Optical system, image projection device, and image pickup device

Abstract

The present disclosure relates to an optical system having, inside, an intermediate imaging position conjugate with a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, the optical system comprising: a magnification optical system located on a magnification side of the intermediate imaging position; and a relay optical system located on a reduction side of the intermediate imaging position, the relay optical system having a first lens group on the most magnification side, having two lens groups on a reduction side of the first lens group, having a negative lens group disposed between the two lens groups, and the two lens groups moving while the negative lens group is fixed during zooming.

Description

Technical Field

[0001] This disclosure relates to an optical system for forming an intermediate image. Furthermore, this disclosure relates to an image projection device and a camera device using such an optical system. Background Technology

[0002] Intermediate imaging optical systems have the advantage of achieving wide-angle projection of large images with short focal lengths, but they tend to increase in overall length. This increases the weight of the optical system, and when part of the optical system is mounted outside the main body of the image projection device, the torque acting on the center of gravity may cause the optical system to tilt relative to the main body, resulting in reduced optical performance.

[0003] To reduce the weight of the optical system, synthetic resin lenses are assumed to be used instead of glass lenses. Compared to glass, synthetic resin has a lower specific gravity but lower thermal conductivity and a higher coefficient of linear expansion. Therefore, while this allows for a lighter optical system, it also tends to cause localized temperature increases, thermal distortion, and increased optical aberrations, especially chromatic aberration. This tendency is particularly pronounced in high-brightness projection scenarios.

[0004] Patent Document 1 discloses a wide-angle imaging optical system in which the first lens L1a, closest to the magnification conjugate point, has the largest aperture. Both surfaces of the first lens L1a are aspherical, resulting in a very complex shape, thus suggesting the use of a synthetic resin lens. However, this complex aspherical shape is highly sensitive to thermal deformation, and significant degradation of optical aberrations due to temperature increases is expected.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-174633 Summary of the Invention

[0008] -The problem the invention aims to solve-

[0009] This disclosure provides an optical system capable of reducing the torque acting on the center of gravity and mitigating the effects of heat. Furthermore, this disclosure provides an image projection device and a camera device using this optical system.

[0010] -Methods for solving the problem-

[0011] One aspect of this disclosure is an optical system having internal intermediate imaging positions conjugate to both a magnification conjugate point on the magnification side and a reduction conjugate point on the reduction side, the optical system comprising:

[0012] The magnifying optical system is located further from the magnifying side than the intermediate imaging position; and

[0013] The relay optical system is located further away from the reduced-size side than the intermediate imaging position.

[0014] The relay optical system has a first lens group on the side closest to the magnification.

[0015] The relay optical system has two lens groups positioned further to the narrowing side than the first lens group.

[0016] The relay optical system has a negative lens group positioned between two lens groups.

[0017] During zooming, with the negative lens group fixed, the two lens groups move.

[0018] Furthermore, the image projection apparatus disclosed herein includes: the aforementioned optical system; and an image forming element for generating an image projected onto a screen via the optical system.

[0019] Furthermore, the camera device disclosed herein includes: the aforementioned optical system; and a camera element that receives light from the optical image formed by the optical system and converts it into an electrical image signal.

[0020] -Invention Effects-

[0021] The optical system disclosed herein reduces the torque acting on the center of gravity and mitigates the effects of heat. Therefore, stable optical performance can be maintained even when high-intensity light passes through the lens, such as in high-brightness projection. Attached Figure Description

[0022] Figure 1 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 1 at an object distance of 1065.7157 mm.

[0023] Figure 2 This is a configuration diagram of the wide-angle end of the zoom lens in Example 1 at an object distance of 1065.7157 mm.

[0024] Figure 3 This is a longitudinal aberration diagram of the zoom lens of Example 1 at an object distance of 1065.7157 mm.

[0025] Figure 4 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 2 at an object distance of 1065.7157 mm.

[0026] Figure 5 This is a configuration diagram of the wide-angle end of the zoom lens in Example 2 at an object distance of 1065.7157 mm.

[0027] Figure 6This is a longitudinal aberration diagram of the zoom lens in Example 2 at an object distance of 1065.7157 mm.

[0028] Figure 7 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 3 at an object distance of 1065.7157 mm.

[0029] Figure 8 This is a configuration diagram of the wide-angle end of the zoom lens in Example 3 at an object distance of 1065.7157 mm.

[0030] Figure 9 This is a longitudinal aberration diagram of the zoom lens of Example 3 at an object distance of 1065.7157 mm.

[0031] Figure 10 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 4 at an object distance of 1065.7157 mm.

[0032] Figure 11 This is a configuration diagram of the wide-angle end of the zoom lens in Example 4 at an object distance of 1065.7157 mm.

[0033] Figure 12 This is a longitudinal aberration diagram of the zoom lens in Example 4 at an object distance of 1065.7157 mm.

[0034] Figure 13 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 5 at an object distance of 1065.7157 mm.

[0035] Figure 14 This is a configuration diagram of the wide-angle end of the zoom lens in Example 5 at an object distance of 1065.7157 mm.

[0036] Figure 15 This is a longitudinal aberration diagram of the zoom lens of Example 5 at an object distance of 1065.7157 mm.

[0037] Figure 16 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens of Embodiment 6 at an object distance of 1065.7157 mm.

[0038] Figure 17 This is a configuration diagram of the wide-angle end of the zoom lens in Example 6 at an object distance of 1065.7157 mm.

[0039] Figure 18 This is a longitudinal aberration diagram of the zoom lens of Example 6 at an object distance of 1065.7157 mm.

[0040] Figure 19This is a block diagram illustrating an example of an image projection apparatus as described in this disclosure.

[0041] Figure 20 This is a block diagram illustrating an example of the camera device involved in this disclosure. Detailed Implementation

[0042] Hereinafter, the embodiments will be described in detail with appropriate reference to the accompanying drawings. Some unnecessary details may be omitted. For example, detailed descriptions of known matters or repetitive descriptions of substantially the same structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0043] Furthermore, the applicant has provided the accompanying drawings and the following description in order to enable those skilled in the art to fully understand this disclosure, but these are not intended to limit the subject matter of the claims.

[0044] Hereinafter, various embodiments of the optical system disclosed herein will be described. In each embodiment, the optical system is described as being used in a projector (an example of an image projection device) to project an image light of an original image S, which is spatially modulated by an image forming element such as a liquid crystal or a DMD (digital micromirror device), onto a screen based on an image signal. That is, the optical system disclosed herein can be used to enlarge and project an original image S, which is disposed on an image forming element disposed on a reduction side, onto a screen by arranging a screen (not shown) on an extension line of the magnification side.

[0045] Furthermore, the optical system disclosed herein can also be used to focus light emitted from an object located on the extension line of the magnification side and form an optical image of the object on the imaging surface of the imaging element disposed on the reduction side.

[0046] (Implementation Method 1)

[0047] The following uses Figures 1 to 15 The first embodiment of this disclosure will now be described. Here, as an example of an optical system, a zoom lens system will be described.

[0048] Figure 1 , Figure 4 , Figure 7 , Figure 10 , Figure 13 , Figure 16 This is a diagram showing the optical path configuration at the wide-angle end of the zoom lens system involved in Examples 1 to 6, at a distance of 1065.7157 mm from the object. Figure 2 , Figure 5 , Figure 8 , Figure 11 , Figure 14 , Figure 17This is a configuration diagram of the wide-angle end of the zoom lens system involved in Examples 1 to 6 at an object distance of 1065.7157 mm. Figure 2 of (a), Figure 5 of (a), Figure 8 of (a), Figure 11 of (a), Figure 14 of (a), Figure 17 (a) shows the lens configuration at the wide-angle end of the zoom lens system. Figure 2 (b) Figure 5 (b) Figure 8 (b) Figure 11 (b) Figure 14 (b) Figure 17 (b) represents the lens configuration at the middle position of the zoom lens system. Figure 2 (c) Figure 5 (c) Figure 8 (c) Figure 11 (c) of 14 (c) Figure 17 (c) represents the lens configuration at the telephoto end of the zoom lens system.

[0049] The wide-angle end represents the shortest focal length (fw) of the entire system. The intermediate position represents the focal length between the wide-angle and telephoto ends. The telephoto end represents the longest focal length (ft) of the entire system. Based on the focal lengths fw and ft at the wide-angle and telephoto ends, the focal length fm at the intermediate position is defined as √(fw × ft).

[0050] The zoom lens system described in Example 1 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G4. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has positive optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens elements L16 to L18, with surfaces 31 to 36. Lens group G3 has negative optical power and includes lens elements L19 to L22, with surfaces 37 to 45. The fourth lens group G4 has positive optical power and includes lens elements L23 to L25, and includes surfaces 46 to 51. Optical element P includes surfaces 52 to 53.

[0051] The zoom lens system involved in Example 2 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G5. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has positive optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens elements L16 to L18, with surfaces 31 to 36. Lens group G3 has negative optical power and includes lens elements L19 to L22, with surfaces 37 to 45. Lens group G4 has positive optical power and includes lens element L23 (23rd lens element), including surfaces 46 and 47. Lens group G5 has positive optical power and includes lens elements L24 (24th lens element), L25 (25th lens element), and L26 (25th lens element), including surfaces 48 and 51. Optical element P includes surfaces 52 and 53.

[0052] The zoom lens system described in Example 3 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G6. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has positive optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens elements L16 to L18, with surfaces 31 to 36. Lens group G3 has negative optical power and includes lens elements L19 to L22, with surfaces 37 to 45. Lens group G4 has positive optical power and includes lens element L23, with surfaces 46 and 47. Lens group G5 has negative optical power and includes lens element L24, with surfaces 48 and 49. Lens group G6 has positive optical power and includes lens element L2, with surfaces 50 and 51. Optical element P includes surfaces 52 and 53.

[0053] The zoom lens system described in Example 4 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G6. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has positive optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens elements L16 to L17, with surfaces 31 to 34. Lens group G3 has positive optical power and includes lens element L18, with surfaces 35 to 36. Lens group G4 has negative optical power and includes lens elements L19 (19th) to L22 (22nd), with surfaces 37 to 45. Lens group G4 has positive optical power and includes lens element L23 (23rd), with surfaces 46 to 47. Lens group G6 has positive optical power and includes lens element L25 (24th), with surfaces 48 to 51. Optical element P includes surfaces 52 to 53.

[0054] The zoom lens system described in Example 5 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G8. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has positive optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens element L16, with surfaces 31 to 32. Lens group G3 has negative optical power and includes lens element L17, with surfaces 33 to 34. Lens group G4 has positive optical power and includes lens element L18 (18th lens element), including surfaces 35 to 36. Lens group G5 has negative optical power and includes lens elements L19 to L22 (22nd lens element), including surfaces 37 to 45. Lens group G6 has positive optical power and includes lens element L23 (23rd lens element), including surfaces 46 to 47. Lens group G7 has negative optical power and includes lens element L24 (24th lens element), including surfaces 48 to 49. Lens group G8 has positive optical power and includes lens element L25 (25th lens element), including surfaces 50 to 51. Optical element P includes surfaces 52 to 53.

[0055] The zoom lens system described in Example 6 includes a magnifying optical system Op, a relay optical system Ol, and an optical element P. The relay optical system Ol includes lens groups G1 to G6. The magnifying optical system Op includes lens elements L1 to L12, with surfaces 1 to 24 (refer to the numerical examples described later). The relay optical system Ol includes lens elements L13 to L25, with surfaces 25 to 51. Lens group G1 has negative optical power and includes lens elements L13 to L15, with surfaces 25 to 30. Lens group G2 has positive optical power and includes lens elements L16 to L18, with surfaces 31 to 36. Lens group G3 has positive optical power and includes lens element L19, with surfaces 37 to 38. Lens group G4 has negative optical power, including the aperture and lens element L20 (20th lens), and includes surfaces 39 to 41. Lens group G5 has negative optical power, including lens elements L21 (21st lens) to L22 (22nd lens), and includes surfaces 42 to 45. Lens group G6 has positive optical power, including lens elements L23 (23rd lens) to L25 (25th lens), and includes surfaces 46 to 51. Optical element P includes surfaces 52 to 53.

[0056] Figure 2 , Figure 5 , Figure 8 , Figure 11 , Figure 14 , Figure 17 The arrows on the broken lines between Figures (a) and (b) are straight lines drawn from the top of the figures, connecting the positions of the first lens group G1 to the eighth lens group G8 in the wide-angle, intermediate, and telephoto positions, respectively. The connections between the wide-angle and intermediate positions, and between the intermediate and telephoto positions, are simply straight lines, unlike the actual movement of each lens group G1 to G8. Furthermore, the symbols (+) and (-) assigned to each lens group G1 to G8 indicate the sign of its optical power.

[0057] The zoom lens system described in Examples 1 to 6 may also include, as needed, a focusing adjustment lens group that adjusts the focus when the object distance changes, and an image plane curvature correction lens group that corrects image plane curvature aberration after the focusing adjustment lens group has performed the focusing adjustment.

[0058] In each figure, the imaging position on the magnified side (i.e., the magnified conjugate point) is located on the left, and the imaging position on the reduced side (i.e., the reduced conjugate point) is located on the right. Furthermore, in each figure, the straight line closest to the reduced side represents the position of the original image S, and the optical element P is located on the magnified side of the original image S. The optical element P represents optical elements such as prisms for color decomposition and color synthesis, optical filters, parallel plate glass, crystal low-pass filters, and infrared cut-off filters.

[0059] The zoom lens systems described in Examples 1 to 6 have an intermediate imaging position MI internally, which is conjugate to both the magnification conjugate point on the magnification side and the reduction conjugate point on the reduction side. Furthermore, in each figure, a magnifying optical system Op is positioned further to the magnification side than the intermediate imaging position MI, and a relay optical system Ol is positioned further to the reduction side than the intermediate imaging position MI.

[0060] In the zoom lens systems described in Examples 1-6, multiple air gaps exist between the first lens element L1 to the 25th lens element L25 and the optical element P. The magnifying optical system Op has the longest air gap along the optical axis within the magnifying optical system. For example, as... Figure 2 , Figure 5 , Figure 8 , Figure 11 , Figure 14 , Figure 17 As shown, the longest air gap exists between the 9th lens element L9 and the 10th lens element L10. The magnifying optical system Op includes: a front group Opf located on the magnification side further than the longest air gap, and a rear group Opr located on the reduction side further than the longest air gap. The front group Opf and the rear group Opr may have one or more lens elements.

[0061] Figure 3 , Figure 6 , Figure 9 , Figure 12 , Figure 15 , Figure 18 These are longitudinal aberration diagrams of the zoom lens system described in Examples 1-6 at an object distance of 1065.7157 mm. In each diagram, (a), (b), and (c) represent the longitudinal aberration diagrams at the wide-angle end, the middle position, and the telephoto end of the zoom lens system.

[0062] The vertical aberration diagrams, from left to right, represent spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion aberration (DIS (%)). In the spherical aberration diagram, the vertical axis represents the pupil height; the solid line is the d-line, the short dashed line is the F-line, and the long dashed line is the C-line. In the astigmatism diagram, the vertical axis represents the image height; the solid line is the sagittal plane (shown as 's' in the diagram), and the dashed line is the meridional plane (shown as 'm' in the diagram). In the distortion aberration diagram, the vertical axis represents the image height. Furthermore, the distortion aberration diagram represents the distortion aberration for equidistant projections.

[0063] (Example 1)

[0064] like Figure 1 , Figure 2 As shown, the zoom lens system according to Embodiment 1 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes a first lens element L1 to a twelfth lens element L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0065] The front group Opf of the magnifying optical system Op includes, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L8 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L9 has a positive meniscus shape with its convex surface facing the reducing side.

[0066] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0067] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0068] The relay optical system Ol comprises, from the magnification side to the reduction side, a first lens group (L13-L15) with positive optical power, a second lens group (L16-L18) with positive optical power, a third lens group (L19-L22) with negative optical power, and a fourth lens group (L23-L25) with positive optical power. During zooming, the first and third lens groups are fixed, while the second and fourth lens groups are displaced along the optical axis. When zooming from the wide-angle end to the telephoto end, the second and fourth lens groups are displaced towards the magnification side.

[0069] In other words, the relay optical system Ol has: a first lens group (example of the first lens group) having positive optical power on the magnification side, and a third lens group (example of the negative lens group) disposed between the second and fourth lens groups (example of two lens groups) on the reduction side. When zooming, the third lens group is fixed, and the second and fourth lens groups move toward the magnification side.

[0070] An intermediate imaging position MI is located between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. An optical element P with zero optical power is positioned on the reduced-angle side of the relay optical system Ol.

[0071] (Example 2)

[0072] like Figure 4 , Figure 5 As shown, the zoom lens system according to Embodiment 2 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes a first lens element L1 to a twelfth lens element L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0073] The front group Opf of the magnifying optical system Op comprises, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L8 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L9 has a positive meniscus shape with its convex surface facing the reducing side.

[0074] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0075] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0076] The relay optical system Ol comprises, from the magnification side to the reduction side, the following lens groups: a first lens group (L13-L15) with positive optical power, a second lens group (L16-L18) with positive optical power, a third lens group (L19-L22) with negative optical power, a fourth lens group (L23) with positive optical power, and a fifth lens group (L24-L25) with positive optical power. During zooming, the first, third, and fifth lens groups are fixed, while the second and fourth lens groups are displaced along the optical axis. When zooming from the wide-angle end to the telephoto end, the second and fourth lens groups are displaced towards the magnification side.

[0077] In other words, the relay optical system Ol has: a first lens group (example of the first lens group) having positive optical power on the magnification side, and a third lens group (example of the negative lens group) disposed between the second and fourth lens groups (example of two lens groups) on the reduction side. When zooming, the third lens group is fixed, and the second and fourth lens groups move toward the magnification side.

[0078] An intermediate imaging position MI exists between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. On the reduced-angle side of the relay optical system Ol, an optical element P with zero optical power is positioned.

[0079] (Example 3)

[0080] like Figure 7 , Figure 8 As shown, the zoom lens system according to Embodiment 3 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes a first lens element L1 to a twelfth lens element L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0081] The front group Opf of the magnifying optical system Op comprises, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L8 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L9 has a positive meniscus shape with its convex surface facing the reducing side.

[0082] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0083] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0084] The relay optical system Ol comprises, from the magnification side to the reduction side, the following lens groups: a first lens group (L13-L15) with positive optical power, a second lens group (L16-L18) with positive optical power, a third lens group (L19-L22) with negative optical power, a fourth lens group (L23) with positive optical power, a fifth lens group (L24) with negative optical power, and a sixth lens group (L25) with positive optical power. During zooming, the first, third, and sixth lens groups are fixed, while the second, fourth, and fifth lens groups are displaced along the optical axis. When zooming from the wide-angle end to the telephoto end, the second, fourth, and fifth lens groups are displaced towards the magnification side.

[0085] In other words, the relay optical system Ol has: a first lens group (an example of the first lens group) having positive optical power on the magnification side, and a third lens group (an example of a negative lens group) positioned between the second and fourth lens groups (an example of two lens groups) on the reduction side. During zooming, with the third lens group fixed, the second and fourth lens groups move towards the magnification side. The relay optical system Ol also has a fifth lens group (an example of other negative lens groups), and the negative optical power of the third lens group is smaller than that of the fifth lens group.

[0086] An intermediate imaging position MI exists between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. On the reduced-angle side of the relay optical system Ol, an optical element P with zero optical power is positioned.

[0087] (Example 4)

[0088] like Figure 10 , Figure 11 As shown, the zoom lens system according to Embodiment 4 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes first lens elements L1 to twelfth lens elements L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0089] The front group Opf of the magnifying optical system Op comprises, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a biconcave shape. Lens element L8 has a biconvex shape. Lens element L9 has a positive meniscus shape with its convex surface facing the reducing side.

[0090] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0091] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0092] The relay optical system Ol comprises, from the magnification side to the reduction side, the following lens groups: a first lens group (L13-L15) with positive optical power, a second lens group (L16-L17) with positive optical power, a third lens group (L18) with positive optical power, a fourth lens group (L19-L22) with negative optical power, a fifth lens group (L23) with positive optical power, and a sixth lens group (L24-L25) with positive optical power. During zooming, the first, fourth, and sixth lens groups are fixed, while the second, third, and fifth lens groups are displaced along the optical axis. When zooming from the wide-angle end to the telephoto end, the second, third, and fifth lens groups are displaced towards the magnification side.

[0093] In other words, the relay optical system Ol has: a first lens group (example of the first lens group) having positive optical power on the magnification side, and a fourth lens group (example of the negative lens group) disposed between the third lens group and the fifth lens group (example of two lens groups) on the reduction side. When zooming, the third lens group and the fifth lens group move toward the magnification side while the fourth lens group is fixed.

[0094] An intermediate imaging position MI is located between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. An optical element P with zero optical power is positioned on the reduced-angle side of the relay optical system Ol.

[0095] (Example 5)

[0096] like Figure 13 , Figure 14As shown, the zoom lens system according to Embodiment 5 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes a first lens element L1 to a twelfth lens element L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0097] The front group Opf of the magnifying optical system Op includes, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a biconcave shape. Lens element L8 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L9 has a biconvex shape.

[0098] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0099] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0100] The relay optical system Ol comprises, from the magnification side to the reduction side, the following lens groups: a first lens group (L13-L15) with positive optical power, a second lens group (L16) with positive optical power, a third lens group (L17) with negative optical power, a fourth lens group (L18) with positive optical power, a fifth lens group (L19-L22) with negative optical power, a sixth lens group (L23) with positive optical power, a seventh lens group (L24) with negative optical power, and an eighth lens group (L25) with positive optical power. During zooming, the first, fifth, and eighth lens groups are fixed, while the second, third, fourth, sixth, and seventh lens groups are displaced along the optical axis. When zooming from the wide-angle end to the telephoto end, the second, third, fourth, sixth, and seventh lens groups are displaced towards the magnification side.

[0101] In other words, the relay optical system Ol has: a first lens group (an example of the first lens group) having positive optical power on the magnification side, and a fifth lens group (an example of a negative lens group) disposed between the fourth and sixth lens groups (an example of two lens groups) on the reduction side. During zooming, with the fifth lens group fixed, the fourth and sixth lens groups move towards the magnification side. The relay optical system Ol also has a third lens group and a seventh lens group (an example of other negative lens groups), with the negative optical power of the fifth lens group being smaller than that of the third and seventh lens groups.

[0102] An intermediate imaging position MI is located between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. An optical element P with zero optical power is positioned on the reduced-angle side of the relay optical system Ol.

[0103] (Example 6)

[0104] like Figure 16 , Figure 17 As shown, the zoom lens system according to Embodiment 6 includes a magnifying optical system Op and a relay optical system Ol. The magnifying optical system Op includes a first lens element L1 to a twelfth lens element L12. The magnifying optical system Op includes a front group Opf and a rear group Opr.

[0105] The front group Opf of the magnifying optical system Op includes, from the magnifying side to the reducing side, lens elements L1 to L9 in sequence. Lens element L1 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L2 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L3 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L4 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L5 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L6 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L7 has a biconcave shape. Lens element L8 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L9 has a biconvex shape.

[0106] The rear group Opr of the magnifying optical system Op includes, from the magnifying side to the reducing side, 10th lens element L10 to 12th lens element L12. The 10th lens element L10 has a biconvex shape. The 11th lens element L11 has a positive meniscus shape with its convex surface facing the magnifying side. The 12th lens element L12 has a negative meniscus shape with its convex surface facing the magnifying side.

[0107] The relay optical system Ol comprises, sequentially from the magnifying side to the reducing side, lens elements L13 to L25, numbered 13 to 25. Lens element L13 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L14 has a biconcave shape. Lens element L15 has a positive meniscus shape with its convex surface facing the reducing side. Lens element L16 has a biconvex shape. Lens element L17 has a negative meniscus shape with its convex surface facing the reducing side. Lens element L18 has a biconvex shape. Lens element L19 has a positive meniscus shape with its convex surface facing the magnifying side. Lens element L20 has a negative meniscus shape with its convex surface facing the magnifying side. Lens element L21 has a biconcave shape. Lens element L22 has a biconvex shape. Lens element L23 has a biconvex shape. Lens element L24 has a negative meniscus shape with its convex surface facing the magnifying side. The 25th lens element L25 has a biconvex shape.

[0108] The relay optical system Ol comprises, from the magnification side to the reduction side, the following lens groups in sequence: a first lens group (L13-L15) with negative optical power, a second lens group (L16-L18) with positive optical power, a third lens group (L19) with positive optical power, a fourth lens group (L20) with negative optical power, a fifth lens group (L21-L22) with negative optical power, and a sixth lens group (L23-L25) with positive optical power. During zooming, the first and fourth lens groups are fixed, while the second, third, fifth, and sixth lens groups shift along the optical axis. When zooming from the wide-angle end to the telephoto end, the second, fifth, and sixth lens groups shift towards the magnification side, and the third lens group shifts towards the reduction side.

[0109] In other words, the relay optical system Ol has: a first lens group (an example of the first lens group) having negative optical power on the magnification side, and a fourth lens group (an example of a negative lens group) disposed between the third and fifth lens groups (an example of two lens groups) on the reduction side. During zooming, with the fourth lens group fixed, the third lens group moves towards the reduction side, and the fifth lens group moves towards the magnification side. The relay optical system Ol also has a fourth lens group and a fifth lens group (an example of other negative lens groups), wherein the negative optical power of the fourth lens group is smaller than that of the fifth lens group.

[0110] An intermediate imaging position MI is located between the 12th lens element L12 and the 13th lens element L13. Furthermore, an aperture A is positioned between the 19th lens element L19 and the 20th lens element L20. An optical element P with zero optical power is positioned on the reduced-angle side of the relay optical system Ol.

[0111] Furthermore, the zoom lens system involved in Examples 1 to 6 is not only a lens element with optical power, but may also include optical elements such as mirrors, apertures, masks, glass covers, filters, prisms, wavelength plates, polarizing elements, etc., which have zero or substantially zero optical power.

[0112] Next, the conditions that the zoom lens system involved in this embodiment can satisfy will be explained. Furthermore, multiple conditions are specified for the zoom lens system involved in each embodiment, but all of these conditions can be satisfied, or individual conditions can be satisfied to obtain corresponding effects.

[0113] The zoom lens system described in Examples 1-6 is an optical system having an intermediate imaging position internally conjugate to both the magnification conjugate point on the magnification side and the reduction conjugate point on the reduction side. The optical system comprises: a magnifying optical system located closer to the magnification side than the intermediate imaging position, and a relay optical system located closer to the reduction side than the intermediate imaging position. The relay optical system comprises: a first lens group having positive optical power closest to the magnification side, two lens groups located closer to the reduction side than the first lens group, and a negative lens group disposed between the two lens groups. During zooming, the negative lens group is fixed while the two lens groups move.

[0114] Based on this structure, even when the lens is wide-angled, the effective diameter of the lens can be reduced, and the weight of the lens can be reduced. In addition, the zoom mechanism can be easily constructed, thus making the mechanism components lighter and the lens as a whole lighter.

[0115] Furthermore, in the zoom lens systems described in Examples 1 to 6, the first lens group and the magnifying optical system are fixed during zooming.

[0116] With this structure, by positioning the zoom mechanism further to the reduction side than the central imaging position, the zoom action mechanism, such as a cam or motor, can be mounted on the reduction side. This allows the lens barrel's center of gravity to shift towards the reduction side.

[0117] Furthermore, in the zoom lens systems described in Examples 1 to 6, the relay optical system also has other negative lens groups, the negative optical power of which is smaller than that of the other negative lens groups.

[0118] Based on this structure, aberration variation can be reduced during zooming, and good performance can be obtained throughout the entire zoom range.

[0119] Furthermore, in the zoom lens systems described in Examples 1 to 6, the negative lens group has an aperture.

[0120] Based on this structure, aberration variation can be reduced during zooming, and good performance can be obtained throughout the entire zoom range.

[0121] Furthermore, in the zoom lens systems described in Examples 1 to 6, the lens closest to the reduction side of the magnifying optical system is a negative lens.

[0122] This structure allows for a reduction in the effective diameter of the lens that is close to the center of the image, enabling the lens to be made lighter.

[0123] Furthermore, in the zoom lens systems described in Examples 1 to 6, the lens closest to the magnification side of the relay optical system is a positive lens.

[0124] This structure allows for a reduction in the effective diameter of the lens that is close to the center of the image, enabling the lens to be made lighter.

[0125] Furthermore, the zoom lens systems described in Examples 1 to 6 can also satisfy condition (1).

[0126] 0.1 < fp / fr < 0.5 ···(1)

[0127] here,

[0128] fp: Focal length of the magnifying optical system

[0129] fr: The focal length of the relay optical system at the wide-angle end.

[0130] Condition (1) is a conditional expression used to define the relationship between the combined focal length of the magnifying optical system and the relay optical system. By satisfying this condition, a wide-angle optical system with a small lens diameter can be achieved. If the value is lower than the lower limit of condition (1), the effective diameter of the lens element located further to the magnification side than the intermediate imaging position and with the second closest positive focal power to the magnification side from the intermediate imaging position becomes too large, and the lens becomes heavy. Conversely, if the value exceeds the upper limit, the effective diameter of the lens located on the magnification side becomes too large, and the lens becomes heavy.

[0131] In addition to condition (1), even more favorable results can be obtained by satisfying the following condition (1A).

[0132] 0.15 < fp / fr < 0.30...(1A)

[0133] Furthermore, the zoom lens systems described in Examples 1 to 6 can also satisfy condition (2).

[0134] 100<|fr1 / fw|<1000···(2)

[0135] here,

[0136] fr1: Focal length of the first lens group

[0137] fw: The focal length of the entire system at the wide-angle end.

[0138] Condition (2) is a conditional expression used to define the relationship between the focal length of the first lens group and the focal length of the entire system at the wide-angle end. By satisfying this condition, a wide-angle optical system with a small lens diameter can be achieved. If the upper limit of condition (2) is exceeded, the aperture of the first lens group becomes too large, and the lens becomes heavy. Conversely, if the lower limit is exceeded, the aperture of the rear group of the magnifying optical system becomes too large, and the lens becomes heavy.

[0139] In addition to condition (2), the following condition (2A) is also satisfied, which will result in a more favorable effect.

[0140] 150<|fr1 / fw|<700···(2A)

[0141] Furthermore, the zoom lens systems described in Examples 1 to 6 can also satisfy condition (3).

[0142] 5 < frn / fw < 50 ···(3)

[0143] here,

[0144] frn: Focal length of the negative lens group

[0145] fw: The focal length of the entire system at the wide-angle end.

[0146] Condition (3) is a conditional expression used to define the relationship between the focal length of the negative lens group and the focal length of the entire system at the wide-angle end. By satisfying this condition, an optical system with a wide angle and a small lens diameter can be realized. If the upper limit of condition (3) is exceeded, the aperture of the negative lens group becomes too large, and the lens becomes heavy. Conversely, if the lower limit is exceeded, the aperture of the group closer to the reduction side than the negative lens group becomes too large, and the lens becomes heavy.

[0147] In addition to condition (3), the following condition (3A) can be met to obtain a more favorable effect.

[0148] 8 < frn / fw < 30 ···(3A)

[0149] In addition, in the zoom lens system involved in Examples 1 to 6, the magnifying optical system may have the longest air gap, with the longest air gap as the boundary, and have a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side, and satisfy conditions (4) and (5).

[0150] 6.5 < |Ts / fw| < 12.0···(4)

[0151] 3.0 < |Tpr / fw| < 8.0···(5)

[0152] here,

[0153] Ts: The longest air gap in the magnifying optical system.

[0154] fw: The focal length of the entire system.

[0155] Tpr: The distance from the surface of the rear group of the magnifying optical system to the center image.

[0156] Condition (4) is a conditional expression that specifies the relationship between the longest air gap within the magnifying optical system and the focal length of the entire system at the wide-angle end. By satisfying condition (4), the optical system can be widened. If it is below the lower limit of condition (4), the lens of the front group of the magnifying optical system becomes heavier. If it exceeds the upper limit of condition (4), the center of gravity of the entire optical system shifts towards the magnifying side. Furthermore, condition (5) is a conditional expression that specifies the relationship between the distance from the magnifying side surface of the rear group of the magnifying optical system to the intermediate image and the focal length of the entire system at the wide-angle end. By satisfying condition (5), the effect of condition (4) can be achieved.

[0157] In addition to conditions (4) and (5), at least one of the following conditions (4A) and (5A) is also satisfied, thereby obtaining a more favorable effect.

[0158] 6.5 < |Ts / fw| < 10.0...(4A)

[0159] 5.0 < |Tpr / fw| < 6.5...(5A)

[0160] The zoom lens systems described in Examples 1 to 6 can also satisfy the following condition (6).

[0161] 0.8 < Tp / Tr < 1.0...(6)

[0162] here,

[0163] Tp: The distance from the surface of the magnifying optical system closest to the magnification side to the intermediate imaging position.

[0164] Tr: The distance from the intermediate imaging position at the wide-angle end to the surface of the relay optical system closest to the narrowed side.

[0165] Condition (6) is a conditional expression that specifies the relationship between the distance from the surface closest to the magnification side of the magnifying optical system to the intermediate imaging position and the distance from the intermediate imaging position at the wide-angle end to the surface closest to the reduction side of the relay optical system. If the upper limit of condition (6) is exceeded, it is difficult to correct the image plane curvature. If the lower limit of condition (6) is exceeded, the center of gravity shifts towards the magnification side.

[0166] In addition to condition (6), the following condition (6A) is also satisfied, which will result in a more favorable effect.

[0167] 0.9 < Tp / Tr < 1.0...(6A)

[0168] In the zoom lens system involved in Examples 1 to 6, the magnifying optical system may have the longest air gap, with the longest air gap as the boundary, and there is a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side, and the peasant painting satisfies the following conditional expression (7).

[0169] 7 < |fpr / fw| < 12...(7)

[0170] here,

[0171] fpr: The focal length of the rear group of the magnifying optical system.

[0172] Condition (7) is a conditional expression that specifies the relationship between the focal length of the rear group of the magnifying optical system and the focal length of the entire system at the wide-angle end. If the upper limit of condition (7) is exceeded, the aperture of the rear group of the magnifying optical system becomes too large and the lens becomes heavy. If the lower limit of condition (7) is exceeded, the aperture of the front group of the magnifying optical system becomes too large and the lens becomes heavy.

[0173] In addition to condition (7), the following condition (7A) can be met to obtain a more favorable effect.

[0174] 9 < |fpr / fw| < 10...(7A)

[0175] In the zoom lens systems described in Examples 1 to 6, the magnifying optical system may have the longest air gap, with the longest air gap as the boundary, and may have a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side, and satisfy the following condition (8).

[0176] 2 < |fpf / fw| < 5...(8)

[0177] here,

[0178] fpf: The focal length of the front group of the magnifying optical system.

[0179] Condition (8) is a conditional expression that specifies the relationship between the focal length of the front group of the magnifying optical system and the focal length of the entire system at the wide-angle end. If the upper limit of condition (8) is exceeded, the aperture of the front group of the magnifying optical system becomes too large and the lens becomes too heavy. If the lower limit of condition (8) is exceeded, the aperture of the rear group of the magnifying optical system becomes too large and the lens becomes too heavy.

[0180] In addition to condition (8), the following condition (8A) is also satisfied, which will result in a more favorable effect.

[0181] 3 < |fpf / fw| < 4...(8A)

[0182] Furthermore, in the zoom lens systems described in Examples 1 to 6, a first lens element may be disposed on the magnifying side of the magnifying optical system. This first lens element has a first lens magnifying side facing the magnifying side and a first lens reducing side facing the reducing side.

[0183] The magnifying side and the reducing side of the first lens satisfy the following condition (9) within the range from r > 0 to the effective diameter.

[0184] dZ(r) / dr>0...(9)

[0185] here,

[0186] r: The distance from the vertex along the plane perpendicular to the optical axis of the optical system (r > 0).

[0187] Z(r): Sag of the face (Z=0 is set at the vertex (r=0), the shrinking lateral displacement relative to the vertex is set to the sign +, and the expanding lateral displacement is set to the sign -).

[0188] Condition (9) is a conditional expression that specifies the first derivative dZ(r) / dr of the droop Z(r) on the opposite side as positive. By satisfying condition (9), even when local heat is generated in the first lens element, the shape change based on thermal expansion is such that the magnifying side and the reducing side of the first lens are the same. As a result, image plane curvature and astigmatism can be suppressed.

[0189] Furthermore, in the zoom lens systems described in Examples 1 to 6, the first lens element may also be made of synthetic resin.

[0190] Based on this structure, the first lens element can be made to have a large aperture, and therefore, by making it made of synthetic resin, the lens can be made lightweight.

[0191] Furthermore, among the multiple lens elements of the zoom lens system involved in Examples 1 to 6, all lens elements that satisfy condition (10) may satisfy condition (11), or one of the multiple lens elements may not satisfy either condition (10) or (11).

[0192] |ym / (fw·tan(ωm))|<3.0...(10)

[0193] Tg>300℃...(11)

[0194] here,

[0195] ωm: The maximum half-field angle at the wide-angle end.

[0196] ym: The height at which the outermost principal ray at the telescope passes through the lens surface.

[0197] Tg: Glass transition point of the lens material.

[0198] Condition (10) is a conditional expression that specifies the relationship between the height of the outermost principal ray passing through the lens surface at the telephoto end, the focal length of the entire system at the wide-angle end, and the maximum half field of view at the wide-angle end. Condition (11) is a conditional expression that specifies the glass transition point of the lens material. By satisfying both conditions (10) and (11), lens degradation can be prevented when high-intensity light passes through the lens. In addition, ym is calculated based on the surface with the lower height passing through the magnifying and reducing sides of the lens. Furthermore, in areas where condition (10) is not satisfied, to minimize the impact of heat, the range of glass materials that can be selected can be broadened, and materials with a glass transition point Tg that does not satisfy the lens material can be chosen. As a result, materials with a low glass transition point Tg, such as resin, can be selected, enabling lightweight construction.

[0199] Furthermore, the zoom lens systems described in Examples 1 to 6 can also satisfy the following conditional expression (12).

[0200] ωm>65°...(12)

[0201] here,

[0202] ωm: The maximum half field of view at the wide-angle end.

[0203] Condition (12) is a conditional expression that specifies the maximum half field of view at the wide-angle end. By satisfying condition (12), the working distance (action distance) can be shortened.

[0204] Furthermore, the zoom lens systems described in Examples 1 to 6 can also satisfy the following conditional expression (13).

[0205] -1.5<(L1R1+L1R2) / (L1R2-L1R1)<-0.9...(13)

[0206] here,

[0207] L1R1: The central radius of curvature of the lens's magnifying side closest to the magnifying side.

[0208] L1R2: The central radius of curvature of the lens on the magnifying side is reduced.

[0209] Condition (13) is a conditional expression that specifies the shape factor of the first lens element located on the magnifying side in a magnifying optical system. By satisfying condition (13), image plane curvature and aberration can be corrected, and the effective diameter of the lens can be reduced. If the value is below the lower limit of condition (13), the correction of image plane curvature and aberration becomes insufficient. Furthermore, if the value exceeds the upper limit, the effective diameter of the lens located on the reducing side becomes larger.

[0210] In addition to condition (13), the following condition (13A) is also satisfied, thereby obtaining a more favorable effect.

[0211] -1.2<(L1R1+L1R2) / (L1R2-L1R1)<-1.07...(13A)

[0212] The zoom optical system described in Examples 1 to 6 may also have a positive optical power in the rear group that is closest to the magnification side, and move towards the magnification side when zooming from the wide-angle end to the telephoto end.

[0213] This structure can reduce aberration variations during zooming.

[0214] The zoom optical systems described in Examples 1 to 6 can also have positive optical power in the magnification side group adjacent to the front group and positive optical power in the group adjacent to the reduction side.

[0215] This structure can reduce aberration variations during zooming.

[0216] As described above, several embodiments have been illustrated as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can also be applied to implementations with appropriate modifications, substitutions, additions, omissions, etc.

[0217] The following describes numerical embodiments of the zoom lens system described in Examples 1 to 6. In these numerical embodiments, all lengths are in mm and all field of view are in degrees. Furthermore, in these numerical embodiments, r is the radius of curvature, d is the surface spacing, nd is the refractive index relative to the d-line, and vd is the Abbe number relative to the d-line. Additionally, in these numerical embodiments, surfaces marked with an asterisk (*) are aspherical surfaces, and the shape of an aspherical surface is defined by the following formula.

[0218] [Formula 1]

[0219]

[0220] here,

[0221] Z: The distance from a point on the aspherical surface at a height h from the optical axis to the tangent plane at the vertex of the aspherical surface.

[0222] h: distance from the optical axis

[0223] r: Vertex radius of curvature

[0224] κ: Conic constant,

[0225] An: The aspheric coefficient of degree n.

[0226] (Numerical Example 1)

[0227] 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, and the single lens data are shown in Table 3 (unit is mm).

[0228] [Table 1]

[0229]

[0230]

[0231]

[0232] Aspherical data

[0233] Page 1

[0234] K=0.00000E+00,A3=1.28353E-04,A4=-2.64195E-07,A5=-6.74969E-08

[0235] A6=1.81712E-09, A7=-1.58164E-11, A8=-6.22311E-14, A9=2.06740E-15

[0236] A10 = -1.04375E-17

[0237] Page 2

[0238] K=-8.26520E-01,A3=1.67017E-04,A4=-3.90151E-06,A5=4.01101E-09

[0239] A6=8.36718E-11, A7=-1.92652E-12, A8=3.11135E-14, A9=6.71471E-16

[0240] A10 = -8.69102E-18

[0241] Page 9

[0242] K=0.00000E+00,A3=0.00000E+00,A4=-2.79259E-05,A5=0.00000E+00

[0243] A6=-9.86305E-08, A7=0.00000E+00, A8=-4.35015E-11, A9=0.00000E+00

[0244] A10 = -354848E-12

[0245] Page 10

[0246] K=0.00000E+00,A3=0.00000E+00,A4=6.83358E-06,A5=0.00000E+00

[0247] A6=5.05887E-09, A7=0.00000E+00, A8=4.34142E-12, A9=0.00000E+00

[0248] A10 = 0.00000E + 00

[0249] [Table 2]

[0250]

[0251] [Table 3]

[0252]

[0253]

[0254] (Numerical Example 2)

[0255] Regarding the zoom lens system of numerical embodiment 2 (corresponding to embodiment 2), the surface data is shown in Table 4, the various data are shown in Table 5, and the single lens data is shown in Table 6 (the unit is mm).

[0256] [Table 4]

[0257]

[0258]

[0259]

[0260] Aspherical data

[0261] Page 1

[0262] K=0.00000E+00, A3=1.28839E-04, A4=-3.08330E-07, A5=-6.71661E-08

[0263] A6=1.82141E-09, A7=-1.58537E-11, A8=-6.25886E-14, A9=2.06822E-15

[0264] A10=-1.04113E-17

[0265] 2nd surface

[0266] K=-8.31900E-01, A3=1.67819E-04, A4=-3.91209E-06, A5=3.98957E-09

[0267] A6=8.43543E-11, A7=-1.91614E-12, A8=3.12599E-14, A9=6.71655E-16

[0268] A10=-8.70014E-18

[0269] 9th surface

[0270] K=0.00000E+00, A3=0.00000E+00, A4=-2.77656E-05, A5=0.00000E+00

[0271] A6=-1.04848E-07, A7=0.00000E+00, A8=-1.16343E-11, A9=0.00000E+00

[0272] A10=-3.81206E-12

[0273] 10th surface

[0274] K=0.00000E+00, A3=0.00000E+00, A4=6.68590E-06, A5=0.00000E+00

[0275] A6=4.30475E-09, A7=0.00000E+00, A8=5.04148E-12, A9=0.00000E+00

[0276] A10=0.00000E+00

[0277] [Table 5]

[0278]

[0279]

[0280] [Table 6]

[0281]

[0282]

[0283] (Numerical Example 3)

[0284] Regarding the zoom lens system of numerical embodiment 3 (corresponding to embodiment 3), the surface data is shown in Table 7, the various data are shown in Table 8, and the single lens data is shown in Table 9 (unit is mm).

[0285] [Table 7]

[0286]

[0287]

[0288]

[0289] Aspherical data

[0290] Page 1

[0291] K=0.00000E+00,A3=1.27352E-04,A4=-2.46395E-07,A5=-6.78194E-08

[0292] A6=1.82353E-09, A7=-1.58698E-11, A8=-6.23368E-14, A9=2.06906E-15

[0293] A10 = -1.04258E-17

[0294] Page 2

[0295] K=-8.34168E-01,A3=1.66154E-04,A4=-3.92942E-06,A5=3.98305E-09

[0296] A6=8.75484E-11, A7=-1.87356E-12, A8=3.13986E-14, A9=6.69332E-16

[0297] A10 = -8.78444E-18

[0298] Page 9

[0299] K=0.00000E+00,A3=0.00000E+00,A4=-2.59408E-05,A5=0.00000E+00

[0300] A6=-1.01204E-07, A7=0.00000E+00, A8=1.03376E-11, A9=0.00000E+00

[0301] A10 = -3.68227E-12

[0302] Page 10

[0303] K=0.00000E+00,A3=0.00000E+00,A4=6.01465E-06,A5=0.00000E+00

[0304] A6=4.28522E-09, A7=0.00000E+00, A8=4.82571E-12, A9=0.00000E+00

[0305] A10 = 0.00000E + 00

[0306] [Table 8]

[0307]

[0308]

[0309] [Table 9]

[0310]

[0311]

[0312] (Numerical Example 4)

[0313] Regarding the zoom lens system of numerical embodiment 4 (corresponding to embodiment 4), the surface data is shown in Table 10, various data are shown in Table 11, and single lens data are shown in Table 12 (unit is mm).

[0314] [Table 10]

[0315]

[0316]

[0317]

[0318] Aspherical data

[0319] Page 1

[0320] K=0.00000E+00,A3=1.23207E-04,A4=-2.64346E-07,A5=-6.70631E-08

[0321] A6=1.82466E-09, A7=-1.59622E-11, A8=-6.20200E-14, A9=2.06858E-15

[0322] A10 = -1.04117E-17

[0323] Page 2

[0324] K=-8.53791E-01,A3=1.65320E-04,A4=-4.01450E-06,A5=4.12521E-09

[0325] A6=9.64433E-11, A7=-1.78094E-12, A8=3.16260E-14, A9=6.61916E-16

[0326] A10 = -8.92584E-18

[0327] Page 9

[0328] K=0.00000E+00,A3=0.00000E+00,A4=-2.10717E-05,A5=0.00000E+00

[0329] A6=-6.55977E-08, A7=0.00000E+00, A8=-1.66719E-11, A9=0.00000E+00

[0330] A10 = -2.25629E-12

[0331] Page 10

[0332] K=0.00000E+00,A3=0.00000E+00,A4=4.94270E-06,A5=0.00000E+00

[0333] A6=4.28518E-09, A7=0.00000E+00, A8=1.37239E-11, A9=0.00000E+00

[0334] A10 = 0.00000E + 00

[0335] [Table 11]

[0336] Various data

[0337] Zoom ratio 1.07176

[0338] Wide-angle center telephoto

[0339] Focal length -7.2505 -7.4890 -7.7708

[0340] F-value -1.89769 -1.89966 -1.90218

[0341] Field of view: -66.7723 -66.1145 -65.3417

[0342] Like the height 17.2650 17.2650 17.2650

[0343] The lens's overall length is 531.0044 mm, 531.0164 mm, and 531.0251 mm.

[0344] BF 1.00464 1.01668 1.02526

[0345] d30 80.1300 77.1041 73.7905

[0346] d34 2.4064 2.3383 2.0000

[0347] d36 2.0000 5.0939 8.7459

[0348] d45 2.9859 2.9042 2.7968

[0349] d47 4.2696 4.3513 4.4587

[0350] Entrance pupil positions: 39.5645, 39.5759, 39.5918

[0351] Exit pupil position: -634.2339 -625.3536 -614.0913

[0352] The positions of the principal points on the front side are 32.2313, 31.9973, and 31.7228.

[0353] The positions of the rear principal points are 538.2074, 538.4547, and 538.7412.

[0354] [Table 12]

[0355]

[0356]

[0357] (Numerical Example 5)

[0358] Regarding the zoom lens system of numerical embodiment 5 (corresponding to embodiment 5), the surface data is shown in Table 13, various data are shown in Table 14, and single lens data are shown in Table 15 (unit is mm).

[0359] [Table 13]

[0360]

[0361]

[0362] Aspherical data, first surface

[0363] K=0.00000E+00,A3=1.17463E-04,A4=-2.31628E-07,A5=-6.59395E-08

[0364] A6=1.81310E-09, A7=-1.60936E-11, A8=-6.10381E-14, A9=2.09440E-15

[0365] A10 = -1.06332E-17

[0366] Page 2

[0367] K=-8.25922E-01,A3=1.59536E-04,A4=-4.03112E-06,A5=5.08423E-09

[0368] A6=1.00553E-10, A7=-1.90015E-12, A8=2.91500E-14, A9=6.51056E-16

[0369] A10 = -8.49456E-18

[0370] Page 9

[0371] K=0.00000E+00,A3=0.00000E+00,A4=-2.18898E-05,A5=0.00000E+00

[0372] A6=-7.41292E-08, A7=0.00000E+00, A8=4.43382E-11, A9=0.00000E+00

[0373] A10 = -2.46623E-12

[0374] Page 10

[0375] K=0.00000E+00,A3=0.00000E+00,A4=3.98821E-06,A5=0.00000E+00

[0376] A6=2.26149E-09, A7=0.00000E+00, A8=2.47661E-13, A9=0.00000E+00

[0377] A10 = 0.00000E + 00

[0378] [Table 14]

[0379]

[0380]

[0381] [Table 15]

[0382]

[0383]

[0384] (Numerical Example 6)

[0385] Regarding the zoom lens system of numerical embodiment 6 (corresponding to embodiment 6), the surface data is shown in Table 16, the various data are shown in Table 17, and the single lens data are shown in Table 18 (the unit is mm).

[0386] [Table 16]

[0387]

[0388]

[0389]

[0390] Aspherical data

[0391] Page 1

[0392] K=0.00000E+00,A3=1.21277E-04,A4=-5.82244E-07,A5=-5.95006E-08

[0393] A6=1.77842E-09, A7=-1.63746E-11, A8=-5.85060E-14, A9=2.11902E-15

[0394] A10 = -1.08872E-17

[0395] Page 2

[0396] K=-8.11394E-01,A3=1.65003E-04,A4=-4.20440E-06,A5=3.97809E-09

[0397] A6=1.14779E-10, A7=-1.71713E-12, A8=2.91519E-14, A9=6.24786E-16

[0398] A10 = -8.50847E-18

[0399] Page 9

[0400] K=0.00000E+00,A3=0.00000E+00,A4=-1.13910E-05,A5=0.00000E+00

[0401] A6=-2.46711E-08, A7=0.00000E+00, A8=-1.20244E-11, A9=0.00000E+00

[0402] A10 = -1.67140E-12

[0403] Page 10

[0404] K=0.00000E+00,A3=0.00000E+00,A4=5.61069E-06,A5=0.00000E+00

[0405] A6=9.40124E-09, A7=0.00000E+00, A8=3.22652E-11, A9=0.00000E+00

[0406] A10 = 0.00000E + 00

[0407] [Table 17]

[0408]

[0409] [Table 18]

[0410]

[0411]

[0412] Table 19 below shows the corresponding values ​​of each conditional expression in each numerical embodiment.

[0413] [Table 19]

[0414]

[0415]

[0416] Table 20 below shows the values ​​of the variables in each conditional expression (1) to (13) in each numerical embodiment and the focal length of each group.

[0417] [Table 20]

[0418]

[0419]

[0420] fp: Focal length of the magnifying optical system

[0421] fr: The focal length of the relay optical system at the wide-angle end.

[0422] fw: The focal length of the entire system at the wide-angle end.

[0423] fr1: Focal length of the first lens group

[0424] frn: Focal length of the negative lens group

[0425] Ts: The longest air gap in the magnifying optical system.

[0426] Tpr: The distance from the outermost magnified side of the rear group of the magnifying optical system to the center image.

[0427] Tp: The distance from the surface closest to the magnification side of the magnifying optical system to the center of the image.

[0428] Tr: The distance from the center image at the wide-angle end to the closest reduction side surface of the relay optics.

[0429] fpr: Focal length of the rear element of the magnifying optical system

[0430] fpf: Focal length of the front group of the magnifying optical system

[0431] ωm: The maximum half-field angle at the wide-angle end.

[0432] ym: The height at which the outermost principal ray at the telescope passes through the lens surface.

[0433] L1R1: The central radius of curvature of the lens's magnifying side closest to the magnifying side.

[0434] L1R2: The lens closest to the magnifying side reduces the central radius of curvature of the side surface.

[0435] fr2: Focal length of the second lens group

[0436] fr3: Focal length of the third lens group.

[0437] fr4: Focal length of the 4th lens group

[0438] fr5: Focal length of the 5th lens group.

[0439] fr6: Focal length of the 6th lens group.

[0440] fr7: Focal length of the 7th lens group.

[0441] fr8: Focal length of the 8th lens group.

[0442] Tables 21 and 22 below show the values ​​of |ym / (fw·tan(ωm))| for conditional expression (10) and Tg for conditional expression (11) in each numerical embodiment. Additionally, the lens material Z330R is a product name of cyclic olefin polymer (COP) (Zeon Corporation). Lens element L1 can be manufactured using various synthetic resins, thereby achieving lightweight construction. The remaining lens elements L2 to L25 are also manufactured using various synthetic resins, thus achieving lightweight construction as well.

[0443] [Table 21]

[0444]

[0445] [Table 22]

[0446]

[0447] (Implementation Method 2)

[0448] The following uses Figure 19 The following describes Embodiment 2 of this disclosure. Figure 19 This is a block diagram illustrating an example of the image projection apparatus according to this disclosure. The image projection apparatus 100 includes: an 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 includes liquid crystal, DMD, etc., and generates an image projected onto the screen SR via the optical system 1. The light source 102 includes LED (light-emitting diode), laser, etc., and provides light to the image forming element 101. The control unit 110 includes CPU or MPU, etc., and controls the apparatus as a whole and its components. The optical system 1 may also be configured as an interchangeable lens that can be freely mounted and detached from the image projection apparatus 100. In this case, the device for removing the optical system 1 from the image projection apparatus 100 is an example of the main apparatus.

[0449] The image projection device 100 described above, through the optical system 1 according to Embodiment 1, can reduce the torque acting on the center of gravity of the optical system 1, reduce the impact of heat, and achieve wide-angle zoom function.

[0450] (Implementation Method 3)

[0451] The following uses Figure 20 The following describes embodiment 3 of this disclosure. Figure 20 This is a block diagram illustrating an example of the imaging device disclosed herein. The imaging device 200 includes: an optical system 1 as disclosed in Embodiment 1, an imaging element 201, a control unit 210, etc. The imaging element 201 includes a CCD (charge-coupled device) image sensor, a CMOS image sensor, etc., which receives light from the optical image of the object OBJ formed by the optical system 1 and converts it into an electrical image signal. The control unit 110 includes a CPU or MPU, etc., which controls the entire device and its components. The optical system 1 may also be configured as an interchangeable lens that can be freely mounted and detached from the imaging device 200. In this case, the device for removing the optical system 1 from the imaging device 200 is an example of the main device.

[0452] The above-described camera device 200, through the optical system 1 described in Embodiment 1, can reduce the torque acting on the center of gravity of the optical system 1, mitigate the effects of heat, and achieve wide-angle zoom function.

[0453] As described above, embodiments have been explained as part of the technical disclosure herein. Drawings and detailed descriptions are provided for this purpose.

[0454] Therefore, the structural elements described in the accompanying drawings and detailed description include not only those essential for solving the problem, but also structural elements that are not essential for solving the problem, in order to illustrate the above-described technology. Thus, these non-essential structural elements are described in the accompanying drawings or detailed description, but should not be directly assumed to be essential.

[0455] Furthermore, the above-described embodiments are used to illustrate the technology in this disclosure, and therefore various changes, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents.

[0456] Industrial availability

[0457] This disclosure can be applied to image projection devices such as projectors and head-up displays, as well as video recording devices such as digital cameras, digital camcorders, surveillance cameras in surveillance systems, web cameras, and vehicle-mounted cameras. In particular, this disclosure can be applied to optical systems that require high image quality, such as projectors, digital camera systems, and digital camcorder systems.

Claims

1. An optical system comprising a plurality of lens elements, each having an intermediate imaging position conjugate to a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, the optical system comprising: A magnifying optical system, comprising a lens element among the plurality of lens elements located further toward the magnification side than the intermediate imaging position; and The relay optical system includes a lens element among the plurality of lens elements located further toward the reduction side than the intermediate imaging position. The relay optical system has a first lens group on the side closest to the magnification. The relay optical system has two lens groups on the narrower side than the first lens group. The relay optical system has a negative lens group positioned between the two lens groups. During zooming, the two lens groups move while the negative lens group is fixed.

2. The optical system according to claim 1, wherein, The first lens group has positive optical power. The first lens group and the magnifying optical system are fixed during zooming.

3. The optical system according to claim 1, wherein, The relay optical system also has other negative lens groups. The negative optical power of the negative lens group is smaller than that of the other negative lens groups.

4. The optical system according to claim 1, wherein, The negative lens group has an aperture.

5. The optical system according to claim 1, wherein, The lens closest to the narrowing side of the magnifying optical system is a negative lens.

6. The optical system according to claim 1, wherein, The lens on the magnifying side of the relay optical system is a positive lens.

7. The optical system according to claim 1, wherein, The optical system satisfies the following condition (1). 0.1<fp / fr<0.5・・・(1) here, fp: The focal length of the magnifying optical system fr: The focal length of the relay optics system at the wide-angle end.

8. The optical system according to claim 1, wherein, The optical system satisfies the following condition (2). 100<fr1 / fw<1000・・・(2) here, fr1: The focal length of the first lens group. fw: The focal length of the entire system at the wide-angle end.

9. The optical system according to claim 1, wherein, The optical system satisfies the following condition (3). 5<frn / fw<50・・・(3) here, frn: The focal length of the negative lens group. fw: The focal length of the entire system at the wide-angle end.

10. The optical system according to claim 1, wherein, The magnifying optical system has the longest air gap, and has a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side, with the longest air gap as the boundary. The optical system satisfies the following conditions (4) and (5). 6.5<|Ts / fw|<12.0・・・(4) 3.0<|Tpr / fw|<8.0・・・(5) here, Ts: The longest air gap of the magnifying optical system. fw: The focal length of the entire system at the wide-angle end. Tpr: The distance from the surface of the rear group of the magnifying optical system closest to the magnified side to the middle image.

11. The optical system according to claim 1, wherein, The optical system satisfies the following condition (6). 0.8 < Tp / Tr < 1.0 … (6) here, Tp: The distance from the surface of the magnifying optical system closest to the magnifying side to the intermediate imaging position. Tr: The distance from the intermediate imaging position at the wide-angle end to the surface of the relay optics closest to the narrowed side.

12. The optical system according to claim 1, wherein, The magnifying optical system has the longest air gap, and with the longest air gap as the boundary, there is a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side. The optical system satisfies the following condition (7). 7<|fpr / fw|<12…(7) here, fpr: The focal length of the rear element of the magnifying optical system. fw: The focal length of the entire system at the wide-angle end.

13. The optical system according to claim 1, wherein, The magnifying optical system has the longest air gap, and with the longest air gap as the boundary, there is a front group of the magnifying optical system on the magnifying side and a rear group of the magnifying optical system on the reducing side. The optical system satisfies the following condition (8). 2<|fpf / fw|<5…(8) here, fpf: The focal length of the front group of the magnifying optical system. fw: The focal length of the entire system at the wide-angle end.

14. The optical system according to claim 1, wherein, A first lens element is disposed on the magnifying side of the magnifying optical system. The first lens element has a first lens magnifying side facing the magnifying side and a first lens reducing side facing the reducing side. The magnifying side and the reducing side of the first lens satisfy the following condition (9) within the range from r > 0 to the effective diameter. dZ(r) / dr>0 …(9) here, r: the distance from the vertex along a plane perpendicular to the optical axis of the optical system, where r > 0. Z(r): The sag of the face, where Z=0 is set at the vertex (r=0), and the sign is + for shrinking lateral displacement relative to the vertex and - for expanding lateral displacement.

15. The optical system according to claim 1, wherein, A first lens element, which is made of synthetic resin, is disposed on the side closest to the magnification of the magnifying optical system.

16. The optical system according to claim 1, wherein, All lens elements that satisfy condition (10) among the plurality of lens elements also satisfy condition (11), and one lens element among the plurality of lens elements does not satisfy either condition (10) or condition (11). |ym / (fw·tan(ωm))|<3.0…(10) Tg>300℃ …(11) here, ωm: The maximum half-field angle at the wide-angle end. ym: The height at which the outermost principal ray at the telescope passes through the lens surface. Tg: Glass transition point of the lens material fw: The focal length of the entire system at the wide-angle end.

17. The optical system according to claim 1, wherein, The optical system satisfies the following condition (12). ωm>65° …(12) here, ωm: The maximum half-field angle at the wide-angle end.

18. The optical system according to claim 1, wherein, The optical system satisfies the following condition (13). -1.5<(L1R1+L1R2) / (L1R2-L1R1)<-0.9…(13) here, L1R1: The central radius of curvature of the lens's magnifying side closest to the magnifying side. L1R2: The central radius of curvature of the lens on the magnifying side is reduced.

19. An image projection device, comprising: The optical system according to any one of claims 1 to 18; and An image forming element generates an image that is projected onto a screen via the optical system.

20. A camera device, comprising: The optical system according to any one of claims 1 to 18; and The camera element receives light from the optical image formed by the optical system and converts it into an electrical image signal.

Images