JP2020077008A - Projection optical system and projector - Google Patents

Abstract

To provide a projection optical system corrected excellently in off-axis aberrations despite a wide angle of view, and high performance, small in size, and low in cost, and a projector having the same.SOLUTION: A projection optical system LN is capable of performing an enlarged projection of an image displayed on an image display surface IM2 by more than a half view angle 40°, and includes: first and second optical systems LN1, LN2 in order from an enlargement side, forms an intermediate image IM1 by the second optical system LN2, enlarges and projects the intermediate image IM1 by the first optical system LN1, and satisfies a conditional expression : 1<Ff/|Fw|<2,0.4<Lf/Lw<0.6 (Ff: a focal length of the first optical system, Fw: a focal length of the whole system (the focal length of the whole system at the maximum viewing angle when the projection optical system is a zoom lens), Lf: a distance on the optical axis from the maximum enlarged side surface vertex of the first optical system to the intermediate image, and Lw: a total length of the lens (the total length of the lens at the maximum viewing angle when the projection optical system is a zoom lens)).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection optical system and a projector, and for example, enlarges and projects a display image of an image display element such as a digital micromirror device (LCD) or a liquid crystal display (LCD) on a screen with a wide angle of view. The present invention relates to a projection optical system suitable for this and a projector equipped with the projection optical system.

  In recent years, there has been a demand for a projection optical system having a wide angle of view that enables large-screen projection even in a narrow place. In order to achieve both a wide angle of view and excellent aberration performance, it is effective to use a relay lens, and a projection optical system using the relay lens is proposed in Patent Documents 1 and 2 for the wide angle projection. Has been done.

JP, 2005-060062, A JP, 2005-128286, A

  Even when a relay lens is used, it is difficult to correct off-axis aberrations, especially distortion. Therefore, it is necessary to use an aspherical lens in the enlargement side portion having a large lens diameter, which causes a high cost. For example, in the zoom lens described in Patent Document 1, the off-axis aberration is corrected well, but the aspherical surface is used as the second lens from the enlargement side in the enlargement side portion with a large diameter, so the cost is low. It is high. The zoom lens described in Patent Document 2 does not use an aspherical surface on the magnifying side, but has large off-axis aberrations, particularly distortion, and cannot be used as a projection optical system.

  The present invention has been made in view of such a situation, and an object thereof is a high-performance, small-sized and low-cost projection optical system in which an off-axis aberration is well corrected while having a wide angle of view, and It is to provide a projector equipped with.

In order to achieve the above object, the projection optical system of the first invention is a projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more,
A first optical system and a second optical system in order from the enlargement side, the second optical system forms an intermediate image of the image, and the first optical system enlarges and projects the intermediate image;
It is characterized in that the following conditional expressions (1) and (2) are satisfied.
1 <Ff / | Fw | <2 (1)
0.4 <Lf / Lw <0.6 (2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.

  A projection optical system according to a second invention is characterized in that, in the first invention, the three lenses from the most magnifying side of the first optical system do not include an aspherical surface.

  A projection optical system according to a third invention is characterized in that, in the first or second invention, the first optical system does not include an aspherical surface.

  A projection optical system according to a fourth invention is characterized in that, in any one of the above-mentioned first to third inventions, it does not include an aspherical surface.

A projection optical system according to a fifth aspect of the invention is characterized in that, in any one of the first to fourth aspects of the invention, the following conditional expression (3) is satisfied.
0.8 <(Y ′ / Y) × β2 <1 (3)
However,
Y ': principal ray height from the optical axis at the intermediate image position of the most off-axis ray at the maximum angle of view,
Y: Maximum image height on the image display surface,
β2: paraxial magnification of the second optical system at the maximum angle of view (here, the paraxial magnification is [image size on image display surface] / [intermediate image size]),
Is.

  A projection optical system according to a sixth aspect of the invention is characterized in that, in any one of the first to fifth aspects of the invention, the lens on the most magnifying side of the first optical system is a negative lens.

  A projection optical system according to a seventh invention is characterized in that, in the invention according to any one of the first to sixth inventions, it has at least one positive lens within three lenses from the most enlarged side of the first optical system. To do.

  The projection optical system according to an eighth invention is the projection optical system according to any one of the first to seventh inventions, wherein the first optical system has a negative lens, a negative lens, a positive lens, and a negative lens in order from the enlargement side. Is characterized by.

  A projection optical system according to a ninth invention is the projection optical system according to any one of the first to eighth inventions, wherein a lens group including a part of at least one of the first and second optical systems is provided along an optical axis. It is characterized in that the magnification is changed by moving it.

  A projection optical system according to a tenth invention is characterized in that, in the ninth invention, only the second optical system has a lens group that moves for the magnification change.

  A projector according to an eleventh aspect of the invention is an image display element having the image display surface, and the projection according to any one of the first to tenth aspects of the invention, which enlarges and projects an image displayed on the image display surface onto a screen surface. And an optical system.

  According to the present invention, since the intermediate image is formed by the second optical system and the focal length and the intermediate image position of the first optical system are properly set, even if the angle of view is wide. It is possible to excellently correct off-axis aberrations such as distortion without using an aspherical surface. Therefore, it is possible to realize a high-performance, small-sized, low-cost projection optical system in which the off-axis aberration is well corrected while having a wide angle of view, and a projector including the projection optical system.

FIG. 3 is an optical configuration diagram of the first embodiment (Example 1). The optical block diagram of 2nd Embodiment (Example 2). The optical block diagram of 3rd Embodiment (Example 3). The optical block diagram of 4th Embodiment (Example 4). The optical block diagram of 5th Embodiment (Example 5). 6 is an aberration diagram of Example 1. FIG. FIG. 6 is an aberration diagram of Example 2. FIG. 9 is an aberration diagram of Example 3. 16 is an aberration diagram of Example 4. FIG. 16 is an aberration diagram for Example 5. FIG. FIG. 3 is a schematic diagram showing an embodiment of a projector.

Hereinafter, the projection optical system, the projector, and the like according to the embodiments of the present invention will be described. A projection optical system according to an embodiment of the present invention is a projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more, and the first optical system in order from the magnifying side. System and a second optical system, the second optical system forms an intermediate image of the image, the first optical system magnifies and projects the intermediate image, and the following conditional expressions (1) and (2) are satisfied. The composition is satisfied.
1 <Ff / | Fw | <2 (1)
0.4 <Lf / Lw <0.6 (2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.

  As a lens system that constitutes the projection optical system, in addition to a single focus lens, a lens system with a variable focal length such as a zoom lens can be used. The "enlargement side" is the direction in which the optical image is enlarged and projected onto the screen surface, and the opposite direction is the "reduction side", that is, the image display element that displays the original optical image (that is, the reduction-side image surface). The direction in which the (eg, digital micromirror device) is placed.

  Conditional expression (1) defines the refractive power of the first optical system that magnifies and projects the intermediate image in the wide-angle projection optical system having the second optical system that is the relay lens. If the upper limit of conditional expression (1) is exceeded, the focal length of the first optical system becomes too long, so it is necessary to make the intermediate image large in order to achieve a wide angle of view, and the lens diameter near the intermediate image is large. Become. Further, in order to widen the angle of view in the state where the focal length of the first optical system is long, it is necessary to shorten the focal length of the second optical system, and for that purpose, the negative image on the intermediate image side of the second optical system is required. It is necessary to increase the refractive power. In that case, a negative distortion is generated in the second optical system, so that the negative distortion generated in the first optical system for magnifying and projecting is amplified, and it becomes difficult to suppress the distortion aberration in the entire system. When the value goes below the lower limit of the conditional expression (1), it becomes difficult to correct off-axis aberration generated in the first optical system, particularly distortion. Therefore, by satisfying the conditional expression (1), it becomes possible to effectively suppress the off-axis aberration such as the distortion while achieving the downsizing of the lens diameter.

  Conditional expression (2) defines the total length of the first optical system that magnifies and projects the intermediate image in the wide-angle projection optical system having the second optical system that is the relay lens. If the upper limit of conditional expression (2) is exceeded, the total length of the first optical system becomes too long, and the number of lenses of the first optical system that tend to have a large diameter due to magnified projection increases, leading to higher costs. Moreover, since the total length of the second optical system is smaller than that of the first optical system, the number of lenses of the second optical system becomes insufficient, and the aberration in the intermediate image, especially the field curvature becomes large, which is good for the entire system. It becomes difficult to obtain aberration performance. When the value goes below the lower limit of the conditional expression (2), the number of lenses for achieving a wide angle of view becomes insufficient, and the refractive power of each lens becomes large, so that it becomes difficult to correct the off-axis aberration. Therefore, by satisfying this conditional expression (2), it becomes possible to effectively suppress off-axis aberrations such as field curvature while achieving reduction in the total length.

  Generally, an aspherical glass lens having a large diameter is technically difficult to manufacture, which causes a cost increase, and an aspherical plastic lens having a large diameter causes a shape change due to temperature to cause a performance deterioration. Therefore, the aspherical surface is unsuitable for a projector lens having a large diameter and a high temperature, and it can be said that it is preferable that the projection optical system does not include the aspherical surface. Then, it is the condition setting defined by the conditional expressions (1) and (2) that enables the projection optical system to have high performance and a wide angle of view without using an aspherical surface.

  In the projection optical system having the above characteristic structure, the second optical system forms an intermediate image, and the focal length and the intermediate image position of the first optical system are appropriately set. Even at an angle, off-axis aberrations such as distortion can be satisfactorily corrected without using an aspherical surface. Therefore, it is possible to realize a high-performance, small-sized, low-cost projection optical system in which the off-axis aberration is well corrected while having a wide angle of view. If the projection optical system is used in a projector, it can contribute to high performance, high functionality, compact size, etc. of the projector. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance and size reduction will be described below.

It is more desirable to satisfy the following conditional expression (1a).
1.3 <Ff / | Fw | <1.7 (1a)
The conditional expression (1a) defines a more preferable conditional range based on the above viewpoints and the like among the conditional ranges defined by the conditional expression (1). Therefore, preferably, by satisfying the conditional expression (1a), the above effect can be further enhanced.

It is more desirable to satisfy the following conditional expression (2a).
0.4 <Lf / Lw <0.5 (2a)
The conditional expression (2a) defines a more preferable conditional range based on the above viewpoints and the like among the conditional ranges defined by the conditional expression (2). Therefore, preferably, by satisfying the conditional expression (2a), the above effect can be further enhanced.

  In the projection optical system, it is desirable that the three lenses from the most magnifying side of the first optical system do not include an aspherical surface. According to this configuration, it is possible to achieve the same distortion performance without using an aspherical surface for the purpose of correcting the distortion, and reduce the manufacturing cost of the first optical system magnifying lens, which tends to have a large diameter, and further increase the cost. Down is possible.

  It is desirable that the projection optical system does not include an aspherical surface in the first optical system. With this configuration, it is possible to reduce the manufacturing cost of the entire first optical system, which tends to have a large diameter, while achieving the same aberration performance without using an aspherical surface for the purpose of correcting field curvature and spherical aberration. Therefore, the cost can be further reduced.

  It is desirable that the projection optical system does not include an aspherical surface. With this configuration, it is possible to reduce the manufacturing cost of the entire projection optical system while achieving the same aberration performance without using an aspherical surface for the purpose of correcting aberrations in the intermediate image, and it is possible to further reduce costs. ..

It is desirable to satisfy the following conditional expression (3).
0.8 <(Y ′ / Y) × β2 <1 (3)
However,
Y ': principal ray height from the optical axis at the intermediate image position of the most off-axis ray at the maximum angle of view,
Y: Maximum image height on the image display surface,
β2: paraxial magnification of the second optical system at the maximum angle of view (here, the paraxial magnification is [image size on image display surface] / [intermediate image size]),
Is.

  Conditional expression (3) defines the ratio between the maximum real image height (Y ′) of the intermediate image and the maximum paraxial image height (Y / β2), that is, the amount of distortion of the second optical system. When the value goes below the lower limit of the conditional expression (3), the distortion on the plus side generated in the second optical system is too large, and the actual intermediate image becomes too small. Since the refracting power of the first optical system becomes large in order to magnify and project it, it becomes difficult to suppress the off-axis aberration generated in the first optical system. If the upper limit of conditional expression (3) is exceeded, negative distortion occurs in the second optical system, so negative distortion that occurs in the magnified first optical system is amplified, making it difficult to suppress distortion. Become. Therefore, by satisfying this conditional expression (3), it becomes possible to suppress off-axis aberrations such as distortion aberration in a well-balanced manner.

It is more desirable to satisfy the following conditional expression (3a).
0.9 <(Y ′ / Y) × β2 <1 (3a)
The conditional expression (3a) defines a more preferable conditional range based on the above viewpoints among the conditional range defined by the conditional expression (3). Therefore, preferably, by satisfying the conditional expression (3a), the above effect can be further enhanced.

  It is preferable that the most magnifying lens of the first optical system is a negative lens. With this configuration, the diameter of the lens on the most magnifying side, which has the largest diameter, can be reduced, and the cost can be further reduced.

  It is desirable to have at least one positive lens within three lenses from the most enlarged side of the first optical system. According to this configuration, the negative distortion that occurs in the first optical system can be canceled by using a lens close to the magnification side, which is effective for distortion correction, as a positive lens, so that even better off-axis performance can be obtained. It becomes possible to obtain.

  It is desirable that the first optical system has a negative lens, a negative lens, a positive lens, and a negative lens in this order from the enlargement side. According to this negative-negative-positive-negative refractive power arrangement, it becomes possible to suppress the distortion aberration more effectively while reducing the lens diameter on the maximum magnification side.

  It is desirable to perform zooming by moving a lens group that is a part of at least one of the first and second optical systems along the optical axis. With this configuration, it is possible to perform large-screen projection with good performance even when there are restrictions on the size and installation location.

  It is preferable that only the second optical system has a lens unit that moves for the magnification change. With this configuration, the first optical system that is apt to generate off-axis aberrations can be fixed during zooming, and the occurrence of off-axis aberrations during zooming can be further reduced.

  Next, the specific optical configuration of the projection optical system LN will be described with reference to the first to fifth embodiments. 1 to 4 are optical configuration diagrams respectively corresponding to the projection optical system LN that configures the first to fourth embodiments, and show the lens cross-sectional shape, lens arrangement, etc. of the projection optical system LN that is a zoom lens. , The wide-angle end (W) and the telephoto end (T) are shown in optical cross sections. FIG. 5 is an optical configuration diagram corresponding to the projection optical system LN that constitutes the fifth embodiment, and shows the lens cross-sectional shape, lens arrangement, etc. of the projection optical system LN that is a single focus lens in an optical cross section. . A prism PR (for example, a TIR (Total Internal Reflection) prism, a color separation / combination prism, etc.) and a cover glass CG of the image display element are located on the reduction side of the projection optical system LN.

  The projection optical system LN of the first to fifth embodiments includes a first optical system LN1 (from the first surface to the front of the intermediate image plane IM1) and a second optical system LN2 (the intermediate image plane) in order from the enlargement side. (After IM1 to the final lens surface), the second optical system LN2 forms an intermediate image IM1 of the image (reduction side image surface) displayed on the image display surface IM2 of the image display element, and the intermediate image IM1 Is configured so that the first optical system LN1 magnifies and projects. Among them, the projection optical system LN of the first to fourth embodiments has a positive, positive, positive, positive five-group zoom configuration in which the first optical system LN1 is the first lens group Gr1. Arrows m1, m2, m3, m4, and m5 in FIG. 4 indicate the first lens group Gr1, the second lens group Gr2, the third lens group Gr3, and the third lens group Gr3 during zooming from the wide-angle end (W) to the telephoto end (T). The movement or the fixation of the fourth lens group Gr4 and the fifth lens group Gr5 are each schematically shown. As described above, in the first to fourth embodiments, the projection optical system LN relatively moves the moving group with respect to the image display surface IM2 to change the distance between the groups on the axis to change the wide-angle end ( It is configured to perform zooming (that is, zooming) from W) to the telephoto end (T). In addition, in the first to fourth embodiments, the zoom positions of the prism PR and the cover glass CG located on the reduction side of the fifth lens group Gr5 are also fixed.

  In the first to third embodiments, the first lens group Gr1 and the fifth lens group Gr5 are fixed groups, and the second lens group Gr2, the third lens group Gr3, and the fourth lens group Gr4 are movable groups. , The second lens group Gr2, the third lens group Gr3, and the fourth lens group Gr4 are moved along the optical axis AX to perform zooming. In the fourth embodiment, the first lens group Gr1, the second lens group Gr2, and the fifth lens group Gr5 are fixed groups, and the third lens group Gr3 and the fourth lens group Gr4 are movable groups. The zoom lens is configured to move by moving the lens group Gr3 and the fourth lens group Gr4 along the optical axis AX (substantially, a four-group zoom configuration). In both cases, since the zoom positions of the first lens group Gr1 and the fifth lens group Gr5 are fixed, it is possible to suppress a change in the overall length of the optical system due to zooming, and to reduce zooming because moving parts are reduced. The mechanism can be simplified. The projection optical system LN of each embodiment will be described in more detail below.

  In the first embodiment (FIG. 1), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of, in order from the enlargement side, a positive, positive, and positive second lens group Gr2 to a fifth lens group Gr5. The scaling is performed only in the system LN2. At the time of zooming, the first lens group Gr1 and the fifth lens group Gr5 are fixed, and when zooming from the wide-angle end (W) to the telephoto end (T), the second lens group Gr2 has a convex locus on the enlargement side. The third lens group Gr3 and the fourth lens group Gr4 each move monotonically to the enlargement side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

  The intermediate image IM1 formed by the second optical system LN2 is an enlarged image of the image display surface IM2. This makes it possible to reduce the refractive power of the first optical system LN1 and realizes high optical performance without an aspherical surface. In the first optical system LN1, in order from the magnification side, a negative meniscus lens convex to the magnification side, a negative meniscus lens convex to the magnification side, a positive meniscus lens convex to the magnification side, and a negative meniscus lens convex to the magnification side And are arranged, which makes it possible to effectively suppress distortion even without aspherical surfaces. Therefore, it is possible to realize a high-performance wide-angle projection zoom lens at low cost.

  In the second embodiment (FIG. 2), a total of 29 lens components are provided, 16 magnifying sides are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 magnifying sides. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of, in order from the enlargement side, a positive, positive, and positive second lens group Gr2 to a fifth lens group Gr5. The scaling is performed only in the system LN2. At the time of zooming, the first lens group Gr1 and the fifth lens group Gr5 are fixed, and when zooming from the wide-angle end (W) to the telephoto end (T), the second lens group Gr2 has a convex locus on the enlargement side. The third lens group Gr3 and the fourth lens group Gr4 each move monotonically to the enlargement side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

  The intermediate image IM1 formed by the second optical system LN2 is an enlarged image of the image display surface IM2. This makes it possible to reduce the refractive power of the first optical system LN1 and realizes high optical performance without an aspherical surface. The first optical system LN1 includes, in order from the magnification side, a negative meniscus lens convex on the magnification side, a positive meniscus lens convex on the magnification side, and a negative meniscus lens convex on the magnification side. Even without an aspherical surface, it is possible to effectively suppress distortion. Therefore, it is possible to realize a high-performance wide-angle projection zoom lens at low cost.

  In the third embodiment (FIG. 3), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of positive, positive, and positive second lens groups Gr2 to Gr5 in order from the enlargement side. The scaling is performed only in the system LN2. At the time of zooming, the first lens group Gr1 and the fifth lens group Gr5 are fixed, and when zooming from the wide-angle end (W) to the telephoto end (T), the second lens group Gr2 has a convex locus on the enlargement side. The third lens group Gr3 and the fourth lens group Gr4 each move monotonically to the enlargement side. The fourth lens group Gr4 has an aperture stop ST on the most enlargement side.

  The intermediate image IM1 formed by the second optical system LN2 is an enlarged image of the image display surface IM2. This makes it possible to reduce the refractive power of the first optical system LN1 and realizes high optical performance without an aspherical surface. In the first optical system LN1, a negative meniscus lens convex on the magnification side, a positive meniscus lens convex on the magnification side, and a negative meniscus lens convex on the magnification side are arranged in this order from the magnification side. Even without an aspherical surface, it is possible to effectively suppress distortion. Therefore, it is possible to realize a high-performance wide-angle projection zoom lens at low cost.

  In the fourth embodiment (FIG. 4), a total of 30 lens components are provided, 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of, in order from the enlargement side, a positive, positive, and positive second lens group Gr2 to a fifth lens group Gr5. The scaling is performed only in the system LN2. During zooming, the first lens group Gr1, the second lens group Gr2, and the fifth lens group Gr5 are fixed, and when zooming from the wide-angle end (W) to the telephoto end (T), the third lens group Gr3 and The fourth lens group Gr4 group monotonously moves to the enlargement side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

  The intermediate image IM1 formed by the second optical system LN2 is an enlarged image of the image display surface IM2. This makes it possible to reduce the refractive power of the first optical system LN1 and realizes high optical performance without an aspherical surface. In the first optical system LN1, in order from the magnification side, a negative meniscus lens convex on the magnification side, a negative meniscus lens convex on the magnification side, a positive meniscus lens convex on the magnification side, and a negative meniscus lens convex on the magnification side. And are arranged, which makes it possible to effectively suppress distortion even without aspherical surfaces. Therefore, it is possible to realize a high-performance wide-angle projection zoom lens at low cost.

  In the fifth embodiment (FIG. 5), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 and the second optical system LN2 form a positive single focus lens as a whole. The second optical system LN2 has an aperture stop ST near the reduction side of the largest air gap.

  The intermediate image IM1 formed by the second optical system LN2 is an enlarged image of the image display surface IM2. This makes it possible to reduce the refractive power of the first optical system LN1 and realizes high optical performance without an aspherical surface. In the first optical system LN1, in order from the magnification side, a negative meniscus lens convex to the magnification side, a negative meniscus lens convex to the magnification side, a positive meniscus lens convex to the magnification side, and a negative meniscus lens convex to the magnification side And are arranged, which makes it possible to effectively suppress distortion even without aspherical surfaces. Therefore, a low-cost and high-performance wide-angle projection optical system can be realized.

  Next, an embodiment of a projector including the projection optical system LN will be described. FIG. 11 shows a schematic configuration example of the projector PJ. The projector PJ includes a light source 1, an illumination optical system 2, a reflection mirror 3, a prism PR, an image display element (image forming element) 4, a controller 5, an actuator 6, a projection optical system LN, and the like. The control unit 5 is a unit that controls the overall control of the projector PJ. The image display element 4 is an image modulation element (for example, a digital micromirror device) that modulates light to generate an image, has an image display surface IM2 that displays an image, and the image display surface IM2. A cover glass CG is provided on the top.

  Light emitted from the light source 1 (for example, a white light source such as a xenon lamp or a laser light source) is guided to the image display element 4 by the illumination optical system 2, the reflection mirror 3, and the prism PR, and the image display element 4 converts the image light. It is formed. The prism PR is, for example, a TIR prism (a color separation / combination prism or the like) and separates illumination light and projection light. The image light formed by the image display element 4 is enlarged and projected by the projection optical system LN toward the screen surface SC. That is, the image IM2 displayed on the image display element 4 becomes an intermediate image IM1 by the second optical system LN2, and then is enlarged and projected on the screen surface SC by the first optical system LN1.

  As described above, the projector PJ displays the image on the image display element 4, the image display element 4 that displays an image, the light source 1, the illumination optical system 2 that guides the light from the light source 1 to the image display element 4, and the image display element 4. The projection optical system LN for enlarging and projecting an image on the screen surface SC is provided, but the projector to which the projection optical system LN is applicable is not limited to this. For example, if an image display element that displays an image by light emission of the image display surface IM2 itself is used, it is possible to eliminate the need for illumination. In that case, the projector is configured without using the light source 1 or the illumination optical system 2. It is possible.

  In the projection optical system LN, the lens groups that move for zooming and focusing are connected to actuators 6 that move to the enlargement side or the reduction side along the optical axis AX, respectively. A control unit 5 for controlling the movement of the moving group is connected to the actuator 6. It should be noted that the control unit 5 and the actuator 6 may be manually moved without using them.

  Hereinafter, the configuration and the like of the projection optical system embodying the present invention will be described more specifically with reference to the construction data and the like of the examples. Examples 1 to 5 (EX1 to 5) given here are numerical examples corresponding to the above-described first to fifth embodiments, respectively, and are optical configuration diagrams showing the first to fifth embodiments. (FIGS. 1 to 5) respectively show lens cross-sectional shapes, lens arrangements, etc. of corresponding Examples 1 to 5.

  In the construction data of each example, as the surface data, the surface number i, the radius of curvature r (mm), the axial upper surface distance d (mm), the refractive index nd with respect to the d line (wavelength 587.56 nm), in order from the left column, And the Abbe number vd for the d-line. Note that SC is a screen surface, ST is an aperture stop, IM1 is an intermediate image surface, and IM2 is an image display surface.

  As various data of Examples 1 to 4, zoom ratios (zoom ratios, zoom ratios) are shown, and the focal length of the entire system (focal length states W (Wide), M (Middle), and T (Tele)) is shown. Fl, mm), F number (Fno.), Half angle of view (ω, °), image height (ymax, mm), total lens length (TL, mm), back focus (BF, mm), and variable surface spacing ( di, i: surface number, mm) and the focal length (mm) of each lens group as zoom lens group data. Further, as various data of Example 5, the focal length (Fl, mm) of the entire system, F number (Fno.), Half angle of view (ω, °), image height (ymax, mm), total lens length (TL, mm), the back focus (BF, mm), and the focal lengths (Ff, Fr; mm) of the first and second optical systems LN1 and LN2. However, in the back focus BF, the distance from the final lens surface to the paraxial image plane is expressed by the air-converted length, and the total lens length TL is the distance from the frontmost lens surface to the final lens surface plus the back focus BF. It is a thing. The image height ymax corresponds to half the diagonal length of the image display surface IM2.

  Table 1 shows the values corresponding to the conditional expressions and their related data for each example. The conditional expression-related data includes, for example, the maximum half angle of view (ωmax, °), the focal length (Ff, mm) of the first optical system LN1, the focal length (Fr, mm) of the second optical system LN2, and the focus of the entire system. Distance (Fw, mm), distance (Lf, mm) on the optical axis AX from the most enlarged side surface vertex of the first optical system LN1 to the intermediate image IM1, lens total length (Lw, mm), maximum angle of view ωmax The chief ray height (Y ′, mm) from the optical axis AX at the position of the intermediate image IM1 of the off-axis ray, the maximum image height (Y: ymax, mm) on the image display surface IM2, and the second at the maximum angle of view ωmax. It is a paraxial magnification (β2) of the optical system LN2.

  6 to 9 are aberration diagrams (longitudinal aberration diagrams in the infinity in-focus state) corresponding to Examples 1 to 4 (EX1 to EX4), respectively, and (A) to (C) are wide-angle ends. W, (D) to (F) show the intermediate focal length state M, and (G) to (I) show various aberrations at the telephoto end T, respectively. 6 to 9, (A), (D) and (G) are spherical aberration diagrams, (B), (E) and (H) are astigmatism diagrams, and (C), (F), (I) is a distortion diagram. FIG. 10 is an aberration diagram (longitudinal aberration diagram in infinity focused state) corresponding to Example 5 (EX5), in which (A) is a spherical aberration diagram, (B) is an astigmatism diagram, and (C) is a diagram. Is a distortion diagram.

  The spherical aberration diagram shows the spherical aberration amount for the d line (wavelength 587.56 nm) indicated by the solid line, the spherical aberration amount for the C line (wavelength 656.28 nm) indicated by the alternate long and short dash line, and the g line (wavelength 435.84 nm) indicated by the broken line. The amount of spherical aberration is expressed by the amount of deviation (unit: mm) in the optical axis AX direction from the paraxial image plane, and the vertical axis represents the value obtained by normalizing the entrance height to the pupil by its maximum height (that is, Relative pupil height). In the astigmatism diagram, the broken line T represents the tangential image plane with respect to the d-line, and the solid line S represents the sagittal image plane with respect to the d-line by the amount of deviation (unit: mm) from the paraxial image plane in the optical axis AX direction. The vertical axis represents the image height (IMG HT, unit: mm). In the distortion diagram, the horizontal axis represents distortion (unit:%) with respect to the d-line, and the vertical axis represents image height (IMG HT, unit: mm).

  When each embodiment is used as a projection optical system LN in a projector (for example, a liquid crystal projector) PJ (FIG. 11), the screen surface (projected surface) SC is originally the image surface and the image display surface IM2 (for example, the liquid crystal panel surface). ) Is an object plane, but in each embodiment, each is a reduction system in optical design, and the screen surface SC is regarded as an object plane (object) and an image display surface (reduction side image plane) IM2 corresponding to an image plane (image). Is evaluating the optical performance. Then, as can be seen from the obtained optical performance, the projection optical system LN of each embodiment is preferably used not only as a projection lens for a projector but also as an imaging lens for an image pickup device (for example, a video camera or a digital camera). It is possible.

Example 1
Unit: mm
Surface data
ird nd vd
object (SC) infinity infinity
1 90.156 7.600 1.69680 55.46
2 68.942 8.958
3 77.372 6.300 1.80518 25.46
4 57.955 10.706
5 75.518 15.482 1.83400 37.34
6 189.215 0.300
7 46.826 3.600 1.95375 32.32
8 28.471 8.916
9 45.662 2.200 1.91082 35.25
10 22.315 13.086
11 -47.332 1.700 1.80610 33.27
12 96.443 18.541
13 -185.734 6.284 1.72916 54.67
14 -50.205 23.295
15 72.913 5.079 1.80518 25.46
16 -121.426 25.611
17 -36.074 2.000 1.90366 31.31
18 96.763 2.021
19 116.400 10.344 1.43700 95.10
20 -33.431 0.300
21 56.049 10.256 1.43700 95.10
22 -65.165 0.300
23 130.344 2.100 1.90366 31.31
24 40.534 1.933
25 38.243 12.730 1.43700 95.10
26 -91.524 0.300
27 55.866 8.143 1.49700 81.61
28 -194.707 5.800
29 -42.901 2.300 1.62004 36.30
30 49.126 20.624
31 153.059 9.514 1.80518 25.46
32 -110.889 28.879
33 45.900 10.135 1.80518 25.46
34 84.076 8.021
35 (IM1) infinity variable
36 -56.931 6.217 1.80518 25.46
37 -38.496 3.351
38 -29.989 2.600 1.59282 68.62
39 -4276.234 16.378
40 -156.933 10.482 1.48749 70.44
41 -38.163 variable
42 19560.343 5.284 1.90366 31.31
43 -88.500 5.676
44 -46.639 2.400 1.80518 25.46
45 -104.689 1.552
46 -245.541 6.925 1.51680 64.20
47 -48.173 variable
48 (ST) infinity 6.255
49 -35.312 1.800 1.72916 54.67
50 137.215 19.192
51 -114.804 7.477 1.43700 95.10
52 -43.162 0.300
53 68.354 11.660 1.43700 95.10
54 -66.136 0.300
55 174.756 8.314 1.49700 81.61
56 -77.968 4.243
57 -55.771 2.400 1.69680 55.46
58 65.246 2.619
59 80.585 11.044 1.49700 81.61
60 -73.270 variable
61 89.211 6.565 1.49700 81.61
62 310 66.445 14.310
63 infinity 85.000 1.51680 64.20
64 infinity 5.000
65 infinity 3.000 1.48749 70.44
66 infinity 1.000
67 infinity 0.500
image (IM2) infinity

Various data
zoom ratio 1.26
Wide (W) Middle (M) Tele (T)
Fl -13.842 -15.544 -17.460
Fno. 2.422 2.500 2.597
ω 50.484 47.091 43.850
ymax 16.700 16.700 16.700
TL 610.095 610.097 610.098
BF 78.905 78.907 78.908
d35 34.762 33.700 34.093
d41 29.825 17.159 2.000
d47 28.215 32.565 35.606
d60 2.000 11.378 23.102

Zoom lens group data group (surface) focal length
1 (1-35) 22.265
2 (36-41) 832.800
3 (42-47) 105.175
4 (48-60) 132.289
5 (61-67) 180.003

Example 2
Unit: mm
Surface data
ird nd vd
object (SC) infinity infinity
1 98.016 7.600 1.69680 55.46
2 66.278 20.460
3 76.743 15.564 1.83400 37.34
4 165.373 0.300
5 49.189 3.600 1.95375 32.32
6 29.322 9.275
7 47.719 2.268 1.91082 35.25
8 22.358 13.331
9 -47.366 2.200 1.80610 33.27
10 80.640 18.545
11 -221.994 6.493 1.72916 54.67
12 -49.285 25.321
13 71.059 5.148 1.80518 25.46
14 -130.354 24.545
15 -38.565 2.000 1.90366 31.31
16 81.078 1.995
17 95.441 10.410 1.43700 95.10
18 -35.162 0.300
19 54.081 10.200 1.43700 95.10
20 -66.043 0.300
21 141.071 2.100 1.90366 31.31
22 40.441 1.887
23 37.999 12.742 1.43700 95.10
24 -86.935 0.300
25 60.957 7.966 1.49700 81.61
26 -146.956 5.531
27 -41.372 2.300 1.62004 36.30
28 47.827 20.088
29 146.201 10.309 1.80518 25.46
30 -104.508 30.673
31 45.250 10.075 1.80518 25.46
32 79.709 8.299
33 (IM1) infinity variable
34 -57.432 6.167 1.80518 25.46
35 -38.735 3.444
36 -29.772 2.441 1.59282 68.62
37 -8921.060 16.534
38 -156.608 10.454 1.48749 70.44
39 -37.932 variable
40 -859.442 5.266 1.90366 31.31
41 -81.849 5.289
42 -46.231 2.400 1.80518 25.46
43 -101.611 3.254
44 -364.986 7.097 1.51680 64.20
45 -49.543 variable
46 (ST) infinity 6.721
47 -35.421 1.300 1.72916 54.67
48 141.441 19.326
49 -120.382 7.443 1.43700 95.10
50 -43.995 0.300
51 69.854 11.444 1.43700 95.10
52 -66.691 0.300
53 185.279 8.152 1.49700 81.61
54 -78.804 4.189
55 -56.876 2.400 1.69680 55.46
56 66.695 2.642
57 83.143 10.893 1.49700 81.61
58 -73.489 variable
59 89.563 6.606 1.49700 81.61
60 -6373.246 14.300
61 infinity 85.000 1.51680 64.20
62 infinity 5.000
63 infinity 3.000 1.48749 70.44
64 infinity 1.000
65 infinity 0.500
image (IM2) infinity

Various data
zoom ratio 1.26
Wide (W) Middle (M) Tele (T)
Fl -13.842 -15.441 -17.460
Fno. 2.425 2.500 2.605
ω 50.547 47.342 43.906
ymax 16.700 16.700 16.700
TL 610.098 610.100 610.102
BF 78.898 78.900 78.902
d33 34.784 33.658 34.084
d39 29.580 17.929 2.000
d45 28.649 32.403 35.267
d58 2.000 11.025 23.663

Zoom lens group data group (surface) focal length
1 (1-33) 22.133
2 (34-39) 890.112
3 (40-45) 103.122
4 (46-58) 138.956
5 (59- 65) 177.771

Example 3
Unit: mm
Surface data
ird nd vd
object (SC) infinity infinity
1 113.972 7.600 1.69680 55.46
2 76.145 12.915
3 96.113 17.344 1.74330 49.22
4 237.926 0.300
5 59.857 4.600 1.80518 25.46
6 42.528 8.660
7 39.328 3.100 1.95375 32.32
8 28.136 8.267
9 41.274 2.200 1.91082 35.25
10 21.795 13.469
11 -43.567 1.902 1.80610 33.27
12 86.822 17.143
13 -221.976 6.680 1.72916 54.67
14 -47.580 22.574
15 73.778 5.069 1.80518 25.46
16 -123.734 26.245
17 -36.482 1.976 1.90366 31.31
18 94.586 2.000
19 112.160 10.045 1.43700 95.10
20 -32.510 0.300
21 53.640 9.904 1.43700 95.10
22 -68.070 0.300
23 120.981 2.100 1.90366 31.31
24 39.714 2.130
25 38.063 12.104 1.43700 95.10
26 -100.000 0.300
27 56.070 7.645 1.49700 81.61
28 -221.973 5.436
29 -44.497 2.067 1.62004 36.30
30 47.674 18.882
31 137.809 9.249 1.80518 25.46
32 -114.764 29.928
33 44.973 9.898 1.80518 25.46
34 77.388 8.418
35 (IM1) infinity variable
36 -62.065 6.379 1.80518 25.46
37 -39.732 3.310
38 -31.055 2.600 1.59282 68.62
39 -600.834 18.382
40 -122.509 9.720 1.48749 70.44
41 -38.985 variable
42 3001.226 6.318 1.90366 31.31
43 -94.610 9.768
44 -47.863 2.240 1.80518 25.46
45 -110.745 3.400
46 -333.913 5.982 1.51680 64.20
47 -49.306 variable
48 (ST) infinity 8.835
49 -36.446 1.773 1.72916 54.67
50 131.300 19.199
51 -206.992 7.387 1.43700 95.10
52 -45.301 0.300
53 67.914 10.615 1.43700 95.10
54 -69.606 0.521
55 223.533 7.627 1.49700 81.61
56 -80.914 4.105
57 -58.217 2.400 1.69680 55.46
58 66.014 2.682
59 84.544 10.007 1.49700 81.61
60 -76.823 variable
61 88.157 6.451 1.49700 81.61
62 17963.435 14.316
63 infinity 85.000 1.51680 64.20
64 infinity 5.000
65 infinity 3.000 1.48749 70.44
66 infinity 1.000
67 infinity 0.500
image (IM2) infinity

Various data
zoom ratio 1.26
Wide (W) Middle (M) Tele (T)
Fl -13.841 -15.441 -17.460
Fno. 2.428 2.500 2.620
ω 50.536 47.337 43.899
ymax 16.700 16.700 16.700
TL 610.095 610.098 610.098
BF 78.911 78.914 78.914
d35 35.815 34.835 35.182
d41 31.055 18.980 3.046
d47 21.560 25.799 28.941
d60 2.000 10.816 23.262

Zoom lens group data group (surface) focal length
1 (1-35) 22.292
2 (36-41) 680.261
3 (42- 47) 106.844
4 (48-60) 140.878
5 (61-67) 178.232

Example 4
Unit: mm
Surface data
ird nd vd
object (SC) infinity infinity
1 87.908 7.600 1.69680 55.46
2 68.136 10.534
3 80.771 6.300 1.80518 25.46
4 54.933 11.090
5 73.593 15.529 1.83400 37.34
6 213.311 0.300
7 45.495 3.600 1.95375 32.32
8 27.465 8.675
9 44.419 2.200 1.91082 35.25
10 22.726 12.642
11 -44.970 1.975 1.80610 33.27
12 103.763 18.567
13 -170.348 6.265 1.72916 54.67
14 -48.847 23.478
15 73.308 5.824 1.80518 25.46
16 -121.902 25.914
17 -35.528 2.000 1.90366 31.31
18 101.325 1.933
19 113.465 10.350 1.43700 95.10
20 -32.642 0.300
21 56.171 10.507 1.43700 95.10
22 -68.241 0.300
23 134.785 2.100 1.90366 31.31
24 40.565 1.799
25 37.844 13.038 1.43700 95.10
26 -96.769 0.300
27 52.827 8.483 1.49700 81.61
28 -198.237 5.860
29 -42.894 2.128 1.62004 36.30
30 48.466 20.933
31 148.819 9.139 1.80518 25.46
32 -121.593 28.222
33 45.232 9.408 1.80518 25.46
34 86.031 8.012
35 (IM1) infinity variable
36 -54.576 6.148 1.80518 25.46
37 -38.127 3.315
38 -29.907 2.100 1.59282 68.62
39 -3847.891 16.126
40 -148.818 10.220 1.48749 70.44
41 -37.467 variable
42 722.907 4.913 1.90366 31.31
43 -116.544 6.385
44 -51.529 1.900 1.80518 25.46
45 -107.942 1.037
46 -304.267 5.523 1.51680 64.20
47 -53.293 variable
48 (ST) infinity 6.637
49 -38.573 1.327 1.72916 54.67
50 121.786 19.246
51 -109.693 7.364 1.43700 95.10
52 -43.670 0.300
53 67.404 11.494 1.43700 95.10
54 -70.869 0.567
55 145.377 8.862 1.49700 81.61
56 -77.959 4.462
57 -56.429 2.400 1.69680 55.46
58 64.495 2.658
59 80.134 11.186 1.49700 81.61
60 -72.316 variable
61 89.450 6.650 1.49700 81.61
62 2595.869 14.450
63 infinity 85.000 1.51680 64.20
64 infinity 5.000
65 infinity 3.000 1.48749 70.44
66 infinity 1.000
67 infinity 0.500
image (IM2) infinity

Various data
zoom ratio 1.26
Wide (W) Middle (M) Tele (T)
Fl -13.842 -15.441 -17.460
Fno. 2.429 2.500 2.604
ω 50.416 47.310 43.922
ymax 16.700 16.700 16.700
TL 610.102 610.107 610.104
BF 79.053 79.057 79.055
d35 33.852 33.852 33.852
d41 31.384 17.501 2.000
d47 27.611 32.857 35.730
d60 2.075 10.712 23.339

Zoom lens group data group (surface) focal length
1 (1-35) 22.401
2 (36-41) 1096.173
3 (42-47) 112.213
4 (48-60) 123.064
5 (61-67) 186.239

Example 5
Unit: mm
Surface data
ird nd vd
object (SC) infinity infinity
1 63.021 4.600 1.69680 55.46
2 47.017 6.862
3 51.685 3.700 1.80518 25.46
4 38.689 10.500
5 61.270 10.834 1.83400 37.34
6 170.131 0.300
7 43.338 2.200 1.95375 32.32
8 20.155 7.336
9 37.612 1.600 1.91082 35.25
10 21.994 10.864
11 -22.916 1.400 1.80610 33.27
12 -1482.920 3.280
13 -78.679 7.539 1.72916 54.67
14 -26.919 11.399
15 84.901 5.695 1.80518 25.46
16 -64.979 27.030
17 -32.550 2.000 1.90366 31.31
18 106.035 2.406
19 217.315 10.242 1.43700 95.10
20 -28.539 0.300
21 75.797 11.706 1.43700 95.10
22 -48.765 0.300
23 174.439 2.100 1.90366 31.31
24 49.375 1.261
25 41.836 14.472 1.43700 95.10
26 -74.750 0.300
27 83.098 7.532 1.49700 81.61
28 -173.871 6.520
29 -42.107 1.833 1.62004 36.30
30 55.157 4.499
31 121.601 7.763 1.80518 25.46
32 -115.807 22.140
33 58.256 9.051 1.80518 25.46
34 195.627 21.360
35 (IM1) infinity 41.801
36 -62.957 7.185 1.80518 25.46
37 -35.672 4.264
38 -27.751 2.600 1.59282 68.62
39 680.906 6.318
40 -78.984 12.938 1.48749 70.44
41 -30.032 0.300
42 -310.077 5.755 1.90366 31.31
43 -74.326 6.279
44 -38.745 2.300 1.80518 25.46
45 -82.914 0.300
46 -659.397 8.588 1.51680 64.20
47 -44.718 46.990
48 (ST) infinity 8.073
49 -31.064 1.800 1.72916 54.67
50 102.425 8.112
51 -104.634 6.061 1.43700 95.10
52 -39.561 0.300
53 99.883 11.521 1.43700 95.10
54 -40.950 0.300
55 206.244 8.745 1.49700 81.61
56 -54.900 3.836
57 -44.015 2.400 1.69680 55.46
58 66.735 3.037
59 98.451 8.748 1.49700 81.61
60 -93.796 0.300
61 93.253 11.426 1.49700 81.61
62 -65.716 14.300
63 infinity 85.000 1.51680 64.20
64 infinity 5.000
65 infinity 3.000 1.48749 70.44
66 infinity 1.000
67 infinity 0.500
image (IM2) infinity

Various data
Fl -13.841
Fno. 2.500
ω 50.464
ymax 16.700
TL 540.092
BF 78.892
Ff 19.535
Fr 96.888

LN Projection optical system LN1 First optical system LN2 Second optical system Gr1 to Gr5 First to fifth lens groups ST Aperture stop IM1 Intermediate image (intermediate image plane)
IM2 image display surface (reduction side image surface)
PJ projector PR prism SC screen surface 1 light source 2 illumination optical system 3 reflection mirror 4 image display element 5 control unit 6 actuator AX optical axis

In order to achieve the above object, the projection optical system of the first invention is a projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more,
A first optical system and a second optical system in order from the enlargement side, the second optical system forms an intermediate image of the image, and the first optical system enlarges and projects the intermediate image;
The three lenses from the most magnifying side of the first optical system do not include an aspherical surface,
Zooming is performed by moving a lens group that is a part of at least one of the first and second optical systems along the optical axis to change the interval between the groups on the axis,
The second optical system has only a lens group that moves for zooming,
The second optical system has at least a second lens group, a third lens group, and a fourth lens group in order from the enlargement side as a lens group that moves for the magnification change.
Upon zooming from the wide-angle end to the telephoto end, the second lens group moves along a locus of convexity on the magnification side,
It is characterized in that the third lens group and the fourth lens group each move monotonically toward the enlargement side .

A projection optical system of a second invention is characterized in that, in the first invention, the following conditional expressions (1) and (2) are satisfied.
1.3 <Ff / | Fw | <2 (1)
0.4 <Lf / Lw <0.6 (2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.
The following characteristic configurations (# 1), (# 2) and the like are also included in the embodiments and the like described later.
(# 1): a projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more,
A first optical system and a second optical system in order from the enlargement side, the second optical system forms an intermediate image of the image, and the first optical system enlarges and projects the intermediate image;
A projection optical system characterized by satisfying the following conditional expressions (A1) and (A2);
1 <Ff / | Fw | <2 (A1)
0.4 <Lf / Lw <0.6 (A2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.
(# 2): The projection optical system according to (# 1), wherein the three lenses from the most magnifying side of the first optical system do not include an aspherical surface.

A projection optical system according to a ninth aspect is the projection optical system according to any one of the first to eighth aspects, wherein the second optical system has a fifth lens group on the reduction side of the fourth lens group, By using the first lens group as the optical system, the projection optical system has a positive, positive, positive, positive, and positive five-group zoom configuration, and the zoom positions of the first lens group and the fifth lens group are fixed. and said that you are.

A projector according to a tenth aspect of the invention is an image display device having the image display surface, and the projection according to any one of the first to ninth aspects of the invention, which enlarges and projects an image displayed on the image display surface onto a screen surface. And an optical system.

Hereinafter, the projection optical system, the projector, and the like according to the embodiments of the present invention will be described. A projection optical system according to an embodiment of the present invention is a projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more, and the first optical system in order from the magnifying side. System and a second optical system, the second optical system forms an intermediate image of the image, the first optical system magnifies and projects the intermediate image, and the following conditional expressions (1) and (2) are satisfied. The composition is satisfied.
1.3 <Ff / | Fw | <2 (1)
0.4 <Lf / Lw <0.6 (2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.

In the first embodiment (FIG. 1), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of positive, positive, and positive second lens groups Gr2 to Gr5 in order from the enlargement side. The scaling is performed only in the system LN2. When zooming is fixed to the first lens unit Gr1 is the fifth lens group Gr 5, in zooming from the wide-angle end (W) to the telephoto end (T), a locus of the second lens group Gr 2 is enlarged side convex moved, the third lens unit Gr3 fourth lens group Gr 4 monotonously moved to the respective magnification side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

In the second embodiment (FIG. 2), a total of 29 lens components are provided, 16 magnifying sides are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 magnifying sides. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of positive, positive, and positive second lens groups Gr2 to Gr5 in order from the enlargement side. The scaling is performed only in the system LN2. When zooming is fixed to the first lens unit Gr1 is the fifth lens group Gr 5, in zooming from the wide-angle end (W) to the telephoto end (T), a locus of the second lens group Gr 2 is enlarged side convex moved, the third lens unit Gr3 fourth lens group Gr 4 monotonously moved to the respective magnification side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

In the third embodiment (FIG. 3), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of positive, positive, and positive second lens groups Gr2 to Gr5 in order from the enlargement side. The scaling is performed only in the system LN2. When zooming is fixed to the first lens unit Gr1 is the fifth lens group Gr 5, in zooming from the wide-angle end (W) to the telephoto end (T), a locus of the second lens group Gr 2 is enlarged side convex moved, the third lens unit Gr3 fourth lens group Gr 4 monotonously moved to the respective magnification side. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

In the fourth embodiment (FIG. 4), a total of 30 lens components are provided, 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 is composed of a positive first lens group Gr1 as a whole, and the second optical system LN2 is composed of positive, positive, and positive second lens groups Gr2 to Gr5 in order from the enlargement side. The scaling is performed only in the system LN2. When zooming is fixed to the first lens unit Gr1 and the second lens group Gr 2 is the fifth lens group Gr 5, in zooming from the wide-angle end (W) to the telephoto end (T), and the third lens unit Gr3 The fourth lens group Gr 4 monotonously moves to the enlargement side. Therefore, the fourth embodiment is merely a form for reference of the present invention and does not belong to the present invention. The fourth lens group Gr4 has the aperture stop ST on the most enlargement side.

In the fifth embodiment (FIG. 5), a total of 30 lens components are provided, and 17 lenses on the magnifying side are the first optical system LN1 for magnifying and projecting the intermediate image IM1, and 13 lenses on the reducing side. Is the second optical system LN2 that forms the intermediate image IM1. The first optical system LN1 and the second optical system LN2 form a positive single focus lens as a whole. Therefore, the fifth embodiment is merely a form for reference of the present invention and does not belong to the present invention. The second optical system LN2 has an aperture stop ST near the reduction side of the largest air gap.

Hereinafter, the configuration and the like of the projection optical system embodying the present invention will be described more specifically with reference to the construction data and the like of the examples. Examples 1 to 5 (EX1 to 5) given here are numerical examples corresponding to the above-described first to fifth embodiments, respectively, and are optical configuration diagrams showing the first to fifth embodiments. (FIGS. 1 to 5) respectively show lens cross-sectional shapes, lens arrangements, etc. of corresponding Examples 1 to 5. Therefore, Examples 4 and 5 corresponding to the fourth and fifth embodiments are merely reference examples of the present invention and do not belong to the present invention.

Claims (11)

A projection optical system capable of magnifying and projecting an image displayed on an image display surface at a half angle of view of 40 ° or more,
A first optical system and a second optical system in order from the enlargement side, the second optical system forms an intermediate image of the image, and the first optical system enlarges and projects the intermediate image;
A projection optical system characterized by satisfying the following conditional expressions (1) and (2);
1 <Ff / | Fw | <2 (1)
0.4 <Lf / Lw <0.6 (2)
However,
Ff: focal length of the first optical system,
Fw: focal length of the entire system (when the projection optical system is a zoom lens, the focal length of the entire system at the maximum angle of view),
Lf: distance on the optical axis from the most enlarged side surface vertex of the first optical system to the intermediate image,
Lw: total lens length (when the projection optical system is a zoom lens, the total lens length at the maximum angle of view),
Is.   The projection optical system according to claim 1, wherein the three lenses from the most enlarged side of the first optical system do not include an aspherical surface.   The projection optical system according to claim 1 or 2, wherein the first optical system does not include an aspherical surface.   The projection optical system according to claim 1, wherein the projection optical system does not include an aspherical surface. The projection optical system according to any one of claims 1 to 4, wherein the following conditional expression (3) is satisfied:
0.8 <(Y ′ / Y) × β2 <1 (3)
However,
Y ': principal ray height from the optical axis at the intermediate image position of the most off-axis ray at the maximum angle of view,
Y: Maximum image height on the image display surface,
β2: paraxial magnification of the second optical system at the maximum angle of view (here, the paraxial magnification is [image size on image display surface] / [intermediate image size]),
Is.   The projection optical system according to any one of claims 1 to 5, wherein the most magnifying lens of the first optical system is a negative lens.   7. The projection optical system according to claim 1, wherein at least one positive lens is provided within three lenses from the most magnified side of the first optical system.   The projection optical system according to claim 1, wherein the first optical system has a negative lens, a negative lens, a positive lens, and a negative lens in order from the enlargement side.   9. The zooming is performed by moving a lens group formed of at least a part of at least one of the first and second optical systems along an optical axis. The projection optical system described.   10. The projection optical system according to claim 9, wherein only the second optical system has a lens unit that moves for the magnification change.   An image display device having the image display surface, and the projection optical system according to claim 1, which magnifies and projects an image displayed on the image display surface onto a screen surface. Characteristic projector.

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