Attachment optical system and projection display system

Abstract

To provide an attachment optical system that can allow projection light directed to a screen to reach the extension of an optical axis of a projection optical system of a projection display device.SOLUTION: An attachment optical system 10A is removably attached to an enlargement side of a projection optical system 3 and projects emitted projection light on an imaging surface different from an enlargement side imaging surface of the projection optical system. The attachment optical system has an optical element 21 including a second optical axis M arranged on the extension of a first axis N of the projection optical system. The optical element comprises: an incident surface 41 that is arranged on the second optical axis; a first reflection surface 42 that reflects light emitted from the incident surface; a second reflection surface 43 that reflects the light reflected on the first reflection surface; and an emission surface 44 that transmits the light reflected on the second reflection surface. The first reflection surface and the emission surface are continuous in an on-axis area in which light passes through the second optical axis and the first optical axis. An imaging surface of the attachment optical system is substantially parallel to a reduction side imaging surface on which an optical modulator included in the projection display device forms a projection image.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an attachment optical system and a projection display system. [Background technology]

[0002] An attachment optical system that is detachably attached to the projection optical system of a projector is described in Patent Document 1. The attachment optical system in the document includes a front group consisting of two reflecting surfaces and two transmitting surfaces that are rotationally symmetric about a central axis, and a rear group that is rotationally symmetric about the central axis and has positive power. The front group is a single optical element made of a transparent medium. In the order of light rays traveling, the front group includes a first transmitting surface having positive power that enters the front group from a distant position, a first reflecting surface having positive power that is disposed on the rear group side with the first transmitting surface sandwiched between the first transmitting surface and the central axis, a second reflecting surface that is disposed on the same side as the first reflecting surface and is disposed farther from the rear group than the first reflecting surface, and a second transmitting surface having negative power that is disposed closest to the rear group.

[0003] The attachment optical system is attached to the projector with its central axis coinciding with the optical axis of the projection optical system. When the attachment optical system is attached to the projector, the first transmitting surface is located on an extension of the optical axis of the projection optical system. The first reflecting surface and the second reflecting surface are located on one side of the optical axis of the projection optical system. The second transmitting surface is located on the other side of the first reflecting surface and the second reflecting surface across the optical axis of the projection optical system, and is spaced apart from the extension of the optical axis of the projection optical system. Therefore, in this document, the projection light emitted from the projector and directed toward the screen via the attachment optical system is emitted in a direction that does not overlap with the extension of the optical axis of the projection optical system of the projector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-257360 A Summary of the Invention [Problem to be solved by the invention]

[0005] When an attachment optical system is attached to the projection optical system of a projector, there is a demand for the projection light traveling toward a screen via the attachment optical system to reach an extension of the optical axis of the projection optical system of the projector. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an attachment optical system that is detachably attached to the enlarged side of a projection optical system provided in a projection display device and projects projection light emitted from the projection optical system onto an image forming surface other than the enlarged side image forming surface of the projection optical system, the attachment optical system has an optical element with a second optical axis arranged on an extension of a first optical axis of the projection optical system, the optical element has an incident surface arranged on the second optical axis, a first reflecting surface that reflects light emitted from the incident surface, a second reflecting surface that reflects light reflected by the first reflecting surface, and an exit surface that transmits light reflected by the second reflecting surface, the first reflecting surface and the exit surface are continuous within an on-axis region where light passes through the second optical axis and the first optical axis, and the image forming surface of the attachment optical system is approximately parallel to the reduced side image forming surface of the projection optical system on which an optical modulation element provided in the projection display device forms a projected image.

[0007] A projection display system of the present invention includes the above-mentioned attachment optical system and a projection display device equipped with a projection optical system, wherein the attachment optical system is detachably attached to the projection optical system. [Brief description of the drawings]

[0008] [Figure 1] 2 is a ray diagram that illustrates a schematic view of the entire projector to which the attachment optical system of the first embodiment can be attached. [Diagram 2] FIG. 2 is a ray diagram of a projection optical system of the projector. [Diagram 3] 1 is a ray diagram illustrating a schematic view of the entire projector system of the first embodiment. [Figure 4] 2 is a ray diagram of the projection optical system of the projector and the attachment optical system of the first embodiment. [Diagram 5] FIG. 2 is a configuration diagram of an attachment optical system according to the first embodiment. [Figure 6] 5 is a diagram showing the MTF on the enlargement side of the projector system of the first embodiment. FIG. [Figure 7] FIG. 11 is a ray diagram illustrating an overall projector system according to a second embodiment. [Figure 8] 11 is a ray diagram of the projection optical system of the projector and the attachment optical system of the second embodiment. [Figure 9] FIG. 11 is a diagram showing the configuration of an attachment optical system according to a second embodiment. [Figure 10] FIG. 11 is a diagram showing the MTF on the enlargement side of the projector system of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projector system as an embodiment of a projection display system according to the present invention will be described in detail below with reference to the drawings.

[0010] Example 1 FIG. 1 is a ray diagram that shows a schematic representation of the entire projector 1 to which the attachment optical system 10A can be attached. FIG. 2 is a ray diagram of the projection optical system 3 of the projector 1. FIG. 3 is a ray diagram that shows a schematic representation of the entire projector system 100A. FIG. 4 is a ray diagram of the projection optical system 3 of the projector 1 and the attachment optical system 10A. FIG. 5 is a configuration diagram of the attachment optical system 10A. In FIGS. 1 to 5, the light beams emitted from the projector 1 and the projector system 100A are shown typically by light beams F0 to F10. The light beam F0 is a light beam that is emitted from the projector 1 and the projector system 100A and passes through the first optical axis N of the projection optical system 3. The light beam F10 is a light beam that reaches a position with the highest image height. The light beams F1 to F9 are light beams that reach intermediate positions between the light beams F0 and F10, respectively.

[0011] The projector system 100A of this example includes a projector 1, which is a projection display device, and an attachment optical system 10A that is detachably attached to the enlarged side of a projection optical system 3 included in the projector 1. In the following, first the projector 1 will be described, and then the attachment optical system 10A will be described.

[0012] 1, the projector 1 includes a light modulation element 2 that modulates light from a light source to form a projection image, a projection optical system 3 that enlarges and projects the projection image formed by the light modulation element 2, and a housing 4 that supports the projection optical system 3. The light modulation element 2 is accommodated inside the housing 4.

[0013] As shown in FIG. 2, the projection optical system 3 is a refractive optical system including a plurality of lenses. The light modulation element 2 is a liquid crystal panel. The light modulation element 2 is disposed on a reduction-side image forming surface of the projection optical system 3. The reduction-side image forming surface is perpendicular to the first optical axis N of the projection optical system 3. The light modulation element 2 forms a projected image downward with respect to the first optical axis N. As shown in FIG. 1, the first projection light B1 emitted from the projection optical system 3 spreads in the left-right direction and upward with respect to the first optical axis N. As shown in FIG. 1, when the projector 1 is used alone, a screen S1 is disposed on the enlargement-side image forming surface of the projection optical system 3. The enlargement-side image forming surface is perpendicular to the first optical axis N of the projection optical system 3.

[0014] Next, the attachment optical system 10A is attached to the tip portion of the projection optical system 3 of the projector 1, as shown in Fig. 3. In this example, in order to align the direction in which the projection light spreads before and after the attachment optical system 10A is attached to the projector 1, the projector 1 is turned upside down and then the attachment optical system 10A is attached to the projection optical system 3. Therefore, at the time when the attachment optical system 10A is attached, the light modulation element 2 of the projector 1 forms a projection image above the first optical axis N of the projection optical system 3, as shown in Fig. 4. The first projection light B1 of the projector 1 spreads in the left-right direction and below the first optical axis N.

[0015] The attachment optical system 10A includes a front group 11 and a rear group 12 (lens group). In this example, the front group 11 is made up of one optical element 21. The rear group 12 is made up of one positive lens 31 (first lens). The positive lens 31 is disposed on the projection optical system 3 side with respect to the optical element 21, and has positive power. The rear group 12 is located between the front group 11 and the projection optical system 3. A second optical axis M of the attachment optical system 10A is located on an extension of the first optical axis N of the projection optical system 3. The second optical axis M is the optical axis of the optical element 21 and also the optical axis of the positive lens 31.

[0016] The image forming surface of the projector system 100A, that is, the image forming surface of the projection optical system 3 and the attachment optical system 10A, is perpendicular to the first optical axis N. That is, the image forming surface of the attachment optical system 10A is a plane perpendicular to the first optical axis N and the second optical axis M. In this example, the image forming surface of the attachment optical system 10A is approximately parallel to the reduction-side image forming surface of the projection optical system 3 on which the light modulation element 2 of the projector 1 forms the projected image. The image forming surface of the projector system 100A is located closer to the projection optical system 3 than the enlargement-side image forming surface of the projection optical system 3. In other words, the optical system of the projector system 100A consisting of the projection optical system 3 and the attachment optical system 10A has a shorter focal length than the projection optical system 3. That is, the distance between the image forming surface of the attachment optical system 10A and the projection optical system 3 is smaller than the distance between the enlargement-side image forming surface of the projection optical system 3 and the projection optical system 3. When the projector system 100A is used, a screen S2 is placed on the imaging plane of the projection optical system 3 and the attachment optical system 10A. The second projection light B2 emitted from the attachment optical system 10A spreads in the left-right and upward directions with respect to the second optical axis M.

[0017] In the following description, for convenience, three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis. The optical axis direction along the first optical axis N of the projection optical system 3 and the second optical axis M of the attachment optical system 10A is referred to as the Z-direction. The width direction of the screen S2, which is the imaging surface of the projection optical system 3 and the attachment optical system 10A, is referred to as the X-axis direction, and the vertical direction of the screen S2 is referred to as the Y-direction. Furthermore, in the Z-direction, the side where the projection optical system 3 is located is referred to as the Z1 direction, and the side where the attachment optical system 10A is located is referred to as the Z2 direction. The lower side and downward are referred to as the Y1 direction, and the upper side and upward are referred to as the Y2 direction.

[0018] (Details of the projection optical system and attachment optical system) As shown in Fig. 4, the projection optical system 3 includes lenses L1 to L14 in that order from the reduction side to the enlargement side. A light modulation element 2 is disposed on a reduction-side image forming surface of the projection optical system 3. The light modulation element 2 forms a projected image in the Y2 direction of a first optical axis N of the projection optical system 3. A prism 5 is disposed between the light modulation element 2 and the projection optical system 3. A first projection light B1 from the projection optical system 3 is emitted in the Y1 direction from the lens L14 toward the Z2 direction.

[0019] The attachment optical system 10A includes, from the projection optical system 3 side, a rear group 12 and a front group 11. In this example, the rear group 12 is one positive lens 31 (first lens), and the front group 11 is one optical element 21. The optical element 21 is made of a transparent optical member that is partially coated with a reflective coating. The optical element 21 includes an entrance surface 41 that transmits light from the positive lens 31, a first reflecting surface 42 that reflects the light transmitted through the entrance surface 41, and a second reflecting surface 42 that reflects the light from the first reflecting surface 42. The optical element 21 has a reflecting surface 43 and an exit surface 44 that transmits light from the second reflecting surface 43. That is, the optical element 21 has an incident surface 41, a first reflecting surface 42 that reflects light emitted from the incident surface 41, a second reflecting surface 43 that reflects light reflected by the first reflecting surface 42, and an exit surface 44 that transmits light reflected from the second reflecting surface 43. The incident surface 41, the first reflecting surface 42, the second reflecting surface 43, and the exit surface 44 all have shapes that are rotationally symmetric about the second optical axis M.

[0020] The incident surface 41 is located on the second optical axis M. The incident surface 41 has a concave shape recessed in the Z2 direction. That is, the incident surface 41 has a concave shape recessed in the Z2 direction (second direction) opposite to the Z1 direction (first direction) in which the projection optical system 3 is located relative to the optical element 21 in the optical axis direction along the second optical axis M. The first reflecting surface 42 is located in the Z2 direction of the incident surface 41. Moreover, the first reflecting surface 42 is disposed in the Y1 direction with respect to the second optical axis M. The first reflecting surface 42 has a convex shape protruding in the Z1 direction. The second reflecting surface 43 is located in the Z1 direction of the first reflecting surface 42. Moreover, the second reflecting surface 43 is disposed in the Y1 direction with respect to the second optical axis M, similar to the first reflecting surface 42. The second reflecting surface 43 has a concave shape recessed in the Z1 direction. The exit surface 44 is located in the Z2 direction of the second reflecting surface 43. Moreover, the exit surface 44 is disposed in the Y2 direction with respect to the second optical axis M. The exit surface 44 has a convex shape that protrudes in the Z2 direction.

[0021] As shown in FIG. 5, the first reflecting surface 42 and the exit surface 44 are continuous in the Y direction within an axial light flux passing region (axial region) 40 of the axial light flux passing through the second optical axis M. That is, the axial light flux passing region 40 is a part of the first reflecting surface 42 and a part of the exit surface 44. The axial light flux is light passing through the first optical axis N and the second optical axis M when the attachment optical system 10A is attached to the projector 1. That is, the axial light flux passing region 40 is a region of the optical element 21 where light passes through the first optical axis N and the second optical axis M. Here, the second optical axis M is the design axis of the optical element 21. The axial light flux passing region 40 is a region that is uniquely defined when designing the optical element 21.

[0022] The first reflecting surface 42 is formed by providing a reflective coating layer on the outer surface in the Y2 direction of the optical element 21. A half-mirror coating layer is provided as the reflective coating layer on the portion of the first reflecting surface 42 that overlaps with the on-axis light beam passing area 40. The half-mirror coating layer is formed to reflect light intersecting the second optical axis M. Part of is reflected in the Z1 direction and parallel to the second optical axis M. Part of This allows the light on the second optical axis M to pass through in the Z2 direction. of Light heading in the Z2 direction Part of reaches screen S2.

[0023] Further, when viewed from the Z direction, the first reflecting surface 42, the second reflecting surface 43, and the exit surface 44 have their portions closer to the second optical axis M overlapping with the entrance surface 41. Here, in the second reflecting surface 43, the first reflecting portion 431 that does not overlap with the entrance surface 41 when viewed from the Z direction is formed by providing a reflective coating layer on the outer surface of the optical element 21 in the Z1 direction. In the second reflecting surface 43, the second reflecting portion 432 that overlaps with the entrance surface 41 when viewed from the Z direction has a reflective coating layer that reflects light heading in the Z2 direction. Part of Light passing through the lens and heading in the Z1 direction Part of The optical element 21 is formed by providing a half-mirror coating layer that reflects the reflected light. The optical element 21 is composed of two optical members, a first member 22 having a first outer surface portion 26 of a convex shape on which the surface shape of the second reflecting surface 43 is transferred to the outer surface in the Z1 direction in order to provide the half-mirror coating layer, and a second member 23 having a second outer surface portion 27 of a concave shape corresponding to the surface shape of the second reflecting surface 43 on the outer surface in the Z2 direction. The first member 22 has a reflective coating layer on a portion of the first outer surface portion 26 that does not overlap with the incident surface 41 when viewed from the Z direction, and a half-mirror coating layer on a portion that overlaps with the incident surface 41 when viewed from the Z direction. The second member 23 is joined to the first member 22 on which the reflective coating layer and the half-mirror coating layer are provided, from the Z1 direction side.

[0024] Here, inside the optical element 21, an intermediate image 20 is formed which is conjugate with the enlarged image projected onto the image forming surface. The intermediate image 20 is also conjugate with the projected image formed on the reduction-side imaging plane of the projection optical system 3. In this example, the intermediate image 20 is formed between the first reflecting surface 42 and the second reflecting surface 43.

[0025] (Lens data) The projection distance of the projection optical system 3 is 3776 mm. The projection distance of the projector system 100A consisting of the projection optical system 3 and the attachment optical system 10A is 295 mm. The numerical aperture of the optical system of the projector system 100A consisting of the projection optical system 3 and the attachment optical system 10A is 0.291. The lens data of this optical system is as follows. The surface numbers are assigned in order from the reduction side to the enlargement side. The symbols are the symbols of the liquid crystal panel, prism, lens, positive lens, first transmitting surface, first reflecting surface, second reflecting surface, second transmitting surface, and screen. The data of the surface numbers that do not correspond to the liquid crystal panel, prism, lens, positive lens, first transmitting surface, first reflecting surface, second reflecting surface, second transmitting surface, and screen are dummy data. R is the radius of curvature. D is the axial surface distance. C is the aperture radius. The units of R, D, and C are mm. The integer part of the numerical value shown for the glass material represents the refractive index multiplied by 10 to the power of 6, and the decimal part represents the Abbe number multiplied by 10 to the power of 2.

[0026] Symbol Surface number Shape RD Glass material Refraction / Reflection C 0 Sphere Infinity 0.0000 Refraction 0.0000 2 1 Sphere Infinity 1.0000 Refraction 11.8500 5 2 Sphere Infinity 31.5200 BSC7_HOYA Refraction 12.0421 3 Sphere Infinity 10.5830 Refraction 15.9895 L1 4 sphere 63.4927 6.2427 755201.2758 Refraction 18.5302 5 sphere -86.6504 0.1500 Refraction 18.4984 L2 6 sphere 113.0626 8.0000 620410.6032 Refraction 17.7500 7 Sphere -322.2162 3.8537 Refraction 16.8468 L3 8 sphere 29.6639 9.0000 620410.6032 Refraction 14.0876 L4 9 sphere -28.7525 1.0000 711636.2959 Refraction 13.1654 10 Sphere 21.2205 2.3261 Refraction 10.8328 L5 11 Aspheric 28.0983 4.8956 'L-LAL13F' Refractive 10.6417 12 Aspheric 447.7671 2.5509 Refractive 9.9002 L6 13 Sphere -52.7374 1.0000 735228.2844 Refraction 9.3272 14 Sphere 32.6763 9.2757 Refraction 8.9481 L7 15 Sphere 60.2596 7.1276 519962.6714 Refraction 15.8500 16 Sphere -39.0610 0.1500 Refraction 16.2786 L8 17 Sphere -131.7368 1.0000 693899.3057 Refraction 16.9386 18 Sphere 49.3667 13.6163 Refraction 17.9406 L9 19 Sphere -984.6296 18.5194 590527.6197 Refraction 27.2300 20 Sphere -35.2783 0.1500 Refraction 28.5130 L10 21 Sphere 57.1056 8.2723 752255.3064 Refraction 30.6227 L11 22 Sphere 244.1650 6.6541 755201.2758 Refraction 30.3546 23 Sphere -132.2814 0.8497 Refraction 29.9636 L12 24 sphere -133.3243 1.0000 516699.5867 Refraction 28.7785 25 Sphere 486.4311 13.5653 Refraction 27.4481 L13 26 Sphere -48.8600 1.0000 664422.3250 Refraction 24.0641 27 Sphere 42.0940 9.8949 Refraction 24.4204 L14 28 Aspheric 63.6758 4.4911 'Z-330R' Refractive 26.1091 29 Aspheric 48.1826 1.3014 Refractive 27.1984 30 Sphere Infinity 3.0576 Refraction 28.1190 31 31 Aspheric -160.2731 9.2093 'Z-330R' Refractive 29.5260 32 Aspheric -45.8891 86.7907 Refractive 30.2123 41 33 Aspheric -54.2363 154.0000 'Z-330R' Refractive 41.8092 42 34 Aspheric 94.4167 -154.0000 'Z-330R' Reflection 101.6996 43 35 Aspheric 110.7354 154.0000 'Z-330R' Reflection 123.1516 44 36 Aspheric -31.7063 0.0000 Refractive 63.1950 37 Sphere Infinity 295.0820 Refraction 281.8608 S 38 Sphere Infinity 0.0000 Refraction 1423.7700

[0027] The aspheric coefficients are as follows:

[0028] Surface number S11 S12 S28 S29 R 28.0983 447.7671 63.6758 48.1826 K 0.0853 0 0.458034063 -10.5596866 A 1.03173E-06 8.65677E-06 -2.95275E-05 -2.24766E-05 B 5.91211E-09 3.23916E-08 4.67141E-08 3.60983E-08 C 4.00552E-10 -2.16413E-11 -7.44314E-11 -6.44200E-11 D -4.28051E-12 -1.69783E-12 1.41620E-13 1.06499E-13 E 1.53605E-14 2.52965E-14 -2.19886E-16 -1.39771E-16 F 1.89586E-16 1.11658E-17 2.18119E-19 1.12686E-19 G -1.63865E-18 -8.64798E-19 -9.05008E-23 -3.94115E-23 H 4.90367E-21 4.22411E-21

[0029] Surface number S31 S32 S33 S34 R -160.2731 -45.8891 -54.2363 94.4167 K 21.52137195 -0.967500303 -1.093881002 -42.5734219741 A -6.26964E-07 -1.78504E-06 -2.54783E-06 -1.22116E-07 B -4.17354E-10 -1.25470E-09 1.41619E-09 5.26590E-12 C 1.83771E-12 1.53496E-12 -1.77705E-13 -9.35969E-17

[0030] Surface number S35 S36 R 110.7354 -31.7063 K -7.0217115764 -0.7414668010 A 2.54912E-07 4.18339E-06 B -1.16574E-11 -6.72357E-10 C 4.92398E-16 -3.86472E-14 D -1.89694E-20 2.69393E-17

[0031] (Action and effect) According to this example, by attaching the attachment optical system 10A to the enlargement side of the projection optical system 3 of the projector 1, the first projection light B1 from the projection optical system 3 can be projected onto an image formation surface different from the enlargement side image formation surface of the projection optical system 3. In this example, the image formation surface of the projector system 100A is a plane perpendicular to the first optical axis N of the projection optical system 3. In addition, this image formation surface is located closer to the projection optical system 3 than the enlargement side image formation surface of the projection optical system 3. Specifically, the projection distance of the projection optical system 3 is 3776 mm, whereas the projection distance of the projector system 100A in which the attachment optical system 10A is attached to the enlargement side of the projection optical system 3 of the projector 1 is 295 mm. Therefore, by attaching the attachment optical system 10A to the projector 1, the focus of the projector 1 can be shortened.

[0032] Here, the attachment optical system 10A has an incident surface 41, which reflects light transmitted through the incident surface 41. The attachment optical system 10A has an optical element 21 including a first reflecting surface 42 that reflects light from the first reflecting surface 42, a second reflecting surface 43 that reflects light from the first reflecting surface 42, and an exit surface 44 that transmits light from the second reflecting surface 43. When the attachment optical system 10A is attached to the projection optical system 3, the second optical axis M of the optical element 21 is located on an extension of the first optical axis N of the projection optical system 3, and the first reflecting surface 42 and the exit surface 44 are continuous within an axial light flux passing region 40 of an axial light flux passing through the second optical axis M and the first optical axis N. Therefore, the second projection light B2 heading toward the screen S2 via the attachment optical system 10A can reach an extension of the first optical axis N of the projection optical system 3.

[0033] The attachment optical system 10A also includes an entrance surface 41 having a concave shape recessed in the Z2 direction, a first reflecting surface 42 having a convex shape protruding in the Z1 direction, a second reflecting surface 43 having a concave shape recessed in the Z1 direction, and an exit surface 44 having a convex shape protruding in the Z2 direction. With this configuration, the attachment optical system 10A can easily project the first projection light B1 from the projection optical system 3 at a wider angle and form an image with a short focus.

[0034] Furthermore, in this example, one optical element 21 has two reflecting surfaces, that is, a first reflecting surface 42 and a second reflecting surface 43, and two transmitting surfaces, that is, an entrance surface 41 and an exit surface 44. Therefore, the number of optical members in the attachment optical system 10A can be reduced.

[0035] In this example, an intermediate image 20 that is conjugate with the enlarged image projected on the imaging plane is formed inside the optical element 21. That is, the optical element 21 forms the intermediate image 20 inside, and re-images this intermediate image 20 on the imaging plane. Therefore, the attachment optical system 10A improves the imaging performance of the projected image. Also, if the intermediate image 20 is formed inside the optical element 21, the projection direction in which the projected image is projected can be easily changed by the optical element 21.

[0036] Furthermore, in this example, the attachment optical system 10A has a positive lens 31 arranged on the projection optical system 3 side of the optical element 21. Since the attachment optical system 10A is provided with such a positive lens 31, the imaging performance of the attachment optical system 10A can be improved.

[0037] Fig. 6 is a diagram showing the MTF on the enlarged side of the projector system. The horizontal axis of Fig. 6 is the spatial frequency, and the vertical axis is the contrast reproduction ratio. As shown in Fig. 6, the projector system 100A of this example has high resolution.

[0038] Here, in this example, the projector 1 is turned upside down, and then the attachment optical system 10A is attached to the projection optical system 3. As a result, as shown in FIG. 3, the light modulation element 2 of the projector 1 forms a projection image on the upper side with respect to the first optical axis N of the projection optical system 3. The first projection light B1 from the projection optical system 3 spreads from the first optical axis N to the lower side with respect to the first optical axis N. Meanwhile, the exit surface 44 of the attachment optical system 10A is located on the upper side with respect to the second optical axis M, and the first reflecting surface 42 and the second reflecting surface 43 are located on the lower side with respect to the second optical axis M. As a result, the second projection light B2 from the attachment optical system 10A spreads from the second optical axis M to the upper side with respect to the second optical axis M. In this way, the direction in which the projection light spreads can be aligned before and after the attachment optical system 10A is attached to the projector 1.

[0039] Note that, for example, if the projector 1 is provided with a shift mechanism that supports the light modulation element 2 movably along the Y direction on the reduction-side image formation surface of the projection optical system 3, the attachment optical system 10A can be attached to the projection optical system 3 without turning the projector 1 upside down. In this case, instead of turning the projector 1 upside down, the shift mechanism moves the light modulation element 2 along a direction perpendicular to the first optical axis N, so that the light modulation element 2 forms a projected image above the first optical axis N. As a result, the first projection light B1 emitted from the projection optical system 3 spreads from the first optical axis N to the left and right and below the first optical axis N. Therefore, when attaching the attachment optical system 10A to the projection optical system 3, the exit surface 44 is moved in the first direction. If the first reflecting surface 42 and the second reflecting surface 43 are positioned above the second optical axis M, and the first reflecting surface 42 and the second reflecting surface 43 are positioned below the second optical axis M, the second projection light B2 emitted from the attachment optical system 10A spreads upward from the second optical axis M.

[0040] Example 2 Fig. 7 is a ray diagram that illustrates a schematic view of the entire projector system 100B of Example 2. Fig. 8 is a ray diagram of the projection optical system 3 and the attachment optical system 10B of the projector 1. Fig. 9 is a configuration diagram of the attachment optical system 10B.

[0041] As shown in Fig. 7, the projector system 100B of this example of the embodiment 2 includes the projector 1 and an attachment optical system 10B that is detachably attached to the projection optical system 3 of the projector 1. When the attachment optical system 10B is attached to the projector 1, the second optical axis M of the attachment optical system 10B is located on an extension of the first optical axis N of the projection optical system 3. The imaging plane of the optical system of the projector system 100B, which is composed of the projection optical system 3 and the attachment optical system 10B, is a plane perpendicular to the first optical axis N of the projection optical system 3. The imaging plane of the optical system of the projector system 100B, i.e., the imaging plane of the attachment optical system 10B, is located closer to the projection optical system 3 than the magnification-side imaging plane of the projection optical system 3 of the projector 1. That is, the imaging surface of the attachment optical system 10B is a plane perpendicular to the first optical axis N and the second optical axis M, and the distance between the imaging surface and the projection optical system 3 is smaller than the distance between the enlargement-side imaging surface of the projection optical system 3 and the projection optical system 3. In this example, the imaging surface of the attachment optical system 10B is approximately parallel to the reduction-side imaging surface of the projection optical system 3 on which the light modulation element 2 included in the projector 1 forms the projected image. In this example, the projector 1 is the same as that in the first embodiment.

[0042] As shown in FIG. 8, the attachment optical system 10B includes a front group 11 and a rear group 12 (lens group). In this example, the front group 11 is made of one optical element 21. The rear group 12 includes, in order from the reduction side to the enlargement side, a positive lens 31, a positive lens 32 (second lens), and a negative lens 33 (third lens). The positive lens 32 and the negative lens 33 are disposed on the projection optical system 3 side with respect to the optical element 21. The positive lens 32 has positive power. The negative lens 33 is disposed on the enlargement side of the positive lens 32 and has negative power. The positive lens 32 and the negative lens 33 have different Abbe numbers. In this example, the positive lens 32 and the negative lens 33 are cemented together to form one cemented lens 34.

[0043] As shown in FIG. 9, the optical element 21 includes an incident surface 41 that transmits light from the cemented lens 34, a first reflecting surface 42 that reflects the light transmitted through the incident surface 41, a second reflecting surface 43 that reflects the light from the first reflecting surface 42, and an exit surface 44 that transmits the light from the second reflecting surface 43. That is, the optical element 21 includes the incident surface 41, the first reflecting surface 42 that reflects the light emitted from the incident surface 41, the second reflecting surface 43 that reflects the light reflected by the first reflecting surface 42, and the exit surface 44 that transmits the light reflected from the second reflecting surface 43. The incident surface 41, the first reflecting surface 42, the second reflecting surface 43, and the exit surface 44 all have shapes that are rotationally symmetric about the second optical axis M. The incident surface 41 is located on the second optical axis M. The incident surface 41 has a concave shape recessed in the Z2 direction. That is, the incident surface 41 has a concave shape recessed in a Z2 direction (second direction) opposite to the Z1 direction (first direction) in which the projection optical system 3 is located relative to the optical element 21 in the optical axis direction along the second optical axis M. The first reflecting surface 42 is located in the Z2 direction of the incident surface 41. The first reflecting surface 42 is also disposed in the Y1 direction with respect to the second optical axis M. The first reflecting surface 42 has a convex shape protruding in the Z1 direction. The second reflecting surface 43 is located in the Z1 direction of the first reflecting surface 42. The second reflecting surface 43 is also disposed in the Y1 direction with respect to the second optical axis M, similar to the first reflecting surface 42. The second reflecting surface 43 has a concave shape recessed in the Z1 direction. The exit surface 44 is located in the Z2 direction of the second reflecting surface 43. The exit surface 44 is also disposed in the Y2 direction with respect to the second optical axis M. The exit surface 44 has a convex shape protruding in the Z2 direction.

[0044] As shown in FIG. 9, the first reflecting surface 42 and the exit surface 44 are continuous in the Y direction within an axial light flux passing region (axial region) 40 of the axial light flux passing through the second optical axis M. That is, the axial light flux passing region 40 is a part of the first reflecting surface 42 and a part of the exit surface 44. The axial light flux is light passing through the first optical axis N and the second optical axis M when the attachment optical system 10B is attached to the projector 1. That is, the axial light flux passing region 40 is a region of the optical element 21 where light passes through the first optical axis N and the second optical axis M. Here, the second optical axis M is the design axis of the optical element 21. The axial light flux passing region 40 is a region that is uniquely defined when designing the optical element 21.

[0045] The first reflecting surface 42 is formed by providing a reflective coating layer on the outer surface of the optical element 21 in the Z2 direction. In the first reflecting surface 42, a half-mirror coating layer is provided as a reflective coating layer on a portion overlapping with the axial light beam passing region 40. This allows light traveling along the second optical axis M in the Z2 direction to reach the screen S2. In addition, the first reflecting surface 42, the second reflecting surface 43, and the exit surface 44 have portions closer to the second optical axis M that overlap with the incident surface 41 when viewed from the Z direction. In the second reflecting surface 43, the first reflecting portion 431 that does not overlap with the incident surface 41 when viewed from the Z direction is formed by providing a reflective coating layer on the outer surface of the optical element 21 in the Z1 direction. In the second reflecting surface 43, the second reflecting portion 432 that overlaps with the incident surface 41 when viewed from the Z direction is formed by providing a half-mirror coating layer as a reflective coating layer that transmits light traveling in the Z2 direction and reflects light traveling in the Z1 direction.

[0046] Here, an intermediate image 20 that is conjugate with the enlarged image projected on the imaging plane is formed inside the optical element 21. The intermediate image 20 is also conjugate with the projected image formed on the reduction-side imaging plane of the projection optical system 3. In this example, the intermediate image 20 is formed between the first reflecting surface 42 and the second reflecting surface 43.

[0047] (Lens data) The projection distance of the projection optical system 3 is 3776 mm. The projection distance of the projector system 100B consisting of the projection optical system 3 and the attachment optical system 10B is 295 mm. The numerical aperture of the optical system of the projector system 100B consisting of the projection optical system 3 and the attachment optical system 10B is 0.291. The lens data of this optical system is as follows. The surface numbers are assigned in order from the reduction side to the enlargement side. The symbols are the symbols of the liquid crystal panel, prism, lens, positive lens, positive lens, negative lens, first transmitting surface, first reflecting surface, second reflecting surface, second transmitting surface, and screen. The data of the surface numbers that do not correspond to the liquid crystal panel, prism, lens, positive lens, positive lens, negative lens, first transmitting surface, first reflecting surface, second reflecting surface, second transmitting surface, and screen are dummy data. R is the radius of curvature. D is the axial surface distance. C is the aperture radius. The units of R, D, and C are mm. The integer part of the numerical value shown for the glass material represents the refractive index multiplied by 10 to the power of 6, and the decimal part represents the Abbe number multiplied by 10 to the power of 2.

[0048] Symbol Surface number Shape RD Glass material Refraction / Reflection C 0 Sphere Infinity 0.0000 Refraction 0.0000 2 1 Sphere Infinity 1.0000 Refraction 11.8500 5 2 Sphere Infinity 31.5200 BSC7_HOYA Refraction 12.0421 3 Sphere Infinity 10.5830 Refraction 15.9895 L1 4 sphere 63.4927 6.2427 755201.2758 Refraction 18.5302 5 sphere -86.6504 0.1500 Refraction 18.4984 L2 6 sphere 113.0626 8.0000 620410.6032 Refraction 17.7500 7 Sphere -322.2162 3.8537 Refraction 16.8468 L3 8 sphere 29.6639 9.0000 620410.6032 Refraction 14.0876 L4 9 sphere -28.7525 1.0000 711636.2959 Refraction 13.1654 10 Sphere 21.2205 2.3261 Refraction 10.8328 L5 11 Aspheric 28.0983 4.8956 'L-LAL13F' Refractive 10.6417 12 Aspheric 447.7671 2.5509 Refractive 9.9002 L6 13 Sphere -52.7374 1.0000 735228.2844 Refraction 9.3272 14 Sphere 32.6763 9.2757 Refraction 8.9481 L7 15 Sphere 60.2596 7.1276 519962.6714 Refraction 15.8500 16 Sphere -39.0610 0.1500 Refraction 16.2786 L8 17 Sphere -131.7368 1.0000 693899.3057 Refraction 16.9386 18 Sphere 49.3667 13.6163 Refraction 17.9406 L9 19 Sphere -984.6296 18.5194 590527.6197 Refraction 27.2300 20 Sphere -35.2783 0.1500 Refraction 28.5130 L10 21 Sphere 57.1056 8.2723 752255.3064 Refraction 30.6227 L11 22 Sphere 244.1650 6.6541 755201.2758 Refraction 30.3546 23 Sphere -132.2814 0.8497 Refraction 29.9636 L12 24 sphere -133.3243 1.0000 516699.5867 Refraction 28.7785 25 Sphere 486.4311 14.0443 Refraction 27.4481 L13 26 Sphere -48.8600 1.0000 664422.3250 Refraction 24.0641 27 Sphere 42.0940 9.8949 Refraction 24.4204 L14 28 Aspheric 63.6758 4.4911 'Z-330R' Refractive 26.1091 29 Aspheric 48.1826 0.8324 Refractive 27.1984 30 Sphere Infinity 6.5446 Refraction 27.9236 31 31 Sphere -65.0778 6.0652 BK7_SCHOTT Refraction 28.0042 32 Sphere -45.1776 34.8592 Refraction 30.2455 32 33 Sphere 74.0561 40.9792 563944.6367 Refraction 44.5791 33 34 Sphere -50.2699 13.4768 592429.5950 Refraction 44.1768 35 Sphere 150.8414 28.1248 Refraction 40.1403 41 36 Aspheric -35.5750 154.0000 'Z-330R' Refractive 40.1407 42 37 Aspheric 136.8952 -154.0000 'Z-330R' Reflection 108.6154 43 38 Aspheric 117.4779 154.0000 'Z-330R' Reflection 122.2696 44 39 Aspheric -34.0536 0.0000 Refractive 65.2586 40 Sphere Infinity 295.0820 Refraction 302.8489 S 41 Sphere Infinity 0.0000 Refraction 1421.9277

[0049] The aspheric coefficients are as follows:

[0050] Surface number S11 S12 S28 S29 R 28.0983 447.7671 63.6758 48.1826 K 0.0853 0 0.458034063 -10.5596866 A 1.03173E-06 8.65677E-06 -2.95275E-05 -2.24766E-05 B 5.91211E-09 3.23916E-08 4.67141E-08 3.60983E-08 C 4.00552E-10 -2.16413E-11 -7.44314E-11 -6.44200E-11 D -4.28051E-12 -1.69783E-12 1.41620E-13 1.06499E-13 E 1.53605E-14 2.52965E-14 -2.19886E-16 -1.39771E-16 F 1.89586E-16 1.11658E-17 2.18119E-19 1.12686E-19 G -1.63865E-18 -8.64798E-19 -9.05008E-23 -3.94115E-23 H 4.90367E-21 4.22411E-21

[0051] Face number S36 S37 S38 S39 R -35.5750 136.8952 117.4779 -34.0536 K -1.194781095 -69.64270173 -1.013592364 -0.7150019510 A -3.70737E-06 -1.18711E-07 -6.12974E-08 2.80685E-06 B 1.30118E-09 5.93873E-12 1.29269E-11 -3.19369E-10 C 8.60165E-14 -1.53636E-16 -8.09145E-16 -4.61825E-14 D 1.15686E-20 1.64220E-17

[0052] The Abbe numbers νd of the positive lens 32 and the negative lens 33 are as follows:

[0053] Code Surface number vd 32 33 63.67 33 34 59.50

[0054] (Action and effect) According to the projector system 100B of this example, it is possible to obtain the same effects as those of the above-mentioned projector system 100A. In this example, the projection distance of the projection optical system 3 is 3776 mm, whereas the projection distance of the projector system 100B in which the attachment optical system 10B is attached to the enlarged side of the projection optical system 3 of the projector 1 is 295 mm.

[0055] Furthermore, in this example, the attachment optical system 10B has a rear group 12 having positive power and arranged in the Z1 direction of the optical element 21. Therefore, the imaging performance of the attachment optical system 10B can be improved.

[0056] Furthermore, the positive lens 32 and the negative lens 33 that form the rear group 12 have different Abbe numbers. Therefore, according to the projector system 100B of this example, chromatic aberration can be easily corrected.

[0057] Fig. 10 is a diagram showing the MTF on the enlarged side of the projector system 100B. The horizontal axis of Fig. 10 is the spatial frequency, and the vertical axis is the contrast reproduction ratio. As shown in Fig. 10, the projector system 100B of this example has high resolution. [Explanation of symbols]

[0058] REFERENCE SIGNS LIST 1...projector, 2...light modulation element, 3...projection optical system, 4...casing, 5...prism, 10A, 10B...attachment optical system, 11...front group, 12...rear group, 20...intermediate image, 21...optical element, 22...first member, 23...second member, 26...first outer surface portion, 27...second outer surface portion, 31...positive lens, 32...positive lens, 33...negative lens, 34...cemented lens , 40...axial light beam passing area, 41...incident surface, 42...first reflecting surface, 43...second reflecting surface, 44...exiting surface, 100A, 100B...projector system, 431...first reflecting section, 432...second reflecting section, B1...first projection light, B2...second projection light, F0 to F10...light beam, L1 to L14...lenses, N...first optical axis, M...second optical axis, S1, S2...screens.

Claims

1. An attachment optical system is detachably attached to an enlargement side of a projection optical system included in a projection display device, and projects projection light emitted from the projection optical system onto an image forming surface different from an enlargement side image forming surface of the projection optical system, an optical element having a second optical axis disposed on an extension of the first optical axis of the projection optical system; the optical element includes an incident surface disposed on the second optical axis, a first reflecting surface that reflects light emitted from the incident surface, a second reflecting surface that reflects the light reflected by the first reflecting surface, and an exit surface that transmits the light reflected by the second reflecting surface, the first reflecting surface and the exit surface are continuous within an on-axis region where light passes through the second optical axis and the first optical axis; The attachment optical system, wherein the image forming surface of the attachment optical system is approximately parallel to a reduction-side image forming surface of the projection optical system on which a light modulation element provided in the projection display device forms a projected image.

2. the entrance surface has a concave shape recessed in a second direction opposite to a first direction in which the projection optical system is located relative to the optical element in an optical axis direction along the second optical axis, the first reflecting surface has a convex shape protruding in the first direction, the second reflecting surface has a concave shape recessed in the first direction, The attachment optical system according to claim 1 , wherein the exit surface has a convex shape that protrudes in the second direction.

3. 3. The attachment optical system according to claim 1, wherein an intermediate image conjugate with the enlarged image projected onto the image forming surface is formed inside the optical element.

4. 4. The attachment optical system according to claim 1, further comprising a first lens having a positive power, the first lens being arranged on the projection optical system side with respect to the optical element.

5. a lens group having a positive power, the lens group being disposed on a side of the projection optical system with respect to the optical element; the lens group includes a second lens having a positive power and a third lens having a negative power; 4. The attachment optical system according to claim 1, wherein the second lens and the third lens have different Abbe numbers.

6. the imaging surface is a plane perpendicular to the first optical axis and the second optical axis, 6. The attachment optical system according to claim 1, wherein a distance between the image forming surface and the projection optical system is smaller than a distance between the enlargement-side image forming surface and the projection optical system.

7. An attachment optical system according to any one of claims 1 to 6; A projection display device including a projection optical system, A projection display system, characterized in that the attachment optical system is detachably attached to the projection optical system.

8. The projection display device includes a light modulation element that modulates light emitted from a light source to form a projection image; the light modulation element is disposed on a reduction-side image forming surface of the projection optical system, and forms the projected image on one side with respect to the first optical axis of the projection optical system; the first projection light emitted from the projection optical system spreads to the other side with respect to the first optical axis, the first reflecting surface and the second reflecting surface are disposed on the other side with respect to the second optical axis, the exit surface is disposed on one side with respect to the second optical axis, 8. The projection display system according to claim 7, wherein the second projection light emitted from the attachment optical system spreads to one side with respect to the second optical axis.

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