Projection optical system and image projection apparatus
阅读说明：本技术 投影光学系统及图像投影装置 (Projection optical system and image projection apparatus ) 是由 宫健二 于 2019-08-28 设计创作，主要内容包括：一种投影光学系统及图像投影装置,投影光学系统是从缩小侧到放大侧依次配置第一折射光学系统、反射光学系统及第二折射光学系统而成的,反射光学系统具有凹面镜,第一折射光学系统具有将显示于图像显示元件的图像的中间图像成像于凹面镜的缩小侧的功能,第二折射光学系统为透镜系统,且具有一个以上非球面,将第一折射光学系统的光轴作为基准光轴,并将图像显示元件的有效图像显示区域中以距基准光轴最远的位置为物点的主光线作为最外角主光线,从最外角主光线入射凹面镜的位置到基准光轴之间的光路长度DM、在第二折射光学系统中从最外角主光线朝向配置于最靠近放大侧的透镜的入射面的入射位置到基准光轴之间的光路长度DR满足第一条件。(A projection optical system is formed by arranging a first refractive optical system, a reflective optical system and a second refractive optical system in this order from a reduction side to an enlargement side, the reflective optical system having a concave mirror, the first refractive optical system having a function of forming an intermediate image of an image displayed on an image display element on the reduction side of the concave mirror, the second refractive optical system being a lens system and having one or more aspherical surfaces, the optical axis of the first refractive optical system being a reference optical axis, a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element being an outermost angle principal ray, an optical path length DM from a position where the outermost angle principal ray enters the concave mirror to the reference optical axis, and an optical path length DR from a position where the outermost angle principal ray enters the concave mirror toward an incident surface of a lens arranged closest to the enlargement side in the second refractive optical system to the reference optical axis being a full of optical path length DR from the position where the outermost angle principal ray enters the concave mirror to the reference optical axis The first condition is satisfied.)
1. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
an optical axis of the first refractive optical system is taken as a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element is taken as an outermost-angle principal ray,
an optical path length DM from a position where the outermost angle principal ray is incident on the concave mirror to the reference optical axis, and an optical path length DR from an incident position of the outermost angle principal ray toward an incident surface of a lens disposed closest to the magnification side in the second refractive optical system to the reference optical axis satisfy a first condition: 0.2< DR/DM < 3.0.
2. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
an optical axis of the first refractive optical system is taken as a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element is taken as an outermost-angle principal ray,
the height Y of the incident position of the outermost angle chief ray to the incident surface of the lens closest to the enlargement side from the reference optical axisLBA height Y from the outermost angle principal ray on the mirror surface of the concave mirror of the reflection optical system to the reference optical axisMRThe second condition is satisfied: 0.2<YLB/YMR<3.5。
3. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system having one or more aspherical surfaces,
a maximum height Yi between the reference optical axis and an effective image display area, and a distance OAL on the reference optical axis from a lens surface closest to the image display surface side to a mirror surface of the concave mirror satisfy a third condition: 5.0< OAL/Yi < 30.0.
4. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refractive optical system, a reflective optical system and a second refractive optical system in this order from the reduction side to the enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
focal length f of the first refractive optical system1AThe focal length f of the whole system meets the fourth condition: 0.04<f/f1A<0.5。
5. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
an optical axis of the first refractive optical system is taken as a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element is taken as an outermost-angle principal ray,
from the reference lightA maximum height Yi from the axis to the effective image display area, a height Y of the outermost angle principal ray on the concave mirror from the reference optical axisMRThe fifth condition is satisfied: 1.5<YMR/Yi<5.0。
6. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
taking an optical axis of the first refractive optical system as a reference optical axis and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element as an outermost-angle principal ray, and when the intermediate image is defined by a distance from a vertex of a lens closest to an enlargement side to a position closer to the image display surface among positions where a principal ray and an upper or lower ray intersect at each image height in the first refractive optical system,
in the effective image display area, an intermediate image position TA at an image height closest to the reference optical axis, and an intermediate image position TB at an image height farthest from the reference optical axis satisfy a sixth condition: 0.10< TB/TA < 0.80.
7. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
an optical axis of the first refractive optical system is taken as a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element is taken as an outermost-angle principal ray,
an angle θ of the outermost angle chief ray reflected by the concave mirror with respect to the reference optical axis satisfies a seventh condition: 1.5< tan θ < 10.0.
8. A projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface,
the projection optical system is formed by arranging a first refraction optical system, a reflection optical system and a second refraction optical system in sequence from a reduction side to an enlargement side,
the reflection optical system has a concave mirror,
the first refractive optical system has a function of imaging an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror,
the second refractive optical system is a lens system and has one or more aspherical surfaces,
the projection optical system satisfies any two or more of the following first to seventh conditions,
an optical axis of the first refractive optical system is taken as a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element is taken as an outermost-angle principal ray,
assuming that an optical path length from a position where the outermost angle principal ray is incident on the concave mirror to the reference optical axis is DM, and an optical path length from an incident position of the outermost angle principal ray toward an incident surface of a lens disposed closest to the magnification side in the second refractive optical system to the reference optical axis is DR, a first condition is 0.2< DR/DM <3.0,
the height of the incident position of the outermost-angle chief ray facing the incident surface of the lens closest to the magnification side from the reference optical axis is YLBThe height from the outermost angle principal ray on the mirror surface of the concave mirror of the reflection optical system to the reference optical axis is YMRThe second condition is 0.2<YLB/YMR<3.5，
Assuming that a maximum height between the reference optical axis and the effective image display area is Yi, and a distance on the reference optical axis from a lens surface closest to the image display surface side to a mirror surface of the concave mirror is OAL, a third condition is 5.0< OAL/Yi <30.0,
let f be the focal length of the first refractive optical system1AThe focal length of the whole system is f, and the fourth condition is 0.04<f/f1A<0.5，
Setting the maximum height from the reference optical axis to the effective image display area as Yi, and the height from the outermost angle chief ray on the concave mirror to the reference optical axis as YMRThe fifth condition is 1.5<YMR/Yi<5.0，
When the intermediate image is defined by a distance from a vertex of a lens closest to the magnification side to a position closer to the image display surface among positions where a principal ray and an upper or lower ray intersect at each image height in the first refractive optical system, in the effective image display area, the intermediate image position at the image height closest to the reference optical axis is set to TA, the intermediate image position at the image height farthest from the reference optical axis is set to TB, a sixth condition is 0.10< TB/TA <0.80,
let the angle of the outermost-angle principal ray reflected by the concave mirror with respect to the reference optical axis be θ, and a seventh condition be 1.5< tan θ < 10.0.
9. An image projection apparatus comprising:
an image display element; and
a projection optical system that projects an image displayed on the image display element as an enlarged image on a projection surface,
the image projection apparatus having the projection optical system according to any one of claims 1 to 8 as the projection optical system.
Technical Field
The present invention relates to a projection optical system and an image projection apparatus.
Background
"image projection apparatus" is widely known as a projector apparatus, and various proposals have been made for this.
Various types of projection optical systems have been proposed as a type used for an image projection apparatus to project an image displayed on an image display element as an enlarged image on a projection surface, and as one type thereof, there is known a type including a refractive optical system and a reflective optical system having refractive power, which reflects an imaging light beam emitted from the refractive optical system disposed on the image display element side by the reflective optical system and forms an image on the projection surface (
Patent document 1: japanese patent application 2014-80509
Disclosure of Invention
The invention aims to realize a novel projection optical system with a refraction optical system and a reflection optical system.
A projection optical system of the present invention is a projection optical system for projecting an image displayed on an image display element as an enlarged image on a projection surface, the projection optical system being formed by arranging a first refractive optical system, a reflective optical system and a second refractive optical system in this order from a reduction side toward an enlargement side, the reflective optical system having one concave mirror, the first refractive optical system having a function of imaging an intermediate image of the image displayed on the image display element on the reduction side of the concave mirror, the second refractive optical system being a lens system and having one or more aspherical surfaces, the optical axis of the first refractive optical system being a reference optical axis, and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display area of the image display element being an outermost angle ray, an optical path length DM from a position where the outermost principal ray is incident on the concave mirror to the reference optical axis, and an optical path length DR from an incident surface of a lens disposed closest to the magnification side in the second refractive optical system to the reference optical axis satisfy a first condition: 0.2< DR/DM < 3.0.
According to the present invention, a novel projection optical system having a refractive optical system and a reflective optical system can be realized.
Drawings
Fig. 1 is a diagram for explaining
Fig. 2 is a diagram for explaining
Fig. 3 is a diagram for explaining
Fig. 4 is a diagram for explaining
Fig. 5 is a diagram for explaining
Fig. 6 is a diagram for explaining
Fig. 7 is a diagram for explaining
Fig. 8 is a diagram for explaining
Fig. 9 is a diagram for explaining
Fig. 10 is a diagram showing data of example 1.
Fig. 11 is a diagram showing aspherical surface data of example 1.
Fig. 12 is an aberration diagram of example 1.
Fig. 13 is a graph showing data of example 2.
Fig. 14 is a diagram showing aspherical surface data of example 2.
Fig. 15 is an aberration diagram of example 2.
Fig. 16 is a diagram showing data of example 3.
Fig. 17 is a diagram showing aspherical surface data of example 3.
Fig. 18 is an aberration diagram of example 3.
Fig. 19 is a diagram showing data of example 4.
Fig. 20 is a diagram showing aspherical surface data of example 4.
Fig. 21 is an aberration diagram of example 4.
FIG. 22 is a data chart showing example 5.
Fig. 23 is a diagram showing aspherical surface data of example 5.
Fig. 24 is an aberration diagram of example 5.
Fig. 25 is a diagram showing data of example 6.
Fig. 26 is a diagram showing aspherical surface data of example 6.
Fig. 27 is an aberration diagram of example 6.
Fig. 28 is a diagram showing data of example 7.
Fig. 29 is a diagram showing aspherical surface data of example 7.
Fig. 30 is an aberration diagram of example 7.
Fig. 31 is a diagram showing data of example 8.
Fig. 32 is a diagram showing aspherical surface data of example 8.
Fig. 33 is an aberration diagram of example 8.
Fig. 34 is a diagram showing data of example 9.
Fig. 35 is a diagram showing aspherical surface data of example 9.
Fig. 36 is an aberration diagram of example 9.
Fig. 37 is a graph listing values of parameters representing conditions in examples 1 to 9.
Description of the reference numerals
10 … an image display surface of the image display element; elm … effective image display area; 11 … color synthesis prism; i … first refractive optical system; II … reflective optical system (concave mirror); III … second refractive optical system.
Detailed Description
Before explaining specific embodiments, the structure of the present invention will be explained.
The projection optical system of the present invention has the following "basic structure".
That is, a projection optical system in which a first refractive optical system, a reflective optical system, and a second refractive optical system are arranged in this order from a reduction side to an enlargement side, and a "reflective optical system" having one concave mirror projects an image displayed on an image display element as an enlarged image on a projection surface.
The "first refractive optical system" has a diaphragm in the system, and has a function of forming an intermediate image of an image displayed on the image display element on the reduction side of the concave mirror.
The "second refractive optical system" is a lens system having one or more aspherical surfaces.
Since the second refractive optical system is a lens system, it can be constituted by one or more lenses. Note that the reduction side is the image display element side, and the enlargement side is the projected surface side.
In this basic configuration, the optical axis of the first refractive optical system is set as a "reference optical axis", and a principal ray having a position farthest from the reference optical axis as an object point in an effective image display region of the image display element is set as an "outermost-angle principal ray".
The "effective image display region" refers to an area region displayed in the display surface of the image display element "an image that should be projected as an enlarged image by the projection optical system".
In this case, an optical path length DM from a position where the outermost principal ray is incident on the concave mirror to the reference optical axis, and an optical path length DR from an incident surface of a lens disposed closest to the magnification side in the second refractive optical system to the reference optical axis satisfy a condition (1): 0.2< DR/DM <3.0, and the structure of the projection optical system is referred to as "
In the basic structure, a height Y from the reference optical axis to an incident position from an outermost-angle principal ray toward an incident surface of the lens closest to the enlargement sideLBA height Y of the outermost angle principal ray from the reference optical axis on the mirror surface of the concave mirror of the reflection optical systemMRSatisfies the condition (2): 0.2<YLBYMR<3.5. The structure of the projection optical system in this case is referred to as "
In the basic configuration, a maximum height Yi between the reference optical axis and an effective image display area, and a distance OAL on the reference optical axis from a lens surface closest to the image display surface side to a mirror surface of the concave mirror satisfy a condition (3): 5.0< OAL/Yi < 30.0. The structure of the projection optical system at this time is referred to as "
In the basic structure, the first refractive optical systemFocal length f of1AAnd the focal length f of the whole system meets the condition (4): 0.04<f/f1A<0.5. The structure of the projection optical system at this time is referred to as "
In the basic configuration, a maximum height Yi from the reference optical axis to the effective image display area, a height Y from the outermost angle principal ray of the concave mirror to the reference optical axisMRSatisfies the condition (5): 1.5<YMR/Yi<5.0. The structure of the projection optical system at this time is referred to as "
In the basic structure, when the intermediate image is defined by a distance from a vertex of a lens closest to the magnification side in the first refractive optical system to a position closer to the image display surface among positions where a principal ray and an upper or lower ray intersect at each image height, an intermediate image position TA at an image height closest to the reference optical axis and an intermediate image position TB at an image height farthest from the reference optical axis in the effective image display area satisfy a condition (6): 0.10< TB/TA < 0.80. The structure of the projection optical system at this time is referred to as "
In the basic structure, an angle θ of the outermost angle chief ray reflected to the concave mirror with respect to the reference optical axis satisfies a condition (7): 1.5< tan θ < 10.0. The structure of the projection optical system at this time is referred to as "
In the basic structure, a structure of the projection optical system that satisfies two or more of the above-described conditions (1) to (7) is referred to as "
An image projection apparatus of the present invention includes: and a projection optical system that projects an image displayed on the image display element onto a projection surface as an enlarged image. As the projection optical system, any of the above-described
Next, the meanings of the conditions (1) to (7) will be explained.
If the parameter DR/DM of the condition (1) exceeds the lower limit value, the second refractive optical system and the concave mirror come close, and therefore, a disadvantage in "aberration correction" such as field curvature, distortion, or the like may occur. In addition, if the upper limit value is exceeded, the distance between the second refractive optical system and the concave mirror becomes long, which is advantageous in terms of aberration correction. However, this tends to increase the size of the second refractive optical system, and even the projection optical system.
If the parameter Y of the condition (2)LB/YMRIf the value exceeds the lower limit, the second refractive optical system and the concave mirror approach each other, and therefore, disadvantages in "aberration correction" such as field curvature and distortion may occur. In addition, if the upper limit value is exceeded, the second refractive optical system will become a direction away from the optical axis, which is advantageous in terms of aberration correction. However, this tends to increase the size of the second refractive optical system, and even the projection optical system.
If the parameter OAL/Yi of the condition (3) exceeds the lower limit value, the total length of the projection lens with respect to the image size becomes short, so that it will become difficult to correct aberrations such as field curvature. In addition, if the upper limit value is exceeded, aberration correction is facilitated. However, the distance from the incident surface of the first refractive optical system to the concave mirror increases, and the projection optical system is likely to be increased in size.
If the parameter f/f of the condition (4)1AIf the lower limit value is exceeded, the focal length f of the first refractive optical system is set1AThe focal length f with respect to the entire system becomes large, making it difficult to widen the angle. If the upper limit value is exceeded, the focal length f of the first refractive optical system1AThe focal length f with respect to the entire system becomes small, which is advantageous for the wide-angle. However, since the light beam emitted from the first refractive optical system is formed into an intermediate image in front of the concave mirror, the mirror surface size of the concave mirror becomes large, and the entire projection optical system is likely to be large in size.
If the parameter Y of the condition (5)MRif/Yi exceeds the lower limit, the size of the concave mirror becomes smaller with respect to the effective image display area, which is advantageous for downsizing the concave mirror. However, the concave mirror has a small magnification, which is disadvantageous in aberration correction and wide-angle. If the upper limit value is exceeded, the ruler of the concave mirrorThe size will become larger, which is advantageous for aberration correction. However, this easily leads to an increase in the size of the projection optical system.
If the parameter TB/TA of the condition (6) exceeds the lower limit value, the intermediate image position on the outermost-angle principal ray is displaced from the intermediate image position at the image height close to the reference optical axis, whereby the beam diameter will be widened on the mirror surface of the concave mirror, which is advantageous for aberration correction, but this easily causes the concave mirror to become large in size. If the upper limit value is exceeded, the intermediate image position on the outermost-angle principal ray will be close to the intermediate image position at the image height of the optical axis, which is advantageous for miniaturization of the concave mirror, but the beam diameter on the concave mirror will be narrowed, which is disadvantageous for aberration correction.
The condition (7) is a condition advantageous for widening the angle of the projection optical system, and the range of the condition (7) is suitable as the value of the parameter tan θ.
Hereinafter, embodiments of the present invention will be described.
Fig. 1 to 9 show a main part of the image projection apparatus, that is, a structure of an image display surface and an effective image display area in an image display element and a projection optical system.
Fig. 1 to 9 correspond to
To avoid complexity, the symbols are commonly used in fig. 1 to 9.
That is, regarding the projection optical system, the first refractive optical system is denoted by symbol I, the reflective optical system is denoted by symbol II, and the second refractive optical system is denoted by symbol III. Although in
In fig. 1 to 9,
In the embodiments shown in fig. 1 to 9, it is assumed that a "color enlarged image" is projected on a projection surface (generally, a "screen", hereinafter also referred to as a screen), and three liquid crystal panels are used as image display elements.
Needless to say, the image display element is not limited to a liquid crystal panel, and a DMD (digital micromirror device) or the like may be used.
On three liquid crystal panels assumed as image display elements, color component images corresponding to images of three primary colors, for example, R (red), G (green), and B (blue) are displayed, respectively, and illumination is performed by light of each color, so that a transmitted light beam or a reflected light beam forms image light of each color.
The above image lights of each color are synthesized by a "color synthesizing prism" denoted by a
Next, an example of
In
In the data of each example, "i" represents the surface number of the surface (surface including the aperture) counted on the enlargement side, where 0 is the surface of the
"R" represents a radius of curvature of each surface, "D" represents a surface pitch, "j" represents a number of the optical element, "Nd" represents a refractive index of a D-line of a material of the optical element, and "vd" represents an abbe number of the D-line.
In addition, the aspherical surface employed in each of the embodiments is represented by well-known following formula.
[ number 1]
Note that, in each of the embodiments, the effective image display region EIm provided on the
In the up-down direction of the figure, that is, the "width direction", the effective image display region having a rectangular shape is located at a position closer to the upper side in the figure than the reference optical axis as a whole.
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