JP5611901B2 - Variable magnification optical system for projection and projection display device - Google Patents

Description

  The present invention relates to a projection variable magnification optical system and a projection display device, and more particularly to a projection variable magnification optical system suitable for projection on a large screen in a movie theater or the like and a projection display device using the same. Is.

  2. Description of the Related Art Conventionally, projection projector apparatuses (projection display apparatuses) using light valves such as liquid crystal display elements and DMD (Digital Micromirror Device: registered trademark) have been widely used. In recent years, movie projectors and the like are also using such projection display devices that can project higher-definition images that can be applied to large screens. In the projection display device used for such a use, three light valves are provided for each primary color, the light flux from the light source is separated into the three primary colors by the color separation optical system, and each light valve passes through. Later, since a three-plate method of combining and projecting with a color combining optical system is adopted, it is required to have a long back focus and good telecentricity.

  Generally, the value obtained by dividing the projection distance by the screen width is called the slow ratio. The screen size and the distance from the screen to the projection room, that is, the projection distance varies from movie theater to movie theater. Therefore, in order to project an image having a size suitable for each movie theater, a lens corresponding to a slow ratio suitable for each movie is required. However, it is not a good idea to prepare them individually from the viewpoint of cost. In view of this, it is conceivable to use a variable magnification optical system to provide a wide range of possible slow ratios. As variable power optical systems for projection, for example, those described in Patent Documents 1 to 3 below are known.

  However, in many of the conventional variable magnification optical systems for projection, the numerical aperture (hereinafter sometimes referred to as “F number”) changes during magnification. Normally, the telephoto side has a larger F-number than the wide side, so in such a variable magnification optical system, even in a movie theater of the same screen size, a movie with a large slow ratio will be darker. For movie theater use, it is preferable that the F number is constant during zooming. Therefore, the applicant of the present application is set in Patent Document 4 below so that the F number is constant during zooming. A zoom lens for projection is proposed.

JP 2010-008797 A JP 2007-271669 A JP 2010-282147 A JP 2010-152277 A

  In order to increase the width of the slow ratio, it is desirable that the variable magnification optical system has a high variable magnification ratio. However, the projection zoom lenses described in Patent Documents 1 to 3 have a zoom ratio of about 1.2 to 1.3, and do not meet the demand for a high zoom ratio. The zoom lens for projection described in Patent Document 4 has a zoom ratio of about 1.4 to 1.55, but in recent years, a higher zoom ratio may be required. In the conventional projection zoom lens described above, when trying to obtain an image circle diameter suitable for cinema use (hereinafter also referred to as the maximum effective image circle diameter) while achieving the above-described demand and a high zoom ratio, There arises a problem that performance deterioration at the time of zooming and an increase in size of the optical system are caused.

  The present invention has been made in view of such circumstances, and while having an appropriate back focus and a large zoom ratio, fluctuations in aberrations during zooming and enlargement of the entire system are suppressed. Accordingly, it is an object of the present invention to provide a telecentric variable power optical system for projection and a projection display device that can easily widen the angle and have a constant F number during variable power.

In order to achieve the above object, a first projection variable-power optical system according to the present invention includes a first lens group that has a negative refractive power that is disposed closest to the enlargement side and is fixed during zooming. The lens is disposed between the first lens group and the final lens group, which is disposed on the most reduction side and has a positive refractive power that is fixed when zooming, and moves when zooming. The lens is substantially composed of a plurality of lens groups, and the most magnified lens group among the plurality of lens groups moving during zooming has negative refractive power, and the reduction side is telecentric, and the final lens A diaphragm is disposed in the group, the numerical aperture is set to be constant over the entire range of zooming, and the following conditional expressions (1) to (3) are satisfied.
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
However,
L: Distance on the optical axis from the most enlarged lens surface to the most reduced lens surface at an infinite projection distance Imφ: Maximum effective image circle diameter on the reduction side Bf: Back on the reduction side of the entire system at the wide angle end Focus (Air equivalent distance)
Zr: zoom ratio of the telephoto end with respect to the wide angle end f: focal length of the entire system at the wide angle end
In order to achieve the above object, the second projection variable magnification optical system according to the present invention is a first lens having a negative refractive power that is disposed on the most enlarged side and is fixed at the time of variable magnification. A group, a final lens group having a positive refractive power that is arranged on the most reduction side and fixed at the time of zooming, and a first lens group and a final lens group that are arranged at the time of zooming. It consists essentially of a plurality of moving lens groups, the reduction side is telecentric, a diaphragm is arranged in the final lens group, and the numerical aperture is set to be constant over the entire zoom range. The following conditional expressions (1) to (3) and (6) are satisfied.
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
-10.0 <f1 / f <-2.0 (6)
However,
L: Distance on the optical axis from the most magnified lens surface to the most reduced lens surface at an infinite projection distance
Imφ: Maximum effective image circle diameter on the reduction side
Bf: Back focus on the reduction side of the entire system at the wide angle end (air conversion distance)
Zr: zoom ratio of telephoto end to wide angle end
f: focal length of the entire system at the wide angle end
f1: Focal length of the first lens group
In order to achieve the above object, the third projection variable magnification optical system according to the present invention is a first lens having a negative refractive power that is disposed on the most enlarged side and is fixed at the time of variable magnification. A group, a final lens group having a positive refractive power that is arranged on the most reduction side and fixed at the time of zooming, and a first lens group and a final lens group that are arranged at the time of zooming. It consists essentially of a plurality of moving lens groups, the reduction side is telecentric, a diaphragm is arranged in the final lens group, and the numerical aperture is set to be constant over the entire zoom range. The following conditional expressions (1) to (3) and (8) are satisfied.
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
1.4 <Zr (8)
However,
L: Distance on the optical axis from the most magnified lens surface to the most reduced lens surface at an infinite projection distance
Imφ: Maximum effective image circle diameter on the reduction side
Bf: Back focus on the reduction side of the entire system at the wide angle end (air conversion distance)
Zr: zoom ratio of telephoto end to wide angle end
f: focal length of the entire system at the wide angle end

In the projection variable magnification optical system according to the present invention, it is preferable that any one of the following conditional expressions (4) to (8) or any combination is satisfied.
enP / f + f / Bf <3.7 (4)
1.8 <Bf / Imφ (5)
-10.0 <f1 / f <-2.0 (6)
30 <| exP | / Imφ (7)
1.4 <Zr (8)
However,
enP: Distance on the optical axis from the most magnified lens surface to the entrance pupil position at the wide angle end when the projection distance is infinity when the magnification side is the incident side f1: Focal length exP of the first lens group: reduction Distance on the optical axis from the reduced-side image plane to the paraxial exit pupil position at the wide-angle end when the projection distance is infinity when the side is the exit side

  Further, in the projection variable magnification optical system according to the present invention, the plurality of lens groups that move during the magnification change can be configured to substantially consist of two or three lens groups.

  Further, in the projection variable magnification optical system according to the present invention, it is preferable that the most magnified lens group among the plurality of lens groups moving during zooming has a negative refractive power.

In the projection variable magnification optical system according to the present invention, it is preferable that all the lenses on the reduction side of the first lens group are single lenses .

  The projection variable magnification optical system according to the present invention is preferably configured to be a zoom lens by changing only the distance between the lens groups.

  In addition, when the projection variable magnification optical system according to the present invention is a zoom lens, focusing is performed on only a part of the first lens group including the lens arranged closest to the reduction side of the first lens group in the optical axis direction. It is preferable to be configured so as to be performed by an inner focus method of moving to the position.

  A projection display device according to the present invention is a projection variable power optical system that projects a light source, a light valve on which light from the light source is incident, and an optical image by light modulated by the light valve onto a screen. The projection variable magnification optical system of the present invention described above is provided.

  The zooming optical system for projection according to the present invention may be a zoom lens or a varifocal lens.

  The “enlarged side” means the projected side (screen side), and the screen side is also referred to as the enlarged side for the sake of convenience when performing reduced projection. On the other hand, the “reduction side” means the original image display area side (light valve side), and the light valve side is also referred to as the reduction side for the sake of convenience when performing reduced projection.

  Note that the phrase “consisting essentially of” and “substantially consisting of two or three lens groups” substantially has power other than the lens groups mentioned as the constituent elements. It means that there are no lenses or lens groups, and those having optical elements other than lenses such as a diaphragm and a cover glass.

  Note that “the reduction side is telecentric” means that the bisector of the upper maximum ray and the lower maximum ray is parallel to the optical axis in the cross section of the light beam condensed at an arbitrary point on the reduction side image plane. Is not limited to the case where it is completely telecentric, that is, the case where the bisector is completely parallel to the optical axis, and includes cases where there are some errors. means. Here, the case where there is a slight error is a case where the inclination of the bisector with respect to the optical axis is within ± 3 °.

  The “lens group” does not necessarily include a plurality of lenses but also includes a single lens.

  The “Imφ” can be obtained, for example, according to the specifications of the projection variable magnification optical system or the specifications of the apparatus in which the projection variable magnification optical system is mounted.

  The “single lens” means a single lens that is not joined.

  The zooming optical system for projection according to the present invention includes, in order from the magnification side, a first lens group having a negative refractive power that is fixed during zooming, a plurality of lens groups that move during zooming, A final lens group having a positive refractive power that is fixed at the time of magnification is arranged, the reduction side is telecentric, and satisfies a predetermined conditional expression, so that a wide angle is achieved while having an appropriate back focus. This makes it easy to control aberration fluctuations and enlargement of the entire system while maintaining a large zoom ratio. For example, a zoom ratio suitable for movie theater applications and the size of an image circle can be achieved. can do.

  Further, the projection variable magnification optical system according to the present invention is configured such that, in the above-described lens group configuration, a stop is disposed in the final lens group, and the numerical aperture is constant over the entire range of variable magnification. Therefore, if the projection magnification is the same, the brightness of the projection screen can be made constant regardless of the projection distance, and can be suitable for movie theater use, for example.

  Since the projection display apparatus according to the present invention includes the projection variable magnification optical system according to the present invention, the projection display apparatus can be used with a large variable magnification ratio without extremely increasing the size of the apparatus. Good projection images can be obtained over a wide range, which is suitable for movie theater use, for example.

Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 1 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 1 of this invention. Sectional drawing which shows the lens structure and light ray locus | trajectory of the projection variable magnification optical system which concerns on Example 2 of this invention. The figure which shows arrangement | positioning of a lens group and a light ray locus | trajectory in each position at the time of zooming of the zooming optical system for projection which concerns on Example 2 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 3 of this invention. FIG. 6 is a diagram showing the arrangement of lens groups and the ray trajectory at each position during zooming in the zooming optical system for projection according to Example 3 of the present invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 4 of this invention. FIG. 10 is a diagram showing the arrangement of lens groups and the ray trajectory at each position during zooming in the zooming optical system for projection according to Example 4 of the present invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 5 of this invention. The figure which shows arrangement | positioning of a lens group and a light ray locus | trajectory in each position at the time of zooming of the zooming optical system for projection which concerns on Example 5 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 6 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 6 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 7 of this invention. The figure which shows arrangement | positioning of a lens group and a light ray locus | trajectory in each position at the time of zooming of the zooming optical system for projection which concerns on Example 7 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 8 of this invention. The figure which shows arrangement | positioning of a lens group and a light ray locus | trajectory in each position at the time of zooming of the zooming optical system for projection which concerns on Example 8 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 9 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 9 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 10 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 10 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 11 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 11 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 12 of this invention. The figure which shows arrangement | positioning of a lens group and a light ray locus | trajectory in each position at the time of zooming of the zooming optical system for projection which concerns on Example 12 of this invention. Sectional drawing which shows the lens structure and light ray locus of the variable magnification optical system for projection which concerns on Example 13 of this invention. The figure which shows arrangement | positioning of a lens group in each position at the time of zooming, and a light ray locus | trajectory of the zooming optical system for projection which concerns on Example 13 of this invention. FIGS. 27A to 27L are aberration diagrams of the variable power optical system for projection according to Example 1 of the present invention. FIGS. 28A to 28L are graphs showing aberrations of the variable power optical system for projection according to Example 2 of the present invention. FIGS. 29A to 29L are aberration diagrams of the projection variable-power optical system according to Example 3 of the present invention. 30 (A) to 30 (L) are graphs showing various aberrations of the projection variable-power optical system according to Example 4 of the present invention. 31 (A) to 31 (L) are graphs showing aberrations of the projection variable-power optical system according to Example 5 of the present invention. 32 (A) to 32 (L) are graphs showing aberrations of the projection variable magnification optical system according to Example 6 of the present invention. 33 (A) to 33 (L) are graphs showing various aberrations of the projection variable magnification optical system according to Example 7 of the present invention. 34 (A) to 34 (L) are graphs showing various aberrations of the projection variable-power optical system according to Example 8 of the present invention. 35 (A) to 35 (L) are graphs showing aberrations of the projection variable magnification optical system according to Example 9 of the present invention. 36 (A) to 36 (L) are graphs showing aberrations of the projection variable magnification optical system according to Example 10 of the present invention. FIGS. 37A to 37L are aberration diagrams of the variable power optical system for projection according to Example 11 of the present invention. FIGS. 38A to 38L are aberration diagrams of the projection variable magnification optical system according to Example 12 of the present invention. 39 (A) to 39 (L) are aberration diagrams of the variable magnification optical system for projection according to Example 13 of the present invention. 1 is a schematic configuration diagram of a projection display device according to an embodiment of the present invention. Schematic configuration diagram of a projection display device according to another embodiment of the present invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a variable power optical system for projection according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a lens configuration at the wide-angle end of a projection variable-power optical system according to Embodiment 1 of the present invention, and FIG. 2 is a diagram when the projection variable-power optical system shown in FIG. 4 shows the movement positions of the lens units at the wide-angle end, the intermediate focal position, and the telephoto end. In FIG. 2, the moving direction of the moving lens group when changing from the wide-angle end to the intermediate focus position and from the intermediate focus position to the telephoto end is schematically shown by arrows between the positions. Both FIG. 1 and FIG. 2 also show the ray trajectories on the on-axis and off-axis. In the following, embodiments of the present invention will be described with the configuration examples shown in FIGS. 1 and 2 as representative examples.

  The projection variable magnification optical system can be mounted on a projection display device for projecting a digital image used in a movie theater or the like. For example, projection for projecting image information displayed on a light valve onto a screen. It can be used as a lens. In FIG. 1 and FIG. 2, assuming that the left side of the drawing is the enlargement side and the right side is the reduction side and is mounted on a projection display device, glass blocks 2a and 2b such as color synthesis prisms (including filters) and the like. The image display surface 1 of the light valve located on the reduction side surface of the glass block 2b is also shown.

  In the projection display device, a light beam given image information on the image display surface 1 is incident on the projection variable optical system via the glass blocks 2a and 2b, and the paper surface is projected by the projection variable optical system. The image is enlarged and projected on a screen (not shown) arranged in the left direction.

  1 and 2 show an example in which the position of the reduction-side surface of the glass block 2b matches the position of the image display surface 1, but the present invention is not necessarily limited to this. 1 and 2 show only one image display surface 1, in the projection display device, the light flux from the light source is separated into three primary colors by a color separation optical system, and each of the primary colors is used. Alternatively, three light valves may be provided so that a full-color image can be displayed.

  The projection variable magnification optical system according to this embodiment includes a first lens group G1 having a negative refractive power that is disposed on the most magnification side and fixed at the time of magnification change, and is disposed on the most reduction side and varies. A final lens group having a positive refractive power fixed at the time of magnification, and a plurality of lens groups (hereinafter referred to as a variable lens) disposed between the first lens group G1 and the final lens group and moving at the time of zooming. Only the double-moving lens group) as a substantial lens group, and the reduction side is configured to be telecentric.

  In this way, it is advantageous to obtain a wide angle of view by making the first lens group G1 closest to the enlargement side a negative lens group.

  For example, in the example shown in FIGS. 1 and 2, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are sequentially arranged from the enlargement side. Five lens groups are arranged. Among these, the three lens groups of the second lens group G2, the third lens group G3, and the fourth lens group G4 correspond to the moving lens group during zooming, and the fifth lens group G5 corresponds to the final lens group.

  Note that the number of moving lens groups at the time of zooming of the zooming optical system for projection according to the present invention is not limited to three, and can be selected as appropriate, and may be two, for example. If the moving lens unit at the time of zooming is composed of two or three lens units, it becomes easy to suppress both the enlargement of the entire system and aberration fluctuations at the time of zooming.

  Of the moving lens groups at the time of zooming, it is preferable that the most magnified lens group has a negative refractive power. The first lens group G1 is a negative lens group, and the lens group on the most magnifying side of the zooming moving lens group is also a negative lens group, so that the lens diameter on the magnifying side is appropriately increased while obtaining a wide angle of view. In addition, it becomes easy to obtain a high zoom ratio.

  1 and 2 has a negative, positive, and positive power array in order from the enlargement side. With this configuration, an image can be obtained over the entire zoom range. It becomes easy to correct the surface curvature. When the entire system is composed of five groups and the power array is negative, negative, positive, positive, and positive in order from the magnification side, the wide-angle lens system to the medium telephoto lens system have a long back focus and a large zoom ratio. It is easy to realize a wide range.

  In the example shown in FIGS. 1 and 2, the first lens group G1 includes five lenses (the first lens L1 to the fifth lens L5), and the second lens group G2 has 2 lenses. The third lens group G3 is composed of two lenses (eighth lens L8 and ninth lens L9), and the fourth lens group G4 is composed of two lenses (sixth lens L6, seventh lens L7). The fifth lens group G5 includes a diaphragm 3 and six lenses (a twelfth lens L12 to a seventeenth lens L17). However, the number of lenses constituting each lens group of the projection variable magnification optical system of the present invention is not necessarily limited to the examples shown in FIGS.

  The projection variable magnification optical system of the present embodiment has a diaphragm 3 disposed in the final lens group, and is set so that the numerical aperture is constant over the entire range of variable magnification. As the diaphragm 3, for example, a diaphragm that functions as an aperture diaphragm can be used.

  By disposing the diaphragm 3 on the reduction side with respect to all the lens groups that move at the time of zooming, even if the diaphragm 3 is a fixed diaphragm having a simple fixed aperture that does not change the diaphragm diameter, If the numerical aperture is constant and the projection magnification is the same, the image can be projected on the screen with the same brightness regardless of the projection distance. For example, it is effective when the projection distance is changed according to the size or shape of the indoor space of a movie theater or the like. Of course, a variable aperture having a variable aperture diameter can be used as the aperture 3.

In addition, the projection variable magnification optical system of the present embodiment is configured to satisfy the following conditional expressions (1) to (3).
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
However,
L: Distance on the optical axis from the most enlarged lens surface to the most reduced lens surface at an infinite projection distance Imφ: Maximum effective image circle diameter on the reduction side Bf: Back on the reduction side of the entire system at the wide angle end Focus (Air equivalent distance)
Zr: zoom ratio of the telephoto end with respect to the wide-angle end f: focal length of the entire system at the wide-angle end

  Conditional expression (1) is the maximum effective image circle diameter, so-called image circle size, and the distance on the optical axis from the most magnified lens surface to the most demagnifying lens surface (hereinafter referred to as lens) when the projection distance is infinite. The total thickness)). If the upper limit of conditional expression (1) is exceeded, the desired size of the image circle cannot be obtained, and it is difficult to provide a function necessary as a projection variable magnification optical system for a movie theater or the like intended by the present invention. Or the total lens thickness is too large.

  Conditional expression (2) defines the relationship between the back focus, the size of the image circle, and the zoom ratio. If the lower limit of conditional expression (2) is not reached, at least one of the following problems occurs: an appropriate back focus cannot be obtained, a high zoom ratio cannot be obtained, and the lens system is enlarged. It is difficult to provide a function necessary for a projection variable magnification optical system for use in a movie theater or the like.

  Conditional expression (3) defines the relationship among the size of the image circle, the back focus, the zoom ratio, the focal length, and the total lens thickness. If the lower limit of conditional expression (3) is not reached, it will be difficult to maintain all these values at the same time, an appropriate back focus cannot be obtained, a high zoom ratio cannot be obtained, and the lens system will be enlarged. Thus, at least one defect occurs, and it becomes difficult to provide a function necessary as a projection variable-power optical system for a movie theater or the like intended by the present invention.

  In addition, it is preferable that the projection variable magnification optical system according to the present embodiment further has the following configurations as appropriate. In addition, as a preferable aspect, it may have one of the structures described below, or may have any combination.

It is preferable that the projection variable magnification optical system of the present embodiment satisfies any one of the following conditional expressions (4) to (8), or any combination.
enP / f + f / Bf <3.7 (4)
1.8 <Bf / Imφ (5)
-10.0 <f1 / f <-2.0 (6)
30 <| exP | / Imφ (7)
1.4 <Zr (8)
However,
enP: Distance on the optical axis from the most magnified lens surface at the wide-angle end to the entrance pupil position at the wide-angle end when the projection distance is infinity when the enlargement side is the entrance side f: Focal length Bf of the entire system at the wide-angle end Back focus on the reduced side of the entire system at the wide-angle end (air equivalent distance)
Imφ: Maximum effective image circle diameter f1 on the reduction side f1: Focal length exP of the first lens group G1: Paraxial from the imaging surface on the reduction side at the wide angle end when the projection distance is infinite when the reduction side is the exit side Distance Zr on optical axis to exit pupil position: zoom ratio at telephoto end with respect to wide-angle end

  Conditional expression (4) relates to the entrance pupil position and the back focus. When the upper limit of conditional expression (4) is exceeded, the distance from the most magnified lens surface to the entrance pupil position becomes longer, the enlarged lens diameter of the first lens group G1 becomes larger, or an appropriate back focus is obtained. I can't get it.

  Conditional expression (5) relates to the ratio between the back focus and the size of the image circle. Conditional expression (5) makes it possible to secure an appropriate space for inserting a glass block or the like as a color composition means such as a beam splitter, a cross dichroic prism, or a TIR prism while obtaining a desired image circle size. It is what. That is, if the lower limit of conditional expression (5) is not reached, it will be difficult to insert a glass block or the like as a color composition means on the reduction side of the lens system.

  Conditional expression (6) defines the power of the first lens group G1. If the lower limit of conditional expression (6) is not reached, the outer diameter of the lens on the enlargement side becomes large, making it difficult to widen the angle, and it becomes difficult to ensure a long back focus. It becomes difficult to insert a glass block or the like. Exceeding the upper limit of conditional expression (6) makes it difficult to correct curvature of field and distortion.

  Conditional expression (7) relates to the exit pupil position and the size of the image circle. If the lower limit of conditional expression (7) is not reached, it is difficult to ensure telecentricity while obtaining the desired image circle size.

  Conditional expression (8) defines the zoom ratio. If the lower limit of conditional expression (8) is not reached, a high zoom ratio cannot be obtained, the range that can be used as a zooming optical system for projection is narrowed, and the cost merit is reduced. It cannot be said that it is suitable as a projection variable magnification optical system for such applications.

From the above circumstances, it is more preferable that the following conditional expressions (1-1) to (8-1) are satisfied instead of the conditional expressions (1) to (8).
L / Imφ <11.0 (1-1)
5.5 <(Bf × Zr ² ) / Imφ (2-1)
0.57 <(Imφ × Bf × Zr ² ) / (f × L) (3-1)
enP / f + f / Bf <3.6 (4-1)
2.2 <Bf / Imφ (5-1)
−7.0 <f1 / f <−2.5 (6-1)
35 <| exP | / Imφ (7-1)
1.5 <Zr (8-1)

  In the projection variable magnification optical system according to the present embodiment, it is preferable that all the lenses on the reduction side of the first lens group are constituted by single lenses instead of cemented lenses. On the reduction side of the first lens group, there are many portions where the on-axis light beam and off-axis light beam overlap, so that when the projection variable magnification optical system is mounted on the projection display device and used in combination with a high-output light source, However, there is a possibility that the bonding agent for bonding the lens may be significantly deteriorated and deteriorated, resulting in a decrease in lens performance. However, by not using the bonding lens, it is possible to avoid the occurrence of such a problem. In order to avoid the occurrence of such a problem as much as possible, it is more preferable that all the lenses in the entire system are constituted by a single lens instead of a cemented lens.

  In the variable power optical system for projection according to the present embodiment, as in the example shown in FIG. 1, it is possible to employ a configuration without using an aspheric surface in which each lens surface is a spherical surface. This is advantageous in terms of cost. Of course, the projection variable magnification optical system of the present embodiment can be configured to use an aspherical surface, and in this case, aberration correction can be performed more satisfactorily.

  Further, the projection variable magnification optical system of the present embodiment may be configured to be a zoom lens by changing only the distance between the lens groups. In other words, the zoom lens may be converted to the varifocal lens or the varifocal lens to the zoom lens by changing only the distance between the lens groups. According to such a configuration, it can be used for different focus type devices with a minimum change in the mechanism structure, and the cost merit can be increased.

  When the projection variable magnification optical system is a zoom lens, focusing when the projection distance is changed is part of the first lens group G1 including the lens arranged closest to the reduction side of the first lens group 1. It is preferable to adopt an inner focus method in which only the lens is moved in the optical axis direction.

  For example, in the example shown in FIG. 1, focusing can be performed by moving one lens L5 closest to the reduction side of the first lens group G1 in the optical axis direction. By adopting the inner focus method, it is not necessary to drive the enlargement side lens having a large diameter and a large weight, so that the load on the drive mechanism can be reduced and the entire lens thickness can be kept constant during focusing.

  In the variable power optical system for projection according to the present invention, focusing can be performed by moving the entire first lens group G1 or a part other than the reduction side, or other than the first lens group G1. It is also possible to move by moving all or part of the lens group.

  The projection variable magnification optical system that is the object of the present invention is preferably an optical system having an F number smaller than 3.0 in the entire variable magnification range. Further, in the variable power optical system for projection targeted by the present invention, it is preferable that distortion (distortion aberration) is suppressed to about 2% or less in the entire variable power range.

  Next, an embodiment of a projection display apparatus according to the present invention will be described with reference to FIGS. FIG. 40 is a schematic configuration diagram showing a part of a projection display apparatus according to an embodiment of the present invention, and FIG. 41 is a schematic configuration diagram showing a part of a projection display apparatus according to another embodiment of the present invention. It is.

  The projection display device shown in FIG. 40 includes reflective display elements 11a to 11c as light valves corresponding to each color light, dichroic mirrors 12 and 13 for color separation, and a cross dichroic prism 14 for color composition. The illumination optical system 10 includes a total reflection mirror 18 for deflecting the optical path and polarization separation prisms 15a to 15c. Note that a light source (not shown) is disposed in front of the dichroic mirror 12.

  White light from the light source is decomposed into three colored light beams (G light, B light, and R light) by the dichroic mirrors 12 and 13. The separated color light beams pass through the polarization separation prisms 15a to 15c, enter the corresponding reflective display elements 11a to 11c, are light-modulated, and are color-combined by the cross dichroic prism 14, and then the above-mentioned. The incident light enters the projection variable magnification optical system 19 according to the embodiment. The optical image by the incident light is projected on a screen (not shown) by the projection variable magnification optical system 19.

  On the other hand, a projection display apparatus according to another embodiment shown in FIG. 41 includes reflective display elements 21a to 21c as light valves corresponding to each color light, and TIR (Total Internal Reflection) for color separation and color synthesis. An illumination optical system 20 having prisms 24 a to 24 c and a polarization separation prism 25 is provided. Note that a light source (not shown) is disposed in front of the polarization separation prism 25.

  The white light from the light source passes through the polarization separation prism 25 and is then decomposed into three color light beams (G light, B light, and R light) by the TIR prisms 24a to 24c. The separated color light beams are incident on the corresponding reflective display elements 21a to 21c to be light-modulated, proceed again in the opposite directions through the TIR prisms 24a to 24c, and are color-synthesized, and then transmitted through the polarization separation prism 25. Then, the light enters the projection variable magnification optical system 29 according to the above-described embodiment. An optical image by the incident light is projected on a screen (not shown) by the projection variable magnification optical system 29.

  In addition, as the reflective display elements 11a to 11c and 21a to 21c, for example, a reflective liquid crystal display element, DMD, or the like can be used. 40 and 41 show an example in which a reflective display element is used as a light valve. However, the light valve provided in the projection display device of the present invention is not limited to this, and a transmissive liquid crystal display element or the like is used. A transmissive display element may be used.

  Next, specific examples of the projection variable magnification optical system according to the present invention will be described. Examples 1 to 13 described below are configured as varifocal lenses, but Examples 1 and 11 can be used as zoom lenses by changing only the distance between lens groups, as will be described later as modified examples. It is configured as follows. When Examples 1 to 13 are used as varifocal lenses, focusing when zooming or when the projection distance is changed is performed by an entire payout system in which the entire system is integrally moved in the optical axis direction. .

<Example 1>
FIG. 1 and FIG. 2 show the lens configuration and ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 1, respectively, the arrangement of lens groups and ray trajectory at each position during zooming. The configurations shown in FIGS. 1 and 2 are those when the reduction ratio is −0.002 times. Since the detailed description of FIGS. 1 and 2 is as described above, a part of the overlapping description is omitted here.

  The variable power optical system for projection of Example 1 includes, in order from the magnification side, a first lens group G1 having a negative refractive power, a second lens group G2 having a negative refractive power, and a first lens group having a positive refractive power. This is a five-group configuration in which a three-lens group G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power are arranged, and the reduction side is telecentric. On the reduction side of the lens group G5, glass blocks 2a and 2b such as an image display surface 1 of a light valve composed of a reflective liquid crystal display panel and a color synthesis prism (including filters such as an infrared cut filter and a low-pass filter) are disposed. Has been.

  At the time of zooming, the first lens group G1 and the fifth lens group G5 are fixed, the second lens group G2, the third lens group G3, and the fourth lens group G4 are movable. It is represented. Further, the numerical aperture is set to be constant over the entire range of zooming.

  The first lens group G1, in order from the magnifying side, a first lens L1 made of a positive meniscus lens having a convex surface on the magnifying side, a second lens L2 made of a negative meniscus lens having a concave surface on the reducing side, The lens includes a third lens L3 made of a plano-concave lens having a concave surface facing the reduction side, a fourth lens L4 made of a biconcave lens, and a fifth lens L5 made of a positive meniscus lens having a convex surface facing the reduction side. .

  The second lens group G2 includes, in order from the enlargement side, a sixth lens L6 made of a biconcave lens and a seventh lens L7 made of a biconvex lens. The third lens group G3 includes, in order from the enlargement side, an eighth lens L8 made of a negative meniscus lens having a convex surface directed toward the reduction side, and a ninth lens L9 made of a biconvex lens. The fourth lens group G4 includes, in order from the magnification side, a tenth lens L10 made of a negative meniscus lens having a convex surface directed toward the magnification side, and an eleventh lens L11 made of a biconvex lens.

  The fifth lens group G5 has an aperture (including an aperture and a variable aperture) 3 in order from the magnification side, a twelfth lens L12 made of a positive meniscus lens having a convex surface on the magnification side, and a convex surface on the magnification side. A thirteenth lens L13 composed of a negative meniscus lens, a fourteenth lens L14 composed of a biconcave lens, a fifteenth lens L15 composed of a biconvex lens, a sixteenth lens L16 composed of a biconvex lens, and a seventeenth lens L17 composed of a biconvex lens. It consists of and.

  The projection variable magnification optical system of Example 1 is composed of a single lens in which all the lenses are not cemented. Moreover, since all the lens surfaces are spherical and no aspherical surface is used, this is advantageous in terms of cost.

  The upper table of Table 1 shows basic lens data of the projection variable magnification optical system of Example 1. Table 1 also shows the diaphragm 3 and the glass blocks 2a and 2b. In Table 1, in the column of Si, i-th (i = 1) when the surface number is given to the component so that the surface on the enlargement side of the component on the most enlargement side is first and increases sequentially toward the reduction side. 2, 3, ...). The Ri column indicates the radius of curvature of the i-th surface, and the Di column indicates the surface spacing on the optical axis Z between the i-th surface and the i + 1-th surface. Further, in the column of Ndj, the d-line (wavelength 587.6 nm) of the j-th (j = 1, 2, 3,. The νdj column indicates the Abbe number of the j-th component with respect to the d-line.

  However, the sign of the radius of curvature is positive when the surface shape is convex on the enlargement side and negative when the surface shape is convex on the reduction side. The distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the fourth lens group G4 and the fifth lens group G4. The interval of the lens group G5 is a variable interval that changes at the time of zooming, and (variable 1), (variable 2), (variable 3), and (variable 4) are entered in the columns corresponding to these intervals, respectively. Yes.

  The lower table of Table 1 shows the focal length of the entire system at the wide-angle end, the intermediate focal position, and the telephoto end, and the values of the variable intervals (variable 1), (variable 2), (variable 3), and (variable 4). . Further, at the top of Table 1, the F number Fno. Of the projection variable magnification optical system of Example 1 is shown. And a full angle of view 2ω.

  The data in Table 1 are values when the focal length of the entire projection variable magnification optical system at the wide angle end is normalized to 10.0. In Table 1, numerical values rounded by a predetermined digit are shown.

  27A to 27D, respectively, spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration (chromatic aberration of magnification) of the variable power optical system for projection of Example 1 at the wide-angle end. An aberration diagram is shown. 27E to 27H show the spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration (chromatic aberration of magnification) of the projection variable magnification optical system of Example 1 at the intermediate focal position, respectively. Each aberration diagram is shown. FIGS. 27I to 27L respectively show spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration (chromatic aberration of magnification) of the projection variable magnification optical system of Example 1 at the telephoto end. An aberration diagram is shown.

  The aberration diagrams in FIGS. 27A to 27L are based on the d-line, but in the spherical aberration diagram, the F-line (wavelength wavelength 486.1 nm) and the C-line (wavelength 656.3 nm). ) Also shows aberrations, and the lateral chromatic aberration diagram shows aberrations related to the F-line and C-line. In the astigmatism diagram, aberrations in the sagittal direction and the tangential direction are indicated by a solid line and a broken line, respectively. F described above the vertical axis of the spherical aberration diagram indicates the F number, and ω described above the vertical axis of the other aberration diagrams indicates the half angle of view. The aberration diagrams in FIGS. 27A to 27L are obtained when the reduction magnification is −0.002 times.

  The symbols, meanings, and description methods of the lens configuration diagram, lens group arrangement diagram, table, and aberration diagram of Example 1 described above are basically the same for the following Examples 2 to 13 unless otherwise specified. is there. In addition, the lens configuration diagram, the lens group arrangement diagram, and the aberration diagram of Example 1 described above are those when the reduction magnification is −0.002 times, and the basic lens data is standardized with a focal length of 10.0. This also applies to the following Examples 2 to 13.

<Example 2>
FIGS. 3 and 4 show the lens configuration and ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 2, respectively, and the arrangement of the lens groups and ray trajectories at each position during zooming. The projection variable optical system according to Example 2 has substantially the same configuration as the projection variable optical system according to Example 1, but the fifth lens L5 of the first lens group G1 is formed of a biconvex lens. The difference is that the seventh lens L7 of the second lens group G2 is a positive meniscus lens having a convex surface facing the reduction side.

  F-number Fno. Of the variable power optical system for projection of Example 2. The total field angle 2ω is shown at the top of Table 2, the basic lens data is shown in the upper table of Table 2, and the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the value of each variable interval are shown. The results are shown in the lower table of Table 2. FIGS. 28A to 28L show aberration diagrams of the variable power optical system for projection according to the second embodiment.

<Example 3>
FIG. 5 and FIG. 6 show the lens configuration and ray trajectory at the wide angle end of the projection variable magnification optical system of Example 3, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable optical system according to Example 3 has substantially the same configuration as the projection variable optical system according to Example 1, but the fifth lens L5 of the first lens group G1 is a biconvex lens. The difference is that the seventh lens L7 of the second lens group G2 is a positive meniscus lens having a convex surface facing the reduction side.

  F-number Fno. Of the variable power optical system for projection of Example 3. And the total angle of view 2ω are shown at the top of Table 3, the basic lens data is shown in the upper table of Table 3, and the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the value of each variable interval are shown. The results are shown in the lower table of Table 3, respectively. FIGS. 29A to 29L show aberration diagrams of the projection variable magnification optical system of Example 3. FIG.

<Example 4>
FIG. 7 and FIG. 8 show the lens configuration and the ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 4, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable magnification optical system according to Example 4 has substantially the same configuration as the projection variable magnification optical system according to Example 1, but the fifth lens L5 of the first lens group G1 is a biconvex lens. The difference is that the seventh lens L7 of the second lens group G2 is formed of a positive meniscus lens having a convex surface facing the reduction side, and that the diaphragm 3 is located between the twelfth lens L12 and the thirteenth lens L13. Yes.

  F-number Fno. Of the variable power optical system for projection of Example 4. The total field angle 2ω is shown at the top of Table 4, the basic lens data is shown in the upper table of Table 4, the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the values of each variable interval. The results are shown in the lower table of Table 4, respectively. FIGS. 30A to 30L show aberration diagrams of the projection variable magnification optical system of Example 4. FIGS.

<Example 5>
FIG. 9 and FIG. 10 show the lens configuration and ray trajectory at the wide angle end of the projection variable magnification optical system of Example 5, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. In the variable power optical system for projection according to Example 5, the sign of refractive power of each lens group of the first lens group G1 to the fifth lens group G5, the fixed group at the time of zooming, and the moving group are described in Example 1. Although the configuration is the same as that of the projection variable magnification optical system, the lens configuration of each lens unit is different from that of the first embodiment as described below.

  The first lens group G1, in order from the magnifying side, a first lens L1 made of a positive meniscus lens having a convex surface on the magnifying side, a second lens L2 made of a negative meniscus lens having a concave surface on the reducing side, A third lens L3 made of a negative meniscus lens having a concave surface facing the reduction side, a fourth lens L4 made of a biconcave lens, a fifth lens L5 made of a negative meniscus lens having a convex surface facing the enlargement side, and a biconvex lens And a sixth lens L6. The fifth lens L5 and the sixth lens L6 are cemented.

  The second lens group G2 includes a seventh lens L7 made of a biconcave lens. The third lens group G3 includes an eighth lens L8 made of a positive meniscus lens having a convex surface directed toward the reduction side. The fourth lens group G4 includes, in order from the magnifying side, a ninth lens L9 made of a biconvex lens, a tenth lens L10 made of a negative meniscus lens having a convex surface facing the magnifying side, and an eleventh lens L11 made of a biconvex lens. It is composed of

  The fifth lens group G5 has, in order from the magnifying side, a twelfth lens L12 made of a negative meniscus lens having a convex surface directed toward the magnifying side, an aperture (including an aperture and a variable aperture) 3, and a convex surface directed toward the magnifying side. A thirteenth lens L13 made of a positive meniscus lens, a fourteenth lens L14 made of a negative meniscus lens having a convex surface facing the enlargement side, a fifteenth lens L15 made of a biconvex lens, and a sixteenth lens L16 made of a biconcave lens The 17th lens L17 which consists of a biconvex lens, and the 18th lens L18 which consists of a biconvex lens.

  The projection variable magnification optical system of Example 5 is composed of a single lens in which all the lenses on the reduction side of the first lens group G1 are not cemented. Moreover, since all the lens surfaces are spherical and no aspherical surface is used, this is advantageous in terms of cost.

  F-number Fno. Of the variable power optical system for projection of Example 5. And the total angle of view 2ω are shown at the top of Table 5, basic lens data is shown in the upper table of Table 5, the focal length of the entire system at the wide angle end, the intermediate focus position, the telephoto end, and the values of each variable interval. The results are shown in the lower table of Table 5, respectively. FIGS. 31A to 31L show aberration diagrams of the projection variable magnification optical system of Example 5. FIGS.

<Example 6>
FIGS. 11 and 12 show the lens configuration and the ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 6, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable magnification optical system according to Example 6 has substantially the same configuration as the projection variable magnification optical system according to Example 5, but the fifth lens L5 of the first lens group G1 is a biconcave lens. The point is that the eighth lens L8 of the third lens group G3 is a biconvex lens, the tenth lens L10 of the fourth lens group G4 is a biconcave lens, and the twelfth lens L12 of the fifth lens group G5 is a biconcave lens. This is different in that the thirteenth lens L13 of the fifth lens group G5 is composed of a biconvex lens.

  F-number Fno. Of the variable power optical system for projection of Example 6. The total field angle 2ω is shown at the top of Table 6, the basic lens data is shown in the upper table of Table 6, the focal length of the entire system at the wide angle end, the intermediate focus position, the telephoto end, and the values of each variable interval. The results are shown in the lower table of Table 6, respectively. FIGS. 32A to 32L show aberration diagrams of the zooming optical system for projection according to the sixth example.

<Example 7>
FIG. 13 and FIG. 14 show the lens configuration and ray trajectory at the wide angle end of the projection variable magnification optical system of Example 7, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable optical system according to Example 7 has substantially the same configuration as the projection variable optical system according to Example 5, but the fourth lens L4 of the first lens group G1 is flat on the enlargement side. The fifth lens L5 of the first lens group G1 is a biconcave lens, the eighth lens L8 of the third lens group G3 is a biconvex lens, and the fourth lens group G4 is the fourth lens group G4. The tenth lens L10 is formed of a biconcave lens, the twelfth lens L12 of the fifth lens group G5 is formed of a planoconcave lens with the plane facing the enlargement side, and the aperture stop 3 is provided on the reduction side surface of the thirteenth lens L13. Are different.

  F-number Fno. Of the variable power optical system for projection of Example 7. And the total angle of view 2ω are shown at the top of Table 7, the basic lens data is shown in the upper table of Table 7, the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the values of each variable interval. The results are shown in the lower table of Table 7, respectively. 33A to 33L show aberration diagrams of the projection variable magnification optical system of Example 7. FIG.

<Example 8>
FIGS. 15 and 16 show the lens configuration and ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 8, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable optical system according to Example 8 has substantially the same configuration as the projection variable optical system according to Example 5, but the eleventh lens L11 of the fourth lens group G4 is convex on the enlargement side. It is different in that it is composed of a positive meniscus lens facing.

  F-number Fno. Of the variable magnification optical system for projection according to the eighth embodiment. And the total angle of view 2ω are shown at the top of Table 8, the basic lens data is shown in the upper table of Table 8, the focal length of the entire system at the wide angle end, the intermediate focus position, the telephoto end, and the values of each variable interval. The results are shown in the lower table of Table 8, respectively. FIGS. 34A to 34L show aberration diagrams of the variable power optical system for projection according to Example 8. FIG.

<Example 9>
FIGS. 17 and 18 show the lens configuration and the ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 9, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable magnification optical system according to Example 9 has substantially the same configuration as the projection variable magnification optical system according to Example 5, but the fourth lens L4 of the first lens group G1 is flat on the enlargement side. The fifth lens L5 is a biconcave lens, the eighth lens L8 of the third lens group G3 is a biconvex lens, and the tenth lens L10 of the fourth lens group G4 is both The difference is that the lens is made of a concave lens, and the twelfth lens L12 of the fifth lens group G5 is made of a plano-concave lens with the plane facing the magnification side.

  F-number Fno. Of the variable power optical system for projection of Example 9. The total field angle 2ω is shown at the top of Table 9, the basic lens data is shown in the upper table of Table 9, and the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the value of each variable interval are shown. The results are shown in the lower table of Table 9, respectively. FIGS. 35A to 35L are aberration diagrams of the projection variable magnification optical system of Example 9. FIG.

<Example 10>
FIGS. 19 and 20 show the lens configuration and the ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 10, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. In the variable power optical system for projection according to Example 10, the sign of the refractive power of each lens group of the first lens group G1 to the fifth lens group G5, the fixed group at the time of zooming, and the moving group are described in Example 1. Although the configuration is the same as that of the projection variable magnification optical system, the lens configuration of each lens unit is different from that of the first embodiment as described below.

  The first lens group G1 includes, in order from the magnification side, a first lens L1 composed of a biconvex lens, a second lens L2 composed of a negative meniscus lens having a concave surface facing the reduction side, and a negative lens facing the concave surface toward the reduction side. The lens includes a third lens L3 made of a meniscus lens, a fourth lens L4 made of a biconcave lens, a fifth lens L5 made of a biconcave lens, and a sixth lens L6 made of a biconvex lens. The fifth lens L5 and the sixth lens L6 are cemented.

  The second lens group G2 includes a seventh lens L7 made of a biconcave lens. The third lens group G3 includes an eighth lens L8 made of a biconvex lens. The fourth lens group G4 includes, in order from the magnification side, a ninth lens L9 made of a biconvex lens, a tenth lens L10 made of a biconcave lens, and an eleventh lens L11 made of a biconvex lens.

  The fifth lens group G5 includes, in order from the magnifying side, a twelfth lens L12 made of a biconcave lens, a thirteenth lens L13 made of a positive meniscus lens having a convex surface facing the magnifying side, and a reduction-side surface of the thirteenth lens L13. 3 (including an aperture and a variable aperture), a 14th lens L14 made of a biconvex lens, a 15th lens L15 made of a biconcave lens, a 16th lens L16 made of a biconvex lens, and a biconvex lens. The 17th lens L17 and the 18th lens L18 which consists of a plano-convex lens which orient | assigned the plane to the reduction side are comprised.

  The variable power optical system for projection of Example 10 is composed of a single lens in which all the lenses on the reduction side of the first lens group G1 are not cemented. Moreover, since all the lens surfaces are spherical and no aspherical surface is used, this is advantageous in terms of cost.

  F-number Fno. Of the variable power optical system for projection of Example 10. The total angle of view 2ω is shown at the top of Table 10, the basic lens data is shown in the upper table of Table 10, the focal length of the entire system at the wide angle end, the intermediate focus position, the telephoto end, and the value of each variable interval. Each is shown in the lower table of Table 10. FIGS. 36A to 36L show aberration diagrams of the projection variable magnification optical system of Example 10. FIGS.

<Example 11>
FIG. 21 and FIG. 22 show the lens configuration and ray trajectory at the wide angle end of the projection variable magnification optical system of Example 11, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable magnification optical system according to Example 11 has, in order from the enlargement side, a first lens group G1 having a negative refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. The third lens group G3 and a fourth lens group G4 having a positive refractive power are arranged in a four-group configuration, the reduction side is telecentric, and the fourth lens group G4 has a reflective liquid crystal on the reduction side. Glass blocks 2a and 2b such as a light valve image display surface 1 including a display panel and a color synthesis prism (including filters such as an infrared cut filter and a low-pass filter) are disposed.

  At the time of zooming, the first lens group G1 and the fourth lens group G4 are fixed, the second lens group G2 and the third lens group G3 are movable, and the movable mode is shown in FIG. Further, the numerical aperture is set to be constant over the entire range of zooming.

  The first lens group G1 includes, in order from the magnifying side, a first lens L1 made of a plano-convex lens having a convex surface on the magnifying side, a second lens L2 made of a negative meniscus lens having a concave surface on the reducing side, and a biconcave lens. The third lens L3 and the fourth lens L4, a fifth lens L5 made of a negative meniscus lens having a concave surface facing the reduction side, and a sixth lens L6 made of a biconvex lens. The fifth lens L5 and the sixth lens L6 are cemented.

  The second lens group G2 includes, in order from the enlargement side, a seventh lens L7 made of a negative meniscus lens having a convex surface facing the reduction side, and an eighth lens L8 made of a positive meniscus lens having a convex surface facing the reduction side. Has been. The third lens group G3 includes, in order from the enlargement side, a ninth lens L9 made of a positive meniscus lens having a convex surface facing the reduction side, and a tenth lens L10 made of a negative meniscus lens having a convex surface facing the reduction side, It is composed of an eleventh lens L11 made of a biconvex lens.

  The fourth lens group G4 has, in order from the magnifying side, a twelfth lens L12 made of a biconcave lens, a diaphragm (including an aperture and a variable diaphragm) 3, a thirteenth lens L13 made of a biconvex lens, and a concave surface facing the reduction side. A fourteenth lens L14 made of a negative meniscus lens, a fifteenth lens L15 made of a biconvex lens, a sixteenth lens L16 made of a biconcave lens, a seventeenth lens L17 made of a biconvex lens, and an eighteenth lens made of a biconvex lens. L18.

  The variable power optical system for projection in Example 11 is composed of a single lens in which all the lenses on the reduction side of the first lens group G1 are not cemented. Moreover, since all the lens surfaces are spherical and no aspherical surface is used, this is advantageous in terms of cost.

  F-number Fno. Of the variable power optical system for projection of Example 11 And the total angle of view 2ω are shown at the top of Table 11, basic lens data is shown in the upper table of Table 11, and the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the values of each variable interval are shown. Each is shown in the lower table of Table 11. FIGS. 37A to 37L show aberration diagrams of the projection variable magnification optical system of Example 11. FIGS.

<Example 12>
FIG. 23 and FIG. 24 show the lens configuration and ray trajectory at the wide-angle end of the projection variable magnification optical system of Example 12, respectively, the arrangement of the lens groups and the ray trajectory at each position during zooming. The projection variable optical system according to Example 12 has substantially the same configuration as the projection variable optical system according to Example 11, but the first lens L1 of the first lens group G1 is located on the enlargement side. The difference is that the lens is formed of a positive meniscus lens having a convex surface, and the arrangement order of the diaphragm 3 and the twelfth lens L12 is switched and the diaphragm 3 is disposed on the most enlarged side of the fourth lens group G4.

  F-number Fno. Of the variable power optical system for projection of Example 12. And the total field angle 2ω are shown at the top of Table 12, basic lens data is shown in the upper table of Table 12, and the focal length of the entire system at the wide-angle end, the intermediate focal position, the telephoto end, and the value of each variable interval are shown. The results are shown in the lower table of Table 12, respectively. In addition, FIGS. 38A to 38L show aberration diagrams of the projection variable magnification optical system of Example 12, respectively.

<Example 13>
FIGS. 25 and 26 show the lens configuration and light ray locus at the wide angle end of the projection variable magnification optical system of Example 13, respectively, the arrangement of the lens groups and the light ray locus at each position during magnification. The variable power optical system for projection according to Example 13 has substantially the same configuration as the variable power optical system for projection according to Example 11, but the first lens L1 of the first lens group G1 is more than a biconvex lens. Is different.

  F-number Fno. Of the variable power optical system for projection of Example 13 And the total field angle 2ω are shown at the top of Table 13, basic lens data is shown in the upper table of Table 13, and the focal length of the entire system at the wide angle end, the intermediate focal position, the telephoto end, and the values of the variable intervals are shown. The results are shown in the lower table of Table 13, respectively. FIGS. 39A to 39L show aberration diagrams of the projection variable magnification optical system of Example 13. FIGS.

  Table 14 shows values related to the values corresponding to the conditional expressions (1) to (8) of Examples 1 to 13. The sign of exP is negative when the paraxial exit pupil position is on the enlargement side with respect to the reduction-side image plane, and is positive when the paraxial exit pupil position is on the reduction side. As shown in Table 14, the projection variable magnification optical systems of Examples 1 to 13 satisfy all the conditional expressions (1) to (8).

  In Examples 1 to 13 described above, the reduction side is telecentric, has a long back focus, does not employ an aspheric surface, and has an F number of about 2.5 over the entire zoom range from the wide-angle end to the telephoto end. Although the zoom ratio is small and the zoom ratio is as large as 1.52 to 1.75, fluctuations in aberrations during zooming are suppressed, and each optical aberration is well corrected to achieve high optical performance. It is what you have.

<Modification of Example 1>
The first embodiment is configured to be a zoom lens by changing only the distance between the lens groups. Table 15 shows the focal length of the entire system at the wide-angle end, the intermediate focal position, and the telephoto end when the projection distance is infinite when using Example 1 as a zoom lens by changing only the distance between the lens groups in Table 15. The distance of each variable interval is shown. When the modified example of the first embodiment is used as a zoom lens, inner focusing is performed by moving the fifth lens L5 closest to the reduction side of the first lens group G1 in the optical axis direction when the projection distance varies. The focus method is adopted. In Table 15, the surface interval that changes during the focusing, that is, the interval between the fourth lens L4 and the fifth lens L5 is shown as D8.

<Modification of Example 11>
The eleventh embodiment is also configured to be a zoom lens by changing only the distance between the lens groups. Table 16 shows the focal length of the entire system at the wide-angle end, the intermediate focal position, and the telephoto end when the projection distance is infinite when using Example 11 as a zoom lens by changing only the distance between the lens groups in Table 16. The distance of each variable interval is shown. When the modified example of Example 11 is used as a zoom lens, focusing when the projection distance changes is performed by moving the fifth lens L5 and the sixth lens L6 of the first lens group G1 in the optical axis direction. We adopt inner focus method to perform. In Table 16, the surface interval that changes during the focusing, that is, the interval between the fourth lens L4 and the fifth lens L5 is shown as D8.

  As described above, the present invention has been described with reference to the embodiments and examples. However, the projection variable magnification optical system according to the present invention is not limited to the above examples, and various modifications can be made. For example, the radius of curvature, the surface interval, the refractive index, and the Abbe number of each lens can be appropriately changed.

  Further, the projection display device of the present invention is not limited to the above configuration, and for example, the light valve used and the optical member used for light beam separation or light beam synthesis are not limited to the above configuration, Various modifications can be made.

DESCRIPTION OF SYMBOLS 1 Image display surface 2a, 2b Glass block 3 Aperture 10, 20 Illumination optical system 11a-11c, 21a-21c Reflective display element 12, 13 Dichroic mirror 14 Cross dichroic prism 15a-15c, 25 Polarization separation prism 18 Total reflection mirror 19 , 29 Variable magnification optical system for projection 24a to 24c TIR prism G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group Z Optical axis

Claims (11)

A first lens unit having a negative refractive power arranged at the most enlargement side and fixed at the time of zooming, and a positive refractive power arranged at the most reduction side and fixed at the time of zooming It is substantially composed of a final lens group and a plurality of lens groups that are arranged between the first lens group and the final lens group and move during zooming,
Among the plurality of lens groups that move during zooming, the most magnified lens group has a negative refractive power,
The reduction side is telecentric,
A diaphragm is disposed in the final lens group, and the numerical aperture is set to be constant over the entire range of zooming,
A projection variable magnification optical system satisfying the following conditional expressions (1) to (3):
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
However,
L: Distance on the optical axis from the most enlarged lens surface to the most reduced lens surface at an infinite projection distance Imφ: Maximum effective image circle diameter on the reduction side Bf: Back on the reduction side of the entire system at the wide angle end Focus (Air equivalent distance)
Zr: zoom ratio of the telephoto end with respect to the wide-angle end f: focal length of the entire system at the wide-angle end A first lens unit having a negative refractive power arranged at the most enlargement side and fixed at the time of zooming, and a positive refractive power arranged at the most reduction side and fixed at the time of zooming It is substantially composed of a final lens group and a plurality of lens groups that are arranged between the first lens group and the final lens group and move during zooming,
The reduction side is telecentric,
A diaphragm is disposed in the final lens group, and the numerical aperture is set to be constant over the entire range of zooming,
A projection variable magnification optical system characterized by satisfying the following conditional expressions (1) to (3) and (6):
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
-10.0 <f1 / f <-2.0 (6)
However,
L: Distance on the optical axis from the most enlarged lens surface to the most reduced lens surface at an infinite projection distance Imφ: Maximum effective image circle diameter on the reduction side Bf: Back on the reduction side of the entire system at the wide angle end Focus (Air equivalent distance)
Zr: zoom ratio of the telephoto end with respect to the wide-angle end f: focal length of the entire system at the wide-angle end
f1: Focal length of the first lens group A first lens unit having a negative refractive power arranged at the most enlargement side and fixed at the time of zooming, and a positive refractive power arranged at the most reduction side and fixed at the time of zooming It is substantially composed of a final lens group and a plurality of lens groups that are arranged between the first lens group and the final lens group and move during zooming,
The reduction side is telecentric,
A diaphragm is disposed in the final lens group, and the numerical aperture is set to be constant over the entire range of zooming,
A projection variable magnification optical system characterized by satisfying the following conditional expressions (1) to (3) and (8):
L / Imφ <11.5 (1)
4.5 <(Bf × Zr ² ) / Imφ (2)
0.54 <(Imφ × Bf × Zr ² ) / (f × L) (3)
1.4 <Zr (8)
However,
L: Distance on the optical axis from the most enlarged lens surface to the most reduced lens surface at an infinite projection distance Imφ: Maximum effective image circle diameter on the reduction side Bf: Back on the reduction side of the entire system at the wide angle end Focus (Air equivalent distance)
Zr: zoom ratio of the telephoto end with respect to the wide-angle end f: focal length of the entire system at the wide-angle end The following conditional expression (4) according to claim 1-3 variable magnification optical system for projection according to any one of the which is characterized by satisfying the.
enP / f + f / Bf <3.7 (4)
However,
enP: Distance on the optical axis from the most magnified lens surface to the entrance pupil position at the wide angle end when the projection distance is infinite when the magnification side is the entrance side A plurality of lens groups which move during the zooming, substantially for projection magnification optics any one of claims 1-4, characterized in that a lens group of the second group or the third group system. The following conditional expression (5) variable magnification optical system for projection of any one of claims 1-5, characterized by satisfying the.
1.8 <Bf / Imφ (5) The variable power optical system for projection according to claim 1, wherein the following conditional expression (7) is satisfied.
30 <| exP | / Imφ (7)
However,
exP: Distance on the optical axis from the image plane on the reduction side to the paraxial exit pupil position at the wide angle end when the projection distance is infinity when the reduction side is the exit side The variable power optical system for projection according to any one of claims 1 to 7, wherein all lenses on the reduction side of the first lens group are single lenses .   9. The projection variable magnification optical system according to claim 1, wherein the projection variable power optical system is configured to be a zoom lens by changing only an interval between lens groups. 10.   When the projection variable magnification optical system is a zoom lens, focusing is an inner that moves only a part of the first lens group including the lens arranged closest to the reduction side of the first lens group in the optical axis direction. The variable power optical system for projection according to any one of claims 1 to 9, wherein the projection variable power optical system is configured to perform the focus method. Light source, a light valve on which light is incident from the light source, any one of claims 1-10 as a variable magnification optical system for projection that projects the optical image formed by the light modulated light by the light valve onto a screen A projection display device comprising the projection variable magnification optical system according to claim 1.