JP2017037165A - Optical system and image projection device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system in which good optical performance can be easily obtained over the whole projection distance, and an image projection device using the optical system.SOLUTION: The optical system is composed of, successively from an enlargement conjugate side to a reduction conjugate side, a first lens group having a negative refractive power and a rear group comprising at least one lens group. The first lens group is composed of, from the enlargement conjugate side to the reduction conjugate side, a subgroup B1a having a negative refractive power, a subgroup B1b having a negative refractive power, a subgroup B1c having a negative refractive power, and a subgroup B1d having a positive refractive power. Upon focusing from an infinite distance to a close distance, the subgroup B1a is immobile and the subgroup B1b, the subgroup B1c and the subgroup B1d move to the reduction conjugate side while enlarging an interval between the subgroup B1b and the subgroup B1c and reducing an interval between the subgroup B1c and the subgroup B1d.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical system, and is suitable, for example, as a projection optical system used in an image projection apparatus (projector) that magnifies and projects an image displayed on an image display element, an imaging optical system used in a digital camera, or the like.

  The projection optical system used in the image projection apparatus that projects the image displayed on the image display element onto a large screen can project the entire image formed on the image display element from various projection distances with high resolution on the screen surface. It is requested. Further, there is a demand for a wide angle of view so that it can be projected over a screen wider than a short distance.

  2. Description of the Related Art Conventionally, a projection optical system for an image projection apparatus that satisfies these demands is composed of a first lens group having a negative refractive power and a rear group including one or more lens groups in order from the magnification conjugate side to the reduction conjugate side. A retrofocus type projection optical system is known. Also known is a projection optical system that reduces aberration fluctuations during focusing by moving a plurality of lens groups in response to a change in distance when the screen changes from infinity on the magnification conjugate side to a close distance. (Patent Document 1).

  Patent Document 1 discloses a zoom lens including a first lens unit having a negative refractive power that is fixed during zooming and a plurality of lens units that move during zooming in order from the magnification conjugate side to the reduction conjugate side. Then, the first lens unit is divided into four elements, ie, a negative refractive power 1a group, a negative refractive power 1b group, a positive or negative refractive power 1f group, and a negative refractive power 1c group in order from the magnification side. It consists of a lens. A zoom lens is disclosed in which the first a group and the first f group are fixed during focusing from infinity to a short distance, the first b group is moved to the reduction conjugate side, and the first c group is moved to the enlargement conjugate side.

JP 2013-68690 A

  A projection optical system used in a projector is required to have a high-quality optical image with high image quality over the entire projection distance. In order to satisfy these demands in the above-mentioned projection optical system, it is important to select the lens configuration of the entire system, the selection of lens groups that move during focusing, and the appropriate setting of the refractive power of those lens groups. . If the selection of the lens group at this time, the refractive power of the selected lens group, the lens configuration, etc. are inappropriate, it will be difficult to obtain good optical performance over the entire projection distance.

  In Patent Document 1, the first lens group having a negative refractive power is composed of four lens groups. During focusing, the first a group and the first f group are fixed, and the first b group and the first c group are moved. However, since the refractive power sharing of each lens group is not always sufficient when the first f group is fixed during focusing, there is a tendency for aberration fluctuation to increase during focusing.

  An object of the present invention is to provide an optical system in which good optical performance can be easily obtained over the entire projection distance and an image projection apparatus using the same.

The optical system of the present invention is an optical system composed of a first lens group having a negative refractive power and a rear group including one or more lens groups in order from the magnification conjugate side to the reduction conjugate side.
The first lens unit includes, in order from the magnification conjugate side to the reduction conjugate side, a negative refractive power subgroup B1a, a negative refractive power subgroup B1b, a negative refractive power subgroup B1c, and a positive refractive power subgroup. B1d, the subgroup B1a does not move during focusing from infinity to the nearest, and the subgroup B1b, the subgroup B1c, and the subgroup B1d are all on the reduction conjugate side, and the subgroup B1b and the subgroup It is characterized by moving while decreasing the distance between the partial group B1c and the partial group B1d while increasing the distance between B1c.

  According to the present invention, it is possible to obtain an optical system that can easily obtain good optical performance over the entire projection distance.

(A), (B) Lens sectional view of the optical system of Example 1 of the present invention (A), (B) Lens cross-sectional view at the wide-angle end of Example 1 (A), (B) aberration diagrams of the optical system of Example 1 (A), (B) aberration diagrams of the optical system of Example 1 (A), (B) aberration diagrams of the optical system of Example 1 (A), (B) Chromatic aberration diagram of the optical system of Example 1 (A), (B) Chromatic aberration diagram of the optical system of Example 1 (A), (B) Chromatic aberration diagram of the optical system of Example 1 (A), (B) Lens sectional view of the optical system of Example 2 of the present invention (A), (B) Lens cross-sectional view at the wide-angle end of Example 2 (A), (B) aberration diagrams of the optical system of Example 2 (A), (B) aberration diagrams of the optical system of Example 2 (A), (B) aberration diagrams of the optical system of Example 2 (A), (B) Chromatic aberration diagrams of the optical system of Example 2 (A), (B) Chromatic aberration diagrams of the optical system of Example 2 (A), (B) Chromatic aberration diagrams of the optical system of Example 2 (A), (B) Lens sectional view of the optical system of Example 3 of the present invention (A), (B), (C) Aberration diagrams of the optical system of Example 3 (A), (B), (C) chromatic aberration of magnification of the optical system of Example 3 Schematic diagram of main parts of the image projection apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is a projection optical system suitable for an image projection apparatus (projector). The optical system according to the present invention includes, in order from the magnification conjugate side (object side) to the reduction conjugate side (image side), a first lens group having a negative refractive power and a rear group including one or more lens groups.

  The optical system of the present invention is a single focal length projection lens or a projection zoom lens. In the first lens unit, in order from the magnification conjugate side to the reduction conjugate side, the negative refractive power subgroup B1a, the negative refractive power subgroup B1b, the negative refractive power subgroup B1c, and the positive refractive power subgroup B1d. Consists of. At the time of focusing from infinity to close, the subgroup B1b, the subgroup B1c, and the subgroup B1d move to the reduction conjugate side while changing the interval between adjacent subgroups. The optical system of the present invention can also be applied as an imaging optical system for an imaging apparatus such as a digital camera.

  FIGS. 1A and 1B are lens cross-sectional views at the wide-angle end and the telephoto end of the optical system according to Embodiment 1 of the present invention at a projection distance of 1205 mm. Here, the projection distance is a distance from the first lens surface when numerical data described later is expressed in mm. This is all the same below. 2A and 2B are lens cross-sectional views at the projection distance 3443 mm and the projection distance 861 mm at the wide angle end according to the first embodiment. FIGS. 3A and 3B are aberration diagrams at the wide-angle end and the telephoto end when the projection distance of the optical system of Example 1 is 1205 mm. 4A and 4B are aberration diagrams at the projection distance 861 mm and the projection distance 3443 mm at the wide angle end of the optical system according to the first embodiment.

  FIGS. 5A and 5B are aberration diagrams at the projection distance 1076 mm and the projection distance 4304 mm at the telephoto end of the optical system according to the first embodiment. 6A and 6B are chromatic aberration diagrams of magnification at the wide-angle end and the telephoto end at the projection distance of 1205 mm of the optical system of Example 1. FIG. FIGS. 7A and 7B are chromatic aberration diagrams of magnification at the projection distance 861 mm and the projection distance 3443 mm at the wide angle end of the optical system according to the first embodiment. FIGS. 8A and 8B are chromatic aberration diagrams of magnification at the projection distance of 1076 mm and the projection distance of 4304 mm at the telephoto end of the optical system of the first embodiment.

  FIGS. 9A and 9B are lens cross-sectional views at the wide-angle end and the telephoto end at a projection distance of 1205 mm of the optical system according to Example 2 of the present invention. 10A and 10B are lens cross-sectional views at the projection distance 3443 mm and the projection distance 861 mm at the wide angle end according to the second embodiment. FIGS. 11A and 11B are aberration diagrams at the wide-angle end and the telephoto end when the projection distance of the optical system according to the second embodiment is 1205 mm. FIGS. 12A and 12B are aberration diagrams at the projection distance 861 mm and the projection distance 3443 mm at the wide angle end of the optical system according to the second embodiment. FIGS. 13A and 13B are aberration diagrams at the projection distance 1076 mm and the projection distance 4304 mm at the telephoto end of the optical system according to the second embodiment.

  FIGS. 14A and 14B are chromatic aberration diagrams of magnification at the wide-angle end and the telephoto end at the projection distance 1205 mm of the optical system of the second embodiment. 15A and 15B are chromatic aberration diagrams of magnification at a projection distance 861 mm and a projection distance 3443 mm at the wide-angle end of the optical system according to the second embodiment. FIGS. 16A and 16B are chromatic aberration diagrams of magnification at a projection distance of 1076 mm and a projection distance of 4304 mm at the telephoto end of the optical system according to the second embodiment.

  FIGS. 17A and 17B are lens cross-sectional views at the projection distance 3443 mm and the projection distance 861 mm of the optical system according to Example 3 of the present invention. 18A, 18B, and 18C are aberration diagrams of the optical system of Example 3 at a projection distance of 1205 mm, a projection distance of 861 mm, and a projection distance of 3443 mm. FIGS. 19A, 19B, and 19C are chromatic aberration diagrams of magnification at the projection distance 1205 mm, the projection distance 861 mm, and the projection distance 3443 mm of the optical system of Example 3. FIG. FIG. 20 is a schematic diagram of a main part of an image projection apparatus (projector) having the optical system of the present invention.

  The optical system of each embodiment is a projection lens (projection optical system) used in an image projection apparatus (projector). In the lens cross-sectional view, the left side is the screen (enlarged conjugate side), (object side), and the right side is the projected image side (image display element side), (reduced conjugate side), and (image side). In the lens cross-sectional view, LA is an optical system.

  The optical systems of the first and second embodiments are configured by a zoom lens, and the optical system of the third embodiment is a single focal length projection lens. i indicates the order of the lens groups from the magnification conjugate side, and Bi is the i-th lens group. LR is a rear group composed of one or more lens groups. B1a, B1b, B1c, and B1d are partial groups constituting the first lens group B1. ST is an aperture stop. IP corresponds to an original image (projected image) such as a liquid crystal panel (image display element).

  In this embodiment, an image display element for forming an original image is arranged. S is the screen surface. PR is an optical block corresponding to a prism for color separation and color synthesis, an optical filter, a face plate (parallel plate glass), a quartz low-pass filter, an infrared cut filter, and the like.

  1 and 9, arrows indicate the moving direction (movement locus) of the lens group during zooming from the wide-angle end to the telephoto end. 2 and 10, the arrows indicate the moving direction of the subgroup during focusing from infinity to close at the wide angle end. In FIG. 17, the arrow indicates the moving direction of the subgroup during focusing from infinity to close.

  An optical system including the zoom lenses of Examples 1 and 2 will be described. In the zoom lenses of Examples 1 and 2, the first lens unit does not move during zooming, and the interval between adjacent lens units changes. In the zoom lenses of Embodiments 1 and 2, the wide-angle end and the telephoto end are zoom positions when the zooming lens groups are positioned at both ends of the range in which the mechanism can move on the optical axis. The zoom lenses of Embodiments 1 and 2 include, in order from the magnification conjugate side to the reduction conjugate side, a first lens unit B1 (lens L11 to L17) having a negative refractive power and a rear unit LR (lenses L18 to L26). .

  The rear group LR includes a second lens unit B2 (lens L18) having a positive refractive power and a third lens unit B3 (lens L19, lens L20) having a positive refractive power. Further, it includes a fourth lens unit B4 (lens L21 to L25) having a negative refractive power and a fifth lens unit B5 (lens L26) having a positive refractive power. During zooming, the first lens unit B1 and the fifth lens unit B5 do not move. During zooming from the wide-angle end to the telephoto end, the second lens unit B2, the third lens unit B3, and the fourth lens unit B4 move toward the magnification conjugate side along different paths.

  The first lens unit B1 includes, in order from the magnification conjugate side to the reduction conjugate side, a negative refractive power subgroup B1a (lens L11) and a negative refractive power subgroup B1b (lenses L12 to L14). Further, it is composed of a sub-group B1c (lens L15) having a negative refractive power and a sub-group B1d (lens L16, L17) having a positive refractive power. At the time of focusing from infinity to the close (as the projection distance is changed from the far distance), the subgroup B1b, the subgroup B1c, and the subgroup B1d move while changing the interval between the subgroups adjacent to the reduction conjugate side.

  The first lens unit B1 includes, in order from the magnification conjugate side to the reduction conjugate side, a negative lens, a positive lens, a negative lens, a negative lens, a negative lens, a negative lens, and seven positive lenses L11 to L17. The second lens group B2 is composed of a single positive lens L18. The third lens unit B3 includes two lenses L19 to L20, which are a positive lens and a negative lens, in order from the magnification conjugate side to the reduction conjugate side. The fourth lens unit B4 includes five lenses L21 to L25 in order from the magnification conjugate side to the reduction conjugate side, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens. The fifth lens unit B5 includes one positive lens L26.

  The optical system of Example 3 includes a first lens unit B1 (lenses L11 to L17) and a rear unit LR (lens L18 to L26) having negative refractive power in order from the magnification conjugate side to the reduction conjugate side. The rear group LR includes a lens group having a positive refractive power. The first lens unit B1 includes, in order from the magnification conjugate side to the reduction conjugate side, a negative refractive power subgroup B1a, a negative refractive power subgroup B1b, a negative refractive power subgroup B1c, and a positive refractive power subgroup. B1d. At the time of focusing from infinity to the close (as the projection distance is changed from the far distance), the subgroup B1b, the subgroup B1c, and the subgroup B1d move while changing the interval between the subgroups adjacent to the reduction conjugate side.

  Specifically, during focusing from infinity to the closest distance, the distance between the subgroup B1b and the subgroup B1c is increased, and the distance between the subgroup B1c and the subgroup B1d is decreased while moving toward the reduction conjugate side. The lens configuration of the first lens unit B1 is the same as that of the first embodiment. The second lens group B2 includes, in order from the magnification conjugate side to the reduction conjugate side, a positive lens, a positive lens, a negative lens, a negative lens, a positive lens, a negative lens, a positive lens, a positive lens, and positive lenses L18 to L26.

  In the spherical aberration diagram, the solid line indicates the wavelength of 550 nm. In the astigmatism diagram, the dotted line indicates the meridional image plane, and the solid line indicates the sagittal image plane. Fno is an F number, and ω is a half angle of view (degrees). In the aberration diagrams, spherical aberration is drawn at a scale of 0.1 mm, astigmatism is drawn at a scale of 0.1 mm, and distortion is drawn at a scale of 0.5%. In the lateral chromatic aberration diagram, each color (wavelength 620 nm, wavelength 470 nm) with respect to the reference wavelength (550 nm) is shown.

  Next, a more preferable configuration than the optical system of the present invention will be described. In each embodiment, the projected image is projected onto the screen. However, in order to simplify the explanation, the light flux from the screen (object) on the enlargement conjugate side is projected on the reduction conjugate side (image) as the order of passage of the light flux. In the following description, it is assumed that an image is formed by being incident on the surface. In each embodiment, the subgroup B1a does not move during focusing from infinity to the closest position, and the subgroup B1b, the subgroup B1c, and the subgroup B1d all move toward the reduction conjugate side. Specifically, the distance between the partial group B1b and the partial group B1c is increased while the distance between the partial group B1c and the partial group B1d is decreased.

  The subgroup B1a in which the incident height of the off-axis light beam is increased at the time of focusing is fixed, and aberration fluctuations at the time of focusing are suppressed. Further, by making the entire lens length unchanged, the mechanical mechanism is simplified by suppressing the change in the center of gravity of the lens during focusing. In addition, the overall length of the lens is unchanged, and the appearance quality is improved.

  The subgroup B1b mainly has a function of correcting fluctuations in off-axis aberrations such as field curvature that occur during focusing. The subgroup B1b has a strong negative refractive power, and is configured to be able to satisfactorily correct off-axis aberration fluctuations such as curvature of field with a small moving distance. In addition, the subgroup B1b has a function of correcting the variation of distortion aberration during focusing. Since the subgroup B1b has a strong negative refractive power, the partial group B1b is constituted by a plurality of lenses to share the negative refractive power.

  In each embodiment, by adopting the above-described configuration, aberration variation during focusing is reduced, and an optical system having high optical performance over the entire object distance range is obtained. In each embodiment, it is preferable to satisfy one or more of the following conditional expressions. The focal length of the subgroup B1b is fB1b, and the focal length of the first lens group B1 when focusing on infinity is fB1. Let fB1cd be the focal length of the combined system of the subgroup B1c and the subgroup B1d when focusing on infinity. The focal length of the subgroup B1c is fB1c, and the focal length of the subgroup B1d is fB1d. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.2 <fB1b / fB1 <0.9 (1)
−8.0 <fB1cd / fB1b <−1.0 (2)
-6.0 <fB1c / fB1d <0.0 (3)
In addition, when the optical system of each embodiment and an image display element that forms an original image are used in an image projection apparatus that projects the original image formed by the image display element by the optical system, the following conditional expression is satisfied: Is preferred.

The maximum projection half field angle of the optical system (the projection half field angle at the wide-angle end when the optical system is a zoom lens, and the projection half field angle of this single focus optical system in the case of a single focus optical system) is ω ( Degree). At this time,
39.0 ° <ω <55.0 ° (4)
It is good to satisfy the following conditional expression.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) is for reducing aberration fluctuations during focusing and obtaining good optical performance. Conditional expression (1) relates to the ratio of the focal length of the subgroup B1b to the focal length of the first lens group B1. When the negative refractive power of the subgroup B1b is increased beyond the lower limit value of the conditional expression (1) (when the absolute value of the negative refractive power is increased), the under-field curvature and the distortion are increased as compared with the subgroup B1b. Optical performance decreases.

  If the upper limit of conditional expression (1) is exceeded and the negative refractive power of the subgroup B1b becomes weaker (when the absolute value of the negative refractive power becomes smaller), field curvature and distortion increase during focusing, and the total object distance It becomes difficult to obtain high optical performance over a wide range. In each embodiment, the configuration is such that the incident height h of the off-axis principal ray from the optical axis is small, so that fluctuations in off-axis aberrations are reduced during focusing. This is to reduce aberration variation during focusing and obtain good optical performance.

  If the lower limit of conditional expression (2) is exceeded and the focal length of the synthesis system becomes too long, lateral chromatic aberration will increase during focusing. If the upper limit of conditional expression (2) is exceeded and the focal length of the combining system becomes too short, the variation in field curvature during focusing will increase and the optical performance will deteriorate. The subgroup B1d has a lens configuration having one cemented lens, and mainly corrects lateral chromatic aberration.

  Further, the negative lens included in the subgroup B1c corrects the chromatic aberration of magnification of the entire lens by generating the chromatic aberration of magnification under the g-line. At the same time, the off-axis principal ray is bent in the direction away from the optical axis to increase the incident height h of the off-axis ray incident on the positive lens of the subgroup B1d arranged on the reduction conjugate side. The effect of correcting chromatic aberration of magnification by the lens is enhanced.

  Conditional expression (3) relates to the ratio of the focal lengths of the subgroup B1d and the subgroup B1c. If the negative refractive power of the subgroup B1c becomes too weak beyond the lower limit of conditional expression (3), the correction of lateral chromatic aberration will be insufficient. Since the subgroup B1c has negative refractive power, the upper limit value of the conditional expression (3) is not exceeded. However, the negative refracting power of the subgroup B1c becomes strong. When the upper limit of conditional expression (3) is approached, the lateral chromatic aberration is overcorrected, which is not good. In addition, the subgroup B1b has a positive lens on the most magnification conjugate side, and mainly corrects distortion aberrations favorably.

  Conditional expression (4) is a projection when the optical system of the present invention and an image display element that forms an original image are used in an image projection apparatus that projects the original image formed by the image display element by the optical system. Let the half angle of view be ω (degrees). Here, when the optical system is a zoom lens, the projection half angle of view is at the wide-angle end. When the lower limit of conditional expression (4) is exceeded, lateral chromatic aberration is overcorrected. If the upper limit is exceeded, lateral chromatic aberration will be undercorrected and distortion will increase. More preferably, the numerical ranges of the conditional expressions (1) to (4) are set as follows.

0.3 <fB1b / fB1 <0.9 (1a)
−7.0 <fB1cd / fB1b <−2.0 (2a)
−5.0 <fB1c / fB1d <−0.5 (3a)
40.0 ° <ω <50.0 ° (4a)

  Next, the characteristics of the lens configurations other than those described above for each lens group and each partial group are as follows. The subgroup B1b has one or more positive lenses. The subgroup B1d has one or more cemented lenses. The subgroup B1a has an aspheric lens surface. The subgroup B1c is composed of one negative lens. The subgroup B1c only needs to have at least one negative lens. The first lens unit B1 includes a negative lens, a positive lens, a negative lens, a negative lens, a negative lens, a negative lens, and a positive lens in order from the magnification conjugate side to the reduction conjugate side.

  The image projection apparatus of the present invention has an optical system and an image display element for forming an original image, and projects the original image formed by the image display element by the optical system.

  Next, the image projection apparatus of the present invention will be described with reference to FIG. In FIG. 20, reference numeral 41 denotes a light source. Reference numeral 42 denotes an illumination optical system that realizes illumination with less unevenness on the image display element and has a function of aligning the polarization direction of emitted light to an arbitrary direction of P-polarized light or S-polarized light. A color separation optical system 43 separates light from the illumination optical system 42 into an arbitrary color corresponding to the image display element.

  Reference numerals 47, 48, and 49 denote image display elements made of reflective liquid crystal that modulates incident polarized light according to an electric signal. Reference numerals 44 and 45 denote polarization beam splitters that transmit or reflect light according to modulation by the image display elements 47, 48, and 49, respectively. A color combining optical system 46 combines the light from the image display elements 47, 48 and 49 into one. Reference numeral 50 denotes a projection optical system that projects light synthesized by the color synthesis optical system 46 onto a projection object such as a screen 51. 50 uses the optical system of the present invention. Thereby, changes in various aberrations are favorably corrected during focusing, and an image projection apparatus having good optical performance over the entire screen is obtained.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  Next, numerical data of the optical system of each example is shown. The surface number in the lens configuration of the numerical data is a number assigned to each lens surface in order from the enlargement conjugate side to the reduction conjugate side. r represents the radius of curvature of each lens surface, and d represents the distance (physical distance) on the optical axis between the lens surface i and the lens surface (i + 1). The three surfaces on the image side correspond to glass blocks.

  The interval described as variable in the table changes with focusing or zooming. Further, nd and νd indicate the refractive index and the Abbe number for the d-line of the material constituting each lens, respectively. Table A shows the focal length, aperture ratio (F number), projection half angle of view, and total lens length (distance from the first lens surface to the projection surface) of the optical system of numerical data. BF is a back focus, and is an air conversion length from the final lens surface to the image surface (projected surface). This indicates the distance between the lens groups during zoom ratio, focusing, or zooming. In addition, aspherical coefficients A to F for showing the aspherical shape are shown.

y represents the coordinate in the radial direction of the lens surface, and x represents the coordinate in the optical axis direction. Furthermore, E-X indicates a ^{10 -X.} At this time, the aspherical shape is as follows.

x = (y ² / R) / [1+ {1− (1 + K) (y ² / R ² )} ^1/2 ] + Ay ⁴ + By ⁶ + Cy ⁸ + Dy ¹⁰ + Ey ¹² + Fy ¹⁴
Table 1 shows the relationship between the above-described embodiments and numerical values.

<Example 1>

Lens configuration
Wide angle telephoto
f (focal length) 12.61 15.77
F (aperture ratio) 2.80 2.88
Projection half angle of view (degrees) 45.9 39.6
Total lens length 187.0
BF 59.2
Zoom ratio 1.25

* r 1 = 278.72 d 1 = 4.50 n 1 = 1.716 ν 1 = 53.9
r 2 = 40.10 d 2 = variable
r 3 = 160.28 d 3 = 3.16 n 2 = 1.489 ν 2 = 70.2
r 4 = 586.33 d 4 = 2
* r 5 = 500.00 d 5 = 2.50 n 3 = 1.859 ν 3 = 40.4
* r 6 = 43.11 d 6 = 24.93
r 7 = -37.99 d 7 = 2.20 n 4 = 1.498 ν 4 = 81.5
r 8 = 52.99 d 8 = variable
r 9 = -188.83 d 9 = 2.20 n 5 = 1.888 ν 5 = 40.8
r10 = 1043.90 d10 = variable
r11 = 159.99 d11 = 2.30 n 6 = 1.932 ν 6 = 20.9
r12 = 69.29 d12 = 9.61 n 7 = 1.910 ν 7 = 31.3
r13 = -58.80 d13 = variable
r14 = 61.21 d14 = 4.15 n 8 = 1.766 ν 8 = 40.1
r15 = -3796.24 d15 = variable
r16 = 238.21 d16 = 4.03 n 9 = 1.518 ν 9 = 64.1
r17 = -20.27 d17 = 1.00 n10 = 1.888 ν10 = 40.8
r18 = -36.47 d18 = variable
STr19 = ∞ d19 = variable
r20 = 1095.01 d20 = 1.50 n11 = 1.856 ν11 = 32.3
r21 = 19.93 d21 = 6.04 n12 = 1.518 ν12 = 64.1
r22 = -17.41 d22 = 1.47
r23 = -15.98 d23 = 2.00 n13 = 1.910 ν13 = 31.3
r24 = 60.05 d24 = 3.97 n14 = 1.489 ν14 = 70.2
r25 = -44.11 d25 = 5.33
r26 = -1146.99 d26 = 8.69 n15 = 1.498 ν15 = 81.5
r27 = -23.17 d27 = variable
r28 = 95.23 d28 = 4.51 n16 = 1.902 ν16 = 20.4
r29 = -164.20 d29 = 2.00
r30 = ∞ d30 = 22.40 n17 = 1.516 ν18 = 64.1
r31 = ∞ d31 = 17.7 n18 = 1.805 ν19 = 25.4
r32 = ∞ d32 = 7.2

When zoomed (1205mm) When focused (wide-angle end)
Group spacing Wide angle Telephoto Group spacing 861mm 1205mm 3443mm
d13 27.64 5.88 d 2 13.90 13.79 13.60
d15 31.91 40.48 d 8 8.13 7.29 5.90
d18 1.50 2.72 d10 2.50 3.04 3.95
d19 4.25 1.20 d13 27.23 27.64 28.32
d27 1.50 16.51


Aspheric coefficient
r1 K = 0 A = 6.78E-06 B = -6.28E-09 C = 7.45E-12 D = -6.12E-15
E = 3.20E-18 F = -8.86E-22 G = 1.16E-25
r5 K = 0 A = -1.15E-05 B = 3.87E-08 C = -4.63E-11 D = 8.87E-15
E = -3.85E-18 F = 5.02E-20 G = -3.88E-23
r6 K = 0 A = -2.82E-06 B = 2.58E-08 C = 1.91E-11 D = -9.44E-14
E = 4.50E-17 F = -1.30E-19 G = 3.55E-22

<Example 2>

Lens configuration
Wide angle telephoto
f (Focal distance) 12.61 15.77
F (Aperture ratio) 2.80 2.88
Projection half angle of view (degrees) 45.8 39.5
Total lens length 189.8
BF 59.2
Zoom ratio 1.25

r 1 = 323.22 d 1 = 3.73 n 1 = 1.716 ν 1 = 53.9
r 2 = 45.50 d 2 = variable
r 3 = 410.25 d 3 = 3.17 n 2 = 1.489 ν 2 = 70.2
r 4 = -472.36 d 4 = 2
* r 5 = 500.00 d 5 = 2.77 n 3 = 1.859 ν 3 = 40.4
* r 6 = 35.68 d 6 = 21.05
r 7 = -33.95 d 7 = 2.20 n 4 = 1.498 ν 4 = 81.5
r 8 = -52.61 d 8 = variable
r 9 = -85.31 d 9 = 3.00 n 5 = 1.776 ν 5 = 49.6
r10 = 84.44 d10 = variable
r11 = 233.02 d11 = 2.30 n 6 = 1.932 ν 6 = 20.9
r12 = 78.82 d12 = 9.91 n 7 = 1.910 ν 7 = 31.3
r13 = -63.44 d13 = variable
r14 = 64.77 d14 = 4.82 n 8 = 1.766 ν 8 = 40.1
r15 = -2675.45 d15 = variable
r16 = 378.47 d16 = 3.77 n 9 = 1.518 ν 9 = 64.1
r17 = -25.13 d17 = 1.54 n10 = 1.888 ν10 = 40.8
r18 = -48.67 d18 = variable
STr19 = ∞ d19 = variable
r20 = -417.00 d20 = 1.50 n11 = 1.856 ν11 = 32.3
r21 = 23.85 d21 = 6.33 n12 = 1.518 ν12 = 64.1
r22 = -19.41 d22 = 1.64
r23 = -17.15 d23 = 2.00 n13 = 1.910 ν13 = 31.3
r24 = 70.87 d24 = 4.52 n14 = 1.489 ν14 = 70.2
r25 = -41.99 d25 = 1.35
r26 = 385.82 d26 = 8.62 n15 = 1.498 ν15 = 81.5
r27 = -23.21 d27 = variable
r28 = 86.39 d28 = 4.47 n16 = 1.902 ν16 = 20.4
r29 = -181.32 d29 = 2.00
r30 = ∞ d30 = 22.40 n17 = 1.516 ν17 = 64.1
r31 = ∞ d31 = 17.7 n18 = 1.805 ν18 = 25.4
r32 = ∞ d32 = 7.2

When zoomed (1205mm) When focused (wide-angle end)
Group spacing Wide angle Telephoto Group spacing 861mm 1205mm 3443mm
d13 23.06 0.59 d 2 13.95 14.15 14.26
d15 35.74 45.69 d 8 5.41 6.87 6.52
d18 1.50 2.61 d10 10.03 9.79 9.91
d19 6.48 2.55 d13 24.48 23.06 23.18
d27 1.50 16.84

Aspheric coefficient
r1 K = 0 A = 6.35E-06 B = -5.69E-09 C = 6.95E-12 D = -5.99E-15
E = 3.40E-18 F = -1.09E-21 G = 1.75E-25
r5 K = 0 A = -1.44E-05 B = 3.89E-08 C = -4.42E-11 D = 9.18E-15
E = -4.74E-18 F = 4.61E-20 G = -3.47E-23
r6 K = 0 A = -7.66E-06 B = 2.47E-08 C = 2.02E-11 D = -9.74E-14
E = 5.75E-17 F = -2.08E-19 G = 4.57E-22

<Example 3>

Lens configuration
f (focal length) 12.62
F (aperture ratio) 2.80
Projection half angle of view (degrees) 45.8
Total lens length 190.0
BF 59.2

* r 1 = 212.51 d 1 = 3.60 n 1 = 1.727 ν 1 = 53.1
r 2 = 45.65 d 2 = variable
r 3 = 285.25 d 3 = 3.27 n 2 = 1.489 ν 2 = 70.2
r 4 = -963.92 d 4 = 2
* r 5 = 447.06 d 5 = 2.78 n 3 = 1.921 ν 3 = 40.3
* r 6 = 36.41 d 6 = 33.44
r 7 = -44.38 d 7 = 2.20 n 4 = 1.498 ν 4 = 81.5
r 8 = 56.30 d 8 = variable
r 9 = -980.56 d 9 = 2.20 n 5 = 1.888 ν 5 = 40.8
r10 = 191.06 d10 = variable
r11 = 113.00 d11 = 2.30 n 6 = 1.932 ν 6 = 20.9
r12 = 54.55 d12 = 9.68 n 7 = 1.910 ν 7 = 31.3
r13 = -60.51 d13 = variable
r14 = 70.47 d14 = 3.56 n 8 = 1.766 ν 8 = 40.1
r15 = -5238.45 d15 = 26.02179849
r16 = 658.20 d16 = 3.73 n 9 = 1.518 ν 9 = 64.1
r17 = -25.95 d17 = 1.75 n10 = 1.888 ν10 = 40.8
r18 = -45.93 d18 = 3.249925267
STr19 = ∞ d19 = 8.757922323
r20 = 852.10 d20 = 1.50 n11 = 1.856 ν11 = 32.3
r21 = 20.50 d21 = 6.94 n12 = 1.518 ν12 = 64.1
r22 = -20.37 d22 = 1.74
r23 = -17.49 d23 = 2.00 n13 = 1.910 ν13 = 31.3
r24 = 80.93 d24 = 4.37 n14 = 1.489 ν14 = 70.2
r25 = -47.35 d25 = 1.34
r26 = 437.79 d26 = 9.06 n15 = 1.498 ν15 = 81.5
r27 = -22.91 d27 = 1.500000568
r28 = 104.96 d28 = 4.47 n16 = 1.902 ν16 = 20.4
r29 = -141.93 d29 = 2.00
r30 = ∞ d30 = 22.40 n17 = 1.516 ν17 = 64.1
r31 = ∞ d31 = 17.7 n18 = 1.805 ν18 = 25.4
r32 = ∞ d32 = 7.2

During focus
Group spacing 861mm 1205mm 3443mm
d 2 14.16 13.97 13.73
d 8 6.19 5.76 5.03
d10 2.50 2.76 3.21
d13 25.68 26.04 26.55

Aspheric coefficient
r1 K = 0 A = 6.01E-06 B = -5.57E-09 C = 7.07E-12 D = -6.03E-15
E = 3.21E-18 F = -9.12E-22 G = 1.25E-25
r5 K = 0 A = -1.27E-05 B = 3.83E-08 C = -4.61E-11 D = 1.29E-14
E = 1.32E-18 F = 2.44E-20 G = -2.05E-23
r6 K = 0 A = -5.22E-06 B = 2.24E-08 C = 2.91E-11 D = -1.03E-13
E = 4.39E-17 F = -1.30E-19 G = 3.16E-22

B1 1st lens group B2 2nd lens group B3 3rd lens group B4 4th lens group B5 5th lens group B1a, B1b, B1c, B1d Partial group

Claims (13)

In an optical system composed of a first lens group having a negative refractive power and a rear group including one or more lens groups in order from the magnification conjugate side to the reduction conjugate side,
The first lens unit includes, in order from the magnification conjugate side to the reduction conjugate side, a negative refractive power subgroup B1a, a negative refractive power subgroup B1b, a negative refractive power subgroup B1c, and a positive refractive power subgroup. B1d, the subgroup B1a does not move during focusing from infinity to the nearest, and the subgroup B1b, the subgroup B1c, and the subgroup B1d are all on the reduction conjugate side, and the subgroup B1b and the subgroup An optical system that moves while decreasing the distance between the subgroup B1c and the subgroup B1d while enlarging the distance between the subgroup B1c. When the focal length of the partial group B1b is fB1b, and the focal length of the first lens group when focusing on infinity is fB1,
0.2 <fB1b / fB1 <0.9
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the subgroup B1b is fB1b, and the focal length of the combined system of the subgroup B1c and the subgroup B1d when focusing on infinity is fB1cd,
−8.0 <fB1cd / fB1b <−1.0
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the subgroup B1c is fB1c and the focal length of the subgroup B1d is fB1d,
-6.0 <fB1c / fB1d <0.0
The optical system according to claim 1, wherein the following conditional expression is satisfied.   The optical system according to any one of claims 1 to 4, wherein the partial group B1b includes one or more positive lenses.   The optical system according to claim 1, wherein the partial group B1d includes one or more cemented lenses.   The optical system according to any one of claims 1 to 6, wherein the partial group B1a has an aspheric lens surface.   The optical system according to any one of claims 1 to 7, wherein the subgroup B1c includes at least one negative lens.   The optical system according to any one of claims 1 to 8, wherein the subgroup B1b includes a plurality of negative lenses.   The optical system according to claim 1, wherein the rear group includes a lens group having a positive refractive power.   The optical system is a zoom lens, and the rear group in order from the magnification conjugate side to the reduction conjugate side is a second lens group having a positive refractive power, a third lens group having a positive refractive power, and a first lens having a negative refractive power. The zoom lens is composed of four lens groups and a fifth lens group having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group and the fifth lens group do not move, and the second lens group and the second lens group do not move. The optical system according to any one of claims 1 to 10, wherein the three lens groups and the fourth lens group move to the magnification conjugate side along different paths.   An optical system according to any one of claims 1 to 11, and an image display element that forms an original image, and the original image formed by the image display element is projected by the optical system. Image projection device. When the maximum projection half angle of view of the optical system is ω (degrees),
39.0 ° <ω <55.0 °
The image projection apparatus according to claim 12, wherein the following conditional expression is satisfied.