JP2014098807A - Projection optical system and image display device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact projection optical system which allows for easily correcting trapezoidal distortion.SOLUTION: A projection optical system 30 for projecting light from an optical modulator 11 onto a projection surface includes, in order from the reduction side, a first optical system 31, a first reflective surface 14a, and a second optical system 32(17) and is configured such that; the first optical system 31 has refractive power; light from the first optical system 31 is reflected by the first reflective surface 14a to be guided to the second optical system 32; and either the first reflective surface 14a or the second optical system 32 is pivotable about a pivot axis 35 which is positioned at an intersection 15 between an optical axis P of the first optical system 31 and the first reflective surface 14a.

Description

  The present invention relates to a projection optical system and an image display device, and more particularly to an image display device that projects and displays an image generated by a light valve such as a digital micromirror device (hereinafter DMD).

An image display device that projects an image generated by a DMD or a liquid crystal panel on a screen is widely used. In particular, recently, a demand for a front projection type projector having an ultra-short projection distance is increasing as an image display device capable of displaying a large screen with a short projection distance. As a projection optical system that is a small-sized means for realizing an ultrashort projection distance, a projection optical system using a curved mirror is known.
For example, Patent Document 1 discloses a projection optical system configured by only a plurality of curved mirrors, and Patent Documents 2 and 3 disclose a projection optical system configured by combining a refractive optical system and a curved mirror. In both cases, ultra-short projection distance is achieved.

In the projection optical system having the ultra-short projection distance as described above, the projection light beam is projected from an oblique direction with respect to the projection surface to form an image, and in combination with the super wide angle, the image display device With a slight inclination, so-called trapezoidal distortion tends to occur in the projected image. In order to correct a trapezoidal distortion, which is a phenomenon in which an ideal image that should be a square is distorted into a trapezoid, conventionally, the attitude of the entire image display apparatus must be adjusted. However, as described above, in an optical system with an ultra short projection distance, a change in distortion with respect to tilt is sensitive, and there is a problem that adjustment is difficult. Further, it is possible to cancel the trapezoidal distortion by distorting the original video signal to be projected, but in this case, the resolution of the projected image is greatly deteriorated.
Patent Documents 2 and 3 disclose methods for adjusting trapezoidal distortion by setting a plane mirror between a concave mirror constituting a projection optical system and a screen and making the deflection angle of the mirror variable. However, since the angle of the light beam between the concave mirror and the screen is steep, changing the declination angle for adjustment changes the light beam significantly, and the effective diameter of the required mirror becomes very large, resulting in image display. This will increase the size of the device.
In view of the circumstances described above, an object of the present invention is to provide a projection optical system that is small and can easily correct trapezoidal distortion.

  To achieve the above object, a projection optical system according to the present invention is a projection optical system that projects light onto a projection surface from a light modulation element, and includes a first optical system and a first reflection surface from the reduction side. A second optical system, the first optical system has refractive power, light from the first optical system is reflected by the first reflecting surface and guided to the second optical system; The reflecting surface or the second optical system can be rotated, and the rotation axis passes through the point where the optical axis of the first optical system and the first reflecting surface intersect.

  According to the present invention, it is possible to provide a projection optical system that is small and can easily correct trapezoidal distortion.

The figure which shows the structure of Embodiment and Example 1 of an image display apparatus provided with the projection optical system which concerns on this invention. The figure which shows the state which the projection optical system shown in FIG. 1 inclined. The figure explaining the projection image with distortion and the ideal projection image without distortion. The figure which shows the state which installed the image display apparatus of Example 1 inclining. The figure which shows the state which installed the image display apparatus of Example 1 without inclining. The figure which shows an example of the means to rotate a 1st reflective surface automatically. The figure which shows the structure of Example 2 of the image display apparatus provided with the projection optical system which concerns on this invention. The figure which shows the state which installed the image display apparatus of Example 2 without inclining. The figure which shows the state which installed the image display apparatus of Example 2 inclining. The figure which shows the structure of Example 3 of the image display apparatus provided with the projection optical system which concerns on this invention.

  Hereinafter, embodiments and examples of a projection optical system and an image display device according to the present invention will be described with reference to the drawings. In the embodiments and examples, members having the same function are denoted by the same reference numerals, and redundant description is omitted.

  The features of the projection optical system 30 according to the embodiment include the following configuration as shown in FIG. An image forming unit 11 serving as a light modulation element that forms an image, and an image formed by the image forming unit 11 is enlarged and projected onto a screen surface 40a of a screen 40 serving as a projection surface. It has an optical system 31, a first reflecting surface 14a, and a second optical system 32. The first optical system 31 has refractive power, the optical elements 1a to 1p of the first optical system share the optical axis P, and the light from the first optical system 31 is transmitted to the first reflecting surface. The optical path is bent at 14 a and guided to the second optical system 32. The first reflecting surface 14a or the second optical system 32 is rotatable about an axis substantially perpendicular to the optical axis P as a rotation axis 35. The rotational axis 35 and the longitudinal direction of the image forming unit 11 (light modulation element) are substantially parallel. The rotation axis 35 is configured to pass through a point 15 (hereinafter referred to as “rotation center point”) where the optical axis P and the first reflection surface 14a intersect. In this embodiment, the first reflecting surface 14 a and the second optical system 32 are configured to be rotatable around the rotation center point 15. Such a projection optical system 30 is mounted in the apparatus main body 101 of the image display apparatus 100.

  With such a configuration, since the first reflecting surface 14a and the second optical system 32 are configured to be rotatable around the rotation center point 15, it is necessary to incline the entire image display device or to perform projection. There is no need to distort the video signal. Furthermore, since the change in the incident position of the light beam on the reflecting surface due to rotation can be suppressed, the required reflecting surface size can be reduced, small size, high performance, easy installation, and smooth correction of trapezoidal distortion. it can.

  Further, the first reflecting surface 14a can be reduced in size by disposing the first reflecting surface 14a in the vicinity of the intermediate image position by the first optical system. By adopting a layout in which the optical path is bent at the first reflecting surface 14a, the entire apparatus is reduced in size and the number of parts is reduced, which is advantageous in manufacturing. The arrangement position of the first reflecting surface 14a in this embodiment is preferable because the size of the reflecting surface that is required before and after the stop and before and after the intermediate image can be reduced. The arrangement position of the first reflecting surface 14a is not limited to this position. It is also conceivable to achieve this by moving the first reflecting surface 14a and the second optical system 32 independently.

  In the projection optical system 30, as a more preferable configuration, it is preferable that the first reflecting surface 14a and the second optical system 32 rotate independently. Referring to FIG. 1 as an example, the first reflecting surface 14a and the second optical system 32 are integrally moved about the rotation center point 15 (rotation shaft 35), thereby bringing the first reflection surface 14a and the second optical system 32 onto the screen 40 as shown in FIG. It is possible to correct the trapezoidal distortion of the projected image. However, by rotating the first reflecting surface 14a and the second optical system 32 independently, it becomes possible to correct the trapezoidal distortion with higher accuracy. More preferably, when the rotation angle of the first reflecting surface 14a is θ as shown in FIG. 2, the rotation angle of the second optical system 32 is 2θ. By satisfying such a condition, it becomes possible to correct the trapezoidal distortion with higher accuracy.

  The rotation angle θ of the first reflecting surface 14 a is preferably rotated according to the tilt amount of the apparatus main body 101. Further, regarding the tilt amount, for example, as shown in FIG. 4, when the plane perpendicular to the screen 40 (for example, the installation surface 50 such as a pedestal) is used as the reference plane, the tilt amount of the apparatus main body 101 from the reference plane is φ. Then, it is desirable that the rotation angle of the first reflecting surface 14a satisfies the formula (1) φ = 2θ. Thereby, the trapezoidal distortion caused by the inclination of the apparatus main body 101 can be corrected without degrading the resolution.

  Although the adjustment can be performed manually, for example, as shown in FIG. 6, an inclination amount detection means 110 for detecting the inclination amount φ of the apparatus main body 101, a rotation drive means 111 such as a servo motor, and a control unit 112 are provided. Provided in the apparatus main body 101, the rotation shaft 35 is connected to the rotation driving means 111. The tilt amount detection unit 110 and the rotation drive unit 111 are electrically connected to the control unit 112 via a signal line. Then, the control unit 112 controls the rotation angle and the rotation time of the rotation driving unit 111 according to the tilt amount detected by the tilt amount detection unit, the rotation angle θ of the first reflecting surface 14a, the second optical system. It is also possible to automatically adjust the trapezoidal distortion by controlling the rotation angle 2θ of 32. As the tilt detection means, for example, an acceleration sensor using MEMS (commonly known as MEMS) or a screen image can be taken with a camera, and the tilt can be calculated from the shape of trapezoidal distortion, but is not limited thereto.

  The trapezoidal distortion in the vertical and horizontal directions of the screen 40 can be corrected as follows. That is, the first reflecting surface 14a, which is perpendicular to the plane including the screen normal and the optical axis P, and in-plane direction perpendicular to the optical axis P and including the screen normal and the optical axis P is the axial direction of the rotation center point 15. Correction can be performed by rotating the second optical system 32. That is, it is only necessary to rotate the apparatus main body 101 in the same in-plane direction as the tilt direction with respect to the screen 40. More preferably, it is desirable that the rotation center point 15 is perpendicular to the plane including the optical axis P and the screen normal.

  Conventionally, as shown in FIG. 5, in order to adjust the trapezoidal distortion in the vertical direction of the screen with the installation posture of the apparatus main body 101 as shown in FIG. adjust. Alternatively, it is necessary to correct the inclination of the installation surface 50 of the image display device 100, which is not easy.

  In this embodiment, the second reflecting surface 17a is provided on the most enlarged side of the second optical system 32, and the second reflecting surface 17a is a concave reflecting surface. Then, an intermediate image conjugate with the image formed by the image forming unit 11 is formed on the enlargement side with respect to the first optical system 31, and enlarged and projected by the concave reflecting surface (second reflecting surface 17a). Thus, by using a concave reflecting surface for the second reflecting surface 17a located on the most enlarged side of the second optical system 32, the projection distance can be made very short. When the projection distance is shortened, the projection angle becomes steeper than that of a normal image display device, and a trapezoidal distortion is generated with a slight attitude error. Therefore, an adjustment mechanism for correcting this is required. For this reason, in this embodiment, the first reflecting surface 14a and the second optical system 32 are configured to be rotatable around the rotation center point 15.

  The concave reflecting surface that constitutes the second reflecting surface 17a is preferably an aspherical surface or a free-form surface. This is because the concave reflecting surface is aspherical or free-form surface, so that field curvature, distortion, etc. that occur in the intermediate image can be corrected, and the burden on the refractive optical system is reduced. This leads to an improvement.

  The projection optical system 30 preferably has a zoom mechanism (zoom lens) 22. This is because the screen size can be adjusted without moving the apparatus main body 101, and the ease of installation is further enhanced. By including the projection optical system 30 having such a configuration, it is possible to realize a projection-type image display device 100 that is small in size, high in performance, easy to install, and can smoothly correct trapezoidal distortion.

Next, a plurality of embodiments describing the projection optical system and the image display device in more detail will be described with reference to FIGS.
In each embodiment, the image forming unit 11 is a light valve such as “DMD”, “transmission type liquid crystal panel”, “reflection type liquid crystal panel”, and the portion indicated by reference numeral 11 is an image to be projected. This is the part to be formed. When the image forming unit 11 does not have a function of emitting light as in the case of DMD or the like, the image information formed in the image forming unit 11 is illuminated by illumination light from the illumination optical system 12 disposed in the apparatus main body 101. Is done. The illumination optical system 12 preferably has a function of efficiently illuminating the image forming unit 11. For example, a rod integrator or a fly eye integrator can be used to make the illumination more uniform. As a light source for illumination, a white light source such as an ultra-high pressure mercury lamp, a xenon lamp, a halogen lamp, or an LED can be used, and a monochromatic light source such as a single color light emitting LED or LD can also be used.

  In each embodiment, a DMD is assumed as the image forming unit 11. Each embodiment is premised on an image forming unit that does not have a function of emitting light by itself, but a self-light emitting type having a function of emitting a generated image can also be used. The parallel flat plate 13 disposed in the vicinity of the image forming unit 11 is assumed to be a cover glass (seal glass) of the image forming unit.

The meanings of symbols in each embodiment are as follows.
f: Focal length of entire system NA: Aperture efficiency ω: Half angle of view (deg)
R: radius of curvature (for aspheric surfaces, the paraxial radius of curvature)
D: Surface spacing Nd: Refractive index νd: Abbe number K: Aspherical conic constant Ai: i-th order aspherical constant The aspherical shape is the reciprocal of the paraxial radius of curvature (paraxial curvature): C, from the optical axis Height: H, conic constant: K, using the aspherical coefficients of the above orders, where X is the aspherical amount in the optical axis direction, and is expressed by the well-known equation 1, the paraxial radius of curvature and the conic constant The shape is specified by giving an aspheric coefficient.

  Reference numeral 201 denotes a first lens group, reference numeral 202 denotes a second lens group, reference numeral 203 denotes a third lens group, reference numeral 206 denotes an aperture stop, reference numeral 204 denotes a fourth lens group, and reference numeral 205 denotes a fifth lens group.

FIG. 1 is a cross-sectional view illustrating a configuration of the image display apparatus 100 according to the first embodiment and a locus of a difference between focusing and zooming of the lens group. In the image display device 100, a light beam that is two-dimensionally intensity-modulated by image information formed by the image forming unit 11 (DMD) becomes a projection light beam as object light.
The image display device 100 includes a projection optical system 30. The projection optical system 30 enlarges and projects the image formed by the image forming unit 11 and the image formed by the image forming unit 11 on a screen, and a first optical system 31 having a refractive power from the reduction side, and a first reflection. The surface 14a and the second optical system 32 are provided. The optical elements 1a to 1p constituting the first optical system 31 share the optical axis P, and the optical path is bent at the first reflecting surface 14a.
That is, the projected light beam from the image forming unit 11 passes through the first optical system 31, the optical path is bent by the first reflecting surface 14 a, and the image light beam passes through the second optical system 32. That is, the image information formed in the image forming unit 11 is displayed on the screen 40 shown in FIG. 5 as a projection image by the projection optical system 30. In this embodiment, the angle at which the optical path is bent is the vertical direction, but other angles may be used for miniaturization due to the layout of the entire image display apparatus. The first optical system 31 has a positive refractive power, and an intermediate image conjugated to image information formed in the image forming unit 11 is closer to the screen side than the first optical system, more specifically, the first optical system. An aerial image is formed between the optical element 1p constituting the system 31 and the second optical system 32. The intermediate image does not need to be formed as a planar image, and is formed as a curved surface image in this embodiment as well as in other embodiments.

  In the present embodiment, the mirror can be made smaller by disposing the flat plate-like first reflection mirror 14 provided with the first reflection surface 14a for bending the optical path at this position. In the present embodiment, the flat plate-like first reflection mirror 14 is used, but the present invention is not limited to this. Further, the arrangement position is preferably within the maximum effective diameter of the projection optical system 30 that functions to obtain a projection image. Further, the entire image display apparatus 100 can be reduced in size by bending the optical path.

  The second optical system 32 arranged on the most screen side is composed of an aspherical concave mirror 17 serving as an optical element, and an intermediate image is enlarged and projected by the aspherical concave mirror 17, and the screen 40 (FIGS. 4 and 5). Project). The intermediate image has field curvature and distortion, but this can be corrected by using an aspherical surface or free-form surface for the concave mirror. For this reason, the burden of aberration correction on the lens system is reduced, which increases the degree of design freedom and is advantageous for downsizing and the like.

  As shown in FIG. 5, if the screen 40 and the installation surface 50 of the image display device 100 are vertical, a projection image without trapezoidal distortion can be projected on the screen, and the projection optical system is designed in this way. That is, when the positional relationship between the screen surface 40a that is the projection surface and the image display device 100 is correct, a projection image without trapezoidal distortion can be projected on the screen. However, as shown in FIG. 4, the position of the screen 40 is the same as that in FIG. 5, and it is assumed that the installation surface 50 of the image display device 100 is tilted φ clockwise with respect to the screen 40. In this case, as shown in FIG. 3, what is supposed to be projected on the screen surface 40a as an ideal image without trapezoidal distortion is a trapezoidal distortion with a long lower side on the screen 40 and a shorter upper side as shown as a projected image. Produce.

  In such a case, conventionally, the shape of the projected image has been corrected by adjusting the posture of the image display device itself. However, in this embodiment, as shown in FIG. 2, the housing 16 and the first reflecting mirror 14 that support the second optical system 32 (aspherical concave mirror 17) are connected to the optical axis P and the first reflecting surface. Rotation adjustment is independently performed in a plane parallel to the drawing around the rotation center point 15 where 14a intersects. For this reason, it is possible to correct the shape of the projected image. Regarding the rotation amount of the housing 16 and the first reflection mirror 14, when the inclination of the image display device 100 is set to φ in the clockwise direction as described above, it is as follows. That is, the housing 16 supporting the second optical system 32 (aspherical concave mirror 17) may be simultaneously rotated by φ / 2 counterclockwise and the first reflecting mirror 14 by φ / 2 simultaneously counterclockwise.

  In this embodiment, the screen is illustrated with respect to the distortion in the vertical direction of the screen, but the same applies to the horizontal direction of the screen. However, as described above, the adjustment in the horizontal direction is relatively simple, and if the function of correcting both the vertical and horizontal directions is provided, the image display device 100 becomes complicated. As a configuration of the image display apparatus 100 in that case, for example, the first optical system 31, the aspherical concave mirror 17, and the first reflecting mirror 14 are supported by different supports, respectively, and the aspherical concave mirror 17 and the first The reflection mirrors 14 are connected to the same axis, and the axis is set as the rotation axis. A configuration in which the rotating shaft is supported by a column extending from the support body of the housing 16 or the first optical system 31 is conceivable, but is not limited thereto.

  The entire optical system and parts necessary for image formation, that is, an image processing unit, a power supply unit, a cooling fan (not shown) and the like are housed in the apparatus main body 101 shown in FIG. The apparatus 100 is comprised.

A specific configuration of the projection optical system 30 is shown below.
As shown in FIG. 1, the projection optical system 30 has the following configuration in order from the image forming unit 11 side to the screen side. First lens group 201 having positive refractive power, second lens group 202 having positive refractive power, third lens group 203 having negative refractive power, fourth lens group 204 having positive refractive power, negative A fifth lens group 205 having refractive power. A first reflecting mirror 14 that bends the optical path by 90 degrees, and an aspherical concave mirror 17 on the most screen side of the fifth lens group 205. The projection optical system 30 has an aperture stop 206 between the first lens group 21 and the second lens group 22, and only the second lens group 202 moves to the screen side along the optical axis P during zooming from enlargement to reduction. To do. Further, the focusing with respect to the variation of the projection distance moves the third lens group 203 and the fourth lens group 204 along the optical axis P to the reduction side when focusing from the short distance side to the long distance side.

The first lens group 201 includes a negative meniscus lens 1a having a convex surface facing the image forming unit, a biconvex lens 1b having a strong convex surface facing the screen, a positive meniscus lens 1c having a convex surface facing the image forming unit, and an image forming unit. It consists of a cemented lens of a negative meniscus lens 1d with a convex surface facing the side. In the first lens group 201, a negative meniscus lens 1a, a biconvex lens 1b, a positive meniscus lens 1c, and a negative meniscus lens 1d are arranged in this order from the image forming unit 11 side.
The second lens group 202 is composed of a plurality of cemented lenses. The first cemented lens is a cemented lens of a negative meniscus lens 1e having a convex surface facing the image forming unit, a biconvex lens 1f having a strong convex surface facing the screen, and a negative meniscus lens 1g having a convex surface facing the screen. The second cemented lens is a cemented lens of a biconvex lens 1h having a stronger convex surface toward the image forming unit and a positive meniscus lens 1i having a convex surface toward the screen.
The third lens group 203 includes a negative meniscus lens 1j having a convex surface facing the image forming unit, a negative meniscus lens 1k having a convex surface facing the image forming unit, and a positive meniscus lens 1l having a convex surface facing the image forming unit. And a biconcave lens 1m with a strong concave surface facing the screen side.
The fourth lens group 204 includes a positive meniscus lens 1n having a convex surface facing the screen.
The fifth lens group 205 includes two negative meniscus lenses 1o and 1p having a convex surface facing the screen and both surfaces being aspherical. Tables 1 to 4 show the configuration of each lens group.

FIG. 7 is a cross-sectional view illustrating the configuration of the image display apparatus 100A according to the second embodiment and a locus of differences in focusing and zooming between lens groups. Although the basic configuration is the same as that of the first embodiment, the position of the first reflecting mirror 24 having the first reflecting surface 24a for bending the optical path is different from that of the first embodiment.
Specifically, the image display device 100A includes optical elements 2a to 2d, an aperture stop 206, a first reflecting surface 24a, and a second optical component that form the first optical system 31A from the image forming unit 11 toward the screen. A projection optical system 30A including optical elements 2e to 2q constituting the system 32A is provided. Arranging the first reflecting mirror 24 immediately after the aperture stop 206 is advantageous in reducing the size of the first reflecting mirror 24.

The image display apparatus 100A forms an image formed by the image forming unit 11 with the optical elements 2a to 2p, and forms an intermediate image between the aspheric lens 2p that is the optical element and the concave aspherical mirror 18. Then, an image without distortion is projected onto the screen 40 shown in FIG.
As shown in FIGS. 8 and 9, the first reflecting surface 24 a and the second optical system (2 e to 2 p and the aspherical concave mirror 18) are supported by the housing 16. Corresponding to the inclination φ with respect to the installation surface 50 of the image display device 100A, the housing 16 rotates as follows. That is, the optical axis P shared by the optical elements 2a to 2d of the first optical system 31A and the rotation center point 25 where the first reflecting surface 24a intersects are rotated independently in a plane parallel to the drawing. . Thereby, the trapezoidal distortion shown in FIG. 3 can be corrected. In the present embodiment, the rotation axis 35 is configured as an axis substantially perpendicular to the optical axis P so as to pass through the rotation center point 25.

A specific configuration of the projection optical system 30A is shown below.
The projection optical system 30A has the following configuration in order from the image forming unit side to the screen side. The first lens group 201 having positive refractive power, the first reflecting mirror that bends the optical path by 90 degrees, the second lens group 202 having positive refractive power, the third lens group 203 having negative refractive power, and positive refraction A fourth lens group 204 having power, a fifth lens group 205 having negative refractive power, and an aspherical concave mirror 18. The projection optical system 30A has an aperture stop 206 between the first lens group 201 and the first reflection mirror, and only the second lens group 202 moves to the screen side along the optical axis P during zooming from enlargement to reduction. To do. When focusing from the short distance side to the long distance side, the third lens group 203 and the fourth lens group 204 move to the reduction side along the optical axis.

The first lens group 201 includes a negative meniscus lens 2a having a convex surface facing the image forming unit, a biconvex lens 2b having a strong convex surface facing the screen, a positive meniscus lens 2c having a convex surface facing the image forming unit, and an image forming unit. It consists of a cemented lens of a negative meniscus lens 2d with a convex surface facing the side. In the first lens group 201, a negative meniscus lens 2a, a biconvex lens 2b, a positive meniscus lens 2c, and a negative meniscus lens 2d are arranged in this order from the image forming unit 11 side.
The second lens group 202 is composed of a plurality of cemented lenses. The first cemented lens is
This is a cemented lens of a negative meniscus lens 2e having a convex surface facing the image forming unit, a biconvex lens 2f having a strong convex surface facing the screen, and a negative meniscus lens 2g having a convex surface facing the screen. The second cemented lens is a cemented lens of a biconvex lens 2h having a stronger convex surface on the screen side and a positive meniscus lens 2i having a convex surface on the screen side.
The third lens group 203 includes a negative meniscus lens 2j having a convex surface facing the image forming portion, a positive meniscus lens 2k having a convex surface facing the image forming portion, and a positive meniscus lens 2l having a convex surface facing the image forming portion. And a biconcave lens 2m having a strong concave surface facing the image forming unit side.
The fourth lens group 204 includes a positive meniscus lens 2n with a convex surface facing the screen side.
The fifth lens group 205 includes a negative meniscus lens 2o having a convex surface facing the screen and both surfaces being aspheric, and a negative meniscus lens 2p having a convex surface facing the image forming unit and both surfaces being aspheric. Tables 5 to 8 show the configuration of each lens group.

FIG. 10 is a cross-sectional view illustrating a configuration of an image display device 100B according to Example 3 of the present invention, and a diagram illustrating a locus of differences between focusing and zooming of a lens group. In the third embodiment, the first reflecting surface 24 and the second optical system 32A (the optical elements 2e to 2p and the aspherical concave mirror 18 constituting the second reflecting member) are integrally formed with the rotation center point 25 (the rotation axis). 35) The configuration is the same as that of the second embodiment except that it is configured to rotate around 35).
In the present embodiment, the first reflecting surface 24a and the second optical system 32A are supported by the same support member 26, and the optical axes P of the optical elements 2a to 2d constituting the first optical system 31A and the first optical system P. The point of intersection with the first reflecting surface 24a is rotated as a rotation center point 25 (rotation axis 35). In this case, the correction amount is smaller than that in the case where the first reflecting surface 24a and the second optical system 32A rotate independently, but the first reflecting surface 24a and the second optical system 32A are independent. Compared with the case 16 having the casing 16 shown in Example 2, the apparatus configuration is simplified, which is preferable.

DESCRIPTION OF SYMBOLS 10, 10A, 10B Image display apparatus 11 Light modulation element (image formation part)
14a, 24a First reflective surface 15, 25 Point where optical axis and first reflective surface intersect 17a, 18a Second reflective surface (concave reflective surface)
31, 31A First optical system 32, 32A Second optical system 30, 30A Projection optical system 35 Rotating shaft 40a Projected surface P Optical axis φ Amount of tilt of image display device main body

JP 2008-145703 A JP 2009-058935 A JP 2010-197837 A

Claims (12)

A projection optical system that projects light from a light modulation element onto a projection surface,
Comprising a first optical system, a first reflecting surface and a second optical system from the reduction side;
The first optical system has a refractive power, and light from the first optical system is reflected by the first reflecting surface and guided to the second optical system,
The first reflecting surface or the second optical system is rotatable, and a rotation axis thereof passes through a point where the optical axis of the first optical system and the first reflecting surface intersect with each other. .   The projection optical system according to claim 1, wherein the rotation axis and the longitudinal direction of the light modulation element are substantially parallel.   The projection optical system according to claim 1, wherein the first optical system has a plurality of optical elements, and the plurality of optical elements share an optical axis.   4. The projection optical system according to claim 1, wherein the first reflecting surface and the second optical system rotate independently.   5. The projection optical system according to claim 1, wherein when the rotation angle of the first reflecting surface is θ, the rotation angle of the second optical system is 2θ.   6. The projection optical system according to claim 1, wherein the rotation of the first reflecting surface and the second optical system is rotated according to the amount of inclination of the image display apparatus main body. The projection optical system according to claim 6, wherein the following expression is satisfied when an inclination amount of the image display device body is φ:
φ = 2θ (1)   The rotation center of the first reflecting surface and the second optical system is in a direction perpendicular to the surface including the optical axis and the projection surface normal line. The projection optical system described in 1.   The second optical system has a second reflecting surface on the most enlarged side, the reflecting surface is a concave reflecting surface, and an intermediate image conjugate with an image formed by the light modulation element is used for the first optical system. The projection optical system according to claim 1, wherein the projection optical system is formed on an enlargement side with respect to the system and is enlarged and projected by the concave reflecting surface.   The projection optical system according to claim 9, wherein the concave reflecting surface is an aspherical surface or a free-form surface.   The projection optical system according to claim 1, wherein the projection optical system is a zoom lens.   An image display apparatus comprising the projection optical system according to claim 1.

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