Optical system, image projection apparatus, and imaging apparatus

Abstract

This optical system has, in the interior thereof, an intermediate imaging position (MI) conjugated to each of a magnification conjugate point on the magnification side and a reduction conjugate point on the reduction side, and is provided with: a magnification optical system (Op) that has a plurality of lens elements and is positioned closer to the magnification side than the intermediate imaging position (MI); and a relay optical system (O1) having a plurality of lens elements and positioned closer to the reduction side than the intermediate imaging position (MI). A first lens element (L1) located closest to the magnification side of the magnification optical system (Op) has a positive refractive power. The optical system satisfies 0.9 < = f1 / f2 < = 1.5 (f1: focal length of the magnifying optical system (Op), and f2: focal length of the relay optical system (O1)).

Description

Technical Field

[0001] The present disclosure relates to an optical system for forming an intermediate image and to an image projection device and an imaging device using such an optical system. Background Art

[0002] The optical system of the intermediate imaging method has the advantage of being able to achieve wide-angle projection of a large screen with a short focus. However, the wider the angle, the greater the change in aberrations such as image plane curvature and astigmatism when adjusting the focus according to the object distance, and the optical performance may decrease. Patent document 1 discloses a wide-angle imaging optical system, which performs focus adjustment through two focus groups that are closer to the magnification side than the intermediate imaging. Patent document 2 discloses a wide-angle imaging optical system, which performs focus adjustment through two or three focus groups.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-97046

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-132904 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The present disclosure provides an optical system that can easily widen the angle, easily reduce distortion, and achieve a relatively long back focus. In addition, the present disclosure provides an image projection device and an imaging device using such an optical system.

[0009] Means for solving problems

[0010] The optical system disclosed herein has an intermediate imaging position conjugated to an enlargement conjugate point on an enlargement side and a reduction conjugate point on a reduction side, respectively, and comprises: an enlargement optical system having a plurality of lens elements located at a position closer to the enlargement side than the intermediate imaging position; and a relay optical system having a plurality of lens elements located at a position closer to the reduction side than the intermediate imaging position, wherein a first lens element of the enlargement optical system located at a position closest to the enlargement side has positive optical power,

[0011] The optical system satisfies the following condition (1):

[0012] 0.9≤f1 / f2≤1.5 (1)

[0013] Here,

[0014] f1: focal length of the magnifying optical system;

[0015] f2: focal length of the relay optical system.

[0016] Furthermore, an image projection device according to the present disclosure includes: the above-mentioned optical system; and an image forming element for generating an image to be projected onto a screen via the optical system.

[0017] Furthermore, an imaging device according to the present disclosure includes: the above-mentioned optical system; and an imaging element that receives an optical image formed by the optical system and converts the optical image into an electrical image signal.

[0018] Effects of the Invention

[0019] According to the optical system involved in the present disclosure, it is easy to widen the angle, it is easy to reduce distortion aberration, and it is possible to achieve a relatively long back focus. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a diagram showing the arrangement of optical paths of the zoom lens system of Example 1 at the wide-angle end when the object distance is 3000 mm.

[0021] Figure 2 This is a diagram showing the arrangement of the zoom lens system of Example 1 at the wide-angle end at an object distance of 3000 mm.

[0022] Figure 3 This is a longitudinal aberration diagram of the zoom lens system of Example 1 at an object distance of 3000 mm.

[0023] Figure 4 This is a longitudinal aberration diagram of the zoom lens system of Example 1 at an object distance of 1800 mm.

[0024] Figure 5 This is a diagram showing the arrangement of the zoom lens system of Example 1 at the wide-angle end at an object distance of 20,000 mm.

[0025] Figure 6 1 is a diagram showing the arrangement of optical paths of the zoom lens system of Example 2 at the wide-angle end at an object distance of 3000 mm.

[0026] Figure 7 This is a diagram showing the arrangement of the zoom lens system of Example 2 at the wide-angle end at an object distance of 3000 mm.

[0027] Figure 8 This is a longitudinal aberration diagram of the zoom lens system of Example 2 at an object distance of 3000 mm.

[0028] Fig. 9 This is a longitudinal aberration diagram of the zoom lens system of Example 2 at an object distance of 1800 mm.

[0029] Fig.10 This is a diagram showing the arrangement of the zoom lens system of Example 2 at the wide-angle end at an object distance of 20,000 mm.

[0030] Fig.11 1 is a diagram showing the arrangement of optical paths of the zoom lens system of Example 3 at the wide-angle end at an object distance of 3000 mm.

[0031] Fig.12 This is a diagram showing the arrangement of the zoom lens system of Example 3 at the wide-angle end at an object distance of 3000 mm.

[0032] Fig.13 This is a longitudinal aberration diagram of the zoom lens system of Example 3 at an object distance of 3000 mm.

[0033] Fig.14 This is a longitudinal aberration diagram of the zoom lens system of Example 3 at an object distance of 1800 mm.

[0034] Fig.15 This is a diagram showing the arrangement of the zoom lens system of Example 3 at the wide-angle end at an object distance of 20,000 mm.

[0035] Fig.16 1 is a diagram showing the arrangement of optical paths of the zoom lens system of Example 4 at the wide-angle end at an object distance of 3000 mm.

[0036] Fig.17 This is a diagram showing the arrangement of the zoom lens system of Example 4 at the wide-angle end at an object distance of 3000 mm.

[0037] Fig.18 This is a longitudinal aberration diagram of the zoom lens system of Example 4 at an object distance of 3000 mm.

[0038] Fig.19 This is a longitudinal aberration diagram of the zoom lens system of Example 4 at an object distance of 1800 mm.

[0039] Fig. 20 This is a diagram showing the arrangement of the zoom lens system of Example 4 at the wide-angle end at an object distance of 20,000 mm.

[0040] Fig.21 : is a block diagram showing an example of the image projection device involved in the present disclosure.

[0041] Fig. 22 This is a block diagram showing an example of an imaging device according to the present disclosure. DETAILED DESCRIPTION

[0042] Below, with appropriate reference to the attached Figure 1 The embodiments are described in detail. However, sometimes more detailed descriptions than necessary are omitted. For example, sometimes detailed descriptions of well-known matters or repeated descriptions of substantially the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to make it easy for those skilled in the art to understand.

[0043] In addition, the applicant provides the drawings and the following description in order to allow those skilled in the art to fully understand the present disclosure, but the applicant does not intend to limit the subject matter described in the claims thereby.

[0044] Hereinafter, various embodiments of the optical system involved in the present disclosure will be described. In each embodiment, a case where the optical system is used in a projector (an example of an image projection device) is described, and the projector projects image light of an original image S obtained by spatially modulating incident light based on an image signal by an image forming element such as a liquid crystal or a DMD (digital micromirror device) onto a screen. That is, the optical system involved in the present disclosure can be used to configure a screen (not shown) on an extension line of the magnification side and enlarge the original image S on the image forming element arranged on the reduction side and project it onto the screen.

[0045] Furthermore, the optical system according to the present disclosure can also be used to collect light emitted from an object located on an extension line on the magnification side, and form an optical image of the object on an imaging surface of an imaging element arranged on the reduction side.

[0046] (Implementation Method 1)

[0047] Below, use Figures 1 to 20 Embodiment 1 of the present disclosure will be described. Here, a zoom lens system will be described as an example of an optical system.

[0048] Figure 1 , 6 , 11, and 16 are arrangement diagrams showing optical paths at the wide-angle end at an object distance of 3000 mm in the zoom lens systems according to Examples 1 to 4. Figure 2 , 7 , 12, and 17 are configuration diagrams of the zoom lens systems involved in Examples 1 to 4 at the wide-angle end at an object distance of 3000 mm. Figure 2 (a) Figure 7 (a) Fig.12 (a) Fig.17 (a) shows a lens configuration diagram of the zoom lens system at the wide-angle end. Figure 2 (b) Figure 7 (b) Fig.12 (b) Fig.17 (b) shows a lens configuration diagram at an intermediate position of the zoom lens system. Figure 2 (c) Figure 7 (c) Fig.12 (c) Fig.17 (c) shows a lens configuration diagram of the zoom lens system at the telephoto end.

[0049] exist Figure 2 (a) Figure 7 (a) Fig.12 (a) Fig.17 The arrow of the broken line in the lower part of (a) is a straight line connecting the positions of the first lens group G1 to the fourth lens group G4 in the wide-angle end, the middle position and the telephoto end from the top of the figure. Simply connecting the wide-angle end and the middle position, and the middle position and the telephoto end with straight lines is different from the actual movement of each lens group G1 to G4. In addition, the symbols (+) and (-) marked on the symbols of each lens group G1 to G4 indicate the positive and negative optical power of each lens group G1 to G4.

[0050] The wide-angle end is the shortest focal length state where the entire system has the shortest focal length fw. The intermediate position is the intermediate focal length state between the wide-angle end and the telephoto end. The telephoto end is the longest focal length state where the entire system has the longest focal length ft. The focal length of the intermediate position is specified based on the focal length fw at the wide-angle end and the focal length ft at the telephoto end.

[0051] The zoom lens system according to Examples 1 to 4 has an intermediate imaging position MI which is conjugated with the magnification conjugate point on the magnification side and the reduction conjugate point on the reduction side. The magnification optical system Op is arranged at a position closer to the magnification side than the intermediate imaging position MI, and the relay optical system Ol is arranged at a position closer to the reduction side than the intermediate imaging position MI. The optical elements P1, P2, and P3 are arranged at a position closer to the reduction side than the relay optical system Ol.

[0052] Regarding the zoom function, the zoom lens system involved in Examples 1 and 3 includes a first lens group G1 to a fourth lens group G4 that can move independently of each other. The first lens group G1 has positive optical power, is composed of a first lens element L1 to a fourteenth lens element L14, and includes surfaces 1 to 28 (for surface numbers, refer to the numerical examples described later). The second lens group G2 has positive optical power, is composed of a fifteenth lens element L15, and includes surfaces 29 to 30. The third lens group G3 has positive optical power, is composed of a sixteenth lens element L16 to an eighteenth lens element L18, and includes surfaces 31 to 36. The fourth lens group G4 has positive optical power, is composed of a nineteenth lens element L19 to a twenty-fifth lens element L25, and includes surfaces 38 to 51. The optical elements P1, P2, and P3 include surfaces 52 to 57.

[0053] Figure 2 and Fig.12 The first lens group G1 shown in FIG. Figure 1 and Fig.11 The enlarging optical system Op and the first relay lens group GL1 shown correspond to each other. Figure 2 and Fig.12 The second to fourth lens groups G2 to G4 shown are respectively Figure 1 and Fig.11The second to fourth relay lens groups GL2 to GL4 shown in the figure correspond to each other. When zooming from the wide angle end to the telephoto end, as shown in FIG. Figure 2 and Fig.12 As shown, the first lens group G1 is fixed, and the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the magnification side.

[0054] The zoom lens system involved in Example 2 includes a first lens group G1 to a fourth lens group G4 that can move independently of each other. The first lens group G1 has positive optical power, is composed of a first lens element L1 to a twelfth lens element L12, and includes surfaces 1 to 24. The second lens group G2 has positive optical power, is composed of a thirteenth lens element L13, and includes surfaces 25 to 26. The third lens group G3 has positive optical power, is composed of a fourteenth lens element L14 to a sixteenth lens element L16, and includes surfaces 27 to 32. The fourth lens group G4 has positive optical power, is composed of an eighteenth lens element L18 to a twenty-third lens element L23, and includes surfaces 34 to 47. The optical elements P1, P2, and P3 include surfaces 48 to 53.

[0055] Figure 7 The first lens group G1 shown in FIG. Figure 6 The enlarging optical system Op and the first relay lens group GL1 shown correspond to each other. Figure 7 The second to fourth lens groups G2 to G4 shown are respectively Figure 6 The second to fourth relay lens groups GL2 to GL4 shown in the figure correspond to each other. When zooming from the wide angle end to the telephoto end, as shown in FIG. Figure 7 As shown, the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move toward the magnification side.

[0056] The zoom lens system involved in Example 4 includes a first lens group G1 to a fourth lens group G4 that can move independently of each other. The first lens group G1 has positive optical power, is composed of a first lens element L1 to a fifteenth lens element L15, and includes surfaces 1 to 30. The second lens group G2 has positive optical power, is composed of a sixteenth lens element L16, and includes surfaces 31 to 32. The third lens group G3 has positive optical power, is composed of a seventeenth lens element L17 to a nineteenth lens element L19, and includes surfaces 33 to 38. The fourth lens group G4 has positive optical power, is composed of a 20th lens element L20 to a 26th lens element L26, and includes surfaces 40 to 53. The optical elements P1, P2, and P3 include surfaces 54 to 59.

[0057] Fig.17 The first lens group G1 shown in FIG. Fig.16 The enlarging optical system Op and the first relay lens group GL1 shown correspond to each other. Fig.17The second to fourth lens groups G2 to G4 shown are respectively Fig.16 The second to fourth relay lens groups GL2 to GL4 shown in the figure correspond to each other. When zooming from the wide angle end to the telephoto end, as shown in FIG. Fig.17 As shown, the first lens group G1 is fixed, and the second lens group G2, the third lens group G3, and the fourth lens group G4 move toward the magnification side.

[0058] Regarding the focusing function, the zoom lens system according to Examples 1 to 4 may include, as necessary, a focus lens group for performing focus adjustment when the object distance changes, and a field curvature correction lens group for correcting field curvature aberration after the focus lens group performs focus adjustment.

[0059] As an example, in the zoom lens system according to Embodiments 1 and 3, Figure 1 and Fig.11 As shown in FIG. 1 , the image curvature correction lens group GCC is composed of the 9th lens element L9 to the 12th lens element L12. In the zoom lens system involved in Example 2, as shown in FIG. Figure 6 As shown in FIG. 1 , the image curvature correction lens group GCC is composed of the seventh lens element L7 to the eighth lens element L8. In the zoom lens system involved in Example 4, as shown in FIG. Fig.16 As shown, the image curvature correction lens group GCC is composed of the 10th lens element L10 to the 13th lens element L13. When performing the image curvature correction operation, the image curvature correction lens group GCC moves along the optical axis of the magnification optical system Op, and the lens elements located closer to the magnification side than the image curvature correction lens group GCC are fixed.

[0060] In each figure, the image forming position on the magnification side (i.e., the magnification conjugate point) is located on the left, and the image forming position on the reduction side (i.e., the reduction conjugate point) is located on the right. In addition, in each figure, the straight line closest to the reduction side represents the position of the original image S, and the optical elements P1, P2, and P3 are located on the magnification side of the original image S. The optical power of the optical elements P1, P2, and P3 is zero, and they represent optical elements such as a color separation prism, a color synthesis prism, an optical filter, a parallel plate glass, a quartz low-pass filter, and an infrared cutoff filter.

[0061] Figure 3 , 8 , 13, and 18 are longitudinal aberration diagrams of the zoom lens system involved in Examples 1 to 4 at an object distance of 3000 mm. Figure 4 , 9 , 14, and 19 are longitudinal aberration diagrams of the zoom lens system involved in Examples 1 to 4 at an object distance of 1800 mm. Figure 5 , 10, 15, and 20 are longitudinal aberration diagrams at an object distance of 20000 mm of the zoom lens system according to Examples 1 to 4. (a), (b), and (c) in each figure are longitudinal aberration diagrams at the wide angle end, the intermediate position, and the telephoto end of the zoom lens system.

[0062] The longitudinal aberration diagrams show spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) in order from the left. In the spherical aberration diagram, the vertical axis represents the height of the pupil, the solid line is the characteristic of the d-line, the short dashed line is the characteristic of the F-line, and the long dashed line is the characteristic of the C-line. In the astigmatism diagram, the vertical axis represents the image height, the solid line is the characteristic of the sagittal plane (indicated by s in the diagram), and the dashed line is the characteristic of the meridional plane (indicated by m in the diagram). In the distortion diagram, the vertical axis represents the image height. In addition, the distortion aberration represents the distortion aberration relative to the equidistant projection.

[0063] (Example 1)

[0064] like Figure 1 , 2 As shown, the zoom lens system involved in Example 1 includes a magnifying optical system Op and a relay optical system O1. The magnifying optical system Op is composed of a first lens element L1 to a twelfth lens element L12 in order from the magnification side to the reduction side. The first lens element L1 has a positive meniscus shape with a convex surface facing the magnification side. The second lens element L2 has a negative meniscus shape with a convex surface facing the magnification side. The third lens element L3 has a negative meniscus shape with a convex surface facing the magnification side. The fourth lens element L4 has a positive meniscus shape with a convex surface facing the reduction side. The fifth lens element L5 has a negative meniscus shape with a convex surface facing the reduction side. The sixth lens element L6 has a positive meniscus shape with a convex surface facing the reduction side. The seventh lens element L7 has a biconvex shape. The eighth lens element L8 has a biconvex shape. The ninth lens element L9 has a biconcave shape. The tenth lens element L10 has a positive meniscus shape with a convex surface facing the reduction side. The eleventh lens element L11 has a positive meniscus shape with a convex surface facing the magnification side. The twelfth lens element L12 has a positive meniscus shape with a convex surface facing the magnification side.

[0065] The relay optical system O1 is composed of the 13th lens element L13 to the 25th lens element L25 in order from the magnification side to the reduction side. The 13th lens element L13 has a biconcave shape. The 14th lens element L14 has a positive meniscus shape with the convex surface facing the reduction side. The 15th lens element L15 has a biconvex shape. The 16th lens element L16 has a biconcave shape. The 17th lens element L17 has a biconvex shape. The 18th lens element L18 has a biconvex shape. The 19th lens element L19 has a biconcave shape. The 20th lens element L20 has a biconvex shape. The 21st lens element L21 has a negative meniscus shape with the convex surface facing the magnification side. The 22nd lens element L22 has a negative meniscus shape with the convex surface facing the reduction side. The 23rd lens element L23 has a positive meniscus shape with the convex surface facing the reduction side. The 24th lens element L24 has a biconvex shape. The 25th lens element L25 has a biconvex shape.

[0066] An intermediate image forming position MI exists between the 12th lens element L12 and the 13th lens element L13. A stop A is disposed between the 18th lens element L18 and the 19th lens element L19. Optical elements P1, P2, and P3 having zero optical power are disposed on the reduction side of the relay optical system O1.

[0067] (Example 2)

[0068] like Figure 6 , 7 As shown, the zoom lens system involved in Example 2 includes a magnifying optical system Op and a relay optical system O1. The magnifying optical system Op is composed of the first lens element L1 to the tenth lens element L10 in order from the magnification side to the reduction side. The first lens element L1 has a positive meniscus shape with the convex surface facing the magnification side. The second lens element L2 has a negative meniscus shape with the convex surface facing the magnification side. The third lens element L3 has a positive meniscus shape with the convex surface facing the reduction side. The fourth lens element L4 has a negative meniscus shape with the convex surface facing the reduction side. The fifth lens element L5 has a positive meniscus shape with the convex surface facing the reduction side. The sixth lens element L6 has a biconvex shape. The seventh lens element L7 has a positive meniscus shape with the convex surface facing the magnification side. The eighth lens element L8 has a biconcave shape. The ninth lens element L9 has a biconvex shape. The tenth lens element L10 has a positive meniscus shape with the convex surface facing the magnification side.

[0069] The relay optical system Ol is composed of the 11th lens element L11 to the 23rd lens element L23 in order from the magnification side to the reduction side. The 11th lens element L11 has a biconcave shape. The 12th lens element L12 has a positive meniscus shape with the convex surface facing the reduction side. The 13th lens element L13 has a biconvex shape. The 14th lens element L14 has a biconcave shape. The 15th lens element L15 has a biconvex shape. The 16th lens element L16 has a positive meniscus shape with the convex surface facing the magnification side. The 17th lens element L17 has a biconcave shape. The 18th lens element L18 has a positive meniscus shape with the convex surface facing the reduction side. The 19th lens element L19 has a negative meniscus shape with the convex surface facing the magnification side. The 20th lens element L20 has a negative meniscus shape with the convex surface facing the reduction side. The 21st lens element L21 has a positive meniscus shape with the convex surface facing the reduction side. The 22nd lens element L22 has a biconvex shape. The 23rd lens element L23 has a biconvex shape.

[0070] An intermediate image forming position MI exists between the tenth lens element L10 and the eleventh lens element L11. A stop A is disposed between the sixteenth lens element L16 and the seventeenth lens element L17. Optical elements P1, P2, and P3 having zero optical power are disposed on the reduction side of the relay optical system Ol.

[0071] (Example 3)

[0072] like Fig.11 , 12 As shown, the zoom lens system involved in Example 3 includes a magnifying optical system Op and a relay optical system O1. The magnifying optical system Op is composed of a first lens element L1 to a twelfth lens element L12 in order from the magnification side to the reduction side. The first lens element L1 has a positive meniscus shape with a convex surface facing the magnification side. The second lens element L2 has a negative meniscus shape with a convex surface facing the magnification side. The third lens element L3 has a negative meniscus shape with a convex surface facing the magnification side. The fourth lens element L4 has a positive meniscus shape with a convex surface facing the reduction side. The fifth lens element L5 has a negative meniscus shape with a convex surface facing the reduction side. The sixth lens element L6 has a positive meniscus shape with a convex surface facing the reduction side. The seventh lens element L7 has a biconvex shape. The eighth lens element L8 has a biconvex shape. The ninth lens element L9 has a biconcave shape. The tenth lens element L10 has a positive meniscus shape with a convex surface facing the reduction side. The eleventh lens element L11 has a positive meniscus shape with a convex surface facing the magnification side. The twelfth lens element L12 has a positive meniscus shape with a convex surface facing the magnification side.

[0073] The relay optical system O1 is composed of the 13th lens element L13 to the 25th lens element L25 in order from the magnification side to the reduction side. The 13th lens element L13 has a biconcave shape. The 14th lens element L14 has a positive meniscus shape with the convex surface facing the reduction side. The 15th lens element L15 has a biconvex shape. The 16th lens element L16 has a biconcave shape. The 17th lens element L17 has a biconvex shape. The 18th lens element L18 has a biconcave shape. The 19th lens element L19 has a biconcave shape. The 20th lens element L20 has a biconvex shape. The 21st lens element L21 has a negative meniscus shape with the convex surface facing the magnification side. The 22nd lens element L22 has a negative meniscus shape with the convex surface facing the reduction side. The 23rd lens element L23 has a positive meniscus shape with the convex surface facing the reduction side. The 24th lens element L24 has a biconvex shape. The 25th lens element L25 has a biconvex shape.

[0074] An intermediate image forming position MI exists between the 12th lens element L12 and the 13th lens element L13. A stop A is arranged between the 18th lens element L18 and the 19th lens element L19. Optical elements P1, P2, and P3 having zero optical power are arranged on the reduction side of the relay optical system Ol.

[0075] (Example 4)

[0076] like Fig.16 , 17 As shown, the zoom lens system involved in Example 4 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op is composed of the first lens element L1 to the thirteenth lens element L13 in order from the magnification side to the reduction side. The first lens element L1 has a positive meniscus shape with the convex surface facing the magnification side. The second lens element L2 has a negative meniscus shape with the convex surface facing the magnification side. The third lens element L3 has a negative meniscus shape with the convex surface facing the magnification side. The fourth lens element L4 is a zero optical power element having a refractive index greater than 1, for example, composed of a flat plate shape with two flat surfaces. The fifth lens element L5 has a positive meniscus shape with the convex surface facing the reduction side. The sixth lens element L6 has a negative meniscus shape with the convex surface facing the reduction side. The seventh lens element L7 has a positive meniscus shape with the convex surface facing the reduction side. The eighth lens element L8 has a positive meniscus shape with the convex surface facing the reduction side. The ninth lens element L9 has a biconvex shape. The tenth lens element L10 has a biconcave shape. The 11th lens element L11 has a biconvex shape. The 12th lens element L12 has a positive meniscus shape with a convex surface facing the magnification side. The 13th lens element L13 has a positive meniscus shape with a convex surface facing the magnification side.

[0077] The relay optical system Ol is composed of the 14th lens element L14 to the 26th lens element L26 in order from the magnification side to the reduction side. The 14th lens element L14 has a biconcave shape. The 15th lens element L15 has a positive meniscus shape with the convex surface facing the reduction side. The 16th lens element L16 has a biconvex shape. The 17th lens element L17 has a biconcave shape. The 18th lens element L18 has a biconvex shape. The 19th lens element L19 has a biconvex shape. The 20th lens element L20 has a biconcave shape. The 21st lens element L21 has a biconvex shape. The 22nd lens element L22 has a negative meniscus shape with the convex surface facing the magnification side. The 23rd lens element L23 has a negative meniscus shape with the convex surface facing the reduction side. The 24th lens element L24 has a positive meniscus shape with the convex surface facing the reduction side. The 25th lens element L25 has a biconvex shape. The 26th lens element L26 has a biconvex shape.

[0078] An intermediate image forming position MI exists between the 13th lens element L13 and the 14th lens element L14. A stop A is disposed between the 19th lens element L19 and the 20th lens element L20. Optical elements P1, P2, and P3 having zero optical power are disposed on the reduction side of the relay optical system O1.

[0079] Next, conditions that can be satisfied by the zoom lens system according to the present embodiment are described. In addition, a plurality of conditions are specified for the zoom lens system according to each embodiment, but all of these conditions may be satisfied, or corresponding effects may be obtained by satisfying a single condition.

[0080] The zoom lens system according to Examples 1 to 4 has an intermediate image forming position MI which is conjugated with an enlargement conjugate point on the enlargement side and a reduction conjugate point on the reduction side, respectively, and comprises: an enlargement optical system Op having a plurality of lens elements and located at a position closer to the enlargement side than the intermediate image forming position MI; and a relay optical system O1 having a plurality of lens elements and located at a position closer to the reduction side than the intermediate image forming position MI. The first lens element L1 of the enlargement optical system Op located at the position closest to the enlargement side has positive refractive power.

[0081] The optical system satisfies the following condition (1).

[0082] 0.9≤f1 / f2≤1.5 (1)

[0083] Here,

[0084] f1: focal length of the magnifying optical system Op;

[0085] f2.: Focal length of the relay optical system O1.

[0086] According to such a structure, it is easy to widen the angle and reduce the distortion aberration. Therefore, even if an aspherical lens is not used, the distortion aberration can be suppressed to a sufficient level. In addition, the back focal length becomes longer, the interval between the relay optical system and the reduced conjugate point can be increased, and large optical elements can be configured, for example, a color separation prism and a color synthesis prism for RGB3 colors can be configured. If it is lower than the lower limit of condition (1), it becomes difficult to correct the distortion aberration. If it exceeds the upper limit, the outer diameter of the lens becomes larger.

[0087] Furthermore, the zoom lens systems according to Examples 1 to 4 may also satisfy the following condition (2).

[0088] 2.0<(L1R2+L1R1) / (L1R2-L1R1)<5.0 (2)

[0089] Here,

[0090] L1R1. The radius of curvature of the surface of the magnification side of the first lens element L1;

[0091] L1R2. The curvature radius of the surface on the reduction side of the first lens element L1.

[0092] Condition (2) is related to the shape factor of the lens. By satisfying condition (2), the outer diameter of the first lens element can be maintained at an appropriate size and distortion aberration can be easily reduced. If it is lower than the lower limit of condition (2), the outer diameter of the lens becomes larger. If it exceeds the upper limit, it becomes difficult to correct the distortion aberration.

[0093] Furthermore, in the zoom lens systems according to Examples 1 to 4, the first lens element L1 may have a refractive index of 1.8 or more.

[0094] According to such a configuration, the optical power of the first lens element is increased, and thus the outer diameter of the first lens element can be reduced.

[0095] In addition, regarding the zoom lens system involved in Examples 1 to 4, the magnifying optical system Op may also include, in sequence from the magnification side to the reduction side, the first lens element L1 having positive optical power, the second lens element L2 having negative optical power other than the first lens element L1, and the third lens element L3 having negative optical power.

[0096] According to such a configuration, by adopting a positive-negative-negative lens arrangement, it is easy to widen the angle and reduce distortion.

[0097] In addition, the zoom lens system involved in Examples 1 to 4 may also be configured with only the first lens element L1, the second lens element L2 and the third lens element L3 as optical elements having optical focal power within the range from the surface on the magnification side of the first lens element L1 to the position where the most off-axis light ray intersects the optical axis of the magnification optical system.

[0098] According to such a structure, the outer diameter of the first lens element can be reduced. In addition, the total length of the optical system can be shortened. In addition, an element with zero optical power can be arranged within the above range.

[0099] Furthermore, in the zoom lens systems according to Examples 1 to 4, the surface shapes of the plurality of lens elements constituting the magnifying optical system Op and the plurality of lens elements constituting the relay optical system O1 may be spherical surfaces or flat surfaces.

[0100] According to such a configuration, the manufacturing cost of the optical system can be reduced compared to the case where an aspherical lens is used.

[0101] Furthermore, the zoom lens systems according to Examples 1 to 4 may also satisfy the following conditions.

[0102] 5<|L1f / fw|<10 (3)

[0103] Here,

[0104] L1f: focal length of the first lens element L1;

[0105] fw. The focal length of the entire optical system at the wide-angle end.

[0106] By satisfying condition (3), the relationship between the focal length L1f of the first lens element and the focal length fw of the entire optical system at the wide angle end can be optimized. If the lower limit of condition (3) is exceeded, the outer diameter of the first lens element becomes large, making it difficult to manufacture. If the upper limit is exceeded, it becomes difficult to correct distortion aberration.

[0107] In addition, regarding the zoom lens system involved in Examples 1 to 4, it may be that the magnifying optical system Op includes an image curvature correction lens group with positive optical focal length adjacent to the intermediate imaging position MI on the magnification side, and when performing an image curvature correction action, the image curvature correction lens group moves along the optical axis of the magnifying optical system Op, and the lens element located at a position closer to the magnification side than the image curvature correction lens group and the relay optical system are fixed.

[0108] According to such a configuration, when performing field curvature correction operation, the change in back focus can be reduced more by moving the field curvature correction lens group adjacent to the magnification side from the intermediate imaging position than by moving the lens element located on the magnification side of the magnification optical system.

[0109] In the zoom lens system according to Examples 1 to 4, in the field curvature correction lens group, the lens element located most toward the magnification side may have negative refractive power, and the lens element located most toward the reduction side may have positive refractive power.

[0110] According to such a configuration, when performing the field curvature correction operation, it is possible to reduce the change in lateral chromatic aberration caused by the movement of the field curvature correction lens group.

[0111] Furthermore, the zoom lens systems according to Examples 1 to 4 may also satisfy the following conditions.

[0112] -5 <vdm-vds<5 (4)

[0113] Here,

[0114] vdm: the Abbe number of the lens element located closest to the magnification side of the field curvature correction lens group;

[0115] vds: Abbe number of the lens element located most on the reduction side in the field curvature correction lens group.

[0116] By satisfying condition (4), the change of magnification chromatic aberration caused by the movement of the field curvature correction lens group can be reduced. If it is below the lower limit of condition (4), the change of magnification chromatic aberration becomes larger when the field curvature correction action is performed. If it exceeds the upper limit, the off-axis magnification chromatic aberration deteriorates.

[0117] In addition, in the zoom lens system involved in Examples 1 to 4, the relay optical system Op may include, from the magnification side to the reduction side, a first relay lens group GL1 with negative optical power, a second relay lens group GL2 with positive optical power, a third relay lens group GL3 with positive optical power, and a fourth relay lens group GL4 with positive optical power, and when a zooming action is performed from the wide-angle end to the telephoto end, the magnification optical system Op and the first relay lens group GL1 are fixed, and the second relay lens group GL2, the third relay lens group GL3 and the fourth relay lens group GL4 move toward the magnification side.

[0118] According to such a structure, by arranging the lens group that moves during zooming in the relay optical system, the change of field curvature caused by zooming can be suppressed. In addition, the total length of the optical system can be reduced, and the zoom mechanism can be miniaturized and simplified.

[0119] Furthermore, in the zoom lens system according to Example 4, a zero-power element L4 having a refractive index greater than 1 may be arranged on the reduction side of the third lens element L3.

[0120] According to such a configuration, the outer diameter of the first lens element can be reduced.

[0121] Furthermore, the zoom lens system according to Example 4 may also satisfy the following conditions.

[0122] |tfp / fw|<1.1(5)

[0123] Here,

[0124] tfp: thickness of the zero optical power element L4;

[0125] fw: focal length of the entire optical system at the wide-angle end.

[0126] By satisfying condition (5), the relationship between the thickness tfp of the zero optical power element and the focal length fw of the entire optical system at the wide angle end can be optimized. If the upper limit of condition (5) is exceeded, the total length of the optical system increases.

[0127] (Numerical Example 1)

[0128] Regarding the zoom lens system of numerical embodiment 1 (corresponding to embodiment 1), the surface data is shown in Table 1, the various data are shown in Table 2, the single lens data is shown in Table 3, the zoom lens group data is shown in Table 4, the zoom lens group magnification is shown in Table 5, and the focus data is shown in Table 6 (unit is mm).

[0129] [Table 1]

[0130] Area data

[0131]

[0132]

[0133]

[0134] [Table 2] Various data

[0135]

[0136] [Table 3] Single lens data

[0137]

[0138]

[0139] [Table 4]

[0140] Zoom lens set data

[0141]

[0142] [Table 5]

[0143] Zoom lens ratio

[0144]

[0145] [Table 6]

[0146] Focus data

[0147]

[0148] (Numerical Example 2)

[0149] Regarding the zoom lens system of numerical embodiment 2 (corresponding to embodiment 2), the surface data is shown in Table 7, the various data is shown in Table 8, the single lens data is shown in Table 9, the zoom lens group data is shown in Table 10, the zoom lens group magnification is shown in Table 11, and the focus data is shown in Table 12 (unit is mm).

[0150] [Table 7]

[0151] Area data

[0152]

[0153]

[0154]

[0155] [Table 8] Various data

[0156]

[0157]

[0158] [Table 9]

[0159] Single lens data

[0160]

[0161] [Table 10]

[0162] Zoom lens set data

[0163]

[0164] [Table 11]

[0165] Zoom lens ratio

[0166]

[0167] [Table 12]

[0168] Focus data

[0169]

[0170] (Numerical Example 3)

[0171] Regarding the zoom lens system of numerical embodiment 3 (corresponding to embodiment 3), the surface data is shown in Table 13, the various data is shown in Table 14, the single lens data is shown in Table 15, the zoom lens group data is shown in Table 16, the zoom lens group magnification is shown in Table 17, and the focus data is shown in Table 18 (unit: mm).

[0172] [Table 13]

[0173] Area data

[0174]

[0175]

[0176] [Table 14] Various data

[0177]

[0178] [Table 15] Single lens data

[0179]

[0180]

[0181] [Table 16]

[0182] Zoom lens set data

[0183]

[0184] [Table 17]

[0185] Zoom lens ratio

[0186]

[0187] [Table 18]

[0188] Focus data

[0189]

[0190]

[0191] (Numerical Example 4)

[0192] Regarding the zoom lens system of numerical embodiment 4 (corresponding to embodiment 4), the surface data is shown in Table 19, the various data is shown in Table 20, the single lens data is shown in Table 21, the zoom lens group data is shown in Table 22, the zoom lens group magnification is shown in Table 23, and the focus data is shown in Table 24 (unit is mm).

[0193] [Table 19]

[0194] Area data

[0195]

[0196]

[0197]

[0198] [Table 20] Various data

[0199]

[0200]

[0201] [Table 21] Single lens data

[0202]

[0203] [Table 22]

[0204] Zoom lens set data

[0205]

[0206] [Table 23]

[0207] Zoom lens ratio

[0208]

[0209] [Table 24]

[0210] Focus data

[0211]

[0212] The following Table 25 shows the corresponding values ​​of each condition (1) to (8) in each numerical example.

[0213] [Table 25]

[0214] condition Mathematical formula Example 1 Example 2 Example 3 Example 4 (1) f1 / f2 1.35 1.07 1.33 1.18 (2) (L1R2+L1R1) / (L1R2-L1R1) 3.34 2.69 3.24 3.35 (3) |L1f / fw| 8.47 6.09 8.31 8.05 (4) vdm-vds 2.90 - 2.90 2.90 (5) |tfp / fw| - - - 0.58

[0215] Table 26 below shows the values ​​of the variables of the conditions (1) to (5) in each numerical example.

[0216] [Table 26]

[0217] variable Example 1 Example 2 Example 3 Example 4 f1 37.4 32.2 37.4 37.5 f2 27.8 30.0 28.1 31.9 LLR 62.1 49.2 62.1 56.5 LLR2 115.0 107.5 117.5 104.6 L1f 138.7 99.3 136.2 131.2 f -16.4 -16.3 -16.4 -16.3 vdm 23.8 - 23.8 23.8 vds 20.9 - 20.9 20.9 tfp - - - 9.5

[0218] f1: focal length of the magnifying optical system;

[0219] f2: focal length of the relay optical system;

[0220] L1R1: the radius of curvature of the magnification-side surface of the first lens element;

[0221] L1R2: the curvature radius of the surface on the reduction side of the first lens element;

[0222] L1f: focal length of the first lens element;

[0223] fw: focal length of the entire optical system at the wide-angle end;

[0224] vdm: Abbe number of the lens element located most on the magnification side of the field curvature correction lens group;

[0225] vds: Abbe number of the lens element located most on the reduction side of the field curvature correction lens group;

[0226] tfp: thickness of the zero optical power element.

[0227] (Implementation Method 2)

[0228] Below, use Fig.21 Embodiment 2 of the present disclosure will be described. Fig.21 1 is a block diagram showing an example of an image projection device involved in the present disclosure. The image projection device 100 includes the optical system 1 disclosed in Embodiment 1, an image forming element 101, a light source 102, a control unit 110, etc. The image forming element 101 is composed of a liquid crystal, a DMD, etc., and generates an image projected onto a screen SR via the optical system 1. The light source 102 is composed of an LED (light emitting diode), a laser, etc., and supplies light to the image forming element 101. The control unit 110 is composed of a CPU or an MPU, etc., and controls the entire device and each component. The optical system 1 can also be configured as a replaceable lens that can be freely detachably installed relative to the image projection device 100. In this case, the device after the optical system 1 is removed from the image projection device 100 is an example of a main device.

[0229] The image projection device 100 described above can realize a wide-angle zoom function by using the optical system 1 according to the first embodiment, and can also achieve miniaturization and weight reduction of the device.

[0230] (Implementation 3)

[0231] Below, use Fig. 22 Embodiment 3 of the present disclosure will be described. Fig. 22 1 is a block diagram showing an example of an imaging device involved in the present disclosure. Regarding the imaging device 200, the imaging device 200 includes the optical system 1 disclosed in Implementation 1, an imaging element 201, a control unit 210, and the like. The imaging element 201 is composed of a CCD (charge coupled device) image sensor, a CMOS image sensor, and the like, receives an optical image of an object OBJ formed by the optical system 1 and converts it into an electrical image signal. The control unit 110 is composed of a CPU or an MPU, and the like, and controls the entire device and each component. The optical system 1 can also be configured as a replaceable lens that can be freely detachably installed relative to the imaging device 200. In this case, the device after the optical system 1 is removed from the imaging device 200 is an example of a main device.

[0232] The above-described imaging device 200 can realize a wide-angle zoom function by using the optical system 1 according to the first embodiment, and can achieve miniaturization and weight reduction of the device.

[0233] As described above, the embodiments have been described as disclosure of the technology in the present disclosure, and for this purpose, the drawings and detailed descriptions are provided.

[0234] Therefore, the components described in the drawings and detailed descriptions include not only components necessary for solving the problem, but also components not necessary for solving the problem in order to illustrate the above-mentioned technology. Therefore, these non-essential components should not be directly identified as essential just because they are described in the drawings or detailed descriptions.

[0235] In addition, the above-mentioned embodiments are for illustrating the technology in the present disclosure, and therefore various changes, substitutions, additions, omissions, etc. can be made within the scope of the claims or the scope of their equivalents.

[0236] Industrial Applicability

[0237] The present disclosure can be applied to image projection devices such as projectors and head-up displays, and imaging devices such as digital still cameras, digital video cameras, surveillance cameras in surveillance systems, web cameras, and vehicle-mounted cameras. In particular, the present disclosure can be applied to optical systems that require high image quality, such as projectors, digital still camera systems, and digital video camera systems.

Claims

1. An optical system having an intermediate imaging position conjugated to an enlargement conjugate point on an enlargement side and a reduction conjugate point on a reduction side, The optical system comprises: a magnifying optical system having a plurality of lens elements located at a position closer to the magnification side than the intermediate imaging position; and A relay optical system having a plurality of lens elements located at a position closer to the reduction side than the intermediate imaging position, The first lens element of the magnification optical system located closest to the magnification side has positive refractive power. The optical system satisfies the following condition (1): 0.9≤f1 / f2≤1.5 (1) Here, f1: focal length of the magnifying optical system; f2: focal length of the relay optical system.

2. The optical system according to claim 1, wherein: The optical system satisfies the following condition (2): 2.0<(L1R2+L1R1) / (L1R2-L1R1)<5.0 (2) Here, L1R1: the radius of curvature of the surface on the magnification side of the first lens element; L1R2: The curvature radius of the surface on the reduction side of the first lens element.

3. The optical system according to claim 1, wherein: The first lens element has a refractive index of 1.8 or more.

4. The optical system according to claim 1, wherein: The magnifying optical system includes, in order from the magnification side to the reduction side, the first lens element having positive refractive power, the second lens element having negative refractive power other than the first lens element, and the third lens element having negative refractive power.

5. The optical system according to claim 4, wherein: In the range from the magnification-side surface of the first lens element to the position where the most off-axis light ray intersects the optical axis of the magnification optical system, only the first lens element, the second lens element and the third lens element are arranged as optical elements having optical power.

6. The optical system according to claim 1, wherein: The surface shapes of the plurality of lens elements constituting the magnifying optical system and the plurality of lens elements constituting the relay optical system are spherical surfaces or flat surfaces.

7. The optical system according to claim 1, wherein: The optical system meets the following conditions: 5<|L1f / fw|<10 (3) Here, L1f: focal length of the first lens element; fw: focal length of the entire optical system at the wide-angle end.

8. The optical system according to claim 1, wherein: The magnifying optical system includes an image curvature correction lens group having positive power adjacent to the intermediate imaging position on the magnification side. During the field curvature correction operation, the field curvature correction lens group moves along the optical axis of the magnification optical system, and the lens element located on the magnification side of the field curvature correction lens group and the relay optical system are fixed.

9. The optical system according to claim 8, wherein: In the field curvature correction lens group, the lens element located most on the magnification side has negative refractive power, and the lens element located most on the reduction side has positive refractive power.

10. The optical system according to claim 9, wherein: The optical system meets the following conditions: -5<vdm-vds<5 (4) Here, vdm: the Abbe number of the lens element located closest to the magnification side of the field curvature correction lens group; vds: Abbe number of the lens element located most on the reduction side in the field curvature correction lens group.

11. The optical system according to claim 1, wherein: The relay optical system includes, from the magnification side to the reduction side, a first relay lens group with negative optical power, a second relay lens group with positive optical power, a third relay lens group with positive optical power, and a fourth relay lens group with positive optical power. When zooming from the wide-angle end to the telephoto end, the magnification optical system and the first relay lens group are fixed, and the second relay lens group, the third relay lens group, and the fourth relay lens group move toward the magnification side.

12. The optical system according to claim 4, wherein: A zero-power element having a refractive index greater than 1 is arranged on the reduction side of the third lens element.

13. The optical system according to claim 12, wherein: The optical system meets the following conditions: |tfp / fw|<1.1 (5) Here, tfp: thickness of the zero optical power element; fw: focal length of the entire optical system at the wide-angle end.

14. An image projection device comprising: The optical system of any one of claims 1 to 13; and The image forming element generates an image to be projected onto a screen via the optical system.

15. A camera device comprising: The optical system of any one of claims 1 to 13; and The imaging element receives the optical image formed by the optical system and converts it into an electrical image signal.

Images