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 included in a projection display device and projects projection light emitted from the projection optical system 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.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 the same 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. As a result, the enlarged image of the projection image projected via the projection optical system and the attachment optical system is formed on an image forming surface having an arc shape extending in the circumferential direction around the optical axis of the projection optical system. [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 surface other than the enlarged side image surface of the projection optical system, the attachment optical system having 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 having an entrance surface arranged on the second optical axis, a first reflecting surface that reflects light emitted from the entrance 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 being continuous within an on-axis region where light passes through the second optical axis and the first optical axis.

[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 an example of an entire projector system according to a 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, has the shape of the inner surface of a spherical portion obtained by dividing a sphere. In this example, the image forming surface of the attachment optical system 10A has the shape of the inner surface of a spherical portion obtained by dividing a sphere into four equal parts. The shape of the image forming surface of the projector system 100A is different from the shape of the magnification 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 can project a projection image onto an image forming surface different from that of the projection optical system 3. When the projector system 100A is used, a screen S2 having the shape of the inner surface of a spherical portion obtained by dividing a sphere into four equal parts is disposed on the image forming surfaces 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 direction and upward 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 L11 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 L11 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 reflectively coated. The optical element 21 includes an entrance surface 41 that transmits light from the positive lens 31, a first reflecting surface 42 that reflects light transmitted through the entrance surface 41, 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. That is, the optical element 21 includes the entrance surface 41, the first reflecting surface 42 that reflects light emitted from the entrance surface 41, the second reflecting surface 43 that reflects light reflected by the first reflecting surface 42, and an exit surface 44 that transmits light 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 and heading in the Z1 direction Part ofThe 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, 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 second reflecting surface 43 and the exit surface 44.

[0025] (Lens data) 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 interval. 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 value obtained by multiplying the refractive index by 10 to the power of 6, and the decimal part represents the value obtained by multiplying the Abbe number by 10 to the power of 2.

[0026] Symbol Surface number Shape RD Glass material Refraction / Reflection C 2 0 Sphere Infinity 0.0010 Refraction 0.0000 5 1 Sphere Infinity 29.9441 BSC7_HOYA Refraction 11.0003 2 Sphere Infinity 10.7129 Refraction 16.1307 3 Sphere Infinity 1.3170 Refraction 18.9729 L1 4 sphere 100.7098 5.4431 713667.2948 Refraction 19.8463 5 sphere -102.1154 0.1500 Refraction 19.9390 L2 6 Sphere 43.1770 6.7243 643138.5620 Refraction 19.6870 7 Sphere -398.2098 14.3689 Refraction 19.3609 L3 8 sphere 25.7153 7.0237 487490.7041 Refraction 12.0000 L4 9 sphere -26.9720 1.0000 755201.2758 Refraction 11.4463 10 Sphere 22.7296 7.0498 Refraction 10.1942 L5 11 Aspheric -12.8094 2.0000 'D-ZF10_K' Refraction 10.2226 12 Aspheric -23.2033 0.2735 Refractive 11.0391 L6 13 Sphere 33.2589 2.0000 750866.3234 Refraction 12.2908 L7 14 Sphere 21.4173 8.9545 487490.7041 Refraction 12.5458 15 Sphere -32.3154 17.4196 Refraction 13.0465 L8 16 Sphere 457.8045 8.8399 749259.3458 Refraction 16.0000 17 Sphere -40.7661 3.8120 Refraction 16.7967 L9 18 Sphere 38.3424 9.0000 743972.4485 Refraction 16.2071 19 Sphere 52.1088 9.2806 Refraction 14.5342 L10 20 Sphere -24.1062 1.0000 504633.6129 Refraction 14.0641 21 Sphere 34.0901 3.0358 Refraction 15.2438 L11 22 Aspheric 35.8481 4.3495 'Z-E48R' Refractive 16.1241 23 Aspheric 34.7555 0.2748 Refractive 17.0742 24 sphere infinity 2.7542 refraction 15.8710 31 25 Aspheric 167.7799 3.4688 'Z-330R' Refractive 17.0088 26 Aspheric -141.4036 26.5312 Refractive 17.2791 41 27 Aspheric -247.3414 174.6000 'Z-330R' Refractive 25.0955 42 28 Aspheric 361.1475 -174.6000 'Z-330R' Reflection 64.3156 43 29 Aspheric 165.2666 174.6000 'Z-330R' Reflection 137.5994 44 30 Aspheric -309.4117 10.0000 Refractive 83.0000 31 Sphere Infinity 2768.0000 Refraction 1781.1106 S 32 Sphere -2,768.0000 0.0000 Refraction 2906.3556

[0027] The aspheric coefficients are as follows:

[0028] Surface number S11 S12 S22 S23 R -12.8094 -23.2033 35.8481 34.7555 K 0 0 -0.007858933 -8.273411949 A 1.97478E-04 1.50407E-04 -4.73415E-05 -3.44381E-05 B -8.21635E-07 -7.62802E-07 1.11583E-07 7.17727E-08 C 8.67659E-09 5.19871E-09 -1.60660E-10 -1.26152E-10 D -2.93527E-11 -2.35712E-11 1.88569E-13 1.10885E-13 E -3.30348E-14 4.53875E-14 -1.74526E-16 -3.42914E-17 F 7.83942E-16 2.61603E-19 -1.13308E-20

[0029] Face number S25 S26 S27 S28 R 167.7799 -141.4036 -247.3414 361.1475 K 0 0 -75.66565551 -88.2104460231 A -3.71721E-06 -5.46556E-06 -2.74520E-06 1.55519E-08 B 5.05896E-10 2.74825E-10 6.45342E-10 3.41360E-11 C 6.79321E-12 5.93487E-12 1.67714E-13 -4.59596E-15 D -2.13955E-15 1.80004E-15

[0030] Face number S29 S30 R 165.2666 -309.4117 K -3.9406340359 -23.8997256640 A 6.69798E-08 -5.56825E-07 B -2.30309E-12 7.93919E-11 C 2.30442E-16 -8.83324E-15 D -5.62829E-21 4.15649E-19

[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 has the shape of the inner surface of a spherical portion obtained by dividing a sphere into four equal parts. Therefore, by viewing the enlarged image inside this image formation surface, the viewer can get the sensation of being enveloped in the image.

[0032] Here, the attachment optical system 10A has an optical element 21 having an incident surface 41, a first reflecting surface 42 that reflects light transmitted through the incident surface 41, 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 the axial light flux passing through the second optical axis M and the first optical axis N. Therefore, the second projection light B2 directed 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, a first reflecting surface 42 and The attachment optical system 10A includes 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, when the projector 1 includes 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, if the exit surface 44 is 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 will spread 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 second embodiment is composed of 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 image plane of the optical system of the projector system 100B 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 surface of the optical system of projector system 100B, i.e., the imaging surface of attachment optical system 10B, has the shape of the inner surface of a spherical portion obtained by dividing a sphere. In this example, the imaging surface of attachment optical system 10B also has the shape of the inner surface of a spherical portion obtained by dividing a sphere into four equal parts. In this example, projector 1 is the same as in Example 1.

[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 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 overlap with the incident surface 41 at the portions closer to the second optical axis M 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 has a half-mirror coating layer as a reflective coating layer in the Z2 direction. It is formed by providing a half mirror coating layer that transmits light heading in the Z1 direction and reflects light heading in the Z2 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 second reflecting surface 43 and the exit surface 44.

[0047] (Lens data) 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, 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, 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 interval. 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 value obtained by multiplying the refractive index by 10 to the power of 6, and the decimal part represents the value obtained by multiplying the Abbe number by 10 to the power of 2.

[0048] Symbol Surface number Shape RD Glass material Refraction / Reflection C 2 0 Sphere Infinity 0.0010 Refraction 0.0000 5 1 Sphere Infinity 29.9441 BSC7_HOYA Refraction 11.0003 2 Sphere Infinity 10.7129 Refraction 16.1307 3 Sphere Infinity 1.3170 Refraction 18.9729 L1 4 sphere 100.7098 5.4431 713667.2948 Refraction 19.8463 5 sphere -102.1154 0.1500 Refraction 19.9390 L2 6 Sphere 43.1770 6.7243 643138.5620 Refraction 19.6870 7 Sphere -398.2098 14.3689 Refraction 19.3609 L3 8 sphere 25.7153 7.0237 487490.7041 Refraction 12.0000 L4 9 sphere -26.9720 1.0000 755201.2758 Refraction 11.4463 10 Sphere 22.7296 7.0498 Refraction 10.1942 L5 11 Aspheric -12.8094 2.0000 'D-ZF10_K' Refraction 10.2226 12 Aspheric -23.2033 0.2735 Refractive 11.0391 L6 13 Sphere 33.2589 2.0000 750866.3234 Refraction 12.3328 L7 14 Sphere 21.4173 8.9545 487490.7041 Refraction 12.5458 15 Sphere -32.3154 17.4196 Refraction 13.0465 L8 16 Sphere 457.8045 8.8399 749259.3458 Refraction 16.0000 17 Sphere -40.7661 4.0868 Refraction 16.7967 L9 18 Sphere 38.3424 9.0000 743972.4485 Refraction 16.2071 19 Sphere 52.1088 9.1700 Refraction 14.5342 L10 20 Sphere -24.1062 1.0000 504633.6129 Refraction 14.0641 21 Sphere 34.0901 3.0358 Refraction 15.2438 L11 22 Aspheric 35.8481 4.3495 'Z-E48R' Refractive 16.1241 23 Aspheric 34.7555 0.1106 Refractive 17.0742 24 Sphere Infinity 2.8323 Refraction 15.8215 32 25 Sphere 43.7364 16.0000 743972.4485 Refraction 18.4063 33 26 Sphere -31.0380 14.0000 655261.3319 Refraction 18.3243 27 Sphere 48.6756 11.2070 Refraction 18.6311 41 28 Aspheric -54.4874 100.0000 'Z-330R' Refractive 18.5177 42 29 Aspheric 223.2230 -100.0000 'Z-330R' Reflection 63.3811 43 30 Aspheric 103.6949 100.0000 'Z-330R' Reflection 105.9951 44 31 Aspheric -27.7762 10.0000 Refractive 26.5136 32 Sphere Infinity 2768.0000 Refraction 1781.1106 S 33 Sphere -2,768.0000 0.0000 Refraction 2906.3556

[0049] The aspheric coefficients are as follows:

[0050] Surface number S11 S12 S22 S23 R -12.8094 -23.2033 35.8481 34.7555 K 0 0 -0.007858933 -8.273411949 A 1.97478E-04 1.50407E-04 -4.73415E-05 -3.44381E-05 B -8.21635E-07 -7.62802E-07 1.11583E-07 7.17727E-08 C 8.67659E-09 5.19871E-09 -1.60660E-10 -1.26152E-10 D -2.93527E-11 -2.35712E-11 1.88569E-13 1.10885E-13 E -3.30348E-14 4.53875E-14 -1.74526E-16 -3.42914E-17 F 7.83942E-16 2.61603E-19 -1.13308E-20

[0051] Face number S28 S29 S30 S31 R -54.4874 223.2230 103.6949 -27.7762 K 6.310243724 -53.5848539 -0.067701944 0.2099999992 A -5.18277E-06 3.89713E-07 1.60601E-07 -3.91584E-06 B -6.74401E-09 -1.00892E-10 -4.18496E-11 3.56467E-08 C -8.72598E-12 1.14220E-14 4.57110E-15 -1.20957E-10 D -2.11538E-19 1.98212E-13 E -1.24378E-16

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

[0053] Code Surface number vd 32 25 44.85 33 26 33.19

[0054] (Action and effect) According to projector system 100B of this example, it is possible to obtain the same effects as those of projector system 100A described above.

[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 L11...lens, N...first optical axis, M...second optical axis, S1, S2...screen.

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, An attachment optical system, characterized in that 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.

2. 2. The attachment optical system according to claim 1, wherein the image forming surface of the attachment optical system has a shape of an inner surface of a divided spherical portion of a sphere.

3. 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.

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

5. 5. 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.

6. 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; 5. The attachment optical system according to claim 1, wherein the second lens and the third lens have different Abbe numbers.

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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