Imaging optical system, projection display device, and imaging device

Abstract

To provide an image forming optical system which has various adjustment mechanisms and holds high optical performance in which various aberrations accompanying a wide angle are satisfactorily corrected, a projection type display device equipped with the image forming optical system, and an imaging device equipped with the image forming optical system.SOLUTION: Disclosed is an image forming optical system capable of forming an image on a reduction-side conjugate plane as an intermediate image and re-forming the intermediate image on an enlargement-side conjugate plane as an enlarged image, in which the optical element arranged closest to the magnification side is lens, and includes: a first adjustment group which moves along the optical axis when adjusting an imaging position of a region including the farthest point from the optical axis in the magnified image; and a second adjustment group which moves along the optical axis when adjusting the imaging position of the region including the nearest point from the optical axis in the magnified image. The second adjustment group has a positive refractive power as a whole, and is arranged closest to the reduction side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed herein relates to an imaging optical system, a projection display device, and an imaging device. [Background technology]

[0002] Patent Document 1 below describes an imaging optical system applicable to projection-type display devices. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-133120 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] There is a need for an imaging optical system that is wide-angle and maintains high optical performance with well-corrected aberrations. Furthermore, there is a need for an imaging optical system that allows for various adjustments, such as adjustment of field curvature and adjustment of the image formation position.

[0005] This disclosure has been made in view of the above circumstances and aims to provide an imaging optical system having various adjustment mechanisms and maintaining high optical performance with good correction of aberrations associated with wide-angle lenses, a projection display device equipped with this imaging optical system, and an imaging device equipped with this imaging optical system. [Means for solving the problem]

[0006] A first aspect of the present disclosure is an imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image and re-imaging the intermediate image as an enlarged image on an enlargement conjugate plane, wherein the optical element positioned furthest from the enlargement side is a lens, and the system comprises a first adjustment group that moves along the optical axis when adjusting the imaging position of a region of the enlarged image that includes the farthest point from the optical axis, and a second adjustment group that moves along the optical axis when adjusting the imaging position of a region of the enlarged image that includes the nearest point from the optical axis, wherein the second adjustment group includes at least two lenses and has a positive refractive power as a whole, and is positioned furthest from the enlargement side.

[0007] In the first embodiment, the second adjustment group consists of two lenses, preferably at least one of the two lenses being a positive lens, and when the Abbe number of this positive lens with respect to the d line is νp, the imaging optical system is: νp<45 (1) It is preferable that the condition (1) expressed by is satisfied.

[0008] A second aspect of this disclosure is an imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image and re-imaging the intermediate image as an enlarged image on an enlargement conjugate plane, wherein the optical element positioned furthest from the enlargement side is a lens, and the system comprises a first adjustment group that moves along the optical axis when adjusting the imaging position of a region of the enlarged image that includes the farthest point from the optical axis, and a second adjustment group that moves along the optical axis when adjusting the imaging position of a region of the enlarged image that includes the nearest point from the optical axis, wherein the second adjustment group includes at least one positive lens and has a positive refractive power as a whole, is positioned furthest from the reducing side, and when the Abbe number of the positive lens of the second adjustment group with respect to the d line is νp, νp<45 (1) This is an imaging optical system that satisfies the condition (1) represented by . Hereinafter, in this section, the first and second embodiments will be collectively referred to as the above embodiments.

[0009] In the above aspect, when the focal length of the first adjustment group is f1 and the first adjustment group is composed of a plurality of groups that move by changing the distance between adjacent groups during adjustment, the combined focal length of the plurality of groups of the first adjustment group is f1. When the focal length of the second adjustment group is f2 and the second adjustment group is composed of a plurality of groups that move by changing the distance between adjacent groups during adjustment, the combined focal length of the plurality of groups of the second adjustment group is f2, the imaging optical system satisfies 0.5 < |f1 / f2| < 30 (2) the conditional expression (2) represented by is preferably satisfied.

[0010] In the above aspect, when the paraxial lateral magnification of the first adjustment group is β1 and the first adjustment group is composed of a plurality of groups that move by changing the distance between adjacent groups during adjustment, the combined paraxial lateral magnification of the plurality of groups of the first adjustment group is β1. When the combined paraxial lateral magnification of all the optical systems on the reduction side from the first adjustment group is β1r, the paraxial lateral magnification of the second adjustment group is β2, and the second adjustment group is composed of a plurality of groups that move by changing the distance between adjacent groups during adjustment, the combined paraxial lateral magnification of the plurality of groups of the second adjustment group is β2, the imaging optical system satisfies 0 < |{(1 - β1 2 ) × β1r 2} / (1 - β2 2 )| < 0.5 (3) the conditional expression (3) represented by is preferably satisfied.

[0011] In the above aspect, it is preferable that the first adjustment group is arranged on the magnification side from the intermediate image.

[0012] In the above aspect, when the imaging optical system is composed of a first optical system and a second optical system in order from the magnification side to the reduction side across the intermediate image, the focal length of the first optical system is fU1, the focal length of the imaging optical system is fw, and when fU1 and fw are the values at the wide-angle end when the imaging optical system is a variable magnification optical system, the imaging optical system satisfies 1 < fU1 / |fw| < 5 (4) the conditional expression (4) represented by is preferably satisfied.

[0013] In the above aspect, when the back focus at the air equivalent distance of the imaging optical system is Bfw, the focal length of the imaging optical system is fw, and for Bfw and fw, when the imaging optical system is a zoom optical system, the values at the wide-angle end are used, the imaging optical system satisfies: 3.5 < Bfw / |fw| (5) It is preferable to satisfy the conditional expression (5) represented by the above.

[0014] In the above aspect, it is preferable that the imaging optical system continuously includes, in order from the most magnified side to the reduced side, three single lenses having negative refractive powers.

[0015] In the above aspect, the imaging optical system is a zoom optical system, and preferably includes at least two lens groups whose intervals between adjacent groups change during zooming, on the reduced side of the intermediate image.

[0016] In the above aspect, it is preferable that the first adjustment group is composed of two or fewer lenses.

[0017] A projection display device according to another aspect of the present disclosure includes a light valve that outputs an optical image, and an imaging optical system according to any one of the above aspects, and the imaging optical system projects the optical image output from the light valve onto a screen.

[0018] An imaging device according to still another aspect of the present disclosure includes an imaging optical system according to any one of the above aspects.

[0019] Note that the “consisting of” and “comprising” in this specification are intended to include, in addition to the listed components, lenses that substantially do not have refractive power, optical elements other than lenses such as diaphragms, masks, filters, cover glasses, plane mirrors, and prisms, and mechanical parts such as lens flanges, lens barrels, imaging elements, and shake correction mechanisms. Also, a “lens group” may include optical elements other than lenses such as diaphragms, masks, filters, cover glasses, plane mirrors, and prisms.

[0020] In this specification, the "first adjustment group," "second adjustment group," "subgroup," and "lens group" are not limited to configurations consisting of multiple components, but may also consist of only one component, for example, a configuration consisting of a single lens. The "focal length" used in the conditional formulas refers to the paraxial focal length. "A lens with positive refractive power" and "positive lens" are synonymous. "A lens with negative refractive power" and "negative lens" are synonymous.

[0021] A "single lens" refers to a single, unbonded lens. However, a composite aspherical lens (a lens in which a spherical lens and an aspherical film formed on that spherical lens are integrally constructed and function as a single aspherical lens as a whole) is not considered a bonded lens and is treated as a single lens. Unless otherwise specified, the sign and surface shape of the refractive power for lenses including aspherical surfaces shall be those of the paraxial region.

[0022] The terms "d-line," "C-line," and "F-line" as used herein are emission lines, with the wavelength of the d-line being 587.56 nm (nanometers), the wavelength of the C-line being 656.27 nm (nanometers), and the wavelength of the F-line being 486.13 nm (nanometers). [Effects of the Invention]

[0023] According to this disclosure, it is possible to provide an imaging optical system having various adjustment mechanisms and maintaining high optical performance with well corrected aberrations associated with wide-angle lenses, a projection display device equipped with this imaging optical system, and an imaging device equipped with this imaging optical system. [Brief explanation of the drawing]

[0024] [Figure 1] This is a cross-sectional view corresponding to the imaging optical system of Example 1, showing the configuration and light beam of the imaging optical system according to one embodiment. [Figure 2] This figure shows examples of the first and second regions. [Figure 3] These are aberration diagrams of the imaging optical system in Example 1. [Figure 4]These are aberration diagrams before and after adjustment, showing an example where the second adjustment group of the imaging optical system in Example 1 is moved. [Figure 5] This figure shows the projection onto a curved screen using the imaging optical system of Example 1. [Figure 6] Figure 5 shows the astigmatism diagrams before and after adjustment in an example where the first adjustment group was moved in the state shown. [Figure 7] This figure shows the image projected onto another curved screen using the imaging optical system of Example 1. [Figure 8] Figure 7 shows the astigmatism diagrams before and after adjustment in an example where the first adjustment group was moved in the state shown in Figure 7. [Figure 9] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam according to a modified example of Example 1. [Figure 10] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 2. [Figure 11] These are aberration diagrams of the imaging optical system in Example 2. [Figure 12] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam according to a modified example of Example 2. [Figure 13] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 3. [Figure 14] These are aberration diagrams of the imaging optical system in Example 3. [Figure 15] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 4. [Figure 16] These are aberration diagrams of the imaging optical system in Example 4. [Figure 17] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 5. [Figure 18] These are aberration diagrams of the imaging optical system in Example 5. [Figure 19] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 6. [Figure 20] These are aberration diagrams of the imaging optical system in Example 6. [Figure 21] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 7. [Figure 22] These are aberration diagrams of the imaging optical system in Example 7. [Figure 23] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 8. [Figure 24] These are aberration diagrams of the imaging optical system in Example 8. [Figure 25] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 9. [Figure 26] These are aberration diagrams of the imaging optical system in Example 9. [Figure 27] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 10. [Figure 28] These are aberration diagrams of the imaging optical system in Example 10. [Figure 29] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 11. [Figure 30] These are aberration diagrams of the imaging optical system in Example 11. [Figure 31] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 12. [Figure 32] These are aberration diagrams of the imaging optical system in Example 12. [Figure 33] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 13. [Figure 34] These are aberration diagrams of the imaging optical system in Example 13. [Figure 35] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 14. [Figure 36] These are aberration diagrams of the imaging optical system in Example 14. [Figure 37] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 15. [Figure 38] These are aberration diagrams of the imaging optical system in Example 15. [Figure 39] This is a cross-sectional view showing the configuration of the imaging optical system and the light beam of Example 16. [Figure 40] These are aberration diagrams of the imaging optical system of Example 16. [Figure 41] This is a schematic diagram of a projection-type display device according to one embodiment. [Figure 42] This is a schematic diagram of a projection-type display device according to another embodiment. [Figure 43] This is a schematic diagram of a projection-type display device according to yet another embodiment. [Figure 44] This is a front perspective view of an imaging device according to one embodiment. [Figure 45] Figure 44 is a perspective view of the rear side of the imaging device shown. [Modes for carrying out the invention]

[0025] Embodiments of this disclosure will be described below with reference to the drawings.

[0026] Figure 1 shows the configuration and light beam in a cross-section including the optical axis Z of an imaging optical system according to one embodiment of the present disclosure. The configuration example shown in Figure 1 corresponds to Example 1 described later. In Figure 1, the light beams are shown as the light beam K0 of the minimum field of view and the light beam K1 of the maximum half-field of view. In the example in Figure 1, the light beam K0 of the minimum field of view is the on-axial light beam. In Figure 1, the left side is the magnification side and the right side is the reduction side.

[0027] The imaging optical system of this disclosure can be a projection optical system mounted on a projection display device to form an image projected onto a screen, or it can be an imaging optical system mounted on an imaging device to form an image of an object. In the following description, we will assume that the imaging optical system is used in the application of a projection optical system. In addition, in the following description, to avoid redundant explanations, "the imaging optical system of this disclosure" may be simply referred to as "the imaging optical system."

[0028] Figure 1 shows an example where the imaging optical system is mounted on a projection-type display device, with the optical component PP and the image display surface Sim of the light bulb positioned on the reduction side of the imaging optical system. The optical component PP is a component that is assumed to be a filter, cover glass, and color-compounding prism, etc. The optical component PP is a component that does not have refractive power, and a configuration without the optical component PP is also possible. The light bulb outputs an optical image, and this optical image is displayed as an image on the image display surface Sim.

[0029] In a projection-type display device, a light beam imprinted with image information on the image display surface Sim is incident on the imaging optical system via the optical component PP, and the image is projected onto a screen (not shown) by the imaging optical system. In this case, the image display surface Sim corresponds to the reduction-side conjugate plane, and the screen corresponds to the enlargement-side conjugate plane. In this specification, "screen" refers to the object onto which the projected image formed by the imaging optical system is projected. The screen may be a dedicated screen, or it may be the wall, floor, ceiling of a room, or the exterior wall of a building.

[0030] In this specification, "magnification side" refers to the screen side in the optical path, and "reduction side" refers to the image display surface (Sim) side in the optical path. In this specification, "magnification side" and "reduction side" are determined along the optical path, and this is also true for imaging optical systems with bent optical paths. "The most magnified side" means the most magnified side in terms of the order along the optical path, and does not mean the closest to the screen in terms of distance. To avoid redundancy in the following explanation, "from the magnification side to the reduction side along the optical path" may be written as "from the magnification side to the reduction side in order."

[0031] The imaging optical system in Figure 1 can image an image on the reducing conjugate plane as an intermediate image MI, and re-image the intermediate image MI as an enlarged image on the enlargement conjugate plane. In Figure 1, only a portion of the intermediate image MI near the optical axis is shown with a simplified dotted line. The intermediate image MI in Figure 1 shows its position on the optical axis and does not represent its exact shape. The imaging optical system in Figure 1 consists of a first optical system U1 and a second optical system U2, arranged from the enlargement side to the reducing side, with the intermediate image MI in between. This optical system for forming the intermediate image MI has the advantages of shortening the back focus of the first optical system U1 and reducing the lens diameter on the enlargement side of the first optical system U1.

[0032] As an example, in the example shown in Figure 1, the first optical system U1 consists of 13 lenses, and the second optical system U2 consists of 10 lenses. The second optical system U2 forms an image of the image displayed on the image display surface Sim as an intermediate image MI, and the first optical system U1 re-images the intermediate image MI as an enlarged image (i.e., a projected image) onto a screen not shown.

[0033] In the imaging optical system of this disclosure, the optical element positioned on the magnifying side is configured to be a lens. If a mirror with power, which is coaxial with other lenses, were to be positioned on the magnifying side of the imaging optical system, a problem would arise in that the light beam near the optical axis could not reach the screen and therefore could not be used for imaging. Therefore, the imaging optical system of this disclosure eliminates such a problem.

[0034] The imaging optical system of this disclosure includes a first adjustment group A1 and a second adjustment group A2 as adjustment mechanisms. The first adjustment group A1 moves along the optical axis Z when adjusting the imaging position of the first region Re1, which is the region of the magnified image that includes the farthest point from the optical axis Z. The second adjustment group A2 moves along the optical axis Z when adjusting the imaging position of the second region Re2, which is the region of the magnified image that includes the nearest point from the optical axis Z. Here, "nearest point from the optical axis Z" also includes points on the optical axis.

[0035] The first region Re1 is the region containing the imaging point of the light beam K1 with the largest half-angle of view in the magnified image, and the second region Re2 is the region containing the imaging point of the light beam K0 with the smallest angle of view in the magnified image. As an example, Figure 2 shows the first region Re1 and the second region Re2 in a plane perpendicular to the optical axis Z. In the example in Figure 2, the configuration is as follows: The magnified image is a large solid circle centered on the optical axis Z. The first region Re1 is a ring-shaped portion with relatively wide hatching between the large solid circle and the small solid circle. The second region Re2 is a dashed circle with relatively narrow hatching. The farthest point in the magnified image is a point on the circumference that forms the outer edge of the magnified image, and the first region Re1 includes these points. The nearest point in the magnified image is a point on the optical axis, and the second region Re2 includes this point.

[0036] However, the first region Re1 and the second region Re2 in the technology of this disclosure are not necessarily limited to the example in Figure 2. Compared to the example in Figure 2, the first region Re1 can have either a wide or narrow configuration, and the second region Re2 can also have either a wide or narrow configuration. For example, in the radial direction, the first region Re1 may be the region from 40% of the maximum image height to the maximum image height, and the second region Re2 may be the region from the optical axis Z to 50% of the maximum image height. In the example in Figure 2, the first region Re1 and the second region Re2 overlap in part, but in the technology of this disclosure, the first region Re1 and the second region Re2 do not have to overlap. For example, in the radial direction, the first region Re1 may be the region from 50% of the maximum image height to the maximum image height, and the second region Re2 may be the region from the optical axis Z to 50% of the maximum image height. Figure 2 shows an example where the second region Re2 includes the optical axis Z, but if the magnified image does not include the optical axis Z, a configuration in which the second region Re2 does not include the optical axis Z is also possible. Also, although Figure 2 shows a circular magnified image, the shape of the magnified image can be any shape, for example, a rectangle.

[0037] Since the first region Re1 is the region of the magnified image that includes the furthest point from the optical axis Z, the first adjustment group A1 can adjust the imaging position in the peripheral part of the magnified image. In ultra-wide-angle imaging optical systems, the change in the magnified image in response to changes in projection distance (the distance along the optical axis from the most magnified surface of the imaging optical system to the conjugate surface on the magnified side) differs greatly between the vicinity of the optical axis and the peripheral part. That is, in ultra-wide-angle imaging optical systems, the sensitivity to changes in imaging position in response to changes in projection distance is very small near the optical axis of the magnified image due to the deep depth of field, while the sensitivity to changes in field curvature in response to changes in projection distance is large in the peripheral part of the magnified image. For this reason, the first adjustment group A1 can function as a field curvature correction group that moves along the optical axis Z when correcting field curvature. Correction of field curvature is an important matter in wide-angle optical systems, so deploying the first adjustment group A1 as described above is advantageous for wide-angle applications.

[0038] It is preferable that the first adjustment group A1 is positioned on the magnification side of the intermediate image MI. That is, it is preferable that the first adjustment group A1 is positioned within the first optical system U1. In the first optical system U1, which is mainly responsible for widening the optical field, on-axis rays and off-axis rays are easily separated, and therefore the relative sensitivity difference regarding image plane changes between on-axis and off-axis tends to be large. Specifically, in the first optical system U1, the sensitivity to image plane changes when each adjustment group moves is significantly greater for off-axis image plane changes than for on-axis image plane changes. For this reason, positioning the first adjustment group A1 within the first optical system U1 rather than within the second optical system U2 makes it easier to achieve a greater effect in correcting image plane curvature.

[0039] In the example in Figure 1, the first adjustment group A1 consists of two subgroups, A1a and A1b. Subgroups A1a and A1b consist of the fourth and fifth lenses from the magnifying side, respectively. During adjustment, subgroups A1a and A1b move along the optical axis Z, changing their relative spacing. The horizontal arrows below subgroups A1a and A1b in Figure 1 indicate that subgroups A1a and A1b move individually along the optical axis Z, changing their relative spacing during adjustment. Thus, configuring the first adjustment group A1 to consist of multiple subgroups that move while changing the spacing between adjacent groups during adjustment is advantageous for achieving better adjustment.

[0040] The first adjustment group A1 preferably consists of two or fewer lenses. This is advantageous for reducing the weight of the first adjustment group A1, and makes it easier to suppress the complexity and size of the mechanism for moving the first adjustment group A1. It can also contribute to suppressing the size increase of the imaging optical system.

[0041] If the first adjustment group A1 consists of two lenses, and these two lenses are a positive lens and a negative lens, it is advantageous in suppressing fluctuations in chromatic aberration during adjustment. In this case, the positive lens and the negative lens constituting the first adjustment group A1 may be joined together, or they may both be single lenses. If the first adjustment group A1 consists of one lens, and this one lens is a positive lens, it is advantageous in reducing the size in the radial direction.

[0042] The second adjustment group A2 can adjust the image formation position near the optical axis of the magnified image, in other words, adjust the focus.

[0043] The second adjustment group A2 is positioned at the most retracted end of the imaging optical system. By making the lens group at the most retracted end of the imaging optical system movable, the back focus can be easily changed. In the example in Figure 1, the second adjustment group A2 consists of two lenses: the lens at the most retracted end and the second lens from the retracted end. The horizontal arrow below the second adjustment group A2 in Figure 1 indicates that the second adjustment group A2 moves along the optical axis Z during adjustment.

[0044] The second adjustment group A2 is configured as a group with a positive refractive power as a whole. By making the refractive power of the second adjustment group A2, which is positioned on the most retracted side, positive, it becomes easier to ensure the telecentricity on the retracted side of the imaging optical system and to reconcile this with the change in field curvature that occurs with changes in the imaging position near the optical axis.

[0045] The second adjustment group A2 may be configured to include at least two lenses. Including two or more lenses in the second adjustment group A2 is advantageous in suppressing performance changes associated with changes in the image formation position, and is particularly advantageous in suppressing changes in chromatic aberration.

[0046] The second adjustment group A2 may be configured to consist of two lenses. By having two lenses in the second adjustment group A2, the increase in the volume of the second adjustment group A2 within the limited space at the most compact side can be suppressed, and as a result, the realization of a mechanism for moving the second adjustment group A2 becomes easier. When the second adjustment group A2 consists of two lenses, the two lenses may be joined together, or both may be single lenses.

[0047] Since the second adjustment group A2 is a group that has a positive refractive power as a whole, the second adjustment group A2 includes at least one positive lens. If the second adjustment group A2 consists of two lenses, both lenses may be positive lenses, or the two lenses may be a positive lens and a negative lens.

[0048] When νp is the d-line reference Abbe number of at least one positive lens included in the second adjustment group A2, it is preferable that the imaging optical system satisfies the following condition (1). Generally, as the Abbe number decreases, the refractive index of optical materials increases. Therefore, by using materials with smaller Abbe numbers, it becomes easier to secure the refractive power of the lens without reducing the absolute value of the radius of curvature of the lens. If the absolute value of the radius of curvature is small, aberrations are more likely to occur, and the performance changes associated with the adjustment of the imaging position also become larger. By ensuring that the corresponding value of condition (1) does not exceed the upper limit, it is possible to suppress the occurrence of aberrations while securing appropriate refractive power for the second adjustment group A2, and as a result, the performance changes associated with the adjustment of the imaging position can be suppressed. It is even more preferable that the imaging optical system satisfies the following condition (1-1). By satisfying condition (1-1), it is possible to use materials with an Abbe number greater than the lower limit of condition (1-1). In general, optical materials have a lower refractive index as their Abbe number increases, which in turn allows for higher transmittance and lower material costs. νp<45 (1) 10 < νp < 45 (1-1)

[0049] When the focal length of the first adjustment group A1 is f1 and the focal length of the second adjustment group A2 is f2, it is preferable that the imaging optical system satisfies the following condition (2). However, if the first adjustment group A1 consists of multiple groups that move by changing the distance between adjacent groups during adjustment, the combined focal length of these multiple groups shall be taken as f1. Also, if the second adjustment group A2 consists of multiple groups that move by changing the distance between adjacent groups during adjustment, the combined focal length of these multiple groups shall be taken as f2. By ensuring that the corresponding value in condition (2) does not fall below the lower limit, the refractive power of the first adjustment group A1 does not become too strong relative to the refractive power of the second adjustment group A2, and therefore the change in the imaging position near the optical axis of the magnified image when the first adjustment group A1 moves does not become too large. Thus, even when this change in imaging position is corrected by the second adjustment group A2, it is possible to do so while suppressing the amount of movement of the second adjustment group A2 and balancing it with the overall performance of the imaging optical system. By ensuring that the corresponding value in condition (2) does not exceed the upper limit, the refractive power of the first adjustment group A1 does not become too weak relative to the refractive power of the second adjustment group A2, thereby suppressing the amount of movement of the first adjustment group A1, which is advantageous for miniaturizing the entire optical system. To obtain even better characteristics, it is more preferable that the imaging optical system satisfies the following condition (2-1). 0.5 < |f1 / f2| < 30 (2) 1 < |f1 / f2| < 8.5 (2-1)

[0050] If the paraxial transverse magnification of the first adjustment group A1 is β1, the combined paraxial transverse magnification of all optical systems on the side of the reduction from the first adjustment group A1 is β1r, and the paraxial transverse magnification of the second adjustment group A2 is β2, then it is preferable that the imaging optical system satisfies the following condition (3). However, if the first adjustment group A1 consists of multiple groups that move by changing the distance between adjacent groups during adjustment, the combined paraxial transverse magnification of these multiple groups shall be β1. Also, if the second adjustment group A2 consists of multiple groups that move by changing the distance between adjacent groups during adjustment, the combined paraxial transverse magnification of these multiple groups shall be β2. Condition (3) {(1-β1 2 )×β1r 2}{ represents the ratio of the amount of movement of the imaging position to the unit movement amount of the first adjustment group A1, that is, the sensitivity of the change in the imaging position when the first adjustment group A1 moves. Similarly, when the combined paraxial lateral magnification of all optical systems on the reduction side from the second adjustment group A2 is β2r, {(1 - β2 2 )×β2r 2}{ represents the sensitivity of the change in the imaging position when the second adjustment group A2 moves. However, in the imaging optical system of the present disclosure, since the second adjustment group A2 is arranged on the most reduction side, β2r = 1, and {(1 - β2 2 )×β2r 2}=(1 - β2 2 ). That is, the conditional expression (3) is an expression regarding the ratio of the above sensitivity of the first adjustment group A1 to the above sensitivity of the second adjustment group A2. Regarding the lower limit of the conditional expression (3), since the corresponding value of the conditional expression (3) is an absolute value, it becomes "0 <". By ensuring that the corresponding value of the conditional expression (3) does not exceed the upper limit, the sensitivity of the first adjustment group A1 with respect to the above sensitivity of the second adjustment group A2 does not become too large, so that the change in the imaging position near the optical axis of the magnified image when the first adjustment group A1 moves does not become too large. Therefore, even when correcting this change in the imaging position by the second adjustment group A2, it is possible to suppress the movement amount of the second adjustment group A2 while achieving a balance with the overall performance of the imaging optical system. In order to obtain better characteristics, it is more preferable for the imaging optical system to satisfy the following conditional expression (3-1). 0 < |{(1 - β1 2 )×β1r 2} / (1 - β2 2 )| < 0.5 (3) 0 < |{(1 - β1 2 )×β1r 2} / (1 - β2 2 )| < 0.15 (3-1)

[0051] When the focal length of the first optical system U1 is fU1 and the focal length of the imaging optical system is fw, it is preferable that the imaging optical system satisfies the following condition (4). However, if the imaging optical system is a variable magnification optical system, the values ​​of fU1 and fw are taken at the wide-angle end. By ensuring that the corresponding value in condition (4) does not fall below the lower limit, it becomes unnecessary to make the F-number of the first optical system U1 excessively small, which is advantageous for correcting spherical aberration and astigmatism. Also, by ensuring that the corresponding value in condition (4) does not fall below the lower limit, the beam diameter of the on-axial rays passing through the first optical system U1 becomes smaller, so the relative sensitivity difference regarding image plane changes between on-axis and off-axis, as described above, becomes larger, and the effect of correcting image plane curvature can be made greater. By ensuring that the corresponding value in condition (4) does not exceed the upper limit, the relay magnification when imaging the intermediate image MI does not become too large, so the size of the intermediate image MI can be suppressed. Therefore, the size of the first optical system U1 can be suppressed, and it is advantageous for correcting distortion and field curvature in the first optical system U1. To obtain even better characteristics, it is more preferable that the imaging optical system satisfies the following condition equation (4-1). 1 <fU1 / |fw|<5 (4) 1.5 <fU1 / |fw|<2.5 (4-1)

[0052] When the back focus of the imaging optical system in air equivalent distance is Bfw and the focal length of the imaging optical system is fw, it is preferable that the imaging optical system satisfies the following condition (5). However, if the imaging optical system is a variable magnification optical system, the values ​​for Bfw and fw should be those at the wide-angle end. Also, for the back focus, the reduction side is considered the back side. By ensuring that the corresponding value in condition (5) does not fall below the lower limit, the back focus does not become too short, making it easier to arrange color synthesis prisms, etc. It is even more preferable that the imaging optical system satisfies the following condition (5-1). By ensuring that the corresponding value in condition (5-1) does not fall below the lower limit, the above effect regarding the lower limit of condition (5) can be further enhanced. By ensuring that the corresponding value in condition (5-1) does not exceed the upper limit, it is possible to suppress the overall increase in size of the optical system, including the back focus. 3.5 <Bfw / |fw| (5) 4.5 <Bfw / |fw|<10 (5-1)

[0053] The imaging optical system preferably includes three single lenses with negative refractive power, arranged in sequence from the most magnified to the least magnified. This arrangement is advantageous for wide-angle applications. In the example shown in Figure 1, the most magnified lens L1, the second-to-last lens L2, and the third-to-last lens L3 are single lenses with negative refractive power. When the imaging optical system includes three single lenses with negative refractive power, arranged in sequence from the most magnified to the least magnified, it is preferable that the first adjustment group A1 is positioned on the less magnified side of the three single lenses with negative refractive power. Since negative lenses positioned on the magnified side and used for wide-angle applications tend to be large in diameter, if the first adjustment group A1 were constructed using the three single lenses with negative refractive power, the movement mechanism operating the first adjustment group A1 would become large. Therefore, it is preferable to construct the first adjustment group A1 using lenses different from the three single lenses with negative refractive power.

[0054] The imaging optical system may be configured as a variable magnification optical system, or for example, as a zoom optical system. In that case, it is preferable that the imaging optical system includes at least two lens groups on the reduction side of the intermediate image MI, the spacing between adjacent groups changes during magnification. By performing the magnification on the reduction side of the intermediate image MI, the magnification change can be achieved by changing the size of the intermediate image MI, thus allowing for an optically simple configuration.

[0055] As an example, in the example in Figure 1, the imaging optical system is a zoom lens, and the second optical system U2 includes two lens groups Va and Vb, the spacing between adjacent groups changes during magnification. In the example in Figure 1, lens group Va consists of one lens, the sixth from the reduction side, and lens group Vb consists of three lenses, the third to fifth from the reduction side. In the example in Figure 1, lens groups Va and Vb move towards the object along the optical axis Z when magnification is changed from the wide-angle end to the telephoto end. In Figure 1, the approximate direction of movement of each lens group when magnifying from the wide-angle end to the telephoto end is indicated by diagonally downward arrows below the lens groups that move during magnification.

[0056] In imaging optical systems, it is preferable that the reduction side is configured telecentrically. For example, projection-type display devices that project high-definition images often employ a so-called three-chip system, in which image display elements corresponding to the wavelengths of blue, green, and red colors are provided. To accommodate such a system, it is preferable that the reduction side is configured telecentrically. In imaging optical systems where the reduction side is strictly configured telecentrically, the principal rays from the most reduction-side surface of the imaging optical system toward the reduction-side conjugate plane are parallel to the optical axis Z.

[0057] However, in the art of this disclosure, "telecentric on the reduction side" is not limited to cases where the angle of the principal ray with respect to the optical axis Z is 0 degrees, but includes errors that are practically acceptable in the art to which the art of this disclosure belongs. The error may be, for example, a range of -3 degrees or more and +3 degrees or less for the angle of the principal ray with respect to the optical axis Z. In systems that do not include an aperture diaphragm St, when viewing the light beam in the direction from the expansion side to the reduction side, the telecentricity may be determined by using the angle bisector between the upper maximum ray and the lower maximum ray in the cross-section of the light beam that focuses at a point on the conjugate plane of the reduction side as a substitute for the principal ray.

[0058] The imaging optical system preferably has distortion aberrations within the range of -3% or more and +3% or less. Furthermore, the imaging optical system preferably has a maximum field of view of 120 degrees or more. If the imaging optical system is a variable magnification optical system, it is preferable that the maximum field of view at the wide-angle end is 120 degrees or more.

[0059] Note that the example shown in Figure 1 is just one example, and various modifications are possible without departing from the spirit of the technology of this disclosure. For example, the number of lenses included in the first adjustment group A1, the second adjustment group A2, the first optical system U1, the second optical system U2, and the lens group that moves during magnification may be different from the example in Figure 1. For miniaturization, the first adjustment group A1 may be configured to consist of a single lens. For simplification of the movable mechanism, the first adjustment group A1 may be configured to consist of multiple lenses that move integrally. For miniaturization, the second adjustment group A2 may be configured to consist of a single positive lens. If the second adjustment group A2 consists of a single positive lens, the magnifying surface of that positive lens may be configured to be a convex surface. The second adjustment group A2 may be configured to consist of multiple groups that move while changing the distance between adjacent groups during adjustment. The number of lens groups whose distance between adjacent groups changes during magnification may be different from the example in Figure 1.

[0060] When correcting field curvature, both the first adjustment group A1 and the second adjustment group A2 may be configured to move along the optical axis Z. When correcting field curvature, both the first adjustment group A1 and the second adjustment group A2 may be configured to move along the optical axis Z simultaneously. Alternatively, the second adjustment group A2 may move along the optical axis Z, and then the first adjustment group A1 may move along the optical axis Z to correct the field curvature.

[0061] The imaging optical system may be configured to include an optical path bending member that bends the optical path. For example, since a relatively large air gap can be secured at a position adjacent to the intermediate image MI, it is easy to place a member at this position, so the optical path bending member may be placed at a position adjacent to the intermediate image MI. Including an optical path bending member can contribute to miniaturization of the entire optical system. Examples of optical path bending members include mirrors and prisms with reflective surfaces.

[0062] The angle at which the optical path of the optical path bending member is bent can be set arbitrarily, but it may be set to 90 degrees, for example. Setting the bending angle to 90 degrees makes it possible to create a structure that is easy to manufacture. Note that this "90 degrees" includes a practically acceptable error in the art to which the technology of this disclosure belongs. The error may be in the range of -5 degrees or more and +5 degrees or less, for example.

[0063] The preferred and possible configurations described above can be combined in any way and are preferably selected as appropriate according to the required specifications. The preferred conditional expressions that the imaging optical system of this disclosure satisfies are not limited to those described in formula form, but include all conditional expressions obtained by arbitrarily combining lower and upper limits from the preferred and more preferred conditional expressions.

[0064] A preferred first aspect of the present disclosure is an imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image MI and re-imaging the intermediate image MI as an enlarged image on an enlargement conjugate plane, wherein the optical element positioned furthest from the enlargement side is a lens, and the system comprises a first adjustment group A1 that moves along the optical axis Z when adjusting the imaging position of a region of the enlarged image that includes the farthest point from the optical axis Z, and a second adjustment group A2 that moves along the optical axis Z when adjusting the imaging position of a region of the enlarged image that includes the nearest point from the optical axis Z, wherein the second adjustment group A2 includes at least two lenses, has a positive refractive power as a whole, and is positioned furthest from the enlargement side.

[0065] A preferred second aspect of the present disclosure is an imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image MI and re-imaging the intermediate image MI as an enlarged image on an enlargement conjugate plane, wherein the optical element positioned furthest from the enlargement side is a lens, and the system comprises a first adjustment group A1 that moves along the optical axis Z when adjusting the imaging position of a region of the enlarged image that includes the farthest point from the optical axis Z, and a second adjustment group A2 that moves along the optical axis Z when adjusting the imaging position of a region of the enlarged image that includes the nearest point from the optical axis Z, wherein the second adjustment group A2 includes at least one positive lens, has a positive refractive power as a whole, is positioned furthest from the enlargement side, and satisfies the above condition (1).

[0066] Next, embodiments of the imaging optical system of this disclosure will be described with reference to the drawings. Note that the reference numerals in the cross-sectional views of each embodiment are used independently for each embodiment to avoid complexity in the explanation and drawings due to the increasing number of digits in the reference numerals. Therefore, even if the same reference numerals are used in the drawings of different embodiments, they do not necessarily represent the same configuration.

[0067] [Example 1] The configuration of the imaging optical system and the cross-sectional view of the light beam in Example 1 are shown in Figure 1, and the method of illustration and configuration are as described above, so some redundant explanations will be omitted here. The imaging optical system in Example 1 is a variable magnification optical system, and consists of a first optical system U1 and a second optical system U2, arranged in order from the magnification side to the reduction side, with an intermediate image MI formed inside.

[0068] The first optical system U1 includes the first adjustment group A1. The first adjustment group A1 consists of subgroups A1a and A1b, which move while changing their relative spacing during adjustment. Each subgroup A1a and subgroup A1b consists of one lens. The second optical system U2 includes the second adjustment group A2 at the most reduced side. The second optical system U2 includes lens groups Va and Vb, which move while changing the spacing between adjacent groups during magnification. During magnification, lenses other than lens groups Va and Vb are fixed relative to the image display surface Sim.

[0069] Tables 1A and 1B show the basic lens data for the imaging optical system of Example 1, Table 2 shows the specifications and variable plane spacing, Table 3 shows the aspherical coefficient, and Table 4 shows an overview of each adjustment group.

[0070] The basic lens data table is divided into two tables, Table 1A and Table 1B, to avoid making a single table too long. Table 1A shows the first optical system U1, and Table 1B shows the second optical system U2 and the optical component PP. The basic lens data table is written as follows: The Sn column shows the surface number, where the surface on the widest side is the first surface and the number increases by one as you move toward the narrower side. The R column shows the radius of curvature of each surface. The D column shows the interplanar spacing on the optical axis between each surface and the surface adjacent to it on the narrower 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 with respect to the d line.

[0071] In the basic lens data table, the sign of the radius of curvature of a surface with a convex shape facing the magnification side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the reduction side is negative. The value in the bottom column of D in Table 1B is the distance between the surface on the reduction side in the table and the image display surface Sim. In the basic lens data table, the variable surface interval during magnification is represented by the symbol DD[ ], and the number of the magnified surface of this interval is written in column D inside the [ ]. Table 1 shows the data for a projection distance of 1.1m (meters).

[0072] Table 2 shows the magnification ratio Zr, the absolute value of the focal length |f|, the F-number FNo., and the maximum angle of view 2ω relative to the d line. The maximum angle of view is twice the maximum half-angle of view. The [°] in the 2ω column indicates that the unit is degrees. In Table 2, the WIDE column shows the values ​​at the wide-angle end, and the TELE column shows the values ​​at the telephoto end.

[0073] In the basic lens data, the aspherical surface number is marked with an asterisk (*), and the value of the paraxial radius of curvature is listed in the column for the radius of curvature of the aspherical surface. In Table 3, the row labeled Sn shows the aspherical surface number, and the rows labeled KA and Am show the numerical value of the aspherical coefficient for each aspherical surface. Note that m in Am is an integer greater than or equal to 3 and varies depending on the surface. For example, in the first surface of Example 1, m = 3, 4, 5, ..., 20. The numerical value of the aspherical coefficient in Table 3, "E±n" (n: integer), is "×10 ±n This means "[...]. KA and Am are the aspheric coefficients in the aspheric equation expressed by the following formula. Zd = C × h2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspherical depth (length of the perpendicular line drawn from a point on the aspherical surface at height h to a plane perpendicular to the optical axis Z to which the aspherical surface tangent is located). h: Height (distance from the optical axis Z to the lens surface) C: Reciprocal of the radius of paraxial curvature KA, Am: Aspherical coefficients Therefore, the Σ in aspherical formulas represents the summation with respect to m.

[0074] Table 4 shows an overview of the first adjustment group A1 and the second adjustment group A2. Since the first adjustment group A1 in Example 1 consists of two subgroups, subgroup A1a and subgroup A1b, the number of lenses and Sn columns in Table 4 are shown separately for each subgroup. The number of lenses column shows the number of lenses that make up each group. The Sn column shows the face number in the basic lens data table for the lenses that make up each group. For example, "7-8" in the Sn column of Table 4 indicates the lenses corresponding to the 7th and 8th faces in the basic lens data table. For adjustment groups that include multiple lenses, the movement method column is indicated as "moves individually" or "moves as a whole" depending on how they move during adjustment. For example, in Example 1, subgroups A1a and A1b that make up the first adjustment group A1 move individually by changing their mutual spacing during adjustment, so the movement method column for the first adjustment group A1 is indicated as "moves individually". Since the multiple lenses constituting the second adjustment group A2 in Example 1 move as a single unit, the column for the movement mode of the second adjustment group A2 states "move as a single unit." In this specification, "move as a single unit" means that they move simultaneously in the same direction by the same amount.

[0075] In the data in each table, degrees are used as the unit for angles and millimeters as the unit for lengths. However, since optical systems can be used with proportional magnification or reduction, other appropriate units can also be used. Furthermore, the values ​​in the tables below are rounded to a predetermined number of decimal places.

[0076] [Table 1A]

[0077] [Table 1B]

[0078] [Table 2]

[0079] [Table 3]

[0080] [Table 4]

[0081] Figure 3 shows the aberration diagrams for the imaging optical system of Example 1 at a projection distance of 1.1 m (meters). In Figure 3, the upper row labeled "WIDE" shows the aberration diagrams at the wide-angle end, and the lower row labeled "TELE" shows the aberration diagrams at the telephoto end. In Figure 3, from left to right, the diagrams show spherical aberration, astigmatism, distortion, and chromatic aberration. In the spherical aberration diagram, the 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, the aberration related to the d-line in the sagittal direction is shown by a solid line, and the aberration related to the d-line in the tangential direction is shown by a short dashed line. In the distortion diagram, the aberration related to the d-line is shown by a solid line. In the chromatic aberration diagram, the 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-number value is shown after "FNo.=". In other aberration diagrams, the value of the maximum half-angle is shown after "ω=".

[0082] Figure 4 shows the aberration diagrams before and after adjustment in an example where the second adjustment group A2 was moved and adjustment was performed. The top row of Figure 4, labeled "Before Adjustment," shows the aberration diagrams in the state before adjustment. These "Before Adjustment" aberration diagrams are the same as the aberration diagrams at the wide-angle end in Figure 3, but with the horizontal axis scale changed. The second row from the top of Figure 4, labeled "After Adjustment (Moved 0.5mm towards Reduction)," shows the aberration diagrams in the state after moving the second adjustment group A2 0.5mm (millimeters) towards reduction from the state before adjustment. The third row from the top of Figure 4, labeled "After Adjustment (Moved 0.5mm towards Enlargement)," shows the aberration diagrams in the state after moving the second adjustment group A2 0.5mm (millimeters) towards enlargement from the state before adjustment. Note that all aberration diagrams in Figure 4 are aberrations at the same image plane position.

[0083] Figures 5 to 8 illustrate an example of adjustment performed by moving the first adjustment group A1. Figure 5 shows the projection onto a curved screen 5 with a convex shape facing the magnification side using the imaging optical system of Example 1. In Figure 5, the screen 5 has a radius of curvature of 5000 mm and a projection distance of 1.1 m. The astigmatism diagram before adjustment when projected onto the screen 5 in Figure 5 is shown on the left side of Figure 6, and the astigmatism diagram after adjustment performed by moving the first adjustment group A1 is shown on the right side of Figure 6.

[0084] Figure 7 shows the projection onto a curved screen 6 with a convex shape facing the reduction side, using the imaging optical system of Example 1. In Figure 7, the screen 6 has a radius of curvature of -15000 mm and a projection distance of 1.1 m. The astigmatism diagram before adjustment when projected onto the screen 6 in Figure 7 is shown on the left side of Figure 8, and the astigmatism diagram after adjustment by moving the first adjustment group A1 is shown on the right side of Figure 8.

[0085] Figure 9 shows the configuration and light beam at the wide-angle end of the imaging optical system according to a modified example of Example 1. The imaging optical system in Figure 9 differs from the imaging optical system of Example 1 in that it includes two mirrors, Mr1 and Mr2, and the optical path is bent by mirrors Mr1 and Mr2. The other configurations of the imaging optical system in Figure 9 are the same as those of the imaging optical system of Example 1. In Figure 9, the arrows indicating movement are omitted. By bending the optical path, a compact configuration is possible.

[0086] The symbols, meanings, methods of description, and methods of illustration for each data point in Example 1 and its modified form described above are basically the same in the following examples unless otherwise specified, so redundant explanations will be omitted below.

[0087] [Example 2] Figure 10 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 2. The imaging optical system of Example 2 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two subgroups, A1a and A1b, which move along the optical axis Z by changing their mutual spacing during adjustment. Subgroup A1a consists of a single lens, the fourth from the magnification side. Subgroup A1b consists of a single lens, the fifth from the magnification side. The second optical system U2 includes a second adjustment group A2 on the reduction side. The second adjustment group A2 consists of two lenses, the lens on the reduction side and the lens second from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0088] The imaging optical system of Example 2 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0089] Regarding the imaging optical system of Example 2, the basic lens data is shown in Tables 5A and 5B, the specifications and variable plane spacing are shown in Table 6, the aspherical coefficient is shown in Table 7, and an overview of each adjustment group is shown in Table 8. In addition, the aberration diagrams for each state at a projection distance of 1.1 m (meters) are shown in Figure 11.

[0090] [Table 5A]

[0091] [Table 5B]

[0092] [Table 6]

[0093] [Table 7]

[0094] [Table 8]

[0095] Figure 12 shows the configuration and light beam at the wide-angle end of the imaging optical system according to a modified example of Example 2. The imaging optical system in Figure 12 differs from the imaging optical system of Example 2 in that it includes two mirrors, Mr1 and Mr2, and the optical path is bent by mirrors Mr1 and Mr2. The other configurations of the imaging optical system in Figure 12 are the same as those of the imaging optical system of Example 2. By bending the optical path, a compact configuration is possible.

[0096] [Example 3] Figure 13 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 3. The imaging optical system in Example 3 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses, the 8th and 9th lenses from the magnification side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of two lenses, the lens at the furthest reduction side and the second lens from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0097] The imaging optical system of Example 3 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0098] Regarding the imaging optical system of Example 3, the basic lens data is shown in Tables 9A and 9B, the specifications and variable plane spacing are shown in Table 10, the aspherical coefficient is shown in Table 11, and an overview of each adjustment group is shown in Table 12. In addition, the aberration diagrams for each state at a projection distance of 1.5 m (meters) are shown in Figure 14.

[0099] [Table 9A]

[0100] [Table 9B]

[0101] [Table 10]

[0102] [Table 11]

[0103] [Table 12]

[0104] [Example 4] Figure 15 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 4. The imaging optical system of Example 4 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a prism Pr and multiple lenses. The first adjustment group A1 consists of the 11th lens from the magnification side in the first optical system U1. The second optical system U2 includes the second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of two lenses: the lens at the furthest reduction side and the second lens from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0105] The imaging optical system of Example 4 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses and prisms Pr are fixed relative to the image display plane Sim. Lens group Vb includes an aperture diaphragm St.

[0106] Tables 13A and 13B show the basic lens data for the imaging optical system of Example 4, Table 14 shows the specifications and variable plane spacing, Table 15 shows the aspherical coefficient, and Table 16 shows an overview of each adjustment group. Figure 16 also shows the aberration diagrams for a projection distance of 1.1 m (meters). In the table of basic lens data, the column for the plane number corresponding to the aperture diaphragm St shows the plane number and the phrase (St), and this notation is the same in subsequent examples that include the aperture diaphragm St.

[0107] [Table 13A]

[0108] [Table 13B]

[0109] [Table 14]

[0110] [Table 15]

[0111] [Table 16]

[0112] [Example 5] Figure 17 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 5. The imaging optical system of Example 5 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses: the fifth lens and the sixth lens from the magnification side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of two lenses: the lens at the furthest reduction side and the second lens from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0113] The imaging optical system in Example 5 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0114] Regarding the imaging optical system of Example 5, the basic lens data is shown in Tables 17A and 17B, the specifications and variable plane spacing are shown in Table 18, the aspherical coefficient is shown in Table 19, and an overview of each adjustment group is shown in Table 20. In addition, the aberration diagrams for each state at a projection distance of 0.8 m (meters) are shown in Figure 18.

[0115] [Table 17A]

[0116] [Table 17B]

[0117] [Table 18]

[0118] [Table 19]

[0119] [Table 20]

[0120] [Example 6] Figure 19 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 6. The imaging optical system of Example 6 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses, the fifth and sixth lenses from the magnification side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of two lenses, the lens at the furthest reduction side and the second lens from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0121] The imaging optical system of Example 6 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0122] Regarding the imaging optical system of Example 6, the basic lens data is shown in Tables 21A and 21B, the specifications and variable plane spacing are shown in Table 22, the aspherical coefficient is shown in Table 23, and an overview of each adjustment group is shown in Table 24. In addition, the aberration diagrams for the state at a projection distance of 0.8 m (meters) are shown in Figure 20.

[0123] [Table 21A]

[0124] [Table 21B]

[0125] [Table 22]

[0126] [Table 23]

[0127] [Table 24]

[0128] [Example 7] Figure 21 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 7. The imaging optical system of Example 7 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two subgroups, A1a and A1b, which move along the optical axis Z by changing their mutual spacing during adjustment. Subgroup A1a consists of a single lens, the fourth from the magnification side. Subgroup A1b consists of a single lens, the fifth from the magnification side. The second optical system U2 includes a second adjustment group A2 on the furthest reduction side. The second adjustment group A2 consists of two lenses: the lens on the furthest reduction side and the lens second from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0129] The imaging optical system of Example 7 is a variable magnification optical system. During magnification, lens groups Va, Vb, Vc, and Vd in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim. Lens group Vd includes an aperture diaphragm St.

[0130] Regarding the imaging optical system of Example 7, the basic lens data is shown in Tables 25A and 25B, the specifications and variable plane spacing are shown in Table 26, the aspherical coefficient is shown in Table 27, and an overview of each adjustment group is shown in Table 28. In addition, the aberration diagrams for each state at a projection distance of 0.5 m (meters) are shown in Figure 22.

[0131] [Table 25A]

[0132] [Table 25B]

[0133] [Table 26]

[0134] [Table 27]

[0135] [Table 28]

[0136] [Example 8] Figure 23 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 8. The imaging optical system of Example 8 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two subgroups, A1a and A1b, which move along the optical axis Z by changing their mutual spacing during adjustment. Subgroup A1a consists of a single lens, the fourth from the magnification side. Subgroup A1b consists of a single lens, the fifth from the magnification side. The second optical system U2 includes a second adjustment group A2 on the furthest reduction side. The second adjustment group A2 consists of two lenses, the lens on the furthest reduction side and the lens second from the reduction side. The two lenses of the second adjustment group A2 move integrally along the optical axis Z during adjustment.

[0137] The imaging optical system of Example 8 is a fixed-focus optical system. The second optical system U2 includes an aperture diaphragm St. For the imaging optical system of Example 8, the basic lens data is shown in Tables 29A and 29B, the specifications are shown in Table 30, the aspherical coefficients are shown in Table 31, and an overview of each adjustment group is shown in Table 32. In addition, the aberration diagrams for each state at a projection distance of 0.8 m (meters) are shown in Figure 24.

[0138] [Table 29A]

[0139] [Table 29B]

[0140] [Table 30]

[0141] [Table 31]

[0142] [Table 32]

[0143] [Example 9] Figure 25 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 9. The imaging optical system of Example 9 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two subgroups, A1a and A1b, which move along the optical axis Z by changing their mutual spacing during adjustment. Subgroup A1a consists of a single lens, the fourth from the magnification side. Subgroup A1b consists of a single lens, the fifth from the magnification side. The second optical system U2 includes a second adjustment group A2 on the reduction side. The second adjustment group A2 consists of a single lens on the reduction side.

[0144] The imaging optical system of Example 9 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0145] Regarding the imaging optical system of Example 9, the basic lens data is shown in Tables 33A and 33B, the specifications and variable plane spacing are shown in Table 34, the aspherical coefficient is shown in Table 35, and an overview of each adjustment group is shown in Table 36. In addition, the aberration diagrams for each state at a projection distance of 1.1 m (meters) are shown in Figure 26.

[0146] [Table 33A]

[0147] [Table 33B]

[0148] [Table 34]

[0149] [Table 35]

[0150] [Table 36]

[0151] [Example 10] Figure 27 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 10. The imaging optical system of Example 10 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two subgroups, A1a and A1b, which move along the optical axis Z by changing their mutual spacing during adjustment. Subgroup A1a consists of a single lens, the fourth from the magnification side. Subgroup A1b consists of a single lens, the fifth from the magnification side. The second optical system U2 includes a second adjustment group A2 on the reduction side. The second adjustment group A2 consists of a single lens on the reduction side.

[0152] The imaging optical system of Example 10 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0153] Regarding the imaging optical system of Example 10, the basic lens data is shown in Tables 37A and 37B, the specifications and variable plane spacing are shown in Table 38, the aspherical coefficient is shown in Table 39, and an overview of each adjustment group is shown in Table 40. In addition, the aberration diagrams for each state at a projection distance of 1.1 m (meters) are shown in Figure 28.

[0154] [Table 37A]

[0155] [Table 37B]

[0156] [Table 38]

[0157] [Table 39]

[0158] [Table 40]

[0159] [Example 11] Figure 29 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 11. The imaging optical system of Example 11 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses, the 8th and 9th lenses from the magnification side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 on the reduction side. The second adjustment group A2 consists of one lens on the reduction side.

[0160] The imaging optical system in Example 11 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0161] Regarding the imaging optical system of Example 11, the basic lens data is shown in Tables 41A and 41B, the specifications and variable plane spacing are shown in Table 42, the aspherical coefficient is shown in Table 43, and an overview of each adjustment group is shown in Table 44. In addition, the aberration diagrams for each state at a projection distance of 1.5 m (meters) are shown in Figure 30.

[0162] [Table 41A]

[0163] [Table 41B]

[0164]

Table 42

[0165]

Table 43

[0166]

Table 44

[0167] [Example 12] The configuration of the imaging optical system of Example 12 and a cross-sectional view of the light beam are shown in FIG. 31. The imaging optical system of Example 12 consists of a first optical system U1 and a second optical system U2 in order from the magnifying side to the reducing side with an intermediate image MI formed inside sandwiched therebetween. The first optical system U1 includes a prism Pr and a plurality of lenses. The first adjustment group A1 consists of the 11th single lens from the magnifying side within the first optical system U1. The second optical system U2 includes a second adjustment group A2 on the most reducing side. The second adjustment group A2 consists of the single lens on the most reducing side.

[0168] The imaging optical system of Example 12 is a zoom optical system. During zooming, the distance between the lens groups Va and Vb within the second optical system U2 changes with respect to the adjacent groups and they move along the optical axis Z, and the other lenses are fixed with respect to the image display surface Sim. The lens group Vb includes an aperture stop St.

[0169] Regarding the imaging optical system of Example 12, the basic lens data are shown in Tables 45A and 45B, the specifications and variable surface intervals are shown in Table 46, the aspherical coefficients are shown in Table 47, and the outline of each adjustment group is shown in Table 48. Also, each aberration diagram in the state where the projection distance is 1.1 m (meter) is shown in FIG. 32.

[0170]

Table 45A

[0171] [Table 45B]

[0172] [Table 46]

[0173] [Table 47]

[0174] [Table 48]

[0175] [Example 13] Figure 33 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 13. The imaging optical system of Example 13 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses, the 5th and 6th lenses from the magnification side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 on the reduction side. The second adjustment group A2 consists of one lens on the reduction side.

[0176] The imaging optical system of Example 13 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim. Lens group Vb includes an aperture diaphragm St.

[0177] Regarding the imaging optical system of Example 13, the basic lens data is shown in Tables 49A and 49B, the specifications and variable plane spacing are shown in Table 50, the aspherical coefficient is shown in Table 51, and an overview of each adjustment group is shown in Table 52. In addition, the aberration diagrams for each state at a projection distance of 0.8 m (meters) are shown in Figure 34.

[0178]

Table 49A

[0179]

Table 49B

[0180]

Table 50

[0181]

Table 51

[0182]

Table 52

[0183] [Example 14] The configuration of the imaging optical system of Example 14 and a cross-sectional view of the light beam are shown in FIG. 35. The imaging optical system of Example 14 includes a first optical system U1 and a second optical system U2 in order from the magnifying side to the reducing side with an intermediate image MI formed inside sandwiched therebetween. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of two lenses, namely the fifth lens and the sixth lens from the magnifying side. The two lenses of the first adjustment group A1 move integrally along the optical axis Z during adjustment. The second optical system U2 includes a second adjustment group A2 on the most reducing side. The second adjustment group A2 consists of one lens on the most reducing side.

[0184] The imaging optical system of Example 14 is a zoom optical system. During zooming, the lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the distance between adjacent groups, and the other lenses are fixed with respect to the image display surface Sim. The lens group Vb includes the aperture stop St.

[0185] Tables 53A and 53B show the basic lens data for the imaging optical system of Example 14, Table 54 shows the specifications and variable plane spacing, Table 55 shows the aspherical coefficient, and Table 56 shows an overview of each adjustment group. Figure 36 shows the aberration diagrams for each state at a projection distance of 0.8 m (meters).

[0186] [Table 53A]

[0187] [Table 53B]

[0188] [Table 54]

[0189] [Table 55]

[0190] [Table 56]

[0191] [Example 15] Figure 37 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 15. The imaging optical system of Example 15 consists of a first optical system U1 and a second optical system U2, arranged in order from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of a single lens, the sixth from the magnification side. The second optical system U2 includes a second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of a single lens at the furthest reduction side.

[0192] The imaging optical system of Example 15 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0193] Regarding the imaging optical system of Example 15, the basic lens data is shown in Tables 57A and 57B, the specifications and variable plane spacing are shown in Table 58, the aspherical coefficient is shown in Table 59, and an overview of each adjustment group is shown in Table 60. In addition, the aberration diagrams for each state at a projection distance of 0.9 m (meters) are shown in Figure 38.

[0194] [Table 57A]

[0195] [Table 57B]

[0196] [Table 58]

[0197] [Table 59]

[0198] [Table 60]

[0199] [Example 16] Figure 39 shows the configuration of the imaging optical system and a cross-sectional view of the light beam in Example 16. The imaging optical system of Example 16 consists of a first optical system U1 and a second optical system U2, arranged from the magnification side to the reduction side, with an intermediate image MI formed inside. The first optical system U1 includes a first adjustment group A1. The first adjustment group A1 consists of a single lens, the sixth from the magnification side. The second optical system U2 includes a second adjustment group A2 at the furthest reduction side. The second adjustment group A2 consists of a single lens at the furthest reduction side.

[0200] The imaging optical system of Example 16 is a variable magnification optical system. During magnification, lens groups Va and Vb in the second optical system U2 move along the optical axis Z by changing the spacing between adjacent groups, while the other lenses are fixed relative to the image display plane Sim.

[0201] Regarding the imaging optical system of Example 16, the basic lens data is shown in Tables 61A and 61B, the specifications and variable plane spacing are shown in Table 62, the aspherical coefficient is shown in Table 63, and an overview of each adjustment group is shown in Table 64. In addition, the aberration diagrams for each state at a projection distance of 0.9 m (meters) are shown in Figure 40.

[0202] [Table 61A]

[0203] [Table 61B]

[0204] [Table 62]

[0205] [Table 63]

[0206] [Table 64]

[0207] In the above, as modifications of Examples 1 and 2, imaging optical systems with a bent optical path were described with reference to drawings. Although not shown in the drawings, similar modifications are possible for other embodiments. For example, similar to the modification of Example 1, the configurations of the imaging optical systems in Examples 5, 6, 7, 8, 9, 10, 13, and 14 can be modified by placing mirrors inside the imaging optical systems. Furthermore, the configurations of the imaging optical systems in Examples 4 and 12 can be modified by replacing the prism Pr with a prism having a reflective surface inside.

[0208] Table 65 shows the corresponding values ​​for the conditional equations (1) to (5) of the imaging optical systems in Examples 1 to 16. Table 65 shows the values ​​when the d-line is used as the reference. The corresponding values ​​of the examples shown in Table 65 may be used as the upper or lower limit of the conditional equation to set a preferred range for the conditional equation.

[0209] [Table 65]

[0210] The imaging optical systems of Examples 1 to 16 have a first adjustment group A1 and a second adjustment group A2, allowing for various adjustments. Furthermore, the imaging optical systems of Examples 1 to 16 have a maximum field of view of 120 degrees or more, achieving wide-angle capabilities while effectively correcting various aberrations and realizing high optical performance.

[0211] The imaging optical system used in projection-type display devices requires good aberration correction to match the resolution of the light bulb of the projection-type display device. Furthermore, from the perspective of improving the flexibility of setting the distance to the screen and ease of installation in indoor spaces, there is a growing demand for imaging optical systems that have a wider field of view and high optical performance with good correction of various aberrations. On the other hand, in order to cope with the increasing brightness of projection-type display devices, interchangeable lens systems that allow the imaging optical system to be changed depending on the application are also widely used. However, in systems using interchangeable lens systems, as the angle of view of the imaging optical system is widened, the impact on optical performance due to variations in the mounting surface cannot be ignored. Therefore, various adjustment mechanisms such as correction of field curvature and focus adjustment are required for the imaging optical system. In contrast, the imaging optical systems of Examples 1 to 16 described above have two types of adjustment groups and can satisfy the above requirements by ensuring a sufficiently wide field of view that can meet the demands of today while good correction of various aberrations associated with widening the angle of view.

[0212] Next, a projection-type display device according to an embodiment of the present disclosure will be described. Figure 41 is a schematic configuration diagram of a projection-type display device according to one embodiment of the present disclosure. The projection-type display device 100 shown in Figure 41 has an imaging optical system 10 according to an embodiment of the present disclosure, a light source 15, and transmissive display elements 11a to 11c as light bulbs that output optical images corresponding to each color of light. The projection-type display device 100 also has dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, condenser lenses 16a to 16c, and total reflection mirrors 18a to 18c for deflecting the optical path. Note that the imaging optical system 10 is shown schematicly in Figure 41. An integrator is placed between the light source 15 and the dichroic mirror 12, but it is not shown in Figure 41.

[0213] White light from light source 15 is decomposed into three color light beams (blue light, green light, and red light) by dichroic mirrors 12 and 13. These beams then pass through condenser lenses 16a to 16c and are incident on transmissive display elements 11a to 11c corresponding to each color light beam, where they are modulated. After being color-combined by a cross dichroic prism 14, the light beams are incident on the imaging optical system 10. The imaging optical system 10 projects an optical image based on the modulated light modulated by the transmissive display elements 11a to 11c onto the screen 105.

[0214] Figure 42 is a schematic diagram of a projection display device according to another embodiment of the present disclosure. The projection display device 200 shown in Figure 42 includes an imaging optical system 210 according to the present disclosure, a light source 215, and DMD (Digital Micromirror Device: registered trademark) elements 21a to 21c as light bulbs that output optical images corresponding to each color of light. The projection display device 200 also includes TIR (Total Internal Reflection) prisms 24a to 24c for color separation and color synthesis, and a polarization separation prism 25 for separating illumination light and projection light. Note that Figure 42 schematically illustrates the imaging optical system 210. An integrator is placed between the light source 215 and the polarization separation prism 25, but its illustration is omitted in Figure 42.

[0215] White light from the light source 215 is reflected by the reflective surface inside the polarization separation prism 25, and then decomposed into three color light beams (blue light, green light, and red light) by the TIR prisms 24a to 24c. Each of the decomposed color light beams is incident on the corresponding DMD elements 21a to 21c, modulated, and then passes through the TIR prisms 24a to 24c again in the reverse direction for color synthesis. After that, it passes through the polarization separation prism 25 and is incident on the imaging optical system 210. The imaging optical system 210 projects an optical image based on the modulated light modulated by the DMD elements 21a to 21c onto the screen 205.

[0216] Figure 43 is a schematic diagram of a projection display device according to yet another embodiment of the present disclosure. The projection display device 300 shown in Figure 43 includes an imaging optical system 310 according to the present disclosure, a light source 315, and reflective display elements 31a to 31c as light bulbs that output optical images corresponding to each color of light. The projection display device 300 also includes dichroic mirrors 32 and 33 for color separation, a cross dichroic prism 34 for color synthesis, a total reflection mirror 38 for optical path deflection, and polarization separation prisms 35a to 35c. Note that the imaging optical system 310 is shown schematicly in Figure 43. An integrator is placed between the light source 315 and the dichroic mirror 32, but it is not shown in Figure 43.

[0217] White light from light source 315 is decomposed into three color light beams (blue light, green light, and red light) by dichroic mirrors 32 and 33. Each color light beam after decomposition passes through polarization separation prisms 35a to 35c and is incident on reflective display elements 31a to 31c corresponding to each color light beam, where it is modulated. After being color-combined by a cross dichroic prism 34, it is incident on the imaging optical system 310. The imaging optical system 310 projects an optical image based on the modulated light modulated by the reflective display elements 31a to 31c onto the screen 305.

[0218] Figures 44 and 45 are external views of a camera 400, which is an imaging device according to one embodiment of the present disclosure. Figure 44 shows a perspective view of the camera 400 from the front, and Figure 45 shows a perspective view of the camera 400 from the rear. The camera 400 is a mirrorless single-lens reflex digital camera with a removable interchangeable lens 48. The interchangeable lens 48 houses an imaging optical system 49 according to an embodiment of the present disclosure within the lens barrel.

[0219] The camera 400 includes a camera body 41, on which a shutter button 42 and a power button 43 are provided on the top surface of the camera body 41. The rear of the camera body 41 is provided with an operation unit 44, an operation unit 45, and a display unit 46. The display unit 46 displays captured images and images within the field of view before capture.

[0220] A shooting aperture is provided in the center of the front of the camera body 41, into which light from the subject being photographed enters. A mount 47 is provided at a position corresponding to the shooting aperture, and an interchangeable lens 48 is attached to the camera body 41 via the mount 47.

[0221] The camera body 41 contains an image sensor (not shown), such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), which outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 48; a signal processing circuit (not shown) that processes the imaging signal output from the image sensor to generate an image; and a recording medium (not shown) for recording the generated image. The camera 400 can take still images or videos by pressing the shutter button 42, and the image data obtained from this shooting is recorded on the recording medium.

[0222] Although the technology of this disclosure has been described above with reference to embodiments and examples, the technology of this disclosure is not limited to the above embodiments and examples, and various modifications are possible. 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 each of the above embodiments, but can take other values.

[0223] Furthermore, the projection display device relating to the technology disclosed herein is not limited to the above configuration, and for example, the optical elements used for light beam separation or light beam combination, and the light bulb can be modified in various ways. The light bulb is not limited to a configuration in which light from a light source is spatially modulated by an image display element and output as an optical image based on image data, but may also be configured to output the light itself emitted from a self-emissive image display element as an optical image based on image data. Examples of self-emissive image display elements include image display elements in which light-emitting elements such as LEDs (Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes) are arranged in a two-dimensional array.

[0224] Furthermore, the imaging device relating to the technology disclosed herein is not limited to the configuration described above, and can take various forms, such as cameras other than mirrorless cameras, film cameras, video cameras, and cameras for filmmaking.

[0225] The following additional information is disclosed with respect to the above embodiments and examples. [Additional note 1] An imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image, and re-imaging the intermediate image as an enlarged image on an enlargement conjugate plane, The optical element positioned at the most magnified end is a lens. A first adjustment group moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the furthest point from the optical axis, The system includes a second adjustment group that moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the nearest point from the optical axis, The second adjustment group comprises at least two lenses, has a positive refractive power as a whole, and is positioned on the most retractable side, forming an imaging optical system. [Additional note 2] The second adjustment group consists of two lenses, At least one of the two lenses is a positive lens, If the Abbe number of the positive lens with respect to the d line is νp, νp<45 (1) An imaging optical system according to Appendix 1 that satisfies the conditional expression (1) represented by . [Additional note 3] Let the focal length of the first adjustment group be f1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined focal length of the multiple groups of the first adjustment group is set to f1. Let the focal length of the second adjustment group be f2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, and the combined focal length of the multiple groups in the second adjustment group is f2, 0.5 < |f1 / f2| < 30 (2) An imaging optical system according to appendix 1 or 2 that satisfies the conditional expression (2) represented by . [Additional note 4] Let the paraxial lateral magnification of the first adjustment group be β1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined paraxial transverse magnification of the multiple groups of the first adjustment group is set to β1. The combined paraxial transverse magnification of all optical systems on the reduction side of the first adjustment group is set to β1r. The paraxial lateral magnification of the second adjustment group is set to β2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, and the combined paraxial transverse magnification of the multiple groups in the second adjustment group is β2, 0<|{(1-β1 2 )×β1r 2} / (1-β2 2 )|<0.5 (3) An imaging optical system according to any one of the appendix items 1 to 3 that satisfies the conditional expression (3) represented by . [Additional note 5] The imaging optical system according to any one of the appendices 1 to 4, wherein the first adjustment group is positioned on the magnified side of the intermediate image. [Additional note 6] The imaging optical system consists of a first optical system and a second optical system, arranged in order from the magnification side to the reduction side, with the intermediate image in between. Let the focal length of the first optical system be fU1. Let fw be the focal length of the imaging optical system. When fU1 and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 1 <fU1 / |fw|<5 (4) An imaging optical system according to any one of the appendix items 1 to 5 that satisfies the conditional expression (4) represented by . [Additional note 7] Let Bfw be the back focus of the imaging optical system at the air-equivalent distance. Let fw be the focal length of the imaging optical system. When Bfw and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 3.5 <Bfw / |fw| (5) An imaging optical system according to any one of the appendix items 1 to 6 that satisfies the conditional expression (5) represented by . [Additional note 8] An imaging optical system according to any one of the appendices 1 to 7, comprising three single lenses having negative refractive power arranged in sequence from the most magnified to the least magnified. [Additional note 9] The aforementioned imaging optical system is a variable magnification optical system, The imaging optical system according to any one of the appendices 1 to 8, which includes at least two lens groups on the reduction side from the aforementioned intermediate image, the spacing between adjacent groups changes when the magnification is varied. [Additional Note 10] The first adjustment group is an imaging optical system according to any one of the appendices 1 to 9, comprising two or fewer lenses. [Additional Note 11] An imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image, and re-imaging the intermediate image as an enlarged image on an enlargement conjugate plane, The optical element positioned at the most magnified end is a lens. A first adjustment group moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the furthest point from the optical axis, The system includes a second adjustment group that moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the nearest point from the optical axis, The second adjustment group includes at least one positive lens, has a positive refractive power as a whole, and is positioned on the most retracted side. If the Abbe number of the positive lens with respect to the d line is νp, νp<45 (1) An imaging optical system that satisfies the condition (1) represented by . [Additional Note 12] Let the focal length of the first adjustment group be f1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined focal length of the multiple groups of the first adjustment group is set to f1. Let the focal length of the second adjustment group be f2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, and the combined focal length of the multiple groups in the second adjustment group is f2, 0.5 < |f1 / f2| < 30 (2) An imaging optical system according to appendix 11 that satisfies the conditional expression (2) represented by . [Additional Note 13] Let the paraxial lateral magnification of the first adjustment group be β1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined paraxial transverse magnification of the multiple groups of the first adjustment group is set to β1. The combined paraxial transverse magnification of all optical systems on the reduction side of the first adjustment group is set to β1r. The paraxial lateral magnification of the second adjustment group is set to β2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, and the combined paraxial transverse magnification of the multiple groups in the second adjustment group is β2, 0<|{(1-β1 2 )×β1r 2} / (1-β2 2 )|<0.5 (3) An imaging optical system according to appendix 11 or 12 that satisfies the conditional expression (3) represented by . [Additional Note 14] The imaging optical system according to any one of the appendices 11 to 13, wherein the first adjustment group is located on the magnified side of the intermediate image. [Additional Note 15] The imaging optical system consists of a first optical system and a second optical system, arranged in order from the magnification side to the reduction side, with the intermediate image in between. Let the focal length of the first optical system be fU1. Let fw be the focal length of the imaging optical system. When fU1 and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 1 <fU1 / |fw|<5 (4) An imaging optical system according to any one of the appendices 11 to 14 that satisfies the conditional expression (4) represented by . [Additional Note 16] Let Bfw be the back focus of the imaging optical system at the air-equivalent distance. Let fw be the focal length of the imaging optical system. When Bfw and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 3.5 <Bfw / |fw| (5) An imaging optical system according to any one of the appendices 11 to 15 that satisfies the conditional expression (5) represented by . [Additional Note 17] An imaging optical system according to any one of the appendices 11 to 16, comprising three single lenses having negative refractive power arranged in sequence from the most magnified to the least magnified. [Additional Note 18] The aforementioned imaging optical system is a variable magnification optical system, The imaging optical system according to any one of appendices 11 to 17, which includes at least two lens groups on the reduction side from the intermediate image, the spacing between adjacent groups changes when the magnification is changed. [Additional Note 19] The first adjustment group is an imaging optical system according to any one of the appendices 11 to 18, comprising two or fewer lenses. [Additional Note 20] A light bulb that outputs an optical image, The imaging optical system is as described in any one of the appendices 1 to 19, The imaging optical system is a projection-type display device that projects the optical image output from the light bulb onto a screen. [Additional Note 21] An imaging device equipped with an imaging optical system as described in any one of the appendices 1 to 19. [Explanation of Symbols]

[0226] 5 screens 6 screens 10. Imaging optical system 11a~11c Transmissive display elements 12 Dichroic Mirrors 13 Dichroic Mirror 14 Cross Dichroic Prism 15 light source 16a~16c condenser lens 18a~18c Total Internal Reflection Mirrors 21a~21c DMD elements 24a~24c TIR prism 25 Polarization Separation Prism 31a~31c Reflective display element 32 Dichroic Mirrors 33 Dichroic Mirror 34 Cross Dichroic Prism 35a~35c Polarization Separation Prism 38 Total Reflection Mirror 41 Camera Body 42 Shutter button 43 Power button 44 Control section 45 Operation section 46 Display section 47 Mount 48 interchangeable lenses 49 Imaging Optical System 100 Projection-type display devices 105 screens 200 Projection-type display devices 205 screens 210 Imaging Optical System 215 Light source 300 Projection Display Devices 305 screens 310 Imaging Optical System 315 Light source 400 Cameras A1 1st adjustment group A1a subgroup A1b subgroup A2 2nd adjustment group K0 Minimum angle of view light beam K1 Maximum half-angle light beam L1~L3 Lenses MI intermediate image Mr1 Miller Mr2 Miller PP optical components Pr prism Re1 1st area Re2 2nd area Sim Image Display Surface St aperture diaphragm U1 1st optical system U2 2nd optical system Va lens group Vb lens group Vc lens group Vd lens group Z optical axis

Claims

1. An imaging optical system capable of imaging an image on a reducing conjugate plane as an intermediate image, and re-imaging the intermediate image as an enlarged image on an enlargement conjugate plane, The optical element positioned at the most magnified end is a lens. A first adjustment group moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the furthest point from the optical axis, The system includes a second adjustment group that moves along the optical axis when adjusting the imaging position of the region in the magnified image that includes the nearest point from the optical axis, The second adjustment group consists of two lenses, has a positive refractive power as a whole, and is positioned on the most reducing side. Of the two lenses in the second adjustment group, at least one is a positive lens. If the Abbe number of the positive lens with respect to the d line is denoted by νp, νp < 45 (1) An imaging optical system that satisfies the condition (1) represented by .

2. Let the focal length of the first adjustment group be f1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined focal length of the multiple groups of the first adjustment group is set to f1. Let the focal length of the second adjustment group be f2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, and the combined focal length of the multiple groups of the second adjustment group is f2, 0.5<|f1 / f2|<30 (2) The imaging optical system according to claim 1 that satisfies the conditional expression (2) represented by .

3. The paraxial lateral magnification of the first adjustment group is set to β1. If the first adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, the combined paraxial transverse magnification of the multiple groups of the first adjustment group is set to β1. The combined paraxial transverse magnification of all optical systems on the reduction side of the first adjustment group is set to β1r. The paraxial lateral magnification of the second adjustment group is set to β2. If the second adjustment group consists of multiple groups that move while changing the distance between them and adjacent groups during the adjustment, then when the combined paraxial transverse magnification of the multiple groups of the second adjustment group is β2, 0<|{(1-β1 ２ )×β1r ２ } / (1-β2) ２ )|<0.5 (3) The imaging optical system according to claim 1 that satisfies the conditional expression (3) represented by .

4. The imaging optical system according to claim 1, wherein the first adjustment group is arranged on the magnified side of the intermediate image.

5. The imaging optical system consists of a first optical system and a second optical system, arranged in order from the magnification side to the reduction side, with the intermediate image in between. Let the focal length of the first optical system be fU1. Let the focal length of the imaging optical system be fw. When fU1 and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 1<fU1 / |fw|<5 (4) The imaging optical system according to claim 1 that satisfies the conditional expression (4) represented by .

6. Let Bfw be the back focus of the imaging optical system at the air equivalent distance. Let the focal length of the imaging optical system be fw. When Bfw and fw are taken as the values ​​at the wide-angle end in the case of the imaging optical system being a variable magnification optical system, 3.5<Bfw / |fw| (5) The imaging optical system according to claim 1 that satisfies the conditional expression (5) represented by .

7. The imaging optical system according to claim 1, comprising three single lenses having negative refractive power, arranged in sequence from the most magnified to the least magnified.

8. The aforementioned imaging optical system is a variable magnification optical system, The imaging optical system according to claim 1, which includes at least two lens groups on the reduction side of the intermediate image, wherein the spacing between adjacent groups changes when the image is magnified.

9. The imaging optical system according to claim 1, wherein the first adjustment group comprises two or fewer lenses.

10. A light bulb that outputs an optical image, The imaging optical system is as described in any one of claims 1 to 9, The imaging optical system is a projection-type display device that projects the optical image output from the light bulb onto a screen.

11. An imaging apparatus comprising an imaging optical system according to any one of claims 1 to 9.

Images