eighth aspect, when the focal length of the 2B lens group is set to f2B and the focal length of the 2C lens group is set to f2C,

[0033] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0034] 0<f2B / |f2C|<0.5 (11).

[0035] According to a tenth aspect of the present invention, in the projection optical system of the first aspect, when the larger of the maximum effective diameter of the magnification-side surface of the lens closest to the magnification side of the projection optical system and the maximum effective diameter of the reduction-side surface of the lens closest to the magnification side of the projection optical system is set to EDL1, and the specific gravity of the lens closest to the magnification side of the projection optical system is set to ρL1,

[0036] The projection optical system satisfies the conditional formula (12) represented by the following formula:

[0037] 0.5<EDL1×ρL1 / Ymax<10 (12).

[0038] According to an eleventh aspect of the present invention, in the projection optical system of the first aspect, the P lens component is a single lens, and the refractive index of the P lens component with respect to d-line is 1.65 or more.

[0039] According to a twelfth aspect of the present invention, in the projection optical system of the eleventh aspect, the N lens component is a single lens, and the refractive index of the N lens component with respect to d-line is 1.65 or less.

[0040] According to a thirteenth aspect of the present invention, in the projection optical system according to the second aspect, the first optical system includes an aspherical lens.

[0041] A fourteenth aspect of the present invention is the projection optical system according to the thirteenth aspect, wherein the first optical system includes two aspherical lenses.

[0042] According to the 15th embodiment of the present invention, in the projection optical system of the 13th embodiment, the lens surface of the first optical system closest to the magnification side is an aspheric surface, and the aspheric surface is concave toward the magnification side in the paraxial region, and has an inflection point in which the concave and convex shape changes midway as it moves from the optical axis to the peripheral portion.

[0043] According to a sixteenth aspect of the present invention, in the projection optical system of the second aspect, the reduction side is telecentric.

[0044] A seventeenth aspect of the present invention is a projection display device including the projection optical system according to any one of the first to sixteenth aspects.

[0045] The 18th embodiment of the present invention is a projection optical system, which includes a first optical system and a second optical system in sequence along the optical path from the magnification side to the reduction side, wherein the second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction side imaging surface, and the first optical system re-images the intermediate image on the magnification side imaging surface. A focusing group is arranged on the closest magnification side of the projection optical system, and the focusing group includes more than 6 lenses and adjusts the focus of the entire image surface when the projection distance changes by moving along the optical axis. When the focus is adjusted, the intervals between all lenses in the focusing group remain unchanged.

[0046] According to a nineteenth aspect of the present invention, in the projection optical system of the eighteenth aspect, the focusing group is arranged in the first optical system.

[0047] According to a 20th aspect of the present invention, in the projection optical system according to the 18th aspect,

[0048] The projection optical system satisfies the conditional formula (13) represented by the following formula:

[0049] 0.02<(1-βF 2 )×βFr 2 <0.2 (13).

[0050] Here, the paraxial lateral magnification of the focus group is βF. The combined paraxial lateral magnification of all lenses closer to the reduction side than the focus group is βFr. When the projection optical system is a variable magnification optical system, βF and βFr are set to the values at the wide-angle end.

[0051] According to a 21st aspect of the present invention, in the projection optical system according to the 18th aspect,

[0052] The projection optical system satisfies the conditional equation (14) represented by the following equation:

[0053] 0.1<((1-βF 2 )×βFr 2 ) / ΔtF<0.5 (14).

[0054] Here, the paraxial lateral magnification of the focusing group is βF. The combined paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFr. The maximum image height on the reduction-side image plane is Ymax. The change in the tangential image plane along the optical axis at a half angle of view of 50 degrees when the focusing group moves 0.1×Ymax along the optical axis is ΔtF. If the projection optical system is a variable magnification optical system, βF, βFr, Ymax, and ΔtF are set to the values at the wide-angle end.

[0055] According to a 22nd aspect of the present invention, in the projection optical system according to the 18th aspect, the focusing group includes two or more positive lenses.

[0056] According to the 23rd mode of the present invention, in the projection optical system of the 18th mode, the lens surface of the focusing group closest to the magnification side is an aspheric surface, and the aspheric surface is concave toward the magnification side in the paraxial region, and has an inflection point in which the concave and convex shape changes midway as it moves from the optical axis toward the peripheral portion.

[0057] According to a 24th aspect of the present invention, in the projection optical system according to the 18th aspect, one of the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is a positive lens, and the other is a negative lens.

[0058] The projection optical system satisfies the conditional formula (15) represented by the following formula:

[0059] 0≤dFr12 / Ymax<0.1 (15).

[0060] Here, the distance on the optical axis between the first lens from the reduction side of the focus group and the second lens from the reduction side is denoted by dFr1 / 2. The maximum image height on the image plane on the reduction side is denoted by Ymax. If the projection optical system is a variable magnification optical system, Ymax is set to the value at the wide-angle end.

[0061] According to a 25th aspect of the present invention, in the projection optical system according to the 18th aspect, a back focus correction group is provided for adjusting the back focus by moving along the optical axis.

[0062] According to a 26th aspect of the present invention, in the projection optical system according to the 18th aspect, the projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0063] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0064] 0.2<dAmax / Ymax<2.5 (10).

[0065] Here, the group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the projection optical system is referred to as the magnification-side fixed group. The longest air gap between lens surfaces on the optical axis within the magnification-side fixed group is referred to as dAmax. If the projection optical system is a variable magnification optical system, dAmax is set to the value at the wide-angle end.

[0066] According to a twenty-seventh aspect of the present invention, in the projection optical system of the eighteenth aspect, the projection optical system is a zoom lens, and the second optical system includes, in order from the magnification side to the reduction side, a lens group 2A, a lens group 2B, a lens group 2C, and a lens group 2D along the optical path. During zooming, the lens group 2A and the lens group 2D are fixed relative to the image plane on the reduction side, while the lens group 2B and the lens group 2C move with their spacing changed. In this case, in the second optical system, the group whose spacing in the optical axis direction with respect to an adjacent group changes during zooming is defined as a single lens group.

[0067] According to a 28th aspect of the present invention, in the projection optical system according to the 27th aspect, when the focal length of the 2B lens group is set to f2B and the focal length of the 2C lens group is set to f2C,

[0068] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0069] 0<f2B / |f2C|<0.5 (11).

[0070] A 29th aspect of the present invention is a projection display device including the projection optical system according to any one of the 18th to 28th aspects.

[0071] A 30th aspect of the present invention is a projection optical system comprising a first optical system and a second optical system, wherein the second optical system forms an intermediate image between the first and second optical systems and at a position conjugate with a reduction-side imaging plane, and the first optical system re-images the intermediate image onto the magnification-side imaging plane. A focusing group and a back focus correction group are arranged within the projection optical system, wherein the focusing group adjusts the focus of the entire image plane when the projection distance changes by moving along the optical axis, and the back focus correction group adjusts the back focus by moving along the optical axis.

[0072] The projection optical system satisfies the conditional equation (16) represented by the following equation:

[0073] 5<ZFBr / |f|<20 (16).

[0074] Here, the distance on the optical axis from the lens surface closest to the magnification side of the first optical system to the lens surface closest to the reduction side among the lens surfaces included in the focusing group and the back focus correction group is denoted as ZFBr. The focal length of the projection optical system is denoted as f. If the projection optical system is a variable magnification optical system, ZFBr and f are set to the values at the wide-angle end.

[0075] According to a 31st aspect of the present invention, in the projection optical system according to the 30th aspect,

[0076] The projection optical system satisfies the following conditional equations (17) and (18):

[0077] 0.02<(1-βFF 2 )×βFFr 2 <0.2(17)

[0078] 0.1<|(1-βB 2 )×βBr 2 |<2 (18).

[0079] Here, the paraxial lateral magnification of the focusing group is βFF. The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr. The paraxial lateral magnification of the back focus correction group is βB. The composite paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr. If the projection optical system is a variable magnification optical system, βFF, βFFr, βB, and βBr are set to the values at the wide-angle end.

[0080] According to a 32nd aspect of the present invention, in the projection optical system according to the 30th aspect,

[0081] The projection optical system satisfies the conditional formula (19) represented by the following formula:

[0082] 0.7<|(1-βB 2 )×βBr 2 | / ΔtB<1.4 (19).

[0083] Here, the paraxial lateral magnification of the back focus correction group is βB. The combined paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr. The maximum image height on the reduction-side image plane is Ymax. The change in the tangential image plane along the optical axis at a half angle of view of 50 degrees when the back focus correction group is moved 0.1×Ymax along the optical axis is ΔtB. If the projection optical system is a variable magnification optical system, βB, βBr, Ymax, and ΔtB are set to the values at the wide-angle end.

[0084] According to a 33rd aspect of the present invention, in the projection optical system according to the 30th aspect,

[0085] The projection optical system satisfies the conditional equation (20) represented by the following equation:

[0086] 0.1<((1-βFF 2 )×βFFr 2 ) / ΔtFF<0.5 (20).

[0087] Here, the paraxial lateral magnification of the focusing group is βFF. The combined paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr. The maximum image height on the reduction-side imaging plane is Ymax. The change in the tangential image plane along the optical axis at a half-angle of view of 50 degrees when the focusing group moves 0.1×Ymax along the optical axis is ΔtFF. If the projection optical system is a variable magnification optical system, ββFF, βFFr, Ymax, and ΔtFF are set to the values at the wide-angle end.

[0088] According to a 34th aspect of the present invention, in the projection optical system of the 30th aspect, the focusing group and the back focus correction group can move independently of each other.

[0089] According to a 35th aspect of the present invention, in the projection optical system of the 30th aspect, the projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0090] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0091] 0.2<dAmax / Ymax<2.5 (10).

[0092] Here, the group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the projection optical system is referred to as the magnification-side fixed group. The longest air gap between lens surfaces on the optical axis within the magnification-side fixed group is referred to as dAmax. If the projection optical system is a variable magnification optical system, dAmax is set to the value at the wide-angle end.

[0093] According to a 36th aspect of the present invention, in the projection optical system of the 30th aspect, the projection optical system is a zoom lens, and the second optical system includes, in order from the magnification side to the reduction side, a lens group 2A, a lens group 2B, a lens group 2C, and a lens group 2D along the optical path. During zooming, the lens groups 2A and 2D are fixed relative to the image plane on the reduction side, while the lens groups 2B and 2C move with their spacings changing. In this case, in the second optical system, the group whose spacing in the optical axis direction changes with adjacent groups during zooming is defined as a single lens group.

[0094] According to a 37th aspect of the present invention, in the projection optical system according to the 36th aspect, when the focal length of the 2B lens group is set to f2B and the focal length of the 2C lens group is set to f2C,

[0095] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0096] 0<f2B / |f2C|<0.5 (11).

[0097] A 38th aspect of the present invention is a projection display device comprising the projection optical system according to any one of the 30th to 37th aspects.

[0098] In addition, the terms "including" and "including" in this specification mean that, in addition to the listed constituent elements, the following may also be included: lenses that do not essentially have optical focal length (refractive power), and optical elements other than lenses such as apertures, masks, filters, cover glasses, plane mirrors and prisms, as well as mechanical parts such as lens flanges, lens barrels, camera elements and hand-shake correction mechanisms.

[0099] In this specification, "a group having positive power" means that the group as a whole has positive power, and "a lens component having positive power" means that the lens components as a whole have positive power. Similarly, "a group having negative power" means that the group as a whole has negative power, and "a lens component having negative power" means that the lens components as a whole have negative power. The terms "lens group," "focusing group," and "back focus correction group" in this specification are not limited to structures comprising multiple lenses and may also be structures comprising only a single lens.

[0100] A composite aspheric lens (a lens (e.g., a spherical lens) and an aspheric film formed on the lens are integrated, and the entire lens functions as a single aspheric lens) is used as a single lens and is not considered a cemented lens. Unless otherwise specified, the radius of curvature, the sign of the optical power, and the surface shape related to lenses that include aspheric surfaces use the paraxial region. Unless otherwise specified, the "distance on the optical axis" used in conditional expressions is a geometric distance. The "focal length" used in conditional expressions is the paraxial focal length. The values used in the conditional expressions are based on the d-line.

[0101] The "d-line", "C-line", and "F-line" described in this specification are bright lines. The wavelength of the d-line is considered to be 587.56 nm (nanometers), the wavelength of the C-line is considered to be 656.27 nm (nanometers), and the wavelength of the F-line is considered to be 486.13 nm (nanometers).

[0102] Effects of the Invention

[0103] According to the present invention, it is possible to provide a projection optical system having a wide viewing angle and a long back focus, which is compact and maintains excellent optical performance, and a projection display device including the projection optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 The projection optical system corresponds to Example 1 and is a cross-sectional view showing the structure of the projection optical system and light beams according to one embodiment.

[0105] Figure 2 This is a diagram for explaining symbols of each conditional expression.

[0106] Figure 3 yes Figure 1 A partial enlarged view of the projection optical system.

[0107] Figure 4 This is a diagram for explaining the maximum effective diameter.

[0108] Figure 5 It is a diagram for explaining the amount of change in the tangential image plane.

[0109] Figure 6 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 1.

[0110] Figure 7 It is a cross-sectional view showing the structure of the projection optical system and light beams of Example 2.

[0111] Figure 8 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 2.

[0112] Figure 9 It is a cross-sectional view showing the structure of the projection optical system and light beams of Example 3.

[0113] Figure 10 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 3.

[0114] Figure 11 It is a cross-sectional view showing the structure of the projection optical system and light beams of Example 4.

[0115] Figure 12 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 4.

[0116] Figure 13 It is a cross-sectional view showing the structure of the projection optical system and light beams of Example 5.

[0117] Figure 14 These are diagrams showing various aberrations of the projection optical system of Example 5.

[0118] Figure 15 It is a cross-sectional view showing the structure of the projection optical system and the light beam of Example 6.

[0119] Figure 16 These are diagrams showing various aberrations of the projection optical system of Example 6.

[0120] Figure 17 This is a schematic structural diagram of a projection display device according to one embodiment.

[0121] Figure 18It is a schematic structural diagram of a projection display device according to another embodiment.

[0122] Figure 19 It is a schematic structural diagram of a projection display device according to still another embodiment.

[0123] Explanation of symbols

[0124] 10-Optical system for projection, 11a-11c-Transmissive display element, 12-Dichroic mirror, 13-Dichroic mirror, 14-Cross dichroic prism, 15-Light source, 16a-16c-Converging lens, 18a-18c-Total reflection mirror, 21a-21c-DMD element, 24a-24c-TIR prism, 25-Polarization beam splitter prism, 61-Light source, 62-Color wheel, 63-Light guide optical system, 64-DMD element, 65-TIR prism, 66-Optical system for projection, 67-Screen, 100-Projection display device, 105-Screen, 200-Projection display device, 205-Screen, 210-Optical system for projection, 215-Light source, 600-Projection display device, B0-On-axis beam, B40-Beam, B50-Beam, Bmax-Beam, dAmax-Longest space Air spacer, dFr12-spacer, Dnp-spacer, ED-maximum effective diameter, EDL1-maximum effective diameter, EDp-maximum effective diameter, G1-first optical system, G2-second optical system, G2A-2A lens group, G2B-2B lens group, G2C-2C lens group, G2D-2D lens group, L1a~L2j-lens, LN-N lens component, LP-P lens component, Lx-lens, MI-intermediate image, PP-optical component, Px-position, Scr-screen, Sim-display surface, St-aperture stop, t0-tangential image plane, tB1-tangential image plane, Xa-on-axis beam, Xb1-ray, Xb-off-axis beam, Y40-image height, Y50-image height, Ymax-maximum image height, Z-optical axis, ZFBr-distance, Zp-distance, ΔtB-change. DETAILED DESCRIPTION

[0125] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0126] Figure 1 , there is shown a cross-sectional view of the structure of the projection optical system and a light beam according to one embodiment of the present invention. Figure 1 In FIG, as light beams, the on-axis light beam B0 and the light beam Bmax at the maximum half viewing angle are shown. Figure 1 In the middle, the left side is the magnified side and the right side is the reduced side. Figure 1 The example shown corresponds to the projection optical system of Example 1 described later.

[0127] exist Figure 1 , an example is shown in which a projection optical system is assumed to be mounted on a projection-type display device, and an optical component PP and a display surface Sim of a light valve are arranged on the reduction side of the projection optical system. The light valve is a display element that outputs an optical image, and the optical image is displayed on the display surface Sim in the form of an image. As the light valve, for example, an image display element such as a liquid crystal display element or a DMD (digital micromirror device: registered trademark) can be used. The optical component PP is a component that is assumed to be a filter, cover glass, or color synthesis prism. The optical component PP is a component that does not have optical power. The material, length, and number of components of the optical component PP can be appropriately changed, and a structure in which the optical component PP is omitted is also possible.

[0128] The projection optical system is capable of projecting an image on the reduced-side imaging surface onto the magnified-side imaging surface. For example, the projection optical system mounted on a projection-type display device projects an image displayed on the display surface Sim of a display element onto a screen Scr. Specifically, in a projection-type display device, a light beam imparted with image information on the display surface Sim of the display element enters the projection optical system via an optical component PP, and is projected onto the screen Scr, which serves as a projection surface, by the projection optical system. In this case, the display surface Sim corresponds to the reduced-side imaging surface, and the screen Scr corresponds to the magnified-side imaging surface. The display surface Sim and the screen Scr are located at optically conjugate positions. In addition, in this specification, the "screen Scr" refers to the object onto which the projection image formed by the projection optical system is projected. The screen Scr may be, in addition to a dedicated screen, a wall, floor, ceiling, or outer wall of a room, or a building.

[0129] In this specification, "enlargement side" refers to the screen Scr side of the optical path, and "reduction side" refers to the display surface Sim side of the optical path. In this specification, "enlargement side" and "reduction side" are determined based on the optical path. Furthermore, "adjacent" in relation to the arrangement of component elements indicates proximity in the order of arrangement on the optical path. To avoid redundant descriptions, "from the enlargement side to the reduction side along the optical path" may be referred to as "from the enlargement side to the reduction side."

[0130] The projection optical system of the present invention is configured as a wide-angle optical system with a half viewing angle of 50 degrees or more on the magnification side. According to this structure, an image can be projected with a wide viewing angle. As a more preferred structure, the half viewing angle of the magnification side is set to 55 degrees or more.

[0131] As an example, Figure 1The projection optical system includes a first optical system G1 and a second optical system G2 along the optical path from the magnification side to the reduction side. The second optical system G2 forms an intermediate image M1 between the first optical system G1 and the second optical system G2 and at a position conjugate with the display surface Sim (corresponding to the reduction side imaging surface). The first optical system G1 re-images the intermediate image MI onto the screen Scr (corresponding to the magnification side imaging surface). In other words, Figure 1 The projection optical system is a relay optical system with the second optical system G2 as a relay group. When the focal length of the projection optical system is shortened to achieve a wide angle, if the required optical performance is achieved while ensuring the back focus required in the projection optical system, the lens on the magnification side tends to become huge. By setting it as a relay optical system that forms an intermediate image MI internally, it is possible to suppress the enlargement of the lens and achieve a compact structure despite being an optical system with a wide angle and a long back focus. In addition, Figure 1 In FIG, an intermediate image MI is conceptually shown by a dotted line. Figure 1 The shape of the middle like MI is not necessarily correct.

[0132] As an example, Figure 1 The projection optical system is a zoom lens. The first optical system G1 is fixed relative to the image plane on the reduction side, while the second optical system G2 includes a lens group that moves during zooming. Hereinafter, the lens group that moves during zooming will be referred to as the "moving lens group." By configuring the second optical system G2 to include a moving lens group, rather than the first optical system G1 as a wide-angle system, fluctuations in field curvature and distortion during zooming can be suppressed.

[0133] As an example, Figure 1 The optical systems are constructed as follows. The first optical system G1 includes lenses L1a to L1l in order from the magnification side to the reduction side. The second optical system G2 includes the 2A lens group G2A, the 2B lens group G2B, the 2C lens group G2C, and the 2D lens group G2D in order from the magnification side to the reduction side. The 2A lens group G2A includes lenses L2a to L2d in order from the magnification side to the reduction side. The 2B lens group G2B includes lens L2e. The 2C lens group G2C includes an aperture stop St and lenses L2f to L2i in order from the magnification side to the reduction side. The 2D lens group G2D includes lens L2j. In addition, Figure 1 The aperture stop St shown does not indicate the size or shape, but rather the position in the optical axis direction. This method of illustrating the aperture stop St is the same in the other drawings.

[0134] In addition, in this specification, in the second optical system G2, the group whose optical axis spacing changes with adjacent groups during magnification is defined as one lens group. That is, the "lens group" is a component of the second optical system G2 and is a portion including at least one lens separated by an air gap that changes during magnification. During magnification, the spacing between adjacent lenses within a lens group does not change. During magnification, each lens group unit moves or is fixed. The "lens group" may include components other than lenses without optical power, such as an aperture stop St and / or a plane mirror.

[0135] exist Figure 1 In the example, when changing the magnification, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the imaging surface on the reduction side, and the 2B lens group G2B and the 2C lens group G2C change the distance between each other and move. In this way, by setting the second optical system G2 as a relay group to a 4-group structure, it is advantageous to realize a zoom lens with a wide viewing angle. Usually, among the lenses in the relay group, the lenses on the magnification side and the reduction side tend to be lenses with large diameters. Therefore, when changing the magnification, the 2A lens group G2A on the magnification side and the 2D lens group G2D on the reduction side are fixed, and the 2B lens group G2B and the 2C lens group G2C are set as movable lens groups, thereby miniaturizing the mechanical mechanism for movement. In addition, by fixing the 2D lens group G2D when changing the magnification, the change in telecentricity when changing the magnification can be suppressed. Figure 1 In FIG. 1 , arrows are written below the moving lens groups to indicate the approximate moving directions of the respective groups when zooming from the wide-angle end to the telephoto end.

[0136] exist Figure 1 In the example, lenses L1a to L1c of the first optical system G1 are single lenses with negative optical power, and lens L1d is a single lens with positive optical power. "Single lens" in this specification refers to a single unjoined lens. Also, in this specification, a single lens or a joined lens is referred to as a lens component. Hereinafter, the lens component with positive optical power closest to the magnification side among the lens components included in the projection optical system will be referred to as "P lens component LP". Also, the lens component with negative optical power arranged adjacent to the magnification side of the P lens component LP will be referred to as "N lens component LN". In Figure 1 In the example of , lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN.

[0137] When the P lens component LP is a single lens, the refractive index of the P lens component LP with respect to the d-line is preferably 1.65 or greater. Setting a refractive index of 1.65 or greater makes it easier to ensure the required optical power of the P lens component LP, thereby facilitating correction of various aberrations, particularly astigmatism. To achieve even better performance, the refractive index of the P lens component LP with respect to the d-line is more preferably 1.7 or greater, and even more preferably 1.75 or greater.

[0138] When the N lens component LN is a single lens, the refractive index of the N lens component LN with respect to the d-line is preferably 1.65 or less. Setting the refractive index to 1.65 or less prevents excessive optical power of the N lens component LN, thereby facilitating correction of various aberrations, particularly spherical aberration and field curvature. To achieve even better performance, the refractive index of the N lens component LN with respect to the d-line is more preferably 1.6 or less, and even more preferably 1.57 or less.

[0139] The first optical system G1 preferably includes an aspheric lens. Arranging an aspheric lens within the first optical system G1, which functions as a wide-angle system, facilitates correction of field curvature and distortion. More preferably, the first optical system G1 includes two aspheric lenses. In this case, correction of field curvature and distortion is further facilitated.

[0140] The lens surface closest to the magnification side of the first optical system G1 is preferably an aspheric surface, which is concave toward the magnification side in the paraxial region and has an inflection point where the concave-convex shape changes midway as it moves from the optical axis to the peripheral portion. In this case, it is beneficial to correct distortion aberration in a wide-angle system. In addition, the "lens surface" in this specification refers to the surface of the lens through which the light used for imaging passes. And, the inflection point refers to the point where the surface shape switches from a convex shape to a concave shape, or from a concave shape to a convex shape, that is, the point where the sign of the curvature radius changes. By having an inflection point on the lens surface, the refractive power of the peripheral portion of the lens can be determined without relying on the refractive power of the paraxial region.

[0141] The reduction side of the projection optical system is preferably telecentric. Projection display devices that output high-definition images employ a three-panel system, requiring excellent telecentricity. Furthermore, in recent years, the so-called pixel shifting method, which shifts pixels to achieve a resolution twice or four times the number of pixels in the display element, has become increasingly popular to achieve compact, high-definition projection display devices. To ensure this resolution, a telecentric optical system is preferred.

[0142] Furthermore, the phrase "the reduction side is telecentric" includes the tolerances permitted for practical use within the technical field to which the present invention pertains. Regarding this tolerance, for example, when tracing rays from the magnification side to the reduction side, the angle between the principal ray incident on the reduction-side imaging plane and the optical axis Z can be set within a range of -3 degrees to +3 degrees. In a system that does not include an aperture stop St, when observing the beam from the magnification side toward the reduction side, telecentricity can be determined using the angle bisector between the upper and lower maximum rays in the cross section of the beam converging at a point on the reduction-side imaging plane, instead of the principal ray.

[0143] It is preferred that a focusing group be provided within the projection optical system, and that the focusing group adjusts the focus of the entire image plane by moving along the optical axis Z when the projection distance changes. The "entire image plane" mentioned here refers to, for example, the entire projection image projected onto the screen Scr. By moving the focusing group, it is possible to adjust the position of the conjugate point on the optical axis when the projection distance changes, and to correct the image curvature when the projection distance changes. The "adjustment of the position of the conjugate point" mentioned above includes, for example, focusing. By including such a focusing group in the projection optical system, it is possible to focus while maintaining optical performance up to the periphery of the image plane when the projection distance changes.

[0144] As an example, Figure 1 The projection optical system of the example includes only one focusing group, which includes lenses L1a to L1i. Figure 1 In FIG, brackets and hollow double arrows parallel to the optical axis Z are written below the lens corresponding to the focusing group. Figure 1 In the example above, during the focus adjustment, the spacing between all lenses in the focus group remains unchanged. Furthermore, in the drawings of this application, multiple lenses enclosed in parentheses with arrows indicating movement are shown to move in unison. "Moving in unison" means moving simultaneously in the same direction and by the same amount.

[0145] The focusing group is preferably arranged closest to the magnification side in the projection optical system. In this case, the group structure can be simplified.

[0146] The focusing group is preferably disposed within the first optical system G1. In this case, it is advantageous to correct the tilt of the image plane when the projection distance changes in the ultra-wide-angle lens system.

[0147] In order to ensure the performance when the projection distance changes, the focusing group preferably includes 6 or more lenses. By forming the focusing group with 6 or more lenses, even if the projection optical system includes only one focusing group, it is easy to ensure the performance when the projection distance changes. For example, Figure 1 The focusing group consists of 9 lenses.

[0148] The focusing group preferably includes two or more positive lenses. In this case, it is beneficial to correct the field curvature well. For example, Figure 1 The focusing group consists of 5 negative lenses and 4 positive lenses.

[0149] The lens surface closest to the magnification side of the focusing group is preferably an aspherical surface that is concave toward the magnification side in the paraxial region and has an inflection point where the concave-convex shape changes midway as it moves from the optical axis toward the periphery. This facilitates distortion correction in wide-angle lens systems.

[0150] Preferably, one of the first lens from the zoom-out side of the focus group and the second lens from the zoom-out side is a negative lens, and the other is a positive lens. This helps suppress fluctuations in chromatic aberration of magnification during focus adjustment. If one of the first lens from the zoom-out side of the focus group and the second lens from the zoom-out side of the focus group is a negative lens and the other is a positive lens, these negative and positive lenses can be cemented together. Arranging a cemented lens composed of a negative and positive lens closest to the zoom-out side of the focus group further helps suppress fluctuations in chromatic aberration of magnification during focus adjustment.

[0151] As an example, in Figure 1 In the example, the lens L1i, which is the first lens from the reduction side of the focus group, is a negative lens, and the lens L1h, which is the second lens from the reduction side of the focus group, is a positive lens. Figure 1 In the example of FIG, lens L1i and lens L1h are cemented to each other.

[0152] The lens surface closest to the reduction side of the focusing group is preferably a concave surface. In this case, field curvature during focus adjustment can be effectively corrected.

[0153] Preferably, a back focus correction group is provided within the projection optical system for adjusting the back focus by moving along the optical axis Z. When a uniform focus deviation error occurs from the vicinity of the optical axis to the periphery of the image plane, focusing can be achieved by moving the back focus correction group. The main causes of such errors are believed to be errors on the projection optical system side when the projection optical system is mounted on a projection display device and / or errors on the projection display device side, focus deviation caused by temperature, and the influence of gravity. The back focus correction group is not limited to a structure including multiple lenses and may also be a structure including only a single lens.

[0154] As an example, in Figure 1 In the example of , the back focus correction group includes lens L1j. Figure 1 In FIG, brackets and a black double arrow parallel to the optical axis Z are written below the lens corresponding to the back focus correction group.

[0155] Both the focusing group and the back focus correction group may be arranged in the projection optical system, which facilitates good focus adjustment.

[0156] When both the focusing group and the back focus correction group are disposed within the projection optical system, it is preferred that the focusing group and the back focus correction group be movable independently of each other. By adjusting the position of the conjugate point, correcting for field curvature, and adjusting the back focus separately, the entire image plane can be focused, thereby obtaining a good projected image.

[0157] In the projection optical system of the present invention, preferably, all optical elements with optical power are refractive elements. Typically, in projection optical systems that include reflective optical elements with optical power, light beams near the optical axis reflected by the reflective surfaces of these optical elements are blocked by the projection display device and cannot be used to form the projection image. Therefore, to avoid this shading, the center position of the image on the reduced-side imaging surface is displaced from the optical axis Z of the projection optical system, and this displacement typically increases. Consequently, in projection optical systems that include reflective optical elements with optical power, the size of the reflective surfaces with optical power tends to increase, making miniaturization difficult. In contrast, in projection optical systems that utilize all refractive optical elements with optical power, light beams near the optical axis can still be used to form the projection image, and even with the aforementioned displacement, the displacement can be reduced. Reducing the displacement allows for miniaturization of each optical element, thereby miniaturizing the entire optical system.

[0158] Next, the preferred and possible configurations related to the conditional formulas for the projection optical system of the present invention are described. In the following descriptions of the conditional formulas, identical symbols are used for parts with the same definition to avoid redundant explanations, thereby omitting repeated descriptions of the symbols. Furthermore, to avoid redundant explanations, the "projection optical system of the present invention" is also referred to simply as the "projection optical system." When the projection optical system is a variable magnification optical system, the symbols used in the following conditional formulas refer to values at the wide-angle end.

[0159] The projection optical system preferably satisfies the following conditional formula (1). Here, the maximum image height on the image plane on the reduction side is set to Ymax. The distance on the optical axis from the surface of the optical element with optical focal length closest to the magnification side of the projection optical system to the lens surface of the P lens component LP closest to the magnification side is set to Zp. In addition, the "surface of the optical element with optical focal length" refers to, for example, a lens surface, a non-planar reflective mirror surface, a diffraction surface, etc. As an example, in Figure 1 The maximum image height Ymax is shown in Figure 2 The above-mentioned distance Zp is shown in FIG. Figure 2 Is used to illustrate Figure 1 By satisfying conditional expression (1), the P lens component LP can be arranged at a position effective for miniaturization.

[0160] 1<Zp / Ymax<4 (1)

[0161] To obtain better characteristics, the lower limit of conditional expression (1) is more preferably 1.5, and further preferably 1.7. To obtain better characteristics, the upper limit of conditional expression (1) is more preferably 3, and further preferably 2.5.

[0162] The projection optical system preferably satisfies the following conditional expression (2). Here, the radius of curvature of the lens surface of the P lens component LP closest to the magnification side is set to Rpf. By avoiding the corresponding value of the conditional expression (2) from becoming below the lower limit value, the optical focal length of the lens surface of the P lens component LP closest to the magnification side will not become too strong, so the generation of aberrations can be suppressed. This is beneficial to the correction of various aberrations, especially spherical aberration and image surface curvature. By avoiding the corresponding value of the conditional expression (2) from becoming above the upper limit value, the optical focal length of the lens surface of the P lens component LP closest to the magnification side will not become too weak, so it is beneficial to the correction of high-order aberrations. This makes it easy to miniaturize the lens while appropriately correcting various aberrations. In addition, in this specification, "high order" involving aberrations means 5 orders or more.

[0163] 0.2<Rpf / Ymax<2.3 (2)

[0164] To obtain better characteristics, the lower limit of conditional expression (2) is more preferably 0.5, and further preferably 0.7. To obtain better characteristics, the upper limit of conditional expression (2) is more preferably 2, and further preferably 1.8.

[0165] The projection optical system preferably satisfies the following conditional expression (3). Here, the radius of curvature of the lens surface closest to the reduction side of the N lens component LN is set to Rnr. By preventing the corresponding value of conditional expression (3) from becoming below the lower limit, the optical power of the lens surface closest to the reduction side of the N lens component LN will not become too strong, thereby suppressing the generation of aberrations. This is beneficial for correcting various aberrations, especially spherical aberration and field curvature. By preventing the corresponding value of conditional expression (3) from becoming above the upper limit, the optical power of the lens surface closest to the reduction side of the N lens component LN will not become too weak, thereby facilitating the correction of high-order aberrations. As a result, it is easy to appropriately correct various aberrations while miniaturizing the lens.

[0166] 0.2<Rnr / Ymax<5 (3)

[0167] To obtain better characteristics, the lower limit of conditional expression (3) is more preferably 0.5, and further preferably 0.7. To obtain better characteristics, the upper limit of conditional expression (3) is more preferably 3, and further preferably 2.5.

[0168] The projection optical system more preferably satisfies conditional expressions (1), (2), and (3) simultaneously. By arranging the P lens component LP at a position satisfying conditional expression (1) and configuring the two lens surfaces to face each other with air as the interface, the values of conditional expressions (2) and (3) are avoided from exceeding their upper limits, which contributes to shortening the total length of the optical system and reducing the diameter of the lenses, thereby facilitating miniaturization of the optical system.

[0169] The projection optical system preferably satisfies the following conditional expression (4). Here, the back focus on the reduced side of the air-converted distance of the projection optical system is set to Bf. Avoiding the corresponding value of conditional expression (4) from falling below the lower limit facilitates ensuring a long back focus. Avoiding the corresponding value of conditional expression (4) from falling above the upper limit facilitates miniaturization of the total length of the optical system and the lens diameter.

[0170] 2<Bf / Ymax<8 (4)

[0171] To obtain better characteristics, the lower limit of conditional expression (4) is more preferably 2.5, and further preferably 2.7. To obtain better characteristics, the upper limit of conditional expression (4) is more preferably 5, and further preferably 4.

[0172] The projection optical system preferably satisfies the following conditional formula (5). Here, the image height on the image plane on the reduction side of the light with a half viewing angle of 40 degrees on the magnification side is set to Y40. The image height on the image plane on the reduction side of the light with a half viewing angle of 50 degrees on the magnification side is set to Y50. As an example, Figure 2 , a light beam B40 with a half viewing angle of 40 degrees on the magnification side, an image height Y40 of the light beam B40 on the reduction side imaging surface, a light beam B50 with a half viewing angle of 50 degrees on the magnification side, and an image height Y50 of the light beam B50 on the reduction side imaging surface are shown. Figure 2 In FIG, the angles between the principal rays contained in the light beam B40 and the light beam B50 and the optical axis Z are 40° and 50°, respectively. In projection display devices, even ultra-wide-angle projection optical systems are required to project undistorted images. By satisfying conditional expression (5), it is easy to project undistorted images onto the screen Scr using a wide-angle optical system.

[0173] 1.35<Y50 / Y40<1.5 (5)

[0174] To obtain better characteristics, the lower limit of conditional expression (5) is more preferably 1.37, and further preferably 1.4. To obtain better characteristics, the upper limit of conditional expression (5) is more preferably 1.46, and further preferably 1.44.

[0175] In a configuration where the half viewing angle on the magnification side is 55 degrees or greater, the projection optical system preferably satisfies the following conditional expression (5A). Here, the image height on the image plane on the reduction side of a ray having a half viewing angle on the magnification side of 55 degrees is set to Y55. Satisfying conditional expression (5A) makes it easier to project an image without distortion onto the screen Scr in a wider-angle optical system.

[0176] 1.6<Y55 / Y40<1.8(5A)

[0177] To obtain better characteristics, the lower limit of conditional expression (5A) is more preferably 1.65, and further preferably 1.68. To obtain better characteristics, the upper limit of conditional expression (5A) is more preferably 1.75, and further preferably 1.72.

[0178] The projection optical system preferably satisfies the following conditional expression (6). Here, the distance between the N lens component LN and the P lens component LP on the optical axis is set to Dnp. Figure 3 Shown in the Figure 1 A partial enlarged view of lenses L1a to L1d of the projection optical system shows the aforementioned spacing Dnp as an example. Since the N lens component LN and the P lens component LP are different lens components, Dnp > 0. Furthermore, since Ymax > 0, the lower limit of conditional expression (6) is Dnp / Ymax > 0. Preventing the corresponding value of conditional expression (6) from exceeding the upper limit facilitates correction of spherical aberration.

[0179] 0<Dnp / Ymax<0.1 (6)

[0180] To improve manufacturability, the lower limit of conditional expression (6) is more preferably 0.002, and further preferably 0.004. To obtain better characteristics, the upper limit of conditional expression (6) is more preferably 0.05, and further preferably 0.03.

[0181] The projection optical system preferably satisfies the following conditional expression (7). Here, the radius of curvature of the lens surface closest to the reduction side of the P lens component LP is set to Rpr. Avoiding the corresponding value of conditional expression (7) from falling below the lower limit facilitates correction of spherical aberration. Avoiding the corresponding value of conditional expression (7) from falling above the upper limit facilitates correction of astigmatism.

[0182] 0<(Rpr+Rpf) / (Rpr-Rpf)<2 (7)

[0183] To obtain better characteristics, the lower limit of conditional expression (7) is more preferably 0.2, and further preferably 0.3. To obtain better characteristics, the upper limit of conditional expression (7) is more preferably 1, and further preferably 0.95.

[0184] The projection optical system preferably satisfies the following conditional expression (8). Here, the larger of the maximum effective diameter of the lens surface of the P lens component LP closest to the magnification side and the maximum effective diameter of the lens surface of the P lens component LP closest to the reduction side is set as EDp. As an example, in Figure 3 The maximum effective diameter EDp is shown in FIG. Avoiding the corresponding value of conditional expression (8) from falling below the lower limit value is advantageous for securing the desired F-number. Avoiding the corresponding value of conditional expression (8) from exceeding the upper limit value allows the P lens component LP to be arranged near the pupil position, thereby contributing to miniaturization of the optical system.

[0185] 0.5<EDp / Ymax<2.5 (8)

[0186] To obtain better characteristics, the lower limit of conditional expression (8) is more preferably 1, and further preferably 1.2. To obtain better characteristics, the upper limit of conditional expression (8) is more preferably 2, and further preferably 1.8.

[0187] Here, reference Figure 4 The "maximum effective diameter" in this specification will be explained. Figure 4 is a diagram for illustration. Figure 4 In the , the left side is the magnification side, and the right side is the reduction side. Figure 4 The on-axis beam Xa and off-axis beam Xb passing through the lens Lx are shown in FIG. Figure 4 In the example, the maximum light ray on the upper side of the off-axis beam Xb, that is, the light ray Xb1, is the light ray passing through the outermost side. The "outer side" mentioned here refers to the radial outer side with the optical axis Z as the center, that is, the side away from the optical axis Z. In this specification, the position of the intersection of the light ray passing through the outermost side and the lens surface is the position Px of the maximum effective diameter. And, twice the distance from the position Px of the maximum effective diameter to the optical axis Z becomes the maximum effective diameter ED of the surface on the magnification side of the lens Lx. In addition, in Figure 4 In the example of , the largest ray on the upper side of the off-axis beam Xb is the ray that passes the outermost side. However, which ray becomes the ray that passes the outermost side varies depending on the optical system.

[0188] The projection optical system preferably satisfies the following conditional expression (9). Here, the radius of curvature of the lens surface closest to the magnification side of the N lens component LN is set to Rnf. Avoiding the corresponding value of conditional expression (9) from falling below the lower limit facilitates correction of field curvature. Avoiding the corresponding value of conditional expression (9) from falling above the upper limit facilitates correction of astigmatism.

[0189] -1<(Rnr+Rnf) / (Rnr-Rnf)<0.5 (9)

[0190] To obtain better characteristics, the lower limit of conditional expression (9) is more preferably -0.8, and further preferably -0.7. To obtain better characteristics, the upper limit of conditional expression (9) is more preferably 0.1, and further preferably 0.05.

[0191] The projection optical system preferably satisfies the following conditional formula (10). Here, a group including all lenses closer to the magnification side than the mobile lens group closest to the magnification side in the mobile lens group included in the projection optical system is set as the magnification side fixed group. The longest air gap between the lens surfaces on the optical axis in the magnification side fixed group is set as dAmax. Figure 1 In the example of , the movable lens group closest to the magnification side among the movable lens groups included in the projection optical system is the 2B lens group G2B. Figure 1 In the example of , the magnification side fixed group includes all lenses from lens L1a to lens L2d, and the distance on the optical axis between lens L1l and lens L2a corresponds to the maximum air gap dAmax. As an example, in Figure 2 The maximum air gap dAmax is shown in FIG. By preventing the corresponding value of conditional expression (10) from falling below the lower limit, an appropriate lens spacing can be ensured, thereby facilitating correction of lateral chromatic aberration and field curvature. By preventing the corresponding value of conditional expression (10) from falling above the upper limit, the total length of the optical system can be shortened.

[0192] 0.2<dAmax / Ymax<2.5 (10)

[0193] To obtain better characteristics, the lower limit of conditional expression (10) is more preferably 0.5, and further preferably 1. To obtain better characteristics, the upper limit of conditional expression (10) is more preferably 2, and further preferably 1.5.

[0194] In the second optical system G2, which includes the 2A lens group G2A, the 2B lens group G2B, the 2C lens group G2C and the 2D lens group G2D in sequence along the optical path from the magnification side to the reduction side, and when changing the magnification, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the image plane on the reduction side, and the 2B lens group G2B and the 2C lens group G2C change the distance between each other and move, the projection optical system preferably satisfies the following conditional formula (11). Here, the focal length of the 2B lens group G2B is set to f2B. The focal length of the 2C lens group G2C is set to f2C. In order to miniaturize the projection optical system with a wide viewing angle and a long back focal length, it is preferably set to a structure in which positive optical power is arranged on the reduction side within the projection optical system. Therefore, if the mobile lens group with strong optical power among the mobile lens groups included in the second optical system G2 is set to positive optical power, it is conducive to miniaturization. By preventing the corresponding value of conditional expression (11) from falling below the lower limit, the movable lens group with the strongest refractive power in the movable lens group included in the second optical system G2 can be set to have a positive refractive power, thereby facilitating miniaturization. By preventing the corresponding value of conditional expression (11) from falling above the upper limit, the absolute value of the refractive power of the 2C lens group G2C does not become excessively large relative to the refractive power of the 2B lens group G2B, thereby facilitating effective correction of astigmatism.

[0195] 0<f2B / |f2C|<0.5 (11)

[0196] In order to obtain better characteristics, the upper limit value of conditional expression (11) is more preferably set to 0.3, and further preferably set to 0.2.

[0197] The projection optical system preferably satisfies the following conditional formula (12). Here, the larger of the maximum effective diameter of the magnification side surface of the lens closest to the magnification side of the projection optical system and the maximum effective diameter of the reduction side surface of the lens closest to the magnification side of the projection optical system is set as EDL1. As an example, Figure 3 The maximum effective diameter EDL1 is shown in FIG. The specific gravity of the lens closest to the magnification side of the projection optical system is set to ρL1. By preventing the corresponding value of conditional expression (12) from falling below the lower limit, distortion correction is facilitated. By preventing the corresponding value of conditional expression (12) from falling above the upper limit, in a wide-angle optical system in which the lens closest to the magnification side generally has the largest lens diameter within the optical system, it can contribute to lightweighting of the optical system.

[0198] 0.5<EDL1×ρL1 / Ymax<10 (12)

[0199] To obtain better characteristics, the lower limit of conditional expression (12) is more preferably 1, and further preferably 3. To obtain better characteristics, the upper limit of conditional expression (12) is more preferably 8, and further preferably 6.

[0200] In a configuration in which a back focus correction group for adjusting the back focus by moving along the optical axis Z is arranged in the projection optical system, the projection optical system preferably satisfies at least one of the following conditional expressions (18) and (19). Here, the paraxial lateral magnification of the back focus correction group is set to βB. The synthetic paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is set to βBr. The amount of change in the tangential image plane in the optical axis direction at a half angle of view of 50 degrees when the back focus correction group is moved 0.1×Ymax in the optical axis direction is set to ΔtB. βB, βBr, and ΔtB are set to values when the magnification of the projection optical system is 120 times.

[0201] 0.1<|(1-βB 2 )×βBr 2 |<2 (18)

[0202] 0.7<|(1-βB 2 )×βBr 2 | / ΔtB<1.4 (19)

[0203] By preventing the corresponding value of conditional expression (18) from falling below the lower limit, the amount of movement of the back focus correction group during back focus adjustment can be suppressed, thereby contributing to miniaturization of the optical system. By preventing the corresponding value of conditional expression (18) from falling above the upper limit, the amount of change in back focus per unit movement of the back focus correction group does not become excessive, thereby contributing to suppressing the strictness of fine adjustment of back focus.

[0204] To obtain better characteristics, the lower limit of conditional expression (18) is more preferably set to 0.2, and further preferably to 0.25. To obtain better characteristics, the upper limit of conditional expression (18) is more preferably set to 1.5, and further preferably to 1.

[0205] Conditional expression (19) is a conditional expression for aligning the entire image plane in focusing after adjusting the focal length deviation. By satisfying conditional expression (19), it is easy to align the entire image plane including both the optical axis and the peripheral portion of the image plane.

[0206] To obtain better characteristics, the lower limit of conditional expression (19) is more preferably set to 0.75, and further preferably to 0.8. To obtain better characteristics, the upper limit of conditional expression (19) is more preferably set to 1.3, and further preferably to 1.2.

[0207] As an example, in Figure 5In the diagram, the arrows schematically indicate the change ΔtB. Figure 5 In the figure, the optical axis direction is set to the left and right direction of the figure, the solid line represents the tangential image plane t0 based on the design value, and the single-dot chain line represents the tangential image plane tB1 when the back focus correction group moves 0.1×Ymax in the optical axis direction. Figure 5 ω is the half viewing angle, the position corresponding to the half viewing angle of 0 degrees is indicated by a thin solid line, and the position corresponding to the half viewing angle of 50 degrees is indicated by a dotted line.

[0208] In a configuration in which a focusing group is arranged in a projection optical system for adjusting the focus of the entire image plane when the projection distance changes by moving along the optical axis Z, the projection optical system preferably satisfies at least one of the following conditional expressions (17) and (20). Here, the paraxial lateral magnification of the focusing group is set to βFF. The synthetic paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is set to βFFr. The amount of change in the tangential image plane in the optical axis direction at a half angle of view of 50 degrees when the focusing group moves 0.1×Ymax in the optical axis direction is set to ΔtFF. ββFF, βFFr, and ΔtFF are set to values when the magnification of the projection optical system is 120 times.

[0209] 0.02<(1-βFF 2 )×βFFr 2 <0.2 (17)

[0210] 0.1<((1-βFF 2 )×βFFr 2 ) / ΔtFF<0.5 (20)

[0211] Avoiding the corresponding value of conditional expression (17) from being below the lower limit value facilitates focusing near the optical axis. Avoiding the corresponding value of conditional expression (17) from being above the upper limit value facilitates focusing with a good balance on the optical axis and the periphery of the image plane.

[0212] To obtain better characteristics, the lower limit of conditional expression (17) is more preferably set to 0.03, and further preferably to 0.05. To obtain better characteristics, the upper limit of conditional expression (17) is more preferably set to 0.15, and further preferably to 0.13.

[0213] Conditional expression (20) is a conditional expression for achieving a well-balanced focus on the optical axis and the peripheral portion of the image plane when the projection distance changes in a wide-angle lens system. Satisfying conditional expression (20) facilitates achieving a well-balanced focus on both the optical axis and the peripheral portion of the image plane.

[0214] To obtain better characteristics, the lower limit of conditional expression (20) is more preferably set to 0.2, and further preferably to 0.25. To obtain better characteristics, the upper limit of conditional expression (20) is more preferably set to 0.4, and further preferably to 0.35.

[0215] In a structure in which a focusing group for adjusting the focus of the entire image plane when the projection distance changes by moving along the optical axis Z and a back focus correction group for adjusting the back focus by moving along the optical axis Z are arranged in the projection optical system, the projection optical system preferably satisfies both of the above-mentioned conditional expressions (17) and (18).

[0216] In the case where the focusing group includes six or more lenses and is arranged on the closest magnification side of the projection optical system and has a structure in which the spacing between all lenses in the focusing group remains unchanged during focus adjustment, the projection optical system preferably satisfies at least one of the following conditional expressions (13) and (14). Here, the paraxial lateral magnification of the focusing group is set to βF. The synthetic paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is set to βFr. The amount of change in the tangential image plane in the optical axis direction at a half angle of view of 50 degrees when the focusing group moves 0.1×Ymax along the optical axis is set to ΔtF. βF, βFr, and ΔtF are set to values when the magnification of the projection optical system is 120 times.

[0217] 0.02<(1-βF 2 )×βFr 2 <0.2 (13)

[0218] 0.1<((1-βF 2 )×βFr 2 ) / ΔtF<0.5 (14)

[0219] Avoiding the corresponding value of conditional expression (13) from being below the lower limit value facilitates focusing near the optical axis. Avoiding the corresponding value of conditional expression (13) from being above the upper limit value facilitates focusing with a good balance on the optical axis and the periphery of the image plane.

[0220] To obtain better characteristics, the lower limit of conditional expression (13) is more preferably set to 0.03, and further preferably to 0.05. To obtain better characteristics, the upper limit of conditional expression (13) is more preferably set to 0.15, and further preferably to 0.13.

[0221] Conditional expression (14) is a conditional expression for achieving a well-balanced focus on the optical axis and the periphery of the image plane when the projection distance changes in a wide-angle lens system. Satisfying conditional expression (14) facilitates achieving a well-balanced focus on both the optical axis and the periphery of the image plane.

[0222] To obtain better characteristics, the lower limit of conditional expression (14) is more preferably set to 0.2, and further preferably to 0.25. To obtain better characteristics, the upper limit of conditional expression (14) is more preferably set to 0.4, and further preferably to 0.35.

[0223] In a configuration in which one of the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is a negative lens and the other is a positive lens, the projection optical system preferably satisfies the following conditional expression (15). Here, the interval on the optical axis between the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is set to dFr12. As an example, in Figure 2 The interval dFr12 is shown in . Satisfying the conditional expression (15) is advantageous in suppressing the variation of the chromatic aberration of magnification during focus adjustment.

[0224] 0≤dFr12 / Ymax<0.1 (15)

[0225] In a configuration in which both a focusing group and a back focus correction group are arranged in a projection optical system, the projection optical system preferably satisfies the following conditional expression (16). Here, the distance on the optical axis from the lens surface closest to the magnification side of the first optical system G1 to the lens surface closest to the reduction side among the lens surfaces included in the focusing group and the back focus correction group is denoted as ZFBr. As an example, Figure 2 The distance ZFBr is shown in FIG. By preventing the corresponding value of conditional expression (16) from falling below the lower limit, it is easy to ensure space for arranging both the focus group and the back focus correction group. By preventing the corresponding value of conditional expression (16) from falling above the upper limit, the focus group and the back focus correction group are not positioned too close to the zoom-out side, which helps ensure good operability.

[0226] 5<ZFBr / |f|<20 (16)

[0227] To obtain better characteristics, the lower limit of conditional expression (16) is more preferably set to 7, and further preferably to 10. To obtain better characteristics, the upper limit of conditional expression (16) is more preferably set to 19, and further preferably to 15.

[0228] Including the structures related to the conditional expressions, the preferred structures and possible structures can be arbitrarily combined within the scope of non-contradiction, and are preferably appropriately selected and adopted according to the required specifications. Various modifications can be made within the scope of not departing from the main purpose of the technology of the present invention. For example, in the technology of the present invention, the number of lenses included in each group and each optical system and the shape of the lenses can be different. Figure 1 The fixed group, moving lens group, focusing group and back focus correction group during zooming can be different from Figure 1 The examples are different.

[0229] exist Figure 1 In the example, the back focus correction group is positioned closer to the reduction side than the focusing group. More specifically, the back focus correction group is positioned adjacent to the focusing group. However, the technology of the present invention also allows for a configuration in which the focusing group and the back focus correction group are not adjacent. In this case, the back focus correction group can be positioned adjacent to the reduction side of the intermediate image MI.

[0230] The back focus correction group can be configured to include a single lens. More specifically, the back focus correction group can be configured to include a single positive lens. Alternatively, the back focus correction group can be configured to include three lenses. For example, the back focus correction group can be configured to include a single negative lens and two positive lenses.

[0231] According to the above, a preferred embodiment of the present invention involves a projection optical system that projects an image on the reduction side imaging surface onto the magnification side imaging surface, wherein the half viewing angle on the magnification side is greater than 50 degrees, and when one lens component is set as a single lens or a cemented lens, the projection optical system includes: a lens component with positive focal length closest to the magnification side among the lens components included in the projection optical system, namely, a P lens component LP, and a lens component with negative focal length arranged adjacent to the magnification side of the P lens component LP, namely, an N lens component LN, and the projection optical system satisfies the above-mentioned conditional expressions (1), (2), (3), (4), and (5).

[0232] Another preferred embodiment of the present invention involves a projection optical system that includes a first optical system G1 and a second optical system G2 in sequence along the optical path from the magnification side to the reduction side, wherein the second optical system G2 forms an intermediate image MI between the first optical system G1 and the second optical system G2 and at a position conjugate with the reduction side imaging surface, and the first optical system G1 re-images the intermediate image MI on the magnification side imaging surface. A focusing group is arranged on the closest magnification side of the projection optical system, and the focusing group includes more than 6 lenses and adjusts the focus of the entire image surface when the projection distance changes by moving along the optical axis Z. During the focus adjustment, the intervals between all lenses in the focusing group remain unchanged.

[0233] Another preferred embodiment of the present invention involves a projection optical system that includes a first optical system G1 and a second optical system G2 in sequence along the optical path from the magnification side to the reduction side, wherein the second optical system G2 forms an intermediate image M1 between the first optical system G1 and the second optical system G2 and at a position conjugate with the reduction side imaging surface, and the first optical system G1 re-images the intermediate image M1 on the magnification side imaging surface. A focusing group and a back focus correction group are arranged in the projection optical system, and the focusing group adjusts the focus of the entire image surface when the projection distance changes by moving along the optical axis Z, and the back focus correction group adjusts the back focus by moving along the optical axis Z, and the projection optical system satisfies the above-mentioned conditional formula (16).

[0234] Next, embodiments of the projection optical system of the present invention will be described with reference to the accompanying drawings. To avoid the complexity of the description and drawings associated with increasing reference numerals, reference numerals for the lenses, lens groups, and optical systems in the cross-sectional views of each embodiment are used independently for each embodiment. Therefore, even if the same reference numerals are used in the drawings of different embodiments, they do not necessarily represent identical structures.

[0235] [Example 1]

[0236] The structure of the projection optical system and the cross-sectional view of the light beam of Example 1 are shown in FIG. Figure 1 The diagrammatic representation and structure have been described above, so some repeated descriptions are omitted here. The projection optical system of Example 1 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive refractive power, a 2B lens group G2B having positive refractive power, a 2C lens group G2C having positive refractive power, and a 2D lens group G2D having positive refractive power.

[0237] Regarding the projection optical system of Example 1, basic lens data is shown in Tables 1A and 1B, specifications and variable surface spacing during zooming are shown in Table 2, variable surface spacing during focusing is shown in Table 3, and aspheric coefficients are shown in Table 4. To avoid bloating one table, the basic lens data is presented in two tables, Table 1A and Table 1B. Table 1A shows the first optical system G1, and Table 1B shows the second optical system G2.

[0238] The table of basic lens data is as follows. The Sn column shows the surface numbers, with the surface closest to the magnification side as the first surface and increasing in number toward the reduction side. The R column shows the radius of curvature of each surface. The D column shows the optical axis spacing between each surface and the surface adjacent to its reduction side. The Nd column shows the refractive index of each component with respect to the d-line. The νd column shows the Abbe number of each component based on the d-line. The ED column shows the maximum effective diameter of each surface for the lens closest to the magnification side and the P lens component LP.

[0239] In the table of basic lens data, the sign of the curvature radius of the surface with the convex shape facing the magnification side is set to positive, and the sign of the curvature radius of the surface with the convex shape facing the reduction side is set to negative. The surface number column corresponding to the aperture stop St lists the surface number and the term (St). The table of basic lens data also shows the optical component PP. The value at the bottom of column D of the table is the distance between the surface closest to the reduction side in the table and the display surface Sim. The variable surface spacing during magnification is marked with the symbol DD[], and the magnification side surface number of the spacing is indicated in [].

[0240] Table 2 shows the zoom ratio Zr, the absolute value of the focal length |f|, the back focus Bf in terms of air-equivalent distance, the F-number FNo., the maximum full angle of view 2ω, and the distance between the variable surfaces during zooming, all based on the d-line. The [°] in the 2ω column indicates the unit is degrees. In Table 2, the columns labeled "WIDE," "MIDDLE," and "TELE" show the values for the wide-angle end, intermediate focal length, and telephoto end, respectively.

[0241] In Example 1, when the projection distance changes, focusing is performed by changing the distance between the 17th and 18th surfaces. Table 3 shows the variable surface distances when focusing at various projection distances. The projection distance is the distance from the magnified side imaging surface (at Figure 1 The distance on the optical axis corresponds to the screen (Scr) to the lens surface closest to the magnification side.

[0242] In the basic lens data, the surface number of the aspheric surface is marked with an * mark, and the value of the paraxial curvature radius is recorded in the curvature radius column of the aspheric surface. In Table 4, the surface number of the aspheric surface is shown in the Sn row, and the numerical value of the aspheric coefficient of each aspheric surface is shown in the KA and Am rows. In addition, m in Am is an integer greater than 3 and varies depending on the surface. For example, on the first surface of Example 1, m = 3, 4, 5, ... 20. The numerical value of the aspheric coefficient of Table 4 "E±n" (n: integer) means "×10 ±n KA and Am are aspherical coefficients in the aspherical formula represented by the following formula.

[0243] Zd=C×h2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+∑Am×h m

[0244] in,

[0245] Zd: depth of aspheric surface (the length of the perpendicular line from a point on the aspheric surface at height h to a plane tangent to the vertex of the aspheric surface and perpendicular to the optical axis Z);

[0246] h: Height (the distance from the optical axis Z to the lens surface);

[0247] C: the reciprocal of the paraxial curvature radius;

[0248] KA, Am: aspheric coefficients,

[0249] The aspheric ∑ represents the sum related to m.

[0250] In the data in each table, degrees are used as the unit of angle, and mm (millimeter) is used as the unit of length. However, since optical systems can be used at both magnified and reduced scales, other appropriate units may be used. Furthermore, the values in the following tables are rounded to the specified number of decimal places.

[0251] [Table 1A] Example 1

[0252] Sn R D Nd ν d ED *1 -18.7529 4.6414 1.53638 56.09 50.7 *2 -47.9264 5.5314 41.3 3 86.0793 0.9283 1.60311 60.64 4 10.9830 7.3525 5 -27.3343 0.7589 1.51742 52.43 6 15.7504 0.0847 7 16.2239 5.8971 1.83481 42.72 16.7 8 -37.0006 4.3415 15.2 9 -10.3255 2.2345 1.80518 25.46 10 -89.9292 0.1693 *11 153.2666 4.9460 1.58313 59.38 *12 -11.1635 0.1680 13 -98.1504 5.6831 1.49700 81.61 14 -13.9252 0.1694 15 23.8746 5.6060 1.43700 95.10 16 -38.5119 0.7587 1.84666 23.78 17 33.8526 11.8860 18 59.1568 6.4743 1.80420 46.50 19 -49.2869 0.4228 20 20.9556 6.1554 1.80420 46.50 21 60.4191 2.9031 22 -110.8739 0.8433 1.51680 64.20 23 25.2741 13.2159

[0253] [Table 1B] Example 1

[0254] Sn R D Nd vd 24 -16.2790 2.1579 1.51680 64.20 25 78.2294 4.1671 26 -41.6115 5.0326 1.84666 23.78 27 -22.4603 1.3793 28 60.5566 7.7750 1.77250 49.62 29 -43.2696 2.9629 30 33.4323 0.8861 1.80518 25.46 31 23.5155 DD

[31] 32 55.5358 2.1906 1.83481 42.72 33 -100.5849 DD

[33] 34(St) 30.9398 1.0162 1.56732 42.82 35 19.4457 5.4838 36 -16.6916 0.7165 1.84666 23.78 37 -674.1161 0.1879 38 -163.7848 6.5325 1.49700 81.61 39 -18.7884 1.5699 40 64.0741 4.0249 1.49700 81.61 41 -34.6927 DD

[41] ] 42 40.4952 3.5412 1.84666 23.78 43 2363.1072 11.4473 44 ∞ 26.5148 1.51680 64.20 45 ∞ 0.8689

[0255] [Table 2]

[0256] Example 1

[0257] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 6.17 6.36 6.78 Bf 29.7 29.7 29.7 FNo. 1.81 1.83 1.85 2ω[°] 116.4 114.8 111.6 DD

[31] 28.05 26.38 23.25 DD

[33] 4.48 4.86 6.36 DD

[41] 12.49 13.79 15.41

[0258] [Table 3] Example 1

[0259] Projection distance 725.7 543.9 3628 The gap between face 17 and face 18 11.8860 12.0698 11.4416

[0260] [Table 4]

[0261] Example 1

[0262] Sn 1 2 KA -3.3984076E-01 3.2606567E+00 A3 -1.1533329E-03 -9.5623401E-04 A4 8.4795366E-04 7.4016254E-04 A5 -8.7274695E-05 -6.2685288E-05 A6 1.5004900E-06 -3.0169668E-06 A7 4.1884776E-07 9.2830841E-07 A8 -3.1043653E-08 -4.5929568E-08 A9 -3.0934931E-10 -3.0996297E-09 A10 1.1882682E-10 3.6536814E-10 A11 -2.9410201E-12 -1.3422567E-13 A12 -1.9441646E-13 -1.2088474E-12 A13 9.8268202E-15 2.9777959E-14 A14 1.0948402E-16 1.9025081E-15 A15 -1.3552578E-17 -7.9815510E-17 A16 7.5079767E-20 -1.2451577E-18 A17 9.0235272E-21 8.9910364E-20 A18 -1.2502550E-22 -1.5838152E-22 A19 —2.3881645E-24 —3.7737995E-23 A20 4.5122192E-26 3.9154743E-25

[0263] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -1.1548980E-04 4.4205676E-05 A5 8.1318777E-06 1.5305271E-05 A6 2.3862847E-06 -4.3285372E-06 A7 -4.3543592E-07 7.1192275E-07 A8 9.8647737E-09 -1.1617508E-08 A9 3.3697300E-09 -6.1444535E-09 A10 -1.8883031E-10 5.1744340E-10

[0264] Figure 6, which shows various aberration diagrams of the projection optical system of Example 1 when the projection distance is 725.7 mm (millimeter). Figure 6 In the figure, the upper section marked with "WIDE" shows aberrations at the wide-angle end state, the middle section marked with "MIDDLE" shows aberrations at the intermediate focal length state, and the lower section marked with "TELE" shows aberrations at the telephoto end state. Figure 6 In the figure, spherical aberration, astigmatism, distortion, and lateral chromatic aberration are shown from the left. In the spherical aberration diagram, aberrations related to the d-line, C-line, and F-line are shown by solid lines, long dashed lines, and short dashed lines, respectively. In the astigmatism diagram, aberrations related to the d-line in the sagittal direction are shown by solid lines, and aberrations related to the d-line in the meridional direction are shown by short dashed lines. In the distortion diagram, aberrations related to the d-line are shown by solid lines. In the lateral chromatic aberration diagram, aberrations related to the C-line and F-line are shown by long dashed lines and short dashed lines, respectively. In the spherical aberration diagram, the F value is shown after "FNo.=". In the other aberration diagrams, the value of the maximum half angle of view is shown after "ω=". The unit of the horizontal axis of the aberration diagrams other than the distortion diagram is mm (millimeter).

[0265] Unless otherwise specified, the symbols, meanings, description methods, and illustration methods of the data related to the above-mentioned embodiment 1 are basically the same in the following embodiments, so repeated descriptions are omitted. The screen Scr is omitted in the cross-sectional views of the following embodiments.

[0266] [Example 2]

[0267] The structure of the projection optical system and the cross-sectional view of the light beam of Example 2 are shown in FIG. Figure 7 The projection optical system of Example 2 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive focal power, a 2B lens group G2B having positive focal power, a 2C lens group G2C having positive focal power, and a 2D lens group G2D having positive focal power. When changing magnification, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the display surface Sim, and the 2B lens group G2B and the 2C lens group G2C change the distance between them and move.

[0268] The first optical system G1 includes lenses L1a to L1l, in order from magnification to reduction. The 2A lens group G2A includes lenses L2a to L2d, in order from magnification to reduction. The 2B lens group G2B includes lens L2e. The 2C lens group G2C includes, in order from magnification to reduction, an aperture stop St and lenses L2f to L2i. The 2D lens group G2D includes lens L2j. Lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN. The focusing group includes lenses L1a to L1i. The back focus correction group includes lens L1j.

[0269] Regarding the projection optical system of Example 2, basic lens data are shown in Tables 5A and 5B, specifications and variable surface spacing during zooming are shown in Table 6, variable surface spacing during focusing is shown in Table 7, aspheric coefficients are shown in Table 8, and various aberration diagrams are shown in Table 9. Figure 8 Each aberration diagram is a diagram obtained when the projection distance is 725.7 mm (millimeter).

[0270] [Table 5A]

[0271] Example 2

[0272] Sn R D Nd νd ED *1 -18.7529 4.6420 1.53638 56.09 48.40 *2 -53.6187 5.2411 38.1 3 84.0537 0.8431 1.58913 61.25 4 10.6571 6.9837 5 -28.1221 0.7588 1.51742 52.43 6 13.4634 0.0847 7 13.7793 5.6062 1.83481 42.72 15.60 8 -45.5846 4.8379 14 9 -9.8378 1.8318 1.80518 25.46 10 -80.3381 0.1680 *11 124.7030 5.1469 1.58313 59.38 *12 -10.7709 0.1681 13 -155.2206 5.8778 1.49700 81.61 14 -14.1795 0.1694 15 23.8896 6.1221 1.43700 95.10 16 -28.8733 0.7588 1.84666 23.78 17 37.3324 10.6122 18 54.7048 6.2003 1.87070 40.73 19 -53.6262 0.4212 20 21.1550 5.7863 1.80420 46.50 21 64.3645 2.8176 22 -97.9560 0.8431 1.51680 64.20 23 25.4285 12.5906

[0273] [Table 5B] Example 2

[0274] Sn R D Nd ν d 24 -15.6618 3.6952 1.51680 64.20 25 80.3302 4.2247 26 -39.5458 4.3209 1.92286 20.88 27 -22.9169 1.7461 28 69.1650 7.7775 1.77250 49.62 29 -39.9179 3.4055 30 34.7983 0.8432 1.80518 25.46 31 24.5641 DD

[31] 32 59.5554 2.1264 1.83481 42.72 33 -105.6767 DD

[33] 34(St) 31.6945 0.7587 1.58144 40.75 35 20.4322 5.4850 36 -17.9939 0.7165 1.84666 23.78 37 150.6574 0.1012 38 222.0404 4.5030 1.49700 81.61 39 -19.6808 3.0116 40 69.9247 4，2293 1.49700 81.61 41 -30.1856 DD

[41] 42 42.5432 3.3924 1.92286 20.88 43 ∞ 11.4473 44 ∞ 26.5148 1.51680 64.20 45 ∞ 0.8645

[0275] [Table 6] Example 2

[0276] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 6.16 6.36 6.78 Bf 29.7 29.7 29.7 FNo. 1.82 1.84 1.90 2ω[°] 116.6 115.0 111.8 DD

[31] 27.82 26.11 22.90 DD

[33] 4.72 5.26 7.15 DD

[41] 14.41 15.58 16.91

[0277] [Table 7]

[0278] Example 2

[0279] Projection distance 725.7 543.9 3628 The gap between face 17 and face 18 10.6122 10.7906 10.1815

[0280] [Table 8]

[0281] Example 2

[0282] Sn 1 2 KA -3.8830039E-01 3.1728047E+00 A3 -1.2805380E-03 -1.0037911E-03 A4 9.1761293E-04 7.9324991E-04 A5 -9.6009302E-05 -6.9949142E-05 A6 1.6832339E-06 -2.9763575E-06 A7 4.7708119E-07 1.0615030E-06 A8 -3.6139672E-08 -6.2753494E-08 A9 -3.5913752E-10 -3.0983201E-09 A10 1.4410229E-10 4.9805128E-10 A11 -3.6874415E-12 -5.7748607E-12 A12 -2.4510294E-13 -1.6572325E-12 A13 1.2809792E-14 6.2856142E-14 A14 1.4127819E-16 2.4457524E-15 A15 -1.8419313E-17 -1.6156227E-16 A16 1.0869476E-19 -9.2148134E-19 A17 1.2794035E-20 1.8726091E-19 A18 -1.8381311E-22 -1.5465660E-21 A19 -3.5332510E-24 -8.2602574E-23 A20 6.8930882E-26 1.2959499E-24

[0283] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000g+00 A4 -1.1236836E-04 9.5732039E-06 A5 -4.1195200E-07 3.5470350E-05 A6 4.7690386E-06 -9.4457094E-06 A7 -6.5125990E-07 1.2102930E-06 A8 -4.1142098E-09 1.0767388E-08 A9 6.9360694E-09 -1.3908562E-08 A10 -3.5540008E-10 9.4575778E-10

[0284] [Example 3]

[0285] The structure of the projection optical system and the cross-sectional view of the light beam of Example 3 are shown in FIG. Figure 9The projection optical system of Example 3 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive focal length, a 2B lens group G2B having positive focal length, a 2C lens group G2C having positive focal length, and a 2D lens group G2D having positive focal length. When changing magnification, the 2A lens group 62A and the 2D lens group G2D are fixed relative to the display surface Sim, and the 2B lens group G2B and the 2C lens group G2C change the distance between them and move.

[0286] The first optical system G1 includes lenses L1a to L1l, in order from the magnification side to the reduction side. The 2A lens group G2A includes lenses L2a to L2d, in order from the magnification side to the reduction side. The 2B lens group G2B includes lens L2e. The 2C lens group G2C includes lens L2f, an aperture stop St, and lenses L2g to L2i, in order from the magnification side to the reduction side. The 2D lens group G2D includes lens L2j. Lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN. The focusing group includes lenses L1a to L1i. The back focus correction group includes lens L1j.

[0287] Regarding the projection optical system of Example 3, basic lens data are shown in Tables 9A and 9B, specifications and variable surface spacing during zooming are shown in Table 10, variable surface spacing during focusing is shown in Table 11, aspheric coefficients are shown in Table 12, and various aberration diagrams are shown in Table 13. Figure 10 Each aberration diagram is a diagram obtained when the projection distance is 725.7 mm (millimeter).

[0288] [Table 9A] Example 3

[0289] Sn R D Nd ν d ED *1 -18.7529 4.6414 1.53638 56.09 48.4 *2 -74.9352 5.4993 36.7 3 59.1891 0.8446 1.58913 61.25 4 10.4117 6.6758 5 -30.9846 0.7587 1.51742 52.43 6 9.3132 0.0849 7 9.4265 5.9690 1.83481 42.72 15.1 8 -217.9277 4.7350 13.6 9 -8.0403 0.7587 1.80518 25.46 10 -40.2003 0.1680 *11 101.7193 5.7713 1.58313 59.38 *12 -9.7068 0.1853 13 132.5354 5.2605 1.49700 81.61 14 -18.5377 0.1694 15 28.1594 6.6135 1.43700 95.10 16 -20.7690 0.0923 17 -20.2839 0.7588 1.84666 23.78 18 90.7447 9.8312 19 105.6652 4.9569 1.87070 40.73 20 -43.7126 1.2954 21 20.7547 5.9933 1.80420 46.50 22 77.8797 3.0352 23 -65.3179 0.8431 1.51680 64.20 24 30.8569 12.9230

[0290] [Table 9B]

[0291] Example 3

[0292] Sn R D Nd νd 25 -16.5303 4.0399 1.51680 64.20 26 85.9226 4.7883 27 -32.1354 3.7272 1.92286 20.88 28 -21.4004 2.4356 29 65.3414 7.6625 1.77250 49.62 30 -42.3548 5.8237 31 29.9440 0.8431 1.80518 25.46 32 22.2010 DD

[32] 33 56.8775 2.1019 1.83481 42.72 34 -123.5828 DD

[34] 35 33.1923 0.7593 1.58144 40.75 36 21.5741 1.7664 37(St) ∞ 3.7200 38 -19.5633 0.7165 1.84666 23.78 39 78.7194 0.1954 40 128.6381 3.7066 1.49700 81.61 41 -21.6064 3.5243 42 70.7734 4.4661 1.49700 81.61 43 -27.2081 DD

[43] 44 41.8786 3.4214 1.92286 20.88 45 ∞ 11.4473 46 ∞ 26.5148 1.51680 64.20 47 ∞ 0.8637

[0293] [Table 10]

[0294] Example 3

[0295] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 6.16 6.36 6.78 Bf 29.7 29.7 29.7 FNo. 1.82 1.84 1.90 2ω[°] 116.4 114.8 111.6 DD

[32] 24.24 22.52 19.27 DD

[34] 4.81 5.45 7.50 DD

[43] 15.09 16.17 17.38

[0296] [Table 11]

[0297] Example 3

[0298] Projection distance 725.7 543.9 3628 The gap between 18 and 19 faces 9.8312 10.0113 9.3962

[0299] [Table 12]

[0300] Example 3

[0301] Sn 1 2 KA -1.8787004E-01 1.5313982E+00 A3 -9.1118321E-04 -8.6409839E-04 A4 8.5423722E-04 8.0801519E-04 A5 -9.1328357E-05 -8.0232637E-05 A6 1.7766167E-06 -2.3556420E-06 A7 4.3643322E-07 1.1874251E-06 A8 -3.4098441E-08 -7.6818452E-08 A9 -2.6398508E-10 -3.6757191E-09 A10 1.3153705E-10 6.1100310E-10 A11 -3.5507753E-12 -4.9996608E-12 A12 —2.1542426E-13 -2.1607291E-12 A13 1.1784157E-14 6.6761497E-14 A14 1.1149173E-16 3.7529017E-15 A15 -1.6512913E-17 -1.7898112E-16 A16 1.1183012E-19 -2.9062684E-18 A17 1.1226366E-20 2.1402386E-19 A18 —1.6840440E-22 6.5621714E-23 A19 -3.0399651E-24 -9.7089875E-23 A20 6.0908390E-26 7.5469033E-25

[0302] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -1.0986039E-04 1.9591337E-05 A5 -7.0205425E-07 2.4738606E-05 A6 5.3213325E-06 -6.5949565E-06 A7 -7.7647293E-07 9.7780144E-07 A8 4.0730189E-09 -4.3271310E-09 A9 8.7147527E-09 -1.0858430E-08 A10 -6.1058642E-10 9.2662172E-10

[0303] [Example 4]

[0304] The structure of the projection optical system and the cross-sectional view of the light beam of Example 4 are shown in FIG. Figure 11 The projection optical system of Example 4 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive focal power, a 2B lens group G2B having positive focal power, a 2C lens group G2C having negative focal power, and a 2D lens group G2D having positive focal power. When changing magnification, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the display surface Sim, and the 2B lens group G2B and the 2C lens group G2C change the distance between them and move.

[0305] The first optical system G1 comprises lenses L1a to L1l, in order from magnification to reduction. The 2A lens group G2A comprises lenses L2a to L2d, in order from magnification to reduction. The 2B lens group G2B comprises lens L2e. The 2C lens group G2C comprises lens L2f, an aperture stop St, and lenses L2g to L2i, in order from magnification to reduction. The 2D lens group G2D comprises lens L2j. Lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN. The focusing group comprises lenses L1a to L1i. The back focus correction group comprises lenses L2a to L2c.

[0306] Regarding the projection optical system of Example 4, basic lens data are shown in Tables 13A and 13B, specifications and variable surface spacing during zooming are shown in Table 14, variable surface spacing during focusing is shown in Table 15, aspheric coefficients are shown in Table 16, and various aberration diagrams are shown in Table 17. Figure 12 Each aberration diagram is a diagram obtained when the projection distance is 725.7 mm (millimeter).

[0307] [Table 13A] Example 4

[0308] Sn R D Nd ν d ED *1 -18.7529 4.6413 1.53638 56.09 48.4 *2 -45.9924 4.8206 39.5 3 41.5916 0.8444 1.69680 55.53 4 10.0089 6.4219 5 -30.0128 0.7602 1.53172 48.84 6 12.0645 0.1685 7 10.6030 8.4794 1.77250 49.60 14.9 8 -65.5750 2.6069 10.9 9 -8.5901 1.4513 1.80518 25.46 10 -51.0697 0.1680 *11 -377.3223 4.7479 1.58313 59.38 *12 -10.4166 0.1681 13 125.5715 6.1503 1.49700 81.61 14 -15.2243 0.1693 15 25.9137 6.0162 1.43700 95.10 16 -29.4194 0.0846 17 -28.4534 0.8432 1.84666 23.78 18 56.6860 9.9589 19 55.6880 5.7456 1.83481 42.74 20 -52.9663 0.1683 21 20.1157 5.5405 1.83481 42.74 22 57.2422 3.1866 23 -60.9309 0.8439 1.56883 56.36 24 29.5783 13.1573

[0309] [Table 13B] Example 4

[0310] Sn R D Nd ν d 25 -14.8780 0.8447 1.65844 50.88 26 -220.2393 3.8371 27 -24.6129 5.4428 1.80518 25.46 28 -18.0175 0.1688 29 68.4756 7.6306 1.77250 49.60 30 -42.4780 10.2598 31 29.0945 1.0032 1.51742 52.43 32 21.2460 DD

[32] 33 30.7203 2.9149 1.85883 30.00 34 -2209.6345 DD

[34] 35 22.6041 0.9073 1.60342 38.03 36 13.7945 2.5697 37(St) ∞ 5.5164 38 -14.6378 0.7587 1.84666 23.78 39 72.2727 0.1021 40 87.7290 4.6591 1.49700 81.61 41 -17.5434 0.1688 42 73.1826 5.4122 1.49700 81.61 43 -21.2907 DD

[43] 44 65.4735 3.7017 1.89286 20.36 45 -106.9662 11.4473 46 ∞ 26.5148 1.51680 64.20 47 ∞ 0.8635

[0311] [Table 14]

[0312] Example 4

[0313] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 6.16 6.36 6.77 Bf 29.7 29.7 29.7 FNo. 1.81 1.82 1.85 2ω[.] 116.6 115.0 111.6 DD

[32] 22.13 20.60 17.64 DD

[34] 3.33 3.69 4.61 DD

[43] 17.18 18.35 20.40

[0314] [Table 15] Example 4

[0315] Projection distance 725.7 543.9 3628 The gap between 18 and 19 faces 9.9589 10.1191 9.5715

[0316] [Table 16]

[0317] Example 4

[0318] Sn 1 2 KA -5.5505211E-02 1.4214983E+00 A3 -7.9062797E-04 -5.0269799E-04 A4 7.7309963E-04 5.9927485E-04 A5 -7.3245iOOE-05 -3.4381457E-05 A6 7.2880349E-07 -3.7122135E-06 A7 3.4057845E-07 4.9029604E-07 A8 -2.0417666E-08 -4.4417501E-09 A9 -3.7190726E-10 -1.8983737E-09 A10 7.4985121E-11 7.1110085E-11 A11 -1.3702913E-12 3.5919273E-12 A12 -1.1715042E-13 -2.3594437E-13 A13 4.8487810E-15 -2.0591863E-15 A14 6.8436160E-17 3.5573040E-16 A15 -6.3561781E-18 -2.4949242E-18 A16 2.5912812E-20 -2.6393673E—19 A17 3.9402657E-21 4.4735259E-21 A18 -5.0331553E-23 6.6318898E-23 A19 -9.6376125E-25 -1.8494826E-24 A20 1.7328343E-26 7.3938706E-27

[0319] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -1.0260653E-04 4.6312625E-05 A5 -5.0338134E-06 3.0858106E-06 A6 5.5082880E-06 -2.4471839E-08 A7 -7.6033009E-07 1.0210004E-07 A8 -1.1234422E-08 -1.0191542E-08 A9 1.1115237E-08 1.6417956E-09 A10 -7.8390665E-10 9.0967586E-12

[0320] [Example 5]

[0321] The structure of the projection optical system and the cross-sectional view of the light beam of Example 5 are shown in FIG. Figure 13 The projection optical system of Example 5 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive focal power, a 2B lens group G2B having positive focal power, a 2C lens group G2C having negative focal power, and a 2D lens group G2D having positive focal power. During zooming, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the display surface Sim, while the 2B lens group G2B and the 2C lens group G2C change the distance between them and move.

[0322] The first optical system G1 comprises lenses L1a to L1l, in order from magnification to reduction. The 2A lens group G2A comprises lenses L2a to L2d, in order from magnification to reduction. The 2B lens group G2B comprises lens L2e. The 2C lens group G2C comprises lens L2f, an aperture stop St, and lenses L2g to L2i, in order from magnification to reduction. The 2D lens group G2D comprises lens L2j. Lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN. The focusing group comprises lenses L1a to L1i. The back focus correction group comprises lenses L2a to L2c.

[0323] Regarding the projection optical system of Example 5, basic lens data are shown in Tables 17A and 17B, specifications and variable surface spacing during zooming are shown in Table 18, variable surface spacing during focusing is shown in Table 19, aspheric coefficients are shown in Table 20, and various aberration diagrams are shown in Table 21. Figure 14 Each aberration diagram is a diagram obtained when the projection distance is 688.0 mm (millimeter).

[0324] [Table 17A]

[0325] Example 5

[0326] Sn R D Nd ν d ED *1 -18.0693 3.5099 1.51007 56.24 46.6 *2 -63.1966 5.6497 38.9 3 44.7407 1.4784 1.72916 54.68 4 9.1611 6.4442 5 -24.4304 0.7193 1.56883 56.04 6 24.4791 0.1607 7 12.5601 7.9806 1.75500 52.32 14.1 8 -46.6271 2.7921 10.2 9 -9.1401 1.1468 1.80518 25.46 10 -67.4919 0.2028 *11 153.7799 5.9298 1.69350 53.18 *12 -11.9751 0.1593 13 160.6147 5.7221 1.49700 81.61 14 -15.0632 0.1593 15 28.2997 5.4656 1.43700 95.10 16 -25.7093 0.0793 17 -24.9593 0.8001 1.84666 23.78 18 41.9790 9.9304 19 67.3894 5.5489 1.83481 42.74 20 -41.3789 0.1593 21 18.4621 5.0133 1.83481 42.74 22 38.5128 3.2926 23 -89.0488 0.7993 1.56883 56.36 24 32.4373 12.0409

[0327] [Table 17B]

[0328] Example 5

[0329] Sn R D Nd ν d 25 -14.9472 0.7999 1.65844 50.88 26 -930.0538 3.6601 27 -27.9393 5.0701 1.80518 25.46 28 -17.2954 4.1034 29 48.7123 8.9971 1.77250 49.60 30 -55.4501 4.3154 31 31.1599 1.7950 1.51742 52.43 32 20.1289 DD

[32] 33 33.8199 2.4994 1.85883 30.00 34 -524.3139 DD

[34] 35 21.2094 1.3838 1.60342 38.03 36 13.2100 2.3248 37(St) ∞ 4.5182 38 -13.4007 0.7199 1.84666 23.78 39 62.7408 0.0964 40 72.7421 4.2797 1.49700 81.61 41 -16.2665 0.1667 42 78.3912 6.2723 1.49700 81.61 43 -19.4246 DD

[43] 44 66.9950 3.3066 1.89286 20.36 45 -92.2606 12.0000 46 ∞ 26.4000 1.51680 64.20 47 ∞ 0.6573

[0330] [Table 18] Example 5

[0331] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 5.84 6.03 6.43 Bf 30.0 30.0 30.0 FNo. 1.81 1.82 1.85 2ω[°] 119.4 117.8 114.6 DD

[32] 20.84 19.29 16.28 DD

[34] 3.29 3.74 4.84 DD

[43] 16.07 17.19 19.10

[0332] [Table 19]

[0333] Example 5

[0334] Projection distance 688 515.6 3439 The gap between 18 and 19 faces 9.9304 10.0724 9.5845

[0335] [Table 20]

[0336] Example 5

[0337] Sn 1 2 KA -3.3664571E-02 3.1640446E+00 A3 -5.6352061E-04 -1.1174484E-04 A4 8.7985973E-04 6.0651289E-04 A5 -8.9890239E-05 -3.6193407E-05 A6 9.5236200E-07 -4.1036821E-06 A7 4.5831640E-07 5.0327319E-07 A8 -2.8385972E-08 -1.2396621E-09 A9 -5.7165360E-10 -2.0100873E-09 A10 1.1434591E-10 5.9010667E-11 A11 -2.0865623E-12 4.0564013E-12 A12 -1.9673223E-13 -2.0989892E-13 A13 8.2883378E-15 -3.0398125E-15 A14 1.2834418E-16 3.2009653E-16 A15 -1.1975409E-17 -1.3997371E-18 A16 4.8018952E-20 -2.3138308E-19 A17 8.1584804E-21 3.8915599E-21 A18 -1.0819360E-22 4.6446445E-23 A19 -2.1909701E-24 -1.7399115E-24 A20 4.1151682E-26 1.3398597E-26

[0338] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 0.0000000E+00 0.0000000E+00 A4 -1.1251467E-04 3.8542975E-05 A5 -1.0309803E-05 4.8273273E-06 A6 6.8515993E-06 6.0099695E-08 A7 -9.3111160E-07 -6.0187951E-08 A8 -2.3040939E-08 1.9229409E-09 A9 1.5077886E-08 2.5803675E-09 A10 -1.1062772E-09 -2.1582100E-10

[0339] [Example 6]

[0340] The structure of the projection optical system and the cross-sectional view of the light beam of Example 6 are shown in FIG. Figure 15 The projection optical system of Example 6 includes, in order from the magnification side to the reduction side, a first optical system G1 and a second optical system G2. The second optical system G2 includes, in order from the magnification side to the reduction side, a 2A lens group G2A having positive focal power, a 2B lens group G2B having positive focal power, a 2C lens group G2C having negative focal power, and a 2D lens group G2D having positive focal power. When changing magnification, the 2A lens group G2A and the 2D lens group G2D are fixed relative to the display surface Sim, and the 2B lens group G2B and the 2C lens group G2C change the distance between them and move.

[0341] The first optical system G1 comprises lenses L1a to L1l, in order from magnification to reduction. The 2A lens group G2A comprises lenses L2a to L2d, in order from magnification to reduction. The 2B lens group G2B comprises lens L2e. The 2C lens group G2C comprises lens L2f, an aperture stop St, and lenses L2g to L2i, in order from magnification to reduction. The 2D lens group G2D comprises lens L2j. Lens L1d corresponds to the P lens component LP, and lens L1c corresponds to the N lens component LN. The focusing group comprises lenses L1a to L1i. The back focus correction group comprises lenses L2a to L2c.

[0342] Regarding the projection optical system of Example 6, basic lens data are shown in Tables 21A and 21B, specifications and variable surface spacing during zooming are shown in Table 22, variable surface spacing during focusing is shown in Table 23, aspheric coefficients are shown in Table 24, and various aberration diagrams are shown in Table 25. Figure 16 Each aberration diagram is a diagram obtained when the projection distance is 767.9 mm (millimeter).

[0343] [Table 21A] Example 6

[0344] Sn R D Nd ν d ED *1 -19.8413 4.9115 1.53638 56.09 50.40 *2 -37.1157 4.8792 42.2 3 48.4630 0.8921 1.69680 55.53 4 10.3833 6.5963 5 -29.6917 1.2374 1.53172 48.84 6 13.8968 0.1790 7 11.6435 8.3779 1.77250 49.60 14.80 8 -57.1870 2.8441 10.8 9 -9.3683 2.7262 1.80518 25.46 10 -64.1961 0.1778 *11 398.2368 4.9200 1.58313 59.38 *12 -11.3729 0.1778 13 55.3554 6.0007 1.49700 81.61 14 -17.6023 0.1791 15 30.6413 5.8925 1.43700 95.10 16 -25.4077 0.0885 17 -24.6259 0.8921 1.84666 23.78 18 53.9894 9.9672 19 62.2918 5.6254 1.83481 42.74 20 -49.4798 0.1778 21 21.3038 5.5466 1.83481 42.74 22 72.8487 2.6758 23 -72.9490 0.8928 1.56883 56.36 24 31.3676 12.3666

[0345] [Table 21B]

[0346] Example 6

[0347] Sn R D Nd ν d 25 -14.9712 3.5831 1.65844 50.88 26 -354.6401 3.4735 27 -32.1423 6.8878 1.80518 25.46 28 -20.3465 0.1786 29 59.2601 7.8967 1.77250 49.60 30 -55.2274 11.3794 31 34.6065 0.8933 1.51742 52.43 32 23.1253 DD

[32] 33 38.5640 2.8756 1.85883 30.00 34 -247.4082 DD

[34] 35 26.7581 0.9202 1.60342 38.03 36 15.1388 3.0575 37(St) ∞ 4.3753 38 -14.3702 0.8028 1.84666 23.78 39 73.7157 0.1076 40 88.9363 5.1425 1.49700 81.61 41 -17.0864 0.1781 42 90.1976 9.1844 1.49700 81.61 43 -22.2561 DD

[43] 44 72.3664 3.7583 1.89286 20.36 45 -118.2609 14.2857 46 ∞ 31.2500 1.51680 64.20 47 ∞ 0.5540

[0348] [Table 22] Example 6

[0349] WIDE MIDDLE TELE Zr 1.00 1.03 1.10 |f| 6.52 6.73 7.17 Bf 35.4 35.4 35.4 FNo. 1.81 1.82 1.84 2ω[°] 113.6 112.0 108.6 DD

[32] 23.48 21.81 18.59 DD

[34] 2.91 3.43 4.68 DD

[43] 17.14 18.29 20.26

[0350] [Table 23]

[0351] Example 6

[0352] Projection distance 767.9 5754 3839 The gap between 18 and 19 faces 9.9672 10.1191 9.5989

[0353] [Table 24]

[0354] Example 6

[0355] Sn 1 2 KA -2.2155115E-01 9.1384947E-01 A3 -6.8085845E-04 -4.7069615E-04 A4 6.0485741E-04 4.8967050E-04 A5 -5.2622833E-05 -2.6678002E-05 A6 4.4612404E-07 -2.5899908E-06 A7 2.1120462E-07 3.3815845E-07 A8 -1.1524238E-08 -3.9687203E-09 A9 -2.0459223E-10 -1.1513241E-09 A10 3.6527824E-11 4.6191067E-11 A11 -6.0022202E-13 1.8817211E-12 A12 -4.9174314E-14 -1.3624062E-13 A13 1.8553599E-15 -7.9426040E-16 A14 2.4922922E-17 1.9071456E-16 A15 -2.0951898E-18 -1.3632834E-18 A16 7.6516719E-21 -1.3962802E-19 A17 1.1161753E-21 1.9196361E-21 A18 -1.3151802E-23 4.4638214E-23 A19 -2.3441752E-25 -6.8897781E-25 A20 3.9019600E-27 -3.1915522E-27

[0356] Sn 11 12 KA 1.0000000E+00 1.0000000E+00 A3 -5.7261720E-20 6.6477620E-20 A4 -8.0343091E-05 3.3315776E-05 A5 -1.1706655E-05 9.5520850E-07 A6 5.3221192E-06 2.941031SE-07 A7 -5.9171762E-07 -5.5012370E-09 A8 -2.4500854E-08 -4.5901039E-09 A9 9.2842951E-09 1.7356234E-09 A10 -5.5077917E-10 -1.0121243E-10

[0357] Regarding the projection optical systems of Examples 1 to 6, the values of Ymax, Y55, Y50, Y40, and ρL1 are shown in Table 25, and the corresponding values of conditional expressions (1) to (20) are shown in Table 26. The corresponding values of conditional expressions (13), (14), and (17) to (20) are values when the magnification of the projection optical system is 120 times. The projection optical system of the present invention is based on the use of a magnification of 50 times or more (that is, the lateral magnification of the entire projection optical system is 0.02 or less). The corresponding values of the embodiments shown in Table 26 can also be used as the upper limit or lower limit of the conditional expression to set the preferred range of the conditional expression.

[0358] [Table 25]

[0359] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Ymax 10 10 10 10 10 10 Y55 8.83 8.80 8.85 8.82 8.34 9.34 Y50 7.36 7.33 7.38 7.35 6.96 7.78 Y40 5.16 5.15 5.18 5.17 4.90 5.46 ρL1 1.03 1.03 1.03 1.03 1.01 1.03

[0360] [Table 26]

[0361]

[0362] The projection optical systems of Examples 1 to 6 have a full viewing angle of 110 degrees or more at the wide-angle end, and have a wide viewing angle. They also have a small F-number of less than 2. Furthermore, the projection optical systems of Examples 1 to 6 have a long back focus and a compact design, while achieving high optical performance through excellent correction of various aberrations.

[0363] Next, a projection display device according to an embodiment of the present invention will be described. Figure 17 It is a schematic structural diagram of a projection display device according to one embodiment of the present invention. Figure 17 The projection display device 100 shown has: a projection optical system 10 according to an embodiment of the present invention; a light source 15; and transmissive display elements 11a to 11c as light valves corresponding to light of various colors and outputting optical images. Furthermore, the projection display device 100 has dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, condensing lenses 16a to 16c, and total reflection mirrors 18a to 18c for deflecting the light path. Figure 17 In FIG. 1 , a projection optical system 10 is schematically shown. In addition, an integrator is arranged between the light source 15 and the dichroic mirror 12. Figure 17 The illustration is omitted.

[0364] White light from a light source 15 is separated into three color light beams (green light, blue light, and red light) by dichroic mirrors 12 and 13. The light then passes through condenser lenses 16a to 16c and is incident on transmissive display elements 11a to 11c corresponding to the respective color light beams, where it is modulated. The light is then color-synthesized by a cross dichroic prism 14 before being incident on a projection optical system 10. The projection optical system 10 projects an optical image based on the modulated light modulated by the transmissive display elements 11a to 11c onto a screen 105.

[0365] Figure 18 It is a schematic structural diagram of a projection display device according to another embodiment of the present invention. Figure 18 The projection display device 200 shown has: a projection optical system 210 according to an embodiment of the present invention; a light source 215; and DMD (Digital Micromirror Device: registered trademark) elements 21a to 21c as light valves corresponding to light of various colors and outputting optical images. In addition, the projection display device 200 has TIR (Total Internal Reflection) prisms 24a to 24c for color separation and color synthesis, and a polarization beam splitter prism 25 for separating illumination light and projection light. In addition, Figure 18 The projection optical system 210 is schematically shown in FIG. 1 . An integrator is provided between the light source 215 and the polarization beam splitting prism 25. Figure 18 The illustration is omitted.

[0366] White light from light source 215 is reflected by the reflective surface inside polarization beam splitter prism 25 and then split into three color beams (green, blue, and red) by TIR prisms 24a-24c. Each of the split color beams is incident on the corresponding DMD elements 21a-21c for modulation. After passing through TIR prisms 24a-24c again for color synthesis, the light is transmitted through polarization beam splitter prism 25 and is incident on projection optical system 210. Projection optical system 210 projects an optical image based on the modulated light by DMD elements 21a-21c onto screen 205.

[0367] Figure 19 It is a schematic structural diagram of a projection display device according to still another embodiment of the present invention. Figure 19 The projection display device 600 shown in FIG. 1 includes: a projection optical system 66 according to an embodiment of the present invention; a light source 61; and a DMD element 64 as a light valve that outputs an optical image corresponding to each color of light. Furthermore, the projection display device 600 includes a color wheel 62, a light guide optical system 63, and a TIR prism 65. Figure 19 , the projection optical system 66 is schematically shown.

[0368] Color wheel 62 is circumferentially equipped with filters for three colors: green, blue, and red. As color wheel 62 rotates, filters of each color are sequentially embedded in the optical path. White light from light source 61 is incident on the rotating color wheel 62 and time-divided into three color beams (green, blue, and red). After time-divided separation, the time-divided color beams pass through light guide system 63 and TIR prism 65 before being modulated by DMD element 64. They then pass through TIR prism 65 again and enter projection optical system 66. Projection optical system 66 projects an optical image based on the modulated light from DMD element 64 onto screen 67.

[0369] While the present invention has been described above using embodiments and examples, the present invention is not limited to these embodiments and examples and is capable of various modifications. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspheric coefficient of each lens are not limited to the values shown in the above embodiments and may employ other values.

[0370] Furthermore, the projection display device involved in the technology of the present invention is not limited to the above-mentioned structure. For example, the optical components and light valves used for light beam separation or light beam synthesis can be modified in various ways. The light valve is not limited to a method of spatially modulating the light from the light source by an image display element and outputting it as an optical image based on image data. It can also be a method of outputting the light output from a self-luminous image display element itself as an optical image based on image data. As a self-luminous image display element, for example, an image display element composed of a two-dimensional array of light-emitting elements such as LEDs (Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes) can be cited. The light valve is not limited to a three-plate method, but can be a single-plate method. By configuring the light valve to correspond to the single-plate method, the optical engine can be miniaturized.

[0371] Regarding the above-mentioned embodiments and examples, the following supplementary notes are further disclosed.

[0372] [Note 1]

[0373] A projection optical system projects an image on a reduction-side imaging surface onto an enlargement-side imaging surface, wherein:

[0374] The half viewing angle on the magnified side is more than 50 degrees.

[0375] When one lens component is a single lens or a cemented lens, the projection optical system includes:

[0376] The projection optical system includes a lens component having positive refractive power, namely, a P lens component, which is closest to the magnification side, and a lens component having negative refractive power, namely, an N lens component, which is arranged adjacent to the magnification side of the P lens component.

[0377] The maximum image height on the reduced side imaging surface is set to Ymax,

[0378] The distance on the optical axis from the surface of the optical element having optical power closest to the magnification side of the projection optical system to the lens surface of the P lens component closest to the magnification side is defined as Zp.

[0379] The curvature radius of the lens surface closest to the magnification side of the P lens component is set to Rpf.

[0380] The curvature radius of the lens surface closest to the reduction side of the N lens component is denoted as Rnr.

[0381] The back focus of the projection optical system at the reduced distance in air conversion is defined as Bf.

[0382] The image height of the light with a half viewing angle of 40 degrees on the magnification side on the imaging surface on the reduction side is set to Y40,

[0383] The image height of the light with a half viewing angle of 50 degrees on the magnification side on the imaging surface on the reduction side is set to Y50.

[0384] When the projection optical system is a variable magnification optical system and Ymax, Zp, Bf, Y40, and Y50 are set to the values at the wide-angle end,

[0385] The projection optical system satisfies the following conditional equations (1), (2), (3), (4), and (5):

[0386] 1<Zp / Ymax<4 (1)

[0387] 0.2<Rpf / Ymax<2.3 (2)

[0388] 0.2<Rnr / Ymax<5 (3)

[0389] 2<Bf / Ymax<8 (4)

[0390] 1.35<Y50 / Y40<1.5 (5).

[0391] [Note 2]

[0392] The projection optical system according to Supplementary Note 1 includes a first optical system and a second optical system in order from the magnification side to the reduction side along the optical path,

[0393] The second optical system forms an intermediate image between the first and second optical systems and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image on the magnification-side imaging plane.

[0394] [Note 3]

[0395] The projection optical system according to Supplementary Note 1 or 2, wherein:

[0396] When the distance between the N lens component and the P lens component on the optical axis is Dnp, and

[0397] When the projection optical system is a variable magnification optical system and Dnp is set to the value at the wide-angle end,

[0398] The projection optical system satisfies the conditional formula (6) represented by the following formula:

[0399] 0<Dnp / Ymax<0.1 (6).

[0400] [Note 4]

[0401] The projection optical system according to any one of Supplementary Notes 1 to 3, wherein:

[0402] When the curvature radius of the lens surface closest to the reduction side of the P lens component is Rpr,

[0403] The projection optical system satisfies the conditional equation (7) represented by the following equation:

[0404] 0<(Rpr+Rpf) / (Rpr-Rpf)<2 (7).

[0405] [Note 5]

[0406] The projection optical system according to any one of Supplementary Notes 1 to 4, wherein:

[0407] When the larger of the maximum effective diameter of the lens surface of the P lens component closest to the magnification side and the maximum effective diameter of the lens surface of the P lens component closest to the reduction side is defined as EDp,

[0408] The projection optical system satisfies the conditional formula (8) represented by the following formula:

[0409] 0.5<EDp / Ymax<2.5 (8).

[0410] [Note 6]

[0411] The projection optical system according to any one of Supplementary Notes 1 to 5, wherein:

[0412] When the curvature radius of the lens surface closest to the magnification side of the N lens component is set to Rnf,

[0413] The projection optical system satisfies the conditional formula (9) represented by the following formula:

[0414] -1<(Rnr+Rnf) / (Rnr-Rnf)<0.5 (9).

[0415] [Note 7]

[0416] The projection optical system according to Supplementary Note 2, wherein:

[0417] The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0418] A group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, a maximum air gap between lens surfaces on the optical axis in the magnification side fixed group is set as dAmax, and

[0419] When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end,

[0420] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0421] 0.2<dAmax / Ymax<2.5(10).

[0422] [Note 8]

[0423] The projection optical system according to Supplement 2 or 7, wherein:

[0424] The projection optical system is a zoom lens.

[0425] In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group,

[0426] The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group.

[0427] During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

[0428] [Note 9]

[0429] The projection optical system according to Supplementary Note 8, wherein:

[0430] When the focal length of the 2B lens group is set to f2B, and

[0431] When the focal length of the 2C lens group is set to f2C,

[0432] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0433] 0<f2B / |f2C|<0.5 (11).

[0434] [Note 10]

[0435] The projection optical system according to any one of Supplementary Notes 1 to 9, wherein:

[0436] The larger of the maximum effective diameter of the magnification side surface of the lens closest to the magnification side of the projection optical system and the maximum effective diameter of the reduction side surface of the lens closest to the magnification side of the projection optical system is defined as EDL1, and

[0437] When the specific gravity of the lens closest to the magnification side of the projection optical system is ρL1,

[0438] The projection optical system satisfies the conditional formula (12) represented by the following formula:

[0439] 0.5<EDL1×ρL1 / Ymax<10 (12).

[0440] [Note 11]

[0441] The projection optical system according to any one of Supplementary Notes 1 to 10, wherein:

[0442] The P lens component is a single lens,

[0443] The refractive index of the P lens component with respect to the d-line is 1.65 or greater.

[0444] [Note 12]

[0445] The projection optical system according to Supplementary Note 11, wherein:

[0446] The N lens component is a single lens,

[0447] The refractive index of the N lens component with respect to the d-line is 1.65 or less.

[0448] [Note 13]

[0449] The projection optical system according to Supplementary Note 2, wherein:

[0450] The first optical system includes an aspherical lens.

[0451] [Note 14]

[0452] The projection optical system according to Supplementary Note 13, wherein:

[0453] The first optical system includes two aspherical lenses.

[0454] [Note 15]

[0455] The projection optical system according to Supplementary Note 13 or 14, wherein:

[0456] The lens surface closest to the magnification side of the first optical system is an aspherical surface that is concave toward the magnification side in a paraxial region and has an inflection point where the concavo-convex shape changes midway as moving from the optical axis toward the periphery.

[0457] [Note 16]

[0458] The projection optical system according to any one of Supplementary Notes 1 to 15, wherein:

[0459] The reduced side is telecentric.

[0460] [Note 17]

[0461] A projection display device includes the projection optical system according to any one of Supplementary Notes 1 to 16.

[0462] [Note 18]

[0463] A projection optical system includes a first optical system and a second optical system in sequence along an optical path from a magnification side to a reduction side, wherein:

[0464] The second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image onto the magnification-side imaging plane.

[0465] A focusing group is arranged on the magnification side of the projection optical system. The focusing group includes six or more lenses and adjusts the focus of the entire image plane when the projection distance changes by moving along the optical axis.

[0466] During the focus adjustment, the intervals between all lenses in the focus group remain unchanged.

[0467] [Note 19]

[0468] The projection optical system according to Supplementary Note 18, wherein:

[0469] The focusing group is arranged in the first optical system.

[0470] [Note 20]

[0471] The projection optical system according to Supplementary Note 18 or 19, wherein:

[0472] When the paraxial lateral magnification of the focus group is set to βF,

[0473] The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFr, and

[0474] When the projection optical system is a variable magnification optical system and βF and βFr are set to the values at the wide-angle end,

[0475] The projection optical system satisfies the conditional formula (13) represented by the following formula:

[0476] 0.02<(1-βF 2 )×βFr 2 <0.2 (13).

[0477] [Note 21]

[0478] The projection optical system according to any one of Supplementary Notes 18 to 20, wherein:

[0479] When the paraxial lateral magnification of the focus group is set to βF,

[0480] The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFr, and the maximum image height on the reduction side imaging plane is Ymax.

[0481] The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the focus group moves 0.1×Ymax along the optical axis is defined as ΔtF, and

[0482] When the projection optical system is a variable magnification optical system and βF, βFr, Ymax, and ΔtF are set to the values at the wide-angle end,

[0483] The projection optical system satisfies the conditional equation (14) represented by the following equation:

[0484] 0.1<((1-βF 2 )×βFr 2 ) / ΔtF<0.5 (14).

[0485] [Note 22]

[0486] The projection optical system according to any one of Supplementary Notes 18 to 21, wherein:

[0487] The focusing group includes two or more positive lenses.

[0488] [Note 23]

[0489] The projection optical system according to any one of Supplementary Notes 18 to 22, wherein:

[0490] The lens surface of the focusing group closest to the magnification side is an aspherical surface that is concave toward the magnification side in a paraxial region and has an inflection point where the concavo-convex shape changes midway as moving from the optical axis toward the periphery.

[0491] [Note 24]

[0492] The projection optical system according to any one of Supplementary Notes 18 to 23, wherein:

[0493] One of the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is a positive lens, and the other is a negative lens,

[0494] The interval on the optical axis between the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is dFr12,

[0495] The maximum image height on the reduced side imaging surface is set to Ymax, and

[0496] When the projection optical system is a variable magnification optical system and Ymax is set to the value at the wide-angle end,

[0497] The projection optical system satisfies the conditional equation (15) represented by the following equation:

[0498] 0≤dFr12 / Ymax<0.1 (15).

[0499] [Note 25]

[0500] The projection optical system according to any one of Supplementary Notes 18 to 24, further comprising a back focus correction group that adjusts the back focus by moving along the optical axis.

[0501] [Note 26]

[0502] The projection optical system according to any one of Supplementary Notes 18 to 25, wherein:

[0503] The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0504] A group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, a maximum air gap between lens surfaces on the optical axis in the magnification side fixed group is set as dAmax, and

[0505] When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end,

[0506] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0507] 0.2<dAmax / Ymax<2.5 (10).

[0508] [Note 27]

[0509] The projection optical system according to any one of Supplementary Notes 18 to 26, wherein:

[0510] The projection optical system is a zoom lens.

[0511] In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group,

[0512] The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group.

[0513] During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

[0514] [Note 28]

[0515] The projection optical system according to Supplementary Note 27, wherein:

[0516] When the focal length of the 2B lens group is set to f2B, and

[0517] When the focal length of the 2C lens group is set to f2C,

[0518] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0519] 0<f2B / |f2C|<0.5 (11).

[0520] [Note 29]

[0521] A projection display device comprising the projection optical system according to any one of Supplementary Notes 18 to 28.

[0522] [Note 30]

[0523] A projection optical system includes a first optical system and a second optical system in sequence along an optical path from a magnification side to a reduction side, wherein:

[0524] The second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image onto the magnification-side imaging plane.

[0525] A focusing group and a back focus correction group are arranged in the projection optical system. The focusing group adjusts the focus of the entire image plane when the projection distance changes by moving along the optical axis. The back focus correction group adjusts the back focus by moving along the optical axis.

[0526] The distance on the optical axis from the lens surface closest to the magnification side of the first optical system to the lens surface closest to the reduction side among the lens surfaces included in the focusing group and the back focus correction group is ZFBr,

[0527] The focal length of the projection optical system is f, and

[0528] When the projection optical system is a variable magnification optical system and ZFBr and f are set to the values at the wide-angle end,

[0529] The projection optical system satisfies the conditional equation (16) represented by the following equation:

[0530] 5<ZFBr / |f|<20 (16).

[0531] [Note 31]

[0532] The projection optical system according to Supplementary Note 30, wherein:

[0533] When the paraxial lateral magnification of the focus group is set to βFF,

[0534] The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr,

[0535] The paraxial lateral magnification of the back focus correction group is set to βB,

[0536] The composite paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr, and

[0537] When the projection optical system is a variable magnification optical system and βFF, βFFr, βB, and βBr are set to the values at the wide-angle end,

[0538] The projection optical system satisfies the following conditional equations (17) and (18):

[0539] 0.02<(1-βFF 2 )×βFFr 2 <0.2(17)

[0540] 0.1<|(1-βB 2 )×βBr 2 |<2 (18).

[0541] [Note 32]

[0542] The projection optical system according to Supplementary Note 30 or 31, wherein:

[0543] When the paraxial lateral magnification of the back focus correction group is set to βB,

[0544] The composite paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr,

[0545] The maximum image height on the reduced side imaging surface is set to Ymax,

[0546] The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the back focus correction group moves 0.1×Ymax along the optical axis is set as ΔtB, and

[0547] When the projection optical system is a variable magnification optical system and βB, βBr, Ymax, and ΔtB are set to the values at the wide-angle end,

[0548] The projection optical system satisfies the conditional formula (19) represented by the following formula:

[0549] 0.7<|(1-βB 2 )×βBr 2 | / ΔtB<1.4 (19).

[0550] [Note 33]

[0551] The projection optical system according to any one of Supplementary Notes 30 to 32, wherein:

[0552] When the paraxial lateral magnification of the focus group is set to βFF,

[0553] The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr,

[0554] The maximum image height on the reduced side imaging surface is set to Ymax,

[0555] The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the focus group moves 0.1×Ymax along the optical axis is defined as ΔtFF, and

[0556] When the projection optical system is a variable magnification optical system and βFF, βFFr, Ymax, and ΔtFF are set to values at the wide-angle end,

[0557] The projection optical system satisfies the conditional equation (20) represented by the following equation:

[0558] 0.1<((1-βFF 2 )×βFFr 2 ) / ΔtFF<0.5 (20).

[0559] [Note 34]

[0560] The projection optical system according to any one of Supplementary Notes 30 to 33, wherein:

[0561] The focusing group and the back focus correction group are capable of moving independently of each other.

[0562] [Note 35]

[0563] The projection optical system according to any one of Supplementary Notes 30 to 34, wherein:

[0564] The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system.

[0565] A group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, a maximum air gap between lens surfaces on the optical axis in the magnification side fixed group is set as dAmax, and

[0566] When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end,

[0567] The projection optical system satisfies the conditional formula (10) represented by the following formula:

[0568] 0.2<dAmax / Ymax<2.5 (10).

[0569] [Note 36]

[0570] The projection optical system according to any one of Supplementary Notes 30 to 35, wherein:

[0571] The projection optical system is a zoom lens.

[0572] In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group,

[0573] The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group.

[0574] During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

[0575] [Note 37]

[0576] The projection optical system according to Supplementary Note 36, wherein:

[0577] When the focal length of the 2B lens group is set to f2B, and

[0578] When the focal length of the 2C lens group is set to f2C,

[0579] The projection optical system satisfies the conditional formula (11) represented by the following formula:

[0580] 0<f2B / |f2C|<0.5 (11).

[0581] [Note 38]

[0582] A projection display device comprising the projection optical system according to any one of Supplementary Notes 30 to 37.

Claims

1. A projection optical system that projects an image on a reduction-side imaging surface onto an enlargement-side imaging surface, wherein: The half viewing angle on the magnified side is more than 50 degrees. When one lens component is a single lens or a cemented lens, the projection optical system includes: The projection optical system includes a lens component having positive refractive power, namely, a P lens component, which is closest to the magnification side, and a lens component having negative refractive power, namely, an N lens component, which is arranged adjacent to the magnification side of the P lens component. The maximum image height on the reduced side imaging surface is set to Ymax, The distance on the optical axis from the surface of the optical element having optical power closest to the magnification side of the projection optical system to the lens surface of the P lens component closest to the magnification side is Zp, The curvature radius of the lens surface closest to the magnification side of the P lens component is Rpf, The curvature radius of the lens surface closest to the reduction side of the N lens component is Rnr, The back focus of the projection optical system on the reduction side in the air conversion distance is Bf, The image height of the light with a half viewing angle of 40 degrees on the magnification side on the imaging surface of the reduction side is set to Y40, The image height of the light with a half viewing angle of 50 degrees on the magnification side on the imaging surface of the reduction side is set to Y50, and When the projection optical system is a variable magnification optical system and Ymax, Zp, Bf, Y40, and Y50 are set to the values at the wide-angle end, The projection optical system satisfies the following conditional equations (1), (2), (3), (4), and (5): 1<Zp / Ymax<4 (1) 0.2<Rpf / Ymax<2.3 (2) 0.2<Rnr / Ymax<5 (3) 2<Bf / Ymax<8 (4) 1.35<Y50 / Y40<1.5 (5).

2. The projection optical system according to claim 1, comprising a first optical system and a second optical system in order from the magnification side to the reduction side along the optical path. The second optical system forms an intermediate image between the first and second optical systems and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image on the magnification-side imaging plane.

3. The projection optical system according to claim 1 or 2, wherein: When the distance between the N lens component and the P lens component on the optical axis is Dnp, and When the projection optical system is a variable magnification optical system and Dnp is set to the value at the wide-angle end, The projection optical system satisfies the conditional formula (6) represented by the following formula: 0<Dnp / Ymax<0.1 (6).

4. The projection optical system according to claim 1 or 2, wherein: When the curvature radius of the lens surface closest to the reduction side of the P lens component is Rpr, The projection optical system satisfies the conditional equation (7) represented by the following equation: 0<(Rpr+Rpf) / (Rpr-Rpf)<2 (7).

5. The projection optical system according to claim 1 or 2, wherein: When the larger of the maximum effective diameter of the lens surface of the P lens component closest to the magnification side and the maximum effective diameter of the lens surface of the P lens component closest to the reduction side is defined as EDp, The projection optical system satisfies the conditional formula (8) represented by the following formula: 0.5<EDp / Ymax<2.5 (8).

6. The projection optical system according to claim 1 or 2, wherein: When the curvature radius of the lens surface closest to the magnification side of the N lens component is set to Rnf, The projection optical system satisfies the conditional formula (9) represented by the following formula: -1<(Rnr+Rnf) / (Rnr-Rnf)<0.5 (9).

7. The projection optical system according to claim 2, wherein: The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system. When a group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, The longest air gap between the lens surfaces on the optical axis in the magnification side fixed group is set to dAmax, and When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end, The projection optical system satisfies the conditional formula (10) represented by the following formula: 0.2<dAmax / Ymax<2.5 (10).

8. The projection optical system according to claim 2, wherein: The projection optical system is a zoom lens. In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group, The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group. During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

9. The projection optical system according to claim 8, wherein: When the focal length of the 2B lens group is set to f2B, and When the focal length of the 2C lens group is set to f2C, the projection optical system satisfies the conditional expression (11) represented by the following expression: 0<f2B / |f2C|<0.5 (11).

10. The projection optical system according to claim 1 or 2, wherein: The larger of the maximum effective diameter of the magnification side surface of the lens closest to the magnification side of the projection optical system and the maximum effective diameter of the reduction side surface of the lens closest to the magnification side of the projection optical system is defined as EDL1, and When the specific gravity of the lens closest to the magnification side of the projection optical system is ρL1, The projection optical system satisfies the conditional formula (12) represented by the following formula: 0.5<EDL1×ρL1 / Ymax<10 (12).

11. The projection optical system according to claim 1 or 2, wherein: The P lens component is a single lens, The refractive index of the P lens component with respect to the d-line is 1.65 or greater.

12. The projection optical system according to claim 11, wherein: The N lens component is a single lens, The refractive index of the N lens component with respect to the d-line is 1.65 or less.

13. The projection optical system according to claim 2, wherein: The first optical system includes an aspherical lens.

14. The projection optical system according to claim 13, wherein: The first optical system includes two aspherical lenses.

15. The projection optical system according to claim 13, wherein: The lens surface closest to the magnification side of the first optical system is an aspherical surface that is concave toward the magnification side in a paraxial region and has an inflection point where the concavo-convex shape changes midway as moving from the optical axis toward the periphery.

16. The projection optical system according to claim 2, wherein: The reduced side is telecentric. 17 . A projection display device comprising the projection optical system according to claim 1 .

18. A projection optical system comprising a first optical system and a second optical system in order from the magnification side to the reduction side along the optical path, wherein: The second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image onto the magnification-side imaging plane. A focusing group is arranged on the magnification side of the projection optical system. The focusing group includes six or more lenses and adjusts the focus of the entire image plane when the projection distance changes by moving along the optical axis. During the focus adjustment, the intervals between all lenses in the focus group remain unchanged.

19. The projection optical system according to claim 18, wherein: The focusing group is arranged in the first optical system.

20. The projection optical system according to claim 18 or 19, wherein: When the paraxial lateral magnification of the focus group is set to βF, The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFr, and When the projection optical system is a variable magnification optical system and βF and βFr are set to the values at the wide-angle end, The projection optical system satisfies the conditional formula (13) represented by the following formula: 0.02<(1-βF 2 )×βFr 2 <0.2 (13).

21. The projection optical system according to claim 18 or 19, wherein: When the paraxial lateral magnification of the focus group is set to βF, The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFr, The maximum image height on the reduced side imaging surface is set to Ymax, The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the focus group moves 0.1×Ymax along the optical axis is defined as ΔtF, and When the projection optical system is a variable magnification optical system and βF, βFr, Ymax, and ΔtF are set to the values at the wide-angle end, The projection optical system satisfies the conditional equation (14) represented by the following equation: 0.1<((1-βF 2 )×βFr 2 ) / ΔtF<0.5 (14).

22. The projection optical system according to claim 18 or 19, wherein: The focusing group includes two or more positive lenses.

23. The projection optical system according to claim 18 or 19, wherein: The lens surface of the focusing group closest to the magnification side is an aspherical surface that is concave toward the magnification side in a paraxial region and has an inflection point where the concavo-convex shape changes midway as moving from the optical axis toward the periphery.

24. The projection optical system according to claim 18 or 19, wherein: One of the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is a positive lens, and the other is a negative lens, The interval on the optical axis between the first lens from the reduction side of the focus group and the second lens from the reduction side of the focus group is dFr12, The maximum image height on the reduced side imaging surface is set to Ymax, and When the projection optical system is a variable magnification optical system and Ymax is set to the value at the wide-angle end, The projection optical system satisfies the conditional equation (15) represented by the following equation: 0≤dFr12 / Ymax<0.1 (15). 25 . The projection optical system according to claim 18 , further comprising a back focus correction group for adjusting the back focus by moving along the optical axis.

26. The projection optical system according to claim 18 or 19, wherein: The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system. When a group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, The longest air gap between the lens surfaces on the optical axis in the magnification side fixed group is set to dAmax, and When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end, The projection optical system satisfies the conditional formula (10) represented by the following formula: 0.2<dAmax / Ymax<2.5 (10).

27. The projection optical system according to claim 18 or 19, wherein: The projection optical system is a zoom lens. In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group, The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group. During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

28. The projection optical system according to claim 27, wherein: When the focal length of the 2B lens group is set to f2B, and When the focal length of the 2C lens group is set to f2C, The projection optical system satisfies the conditional formula (11) represented by the following formula: 0<f2B / |f2C|<0.5 (11). 29 . A projection display device comprising the projection optical system according to claim 18 .

30. A projection optical system comprising a first optical system and a second optical system in order from the magnification side to the reduction side along the optical path, wherein: The second optical system forms an intermediate image between the first optical system and the second optical system and at a position conjugate with the reduction-side imaging plane, and the first optical system re-images the intermediate image onto the magnification-side imaging plane. A focusing group and a back focus correction group are arranged in the projection optical system. The focusing group adjusts the focus of the entire image plane when the projection distance changes by moving along the optical axis. The back focus correction group adjusts the back focus by moving along the optical axis. The distance on the optical axis from the lens surface closest to the magnification side of the first optical system to the lens surface closest to the reduction side among the lens surfaces included in the focusing group and the back focus correction group is ZFBr, The focal length of the projection optical system is f, and When the projection optical system is a variable magnification optical system and ZFBr and f are set to the values at the wide-angle end, The projection optical system satisfies the conditional equation (16) represented by the following equation: 5<ZFBr / |f|<20 (16).

31. The projection optical system according to claim 30, wherein: When the paraxial lateral magnification of the focus group is set to βFF, The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr, The paraxial lateral magnification of the back focus correction group is set to βB, The composite paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr, and When the projection optical system is a variable magnification optical system and βFF, βFFr, βB, and βBr are set to the values at the wide-angle end, The projection optical system satisfies the following conditional equations (17) and (18): 0.02<(1-βFF 2 )×βFFr 2 <0.2 (17) 0.1<|(1-βB 2 )×βBr 2 |<2 (18)。 32. The projection optical system according to claim 30 or 31, wherein: When the paraxial lateral magnification of the back focus correction group is set to βB, The composite paraxial lateral magnification of all lenses closer to the reduction side than the back focus correction group is βBr, The maximum image height on the reduced side imaging surface is set to Ymax, The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the back focus correction group moves 0.1×Ymax along the optical axis is set as ΔtB, and When the projection optical system is a variable magnification optical system and βB, βBr, Ymax, and ΔtB are set to the values at the wide-angle end, The projection optical system satisfies the conditional formula (19) represented by the following formula: 0.7<|(1-βB 2 )×βBr 2 | / ΔtB<1.4 (19)。 33. The projection optical system according to claim 30, wherein: When the paraxial lateral magnification of the focus group is set to βFF, The composite paraxial lateral magnification of all lenses closer to the reduction side than the focusing group is βFFr, The maximum image height on the reduced side imaging surface is set to Ymax, The change in the tangential image plane along the optical axis at a half viewing angle of 50 degrees when the focus group moves 0.1×Ymax along the optical axis is defined as ΔtFF, and When the projection optical system is a variable magnification optical system and βFF, βFFr, Ymax, and ΔtFF are set to values at the wide-angle end, The projection optical system satisfies the conditional equation (20) represented by the following equation: 0.1<((1-βFF 2 )×βFFr 2 ) / ΔtFF<0.5 (20)。 34. The projection optical system according to claim 30 or 31, wherein: The focusing group and the back focus correction group are capable of moving independently of each other.

35. The projection optical system according to claim 30 or 31, wherein: The projection optical system is a zoom lens, and the zoom lens includes a moving lens group that moves when changing magnification in the second optical system. When a group including all lenses closer to the magnification side than the movable lens group closest to the magnification side in the movable lens group included in the projection optical system is set as a magnification side fixed group, The longest air gap between the lens surfaces on the optical axis in the magnification side fixed group is set to dAmax, and When the projection optical system is a variable magnification optical system and dAmax is set to the value at the wide-angle end, The projection optical system satisfies the conditional formula (10) represented by the following formula: 0.2<dAmax / Ymax<2.5 (10).

36. The projection optical system according to claim 30 or 31, wherein: The projection optical system is a zoom lens. In the second optical system, when the interval between the lens group and the adjacent lens group in the optical axis direction changes during zooming is set as one lens group, The second optical system includes, in order from the magnification side to the reduction side along the optical path, a 2A lens group, a 2B lens group, a 2C lens group, and a 2D lens group. During zooming, the 2A lens group and the 2D lens group are fixed relative to the reduction-side imaging plane, and the 2B lens group and the 2C lens group move while changing the intervals between them.

37. The projection optical system according to claim 36, wherein: When the focal length of the 2B lens group is set to f2B, and When the focal length of the 2C lens group is set to f2C, The projection optical system satisfies the conditional formula (11) represented by the following formula: 0<f2B / |f2C|<0.5 (11). 38 . A projection display device comprising the projection optical system according to claim 30 .

Images