JP2014098750A - Projection optical system and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection optical system having a small throw ratio.SOLUTION: A projector optical system 30A includes; a first lens group 51 which positively refracts modulated light ML; a second lens group 61 which negatively refracts incident light from the first lens group 51; and a concave mirror 32A which reflects incident light from the second lens group 61 toward a projection surface. A distance Lb between an apex of a light exit surface of the second lens group 61 and a surface apex of the concave mirror 32A, a composite focal length f1 of the first lens group 51 and second lens group 61 combined, a maximum value of an angle φmax between a principal ray exiting from the concave mirror 32A and an optical axis AX, a maximum value of an angle θmax between a principal ray entering the concave mirror 32A and the optical axis AX, and a focal length f2 of a lens C1 having the strongest negative power among optical lenses constituting the second lens group 61 satisfy conditional expressions as follows; 4.20≤Lb/f1≤6.25, 1.85≤φmax/θmax≤2.20, -1.55≤f2/f1≤-1.00.

Description

  The present invention relates to a projection optical system for enlarging and projecting an optical image on a projection surface and a projection display apparatus having the projection optical system, and in particular, projection optics for enlarging and projecting an optical image generated by a spatial light modulator on the projection surface. The present invention relates to a system and a projection display device including the same.

  Projection display devices, also called projectors, are widely used as means for realizing a large screen at a relatively low cost. In general, a projection display apparatus includes a spatial light modulation element such as a digital micromirror device (DMD) or a liquid crystal element, and an optical image generated by the spatial light modulation element on a screen. A projection optical system for enlarging and projecting onto the projection surface. As a light source for supplying light to the spatial light modulation element, a lamp light source (for example, a high-pressure mercury lamp or a xenon lamp) has been mainstream, but recently, a high light source such as an LED (Light-Emitting Diode) or an LD (Laser Diode) is used. Brightness semiconductor light emitting devices are being adopted.

  In recent years, there has been a demand for a projection display device having a short projection distance to the screen in order to improve the installation space of the projection display system. In order to maintain a large screen while reducing the projection distance, it is necessary to employ a wide-angle lens as a lens constituting the projection optical system. For example, Japanese Patent Laid-Open No. 2008-225455 (Patent Document 1) discloses a front projection type projection optical system having a combination of a positive power refractive optical system and a concave mirror in order to realize a short projection distance (projection distance). A system is disclosed.

JP 2008-225455 A (FIG. 1, FIG. 5, FIG. 9, paragraphs 0047 to 0054, etc.)

  In general, a value called a throw ratio is used as an index for improving the efficiency of installation space. The slow ratio can be defined as the ratio of the projection distance to the screen size on the screen (projected image size). As the projection distance becomes shorter for a certain screen size, the value of the slow ratio becomes smaller. However, if the screen size is reduced as the projection distance is shortened, the value of the slow ratio does not become smaller. In conventional projection display devices, there is a limit to reducing the value of the slow ratio without increasing the size of the projection optical system. Therefore, the larger the screen size, the longer the projection distance and the wider the installation space. There was a problem that it was necessary.

  In view of the above, an object of the present invention is to provide a projection optical system having a small slow ratio and a projection display device including the same.

A projection optical system according to an aspect of the present invention receives modulated light emitted from a spatial light modulation element, enlarges and projects an optical image represented by the modulated light on a projection surface, and projects the projection image on the projection surface. A first lens group that refracts the modulated light with positive power; a second lens group that refracts incident light from the first lens group with negative power; A concave mirror facing the light exit surface of the two lens group and reflecting the incident light from the second lens group toward the projection surface to form an image, and the light exit surface of the second lens group; The distance between the surface vertex of the concave mirror is Lb, the combined focal length of the first lens group and the second lens group is f1, and the optical axis common to the second lens group and the concave mirror is The maximum value of the angle formed with the chief ray emitted from the concave mirror is φm x is a single lens or a combination lens having the strongest negative power among optical lenses included in the second lens group, where θmax is a maximum value of an angle formed between the principal ray incident on the concave mirror and the optical axis. Let f2 be the focal length of
4.20 ≦ Lb / f1 ≦ 6.25,
1.85 ≦ φmax / θmax ≦ 2.20, and
−1.55 ≦ f2 / f1 ≦ −1.00,
And the conditional expression is satisfied.

  A projection display device according to another aspect of the present invention includes an illumination device including a light source, a spatial light modulation element that spatially modulates light emitted from the illumination device according to an image signal, and the projection optical system. It is characterized by providing.

  According to the present invention, it is possible to provide a projection optical system with a small slow ratio by configuring the projection optical system so as to satisfy the conditional expression.

It is a figure which shows schematically the structure of the projection type display apparatus of embodiment which concerns on this invention. It is a figure which shows schematically the structure of the projection type display apparatus of embodiment which concerns on this invention. It is a figure which shows an example of a structure of the illumination mechanism of a projection type display apparatus. It is a figure which shows the other example of a structure of the illumination mechanism of a projection type display apparatus. 1 is a diagram illustrating a configuration of a projection optical system according to Embodiment 1. FIG. 1 is a diagram illustrating a configuration of a projection optical system according to Embodiment 1. FIG. It is a graph which shows the relationship between the refractive index nd and Abbe number (nu) d of a general optical material. 3 is a diagram illustrating an optical surface of a component of the projection optical system according to Embodiment 1. FIG. It is a figure which shows the optical parameter of Example 1 in a table format. It is a figure which shows the data value of the conic coefficient which defines the aspherical shape of the optical surface of Example 1, and an aspherical coefficient in a tabular form. It is a figure which shows the spot diagram of the light ray when Example 1 is used. 6 is a diagram illustrating a configuration of a projection optical system according to Embodiment 2. FIG. 6 is a diagram illustrating an optical surface of a component of a projection optical system according to Embodiment 2. FIG. It is a figure which shows the optical parameter of Example 2 in a table format. It is a figure which shows the data value of the conic coefficient which determines the aspherical shape of the optical surface of Example 2, and an aspherical coefficient in a table | surface form. It is a figure which shows the spot diagram of the light ray when Example 2 is used. 6 is a diagram illustrating a configuration of a projection optical system according to Embodiment 3. FIG. 6 is a diagram illustrating an optical surface of a component of a projection optical system according to Embodiment 3. FIG. It is a figure which shows the optical parameter of Example 3 in a table format. It is a figure which shows the data value of the conic coefficient which determines the aspherical shape of the optical surface of Example 3, and an aspherical coefficient in a table | surface form. It is a figure which shows the spot diagram of the light beam when Example 3 is used. FIG. 6 is a diagram illustrating a configuration of a projection optical system according to a fourth embodiment. FIG. 10 is a diagram illustrating optical surfaces of components of a projection optical system according to Embodiment 4. It is a figure which shows the optical parameter of Example 4 in a table format. It is a figure which shows the conic coefficient which defines the aspherical shape of the optical surface of Example 4, and the data value of an aspherical coefficient in tabular form. It is a figure which shows the spot diagram of the light ray when Example 4 is used. FIG. 10 is a diagram illustrating a configuration of a projection optical system according to a fifth embodiment. FIG. 10 is a diagram illustrating an optical surface of a component of a projection optical system according to a fifth embodiment. It is a figure which shows the optical parameter of Example 5 in a table format. It is a figure which shows the data value of the conic coefficient which defines the aspherical shape of the optical surface of Example 5, and an aspherical coefficient in a tabular form. It is a figure which shows the spot diagram of the light ray when Example 5 is used. FIG. 10 is a diagram illustrating a configuration of a projection optical system according to a sixth embodiment. FIG. 10 is a diagram illustrating an optical surface of a component of a projection optical system according to a sixth embodiment. It is a figure which shows the optical parameter of Example 6 in a table format. It is a figure which shows the conic coefficient which defines the aspherical shape of the optical surface of Example 6, and the data value of an aspherical coefficient in tabular form. It is a figure which shows the spot diagram of the light ray when Example 6 is used. FIG. 10 is a diagram illustrating a configuration of a projection optical system according to a seventh embodiment. FIG. 10 is a diagram illustrating optical surfaces of components of a projection optical system according to Embodiment 7. It is a figure which shows the optical parameter of Example 7 in a table format. It is a figure which shows the data value of the conic coefficient which defines the aspherical shape of the optical surface of Example 7, and an aspherical coefficient in a tabular form. It is a figure which shows the spot diagram of the light beam when Example 7 is used. FIG. 10 is a diagram illustrating a configuration of a projection optical system according to an eighth embodiment. FIG. 10 is a diagram illustrating an optical surface of a component of a projection optical system according to an eighth embodiment. It is a figure which shows the optical parameter of Example 8 in a table format. It is a figure which shows the data value of the conic coefficient and aspherical coefficient which define the aspherical shape of the optical surface of Example 8 in a tabular form. It is a figure which shows the spot diagram of the light beam when Example 8 is used. FIG. 10 is a diagram illustrating a configuration of a projection optical system according to a ninth embodiment. FIG. 20 is a diagram illustrating an optical surface of a component of a projection optical system according to a ninth embodiment. It is a figure which shows the optical parameter of Example 9 in a table format. It is a figure which shows the conic coefficient which defines the aspherical shape of the optical surface of Example 9, and the data value of an aspherical coefficient in tabular form. It is a figure which shows the spot diagram of the light beam when Example 9 is used. It is a figure which shows the value of conditional expression (1) thru | or (4) about Example 1 thru | or 9 in a table | surface form.

  Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

Overall configuration of the projection display device.
1 and 2 are diagrams schematically showing a basic configuration of a projection display apparatus 1 according to an embodiment of the present invention. FIG. 1 is a diagram showing the configuration of the projection display device 1 from the side (X-axis negative direction side), and FIG. 2 shows the configuration of the projection display device 1 from the front side (Z-axis positive direction side). It is a figure to display. Note that the illustrated X axis, Y axis, and Z axis are orthogonal to each other, the X axis direction coincides with the horizontal direction, and the Y axis direction coincides with the vertical direction.

  As shown in FIG. 1, the projection display apparatus 1 includes a spatial light modulation element (light valve) 20 that spatially modulates an incident light beam and outputs modulated light, and illumination light to the spatial light modulation element 20. The illumination mechanism 10 to be supplied and the projection optical system 30 that receives the modulated light emitted from the spatial light modulator 20 and generates projection light are provided. The projection optical system 30 enlarges and projects the optical image represented by the modulated light onto the projection surface 40p of the screen 40, and forms a rectangular projection image Pi on the projection surface 40p as shown in FIG. be able to.

  The spatial light modulator 20 is a reflective type that performs two-dimensional or three-dimensional variable control of illumination light characteristics (for example, phase, polarization state, intensity, or propagation direction) in accordance with a modulation control signal from the outside. It is a transmissive spatial light modulator. The spatial light modulator 20 can generate modulated light representing an optical image and output it to the projection optical system 30 by spatially modulating the illumination light in accordance with the modulation control signal. In this embodiment, it is assumed that a digital micromirror device (registered trademark), which is a reflective spatial light modulator, is used as the spatial light modulator 20, but the present invention is not limited to this. It is not something. For example, a transmissive liquid crystal element or a reflective liquid crystal element can be used instead of the DMD.

  The projection optical system 30 includes a projection lens group 31 and a concave mirror 32 arranged along the optical axis AX. The projection optical system 30 is configured as a superordinate concept of the projection optical systems 30A to 30I of the first to ninth embodiments described later. As will be described later, the projection lens group 31 includes a first lens group that refracts the modulated light emitted from the spatial light modulation element 20 with a negative power, and a light beam emitted from the first lens group with a positive power. And a second lens group to be refracted. The concave mirror 32 opposes the light exit surface of the projection lens group 31, and has a function of reflecting the exit light from the projection lens group 31 in the direction of the projection surface 40p to form an image.

  The illumination mechanism 10 may have a lamp light source such as a high-pressure mercury lamp or a xenon lamp that emits white light as an internal light source for generating illumination light, or has a longer life and maintenance than the lamp light source. You may have semiconductor light emitting element groups, such as a light emitting diode (LED: Light Emitting Diode) and a laser diode (LD: Laser Diode) which are easy to manage. The illumination mechanism 10 equalizes the light intensity of the light beam emitted from the internal light source, and then supplies the light beam to the spatial light modulator 20 as illumination light.

  FIG. 3 is a diagram illustrating an example of the configuration of the illumination mechanism 10 of the projection display device 1. In the example of FIG. 3, the illumination mechanism 10 includes a lamp light source 11, a light uniformizing element 14, a color wheel 15, a light guide optical system 16, and a reflection mirror 17. The light beam emitted from the lamp light source 11 enters the light uniformizing element 14. The light uniformizing element 14 equalizes the light intensity distribution in the cross section of the light beam incident from the incident end face of the light uniforming element 14 (that is, in a plane orthogonal to the optical axis of the light intensity uniformizing element 113), and then transmits the light flux. Exit. Here, it is desirable that the cross-sectional shape of the emitted light beam of the light uniformizing element 14 is formed to be similar to the rectangular shape of the light modulation surface of the spatial light modulation element 20.

  As the light homogenizing element 14, for example, a polygonal column made of a transparent optical material such as a fly-eye lens, a glass material or a transparent resin material formed by arranging a plurality of segmented single lenses two-dimensionally ( Rod) or a hollow pipe (light pipe) having a polygonal cross section having the side surface of the light reflecting mirror. The side surface of the polygonal column used as the light uniformizing element 14 is configured as a total reflection surface that causes total internal reflection of light at the interface between the optical material constituting the polygonal column and the external air.

  The color wheel 15 has a disk shape and has a light transmission region (color filter) of a plurality of colors (for example, red, green, blue, and white) arranged along the circumferential direction. The drive unit 13 such as a motor can rotate the color wheel 15 around its central axis under the control of the control unit 12. Thereby, the color wheel 15 can sequentially supply light beams of a plurality of colors in a time division manner according to the rotation speed. In addition, when using LED or LD which emits the light of multiple colors as an internal light source, the color wheel 15 does not necessarily need to be provided.

  The light beam that has passed through the color wheel 15 and the light guide optical system 16 is reflected by the reflection mirror 17 and then irradiates the light modulation surface of the spatial light modulation element 20. The spatial light modulation element 20 generates modulated light representing an optical image by spatially modulating the incident light beam from the reflection mirror 17 in accordance with the modulation control signal supplied from the control unit 12. Here, the control unit 12 generates a modulation control signal based on the image signal VS supplied from an external signal source (not shown), and supplies this modulation control signal to the spatial light modulation element 20. Further, the control unit 12 controls the operation of the spatial light modulator 20 according to the color of the light beam emitted from the color wheel 15.

  FIG. 4 is a diagram illustrating another example of the configuration of the illumination mechanism 10 of the projection display device 1. In the example of FIG. 4, the illumination mechanism 10 includes a lamp light source 11, a light uniformizing element 14, a color wheel 15, a light guide optical system 16, and an internal total reflection prism 18. The configurations of the lamp light source 11, the light uniformizing element 14, the color wheel 15 and the light guide optical system 16 in FIG. 4 are the configurations of the lamp light source 11, the light uniformizing element 14, the color wheel 15 and the light guide optical system 16 in FIG. Is almost the same.

  The internal total reflection prism 18 is configured by joining two triangular prisms 18A and 18B to each other via an air layer. As shown in FIG. 4, the light beam that has entered the triangular prism 18 </ b> B from the light guide optical system 16 is emitted toward the spatial light modulation element 20 after total internal reflection. Further, the modulated light that has entered the triangular prism 18B from the spatial light modulation element 20 passes through the triangular prisms 18B and 18A and then enters the projection lens group 31.

  In addition, the structure of the illumination mechanism 10 is not limited to the example shown in FIG.3 and FIG.4. When a plurality of monochromatic light sources such as LEDs or LD (for example, a plurality of semiconductor light emitting elements that emit light in the red, green, and blue wavelength regions) are used as the internal light source of the illumination mechanism 10, the illumination mechanism 10 is white. In order to obtain light, it is possible to have a synthesis optical system such as a dichroic mirror that synthesizes light emitted from the plurality of monochromatic light sources. In particular, when an LD is used as the internal light source, the F value (F number) of the projection lens group 31 can be increased while ensuring brightness because of the high directivity of the emitted light. Therefore, the projection lens group 31 and the concave mirror 32 can be reduced in size, and a small projection display device 1 can be realized.

Referring to FIG. 1, the reflection curved surface of the concave mirror 32 has a rotationally symmetric shape with the optical axis AX as the rotation axis, and the projection surface 40p of the screen 40 in FIG. 2 has a normal direction parallel to the optical axis AX. Have As shown in FIG. 1, the projection distance in the normal direction between the vertex of the reflection curved surface of the concave mirror 32 in the optical axis direction and the projection surface 40p is defined as La. Also, let D be the diagonal dimension of the projected image Pi as shown in FIG. Then, the ratio La / D of the projection distance La to the diagonal dimension D of the projected image Pi is defined as the slow ratio. At this time, the projection display apparatus 1 of the present embodiment can be configured so that the slow ratio La / D satisfies the following conditional expression (1).
0.14 ≦ La / D ≦ 0.20 (1)

  A part of the concave mirror 32 shown in FIG. 1 and FIG. 2 is cut out to avoid interference with light rays from the concave mirror 32 toward the screen 40, and the cut-out part is indicated by a dotted line. However, it is not limited to this. If there is no interference with the light beam from the concave mirror 32 toward the screen 40, it is not necessary to cut out a part of the concave mirror 32.

Embodiment 1 FIG.
Next, Embodiment 1 according to the present invention will be described. FIG. 5 is a diagram showing a configuration of the projection optical system 30A of the first embodiment. The projection optical system 30A includes a projection lens group 31A and a concave mirror 32A arranged along the optical axis AX. FIG. 5 shows a cut end face of the projection lens group 31A in the YZ plane including the optical axis AX and a cross section of the concave mirror 32A in the YZ plane.

  The projection lens group 31A includes a first lens group 51 having a positive power as a whole and a second lens group 61 having a negative power as a whole. The first lens group 51 includes a plurality of optical lenses L10 to L19, and includes an aperture stop 33 between the optical lenses L12 and L14. On the other hand, the second lens group 61 includes a plurality of optical lenses Z10 to Z15. The second lens group 61 refracts incident light from the first lens group 51 with negative power and outputs the refracted light to the concave mirror 32A.

  Both the projection lens group 31 and the concave mirror 32A have a rotationally symmetric shape. However, a part of the concave mirror 32A is cut out in order to avoid interference with a light beam traveling from the concave mirror 32A toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line. Further, a part of the optical lens Z15 constituting the second lens group 61 is also cut out to avoid interference with the light beam directed from the concave mirror 32A toward the screen 40, and the cut off ineffective portion is a dotted line. It is shown in

  The spatial light modulation element 20 is arranged such that the center of the light modulation surface of the spatial light modulation element 20 is shifted from the optical axis AX by an offset amount of the distance δ. In FIG. 5, the light beam emitted at the minimum object height (object height closest to the optical axis AX) on the light modulation surface of the spatial light modulator 20 and the maximum object height (object height farthest from the optical axis AX) are emitted. The optical paths of a plurality of light beams (modulated light ML) including the transmitted light beam are shown.

  In the second lens group 61, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z10 and two optical lenses Z11 and Z12. C1, a positive power optical lens Z13, and aspherical lenses Z14 and Z15 are arranged in this order. The aspheric lenses Z14 and Z15 can be made of a plastic material, and the optical lenses Z10 to Z13 other than the aspheric lenses Z14 and Z15 can be made of a glass material.

  The second lens group 61 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emitting surface of the first lens group 51 (image surface side lens surface of the optical lens L19) and the concave mirror 32A. An intermediate image (conjugated image) MI1 can be formed at a conjugate imaging position. A part of the intermediate image MI1 is formed in a region closer to the object plane than the light exit surface of the second lens group 61 (the image surface side lens surface of the aspherical lens Z15), as shown in FIG. Therefore, the intermediate image MI1 is formed so as to cross the front end portion of the second lens group 61. Further, the intermediate image MI1 is formed in a region on the opposite side of the arrangement region of the spatial light modulator 20 via the optical axis AX.

  The first lens group 51 receives a light beam emitted from each point of the spatial light modulator 20 at a predetermined spread angle determined by the F value, and refracts the light beam with positive power to reduce the spread angle of the light beam. can do. The second lens group 61 can expand the angle formed by the optical axis AX of the principal ray after condensing the ray incident from the first lens group 51. Here, the principal ray means a ray that passes through the center of the aperture stop 33 among rays emitted from the spatial light modulator 20.

  As shown in FIG. 5, a portion of the intermediate image MI1 that is relatively close to the optical axis AX is formed between the second lens group 61 and the concave mirror 32A, while the optical axis AX of the intermediate image MI1. The portion that is relatively far from is formed in a region closer to the object plane than the lens surface closest to the image plane of the second lens group 61 (image plane side lens plane of the aspherical lens Z15). Accordingly, the distance between the concave mirror 32A and the second lens group 61 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 61 and the concave mirror 32A. Therefore, the projection optical system 30A can be downsized.

  In the conventional projection optical system as disclosed in Patent Document 1, the height of the intermediate image increases as the object height increases. On the other hand, in the present embodiment, as shown in FIG. 5, as the object height in the spatial light modulator 20 increases, the image height of the intermediate image MI1 decreases. When the projection lens group 31A generates such a large curvature of field, when the power of the concave mirror 32A is increased in order to reduce the slow ratio La / D, the large curvature of field generated in the concave mirror 32A. Can be offset. Therefore, the concave mirror 32A can project the projection image Pi in which the curvature of field is well corrected on the projection surface 40p of the screen 40 while reducing the slow ratio La / D.

  Here, the concave mirror 32A greatly enlarges the intermediate image MI1 generated by the projection lens group 31A to form a projection image Pi that is optically conjugate with both the spatial light modulator 20 and the intermediate image MI1. The projected image Pi is formed in a region opposite to the region where the intermediate image MI1 is formed with respect to the optical axis AX, and is formed in a region on the same side as the spatial light modulator 20. If the projection surface 40p of the screen 40 is placed at the image formation position of the projection image Pi, the projection image Pi can be displayed on the projection surface 40p.

  If the projection optical system includes only an optical lens, it is difficult to correct lateral chromatic aberration and distortion when the optical lens is widened to reduce the slow ratio. On the other hand, as described above, when the projection optical system 30A is configured by a combination of the projection lens group 31A and the concave mirror 32A, the concave mirror 32A is disposed at a position away from the projection lens group 31A. It is also possible to satisfactorily correct lateral chromatic aberration and distortion while enlarging the angle of view of the intermediate image MI1 on the surface 40p with high power.

  Further, in order to avoid interference with the light beam directed from the concave mirror 32A toward the screen 40, a part of the concave mirror 32A and a part of the optical lens Z15 are cut away, so that the Y-axis direction of the projection optical system 30A The miniaturization is realized.

The projection optical system 30A is configured to satisfy the following conditional expressions (2) to (4).
4.20 ≦ Lb / f1 ≦ 6.25 (2)
1.85 ≦ φmax / θmax ≦ 2.20 (3)
−1.55 ≦ f2 / f1 ≦ −1.00 (4)

  In the conditional expression (2), as shown in FIG. 5, Lb is the front end of the second lens group 61 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32A. In the optical axis direction. F1 is the overall focal length of the projection lens group 31A, that is, the combined focal length of the first lens group 51 and the second lens group 61. Conditional expression (2) defines a preferable range of the ratio between the distance Lb from the projection lens group 31A to the concave mirror 32A and the focal length f1 of the projection lens group 31A.

  Here, the focal length f1 is calculated based on optical parameters (such as a refractive index, a radius of curvature of the lens surface, and a surface interval) of the optical lenses L10 to L19 and Z10 to Z13 other than the aspherical lenses Z14 and Z15. To do. When the aspherical lenses Z14 and Z15 are made of a plastic material, the contribution of the power of the plastic lens to the overall power of the projection lens group 31A is reduced in order to reduce the deterioration of the optical performance due to the shape change caused by temperature or humidity. It is desirable to reduce the value. This is more desirable as the outer diameter size of the plastic lens increases. Further, as will be described later, when there is a non-zero first-order term in the aspheric coefficients that define the lens surface shapes of the aspheric lenses Z14 and Z15, the focal length of the projection lens group 31A including the aspheric lenses Z14 and Z15. It is difficult to apply the concept of Therefore, it is difficult to apply the concept of focal length when the lens power is weak and there is a non-zero first-order term in the aspheric coefficient. Therefore, the lens is continuously arranged from the most enlargement side toward the reduction side. The large plastic aspherical lenses Z15 and Z14 having a large outer diameter are excluded from the calculation of the focal length f1.

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32A and the optical axis AX as shown in FIG. 6, and φmax is shown in FIG. As shown, this is the maximum value among the angles φ formed by the principal ray emitted from the concave mirror 32A and the optical axis AX. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 61. In the present embodiment, the combination lens C <b> 1 including the optical lenses Z <b> 11 and Z <b> 12 is a lens group having the strongest negative power in the second lens group 61.

  As shown in FIG. 5, the light exiting the projection lens group 31A and entering the concave mirror 32A spreads. Therefore, if the distance Lb becomes too large, the size of the concave mirror 32A must be increased, and the projection optics The system 30A is enlarged. Further, when the size of the concave mirror 32A is increased, the manufacturing cost of the concave mirror 32A is increased. Further, if the distance Lb is increased under the condition where the projection distance La is constant, the maximum angle of view (the maximum value of the angle between the normal line of the projection surface 40p of the screen 40 and the principal ray incident on the projection surface 40p). Therefore, it is difficult to correct various optical aberrations.

  Further, in order to correct distortion well, it is desirable that the size of the reflection curved surface of the concave mirror 32A is somewhat large. If the distance Lb is too small, the projection lens group 31A and the concave mirror 32A are close to each other. In this case, if it is attempted to secure the size of the concave mirror 32A to some extent, it becomes necessary to increase the power of the projection lens group 31A, and it becomes difficult to correct various optical aberrations including chromatic aberration of magnification. Further, there is a possibility that interference between the light directed from the concave mirror 32A toward the screen 40 and the second lens group 61 occurs.

  In the present embodiment, when the ratio Lb / f1 in conditional expression (2) is 4.20 or more, the projection lens group 31A and the concave mirror 32A are appropriately separated from each other, and various optical aberrations are appropriately corrected. Thus, the projection lens group 31A can be prevented from interfering with the light beam traveling from the concave mirror 32A toward the screen 40. On the other hand, when the ratio Lb / f1 is 6.25 or less, the concave mirror 32A can be easily downsized and its manufacturing cost can be easily reduced, and the optical angle can be properly corrected by keeping the angle of view within an appropriate range. Can do.

  Conditional expression (3) defines a preferable range of the magnification at which the angle formed by the principal ray and the optical axis AX is converted by the concave mirror 32A. If the maximum angle φmax of the reflected light is too small, the projection distance La increases and the slow ratio La / D increases. Alternatively, if the angle θ formed between the principal ray incident on the concave mirror 32A and the optical axis AX is too large, the power of the projection lens group 31A is so large that it is difficult to correct optical aberrations such as lateral chromatic aberration. On the other hand, if the maximum angle φmax is too large, it becomes difficult to correct various optical aberrations including lateral chromatic aberration and distortion as the slow ratio La / D decreases. If the maximum angle θmax of the incident light is too small, the power of the projection lens group 31 is weak, and the projection optical system 30A may increase in size as the distance from the projection lens group 31A to the concave mirror 32A increases. If the distance from the projection lens group 31A to the concave mirror 32A is made too small, the size of the concave mirror 32A becomes small and it becomes difficult to correct distortion and the like.

  In the present embodiment, the angular magnification φmax / θmax of conditional expression (3) is limited to a range of 1.85 or more and 2.20 or less, so that various optical aberrations are corrected appropriately and the projection optical system 30A. Increase in size can be suppressed.

  Conditional expression (4) defines a preferable range of power of the combination lens C1 having the strongest negative power among the optical lenses included in the second lens group 61. If the negative power of the combination lens C1 is too strong compared to the power of the projection lens group 31A, the diameters of the optical lenses Z13 to Z15 located on the image plane side (enlargement side) from the combination lens C1 increase, and the projection lens group It becomes difficult to correct various optical aberrations including lateral chromatic aberration occurring at 31A. At this time, if the size of the concave mirror 32A is constant, the distance from the projection lens group 31A to the concave mirror 32A becomes too small, and there is a possibility that interference between the light from the concave mirror 3 toward the screen 4 and the lens group 2 occurs. is there. Further, if the distance from the projection lens group 31A to the concave mirror 32A is constant, the size of the concave mirror 32A increases and the manufacturing cost of the concave mirror 32A increases.

  On the other hand, if the negative power of the combination lens C1 is too weak compared to the power of the projection lens group 31A, it is difficult to correct field curvature. At this time, if an attempt is made to secure the size of the concave mirror 32A to some extent, the projection optical system 30A can be enlarged as the distance from the projection lens group 31A to the concave mirror 32A increases. If the distance from the projection lens group 31A to the concave mirror 32A is constant, the size of the concave mirror 32A becomes small, and it becomes difficult to correct distortion.

  In the present embodiment, since the ratio f2 / f1 of conditional expression (4) is limited to a range of −1.55 or more and −1.00 or less, the distance from the projection lens group 31A to the concave mirror 32A is optimal. The increase in size of the concave mirror 32A can be suppressed, and various optical aberrations can be corrected appropriately.

  By the way, according to the third-order aberration theory, the curvature of field is proportional to the square of the angle of view, so correction of the curvature of field is important in a wide-angle lens system. In order to correct the curvature of field, it is necessary to reduce the Petzval sum using a strong negative power optical lens. The combination lens C1 has a relatively strong negative power. This makes it possible to correct the field curvature appropriately. In addition, the angle magnification φmax / θmax of the concave mirror 32A becomes an appropriate value by increasing the angle θ formed with the optical axis AX of the principal ray incident on the concave mirror 32A. Furthermore, the distance from the projection lens group 31A to the concave mirror 32A can be shortened.

  The positive-power optical lens Z10 reduces the angle formed by the optical axis AX of the chief rays emitted from the first lens group 51, and then causes the chief rays to enter the combined lens C1. As a result, the diameter of the second lens group 61 can be reduced, and even if a strong power is introduced to the second lens group 61, it is formed with the optical axis AX of the principal ray emitted from the second lens group 61. An excessive increase in the angle can be avoided.

  The optical lens Z13 having positive power makes the principal ray incident on the aspherical lens Z14 after reducing the angle formed with the optical axis AX of the principal ray emitted from the combination lens C1. Thereby, it is possible to avoid an excessive increase in the diameter of the aspheric lens Z14 and the sag amount z (r) of the lens surface of the aspheric lens Z14. Here, the sag amount z (r) is a value representing the surface shape of the aspheric lens according to an aspheric polynomial (8) described later. Further, the positive power optical lens Z13 is used to converge the light propagated from the spatial light modulator 20 to form the intermediate image MI1 shown in FIG.

  As described above, the second lens group 61 includes the optical lenses Z10 and Z13 disposed at the position where the combination lens C1 is sandwiched, so that the second lens group 61 is prevented from being enlarged and the sag amount z (r) increased. In addition, the curvature of field can be corrected favorably. In the present embodiment, each of the aspherical lenses Z14 and Z15 is a single lens, and the combination lens C1 is composed of two optical lenses Z11 and Z12. However, the present invention is not limited to this. Instead of the aspherical lens Z14, a plurality of optical lens groups having a positive power as a whole may be used, and instead of the aspherical lens Z15, a plurality of optical lenses having a positive power as a whole may be used. Is possible. A single lens having the same optical function may be used instead of the combination lens C1.

  By using the projection optical system 30A that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set to a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less). At this time, the projection distance La for the projection image size D is an appropriate value. When the slow ratio La / D is 0.14 or more, an extreme increase in the angle of view is suppressed, so that various optical aberrations such as lateral chromatic aberration and distortion can be corrected appropriately. On the other hand, when the slow ratio La / D is 0.20 or less, the installation space of the projection display system can be made compact.

All optical lenses Z10 to Z15 constituting the second lens group 61 of the present embodiment have the following conditional expressions (5) to (5) when the refractive index with respect to the d-line (wavelength 587.6 nm) of the lens material is nd. It is preferable that the optical material satisfy any one of (7) and nd ≦ 1.63.
νd ≦ −50nd + 120 (1.8 <nd) (5)
νd ≦ −149.25nd + 298.51 (1.7 <nd ≦ 1.8) (6)
νd ≦ −212.77nd + 406.38 (1.63 <nd ≦ 1.7) (7)

  Here, νd is an Abbe number with respect to the d-line of the lens material. The Abbe number is a value representing the inverse dispersion rate of the optical medium. When the Abbe number is large, the dispersion rate is low. The conditions of conditional expressions (5) to (7) and nd ≦ 1.63 are the preferable ranges of combinations of the refractive index nd and the Abbe number νd for the optical lenses Z10 to Z15 included in the second lens group 61. It is shown. Hereinafter, this point will be described.

  FIG. 7 is a graph showing the relationship between the refractive index nd and the Abbe number νd of a general optical material. In FIG. 7, x marks indicate glass materials containing rare earth elements such as lanthanum or tantalum as components, and black circles (●) indicate optical materials that do not contain rare earth elements. Regarding the relationship between the refractive index nd and the Abbe number νd, generally, the Abbe number νd tends to decrease as the refractive index nd increases. A glass material containing a rare earth element has a relatively high refractive index nd, and a glass material having a larger Abbe number νd can be selected for a refractive index nd of substantially the same value as compared with an optical material containing no rare earth element. For this reason, since the occurrence of chromatic aberration is low due to high refractive index and low dispersion, glass materials containing rare earth elements tend to be frequently used particularly in wide-angle lenses in which lateral chromatic aberration is a problem. However, the cost of the glass material is high because it contains rare earth elements with rare value. Therefore, if a glass material containing a rare earth element is used as a constituent material of the second lens group 61 having a larger diameter than that of the first lens group 51, the manufacturing cost of the second lens group 61 is increased. As the constituent material, it is preferable to use an optical material containing no rare earth element.

  As shown in FIG. 7, the glass material containing rare earth elements exists in a range where the refractive index nd is higher than the straight lines M1, M2, and M3, the refractive index nd is lower than the straight lines M1, M2, and M3, and nd ≦ It does not exist in the range satisfying 1.63. Therefore, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the conditional expressions (5) to (7) and nd ≦ 1.63 (hatched range in FIG. 7) is used. Thus, the manufacturing cost of the second lens group 61 can be suppressed.

  As described above, in the first embodiment, the projection optical system 30A that satisfies the conditional expressions (2) to (4) is used, so that the slow ratio La / D is small and optical aberrations are corrected well. Thus, a small projection display device 1 can be provided. Further, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 61. Thus, the manufacturing cost can be reduced.

Example 1
Next, an example of the projection optical system 30A according to Embodiment 1 (hereinafter also referred to as Example 1) will be described. FIG. 8 is a diagram showing optical surfaces s0 to s2, sa3 to sa31 of the components of the projection optical system 30A. The optical surface s0 represents the light modulation surface of the light modulation unit 21 of the spatial light modulation element 20, the optical surface s1 represents the light incident surface of the cover glass 22 of the spatial light modulation element 20, and the optical surface s2 represents the cover glass. 22 light output surfaces are shown. Optical surfaces sa3 to sa31 represent lens surfaces constituting the projection lens group 31A. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32A is sa32.

  9 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sa3 to sa31, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30A. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. As for the surface interval, for example, the surface interval (= 0.703 mm) corresponding to the light modulation unit 21 indicates the interval between the light modulation surface s0 and the light incident surface s1 of the cover glass 22, and corresponds to the lens surface sa4. The surface interval (= 1.396 mm) indicates the interval between the lens surfaces sa4 and sa5. The surface spacing corresponding to the concave mirror 32A is indicated by a value (= −309.320 mm) obtained by adding a minus sign to the distance between the reflection curved surface sa32 of the concave mirror 32A and the projection surface 40p of the screen 40. .

式（８）は、非球面多項式と呼ばれている。ここで、ｒは、光軸ＡＸに対して垂直なＸ−Ｙ平面内における当該光軸ＡＸからの高さ（単位：ミリメートル）であり、ｚ（ｒ）は、高さｒの点における光軸方向の面位置を表すサグ量である。また、ｋは、コーニック係数と呼ばれる値であり、Ｃは、面頂点での曲率であり、Ａ_ｉは、ｉ次の非球面係数（ｉは１以上Ｎ以下の整数）である。 In the table of FIG. 9, “AS” attached to the surface code means that the lens surface is an aspheric surface. The same applies to the tables of other drawings. In the case of the present embodiment, the lens surfaces sa28 to sa31 constituting the aspheric lenses Z14 and Z15 and the reflection curved surface sa32 of the concave mirror 32A each have an aspheric shape. The shapes of the lens surfaces sa28 to sa31 and the reflection curved surface sa32 are determined according to the following equation (8).

Equation (8) is called an aspheric polynomial. Here, r is the height (unit: millimeter) from the optical axis AX in the XY plane perpendicular to the optical axis AX, and z (r) is the optical axis at the point of the height r. This is a sag amount representing the surface position in the direction. Further, k is a value called a conic coefficient, C is a curvature at a surface vertex, and A _i is an i-order aspheric coefficient (i is an integer of 1 to N).

Figure 10 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface sa28~sa31 and reflection curved surface sa32 of this embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero. In the present specification, the value of “nE−m” indicates “n × 10 ^−m ”. For example, “1.0E-03” indicates “1.0 × 10 ⁻⁰³ ”.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 5.31 mm. The projection image size D is 107.4 inches, and the F number of the projection optical system 30A is F2.5.

  As shown in FIG. 8, in the first lens group 51, from the object plane side (reduction side) to the image plane side (enlargement side), a biconvex lens L10, a biconcave lens L11, biconvex lenses L12 and L13, Negative power meniscus lens L14 having a concave surface facing the enlargement side, biconvex lens L15, biconcave lens L16, positive power meniscus lens L17 having a convex surface facing the enlargement side, and negative power having a concave surface facing the reduction side A meniscus lens L18 and a positive-power meniscus lens L19 having a convex surface facing the reduction side are arranged in this order. The biconcave lens L11 and the biconvex lens L12 are cemented with each other, the meniscus lens L14 and the biconvex lens L15 are cemented with each other, and the biconvex lens L15 and the biconcave lens L16 are cemented with each other. An aperture stop 33 is provided between the biconvex lenses L12 and L13.

  In the second lens group 61, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z10 having a convex surface on the reduction side, biconcave lenses Z11 and L12, and on the enlargement side A positive power meniscus lens Z13 having a convex surface and plastic aspherical lenses Z14 and Z15 having both aspherical surfaces on both sides are arranged in this order. In order to avoid interference with the light emitted from the concave mirror 32A, a portion of the aspheric lens Z15 that does not contribute to the image formation of the projected image Pi is cut out. The negative lens group having the strongest negative power among the lens groups included in the second lens group 61, which is the target of the conditional expression (4), is a combination of the biconcave lenses Z11 and L12.

Aspheric lenses Z14, Z15, in order to ensure the freedom of aberration correction, as shown in the table of FIG. 10, the lens surface shape including an aspherical surface defined by the primary aspherical coefficients A ₁ non-zero sa28~ It has sa31. In the lens surfaces sa28 to sa31 including an aspheric surface determined by a non-zero first-order aspheric coefficient, the inclination of the lens surface is discontinuous at the lens center. By forming such an aspherical surface, there is an advantage that the degree of freedom in designing the lens surface shape is improved. However, if a light beam passes through a portion where the lens center has a discontinuous inclination, the imaging performance may be adversely affected. Therefore, the portion may be cut out.

  FIG. 11 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the first embodiment is used. The ratio of the weight to the wavelength of the light beam was 635 nm: 532 nm: 460 nm = 30: 59: 11. A set of numerical values (units: MM, millimeters) shown on the left side of each spot diagram indicates a combination of the X coordinate and the Y coordinate in the spatial light modulator 20. A set of numerical values respectively attached on the X coordinate and the Y coordinate indicate relative values of the X coordinate and the Y coordinate with respect to the maximum object height. FIG. 11 shows a total of 12 points including a point at the minimum object height, a point at the maximum object height, and 10 points between the minimum object height and the maximum object height when the X coordinate is set to zero. A spot diagram corresponding to the value of the Y coordinate for the object height is shown. As shown in FIG. 11, it can be seen that the optical aberrations are corrected appropriately and satisfactorily for 12 object heights.

Embodiment 2. FIG.
Next, a second embodiment according to the present invention will be described. FIG. 12 is a diagram illustrating a configuration of the projection optical system 30B according to the second embodiment. The configuration of the projection display apparatus of the second embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30B of FIG.

  The projection optical system 30B according to the present embodiment includes a projection lens group 31B and a concave mirror 32B arranged along the optical axis AX. FIG. 12 shows a cut end face of the projection lens group 31B in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32B in the YZ plane.

  The projection lens group 31B includes a first lens group 52 having a positive power as a whole and a second lens group 62 having a negative power as a whole. The first lens group 52 includes a plurality of optical lenses L20 to L26, and includes an aperture stop 33 between the optical lenses L22 and L23. On the other hand, the second lens group 62 includes a plurality of optical lenses Z20 to Z25. The second lens group 62 refracts incident light from the first lens group 52 with negative power and outputs the refracted light to the concave mirror 32B.

  Both the projection lens group 31B and the concave mirror 32B have a rotationally symmetric shape. However, a part of the concave mirror 32B is cut out in order to avoid interference with a light beam traveling from the concave mirror 32B toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line. Further, a part of the optical lens Z25 constituting the second lens group 62 is also cut out to avoid interference with the light beam from the concave mirror 32B toward the screen 40, and the cut off ineffective portion is a dotted line. It is shown in

  In the second lens group 62, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z20 and two optical lenses Z21 and Z22. C2, a positive power optical lens Z23, and aspherical lenses Z24 and Z25 are arranged in this order. The aspheric lenses Z24 and Z25 can be made of a plastic material, and the optical lenses Z20 to Z23 other than the aspheric lenses Z24 and Z25 can be made of a glass material.

  The first lens group 52 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 62 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emitting surface of the first lens group 52 (image surface side lens surface of the optical lens L26) and the concave mirror 32B. An intermediate image (conjugate image) MI2 is formed at the conjugate imaging position. A part of the intermediate image MI2 is formed in a region closer to the object plane than the light exit surface of the second lens group 62 (image surface side lens surface of the aspherical lens Z25), as shown in FIG. For this reason, the intermediate image MI <b> 2 is formed so as to cross the front end portion of the second lens group 62. Thereby, the distance between the concave mirror 32B and the second lens group 62 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 62 and the concave mirror 32B. Therefore, the projection optical system 30B can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31B of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 62 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32B. In the optical axis direction. F1 is the overall focal length of the projection lens group 31B, that is, the combined focal length of the first lens group 52 and the second lens group 62. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of the lens surface, surface interval, etc.) of the optical lenses L20 to L26 and Z20 to Z23 other than the aspherical lenses Z24 and Z25. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32B and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32B and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 62. In the present embodiment, the combination lens C <b> 2 including the optical lenses Z <b> 21 and Z <b> 22 is a lens group having the strongest negative power in the second lens group 62.

  By using the projection optical system 30B that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all the optical lenses Z20 to Z25 constituting the second lens group 62 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the 2nd lens group 62 can be suppressed.

  The optical lens Z22 constituting the combination lens C2 is an aspheric lens. In this optical lens Z22, an effective portion through which light is actually transmitted is located in a region that is biased downward from the center of the aspheric lens Z22. Accordingly, it is preferable to reduce the volume of the aspherical lens Z22 by notching the ineffective portion above the center. This is advantageous in terms of cost while ensuring the desired optical performance.

  Also in the second embodiment, since the projection optical system 30B that satisfies the conditional expressions (2) to (4) is used, a small projection display in which the slow ratio La / D is small and various optical aberrations are well corrected. A device 1 can be provided. Further, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 62. Thus, the manufacturing cost can be reduced.

(Example 2)
Next, an example of the projection optical system 30B according to the second embodiment (hereinafter also referred to as Example 2) will be described. FIG. 13 is a diagram showing optical surfaces s0 to s2, sb3 to sb25 of the components of the projection optical system 30B. Optical surfaces sb3 to sb25 represent lens surfaces constituting the projection lens group 31B. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32B is sb26.

  FIG. 14 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sb3 to sb26, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30B. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In this embodiment, the lens surfaces sb18 and sb19 constituting the optical lens Z22, the lens surfaces sb22 to sb25 constituting the aspheric lenses Z24 and Z25, and the reflection curved surface sb26 of the concave mirror 32B each have an aspheric shape. . The shapes of the lens surfaces sb18, sb19, sb22 to sb25, and the reflection curved surface sb26 are determined according to the above aspherical polynomial (8).

Figure 15 is a diagram showing a lens surface SB18, SB19 of the present embodiment, Sb22～sb25 and the data value of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the reflection curved surface sb26 in tabular form. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 5.31 mm. The projection image size D is 107.4 inches, and the F number of the projection optical system 30B is F2.5.

  As shown in FIG. 13, in the first lens group 52, a biconvex lens L20, a biconcave lens L21, a biconcave lens L22, and a biconvex lens from the object plane side (reduction side) to the image plane side (enlargement side). L23, a negative power meniscus lens L24 having a concave surface facing the enlargement side, a biconvex lens L25, and a negative power meniscus lens L26 having a concave surface facing the reduction side are arranged in this order. The biconcave lens L21 and the biconcave lens L22 are cemented with each other, the meniscus lens L24 and the biconvex lens L25 are cemented with each other, and the biconvex lens L25 and the meniscus lens L26 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L22 and the biconvex lens L23.

  In the second lens group 62, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z20 with a convex surface facing the reduction side, a biconcave lens Z21, and both surfaces are aspherical. The glass aspherical lens Z22, a positive power meniscus lens Z23 having a convex surface on the enlargement side, and plastic aspherical lenses Z24 and Z25 whose both surfaces are aspherical are arranged in this order. In order to avoid interference with the light emitted from the concave mirror 32B, the portion of the aspheric lens Z25 that does not contribute to the image formation of the projected image Pi is cut out.

  The negative lens group having the strongest negative power among the optical lenses Z20 to Z25 constituting the second lens group 62 is a combination of a biconcave lens Z21 and an aspheric lens Z22. In the high-power biconcave lens Z21, the light beam is greatly bent, so that a large aberration tends to occur. Therefore, by making the lens surface of the aspherical lens Z22 an aspherical shape, the aberration generated in the high-power biconcave lens Z21 is suppressed, and the aberration correction load in the other lenses Z23 to Z25 is reduced. As a result, in the second lens group 62 of the present embodiment, the number of lenses can be reduced by three compared to the second lens group 61 of the first embodiment.

  In general, when the diameter of the glass aspherical lens increases, the manufacturing cost increases and the surface accuracy deteriorates, making it difficult to ensure performance. In the present embodiment, the positive-power meniscus lens Z20 emits light to the biconcave lens Z21 after reducing the divergence angle of the light incident from the first lens group 52. Therefore, the biconcave lens Z21 and the glass aspheric lens Z22 are used. The diameter can be reduced. Therefore, even when the aspheric lens Z22 is made of a glass material, the manufacturing cost can be suppressed and the desired optical performance can be easily ensured.

  FIG. 16 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the second embodiment is used. The spot diagram of FIG. 16 is obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 16, it can be seen that the optical aberrations are corrected appropriately and satisfactorily with respect to the object height of 12 points.

Embodiment 3 FIG.
Next, a third embodiment according to the present invention will be described. FIG. 17 is a diagram showing a configuration of the projection optical system 30C of the third embodiment. The configuration of the projection display apparatus of the third embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30C of FIG.

  The projection optical system 30C of the present embodiment includes a projection lens group 31C and a concave mirror 32C arranged along the optical axis AX. FIG. 17 shows a cut end surface of the projection lens group 31C in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32C in the YZ plane.

  The projection lens group 31C includes a first lens group 53 having a positive power as a whole and a second lens group 63 having a negative power as a whole. The first lens group 53 includes a plurality of optical lenses L30 to L36, and includes an aperture stop 33 between the optical lenses L32 and L33. On the other hand, the second lens group 63 is composed of a plurality of optical lenses Z30 to Z36, and refracts incident light from the first lens group 53 with negative power and outputs it to the concave mirror 32C. Both the projection lens group 31C and the concave mirror 32C have a rotationally symmetric shape. However, a part of the concave mirror 32C is cut out in order to avoid interference with a light beam traveling from the concave mirror 32C toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line.

  In the second lens group 63, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z30 and two optical lenses Z31 and Z32. C3, an aspherical lens (intermediate aspherical lens) Z33, an optical lens Z34, and aspherical lenses Z35 and Z36 are arranged in this order. The aspheric lenses Z33, Z35, Z36 can be made of a plastic material, and the optical lenses Z30 to Z32, Z34 other than the aspheric lenses Z33, Z35, Z36 can be made of a glass material.

  As described above, when the aspherical lens Z22 is made of a glass material in the second lens group 62 of Embodiment 2, there is an effect of reducing the number of lenses, but when the lens diameter is large, the manufacturing cost is high. As the height increases, it becomes difficult to ensure desired optical performance. On the other hand, a plastic aspherical lens is easy to manufacture inexpensively even if it is relatively large compared to a glass aspherical lens, and it is easy to ensure desired optical performance. From this point of view, it is preferable that the aspherical lens Z33 disposed adjacent to the combination lens C3 and closer to the image plane side than the combination lens C3 is made of a plastic material. By adopting the plastic aspheric lens Z33, the second lens group 63 can obtain substantially the same effect as the second lens group 62 including the glass aspheric lens Z22.

  In the present embodiment, the number of lenses of the projection lens group 31C is two less than that of the projection lens group 31A of the first embodiment. A plastic material has a problem that the linear expansion coefficient and hygroscopicity are larger than those of a glass material, so that a shape change accompanying an environmental change such as temperature or humidity is large, and optical performance is easily deteriorated. In the present embodiment, as shown in FIG. 17, the power of the aspherical lens Z33 is weakened, and the lens surface of the aspherical lens Z33 is formed with a shape with less unevenness, thereby avoiding such a problem. Can do.

  The first lens group 53 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 63 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 53 (the image surface side lens surface of the optical lens L36) and the concave mirror 32C. An intermediate image (conjugated image) MI3 is formed at a conjugate imaging position. A part of the intermediate image MI3 is formed in a region closer to the object plane than the light exit surface of the second lens group 63 (the image surface side lens surface of the aspherical lens Z36), as shown in FIG. Therefore, the intermediate image MI3 is formed so as to cross the front end portion of the second lens group 63. Thereby, the distance between the concave mirror 32C and the second lens group 63 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 63 and the concave mirror 32C. Therefore, the projection optical system 30C can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31C of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 63 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32C. In the optical axis direction. F1 is the overall focal length of the projection lens group 31C, that is, the combined focal length of the first lens group 53 and the second lens group 63. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L30 to L36 and Z30 to Z34 other than aspherical lenses Z35 and Z36. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32C and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32C and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 63. In the present embodiment, the combination lens C <b> 3 including the optical lenses Z <b> 31 and Z <b> 32 is a lens group having the strongest negative power in the second lens group 63.

  By using the projection optical system 30C that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all of the optical lenses Z30 to Z36 constituting the second lens group 63 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the 2nd lens group 63 can be suppressed.

  Therefore, also in Embodiment 3, since the projection optical system 30C satisfying the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Furthermore, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 63. Thus, the manufacturing cost can be reduced.

(Example 3)
Next, an example (hereinafter also referred to as Example 3) of the projection optical system 30C according to Embodiment 3 will be described. FIG. 18 is a diagram showing optical surfaces s0 to s2, sc3 to sc27 of the components of the projection optical system 30C. The optical surfaces sc3 to sc27 represent lens surfaces constituting the projection lens group 31C. Although not shown, the sign of the reflection curved surface of the concave mirror 32C is sc28.

  FIG. 19 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sc3 to sc27, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30C. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the case of the present embodiment, the lens surfaces sc20 and sc21 constituting the optical lens Z33, the lens surfaces sc24 to sc27 constituting the aspheric lenses Z35 and Z36, and the reflection curved surface sc27 of the concave mirror 32C each have an aspheric shape. . The shapes of the lens surfaces sc20, sc21, sc24 to sc27 and the reflection curved surface sc28 are determined according to the above aspherical polynomial (8).

Figure 20 is a diagram showing a lens surface SC20, sc21 of the present embodiment, Sc24～sc27 and the data value of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the reflection curved surface sc28 in tabular form. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 5.31 mm. The projection image size D is 107.4 inches, and the F number of the projection optical system 30C is F2.5.

  As shown in FIG. 18, in the first lens group 53, from the object plane side (reduction side) to the image plane side (enlargement side), a biconvex lens L30, a biconcave lens L31, a biconvex lens L32, and a biconvex lens. L33, a negative power meniscus lens L34 having a concave surface facing the enlargement side, a biconvex lens L35, and a negative power meniscus lens L36 having a concave surface facing the reduction side are arranged in this order. The biconcave lens L31 and the biconcave lens L32 are joined to each other, the meniscus lens L34 and the biconvex lens L35 are joined to each other, and the biconvex lens L35 and the meniscus lens L36 are joined to each other. An aperture stop 33 is provided between the biconvex lens L32 and the biconvex lens L33.

  In the second lens group 63, from the object surface side (reduction side) to the image surface side (enlargement side), a biconvex lens Z30, biconcave lenses Z31 and Z32, and a plastic aspheric lens Z33 having both surfaces aspherical. Then, a positive power meniscus lens Z34 having a convex surface facing the reduction side and plastic aspherical lenses Z35 and Z36 having both aspherical surfaces on both sides are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z30 to Z36 constituting the second lens group 63 is a combination of biconcave lenses Z31 and Z32.

  FIG. 21 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the third embodiment is used. The spot diagram of FIG. 21 is obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 21, it can be seen that the optical aberrations are corrected appropriately and satisfactorily for 12 object heights.

Embodiment 4 FIG.
Next, a fourth embodiment according to the present invention will be described. FIG. 22 is a diagram showing a configuration of the projection optical system 30D of the fourth embodiment. The configuration of the projection display apparatus of the fourth embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30D of FIG.

  The projection optical system 30D according to the present embodiment includes a projection lens group 31D and a concave mirror 32D arranged along the optical axis AX. FIG. 22 shows a cut end face of the projection lens group 31D in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32D in the YZ plane.

  The projection lens group 31D includes a first lens group 54 having a positive power as a whole and a second lens group 64 having a negative power as a whole. The first lens group 54 includes a plurality of optical lenses L40 to L49, and includes an aperture stop 33 between the optical lenses L42 and L43. On the other hand, the second lens group 64 includes a plurality of optical lenses Z40 to Z45, refracts incident light from the first lens group 54 with negative power, and emits the light to the concave mirror 32D.

  Both the projection lens group 31D and the concave mirror 32D have a rotationally symmetric shape. However, a part of the concave mirror 32D is notched in order to avoid interference with the light beam traveling from the concave mirror 32D toward the screen 40, and the ineffective portion thus cut out is indicated by a dotted line. Further, part of the optical lenses Z44 and Z45 constituting the second lens group 64 is also cut out in order to avoid interference with the light beam from the concave mirror 32D toward the screen 40, and the cut out ineffective portion. Is indicated by a dotted line.

  In the second lens group 64, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z40 and two optical lenses Z41 and Z22. C4, a positive power optical lens Z43, and aspherical lenses Z44 and Z45 are arranged in this order. The aspheric lenses Z44 and Z45 can be made of a plastic material, and the optical lenses Z40 to Z43 other than the aspheric lenses Z44 and Z45 can be made of a glass material.

  The first lens group 54 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 64 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 54 (the image surface side lens surface of the optical lens L49) and the concave mirror 32D. An intermediate image (conjugate image) MI4 is formed at the conjugate imaging position. A part of the intermediate image MI4 is formed in a region closer to the object plane than the light exit surface of the second lens group 64 (image surface side lens surface of the aspherical lens Z45), as shown in FIG. Therefore, the intermediate image MI4 is formed so as to cross the front end portion of the second lens group 64. Thereby, compared with the case where all the intermediate images are formed between the 2nd lens group 64 and the concave mirror 32D, the distance between the concave mirror 32D and the 2nd lens group 64 can be made small. Therefore, the projection optical system 30D can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31D of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 64 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32D. In the optical axis direction. F1 is the overall focal length of the projection lens group 31D, that is, the combined focal length of the first lens group 54 and the second lens group 64. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L40 to L49, Z40 to Z43 other than aspherical lenses Z44 and Z45. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32D and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32D and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 64. In the present embodiment, the combination lens C <b> 4 including the optical lenses Z <b> 41 and Z <b> 42 becomes a lens group having the strongest negative power in the second lens group 64.

  By using the projection optical system 30D that satisfies the conditional expressions (2) to (4), the slow ratio La / D can be set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all of the optical lenses Z40 to Z45 constituting the second lens group 64 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the 2nd lens group 64 can be suppressed.

  Therefore, also in Embodiment 4, since the projection optical system 30D satisfying the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Further, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 64. Thus, the manufacturing cost can be reduced.

(Example 4)
Next, an example (hereinafter also referred to as Example 4) of the projection optical system 30D according to Embodiment 4 will be described. FIG. 23 is a diagram showing optical surfaces s0 to s2, sd3 to sd32 of the components of the projection optical system 30D. Optical surfaces sd3 to sd32 represent lens surfaces constituting the projection lens group 31D. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32D is sd33.

  FIG. 24 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sd3 to sd33, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30D. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the case of the present embodiment, the lens surfaces sd29 to sd32 constituting the aspheric lenses Z44 and Z45 and the reflection curved surface sd33 of the concave mirror 32D each have an aspheric shape. The shapes of the lens surfaces sd29 to sd32 and the reflection curved surface sd33 are determined according to the above aspherical polynomial (8).

Figure 25 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface sd29~sd32 and reflection curved surface sd33 of this embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 4.9 mm. The projected image size D is 60 inches, and the F number of the projection optical system 30D is F2.5. In this embodiment, the projected image size D is relatively small and the offset amount δ is also small.

  As shown in FIG. 23, in the first lens group 54, from the object plane side (reduction side) to the image plane side (enlargement side), a biconvex lens L40, a biconcave lens L41, a biconvex lens L42, and a biconvex lens. L43, a biconcave lens L44, a biconvex lens L45, a negative power meniscus lens L46 with a concave surface on the reduction side, a positive power meniscus lens L47 with a convex surface on the enlargement side, and a concave surface on the reduction side A negative power meniscus lens L48 and a biconvex lens L49 are arranged in this order. The biconcave lens L41 and the biconvex lens L42 are cemented with each other, and the biconcave lens L44 and the biconvex lens L45 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L42 and the biconvex lens L43.

  In the second lens group 64, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z40 having a convex surface facing the reduction side, biconcave lenses Z41 and Z42, and on the enlargement side A positive power meniscus lens Z43 having a convex surface and plastic aspherical lenses Z44, Z45 having both aspherical surfaces on both sides are arranged in this order. In order to avoid interference with the light emitted from the concave mirror 32D, portions of the aspherical lenses Z44 and Z45 that do not contribute to the image formation of the projected image Pi are notched. The negative lens group having the strongest negative power among the optical lenses Z40 to Z45 constituting the second lens group 64 is a combination of a biconcave lens Z41 and a biconcave lens Z42.

  FIG. 26 is a diagram showing a spot diagram of light rays on the projection surface 40p of the screen 40 when the fourth embodiment is used. The spot diagram of FIG. 26 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 26, it can be seen that the optical aberrations are appropriately and satisfactorily corrected for the object height of 12 points.

Embodiment 5 FIG.
Next, a fifth embodiment according to the present invention will be described. FIG. 27 is a diagram illustrating a configuration of the projection optical system 30E according to the fifth embodiment. The configuration of the projection display apparatus of the fifth embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30E of FIG.

  The projection optical system 30E of the present embodiment includes a projection lens group 31E and a concave mirror 32E arranged along the optical axis AX. FIG. 27 shows a cut end face of the projection lens group 31E in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32E in the YZ plane.

  The projection lens group 31E includes a first lens group 55 having a positive power as a whole and a second lens group 65 having a negative power as a whole. The first lens group 55 includes a plurality of optical lenses L50 to L59, and includes an aperture stop 33 between the optical lenses L52 and L53. On the other hand, the second lens group 65 includes a plurality of optical lenses Z50 to Z55, and refracts incident light from the first lens group 55 with a negative power and outputs the refracted light to the concave mirror 32E.

  Both the projection lens group 31E and the concave mirror 32E have a rotationally symmetric shape. However, a part of the concave mirror 32E is cut out in order to avoid interference with a light beam traveling from the concave mirror 32E toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line.

  In the second lens group 65, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z50 and two optical lenses Z51 and Z52. C5, a positive power optical lens Z53, and aspherical lenses Z54 and Z55 are arranged in this order. The aspheric lenses Z54 and Z55 can be made of a plastic material, and the optical lenses Z50 to Z53 other than the aspheric lenses Z54 and Z55 can be made of a glass material.

  The first lens group 55 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 65 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 55 (the image surface side lens surface of the optical lens L59) and the concave mirror 32E. An intermediate image (conjugate image) MI5 is formed at the conjugate imaging position. A part of the intermediate image MI5 is formed in a region closer to the object plane than the light exit surface of the second lens group 65 (image surface side lens surface of the aspherical lens Z55), as shown in FIG. Therefore, the intermediate image MI5 is formed so as to cross the front end portion of the second lens group 65. Thereby, compared with the case where all the intermediate images are formed between the 2nd lens group 65 and the concave mirror 32E, the distance between the concave mirror 32E and the 2nd lens group 65 can be made small. Therefore, the projection optical system 30E can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31E of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 65 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32E. In the optical axis direction. F1 is the overall focal length of the projection lens group 31E, that is, the combined focal length of the first lens group 55 and the second lens group 65. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L50 to L59 and Z50 to Z53 other than aspherical lenses Z54 and Z55. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32E and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32E and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 65. In the present embodiment, the combination lens C <b> 5 including the optical lenses Z <b> 51 and Z <b> 52 is a lens group having the strongest negative power in the second lens group 65.

  By using the projection optical system 30E that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all of the optical lenses Z50 to Z55 constituting the second lens group 65 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the 2nd lens group 65 can be suppressed.

  Therefore, also in Embodiment 5, since the projection optical system 30E that satisfies the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Furthermore, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 65. Thus, the manufacturing cost can be reduced.

(Example 5)
Next, an example (hereinafter also referred to as Example 5) of the projection optical system 30E according to Embodiment 5 will be described. FIG. 28 is a diagram showing optical surfaces s0 to s2, se3 to se32 of the components of the projection optical system 30E. Optical surfaces se3 to se32 represent lens surfaces constituting the projection lens group 31E. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32E is se33.

  FIG. 29 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, se3 to se33, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30E. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the case of the present embodiment, the lens surfaces se29 to se32 constituting the aspheric lenses Z54 and Z55 and the reflection curved surface se33 of the concave mirror 32E each have an aspheric shape. The shapes of the lens surfaces se29 to se32 and the reflection curved surface se33 are determined according to the aspheric polynomial (8).

Figure 30 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface se29~se32 and reflection curved surface se33 of this embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 8.16 mm. The projected image size D is 60 inches, and the F number of the projection optical system 30E is F2.5. In this embodiment, the projected image size D is relatively small and the offset amount δ is large.

  As shown in FIG. 28, in the first lens group 55, from the object plane side (reduction side) to the image plane side (enlargement side), a biconvex lens L50, a biconcave lens L51, a biconvex lens L52, and a biconvex lens. L53, a biconcave lens L54, a biconvex lens L55, a biconcave lens L56, a biconvex lens L57, a negative power meniscus lens L58 with a concave surface on the reduction side, and a positive power meniscus lens with a convex surface on the reduction side L59 are arranged in this order. The biconcave lens L51 and the biconvex lens L52 are cemented with each other, and the biconvex lens L55 and the biconcave lens L56 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L52 and the biconvex lens L53.

  In the second lens group 65, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z50 having a convex surface on the reduction side, biconcave lenses Z51 and Z52, and on the enlargement side A positive-power meniscus lens Z53 having a convex surface and plastic aspherical lenses Z54 and Z55 whose both surfaces are aspherical are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z50 to Z55 constituting the second lens group 65 is a combination of a biconcave lens Z51 and a biconcave lens Z52. In this embodiment, interference between the light emitted from the concave mirror 32E and the projection lens group 31E does not occur, but an ineffective portion where the light of the lenses constituting the projection lens group 31E does not pass can be cut out.

  FIG. 31 is a diagram showing a spot diagram of light rays on the projection surface 40p of the screen 40 when the fifth embodiment is used. The spot diagram of FIG. 31 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 31, it can be seen that the optical aberrations are corrected appropriately and satisfactorily with respect to the object height of 12 points.

Embodiment 6 FIG.
Next, a sixth embodiment according to the present invention will be described. FIG. 32 is a diagram showing the configuration of the projection optical system 30F of the sixth embodiment. The configuration of the projection display apparatus of the sixth embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30F of FIG.

  The projection optical system 30F of the present embodiment includes a projection lens group 31F and a concave mirror 32F arranged along the optical axis AX. FIG. 32 shows a cut end surface of the projection lens group 31F in the YZ plane including the optical axis AX and a cross section of the concave mirror 32F in the YZ plane.

  The projection lens group 31F includes a first lens group 56 having a positive power as a whole and a second lens group 66 having a negative power as a whole. The first lens group 56 includes a plurality of optical lenses L60 to L69, and includes an aperture stop 33 between the optical lenses L62 and L63. On the other hand, the second lens group 66 includes a plurality of optical lenses Z60 to Z65. The second lens group 66 refracts incident light from the first lens group 55 with negative power and emits the light to the concave mirror 32F.

  In the second lens group 66, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z60 and two optical lenses Z61 and Z62. C6, a positive power optical lens Z63, and aspherical lenses Z64 and Z65 are arranged in this order. The aspheric lenses Z64 and Z65 can be made of a plastic material, and the optical lenses Z60 to Z63 other than the aspheric lenses Z64 and Z65 can be made of a glass material.

  Both the projection lens group 31F and the concave mirror 32F have a rotationally symmetric shape. However, a part of the concave mirror 32F is notched in order to avoid interference with a light beam directed from the concave mirror 32F toward the screen 40, and the not-effective part thus cut out is indicated by a dotted line. In addition, a part of the optical lens Z65 constituting the second lens group 66 is also cut out to avoid interference with the light beam from the concave mirror 32F toward the screen 40, and the cut off ineffective portion is a dotted line. It is shown in

  The first lens group 56 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 66 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 56 (image surface side lens surface of the optical lens L69) and the concave mirror 32F. An intermediate image (conjugate image) MI6 is formed at the conjugate imaging position. A part of the intermediate image MI6 is formed in a region closer to the object plane than the light exit surface of the second lens group 66 (image surface side lens surface of the aspherical lens Z65), as shown in FIG. Therefore, the intermediate image MI6 is formed so as to cross the front end portion of the second lens group 66. Thereby, the distance between the concave mirror 32F and the second lens group 66 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 66 and the concave mirror 32F. Therefore, the projection optical system 30F can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31F of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 66 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32F. In the optical axis direction. F1 is the overall focal length of the projection lens group 31F, that is, the combined focal length of the first lens group 56 and the second lens group 66. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L60 to L69, Z60 to Z63 other than aspherical lenses Z64 and Z65. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32F and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32F and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 66. In the present embodiment, the combination lens C <b> 6 including the optical lenses Z <b> 61 and Z <b> 62 is a lens group having the strongest negative power in the second lens group 66.

  By using the projection optical system 30F that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all the optical lenses Z60 to Z65 constituting the second lens group 66 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the 2nd lens group 66 can be suppressed.

  Therefore, also in Embodiment 6, since the projection optical system 30F that satisfies the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Furthermore, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 66. Thus, the manufacturing cost can be reduced.

(Example 6)
Next, an example (hereinafter also referred to as Example 6) of the projection optical system 30F according to Embodiment 6 will be described. FIG. 33 is a diagram showing optical surfaces s0 to s2, sf3 to sf33 of the components of the projection optical system 30F. Optical surfaces sf3 to sf33 represent lens surfaces constituting the projection lens group 31F. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32F is sf34.

  FIG. 34 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sf3 to sf34, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30F. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the case of the present embodiment, the lens surfaces sf30 to sf33 constituting the aspheric lenses Z64 and Z65 and the reflection curved surface sf34 of the concave mirror 32F each have an aspheric shape. The shapes of the lens surfaces sf30 to sf33 and the reflection curved surface sf34 are determined according to the above-mentioned aspheric polynomial (8).

Figure 35 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface sf30~sf33 and reflection curved surface sf34 of the present embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 5.71 mm. The projected image size D is 100 inches, and the F number of the projection optical system 30F is F2.5. In this embodiment, the projection image size D is medium and the offset amount δ is medium.

  As shown in FIG. 33, in the first lens group 56, biconvex lenses L60, L61, L62, and L63, and biconcave lenses L64 and L65 are arranged from the object plane side (reduction side) to the image plane side (enlargement side). The biconvex lenses L66 and L67, the negative power meniscus lens L68 with the concave surface facing the reduction side, and the positive power meniscus lens L69 with the convex surface facing the reduction side are arranged in this order. The biconcave lens L63 and the biconvex lens L64 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L62 and the biconvex lens L63.

  In the second lens group 66, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z60 with a convex surface facing the reduction side, biconcave lenses Z61 and Z62, and on the enlargement side A positive-power meniscus lens Z63 having a convex surface and plastic aspherical lenses Z64 and Z65 whose both surfaces are aspherical are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z60 to Z65 constituting the second lens group 66 is a combination of a biconcave lens Z61 and a biconcave lens Z62. In order to avoid interference with the light emitted from the concave mirror 32F, a portion of the aspheric lens Z65 that does not contribute to the formation of the projected image Pi is cut out.

  FIG. 36 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the sixth embodiment is used. The spot diagram of FIG. 36 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 36, it can be seen that the optical aberrations are appropriately and satisfactorily corrected for the object height of 12 points.

Embodiment 7 FIG.
Next, a seventh embodiment according to the present invention will be described. FIG. 37 is a diagram showing a configuration of the projection optical system 30G of the seventh embodiment. The configuration of the projection display apparatus of the seventh embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30G of FIG.

  The projection optical system 30G of the present embodiment includes a projection lens group 31G and a concave mirror 32G arranged along the optical axis AX. FIG. 37 shows a cut end surface of the projection lens group 31G in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32G in the YZ plane.

  The projection lens group 31G includes a first lens group 57 having a positive power as a whole and a second lens group 67 having a negative power as a whole. The first lens group 57 includes a plurality of optical lenses L70 to L79, and includes an aperture stop 33 between the optical lenses L72 and L73. On the other hand, the second lens group 67 is composed of a plurality of optical lenses Z70 to Z75, and refracts incident light from the first lens group 57 with negative power and outputs it to the concave mirror 32G.

  Both the projection lens group 31G and the concave mirror 32G have a rotationally symmetric shape. However, a part of the concave mirror 32G is cut out in order to avoid interference with a light beam traveling from the concave mirror 32G toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line.

  In the second lens group 67, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z70 and two optical lenses Z71 and Z72. C7, a positive power optical lens Z73, and aspherical lenses Z74 and Z75 are arranged in this order. The aspherical lenses Z74 and Z75 can be made of a plastic material, and the optical lenses Z70 to Z73 other than the aspherical lenses Z74 and Z75 can be made of a glass material.

  The first lens group 57 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 67 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emitting surface of the first lens group 57 (image surface side lens surface of the optical lens L79) and the concave mirror 32G. An intermediate image (conjugate image) MI7 is formed at the conjugate imaging position. A part of this intermediate image MI7 is formed in a region closer to the object plane than the light exit surface of the second lens group 67 (image surface side lens surface of the aspherical lens Z75), as shown in FIG. Therefore, the intermediate image MI7 is formed so as to cross the front end portion of the second lens group 67. Thereby, the distance between the concave mirror 32G and the second lens group 67 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 67 and the concave mirror 32G. Therefore, the projection optical system 30G can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31G of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 67 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32G. In the optical axis direction. F1 is the overall focal length of the projection lens group 31G, that is, the combined focal length of the first lens group 57 and the second lens group 67. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L70 to L79 and Z70 to Z73 other than aspherical lenses Z74 and Z75. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32G and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32G and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 67. In the present embodiment, the combination lens C 7 including the optical lenses Z 71 and Z 72 is a lens group having the strongest negative power in the second lens group 67.

  By using the projection optical system 30G that satisfies the conditional expressions (2) to (4), the slow ratio La / D can be set within a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all the optical lenses Z70 to Z75 constituting the second lens group 67 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the second lens group 67 can be suppressed.

  Therefore, also in Embodiment 7, since the projection optical system 30G satisfying the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Further, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 67. Thus, the manufacturing cost can be reduced.

(Example 7)
Next, an example (hereinafter also referred to as Example 7) of the projection optical system 30G according to Embodiment 7 will be described. FIG. 38 is a diagram showing optical surfaces s0 to s2, sg3 to sg33 of the components of the projection optical system 30G. Optical surfaces sg3 to sg33 represent lens surfaces constituting the projection lens group 31G. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32G is sg34.

  39 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sg3 to sg34, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30G. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the present embodiment, the lens surfaces sg30 to sg33 constituting the aspheric lenses Z74 and Z75 and the reflection curved surface sg34 of the concave mirror 32G each have an aspheric shape. The shapes of the lens surfaces sg30 to sg33 and the reflection curved surface sg34 are determined according to the above-mentioned aspheric polynomial (8).

Figure 40 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface sg30~sg33 and reflection curved surface sg34 of this embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 6.53 mm. The projection image size D is 150 inches, and the F number of the projection optical system 30G is F2.5. In this embodiment, the projected image size D is relatively large and the offset amount δ is also relatively large.

  As shown in FIG. 38, in the first lens group 57, from the object plane side (reduction side) to the image plane side (enlargement side), biconvex lenses L70 and L71 and positive power with the convex surface facing the reduction side. Meniscus lens L72, biconvex lens L73, biconcave lenses L74 and L75, biconvex lenses L76 and L77, negative power meniscus lens L78 with a concave surface on the reduction side, and positive power meniscus with a convex surface on the reduction side Lenses L79 are arranged in this order. The biconcave lens L73 and the biconvex lens L74 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L72 and the biconvex lens L73.

  In the second lens group 67, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z70 having a convex surface on the reduction side, biconcave lenses Z71 and Z72, and on the enlargement side A positive-power meniscus lens Z73 having a convex surface and plastic aspherical lenses Z74 and Z75 whose both surfaces are aspherical are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z70 to Z75 constituting the second lens group 67 is a combination of a biconcave lens Z71 and a biconcave lens Z72.

  FIG. 41 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the seventh embodiment is used. The spot diagram of FIG. 41 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 41, it can be seen that various optical aberrations are corrected appropriately and satisfactorily for the object height of 12 points.

Embodiment 8 FIG.
Next, an eighth embodiment according to the present invention will be described. FIG. 42 is a diagram illustrating a configuration of the projection optical system 30H according to the eighth embodiment. The configuration of the projection display apparatus of the eighth embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30H of FIG.

  The projection optical system 30H according to the present embodiment includes a projection lens group 31H and a concave mirror 32H arranged along the optical axis AX. FIG. 42 shows a cut end surface of the projection lens group 31H in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32H in the YZ plane.

  The projection lens group 31H includes a first lens group 58 having a positive power as a whole and a second lens group 68 having a negative power as a whole. The first lens group 58 includes a plurality of optical lenses L80 to L89, and includes an aperture stop 33 between the optical lenses L82 and L83. On the other hand, the second lens group 68 includes a plurality of optical lenses Z80 to Z85, and refracts incident light from the first lens group 58 with negative power and emits the light to the concave mirror 32H.

  In the second lens group 68, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z80 and two optical lenses Z81 and Z82. C8, a positive power optical lens Z83, and aspherical lenses Z84 and Z85 are arranged in this order. The aspherical lenses Z84 and Z85 can be made of a plastic material, and the optical lenses Z80 to Z83 other than the aspherical lenses Z84 and Z85 can be made of a glass material.

  Both the projection lens group 31H and the concave mirror 32H have a rotationally symmetric shape. However, a part of the concave mirror 32H is cut out in order to avoid interference with a light beam traveling from the concave mirror 32H toward the screen 40, and the cut-out ineffective portion is indicated by a dotted line. Further, part of the optical lenses Z84 and Z85 constituting the second lens group 68 is also cut out to avoid interference with the light beam from the concave mirror 32A toward the screen 40, and the cut out ineffective portion. Is indicated by a dotted line.

  The first lens group 58 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 68 is optically connected to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 58 (image surface side lens surface of the optical lens L89) and the concave mirror 32H. An intermediate image (conjugate image) MI8 is formed at the conjugate imaging position. A part of the intermediate image MI8 is formed in a region closer to the object plane than the light exit surface of the second lens group 68 (image surface side lens surface of the aspherical lens Z85), as shown in FIG. Therefore, the intermediate image MI8 is formed so as to cross the front end portion of the second lens group 68. Thereby, the distance between the concave mirror 32H and the second lens group 68 can be reduced as compared with the case where all of the intermediate image is formed between the second lens group 68 and the concave mirror 32H. Therefore, the projection optical system 30H can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31H of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 68 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32H. In the optical axis direction. F1 is the overall focal length of the projection lens group 31H, that is, the combined focal length of the first lens group 58 and the second lens group 68. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of the lens surface, surface interval, etc.) of the optical lenses L80 to L89 and Z80 to Z83 other than the aspherical lenses Z84 and Z85. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32H and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32H and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 68. In the present embodiment, the combination lens C8 including the optical lenses Z81 and Z82 is the lens group having the strongest negative power in the second lens group 68.

  By using the projection optical system 30H that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set to a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all the optical lenses Z80 to Z85 constituting the second lens group 68 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the second lens group 68 can be suppressed.

  Therefore, also in Embodiment 8, since the projection optical system 30H that satisfies the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Further, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 68. Thus, the manufacturing cost can be reduced.

(Example 8)
Next, an example (hereinafter also referred to as Example 8) of the projection optical system 30H according to Embodiment 8 will be described. FIG. 43 is a diagram showing optical surfaces s0 to s2, sh3 to sh33 of the components of the projection optical system 30H. The optical surfaces sh3 to sh33 represent lens surfaces constituting the projection lens group 31H. In addition, although not shown in figure, the code | symbol of the reflective curved surface of the concave mirror 32H is sh34.

  44 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, sh3 to sh34, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30H. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the present embodiment, the lens surfaces sh30 to sh33 constituting the aspheric lenses Z84 and Z85 and the reflection curved surface sh34 of the concave mirror 32H each have an aspheric shape. The shapes of these lens surfaces sh30 to sh33 and the reflection curved surface sh34 are determined according to the above aspheric polynomial (8).

Figure 45 is a diagram showing the data values of the conic coefficient k and the aspherical coefficients _{A i} defining the aspherical shape of the lens surface sh30~sh33 and reflection curved surface sh34 of this embodiment in a tabular format. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulator 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulator 20 is 4.9 mm. The projection image size D is 200 inches, and the F number of the projection optical system 30H is F2.5. In this embodiment, the projected image size D is larger and the offset amount δ is relatively small.

  As shown in FIG. 43, in the first lens group 58, biconvex lenses L80, L81, L82, and L83, and biconcave lenses L84 and L85 are arranged from the object plane side (reduction side) to the image plane side (enlargement side). The biconvex lenses L86 and L87, the negative power meniscus lens L88 having a concave surface facing the reduction side, and the positive power meniscus lens L89 having a convex surface facing the reduction side are arranged in this order. The biconcave lens L83 and the biconvex lens L84 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L82 and the biconvex lens L83.

  In the second lens group 68, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z80 with a convex surface facing the reduction side, biconcave lenses Z81 and Z82, and on the enlargement side A positive-power meniscus lens Z83 having a convex surface and plastic aspherical lenses Z84 and Z85 having both aspherical surfaces on both sides are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z80 to Z85 constituting the second lens group 68 is a combination of a biconcave lens Z81 and a biconcave lens Z82. In order to avoid interference with the light emitted from the concave mirror 32H, portions of the aspherical lenses Z84 and Z85 that do not contribute to the image formation of the projected image Pi are notched.

  FIG. 46 is a diagram illustrating a spot diagram of light rays on the projection surface 40p of the screen 40 when the eighth embodiment is used. The spot diagram of FIG. 46 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 46, it can be seen that the optical aberrations are appropriately and satisfactorily corrected for the object height of 12 points.

Embodiment 9 FIG.
Next, a ninth embodiment according to the present invention will be described. FIG. 47 is a diagram showing a configuration of the projection optical system 30I of the ninth embodiment. The configuration of the projection display apparatus of the ninth embodiment is the same as that of the projection display apparatus 1 of the first embodiment except for the projection optical system 30I of FIG.

  The projection optical system 30I according to the present embodiment includes a projection lens group 31I and a concave mirror 32I arranged along the optical axis AX. FIG. 47 shows a cut end face of the projection lens group 31I in the YZ plane including the optical axis AX, and a cross section of the concave mirror 32I in the YZ plane.

  The projection lens group 31I includes a first lens group 59 having a positive power as a whole and a second lens group 69 having a negative power as a whole. The first lens group 59 includes a plurality of optical lenses L90 to L99, and includes an aperture stop 33 between the optical lenses L92 and L93. On the other hand, the second lens group 69 includes a plurality of optical lenses Z90 to Z95, refracts incident light from the first lens group 59 with negative power, and emits the light to the concave mirror 32I. Both the projection lens group 31I and the concave mirror 32I have a rotationally symmetric shape.

  In the second lens group 69, from the object plane side (reduction side) to the image plane side (enlargement side), a negative power combination lens composed of a positive power optical lens Z90 and two optical lenses Z91 and Z92. C9, a positive power optical lens Z93, and aspherical lenses Z94 and Z95 are arranged in this order. The aspherical lenses Z94 and Z95 can be made of a plastic material, and the optical lenses Z90 to Z93 other than the aspherical lenses Z94 and Z95 can be made of a glass material.

  The first lens group 59 can receive the light beam emitted from the spatial light modulator 20 and refract the light beam with a positive power to reduce the spread angle of the light beam. The second lens group 69 is optically coupled to the light modulation surface of the spatial light modulation element 20 in a region between the light emission surface of the first lens group 59 (the image surface side lens surface of the optical lens L99) and the concave mirror 32I. An intermediate image (conjugate image) MI9 is formed at the conjugate imaging position. A part of the intermediate image MI9 is formed in a region closer to the object plane than the light exit surface of the second lens group 69 (image surface side lens surface of the aspherical lens Z95), as shown in FIG. Therefore, the intermediate image MI9 is formed so as to cross the front end portion of the second lens group 69. Accordingly, it is possible to reduce the distance between the concave mirror 32I and the second lens group 69 as compared with the case where all of the intermediate image is formed between the second lens group 69 and the concave mirror 32I. . Therefore, the projection optical system 30I can be downsized.

  For the same reason as in the first embodiment, the projection lens group 31I of the present embodiment is also configured to satisfy the conditional expressions (2) to (4).

  In the present embodiment, Lb in the conditional expression (2) is between the front end of the second lens group 69 (the surface vertex of the lens surface closest to the image plane) and the surface vertex of the reflection curved surface of the concave mirror 32I. In the optical axis direction. F1 is the overall focal length of the projection lens group 31I, that is, the combined focal length of the first lens group 59 and the second lens group 69. However, the focal length f1 is calculated based on optical parameters (refractive index, radius of curvature of lens surface, surface interval, etc.) of optical lenses L90 to L99 and Z90 to Z93 other than aspherical lenses Z94 and Z95. .

  In the conditional expression (3), θmax is the maximum value among the angles θ formed by the principal ray incident on the concave mirror 32I and the optical axis AX, and φmax is the principal ray emitted from the concave mirror 32I and the optical axis AX. It is the maximum value in the angle φ formed by. In the conditional expression (4), f2 is a focal length of a single lens or a combination lens having the strongest negative power among the optical lenses included in the second lens group 69. In the present embodiment, the combination lens C9 including the optical lenses Z91 and Z92 is a lens group having the strongest negative power in the second lens group 69.

  By using the projection optical system 30I that satisfies the conditional expressions (2) to (4), the slow ratio La / D is set to a suitable range (0.14 or more and 0) defined by the conditional expression (1). .. (range of 20 or less).

  For the same reason as in the first embodiment, all of the optical lenses Z90 to Z95 constituting the second lens group 69 of the present embodiment have the conditional expressions (5) to (7) and nd ≦ 1. It is preferable that the optical material satisfy any one of 63. Thereby, the manufacturing cost of the second lens group 69 can be suppressed.

  Therefore, also in Embodiment 9, since the projection optical system 30I that satisfies the conditional expressions (2) to (4) is used, a small projection in which the slow ratio La / D is small and various optical aberrations are well corrected. A mold display device 1 can be provided. Furthermore, an optical material having a combination of the refractive index nd and the Abbe number νd within the range satisfying any of the above (5) to (7) and nd ≦ 1.63 is used as the constituent material of the second lens group 69. Thus, the manufacturing cost can be reduced.

Example 9
Next, an example (hereinafter also referred to as Example 9) of the projection optical system 30I according to Embodiment 9 will be described. FIG. 48 is a diagram showing optical surfaces s0 to s2, si3 to si33 of components of the projection optical system 30H. Optical surfaces si3 to si33 represent lens surfaces constituting the projection lens group 31I. Although not shown, the sign of the reflection curved surface of the concave mirror 32H is si34.

  49 shows the radius of curvature (unit: millimeter) of the optical surfaces s0 to s2, si3 to si34, the distance between adjacent optical surfaces, that is, the surface interval (unit: millimeter), and the projection optical system 30I. It is a figure which shows the refractive index nd and Abbe number (nu) d of a component in a tabular form. In the case of the present embodiment, the lens surfaces si30 to si33 constituting the aspheric lenses Z94 and Z95 and the reflection curved surface si34 of the concave mirror 32I each have an aspheric shape. The shapes of the lens surfaces si30 to si33 and the reflection curved surface si34 are determined according to the aspheric polynomial (8).

FIG. 50 is a diagram showing, in a tabular form, data values of the conic coefficient k and the aspheric coefficient A _i that define the aspheric shapes of the lens surfaces si30 to si33 and the reflection curved surface si34 of the present embodiment. Here, since N = 12, the values of the aspheric coefficient A _i of the 13th order or higher are all zero.

  In the present embodiment, the size of the light modulation unit 21 of the spatial light modulation element 20 is 14.55152 mm × 8.1648 mm, and the offset amount δ of the spatial light modulation element 20 is 8.16 mm. The projected image size D is 200 inches, and the F number of the projection optical system 30I is F2.5. In this embodiment, the projected image size D is larger and the offset amount δ is relatively large.

  As shown in FIG. 48, in the first lens group 59, biconvex lenses L90, L91, L92, L93 and biconcave lenses L94, L95 from the object plane side (reduction side) to the image plane side (enlargement side) The biconvex lenses L96 and L97, the negative power meniscus lens L98 with the concave surface facing the reduction side, and the positive power meniscus lens L99 with the convex surface facing the reduction side are arranged in this order. The biconcave lens L93 and the biconvex lens L94 are cemented with each other. An aperture stop 33 is provided between the biconvex lens L92 and the biconvex lens L93.

  In the second lens group 69, from the object plane side (reduction side) to the image plane side (enlargement side), a positive power meniscus lens Z90 having a convex surface facing the reduction side, biconcave lenses Z91 and Z92, and on the enlargement side A positive power meniscus lens Z93 having a convex surface and plastic aspherical lenses Z94 and Z95 having both aspherical surfaces on both sides are arranged in this order. The negative lens group having the strongest negative power among the optical lenses Z90 to Z95 constituting the second lens group 69 is a combination of biconcave lenses Z91 and Z92.

  FIG. 51 is a diagram showing a spot diagram of light rays on the projection surface 40p of the screen 40 when the ninth embodiment is used. The spot diagram of FIG. 51 was obtained under the same conditions as those used in obtaining the spot diagram of FIG. Further, the meaning of the numerical value shown on the left side of each spot diagram is the same as the meaning of the numerical value shown on the left side of the spot diagram of FIG. As shown in FIG. 51, it can be seen that the optical aberrations are appropriately and satisfactorily corrected for the object height of 12 points.

(About Examples 1 to 9)
For Examples 1 to 9, the values of La / D, Lb / f1, φmax / θmax and f2 / f1 in the conditional expressions (1) to (4) are shown in the table of FIG. As shown in FIG. 52, it is understood that conditional expressions (1) to (4) are satisfied for each example. In addition, the second lens groups 61 to 69 of Examples 1 to 9 are all within the range (hatching range in FIG. 7) that satisfies any of the conditional expressions (5) to (7) and nd ≦ 1.63. And an optical material having a refractive index nd and an Abbe number νd.

  Although various embodiments according to the present invention have been described above with reference to the drawings, these are examples of the present invention, and various forms other than the above can be adopted. For example, the combination lenses C1 to C9 are employed as suitable lenses having the strongest negative power in the second lens groups 61 to 69 of Embodiments 1 to 9, but the present invention is not limited to this. Instead of the combination lenses C1 to C9, a single lens having optical performance equivalent to these can be employed.

  DESCRIPTION OF SYMBOLS 1 Projection type display apparatus, 10 Illumination mechanism, 11 Lamp light source, 12 Control part, 13 Drive part, 14 Light uniformizing element, 15 Color wheel, 16 Light guide optical system, 17 Reflection mirror, 18 Internal total reflection prism, 20 Space Light modulation element, 21 Light modulation part, 22 Cover glass, 30, 30A-30I Projection optical system, 31, 31A-31I Projection lens group, 32, 32A-32I Concave mirror, 33 Aperture stop, 40 Screen, 40p Projection surface 51-59 1st lens group, 61-69 2nd lens group.

Claims (19)

A projection optical system that receives modulated light emitted from a spatial light modulation element, enlarges and projects an optical image represented by the modulated light on a projection surface, and forms a projection image on the projection surface;
A first lens group that refracts the modulated light with positive power;
A second lens group that refracts incident light from the first lens group with a negative power;
A concave mirror that faces the light exit surface of the second lens group and reflects the incident light from the second lens group in the direction of the projection surface to form an image.
The distance between the light exit surface of the second lens group and the surface vertex of the concave mirror is Lb, the combined focal length of the first lens group and the second lens group is f1, and the second lens group. And the maximum value of the angle formed between the common optical axis of the concave mirror and the chief ray emitted from the concave mirror is φmax, and the maximum value of the angle between the chief ray incident on the concave mirror and the optical axis is θmax. When the focal length of the single lens or combination lens having the strongest negative power among the optical lenses included in the second lens group is f2,
4.20 ≦ Lb / f1 ≦ 6.25,
1.85 ≦ φmax / θmax ≦ 2.20, and
−1.55 ≦ f2 / f1 ≦ −1.00,
A projection optical system characterized by the following conditional expression: The projection optical system according to claim 1,
The second lens group forms an intermediate image at a position optically conjugate with the light modulation surface of the spatial light modulation element in a region between the concave mirror and the first lens group;
A part of the intermediate image is formed on the first lens group side with respect to the light exit surface of the second lens group. The projection optical system according to claim 1 or 2,
The second lens group includes first and second optical lenses having positive power,
The projection optical system according to claim 1, wherein the first and second optical lenses are arranged at positions sandwiching both lens surfaces of the single lens or the combination lens having the focal length f2.   4. The projection optical system according to claim 1, wherein the second lens group is disposed closer to the image plane than the single lens or the combination lens having the focal length f <b> 2. The projection optical system further comprising at least one aspheric lens.   5. The projection optical system according to claim 4, wherein the combined focal length f <b> 1 is a value calculated based on an optical lens other than the at least one aspheric lens among the optical lenses included in the second lens group. A projection optical system characterized by   6. The projection optical system according to claim 4, wherein the at least one aspheric lens is made of a plastic material. A projection optical system according to any one of claims 4 to 7,
The lens surface of the aspheric lens has a rotationally symmetric aspheric shape with respect to the optical axis,
The amount of sag in the optical axis direction of the rotationally symmetric aspheric surface is defined by a polynomial having a height from the optical axis as a variable,
The projection optical system according to claim 1, wherein the first-order coefficient of the polynomial has a non-zero value.   8. The projection optical system according to claim 1, wherein the combination lens having the focal length f2 includes an aspheric lens.   9. The projection optical system according to claim 8, wherein the aspheric lens included in the combination lens is made of a glass material.   8. The projection optical system according to claim 4, wherein the second lens group includes the single lens or the combination lens having the focal length f2 and the at least one aspheric lens. A projection optical system further comprising an intermediate aspherical lens disposed between the two. A projection optical system according to any one of claims 1 to 10,
When the refractive index for the d-line of the lens included in the second lens group is nd, and the Abbe number for the d-line of the lens included in the second lens group is νd,
The second lens group includes:
νd ≦ −50nd + 120 (1.8 <nd),
νd ≦ −149.25nd + 298.51 (1.7 <nd ≦ 1.8), and
νd ≦ −212.77nd + 406.38 (1.63 <nd ≦ 1.7),
The projection optical system is formed of an optical material that satisfies any of the following three conditional expressions and nd ≦ 1.63. 12. The projection optical system according to claim 1, wherein a distance in a normal direction of the projection surface between a surface vertex of the concave mirror and the projection surface is defined as La. When the dimension of the projected image is D,
0.14 ≦ La / D ≦ 0.20,
A projection optical system characterized by the following conditional expression: An illumination device including a light source;
A spatial light modulation element that spatially modulates light emitted from the illumination device according to an image signal;
A projection optical system that receives the modulated light emitted from the spatial light modulation element, enlarges and projects an optical image represented by the modulated light on the projection surface, and forms a projection image on the projection surface;
The projection optical system is
A first lens group that refracts the modulated light with positive power;
A second lens group that refracts incident light from the first lens group with a negative power;
A concave mirror that faces the light exit surface of the second lens group and reflects the incident light from the second lens group in the direction of the projection surface to form an image.
The distance between the light exit surface of the second lens group and the surface vertex of the concave mirror is Lb, the combined focal length of the first lens group and the second lens group is f1, and the second lens group. And the maximum value of the angle formed between the common optical axis of the concave mirror and the chief ray emitted from the concave mirror is φmax, and the maximum value of the angle between the chief ray incident on the concave mirror and the optical axis is θmax. When the focal length of the single lens or combination lens having the strongest negative power among the optical lenses included in the second lens group is f2,
4.20 ≦ Lb / f1 ≦ 6.25,
1.85 ≦ φmax / θmax ≦ 2.20, and
−1.55 ≦ f2 / f1 ≦ −1.00,
A projection display device characterized by satisfying the following conditional expression: The projection display device according to claim 13,
The second lens group forms an intermediate image at a position optically conjugate with the light modulation surface of the spatial light modulation element between the concave mirror and the first lens group,
A part of the intermediate image is formed on the first lens group side with respect to the light exit surface of the second lens group. The projection display device according to claim 13 or 14,
The second lens group includes first and second optical lenses having positive power,
The projection display device, wherein the first and second optical lenses are arranged at positions sandwiching both lens surfaces of the single lens or the combination lens having the focal length f2.   16. The projection display device according to claim 13, wherein the second lens group is disposed closer to the image plane than the single lens or the combination lens having the focal length f <b> 2. A projection display device comprising at least one aspherical lens. The projection display device according to claim 16, wherein
The lens surface of the aspheric lens has a rotationally symmetric aspheric shape with respect to the optical axis,
The amount of sag in the optical axis direction of the rotationally symmetric aspheric surface is defined by a polynomial having a height from the optical axis as a variable,
The projection type display apparatus, wherein the first-order coefficient of the polynomial has a non-zero value.   18. The projection display device according to claim 13, wherein the combination lens having the focal length f <b> 2 includes an aspherical lens. The projection display device according to any one of claims 13 to 18,
When the refractive index for the d-line of the lens included in the second lens group is nd, and the Abbe number for the d-line of the lens included in the second lens group is νd,
The second lens group includes:
νd ≦ −50nd + 120 (1.8 <nd),
νd ≦ −149.25nd + 298.51 (1.7 <nd ≦ 1.8), and
νd ≦ −212.77nd + 406.38 (1.63 <nd ≦ 1.7),
The projection display device is formed of an optical material that satisfies any one of the following three conditional expressions and nd ≦ 1.63.

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