Zoom lens, projecting display device, and imaging device

Abstract

To provide a zoom lens which forms an intermediate image and which maintains excellent optical performance while having high magnification, a projecting display device including the zoom lens, and an imaging device including the zoom lens.SOLUTION: A zoom lens includes a first optical system and a second optical system in order from a magnification side to a reduction side. The second optical system forms an intermediate image at a position conjugate with a reduction-side image forming surface. The first optical system re-forms the intermediate image on a magnification-side image forming surface. A lens closest to the magnification side in the second optical system is a positive lens whose convex surface faces the magnification side. The second optical system includes first, second, and third moving lens groups which respectively move in order from the extreme magnification side to the reduction side in series during variation of its magnification. Only the first to third moving lens groups move during the variation of the magnification in the whole zoom lens.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology of the present disclosure relates to a zoom lens, a projection display device, and an imaging device.

Background Art

[0002] As a zoom lens applicable to a projection display device or an imaging device, an imaging optical system described in Patent Document 1 and Patent Document 2 below is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a zoom lens that forms an intermediate image, it is required to maintain good optical performance while having a high magnification. These required levels are increasing year by year.

[0005] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a zoom lens that maintains good optical performance while having a high magnification in a zoom lens that forms an intermediate image, a projection display device including this zoom lens, and an imaging device including this zoom lens.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a zoom lens including a first optical system and a second optical system in order along the optical path from the wide-angle side to the telephoto side. The second optical system forms an intermediate image at a position conjugate to the telephoto-side imaging surface, and the first optical system re-images the intermediate image onto the wide-angle-side imaging surface. The lens on the most wide-angle side of the second optical system is a positive lens with a convex surface facing the wide-angle side. When a group whose axial distance from an adjacent group changes during zooming is regarded as one lens group, the second optical system includes, in order along the optical path from the most wide-angle side to the telephoto side, a first moving lens group having a positive refractive power that moves during zooming, a second moving lens group that moves during zooming, and a third moving lens group having a positive refractive power that moves during zooming. Among the entire zoom lens, the lens groups that move during zooming are only the first moving lens group, the second moving lens group, and the third moving lens group.

[0007] In the zoom lens of the above aspect, it is preferable that the second optical system includes a fixed lens group that is fixed with respect to the telephoto-side imaging surface during zooming on the most telephoto side.

[0008] In the zoom lens of the above aspect, it is preferable that the fixed lens group has a positive refractive power.

[0009] In the zoom lens of the above aspect, it is preferable that the telephoto side is configured to be telecentric.

[0010] In the zoom lens of the above aspect, it is preferable that the second moving lens group has a negative refractive power.

[0011] When the focal length of the zoom lens at the wide-angle end is fw and the focal length of the first optical system is fr1, the zoom lens of the above aspect preferably satisfies the conditional expression (1) represented by: 0.8 < fr1 / |fw| < 5 (1)

[0012] In the zoom lens of the above aspect, it is preferable that the first optical system includes a cemented lens in which a positive lens, a negative lens, and a positive lens are cemented in order.

[0013] In the zoom lens of the above aspect, it is preferable that the effective diameter of the magnifying-side surface of the second lens from the magnifying side of the first optical system at the wide-angle end is smaller than the effective diameter of the magnifying-side surface of the most reduced-side lens of the first optical system at the wide-angle end.

[0014] In the zoom lens of the above aspect, it is preferable that the second moving lens group consists of one negative lens and one positive lens.

[0015] When the focal length of the first moving lens group is f1, the focal length of the second moving lens group is f2, and the focal length of the third moving lens group is f3, the zoom lens of the above aspect is 0 < |f1 / f2| < 0.75 (2) 0 < |f3 / f2| < 0.75 (3) and preferably satisfies the conditional expressions (2) and (3) represented by 0 < |f1 / f2| < 0.5 (2-2) 0 < |f3 / f2| < 0.5 (3-2) and more preferably satisfies the conditional expressions (2-2) and (3-2) represented by

[0016] When the focal length of the first moving lens group is f1 and the focal length of the third moving lens group is f3, the zoom lens of the above aspect is 0.5 < f1 / f3 < 2 (4) and preferably satisfies the conditional expression (4) represented by

[0017] In the zoom lens of the above aspect, at the telephoto end, the first moving lens group is located on the magnifying side with respect to the first moving lens group at the wide-angle end, the second moving lens group at the telephoto end is located on the magnifying side with respect to the second moving lens group at the wide-angle end, and the third moving lens group at the telephoto end is located on the magnifying side with respect to the third moving lens group at the wide-angle end.

[0018] In the zoom lens of the above aspect, when zooming from the wide-angle end to the telephoto end, it is preferable that the first moving lens group, the second moving lens group, and the third moving lens group always move toward the magnifying side.

[0019] In the zoom lens of the above aspect, it is preferable that a first optical path bending member for bending the optical path is disposed within the first optical system.

[0020] In the zoom lens of the above aspect, it is preferable that a second optical path bending member for bending the optical path is disposed on the reduction side with respect to the first optical system.

[0021] In the zoom lens of the above aspect, it is preferable that a first optical path bending member for bending the optical path is disposed within the first optical system, and a second optical path bending member for bending the optical path is disposed on the reduction side with respect to the first optical system.

[0022] In the zoom lens of the above aspect, the first optical system has a positive refractive power and is fixed with respect to the reduction-side imaging surface during zooming, and the second optical system includes, in order along the optical path from the enlargement side to the reduction side, a first moving lens group, a second moving lens group, a third moving lens group, and a fixed lens group fixed with respect to the reduction-side imaging surface during zooming.

[0023] Another aspect of the present disclosure is a projection display device including the zoom lens of the above aspect.

[0024] Still another aspect of the present disclosure is an imaging device including the zoom lens of the above aspect.

[0025] Note that the "comprising" and "consisting of" in this specification are intended to include, in addition to the recited components, lenses having substantially no 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.

[0026] The expressions "group having a positive refractive power" and "the group has a positive refractive power" in this specification mean that the entire group has a positive refractive power. Similarly, "group having a negative refractive power" and "the group has a negative refractive power" mean that the entire group has a negative refractive power. The "~ lens group" is not limited to a configuration composed of a plurality of lenses, and may be a configuration composed of only one lens.

[0027] The number of lenses described above is the number of lenses as components. For example, in a cemented lens in which a plurality of single lenses made of different materials are cemented together, the number of lenses is represented by the number of single lenses constituting this cemented lens. However, a compound aspherical lens (a lens in which a lens (for example, a spherical lens) and an aspherical film formed on the lens are integrally formed and function as one aspherical lens as a whole) is not regarded as a cemented lens and is treated as one lens. Unless otherwise specified, the sign of the refractive power and the surface shape of a lens including an aspherical surface are those in the paraxial region.

[0028] The "focal length" used in the conditional expression is the paraxial focal length. The values used in the conditional expression are values based on the d-line. The "d-line", "C-line", and "F-line" described in this specification are spectral lines, and the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line is treated as 656.27 nm (nanometers), and the wavelength of the F-line is treated as 486.13 nm (nanometers).

Advantages of the Invention

[0029] According to the present disclosure, it is possible to provide a zoom lens that forms an intermediate image and retains good optical performance while having a high magnification, a projection display device including this zoom lens, and an imaging device including this zoom lens.

Brief Description of the Drawings

[0030]

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Mode for Carrying Out the Invention

[0031] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0032] FIG. 1 shows a cross-sectional view of the configuration and light beam at the wide-angle end of a zoom lens according to an embodiment of the present disclosure. In FIG. 1, as the light beams, an on-axis light beam Ka and a light beam Kb with the maximum picture angle are shown. FIG. 2 shows a cross-sectional view of the configuration and light beam in each zoom state of this zoom lens. In FIG. 2, the upper stage marked with "wide-angle end" shows the wide-angle end state, the middle stage marked with "intermediate" shows the intermediate focal length state, and the lower stage marked with "telephoto end" shows the telephoto end state. The examples shown in FIGS. 1 and 2 correspond to the zoom lens of Example 1 described later. In FIGS. 1 and 2, the left side is the magnifying side and the right side is the reducing side. Hereinafter, the description will mainly be made with reference to FIG. 1.

[0033] The zoom lens of the present disclosure can be a projection optical system that is mounted on a projection display device to form an image projected onto a screen, and can also be an imaging optical system that is mounted on an imaging device to form an image of an object. Hereinafter, the case where the zoom lens is used for the purpose of a projection optical system will be assumed for description. Also, hereinafter, in order to avoid redundant description, "the zoom lens of the present disclosure" may be simply referred to as "the zoom lens".

[0034] In FIG. 1, assuming that a zoom lens is mounted on a projection display device, an example is shown in which an optical member PP and an image display surface Sim of a light valve are arranged on the reduction side of the zoom lens. The optical member PP is a member assuming a filter, a cover glass, a color combining prism, etc. The optical member PP is a member having no refractive power, and a configuration in which the optical member PP is omitted is also possible. The light valve outputs an optical image, and this optical image is displayed as an image on the image display surface Sim.

[0035] In a projection display device, a light beam given image information at the image display surface Sim is incident on the zoom lens through the optical member PP, and is projected by the zoom lens onto a screen (not shown). In this case, the image display surface Sim corresponds to the reduction-side imaging surface, and the screen corresponds to the enlargement-side imaging surface. Note that in this specification, "screen" means an object onto which a projection image formed by the zoom lens is projected. As the screen, in addition to a dedicated screen, a wall surface of a room, a floor surface, a ceiling, an outer wall of a building, etc. may be used.

[0036] Also, in the description of this specification, "enlargement side" means the screen side on the optical path, and "reduction side" means the image display surface Sim side on the optical path. In this specification, "enlargement side" and "reduction side" are determined along the optical path, and this is the same even in the case of a zoom lens forming a bent optical path. "The most enlarged side of ~" means the most enlarged side in the order on the optical path, and does not mean the closest to the screen in terms of distance. Hereinafter, in order to avoid making the description redundant, "in order along the optical path from the enlargement side to the reduction side" may be described as "in order from the enlargement side to the reduction side".

[0037] The zoom lens of the present disclosure includes a first optical system U1 and a second optical system U2 in order along the optical path from the telephoto side to the wide-angle side. The zoom lens of the present disclosure is configured such that the second optical system U2 forms an intermediate image MI at a position conjugate to the wide-angle side imaging surface, and the first optical system U1 re-images the intermediate image MI onto the telephoto side imaging surface. Hereinafter, among the optical systems constituting the zoom lens, the optical system on the telephoto side of the intermediate image MI is defined as the first optical system U1, and the optical system on the wide-angle side of the intermediate image MI is defined as the second optical system U2.

[0038] In the projection display device, the second optical system U2 forms an intermediate image MI of the image displayed on the image display surface Sim, and the first optical system projects this intermediate image MI onto the screen to form a projection image. In this way, by configuring the zoom lens of the present disclosure to have the intermediate image MI, it is possible to suppress the size of the lens system while realizing a wide-angle projection optical system. In FIG. 1, only the portion of the intermediate image MI below the optical axis Z is schematically shown by a dotted line. The intermediate image MI in FIG. 1 shows the position in the optical axis direction and does not show the exact shape.

[0039] The lens on the most telephoto side of the second optical system U2 is a positive lens with a convex surface facing the telephoto side. The lens on the most telephoto side of the second optical system U2 is, that is, the lens adjacent to the wide-angle side of the intermediate image MI. By making this lens a positive lens with a convex surface facing the telephoto side, even if the distance between the two lens surfaces sandwiching the intermediate image MI is increased, it is advantageous for reducing the diameter of the zoom lens.

[0040] The second optical system U2 includes, in order along the optical path from the most telephoto side to the wide-angle side, a first moving lens group having a positive refractive power that moves during zooming, a second moving lens group that moves during zooming, and a third moving lens group having a positive refractive power that moves during zooming. By including three lens groups that move during zooming in the second optical system U2, it is advantageous for obtaining a high zoom ratio. Since the second optical system U2 forms the intermediate image MI, the signs of the refractive powers of the first moving lens group and the third moving lens group are positive.

[0041] Among the entire zoom lens, the lens groups that move during zooming are only the first moving lens group, the second moving lens group, and the third moving lens group. By having only three lens groups that move during zooming in the entire zoom lens, it is possible to avoid complication of the zoom mechanism. Further, by arranging the three lens groups that move during zooming in sequence continuously along the optical path, it is advantageous for shortening the overall optical length.

[0042] In addition, in this specification, a group whose interval in the optical axis direction with an adjacent group changes during zooming is regarded as one lens group. That is, the "lens group" in this specification is a component of the zoom lens, and is a part including at least one lens separated by an air interval that changes during zooming. During zooming, each lens group moves or is fixed in units of lens groups, and the mutual interval of the lenses within each lens group does not change. Note that the "lens group" may include components other than lenses having no refractive power, such as diaphragms, masks, filters, cover glasses, plane mirrors, and prisms.

[0043] As an example, the zoom lens of FIG. 1 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order along the optical path from the wide-angle side to the telephoto side. The first optical system U1 is composed of lenses L1 to L13 in order from the wide-angle side to the telephoto side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the wide-angle side to the telephoto side.

[0044] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the interval with an adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the telephoto-side imaging surface. In FIG. 1, below the lens groups that move during zooming, the schematic movement trajectories of each lens group during zooming from the wide-angle end to the telephoto end are indicated by solid arrows.

[0045] As an example, each lens group in FIG. 1 is configured as follows. The first lens group G1 consists of a single lens, lens L21. The second lens group G2 consists of two lenses, lenses L22 to L23, and an aperture stop St, in order from the wide-angle side to the telephoto side. The third lens group G3 consists of six lenses, lenses L24 to L29, in order from the wide-angle side to the telephoto side. The fourth lens group G4 consists of a single lens, lens L30.

[0046] The zoom lens of FIG. 1 includes a focus group Gf as a group that moves along the optical axis Z during focusing. As an example, the focus group Gf in the example of FIG. 1 consists of two lenses, lenses L4 to L5. In FIG. 1, the symbol Gf below lenses L4 to L5 and the double-headed arrow in the horizontal direction indicate that lenses L4 to L5 are the focus group Gf.

[0047] The second optical system U2 preferably includes a fixed lens group that is fixed with respect to the telephoto-side imaging surface during zooming, on the most telephoto side. For example, as in the example of FIG. 1, the second optical system U2 may be configured to consist of, in order along the optical path from the wide-angle side to the telephoto side, a first moving lens group, a second moving lens group, a third moving lens group, and a fixed lens group. By fixing the lens group on the most telephoto side during zooming, it becomes easy to ensure telecentricity on the telephoto side while maintaining a high zoom ratio.

[0048] The fixed lens group included in the second optical system U2 preferably has a positive refractive power. In this case, it becomes easy to suppress the increase in diameter of the third moving lens group disposed on the wide-angle side of the fixed lens group.

[0049] The first optical system U1 may have a positive refractive power and may be configured to be fixed with respect to the telephoto-side imaging surface during zooming. In this case, it is advantageous for miniaturization of the lens system and simplification of the zoom mechanism.

[0050] The zoom lens of the present disclosure is preferably configured such that the reduction side is telecentric. In this case, when realizing a function of adjusting the position of the projection image on the screen by shifting the projection optical system in a direction perpendicular to the optical axis with respect to the image display element, that is, a so-called lens shift function, it is advantageous for securing the shift amount. In an optical system in which the reduction side is strictly configured to be telecentric, the chief ray from the most reduction-side surface of the optical system toward the reduction-side imaging surface is parallel to the optical axis Z.

[0051] However, "the reduction side is telecentric" in the technology of the present disclosure is not limited to the case where the angle of the chief ray with respect to the optical axis Z is 0 degree, and includes errors practically acceptable in the technical field to which the technology of the present disclosure belongs. The error may be, for example, in the range where the angle of the chief ray with respect to the optical axis Z is -3 degrees or more and +3 degrees or less. In a system that does not include an aperture stop, when viewing the light beam in the direction from the enlargement side to the reduction side, in the cross section of the light beam converging at an arbitrary point on the image display surface Sim, which is the reduction-side imaging surface, the bisector of the upper maximum ray and the lower maximum ray may be used as a substitute for the chief ray to determine the telecentricity.

[0052] The second moving lens group preferably has a negative refractive power. In this case, it is advantageous for suppressing fluctuations in various aberrations associated with zooming.

[0053] The second moving lens group preferably consists of one negative lens and one positive lens. In this case, it is advantageous for suppressing the occurrence of field curvature and chromatic aberration.

[0054] The first optical system U1 preferably includes a cemented lens in which a positive lens, a negative lens, and a positive lens are cemented in this order. In this case, it is advantageous for correcting chromatic aberration.

[0055] It is preferable that the effective diameter of the enlarged-side surface of the second lens from the enlarged side of the first optical system U1 at the wide-angle end is smaller than the effective diameter of the enlarged-side surface of the most reduced-side lens of the first optical system U1 at the wide-angle end. Generally, when attempting to achieve wide-angle conversion in a zoom lens that forms an intermediate image, it is likely to cause an increase in the diameter of the lens on the enlarged side. However, in the case of the above configuration, an increase in the diameter of the lens on the enlarged side can be suppressed, which is advantageous for weight reduction. By reducing the weight of the zoom lens, for example, when mounting the zoom lens on a projection display device having a lens shift function, the burden on the shift mechanism can be reduced.

[0056] In this specification, for the light rays that enter the lens surface from the enlarged side and are emitted from the reduced side, twice the distance from the intersection of the outermost light ray passing through the lens surface and the lens surface to the optical axis Z is defined as the "effective diameter" of the lens surface. The "outer side" mentioned here refers to the radially outer side centered on the optical axis Z, that is, the side away from the optical axis Z.

[0057] In the zoom lens of the present disclosure, it is preferable that the first moving lens group at the telephoto end is located on the enlarged side relative to the first moving lens group at the wide-angle end. Similarly, it is preferable that the second moving lens group at the telephoto end is located on the enlarged side relative to the second moving lens group at the wide-angle end. Similarly, it is preferable that the third moving lens group at the telephoto end is located on the enlarged side relative to the third moving lens group at the wide-angle end. In this case, it is advantageous for simplifying the drive mechanism.

[0058] Also, in the zoom lens of the present disclosure, when zooming from the wide-angle end to the telephoto end, it is more preferable that the first moving lens group, the second moving lens group, and the third moving lens group all move toward the enlarged side. In this case, it is more advantageous by simplifying the drive mechanism.

[0059] In the zoom lens of the present disclosure, a first optical path bending member that bends the optical path may be arranged inside the first optical system U1. By bending the optical path, a compact configuration becomes possible, which is advantageous for miniaturization. When a zoom lens having a configuration in which the optical path is bent once is mounted on a projection display device, it is conceivable to accommodate the portion on the reduction side of the bending portion in the housing of the device main body, and to accommodate the portion on the enlargement side of the bending portion in a protruding portion protruding from the housing. In this case, by arranging the optical path bending member inside the first optical system U1 on the enlargement side, the length from the lens on the most enlarged side to the bending portion can be shortened, which is advantageous for miniaturization of the protruding portion. Further, by rotating the bending portion, the lens on the most enlarged side can be positioned in an arbitrary direction, so that projection in various directions becomes possible. As the first optical path bending member, for example, a prism having a reflecting surface, a mirror, or the like can be used.

[0060] As a first modification example of the zoom lens of FIG. 1, FIG. 3 shows an example of a zoom lens having a first optical path bending member. The zoom lens of FIG. 3 includes a first optical system U1r and a second optical system U2 in order along the optical path from the enlargement side to the reduction side. The zoom lens of FIG. 3 is different from the zoom lens of FIG. 1 in that a mirror R1 is arranged inside the first optical system U1r and the optical path is bent by the mirror R1, and the configurations of the other lenses are the same as those in the example of FIG. 1. The mirror R1 corresponds to the first optical path bending member of the present disclosure. FIG. 3 shows the configuration at the wide-angle end, and illustration of the lens reference numerals is partially omitted to avoid complication of the drawing.

[0061] In the zoom lens of the present disclosure, a second optical path bending member that bends the optical path may be arranged on the reduction side of the first optical system U1. By bending the optical path, a compact configuration is possible, which is advantageous for miniaturization. An optical system having an intermediate image MI tends to have a long overall length, but by bending the optical path on the reduction side of the first optical system U1, it is possible to suppress the optical system from becoming long in one direction. Further, by rotating the bending portion, the lens on the most enlarged side can be positioned in an arbitrary direction, so that it is possible to project in various directions. As the second optical path bending member, for example, a prism having a reflecting surface, a mirror, or the like can be used.

[0062] As a second modification example of the zoom lens of FIG. 1, FIG. 4 shows an example of a zoom lens having a second optical path bending member. The zoom lens of FIG. 4 includes a first optical system U1 and a second optical system U2r in order along the optical path from the enlarged side to the reduced side. The zoom lens of FIG. 4 is different from the zoom lens of FIG. 1 in that a mirror R2 is arranged on the most enlarged side of the second optical system U2r and the optical path is bent by the mirror R2, and the configurations of the other lenses are the same as those in the example of FIG. 1. The mirror R2 corresponds to the second optical path bending member of the present disclosure. FIG. 4 shows the configuration at the wide-angle end, and some of the lens reference numerals are omitted to avoid complication of the drawing.

[0063] In the zoom lens of the present disclosure, a first optical path bending member that bends the optical path may be arranged in the first optical system U1, and a second optical path bending member that bends the optical path may be arranged on the reduction side of the first optical system U1. By bending the optical path twice, a more compact configuration is possible, which is more advantageous for miniaturization. When a zoom lens having a configuration in which the optical path is bent twice is mounted on a projection display device, by rotating each of the two bending portions, the lens on the most enlarged side can be positioned in an arbitrary direction, so that it is possible to project in various directions.

[0064] As a third modification example of the zoom lens of FIG. 1, FIG. 5 shows an example of a zoom lens having two optical path bending members and bending the optical path twice. The zoom lens of FIG. 5 is composed of a first optical system U1r and a second optical system U2r in order along the optical path from the wide-angle side to the telephoto side. The first optical system U1r of FIG. 5 is the same as the first optical system U1r of FIG. 3, and the second optical system U2r of FIG. 5 is the same as the second optical system U2r of FIG. 4. Mirror R1 corresponds to the first optical path bending member of the present disclosure, and mirror R2 corresponds to the second optical path bending member of the present disclosure. FIG. 5 shows the configuration at the wide-angle end, and the illustration of the lens reference numerals is partially omitted to avoid complication of the drawing.

[0065] The angle for bending the optical path of the optical path bending member can be arbitrarily set, for example, it may be 90 degrees. By setting the bending angle to 90 degrees, a structure that is easy to manufacture can be obtained. Note that this "90 degrees" includes errors that are practically acceptable in the technical field to which the technology of the present disclosure belongs. The error may be, for example, ±5 degrees.

[0066] Next, a preferable configuration regarding the conditional expression of the zoom lens of the present disclosure will be described. In the following description of the conditional expression, in order to avoid redundant description, the same symbols are used for those with the same definition, and the duplicate description of the symbols is omitted.

[0067] When the focal length of the zoom lens at the wide-angle end is fw and the focal length of the first optical system U1 is fr1, it is preferable that the zoom lens satisfies the following conditional expression (1). Note that fw is the value in the state where the projection distance is 0.97 m (meter). The projection distance is the distance on the optical axis from the magnified-side imaging surface to the most magnified-side lens surface. By preventing the corresponding value of the conditional expression (1) from falling below the lower limit value, the refractive power of the first optical system U1 does not become too strong, which is advantageous for correcting various aberrations. By preventing the corresponding value of the conditional expression (1) from exceeding the upper limit value, the refractive power of the first optical system U1 does not become too weak, which is advantageous for wide-angle conversion. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (1-1), and it is even more preferable that the zoom lens satisfies the following conditional expression (1-2). 0.8 < fr1 / |fw| < 5 (1) 1 < fr1 / |fw| < 3 (1 - 1) 1.5 < fr1 / |fw| < 2.5 (1 - 2)

[0068] When the focal length of the first moving lens group is f1 and the focal length of the second moving lens group is f2, it is preferable that the zoom lens satisfies the following conditional expression (2). Regarding the lower limit of the conditional expression (2), since |f1 / f2| is an absolute value, 0 < |f1 / f2|. By ensuring that the corresponding value of the conditional expression (2) does not exceed the upper limit value, the refractive power of the second moving lens group does not become too strong, and the balance of the refractive powers of the first moving lens group and the second moving lens group can be maintained well. Therefore, it is advantageous for suppressing the occurrence of various aberrations. To obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (2 - 1), and it is even more preferable that the zoom lens satisfies the following conditional expression (2 - 2). 0 < |f1 / f2| < 0.75 (2) 0 < |f1 / f2| < 0.6 (2 - 1) 0 < |f1 / f2| < 0.5 (2 - 2)

[0069] When the focal length of the third moving lens group is f3, it is preferable that the zoom lens satisfies the following conditional expression (3). Regarding the lower limit of the conditional expression (3), since |f3 / f2| is an absolute value, 0 < |f3 / f2|. By ensuring that the corresponding value of the conditional expression (3) does not exceed the upper limit value, the refractive power of the second moving lens group does not become too strong, and the balance of the refractive powers of the second moving lens group and the third moving lens group can be maintained well. Therefore, it is advantageous for suppressing the occurrence of various aberrations. To obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (3 - 1), and it is even more preferable that the zoom lens satisfies the following conditional expression (3 - 2). 0 < |f3 / f2| < 0.75 (3) 0 < |f3 / f2| < 0.6 (3 - 1) 0 < |f3 / f2| < 0.5 (3 - 2)

[0070] The zoom lens preferably satisfies the following conditional expression (4). By preventing the corresponding value of the conditional expression (4) from falling below the lower limit value, the refractive power of the first moving lens group does not become too strong, which is advantageous for suppressing the occurrence of various aberrations associated with zooming. By preventing the corresponding value of the conditional expression (4) from exceeding the upper limit value, the refractive power of the third moving lens group does not become too strong, which is advantageous for suppressing the occurrence of various aberrations associated with zooming. In order to obtain better characteristics, it is more preferable for the zoom lens to satisfy the following conditional expression (4-1), and even more preferably to satisfy the following conditional expression (4-2). 0.5 < f1 / f3 < 2 (4) 0.6 < f1 / f3 < 1.67 (4-1) 0.7 < f1 / f3 < 1.43 (4-2)

[0071] The preferred configurations and possible configurations described above, including the configuration related to the conditional expression, can be combined arbitrarily, and it is preferable to selectively adopt them as appropriate according to the required specifications.

[0072] Next, examples and modifications of the zoom lens of the present disclosure will be described with reference to the drawings. Note that the reference numerals attached to the cross-sectional views of each example and modification are used independently for each example and modification in order to avoid complication of the description and drawings due to an increase in the number of digits of the reference numerals. Therefore, even if the same reference numeral is attached in the drawings of different examples and modifications, they are not necessarily the same configuration.

[0073] [Example 1] The configuration and cross-sectional view of the light beam of the zoom lens of Example 1 are shown in FIGS. 1 and 2, and the illustration method and configuration are as described above, so some duplicate descriptions will be omitted here.

[0074] The zoom lens of Example 1 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the telephoto side to the wide-angle side. The first optical system U1 is composed of lenses L1 to L13 in order from the telephoto side to the wide-angle side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the telephoto side to the wide-angle side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the telephoto side to the wide-angle side. The third lens group G3 is composed of lenses L24 to L29 in order from the telephoto side to the wide-angle side. The fourth lens group G4 is composed of a lens L30.

[0075] During variable magnification, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the interval from the adjacent group. During variable magnification, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the image plane on the wide-angle side. The focus group Gf is composed of lenses L4 to L5.

[0076] For the zoom lens of Example 1, the basic lens data are shown in Tables 1A and 1B, the specifications and variable surface intervals are shown in Table 2, and the aspherical coefficients are shown in Table 3. Here, in order to avoid making one table too long, the basic lens data are shown in two tables, Table 1A and Table 1B. Table 1A shows the first optical system U1, and Table 1B shows the second optical system U2 and the optical member PP.

[0077] The table of the basic lens data is described as follows. In the column of "Sn", the surface number is shown when the surface on the most telephoto side is taken as the first surface and the numbers are increased one by one toward the wide-angle side. In the column of "R", the radius of curvature of each surface is shown. In the column of "D", the surface interval on the optical axis between each surface and the surface adjacent to it on the wide-angle side is shown. In the column of "Nd", the refractive index with respect to the d-line of each component is shown. In the column of "νd", the Abbe number based on the d-line of each component is shown. In the column of "ED", the effective diameter in terms of diameter is shown. ED shows only the surface on the wide-angle side of the second lens from the telephoto side of the first optical system U1 and the surface on the wide-angle side of the lens on the most wide-angle side of the first optical system U1, and the description of the column is omitted in Table 1B.

[0078] In the table of basic lens data, the sign of the radius of curvature of the surface facing the convex shape on the magnification side is positive, and the sign of the radius of curvature of the surface facing the convex shape on the reduction side is negative. In the column of the surface number corresponding to the aperture stop St, the phrases "surface number" and "(St)" are described. The value in the bottommost column of the D column in Table 1B is the distance between the surface on the most reduction side in the table and the image display surface Sim. In the table of basic lens data, for the variable surface interval during zooming, the symbol DD[ ] is used, and the surface number on the magnification side of this interval is attached in [ ] and entered in the D column.

[0079] Table 2 shows the zoom ratio Zr, the absolute value of the focal length |f|, the F-number FNo., the maximum total angle of view 2ω, and the variable surface interval based on the d line. The [°] in the column of 2ω indicates that the unit is degrees. The values shown in Table 1 and Table 2 are the values in the state where the projection distance is 0.97 m (meter). In Table 2, the values at the wide-angle end are shown in the "wide-angle end" column, the values in the intermediate focal length state are shown in the "intermediate" column, and the values at the telephoto end are shown in the "telephoto end" column.

[0080] In the basic lens data, an asterisk is attached to the surface number of the aspherical surface, and the value of the paraxial radius of curvature is described in the column of the radius of curvature of the aspherical surface. In Table 3, the row of Sn shows the surface number of the aspherical surface, and the rows of KA and Am (m = 3, 4, 5, ···, 20) show the numerical values of the aspherical coefficients for each aspherical surface. The "E±n" (n: integer) of the numerical values of the aspherical coefficients in Table 3 means "×10 ±n ". KA and Am are the aspherical coefficients in the aspherical formula represented by the following formula. Zd = C × h 2 / {1 + (1 - KA × C 2 × h 2 ) 1 / 2}+ ΣAm × h m However, Zd: Aspherical depth (the length of the perpendicular dropped from the point on the aspherical surface at height h to the plane perpendicular to the optical axis Z where the aspherical vertex touches) h: Height (the distance from the optical axis Z to the lens surface) C: Reciprocal of the paraxial radius of curvature KA, Am: Aspherical coefficients where the aspherical Σ means the sum with respect to m.

[0081] In the data of each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length. However, since the optical system can be used even with proportional magnification or reduction, other appropriate units can also be used. Also, in each of the tables shown below, the numerical values are rounded to a predetermined number of digits.

[0082]

Table 1A

[0083]

Table 1B

[0084]

Table 2

[0085]

Table 3

[0086] Fig. 6 shows aberration diagrams of the zoom lens of Example 1 in a state where the projection distance is 0.97 m (meter). In Fig. 6, from left to right, spherical aberration, astigmatism, distortion, and chromatic aberration of magnification are shown. In Fig. 6, the aberration diagrams at the wide-angle end are shown in the upper row labeled "wide-angle end", the aberration diagrams in the state of the intermediate focal length are shown in the middle row labeled "intermediate", and the aberration diagrams at the telephoto end are shown in the lower row labeled "telephoto end". In the spherical aberration diagram, the aberrations related to the d-line, C-line, and F-line are shown by solid line, long dashed line, and short dashed line, 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 of magnification diagram, the aberrations related to the C-line and F-line are shown by a long dashed line and a short dashed line, respectively. In the spherical aberration diagram, the value of the F-number is shown after "FNo.=". In the other aberration diagrams, the value of the maximum semi-aperture angle is shown after "ω=".

[0087] FIG. 3, FIG. 4, and FIG. 5 respectively show cross-sectional views of the configurations of the first modified example, the second modified example, and the third modified example of the zoom lens of Example 1. Since the configurations of the examples in FIGS. 3 to 5 are as described above, duplicate descriptions are omitted here.

[0088] The symbols, meanings, description methods, and illustration methods of the respective data regarding the above Example 1 and the modified examples are basically the same in the following examples unless otherwise specified, so duplicate descriptions are omitted below.

[0089] [Example 2] FIG. 7 shows a cross-sectional view of the configuration and light beam at the wide-angle end of the zoom lens of Example 2. The zoom lens of Example 2 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the magnification side to the reduction side. The first optical system U1 is composed of lenses L1 to L12 in order from the magnification side to the reduction side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the magnification side to the reduction side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the magnification side to the reduction side. The third lens group G3 is composed of lenses L24 to L29 in order from the magnification side to the reduction side. The fourth lens group G4 is composed of a lens L30.

[0090] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the interval from the adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the reduction-side imaging surface. The focus group Gf is composed of lenses L4 to L5.

[0091] Regarding the zoom lens of Example 2, the basic lens data is shown in Tables 4A and 4B, the specifications and variable surface intervals are shown in Table 5, the aspherical coefficients are shown in Table 6, and each aberration diagram is shown in FIG. 9. The basic lens data, specifications, and each aberration diagram are for a state where the projection distance is 0.97 m (meter).

[0092]

Table 4A

[0093]

Table 4B

[0094]

Table 5

[0095]

Table 6

[0096] FIG. 8 shows the configuration and light beam at the wide-angle end of the zoom lens which is a modification of Example 2. The zoom lens of FIG. 8 has two optical path bending members and bends the optical path twice. The zoom lens of FIG. 8 is composed of a first optical system U1r and a second optical system U2r in order along the optical path from the magnification side to the reduction side. In the first optical system U1r of FIG. 8, a mirror R1 is arranged inside the first optical system U1r, and the point where the optical path is bent by the mirror R1 is different from the first optical system U1 of Example 2. In the second optical system U2r of FIG. 8, a mirror R2 is arranged on the most magnified side of the second optical system U2r, and the point where the optical path is bent by the mirror R2 is different from the second optical system U2 of Example 2. Other configurations of the zoom lens of FIG. 8 are the same as those of the zoom lens of Example 2.

[0097] [Example 3] Fig. 10 shows the configuration and cross-sectional view of the light beam at the wide-angle end of the zoom lens of Example 3. The zoom lens of Example 3 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the magnification side to the reduction side. The first optical system U1 is composed of lenses L1 to L13 in order from the magnification side to the reduction side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the magnification side to the reduction side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the magnification side to the reduction side. The third lens group G3 is composed of lenses L24 to L29 in order from the magnification side to the reduction side. The fourth lens group G4 is composed of a lens L30.

[0098] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the distance from the adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the reduction-side imaging surface. The focus group Gf is composed of lenses L4 to L5.

[0099] For the zoom lens of Example 3, the basic lens data is shown in Tables 7A and 7B, the specifications and variable surface intervals are shown in Table 8, the aspherical coefficients are shown in Table 9, and each aberration diagram is shown in Fig. 12. The basic lens data, specifications, and each aberration diagram are those in a state where the projection distance is 0.97 m (meter).

[0100]

Table 7A

[0101]

Table 7B

[0102]

Table 8

[0103]

Table 9

[0104] FIG. 11 shows the configuration and light beam at the wide-angle end of the zoom lens which is a modification of Example 3. The zoom lens of FIG. 11 has two optical path bending members and bends the optical path twice. The zoom lens of FIG. 11 is composed of a first optical system U1r and a second optical system U2r in order along the optical path from the magnification side to the reduction side. In the first optical system U1r of FIG. 11, a mirror R1 is disposed inside the first optical system U1r, and the point where the optical path is bent by the mirror R1 is different from the first optical system U1 of Example 3. In the second optical system U2r of FIG. 11, a mirror R2 is disposed on the most magnification side of the second optical system U2r, and the point where the optical path is bent by the mirror R2 is different from the second optical system U2 of Example 3. Other configurations of the zoom lens of FIG. 11 are the same as those of the zoom lens of Example 3.

[0105] [Example 4] FIG. 13 shows a cross-sectional view of the configuration and light beam at the wide-angle end of the zoom lens of Example 4. The zoom lens of Example 4 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the magnification side to the reduction side. The first optical system U1 is composed of lenses L1 to L13 in order from the magnification side to the reduction side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the magnification side to the reduction side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the magnification side to the reduction side. The third lens group G3 is composed of lenses L24 to L29 in order from the magnification side to the reduction side. The fourth lens group G4 is composed of a lens L30.

[0106] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the interval from the adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the reduction-side imaging surface. The focus group Gf is composed of lenses L4 to L5.

[0107] For the zoom lens of Example 4, the basic lens data is shown in Tables 10A and 10B, the specifications and variable surface intervals are shown in Table 11, the aspherical coefficients are shown in Table 12, and each aberration diagram is shown in FIG. 15. The basic lens data, specifications, and each aberration diagram are for the state where the projection distance is 0.97 m (meter).

[0108]

Table 10A

[0109]

Table 10B

[0110]

Table 11

[0111]

Table 12

[0112] FIG. 14 shows the configuration and light beam at the wide-angle end of the zoom lens which is a modification of Example 4. The zoom lens of FIG. 14 has two optical path bending members and bends the optical path twice. The zoom lens of FIG. 14 consists of a first optical system U1r and a second optical system U2r in order along the optical path from the magnification side to the reduction side. In the first optical system U1r of FIG. 14, a mirror R1 is disposed inside the first optical system U1r, and the point where the optical path is bent by the mirror R1 is different from the first optical system U1 of Example 4. In the second optical system U2r of FIG. 14, a mirror R2 is disposed on the most magnification side of the second optical system U2r, and the point where the optical path is bent by the mirror R2 is different from the second optical system U2 of Example 4. Other configurations of the zoom lens of FIG. 14 are the same as those of the zoom lens of Example 4.

[0113] [Example 5] The configuration and cross-sectional view of the light beam at the wide-angle end of the zoom lens of Example 5 are shown in Fig. 16. The zoom lens of Example 5 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the magnification side to the reduction side. The first optical system U1 is composed of lenses L1 to L13 in order from the magnification side to the reduction side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the magnification side to the reduction side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the magnification side to the reduction side. The third lens group G3 is composed of lenses L24 to L29 in order from the magnification side to the reduction side. The fourth lens group G4 is composed of a lens L30.

[0114] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the distance from the adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the reduction-side imaging surface. The focus group Gf is composed of lenses L4 to L5.

[0115] Regarding the zoom lens of Example 5, the basic lens data is shown in Tables 13A and 13B, the specifications and variable surface intervals are shown in Table 14, the aspherical coefficients are shown in Table 15, and each aberration diagram is shown in Fig. 18. The basic lens data, specifications, and each aberration diagram are those in a state where the projection distance is 0.97 m (meter).

[0116]

Table 13A

[0117]

Table 13B

[0118]

Table 14

[0119]

Table 15

[0120] Fig. 17 shows the configuration and light beam at the wide-angle end of the zoom lens which is a modified example of Example 5. The zoom lens of Fig. 17 has two optical path bending members and bends the optical path twice. The zoom lens of Fig. 17 is composed of a first optical system U1r and a second optical system U2r in order along the optical path from the magnification side to the reduction side. In the first optical system U1r of Fig. 17, a mirror R1 is arranged inside the first optical system U1r, and the point where the optical path is bent by the mirror R1 is different from the first optical system U1 of Example 5. In the second optical system U2r of Fig. 17, a mirror R2 is arranged on the most magnification side of the second optical system U2r, and the point where the optical path is bent by the mirror R2 is different from the second optical system U2 of Example 5. Other configurations of the zoom lens of Fig. 17 are the same as those of the zoom lens of Example 5.

[0121] [Example 6] Fig. 19 shows the cross-sectional view of the configuration and light beam at the wide-angle end of the zoom lens of Example 6. The zoom lens of Example 6 is composed of a first optical system U1 having a positive refractive power and a second optical system U2 in order from the magnification side to the reduction side. The first optical system U1 is composed of lenses L1 to L14 in order from the magnification side to the reduction side. The second optical system U2 is composed of a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 in order from the magnification side to the reduction side. The first lens group G1 is composed of a lens L21. The second lens group G2 is composed of lenses L22 to L23 and an aperture stop St in order from the magnification side to the reduction side. The third lens group G3 is composed of lenses L24 to L30 in order from the magnification side to the reduction side. The fourth lens group G4 is composed of a lens L31.

[0122] During zooming, the first lens group G1, the second lens group G2, and the third lens group G3 each move along the optical axis Z by changing the interval from the adjacent group. During zooming, the first optical system U1 and the fourth lens group G4 are each fixed with respect to the reduction-side imaging surface. The focus group Gf is composed of lenses L4 to L5.

[0123] For the zoom lens of Example 6, the basic lens data are shown in Tables 16A and 16B, the specifications and variable surface intervals are shown in Table 17, the aspherical coefficients are shown in Table 18, and each aberration diagram is shown in FIG. 21. The basic lens data, specifications, and each aberration diagram are for a projection distance of 0.97 m (meter).

[0124]

Table 16A

[0125]

Table 16B

[0126]

Table 17

[0127]

Table 18

[0128] FIG. 20 shows the configuration and light beam at the wide-angle end of the zoom lens which is a modified example of Example 6. The zoom lens of FIG. 20 has two optical path bending members and bends the optical path twice. The zoom lens of FIG. 20 consists of a first optical system U1r and a second optical system U2r in order along the optical path from the magnification side to the reduction side. In the first optical system U1r of FIG. 20, a mirror R1 is arranged inside the first optical system U1r, and the point where the optical path is bent by the mirror R1 is different from the first optical system U1 of Example 6. In the second optical system U2r of FIG. 20, a mirror R2 is arranged on the most magnification side of the second optical system U2r, and the point where the optical path is bent by the mirror R2 is different from the second optical system U2 of Example 6. Other configurations of the zoom lens of FIG. 20 are the same as those of the zoom lens of Example 6.

[0129] In the above, for Examples 2 to 6, as a modification, an example in which the optical path is bent twice was shown. However, for Examples 2 to 6 as well, as a modification of the optical path bending member, a configuration having only the first optical path bending member and a configuration having only the second optical path bending member are possible.

[0130] Table 19 shows the corresponding values of conditional expressions (1) to (4) of the zoom lenses of Examples 1 to 6. The corresponding values of the examples shown in Table 19 may be used as the upper limit or the lower limit of the conditional expression to set the preferable range of the conditional expression.

[0131]

Table 19

[0132] The zoom lenses of Examples 1 to 6 have a zoom ratio of 1.2 times or more and have a high magnification. The zoom lenses of Examples 1 to 6 have an overall angle of view at the wide-angle end of 105 degrees or more and have a wide angle of view. Further, in the zoom lenses of Examples 1 to 6, the aberration variation during zooming is suppressed, and each aberration is well corrected to realize high optical performance.

[0133] Next, a projection display device according to an embodiment of the present disclosure will be described. FIG. 22 is a schematic configuration diagram of a projection display device according to an embodiment of the present disclosure. The projection display device 100 shown in FIG. 22 includes a zoom lens 10 according to an embodiment of the present disclosure, a light source 15, and transmissive display elements 11a to 11c as a light valve that outputs an optical image corresponding to each color light. The projection display device 100 also includes 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. In FIG. 22, the zoom lens 10 is schematically illustrated. An integrator is disposed between the light source 15 and the dichroic mirror 12, but its illustration is omitted in FIG. 22.

[0134] The white light from the light source 15 is decomposed into three color light beams (blue light, green light, and red light) by the dichroic mirrors 12 and 13, and then enters the transmissive display elements 11a to 11c corresponding to the respective color light beams through the condenser lenses 16a to 16c, is modulated, color-combined by the cross-dichroic prism 14, and then enters the zoom lens 10. The zoom lens 10 projects an optical image based on the modulated light modulated by the transmissive display elements 11a to 11c onto the screen 105.

[0135] FIG. 23 is a schematic configuration diagram of a projection display device according to another embodiment of the present disclosure. The projection display device 200 shown in FIG. 23 includes a zoom lens 210 according to the embodiment of the present disclosure, a light source 215, and DMD (Digital Micromirror Device: registered trademark) elements 21a to 21c as light valves that output optical images corresponding to respective color lights. Further, the projection display device 200 includes TIR (Total Internal Reflection) prisms 24a to 24c for color separation and color combination, and a polarization separation prism 25 for separating illumination light and projection light. Note that the zoom lens 210 is schematically illustrated in FIG. 23. An integrator is disposed between the light source 215 and the polarization separation prism 25, but its illustration is omitted in FIG. 23.

[0136] The white light from the light source 215 is reflected by the reflection 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. The decomposed color light beams respectively enter the corresponding DMD elements 21a to 21c, are modulated, travel in the reverse direction through the TIR prisms 24a to 24c again for color combination, pass through the polarization separation prism 25, and enter the zoom lens 210. The zoom lens 210 projects an optical image based on the modulated light modulated by the DMD elements 21a to 21c onto the screen 205.

[0137] FIG. 24 is a schematic configuration diagram of a projection display device according to still another embodiment of the present disclosure. The projection display device 300 shown in FIG. 24 includes a zoom lens 310 according to an embodiment of the present disclosure, a light source 315, and reflective display elements 31a to 31c as light valves that output optical images corresponding to respective color lights. 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. In FIG. 24, the zoom lens 310 is schematically illustrated. An integrator is disposed between the light source 315 and the dichroic mirror 32, but its illustration is omitted in FIG. 24.

[0138] The white light from the light source 315 is decomposed by the dichroic mirrors 32 and 33 into three color light beams (blue light, green light, and red light). Each of the decomposed color light beams passes through the polarization separation prisms 35a to 35c, is incident on the reflective display elements 31a to 31c corresponding to the respective color light beams, is modulated, is color-synthesized by the cross-dichroic prism 34, and then is incident on the zoom lens 310. The zoom lens 310 projects an optical image based on the modulated light modulated by the reflective display elements 31a to 31c onto the screen 305.

[0139] FIGS. 25 and 26 are external views of a camera 400 which is an imaging device according to an embodiment of the present disclosure. FIG. 25 shows a perspective view of the camera 400 as seen from the front side, and FIG. 26 shows a perspective view of the camera 400 as seen from the back side. The camera 400 is a mirrorless single-lens digital camera to which an interchangeable lens 48 is detachably attached. The interchangeable lens 48 houses a zoom lens 49 according to an embodiment of the present disclosure in a lens barrel.

[0140] The camera 400 includes a camera body 41, and a shutter button 42 and a power button 43 are provided on the upper surface of the camera body 41. Also, an operation unit 44, an operation unit 45, and a display unit 46 are provided on the back surface of the camera body 41. The display unit 46 displays the captured image and the image within the angle of view before being captured.

[0141] A shooting aperture through which light from the shooting object enters is provided at the central portion of the front surface of the camera body 41, and a mount 47 is provided at a position corresponding to the shooting aperture. An interchangeable lens 48 is attached to the camera body 41 via the mount 47.

[0142] An imaging device 50 is provided inside the camera body 41. The imaging device 50 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 48. As the imaging device 50, for example, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), or the like is used. A signal processing circuit (not shown), a recording medium (not shown), and the like are provided inside the camera body 41. The signal processing circuit processes the imaging signal output from the imaging device 50 to generate an image. The recording medium is for recording the generated image. In the camera 400, it is possible to shoot a still image or a moving image by pressing the shutter button 42, and the image data obtained by this shooting is recorded on the above recording medium.

[0143] As described above, the technology of the present disclosure has been described with reference to the embodiments and examples, but the technology of the present disclosure is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, the distance between surfaces, the refractive index, the Abbe number, the aspherical coefficient, etc. of each lens are not limited to the values shown in the above examples, and other values can be taken.

[0144] In addition, the projection display device according to the technology of the present disclosure is not limited to the above configuration. For example, the optical member and the light valve used for beam separation or beam combination can be changed in various ways. The light valve is not limited to the mode of spatially modulating the light from the light source by the image display element and outputting it as an optical image based on the image data. It may also be a mode of outputting the light itself output from the self-luminous image display element as an optical image based on the image data. Examples of the self-luminous image display element include an image display element in which light-emitting elements such as LEDs (Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes) are two-dimensionally arranged.

[0145] In addition, the imaging device according to the technology of the present disclosure is not limited to the above configuration. For example, it can be in various forms such as cameras other than the mirrorless type, film cameras, video cameras, security cameras, and movie cameras.

[0146] Regarding the above embodiments and examples, the following supplementary notes are further disclosed. [Supplementary Note 1] A zoom lens including a first optical system and a second optical system in order along the optical path from the wide-angle side to the telephoto side, The second optical system forms an intermediate image at a position conjugate to the telephoto-side imaging surface, and the first optical system re-images the intermediate image on the wide-angle-side imaging surface, The lens on the most wide-angle side of the second optical system is a positive lens with a convex surface facing the wide-angle side, When a group whose interval in the optical axis direction with an adjacent group changes during zooming is regarded as one lens group, The second optical system includes, in order along the optical path from the most wide-angle side to the telephoto side, a first moving lens group having a positive refractive power that moves during zooming, a second moving lens group that moves during zooming, and a third moving lens group having a positive refractive power that moves during zooming, Among the entire zoom lens, the lens groups that move during zooming are only the first moving lens group, the second moving lens group, and the third moving lens group Zoom lens. [Appendix 2] The second optical system includes, on the most reduced side, a fixed lens group fixed with respect to the reduced-side imaging surface during zooming. The zoom lens according to Appendix 1. [Appendix 3] The fixed lens group has a positive refractive power. The zoom lens according to Appendix 2. [Appendix 4] The reduced side is configured to be telecentric. The zoom lens according to Appendix 2 or Appendix 3. [Appendix 5] The second moving lens group has a negative refractive power. The zoom lens according to any one of Appendices 1 to 4. [Appendix 6] When the focal length of the zoom lens at the wide-angle end is fw and the focal length of the first optical system is fr1, 0.8 < fr1 / |fw| < 5 (1) The zoom lens according to any one of Appendices 1 to 5 that satisfies the conditional expression (1) represented by the above. [Appendix 7] The first optical system includes a positive lens, a negative lens, and a cemented lens in which a positive lens and a negative lens are cemented in this order. The zoom lens according to any one of Appendices 1 to 6. [Appendix 8] The effective diameter of the enlarged-side surface of the second lens from the enlarged side of the first optical system at the wide-angle end is smaller than the effective diameter of the enlarged-side surface of the most reduced-side lens of the first optical system at the wide-angle end. The zoom lens according to any one of Appendices 1 to 7. [Appendix 9] The second moving lens group consists of one negative lens and one positive lens. The zoom lens according to any one of Appendices 1 to 8. [Appendix 10] When the focal length of the first moving lens group is f1, the focal length of the second moving lens group is f2, and the focal length of the third moving lens group is f3, 0 < |f1 / f2| < 0.75 (2) 0 < |f3 / f2| < 0.75 (3) The zoom lens according to any one of Appendices 1 to 9 that satisfies the conditional expressions (2) and (3) represented by [Appendix 11] 0 < |f1 / f2| < 0.5 (2-2) 0 < |f3 / f2| < 0.5 (3-2) The zoom lens according to Appendix 10 that satisfies the conditional expressions (2-2) and (3-2) represented by [Appendix 12] When the focal length of the first moving lens group is f1, and the focal length of the third moving lens group is f3, 0.5 < f1 / f3 < 2 (4) The zoom lens according to any one of Appendices 1 to 11 that satisfies the conditional expression (4) represented by [Appendix 13] The first moving lens group at the telephoto end is located on the magnifying side with respect to the first moving lens group at the wide-angle end, the second moving lens group at the telephoto end is located on the magnifying side with respect to the second moving lens group at the wide-angle end, and the third moving lens group at the telephoto end is located on the magnifying side with respect to the third moving lens group at the wide-angle end The zoom lens according to any one of Appendices 1 to 12 [Appendix 14] During zooming from the wide-angle end to the telephoto end, the first moving lens group, the second moving lens group, and the third moving lens group always move toward the magnifying side, respectively The zoom lens according to Appendix 13 [Appendix 15] A first optical path bending member for bending the optical path is disposed within the first optical system The zoom lens according to any one of Appendices 1 to 14 [Appendix 16] A second optical path bending member for bending the optical path is disposed on the reducing side with respect to the first optical system The zoom lens according to any one of Supplementary Note 1 to Supplementary Note 14. [Supplementary Note 17] A first optical path bending member for bending the optical path is arranged in the first optical system. A second optical path bending member for bending the optical path is arranged on the reduction side of the first optical system. The zoom lens according to any one of Supplementary Note 1 to Supplementary Note 14. [Supplementary Note 18] The first optical system has a positive refractive power and is fixed with respect to the reduction-side imaging surface during zooming. The second optical system includes, in order along the optical path from the enlargement side to the reduction side, the first moving lens group, the second moving lens group, the third moving lens group, and a fixed lens group fixed with respect to the reduction-side imaging surface during zooming. The zoom lens according to any one of Supplementary Note 1 to Supplementary Note 17. [Supplementary Note 19] A projection display device including the zoom lens according to any one of Supplementary Note 1 to Supplementary Note 18. [Supplementary Note 20] An imaging device including the zoom lens according to any one of Supplementary Note 1 to Supplementary Note 18.

Explanation of Reference Signs

[0147] 10 Zoom lens 11a~11c Transmission display element 12 Dichroic mirror 13 Dichroic mirror 14 Cross-dichroic prism 15 Light source 16a~16c Condenser lens 18a~18c Total reflection mirror 21a~21c DMD element 24a~24c TIR prism 25 Polarizing beam splitter prism 31a~31c Reflective display element 32 Dichroic mirror 33 Dichroic mirror 34 Cross-dichroic prism 35a - 35c Polarization beam splitting prism 38 Total reflection mirror 41 Camera body 42 Shutter button 43 Power button 44 Operation unit 45 Operation unit 46 Display unit 47 Mount 48 Interchangeable lens 49 Zoom lens 50 Image sensor 100 Projection display device 105 Screen 200 Projection display device 205 Screen 210 Zoom lens 215 Light source 300 Projection display device 305 Screen 310 Zoom lens 315 Light source 400 Camera G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group Gf Focus group Ka On - axis light beam Kb Light beam of maximum picture angle L1 - L31 Lenses PP Optical member R1, R2 Mirrors Sim Image display surface St Aperture stop U1, U1r First optical system U2, U2r Second optical system Z Optical axis

Claims

1. A zoom lens comprising a first optical system and a second optical system in order along the optical path from the wide-angle side to the telephoto side, wherein the second optical system forms an intermediate image at a position conjugate to the telephoto-side imaging surface, and the first optical system re-images the intermediate image onto the wide-angle-side imaging surface, the lens on the most wide-angle side of the second optical system is a positive lens with a convex surface facing the wide-angle side, when a group whose interval in the optical axis direction with an adjacent group changes during zooming is regarded as one lens group, the second optical system includes, in order along the optical path from the most wide-angle side to the telephoto side, a first moving lens group having a positive refractive power that moves during zooming, a second moving lens group that moves during zooming, and a third moving lens group having a positive refractive power that moves during zooming, among the entire zoom lens, the lens groups that move during zooming are only the first moving lens group, the second moving lens group, and the third moving lens group Zoom lens.

2. The second optical system includes, on the most telephoto side, a fixed lens group that is fixed with respect to the telephoto-side imaging surface during zooming The zoom lens according to claim 1.

3. The fixed lens group has a positive refractive power The zoom lens according to claim 2.

4. The telephoto side is configured to be telecentric The zoom lens according to claim 2.

5. The second moving lens group has a negative refractive power The zoom lens according to claim 1.

6. When the focal length of the zoom lens at the wide-angle end is fw and the focal length of the first optical system is fr1, 0.8 < fr1 / |fw| < 5 (1) The zoom lens according to claim 1 that satisfies the conditional expression (1) represented by

7. The first optical system includes a cemented lens in which a positive lens, a negative lens, and a positive lens are cemented in order The zoom lens according to claim 1.

8. The effective diameter of the wide-angle-side surface of the second lens from the wide-angle side of the first optical system at the wide-angle end is smaller than the effective diameter of the wide-angle-side surface of the most telephoto-side lens of the first optical system at the wide-angle end The zoom lens according to claim 1.

9. The second moving lens group consists of one negative lens and one positive lens The zoom lens according to claim 1.

10. When the focal length of the first moving lens group is f1, the focal length of the second moving lens group is f2, and the focal length of the third moving lens group is f3, 0 < |f1 / f2| < 0.75 (2) 0 < |f3 / f2| < 0.75 (3) The zoom lens according to claim 1, which satisfies the conditional expressions (2) and (3) represented by

11. 0 < |f1 / f2| < 0.5 (2-2) 0 < |f3 / f2| < 0.5 (3-2) The zoom lens according to claim 10, which satisfies the conditional expressions (2-2) and (3-2) represented by

12. When the focal length of the first moving lens group is f1, and the focal length of the third moving lens group is f3, 0.5 < f1 / f3 < 2 (4) The zoom lens according to claim 1, which satisfies the conditional expression (4) represented by

13. The first moving lens group at the telephoto end is located on the magnifying side with respect to the first moving lens group at the wide-angle end, the second moving lens group at the telephoto end is located on the magnifying side with respect to the second moving lens group at the wide-angle end, and the third moving lens group at the telephoto end is located on the magnifying side with respect to the third moving lens group at the wide-angle end The zoom lens according to claim 1.

14. When zooming from the wide-angle end to the telephoto end, the first moving lens group, the second moving lens group, and the third moving lens group always move toward the magnifying side, respectively The zoom lens according to claim 13.

15. A first optical path bending member for bending the optical path is disposed within the first optical system The zoom lens according to claim 1.

16. A second optical path bending member for bending the optical path is disposed on the reducing side with respect to the first optical system The zoom lens according to claim 1.

17. A first optical path bending member for bending the optical path is disposed within the first optical system, and a second optical path bending member for bending the optical path is disposed on the reducing side with respect to the first optical system The zoom lens according to claim 1.

18. The first optical system has a positive refractive power and is fixed with respect to the reducing-side imaging surface during zooming, and the second optical system includes, in order along the optical path from the magnifying side to the reducing side, the first moving lens group, the second moving lens group, the third moving lens group, and a fixed lens group fixed with respect to the reducing-side imaging surface during zooming The zoom lens according to claim 1.

19. A projection display device including the zoom lens according to any one of claims 1 to 18.

20. An imaging device including the zoom lens according to any one of claims 1 to 18.

Images